JPH09160330A - Color recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain desired color reproduction without causing color smearing, in the case of superimposing/recording color images. SOLUTION: An LED head 13 with both reading and writing functions and a transfer roller 4 being free to switch the polarity are provided in a final image forming station P4 and resist marks formed on a carrying belt 14 by image forming stations P1-P3 are inversely transferred to the photoreceptor 6 of the final image forming station P4 by the switching of the polarity of the transfer roller 4. The inversely transferred resist marks are read by the LED head 13 with both reading and writing functions and a positional deviation, the quantity of inclination, etc., in the image forming stations P1-P3 with respect to the final image forming station P4 are calculated from the resist marks, to automatically correct the color smearing when the color images are superimposed/recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color recording apparatus for forming a color image by sequentially recording images of a plurality of colors on a recording medium.

[0002]

2. Description of the Related Art Conventionally, as a color recording apparatus of this type, a plurality of image forming stations for forming a toner image on a photosensitive member for each color are arranged side by side along an endless conveyor belt and conveyed. There is one in which color toner images are sequentially superposed on a recording medium adsorbed on a belt to form a color image.
That is, the image forming station is provided for each color,
A toner image is formed on each photoconductor by yellow, magenta, cyan, and black toners based on each color image data, and color-based toner images are sequentially formed on the same recording medium line by line. I am recording.

[0003]

In the conventional color recording apparatus, when the recording head is arranged so as to be inclined with respect to the recording medium, when the color images are recorded in an overlapping manner,
There has been a problem that a color shift occurs due to a position shift of an image, and a desired color reproduction cannot be realized. In order to eliminate this, it is necessary to improve the mounting position accuracy of the recording head, etc., and to provide an adjustment mechanism to check the color misregistration amount of the recording result while performing trial and error adjustment work. It was very expensive. In order to solve the above problems, there has been a demand for a color recording apparatus equipped with a low-cost color shift prevention means.

An object of the present invention is to provide a color recording apparatus which realizes a desired color reproduction without causing a color shift when color images are recorded in an overlapping manner.

[0005]

In order to achieve the above object, the color recording apparatus of the present invention is an LE with both reading and writing functions.
A D head and a transfer roller whose polarity can be switched are provided in the final image forming station, and the resist mark formed on the conveyor belt by each image forming station is switched to the final image by switching the polarity of the transfer roller. The resist mark is reversely transferred to the photoconductor of the forming station, and the resist mark thus reversely transferred is read by the LED head having both reading and writing functions.

[0006]

Embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are given the same reference numerals.

FIG. 1 is a perspective view showing the structure of the main part of the present invention, and FIG. 2 is a side view of a color recording apparatus showing an embodiment of the present invention. In the color recording apparatus 1, as shown in FIG. 2, four sets of image forming stations P1 to P4 are sequentially arranged from the insertion side of the recording medium 23 to the discharge side along the conveyor belt 14. The image forming stations P1 to P4 are composed of an electrophotographic LED (light emitting diode) printing mechanism, and the image forming stations P1 to P3 are the same, but the final image forming station P4 is the same. The configuration is slightly different from that of the image forming stations P1 to P3. The image forming stations P1 to P4 are arranged in parallel at a distance L, and the image forming stations P1 to P3 are the image forming unit 2 and the writing L.
The final image forming station P4 is composed of the ED head 3 and the transfer roller 4, and the final image forming station P4 is composed of the image forming section 2, the LED head 13 having both reading and writing functions, and the transfer roller 4.

In each of the image forming sections 2 of the image forming stations P1 to P4, the photoconductor 6 which rotates about the shaft 5 in the direction of the arrow a and the charging roller 7 which uniformly charges the surface of the photoconductor 6 are provided. ,
A developing roller 8, a developing blade 9 and a sponge roller 10 are provided. Each image forming section 2 has a yellow roller.
(Y) Toner-11Y, Magenta (M) Toner-11
M, cyan (C) toner 11C, and black (B) toner 11B are stored. Tona-11Y, 11M,
11C and 11B reach the developing blade 9 through the sponge roller 10, respectively, are thinned on the roller surface of the developing roller 8, and reach the surface of the photoconductor 6. Tona-11Y, 1
1M, 11C, and 11B are strongly rubbed by the developing roller 8 and the developing blade 9 at the time of forming a thin layer, and are triboelectrically charged. The toner used in this embodiment is a non-magnetic single component and is negatively charged by friction. Sponge Roller 10 is a toner
11 is conveyed to the developing blade 9 in an appropriate amount. The developing roller 8 is made of a semiconductive rubber material.

The LED heads 3 and 13 are LED arrays, L
A substrate on which a drive IC for driving the ED array is mounted, L
A selfoc lens array for condensing the light from the ED array, etc., and the LED array is caused to emit light in response to an image data signal input from an interface section described later to expose the surface of the photoconductor 6. , An electrostatic latent image is formed on the surface of the photoconductor 6. Then, the toner on the circumference of the developing roller 8 is attached to the electrostatic latent image by the electrostatic force to form a toner image.

Further, L of the final image forming station P4
The ED head 13 is a toner formed on the surface of the photoconductor 6.
It also has a function of reading an image by irradiating it with a light source 12, and, for example, as disclosed in Japanese Patent Laid-Open No. 58-157252, means for emitting light from an LED array and intensity of light received by the LED array are used. And means for outputting an electric signal accordingly.

Incidentally, L of the image forming stations P1 to P3
LED of ED head 3, final image forming station P4
The head 13 is, in order, a yellow image of the color image signal.
An image signal, a magenta image signal, a cyan image signal, and a black image signal are input.

A conveyor belt 14 is movably arranged between the photoconductor 6 and the transfer roller 4. In this embodiment, the photoreceptor 6 and the transfer roller 4 are brought into contact with the conveyor belt 14. ing. The conveyor belt 14 is made of a high-resistance semiconductive plastic film in an endless shape, and has a driving roller 15
It is also wound around the driven roller 16. Conveyor belt 1
The electrical resistance value of 4 is in a range such that the recording medium 23 can be electrostatically attracted to the conveyor belt 14 and static electricity remaining on the conveyor belt 14 when the recording medium 23 is separated from the conveyor belt 14 can be naturally eliminated. I shall. Drive roller 15
Is connected to a motor to be described later, and this motor rotates the drive roller 15 in the direction of arrow b. Also, the driven roller 1
Guide plates 17 are provided at both ends of the shaft 16a of No. 6 and are pulled in the direction of arrow d by a tension coil spring 18. Thereby, the conveyor belt 14 is always stretched.

The conveyor belt 14 is an image forming station P.
It is passed over between the photoconductors 1 to P4 and the transfer roller 4. A guide roller 1 is provided below the final image forming station P4 with the conveyor belt 14 interposed therebetween.
8 and a cleaning blade 19 are provided. The tip of the cleaning blade 19 made of an elastic material such as flexible rubber or plastic material is pressed against the guide roller 18 and transferred to the conveyor belt 14 by the cleaning blade 19. The toner is scraped off into the waste toner tank 20.

On the right side of the color recording apparatus 1, as shown in FIG. 2, there is provided a paper feed insertion slot 21 into which the operator manually inserts the recording medium 23 into the color recording apparatus 1.
A paper feed tray 22 for the recording medium 23 projects from the paper feed insertion opening 21. The photo sensor 24 detects that the recording medium 23 has been inserted into the paper feed receiving port 22, and each operation of the color recording apparatus 1 is started by this detection. Paper feed roller 2
Reference numeral 5 is a pair of paper feed rollers, and the recording medium 23 is sent to the guides 26 and 27 by the rotation of the paper feed roller 25. Further, the next photo sensor 28 detects the leading edge of the recording medium 23 sent by the paper feed roller 25, and reaches the pair of registration rollers 29. Further, when the registration roller 29 is rotated by a motor described later, the recording medium 23 is guided by the guides 30 and 31,
It is guided to the conveyor belt 14.

A static eliminator 33 is provided on the drive roller 15 side of the conveyor belt 14. The static eliminator 33 is the conveyor belt 1
The recording medium 23 adsorbed and sent to the recording medium 4 is discharged, the adsorbed state is released, and the recording medium 23 is easily separated from the conveyor belt 14.

A guide 34 and a fixing device 35 are provided on the left side of the static eliminator 33. The fixing device 35 is a device for fixing the toner image on the recording medium 23 having the toner image transferred thereon by being conveyed by the conveying belt 14, and a heat roller 36 for heating the toner on the recording medium 23, A pressure roller 37 for pressing the recording medium 23 together with the heater roller 36 is provided. A discharge port 38 is provided on the left side of the fixing device 35, and a discharge stacker 39 is provided outside the discharge port 38.
The printed recording medium 23 is discharged to the discharge stacker 39.

FIG. 3 is a control block diagram of the color recording apparatus shown in FIG. In the figure, reference numerals Y, M,
C and B represent the initials of yellow, magenta, cyan, and black that are color printed by the image forming stations P1 to P4, respectively.

The control circuit 41 comprises a microprocessor or the like and controls the overall operation of the color recording apparatus 1, and also generates various timing signals and the like. The control circuit 41 also stores test pattern data as shown in FIG. The control circuit 41 supplies sponge bias power supplies 42Y, 42M, 42C for supplying electric power to the sponge rollers 10 of the image forming stations P1 to P4.
42B and developing bias power supplies 43Y and 43 for supplying electric power to the developing rollers 8 of the image forming stations P1 to P4.
M, 43C, 43B and image forming stations P1 to P
Charging drum power supply 4 for supplying electric power to each charging roller 7
4Y, 44M, 44C, 44B and transfer power supplies 45Y, 45M, 45C, 45B for supplying electric power for charging the transfer rollers 4 of the image forming stations P1 to P4, respectively.

A developing bias power source 43B and a transfer power source 45B used in the final image forming station P4.
And a polarity changeover switch SW for switching the developing bias voltage supplied to the developing roller 8 and the transfer voltage supplied to the transfer roller 4 to a negative or positive polarity according to an instruction from the control circuit 41. There is.

The control circuit 41 is also connected to a static elimination power source 47 which supplies high voltage electricity for static elimination to the static eliminator 33. Each of the above power supplies is on / off controlled by an instruction from the control circuit 41.

Further, the control circuit 41 is provided with an image forming station.
Print control circuit 48 corresponding to each of the options P1 to P4
Y, 48M, 48C and 48B are connected. The print control circuits 48Y, 48M, 48C and 48B are the memory 49.
Upon receiving image data from Y, 49M, 49C and 49B, these image data are transmitted to the LED heads 3 and 13 according to an instruction from the control circuit 41 to control the exposure time of the LED heads. , Control for forming an electrostatic latent image on the surface of the photoconductor 6 is performed. Memories 49Y, 49M, 49C, 49B
Stores image data sent from an external device via the interface unit 50. The control circuit 41 also controls the memories 49Y, 49M, and 4 through the interface 50.
Image data can be written in 9C and 49B, and the written image data can be read.

The interface unit 50 separates the image data transmitted from an external device, for example, a host computer by color, and stores the yellow image data in the memory 49Y.
The magenta image data is stored in the memory 49M, the cyan image data is stored in the memory 49C, and the black image data is stored in the memory 49B.

The lighting device 46 turns on / off the light source 12 according to an instruction from the control circuit 41. The fuser driver 51 is
A heater (not shown) in the heater roller 36 is driven so as to keep the temperature of the heater roller 36 in the fixing device 35 constant.

The motor drive circuit 52 drives the motors 53 and 54 according to an instruction from the control circuit 41. The motor 53 rotates the paper feed roller 25, the motor 54 is a registration roller 29, the photoconductors 6 of the image forming stations P1 to P4,
The charging roller 7, the developing roller 8, the sponge roller 10, the transfer roller 4, the driving roller 15, and the heater roller 36 are rotated. The rollers rotated by the motor 54 are connected by gears or belts not shown. The sensor receiver driver 55 drives the photosensors 24 and 28, receives the output waveforms of them, and sends them to the control circuit 41.

The amplifier 56 has a final image forming station P.
No. 4, which will be described later, is transferred to the surface of the photoconductor 6.
The output signal of the LED head 13 that has read the image is amplified to a certain level. A / D (analog /
The (digital) converter 57 converts the analog image signal sent from the amplifier 56 into a digital image signal. The binarizing circuit 58 binarizes the image signal sent from the A / D converter 57 with reference to a predetermined threshold level. The binarized image signal is stored in the memory 49B according to an instruction from the control circuit 41. The LED head 13 switches between the writing operation and the reading operation by the signal R / W from the control circuit 41. Further, the control circuit 41 and the memory 49B constitute a deviation / tilt calculation means for calculating a positional deviation amount and an inclination amount between image forming stations, which will be described later.

The test switch 59 is a switch for instructing the start of printing of a test pattern described later.

Next, the operation will be described. First, the operation of printing on the recording medium 23 will be described. When a power source (not shown) of the color recording apparatus 1 is turned on, the control circuit 41 executes a predetermined initialization and then drives the fixing driver 51 to set the heater 36 in the fixing device 35 to a predetermined position. Warm up until the temperature is reached. The control circuit 41 controls the heat roller 36 so that it is always kept at a constant temperature. When the heat roller 36 reaches a predetermined temperature, the control circuit 4
1 drives the motor 54 via the motor drive circuit 52 to rotate the drive roller 15 in the direction of arrow b to move the conveyor belt 14 in the direction of arrow e.

The conveyor belt 14 stops the motor 54 and stops the conveyor belt 14 when the conveyor belt 14 is fed for a little longer than one revolution. As a result, the residual toner and dust adhering to the surface of the conveyor belt 14 are scraped off by the cleaning blade 19 into the waste toner tank 20. Further, the control circuit 41 outputs a signal R / W to the LED head 13 to perform an image writing operation.

As described above, the initialization of the color recording apparatus 1 is completed, and it waits for the image data to be sent from the external apparatus via the interface unit 50.

When the image data sent from the external device, that is, the host computer, is received through the interface section 50, the control circuit 41 causes the interface section 50 and the memories 49Y and 49M to operate. The instruction is output to 49C and 49B. By this instruction, the interface unit 50
Decomposes the received image data signal into yellow, magenta, cyan, and black image data signals and stores them in memories 49Y, 49M, 49C, and 49B.
As a result, the image data of each color for one page printed on the recording medium 23 is stored in the memories 49Y, 49M, 49C and 49B, respectively.

The operation of printing the image data from this state will be briefly described. When the photo sensor 24 turns on,
The control circuit 41 is connected to the motor 5 via the motor drive circuit 52.
3 is driven to rotate the paper feed roller 25. The rotation of the paper feed roller 25 causes the recording medium 23 at the paper feed insertion port 21 to be fed to the guides 26 and 27, and the recording medium 23 is conveyed a little longer than the distance at which the leading end of the recording medium 23 reaches the registration roller 29. Therefore, the motor drive circuit 52 is controlled. As a result, the leading end of the recording medium 23 is rolled by the registration roller 29.
The recording medium 23 is pressed between the rollers and slightly bent, and the skew of the recording medium 23 is corrected by this bending.

Next, the control circuit 41 is connected to the motor drive circuit 52.
The motor 54 is driven through the photosensitive drum 6, the photoconductor 6 of the image forming stations P1 to P4, the charging roller 7, the developing roller 8, the sponge roller 10, and the transfer roller. 4, the drive roller 15, and the heat roller 36 of the fixing device 35 are rotated. At the same time, in order to supply voltage to the charging roller 7, the developing roller 8 and the sponge roller 10 of the image forming stations P1 to P4, the control circuit 4
1 is a charging drum power source 44Y, 44M, 44C,
44B, developing bias power sources 43Y, 43M, 43C, 4
3B, sponge bias power supply 42Y, 42M, 42C,
42B is turned on.

As described above, the image forming stations P1 to P1
The surface of the photoconductor 6 of P4 is uniformly charged (for example, -800 V) through the charging roller 7, and the developing roller 8 and the sponge roller 10 of the image forming stations P1 to P4 are respectively It is charged to -350V and -450V.

Next, the control circuit 41 outputs a command to the memory 49Y which stores the yellow image data, and outputs one line of the yellow image data of the image forming station P1. It is transmitted to the print control circuit 48Y. Print control circuit 4
8Y is a memory 49Y in response to a command from the control circuit 41.
The image data sent from the image forming station P1 is converted into a form that can be sent to the LED head 3 of the image forming station P1.
Send to ED head 3. The LED head 3 turns on the LED corresponding to the sent image data and forms an electrostatic latent image for one line corresponding to the image data on the surface of the charged photoconductor 6. In this manner, the yellow image data sent from the memory 49Y for each line is converted into an electrostatic latent image on the surface of the photoconductor 6 one after another, and one page worth of the yellow image is formed. The data is converted into a latent image and the exposure is completed.

On the surface of the photoconductor 6 on which the electrostatic latent image is formed, a yellow toner is attached from the developing roller 8 by the Coulomb force. As the photoconductor 6 rotates, the electrostatic latent images are developed one after another by the yellow toner. Recording medium 23
When the front end of the transfer roller 4 reaches between the photoconductor 6 and the transfer roller 4, the control circuit 41 turns on the transfer power supply 45Y of the image forming station P1 to charge the transfer roller 4 to + 1500V. . As a result, the toner image on the surface of the photoconductor 6 is
It is electrically transferred onto the recording medium 23 by the transfer roller 4. Here, when a high voltage is applied to the transfer roller 4, the recording medium 23 is attracted to the conveyor belt 14 due to the potential difference from the photoconductor 6.

By rotating the photosensitive member 6, toner images are successively transferred onto the recording medium 23, and a yellow image of one page is transferred onto the recording medium 23. As described above, the transfer of the yellow toner image onto the recording medium 23 by the image forming station P1 is completed. The transport belt 14 continues to move, and the recording medium 23 has an image forming station P.
From 1 to the image forming station P2, a magenta toner image is transferred by the image forming station P2.

The control circuit 41 issues a command to the memory 49M in which the magenta image data is stored, and controls the printing of the magenta image data for one line from the memory 49M in the image forming station P2. Send to circuit 48M. The print control circuit 48M of the image forming station P2 changes the image data sent from the memory 49M to a form which can be sent to the LED head 3 of the image forming station P2 in response to a command from the control circuit 41. And transmits to the LED head 3. The LED head 3 turns on the LED corresponding to the sent image data and forms an electrostatic latent image for one line corresponding to the image data on the surface of the charged photoconductor 6. In this manner, the magenta image data sent from the memory 49M for each line is converted into an electrostatic latent image on the surface of the photoconductor 6 one after another, and the magenta image data for one page is formed. And the exposure is completed. Hereinafter, the operation related to the transfer of magenta is the same as that of the yellow described above, and the description thereof will be omitted.

The recording medium 23 is further moved from the image forming station P2 to the image forming station P3, and then the cyan toner image is transferred by the image forming station P3. When the transfer of the cyan toner image is completed, the recording medium 23 moves from the image forming station P3 to the final image forming station P4, and then the black toner image of the final image forming station P4 is transferred. Transfer is performed.

As described above, the toner images of the respective colors are superimposed and transferred onto the recording medium 23. After that, the recording medium 23 is
It is sent to the static eliminator 33 by the conveyor belt 14, and the control circuit 41 turns on the static eliminator power source 47 to neutralize the recording medium 23. As a result, the recording medium 23 is easily separated from the conveyor belt 14, and the conveyor belt 1 is located above the drive roller 15.
4 is guided to the fixing device 35 by the paper guide 34. When the recording medium 23 separates from the static eliminator 33, the control circuit 41 turns off the static elimination power source.

In the fixing device 35, the heat roller 36 that has already reached a fixing temperature and a pressure roller that is in pressure contact with the heat roller 36.
The toner image is fixed on the recording medium 23 by the roller 37. When the fixing is completed, the recording medium 23 is discharged to the stacker 3
It is discharged to 9. This discharge can be known to the control circuit 41 by the photo sensor 28 detecting the rear end of the recording medium 23.

When the discharge is completed, the control circuit 41 stops the motor 54 via the motor drive circuit 52. In each image forming station, at the time when the trailing edge of the recording medium 23 reaches between the transfer roller 4 and the photoconductor 6, that is, when the transfer of the toner image to the recording medium 23 is completed. , Charging drum power supply, sponge bias power supply, development bias power supply,
The transfer power is turned off.

The printing operation is executed as described above.

When the test switch 59 is turned on, the color recording apparatus 1 starts printing the test pattern. First, the control circuit 41 includes the interface unit 50.
The test pattern stored in the control circuit 41 is written in the memories 49Y, 49M, 49C and 49B via the.
The control circuit 41 includes memories 49Y, 49M, 49C, 49
While transmitting the image data of the test pattern stored in B to the print control unit 48, the test pattern shown in FIG.
Print on page 4. Then, this test pattern is reversely transferred to the photoconductor 6 of the final image forming station P4, and LE
It is read by the D head 13.

The operation of printing the test pattern shown in FIG. 4A and reading the test pattern will be described below with reference to the time chart of FIG.

When the test switch 59 is turned on, the control circuit 41 detects it at time t1, and the LED is output by the signal R / W.
The head 13 is switched to the writing operation. In addition, the test pattern image data stored in the control circuit 41 is stored in the memories 49Y, 49M, as shown in FIG. 6 (b).
It is stored in 49C and 49B.

When the storing operation is completed, the control circuit 41 turns on the respective power supplies as described in the printing operation, and further, as shown in FIG.
As shown in (c), at time t2, the motor 54 is driven via the motor drive circuit 52, and the registration roller 29 and the photoconductors 6 of the image forming stations P1, P2, P3, and P4 are driven. , Charging roller 7, developing roller 8, sponge roller 1
0, the transfer roller 4, the drive roller 15, and the heat roller 36 are rotated.

Next, the control circuit 41 controls the memories 49Y and 49Y.
Test pattern image data from M, 49C, and 49B are output to respective print control circuits 48Y, 48M, 48C, and 48B.
To the LED heads 3 and 13. LED
The heads 3 and 13 are, as shown in FIGS.
An electrostatic latent image is formed on each photoconductor 6 at times t4, t6, t8, and t9. In normal printing, a latent image latent image is formed at the timing shown by the broken line in the figure. That is, the image forming stations P1, P2, P3, and P4 are separated by L lines at equal intervals, as shown in FIG.
The LED head 3 of section P1 drives the first line at time t3, and then the LED head 3 of the image forming station P2 drives the first line at time t5 after the L line, and at time t7 after the L line. Then, the LED head 3 of the image forming station P3 drives the first line. Furthermore, the LED head 13 of the final image forming station P4 drives the first line at time t9, which is L lines after the LED head 3 of the image forming station P3 has driven the first line.

When a test pattern is printed, the LED head 3 of the image forming station P1 starts at time t3 (L).
(p + Lp + Lp) lines at time t4, an electrostatic latent image for Lw lines is formed and developed, and as shown in FIG. 4A, the yellow-colored resist marks 60YL and 60YR move in the direction of arrow e. It is transferred and printed on the left and right of the conveyor belt 14. The latent image, development, and transfer operations are performed in the same way as the printing operation described above. Similarly, the image forming station P
When the LED head 3 of No. 2 develops a latent image for Lw lines at time t6 after (Lp + Lp) lines from time t5 and develops it, as shown in FIG. It is transferred and printed on the right and left sides of the conveyor belt 14 in the e direction.

Further, LE of the image forming station P3
D head 3 is at time t6 after (Lp) lines from time t7.
Then, the latent image for Lw line is formed and developed, and as shown in FIG. 4A, cyan resist marks 60CL and 60C are formed.
R is transferred and printed on the left and right of the conveyor belt 14 in the direction of arrow e. Then, the LED head 13 of the final image forming station P4 forms a latent image for the Lw line at time t9 and is developed, but is not transferred to the conveyor belt 14. That is, the control circuit 41 switches the polarity changeover switch SW of the transfer power supply 45B, so that the control circuit 41 shown in FIG.
As shown in FIG. 5, since -2000V is applied to the transfer roller 4 of the final image forming station P4, the black resist marks 60BL and 60BR on the surface of the photoconductor 6 are transferred to the conveyor belt 14. Without being left on the surface of the photoconductor 6.

Transferring step of final image forming station P4
Since −2000V is applied to the roller 4, the resist marks 60CL and 60C previously transferred to the conveyor belt 14 are used.
R, 60ML, 60MR, 60YL and 60YR are transferred to the transfer roller 4 of the final image forming station P4.
During this transfer operation, as shown in FIG. 5 (i), the control circuit 41 sets L by the signal R / W at time t10 when the resist marks 60BL and 60BR reach the front of the LED head 13.
The ED head 13 is switched to the reading operation. at the same time,
As shown in FIG. 5 (j), the light source 12 passes through the lighting device 46.
Lights up. Also, by turning on the light source 12,
Since the surface voltage of the photoconductor 6 uniformly charged to −800 V drops and the black toner adheres from the developing roller 8, as shown in FIG. 8
At time t11 when the developing roller power source reaches the developing roller 8, the polarity changeover switch SW of the developing bias power source 43B is switched to + 300V to the developing roller 8.
Is applied. Thereby, the resist mark 6 of the photoconductor 6
0CL, 60CR, 60ML, 60MR, 60YL, 6
0YR, 60BL, and 60BR adhere to the developing roller 8 side and are stored in the black toner chamber. Even if the yellow, magenta, and cyan toners are mixed with the black toner, there is no problem in print quality.

The light from the light source 12 applied to the photosensitive member 6 is reflected by the resist mark, read by the LED 13 and photoelectrically converted, passes through the amplifier 56 and the A / D converter 57, and is converted into a binary signal by the binarizing circuit 58. Valued. The control circuit 41 is 2
The output of the digitization circuit 58 is stored in the memory B. When binarizing, a stable value can be obtained by switching the slice level for each color of the resist mark.

When the reading operation is completed, all the power supplies are turned off and the motor is stopped. A part of the toner attached to the conveyor belt 14 is scraped off by the cleaning blade 19 into the waste toner box 20.

By the way, image forming stations P1 to P
If there is no error in the mounting interval L of No. 4 and there is no inclination and they are mounted ideally, each resist mark is shown in FIG.
As shown in (A), the carrier belt 1 is attached to the photoconductor 6 and
4 is transferred. However, in practice, the mounting interval may deviate from the proper position, and the LED heads 3, 13
Etc. may be attached at an angle, so the registration
As shown in FIG. 4B, the marks are displaced and transferred to the conveyor belt 14 or adhere to the photoconductor 6. As described above, all the resist marks are read by the LED head 13 and stored in the memory 49B. The reading range of the LED head 13 is W dots in the main scanning direction and X lines in the sub scanning direction in the range of the broken line in FIG. 4B so that each resist mark can be read completely. LED head 1
Since each element of No. 3 corresponds to the address of the memory 49B in a ratio of 1: 1, the control circuit 41 reads out the image data from the memory 49B through the interface 50, and the register mark It is possible to calculate the positional deviation and the inclination between the resist marks based on any one of them and correct the color deviation when the color images are overlaid and recorded. (Position deviation / tilt correction means) The deviation in the main scanning direction is stored in the memory 49
The leftmost registration mark 60BL, 6 stored in B
It is calculated from 0CL, 60ML, and 60YL. That is, the control circuit 41 determines from the address of the memory 49B, as shown in FIG. 4B, the reference black resist mark 60B.
L is a distance Mb from the leftmost end position of the LED head 13, cyan registration mark 60CL is a distance Mc from the leftmost end position of the LED head 13, and magenta registration mark 60ML is a distance Mm from the leftmost end position of the LED head 13. −
It can be detected that the resist mark 60YL is at the distance My from the leftmost position of the LED head 13.

From this, the positional deviation amount ΔMc of the cyan color (image forming station P3) in the main scanning direction with respect to the black color (final image forming station P4) is (Mb-M
c) and magenta color (image forming station P2)
The amount of positional deviation ΔMm in the main scanning direction is (Mb−Mm), and the amount of positional deviation ΔMy in the main scanning direction of the yellow color (image forming station P1) is (Mb−My). The positional deviation amounts ΔMy, ΔMm, and ΔMc have a sign. When the positional deviation amounts are negative, the positional deviation amounts toward the center side with respect to the final image forming station P4 in the arrow e direction, which is the traveling direction of the conveyor belt. If it is positive, it means that the position is displaced to the outside.

The control circuit 41 gives the positional deviation information to the print control circuits 48Y, 48M and 48C, and the print control circuit 48Y.
Y, 48M, and 48C are the positional deviation amounts ΔMy in the main scanning direction,
The positional deviation amount in the main scanning direction is corrected based on ΔMm and ΔMc.

Next, the displacement and inclination in the sub-scanning direction will be described. First, the control circuit 41 controls the LED head 1
The position shift amount of the resist marks 60CL, 60ML, and 60YL with respect to the resist mark 60BL of the final image forming station P4 is obtained at a position away from the leftmost end of No. 3 by the distance W1. The control circuit 41 controls the registration marks 60BL, 60 located at a distance W1 from the leftmost position of the LED head 13.
By reading the image data at the upper end of CL, 60ML, and 60YL from the memory 49B, it can be known from the address of the memory 49B. That is, the control circuit 41 has the configuration shown in FIG.
As shown in (B), a reference resist mark 60B.
Resist mark 60CL for L, resist mark 6
The distances of 0ML and the resist mark 60YL are
It can be detected that it is Lc1, Lm1, and Ly1.

The position shift in the sub-scanning direction on the right side is the distance W1.
At a position further distant by W2 from the position of, the positional deviation amounts of the resist marks 60CR, 60MR and 60YR with respect to the resist mark 60BR of the final image forming station P4 are similarly obtained. That is, the control circuit 41 is shown in FIG.
As shown in, the resist mark 60CR and the resist mark 60M, which are the reference marks, are used.
The distance between R and the resist mark 60YR is Lc
2, Lm2, Ly2 can be detected.

Further, the control circuit 41 can know the inclinations of the image forming stations P1 to P3 with respect to the final image forming station P4 from the position shift amount in the sub-scanning direction. That is, the image forming stations P1 to P3 are (Ly1 -Ly2), (Lm1 -Lm2), (Lc1) between the final image forming station P4 and the distance W2.
-Lc2) It can be seen that it is tilted. Note that these inclination amounts also have a sign. When the inclination amount is negative, the inclination amount is inclined upward with respect to the final image forming station P4 in the arrow e direction, which is the traveling direction of the conveyor belt, and when the inclination amount is positive, the right shoulder is increased. You are leaning upwards.

As the tilt correction method, for example, if an LED head having a plurality of layers of latch circuits for latching image data for a plurality of lines is used, the control circuit 41 determines the tilt amount and the tilt direction for each print control circuit. It can be easily realized by setting the LED head via 48.

It is obvious that the positional deviation correction in the sub-scanning direction can be easily realized by shifting the drive start timing L of the first line of the LED head 3 as shown in FIG. When the positional deviation in the main scanning direction, the inclination amount and the inclination direction, and the positional deviation in the sub-scanning direction are found, each correction operation is executed, the resist mark is transferred again, and the LED
It is also possible to read the registration mark 60 with the head 13 and confirm each positional deviation amount.

In this embodiment, the writing head is an LED.
Although the head is used, a laser other than the LED head or a liquid crystal shutter may be used.

Further, although the registration mark has been described as a band-shaped one, the consumption of the toner amount is smaller, that is, “╋”, “┏”,
Marks such as “┓”, “┣”, “┳”, “┫” may be used.

Further, the present invention can be applied not only to a four-color image forming station but also to a color recording apparatus having two-color and three-color image forming stations.

Further, although the head having both the reading and writing functions is used alone and has the same length as the printing width, a head slightly longer than the registration mark width may be provided at both ends.

Although the registration mark detection and correction operation is performed by turning on the test switch, the registration mark detection may be automatically performed after the initial setting of the color recording apparatus. Further, it may be performed every time before the printing operation is started. In this case, the test switch is unnecessary.

[0066]

Since the present invention is configured as described above, it has the following effects.

A read / write head and a transfer roller whose polarity can be switched are provided in the final image forming station.
The resist mark formed on the conveyor belt by each image forming station is reverse-transferred to the photoconductor of the final image forming station by switching the polarity of the transfer roller, and the reverse-transferred resist mark is read and written. By reading with the head with a function, the amount of color misregistration can be automatically calculated and these color misregistrations can be automatically corrected, so that color misregistration does not occur in color images and desired color reproduction is realized. it can.

Further, it is necessary to improve the mounting position accuracy of the LED head, the image forming unit, etc., and to provide an expensive adjusting mechanism to check the color misregistration amount of the recording result and perform the adjustment work by trial and error. Since there is no need for adjustment, there is an effect that it is possible to provide a low-cost color recording device that does not require any adjustment.

Further, the toner of the final image forming station
Since the color is black and the color toner other than black constituting the resist mark is mixed with black, the color is black even when printed, and there is an effect that the print quality is not affected.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a main part according to the present invention.

FIG. 2 is a side view of the color recording apparatus showing the embodiment of the invention.

FIG. 3 is a control block diagram of the color recording apparatus shown in FIG.

FIG. 4 is an explanatory diagram of a test pattern.

FIG. 5 is a time chart explaining a test pattern printing operation.

[Explanation of symbols]

 1 Color Recording Device 14 Conveyor Belt P1 to P3 Image Forming Station P4 Final Image Forming Station

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B41J 2/455 B41J 3/21 L 11/42 G03G 15/16

Claims (3)

[Claims] 1. A plurality of image forming stations for forming a toner image for each color on a photoconductor are arranged in parallel along an endless conveyor belt, and toners for each color are sequentially attached to a recording medium adsorbed on the conveyor belt. -In a color recording apparatus that forms a color image by superimposing images, a head with read / write functions and a transfer roller whose polarity can be switched are provided in the final image forming station. The resist mark formed on the conveyor belt is reversely transferred to the photoconductor of the final image forming station by switching the polarity of the transfer roller, and the reversely transferred resist mark is read by the head with both reading and writing functions. A color recording device characterized in that 2. A positional deviation and an inclination amount of the plurality of image forming stations with respect to the final image forming station are calculated from the registration mark information read by the head having both reading and writing functions, and the positional deviation and the inclination amount are calculated. 2. The color recording apparatus according to claim 1, further comprising: a positional deviation / inclination correcting means for correcting positional deviation and inclination of the plurality of image forming stations with respect to the final image forming station based on the amount of inclination. 3. The toner of the final image forming station.
The color recording apparatus according to claim 1, wherein the color is black.