JP2024106187A - Process unit and image forming apparatus - Google Patents

Abstract

To provide a process unit that can prevent attachment of starting powder applied to a photoreceptor drum to an electrifying member.SOLUTION: A process unit 60 comprises: a process frame 62 that removably supports a photoreceptor drum 36; and a support member (74) that supports an electrifying member (70). The support member is provided on the process frame movably to a first position where the electrifying member is in contact with the photoreceptor drum and a second position where the electrifying member is separated from the photoreceptor drum. The support member is provided with a regulation part (86) that regulates a movement in a removal direction of the photoreceptor drum when the support member is at the first position and cancels the regulation on the movement of the photoreceptor drum when the support member is at the second position.SELECTED DRAWING: Figure 7

Description

This disclosure relates to a process unit and an image forming apparatus, and in particular to a process unit and an image forming apparatus that include, for example, a photosensitive drum and a charging member that charges the photosensitive drum.

One example of a conventional process unit is disclosed in Patent Document 1. The process unit in Patent Document 1 uses a frame to unitize the photosensitive drum and charging member (charger), and is detachably mounted on the image forming apparatus. In the process unit, a locking claw is formed on the support member that supports the charging member, and a first locking portion is formed on the frame, and these engage with each other to prevent the support member from coming off the frame. The locking claw is also used to hold the charging member at a distance from the photosensitive drum when the photosensitive drum is attached to the frame.

JP 2015-121683 A

The surface of the photosensitive drum is coated with starting powder (such as zinc stearate) as a lubricant to prevent the cleaning blade from reversing at the beginning. For this reason, when the photosensitive drum is attached to the frame of the process unit, if the photosensitive drum and the charging member are not separated, the starting powder may adhere to the charging member, causing charging failure. In the technology of Patent Document 1, the support member that supports the charging member has a locking claw, and when the photosensitive drum is attached to the process unit with the charging member attached, the charging member can be separated (retracted) from the photosensitive drum.

However, with the technology of Patent Document 1, it is possible to attach the photosensitive drum to the process unit even when the charging member is not in the separated position. This means that there is a possibility that a service person (operator) will make an operational error by forgetting to retract the charging member. If such an operational error occurs, not only will the service person have to manually clean the charging member, but if the service person does not notice the operational error, there is also the possibility that the market will complain about poor image quality, which could develop into a major problem.

Therefore, the primary objective of this disclosure is to provide a novel process unit and image forming apparatus.

Another object of this disclosure is to provide a process unit and an image forming apparatus that can prevent starting powder applied to a photosensitive drum from adhering to a charging member when the photosensitive drum is replaced.

The first disclosure is a process unit including a photosensitive drum and a charging member for charging the photosensitive drum, the process unit including a process frame for detachably supporting the photosensitive drum, an attachment/detachment opening for the photosensitive drum formed in the process frame, a support member provided on the process frame for supporting the charging member and movable between a first position where the charging member abuts against the photosensitive drum and a second position where the charging member is spaced apart from the photosensitive drum, and a regulating portion provided on the support member that protrudes into the attachment/detachment opening when the support member is in the first position to regulate the movement of the photosensitive drum in the attachment/detachment direction and retracts from the attachment/detachment opening when the support member is in the second position to release the regulation of the movement of the photosensitive drum.

According to the first disclosure, the support member that supports the charging member has a regulating portion that regulates the movement of the photosensitive drum, and the photosensitive drum cannot be attached or detached unless the support member moves to the second position where the charging member is separated (retracted) from the photosensitive drum. Therefore, it is possible to prevent the operational error of forgetting to retract the charging member, and it is possible to reliably prevent the starting powder applied to the photosensitive drum from adhering to the charging member.

The second disclosure is dependent on the first disclosure, and the support member includes a bearing member that rotatably supports the charging member.

The third disclosure is dependent on the first or second disclosure, and the photosensitive drum includes a drum body and shaft members provided at both ends of the drum body, and the regulating portion regulates the movement of the photosensitive drum by contacting the shaft members.

The fourth disclosure is dependent on the first or second disclosure and includes a biasing member provided on the support member that biases the charging member together with the support member toward the photosensitive drum, a latched portion provided on the support member, and a latching portion provided on the process frame that holds the support member in the second position by engaging with the latched portion.

The fifth disclosure is an image forming apparatus having a process unit according to the first disclosure.

This disclosure makes it possible to prevent the operational error of forgetting to move the charging member out of the way, and therefore to reliably prevent the starting powder applied to the photosensitive drum from adhering to the charging member.

The above and other objects, features and advantages of this disclosure will become more apparent from the detailed description of the embodiments described below with reference to the drawings.

1 is a schematic cross-sectional view showing an internal structure of an image forming apparatus including a process unit according to an embodiment of the present disclosure. FIG. 2 is a perspective view showing a process unit. FIG. 2 is a left side view showing the process unit. 4 is a cross-sectional view showing a cross section of the process unit taken along line IV-IV in FIG. 3. 4 is a cross-sectional view showing a cross section of the process unit taken along line V-V in FIG. 3. FIG. 2 is a perspective view showing a bearing member provided in the process unit. 4 is a schematic cross-sectional view showing the process unit in a state where the bearing member is in a first position. FIG. 4 is a schematic cross-sectional view showing the process unit in a state where the bearing member is in a second position. FIG.

[Example]
1 and 2, a process unit 60 according to an embodiment of the present disclosure is used in an image forming apparatus 10 that forms a multi-color or monochrome image on paper (recording medium) by electrophotography. As will be described in detail later, the process unit 60 is an integrated unit including a photoconductor drum 36, a cleaning device 38, a charging device 40, etc., and is detachably provided in the apparatus body 12 of the image forming apparatus 10.

First, the basic configuration of the image forming device 10 will be briefly described. Note that in this disclosure, the front side (front) is defined as the surface facing the position of the user operating the image forming device 10, i.e., the surface on which the operation panel is provided, and the front-to-rear direction (depth direction) of the image forming device 10 and its components are defined. In addition, the left-to-right direction (horizontal direction) of the image forming device 10 and its components are defined based on the state when the image forming device 10 is viewed from the front.

As shown in FIG. 1, the image forming device 10 is a multifunction peripheral (MFP) that has functions such as copying, printing, scanning, and facsimile, and forms multicolor or monochrome images on paper (recording medium) using an electrophotographic method. The image forming device 10 includes a device main body 12 that includes an image forming unit 30 and the like, and an image reading device 14 located above the device main body 12.

The image reading device 14 has a document placement platform 16 made of a transparent material. A document pressing cover 18 is attached above the document placement platform 16 via a hinge or the like so that it can be opened and closed freely. This document pressing cover 18 is provided with an ADF (automatic document feeder) 24 that automatically feeds documents placed on a document placement tray 20 one by one to an image reading position 22. Although not shown, an operation panel is provided on the front side of the document placement platform 16 to accept input operations such as printing instructions from the user. This operation panel is appropriately provided with a touch panel display and operation buttons, etc.

The image reading device 14 also has a built-in image reading unit 26 that includes a light source, multiple mirrors, an imaging lens, and a line sensor. The image reading unit 26 exposes the document surface to the light source, and guides the light reflected from the document surface to the imaging lens using multiple mirrors. The imaging lens then focuses the reflected light on the light receiving element of the line sensor. The line sensor detects the luminance and chromaticity of the reflected light focused on the light receiving element, and generates image data based on the image of the document surface. A CCD (Charge Coupled Device) or a CIS (Contact Image Sensor) is used as the line sensor.

The device body 12 includes a control unit (not shown) including a CPU, memory, etc., and an image forming unit 30. The control unit transmits control signals to each part of the image forming device 10 in response to input operations on an operation panel, etc., and causes the image forming device 10 to perform various operations.

The image forming section 30 includes an exposure unit 32, a developing unit 34, a photoconductor drum 36, a cleaning device 38, a charging device 40, an intermediate transfer belt unit 42, a transfer roller 44, and a fixing unit 46, and forms an image on paper transported from a paper feed tray 48, etc., and discharges the paper with the image formed on it to a paper discharge tray 50. As image data for forming an image on the paper, image data read by the image reading section 26 or image data sent from an external computer, etc., is used.

The image data handled by the image forming device 10 corresponds to color images of four colors: black (K), cyan (C), magenta (M), and yellow (Y). For this reason, four of each of the developing units 34, photoconductor drums 36, cleaning devices 38, and charging devices 40 are provided to form four types of latent images corresponding to each color, and these constitute four image stations.

The photosensitive drum 36 is an image carrier having a drum body 36a (see FIG. 2) with a photosensitive layer formed on its surface, and is provided so as to extend in the front-rear direction. The charging device 40 has a charging roller 70 and a cleaning roller 72 (see FIG. 2), etc., and charges the surface of the photosensitive drum 36 (specifically, the drum body 36a) to a predetermined potential. The cleaning device 38 removes and collects toner remaining on the surface of the photosensitive drum 36 after development and image transfer. The photosensitive drum 36, cleaning device 38, and charging device 40 are integrated, and together they constitute the process unit 60. The specific configuration of the process unit 60 will be described later.

The exposure unit 32 is configured as a laser scanning unit (LSU) equipped with a laser diode, a polygon mirror, etc., and exposes the charged surface of the photoconductor drum 36 to light, thereby forming an electrostatic latent image on the surface of the photoconductor drum 36 according to the image data. The development unit 34 supplies toner to the surface of the photoconductor drum 36, and visualizes the electrostatic latent image formed on the surface of the photoconductor drum 36 with the toner (forming a toner image).

The intermediate transfer belt unit 42 includes an intermediate transfer belt 52, a drive roller, a driven roller, and four intermediate transfer rollers 54. The intermediate transfer belt 52 is provided so as to contact each photosensitive drum 36, and the intermediate transfer rollers 54 are used to transfer the toner images of each color formed on each photosensitive drum 36 to the intermediate transfer belt 52 in a sequential, overlapping manner, thereby forming a multi-color toner image on the intermediate transfer belt 52. In addition, a transfer roller 44 is disposed near the drive roller, and the toner image formed on the intermediate transfer belt 52 is transferred to the paper by the paper passing through the nip area between the intermediate transfer belt 52 and the transfer roller 44.

The fixing unit 46 includes a heat roller and a pressure roller, and is disposed above the transfer roller 44. The heat roller is set to a predetermined fixing temperature, and as the paper passes through the nip area between the heat roller and the pressure roller, the toner image transferred to the paper is melted, mixed, and pressed against the paper, thereby thermally fixing the toner image to the paper.

In addition, a first paper transport path L1 is formed within the device body 12 to send paper from the paper feed tray 48, etc., through the registration rollers 56, the transfer roller 44, and the fixing unit 46 to the paper output tray 50. In addition, when performing double-sided printing on the paper, a second paper transport path L2 is formed to return the paper after single-sided printing is completed and the paper has passed through the fixing unit 46 to the first paper transport path L1 upstream of the transfer roller 44 in the paper transport direction. A plurality of transport rollers 58 are appropriately provided on the first paper transport path L1 and the second paper transport path L2 to provide auxiliary propulsion force to the paper.

Next, the configuration of the process unit 60 will be described. As shown in Figures 2 to 5, the process unit 60 includes a photoconductor drum 36, a cleaning device 38, and a charging device 40, which are held together in a predetermined arrangement by a process frame 62. The process unit 60 is detachable from the front side of the device body 12, and is attached to or detached from the device body 12 by sliding it in the depth direction (front-to-back direction) of the device body 12.

The photosensitive drum 36 comprises a drum body 36a in which a photosensitive layer is formed on the surface of a cylindrical base body having electrical conductivity. Axle members 36b are fitted and fixedly attached to both ends of the drum body 36a. The shaft members 36b have a drum shaft 36c that is provided to pass through the center. Both ends of the drum shaft 36c are rotatably supported by bearings provided in the process frame 62. Although not shown, a drive motor is connected to the rear end of the drum shaft 36c via a coupling portion and a gear train. The drum body 36a rotates with the rotation of the drum shaft 36c. In other words, the photosensitive drum 36 is rotatably supported around the drum shaft 36c by the process frame 62, and rotates by the driving force transmitted from the drive motor.

The cleaning device 38 includes a cleaning blade and a transport member. The cleaning device 38 uses the cleaning blade to remove foreign matter such as toner remaining on the surface of the photoconductor drum 36, and sends the removed foreign matter to a waste toner box using the transport member.

The charging device 40 includes a charging roller 70 and a cleaning roller 72, and is disposed below the photosensitive drum 36. The charging roller 70 is an example of a charging member that charges the photosensitive drum 36, and is disposed parallel to the photosensitive drum 36. The charging roller 70 charges the surface of the photosensitive drum 36 to a predetermined potential while rotating in accordance with the rotation of the photosensitive drum 36, with its surface (outer surface) in contact with the surface of the photosensitive drum 36 at a predetermined pressure. The cleaning roller 72 is disposed in a circumferential position opposite the photosensitive drum 36 so as to come into contact with the surface of the charging roller 70, and removes foreign matter such as toner adhering to the outer peripheral surface of the charging roller 70.

In addition, both ends of the shaft of the charging roller 70 are rotatably supported by bearing members 74 (an example of a support member). The bearing members 74 are attached to the process frame 62 in a state in which they can move in the radial direction of the photosensitive drum 36, and can move linearly between a first position where the charging roller 70 abuts against the photosensitive drum 36 and a second position where the charging roller 70 is separated (retracted) from the photosensitive drum 36. That is, the charging roller 70 supported by the bearing members 74 is movable (separable) in the radial direction of the photosensitive drum 36, and is provided so as to be switchable between a separated state where it is separated from the photosensitive drum 36 and a contact state where it abuts against the photosensitive drum 36. In this embodiment, the cleaning roller 72 is also rotatably supported by the bearing members 74 together with the charging roller 70. The configuration of the bearing members 74 will be described later.

A biasing member 76 such as a compression coil spring is provided at the lower end of the bearing member 74 (the end opposite the photosensitive drum 36). This biasing member 76 is a member for abutting the charging roller 70 against the photosensitive drum 36 with a predetermined pressure, and biases the charging roller 70 toward the photosensitive drum 36 together with the bearing member 74.

Furthermore, the bearing member 74 has a locking claw 84 (an example of a locked portion). By engaging this locking claw 84 with the locking portion 62a provided on the process frame 62, the bearing member 74 can be held in a second position where the charging roller 70 is separated from the photosensitive drum 36 (see FIG. 8). Therefore, by keeping the photosensitive drum 36 and the charging roller 70 separated when left unused for a long period of time or during transportation, damage to the photosensitive drum 36 and the charging roller 70 due to vibration and long-term pressure contact can be prevented.

Furthermore, at the upper part of the process frame 62, an attachment/detachment guide 78 having an attachment/detachment opening 78a opening toward the left side is provided at a position corresponding to both ends of the photosensitive drum 36 (specifically, each of the shaft members 36b). The photosensitive drum 36 can be attached and detached from the process frame 62 in the left-right direction (i.e., in a direction perpendicular to the axial direction of the photosensitive drum 36) through this attachment/detachment opening 78a. In addition, at the lower part of the process frame 62, a locking portion 62a and a release member insertion hole 62b are formed at a position corresponding to the locking claw 84 of the bearing member 74 (see FIG. 8). The locking portion 62a protrudes from the inner surface of the process frame 62 toward the bearing member 74, and holds the bearing member 74 in the second position by engaging with the locking claw 84. The release member insertion hole 62b is a hole for inserting a rod-shaped release member to release the engagement between the locking portion 62a and the locking claw 84.

In such a process unit 60, when replacing the photosensitive drum 36, it is necessary to prevent starting powder such as zinc stearate applied to the surface of the photosensitive drum 36 from adhering to the charging roller 70. For this reason, in this embodiment, a regulating claw 86 (an example of a regulating portion) that regulates the attachment and detachment of the photosensitive drum 36 is provided on the bearing member 74, and the photosensitive drum 36 can be attached and detached only when the bearing member 74 is in the second position, thereby reliably preventing starting powder from adhering to the charging roller 70. This will be explained in detail below.

As shown in FIG. 6, the bearing member 74 includes a first bearing portion 80, a second bearing portion 82, a locking claw 84, and a regulating claw 86, which are integrally molded from synthetic resin. Note that FIG. 6 shows the bearing member 74 supporting the front end of the charging roller 70 as viewed from above on the rear side, but it should be noted that the shape of the bearing member 74 supporting the rear end of the charging roller 70 is reversed from the front end side of the bearing member 74.

The first bearing portion 80 is formed as a curved plate having an arc-shaped cross section, and its inner surface supports the end of the shaft of the charging roller 70. The second bearing portion 82 is formed as a curved plate having an arc-shaped cross section below the first bearing portion 80, and its inner surface supports the end of the shaft of the cleaning roller 72.

Furthermore, the locking claw 84 is formed on the right side of the first bearing portion 80. As described above, the locking claw 84 is used to hold the bearing member 74 at the second position where the charging roller 70 is separated from the photosensitive drum 36. The locking claw 84 has a support piece 84a formed in an L-shape and a locking piece 84b with a generally triangular cross section formed at the tip of the support piece 84a. Since the locking claw 84 has the support piece 84a formed in an L-shape, it has appropriate elasticity to bend in the left-right direction. Therefore, when the locking claw 84 engages or disengages with the locking portion 62a of the process frame 62, the locking claw 84 is appropriately elastically deformed to prevent damage.

A restricting claw 86 is provided on the upper side of the first bearing portion 80 at an axial position corresponding to the shaft member 36b of the photosensitive drum 36 so as to protrude diagonally upward to the left. The restricting claw 86 is a part that restricts the movement of the photosensitive drum 36 in the attachment/detachment direction, and one side surface 86a (the side surface on the photosensitive drum 36 side) is a curved surface that follows the outer surface of the shaft member 36b of the photosensitive drum 36. The restricting claw 86 is displaced in a direction that protrudes and retracts from the attachment/detachment opening 78a in accordance with the displacement of the bearing member 74. That is, when the bearing member 74 is in the first position, the restricting claw 86 is in a protruding state that protrudes into the attachment/detachment opening 78a of the attachment/detachment guide 78 provided in the process frame 62. At this time, the protruding length of the restricting claw 86 protruding into the attachment/detachment opening 78a is set to, for example, 2 mm to 10 mm. In addition, a gap of, for example, about 0.5 mm is formed between one side surface 86a of the regulating claw 86 and the outer surface of the shaft member 36b of the photosensitive drum 36. On the other hand, when the bearing member 74 is in the second position, the regulating claw 86 is in a retracted state where it is retracted from the attachment/detachment opening 78a of the attachment/detachment guide 78.

In the process unit 60 equipped with the bearing member 74 having such a restricting claw 86, as shown in FIG. 7, when the bearing member 74 is in the first position (i.e., when the charging roller 70 is in a position where it abuts against the photosensitive drum 36), the restricting claw 86 protrudes into the mounting/removal opening 78a of the mounting/removal guide 78 and blocks a part of the mounting/removal opening 78a. This restricts the mounting/removal (replacement) of the photosensitive drum 36. That is, even if an attempt is made to attach the photosensitive drum 36 when the bearing member 74 is in the first position, the restricting claw 86 abuts against the shaft member 36b of the photosensitive drum 36, restricting the movement of the photosensitive drum 36, and the photosensitive drum 36 cannot be attached to the process frame 62. Similarly, even if an attempt is made to remove the photosensitive drum 36 when the bearing member 74 is in the first position, the photosensitive drum 36 cannot be removed from the process frame 62.

On the other hand, as shown in FIG. 8, when attaching or detaching the photosensitive drum 36, the bearing member 74 is pressed down and the locking claw 84 of the bearing member 74 is engaged with the locking portion 62a of the process frame 62 to hold the bearing member 74 in the second position. When the bearing member 74 is in the second position (i.e., when the charging roller 70 is in a position separated from the photosensitive drum 36), the restricting claw 86 retreats from the attachment/detachment opening 78a of the attachment/detachment guide 78, and the attachment/detachment opening 78a is opened. In other words, the movement restriction of the photosensitive drum 36 is released, so that the photosensitive drum 36 can be removed from the process frame 62 and a new photosensitive drum 36 can be attached to the process frame 62. By attaching the photosensitive drum 36 when the charging roller 70 is in a position separated (retracted) from the photosensitive drum 36, the starting powder applied to the surface of the photosensitive drum 36 is prevented from adhering to the charging roller 70. This prevents charging failures from occurring.

After the photoconductor drum 36 is attached to the process unit 60 (process frame 62), the photoconductor drum 36 is rotated while the photoconductor drum 36 and the charging roller 70 are separated from each other. This allows the starting powder on the surface of the photoconductor drum 36 to be removed by the cleaning blade of the cleaning device 38. Thereafter, a release member is inserted through the release member insertion hole 62b to release the engagement between the locking portion 62a and the locking claw 84, and the bearing member 74 is returned to the first position to bring the photoconductor drum 36 and the charging roller 70 into contact with each other.

As described above, according to this embodiment, the bearing member 74 has a restricting claw 86 that restricts movement of the photosensitive drum 36 in the attachment/detachment direction, and the photosensitive drum 36 cannot be attached or detached unless the bearing member 74 is moved to the second position where the charging roller 70 is separated (retracted) from the photosensitive drum 36. In other words, with the simple configuration of providing the restricting claw 86 on the bearing member 74, it is possible to prevent the operational error of forgetting to retract the charging roller 70 when attaching the photosensitive drum 36, and it is possible to reliably prevent the starting powder applied to the photosensitive drum 36 from adhering to the charging roller 70.

In the above embodiment, the charging device including the bearing member and the charging roller is directly attached to the process frame, but the bearing member and the charging roller can be integrated with the charging frame, and this integrated charging device (charging unit) can be detachably attached to the process frame. In addition, when the charging device is integrated as a unit, a regulating portion (regulating claw) that regulates the movement of the photosensitive drum 36 in the attachment/detachment direction can be provided on the charging frame.

In addition, in the above embodiment, a charging roller is used as the charging member, but a brush-type charging member (charging brush) can also be used. In this case, it is preferable to form a regulating portion on the support member for the charging brush.

In addition, in the above embodiment, a multifunction machine combining a copier, a facsimile, a printer, etc. is exemplified as the image forming device, but the image forming device may be any one of a copier, a facsimile, a printer, etc., or a multifunction machine combining at least two of these. The image forming device may also be a monochrome machine.

Note that the specific numerical values and part shapes listed above are merely examples and can be changed as necessary depending on the product specifications, etc.

REFERENCE SIGNS LIST 10 image forming apparatus 12 apparatus main body 30 image forming section 36 photosensitive drum 38 cleaning device 40 charging device 60 process unit 62 process frame 62a engaging portion 70 charging roller (charging member)
74 ... Bearing member (support member)
84...Latching claw (locked part)
86 ... Regulating claw (regulating part)

Claims (5)

A process unit including a photosensitive drum and a charging member for charging the photosensitive drum,
a process frame that detachably supports the photosensitive drum;
an attachment/detachment opening for the photosensitive drum formed in the process frame;
a support member provided on the process frame to support the charging member and to be movable between a first position where the charging member contacts the photosensitive drum and a second position where the charging member is spaced from the photosensitive drum; and a regulating portion provided on the support member, which protrudes into the attachment/detachment opening when the support member is in the first position to regulate movement of the photosensitive drum in the attachment/detachment direction, and which retracts from the attachment/detachment opening when the support member is in the second position to release the regulation of movement of the photosensitive drum. The process unit according to claim 1, wherein the support member includes a bearing member that rotatably supports the charging member. The photosensitive drum includes a drum body and a shaft member provided at both ends of the drum body,
3. The process unit according to claim 1, wherein the regulating portion regulates the movement of the photosensitive drum by contacting the shaft member. a biasing member provided on the supporting member and biasing the charging member toward the photosensitive drum together with the supporting member;
3 . The process unit according to claim 1 , further comprising: a latched portion provided on the support member; and a latching portion provided on the process frame, which holds the support member at the second position by engaging with the latched portion. An image forming apparatus equipped with the process unit according to claim 1.

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