JP2005141442A - Drive control device and method, image forming device, image reader, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce, even when using a low-resolution, inexpensive sensor, the maximum amount of deviation from a desired position such as a belt, which deviation could occur after a joint between marks or the like has been passed. <P>SOLUTION: When the joint or the like between linear scales 108 exists in the detection area of a surface sensor 109, a discontinuous part appears in the output pulses thereof. When the discontinuous part does not exist, feedback control is effected using multiplied pulses obtained by multiplying each output pulse up to 64 times. When the discontinuous part exists, dummy pulses taking the place of the multiplied pulses are used to effect feedback control. The feedback control effected using such multiplied pulses has the effect of enhancing the apparent resolution of even a low-resolution surface sensor. As a result, the maximum amount of deviation between the position of the belt 106 and the desired position, which could occur immediately after the period of the discontinuous part has ended, can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a drive control device that feedback-controls the drive of a drive control target member based on detection results of a plurality of marks provided on the drive control target member that moves endlessly or an endless move member that moves endlessly along therewith, The present invention relates to a drive control method, an image forming apparatus, an image reading apparatus, and a program.

  On the rotation axis of the drive control target member or the rotation axis of the endless moving member that moves endlessly therewith, a plurality of marks that are continuous over the rotation direction are provided, and the detection result is fed back, and the drive control target member A method of performing speed control and position control is known (see Patent Document 1). In this method, the eccentricity of the rotating shaft provided with a plurality of marks, the error of the mark installation position with respect to the rotating shaft, and the like influence the endless moving speed (hereinafter simply referred to as “speed”) of the drive control target member. ) And an endless movement position (hereinafter simply referred to as “position”), an error occurs, and accurate feedback control cannot be performed. Therefore, conventionally, a method has been put into practical use in which a mark is directly provided on the surface of the drive control target member or the surface of the endless moving member, and the mark is detected to perform feedback control. According to this method, since the influence of the eccentricity of the rotating shaft or the deviation of the mark installation position does not appear in the mark detection result, accurate feedback control can be performed.

JP-A-9-229957

However, when the mark is directly provided as described above, if the drive control target member is used over time, a part of the mark is often scratched or soiled. Marks with such scratches and dirt cannot be accurately detected by the mark detection means.
Further, when a mark is provided by attaching an encoder scale or the like on which a plurality of marks are formed in advance to the surface or the like of the drive control target member, there is a joint. In general, when a scale is pasted, both ends of the scale are separated so as not to overlap each other, and therefore, the interval between two marks sandwiching the joint portion is usually wider than the mark interval between other portions. Therefore, accurate mark detection by the mark detection means cannot be performed even at the joint portion.
In this way, if there are scratches, dirt, or joints in a plurality of consecutive marks, a discontinuous portion is generated in the mark detection signal where the interval between the signal portions corresponding to the marks is outside a predetermined range. It will be. If such a discontinuous portion exists in the mark detection signal, feedback control becomes unstable during the discontinuous portion period and a certain period thereafter, and stable drive control cannot be performed.

  Therefore, the present applicant has proposed a method for correcting the feedback signal for a discontinuous portion in the mark detection signal in Japanese Patent Application No. 2003-326822. In this prior application, as an example, a method of performing feedback control using a substitute signal instead of a discontinuous portion in a mark detection signal is cited. In this case, for example, a signal portion (continuous portion) other than the discontinuous portion in the mark detection signal detected in the past is used as the substitute signal. According to this method, it is possible to perform the same feedback control as the continuous portion even for the discontinuous portion in the mark detection signal, and as a result, stable drive control can be performed.

However, the present inventors have clarified that the following problems occur only by the method of the prior application. Hereinafter, this defect will be described.
Using a high-resolution mark sensor as the mark detection means results in an increase in manufacturing cost. Therefore, it is desirable to use an inexpensive low-resolution mark sensor when putting the method of the prior application into practical use. When a low-resolution mark sensor is used, there is a limit to the mark interval that can be detected depending on the resolution. Specifically, for example, when a mark is directly provided on the surface of a drive control target member that moves endlessly at a speed of 282 mm / s, the limit of the mark interval is about 160 μm. In this case, the position of the drive control target member can be grasped only in units of 160 μm. Therefore, for example, when only one mark is detected more than the target number of marks, the position of the drive control target member is actually detected even when the position of the drive control target member is advanced by only 1 μm from the target position. Is determined to be 160 μm ahead of the target position. Therefore, when a low-resolution mark sensor is used, the accuracy of causing the position of the drive control target member to follow the target position is lower than that of a high-resolution mark sensor.
Even in a device using such a low-resolution mark sensor, stable feedback control can be performed with respect to the period of the discontinuous portion by applying the method of the prior application. However, in the method of the prior application, during the period of the discontinuous portion, a mark detection signal or the like (dummy signal) in the past continuous portion is pseudo-feedback as a mark detection signal in the discontinuous portion. Therefore, the actual position of the drive control target member cannot be grasped for the period of the discontinuous portion. In addition, the speed of the drive control target member varies due to various errors in the drive system. Therefore, it is impossible to grasp how much the actual endless moving position immediately after the discontinuous period ends or how far the target end position is advanced.

FIG. 20 is a graph showing an outline for explaining the position of the drive control target member grasped based on the mark detection signal from the mark sensor before and after the period of the discontinuous portion. In this graph, time is plotted on the horizontal axis, and the position (relative position) of the drive control target member with respect to the target position is plotted on the vertical axis.
As shown in the drawing, during the period A of the continuous portion, feedback control following the target position is performed based on the mark detection signal from the mark sensor. Even in this example using a low-resolution mark sensor, the position of the drive control target member during this period A can be kept within a range of about 160 μm around the target position by feedback control. On the other hand, in the period B of the discontinuous portion, feedback control is performed using the dummy signal as described above. During the period B, as described above, the position of the drive control target member cannot be grasped. Here, it is assumed that the position (relative position) of the drive control target member with respect to the target position does not change during the period B. On the other hand, when the period B of the discontinuous portion ends, feedback control is performed again based on the mark detection signal from the mark sensor. At this time, the result of the feedback control is not instantaneously reflected in the position change of the drive control target member due to the influence of the torque applied to the drive system. Therefore, immediately after the period B of the discontinuous portion ends, the position of the drive control target member may be greatly deviated from the target position.

The magnitude of this deviation is determined by the timing at which the period B of the discontinuous portion starts and ends during the speed fluctuation of the drive control target member.
More specifically, when the period B starts when the speed of the drive control target member is the slowest, the endless movement position of the drive control target member is in a state most delayed with respect to the target position as shown in the figure. . Here, it is assumed that the period B ends when the speed of the drive control target member is the fastest. Immediately after the end of the period B, as described above, the result of the feedback control is not reflected in the position change of the drive control target member. Therefore, after the period B ends, the speed of the drive control target member gradually decreases, and the position of the drive control target member is further delayed from the target position. As a result, even in this example in which the position of the drive control target member with respect to the target position can be within the range of about 160 μm as described above, the position of the drive control target member is immediately after the period B ends. The maximum delay is about 480 μm from the target position. When such a large delay occurs, the feedback control is performed to correct the delay. As a result, the speed of the drive control target member rapidly changes, resulting in a problem that stable drive control cannot be performed. In addition, when such a large delay occurs, there also arises a problem that a period C2 required to stably follow the position of the drive control target member to the target position becomes long.

  On the other hand, if a high-resolution mark sensor is used, more accurate feedback control is possible. Therefore, the error range of the position of the drive control target member with respect to the target position can be narrowed compared to the above example using the low-resolution mark sensor. That is, in the graph shown in FIG. 20, in the period A and the period C2, the amplitude of the waveform indicating the change in the position of the drive control target member with respect to the target position can be reduced. As a result, the maximum delay amount D2 between the position of the drive control target member and the target position immediately after the period B ends can be reduced. Therefore, if a high-resolution mark sensor is used, it is possible to suppress the above problems. However, as described above, such a high-resolution mark sensor results in an increase in manufacturing cost. Therefore, a new technique that can suppress the above-described problem even when an inexpensive low-resolution mark sensor is used is desired. .

  In the above description, the case where the position of the drive control target member is delayed with respect to the target position immediately after the end of the period B has been described as an example. In this case, the amount of advancement can be maximized immediately after the end of the period B. The period B starts when the speed of the drive control target member is the fastest and the period when the speed of the drive control target member is the slowest. This is the case where B ends.

  The present invention has been made in view of the above background, and an object of the present invention is a drive that can suppress the above problems even when a low-resolution and inexpensive sensor is used as the mark detection means. A control apparatus, a drive control method, an image forming apparatus, an image reading apparatus, and a program are provided.

In order to achieve the above object, the invention of claim 1 is continued at predetermined intervals over the endless movement direction of the drive control target member that moves endlessly or the endless movement member that moves endlessly as the drive control target member moves endlessly. In the drive control device that detects a plurality of marks provided by the mark detection means and feedback-controls the drive of the drive control target member using the mark detection signal obtained thereby, the mark detection signal is multiplied to a predetermined multiple. When it is determined that there is no discontinuous portion in which the interval of the signal portion corresponding to the mark is outside the predetermined range in the mark detection signal or in the multiplied signal, the multiplication means for generating the multiplied signal, When feedback control is performed using the multiplied signal and it is determined that the discontinuous portion exists, an alternative signal is used instead of the multiplied signal. It is characterized in that it has a feedback control means for performing feedback control.
According to a second aspect of the present invention, in the drive control apparatus of the first aspect, as the multiplying means, a phase comparison is made between the fed back multiplied signal and the mark detection signal before the multiplication, and the multiplied signal is obtained using the phase comparison result. The multiplication circuit to be generated is used.
According to a third aspect of the present invention, in the drive control device according to the first or second aspect, the feedback control means switches between feedback control using the multiplied signal and feedback control using the alternative signal. Control switching means for performing a switching process for the feedback control means using the alternative signal by the control switching means, after determining that the discontinuous portion is present, It is characterized in that an operation stabilization period set longer than the time required until the multiplication operation by the multiplication means is stabilized is added to a period until it is determined that there is no discontinuous portion. Is.
According to a fourth aspect of the present invention, in the drive control apparatus of the third aspect, the determination as to whether or not the discontinuous portion exists is made in the mark detection signal or the multiplied signal obtained within a predetermined sampling time. The operation is performed depending on whether or not the number of signal portions corresponding to the mark is smaller than a specified number, and the operation stabilization period is set to a period corresponding to an integral multiple of the sampling time.
According to a fifth aspect of the present invention, in the drive control device according to the third or fourth aspect of the present invention, the drive control device further includes a program storage medium storing a program that causes the computer functioning as the feedback control unit to function as the control switching unit. The switching process is performed by executing the program.
According to a sixth aspect of the present invention, in the drive control device according to the third or fourth aspect, the control switching unit performs the switching process by transmitting a switching signal to the feedback control unit. Is.
The invention according to claim 7 is a plurality of drive control target members that move endlessly or a plurality of endless movement members that endlessly move in accordance with the endless movement of the drive control target members so as to continue at predetermined intervals. In a drive control method in which a mark is detected by a mark detection means and the drive of the drive control target member is feedback controlled using a mark detection signal obtained thereby, a multiplied signal is generated by multiplying the mark detection signal by a predetermined value. When it is determined that there is no discontinuous portion in which the interval of the signal portion corresponding to the mark is outside the predetermined range in the mark detection signal or in the multiplied signal, the multiplication signal is used. When feedback control is performed and it is determined that the discontinuous portion exists, the feedback control is performed using an alternative signal instead of the multiplied signal. It is characterized in that it has a feedback control step of performing.
According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising: a drive control target member that moves endlessly; and a drive control unit that performs drive control of the drive control target member. 2, 3, 4, 5 or 6 drive control devices are used.
According to a ninth aspect of the present invention, there is provided a traveling body that irradiates light on a document surface or receives reflected light of the light irradiated on the document surface, and travels along the traveling body along the document surface. An image reading apparatus comprising: a drive control target member that moves endlessly provided on a drive force transmission path that transmits a drive force for driving; and a drive control unit that performs drive control of the drive control target member. As a means, the drive control device according to claim 1, 2, 3, 4, 5 or 6 is used.
Further, the invention of claim 10 is a plurality of drive control target members that move endlessly or a plurality of endless movement members that endlessly move along with the endless movement of the drive control target members so as to continue at predetermined intervals. In a program for causing a computer to function in a drive control device that detects a mark by mark detection means and feedback-controls driving of the drive control target member using a mark detection signal obtained thereby, the mark detection signal includes Or, there is no discontinuous portion in which the interval of the signal portion corresponding to the mark is outside the predetermined range in the multiplied signal obtained by multiplying the signal by a multiplying means provided in the drive control device. When it is determined that feedback control is performed using the multiplied signal, and when it is determined that the discontinuous portion exists As a feedback control means for performing feedback control using the alternate signals in place of 該逓 doubled signal, and characterized by causing the computer to function.

  According to the first to tenth aspects of the present invention, when a mark is scratched or dirty, or a joint is present in the detection region of the mark detection means, a discontinuous portion appears in the mark detection signal. When it is determined that this discontinuous portion does not exist, feedback control is performed using a multiplied signal obtained by multiplying the mark detection signal by a predetermined value. On the other hand, when it is determined that a discontinuous portion exists, feedback control is performed using an alternative signal in place of the multiplied signal. Thus, by performing feedback control using the multiplied signal obtained by multiplying the mark detection signal, even if the mark detection means has a low resolution, the effect of increasing the apparent resolution can be obtained. Therefore, for the continuous portion in the mark detection signal, the error range of the endless movement position of the drive control target member relative to the target position can be reduced. As a result, as in the case of using the high-resolution mark detection means, the maximum delay amount or the maximum advance amount between the endless movement position and the target position of the drive control target member that can occur immediately after the period of the discontinuous portion ends. Can be small. Therefore, it is possible to suppress a rapid fluctuation in the endless moving speed of the drive control target member that may occur immediately after the discontinuous portion period ends. In addition, the period required for the endless moving speed of the drive control target member to become stable after the discontinuous portion period ends can be shortened.

  As described above, according to the first to tenth aspects of the present invention, even when a low-resolution and low-cost sensor is used as the mark detection means, the endless drive control target member that may occur immediately after the discontinuous period ends. An excellent effect is obtained in that rapid fluctuations in the moving speed are suppressed, and a period required until the endless moving speed of the drive control target member is stabilized after the discontinuous portion period ends can be shortened.

Hereinafter, an embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram showing a configuration of a belt driving device which is a rotating body driving device including a belt 106 as a drive control target member. The belt 106 is an endless belt wound around at least two shafts, and corresponds to a photoreceptor belt, an intermediate transfer belt, and a direct transfer belt, which will be described later.
A driving roller 101 is fixed to the rotating shaft of the gear 100, and a gear 103 is fixed to the rotating shaft of the motor 102 which is a DC motor. When the motor 102 as a drive source is rotationally driven, the rotational force is transmitted to the drive roller 101 via the gear 103 and the gear 100, and the drive roller 101 is rotationally driven. A belt 106 is wound around the driving roller 101 and the driven rollers 104 and 105, and a constant tension is applied by the tension roller 107. A linear scale 108 on which a plurality of marks are formed along the surface movement direction (endless movement direction) is attached to the surface of the belt 106. Further, a surface sensor 109 made of a reflective photosensor as a mark detection means is provided so as to face the linear scale 108. By reading the mark on the linear scale 108 by the surface sensor 109, the surface moving position which is the endless moving position of the belt 106 and the surface moving speed which is the endless moving speed are measured.

FIG. 2 is a schematic configuration diagram showing a configuration of a drum driving device which is a rotating body driving device including a drum 126 as a drive control target member. The drum 126 corresponds to a photosensitive drum and a transfer drum described later.
A driving pulley 125 is fixed to a rotating shaft 124 of the gear 122, and a gear 123 that meshes with the gear 122 is fixed to a rotating shaft of a motor 121 that is a DC motor as a driving source. When the motor 121 is rotationally driven, the rotational force of the motor 121 is rotationally driven via the gears 122 and 123. A timing belt 131 is wound around the driving pulley 125 and the driven pulley 128, and a constant tension is applied by the tension pulley 130. A drum 126 is attached to the driven pulley 128 via a shaft 127 so that the coaxiality is maintained. A linear scale 108 similar to that shown in FIG. 1 is attached to the surface of the drum 126 along its circumferential direction. Further, a surface sensor 109 made of a reflective photosensor as a mark detection means is provided so as to face the linear scale 108. By reading the mark on the linear scale 108 by the surface sensor 109, the surface moving position which is the endless moving position of the drum 126 and the surface moving speed which is the endless moving speed are measured.

  In this embodiment, the linear scale 108 is attached to one end portion of the surface of the belt 106 or the drum 126, but may be attached to the center portion or the back surface of the surface. In this embodiment, the belt 106 and the drum 126, which are drive control target members, are directly marked. However, the drive roller 101 and the driven rollers 104 and 105 that move endlessly as the surface of the belt 106 moves, It may be provided on an endless moving member such as a driven pulley 128 that moves endlessly as the surface of 126 moves. In this embodiment, the belt 106 is provided with a plurality of marks by attaching the linear scale 108 in which a plurality of marks are formed in advance so as to be continuous at a predetermined interval to the belt 106. The mark may be directly written.

3A is an enlarged view of a joint portion of the linear scale 108 attached to the belt 106 in FIG. 1 or the drum 126 in FIG. On the linear scale 108, a plurality of marks 108a are written at equal intervals in the direction of surface movement of the belt 106 and the drum 126 (hereinafter referred to as “rotor” as appropriate) by a technique such as laser irradiation. Specifically, a plurality of marks 108a are written on an aluminum tape with an interval of about 160 μm. It is possible to write the marks 108a at narrower intervals, but the surface sensor 109 used in this embodiment is a low-resolution and inexpensive sensor using a photodiode as a light receiving element, and therefore cannot be made narrower. The surface sensor 109 irradiates the linear scale 108 with light output from a light emitting element (not shown), and receives the reflected light with a light receiving element (not shown). The portion where the mark 108a is not written has a strong reflected light, and the written portion has a weak reflected light. Therefore, the mark 108a on the linear scale 108 is recognized based on the difference in the amount of received light. Here, the aluminum tape is used as the base material of the linear scale 108, but other materials may be used.
When the mark is provided by sticking the linear scale 108 as in the present embodiment, the sticking is usually made so that both ends of the linear scale 108 do not overlap as shown in FIG. For this reason, the interval between the two marks located between the joints is much wider than the interval between the marks on the linear scale 108. Therefore, the mark detection signal portion corresponding to the joint portion becomes a discontinuous portion in which the interval of the signal portion corresponding to the mark is outside a predetermined range, and a normal signal cannot be obtained.

FIG. 3B is an enlarged view of a portion with the dirt 133 on the linear scale 108 attached to the belt 106 in FIG. 1 or the drum 126 in FIG.
When a mark is provided on the surface side of the rotating bodies 106 and 126 as in this embodiment, dirt such as toner may adhere to the mark. When the dirt adheres in this way, the reflected light of the portion becomes weak, and this portion becomes a discontinuous portion where the interval between the signal portions corresponding to the marks is outside the predetermined range. Accordingly, a normal signal cannot be obtained as in the case of the joint. The same applies to not only dirt but also marks that are damaged.

FIG. 4 is a block diagram showing a configuration of a control system that digitally controls the angular displacements of the motors 102 and 121 based on the output signal of the surface sensor 109.
In FIG. 4, reference numeral 135 denotes a microcomputer including a microprocessor 136, a read only memory (ROM) 137, and a random access memory (RAM) 138. The microprocessor 136, the read only memory (ROM) 137, and the random access memory (RAM) 138 are connected via a bus 143. Reference numeral 139 denotes a command generator that outputs a target command signal that commands the target angular displacement of the motors 102 and 121. This command generator 139 is also connected to the bus 143. Reference numeral 142 denotes a detection interface device that processes an output pulse (mark detection signal) of the surface sensor 109 and converts it into a digital numerical value. The detection interface device 142 includes a counter that counts the output pulses of the surface sensor 109 every predetermined sampling time, and sequentially transmits the count value of the counter to the microcomputer 135 via the bus 143. Reference numeral 140 denotes a motor driving interface. The motor driving interface 140 is a power semiconductor that constitutes the motor driving device 141 based on a comparison result between a feedback signal sent from the microcomputer 135 and a target command signal sent from the command generating device 139. For example, a pulse signal (control signal) for operating the transistor is output. The motor driving device 141 operates based on the pulse signal from the motor driving interface 140 and controls the voltage applied to the motors 102 and 121.
In the present embodiment, the detection interface device 142, the microcomputer 135, the command generation device 139, and the motor drive interface 140 constitute a feedback control means.

  FIG. 5 is a control block diagram showing a schematic configuration of the feedback control system of the present embodiment. In this block diagram, the controller 150 and the subtracter 155 are configured by the motor drive interface 140 shown in FIG. The plant 151 includes the motors 102 and 121 shown in FIGS. 1 and 2, the overall configuration (drive device) that drives the belt 106 and the drum 126, and the surface sensor 109. Further, the multiplication unit 152 and the counter 153 are configured by the detection interface device 142 shown in FIG. The correction processing unit 154 includes a microcomputer 135. The reference signal ref input to the subtracter 155 corresponds to the target command signal output from the command generator 139.

  In such a feedback control system, when a control signal is output from the controller 150 to the motor drive device 141 in the plant 151, the motors 102 and 121 are rotationally driven at a rotational speed corresponding to the control signal. When this rotational driving force is transmitted to the belt 106 and the drum 126 in the plant 151 and the belt 106 and the drum 126 move on the surface, the linear scale 108 moves endlessly. The mark 108 a on the linear scale 108 is continuously detected by the surface sensor 109 in the plant 151, so that an output pulse is output from the surface sensor 109. When this output pulse is input to the multiplication unit 152 configured by the detection interface device 142, the frequency of the output pulse is multiplied by 64 times. The pulse multiplied by 64 (multiplied pulse) in this way is input to the counter 153 configured by the detection interface device 142. The counter 153 counts the number of input multiplied pulses every predetermined sampling time. The count value is input to the correction processing unit 154 configured by the microcomputer 135. The correction processing unit 154 outputs a feedback signal to the subtractor 155 after performing correction processing described later. The subtractor 155 subtracts the feedback signal (multiplied pulse or dummy pulse described later) output from the correction processing unit 154 from the reference signal ref that is input to the subtractor 155, that is, the target command signal (target pulse number). The result is output to the controller 150. The controller 150 configured by the motor driving interface 140 generates a control signal for controlling the motor driving device 141 from the subtraction result, and outputs the control signal to the motor driving device 141 of the plant 151. As a result, the belt 106 and the drum 126 are subjected to feedback control so that the surface movement position follows the target position corresponding to the target command signal generated by the command generator 139.

  FIG. 6 is a functional block diagram showing a multiplier circuit that constitutes the multiplier 152. This multiplier circuit uses a PLL (Phase-Locked-Loop). Specifically, when an output pulse from the surface sensor 109 is input, this output pulse is input to the phase comparator 160. The phase comparator 160 also receives the frequency-divided pulse from the frequency divider 163. The phase comparator 160 compares the phase of the output pulse from the surface sensor 109 and the frequency-divided pulse from the frequency divider 163, and outputs a voltage proportional to the phase difference. This output is input to the loop filter 161 to be smoothed. The output of the loop filter 161 is input to a VCO (Voltage-Controlled-Oscillator) 162. In the VCO 162, the frequency of the pulse to be output is controlled according to the voltage output from the loop filter 161. In this embodiment, the VCO 162 outputs a multiplied pulse having a frequency 64 times that of the output pulse from the surface sensor 109. The multiplied pulse is input to the counter 153 as described above, and is fed back to the frequency divider 163. The frequency divider 163 divides the multiplied pulse from the VCO 162 to a frequency that is the reciprocal of the multiplied number, that is, 1/64. This divided pulse is input to the phase comparator 160.

Next, a case where a discontinuous portion occurs in the output pulse from the surface sensor 109 due to the presence or absence of a scratched or dirty portion of the linear scale 108 or a joint of the scale in the detection region of the surface sensor 109 will be described.
FIG. 7 is a graph showing the number of pulses counted for each sampling time before and after the discontinuous portion when the correction processing by the correction processing unit 154 is not performed. In FIG. 7, the horizontal axis represents time, and the vertical axis represents the number of pulses counted for each sampling time for output pulses from the surface sensor 109. The number of pulses for each sampling time is within the range of the normal region a1 in the figure for the continuous portion. However, when a scratched or dirty part of the linear scale 108 or a joint of the scale comes to the detection area of the surface sensor 109, the surface sensor 109 cannot detect the mark 108a, and the number of pulses decreases as shown in the figure. Therefore, in the present embodiment, the correction processing unit 154 is configured to determine that there is an error when the number of pulses for each sampling time enters the range of the non-normal area a2 that deviates from the normal area a1. The normal area a1 can be arbitrarily determined by the designer.

  As an example of a method for determining the number of threshold pulses indicating the boundary between the normal region a1 and the non-normal region a2, the sampling time is A, the speed of the belt 106 or the drum 126 is B, the resolution is C, and the mark interval When (the pitch of the mark 108a) is D, a theoretical value is obtained from the calculation of A × B × C ÷ D, and a designer determines a fluctuation range that can occur due to a normal disturbance, and further determines the fluctuation range. The normal region a1 as shown in FIG. The “margin” here can be determined, for example, from the distribution of experimental data.

  The number of pulses Pn1, Pn2, and Pn3 when no scratched or dirty part or joint is present in the detection area of the surface sensor 109 falls within the range of the normal area a1 in FIG. However, when a part with scratches or dirt or a joint part comes to the detection area of the surface sensor 109, the number of pulses falls to Pn4 and Pn5 and falls within the range of the non-normal area a2 in FIG. When these pulse numbers Pn4 and Pn5 (discontinuous portions) are used as they are as feedback signals, it is determined that the driving of the belt 106 and the drum 126 has been delayed although the belt 106 and the drum 126 are appropriately driven, Drive control is performed to increase the speed. When the discontinuous portion ends, it is determined that the driving of the belt 106 and the drum 126 is fast because the speed has been increased at the error portion (Pn6), and the drive control for decreasing the speed is performed. By such a series of driving operations, the feedback control system itself creates fluctuations that do not exist originally, and large fluctuations are produced in the driving of the belt 106 and the drum 126.

Therefore, in the present embodiment, it is determined whether or not the number of pulses counted for each sampling time is within the normal region a1. If it is determined that it is not within the normal region a1, that is, within the non-normal region a2, the control is continued using a dummy pulse as an alternative signal entering the normal region a1 instead of the counted number of pulses. To do.
FIG. 8 is a flowchart showing a control flow in the feedback control system of the present embodiment. The surface sensor 109 detects the mark 108a on the linear scale 108 (S1). The frequency of the output pulse from the surface sensor 109 is multiplied by 64 in the multiplier 152 (S2). Then, the counter 153 counts the number of multiplied pulses for each sampling time (S3). The correction processing unit 154 determines whether or not the count value output from the counter 153 is within a specified range, that is, whether or not it is equal to or greater than the number of threshold pulses (S4).

If the count value is within the specified range, the count value is normal, and the count number measured by the counter is additionally stored in the memory (check1) in addition to the count number accumulated so far (S5). Here, the memory (check 1) means a specific storage area of the RAM 138 shown in FIG. Thereafter, the counter is reset (S6), and feedback control is performed using the additionally stored memory (check1) value (S7). Note that the initial value of the memory (check1) is zero.
On the other hand, when it is determined in S4 that the count value is not within the specified range, the count value is an error value corresponding to a joint portion, a scratched portion, a dirty portion, or the like. Therefore, in this embodiment, the number of dummy pulses is additionally stored in the memory (check 1) as a count value (S8). Thereafter, the counter is reset (S6), and feedback control is performed using the value of the memory (check1) in which the number of dummy pulses is additionally stored (S7).

Next, an example of how to determine the dummy pulse used in the correction processing in the correction processing unit 154 will be described with reference to FIG.
In FIG. 7, until the number of pulses Pn3, normal feedback control is performed in which the count value indicating the number of pulses is used as it is as a feedback signal. The number of pulses at this time is stored in the RAM 138, for example. When the count value of the output pulse from the surface sensor 109 is in the normal area a1, the value of the number of pulses stored in the RAM 138 is updated. When the number of pulses Pn4 within the non-normal area a2 is counted, instead of the number of pulses Pn4, the number of pulses stored in the RAM 138 (last updated number of pulses Pn3) is used as the pulse of the dummy pulse. This is used as the number Pn4a and is used as a feedback signal. In the control loop, the number of pulses Pn4a is handled as counted. The same applies to the number of pulses Pn5. At this time, the last updated pulse number Pn3 is held without updating the value of the pulse number stored in the RAM 138. When the number of pulses Pn6 entering the normal region a1 is counted, the normal feedback control described above is returned to. By performing such correction processing, the feedback control system is continued without being unstable even if there are joints, scratches, or dirt on the detection region of the surface sensor 109.
Note that the method of determining the dummy pulse is not limited to this, and another method described in, for example, the prior application may be adopted.

  As described above, according to the present embodiment, the number of pulses is counted every predetermined sampling time for the multiplied pulse obtained by multiplying the output pulse from the surface sensor 109 by 64 times. Therefore, the number of pulses counted within the sampling time can be significantly increased as compared with the case where no multiplication is performed. As a result, highly accurate feedback control can be performed. As a result, the maximum amount of deviation between the position of the belt 106 or the drum 126 and the target position immediately after the discontinuous portion period ends can be reduced.

  More specifically, as shown in FIG. 10A, in the output pulse before multiplication, when one pulse exists so as to extend over the separation timing T0 of the sampling times T1 and T2, the rising portion of the pulse When counting the number of pulses, the one pulse is counted at the sampling time T1. In such a case, if the sampling time T1 is started just at the rising edge of the pulse, an advance position error corresponding to approximately 3/4 of the mark interval occurs at the sampling time T1. Further, if the sampling time T2 ends just at the rising edge of the pulse, a delay position error corresponding to approximately 1/4 of the mark interval occurs at the sampling time T2. On the other hand, when a multiplied pulse obtained by multiplying the output pulse is used as in the present embodiment, as shown in FIG. 10B, the position error that can occur at the sampling times T1 and T2 is at most 1 of the mark interval. This is equivalent to / 64. As a result, as shown in FIG. 11, the error range of the position of the belt 106 or the drum 126 relative to the target position, that is, the amplitude of the waveform in the period A or the period C1, is compared with the case shown in FIG. Can be made smaller. As a result, the maximum delay amount D1 with respect to the target position of the belt 106 or the drum 126 that may occur immediately after the discontinuous portion period B ends is compared with the maximum delay amount D2 when the output pulse is not multiplied, as shown in the figure. Can be small.

[Modification]
Next, a modification of the above embodiment will be described.
In the above embodiment, since the multiplier 152 uses a multiplier circuit using a PLL, the loop filter 161 is included. For this reason, there is a delay time corresponding to the time constant of the loop filter 161. As a result of the existence of such a delay time, an abnormal output pulse, that is, an output pulse having a number of pulses that falls within the range of the non-normal region a2 is input from the surface sensor 109 to the multiplier 152, and then to the multiplier 152. Even if a normal output pulse, that is, an output pulse having the number of pulses that falls within the range of the normal region a1, is input, a multiplied pulse of a predetermined multiple (64 times) cannot be generated immediately. Therefore, even if a normal output pulse is output from the surface sensor 109, the normal multiplication pulse is not output from the multiplication unit 152 for a period corresponding to the delay time thereafter, and appropriate feedback control is performed. I can't.

FIG. 12 is a timing chart for explaining the relationship between the output pulse output from the surface sensor 109 and the operation of the multiplier 152. In this timing chart, the upper part shows the output pulse output from the surface sensor 109, the middle part shows the frequency (schematic) of the multiplication pulse outputted from the multiplication unit 152, and the lower part shows the output signal of the timer described later.
If there are joints, scratches, or soiled parts in the detection area of the surface sensor 109, a discontinuous part in which no mark is detected is generated in the output pulse from the surface sensor 109 as shown in the figure. At this time, it is assumed that the multiplication pulse is not output from the multiplication unit 152 that multiplies the output pulse. In some cases, a multiplication pulse having a different frequency may be output from the multiplication unit 152. When the period B of the discontinuous portion ends, the output pulse is output again from the surface sensor 109, but the multiplier 152 is immediately multiplied by a predetermined factor (64 times) due to the time constant of the loop filter 161. The multiplied pulse cannot be output. That is, even after the period B of the discontinuous portion ends, an appropriate multiplied pulse is not output from the multiplier 152 during the period E in the figure. For this reason, if the number of pulses used in the correction processing unit 154 is switched from the number of dummy pulses to the number of multiplied pulses immediately after the period B of the discontinuous portion is completed, appropriate feedback control may not be performed. There is.

FIG. 13 is a flowchart showing the flow of control in the feedback control system according to this modification.
In this modification, when the correction processing unit 154 determines that the count value of the multiplied pulse output from the counter 153 is not within the specified range (S4), the timer is started. This timer is constituted by a timer circuit (not shown) provided outside the microcomputer 135 shown in FIG. Therefore, the microcomputer 135 that is determined not to be within the specified range transmits a measurement signal to the timer circuit, and the timer circuit that receives the measurement signal measures the time until the set time is reached. As shown in FIG. 12, the timer circuit outputs an L level output signal to the microcomputer 135 when time measurement is started, and outputs an H level output signal after reaching the set time. After that, while it is determined that the count value is within the specified range, the timer is not restarted even if it is determined that the count value is not within the specified range. In this modification, the set time is measured using a timer circuit, but other means may be used as long as the time can be measured.

  When the correction processing unit 154 determines that the count value is within the specified range (S4), the correction processing unit 154 determines whether the timer has reached the set time based on the output signal from the timer circuit. Judgment is made (S9). In this determination, if it is determined that the timer has not yet reached the set time, the feedback control using the dummy pulse is continued as in the case where it is determined in S4 that the count value is not within the specified range ( S8, S6, S7). Thereafter, when it is determined that the timer has reached the set time (S9), the routine returns to normal feedback control (S5, S6, S7). Therefore, if the set time of the timer is set to be equal to or longer than the time obtained by adding the period E shown in FIG. 12 to the period B, appropriate feedback control can be performed without being affected by the delay time of the multiplier 152. Can do. The set time may be equal to or longer than the time obtained by adding the period E shown in FIG. 12 to the period B, but in this modification, the set time is set to be a time F corresponding to an integral multiple of the sampling time. . As a result, the reference clock used for measuring the sampling time can be used also in the timer circuit, and the clock generation circuit can be omitted in realizing the feedback control system. In this modification, the period B is also a time corresponding to an integral multiple of the sampling time, so the time obtained by subtracting the time corresponding to the period B from the time F (operation stable period) is also an integral multiple of the sampling time. Is equivalent to

  In the present modification, the microcomputer 135 constituting the correction processing unit 154 switches between performing feedback control using the multiplied pulse or performing feedback control using the dummy pulse based on the output signal of the timer circuit. It functions as a control switching means for performing the switching process. Specifically, a program for causing the microprocessor 136 constituting the microcomputer 135 to function as the control switching means is stored in the ROM 137 as a program storage medium, and the microprocessor 136 reads out and executes the program. Switching processing is performed.

In this modification, the switching process is realized by software, but may be realized by hardware. For example, the detection interface device 142 that processes the output pulses of the surface sensor 109 and converts them into digital numerical values may function as the control switching means. In this case, for example, the detection interface device 142 determines the discontinuous portion from the input output pulse from the surface sensor 109 in the same manner as the correction processing unit 154, and after the discontinuous portion period B starts, The output pulse is not input to the multiplier 152 until the set time is reached.
Further, the feedback control using the dummy pulse can be continued until the time corresponding to the set time is reached without using the timer circuit. As a specific example, the light receiving level of the surface sensor 109 before and after the discontinuous portion is as shown by a solid line in the upper part of FIG. When this light reception level signal is passed through a low-pass filter, it becomes a low-frequency signal such as a one-dot chain line shown in the upper part of FIG. Then, the signal level of the low-frequency signal is compared with a predetermined threshold level S to generate a comparison result signal shown in the middle stage of FIG. The comparison result signal is H level if the signal level of the low frequency signal is equal to or higher than the predetermined threshold level S, and is L level if the signal level is lower than the predetermined threshold level S. The comparison result signal is delayed by a delay circuit or the like, and then the delayed signal is output to the correction processing unit 154. Due to this delay, the L level termination time of the delayed signal input to the correction processing unit 154 is made to coincide with the end of the period F shown in FIG. If the surface sensor 109 configured in this way is used, the correction processing unit 154 determines whether or not the delay signal is at the L level instead of the determination of S9 shown in FIG. Without using it, it is possible to continue the feedback control using the dummy pulse until the surface sensor 109 reaches a time corresponding to the set time.

[Example 1]
Next, an embodiment in which the above-described feedback control system is applied to a color copying machine as an image forming apparatus (hereinafter, this embodiment is referred to as “embodiment 1”) will be described.
FIG. 15 is a schematic configuration diagram illustrating the color copying machine according to the first embodiment.
The apparatus main body 10 includes a photosensitive drum 12 which is a latent image carrier as an image carrier, slightly to the right in the drawing from the center in the outer case 11. Around the photosensitive drum 12, a rotary developing device 14, an intermediate transfer unit 15, and a cleaning device as developing means are sequentially arranged in the rotational direction (counterclockwise direction) indicated by an arrow from a charger 13 installed thereon. A device 16, a static eliminator 17 and the like are arranged. On these charger 13, rotary developing device 14, cleaning device 16, and static eliminator 17, an optical writing device as an exposure unit, for example, a laser writing device 18 is installed. The rotary developing device 14 includes developing devices 20A, 20B, 20C, and 20D having developing rollers 21 that respectively store toners of yellow, magenta, cyan, and black, and rotate around a central axis to rotate each color. The developing units 20A, 20B, 20C, and 20D are selectively moved to a developing position that faces the outer periphery of the photosensitive drum 12.

In the intermediate transfer unit 15, an endless intermediate transfer member as an image carrier, for example, an intermediate transfer belt 24, is wound around a plurality of rollers 23, and the intermediate transfer belt 24 is brought into contact with the photosensitive drum 12. A transfer device 25 is installed inside the intermediate transfer belt 24, and a transfer device 26 and a cleaning device 27 are installed outside the intermediate transfer belt 24. The cleaning device 27 is provided so as to be able to contact with and separate from the intermediate transfer belt 24.
The laser writing device 18 receives an image signal of each color from the image reading device 29 via an image processing unit (not shown), and the laser beam L that is sequentially modulated by the image signal of each color is uniformly charged in the photosensitive drum 12. To expose the photosensitive drum 12 to form an electrostatic latent image on the photosensitive drum 12.
The image reading device 29 color-separates and reads the image of the document G set on the document table 30 provided on the upper surface of the apparatus body 10 and converts it into an electrical image signal. The recording medium conveyance path 32 conveys a recording medium such as a sheet from right to left. A registration roller pair 33 is installed in the recording medium conveyance path 32 in front of the intermediate transfer unit 15 and the transfer device 26, and a conveyance belt 34, a fixing device 35, and a discharge roller are provided downstream of the intermediate transfer unit 15 and the transfer device 26. A pair 36 is arranged.

The apparatus main body 10 is placed on the sheet feeding device 50. A plurality of paper feed cassettes 51 are provided in multiple stages in the paper feed device 50, and any one of the paper feed rollers 52 is selectively driven to send a recording medium from any one of the paper feed cassettes 51. . This recording medium is conveyed to the recording medium conveyance path 32 through the automatic paper feeding path 37 in the apparatus main body 10.
A manual feed tray 38 is provided on the right side of the apparatus main body 10 so as to be openable and closable. A recording medium inserted from the manual feed tray 38 is conveyed to the recording medium conveyance path 32 through a manual paper feed path 39 in the apparatus main body 10. A paper discharge tray (not shown) is detachably attached to the left side of the apparatus main body 10, and the recording medium discharged by the paper discharge roller pair 36 through the recording medium conveyance path 32 is accommodated in the paper discharge tray.

In this color copying machine, when making a color copy, when a document G is set on the document table 30 and a start switch (not shown) is pressed, a copying operation is started. First, the image reading device 29 separates and reads the image of the document G on the document table 30.
At the same time, the recording medium is selectively sent out from the paper feeding cassette 51 in the paper feeding device 50 by the paper feeding roller 52, and this recording medium hits the registration roller pair 33 through the automatic paper feeding path 37 and the recording medium conveyance path 32. Stop.
The photosensitive drum 12 rotates in the counterclockwise direction, and the intermediate transfer belt 24 rotates in the clockwise direction by the rotation of the driving roller among the plurality of rollers 23. The photosensitive drum 12 is uniformly charged by the charger 13 as it rotates, and the laser beam modulated by the image signal of the first color applied from the image reading device 29 to the laser writing device 18 through the image processing unit. Irradiation from the laser writing device 18 forms an electrostatic latent image.

The electrostatic latent image on the photosensitive drum 12 is developed by the first color developing device 20A of the rotary developing device 14 to become a first color image, and the first color image on the photosensitive drum 12 is intermediately transferred by the transfer device 25. Transferred to the belt 24. The photosensitive drum 12 is cleaned by the cleaning device 16 after the transfer of the image of the first color to remove the residual toner, and is neutralized by the static eliminator 17.
Subsequently, the photosensitive drum 12 is uniformly charged by the charger 13, and laser light modulated by the image signal of the second color applied from the image reading device 29 to the laser writing device 18 through the image processing unit is laser-induced. Irradiation from the writing device 18 forms an electrostatic latent image. The electrostatic latent image on the photoconductive drum 12 is developed by the second color developing device 20B of the rotary developing device 14 to become a second color image, and the second color image on the photoconductive drum 12 is intermediate transferred by the transfer device 25. The image is transferred onto the belt 24 so as to overlap with the first color image. The photosensitive drum 12 is cleaned by the cleaning device 16 after the transfer of the image of the second color to remove the residual toner, and is neutralized by the static eliminator 17.

Next, the photosensitive drum 12 is uniformly charged by the charger 13, and laser light modulated by an image signal of the third color applied from the image reading device 29 to the laser writing device 18 through the image processing unit is a laser. Irradiation from the writing device 18 forms an electrostatic latent image. The electrostatic latent image on the photosensitive drum 12 is developed by the third color developing device 20C of the rotary developing device 14 to become a third color image. The third color image on the photosensitive drum 12 is intermediated by the transfer device 25. The first color image and the second color image are superimposed and transferred onto the transfer belt 24. The photosensitive drum 12 is cleaned by the cleaning device 16 after the transfer of the image of the third color to remove the residual toner, and is neutralized by the static eliminator 17.
Further, the photosensitive drum 12 is uniformly charged by the charger 13, and laser light modulated by the image signal of the fourth color applied from the image reading device 29 to the laser writing device 18 through the image processing unit is written into the laser beam. Irradiation from the device 18 forms an electrostatic latent image. The electrostatic latent image on the photosensitive drum 12 is developed by the developing device 20D of the fourth color of the rotary developing device 14 to become an image of the fourth color, and the image of the fourth color on the photosensitive drum 12 is intermediately transferred by the transfer device 25. A full-color image is formed on the belt 24 by being superimposed on the first color image, the second color image, and the third color image.
The photosensitive drum 12 is cleaned by the cleaning device 16 after the transfer of the image of the fourth color to remove the residual toner, and is neutralized by the static eliminator 17.

Then, the registration roller pair 33 is rotated at a timing to send out a recording medium, and a full color image on the intermediate transfer belt 24 is transferred to the recording medium by the transfer device 26. This recording medium is transported by the transport belt 34, the full color image is fixed by the fixing device 35, and is discharged to the discharge tray by the discharge roller pair 36. Further, the intermediate transfer belt 24 is cleaned by a cleaning device 27 after the transfer of the full-color image to remove residual toner.
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 drum 12 and transferred onto the intermediate transfer belt 24. And then transferred to a recording medium at once. In the case of forming a two-color superimposed image, two different single-color images are sequentially formed on the photosensitive drum 12, transferred onto the intermediate transfer belt 24, and then transferred to a recording medium at a time.

In such a color copying machine, the driving accuracy of the photosensitive drum 12 and the intermediate transfer belt 24 as an image carrier and the conveying belt 34 as a recording material conveying member greatly affects the quality of the final image, and the higher these values are. Accurate driving is desired.
Therefore, in the first embodiment, the photosensitive drum 12 uses the driving device shown in FIG. 2, and the intermediate transfer belt 24 and the conveying belt 34 are driven using the driving device shown in FIG. The drive is controlled by. Accordingly, the driving accuracy of the image carrier and the driving accuracy of the recording material conveying member are improved, and a high-quality image can be obtained.

[Example 2]
Next, an embodiment in which the above-described feedback control system is applied to a color copier as an image forming apparatus (hereinafter, this embodiment is referred to as “embodiment 2”) as in the first embodiment will be described.
FIG. 16 is a schematic configuration diagram illustrating a color copying machine according to the second embodiment.
In the color copying machine according to the second embodiment, a photosensitive member 60 as a latent image carrier as an image carrier is formed on an outer surface of a closed loop Ni (nickel) belt base material, such as an organic optical semiconductor (OPC). 1 is a photosensitive belt in which the photosensitive layer is formed into a thin film. The photoreceptor 60 is supported by three photoreceptor transport rollers 61, 62, and 63, and is rotated in the direction of arrow A by a drive motor (not shown).
Around the photosensitive member 60, in the order of rotation of the photosensitive member 60 indicated by an arrow A, a charger 64, an exposure optical system (hereinafter referred to as LSU) 65 as an exposure unit, a developing device for each color of black, yellow, magenta, and cyan. 66 to 69, an intermediate transfer unit 70, a photoreceptor cleaning means 71, and a static eliminator 72 are provided.
The charger 64 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 photoreceptor 60 facing the charger 64 to give a uniform charging potential.

The LSU 65 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) with the modulated signal. , The exposure light beam 73 is obtained, and the photoconductor 60 is scanned by the exposure light beam 73 to sequentially form electrostatic latent images corresponding to the image signals of the respective colors on the photoconductor 60.
The seam sensor 74 detects a seam of the photoconductor 60 formed in a loop shape. When the seam sensor 74 detects the seam of the photoconductor 60, the seam of the photoconductor 60 is avoided and each color is detected. The timing controller 75 controls the light emission timing of the LSU 65 so that the electrostatic latent image forming positions are the same.

Each of the developing devices 66 to 69 stores toner corresponding to each developing color, and is selectively applied to the photoconductor 60 at a timing corresponding to the electrostatic latent image corresponding to the image signal of each color on the photoconductor 60. By abutting and developing the electrostatic latent image on the photoconductor 60 with toner to form an image of each color, a full color image is formed by a four-color superimposed image.
The intermediate transfer unit 70 includes a transfer drum 76 as an intermediate transfer member in which a belt-like sheet made of a conductive resin or the like is wound around a metal base tube of aluminum or the like, and an intermediate transfer member cleaning in which rubber or the like is formed in a blade shape. The intermediate transfer member cleaning unit 77 is separated from the intermediate transfer member 76 while the four-color superimposed image is formed on the intermediate transfer member 76.
The intermediate transfer member cleaning unit 77 contacts the intermediate transfer member 76 only when the intermediate transfer member 76 is cleaned, and removes toner remaining without being transferred from the intermediate transfer member 76 to the recording paper 78 as a recording medium. The recording paper 78 is sent one by one from the recording paper cassette 79 to the paper transport path 81 by the paper feed roller 80.

The transfer unit 82 serving as a transfer unit transfers a full-color image on the intermediate transfer member 76 to the recording paper 78. The transfer unit 83 is formed of a conductive rubber or the like in a belt shape, and the intermediate transfer member 76 is provided on the intermediate transfer member 76. A transfer device 84 that applies a transfer bias for transferring a full color image to the recording paper 78 to the intermediate transfer member 76, and the recording paper 78 is electrostatically applied to the intermediate transfer member 76 after the full color image is transferred to the recording paper 78. The separator 85 is configured to apply a bias to the intermediate transfer member 76 so as to prevent sticking.
The fixing device 86 includes a heat roller 87 having a heat source therein and a pressure roller 88. The full-color image transferred onto the recording paper 78 is rotated between the heat roller 87 and the pressure roller 88 so as to sandwich the recording paper. Accordingly, pressure and heat are applied to the recording paper 78 to fix the full color image on the recording paper 78 to form a full color image.

The operation of the color copying machine 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 60 and the intermediate transfer member 76 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 64 from a power supply device (not shown), and the charger 64 uniformly charges the surface of the photoreceptor 60 to about −700V.
Next, after the seam sensor 74 detects the seam of the photoconductor 60 and after a predetermined time has passed so as to avoid the seam of the photoconductor 60, the laser beam corresponding to the black image signal from the LSU 65 is applied to the photoconductor 60. The exposure light beam 73 is irradiated, and the photosensitive member 60 loses the charge of the portion irradiated with the exposure light beam 73 to form an electrostatic latent image.
On the other hand, the black developing device 66 is brought into contact with the photoreceptor 60 at a predetermined timing. The black toner in the black developing device 66 is given a negative charge in advance, and the black toner adheres only to the portion (electrostatic latent image portion) where the charge disappears due to the irradiation of the exposure light beam 73 on the photoreceptor 60. Development is performed by a so-called negative positive process.
The black toner image formed on the surface of the photoreceptor 60 by the black developing device 66 is transferred to the intermediate transfer member 76. Residual toner that has not been transferred from the photoconductor 60 to the intermediate transfer body 76 is removed by the photoconductor cleaning means 71, and the charge on the photoconductor 60 is removed by the charge eliminator 72.

Next, the charger 64 uniformly charges the surface of the photoreceptor 60 to about −700V. Then, after the seam sensor 74 detects the seam of the photoconductor 60 and after a predetermined time has passed so as to avoid the seam of the photoconductor 60, the photoconductor 60 is exposed to a laser beam corresponding to the cyan image signal from the LSU 65. The photosensitive member 60 is irradiated with the light beam 73 and the charge of the portion irradiated with the exposure light beam 73 disappears, and an electrostatic latent image is formed.
On the other hand, a cyan developing device 67 contacts the photoconductor 60 at a predetermined timing. The cyan toner in the cyan developing device 67 is given a negative charge in advance, and the cyan toner adheres only to the portion (electrostatic latent image portion) where the charge has disappeared due to the irradiation of the exposure light beam 73 on the photoreceptor 60. Development is performed by a so-called negative-positive process.
The cyan toner image formed on the surface of the photoconductor 60 by the cyan developing device 67 is transferred onto the intermediate transfer member 76 so as to overlap the black toner image. Residual toner that has not been transferred from the photoconductor 60 to the intermediate transfer body 76 is removed by the photoconductor cleaning means 71, and the charge on the photoconductor 60 is removed by the charge eliminator 72.

Next, the charger 64 uniformly charges the surface of the photoreceptor 60 to about −700V. Then, after the seam sensor 74 detects the seam of the photoconductor 60 and after a certain time has passed so as to avoid the seam of the photoconductor 60, the photoconductor 60 is exposed to a laser beam corresponding to the magenta image signal from the LSU 65. The photosensitive member 60 is irradiated with the light beam 73 and the charge of the portion irradiated with the exposure light beam 73 disappears, and an electrostatic latent image is formed.
On the other hand, a magenta developing device 68 is brought into contact with the photoconductor 60 at a predetermined timing. The magenta toner in the magenta developing unit 68 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 73 on the photoreceptor 60. Development is performed by a so-called negative-positive process.
The magenta toner image formed on the surface of the photoreceptor 60 by the magenta developing unit 68 is transferred onto the intermediate transfer member 76 so as to overlap the black toner image and the cyan toner image. Residual toner that has not been transferred from the photoconductor 60 to the intermediate transfer body 76 is removed by the photoconductor cleaning means 71, and the charge on the photoconductor 60 is removed by the charge eliminator 72.

Further, the charger 64 uniformly charges the surface of the photoreceptor 60 to about −700V. Then, after the seam sensor 74 detects the seam of the photoconductor 60 and after a certain time has passed so as to avoid the seam of the photoconductor 60, the photoconductor 60 is exposed to a laser beam corresponding to the yellow image signal from the LSU 65. The photosensitive member 60 is irradiated with the light beam 73 and the charge of the portion irradiated with the exposure light beam 73 disappears, and an electrostatic latent image is formed.
On the other hand, a yellow developing device 69 is brought into contact with the photosensitive member 60 at a predetermined timing. The yellow toner in the yellow developing unit 69 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 73 on the photoreceptor 60. Development is performed by a so-called negative-positive process.
The yellow toner image formed on the surface of the photoreceptor 60 by the yellow developing unit 69 is transferred onto the intermediate transfer member 76 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 76. It is formed. Residual toner that has not been transferred from the photoconductor 60 to the intermediate transfer body 76 is removed by the photoconductor cleaning means 71, and the charge on the photoconductor 60 is removed by the charge eliminator 72.

In the full-color image formed on the intermediate transfer member 76, the transfer unit 83 that has been separated from the intermediate transfer member 76 until then contacts the intermediate transfer member 76, and a high voltage of about +1 kV is applied to the transfer device 84 (FIG. (Not shown), the transfer device 84 collectively transfers the recording paper 78 conveyed along the paper conveyance path 81 from the recording paper cassette 79.
Further, a voltage is applied from the power supply device so that an electrostatic force that attracts the recording paper 78 is applied to the separator 85, and the recording paper 78 is peeled off from the intermediate transfer member 76. Subsequently, the recording paper 78 is sent to the fixing device 86, where the full color image is fixed by the nipping pressure between the heat roller 87 and the pressure roller 88 and the heat of the heat roller 88, and the paper is discharged by the paper discharge roller pair 89. It is discharged to the tray 90.

  Further, residual toner on the intermediate transfer member 76 that has not been transferred onto the recording paper 78 by the transfer unit 82 is removed by the intermediate transfer member cleaning means 77. The intermediate transfer member cleaning unit 77 is in a position separated from the intermediate transfer member 76 until a full-color image is obtained. After the full-color image is transferred to the recording paper 78, the intermediate transfer member cleaning unit 77 comes into contact with the intermediate transfer member 76 and is on the intermediate transfer member 76. Remove residual toner. The full color image formation for one sheet is completed by the series of operations described above.

In such a color copying machine, the driving accuracy of the photoconductor belt 60, the transfer drum 76, and the transfer belt 83 greatly affects the quality of the final image. In particular, high-precision driving of the photoconductor belt 60 and the transfer belt 83 is desired. .
Therefore, in the second embodiment, the photosensitive belt 60 and the transfer belt 83 use the driving device shown in FIG. 1, and the transfer drum 76 uses the driving device shown in FIG. Has been. Accordingly, the driving accuracy of the image carrier and the driving accuracy of the recording material conveying member are improved, and a high-quality image can be obtained. This is performed based on the above-described position control method of the rotating body.

Example 3
Next, an embodiment in which the above-described feedback control system is applied to a color copier as an image forming apparatus (hereinafter, this embodiment is referred to as “embodiment 3”) as in the first embodiment will be described.
FIG. 17 is a schematic configuration diagram illustrating a color copying machine according to the third embodiment.
The third embodiment shows an application example to a tandem image forming apparatus. In the third embodiment, a plurality of image forming units 221Bk that respectively form images of a plurality of colors, for example, black (hereinafter referred to as Bk), magenta (hereinafter referred to as M), yellow (hereinafter referred to as Y), and cyan (hereinafter referred to as C). 221M, 221Y, and 221C are arranged in a vertical direction, and the image forming units 221Bk, 221M, 221Y, and 221C are respectively image bearing members 222Bk, 222M, 222Y, and 222C made of drum-shaped photosensitive members, and charging devices (for example, contact devices) (Charging device) 223Bk, 223M, 223Y, 223C, developing device 224Bk, 224M, 224Y, 224C, cleaning device 225Bk, 225M, 225Y, 225C.
The photoconductors 222Bk, 222M, 222Y, and 222C are arranged in the vertical direction so as to face the endless direct transfer belt (conveyance transfer belt) 226, and are driven to rotate at the same peripheral speed as the direct transfer belt 226. The photoreceptors 222Bk, 222M, 222Y, and 222C are uniformly charged by charging devices 223Bk, 223M, 223Y, and 223C, respectively, and then exposed by exposure means 227Bk, 227M, 227Y, and 227C, which are optical writing devices, respectively. An electrostatic latent image is formed.

The optical writing devices 227Bk, 227M, 227Y, and 227C drive the semiconductor laser by the semiconductor laser driving circuit based on the image signals of Y, M, C, and Bk, respectively, and the laser beams from the semiconductor laser are polygon mirrors 229Bk, 229M, and 229Y. 229C is deflected and scanned, and the respective laser beams from the polygon mirrors 229Bk, 229M, 229Y, and 229C are imaged on the photosensitive members 222Bk, 222M, 222Y, and 222C via an unillustrated fθ lens and mirror, thereby providing a photosensitive member. The 222Bk, 222M, 222Y, and 222C are exposed to form an electrostatic latent image.
The electrostatic latent images on the photoreceptors 222Bk, 222M, 222Y, and 222C are developed by the developing devices 224Bk, 224M, 224Y, and 224C, respectively, and become Bk, M, Y, and C toner images. Accordingly, the charging devices 223Bk, 223M, 223Y, 223C, the optical writing devices 227Bk, 227M, 227Y, 227C and the developing devices 224Bk, 224M, 224Y, 224C are Bk, M, Y on the photosensitive members 222Bk, 222M, 222Y, 222C. , C constitutes an image forming means for forming each color image (toner image).

On the other hand, transfer paper such as plain paper and OHP sheet is fed to a registration roller 231 along a transfer paper transport path from a paper feeding device 230 configured at the bottom of the present embodiment and configured using a paper feed cassette. The registration roller 231 directly transfers the transfer paper to the first color image forming unit (image forming unit that first transfers the image on the photoconductor onto the transfer paper) 221Bk in synchronization with the toner image on the photoconductor 222Bk. And the photosensitive member 222Bk.
The direct transfer belt 226 is stretched over a driving roller 232 and a driven roller 233 arranged in the vertical direction, and the driving roller 232 is driven to rotate by a driving unit (not shown) so that the direct transfer belt 226 is photoreceptors 222Bk, 222M, 222Y, 222C. Rotate at the same peripheral speed. The transfer paper sent from the registration roller 231 is directly conveyed by the transfer belt 226, and the toner images of Bk, M, Y, and C colors on the photoreceptors 222Bk, 222M, 222Y, and 222C are transferred to a transfer unit 234Bk that includes a corona discharger. 234M, 234Y, and 234C are sequentially superimposed and transferred by the action of the electric field formed by 234M, 234Y, and 234C to form a full-color image, and at the same time, it is directly electrostatically attracted to the transfer belt 226 and reliably conveyed.

  This transfer paper is gradually electrified by a separation means 236 comprising a separation charger and directly separated from the transfer belt 226, and then a full-color image is fixed by a fixing device 237, and is provided on the upper part of this embodiment by a paper discharge roller 238. The paper is discharged to the paper discharge unit 239. In addition, the photosensitive members 222Bk, 222M, 222Y, and 222C are cleaned by the cleaning devices 225Bk, 225M, 225Y, and 225C after the toner image is transferred to prepare for the next image forming operation.

In such a color copying machine, the driving accuracy of the direct transfer belt 226 greatly affects the quality of the final image, and higher accuracy driving of the direct transfer belt 226 is desired.
Therefore, in the third embodiment, the direct transfer belt 226 is driven and controlled by the above-described feedback control system using the driving device shown in FIG. Accordingly, the driving accuracy of the recording material conveying member is improved, and a high-quality image can be obtained.

Example 4
Next, an embodiment in which the above-described feedback control system is applied to a traveling body drive device of an image reading apparatus (hereinafter, this embodiment is referred to as “embodiment 4”) will be described.
FIG. 18 is a schematic configuration diagram illustrating an image reading apparatus according to the fourth embodiment. In this image reading apparatus, reference numeral 901 is a document to be read, reference numeral 902 is a document table on which the document 901 is placed, reference numeral 903 is a document illumination system for irradiating the document 901 with light, reference numeral 904 is an optical axis of reflected light, 905 Is a reading element, for example, a CCD (Charge Coupled Device), 906 is an imaging lens, and 907 is a total reflection mirror.
Reference numeral 908 denotes a photoelectric conversion unit as a traveling body including the CCD 905, the lens 906, the mirror 907, the reference numerals 909 and 910 are sub-scanning driving pulleys, the reference numeral 911 is a wire, the reference numeral 300 is a driving electric motor, Reference numeral 912 denotes a housing of the image scanner. A photoelectric conversion unit 908 for reading a document uses a means for fixing a driving motor 300 to a housing 912 and transmitting a driving force of an electric motor such as a wire 911 and pulleys 909 and 910 in the sub-scanning direction of the document 901. To drive.

At this time, the reading illumination system 903 such as a fluorescent lamp illuminates the document 901 on the document table 902, and the reflected light beam (optical axis is indicated by 904) is folded back by a plurality of mirrors 907, via the imaging lens 906. An image of the original 901 is formed on a light receiving portion of an image sensor such as a CCD 905. The photoelectric conversion unit 908 scans the entire surface of the document 901 to read the entire document.
The sensor 913 indicating the reading start position is installed below the end of the document 901, and the photoelectric conversion unit 908 rises between the home position HP and the reading start position N so as to be in a steady state at a constant velocity. It is designed to start reading after reaching the HP point.
In the fourth embodiment, the photoelectric conversion unit 908 is driven and controlled by the above-described feedback control system using the driving device shown in FIG. Therefore, the driving accuracy of the traveling body is improved, and the image reading accuracy can be increased.

The drive control of the belt 106 and the drum 126 performed by the feedback control described above can be executed using a computer.
FIG. 19 is a front view of a personal computer 1001 which is an example of a computer used for executing the drive control. A recording medium 1003 detachable from the personal computer 1001 stores a program for causing the personal computer 1001 to execute control calculations, data input / output, and the like. The personal computer 1001 can execute the feedback control described above by executing a program stored in the recording medium 1003. Examples of the recording medium 1003 include optical disks such as CD-ROMs and magnetic disks such as flexible disks. The program may be loaded into the personal computer 1001 via a communication network without using a recording medium.

  Specific examples of the program include the following. For example, in the first embodiment, the control program is for performing drive control of the photosensitive drum 12, the intermediate transfer belt 24, and the transport belt 34 by the computer. In the second embodiment, the control program is for performing drive control of the photosensitive belt 60, the transfer drum 76, and the transfer belt 83 by the computer. In the third embodiment, the control program is for performing drive control of the drive roller of the direct transfer belt 226. The fourth embodiment is a control program for performing drive control of a drive pulley that drives the photoelectric conversion unit 908 of the image reading apparatus by a computer.

As described above, the drive control device in the above-described embodiment (including the above-described modified examples and each of the above-described examples; the same applies hereinafter) is used for the endless movement of the belt 106 and the drum 126 that are drive control target members. A plurality of marks 108a provided so as to be continuous at predetermined intervals over the endless moving direction of the driving roller 101, the driven rollers 104 and 105, and the driven pulley 128, which are endless moving members accompanying the endless moving member, are surface sensors 109 that are mark detecting means. And the drive of the belt 106 and the drum 126 is feedback-controlled using an output pulse which is a mark detection signal obtained by this. The drive control device includes a detection interface device 142 that constitutes a multiplication unit 152 as a multiplication unit that generates a multiplied pulse that is a multiplied signal obtained by multiplying the output pulse by a predetermined value. Further, when it is determined that there is no discontinuous portion in the output pulse or the multiplied signal outside the predetermined range (normal region a1) of the signal portion corresponding to the mark, feedback is performed using the multiplied pulse. When the control is performed and it is determined that there is a discontinuous portion, the detection interface device 142, the microcomputer 135, and the command generation device 139 as feedback control means for performing feedback control using a dummy pulse that is an alternative signal instead of the multiplication pulse. And an interface 140 for driving the motor. By having such a configuration, as described above, even if the surface sensor 109 has a low resolution, the effect of increasing the apparent resolution is obtained, and the continuous portion in the output pulse or the multiplication pulse is obtained. The error range of the position of the belt 106 and the drum 126 with respect to the target position can be reduced. As a result, the maximum deviation amount D1 that can occur immediately after the period B of the discontinuous portion ends can be reduced. Therefore, it is possible to suppress a rapid speed fluctuation of the belt 106 and the drum 126 that may occur immediately after the discontinuous portion period B ends, and also the speed of the belt 106 and the drum 126 after the discontinuous portion period B ends. It is possible to shorten the period C <b> 1 required for the to stabilize.
Further, in the above-described embodiment, the multiplication unit 152 uses a PLL circuit that is a multiplication circuit that compares the phase of the fed back multiplied pulse and the output pulse before the multiplication, and generates the multiplied pulse using the phase comparison result. Yes. This makes it possible to generate the multiplied pulse with an inexpensive configuration.
Further, in the above embodiment, the feedback control means has a control switching means for performing a switching process for switching between feedback control using a multiplied pulse or feedback control using a dummy pulse. The period for which feedback control is performed using the dummy pulse for the feedback control means is further performed during the period B from the time when it is determined that the discontinuous portion exists until the time when the discontinuous portion is determined not to exist. It is assumed that an operation stabilization period set longer than the time E required for stabilizing the multiplication operation by the above is added. Accordingly, as described above, appropriate feedback control can be performed without being affected by the delay time of the multiplier circuit.
In the above embodiment, whether or not the discontinuous portion exists is determined by a count value that is the number of signal portions corresponding to the mark in the output pulse or the multiplied pulse obtained within a predetermined sampling time. The operation stabilization period is set to a period corresponding to an integral multiple of the sampling time. Thereby, as described above, the clock generation circuit can be omitted, and the cost can be reduced.
In the above-described embodiment, the ROM 136 is a program storage medium that stores a program that causes the microprocessor 136 serving as the computer 135 functioning as the feedback control means to function as the control switching means. The above switching process is performed by executing. By performing the switching process on the software in this way, it is not necessary to separately provide hardware that functions as the control switching unit, so that the cost can be reduced.
Further, as described in the above embodiment, the control switching unit may be configured to perform the switching process by transmitting a switching signal to the feedback control unit. Also with such a configuration, the switching process can be performed.
In addition, the color copying machine as the image forming apparatus according to the first to third embodiments includes the photosensitive drum 12, the intermediate transfer belt 24, the conveyance belt 34, the photosensitive belt 60, and the transfer belt as the drive control target members that move endlessly. 83, a transfer drum 76, a direct transfer belt 226, and drive control means for performing drive control thereof. As the drive control means, the drive control device described in the above embodiment is used. Thereby, the drive control of the drive control target member whose drive accuracy greatly affects the quality of the final image can be improved, and a high-quality image can be obtained.
The image reading apparatus according to the fourth embodiment includes a photoelectric conversion unit 908 that is a traveling body that irradiates light on a document surface or receives reflected light of light irradiated on the document surface, and the photoelectric conversion unit 908. Wires 911 and pulleys 909 and 910 that are endlessly moved drive control target members provided on a drive force transmission path for transmitting a drive force for traveling along the document surface, and drive control means for controlling the drive thereof It has. As the drive control means, the drive control device described in the above embodiment is used. Accordingly, the driving accuracy of the photoelectric conversion unit 908 can be improved, and the image reading accuracy can be increased.

  The present invention can be used without being limited to the drive control of the drive control target member in the image forming apparatus or the image reading apparatus. For example, the present invention can be applied to an ODD (Optical Disk Drive), a HDD (Hard Disk Drive), a robot, and the like. The present invention can also be applied to drive control of a rotating body provided.

The schematic block diagram which shows the structure of the belt drive device which is an example of embodiment. The schematic block diagram which shows the structure of the drum drive device which is another example of embodiment. (A) The figure which expanded the joint part of the linear scale. (B) The figure which expanded the part which became dirty on a linear scale. The block diagram which shows the structure of the control system which digitally controls the angular displacement of a motor based on the output signal of a surface sensor. The control block diagram which shows schematic structure of the feedback control system which concerns on embodiment. The functional block diagram which shows the multiplication circuit which comprises the multiplication part which comprises the feedback control system. The graph which shows the number of pulses counted for every sampling time before and behind a discontinuous part, when not performing the correction process by a correction process part. The flowchart which shows the flow of control in the feedback control system. The graph which shows the pulse number counted for every sampling time over the front and back of a discontinuous part when the correction process by the correction process part is performed. . (A) And (b) is a figure which shows the output pulse before multiplication, and the multiplication pulse after multiplication, respectively. The graph for demonstrating the position of the belt or drum with respect to a target position over the period of a discontinuous part when the same feedback control system is used. The timing chart for demonstrating the relationship between the output pulse output from a surface sensor, and the operation | movement of a multiplication part. The flowchart which shows the flow of control in the feedback control system which concerns on a modification. The graph which shows the light reception level of a surface sensor, a comparison result signal, and a multiplication signal, respectively, in order to explain other examples of composition concerning the modification. 1 is a schematic front view of a one-drum type color copying machine according to Embodiment 1. FIG. FIG. 3 is a schematic front view of a photoconductor belt type color copying machine according to a second embodiment. FIG. 5 is a schematic front view of a direct transfer belt type color copying machine according to a third embodiment. FIG. 10 is a schematic front view of an image reading apparatus according to a fourth embodiment. A front view of a personal computer which is an example of a computer used for execution of drive control in an embodiment. The graph for demonstrating the position of the belt with respect to a target position over the period of a discontinuous part in the feedback control system which does not multiply about sensor output.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Photosensitive drum 24 Intermediate transfer belt 34 Conveyance belt 60 Photosensitive belt 76 Transfer drum 83 Transfer belt 102, 121 Motor 106 Belt (drive control object member)
108 Linear Scale 108a Mark 109 Surface Sensor 126 Drum (Drive Control Target Member)
135 Microcomputer 136 Microprocessor 139 Command generator 140 Motor drive interface 141 Motor drive device 142 Detection interface device 152 Multiplier 153 Counter 154 Correction processor 155 Subtractor 160 Phase comparator 161 Loop filter 163 Frequency divider 908 Photoelectric conversion unit

Claims (10)

The mark detection means detects a plurality of marks provided so as to be continuous at a predetermined interval over the endless movement direction of the endlessly moving drive control target member or the endless movement member that moves endlessly with the endless movement of the drive control target member, In the drive control device that feedback-controls the drive of the drive control target member using the mark detection signal obtained thereby,
A multiplication means for generating a multiplied signal obtained by multiplying the mark detection signal by a predetermined value;
When it is determined that there is no discontinuous portion in the mark detection signal or in the multiplied signal where the interval between the signal portions corresponding to the marks is outside the predetermined range, feedback control is performed using the multiplied signal. And a feedback control means for performing feedback control using an alternative signal in place of the multiplied signal when it is determined that the discontinuous portion exists. The drive control apparatus according to claim 1,
A drive control device characterized in that as the multiplying means, a multiplying circuit that compares the phase of the fed back multiplied signal and the mark detection signal before multiplication and generates a multiplied signal using the phase comparison result is used. The drive control device according to claim 1 or 2,
Control switching means for performing switching processing for switching feedback control using the multiplication signal or feedback control using the alternative signal to the feedback control means,
A period of time during which feedback control is performed by the control switching unit using the substitute signal by the control switching unit is a period from when it is determined that the discontinuous part is present until the discontinuous part is not present. Furthermore, a drive control apparatus characterized in that an operation stabilization period set longer than a time required until the multiplication operation by the multiplication means is stabilized is added. The drive control apparatus according to claim 3.
Whether or not the discontinuous portion exists is determined by whether or not the number of signal portions corresponding to the mark in the mark detection signal or the multiplied signal obtained within a predetermined sampling time is less than a specified number. Done
The drive control apparatus, wherein the operation stable period is set to a period corresponding to an integral multiple of the sampling time. The drive control device according to claim 3 or 4,
A program storage medium storing a program for causing a computer functioning as the feedback control means to function as the control switching means;
The drive control device, wherein the computer performs the switching process by executing the program. The drive control device according to claim 3 or 4,
The drive control device, wherein the control switching means performs the switching process by transmitting a switching signal to the feedback control means. The mark detection means detects a plurality of marks provided so as to be continuous at a predetermined interval over the endless movement direction of the endlessly moving drive control target member or the endless movement member that moves endlessly with the endless movement of the drive control target member, In the drive control method for feedback controlling the drive of the drive control target member using the mark detection signal obtained thereby,
A multiplication step for generating a multiplied signal obtained by multiplying the mark detection signal by a predetermined value;
When it is determined that there is no discontinuous portion in the mark detection signal or in the multiplied signal where the interval between the signal portions corresponding to the marks is outside the predetermined range, feedback control is performed using the multiplied signal. And a feedback control step of performing feedback control using an alternative signal instead of the multiplied signal when it is determined that the discontinuous portion exists. A drive control target member that moves endlessly;
In an image forming apparatus including a drive control unit that performs drive control of the drive control target member,
An image forming apparatus using the drive control device according to claim 1, 2, 3, 4, 5, or 6 as the drive control means. A traveling body that irradiates light on the document surface or receives reflected light of the light irradiated on the document surface;
A drive control target member that moves endlessly provided on a driving force transmission path for transmitting a driving force for traveling the traveling body along the document surface;
In an image reading apparatus comprising drive control means for performing drive control of the drive control target member,
An image reading apparatus using the drive control device according to claim 1, 2, 3, 4, 5, or 6 as the drive control means. The mark detection means detects a plurality of marks provided so as to be continuous at a predetermined interval over the endless movement direction of the endlessly moving drive control target member or the endless movement member that moves endlessly with the endless movement of the drive control target member, In a program for functioning a computer provided in a drive control device that feedback controls the drive of the drive control target member using the mark detection signal obtained thereby,
In the mark detection signal or in the multiplied signal obtained by multiplying the mark detection signal by a multiplication means provided in the drive control device, the interval of the signal portion corresponding to the mark is not within a predetermined range. When it is determined that there is no continuous portion, feedback control is performed using the multiplied signal, and when it is determined that the discontinuous portion is present, feedback control means for performing feedback control using an alternative signal instead of the multiplied signal A program for causing the computer to function.

Images