JPS62981A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent residual toner which can not be cleaned up by a magnetic brush from being formed by discriminating whether the size or feed state of recording paper fed to a discharge transfer device is proper or not, and turning off the transfer device when it is discriminated that the side or feed state is not proper. CONSTITUTION:Paper feeding operation begins to be performed by a register roller 10 so the front end of recording paper meets the front end of a toner image, and then when the front end of the recording paper is detected by a sensor 11 within a specific time, it is discriminated that the recording paper feed state is proper, thereby performing transfer operation. When the detection time of the sensor 11 is different from specific time, it is discriminated that the paper feed state is improper and the transfer device 4 is turned off. Therefore, the toner time which is not covered with recording paper at a discharge transfer position is not charged electrostatically and residual toner which still sticks on a photosensitive body 7 even after passing through the transfer device is easily removed by the magnetic brush of a cleaning device 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic apparatus such as an electrophotographic copying machine. In particular, the present invention relates to an improvement in an electrophotographic apparatus that includes a discharge transfer device and a magnetic brush cleaning device provided downstream of the discharge transfer device, and is operated by process control.

2. Description of the Related Art In an electrophotographic apparatus such as an electrophotographic copying machine (hereinafter referred to as a copying machine), residual toner adhering to a drum-shaped or belt-shaped photoreceptor after being transferred to recording paper is removed by a magnetic brush. However, if there is a part that was not transferred during transfer (hereinafter referred to as an untransferred part),
Since the residual toner in the untransferred area is not removed but is instead developed, there is a problem that a good quality copy image cannot be obtained in the next copying operation.

Conventionally, in order to solve the above-mentioned problems, devices have been developed in which the photoconductor is photostatically neutralized or statically neutralized by A (3 corona discharge, etc.) before cleaning, but the static electricity in the untransferred area is not sufficiently eliminated. , the cleaning effect cannot be achieved.Also, the magnetic brush is not connected to AC.
Although a method has been developed in which the cleaning effect is increased by applying a bias voltage, it is still not possible to achieve a sufficient effect on the untransferred area, as described above.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems, and to provide an electrophotographic apparatus that prevents the generation of residual toner that cannot be cleaned with a magnetic brush and that can be cleaned satisfactorily. nihiru.

Structure of the Invention The present inventor has obtained the following knowledge as a result of research to achieve the above object. The residual toner in the untransferred area is the toner in the part of the toner image formed on the photoreceptor that is not covered by the recording paper during transfer, and is charged by being directly discharged by a discharge transfer device, such as corona discharge, during transfer. be done. Therefore, the residual toner in the untransferred area is often not removed by the magnetic brush of the magnetic brush cleaning device, but instead is developed. Further, in the untransferred area, recording paper of an appropriate size is not fed in an appropriate state to the discharge transfer position of the discharge transfer device, and the toner image formed on the photoreceptor is covered with the recording paper at the discharge transfer position. It has become clear that this occurs when there is no From the above, if recording paper of an appropriate size is not fed in an appropriate state at the time of transfer, the discharge transfer device is set to a non-operating state. Therefore, the toner image that is not covered by the recording paper at the discharge transfer position It has been found that charging of the residual toner in the untransferred area can be prevented.

The present invention has been completed based on the above-mentioned knowledge, and has a configuration including a discharge transfer device and a magnetic brush cleaning device provided downstream of the discharge transfer device, and an electronic brush cleaning device operated by process control. In a photographic device, it is determined whether the size of recording paper fed to the discharge transfer device or the paper feeding state is appropriate, and if it is determined that the paper is inappropriate, the transfer device is set to a non-operating state. This is an electrophotographic device characterized by:

The present invention is configured as described above, and if recording paper of an appropriate size is fed in an appropriate state at the time of transfer, the image is properly transferred to the recording paper without any untransferred portions. The residual toner adhering to the photoreceptor after transfer is only in the transfer portion and is not charged, and is appropriately removed by a magnetic brush cleaning device. On the other hand, if recording paper of the appropriate size is not fed in an appropriate state during transfer, the discharge transfer device is set to an inactive state, so no unnecessary transfer is performed on the recording paper, and there is a possibility that the photoconductor may Since the formed toner image is not charged, residual toner adhering to the photoconductor □ after passing through the discharge transfer device is appropriately removed by the magnetic brush cleaning device.

The following example shows a case where it is determined that the discharge transfer, the size of the recording paper fed to the apparatus, or the paper feeding state is inappropriate. If the size of the recording paper is smaller in length and/or width than the toner image formed on the photoreceptor, even if the size of the recording paper is the same or larger than the size of the toner image, at the discharge transfer position of the discharge transfer device. If the leading or trailing edge of the recording paper is not fed so as to match each of the toner images, the recording paper is not stored in the paper feed cassette or is jammed in the paper feed path and is not fed to the discharge transfer position. Cases etc.

Note that the size of the recording paper fed to the discharge transfer device or the suitability of the paper feeding state can be determined by installing a sensor built into the paper feed path as part of the process control device that operates the electrophotographic device, for example. time for recording paper fed from the paper cassette to reach the sensor, time for it to pass through the sensor, or if multiple sensors are provided, time for it to reach each sensor or each sensor. Detects the length, width, etc. of the recording paper being fed, determines when the paper feed reaches the discharge transfer position, determines the speed, paper feeding posture, etc., and determines the determination result of the recording paper. When compared with the size of the toner image formed on the photoreceptor, the timing or speed at which the toner image reaches the discharge transfer position, etc., it is determined by K.

Example The present invention will be explained in detail by way of examples.

First Embodiment A first embodiment will be explained based on FIG. FIG. 1 is an explanatory diagram schematically illustrating an electrophotographic copying machine according to a first embodiment. The electrophotographic copying machine shown in the figure has a charger 1. Exposure device 2.
Magnetic brush developing device 3 (hereinafter referred to as developing device) I transfer device 49 having a corona discharge electrode separator 5. Fuser6. A drum-shaped photoreceptor 7, a magnetic brush cleaning device 8 (hereinafter referred to as the cleaning device), and a paper feed cassette 9 for storing recording paper. It is equipped with a sensor 11 for detecting registration rollers and lO1 recording, and is configured to be operated by a process control device (not shown).

Note that if the sensor 11 detects recording paper of an appropriate size within a predetermined time after the registration roller 10 is activated, the transfer device 4 will move the leading edge of the recording paper to the transfer device 4.
For example, from a microcomputer or the like operated in conjunction with the process control device, the control signal is set to the activated state when the sensor 11 reaches C. It is controlled by a discriminating means.

The electrophotographic copying machine shown in the figure is constructed as described above, and copying operations are performed as follows. When a copy start switch (not shown) is turned on, the photoreceptor 7 starts rotating. During one rotation of the photoreceptor 7, the photoreceptor 7 is sequentially subjected to charging, exposure, development, transfer and separation, and cleaning.
Further, the recording paper separated after the transfer is subjected to a fixing process to form one copy. That is, the photoreceptor 7 is charged by the charger 1, and the exposure device 2 exposes the original image to form a latent image. The latent image formed on the photoreceptor 7 is developed by the developing device 3 and formed into a toner image. The toner image is transferred by the transfer device 4 onto the recording paper fed by the registration rollers 10 such that the timing and speed at which the leading edge of the toner image reaches the transfer device 4 match.

At this time, 60 to 90% of the toner forming the toner image is transferred to the recording paper, but 10 to 40% remains attached to the photoreceptor 7 as residual toner. After the recording paper is separated from the photoreceptor 7, the residual toner is attracted to the magnetic brush of the cleaning device 8 and removed from the photoreceptor 7. On the other hand, the recording paper separated from the photoreceptor 7 by the separator 5 after the transfer is fed to the fixing device 6, where the transferred original image is fixed.

In the above operation, the transfer device 4 is operated as follows.

The recording paper stored in the paper feed cassette 9 is once fed from the paper feed cassette 9 to the registration rollers 10 by process control. Thereafter, the registration roller 10 is started to operate under one process control so that the leading edge of the recording paper coincides with the leading edge of the toner image in the transfer device 4. When the leading edge □ of the recording paper is detected by the sensor 11 within a predetermined time after the registration roller 10 starts operating, it is determined that the paper feeding state of the recording paper is appropriate, and the transfer device 4 enters the operating state. settings, and transfer takes place as usual.

However, when the recording paper is detected by the sensor 11 earlier or later than the predetermined time, it is determined that the paper feeding state of the recording paper is inappropriate, and the transfer device 4 is set to a non-operating state. , no transfer is performed on the transfer paper. Of course, if the recording paper is not fed in the paper feed cassette 9, or if the recording paper is jammed, the sensor 1. 1 is not detected, the transfer device 4 is set to a non-operating state.

As described above, in this embodiment, when feeding recording paper of an appropriate size, if the leading edge of the recording paper does not reach the transfer device 4 at an appropriate time, the image is formed on the photoreceptor 7 at the transfer position. Although the leading edge or trailing edge of the toner image is not covered by the recording paper, since the transfer device 4 is set to an inactive state, the leading edge or trailing edge of the toner image is not subjected to discharge and the toner image is formed. The toner is easily removed by being attracted by the magnetic brush of the cleaning device 8. In this embodiment, it is preferable that the sensor 11 is configured to also detect the trailing edge of the recording paper. It is also possible to determine whether the length of the recording paper is longer than a predetermined length.

That is, even if the leading edge of the recording paper is detected by the sensor 11 within a predetermined time, if the elapsed time until the trailing edge is detected is short, the length of the recording paper is shorter than the predetermined length. If the elapsed time is long, it can be determined that the elapsed time is longer than the predetermined length.

Therefore, when it is determined that the length of the recording paper is shorter than the predetermined length, the trailing edge of the recording paper passes through the transfer device 4 even if the recording paper is properly fed. By configuring the transfer device 4 so that it can be set to a non-operating state until then, it is possible to prevent discharge for transfer from being performed on a toner image that is not covered by the recording paper. Further, when a plurality of the sensors are arranged in a direction perpendicular to the paper feeding direction of the recording paper, and a sensor corresponding to the width of the toner image is set to an active state, and the sensors set to the above-mentioned active state do not operate at the same time, may be configured such that the transfer device does not operate. In this case, check whether the width of the recording paper is greater than the specified width, whether the recording paper is fed properly through the paper feed path without being tilted, or whether the recording paper is bent. Since it is possible to determine whether or not the paper is being fed properly, it can be used in cases where recording paper that is narrower than the specified width is being fed, or when paper is being fed in an inappropriate paper feeding state. , the transfer device 4 can be set to an inactive state. Furthermore, multiple sensors are arranged in the direction of the recording paper feed path.
It may be configured to detect the time at which the leading edge of the recording paper reaches each sensor, and to determine whether the feeding speed of the recording paper is appropriate based on the difference between the respective times.

When an AC discharge electrode such as an AC corona discharge electrode is used, the separator 5 has the effect of neutralizing the photoreceptor and residual toner, so it is operated by process control regardless of the operating state of the transfer device 4. It is preferable that the

Second Embodiment A second embodiment will be explained based on FIG. 2. Figure 1 shows the second
FIG. 1 is an explanatory diagram schematically explaining an electrophotographic copying machine according to an embodiment. In the figure, the same reference numerals as in FIG. 1 indicate the same functional members. In the electrophotographic copying machine shown in FIG. 2, compared to the one shown in FIG. 1, the magnetic brush unit A serves both as a developing device and a cleaning device, and one
The difference is that copies can be made.

In other words, during the first rotation of the photoreceptor 7, charging pi! The processes of light, photoimage development, separation, fixing of the separated recording paper after transfer, etc. are performed in the same manner as shown in FIG. 2
During the rotation, the charger 12, transfer device 4, separator 5, etc. are set to a non-operating state, and the magnetic brush unit A is operated as a cleaning device to remove residual toner adhering to the photoreceptor 7. In this case, at the time of transfer, the transfer device 4 is set to be activated or deactivated in relation to the fed recording paper in the same way as shown in FIG. The residual toner adhering to the body is not charged by the transfer device 4, but is attracted to the magnetic brush and removed.

Effects of the Invention As explained in the embodiments, the electrophotographic apparatus of the present invention determines whether the size of the recording paper or the paper feeding condition is appropriate during transfer, and if it is determined that the paper feeding condition is inappropriate, the electrophotographic apparatus of the present invention stops the transfer apparatus. By setting the transfer device to the inactive state, the toner image that is not covered by the recording paper at the discharge transfer position of the transfer device is not charged, unlike conventional devices.
Residual toner adhering to the photoreceptor after passing through the transfer device can be removed by a magnetic brush cleaning device.

As described above, the present invention was able to achieve the above object with the above configuration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic explanatory diagram of a first embodiment of the present invention. FIG. 2 is also a schematic explanatory diagram of the second embodiment. 3...Magnetic brush developing device. 4... Transfer device + 7... Drum-shaped photoreceptor. 8... Magnetic brush cleaning device t9... Paper feed cassette, 10... Registration roller 11... Sensor, A... Magnetic brush unit.

Claims (4)

[Claims] (1) In an electrophotographic apparatus that is equipped with a discharge transfer device and a magnetic brush cleaning device provided downstream of the discharge transfer device and is operated by process control, recording paper is fed to the discharge transfer device. 1. An electrophotographic apparatus characterized in that the transfer device is set to a non-operating state when it is determined that the size or feeding state of the paper is inappropriate. (2) The electrophotographic apparatus according to claim 1, wherein the magnetic brush cleaning device also serves as a developing device. (3) The scope of the present invention is characterized in that the size of the recording paper is determined to be inappropriate if the length and/or width of the recording paper is smaller than a predetermined dimension. The electrophotographic apparatus according to item 1 or 2. (4) The suitability of the feeding state of the recording paper is determined if the recording paper is not fed at the specified timing, if the recording paper is not fed, or if the recording paper is not in the specified paper feeding path. 4. The electrophotographic apparatus according to claim 1, wherein the electrophotographic apparatus is determined to be inappropriate if the paper is not fed along the same direction.