JP5622672B2 - Image reading apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an image by irradiating a document by a side light system that guides light emitted from an LED light source disposed at one end in the main scanning direction in a main scanning direction by a light guide, and a copy including the image reading apparatus. The present invention relates to an image forming apparatus such as a printer.

  An image forming apparatus such as a copying machine that forms an image on a sheet by an electrophotographic method is provided with an image reading apparatus for optically reading a document image. In recent years, a light source of this image reading apparatus has been conventionally used. LED light sources have been used in place of xenon lamps and cold cathode lamps.

  Some image reading apparatuses using LED light sources employ a side light system that guides light emitted from an LED light source disposed at one end in the main scanning direction in the main scanning direction by a light guide. In order to obtain a light amount necessary for image reading in the entire main scanning direction in the apparatus, a high light amount LED light source is required. For this reason, recently, LEDs have been developed that can obtain a high amount of light by incorporating a plurality of light emitting elements in one package and flowing a large current, and such LEDs are used as a light source of an image reading apparatus employing a sidelight system. Is suitable.

  However, when a large current type LED is used as the light source of the image reading apparatus, the LED light emitting surface becomes very hot as compared with a normal LED that is turned on by passing a current of about 20 to 30 mA. In addition, in the image reading apparatus adopting the side light method, the light emitting surface of the LED light source and the incident surface of the light guide end are in close contact with each other in order to make the light emitted from the LED light source enter the light guide without leaking. The light guide becomes hot due to heat from the LED light source. In particular, when the LED light source is continuously turned on and continuously printed, heat at the time of continuous printing in the image forming unit is transmitted to the image reading device, and the temperature of the light guide may exceed the heat resistance temperature.

  By the way, as a countermeasure against heat in an image reading apparatus that employs a side light system using a large current type LED light source, Patent Document 1 proposes a configuration in which a heat dissipation member and a cooling fin are provided on a substrate on which an LED is mounted. 2 proposes a configuration in which a solid connection member having a high heat resistance is interposed between an LED light source and a light guide.

JP 2010-087809 A JP 2010-027419 A

  However, in the configuration proposed in Patent Document 1, there is a problem in that the apparatus is increased in size by providing a heat radiating member and a cooling fin, resulting in an increase in cost. Further, in the configuration proposed in Patent Document 2, since the connecting member is solid, heat from the LED light source is transmitted to the light guide through this connecting member, so that the light guide becomes high temperature and the connecting member is There is a problem that the cost is increased due to the high price.

  The present invention has been made in view of the above problems, and the object of the present invention is to suppress the heat transfer from the high light quantity LED light source to the light guide with a simple configuration without causing an increase in cost. An object of the present invention is to provide an image reading apparatus capable of suppressing an increase and an image forming apparatus including the image reading apparatus.

  In order to achieve the above object, the invention according to claim 1 is an LED light source disposed at one end in the main scanning direction and a transparent light guide for guiding light incident from an incident surface facing the LED light source in the main scanning direction. In an image reading apparatus that irradiates a document by a side light method and reads an image thereof, a hollow light guide member is interposed between the LED light source and an incident surface of the light guide.

  According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a light collecting member that condenses light leaking from the light guide over the entire region in the main scanning direction.

  According to a third aspect of the present invention, in the second aspect of the present invention, the substrate mounting portion for mounting the substrate of the LED light source and the light guide member as a substrate mounting member are integrally formed of a material having higher heat resistance than the light guide. In addition, the condensing member is made of a material having lower heat resistance than the substrate mounting member.

  According to a fourth aspect of the present invention, in the second aspect of the present invention, the substrate mounting portion for mounting the substrate of the LED light source and the light collecting member are integrally formed of a material having lower heat resistance than the light guide member, The light guide member is made of a material having higher heat resistance than the light guide.

  According to a fifth aspect of the present invention, in the second aspect of the present invention, the substrate mounting portion for attaching the substrate of the LED light source, the light guide member, and the light collecting member are integrated with a material having higher heat resistance than the light guide. It is characterized by comprising.

  An image forming apparatus according to a sixth aspect includes the image reading apparatus according to any one of the first to fifth aspects.

  According to the first aspect of the present invention, since a heat insulating layer of air is formed between the LED light source and the incident surface of the light guide by the hollow light guide member, a large light amount LED light source is used. However, heat transfer from the LED light source to the light guide is blocked by the air layer, and the temperature rise of the light guide is suppressed, and the durability of the light guide is enhanced. In addition, such an effect can be obtained with a simple configuration in which a hollow light guide member is interposed between the LED light source and the incident surface of the light guide, and the light guide material has high heat resistance and is expensive. Since it is not necessary to use anything, the cost of the apparatus is not increased.

  According to the second aspect of the present invention, since the light leaking from the light guide is condensed by the light collecting member over the entire region in the main scanning direction and used for irradiating the original, the light emitted from the LED light source is used. Efficiency is increased.

  According to the third aspect of the present invention, since the board mounting portion and the light guide member are integrally formed as a board mounting member, the light emitting surface of the LED light source and the light guide are replaced by replacing the board mounting member and the LED light source. The distance between the incident surfaces and the amount of reading light of the original can be changed, and the light guide and the condensing member can be commonly used for different image reading apparatuses. In addition, since the condensing member is made of a material having lower heat resistance than that of the substrate mounting member, the material cost of the condensing member can be suppressed to a low cost.

  According to invention of Claim 4, since the board | substrate attachment part and the condensing member were integrally comprised with the material whose heat resistance is lower than a light guide member, the material cost of these board | substrate attachment parts and a condensing member was suppressed low. Cost can be reduced. Moreover, since the light guide member is made of a material having higher heat resistance than that of the light guide, the durability of the light guide member disposed close to the LED light source that is at a high temperature is enhanced.

  According to the fifth aspect of the present invention, since the board mounting portion, the light guide member, and the light collecting member are integrally formed of a material having higher heat resistance than the light guide, the number of parts and the number of assembly steps can be reduced.

  According to the sixth aspect of the present invention, since the original image is read with high accuracy using the high light quantity LED light source in the image reading apparatus, a high quality image can be stably obtained.

1 is a side sectional view of an image forming apparatus according to the present invention. 1 is a partial perspective view of a main part of an image reading apparatus according to the present invention. 1 is a partial cross-sectional view of a main part of an image reading apparatus according to the present invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a side sectional view of an image forming apparatus according to the present invention. The illustrated image forming apparatus 1 is a monochrome copying machine, and includes an image reading device 2 according to the present invention at the upper part of the apparatus main body 1A. A discharge tray 3 is provided below the discharge tray 3. An image forming unit 4 is disposed inside the apparatus main body 1A, and a paper feeding unit 5 is disposed below the image forming unit 4.

  The image reading device 2 includes an LED light source 6 disposed at one end in the main scanning direction (left and right direction in FIG. 1), and a transparent light that guides light incident from an incident surface 7a facing the LED light source 6 in the main scanning direction. An apparatus for reading an image by irradiating a document by a side light system using a guide 7, and the LED light source 6 and the light guide 7 are supported so as to be able to reciprocate in the sub-scanning direction (direction perpendicular to the paper surface of FIG. 1). Although not shown, the image reading device 2 includes an imaging lens that forms an image of the reflected light reflected from the document, and a photoelectric conversion element that converts the optical image formed by the imaging lens into an electrical signal and reads the electrical signal. Is provided.

  The image forming unit 4 forms an image by an electrophotographic method. The image forming unit 4 is a photosensitive drum 8 as an image carrier that is rotatably arranged, a charger 9 and a laser scanner unit ( LSU) 10, a developing device 11, a transfer roller 12, and a cleaning device 13.

  The paper feed unit 5 includes a detachable paper feed cassette 14 and a pick roller 15 and a paper feed roller 16 disposed in the vicinity thereof. Here, a plurality of sheets S are stacked and accommodated in the sheet feeding cassette 14, and the sheets S in the sheet feeding cassette 14 are sequentially taken out from the upper one by the pick roller 15, and are fed by the sheet feeding roller 16. It is sent out to the paper conveyance path P.

  The paper transport path P extends upward from the paper supply unit 5 to the paper discharge tray 3, and the registration roller 17, the transfer roller 12, the fixing device 18, and the transport of the paper transport path P from below. A roller 19 and a paper discharge roller 20 are sequentially arranged.

  Next, an image forming operation of the image forming apparatus 1 configured as described above will be described.

  When the image forming operation is started, in the image forming unit 4, the photosensitive drum 8 is rotationally driven in the arrow direction (clockwise) in FIG. 1 by a driving unit (not shown), and the surface thereof is set to a predetermined potential by the charger 9. Uniformly charged. In the image reading device 2, the original image is read as described later, and a laser beam based on an electrical signal transmitted from the image reading device 2 is output from the laser scanner unit 10 to expose the surface of the photosensitive drum 8. When scanned, an electrostatic latent image corresponding to image information is formed on the photosensitive drum 8. Then, the electrostatic latent image formed on the photosensitive drum 8 is developed by the developing device 11 using toner as a developer to be visualized as a toner image.

  Further, the paper S accommodated in the paper feed cassette 14 of the paper feed unit 5 is picked up from the uppermost one by the pick roller 15 and sent out to the paper transport path P by the paper feed roller 16. Then, the paper S sent out to the paper conveyance path P in this way is conveyed to the registration roller 17 through the paper conveyance path P and is temporarily put in a standby state in the registration roller 17, and then the toner on the photosensitive drum 8. The image is supplied to the image forming unit 4 at a predetermined timing synchronized with the image.

  In the image forming unit 4, the sheet S supplied to the transfer nip between the photosensitive drum 8 and the transfer roller 12 is conveyed while being pressed against the photosensitive drum 8 by the transfer roller 12, so that the surface thereof is exposed to light. The toner image on the drum 8 is transferred. Then, the sheet S on which the toner image is transferred is conveyed to the fixing device 18, and is heated and pressurized in the process of passing through the fixing nip of the fixing device 18 to receive the fixing of the toner image. The toner remaining on the surface of the photosensitive drum 8 (transfer residual toner) after the transfer of the toner image onto the paper S is removed by the cleaning device 13, and the photosensitive drum 8 whose surface has been cleaned is prepared for the next image forming operation. .

Thus, the sheet S on which the toner image is fixed on the surface by the fixing device 18 is conveyed by the conveying roller 19 to the sheet discharging roller 20 along the sheet conveying path P, and the sheet discharging tray 3 by the sheet discharging roller 20. And the series of image forming operations is completed.
[Image reading device]
Next, a characteristic configuration of the image reading apparatus 2 according to the present invention will be described with reference to FIGS.

  2 is a partial perspective view of the main part of the image reading apparatus according to the present invention. FIG. 3 is a partial cross-sectional view of the main part of the image reading apparatus. As shown in FIG. The LED light source 6 is configured by mounting an LED chip 6b on a substrate 6a, and is attached to the substrate attachment portion 21 so as to overlap from the outside. The LED chip 6 b of the LED light source 6 faces a circular cavity 21 a formed in the board attachment 21, and a hollow (cylindrical) light guide is provided in the cavity 21 a of the board attachment 21. The member 22 is fitted. Therefore, the incident surface 7a at one end in the main scanning direction of the light guide 7 is disposed to face the LED chip 6b of the LED light source 6 via the light guide member 22, and the LED light source 6 and the incident surface 7a of the light guide 7 are arranged. A hollow light guide member 22 is interposed therebetween. Here, the light guide member 22 is formed in a cylindrical shape with a white resin having higher heat resistance than the light guide 7.

  A light condensing member 23 is provided below the light guide 7 for condensing light leaking from the light guide 7 over the entire region in the main scanning direction. The board mounting portion 21, the LED light source 6, the light guide 7, and the light collecting member 23 mounted on the substrate mounting portion 21 are supported by a carriage (not shown) so as to reciprocate in the sub-scanning direction.

  Thus, when a current is supplied to the LED chip 6b of the LED light source 6, the LED chip 6b is activated to emit light, and part of the light reaches the incident surface 7a of the light guide 7 directly, The light reaches the incident surface 7 a of the light guide 7 while being reflected by the inner surface of the light guide member 22. The light reaching the incident surface 7a of the light guide 7 enters the light guide 7 from the incident surface 7a, propagates in the main scanning direction while reflecting the light guide 7, and a part of the light guide 7 is reflected. The light is emitted upward from the exit surface 7b of the light guide 7 toward the original and is irradiated on the original. The light leaking outside the light guide 7 is condensed by the light collecting member 23 and re-enters the light guide 7, and is emitted upward from the light exit surface 7b of the light guide 7 toward the original. Is irradiated.

  As described above, the light emitted from the LED light source 6 is emitted toward the original while being guided in the main scanning direction by the light guide 7, and the original is scanned in the main scanning direction by this light. As the guide 7 moves in the sub-scanning direction, the document is scanned in the sub-scanning direction. As described above, when the original is scanned in the main scanning direction and the sub-scanning direction by the light emitted from the light guide 7, the reflected light reflected by the original is imaged by an imaging lens (not shown) and is connected by the imaging lens. The imaged optical image is read by a photoelectric conversion element (not shown) and converted into an electric signal.

  As described above, in the image reading apparatus 2 according to the present invention, since the heat insulating layer of air is formed between the LED light source 6 and the incident surface 7a of the light guide 7 by the hollow light guide member 22, the LED light source 6, even when a light source having a large light quantity is used, heat transfer from the LED light source 6 to the light guide 7 is blocked by the air layer, and the temperature rise of the light guide 7 is suppressed, so that the durability of the light guide 7 is improved. Sexuality is enhanced. Further, such an effect can be obtained by a simple configuration in which a hollow light guide member 22 is interposed between the LED light source 6 and the incident surface 7a of the light guide 7, and the material of the light guide 7 is heat resistant. Since it is not necessary to use an expensive and expensive device, the cost of the document reading device 2 is not increased.

  Furthermore, since the light leaking from the light guide 7 is condensed over the entire region in the main scanning direction by the light collecting member 23 and used for irradiating the document, the utilization efficiency of the light emitted from the LED light source 6 is improved.

  In the image forming apparatus 1 shown in FIG. 1, since the original image is read with high accuracy by the image reading apparatus 2 using the high light quantity LED light source 6, a high-quality image can be stably obtained.

  By the way, in the above embodiment, although the light guide member 22 was comprised as an independent component, it is more heat-resistant than the light guide 7 by making the board | substrate attachment part 21 and the light guide member 22 which attach the board | substrate 6a of the LED light source 6 into a board | substrate attachment member. The condensing member 23 may be made of a material having lower heat resistance than the substrate mounting member. By adopting such a configuration, the distance between the light emitting surface of the LED light source 6 and the incident surface 7a of the light guide 7 and the amount of original reading light can be changed by replacing the board mounting member and the LED light source 6 as a set. The light guide 7 and the light collecting member 23 can be used in common for different image reading apparatuses 2. Moreover, since the condensing member 23 is made of a material having lower heat resistance than that of the substrate mounting portion 21, the material cost of the condensing member 23 can be suppressed to a low cost.

  Alternatively, the substrate mounting portion 21 and the light collecting member 23 may be integrally formed of a material having lower heat resistance than the light guide 7, and the light guide member 22 may be formed of a material having higher heat resistance than the light guide 7. . By adopting such a configuration, it is possible to reduce the cost by keeping the material costs of the substrate mounting portion 21 and the light collecting member 23 low. Further, since the light guide member 22 is made of a material having higher heat resistance than that of the light guide 7, durability of the light guide member 22 disposed close to the LED light source 6 that is at a high temperature is enhanced.

  Furthermore, the substrate mounting portion 21, the light guide member 22, and the light collecting member 23 may be integrally formed of a material having higher heat resistance than the light guide 7. By adopting such a configuration, it is possible to reduce the number of parts and the number of assembly steps.

  In this embodiment, the embodiment in which the present invention is applied to a monochrome copying machine and an image reading apparatus provided in the monochrome copying machine has been described. However, the present invention is not limited to a monochrome or color facsimile machine other than a copying machine. Needless to say, the present invention can be similarly applied to any other image forming apparatus such as a multifunction peripheral and an image reading apparatus provided therein.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1A Image forming apparatus main body 2 Image reading apparatus 3 Paper discharge tray 4 Image forming part 5 Paper feeding part 6 LED light source 6a LED light source board 6b LED chip 7 Light guide 7a Light guide incident surface 7b Light guide emission Surface 8 Photosensitive drum 9 Charger 10 Laser scanner unit (LSU)
DESCRIPTION OF SYMBOLS 11 Developing device 12 Transfer roller 13 Cleaning device 14 Paper feed cassette 15 Pick roller 16 Paper feed roller 17 Registration roller 18 Fixing device 19 Transport roller 20 Paper discharge roller 21 Substrate attachment portion 21a Substrate attachment portion cavity portion 22 Light guide member 23 Collection Optical member P Paper transport path S Paper

Claims (2)

Image reading that reads an image by irradiating a document by a side light method using an LED light source disposed at one end in the main scanning direction and a transparent light guide that guides light incident from an incident surface facing the LED light source in the main scanning direction In the device
A hollow light guide member is interposed between the LED light source and the incident surface of the light guide ,
A light collecting member for collecting light leaking from the light guide over the entire main scanning direction is provided,
The substrate mounting portion for attaching the substrate of the LED light source and the light collecting member are integrally formed of a material having a lower heat resistance than the light guide member, and the light guide member is formed of a material having a higher heat resistance than the light guide. image reading apparatus characterized by constituting the. An image forming apparatus comprising the image reading apparatus according to claim 1 .

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