JPS59188663A - Controlling method of copying machine - Google Patents

Abstract

PURPOSE:To always obtain a copy having a good image quality by constituting so that an operation of a part which exerts bad influence on a copying image by a mechanical shock is not executed at the time point when the mechanical shock is generated by a pressure fixing roller. CONSTITUTION:A uniform electrostatic charging and an exposure of an original image are executed to a photosensitive drum 5, an electrostatic latent image is formed on an image area corresponding to a transfer paper, and this latent image is developed with a toner in a developing part, transferred to a transfer paper 11, and pressed and fixed by a pressure fixing roller 19. In this copying operation, after the rear end of the image area on the photosensitive drum 5 against the original image passes through at least a developing part 9, the tip of the transfer paper 11 against its image area is caught by the pressure fixing roller 19, and after the rear end of this transfer paper 11 passes through the pressure fixing roller 19, and the pressure fixation of a toner image in the copying operation is ended, an exposure of an original image in the following copying operation is started.

Description

[Detailed description of the invention] The present invention relates to a method of controlling a copying machine.

Conventionally proposed copying machines uniformly charge a photoreceptor and expose the original image to form an electrostatic latent image in the corresponding image area on the transfer paper, and this electrostatic latent image is passed through a developing section. Develop the toner and transfer the toner image to transfer paper.
After that, some copies are obtained by pressure fixing using a pressure fixing roller G. However, in a copying machine G that uses such a pressure fixing roller, in order to perform good fixing,
When fixing the pressure fixing roller by sandwiching the transfer paper, it is necessary to set G so that the pressure is 500 kg/cm'. Mechanical shocks are generated at the start of fusing when the leading edge of the paper is held in your mouth and at the end of fusing when the trailing edge of the paper is passed through the pressure fixing roller. At the start of fixing, the exposure and development of the original image on the photoreceptor during the copying operation, or when the exposure and development of the original image in the next copying operation are performed at the end of fixing, pressure fixing occurs. There is a drawback that a copy with good image quality cannot be obtained because blurring of the original image and uneven development occur due to the vibration of the optical system and the developing roller caused by the mechanical shock when the rollers come and go.

It is an object of the present invention to provide a copying machine which eliminates the above-mentioned drawbacks and which is capable of consistently producing copies of good image quality even when the pressure fixing roller generates a mechanical shock during its contact and separation. It is intended to provide a control method.

The method for controlling a copying machine of the present invention uniformly charges a photoreceptor and exposes a document image to form an electrostatic latent image in an image area corresponding to a transfer sheet, and transfers this electrostatic latent image to a developing section. After developing the toner, the toner image is transferred onto a transfer paper, and the toner image transferred onto the transfer paper is pressed and fixed by a pressure fixing roller. Is the trailing edge of the image area on the photoreceptor relative to the original image in the image forming area too small? After passing, the leading edge of the transfer paper corresponding to the image area is held in the pressure fixing roller, and the trailing edge of this transfer paper passes through the pressure fixing roller to the transfer paper of the toner image to be subjected to the certain copying operation G. This is characterized in that after the pressure fixing of the original image is completed, exposure of the original image in the next copying operation is started.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an example of a copying machine that implements the control method of the present invention. This copying machine is of a moving original platen type, in which the original placed on the original platen 1 is scanned and exposed while moving the original platen 1, and one copy is obtained from - exposure G of the original image. It is. The document table 1 is provided so as to be reciprocally movable, and a document positioning member 2 for regulating the position of the document placed on the document table 1 is provided at the forward end of the document table 1 . The document placed on the document table 1 is illuminated by an illumination lamp 3, and while the document table 1 is moving forward, its image is transmitted to a photoreceptor drum 5 via a projection optical system 4 consisting of a convergent light transmitting array. image on top.

The photoreceptor drum 5 is rotated in the direction shown by the arrow by a main motor (not shown), and prior to projecting the original image, residual toner is removed from the photoreceptor drum 5 by a cleaning device w6, and a static elimination lamp is applied to the photoreceptor drum 5. After removal of the residual charge by 7G and uniform charging by the corona charger 8, the original image is projected, thereby forming an e-electronic latent image corresponding to the original image on the photosensitive drum 5. The electrostatic latent image formed on the photosensitive drum 5 is developed with toner by a developing device 9, and then the toner image is transferred onto a transfer paper at a transfer section 10&. The developing section W9 uses a dry two-component developer in this example, and is driven by a developing motor (not shown) to rotate the stirring blade 9a to stir the developer, and also rotates the magnetic brush roller 9b to mix the developer. The toner is applied to the photoreceptor drum 5, thereby developing the electrostatic latent image with toner.

On the other hand, transfer papers 11 of the same size are stacked and stored in a cassette 12, and are separated and delivered one by one by rotation of a paper feed roller 13. This fed-out transfer paper is conveyed to the transfer section IO by the registration roller 14 at a timing when its leading edge coincides with the leading edge of the toner image on the photoconductor drum 5 in the transfer section 10G. The toner image on the drum 5 is transferred onto transfer paper. In this example, a corona charger 15 is used as the toner image transfer means, and the corona charger 15 charges the back surface of the transfer paper with a polarity G opposite to that of the toner 4 to transfer the toner image on the photoreceptor drum 5. Transfer onto paper. The transfer paper that has passed through the transfer section 10 is
It is peeled off from the photoreceptor drum 5 by the action G of the peeling corona charger 16 and the peeling claw 17, and is conveyed via the guide 18 to the pressure fixing roller 19, which rotates in conjunction with the rotation of the photoreceptor drum 5 driven by the main motor. , the toner image is fixed on the transfer paper under pressure and is ejected to the copy tray 21 via the ejection roller 20. In this example G, the transfer section 10 is moved from the developing area on the photoreceptor drum 5 by the developing device 9, that is, the area where the magnetic brush roller 9b is closest.
The sum of the circumferential length up to and the length from the transfer section 10 to the pressure fixing roller 19 on the transfer paper conveyance path is configured to be slightly longer than the length of the maximum transfer paper size to be used.

Next, the operation of the copying machine shown in FIG. 1 will be explained.

In this example, the operations of the above-mentioned parts are controlled by a copy start signal generated by the operation of the Coby Star (Nf (not shown)) and by a counter counting the pulses of the pulse generator activated by this copy start signal. The transfer paper size G is selected and controlled by generating timing pulses. Hereinafter, the operation when two copies are successively obtained from one original will be explained with reference to the timing chart shown in FIG.

First, the cleaning device 6 and the static elimination lamp 7 are driven by the fu-hi-star hFt [-ri2 Fig. A) generated by the operation G of the fu-bee start button, and the pulse generator is started to generate pulses of a predetermined period (Fig. 2). B). At the same time, the main morph (Figure 2+C) is driven to rotate the photosensitive drum 5 and the pressure fixing roller 19 (Figure 2D), and the transfer corona charger] 5 (Figure 2E) is driven. do. Next, when the counter that counts the pulses of the pulse generator reaches a predetermined value, the illumination lamp 3 (FIG. 2 F) and the developing motor (FIG. 2 G) are driven, and then the position for cleaning and static electricity removal is performed. When the counter reaches a predetermined count value, the corona charger 8 (Fig. 2H
), the tip of the portion of the photosensitive drum 5 that is uniformly charged by the drive of the corona charger 8 becomes the tip of the original placed on the original platen 1 at the imaging position of the projection optical system 4. At the timing that coincides with the leading edge, place the original platen 1 (Fig. 2■)
start moving forward. Note that the lighting timing of the illumination lamp 8 is determined in consideration of its rise characteristics so that a uniform amount of light can be obtained at the start of exposure of the original. The corona charger 8 charges the selected transfer paper size G after starting the drive.
When the predetermined count value is reached, that is, when the transfer paper and the corresponding image area are uniformly charged, the drive is stopped, and the illumination lamp 3 finishes its forward movement at the predetermined position on the document table 1. The light is turned off in synchronization with , and the driving of the developing motor is stopped after the trailing edge of the image area corresponding to the selected transfer paper G on the sympathetic photosensitive drum 5 passes through the developing section.

At this point, the toner image developed by the toner on the photo drum 5 through the image processing section is transferred to the transfer paper which is conveyed through the registration roller 14 through the transfer section 10G.
This transfer paper is conveyed through the guide 18 to the pressure fixing roller 19&, but the path from the developing section through the entire transfer section 10 to the pressure fixing roller 19& is longer than the length of the maximum transfer paper size to be used. When the leading edge of the transfer paper on which the toner image has been transferred is placed on the pressure fixing roller 19, the exposure and development of the original image corresponding to the transfer paper G have all been completed, and the transfer paper is moved, for example, to the developing motor. After stopping, the toner image is pressure-fixed by passing through a pressure fixing roller 19 for four periods corresponding to the size of the transfer paper indicated by t in the second figure.
The first copy is created. Note that the discharge roller 20 (
In FIG. 2J), the pressure fixing roller 19'fr: rotates from before the leading edge of the transferred transfer paper reaches until the trailing edge passes the discharge roller 20.

The timing at which the trailing edge of the transfer paper onto which the toner image has been transferred passes the pressure fixing roller 19 is determined entirely depending on the selected transfer paper size. Therefore, in this example, the scanning exposure of the original image for the second copy starts after the passing timing, so that illumination is performed at a predetermined count value for each selected transfer paper. A second copy is obtained by controlling the operations of the lamp 3, developing motor, corona charging, container 8, and document table l in the same manner as the first copy operation.

Above, we have explained the operation when two copies are made consecutively from one original, but even more copies can be made.

If you get − consecutively, use the second copy mentioned above.

- Make the movement repeated. In addition, when obtaining copies of different originals in succession (after the trailing edge of the final transfer sheet opposite to the previous original has passed the pressure fixing roller 19), scanning exposure for the next original begins. Then press G to accept the copy start signal for the next document.

Note that the present invention is not limited to the above-mentioned example, and can be modified or changed in many ways.

For example, in winter, the scanning exposure of the original is not limited to the original platen movement method G.
The present invention can also be effectively implemented using an optical system movement method or a document feed method in which only the document is moved.

Further, the transfer corona charger 15 is not necessarily operated all the time during the copying operation, but is only operated when there is transfer paper in the transfer section 10. It is also possible to make it II. Furthermore, although the photoreceptor drum 5, the dry two-component developing device 9, and the transfer corona charger 15 are used in the above-described example, these may be replaced by a photoreceptor belt, a dry two-component developing device, and a circular transfer roller, respectively. Note that when a bias transfer roller is used, the corona charger for peeling] 6 can be omitted. In addition, in this case, since the bias transfer roller comes into pressure contact with the photoconductor through the transfer paper during transfer, even if a mechanical impact occurs on the pressure fixing roller 19 during this transfer period, the transfer effect will have a negative impact. Although it does not extend the length of the transfer paper, it is preferable that the length of the transfer paper conveyance path from the transfer unit 10 to the pressure fixing roller 19 is slightly longer than the length of the maximum transfer paper size, so that the G-force fixing roller 19 is used during the transfer period. It is best to prevent mechanical shock from occurring. Furthermore, a detector for detecting the trailing edge of the transfer paper is provided on the downstream side of the pressure fixing roller 19 in the transfer direction of the transfer paper, and the next copying operation is started based on the output of this detector. You can also do it.

Furthermore, the pressure fixing roller 19 may be rotated by a motor separate from the main motor that rotates the photosensitive drum 5.

As described above, in the present invention, at the time when a mechanical shock occurs in the pressure fixing roller, the parts that have a negative effect on the copy image G due to the mechanical shock are not operated. Copies with good image quality can always be stably obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an example of a copying machine that implements the control method of the present invention, and FIG. 1... Original table 2... Original positioning member 8... Illumination lamp 4... Projection optical system 5...
・Photosensitive drum 6...Cleaning device 7...
- Static elimination lamp 8...Corona charger 9...Developing device 10...Transfer section, 1]...Transfer paper 12...Cassette 18...Paper feed roller ]4...Registration roller 15 ...Corona charger for transfer]6...Corona band part for peeling; container]7...Peeling claw 18...Guide j9.
...Pressure fixing roller 20...Discharge roller 21...
·tray.

Claims (1)

[Claims] 1. After uniformly charging the photoreceptor and exposing the original image to form an image in the image area G'FM,m corresponding to the transfer paper, and developing this electrostatic latent image with toner through a developing section,
The toner image is transferred onto transfer paper, and the toner image transferred onto the transfer paper is pressed and fixed by a pressure fixing roller. A copy is obtained by performing a copying operation. After the trailing edge of the image area on the body has passed through the developing section, the leading edge of the transfer paper corresponding to the image on the body is held in the pressure fixing roller, and the trailing edge of the transfer paper passes through the pressure fixing roller. After pressure fixing of the toner image on the transfer paper in the above-described one copying operation is completed, exposure of the original image in the next copying operation is started? Characteristic copying machine control method.