JP2007065687A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can normalize an engaged state of gears, even in case a tooth contact is generated, when a photosensitive drum is inserted into a device frame. <P>SOLUTION: An image forming apparatus includes a device frame and a photosensitive drum that is inserted into the device frame. The device frame includes a driving device, a driving gear that transmits a driving force from the driving device and an urging member that supports the driving gear in a manner capable of moving along a moving direction of a photosensitive drum and urges the driving gear in an opposite direction from a direction in which the photosensitive drum is inserted. The photosensitive drum includes a driven gear to be engaged with the driving gear. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus. In particular, the present invention relates to an image forming apparatus in which a driving force can be transmitted by engaging a driving gear on the apparatus main body side and a driven gear of the photosensitive drum after the photosensitive drum is mounted on the apparatus main body.

In an image forming apparatus that forms an image by transferring a toner image onto a sheet, when the photosensitive drum is mounted on the apparatus main body, the photosensitive drum is connected to a driving gear to which a driving force is transmitted from a driving source of the apparatus main body. There is a conventional invention in which a driven gear is engaged. In such a conventional image forming apparatus, when the photosensitive drum is used as a unit and the photosensitive drum unit is mounted on the apparatus main body, or when the photosensitive drum is mounted alone on the apparatus main body, the drive source of the apparatus main body Drive transmission to the photosensitive drum is performed (see, for example, Patent Document 1).
JP-A-8-115009

  However, there are cases where the drive gear and the driven gear do not mesh in a good state simply by mounting the photosensitive drum unit or the photosensitive drum to the apparatus main body. That is, there is a problem that the teeth of the driving gear of the apparatus main body and the teeth of the driven gear of the photosensitive drum are brought into contact with each other (i.e., are brought into contact with each other), and a normal meshing state is not achieved.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of easily normalizing the meshing state of gears even if tooth contact occurs when the photosensitive drum is mounted on the apparatus main body. The purpose is that.

  The present invention relates to a photosensitive drum including a driving device, a device main body including a driving gear for transmitting a driving force from the driving device, and a driven gear which is mounted on the device main body and meshed with the driving gear. And after the photosensitive drum is mounted on the apparatus main body, the drive gear and the driven gear are engaged with each other by driving the drive device and slightly rotating the drive gear. Features. Further, the drive gear is movable along the moving direction of the photosensitive drum, and the apparatus main body includes a biasing member that biases the driving gear in a direction opposite to the mounting direction of the photosensitive drum. It is characterized by including. Further, when the driving gear and the driven gear are in contact with each other when the photosensitive drum is mounted on the apparatus main body, the driving is performed by further mounting the photosensitive drum on the apparatus main body. The gear is pushed against the urging force of the urging member. Further, the drive device is a motor fixed to the frame of the device body, and the drive gear is attached to an output shaft of the motor so as to be slidable in the axial direction. Furthermore, a key extending substantially over the entire length of the output shaft is fixed to the output shaft, and the drive gear can be rotated together with the output shaft at any position of the output shaft. Further, the biasing member is a coil spring and is wound around the output shaft between the drive gear and the frame. Further, a shaft hole is formed in the frame, and the shaft of the photosensitive drum is inserted into the shaft hole in a state where the photosensitive drum is mounted on the apparatus main body. Further, the slight rotation of the drive gear is performed in an initialization step of the image forming apparatus.

  According to the present invention, when the photosensitive drum is mounted and the driven gear and the driving gear of the photosensitive drum do not mesh with each other, the tooth contact state is eliminated by merely rotating the driving gear slightly, and both gears are moved. Since the engagement is normal, the drive to the photosensitive drum can be transmitted satisfactorily. Since the drive gear is provided so as to be movable in the axial direction via the biasing means, even when the driven gear and the drive gear are in contact with each other, the operation for mounting the photosensitive drum is not performed. It does not become an obstacle.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  An image forming apparatus 1 according to an embodiment of the present invention will be described below. The image forming apparatus 1 is an electrophotographic image forming apparatus that transfers and fixes a toner image onto a sheet, and can be applied to a facsimile apparatus, a printer apparatus, a copying apparatus, or an apparatus having a composite function thereof. . The image forming apparatus 1 has a recording unit 10 for recording an image on a sheet using an electrophotographic method in the apparatus main body, and an image reading device 30 and an automatic document feeder (ADF) are provided above the apparatus main body 2. ) 40 will be described below. However, in the following embodiment, the configuration and the like of the image reading device 20 are not the gist of the invention. Therefore, the description thereof is simplified, and the drive transmission mechanism to the photosensitive drum 11 mounted on the apparatus main body 2 is mainly used. explain.

  In the image forming apparatus 1 shown in FIG. 1, one or more paper feed cassettes 4 are installed in a paper feed unit 3 provided at a lower portion of the apparatus main body 2. The paper is fed from the paper feed cassette 4 by the paper feed roller 5, and the fed paper is sent to the paper transport path 6 and transported toward the recording unit 10. Note that a plurality of paper feed cassettes 4 can be mounted in the paper feed unit 3, and a paper feed cassette 4 containing a sheet of a required size is selected from any paper feed cassette 4, and the selected paper feed cassette 4 is selected. Paper can be fed from the paper feed cassette 4. A plurality of transport roller devices 7 and 7a are arranged in the paper transport path 6 at a predetermined interval.

  In the paper transport path 6, the leading edge of the paper fed from the paper feed cassette 4 is abutted against the transport roller device 7 upstream of the recording unit 10, and in this state, the transport roller device 7a further upstream. An additional feeding action is applied to form a loop on the paper. Then, the leading edge of the sheet enters the nip of the transport roller device 7 to align the leading edge of the sheet, and stops in that state. Then, the conveyance roller device 7 is driven so that the toner image is formed on the photosensitive drum 11, and the sheet is conveyed toward the nip portion between the photosensitive drum 11 and the transfer roller 16. When a transfer voltage is applied to the transfer roller 16 while the sheet is nipped between the photosensitive drum 11 and the transfer roller 16, a toner image is transferred to the sheet.

  The recording unit 10 includes a photosensitive drum 11 as in a general electrophotographic apparatus. Around the photosensitive drum 11, a charging member 14, a writing member 15, a developing device 12, a transfer roller 16, and a cleaning device 18 are arranged along the rotation direction. The developing device 12 is provided on the downstream side of the writing member 14, and the developing roller 13 exposed to the outside is in contact with the photosensitive drum 11. In the recording unit 10, the surface of the photosensitive drum 11 is uniformly charged by the charging member 14, and the writing member 15 irradiates the image light with the electrostatic latent image on the surface of the photosensitive drum 11. An image is formed, and a toner image as a visible image is formed by supplying toner from the developing roller 13 to adhere to the electrostatic latent image.

  As described above, the toner image is transferred to the sheet by the transfer roller 16 to which a voltage of a predetermined value is applied when the sheet is conveyed while being nipped between the photosensitive drum 11 and the transfer roller 16. . When the paper passes through the fixing device 8, heat and pressure are applied to the toner image carried on the paper, and the toner image is fixed on the paper. Then, the paper is discharged by a discharge roller device 9 to a discharge tray (not shown). In addition, after the toner image formed on the photosensitive drum 11 is transferred to a sheet, the toner remaining on the photosensitive drum 11 without being transferred is scraped by the blade 18 constituting the cleaning device 17 and scraped off. The toner is conveyed toward a waste toner box (not shown).

  When the image forming apparatus 1 configured as described above is a small printer or the like, the photosensitive drum 11 arranged in the recording unit 10 is configured to be capable of forming about several thousand images. For this reason, when the number of formed images exceeds that, a command to replace the photosensitive drum 11 is displayed on a display device (not shown). The photoconductor drum 11 can be exchanged alone or as a photoconductor unit incorporating a peripheral member. In the present invention, either case may be used. By the way, in the image forming apparatus 1 of this embodiment, when the photosensitive drum 11 is mounted on the apparatus main body 2, the driving gear 24 of the driving mechanism of the apparatus main body 2 is a driven gear provided on the photosensitive drum 11. Is configured to mesh with the drum gear 25.

  As shown in FIG. 2, a driving device 21 is provided in the apparatus main body 2, and a drum gear 25 of the photosensitive drum 11 mounted on the apparatus main body 2 meshes with a main body gear 24 provided in the driving device 21. Yes. More specifically, the drive device 21 shown in FIG. 2 is fixed to the frame 20 of the apparatus body 2 and is constituted by a motor provided with a speed reduction mechanism. And the front-end | tip part of the output shaft 22 of this motor protrudes inside the recording part 2, and the drive gear 24 is attached to this front-end | tip part. The drive gear 24 is slidable along the output shaft 22 and is always directed toward the tip of the shaft by a spring 23 as a biasing member wound around the output shaft 22 between the drive gear 24 and the frame 20. It is energized. Since the output shaft 22 is fixed with a key extending in the entire axial direction, the drive gear 24 is rotated by the output shaft 22 regardless of the position of the output shaft 22 in the axial direction. It is possible. Further, on the photosensitive drum 11, a drum gear 25 is fixed at a position outside the image forming area. In the illustrated example, when the photosensitive drum 11 is mounted on the apparatus main body 2, the tip of the drum shaft 26 of the photosensitive drum 11 is inserted into the shaft hole of the frame 20, and the photosensitive drum 11 is attached to the apparatus main body. 2 is positioned.

  When the photosensitive drum 11 is mounted on the apparatus main body 2 for replacement or remounting of the photosensitive drum 11, if the photosensitive drum 11 is simply pushed along the shaft 26, in some cases, the drive gear 24 may be connected. The drum gear 25 may come into contact with the teeth and may not be in a good meshing state. That is, as will be described with reference to FIG. 3, a problem that the gear teeth come into contact (collision) at the tooth contact portion Z is likely to occur. When the drive gear 24 is fixedly attached to the output shaft 22, the drum gear 25 forcibly pushes the drive gear 24. In this case, when the photosensitive drum 11 is mounted, it is impossible to mount the photosensitive drum 11 satisfactorily unless an operation for rotating the photosensitive drum 11 at the same time as the pushing operation is added. A problem occurs.

  In order to eliminate the problem of gear tooth contact as described above, in the image forming apparatus 1 of this embodiment, the drive gear 24 on the apparatus body 2 side is connected to the shaft of the output shaft 22 as shown in FIG. The drive gear 24 is urged by a spring 23 from behind. Therefore, when the photosensitive drum 11 is mounted on the recording unit 10, as shown in FIG. 4, the drive gear 24 and the drum gear 25 collide with each other at the tooth contact portion Z, but the photosensitive member 11 resists the biasing force of the spring 23. When the body drum 11 is further pushed in, as shown in FIG. 5, the drive gear 24 is pushed back to the solid line position in the figure. Then, the photosensitive drum 11 is held at a predetermined operating position while keeping the contacted state. In this state, the drum gear 25 is not normally meshed with the drive gear 24, so that the photosensitive drum 11 cannot rotate normally.

  However, in the image forming apparatus 1 of this embodiment, the driving device 21 is driven in the state shown by the solid line in FIG. 5 and the output shaft 22 is slightly rotated, so that the gear teeth are pressed against each other. Is resolved. That is, when the output shaft 22 is slightly rotated and positioned at a position where the drive gear 24 and the drum gear 25 are engaged with each other, the drive gear 24 is moved to the drum gear 25 side by the urging force of the spring 23. Then, the drive gear 24 moves from the solid line position in FIG. 5 to the phantom line position, so that the drive gear 24 and the drum gear 25 are completely engaged, and the photosensitive drum 11 can be driven by the drive device 21. It becomes.

  As described above, it is preferable that the initialization step of the image forming apparatus 1 has a process of driving the driving device 21 for a short time after the photosensitive drum 11 is mounted on the recording unit 10. This initialization step is a step for confirming whether or not each member arranged in the recording unit 10 operates normally. That is, in a general image forming apparatus, after the photosensitive drum 11 is replaced or each member of the recording unit 10 is remounted, according to a control program set in the control device of the image forming apparatus 1. In the initialization operation, the photosensitive drum 11 is idled for a short time and the operation of each member is normally performed. Therefore, it is only necessary to normalize the meshing of the gear teeth using the operation as described above. Therefore, the mounting operation of the photosensitive drum 11 can be easily performed as compared with the conventional art.

  The image reading device 30 disposed on the upper portion of the apparatus main body 2 configured as described above is not particularly the gist of the present invention, but will be briefly described below. As shown in FIG. 1, a scanning device 35 that reads a document image in cooperation with the ADF 40 is provided at a fixed position of the upper frame 31. As shown in the figure, the scanning device 35 includes a plurality of mirrors 37, a lens 38, and a CCD 39 as one unit. The scanning device 35 is fixedly provided at a position corresponding to the platen 32 near the end of the upper frame 31. In the scanning device 35, the original moving while sliding the image surface on the platen 32 is irradiated with light from the lamp 36, and the reflected light is reflected by a plurality of mirrors 37. Is imaged on the CCD 39 by the lens 38, and optical information corresponding to the original is obtained as digital information.

  The ADF 40 includes a document tray 43 and a discharge tray 44 that are arranged so as to overlap each other at a predetermined interval, and these trays 43 and 44 are fixed on the upper frame 31. The ADF 40 includes a document conveyance path 41 that connects the two trays 43 and 44. The document conveyance path 41 is configured in a substantially U-shape in the horizontal direction, as in the conventional automatic document conveyance device. Has been. A platen 32 is provided below the curved portion of the document conveyance path 41, and the documents taken out one by one by the paper feeding device 42 are being conveyed in the document conveyance path 41 at a constant speed. Reading is done.

  Note that the apparatus main body 2 provided with the recording unit 10 as described above and the image reading apparatus 30 arranged on the upper part of the apparatus main body 2 can be combined to form a multifunction machine having the functions of a copying machine and a facsimile machine. it can. Further, it is possible to use only the apparatus main body 2 as a printer without providing an image reading device on the upper part of the apparatus main body 2. In addition, the image reading apparatus disposed on the upper part of the apparatus main body 2 may be a mechanism that can support both the FBS (flatbed scanner) function and the ADF function.

1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a state where the drum gear of the photosensitive drum and the drive gear on the apparatus main body side are normally meshed with each other. FIG. 5 is a perspective view showing a state where the drum gear of the photosensitive drum and the drive gear on the apparatus main body side are in contact with each other. FIG. 4 is a cross-sectional view of FIG. 3. FIG. 6 is a diagram illustrating an operation in the middle of mounting the photosensitive drum to the apparatus main body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 10 Recording part 11 Photosensitive drum 21 Drive apparatus 22 Output shaft 23 Spring 24 Drive gear 25 Drum gear 40 Frame member 50 Plate spring part

Claims (8)

  An apparatus main body including a driving device and a driving gear for transmitting a driving force from the driving device; and a photosensitive drum including a driven gear that is mounted on the apparatus main body and meshed with the driving gear. The drive gear and the driven gear mesh with each other by driving the drive device and slightly rotating the drive gear after the photosensitive drum is mounted on the apparatus main body. Forming equipment.   The drive gear is movable along the moving direction of the photosensitive drum, and the apparatus main body includes a biasing member that biases the driving gear in a direction opposite to the mounting direction of the photosensitive drum. The image forming apparatus according to claim 1.   When the driving gear and the driven gear are in contact with each other when the photosensitive drum is mounted on the apparatus main body, the driving gear is moved by the further mounting operation of the photosensitive drum to the apparatus main body. The image forming apparatus according to claim 2, wherein the image forming apparatus is pushed against a biasing force of the biasing member.   The said drive device is a motor fixed to the flame | frame of the said apparatus main body, Comprising: The said drive gear is attached to the output shaft of this motor so that sliding is possible to an axial direction. Image forming apparatus.   5. A key extending substantially over the entire length of the output shaft is fixed to the output shaft, and the drive gear can be rotated together with the output shaft at any position of the output shaft by the key. Image forming apparatus.   The image forming apparatus according to claim 4, wherein the biasing member is a coil spring and is wound around the output shaft between the drive gear and the frame.   5. The image according to claim 4, wherein a shaft hole is formed in the frame, and a shaft of the photosensitive drum is inserted into the shaft hole in a state where the photosensitive drum is mounted on the apparatus main body. Forming equipment.   2. The image forming apparatus according to claim 1, wherein the slight rotation of the drive gear is performed in an initialization step of the image forming apparatus.

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