JP2001305820A - Color image forming system and method for correcting color slippage of it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce relative color slippage by simply correcting deviation in rotational phase of each image carrier. SOLUTION: A detecting part 44 detects the angular speed fluctuation of each photosensitive drum by reading a pattern image which is formed by each photoreceptive drum and transferred to a transportation belt 2. Based on the angular speed fluctuation detected, a motor control part 103 adjust/controls the drive speed of a motor 41 to detect phase difference of each gear by the part 44. Based on the phase information which is detected, the motor control part 103 adjusts/controls the phase of a photoreceptor drum 1 of each color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a plurality of image carriers which are arranged side by side, and each of the image carriers has a plurality of driving means for rotating by driving a gear for one-step reduction. The present invention relates to a color image forming apparatus for forming a color image by successively superimposing and transferring a color image formed thereon on a recording medium conveyed by an endlessly moving conveyance body, and a color misregistration correction method for the color image forming apparatus.

[0002]

2. Description of the Related Art There has been proposed a so-called in-line type color image forming apparatus in which a plurality of photosensitive drums are arranged in a line. This is because, while carrying and transporting the transfer material by an electrostatic transfer belt stretched by a plurality of rollers, four photosensitive drums arranged along the transfer material transport path,
A toner image composed of yellow (Y), magenta (M), cyan (C), and black (Bk) is sequentially transferred onto a sheet, and a color image is formed by superimposing the respective colors. This configuration has attracted attention in recent years because printing can be performed at high speed.

However, since each color is formed by four photosensitive drums, a configuration in which colors are superimposed on one photosensitive drum via four transport paths for each color (hereinafter, referred to as a "4-pass method") Further accuracy is required for the rotational drive of the photosensitive drum as compared with the color image forming apparatus described above.

That is, generally, the photosensitive drum is driven by:
A gear train is adopted, and low-frequency rotation unevenness such as one rotation component of the gear always occurs. However, in the case of the four-pass method, the cumulative pitch error of the gear is obtained by setting the reduction ratio of the drive gear train to an integer combination. And the like can be avoided and the image forming position of each color can be matched.

However, in the case of the in-line system, since the plurality of photosensitive drums are independent, the drive gear train is also independent, and it is difficult to avoid the above-described four-pass system, so that the image forming position of each color is shifted. Image quality degradation such as color misregistration is likely to occur.

Conventionally, as a countermeasure against color misregistration, a method of detecting the angular velocity of a photosensitive drum or reading an image transferred to a transfer material to detect speed unevenness, and controlling the rotation of a motor so as to cancel out the speed unevenness. In addition, measures have been taken to reduce the relative color shift by adjusting the rotational phase of each photosensitive drum to a desired state.

[0007]

However, in the above-mentioned conventional example, the photosensitive drum is driven by a reduction system through a plurality of gears. Becomes a complicated velocity waveform including the component of one rotation cycle of the above. Therefore, there is a problem that a highly accurate speed unevenness detecting means and a motor control are required, and the influence of the intermediate gear remains even when the phases of the photosensitive drums are adjusted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a plurality of image carriers in parallel, and engage a gear that reduces the speed by one stage with each image carrier. A color image forming apparatus comprising a plurality of driving means for rotating and driving, and sequentially transferring a color image formed on each image carrier onto a recording medium conveyed by an endlessly moving conveyance body to form a color image In the apparatus, the angular velocity fluctuation of each image carrier is detected by reading a pattern image formed by each image carrier and transferred to the carrier, and the phase difference of each gear engaged with the image carrier is detected. Based on the detected angular velocity fluctuation and the phase information of the detection gear, by adjusting and controlling the phase of the driving means, or by forming a pattern image formed by each image carrier and transferred to the carrier. Read By detecting the angular velocity fluctuation of each image carrier, and detecting the phase difference of each gear engaged with the image carrier, based on the detected angular velocity fluctuation and the phase information of the detection gear, the driving means of The angular velocity fluctuation of each image carrier is detected by adjusting and controlling the speed, or by reading a pattern image formed by each image carrier and transferred to the carrier, and engaged with the image carrier. The phase difference between the gears is detected, and the phase and speed of the driving unit are adjusted and controlled based on the detected angular velocity fluctuation and the phase information of the detected gear, or the transfer is performed by forming each image carrier. The angular velocity fluctuation of each image carrier is detected by reading the pattern image transferred to the body, and the phase difference of each gear engaged with the image carrier is detected, and the detected angular velocity fluctuation and detection are performed. By adjusting and controlling the start timing of the driving means based on the vehicle phase information, the number of corrections by reading the pattern image is reduced, and the rotational phase shift of each image carrier is easily corrected, and a relative phase shift is performed. An object of the present invention is to provide a color image forming apparatus capable of reducing a color shift or a variation in angular velocity and a color shift correcting method for the color image forming apparatus.

[0009]

According to a first aspect of the present invention, a plurality of image carriers are arranged in parallel, and a plurality of driving units are driven to rotate by engaging a gear that reduces the speed by one stage with each image carrier. A color image forming apparatus comprising means for forming a color image by sequentially superimposing and transferring a color image formed on each image carrier onto a recording medium conveyed by an endlessly moving conveyance body,
First detecting means (corresponding to the detecting unit 44 shown in FIG. 3) for detecting a change in angular velocity of each image carrier by reading a pattern image formed by each image carrier and transferred to the carrier; Second detecting means (corresponding to the sensor 41 shown in FIG. 3) for detecting the phase difference between the gears engaged with each image carrier, angular velocity fluctuation detected by the first detecting means, and Control means for adjusting and controlling the phase of the drive means based on the phase information of the gears detected by the detection means (speed unevenness detection unit 100, shaft phase detection unit 101, calculation unit 102, motor control unit shown in FIG. 3) 103 etc.).

According to a second aspect of the present invention, a plurality of image carriers are arranged in parallel, and a plurality of driving means for rotating and driving each image carrier by engaging a gear which reduces the speed by one stage is provided. A color image forming apparatus for forming a color image by successively superimposing and transferring a color image formed on an image carrier onto a recording medium conveyed by an endlessly moving carrier, wherein the color image is formed by each image carrier. First detecting means (corresponding to the detecting unit 44 shown in FIG. 3) for detecting a change in angular velocity of each image carrier by reading a pattern image transferred to the carrier, and being engaged with the image carrier. Second to detect phase difference of each gear
3 (corresponding to the sensor 41 shown in FIG. 3), the angular velocity fluctuation detected by the first detecting means, and the phase information of the gear detected by the second detecting means. Control means for adjusting and controlling the speed (FIG. 3
(Corresponding to the speed unevenness detection unit 100, the shaft phase detection unit 101, the calculation unit 102, the motor control unit 103, etc.) shown in FIG.

According to a third aspect of the present invention, a plurality of image carriers are arranged in parallel, and a plurality of driving means for rotating and driving each image carrier by engaging a gear which reduces the speed by one stage is provided. A color image forming apparatus for forming a color image by successively superimposing and transferring a color image formed on an image carrier onto a recording medium conveyed by an endlessly moving carrier, wherein the color image is formed by each image carrier. First detecting means (corresponding to the detecting unit 44 shown in FIG. 3) for detecting a change in angular velocity of each image carrier by reading a pattern image transferred to the carrier, and engaged with each image carrier. Second detecting means (corresponding to the sensor 41 shown in FIG. 3) for detecting the phase difference between the gears, the angular velocity fluctuation detected by the first detecting means, and the angular velocity fluctuation detected by the second detecting means. Based on the phase information of the gear, the driving hand Control means for adjusting and controlling the phase and speed of those having a (speed variation detecting unit 100 shown in FIG. 3, the shaft phase detecting unit 101, calculation unit 102, corresponding to the motor control unit 103, etc.).

According to a fourth aspect of the present invention, a plurality of image carriers are arranged in parallel, and a plurality of drive means for rotating and driving each image carrier by engaging a gear which reduces the speed by one stage is provided. A color image forming apparatus for forming a color image by sequentially superimposing and transferring a color image formed on an image carrier onto a recording medium conveyed by a carrier that moves endlessly, wherein the color image forming apparatus is formed by each of the image carriers. First detecting means for detecting a change in the angular velocity of each image carrier by reading a pattern image transferred to the carrier, and detecting a phase difference between each gear engaged with each image carrier. Based on second detection means (corresponding to the sensor 41 shown in FIG. 3), the angular velocity fluctuation detected by the first detection means, and the phase information of the gear detected by the second detection means, the driving Adjust the start timing of the means Control to control unit (speed variation detecting unit 100 shown in FIG. 3, the shaft phase detecting unit 101, arithmetic unit 10
2, the motor control unit 103, etc.).

According to a fifth aspect of the present invention, the control means includes means for detecting each image carrier detected by the first detecting means based on phase information of each gear detected by the second detecting means. The phase of the driving means for each color is adjusted so as to reduce the phase difference of the angular velocity fluctuation.

In a sixth aspect of the present invention, the control means adjusts the phase of the driving means for each color so as to reduce the relative difference between the angular velocities of the image carriers detected by the first detecting means. Is what you do.

According to a seventh aspect of the present invention, a plurality of image carriers are arranged in parallel, and a plurality of driving means for rotating the image carriers by engaging a one-stage reduction gear with each image carrier is provided. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image formed on an image carrier onto a recording medium conveyed by an endlessly moving carrier, comprising: A first detection step (step (9) shown in FIG. 8) for detecting a change in angular velocity of each image carrier by reading a pattern image formed by a body and transferred to the carrier; A second detection step (steps (5) and (6) shown in FIG. 8) for detecting a phase difference between the engaged gears, an angular velocity change detected by the first detection step, and the second detection step. Gear phase information detected by the Hazuki control step of adjusting and controlling the phase of said driving means (step shown in FIG. 8 (10),
(11)).

According to an eighth aspect of the present invention, a plurality of image carriers are arranged side by side, and a plurality of driving means for rotating and driving each image carrier by engaging a gear which reduces the speed by one stage are provided. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image formed on an image carrier onto a recording medium conveyed by an endlessly moving conveyance body, the method comprising: A first detecting step (step (3) shown in FIG. 8) of detecting a change in angular velocity of each image carrier by reading a pattern image formed by the carrier and transferred to the carrier; A second detection step (steps (5) and (6) shown in FIG. 8) for detecting a phase difference between the gears engaged with the carrier, an angular velocity change detected in the first detection step, and Of the gear detected by the second detecting step. Based on the phase information, the step shown in the control process (FIG. 8 for adjusting and controlling the speed of said drive means (1
0) and (11)).

According to a ninth aspect of the present invention, a plurality of image carriers are arranged in parallel, and a plurality of driving means are provided for driving each of the image carriers to rotate by engaging a gear that reduces the speed by one stage. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image formed on an image carrier onto a recording medium conveyed by an endlessly moving conveyance body, the method comprising: A first detecting step (step (3) shown in FIG. 8) of detecting a change in angular velocity of each image carrier by reading a pattern image formed by the carrier and transferred to the carrier; A second detection step (steps (5) and (6) shown in FIG. 8) for detecting a phase difference between the gears engaged with the carrier, an angular velocity change detected in the first detection step, and Of the gear detected by the second detecting means. Based on the phase information, (step shown in FIG. 8 (10), (11)) control step of adjusting and controlling the phase and speed of the driving means is one having a.

According to a tenth aspect of the present invention, a plurality of image carriers are arranged in parallel, and a plurality of drive means for rotating and driving each image carrier by engaging a gear which reduces the speed by one stage is provided. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image formed on an image carrier onto a recording medium conveyed by an endlessly moving conveyance body, the method comprising: A first detecting step (step (3) shown in FIG. 8) of detecting a change in angular velocity of each image carrier by reading a pattern image formed by the carrier and transferred to the carrier; A second detection step (steps (5) and (6) shown in FIG. 8) for detecting a phase difference between the gears engaged with the carrier, an angular velocity change detected in the first detection step, and Gears detected by the second detection step Based on the phase information, (step shown in FIG. 8 (10), (11)) control step of adjusting and controlling the start timing of the driving means is one having a.

According to an eleventh aspect of the present invention, in the control step, each image carrier detected in the first detecting step is based on phase information of each gear detected in the second detecting step. The phase of the driving means for each color is adjusted so as to reduce the phase difference of the angular velocity fluctuation.

In a twelfth aspect according to the present invention, in the control step, the phase of the driving means for each color is adjusted so as to reduce the relative difference between the angular velocities of the respective image carriers detected in the first detecting step. Is what you do.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a cross-sectional view illustrating the structure of an image forming apparatus according to a first embodiment of the present invention. Four electrophotographic photosensitive drums 1y, 1m, 1c, and 1k for yellow (Y), magenta (M), cyan (C), and black (Bk), which serve as the formed image carriers (hereinafter, referred to as photosensitive drum 1). ) Is provided. Hereinafter, the configuration and operation will be described. FIG. 2 is a cross-sectional view for explaining the shaft engaging configuration of the photosensitive drum shown in FIG. 1, and the same components as those in FIG. 1 are denoted by the same reference numerals.

In FIG. 1, a transfer belt 2 serving as a transfer material carrier for adsorbing and carrying the transfer material S by electrostatic attraction is disposed opposite to each photosensitive drum 1. Each of the photosensitive drums 1 is fixed to a drum shaft 1a serving as a point shaft of the photosensitive drum. As shown in detail in FIG. 2 described later, a coupling 36 serving as a first engagement member and the coupling 36 Rotational driving force is transmitted from a drive motor (not shown) serving as a drive source to a gear 31 of a coupling B serving as a second engagement member that is engaged with and connected to the gear B, and is rotated in the direction of an arrow shown in FIG. Around).

The primary chargers 3y, 3m, 3c, 3 serving as charging means for uniformly charging the surface of the photosensitive drum 1 are arranged around each photosensitive drum 1 in order from the upstream side in the rotation direction.
k (hereinafter simply referred to as a primary charger 3), an exposure unit 4y for irradiating a laser beam on the surface of the photosensitive drum 1 uniformly charged by the primary charger 3 based on image information to form an electrostatic latent image. , 4m, 4c, 4k (hereinafter simply referred to as exposure means 4).
Has been arranged.

Further, developing means 5y, 5m, 5c, and 5k (hereinafter, referred to as developing means) for adhering toner of each color to the surface of the photosensitive drum 1 on which the electrostatic latent image is formed to visualize the toner image.
Cleaning means 6y, 6 for removing toner remaining on the surface of the photosensitive drum 1 after transfer.
m, 6c and 6k (hereinafter simply referred to as cleaning means 6) are arranged.

Photosensitive drum 1, primary charger 3, developing means 5
The cleaning means 6 is configured to be detachable from the main unit A as process cartridges 7y, 7m, 7c, and 7k (hereinafter, simply referred to as process cartridges 7) integrally formed as a cartridge.

A transfer means for transferring a toner image formed on the surface of the photosensitive drum 1 to a transfer material S carried and carried by the carrying belt 2 with the carrying belt 2 interposed therebetween at a position opposed to each photosensitive drum 1. Transfer rollers 8y, 8m,
8c and 8k (hereinafter, simply referred to as transfer rollers 8) are provided.

The photosensitive drum 1 serving as an image carrier is formed by applying an organic photoconductive layer (OPC) to an outer peripheral surface of an aluminum cylinder. The photosensitive drum 1 is rotatably instructed at both ends by a flange, and is driven to rotate counterclockwise as shown in FIG. 1 by transmitting a driving force from a driving motor (not shown) to one end. .

The primary charger 3 is a conductive roller formed in the shape of a roller. The roller is brought into contact with the surface of the photosensitive drum 1 and, at the same time, a charging bias voltage is applied by a power supply (not shown) to thereby charge the photosensitive drum. This is for uniformly charging the surface of the drum 1. The exposure means 4 has a polygon mirror, and this polygon mirror is irradiated with image light corresponding to an image signal from a laser diode (not shown).

The developing means 5 includes toner storage sections 9y, 9m, 9c, 9k (hereinafter simply referred to as toner storage sections) storing toners of yellow (Y), magenta (M), cyan (C), and black (Bk). Unit 9), which is adjacent to the surface of the photosensitive drum 1, is driven to rotate by a drive unit (not shown), and is applied with a developing bias voltage from a developing bias power source to thereby develop rollers 10y, 10m, 10c, 10
k (hereinafter simply referred to as developing roller 10).

The transfer roller 8 disposed inside the conveyor belt 2 is opposed to the four photosensitive drums 1 and contacts the conveyor belt 2. The transfer roller 8 is connected to a transfer bias power supply (not shown), and a positive charge is applied from the transfer roller 8 to the transfer material S via the transport belt 2. In S, the negative color toner images on the surface of the photosensitive drum 1 are sequentially transferred to form a color image.

A transfer roller S made of paper, synthetic resin, or the like, which is accommodated in a feed cassette 11 provided at a lower portion of the apparatus main body A, is a pickup roller 1 which rotates intermittently in a half-moon shape.
2, the sheets are separated one by one by a pair of retard rollers 13 and sent to a pair of registration rollers 14.

The transfer material S sent out at a predetermined timing by the pair of registration rollers 14 is held between the photosensitive drum 1 serving as an image forming means and the transfer roller 8 while being electrostatically attracted and carried by the conveyor belt 2. After a toner image formed on the surface of each photosensitive drum 1 is sequentially transferred to a transfer position and a color image is recorded, a heating roller 15a that is driven and rotated, and a pressure roller that is driven to rotate by pressing against the heated roller 15a After the toner image is heated and pressurized when passing through the fixing means 15 having the toner image 15b and the toner image is permanently fixed, the toner image is discharged by a discharge roller pair 16 onto a discharge tray 17 provided at an upper portion of the apparatus main assembly A. .

When forming images on both ends of the transfer material S, the toner image on the first surface is fixed by the fixing means 15 as described above, and then the transfer material S is once discharged by the discharge roller pair 16. When the rear end of the transfer material S reaches a predetermined position, the discharge roller pair 16 is reversed to guide the transfer material S to the double-sided conveyance path 18.

The transfer material S guided to the two-sided conveying path 18 is nipped by a pair of skew feeding rollers 19 disposed on the front side of the apparatus main body A and is conveyed vertically downward.
The toner image is conveyed by a U-turn, turned over, and sent again to the registration roller pair 14 to form a toner image on the second surface in the same manner as described above. Then, the toner image is fixed by the fixing unit 15 and discharged by the discharge roller pair 16. 17 is discharged.

Similarly, the transfer material S placed on the manual feed tray 21 is separated and fed one by one by the cooperation of the feed roller 22 and the separation pad 23 pressed against the feed roller 22. The toner image is conveyed by the conveying roller pair 24 and sent to the registration roller pair 14, where a toner image is formed in the same manner as described above. Then, the toner image is fixed by the fixing unit 15 and discharged onto the discharge tray 17 by the discharge roller pair 16.

The transport belt 2 stretches the transfer material transport surface.
A driving roller 25 and a driven roller 26 serving as shafts, and a tension roller 2 for applying tension to the transport belt 2
The roller 7 is rotatably supported by a total of four rollers 7 and 28 and is arranged to face all the photosensitive drums 1.

The transfer belt 2 is circulated by a driving roller 25 so that the transfer material S is electrostatically attracted to the outer peripheral surface facing the photosensitive drum 1 and the transfer material S is brought into contact with the photosensitive drum 1. As a result, the transfer material S is transported to the transfer position by the transport belt 2, and the toner image on the surface of each photosensitive drum 1 is transferred.

The transfer material S is sandwiched and cooperated with the transfer belt 2 at a position on the most upstream side of the transfer belt 2 in the transfer material transfer direction and opposed to the driven roller 26.
A suction roller 29 for electrostatically adsorbing the ink is provided.

When transferring the transfer material S, the suction roller 2
By applying a bias voltage to the transfer belt 9, electrolysis is formed between the suction roller 29 and the driven roller 26, which is opposed to the suction roller 29 via the transfer belt 2, and the transfer belt 2 and the transfer material S
The dielectric polarization is generated between them to generate an electrostatic attraction force between them.

When the transfer material S is transported by the transport belt 2, the transfer material S is configured not to be peeled off from the transport belt 2 by the transport assisting member. This transport assisting member is provided on the side of the transport belt 2 that supports the transfer material S (the transport belt 2).
, And also has a function of separating the conveying belt 2 from the photosensitive drum 1.

That is, as shown in FIG. 1, the transfer material supporting surface side (outer peripheral surface side) of the transfer belt 2 as a transfer assisting member.
A plurality of transport auxiliary rollers 30 that can be driven to rotate in contact with
The transport assist roller 30 is configured to be integrally movable in the left-right direction shown in FIG. 1 by a cam mechanism (not shown).

The transfer assist roller 30 can be brought into contact with and separated from the transfer material carrying surface side of the transfer belt 2, and transfers the toner image to the transfer material S by bringing the transfer belt 2 close to the plurality of photosensitive drums 1 as shown in FIG. The transfer belt 2 is moved to a position (not shown) in which the toner image is transferred to the transfer material S by bringing the conveyor belt 2 close to only the black photosensitive drum 1k and separated from the remaining photosensitive drums 1y, 1m, 1c.

In the color image forming apparatus constructed as described above, when forming a color image, as shown in FIG. 1, the transport assist roller 30 is retracted to the left as shown in FIG. In a state in which the transfer material 2 is brought into contact with all the photosensitive drums 1 (at the position shown in FIG. 1), the transfer material S fed from the sheet cassette 11 is electrostatically attracted to the transport belt 2 and is carried and transported. The toner images of the respective colors formed on the respective photosensitive drums 1 are sequentially transferred to form color images. After being fixed by the fixing unit 15, the toner images are discharged onto a discharge tray 17.

On the other hand, when a monochrome (black and white) image is to be formed, a cam mechanism (not shown) is operated to move the transport auxiliary roller 30 to the right as shown in FIG. By pushing the conveyor belt 2 rightward as shown in FIG. 1, the transport belt 2 is separated from the photosensitive drums 1y, 1m, and 1c of the other colors except the black photosensitive drum 1k.

In this state, the black toner image formed on the photosensitive drum 1k is transferred to the transfer material S, and the fixing means 15
Is discharged onto the discharge tray 17.
Driving means such as a driving motor (not shown) serving as a driving source (not shown) for rotating each photosensitive drum 1 is disposed on the left side of the apparatus main body, and transmits the rotational driving force to the process cartridges 7 of four colors arranged substantially vertically. I do.

Each process cartridge 7 includes the photosensitive drum 1, the developing means 5, the cleaning means 6, and the like, and supplies a driving force to all of them.

Since the process cartridge 7 can be attached to and detached from the apparatus main body A independently for each color, the drive transmission unit is also arranged independently for each color in a substantially vertical direction. Although the rotational driving force is directly transmitted to the drive unit 1, another drive, for example, the drive of the developing unit 5 and the cleaning unit 6 may be transmitted in another system.

The driving force supplied to the process cartridge 7 is distributed to each element by a driving system in the process cartridge 7.

As shown in FIGS. 2 and 3, a gear 31 for rotating the photosensitive drum 1 is connected to a drive source inside the drive transmitting portion of the process cartridge 7, and the gear 31 is integrated with the gear 31. The shaft portion 32 having a sliding portion 32a that is rotatably supported by being inserted into a cylinder bearing portion 35 provided in the apparatus main body A, rotates integrally with the shaft portion 32, and An engaging portion 3 that is engaged with and coupled to a coupling 36 serving as a first engaging member fixed to a drum shaft 1 a of the drum 1 and that transmits a rotational driving force of the photosensitive drum 1.
3 and a coupling B as a second engaging member in which a positioning hole 34 capable of fitting and supporting the drum shaft 1a of the photosensitive drum 1 is integrally formed of resin or the like.

A coupling B rotatably supported by the cylinder bearing portion 35 and movably in the direction of the rotation axis.
One end is urged in the direction of the photosensitive drum 1 side (the right side shown in FIG. 2) by a leaf spring 37 serving as urging means attached to the apparatus main body A.

A coupling 36 which rotates integrally with the drum shaft 1a is fixed to the drum shaft 1a using a parallel pin 1b, and the drum shaft 1a is accurately positioned on the apparatus main body A via a bearing portion 38. In this state, it is rotatably supported.

A non-drive-side coupling 36 serving as a first engagement member is fixed to the end of the drum shaft 1a, and is engaged with a drive-side coupling B serving as a second engagement member to generate a rotational driving force. Is transmitted.

FIG. 3 is a diagram for explaining a drum drive control configuration in the image forming apparatus according to the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals.

In FIG. 3, gears 31y, 31m, 31c, and 31k (hereinafter, referred to as motors 41) that engage with the photosensitive drum 1 by motors 41y, 41m, 41c, and 41k (hereinafter, referred to as motors 41) provided exclusively for the respective photosensitive drums 1. , Gear 3
After that, the photosensitive drum 1 is driven.

The gear 31 is provided with targets 42y, 42m, 42c and 42k (hereinafter referred to as targets 42) for detecting the phase, and optical or magnetic detection devices 43y, 43m, 43c and 43k ( The phase signal can be detected once per rotation by the detection device 43).

Further, a detection unit 44 is provided so as to face the conveyor belt 2, and an image on the conveyor belt 2 can be optically detected.

In the image forming apparatus configured as described above, the main component of the angular velocity unevenness is only one rotation cycle of the drum, so the patterns stored on the drum at equal time intervals are transferred to the transport belt 2 and the detection unit 44 Then, when the variation component of the cumulative pattern interval is obtained by the speed unevenness detection unit 100, a sine waveform as shown in FIG. 4 is obtained. The arithmetic unit 102 and the motor control unit 103 include various CPUs and RAs.
The control unit including the M and the ROM may be integrally configured. Needless to say, the motor control unit 103 includes various motor drive drivers.

In the color image forming apparatus configured as described above, the transfer belt 2 formed by each photosensitive drum
The detection unit 44 detects the angular velocity fluctuation of each photosensitive drum by reading the pattern image transferred to the motor, and based on the detected angular velocity fluctuation, the motor control unit 103 controls the motors of the other colors except the motor 41 of the reference color. While adjusting and controlling the driving speed of the photosensitive drum 41, the detection device 43 detects the photosensitive drum 1 of the reference color.
The motor control unit 103 detects a phase difference between each of the gears engaged with the other photosensitive drums 1 and 2 based on the detected phase difference between the black gear and the other gears.
And controls the phases of the photosensitive drums 1 for the other colors except for. A specific control method will be described later.

FIG. 4 is a characteristic diagram for explaining the color misregistration state of each photosensitive drum shown in FIG. 3. In FIG. 4, black (K) to be used as a reference is different from other yellow (Y), magenta ( M) and the phase difference between the rotation of the cyan (C) drum and the uneven rotation of the drum. Note that the horizontal axis represents the distance from the front end of the image, and the vertical axis represents the amount of displacement.

Here, in order to obtain the phase relationship of the four colors, the arithmetic unit 102 manages the storage start timing of each color, forms and detects one color at a time, obtains a sine waveform, and calculates the sine waveform by the start timing interval. Processing such as correction and comparison may be performed.

In the example shown in FIG. 4, when black is used as a reference, if yellow (Y) is shifted toward the front end of the image by a distance y, the relative color shift with black can be reduced, and magenta (M) As for, the color shift relative to black can be reduced by shifting the distance m and the distance c for cyan (C) as described above.

However, since this phase detection requires a predetermined time, if it is performed frequently, a loss of image forming time occurs.

Therefore, the shaft phase information is normally detected by the shaft phase detecting section 101 using the detecting device 43 for detecting the phase of the gear 31 for rotating the photosensitive drum 1 once, and the calculation is performed based on the detected information. The motor control unit 103 controls the driving of the motor 41 according to the correction data of each color calculated by the unit 102 to perform the unevenness correction control.

FIG. 5 is a characteristic diagram for explaining the rotation unevenness of each photosensitive drum shown in FIG. 3. In FIG. 5, black (K) to be used as a reference is different from other yellow (Y) and magenta (M). ), Cyan (C) and the rotation difference of the drum.

In FIG. 5, c ′ indicates the time for determining the motor start timing for canceling the color misregistration amount in the reference color black and cyan drums shown in FIG. 4, and m ′ indicates the time in FIG. The time for determining the rotation speed of the motor for canceling the amount of color misregistration in the reference color black and magenta drums is shown, and y ′ is the value in the reference color black and yellow color drums shown in FIG. The time for determining the rotation speed of the motor for canceling the color shift amount is shown.

The motor control unit 103 sets the photosensitive drum 1 to 1
Based on the output of the detection device 43 for each color that detects the phase of the gear 31 to be rotated, the calculation unit 102 calculates the yellow (Y),
The rotation speed of the motor 41 for each color is adjusted in accordance with the times c ′, m ′, and y ′ for determining the position shift correction for magenta (M) and cyan (C). Specifically, when the phase waveform of the detection device 43 is as shown in FIG. 5, the distance y shown in FIG.
The phase of the Y gear 31y is controlled so that the yellow motor 41y is started earlier for a considerable time y 'to reduce the relative color shift between black and yellow.

Similarly, the motor control unit 103 controls the magenta motor 41 for a time m ′ corresponding to the distance m shown in FIG.
m, the phase of the M gear 31m is controlled so as to reduce the relative color shift between the black color and the magenta color, and for the cyan color for the time c 'corresponding to the distance c shown in FIG. The movement of the C-color gear 31c is controlled so that the motor 41c is started earlier to reduce the relative color shift between black and cyan.

As a result, in the rotation unevenness state of the photosensitive drum 1 shown in FIG. 3, as shown in FIG. 6, the amount of color misregistration can be reduced to half or less as compared with the state shown in FIG. .

FIG. 6 is a characteristic diagram for explaining the color misregistration state of each photosensitive drum shown in FIG. 3. In FIG. 6, black (K) to be used as a reference is different from other yellow (Y) and magenta ( M) and the phase difference between the rotation of the cyan (C) drum and the uneven rotation of the drum. Note that the horizontal axis represents the distance from the front end of the image, and the vertical axis represents the amount of displacement.

When the motor 41 is configured to be capable of variable speed control, the motor control unit 103 controls each color in accordance with the correction data calculated by the calculation unit 102 based on the phase and amplitude information shown in FIG. Like offsetting the speed unevenness of
That is, by performing speed control so that the phase is opposite to the phase shown in FIG. 4, the accuracy of the speed unevenness can be improved as shown in FIG. It is also possible to combine both phase control and speed control.

FIG. 8 is a flowchart showing an example of the procedure for correcting the positional deviation in the image forming apparatus according to the present invention. Note that (1) to (11) indicate each step.

First, it is determined whether or not the speed unevenness correction using the sensor 44 has been completed (1). If it is determined that the correction has not been completed, a pattern for detecting a displacement (not shown) on each photosensitive drum 1 is determined. It waits for an image to be formed (2), and waits for the detection unit 44 to read the pattern image formed and transferred onto the conveyor belt 2 (3). A speed unevenness correction value is calculated by the detection unit 100 and the calculation unit 102 (4), and the motor control unit 103 rotates the photosensitive drums 1 according to the speed unevenness correction value calculated by the calculation unit 102. Correction is started (5).

When the speed unevenness correction is completed (6), each color image data generated based on the image information input through an interface (not shown) is generated.
Each laser unit is modulated and driven based on the generated color image data to form an image for each image forming station (7). When the image formation is completed (8), the process returns.

On the other hand, if it is determined in step (1) that the process for reading the pattern transferred to the belt and correcting the speed unevenness has been completed, the shaft phase shift state (gear 41) (9), the arithmetic unit 102 calculates angular velocity unevenness from the detected shaft phase shift state (10), and calculates the motor speed according to the calculated angular speed unevenness. The control unit 103 sets the black image forming station as a reference.
The speeds of the photosensitive drums 1 of the other colors are set at time c ', shown in FIG.
The speed of the motor 41 is adjusted so as to cancel out m 'and y' (11), and the process proceeds to step (7) to start image formation.

[Second Embodiment] FIG. 9 is a sectional view showing an example of an image forming apparatus according to a second embodiment of the present invention.
This corresponds to a color image forming apparatus in which photosensitive drums of each color are horizontally arranged. The same components as those in FIG. 1 are denoted by the same reference numerals.

In FIG. 9, the toner image formed on the surface of the photosensitive drum 1 facing the photosensitive drum 1 serving as a plurality of image carriers arranged side by side in the horizontal direction is transferred to the intermediate transfer belt 51.
Is primary-transferred. Intermediate transfer belt 5 serving as an intermediate transfer member
1 is stretched by a driving roller 52 and driven rollers 53 and 54, and a secondary transfer member 55 is disposed at a position facing the driven roller 54 with the intermediate transfer belt 51 interposed therebetween.

The toner images formed on the respective photosensitive drums 1 in the same manner as in the first embodiment are transferred to transfer means 56y, 56
The primary transfer is performed on the intermediate transfer belt 51 by the action of m, 56c, and 56k (hereinafter, referred to as transfer means 56).

On the other hand, the transfer material S fed out from the paper feed cassette 11 by the pickup roller 12 is separated and fed one by one by a separating means (not shown), and then sent to the registration roller pair 14 by the transport roller pair 57. The toner image is transferred between the intermediate transfer belt 51 and the secondary transfer roller 55 at a predetermined timing by the registration roller pair 14, and the toner image primarily transferred to the intermediate transfer belt 51 by the operation of the secondary transfer roller 55 is subjected to the secondary transfer. Is done.

Then, the transfer material S to which the toner image has been transferred
After the toner image is fixed by the fixing unit 15, the toner image is conveyed by the discharge roller pair 58 and discharged onto the discharge tray 17 provided at the upper part of the apparatus main body A.

Also in this embodiment, the same effect can be expected by applying the motor control configuration shown in FIG. 3 of the first embodiment.

Hereinafter, the configuration of a data processing program readable by an image processing system to which the image forming apparatus according to the present invention can be applied will be described with reference to a memory map shown in FIG.

FIG. 10 is a diagram illustrating a memory map of a storage medium for storing various data processing programs that can be read by an image processing system to which the image forming apparatus according to the present invention can be applied.

Although not shown, information for managing a group of programs stored in the storage medium, for example, version information, a creator and the like are also stored, and information dependent on the OS or the like on the program reading side, for example, a program is stored in the storage medium. An icon or the like for identification display may also be stored.

Further, data dependent on various programs is also managed in the directory. In addition, a program for installing various programs on a computer or a program for decompressing a program to be installed when the program to be installed is compressed may be stored.

The functions shown in FIG. 8 in this embodiment may be performed by a host computer by a program installed from the outside. In this case, the present invention is applied even when a group of information including a program is supplied to the output device from a storage medium such as a CD-ROM, a flash memory, or an FD, or from an external storage medium via a network. Things.

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 and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the 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 (registered trademark) disk, hard disk, optical disk, magneto-optical disk, and C
D-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, EEPROM, etc. 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.

[0091]

As described above, according to the present invention, a plurality of image carriers are arranged side by side, and a plurality of driving means for rotating and driving each image carrier by engaging a gear which reduces the speed by one stage. A color image forming apparatus that sequentially overlaps and transfers a color image formed on each image carrier onto a recording medium conveyed by a conveyer that moves endlessly to form a color image,
The angular velocity fluctuation of each image carrier is detected by reading the pattern image formed by each image carrier and transferred to the carrier, and the phase difference of each gear engaged with the image carrier is detected. Since the phase of the driving means is adjusted and controlled based on the detected angular velocity fluctuation and the phase information of the detection gear, the number of corrections by reading the pattern image is reduced, and the rotational phase shift of each image carrier is simplified. And it is possible to reduce the relative color shift or angular velocity fluctuation.

Further, a plurality of image carriers are arranged side by side, and a plurality of driving means for rotating and driving each image carrier by engaging a gear for decelerating by one stage is provided, and the color formed on each image carrier is provided. In a color image forming apparatus that forms a color image by sequentially superimposing and transferring an image on a recording medium conveyed by an endlessly moving conveyance body, a pattern image formed by each image carrier and transferred to the conveyance body is read. By detecting the angular velocity variation of each image carrier, and by detecting the phase difference of each gear engaged with the image carrier, the detected angular velocity variation,
And the speed of the driving means is adjusted and controlled based on the phase information of the detection gear, so that the number of corrections by reading the pattern image is reduced, and the rotational phase shift of each image carrier is easily corrected, and There is an effect that color shift or angular velocity fluctuation can be reduced.

Further, a plurality of image carriers are arranged in parallel, and a plurality of drive means are provided for driving each of the image carriers to rotate by engaging a gear for decelerating by one stage. In a color image forming apparatus that forms a color image by sequentially superimposing and transferring an image on a recording medium conveyed by an endlessly moving conveyance body, a pattern image formed by each image carrier and transferred to the conveyance body is read. By detecting the angular velocity variation of each image carrier, and by detecting the phase difference of each gear engaged with the image carrier, the detected angular velocity variation,
And the phase and speed of the driving means are adjusted and controlled based on the phase information of the detection gear, so that the number of corrections by reading the pattern image is reduced, and the rotational phase shift of each image carrier is easily corrected, This has the effect of reducing typical color shift or angular velocity fluctuation.

Further, a plurality of image carriers are arranged side by side, and a plurality of driving means for rotating and driving each image carrier by engaging a gear for decelerating by one stage are provided, and a color formed on each image carrier is provided. In a color image forming apparatus that forms a color image by sequentially superimposing and transferring an image on a recording medium conveyed by an endlessly moving conveyance body, a pattern image formed by each image carrier and transferred to the conveyance body is read. Detecting the angular velocity fluctuation of each image carrier, and detecting the phase difference of each gear engaged with the image carrier, based on the detected angular velocity fluctuation and the phase information of the detected gear, driving means The start timing of the image is adjusted and controlled, so the number of corrections by reading the pattern image is reduced, the rotational phase shift of each image carrier is easily corrected, and the relative color shift or angular velocity fluctuation is reduced. To be an effect that it is.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view illustrating a shaft engagement configuration of the photosensitive drum shown in FIG.

FIG. 3 is a diagram illustrating a drum drive control configuration in the image forming apparatus according to the present invention.

FIG. 4 is a characteristic diagram for explaining a color misregistration state of each photosensitive drum shown in FIG.

FIG. 5 is a characteristic diagram illustrating rotation unevenness of each photosensitive drum illustrated in FIG. 3;

FIG. 6 is a characteristic diagram for explaining a color misregistration state of each photosensitive drum shown in FIG.

FIG. 7 is a characteristic diagram for explaining rotation unevenness of each photosensitive drum shown in FIG. 3;

FIG. 8 is a flowchart illustrating an example of a positional deviation correction processing procedure in the image forming apparatus according to the present invention.

FIG. 9 is a cross-sectional view illustrating an example of an image forming apparatus according to a second exemplary embodiment of the present invention.

FIG. 10 is a diagram illustrating a memory map of a storage medium that stores various data processing programs that can be read by an image processing system to which the image forming apparatus according to the present invention can be applied.

Claims (12)

[Claims] 1. A plurality of image carriers are provided side by side, and a plurality of drive means are provided on each of the image carriers, and each of the image carriers has a plurality of drive means for rotating and driving the image carrier by a one-stage reduction gear. A color image forming apparatus for sequentially transferring a color image on a recording medium conveyed by an endlessly moving conveyance body to form a color image, wherein the color image is formed by each of the image carriers and transferred to the conveyance body. First detecting means for detecting a change in angular velocity of each image carrier by reading a pattern image; second detecting means for detecting a phase difference between gears engaged with each image carrier; Control means for adjusting and controlling the phase of the drive means based on the angular velocity fluctuation detected by the first detection means and the phase information of the gear detected by the second detection means. Color image forming equipment . 2. A plurality of image carriers are arranged side by side, and a plurality of drive means for rotating and driving each image carrier by engaging a gear which reduces the speed by one stage are provided on each of the image carriers. A color image forming apparatus for sequentially transferring a color image on a recording medium conveyed by an endlessly moving conveyance body to form a color image, wherein the color image is formed by each of the image carriers and transferred to the conveyance body. First detecting means for detecting a change in angular velocity of each image carrier by reading a pattern image; second detecting means for detecting a phase difference between gears engaged with each image carrier; Control means for adjusting and controlling the speed of the driving means based on the angular velocity fluctuation detected by the first detecting means and the phase information of the gear detected by the second detecting means. Color image forming equipment . 3. A plurality of image carriers are provided side by side, and a plurality of drive means are provided on each of the image carriers, each of the image carriers having a plurality of drive means for rotating and driving the image carrier by engaging a one-stage reduction gear. A color image forming apparatus for sequentially transferring a color image on a recording medium conveyed by an endlessly moving conveyance body to form a color image, wherein the color image is formed by each of the image carriers and transferred to the conveyance body. First detecting means for detecting a change in angular velocity of each image carrier by reading a pattern image; second detecting means for detecting a phase difference between gears engaged with each image carrier; Control means for adjusting and controlling the phase and speed of the drive means based on the angular velocity fluctuation detected by the first detection means and the phase information of the gear detected by the second detection means. Color picture Image forming device. 4. A plurality of image carriers are arranged side by side, and a plurality of drive means are provided on each of the image carriers, each of the image carriers having a plurality of driving means for rotating and driving the image carrier by a one-step reduction gear. A color image forming apparatus for sequentially transferring a color image on a recording medium conveyed by an endlessly moving conveyance body to form a color image, wherein the color image is formed by each of the image carriers and transferred to the conveyance body. First detecting means for detecting a change in angular velocity of each image carrier by reading a pattern image; second detecting means for detecting a phase difference between gears engaged with each image carrier; Control means for adjusting and controlling the start timing of the driving means based on the angular velocity fluctuation detected by the first detecting means and the phase information of the gear detected by the second detecting means. Color painting Image forming device. 5. The control means reduces a phase difference in angular velocity fluctuation of each image carrier detected by the first detection means based on phase information of each gear detected by the second detection means. The color image forming apparatus according to claim 1, wherein the phase of the driving unit for each color is adjusted so as to cause the driving. 6. The apparatus according to claim 1, wherein the control unit adjusts the phase of the driving unit for each color so as to reduce the relative difference between the angular velocities of the image carriers detected by the first detecting unit. A color image forming apparatus according to any one of claims 1 to 4. 7. A plurality of image carriers are juxtaposed, and a plurality of drive means are provided on each of the image carriers, each of the image carriers having a plurality of driving means for rotating by driving a gear for one-step reduction. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image onto a recording medium conveyed by a conveyer that moves endlessly, the method comprising: A first detection step of detecting a change in angular velocity of each of the image carriers by reading a pattern image transferred to a body, and a second detection of detecting a phase difference between gears engaged with the image carriers. And a control step of adjusting and controlling the phase of the driving means based on the angular velocity fluctuation detected in the first detection step and the phase information of the gear detected in the second detection step. Characterized by color -A method for correcting a color shift of an image forming apparatus. 8. A plurality of image carriers are provided side by side, and a plurality of drive means are provided on each of the image carriers, the plurality of driving means being driven to rotate by engaging a gear which reduces the speed by one stage with each image carrier. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image onto a recording medium conveyed by a conveyer that moves endlessly, the method comprising: A first detection step of detecting a change in angular velocity of each of the image carriers by reading a pattern image transferred to a body; and a second detection step of detecting a phase difference between gears engaged with each of the image carriers. A detecting step; and a controlling step of adjusting and controlling the speed of the driving unit based on the angular velocity fluctuation detected in the first detecting step and the phase information of the gear detected in the second detecting step. Mosquito characterized by A color misregistration correction method for an image forming apparatus. 9. A plurality of image carriers are provided side by side, and a plurality of drive means are provided on each of the image carriers, the plurality of driving means being rotationally driven by engaging a gear for decelerating by one step with each image carrier. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image onto a recording medium conveyed by a conveyer that moves endlessly, the method comprising: A first detection step of detecting a change in angular velocity of each of the image carriers by reading a pattern image transferred to a body; and a second detection step of detecting a phase difference between gears engaged with each of the image carriers. A detecting step, a control step of adjusting and controlling the phase and speed of the driving means based on the angular velocity fluctuation detected by the first detecting step and the phase information of the gear detected by the second detecting means; It is special to have A color misregistration correction method for a color image forming apparatus. 10. A plurality of image carriers are arranged side by side, and a plurality of drive means are provided on each of the image carriers, the plurality of driving means being driven to rotate by engaging a gear which reduces the speed by one stage with each image carrier. A color misregistration correction method for a color image forming apparatus for forming a color image by successively superimposing and transferring a color image onto a recording medium conveyed by a conveyer that moves endlessly, the method comprising: A first detection step of detecting a change in angular velocity of each of the image carriers by reading a pattern image transferred to a body; and a second detection step of detecting a phase difference between gears engaged with each of the image carriers. A detecting step; and a control step of adjusting and controlling a start timing of the driving unit based on the angular velocity fluctuation detected in the first detecting step and the phase information of the gear detected in the second detecting step. To have A color misregistration correction method for a color image forming apparatus. 11. The control process according to claim 1, wherein the first detection is performed based on phase information of each gear detected in the second detection.
11. The color image forming apparatus according to claim 7, wherein the phase of the driving means for each color is adjusted so as to reduce the phase difference of the angular velocity fluctuation of each image carrier detected in the detecting step. A method for correcting a color shift of a device. 12. The method according to claim 1, wherein the controlling step adjusts the phase of the driving means for each color so as to reduce the relative difference between the angular velocities of the image carriers detected in the first detecting step. A color misregistration correction method for a color image forming apparatus according to any one of claims 9 to 10.