JPH10139202A - Control device for position or speed of belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect behavior of a belt with high accuracy in an optional detecting period, and improve meandering of the belt and converging performance of carrying nonuniformity by constituting a control device of a detecting means or the like to detect a position or speed of an endless belt to rotate by being stretched by plural rollers, in a prescribed detecting period. SOLUTION: When a paper sheet carrying belt 9 is carried in the arrow direction by a driving motor 22, an optical sensor 18C inputs an electric signal to a counter 24 every time when plural home position marks 9A on the surface of the paper sheet carrying belt 9 are detected, and the counter 24 counts clock pulses inputted from a clock generating circuit 23. Side end part position data of the paper sheet carrying belt 9 is inputted to a switch circuit 26 from a belt position detecting part 25, and a belt position equivalent to one round is outputted to an operation circuit 27 in the inputted timing of a trigger signal. In this way, belt position data of plural times can be gathered according to a count value set until the first and second position marks are detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for controlling the position or speed of a belt used in an image forming apparatus. And a control device for controlling the position or speed of the belt, which can detect with high accuracy in a time shorter than the rotation cycle of the belt and can control the belt at high speed.

[0002]

2. Description of the Related Art Conventionally, there has been known an image forming apparatus using an endless belt for a photosensitive member or an intermediate transfer member. The endless belt is stretched with a predetermined tension by a driving roll and a driven roll, and is conveyed in a predetermined direction based on the rotation of the driving roll. In some cases, uneven conveyance due to speed fluctuation in the conveying direction may occur.

In an image forming apparatus having a photoreceptor belt and an intermediate transfer belt, when the above-described meandering phenomenon and uneven conveyance occur during image formation, a latent image forming position on the photoreceptor belt and toner transferred to the intermediate transfer belt are changed. Image displacement occurs,
In particular, in the case of a full-color image in which a plurality of color toner images are superimposed, color unevenness or misregistration occurs in the recorded image, thereby deteriorating the image quality. For this reason, various attempts have been made to suppress the meandering phenomenon and uneven transport.

A conventional belt position control device for suppressing meandering of an endless belt is disclosed in, for example, JP-A-57-249.
No. 56, JP-A-57-138653 and JP-A-60-73561.

A belt position control device disclosed in Japanese Patent Application Laid-Open No. 57-24956 has a triangular mark formed at a side end of an endless belt, and a sensor for detecting a pass width of the triangular mark. The meandering of the endless belt is detected based on a change in the passing width of the triangular mark.

[0006] A belt position control device disclosed in Japanese Patent Application Laid-Open No. 57-138653 discloses a detection pattern formed at both ends of an endless belt with a reflectance different from the reflectance of the belt, and both ends inside the detection pattern. It has two optical sensors arranged in the vicinity, and detects the meandering of the endless belt based on changes in output signals of the two optical sensors.

A belt position control device disclosed in Japanese Patent Application Laid-Open No. Sho 60-73561 is provided with a plurality of optical devices for generating a light receiving signal by receiving a light beam for scanning a photosensitive belt at a side end of the photosensitive belt. A sensor is arranged, and when the side end of the photoreceptor belt deviates from the standard position, the meandering of the photoreceptor belt is detected by changing the output patterns of the plurality of optical sensors.

The above-mentioned JP-A-57-24956,
JP-A-57-138653 or JP-A-60-1985
According to the belt position control device disclosed in JP-A-73561, since the displacement of the mark or the belt-side end is detected by the sensor, the detection accuracy is restricted by the shape accuracy of the mark or the belt-side end. There's a problem.

In order to solve such a problem, there is a belt position control device disclosed in Japanese Patent Application Laid-Open No. 2-96774. According to this belt position control device, a plurality of marks arranged on an endless belt are each constituted by a different sign, and the difference in the meandering data of the belt detected for each of the same signs is obtained, whereby the accuracy of the mark shape is obtained. The problem caused by the problem has been solved. However, this configuration has a problem that the meandering of the belt, which occurs in a cycle shorter than one cycle of the belt, cannot be detected with high accuracy.

On the other hand, Japanese Patent Application Laid-Open No. 3-1772 discloses a method for detecting meandering of a belt having a fluctuation period shorter than one belt period.
There is a belt position control device disclosed in Japanese Patent Publication No. 21-210.
This belt position control device has a triangular mark formed continuously at the belt side end, and a sensor that generates a pulse having a waveform corresponding to the detected length of the triangular mark, and a reference position of the endless belt. The meandering of the belt is detected based on a comparison between a reference pulse corresponding to the detection length and a pulse to be measured.

[0011]

However, according to the conventional belt position control device, the meandering detection cycle of the belt is limited by the shape and interval of the mark, so that meandering repeated in a short cycle can be performed with high accuracy. Cannot be controlled at high speed. On the other hand, it is difficult to control high-accuracy and high-speed transport unevenness that is repeated in a short cycle for the same reason. Therefore, the object of the present invention is to detect the behavior of the belt with high accuracy at an arbitrary detection cycle, and meander the belt,
An object of the present invention is to provide a belt position or speed control device which is excellent in convergence of uneven transport.

[0012]

In order to achieve the above object, the present invention detects the position or speed of an endless belt that is stretched and rotated by a plurality of rolls including a drive roll at a predetermined detection cycle. Detecting means, storing means for storing the position or speed of the belt detected from a predetermined point on the belt by the detecting means before a predetermined rotation cycle of the belt, and detecting the position of the belt read from the storing means. Calculating means for calculating a difference position or speed by comparing the position or speed with the position or speed of the belt detected from the predetermined point by the detection means at a new rotation cycle; and calculating the difference position or difference speed. A correction unit that corrects with a correction coefficient prepared in advance and outputs corrected position data or corrected speed data; and Providing position or speed of the control device for a belt having a control unit for controlling the position or speed of the belt at the control cycle corresponding to the predetermined detection period of said detection means on the basis of the positive velocity data.

In the belt position or speed control device described above, the detecting means may detect the position or speed of the belt using a detection period set at a period shorter than a predetermined rotation period of the belt as a predetermined detection period. preferable. When the belt period is T and the behavior period of the belt is ΔT ₁ , the correction means corrects the respective amplitudes by multiplying the differential position or differential speed by 1 / (2SIN (πT / ΔT ₁ )) as a correction coefficient. ΠT / ΔT ₁ as a correction coefficient
It is preferable to calculate corrected position data or corrected speed data in which each phase is corrected by multiplying by −π / 2. The detecting means may be configured to detect the position or speed of the belt at one or more reference positions provided on the belt or at a position downstream of the reference position by a predetermined distance from the reference position. It may have two sensors, each sensor detecting the position in a different rotation cycle of the belt. Further, the detecting means may detect the position based on the detection of the side end of the belt or the detection of a mark continuously formed in a predetermined shape on the belt. The belt is a paper transport belt or an intermediate transfer belt of the image forming apparatus,
The mark may be formed by developing the electrostatic latent image with toner, and may be a toner image transferred to a paper transport belt or an intermediate transfer belt. The control means may be configured to control the attitude of the support shaft of the steering roll based on the corrected position data, or may be configured to control the rotation speed of the drive roll based on the corrected speed data. Further, the control means detects a phase at the time of sampling the position or speed of the belt detected by the detection means on the belt position fluctuation curve or the speed fluctuation curve, and from this phase, the period of the position fluctuation curve or the speed fluctuation curve It is preferable to control the position or speed of the belt at the same phase delayed by an integral multiple of the period.

Further, in order to achieve the above object, the present invention provides a detecting means for detecting a position or a speed of an endless belt which is stretched and rotated by a plurality of rolls including a driving roll at a predetermined detecting cycle, A correction amount for correcting an unsteady fluctuation component included in the position or speed of the belt is provided as a table, and a correction position or a correction speed of the belt from which the unsteady fluctuation component has been removed based on the correction amount. Correction means for outputting, and the position or speed detected by the detection means from a predetermined point on the belt before a predetermined rotation cycle of the belt as the corrected position or corrected speed corrected by the correction means. Storage means for storing a correction position or a correction speed;
The correction position or the correction speed of the belt read from the storage means is compared with the correction position or the correction speed of the belt detected from the predetermined point by the detection means at a new rotation cycle, and the difference position or the difference is calculated. Calculating means for calculating a speed; correcting means for correcting the differential position or the differential speed with a correction coefficient prepared in advance to output corrected position data or corrected speed data; and based on the corrected position data or corrected speed data. There is provided a belt position or speed control device having control means for controlling a position or a speed of the belt at a control cycle corresponding to the predetermined detection cycle of the detection means.

In the above-described belt position or speed control device, the detecting means may detect the position or speed of the belt using a detection period set at a period shorter than a predetermined rotation period of the belt as a predetermined detection period. preferable. When the belt period is T and the behavior period of the belt is ΔT ₁ , the correction means corrects the respective amplitudes by multiplying the differential position or differential speed by 1 / (2SIN (πT / ΔT ₁ )) as a correction coefficient. ΠT / ΔT ₁ as a correction coefficient
It is preferable to calculate corrected position data or corrected speed data in which each phase is corrected by multiplying by −π / 2. The detecting means may be configured to detect the position or speed of the belt at one or more reference positions provided on the belt or at a position downstream of the reference position by a predetermined distance from the reference position. It may have two sensors, each sensor detecting the position in a different rotation cycle of the belt. Further, the detecting means may detect the position based on the detection of the side end of the belt or the detection of a mark continuously formed in a predetermined shape on the belt. The belt is a paper transport belt or an intermediate transfer belt of the image forming apparatus,
The mark may be formed by developing the electrostatic latent image with toner, and may be a toner image transferred to a paper transport belt or an intermediate transfer belt. The control means may be configured to control the attitude of the support shaft of the steering roll based on the corrected position data, or may be configured to control the rotation speed of the drive roll based on the corrected speed data. Further, the control means detects a phase at the time of sampling the position or speed of the belt detected by the detection means on the belt position fluctuation curve or the speed fluctuation curve, and from this phase, the period of the position fluctuation curve or the speed fluctuation curve. It is preferable to control the position or speed of the belt at the same phase delayed by an integral multiple of the period.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for controlling the position or speed of a belt according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a tandem-type image forming apparatus applied in a first embodiment of the present invention, which is configured by arranging a plurality of photosensitive drums in parallel in the transport direction of a paper transport belt. I have. This image forming apparatus includes photosensitive drums 1K, 1Y, 1 provided for each color of K (black), Y (yellow), M (magenta), and C (cyan).
M and 1C, and the photosensitive drums 1K, 1Y, 1M and 1C
Chargers 2K, 2Y, 2 for applying a predetermined charge before the exposure of
M and 2C, and the photosensitive drums 1K, 1Y, 1M and 1C
Exposure units 3K, 3Y, 3M, and 3C that form an electrostatic latent image by exposing the photosensitive drum 1 with modulated light corresponding to image information;
Developing units 4K, 4Y, 4M and 4C for developing the electrostatic latent images formed on K, 1Y, 1M and 1C with toner, and a charging unit 5 arranged at a transfer position of the toner image and applying a predetermined charge
K, 5Y, 5M and 5C, and the photosensitive drums 1K, 1Y,
Cleaner 6 for removing toner remaining in 1M and 1C
K, 6Y, 6M and 6C, and the photosensitive drums 1K, 1Y,
Static eliminators 7K, 7Y, 7M and 7 for neutralizing 1M and 1C
C, a paper transport belt 9 stretched by a drive roll 8A, a driven roll 8B, and a steering roll 8C.
A registration roller 11 that feeds the recording paper supplied via the paper guide 10A to the paper guide 10B at a predetermined timing, a suction charger 12 provided at a supply point of the recording paper and applying a predetermined charge, A separation charger 13 for applying a predetermined charge necessary for separating the recording sheet onto which the toner image has been transferred, and a sheet guide 1 for fixing the toner image of the recording sheet supplied via a sheet guide 14A.
4B, a static eliminator 16 for removing electricity from the paper transport belt 9, a cleaner 17 for cleaning the surface of the paper transport belt 9, and a home position mark formed on the paper transport belt 9 to be described later. It has an optical sensor section 18, a belt position detection sensor 19 for detecting a side end of the sheet transport belt 9, and an arm 21 for steering the steering roll 8 C based on driving of the eccentric cam 20.

FIG. 2 shows a control device for controlling the position or speed of the belt according to the first embodiment. A drive motor 22 for driving the paper transport belt 9 and a side end of the paper transport belt 9 are arranged at a predetermined interval. A plurality of home position marks 9A to be formed, a light source 18A for irradiating measurement light to a passing position of the home position mark 9A, an optical system 18B for condensing light reflected by the paper transport belt 9, and an optical system 18B
An optical sensor 18C that receives the reflected light condensed via the optical sensor 18C and outputs a detection signal, a clock generation circuit 23 that generates a clock pulse of a predetermined period, and a detection signal of the optical sensor 18C that counts clock pulses. And a belt position detection sensor 19 that generates a trigger signal when a predetermined count value is reached from the timing at which the
A belt position detector 25 that detects the movement of the paper transport belt 9 in the width direction based on the detection signal, and outputs the detected position as belt position data; A switch circuit 26 for inputting the input signal to the control unit 27; an arithmetic processing unit 27 for performing predetermined arithmetic processing based on the belt position data at the same position of the paper transport belt 9; An eccentric cam drive circuit 29 for generating a drive voltage for the eccentric cam 20 based on the output of the eccentric cam 20 is provided.

The home position mark 9A is formed by forming an electrostatic latent image corresponding to the mark shape on one of the photosensitive drums 1K, 1Y, 1M and 1C, developing the toner, and transferring the latent image to the paper transport belt 9. The marks are arranged at equal intervals so that the interval between the marks is 1 / integer with respect to one cycle of the paper transport belt 9. In FIG. 2, the transport direction of the paper transport belt 9 is the X direction,
0, the displacement direction of the steering roll 8C is the Y direction,
The displacement direction of the paper transport belt 9 based on the displacement of the steering roll 8C is defined as the Z direction.

FIG. 3 shows the arithmetic circuit 27, and the arithmetic circuit 2
7, a data storage unit 30 for storing belt position data input from the switch circuit 26; a first storage unit 31 and a second storage unit 32 for storing belt position data input from the data storage unit 30; 30 and a comparison unit 33 that calculates the belt position data input from the second storage unit 32 and outputs the result as difference data.

The operation of the belt position or speed control device of the present invention will be described below with reference to the flowchart shown in FIG.

First, the cycle of the paper transport belt 9 and the meandering cycle of the paper transport belt 9 are stored in a memory (not shown). As the meandering cycle of the paper transport belt 9, data measured in advance for a belt system for performing meandering control can be used (step 1).

Next, when the drive motor 22 is driven to convey the sheet conveying belt 9 in the direction of the arrow, the optical sensor 18
Each time C detects a plurality of home position marks 9A formed on the surface of the sheet conveying belt 9, an electric signal is input to the counter 24. The counter 24 counts a clock pulse input from the clock generation circuit 23 when an electric signal is input, and outputs a trigger signal to the switch circuit 26 when a predetermined count value is reached.

The switch circuit 26 receives belt position data corresponding to the position of the side end of the sheet conveying belt 9 from the belt position detecting unit 25. The belt circuit for one revolution of the belt is input at the timing when the trigger signal is input. The position data is output to the arithmetic circuit 27. By doing so, it is possible to collect the belt position data a plurality of times according to the count value set between the detection of the first home position mark and the detection of the second home position mark. Will be possible. The belt position data of the first rotation input to the arithmetic circuit 27 is stored in the second storage unit 32 via the data storage unit 30 and the first storage unit 31 (Step 2).

Next, based on the operation in step 2 described above, the belt position data for the second cycle is input to the arithmetic circuit 27. The belt position data of the second cycle is transferred to the first storage unit 31 and the comparison unit 33 via the data storage unit 30. At the same time, the belt position data of the first rotation is read from the second storage unit 32 and transferred to the comparison unit 33. Thereafter, the belt position data of the second rotation is transferred from the first storage unit 31 to the second storage unit 32 (step 3).

The comparison unit 33 determines that the 1
The difference between the belt position data in the second lap and the belt position data in the second lap is calculated, and the calculation result is used as difference data as a correction circuit 28.
Output to (Step 4).

In the above-described belt unit, the belt cycle does not always coincide with the belt meandering cycle. Therefore, even if the difference data is calculated based on the belt position data at the same point of the belt, the calculation result indicates the amplitude and phase. A gap may occur. The correction circuit 28 corrects the deviation of the amplitude and phase of the difference data and outputs the result as meandering data.

The preconditions for correcting the difference data are that the belt position data is detected at the same point of the belt, the period (T) of _one rotation of the belt and the meandering period (ΔT ₁ ) of the belt are known, Assuming that the meandering cycle generated in the conveying belt 9 is one type and the meandering amplitude is constant, the belt position data of the first rotation of the paper conveying belt 9 is F ₁ (t) = B _AMP · SIN (ω ₀ t + φ) + W _AMP · SIN (ω ₁ t + φ ₁ ) --- (1) * ω = 2π / T, ω ₁ = 2π / ΔT ₁ The belt position data of the second round of the paper transport belt 9 is F ₂ (t) = B _AMP · SIN (ω ₀ (t + T) + φ) + W _AMP · SIN (ω ₁ (t + T) + φ ₁ ) −−− (2) When the difference of the belt position data is calculated, ΔF (t) = F ₂ (t) −F ₁ (t) = B _AMP · SIN (ω ₀ (t + T) + φ) + W _AMP · SIN (ω ₁ (t + T) + φ ₁ ) −B _AMP · SIN (ω ₀ t + φ) − W _AMP · SIN (ω ₁ t + φ ₁ ) = W _AMP · SIN (ω ₁ (t + T) + φ ₁ ) −W _AMP · SIN (ω ₁ t + φ ₁ ) ∵B _AMP · SIN (ω ₀ (t + T) + φ) = B _AMP · SIN (ω ₀ t + φ) − −− (3) Rearranging equation (3), ΔF (t) = 2W _AMP · COS (ω ₁ t + φ ₁ + ω ₁ · T / 2) · SIN (ω ₁ · T / 2) −−− (4) Equation (4) is a waveform that appears as actual difference data, and has a difference in amplitude and phase. Therefore, to correct the amplitude, A '= W _AMP / (2 W _AMP SIN (ω ₁ T / 2)) = 1 / (2 SIN (ω ₁ T / 2)) --- (5) = 1 / ( 2SIN (πT / ΔT ₁ )) −−− (5 ′) To correct the phase, COS (ω ₁ t + φ ₁ + ω ₁ · T / 2) = SIN (ω ₁ t + φ ₁ + ω ₁ · T / 2−π / 2) Ph ′ = (ω ₁ t + φ ₁ + ω ₁₎・ T / 2-π / 2)-(ω ₁ t + φ ₁ ) = ω ₁・ T / 2-π / 2 --- (6) = πT / ΔT ₁ -π / 2 --- (6 ') Find the correction coefficient. Thus, the meandering data is expressed as W _AMP · SIN (ω ₁ t + φ ₁ ) = A ′ · ΔF (t−Ph ′) (7) (Step 5)

Since the amplitude A 'and the phase Ph' are known from preconditions, meandering data is calculated by performing amplitude and phase correction on the difference data ΔF (t). The correction circuit 28 based on the meandering data corrected in this way
When an electric signal is output to the eccentric cam drive circuit 29 at a predetermined timing, and a drive current corresponding to the steering amount of the steering roll 8C is supplied to a drive motor (not shown) of the eccentric cam 20, the eccentric cam 20 It rotates to displace the steering roll 8C in the YY ′ direction. The meandering is converged by displacing the sheet conveying belt 9 in the Z direction based on the displacement of the steering roll 8C (step 6).

As described above, the belt position data corresponding to the movement of the belt-side end is input, and the eccentric cam 2 is formed based on the meandering data obtained by correcting the difference data from the belt position data of the front circumference.
By driving 0, belt meandering control can be performed in a cycle shorter than one rotation of the belt. In the above embodiment, since the belt position data is input to the arithmetic circuit 27 based on the trigger signal input from the counter 24, the belt meandering control per unit time can be performed by changing the trigger signal generation interval. The number of times can be set arbitrarily.

FIG. 5 shows another configuration of the arithmetic circuit. The arithmetic circuit 34 includes a shift register 35 to which the belt position data is input from the switch circuit 26, and a shift register 35.
And a comparison unit 36 to which belt position data is input from the switch circuit 26. The shift register 35 delays the input belt position data by one rotation of the belt,
6, the comparison unit 36 outputs the Nth (N is an integer) belt position data input from the switch circuit 26 and the (N−1) th belt input from the shift register 35. The configuration may be such that the difference from the belt position data is calculated.

FIG. 6 shows another configuration of the sheet conveying belt. Instead of forming a belt position detecting mark 37 having a predetermined width in the conveying direction along the belt side end, instead of detecting the belt side end, FIG. The same position of the belt position detection mark 37 may be detected by the belt position detection sensor 19.

FIGS. 7 to 12 show the relationship between the belt cycle and the belt meandering cycle in the above-described belt unit.
(A) is belt position data by the belt position detection sensor 9, (b) is difference data based on the belt position data,
(C) shows the meandering belt actually generated on the paper transport belt 9, and (d) shows meandering data after the difference data correction.
The belt cycle is 0.15 Hz.

FIG. 7 shows that the belt meandering cycle is 1.20 Hz.
Since the belt meandering cycle is an integral multiple of the belt cycle, the difference between the belt position data is calculated to be zero as shown in FIG. 7B. For this reason, when the amplitude and phase are corrected, a belt meander (FIG.
Unlike (c)), meandering data cannot be obtained. Further, the belt cycle shown in FIG.
z, even when the belt meandering cycle is 1.35 Hz, since the belt meandering cycle is an integral multiple of the belt cycle, the difference between the belt position data becomes zero.

FIG. 8 shows that the belt meandering cycle is 1.23H.
FIG. 9 shows that the belt meandering cycle is 1.26 Hz and FIG.
Shows a case where the belt meandering cycle is 1.29 Hz, and FIG. 11 shows a case where the belt meandering cycle is 1.32 Hz. The difference data obtained by calculating the difference between the belt position data is different from the belt meandering actually occurring. Therefore, the meandering data can be obtained by correcting the amplitude and the phase based on the above-described equations (5 ′) and (6 ′).

FIG. 13 shows a second embodiment of the present invention, which has two belt position detection sensors 19A and 19B for detecting a belt position detection mark 37, and
When C detects the home position mark 9A, the belt position detection sensor 19A detects the belt position detection mark 37, and thereafter, the belt position detection sensor 19B detects the belt position detection mark 37 at the same point.

FIG. 14 shows the detection time lag when the same point of the paper transport belt 9 is detected by the two belt position detection sensors 19A and 19B. □ ◇ ▽ ◎). Since the belt position detection sensors 19A and 19B are arranged at intervals, a time difference t occurs when trying to detect the same point (for example, a mark ○) on the paper transport belt 9.

Accordingly, the belt position data detected by the belt position detection sensor 19B and the belt position detection sensor 19A
By calculating the difference between the belt position data detected in step (1), even if the belt meandering cycle is an integral multiple of the belt cycle, the belt cycle T can be calculated as ΔT 'shifted by the time difference t, so that difference data is obtained. Can be. If the belt meandering cycle is not an integral multiple of the belt cycle, one of the belt position detection sensors 19A and 19B may be used.

FIG. 15 shows the position fluctuation of the belt side end based on the belt meandering control. When the meandering control is performed using the difference data, as shown in FIG.
Toward 00s, the meandering belt converges,
After 50 s, it diverges again and becomes uncontrollable. On the other hand, when meandering control is performed using meandering data obtained by correcting the amplitude and phase based on the above-described equations (5 ′) and (6 ′) for the difference data, FIG. As shown in the figure, the belt meander is quickly converged.

FIG. 16 shows a third embodiment of the present invention, which is configured to control the transport unevenness of the paper transport belt 9. Since the configuration of each unit is the same as that of the first embodiment, a duplicate description will be omitted.

The optical sensor 18C detects a plurality of home position marks 9A formed at predetermined intervals on the paper transport belt 9 and outputs an electric signal to the counter 24. The counter 24 counts a clock pulse input from the clock generation circuit 23 based on the input of the electric signal until the next electric signal input timing, and outputs a count value to the arithmetic circuit 27. In this way, the uneven transport data for one round of the belt is input to the arithmetic circuit 27.

The arithmetic circuit 27 calculates the difference at the same point between the transport unevenness data on the Nth round (N is an integer) and the transport unevenness data on the (N-1) th round. By this calculation, difference data from which the mark interval variation has been removed is obtained. Since the uneven transport is not always generated in synchronization with the belt cycle similarly to the meandering of the belt, the difference data is input to the correction circuit 28 and the correction is performed based on the above-described equations (5 ′) and (6 ′). As a result, uneven transport data can be obtained.

An electric signal is output from the correction circuit 28 to the motor drive circuit 38 at a predetermined timing based on the uneven transport data corrected in this manner, and a drive current corresponding to the uneven gain correction gain is supplied to the drive motor 22. The transport speed of the paper transport belt 9 is controlled by being supplied.

When the image unevenness is corrected by applying the above-mentioned uneven transport data to the image forming apparatus, the image shift in the transport direction calculated by the arithmetic circuit 28 and the image shift in the direction perpendicular to the transport direction are performed. The image position shift can be controlled by correcting the writing timing of the exposure unit with respect to the image position shift.

FIG. 17A shows a configuration for removing an unsteady fluctuation component generated in the paper transport belt 9. The memory 39 stores the data of the unsteady fluctuation component, and the memory 39 stores the data of the unsteady fluctuation component. Is added to the belt position data. Hereinafter, a case where the timing at which the unsteady fluctuation occurs is known will be described.

As shown in FIG. 17B, the memory 39 stores the unsteady fluctuation component generated in the target belt system at the time Tm (Tm time) during the generation from the generation timing. The average data obtained by adding all the M pieces of data and dividing by M is stored as a table, and the addition circuit 40 calculates the non-stationary fluctuation component stored in the memory 39 at the timing when the non-stationary fluctuation occurs. Is added to the belt position data and corrected.

FIG. 18A shows a configuration using a repetitive control system, in which the detection data correction unit 41 detects fluctuations in belt meandering or uneven transport caused by disturbance applied to the paper transport belt 9. When the correction and the feedback control are performed, the control timing is optimally set by using the deviation one cycle before the periodic fluctuation. In the drawing, f ₁ ... _L−1 are gain coefficients specific to repetitive control, and fx is a feedback gain used for an optimal regulator or the like. z is an operator of the z-transform used in the discrete-time function, and z ^-1 represents one sampling delay.

For example, when performing belt meandering control, FIG.
As shown in FIG. 8B, when the timing at which the difference between the belt position data is calculated is A, there is a time difference between the timing and the control timing B after the calculation process is performed, so that even if the steering roll is steered, the belt becomes A situation where the meandering does not converge occurs. In order to prevent such a situation, by delaying the control start to dimension C having the same phase as timing A, it is possible to perform appropriate belt meandering control on the calculation result.

In the above-described embodiment, the paper transport belt has been described. However, a similar configuration can be used for a belt member such as an intermediate transfer belt and a paper transport device. The belt meandering control mechanism is not limited to the steering roll, and may be any configuration that can control the movement of the belt member in a direction perpendicular to the transport direction.

[0050]

As described above, according to the belt position or speed control apparatus of the present invention, the data of the belt position or speed detected before the predetermined rotation period of the paper transport belt and the data of the belt position or speed are detected at the new rotation period. The difference between the data of the belt position or the speed at the same point and the data of the corrected position or speed corrected by the correction coefficient is calculated. And the convergence of belt meandering and transport unevenness can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a tandem type image forming apparatus applied in a first embodiment.

FIG. 2 is an explanatory diagram illustrating a control device for controlling the position or speed of a belt according to the first embodiment.

FIG. 3 is an explanatory diagram illustrating an arithmetic circuit 27 according to the first embodiment.

FIG. 4 is a flowchart of a belt position or speed control device according to the first embodiment.

FIG. 5 is an explanatory diagram showing an arithmetic circuit 34;

FIG. 6 is an explanatory diagram showing another configuration of the sheet transport belt 9;

FIG. 7 is an explanatory diagram showing a relationship between a belt cycle and a belt meandering cycle in the first embodiment.

FIG. 8 is an explanatory diagram illustrating a relationship between a belt cycle and a belt meandering cycle in the first embodiment.

FIG. 9 is an explanatory diagram showing a relationship between a belt cycle and a belt meandering cycle in the first embodiment.

FIG. 10 is an explanatory diagram showing a relationship between a belt cycle and a belt meandering cycle in the first embodiment.

FIG. 11 is an explanatory diagram illustrating a relationship between a belt cycle and a belt meandering cycle in the first embodiment.

FIG. 12 is an explanatory diagram illustrating a relationship between a belt cycle and a belt meandering cycle in the first embodiment.

FIG. 13 is an explanatory diagram showing a control device for controlling the position or speed of the belt according to the second embodiment.

FIG. 14 is an explanatory diagram illustrating a control device for controlling the position or speed of a belt according to the second embodiment.

FIG. 15A shows a belt position when belt meandering control is performed based on difference data, and FIG. 15B shows a belt position when belt meandering control is performed based on meandering data.

FIG. 16 is an explanatory diagram illustrating a control device for controlling the position or speed of a belt according to a third embodiment.

17A shows a configuration for removing an unsteady fluctuation component generated in the paper transport belt 9, and FIG. 17B shows average data of the unsteady fluctuation component stored in the memory 39. FIG.

FIG. 18A shows a repetitive control system, and FIG.
Indicates a control timing based on the repetitive control.

[Explanation of symbols]

 1K, 1Y, 1M, 1C, photosensitive drums 2K, 2Y, 2M, 2C, chargers 3K, 3Y, 3M, 3C, exposure units 4K, 4Y, 4M, 4C, developing units 5K, 5Y, 5M, 5C, charging 6K, 6Y, 6M, 6C, cleaner 7K, 7Y, 7M, 7C, static eliminator 8A, drive roll 8B, driven roll 8C, steering roll 9, paper transport belt 10A, paper guide 10B, paper guide 11, registration roller 12 , Adsorption charger 13, separation charger 14 A, paper guide 14 B, paper guide 15, fixing device 16, static eliminator 17, cleaner 18, optical sensor 18 19, belt position detection sensor 20, eccentric cam 21, arm 22 , Drive motor 23, clock generation circuit 24, counter 25, belt position detector 26, switch circuit 27, arithmetic circuit 28 , Correction circuit 29, eccentric cam drive circuit 30, main storage unit 31, first storage unit 32, second storage unit 33, comparison unit 34, arithmetic circuit 35, shift register 36, comparison unit 37, belt position detection mark 38, Motor drive circuit 39, memory 40, adder circuit 41, detection data correction unit

Claims (20)

[Claims] 1. A detecting means for detecting a position or a speed of an endless belt which is stretched and rotated by a plurality of rolls including a driving roll at a predetermined detecting cycle, and wherein the detecting means determines a predetermined rotating cycle of the belt. Storage means for storing the position or speed of the belt detected from a predetermined point on the belt before; position or speed of the belt read from the storage means; and Calculating means for comparing the position or speed of the belt detected from a predetermined point to calculate a difference position or speed; and correcting the difference position or speed by a correction coefficient prepared in advance. Correction means for outputting speed data; and the position or the position of the belt based on the corrected position data or the corrected speed data. Position or speed of the control device for a belt, characterized in that it comprises a control means for controlling the degree in control cycle corresponding to the predetermined detection period of said detection means. 2. The apparatus according to claim 1, wherein said detecting means detects a position or a speed of said belt using a detection cycle set at a cycle shorter than said predetermined rotation cycle of said belt as said predetermined detection cycle. A belt position or speed control device as described. 3. When the belt cycle is T and the behavior cycle of the belt is ΔT ₁ , the correction means adds 1 / (2 SIN (πT
/ ΔT ₁ )) to correct each amplitude, and
2. The belt position or speed control according to claim 1, wherein the correction position data or the corrected speed data is calculated by multiplying πT / ΔT ₁ −π / 2 as the correction coefficient to correct the respective phases. apparatus. 4. The apparatus according to claim 1, wherein the detecting means detects the position or speed of the belt at one or more reference positions provided on the belt or at a position downstream of the reference position by a predetermined distance. 2. A control device for controlling the position or speed of a belt according to claim 1. 5. The belt according to claim 1, wherein said detecting means has at least two sensors in a conveying direction of said belt, each of said sensors detecting said position at a different rotation period of said belt. Position or speed control device. 6. The apparatus according to claim 1, wherein said detecting means detects said position based on detection of a side end of said belt or detection of a mark continuously formed in a predetermined shape on said belt. A control device for controlling the position or speed of the belt according to claim 1. 7. The belt is a paper transport belt or an intermediate transfer belt of an image forming apparatus. The mark is formed by developing an electrostatic latent image with toner, and is transferred to the paper transport belt or the intermediate transfer belt. 7. The apparatus according to claim 6, wherein the toner image is a toner image to be formed. 8. The belt position or speed control device according to claim 1, wherein said control means controls a posture of a support shaft of a steering roll based on said corrected position data. 9. The belt position or speed control device according to claim 1, wherein said control means controls the rotation speed of said drive roll based on said corrected speed data. 10. The control means detects a phase at the time of sampling the position or speed of the belt detected by the detection means on a position change curve or a speed change curve of the belt, and detects the position based on the phase. 2. The belt position or speed control device according to claim 1, wherein the belt position or speed is controlled with the same phase delayed by an integral multiple of the period of the fluctuation curve or the speed fluctuation curve. 11. A detecting means for detecting the position or speed of an endless belt that is stretched and rotated by a plurality of rolls including a driving roll at a predetermined detection cycle, and an unsteady state included in the position or speed of the belt. Correction means for correcting a variable component as a table, and outputting a correction position or a correction speed of the belt from which the unsteady variable component has been removed based on the correction amount; and Storage means for storing the position or speed detected from a predetermined point on the belt before a predetermined rotation cycle of the belt as the corrected position or speed corrected by the correction means; read from the storage means A correction position or a correction speed of the belt, and the position or the speed detected by the detection means from the predetermined point in a new rotation cycle. Calculating means for calculating a difference position or a difference speed by comparing a correction position or a correction speed of the belt whose degree has been corrected by the correction means; and correcting the difference position or the difference speed by a correction coefficient prepared in advance. Correction means for outputting correction position data or correction speed data; and control for controlling the position or speed of the belt at a control cycle corresponding to the predetermined detection cycle of the detection means based on the correction position data or correction speed data. Means for controlling the position or speed of the belt. 12. The apparatus according to claim 11, wherein said detection means detects a position or a speed of said belt by using a detection cycle set at a cycle shorter than said predetermined rotation cycle of said belt as said predetermined detection cycle. A belt position or speed control device as described. 13. The correction means according to claim 1, wherein the belt cycle is T,
ΔT ₁ When there is the difference position
Or 1 / (2 SIN (π
T / ΔT₁ )) To correct each amplitude,
ΠT / ΔT as the correction coefficient₁ Multiply by -π / 2
The corrected position data or
12. A structure for calculating the correction speed data.
A belt position or speed control device as described. 14. The apparatus according to claim 1, wherein said detecting means detects the position or speed of said belt at one or more reference positions provided on said belt or at a position downstream of said reference position by a predetermined distance. 12. A control device for controlling the position or speed of a belt according to claim 11. 15. The belt according to claim 11, wherein said detecting means has at least two sensors in a conveying direction of said belt, and each sensor detects said position at a different rotation period of said belt. Position or speed control device. 16. The apparatus according to claim 1, wherein said detecting means detects the position based on detection of a side end of the belt or detection of a mark continuously formed in a predetermined shape on the belt. 12. A control device for controlling the position or speed of a belt according to claim 11. 17. The paper transfer belt or an intermediate transfer belt of an image forming apparatus, wherein the mark is formed by developing an electrostatic latent image with toner and transferred to the paper transfer belt or the intermediate transfer belt. 17. The control device for controlling the position or speed of a belt according to claim 16, wherein the toner image is a toner image to be formed. 18. The belt position or speed control device according to claim 11, wherein said control means controls a posture of a support shaft of a steering roll based on said corrected position data. 19. The apparatus according to claim 11, wherein said control means controls a rotation speed of said drive roll based on said corrected speed data. 20. The control means detects a phase at the time of sampling the position or speed of the belt detected by the detection means on a position change curve or a speed change curve of the belt, and detects the position from the phase. 12. The belt position or speed control device according to claim 11, wherein the position or speed of the belt is controlled at the same phase delayed by an integral multiple of the period of the fluctuation curve or the speed fluctuation curve.