CN100517115C - Drive control device and imaging device - Google Patents

Abstract

A drive control device controls a rotation speed of a rotatable member. A rotation drive member drives the rotatable member. A plurality of objects to be detected are provided in the rotatable member. A detector detects the objects to be detected, which are rotating with rotation of the rotatable member, and outputs a detection signal. A control part detects an angular speed of the rotatable member in accordance with the detection signal, and controls a rotation speed of the rotation drive member. The control part calculates an amount of error in intervals of the objects to be detected, and controls the rotation speed of the rotation drive member in accordance with the amount of error.

Description

Drive control device and imaging device

technical field

The present invention relates to a drive control device and an image forming apparatus, such as a facsimile machine, a printer, a copier, etc. using a rotating object, and more particularly to an image forming apparatus using an intermediate transfer member that transfers a visible image on an image carrier to the moving body at a position where the image carrier is opposite to a moving body.

Background technique

There is known an image forming apparatus, especially a color image forming apparatus, which has a plurality of developing units and an intermediate transfer belt. In this type of image forming apparatus, it is known that fluctuations in the transport speed of the intermediate transfer belt cause color shift in color images. Such fluctuations in conveying speed can be caused by fluctuations in the rotation of the drive roller that drives the intermediate transfer belt due to eccentricity of the drive roller, thermal expansion of the drive roller, load on the intermediate transfer belt during recording medium conveyance, primary The load of the intermediate transfer belt in the primary transfer bias, etc. One cause of this color shift is that a plurality of color toner images are shifted from each other when the individual color images on the intermediate transfer belt are superimposed. In order to eliminate this color shift, several methods have been proposed to reduce fluctuations in the speed of the intermediate transfer belt. As one of these methods, there is a method of correcting rotational fluctuation of a drive roller using a rotary encoder for detecting angular velocity provided on an idle roller of the intermediate transfer belt. The rotary encoder used in this method includes, for example, a disk concentrically arranged on the rotation shaft of the idler roller, and a transmission type photointerrupter sandwiching the disk. The disc is provided with a number of radially arranged slits. The photo interrupter detects the light passing through the slit to detect the pulse time of the pulse signal generated by the detection of the light. The conveyance speed of the intermediate transfer belt is calculated from the detected value for feedback control of the rotation of the driving roller.

As an imaging apparatus using the above encoder, the invention disclosed in Patent Document 1 or Patent Document 2 is known. Patent Document 1 discloses a technique of eliminating fluctuations in belt moving speed due to roller eccentricity without using a filter. According to this technique, the angular velocity information of the idle roller detected from the pulse signal of the encoder during one rotation cycle of the driving roller is stored in the first memory. Then, in the angular velocity information stored in the first memory, the velocity fluctuation component caused by the eccentricity of the drive roller is canceled out by the operation of the arithmetic circuit, and the velocity detection error component caused by the eccentricity of the idle roller is extracted, and the extracted velocity detection error component is stored in in the second memory. During imaging, the difference circuit finds the difference between the angular velocity information of the idle roller detected from the pulse signal of the encoder and the velocity detection error component stored in the second memory. Then, according to the difference data, the comparing circuit outputs a control signal to the motor driver to control the moving speed of the belt.

Patent Document 2 discloses an imaging device that can provide good control results even with an encoder having a low physical resolution. The image forming apparatus includes an image forming device for forming an image on recording paper by exposing and developing, transferring and fixing the latent image to form a latent image on a photosensitive member; a moving device for transferring processing; and a drive for rotationally driving the moving device device. The moving distance information or moving speed information of the mobile device is detected by the encoder. The position deflection or the velocity deflection is obtained from the output of the encoder, so that a predetermined operation is performed on the position deflection or the velocity deflection. The driving source is controlled according to the result of the calculation. In this imaging device, calculation is performed at a predetermined period T within the output section of the encoder.

Patent Document 1: Japanese Laid-Open Patent Application No. 2000-047547

Patent Document 2: Japanese Laid-Open Patent Application No. 2004-205717

However, if the notch width of the rotary encoder is not uniform and the pitch of the notch is not uniform, the deviation of the notch width and the notch pitch are regarded as the deviation of the speed of the intermediate transfer belt. Therefore, high levels of process accuracy and positional accuracy are required to be maintained when forming the cutouts, which increases processing costs. It is very difficult to machine the kerf with a perfectly consistent kerf spacing.

In addition, when determining the error amount of the pitch of the radially disposed notches (objects to be detected), speed fluctuations due to varying loads of the intermediate transfer belt can be included in the error amount. Therefore, the distance of the detected object must always correspond to the error amount. That is, even when the intermediate transfer belt stops, it is necessary to fully grasp the stop position between the detected objects. However, if the user removes the intermediate transfer unit and moves the intermediate transfer belt, the corresponding relationship between them becomes irregular. In addition, noise may enter the detection signal indicating the distance of the detected object when the intermediate transfer belt rotates, and if an error occurs in the detection of the detected object, the correspondence may not be obtained.

Contents of the invention

A general object of the present invention is to provide an improved and useful drive control device and image forming apparatus in which the above-mentioned problems can be eliminated.

A more specific object of the present invention is to provide a drive control device and an imaging apparatus that do not require objects to be inspected such as cutouts at uniform intervals, allow the object to be inspected to be formed at low cost, and obtain Precise control of rotating parts.

In order to achieve the above object, according to one aspect of the present invention, there is provided a drive control device for controlling the rotational speed of a rotatable component, including: rotating the drive component to drive the rotatable component; an object; a detector for detecting detected objects which rotate with the rotation of the rotatable member and outputting a detection signal; and a control unit for detecting an angular velocity of the rotatable member based on the detection signal and controlling the rotation driving member The rotation speed of the rotation speed, wherein the control unit calculates the error amount of the detected object distance, and controls the rotation speed of the rotation driving part according to the error amount.

Furthermore, according to another aspect of the present invention, there is provided an image forming apparatus comprising: an intermediate transfer belt which is a rotatable endless belt and on which a toner image is conveyed as a primary transfer image. transfer image); driving roller, which drives the intermediate transfer belt; driven roller, which rotates with the movement of the intermediate transfer belt; multiple detected objects, which rotate together with the driven roller, and detectors, which detect the detected objects and output detecting a signal, wherein the image forming apparatus transfers the primary transfer image, which has been transferred onto the intermediate transfer belt, to the recording medium, thereby forming a secondary transfer image on the recording medium, the image forming apparatus further comprising a control unit, according to the detection signal The angular velocity of the driven roller is detected, and the rotational speed of the driving roller is controlled according to the angular velocity, and the control unit calculates the error amount of the distance between the detected objects, thereby controlling the rotational speed of the driving roller according to the error amount.

According to the present invention, the error amount of the detected object pitch and the rotational speed of the rotation driving member are controlled while correcting the movement time corresponding to each pitch with a time corresponding to the error amount. Therefore, it is not necessary to make the pitches of the objects to be detected uniformly equal, which makes it possible to form the objects to be detected at low cost. Furthermore, the rotational speed of the rotary drive member can be precisely controlled.

Other objects, features and advantages of the present invention will become more apparent from the following detailed description when reading the accompanying drawings.

Description of drawings

1 is a schematic diagram of an intermediate transfer unit of a full-color imaging device according to an embodiment of the present invention;

Figure 2 is a perspective view of the driven roller shown in Figure 1, the disk and the optical sensor;

Fig. 3 is a block diagram of the control device shown in Fig. 1;

Fig. 4 is the timing diagram of the counter unit work shown in Fig. 3;

Fig. 5 is a schematic diagram illustrating the operation of the computing unit;

Fig. 6 is a schematic diagram showing the offset method of the speed fluctuation and its speed component due to the eccentricity of the drive roller;

7 is a time chart showing the control of the drive roller by the control device from the start of counting immediately after the start of the drive motor;

Fig. 8 is a flowchart of a control operation performed by the control means.

Detailed ways

Embodiments of the present invention are described below with reference to the drawings.

FIG. 1 is a schematic diagram of an intermediate transfer unit of a full-color image forming apparatus according to an embodiment of the present invention. The intermediate transfer unit shown in Fig. 1 comprises photosensitive toner drum 10Y, 10C, 10M and 10K, which are four image carriers; four developing units 11Y, 11C, 11M and 11K, which will form latent images on the corresponding photosensitive toner drum Developed as toner images having different colors from each other; and the intermediate transfer belt 12, which is rotatable in the direction of arrow A, the toner images of different colors are initially conveyed in an overlapping state. It should be noted that in the following description, the suffixes Y, M, C, and K representing the colors are omitted from the notation of constituent elements common to the respective colors of Y, M, C, and K.

The intermediate transfer belt 12 is an endless belt. In this embodiment, the above-mentioned four photosensitive toner drums 10 of yellow, cyan, magenta and black are arranged under the intermediate transfer belt 12 in parallel along the rotation direction of the intermediate transfer belt 12 . The photosensitive toner drum 10 is provided with a charging device (not shown), the above-mentioned developing unit 11, a primary conveying roller 13 constituting the primary conveying device, and a cleaning unit (not shown).

Corresponding to yellow, cyan, magenta, and black laser light of each color is irradiated by the exposure device 7 on the charging surface of the photosensitive drum 10 charged by the charging device, so that latent images are respectively formed on the surface portions of the photosensitive drum 10 irradiated by the laser. Primary conveying rollers 13 are respectively arranged relative to the photosensitive toner drums 10 , and the intermediate transfer belt 12 rotates between the primary conveying rollers 13 and the photosensitive toner drums 10 in a sandwiched state. The intermediate transfer belt 12 is supported by a driving roller 14 , a tension roller 15 and a driven roller 16 . The drive roller is rotated in the direction of arrow A by the drive motor 4 via the reduction gear 5 as a rotary drive member. The secondary transport roller 17 is disposed at a position opposite to the drive roller 14 with the intermediate transfer belt 12 sandwiched therebetween.

In the image forming apparatus according to this embodiment, when the printing operation starts, the photosensitive drum 10 in FIG. 1 rotates clockwise, and its surface is uniformly charged by the charging means. Lights corresponding to yellow, cyan, magenta, and black images are respectively irradiated from the exposure means 7 to the charging surfaces, and latent images are respectively formed on the charging surfaces. The latent images are developed by the corresponding developing units 11, and the latent images are converted into yellow, cyan, magenta, and black toner images. The toner images of the respective colors are conveyed to the intermediate transfer belt 12 rotating in the direction of arrow A by the corresponding primary conveying rollers 13 in a precisely superimposed state, so that a full-color synthetic color image is formed on the intermediate transfer belt 12 like imaging.

Conveying paper P as a recording medium is fed from a paper feeding unit 6 disposed below the photosensitive drum 10 at a predetermined timing. The composite color image carried by the intermediate transfer belt 12 is transported onto the transport paper P by the secondary transport roll 17 while the supplied transport paper P is transported between the driving roller 14 and the secondary transport roller 17 . Then, the toner image on the transfer paper P is fixed by the fixing unit 8, and ejected on a paper output tray (not shown).

The disk 19 is fixed concentrically to the driven roller 16 as a rotating disk as a rotatable member that rotates with the intermediate transfer belt 12 . A plurality of notches are formed on the disk 19 as objects to be detected. It should be noted that although the driven roller 16 is not actually shown in FIG. 1 since it is disposed on the back side of the disk 19, the driven roller 16 is drawn protruding upward from the disk 19 for simplicity.

The optical sensor 18 is arranged near the disc with a fixed distance between them. The optical sensor 18 emits measurement light to the disk 19, and receives its reflected light/transmitted light, so that a pulse-shaped detection signal is output. Then, the time period from one change point to another change point of the pulse-shaped detection signal is measured, and the angular velocity or speed of the driven roller 16 , that is, the conveyance speed of the intermediate transfer belt 12 is detected from the measured time period. Control is performed based on the detected conveyance speed so that the conveyance speed of the intermediate transfer belt 12 is kept constant. This control is performed by the control means 3 as the conveying speed control means.

It should be noted that although the cutouts 19a are provided at substantially equal intervals over the entire circumference of the disc 19 for the object to be detected, the grooves or notches (grooves) provided on the end surface or outer peripheral surface of the driven roller 16 ( notches) can also be used as the object to be detected instead of the notch 19a. When the reflective optical sensor 18 (for example, a photo reflector) is used, the detected object corresponds to a radial reflective portion formed by printing. When the transmission type optical sensor 18 (for example, a photo interrupter) is used, the detected object corresponds to the radially formed elongated through hole (cutout 19a of the disc 19). It should be noted that, for example, a magnetic sensor could be used instead of the optical sensor 18 . In this case, for example, hall elements as objects to be detected may be provided at the same positions as the above-mentioned radial reflection portions.

An optical sensor 18 is provided to the driven roller 16 in the vicinity of the drive roller 14 for determining the conveying speed of the intermediate transfer belt 12 and is configured to detect a conveying speed close to the actual speed. The length of the outer circumference of the driving roller 14 is an even multiple of the length of the outer circumference of the driven roller 16 . The following description will be made assuming that the ratio of the outer circumference length of the driving roller 14 to the outer circumference length of the driven roller 16 is 2:1.

2 is a perspective view of the driven roller 16, the disk 19, the cutout 19a formed on the disk 19 as a detected object, and the optical sensor 18 as a transmission type sensor. Emitted light from the light emitting element of the optical sensor 18 as a detector is incident on the light receiving element through the cutout (object to be detected) 19a. The voltage generated by the light receiving element is binarized by a voltage comparator, so that a pulse signal is generated as a detection signal.

FIG. 3 is a block diagram of a control device 3 which is a control unit provided in the image forming apparatus shown in FIG. 1 . As described above, the driven roller 16 generates a pulse signal of eight pulses per rotation. The control device 3 as a control unit has a counter unit 30 which counts the movement time period from rising edge to rising edge or from falling edge to falling edge of a pulse according to a clock pulse supplied by a clock 31 . The clock 31 generates periodic clock pulses with a high frequency, such as several hundred KHz to several MHz, at fixed time intervals. In this embodiment, the clock 31 is constituted by a quartz oscillator. In addition, the control device 3 includes a RAM 33 for storing the count value of the movement time period; an arithmetic unit for solving the angular velocity (moving velocity) and the difference between the angular velocity and the target velocity to obtain the velocity correction amount, by This makes it possible to obtain a constant speed; and the motor drive unit 34, which outputs a motor drive clock changed from the current speed to the motor driver 35 according to the speed correction value. A feedback coefficient (here, a PID factor) required when finding the speed correction amount is stored in the RAM 33. The motor drive unit 34 drives the drive motor 4 via a motor driver 35 . The driving force of the driving motor 4 is transmitted to the driving roller 14 through the reduction gear 5 .

FIG. 4 is a timing diagram of the operation of the counter unit 30 shown in FIG. 3 . When counting is started by the counter unit 30 at the falling edge of the detection signal of the optical sensor 18 , the count value increases one by one, for example, at the falling edge of the count clock of the clock 31 . Then, when the next falling edge of the input detection signal, an interrupt is generated, and at this time the count value (E000h in the figure) is transmitted to the register of the operation unit 32 and the count value is cleared, and a predetermined operation process is started in the operation unit 32. Then, subsequent counting starts. Here, interruption means restarting count-up by clearing the counter.

If necessary, the arithmetic unit 32 reads the count value from the register, and performs predetermined arithmetic processing described below. The count value between detection signal change points changes according to the angular velocity of the driven roller 16 . Specifically, as the angular velocity of the driven roller 16 becomes faster, the count value becomes smaller, and conversely, as the angular velocity becomes slower, the count value becomes larger. If the conveying speed of the intermediate transfer belt 12 is constant and the cutouts 19a are evenly spaced, the count value is always the same value. Also, if the slits 19 a are uniformly provided at equal intervals, the amount of change in the count value is only proportional to the conveying speed of the intermediate transfer belt 12 . However, it is impossible to make the cutouts 19a have a physically completely uniform equal pitch, and pitch errors occur to no small extent. Therefore, such an error amount is obtained according to the method described below.

FIG. 5 is a schematic diagram illustrating the operation of the arithmetic unit 32 during a period of determining an error amount. If one pulse in the detection signal output by the optical sensor 18 is set as the n-th pulse, at first, the count value of the last 16 counts including the count value currently obtained in the moving time period of 1/8 turn of the driven roller 16 is accumulated, and The angular velocity (moving speed) is obtained from the accumulated value. Then, the difference between the angular velocity and the target velocity is obtained to find a velocity correction amount, which results in a constant velocity, and velocity control is performed based on the velocity correction amount thus obtained. Subsequently, the same processing is performed on the (n+1)th pulse, and the same processing is also performed on the (n+2)th and (n+3)th pulses. Control is performed without being affected by the eccentricity of the driving roller 14 by obtaining the speed correction amount from one rotation cycle of the driving roller 14 . In addition, the control can be performed in a small time by controlling each pulse. That is, the conveyance speed of the intermediate transfer belt 12 is controlled so that the speed fluctuation of the eccentric component of the drive roller 14 is kept while the other speed components are kept constant.

FIG. 6 is a schematic diagram showing a speed fluctuation due to the eccentricity of the driving roller 14 and a method of eliminating the speed component thereof. Here, the eccentricity of the driving roller means that the cross-sectional shape of the driving roller 14 is not a perfect circle, for example, it is an ellipse, and the diameter in one direction is longer than the diameter in other directions. Eccentricity is like a shape error formed in the manufacturing process of the driving roller, and it is very difficult to form a roller without eccentricity. Generally, the eccentric movement of the roller varies according to its rotation period as shown in FIG. 6 . Therefore, the speed fluctuation caused by the eccentricity of the drive roller 14 is detected as a detection error. Therefore, detection errors due to speed fluctuations can be eliminated by obtaining an integration time of at least one revolution (per rotation in the figure) of the drive roller 14, that is, a movement time period based on a count value per rotation. Here, the length of the outer circumference of the driving roller 14 is an even multiple of the outer circumference of the driven roller 16, and the speed component caused by the eccentricity of the driving roller 14 can be eliminated according to the following method when determining the error amount described later.

First, a half cycle of one cycle of rotation of the driving roller 14 corresponds to one rotation of the driven roller 16, and its outer circumference is in a 1:2 relationship. Also, one pulse of the detection signal output by the optical sensor 18 is set to an n-th pulse, and the number of sampling intervals in one rotation cycle of the driven roller 16 is set to eight. The sampling intervals are slightly different from each other in response to a physical pitch error of the notch 19a as the detected object. Now, the movement time period of 1/8 turn of the nth pulse driven roller 16 and the movement time period of 1/8 turn of the (n+8)th pulse driven roller 16 after the subsequent half cycle of the drive roller 14 The movement time periods have the same absolute value except for the sign of the eccentricity component of the drive roller 14 being different. Therefore, the error amount of m=1 of the notch 19a can be obtained from the difference between the ideal count value and the ideal count value when the notch 19a is completely evenly spaced. The count values of +8) pulses are added and the sum is divided by 2 to obtain it. In the same way, the error amount of m=2 can be obtained from the (n+1)th pulse and the (n+9)th pulse, and continue to obtain (n+2, n+10),... , the error amount of (n+7, n+15), so as to obtain the total number of 8 corresponding to all the cutouts 19a, that is, determine the error amount from m=1 to m=8. Then, in the same way, the error amount of m=1 to m=8 is determined several times for several rotations of the drive roller 14, and the error amount obtained in this way is averaged, so the error amount can be obtained with good accuracy quantity.

FIG. 7 shows a timing chart of control of the drive roller 14 by the control unit 3 from the start of counting by the counter unit 30 immediately after the start of the drive motor 4 .

In order to perform feedback control (1) based on the moving speed (angular velocity) of one rotation cycle of the drive roller 14, a time period corresponding to one rotation cycle up to n=16 from the start of counting is waited to elapse, so no control is performed. Feedback control (1) is control for correcting errors due to gentle speed fluctuations caused by thermal expansion of the drive roller 14 and the like. When n=16 is reached, the moving velocity (angular velocity) corresponding to one rotation cycle of the driving roller 14 is first obtained, and the feedback control (1) can be performed from this time. Simultaneously, from the count values in the half cycle of the drive roller 14 for n=17 to 24 and the count values in the half cycle of the drive roller 14 for n=25 to 32, an error amount of m=1 to m=8 is determined (No. once). Also, the error amount (second time) is determined from the count value of the half cycle of n=25 to 32 and the count value of the half cycle of n=33 to 40. Further, the error amount is determined from the count value of the half cycle of n=33 to 40 and the count value of the half cycle of n=41 to 48 (third time). The amount of error obtained in this way is averaged (averaged by 3 here). Then, from n=49 until the drive motor 4 stops, the feedback control (2) is performed while sequentially correcting the amount of error found before each interruption of the counting of each notch 19a. Feedback control (2) is control for correcting errors caused by speed fluctuations due to eccentricity of the drive roller 14 . After n=48, the above-mentioned feedback control (1) and feedback control (2) are performed simultaneously.

As described above, according to the above-mentioned control, the control is not performed during the first rotation of the drive roller, the determination of the error amount is performed during the second and third rotations while the feedback control (1) is being performed, and thereafter, at Feedback control (1) and feedback control (2) are performed simultaneously during and after the fourth rotation. The determination of the error amount is not limited to the average of three times, and at least the error amount determined for the first time may be used. Furthermore, by determining the error amount for every half cycle, the error amount determination can be performed the same number of times within a half time period in the case where determination is performed every cycle.

FIG. 8 shows a flowchart of the operation of the control unit 3 of the present embodiment.

In this control operation, if the drive motor 4 is started in printing operation, etc., and stabilized at a constant speed (step S10), the count value of the count clock of the clock 31 is cleared, the counter unit 30 is allowed to be interrupted, and the counter starts to be set to Turn on (ON) (step S11). The count value of the first interrupt is not an accurate value because the start-up of the count operation and the change of the detection signal are not synchronized with each other. Therefore, the control of the first interruption is ignored (step S12), and the interruption count number n is cleared (step S13).

Then, wait for the interrupt (step S14) that counter unit 30 comes, when producing interrupt, the interrupt count increments by 1, that is, the interrupt count number n=n+1 (step S15), the count value Tc _n of the nth count value Transfer from the counter unit 30 into a register and store the value in RAM 33 . After that, check the interrupt count number n, and return to step S14 until reaching n=16, so as to repeat the process to step S17. That is, if the interrupt count number n reaches 16 (if n≥16), it is determined whether the interrupt count number n is within the range of 16≤n≤24 (step S18).

In this determining step, if within the range of 16≤n≤24, the procedure proceeds to step S19, and the angular velocity Vp1 _n [mm/s] is calculated from the count value Tc _n read in step S16. Since the count value Tc _n is the count value of every 1/8 turn of the driven roller 16 (every 1/16 turn of the drive roller 14), the count value Tc _n of one rotation period of the drive roller 14 can be accumulated to include the current The first 16 count values of the read count values are obtained as follows:

Tc _n ＝Tc _n-15 +Tc _n-14 +Tc _n-13 +...+Tc _n-2 +Tc _n-1 +Tc _n

Among them, n=16, 17, ..., 47, 48

If the minimum count time (sampling time) of the count clock is set to Δt [ms], the count time to obtain the count value Tc _n corresponding to one rotation cycle of the drive roller 14: T1 _n [ms] is as follows:

T1 _n [ms] = Tc _n × Δt

Among them, n=16, 17, ..., 47, 48

If the diameter of the driven roller 16+thickness of the intermediate transfer belt 12 is set to r [mm], the angular velocity Vp1 _n [mm/s] of the driven roller 16 is obtained as follows:

Vp1 _n [mm/s]＝r×π×2/T1 _n ×1000

Among them, n=16, 17, ..., 47, 48

If it is determined in step S18 that it is not within the range of 16≤n≤24, the process proceeds to step S20 to determine whether it is within the range of 25≤n≤32. If it is in the range of 25≤n≤32, the process enters step S21, similar to step S19, calculates the angular velocity Vp1 _n [mm/s], and calculates the error amount 1: ΔI1 _m as follows:

ΔI1 _m =Tc _s -(Tc _n-8 +Tc _n )/2

Among them, n=25, 26, ..., 31, 32

m=1,2,...,7,8

Tc _s is the ideal count value and is the count value of 1/8 revolution of the driven roller 16 with the intermediate transfer conveyor belt 12 at a constant reference speed and the spacing of the notches 19a is perfectly uniform, Tc _s is calculated as follows:

Tc _s =r×π/V _s /Δt/8×1000

Among them, r[mm] is the diameter of the driven roller + the layer thickness of the intermediate transfer conveyor belt;

V _s [mm/s] is the reference speed;

Δt[ms] is the minimum counting time of the counting clock. If it is determined at step S20 that it is not within the range of 25≤n≤32, the process goes to step S22 where it is determined whether it is within the range of 33≤n≤40. If it is within the range of 33≤n≤40, the process goes to step S23 to calculate the angular velocity Vp1 _n [mm/s] similarly to step S19, and the error amount 2: ΔI2 _m is calculated as follows:

ΔI2 _m =Tc _s -(Tc _n-8 +Tc _n )/2

Among them, n=33, 34, ..., 39, 40

m=1,2,...,7,8

If it is determined in step S22 that it is not within the range of 33≤n≤40, the process proceeds to step S24 where it is determined whether it is within the range of 41≤n≤48. If it is within the range of 41≤n≤48, the process goes to step S25 to calculate the angular velocity Vp1 _n [mm/s] similarly to step S19, and the error amount 3: ΔI3 _m is calculated as follows:

ΔI3 _m =Tc _s -(Tc _n-8 +Tc _n )/2

Among them, n=41, 42, ..., 47, 48

m=1,2,...,7,8

In addition, from the error amounts 1, 2, and 3 obtained before: ΔI1 _m , ΔI2 _m , ΔI3 _m , the error amount: ΔI _m is calculated as follows:

ΔI _m = (ΔI1 _m + ΔI2 _m + ΔI3 _m )/3

Among them, m=1,2,...,7,8

Then, the procedure proceeds to step S26, where error counts due to noise or the like are eliminated. If it is an error count, the process returns to step S13 to start the process again. In step S26, it is determined whether Vp1 _n is within ±1% limit of reference speed _Vs [mm/s]. If in the affirmative (YES), the process goes to step S27 to calculate the operating speed V1 _n [mm/s]. This calculation is performed as follows. First, obtain the difference (deviation) Ve1 _n [mm/s] to the reference speed V _s [mm/s]:

Ve1 _n [mm/s] = V _s -Vp1 _n

Among them, n=16, 17, ..., 47, 48

On the other hand, the composite velocity Vei1 _n [mm/s] for the difference is calculated as follows:

Vei1 _n [mm/s] = Ve1 _n + Ve1 _n-1

Among them, n=16, 17, ..., 47, 48

At this time, the difference Ve1 _n and the resultant velocity Vei1 _n to the difference are stored in the RAM 33 . Therefore, the operating speed V1 _n [mm/s] can be calculated as follows:

V1 _n [mm/s]=Kp1×Ve1 _n +Ki1×Vei1 _n +Kd1×(Ve1 _n -Ve1 _n-1 )+V _s

Among them, Kp1 is the proportional coefficient, Ki1 is the integral coefficient, Kd1 is the differential coefficient,

n=16, 17, ..., 47, 48

Kp1, Ki1, and Kd1 are stored in RAM 33 in advance.

On the other hand, if it is determined in step S24 that it is not within the range of 41≤n≤48, that is, in the case of n≥49, the process proceeds to step S28, and the angular velocity Vp2 _n [mm/s] is calculated from Tc _n read in step S16 . The calculation of Vp2 _n proceeds as follows. That is, first, Tc _n is sequentially corrected using ΔI _m solved in step S25.

Tcc _n =Tc _n +ΔI _m

Among them, n=49, 50,...

m=1, 2,..., 7, 8, 1, 2,...

Since the minimum counting time (sampling time) of the counting clock is Δt[ms], the counting time T2 _n [ms] is solved as follows:

T2 _n [ms] = Tcc _n × Δt

Among them, n=49, 50,...

When (diameter of driven roller 16+thickness of intermediate transfer belt 12 ) is set to r [mm], angular velocity Vp2 _n [mm/s] of driven roller 16 is solved as follows.

Vp2 _n [mm/s]＝r×π/16×T2 _n ×1000

Among them, n=49, 50,...

Then, the procedure proceeds to step S29, and similarly to step S26, error counts due to noise or the like are eliminated. If it is an error count, the process returns to step S13 to start the process again. At this time, similarly to step S26, the determination is based on the reference speed V _s [mm/s] within ±1% of the limit value. If in the affirmative (YES), the process goes to step S30 to calculate the operating speed V2 _n [mm/s]. This calculation is the same as step S27 and is performed as follows:

First, a difference (deviation) Ve2 _n [mm/s] from the reference speed V _s [mm/s] is found.

Ve2 _n [mm/s] = V _s -Vp2 _n

Among them, n=49, 50,...

The composite velocity Vei2 _n [mm/s] for the differential value is calculated as follows:

Vei2 _n [mm/s] = Ve2 _n + Ve2 _n-1

Among them, n=49, 50,...

At this time, the difference Ve2 _n and the resultant velocity Vei2 _n to the difference are stored in the RAM 33 . Therefore, the operating speed V2 _n [mm/s] can be calculated as follows:

V2 _n [mm/s]=Kp2×Ve2 _n +Ki2×Vei2 _n +Kd2×(Ve2 _n -Ve2 _n-1 )+V _s

Among them, Kp2 is a proportional coefficient, Ki2 is an integral coefficient, and Kd2 is a differential coefficient,

n=49, 50, . . .

Kp2, Ki2 and Kd2 are stored in RAM 33 in advance.

In step S31, an instruction is sent to the motor drive unit 34 so that a motor drive clock changed from the current speed is output based on the operation speed found in steps S27 and S30, thereby performing speed control of the intermediate transfer belt 12. Then, in step S33, it is determined whether the printing operation has ended. If it is determined that the printing operation has ended and the drive motor 4 should be stopped, the process proceeds to step S33, whereby the drive motor 4 is stopped, at which point the process ends.

As described above, according to the present embodiment, the following effects can be obtained.

1) Since the error amount of the notch (detected object) pitch is determined, and the error amount is corrected while controlling by obtaining the moving time of each notch for each pitch, it is not necessary to make notches at uniform and equal intervals. Therefore, a disk having cutouts can be manufactured at low cost, and the rotational speed of the drive roller (rotation drive member) can be precisely controlled.

2) Since the angular velocity is obtained from the integration time corresponding to one cycle of the driving roller, and the angular velocity of each pitch of the notch (object to be detected) is sequentially determined to control each pitch of the notch, it is possible to determine the pitch of the notch Speed fluctuations due to various loads on the intermediate transfer belt are reduced while reducing the amount of error. Therefore, the error amount of the notch pitch is not included, which allows a more precise error amount to be determined.

3) By determining the error amount every time immediately after the drive roller is started, it is not necessary to fully grasp the stop position of the cut when the intermediate transfer belt stops. Therefore, there is no problem even if the intermediate transfer unit is removed or the intermediate transfer belt is moved by a user or the like. Furthermore, even if erroneous detection is performed due to noise entering into the detection signal indicating each pitch of the cut while the intermediate transfer belt is rotating, retrying can be easily performed.

4) By determining the error amount several times and averaging the error amount, if there is still a speed fluctuation due to various loads of the intermediate transfer belt, the speed fluctuation can be smoothed. In addition, speed fluctuations generated in one rotation of the drive roller can be smoothed. Therefore, a more accurate error amount can be determined.

5) When determining the error amount, the circumference of the driving roller is set as an even multiple of the circumference of the driven roller, so that the half cycle of the driving roller and the subsequent half cycle of the driving roller can be used to eliminate the speed component caused by the eccentricity of the driving roller. Therefore, the velocity component due to the eccentricity of the drive roller can be eliminated from the error amount, which leads to more accurate determination of the error amount.

The present invention is not limited to the specifically disclosed embodiments, and various modifications and changes may be made without departing from the scope of the present invention.

The present application is based on Japanese Priority Applications No. 2005-198900 filed on July 7, 2005 and No. 2006-167992 filed on June 16, 2006, the entire contents of which are incorporated herein by reference.

Claims (11)

1. the driving control device of rotational speed of the rotatable dish of control comprises:

Rotary driving part is used to drive rotatable dish;

Be arranged on a plurality of objects to be detected in the described rotatable dish;

Detecting device, this detecting device detects above-mentioned object to be detected and output detection signal, and described object to be detected rotates along with the rotation of described rotatable dish; With

Control module detects the angular velocity of described rotatable dish according to this detection signal, and controls the rotational speed of described rotary driving part,

Wherein, described object to be detected along the circumference of rotatable dish with the equal intervals setting, and

Described control module calculates the margin of error of the spacing of described object to be detected, and controls the rotational speed of described rotary driving part according to this margin of error.

2. driving control device according to claim 1 is characterized in that described control module when revising the time interval corresponding to corresponding spacing corresponding to time of the described margin of error, controls the rotational speed of described rotary driving part.

3. driving control device according to claim 1, it is characterized in that: when described control module calculates the described margin of error, described control module from corresponding to described rotatable dish once the rotation the whole time find the solution described angular velocity, determine described angular velocity for each spacing of described object to be detected in turn, and each spacing of described object to be detected is controlled.

4. driving control device according to claim 1 is characterized in that described control module uses repeatedly the mean value of calculated value as the described margin of error.

5. driving control device according to claim 4 is characterized in that described control module calculates the described margin of error to per half rotation of described rotatable dish.

6. driving control device according to claim 1 is characterized in that described control module carries out the calculating of the described margin of error immediately after described rotatable disc spins begins.

7. driving control device according to claim 1 is characterized in that described control module carries out the calculating of the described margin of error at every turn when described rotatable disc spins begins.

8. driving control device according to claim 1, it is characterized in that: described rotatable dish is a driven voller, its rotation is to follow the rotation of the intermediate transfer parts that are arranged in the image forming apparatus, this image forming apparatus will be formed on image transfer on the photosensitive part to recording medium by the intermediate transfer parts, and described rotary driving part is the driven roller that drives described intermediate transfer parts.

9. driving control device according to claim 8, the length that it is characterized in that described driven roller excircle are the even-multiples of described driven voller excircle length.

10. driving control device according to claim 9, it is characterized in that: the length of described driven roller excircle is the twice of described driven voller excircle length, and when calculating the described margin of error, described control module is eliminated the velocity perturbation composition that described driven roller off-centre causes according to subsequently half of the described driven roller rotation of a half-sum of the rotation of described driven roller.

11. an image forming apparatus comprises:

Intermediate transfer belt, it is that rotatable endless belt and toner image are transferred on it as the first image that shifts;

Driven roller drives intermediate transfer belt;

Driven voller rotates along with the motion of described intermediate transfer belt;

With a plurality of objects to be detected that driven voller rotates, these a plurality of objects to be detected are circle-shaped and are spacedly distributed; With

Detecting device detects object to be detected and output detection signal;

Wherein said image forming apparatus will be transferred to the described first transfer image of described intermediate transfer belt and transfer on the recording medium, thereby form the secondary transferring image on described recording medium;

Described image forming apparatus further comprises control module, detects the angular velocity of described driven voller according to described detection signal, and according to the rotational speed of described angular velocity controlling and driving roller;

Described control module calculates the margin of error of the spacing of described object to be detected, thereby controls the rotational speed of described driven roller according to the described margin of error.

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