JP3313737B2 - Color image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, there is provided a generating means for generating color separation data for forming a color image, and sequentially superimposing and recording each color image on an image carrier based on the color separation data generated from the generation means. The present invention relates to a color image recording apparatus provided with recording means.

[0002]

2. Description of the Related Art Conventionally, in this type of apparatus, each color image (magenta, magenta,
A full-color image recording apparatus has been put to practical use by sequentially transferring cyan, yellow, and black).

In such a case, in order to transfer each color image without color shift, a sensor is arranged on the outer peripheral portion of the transfer drum, and it is detected that the rotation of the transfer drum has reached a predetermined position. Is used as a color superposition timing signal.

The same detection signal is used to generate a color separation signal.

[0005]

However, in the above-described conventional example, the peripheral speed of the transfer drum changes due to a change in the load of the transfer drum when the recording paper is placed on or peeled off from the transfer drum. Alternatively, a change in the peripheral speed of the photosensitive drum occurs due to a change in the contact of the cleaning blade in contact with the photosensitive drum, and as a result, the peripheral speed of the transfer drum in contact with the outer peripheral portion of the photosensitive drum changes. appear.

Due to these changes, the interval between the above-mentioned detection signals is not constant, and as a result, a timing shift occurs between the generation of the color separation signal and the recording of the color image, and the color deviation occurs in the recorded image. When the toner on the photosensitive drum is simultaneously transferred to the paper while the paper is electrostatically attracted to the transfer drum, the difference between the feed speed of the registration roller for sending the paper to the transfer drum and the peripheral speed of the transfer drum causes The paper slides very slightly on the transfer drum. This is the transfer of four colors
The paper is limited to the first color, and during the transfer of the other three colors, the paper is in close contact with the transfer drum and does not slip. As a result of this,
In a recorded image, there has been a problem that only the first color image is recorded with a shift.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and generates a reference signal indicating that a predetermined portion common to each color of the image carrier has passed a predetermined position. The reference signal generation period is measured, and the measured
For correcting color misregistration based on the generation cycle of the reference signal.
It is an object of the present invention to obtain a color image recording device capable of correcting a color shift due to a rotation speed fluctuation of an image carrier by independently obtaining a correction value and correcting an output timing of each color separation data, and performing good color image recording. And

[0008]

According to the present invention, there is provided a color recording apparatus which generates color separation data for forming a color image, based on the color separation data generated by the generation means. A color image recording apparatus comprising: a recording unit that sequentially records each color image on the image carrier; a driving unit that rotates the image carrier; and a driving unit that rotates the image carrier by the driving unit. Reference signal generating means for generating a reference signal indicating that a predetermined portion common to each color of the image carrier has passed a predetermined position, measuring means for measuring a generation cycle of the reference signal, and the measuring means The color shift is compensated based on the measured generation cycle of the reference signal.
Setting means for independently setting a correction value for correcting each color separation data;
Control means for independently correcting and controlling the output timing of each color separation data for each color based on the correction value .

Further, the color image recording apparatus has scanning means for scanning a document, and the control means controls a scanning start timing for each color. Further, the image carrier is a recording sheet held on a transfer drum. A generating unit that generates color separation data for forming a color image ; and an image forming unit that sequentially forms each color image on a single photoconductor based on the color separation data generated by the generating unit . Each color formed on the photoconductor
In the color image recording apparatus having a transfer means for Ru is transferred to overlap an image on a recording medium, holding for holding the recording medium
A drive unit for rotating the member , and a common color for each color of the holding member.
Signal generating means for generating a reference signal indicating that a predetermined portion of the recording medium has passed a predetermined position, and the leading end of the recording medium held by the holding member reaches the transfer position after the generation of the reference signal Measuring means for measuring the time until each color, setting means for independently setting a color shift amount for each color separation data based on a difference in time for each color measured by the measuring means, and setting Control means for independently correcting and controlling the output timing of each color separation data for each color based on each color shift amount set by the means. Further, the color image recording apparatus has a memory for storing the color separation data, and the control means controls a timing of outputting the color separation data from the memory for each color.

[0010]

FIG. 1 is a sectional view for explaining the arrangement of a color copying apparatus according to a first embodiment of the present invention.
Reference numeral denotes a reader unit, which includes a document table (platen glass) 11, a document illumination lamp 12, an imaging lens 13, and an image sensor (for example, CC)
D, etc.), an optical motor (stepping motor) 15, etc., and an electro-optical scanning unit which scans and moves integrally with a document illumination lamp (illumination lamp) 12 is previously provided. Reading is performed at a constant speed determined according to the set magnification and the like. An operation unit, which will be described later, is provided around the document table (platen glass) 11, and switches for setting various modes relating to a copy sequence, a display for display, and a display are provided. 34 is a first mirror, 35 is a second mirror, and 36 is a third mirror. Reference numeral 2 denotes a document feeder, which includes feed rollers 30 and 31, pick-up rollers 32 and 33, and feeds transfer paper 63 and the like in accordance with a drive command from the controller 16. Reference numeral 3 denotes an image forming unit, which includes a scanner motor 17, a polygon mirror 18, a photosensitive drum 19,
It is composed of a cleaner section 20 (having a cleaner blade), and a controller section 16 processes an output of the image pickup device 14 to produce a laser beam from a laser light source based on an image signal obtained.
The beam is imaged on the photosensitive drum 19 to form an electrostatic latent image. Reference numeral 4 denotes an image transfer unit, which is an adsorption charger 21, a transfer charger 22, a separation charger 23, a high-pressure unit 24, a separation pressing roller 25, a separation claw 26, a transfer drum 27, a suction roller 28, and a registration roller 29. The registration roller 2 is controlled by the sheet feeding roller 30 or the sheet feeding roller 31.
The transfer paper 63 fed to the position 9 is transferred to a registration roller 29.
As a result, the transfer paper 63 is fed again at the timing when the image head position with the photosensitive drum 19 is synchronized. Then, the transfer paper 63 fed by driving the registration roller 29 is electrostatically attracted to the transfer drum 27 by the attraction roller 28 and the attraction charger 21 serving as opposing electrodes. The transfer charger 22 transfers each color developer developed on the photosensitive drum 19 to the transfer paper 63. The separation charger 23 serving as the charge elimination charger includes the transfer paper 6.
The charge of No. 3 is eliminated, and the attraction force with the transfer drum 27 is reduced. At this time, a high voltage is applied to the transfer paper 63 by the high voltage unit 24 in order to prevent the developer from slightly moving due to the isolated discharge. Reference numeral 5 denotes a developing unit, which includes developing units 5a to 5d and the like.
A lifter mechanism (lift-up mechanism), which is configured to be reciprocated in a direction indicated by an arrow by a motor described later, and is not shown
Thus, the developing sleeve can be brought close to / located at a predetermined position of the photosensitive drum 19 so that the developing sleeve can be brought into contact with the photosensitive drum 19. The developing devices 5a to 5d contain, for example, black, yellow, cyan, and magenta developers in this order. Reference numeral 6 denotes a fixing unit, and a fixing roller 6
The toner is fixed on the transfer paper 63 by the a and pressure rollers, and the paper is discharged to the paper discharge tray 6b.

The controller 16 also serves as an adjusting means, and a driving means for reciprocating the developing units 5a to 5d sequentially moves the selected developing units 5a to 5d so as to move the developing units 5a to 5d in a predetermined manner. Approach / evacuate the photosensitive drum 1
9 to visualize the electrostatic latent image formed in each color. Then, the image developed on the photosensitive drum 19 is transferred onto the transfer paper 63 attracted to the transfer drum 27 by winding means (consisting of the attracting charger 21 and the attracting roller 28).
At this time, the controller 16 sets the timing of feeding the transfer paper 63 to be sequentially attracted to the transfer drum 27 to the selected transfer paper size and the photosensitive drum 19 of each of the developing devices 5a to 5d.
Is adjusted based on the arrangement state with respect to the transfer drum 63, and a plurality of transfer papers 63 are attracted to the transfer drum 27 at predetermined intervals, and the timing for feeding and attracting the subsequent transfer paper 63 to the transfer drum 27 is determined.

FIG. 2 shows the controller 16 shown in FIG.
FIG. 42 is a block diagram illustrating the configuration of a CPU.
In accordance with the control program stored in the ROM 43, the copying sequence is generally controlled. Reference numeral 55 denotes a crystal for generating a basic clock of the CPU 42. 44 is RA
M functions as a work memory of the CPU 42 and stores various flag information input from the operation unit 51. Reference numeral 45 denotes an I / O port for outputting a synchronization control signal necessary for image reading. Reference numeral 56 denotes a timer counter, receives from the CPU 42 a reference clock CLK obtained by dividing the basic clock generated by the crystal 55 by 1/4, and outputs a count value 57 of the clock to the CPU 42. 46 is a position sensor (ITOP sensor), and the transfer drum 27
Are detected at predetermined positions (image head positions A and B), and an image front end signal ITOP for determining transfer timing is transmitted to the CPU 42.
Output to

Reference numeral 47 denotes a motor controller for a developing unit.
The developer 48 is driven to move the developing device table (not shown) on which the developing devices 5a to 5d shown in FIG. It is to be noted that, for example, in the case of forming an image of four colors, a plurality of transfer sheets 63 (in this embodiment, a maximum of
In the case where the transfer drum 63 is adsorbed on the transfer drum 27, the transfer timing of the next transfer paper 63 is set as described later.
CPU 42 so as to perform the sheet feeding process with a delay of half a rotation of 7
Determines the sheet feeding and suction timing. Reference numeral 49 denotes an image processing circuit which performs various color separation image processes on the read image data read by the image pickup device 14 to generate a video signal for modulating a laser light source. An optical motor controller 50 reciprocates the original scanning unit.
To control the drive of.

In the color image recording apparatus constructed as described above, when the image recording process is started, the setting means (CPU 42 in the present embodiment) is output as the transport means (transfer drum 27) is driven. The reference signal (output from the position sensor 46 in this embodiment) is monitored to individually set the relative color shift amounts of the respective color separation information, and the control means is controlled based on the relative color shift amounts set by the setting means. The output timing of each color separation information generated by the generating means (output from the image sensor 14) is corrected and controlled by the CPU 42 in this embodiment, and the image based on each color separation information is transferred to the recording medium without color shift. .

FIG. 3 is a plan view of a main part showing an example of the configuration of the operation unit 51 shown in FIG. 2. Reference numeral 801 denotes a keypad for inputting the number of copies, etc., and 802 denotes a display unit for the number of copies.

Reference numeral 805 denotes a switching key for switching between the upper and lower stages of the paper cassette, 806 denotes a display unit for indicating the selected stage of the paper cassette, 807 denotes a copy magnification display unit, 808 denotes a copy magnification decrease key, and 809 denotes a copy magnification increase key. -, 810 is copy-
Operation start key. Reference numeral 811 denotes a color shift measurement key.

FIGS. 4 and 5 show the transfer drum 2 shown in FIG.
7 is a cross-sectional view illustrating a structure of a photosensitive drum and a photosensitive drum; FIG.
The diameter between the transfer drum 27 and the photosensitive drum 19 satisfies the relationship of 2: 1 and the two drums rotate at substantially the same peripheral speed.

As shown in FIG.
The distance on the circumference of the photosensitive drum 19 from the irradiation position S to the joining position tr between the photosensitive drum 19 and the transfer drum 27 is l. Further, the distance from the contact position of the suction roller 28 of the transfer drum 27 to the joining position tr is also equal to the distance l. Therefore, when the leading end of the transfer paper 63 reaches the suction roller 28, the image laser-recorded on the photosensitive drum 19 is transferred to the leading end of the transfer paper 63. When the leading end of the transfer paper 63 electrostatically attracted to a predetermined position of the transfer drum 27 reaches the attraction roller 28, the image laser-recorded on the photosensitive drum 19 is transferred to the leading end of the transfer paper 63. You. The position sensor 46 is shown in FIG. 5 so that the image leading end signal ITOP is output at the timing when the leading end of the transfer paper 63 electrostatically attracted to the predetermined position of the transfer drum 27 reaches the position of the attracting roller 28. As shown, it is installed around the transfer drum 27. The position sensor 46 is fixed to the transfer drum 27, and two light shielding plates 461 and 462 that rotate around the circumference of the transfer drum 27 with the rotation of the transfer drum 27, and are fixed to the copying machine main body. A photo sensor (photo interrupter) 463 for detecting the passage of the light beam through 462 is provided. When the leading end of the transfer paper 63 attracted to the predetermined position of the transfer drum 27 reaches the position of the suction roller 28, the light-shielding plate 461 corresponding to the transfer paper 63 reaches the position of the photo sensor 463, and the image is displayed. Outputs the tip signal ITOP.

The light shielding plate 462 is fixed at a position shifted by 180 degrees on the transfer drum 27 with respect to the light shielding plate 461.

When the transfer paper 63 is attracted to the transfer drum 27, the CPU 42 controls the light-shielding plate 461 so that the leading end of the transfer paper 63 reaches the position of the suction roller 28 at the timing when the light-shielding plate 461 passes through the photosensor 463. A predetermined time is counted from the image leading edge signal ITOP, and the registration roller 29 is controlled.
As described above, when the image leading edge signal ITOP is generated, the image recorded on the photosensitive drum 19 by the laser is transferred to the transfer paper 63.
Recorded at the tip of That is, the image leading end signal ITOP
Functions as a timing signal for starting image recording in the paper feeding direction.

Next, an image processing operation in the copying apparatus of FIG. 1 will be described.

The transfer paper 63 fed by the pick-up roller 32 or the pick-up roller 33 receives the transfer paper 63.
The registration roller 2 is controlled by the roller 30 or the sheet feeding roller 31.
9, the skew is removed, and a predetermined amount of loop is formed. Next, the registration roller 29 rotates,
Suction charger 21 and suction roller 28 also serving as the opposite electrode.
As a result, the transfer paper 63 is attracted to the transfer drum 27. At about the same time, the optical system (document scanning unit) starts scanning, and the image read by the image sensor 14 is taken into the image processing circuit 49.

Then, the image is separated into various colors by an image processing circuit 49 (for example, a known gamma correction).
The original is read by the image sensor 14 and converted into laser light in substantially real time, is deflected and scanned by the polygon mirror 18, and is uniformly charged by the charger.
9 is exposed to form a latent image.

For this latent image, a developing device 5d for magenta toner, a developing device 5c for cyan toner, and a black toner
The developing unit table on which the developing unit 5a is mounted moves horizontally at a predetermined timing to perform a developing process.

The toner image formed on the photosensitive drum 19 is transferred to a transfer paper 63 attracted by the transfer charger 22 or the like. After repeating this series of operations several times for the required developing colors,
The high-pressure unit 24, whose adsorption force is weakened by the separation charger 23 to prevent image disturbance due to separation discharge due to separation, is subjected to curvature separation by the separation pressing roller 25 and the outer separation pressing roller (not shown) while applying high pressure. The sheet is separated by the separation claw 26, fixed by the fixing roller 6a, and then discharged to the discharge tray 6b.

FIG. 6 is a timing chart for explaining the paper feed developing operation in the color image recording apparatus according to the present invention.

In these figures, MD is a motor drive signal output from the I / O port 45, and this signal rotates a transfer drum drive motor (not shown). CPU4
2 drives the transfer drum 27 by the motor drive signal MD, detects the first input image leading edge signal ITOP, feeds the recording paper, and executes a series of copy operations.

PF is a paper feed signal output from the I / O port 45. The register roller 29 is rotated by the paper feed signal PF, and the transfer paper 63 is transferred to the transfer drum 27. Send out. The paper feed signal PF is
After a lapse of a predetermined time from the transmission of the image leading end signal ITOP, the rising edge rises after the transfer paper 63 is completely fed.

VIDEO is an image signal, which is a magenta image signal VIDEOM, a cyan image signal VIDEOC, a yellow image signal VIDEOY, and a black image signal VIDEO.
Each signal is output for a time corresponding to the transfer paper size from the rising edge of the image leading edge signal ITOP, which is the visible timing of image recording. DV is a development signal indicating that development is in progress, and is composed of magenta, cyan, yellow, and black development signals, like the image signal VIDEO.
The development signal VD is a signal that is turned on while the image signal VIDEO modulates the laser light and develops a latent image formed by exposing the uniformly charged photosensitive drum 19.

Hereinafter, the operation of driving the original scanning unit and the optical system will be described in detail with reference to FIGS. 7 and 8.

The original placed on the original table 11 is illuminated by an illumination lamp 12. The optical signal from the document is turned back by the first mirror 34, the second mirror 35, and the third mirror 36, and is projected on the image pickup device 14 through the lens 13.

The illumination lamp 12 and the first mirror 34 are fixed, and the second mirror 35 and the third mirror 36 are also fixed. The first mirror 34, the second mirror 35, and the third mirror 36 scan the original at a speed ratio of 2: 1. The scanning speed of the first mirror 34 is driven by the stepping motor 15 so that the peripheral speed of the photosensitive drum 19 and the peripheral speed of the transfer drum 27 are the same.

The optical motor controller 50 controls the driving of the stepping motor 15. Optical mode
The ta controller 50 receives scanning speed (pulse / second) data 53 and scanning distance (pulse) data 54 from the CPU 42, and inputs a scanning start signal (SS) 52 to control the stepping motor 15. Drive control.

When the original reading scanning is completed, the stepping motor 15 is moved by the number of pulses advanced at a constant scanning speed.
Is rotated in the reverse direction, and the first mirror 34 is returned to the scanning start position. In this embodiment, when the stepping motor 15 is advanced by one pulse, the first mirror 34 scans the original by 0.05 mm. Immediately after each mirror in the stopped state is driven, vibration occurs in the wire connecting the stepping motor 15 and each mirror, and each mirror does not move smoothly. The image signal expands and contracts in the sub-scanning direction. In order to wait for the vibration to subside, the optical system performs a predetermined length of run before reading the original. In this embodiment, the running is performed for 30 mm (60 pulses) regardless of the scanning speed. At typical scanning magnification and scanning length.

FIG. 7 is a correlation diagram showing the relative relationship between the scanning magnification and the scanning speed.

In this embodiment, the peripheral speed of the photosensitive drum 19 and the transfer drum 27 is 100 mm / sec.
Assuming that the scanning speed of Step 4 is 100 mm / sec, the original image is recorded on the transfer paper in the same size. 1st Mira-34
Is doubled (200 mm / sec), the recording image has a size of 50% in the scanning direction, and if the scanning speed of the first mirror 34 is 1/2 (50 mm / sec), the recording image is The size becomes 200% in the scanning direction.

FIG. 8 is a timing chart for explaining the driving operation of the optical system in the color image recording apparatus shown in FIG.
In the loading mode.

The optical system starts from a position having a running distance of 30 mm with respect to the leading end of the document as described above. Therefore, the CPU 42 outputs the image leading edge signal I representing the leading edge of the image.
Time ps required to scan the approach distance to TOP
The scanning start timing signal SS of the optical system is output as soon as possible. That is, as shown in the figure, the CPU 42 counts the time T from the image leading edge signal ITOPb immediately before the image leading edge signal ITOPa representing the leading edge of the image,
The scan start timing signal SS is output. Where T +
PS becomes the image leading edge signal ITOP cycle.

In FIG. 8, for the sake of explanation, the distinction between a and b is shown in the image leading edge signal ITOP. Here, the image leading edge signal ITOPa is a reference signal for image recording, and indicates that the recording paper is at a predetermined position. Image tip signal I
TOPb is a reference signal for image generation (image reading). In the figure, the image leading edge signals ITOPan, bn (n =
1 to N) are paired with each other.

Image top signal ITOPa and image top signal I
It is desirable that the interval I of TOPb is always constant,
It is not always constant.

That is, the speed fluctuation of the transfer drum 27 when the copy paper is electrostatically attracted to the transfer drum 27, and the cleaning blade for the photosensitive drum 19 driven by the same motor as the transfer drum 27. The cycle (I time) of the image leading edge signal ITOP changes due to the motor load change due to the change in the friction coefficient. In this case, the mutual shift of the I time for each developing color is a shift of the image generation timing for each color with respect to the recording paper, and when the colors are overlapped, the color shift occurs.

In order to correct the fluctuation of the time I, that is, the data corresponding to the color shift amount on the recording paper, it is essential to measure some color shift data. Therefore, the time fluctuation of the I time is measured as follows.

FIG. 9 is a flowchart showing an example of a procedure for measuring the time fluctuation of I time in the color image recording apparatus according to the present invention. Note that (1) to (11) indicate each step.

When the color shift measurement key 811 serving as an I-time measurement start key is depressed from the operation unit 51, the measurement mode is entered, and the motor drive signal MD is transmitted from the I / O port 45 to " 1 "
To rotate the photosensitive drum 19 and the transfer drum 27
(1). This waits for the image tip signal ITOP to be generated based on the output from the photo sensor 463.
(2) When the image leading edge signal ITOP is output, the measured value of the I time is set to "0" in the table pointer TP of the RAM 44 (3).

Next, the current count value TC of the timer counter 56 is read (4), and the next image leading edge signal ITOP is read.
Wait for input (5). When the next image leading edge signal ITOP is input, the counter value TC of the timer counter 56 at that time is read (6), and a difference value DC between the previous counter value TC and the present counter value TC is obtained (7).

Next, the difference value DC is written in the I time measurement table of the RAM 44 (8). At that time, I time measurement
The write address of the table is the start address of the I time measurement table.
The value obtained by adding the table pointer value TP to the address is used.

Thereafter, "1" is added to the counter value TC.
(9) It is determined whether or not the counter value TC has become "9" (10). If NO, the process returns to step (5) and YES (IT
If the OP cycle is measured 9 times), the motor drive signal MD is set to "0" to stop the photosensitive drum 19 and the transfer drum 27 (11).

FIG. 10 shows an example of the I time measurement table created on the RAM 44 in this manner.

FIG. 10 is a diagram showing an example of an I time measurement table in the color image recording apparatus according to the present invention.

In this figure, ID0 to ID8 correspond to the eighth
The time data of the periods I0 to I8 of the image leading edge signal ITOP shown in FIG.
Clock number is set.

The time data ID0 to ID8 are as follows.
Since the variation value of the image leading end signal ITOP in a state where the recording paper is not attracted to the transfer drum 27 is
The fluctuation in the speed of the transfer drum 27 when the recording paper is adsorbed or separated from the recording paper is not measured.

However, the cleaning blade, which is the most significant factor for changing the period of the image leading edge signal ITOP, and the variation of the image leading edge signal ITOP caused by the variation of the motor load due to the change of the friction coefficient of the photosensitive drum 19. Has been measured. The value of the cycle I8 is used after the cycle I9. In this embodiment, the cycle data of the image leading end signal ITOP is measured as it is as the color shift amount. However, the data may be tabulated as data of a difference from a fixed ITOP cycle determined by the apparatus configuration. good.

Here, the cycle representing the color shift is the cycle I1
, I3, I5, and I7, which are the magenta differences IM (I1 -I
S), the difference IC for cyan (I3-IS), the difference IY for yellow (I5-IS), and the difference IBK for black (I7
-IS) is the amount of color shift at the time of recording each developed color. In addition,
The theoretical value IS is a value obtained by dividing the calculated peripheral speed of the transfer drum 27.

In this way, the difference IM for magenta
(I1 -IS), the difference IC for cyan (I3 -IS),
When the difference IY (I5 -IS) for yellow and the difference IBK (I7 -IS) for black are obtained, the CPU 42 sends a scanning start timing signal S to the optical motor controller 50.
The correction is performed by controlling the timing of outputting S for each color. That is, by changing the scanning start timing of the reading optical scanning type, the timing of outputting an image is changed and the color shift is corrected.

More specifically, the difference IM for magenta
(I1 -IS), the difference IC for cyan (I3 -IS),
If the value of the difference IY (I5 -IS) for yellow and the value of the difference IBK (I7 -IS) for black are plus, the periods I1, I3, I5 and I7 of the image leading edge signal ITOP are the theoretical values IS.
Indicates longer. That is, the CPU 42 counts the time T corresponding to each of the periods I1, I3, I5, and I7 of the image leading edge signal ITOP longer by that amount, and as a result, the image leading edge signals ITOPa1 to ITO7 serving as reference signals for image recording.
With respect to Pa4, the run-up time PS of the optical system has a constant value by offsetting the variation, and the occurrence of color misregistration is effectively prevented.

As described above, the CPU 42 determines the time T as the color misregistration correction times TM, TC, TY, and TBK corresponding to the recording colors of magenta, cyan, yellow, and black, and corrects the color misregistration from the image leading edge signal ITOPb1. The CPU 42 outputs a scan start timing signal SS to the optical motor controller 50 at the timing counted by the time TM.
Similarly, the color misregistration correction time T is calculated from the image leading edge signal ITOPb2.
At the timing of counting C minutes, the CPU 42
A scanning start timing signal SS is output to the tach controller 50, and the CPU 42 similarly counts the color misregistration correction time TY from the image leading edge signal ITOPb3.
Outputs a scan start timing signal SS to the optical motor controller 50, and similarly, at the timing counted from the image leading edge signal ITOPb4 for the color shift correction time TBK, C
The PU 42 outputs a scanning start timing signal SS to the optical motor controller 50, and the running time P for each color recording is output.
S becomes constant. Hereinafter, similarly for the second and subsequent sheets,
A correction process is performed on the image leading edge signals ITOPb5, b6, b7,..., And the color shift correction times TM, TC, TY,
The running time PS for each color recording is determined as TBK, and the running time PS is fixed.

FIG. 11 is a flow chart showing an example of a color misregistration correction processing procedure in the color image recording apparatus according to the present invention.
It is. Note that (1) to (15) indicate each step.

First, a paper feed signal PF is output (1).
Then, the transfer paper 63 is sent out to the transfer drum 27. When the image leading edge signal ITOP is input (2), counting of the color misregistration correction time TM for magenta recording is started.
(3) When the counting of the color misregistration correction time TM is completed, the scanning start timing signal SS of the optical scanning system is output (4). Next, it waits for the image leading edge signal ITOP to be input twice (5), and when the image leading edge signal ITOP is input twice, starts counting the color misregistration correction time TC for cyan recording (6). When the counting of the color shift correction time TC is completed, the scanning start timing signal S of the optical scanning system is set.
S is output (7). Next, the image leading edge signal ITOP is 2
(8), the counting of the color shift correction time TY for yellow recording is started (9), and when the image leading edge signal ITOP is input twice, the count of the color shift correction time TY is counted. At the end of the process, a scanning start timing signal SS of the optical scanning system is output (10). Next, it waits for the image leading edge signal ITOP to be input twice (11), and when the image leading edge signal ITOP is input twice, starts counting the color shift correction time TY for black recording (12). If the image tip signal ITOP is input twice, the color shift correction time TBK
At the point in time when the counting is completed, the scanning start timing signal SS of the optical scanning system is output (13). Next, it is determined whether a predetermined number of color image recording processes have been completed (14),
If YES, the process is terminated; if NO, the table pointer TP is counted up (15), and the process returns to step (1).
During the color image recording processing, the output timing of the scanning start timing signal SS of the optical scanning system is corrected so that there is no color shift.
Perform image recording processing.

In the above embodiment, the color misregistration amount of each color is automatically measured, and the color misregistration correction times TM, TC, TY, and TBK are counted to keep the run-up time PS of the optical system at the time of recording each color constant. However, a configuration in which the color shift amount is directly input from the operation unit 51 as shown in FIG. 12 may be used. Hereinafter, the operation in that case will be described. [Second Embodiment] FIG. 12 is a plan view of a main part showing another example of the configuration of the operation unit 51 shown in FIG.

In the figure, reference numeral 1201 denotes a keypad for inputting the number of copies and color shift length data, and 1202 a display unit for displaying the number of copies and color shift length data. 1203
Is a clear key, 1204 is a minus key for designating a negative value of the color misregistration length data, 1205 is a switching key for switching between upper and lower rows of paper cassettes, 1206 is a display section showing a paper cassette selection level, Reference numeral 1207 denotes a copy magnification display portion, 1208 denotes a copy magnification decrease key, 1209 denotes a copy magnification increase key, 1210 denotes a copy operation start key, and 12 denotes a copy operation start key.
11 is a color shift amount input key for magenta, 1212 is a color shift amount input key for cyan, 1213 is a color shift amount input key for yellow, and 1214 is a case where color shift input data is a negative value. This is a minus indicator that lights up.

When the operator or serviceman inputs the color shift amount, the color shift amount input keys 1211 and 121 of each color are used.
The user presses one of the buttons 2 and 1213 to specify a correction target color. Thereafter, the user operates the numeric keypad -1201 to input the color shift amount. The input value at this time is in units of 1/100 mm. If the color is shifted rearward in the paper feed direction with respect to the black image, a minus key -1204 is pressed. Based on the color shift data for each color input as described above, the CPU 42 obtains time data IIM, IIC, IIY, and IIBK of the color shift amount for each color, as described later.

That is, in this case, an operator or a serviceman measures the color shift amount in an actual recorded image and inputs the color shift amount as length data. For example, with respect to a black recorded image, a color shifted backward in the paper feeding direction is negative color shift data, and a color shifted forward is positive color shift data as magenta, cyan, and cyan. Input data Z for the length (mm) of each yellow color shift
M, ZC and ZY are operated by an operator or a serviceman.
1 is input from the numeric keypad 1201 or the like. In this case CPU
Reference numeral 42 denotes a value obtained by dividing the input data ZM, ZC, and ZY by the peripheral speed value VT (mm / sec) on the calculated value of the transfer drum 27, and calculating the color shift amount for each color in the same manner as in the first embodiment. Time data I
IM (ZM / VT), IIC (ZC / VT), IIY
(ZY / VT) and IIBK (ZB / VT). However, since black is used as a reference, the time data IIBK is "0".

Therefore, for example, the color shift in the image of the recording field
3, the magenta image V
M is d in the paper feed direction compared to the black image VBK.
, The input data ZM becomes + d, and
Since the cyan image VC is delayed from the black image VBK by d in the paper feed direction, the input data ZC is −
d. Also, the yellow image VY is a black image VB
Since it overlaps with K, the input data ZY becomes "0".

In this manner, the time data IIM (ZM / VT), IIC (ZC / VT),
Once IIY (ZY / VT) and IIBK (ZB / VT) are obtained, the color misregistration correction time TM (T + I
IM), TC (T + IIC), TY (T + IIY), T
Find BK (T + IIBK). Then, these color misregistration correction times TM (T + IIM), TC (T + IIC), and TY
The color shift is corrected by controlling the scanning start timing of the optical scanning system based on (T + IIY) and TBK (T + IIBK). In this embodiment, the running time for each color is not the same as the calculated running time PS, and is corrected to the running time of the color (black) as a reference. As described above, when the color shift amount is manually input, the image leading edge signal ITO
The color shift due to the P cycle shift is also corrected at the same time. [Third Embodiment] FIG. 14 is a diagram showing a main part of a color image recording apparatus according to a third embodiment of the present invention, in which the same components as those in FIG.

In the figure, reference numerals 1404 to 1407 denote page memories serving as image signal sources in this embodiment, which store magenta, cyan, yellow, and black color signals corresponding to respective recording colors. Are sequentially read out from the page memories 1404 to 1407 to form respective color images, and sequentially transferred onto the transfer paper 63, thereby outputting a color image. In addition, the above-described factors of the color misregistration are the same, so that the detailed description is omitted.

Reference numeral 1401 denotes a reflection-type photosensor which detects the passage of a sheet at a point a minute distance m from the contact position tr of the photosensitive drum 19 on the transfer drum 27. A laser scanner 1402 includes a laser, a polygon mirror 18, and a scanner motor 17. . 14
A selector 03 selects one color from the magenta, cyan, yellow, and black color signals in accordance with a 2-bit select signal SEL from the CPU 42. 1408
Reference numerals 1411 to 1411 denote timers for delaying an image reading start signal corresponding to each of the page memories 1404 to 1407. 1
Reference numeral 412 denotes an AND gate for selecting an image leading edge signal ITOP used as an image reading start signal by a gate signal ITOPGT from the CPU 42.

FIG. 15 is a block diagram for explaining the control arrangement of the color image recording apparatus shown in FIG.
The same components as in FIG. 4 are denoted by the same reference numerals.

FIG. 16 shows the transfer drum 27 shown in FIG.
FIG. 4 is a cross-sectional view illustrating an arrangement relationship between the photosensitive drum and a photosensitive drum.

As shown in this figure, the transfer drum 27
The distance from the upper suction roller 28 to the contact position tr, and the distance from the laser irradiation position s on the photosensitive drum 19 to the position tr
The distance to both is 1. When the end of the sheet adsorbed on the transfer drum 27 reaches the position of the adsorption roller 28, the light-shielding plate 461 enters the photo-interrupter 463,
An image tip signal ITOP is output. That is, each of the page memories 1404 to 1414 is simultaneously generated with the image leading edge signal ITOP.
The image based on each color signal read from the image 07 is recorded on the leading edge of the sheet. The color misregistration in this embodiment occurs because the time required for the leading edge of the sheet to reach the transfer point (position tr) after passing the point of the suction roller 28 is not constant. For this reason, the photosensor 1401 is arranged at a point separated by a minute distance m from the transfer point, and the variation in the time required for the leading edge of the paper to reach the transfer point (position tr) from the image leading edge signal ITOP for each recording color is measured. Then, in order to correct the time variation between the colors, each of the page memories 14 after the image leading edge signal ITOP is inputted.
The timing for reading an image from 04 to 1407 is adjusted by timers 1408 to 1411. [Color misregistration amount measuring operation]
The operation of the embodiment will be described.

FIG. 17 is a timing chart for explaining the operation of the color image recording apparatus shown in FIG. Note that the measurement of the color misregistration amount in the present embodiment is executed during the actual copy operation.

First, the CPU 42 outputs a paper feed signal PF, rotates the registration roller 29, and sends out a sheet to the transfer drum 27. After that, of the input image leading edge signals ITOP, the even numbered image leading edge signals ITOP and the M time until the rising edge of the signal MT indicating that the recording paper passes near the position tr are measured for each recording color. . The M time for magenta recording is MM, the M time for cyan recording is MC, the M time for yellow recording is MY, and the M time for black recording is MBBK. When the reading of the image for each color from each of the page memories 1404 to 1407 is uniformly synchronized with the image leading edge signal ITOP, the time required for the image to be latent image formed on the photosensitive drum 19 and developed to reach the position tr is obtained. Should be substantially constant irrespective of the color. However, as described above, the time required for the paper edge to reach the transfer point (position tr) from the image leading edge signal ITOP or the time required for the paper edge to reach the paper leading edge from the image leading edge signal ITOP to the photosensor 1401 arrangement for each color. Due to the difference, color shift occurs on the recording paper. Therefore, a color shift correction process is performed as described below. [Color Misregistration Correction Processing] As described above, M times MM, MC, MY and MBK, which are time data of color misregistration, are measured during the copy operation. In order to correct the color misregistration, the time required for the paper edge to reach the transfer point from the image leading edge signal ITOP is extra for other colors. What is necessary is to delay the image output by that time. .

Therefore, a color having the minimum color shift time data for each color measured during the previous copy is obtained. For example, when the M time MBK during black recording is the minimum, the time at which the paper edge reaches the transfer point (position tr) by MM-MBK with respect to black is delayed during magenta printing. Also, during cyan recording, M time is MC for black.
The end of the sheet arrives at the transfer point (position tr) by -MBK. Further, at the time of yellow recording, the M end of the paper is transferred to the transfer point (position tr
) Slow to reach. On the other hand, since the time for the image to reach the transfer point via the laser scanner 1402 and the photosensitive drum 19 is the same for all four colors, the difference of the M time (M
Color shift occurs only in (M−MBK), (MC−MBK), and (MY−MBK). Therefore, to correct this color shift,
Timers 1408 to 14 adjust the image output timing output from each page memory 1404 to 1407 for the color shift time.
The delay by 11 cancels the color shift.
In the above embodiment, “0” is set in the timer 1407 because black is used as a reference, and the other timers 140
8 to 1410, the difference time (M M −
Time data corresponding to (MBK), (MC-MBK) and (MY-MBK) is set in the CPU 42. Then, at the timing for canceling the color misregistration, that is, the timers 1408 to 14
11 is timed out, each page memory 140
4 to 1407 are the memory read start signals MSM and M
SC, MSY, and MSBK are output.

More specifically, as shown in FIG.
2 inverts the image front end signal ITOP every time the image front end signal ITOP is input. As a result, a start signal GITOP for the memory is generated in synchronization with the passage of the sheet. . When the even-numbered image leading edge signal ITOP is input, the select signal SEL is changed to “0” (magenta), “1” (cyan), “2” (yellow),
By increasing the number to “3” (black), the recording color signal is selected by the selector 1403 in accordance with the passage of the sheet. Also, memory read start signals MSM, MSC, MSY, and MSG provided to page memories 1404 to 1407 are provided.
Since the MSBK is input with a delay to the start signal GITOP from each of the timers 1408 to 1410, the image output VIDE from each of the page memories 1404 to 1407 is provided.
OM, VIDEOC, VIDEOY, VIDEOBK
Is the difference time (MM−M−) with respect to the start signal GITOP.
MBK), (MC-MBK), and (MY-MBK).

As a result, the time from the start of output of each color signal until the end of the sheet reaches the transfer point is all adjusted to M time MBK, and the color shift on the recording sheet is eliminated. In the description of the above embodiment, the color misregistration correction processing in the case where the color misregistration in the black station is used as a reference has been described.

[0075]

As described above, according to the present invention,
A reference signal generation means generates a reference signal indicating that a predetermined portion common to each color of the image carrier has passed a predetermined position, measurement means measures a generation cycle of the reference signal, and Generation of the reference signal measured by the measuring means;
A correction value for correcting color misregistration based on the raw cycle is set independently for each color separation data, and the control means sets the correction value of each color separation data based on each correction value set by the setting means. Since the output timing is independently corrected and controlled for each color, it is possible to correct a color shift due to a change in the rotation speed of the image carrier and obtain a good color image.
In addition, a reference signal indicating that a predetermined portion common to each color of the rotating holding member has passed a predetermined position while holding a recording medium for superimposing and transferring each color image sequentially formed on a single photoconductor. Is generated by the reference signal generating means, and the measuring means measures the time from when the reference signal is generated to when the leading end of the recording medium held by the holding member reaches the transfer position for each color. The color shift amount is independently set for each color separation data based on the time difference for each color measured by the measuring unit, and the control unit sets the color shift amount based on each color shift amount set by the setting unit. Since the output timing of each color separation data is independently corrected and controlled for each color, it is possible to correct a color shift due to a fluctuation in the rotation speed of the image carrier and obtain a good color image.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a configuration of a color copying apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a controller shown in FIG.

FIG. 3 is a plan view of a main part showing a configuration example of an operation unit shown in FIG. 2;

FIG. 4 is a cross-sectional view illustrating a structure of a transfer drum and a photosensitive drum illustrated in FIG.

FIG. 5 is a cross-sectional view illustrating a structure of a transfer drum and a photosensitive drum illustrated in FIG.

FIG. 6 is a timing chart for explaining a sheet feed developing operation in the color image recording apparatus according to the present invention.

FIG. 7 is a correlation diagram showing a relative relationship between a scanning magnification and a scanning speed.

FIG. 8 is a timing chart illustrating a driving operation of an optical system in the color image recording apparatus shown in FIG.

FIG. 9 is a flowchart showing an example of a procedure for measuring a time variation of I time in the color image recording apparatus according to the present invention.

FIG. 10 is a diagram illustrating a color image recording apparatus according to the present invention;
It is a figure which shows the example of a time measurement table.

FIG. 11 is a flowchart illustrating an example of a color misregistration correction processing procedure in the color image recording apparatus according to the present invention.

FIG. 12 is a main part plan view showing another example of the configuration of the operation unit shown in FIG. 2;

FIG. 13 is a schematic diagram showing a color misregistration state in the color image recording apparatus according to the present invention.

FIG. 14 is a diagram illustrating a main configuration of a color image recording apparatus according to a third embodiment of the present invention.

15 is a block diagram illustrating a control configuration of the color image recording apparatus shown in FIG.

16 is a cross-sectional view showing an arrangement relationship between the transfer drum and the photosensitive drum shown in FIG.

FIG. 17 is a timing chart for explaining the operation of the color image recording apparatus shown in FIG.

[Explanation of symbols]

 14 Image Sensor 19 Photosensitive Drum 27 Transfer Drum 42 CPU 43 ROM 44 RAM 46 Position Sensor 51 Operation Unit 56 Timer Counter

Claims (5)

(57) [Claims] 1. A generating means for generating color separation data for forming a color image, and a recording means for sequentially superimposing and recording each color image on an image carrier based on the color separation data generated from the generation means. A color image recording apparatus comprising: a driving unit for rotating the image carrier; and a predetermined portion common to each color of the image carrier for each rotation of the image carrier by the driving unit. a reference signal generating means for generating a reference signal indicating that the position has passed the, measuring means for measuring the generation cycle of the reference signal, the generation cycle <br/> of the reference signal measured by the measuring means setting means for the correction value for correcting set independently for each color separation data of color misregistration based, each color of the output timing of each color separation data based on the correction value set by the setting means Color image recording apparatus characterized by comprising a control means for correcting controlled independently with. 2. The color image recording apparatus according to claim 1, wherein said color image recording apparatus has scanning means for scanning a document, and said control means controls a scanning start timing for each color. 3. The color image recording apparatus according to claim 1, wherein the image carrier is a recording sheet held on a transfer drum. 4. A generating means for generating color separation data for forming a color image, and image forming for sequentially forming each color image on a single photoreceptor based on the color separation data generated from the generating means. Means, and a transfer means for transferring each color image formed on the photoconductor onto a recording medium in a superimposed manner. A driving means for rotating a holding member for holding the recording medium; A reference signal generating means for generating a reference signal indicating that a predetermined portion common to each color has passed a predetermined position; and a tip of the recording medium held by the holding member after the reference signal is generated is at a transfer position. Measuring means for measuring the time to reach each color, and setting for independently setting a color shift amount for each color separation data based on a difference in time for each color measured by the measuring means. A color image recording apparatus comprising: a setting unit; and a control unit that independently corrects and controls the output timing of each of the color separation data for each color based on each color shift amount set by the setting unit. 5. The color image recording apparatus according to claim 4, further comprising a memory for storing the color separation data, wherein the control unit controls a timing of outputting the color separation data from the memory for each color. The color image recording apparatus as described in the above.