JP2004163708A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To separate an electrifying member by which an electrifying action is imparted to a photoreceptor drum when the photoreceptor drum is stopped by holding the electrifying member at a position where it comes into contact with the photoreceptor drum only when the photoreceptor drum is rotated. <P>SOLUTION: A brush gear 42 is combined with the photoreceptor drum 31 arranged at the recording part of an image forming apparatus through an idler gear 50 so as to transmit driving to the electrifying brush 40, and a slider 43 is provided to a guide groove 42 where a frame 34 is provided with a brush shaft 41, and the slider 43 is provided with a resistance imparting means. Then, when the photoreceptor drum 31 is rotated, the slider 43 is moved along a guide groove 44 by the rotation of the brush shaft 41, and the electrifying brush 40 comes into contact with the photoreceptor drum 31 and is rotated, so that the electrifying action is imparted. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus in which a charging unit is provided so as to be able to be separated from and contacted with a photosensitive drum, and the charging unit is brought into contact only when the photosensitive drum is driven to rotate.
[0002]
[Prior art]
In a facsimile machine or an image forming apparatus having both a facsimile function and a copying function, a toner image is formed on a photosensitive drum by using an electrophotographic method, and a sheet on which the toner image is transferred is thermally transferred through a fixing device. And a mechanism for applying pressure and fixing the image and then discharging the image. In the image forming apparatus using the electrophotographic method, a unit of a photosensitive drum and a developing device for supplying toner to the photosensitive drum are arranged in combination. Further, with respect to the photosensitive drum provided in the photosensitive unit, a charging member and an image writing member, a transfer member and a memory removing member are arranged around the photosensitive drum, and the charging member uniformly charges the surface of the photosensitive drum. Is performed, a writing member irradiates light of the image to form an electrostatic latent image, and the toner with the electrostatic latent image is adhered to make the toner image a visible image, and the toner image is transferred to paper. Like that.
[0003]
When the image forming apparatus is small, a contact charging member such as a roller or a brush roller made of an elastic body is often used. Then, by applying a predetermined voltage to the contact charging member and sliding the surface of the photoconductor drum to a predetermined value, the surface of the photoconductor drum is charged to a predetermined value. However, when the charging member is configured to be constantly in contact with the photosensitive drum, the bristle of the charging brush as the charging member is constantly pressed against the photosensitive drum at the stop position. This causes a problem that the subsequent charging operation cannot be performed satisfactorily. Therefore, in order to solve the above-described problem, a driving means such as providing a charging member detachably using a driving source such as a solenoid with respect to the photosensitive drum is used (for example, And Patent Document 1).
[0004]
[Patent Document 1]
JP 2000-66481 A [0005]
[Problems to be solved by the invention]
However, as in the above-described conventional example, it is necessary to separately provide the driving source when the charging member disposed on the photosensitive drum is configured to be separated from and connected to the photosensitive drum using driving means such as an actuator. It is. Since the power supply means for the drive source, the control mechanism, and the like are incorporated in the apparatus, there is a problem in that the structure of the apparatus is restricted and the manufacturing cost is greatly affected.
[0006]
According to the present invention, the charging brush as the charging unit is provided by using an interlocking unit that contacts only when the photosensitive drum is rotated, and when the apparatus is not used, the charging brush is separated from the photosensitive drum. It is intended to provide a device that can be supported.
[0007]
[Means for Solving the Problems]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a photosensitive drum which is driven to rotate, and is provided so as to be detachable from the surface of the photosensitive drum, and charges the surface of the photosensitive drum in a contact state. A charging unit for causing the charging unit to constantly apply a biasing force to the charging unit in a direction away from the photosensitive drum; and a biasing force of the biasing unit in conjunction with the rotation of the photosensitive drum. And a planetary gear means for revolving the charging means with respect to the photosensitive drum and bringing the charging means into contact with the surface of the photosensitive drum.
[0008]
The invention according to claim 2 is characterized in that the urging means and the planetary gear means are provided at both ends in the longitudinal direction of the photosensitive drum.
[0009]
The invention according to claim 3 is characterized in that only one of the planetary gear means rotates the charging means when the charging means comes into contact with the photosensitive drum in conjunction with the rotation of the photosensitive drum.
[0010]
With the above-described configuration, the operation of bringing the charging unit into contact with the photoconductor drum can be performed using only the rotation of the photoconductor drum. Therefore, it is necessary to separately provide a drive source such as an actuator. In addition, the configuration of the device and the operation of control can be simplified. Further, the urging means provided for the charging means urges the charging means in a direction away from the photosensitive drum, so that when the rotation of the photosensitive drum is stopped, the charging means can be immediately separated. When the charging means is in contact with the photosensitive drum, the charging means can be rotated by the planetary gear of the charging means provided on the gear of the photosensitive drum to perform a charging operation on the surface of the photosensitive drum.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The configuration of the device of the present invention will be described with reference to the illustrated example. The example shown in FIG. 1 shows a relationship between a photoconductor unit 30 arranged in a recording unit of an image forming apparatus and a developing unit 21 for supplying toner. In the recording unit 20 of the image forming apparatus, a developing unit 21 and a photoreceptor unit 30 are arranged in combination, and the developing unit 21 is provided with a paddle 23 on a toner hopper 22 containing toner. . Then, while stirring the toner with the paddle 23, the toner is attached to the developing roller 25 via the supply roller 24, and a thin layer of the toner is formed by the blade 26, and is supplied to the photosensitive drum 31. The toner carried as a thin layer on the developing roller 25 is frictionally charged between the supply roller 24 and the developing roller 25 by rotating the developing roller 25 in the same direction, and the charged toner is transferred to the photosensitive drum. The image is transferred toward the electrostatic latent image formed on the image 31.
[0012]
In the photoconductor unit 30 arranged in combination with the developing unit 21, the surface of the photoconductor drum 31 is charged to a uniform potential with respect to the rotation direction of the photoconductor drum 31 (clockwise direction in the figure). A writing device 37 including a charging brush 40 and a light emitting member such as an LED is provided. A transfer roller 39 for transferring a toner image to a sheet is disposed downstream of the developing unit corresponding to the developing roller 25. An upstream portion of the charging brush 40 is provided after transferring the toner image to the sheet. There is provided a memory removing brush 38 for disturbing the remaining toner, paper dust separated from the paper, and other dust-like foreign matters to weaken the adhesive force and remove a part thereof.
[0013]
As described above, in the photoconductor drum 31 provided in the photoconductor unit 30, the surface of the photoconductor is uniformly charged by the charging brush 40 to which a predetermined potential is applied. The electrostatic latent image is formed by irradiating light, toner is supplied from the developing roller 25 to the electrostatic latent image, and the electrostatic latent image is visualized as a toner image. A predetermined potential is applied to the toner image carried on the photosensitive drum from the back side of the sheet passing between the transfer roller 39 and the photosensitive drum by the transfer roller 39, and the potential difference is applied to the sheet by the potential difference. Transcribed. Then, the sheet carrying the toner image is conveyed toward the fixing device 27 and fixed, and the sheet on which the image is formed is discharged to a discharge tray 29 by a discharge roller device 28.
[0014]
The example shown in FIGS. 2 to 4 describes a mechanism for moving a photosensitive drum 31 and a charging brush 40 as a contact charging member to and away from the photosensitive drum 31 in the photosensitive unit 30 as the process unit. Is what it is. In the example shown in FIG. 2, the relationship between the photosensitive drum 31 and the charging brush 40 and the rotation of the photosensitive drum are transmitted to the charging brush 40, and the charging brush 40 is rotated by rotating the photosensitive drum. It is configured to contact and rotate. The photosensitive drum 31 has a shaft 32 rotatably held by a bearing 33 provided on the frame side plates 34 and 34a. When a signal for image formation is input, a drive gear ( (Not shown) to rotate at a predetermined peripheral speed. When the photosensitive drum 31 is rotated, the charging brush 40 is driven via idler gears 50 and 50a that mesh with output gears 36 and 36a provided on the photosensitive drum 31. The shafts 51, 51a of the idler gears 50, 50a are supported by the frames 34, 34a, respectively, and are always meshed with the photosensitive drum output gears 36, 36a.
[0015]
The charging brush 40, which is detachably attached to the photosensitive drum 31, has brush gears 42, 42a meshing with the idler gear 50 provided on the brush shaft 41, and supports both ends of the brush shaft 41. Sliders 43 and 43a are provided so as to be slidable with respect to guide grooves 44 (shown in FIGS. 3 and 4) formed in the frame 34. The sliders 43 and 43a supporting both ends of the brush shaft 41 are provided with resistance applying members 45 and 45a, each of which is a combination of a fixing ring 46 and a resistor 47. Further, an urging member 48 such as a spring is connected to a predetermined position of the brush shaft 41, and when the rotation of the photosensitive drum 31 is stopped, the urging member 48 moves the charging brush 40 to the photosensitive member. Be able to hold it in a position that does not touch the drum.
[0016]
In the drive transmission unit for the charging brush 40 configured as described above, the drive transmission to the charging brush 40 is not performed when the photosensitive drum 31 is not rotating, and therefore, FIG. As described above, the brush shaft 41 is positioned at the end of the guide groove 44 by the urging means 48. Since the charging brush 40 is stopped and held at a position where the charging brush 40 does not contact the photoconductor drum 31, it is assumed that the end of the brush bristles does not contact the photoconductor drum. The brush hairs do not fall over. The brush member of the charging brush 40 is made of a conductive fiber, and a predetermined voltage is applied to the shaft 41 via a power supply unit (not shown), and the photosensitive member on which the brush slides. The surface of the drum is charged to a predetermined potential.
[0017]
When the rotation of the photosensitive drum 31 is started, the rotation is transmitted from the output gear 36 to the brush gear 42 of the charging brush 40 via the idler gear 50. At the first stage of the rotation of the brush gear 42, the resistor 47 disposed between the fixing ring 46 of the resistance applying means 45 and the slider 43 acts as a resistance to the rotation of the charging brush 40. 43a revolves around the shafts 51, 51a and is moved along guide grooves 44 provided in the frame 34. Then, the slider 43 is moved to the end 44a of the guide groove 44 shown in FIG. 4, and the charging brush 40 is rotated around the shaft 41 in a state of being rubbed against the photoconductor drum, thereby charging the photoconductor drum. Perform the action. While the photosensitive drum is being rotated, the drive transmission mechanism is operating, so that the charging brush 40 is rubbed against the photosensitive drum 31 to continue the charging operation. When the rotation of the body drum is stopped, the resistance by the resistance applying means 45 disappears, and the action of returning the brush shaft by the urging means 48 is exerted, so that the charging brush 40 is separated from the photosensitive drum.
[0018]
As described above, only while the photosensitive drum is being driven, the charging brush 40 is rubbed against the photosensitive drum 31 to perform a charging action on the photosensitive drum, and the photosensitive drum is stopped. In this case, the charging brush 40 is forcibly separated from the photosensitive drum 31 and can be held. Therefore, by providing the resistance applying means 45 to the shaft 41 of the charging brush 40, the operation of automatically moving the charging brush 40 into and out of contact with the rotation of the photosensitive drum 31 can be performed. Becomes possible. The arrangement relationship of the gear of the drive transmission mechanism with respect to the shaft of the charging brush 40 and the configuration of the resistance applying means 45 provided on the shaft 41 are not limited to the configuration of the above-described embodiment. It is also possible to combine the drive transmission means and the resistance member. Further, as the resistor 47 provided in the resistance applying unit 45, a friction unit having an arbitrary configuration can be used. For example, a spring washer or the like may be used. After the movement, the shaft 41 may be allowed to rotate with respect to the slider 43 and the charging brush 40 may be rubbed against the photosensitive drum.
[0019]
The image forming apparatus using the photoreceptor unit 30 can be applied to a small image forming apparatus configured as shown in FIG. The image forming apparatus 1 can be configured as a multifunction machine combining a copying machine and a facsimile function, or an apparatus further combining an image input mechanism of a personal computer and a printer function. The image reading apparatus 2 using the ADF 3 is arranged at the upper part of the image forming apparatus 1, and the sheet feeding unit 15 equipped with an arbitrary number of sheet feeding trays 16 is arranged at the lower part. A recording unit 20 is provided between the apparatus 2 and the paper supply unit 15. In the image forming apparatus 1, as the paper feed tray 16 disposed in the paper feed unit 15, a conventionally known arbitrary paper feed tray or a paper storage device called a paper feed cassette can be used. The paper accommodated in the paper supply tray 16 is taken out by a paper supply roller 17, sent to a recording section 20 by conveyance roller devices 18 and 18 a through a paper conveyance path 19, and toner is applied to the paper by the recording section. The image is transferred, fixed through a fixing device 27, and the recording paper is discharged to a discharge tray 29.
[0020]
An image reading device having an arbitrary configuration is disposed above the recording unit 20, and means for transmitting image information obtained by scanning a document to the image information processing unit of the image forming apparatus and transmitting the image information to the writing device 37 is provided. Provided. As the image reading device, an FBS (flatbed scanner) or an ADF (automatic document feeder) used in combination with a general image forming device can be used. Also, as the reading device, a mechanism that reciprocates in the length direction of a platen that holds a document by combining a full-rate carriage that carries a lamp and a mirror and a half-rate carriage that carries two mirrors may be used. It is possible.
[0021]
The image reading apparatus 2 provided in the image forming apparatus 1 is a combination of the ADF 3 and the reading apparatus 12 arranged at a fixed position. The reading apparatus 12 corresponds to the reading section 6 provided in the document conveying path 5 of the ADF 3. Then, the lamp 13 is arranged to irradiate the image surface of the document conveyed at a predetermined speed in the document conveyance path 5. The light reflected from the original is combined with a plurality of mirrors to form an optical path, formed into an image on a CCD 14 via a lens (not shown) 1, and the CCD 14 converts an optical signal into a digital signal. The information is transmitted to the image information processing unit of the image forming apparatus.
[0022]
The ADF 3 is provided with a document transport path 5 configured in a substantially U-shape in the horizontal direction, similarly to the ADF generally used conventionally. An original is taken out from an original tray 4 arranged on the upstream side of the original conveying path 5 by a pickup roller 7, and is separated between a separate roller 8 a and a retard roller 8 b of a separation unit 8 to convey the separated original one by one. The sheet is conveyed at a constant speed by the conveying roller devices 9 and 9a arranged on the path 5. Then, the document is read by the scanning device 12 on a platen portion of the reading unit 6 provided below the document conveying path 5, and when the reading operation is completed, the document is discharged to the document discharge tray 11 by the discharge roller device 10. It is configured.
[0023]
The charging member provided in the photoreceptor unit disposed in the recording section of the image forming apparatus can be configured by using any conventionally known conductive fiber material as the brush member. Further, the conditions such as the electrical conductivity of the conductive fibers constituting the brush may be made of any material corresponding to the photosensitive drum provided in the unit. Further, the image forming apparatus using the photoreceptor unit is not limited to the mechanism disclosed in the embodiment, and may be configured as an apparatus for mounting any conventionally known arbitrary unit to a recording unit. You can also.
[0024]
【The invention's effect】
With the above-described configuration, the operation of bringing the charging unit into contact with the photoconductor drum can be performed using only the rotation of the photoconductor drum. Therefore, it is necessary to separately provide a drive source such as an actuator. In addition, the configuration of the device and the operation of control can be simplified. Further, the urging means provided for the charging means urges the charging means in a direction away from the photosensitive drum, so that when the rotation of the photosensitive drum is stopped, the charging means can be immediately separated. When the charging means is in contact with the photosensitive drum, the charging means can be rotated by the planetary gear of the charging means provided on the gear of the photosensitive drum to perform a charging operation on the surface of the photosensitive drum.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a configuration of a recording unit of an image forming apparatus.
FIG. 2 is a front view of a photoconductor unit.
FIG. 3 is a side view of the apparatus of FIG. 2, illustrating a state in which a charging brush is held at a stop position.
FIG. 4 is a diagram illustrating a state in which a charging brush is in contact with a photosensitive drum.
FIG. 5 is an explanatory diagram illustrating an overall configuration of the image forming apparatus.
[Explanation of symbols]
1 image forming device, 2 image reading device, 3 ADF,
4 document tray, 5 document feed path, 6 reading section,
7 pickup roller, 8 separation unit, 9 transport roller device,
10 discharge roller, 11 document discharge tray, 12 reading device,
13 lamps, 14 CCD, 15 paper feeder,
16 paper feed tray, 17 paper feed roller, 18 transport roller device,
19 paper transport path, 20 recording unit, 21 developing unit,
22 toner hopper, 23 paddle, 24 supply roller,
25 developing roller, 26 blade, 27 fixing device,
28 discharge roller device, 29 discharge tray,
30 photoconductor unit, 31 photoconductor drum, 32 axes,
33 bearings, 34 frames, 35 input gears,
36 output gear, 37 writing device, 38 memory removing member,
39 transfer roller, 40 charging brush, 41 brush shaft,
42 brush gear, 43 slider, 44 guide groove,
45 resistance applying means, 46 fixing ring, 47 resistor,
48 springs, 50 idler gears, 51 shafts.

Claims (3)

A photosensitive drum that is driven to rotate,
A charging unit that is provided detachably on the surface of the photoconductor drum and charges the surface of the photoconductor drum in a contact state;
An urging unit that constantly applies an urging force to the charging unit in a direction away from the photosensitive drum;
In conjunction with the rotation of the photosensitive drum, the charging means is brought into contact with the photosensitive drum against the urging force of the urging means, and the charging means is rotated while sliding on the surface of the photosensitive drum. An image forming apparatus comprising: a planetary gear unit. The image forming apparatus according to claim 1, wherein the urging unit and the planetary gear unit are provided at both ends in a longitudinal direction of the photosensitive drum. The image forming apparatus according to claim 2, wherein only one of the planetary gear units rotates the charging unit when the charging unit comes into contact with the photosensitive drum in conjunction with the rotation of the photosensitive drum. apparatus.

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