JP5365493B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a support configuration capable of supporting an image writing unit, and of securing a cooling air ventilation path, without increasing the size of the apparatus, even if the scale of the image writing unit is increased. <P>SOLUTION: The image forming apparatus includes a front-positioning member configured to support both ends of the writing surface on a side where images of the image writing units are written; and a rear-support member disposed to face the center part of the rear surface opposite to the writing surface of the image writing unit to support the center part of the rear surface. Gaps are formed on both sides of the rear support member, located under the bottom surface of the image writing unit so that the ventilation paths for the cooling air which is blown from the rear surface toward the writing surface of the image writing unit, to cool the inside of the device, and the image writing unit is formed. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer. More specifically, the present invention includes an image writing unit and a developing device, and has an image writing unit supporting structure capable of securing a cooling air flow path. The present invention relates to a forming apparatus.

  In an electrophotographic image forming apparatus, a heating element such as a heating lamp or a drive motor or a movable member with frictional heat is used in the image forming process, and the temperature rise in the apparatus due to the heating element or the like is added to the image forming process. In order to adversely affect the image forming apparatus, a cooling unit (mainly a blowing unit) is arranged.

  An image fixing unit (fixing device) having a built-in heating lamp is heated to the highest temperature, and the developer (hereinafter referred to as toner) is melted to fix the toner image at a high speed of about 200 ° C. Until heated. However, the image fixing unit is often placed near a temperature-dependent photoconductor or transfer body, and it is necessary to prevent the ambient temperature of the photoconductor or transfer body from being affected. A method of forcibly cooling the image fixing unit and its surrounding space with a large fan is employed.

  In many cases, the developing unit (developing apparatus) uses a triboelectric charging method using a two-component developer containing toner and carrier. In this triboelectric charging device, frictional heat is generated in the stirring portion of the two-component developer and in the minute gap portion formed in the portion where the two-component developer is supplied to the developing roller to form a thin layer on the roller surface. The frictional heat is stored in the developing sleeve, the blade and the like. Furthermore, although heat is also stored in the two-component developer itself, this also circulates in the developing device and thus also serves as a coolant. As a result, due to the heat capacity of the developer itself and the heat dissipation effect to the surrounding space by the coolant, this frictional heat is lower than the melting temperature of the toner, and it has rarely caused major problems in the image forming process. There was little need for proper cooling.

  However, in recent years, when the development speed is increased due to a demand for high-speed image output and the use of low-temperature toner, the temperature rise due to frictional heat increases, and the melting temperature may be exceeded depending on the environmental conditions. In particular, when the allowable range of heat generation is limited by the use of low-temperature toner, more aggressive cooling is required.

  As the image writing unit (image writing unit), a mechanical scanning method using laser light is most widely used, and among them, an optical scanning method using a polyhedral reflecting mirror (polygon mirror) is practically adopted. The polygon mirror is rotated at a high speed by a drive motor (hereinafter referred to as a polygon motor), and the laser beam is scanned at a high speed, so the load on the polygon motor increases and the temperature rises.

  In particular, in a color image forming apparatus, a photoconductor and an image writing unit are arranged for each color. Therefore, if a temperature difference occurs in each exposure path due to the operation rate of the polygon motor, the exposure position is displaced, and as a result, The color reproduction performance changes due to the displacement of the individual colors. Therefore, the image writing unit needs to be limited to a certain temperature range, and means such as cooling the polygon motor that is a heat source intensively, for example, use the intake outside air only for forced cooling of multiple polygon motors. In addition, means such as exhausting the apparatus as it is is adopted.

  The cooling includes an image writing unit that forms a latent image on a carrier according to image data, and a developing device that uses the latent image as a developer image, and cools from the periphery of the image writing unit toward the developing device. An image forming apparatus configured to send out wind has been proposed (see, for example, Patent Document 1).

JP 2006-343607 A

  Japanese Patent Application Laid-Open No. 2004-228561 is configured to send cooling air in order of a low heating element among various functional units constituting the image forming apparatus so as to increase the efficiency of cooling in the apparatus.

  FIG. 1 is a schematic front view illustrating an example of a main configuration of an image forming unit 40 in the image forming apparatus. FIG. 2 is a right side view seen from the direction of arrow Xa in FIG.

  This image forming apparatus is called a tandem type color image forming apparatus, and is an endless intermediate transfer belt 7 stretched around a plurality of rollers and rotatably supported. The four image forming units 10 (10Y, 10M, 10C, and 10K) that form yellow, magenta, cyan, and black toner images are arranged in a column (hereinafter also referred to as a column arrangement).

  Each of the image forming units 10Y, 10M, 10C, and 10K includes a photosensitive drum 1 (1Y, 1M, 1C, and 1K) as a carrier on which a latent image is formed on the surface. The photosensitive drums 1Y, 1M, 1C, and 1K rotate in contact with the intermediate transfer body 7.

  The image writing units 41 (41Y, 41M, 41C, 41K) are arranged in a column at positions facing the peripheral surfaces of the photoreceptors 1Y, 1M, 1C, 1K.

  Hereinafter, the peripheral portions of the image forming unit 10Y and the image writing unit 41Y will be described as an example.

  In FIG. 1, the surface of the image writing unit 41Y that faces the photosensitive drum 1Y is a surface that emits laser light, that is, the writing surface 41A, and the opposite side is the rear surface 41B.

  Conventionally, the image writing unit 41 is supported by support members (stays) 110 and 120 that are provided in advance from the front side to the back side of the image forming apparatus main body. For example. Both ends on the writing surface 41A side are positioned and supported by a front positioning member (not shown) provided on the stay 110, and one point or two points on the rear surface 41B side are supported and fixed or placed on the stay 120. In the example shown in FIG. 1, the bottom plate is used as a substitute for the stay 120 on the rear surface 41B side of the image writing unit 41K.

  The cooling air is indicated by the arrows in FIG. 1 as the air flow path between the image writing units 41 arranged in cascade by sucking outside air by a blowing means (not shown) as described in Patent Document 1. To be blown. When this ventilation channel is viewed from the rear surface 41B side of the image writing unit 41, the hatched portion in FIG. 2 is the ventilation channel.

  However, in recent years, there has been a demand for downsizing of the image forming apparatus and an increase in size of the image writing unit 41 due to higher image quality.

  FIG. 3 is a diagram showing an example in which the image writing unit 41 is enlarged. 4 is a right side view seen from the direction of arrow Xa in FIG. In order to avoid an increase in the size of the apparatus, the interval between the photosensitive drums 1 is not changed.

  As shown in FIGS. 3 and 4, the gap between the image writing units 41 is narrowed. For this reason, in the method using the conventional stay 120, the narrow gap is closed, and it is difficult to form an appropriate ventilation channel for blowing the outside air sucked into the gap between the image writing units 41. Became. This particularly affected the cooling of the image writing unit 41, particularly the polygon motor that drives the polygon mirror.

  The present invention has been made in view of the above circumstances, and can support the writing unit without enlarging the apparatus even when the image writing unit is enlarged, and can secure a ventilation passage for cooling air. An object of the present invention is to provide an image forming apparatus having the configuration.

  The above object is achieved by the following configuration.

1. In an image forming apparatus comprising an image carrier and an image writing unit for writing an image on the image carrier based on image data and a developing device for forming a toner image,
A front positioning member that supports both ends of a writing surface on the image writing side of the image writing unit;
A rear support member disposed opposite to the central portion of the rear surface opposite to the writing surface of the image writing unit and supporting the central portion of the rear surface; An image is characterized in that a gap is formed on both sides of the support member so as to form a ventilation passage for cooling air that is blown in the direction from the rear surface to the writing surface to cool the inside of the apparatus and the image writing unit. Forming equipment.

  2. A plurality of the image carriers arranged in alignment, a plurality of the developing devices arranged close to each of the image carriers, and a plurality of the image writing units arranged for each of the image carriers. 2. The image forming apparatus according to 1, wherein the ventilation channel is formed in a gap between the image writing units.

  3. A plurality of the image writing units arranged in a line; and a single stay disposed at a position opposite to a central portion of the rear surface of the plurality of image writing units, wherein the rear support members that respectively support the plurality of image writing units are the stays. 3. The image forming apparatus according to 2 above, wherein the image forming apparatus is attached to an image forming apparatus.

  4). A rear plate member disposed across the plurality of image writing units at a position facing substantially the entire rear surface of the plurality of image writing units arranged in an array, and the rear plate member includes the ventilation flow 3. The image forming apparatus according to 2 above, wherein an opening is provided in a surface corresponding to a path, and the rear support member is attached to the rear plate member.

  5. 5. The image forming apparatus according to any one of claims 1 to 4, wherein a gap serving as a ventilation channel is provided between the rear surface and the stay or the rear plate member.

  As described above, even if the image writing unit is enlarged and the gap between the image writing units is narrowed, the support member can be prevented from blocking the entire gap between the image writing units, and the gap between the image writing units can be prevented. A ventilation channel for cooling air can be formed.

It is a schematic diagram of the front which shows the example of the main structures of an image formation part. It is the right view seen from the arrow Xa direction of FIG. It is a figure which shows the example which enlarged the image writing unit. It is the right view seen from the arrow Xa direction of FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention. It is a figure which shows an example of a structure of exposure apparatus. It is a schematic diagram of the front which shows the support structure of the image writing unit of this invention. It is the right view seen from the arrow Xa direction of FIG. It is a figure which shows another form of the support structure of a rear surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following.

  FIG. 5 is a schematic view showing an example of an image forming apparatus according to the present invention.

  An image forming apparatus 100 according to the present invention is referred to as a tandem color image forming apparatus, and includes an original conveying unit 20, an image reading unit 30, an image processing unit (not shown), an image forming unit 40, a paper feeding unit 50, a fixing unit. A device 60 and a paper discharge unit 70 are provided.

  The image forming unit 40 includes an endless intermediate transfer belt 7 that is stretched by a plurality of rollers 11, 12, 13, and 14 and is rotatably supported. Along the outer peripheral surface of the intermediate transfer belt 7, , Four image forming units 10Y, 10M, 10C, and 10K for forming yellow, magenta, cyan, and black toner images are arranged in tandem.

  The image forming units 10Y, 10M, 10C, and 10K have photosensitive drums 1Y, 1M, 1C, and 1K as image carriers on which latent images are formed on the surfaces. The photosensitive drums 1Y, 1M, 1C, and 1K rotate in contact with the intermediate transfer belt 7.

  Each of the photosensitive drums 1Y, 1M, 1C, and 1K includes charging devices 2Y, 2M, 2C, and 2K that charge the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K almost uniformly. Exposure devices 3Y, 3M, 3C, and 3K for writing an electrostatic latent image on the surface; developing devices 4Y and 4M that transfer toner to each latent image formed on the surface of each photosensitive drum to form a toner image; 4C and 4K, primary transfer devices 5Y, 5M, 5C, and 5K that transfer the toner images on the surface of the respective photosensitive drums onto the intermediate transfer member 7, and cleaning devices 6Y, 6M, and 6C that clean the surface of the photosensitive member after the transfer. , 6K are arranged in the order of operation along the outer peripheral surface.

  The developing devices 4Y, 4M, 4C, and 4K constituting the developing unit are arranged close to the photosensitive drums 1Y, 1M, 1C, and 1K and arranged in tandem in the rotation direction of the intermediate transfer body 7.

  The exposure devices 3Y, 3M, 3C, and 3K constituting the image writing unit 41 (see FIG. 1) are arranged in a column at positions facing the peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K. Here, the image writing unit 41 includes exposure devices 3Y, 3M, 3C, and 3K, and includes members required for positioning and fixing when the image forming apparatus 100 is mounted, and is detachable from the image forming apparatus 100. Say something.

  The document conveying unit 20 and the image reading unit 30 are mounted on the upper part of the main body of the image forming apparatus 100. Documents placed on the document table 21 of the document conveyance unit 20 with the writing surface facing upward are fed one by one by the pickup roller 22 and fed into the document conveyance path by the conveyance roller 23. When the original passes through the slit glass 25 disposed on the upper surface of the image reading unit 30 along with the rotation of the paper feed roller 24, an image is read by the optical system of the image reading unit 30.

  The image reading unit 30 includes a scanning unit A composed of a light source L for illuminating a document and a mirror 31, a traveling body B composed of two roof mirrors 32 and 33 for guiding reflected light, an imaging lens 34, and a CCD image sensor 35 (hereinafter referred to as the image sensor). And CCD sensor 35). In the image reading unit 30, when the original passes over the slit glass 25, the original is read by the scanning unit A stopped under the slit glass 25, and the reflected light has two roof mirrors 32 and 33. The traveling body B and the imaging lens 34 guide the CCD sensor 35 to form an optical image.

  The optical image read by the CCD sensor 35 is sent to an image processing unit (not shown). The image processing unit performs analog processing, A / D conversion, shading correction, color correction, halftone processing, and the like on the electronic image data, and then digitizes the image data of each color into each image forming unit 10Y, 10M, 10C. 10K exposure devices 3Y, 3M, 3C, and 3K are conveyed.

  FIG. 6 shows an example of the configuration of the exposure apparatus. The exposure devices 3Y, 3M, 3C, and 3K are housed in a flat box, and horizontally and hierarchically positioned at positions facing the photosensitive drums 1Y, 1M, 1C, and 1K with the developing devices 4Y, 4M, 4C, and 4K interposed therebetween. Are arranged. As a result, a gap is formed between the exposure apparatuses, and a cooling air flow path is formed. Since all the exposure apparatuses 3Y, 3M, 3C, and 3K have the same configuration, FIG. 6 shows the exposure apparatus 3Y, and the description and reference numerals for the other exposure apparatuses 3M, 3C, and 3K are omitted.

  In the exposure apparatuses 3Y, 3M, 3C, and 3K, the laser light is electrically modulated by the semiconductor laser oscillators 80Y, 80M, 80C, and 80K based on the image data separated into the respective colors, and the collimator lenses 81Y, 81M, 81C, and 81K. After being corrected to parallel light through the photosensitive drum 1Y by a correction optical system such as polygon mirrors 82Y, 82M, 82C, and 82K rotated at high speed by polygon motors 8Y, 8M, 8C, and 8K and fθ lenses 83Y, 83M, 83C, and 83K. Main scanning is performed in the rotation axis direction on 1M, 1C, and 1K. Further, sub-scanning is performed by rotating the photosensitive drums 1Y, 1M, 1C, and 1K, and the electrostatic latent images are reproduced on the peripheral surfaces of the photosensitive members 1Y, 1M, 1C, and 1K.

  Prior to exposure, predetermined surface charges are applied to the photosensitive drums 1Y, 1M, 1C, and 1K by corona discharge of the charging devices 2Y, 2M, 2C, and 2K. The charge of the exposed portion is reduced according to the exposure amount, and electrostatic latent images corresponding to the image data are formed on the respective photosensitive drums 1Y, 1M, 1C, and 1K by the potential difference of the electrostatic potential.

  The electrostatic latent image is visualized with toner of each color developer supplied from the developing devices 4Y, 4M, 4C, and 4K to become a toner image. The toner images of the respective colors formed on the photoreceptors 1Y, 1M, 1C, and 1K are sequentially transferred to the same position on the intermediate transfer body 7 that is rotated by the primary transfer devices 5Y, 5M, 5C, and 5K. A color image is formed by the synthesized toner on the body 7.

  On the other hand, a movable plate 52 that is lifted upward by lifting means is disposed at the bottom of the plurality of paper trays 51 that accommodate the recording paper P. The movable plate 52 on which the recording paper P is placed lifts the recording paper P to the upper limit position limited by the upper limit detection sensor in response to the paper feed start signal. At the same time, the pickup roller 53 falls so that the uppermost one of the loaded recording sheets P comes into contact with the pickup roller 53.

  The recording paper P in contact with the pickup roller 53 is taken out of the paper tray 51 by the contact pressure, separated one by one by the separation roller 54, and fed to the paper feed path. The fed recording paper P is guided to a plurality of intermediate rollers 55 arranged in the paper feed path and conveyed to the registration roller 56. The conveyed recording paper P is corrected for skew feeding of the recording paper P by the registration roller 56, and is fed to the secondary transfer section at a paper feed timing.

  The secondary transfer portion is composed of a secondary transfer roller 15 and a roller 13 (a roller that stretches the intermediate transfer belt 7) arranged to oppose the secondary transfer roller 15, and an electric field is generated from the secondary transfer roller 15 side to the roller 13 side. As a result, the unfixed color image of the synthesized toner on the intermediate transfer belt 7 is transferred onto the recording paper P at once. The recording paper P onto which the unfixed color image has been transferred is separated from the intermediate transfer belt 7 using paper stiffness or the like, and is conveyed to the fixing device 60 that is an image fixing unit while being guided by the conveyance guide plate.

  The fixing device 60 is disposed at a position opposite to the photoconductors 1Y, 1M, 1C, and 1K arranged in tandem with the intermediate transfer belt 7 interposed therebetween, near the secondary transfer portion along the side surface of the intermediate transfer body 7. Has been. Inside the fixing device 60, a heating roller 61 that melts the toner and a pressure roller 62 that presses the melted toner against the recording paper P are arranged in pressure contact with each other, and the recording paper P is sandwiched between the press contact portions and heated. Perform crimping. After the toner is fixed, the recording paper P heated for melting the toner is sandwiched between paper discharge rollers forming the paper discharge unit 70 and placed on a paper discharge tray outside the apparatus.

  The image forming apparatus 100 configured as described above is cooled because there is a portion that generates heat as described above. In the example shown in FIG. 5, a blower fan 410 is disposed as a blower unit in the casing of the image forming apparatus 100, and outside air is sucked into the apparatus and blown into the apparatus to form cooling air.

  However, when the size of the image writing unit 41 is increased as described above, the conventional support method for the image writing unit 41 secures an appropriate flow path for cooling air in the gap between the image writing units 41. It was difficult to do.

  FIG. 7 is a schematic front view showing a support structure of the image writing unit 41 of the present invention. FIG. 8 is a right side view seen from the direction of the arrow Xa in FIG.

  As shown in the figure, in the present invention, the image writing units 41 (41Y, 41M, 41C, 41K) arranged in tandem correspond to each image writing unit 41 at a position facing the center of the rear surface 41B. One stay 151 is provided in the main body of the image forming apparatus 100 in advance.

  To the stay 151, a support member 152 for fixing or placing the central portion on the rear surface 41B side of the image writing unit 41 (41Y, 41M, 41C, 41K) is attached. The support member 152 is provided with a reference surface 152a for positioning the central portion on the rear surface 41B side of each image writing unit 41.

  The stay 151 is provided with a predetermined width centered on the central portion (see FIG. 8) of the rear surface 41B of the image writing unit 41. The predetermined width is set so as to minimize the gap between the image writing units 41 and to satisfy the strength capable of supporting the rear surface 41B of each image writing unit 41. Further, when the stay 151 also serves as a strength member of a casing constituting the image forming apparatus 100, the setting is made in consideration of the necessary strength.

  With this configuration, even if the image writing unit 41 becomes larger and the gap between the image writing units 41 becomes narrower, the stay 151 can be prevented from blocking the entire gap between the image writing units 41. As shown by the hatched portion in FIG. 8, a cooling air flow path can be formed in the gap between the image writing units 41.

  Further, a gap serving as a cooling air flow path may be provided between the rear surface 41B and the stay 151, and a ventilation flow path may also be formed outside the rear surface 41B. In this case, it is possible to reduce the blowing loss of the outside air that has been taken in, and to increase the overall air volume.

  7 and 8, both ends of the image writing unit 41 on the writing surface 41 </ b> A side are positioned and supported by positioning pins 411 a that are front positioning members provided on the stay 110. The rear surface 41B side of the image writing unit 41 is positioned in the vertical direction by the reference surface 152a. Further, the image writing unit 41 is pressed in the direction of the stay 110 by a pressing member, for example, a pressing spring 153, on the rear surface 41B, so that the photosensitive drum 1Y (1M, 1C, 1K) direction (left and right direction in FIG. 7) Positioning is done.

  FIG. 9 is a view showing another form of the support structure of the rear surface 41B shown in FIGS. Instead of the stay 151, a rear plate member 161 is disposed over substantially the entire rear surface 41B of each image writing unit 41. This may be required from the configuration of the casing of the image forming apparatus 100 or the like. In this case, the support member 152 is attached to the rear plate member 161.

  By providing the vent hole 161 a in the portion of the rear plate member 161 that faces the gap between the image writing units 41, it is possible to prevent the entire gap between the image writing units 41 from being blocked. Further, a vent hole 171 may be provided in a part of the housing of the image forming apparatus 100 facing the side surface of the image writing unit 41.

  With this configuration, even if the image writing unit 41 is enlarged and the gap between the image writing units 41 is narrowed, the rear plate member 161 is prevented from closing the entire gap between the image writing units 41. In addition, it is possible to form a cooling air flow path in the gap between the image writing units 41.

1Y, 1M, 1C, 1K Photosensitive drum 2Y, 2M, 2C, 2K Charging device 3Y, 3M, 3C, 3K Exposure device 4Y, 4M, 4C, 4K Developing device 7 Intermediate transfer belt 8Y, 8M, 8C, 8K Polygon motor 20 Document conveying section 30 Image reading section 40 Image forming section 41 (41Y, 41M, 41C, 41K) Image writing section 50 Paper feeding section 51 Paper tray 60 Fixing device 80Y, 80M, 80C, 80K Semiconductor laser oscillators 82Y, 82M, 82C, 82K Polygon mirror 100 Color image forming apparatus 110, 120, 151 Stay 152 Support member 161 Rear plate member 161a Ventilation port 410 Blower fan P Recording paper

Claims (5)

In an image forming apparatus comprising an image carrier and an image writing unit for writing an image on the image carrier based on image data and a developing device for forming a toner image,
A front positioning member that supports both ends of a writing surface on the image writing side of the image writing unit;
A rear support member disposed opposite to the central portion of the rear surface opposite to the writing surface of the image writing unit and supporting the central portion of the rear surface; An image is characterized in that a gap is formed on both sides of the support member so as to form a ventilation passage for cooling air that is blown in the direction from the rear surface to the writing surface to cool the inside of the apparatus and the image writing unit. Forming equipment.   A plurality of the image carriers arranged in alignment, a plurality of the developing devices arranged close to each of the image carriers, and a plurality of the image writing units arranged for each of the image carriers. The image forming apparatus according to claim 1, wherein the ventilation channel is formed in a gap between the image writing units.   A plurality of the image writing units arranged in a line; and a single stay disposed at a position opposite to a central portion of the rear surface of the plurality of image writing units, wherein the rear support members that respectively support the plurality of image writing units are the stays. The image forming apparatus according to claim 2, wherein the image forming apparatus is attached to the image forming apparatus.   A rear plate member disposed across the plurality of image writing units at a position facing substantially the entire rear surface of the plurality of image writing units arranged in an array, and the rear plate member includes the ventilation flow The image forming apparatus according to claim 2, wherein an opening is provided in a surface corresponding to a path, and the rear support member is attached to the rear plate member.   The image forming apparatus according to claim 1, wherein a gap serving as a ventilation channel is provided between the rear surface and the stay or the rear plate member.

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