JP2000162846A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the scale of a circuit or volume of a program for calculating the compensation value for motor smaller and to decrease color deviations due to unevenness in the rotation of a photoreceptor drum or a carrying belt drive roll, etc., by controlling the frequency of a drive signal set to each image carrier drive source, based on the deviation of frequency of a first pulse signal. SOLUTION: In this image-forming device, each image carriers (photoreceptor drums) 1a to 1d are each driven to be rotated by each image carrier drive source (stepping motor) 8, based on the frequency of the drive signals (stepping motor drive pulse, FG pulse) which are set independently. The first pulse signals (encoder pulses), which are frequencies that are integral multiples of each drive signal set at the stepping motors 8 are independently generated, according to the rotation of each image carrier 1a-1d by a multiple number of image carrier rotation state detecting means (encoder) 10. Then, the frequencies of drive signals set at the stepping motor 8 are independently controlled, based on the deviations in frequencies of the first pulse signals generated by the encoders 10 for each image carrier rotation control means 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus comprising a plurality of image forming units provided for each color component, forming a color component image on a plurality of image carriers, respectively. The present invention relates to an image forming apparatus capable of forming a multicolor image by superimposing and transferring a color component image onto a recording medium conveyed by an endless belt-like moving body sequentially passing through each of the image carriers.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic color image forming apparatus has a plurality of image forming sections for speeding up, and sequentially transfers images of different colors onto a recording material held on a conveyor belt. Various methods have been proposed.

A problem with an image forming apparatus having a plurality of image forming units is as follows:
The unevenness of the movement of a plurality of photosensitive drums and the conveyor belt, the relationship between the outer peripheral surface of the photosensitive drum at the transfer position of each image forming unit and the movement amount of the conveyor belt, and the like occur separately for each color, and the color images are superimposed. Sometimes, the colors do not match, and color shift (position shift) occurs.

The color misregistration includes a main scanning direction and a sub-scanning (transport) direction, and includes a stationary error in which the amount of deviation is constant in a sheet and an unsteady error in which the amount of deviation varies periodically. is there.

The color misregistration in the main scanning direction includes a left end writing position error, a main scanning width error, and the like. The color misregistration in the sub-scanning direction includes a leading end writing position error. Further, as the unsteady color shift in the sub-scanning direction, there is a color shift caused by uneven conveyance. Regarding the steady color misregistration, a color misregistration detection pattern was formed for each color on the conveyor belt, and detected by a pair of optical sensors provided on both sides of the downstream portion of the conveyor belt. In some cases, various adjustments are made in accordance with the amount of deviation.

[0006] Further, with respect to irregular color shifts, particularly those caused by uneven transport, there is a monitor that monitors the rotation state of the photosensitive drum or the transport belt and controls a drive source such as a motor so as to be constant. . Hereinafter, the example will be described.

An encoder is provided on the rotating shaft of the photosensitive drum which is rotationally driven by transmitting the rotational drive of the stepping motor by a reduction gear, detects the rotational state of the photosensitive drum, and calculates the error of the photosensitive drum with respect to the theoretical value. Calculate. If necessary, high-frequency components caused by the tooth pitch of the reduction gear are removed by a filter process (LPF: low-pass filter) or the like, and then the above-described error of the photosensitive drum is canceled (from this error of the photosensitive drum, A motor correction value for canceling the minute is calculated, and the rotation of the stepping motor is controlled (according to the motor correction value).

[0008] Here, the stepping motor is rotated "20"
Assuming that the stepping motor is a “0” step, the deceleration by the reduction gear is “1/12”, and the number of encoder pulses output in one rotation of the photosensitive drum 1 is “1000”,
The “1” pulse of the encoder corresponds to the “2.4 (2400/1000)” step of the stepping motor. Therefore, the output frequency of the encoder and the drive frequency of the stepping motor are “2.4: 1”.

Referring to FIG. 11, the relationship between an error of an encoder pulse which is a rotation state detection signal of a photosensitive drum of a conventional image forming apparatus and a correction value of a stepping motor cycle will be described.

FIG. 11 is a diagram showing a relationship between an error of an encoder pulse which is a rotation state detection signal of a photosensitive drum of a conventional image forming apparatus and a correction value of a stepping motor cycle.

In the figure, E1 to E6 are encoder pulse Nos. ΔE1 to ΔE6 are errors of the encoder pulse period after the LPF (after the LPF), and the encoder pulse N
o. This corresponds to E1 to E6. M1 to M13 are motor step numbers. ΔM1 to ΔM13 are motor correction values, and the motor step No. It corresponds to M1 to M13. Here, a is a coefficient, which is a correction coefficient for calculating the motor correction value ΔM based on the error ΔE of the encoder pulse period.

The operation of calculating the motor correction value .DELTA.M based on the error (after LPF) .DELTA.E of the conventional encoder pulse period will be described below.

Since the output frequency of the encoder and the drive frequency of the stepping motor are “2.4: 1 (12: 5)”, first, the encoder pulse No. The error (after LPF) of 1 (the first pulse of the encoder) ΔE1 is calculated as “ΔE1 × 5 /
12 ”,“ ΔE1 × 5/12 ”,“ ΔE1 × 2/12 ”
And the error of encoder pulse No1 "ΔE1 ×
5/12 "and" ΔE1 × 5/12 ". The motor correction value “Δ” for M1 (first motor step)
M1 = a × ΔE1 × 5/12 ”and the motor step No.
The motor correction value “ΔM2 =
a × ΔE1 × 5/12 ”is calculated.

Next, the encoder pulse No. 2 (after LPF) ΔE2 is “ΔE2 × 3/12”, “ΔE2
× 5/12 ”and“ ΔE2 × 4/12 ”. 1 error “ΔE1 × 2/12” and the encoder pulse No. 2 error “ΔE2 × 3/12”
From the motor step No. M3 (3rd motor step)
Motor correction value “ΔM3 = a × (ΔE1 × 2/12 + Δ
E2 × 3/12) ”and calculate the encoder pulse No.
Motor step N from the error “ΔE2 × 5/12”
o. The motor correction value “ΔM
4 = a × ΔE2 × 5/12 ”is calculated.

Further, the encoder pulse No. 3 (after LPF) ΔE3 is calculated as “ΔE3 × 1/12” and “ΔE3
3 × 5/12 ”,“ ΔE3 × 5/12 ”,“ ΔE3 × 1
/ 12 "and the encoder pulse No. 2 error [ΔE3 × 4/12] and encoder pulse No. 3 from the error “ΔE3 × 1/12” of the motor step No. 3 M
5 (3rd motor step) motor correction value “ΔM5 = a
× (ΔE2 × 4/12 + ΔE3 × 1/12) ”.

Thereafter, the same operation is repeated to repeat the encoder pulse no. 5 (encoder 5th pulse) to motor step N
o. The same operation is repeated for M12 (12th motor step).

[0017]

However, the conventional image forming apparatus has the following disadvantages.

As described above, the motor step No.
The calculation of the motor correction value (ΔM) corresponding to (M) is a product-sum calculation of a plurality of encoder errors and coefficients using the encoder error (ΔE) as a variable, including filtering.

This is because the ratio of the frequency for detecting the rotation state of the photosensitive drum or the conveyor belt driving roller to the control frequency of the motor as the driving source has a fraction (not an integral multiple). This is because the coefficient used for calculating the motor correction value differs depending on (M).

As described above, in the conventional image forming apparatus, there are five types (“5/12”, “2/12” and “3/12”, “4/12” and “1/12”) depending on the difference in coefficient. , "1/1
2 "and" 4/12 ", and" 3/12 "and" 2/12 ").

The processing of these arithmetic expressions is performed by hardware (H /
W), there is a problem in that the circuit scale increases, and when it is realized by software (S / W), the amount of programs increases, the processing speed decreases, and the throughput decreases. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the first to eleventh inventions according to the present invention is that each photosensitive drum is rotated in accordance with the rotation of each photosensitive drum. By controlling the frequency of the drive signal set for the motor for driving each photosensitive drum based on the frequency error of the output pulse of the encoder that generates a pulse signal having an integer multiple of the drive signal frequency of the motor for driving the respective photosensitive drums In addition, a motor correction value for correcting rotation unevenness of a photosensitive drum or the like can be calculated by a single product-sum operation, thereby reducing a circuit scale and a program amount.
It is an object of the present invention to provide an image forming apparatus capable of efficiently reducing a color shift caused by uneven conveyance of a recording medium.

[0023]

According to a first aspect of the present invention, a plurality of image forming units (laser scanners 2a to 2d shown in FIG. 1) provided for each color component are provided with a plurality of image carriers (FIG. 1). 1
An endless belt-like moving body (FIG. 1) forms color component images on the photosensitive drums 1a to 1d) and passes the color component images formed on the image carriers sequentially through the image carriers. In the image forming apparatus capable of forming a multi-color image by superimposing and transferring the image on a recording medium conveyed by the conveying belt 3), the frequency of the drive signal (stepping motor driving pulse, FG pulse) set individually is determined. A plurality of image carrier driving sources (stepping motor 8 shown in FIG. 2 and D
C brushless motor 1008) and a first pulse signal (frequency) that is an integral multiple of the frequency of each drive signal individually set for each image carrier drive source in accordance with the rotation of each image carrier. A plurality of image carrier rotation state detecting means (encoders 10 shown in FIGS. 2 and 8) for respectively generating encoder pulses), and a frequency error of a first pulse signal generated by each image carrier rotation state detecting means (FIG. (Calculated by the pulse rate correction calculation unit 305 shown in FIGS. 5 and 9) based on the calculation by the encoder cycle error calculation unit 302 shown in FIGS. It has a plurality of image carrier rotation control means (control means 11 shown in FIG. 2 and control means 1011 shown in FIG. 8) for respectively controlling the frequency of the drive signal.

According to a second aspect of the present invention, the frequency of a set drive signal (stepping motor drive pulse, FG
A driving roller driving source (stepping motor 8 shown in FIG. 2, FIG. 2) for driving the endless belt-shaped moving body via a predetermined driving roller (driving roller 4) on which the endless belt-shaped moving body is suspended based on the pulse). And a driving roller that generates a second pulse signal having a frequency that is an integral multiple of the frequency of the driving signal set in the driving roller driving source in accordance with the rotation of the driving roller. Rotation state detection means (encoder 1 shown in FIGS. 2 and 8)
0) and the frequency error of the second pulse signal generated by the drive roller rotation state detection means (calculated by the encoder cycle error calculation unit 302 shown in FIGS. 5 and 9). The second control means (control means 11 shown in FIG. 2,
And control means 1011) shown in FIG.

According to a third aspect of the present invention, each of the image carriers is formed in a drum shape (photosensitive drum 1a shown in FIG. 1).
1d), each of the image carrier rotation state detection means is a rotary encoder (encoder 10 shown in FIGS. 2 and 8) provided on an extension of the drum shaft, and each of the image carrier rotation state detection means is The frequency of the generated first pulse signal is the output frequency of each rotary encoder.

According to a fourth aspect of the present invention, each of the image carriers is formed in an endless belt shape (a belt-shaped photoconductor not shown), and each of the image carrier driving sources is formed in an endless belt shape. The image carriers are respectively driven via predetermined drive rollers (drive rollers (not shown)) on which the respective image carriers are suspended. A rotary encoder (encoder 10 shown in FIGS. 2 and 8) provided on an extension line of the first embodiment, wherein the frequency of the first pulse signal generated by each of the image carrier rotation state detecting means is equal to the output frequency of each rotary encoder. What you do.

According to a fifth aspect of the present invention, the driving roller rotation state detecting means is a rotary encoder (encoder 10 shown in FIGS. 2 and 8) provided on an extension of the driving roller shaft. The frequency of the second pulse signal generated by the roller rotation state detecting means is used as the output frequency of the rotary encoder.

According to a sixth aspect of the present invention, each of the image carrier driving sources is a stepping motor (stepping motor 8 shown in FIG. 2), and a driving signal of each of the image carrier driving sources is set. The frequency is a drive pulse frequency of the stepping motor.

In a seventh aspect according to the present invention, each of the image carrier driving sources includes a third one corresponding to a rotation state of each image carrier driving source.
DC brushless motor (DC brushless motor 1008 shown in FIG. 8) for generating the pulse signal (FG signal) of FIG. 8, and the frequency of the driving signal set for each image carrier driving source is the frequency of the third pulse signal. It is assumed that.

According to an eighth aspect of the present invention, the driving roller driving source is a stepping motor (stepping motor 8 shown in FIG. 2), and the frequency of the driving signal set in the driving roller driving source is stepping motor. The drive pulse frequency of the motor is used.

According to a ninth aspect of the present invention, the driving roller driving source is a third driving device according to a rotation state of each image carrier driving source.
DC brushless motor (DC brushless motor 1008 shown in FIG. 8) that generates the pulse signal (FG signal) of FIG. 8, and the frequency of the drive signal set in the drive roller drive source is the frequency of the third pulse signal. Things.

According to a tenth aspect of the present invention, in each of the image carrier rotation state detecting means, each drive individually set to each of the image carrier drive sources in accordance with the rotation of each image carrier. A first pulse signal having a frequency that is a power-of-two multiplication ratio (an integral power-of-two multiplication ratio) of the frequency of the signal is generated.

According to an eleventh aspect of the present invention, the driving roller rotation state detecting means includes:
A second pulse signal having a frequency which is a power-of-two ratio (an integral power-of-two ratio) of the frequency of the drive signal set in the drive roller drive source.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on the illustrated embodiment.

[First Embodiment] FIG. 1 is a cross-sectional view illustrating the overall structure of an image forming apparatus according to a first embodiment of the present invention. In particular, FIG. 1 shows four colors, namely, yellow (Y) and magenta (M). ), Cyan (C), and black (Bk).

In the figure, 1a is a photosensitive drum for black (Bk), 1b is a photosensitive drum for cyan (C), 1c
Is a photosensitive drum for magenta (M), and 1d is a photosensitive drum for yellow (Y), and forms an electrostatic latent image of each color.
Each of the photosensitive drums 1a to 1d is connected to a drive unit including a motor and gears shown in FIG.

2a is a laser scanner for black (Bk), 2b is a laser scanner for cyan (C), 2c is a laser scanner for magenta (M), and 2d is a laser scanner for yellow (Y). Exposure is performed in accordance with each image signal to form an electrostatic latent image on each of the photosensitive drums 1a to 1d.

The black image forming section includes a photosensitive drum 1a, a laser scanner 2a and the like. The cyan image forming unit includes a photosensitive drum 1b, a laser scanner 2b, and the like. The magenta image forming unit includes the photosensitive drum 1
c, a laser scanner 2c and the like. The yellow image forming section includes a photosensitive drum 1d, a laser scanner 2d, and the like.

Reference numeral 3 denotes an endless transport belt, which sequentially transports a sheet as a recording medium to each color image forming unit and also serves as a transfer belt for transferring each color image formed by each color image forming unit to recording paper. . A driving roller 4 is connected to a driving unit including a motor and gears shown in FIG. 5 is a driven roller,
The conveyor belt 3 rotates according to the movement of the conveyor belt 3 and
A constant tension.

The operation of each section will be described below.

Data (print information) to be printed is input from an external device such as a computer (PC) (not shown), and when image processing according to the printer engine is completed and the printer is ready for printing, paper from a paper cassette (not shown) Is supplied and arrives at the conveyor belt 3, and the conveyor belt 3
, The paper is sequentially conveyed to the image forming units of each color.

The image signals of the respective colors are supplied to the respective laser scanners 2a to 2a in synchronism with the sheet conveyance by the conveyor belt 3.
d, each of the laser scanners 2a to 2d irradiates a laser beam to form an electrostatic latent image on each of the photosensitive drums 1a to 1d, and a developing unit (not shown) is formed on each of the photosensitive drums 1a to 1d. The electrostatic latent image is developed with toner, and the toner images on the photosensitive drums 1a to 1d are transferred onto a sheet conveyed by a conveying belt by a transfer unit (not shown). In this embodiment, yellow (Y), magenta (M), cyan (C),
Images are sequentially formed in the order of black (Bk). Thereafter, the sheet on which the toner image has been transferred is separated from the transport belt, and the toner image is fixed on the sheet by heat in a fixing device (not shown) and discharged to the outside.

FIG. 2 is a block diagram for explaining a drive configuration of the image forming apparatus according to the first embodiment of the present invention.
The same components as those described above are denoted by the same reference numerals.

In the figure, reference numeral 7 denotes a rotating shaft of the photosensitive drums 1a to 1d or the driving roller 4, and the photosensitive drums 1a to 1d
d or with the drive roller 4. Hereinafter, the case of the photosensitive drums 1a to 1d will be described. In addition, the following configuration is provided for each of the photosensitive drums 1a to 1d, and the photosensitive drums 1a to 1d are hereinafter collectively referred to as a photosensitive drum 1.

Numeral 8 denotes a stepping motor, which is a drive source for rotatingly driving the photosensitive drum 1 (or the driving roller 4 of the conveyor belt) in accordance with the frequency of the stepping motor drive pulse that is set. Reference numeral 6 denotes a reduction gear, which transmits the rotation of the stepping motor 8 to the rotating shaft 7. Reference numeral 9 denotes a code wheel, which is provided with slits at equal intervals on a concentric circle and rotates together with the rotating shaft 7. Reference numeral 10 denotes an encoder, which includes a light emitting unit and a light receiving unit, and outputs a pulse signal according to the passage of the slit of the code wheel 9. Reference numeral 11 denotes a control unit that performs arithmetic processing on a pulse output output from the encoder 10 in accordance with the rotation of the code wheel 9 attached to the rotating shaft 7 and controls the rotation of the motor 8.

Note that the stepping motor 8 has a rotation 20
It is a 0-step hybrid two-phase stepping motor, which is theoretically driven at 2000 pps (600 rpm). The speed is reduced to "1/12" by the reduction gear 6, and the photosensitive drum 1 rotates at 50 rpm. Code wheel 9
Has 800 slits, and the encoder 10 outputs 800 pulses in one rotation of the photosensitive drum 1. The “1” pulse of the encoder 10 corresponds to “3 (= 200 × 12/800)” steps of the stepping motor 8.

Before explaining the correction of the rotation unevenness of the photosensitive drum 1 by the control unit 11, FIGS.
With reference to FIG.
The non-stationary color shift in the sub-scanning direction caused by the rotation unevenness (that is, the unevenness of conveyance of the recording medium) will be described.

FIG. 3 is a characteristic diagram showing the cycle irregularity of the pulse output by the encoder 10 shown in FIG.

In the figure, (a) shows the transition of the pulse output cycle of the encoder 10, in which the horizontal axis corresponds to time and the vertical axis corresponds to the pulse output cycle of the encoder 10.

As shown in (a), the rotation of the photosensitive drum 1 is not constant due to the uneven rotation of the stepping motor 8 or the dimensional error (meshing error) of the reduction gear 6, and the like.
The output pulse period of 0 fluctuates.

(B) shows the transition of the position error of the photosensitive drum 1 as the integral value of the output pulse period of the encoder 10 shown in (a), the horizontal axis corresponds to time, and the vertical axis represents the encoder. This corresponds to a position error which is an integral value of ten output pulse periods.

As shown in (b), a position error of the photosensitive drum 1, which is a value obtained by integrating the output pulse period of the encoder 10 shown in (a), periodically occurs. The phase and amplitude of the position error differ for each color (photosensitive drums 1a to 1d), resulting in a periodic color shift.

FIG. 4 is a view for explaining an unsteady color shift in the sub-scanning direction caused by uneven rotation of the photosensitive drum 1 shown in FIG.

This shows a case where color misregistration has occurred between black Bk and yellow Y. The total movement is black (Bk)
And yellow (Y), but the phase and amplitude of the rotation unevenness are different between black (Bk) and yellow (Y), and a color shift (approaching or moving away) occurs periodically.

FIG. 5 is a block diagram for explaining the configuration of the control unit 11 shown in FIG. 2 in detail. The same components as those in FIG. 2 are denoted by the same reference numerals.

In the figure, reference numeral 301 denotes an encoder cycle counter which counts the pulse cycle of the encoder 10.
Reference numeral 302 denotes an encoder cycle error calculation unit which calculates an error between a pulse cycle count value of the encoder 10 by the encoder cycle counter 301 and a theoretical value. An encoder cycle pulse rate memory 303 stores an error between the pulse cycle count value of the encoder 10 and a theoretical value calculated by the encoder cycle error calculation unit 302.

Reference numeral 304 denotes a filter operation unit which removes high-frequency components having no periodicity due to the tooth pitch of the reduction gear 6 by a filter process (LPF: low-pass filter). For “n”, (n−m + 1) to (n−m + 1) held in the encoder cycle pulse rate memory 303.
An average value of errors in m sections up to n is obtained. A pulse rate correction value calculation unit 305 calculates a pulse rate of the stepping motor 8 to cancel the error from the average value of the errors in the m section input from the filter calculation unit 304.

A pulse rate register 306 holds the pulse rate of the stepping motor 8 calculated by the pulse rate correction value calculation section 305. A pulse rate counter 307 counts the pulse rate held in the pulse rate register 306. Reference numeral 308 denotes a phase signal generation unit which generates a phase signal according to the pulse rate held by the pulse rate register 306 and counted by the pulse rate counter 307.

A motor driver 309 drives the stepping motor 8 by the phase signal generated by the phase signal generator 308.

The configuration of the control unit 11 shown in FIG.
Even if it is configured to be realized by hardware (H / W), it is realized by software (S / W), that is, a CPU (not shown) that controls the control unit 11 in the control unit 11.
ROM, CP (not shown) for storing programs to be executed
A RAM (not shown), which is a work area for U, is provided.
The configuration of the control unit 11 shown in FIG. 5 may be realized by executing a program stored in the OM.

FIG. 6 shows the error of the pulse cycle of the encoder 10 (calculated by the encoder cycle error calculator 302 shown in FIG. 5) and the correction value of the step cycle of the stepping motor 8 (the pulse rate shown in FIG. 5). Correction value calculator 3
FIG. 5 is a diagram for explaining the relationship between the two.

In the figure, E1 to E3 are encoder pulse Nos. Where ΔE1 to ΔE3 are errors of the encoder pulse period after the LPF (after the LPF), and the encoder pulse N
o. E1 to E3, corresponding to the encoder cycle error calculation unit 3
02 is subjected to an error operation and subjected to LPF processing by the filter operation unit 304. M1 to M7 are motor step numbers. (FG No. in the case of a DC brushless motor 1008 shown in a second embodiment described later).
To .DELTA.M7 are motor correction values. M1
, And is calculated by the pulse rate correction value calculation unit 305. Here, a is a coefficient, and the motor correction value ΔM is calculated based on the error ΔE of the encoder pulse period.
Is a correction coefficient for calculating.

The control procedure of the control unit 11 based on the relationship between the error of the pulse cycle of the encoder 10 and the correction value of the step cycle of the stepping motor 8 shown in FIG. 6 will be described below.

The pulse rate correction value calculation section 305 calculates an error by the encoder cycle error calculation section 302 and performs LPF (filter processing) by the filter calculation section 304 on the encoder pulse No. 1 (1st pulse of encoder)
Multiplied by the coefficient a to the error ΔE1 of the
(Because the output frequency of the encoder 10 and the driving frequency of the stepping motor are “1: 3”), and a motor correction value (pulse rate correction value) Δ for canceling the error.
Calculate M1.

Next, according to the (pulse rate correction value) calculated by the pulse rate correction value calculation unit 305, the motor 8
Is corrected every three steps. Less than,
The same operation is repeated.

Note that one pulse of the encoder 10 corresponds to three steps of the stepping motor 8, but has a one-to-one correspondence in arithmetic processing as described above.

Referring now to FIG. 7, the result of correction of uneven rotation of photosensitive drum 1 by control unit 11 shown in FIG. 3 will be described.

FIG. 7 is a characteristic diagram showing the cycle unevenness of the pulse output from the encoder 10 shown in FIG. 2 after the correction by the control unit 11 shown in FIG. 3. As shown in FIG.
(A) shows the transition of the pulse output cycle of the encoder 10, and (b) shows the transition of the position error which is the integral value of the output pulse cycle of the encoder 10 shown in (a).

When the control unit 11 controls the rotation of the stepping motor 8 based on the output of the encoder 10, the rotation unevenness and the position error of the photosensitive drum 1 are suppressed as shown in FIGS. Color shift is reduced.

In this embodiment, the case where the motor correction value is calculated based on the periodic error of the output signal of the encoder 10 has been described, but the motor correction value is calculated based on the frequency (1 / period) error of the output signal of the encoder 10. It goes without saying that the correction value may be calculated.

From the above, using the encoder error as a variable,
Since only one type of calculation formula such as a product-sum calculation is required for obtaining the motor correction value including the filter processing, the amount of calculation of the motor correction value of the stepping motor 8 can be reduced to reduce the circuit scale and the amount of programs, and to reduce In addition, it is possible to control the rotation unevenness of the photosensitive drums 1a to 1d (that is, the unevenness of conveyance of the recording medium) with high accuracy to prevent the color misregistration.

In this embodiment, the photosensitive drums 1 for each color are used.
The drive unit shown in FIG. 2 (the control frequency of the stepping motor 8 which is the drive source of the photosensitive drum 1 and the photosensitive drum 1
The output frequency of the encoder 10 for detecting the rotation state of the motor 10 is an integer multiple ratio, and the control unit 11 controls the drive cycle of the stepping motor 8 based on the output signal from the encoder 10 in each drive unit. Although the case where the color shift is reduced by controlling the transport unevenness with high speed and high accuracy has been described, since the image is sequentially transported to the image forming unit of each color component by the transport belt 3, the transport unevenness of the transport belt 3 In addition, color misregistration occurs as in the case of the photosensitive drum 1.

Therefore, in addition to the photosensitive drums 1a to 1d, the drive unit shown in FIG. 2 (the control frequency of the stepping motor 8 which is the drive source of the photosensitive drum 1, the stepping motor 8 Encoder 10 for detecting the rotation state of photosensitive drum 1 rotated and driven by
The output frequency of the photosensitive drum 1a
1d and the driving unit of the driving roller 4, the control unit 11 controls the driving cycle of the stepping motor 8 based on the output signal from the encoder 10 to control the transport unevenness at high speed and with high accuracy to reduce the color misregistration. You may comprise so that it may reduce.

As described above, in addition to the photosensitive drums 1a to 1d, the encoder 1 for further detecting the rotation state of the transport belt 3
Since only one type of calculation formula such as a product-sum calculation is required for obtaining a motor correction value using the encoder error of 0 as a variable, the amount of calculation of the motor correction value of the stepping motor 8 which is the driving source of the conveyor belt 3 can be reduced. To reduce the circuit scale and the amount of programming, and to achieve high-speed and high-precision
The color shift can be prevented by controlling the rotation unevenness of a to 1d and the conveyance belt 3 (that is, the conveyance unevenness of the recording medium).

[Second Embodiment] In the first embodiment,
The case where each of the photosensitive drums 1a to 1d and the drive roller 4 are driven by the stepping motor 8 has been described.
The photosensitive drums 1a to 1d and the driving roller 4 may be configured to be driven by a DC brushless motor. Hereinafter, the embodiment will be described.

FIG. 8 is a block diagram for explaining a drive configuration of an image forming apparatus according to a second embodiment of the present invention.
The same components as those described above are denoted by the same reference numerals.

In the figure, reference numeral 1008 denotes a DC brushless motor, which is a drive source for the photosensitive drum 1 or the drive roller 4 for rotating the photosensitive drum 1 (or the drive roller 4) in accordance with the frequency of a set FG pulse (described later). It is.
Reference numeral 1011 denotes a control unit which performs arithmetic processing on a pulse output output from the encoder 10 in accordance with the rotation of the code wheel 9 attached to the rotating shaft 7, and
008 is controlled.

FIG. 9 is a block diagram for explaining in detail the configuration of the DC brushless motor 1008 and the control unit 1011 shown in FIG. 8, and the same components as those in FIG. 5 are denoted by the same reference numerals.

In the figure, reference numeral 901 denotes an FG (Freque
A pulse generator generates a pulse according to the rotation of the rotor of the DC brushless motor 1008. Reference numeral 902 denotes an error counter (comparator) that compares the period of the FG signal output from the FG signal generation unit 901 with the value held in the pulse rate register 306, and
The error of the signal cycle is output. Reference numeral 903 denotes a filter unit.
Performs gain adjustment and phase compensation. 904 is a driver unit (P
WM control), FG output from error counter 902
The pulse width of the motor drive signal is controlled (PWM) so that the FG signal cycle matches the value held in the pulse rate register 306 based on the error of the signal cycle.

The operation of each unit will be described below.

The processing from the encoder 10 to the pulse rate correction value calculating section 305 is the same as the operation shown in FIG. 5 of the first embodiment.
The pulse cycle of the encoder 10 is counted, and the encoder cycle error calculation unit 302
The difference between the pulse cycle count value of the encoder 10 and the theoretical value by 1 is obtained and stored in the encoder cycle pulse rate memory 303.

Next, the filter operation unit 304 removes high-frequency components having no periodicity due to the tooth pitch of the reduction gear 6 by a filter process (LPF: low-pass filter).
Encoder pulse No. “N” is stored in the encoder cycle pulse rate memory 303 (n−m +
1) Calculate the average value of errors in m sections from n to n. next,
The pulse rate correction value calculation unit 305 includes the filter calculation unit 3
DC brushless motor 1008 that cancels the error from the average value of the error in the m section input from input unit 04
Of the DC brushless motor 100
8 is held in the pulse rate register 306.

Next, the error counter 902 compares the period of the FG signal generated by the FG signal generator 901 with the value held in the pulse rate register 306, and outputs an error of the FG signal period.

Next, the filter unit 903 performs gain adjustment and phase compensation, the driver unit 904 controls (PWM) the pulse width of the motor drive signal, and the FG signal period is the value held in the pulse rate register 306. The rotation of the DC brushless motor 1008 is controlled so as to match.

The F of the DC brushless motor 1008
The FG signal output from the G signal generation unit 901 is
With 0 pulse, the DC brushless motor 1008 is driven at 1200 rpm theoretically. The speed is reduced to "1/24" by the reduction gear 6, and the photosensitive drum 1 rotates at 60 rpm. The code wheel 9 has 800 slits, and one rotation of the photosensitive drum 1 causes the encoder 10 to 80 to rotate.
0 pulses are output. The “1” pulse of the encoder 10 is “3” of the FG signal of the DC brushless motor 1008.
(= 100 × 24/800) ”pulse.

The configuration of the control unit 1011 and the DC brushless motor 1008 shown in FIG. 9 can be realized by software (S / W) even if it is realized by hardware (H / W). That is, a CPU (not shown) for controlling the control unit 1011, a ROM (not shown) for storing a program to be executed by the CPU, and a RAM (not shown) as a work area of the CPU are provided in the control unit 1011, and the CPU stores the program in the ROM. The control unit 1 shown in FIG.
011 and the configuration of the DC brushless motor 1008 may be realized.

The error of the pulse period of the encoder 10 of the first embodiment shown in FIG.
The relationship between the step value of the stepping motor 8 and the correction value of the step period is as follows. DC brushless motor 1
008 FGNo. , The error of the pulse cycle of the encoder 10 (calculated by the encoder cycle error calculation unit 302 shown in FIG. 9) and the correction value of the FG cycle of the DC brushless motor 1008 (the pulse rate correction shown in FIG. 9). (Calculated by the value calculation unit 305), and based on this relationship, the pulse rate correction value calculation unit 305 determines the F of the DC brushless motor 1008.
A correction value for the G cycle is calculated. However, the value of the coefficient a is shown in FIG.
The coefficient a corresponds to the relationship between the error of the pulse cycle of the encoder 10 and the correction value of the FG cycle of the DC brushless motor 1008.

As in the first embodiment, the “1” pulse of the encoder 10 is
"3" pulse, but the calculation processing is one-to-one.
It becomes correspondence.

Therefore, the first embodiment shown in FIGS.
As shown in (b), the rotation unevenness and the position error of the photosensitive drum 1 are suppressed, and the color shift is reduced.

In this embodiment, the case has been described where the motor correction value is calculated based on the periodic error of the output signal of the encoder 10. However, the motor correction value is calculated based on the frequency (1 / period) error of the output signal of the encoder 10. It goes without saying that the correction value may be calculated.

From the above, using the encoder error as a variable,
Since only one type of calculation formula such as a product-sum calculation for obtaining the motor correction value including the filter processing is required, the amount of calculation of the motor correction value of the DC brushless motor 1008 is reduced to reduce the circuit scale and the amount of programs. It is possible to control the rotation unevenness of the photosensitive drums 1a to 1d (and the drive roller 4) (i.e., the unevenness of conveyance of the recording medium) at high speed and with high accuracy to prevent color misregistration.

In the first and second embodiments, the case where the output pulse cycle of the encoder 10 and the step cycle of the stepping motor 8 (the FG signal cycle of the DC brushless motor 1008) are "1: 3" has been described. But,
The output pulse cycle of the encoder 10 and the step cycle of the stepping motor 8 (F of the DC brushless motor 1008
(G signal period) may be simply an integer ratio.

[Third Embodiment] In the first and second embodiments, the code wheel 9 has 800 slits, and the “1” pulse of the encoder 10 is “3 (= 200 × 12 / 800) ”step (3 (= 100 × 2) of the FG signal of the DC brushless motor 1008.
4/800) "pulse), that is, the case where the rotational state detection frequency by the encoder 10 and the drive frequency of the stepping motor 8 (DC brushless motor 1008) are an integral multiple ratio.
And the stepping motor 8 (D
The driving frequency of the C brushless motor 1008) may be a power of 2 (2 to the power of n, where n is an integer). Hereinafter, the embodiment will be described.

In this embodiment, the code wheel 9 has 12
00 (or 600) slits and the encoder 10
The “1” pulse of “2” (= 20) of the stepping motor 8
0 × 12/1200) ”or“ 4 (= 200 × 12 /
600) step (“2 (= 100 × 24/1200)” or “4 (= 200 × 12/600)” pulses of the FG signal of the DC brushless motor 1008).

FIG. 10 shows an error of the pulse cycle of the encoder 10 of the image forming apparatus according to the third embodiment of the present invention and the stepping motor 8 (DC brushless motor 1008).
7 is a diagram showing the relationship with the correction value of FIG. 6, and the same components as those in FIG. 6 are denoted by the same reference numerals.

FIG. 10 shows the state of “1” of the encoder 10.
The pulse is “2 (= 200 × 12) of the stepping motor 8.
/ 1200) "step (DC brushless motor 100
Only the case corresponding to “2 (= 100 × 24/1200)” pulses of 8 FG signals is shown.

The control unit 11 (control unit 1011) based on the relationship between the error of the pulse cycle of the encoder 10 and the correction value of the step cycle of the stepping motor 8 (FG cycle of the DC brushless motor 1008) shown in FIG. ) Will be described.

The pulse rate correction value calculation section 305 calculates an error by the encoder cycle error calculation section 302 and performs LPF (filter processing) by the filter calculation section 304 on the encoder pulse No. 1 (1st pulse of encoder)
At the same time as multiplying the error ΔE1 by
(Or “1/4”) (in this case, a shift operation of “1” or “2” may be performed), and a motor correction value (pulse rate correction value) ΔM1 for canceling the error is calculated.

Next, the drive pulse cycle of the stepping motor 8 (DC brushless motor 1008) is corrected every two or four steps in accordance with the (pulse rate correction value) calculated by the pulse rate correction value calculator 305. Less than,
The same operation is repeated.

One pulse of the encoder 10 corresponds to two or four steps of the stepping motor 8 (DC brushless motor 1008), but has a one-to-one correspondence in arithmetic processing as described above.

As described above, in the case of the present embodiment, the pulse No. And step No. of the stepping motor 8. (FGN of DC brushless motor 1008
o. ) Corresponds to two or four, ie, “2 to the first power” or “2 to the second power”, so that “１ ／” times or “1/2”
The digital operation processing of "4" times (division by "2" or "4") becomes the shift operation of "1" or "2", and is the "1/3" times shown in the first and second embodiments. Compared to digital arithmetic processing (division by “3”), processing can be performed at a much higher speed.

Further, in the present embodiment, the case where the output pulse cycle of the encoder 10 and the step cycle of the stepping motor 8 (the FG signal cycle of the DC brushless motor 1008) have a ratio of "2" or "4" has been described. But,
The output pulse cycle of the encoder 10 and the step cycle of the stepping motor 8 (F of the DC brushless motor 1008
The ratio with respect to the G signal period may be simply “power-of-two ratio (n-th power ratio, where n is an integer)”.

In this embodiment, the case has been described where the motor correction value is calculated based on the periodic error of the output signal of the encoder 10. However, the motor correction value is calculated based on the frequency (1 / period) error of the output signal of the encoder 10. It goes without saying that the correction value may be calculated.

As described above, the ratio between the frequency for detecting the rotation state of the photosensitive drum and the driving roller of the transport belt and the control frequency of the motor as the driving source is a power of 2 (2 n times, where n is an integer). Therefore, in digital arithmetic processing,
Operation to convert the difference between the number of detections and the number of corrections (division, multiplication)
However, since the shift operation is performed, the circuit scale and the program amount can be further reduced, and the processing can be performed at a higher speed. Therefore, the transport unevenness can be controlled at a higher speed, and the color shift can be reduced.

In the present embodiment, the case where the photosensitive drum is used as the latent image forming medium has been described. However, the latent image forming medium is constituted by a belt-shaped photosensitive member, and the belt-shaped photosensitive member is suspended and is It may be configured to be driven.

A stepping motor is used as a driving source.
Although the case where the DC brushless motor is used has been described, the motor as the driving source may be constituted by another motor such as a DC servo motor with a plan.

Furthermore, the case where the optical encoder constituted by the light emitting section and the light receiving section is described, but the optical encoder may be a reflection type.

The rotation state of the photosensitive drum and the like is detected by
Although the description has been given of the case where the operation is performed using the code wheel and the optical encoder, a magnetic rotary encoder using an MR element or the like may be used.

Further, the case where the frequency of the encoder for detecting the rotation state of the photosensitive drum or the like is lower than the frequency of the drive source of the photosensitive drum or the like has been described. May be higher than the frequency of the driving source such as the photosensitive drum.

Also, a case has been described in which data (print information) to be printed is input from an external device such as a computer (PC) (not shown). However, printing is performed by optically reading a document image by a document reading device (not shown). Data (print information) to be input may be configured.

Further, the case where a color image is formed by four color components of yellow (Y), magenta (M), cyan (C) and black (Bk) has been described. Or any number of colors other than four.

As described above, an image forming apparatus that calculates a motor correction value including a filter process (LPF: low-pass filter) using an error of a detection signal of a rotation state of a photosensitive drum, a conveyance belt driving roller, or the like as a variable. Since the ratio between the detection frequency of the rotation state of the photosensitive drum and the transport belt drive roller and the control frequency of the motor that is the drive source of the photosensitive drum and the transport belt drive roller is an integral multiple, the motor correction value is calculated. A single type of calculation formula such as a product-sum operation may be used, and the circuit scale and the program amount for calculating the motor correction value are reduced, and the processing speed is increased. The amount of calculation is reduced, the transport unevenness is controlled at high speed and with high accuracy, and the color caused by the rotational unevenness of the photosensitive drum and the transport belt drive roller (ie, the transport unevenness of the recording medium). Le can be reduced efficiently.

Further, in addition to a latent image forming medium such as a photosensitive drum, there is provided a means for detecting a rotation state of an endless belt such as a transport belt which sequentially passes through the image forming sections of each color, so that a higher accuracy is provided. By controlling the transport unevenness, it is possible to efficiently and reliably reduce the color shift caused by the rotation unevenness of the photosensitive drum and the transport belt driving roller (that is, the transport unevenness of the recording medium).

Further, the ratio of the frequency for detecting the rotation state of the photosensitive drum, the conveyor belt drive roller and the like to the control frequency of the motor as the drive source is "2 to the power of n (integer)" times. In the calculation processing, calculation (division, multiplication) that converts the difference between the number of rotation state detections and the number of corrections
However, since this is a shift operation, the circuit scale and the amount of programming can be further reduced, and the processing speed can be further increased. In other words, it is possible to more efficiently and surely reduce the color misregistration caused by the recording medium conveyance unevenness.

Further, the present invention is applicable not only to the drive stability control of the image forming apparatus but also to the drive stability control of other apparatuses.

Further, the embodiments may be combined.

As described above, the storage medium storing the program codes of the software for realizing the functions of the above-described embodiments is supplied to the system or the apparatus, and the computer (or CPU or MP) of the system or the apparatus is supplied.
It goes without saying that the object of the present invention is also achieved when U) reads out and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes a novel function of the present invention, and the storage medium storing the program code constitutes the present invention.

Examples of the storage medium for supplying the program code include a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM,
DR, magnetic tape, nonvolatile memory card, RO
M, EEPROM and the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) And the like perform part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, The CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus. In this case, by reading a storage medium storing a program represented by software for achieving the present invention into the system or the apparatus, the system or the apparatus can enjoy the effects of the present invention. .

Further, by downloading and reading out a program represented by software for achieving the present invention from a database on a network by a communication program, the system or apparatus can be
It is possible to enjoy the effects of the present invention.

[0124]

As described above, the first embodiment according to the present invention is described.
According to the third invention, the third invention, the fourth invention, the sixth invention, and the seventh invention, a plurality of image forming units provided for each color component form a color component image on a plurality of image carriers. A multi-color image is formed by forming the respective color component images formed on the respective image carriers and superimposing and transferring the color component images onto a recording medium conveyed by an endless belt-shaped moving body sequentially passing through the respective image carriers. In a possible image forming apparatus, a first pulse signal having a frequency which is an integral multiple of a frequency of each drive signal individually set for each of the plurality of image carrier driving sources for rotating each of the image carriers is provided. Based on the frequency error of the first pulse signal generated by each of the plurality of image carrier rotation state detectors in accordance with the rotation of each of the image carriers, a plurality of image carrier rotation control units are configured to control each of the image carriers. Controls the frequency of the drive signal set for the drive source Therefore, the motor correction value for correcting the rotation unevenness of the photosensitive drum or the like can be calculated by a single product-sum operation, and the circuit scale and the program amount for calculating the motor correction value can be reduced. With
It is possible to efficiently reduce a color shift caused by uneven rotation of a photosensitive drum, a conveyance belt driving roller, and the like.

According to the second, fifth, eighth, and ninth aspects of the invention, the endless belt-shaped moving body is suspended via a predetermined drive roller based on the frequency of the set drive signal. A driving roller driving source for driving the endless belt-shaped moving body, and a second pulse having a frequency that is an integral multiple of a frequency of a driving signal set in the driving roller driving source in accordance with the rotation of the driving roller. A driving roller rotation state detecting unit for generating a signal, and a frequency of a driving signal set in the driving roller driving source are controlled based on a frequency error of a second pulse signal generated by the driving roller rotation state detecting unit. And a motor correction value for correcting the rotation unevenness of the transport belt driving roller and the like in addition to the rotation unevenness of the photosensitive drum is calculated by a single product-sum operation. It is possible to further reduce the circuit scale and the program amount for calculating the motor correction value, and it is possible to efficiently reduce the color misregistration due to the uneven rotation of the photosensitive drum and the transport belt driving roller. .

According to the tenth aspect, each of the image carrier rotation state detecting means is configured to output a driving signal of each of the image carrier driving sources individually set in accordance with the rotation of each of the image carriers. Since each of the first pulse signals having a frequency which is a power of 2 of the frequency is generated, a digital operation (division, multiplication) for calculating a motor correction value for correcting rotation unevenness of the photosensitive drum or the like is performed by a shift operation. Thus, the circuit scale and the program amount for calculating the motor correction value can be further reduced, and the color misregistration caused by uneven rotation of the photosensitive drum, the conveyance belt driving roller, and the like can be reduced more efficiently.

According to the eleventh aspect, the drive roller rotation state detecting means is responsive to the rotation of the drive roller, the frequency being a power of 2 of the frequency of the drive signal set in the drive roller drive source. , A digital operation (division, division) for calculating a motor correction value for driving the photosensitive drum, the conveyance belt driving roller, and the like.
Multiplication) becomes a shift operation, which can further reduce the circuit scale and program amount for calculating the motor correction value, and efficiently and reliably prevent color misregistration caused by uneven rotation of the photosensitive drum and the transport belt drive roller. Can be reduced.

Therefore, the motor correction value for correcting the rotation unevenness of the photosensitive drum or the like can be calculated by a single product-sum operation, so that the circuit scale and the amount of programs can be reduced, and the conveyance of the recording medium can be performed. There are effects such as the ability to efficiently reduce color misregistration caused by unevenness.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus according to a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram illustrating a driving configuration of the image forming apparatus according to the first exemplary embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a period variation of a pulse output by the encoder shown in FIG. 2;

FIG. 4 is a diagram illustrating an unsteady color misregistration in the sub-scanning direction caused by uneven rotation of the photosensitive drum illustrated in FIG. 3;

FIG. 5 is a block diagram illustrating a configuration of a control unit illustrated in FIG. 2 in detail.

FIG. 6 is a diagram illustrating the relationship between an error in a pulse cycle of an encoder and a correction value of a step cycle of a stepping motor.

FIG. 7 is a characteristic diagram showing the period unevenness of a pulse output by the encoder shown in FIG. 2 after correction by the control unit shown in FIG. 3;

FIG. 8 is a block diagram illustrating a driving configuration of an image forming apparatus according to a second exemplary embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of a DC brushless motor and a control unit illustrated in FIG. 8 in detail.

FIG. 10 is a diagram illustrating a relationship between an error of a pulse cycle of an encoder of an image forming apparatus according to a third embodiment of the present invention and a correction value of a stepping motor (DC brushless motor).

FIG. 11 is a diagram illustrating a relationship between an error of an encoder pulse which is a rotation state detection signal of a photosensitive drum of a conventional image forming apparatus and a correction value of a stepping motor cycle.

[Explanation of symbols]

 1a to 1d Photosensitive drums 2a to 2d Laser scanner 3 Conveyor belt 4 Drive roller 8 Stepping motor 10 Encoder 11 Control means 302 Encoder cycle error calculation section 305 Pulse rate correction value calculation section 1011 Control means 1008 DC brushless motor

Claims (11)

[Claims] 1. A plurality of image forming units provided for each color component form a color component image on a plurality of image carriers, respectively. In an image forming apparatus capable of forming a multicolor image by superimposing and transferring a recording medium conveyed by an endless belt-shaped moving body that sequentially passes through an image carrier, the image forming apparatus includes: A plurality of image carrier driving sources for respectively driving the image carriers; and an integral multiple of the frequency of each drive signal individually set for each of the image carrier driving sources in accordance with the rotation of each of the image carriers. A plurality of image carrier rotation state detecting means for respectively generating a first pulse signal of a certain frequency; and, based on a frequency error of the first pulse signal generated by each of the image carrier rotation state detecting means, Drive set as the image carrier drive source An image forming apparatus comprising: a plurality of image carrier rotation control means for controlling a frequency of a motion signal. 2. A drive roller drive source for driving the endless belt-shaped moving body via a predetermined driving roller on which the endless belt-shaped moving body is suspended based on a frequency of a set drive signal, and the driving roller A driving roller rotation state detecting unit that generates a second pulse signal having a frequency that is an integral multiple of a frequency of a driving signal set in the driving roller driving source in accordance with the rotation of the driving roller; 2. A control device for controlling a frequency of a drive signal set to the drive roller drive source based on a frequency error of a second pulse signal generated by the control unit. Image forming apparatus. 3. Each of the image carriers is formed in a drum shape, and each of the image carrier rotation state detecting means is a rotary encoder provided on an extension of the drum shaft. 3. The image forming apparatus according to claim 1, wherein the frequency of the first pulse signal generated by the state detection unit is an output frequency of each rotary encoder. 4. Each of the image carriers is formed in an endless belt shape, and each of the image carrier driving sources is provided with a predetermined drive roller formed in an endless belt shape and on which each of the image carriers is suspended. The image carrier rotation state detecting means is a rotary encoder provided on an extension of each of the drive roller shafts, and the image carrier rotation state detection means generates 3. The image forming apparatus according to claim 1, wherein the frequency of the first pulse signal is an output frequency of each rotary encoder. 5. The drive roller rotation state detection means is a rotary encoder provided on an extension of the drive roller shaft, and the frequency of the second pulse signal generated by the drive roller rotation detection means is a rotary encoder. 3. The image forming apparatus according to claim 2, wherein the output frequency of the image forming apparatus is the following. 6. The image carrier drive source is a stepping motor, and a frequency of a drive signal set for each image carrier drive source is a drive pulse frequency of the stepping motor. The image forming apparatus according to claim 1. 7. Each of the image carrier driving sources generates a third pulse signal according to the rotation state of each image carrier driving source.
The image forming apparatus according to claim 1, wherein the image forming apparatus is a C brushless motor, wherein a frequency of a driving signal set to each of the image carrier driving sources is a frequency of a third pulse signal. 8. The driving roller driving source is a stepping motor, and the frequency of the driving signal set in the driving roller driving source is a driving pulse frequency of the stepping motor. Image forming apparatus. 9. The driving roller driving source generates a third pulse signal according to a rotation state of each image carrier driving source.
3. The image forming apparatus according to claim 2, wherein the frequency of the driving signal set in the driving roller driving source is a frequency of a third pulse signal. 4. 10. The image carrier rotation state detecting means,
Generating a first pulse signal having a frequency which is a power-of-two ratio of a frequency of each drive signal individually set to each of the image carrier driving sources in accordance with the rotation of each of the image carriers. The image forming apparatus according to claim 1, wherein: 11. The driving roller rotation state detecting means,
3. The method according to claim 2, wherein a second pulse signal having a frequency that is a power of 2 of a frequency of a drive signal set in the drive roller drive source is generated in accordance with the rotation of the drive roller. Image forming device.