JP2012242749A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing adverse effect due to heat from fixing means on a unit on an upper side of the fixing means and preventing a volatile organic compound generated from the fixing means and ozone leaking from charging means from flowing to peripheral parts to efficiently deliver the compound and ozone to exhaust fan.SOLUTION: An image forming apparatus 15 includes: a photoreceptor 3; charging means 4; optical writing means 1; developing means 2; transfer means 11; and fixing means 6. In the image forming apparatus 15, the optical writing means 1 is arranged on an upper side of the fixing means 6 and includes exhaust heat means 7 for discharging radiation heat generated by the fixing means 6 to the outside of a machine, and a heat shielding member 8 for preventing the radiation heat from transferring to the optical writing means 1 is provided over the overall width of the image forming apparatus 15 between the optical writing means 1 and the exhaust heat means 7.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus having a fixing device that fixes a toner image onto transfer paper by heat.

  Conventionally, an electrostatic latent image is formed on a photosensitive member by an optical writing unit, and the electrostatic latent image is visualized by a developing unit to form a toner image, and then the toner image on the photosensitive member is transferred to a transfer sheet. An image forming apparatus such as a copying machine, a facsimile machine, a printer, or a multi-function machine is known in which a toner image on a transfer paper is fixed by heat and pressure after a fixing unit. In such an image forming apparatus, in order to prevent the lens provided in the optical writing unit from being deformed by heat generated by the fixing unit and thereby causing deterioration in image quality, fixing is performed by surrounding the optical writing unit with a sheet metal. A technique for blocking the influence of heat from the means is disclosed in, for example, “Patent Document 1”.

  In addition, the toner is scattered due to the problem that the distance between the fixing unit and the developing unit is narrow due to the increase in the temperature of the developer, and the interval between the fixing unit and the cleaning unit is narrow. In order to solve the problem that the toner recovery mechanism is locked due to the fixing, a technique for discharging heat from the fixing unit by a shielding member, a fan, and a duct provided only at the upper part of the unit is disclosed in, for example, “Patent Document 2”. Is disclosed.

  In each of the above-described technologies, there is no configuration in which the entire unit provided above the fixing unit such as the optical writing unit and the image reading unit is shielded from the heat from the fixing unit, and a gap or the like is generated between the units, resulting in a heat insulating effect. There is a problem that the efficiency of. Further, there is a problem that volatile organic compounds generated from the fixing unit and ozone leaking from the charging unit cannot be efficiently led to the exhaust fan.

  The present invention solves the above-mentioned problems and can prevent adverse effects due to heat from the fixing unit on the unit above the fixing unit, and can also prevent volatile organic compounds generated from the fixing unit and charging. An object of the present invention is to provide an image forming apparatus capable of preventing ozone leaking from the means from flowing out to the peripheral portion and efficiently sending it to an exhaust fan.

  According to the first aspect of the present invention, there is provided a photosensitive member, a charging unit that charges the photosensitive member, a light writing unit that forms an electrostatic latent image on the photosensitive member, and a toner that visualizes the electrostatic latent image. An image forming apparatus comprising: a developing unit that forms an image; a transfer unit that transfers a toner image on the photoconductor to a transfer material; and a fixing unit that fixes the toner image transferred onto the transfer material by heat. The optical writing means is disposed above the fixing means and has heat exhausting means for exhausting radiant heat generated from the fixing means to the outside of the apparatus, and the optical writing means is disposed between the optical writing means and the exhaust heat means. A heat shield member for preventing radiant heat from reaching the optical writing means is provided over the entire width of the apparatus.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the heat shield member is constituted by a hollow metal member.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the heat shield member is formed of a non-metallic heat-resistant member.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the heat shield member further extends to an exterior member of the apparatus, and outside air is taken into the exterior member. And a vent hole that can be discharged is provided.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the heat shield member further includes a heat insulating member.

  According to the present invention, even when the radiant heat generated from the fixing unit is not completely exhausted by the exhaust heat unit, the radiant heat is generated by the heat shielding member disposed between the fixing unit, the optical writing unit, and the image reading unit. Ozone that leaks from the volatile organic compound generated from the fixing means and from the charging means, while being able to prevent the radiation writing and image reading means disposed above the fixing means from being adversely affected by radiant heat. Can be prevented from flowing out to the peripheral portion, the intake efficiency of the heat exhausting means can be improved, and a good image forming operation can be performed.

1 is a schematic front view of an image forming apparatus to which an embodiment of the present invention can be applied. 1 is a schematic front view of an image forming unit that employs a first embodiment of the present invention. It is the schematic explaining the thermal insulation member used for the 1st Embodiment of this invention. It is the schematic explaining the 2nd Embodiment of this invention.

  FIG. 1 shows an image forming apparatus to which an embodiment of the present invention can be applied. In the figure, the image forming apparatus 15 is a monochrome machine. However, as an image forming apparatus to which the present invention can be applied, other image forming apparatuses such as a full-color copying machine, a printer, a single facsimile, or a copying machine and a printer. It may be a multifunction device such as a multifunction device. The image forming apparatus 15 can form an image on a sheet-like recording medium using, in addition to plain paper generally used for copying or the like, any of OHP sheets, thick paper such as cards and postcards, and envelopes. The image forming apparatus 15 is configured to be able to form an image on both sides of a transfer sheet as a recording medium.

  The image forming apparatus 15 includes a photosensitive drum 3 that is an image carrier, and the photosensitive drum 3 is rotatably supported by a frame (not shown) of the apparatus main body. Around the photosensitive drum 3, there are a charge eliminating device (not shown), a charging means 4 having a charging roller (not shown) for AC charging, a developing means 2 for developing with a two-component developer containing toner and a carrier, and a transfer means. The transfer belt 11 and the cleaning device 5 are provided as electrophotographic process means. These are well-known configurations. For example, the developing unit 2 detects a developing roller that is a developer carrying member disposed opposite to the photosensitive drum 3, a screw that stirs and conveys the developer, and a toner concentration in the developer. A toner concentration sensor for supplying toner to the developing means 2 in accordance with the output of the toner concentration sensor, and a developing roller having a magnet fixed to the developing device main body side and a magnet of the magnet. And a sleeve rotatably supported on the outside.

  The components around the photosensitive drum 3, the cleaning device 5, the static eliminating device, the charging unit 4, the developing unit 2, and the photosensitive drum 3 are integrated to form a process cartridge. The process cartridge is configured to be detachable toward the front side in FIG. 1 with a front panel (not shown) opened. Such a process cartridge can be handled as a replacement part, so that maintainability is remarkably improved. The transfer belt 11 can move in the direction of the arrow while facing the photosensitive drum 3, and a predetermined transfer bias is applied from a power source (not shown). A visible toner image formed on the surface of the photosensitive drum 3 is transferred onto a transfer sheet conveyed on the transfer belt 11 that is moved by the action of a transfer bias.

  The image forming apparatus 15 has an optical writing unit 1, which is a latent image forming unit disposed opposite to the photosensitive drum 3, in the apparatus main body. The optical writing unit 1 includes a light source such as a semiconductor laser (not shown), a polygon mirror, an fθ lens, a reflection mirror, and the like, and the light source is controlled to emit light by a control unit (not shown) based on data corresponding to an image to be formed. In both cases, the polygon mirror is rotationally driven and controlled, whereby the surface of the rotating photosensitive drum 3 is irradiated with laser light to form an electrostatic latent image.

  Above the optical writing means 1, a contact glass (not shown) for placing the document, a light source for irradiating light on the document placed on the contact glass, and a first light for reflecting light reflected on the document from the light source are reflected. A first traveling body (not shown) that includes a reflector and travels in the left-right direction in FIG. 1, a second traveling body (not illustrated) that includes a second reflector that reflects light reflected by the first reflector, and a second traveling body. An image reading device 17 having an imaging lens (not shown) that forms an image of light from the body, a reading sensor (not shown) that receives the light passing through the imaging lens and reads the contents of the document is provided.

  A sheet feeding device 12 capable of stacking a large number of transfer sheets fed toward the transfer belt 11 is provided below the main body of the apparatus, and the sheet feeding device 12 is fed above the sheet feeding device 12. A registration roller pair 14 that feeds the transfer paper toward the transfer belt 11 at a predetermined timing that matches the toner image formation timing, and a sensor (not shown) that detects that the leading edge of the transfer paper has reached the registration roller pair 14 are arranged. It is installed. The sheet feeding device 12 is disposed below the main body of the apparatus so as to accommodate a plurality of transfer sheets in a stacked state. The sheet feeding device 12 is fed by a paper feed cassette that can store a plurality of transfer papers, a paper feed roller that contacts and feeds the uppermost transfer paper contained in the paper feed cassette, and a paper feed roller. A separation roller for separating the transfer paper to be fed into only one sheet, an attachment / detachment sensor (not shown) for detecting that the paper feed cassette is attached to and detached from the apparatus main body, and the like are provided. When the paper feed roller is driven to rotate at a predetermined timing, the uppermost transfer paper in the paper feed cassette separated by the separation roller is fed to the paper transport path, and the fed transfer paper is transferred to the registration roller pair. Pause between 14 rollers.

  In FIG. 1, a fixing unit 6 for fixing the toner image to the transfer paper on which the toner image is transferred is disposed on the left side of the transfer belt 11. The fixing means 6 is a well-known heat-pressure-fixing system having a heating roller 6a having a heater inside and a pressure roller 6b in pressure contact with the heating roller 6a. The toner image transferred on the transfer paper is transferred to the transfer paper by heat and pressure. To settle against. Disposed on the left side of the fixing unit 6 is a paper discharge roller 16 for discharging the fixed transfer paper to the outside of the apparatus main body, and below the paper discharge roller 16 is a double-sided unit 20 used for double-sided image formation. Is arranged.

  An exhaust fan 7 is disposed above the fixing unit 6 and below the optical writing unit 1 as exhaust heat unit for exhausting radiant heat generated from the heating roller 6 to the outside of the apparatus. The exhaust fan 7 communicates with the outside of the apparatus main body so as to exhaust the air inside the apparatus main body to the outside of the apparatus, and is configured to always operate when the image forming apparatus 15 is operated.

  Further, a guide member 21 that guides the ozone generated from the charging means 4 to the exhaust fan 7 is provided, and the exhaust efficiency of ozone is improved. Similarly, a guide member may be provided in the vicinity of the fixing unit 6 so that a volatile organic compound generated from the fixing unit is guided to the exhaust fan 7. By these configurations, unnecessary substances such as ozone and volatile organic compounds can be efficiently used. Thus, it is possible to lead to the exhaust fan 7, and it is possible to construct a favorable environmental condition during the image forming operation.

  Further, the apparatus main body of the image forming apparatus 15 includes a driving device (not shown) that drives the photosensitive drum 3 to rotate, a CPU that controls the overall operation of the image forming apparatus 15, a memory that functions as a storage unit, and the like. A control unit, a power supply unit that supplies power to each component of the image forming apparatus 15 from an external power supply, and the like are provided.

  In the image forming apparatus 15 described above, when a signal indicating that an image is to be formed is input by pressing a start switch (not shown) or the like, data corresponding to the image to be formed by reading the document in the image reading apparatus 17. Is acquired and input to the control means. Further, the transfer belt 11 is driven to run, and the photosensitive drum 3 is driven to rotate clockwise in FIG.

  The surface of the photosensitive drum 3 is uniformly charged by the charging unit 4 as it rotates, and is exposed to laser light from the optical writing unit 1 that is driven and controlled by the control unit based on image data to be formed. An electrostatic latent image is formed on the surface. The formed electrostatic latent image is visualized by the toner of the developing means 2, and a toner image is formed on the surface of the photosensitive drum 3. On the other hand, a sheet of transfer paper is separated and fed from the sheet feeding device 12 in response to the input of the image forming signal, and the separated and fed transfer paper is temporarily stopped in a state of being abutted between the rollers of the registration roller pair 14. Is done.

  The registration roller pair 14 is rotationally driven in accordance with the timing at which the toner image formed on the photosensitive drum 3 reaches the transfer belt 11, and the transfer paper fed from the registration roller pair 14 is sent to the transfer belt 11. . The transferred transfer paper is pressed against the photosensitive drum 3 by the transfer belt 11, and the toner image on the photosensitive drum 3 is transferred by the pressure and the bias voltage. The transfer paper on which the toner image has been transferred is conveyed by the transfer belt 11 and sent to the fixing means 6, and the toner image is fixed on the transfer paper by the action of heat and pressure of the heating roller 6 a and the pressure roller 6 b. .

  The transfer sheet that has passed through the fixing unit 6 is discharged onto a discharge tray (not shown) by a discharge roller 16 and stacked. In the case of double-sided image formation, the transfer paper that has been fixed on one side is conveyed again toward the registration roller pair 14 via the double-side unit 20. The photosensitive drum 3 is prepared for the next charging by the charging unit 4 after the transfer residual toner remaining after the transfer is removed by the cleaning device 5 and then discharged by the charge removing device.

  However, in the image forming apparatus 15 described above, the radiant heat from the fixing means 6 is interposed between the optical writing means 1 and the image reading apparatus 17 and the fixing means 6 as described in the section “Problems to be Solved by the Invention”. The exhaust fan 7 alone is not efficient in the heat insulation effect, and the exhaust fan 7 efficiently eliminates volatile organic compounds generated from the fixing unit 6 and ozone leaking from the charging unit 4, particularly ozone from the charging unit 4. There is a problem that it cannot be led to.

  In order to solve this problem, in the first embodiment of the present invention, a heat shield member 8 is disposed between the optical writing means 1 and the exhaust fan 7 as shown in FIG. As shown in FIG. 3, the heat shield member 8 made of a hollow metal plate is sandwiched between a front plate 9 and a rear plate 10 of the apparatus main body and is sandwiched between a left plate and a right plate (not shown). As described above, the image forming apparatus 15 is provided over the entire width. A part of the image forming apparatus 15 is provided with a translucent portion 8 a for irradiating the photosensitive drum 3 with the laser light from the optical writing unit 1. The heat shield member 8 is fixed to the apparatus main body of the image forming apparatus 15 by a known method such as screwing or welding.

  With this configuration, even if the radiant heat generated from the fixing unit 6 is not completely exhausted by the exhaust fan 7, the radiant heat is a heat shield disposed between the fixing unit 6 and the optical writing unit 1 and the image reading unit 17. Volatile organic compounds generated by the fixing means can be prevented from being adversely affected by radiant heat on the optical writing means 1 and the image reading means 17 that are absorbed and blocked by the member 8 and disposed above the fixing means 6. In addition, ozone leaking from the charging means can be prevented from flowing out to the peripheral portion, and the intake efficiency of the exhaust fan 7 can be improved and a good image forming operation can be performed.

  FIG. 4 shows a second embodiment of the present invention. Compared with the first embodiment, the second embodiment takes outside air into the main body of the left and right plates 18 and 19 constituting the main body of the image forming apparatus 15 as exterior members. The only difference is that it has vent holes 18a and 19a that can be discharged, and the other configurations are the same. With this configuration, air enters and exits from the vents 18a and 19a with respect to the apparatus main body of the image forming apparatus 15. Therefore, the heat shield member 8 is efficiently cooled by the air, and heat is accumulated inside the apparatus main body. Occurrence of problems such as deformation of members can be prevented.

  As a modification of the second embodiment, as shown in FIG. 4, the heat insulating member 13 is provided on the lower side of the heat shield member 8, that is, on the exhaust fan 7 side, so that it is provided above the fixing unit 6. It is possible to reliably prevent the radiant heat from affecting the optical writing unit 1 and the image reading unit 17, and it is possible to prevent various problems caused by deformation of various members due to the radiant heat, and to continue good image forming operations. Can be done automatically.

  In each of the above embodiments and modifications, the heat shield member 8 is made of a hollow metal plate and fixed to the apparatus body by screwing or welding. However, the heat shield member is hollow. It is not limited to the one made of the metal plate, but may be constituted by a solid metal member or a non-metal heat-resistant member such as a resin.

DESCRIPTION OF SYMBOLS 1 Optical writing means 2 Developing means 3 Photosensitive drum 4 Charging means 6 Fixing means 7 Heat exhaust means (exhaust fan)
8 Heat shield member 11 Transfer means (transfer belt)
13 Thermal insulation member 15 Image forming apparatus 18 Exterior member (left side plate)
18a Vent 19 Exterior member (right side plate)
19a Vent 21 Guide member

Japanese Patent No. 4009220 Japanese Patent No. 3503919

Claims (5)

A photoconductor, a charging unit for charging the photoconductor, a light writing unit for forming an electrostatic latent image on the photoconductor, and a developing unit for developing the electrostatic latent image to form a toner image; In an image forming apparatus comprising: a transfer unit that transfers a toner image on the photosensitive member to a transfer material; and a fixing unit that fixes the toner image transferred onto the transfer material by heat.
The optical writing means is disposed above the fixing means and has heat exhausting means for exhausting radiant heat generated from the fixing means to the outside of the apparatus, and between the optical writing means and the exhaust heat means, An image forming apparatus, wherein a heat shield member for preventing radiant heat from reaching the optical writing means is provided over the entire width of the apparatus. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the heat shield member is formed of a hollow metal member. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the heat shield member is formed of a non-metallic heat-resistant member. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus, wherein the heat shield member extends to an exterior member of the apparatus, and the exterior member is provided with a vent hole that can take in and discharge outside air. The image forming apparatus according to any one of claims 1 to 4,
The image forming apparatus, wherein the heat shield member includes a heat insulating member.

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