JP2010087809A - Document scanner, and image forming apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently cool a light source of a document scanner. <P>SOLUTION: The invention relates to a document scanner including: an elongated light guide member which includes a light source part at an edge and diffuses illumination light of the light source part in a main scanning direction with respect to a document; and a scan member for moving the light guide member in a sub scanning direction with respect to the document, wherein the light source part includes a semiconductor light-emitting element mounted on a substrate and a heat radiating member in contact with the substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a document reading apparatus and an image forming apparatus using the same.

As a background art of the present invention, an image sensor unit including a light source having an LED at an end of an elongated light guide plate and a light receiving unit having a line-shaped sensor array is mounted on a rail and read in a sub-scanning direction. ) And an image reading apparatus that reads an image of a document is known (for example, see Patent Document 1).
Japanese Patent No. 3885088

By the way, when scanning a document using a combination of a light guide plate and a point light source such as an LED, it is necessary to pass a large current to the light source in order to obtain a sufficient amount of light. The problem of deterioration arises. There is also a method of providing a fan for forced air cooling, but the more strongly the air cooling fan cools, the easier it is for dust to enter from the outside air, and another problem that the image quality deteriorates by adhering to optical parts such as mirrors and lenses Occurs.
Therefore, a method for efficiently cooling such a light source has been demanded.

  According to the present invention, an elongate light guide member that includes a light source unit at an end and diffuses irradiation light of the light source unit with respect to the document in the main scanning direction, and a scanning member that moves the light guide member in the sub scanning direction with respect to the document The document reading device is provided with a light source unit including a semiconductor light emitting element mounted on a substrate and a heat radiating member in contact with the substrate.

  According to this invention, since the light source is composed of the semiconductor light emitting element mounted on the substrate and the heat radiating member in contact with the substrate, the heat generated by the light source is transmitted from the substrate to the heat radiating member, and the light source is efficiently cooled. .

The document reading apparatus according to the present invention is characterized in that a light source unit is provided at the end and an elongated light guide member that diffuses light emitted from the light source unit in the main scanning direction with respect to the document, and the light guide member is sub-scanned with respect to the document. The light source unit includes a semiconductor light emitting element mounted on the substrate and a heat dissipation member that contacts the substrate.
Examples of the semiconductor light emitting device in the present invention include solid state devices such as light emitting diodes and laser diodes.

The heat radiating member is preferably a metal member.
The elongated light guide member may have light source portions at both ends.
The light guide member may include a pair of rod-shaped light guide members arranged in parallel in two rows.
The heat dissipation member may be composed of two members that sandwich the substrate from both sides.
You may further provide a cooling fin and the connection member which thermally connects a thermal radiation member to a cooling fin.
In another aspect, the present invention provides an image forming apparatus including a document reading device.

FIG. 1 is an explanatory view of the configuration of an image forming apparatus according to the present invention.
As shown in FIG. 1, the image forming apparatus 1 includes an image reading device 2. The image reading apparatus 2 is placed on a document placing table 11 made of transparent glass, a double-sided automatic document feeder (RADF) 12 for automatically feeding a document onto the document placing table 11, and the document placing table 11. A document image reading unit for scanning and reading a document image, that is, a scanner unit 13 is provided.

  The RADF 12 is a device that sets a plurality of documents at once on a document tray and automatically feeds the set documents one by one onto the document placement table 11 of the scanner unit 13. The RADF 12 includes a conveyance path for a single-sided document, a conveyance path for a double-sided document, a conveyance path switching unit, and the like so that the scanner unit 13 can read one or both sides of the document according to a user's selection. Has been.

  The scanner unit 13 includes a first scanning unit 14 and a second scanning unit 15 for guiding a reflected light image from a document to a photoelectric conversion element (CCD) 17 and an imaging lens for forming a reflected light image on the CCD 17. 16 is composed.

  In the image reading apparatus 2, the scanner unit 13 is driven on the lower surface of the document placing table 11 while sequentially placing the document to be read on the document placing table 11 by the operation related to the RADF 12 and the scanner unit 13, and the document image Read.

  The image data obtained by reading the document image with the scanner unit 13 is subjected to various processes and then temporarily stored in the image memory. The image data is output from the memory to the image forming unit 3 in accordance with an output instruction. Then, after a visible image is reproduced on the photosensitive drum 22, the image is transferred onto a sheet to form a toner image.

  The image forming unit 3 includes a laser writing unit (LSU) 21 and an electrophotographic process unit 20 for forming an image. The laser writing unit 21 is a semiconductor laser that emits laser light according to image data read from the image memory or image data transferred from an external device such as a personal computer, a polygon mirror that deflects the laser light at a constant angular velocity, and a constant angular velocity. It has an f-θ lens that corrects the deflected laser light so that it scans the photosensitive drum 22 of the electrophotographic process unit 20 at a constant speed. The electrophotographic process unit 20 has a charging device 23, a developing device 24, a transfer device 25, and a cleaning device 27 arranged around the photosensitive drum 22 in accordance with a well-known mode, and a fixing device 28 is further arranged downstream of the photosensitive drum 22. Arranged and configured.

  The paper feed unit 4 includes first to third cassettes 31 to 33 and a manual feed tray 35. The sheet feeding / conveying unit 38 includes a sheet feeding roller, a conveying roller, and a registration roller for conveying a sheet from the sheet feeding unit 4 to a transfer position between the photosensitive drum 22 and the transfer device 25.

In the three trays in the first to third cassettes 31 to 33 in the sheet feeding unit 4, sheets are stacked and stored for each size, and a cassette that stores sheets of a size desired by the user or When a tray is selected, the sheets are fed one by one from the top of the sheet bundle in the tray, and sequentially conveyed toward the electrophotographic process unit 20 via the conveyance path of the sheet feeding conveyance unit 38.
A paper discharge path 29 is provided downstream of the fixing device 28 in the paper conveyance direction.

  In the electrophotographic process unit 20, the image data read from the image memory is formed as an electrostatic latent image on the surface of the photosensitive drum 22 by scanning the laser beam with the laser writing unit 21. The toner image visualized by the toner is electrostatically transferred by the transfer device 25 onto the surface of the paper conveyed from the paper supply unit 4 and fixed by the fixing device 28.

The sheet on which the image is formed on one side in this way is sent from the fixing device 28 to the stacking tray 63 via the conveyance roller 61 and the switching gate 9.
On the other hand, when double-sided image formation (double-sided printing) is specified, the sheet printed on one side is discharged toward the stacking tray 63 by the reversing roller 62, but the sheet is not completely discharged, but the end of the sheet. The reversing roller 62 is rotated in the reverse direction. Then, the paper is reversely conveyed in the reverse direction, that is, in the direction of the refeed conveyance unit 42.
At this time, the switching gate 9 is switched from upward to downward. The reversely conveyed sheet passes through the refeed conveyance unit 42 and is supplied again to the image forming apparatus 3 to perform duplex printing.

  FIG. 2 is a perspective view showing the scanner unit 13. As shown in FIG. 2, a flat bottom plate 135 b is attached to the bottom of a frame 135 that is an outer frame of the scanner unit 13. The imaging lens 16 and the CCD 17 shown in FIG. 1 are built in the portion covered with the dark box 119 on the bottom plate 135b. For the frame 135 and the bottom plate 135b, for example, a steel plate whose surface is galvanized is used. The first scanning unit 14 and the second scanning unit 15 are attached so as to move over the dark box 119.

  The first scanning unit 14 includes a metal frame 161 that has wire fixing portions 121a and 121b (see FIG. 10) at both ends and on which the illumination unit 162 is mounted. A drive wire 145a is fixed to the wire fixing portion 121a, and a drive wire 145b is fixed to the wire fixing portion 121b. Further, both end portions of the first scanning unit 14 are slidably supported by the guide rails 136a and 136b, respectively.

  The second scanning unit 15 includes wire frames 122 a and 122 b at both ends, and includes a metal frame 122 that supports the mirror 117 and the mirror 118. A pulley 149a is attached to the wire fixing portion 122a, and a drive wire 145a is hung on the pulley 149a. A pulley 149b is attached to the wire fixing portion 122b, and a drive wire 145b is hung on the pulley 149b. Further, both end portions of the second scanning unit 15 are slidably supported by the guide rails 137a and 137b, respectively.

  The drive motor 138 is a stepping motor that drives the first scanning unit 14 and the second scanning unit 15, and its rotation is controlled by a motor control circuit (not shown). The rotation of the output shaft of the drive motor 138 is transmitted to the drive shaft 143 via the timing belt 144 and rotates the drive pulleys 139a and 139b attached to both ends of the drive shaft 143. Driving wires 145a and 145b are wound around the driving pulleys 139a and 139b, respectively, and the driving wires 145a and 145b are fixed to the first scanning unit 14 and the second scanning unit 15, respectively. The rotation of the drive pulleys 139a and 139b is converted into linear motion by the drive wires 145a and 145b, and the first scanning unit 14 and the second scanning unit 15 are moved in the sub-scanning direction (arrow A direction). The drive shaft 143 and the drive pulleys 139a and 139b are made of steel, and steel wires are used for the drive wires 145a and 145b.

3A and 3B are explanatory views schematically showing the configuration and operation of the scanner unit according to the present invention.
As shown in FIG. 3A, as described above, the scanner unit 13 includes the illumination unit 162 that illuminates the document placed on the document placement table 11, the CCD 17 that receives light from the document, and the light from the document. An imaging optical system that forms an image on the CCD 17 is provided. The document table 11 is made of transparent glass and is formed in a rectangular plate shape. An original is placed on the upper surface of the original placing table 11.

  The imaging optical system includes an imaging lens 16 and a mirror group that guides light from the document to the imaging lens 16. The mirror group includes mirrors 116, 117, and 118. The light emitted from the illumination unit 162 is reflected by the surface of the document placed on the document placement table 11. The light reflected downward from the surface of the document is reflected by the mirror 116, and then sequentially reflected by the mirror 117 and the mirror 118 and guided to the imaging lens 16. The mirror 116 is mounted on the metal frame 161 of the first scanning unit 14 together with the illumination unit 162. The mirrors 117 and 118 are mounted on the metal frame 122 of the second scanning unit 15.

  The first scanning unit 14 is driven by the drive system shown in FIG. 2, and moves at a constant speed V in the direction of the arrow A1 (reading direction) from the scanning start end P1 as shown in FIG. The second scanning unit 15 is driven by the drive system and moves in the direction of the arrow A1 at a speed (V / 2) that is a half of the speed V of the first scanning unit 14. As the first scanning unit 14 and the second scanning unit 15 move, the position (reading position) of the original image formed on the CCD 17 moves from the scanning start end P1 to the scanning end P2, as shown in FIG. While the first scanning unit 14 and the second scanning unit 15 are moving, the speed ratio between them is maintained at 2: 1, so that the optical path length from the document surface to the imaging lens 16 is kept constant. As a result, an image of the document on the document table 11 is formed on the CCD 17 at each reading position from the scanning start end P1 to the scanning end P2.

  FIG. 4 is a block diagram illustrating a configuration of the image reading apparatus 2, and the document reading apparatus 2 includes a scanner unit 13, an image processing unit 5, a storage unit 6, and a communication unit 8. As described above, the scanner unit 13 irradiates the original with light, guides the light reflected from the original to the imaging optical system, and reads it by the CCD 17. The image signal of the document read by the CCD 17 is output to the image processing unit 5. The image processing unit 5 performs A / D conversion on the image signal from the CCD 17 to convert it into image data, performs image processing such as color conversion processing and filter processing on the converted image data, and executes shading correction. A storage unit (memory) 6 temporarily stores image data to be processed when the image processing unit 5 performs image processing on the image data. Further, the storage unit 6 holds the processed image data until it is transferred to the image forming unit 3 or is transferred to an external device via the communication unit 8. The communication unit 8 receives the image data from the storage unit 6 via the image processing unit 5 and transfers it to an external device.

  The image processing unit 5 and the communication unit 8 include, for example, a CPU, a ROM that stores a program to be executed by the CPU, a RAM that provides a working storage area, a nonvolatile memory that stores setting values of each block that performs image processing, It can be configured by a circuit using an LSI or the like in which circuit blocks for image processing and communication are integrated. The storage unit 6 can be composed of a DRAM or other type of memory element. In addition, a storage device such as an HDD can be applied to the storage unit 6. Further, the CPU also functions as a control unit of the scanner unit 13 and controls its operation.

FIG. 5 is a perspective view showing the illumination unit 162.
As shown in FIG. 5, the illumination unit 162 is emitted from the light source units 71 and 72 extending between the light source units 71 and 72 provided at both ends so as to be opposed to each other and the opposed light source units 71 and 72. The first light guide plate 73 and the second light guide plate 74 are parallel to each other and diffused in the main scanning direction (arrow X direction). The first and second light guide plates 73 and 74 are, for example, square bars having a cross-sectional dimension of 8 mm × 9 mm and a length of 330 mm, and an acrylic resin is used as the material thereof.

  Hereinafter, although the light source parts 71 and 72 are demonstrated, since the light source parts 71 and 72 have the mutually same structure, only the light source part 71 is demonstrated.

  As shown in FIG. 6, the light source unit 71 includes a substrate 77, and a first heat radiating member 78 and a second heat radiating member 79 that sandwich the substrate 77 and make contact with both surfaces of the substrate 77.

  The first and second heat radiating members 78 and 79 are both made of aluminum having excellent heat dissipation and thermal conductivity.

  The board 11 is an aluminum printed wiring board or an epoxy resin printed wiring board, and FIG. 11 is a connection diagram of an electric circuit mounted on the board 77. As shown in FIG. 11, first and second light emitting diodes 75 and 76, a transistor 87, a resistor r, and a comparator 86 are mounted on the substrate 77. In operation, a DC voltage is applied to the series circuit of the first and second light emitting diodes 75 and 76, the transistor 87, and the resistor r from the outside. When the current i flows through the series circuit, feedback control is performed by the comparator 86 and the transistor 87 so that the reference voltage Vref = ir, and the current i is held constant.

7 to 9 are assembly explanatory views for showing the configuration of the light source unit 71 in more detail.
As shown in FIG. 7, the first heat radiating member 78 is plate-shaped and includes through holes 80a and 80b and fixing bolts 81a and 81b inserted into the through holes 80a and 80b.

  As shown in FIG. 8, the substrate 77 has through holes 82 a and 82 b and has the first light emitting diode 75 and the second light emitting diode 76 mounted thereon. The substrate 77 is installed such that the back surface is in contact with the first heat radiating member 78, and fixing bolts 81a and 81b are inserted into the through holes 82a and 82b.

  As shown in FIG. 9, the second heat radiating member 79 has a block shape and has screw holes 83 a and 83 b and concave portions 79 a and 79 b that receive the tips of the first and second light guide plates 73 and 74. The second heat dissipating member 79 is disposed so as to contact the surface of the substrate 77 and the first and second light emitting diodes 75 and 76 can be seen through the recesses 79a and 79b, and the fixing bolts 81a and 81b are screw holes 83a. , 33b. As a result, the substrate 77 is firmly tightened from both sides while being sandwiched between the first and second heat radiating members 78 and 79.

  As shown in FIG. 6, both ends of the first and second light guide plates 73 and 74 are fitted in the recesses 79a and 79b of the light source parts 71 and 72 assembled in this way, and the illumination part 162 is shown in FIG. In this manner, the metal frame 161 is fixed.

  In the illumination unit 162, the end surfaces of the first and second light guide plates 73 and 74 are mounted on the substrate 77 by positioning the ends of the first and second light guide plates 73 and 74 by the recesses 79a and 79b. The first and second light emitting diodes 75 and 76 are opposed to each other. Thereby, the light emitted from the first and second light emitting diodes 75 and 76 is guided and diffused in the main scanning direction along the first and second light guide plates 73 and 74, respectively.

  As described with reference to FIG. 2, both ends of the metal frame 161 that supports the illumination unit 162 shown in FIG. 10 are slidably supported by the guide rails 136a and 136b. At both ends of the metal frame 161, contact members 171a and 171b that contact the guide rails 136a and 136b are provided. The contact members 171a and 171b are made of ABS resin so as to have wear resistance and slipperiness.

  Therefore, in each of the light source units 71 and 72, heat generated from the first and second light emitting diodes 75 and 76 is transmitted to the first and second heat radiating members 78 and 79 via the substrate 77 and is diffused into the atmosphere. In addition, a part thereof is transmitted to the guide rails 136a and 136b and the frame 135 via the metal frame 161 and the contact members 171a and 171b, or is transmitted to the frame 135 via the drive wires 145a and 145b. It is emitted into the atmosphere.

FIG. 12 is a diagram corresponding to FIG. 10 showing a modification of the above-described embodiment.
In this modification, the metal frame 161 includes cooling fins 170a and 170b in the vicinity of the light source portions 71 and 72 as shown in FIG. Therefore, the heat generated from the first and second light emitting diodes 75 and 76 is transmitted to the cooling fins 170a and 170b through the substrate 77, the first and second heat radiating members 78 and 79, and the metal frame 161, and into the atmosphere. Be exhaled. That is, the heat radiation action of the first and second light emitting diodes 75 and 76 is further improved, and the temperature rise is efficiently suppressed. In this case, the metal frame 161 acts as a connecting member that thermally connects the first and second heat radiating members 78 and 76 and the cooling fins 170a and 170b.

1 is a configuration explanatory diagram of an image forming apparatus according to the present invention. FIG. It is a perspective view of the scanner unit concerning this invention. It is explanatory drawing of a structure and operation | movement of the scanner unit shown in FIG. 1 is a block diagram showing a configuration of an image reading apparatus according to the present invention. It is a perspective view which shows the illumination part which concerns on this invention. It is a principal part enlarged view of FIG. It is a principal part perspective view of FIG. It is a principal part perspective view of FIG. It is a principal part perspective view of FIG. It is principal part sectional drawing of FIG. It is an electric circuit diagram of the components mounted on the substrate according to the present invention. FIG. 11 is a view corresponding to FIG. 10 showing a modification of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image reading apparatus 3 Image forming part 4 Paper feed part 5 Image processing part 6 Storage part 8 Communication part 9 Switching gate 11 Document placing stand 12 Automatic document feeder (RADF) corresponding to both sides
13 Scanner unit 14 First scanning unit 15 Second scanning unit 16 Imaging lens 17 CCD

20 Electrophotographic process section 21 Laser writing unit 22 Photoconductor drum 23 Charging device 24 Developing device 25 Transfer device 27 Cleaning device 28 Fixing device 29 Paper discharge path 31 First cassette 32 Second cassette 33 Third cassette 35 Manual feed tray 38 Paper feed Transport unit 42 Refeed transport unit

61 Conveying roller 62 Reverse roller 63 Stacking tray 71, 72 Light source 73 First light guide plate 74 Second light guide plate 75 First light emitting diode 76 Second light emitting diode 77 Substrate 78 First heat radiating member 79 Second heat radiating members 79a, 79b Recess

80a, 80b Through hole 81a, 81b Fixing bolt 82a, 82b Through hole 83a, 83b Screw hole 86 Comparator 87 Transistor 83a, 83b Screw hole 116 Mirror 117 Mirror 118 Mirror 119 Dark box 121a Wire fixing part 121b Wire fixing part 122 Metal frame 122a Wire fixing part 122b Wire fixing part

135 Frame 135b Bottom plate 136a Guide rail 136b Guide rail 137a Guide rail 137b Guide rail 138 Drive motor 139a Drive pulley 139b Drive pulley 143 Drive shaft 144 Timing belt 145a Drive wire 145b Drive wire 149a Pulley 149b Pulley 161 Metal frame 162 Illuminator 170a Cooling fin 170b Cooling fin

Claims (10)

  A light source comprising a light source at the end and diffusing light emitted from the light source in the main scanning direction with respect to the document, and a scanning member for moving the light guide in the sub-scanning direction with respect to the document. A document reading apparatus, wherein the section includes a semiconductor light emitting element mounted on a substrate and a heat radiating member in contact with the substrate.   2. The document reading apparatus according to claim 1, wherein the semiconductor light emitting element is a light emitting diode.   2. The document reading apparatus according to claim 1, wherein the heat dissipating member is a metal member.   2. The document reading apparatus according to claim 1, wherein the elongated light guide member has light source portions at both ends.   2. The document reading apparatus according to claim 1, wherein the light guide member comprises a pair of bar-shaped light guide members arranged in parallel in two rows.   2. The document reading apparatus according to claim 1, wherein the heat dissipating member comprises two members sandwiching the substrate from both sides.   The document reading apparatus according to claim 1, further comprising a cooling fin and a connection member that thermally connects the heat radiating member to the cooling fin.   The document reading apparatus according to claim 1, further comprising guide rails that support both ends of the scanning member.   The document reading apparatus according to claim 1, further comprising a drive wire for driving the scanning member.   An image forming apparatus comprising the document reading device according to claim 1.

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