JP2007271859A - Drive device and drive method for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive device and method capable of preventing a transfer belt from partially bending even if times taken to make the rotating speeds of motors constant from the start of them are varied. <P>SOLUTION: The drive device that rotates a plurality of photoreceptor drums 71B, 71Y, 71C, and 71M disposed in contact with the circumferential face of the transfer belt 73 includes: motors 2 as rotating source for the corresponding photoreceptor drums 71; drive force transmitting units 3; and control sections 4. The drive force transmitting units 3 transmit drive forces to the rotation shafts of the corresponding photoreceptor drums 71 from the corresponding motors 2. The control sections 4 control the timings of starting the corresponding motors 2B, 2Y, 2C and 2M so that the rotating speeds of the photoreceptor drums 71B, 71Y, 71C and 71M, disposed on the downstream side of transfer belt 73 in its rotating direction, become constant in that order. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving device used in an image forming apparatus, and more particularly, to a driving device and a driving method for driving a plurality of image carriers in contact with an outer peripheral surface of an endless belt member.

  As a color image forming apparatus such as a color printer or a color copying machine, a toner image is formed on the surface of a photosensitive drum corresponding to four colors of black, yellow, cyan and magenta, and these toner images are transferred onto a transfer belt in a multiple transfer manner. Then, there is a so-called tandem type color image forming apparatus in which this is transferred to a recording sheet and fixed. In the tandem type color image forming apparatus, the photosensitive drums for the respective color components are disposed in contact with the transfer belt. The tandem color image forming apparatus has a driving device for rotating the driven devices such as the respective photosensitive drums and the transfer belt. Some drive devices include a motor as a rotational drive source and a transmission device that transmits the rotation of the motor to the driven device.

In general, a driving device is provided for each driven device, and controls the operation of a motor in synchronization with the operation of a motor of another driving device. As such a drive device, for example, a device that synchronizes the rotation start and end operations of a plurality of motors (Patent Document 1), and a device that adjusts the rotation speed of each motor to the same speed are known (patents). Reference 2).
Japanese Patent Laid-Open No. 10-42593 Japanese Patent Laid-Open No. 10-186852

  By the way, the time from the start of each motor until the rotational speed becomes constant is affected by the load applied to the motor, the tolerance of the diameter, and the like. In particular, in a tandem color image forming apparatus, if the load applied to the motor as the rotational drive source for each photosensitive drum is different, the time from when each motor is started until the rotational speed becomes constant varies. Arise. In this case, since the time from when each photosensitive drum starts to rotate until the rotational speed becomes constant varies, the transfer belt in contact with each photosensitive drum is locally bent. However, as in Patent Documents 1 and 2, it is difficult to prevent the occurrence of local deflection in the transfer belt even if the operation of the motor is synchronized with the operation of the motor of another driving device.

  Therefore, the present invention provides a driving device and a driving method that can prevent local bending of the transfer belt even when the time from when each motor is started until the rotational speed becomes constant differs for each motor. I will provide a.

  In order to solve the above-described problems, the first aspect of the present invention rotates a plurality of image carriers that are in contact with the outer peripheral surface of an endless belt member, drives a motor as a rotation drive source of each image carrier, A drive device including a force transmission unit and control means is provided. The driving force transmission unit transmits the driving force from the motor to the rotation shaft of the image carrier. The control means controls the start timing for starting the motor so that the rotation speed becomes constant in order from the image carrier located on the downstream side in the rotation direction of the endless belt member.

  The time from when the motor is started until the rotational speed becomes constant is affected by the load applied to the motor and the tolerance of the diameter. Specifically, in a tandem image forming apparatus in which a plurality of image carriers are in contact with a transfer belt, each motor is started when the load applied to the motor for rotating each image carrier is different. After that, the time until the rotation speed becomes constant varies. In this case, since the time from when each image carrier starts to rotate until the rotational speed becomes constant varies, the transfer belt is locally bent. However, this drive device controls the rotation of the motor so that the rotation speed is constant in order from the image carrier on the downstream side in the rotation direction of the transfer belt. Then, a force to pull the transfer belt to the downstream side in the rotation direction is applied to the transfer belt in order from the downstream side in the rotation direction of the transfer belt. Therefore, the phenomenon that the transfer belt is bent can be prevented.

  Invention 2 is the invention 1, wherein the control means measures a time from when the motor is activated until the rotation speed of the motor becomes constant, and determines the activation timing based on the measured time. A drive device is provided.

  As a result, even if the time until the rotational speed of the motor becomes constant due to the influence of the motor load, diameter tolerance, etc. differs for each motor, the drive device is surely connected downstream in the rotation direction of the transfer belt. The rotation speed can be made constant in order from the image carrier located at the position.

  A third aspect of the present invention further includes a storage unit that stores the determined start timing in the second aspect, and the control unit starts the motor based on the start timing stored in the storage unit. A drive device is provided.

  The stored start timing is determined so that the rotation speed is constant in order from the image carrier located downstream in the rotation direction of the transfer belt, based on the time until the rotation speed of each motor becomes constant. Information. Therefore, the driving device can reliably prevent the phenomenon that the transfer belt is bent.

In order to solve the above-mentioned problem, the invention 4 is a method for rotationally driving a plurality of image carriers that are in contact with the outer peripheral surface of an endless belt member, and includes the following steps: A driving method is provided.
◎ Step of starting a motor as a rotational drive source of each image carrier ◎ Step of measuring a period from the start of the motor until the rotational speed of the motor becomes constant ◎ Based on the measured period, A step of determining a timing for starting the motor so that the rotation speed becomes constant in order from the image carrier located on the downstream side in the rotation direction of the endless belt member. A step of stopping the rotation of the motor. Starting the motor at the determined timing;

  It is assumed that the endless belt member is a transfer belt. When the motor is started by this driving method, a force for pulling the transfer belt member downstream in the rotation direction is applied in order from the downstream side in the rotation direction of the transfer belt member. Therefore, the phenomenon that the transfer belt member bends can be prevented.

  According to the drive device or the drive method of the present invention, even if the time from when each motor is started until the rotational speed becomes constant differs from one motor to another, the occurrence of local deflection in the transfer belt is prevented. be able to.

<Embodiment>
FIG. 1 is a diagram showing a cross-sectional configuration of a driving device 1 according to the present embodiment and connection with peripheral devices. 1 is connected to an image forming apparatus 7, and drives each photosensitive drum 71 (corresponding to an image carrier) provided in the image forming apparatus 7 as shown in FIG. Used as a device for

  The image forming apparatus 7 is a tandem color image forming apparatus, and as shown in FIG. 2, photosensitive drums 71B, 71Y, 71C, and 71M (hereinafter, referred to as black, yellow, cyan, and magenta). In some cases, the photosensitive drum 71 may be referred to) and a transfer device 72. The photosensitive drums 71B, 71Y, 71C, 71M for the respective colors are arranged along the outer peripheral surface in order from the downstream side in the rotation direction of a transfer belt 73 (corresponding to an endless belt member), which will be described later. It is touched. The transfer device 72 includes a transfer belt 73, a driving roller 74a, and a driven roller 74b. The transfer belt 73 is looped between the drive roller 74a and the driven roller 74b. The drive roller 74a is rotationally driven by a drive device different from the drive device 1 for driving the photosensitive drums 71B, 71Y, 71C, 71M.

(1) Configuration of Drive Device As shown in FIGS. 1 and 4, the drive device 1 includes motors 2B, 2Y, 2C, and 2M (hereinafter referred to as rotational drive sources) for the photosensitive drums 71B, 71Y, 71C, and 71M. A drive unit 3B, 3Y, 3C, 3M (hereinafter simply referred to as drive force transmission unit 3), a control unit 4 and a storage unit 5;

  The motors 2B, 2Y, 2C, 2M are provided corresponding to the photosensitive drums 71B, 71Y, 71C, 71M. Examples of the motor 2 include a DC (Direct-Current) motor that rotates when a current is applied.

  The driving force transmission units 3B, 3Y, 3C, 3M are for transmitting the driving force of the motors 2B, 2Y, 2C, 2M to the rotation shafts of the photosensitive drums 71B, 71Y, 71C, 71M, respectively. Similar to the motor 2, it is provided corresponding to each of the photosensitive drums 71B, 71Y, 71C, 71M. As shown in FIGS. 1 and 3, the driving force transmission unit 3 includes a motor rotating shaft 31, a plurality of planetary rollers 32, a ring 33, a carrier roller 34, an output shaft 35, a sensor 36, and a fixed body 37.

  The motor rotation shaft 31 outputs the rotation of the motor 2 to the outside. The plurality of planetary rollers 32 are positioned in a state of being pressed between the outer peripheral surface of the motor rotating shaft 31 and the inner peripheral surface of the ring 33. In the present embodiment, the case where there are three planetary rollers 32 is taken as an example. The edge of each planetary roller 32 is formed of an elastic body such as rubber or resin. The ring 33 is positioned so as to surround the three planetary rollers 32 and is in contact with each planetary roller 32 on the inner peripheral surface. The carrier roller 34 is located on the opposite side of the motor 2 when viewed from the planetary roller 32, and is connected to the planetary roller 32 by a rotation shaft 32 a of the planetary roller 32. The carrier roller 34 is connected to the output shaft 35 via a bearing 35 a located at a part of the fixed body 37. The edge of the carrier roller 34 is formed by a magnet 34a. The output shaft 35 outputs the rotation of the carrier roller 34 to the outside, specifically, to the rotation shaft of the photosensitive drum 71 on the same axis as the motor rotation shaft 31. The sensor 36 is located on the inner peripheral surface of the fixed body 37, and detects this when the rotation speed of the carrier roller 34 becomes constant. In the following description, the sensors 36 provided in the driving force transmission units 3B, 3Y, 3C, and 3M may be referred to as sensors 36B, 36Y, 36C, and 36M. The fixed body 37 is located outside the motor 2 and surrounds the motor rotating shaft 31, the three planetary rollers 32, the ring 33, the carrier roller 34, and the sensor 36.

  The control unit 4 is located outside the motor 2 and the fixed body 37. 1 and 4, the control unit 4 includes motors 2B, 2Y, 2C, and 2M, sensors 36B, 36Y, 36C, and 36M, the storage unit 5, and the photosensitive drums 71B in the image forming apparatus 7. , 71Y, 71C, 71M, and performs overall drive control of the motors 2B, 2Y, 2C, 2M. The configuration of the control unit 4 will be described later.

  As shown in FIG. 4, the storage unit 5 stores an activation timing table 5a. 5 and 7 are conceptual explanatory diagrams of the activation timing table 5a stored in the storage unit 5. FIG. The start timing table 5a shown in FIGS. 5 and 7 stores the name of the motor and the start timing as one code. The activation timing is a timing when the control unit 4 activates the motors 2B, 2Y, 2C, and 2M. For example, in the activation timing table 5a of FIG. 5, the activation timing for activating the motor 2Y 1 msec after the activation of the motor 2B is stored.

(2) Operation of Driving Force Transmission Unit Here, the operation of the driving force transmission unit 3 will be briefly described with reference to FIG.

  The motor rotation shaft 31 rotates in the rotation direction of the motor 2. Then, the three planetary rollers 32 revolve around the motor rotation shaft 31 in the same direction as the rotation direction of the motor rotation shaft 31 along the inner peripheral surface of the ring 33. Further, each planetary roller 32 rotates about the rotation shaft 32 a of each planetary roller 32 in the direction opposite to the rotation direction of the motor rotation shaft 31. The carrier roller 34 rotates in conjunction with the revolution of the planetary roller 32. That is, the carrier roller 34 rotates in the same direction as the rotation direction of the motor rotation shaft 31. At this time, the carrier roller 34 rotates at a speed at which the rotation of the motor rotating shaft 31 is decelerated by the rotation of the planetary roller 32.

(3) Configuration of Control Unit Next, the configuration of the control unit 4 will be described. As shown in FIG. 4, the control unit 4 includes motor drive control units 41B, 41Y, 41C, and 41M (hereinafter simply referred to as a motor drive control unit 41), and measurement units 42B, 42Y, 42C, and 42M (hereinafter referred to as “motor drive control units 41”). , And may be simply referred to as a measurement unit 42) and a timing determination unit 43.

(3-1) Motor Drive Control Unit The motor drive control unit 41 controls driving of the motor 2. Specifically, the motor drive control unit 41 controls driving of the motor 2 based on time information from a timer (not shown) so that the motor 2 can be started based on the start timing table 5a of the storage unit 5. The drive control signal is generated and transmitted to the motor 2.

(3-2) Measuring unit The measuring unit 42 measures the time from when the motor 2 is started until the rotational speed of the motor 2 becomes constant based on the drive control signal and the signal detected and output by the sensor 36. .

(3-3) Timing Determination Unit The timing determination unit 43 is a photosensitive drum positioned on the downstream side in the rotation direction of the transfer belt 73 based on the times measured by the measurement units 42B, 42Y, 42C, and 42M. The starting timings of the motors 2B, 2Y, 2C, and 2M are determined so that the rotational speed becomes constant in order from 71B, 71Y, 71C, and 71M. Then, the timing determination unit 43 stores the determined activation timing in the activation timing table 5a of the storage unit 5.

(4) Operation of Drive Device FIGS. 6 and 8 are timing charts for explaining the operation of the control unit 4. The drive control signals of the motors 2B, 2Y, 2C, and 2M and the sensors 36B, 36Y, and 36C are illustrated. , 36M output a lock signal. Here, the drive control signals in FIGS. 6 and 8 represent motor stop as “0” and drive as “1”. The lock signal represents “0” when the rotation speed of the carrier roller 34 is constant at a predetermined speed, and “1” otherwise.

  First, when the power source of the image forming apparatus 7 is turned on and the image forming apparatus 7 is activated, the motor drive control units 41B, 41Y, 41C, and 41M are driven by the motors 2B, 2Y, 2C, and 4C based on the activation timing table 5a of FIG. Activate 2M. Specifically, first, the motor drive control unit 41B activates the motor 2B. Next, the motor drive control units 41Y, 41C, and 41M start the motor 2Y after the elapse of 1 msec from the activation of the motor 2B, the motor 2C after the elapse of 2 msec, and the motor 2M after the elapse of 3 msec, respectively. Each measurement unit 42B, 42Y, 42C, 42M starts monitoring the drive control signal and the lock signal. The transfer belt 73 starts to rotate based on the activation of the image forming apparatus 7.

  When the rotation of the motor 2 becomes constant at a predetermined speed, the rotation speed of the carrier roller 36 also becomes constant. Then, the sensor 36 outputs a lock signal “0”.

  Each measurement unit 42B, 42Y, 42C, 42M is based on the drive control signal and the lock signal, the time TB, TY, TC, the time from when the motors 2B, 2Y, 2C, 2M are started until the rotational speed becomes constant. Measure each TM. Here, the times TB, TY, TC, and TM in the present embodiment are assumed to be 4 msec, 2 msec, 6 msec, and 5 msec, respectively, as shown in FIG.

  Next, the timing determination unit 43 is a photoreceptor located downstream in the rotation direction of the transfer belt 73 based on the times TB, TY, TC, and TM measured by the measurement units 42B, 42Y, 42C, and 42M. Starting timings for starting the motors 2B, 2Y, 2C, and 2M are determined so that the rotation speed is constant in order from the drums 71B, 71Y, 71C, and 71M. That is, as shown in FIG. 8, the timing determination unit 43 activates each motor 2B, 2Y, 2C, 2M so that the lock signal of each motor 2B, 2Y, 2C, 2M falls in this order every 1 msec. Adjust the timing. More specifically, the timing determination unit 43 first determines the timing at which the lock signals of the motors 2B, 2Y, 2C, and 2M fall, and the times TB, TY, TC, and TM are moved backward from that timing. By taking this, the start timing of each motor 2B, 2Y, 2C, 2M is determined. The timing determination unit 43 overwrites the start timings of the respective motors 2B, 2Y, 2C, and 2M determined in this way on the start timing table 5a of the storage unit 5 (FIG. 7).

  When the power of the image forming apparatus 7 is turned off, the drive control units 41B, 41Y, 41C, and 41M output a motor drive control signal “0” to the motors 2B, 2Y, 2C, and 2M. Thereby, each motor 2B, 2Y, 2C, 2M stops rotation. Also, the transfer belt 73 stops rotating when the power of the image forming apparatus 7 is turned off.

  When the power of the image forming apparatus 7 is turned on again, the transfer belt 73 starts to rotate. The motor drive control units 41B, 41Y, 41C, and 41M start up the motors 2B, 2Y, 2C, and 2M based on the start timing table 5a of FIG. Specifically, the motor drive control units 41B and 41C first activate the motors 2B and 2C, and then the motor drive control unit 41M activates the motor 2M 2 msec after the motors 2B and 2C are activated. The motor drive control unit 41Y activates the motor 2Y 3 msec after the motors 2B and 2C are activated.

  Thereby, as shown in FIG. 8, the rotational speeds of the motors 2B, 2Y, 2C, and 2M are constant in this order. Accordingly, the rotational speeds of the photosensitive drums 71B, 71Y, 71C, and 71M are also constant in this order.

(5) Effect The driving device 1 is configured so that the rotational speeds of the motors 2B, 2Y, 2C, and 2M are constant in order from the photosensitive drums 71B, 71Y, 71C, and 71M on the downstream side in the rotation direction of the transfer belt 73. Control the rotation. Then, a force to pull the transfer belt 73 to the downstream side in the rotation direction is applied to the transfer belt 73 in order from the downstream side in the rotation direction of the transfer belt 73. Therefore, the phenomenon that the transfer belt 73 is bent can be prevented.

<Other embodiments>
(A) In the above-described embodiment, the case where the motor drive control unit and the measurement unit are provided corresponding to each photosensitive drum is described, but the present invention is not limited to this. The motor drive control unit and the measurement unit are provided one by one as long as the drive control of each motor and the measurement of the time from when each motor is started until the rotation speed becomes constant can be integrated. Also good.

  (B) In the above embodiment, the control unit controls each motor so that the start-up and rotation speed are constant every 1 msec, but the start-up interval and the rotation speed of each motor are constant. Not.

  The driving device and the driving method of the present invention include a plurality of photosensitive drums on a transfer belt among image forming apparatuses such as a copying machine, a printer, and a facsimile machine, and a multifunction machine having a scanner function in addition to these functions. It can be applied as an apparatus and method for controlling the rotation of a plurality of photosensitive drums in an apparatus in contact with the apparatus.

The figure which showed the cross-sectional structure of the drive device, and the connection with the peripheral device. 1 is a schematic diagram of an image forming apparatus in which a driving device is used. III-III sectional view taken on the line of a drive device. The block diagram which showed the peripheral structure connected with the function structure of the control part, and the control part. The conceptual explanatory drawing of the starting timing table which the memory | storage part memorize | stored first. The timing chart when a control part starts a motor based on the starting timing table of FIG. The conceptual explanatory drawing of the starting timing table after a control part determines starting timing. The timing chart when a control part starts a motor based on the starting timing table of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive device 2 Motor 3 Driving force transmission unit 4 Control part 5 Memory | storage part 5a Starting timing table 32 Planetary roller 34 Carrier roller 35 Output shaft 36 Sensor 37 Fixed body

Claims (4)

A drive device that rotationally drives a plurality of image carriers abutted on the outer peripheral surface of an endless belt member,
A motor as a rotational drive source for each image carrier;
A driving force transmission unit that transmits a driving force from the motor to the rotation shaft of the image carrier;
Control means for controlling the start timing for starting the motor so that the rotational speed is constant in order from the image carrier located on the downstream side in the rotational direction of the endless belt member;
Including a driving device.   2. The driving device according to claim 1, wherein the control unit measures a time from when the motor is activated until the rotation speed of the motor becomes constant, and determines the activation timing based on the measured time. . And further comprising storage means for storing the determined activation timing,
The drive unit according to claim 2, wherein the control unit starts the motor based on the start timing stored in the storage unit. A driving method of an image carrier for rotationally driving a plurality of image carriers abutted on the outer peripheral surface of an endless belt member,
Starting a motor as a rotational drive source of each image carrier;
Measuring a period from when the motor is started until the rotational speed of the motor becomes constant;
Determining a timing for starting the motor based on the measured period so that the rotation speed is constant in order from the image carrier located downstream in the rotation direction of the endless belt member; ,
Stopping the rotation of the motor;
Starting the motor at the determined timing;
A method for driving an image carrier.

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