JPH0442672B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention enables multiple transfer by accurately setting the exposure position on a photoreceptor by stopping a color separation filter at a reference position and then displacing it according to the amount of correction. The present invention relates to a color recording device that prevents image shift.

(Prior Art) Conventional color copying machines, for example, scan the document surface multiple times (for example, three times corresponding to the three primary colors of red, green, and blue), perform the same number of charging steps, exposure steps, development steps, and so on. Some printers obtain a transferred image through a transfer process and then fix it to obtain a single color copy. This color copying machine is equipped with mechanical synchronization means such as a cam to synchronize the operations of the scanning system, photosensitive drum, and transfer drum, and this prevents overlapping deviations in multiple transferred images. I'm trying to prevent it from happening.

However, in conventional color copying machines, the scanning system, photosensitive drum, and transfer drum are synchronized using mechanical synchronization means such as cams, which makes the structure of the device itself complicated. As a result, it becomes difficult to maintain constant accuracy due to mechanical play and the like. Furthermore, since the scanning speed must be changed when changing the magnification, there is a problem that the apparatus becomes even more complicated and larger.

(Objects and Structure of the Invention) The present invention has been made in view of the above, and in order to accurately prevent the shift of the weight of the transferred image without complicating or increasing the size of the device, it is possible to change the position of the scanning system. is corrected by the displacement of the color separation filter, and during this correction, after displacing the color separation filter by a predetermined displacement amount (larger than the fine adjustment displacement amount) from the position of the previous color separation operation, To provide an exposure position control device for a color copying machine, which stops a color separation filter for a subsequent color separation operation at a predetermined reference position, and then displaces the color separation filter in accordance with a correction amount. .

Hereinafter, the color recording apparatus according to the present invention will be explained in detail.

(Embodiment) Figures 1 and 2 A, B, and C show an embodiment of the present invention, in which a platen 2 on which a document 1 is placed is provided at the top of the copying machine, and a platen 2 on which the document 1 is placed at the bottom. A scanning system 4 for scanning is provided. The scanning system 4 includes a light source lamp 4a, mirrors 4b, 4c, 4d, 4e, a lens 4f, and a color separation filter 6. The color separation filter 6 has green, blue, and red filters 5a, 5b, and 5c arranged at intervals of 120°C on a shaft 6a, and one end of the shaft 6a is connected to a belt 8 that transmits the drive of a step motor 7.
It is linked with the step motor 7. An actuator 10 is installed at the tip of each filter 5a, 5b, 5c.
When one of the actuators 10c, 10d, and 10e engages with a photosensor 9 consisting of a light emitting diode and a phototransistor, a position signal for that filter is generated. In addition, the light source lamp 4a and the mirror 4
b (It is placed on the carriage 5. As is clear from FIG.
A photosensor 12 consisting of b is fixed. Further, a photosensitive drum 13 that is exposed to scanning light is provided below the scanning system 4, and is in contact with the transfer drum 14 at a transfer portion 13a. The transfer drum 14 is
As shown in FIG. 2B, a sensor actuator 10b is provided on the outer periphery, and a photo sensor 17 consisting of a light emitting diode 17a and a phototransistor 17b is provided.
A command signal for instructing the start of calculation of the number of pulses, which will be described later, is output. In addition, the transfer drum 14
A pulse generator 16 is provided on the drive shaft 15 . In addition to the above configuration, the transfer section 13
A paper feed tray 18 for supplying copy paper 17 to the photosensitive drum 13 is provided, and a charging corotron 19, an exposure slit 20, and a developing section 21 (for developing the electrostatic latent image on the photosensitive drum 13) are provided around the photosensitive drum 13. A cleaner 22 is provided for removing toner from the photosensitive drum 13 after the toner has been transferred. Furthermore,
A transport belt 23 and a fixing section 24 are provided downstream of the transfer section 13a, and a control section 2 for controlling the operation thereof is provided at a predetermined position inside the copying machine.
9 (for example, a microcomputer). The control unit 29 controls various sensors (photo sensor 1) inside the copying machine.
2 and 17) or operation command signals from a console (not shown); and a ROM 29b that stores programs necessary for arithmetic processing of input signals.
and a CPU that performs predetermined calculations based on the program.
29c and temporarily stores calculation results and data.
It has an output interface 29e that outputs control signals to various control objects of the copying machine (including the step motor 7) or to a display section of a console (not shown) based on the RAM 29d and calculation results.

To explain the operation in the above configuration,
After placing the original 1 on the platen 2, when a start key (not shown) of a console (not shown) is turned on, the scanning system 4 scans the original under the control of the control unit 29. During the first document scanning, the green filter 5a of the color separation filter 6 is placed in the optical path,
The photosensitive drum 13 is exposed to the green component in the scanning light. The latent image caused by the exposure is transferred to the developing section 2.
1a is developed with magenta toner, and this developed image is fed from the paper feed tray 18 and transferred to the transfer drum 14.
The copy paper 17 gripped by the copy paper 17 is transferred at the transfer section 13a. After that, when the second document scan is performed, the blue filter 5b of the color separation filter 6 is placed in the optical path, and the photosensitive drum 13 is exposed to the blue component of the scanning light. The developing section 21b develops the latent image resulting from the exposure using yellow toner, and the developed image is transferred to the copy paper 17 held by the transfer drum 14 at the transfer section 13a. Finally, when the third document scan is performed, the red filter 5c of the color separation filter 6 is placed in the optical path, and the photosensitive drum 13 is exposed to the red component of the scanning light. A latent image based on this exposure is transferred to the developing section 21.
c is developed with cyan toner, and the developed image is applied to the copy paper 17 which is still held by the transfer drum 14.
is the last to be transcribed.

The color separation filter 6 is shown below in Figure 3 A, B, and C.
The control will be explained in detail. FIG. 3A shows a case where the transfer drum and photosensitive drum of the scanning system are synchronized. Before starting document scanning, transfer drum 1
4 rotates together with the photosensitive drum 13, the sensor actuator 1 provided on the transfer drum 14
0b blocks the light from the light emitting diode 17a and turns on the photosensor 17 (time t ₁ ). As a result, a pulse detection start signal is input to the control unit 29,
The pulse signals of the pulse generator 16 are counted. Next, when the scanning system 4 has scanned a certain distance, the sensor actuator 10a provided at one end of the carriage 5 switches on the light emitting diode 12a.
The photo sensor 12 is turned on (time t ₂ ). By turning on the photosensor 12, the control unit 2
9 finishes counting the pulse signals, compares the counted value n with a predetermined value N, and based on the determination that N=n, no control signal is output. Therefore, the color separation filter 6 that exposes the filters 5a, 5b, and 5c to the optical path does not receive a displacement command for color misregistration correction. Next, FIG. 3B shows a case where the scanning system is ahead of schedule. Prior to the start of document scanning, when the transfer drum 14 rotates, the photosensor 1
7 starts counting pulse signals,
When the photosensor 12 is turned on, counting of pulse signals is terminated. The control unit 29 compares the count value k with a predetermined value N, and since k<N, outputs a control signal according to the difference of N-K, rotates the step motor 33 clockwise, and rotates the step motor 33 via the belt 8. The filter 5a, 5b, or 5c that is exposed in the optical path of the color separation filter 6 is rotated clockwise by a predetermined displacement amount from a reference position (described later) (based on a positive control signal). FIG. 3C shows a case where the scanning system 4 is behind schedule, and since P>N when comparing the count value P and a predetermined value N, the color separation filter 6
The filter 5a, 5b, or 5c that is exposed in the optical path is rotated counterclockwise by a predetermined displacement amount from the reference position (based on a negative control signal). As is clear from the above description, the filters 5a, 5b, or 5c are displaced clockwise or counterclockwise by an angle θ to correct delays or excessive scan advances and prevent image shifts from occurring. Photosensitive drum 13
The correction amount x of the upper image shift is determined by the color separation filters 5a, 5.
It is determined from the correction angle θ of displacement from the reference position of b and 5c and the thickness t of the filter. The relationships among x, θ, and t are shown in Figure 4 A and B. The refractive index of the air in the optical path is
When n ₀ and the refractive index in the color separation filters 5a, 5b, and 5c are n ₁ , the correction amount x is determined from x=t1/cos θ·sin (θ−θ′). θ′ in the above equation is determined from θ′=sin ⁻¹ (n ₀ /n ₁ ·sin θ).

This x corresponds to the deviation that occurs between the incident position and exit position of the color separation filter 5a, 5b, or 5c due to the correction angle θ displacement of the color separation filter 5a, 5b, or 5c from the reference position, and the scanning system 4 and the photosensitive drum 13 or transfer drum 14
Image shift can be prevented by selecting the correction angle θ according to the positional variation between the two images. The color separation filters 5a, 5b, and 5c are configured to be rotationally driven by a step motor 7, and are rotated by a displacement amount corresponding to the above-mentioned pulse number count from a stopped reference position.

After the filter 6 is rotated by a predetermined displacement angle (for example, 120°C - θ _M , θ _M is the maximum correction displacement angle) for each scan, the color of the subsequent color separation operation is determined based on the operation of the photosensor 9. When it is detected that the color separation filter has passed the photo sensor 9, the color separation filter is stopped. This stop position is the reference position,
It is displaced from this reference position by an amount of displacement corresponding to the count value of the number of pulses described above.

Below, the operation to control this amount of displacement will be explained as shown in Fig. 5A.
This will be explained in more detail. Assume that exposure is now being performed using the filter 5a. When the scanning system 4 finishes scanning the document surface and enters the return operation (area a in Fig. 5A), the filter 6 rotates clockwise by the aforementioned displacement angle (120°C - θ _M ) (the 5th In region (1) of FIG. 5B, the sensor actuator 10d stops when it enters the optical path and the sensor actuator 10d passes the photosensor 9 (region () of FIG. 5B). This stop position is a reference position, and fine adjustment movement is performed from this reference position to a corrected displacement position based on the pulse count value. In FIG. 5B, C is a fine adjustment movement in the counterclockwise direction, and D is a fine adjustment movement in a clockwise direction. Here, the movement amount of B is larger than the movement amount of A because the fine adjustment movement of C is counterclockwise. It is based on an increase in quantity.

The movement of the color separation filter is controlled by rotating the color separation filter by a predetermined angle within a range that does not exceed the position detection means, then moving the color separation filter to the reference position, and then moving the color separation filter to the photoconductor/transfer body and scanning. Compensation control for synchronization deviation with the system is performed, so the color separation filters do not overrun the reference position, and the color separation filters can arrive at the reference position at low speed. The arrival time of the color separation filters required from the position of the color separation filters determined by the color separation filter to the specific position of the color separation filters determined by the next color separation operation can be shortened. At the same time, the accuracy of stopping the color separation filter can be improved.

〔Effect of the invention〕

As explained above, according to the color recording apparatus according to the present invention, the variation in the position of the scanning system is corrected by the displacement of the color separation filter. After displacing the color separation filter by a predetermined displacement amount (larger than the fine adjustment displacement amount) from the position, the color separation filter for the subsequent color separation operation is stopped at a predetermined reference position,
Next, since the color separation filter is displaced in accordance with the amount of correction, it is possible to accurately prevent the shift of the weights of multiple transfer images without complicating or increasing the size.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the structure of a color recording apparatus according to the present invention. FIG. 2A is an explanatory diagram showing a scanning system and a photosensor. FIG. 2B is an explanatory diagram showing a sensor actuator provided on the transfer drum and a photo sensor provided on the outer periphery of the transfer drum. FIG. 2C is an explanatory diagram showing a color separation filter and a step motor. Third
Figures I to C are time charts showing the operations. FIGS. 4A and 4B are explanatory diagrams showing the relationship between the amount of rotation of the mirror and the amount of correction of the incident position of the photosensitive drum. Figures 5A and 5B are time charts showing the operation of the scanning system and filter. Explanation of symbols 1... Original, 2... Platen, 4...
... Scanning system, 6 ... Color separation filter, 7 ... Step motor, 9 ... Photo sensor, 12 ... Photo sensor, 13 ... Photosensitive drum, 14 ... Transfer drum,
17...Photo sensor, 21...Developing section.

Claims (1)

[Claims] 1. Exposure for each color of color-separated document information;
In a color recording device that overlaps each step of development and transfer, there is a means for outputting a reference timing signal when the transfer means or photoreceptor reaches a predetermined position, and a means for outputting a reference timing signal when the reference timing signal is output, depending on the position of the scanning system. a means for outputting a position signal according to the color separation; a plurality of color separation filters provided according to the number of color separations; a moving means for displacing the color separation filter in order to change the incident angle of the light beam to the color separation filter; means for calculating the amount of displacement of the color separation filter by the moving means from the reference timing signal and the position signal; and control means for moving the color separation filter by the moving means in accordance with the calculation result of the calculating means. A color recording device characterized by: 2. The moving means rotationally moves the color separation filter, and includes position detection means for the color separation filter provided at a common reference position for each of the rotating color separation filters, and the control means is configured to rotate the color separation filter. From the position of the color separation filter determined by the color separation operation, the color separation filter is rotated by a predetermined angle that does not exceed the position detection means when viewed in the rotational direction of the color separation filter, and then the color separation filter is 2. The color recording apparatus according to claim 1, wherein after the color separation filter is moved to the reference position, movement of the color separation filter is controlled according to the calculation result of the calculation means.