JP2006197016A - Image reader and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means of radiating heat of a CCD image sensor, using simple constitution for a digital image reader which converts optical information on an image obtained by scanning a document into an electrical signal, using a CCD image sensor. <P>SOLUTION: A heat conductor 26 is merely brought into contact with the outer side of the case of the CCD image sensor 20 without being fixed. Here, a portion of the heat conductor 26 is fixed to a case 22 of the image reader, and heat can be radiated via the case 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that reads an image with a CCD (charge coupled device) image sensor, and an image forming apparatus such as a copying machine, a printer, and a facsimile including the image reading apparatus.

  In an image reading apparatus mounted on a digital copying machine or facsimile, an original is irradiated with light from a light source, and the reflected light is guided to a CCD image sensor and converted into an electrical signal to read an image.

  In recent years, CCD drive frequency has been increased and sensitivity has been improved for the purpose of improving reading speed. As a result, heat generation of the CCD image sensor has become a problem.

  As a means for solving such heat generation, (a) as an oscillation source for supplying a clock to the CCD drive pulse generation circuit in order to suppress the heat generation amount of the CCD and peripheral circuits during reading standby and to stabilize the temperature of the CCD, A first oscillator that generates a clock having a frequency necessary for the read operation and a second oscillator that generates a clock having a frequency lower than the frequency are provided. During the read operation period, the oscillation clock of the first oscillator is The signal is supplied to the CCD drive pulse generation circuit through the switching circuit, and the CCD 1 is driven at a high speed. In the read standby period, the oscillation clock of the second oscillator is supplied to the CCD drive pulse generation circuit through the switching circuit, There is a technique for driving the CCD 1 (see, for example, Patent Document 1).

  However, this technique complicates the circuit configuration for switching the drive pulse of the CCD, and requires time for switching. Further, the temperature changes every time the drive pulse is changed, which may affect the read data.

  As another solution, (b) in order to reduce the heat generated in the CCD and the CCD driver circuit in the image reading apparatus in which the CCD and the CCD driver circuit are in close contact with each other, A MOS transistor is inserted as a switch between the power outputs of the power supply unit that supplies power to them, and the CPU turns off the MOS transistor to control power supply when waiting for CCD reading to suppress temperature rise of the CCD and CCD driver circuit There is a technique (see, for example, Patent Document 2).

  However, this method also requires power supply switching means, which complicates the circuit configuration, and this method cannot cope with the temperature rise during continuous reading.

  Further, as a heat countermeasure for the CCD, the heat sink is pressed from both sides of the CCD and the PCB substrate, and the other end of the heat sink is positioned in the space, or the extension part of the heat sink and the components of the image reading device There is a technique in which a flexible heat conducting member is interposed in order to prevent stress on the CCD (for example, see Patent Document 3).

  However, in this technique, the heat dissipation effect is not sufficient in the example in which the other end side of the heat sink is positioned in the space, and in the example in which the heat conducting member (thin copper plate) is provided in the extending portion of the heat sink. Becomes complicated.

Japanese Patent Laid-Open No. 6-268821 JP-A-6-141132 JP-A-10-210221

  An object of the present invention is to provide an image reading apparatus and an image forming apparatus provided with means for radiating heat generated by a CCD image sensor with a simple configuration.

The present invention has the following configuration in order to achieve the above object.
In an image reading apparatus according to the present invention, in a digital image reading apparatus that converts optical information of an image obtained by scanning a document into an electrical signal using a CCD image sensor, the image reading apparatus is disposed outside the casing of the CCD image sensor. The heat conductor was brought into contact (claim 1). Here, a part of the heat conductor is preferably fixed to the case of the image reading apparatus. In addition, it is preferable that the thermal conductor has an elastic portion at a contact portion with the outside of the casing of the CCD image sensor. A leaf spring can be used as the elastic body (claim 4). Alternatively, a compression spring can be used as the elastic body (claim 5). An image reading apparatus to which these inventions are applied can be mounted on an image forming apparatus.

  In the present invention, the heat generated from the CCD can be efficiently transmitted to the heat conductor and dissipated by a simple configuration in which the heat conductor is brought into contact with the outside of the CCD image sensor casing.

  Embodiments of the present invention will be described below.

[1] Embodiment 1
FIG. 1 shows an overall layout of a member configuration of an image reading apparatus to which the present invention is applied. In FIG. 1, various members constituting the image reading device 23 are configured in a casing-like case 22. A contact glass 10 is provided on the upper portion of the case 22. A white reference plate 7 is held by a glass retainer 8 at the left end of the contact glass 10. Further, a narrow sheet-through contact glass 9 is fitted into a part of the glass presser 8. This contact glass 9 is provided as an optical path for the reflected light of the original during automatic original feeding.

  The first mirror 2 is located inside the case 22 and directly below the contact glass 9. A lamp 1 for illuminating the document is located above the first mirror 2. The first mirror 2 and the lamp 1 are mounted on the first carriage 3. A second carriage 6 is located on the left side of the first carriage 3. A second mirror 4 and a third mirror 5 are mounted on the second carriage 6.

  Reflected light (image information) from the document irradiated by the lamp 1 is folded back in the order of the first mirror 2, the second mirror 4, and the third mirror 5 and follows the optical path a and is positioned near the right end in the case through the lens 19. The image is formed on the CCD image sensor 20. The CCD image sensor 20 is integrally formed with a CCD substrate 21. The CCD substrate 21 is held in a case by means not shown. In addition, the heat conductor 23 is in contact with the outside of the casing constituting the exterior portion of the CCD image sensor 20. The other end of the heat conductor 23 is fixed to the case 22.

  The illustrated positions of the first carriage 3 and the second carriage 6 are home positions. When a book document is placed on the contact glass 10, the first carriage 3 and the second carriage 6 reciprocate from these home positions to scan the document. When an automatic document feeder is mounted on the image reading device 23, the document is moved by the automatic document feeder, so that the first carriage 3 and the second carriage 6 are fixed at their home positions. The document is read by the CCD image sensor as it is.

  The reciprocating motion of the first carriage 3 and the second carriage 6 during scanning is performed along with the movement of the drive wire 14 hung between the driven pulleys 15, 16, 17 and the drive pulley 13. The drive wire 14 is moved by rotation of the drive pulley 13, and the drive pulley 13 is rotated by rotation of the drive motor 11 via the drive transmission belt 12.

  One end side of the drive wire 14 is wound around the driven pulley 15, the driven pulley 17, the driven pulley 16, the drive pulley 13, and the like via a tight wire tension spring 18 and then fixed to the case 22. Here, the driven pulleys 16 and 17 are supported by the case 22 so as to rotate at fixed positions. The first carriage 3 is fixed to a part of the drive wire 14 and is movable in the left-right direction in the figure by being guided by guide means (not shown). The driven pulley 15 is pivotally supported by the second carriage 6. The second carriage 6 is guided by guide means (not shown) and is movable in the left-right direction in the drawing.

  The specific winding of the drive wire 14 is omitted because it is not the gist of the present invention. However, in essence, when the first carriage 3 moves to the right according to the rotation of the drive pulley 13, the driven pulley 15 serves as a moving pulley. It is wound by a generally known method so as to function and to move right at a speed of 1/2 of the first carriage 3.

  The CCD image sensor 20 that receives reflected light including image information and converts the image information into an electrical signal generates heat when driven. Normally, natural heat dissipation is supported, but recently, due to high image quality of scanner images and higher speeds due to clock-up, the ambient temperature of the CCD or the temperature of the CCD itself rises too much, leading to degradation of image quality and durability. ing.

  As shown in an enlarged view in FIG. 2, in this example, one end side of the heat conductor 26 made of a good heat conductor such as a copper plate is contacted to the outside of the casing of the CCD image sensor 20. I am letting. Thereby, the heat of the CCD image sensor 20 can be radiated through the heat conductor 26. For example, the other end side of the heat conductor 26 is fastened to the case 22 with a screw 24, and the above contact state is maintained.

  As in this example, the heat generated by the CCD image sensor 20 is dissipated through the heat conductor 26 with a simple configuration in which one end of the heat conductor 26 is brought into contact with the outside of the housing of the CCD image sensor 20, When a part of the heat conductor 26 is fixed to the case 22, the temperature of the CCD is lowered by dissipating heat to the atmosphere through the case 22. In this way, it is possible to prevent the ambient temperature of the CCD or the temperature of the CCD itself from being excessively increased, thereby causing deterioration of image quality and durability.

[2] Embodiment 2
As shown in enlarged views in FIGS. 3 and 4, in this example, an elastic body made of a good heat conductor in the shape of a rectangular parallelepiped, for example, a block piece 25 made of illuster resin, is brought into contact with the outside of the casing of the CCD image sensor 20. The opposite side of the contact portion is pressed by the heat conductor 26 whose end is bent in an L shape.

  That is, the block piece 25 is sandwiched between the outer side of the casing of the CCD image sensor 20 and the thermoelastic body 23 from both sides, so that the block piece 25 is in a uniform contact state with the CCD image sensor 20 and the heat conductor 26 by elasticity. Can be obtained and good heat dissipation can be performed.

[3] Embodiment 3
5 and 6, in this example, an elastic body made of a heat conductor bent in a C shape, for example, a leaf spring 27 is brought into contact with the outside of the casing of the CCD image sensor 20. The opposite side of the contact portion is pressed by the heat conductor 26 whose end is bent in an L shape.

  One leaf spring 27 may be provided, but a better contact state can be obtained by providing a plurality of leaf springs 27 as shown in FIG. Further, if the leaf spring 27 is appropriately formed with a slit, the degree of bending can be adjusted. As a result, the leaf spring 27 can obtain a uniform contact state due to elasticity to the CCD image sensor 20 and the heat conductor 26, and can perform good heat dissipation.

[4] Embodiment 4
As shown in FIG. 7 in an enlarged manner, in this example, an elastic body made of a heat conductor, for example, a compression spring (extensible spring) 28 is brought into contact with the outside of the casing of the CCD image sensor 20, and this contact portion. The opposite side is pressed by a heat conductor 26 whose end is bent in an L shape. Although one compression spring 28 may be provided, a better contact state can be obtained by providing a plurality of compression springs in the same manner as the leaf spring 27 shown in FIG. Thereby, the elastic body 27 can obtain a uniform contact state due to elasticity to the CCD image sensor 20 and the heat conductor 26, and can perform good heat dissipation.

[5] Embodiment 5
The image reading apparatus described so far is used for an image forming apparatus equipped with the image reading apparatus. An example of this image forming apparatus will now be described. In FIG. 8, an image reading device 23 according to the present invention is mounted above the main body 100 of the digital copying machine. Further, on this image reading device 23, automatic document conveyance is freely opened and closed with the back side as a fulcrum. A device 400 is attached.

  The main body 100 is provided with a drum-shaped photoconductor 180 as an image carrier. Around the photosensitive member 180, in order from the charging device 190 arranged on the left side in the drawing in the rotational direction (counterclockwise direction) A of the photosensitive member 180, the developing device 72 on the lower side, the transfer device 73 on the right side, and the upper side. A cleaning device 74 is arranged.

  Among them, the developing device 72 uses a polymerized toner produced by a polymerization method as the toner, and attaches the polymerized toner using a developing roller to visualize the electrostatic latent image on the photoreceptor 180. Further, the transfer device 73 is configured by winding a transfer belt 77 between upper and lower rollers 75 and 76, and the transfer belt 77 is pressed against the peripheral surface of the photosensitive member 180 at the transfer position B.

  In FIG. 8, what is provided on the left side of the charging device 190 and the cleaning device 74 is a toner supply device 200 for supplying new toner to the developing device 72.

  Further, inside the main body 100, there is provided a sheet conveying device C that conveys the sheet S fed from the sheet cassette 61 of the sheet bank 300 from the lower side to the upper side through the transfer position B to the stack position. The sheet conveying apparatus C includes a supply path R1, a manual feed path R2, and a sheet conveyance path R.

  In the sheet conveyance path R, a registration roller 210 is provided at an upstream position of the photoreceptor 180. Further, a thermal fixing device 53 is provided at a downstream position of the photoreceptor 180.

  Further downstream of the heat fixing device 53, rollers 55A and 55B, a roller 56, a conveyor belt 57, a conveyor roller 58, and the like are arranged. The paper on which the image has been formed passes through these rollers and the like, and is discharged and stacked on a discharge stack portion (discharge position) 39.

  The main body 100 is provided with a switchback device 42 on the right side in the drawing. The switchback device 42 branches from the position of the discharge branch pawl 34 of the sheet conveyance path R, and again from the switchback position 44 and the reverse path R3 that guides the sheet to the switchback position 44 that includes the pair of switchback rollers 43. A sheet conveying apparatus D having a re-conveying path R4 that leads to the registration rollers 210 in the conveying path R is provided. The sheet conveying apparatus D includes a plurality of sheet conveying rollers 66 for conveying the sheet.

  A laser writing device 47 is provided on the left side of the developing device 72 in the drawing. The laser writing device 47 is provided with a laser light source (not shown), a scanning polygon mirror 48, a polygon motor 49, a scanning optical system 50 such as an fθ lens, and the like.

  The automatic document feeder 400 on the contact glass 10 is provided with a document setting table (not shown) at the document placement position and a document stack table (not shown) at the discharge position. In addition, a sheet conveyance device having a document conveyance path (not shown) that conveys a document sheet from a document setting table to a document stacking table through a reading position on the contact glass 10 of the image reading device 23 is provided. The sheet conveying apparatus includes a plurality of unillustrated sheet conveying rollers for conveying the original sheet.

  The sheet bank 300 includes therein a plurality of sheet cassettes 61 that store sheets S as sheet-like media, for example, transfer sheets, OHP films, and the like. Each sheet cassette 61 is provided with a call roller 62, a supply roller 63, and a separation roller 64, respectively. A supply path R1 leading to the sheet conveyance path R of the main body 100 is formed on the right side of the sheet cassette 61 provided in multiple stages. The supply path R1 is also provided with several sheet transport rollers 66 (sheet transport rotating body) for transporting the sheet.

  The main body 100 is provided with a manual feed unit 68 on the right side in the drawing. The manual feed tray 68 is provided in the manual feed section 68 so as to be freely opened and closed, and includes the above-described manual feed path R <b> 2 that guides the manual sheet set on the manual feed tray 67 to the sheet conveyance path R. Similarly, the manual feed tray 67 is provided with a calling roller 62, a supply roller 63, and a separation roller 64.

  When making a copy using this copying machine, a main switch (not shown) is turned on, and a document is set on a document setting table of the automatic document feeder 400. In the case of a book document, the automatic document feeder 400 is opened, the document is set directly on the contact glass 10 of the image reading device 23, and the automatic document feeder 400 is closed and pressed.

  When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is moved on the contact glass 10 through the document conveyance path by the sheet conveyance roller, and then the image reading device 23 is moved. Drives, reads the document content, and discharges it onto the document stacking table. On the other hand, when the document is set directly on the contact glass 10, the image reading device 23 is immediately driven.

  When the image reading device 23 is driven, the image reading device 23 moves the first carriage 3 along the contact glass 10, reflects light from the lamp 1 on the original surface on the contact glass 10, and reflects the reflected light. The light is reflected by a plurality of mirrors such as the first mirror 2, the second mirror 4, and the third mirror 5, passes through an imaging lens 19, is put into a CCD image sensor 20, and the document content is read by the image sensor 20.

  At the same time, the photosensitive member 180 is rotated by a photosensitive member driving motor (not shown). First, in the illustrated example, the surface is uniformly charged by a charging device 190 using a charging roller, and then the image reading device 23 described above. The laser writing device 47 irradiates a laser beam in accordance with the content of the read document and writes it with the laser writing device 47 to form an electrostatic latent image on the surface of the photosensitive member 180. Visualize the electrostatic latent image.

  At the same time when the start switch is pressed, the sheet S is sent out from the sheet cassette 61 corresponding to the selected size in the plurality of sheet cassettes 61 provided in multiple stages in the sheet bank 300 by the calling roller 62, followed by the supply roller 63, separation While being separated and conveyed one by one by the roller 64, it is put into the supply path R 1, conveyed by the sheet conveying roller 66 to the sheet conveying path R, and abutted against the registration roller 210 and stopped. Then, the registration roller 21 is rotated in synchronization with the rotation of the toner image visualized on the photosensitive member 180 described above, and is sent to the right side of the photosensitive member 18.

  Alternatively, the manual feed tray 67 of the manual feed unit 68 is opened, the manual sheet set on the manual feed tray 67 is sent out by the calling roller 62, and separated and conveyed one by one by the subsequent supply roller 63 and separation roller 64. The sheet is fed into the manual feed path R2, is conveyed by the sheet conveying roller 66, is guided to the sheet conveying path R, and is similarly fed to the right side of the photosensitive member 18 by the registration roller 21 in synchronization with the rotation of the photosensitive member 18.

  Then, the toner image on the photosensitive member 180 is transferred to the sheet S fed to the right side of the photosensitive member 180 at the transfer position B by the transfer device 73 in the illustrated example, thereby forming an image. Residual toner on the photosensitive member 180 after image transfer is removed and cleaned by a cleaning device 74, and a residual potential on the photosensitive member 18 is removed by a neutralizing device (not shown) to prepare for the next image formation starting from the charging device 19. .

  On the other hand, the sheet S after the image transfer is conveyed by the transfer belt 77, detected by a sensor (not shown), and then put into the thermal fixing device 53, and passed between the heated fixing roller 51 and the pressure roller 52. The toner image on the paper S is fixed by applying heat and pressure by them. Then, it discharges | emits on the discharge | stacking stack part 39, and stacks there.

  When images are transferred on both sides of the paper S, the discharge branch claw 34 is switched. Then, the sheet-like medium having the toner image transferred on the surface thereof is placed from the sheet conveyance path R to the reverse path R3, conveyed by the sheet conveyance roller 66 to the switchback position 44, and switched back by the switchback roller 43. The sheet is put in the re-conveying path R4, reversed, conveyed by the sheet conveying roller 66, guided again to the sheet conveying path R, and the image is transferred to the back surface of the sheet in the same manner as described above.

1 is a partial cross-sectional front view illustrating an overall configuration of an image reading apparatus according to the present invention. It is a partial expanded sectional view of the image reading apparatus concerning this invention. It is a partial expanded sectional view of the image reading apparatus concerning this invention. It is the perspective view which illustrated the elastic body concerning this invention with CCD. It is a partial expanded sectional view of the image reading apparatus concerning this invention. It is the perspective view which illustrated the elastic body concerning this invention with CCD. It is a partial expanded sectional view of the image reading apparatus concerning this invention. 1 is a diagram illustrating a configuration of an image forming apparatus equipped with an image reading apparatus according to the present invention.

Explanation of symbols

20 CCD image sensor 26 Thermal conductor

Claims (6)

In a digital image reading apparatus that converts optical information of an image obtained by scanning a document into an electrical signal using a CCD image sensor.
An image reading apparatus characterized in that a heat conductor is brought into contact with the outside of the casing of the CCD image sensor. The image reading apparatus according to claim 1.
An image reading apparatus, wherein a part of the heat conductor is fixed to a case of the image reading apparatus. The image reading apparatus according to claim 1 or 2,
The image reading apparatus according to claim 1, wherein at least a contact portion between the thermal conductor and the outside of the casing of the CCD image sensor is an elastic body.   4. The image reading apparatus according to claim 1, wherein the elastic body is a leaf spring.   4. The image reading apparatus according to claim 1, wherein the elastic body is a compression spring. In an image forming apparatus equipped with an image reading device,
An image forming apparatus according to claim 1, wherein the image reading apparatus is one according to claim 1.

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