Patent ID: 12228880

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensions, materials, shapes, relative arrangements, and the like of the components described below are not intended to limit the scope of the present invention only to them unless otherwise specified.

(Image Forming Apparatus)

First, a schematic configuration of an image forming apparatus100will be described with reference toFIGS.1,2, and3.FIG.1is a perspective view of the image forming apparatus100.FIGS.2and3are schematic cross-sectional views of the image forming apparatus inFIG.1. The image forming apparatus100illustrated inFIGS.1to3is a copying machine including a reading device, but the embodiment may be another image forming apparatus such as a printer not including a reading device. In addition, the embodiment is not limited to a color image forming apparatus including a plurality of photosensitive drums2as illustrated inFIGS.2and3, and may be a color image forming apparatus including one photosensitive drum2or an image forming apparatus that forms monochrome images.

The image forming apparatus100illustrated inFIGS.2and3includes four image forming portions1Y,1M,1C, and1K (hereinafter, also collectively and simply referred to as “image forming portions1”) that form toner images of respective colors of yellow, magenta, cyan, and black.

In addition, the image forming portions1Y,1M,1C, and1K respectively include photosensitive drums2Y,2M,2C, and2K (hereinafter, also collectively and simply referred to as “photosensitive drums2”). The photosensitive drum2is an example of a rotating photoreceptor, and may be a photosensitive belt.

In addition, the image forming portions1Y,1M,1C, and1K include charging rollers3Y,3M,3C, and3K (hereinafter, also collectively and simply referred to as “charging rollers3”) as charging portions that respectively charge the photosensitive drums2Y,2M,2C, and2K.

In addition, the image forming portions1Y,1M,1C, and1K include light emitting diode (hereinafter referred to as LED) exposure heads4Y,4M,4C, and4K (hereinafter, also collectively and simply referred to as “exposure heads4”) as exposure portions that expose the photosensitive drums2Y,2M,2C, and2K.

Further, the image forming portions1Y,1M,1C, and1K include development units24Y,24M,24C, and24K (hereinafter, also collectively and simply referred to as “development units24”) as development portions that develop electrostatic latent images on the photosensitive drums2with toner and develop a toner image of each color on the photosensitive drums2. Note that Y, M, C, and K attached to the reference numerals indicate the colors of the toner.

The image forming apparatus100illustrated inFIGS.2and3is an image forming apparatus that adopts a so-called “lower surface exposure system” that exposes the photosensitive drums2from below. In the image forming apparatus100adopting the lower surface exposure system, the exposure head4is disposed below the photosensitive drum2. Hereinafter, a description will be given on the premise of an image forming apparatus adopting a lower surface exposure system. Note that, although not illustrated, an image forming apparatus adopting an “upper surface exposure system” that exposes the photosensitive drums from above may be used as an embodiment.

The image forming apparatus100includes an intermediate transfer belt9to which toner images formed on the photosensitive drums2are transferred, and primary transfer rollers6(Y, M, C, and K) that sequentially transfer the toner images formed on the photosensitive drums2on the intermediate transfer belt9. The intermediate transfer belt9is disposed above the image forming portion1. Note that, in addition to the intermediate transfer method using the intermediate transfer belt9, a direct transfer method of directly transferring from the photosensitive drum2to a sheet may be used.

In addition, the image forming apparatus100includes a secondary transfer roller16that transfers the toner image on the intermediate transfer belt9to a recording sheet P conveyed from a feeding portion11, and a fixing device19as a fixing portion that fixes the secondarily transferred image to the recording sheet P.

In addition, toner bottles22Y,22M,22C, and22K (hereinafter, also collectively and simply referred to as “toner bottles22”) that accommodate replenishment toners of the respective colors are detachably replaceable units with respect to the image forming apparatus100. The toner bottles22are disposed above the intermediate transfer belt9. In the toner bottles22, an appropriate amount of toner is appropriately supplied from the corresponding toner bottle to each development unit included in the four image forming portions by a toner supply mechanism (not illustrated).

In addition, the image forming apparatus100includes the feeding portion11that feeds the recording sheet P. The feeding portion11includes sheet cassettes12aand12b, feeding rollers13aand13b, and a registration roller15. The sheet cassettes12aand12bare disposed below the image forming portion1. The recording sheets P accommodated in the sheet cassettes12aand12bare fed one by one by the feeding rollers13aand13b, and conveyed to a secondary transfer portion T2at a predetermined timing by the registration roller15.

In addition, the image forming apparatus100includes a duct unit60in a detachable manner. The duct unit60is disposed below the image forming portion1and above the feeding portion11. The duct unit60is an exposure cooling unit that communicates with a lifting duct69to be described later and cools the exposure heads4by an airflow through the lifting duct69.

(Image Forming Process)

Next, the image forming process of the image forming apparatus100will be briefly described. The charging roller3Y charges the surface of the photosensitive drum2Y The exposure head4Y exposes the surface of the photosensitive drum2Y charged by the charging roller3Y. As a result, an electrostatic latent image is formed on the photosensitive drum2Y Next, the development unit24Y develops the electrostatic latent image formed on the photosensitive drum2Y with yellow toner. The yellow toner image developed on the surface of the photosensitive drum2Y is transferred onto the intermediate transfer belt9by a primary transfer roller6Y. Magenta, cyan, and black toner images are also formed by a similar image forming process and transferred to be superimposed on the intermediate transfer belt9.

The toner image of each color transferred onto the intermediate transfer belt9is conveyed to the secondary transfer portion T2by the intermediate transfer belt9. The toner images conveyed to the secondary transfer portion T2are collectively transferred to the recording sheet P conveyed from the feeding portion11by the secondary transfer roller16. The recording sheet P to which the toner image is transferred is conveyed to the fixing device19. The fixing device19fixes the toner image on the recording sheet P by heat and pressure. The recording sheet P subjected to the fixing process by the fixing device19is discharged to a discharge tray21disposed above the toner bottle22by a discharge roller20.

(Drum Unit and Development Unit)

A replaceable drum unit23and the development unit24in the image forming apparatus100of the present embodiment will be described by way of example.

The photosensitive drums2and the charging rollers3described above are integrally unitized (drum unit and drum cartridge) together with a cleaning device (not illustrated). An example of the configuration will be described with reference toFIGS.4,5,6, and7.FIGS.4and5are perspective views illustrating schematic structures around the drum units23(Y, M, C, and K) and around the development units24(Y, M, C, and K) included in the image forming apparatus100. In addition,FIG.6is a view illustrating a state in which the drum unit23is inserted into and removed from the image forming apparatus100from the outside of the apparatus body.FIG.7is a view illustrating a state in which the development unit24is inserted into and removed from the image forming apparatus100from the outside of the apparatus body.

The drum unit23Y,23M,23C, and23K (hereinafter, also collectively and simply referred to as “drum units23”) including the photosensitive drums2are attached to the image forming apparatus100. The drum unit23is a cartridge to be replaced by an operator such as a user and a maintenance person. The drum unit23of the present embodiment rotatably supports the photosensitive drum2. Specifically, the photosensitive drum2is rotatably supported by the frame body of the drum unit23. Note that the drum unit23may not include the charging roller3or the cleaning device.

In addition, the development units24Y,24M,24C, and24K (hereinafter, also collectively and simply referred to as “development units24”) separate from the drum units23, which are photoreceptors, are attached to the image forming apparatus100. The development unit24includes development sleeves5Y,5M,5C, and5K (hereinafter, also collectively and simply referred to as “development sleeves5”) as developer carriers that carry the developer, and screws7Y,7M,7C, and7K (hereinafter, also collectively and simply referred to as “screws7”) that supply the developer to the development sleeves5and stirred the developer. The development unit24is a cartridge in which the development sleeve5and the screw7are integrated, and is detached from the apparatus body of the image forming apparatus100and replaced by an operator as illustrated inFIGS.5and7.

Here, the toner is circulated and conveyed at high speed by the screw7inside the development unit24. The rotation speed of the screw7is relatively very high with respect to the rotation speed of the development sleeve5and the photosensitive drum2, and coating on the development sleeve5can be uniformly performed without unevenness.

In addition, the image forming apparatus100includes a cartridge tray30(30Y,30M,30C, and30K) for each image forming portion (seeFIGS.8and9). The drum unit23and the development unit24are supported by the cartridge tray30of each image forming portion, guided in the axial direction of the photosensitive drum, and inserted into and removed from the apparatus body of the image forming apparatus100.

Note that one of the cartridge trays30is attached to a front side plate100F (seeFIG.18) and the other is attached to a back side plate100B (seeFIG.18) in the axial direction of the photosensitive drum. The front side plate100F is formed of sheet metal, and forms a part of a housing of the apparatus body on the near side of the apparatus body of the image forming apparatus100. The back side plate100B is formed of sheet metal, and forms a part of a housing of the apparatus body on the far side of the apparatus body of the image forming apparatus100. The front side plate100F and the back side plate100B are disposed to face each other on one side and the other side in the axial direction of the photosensitive drum, and a beam (sheet metal not illustrated) is bridged between. Here, regarding the image forming apparatus of the present embodiment or the constituent members, the front surface side or the near side is a side on which the drum unit23and the development unit24are taken in and out (inserted and removed) with respect to the apparatus body of the image forming apparatus100.

Since the drum unit23and the development unit24deteriorate due to repetition of the image forming process, they take the form of a unit (cartridge) that can be maintained by replacement or attachment and detachment.

FIG.3illustrates the arrangement of the drum units23, the development units24, and the exposure heads4when replacement or attachment and detachment is performed. In the image forming apparatus illustrated inFIG.3, unlike the image forming apparatus illustrated inFIG.2, it can be seen that the development unit24and the exposure head4are retracted and separated from the photosensitive drum2.

This is because, when the state in which the development unit24and the exposure head4are disposed close to the photosensitive drum2as illustrated inFIG.2is maintained, each unit may be damaged due to dynamic interference at the time of attachment and detachment of the unit, or the unit may not be taken out.

Therefore, at the time of attaching and detaching the unit, the development unit24and the exposure head4are retracted from the photosensitive drum2and separated from each other as illustrated inFIG.3by a retraction mechanism by a development stay31, a rotary arm65, the lifting duct69, and the like, which will be described later.

The drum unit23and the development unit24are inserted into and removed from the near side of the image forming apparatus100, and are mounted at predetermined positions (mounting positions) of the apparatus body of the image forming apparatus100.

The image forming apparatus100includes inner doors102Y,102M,102C, and102K (hereinafter, also collectively and simply referred to as “inner doors102”) that cover the near sides of both the drum unit23and the development unit24mounted at the mounting position. As illustrated inFIGS.8and9, the inner door102has a rotary shaft102apivotally supported on the front side of the cartridge tray30, and is rotatable within a predetermined range with respect to the cartridge tray30. That is, the inner door102is provided to be openable and closable with respect to the image forming apparatus.

The inner door102is a cover that covers one end side in the axial direction of the drum unit23and the development unit24mounted on the image forming apparatus100. Here, one end side in the axial direction is one end side in the axial direction of the photosensitive drum2, and is a side (front surface side or near side) on which the drum unit23and the development unit24are taken in and out (inserted and removed) with respect to the apparatus body of the image forming apparatus100.

The inner door102is a member necessary for protecting each unit and making it difficult for the photosensitive drum2to be exposed to light in a process other than the image forming process, and is disposed at a position facing the front surface in the attachment and detachment direction of each color unit.

Further, a front cover101forming an exterior of the apparatus is provided on the near side of the image forming apparatus100. One end of the front cover101is fixed to the front side of the apparatus body of the image forming apparatus100by a hinge, and is rotatable with respect to the apparatus body of the image forming apparatus100by the hinge. The front cover101is provided on the front side of the inner door102in the axial direction of the photosensitive drum. In the closed state illustrated inFIG.1, the front cover101covers the entire plurality of inner doors102arranged in the left-right direction to form an exterior on the front side of the apparatus.

Therefore, replacement work of the drum unit23and the development unit24is performed by an operator in the following procedure. The operator opens the front cover101as illustrated inFIG.4, then opens the inner door102as illustrated inFIG.5, and takes out the drum unit23(FIG.6) or the development unit24(FIG.7) in the apparatus body. Then, the replacement work is completed by inserting the new drum unit23or the development unit24, closing the inner door102, and further closing the front cover101.

Note that the retraction mechanism of the development unit24and the exposure head4retracts the development unit24and the exposure head4from the photosensitive drum2in conjunction with the operation of opening the inner door102. The retraction mechanism (development stay31, rotary arm65, and lifting duct69) will be described later.

Here, in the following description, the front side plate side is defined as a front side (near side or front surface side), and the back side plate side is defined as a back side (far side or rear surface side) with respect to the apparatus body. In addition, when the photosensitive drum2K on which the electrostatic latent image related to the black toner image is formed is used as a reference, a side on which the photosensitive drum2Y on which the electrostatic latent image related to the yellow toner image is formed is disposed is defined as a left side. In addition, when the photosensitive drum2Y on which the electrostatic latent image related to the yellow toner image is formed is used as a reference, a side on which the photosensitive drum2K on which the electrostatic latent image related to the black toner image is formed is disposed is defined as a right side. Further, a direction perpendicular to the front-back direction and the left-right direction defined here and upward in the vertical direction is defined as an upward direction, and a direction perpendicular to the front-back direction and the left-right direction defined here and downward in the vertical direction is defined as a downward direction. The defined forward direction F, backward direction B, rightward direction R, leftward direction L, upward direction U, and downward direction D are illustrated inFIG.1.

In addition, the axial direction of the photosensitive drum2described in the following description is a direction that coincides with the front-back direction (near-far direction) illustrated inFIG.1. In addition, the longitudinal direction of the exposure head4also coincides with the front-back direction illustrated inFIG.1. That is, the axial direction of the photosensitive drum2and the longitudinal direction of the exposure head4coincide with each other. In addition, one end side in the axial direction of the photosensitive drum2means a front side defined herein, and the other end side means a back side defined herein. One end side and the other end side in the front-back direction also correspond to the front side and the back side defined here. One end side in the left-right direction means a left side defined herein, and the other end side means a right side defined herein.

(Exposure Head)

Next, the exposure head4will be described with reference toFIGS.10to12.FIG.10is a schematic cross-sectional view of the exposure head4included in the image forming apparatus of the present embodiment.FIG.11is a perspective view of the exposure head4as viewed from above.FIG.12is a perspective view of the exposure head4as viewed from below.

The exposure head4has an elongated shape (longitudinal shape) extending in the axial direction of the photosensitive drum2. The exposure head4includes a substrate50, a light emitting element mounted on the substrate50, a lens array52, and a holding member that holds the substrate50and the lens array52. The holding member includes a housing54to be described later and a housing support member55that supports the housing54.

Here, the exposure head4includes an LED51(light emitting diode) as a light emitting portion (light emitting element) that emits light. Note that, in the present embodiment, the light emitting element is a semiconductor LED which is a light emitting diode, but may be, for example, an organic light emitting diode (OLED). This OLED is also called organic electro-luminescence (EL), and is a current-driven light emitting element. The OLEDs are arranged on a line along the main scanning direction (axial direction of the photosensitive drum2) on a thin film transistor (TFT) substrate, for example, and are electrically connected in parallel by power supply wiring similarly provided along the main scanning direction.

Note that, on one surface of the substrate50, the plurality of LEDs51(light emitting portions) is arranged along the rotation axis direction of the photosensitive drum2. On the other surface of the substrate50, an FFC connector57to which one end of a flexible flat cable (hereinafter referred to as FFC) is connected is provided.

The lens array52condenses the light emitted from the light emitting element on the photosensitive drum2. The lens array52is a lens assembly including a plurality of lenses. The plurality of lenses is arranged along the arrangement direction of the plurality of LEDs51. Each lens is a cylindrical rod lens made of glass, and has a light incident surface52bon which the light emitted from the LED51is incident and a light emitting surface52afrom which the light incident from the light incident surface is emitted (seeFIG.10). Note that the material of the lens is not limited to glass, and may be plastic. The shape of the lens is not limited to the cylindrical shape, and may be, for example, a polygonal prism such as a hexagonal prism.

The exposure head4is moved in a direction substantially along the optical axis of the lens (hereinafter, also referred to as an optical axis direction) by the retraction mechanism (the rotary arm65and the lifting duct69illustrated inFIG.13). The optical axis of the lens here means a line connecting the center of the light emitting surface of the lens and the focal point of the lens. The lens array52is a lens assembly including a plurality of lenses, and the “optical axis” described above is an optical axis of an arbitrary lens among the plurality of lenses. Here, strictly speaking, the plurality of lenses included in the lens array52may be slightly inclined to each other. This is due to tolerance during assembly. However, the deviation of the tolerance is not considered in a case where the direction of the optical axis is defined. Therefore, it is considered that the optical axes of the plurality of lenses are in the same direction. The lens array52has a function of condensing the light emitted from the LED51on the surface of the photosensitive drum2.

The attachment position of the lens array52with respect to the housing54is adjusted at the time of assembling the exposure head4in a manner that a distance between the luminescent surface of the LED51and the light incident surface of the lens is substantially equal to a distance between the light emitting surface of the lens and the surface of the photosensitive drum2.

The housing54holds the lens array52and the substrate50. In the present embodiment, the housing54is a metal member formed by bending a plate material obtained by plating a galvanized steel plate or a cold-rolled steel plate. The housing54is made of metal as described above. For example, the housing54is formed by pressing a sheet metal such as an iron thin plate into a U shape.

The housing54has a flat surface portion (facing surface)54U in which the first opening54ainto which the lens array52is inserted is formed. The flat surface portion54U faces the photosensitive drum2in the optical axis direction of the lens of the lens array52. Note that the flat surface portion54U is not limited to a flat surface, and may be a slightly curved surface. In addition, the housing54has an extending portion54R extending in a direction away from the photosensitive drum2from one side in the lateral direction of the flat surface portion54U. In addition, the housing54has an extending portion54L extending in a direction away from the photosensitive drum2from the other side in the lateral direction of the flat surface portion54U.

The extending portion54R and the extending portion54L form a substrate support portion for supporting the substrate50inserted from a second opening54bin the housing54. The flat surface portion54U and the substrate support portions (extending portions54R and54L) are integrated to form the housing54that holds the lens array52and the substrate50, and the cross section is formed in a substantially U shape. Since the housing54is formed in a substantially U shape, the second opening54bis formed on the side opposite to the flat surface portion54U. The second opening54bis formed between the substrate support portions (extending portions54L and54R) extending from the flat surface portion54U to the side away from the photosensitive drum.

The substrate50is inserted from the second opening54b, that is, from the lower side of the U-shaped housing54, and is bonded to the inside of each substrate support portion (the inside of the extending portion54L and the inside of the extending portion54R) with an adhesive.

In addition, the lens array52is also bonded to the flat surface portion54U with an adhesive in a state of being inserted into the first opening54aformed in the flat surface portion54U. Note that the lens array52is fixed to the flat surface portion54U (housing54) after the position and inclination in the focusing direction are adjusted by a jig in a manner that the distance in the focusing direction between all the LEDs51mounted on the substrate50and the lens array52becomes a predetermined value.

The housing support member55supports the housing54holding the substrate50and the lens array52in the longitudinal direction, and is provided integrally with the housing54. The housing support member55is a member having a longitudinal shape extending in the axial direction of the photosensitive drum2. The housing support member55is formed in a U shape as illustrated inFIG.10. The housing support member55is provided with the plurality of openings55ain the longitudinal direction which is the axial direction of the photosensitive drum2.

The opening55aof the housing support member55is provided at a position facing a surface (bottom surface of the substrate50) of the substrate50opposite to the mounting surface (top surface of the substrate50) on which the LED51is mounted.

Since the housing support member55is provided integrally with the housing54, the airflow sent from the duct unit60is blown onto the bottom surface of the substrate50through the opening55aof the housing support member55. Moreover, the airflow blown onto the bottom surface of the substrate50is blown in a direction orthogonal to the bottom surface of the substrate50.

As described above, the airflow blown from the opening55aof the housing support member55to the bottom surface of the substrate50is separated from the development unit24and the drum unit23adjacent to the exposure head4by the housing support member55. Therefore, the airflow for cooling the exposure head4introduced into the bottom surface of the substrate50does not leak to the side of the development unit24adjacent to the exposure head4, and the toner of the development unit24can be suppressed from being scattered inside the image forming apparatus.

In addition, as described above, the housing support member55is provided over the longitudinal direction which is the axial direction of the photosensitive drum2, and has the opening55aat a position facing the bottom surface of the substrate50. As a result, the housing support member55of the exposure head4forms a duct (closed space) that blows the airflow of the duct unit60onto the bottom surface of the substrate50through the opening55aand circulates the airflow in the longitudinal direction of the substrate50, that is, a part of the duct that cools the exposure head4.

As described above, the exposure head4is configured as an integrated head unit by the substrate50including the LED51, the lens array52including a plurality of lenses, the housing54, and the housing support member55.

(Lifting Duct)

The image forming apparatus100includes the lifting duct69. The lifting duct69is an exposure support member that detachably supports the exposure head4, and is provided in the apparatus body of the image forming apparatus100together with the cartridge tray30to be described later.

The lifting duct69is provided between a development support member301that supports the development unit24of the cartridge tray30to be described later and a drum support member302that supports the drum unit23. The lifting duct69is provided to be movable between an exposure position (seeFIG.16) where the photosensitive drum2is exposed and a retraction position (FIG.17) retracted from the exposure position between the development support member301and the drum support member302of the cartridge tray30. Both end portions of the lifting duct69in the longitudinal direction are supported from below by the rotary arm65. The lifting duct69is moved in a direction (moving direction) orthogonal to the axial direction of the photosensitive drum2integrally with the exposure head4by the rotary arm65. The lifting duct69is moved to the exposure position or the retraction position by the rotation of the rotary arm65.

The lifting duct69has a longitudinal shape extending in the front-back direction (the axial direction of the photosensitive drum) similarly to the exposure head4to be able to support the entire exposure head4, and its central portion has a shape having upper and lower openings. The lifting duct69forms a duct in which one opening69a(seeFIG.9) communicates with the opening55aof the exposure head4and the other opening portion64(seeFIG.22) communicates with the opening portion61(seeFIG.19) of the duct unit60. The lifting duct69supports the exposure head4and forms a part of a duct (closed space) that communicates the exposure head4and the duct unit60to form a flow path of an airflow for cooling the exposure head4.

The lifting duct69is formed in a hollow shape having no opening at a position facing the development unit24and the drum unit23and having upper and lower openings (the opening69aand the opening portion64). The lifting duct69communicates the exposure head4and the duct unit60to form a space through which air for cooling the exposure head4circulates, and forms an exposure duct that guides an airflow generated by an intake fan62to be described later along the longitudinal direction of the substrate50.

Accordingly, the lifting duct69allows the airflow from the duct unit60to be described later to circulate through the openings (the opening portion64and the opening69a) to the bottom surface of the substrate50of the exposure head4. Therefore, the lifting duct69can circulate the airflow caused by the duct unit60with respect to the bottom surface of the substrate50of the exposure head4without leaking the airflow to the side of the adjacent development unit24or drum unit23, and the scattering of the toner inside the apparatus can be reduced.

Further, as illustrated inFIG.13, the lifting duct69has a first engagement portion69dand a second engagement portion69ethat are engaged with the rotary arm65at both end portions in the longitudinal direction. The first engagement portion69dis provided outside the openings (the opening portion64and the opening69a) of the lifting duct69on one end side in the longitudinal direction. The second engagement portion69eis provided outside the openings (the opening portion64and the opening69a) of the lifting duct69on the other end side in the longitudinal direction.

Therefore, a region (a range Lm inFIG.13) where the first engagement portion69dis provided and a region (the range Lm inFIG.13) where the second engagement portion69eis provided are provided outside a duct region (a range La inFIG.13) where the openings (the opening portion64and the opening69a) of the lifting duct69are surrounded by duct walls69F and69B. In other words, the duct region (the range La inFIG.13) where the openings of the lifting duct69are surrounded by the duct walls69F and69B is provided between the region (the range Lm inFIG.13) where the first engagement portion69dis provided and the region (the range Lm inFIG.13) where the second engagement portion69eis provided.

Note that a range Lc inFIG.13is a region where the FFC connector57of the exposure head4is provided, and is provided outside a duct region indicated by the range La inFIG.13and between the duct region and a region where the first engagement portion69dindicated by the range Lm inFIG.13is provided.

In addition, the range La forming the duct includes most of the substrate50on which the LED51is mounted, and the exposure head4can be sufficiently cooled by blowing the airflow to the range La. Note that the range Lc is a mounting portion of the FFC connector57of a signal line that transmits a drive signal to the substrate50on which the LEDs51are mounted. The range Lc is not provided with an opening for forming a duct, but is configured to enable necessary and sufficient cooling in the range La as described above.

As a result, the air taken in from the outside of the apparatus by the duct unit60to be described later is blown against the bottom surface of the substrate50from the opening55aof the exposure head4through the lifting duct69. In addition, the airflow blown from the opening55aof the exposure head4to the bottom surface of the substrate50is exhausted to the outside of the apparatus by the duct unit60through the lifting duct69.

(Cartridge Tray)

In addition, the image forming apparatus100includes the cartridge tray30. The cartridge tray30will be described with reference toFIGS.8,9, and13.FIGS.8,9, and13are perspective views of the cartridge tray30.

The cartridge tray30is a support member that supports the drum unit23and the development unit24described above, and guides and supports the attaching and detaching operation along the axial direction of the photosensitive drum2. The cartridge tray30pivotally supports the rotary shaft102aof the inner door102in a manner that the inner door102is rotatable within a predetermined range.

The cartridge tray30is provided for each image forming portion. Each cartridge tray30includes the development support member301that guides and supports the attaching and detaching operation of the development unit24along the axial direction of the photosensitive drum2, and the drum support member302that guides and supports the attaching and detaching operation of the drum unit23along the axial direction of the photosensitive drum2. The development support member301and the drum support member302are members having a longitudinal shape extending in the axial direction of the photosensitive drum2. In the cartridge tray30, the development support member301and the drum support member302are integrally formed. Note that the cartridge tray30is not limited to the configuration provided for each image forming portion.

The lifting duct69is movably disposed between the development support member301and the drum support member302of the cartridge tray30. In the lifting duct69, the first engagement portion69dand the second engagement portion69eat both ends in the longitudinal direction are supported by the rotary arm65from below between the development support member301and the drum support member302. The rotary arm65is rotatably provided on the development support member301of the cartridge tray30. The exposure head4is detachably mounted to the lifting duct69movably disposed on the cartridge tray30. In other words, the cartridge tray30is a support member that supports the exposure head4, and guides and supports the attaching and detaching operation along the axial direction of the photosensitive drum2.

(Development Stay)

The image forming apparatus100includes the development stay31slidable along the axial direction of the photosensitive drum2. The development stay31will be described with reference toFIGS.14and15.FIGS.14and15are side views of the development stay31as viewed from the right direction. InFIG.14, the inner door102is in a closed state, and the development unit24is at a position close to the photosensitive drum2. InFIG.15, the inner door102is in an open state, and the development unit24is at a position retracted from the photosensitive drum2.FIG.16is a cross-sectional view taken along a line X-X inFIG.13, and is a view illustrating a state in which the exposure head4is at an exposure position close to the photosensitive drum2.FIG.17is a cross-sectional view taken along the line X-X inFIG.13, and is a view illustrating a state in which the exposure head4is at a retraction position retracted from the exposure position.

The development stay31as a slide member is provided to be movable in the axial direction of the photosensitive drum2. The development stay31moves in one direction in the axial direction in conjunction with the opening operation of the inner door102, and moves in the other direction in the axial direction in conjunction with the closing operation of the inner door102. The development stay31is provided movably with respect to the development support member301of the cartridge tray30. The development stay31has an elongated shape (longitudinal shape) extending in the axial direction of the photosensitive drum2, and includes a development pressurizing top32, a development pressurizing top33, a development stay link34, an arm retraction member68F, and an arm retraction member68B.

The development stay link34is fixed to the front side end portion of the development stay31and is engaged with the inner door102pivotally supported by the cartridge tray30. The development pressurizing top32is fixed to one side (front side) in the longitudinal direction of the development stay31, and the development pressurizing top33is fixed to the other side (back side) in the longitudinal direction of the development stay31. The development pressurizing top32and the development pressurizing top33are provided at positions facing the development unit24.

The development pressurizing tops32and33are development engagement members that are moved in the same direction by the movement of the development stay31and are engaged with the development unit24. The development pressurizing tops32and33are engaged with the development unit24to move the development unit24to a development position close to the photosensitive drum2(seeFIG.16) or a separated position separated from the photosensitive drum2(seeFIG.17).

The inner door102includes a link engagement portion102bthat is engaged with the development stay link34. In the inner door102, the link engagement portion102bis provided on the side opposite to the portion covering the unit via the rotary shaft102a.

As illustrated inFIG.15, in a state where the inner door102is opened, the link engagement portion102bengaged with the development stay link34is positioned closer to the rear end of the inner door102than the rotary shaft102a. On the other hand, as illustrated inFIG.14, in a state where the inner door102is closed, the link engagement portion102bis positioned closer to the lower end of the inner door102than the rotary shaft102a. Therefore, according to the rotation of the inner door102, the link engagement portion102bof the inner door102moves in the rotation direction along a locus of a circle having a radius that is the distance between the rotary shaft102aand the link engagement portion102b. That is, as illustrated inFIG.15, by opening the inner door102, the link engagement portion102balso rotates and moves to the apparatus back side.

As a result, the development stay link34engaged with the link engagement portion102bof the inner door102is slid in the direction of an arrow B which is the apparatus back side, and the two development pressurizing tops32and33integrally configured through the development stay31are also slid in the direction of the arrow B. This means that, as illustrated inFIG.15, the two development pressurizing tops32and33are out of the holding position where the development unit24is held. When the development pressurizing tops32and33deviate from the holding position, the development unit24moves in a direction of an arrow D, which is a direction in which the development pressurizing tops32and33are retracted from the photosensitive drum2by their own weight.

From the above description, it can be seen that the development unit24retracts from the photosensitive drum2in conjunction with the operation of opening the inner door102. Note that, when the inner door102is closed, the development unit24is moved in the direction of the photosensitive drum2and pressed through a procedure reverse to the opening operation.

In this manner, as illustrated inFIG.14, the development stay31is slid and moved in the forward direction F in conjunction with the operation of closing the inner door102. At this time, the development pressurizing top32and the development pressurizing top33are engaged with the development unit24, and the development unit24is moved upward (arrow U) along the inclined surfaces of the development pressurizing top32and the development pressurizing top33of the development stay31. As a result, the development sleeve5of the development unit24is moved in a direction approaching the photosensitive drum2of the drum unit23, and the development sleeve5is moved to a development position (seeFIG.16) approaching the photosensitive drum2.

In addition, as illustrated inFIG.15, the development stay31is slid in the backward direction B in conjunction with the operation of opening the inner door102. At this time, the development pressurizing top32and the development pressurizing top33are engaged with the development unit24, and the development unit24is moved downward (arrow D) along the inclined surfaces of the development pressurizing top32and the development pressurizing top33of the development stay31. As a result, the development sleeve5of the development unit24is moved in a direction away from the photosensitive drum2of the drum unit23, and the development sleeve5is moved to a separated position (seeFIG.17) separated from the photosensitive drum2. At the time of non-development illustrated inFIG.15, the development sleeve5is separated from the photosensitive drum2as compared with the time of development illustrated inFIG.14.

Further, the development stay31includes the arm retraction member68F and the arm retraction member68B for rotating the rotary arm65which is a rotary member. The arm retraction member68F and the arm retraction member68B are integrally formed with the development stay31. The arm retraction member68F is fixed to one side (apparatus front side) in the longitudinal direction of the development stay31, and is provided on a surface on the opposite side of the development pressurizing top32. The arm retraction member68B is fixed to the other side (apparatus back side) in the longitudinal direction of the development stay31, and is provided on a surface on the opposite side of the development pressurizing top33. The arm retraction members68F and68B as the engagement members are moved in the same direction by the development stay31being slid in the front-back direction in conjunction with the opening and closing operation of the inner door102, and are engaged with or disengaged from the rotary arm65to rotate the rotary arm65.

That is, when the development stay31moves in one direction in the axial direction (backward direction B illustrated inFIG.15) in conjunction with the opening operation of the inner door102, the arm retraction member68F and the arm retraction member68B are moved in the same direction and are engaged with the rotary arm65. As a result, the rotary arm65rotates in one direction to move the exposure head4to the retraction position integrally with the lifting duct69. On the other hand, when the development stay31moves in the other direction in the axial direction (forward direction F illustrated inFIG.14) in conjunction with the closing operation of the inner door102, the arm retraction member68F and the arm retraction member68B are moved in the same direction and are disengaged with the rotary arm65. As a result, the rotary arm65rotates in the other direction to move the exposure head4to the exposure position integrally with the lifting duct69.

(Rotary Arm)

Note that the rotary arm65is a rotary member that moves the exposure head4between the exposure position (seeFIG.16) close to the photosensitive drum2and the retraction position (seeFIG.17) retracted from the exposure position.

The rotary arm65, which is a rotary member, is rotatably provided on the development support member301of the cartridge tray30. One end portion of the rotary arm65in the left-right direction orthogonal to the axial direction of the photosensitive drum2is rotatably supported about an axis parallel to the axial direction. In addition, the rotary arm65supports engagement portions69dand69ehaving other end portions in the left-right direction that are both end portions of a region (the range Lm inFIG.13) outside the openings (the opening69aand the opening portion64) of the lifting duct69in the axial direction.

The rotary arm65presses the base surfaces of the first engagement portion69dand the second engagement portion69eat both ends in the longitudinal direction of the lifting duct69upward by the force of an arm pressure spring (not illustrated) which is a biasing member. InFIG.16, the exposure head4is disposed close to the photosensitive drum2, and this is maintained by the rotary arm65pressing the base surfaces of the first engagement portion69dand the second engagement portion69eat both ends of the lifting duct69upward. This pressing is secured by a predetermined spring pressure by the arm pressure spring.

In this manner, the rotary arm65does not directly press the exposure head4but presses the lifting duct69that supports the exposure head4.

The rotary arm65rotates about a rotary shaft in response to the slide movement of the development stay31, and moves the exposure head4to the exposure position (seeFIG.16) or the retraction position (seeFIG.17). That is, in conjunction with the operation of opening and closing the inner door102, the rotary arm65rotates in one direction to move the exposure head4to the exposure position where the photosensitive drum2is exposed, and rotates in the other direction to move the exposure head4to the retraction position retracted from the exposure position.

The rotary arm65constituting a moving mechanism for moving the exposure head4to the exposure position and the retraction position is provided outside a duct region (the range La illustrated inFIG.13) of the exposure head. Therefore, air does not become an obstacle when air is sent from the lower side of the exposure head4to the duct region, and air can be directly blown onto the bottom surface of the substrate50of the exposure head4. As a result, the substrate50including the light emitting element of the exposure head4can be more effectively cooled.

Note that the operation of the rotary arm65that moves the exposure head4to the exposure position or the retraction position is powered by the slide movement of the development stay31that retracts the development unit24, but may be powered via another member linked with the inner door102.

(Duct Unit)

In addition, the image forming apparatus100includes the duct unit60in a detachable manner. The duct unit60will be described with reference toFIGS.18and19.FIG.18is a cross-sectional view of the image forming apparatus taken along the line C-C inFIG.2.FIG.19is a perspective view of the duct unit as viewed from above.

The duct unit60is an exposure cooling unit that communicates with the opening portion64formed by the cartridge tray30and the lifting duct69and cools the exposure heads4by an airflow through the lifting duct69.

Note that, as described above, the lifting duct69is formed in a hollow shape having upper and lower openings (the opening69aand the opening portion64). The lifting duct69forms a duct (exposure duct) in which one opening69acommunicates with the opening55aof the exposure head4and the other opening portion64communicates with the opening portion61of the duct unit60. The lifting duct69communicates the exposure head4and the duct unit60to form an exposure duct that forms a space through which air for cooling the exposure head4circulates.

The duct unit60includes an exhaust duct206as a first duct that communicates with the lifting duct69and forms a space through which the air introduced from the lifting duct69circulates. The exhaust duct206communicates with the lifting duct69and a development duct to be described later, and exhausts the air introduced from the lifting duct69and exhausts the air introduced from the development duct. The exhaust duct206includes an exposure exhaust port202(Y, M, C, and K) as a first exposure introduction port that communicates with the lifting duct69and introduces air from the lifting duct69for each exposure head. The exposure exhaust port202is provided on the upper surface of the exhaust duct206disposed closer to the back side of the image forming apparatus100.

The duct unit60has an exhaust port204that exhausts air from the exhaust duct206to the outside of the image forming apparatus. The exhaust port204is provided at the end portion of the exhaust duct206to face an exterior cover forming an outer surface (here, a left side surface) of the image forming apparatus.

The duct unit60includes an exhaust fan63that circulates air inside the exhaust duct206to generate an airflow to be exhausted from the exhaust port204. The exhaust fan63is disposed at the exhaust port204of the exhaust duct206.

The exhaust port204and the exposure exhaust port202(Y, M, C, and K) for each exposure head are connected by the exhaust duct206. The duct unit60is configured to exhaust air introduced from each exposure exhaust port202by the exhaust fan63to the outside of the image forming apparatus from the exhaust port204through the exhaust duct206.

The duct unit60includes an intake duct205as a second duct that communicates with the lifting duct69to form a space through which the air introduced into the lifting duct69circulates and guides the airflow generated by the intake fan62to the lifting duct69. The duct unit60includes an exposure intake port201(Y, M, C, and K) as a second exposure introduction port that communicates with the lifting duct69and introduces air to the lifting duct69for each exposure head. The exposure intake port201is provided on the upper surface of the intake duct205disposed closer to the front side of the image forming apparatus100.

The duct unit60has an intake port203that takes in air to the intake duct205from the outside of the image forming apparatus. The intake port203is provided at the end portion of the intake duct205to face an exterior cover forming an outer surface (here, a left side surface) of the image forming apparatus.

The duct unit60includes the intake fan62that generates an airflow that takes in air from the intake port203and circulates the air inside the intake duct205. The intake fan62is a first fan that generates an airflow for cooling the exposure head. The intake fan62is disposed at the intake port203of the intake duct205.

The intake port203and the exposure intake port201(Y, M, C, and K) for each exposure head are connected by the intake duct205. The duct unit60is configured to take in air (fresh air) outside the image forming apparatus introduced from the intake port203by the intake fan62from each exposure intake port201through the intake duct205.

The exhaust duct206of the duct unit60is provided on one side (far side) from the center in the axial direction of the photosensitive drum2. The intake duct205of the duct unit60is provided on the other side (near side) from the center in the axial direction of the photosensitive drum2.

The duct unit60is integrally provided with the intake fan62, the exhaust fan63, the intake duct205, and the exhaust duct206, and is detachably mounted to the apparatus body of the image forming apparatus100immediately below the cartridge tray30.

In addition, the duct unit60includes the intake port203and the exhaust port204on the same surface (left surface) side of the image forming apparatus100, and the intake fan62is disposed in the intake port203and the exhaust fan63is disposed in the exhaust port204. In the present embodiment, as illustrated inFIG.18, the intake fan62disposed closer to the front side of the image forming apparatus100functions as an intake fan that takes in air outside the apparatus, and the exhaust fan63disposed closer to the back side functions as an exhaust fan that exhausts air to the outside of the apparatus.

In the exterior cover forming the exterior of the left side surface of the image forming apparatus, a louver (not illustrated) as openings (a first opening and a second opening) are formed at positions facing each of the fans62and63. The louver formed in the exterior cover communicates with the intake port203and the exhaust port204in which the fans62and63are disposed, respectively. Intake by the intake fan62and exhaust by the exhaust fan63are performed through a louver formed in the exterior cover forming the exterior of the left side surface of the image forming apparatus.

Note that, as illustrated inFIG.19, the duct unit60has an opening portion61(Y, M, C, and K) in its upper surface for each exposure head. The opening portion61of the duct unit60includes the exposure intake port201provided closer to the apparatus front side and the exposure exhaust port202provided closer to the apparatus back side. The opening portion61(Y, M, C, and K) of the duct unit60is provided to correspond to each of the exposure heads4of the respective colors.

That is, the opening portion60Y of the duct unit60includes the exposure intake port201Y provided closer to the apparatus front side and the exposure exhaust port202Y provided closer to the apparatus back side. The opening portion60M of the duct unit60includes the exposure intake port201M provided closer to the apparatus front side and the exposure exhaust port202M provided closer to the apparatus back side. The opening portion60C of the duct unit60includes the exposure intake port201C provided closer to the apparatus front side and the exposure exhaust port202C provided closer to the apparatus back side. The opening portion60K of the duct unit60includes the exposure intake port201K provided closer to the apparatus front side and the exposure exhaust port202K provided closer to the apparatus back side.

The opening portion61of the duct unit60is provided at a position facing the opening portion64of the lifting duct69for each exposure head, and is connected to the opening portion64to communicate with the exposure head4to form a closed space.

(Cooling Configuration of Development Unit and Exposure Head)

Next, a cooling configuration of the development unit24and the exposure head4will be described with reference toFIGS.18,19,20,21,22, and23.FIG.20is a cross-sectional view of an intake side of an exposure cooling airflow.FIG.21is a cross-sectional view of the development cooling airflow taken along a line A-A inFIG.2.FIG.22is a cross-sectional view of the exposure cooling airflow along a line B-B inFIG.2.FIG.23is a cross-sectional view of an exhaust side of the development cooling airflow and the exposure cooling airflow. Note that, inFIG.18, the flow of air for cooling the development unit24is indicated by a solid line, and the flow of air indicated by a solid line is also referred to as the development cooling airflow. In addition, inFIG.18, the flow of air for cooling the exposure head is indicated by a broken line, and the flow of air indicated by a broken line is also referred to as the exposure cooling airflow

The development unit24includes the screw7rotating at a high speed and the toner circulating at a high speed as described above, and with this operation, frictional heat is generated in the bearing portion of the screw7and the toner, and the frictional heat is stored in the development unit24, and the temperature rises. When the image formation is completed, the heat storage of the development unit24is completed, and the development unit24is gradually cooled. However, while the image formation is continued, the heat storage is performed as long as the heat capacity of the development unit24allows, and the temperature rises. Since the toner has a property of being easily melted by heat, in a case where the temperature of the development unit24rises to a certain temperature or higher, the toner is fused inside the development unit24, and a coating failure of the development sleeve5occurs, in a manner that the toner image is disturbed, leading to an image failure.

Accordingly, there is a need for a cooling configuration of the development unit24that cools the development unit24in a manner that the temperature of the development unit24does not rise to a certain temperature or higher.

Since the exposure head4dissipates heat according to the emitted light quantity from the LED (light emitting element)51and is disposed close to the development unit24using toner weak against heat, a cooling portion is required. In particular, in a case where the image forming process is repeated at a high frequency, that is, in a case where the image forming process is used in a device with high productivity, or in a case where an image with high density is continuously output, the light emission time is long, and the emitted light quantity is also large. Therefore, the amount of heat generated from the LED51and the circuit on the substrate50on which the LED51is mounted also increases.

As a countermeasure against this, for example, the housing54of the exposure head4is also used as a heat sink, and the exposure head4is configured in a manner that heat dissipation is easy and heat storage is difficult. However, even in such a case, it is conceivable that the cooling of the exposure head4is not in time, heat storage proceeds, and the heat dissipated to the periphery also increases. As a result, the toner around the development sleeve5included in the development unit24and a part of the circulation toner inside the development unit24are fused, which may affect the toner coating layer on the surface of the development sleeve5, leading to an image defect.

Even in a case where the configuration for cooling the development unit24is provided, it is easily assumed that the heat storage caused by the light emission of the LED51is superior in a portion where the exposure head4of the development unit24is close. Therefore, it is desirable to provide a cooling configuration (exposure cooling airflow) of the exposure head4for cooling the exposure head4and discharging heat to the outside of the apparatus separately from the cooling configuration (development cooling airflow) of the development unit24to suppress the amount of heat dissipated to the periphery of the exposure head4.

Here, in configuring the cooling portion of the exposure head4, consideration needs to be given from a certain viewpoint. As illustrated inFIG.8, the development unit24and the development sleeve5of the development unit24are disposed adjacent to the exposure head4. The surface of the development sleeve5is coated with toner, and due to its structure, the toner adheres to the periphery of the bearing portions at both ends of the sleeve, and the toner also adheres to the periphery of the development unit24. This is because the development sleeve5and the screw7are rotated at a high speed, the stirred toner goes up, and the toner is separated from the surfaces of the development sleeve5and the screw7. In addition, due to an increase in the internal pressure of the development unit24caused by high-speed rotation of the development sleeve5and the screw7, toner may be ejected from the gap of the development unit24to the outside.

Therefore, the cooling configuration of the exposure head4is desirably a configuration in which these toners are not caught in the exposure cooling airflow and are not mixed. In other words, in configuring the exposure cooling airflow separately from the development cooling airflow, it is desirable that the toner around the development unit24adjacent to the exposure head4is not caught and not mixed.

From the above, it is preferable that the cooling of the development unit24and the cooling of the exposure head4are performed in different paths. However, if the cooling paths are configured with different paths, it is necessary to secure two cooling paths, and the configuration of the image forming apparatus becomes complicated. Therefore, in order to simplify the configuration of the image forming apparatus without mixing the scattered toner of the development unit around the exposure head4, the present embodiment has the following configuration.

First, the exposure cooling airflow will be described with reference toFIG.18, and next, the development cooling airflow will be described.

(Exposure Cooling Airflow)

First, the exposure cooling airflow will be described. The image forming apparatus100includes the exposure head4, the lifting duct69, the cartridge tray30, and the duct unit60. The exposure head4is mounted to the lifting duct69disposed in the image forming apparatus100, and is integrated with the lifting duct69. When the exposure head4is mounted to the lifting duct69, the opening55a(seeFIG.12) of the housing support member55of the exposure head4communicates with one opening69a(seeFIG.9) of the lifting duct69. The lifting duct69is disposed between the development support member301and the drum support member302of the cartridge tray30and forms a duct that communicates the exposure head4and the duct unit60together with the cartridge tray30. The duct unit60is mounted immediately below the cartridge tray30with respect to the image forming apparatus100. In other words, the duct unit60is provided on the side opposite to the photosensitive drum2across the exposure head4. When the duct unit60is mounted to the image forming apparatus100, the opening portion61(seeFIG.19) of the duct unit60communicates with the other opening portion64(seeFIG.13) of the lifting duct69.

In this manner, the housing support member55, the lifting duct69, and the cartridge tray30, and the duct unit60of the exposure head4form a second cooling duct which is one continuous closed space. Each exposure head4is cooled by the exposure cooling airflow (broken lines shown inFIGS.18and22) flowing through the one closed space formed by the housing support member55, the lifting duct69, the cartridge tray30, and the duct unit60.

As illustrated inFIG.18, a fan62disposed closer to the apparatus front side functions as an intake fan that takes in air (fresh air) outside the apparatus into the duct unit60. A fan63disposed closer to the apparatus back side functions as an exhaust fan that exhausts air inside the duct unit60to the outside of the apparatus.

In an exposure cooling airflow indicated by a broken line inFIG.18, when the fan62and the fan63rotate, air outside the image forming apparatus is introduced from the intake port203through a louver (not illustrated) provided in the exterior cover of the image forming apparatus. As illustrated inFIG.20, the air introduced from the intake port203is exhausted from each exposure intake port201through the intake duct205. The air exhausted from each exposure intake port201is blown to the exposure head4through the lifting duct69. As illustrated inFIG.22, the air blown to the exposure head4through the lifting duct69circulates from the apparatus front side to the back side along the axial direction of the photosensitive drum2, and is introduced into the exhaust duct206from each exposure exhaust port202through the lifting duct69. As illustrated inFIGS.22and23, air introduced from each exposure exhaust port202to the exhaust duct206is exhausted from exhaust port204of the exhaust duct206to the outside of the apparatus through a louver (not illustrated) provided in the exterior cover.

As described above, the duct unit60, the cartridge tray30, the lifting duct69, and the housing support member55form a continuous closed space to constitute an exposure cooling airflow. As illustrated inFIGS.18and19, the intake fan62and the exhaust fan63of the duct unit60face the outside of the apparatus only through the exterior cover of the apparatus. The flow path of the exposure cooling airflow is completed by a minimum path formed by directly taking in air from the louver of the exterior cover into the duct unit60and directly exhausting air from the duct unit60. Accordingly, due to the configuration, the intake and exhaust flow hardly affects the atmosphere air inside the apparatus.

(Development Cooling Airflow)

Next, the development cooling airflow will be described. The image forming apparatus100includes a fan40, which is a second fan that generates an airflow for cooling the development unit24, and a front surface duct41for sending air from the outside of the apparatus to each development unit24. The image forming apparatus100includes a development duct that forms a space for circulating air for cooling the development unit24along the rotation axis direction of the photosensitive drum2. That is, the development duct guides the airflow generated by the fan40along the rotation axis direction of the development unit24. Here, a space formed by the base surface of the development unit24and the upper surface of the cartridge tray30facing the base surface constitutes the development duct.

In the development duct formed by the development unit24and the cartridge tray30, one side in the axial direction which is the apparatus front side communicates with the front surface duct41. In the development duct, the other side in the axial direction, which is the apparatus back side, communicates with the exhaust duct206of the duct unit60to form one closed space.

As illustrated inFIG.19, the exhaust duct206includes, for each development unit, a development exhaust port212(Y, M, C, and K) as a first development introduction port that communicates with the development duct and introduces air from the development duct. The development exhaust port212is provided on the upper surface of the exhaust duct206disposed closer to the back side of the image forming apparatus100.

In addition, the exposure exhaust port202for each exposure head and the development exhaust port212for each development unit are arranged side by side in the left-right direction (first direction) orthogonal to the axial direction of the photosensitive drum2for each image forming portion1with respect to the upper surface of the exhaust duct206.

On the other hand, the development duct of each development unit has an opening35(Y, M, C, and K) connected to each development exhaust port212of the duct unit60. The opening35(Y, M, C, and K) of each development duct is provided in the cartridge tray30for each development unit, and is provided at a position facing each development exhaust port212(Y, M, C, and K) of the duct unit60.

Therefore, the duct unit60exhausts the air introduced from the exposure exhaust port202of the exposure duct and the air introduced from the development exhaust port212of the development duct from the exhaust port204to the outside of the apparatus through the exhaust duct206. That is, the exhaust duct206of the duct unit60that exhausts the air introduced from each exposure head4also serves as an exhaust duct that exhausts the air introduced from the development duct of each development unit.

The fan40is provided on the right side of the front surface of the apparatus body of the image forming apparatus100, and sucks air outside the apparatus from an intake port101aprovided on the right side surface side of the image forming apparatus100of the front cover101. The front surface duct41is disposed inside the front cover101and extends in the left-right direction, which is the direction in which the development units24are arranged. The front surface duct41has an opening41aat a position corresponding to each development unit24. Each opening41aof the front surface duct41is provided at a position facing an opening102cof each inner door102in the axial direction of the photosensitive drum, and communicates with each other by closing the front cover101. The opening102cof each inner door102is provided at a position corresponding to the opening on one end side in the longitudinal direction of the development duct of each development unit24, and communicates with each other by closing the inner door102.

The opening35(Y, M, C, and K) of each development duct is provided closer to the apparatus back side in the axial direction of the photosensitive drum2. When the duct unit60is mounted to the image forming apparatus100, the opening35(Y, M, C, and K) of each development duct communicates with each development exhaust port212(Y, M, C, and K) of the exhaust duct206provided at a position corresponding to each opening35.

As described above, the development duct, which is a closed space formed between the development unit24and the cartridge tray30, forms a part of a duct, which is one closed space communicating with the front surface duct41and the exhaust duct206of the duct unit60. The development duct formed between the development unit24and the cartridge tray30, and the front surface duct41and the exhaust duct206of the duct unit60communicating with the development duct form a first cooling duct that is the one closed space serving as a flow path of the development cooling airflow.

As illustrated inFIG.18, the fan40disposed closer to the right side of the apparatus front surface functions as an intake fan that takes in air (fresh air) outside the apparatus into the apparatus. On the other hand, the fan63disposed closer to the apparatus back side in the duct unit functions as an exhaust fan that exhausts air inside the duct unit60to the outside of the apparatus, similarly to the exposure cooling airflow.

In the development cooling airflow indicated by the solid line inFIG.18, when the fan40and the exhaust fan63rotate, air outside the apparatus is introduced from the intake port101aprovided in the front cover101of the image forming apparatus. The air introduced from the intake port101ais introduced into the development duct of each development unit via each opening41aof the front surface duct41disposed inside the front cover101and the opening102cof each inner door102. As illustrated inFIG.21, the air introduced into the development duct of each development unit circulates from the apparatus front side to the apparatus back side along the axial direction of the photosensitive drum2, and is introduced into the exhaust duct206from each development exhaust port212through the opening35of each development duct. As illustrated inFIGS.22and23, air introduced from each development exhaust port212to the exhaust duct206is exhausted from exhaust port204of the exhaust duct206to the outside of the apparatus through a louver (not illustrated) provided in the exterior cover.

As described above, according to the present embodiment, the exhaust duct206of the duct unit60that exhausts the air introduced from each exposure head4also serves as an exhaust duct that exhausts the air introduced from the development duct of each development unit. In other words, the exhaust fan63and the exhaust duct206are made common. As a result, the air circulating through the development duct to cool the development unit24and the air circulating through the exposure duct to cool the exposure head4join the exhaust duct206of the duct unit60, and are exhausted from the same exhaust port204to the outside of the apparatus by the same exhaust fan63. That is, even if the exposure duct forming the path for cooling the exposure head4is provided separately from the development duct forming the path for cooling the development unit24, the configuration of the image forming apparatus can be simplified by making the exhaust fan and a part of the duct (exhaust duct) common. In addition, it is possible to realize space saving inside the image forming apparatus by performing exhaust by merging the ducts into one exhaust duct.

Note that, in a case where the intake fan and the exhaust fan are used with the same strength, since there is only one exhaust air for the intake air on the development unit side and the intake air on the exposure head side, the exhaust capacity becomes smaller than the intake capacity. In this case, air that cannot be exhausted from the exhaust fan may leak out of the path through a gap in the path. Therefore, it is desirable that the intake amount and the exhaust amount of the cooling configuration of the development unit and the exposure head are equal to each other.

In addition, in the above-described embodiment, the image forming apparatus adopting the lower surface exposure has been described as an example, but the configuration according to the present invention is not limited to this embodiment. For example, an image forming apparatus employing upper surface exposure may be used. In this case, a photosensitive drum is disposed on an upper portion of the intermediate transfer belt, and an exposure head is further disposed on the upper portion of the photosensitive drum, and the upper and lower sides of the photosensitive drum are all opposite to those of the image forming apparatus adopting the lower surface exposure.

In addition, the image forming apparatus is not limited to a laser type image forming apparatus, and may be an inkjet type image forming apparatus or another type image forming apparatus.

Furthermore, note that the operation of the rotary arm65that moves the exposure head4to the exposure position or the retraction position is powered by the movement of the development stay31that moves the development unit24to the development position or the separated position, but may be powered via another member linked with the inner door102.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2022-153984, filed Sep. 27, 2022, which is hereby incorporated by reference herein in its entirety.