JP2015102754A - Electrifying device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying device and an image formation device, capable of suppressing a degradation in performance of cleaning an electrifying member.SOLUTION: A cleaning member 72 is configured by spirally winding a cleaning material 76 on a core material 74. Since the outside diameter of the cleaning member 72 partially varies, the cleaning member 72 which rotates following a rotating electrification roll 70 may shift (oscillate) vertically. Here, the tolerable amount that tolerates movement from a contact state to above the core material 74 is set to be equal to or less than the difference between the height of an end part 76A of the cleaning material 76 and the height of a center part 76B. Thus, even when the core material 74 moves upward from the contact state, the end part 76A of the cleaning material 76 is in contact with the electrifying roll 70. Thus, performance of cleaning the electrifying roll 70 is suppressed from being degraded.

Description

  The present invention relates to a charging device and an image forming apparatus.

  In Patent Document 1, a shaft of a cleaning roll for cleaning the charging roll is rotatably supported, and is guided so as to be movable in different directions with respect to a linear direction passing through the rotation center of the charging roll and the rotation center of the cleaning roll. A support member is described.

JP 2007-333804 A

  The subject of this invention is suppressing that the cleaning performance which cleans a charging member falls.

  The charging device according to claim 1 is spirally wound around the outer peripheral surface of the charging member, the core member, and the outer periphery of the core member that are rotated by following the rotating image holder to charge the image holding member, and have a width. A cleaning material in which the height of the end portion in the direction is higher than the height of the central portion in the width direction, and the charging material contacts the charging member from above in the direction of gravity and rotates on the charging member A cleaning member that rotates following and rotates to clean the charging member, and supports the core material rotatably, and from a contact state in which the cleaning member is brought into contact with the charging member by its own weight from the upper side to above the core material. A supporting member that allows the movement of the core material and allows the upward movement of the core material to be equal to or less than the difference between the height of the end portion in the width direction of the cleaning material and the height of the central portion. It is characterized by that.

  A charging device according to a second aspect is the charging device according to the first aspect, wherein the support member allows the core material to move downward from the contact state and allows the core material to move downward. The allowable amount is the same as the allowable amount that allows the core material to move upward from the contact state.

  According to a third aspect of the present invention, there is provided an image forming apparatus according to the first or second aspect, an image holding member that is charged when a charging member provided in the charging device is driven and rotated, and the charged image. An exposure device that exposes a holding member to form an electrostatic latent image and a developing device that develops the electrostatic latent image are provided.

  According to the charging device of claim 1, compared with the case where the allowable amount allowing the upward movement of the core material is larger than the difference between the height of the end portion in the width direction of the cleaning material and the height of the central portion, It can suppress that the cleaning performance which cleans a charging member falls.

  According to the charging device of claim 2, the charging member is smaller than the case where the allowable amount allowing the downward movement of the core material is not the same as the allowable amount allowing the upward movement of the core material. It is possible to suppress the occurrence of uneven cleaning.

  According to the image forming apparatus of the third aspect, compared to the case where the charging device according to the first or second aspect is not provided, the image quality of the output image caused by poor cleaning of the charging member is suppressed. can do.

It is the expansion perspective view which showed the charging device which concerns on embodiment of this invention. It is sectional drawing which showed the cleaning member used for the charging device which concerns on embodiment of this invention. 1 is an enlarged front view illustrating a charging device according to an embodiment of the present invention. It is the front view which showed the charging device which concerns on embodiment of this invention. (A) (B) (C) It is process drawing which showed the cleaning process of the cleaning member used for the charging device which concerns on embodiment of this invention. 1 is a schematic configuration diagram illustrating an image forming unit of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

  An example of a charging device and an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. The arrow Y direction shown in the figure is the vertical direction, indicating the vertical direction of the apparatus, the arrow X direction is the horizontal direction, indicating the apparatus width direction, and the arrow Z direction is the horizontal direction, indicating the apparatus depth. Indicates.

(overall structure)
As shown in FIG. 7, the image forming apparatus 10 includes a first housing 12, a second housing 14, an image forming unit 16, a medium transport unit 50, a post-processing unit 60, and a control unit 68. , Including. The control unit 68 controls each part (such as each part constituting the image forming part 16) constituting the image forming apparatus 10.

  The first housing 12 and the second housing 14 are arranged side by side in the apparatus width direction and are connected by a connecting mechanism 44.

[Image forming unit 16]
The image forming unit 16 is disposed inside the first housing 12 and, as shown in FIG. 6, a toner image forming unit 20 that forms a toner image and an image formed by the toner image forming unit 20 as a recording medium And a fixing device 40 for fixing the toner image transferred to the sheet member P to the sheet member P. The image forming unit 16 forms an image on the sheet member P by an electrophotographic method.

[Toner image forming unit 20]
The toner image forming unit 20 includes a photosensitive drum 21 as an example of an image holding member, a charging device 22, an exposure device 23, and a developing device 24. A plurality of toner image forming units 20 are provided so as to form a toner image for each color. In the present embodiment, a toner image forming unit 20 of a total of four colors of yellow (Y), magenta (M), cyan (C), and black (K) is provided. The toner image forming units 20 of the respective colors have the same structure, and yellow (Y), magenta (M), and cyan (C) from the upstream side in the circumferential direction of the transfer belt 31 provided in the transfer device 30. The toner image forming unit 20 is arranged so that the photosensitive drum 21 of the toner image forming unit 20 of each color is in contact with the transfer belt 31 in the order of black (K). The toner image forming units 20 for each color are arranged side by side in the apparatus width direction. If there is no need to distinguish between Y, M, C, and K, Y, M, C, and K may be omitted.

  The photosensitive drum 21 is formed in a cylindrical shape, and is driven to rotate around its own axis by a driving unit (not shown). As an example, a photosensitive layer having a negative charging polarity is formed on the outer peripheral surface of the photosensitive drum 21. Note that an overcoat layer may be formed on the outer peripheral surface of the photosensitive drum 21.

  The charging device 22 is a charging member that contacts the outer peripheral surface (photosensitive layer) of the photosensitive drum 21 and rotates while being driven by the rotating photosensitive drum 21 to charge the outer peripheral surface of the photosensitive drum 21 to a negative polarity. As an example, a charging roll 70 is provided. Details of the charging device 22 will be described later.

  The exposure device 23 is configured to form an electrostatic latent image on the outer peripheral surface of the photosensitive drum 21. Specifically, in accordance with the image data received from the image signal processing unit constituting the control unit 68, the exposure light L modulated is irradiated onto the outer peripheral surface of the photosensitive drum 21 charged by the charging device 22. ing. An electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 21 by irradiation with the exposure light L.

  In the present embodiment, the exposure device 23 exposes the outer peripheral surface of the photosensitive drum 21 while scanning a light beam emitted from a light source (not shown) with an optical scanning unit (optical system) including a polygon mirror and an Fθ lens. It has a configuration.

  The developing device 24 develops the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 21 as a toner image with the developer G including the toner T (an example of powder) and the carrier CA, so that the photosensitive drum 21 is developed. A toner image is formed on the outer peripheral surface of the toner. A toner cartridge 39 for replenishing toner T to the developing device 24 is connected to the developing device 24 via a conveyance path (not shown). The toner cartridges 39 for the respective colors are arranged above the exposure device 23 in the apparatus width direction, and are individually detachable (replaceable) with respect to the first housing 12.

  The transfer device 30 includes an endless transfer belt 31 to which the toner images of the photosensitive drums 21 of the respective colors are transferred. The transfer belt 31 is wound around a plurality of rolls 32 to determine the posture. In the present embodiment, the transfer belt 31 has a reverse obtuse triangular posture that is long in the apparatus width direction when viewed from the front side.

  Among the plurality of rolls 32, the roll 32D functions as a drive roll that rotates the transfer belt 31 in the direction of arrow A by the power of a motor (not shown). Further, among the plurality of rolls 32, the roll 32 </ b> T functions as a tension applying roll that applies tension to the transfer belt 31. Among the plurality of rolls 32, the roll 32 </ b> B functions as a counter roll of a secondary transfer roll 34 described later.

  Further, primary transfer rolls 33 for transferring a toner image formed on the outer peripheral surface of the photoconductive drum 21 to the transfer belt 31 are arranged on the opposite sides of the photoconductive drums 21 of the respective colors across the transfer belt 31. .

  Further, a secondary transfer roll 34 for transferring the toner image transferred to the transfer belt 31 to the sheet member P is in contact with the top of the lower end side forming an obtuse angle of the transfer belt 31, and the transfer belt 31 and the secondary transfer roller 31 are in contact with each other. A transfer nip NT is formed with the roll 34.

  The fixing device 40 fixes the toner image onto the sheet member P to which the toner image has been transferred by the transfer device 30. In the present embodiment, the fixing device 40 fixes the toner image on the sheet member P by applying pressure while heating the toner image in the fixing nip NF.

[Medium transport unit 50]
As shown in FIG. 7, the medium conveyance unit 50 includes a medium supply unit 52 that supplies the sheet member P to the image forming unit 16, and a medium discharge unit 54 that discharges the sheet member P on which the image is formed. It consists of Further, the medium conveyance unit 50 includes a medium return unit 58 used when images are formed on both surfaces of the sheet member P, and an intermediate conveyance unit 59 that conveys the sheet member P from the transfer device 30 to the fixing device 40. It consists of

  The medium supply unit 52 supplies the sheet members P one by one to the transfer nip NT of the image forming unit 16 in accordance with the transfer timing. In contrast, the medium discharge unit 54 discharges the sheet member P on which the toner image is fixed by the fixing device 40 to the outside of the device. Further, when the medium returning unit 58 forms an image on the other side of the sheet member P on which the toner image is fixed on one side, the medium returning unit 58 inverts the front and back of the sheet member P to form the image forming unit 16 (medium supply unit). 52).

[Post-processing unit 60]
As shown in FIG. 7, the post-processing unit 60 is disposed inside the second housing 14 and corrects the curvature of the sheet cooling member 62 and the medium cooling unit 62 that cools the sheet member P on which the image is formed. The correction apparatus 64 includes an image inspection unit 66 that inspects an image.

  The components constituting the post-processing unit 60 are disposed in the medium discharge unit 54 of the medium transport unit 50, and the medium cooling unit 62, the correction device 64, and the image inspection unit 66 are upstream in the discharge direction of the sheet member P. Are arranged in this order.

(Image forming operation)
Next, an outline of an image forming process on the sheet member P and a post-processing process by the image forming apparatus 10 will be described.

  Upon receiving the image formation command, the control unit 68 operates the toner image forming unit 20, the transfer device 30, and the fixing device 40. As a result, the developing roll (not shown) provided in the photosensitive drum 21 and the developing device 24 is rotated, and the transfer belt 31 is rotated. Further, the pressure roll 42 provided in the fixing device 40 is rotated and the fixing belt (reference numeral omitted) is rotated. In synchronization with these operations, the control unit 68 operates the medium transport unit 50 and the like.

  As a result, the photosensitive drums 21 of the respective colors are charged by the charging device 22 while rotating. In addition, the control unit 68 sends the image data subjected to the image processing by the image signal processing unit to the exposure device 23 for each color. Each color exposure device 23 emits exposure light L of each color according to the image data and exposes the charged photosensitive drum 21 of each color. Then, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 21 of each color. The electrostatic latent image formed on the photosensitive drum 21 of each color is developed as a toner image by the developer G supplied from the developing device 24. As a result, toner images of corresponding colors among yellow (Y), magenta (M), cyan (C), and black (K) are formed on the photosensitive drums 21 of the respective colors.

  Further, the toner images of the respective colors formed on the photosensitive drums 21 of the respective colors are sequentially transferred to the transfer belt 31 that is circulated by the primary transfer rolls 33 of the respective colors. As a result, a toner image in which toner images for four colors are superimposed is formed on the transfer belt 31. This toner image is conveyed to the transfer nip NT by the rotation of the transfer belt 31. A sheet member P is supplied to the transfer nip NT by the medium supply unit 52 so as to synchronize with the conveyance of the toner image. A toner image is transferred from the transfer belt 31 to the sheet member P by applying a transfer bias voltage at the transfer nip NT.

  The sheet member P to which the toner image has been transferred is conveyed by the intermediate conveying unit 59 from the transfer nip NT of the transfer device 30 toward the fixing nip NF of the fixing device 40 while being sucked with negative pressure. The fixing device 40 applies heat and pressure (fixing energy) to the sheet member P that passes through the fixing nip NF. As a result, the toner image transferred to the sheet member P is fixed to the sheet member P.

  The sheet member P discharged from the fixing device 40 is processed by the post-processing unit 60 while being conveyed by the medium discharge unit 54 toward the discharge medium receiving unit outside the apparatus. The sheet member P heated by the fixing device 40 is first cooled in the medium cooling unit 62. Next, the curvature of the sheet member P is corrected by the correction device 64. Further, the toner image fixed on the sheet member P is detected by the image inspection unit 66 for the presence or absence of toner density defects, image defects, image position defects, and the like. Then, the sheet member P is discharged to the outside of the second housing 14 by the medium discharge unit 54.

  On the other hand, when an image is formed on the non-image surface (back surface) where the image of the sheet member P is not formed (in the case of double-sided printing), the control unit 68 transports the sheet member P that has passed the image inspection unit 66. The path is switched from the medium discharge unit 54 to the medium return unit 58. As a result, the sheet member P is turned upside down and sent to the medium supply unit 52. An image is formed (fixed) on the back surface of the sheet member P in the same process as described above, and is discharged to the outside of the second housing 14 by the medium discharge unit 54.

(Main part configuration)
Next, the charging device 22 will be described.

  As shown in FIG. 4, the charging device 22 is disposed above the photosensitive drum 21, and a charging roll 70 (an example of a charging member) that charges the outer peripheral surface of the photosensitive drum 21 to a negative polarity, and the charging roll 70. And a cleaning member 72 for cleaning the surface. Further, the charging device 22 includes a pair of support members 90 that rotatably support the charging roll 70 and the cleaning member 72.

[Charging roll 70]
The charging roll 70 includes a shaft member 70A having a columnar shape extending in the apparatus depth direction, and a cylindrical roll member 70B through which the shaft member 70A passes. As shown in FIG. 4, the charging roll 70 is disposed so as to contact the outer peripheral surface of the photosensitive drum 21 from the upper side of the photosensitive drum 21. Further, the shaft member 70 </ b> A of the charging roll 70 is rotatably supported by a pair of support members 90 disposed at both ends of the charging roll 70.

  In this configuration, the charging roll 70 is rotated by being driven by the rotating photosensitive drum 21. The charging roll 70 charges the surface of the photosensitive drum 21 by applying a voltage from a power source (not shown) to the charging roll 70 that rotates following the photosensitive drum 21.

[Cleaning member 72]
As shown in FIG. 4, the cleaning member 72 includes a core member 74 that is formed in a columnar shape extending in the apparatus depth direction, and a cleaning member 76 that is spirally wound around the outer peripheral surface of the core member 74. The cleaning material 76 of the cleaning member 72 is disposed so as to contact the outer peripheral surface of the charging roll 70 from the upper side of the charging roll 70. Further, the core member 74 of the cleaning member 72 is rotatably supported by a pair of support members 90 disposed at both ends of the cleaning member 72.

  As an example, the cleaning material 76 is formed of a urethane resin foam material, and has a rectangular cross section in a free state where the cleaning material 76 is not wound around the outer peripheral surface of the core material 74. Further, the cleaning material 76 is fixed to the outer peripheral surface of the core material 74 by using a double-sided tape (not shown).

  In the state where the cleaning material 76 is wound around the core material 74, as shown in FIG. 2, both end portions 76A in the width direction of the cleaning material 76 are more in the radial direction of the core material 74 than the central portion 76B. Protruding (warping). In other words, when the cleaning material 76 is wound around the core material 74, the height of the end 76A in the width direction of the cleaning material 76 is higher than the height of the central portion 76B in the width direction. In the present embodiment, the difference between the height of the end portion 76A of the cleaning material 76 and the height of the central portion 76B is a dimension H as shown in FIG. Specifically, when viewed from the depth direction of the apparatus, the height (T1) of the end portion 76A of the cleaning material 76 with respect to the line R extending in the horizontal direction through the center of the core material 74 and the height (T2) of the central portion 76B. Is the dimension H.

  Further, in the contact state where the cleaning material 76 of the cleaning member 72 is in contact with the charging roll 70 from above (hereinafter simply referred to as “contact state”), the end of the cleaning material 76 is compressed by the weight of the cleaning member 72, The central portion 76B of the cleaning material 76 and the charging roll 70 (see the two-dot chain line in FIG. 2) are in contact with each other. That is, the amount of compression of the cleaning material 76 in the contact state is set to the dimension H or more.

  In this configuration, the cleaning member 72 rotates following the rotating charging roll 70 to clean the surface of the charging roll 70.

[Support member 90]
As shown in FIG. 4, the charging roll 70 and the support member 90 that rotatably supports the cleaning member 72 are disposed at both ends of the cleaning member 72. As shown in FIGS. 1 and 3, the support member 90 is formed with a recess 92 into which both ends of the core member 74 are inserted.

  The concave portion 92 has a long hole shape (slot shape) extending in the vertical direction when viewed from the depth direction of the apparatus (the rotational axis direction of the core member 74) in order to allow variation between the axes of the cleaning member 72 and the charging roll 70. Yes. Thereby, the vertical movement of the core member 74 is allowed. The allowable amount (dimension J shown in FIG. 1) that allows the core member 74 to move upward from the contact state is equal to or less than the dimension H (see FIG. 2) described above. Further, an allowable amount (dimension K shown in FIG. 1) that allows the core material 74 to move downward from the contact state is an allowable amount (dimension shown in FIG. 1) that allows the core material 74 to move upward from the contact state. J).

(Function)
Next, the operation of the charging device 22 will be described with reference to an operation in which the cleaning member 72 removes extraneous matter such as a toner external additive attached to the surface of the charging roll 70 and cleans the surface of the charging roll 70.

  As shown in FIGS. 5A and 5B, the adhering matter adhering to the surface of the charging roll 70 rotating in the direction of the arrow is applied to one end 76A of the cleaning material 76 of the cleaning member 72 that rotates following the rotation. Pressed and aggregated. Specifically, the adhering matter is formed by the thickness direction of the cleaning member 72 (G direction shown in FIG. 5A) when the one end 76A of the cleaning material 76 is pushed by the surface of the charging roll 70, and the width direction. By being elastically deformed (elastically compressed) in the W direction shown in FIG. 5A, the cleaning material 76 is pressed and aggregated. Then, as shown in FIG. 5C, the aggregated deposits are loosened from a dense state by this restoring force when the end portion 76A of the cleaning material 76 of the cleaning member 72 that is driven to rotate is restored. It is repelled from the outer peripheral surface of the charging roll 70. As described above, the cleaning member 72 cleans the surface of the charging roll 70.

(Summary)
Here, the cleaning member 72 is configured by winding the cleaning material 76 around the core material 74 in a spiral shape. For this reason, compared with the cleaning member which coat | covers a cylindrical roll material on a core material, the outer diameter dimension of the cleaning member 72 may vary partially (it may change). As a result, the rotating charging roller 70 and the rotating cleaning member 72 driven and rotated may move (vibrate) in the vertical direction.

  However, the allowable amount (dimension J shown in FIG. 1) that allows the core material 74 to move upward from the contact state is the difference between the height of the end portion 76A of the cleaning material 76 and the height of the central portion 76B (FIG. 1). The dimension H) shown in FIG. Further, the amount of compression of the cleaning material 76 in the contact state is set to a dimension H or more. For this reason, even when the core member 74 moves upward from the contact state, the end portion 76A of the cleaning material 76 and the charging roll 70 are in contact with each other. Thereby, it is suppressed that the cleaning performance which cleans the charging roll 70 falls.

  The cleaning member 72 is configured by winding the cleaning material 76 around the core material 74 in a spiral shape. For this reason, since the cutting process which cuts the outer surface of a roll material becomes unnecessary compared with the cleaning member which coat | covers a cylindrical roll material on a core material, the cost of the cleaning member 72 is reduced. In other words, it is possible to suppress a reduction in cleaning performance for cleaning the charging roll 70 while reducing the cost.

  Further, the allowable amount (dimension K shown in FIG. 1) that allows the core material 74 to move downward from the contact state is the allowable amount that allows the core material 74 to move upward from the contact state (dimension shown in FIG. 1). J). For this reason, even when the cleaning member 72 that rotates following the charging roll 70 moves (vibrates) in the vertical direction, the amplitude is regulated by the recess 92, and the amount of movement from the contact state to the upper side and the contact state to the lower side. Therefore, the cleaning member 72 is prevented from being biased and vibrated. For this reason, the occurrence of uneven cleaning on the charging roll 70 is suppressed.

  Further, in the image forming apparatus 10, the deterioration of the quality of the output image is suppressed by suppressing the deterioration of the cleaning performance for cleaning the charging roll 70.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. This will be apparent to those skilled in the art. For example, in the above-described embodiment, the cleaning material 76 is formed of an elastically deformable urethane resin foam material. However, the cleaning material 76 is not limited to this material, and in the state where the cleaning material 76 is wound around the core material 74, the cleaning material 76 is used. Any elastic material may be used as long as both ends 76A in the width direction 76 are higher than the height of the central portion 76B.

10 Image forming apparatus 21 Photosensitive drum (an example of an image carrier)
22 charging device 23 exposure device 24 developing device 70 charging roll (an example of a charging member)
72 Cleaning member 74 Core material 76 Cleaning material 90 Support member

Claims (3)

A charging member that rotates following the rotating image carrier and charges the image carrier;
A core material, and a cleaning material that is spirally wound around the outer peripheral surface of the core material and has a height at the end in the width direction higher than the height at the center in the width direction. A cleaning member that comes into contact with the cleaning material from above in the direction of gravity and that rotates following the rotating charging member to clean the charging member;
The core material is rotatably supported, and the core member is allowed to move upward from a contact state in which the cleaning member is brought into contact with the charging member by its own weight from above, and the core material is allowed to move upward. A support member that allows an allowable amount to be equal to or less than a difference between the height of the end portion in the width direction of the cleaning material and the height of the central portion;
A charging device comprising:   The support member allows the core material to move downward from the contact state and allows the core material to move downward from the contact state to allow the core material to move upward. The charging device according to claim 1, wherein the charging device is the same as an allowable amount. The charging device according to claim 1 or 2,
An image holding member that is charged by being driven and rotated by a charging member provided in the charging device;
An exposure device that exposes the charged image carrier to form an electrostatic latent image;
A developing device for developing the electrostatic latent image;
An image forming apparatus comprising:

Images