ELECTRODE FOR CHARGING PARTICLE FILTER

BACKGROUND

[0001] Some imaging apparatuses are provided with a device that collects fine particles in a housing of the imaging apparatus. Such a device includes a negative-ion-generation unit that generates negative ions in order to charge the particles, and an electret filter that is positively charged in order to trap the charged particles.

BRIEF DESCRIPTION OF DRAWINGS

[0002] FIG. 1 is a schematic view of an example imaging apparatus.

[0003] FIG. 2 is a block diagram of an example collection device.

[0004] FIG. 3 is a schematic diagram of a charging device in the example collection device illustrated in FIG. 2.

[0005] FIG. 4 is a schematic diagram of the charging device illustrated in FIG. 2.

[0006] FIG. 5 is a schematic diagram illustrating a portion of the charging device, illustrating a filter-charging anode electrode according to an example. [0007] FIG. 6 is a graph illustrating an example relationship between cumulative number of printed sheets and a surface potential of a filter.

[0008] FIG. 7 is a graph illustrating an example relationship between a use temperature of a fixing device and a charging cycle of the filter.

[0009] FIG. 8 is a block diagram of another example collection device.

[0010] FIG. 9 is a schematic diagram of a charging device in the example collection device illustrated in FIG. 8.

[0011] FIG. 10 is a schematic diagram of the charging device illustrated in FIG. 8.

[0012] FIG. 11 is a block diagram of another example collection device.

[0013] FIG. 12 is a schematic diagram of a charging device in the example collection device illustrated in FIG. 11. [0014] FIG. 13 is a block diagram of another example collection device.

[0015] FIG. 14 is a schematic diagram of an example charging device in the example collection device illustrated in FIG. 13.

[0016] FIG. 15 is a schematic diagram of another example charging device.

[0017] FIG. 16 is a schematic diagram of another example charging device.

[0018] FIG. 17 is a schematic diagram of another example charging device.

[0019] FIG. 18 is a block diagram of another example collection device.

[0020] FIG. 19 is a schematic view of a charging device in the example collection device illustrated in FIG. 18.

DETAILED DESCRIPTION

[0021] In a filter collecting electrically-charged particles via static electricity, the static electricity may weaken over time (e.g., becomes weak in accordance with a lapse of time) or the like, such that a collection rate of the electrically- charged particles decreases. When the collection rate of the electrically-charged particles of the filter decreases, it is necessary to replace the filter. A life cycle (or replacement cycle) of the filter may be extended by charging the filter collecting electrically-charged fine particles via static electricity, so as to reduce a maintenance cost for an imaging apparatus.

[0022] In some examples, an imaging apparatus may include a filter that collects electrically-charged particles via static electricity, and a charging device that charges the filter. The example charging device may include an electrode emitting filter-charging ions in order to charge the filter.

[0023] Another example imaging apparatus may include a filter that collects electrically-charged particles via static electricity, and a charging device that charges the filter and that charges the particles in order to form the electrically-charged particles to be collected. The example charging device may be configured to emit first ions toward the filter in order to charge the filter and to emit second ions to the particles in order to form the electrically-charged particles to be collected, and the second ions may have a polarity different from that of the first ions. [0024] Hereinafter, an example imaging apparatus will be described with reference to the drawings. The imaging apparatus may refer to a device such as a printer or the like, or to a device to be used in the imaging apparatus. In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted.

[0025] With reference to FIG. 1 , an example imaging apparatus 1 may form a color image by using toners in the four colors of magenta, yellow, cyan, and black (MYCK). The imaging apparatus 1 includes a conveyance device 10 that conveys a recording medium such as paper 3, image carriers 20M, 20Y, 20C, and 20K on which electrostatic latent images are formed, developing devices 30M, 30Y, 30C, and 30K forming single-color toner images by developing the electrostatic latent images with the magenta, yellow, cyan, and black toners, respectively, toner tanks 21 M, 21 Y, 21 C and 21 K to supply the magenta, yellow, cyan, and black toners, respectively, a transfer device 40 on which the single color toner images are layered into a composite toner image and that transfers the composite toner image to the paper (or sheet of paper) 3, a fixation device (or fixing device) 50 that fixes the toner image to the paper 3, a discharge device 60 that discharges the paper 3, and a controller 70 that controls the operation of the imaging apparatus 1 .

[0026] The conveyance device 10 conveys the paper 3 as the recording medium along a conveyance route 11. Prior to reaching the conveyance route 11 , the paper 3 is stacked in a cassette 12, and is picked up and conveyed by a paper feeding roller 13.

[0027] The image carriers 20M, 20Y, 20C, and 20K which may also be referred to as electrostatic latent image carriers, photoreceptor drums, or the like, form respective electrostatic latent images for generating a magenta toner image, a yellow toner image, a cyan toner image, and a black toner image, respectively. Each of the image carriers 20M, 20Y, 20C, and 20K have a similar configuration. Accordingly, the image carrier 20M will be described as a representative image carrier for ease of understanding, and one or more of the image carriers 20M, 20Y, 20C, and 20K may be described separately when suitable. [0028] The image carrier 20M is surrounded by the developing device 30M, a charging roller 22M, an exposure unit (or exposure device) 23, and a cleaning unit (or cleaning device) 24M. Similarly, each of image carriers 20Y, 20C, and 20K is surrounded by a corresponding one of the developing devices 30Y, 30C, and 30K, by a charging roller similar to the charging roller 22M, and by a cleaning unit similar to the cleaning unit 24M. Additionally, the exposure unit 23 is also positioned adjacent the image carriers 20Y, 20C, and 20K.

[0029] The charging roller 22M charges the surface (e.g., circumferential surface) of the image carrier 20M to a predetermined potential. The charging roller 22M rotates in accordance with the rotation of the image carrier 20M. The exposure unit 23 exposes the surface of the image carrier 20M that is charged by the charging roller 22M, in accordance with the image to be formed on the paper 3. Accordingly, the potential of a portion of the surface of the image carrier 20M that is exposed by the exposure unit 23, is changed, to form an electrostatic latent image. The cleaning unit 24M recovers a remaining toner on the image carrier 20M.

[0030] The developing device 30M develops the electrostatic latent image formed on the image carrier 20M with the toner supplied from the toner tank 21 M which contains a magenta toner and a carrier, in order to form the magenta toner image on the image carrier 20 M. The developing devices 30M, 30Y, 30C, and 30K have similar configurations to carry out similar operations, so as to form the yellow toner image, the cyan toner image and the black toner image on the respective image carriers 20Y, 20C and 20K. Accordingly, the developing device 30M will be described as a representative developing device for ease of understanding, and one or more of the developing devices 30M, 30Y, 30C, and 30K may be described separately when suitable.

[0031] The developing device 30M includes a developing roller 31 M to carry the toner to the image carrier 20M. The developing device 30M uses a two- component developer containing the toner (e.g., the magenta toner) and a carrier, as the developer. That is, in the developing device 30M, the toner and the carrier are adjusted to a targeted mixing ratio, and are further mixed and stirred to disperse the toner, to obtain a developer having an optimal or targeted charging amount. The developer is carried on the developing roller 31 M and conveyed to a region facing the image carrier 20M, with the rotation of the developing roller 31 M, where the toner in the developer transfers to the electrostatic latent image formed on the circumferential surface of the image carrier 20M, so as to develop the electrostatic latent image.

[0032] The transfer device 40 forms a conveying surface to layer the single-color toner image formed by each of the developing devices 30M, 30Y, 30C, and 30K, into a single composite toner image, and to convey and transfer the composite toner image to the paper 3. Namely, the transfer device 40 includes a transfer belt 41 to which the single-color toner images are primarily transferred from the respective image carriers 20M, 20Y, 20C, and 20K, suspension rollers 44, 45, 46, and 47 that support the transfer belt 41 , primary transfer rollers 42M, 42Y, 42C, and 42K located adjacent the image carriers 20M, 20Y, 20C, and 20K, respectively, opposite the transfer belt 41 , in order to primarily transfer the single color toner images from the respective image carriers 20M, 20Y, 20C, and 20K to the transfer belt 41 , and a secondary transfer roller 43 located adjacent the suspension roller 47, opposite the transfer belt 41 , to secondarily transfer the composite toner image to the paper 3 from the transfer belt 41.

[0033] The transfer belt 41 is an endless belt that is is rotated by the suspension rollers 44, 45, 46, and 47, in which the suspension roller 47 is a driving roller, and the suspension rollers 44, 45, and 46 are a driven rollers. The primary transfer rollers 42M, 42Y, 42C and 42K are pressed against the respective image carriers 20M, 20Y, 20C and 20K from the inner circumference side of the transfer belt 41. The secondary transfer roller 43 which is disposed parallel to the suspension roller 47 with the transfer belt 41 interposed therebetween, is pressed against the suspension roller 47 from the outer circumference side of the transfer belt 41 , to form a transfer nip region 14 between the secondary transfer roller 43 and the transfer belt 41 , for transferring the composite toner image from the transfer belt 41 to the paper 3.

[0034] The fixing device 50 conveys the paper 3 to pass through a fixing nip region for heating and pressing, in order to attach the toner image to the paper 3. The fixing device 50 includes a heating roller 52 to heat the paper 3 (with a heat source such as a halogen lamp inside, for example), and further includes a pressure roller 54 that is rotatably driven while applying pressure toward the heating roller 52. A contact region between the heating roller 52 and the pressure roller 54 forms a fixing nip region where the paper 3 passes to fuse and fix the toner image to the paper 3.

[0035] The discharge device 60 includes discharge rollers 62 and 64 for discharging the paper 3 on which the toner image is fixed by the fixing device 50 to the outside the device.

[0036] The controller 70 is an electronic control unit including a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and the like. A program stored in the ROM, for example in the form of processor-readable data and instruction, may be loaded in the RAM, and executed by the CPU, to carry out various controls and operations in the above- described components of the imaging apparatus 1. The controller 70 may include a plurality of electronic control components, or may include a single electronic control device. The controller 70 performs various controls in the imaging apparatus 1 .

[0037] The example imaging apparatus 1 includes a housing 2 that houses the above-described components. An operation of the fixing device 50 may cause particles to be released in a space 4 within the housing 2. With reference to FIGS. 1 and 2, the example imaging apparatus 1 includes a collection device 80 to collect particles floating in a housing space 4 that is defined in a housing 2 of the imaging apparatus 1 . The particles to be collected by the collection device 80 may be ultrafine particles (UFP), for example, having a size of approximately 5 nm to 300 nm. The particles, for example, are generated from the toner and the paper to be heated by the fixing device 50, the component of the fixing device 50, or other peripheral components. The collection device 80 is disposed in a position adjacent to the fixing device 50 in which a generation amount of the particles is relatively large, in order to more effectively collect the particles.

[0038] With reference to FIG. 2, the collection example device 80 may include a filter 81 , an air flow generation device 82, and a charging device 83. [0039] The filter 81 collects the electrically-charged particles via static electricity. In the filter 81 , the surface of the filter 81 is charged, and thus, the electrically-charged particles can be collected by a coulomb force. The surface of the filter 81 may be charged positively or negatively. In addition, at least a part of the surface of the filter 81 may be charged to have polarity that is counter (opposite) to a polarity of the electrically-charged particles. As an example, the electrically-charged particles may be charged positively, and the surface of the filter 81 may be charged negatively.

[0040] The filter 81 may be formed of a plurality of polymer sheets that are layered, and subjected to an electret treatment. The electret treatment, for example, is a treatment in which a polymer material that is heated and fused has a structure for retaining electrical-charging by solidifying the polymer material while applying a high voltage. The filter 81 , for example, may have a simple layer structure, a honeycomb structure, or a corrugated structure. The filter 81 may be charged at the time of collecting the electrically-charged particles. Accordingly, the filter 81 may be set in advance to be charged, or may be charged during the operation of the collection device 80, for example.

[0041] The air flow generation device 82 generates an air flow for conveying (or carrying) the electrically-charged particles to the filter 81. The air flow generation device 82 may generate air circulation between the housing space 4 and the outside the housing 2. The air flow generation device 82 may include a fan, for example. The fan may be disposed inside an opening formed in the housing 2.

[0042] With reference to FIGS. 3 and 4, the charging device 83 may be an ionizer including a filter-charging unit 84 charging the filter 81 , a particle-charging unit 85 charging particles 5 in order to form electrically-charged particles 6 to be collected by the filter 81 , and a power source 86.

[0043] The filter-charging unit 84, for example, includes a filter-charging anode electrode (a first electrode) 91 and a pair of filter-charging cathode electrodes 92. The filter-charging anode electrode 91 and the pair of filter charging cathode electrodes 92 are formed of stainless steel, as an example. [0044] With reference to FIGS. 3 to 5, the filter-charging anode electrode 91 is connected to the power source 86. A high voltage is applied to the filter- charging anode electrode 91 by the power source 86. The filter-charging anode electrode 91 includes a plurality of needle electrodes 95. The needle electrodes 95 may be disposed in parallel at regular intervals. The needle electrode 95 has a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of filter-charging cathode electrodes 92 are grounded, and are disposed to face each other. The filter-charging anode electrode 91 is disposed between the pair of filter-charging cathode electrodes 92. The configuration of the filter charging unit 84 is not limited to the example of FIGS. 3 and 4, and can be suitably changed.

[0045] With reference to FIGS. 3 and 4, in the filter-charging unit 84, in a case where a voltage applied to the filter-charging anode electrode 91 is less than a predetermined value, no current flows between the filter-charging anode electrode 91 and the pair of filter-charging cathode electrodes 92. Flowever, in a case where a voltage applied to the filter-charging anode electrode 91 is equal to or greater than the predetermined value, a discharge phenomenon occurs, causing a current to flow between the filter-charging anode electrode 91 and the pair of filter-charging cathode electrodes 92. In the filter-charging unit 84, filter charging ions (first ions) are emitted from the plurality of needle electrodes 95 by the current. A current amount (a current-carrying amount) flowing between the filter-charging anode electrode 91 and the pair of filter-charging cathode electrodes 92 increases as a voltage applied to the filter-charging anode electrode 91 increases, thereby also increasing an emission amount of the filter charging ions emitted from the plurality of needle electrodes 95.

[0046] The filter-charging ions charge the filter 81 to collect the electrically- charged particles 6 via static electricity. When the filter 81 is set to collect the electrically-charged particles 6 via negative static electricity, the filter-charging ions are negative ions. The filter-charging ions are emitted from each of the plurality of needle electrodes 95 in a direction that the needle electrode 95 points to. The direction that the needle electrode 95 points to is a direction in which the needle electrode 95 protrudes, for example toward the left in FIG. 4. That is, the filter-charging anode electrode 91 includes a first emission direction in which the filter-charging ions are emitted, corresponding to the direction that the needle electrode 95 points to.

[0047] According to examples, the particle-charging unit 85 may include a particle-charging anode electrode (a second electrode) 93 and a pair of particle charging cathode electrodes 94. The particle-charging anode electrode 93 and the pair of particle-charging cathode electrodes 94 may be formed of stainless steel, as an example.

[0048] Still with reference to FIGS. 3 to 5, the particle-charging anode electrode 93 is connected to the power source 86. A high voltage is applied to the particle-charging anode electrode 93 by the power source 86. The particle charging anode electrode 93 includes a plurality of needle electrodes 96. The needle electrodes 96 may be disposed in parallel at regular intervals. The needle electrode 96 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of particle-charging cathode electrodes 94 are grounded, and are disposed to face each other. The particle-charging anode electrode 93 is disposed between the pair of particle-charging cathode electrodes 94. The configuration of the particle-charging unit 85 is not limited to the example of FIGS. 3 and 4, and can be suitably changed.

[0049] In the particle-charging unit 85, in a case where a voltage applied to the particle-charging anode electrode 93 is less than a predetermined value, no current flows between the particle-charging anode electrode 93 and the pair of particle-charging cathode electrodes 94. Flowever, in a case where a voltage applied to the particle-charging anode electrode 93 is equal to or greater than the predetermined value, a discharge phenomenon occurs, causing a current to flow between the particle-charging anode electrode 93 and the pair of particle charging cathode electrodes 94. In the particle-charging unit 85, particle-charging ions (second ions) are emitted from the plurality of needle electrodes 96 by the current. A current amount (a current-carrying amount) flowing between the particle-charging anode electrode 93 and the pair of particle-charging cathode electrodes 94 increases as a voltage applied to the particle-charging anode electrode 93 increases, thereby also increasing an emission amount of the particle-charging ions emitted from the plurality of needle electrodes 96.

[0050] The particle-charging ions charge the particles 5, in order to form the electrically-charged particles 6. When the filter 81 is set to collect the electrically-charged particles 6 via negative static electricity, the particle-charging ions are positive ions, so as to positively charge the particles 5 and thereby form the electrically-charged particles 6. The particle-charging ions are emitted from each of the plurality of needle electrodes 96 in a direction that the needle electrode 96 points to. The direction that the needle electrode 96 points to is a direction in which the needle electrode 96 protrudes, for example toward the right in FIG. 4. That is, the particle-charging anode electrode 93 includes a second emission direction in which the particle-charging ions are emitted, corresponding to the direction that the needle electrode 96 points to.

[0051] With reference to FIGS. 1 , 2, and 4, an air flow channel 8 formed in the housing space 4, directs an air flow 7 generated by the air flow generation device 82. The air flow channel 8 forms a route for discharging the air of the housing space 4 to the outside of the housing 2 to convey (or carry) the particles 5 floating in the housing space 4 to the filter 81. The air flow channel 8 may be defined by a flow channel forming member such as a duct, in some examples or may be a flow channel formed within the housing space 4 by one or more other components without being defined by a single flow channel forming member. When the air flow channel 8 is defined by the flow channel forming member such as a duct, it is possible to efficiently generate the air flow 7. A plurality of air flow channels 8 may be formed in the housing space 4. In some examples, the airflow channel 8 may diverge into the plurality of channels, and in other examples, the plurality of airflow channels 8 may converge. Accordingly, in the drawings, a line indicating the outer edge of the air flow channel 8 may represent a boundary of an example flow channel forming member such as a duct according to some examples, or may schematically represent the boundary of the air flow channel 8 otherwise formed in the housing space 4 according to other examples.

[0052] In the air flow channel 8, the particle-charging unit 85, the filter charging unit 84, and the filter 81 are disposed in this order, along the direction of the air flow 7. That is, in the direction of the air flow 7, the filter-charging unit 84 including the filter-charging anode electrode 91 is disposed upstream the filter 81 , and the particle-charging unit 85 including the particle-charging anode electrode 93 is disposed upstream the filter-charging unit 84 of the filter-charging anode electrode 91. The air flow generation device 82 may be disposed at any suitable position of the air flow channel 8. In some examples, the air flow generation device 82 may be disposed downstream the filter 81 in the direction of the air flow 7.

[0053] The filter-charging unit 84 is disposed such that the plurality of needle electrodes 95 of the filter-charging anode electrode 91 point toward the filter 81 . Namely, the plurality of needle electrodes 95 may point downstream in the direction of the air flow 7, so that the first emission direction of the filter charging anode electrode 91 in which the filter-charging ions are emitted, points toward the filter 81 . Accordingly, a voltage is applied to the filter-charging anode electrode 91 , so that the filter-charging ions are emitted from the plurality of needle electrodes 95 toward the filter 81 . Consequently, the surface of the filter 81 is charged by the filter-charging ions. In some examples, the surface of the filter 81 to be charged, may not be charged beforehand, or in other examples, the surface of the filter 81 may be charged beforehand such that the filter charging ions further charge the surface of the filter 81 .

[0054] In addition, the particle-charging unit 85 is disposed such that the plurality of needle electrodes 96 of the particle-charging anode electrode 93 point away from the filter 81 . Namely, the plurality of needle electrodes 96 may point upstream in the direction of the air flow 7 so that the second emission direction of the particle-charging anode electrode 93 in which the particle-charging ions are emitted, points toward a side counter to the filter 81 (e.g., a side of the particle charging anode electrode 93 that is opposite to the filter 81 ). Accordingly, a voltage is applied to the particle-charging anode electrode 93, so that the particle charging ions are emitted from the plurality of needle electrodes 96 away from the filter 81. Consequently, the particles 5 carried in the air flow 7 of the air flow channel 8 are charged by the particle-charging ions to become the electrically- charged particles 6, and so that the electrically-charged particles 6 are collected by the filter 81 .

[0055] With reference to FIGS. 2 to 4, the controller 70 may control a power supply 86 of the charging device 83 to selectively switch between applying a voltage to the filter-charging anode electrode 91 and applying a voltage to the particle-charging anode electrode 93. That is, the power source 86 may be operated in a first mode to apply a voltage to the filter-charging anode electrode 91 exclusively, so as to not apply any voltage to the particle-charging anode electrode 93 while applying a voltage to the filter-charging anode electrode 91 , and in a second mode to a voltage to the particle-charging anode electrode 93 exclusively, so as to not apply any voltage to the filter-charging anode electrode 91 while applying a voltage to the particle-charging anode electrode 93.

[0056] The power source 86 may apply a voltage either to the filter charging anode electrode 91 or to the particle-charging anode electrode 93 at a selected arbitrary timing, without continuously (or constantly) applying a voltage to the filter-charging anode electrode 91 or the particle-charging anode electrode 93. For example, the controller 70 may control the power source 86 to apply a voltage to the particle-charging anode electrode 93 at a selected time for collecting the particles 5 floating in the housing space 4. In addition, the controller 70 may control the power source 86 to apply a voltage to the filter-charging anode electrode 91 at a selected time for charging the filter 81 . The controller 70 may further operate the air flow generation device 82 selectively at the time of applying the voltage to the filter-charging anode electrode 91 or at the time of applying the voltage to the particle-charging anode electrode 93. The controller 70 may further operate the air flow generation device 82 at a timing when no voltage is applied to either the filter-charging anode electrode 91 or the particle-charging anode electrode 93.

[0057] However, a surface potential of the filter 81 decreases as the cumulative number of sheets printed by the imaging apparatus 1 increases. When the surface potential of the filter 81 decreases, a collection rate of the filter 81 also decreases. Therefore, the controller 70 may determine a timing for applying a voltage to the filter-charging anode electrode 91 , based on the surface potential of the filter 81 and/or the cumulative number of printed sheets of the imaging apparatus 1 . For example, with reference to FIG. 6, when the surface potential of the filter 81 is less than a predetermined threshold potential, the controller 70 may control the power source 86 to apply a voltage to the filter- charging anode electrode 91 , in order to charge the filter 81. The surface potential of the filter 81 can be obtained, for example, from a measurement device that may be connected to the filter 81 . In addition, when the cumulative number of printed sheets of the imaging apparatus 1 is greater than a predetermined threshold number, the controller 70 may control the power source 86 to apply a voltage to the filter-charging anode electrode 91 , in order to charge the filter 81. The cumulative number of printed sheets of the imaging apparatus 1 , for example, can be obtained from log information of the imaging apparatus 1.

[0058] In the operation of the imaging apparatus 1 , the fixing device 50 generates particles from evaporative substances that vaporize due to an increase in the temperature of the fixing device 50. Accordingly, the generation of the particles is accelerated as a use temperature (or an operation temperature) of the fixing device 50 increases, and the generation of the particles is suppressed as the use temperature of the fixing device 50 decreases. The use temperature of the fixing device 50 may correspond to the highest temperature of the fixing device 50 or to a temperature of the fixing device 50 that exceeds a threshold. Additionally, the electrically-charged particles 6 are trapped by the filter 81 , and thus, the surface potential of the filter 81 decreases. For this reason, the surface potential of the filter 81 decreases as the particles generated increases. Therefore, the controller 70 may determine a charging cycle for applying a voltage to the filter-charging anode electrode 91 , based on the use temperature of the fixing device 50. An example charging cycle defined by an interval between consecutive charging timings, is illustrated in FIG. 6 (based on the number of printed sheets). Additionally, with reference to FIG. 7, the controller 70 may shorten the charging cycle as the use temperature of the fixing device 50 increases, or may lengthen (increase the length of) the charging cycle as the use temperature of the fixing device 50 decreases.

[0059] In the example collection device 80, a charging amount of the filter 81 increases as a voltage value (a voltage number) applied to the filter-charging anode electrode 91 increases. In addition, in the filter-charging unit 84, the charging amount of the filter 81 increases as an applying time (or duration of application) of a voltage applied to the filter-charging anode electrode 91 is increased. On the other hand, as described above, the surface potential of the filter 81 decreases as the cumulative number of printed sheets of the imaging apparatus 1 increases. In addition, the surface potential of the filter 81 decreases as the use temperature of the fixing device 50 increases. Therefore, the controller 70 may determine a voltage value to be applied to the filter-charging anode electrode 91 , and/or the duration of application (applying time) of a voltage to be applied to the filter-charging anode electrode 91 , based on at least one of the cumulative number of printed sheets of the imaging apparatus 1 and/or based on the use temperature of the fixing device 50. For example, the controller 70 may increase the voltage value to be applied to the filter-charging anode electrode 91 as the cumulative number of printed sheets of the imaging apparatus 1 increases, or may lengthen the duration of application of the voltage to be applied to the filter-charging anode electrode 91 . In addition, the controller 70 may lengthen the duration of application of the voltage to be applied to the filter-charging anode electrode 91 as the use temperature of the fixing device 50 increases.

[0060] Referring to FIG. 2, the charging device 83 in the collection device 80 is configured to charge the filter 81 , as described above. In the filter 81 , the static electricity weakens over time or the like, which decreases the collection rate of the electrically-charged particles, and a lifespan of the filter 81 may be prolonged by charging the filter 81 with the charging device 83. Accordingly, for example, a life cycle of the filter 81 may be extended, to reduce a maintenance cost for the imaging apparatus 1 .

[0061] In addition, the filter-charging ions are emitted from the filter charging anode electrode 91 of the charging device 83, to more easily charge the filter 81 by the filter-charging ions.

[0062] In addition, the plurality of needle electrodes 95 of the filter-charging anode electrode 91 point toward the filter 81 , to emit the filter-charging ions from each of the needle electrodes 95 to the filter 81 , so as to suitably charge the filter 81.

[0063] In addition, the particle-charging anode electrode 93 (the particle charging unit 85), the filter-charging anode electrode 91 (the filter-charging unit 84), and the filter 81 are arranged in this order in the direction of the air flow 7. Consequently, the particles 5 carried in the air flow through the air flow channel 8 are charged by the particle-charging ions, so as to form the electrically-charged particles 6, and thus, can be collected by the filter 81 charged by the filter charging ions.

[0064] In addition, the plurality of needle electrodes 96 of the particle charging anode electrode 93 points away from the filter 81 , to emit the particle charging ions from each of the plurality of needle electrodes 96 away from the filter 81 so as to suppress the neutralization of the filter 81 due to the particle charging ions emitted.

[0065] FIG. 8 is a block diagram of a collection device 80A of another example. The example collection device 80A may replace the collection device 80 in the imaging apparatus 1 illustrated in FIG. 1. As illustrated in FIG. 8, the collection device 80A may include the filter 81 , the air flow generation device 82, and a charging device 83A.

[0066] With further reference to FIGS. 9 and 10, the charging device 83A, for example, is an ionizer including a filter-charging portion 84A to charge the filter 81 , a particle-charging portion 85A to charge the particles so as to generate the electrically-charged particles to be collected by the filter 81 , and a power source 86A.

[0067] The filter-charging portion 84A may include a part of an anode electrode 111 and a pair of filter-charging cathode electrodes (first opposite electrodes) 112. The particle-charging portion 85A, for example, includes a part of an anode electrode 111 and a pair of particle-charging cathode electrodes (second opposite electrodes) 114. The anode electrode 111 is also capable of emitting either types of ions among the filter-charging ions (the first ions) for charging the filter 81 and the particle-charging ions (the second ions) for forming the electrically-charged particles to be collected, by changing the polarity of a voltage applied to the anode electrode 111. Namely, the anode electrode 111 is a single electrode that can emit both the filter-charging ions and the particle charging ions. The anode electrode 111 is disposed over both of the filter charging portion 84A and the particle-charging portion 85A, and is connected to the power source 86A. A high voltage is applied to the anode electrode 111 by the power source 86A. The anode electrode 111 , the pair of filter-charging cathode electrodes 112, and the pair of particle-charging cathode electrodes 114 are formed of stainless steel, as an example.

[0068] The anode electrode 111 includes a plurality of needle electrodes 115 (first electrode portions). The needle electrodes 115 may be disposed in parallel at regular intervals. The needle electrode 115 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of filter charging cathode electrodes 112 are grounded via a switch 117, and are disposed to face each other. The plurality of needle electrodes 115 are disposed between the pair of filter-charging cathode electrodes 112. The configuration of the filter charging portion 84A is not limited to the example of FIGS. 9 and 10, and can be suitably changed.

[0069] In the particle-charging portion 85A, the anode electrode 111 includes a plurality of needle electrodes 116 (second electrode portions). The plurality of needle electrodes 116, for example, are disposed in parallel at regular intervals. The needle electrode 116 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of particle-charging cathode electrodes 114 are grounded via the switch 117, and are disposed to face each other. The plurality of needle electrodes 116 are disposed between the pair of particle-charging cathode electrodes 114. The configuration of the particle charging portion 85A is not limited to the example of FIGS. 9 and 10, and can be suitably changed.

[0070] The filter-charging ions are emitted from each of the plurality of needle electrodes 115 in a direction that the needle electrode 115 points to. The direction that the needle electrode 115 points to is a direction in which the needle electrode 115 protrudes. That is, the anode electrode 111 includes a first emission direction in which the filter-charging ions are emitted, corresponding to the direction that the needle electrode 115 points to. The particle-charging ions are emitted from each of the plurality of needle electrodes 116 in a direction that the needle electrode 116 points to. The direction that the needle electrode 116 points to is a direction in which the needle electrode 116 protrudes. That is, the anode electrode 111 includes a second emission direction in which the particle-charging ions are emitted, corresponding to the direction that the needle electrode 116 points to.

[0071] The switch 117 is an electrical circuit component selectively grounding either the pair of filter-charging cathode electrodes 112 or the pair of particle-charging cathode electrodes 114. Namely, the switch 117 does not ground the pair of particle-charging cathode electrodes 114 while grounding the pair of filter-charging cathode electrodes 112. On the other hand, the switch 117 does not ground the pair of filter-charging cathode electrodes 112 while grounding the pair of particle-charging cathode electrodes 114.

[0072] In the filter-charging portion 84A, when the pair of filter-charging cathode electrodes 112 are grounded by the switch 117, and a voltage that is equal to or greater than a predetermined value is applied to the anode electrode 111 , a discharge phenomenon occurs, and a current flows between the anode electrode 111 and the pair of filter-charging cathode electrodes 112, such that the current causes the plurality of needle electrodes 115 to emit the filter-charging ions. An amount of current (current amount) flowing between the anode electrode 111 and the pair of filter-charging cathode electrodes 112 increases as a voltage applied to the anode electrode 111 increases, thereby also increasing an emission amount of the filter-charging ions emitted from the plurality of needle electrodes 115. The filter-charging ions are emitted from each of the plurality of needle electrodes 115 in the direction that the needle electrode 115 points to, which corresponds to a direction in which the needle electrode protrudes.

[0073] In the particle-charging portion 85A, when the pair of particle charging cathode electrodes 114 are grounded by the switch 117, and a voltage that is equal to or greater than to a predetermined value is applied to the anode electrode 111 , a discharge phenomenon occurs, and a current flows between the anode electrode 111 and the pair of particle-charging cathode electrodes 114, such that the current causes the plurality of needle electrodes 116 to emit the particle-charging ions. An amount of current (current amount) flowing between the anode electrode 111 and the pair of particle-charging cathode electrodes 114 increases as a voltage applied to the anode electrode 111 increases, thereby also increasing an emission amount of the particle-charging ions emitted from the plurality of needle electrodes 116. The particle-charging ions are emitted from each of the plurality of needle electrodes 116 in the direction that the needle electrode 116 points to, which corresponds to a direction in which the needle electrode 116 protrudes.

[0074] An insulator 118 may be disposed between each of the pair of filter charging cathode electrodes 112 and each of pair of particle-charging cathode electrodes 114. The insulator 118 insulates the pair of filter-charging cathode electrodes 112 and the pair of particle-charging cathode electrodes 114. When the pair of filter-charging cathode electrodes 112 are grounded by the switch 117, the insulator 118 prevents a current from flowing between the anode electrode 111 and the pair of particle-charging cathode electrodes 114. In addition, when the pair of particle-charging cathode electrodes 114 are grounded by the switch 117, the insulator 118 prevents a current from flowing between the anode electrode 111 and the pair of filter-charging cathode electrodes 112. In some examples, a resin-based material such as a rubber is used as the insulator 118. [0075] With reference FIGS. 1 , 9, and 10, an air flow channel 8A formed in the housing space 4, directs an air flow 7A generated by the air flow generation device 82. The air flow channel 8A forms a route for discharging the air of the housing space 4 to the outside of the housing 2 to convey (or carry) the particles 5 floating in the housing space 4 to the filter 81 . In the air flow channel 8A, the particle-charging portion 85A, the filter-charging portion 84A, and the filter 81 are disposed in this order, along the direction of the air flow 7A. Accordingly, in the direction of the airflow 7A, the filter-charging portion 84A including the plurality of needle electrodes 115 is disposed upstream the filter 81 , and the particle-charging portion 85A including the plurality of needle electrodes 116 is disposed upstream the filter-charging portion 84A including the plurality of needle electrodes 115. The air flow generation device 82 may be disposed at any suitable position of the air flow channel 8A. In some examples, the air flow generation device 82 may be disposed downstream the filter 81 in the direction of the air flow 7.

[0076] The anode electrode 111 is disposed such that the plurality of needle electrodes 115 of the filter-charging portion 84A point toward the filter 81 and the plurality of needle electrodes 116 of the particle-charging portion 85A point away from the filter 81 . Namely, the plurality of needle electrodes 115 may point downstream in the direction of the air flow 7, so that the first emission direction of the anode electrode 111 in which the filter-charging ions are emitted, points toward the filter 81 . In addition, the plurality of needle electrodes 116 point away from the filter 81 , so that the second emission direction of the anode electrode 111 in which the particle-charging ions are emitted points away from the filter 81 . Namely, the plurality of needle electrodes 116 may point upstream in the direction of the air flow 7A so that the second emission direction of the anode electrode 111 in which the particle-charging ions are emitted, points toward a side counter to the filter 81 (e.g., a side of the anode electrode 111 that is opposite to the filter 81 ). Accordingly, when the pair of filter-charging cathode electrodes 112 are grounded by the switch 117, and a voltage is applied to the anode electrode 111 , the plurality of needle electrodes 115 emit the filter-charging ions toward the filter 81 . Consequently, the surface of the filter 81 is charged by the filter-charging ions. In addition, when the pair of particle-charging cathode electrodes 114 are grounded by the switch 117, and a voltage is applied to the anode electrode 111 , the plurality of needle electrodes 116 emits particle-charging ions away from the filter 81 , for example, toward the side counter to the filter 81. Consequently, the particles 5 carried in the air flow 7A of the air flow channel 8A are charged by the particle-charging ions to become the electrically-charged particles 6, and the electrically-charged particles 6 are collected by the filter 81 charged by the filter charging ions.

[0077] With reference to FIGS. 8 to 10, the controller 70 may control a power supply 86A of the charging device 83A such that the polarity of a voltage applied to the anode electrode 111 is selectively switched. In addition, the controller 70 controls the switch 117 such that the filter-charging cathode electrode 112 or the particle-charging cathode electrode 114 is selectively grounded. Namely, the controller 70 selectively switches between a first state in which the switch 117 grounds the pair of filter-charging cathode electrodes 112 and the power source 86A applies a negative voltage to the anode electrode 111 , and a second state in which the switch 117 grounds the pair of particle-charging cathode electrodes 114 and the power source 86A applies a positive voltage to the anode electrode 111 . The first state is a state in which the filter-charging ions are emitted from the plurality of needle electrodes 115. The second state is a state in which the particle-charging ions are emitted from the plurality of needle electrodes 116.

[0078] The controller 70 may switch between the first state and the second state, and may additionally operate in a neutral state so that the controller 70 is not set continuously (or constantly) to either the first state or the second state. According to examples, the controller 70 may set the first state or the second state at a selected timing. For example, the controller 70 may control the power source 86A and the switch 117 such that the second state is set at a selected time for collecting the particles 5 floating in the housing space 4. In addition, the controller 70 may control the power source 86A and the switch 117 such that the first state is set at a selected time for charging the filter 81 . The controller 70 may further operate the air flow generation device 82 selectively at the time of setting the first state or the second state. The controller 70 may further operate the air flow generation device 82 selectively in the neutral state when the controller 70 is neither set in the first state nor in the second state.

[0079] Referring to FIG. 8, the charging device 83A in the collection device 80A is configured to charge the filter 81 , as described above. In the filter 81 , the static electricity weakens over time or the like, which decreases the collection rate of the electrically-charged particles, and a lifespan of the filter 81 may be prolonged by charging the filter 81 with the charging device 83A. Accordingly, for example, the life cycle of the filter 81 may be extended, to reduce the maintenance cost for the imaging apparatus 1.

[0080] In addition, the filter-charging ions are emitted from the anode electrode 111 of the charging device 83A, to more easily charge the filter 81 by the filter-charging ions.

[0081] In addition, the plurality of needle electrodes 115 of the filter charging portion 84A point toward the filter 81 , to emit the filter-charging ions from each of the needle electrodes 115 to the filter 81 so as to suitably charge the filter 81.

[0082] In addition, the plurality of needle electrodes 116 of the particle- charging portion 85A point away from the filter 81 , to emit the particle-charging ions from each of the plurality of needle electrodes 116 away from the filter 81 , so as to suppress the neutralization of the filter 81 due to the particle-charging ions emitted.

[0083] FIG. 11 is a block diagram of a collection device 80B of another example. The example collection device 80B may replace the collection device 80 in the imaging apparatus 1 illustrated in FIG. 1. As illustrated in FIG. 11 , the collection device 80B may include the filter 81 , the air flow generation device 82, and a charging device 83B.

[0084] With further reference to FIG. 12, the charging device 83B, for example, is an ionizer including a charging unit 84B to charge the filter 81 and to charge the particles in order to form the electrically-charged particles to be collected by the filter 81 , a power source 86B, and a rotation actuator 87B.

[0085] The charging unit 84B may include an anode electrode 121 and a pair of cathode electrodes 122. The anode electrode 121 and the pair of cathode electrodes 122 are formed of stainless steel, as an example.

[0086] The anode electrode 121 is connected to the power source 86B. A high voltage is applied to the anode electrode 121 by the power source 86B. The anode electrode 121 is also capable of emitting either type of ions among the filter-charging ions (the first ions) for charging the filter 81 and the particle charging ions (the second ions) for forming the electrically-charged particles to be collected, by changing the polarity of a voltage applied to the anode electrode 121. Namely, the anode electrode 121 is a single electrode that can emit both the filter-charging ions and the particle-charging ions.

[0087] The anode electrode 121 includes a plurality of needle electrodes 123. The plurality of needle electrodes 123, for example, are disposed in parallel at regular intervals. The needle electrode 123 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of cathode electrodes 122 are grounded, and are disposed to face each other. The anode electrode 121 is disposed between the pair of cathode electrodes 122. The configuration of the charging unit 84B is not limited to the example of FIG. 12, and can be suitably changed. [0088] In the charging unit 84B, when a voltage that is equal to or greater than a predetermined value is applied to the anode electrode 121 , a discharge phenomenon occurs, and a current flows between the anode electrode 121 and the pair of cathode electrodes 122, such that the current causes the plurality of needle electrodes 123 to emit ions. An amount of current (a current amount or a current-carrying amount) flowing between the anode electrode 121 and the pair of cathode electrodes 122 increases as a voltage applied to the anode electrode 121 increases, thereby also increasing an emission amount of the ions emitted from the plurality of needle electrodes 123. The ions are emitted from each of the plurality of needle electrodes 123 in a direction that the needle electrode 123 points to, which corresponds to a direction in which the needle electrode 123 protrudes. Accordingly, the anode electrode 121 defines an emission direction which corresponds to the direction which the needle electrode 123 points to. Accordingly, the charging unit 84B may emit either types of ions among the filter charging ions and the particle-charging ions from the plurality of needle electrodes 123 by changing the polarity of a voltage applied to the anode electrode 121 .

[0089] The rotation actuator 87B rotates the charging unit 84B between a first position and a second position. The first position is a position in which the plurality of needle electrodes 123 point toward the filter 81 , so that the emission direction of the anode electrode 121 is set to emit the ions toward the filter 81. The second position is a position in which the plurality of needle electrodes 123 point away from the filter 81 so that the emission direction of the anode electrode 121 is set to emit the ions in a direction away from the filter 81 , for example toward a side counter to the filter 81 (e.g., a side of the anode electrode 121 that is opposite to the filter 81). The rotation actuator 87B may include a rotatable shaft to rotate about a rotation axis to which the charging unit 84B is attached, and a motor to rotate the rotatable shaft.

[0090] With reference to FIGS. 1 , 11 , and 12, an airflow channel 8B formed in the housing space 4, directs an airflow 7B generated by the airflow generation device 82. The air flow channel 8B forms a route for discharging the air of the housing space 4 to the outside of the housing 2 to convey (or carry) the particles 5 floating in the housing space 4 to the filter 81 . In the air flow channel 8B, the charging unit 84B, and the filter 81 are disposed in this order, along the direction of the airflow 7B. Accordingly, in the direction of the airflow 7B, the charging unit 84B including the plurality of needle electrodes 123 is disposed upstream the filter 81 . The air flow generation device 82 may be disposed at any suitable position of the air flow channel 8B. In some examples, the air flow generation device 82 may be disposed downstream the filter 81 in the direction of the air flow 7B. [0091] As illustrated in FIGS. 1 , 11 , and 12, the controller 70 controls the rotation actuator 87B such that the charging unit 84B is switched between the first position and the second position. In addition, the controller 70 controls a power supply of the charging device 83B such that the polarity of a voltage applied to the anode electrode 121 is selectively switched. Namely, the controller 70 may selectively switch between a first state in which the rotation actuator 87B sets the charging unit 84B to the first position such that the plurality of needle electrodes 123 point toward the filter 81 and the power source 86B applies a negative voltage to the anode electrode 121 , and a second state in which the rotation actuator 87B sets the charging unit 84B to the second position such that the plurality of needle electrodes 123 point away from the filter 81 and the power source 86B applies a positive voltage to the anode electrode 121. The first state is a state in which the filter-charging ions are emitted from the plurality of needle electrodes 123. The second state is a state in which the particle-charging ions are emitted from the plurality of needle electrodes 123.

[0092] Accordingly, when the controller 70 is switched to the first state, the filter-charging ions are emitted from the plurality of needle electrodes 123 toward the filter 81 , such that the surface of the filter 81 is charged by the filter-charging ions. In addition, when the controller 70 is switched to the second state, the particle-charging ions are emitted from the plurality of needle electrodes 123 away from the filter 81 , for example, toward a side counter to the filter 81 , such that the particles 5 carried in the air flow 7B of the air flow channel 8B are charged by the particle-charging ions to become the electrically-charged particles 6. The electrically-charged particles 6 are then collected by the filter 81 charged by the filter-charging ions. [0093] The controller 70 may switch between the first state and the second state, and may additionally operate in a neutral state so that the controller 70 is not set continuously (or constantly) to either the first state or the second state. According to examples, the controller 70 may set the first state or the second state at a selected timing. For example, the controller 70 may control the rotation actuator 87B and the power source 86B such that the second state is set at a selected time for collecting the particles 5 floating in the housing space 4. In addition, the controller 70 may control the rotation actuator 87B and the power source 86B such that the first state is set at a selected time for charging the filter 81 . The controller 70 may further operate the air flow generation device 82 selectively at the time of setting the first state or the second state. The controller 70 may further operate the air flow generation device 82 selectively in the neutral state when the controller 70 is neither set in the first state nor in the second state. [0094] Referring to FIG. 11 , the charging device 83B in the collection device 80B is configured to charge the filter 81 , as described above. In the filter 81 , the static electricity weakens over time or the like, which decreases the collection rate of the electrically-charged particles, and a lifespan of the filter 81 may be prolonged by charging the filter 81 with the charging device 83B. Accordingly, for example, the life cycle of the filter 81 may be extended, to reduce the maintenance cost of the imaging apparatus 1.

[0095] In addition, the filter-charging ions are emitted from the anode electrode 121 of the charging device 83B, to more easily charge the filter 81 by the filter-charging ions.

[0096] In addition, the controller 70 may control the rotation actuator 87B and the power source 86B to set the first state, in order to emit the filter-charging ions from the plurality of needle electrodes 123 pointing toward the direction of the filter 81 to the filter 81 , so as to suitably charge the filter 81 .

[0097] In addition, the controller 70 may control the rotation actuator 87B and the power source 86B to set the second state, in order to emit the particle charging ions from the plurality of needle electrodes 123 pointing in a direction away from the filter 81 , so as to suppress the neutralization of the filter 81 due to the particle-charging ions. [0098] FIG. 13 is a block diagram of a collection device 80C of another example. The example collection device 80C may replace the collection device 80 in the imaging apparatus 1 illustrated in FIG. 1. As illustrated in FIG. 13, the collection device 80C may include the filter 81 , the air flow generation device 82, and a charging device 83C.

[0099] With further reference to FIG. 14, the charging device 83C, for example, is an ionizer including a filter-charging unit 84C to charge the filter 81 , a particle-charging unit 85C to charge the particles in order to form the electrically- charged particles to be collected by the filter 81 , a power source 86C, and a power source 87C.

[00100] The filter-charging unit 84C may include a filter-charging anode electrode (a first electrode) 131 and a pair of filter-charging cathode electrodes 132. The filter-charging anode electrode 131 and the pair of filter-charging cathode electrodes 132 are formed of stainless steel, as an example.

[00101] The filter-charging anode electrode 131 is connected to the power source 86C. A high voltage is applied to the filter-charging anode electrode 131 by the power source 86C. The filter-charging anode electrode 131 includes a plurality of needle electrodes 135. The plurality of needle electrodes 135, for example, are disposed in parallel at regular intervals. The needle electrode 135 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of filter-charging cathode electrodes 132 are grounded, and are disposed to face each other. The plurality of needle electrodes 135 are disposed between the pair of filter-charging cathode electrodes 132. The configuration of the filter-charging unit 84C is not limited to the example of FIG. 14, and can be suitably changed.

[00102] In the filter-charging unit 84C, when a voltage that is equal to or greater than to a predetermined value is applied to the filter-charging anode electrode 131 , a discharge phenomenon occurs, and a current flows between the filter-charging anode electrode 131 and the pair of filter-charging cathode electrodes 132, such that the current causes the plurality of needle electrodes 135 to emit the filter charging ions. An amount of current (current amount) flowing between the filter-charging anode electrode 131 and the pair of filter-charging cathode electrodes 132 increases as a voltage applied to the filter-charging anode electrode 131 increases, thereby also increasing an emission amount of the filter-charging ions emitted from the plurality of needle electrodes 135. The filter-charging ions are emitted from each of the plurality of needle electrodes 135 in a direction that the needle electrode 135 points to, which corresponds to a direction in which the needle electrode protrudes. Accordingly, the filter-charging anode electrode 131 defines a first emission direction which corresponds to the direction which the needle electrode 135 points to.

[00103] According to examples, the particle-charging unit 85C may include a particle-charging anode electrode (a second electrode) 133 and a pair of particle-charging cathode electrodes 134. The particle-charging anode electrode 133 and the pair of particle-charging cathode electrodes 134 may be formed of stainless steel, as an example.

[00104] The particle-charging anode electrode 133 is connected to the power source 87C. A high voltage is applied to the particle-charging anode electrode 133 by the power source 87C. The particle-charging anode electrode 133 includes a plurality of needle electrodes 136. The needle electrodes 136 may be are disposed in parallel at regular intervals. The needle electrode 136 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of particle-charging cathode electrodes 134 are grounded, and are disposed to face each other. The plurality of needle electrodes 136 are disposed between the pair of particle-charging cathode electrodes 134. The configuration of the particle-charging unit 85C is not limited to the example of FIG. 14, and can be suitably changed.

[00105] In the particle-charging unit 85C, when a voltage that is equal to or greater than a predetermined value is applied to the particle-charging anode electrode 133, a discharge phenomenon occurs, and a current flows between the particle-charging anode electrode 133 and the pair of particle-charging cathode electrodes 134 such that the current causes the plurality of needle electrodes 136 to emit the particle-charging ions. An amount of current (current amount) flowing between the particle-charging anode electrode 133 and the pair of particle charging cathode electrodes 134 increases as a voltage applied to the particle- charging anode electrode 133 increases, thereby also increasing an emission amount of the particle-charging ions emitted from the plurality of needle electrodes 136. The particle-charging ions are emitted from each of the plurality of needle electrodes 136 in a direction that the needle electrode 136 points to, which corresponds to a direction in which the needle electrode 136 protrudes. Namely, the particle-charging anode electrode 133 defines a second emission direction in which the particle-charging ions are emitted corresponding to the direction that the needle electrode 136 points toward.

[00106] With reference to FIGS. 1 , 13, and 14, an air flow channel 8C formed in the housing space 4, directs an air flow 7C generated by the air flow generation device 82. The air flow channel 8C forms a route for discharging the air of the housing space 4 to the outside of the housing 2 to convey (or carry) the particles 5 floating in the housing space 4 to the filter 81 . In the air flow channel 8C, the particle-charging unit 85C, the filter 81 , and the filter-charging unit 84C are disposed in this order, along the direction of the air flow 7C. Accordingly, in the direction of the air flow 7C, the particle-charging unit 85C including the plurality of needle electrodes 136 is disposed upstream the filter 81 , and the filter charging unit 84C including the plurality of needle electrodes 135 is disposed downstream the filter 81 . The air flow generation device 82 may be disposed at any suitable position of the air flow channel 8C. In some examples, the air flow generation device 82 may be disposed downstream the filter-charging unit 84C in the direction of the air flow 7C.

[00107] The filter-charging unit 84C is disposed such that the plurality of needle electrodes 135 of the filter-charging anode electrode 131 point toward the filter 81 , and the first emission direction of the filter-charging anode electrode 131 in which the filter-charging ions are emitted points toward the filter 81. Namely, the plurality of needle electrodes 135 may point upstream in the direction of the airflow 7C toward the filter 81 . Accordingly, when a voltage is applied to the filter charging anode electrode 131 , the filter-charging ions are emitted from the plurality of needle electrodes 135 toward the filter 81 , so as to charge the surface of the filter 81 with the filter-charging ions.

[00108] In addition, the particle-charging unit 85C is disposed such that the plurality of needle electrodes 136 of the particle-charging anode electrode 133 point away from the filter 81, and the second emission direction of the particle charging anode electrode 133 in which the particle-charging ions are emitted points away from the filter 81. Namely, the plurality of needle electrodes 136 may point upstream in the direction of the air flow 7C, such that the second emission direction of the particle-charging anode electrode 133 in which the particle charging ions are emitted points a side counter to the filter 81 (e.g., a side of the particle-charging anode electrode 133 that is opposite to the filter 81). Accordingly, when a voltage is applied to the particle-charging anode electrode 133, the particle-charging ions are emitted from the plurality of needle electrodes 136 away from the filter 81 , for example, toward the side counter to the filter 81. Consequently, the particles 5 carried in the air flow 7C of the air flow channel 8C are charged by the particle-charging ions to become the electrically-charged particles 6, and the electrically-charged particles 6 are collected by the filter 81 that has been charged by the filter-charging ions.

[00109] With reference to FIGS. 1, 13, and 14, the controller 70 may control a power supply of the charging device 83C such that a voltage is selectively applied to the filter-charging anode electrode 131 and to the particle-charging anode electrode 133, at selected timings. The controller 70 may operates the air flow generation device 82 at the time of applying a voltage to the filter-charging anode electrode 131 or to the particle-charging anode electrode 133. The controller 70 may further operate the air flow generation device 82 at a timing when no voltage is applied to either of the filter-charging anode electrode 131 or the particle-charging anode electrode 133.

[00110] According to examples, the filter-charging unit 84C is disposed downstream the filter 81 in the direction of the air flow 7C, so as to suppress the neutralization of the electrically-charged particles 6 due to the filter-charging ions even when the filter-charging ions are emitted from the plurality of needle electrodes 135 toward the filter 81 , before the electrically-charged particles 6 are collected by the filter 81.

[00111] Accordingly, the controller 70 may control the power supply of the charging device 83C such that a voltage is applied simultaneously to the filter- charging anode electrode 131 and to the particle-charging anode electrode 133. That is, the controller 70 may control the power source 86C and the power source 87C such that a voltage is applied to the filter-charging anode electrode 131 from the power source 86C and a voltage is applied to the particle-charging anode electrode 133 from the power source 87C, simultaneously.

[00112] As described above, in the collection device 80C illustrated in FIG. 13, the charging device 83C is configured to charge the filter 81. The static electricity in the filter 81 may weaken over time or the like, which decreases the collection rate of the electrically-charged particles, and a lifespan of the filter 81 may be prolonged by charging the filter 81 with the charging device 83C. Accordingly, for example, the life cycle of the filter 81 may be extended, to reduce the maintenance cost of the imaging apparatus 1.

[00113] In addition, the filter-charging ions are emitted from the filter charging anode electrode 131 of the charging device 83C, to more easily charge the filter 81 by the filter-charging ions.

[00114] In addition, the plurality of needle electrodes 135 of the filter charging unit 84C point toward the filter 81 , in order to emit the filter-charging ions from each of the plurality of needle electrodes 135 to the filter 81 , so as to suitably charge the filter 81 .

[00115] In addition, the plurality of needle electrodes 136 of the particle charging unit 85C point away from the filter 81 , to emit the particle-charging ions from each of the plurality of needle electrodes 136 away from the filter 81 so as to suppress the neutralization of the filter 81 due to the particle-charging ions emitted.

[00116] In addition, in the direction of the air flow 7C, the filter-charging unit 84C is disposed downstream the filter 81 , so as to charge the particles 5 to be collected by the filter 81 , even when a voltage is applied simultaneously to the filter-charging anode electrode 131 and to the particle-charging anode electrode 133. In addition, a voltage may be applied simultaneously to the filter-charging anode electrode 131 and to the particle-charging anode electrode 133, so as to suppress a decrease (or a significant decrease) in the charging amount of the filter 81 , even when a relatively long period of time has elapsed or when the number of printed sheets has increased.

[00117] FIG. 18 is a block diagram of a collection device 80G of another example. The example collection device 80G may replace the collection device 80 in the imaging apparatus 1 illustrated in FIG. 1. As illustrated in FIG. 18, the collection device 80G may include the filter 81 , the air flow generation device 82, and a charging device 83G.

[00118] With further reference to FIG. 19, the charging device 83G, for example, is an ionizer including a filter-charging unit 84G charge the filter 81 , a particle-charging unit 85G to charge the particles in order to form the electrically- charged particles to be collected by the filter 81 , and a power source.

[00119] The filter-charging unit 84G may include a filter-charging anode electrode (a first electrode) 141 and a pair of filter-charging cathode electrodes 142. The filter-charging anode electrode 141 and the pair of filter-charging cathode electrodes 142 are formed of stainless steel, as an example.

[00120] The filter-charging anode electrode 141 is connected to the power source. A high voltage is applied to the filter-charging anode electrode 141 by the power source. The filter-charging anode electrode 141 includes a plurality of needle electrodes 145. The plurality of needle electrodes 145, for example, are disposed in parallel at regular intervals. The needle electrode 145 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of filter-charging cathode electrodes 142 are grounded, and are disposed to face each other. The plurality of needle electrodes 145 are disposed between the pair of filter-charging cathode electrodes 142. The configuration of the filter charging unit 84G is not limited to the example of FIG. 19, and can be suitably changed.

[00121] In the filter-charging unit 84G, when a voltage that is equal to or greater than a predetermined value is applied to the filter-charging anode electrode 141 , a discharge phenomenon occurs, and a current flows between the filter-charging anode electrode 141 and the pair of filter-charging cathode electrodes 142, such that the current causes the plurality of needle electrodes 145 to emit filter charging ions. An amount of current (current amount) flowing between the filter-charging anode electrode 141 and the pair of filter-charging cathode electrodes 142 increases as a voltage applied to the filter-charging anode electrode 141 increases thereby also increasing an emission amount of the filter-charging ions emitted from the plurality of needle electrodes 145. The filter-charging ions are emitted from each of the plurality of needle electrodes 145 in a direction that the needle electrode 145 points to, which corresponds to a direction in which the needle electrode protrudes. Accordingly, the filter-charging anode electrode 141 defines a first emission direction which corresponds to the direction which the needle electrode 145 points to.

[00122] According to examples, the particle-charging unit 85G may include a particle-charging anode electrode (a second electrode) 143 and a pair of particle-charging cathode electrodes 144. The particle-charging anode electrode 143 and the pair of particle-charging cathode electrodes 144 may be formed of stainless steel, as an example.

[00123] The particle-charging anode electrode 143 is connected to the power source. A high voltage is applied to the particle-charging anode electrode 143 by the power source. The particle-charging anode electrode 143 includes a plurality of needle electrodes 146. The needle electrodes 146 may be disposed in parallel at regular intervals. The needle electrode 146 may have a pointed shape (e.g., formed to protrude into the shape of a needle or a blade). The pair of particle-charging cathode electrodes 144 are grounded, and are disposed to face each other. The plurality of needle electrodes 146 are disposed between the pair of particle-charging cathode electrodes 144. The configuration of the particle-charging unit 85G is not limited to the example of FIG. 19, and can be suitably changed.

[00124] In the particle-charging unit 85G, when a voltage that is equal to or greater than a predetermined value is applied to the particle-charging anode electrode 143, a discharge phenomenon occurs, and a current flows between the particle-charging anode electrode 143 and the pair of particle-charging cathode electrodes 144 such that the current causes the plurality of needle electrodes 146 to emit the particle-charging ions. An amount of current (current amount) flowing between the particle-charging anode electrode 143 and the pair of particle charging cathode electrodes 144 increases as a voltage applied to the particle- charging anode electrode 143 increases, thereby also increasing an emission amount of the particle-charging ions emitted from the plurality of needle electrodes 146. The particle-charging ions are emitted from each of the plurality of needle electrodes 146 in a direction that the needle electrode 146 points to, which corresponds to a direction in which the needle electrode 146 protrudes. Namely, the particle-charging anode electrode 143 defines a second emission direction in which the particle-charging ions are emitted corresponding to the direction that the needle electrode 146 points toward.

[00125] With reference to FIGS. 1 , 18, and 19, an air flow channel 8G formed in the housing space 4, directs an air flow 7G generated by the air flow generation device 82. Additionally, a region 147 for a filter charging unit is formed in the housing space 4. The air flow channel 8G forms a route for discharging the air of the housing space 4 to the outside of the housing 2 to convey (or carry) the particles 5 floating in the housing space 4 to the filter 81. The region 147 for the filter charging unit is a region disposed adjacent to the air flow channel 8G. [00126] In the air flow channel 8G, the particle-charging unit 85G and the filter 81 are disposed in this order, in the direction of the air flow 7G. Accordingly, in the direction of the air flow 7G, the particle-charging unit 85G including the plurality of needle electrodes 146 is disposed upstream the filter 81. The air flow generation device 82 may be disposed at any suitable position of the air flow channel 8G. In some examples, the air flow generation device 82 may be disposed downstream the filter 81 in the direction of the air flow 7G.

[00127] The region 147 for the filter charging unit is disposed in a position adjacent to the filter 81 . The filter-charging unit 84G is disposed in the region 147, so as to dispose the filter-charging unit 84G in a position adjacent to the filter 81 outside the air flow channel 8G. The filter-charging unit 84G may be disposed in the same position as that of the filter 81 in the direction of the air flow 7G according to some examples, on an upstream side of the filter 81 according to other examples, or on a downstream side of the filter 81 according to yet other examples.

[00128] According to examples, the air flow channel 8G may be defined by a flow channel forming member 148 such as a duct, and the region 147 for the filter charging unit may be defined by a shielding housing 149 disposed to cover a part of the flow channel forming member 148. In this case, the flow channel forming member 148 may include an opening, and the region 147 may communicate with the air flow channel 8G through the opening of the flow channel forming member 148. The examples may be modified. For example, the air flow channel 8G may not be defined by the flow channel forming member 148, and the region 147 may not be defined by the shielding housing 149.

[00129] The filter-charging unit 84G is disposed in the region 147 such that the plurality of needle electrodes 145 of the filter-charging anode electrode 141 point toward the filter 81 , and the first emission direction of the filter-charging anode electrode 141 in which the filter-charging ions are emitted points toward the filter 81. Accordingly, when a voltage is applied to the filter-charging anode electrode 141 , the filter-charging ions are emitted from the plurality of needle electrodes 145 toward the filter 81 , so as to charge the surface of the filter 81 with the filter-charging ions.

[00130] In addition, the particle-charging unit 85G is disposed such that the plurality of needle electrodes 146 of the particle-charging anode electrode 143 point away from the filter 81 , and the second emission direction of the particle charging anode electrode 143 in which the particle-charging ions are emitted, points away from the filter 81 . Namely, the plurality of needle electrodes 146 may point upstream in the direction of the air flow 7G, such that the second emission direction of the particle-charging anode electrode 143 in which the particle charging ions are emitted points toward a side counter to the filter 81 (e.g., a side of the particle-charging anode electrode 143 that is opposite to the filter 81). Accordingly, when a voltage is applied to the particle-charging anode electrode 143, the particle-charging ions are emitted from the plurality of needle electrodes 146 away from the filter 81 , for example, toward the side counter to the filter 81 . Consequently, the particles 5 carried in the air flow 7G of the air flow channel 8G are charged by the particle-charging ions, to become the electrically-charged particles 6, and the electrically-charged particles 6 are collected by the filter 81 charged by the filter-charging ions.

[00131] The controller 70 may control a power supply of the charging device 83G such that a voltage is selectively applied to the filter-charging anode electrode 141 and to the particle-charging anode electrode 143, at selected timings. The controller 70 operates the air flow generation device 82 at the time of applying a voltage to the filter-charging anode electrode 141 or to the particle charging anode electrode 143. The controller 70 may further operate the air flow generation device 82 at a timing when no voltage is applied to either of the filter charging anode electrode 141 or the particle-charging anode electrode 143, or may control the power supply of the charging device 83G such that a voltage is applied simultaneously to the filter-charging anode electrode 141 and to the particle-charging anode electrode 143. The filter-charging unit 84G is disposed in the position adjacent to the filter 81 outside the air flow channel 8G, so as to suppress the neutralization of the electrically-charged particles 6 due to the filter charging ions, even when the filter-charging ions are emitted from the plurality of needle electrodes 145 toward the filter 81 , before the electrically-charged particles 6 are collected by the filter 81 .

[00132] As described above, in the collection device 80G illustrated in FIG. 18, the charging device 83G is configured to charge the filter 81. The static electricity in the filter weakens over time or the like, which decreases the collection rate of the electrically-charged particles, and a lifespan of the filter 81 may be prolonged by charging the filter 81 with the charging device 83G. Accordingly, for example, the life cycle of the filter 81 may be extended, to reduce the maintenance cost of the imaging apparatus 1 .

[00133] In addition, the filter-charging ions are emitted from the filter charging anode electrode 141 of the charging device 83G, to more easily charge the filter 81 by the filter-charging ions.

[00134] In addition, the plurality of needle electrodes 145 of the filter charging unit 84G point toward the filter 81 , in order to emit the filter-charging ions from each of the plurality of needle electrodes 145 to the filter 81 , so as to suitably charge the filter 81 .

[00135] In addition, the plurality of needle electrodes 146 of the particle charging unit 85G point away from the filter 81 , to emit the particle-charging ions from each of the plurality of needle electrodes 146 away from the filter 81 so as to suppress the neutralization of the filter 81 due to the particle-charging ions emitted.

[00136] In addition, the filter-charging unit 84G is disposed in the position adjacent to the filter 81 outside the air flow channel 8G, so as to charge the particles 5 to be collected by the filter 81 , even when a voltage is applied simultaneously to the filter-charging anode electrode 141 and the particle charging anode electrode 143. A voltage may be applied simultaneously to the filter-charging anode electrode 141 and the particle-charging anode electrode 143, so as to suppress a decrease or a significant decrease in the charging amount of the filter 81 , even when a relatively long period of time has elapsed or when the number of printed sheets has increased.

[00137] In addition, the filter-charging unit 84G is disposed outside the air flow channel 8G, in order to suppress the inhibition of the air flow 7G due to the filter-charging unit 84G, and thereby suppress a pressure loss of the air flow 7G, and better achieve a suitable flow rate of the air flow 7G.

[00138] Although various examples have been described herein, it is to be understood that the examples can be modified in disposition, configuration and details.

[00139] For example, in a case where the particles are charged in advance, when the particles are charged by other devices, or the like, as illustrated in FIG.

15, the charging device may include a function or a device for emitting the particle charging ions. In addition, when it is possible to generate the air flow in the air flow channel by other devices, the collection device may not include the air flow generation device. The charging device 83D illustrated in FIG. 15 includes a filter charging unit 84D corresponding to the filter-charging unit 84 illustrated in FIGS. 3 and 4, and a power source (not illustrated). As with the filter-charging unit 84 illustrated in FIGS. 3 and 4, the filter-charging unit 84D includes a filter-charging anode electrode 91 D including a plurality of needle electrodes 95D, and a pair of filter-charging cathode electrodes 92D. According to examples, a voltage may be applied to the filter-charging anode electrode 91 D at a selected timing, without applying the voltage continuously (or constantly). The charging device 83D may have a configuration different from the particle-charging unit 85 illustrated in FIGS. 3 and 4.

[00140] According to such a configuration, the charging device 83D emits the filter-charging ions, to charge the filter 81 and to collect the electrically- charged particles 6 carried in the air flow 7D of the air flow channel 8D by the filter 81 . The static electricity in the filter 81 tends to weaken over time or the like, such that the collection rate of the electrically-charged particles decreases, and the filter 81 may be used for a longer period of time by charging the filter 81 with the charging device 83D. Accordingly, the life cycle of the filter 81 may be extended, to reduce the maintenance cost of the imaging apparatus 1 .

[00141] In addition, for example, a charging device 83E as illustrated in FIG. 16 can be used as another configuration of the charging device for emitting ions in a predetermined emission direction. The charging device 83E illustrated in FIG.

16 includes an anode electrode 91 E extending in the shape of a wire, and a cathode electrode 92E disposed to partially surround the anode electrode 91 E. The anode electrode 91 E extends in a direction intersecting with the air flow, for example, a direction orthogonal to the air flow. The cathode electrode 92E surrounds the anode electrode 91 E around an axis line of the anode electrode 91 E, and is in a shape in which a part around the axis line of the anode electrode 91 E is opened. Accordingly, when the cathode electrode 92E is grounded, a voltage may be applied to the anode electrode 91 E, so that the anode electrode 91 E emits ions, and the ions are emitted in a direction of the opening of the cathode electrode 92E with respect to the anode electrode 91 E. Accordingly, the direction of the opening of the cathode electrode 92E with respect to the anode electrode 91 E is an emission direction in which the ions are emitted. The electrode of the charging device in any of the above-described examples may be replaced with such an electrode of the charging device 83E.

[00142] In addition, for example, a charging device 83F as illustrated in FIG.

17 can be used as another configuration of the charging device to charge the filter. The charging device 83F illustrated in FIG. 17 is a device for charging the filter 81 by friction or charge injection. The charging device 83F, for example, may rub the surface of the filter 81 with a resin brush to as to charge the filter 81 by friction. In addition, the charging device 83F may apply a voltage to a magnetic brush in contact with the surface of the filter 81 so as to charge the filter 81 by charge injection. The charging device in any of the above-described examples may be replaced with such a charging device 83F.

[00143] It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted.