Two-Dimensional Image Pick-up Device (TECHNICAL FIELD) 5 The present invention relates to a two-dimensional image pick-up device in which subscanning is mechanically carried out by using a one-dimensional image pick-up element. (BACKGROUND ART)

10 Figure 7 is a perspective view illustrating a conventional two-dimensional image pick-up device disclosed in the Japanese Laid-Open Patent Publication (unexamined) No. 58-69173, Figure 8 is an exploded perspective view illustrating an element moving carriage

15 and guide rail of the conventional two-dimensional image pick-up device, and Figure 9 is a sectional view illustrating that the element moving carriage and the guide rail in Figure 8 are in an assembled state.

In these drawings, reference numeral 1 indicates a

20 frame of the two-dimensional image pick-up device, numeral 2 indicates the guide rail mounted on the frame 1, and numeral 3 indicates the element moving carriage which is supported on the guide rail 2 through the bearings 4, 5 (see Figures 8 and 9) so as to be movable

25 in the direction of the arrows A and B. The one- dimensional image pick-up element (not illustrated) is attached to the element moving carriage 3. Numeral 6 indicates an arm of the element moving carriage 3, numeral 7 indicates a spring for downward partial loading

30 connected to the arm 6, numeral 8 indicates a micrometer head which is disposed beneath the arm 6 and securely fitted to the frame 1 through a fitting member 9. The micrometer head 8 having a spindle 10 connected to the arm 6 comprises a motion converting mechanism 11 of 35 micrometer type which converts an inputted rotary motion to a linear motion in the axial direction of the spindle 10, and a rotary encoder 12 which detects the rotary

motion and generates a pulse for each rotary motion of a specified angle, so that the spindle 10 pushes up the arm 6 of the element moving carriage 3 against the spring 7. Numeral 13 indicates an input gear mounted on the rotary input shaft of the micrometer head 8, numeral 14 indicates an electric motor installed in the vicinity of the micrometer head 8, and numeral 15 indicates an output gear engaged with the input gear 13. Numeral 16 indicates an upper side limit switch disposed above the .element moving carriage 3, and numeral 17 indicates a lower side limit switch disposed beneath the element moving carriage 3. These upper and lower side limit switches 16 and 17 automatically stop the motor 14 when the element moving carriage 3 moving up and down (in linear motion) reaches a prescribed position and turn the switches on. Numeral 18 indicates an optical system which generates image of an original picture on the focal plane, and numeral 19 indicates a disc carriage for exchanging filters. A red filter 20, a green filter 21, a blue filter 22 and a black-and-white filter 23 are respectively arranged in the filter exchanging carriage 19 with equal distance therebetween. Numeral 24 indicates a filter exchanging electric motor which intermittently drives the filter exchanging carriage 19 rotationally, so that each of red, green, blue and black-and-white filers 20 to 23 is exchanged and comes at the position corresponding to the optical system 18. The conventional device of above construction performs following function. When starting the motor 14, the rotary input shaft of the motion converting mechanism 11 is rotationally driven through the output gear 15 and the input gear 13, and the rotation is converted to a linear motion by the motion converting mechanism 11 and transmitted to the micrometer head 8, whereby the the arm 6 of the element moving carriage 3 starts a linear motion so that the one-dimensional image pick-up element of the element

moving carriage 3 is scanned along the guide rail 2. The range of the linear motion of the element moving carriage 3 at the time of scanning is determined by counting pulses from the rotary encoder 12. Further, as the result of intermittent rotational drive of the filter exchanging carriage 19 by means of the filter exchanging motor 24, any one of the red, green, blue and black-and- white filters is exchanged to come at the position corresponding to the optical system 18. Since the conventional two-dimensional image pick-up device is constructed as described above, the element moving carriage 3 and the filter exchanging carriage 19 are individually driven by the two motors 14 and 24 for their exclusive use. Moreover, the rotation of the motor 14 is once converted to a linear motion and transmitted to the element moving carriage 3, and the micrometer head 8 is required for the subscanning of the element moving carriage 3. Accordingly, a problem exists in that the conventional device is undesirably large- sized as a whole. Besides, since the filter exchanging carriage 19 is of rotary type, size of the color filters is required to correspond to the subscanning distance of the one-dimensional image pick-up element 25 at the time of exchanging the filters, whereby the color filters are also obliged to be large-sized. After all, the filter exchanging carriage 19 itself is also large-sized. This brings about such a drawback as increase in cost. (DISCLOSURE OF THE INVENTION)

The present invention was made to overcome the above-discussed drawback and has an object of providing a novel two-dimensional image pick-up device which is small-sized thereby contributing to reduction in cost. To accomplish the foregoing object, in the two- dimensional image pick-up device according to the invention, voice coil type linear motors for driving the element moving carriage in the subscanning direction of. one-dimensional image pick-up element are disposed on

both sides of the element moving carriage on which the one-dimensional image pick-up element is mounted positionally corresponding to the optical system.

In the two-dimensional image pick-up device of the above construction according to the invention, when supplying power to the voice coils of the linear motors, a driving force for moving the element moving carriage is generated in the voice coils, and the one-dimensional image pick-up element is subscanned by the movement of the element moving carriage.

(BRIEF DESCRIPTION OF THE DRAWINGS)

Figure 1 is a partially sectional perspective view of the two-dimensional image pick-up device according to one embodiment of the present invention; Figure 2 is a schematic front view of the two- dimensional image pick-up device;

Figure 3 is a perspective view illustrating relative position detecting means for the element moving carriage and the filter exchanging carriage; Figure 4 is a schematic view illustrating the absolute position detecting means for the element moving carriage;

Figure 5 is a block diagram schematically illustrating the arrangement in Figure 1; Figures 6 and 10 are perspective views illustrating further embodiments;

Figure 7 is a perspective view illustrating the conventional two-dimensional image p ^' ick-up device;

Figure 8 is an exploded perspective view of the element moving carriage and the guide rail of the conventional two-dimensional image pick-up device; and

Figure 9 is a sectional view illustrating that the carriage and the guide rail in Figure 8 are in the assembled state. (BEST MODE FOR CARRYING OUT THE INVENTION)

An embodiment of the present invention is now described with reference to the accompanying drawings, in

which Figure 1 is a partially sectional perspective view of the two-dimensional image pick-up device according to one embodiment of the present invention; Figure 2 is a schematic front view of the two-dimensional image pick-up device; Figure 3 is a perspective view illustrating the relative position detecting means for the element moving carriage and the filter exchanging carriage; Figure 4 is a schematic view illustrating the absolute position detecting means for the element moving carriage; Figure _, 5 is a block diagram schematically illustrating the arrangement in Figure 1 ; and in which like reference numerals are designated to the same or like parts as Figures 7 to 9 to omit repeated description.

In the drawings, numerals 2a, 2b indicate guide rails comprising a pair of round bars disposed at positions parallel to each other, and the element moving carriage 3 is movably supported on the guide rails 2a, 2b through the bearings 4a, 4b (see Figures 1 and 2). Numeral 19 indicates a plate-like filter exchanging carriage which is disposed between the element moving carriage 3 and the optical system 18 (see Figure 5) and driven in the same direction as the element moving carriage 3 in parallel thereto. The filter exchanging carriage 19 is mounted with red filter 20, green filter 21, blue filter 22 and black-and-white filter 23, each arranged at a certain distance therebetween in the direction of width of the filter exchanging carriage 19. Numeral 25 indicates one-dimensional image pick-up element mounted on the element moving carriage 3 to be subscanned, and numeral 26 indicates relative position detecting means mounted on the element moving carriage together with the one-dimensional image pick-up element 25 for detecting a relative position between the element moving carriage 3 and the filter exchanging carriage 19. Numeral 26a indicates a detecting fin of the relative position detecting means 26, and which is attached to the filter exchanging carriage 19. Numeral 27 indicates

voice coils fixed to both ends of the element moving carriage 3, numeral 28 indicates yokes of magnetic circuits each forming a drive source of the element moving carriage 3, and which are arranged on both ends of the element moving carriage 3, and numeral 29 indicates permanent magnets respectively fixed to the yokes 28. The permanent magnets 29 and the voice coils 27 form linear motors Ml which drive the element moving carriage 3 in the subscanning direction of the one-dimensional image pick-up element 25. Numeral 30 indicates rail supporting members respectively provided on the yokes 28, and numeral 31 indicates guide rails each comprising a round bar supported by the rail supporting member 30. Both end portions of the filter exchanging carriage 19 are movably supported by the guide rails 31. Numeral 34 indicates a voice coil which is wounded round the yoke 28 of one of the magnetic circuits serving as a drive source of the element moving carriage 3 and crosses over the magnetic field of the permanent magnet 29, thus forming a part of the linear motor Ml to drive the filter exchanging carriage 19. Numeral 35 indicates an optical senso • serving as the absolute position detecting means for detecting the absolute position of the element moving carriage 3 with respect to the stationary side. The optical sensor 35 is provided with a light source 36 such as light emitting diode attached to the element moving carriage 3 side, a diaphragm plate 37 arranged in front of the light source 36 and having an aperture for restricting irradiation of light from the light source 36, a reflecting mirror 38 and a lens 39 both arranged in front of the light source 36, as illustrated in Figures 4 and 5. Numeral 40 indicates a position detecting circuit for detecting the absolute position of the element moving carriage 3, and numeral 41 indicates a controller to which an absolute position detecting signal and a command signal b from the position detecting circuit 40 are inputted, and from which a control current obtained as

the result of comparison of the signals is sent to the voice coils 21 of. the element moving carriage 3. Numeral 42 indicates a controller to which an input signal and a command signal a from the relative position detecting means 26 are inputted and compared, and from which a control current corresponding to the value obtained by the comparison is supplied to the voice coil 34- of the filter exchanging carriage 19.

The device of the above arrangement performs .following function.

When the current is supplied from the controller 41 to the voice coils 27 of the element moving carriage 3 located in the magnetic field of the permanent magnets 29, a driving force for driving the element moving carriage 3 is generated in the voice coils 27 in the direction of the arrow A (or arrow B) in Figure 1, and, by this driving force, the element moving carriage 3 moves in the driection A (or B) and subscans the one- dimensional image pick-up element 25. When the irradiation of light from the light source 36 is detected by the optical sensor 35 through the diaphragm plate 37, reflecting mirror 38 and lens 39 at the time of subscanning, the detected signal is inputted to the position detecting circuit 40 which detects the absolute position of the element moving carriage 3, and this detected signal is then inputted to the controller 41, whereby the controller 41 compares the input signal from the position detecting circuit 40 with the command signal b and determines a quantity of current to be supplied to the voice coils 27 so that the current corresponding to the determined quantity is supplied thereto. In this manner, the element moving carriage 3 moves in the subscanning direction by a distance which corresponds to the quantity of current determined based on the command signal b, thus positioning the one-dimensional image pick-up element 25 in the subscanning direction.

In the filter exchanging carriage 19, when a

current is supplied from the controller 41 (see Figure 4) to the voice coil 34 for exchanging the color filters located in the magnetic field of the magnetic circuits 28, a force generated in the voice coil 34 serves as a driving force for the filter exchanging carriage 19, whereby the carriage 19 moves in the subscanning direction to exchange each color filter 20 to 23. In this manner, the magnetic circuits 28 perform a function of driving both element moving carriage 3 and filter .exchanging carriage 19. In addition, likewise in the filter exchanging carriage 19, the controller 42 compares the input signal from the relative position detecting means 26 with the command signal a and determines a quantity of current to be supplied to the voice coil 34, so that a relative positional relation between the filter exchanging carriage 19 and the element moving carriage 3 is controlled by the command signal a which corresponds to the determined quantity of current, eventually exchanging the color filters 20 to 23. When the element moving carriage 3 is scanned in accordance with the command signal b, a current is supplied to the voice coil 34 so as to keep a relative positional relation controlled by the command signal a, whereby the element moving carriage 3 and the filter exchanging carriage 19 are held at their appropriate relative position.

In effect, the absolute position of the element moving carriage 3 is detected by the optical sensor 35 without contact, and a relative position between the element moving carriage 3 and the filter exchanging carriage 19 is detected by the relative position detecting means 26, whereby the filter exchanging carriage 19 is controlled by the controller 42 in the system, making it possible to carry out accurately the positioning of the element moving carriage 3 and the subscanning.

Figure 6 illustrates another embodiment of the invention, in which the voice coil 34 for color filter

exchange is so arranged as to cross over the magnetic field of the element driving magnetic circuit 28 on the opposite side of that in Figure 1, and other arrangement and function remain the same as the foregoing embodiment. In addition, the voice coil 34 for color filter exchange can be wound round each yoke of the magnetic circuits 28 on both sides, in which case the filter exchanging carriage 19 is driven on both sides allowing the same to be driven more smoothly. Figure 10 illustrates a further embodiment, in which another linear motor M3 for exclusive use in color filter exchange is additionally disposed on the opposite side of the linear motor M2 for exclusive use in color filter exchange in the foregoing embodiment, so that the filter exchanging carriage 19 is driven by these two linear motors M2 , M3 both for exclusive use in color filter exchange. Accordingly, the driving of the filter exchanging carriage 19 can be carried out furthermore smoothly. The additional linear motor M3 comprises a permanent magnet 33a provided in the yoke 32a of the magnetic circuit of the system, and a voice coil 34a which is attached to the arm 19b on the opposite side of the arm 19a of the filter exchanging carriage 19 in such a manner as to cross the permanent magnet 33, eventually resulting in the same design as the linear motor M2 on the opposite side.

It is also preferred that a PSD (position sensing device) is adopted in place of the optical sensor 35 in the foregoing embodiment. As has been described so far, since voice coil type linear motors are adopted as drive source for subscanning the one-dimensional image pick-up element in the present invention, an advantage is achieved such that the entire device can be small-sized resulting in reduction of cost. (POSSIBILITY OF INDUSTRIAL UTILIZATION)

The present invention can be utilized as an image reader being one of peripheral equipments for computer.