JPH027473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the removal of optical memory from a photoreceptor when the photoreceptor is exposed to external light in an electrophotographic copying machine whose main body is configured to be separable into upper and lower parts.

According to electrophotographic copying machines, images may gradually become blurred due to fatigue of the photoreceptor. In other words, due to fatigue of the photoreceptor, the image density differs between the first and second sheets, and the image density becomes stable after the third sheet. Therefore, when copying is performed, prior to image formation by the start of copying, the photoreceptor is rotated idly to charge and remove electricity, and after the photoreceptor is fatigued to a stable state, image formation is started. For example, Japanese Patent Application Laid-Open No. 54-105553 discloses that in an apparatus for forming an image on a photoreceptor, prior to image formation, a pretreatment process is performed in which the photoreceptor is rotated to fatigue the photoreceptor to a predetermined state. , it is specified that image formation is initiated.

Furthermore, in the electrophotographic copying machine as described above,
When cleaning copy paper jams, cleaning areas contaminated with developer, or replacing or repairing other consumable parts such as the photoconductor, open the front door of the copier and reach the back of the machine. I had to put it in there and process it.

Alternatively, it has sometimes been necessary to remove the rear or upper exterior, and sometimes even unrelated parts within the main body. Recently, a copying machine has appeared in which the main body of the copying machine can be separated vertically from one end along the copying machine feeding/conveying path, and it has become possible to considerably alleviate the above-mentioned difficulties.

However, since separation is possible in this manner, the photoreceptor is exposed to external light during separation, resulting in a large change in the characteristics of the portion of the photoreceptor exposed to the light. Therefore, when the separated upper and lower parts of the copying machine main body are closed again to make a copy, an optical memory effect occurs, causing a problem. For example, because there is not enough charge on the photoreceptor, the first few copies may appear white, especially in areas corresponding to parts of the photoreceptor exposed to external light.
This may cause adverse effects such as the color of the formed image becoming dull.

In particular, when a user encounters a paper jam, separates the top and bottom of such a copying machine, removes the jammed paper, closes it again, and makes a copy, the user is unable to output blank copy paper. This would be extremely inconvenient for them. Therefore, as is known from the past, for example, as specified in the above-mentioned Japanese Patent Application Laid-Open No. 54-105553, no matter how much pre-processing is performed and image formation is performed prior to the start of copying, the light Normal image formation cannot be obtained due to memory effects.

The present invention has been made in view of the above-mentioned drawbacks, and at least separates the main body of the copying machine into upper and lower parts, and when it is closed again, removes the optical memory held by the photoreceptor, and makes one copy after the separation. This provides a method for maintaining the same copy quality as the copy before separation. As a method for removing optical memory, the present invention detects when the top and bottom of the copying machine main body changes from a closed state to an open state and a closed state, and responds to this detection to remove a plurality of photoreceptors. While the photoreceptor is rotated multiple times, some steps of the copying process, such as a charging means and a static elimination means, which are image forming means that repeatedly form images on the photoreceptor, are energized. Removes optical memory generated on the photoreceptor.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a copying machine according to the present invention, and FIG. 2 is an external view showing the main body of the copying machine separated into upper and lower parts. In the figure, reference numeral 1 denotes a drum-shaped photoreceptor that is rotationally driven in the direction of the arrow. On the circumferential surface of the photoreceptor 1, various copying processes for image formation are arranged facing each other. Reference numeral 2 denotes a corona charger for uniformly charging a photoreceptor disposed facing around the rotating circumference of the photoreceptor 1; 3 a corona charger for exposing the uniformly charged surface of the photoreceptor to an image of the document 5 on the document table 4; 6 is an illumination device including an exposure lamp that illuminates the original 5; 7 is a developing device that visualizes the electrostatic latent image formed on the surface of the photoreceptor 1 after image exposure as a toner image; 8 is a paper feeding and A corona charger for electrostatically transferring the toner image onto the copy paper 9 sent through the conveyance system; 10 is a corona charger for eliminating charges remaining on the photoreceptor 1; 11 is a corona charger for eliminating charges remaining on the photoreceptor 1; This is an optical static eliminator using a lamp. In the copying machine shown in FIG. 1, the developing device 7 also serves as a cleaning device to remove toner remaining on the surface of the photoreceptor. Further, 12 is a heat fixing roller for fixing the toner image on the copy paper 9, and 13 is a paper discharge roller for discharging the copy paper 9 after fixing.

In the copying machine shown in FIG. 1, in order to separate the copy paper 9 into upper and lower parts along the conveyance path (the part indicated by the dotted line), the upper part 15 of the copying machine main body is It is configured such that it can be rotated relative to the lower part 16.
Various copying processes provided around the photoreceptor 1 are attached to the upper part 15 of the copying machine main body, and only a corona charger for transfer is attached to the lower part 16 side. In this case, upper and lower rollers of the conveyance system are provided respectively. A spring 17 is attached between the upper part 15 and the lower part 16 of the copying machine main body, and the upper part 15 is always urged upward about the support shaft 14. Furthermore, the fixing of the upper part 15 to the lower part 16 is as follows:
This is done by locking a locking member 18 provided on the upper portion 15 with a locking member (not shown) provided on the lower portion 16. That is, when the locking member 18 is released, the upper portion 15 is opened by the biasing force of the spring 17 as shown in FIG. At this time, the upper part 15
A portion 1a of the photoreceptor attached to the photoreceptor is exposed to external light 19, and optical memory is generated in that portion.

In addition, 20 in the figure is a detection micro switch for detecting opening/closing of the upper part 15 of the copying machine main body, and when the upper part 15 changes from the closed state to the open state and then to the closed state again, the copying machine is separated into the upper and lower parts. This is to detect when something has happened. This micro switch 20
is attached to the lower part 16 main body side. Further, numeral 21 is a power switch, and 22 is a door switch. The door switch 22 changes from a closed state to an open state when the exterior of the copying machine (not shown) is removed, and detects the state in which the exterior of the copying machine is removed. In some cases, it is removed.

In the copying machine configured as described above, a specific example of the configuration for removing the optical memory according to the present invention will next be described in detail.

When the power switch 21 of the copying machine is turned on, power is supplied to the main body of the copying machine. In this case, the detection switch 20 and the door switch 22 detect that the upper part 15 of the copying machine main body and the exterior are closed, and are closed. When the heat fixing roller 12 reaches a temperature that fuses the toner according to the power supply,
The copyable status will be displayed. If the copy switch is pressed in this state, the photoconductor 1
It is effective to perform image formation after the photoreceptor is fatigued to a predetermined state before image formation, as described in JP-A-54-105553, for example. Then, the copy paper conveyance system, the fixing roller 12, etc. start operating. At this time, the slit formed in the synchronous disk 23 provided coaxially with the photoreceptor 1 is detected, and upon receiving this detection slit signal, the copy control circuit sequentially repeatedly forms images on the photoreceptor 1. drive control of various copying processes (image forming means). This copying control circuit is conventionally well known and is used to sequentially control a copying machine. That is, the corona charger 2 uniformly charges the photoreceptor 1, and when the photoreceptor 1 reaches the exposure start position, the document table 4 is also driven and image exposure is performed via the optical system 3. Next, the latent image formed by the image exposure is visualized as a toner image when it reaches the position of the developing device 7, and is transferred onto the copy paper 9 fed through the conveyance system by the action of the transfer corona charger 8. The toner image is transferred. After this transfer, the remaining charge on the photoreceptor 1 is removed by a corona charger 10 for charge removal, and further the charge is optically removed by an optical charge remover 11. Then, when the photoreceptor 1 passes through the corona charger 2, if it reaches the developing device 7 without being corona charged and without being image exposed, the residual toner is removed.
It is ready for the next image formation. In other words, one copy is made by the photoreceptor 1 rotating twice.

On the other hand, the copy paper on which the toner image has been transferred is peeled off from the photoreceptor 1, passes through a thermal fixing roller 12, is fixed, and is discharged from the copying machine via a paper discharge roller 13.

During the above-described copying operation, if the copy paper 9 is jammed in the conveyance path, the upper part 15 of the copying machine main body is opened from the lower part 16 and the jammed paper is removed. In this case, the upper part 15 is separated along the conveyance system, so that its removal is easy. After this removal, the upper part 15 is closed to the lower part 16. When the switch is opened, the detection switch 20 is opened, and when it is closed, it is closed again. Here, when the photoreceptor 1 is opened, a portion 1a of the photoreceptor 1 is irradiated with external light 19, and a light memory effect occurs. In order to eliminate this, when the upper part 15 is closed from the open state to the lower part 16, the detection switch 20 naturally changes from the open state to the closed state, and detects the vertical separation of the copying machine main body. Upon this detection, an optical memory removal operation is started based on a signal from the copy control circuit.

The details will be exemplified below. In response to the change of the detection switch 20 from the open state to the closed state, the copy control circuit first rotates the photoreceptor as in the copying operation. This rotation will be performed multiple times. Due to this rotation, the control circuit receives the synchronization signal from the synchronization disk 23 described above, and sequentially drives some copying processes among the various copying processes as described above. For example, the transfer corona charger 8, the charge eliminating corona charger 10, and the optical charge remover 11 are sequentially driven. The transfer corona charger 8 performs corona discharge of the same polarity as the corona charger 2, and charges the photoreceptor 1 to the same polarity as that used for latent image formation. The photoreceptor 1 is then subjected to corona removal of the charged charges by a charge removal corona charger 10, and further photostatic charge removal by an optical charge remover 11. This operation is repeated four times and all operations are stopped. If the heat fixing roller 12 has reached a temperature that fuses the toner, it enters a standby state in which the copying operation can be started. That is, after the optical memory is removed in accordance with the opening/closing operation of the copying machine, the copying machine is prepared for operation of the copy switch in order to form the next image. Further, during this optical memory removal operation, the corona charger 2, optical system 3, illumination device 6, developing device 7, paper feeding and conveyance system for copy paper 9, etc. are not driven. When the above-described operation is completed, the optical memory effect caused by opening the upper part 15 is removed.

As described above, the optical memory removal according to the present invention detects the vertical opening/closing of the upper and lower parts of the copying machine main body, especially the transition from the open state to the closed state, and based on this detects the rotation of the photoreceptor and the rotation of the photoreceptor. It has means for driving a part of the copying process, which is the image forming means, during rotation, and the optical memory can be effectively removed prior to the copying operation.

In addition to paper jams, the upper part 15 of the copying machine body is opened for maintenance and the like. in this case,
After opening the power switch 21 or the door switch 22, separate the upper part 15 and lower part 16 of the copying machine main body, and after maintenance is completed, remove the upper part 15 and lower part 16.
Close. Then, when the power switch 21 or the door switch 22 is closed again, driving is performed to eliminate the optical memory effect described above.

In the above explanation, the photoreceptor 1 is rotated four times, and each time the corona chargers 8 and 10 and the optical static eliminator 11 are
However, it is not necessarily limited to this number of times, as it changes depending on the conditions of various devices including the photoreceptor 1, the intensity of the external light 19, the irradiation time, the expected safety factor, etc.

Next, an example will be described. After the organic semiconductor photoreceptor 1 is irradiated with external light 19 at 3000 lx for 5 minutes, it is rotated at a circumferential speed of 150 mm/sec. When this photoreceptor was charged with a corona charger 2 with a discharge voltage of 7.2k and a current of 1.2mA, its surface potential decreased to 40-60% compared to the charging value of 500V before irradiation due to the optical memory effect. . Subsequently, in order to remove the optical memory according to the present invention, after passing through a static elimination and static elimination lamp process, the above-mentioned charging was performed, and the surface potential of the photoreceptor was recovered to about 85%. After repeating the process of removing the optical memory four times and performing the above-mentioned charging, it became approximately 95%, and even when copies were made at this point, there was almost no difference in quality from the copies made before irradiation.

As explained above, according to the method for removing optical memory of the present invention, when the copying machine main body is closed after being opened, this is detected, and in response to this, the photoconductor is rotated and the photoconductor is rotated each time. While the body rotates, charging and discharging are repeated multiple times to remove optical memory. The optical memory can then be sufficiently removed to prepare the copier for the next copy.

Therefore, even if image formation is started after the preparation state, since the optical memory has been sufficiently removed, it is possible to form an image with the same image quality as the image before opening the copying machine main body.

Furthermore, the object of the present invention can be achieved by driving part of the charging and neutralizing means for forming an image without the need to separately arrange special means for removing optical memory around the photoreceptor. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a copying machine according to the present invention, and FIG. 2 is an external view showing a state in which the main body of the copying machine is separated into upper and lower parts. 1: Photoreceptor, 2: Corona charger, 8: Corona charger for transfer, 9: Copying paper, 10: Corona charger for static elimination, 11: Optical static eliminator, 15, 16: Upper and lower parts of the copying machine main body, 17 : Spring, 19: External light, 20: Detection switch, 21: Power switch,
22: Door switch.

Claims (1)

[Scope of Claims] 1. A photoreceptor, an image forming means disposed around the photoreceptor including means for rotating the photoreceptor and for repeatedly forming images on the photoreceptor, the photoreceptor and the image forming means In an electrophotographic copying machine configured to be separable substantially along a conveying path of copy paper, in connection with the separation operation of the electrophotographic copying machine main body,
a step of detecting a change from a closed state to an open state and a closed state, and in response to the above detection by separating the main body of the electrophotographic copying machine, each time an optical memory generated by irradiation of external light to the photoreceptor is stored. a step of rotating the photoreceptor a plurality of times in order to remove the charge; and a step of uniformly charging the photoreceptor while the photoreceptor rotates a plurality of times, and charging and neutralizing the image forming means in order to remove the charged charge. a step of energizing the means; and a step of stopping the charging and discharging means of the photoreceptor and the image forming means to prepare for the next image forming state after the rotation of the photoreceptor has stopped a plurality of times; A method for removing optical memory from an electrophotographic copying machine, characterized by removing optical memory from a photoreceptor.