JP2000172148A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an image quality from being deteriorated, while equalizing peripheral speed of the image carrier and the traveling speed of a recording medium by respectively providing first and second generating means for generating first and second speed corresponding value, and controlling means for performing control of driving means of the image carrier in order to equalize the first and second speed corresponding value. SOLUTION: A rectangular wave WA constitutes the first speed corresponding value corresponding to peripheral speed of a photoreceptor drum, and the rectangular wave WB is the transporting speed of a transporting belt, that is, the second speed corresponding value corresponding to shifting speed of a recording medium. Moreover, a wave shape forming device 41 constitutes a first producing means, and the reference space generating device 42 constitutes, the second producing means. The angular speed ω1 of a motor 45 is controlled so that a phase of the rectangular wave WA matches with the rectangular wave WB. Thus, the peripheral speed of the photoreceptor drum and the shifting speed of the recording medium can be equalized, therefore the toner image transferred on the recording medium is prevented from the occurrence of disturbance, slippage, or the like. Accordingly, the image quality is free from deterioration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a printer and a copying machine.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer or a copying machine, an electrostatic latent image is written on a surface of a photosensitive drum as an image carrier by an optical writing device, and the electrostatic latent image is developed by a developing device. To form a toner image, transfer the toner image to a recording medium such as paper by a transfer device, and fix the toner image transferred to the recording medium by a fixing device to form an image. I have.

The recording medium is unwound from a paper cassette or the like, and sent to a transfer section between the photosensitive drum and a transfer device by a transfer device such as a transfer roller or a transfer belt.
After the transfer of the toner image in the transfer section, the toner image is sent to a fixing device. By the way, in the transfer section,
Since the position of the toner image formed on the photosensitive drum and the position of the recording medium need to be accurately matched, the timing of sending the recording medium to the transfer unit by the registration roller is determined, and the circumference of the photosensitive drum is determined. The transport speed of the transport device is set such that the speed is equal to the moving speed of the recording medium. In this case, since the distance from the registration roller to the transfer unit, the diameter of the photosensitive drum, and the like have constant values determined in the design stage of the image forming apparatus, the peripheral speed of the photosensitive drum, The transfer speed and the like of the transfer device are determined in advance.

[0004]

However, in the conventional image forming apparatus, the peripheral speed of the photosensitive drum and the moving speed of the recording medium are not exactly equal. This is because the diameter of the photoconductor drum is slightly different from the design value due to manufacturing errors, the cross-sectional shape of the photoconductor drum is not exactly a perfect circle, and the rotation axis is slightly shifted from the center of the photoconductor drum. The peripheral speed of the photoconductor drum is not strictly constant due to slipping or rattling in the drive system of the photoconductor drum, and the peripheral speed varies locally.

Similarly, when the transport speed of the transport device is not constant due to a manufacturing error, the moving speed of the recording medium and the peripheral speed of the photosensitive drum are not equal. If the peripheral speed of the photosensitive drum and the moving speed of the recording medium are not equal, the surface of the photosensitive drum and the surface of the recording medium rub against each other at the transfer section, and are transferred to the recording medium. The toner image is disturbed, and the image quality is reduced.

[0006] Since the difference between the peripheral speed of the photosensitive drum and the moving speed of the recording medium is small, the disturbance of the toner image is also small and usually inconspicuous, but when high image quality is required, Also, a slight disturbance of the toner image is a problem. When a color image is formed, yellow,
Since toner images of each color, such as magenta, cyan, and black, are superimposed and transferred to the same location on the recording medium, if the toner images of each color are displaced during the transfer, the image quality deteriorates.

The present invention solves the above-mentioned problems of the conventional image forming apparatus, and makes it possible to make the peripheral speed of the image carrier equal to the moving speed of the recording medium so that the image quality does not deteriorate. It is an object to provide a forming device.

[0008]

For this purpose, in an image forming apparatus according to the present invention, an image carrier, an optical writing device for writing an electrostatic latent image on the surface of the image carrier, and the electrostatic latent image Developing device for developing the toner image to form a toner image, a transfer device for transferring the toner image to a recording medium, and first generating means for generating a first speed corresponding value corresponding to a peripheral speed of the image carrier A second generating means for generating a second speed corresponding value corresponding to the moving speed of the recording medium; and a driving means for driving the image carrier for equalizing the first and second speed corresponding values. And control means for performing control.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this case, a color image forming apparatus for forming a color image will be described. FIG. 1 is a perspective view of a photosensitive drum according to a first embodiment of the present invention, FIG. 2 is a conceptual diagram of an image forming apparatus according to the first embodiment of the present invention, and FIG. 3 is a first embodiment of the present invention. It is a principal part enlarged view of the magnetic pattern tape in a form.

In the figure, 11 is a paper guide for guiding a recording medium 13 such as paper, 12 is a registration roller for transporting the recording medium 13, 14 is a driving roller rotated at a constant speed, and 15 is a driving roller. A transport belt that travels by rotating and transports the recording medium 13, 16 is a driven roller, 17 is a fixing guide, 20 is a fixing device that fixes the toner image transferred to the recording medium 13,
1 is a pressure roller, 22 is a heating roller, and 23 is a heater disposed in the heating roller 22 for heating the heating roller 22.

Reference numeral 24 denotes an image forming engine for forming toner images of respective colors of yellow (Y), magenta (M), cyan (C) and black (Bk) as shown in FIG. Four image forming engines 24
Are arranged in tandem in the transport direction of the recording medium 13.
Here, since the structure of each image forming engine 24 is basically the same, only the image forming engine 24 for forming a yellow toner image will be described, and the image forming engine 24 for forming magenta, cyan and black toner images will be described. Description of the image forming engine 24 is omitted.

Reference numeral 25 denotes a photosensitive drum as an image carrier having a photosensitive layer formed of a photoconductive material on the surface. The photoconductor drum 25 has a radius r1 and is rotated at an angular velocity ω1 by a motor (not shown) as driving means. As the photoconductive material, any of an organic photoconductive material and an inorganic photoconductive material can be used, and a negative type photoconductive material and a positive type photoconductive material can also be used. . Further, as the photoreceptor layer, a photoreceptor layer having a single layer, a photoreceptor layer having a charge generation layer and a charge transport layer, and the like can be used.

Reference numeral 26 denotes a static eliminator for removing charges remaining on the photosensitive layer. As the static eliminator 26,
A static eliminator of a static elimination lamp type, a static eliminator of a discharge wire type, a static eliminator of a charging roller type, and the like can be used. Reference numeral 27 denotes a charger for uniformly charging the photoconductor layer. As the charger 27, a discharge wire charger, a charging roller charger, or the like can be used. Reference numeral 28 denotes an optical writing device that irradiates light to write an electrostatic latent image on the photoconductor layer. The optical writing device 28 includes a laser scanner type optical writing device and an LED array type light writing device. A writing device, a liquid crystal shutter type optical writing device, or the like can be used.

Reference numeral 29 denotes a developing device which contains toner and develops the electrostatic latent image to form a toner image. The developing device 29 includes a magnetic brush type developing device and a bias voltage applying type developing device. An apparatus or the like can be used. In addition,
As the toner, a one-component toner, a two-component toner, a toner containing a coloring agent and a charging agent, a toner containing a magnetic agent, a microcapsule toner, a toner containing various components, and the like can be used. . As a development method, a method of attaching toner to a portion of the photoconductor layer irradiated with light is used, but a method of attaching toner to a portion of the photoconductor layer not irradiated with light is used. Can also.

Reference numeral 30 denotes a transfer device for transferring the toner image on the photosensitive drum 25 to the recording medium 13. As the transfer device 30, a pressure type transfer device, a thermal type transfer device, and an electrostatic force are used. For example, a transfer device of a discharge wire type, a transfer device of a charging roller type, or the like can be used. In addition,
A transfer section is formed between the photosensitive drum 25 and the transfer device 30.

Reference numeral 31 denotes a magnetic pattern tape; and 32, a pickup for detecting a change in the magnetic pattern of the magnetic pattern tape 31. The magnetic pattern tape 31
Are adhered to the surface of the end portion of the photoreceptor drum 25 not related to the formation of an image, and as shown in FIG. 3, for example, S formed alternately every 1/1200 [inch].
It has a magnetic pattern with poles and north poles. The pickup 32 is composed of a coil disposed in close proximity to the magnetic pattern tape 31 so as to face the lowermost end at the end of the photosensitive drum 25, and induces an alternating magnetic field generated by a change in the magnetic pattern. By power action,
An AC voltage is generated as a sensor output corresponding to the peripheral speed (rxw) of the photosensitive drum 25. Therefore, the photosensitive drum 2 in the transfer section is picked up by the pickup 32.
5 can be detected.

Next, the operation of the image forming apparatus having the above configuration will be described. When the recording medium 13 is fed through the paper guide 11, the rotation of the registration roller 12 is started by an instruction from a control unit (not shown), and the recording medium 13 is transferred to a transfer unit of an image forming engine 24 for forming a yellow toner image. Sent to In this case, the transport belt 15 transports the recording medium 13 at a constant transport speed, and the recording medium 13 moves the transfer unit at a moving speed equal to the transport speed.

On the other hand, the image forming engine 24 starts an operation for forming a toner image in conjunction with the start of rotation of the registration roller 12. That is, the motor is driven, the rotation of the photosensitive drum 25 is started, and the surface of the photosensitive drum 25 is uniformly and uniformly charged by the charger 27. Subsequently, an electrostatic latent image is written on the photosensitive layer on the photosensitive drum 25 by the optical writing device 28. Next, the developing device 29 applies yellow toner to the surface of the electrostatic latent image to perform development, and a yellow toner image is formed on the photosensitive drum 25.

The toner image is transferred to the photosensitive drum 25
The recording medium 13 is transferred to the transfer unit by the transfer device 30 with the rotation of. Here, the rotation of the photosensitive drum 25 is started at the timing when the toner image reaches the transfer section when the recording medium 13 reaches the transfer section, and the peripheral speed of the photosensitive drum 25 in the transfer section and the recording medium 1
The angular velocity ω1 of the motor is controlled so that the moving speed of the motor 3 becomes equal to that of the motor.

The optical writing device 28 scans light in the axial direction (main scanning direction) of the photosensitive drum 25, and
5, an electrostatic latent image is written on the surface. Note that the size of the image is set according to the size of the recording medium 13. In this manner, the recording medium 13 on which the yellow toner image has been transferred
Is transported by the transport belt 15 and sent to a transfer section of the image forming engine 24 for forming a magenta toner image.

The operation of the image forming engine 24 for forming each of the magenta, cyan and black toner images is basically the same. The description of the operation of the image forming engine 24 will be omitted. When the yellow, magenta, cyan, and black toner images are transferred onto the recording medium 13 in this manner, the recording medium 13 is separated from the transport belt 15 by the fixing guide 17 and sent to the fixing device 20. .

In the fixing device 20, the recording medium 13
Is transported while being sandwiched between the pressure roller 21 and the heating roller 22, pressed by the pressure roller 21, and heated by the heating roller 22. As a result, the toner that forms the toner image of each color on the recording medium 13 is melted and adheres to the recording medium 13. The recording medium 13 on which fixing has been performed in this manner is carried out of the image forming apparatus.

Next, a drive unit of a motor for rotating the photosensitive drum 25 will be described. FIG. 4 is a block diagram of a motor driving unit according to the first embodiment of the present invention, FIG. 5 is a time chart showing operation of the motor driving unit according to the first embodiment of the present invention, and FIG. FIG. 3 is a diagram illustrating a driving unit of each motor of four image forming engines according to the first embodiment.

[0024] In FIG, 41 is rectangular (Ku) shapes the AC voltage V _A of the pickup 32 square wave W waveform shaper for generating _A, 42 is as stable reference waveform having a constant period as a reference reference interval generator for generating a rectangular wave W _B, 43 is a phase comparator for comparing the phase and square wave W _B of the rectangular wave W _a phase, 44 when receiving a start signal, the phase comparator 43 A motor drive circuit as a control unit that drives the motor 45 based on the output F to rotate the photosensitive drum 25 (FIG. 2).

The pickup 32 generates an AC voltage V _A by an induced electromotive force of an alternating magnetic field generated with a change in the magnetic pattern of the magnetic pattern tape 31 (FIG. 3).
, The AC voltage _VA represents the change in the poles of the magnetic pattern. In the magnetic pattern, for example, S poles and N poles are alternately formed every 1/1200 [inch], so that the number of positive or negative peaks of the AC voltage _VA per unit time is determined. When calculated, the distance traveled by the outer peripheral surface of the photosensitive drum 25 per unit time can be calculated. For example, if the number of positive peaks of the AC voltage _VA for one second is M, the peripheral speed of the photosensitive drum 25 is M / 1200 [inch / second].

Since the cycle of the AC voltage _VA of the pickup 32 is the reciprocal of the peripheral speed of the photosensitive drum 25,
When the cycle of the AC voltage _VA becomes longer, the photosensitive drum 2
The peripheral speed of No. 5 decreases. Then, when the cycle of the AC voltage _VA is shortened, the peripheral speed of the photosensitive drum 25 is increased. The waveform shaper 41 shapes the AC voltage _VA represented by a sine curve as shown in FIG.
The rectangular wave W _A suitable for the processing in
Period of _A is equal to the period of the AC voltage V _A. Therefore, the number of leading edge per unit time square wave W _A (rising) or trailing edge (falling), the
Shows the peripheral speed of the photosensitive drum 25, the period of the rectangular wave W _A represents the inverse of the peripheral speed of the photosensitive drum 25.

On the other hand, a reference interval generator 42, the conveying speed of the conveyor belt 15, i.e., outputs a rectangular wave W _B indicating the moving speed of the recording medium 13. Accordingly, the number of leading edge or trailing edge per unit time square wave W _B indicates the moving speed of the recording medium 13, the period of the rectangular wave W _B denotes the inverse of the moving speed of the recording medium 13. As the phase comparator 43 compares the phase and square wave W _B of the rectangular wave W _A phase, indicated by the broken line in FIG. 5, a rectangular wave W _A
When the phase is advanced from the phase of the rectangular wave W _B a positive signal, the phase of the rectangular wave W _A is to generate the delays from the phase of the rectangular wave W _B a negative signal as an output F. Phase comparator 4
The absolute value of the output F of 3, rectangular wave W _A phase and a rectangular wave W _B
Is proportional to the absolute value of the difference from the phase.

[0028] By the way, the rectangular wave W _A of the phase rectangular-wave W _B
It proceeds from the phase, is that the cycle of the rectangular wave W _A is shortened, indicates that the peripheral speed of the photosensitive drum 25 becomes higher than the moving speed of the recording medium 13, on the contrary, the rectangular wave W _A phase It is but be delayed from the phase of the rectangular wave W _B, square wave W _a
Indicates that the peripheral speed of the photosensitive drum 25 becomes lower than the moving speed of the recording medium 13.

Therefore, the output F of the phase comparator 43 is input to a motor drive circuit 44, and the peripheral speed of the photosensitive drum 25 is changed by the motor drive circuit 44. In other words, immediately after receiving the start signal, the motor driving circuit 44 rotates the photosensitive drum 25 at a preset peripheral speed based on a constant value determined in the design stage of the image forming apparatus. The motor 45 is driven. When the phase comparator 43 outputs the output F to the motor driving circuit 44, the motor driving circuit 44 determines that the angular velocity of the motor 45 is lower when the output F is positive so that the peripheral speed of the photosensitive drum 25 becomes lower. ω1 is controlled. Conversely, when the output F is negative, the angular speed ω1 is controlled so that the peripheral speed of the photosensitive drum 25 is increased. Angular velocity ω of motor 45
The degree by which 1 is changed is proportional to the absolute value of the output F.

When the output F of the phase comparator 43 becomes 0 and the peripheral speed of the photosensitive drum 25 becomes equal to the moving speed of the recording medium 13, the motor drive circuit 44 controls the motor 45 to maintain the angular speed ω1. Perform control. The rotation of the photosensitive drum 25 is controlled independently in each of the image forming engines 24 for forming the respective toner images of yellow, magenta, cyan and black, but as shown in FIG. The structure of the image forming engine 24 is the same. The reference interval generator 42 and the activation signal are common to each image forming engine 24.

In the present embodiment, a color image forming apparatus provided with four image forming engines 24 for forming toner images of yellow, magenta, cyan, and black is described. In an image forming apparatus that does not form a color image, one image forming engine is provided. Note that even an image forming apparatus that forms a color image may be provided with two or three image forming engines.

In the present embodiment, the magnetic pattern tape 31 and the pickup 32 are used to detect the peripheral speed of the photosensitive drum 25, but instead of the magnetic pattern tape 31 and the pickup 32, a reflection It is also possible to use a mold slit and a reflection type photosensor or a transmission type slit and a transmission type photosensor. further,
In the present embodiment, the peripheral speed of the photoconductor drum 25 is detected to control the angular speed ω1 of the photoconductor drum 25. However, when only one image forming engine is used, the conveyance belt The moving speed of the recording medium 13 can be controlled by detecting the transport speed.

As described above, in the present embodiment,
Moves the pickup 32 in opposition to the photosensitive drum 25.
To the peripheral speed of the photosensitive drum 25 in the transfer section.
Square wave W with example number of leading edges_ADetect
Out, leading in proportion to the moving speed of the recording medium 13
Square wave W with number of edges_BSquare wave compared to
W _A, W_BSo that the square wave W_Aof
Phase and square wave W_BMotor 4 so that the phase of
5 is controlled. Note that the rectangle
Wave W_AIs the first speed corresponding to the peripheral speed of the photosensitive drum 25
The degree corresponding value is represented by a square wave W_BIs the transport speed of the transport belt 15,
That is, the second speed corresponding to the moving speed of the recording medium 13
Configure the degree correspondence value. Also, the waveform shaper 41 is a first raw
And the reference interval generator 42 constitutes a second generating means.
I do.

Therefore, due to a manufacturing error, the diameter of the photosensitive drum 25 is different from the designed value, the cross-sectional shape of the photosensitive drum 25 is not a perfect circle, or the rotation axis is shifted from the center of the photosensitive drum 25. Even if the peripheral speed of the photoconductor drum 25 is not constant due to the attachment or slipping or rattling in the drive system of the photoconductor drum 25, or the peripheral speed fluctuates locally, the photoconductor drum 25
And the moving speed of the recording medium 13 can be made equal.

As a result, the photosensitive drum 2
Since the surface of the recording medium 13 and the surface of the recording medium 13 do not rub against each other, the toner image transferred to the recording medium 13 is not disturbed or misaligned. Therefore, the image quality does not deteriorate. Next, a second embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol.

FIG. 7 is a perspective view of a photosensitive drum and a conveying belt according to a second embodiment of the present invention, and FIG. 8 is a block diagram of a motor driving unit according to the second embodiment of the present invention. In the figure, 33 is a magnetic pattern tape, 34
Is a pickup for detecting a change in the magnetic pattern of the magnetic pattern tape 33. The magnetic pattern tape 33 is adhered to the surface of the edge of the conveyor belt 15 that is not related to the formation of an image, and has a magnetic pattern of S poles and N poles alternately formed every 1/1200 [inch], for example. . The pickup 34 is composed of a coil disposed close to the magnetic pattern tape 33 so as to face the lowermost end of the photosensitive drum 25 as an image carrier, and is generated by a change in the magnetic pattern. Due to the induced electromotive force of the alternating magnetic field, an AC voltage V _C is generated as a sensor output corresponding to the transport speed of the transport belt 15 that transports the recording medium 13. Therefore, the pickup 34 can detect the transport speed of the transport belt 15 at the transfer section. In addition,
The magnetic pattern tape 33 can be bonded to the front side (outside) of the loop-shaped transport belt 15, but is preferably bonded to the back side (inside).

In order to avoid interference, the magnetic pattern tape 33 and the pickup 34
And at a position away from the pickup 32. The length of the photosensitive drum 25 in the axial direction is equal to the length of the transport belt 1.
5, the magnetic pattern tape 31 can be bonded to one end of the photosensitive drum 25, and the magnetic pattern tape 33 can be bonded to one edge of the transport belt 15. When the length of the photosensitive drum 25 in the axial direction is substantially equal to the width of the conveyor belt 15, the magnetic pattern tape 31 is adhered to one end of the photosensitive drum 25,
It is desirable that the magnetic pattern tape 33 be adhered to the other edge of the transport belt 15 that is not related to the formation of an image.

46 is the AC voltage of the pickup 34
V_CSquare wave W_CWaveform shaper.
Then, the phase comparator 43 outputs the rectangular wave W_APhase and square wave
W_COf the square wave W_APhase is a square wave W_C
If the signal is ahead of the phase of _APhase of
Is a square wave W_CIf the signal is behind the phase of
Is generated as an output F.

[0039] Then, as the phase of the rectangular wave W _C of the rectangular wave W _A match, the angular velocity of the motor 45 is controlled. Incidentally, the rectangular wave W _A first speed corresponding value corresponding to the peripheral speed of the photosensitive drum 25, the rectangular wave W _C recording medium 1
A second speed corresponding value corresponding to the moving speed of No. 3 is formed.
Further, the waveform shaper 41 constitutes a first generator, and the waveform shaper 46 constitutes a second generator.

Therefore, due to manufacturing errors, the diameter of the photosensitive drum 25 differs from the designed value, the cross-sectional shape of the photosensitive drum 25 is not a perfect circle, or the rotation axis is shifted from the center of the photosensitive drum 25. Even if the peripheral speed of the photoconductor drum 25 is not constant due to the attachment or slipping or rattling in the drive system of the photoconductor drum 25, or the peripheral speed fluctuates locally, the photoconductor drum 25
And the moving speed of the recording medium 13 can be made equal.

Similarly, even when the transport speed of the transport belt 15 is not constant due to a manufacturing error, the peripheral speed of the photosensitive drum 25 and the moving speed of the recording medium 13 can be made equal. Therefore, the surface of the photoconductor drum 25 and the surface of the recording medium 13 do not rub against each other in the transfer section, so that the toner image transferred to the recording medium 13 is not disturbed or misaligned. As a result, the image quality does not deteriorate.

Next, a third embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol. FIG. 9 is a perspective view of a photosensitive drum, a conveyance belt, and a registration roller according to the third embodiment of the present invention.

In the drawing, reference numeral 12 denotes a pair of registration rollers, and one of the registration rollers 12 has a magnetic pattern tape 35 adhered to one end of the outer peripheral surface. The magnetic pattern tape 35 has the same configuration as the magnetic pattern tape 31. Reference numeral 36 denotes a pickup for detecting a change in the magnetic pattern of the magnetic pattern tape 35. The pickup 36 is opposed to the lowermost end of the one end of the registration roller 12 so as to be close to the magnetic pattern tape 35. An alternating voltage as a sensor output corresponding to the peripheral speed of the registration roller 12 for transporting the recording medium 13 is generated by an induced electromotive force of an alternating magnetic field generated by a change in a magnetic pattern. . Therefore, the peripheral speed of the one registration roller 12 can be detected by the pickup 36.

In this case, the pickup 32 uses the rectangular wave W having the number of leading edges proportional to the peripheral speed of the photosensitive drum 25 as an image carrier in the transfer section.
Detects _A, by a pickup 36 detects the rectangular wave W _D with the number of leading edge which is proportional to the peripheral speed of the registration rollers 12, the rectangular wave W _A phase and a rectangular wave W
The phase of _D is matched. Incidentally, the rectangular wave W _A first speed corresponding value corresponding to the peripheral speed of the photosensitive drum 25, the peripheral velocity of the rectangular wave W _D is the resist roller 12,
That is, a second speed corresponding value corresponding to the moving speed of the recording medium 13 is formed.

Therefore, due to manufacturing errors, the diameter of the photosensitive drum 25 differs from the designed value, the cross-sectional shape of the photosensitive drum 25 is not a perfect circle, or the rotation axis is shifted from the center of the photosensitive drum 25. Even if the peripheral speed of the photoconductor drum 25 is not constant due to the attachment or slipping or rattling in the drive system of the photoconductor drum 25, or the peripheral speed fluctuates locally, the photoconductor drum 25
And the moving speed of the recording medium 13 can be made equal.

Similarly, even when the transport speed of the transport belt 15 is not constant due to a manufacturing error, the peripheral speed of the photosensitive drum 25 and the moving speed of the recording medium 13 can be made equal. Therefore, the surface of the photoconductor drum 25 and the surface of the recording medium 13 do not rub against each other in the transfer section, so that the toner image transferred to the recording medium 13 is not disturbed or misaligned. As a result, the image quality does not deteriorate.

Next, a fourth embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol. FIG. 10 is a side view of the photosensitive drum according to the fourth embodiment of the present invention, and FIG. 11 is a control circuit for controlling the sub-scanning of the motor driving unit and the optical writing device according to the fourth embodiment of the present invention. It is a block diagram of.

In the drawing, reference numeral 25 denotes a photosensitive drum as an image carrier, and a magnetic pattern tape 31 (FIG. 1) is adhered to one end of the outer peripheral surface of the photosensitive drum 25. Pickups 32 and 37 detect changes in the magnetic pattern of the magnetic pattern tape.
Reference numeral 2 denotes a coil disposed to face the lowermost end of the end of the photoconductor drum 25, and the pickup 37 opposes the uppermost end of the end of the photoconductor drum 25 to be disposed close to the magnetic pattern tape 31. The AC voltage _VA is generated by the induced electromotive force of the alternating magnetic field generated by the change in the magnetic pattern. Therefore, the peripheral speed of the photosensitive drum 25 in the transfer section can be detected by the pickup 32, and the pickup 37
Thus, the photosensitive drum 25 and the optical writing device 28 (FIG. 2)
, The peripheral speed of the photosensitive drum 25 in the optical writing unit can be detected.

Reference numerals 41 and 47 denote pickups 3 respectively.
Square wave shape the AC voltage V _A of 2, 37 W _A, a waveform shaper for generating a W _E, 48 is to divide the rectangular wave W _E generated by the waveform shaper 47 to 1 / N, Optical writing device 2
A 1 / N frequency dividing circuit as a sub-scanning synchronizing signal generating means for generating eight sub-scanning synchronizing signals. Incidentally, the speed corresponding rectangular wave W _A first speed corresponding value corresponding to the peripheral speed of the photosensitive drum 25 in the transfer section, a rectangular wave W _E is corresponding to the peripheral speed of the photosensitive drum 25 in the optical writing unit Configure values. Further, the waveform shaper 41 constitutes a first generator, and the reference interval generator 42 constitutes a second generator.

Here, N is the magnetic pattern tape 31
And the resolution of the optical writing device 28 in the sub-scanning direction, that is, the reciprocal of the product of the number of writes per unit length. The magnetic pattern of the magnetic pattern tape 31 is formed such that S poles and N poles are alternately arranged at an interval of, for example, 1/1200 [inch].
If it is 0 [dot / inch], N is 4.

In this case, the peripheral speed of the photosensitive drum 25 is
Accordingly, the writing interval of light by the optical writing device 28 becomes constant.
Light on the photosensitive drum 25
The distance between the electrostatic latent images in the sub-scanning direction
You. In the present embodiment, the phase comparator 43
The rectangular wave W generated by the waveform shaper 41_ARank
Square wave W generated by phase and reference interval generator 42 _B
The phase is compared with that of FIG.
Thus, the rectangular wave W generated by the waveform shaper 41
_AAnd the rectangular wave W generated by the waveform shaper 46
_CCan also be compared.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0053]

As described above in detail, according to the present invention, in an image forming apparatus, an image carrier, an optical writing device for writing an electrostatic latent image on the surface of the image carrier, and A developing device that develops the electrostatic latent image to form a toner image; a transfer device that transfers the toner image to a recording medium; and a second device that generates a first speed corresponding value corresponding to a peripheral speed of the image carrier. Generating means, a second generating means for generating a second speed corresponding value corresponding to a moving speed of the recording medium, and the image carrier for equalizing the first and second speed corresponding values. And control means for controlling the driving means.

In this case, the first speed corresponding value corresponding to the peripheral speed of the image carrier is equal to the second speed corresponding value corresponding to the moving speed of the recording medium. Therefore,
Due to manufacturing errors, the diameter of the image carrier is different from the design value, the cross-sectional shape of the image carrier is not a perfect circle, the rotation axis is mounted off the center of the image carrier, Even if the peripheral speed of the image carrier does not become constant due to slippage or rattling in the drive system, or the peripheral speed fluctuates locally, the peripheral speed of the image carrier and the moving speed of the recording medium are reduced. Can be made equal.

As a result, the surface of the image carrier and the surface of the recording medium do not rub against each other in the transfer section, so that the toner image transferred to the recording medium is not disturbed or shifted. Therefore, the image quality does not deteriorate.

[Brief description of the drawings]

FIG. 1 is a perspective view of a photosensitive drum according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is an enlarged view of a main part of the magnetic pattern tape according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a motor driving unit according to the first embodiment of the present invention.

FIG. 5 is a time chart illustrating an operation of a motor driving unit according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a driving unit of each motor of the four image forming engines according to the first embodiment of the present invention.

FIG. 7 is a perspective view of a photosensitive drum and a transport belt according to a second embodiment of the present invention.

FIG. 8 is a block diagram of a motor driving unit according to a second embodiment of the present invention.

FIG. 9 is a perspective view of a photosensitive drum, a conveyance belt, and a registration roller according to a third embodiment of the present invention.

FIG. 10 is a side view of a photosensitive drum according to a fourth embodiment of the present invention.

FIG. 11 is a block diagram of a control circuit that controls sub-scanning of a motor driving unit and an optical writing device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Registration roller 13 Recording medium 15 Conveyor belt 25 Photoreceptor drum 28 Optical writing device 29 Developing device 30 Transfer device 41, 46 Waveform shaper 42 Reference interval generator 44 Motor drive circuit 45 Motor 48 1 / N frequency dividing circuit

Claims (6)

[Claims] 1. An image carrier, (b) an optical writing device for writing an electrostatic latent image on the surface of the image carrier, and (c) a toner image formed by developing the electrostatic latent image. A developing device for forming;
(D) a transfer device for transferring the toner image to a recording medium;
(E) first generating means for generating a first speed corresponding value corresponding to the peripheral speed of the image carrier, and (f) generating a second speed corresponding value corresponding to the moving speed of the recording medium. An image forming apparatus comprising: a second generation unit; and (g) a control unit that controls a driving unit of the image carrier to make the first and second speed corresponding values equal. 2. The apparatus according to claim 1, wherein the first speed corresponding value is generated based on a sensor output corresponding to a peripheral speed of the image carrier, and the second speed corresponding value is a reference waveform. Image forming device. 3. The first speed corresponding value is generated based on a sensor output corresponding to a peripheral speed of the image carrier, and the second speed corresponding value is a conveyance speed of a conveyance belt that conveys a recording medium. The image forming apparatus according to claim 1, wherein the image is generated based on a sensor output corresponding to the speed. 4. The first speed corresponding value is generated based on a sensor output corresponding to a peripheral speed of the image carrier, and the second speed corresponding value is a peripheral speed of a registration roller for conveying a recording medium. The image forming apparatus according to claim 1, wherein the image is generated based on a sensor output corresponding to the speed. 5. The image according to claim 1, further comprising a sub-scanning synchronization signal generating unit for generating a sub-scanning synchronization signal of the optical writing device based on a speed corresponding value corresponding to a peripheral speed of the image carrier. Forming equipment. 6. The image forming apparatus according to claim 1, wherein the image carrier, the optical writing device, the developing device, and the transfer device are arranged in a plurality in a conveying direction of the recording medium.