JP2005328677A - Rotating body driving device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating body driving device that can always keep a torque margin of a stepping motor in an optimum state irrespective of a temperature in the device. <P>SOLUTION: A large diameter gear 3 made of a resin is mounted at the end of a driving shaft 20 of a photoreceptor drum 1. The rotation of a stepping motor 4 is transmitted to the driving shaft 20 via an output gear 5 and the large diameter gear 3 to drive the rotation of the drum 1. A temperature in the device is measured by a temperature sensor 6 arranged near the stepping motor 4. By controlling the drive current value of the stepping motor 4 based on temperature data, the torque margin of a driving means that drives the drum 1 is optimized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotating body driving device that drives a rotating body such as a photosensitive drum.

JP 2001-125436 A Japanese Patent Laid-Open No. 5-35060

  In image forming apparatuses, stepping motors are widely used as drive means for driving a photosensitive drum, a transfer belt (conveyance belt), and the like. Regarding the appropriate drive control of the stepping motor, for example, the above-mentioned Patent Document 1 detects the drive time of the chopping constant current based on the chopping control, and changes the value of the chopping constant current in response to the detected drive time. There has been disclosed a drive control device that is adapted to optimize the current value. Japanese Patent Application Laid-Open No. H10-228561 discloses a driving pulse generated by a stepping motor that drives a photosensitive member when the optical writing unit is not scanned.

  However, when a resin gear is present in the drive train from the stepping motor, the gear diameter increases due to linear expansion when the internal temperature becomes high, and therefore the gear backlash is eliminated and the drive transmission load increases. There was a problem that sometimes.

  On the other hand, when the inside of the machine becomes low temperature, the resin gear contracts, and there is a problem that the resistance load of the sliding portion having the inner diameter becomes large. Further, the torque of the stepping motor itself may vary depending on the temperature.

  An object of the present invention is to solve the above-mentioned problems in the conventional driving device and to provide a rotating body driving device that can always keep the torque margin of the stepping motor optimal regardless of the temperature in the device.

  According to the present invention, in the rotating body drive device using the stepping motor as the driving means for driving the rotating body according to the present invention, the temperature detecting means for detecting the temperature in the apparatus is provided, and the temperature detected by the temperature detecting means is set. This is solved by controlling the drive current value of the stepping motor based on the above.

  In addition, it is preferable that the rotating body is detachably provided on a rotating shaft driven by the stepping motor.

In addition, according to the present invention, the above problem is solved by an image forming apparatus including the rotating body driving device according to claim 1.
The rotating body is preferably an image carrier.
In addition, it is preferable that a plurality of the image carriers are provided to form a color image.

  In addition, it is preferable that the image carrier and an apparatus related to image formation disposed around the image carrier are integrated as a process cartridge, and the process cartridge is configured to be detachable from the apparatus main body.

Further, it is preferable that a plurality of the process cartridges are provided to form a color image.
Further, it is preferable that the rotating body is a driving roller of a conveying belt that conveys a recording medium.

  According to the rotating body driving device or the image forming apparatus of the present invention, the temperature detecting means for detecting the temperature in the apparatus is provided, and the driving current value of the stepping motor is controlled based on the temperature detected by the temperature detecting means. The torque margin of the stepping motor that drives the rotating body can be optimized, vibration and noise due to the large margin can be suppressed, and motor step-out due to the small margin can be prevented.

  With the configuration of the second aspect, since the rotating body is detachably provided on the rotating shaft driven by the stepping motor, the rotating body can be easily replaced.

  According to the configuration of the fourth aspect, since the rotating body is an image carrier, the torque margin of a stepping motor that drives the image carrier can be optimized, and image quality can be suppressed by suppressing vibration and speed unevenness of the image carrier. Can be prevented.

  According to the configuration of claim 5, since a plurality of image carriers are provided and a color image can be formed, the driving of the plurality of image carriers is optimized, and a color image with high quality can be obtained by suppressing color shift. Can do.

  According to the configuration of the sixth aspect, the image carrier and the apparatus related to image formation disposed around the image carrier are integrated as a process cartridge, and the process cartridge is configured to be detachable from the apparatus main body. Can be replaced.

  According to the configuration of the seventh aspect, since a plurality of process cartridges are provided and a color image can be formed, the plurality of process cartridges can be easily replaced, and the driving of the image carrier of each process cartridge is optimized, and the color A high-quality color image can be obtained while suppressing the shift.

  With the configuration of the eighth aspect, the driving of the conveyor belt can be optimized. In particular, in a configuration including a plurality of image carriers or a plurality of process cartridges, it is possible to prevent color misregistration by suppressing unevenness in the sheet conveyance speed and obtain a high-quality color image.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing an example of a rotating body driving device in which the present invention is applied to a driving device for driving a photosensitive drum of an image forming apparatus. In this figure, a front side plate 14 and a rear side plate 15 constituting the main body frame of the image forming apparatus are connected by stays 16 and 16. A main body bracket 17 is fixed to the outside (back side) of the rear plate 15. A front flange 18 and a back flange 19 are press-fitted into the photosensitive drum 1 and integrated with each other, and the drum unit 2 is configured by these. The front flange 18 and the back flange 19 are detachably fixed to the photosensitive member drive shaft 20 so that the drive shaft 20 and the drum unit 2 rotate together. The back flange 19 is detachably connected to the drive shaft 20 by connecting means 26 described later.

  A positioning member 22 is detachably fixed to the front plate 14 by a plurality of screws 21, and a front flange 18 is rotatably supported by the positioning member 22 via a bearing 23. The front end of the drive shaft 20 is detachably fitted to the front flange 18. The front flange 18 and the front portion of the drive shaft 20 pass through a hole formed in the front plate 14.

  The rear portion of the drive shaft 20 extends through the rear plate 15 and the main body bracket 17 and is rotatably supported by a pair of rolling bearings (not shown) held by a cylindrical holder 25. The holder 25 is detachably fixed to the rear plate 15 with screws. A large-diameter gear 3 that is a resin gear is attached to the back end of the drive shaft 20. A stepping motor 4 as a driving means is fixed to a main body bracket 17, and an output gear 5 fixed to the output shaft is meshed with the large-diameter gear 3 described above. The rotation of the stepping motor 4 is transmitted to the drive shaft 20 through the output gear 5 and the large diameter gear 3, and the rotation of the drive shaft 20 is transmitted to the back flange 19 through the connecting means 26, whereby the drum unit 2 rotates. Driven.

  FIG. 2 shows a state where the rear flange 19 of the drum unit 2 is detached from the drive shaft 20. As shown in FIG. 2, a separate flange 19 is press-fitted into the end opening of the photosensitive drum 1. A plurality of grooves 14 extending in the axial direction at a predetermined pitch in the circumferential direction are provided on the inner peripheral surface of the flange.

  On the other hand, a connecting means 26 including an engaging member 27 and a compression spring 28 is assembled to the drive shaft 20. The engaging member 27 is configured not to rotate with respect to the rotating shaft 20. On the drum-facing surface of the engaging member 27, a claw portion 29 that is disposed at a predetermined pitch in the circumferential direction corresponding to the groove 14 of the back flange 19 is formed, and the groove 14 and the claw portion 29 are formed. A coupling force is transmitted from the stepping motor 4 to the photosensitive drum 1 by coupling.

  By removing the positioning member 22 shown in FIG. 1 from the front plate 14, the drum unit 2 can be pulled out from the main body frame of the image forming apparatus. Further, the drum unit 2 can be assembled to the main body frame by the reverse operation, and the unit 2 can be fixed to the drive shaft 20. That is, the drum unit 2 can be attached to and detached from the drive shaft 20.

  As shown in FIG. 1, a temperature sensor 6 for measuring the in-machine temperature is provided in the vicinity of the stepping motor 4. The output of the temperature sensor 6 is sent to a CPU in a control unit (not shown), for example, a control unit of the image forming apparatus main body. In this example, as shown in the flowchart of FIG. 3, when there is a job request after setting the photosensitive drum (S1) (S2), the temperature inside the apparatus is measured by the temperature sensor 6 (S3). Based on the temperature information, the drive current value of the stepping motor 4 is set (S4), and the printing operation is started (S5).

  Thus, by controlling the drive current value of the stepping motor 4 based on the measured in-machine temperature, the torque margin of the drive means for driving the photosensitive drum 1 can be optimized. Therefore, vibration noise due to a large margin can be suppressed, and motor step-out due to a small margin can be prevented.

  4 and 5 are cross-sectional views showing two embodiments of the process cartridge of the image forming apparatus. The process cartridges 40 and 50 shown in these drawings are configured such that members and units relating to image formation disposed around the photosensitive drum 1 are integrally formed and can be attached and detached along the drive shaft 20. Is.

  The process cartridge 40 shown in FIG. 4 is a process cartridge in which a charging unit 7 for charging the photosensitive member, a cleaning unit 8 for cleaning the surface of the photosensitive member, and the like are integrated with the photosensitive drum 1 (drum unit 2) as a member related to image formation. Is configured.

  Further, the process cartridge 50 in FIG. 5 is configured by integrating the developing unit 9 and the like in addition to the charging unit 7 and the cleaning unit 8 with the photosensitive drum 1 (drum unit 2) as a member related to image formation. Is.

  The configuration of the drive system from the stepping motor 4 as the drive means to the drive shaft 20 and the configuration of the drum unit 2 including the front flange 18 and the back flange 19 are the same as the example described in FIGS. In the embodiment of the cartridge, not only the photosensitive drum 1 (drum unit 2) but also members and units arranged around the photosensitive member can be attached and detached along the drive shaft 20 (from the image forming apparatus main body) together with the process cartridge. There is a feature in the point.

  A temperature sensor 6 for measuring the in-machine temperature is provided in the vicinity of the stepping motor 4 that drives the photosensitive drum 1 of the process cartridges 40 and 50 (see FIG. 1). Then, by controlling the drive current value of the stepping motor 4 based on the in-machine temperature measured by the temperature sensor 6, the torque margin of the drive means for driving the photosensitive drum 1 can be optimized. Therefore, vibration noise due to a large margin can be suppressed, and motor step-out due to a small margin can be prevented.

Next, two examples of the image forming apparatus to which the present invention is applied will be described.
An image forming apparatus 100 shown in FIG. 6 includes a scanner unit 60 and is configured as a copying machine. In the copying machine 100, the photosensitive drum 1 is disposed at a substantially central portion of the apparatus main body. Around the photosensitive drum 1, devices related to image formation such as a charging unit 61, a developing unit 62, and a cleaning unit 63 are arranged. The document image read by the scanner unit 60 is guided to the photosensitive drum 1 via a mirror, a lens, or the like, and a latent image is formed on the photosensitive member. The latent image is visualized by applying toner from the developing means 62, and the toner image is transferred onto the paper fed from the paper feed unit 64. The paper carrying the toner image is sent to the fixing device 65, and after the toner image is fixed on the paper, it is discharged to the paper discharge tray 66.

  In the copying machine 100 of this example, the configuration of the drive system from the stepping motor 4 as the driving means for driving the photosensitive drum 1 to the drive shaft 20 and the configuration of the drum unit 2 including the front flange 18 and the back flange 19 are as follows. 1 and 2, the photosensitive drum 1 (drum unit 2) can be attached and detached along the drive shaft 20 (from the image forming apparatus main body).

  Further, a temperature sensor 6 for measuring the temperature inside the machine is provided in the vicinity of the stepping motor 4 that drives the photosensitive drum 1 (see FIG. 1), and the stepping motor is based on the temperature inside the machine measured by the temperature sensor 6. By controlling the drive current value of 4, the torque margin of the drive means for driving the photosensitive drum 1 can be optimized. Therefore, vibration noise due to a large margin can be suppressed, and motor step-out due to a small margin can be prevented.

  In the image forming apparatus, the torque margin of the driving means for driving the photosensitive drum 1 can be optimized, so that the image quality of the toner image formed on the photosensitive drum can be improved.

  The image forming apparatus 200 shown in FIG. 7 is configured as a color printer. In the color printer 200, a transfer conveyance belt 71 is disposed obliquely at a substantially central portion of the apparatus main body. Four image forming units 70M, 70C, 70Y, and 70Bk for magenta (M), cyan (C), yellow (Y), and black (Bk) are arranged in order from the bottom along the upper running side of the transfer conveyance belt 71. They are arranged side by side. Each image forming unit has the same configuration, and devices related to image forming such as a charging unit, a developing unit, and a cleaning unit are arranged around the photosensitive drum 1.

  An optical writing device 72 is provided obliquely above each of the color image forming units 70M, 70C, 70Y, and 70Bk. Laser light from the optical writing device 72 is applied to the photosensitive drum 1 between the charging unit and the developing unit. Irradiated.

  The transfer conveyance belt 71 is wound around a plurality of rollers such as a driving roller and a driven roller, and conveys the recording paper by electrostatically adsorbing it. In the loop of the transfer conveyance belt 71, a transfer brush as a transfer means is provided at a position facing the photosensitive drum 1 of each color image forming unit. An auxiliary roller is disposed in the vicinity of the transfer brush.

  The printing operation in the color printer 200 will be briefly described. In each color image forming unit 70, the surface of the photosensitive drum 1 is uniformly charged to a predetermined potential by a charging unit. Based on image data sent from a host machine such as a personal computer, the LD (laser diode) of the optical writing device 72 is driven to irradiate the polygon mirror with the laser beam, and the reflected light is passed through the cylinder lens or the like to the photosensitive drum 1. Leads up to form an electrostatic latent image. Toner is applied from the developing means to the latent image to form a toner image.

  On the other hand, a sheet designated as a transfer material is fed from the sheet feeding unit 73 and conveyed by the transfer conveyance belt 71. Each color toner image is transferred onto the paper from the photosensitive drum 1 of each color image forming unit 70, and a full color image is formed on the paper. In the case of monochrome printing, a toner image is formed only on the black image forming unit 70Bk and transferred onto the paper. The sheet on which the toner image has been transferred is separated from the transfer conveyance belt 71 and fixed by the fixing device 50. The sheet that has been fixed is discharged to a discharge tray 75 provided on the upper surface of the apparatus main body.

  Now, in the color printer 200 of this example, the configuration of the drive system from the stepping motor 4 as the drive means for driving the photosensitive drum 1 to the drive shaft 20 and the configuration of the drum unit 2 including the front flange 18 and the back flange 19 are as follows. 1 and 2, the photosensitive drum 1 (drum unit 2) can be attached and detached along the drive shaft 20 (from the image forming apparatus main body).

  Further, a temperature sensor 6 for measuring the temperature inside the machine is provided in the vicinity of the stepping motor 4 that drives the photosensitive drum 1 (see FIG. 1), and the stepping motor is based on the temperature inside the machine measured by the temperature sensor 6. By controlling the drive current value of 4, the torque margin of the drive means for driving the photosensitive drum 1 can be optimized. Therefore, vibration noise due to a large margin can be suppressed, and motor step-out due to a small margin can be prevented.

  In the image forming apparatus, the torque margin of the driving means for driving the photosensitive drum 1 can be optimized, so that the image quality of the toner image formed on the photosensitive drum can be improved. Further, in a color image forming apparatus having a plurality of photoconductors as in this example, it is possible to obtain a high-quality color image by suppressing color misregistration by optimizing the driving of each color photoconductor drum.

  In each color image forming unit 70, only the photosensitive drum 1 (drum unit 2) is not detachable along the drive shaft 20, but a photosensitive drum as in the process cartridge 40 or 50 described with reference to FIGS. A process cartridge including members and units related to image formation arranged around 1 may be used, and the process cartridge may be detachable along the drive shaft 20 (from the image forming apparatus main body).

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. The rotating body is not limited to the photosensitive drum, and the present invention can be applied to driving an appropriate rotating body such as a transfer drum, a photosensitive belt, or a driving roller such as a transfer belt.

  The control of the drive current value of the drive means according to the in-machine temperature increases (or decreases) the drive current value when the temperature rises, decreases (or increases) the drive current value when the temperature decreases, etc. Control corresponding to the configuration of each device may be performed. Of course, the configuration of the drive system, the configuration of the process cartridge, the configuration of each part of the image forming apparatus, and the like can be changed as appropriate.

1 is a configuration diagram illustrating an example of a rotating body driving device in which the present invention is applied to a driving device that drives a photosensitive drum of an image forming apparatus. FIG. 2 is a partial detail view showing a state where the photosensitive drum of FIG. 1 is detached from a drive shaft. It is a flowchart which shows control of the rotary body drive device of FIG. 1 is a cross-sectional configuration diagram illustrating an example of a process cartridge of an image forming apparatus. It is a section lineblock diagram showing other examples of a process cartridge. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus to which the present invention is applied. It is a cross-sectional block diagram which shows the other example of the image forming apparatus to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Drum unit 3 Large diameter gear 4 Stepping motor 5 Output gear 6 Temperature sensor 7 Charging means 8 Cleaning means 9 Developing means 19 Back flange 20 Photosensitive body drive shaft (rotating shaft)
40, 50 Process cartridge 70 Image forming unit 71 Transfer conveyance belt 100 Copier 200 Color printer

Claims (8)

In a rotating body driving device using a stepping motor as a driving means for driving the rotating body,
A rotating body driving apparatus comprising temperature detecting means for detecting a temperature in the apparatus, and controlling a driving current value of the stepping motor based on the temperature detected by the temperature detecting means. The rotator driving apparatus according to claim 1, wherein the rotator is detachably attached to a rotating shaft driven by the stepping motor. An image forming apparatus comprising the rotating body driving device according to claim 1. The image forming apparatus according to claim 3, wherein the rotating body is an image carrier. The image forming apparatus according to claim 4, wherein a plurality of the image carriers are provided to form a color image. 5. The apparatus according to claim 4, wherein the image carrier and an apparatus related to image formation disposed around the image carrier are integrated as a process cartridge, and the process cartridge is configured to be detachable from the apparatus main body. Image forming apparatus. The image forming apparatus according to claim 6, wherein a plurality of the process cartridges are provided to form a color image. The image forming apparatus according to claim 3, wherein the rotating body is a driving roller of a conveyance belt that conveys a recording medium.

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