Photoconductor cartridge and image forming apparatus

In an image forming apparatus, a photoconductor cartridge including a photoconductor is removably installed in a housing, a transfer unit configured to transfer a developer image onto a sheet in a transfer position is disposed in contact with the photoconductor, a developer cartridge is removably installed in the housing, and a fixing unit is configured to fix a developer image on the sheet in a fixing position. The housing has a first opening provided behind the transfer unit opposite to the photoconductor, and a second opening provided separate from the first opening. The photoconductor cartridge can be removed from and installed into the housing through the to first opening. The developer cartridge can be removed from and installed into the housing through the second opening. The photoconductor cartridge includes a chute that extends between the transfer position and the fixing unit to guide the sheet toward the fixing unit.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority from Japanese Patent Application No. 2014-135651 filed on Jul. 1, 2014, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Apparatuses disclosed herein relate to a photoconductor cartridge detachably attached to a housing and an image forming apparatus including such a photoconductor cartridge.

BACKGROUND ART

An image forming apparatus known in the art typically comprises a photoconductor cartridge, a transfer unit, and a fixing unit (fuser assembly). The photoconductor cartridge includes a photoconductor. The transfer unit is in contact with the photoconductor. In the image forming apparatus, a sheet is nipped between the photoconductor and the transfer unit and passed therethrough, and then forwarded into the fixing unit. The photoconductor cartridge is configured to be installable in, and removable from, the housing of the image forming apparatus, through an opening formed at a rear side of the housing.

In order to achieve a stable conveyance of a sheet into the fixing unit, a chute may be provided to guide the sheet being conveyed from the photoconductor toward the fixing unit. The accurate position of the chute relative to the sheet being conveyed toward the fixing unit is critical because improperly positioned chute would undermine the stability of conveyance of the sheet into the fixing unit.

SUMMARY

In one aspect, an image forming apparatus is provided in which a sheet nipped between a photoconductor and a transfer unit, and passed therethrough can be conveyed toward a fixing unit in a stable manner.

More specifically, according to one or more of embodiments, an image forming apparatus comprises a housing, a photoconductor cartridge, a transfer unit, a developer cartridge, and a fixing unit. The photoconductor cartridge includes a photoconductor configured to carry a developer image. The photoconductor cartridge is removably installed in the housing. The transfer unit is disposed in contact with the photoconductor. The transfer unit is configured to transfer the developer image from the photoconductor onto a sheet in a transfer position. The developer cartridge is configured to store developer to be supplied to the photoconductor. The developer cartridge is removably installed in the housing. The fixing unit is configured to fix the developer image on the sheet in a fixing position. The housing has a first opening and a second opening. The first opening is provided behind the transfer unit opposite to the photoconductor to allow the photoconductor cartridge to be removed from and installed into the housing through the first opening. The second opening is provided separate from the first opening to allow the developer cartridge to be removed from and installed into the housing through the second opening. The photoconductor cartridge includes a chute that extends between the transfer to position and the fixing unit to guide the sheet toward the fixing unit.

In another aspect, a photoconductor cartridge is provided which comprises a photoconductor, a transfer unit and a chute. The transfer unit is disposed in contact with the photoconductor. The transfer unit is configured to transfer a developer image onto a sheet in a transfer position. The chute extends downstream in a sheet conveyance direction to guide the sheet conveyed from the transfer position. The chute has a downstream end facing downstream in the sheet conveyance direction, and the chute includes a first comb-like portion provided at the downstream end.

DESCRIPTION OF EMBODIMENTS

A detailed description will be given of illustrative, non-limiting embodiments with reference made to the drawings where appropriate. In the following description, a general setup of a laser printer1will be described at the outset, and specific configurations of a photoconductor cartridge and associated structures will be described in detail.

In the following description, the direction is designated as inFIG. 1; the left-hand side of the drawing sheet corresponds to the “front” side of the printer, the right-hand side of the drawing sheet corresponds to the “rear” side of the printer, the back side of the drawing sheet corresponds to the “left” side of the printer, and the front side of the drawing sheet corresponds to the “right” side of the printer. The upper/lower (top/bottom) sides of the drawing sheet corresponds to the “upper/under or top/bottom” sides of the printer, and the direction of a line extending upward and/or downward is referred to as “upward-downward direction”.

As shown inFIG. 1, the laser printer1mainly includes a housing2, a feeder unit3, an to LED unit4, a process unit5, and a fixing unit8.

The housing2is provided with a front cover21and a rear cover22. The front cover21and the rear cover22are configured to be swingable with respect to the housing2. The housing2has a front opening21A and a rear opening22A. The front opening21A is a through hole provided at a front side of the housing2, and the rear opening22A is a through hole provided at a rear side of the housing2. The front cover21is disposed to cover and close the front opening21A and can be swung open; thus, the front opening21A is openably closable by the front cover21. The rear cover22is disposed to cover and close the rear opening22A and can be swung open; thus, the rear opening22A is openably closable by the rear cover22. The front opening21A is an example of a second opening, and the rear opening22A is an example of a first opening. Through the front opening21A, sheets (e.g., of paper) can be set in the housing2. A display unit23configured to display an operation status of the laser printer1is disposed on an upper surface on a front side of the housing2.

The feeder unit3is located in a lower space inside the housing2, and includes a sheet feed tray31on which sheets33can be placed, and a sheet feed mechanism32configured to feed a sheet33on the sheet feed tray31.

The sheet feed tray31is configured to include a rack31A disposed in a lower space within the housing2, and the front cover21described above. The sheet feed mechanism32mainly includes a sheet feed roller32A, a separation roller32B, and a separation pad32C.

In the feeder unit3, sheets33placed on the sheet feed tray31are fed by the sheet feed roller32A and separated one sheet from others between the separation roller32B and the separation pad32C, and conveyed toward the process unit5.

The LED unit4, which is an example of an exposure unit, is provided in the housing2and disposed opposite to a peripheral surface of a photoconductor drum61as an example of a photoconductor which will be described later. The LED unit4includes a plurality of light-emitting elements (not shown) arranged in a lateral direction (in an axial direction of the photoconductor drum61).

The process unit5is located in a rear-side space (substantially at the center thereof) within the housing2, and provided above the sheet feed mechanism32. The process unit5includes a photoconductor cartridge6, a development cartridge7as an example of a developer cartridge.

The photoconductor cartridge6is configured to be removable from and installable in the housing2through the rear opening22A, and includes a photoconductor drum61, a charger62, to and a transfer roller63as an example of a transfer unit. The development cartridge7is configured to be removable from and installable in the housing2through the front opening21A, and includes a development roller71and a supply roller72.

In the development cartridge7, toner as an example of developer stored in a toner storage chamber is supplied to the development roller71, and frictionally electrified, by the supply roller72, and carried on the development roller71. In the photoconductor cartridge6, the peripheral surface of the rotating photoconductor drum61is uniformly charged by the charger62and then exposed to light by the LED unit4. In this way, an electrostatic latent image formulated based upon image data is formed on the peripheral surface of the photoconductor drum61.

Subsequently, this electrostatic latent image is supplied with toner carried on the development roller71, and a toner image is formed on the peripheral surface of the photoconductor drum61. Thereafter, a sheet33is conveyed through between the photoconductor drum61and the transfer roller63, so that the toner image carried on the peripheral surface of the photoconductor drum61is transferred onto the sheet33.

The fixing unit8is disposed above the photoconductor cartridge6. The fixing unit8mainly includes a heating roller81and a pressure roller82.

The fixing unit8is configured to thermally fix toner transferred on the sheet33while the sheet33is forwarded through between the heating roller81and the pressure roller82. The sheet33with toner thermally fixed thereon is conveyed to an ejection roller9disposed downstream of the fixing unit8, and ejected from this ejection roller9onto a sheet output tray24.

Next, the structures and arrangement of and around the photoconductor cartridge6and the fixing unit8will be described in detail. The photoconductor cartridge6includes a photoconductor frame69, as an example of a frame, which is configured to support the photoconductor drum61, charger62and transfer roller63described above.

The photoconductor drum61has a peripheral surface of which substantially half is exposed through the photoconductor frame69. This exposed region of the peripheral surface of the photoconductor drum61is opposed to the LED unit4and the development roller71. The LED unit4is disposed behind the photoconductor drum61opposite to the rear opening22A (i.e., the LED unit4and the rear opening22A are disposed on opposite sides with the photoconductor drum61between), and the development roller71is disposed behind the photoconductor drum61opposite to the fixing unit8(i.e. the development roller71and the fixing unit8are disposed on opposite sides with the photoconductor drum61between).

The charger62is disposed above the photoconductor drum61, that is, on a fixing-unit side that is one of opposite sides with respect to the photoconductor61on which the fixing unit8is disposed. The transfer roller63is provided in a rear space within the photoconductor frame69, and in contact with the peripheral surface of the photoconductor drum61at an obliquely-rear-and-lower side of the photoconductor drum61. The rear opening22A described above is disposed behind the transfer roller63opposite to the photoconductor drum61(i.e., the rear opening22A and the photoconductor drum61are on opposite sides with the transfer roller63between).

A handle69A is provided at a rear side of the photoconductor frame69to provide a grip to be held or grasped by a user when the photoconductor cartridge6is carried or manipulated. The handle69A extends rearward from the photoconductor frame69, and is disposed, as shown inFIG. 3, in such a position that the handle69A overlaps the transfer roller63as viewed from the rear side.

As shown inFIG. 2, the photoconductor frame69includes left and right sidewalls69B, and a first contact portion69C as an example of a first engageable portion is provided at each of the sidewalls69B. A left first contact portion69C protrudes from the left sidewall69B outward (to the left) while a right first contact portion69C protrudes from the right sidewall69B outward (to the right). Each first contact portion69C is disposed at a position in an upper end portion of the corresponding sidewall69B, opposite, separately, to an obliquely-rear-and-upper side of the photoconductor drum61(i.e., on the fixing-unit side that is one of opposite sides with respect to the photoconductor61on which the fixing unit8is disposed). Provided at an upper end of each sidewall69B is a second contact portion69D protruding upward. The second contact portion69D is disposed in a position corresponding to the first contact portion69C in the front-rear direction.

The housing2includes left and right side frames25, and a first housing-side contact portion25A as an example of a second engageable portion and a second housing-side contact portion25B are provided at each of the side frames25. The first housing-side contact portion25A is contactable with a lower end of the corresponding first contact portion69C. The second housing-side contact portion25B is contactable with an upper end of the corresponding second contact portion69D. A left first housing-side contact portion25A protrudes from the left side frame25inward (to the right) while a right first housing-side contact portion25A protrudes from the right side frame25inward (to the left). A left second housing-side contact portion25B protrudes from the left side frame25inward (to the right) while a right second housing-side contact portion25B protrudes from the right side frame25inward (to the left).

A guide portion25C is provided at each side frame25. The guide portion25C is configured to guide installation and removal of the photoconductor cartridge6. The guide portion25C is configured as a groove engageable with a drum shaft61A of the photoconductor drum61and shaped to extend in the front-rear direction. The side frame25is also provided with a spring25E to lock the drum shaft61A.

The photoconductor cartridge6includes a first chute64as an example of a chute configured to guide a sheet33passed through between the photoconductor drum61and the transfer roller63toward the fixing unit8. The first chute64extends, from a position in the photoconductor frame69corresponding to a transfer position P1in which the photoconductor drum61and the transfer roller63are in contact with each other, toward the fixing unit8(downstream in a sheet33conveyance direction).

As shown inFIG. 1, the aforementioned rear opening22A is disposed right behind the first chute64. In other words, the rear opening22A is disposed behind the first chute64opposite to a path of a sheet being conveyed toward the fixing unit8(i.e., the rear opening22A and the path of the sheet being conveyed toward the fixing unit8are disposed on opposite sides with the first chute64between).

As shown inFIGS. 2 and 3, the first chute64includes a plurality of first chute main units66arranged laterally, and a first connecting portion65extending laterally and connecting the plurality of first chute main units66.

The first chute main units66are units each shaped like a rib protruding from the front surface and the rear surface of the first connecting portion65and arranged along the path of a sheet33being conveyed from the transfer position P1toward the fixing unit8(in a sheet conveyance direction). Each of the first chute main units66has a front-side surface66A that is an end face of a portion protruding from the front surface of the first connecting portion65. The front-side surface66A is contactable with a sheet33being conveyed from the transfer position P1.

The front-side surface66A is an example of an inwardly curved surface, and is recessed rearward. The front-side surface66A is so arranged that the inwardly curved surface faces the path of a sheet33being conveyed from the transfer position P1toward the fixing unit8.

Each of the first chute main units66includes an upper end portion66B protruding from an upper end of the first connecting portion65. Upper end portions66B and the upper end of the first connecting portion65of the first chute64are shaped like a comb, as viewed from the rear; thus, the first chute64has a comb-tooth shape formed in a distal (upper) end portion thereof (at a to fixing-side end thereof facing to the fixing unit8, or at a downstream end facing downstream in the sheet conveyance direction). These upper end portions66B and the upper end of the first connecting portion65form a first comb-like portion configured by way of example.

The fixing unit8includes a fixing unit frame83by which the heating roller81and the pressure roller82described above are supported. The fixing unit frame83is provided with a second chute84. The second chute84extends from a lower end portion of the fixing unit frame83toward the photoconductor cartridge6.

The second chute84is configured to further guide a sheet33guided by the first chute64, to a fixing position P2in which the heating roller81and the pressure roller82are in contact with each other. The second chute84includes a plurality of second chute main units86arranged laterally, and a second connecting portion85extending laterally and connecting the plurality of second chute main units86.

The second chute main units86are units each shaped like a rib protruding from the front surface and the rear surface of the second connecting portion85and arranged along the path of a sheet33being conveyed from the transfer position P1toward the fixing unit8(in the sheet conveyance direction). Each of the second chute main units86has a front-side surface86A that is an end face of a portion protruding from the front surface of the second connecting portion85. The front-side surface86A is contactable with a sheet33being conveyed toward the fixing position P2.

Each of the second chute main units86includes a lower end portion86B protruding from a lower end of the second connecting portion85. Lower end portions86B and the lower end of the second connecting portion85of the second chute84are shaped like a comb, as viewed from the rear; thus, the second chute84has a comb-tooth shape formed in a distal (lower) end portion thereof (at a photoconductor-side end facing the photoconductor cartridge6). These lower end portions86B and the lower end of the second connecting portion85form a second comb-like portion configured by way of example.

As shown inFIG. 2, the upper end portions66B of the first chute main units66and the lower end portions86B of the second chute main units86are overlap each other as viewed in a lateral direction (in an axial direction of the photoconductor drum61). In other words, the first chute64and the second chute84are arranged so as not to make a gap in the sheet conveyance direction. As shown inFIG. 3, the upper end portions66B of the first chute main units66and the lower end portions86B of the second chute main units86are arranged in positions shifted from each other.

The upper end portions66B of the first chute main units66are located frontwardly of (i.e., closer to the sheet33being conveyed than) the lower end portions86B of the second chute main units86. This may serve to prevent the sheet33being conveyed from the transfer position P1, from colliding with the lower ends of the second chute main units86.

Operation of the laser printer1configured as described above will now be described.

As shown inFIG. 2, a sheet33passed through the transfer position P1is conveyed toward the fixing unit8. The sheet33is guided by the first chute64, and thus conveyed stably toward the fixing unit8. The sheet33is conveyed while smoothly sliding in contact with the curved front-side surface66A of the first chute64.

As no gap is left between the first chute64and the second chute84in the sheet conveyance direction, the sheet33is smoothly conveyed from the first chute64to the second chute84. The sheet is guided by the second chute84and conveyed toward the fixing position P2. Accordingly, the sheet33is stably conveyed from the transfer position P1toward the fixing position P2.

On the other hand, when the development cartridge7is removed from the housing2, the front cover21is swung open and the development cartridge7is removed through the front opening21A. In this operation, the development cartridge7is removed from a display-unit side of the housing2on which the display unit23is provided to display an operation status of the laser printer7for a user, that is, from a front side (i.e., from a user side), the replacement of the development cartridge7that may be required more frequently than the replacement of the photoconductor cartridge6can be carried out more easily.

When the photoconductor cartridge6is removed from the housing2, the rear cover22is swung open and the photoconductor cartridge6is removed through the rear opening22A. In this operation, the drum shaft61A is moved straight rearward along the guide portion25C until the photoconductor cartridge6is removed out of the housing2. Since the first chute main units66and the second chute main units86are arranged alternately in positions laterally shifted from each other, the photoconductor cartridge6can be removed smoothly without interference with the second chute84. Since the handle69A is configured to extend rearward, the user can easily grasp and manipulate the photoconductor cartridge6inside the housing2.

Since the LED unit4is opposite to the front side of the peripheral surface of the photoconductor drum61, the light-emitting elements of the LED unit4that face rearward can be easily accessed for cleaning once the photoconductor cartridge6is removed through the rear opening22A.

In this configuration described above, the development cartridge7and the photoconductor cartridge6are removed from different sides, respectively, each cartridge7,6can be removed from the housing2smoothly without interfering with other components inside the housing2, more smoothly in comparison with an alternative configuration in which the development cartridge6and the photoconductor cartridge are removed from one and the same side. Further, the photoconductor cartridge6is removed through the rear opening22A, the photoconductor cartridge can be removed smoothly without interfering with the LED unit4that is disposed at the front side of the photoconductor drum61(i.e., behind the photoconductor drum61opposite to the rear opening22A).

When the development cartridge7and the photoconductor cartridge6are installed in the housing2, the development cartridge7is installed through the front opening21A and the photoconductor cartridge6is installed through the rear opening22A.

In this operation, the drum shaft61A of the photoconductor cartridge6is moved frontward along the guide portion25C, until the drum shaft61A is locked by the spring25E at the frontmost position of the guide portion25C. Then, the first contact portion69C of the photoconductor cartridge6is engaged with the first housing-side contact portion25A of the side frame25. In this way, the photoconductor cartridge6is installed in the housing2. Accordingly, the vertical position of the photoconductor cartridge6is determined, so that the first chute64is accurately positioned relative to the fixing position P2of the fixing unit8.

With this configuration, even when the photoconductor cartridge6installed in the housing2receives a rotational force produced in a counterclockwise direction inFIG. 2about the drum shaft61A according to the rotation of the photoconductor drum61, the second contact portion69D of the photoconductor cartridge6getting in contact with the second housing-side contact portion25B of the side frame25serves to restrict the rotation of the photoconductor cartridge6about the drum shaft61A, making the photoconductor cartridge6stable in place.

In this installation operation, as well as the removal operation, the development cartridge7and the photoconductor cartridge6can be installed smoothly in the housing2, respectively, without interfering with any other components inside the housing2.

Advantages of the configuration described above are as follows:

Since the accurate positioning of the first chute64relative to the photoconductor drum61and the transfer roller65can be established with increased ease, a sheet33passed through between the photoconductor drum61and the transfer roller63can be conveyed stably toward the fixing device8.

Since the photoconductor cartridge6can be removed through the rear opening22A provided right behind the first chute64(behind the first chute64opposite to the path of a sheet33being conveyed toward the fixing unit8), a user can remove the photoconductor cartridge6from the housing2with increased ease.

Since the first chute64has an inwardly curved front-side surface66A facing the path of a sheet33being conveyed toward the fixing unit8, the sheet33with a toner image formed thereon can be guided smoothly while letting its back side slide on the front-side surface66A.

Since the first chute64and the second chute84are provided, the sheet33can be guided properly from the transfer position P1toward the fixing position P2.

Since no gap is left in the sheet conveyance direction between the first chute64and the second chute84, the sheet33can be conveyed smoothly.

Since the fixing unit8is disposed above the photoconductor cartridge6, the heat produced in the fixing unit8is less likely to affect the photoconductor drum61. Similarly, since the development roller71is disposed behind the photoconductor drum61opposite to the fixing unit8, the development roller71is less likely to receive an adverse effect of the heat produced in the fixing unit8.

Since the charger62is included in the photoconductor cartridge6and supported by the photoconductor frame69, the charger62can be easily handled for replacement or cleaning outside the housing2by a user taking out the photoconductor cartridge6.

Since the vertical position of the photoconductor cartridge6as installed in the housing2can be determined appropriately by the first contact portion69C of the photoconductor cartridge6engaged with the first housing-side contact portion25A of the side frame25, the first chute64and the fixing unit8are accurately positioned relative to each other.

Since the transfer unit63is supported by the photoconductor cartridge69, the accuracy of the transfer process can be improved in comparison with an alternative configuration in which a transfer roller (transfer unit) is provided in a housing of the printer.

Since the transfer roller63is so disposed as to overlap the handle69A as viewed from the rear side, the transfer roller63can be protected from the handle69A. Furthermore, since the handle69A of the photoconductor cartridge6is disposed behind the transfer roller63opposite to the photoconductor drum61(i.e., the handle69A and the photoconductor drum61are disposed on opposite sides with the transfer roller63between), the photoconductor cartridge6can be removed easily through the rear opening22A by the use of the handle69A.

Installation and removal of the development cartridge7are carried out at the front side, that is, through the front opening21A at the same side as the side on which the display unit23faces a user. Therefore, the installation and removal of the development cartridge7which are required more frequently than those of the photoconductor cartridge6can be made easy.

Since the LED unit4is disposed at the front side of the photoconductor drum61, cleaning of the LED unit4can be conducted easily when the photoconductor cartridge6is removed through the rear opening22A. Moreover, interference of the photoconductor cartridge6with the LED unit4upon installation and removal of the photoconductor cartridge6is less likely to occur in comparison with an alternative configuration in which the photoconductor cartridge and the development cartridge are removed and installed through the front opening.

It is to be understood that various modifications and changes may be made to the above-described specific embodiment as will be described below by way of example.

In the above description, the guide portion25C is illustrated as extending in the front-rear direction, but an alternative configuration may be feasible; for example, as shown inFIG. 4, a guide portion25D may be shaped to deviate toward the fixing unit8in a direction from the outside of the housing2into the housing2.

With this alternative configuration, since the photoconductor6is moved away from the fixing unit8according as the photoconductor cartridge6is moved toward the outside of the housing2, interference of the first chute64with the fixing unit8which would occur when the photoconductor cartridge6is removed and installed can be prevented.

Since the charger62is disposed over the photoconductor drum61(i.e., on a fixing-unit side that is one of opposite sides with respect to the photoconductor drum61on which the fixing unit8is disposed) in the photoconductor cartridge6, interference of the charger62with the fixing unit8would likely occur when the photoconductor cartridge6is removed and installed; however, this alternative configuration illustrated inFIG. 4is configured such that the guide portion25D causes the photoconductor cartridge6to be moved away from the fixing unit8when the photoconductor cartridge6is removed, and thus interference of the charge62with the fixing unit8which would occur when the photoconductor cartridge6is removed and installed can be suppressed.

Also, in this configuration, the first chute64is disposed in such a position that the tangent to the photoconductor drum61at the transfer position P1intersects the first chute64. Accordingly, the sheet33passed through the transfer position P1becomes likely to get in contact with the first chute64, so that the guiding of the sheet33by the first chute64toward the fixing unit8can be facilitated.

In the above description, the curved first chute64is illustrated by way of example; however, the curved surface is not requisite. The first chute may not be curved.

In the above description, the first chute64and the second chute84illustrated by way of example are both configured to include comb-like portions (shaped like combs) at their distal ends; however, such comb-like shape in the distal-end portion is not requisite. The comb-like shape may not be provided in either or both of the first and second chutes64,84.

In the above description, the first contact portion69C as an example of the first engageable portion is provided by way of example; however, this is not requisite. Such an engageable portion may not be provided.

In the above description, the transfer roller63is illustrated, by way of example, as being supported by the photoconductor frame69; however, the transfer roller63may be supported by any other portion, for example, by the rear cover22.

In the above description, the development cartridge7is adopted as an example of a developer cartridge; however, a toner cartridge storing toner can be adopted as an alternative of the development cartridge7. In this configuration, the development roller and the supply roller may be provided in the photoconductor cartridge.

In the above description, a monochrome laser printer1is illustrated as an example of an image forming apparatus, but a color printer or a multifunction peripheral, or other type of image forming apparatus may be configured as described herein.