BACKGROUND

[0001] A scanner irradiates light onto a document by using an illumination device, forms an image based on light reflected from the document onto an image sensor by using imaging optics, and obtains image data through photoelectric conversion of an optical image formed on the image sensor into an electrical signal. The image sensor is a linear 1 -dimensional image sensor having a length in a first direction. 1 -dimensional images may be continuously read by using the image sensor while moving a scan module in a second direction. The read image data may be converted to a 2-dimensional image through image processing.

[0002] To obtain color image data, two methods may be employed. One method irradiates white light onto a document by using an illumination device, color-separates light reflected from the document into light of R, G, and B colors, and receives the light of the R, G, and B colors through R, G, B sensing regions on a color image sensor, respectively. The other method sequentially irradiates light of three colors, that is, R, G, and B onto a document by using an illumination device and sequentially receives the light of three colors by using a monochrome image sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] FIG. 1 is a schematic view of a scanner according to an example.

[0004] FIG. 2 is a schematic view of a scanner according to another example. [0005] FIG. 3 is a perspective view of an example of a illumination device employed in the scanners shown in FIGS. 1 and 2.

[0006] FIG. 4 is a side view of a light guiding member of the example shown in FIG. 3.

[0007] FIG. 5 is a graph simulating illumination characteristics on a document surface in a first direction according to a change of a distance between a document and a document tray, according to an example.

[0008] FIG. 6 is a lateral view of one example of a light guiding member.

[0009] FIG. 7 is a lateral view of one example of a light guiding member.

[0010] FIG. 8 is a lateral view of one example of a light guiding member.

[0011] FIG. 9 is a lateral view of one example of a light guiding member.

[0012] FIG. 10 is a lateral view of one example of a light guiding member.

[0013] FIG. 11 is a lateral view of one example of a light guiding member.

DETAILED DESCRIPTION

[0014] FIG. 1 is a schematic view of a scanner according to an example. Referring to FIG. 1 , a document tray 200 on which a document 1 is placed and an image reading module 100 are shown. The image reading module 100 irradiates light onto an object e.g., the document 1 placed on the document tray 200, to read image information therefrom, receives light reflected from the document 1 , and photoelectrically converts the reflected light. The image reading module 100 may include an illumination device 110 for irradiating light onto the document 1 , an image sensor 120, and imaging optics 130 for imaging light reflected from the document 1 onto the image sensor 120.

[0015] The illumination device 110 may sequentially irradiate light of R (red), G (green), and B (blue) colors onto the document 1 for color scanning. Light emitted from the illumination device 110 to the document 1 passes through the imaging optics 130 and is incident on the image sensor 120. The image sensor 120 converts an optical signal into an electrical signal through photoelectric conversion. The image sensor 120 may be, for example, a charge coupled device (CCD) image sensor, a complementary metal-oxide semiconductor (CMOS) image sensor, etc. In this example, the image sensor 120 is a monochromatic sensor.

[0016] The image sensor 120 may be a linear image sensor having a length in a first direction M. To obtain 2-dimensional image data, at least one of the illumination device 110, the imaging optics 130, and the image sensor 120 may be moved in a second direction S. Hereinafter, the first direction M refers to the width-wise direction of the document 1 , and the second direction S refers to the length-wise direction of the document 1. The second direction S is orthogonal to the first direction M. In this example, the image reading module 100 including the illumination device 110, the image forming optics 130, and the image sensor 120 is moved or moves in the second direction S. In this example, the length of the image sensor 120 in the first direction M is smaller than the length of the document 1 in the first direction M. Therefore, the imaging optics 130 may be a reduction imaging optics for reducing light reflected from the document 1 in the first direction M and forming an image thereof on the image sensor 120. The imaging optics 130 may include one or more lenses.

[0017] The document tray 200 may include a photo-transmissive reading region 210 on which the document 1 is placed and a shading correction region 220. The photo-transmissive reading region 210 may include a photo-transmissive material (e.g., glass) through which light may be transmitted. The shading correction region 220 is located on the second direction S side of the reading region 210. The image reading module 100 may be located in the shading correction region 220 when the image reading module is not performing a scanning operation. The image reading module 100 being located in the shading correction region 220 indicates that at least a light transmitting window 112 through which illumination light and light reflected from the document 1 pass is located out of the reading region 210 and is in the shading correction region 220. The shading correction region 220 may be provided with a shading correction sheet 500, which serves as a reference for shading correction. The shading correction sheet 500 may be read by the image reading module 100 when the image reading module 100 moves from the shading correction region 220 to the reading region 210.

[0018] The scanner may include an upper cover 300 that covers the photo-transmissive reading region 210. The upper cover 300 may be rotated around a hinge 301 between a position for exposing an upper portion of the photo-transmissive reading region 210 to place the document 1 on the photo-transmissive reading region 210 and a position for covering the photo-transmissive reading region 210.

[0019] When a scan start signal is input from a host (not shown) or an operation panel (not shown) of a scanner, the image reading module 100 is moved or moves in the second direction S and performs a scanning operation. An optical signal reflected from the document 1 and an image thereof formed on the image sensor 120 by the imaging optics 130 is photoelectrically converted by the image sensor 120 into an electrical signal. The electrical signal is converted into a digital value by an analog/digital (A/D) converter (not shown). An image processing unit (not shown) may generate image data from the digital value and store the same in a storage unit (e.g., a memory (not shown)) or output to an external device (not shown), e.g., a printer, a host device, etc.

[0020] FIG. 2 is a schematic view of a scanner according to an example. Unlike the example of the scanner shown in FIG. 1 , the scanner of this example includes an image reading module 100a in the form of a contact image sensor (CIS) module. Therefore, members having the same functions are denoted by the same reference numerals, and only differences from the scanner shown in FIG. 1 will be briefly described.

[0021] The image reading module 100a includes the illumination device 110 for irradiating light to the document 1 , an image sensor 120a, and imaging optics 130a for forming an image of light reflected from the document 1 on the image sensor 120a and is moved or moves in the second direction S. The image reading module 100a irradiates light onto an object to read image information therefrom, e.g., the document 1 placed on the document tray 200, receives light reflected from the document 1 , and photoelectrically converts the reflected light. [0022] The image sensor 120a may include, for example, a complementary metal-oxide semiconductor (CMOS) sensor array arranged in the first direction M. The length of the image sensor 120a in the first direction M may be equal to or greater than the width of the document 1 having a maximum scanable size. As the imaging optics 130a, a SEFOC lens array (SLA) in which a plurality of micro lenses are arranged in the first direction M is employed. Such components may implement the compact image reading module 100a.

[0023] FIG. 3 is a perspective view of an example of an illumination device employed in the scanners shown in FIGS. 1 and 2. FIG. 4 is a side view of a light guiding member of the example shown in FIG. 3. Referring to FIGS. 3 and 4, the illumination device 110 may include a light guiding member 10 and a light source

20.

[0024] The light guiding member 10 is a photo-transmissive member having a length Lm in the first direction M corresponding to the width of the document 1 and a length Ls in the second direction S. The light guiding member 10 may include a light transmitting unit 10-1 , a light emitting unit 10-2, and a light blocking unit 10-4. The light emitting unit 10-2 is located at one side of the light transmitting unit 10-1 in the second direction S. The light emitting unit 10-2 includes a light emission surface 12 through which light is emitted toward the document 1 and a light scattering pattern 13, which faces the light emission surface 12 and changes the traveling path of light propagated from the light transmitting unit 10-1 to be emitted through the light emission surface 12. The light blocking unit 10-4 is between the light transmitting unit 10-1 and the light emitting unit 10-2, and blocks light irradiated from the light source 20 to prevent the light from being directly incident on the light scattering pattern 13.

[0025] The light source 20 irradiates light into the light guiding member 10 through a side portion of the light guiding member 10 in the first direction M. For example, the light source 2 irradiates light into the light transmitting unit 10-1 through a side portion 11 of the light transmitting unit 10-1 in the first direction M. There may be one or more light sources 20. The light source 20 may include a plurality of light sources 20 for irradiating light of different colors into the light guiding member 10. As described above, the illumination device 110 sequentially irradiates light of R, G, and B colors to the document 1 for color scanning. To this end, the plurality of light sources 20 may include three light sources that emit light of R, G, and B colors, respectively. Each of the three light sources may include two or more light emitters that emit light of the same color. The light emitters may include, for example, light emitting diodes (LED).

[0026] Light incident into the light transmitting unit 10-1 through the side portion 11 of the light transmitting unit 10-1 in the first direction M is propagated in the first direction M and the second direction S by internal reflection, maybe total reflection, and emitted toward the document 1 through the light emission surface 12. The light emission surface 12 may be provided at one end of the light emitting unit 10-2 in the second direction S. In one example, the light emission surface 12 may be implemented by a surface cut obliquely at one end of the light emitting unit 10-2 in the second direction S. The inclination angle of the light emission surface 12 may be appropriately determined, such that light reflected from the document 1 may be received by the image sensor 120 via the imaging optics 130.

[0027] The light scattering pattern 13 is provided in the light emitting unit 10-2. The light scattering pattern 13 is positioned to face the light emission surface 12. The light scattering pattern 13 may include various patterns, e.g., triangles arranged in the first direction M, dots for scattering light, etc. In this example, the light scattering pattern 13 is provided on a bottom surface 17 of the light emitting unit 10-2 facing the light emission surface 12. The traveling path of light propagating in the first direction M and the second direction S inside the light transmitting unit 10-1 and the light emitting unit 10-2 by internal total reflection is changed as the light is scattered by the light scattering pattern 13, and the light is emitted from the light guiding member 10 through the light emission surface 12. [0028] As described above, the illumination device 110 having a structure in which light is incident through the side portion 11 of the light guiding member 10 is referred to as an edge-light type illumination device. In an edge-light type illumination device, light distribution in the first direction M on a document surface needs to be uniform. Also, the directivity of light emitted through the light emission surface 12 needs to be weakened.

[0029] Referring to FIG. 4, a part of light emitted from the light source 20 (indirect light (IDL)) is incident on the light scattering pattern 13 after being reflected, maybe totally reflected, one or more times inside the light transmitting unit 10-1 and the light emitting unit 10-2. A part of the light emitted from the light source 20 (direct light (DL)) may be directly incident on the light scattering pattern 13 without being totally reflected inside the light transmitting unit 10-1 and the light emitting unit 10-2. Since the indirect light IDL is reflected, maybe totally reflected, a number of times, light distribution on a document surface due to the indirect light IDL is uniform in the first direction M. However, since the direct light DL is incident from the light source 20 directly on the light scattering pattern 13, light distribution on a document surface due to the direct light DL may be non-uniform in the first direction M. In other words, the light distribution on the document surface due to the direct light DL is very high at locations close to the light source 20. The phenomenon is referred to as a chip mirroring effect.

[0030] The chip mirroring effect disturbs implementation of a uniform light distribution in the first direction M. The chip mirroring effect may cause image stains or changes of image density in a scanned image. Since the chip mirroring effect sensitively is affected by the position of the light source 20 in the second direction S, light distribution characteristic of each scanner product may vary, may be significantly vary, due to positional deviations of the light source 20 that may occur in a mass production process.

[0031] Also, the chip mirroring effect may cause a sudden change in the illumination characteristics according to a distance between the document 1 and the document tray 200. This illumination characteristic is referred to as a depth of illumination. Although the document 1 to be in close contact with the document tray 200, the document 1 may be partially lifted from the document tray 200 due to a wrinkle of the document 1 , for example. Also, in scanning a book, the center of the book is most lifted from the document tray 200. In general, when the distance between the document 1 and the document tray 200 is changed, a change in the amount of illumination light reaching a document surface may not be avoided. Illumination light by the indirect light IDL has a uniform light-angle distribution. However, illumination light by the direct light DL has a non-uniform light-angle distribution. That is, particular light angle components are densely included in the illumination light by the direct light DL. When illumination light densely includes particular light angle components, changes in the illumination characteristics according to the distance between the document 1 and the document tray 200 (the height of the document 1 ) may also be affected. A light distribution change of a document surface according to a change of the height of the document 1 in a region exposed to the direct light DL exhibits optically different characteristics from those in most regions in which the indirect light IDL is received. That is, the light distribution of the document surface changes, maybe drastically changes, in the region exposed to the direct light DL as the height of the document 1 changes as compared to the region exposed to the indirect light IDL.

[0032] FIG. 5 is a graph simulating the illumination characteristics on a document surface in the first direction M according to a change of a distance between the document 1 and the document tray 200. In FIG. 5, the horizontal axis represents positions in the first direction M, "0" represents the center in the first direction (M), "-150" represents a position closest to the light source 20, and "+150" represents a position farthest from the light source 20. The vertical axis represents relative values of the amount of illumination light. Due to the chip mirroring effect, light with strong directivity is irradiated to a position of a document surface close to the light source 20 in the first direction M. The stronger the directivity is, the sharper the change of illumination characteristics is induced according to the distance between the document 1 and the document tray 200. Therefore, as the document 1 becomes farther away from the document tray 200, the illumination characteristics at positions of a document surface close to the light source 20 in the first direction M may be changed, even drastically, and thus the light distribution on the document surface in the first direction M may become more non-uniform. This may be seen from a portion indicated as "C" in FIG. 5.

[0033] The change, maybe drastic change, in the lighting characteristics due to the chip mirroring effect also depends on the position of the light source 20. Therefore, when the plurality of light sources 20 for irradiating light of R, G, and B colors are employed, positions at which the chip mirroring effects occur vary from one color to another, and thus band-like scan color defects may be formed or color defects may occur at different positions for one color to another in a color scan image. [0034] Therefore, a method of reducing or eliminating the direct light DL may be desired. According to the scanner of this example, the light guiding member 10 employs the light blocking unit 10-4 that is between the light transmitting unit 10-1 and the light emitting unit 10-2 and prevents light irradiated from the light source 20 from being directly incident on the light scattering pattern 13 between the light transmitting unit 10-1 and the light emitting unit 10-2. In other words, the light blocking unit 10-4 partially or entirely blocks the direct light DL. Referring to FIGS. 3 and 4, in an example, the light blocking unit 10-4 may be implemented by a recessed portion 16, which is recessed from a bottom surface 14 of the light transmitting unit 10-1 toward a top surface 15 thereof and forms an air gap between the light transmitting unit 10-1 and the light emitting unit 10-2. As a result, the direct light DL is reflected, maybe totally reflected, at a sidewall 161 forming the boundary between the recessed portion 16 and the light transmitting unit 10-1 and may propagate into the light transmitting unit 10-1 without being incident on the light emitting unit 10-2. The sidewall 161 may be inclined at an acute angle with respect to a thickness direction. The thickness direction is a direction orthogonal to the first direction M and the second direction S.

[0035] A recess amount Ld of the recessed portion 16 may be determined, such that the direct light DL is not directly incident on the light scattering pattern 13 partially or entirely. In an example, the recess amount Ld of the recessed portion 16 may be equal to or greater than at least an half a thickness Lt of the light transmitting unit 10-1. As a result, most of the direct light DL may be blocked to not to be directly incident on light scattering pattern 13.

[0036] The light guiding member 10 may include a connecting unit 10-3 that connects the light transmitting unit 10-1 and the light emitting unit 10-2, such that the indirect light IDL of light irradiated from the light source 20 is incident on the light scattering pattern 13. In the thickness direction, the connecting unit 10-3 is positioned to face the recessed portion 10-4. The indirect light IDL may propagate from the light transmitting unit 10-1 to the light emitting unit 10-2 through the connecting unit 10-3. The connecting unit 10-3 is implemented by an upper portion of the recessed portion 16. A thickness Lc of the connecting unit 10-3 from the top surface 15 of the light transmitting unit 10-1 is smaller than the thickness Lt of the light transmitting unit 10-1. A thickness Lc of the connecting unit 10-3 from the top surface 15 of the light transmitting unit 10-1 may be equal to or less than a half the thickness Lt of the light transmitting unit 10-1.

[0037] Since the transmission path of the direct light DL between the light source 20 and the light scattering pattern 13 is blocked by the light blocking unit 10-4, the chip mirroring effect may be reduced or prevented. That is, since light irradiated from the light source 20 passes through the connecting unit 10-3 and reaches the light scattering pattern 13 after being reflected, maybe totally reflected, at least once inside the light guiding member 10, and thus the chip mirroring effect may be reduced or prevented. Therefore, stable scan image quality may be obtained. Also, the variation of the illumination characteristics caused by the change of the height of the document 1 from the document tray 200 may be reduced, and thus a scanned image of stable quality may be obtained from the document 1 of various states or types.

[0038] The shape of the light emitting unit 10-2 in the thickness direction may be a shape capable of guiding light from the light scattering pattern 13 to the light emission surface 12. The width of the light emitting unit 10-2 in the second direction S may be greater than the width of the light scattering pattern 13. For example, the width of the light emitting unit 10-2 in the second direction S may increase from the light scattering pattern 13 toward the light emission surface 12. The width of the light emission surface 12 in the second direction S may be greater than the width of the light scattering pattern 13. As a result, light utilization efficiency may be improved.

[0039] FIG. 6 is a lateral view of one example of a light guiding member 10a. The light guiding member 10a of this example is different from the light guiding member 10 shown in FIGS. 3 and 4 in that a light diffuser for diffusing light is formed on the light emission surface 12 in the light guiding member 10a of this example. Referring to FIG. 6, the light diffuser may be implemented by, for example, a lenticular lens array 18. The lenticular lens array 18 may include, for example, a plurality of cylindrical lenses arranged in the first direction M. By forming a light diffuser on the light emission surface 12, the directivity of light emitted from the light emission surface 12 may be weakened. As a result, the chip mirroring effect may be reduced to make the light distribution on a document surface more uniform.

[0040] FIG. 7 is a lateral view of one example of a light guiding member 10b. Referring to FIG. 7, in the light guiding member 10b of this example, the bottom surface 17 of the light emitting unit 10-2 having formed thereon the light scattering pattern 13 is substantially parallel to the light emission surface 12, unlike in the light guiding member 10 shown in FIGS. 3 and 4. Therefore, light scattered by the light scattering pattern 13 may be effectively guided to the light emission surface 12.

[0041] FIG. 8 is a lateral view of one example of a light guiding member 10c. Referring to FIG. 8, the light guiding member 10c of this example is different from the light guiding member 10b shown in FIG. 7 that a light diffuser for diffusing light is formed on the light emission surface 12 in the light guiding member 10c. The light diffuser may be implemented by, for example, the lenticular lens array 18. By forming a light diffuser on the light emission surface 12, the directivity of light emitted from the light emission surface 12 may be weakened, thereby reducing the chip mirroring effect and further improving uniformity of light distribution on a document surface.

[0042] FIG. 9 is a lateral view of one example of a light guiding member 10d. The light guiding member 10d of this example is different from light guiding members of the above-described examples in the manner of implementing the light blocking unit 10-4. Hereinafter, differences will be described based on positions.

[0043] Referring to FIG. 9, the light guiding member 10d may include the light transmitting unit 10-1 and the light emitting unit 10-2. The light emitting unit 10-2 is located on one side of the light transmitting unit 10-1 in the second direction S. The light emitting unit 10-2 includes a light emission surface 12 through which light is emitted toward the document 1 and a light scattering pattern 13, which faces the light emission surface 12 and changes the traveling path of light propagated from the light transmitting unit 10-1 to be emitted through the light emission surface 12.

[0044] The light scattering pattern 13 is located below the bottom surface 14 of the light transmitting unit 10-1 in the thickness direction orthogonal to the first direction M and the second direction S. In one example, the light emitting unit 10-2 may include an extended portion 10-5 that extends downwardly from the bottom surface 14 of the light transmitting unit 10-1 , that is, in a direction opposite to the light emission surface 12. The light scattering pattern 13 may be formed on a bottom surface 19 of the extended portion 10-5.

[0045] An extended length Le of the extended portion 10-5 may be determined, such that the direct light DL is not directly incident on the light scattering pattern 13 partially or entirely. For example, the extended length Le of the extended portion 10-5 may be equal to or greater than half the thickness Lt of the light transmitting unit 10-1. As a result, most of the direct light DL may be blocked to not to be directly incident on light scattering pattern 13, and thus the chip mirroring effect may be reduced or prevented. In other words, since light irradiated from the light source 20 reaches the light scattering pattern 13 after being reflected, maybe totally reflected, at least once inside the light guiding member 10d, and thus the chip mirroring effect may be reduced or prevented. Therefore, stable scan image quality may be obtained. Also, the variation of the illumination characteristics caused by the change of the height of the document 1 from the document tray 200 may be reduced, and thus a scanned image of stable quality may be obtained from the document 1 of various states or types. [0046] As indicated by a dotted line in FIG. 9, a light diffuser for diffusing light may be formed on the light emission surface 12. The light diffuser may be implemented by, for example, the lenticular lens array 18. By forming a light diffuser on the light emission surface 12, the directivity of light emitted from the light emission surface 12 may be weakened, thereby reducing the chip mirroring effect and further improving uniformity of light distribution on a document surface.

[0047] The shape of the light emitting unit 10-2 in the thickness direction may be a shape capable of guiding light from the light scattering pattern 13 to the light emission surface 12. FIG. 10 is a lateral view of one example of a light guiding member 10e. Referring to FIG. 10, the width of the light emitting unit 10-2 in the second direction S may be greater than the width of the light scattering pattern 13. For example, the width of the light emitting unit 10-2 in the second direction S may increase from the light scattering pattern 13 toward the light emission surface 12. The width of the light emission surface 12 in the second direction S may be greater than the width of the light scattering pattern 13. As a result, light utilization efficiency may be improved. The lenticular lens array 18 may also be applied to the light guiding member 10e of this example.

[0048] FIG. 11 is a lateral view of one example of a light guiding member 10f. In the light guiding member 10f of this example, the bottom surface 19 of the light emitting unit 10-2 having formed thereon the light scattering pattern 13 is substantially parallel to the light emission surface 12, unlike in the light guiding member 10 shown in FIGS. 9 and 10. Therefore, light scattered by the light scattering pattern 13 may be effectively guided to the light emission surface 12. [0049] It should be understood that examples described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example should typically be considered as available for other similar features or aspects in other examples. While one or more examples have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.