JP2013160972A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce unpleasant noise to operators working around an image forming apparatus.SOLUTION: A down time from when output of a control signal to a main motor 70 is stopped to when the main motor 70 actually stops is determined in advance. Control means 60 turns on flapper solenoids 84a to 84d during the down time so as to block transmission of a drive force F1 to developing rollers 241a to 241d.

Description

  The present invention relates to an image forming apparatus including a clutch that transmits a driving force to a rotating body or blocks the transmission.

  In conventional image forming apparatuses, in order to reduce the discomfort that peripheral workers receive from operating noise, the impact sound when energizing a plurality of electromagnetic clutches during continuous feeding and the recording medium to the registration roller There is one that matches the timing of abutting (for example, see Patent Document 1).

  Incidentally, in addition to the electromagnetic clutch, there is a clutch using a flapper solenoid (hereinafter referred to as a clutch mechanism). Unlike the electromagnetic clutch, the clutch mechanism generates an impact sound both when it is on and when it is off.

  In many cases, an image forming apparatus includes a plurality of motors that are stopped at different timings under the control of a control unit. Specifically, the fixing motor is stopped after completion of paper discharge. On the other hand, the so-called main motor rotates for a certain time after the fixing motor stops.

JP 2008-197233 A

  However, when the clutch mechanism is applied to the image forming apparatus, if the clutch mechanism is designed to be turned off after all the motors are stopped, the impact sound of the clutch mechanism is generated in the absence of motor operation noise. End up. In this case, there is a problem that only the impact sound is prominently heard by the peripheral worker, and the peripheral worker feels annoying.

  Therefore, an object of the present invention is to reduce annoying noise in an image forming apparatus that employs a clutch that generates an impact sound when it is off, such as a clutch mechanism.

  In order to achieve the above object, one aspect of the present invention is an image forming apparatus, which includes a plurality of rotating bodies, a plurality of motors that apply driving force to the plurality of rotating bodies, and stop at different timings; A clutch mechanism that transmits / cuts a driving force from a motor that stops last (hereinafter referred to as a final motor) among the plurality of motors and generates an impact sound at least when the driving force is cut off; Control means for interrupting transmission of driving force by the clutch mechanism before the motor stops.

  According to the said form, since it can prevent that only a clutch impact sound protrudes and hears to a surrounding worker, it becomes possible to reduce an annoying sound.

1 is a schematic diagram illustrating an internal configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a schematic diagram illustrating a block configuration of a drive mechanism of the image forming apparatus. FIG. 2 is a schematic diagram illustrating a structure of a drive mechanism of the image forming apparatus. FIG. It is a schematic diagram which shows the structure of a planetary gear mechanism. (A) is a timing chart showing general motor stop control, and (B) is a timing chart showing motor stop control according to the present invention. It is a schematic diagram which shows the block structure of the drive mechanism which concerns on a modification.

  Hereinafter, an image forming apparatus according to an embodiment of the present disclosure will be described with reference to the drawings. In the drawing, an X axis, a Y axis, and a Z axis indicate a left-right direction (lateral direction), a front-rear direction (depth direction), and a vertical direction (height direction) of the image forming apparatus. In addition, lowercase letters a, b, c, and d following the reference numerals are subscripts representing yellow (Y), magenta (M), cyan (C), and black (K). For example, the photoconductor drum 21a means the photoconductor drum 21 for yellow.

(Schematic configuration of image forming apparatus)
In FIG. 1, the image forming apparatus is, for example, a tandem type full-color MFP (Multifunction Peripheral) adopting an electrophotographic system.

  The image forming apparatus includes an intermediate transfer belt 11 at a substantially central portion inside the main body. The intermediate transfer belt 11 is wound around the outer periphery of the roller 12, the tension roller 13, and the guide rollers 14 and 15, and is driven to rotate counterclockwise.

  Immediately below the intermediate transfer belt 11, the image forming units 2a to 2d are arranged in this order from left to right. The image forming units 2a to 2d include photosensitive drums 21a to 21d. Around the photosensitive drums 21a to 21d, for example, chargers 22a to 22d and developing devices 24a to 24d are arranged in this order along the rotation direction. A laser scanning optical system 23 is disposed below the image forming units 2a to 2d.

  Further, primary transfer rollers 30a to 30d are provided at positions facing the respective photosensitive drums 21a to 21d with the intermediate transfer belt 11 interposed therebetween. Further, a secondary transfer roller 16 is pressed against the roller 12 with the intermediate transfer belt 11 interposed therebetween. As a result, a nip as a secondary transfer region 17 is formed between the secondary transfer roller 16 and the intermediate transfer belt 11.

  A paper feed cassette 91 is detachably disposed at the lower stage of the image forming apparatus main body. The paper P stacked in the paper feed cassette 91 is pulled out one by one by a rotating paper feed roller 92 and sent out to a transport path R indicated by a dotted arrow.

  The conveyance path R extends from the paper feed cassette 91 to the paper discharge tray 98 through the nip portion of the timing roller pair 94, the secondary transfer region 17, the fixing unit 4, and the paper discharge roller pair 50. The paper P sent out from the paper feed cassette 91 is conveyed to the timing roller pair 94 and is sent out to the secondary transfer area 17 at a predetermined timing.

  The fixing unit 4 includes a fixing roller 41 and a pressure roller 42. The paper P sent out from the secondary transfer region 17 is introduced into the nip between these rollers 41 and 42. The fixing roller 41 heats the toner image on the paper P passing through the nip while rotating. At the same time, the pressure roller 42 presses the paper P while rotating.

(Schematic operation of the image forming apparatus)
Next, a schematic operation of the image forming apparatus will be described. In the image forming apparatus, the chargers 22a to 22d charge the rotating photosensitive drums 21a to 21d. In the laser scanning optical system 23, the Y, M, C, and K light emitting elements are driven by digital image signals of corresponding colors. In response to this, a light beam modulated by the digital image signal is emitted from each light emitting element.

  The light beams of the respective colors are irradiated on the peripheral surfaces of the photosensitive drums 21a to 21d via a polygon mirror, a scanning lens, and the like, and electrostatic latent images of the respective colors are formed. Each of the developing devices 24a to 24d includes developing rollers 241a to 241d, which are typical examples of predetermined rotating bodies. The developing devices 24a to 24d develop the electrostatic latent images formed on the peripheral surfaces of the photosensitive drums 21a to 21d to form toner images of the respective colors. During such development processing, each of the developing rollers 241a to 241d is rotated by a driving force F1, which will be described later, and supplies toner to the peripheral surfaces of the photosensitive drums 21a to 21d.

  The toner images of Y, M, C, and K are primarily transferred so as to overlap each other on the intermediate transfer belt 11 that rotates counterclockwise in the drawing by the action of the primary transfer rollers 30a to 30d. As a result, a composite toner image is formed on the intermediate transfer belt 11. The composite toner image is conveyed to the secondary transfer region 17 by the rotation of the intermediate transfer belt 11.

  Further, the paper P sent out from the paper feed cassette 91 to the transport path R is sent out to the secondary transfer area 17 by the timing roller pair 94 in accordance with the timing when the composite toner image reaches the secondary transfer area 17. In addition, a voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 16. As a result, the composite toner image is secondarily transferred from the intermediate transfer belt 11 to the paper P in the secondary transfer region 17.

  The sheet P on which the composite toner image has been transferred is introduced into the nip of the fixing unit 4 through the conveyance path R, and after being fixed, is discharged from the discharge roller pair 50 to the discharge tray 98.

(About drive mechanism)
In addition to the above configuration, the image forming apparatus includes a control unit 60, a main motor 70, drive mechanisms 80a to 80d, and a fixing motor 71 as shown in FIG.

  The control means 60 includes a CPU and a main memory. The control unit 60 controls each component of the image forming apparatus. What is important in this embodiment is stop control of the main motor 70 and the fixing motor 71 as typical examples of a plurality of motors.

  The main motor 70 and the fixing motor 71 rotate under the control of the control means 60 and generate driving forces F1 and F2. The driving force F1 is transmitted to the developing rollers 241a to 241d through the driving mechanisms 80a to 80d. The driving force F1 is further transmitted to the photosensitive drums 21a to 21d, the intermediate transfer belt 11 and the like through gears and the like. The driving force F <b> 2 is transmitted to the fixing unit 4 and the paper discharge roller pair 50.

  Here, the drive mechanisms 80a to 80d will be described in detail. As shown in FIGS. 2 and 3, the drive mechanisms 80a to 80d include input gears 81a to 81d, clutch mechanisms 82a to 82d, and output gears 83a to 83d. The clutch mechanisms 82a to 82d have flapper solenoids 84a to 84d, ratchets 85a to 85d, and planetary gear mechanisms 86a to 86d. The planetary gear mechanisms 86a to 86d include carriers 87a to 87d, three planetary gears 88a to 88d, sun gears 89a to 89d, shafts 90a to 90d, and internal teeth as illustrated in FIG. And gears 91a to 91d.

  The flapper solenoids 84 a to 84 d are turned on / off under the control of the control means 60. At the on / off time, each of the flapper solenoids 84a to 84d emits an impact sound due to driving of a built-in solenoid.

  In the drive mechanisms 80a to 80d, when the flapper solenoids 84a to 84d are on, the unit load is larger than the ratchet fixing force. In this case, the driving force F1 transmitted from the main motor 70 to the input gears 81a to 81c is transmitted in the order of the carrier of the planetary gear mechanisms 86a to 86d → the planetary gear → the sun gear → the shaft. In this case, the ratchets 85a to 85d rotate, and the driving force F1 is not transmitted to the output gears 83a to 83d. As described above, the driving mechanisms 80a to 80d block the transmission of the driving force F1 to the developing rollers 241a to 241d.

  On the other hand, when the flapper solenoids 84a to 84d are off, the ratchet fixing force is greater than the unit load. In this case, the driving force F1 to the input gears 81a to 81d is transmitted in the order of the carrier of the planetary gear mechanisms 86a to 86d → the planetary gear → the internal gear, and the output gears 83a to 83d rotate. A driving force F1 is transmitted to the developing rollers 241a to 241d through the output gears 83a to 83d. By this driving force F1, the developing rollers 241a to 241d rotate.

(Motor stop control)
For example, as shown in FIG. 5 (A), when all the motors including the main motor and the fixing motor are stopped, if the driving force transmission to the developing roller is interrupted using the flapper solenoid, the peripheral worker is notified to the flapper. There was a problem that the impact sound of the solenoid was protruding.

  In order to solve such a problem, in the image forming apparatus, as shown in FIG. 5B, stop control of the main motor 70 and the fixing motor 71 by the control means 60 is executed. In FIG. 5B, only the operation timings of the main motor 70, the fixing motor 71, and the clutch mechanisms 82a to 82d related to the stop control are shown.

  In FIG. 5B, the main motor 70 is a typical example of the final motor, and stops at the end among all the motors including the fixing motor 71. Specifically, the control unit 60 stops outputting the control signal to the main motor 70 at a predetermined timing after the image formation (time t0 in FIG. 5A). Further, the control unit 60 stops outputting the control signal to the fixing motor 71 at the timing (time t1) when the paper P passes through the paper discharge roller pair 50. Here, the main motor 70 stops at time t3 after the stop of the fixing motor 71 (time t2) because of cleaning of the photosensitive drums 21a to 21d.

  Here, the stop time from the stop of the output of the control signal to the main motor 70 until the actual stop of the main motor 70 is determined in advance. The control means 60 turns on the flapper solenoids 84a to 84d during this stop time in order to cut off the transmission of the driving force F1 to the developer rollers 241a to 241d (time t4). Therefore, the impact sound of the flapper solenoids 84a to 84d is mixed with the operation sound of the main motor 70, so that it is difficult for the surrounding workers to hear. In the image forming apparatus, the harsh sound is reduced in this way.

(Modification)
Next, a modification of the present invention will be described with reference to FIG. In FIG. 6, the control means 60 incorporates at least monitoring means 61 for monitoring the back electromotive force of the main motor 70 in terms of software.

  The control means 60 turns off the flapper solenoids 84a to 84d when the back electromotive force obtained from the monitoring means 61 becomes a predetermined reference value or less. This reference value is determined in consideration of variations in the stop time of the main motor 70 itself and stop time errors due to differences in system speed. By this process, the control means 60 can reliably turn off the flapper solenoids 84a to 84d during the stop time of the main motor 70.

(Appendix)
In the description of the above embodiment and the modified examples, the example in which the plurality of motors are the main motor 70 and the fixing motor 71 and the final motor is the main motor 70 has been described. However, the present invention is not limited to this, and the plurality of motors and the final motor may be any motor as long as the motor is provided in the image forming apparatus.

  The image forming apparatus according to the present invention has an effect of reducing the harsh sound of surrounding workers, and is useful as a color printer, a copying machine, a copying machine or the like in addition to the MFP.

21a to 21d Photosensitive drums 24a to 24d Developer 23 Laser scanning optical system 4 Fixing unit 50 Paper discharge roller pair 60 Control means 61 Monitor means 70 Main motor 71 Fixing motor 80a to 80d Drive mechanism 82a to 82d Clutch mechanism 84a to 84d Flapper solenoid

Claims (3)

A plurality of rotating bodies;
A plurality of motors that apply driving force to the plurality of rotating bodies and stop at different timings;
A clutch mechanism that transmits / cuts a driving force from a motor that stops last (hereinafter referred to as a final motor) among the plurality of motors, and generates an impact sound at least when the driving force is cut off;
An image forming apparatus comprising: control means for interrupting transmission of driving force by the clutch mechanism before the final motor stops.   The image forming apparatus according to claim 1, wherein when the back electromotive force of the final motor becomes equal to or less than a predetermined reference value, the control unit interrupts transmission of driving force by the clutch mechanism.   The image forming apparatus according to claim 1, wherein the clutch mechanism includes a flapper solenoid.

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