JP2008113490A - Rotator drive controller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotator drive controller capable of easily deciding a suitable control gain that corresponds to a plurality of target speeds. <P>SOLUTION: A reference clock 1 is input into a speed discriminator part 2 corresponding to speed, and the speed discriminator part 2 outputs a command voltage, corresponding to the reference clock and an FG output obtained by measuring the rotation speed of a motor. A speed ratio calculating part 13 calculates the standard speed/a target speed from the standard speed and the target speed, to output these speeds. An integration amplifier part 3 integrates (smoothes) the outputs from the speed discriminator part 2 and the speed ratio calculating part 13 to set the gain of a control loop. A PWM oscillation part 4 PWM-controls the motor 6 by the set control gain and the motor 6 is driven at a desired speed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive control device that controls a rotating body to a plurality of target speeds and an image forming apparatus using the drive control device.

Japanese Patent No. 3559669 JP 2001-282046 A JP 2003-264989 A

  Photosensitive members and transfer belts in image forming apparatuses such as digital copying machines and laser printers are always driven at a constant speed. Usually, at least a speed discriminator method is used for motor control for controlling the driving motor. Speed control is used.

  For example, Japanese Patent Application Laid-Open No. 2004-228561 describes a servo motor that drives a fixing device and a sheet conveying unit before and after the fixing device by a control circuit including a speed discrete circuit.

  Japanese Patent Application Laid-Open No. H10-228561 describes a motor that drives a paper conveying unit, a photosensitive drum, a developing device, a fixing device, or the like with an ASIC including a speed discriminator.

  Patent Document 3 describes an image forming apparatus that uses a DC motor as a driving source for a photosensitive drum or a paper transport unit, and that controls the DC motor with an ASIC including a speed discriminator. .

  However, in each of the above patent documents, it is described that the motor is driven and controlled by at least a speed discriminator. However, when there are a plurality of target values such as a copying machine or a printer, these are dealt with. There is no description on how to determine the optimum control gain.

  In general, conventionally, gains corresponding to the respective speeds are obtained by trial and error, and there is a problem that it is not easy to determine an optimal control gain corresponding to a plurality of target speeds.

  Accordingly, an object of the present invention is a rotating body drive control device for controlling and driving a motor by at least speed control by a speed discriminator, and in a drive control system having a plurality of target speeds including standard speeds. Another object of the present invention is to provide a drive control device that can easily determine an optimal control gain corresponding to them.

  In addition, an image carrier (photosensitive belt, photosensitive drum, transfer belt, transfer drum, etc.) of an image forming apparatus is used by using a drive control device that can easily determine an optimal control gain corresponding to a plurality of target speeds. ), A transfer material conveyance belt drive system, an image reading apparatus, or the like. The object is to enable input / output of an image under a plurality of speed conditions under optimum conditions as well as a standard speed.

  According to the present invention, there is provided a drive control device having a plurality of target speeds including standard speeds, and the DC motor is controlled by speed control using a speed discriminator at least, and is driven by the motor. In the rotating body drive control device for controlling the body, the problem is solved by determining the gain of the feedback control in accordance with the ratio between the standard speed and the target speed.

  Further, the number of the control gains is set to be smaller than the number of the target speeds, and a gain smaller than the optimum gain calculated by the ratio of the standard speed to the target speed is selected from the set gains. It is preferable to use it.

  In addition, when the set gain includes a standard gain that is optimum for a standard speed and the target speed is a standard speed, it is preferable to use the standard gain as a control gain.

  Two control gains are set as the control gain, the standard gain that is optimal for the standard speed and the low gain that corresponds to the slowest target speed. If the target speed is equal to or higher than the standard speed, the standard gain is used. When the target speed is slower than the standard speed, it is preferable to use the low gain.

  Further, it is preferable that the gain of the feedback control is output using an operational amplifier, and the input resistance value of the operational amplifier is changed according to the ratio between the standard speed and the target speed.

The input resistance of the operational amplifier is preferably a variable resistance.
In addition, resistors having different resistance values that can be selected as input resistors of the operational amplifier are provided for the number of target speeds, and a resistor having a resistance value corresponding to the ratio between the standard speed and the target speed is selected from the resistance group. It is preferable to use it.

According to the present invention, the above problem is solved by an image forming apparatus including the rotating body drive control device according to any one of claims 1 to 7.
Further, it is preferable that the rotating body driven and controlled by the rotating body drive control device is an image carrier.

The image carrier is preferably a photosensitive drum.
The image carrier is preferably a photosensitive belt.
The image carrier is preferably an intermediate transfer drum.

The image carrier is preferably an intermediate transfer belt.
Further, it is preferable that the rotating body driven and controlled by the rotating body drive control device is a recording material carrier.

The recording material carrier is preferably a transfer drum.
The recording material carrier is preferably a transfer conveyance belt.
Also, it has a plurality of image carriers, and each color image formed on each image carrier is sequentially superimposed and transferred onto the image carrier or the recording material carried on the recording material carrier to form a color image It is preferable.

  Further, it is preferable that an image reading apparatus having a moving body that moves by mounting an optical member is provided, and the rotating body that is driven and controlled by the rotating body drive control device is a member that is related to driving of the moving body.

  According to the present invention, the subject is an image reading apparatus including the rotating body drive control device according to any one of claims 1 to 7, and includes a moving body that mounts and moves an optical member. The rotating body that is driven and controlled by the rotating body drive control device is solved by an image reading apparatus that is a member related to driving of the moving body.

  According to the rotating body drive control device of the present invention, the gain for feedback control is determined according to the ratio between the standard speed and the target speed, so that it is possible to easily determine the optimal control gain corresponding to a plurality of target speeds. it can. In addition, the control gain does not become excessively large or small, and an oscillation phenomenon or a phenomenon that sufficient control cannot be performed does not occur, and stable control can be performed.

With the configuration of the second aspect, it is possible to perform stable control while preventing the occurrence of an oscillation phenomenon.
According to the configuration of the third aspect, when the target speed is the standard speed, the highly accurate speed control can be performed by the standard gain.

  According to the configuration of claim 4, the circuit configuration for determining the control gain can be realized easily and at a low cost, and at any target speed other than the standard speed, the gain is set lower than the optimum gain in any case. Stable control can be realized without doing so.

With the configuration of the fifth aspect, it is possible to determine control gains corresponding to a plurality of target speeds with a simple configuration using an operational amplifier.
With the configuration of the sixth aspect, it is possible to cope with a plurality of target speeds using a variable resistor.

With the configuration of the seventh aspect, it is possible to cope with a plurality of target speeds using a plurality of resistors having different resistance values.
According to the image forming apparatus of the eighth aspect, the rotating body included in the image forming apparatus can be controlled with high accuracy and stability, so that a high-quality image can be output.

With the configuration of the ninth aspect, the image carrier can be controlled with high accuracy and stability.
With the structure of the tenth aspect, the photosensitive drum can be controlled with high accuracy and stability.

With the structure of the eleventh aspect, the photosensitive belt can be controlled with high accuracy and stability.
According to the configuration of the twelfth aspect, the intermediate transfer drum can be controlled with high accuracy and stability.

With the configuration of the thirteenth aspect, the intermediate transfer belt can be controlled with high accuracy and stability.
According to the structure of the fourteenth aspect, the recording material carrier can be controlled with high accuracy and stability.

With the configuration of the fifteenth aspect, the transfer drum can be controlled with high accuracy and stability.
According to the optical claim of the sixteenth aspect, the transfer / conveying belt can be controlled with high accuracy and stability.

  According to the configuration of the seventeenth aspect, it is possible to realize a color image forming apparatus excellent in image quality and productivity that can output a high-quality color image without color misregistration in a short time.

With the configuration of the eighteenth aspect, it is possible to realize an image forming apparatus including an image reading apparatus that can read a document image with high quality.
According to the configuration of the nineteenth aspect, a moving body on which an optical member is mounted can be driven with high accuracy and a high-quality read image can be obtained under optimum conditions for a plurality of speed conditions in the same manner as standard speeds. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a conventional control system using a speed discriminator will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a conventional example of a control system using a speed discriminator having a plurality of target speeds in addition to a standard speed. In this figure, the reference clock 1 is transmitted by a transmitter or the like according to the speed and is input to the speed discriminator 2. The speed discriminating unit 2 receives a reference clock and, for example, an FG output obtained by measuring the rotational speed of the motor, and outputs a command voltage according to both clocks (details will be described later with reference to FIG. 2). Reference numeral 3 denotes an integration amplifier unit that integrates (smooths) the command voltage output and sets a frequency characteristic such as a gain of the control loop. The output of the integration amplifier unit 3 is input to the PWM oscillation unit 4 for PWM driving. In the PWM oscillation unit 4, a reference signal such as a normal comparator and a triangular wave is used to convert it into a pulsed signal for operating a power semiconductor, for example, a transistor constituting the DC motor driving device 5. The DC motor driving device 5 operates based on the pulse signal and controls the voltage applied to the motor 6. As a result, the motor 6 is driven at a desired speed. Here, the reference clock is set according to a plurality of target speeds.

FIG. 2 is a waveform diagram showing the operation of the speed discriminator 2. FIG. 2A shows the case where the motor speed is slow, and FIG.
In FIG. 2A, when the FG clock is input to the speed discriminating unit 2, counting by the reference clock is started. Since the motor is slower, the reference clock count ends first. During this time, the voltage A, which is normally set to ½ of the voltage between B and C described later, is output. Thereafter, the voltage B is output until the FG clock ends.

  In the case of FIG. 2B in which the motor is faster, the FG clock ends before the reference clock count. The output during that time is the same as the output of A. Thereafter, the voltage C is output until the reference clock is counted. Therefore, the output is A when the FG clock frequency is the same as the reference clock. Since the integration amplifier section described later normally uses inverting amplification, in the case of B output, the output of the integration amplifier becomes smaller and becomes a deceleration command. On the contrary, in the case of C output, the output of the integrating amplifier becomes large and becomes an acceleration command.

  FIG. 3 is a circuit diagram showing a configuration example of the integration amplifier unit. In the illustrated example, an inverting amplifier using an operational amplifier is used. It is clear that the overall gain is proportional to the reciprocal of the input resistance R1 of the operational amplifier.

  Further, as can be seen from FIG. 2, since the speed discriminating uses a clock determined by the motor speed, if expressed using the clock f1, the overall gain is determined by the reciprocal of f1 · R1. Recognize.

  Therefore, when the target speed is halved, the clock f2 becomes f1 / 2, so that the overall control gain is 1 / (f2 · R1) = 2 / (f1 · R1), that is, twice that at f1. I understand that If the standard speed is now f1, the control system is usually designed to be optimal at f1. If f2 is controlled by the integral gain at that time, the gain becomes twice the optimum value, which may cause an oscillation phenomenon. Similarly, when the target speed is doubled, the clock f3 becomes 2 · f1 and the control gain becomes 1 / (f1 · R1 · 2), and the gain becomes 1/2 of the optimum gain. become. This does not change the phase characteristics. FIG. 4 shows a comparison between the standard speed and the case where the target speed is ½ and the case where the target speed is double.

  Next, a control system using the speed discriminator according to the present invention will be described. In addition, the same code | symbol is used for the same or equivalent part as the prior art example of FIG. 1, and the overlapping description is abbreviate | omitted.

  In FIG. 5, reference numeral 13 denotes a calculation unit for calculating a speed ratio, which calculates a standard speed / target speed from a standard speed and a target speed, and a value obtained by multiplying the integral amplifier input resistance R1 at the standard speed by that value. Select. The integrating amplifier unit 14 changes the input resistance R1 according to the value. Specifically, this can be realized by using a variable resistor R61 as shown in FIG. 6, or by selecting a resistor row arranged by the number of target speeds with a selector as shown in FIG. The standard speed is one of the target speeds. When the standard speed is controlled (target speed = standard speed), the ratio between them, that is, standard speed / target speed = 1.

  In addition, here, the control using only the speed discriminator method is described as an example, but the same applies to a control system using both speed discriminator (control by the speed discriminator method) and pulse phase control (PLL control). Can be implemented.

  By the way, in actual cases, arranging the operational amplifier inputs for all the target speeds increases the cost and also increases the installation area. Therefore, it can be considered that the placement resistance is less than the number of target speeds.

  For example, as shown in FIG. 8, a configuration in which two resistors are arranged is possible regardless of the target speed. In this case, a resistor R81 for determining an optimum gain at a standard speed and a resistor R82 having a value obtained by multiplying the resistor 81 by the standard speed / target speed when the target speed is the slowest are prepared. When the target speed is controlled to a speed other than the standard speed, the resistor 81 is used when the target speed is faster than the standard speed, and the resistor R82 is selected and used when the target speed is slower than the standard speed. Thus, in any case (except for the standard speed), the gain is set lower than the optimum gain for each target speed, so that stable control can be performed without oscillation. In addition, when controlling to a standard speed, resistance R81 is used. Here, the case where there are two control gains has been described, but it is also possible to set the gain to an arbitrary number such as three (three steps).

  The control system in this case has a configuration example as shown in FIG. In FIG. 9, the output of the speed ratio calculation unit 13 is input to the gain selection unit 15, and the input resistance is selected by the integration amplifier unit 14 based on the output from the gain selection unit 15.

  FIG. 10 is a perspective view showing an embodiment of a rotating body drive control device to which a control system using the speed discriminator according to the present invention is applied. The illustrated example is an example of a drive control device that controls a drum-like rotating body as a rotating body of the image forming apparatus. Examples of the drum-shaped rotating body in this example include a photosensitive drum or an intermediate transfer drum that is an image carrier, and a transfer drum that rotates by carrying (holding) a recording material.

  In FIG. 10, reference numeral 501 denotes a motor as a drive source for rotationally driving the rotating body. Is transmitted to. A DC motor is used for the motor 501, and the photosensitive drum or transfer drum 505 is firmly fixed to the shaft 506. The motor 501 is provided with an FG output and outputs a pulse according to the rotation of the motor. In addition to the motor FG, the encoder may be, for example, an encoder attached to the drum shaft 505, or a method of reading lines at regular intervals written on the surface of the drum 505.

  FIG. 11 is a perspective view showing another embodiment of the rotating body drive control device to which the control system using the speed discriminator according to the present invention is applied. The illustrated example is an example of a drive control device that controls an endless belt-like rotating body as a rotating body of the image forming apparatus. Examples of the endless belt-like rotating body in this example include a photosensitive belt or an intermediate transfer belt, which is an image carrier, and a conveyance belt or a transfer conveyance belt that carries (holds) and conveys a recording material.

  The rotating body drive control device shown in FIG. 11 includes a DC motor 31 as drive means for rotationally driving the endless belt 20, and the rotational torque of the motor 31 is a deceleration system that constitutes a power transmission system, for example, a timing belt. 33 is transmitted to the drive shaft 35 and the drive roller 34 of the endless belt 20. Since the endless belt 20 is wound around the driving roller 34 and the driven rollers 21, 22, 23, 24, 25, when the driving roller 34 is rotated by the pulse motor 31, the endless belt 20 is rotated accordingly. The endless belt 20 moves. Here, the driven roller 24 is a tension roller, and is strongly pressed against the belt by a tension member such as a spring, and has a mechanism for absorbing the movement of the belt with this tension. The encoder 36 is a state detection device that detects the angular displacement of the driven roller 24 and is attached to the driven roller 24 via a coupling. In addition to the driven shaft, the encoder may be, for example, an encoder attached to a motor shaft, or a system that reads lines at regular intervals written on the surface of the belt 20.

  10 and 11, when the motors 1501 and 31 for rotating the rotating body, that is, the drum 1505 or the endless belt 20, are driven and controlled by the control system shown in FIG. The standard speed for copying and printing is fixed. The driving speed is set in advance according to conditions such as the type and magnification of the output paper, color, and monochrome mode. Therefore, necessary operational amplifier input resistance (input resistance of the integrating amplifier unit 14) can be prepared in advance. In these modes, since the user inputs the setting conditions before the output start switch is pressed, the input resistance can be selected at that time (that is, in advance).

  In the rotating body drive control device according to the present invention, the optimum control gain corresponding to a plurality of target speeds other than the standard speed can be easily determined, so that the rotating body can be stably controlled with high accuracy. it can. Further, when the rotating body drive control device according to the present invention is used for controlling the rotating body of the image forming apparatus or the image reading apparatus, the photosensitive drum or A rotating body such as a photosensitive belt or a transfer belt can be stably controlled with high accuracy, and high-quality image output or input is possible.

  Next, an embodiment in which the present invention is applied to an electrophotographic direct color transfer color laser printer (hereinafter referred to as “laser printer”) as an image forming apparatus will be described with reference to FIGS.

  FIG. 12 is a cross-sectional view showing a schematic configuration of a laser printer as an example of an image forming apparatus to which the present invention is applied. The laser printer shown in this figure has four sets of image forming units 41Y, 41M, 41C, 41K (for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). Hereinafter, the subscripts Y, M, C, and K of the respective symbols indicate yellow, magenta, cyan, and black members, respectively, and the moving direction of the transfer paper P (the belt along the arrow A in the figure). 60 in the traveling direction) are arranged in order from the upstream side. Each of the image forming units 41Y, 41M, 41C, and 41K is provided with photosensitive drums 51Y, 51M, 51C, and 51K as image carriers, and charging around the photosensitive drums 51 is necessary for the electrophotographic process. And a developing unit are arranged. The arrangement of the image forming units 41Y, 41M, 41C, and 41K is set so that the rotation axes of the photosensitive drums are parallel to each other and arranged at a predetermined pitch in the transfer sheet moving direction.

  In addition to the image forming units 41Y, 41M, 41C, and 41K, the laser printer carries an optical writing unit 72, paper feed cassettes 73 and 74, a pair of registration rollers 75, and transfer paper P, and transfers each image forming unit. A transfer unit 76 as a belt driving device having a transfer conveyance belt 60 as a transfer conveyance member that conveys the sheet so as to pass through a position, a belt fixing type fixing unit 77, a paper discharge tray 78, and the like are provided. In addition, a manual feed tray MF and a toner supply container TC are provided, and a waste toner bottle, a duplex / reversing unit, a power supply unit, and the like (not shown) are also provided in a space S indicated by a two-dot chain line.

  The optical writing unit 72 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each of the photosensitive drums 51Y, 51M, 51C, and 51K while scanning the laser beam based on the image data. To do.

FIG. 13 is an enlarged view showing a schematic configuration of the transfer unit 76. The transfer conveyance belt 60 used in the transfer unit 76 is a high-resistance endless single-layer belt having a volume resistivity of 10 ⁹ to 10 ¹¹ Ωcm, and the material thereof is PVDF (polyvinylidene fluoride). The transfer / conveying belt 60 is wound around support rollers 61 to 68 so as to pass through the transfer positions that are in contact with and face the photosensitive drums 51Y, 51M, 51C, and 51K of the toner image forming units.

  Among these support rollers, the entrance roller 61 on the upstream side in the transfer sheet moving direction is disposed on the outer peripheral surface of the transfer conveyance belt 60 so that the electrostatic adsorption roller 80 to which a predetermined voltage is applied from the power source 65a is opposed. Yes. The transfer paper P that has passed between the two rollers 61 and 80 is electrostatically attracted onto the transfer conveyance belt 60.

A roller 63 is a drive roller that frictionally drives the transfer conveyance belt 60, and is connected to a drive source (not shown) and rotates in the direction of the arrow.
Transfer bias applying members 67Y, 67M, 67C, and 67K are provided as transfer electric field forming means for forming a transfer electric field at each transfer position so as to be in contact with the back surface of the transfer conveyance belt 60 at a position facing the photosensitive drum. ing. These are bias rollers provided with a sponge or the like on the outer periphery, and a transfer bias is applied to the roller mandrel from each transfer bias power source 79Y, 79M, 79C, 79K. Due to the action of the applied transfer bias, a transfer charge is applied to the transfer conveyance belt 60, and a transfer electric field having a predetermined strength is formed between the transfer conveyance belt 60 and the surface of the photosensitive drum at each transfer position. In addition, a backup roller 68 is provided to keep the contact between the transfer paper and the photoconductor in the area where the transfer is performed, and to obtain the best transfer nip.

  The transfer bias applying members 67Y, 67M, and 67C and the backup roller 68 disposed in the vicinity thereof are integrally held by a swing bracket 93 so as to be rotatable, and can be rotated around a rotation shaft 94. This rotation is clockwise when the cam 96 fixed to the cam shaft 97 is rotated in the direction of the arrow.

  The entrance roller 61 and the suction roller 80 are integrally supported by the entrance roller bracket 90, and can be rotated clockwise from the state shown in FIG. A hole 95 provided in the swing bracket 93 and a pin 92 fixed to the entrance roller bracket 90 are engaged with each other, and rotate in conjunction with the rotation of the swing bracket 93. By the clockwise rotation of these brackets 90, 93, the bias applying members 67Y, 67M, 67C and the backup roller 68 disposed in the vicinity thereof are separated from the photoreceptors 51Y, 51M, 51C, and the entrance roller 61 and the suction roller 80 also moves downward. It is possible to avoid contact between the photoconductors 51Y, 51M, and 51C and the transfer conveyance belt 60 when forming a black-only image.

  On the other hand, the transfer bias applying member 67K and the backup roller 68 adjacent to the transfer bias applying member 67K are rotatably supported by the outlet bracket 98, and are rotatable about a shaft 99 coaxial with the outlet roller 62. When the transfer unit 6 is attached to or detached from the main body, it is rotated clockwise by operating a handle (not shown), and the transfer bias applying member 67K and the adjacent backup roller 68 are moved from the black image forming photosensitive member 51K. They are separated.

  A cleaning device 85 composed of a brush roller and a cleaning blade is disposed on the outer peripheral surface of the transfer conveyance belt 60 wound around the driving roller 63. The cleaning device 85 removes foreign matters such as toner adhering to the transfer conveyance belt 60.

  A roller 64 is provided downstream of the driving roller 63 in the traveling direction of the transfer conveyance belt 60 in a direction to push the outer peripheral surface of the transfer conveyance belt, and a winding angle around the drive roller 83 is ensured. A tension roller 65 that applies tension to the belt with a pressing member (spring) 69 is provided in the loop of the transfer conveyance belt 60 further downstream from the roller 64. An encoder for control (not shown) is attached to the tension roller via a coupling.

  The alternate long and short dash line in FIG. 12 indicates the conveyance path of the transfer paper P. The transfer paper P fed from the paper feed cassettes 73 and 74 or the manual feed tray MF is transported by a transport roller while being guided by a transport guide (not shown), and is transported to a temporary stop position where a registration roller pair 75 is provided. The transfer paper P delivered by the registration roller pair 75 at a predetermined timing is carried on the transfer conveyance belt 60, conveyed toward the image forming units 41Y, 41M, 41C, and 41K, and passes through the transfer nips.

  The toner images developed on the photosensitive drums 51Y, 51M, 51C, and 51K of the image forming units 41Y, 41M, 41C, and 41K are superimposed on the transfer paper P at the respective transfer nips, and the transfer electric field and the nip pressure described above. Is transferred onto the transfer paper P. A full color toner image is formed on the transfer paper P by this superposition transfer.

  The surfaces of the photosensitive drums 51Y, 51M, 51C, and 51K after the toner image transfer are cleaned by a cleaning device, and are further neutralized to prepare for the formation of the next electrostatic latent image.

  On the other hand, the transfer paper P on which the full-color toner image is formed is fixed in the first discharge direction B or the second in accordance with the rotation posture of the switching guide G after the full-color toner image is fixed by the fixing unit 77. In the paper discharge direction C. When the paper is discharged from the first paper discharge direction B onto the paper discharge tray 78, it is stacked in a so-called face-down state with the image surface down. On the other hand, when the paper is discharged in the second paper discharge direction C, it is conveyed toward another post-processing device (not shown) (sorter, binding device, etc.), or registered again for double-sided printing via a switchback unit. It is conveyed to the roller pair 75.

  In such an image forming apparatus, the drive control of the paper transport belt 60 is performed with respect to the drive roller 63 of the paper transport belt by one of the driven rollers or an encoder attached to the motor.

  As described above, by using the present invention for the transfer material conveyance belt drive system, the drive system can be highly accurate under optimum conditions as well as the standard speed for a plurality of speed conditions set according to the paper type and the like. The drive can be controlled to obtain a high quality image.

Next, one embodiment in which the present invention is applied to an intermediate transfer type color copying machine will be described with reference to FIG.
FIG. 14 is a cross-sectional view showing a schematic configuration of a color copying machine as an example of an image forming apparatus to which the present invention is applied. In this figure, a drum-shaped photosensitive member (photosensitive drum) 210 as an image carrier is provided slightly to the right of the center in the apparatus main body 201 of the copying machine. Around the photosensitive member 210, a developing device 212, an intermediate transfer unit 213, and a cleaning device 214 as developing means are sequentially arranged in the rotational direction (counterclockwise) indicated by an arrow from a charger 211 installed thereon. , Static eliminator 215 and the like are arranged.

  On these charger 211, rotary developing device 212, cleaning device 214, and static eliminator 215, an optical writing device as an exposure unit, for example, a laser writing device 218 is installed. The rotary developing device 212 includes developing units 231Y, 231M, 231C, and 231K that store toners of yellow, magenta, cyan, and black, respectively, and rotates around the central axis to develop the developing units 231Y, 231M, 231C and 231K are selectively moved to a development position facing the outer periphery of the photoreceptor 210.

  In the intermediate transfer unit 213, an endless intermediate transfer body (in this example, an intermediate transfer belt) 219 serving as an image carrier is wound around a plurality of driven roller rollers and drive rollers, and the intermediate transfer belt 219 is placed on the photoreceptor 210. Abutted. A primary transfer device 220 is installed inside the intermediate transfer belt 219, and a secondary transfer device 221 and a cleaning device 222 are installed outside the intermediate transfer belt 219. The cleaning device 222 is provided so as to be able to contact with and separate from the intermediate transfer belt 219.

  Here, reference numeral 223 denotes a tension roller that applies tension to the intermediate transfer belt 219, and an encoder (not shown) for control is attached thereto. The position of the encoder may be any other driven roller shaft, motor shaft, drum surface, or belt surface as before.

  A recording medium conveyance path 224 positioned below the intermediate transfer unit 213 conveys a recording medium such as a sheet from right to left. In the recording medium conveyance path 224, a registration roller 225 is installed in front of the intermediate transfer unit 213 and the secondary transfer device 221, and a conveyance belt 226, a fixing device 227, a downstream of the intermediate transfer unit 213 and the secondary transfer device 221, A paper discharge roller 228 is disposed.

  The laser writing device 218 receives an image signal of each color from the image reading device 200 via an image processing unit (not shown), and applies the laser light L sequentially modulated by the image signal of each color to the photoconductor 210 in a uniformly charged state. Irradiation exposes the photoreceptor 210 to form an electrostatic latent image on the photoreceptor 210. The image reading apparatus 200 color-separates and reads an image of a document G set on a document table provided on the upper surface of the main body, and converts it into an electrical image signal.

  A sheet feeding device 230 is disposed below the copying machine main body 201. A plurality of paper feed cassettes 231a to 231c are provided in multiple stages in the paper feed device 230, and any one of the paper feed rollers 232a to 232c is selectively driven to record from any one of the paper feed cassettes 231. Media is sent out. The recording medium is conveyed to the recording medium conveyance path 224 through the automatic paper feeding path 229 in the copying machine main body 201. A manual feed tray 216 is provided on the right side of the copying machine main body 201 so as to be openable and closable. A recording medium inserted from the manual feed tray 216 is conveyed to a recording medium conveyance path 224. A paper discharge tray (not shown) is detachably attached to the left side of the copying machine main body 201, and the recording medium discharged by the paper discharge roller 228 is stored in the paper discharge tray.

  In the color copying machine configured as described above, when making a color copy, when a document G is set on a document table and a start switch (not shown) is pressed, a copying operation is started. First, the image reading apparatus 200 separates and reads an image of the document G on the document table. At the same time, the recording medium is selectively sent out from the paper feeding cassette 231 in the paper feeding device 230 by the paper feeding roller 232, and the recording medium hits the registration roller 225 through the automatic paper feeding path 229 and stops.

  The photoreceptor 210 rotates counterclockwise, and the intermediate transfer belt 219 rotates clockwise. The photoconductor 210 is uniformly charged by the charger 211 as it rotates, and laser light modulated by the image signal of the first color applied to the laser writing device 218 from the image reading device 200 via the image processing unit is laser-written. Irradiation from the device 218 forms an electrostatic latent image.

  The electrostatic latent image on the photosensitive member 210 is developed by the first color developing device 231Y of the rotary developing device 212 to become a first color image. The first color image on the photosensitive member 210 is intermediated by the primary transfer device 220. The image is transferred to the transfer belt 219. The photosensitive member 210 is cleaned by the cleaning device 214 after the transfer of the first color image to remove the residual toner, and is discharged by the charge eliminator 215.

  Subsequently, the photosensitive member 210 is uniformly charged by the charger 211, and the laser beam modulated by the image signal of the second color applied from the image reading device 200 to the laser writing device 218 via the image processing unit is applied to the laser writing device. Irradiation from 218 forms an electrostatic latent image. The electrostatic latent image on the photoconductor 210 is developed by the second color developing device 231M of the rotary developing device 212 to become a second color image, and the second color image on the photoconductor 210 is intermediated by the primary transfer device 220. The image is transferred onto the transfer belt 219 so as to overlap the first color image. The photoreceptor 210 is cleaned by the cleaning device 214 after the transfer of the image of the second color to remove the residual toner, and is neutralized by the static eliminator 215.

  The photosensitive member 210 is uniformly charged by the charger 211, and the laser beam modulated by the image signal of the third color applied from the image reading device 200 to the laser writing device 218 via the image processing unit is the laser writing device 218. To form an electrostatic latent image. The electrostatic latent image on the photoconductor 210 is developed by the third color developing device 231C of the rotary developing device 212 to become an image of the third color, and the image of the third color on the photoconductor 210 is intermediated by the primary transfer device 220. The first color image and the second color image are superimposed on the transfer belt 219 and transferred. The photosensitive member 210 is cleaned by the cleaning device 214 after the transfer of the image of the third color to remove the residual toner, and is discharged by the charge eliminator 215.

  Further, the photosensitive member 210 is uniformly charged by the charger 211, and the laser beam modulated by the image signal of the fourth color applied from the image reading device 200 to the laser writing device 218 via the image processing unit is the laser writing device 218. To form an electrostatic latent image. The electrostatic latent image on the photosensitive member 210 is developed by the fourth color developing device 231K of the rotary developing device 212 to become a fourth color image. The fourth color image on the photosensitive member 210 is intermediated by the primary transfer device 220. A full-color image is formed on the transfer belt 219 by superimposing and transferring the first-color image, the second-color image, and the third-color image. The photosensitive member 210 is cleaned by the cleaning device 214 after the transfer of the image of the fourth color to remove residual toner, and is discharged by the charge eliminator 215. Note that the order of the image forming colors is not limited to the exemplified Y, M, C, and K.

  Then, the registration roller 225 rotates at a timing to feed the recording medium, and the full color image on the intermediate transfer belt 219 is transferred to the recording medium by the action of the secondary transfer device 221. This recording medium is transported by a transport belt 226, a full color image is fixed by a fixing device 227, and is discharged to a paper discharge tray by a paper discharge roller 228. Further, the intermediate transfer belt 219 is cleaned by the cleaning device 222 after the transfer of the full color image, and the residual toner is removed.

  The operation for forming a four-color superimposed image has been described above. When a three-color superimposed image is formed, three different single-color images are sequentially formed on the photosensitive member 210 and transferred onto the intermediate transfer belt 219. In the case where a two-color superimposed image is formed by batch transfer to a recording medium, two different single-color images are sequentially formed on the photosensitive member 210 and transferred onto the intermediate transfer belt 219 in an overlapping manner. It is transferred to a recording medium at once. When a single color image is formed, one single color image is formed on the photoreceptor 210 and transferred onto the intermediate transfer belt 219 and then transferred to a recording medium.

  In such a color copying machine, the rotational accuracy of the intermediate transfer member serving as the image carrier greatly affects the quality of the final image, and higher-precision drive control of the image carrier (intermediate transfer member) is desired. Therefore, in the present embodiment, drive control of the intermediate transfer belt 219 is performed by the control system of the present invention.

  In this embodiment, by using the present invention for driving control of the image carrier 219, the same driving is performed under optimum conditions as well as a standard speed for a plurality of speed conditions set according to the paper type and the like. The system can be driven with high accuracy, and high quality images can be obtained.

Next, an embodiment in which the present invention is applied to an intermediate transfer type image forming apparatus using a belt-like photoreceptor (image carrier) will be described with reference to FIG.
FIG. 15 is a cross-sectional view showing the main configuration of a color copying machine as an example of an image forming apparatus to which the present invention is applied. In this figure, a photoreceptor 101 as an image carrier is a photoreceptor in which a photosensitive layer such as an organic optical semiconductor (OPC) is formed in a thin film on the outer peripheral surface of a closed loop Ni (nickel) belt base material. It is a belt. The photosensitive member 101 is supported by three photosensitive member conveying rollers 102 to 104 and is rotated in the direction of arrow A by a drive motor (not shown).

  The driven roller 103 is a tension roller, and 102 is a drive roller. The encoder used for control is attached to the tension roller 103. Note that the position of the encoder may be any other driven roller shaft, motor shaft, drum surface, or belt surface as before.

  Around the photoconductor 101, in order of the photoconductor rotation direction indicated by an arrow A, a charger 105, an exposure optical system (hereinafter referred to as LSU) 106 as an exposure unit, and a developer 107 of black, yellow, magenta, and cyan colors. ˜110, an intermediate transfer unit 111, a photoconductor cleaning means 112, and a static eliminator 113 are provided. The charger 105 is applied with a high voltage of about −4 to 5 kV from a power supply device (not shown), and charges the portion of the photoconductor 101 facing the charger 105 to give a uniform charging potential.

  The LSU 106 sequentially modulates light intensity or pulse width of each color image signal from a gradation converting means (not shown) by a laser drive circuit (not shown), and a semiconductor laser (not shown) using the modulated signal. , The exposure light beam 114 is obtained, and the photosensitive member 101 is scanned with the exposure light beam 114 to sequentially form electrostatic latent images corresponding to the image signals of the respective colors on the photosensitive member 101. The seam sensor 115 detects the joint of the photoconductor 101 formed in a loop shape. When the seam sensor 115 detects the seam of the photoconductor 101, it avoids the seam of the photoconductor 101 and each color is detected. The timing controller 116 controls the light emission timing of the LSU 106 so that the electrostatic latent image forming positions are the same.

  Each of the developing devices 107 to 110 stores toner corresponding to each developing color, and is selectively applied to the photosensitive member 101 at a timing corresponding to the electrostatic latent image corresponding to the image signal of each color on the photosensitive member 101. The electrostatic latent image on the photosensitive member 101 is abutted and developed with toner to form an image of each color, thereby forming a full-color image by a four-color superimposed image.

  The intermediate transfer unit 111 includes a drum 117 as an intermediate transfer member in which a belt-like sheet made of conductive resin or the like is wound around a metal base tube such as aluminum, and an intermediate transfer member cleaning unit in which rubber or the like is formed in a blade shape. The intermediate transfer member cleaning unit 118 is separated from the intermediate transfer member 117 while the four-color superimposed image is formed on the intermediate transfer member 117. The intermediate transfer member cleaning unit 118 contacts the intermediate transfer member 117 only when the intermediate transfer member 117 is cleaned, and removes toner remaining without being transferred from the intermediate transfer member 117 to the recording paper 119 as a recording medium. The recording sheets are sent one by one from the recording sheet cassette 120 to the sheet conveying path 122 by the sheet feeding roller 121.

  The transfer unit 123 serving as a transfer unit transfers the full color image on the intermediate transfer body 117 to the recording paper 119. The transfer unit 124 in which conductive rubber or the like is formed in a belt shape, and the transfer unit 123 on the intermediate transfer body 117. A transfer device 125 that applies a transfer bias for transferring a full color image to the recording paper 119 to the intermediate transfer body 117, and the recording paper 119 is electrostatically applied to the intermediate transfer body 117 after the full color image is transferred to the recording paper 119. The separator 126 is configured to apply a bias to the intermediate transfer member 117 so as to prevent sticking.

  The fixing device 127 includes a heat roller 128 having a heat source therein and a pressure roller 129. The full-color image transferred onto the recording paper 119 is rotated between recording rollers of the heat roller 128 and the pressure roller 129. Accordingly, pressure and heat are applied to the recording paper 119 to fix the full-color image on the recording paper 119 to form a full-color image. The operation of the sixth embodiment configured as described above will be described below. Here, the description will proceed assuming that the development of the electrostatic latent image is performed in the order of black, cyan, magenta, and yellow.

  The photosensitive member 101 and the intermediate transfer member 117 are driven in the directions of arrows A and B by respective driving sources (not shown). In this state, first, a high voltage of about −4 to 5 kV is applied to the charger 105 from a power supply device (not shown), and the charger 105 uniformly charges the surface of the photoreceptor 101 to about −700V. Next, after the seam sensor 115 detects the seam of the photoconductor 101 and after a predetermined time has passed so as to avoid the seam of the photoconductor 101, the laser beam corresponding to the black image signal from the LSU 106 is applied to the photoconductor 101. The exposure light beam 114 is irradiated, and the photosensitive member 101 loses the charge of the portion irradiated with the exposure light beam 114 to form an electrostatic latent image.

  On the other hand, the black developing device 107 is brought into contact with the photosensitive member 101 at a predetermined timing. The black toner in the black developing device 107 is given a negative charge in advance, and the black toner adheres only to a portion (electrostatic latent image portion) where the charge has disappeared due to the irradiation of the exposure light beam 114 on the photoreceptor 101. Development is performed by a so-called negative-positive process. The black toner image formed on the surface of the photosensitive member 101 by the black developing unit 107 is transferred to the intermediate transfer member 117. Residual toner that has not been transferred from the photoconductor 101 to the intermediate transfer body 117 is removed by the photoconductor cleaning means 112, and the charge on the photoconductor 101 is removed by the static eliminator 113.

  Next, the charger 105 uniformly charges the surface of the photoreceptor 101 to about −700V. Then, after the seam sensor 115 detects the seam of the photoconductor 101, a predetermined time elapses so as to avoid the seam of the photoconductor 101, and exposure of the laser beam corresponding to the cyan image signal from the LSU 106 is performed on the photoconductor 101. The photosensitive member 101 is irradiated with the light beam 114 and the charge of the portion irradiated with the exposure light beam 114 disappears to form an electrostatic latent image.

  On the other hand, the cyan developing unit 108 is brought into contact with the photosensitive member 101 at a predetermined timing. The cyan toner in the cyan developing unit 108 is given a negative charge in advance, and the cyan toner adheres only to the portion (electrostatic latent image portion) where the charge disappears due to the irradiation of the exposure light beam 114 on the photosensitive member 101, Development is performed by a so-called negative-positive process. The cyan toner image formed on the surface of the photosensitive member 101 by the cyan developing unit 108 is transferred onto the intermediate transfer member 117 so as to overlap the black toner image. Residual toner that has not been transferred from the photoconductor 101 to the intermediate transfer body 117 is removed by the photoconductor cleaning means 112, and the charge on the photoconductor 101 is removed by the static eliminator 113.

  Next, the charger 105 uniformly charges the surface of the photoreceptor 101 to about −700V. Then, after the seam sensor 115 detects the seam of the photoconductor 101 and after a certain time has passed so as to avoid the seam of the photoconductor 101, exposure of the laser beam corresponding to the magenta image signal from the LSU 106 to the photoconductor 101 is performed. The photosensitive member 101 is irradiated with the light beam 114 and the charge of the portion irradiated with the exposure light beam 114 disappears to form an electrostatic latent image.

  On the other hand, a magenta developing device 109 is brought into contact with the photosensitive member 101 at a predetermined timing. The magenta toner in the magenta developing device 109 is previously given a negative charge, and the magenta toner adheres only to the portion (electrostatic latent image portion) where the charge has disappeared due to the irradiation of the exposure light beam 114 on the photoreceptor 101. Development is performed by a so-called negative-positive process. The magenta toner image formed on the surface of the photosensitive member 101 by the magenta developing unit 109 is transferred onto the intermediate transfer member 117 so as to overlap the black toner image and the cyan toner image. Residual toner that has not been transferred from the photoconductor 101 to the intermediate transfer body 117 is removed by the photoconductor cleaning means 112, and the charge on the photoconductor 101 is removed by the static eliminator 113.

  Further, the charger 105 uniformly charges the surface of the photoreceptor 101 to about −700V. Then, after the seam sensor 115 detects the joint of the photoconductor 101, a predetermined time elapses so as to avoid the joint of the photoconductor 101, and the photoconductor 101 is exposed to the laser beam corresponding to the yellow image signal from the LSU 106. The photosensitive member 101 is irradiated with the light beam 114 and the charge of the portion irradiated with the exposure light beam 114 disappears to form an electrostatic latent image.

  On the other hand, the yellow developing device 110 contacts the photoconductor 101 at a predetermined timing. The yellow toner in the yellow developing device 110 is given a negative charge in advance, and the yellow toner adheres only to the portion (electrostatic latent image portion) where the charge has disappeared due to the irradiation of the exposure light beam 114 on the photoreceptor 101. Development is performed by a so-called negative-positive process. The yellow toner image formed on the surface of the photosensitive member 101 by the yellow developing device 110 is transferred onto the intermediate transfer member 117 so as to overlap the black toner image, the cyan toner image, and the magenta toner image, and a full-color image is formed on the intermediate transfer member 117. It is formed. Residual toner that has not been transferred from the photoconductor 101 to the intermediate transfer body 117 is removed by the photoconductor cleaning means 112, and the charge on the photoconductor 101 is removed by the static eliminator 113.

  In the full-color image formed on the intermediate transfer body 117, the transfer unit 123 that has been separated from the intermediate transfer body 117 so far contacts the intermediate transfer body 117, and a high voltage of about +1 kV is applied to the transfer device 125 by a power supply device (see FIG. (Not shown), the transfer device 125 collectively transfers the recording paper 119 transported along the paper transport path 122 from the recording paper cassette 120.

  In addition, a voltage is applied from the power supply device to the separator 126 so that an electrostatic force attracting the recording paper 119 acts, and the recording paper 119 is peeled off from the intermediate transfer body 117. Subsequently, the recording paper 119 is sent to the fixing device 127, where the full color image is fixed by the nipping pressure between the heat roller 128 and the pressure roller 129 and the heat of the heat roller 128, and the paper discharge tray 130 discharges the paper. It is discharged to 131.

  Further, residual toner on the intermediate transfer member 117 that has not been transferred onto the recording paper 119 by the transfer unit 123 is removed by the intermediate transfer member cleaning means 118. The intermediate transfer member cleaning unit 118 is located away from the intermediate transfer member 117 until a full color image is obtained. After the full color image is transferred to the recording paper 119, the intermediate transfer member 117 comes into contact with the intermediate transfer member 117 and is on the intermediate transfer member 117. Remove residual toner. The full color image formation for one sheet is completed by the series of operations described above.

  In such a color image forming apparatus, the rotational accuracy of the photosensitive belt 101 as an image carrier greatly affects the quality of the final image, and higher-precision drive control of the image carrier 101 is desired.

  In this embodiment, by using the present invention for driving control of the photosensitive belt 101, the same driving is performed under optimum conditions as well as the standard speed for a plurality of speed conditions set according to the paper type and the like. The system can be driven with high accuracy, and high quality images can be obtained.

Next, one embodiment in which the present invention is applied to a tandem type intermediate transfer type color image forming apparatus will be described with reference to FIG.
FIG. 16 is a cross-sectional view showing a schematic configuration of a color copying machine which is an example of an image forming apparatus to which the present invention is applied. In this figure, reference numeral 310 is a copying machine main body, 320 is a paper feed table on which it is placed, 330 is a scanner mounted on the copying apparatus main body 310, and 340 is an automatic document feeder (ADF) further mounted thereon.

  The copying machine main body 310 is provided with an endless belt-shaped intermediate transfer member 301 at the center. In the intermediate transfer member 301, a base layer is made of a base layer made of a material that hardly stretches, such as a canvas made of a fluororesin having a small elongation or a rubber material having a large elongation, and an elastic layer is provided thereon. The elastic layer is made of, for example, fluorine rubber or acrylonitrile-butadiene copolymer rubber. The surface of the elastic layer is covered with a coat layer 13 having good smoothness by coating, for example, a fluorine-based resin.

  As shown in FIG. 16, in the illustrated example, the belt-shaped intermediate transfer member 301 is wound around four support rollers 302 to 305 so as to be able to rotate and convey clockwise in the drawing. Of these, the tension roller 305 is provided with an encoder (not shown) for use in drive control. Note that the position of the encoder may be any other driven roller shaft, motor shaft, drum surface, or belt surface as before.

  In this illustrated example, an intermediate transfer member cleaning device 306 is provided on the left side of the second support roller 303 to remove residual toner remaining on the intermediate transfer member 301 after image transfer.

  In addition, four image forming units 311 of yellow, cyan, magenta, and black are horizontally disposed along the conveyance direction on the upper side of the intermediate transfer member 301 between the first support roller 302 and the second support roller 303. The tandem image forming unit 350 is arranged side by side. Each image forming unit 311 includes a photosensitive drum 312, and around the photosensitive drum 312, a charger, a developing device, a transfer roller as a primary transfer unit, a cleaning device, and a static eliminator necessary for an electrophotographic process. Etc. are arranged. An exposure device 307 is disposed on the tandem image forming unit 350.

  On the other hand, a secondary transfer device 315 is provided on the opposite side of the intermediate transfer member 301 from the tandem image forming unit 350. In the illustrated example, the secondary transfer device 315 includes a secondary transfer belt 316 that is an endless belt between two rollers, and is pressed against the third support roller 304 via the intermediate transfer member 301. The image on the intermediate transfer member 301 is transferred to a sheet.

  Next to the secondary transfer device 315, a fixing device 317 for fixing the transferred image on the sheet is provided. The fixing device 317 of this example is configured by pressing a pressure roller against a fixing belt which is an endless belt.

  The secondary transfer device 315 described above also has a sheet conveyance function for conveying the sheet after image transfer to the fixing device 317. Of course, a transfer roller or a non-contact charger may be disposed as the secondary transfer device 315. In such a case, it is difficult to provide this sheet conveyance function together. In the illustrated example, a sheet reversing device 308 for reversing the sheet to record images on both sides of the sheet is provided below the secondary transfer device 315 and the fixing device 317.

  Now, when making a copy using this color copying machine, the document is set on the document table 341 of the automatic document feeder 340. Alternatively, the automatic document feeder 340 is opened, a document is set on the contact glass 331 of the scanner 330, and the automatic document feeder 340 is closed and pressed by it.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 340, the document is transported and moved onto the contact glass 331, and then the document is set on the other contact glass 331. At that time, the scanner 33 is immediately driven to travel on the first traveling body 332 and the second traveling body 333. Then, the first traveling body 332 emits light from the light source, and the reflected light from the document surface is further reflected toward the second traveling body 333, reflected by the mirror of the second traveling body 333, and passed through the imaging lens 334. The document is placed in the reading sensor 335 and the original content is read.

  When a start switch (not shown) is pressed, the other three support rollers are driven to rotate by a drive motor and a drive roller (not shown), and the intermediate transfer member 301 is rotated and conveyed. At the same time, the image forming units 311 rotate the photoconductors 312 to form black, yellow, magenta, and cyan monochrome images on the photoconductors 312, respectively. Then, along with the conveyance of the intermediate transfer member 301, these single color images are sequentially transferred to form a composite color image on the intermediate transfer member 301.

  On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 321 of the paper feed table 320 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 323 provided in multiple stages in the paper bank 322, thereby separating rollers 324. Are separated one by one into the paper feed path 325, transported by the transport roller 326, guided to the paper feed path 327 in the copier body 310, and abutted against the registration roller 328 and stopped.

  Alternatively, the sheet feed roller 329 is rotated to feed out the sheets on the manual feed tray 336, separated one by one by the separation roller 337, put into the manual feed path 338, and abutted against the registration roller 328 and stopped.

  Then, the registration roller 328 is rotated in synchronization with the composite color image on the intermediate transfer member 301, the sheet is fed between the intermediate transfer member 301 and the secondary transfer device 215, and transferred by the secondary transfer device 215. A color image is recorded on the sheet. In general, the registration roller 328 is often used while being grounded, but it is also possible to apply a bias for removing paper dust from the sheet.

  The sheet after the image transfer is conveyed by the secondary transfer device 215 and sent to the fixing device 317. The fixing device 317 applies heat and pressure to fix the transferred image, and then the image is switched by the switching claw 339 and discharged. The paper is discharged at 342 and stacked on the paper discharge tray 343. Alternatively, it is switched by the switching claw 339 and put into the sheet reversing device 308, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 343 by the discharge roller 342.

  On the other hand, the intermediate transfer body 301 after the image transfer is removed by the intermediate transfer body cleaning device 306 to remove the residual toner remaining on the intermediate transfer body 301 after the image transfer, so that the tandem image forming unit 350 can prepare for another image formation.

  In such a color copying machine, the driving accuracy of the intermediate transfer belt 301 has a great influence on the quality of the final image, and higher accuracy driving is desired. Therefore, the above-described drive control device of the present invention is used as an intermediate transfer belt drive system of such a color copying machine.

  In this embodiment, by using the present invention for driving control of the intermediate transfer belt 301, the same driving is performed under optimum conditions as well as the standard speed for a plurality of speed conditions set according to the paper type and the like. The system can be driven with high accuracy, and high quality images can be obtained.

Next, an embodiment in which the present invention is applied to an image reading apparatus (running body driving apparatus) will be described with reference to FIG.
FIG. 17 is a cross-sectional view showing a schematic configuration of an image scanner which is an example of an image reading apparatus to which the present invention is applied. In this figure, reference numeral 401 is a document to be read, 402 is a document table on which the document 401 is placed, 403 is a document illumination system for irradiating light to the document 401, 404 is an optical axis of reflected light, and 405 is a reading element. For example, a CCD (Charge Coupled Device), 406 represents an imaging lens, and 407 represents a total reflection mirror. Reference numeral 408 denotes a photoelectric conversion unit comprising the CCD 405, lens 406, mirror 407, etc., 409 and 410 are pulleys for sub-scanning driving, 411 is a wire, 418 is a driving motor (motor), and 412 is an image scanner. Represents the housing.

  A photoelectric conversion unit 408 for reading an original uses a means for fixing a driving motor 418 to a housing 412 and transmitting a driving force of an electric motor such as a wire 411 and pulleys 409 and 410, and a sub scanning direction of the original 401. Driven by. At this time, the original 401 on the original table 402 is illuminated by a reading illumination system 403 such as a fluorescent lamp, and the reflected light beam (the optical axis is indicated by reference numeral 404) is folded back by a plurality of mirrors 407 and passed through an imaging lens 406. An image of the original 401 is formed on a light receiving portion of an image sensor such as a CCD 405. The photoelectric conversion unit 408 scans the entire surface of the document 401 to read the entire document. A sensor 413 indicating the reading start position is installed below the end of the document 401, and the photoelectric conversion unit 408 rises from the home position A to the reading start position B so as to be in a constant speed steady state. The reading is started after the point A is reached.

  Therefore, in the present embodiment, drive control of the photoelectric conversion unit 408 is performed by the motor control device of the present invention. That is, the motor 418 is provided with an FG output similarly to the rotating body drive control device described with reference to FIG. 10, and outputs a pulse in accordance with the rotation of the motor. In addition to the motor FG, the encoder can be provided on a rotating body driven by the motor 418. Then, based on the output of the encoder, the motor 418 is controlled by the control system using the speed discriminator as described in FIGS.

  According to this embodiment, the present invention is used for drive control of the photoelectric conversion unit 408 (drive control of the pulley 409 that is a rotating member related to drive of the photoelectric conversion unit 408), so that it is standard even for a plurality of speed conditions. The drive system can be driven with high accuracy under optimum conditions as in the case of the above speed, and a high-quality read image can be obtained.

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. For example, the circuit configuration of a control system using a speed discriminator can be designed as appropriate. Further, as described above, the present invention can be similarly implemented in a control system using both speed discriminating (control by the speed discriminator method) and pulse phase control (PLL control). An encoder can also be provided on an appropriate member.

  In the image forming apparatus, the present invention can be applied to drive control of various rotating bodies, and the present invention can be applied regardless of the image forming method. The number of image carriers is also arbitrary, and a color image forming apparatus can be configured by appropriately combining the number of image carriers and the presence or absence of an intermediate transfer member. In addition, the device configuration of the image forming unit and other units is arbitrary. Of course, the image forming apparatus is not limited to a printer, and may be a copier, a facsimile machine, or a multifunction machine having a plurality of functions. Further, the present invention can be applied not only to a color image forming apparatus but also to a monochrome apparatus.

  In the image reading apparatus, the configuration of each part is arbitrary. For example, the present invention can be applied to a configuration in which a reading unit such as a CCD is fixedly arranged and which controls driving of a traveling body equipped with a light source and a mirror. is there.

It is a block diagram which shows the prior art example of the control system using a speed discriminator. It is a wave form diagram for demonstrating operation | movement of a speed discreet part. It is a circuit diagram which shows the structural example of an integral amplifier part. It is a graph which compares and shows the change of the gain by the difference in speed, and a phase characteristic. It is a block diagram which shows the structure of the control system using the speed discriminator which concerns on this invention. It is a circuit diagram which shows the structural example of the integral amplifier part used for the control system. It is a circuit diagram which shows another structural example of the integral amplifier part used for the control system. It is a circuit diagram which shows the structural example of the integral amplifier part which has two input resistance. It is a block diagram which shows the structure of the control system using the integral amplifier part of FIG. It is a perspective view which shows the Example of the rotary body drive control apparatus to which this invention is applied. It is a perspective view which shows another Example of the rotary body drive control apparatus to which this invention is applied. It is sectional drawing which shows schematic structure of a laser printer provided with the rotary body drive control apparatus which concerns on this invention. It is an enlarged view showing a schematic configuration of a transfer unit of the laser printer. 1 is a cross-sectional view illustrating a schematic configuration of a color copying machine including a rotating body drive control device according to the present invention. FIG. 2 is a cross-sectional view showing a main configuration of a color image forming apparatus using a belt-like photoconductor provided with a rotating body drive control device according to the present invention. 1 is a cross-sectional view showing a schematic configuration of a tandem type color copying machine including a rotating body drive control device according to the present invention. It is sectional drawing which shows schematic structure of an image reading apparatus provided with the rotary body drive control apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reference clock 2 Speed discriminating part 3 Integration amplifier part 4 PWM oscillation part 5 DC motor drive device 6 Motor 11 Standard speed 12 Target speed 13 Speed ratio calculation part 14 Integration amplifier part 15 Gain selection part 20 Endless belt (belt-shaped rotating body) )
31 Motor 36 Encoder 60 Transfer conveyor belt (belt-shaped rotating body)
101 Photosensitive belt (belt-shaped rotating body)
219 Intermediate transfer belt (belt-shaped rotating body)
301 belt-shaped intermediate transfer body (belt-shaped rotating body)
408 Photoelectric conversion unit (moving body)
409 Pulley (Rotating body)
418,501 Motor 505 Drum-shaped rotating body

Claims (19)

A drive control apparatus having a plurality of target speeds including a standard speed, wherein the DC motor is controlled at least by speed control using a speed discriminator, and controls a rotating body driven by the motor. In
A rotating body drive control device characterized in that a gain of feedback control is determined in accordance with a ratio between a standard speed and a target speed. The number of control gains is set to be smaller than the number of target speeds, and a gain smaller than the optimum gain calculated by the ratio of the standard speed to the target speed is selected from the set gains and used. The rotating body drive control device according to claim 1, wherein: 3. The rotating body drive according to claim 2, wherein the set gain includes a standard gain that is optimum for a standard speed, and the standard gain is used as a control gain when the target speed is a standard speed. Control device. As the control gain, two control gains are set, a standard gain that is optimal for a standard speed and a low gain that corresponds to the slowest target speed,
The rotating body drive control device according to claim 2, wherein the standard gain is used when the target speed is equal to or higher than the standard speed, and the low gain is used when the target speed is slower than the standard speed. The operational amplifier is configured to output a gain of the feedback control, and an input resistance value of the operational amplifier is changed in accordance with a ratio between a standard speed and a target speed. The rotating body drive control device according to Item 1. 6. The rotating body drive control device according to claim 5, wherein an input resistance of the operational amplifier is a variable resistance. The number of resistors each having a different resistance value that can be selected as the input resistance of the operational amplifier is provided for the number of target speeds, and a resistor having a resistance value corresponding to the ratio between the standard speed and the target speed is selected from the resistance group and used. The rotating body drive control device according to claim 5, wherein: An image forming apparatus comprising the rotating body drive control device according to claim 1. The image forming apparatus according to claim 8, wherein the rotating body driven and controlled by the rotating body drive control device is an image carrier. The image forming apparatus according to claim 9, wherein the image carrier is a photosensitive drum. The image forming apparatus according to claim 9, wherein the image carrier is a photosensitive belt. The image forming apparatus according to claim 9, wherein the image carrier is an intermediate transfer drum. The image forming apparatus according to claim 9, wherein the image carrier is an intermediate transfer belt. 9. The image forming apparatus according to claim 8, wherein the rotator driven and controlled by the rotator drive controller is a recording material carrier. The image forming apparatus according to claim 14, wherein the recording material carrier is a transfer drum. The image forming apparatus according to claim 14, wherein the recording material carrier is a transfer conveyance belt. Having a plurality of image carriers, each color image formed on each image carrier is sequentially superimposed and transferred onto the image carrier or a recording material carried on the recording material carrier to form a color image. The image forming apparatus according to claim 12, wherein the image forming apparatus is an image forming apparatus. An image reading apparatus having a moving body that moves by mounting an optical member, and the rotating body that is driven and controlled by the rotating body drive control device is a member that is related to driving of the moving body. The image forming apparatus according to 8. An image reading apparatus comprising the rotating body drive control device according to claim 1, wherein the image reading apparatus includes a moving body that moves by mounting an optical member, and is driven and controlled by the rotating body drive control device. An image reading apparatus, wherein the rotating body is a member related to driving of the moving body.

Images