JPS60218673A - Color copying machine - Google Patents

Abstract

PURPOSE:To obtain a color copying machine where the printing work is advanced efficiently, by fixing a proper print time corresponding to the size of a recording form. CONSTITUTION:Servo motors 200, 210, and 220 are connected to respective shafts 20 and 21 of a photosensitive drum 6 and a transfer drum 11 and a capstan shaft 22 of a scan mechanism system. A control part of a device is provided with a reference pulse circuit 25 which supplies reference pulses for uniform- speed rotation of the servo motor 200, servo circuits 26 and 27 which drive and control servo motors 210 and 220, and a paper size setting circuit 28 which sets the size of the recording form to servo circuits 26 and 27. Only the servo motor 220 connected to the capstan shaft 22 can be rotated forward and reverse.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color electronic copying machine capable of obtaining a recording speed corresponding to the size of recording paper.

[Prior art]

FIG. 1 is a side view showing an example of the configuration of a conventional general color copying machine.
~35, a scanning exposure system consisting of a focusing lens 4, a three-color separation filter 5, a photosensitive drum 6, and different colors of yellow, magenta, and cyan (hereinafter referred to as Y) successively arranged on the circumferential surface of the photosensitive drum 60.

Developing machine 7.8 that accommodates toner of each color (abbreviated as M, C)
．． Developing system consisting of 9, grits that grip the recording paper and 1
0, a transfer system consisting of a transfer corotron 12 installed inside the transfer drum 11, and paper feed trays 13, 14 . It is configured to include a paper feeding system consisting of a paper feeding roller 15, a fixing/discharging system consisting of an endless conveyor belt 16, a fixing roller 17, a paper discharging roller 18, and a paper discharging tray 19. Also, Figure 2 (a
).

(b) and (c) are timing charts showing the operations of each part of the scan exposure system, development system, and transfer system in the conventional apparatus, respectively. When a recording start operation is performed in FIGS. 1 and 2, the light source lamp D25 reflecting mirrors 30, 31, 32 are scanned back and forth three times from time t0, and the image on the photosensitive drum 6 is displayed at the time of each scan. Said 3 interposed tenth in the scanning optical path
Exposure is performed through the blue, green, and red filters of the color separation filter 5 (see FIG. 2(, )). The electrostatic latent image of each color component image information formed on the photosensitive drum 6 by this three-color separation exposure is developed by opposing complementary color toners Y, M, and C8C when passing through the development system, and the exposure starts. At time t1 after a certain period of time has passed from time 1o, these Y
, M, C) The leading edge of the toner image sequentially reaches the transfer position T where the photosensitive drum 6 and the transfer drum 11 are in contact (FIG. 2(b)
reference). On the other hand, the transfer drum 11 is also rotated at the same circumferential speed as the photosensitive drum 6 from the start of the exposure, and is rotated while gripping the recording paper of a predetermined size supplied from the paper feed system at a grip of /f10 for the time period mentioned above. At tl, the leading edge of the recording paper is also conveyed to the transfer position T (see FIG. 2(C)). After that, the photosensitive drum 6 and the transfer drum 1
1 at the same circumferential speed, the above operation is repeated three times, and the Y, M, and C toner images formed on the photosensitive drum 6 are sequentially transferred from the same position each time to the recording paper. , M, C) color copies were obtained by mixing them. The inside of Figure 2 shows the photosensitive drum 6 and the transfer drum 1.
The length corresponds to the circumference of 1. Like this Y, M, C
In a device that sequentially transfers each toner image onto a recording sheet and obtains a color copy by mixing them, a scan drive system, a photosensitive drum 6, and a transfer drum 11 are used to prevent misalignment of the transfer positions and improve the print quality. It is important to synchronize the drives. In this respect, in the past, the photosensitive drum 6 and the transfer drum 11 were connected by gears with low discrepancy and driven together, and the scan drive system was driven by a serve motor or the like that was highly responsive to speed control. A method has been used to increase the accuracy of the synchronization. As an example of selecting the circumferential length of the transfer drum 11 based on such a driving method, a length corresponding to the scanning reciprocating time of the maximum size A3 recording paper is used, or a length equivalent to the maximum size A3 recording paper is used. There are two possible methods: using one with a certain length,
In any case, based on the above dispute, the transfer drum 1
Since the circumferential speed of No. 1 depends on the circumferential speed of the photosensitive drum 6 and is constant, in the former method of selecting the transfer drum circumference described above, B
The recording speed is the same for B5 to A3 sizes, and in the latter case, it is necessary to regenerate the transfer drum 11 once during scano pack when recording A3 size. It had the disadvantage that it required approximately twice the recording time as A4 size.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a color copying machine that can establish an appropriate printing time depending on the size of small recording paper and can efficiently proceed with printing work.

[Structure of the invention]

Therefore, in the present invention, scanning and scan packing are carried out in an amount corresponding to the paper size for each color component, and the developed toner image of the electrostatic latent image of each color component formed on the photosensitive drum is transferred by the scanning. During transfer, the rotational speed of the transfer drum is varied according to the paper size so that the leading edge of the toner image of the next color and the leading edge of the recording paper coincide at the transfer position, so that the rotational speed of the transfer drum is adjusted according to the paper size. [Embodiment] Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings. FIG. 3 is a schematic diagram of a color copying machine showing an embodiment of the present invention, and parts corresponding to those of the conventional apparatus shown in FIG. 1 are designated by the same reference numerals. According to the apparatus of the present invention shown in FIG. 3, independent servo motors 200 and 210 are used for each of the rotating shafts 20 and 21 of the photosensitive drum 6 and the transfer drum 11 and the cab stun shaft 22 that drives the scanning mechanism system. , 220 are connected.

Here, only the servo motor 220 connected to the cab stan shaft 22 is capable of forward and reverse rotation.

Further, the vicinity of the waiting position of the light source rung 2 before the start of scanning in the scanning mechanism system and the above-mentioned transfer position T
Optical sensors 23 and 24 are disposed near the circumferential surface of the transfer drum 11 immediately in front of the transfer drum 11 to detect the scan start timing and the trailing edge of the transfer recording paper, respectively.

Further, the control unit of this device includes a reference pulse circuit 25 that provides a basic pulse to rotate the servo motor 200 at a constant speed,
0 drive 11i1] servo circuits 26 and 27,
A paper size setting circuit 28 is configured to issue a recording paper size command to the servo circuits 26 and 27. Furthermore, Fig. 4 (a), (b), (e).

<tf) and (e) are the scanning mechanism, sensor 23, photosensitive drum 6, and transfer drum 11 in the above device, respectively.
, and is a timing chart showing each operation of the sensor 24.The control operation of the apparatus of the present invention will be described in detail below with reference to FIG.

In the figure, t and R correspond to the circumferential length of the photosensitive drum 6 and the transfer drum 11, the recording paper length, and the scan pack length, respectively.

First, prior to the printing operation, the paper size setting circuit 28 is set with the size of the recording paper used for the printing, and a paper size signal based on the setting is sent to the surging circuits 26 and 27.
is input. Next, when a recording start operation is performed, the reference pulse circuit 25 sends the reference pulse 4 to the servo motor 200.
The servo motor 200 rotates the transfer drum 6 at a constant circumferential speed based on the reference pulse. The rotation signal of this servo motor 200 is input to the servo circuit 27, and the servo circuit 27 uses this rotation signal and the paper size signal input from the paper size setting circuit 28 as described above. The servo motor 220 is driven forward to scan a length corresponding to the paper size (corresponding to time t1), and then reversed to perform scan pack at a preset degree of rotation (time t1).
2).

The above scanning operation is performed on the one placed on the grating L.
This is repeated for each of the three-color separation filters 17, green, and red filters sequentially interposed in the scanning optical path for a sheet of color original, and the three-color image information of each color component is printed on the photoreceptor drum 6. Perform decomposition exposure (see Figure 4 (,))
. The scan operation at this time is that instead of waiting for the photosensitive drum 6 to complete one revolution and then starting the scan from the same position for each color component as in the conventional case, the next scan starts immediately after the scan pack is completed. Ru. At the start of scanning for each color component for such three-color separation exposure, the start of scanning is detected by the sensor 23 according to the movement of the light source run f2 (see FIG. 4(b)), and the detection output is The signal is input to the servo circuit 26. Next, when the electrostatic latent image of each color component image information formed on the photosensitive drum 6 by the three-color separation exposure passes through the above-mentioned developing section, it is transferred to the developing devices 7, 8. Toner Y, M
, C sequentially. Through this operation, the leading edge of the Y toner image developed first comes into contact with the transfer drum 11 after a certain period of time t3 corresponding to the circumferential speed of the photoreceptor drum 6 has elapsed from the scan start time to of the blue component image information. It reaches position T (see Figure 4(c)). On the other hand, the above? The circuit 26 also connects the motor 200 as described above.
In response to the rotation signal, the servo motor 210 is driven to rotate the transfer drum 11 at the same circumferential speed as the photosensitive drum 6, and during the rotation, the gripper 10 picks up the recording paper fed from the paper feed system. When a time t3 has elapsed from the first scan start time to, conveyance control is performed such that its leading edge meets the leading edge of the Y toner image at the transfer position T (see FIG. 4(d)).

From this transfer position, the transfer of the Y toner image formed on the photosensitive drum 6 onto the recording paper that is conveyed in close contact with the transfer drum 11 is started.

The transfer of the Y toner image is completed at time t6 by rotating the photosensitive drum 6 and the transfer drum at the same circumferential speed and conveying the recording paper length t, but at time t4 just before the transfer ends, the recording is completed at time t4. The trailing edge of the paper is detected by the sensor 24 (see FIG. 4), and the detection signal is input to the servo circuit 26. Therefore, the servo circuit 26 counts the time t5 required for conveying the recording paper from the sensor 24 placement position to the transfer position Ti from the trailing edge detection signal input time t4, thereby obtaining the above-mentioned transfer end time t6. is detected, and from this time t6, the rotation speed of the servo motor 210 is changed and driven according to the paper size signal. The leading edge of the M toner image that is formed on the image and reaches the transfer position T and this transfer position T
The speed is controlled so as to comply with the above (see Fig. 4(d)). That is, as is clear from FIGS. 4(c) and 4(d), the photosensitive drum 6 advances the distance R from the Y toner image transfer end time t6 to the M toner image to be formed next, that is, at time t7. In the transfer drum 11, it is necessary to advance the difference between the circumferential length and the recording paper length t, that is, (L, t). Now, if the rotational speeds of the photosensitive drum 6 and the transfer drum 11 at the time of rapid rotation are V6 and vl, respectively, the above conditions are met. Therefore, when formula (1) is rearranged, the transfer drum 11 is given a rapid rotation speed vl as follows.

In the above equation (2), the peripheral speed V of the photosensitive drum 6.

Since the paper length t of the recording paper and the amount of rotation R during scan pack can be recognized by the paper size signal given from the paper size setting circuit 27, the rotating ram 11 can be driven at a rotational speed suitable for the paper size. Incidentally, the servo circuit 26 changes the above-mentioned magnetic field v1 from the time t6 as in the first scanning operation via the blue filter.
The transfer drum 11 rotated by the sensor 23
For the second time, that is, when time t1 is counted after the scan start detection signal via the green filter is input, rotation control is performed to return the speed v1 to the normal speed V6.

From this time, that is, time t8, the transfer drum 1
Transfer of the M toner image onto the recording paper conveyed by 1 starts. Thereafter, the servo circuit 26 operates between the transfers determined by the transfer end time detected from the trailing edge detection signal of the recording paper by the sensor 24 and the transfer start time detected from the scan start detection signal by the sensor 23, as described above. By rapidly rotating the transfer drum 11 at a speed v1, the leading edge of the C toner image and the leading edge of the paper coincide with each other at the transfer position, and from there, by rotating the drum 11 at a speed vo, the C toner image is also transferred. The desired color reproduction is completed by crystallization of the C toner.

Results of such rotational speed control of the transfer drum 11 (5) Compared to the conventional printing time, each color toner image is transferred at a circumferential speed of 16 (
L-7) and ordinary time t9, that is, t
9=The printing time of only L-1-R can be reduced. In addition, on the upper side, the circumferential length of the transfer drum 11 is the length equivalent to the scanning reciprocating time of the maximum size recording paper, and when the paper size is the maximum, the transfer drum 1
In the above example, the transfer drum 11 is always rotated at a constant speed v6 to execute printing and rotated quickly at a speed Vl between transfers only when the paper size is smaller than this. Select the transfer drum 1 that is smaller than the scanning reciprocating time of the maximum size recording paper.
Similarly to the above, even if the printing speed is set to be faster or slower between transfers depending on the paper size, it is possible to obtain a recording time corresponding to the paper size as described above.

〔Effect of the invention〕

As explained above, according to the color copying machine of the present invention, scanning and scan packing are performed for each color component according to the paper size, and during the scanning, the color components on the formed photoreceptor drum are scanned and packed according to the paper size. The rotational speed of the transfer drum is varied according to the paper size so that the leading edge of the next toner image and the leading edge of the recording paper coincide at the transfer position between each transfer of the developing toner image of the electrostatic latent image. As a result, an appropriate recording speed corresponding to the paper size can be obtained, and an efficient printing operation can be performed.

[Brief explanation of the drawing]

Figure 1 is a side view showing the configuration of a conventional color copying machine.
The figure is a timing chart showing the operation of each part in this conventional device, FIG. 3 is a conceptual configuration diagram of a color copying machine showing an embodiment of the present invention, and FIG. 4 is a timing chart showing the operation of each part in this inventive device. It is a chart. 6... Photosensitive drum, 11... Transfer drum, 20°2
1 * 22... Rotating axis, 200.210.220.
... Servo motor, 23.24 ... Optical sensor, 25
...Reference pulse circuit, 26.27...Servo circuit,
28...Paper size setting circuit.

Claims (1)

[Claims] A color original is sequentially exposed to multiple color separations on a photosensitive drum rotated at a constant speed by repeated scanning with a scanning optical system, and after being developed with opposing complementary color toner each time, it is brought into contact with the photosensitive drum. In a color copying machine that obtains a color copy by repeatedly transferring images onto a recording paper on a transfer drum that is rotated by the user, the color copying machine includes a first sensor that detects the start of scanning of the scanning optical system, and a first sensor that detects the start of scanning of the scanning optical system; and a second sensor for detecting, and detects the transfer start time and transfer end time from the detection outputs of the first and second sensors, and also detects the transfer start time and transfer end time on the transfer drum between the detected end and start of transfer. 1. A color copying machine comprising: control means for variably controlling the rotational speed of the transfer drum so as to align the leading edge of the recording paper with the leading edge of the toner group of each color.