JP2006268064A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tandem image forming apparatus which allows a running cost to be reduced and is ecological. <P>SOLUTION: A developing unit 18 is made attachable to and detachable from a photoreceptor drum unit 19, and the developing unit 18 and the photoreceptor drum unit 19 are made attachable to and detachable from a main body casing 2 as one body, and the developing unit 18 is made attachable to and detachable from the photoreceptor drum unit 19 being attached to the main body casing 2. Therefore, only the developing unit 18 having a high frequency in replacement can be replaced. The developing unit 18 and the photoreceptor drum unit 19 can be stably installed as one body by having contact parts 39 and 48 thereof brought into contact with an installation face. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a color laser printer.

As an electrophotographic color laser printer, a so-called tandem type color laser printer in which a plurality of process units including a toner box, a developing roller, and a photosensitive drum are provided corresponding to toners of yellow, magenta, cyan, and black. It has been known.
In such a tandem color laser printer, in each process unit, each color toner contained in the toner box is supplied to the photosensitive drum by the developing roller, and each color toner image is formed on the photosensitive drum almost simultaneously. A color image can be formed at almost the same speed as a monochrome laser printer.

In such a tandem type color laser printer, for example, as described in JP-A-2002-72602 (Patent Document 1), a toner box, a developing roller, and a photosensitive drum are integrally provided in each process unit. In the case of toner empty, each process unit is replaced.
JP 2002-72602 A

However, if the process unit is replaced for each toner empty, the photosensitive drum is also replaced for each toner empty, so that the running cost increases and an increase in industrial waste occurs.
An object of the present invention is to provide a tandem image forming apparatus that can reduce running costs and is environmentally friendly.

  In order to achieve the above object, an invention according to claim 1 is an image forming apparatus, comprising: a developing portion having a developer containing chamber for containing a developer; and a developer carrying member for carrying the developer; An image carrier having an image carrier for carrying a developer image formed by developing an electrostatic latent image with a developer carried on the agent carrier for each of a plurality of colors, and the developing unit Is detachably attached to the image carrier, the developer is attached to the image carrier, and the developer and the image carrier are integrated into the image forming apparatus main body. Each of the developing unit and the image carrying unit is provided so that they can be placed together in a state where the developing unit and the image carrying unit are detached from the main body of the image forming apparatus. Equipped with a contact part that contacts the mounting surface It is characterized in that.

  According to such a configuration, since the developing unit can be attached to and detached from the image carrying unit, in toner empty, after the used developing unit is detached from the image carrying unit, a new one is attached to the image carrying unit. If the developing unit is attached, only the developing unit having a high replacement frequency can be replaced. As a result, it is possible to reduce running costs and industrial waste. On the other hand, when replacing the image bearing member, the developing unit and the image bearing unit are detached from the main body of the image forming apparatus, and the developing unit is detached from the used image bearing unit. If the developing unit is attached to the carrying unit and these are integrated into the image forming apparatus main body, the image carrying unit that is less frequently exchanged can be easily replaced. Further, in a state where the image forming apparatus is detached from the image forming apparatus main body, the developing unit and the image carrying unit can be stably and integrally placed by the respective contact units provided in the developing unit and the image carrying unit. For this reason, it is possible to prevent the developing unit and the image carrying unit from falling and to make them easy to handle.

According to a second aspect of the present invention, in the first aspect of the present invention, the developing unit and the image carrying unit are placed independently of each other by the contact portion.
According to such a configuration, the developing section and the image carrying section can be placed independently by the contact section. Therefore, it is possible to make the developing unit and the image carrying unit easier to handle.

According to a third aspect of the present invention, in the invention according to the first or second aspect, the image carrying portion includes a covering portion for covering a part of the developing portion, and the covering portion includes the covering portion. A contact portion is provided.
According to such a configuration, the covering portion covers a part of the developing portion, and the contact portion of the covering portion prevents both the developing portion and the image carrying portion or the image carrying portion alone from falling. can do. For this reason, it is possible to prevent both the developing unit and the image carrying unit or the image carrying unit alone from falling while reducing the number of parts.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the developing unit is detachably provided with respect to the image carrying unit mounted on the main body of the image forming apparatus. It is characterized by having.
According to such a configuration, the developing unit can be attached to and detached from the image carrying unit while the image carrying unit is mounted on the image forming apparatus main body. It is possible to replace only the developing unit without doing so. Therefore, it is possible to facilitate replacement of the developing unit.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the opposite side of the transfer position on the image carrier onto which the developer image carried on the image carrier is transferred. The image forming apparatus main body includes a first opening / closing member provided to be openable / closable, and the developing unit and the image carrying unit are attached to and detached from an opening formed by opening the first opening / closing member. It is characterized by being provided as follows.

According to such a configuration, since the developing unit and the image carrying unit are attached and detached on the opposite side of the transfer position, it is possible to avoid interference with the transfer unit that transfers the developer image. Therefore, it is possible to ensure attachment / detachment of the developing unit and the image carrying unit.
According to a sixth aspect of the present invention, in the invention according to any of the first to fifth aspects, an engaging portion provided in the image carrying portion and the developing portion engageable with the engaging portion. And an engaged portion provided on the head.

According to such a configuration, the developing portion can be attached to and detached from the image carrying portion by engaging / disengaging the engaging portion provided in the image carrying portion and the engaged portion provided in the developing portion.
The invention according to claim 7 is characterized in that, in the invention according to any one of claims 1 to 6, the image forming apparatus further comprises a grip portion provided in the developing portion for gripping the developing portion. Yes.

According to such a configuration, the developing unit alone or both the developing unit and the image carrying unit can be smoothly attached to and detached from the image forming apparatus main body by holding the holding unit. Therefore, operability can be improved.
According to an eighth aspect of the invention, in the seventh aspect of the invention, a space is provided above the gripping portion in a state where the developing portion is mounted on the image forming apparatus main body. It is a feature.

According to such a configuration, since the space is provided above the grip portion in a state where the developing portion is mounted on the image carrier portion, the grip portion can be easily gripped from the space. Therefore, it is possible to improve the operability during the attaching / detaching operation.
The invention according to claim 9 is the invention according to any one of claims 6 to 8, wherein the invention is provided in the developing portion for releasing the engagement between the engaging portion and the engaged portion. It is characterized by having an operation section.

According to such a configuration, engagement / disengagement between the engaging portion provided in the image carrying portion and the engaged portion provided in the developing portion can be operated in the operation portion of the developing portion. That is, the attaching / detaching operation of the developing unit with respect to the image carrying unit can be operated from the developing unit side. Therefore, the attachment / detachment work can be facilitated and the operability can be improved.
According to a tenth aspect of the present invention, in the invention according to any one of the first to ninth aspects, the developing is provided in the image carrier, and the developer carrier is opposed to the image carrier. And a guided portion provided in the developing unit and guided by the first guide unit.

According to such a configuration, the guided portion provided in the developing portion is guided by the first guide portion provided in the image carrying portion, so that the developer carrying member is guided so as to face the image carrying member. Therefore, the positional accuracy of the developer carrier with respect to the image carrier is good. As a result, it is possible to satisfactorily form a color image.
According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, the image forming apparatus main body includes a second guide portion that is provided on the main body of the image forming apparatus and guides the attachment / detachment of the developing unit with respect to the main body of the image forming apparatus. It is characterized by being.

According to such a configuration, the attaching / detaching operation of the developing unit with respect to the image forming apparatus main body can be ensured by the second guide portion provided in the image forming apparatus main body.
According to a twelfth aspect of the present invention, in the invention according to the eleventh aspect, the second guide portion includes the second portion of the image bearing portion in which the guided portion of the developing portion is mounted on the main body of the image forming apparatus. The guided portion of the developing unit is guided so as to be guided to a guidance start position of one guide unit.

According to such a configuration, the developing unit is guided to the guidance start position of the first guiding unit by the second guide unit, and then the first guiding unit guides the developer carrier to a position facing the image carrier. Is done. Thus, even when the image carrier is mounted on the image forming apparatus main body, the developer carrier can be arranged with high positional accuracy with respect to the image carrier.
According to a thirteenth aspect of the present invention, there is provided a third guide for guiding the attachment / detachment of the image carrier with respect to the main body of the image forming apparatus according to the eleventh or twelfth aspect of the invention. It is characterized by having a part.

According to such a configuration, it is possible to ensure the attaching / detaching operation of the image carrier with respect to the image forming apparatus main body by the third guide part provided in the image forming apparatus main body.
According to a fourteenth aspect of the present invention, in the invention according to the thirteenth aspect, an exposure unit for exposing the image carrier to form an electrostatic latent image corresponds to each of the image carriers. The second guide part and the third guide part are provided substantially parallel to the surface of the casing of the exposure means.

According to such a configuration, since the second guide portion and the third guide portion are provided substantially parallel to the surface of the casing of the exposure unit, the developing unit alone, or both the developing unit and the image carrying unit, It can be detached from between each exposure means.
The invention according to claim 15 is the invention according to claim 13 or 14, wherein the second guide part and the third guide part are provided on both sides in the axial direction of the developing part and the developer carrier. It is characterized by being provided to face each other.

According to such a configuration, since the second guide portion and the third guide portion are provided so as to face the developing portion on both sides in the axial direction of the developer carrier, the image forming apparatus main body can be configured with a simple configuration. It is possible to guide the attachment / detachment of the developing unit with respect to.
The invention according to claim 16 is the invention according to claim 15, wherein the developer accommodating chamber is provided with a plurality of developer conveying members provided at predetermined intervals in the attaching / detaching direction. The developing unit is associated with the second guide unit in the vicinity of a position corresponding to the developer carrier and a position corresponding to the developer transport member furthest from the developer carrier in the attaching / detaching direction. It is characterized by comprising engaging members.

  According to such a configuration, the developing unit is provided in the vicinity of the position corresponding to the developer carrier and the vicinity of the position corresponding to the developer transport member farthest from the developer carrier in the attaching / detaching direction. Is engaged with the second guide part, and the developing part can be guided in a state in which rattling in the attaching / detaching direction is prevented. Therefore, even if the developing unit is formed long in the attaching / detaching direction, stable attachment / detachment to / from the image forming main body can be achieved.

According to a seventeenth aspect of the present invention, in the invention according to any one of the first to sixteenth aspects, the exposure means for exposing the image carrier to form an electrostatic latent image includes the image carrier. The developing units and the exposure means are alternately arranged.
According to such a configuration, since each developing unit and each exposure unit are alternately arranged, the developing unit alone or both the developing unit and the image carrying unit can be detached from between each exposure unit. it can.

The invention according to claim 18 is characterized in that, in the invention according to claim 17, the developing sections and the exposure means are alternately arranged in a substantially vertical direction.
According to such a configuration, since the developing units and the exposure units are alternately arranged in the substantially vertical direction, the installation area can be saved.

  According to a nineteenth aspect of the present invention, in the eighteenth aspect of the present invention, there is provided a recording medium accommodating means for accommodating a recording medium onto which the developer image is transferred and being detachably provided to the image forming apparatus main body. And an operation panel for operating the image forming apparatus, and a recording medium discharge means for discharging the recording medium, the detaching direction of the recording medium storage means, the display direction of the operation panel, The discharge direction of the recording medium discharged from the recording medium discharge unit and the detaching direction of the developing unit and the image carrying unit are substantially the same direction.

According to such a configuration, the detaching direction of the recording medium accommodating means, the display direction of the operation panel, the discharging direction of the recording medium discharged from the recording medium discharging unit, and the detaching direction of the developing unit and the image carrying unit However, since the directions are substantially the same, the operator can access all of these operations from substantially the same direction. Therefore, operability can be improved.
The invention according to claim 20 is characterized in that, in the invention according to any one of claims 17 to 19, the casing surface of the exposure means also serves as a guide member for the image carrier. .

According to such a configuration, the housing surface of the exposure unit also serves as a guide member for the image carrier, so that the size of the apparatus can be reduced while reducing the number of parts and simplifying the apparatus configuration. it can.
The invention according to claim 21 is the invention according to any one of claims 1 to 20, wherein the developer image carried on the image carrier is transferred onto the image carrier after being transferred to a transfer medium. The remaining developer is collected by the developer carrier.

  According to such a configuration, after the developer image is recorded on the transfer medium, the developer remaining on the image carrier is collected by the developer carrier, so that the developer remaining on the image carrier is collected. Therefore, it is not necessary to provide a storage means for doing so, and the apparatus configuration can be simplified and the apparatus can be downsized. In addition, when such storage means is provided integrally with the image carrier, the life of the image carrier is determined by the capacity of the storage means, and either the longer life of the image carrier or the miniaturization of the apparatus can be achieved. However, in the configuration of the present invention, it is possible to achieve both.

The invention according to claim 22 is the invention according to any one of claims 1 to 21, wherein each of the image carrying portions includes a coating position that covers a transfer position to which the carried developer image is transferred. A shutter member is provided so as to be movable to an exposure position that exposes the transfer position, and an urging means that urges the shutter member to a covering position.
According to such a configuration, when the shutter member is moved by the urging means, the shutter member is moved to the covering position, and the transfer position is covered with respect to the image carrier. On the other hand, when the shutter member moves against the urging force of the urging means, the shutter member is moved to the exposure position, and the transfer position is exposed to the image carrier. Therefore, the selective movement of the shutter member to the covering position or the exposure position allows the image carrier to be exposed to the transfer position only when necessary, and prevents damage and deterioration of the image carrier. can do.

  According to a twenty-third aspect of the present invention, in the invention of the twenty-second aspect, the transfer means for transferring the developer image on the image carrier onto a transfer medium at the transfer position, and the transfer means are supported. A second opening / closing member provided in the image forming apparatus main body so as to be openable and closable; and when the second opening / closing member is in a closed state, when the shutter member is in an exposed position and the second opening / closing member is in an open state And a shutter moving means having the shutter member as a covering position.

  According to such a configuration, when the second opening / closing member is in the open state, the shutter member is moved to the covering position by the shutter moving means. Therefore, it is possible to prevent the image carrier from being exposed to the space formed by the open state of the second opening / closing member, and to prevent damage and deterioration of the image carrier. On the other hand, when the second opening / closing member is in the closed state, the shutter member is moved to the exposure position by the shutter moving means. Therefore, at the transfer position, the transfer operation can be performed with the image carrier facing the transfer means supported by the second opening / closing member.

  According to a twenty-fourth aspect of the present invention, there is provided a developer image formed by developing an electrostatic latent image with a developer, an image carrier provided for each color, and a transfer on the image carrier. On the opposite side of the position, a first opening / closing member provided to be openable / closable with respect to the image forming apparatus main body, transfer means for transferring a developer image on each image carrier to a transfer medium, and A shutter member movably provided to a coating position that covers a transfer position facing the transfer unit; an exposure position that exposes the transfer position; a biasing unit that biases the shutter member to the coating position; and the transfer And a second opening / closing member provided in the image forming apparatus main body so as to be openable / closable, and when the second opening / closing member is in a closed state, the shutter member is in an exposed position, and the second opening / closing member is in an open state. It is in And a shutter moving means having the shutter member as a covering position, and when the second opening / closing member is closed, the image carrier is mounted from an opening formed by opening the first opening / closing member. The shutter member is moved to the exposure position by the shutter moving means.

  According to such a configuration, when the second opening / closing member is in the open state, the shutter member is moved to the covering position by the shutter moving unit, and when the second opening / closing member is in the closed state, the shutter member is moved by the shutter moving unit. Is moved to the exposure position. Then, when the image carrier is mounted from the opening formed by opening the first opening / closing member in the closed state of the second opening / closing member, the shutter member is moved to the exposure position by the shutter member. Accordingly, it is possible to prevent the image carrier from being exposed to the space formed by the open state of the second opening / closing member, and to prevent damage and deterioration of the image carrier. In addition, at the transfer position, the transfer operation can be performed with the image carrier facing the transfer means supported by the second opening / closing member.

According to a twenty-fifth aspect of the present invention, in the twenty-fourth aspect of the present invention, the engaged portion provided in the shutter member and the second opening / closing member provided to be engageable with the engaged portion. And an engaging portion that moves in conjunction with the opening / closing operation.
According to such a configuration, the engaged portion provided on the shutter member is disengaged from the engaging portion that moves in conjunction with the opening / closing operation of the second opening / closing member, thereby moving the shutter member to the covering position or the exposure position. Can be moved. Therefore, the shutter member can be moved to the covering position or the exposure position in conjunction with the opening / closing operation of the second opening / closing member.

According to the first aspect of the present invention, it is possible to reduce running costs and industrial waste. In addition, it is possible to prevent the developing unit and the image carrying unit from falling and to handle them easily.
According to the second aspect of the present invention, the developing section and the image carrying section can be made easier to handle.

According to the third aspect of the present invention, it is possible to prevent both the developing unit and the image carrying unit or the image carrying unit alone from falling while reducing the number of parts.
According to the fourth aspect of the present invention, it is possible to facilitate replacement of the developing unit.
According to the fifth aspect of the present invention, it is possible to ensure attachment / detachment of the developing unit and the image carrying unit.

According to the sixth aspect of the present invention, the developing unit can be attached to and detached from the image bearing unit.
According to the invention described in claim 7, the operability can be improved.
According to the eighth aspect of the present invention, it is possible to improve the operability during the attaching / detaching operation.
According to the ninth aspect of the invention, the attachment / detachment work can be facilitated and the operability can be improved.

According to the tenth aspect of the present invention, the positional accuracy of the developer carrier relative to the image carrier is good. As a result, it is possible to satisfactorily form a color image.
According to the eleventh aspect of the invention, the attaching / detaching operation of the developing unit can be ensured.
According to the twelfth aspect of the present invention, even when the image carrier is mounted on the image forming apparatus main body, the developer carrier can be arranged with high positional accuracy with respect to the image carrier.

According to the invention of the thirteenth aspect, it is possible to ensure the attaching / detaching operation of the image carrier.
According to the fourteenth aspect of the present invention, the developing unit alone or both the developing unit and the image carrying unit can be attached and detached from between the exposure units.
According to the fifteenth aspect of the present invention, it is possible to guide the attachment / detachment of the developing unit with respect to the image forming apparatus main body with a simple configuration.

According to the sixteenth aspect of the present invention, even if the developing portion is formed long in the attaching / detaching direction, stable attachment / detachment to / from the image forming main body can be achieved.
According to the seventeenth aspect of the present invention, the developing unit alone or both the developing unit and the image carrying unit can be attached and detached from between the exposure units.
According to the invention described in claim 18, the installation area can be saved.

According to the nineteenth aspect, the operability can be improved.
According to the twentieth aspect of the invention, it is possible to reduce the size of the device while reducing the number of parts and simplifying the device configuration.
According to the twenty-first aspect of the present invention, it is possible to simplify the device configuration and reduce the size of the device.

According to the twenty-second aspect of the present invention, damage and deterioration of the image carrier can be prevented.
According to the invention of claim 23, when the second opening / closing member is in the open state, the image carrier is prevented from being exposed to the space formed by the open state, Deterioration can be prevented. On the other hand, when the second opening / closing member is in the closed state, the transfer operation can be performed with the image carrier facing the transfer means supported by the second opening / closing member at the transfer position.

According to the twenty-fourth aspect of the present invention, it is possible to prevent the image carrier from being exposed to the space formed by the open state of the second opening / closing member, and to prevent damage and deterioration of the image carrier. . In addition, at the transfer position, the transfer operation can be performed with the image carrier facing the transfer means supported by the second opening / closing member.
According to the invention of claim 25, the shutter member can be moved to the covering position or the exposure position in conjunction with the opening / closing operation of the second opening / closing member.

FIG. 1 is a cross-sectional side view of an essential part showing an embodiment of a color laser printer as an image forming apparatus of the present invention.
In FIG. 1, a color laser printer 1 includes a main body casing 2 as an image forming apparatus main body, a paper feeding unit 4 for feeding paper 3 as a transfer medium and a recording medium, and a fed paper 3. An image forming unit 5 for forming an image and a paper discharge unit 6 for discharging the paper 3 on which the image is formed are provided.

  The main casing 2 is formed in a substantially rectangular box shape, and its front side (hereinafter, the side on which the operation panel 60 in the substantially horizontal direction of the color laser printer 1 is provided is the front side, and the side on which the transfer unit 15 is provided is the rear side. ) Is provided with a front cover 7 as a first opening / closing member. The lower end of the front cover 7 is rotatably supported via a hinge 7a, and can be opened and closed with respect to the main casing 2 as indicated by a virtual line.

A rear cover 8 as a second opening / closing member is provided on the rear side. The rear cover 8 is rotatably supported at its lower end portion via a hinge 8a, and is moved integrally with a transfer portion 15 (to be described later) and can be opened and closed with respect to the main casing 2 as indicated by an imaginary line. It is said that.
Note that a discharge port 9 as a recording medium discharge unit for discharging the paper 3 and a discharge port for stacking the paper 3 discharged from the discharge port 9 are stacked on the upper part of the main casing 2. A concave paper discharge tray 10 with a deeper depression on the 9 side is provided.

An operation panel 60 for operating the color laser printer 1 is provided in the main body casing 2 below the front end of the paper discharge tray 10.
The paper feed unit 4 includes a paper feed tray 11 serving as a recording medium storage unit that is detachably attached to the main body casing 2 from the front side in a substantially horizontal direction at the bottom of the main body casing 2, and the paper feed tray 11 A paper feed roller 12 provided above one end (upper front) and a transport roller provided above the paper feed roller 12 and opposed to the upstream side in the transport direction with respect to the lowest yellow process section 14Y in the transport belt 56 described later. 13.

Sheets 3 are stacked in the sheet feed tray 11, and the uppermost sheet 3 is fed one by one toward the transport roller 13 in the substantially vertical direction by the rotation of the sheet feed roller 12. Then, the sheet is sequentially fed from the conveyance roller 13 to between the conveyance belt 56 and each photosensitive drum 44 (transfer position).
The image forming unit 5 includes a process unit 14, a transfer unit 15 as a transfer unit, and a fixing unit 16.

The process unit 14 is provided for each color. In other words, the process unit 14 includes four units, that is, a yellow process unit 14Y, a magenta process unit 14M, a cyan process unit 14C, and a black process unit 14K. These process units 14 are sequentially arranged in parallel in a substantially vertical direction at a predetermined interval from the lower side to the upper side.
Each process unit 14 includes a scanner unit 17 as an exposure unit, a development unit 18 as a development unit, and a photosensitive drum unit 19 as an image carrier.

  The scanner unit 17 is disposed at a predetermined interval from the conveyance belt 56 in a substantially horizontal direction, and is fixed to the main body casing 2 for each scanner unit 17. As shown in FIG. 2A, a scanner unit 17 includes a laser light emitting unit (not shown), a polygon mirror 21, two lenses 22 and 23, and three reflecting mirrors 24 in a scanner casing 20 as a housing. , 25 and 26.

  The scanner casing 20 is formed in a substantially elongated box shape, and a scanner side guide portion 28 for integrally guiding the photosensitive drum unit 19 when the photosensitive drum unit 19 is attached and detached is integrally formed on the upper wall thereof. The scanner-side guide portion 28 is provided on the upper wall so as to extend in the vicinity of the conveyance belt 56 from the middle of the scanner casing 20 in the substantially horizontal direction, and its front end portion gradually bulges upward toward the rear. It is formed as follows.

Further, as shown in FIG. 3, the scanner-side guide portion 28 has a cover portion 47 of a drum casing 43, which will be described later, in a substantially central portion in the width direction (a direction orthogonal to the front-rear direction in plan view, the same applies hereinafter). A guide groove 29 with which the boss 61 is slidably engaged is formed so as to extend in the front-rear direction and protrude upward in a substantially concave shape.
As shown in FIG. 2, the bottom wall of the scanner casing 20 is formed in a substantially flat shape, and an emission window 30 through which a laser beam is emitted is formed in the vicinity of the rear end portion.

  In the scanner unit 17, a laser beam (see the chain line in FIG. 1) based on the image data emitted from the laser light emitting unit is reflected by the polygon mirror 21, and the lens 22, the reflecting mirror 24, the reflecting mirror 25, and the lens 23. Then, the light passes through or reflects through the reflecting mirror 26 and is emitted from the exit window 30. The laser beam emitted from the emission window 30 is applied to the photosensitive drum 44 by high-speed scanning.

The scanner units 17 are arranged so as to overlap each other in a substantially vertical direction. More specifically, each scanner unit 17 is disposed above and corresponding to each developing unit 18, that is, each developing unit 18 and each scanner unit 17 alternately overlap in a substantially vertical direction. Are arranged as follows.
As shown in FIG. 2, the developing unit 18 includes a toner hopper 32 as a developer accommodating portion, a supply roller 33, a developing roller 34 as a developer carrying member, and a layer thickness regulating blade 35 in a developing casing 31. .

Further, the developing unit 18 includes a developing roller 34, a supply roller 33, and an agitator 38 arranged in a substantially horizontal direction, and each developing unit 18 is detachably attached to the main body casing 2 in a substantially horizontal direction. .
As shown in FIGS. 2A and 4A, the developing casing 31 is formed in a substantially elongated box shape whose rear side is opened, and the developing wall 31 is held on the front wall thereof. A grip portion 36 is provided. The grip portion 36 is formed so as to protrude forward from the front wall of the developing casing 31 in a substantially triangular shape when viewed from the side, and its lower surface is formed in a saw shape so that it can be firmly gripped by hand. Yes.

Further, the upper wall of the developing casing 31 is formed in a substantially flat shape parallel to the bottom wall of the scanner casing 20 formed in a substantially flat shape.
Further, the bottom wall is formed in a waveform such that two arcs are continuous in a side view so as to follow the rotation trajectory of the two agitators 38 provided in the toner hopper 23. Further, the rear end portion of the bottom wall is a receiving portion for the supply roller 33 and the developing roller 34. Further, a contact portion 39 that protrudes downward is provided in the vicinity of a position corresponding to the agitator 38 closer to the developing roller 34 on the bottom wall. The abutting portion 39 is formed as a protrusion extending in the width direction of the developing casing 31.

  Further, development side guide projections 37 as engagement members that are slidably engaged with main body side first guide grooves 62 of the main body casing 2 to be described later are provided on the side walls on both sides in the width direction of the development casing 31. . The development-side guide projections 37 are located on both side walls of the development casing 31 in the vicinity of a position corresponding to the development roller 34 and a position corresponding to the agitator 38 farther from the development roller 34 in the substantially horizontal direction. It is formed so as to protrude toward both outer sides in the width direction.

  Further, on both side walls of the developing casing 31, engagement levers 40 are provided as engaged portions. The engaging lever 40 has a hook shape extending in the front-rear direction, a front end portion thereof is formed as a flat operation portion 41, and a rear end portion thereof is a locking groove formed in a side plate 49 of a drum casing 45 described later. It is formed as a hook-like claw portion 42 that can be engaged with the pin 52. The engaging lever 40 is rotatably supported by a rotating shaft 40a provided so as to protrude outward in the width direction in the vicinity of a position corresponding to the agitator 38 closer to the developing roller 34 on both side walls. ing. The engaging lever 40 is applied in a direction in which the claw portion 42 engages with the engaging groove 52, that is, in a counterclockwise direction in FIG. 4, by a spring (not shown) provided in the developing casing 31. It is energized.

  As shown in FIG. 2, the toner hopper 32 is formed as an internal space of the developing casing 31. The toner hopper 32 is provided with two agitators 38 as developer transport members arranged at a predetermined interval in the substantially horizontal direction, and accommodates toner as a developer for each color. That is, in the toner hopper 32, as toner, for each process unit 14, yellow for the yellow process unit 14Y, magenta for the magenta process unit 14M, cyan for the cyan process unit 14C, and black for the black process unit 14K. A positively charged non-magnetic one-component polymer toner having a color is accommodated. Since such a polymerized toner is produced by a suspension polymerization method or an emulsion polymerization method, it has a substantially spherical shape and has a very good fluidity.

The supply roller 33 has a metal roller shaft covered with a roller made of a conductive sponge member. The supply roller 33 is supported in a counterclockwise direction so as to rotate in a direction opposite to the developing roller 34 at a nip portion facing the developing roller 34.
The developing roller 34 is disposed behind the supply roller 33 so as to be compressed with the supply roller 33. In the developing roller 34, a metal roller shaft 67 serving as a guided portion is covered with a roller made of an elastic member such as a conductive rubber material. More specifically, the roller of the developing roller 34 is coated with an elastic roller portion made of conductive urethane rubber, silicone rubber, EPDM rubber or the like containing carbon fine particles, and the surface of the roller portion. , A urethane resin, a polyimide resin, etc. are formed by a two-layer structure with a coat layer whose main component is.

  The developing roller 34 has a roller shaft 67 that rotates in the same direction as the photosensitive drum 44 at a nip portion facing and in contact with the photosensitive drum 44. A drum-side guide groove 51 of the drum casing 43, which will be described later (see FIG. 3). In the vicinity of the rear end portion, it is rotatably supported in the counterclockwise direction. That is, the roller shaft 67 of the developing roller 34 is provided so as to protrude outward in the width direction, and is slidably engaged with a drum-side guide groove 51 described later. A developing bias is applied to the developing roller 34 from a power source (not shown) during development.

  Further, the layer thickness regulating blade 35 includes a pressing portion having a semicircular cross section made of insulating silicone rubber at the tip of a blade body made of a metal leaf spring member. The layer thickness regulating blade 35 has a base end portion of the blade body supported by the developing casing 31 above the supply roller 33 and the developing roller 34, and a pressing portion provided at the tip end portion of the blade body includes a blade They are arranged in contact with each other so that the upper side portion of the developing roller 33 is pressed by the elastic force of the main body.

  Then, the toner stored in the toner hopper 32 is conveyed from the front side to the rear side in the toner hopper 32 by the rotation of the two agitators 38 and is supplied to the supply roller 33. The toner supplied to the supply roller 33 is supplied to the developing roller 34 by the rotation of the supply roller 33. At this time, the toner is positively frictionally charged between the supply roller 33 and the developing roller 34. Further, the toner supplied onto the developing roller 34 enters between the pressing portion of the layer thickness regulating blade 35 and the developing roller 34 as the developing roller 34 rotates, and is developed as a thin layer having a constant thickness. It is carried on a roller 34.

Further, the developing units 18 are arranged so as to overlap each other in the vertical direction. More specifically, as described above, the developing units 18 and the scanner units 17 are arranged above the paper feed tray 11 so as to alternately overlap in the vertical direction.
The photosensitive drum unit 19 is detachably attached to the main casing 2 for each photosensitive drum unit 19, and includes a photosensitive drum 44 as an image carrier and a scorotron charger 45 in the drum casing 43.

As shown in FIG. 2A and FIG. 4A, the drum casing 43 extends forward from the drum housing portion 46 having a substantially rectangular frame shape whose front-rear direction is opened in a penetrating manner, A cover portion 47 as a substantially U-shaped covering portion that is opened upward is integrally formed.
The upper wall of the drum housing portion 46 is formed in a flat plate shape that is substantially flush with the upper wall of the developing casing 31. Further, the bottom wall is formed in an arc shape in a side view along the outer peripheral surface of the photosensitive drum 44, and a contact portion 48 protruding downward is provided at the front end portion and the rear end portion, respectively. Yes. The contact portions 48 are formed at both end portions in the width direction of the drum housing portion 46. That is, four contact portions 48 are provided on the bottom wall of the drum housing portion 46.

Further, the cover portion 47 is continuous from the lower portion of both side walls of the drum housing portion 46, and has a substantially triangular side plate 49 provided opposite to each other, and a lower plate 50 that connects between the lower end portions of the side plates 49. Are integrally formed.
The side plate 49 is formed with a drum-side guide groove 51 as a first guide portion that is recessed in a substantially elongated U shape toward the rear in the middle in the up-down direction, and in the middle of the drum-side guide groove 51 in the front-back direction. A locking groove 52 is formed as a notch-shaped engaging portion that is recessed downward. Also, below the front end of the side plate 49, drum-side guide protrusions 53 that are slidably engaged with main body side third guide grooves 65 (see FIG. 5) of the main body casing 2 to be described later are provided on both outer sides in the width direction. Protrusively.

  A boss portion 61 slidably engaged with a guide groove 29 (see FIG. 3) of the scanner side guide portion 28 of the scanner unit 17 is provided at a substantially central portion in the width direction in the middle of the lower plate 50 in the front-rear direction. It is formed so as to protrude downward. Further, a contact portion 48 that protrudes downward is provided at the front end portion of the lower plate 50. The contact portions 48 are formed at both ends in the width direction of the bottom wall of the cover portion 47. That is, the lower plate 50 is provided with two contact portions 48.

Each contact portion 48 formed on the drum casing 43 is formed such that the free end portion thereof is substantially flush with the substantially horizontal direction, and the boss portion 61 is more than the contact portions 48. It is short.
The photosensitive drum 44 is made of a cylindrical metal tube made of aluminum or the like, and the surface thereof is coated with a photosensitive layer made of an organic photoreceptor mainly composed of polycarbonate. The photosensitive drum 44 can be rotated clockwise through the rotation shaft 63 on both side walls of the drum housing portion 46 so that the photosensitive drum 44 rotates in the same direction as the conveyance belt 56 at the nip portion facing the conveyance belt 56. It is supported.

The rotating shaft 63 is provided so as to protrude further outward in the width direction from both side walls of the drum housing portion 46, and is slidably engaged with a main body side second guide groove 64 described later.
The scorotron charger 45 is fixed to the upper wall of the drum housing portion 46 at a predetermined interval above the photosensitive drum 44 above the photosensitive drum 44. The scorotron charger 45 is a positively charged scorotron charger that generates corona discharge from a charging wire such as tungsten, and the surface of the photosensitive drum 44 is made uniform by applying a voltage from a power source (not shown). It is provided so that it can be charged positively.

  When the photosensitive drum 44 is rotated, first, the surface of the photosensitive drum 44 is positively charged uniformly by the scorotron charger 45. Thereafter, as the photosensitive drum 44 rotates, the surface of the photosensitive drum 44 is scanned with a laser beam from the scanner unit 17 at a high speed, thereby forming an electrostatic latent image based on the image data. After that, when facing the developing roller 34, the positively charged toner carried on the developing roller 34 is electrostatically charged on the surface of the photosensitive drum 44, that is, uniformly charged positively. The surface of the photosensitive drum 44 is exposed to a laser beam and electrically moved to a portion where the potential is lowered to be visualized, whereby reversal development is achieved. As a result, a toner image for each color is formed on the photosensitive drum 44.

Further, the photosensitive drum units 19 are arranged so as to overlap each other in a substantially vertical direction, and in a state where the developing units 18 are mounted, the photosensitive drums 44 are substantially horizontal to the developing rollers 34 of the developing units 18. It is arranged so as to face each other.
As shown in FIG. 1, the transfer unit 15 is provided in the main body casing 2 so as to face each photosensitive drum 44 on the opposite side of each developing unit 18 in each photosensitive drum 44 arranged in a substantially vertical direction. ing. The transfer unit 15 includes a transfer driving roller 54, a transfer driven roller 55, a transport belt 56 formed of an endless belt, and a transfer roller 57.

The transfer driving roller 54 is disposed below the photosensitive drum 44 of the yellow process section 14Y and on the side rear side of the paper feed roller 12. The transfer driven roller 55 is disposed above the photosensitive drum 44 of the black process unit 14 </ b> K and obliquely rearward below the fixing unit 16.
The conveyor belt 56 is made of conductive polycarbonate or polyimide resin in which conductive particles such as carbon are dispersed, and is wound between the transfer driving roller 54 and the transfer driven roller 55. The conveyor belt 56 is disposed such that the outer contact surface that is wound is in contact with the entire photosensitive drum 44 of each process unit 14.

Then, the transfer driven roller 55 is driven by the drive of the transfer drive roller 54, and the conveyance belt 56 contacts the photosensitive drum 44 of each process unit 14 between the transfer drive roller 54 and the transfer driven roller 55. The surface is rotated in the counterclockwise direction so as to rotate in the same direction as the photosensitive drum 44.
Further, the transfer roller 57 is provided so as to face the photosensitive drum 44 of each process unit 14 in the substantially horizontal direction with the conveyor belt 56 interposed therebetween in the wound conveyor belt 56. In the transfer roller 57, a metal roller shaft is covered with a roller made of an elastic member such as a conductive rubber material. Further, the transfer roller 57 is provided so as to be able to rotate counterclockwise so as to rotate in the same direction as the circumferential movement direction of the transport belt 56 on the contact surface facing and contacting the transport belt 56. A transfer bias is applied from a power source (not shown).

  The transfer portion 15 is integrally supported by the rear cover 8 of the main body casing 2. Therefore, as shown by the phantom line, when the rear cover 8 is opened, the transfer unit 15 rotates about the transfer driving roller 54 as a fulcrum, and is moved integrally with the opened rear cover 8. When 8 is closed, the transfer unit 15 rotates with the transfer driving roller 54 as a fulcrum, and the conveyor belt 56 is pressed against each photosensitive drum 44.

  Then, the sheet 3 fed from the sheet feeding unit 4 is circulated and moved by the driving of the transfer driving roller 54 and the driven of the transfer driven roller 55 from the lower side to the upper side by the guide of the conveying roller 13. 56 and the photosensitive drum 44 of each process unit 14 are sequentially passed, and while passing, the toner images for each color formed on the photosensitive drum 44 of each process unit 14 are sequentially transferred, As a result, a color image is formed on the paper 3.

  That is, for example, when a yellow toner image formed on the photosensitive drum 44 of the yellow process unit 14Y is transferred to the paper 3, then a magenta toner image formed on the photosensitive drum 44 of the magenta process unit 14M. Are transferred onto the paper 3 on which the yellow toner image has already been transferred, and the same operation is performed by the cyan toner image formed by the cyan process unit 14C and the black toner image formed by the black process unit 14. Are superimposed and transferred, whereby a color image is formed on the paper 3.

In the formation of such a color image, the color laser printer 1 has a tandem apparatus configuration that includes a photosensitive drum 44 for each color. Therefore, the toner image for each color is formed at substantially the same speed as that for forming a monochrome image. To achieve rapid color image formation.
The fixing unit 16 is provided above the process unit 14 and the transfer unit 15 and on the downstream side in the transport direction of the paper 3. The fixing unit 16 includes a heating roller 58 and a pressing roller 59. The heating roller 58 is made of a metal base tube having a release layer formed on the surface thereof, and a halogen lamp is provided along the axial direction thereof. Then, the surface of the heating roller 58 is heated to the fixing temperature by the halogen lamp. The pressing roller 59 is provided so as to press the heating roller 58.

The color image transferred onto the paper 3 is then thermally fixed in the fixing unit 16 while the paper 3 passes between the heating roller 58 and the pressing roller 59.
The paper discharge unit 6 includes the paper discharge port 9 and the paper discharge tray 10 described above. The heat-fixed sheet 3 is discharged from the discharge outlet 9 to the outside of the main casing 2 and stacked on the discharge tray 10.

  In the color laser printer 1, the transfer residual toner is collected by a so-called cleanerless development system in which the transfer residual toner remaining on the photosensitive drum 44 after the transfer is collected by the developing roller 34 in each process unit 14. I am doing so. That is, in the cleanerless development method, after the transfer, the surface of the photosensitive drum 44 having the transfer residual toner is charged at a charging position facing the scorotron charger 45 by the rotation of the photosensitive drum 44, and then The exposure is performed by the scanner unit 17. The untransferred toner in the unexposed portion that has not been exposed is electrically collected by the developing roller 34 when the surface of the photosensitive drum 44 faces the developing roller 34. On the other hand, in the exposed portion, a toner image is formed by the transfer residual toner and the toner from the developing roller 34. According to such a cleanerless developing system, a waste toner storage unit for collecting and storing the transfer residual toner can be made unnecessary. Therefore, it is possible to reduce the size of the developing unit 18 and the photosensitive drum unit 19 without requiring a space for providing the waste toner storage portion. Therefore, the developing unit 18 and the photosensitive drum unit 19 can be attached and detached from the side opposite to the transfer side. Furthermore, the area for installing the color laser printer 1 can be reduced by arranging the developing unit 18 and the scanner unit 17 so as to overlap each other in the substantially vertical direction.

In this embodiment, the developing roller 34 rotates with respect to the photosensitive drum 44 at a peripheral speed 1.6 times. The difference in peripheral speed makes it easy to collect the transfer residual toner from the photosensitive drum 44 to the developing roller 34.
Further, in the color laser printer 1, side plates 66 (see FIG. 3) are provided on both sides in the width direction inside the main body casing 2, and each side plate 66 corresponds to each process unit 14, As shown in FIG. 5, the development side guide projection 37 of the development casing 31 is slidably engaged with the main body side first guide groove 62 as a second guide portion, the rotating shaft 63 of the photosensitive drum 44, and the drum casing. A main body side second guide groove 64 and a main body side third guide groove 65 are formed as third guide portions to which the drum side guide protrusions 53 of 43 are slidably engaged.

  Each main body side first guide groove 62 is formed to face each side plate 66 so that the developing casing 31 is arranged in parallel at a predetermined interval below the scanner casing 20. The front end portion of the main body side first guide groove 62 is formed so as to be opened forward in the open state of the front cover 7, and the rear end portion of the main body side first guide groove 62 is formed on the developing roller 34. When the roller shaft 67 is disposed at the front end opening portion (that is, the guidance start position) of the drum-side guide groove 51 of the drum casing 43, at the position where the development-side guide protrusion 37 on the rear side of the development casing 31 is disposed, It forms so that it may open | release toward back, and between the front-end part and the rear-end part is formed in the substantially horizontal direction.

  Further, each main body side second guide groove 64 is formed to face each side plate 66 so as to be arranged in parallel at a predetermined interval below each main body side first guide groove 62 ( (See FIG. 3). The front end portion of the main body side second guide groove 64 is formed so as to open frontward when the front cover 7 is open, and the rear end portion of the main body side second guide groove 64 is formed by the photosensitive drum 44. When arranged so as to face and contact the conveyor belt 56, the photosensitive drum 44 is formed in a substantially U shape in side view at a position where the rotating shaft 63 abuts, and a substantially horizontal direction is formed between the front end portion and the rear end portion. Is formed.

  Each main body side third guide groove 65 is formed to face each side plate 66 so as to be arranged in parallel with a predetermined interval below each main body side second guide groove 64. The front end portion of the main body side third guide groove 65 is formed so as to be opened forward in the opened state of the front cover 7, and the rear end portion of the main body side third guide groove 65 is formed on the photosensitive drum 44. When the rotary shaft 63 hits the rear end portion of the main body side second guide groove 64, the drum side guide projection 53 of the drum casing 43 is formed in a substantially U shape in side view so as not to hit the front end portion. A space between the rear end portion is formed in a substantially horizontal direction.

  In the color laser printer 1, the developing unit 18 can be attached to and detached from the photosensitive drum unit 19, and the developing unit 18 and the photosensitive drum unit 19 can be attached to and detached from the main body casing 2. The developing unit 18 can be attached to and detached from the photosensitive drum unit 19 with the photosensitive drum unit 19 mounted on the main casing 2.

  That is, the developing unit 18 is attached to and detached from the photosensitive drum unit 19 as shown in FIG. When the developing unit 18 is attached to the photosensitive drum unit 19 in a state where it is removed from the main casing 2, the developing casing 31 is first detached from the drum casing 43 shown in FIG. Then, the operation portion 41 of the engagement lever 40 is pushed downward against the biasing force of the spring, and the engagement lever 40 is rotated to position the claw portion 42 upward. Thereafter, the developing unit 18 is inserted rearward, whereby the roller shaft 67 of the developing roller 34 is inserted into the drum-side guide groove 51 of the drum casing 43 as shown in FIG. Is inserted to the vicinity of the rear end portion of the drum-side guide groove 51. Thereafter, when the hand is released from the operation unit 41, the operation unit 41 is pulled upward by the biasing force of the spring. As a result, the claw portion 42 of the engagement lever 40 is engaged in the locking groove 52 of the drum casing 43, thereby developing the photosensitive drum unit 19 with the developing roller 34 facing the photosensitive drum 44. A unit 18 is mounted.

  The engaging groove 52 is configured so that the developing unit 18 can move slightly in the front-rear direction with respect to the photosensitive drum unit 19, for example, about 1 mm, in a state in which the engaging groove 52 is engaged. The claw portion 42 is formed in a size that can move about 1 mm in the front-rear direction. Further, the drum-side guide groove 51 is formed so that the roller shaft 67 does not contact the rear end portion of the drum-side guide groove 51. Is formed.

  Further, when the developing unit 18 is detached from the photosensitive drum unit 19 in a state where it is detached from the main body casing 2, first, the developing casing 31 is mounted on the drum casing 43 shown in FIG. From the state, the operation portion 41 of the engagement lever 40 is pressed downward against the biasing force of the spring, and the engagement lever 40 is rotated to disengage the claw portion 42 from the engagement groove 52. To do. Thereafter, by pulling the developing unit 18 forward, the roller shaft 67 of the developing roller 34 is retracted forward from the drum-side guide groove 51 of the drum casing 43 as shown in FIG. Then, the roller shaft 67 of the developing roller 34 is pulled out from the drum side guide groove 51 of the drum casing 43, and thereby the developing unit 18 with respect to the photosensitive drum unit 19 in a state where the developing unit 18 is removed from the main body casing 2. Is desorbed.

By attaching and detaching in this way, the developing unit 18 can be attached to and detached from the photosensitive drum unit 19 by engaging and disengaging the claw portion 42 of the engaging lever 40 provided in the developing casing 31 and the engaging groove 52 provided in the drum casing 43. Can be planned.
In such attachment and detachment, the engagement / disengagement between the claw portion 42 and the locking groove 52 can be operated by the operation portion 41 of the engagement lever 40 of the developing casing 31. That is, the attaching / detaching operation of the developing unit 18 with respect to the photosensitive drum unit 19 can be operated from the front side. Therefore, the attachment / detachment work can be facilitated and the operability can be improved.

  Then, the development unit 18 and the photosensitive drum unit 19 are integrally attached to and detached from the main body casing 2, for example, referring to the black process section 14K in FIG. When mounting, first, the front cover 7 is opened, the photosensitive drum unit 19 and the developing unit 18 in the mounted state are engaged, and the developing side guide protrusion 37 of the developing casing 31 is engaged with the main body side first guide groove 62. In the state where the rotating shaft 63 of the photosensitive drum 44 is engaged with the main body side second guide groove 64 and the drum side guide protrusion 53 of the drum casing 43 is engaged with the main body side third guide groove 65, Until the rotating shaft 63 of the photosensitive drum 44 abuts against the rear end portion of the second guide groove 64 on the main body side. To.

  Then, the main body side first guide groove 62, the main body side second guide groove 64, and the main body side third guide groove 65 allow the developing side guide protrusion 37 of the developing casing 31, the rotating shaft 63 of the photosensitive drum 44, and the drum of the drum casing 43 to be used. The side guide protrusions 53 are respectively guided substantially rearward in the horizontal direction. Further, when the drum casing 43 faces the scanner side guide portion 28 provided in the scanner casing 20, it is guided by the scanner side guide portion 28, and subsequently, the boss portion 61 of the cover portion 47 of the drum casing 43 is connected to the scanner casing 20. 2, the boss portion 61 is engaged with the locking groove 29 of the scanner side guide portion 28, whereby the boss portion 61 is guided to the locking groove 52 (FIG. 2). (See (b)). Thereafter, the rotating shaft 63 of the photosensitive drum 44 abuts against the rear end portion of the main body side second guide groove 64, and the photosensitive drum 44 is mounted on the main body casing 2 as a unit in a state of facing the conveying belt 56. The

  In the state where the developing unit 18 and the photosensitive drum unit 19 are mounted on the main body casing 2 in this way, the rotating shaft 63 of the photosensitive drum 44 is formed in the main body side second guide groove 64 as shown in FIG. The rotation shaft 63 gets over the upper portion of a pressing spring 68 (shown only in FIG. 6) provided in the main body casing 2 just before hitting the rear end. When the rotation shaft 63 of the photosensitive drum 44 is in contact with the rear end portion of the main body-side second guide groove 64, the pressing spring 68 presses the rotation shaft 63 rearward, so that the conveyance belt 56 is pressed against. The photosensitive drum 44 can be positioned so as to contact. Further, in the main casing 2, a pressing lever 69 (shown only in FIG. 6) is formed with a contact shaft 70 (shown only in FIG. 6) formed so as to protrude on both sides in the width direction at the rear of the developing casing 31. Are provided so that they can be pressed rearward.

The pressing lever 69 is moved to a retracted position indicated by a virtual line and a pressing position indicated by a solid line by driving a motor (not shown). When the photosensitive drum 44 rotates, the photosensitive drum 44 is moved to the pressing position, and when the photosensitive drum 44 stops rotating, the photosensitive drum 44 is moved to the retracted position. Thereby, the developing roller 34 can be positioned so as to be surely brought into contact with the photosensitive drum 44.
The pressing lever 69 may be interlocked with the opening / closing of the front cover 7 instead of the motor.

In this mounted state, as shown in FIG. 1, the grip portion 36 is disposed so as to protrude forward from the scanner unit 17 in a substantially vertical direction, and a space is provided above the grip portion 36.
Further, when the photosensitive drum unit 19 and the developing unit 18 are integrally detached from the main body casing 2, as shown in FIG. 5, first, the front cover 7 is opened and the photosensitive drum unit in the mounted state. 19 and the developing unit 18 are slid forward while gripping the grip portion 36.

  Then, the rotating shaft 63 of the photosensitive drum 44 is moved forward over the upper portion of the pressing spring 68 against the pressing force of the pressing spring 68, and the boss portion 61 is substantially horizontal by the locking groove 29 of the scanner side guide portion 28. The developing side guide protrusion 37 of the developing casing 31 and the rotating shaft 63 of the photosensitive drum 44 are guided by the main body side first guide groove 62, the main body side second guide groove 64, and the main body side third guide groove 65. The drum side guide protrusions 53 of the drum casing 43 are guided substantially in the front in the horizontal direction, and the photosensitive drum unit 19 and the developing unit 18 that are attached to each other are pulled out from the main body casing 2 as a whole. The developing unit 18 is detached from the main casing 2 as a whole.

  For example, referring to FIG. 5, the cyan process unit 14 </ b> C is referred to for attaching / detaching the developing unit 18 to / from the photosensitive drum unit 19 in a state where the photosensitive drum unit 19 is attached to the main casing 2. As described above, in the state where the photosensitive drum unit 19 and the developing unit 18 that are attached to each other are attached to the main casing 2, first, the front cover 7 is opened, and development is performed as shown in FIG. The operation part 41 of the engagement lever 40 of the casing 31 is pressed downward to release the engagement of the claw part 42 with the locking groove 52. Thereafter, the grip portion 36 is gripped, and the developing unit 18 is slid forward.

  Then, the mounting of the developing unit 18 to the photosensitive drum unit 19 is released, and the roller shaft 67 of the developing roller 34 is pulled out from the drum side guide groove 51 of the drum casing 43 as shown in FIG. Thus, the developing unit 18 is detached. Next, the developing side guide protrusion 37 of the developing casing 31 is guided substantially in the horizontal direction by the main body side first guide groove 62, and the developing unit 18 is pulled out from the main body casing 2. As a result, only the developing unit 18 is detached from the main casing 2.

  When the developing unit 18 is attached to the photosensitive drum unit 19 with the photosensitive drum unit 19 still attached to the main casing 2, first, the front cover 7 is opened, and the developing unit 18 is moved to the first main body side. In a state where the developing side guide protrusion 37 of the developing casing 31 is engaged with the guide groove 62, the gripping portion 36 is gripped and slid rearward.

  Then, the developing-side guide protrusion 37 of the developing casing 31 is guided substantially backward in the horizontal direction by the main body-side first guide groove 62. When the developing side guide protrusion 37 is guided to the rear end portion of the main body side first guide groove 62, the roller shaft 67 of the developing roller 34 is at that position as shown in FIG. It is engaged with the 43 drum side guide grooves 51. Next, the roller shaft 67 is guided to the drum side guide groove 51, whereby the guide of the developing casing 31 is transferred from the main body casing 2 to the drum casing 43.

  Thereafter, as shown in FIG. 4A, the claw portions 42 positioned below by the springs at the positions where the roller shaft 67 is in front of the rear end portion of the drum-side guide groove 51 are arranged on the side plates 49 of the drum casing 43. Abuts against the front end of the. Thereafter, the operation portion 41 is rotated downward, the claw portion 42 of the engagement lever 40 is moved upward, the developing unit 18 is slid rearward, and the roller shaft 67 is located at the rear end position of the drum side guide groove 51. When the operator releases his / her hand from the operation portion 41 at the position, the claw portion 42 is engaged in the locking groove 52 of the drum casing 43 by the biasing force of the spring. As a result, the developing unit 18 is attached to the photosensitive drum unit 19 so that the developing roller 34 faces the photosensitive drum 44.

In this color laser printer 1, the developing unit 18 and the photosensitive drum unit 19 can be integrally attached to and detached from the main body casing 2 as described above, and the photosensitive drum unit 19 remains mounted on the main body casing 2. In this state, the developing unit 18 can be attached to and detached from the photosensitive drum unit 19.
Therefore, in the toner empty state, the used developing unit 18 is detached from the photosensitive drum unit 19 with the photosensitive drum unit 19 mounted on the main casing 2, and then a new developing unit 18 is attached to the photosensitive drum unit 19. By mounting, only the developing unit 18 having a high replacement frequency can be replaced. As a result, the running cost can be reduced and the industrial waste can be reduced rather than replacing the photosensitive drum unit 19 and the developing unit 18 as a single unit. Furthermore, the replacement work of the developing unit 18 can be facilitated.

In the tandem type color laser printer 1 having the photosensitive drum 44 for each color, each color is sequentially transferred by each photosensitive drum 44. Therefore, each photosensitive drum 44 has a positioning accuracy in order to prevent color misregistration between the colors. Therefore, unnecessary attachment / detachment of each photosensitive drum 44 should be avoided.
However, if the developing unit 18 is replaced with the photosensitive drum unit 19 in a state where the photosensitive drum unit 19 is mounted on the main casing 2 in this way, only the developing unit 18 is removed without attaching or detaching the photosensitive drum 44. Can be exchanged. Therefore, it is possible to prevent the positional deviation of each photosensitive drum 44 and form a high-quality color image with little color deviation.

  When the photosensitive drum 44 is replaced, the developing unit 18 and the photosensitive drum unit 19 are detached from the main casing 2 as described above, and then the developing unit 18 is detached from the used photosensitive drum unit 19. Then, after the developing unit 18 is attached to a new photosensitive drum unit 19 and then attached to the main casing 2 as a unit, the photosensitive drum unit 19 having a low replacement frequency can be replaced.

Further, in the color laser printer 1, the developing unit 18 and the photosensitive drum unit 19 are attached and detached on the opposite side of the photosensitive drum 44 from the transfer position to the paper 3, so that interference with the transfer unit 15 can be avoided. Therefore, it is possible to secure the attachment and detachment of the developing unit 18 and the photosensitive drum unit 19.
In such an attaching / detaching operation, the holding unit 36 provided in the developing unit 18 is held and the developing unit 18 alone or both the developing unit 18 and the photosensitive drum unit 19 are attached to and detached from the main body casing 2. be able to. Therefore, operability can be improved.

Further, in this color laser printer 1, since the developing units 18 and the scanner units 17 are alternately arranged, the developing unit 18 alone or both the developing unit 18 and the photosensitive drum unit 19 can be connected to each scanner unit 17. It can be detached from between.
Moreover, in the color laser printer 1, the developing units 18 and the scanner units 17 are alternately arranged in the substantially vertical direction, so that the installation area can be saved.

  Further, in such an attaching / detaching operation, the developing side guide protrusion 37 of the developing casing 31 is guided in the substantially horizontal direction by the main body side first guide groove 62, so that the attaching / detaching operation of the developing unit 18 with respect to the main body casing 2 is ensured. can do. Further, the main body side second guide groove 64 and the main body side third guide groove 65 guide the rotating shaft 63 of the photosensitive drum 44 and the drum side guide protrusion 53 of the drum casing 43 in a substantially horizontal direction. 2 can be secured.

The main body side first guide groove 62, the main body side second guide groove 64, and the main body side third guide groove 65 are provided along the longitudinal direction of the surface of the scanner casing 31 of the scanner unit 17. The unit 18 alone or both the developing unit 18 and the photosensitive drum unit 19 can be attached and detached from between the scanner units 17.
Moreover, the main body side first guide groove 62, the main body side second guide groove 64, and the main body side third guide groove 65 are side plates 66 that face each other on both sides in the width direction of the developing unit 18 (both sides in the axial direction of the developing roller 34). In FIG. 4, the developing unit 18 and the photosensitive drum unit 19 can be guided to be attached to and detached from the main casing 2.

  Further, the development unit 18 is provided with development-side guide protrusions 37 in the vicinity of the position corresponding to the development roller 34 and in the vicinity of the position corresponding to the agitator 38 farther from the development roller 34. By engaging the developing side guide protrusions 37 with the main body side first guide grooves 62, the developing unit 18 can be guided in a state where shakiness in a substantially horizontal direction is prevented. Therefore, even if the developing unit 18 is formed long in the substantially horizontal direction, it is possible to stably attach and detach the main unit casing 2.

  Further, the developing unit 18 is arranged so that the gripping portion 36 protrudes forward from the scanner unit 17 in a substantially vertical direction in a state where the developing unit 18 is attached to the photosensitive drum unit 19 that is attached to the main casing 2. Since the space is provided above the grip portion 36, the grip portion 36 can be easily gripped from the space. Therefore, it is possible to improve the operability during the attaching / detaching operation.

  Further, in the photosensitive drum unit 19, the boss portion 61 of the cover portion 47 is guided by the locking groove 29 of the scanner side guide portion 28 provided in the scanner casing 20, so that the photosensitive drum unit 19 can be more stably attached and detached. Can do. In addition, the scanner-side guide portion 28 that guides the boss portion 61 is formed integrally with the scanner casing 20, that is, the surface of the scanner casing 20 also serves as a guide member for the developing unit 18. The photosensitive drum unit 19 can be attached and detached while reducing the above-mentioned and simplifying the apparatus configuration.

  In the color laser printer 1, when the developing unit 18 is attached to and detached from the photosensitive drum unit 19, the developing roller 34 is exposed to light by the roller shaft 67 of the developing roller 34 being guided by the drum-side guide groove 51 of the photosensitive drum unit 19. It is guided so as to face the drum 44. Therefore, the positional accuracy of the developing roller 34 with respect to the photosensitive drum 44 is good. As a result, it is possible to satisfactorily form a color image.

  Moreover, in this color laser printer 1, when the developing unit 18 is mounted on the photosensitive drum unit 19 with the photosensitive drum unit 19 still mounted on the main casing 2, the developing casing 31 is first the first on the main body side. Due to the engagement between the guide groove 62 and the development side guide projection 37, the roller shaft 67 of the developing roller 34 is guided to the guide start position guided by the drum side guide groove 51. Next, the main body side first guide groove 62 and the development side are developed. While the engagement with the side guide protrusion 37 is released, the roller shaft 67 and the drum side guide groove 51 are engaged, whereby the developing roller 34 is guided to a position where it contacts the photosensitive drum 44. As a result, even if the photosensitive drum unit 19 is mounted on the main casing 2, the developing roller 34 can be disposed with high positional accuracy with respect to the photosensitive drum 44.

  In the color laser printer 1, as shown in FIG. 1, the direction of removing the paper feed tray 11, the display direction of the operation panel 60, and the paper discharge direction of the paper 3 discharged from the paper discharge port 9. Since the detaching direction of the photosensitive drum unit 19 and the developing unit 18 is substantially the same direction, the operator can access all from substantially the same direction in these operations. Therefore, operability can be improved.

In particular, since the discharge direction of the paper 3 and the detaching direction of the developing unit 18 are substantially the same direction, the operator can take out the discharged paper 3 and attach / detach the developing unit 18 from the same direction. can do. Therefore, the operability can be further improved.
In the color laser printer 1, the developing unit 18 and the photosensitive drum unit 19, as shown in FIG. By abutting the abutting portions 48 provided on the bottom wall 46 and abutting the abutting portions 39 provided on the bottom wall in the developing casing 31, these can be stably placed integrally. . Therefore, it is possible to prevent the developing unit 18 and the photosensitive drum unit 19 from overturning and to facilitate the replacement work.

Further, as shown in FIG. 8, the developing unit 18 and the photosensitive drum unit 19 can be placed independently by the contact portions 39 and 48 provided on the developing unit 18 and the photosensitive drum unit 19, respectively. . Therefore, the developing unit 18 and the photosensitive drum unit 19 are easy to handle.
In addition, in the photosensitive drum unit 19, the abutting portion 48 is also provided on the lower plate 50 of the cover portion 47 of the drum casing 43, so that the cover portion 47 covers a part of the developing unit 18 and covers the cover. The contact portion 48 provided on the lower plate 50 of the portion 47 can prevent both the developing unit 18 and the photosensitive drum unit 19 or the photosensitive drum unit 19 alone from being overturned. For this reason, it is possible to prevent both the developing unit 18 and the photosensitive drum unit 19 or the photosensitive drum unit 19 alone from falling while reducing the number of parts with a simple configuration.

Further, in such a color laser printer 1, as shown in FIGS. 9 and 10, a shutter member 73 covers the photosensitive drum 44 so that the transfer position of the photosensitive drum 44 onto the paper 3 can be freely opened and closed. A mechanism 72 (see FIG. 11) can also be provided.
That is, as shown in FIG. 11, the shutter mechanism 72 includes a shutter member 73 provided on each photosensitive drum 44, a swing arm 74 as an engaged portion, a biasing spring 75 as a biasing means, and a main body casing. 2 is provided with a rack member 76 as a shutter moving means, a main body side pinion gear 77, a connecting cam 78 as an engaging portion, and an open / close side pinion gear 79 provided on the rear cover 8.

  The shutter member 73 has a substantially arc shape in cross section, is formed in a plate shape with a width that can cover the photosensitive drum 44 in the axial direction and can be accommodated between both side walls of the drum casing 43. On both sides in the width direction of one end portion of the shutter member 73 (a front end portion at an exposure position described later), connection plates 80 to which the swing arm 74 is connected are formed to protrude outward in the width direction. .

  The swing arm 74 is provided integrally with the shutter member 73 and has a substantially triangular plate shape in which the distal end portion 74a, the one-side base end portion 74b, and the other-side base end portion 74c are arranged in a substantially triangular shape. The drum casing 43 is disposed outside the both side walls. At one base end portion 74 b of the swing arm 74, an insertion hole is formed through which the rotation shaft 63 of the photosensitive drum 44 is inserted. By inserting the insertion hole into the rotation shaft 63, the swing arm 74 is inserted. Is supported so as to be rotatable about the rotation shaft 63 as a fulcrum. Further, a locking projection 81 for locking the biasing spring 75 protrudes outward in the width direction at the other side base end portion 74 c of the swing arm 74. The locking projection 81 is formed to protrude longer in the width direction than the rotating shaft 63. Further, the tip end portion 74 a of the swing arm 74 is joined so as to be continuous with the connecting plate 81 of the shutter member 73.

The urging springs 75 are coil springs and are respectively provided outside the swing arm 74. Coil portions 75a formed in a winding shape are inserted into the rotating shaft 63 and extend linearly from both sides of the coil portions 75a. One side 75 b of the free end is locked to the locking protrusion 81 of the swing arm 74, and the other side is supported by the drum casing 43.
As a result, as shown in FIG. 11, the locking projection 81 of the swing arm 74 is always biased rearward by the biasing spring 75, and the swing arm 75 is biased by the biasing force of the biasing spring 75. 74 is rotated in the clockwise direction, and the shutter member 73 is positioned at a covering position that covers the front surface of the photosensitive drum 44.

The main body side pinion gear 77 and the connecting cam 78 are provided for each photosensitive drum unit 19 on both sides in the width direction of the main body casing 2. The main body side pinion gear 77 and the connecting cam 78 are integrally formed and are rotatably supported in the main body casing 2.
The connecting cam 78 has a substantially disc shape and is formed with a substantially fan-shaped notch 82. The notch 82 is formed so as to be recessed rearward so as to come into contact with the locking projection 81 on the outer side of the shaft end of the rotating shaft 63 when the rear cover 8 is closed.

The main body side pinion gear 77 is provided so as not to rotate relative to the connecting cam 78. A support shaft 83 projecting inward in the width direction from the main body casing 2 is inserted through the center of the main body side pinion gear 77 and the connecting cam 78. The main body side pinion gear 77 and the connecting cam 78 are connected to the support shaft. 83 is supported so as to be rotatable about a fulcrum.
The rack member 76 has a plate shape extending in the vertical direction, and is disposed so as to face each main body side pinion gear 77 on both sides in the width direction of the main body casing 2. In the rack member 76, a plurality of substantially elongated elliptical slide grooves 84 are formed at predetermined intervals in the vertical direction. The main body casing 2 is provided with support pins 85 that are slidably locked in the respective slide grooves 84.

The rack member 76 is supported so as to be slidable in a substantially vertical direction with respect to the main body casing 2 with the support pins 85 slidably received in the slide grooves 84.
Further, in the middle of the front surface of the rack member 76 in the longitudinal direction, first racks 86 that mesh with the main body side pinion gears 77 are formed at positions facing the main body side pinion gears 77, respectively. A second rack 87 that meshes with the transfer side pinion gear 79 is formed at the lower end of the rear surface at a position facing the transfer side pinion gear 79 described below.

The opening and closing side pinion gear 79 is provided on the pivot shaft 88 so as not to rotate relative to the second rack 87 of each rack member 76 at both axial ends of the pivot shaft 88 of the hinge 8 a of the rear cover 8. ing.
In the shutter mechanism 72, first, as shown in FIG. 11, when the photosensitive drum 44 of the photosensitive drum unit 19 is not positioned at the transfer position, the shutter member is biased by the biasing force of the biasing spring 75 as described above. 73 is positioned at a covering position that covers the front surface of the photosensitive drum 44, thereby preventing damage or deterioration of the surface of the photosensitive drum 44.

  Next, as shown in FIG. 12, when the photosensitive drum unit 19 is slid rearward for mounting on the main casing 2 and the photosensitive drum 44 comes near the transfer position, the notch 82 of the connecting cam 78 swings. Abutting on the locking projection 81 of the arm 74, the locking projection 81 is pressed forward as the photosensitive drum unit 19 slides backward. Then, the swing arm 74 rotates counterclockwise against the urging force of the urging spring 75, so that the shutter member 73 that has covered the photosensitive drum 44 on the rear side becomes the drum casing 43. The bottom wall of the drum casing 43 is swung forward and positioned at the exposed position below the bottom wall of the drum casing 43. As a result, the rear surface of the photosensitive drum 44 is exposed to the transfer position.

  Then, as shown in FIG. 13, when the rear cover 8 is opened, the opening / closing side pinion gear 79 is rotated in the direction of the arrow (counterclockwise) by the rotation of the rotation shaft 88 accompanying the opening operation. As a result, the rack member 76 is slid upward through the second rack 87 meshed with the open / close pinion gear 79. Then, the main body side pinion gear 77 meshed with the first rack 86 is rotated in the direction of the arrow (clockwise), so that the connecting cam 78 provided so as not to rotate relative to the main body side pinion gear 77 is also in the direction of the arrow. It is rotated (clockwise). As a result, the shutter member 73 that has exposed the photosensitive drum 44 is swung backward so as to cover the photosensitive drum 44 below the bottom wall of the drum casing 43, and the rear side of the photosensitive drum 44. It is located in the covering position on the other side. As a result, the rear surface of the photosensitive drum 44 is covered from the transfer position.

  In the shutter mechanism 72, when the rear cover 8 is closed again, the open / close side pinion gear 79 is rotated clockwise by the rotation of the rotating shaft 88 in the reverse direction, that is, the closing operation. As a result, the rack member 76 is slid downward through the second rack 87 meshed with the open / close side pinion gear 79. Then, the main body side pinion gear 77 meshed with the first rack 86 is rotated in the counterclockwise direction, so that the connecting cam 78 provided so as not to rotate relative to the main body side pinion gear 77 also rotates in the counterclockwise direction. Is done. As a result, the shutter member 73 is moved from the covering position to the exposure position, and as a result, the rear surface of the photosensitive drum 44 is exposed to the transfer position.

  Subsequently, when the photosensitive drum unit 19 is pulled forward to detach the photosensitive drum unit 19 from the main casing 2, the photosensitive drum 44 is separated forward from the transfer position and swings with the notch 82 of the connecting cam 78. The contact of the arm 74 with the locking projection 81 is released, and the oscillating arm 74 is rotated clockwise by the urging force of the urging spring 75. As a result, the shutter member 73 is moved from the exposure position to the covering position, and damage or deterioration of the surface of the photosensitive drum 44 is prevented.

If such a shutter mechanism 72 is provided, the photosensitive drum 44 can be exposed to the transfer position only when necessary by selective movement of the shutter member 73 to the covering position or the exposure position. Damage and deterioration of the drum 44 can be prevented.
That is, in the shutter mechanism 72, when the rear cover 8 is in the open state, the shutter member 73 is moved to the covering position. Therefore, it is possible to prevent the photosensitive drum 44 from being exposed to the space formed by the opened state of the rear cover 8, and to prevent damage and deterioration of the photosensitive drum 44. On the other hand, when the rear cover 8 is in the closed state, the shutter member 73 is moved to the exposure position. Therefore, the transfer operation can be performed with the photosensitive drum 44 facing the conveyance belt 56 at the transfer position.

  In the shutter mechanism 72, the swing arm 74 provided integrally with the shutter member 73 rotates in conjunction with the opening / closing operation of the rear cover 8 via the opening / closing side pinion gear 79, the rack member 76 and the main body side pinion gear 77. The shutter member 73 can be moved to the covering position or the exposure position by being engaged with and disengaged from the connecting cam 78. Therefore, the shutter member 73 can be moved to the covering position or the exposure position in conjunction with the opening / closing operation of the rear cover 8.

  In the above description, the direct transfer type tandem color laser printer 1 that directly transfers from each photosensitive drum 44 to the paper 3 is exemplified, but the present invention is not limited to this. For example, A toner image of each color may be configured as an intermediate transfer type tandem color laser printer in which a toner image for each color is temporarily transferred from each photosensitive member to an intermediate transfer member as a transfer medium and then transferred to a sheet at once.

  In the above description, in the shutter mechanism 72, the connecting cam 78 is provided in the main body casing 2, and the opening / closing operation of the rear cover 8 and the connecting cam 78 are performed via the open / close pinion gear 79, the rack member 76, and the main body side pinion gear 77. For example, the connecting cam 78 is provided directly on the rear cover 8 without the opening / closing side pinion gear 79, the rack member 76, and the main body side pinion gear 77, and the locking projections of the connecting cam 78 and the swing arm 74 are provided. The shutter member 73 may be selectively moved to the covering position or the exposure position only by engagement with the 81 or release thereof.

  In the color laser printer 1, when the photosensitive drum unit 19 and the developing unit 18 are mounted on the main casing 2, the grip portion 36 projects forward from the scanner unit 17 in the substantially vertical direction as described above. With this arrangement, a space is provided above the grip portion 36 to secure an operation space for the grip portion 36. For example, as shown in FIG. 14, the grip portion 36 is disposed above the scanner. If the photosensitive drum unit 19 and the developing unit 18 are mounted on the main body casing 2 when the developing drum 31 is provided in the lower part of the rear wall of the developing casing 31 so that a space is provided between the holding unit and the unit 17, the grip portion Even if the 36 is arranged so as not to protrude forward from the scanner unit 17, the operation space of the grip portion 36 is ensured. Door can be.

1 is a side sectional view of an essential part showing an embodiment of a color laser printer as an image forming apparatus of the present invention. FIG. 2 is an enlarged cross-sectional side view of a main part in FIG. 1, in which (a) is a state where a developing unit is attached to the photosensitive drum unit, and a state where the photosensitive drum unit is attached to a main body casing; A state in which the developing unit is detached from the photosensitive drum unit in a state where the photosensitive drum unit is mounted on the main casing. It is a principal part sectional view of the color laser printer shown in FIG. FIGS. 2A and 2B are side views of main parts showing the photosensitive drum unit and the developing unit of the color laser printer shown in FIG. 1, in which FIG. 1A shows a state where the developing unit is attached to the photosensitive drum unit, and FIG. On the other hand, the developing unit is detached. FIG. 2 is a side cross-sectional view of a main part of the color laser printer shown in FIG. 1, in which a photosensitive drum unit and a developing unit are attached to and detached from a main casing. FIG. 6 is an enlarged cross-sectional side view of a main part of the color laser printer shown in FIG. 5 with a photosensitive drum unit and a developing unit being attached to and detached from a main body casing. FIG. 2 is a side cross-sectional view of an essential part showing a state where the photosensitive drum unit and the developing unit of the color laser printer shown in FIG. 1 are mounted on a mounting surface in a state where the developing unit is mounted on the photosensitive drum unit. FIG. 2 is a side cross-sectional view of a main part showing a state where the photosensitive drum unit and the developing unit of the color laser printer shown in FIG. 1 are mounted on a mounting surface in a state where the developing unit is detached from the photosensitive drum unit. . FIG. 2 is a cross-sectional side view of a main part of an embodiment in which a shutter mechanism is provided in the color laser printer shown in FIG. FIG. 2 is a sectional side view (rear cover open state) of a main part of an embodiment in which a shutter mechanism is provided in the color laser printer shown in FIG. 1. FIG. 10 is an enlarged side cross-sectional view of the main part of the shutter mechanism of the color laser printer shown in FIG. 9, showing a state where the photosensitive drum unit and the developing unit are detached from the main body casing. FIG. 10 is an enlarged cross-sectional side view of a main part of the shutter mechanism of the color laser printer shown in FIG. 9, showing a closed state of the rear cover. FIG. 10 is an enlarged side cross-sectional view of the main part of the shutter mechanism of the color laser printer shown in FIG. 9, showing the open state of the rear cover. FIG. 5 is an enlarged side sectional view of a main part showing another embodiment of the developing unit of the color laser printer shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color laser printer 2 Main body casing 3 Paper 8 Rear cover 9 Paper discharge port 11 Paper feed tray 17 Scanner unit 18 Developing unit 19 Photosensitive drum unit 20 Scanner casing 32 Toner hopper 34 Developing roller 36 Holding part 37 Developing side guide protrusion 38 Agitator 39 Contact part 41 Operation part 42 Claw part 44 Photosensitive drum 47 Cover part 48 Contact part 51 Drum side guide groove 52 Locking groove 57 Transfer roller 60 Operation panel 62 Main body side first guide groove 64 Main body side second guide groove 65 Main body side third Guide groove 67 Roller shaft 73 Shutter member 75 Biasing spring 76 Rack member 74 Swing arm 78 Connecting cam

Claims (25)

It is formed by developing an electrostatic latent image with a developing portion having a developer containing chamber for containing the developer and a developer carrying member for carrying the developer, and the developer carried on the developer carrying member. An image carrier having an image carrier for carrying a developer image is provided for each of a plurality of colors,
The developing unit is detachably attached to the image carrying unit, the developing unit is attached to the image carrying unit, and the developing unit and the image carrying unit are integrated with each other. It can be attached to and detached from the body
Each of the developing unit and the image carrying unit is provided so that they can be placed together when detached from the image forming apparatus main body, and each of the developing unit and the image carrying unit is placed on the placing surface. An image forming apparatus comprising an abutting portion that abuts.   The image forming apparatus according to claim 1, wherein the developing unit and the image carrying unit are placed independently of each other by the contact unit. The image carrying portion includes a covering portion for covering a part of the developing portion,
The image forming apparatus according to claim 1, wherein the contact portion is provided in the covering portion.   The image forming apparatus according to claim 1, wherein the developing unit is detachably attached to the image carrier mounted on the image forming apparatus main body.   A first opening / closing member provided on the opposite side of the transfer position on the image carrier to which the developer image carried on the image carrier is transferred; 5. The image forming apparatus according to claim 1, wherein the image bearing portion is provided so as to be attached to and detached from an opening formed by opening the first opening / closing member. apparatus.   6. The apparatus according to claim 1, further comprising an engaging portion provided in the image carrying portion and an engaged portion provided in the developing portion so as to be engageable with the engaging portion. The image forming apparatus according to any one of the above.   The image forming apparatus according to claim 1, further comprising: a grip portion provided in the developing portion for gripping the developing portion.   The image forming apparatus according to claim 7, wherein a space is provided above the grip portion in a state where the developing unit is attached to the main body of the image forming apparatus.   The image according to any one of claims 6 to 8, further comprising an operation unit that is provided in the developing unit and releases the engagement between the engaging unit and the engaged unit. Forming equipment.   A first guide portion provided in the image carrying portion, for guiding the developing portion so that the developer carrying body faces the image carrier, and provided in the developing portion; The image forming apparatus according to claim 1, further comprising a guided portion to be guided.   11. The image forming apparatus according to claim 10, further comprising a second guide unit that is provided in the image forming apparatus main body and guides attachment / detachment of the developing unit with respect to the image forming apparatus main body.   The second guide unit is configured to guide the developing unit so that the guided unit of the developing unit is guided to a guide start position of the first guide unit of the image carrier mounted on the image forming apparatus main body. The image forming apparatus according to claim 11, wherein the image forming apparatus guides a part.   13. The image forming apparatus according to claim 11, further comprising a third guide portion provided in the image forming apparatus main body, for guiding the attachment / detachment of the image carrier with respect to the image forming apparatus main body. . Exposure means for exposing the image carrier to form an electrostatic latent image is provided corresponding to each of the image carriers,
The image forming apparatus according to claim 13, wherein the second guide part and the third guide part are provided substantially parallel to a surface of the casing of the exposure unit.   The said 2nd guide part and the said 3rd guide part are provided so that the said developing part may be opposed in the axial direction both sides of the said developer carrier, The Claim 13 or 14 characterized by the above-mentioned. Image forming apparatus. The developer storage chamber includes a plurality of developer transport members provided at predetermined intervals in the attaching / detaching direction,
The developing unit is disposed in the second guide unit in the vicinity of a position corresponding to the developer carrying member and a position corresponding to the developer transport member furthest from the developer carrying member in the attaching / detaching direction. The image forming apparatus according to claim 15, further comprising an engaging member to be engaged. Exposure means for exposing the image carrier to form an electrostatic latent image is provided corresponding to each of the image carriers,
The image forming apparatus according to claim 1, wherein the developing units and the exposure units are alternately arranged.   The image forming apparatus according to claim 17, wherein the developing units and the exposure units are alternately arranged in a substantially vertical direction. A recording medium containing a recording medium to which the developer image is transferred is accommodated. The recording medium accommodating means is provided detachably with respect to the image forming apparatus main body, an operation panel for operating the image forming apparatus, and the recording medium is discharged Recording medium discharge means for
The removal direction of the recording medium storage means, the display direction of the operation panel, the discharge direction of the recording medium discharged from the recording medium discharge unit, and the release direction of the developing unit and the image carrier unit are: The image forming apparatus according to claim 18, wherein the image forming apparatuses are substantially in the same direction.   20. The image forming apparatus according to claim 17, wherein a surface of the casing of the exposure unit also serves as a guide member for the image carrier.   21. The developer remaining on the image carrier after the developer image carried on the image carrier is transferred to a transfer medium is collected by the developer carrier. The image forming apparatus according to any one of the above. Each of the image carrying portions includes a shutter member that is movably provided between a covering position that covers a transfer position to which the carried developer image is transferred, and an exposed position that exposes the transfer position;
The image forming apparatus according to claim 1, further comprising an urging unit that urges the shutter member to a covering position.   A transfer unit that transfers the developer image on the image carrier to a transfer medium at the transfer position; a second opening / closing member that supports the transfer unit and that can be opened and closed on the image forming apparatus body; And a shutter moving means for setting the shutter member to an exposed position when the opening / closing member is in a closed state and setting the shutter member to a covering position when the second opening / closing member is in an open state. The image forming apparatus according to claim 22. A developer image formed by developing the electrostatic latent image with the developer, and an image carrier provided for each color;
A first opening / closing member provided on the opposite side of the transfer position on the image carrier so as to be openable / closable with respect to the image forming apparatus main body;
Transfer means for transferring a developer image on each image carrier to a transfer medium;
A shutter member movably provided between a covering position that covers a transfer position facing the transfer means in the image carrier and an exposed position that exposes the transfer position;
Biasing means for biasing the shutter member to the covering position;
A second opening / closing member that supports the transfer unit and is provided in the image forming apparatus main body so as to be openable and closable;
Shutter moving means for setting the shutter member in an exposed position when the second opening / closing member is in a closed state and setting the shutter member in a covering position when the second opening / closing member is in an open state;
In the closed state of the second opening / closing member, when the image carrier is mounted from the opening formed by opening the first opening / closing member, the shutter member is moved to the exposed position by the shutter moving means. An image forming apparatus.   An engaged portion provided in the shutter member, and an engaging portion provided so as to be engageable with the engaged portion and moving in conjunction with an opening / closing operation of the second opening / closing member. The image forming apparatus according to claim 24.

Images