JP4871807B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, a facsimile machine, and a multifunction machine having at least two of these functions.

  In image forming apparatuses such as copiers, printers, facsimiles, and multifunction machines having at least two of these functions, colorization has become widespread, and in particular, a tandem type having a plurality of image carriers has a high speed. It is becoming an excellent mainstream. Among such apparatuses, an apparatus is also known that uses a process cartridge in which at least one of an image carrier and an image forming apparatus is accommodated in a housing.

  Further, in such an apparatus, a two-component developing system composed of a toner and a carrier is widely used because a developing apparatus that visualizes an electrostatic latent image formed on an image carrier greatly affects image quality. In this two-component development system, the stirring member is rotated in order to reliably mix the developer. If the rotation speed of the stirring member is increased to increase the stirring force, the temperature in the developing device rises due to the friction of the developer, particularly when the developing device is continuously operated, and the image quality deteriorates due to developer deterioration. In some cases, problems such as locking due to toner adhesion in the developing device may occur.

JP 2006-72030 A

  Therefore, as described in Patent Document 1 and the like, it has been proposed to install a fan and cool the developing device with an air flow. However, recent image forming apparatuses are densely packed with each unit as the miniaturization is promoted, and therefore it is difficult to secure a flow path through which an air flow flows. In the image forming apparatus described in Patent Document 1, an air flow path is provided between the image forming unit and the optical writing unit.

  However, in the image forming apparatus in which the mounted image forming unit is shifted upward from the unit support plate or set away from the support plate because the image carrier is in contact with the intermediate transfer belt, Patent Document 1 In addition, even if the air flow path is provided between the unit support plate and the optical writing unit, there is a problem that the cooling effect is poor because the flow path is separated from the imaging unit.

  An object of the present invention is to provide an image forming apparatus capable of suppressing a temperature increase of a developing device and an image carrier even when downsizing is promoted.

  In order to achieve the above object, the present invention includes a writing unit for performing optical writing on an image carrier, and a plurality of process cartridges having the image carrier, and the process cartridges are supported by a device body. In the image forming apparatus supported detachably by the means, the support means is formed with a writing slit through which writing light passes from the writing unit, and when the process cartridge is mounted on the apparatus main body, A plate-shaped partition member formed with a gap between the bottom and a rail portion standing on the partition member for guiding the loading and unloading of the process cartridge, and between the writing unit and the partition member An air flow generating means for generating an air flow from one end side to the other end side of the apparatus main body, An opening is formed at a position facing the gap when the process cartridge is mounted in the cartridge portion, and the air flow path is configured to communicate with the gap under the process cartridge through the writing slit and the opening. An image forming apparatus characterized by this is proposed.

  The present invention is effective when the gap between the bottom of the process cartridge and the partition member is formed by shifting upward when the process cartridge is mounted at the normal position of the apparatus main body.

  Further, according to the present invention, the process cartridge includes at least the image carrier and a developing device that visualizes an electrostatic latent image formed on the image carrier as a toner image, and the developing device includes an image carrier. It is effective that a developing roller facing the body and an agitating member for agitating the developer supplied to the developing roller are provided, and the agitating member and the writing slit are shifted to the left and right with respect to the vertical direction.

Furthermore, the present invention is effective when a plurality of the openings are horizontally long holes having a width that is longer than the height and are formed in the rail portion.
Furthermore, the present invention is effective when the openings formed in the rail portions are formed so as to communicate in a substantially straight line along the blowing direction of the blowing means.

Furthermore, the present invention is effective when the region where the opening is formed in the axial direction of the image carrier is a region corresponding to substantially the entire width of the image carrier.
Furthermore, in the present invention, the process cartridge is equipped with a developing device that forms yellow, magenta, cyan, and black toner images, respectively, and each of yellow, magenta, cyan, and black in this order in the blowing direction of the blowing unit. It is effective that the process cartridges are arranged in parallel, and the opening is not formed in the rail portion for guiding the yellow process cartridge but in the rail portion for guiding the process cartridge after magenta.

  Furthermore, in the present invention, the surface of the image carrier is exposed at the top of the process cartridge, and the partition plate restricts the process cartridge attached to the image forming apparatus main body from moving upward. Is effective.

  Furthermore, the present invention is effective when the air flow generation means and the space between the writing unit and the partition member are connected by a molded duct.

Furthermore, the present invention is effective when the inner surface of the duct facing the airflow generating means is formed in an arc shape protruding upstream in the airflow direction.
Furthermore, the present invention is effective when the gap between the duct and the writing unit is closed with a foam material.

  Still further, according to the present invention, the writing unit has an upper cover provided with a convex shape for arranging a dustproof glass plate for laser, and the convex shape is arranged for each color upstream of the writing slit. And effective.

  Furthermore, the present invention is effective when the dust-proof glass plate for laser is disposed on the opposite surface of the convex shape of the upper cover with respect to the blowing direction.

  According to the present invention, even in an image forming apparatus having a process cartridge that is promoted to be downsized and shifted upward when mounted, the developing device and the image carrier are directly connected to the air flow path of the air flow generating means. Therefore, it is possible to prevent image quality from being deteriorated due to deterioration of the developer due to temperature rise in the developing device and locking due to toner fixation in the developing device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a vertical sectional view showing an example of an image forming apparatus for forming a full-color image. The image forming apparatus shown here includes first to thorough drum-shaped photoreceptors arranged in an image forming apparatus main body 1. A fourth image carrier 2Y, 2M, 2C, 2K, and an endless intermediate transfer belt 3 disposed in the image forming apparatus main body 1 are also included. The intermediate transfer belt 3 is wound around at least the support rollers 4 and 5 and rotated in the direction of arrow A.

  The intermediate transfer belt 3 is positioned above the image carriers 2Y to 2K, and the lower running side of the intermediate transfer belt 3 is in contact with the peripheral surface of the image carriers 2Y to 2K. The intermediate transfer belt 3 constitutes an example of a transfer material onto which toner images of different colors formed on the surface of each image carrier are transferred in a superimposed manner.

  The configuration in which a toner image is formed on each of the first to fourth image carriers 2Y, 2M, 2C, and 2K and the toner image is transferred to the intermediate transfer belt 3 is substantially different only in the color of the toner image. Since all of them are the same, only a configuration in which a toner image is formed on the first image carrier 2Y and the toner image is transferred to the intermediate transfer belt 3 will be described.

  In FIG. 2, the image carrier 2Y is rotationally driven in the clockwise direction. At this time, the image carrier 2Y is charged to a predetermined polarity by a charging device including a charging roller 6Y to which a charging voltage is applied. The charged image carrier 2Y is irradiated with a light-modulated laser beam L emitted from the optical writing device 7 shown in FIG. 1, whereby an electrostatic latent image is formed on the image carrier 2Y. This electrostatic latent image is visualized as a yellow toner image by the developing device 10Y. The developing device 10Y includes a developing roller 11Y disposed opposite to the image carrier 2Y, and stirring screws 12Y and 13Y that stir the developer supplied to the developing roller 11Y. The stirring screws 12Y and 13Y are opposite to each other. The developer is conveyed and stirred while circulating in the apparatus.

  A primary transfer roller 8Y is disposed on the opposite side to the image carrier 2Y across the intermediate transfer belt 3, and a transfer voltage is applied to the primary transfer roller 8Y, whereby the toner image on the image carrier 2Y is transferred to the transfer belt. 3 is primarily transferred onto 3. The transfer residual toner adhering to the image carrier 2Y after the toner image transfer is removed by the cleaning device 9Y. When the image carrier 2Y that has passed through the cleaning device 9Y passes through the charging roller 6Y, it is charged simultaneously with charge removal to prepare for the next image formation.

  In exactly the same manner as described above, a cyan toner image, a magenta toner image, and a black toner image are respectively formed on the second to fourth image carriers 2M, 2C, and 2K shown in FIG. Are sequentially superposed on the intermediate transfer belt 3 to which the yellow toner image has been transferred, and are primarily transferred to form a composite toner image on the intermediate transfer belt 3. The transfer residual toner on the image carriers 2M, 2C, and 2K after the toner image transfer is removed by the cleaning devices 9M, 9C, and 9K, as in the case of the first image carrier 2Y.

  On the other hand, as shown in FIG. 1, a paper feed cassette 15 containing a recording medium P made of, for example, transfer paper and a paper feed device 14 having a paper feed roller 16 are arranged in the lower part of the image forming apparatus main body 1. The uppermost recording medium P is sent out in the direction of the arrow by the rotation of the paper feed roller 16. The sent recording medium P is composed of a portion of the intermediate transfer belt 3 wound around the support roller 5 at a predetermined timing by a pair of registration rollers (not shown) and a secondary transfer roller 17 placed on the portion. Sent in between. At this time, a predetermined transfer voltage is applied to the secondary transfer roller 17, whereby the composite toner image on the intermediate transfer belt 3 is secondarily transferred to the recording medium P.

  The recording medium P onto which the composite toner image has been secondarily transferred is further conveyed upward and passes through the fixing device 18, and at this time, the toner image on the recording medium P is fixed by the action of heat and pressure. The recording medium P that has passed through the fixing device 18 is discharged by a paper discharge unit to a paper discharge unit 19 at the top of the image forming apparatus main body 1. Further, the transfer residual toner adhering to the intermediate transfer belt 3 after the toner image is transferred is removed by a belt cleaning device (not shown).

  By the way, the charging device including the charging roller 6Y, the developing device 10Y, and the cleaning device 9Y constitute an image forming device for forming a toner image on the image carrier 2Y, which is another image carrier 2M. , 2C, 2K, charging rollers 6M, 6C, 6K, developing devices 10M, 10C, 10K and cleaning devices 9M, 9C, 9K are also the same.

  Here, each image carrier 2Y to 2K on which a toner image is formed on the surface and at least one image forming device for forming the toner image on each image carrier are integrally assembled. Constructed as cartridges 20Y, 20M, 20C, and 20K, the image forming apparatus of this example has a plurality of such process cartridges, and transfers toner images of different colors respectively formed on the image carriers 2Y to 2K. The recording image is obtained by transferring to an intermediate transfer belt 3 which is an example of the material.

  In the image forming apparatus of this example, the image carrier 2Y is rotatably supported by the unit case 21Y, and the image carrier 2Y, the developing device 10Y, the cleaning device 9Y, and the charging roller 6Y are assembled together. ing. The same process cartridges 20M, 20C, and 20K are respectively configured by the other image carriers 2C, 2M, and 2K and the image forming apparatuses provided around the image carriers.

  As described above, instead of integrating the image carrier, the charging device, the developing device, and the cleaning device into the process cartridge 20, the process cartridge 20 is configured by the image carrier and at least a part of the image forming device. May be. For example, the process cartridge 20 may be configured by an image carrier and at least one of a charging device, a developing device, and a cleaning device, and the process cartridge 20 may or may not include the developing device.

  The process cartridge 20 configured as described above is supported by a partition member 21 as a support means, as shown in FIGS. The partition member 21 is formed of a flat plate material fixed to the apparatus main body so as to partition the optical writing device 7 and the process cartridge 20, and the laser beam L from the optical writing device 7 passes through the partition member 21. A writing slit 22 is formed, and a rail plate 23 is erected as a rail portion that guides loading / unloading of the process cartridge 20. The rail plate 23 guides both sides of the process cartridge 20 to be attached to and detached from the image forming apparatus main body, and its height is set to be considerably lower than the height of the process cartridge 20.

  Further, as shown in FIG. 4, the partition member 21 has a projecting member 24 for shifting the process cartridge 20 upward immediately before the process cartridge 20 is mounted at the regular position, that is, the process cartridge mounting direction. Is provided on the most downstream side. The means for shifting the process cartridge 20 upward is constituted by the projection member 24 and a projection 25 provided on the front side, that is, the most upstream side in the process cartridge mounting direction, on the bottom surface of the process cartridge 20.

  When the process cartridge 20 is attached to the image forming apparatus main body 1, for example, when the surface on which the operation unit (not shown) of the image forming apparatus is provided is the front, the partition member 21 is moved from the front to the back. It is installed by sliding. When mounting, first, the process cartridge 20 is aligned after the protruding portion 26 provided on the front side of the rail plate 23 is inserted into a groove (not shown) formed on both side surfaces of the process cartridge 20. It pushes in to the back with the partition member 21 supporting it. When the process cartridge 20 is pushed and slides and reaches the position just before the normal position, the process cartridge 20 rides on the protruding member 24, and at the same time, the protrusion 25 of the process cartridge 20 also rides on the surface of the partition member 21 and reaches the normal position. As a result, the process cartridge 20 is shifted upward by the height of the projecting members 24, 25, and the image carrier 2 is mounted at a regular position in contact with the intermediate transfer belt 3. Therefore, the bottom surface of the process cartridge 20 is separated from the partition member 21, and a gap 27 is formed between the process cartridge 20 and the partition member 21. The overhanging portion 26 is loosely fitted in a groove (not shown) to function as a blocking portion that prevents the process cartridge 20 from being displaced upward during sliding and preventing the image carrier from hitting the frame or the like. is doing.

  It should be noted that the image forming apparatus according to the present embodiment only needs to have a gap 27 between the partition members 21 when the process cartridge 20 is mounted at a regular position. In addition to those that shift upward in accordance with the mounting operation as described above, any gap may be used as long as the gap 27 can be formed between the partition members 21 at a normal position such as lifting up by a lift or the like when mounted to a predetermined position.

  In the image forming apparatus according to the present embodiment, an intake fan 30 serving as an airflow generating unit that generates an airflow flowing between the writing unit 7 and the partition member 21 from the left end side to the right end side of the apparatus main body in FIG. 31 is provided. As shown in FIG. 3, the intake fans 30 and 31 are located on the left and right sides of the main body 1 as viewed from the left side. The airflow generated by the intake fans 30 and 31 is configured to flow between the writing unit 7 and the partition member 21 via the rectifying ducts 32 and 33.

  Thus, the airflow generated by the intake fans 30 and 31 flows between the writing unit 7 and the partition member 21, but if the air flows out of the apparatus as it is, the process cartridge 20 is shifted upward and between the partition member 21 as described above. Since the gap 27 is formed, the stirring members 12 and 13 of the developing device 10 cannot be efficiently cooled by the airflow.

  Therefore, in the present embodiment, an opening 28 made of a laterally long hole (track-shaped hole) whose lateral width is longer than a number of heights is provided at a height position facing the gap 27 of the rail plate 23. Further, as shown in FIG. 3, an exhaust port 41 communicating with the gap 27 is formed in the rear side plate 40 that supports the partition member 21.

  With this configuration, as shown in FIG. 5, the airflow from the intake fans 30 and 31 enters the gap 27 from the writing slit 22, and part of the airflow passes through the opening 28 into the gap of the adjacent process cartridge 20. As shown in FIG. 6, a part of the air passes through a duct (not shown) provided on the back surface of the rear side plate 40 and is discharged outside the apparatus through the exhaust fan 42. Even if the ozone filter may contain high-concentration ozone in this duct, the discharge of ozone to the outside of the machine can be suppressed.

  The opening 28 is not provided in the left rail plate 2 of the yellow process cartridge 20Y, as shown in FIG. Further, the exhaust port 41 communicating with the gap 27Y of the yellow process cartridge 20Y is not provided. This is because the yellow process cartridge 20 is closer to the intake fans 30 and 31 than the other process cartridges 20M, 20C, and 20K, and a sufficient cooling effect can be obtained even by indirect cooling via the non-direct gap 27. As another process cartridge, FIG. 8 shows a magenta process cartridge 20M. The magenta process cartridge 20M is provided with openings 28 in the rail plate 23, respectively.

  Thus, in the image forming apparatus of this embodiment, even if the process cartridge 20 is shifted upward, the gap 27 formed by the shift becomes a flow path of the air flow, so that the stirring screws 12 and 13 of the developing device 10 are directly connected. Even if the stirring force is increased by increasing the rotational speed of the stirring screws 12 and 13, the temperature rise in the developing device 10 can be suppressed. Further, the stirring screws 12 and 13 and the writing slit 22 are shifted to the left and right with respect to the vertical direction. As shown in FIG. 5, the air flows from the writing slit 22 onto the partition member 21 and then goes to the process cartridge 20 on the right side through the opening 28 of the rail plate 23. The air flowing from the left side of the opening 28 escapes to the right side, and the stirring screws 12 and 13 having high heat can be efficiently cooled. This is the same even when the air flows in the opposite direction.

  By the way, as shown in FIG. 4, the opening 28 formed in the rail plate 23 is formed in a track-like hole whose lateral width is longer than the height, so that pressure loss when air passes through the opening 28 is suppressed, and air permeability is achieved. Can be enhanced. Further, by forming a large number of openings 28 in the rail plate 23, the opening area can be increased while maintaining the strength of the rail plate 23.

  Further, as shown in FIG. 7, the opening 28 formed in each rail plate 23 is formed so as to be communicated substantially linearly along the airflow direction of the intake fans 30 and 31, thereby suppressing the turbulence of the airflow. It is configured to easily reach the process cartridge 20K. Note that the region in the width direction in which the opening 28 is formed is a region corresponding to substantially the entire width of the image carrier 2 so that the entire width can be uniformly cooled.

  Incidentally, the wind from the intake fans 30 and 31 is configured to flow between the writing unit 7 and the partition member 21 through the rectifying ducts 32 and 33. If air leakage occurs, the cooling effect may be halved.

  Therefore, in another embodiment of the present invention shown in FIGS. 9 and 10, the rectifying ducts 32 and 33 from the intake fans 30 and 31 to the space between the writing unit 7 and the partition member 21 are connected by molding.

With such a configuration, the airtightness of the flow path can be improved, air leakage can be reduced, and a good cooling effect can be obtained.
Further, the rectifying ducts 32 and 33 are formed in an arc shape in which the inner surfaces of the ducts facing the intake fans 30 and 31 are gently projected upstream in the airflow direction. That is, the rectifying ducts 32 and 33 are formed with an R shape 34 such that the inner surfaces of the ducts facing the intake fans 30 and 31 are convex inward.

  With this configuration, even if the intake fans 30 and 31 are disposed in the vicinity of the writing unit 7 and the partition member 21, the air from the intake fans 30 and 31 is caused to flow in the rectifying ducts 32 and 33 by the R shape 34. It is possible to avoid hitting the inner surface at an angle close to a right angle, and to reduce pressure loss at the suction port. Moreover, the noise in the rectifying ducts 32 and 33 can be reduced by reducing the pressure loss.

  Moreover, since the rectifying ducts 32 and 33 and the writing unit 7 are separate members, a gap may be formed between them. At this time, as shown in FIG. 10, the gap is closed with a foam material 35 such as sponge. With this configuration, air leakage between the rectifying ducts 32 and 33 and the writing unit 7 can be prevented, and vibrations of the intake fans 30 and 31 are transmitted to the writing unit 7 and an abnormal image is generated. Can be prevented.

  As shown in FIGS. 11 and 12, the writing unit 7 has an upper cover 70 provided with a convex shape 72 for arranging a dustproof glass plate 71 for laser. Since the convex shape 72 is arranged in each color upstream of the writing slit 22, the wind from the intake fans 30 and 31 is applied to the convex shape 72 of the upper cover 70 as shown in FIG. Therefore, the cooling efficiency toward the process cartridge 20 can be increased.

  Further, since the dust-proof glass plate 71 for laser is disposed on the surface opposite to the blowing direction in the convex shape 72 of the upper cover 70, dust and the like are conveyed to the upper portion of the writing unit 7 through the intake fans 30 and 31. Even if they are stuck, they can be prevented from adhering to the dust-proof glass plate 71 for laser.

1 is a schematic explanatory diagram illustrating an overall configuration of a color image forming apparatus of the present invention. It is explanatory drawing which shows the detail of a yellow process cartridge. It is a perspective view which shows the support means of a process cartridge. It is explanatory drawing which shows the process cartridge arrange | positioned in the regular position. FIG. 2 is a schematic explanatory diagram illustrating an air flow in the overall configuration of the image forming apparatus. It is a perspective view which shows the back side of a rear side board. It is plane explanatory drawing which shows the flow of the airflow of this invention. It is an explanatory view showing details of a magenta process cartridge. It is a perspective view which shows the intake fan with a rectification | straightening duct. It is explanatory drawing which shows the flow of the wind of an intake fan vicinity. It is a perspective view which shows the external appearance of a writing unit. It is explanatory drawing which shows the flow of the wind on a writing unit.

Explanation of symbols

2Y, 2M, 2C, 2K Image carrier 3 Intermediate transfer belt 7 Writing unit 10 Developing device 20Y, 20M, 20C, 20K Process cartridge 21 Partition member 22 Writing slit 23 Rail plate 27 Gap 28 Opening 30, 31 Intake fan 32, 33 Rectifying duct

Claims (13)

A writing unit for performing optical writing on the image carrier,
A plurality of process cartridges having the image carrier;
In the image forming apparatus, the process cartridge is detachably supported by a support means fixed to the apparatus body.
The support means has a flat plate shape in which a writing slit through which writing light passes from the writing unit is formed and a gap is formed between the process cartridge and the bottom of the process cartridge when the process cartridge is mounted on the apparatus main body. A partition member, and a rail portion standing on the partition member for guiding the loading and unloading of the process cartridge,
An airflow generating means for generating an airflow between the writing unit and the partition member from one end side to the other end side of the apparatus body is provided.
The rail portion of the support means has an opening formed at a position facing the gap when the process cartridge is mounted.
An image forming apparatus comprising: a flow path for the airflow in which a gap under a process cartridge communicates with the writing slit and the opening.   2. The image forming apparatus according to claim 1, wherein the gap between the bottom of the process cartridge and the partition member is formed by shifting upward when the process cartridge is mounted at a normal position of the apparatus main body. An image forming apparatus.   3. The image forming apparatus according to claim 1, wherein the process cartridge includes at least the image carrier and a developing device that visualizes the electrostatic latent image formed on the image carrier as a toner image. The developing device includes a developing roller facing the image carrier and an agitating member for agitating the developer supplied to the developing roller, and the agitating member and the writing slit are shifted to the left and right with respect to the vertical direction. An image forming apparatus.   2. The image forming apparatus according to claim 1, wherein a plurality of the openings are horizontally long holes having a lateral width longer than a height, and the plurality of openings are formed in the rail portion.   5. The image forming apparatus according to claim 4, wherein the opening formed in each rail portion is formed so as to communicate in a substantially straight line along the air flow direction of the air flow generating means. apparatus.   5. The image forming apparatus according to claim 4, wherein the region in which the opening is formed in the axial direction of the image carrier is a region corresponding to substantially the entire width of the image carrier. .   3. The image forming apparatus according to claim 1, wherein each of the process cartridges includes a developing device that forms yellow, magenta, cyan, and black toner images, and yellow, magenta, The process cartridges are arranged in parallel in the order of cyan and black, and at this time, the opening is not formed in the rail portion that guides the yellow process cartridge but in the rail portion that guides the process cartridge after magenta. An image forming apparatus.   3. The image forming apparatus according to claim 1, wherein a surface of an image carrier is exposed at an upper portion of the process cartridge, and a process cartridge attached to the main body of the image forming apparatus moves upward on the rail portion. An image forming apparatus comprising a blocking unit for restricting this.   2. The image forming apparatus according to claim 1, wherein the airflow generation unit and the writing unit and the partition member are connected by a molded duct. 3.   10. The image forming apparatus according to claim 9, wherein an inner surface of the duct facing the air flow generation unit is formed in an arc shape protruding upstream in the air flow direction.   The image forming apparatus according to claim 9, wherein a gap between the duct and the writing unit is closed with a foam material.   2. The image forming apparatus according to claim 1, wherein the writing unit has an upper cover provided with a convex shape for arranging a dust-proof glass plate for laser, and the convex shape is arranged on the upstream side of the writing slit for each color. An image forming apparatus that is arranged.   13. The image forming apparatus according to claim 12, wherein the dust-proof glass plate for laser is disposed on a convex surface of the upper cover on a surface opposite to a blowing direction.

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