JPH09277609A - Multicolor image recording apparatus and misregistration adjusting processing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and inexpensively correct color shift by detecting color shift at every apparatus possible to generate by mechanical driving by simple constitution. SOLUTION: A transfer drum sensor 34 forms a TOP signal and a CPU 31 detects the formed TOP signal. After a predetermined time is elapsed from a point of time when the TOP signal is detected, color images based on respective color image signals VDO are developed to be transferred to a transfer drum 6 and processing detecting the leading ends of the respective transferred color images by an image detection sensor 32 is repeated corresponding to the number of colors and the CPU 31 leads out the difference with a predetermined plan value to as the positional shift quantities of the respective leading ends and controls the sending-out timings of the respective color image signals on the basis of the positional shift quantities.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image recording apparatus capable of recording a multicolor image by superimposing and transferring each color image onto a recording medium transferred to a transfer drum, and a positional deviation adjustment of the multicolor image recording apparatus. It relates to a processing method.

[0002]

2. Description of the Related Art FIG. 12 is a schematic sectional view showing an example of this type of color printer, for example, an electrophotographic color laser printer.

In the figure, the photosensitive drum 1 rotates in the direction of the arrow at a predetermined speed and is charged by the charger 2 to a predetermined polarity and voltage value.

Next, the recording paper P is fed one by one from the paper feed cassette 10 by the paper feed roller 9 at a predetermined timing. When the front edge of the paper is detected by the detector 3, the laser light modulated by the image signal is emitted from the semiconductor laser 19 toward the polygon mirror 21, and the laser light is scanned by the polygon mirror 21 and then the lens and It is guided onto the photosensitive drum 1 via the mirror. A developing device unit 5 is rotatable.

Then, the first electrostatic latent image is developed by the developing device 4a, and a magenta first toner image is formed on the photosensitive drum 1.

Immediately before the leading edge of the recording paper P fed at a predetermined timing reaches the transfer start position, a transfer bias voltage having a polarity opposite to that of the toner is charged on the transfer drum 6 by the charger 22.
And the first toner image is transferred onto the recording paper P, and at the same time, the recording paper P is electrostatically attracted to the surface of the transfer drum 6 via the gripper 14. Reference numeral 11 is a pressing roller.

Next, the toner image developed on the photosensitive drum 1 is transferred to the recording paper P by scanning with the laser beam. After the transfer, the developing device unit 5 is switched to the developing device 4b, a second electrostatic latent image is formed on the photosensitive drum 1, and when it is developed by the developing device 4b, a cyan toner image is formed on the recording paper P. It is transcribed according to. Next, when a third electrostatic latent image is formed and developed by the developing device 4c, the yellow toner image is transferred onto the recording paper P in alignment with it.

Then, a fourth electrostatic latent image is formed, developed by the developing device 4d, and a black toner image is transferred onto the recording paper P in alignment with it. When the front end of the transferred recording paper P approaches the position of the separation claw 16, the separation claw 16 contacts the surface of the transfer drum 6 and separates the recording paper P from the transfer drum 6. The separation claw 16 returns to the original position when the rear end of the recording paper P separates from the transfer drum 6. At that time, the charger 15
Thus, the accumulated charge on the recording paper P is removed, the separation of the recording paper P by the separation claw 16 is facilitated, and the air discharge during the separation is reduced.

Thus, the recording paper P separated from the transfer drum 6 enters the fixing device 8 and is heated by the halogen heater from the inside of the fixing roller. By passing through the fixing roller, the toner is thermally melted and fixed as an image, and is discharged to the discharge tray 18.

[0010]

Since the conventional color recording apparatus is constructed as described above, it is essential that the planes of the respective colors are properly overlapped when forming one color image by superposing multicolored images. Is. However, there is a problem in that the image position deviation of each color occurs due to factors such as the behavior of the rotating body drum and a slight deviation in the synchronization between the laser scanning and the rotating body. These factors vary in degree due to variations among individual machines.

Therefore, since each machine needs its own correction, in order to make the image quality constant at the time of factory shipment, the steps of checking the above-mentioned color shift state and adjusting for correcting the color shift are performed one by one in the manufacturing process. It is set up and dealt with.

The present invention has been made to solve the above problems, and an object of the present invention is to detect the position of the leading edge of each color image which is detected by detecting a predetermined member and sequentially developed and transferred to a transfer body. By detecting and controlling the transfer timing of each color image from the detected position and the reference position, the color shift of each device that can be generated by mechanical drive with a simple configuration is detected, and the color shift is accurately performed. An object of the present invention is to provide a multicolor image recording apparatus that can be corrected at low cost and a positional deviation adjustment processing method for the multicolor image recording apparatus.

[0013]

According to a first aspect of the present invention, a multicolor image is recorded by sequentially transferring color images, which are developed for each color on a photoconductor by a plurality of developing materials, to a transfer body. In a multicolor image recording apparatus, a signal generating unit that detects an image writing reference position of the transfer body and generates an image writing signal, and a color image transferred from the photoconductor to the transfer body based on the image writing signal. Of the color image derived by the derivation means, and a derivation means for deriving a displacement amount of the tip position of each color image from each color image position and the reference position detected by the detection means. And a control means for controlling the image writing timing of each color image in synchronization with the image writing signal based on the tip position displacement amount.

In a second aspect of the present invention, the detecting means is capable of detecting the density of an image transferred on the transfer drum.

According to a third aspect of the present invention, the detecting means includes a first light source that illuminates an image when the image density is detected, and a second light source that illuminates an image when the leading edge of the image is detected. It has a switching unit for switching the drive of the first light source and the driving of the second light source, and the exposure spot diameter for irradiating the transfer material is adjusted by the switching unit.

According to a fourth aspect of the present invention, the detecting means adjusts a facing distance between a light source for irradiating the transfer body and the transfer body when the image density is detected and when the leading edge of the image is detected. The exposure spot diameter for irradiating the transfer material is adjusted by the adjustment member.

A fifth aspect of the present invention relates to a multicolor image recording apparatus for recording a multicolor image by sequentially transferring color images, which are developed for each color on a photoconductor by a plurality of developing materials, to a transfer body. In the misregistration adjustment processing method, a signal generating step of detecting an image writing reference position of the transfer body to generate an image writing signal, and a color image transferred from the photoconductor to the transfer body based on the image writing signal. A detection step of detecting the tip position of each color image, a deriving step of deriving the tip position deviation amount of each color image from the detected color image position and the reference position, and a derived step based on the derived tip position deviation amount of each color image. Adjusting step for adjusting the image writing timing of each color image in synchronization with the image writing signal.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 is a block diagram for explaining the arrangement of the main parts of a multicolor image recording apparatus according to the first embodiment of the present invention.

In the figure, reference numeral 1 is a photosensitive drum, on which an electrostatic latent image is formed by a laser scanning unit 33. The electrostatic latent image is developed by a developing unit (not shown) to be visualized as a toner image, and the toner image is transferred to the transfer drum 6 as the photosensitive drum 1 rotates in the arrow direction.
The transferred image is detected by the image detection sensor 32 as the rotation advances.

A vertical synchronizing signal (hereinafter, TOP signal) is generated by the transfer drum sensor 34 according to the rotation of the transfer drum 6. Further, a horizontal synchronizing signal (BD signal) is generated from the laser scanning unit 33 according to the rotation of the polygon motor, and both signals are input to the CPU 31.

In the multicolor image recording apparatus having the above-mentioned structure, the first invention is a multicolor image recording method in which a plurality of developing materials sequentially transfer color images developed on the photoconductor for each color to the transfer body. In the multicolor image recording apparatus for recording the image, a signal generation unit that detects an image writing reference position of the transfer body and generates an image writing signal, and a signal is transferred from the photoconductor to the transfer body based on the image writing signal. Detecting means for detecting the tip position of the color image, deriving means for deriving the tip position displacement amount of each color image from each color image position and the reference position detected by the detecting means, and the deriving means. The transfer drum sensor 34 has a control unit that controls the image writing timing of each color image in synchronization with the image writing signal based on the amount of displacement of the leading edge of each color image. Deployment flag to detect (described later) to generate the TOP signal, after CPU31 from the detection of the TOP signal the generated a predetermined time elapses, the color image signals V
The color image based on DO is developed and transferred to the transfer drum 6, and the front end of each of the transferred color images is detected by the image detection sensor 32.
The CPU 31 derives the difference from the predetermined design value to as each tip position deviation amount, and based on each tip position deviation amount, each color image signal VD is detected.
It is possible to control the sending timings of OM, VDO-C, VDO-Y, and VDO-Bk, and match the image leading edge position for each color as shown in FIG. 4 to correct the color shift unique to each device. And

In a second aspect of the invention, the detecting means (image detecting sensor 32) can detect the image density transferred to the transfer drum, the image detecting sensor 32 functions as an image density sensor, and the image leading edge position. It also has a function as a detection sensor, and can reduce the sensor cost.

In a third aspect of the present invention, the detection means (image detection sensor 32) includes a first light source (LED2 shown in FIG. 6) for illuminating an image when the image density is detected, and an image when the tip of the image is detected. Second light source for irradiating light (LED shown in FIG. 6
1) and a switching unit (LED driver 37) for switching the driving of the first light source and the second light source, and the exposure spot diameter for irradiating the transfer material is adjusted by the switching unit to obtain an image. The detection sensor 32 enables switching between the function as an image density sensor and the function as an image tip position detection sensor.

The image shift detection process of the multicolor image recording apparatus according to the present invention will be described below with reference to FIGS.

FIG. 2 is a timing chart showing an image position deviation detection state by the CPU 31 shown in FIG.

In FIG. 2, tBD is the time (BD count number) from the input of the TOP signal to the writing of the actual image, and a margin of several BD lines is secured in advance for later correction.

“To” is a design value of the time required for the photosensitive drum 1 to rotate, transferred to the transfer drum 6, and reach the position of the image detection sensor 32 after the image formation by the laser scanning unit 33 is started. . Therefore, there is a predetermined time difference between the image signal VDO and the time until the image detection sensor 32 detects the sensor signal SENSOR output by detecting the leading edge of the image, and the transfer drum 6 may vary for each color. This indicates that the positions of the respective images drawn above are displaced in the sub-scanning direction.

The state is shown by the sensor signals SE of the respective colors.
NSORM, SENSORC, SENSORY, SEN
It is SORBk. Note that tM, tC, tY, and tBk are shift amounts of the respective colors. Whether this value is positive or negative, the following processing can be similarly performed.

FIG. 3 is a flow chart showing an example of the image position detection processing procedure of the multicolor image recording apparatus according to the present invention. Note that (1) to (9) indicate each step.

First, when the image detection process is started, the CPU
31 waits for the input of the TOP signal (1), and when the TOP signal is input, the laser scanning unit 33 starts from that point.
When the counting of the number of BD signals output from (2) is started and the counted number is counted by a predetermined value CN (corresponding to the time tBD until the actual image is written in FIG. 2) (3), BD Image signal VD synchronized with the signal
O is sent to the laser drive circuit, and the BD signal counting process is restarted (4).

Next, the latent image drawn by the laser is developed by a developing unit (not shown) and transferred to the transfer drum 6 (5). After that, when the leading edge of the transferred image is detected by the image detection sensor 32 (6), BD counting is stopped (7), and the value counted up to that point is temporarily stored in the internal memory.

Then, the design value to of the time of the printing system is subtracted from the stored count value to calculate a deviation value tX indicating how many cycles of the BD signal the actual printing is different from the design value to. Then (8), the internal memory is temporarily stored. Then, the second color and the subsequent steps are similarly performed. When all the colors are finished (9), the image position checking process is ended. As a result, the shift value tX (the shift value tM, tC, tY, tBk for each color) is stored in the internal memory of the CPU 31.

Next, the shift amounts tM, tC,
A positional deviation avoiding process in actual image printing based on tY and tBk will be described.

FIG. 4 is a timing chart showing the image position deviation correction processing state by the CPU 31 shown in FIG. 1. The same parts as those in FIG. 2 are designated by the same reference numerals.

As shown in this figure, the shift values tM, tC, tY, tBk calculated and stored by the above detection processing are stored.
By adjusting the writing timing of the image signal of each color based on, the design value to of the time required for the writing position of each color on the transfer drum 6 to be transferred to the transfer drum 6 and reach the position of the image detection sensor 32 It is possible to match with each.

The positional deviation adjustment process of the multicolor image recording apparatus according to the present invention will be described below with reference to the flowchart shown in FIG.

FIG. 5 is a flow chart showing an example of the positional deviation adjustment processing procedure of the multicolor image recording apparatus according to the present invention. Note that (1) to (7) indicate each step.

When the image is printed, the CPU 31 sets tBD-tX (X = M, C, Y, Bk) obtained by dividing the time from the TOP signal of each color to the VDO signal by the BD cycle in the counter.

First, when image printing is started, waiting for a TOP signal from the transfer drum sensor 34 to be input,
When the TOP signal is input, counting of the BD signal is started from the input time (2), and the BD signal is set to (tBD-t
When M times have been counted (3), that is, when the counting is finished (4), the image signal VDO (first, the image signal VDO
-M) is sent (5), and thereafter, an image of M color is formed on the transfer drum 6 by the image forming process (6).

Thereafter, similarly to each color, from the TOP signal to tBD-t
When BD is counted X times (X = M, C, Y, Bk), an image signal is sent out, and when image formation is completed for all colors (7), the process is terminated.

Correspondence between the present embodiment and each step of the fifth invention and its action will be described with reference to FIGS.

A fifth aspect of the present invention is a misregistration adjustment process for a multicolor image recording apparatus for recording a multicolor image by sequentially transferring color images, which are developed for each color on a photoconductor by a plurality of developing materials, to a transfer body. In the method, a signal generating step (step (2) in FIG. 3) of detecting an image writing reference position of the transfer body (transfer drum 6) and generating an image writing signal, and the photoconductor based on the image writing signal. From the detection step (step (6) in FIG. 3) of detecting the tip position of the color image transferred from the transfer body to the transfer member, the tip position deviation amount of each color image is calculated from the detected position of each color image and the reference position. Derivation step of deriving (steps (7) and (8) in FIG. 3) and adjustment for adjusting the image writing timing of each color image synchronized with the image writing signal based on the derived tip position displacement amount of each color image. Process Figure 5 Step (1) is running and to (7)), i.e., CPU 31, not shown ROM
By executing the control program stored in the storage medium such as
It is possible to correct the color shift unique to each device by matching the image leading edge position for each color.

As a result, as shown in the chart of the printing positions of the respective colors in FIG. 4, the writing positions of all the colors exactly match on the transfer drum 6.

By the way, the image detection sensor 32 used for image detection can also serve as an image density sensor.

At this time, the image density sensor applies light to a wide range of the patch and measures the reflected light in order to measure the averaged density in a certain range. However, in the present invention, the edge of the image front end must be detected, so the spot diameter of the light source must be reduced.

FIG. 6 shows the image detection sensor 32 shown in FIG.
FIG. 6 is a diagram illustrating a detection operation when the is configured by a density sensor.

As shown in this figure, when the density sensor provided in this type of multicolor image recording apparatus is also used as the image detection sensor 32 shown in FIG. 1, in preparation for the above detection,
Equipped with a mechanism to change the spot diameter.

That is, the light source LED2 (the spot diameter of LED1 is the light source L when used as a normal density sensor)
In addition to the spot diameter of ED2), a light source LED1 as another light emitting source is provided. The LED 2 is a conventional light source for density detection and has a wide spot diameter S2. On the other hand, the light source LED1 can reduce the spot diameter S1 by slightly increasing the distance from the lens LEN. In addition, 37 is an LED driver, which switches the light source LED2 and the light source LED1 by a control signal from the CPU 31 to light them.

FIG. 7 is a characteristic diagram showing the signal level when the light receiving element receives the light source LED1 shown in FIG.
The vertical axis represents the sensor signal level from a light receiving element (not shown), and the horizontal axis represents time.

FIG. 8 is a characteristic diagram showing the signal level when the light receiving element is received by the other light source LED2 shown in FIG. 6, in which the vertical axis represents the sensor signal level from the light receiving element (not shown) and the horizontal axis. Indicates the time.

As shown in these figures, the light source LED
When the spot diameter is small as in No. 1, the sensor signal level becomes steep and the edge can be detected.

On the other hand, when the spot diameter is rather wide as in the light source LED2, it is suitable when light having a wide spot diameter is applied to a wide range of the patch and the averaged density is measured.

[Second Embodiment] In the first embodiment, two light sources are provided, the spot diameter is changed according to the image object to be detected by the image detection sensor 32, and the density sensor is set to the front end of the color image. Although the case where the image sensor is also used as the detection sensor has been described, the facing distance between the image detection sensor 32 and the transfer drum 6 is increased so that the spot diameter is smaller than that of the density sensor even if there is only one light source. May be used also as the image detection sensor 32. Hereinafter, the embodiment will be described.

FIG. 9 is a schematic external view for explaining the structure of a dual-purpose sensor provided in the multicolor image recording apparatus showing the second embodiment of the present invention, and FIG. 10 is a schematic view of the transfer drum shown in FIG. It is a partial cross-sectional view, and the same components as those in FIG. 1 are denoted by the same reference numerals.

In these figures, the image detection sensor 32
The support member is configured to be movable in a fan shape around the shaft 43. A roller 44, a part of which is in contact with a part of the transfer drum 6, is provided on the side of the support member opposite to the shaft 43, and thereby the distance to the transfer drum 6 is kept constant.

Therefore, as the transfer drum 6 rotates, the roller 44 rides on the protruding member 41 provided at the end of the transfer drum 6, and the distance between the image detection sensor 32 itself and the surface of the transfer drum 6 increases.

In a multicolor image recording apparatus constructed in this way, a fourth invention is the detection means (image detection sensor 3
2) is a light source (one LE not shown) for irradiating the transfer member at the time of detecting the image density and at the time of detecting the image front end.
D) has an adjusting member (protrusion member 41, roller 44, shaft 43 of the supporting member) for adjusting the facing distance between the transfer member and the transfer member by the protrusion member 41, the roller 44 and the shaft 43 of the supporting member. By adjusting the diameter of the exposure spot to be irradiated, the image detection sensor 32 can switch between the function as an image density sensor and the function as an image tip position detection sensor.

FIG. 11 is a timing chart for explaining the changing state of the spot diameter of the light source provided in the image detection sensor 32 shown in FIG.

As shown in this figure, after the TOP signal, when the drum outer diameter becomes large in the area where the image leading edge is detected,
That is, when the roller 44 rides on the protruding member 41 provided at the end of the transfer drum 6 as the transfer drum 6 rotates, the facing distance between the image detection sensor 32 itself and the surface of the transfer drum 6 increases, and accordingly. The spot diameter of the sensor light source on the transfer drum 6 becomes smaller.

Thus, the image detection sensor 32 having one light source can be used both as the density sensor and the image leading edge detection sensor.

[0061]

As described above, according to the present invention,
By detecting a predetermined member, the tip position of each color image that is sequentially developed and transferred to the transfer body is detected, and the transfer timing of each color image is controlled from the detected position and the reference position.
The present invention has an effect that a color shift for each device that can be generated by mechanical driving is detected with a simple configuration, and the color shift can be accurately corrected at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a main part configuration of a multicolor image recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing an image position shift detection state by the CPU shown in FIG.

FIG. 3 is a flowchart showing an example of an image position detection processing procedure of the multicolor image recording apparatus according to the present invention.

4 is a timing chart showing an image position deviation correction processing state by the CPU shown in FIG.

FIG. 5 is a flowchart showing an example of a positional deviation adjustment processing procedure of the multicolor image recording apparatus according to the present invention.

FIG. 6 is a diagram illustrating a detection operation when the image detection sensor illustrated in FIG. 1 is configured by a density sensor.

7 is a characteristic diagram showing signal levels when a light receiving element is received by the light source shown in FIG.

8 is a characteristic diagram showing a signal level when a light receiving element is received by another light source LED shown in FIG.

FIG. 9 is a schematic external view illustrating the configuration of a dual-purpose sensor provided in the multicolor image recording apparatus according to the second embodiment of the present invention.

FIG. 10 is a cross-sectional view of a main part of the transfer drum shown in FIG.

FIG. 11 is a timing chart for explaining a variation state of a spot diameter of a light source provided in the image detection sensor shown in FIG.

FIG. 12 is a schematic sectional view showing an example of this type of color printer.

[Explanation of symbols]

 1 Photosensitive Drum 6 Transfer Drum 31 CPU 32 Image Detection Sensor 33 Laser Scanning Unit 34 Transfer Drum Sensor

Claims (5)

[Claims] 1. A multi-color image recording apparatus for recording a multi-color image by sequentially transferring a color image, which is developed for each color on a photoconductor by a plurality of developing materials, to a transfer body, and an image writing standard of the transfer body. A signal generating means for detecting a position to generate an image writing signal; a detecting means for detecting a tip position of a color image transferred from the photoconductor to the transfer body based on the image writing signal; and a detecting means. Derivation means for deriving the tip position deviation amount of each color image from the detected color image position and the reference position, respectively, and synchronization with the image writing signal based on the tip position deviation amount of each color image derived by the deriving means. A multicolor image recording apparatus comprising: a control unit that controls the image writing timing of each color image. 2. The multicolor image recording apparatus according to claim 1, wherein the detection unit is capable of detecting the density of the image transferred to the transfer drum. 3. A first light source that illuminates an image when detecting the image density, a second light source that illuminates an image when detecting the leading edge of the image, the first light source and the first light source. 2. The multicolor image recording apparatus according to claim 1, further comprising a switching unit that switches driving of two light sources, and the exposure unit diameter for irradiating the transfer material is adjusted by the switching unit. 4. The detecting means includes an adjusting member that adjusts a facing distance between a light source that illuminates the transfer body and the transfer body when the image density is detected and when the image leading edge is detected,
2. The multicolor image recording apparatus according to claim 1, wherein the exposure spot diameter for irradiating the transfer material is adjusted by the adjusting member. 5. A misregistration adjustment processing method for a multicolor image recording apparatus for recording a multicolor image by sequentially transferring color images, which are developed for each color on a photoconductor by a plurality of developing materials, to a transfer body. A signal generating step of detecting an image writing reference position of the transfer body to generate an image writing signal, and a detecting step of detecting a leading end position of a color image transferred from the photoconductor to the transfer body based on the image writing signal. And a derivation step of deriving a tip position displacement amount of each color image from the detected color image position and a reference position, and synchronizing with the image writing signal based on the derived tip position displacement amount of each color image. And a step of adjusting an image writing timing of each color image, which is a position shift adjusting method of the multicolor image recording apparatus.