JPH0336576A - Electrostatic copying device - Google Patents

Abstract

PURPOSE:To prevent the degradation of separability and also to prevent the degradation of picture quality and a paper jam beforehand by controlling a pretransfer exposure lamp when such a copying condition that a space is forcibly left in a transfer sheet is set and moreover the transfer sheet requires a prescribed condition. CONSTITUTION:The electrostatic copying device is provided with an operation part 31, which sets various copying mode, the number of copying sheets, a density, etc., a sheet size detecting part 32, which detects the size of a transfer sheet, a transfer sheet weight detecting part 33, and a control part 34 composed of a microcomputer, etc. When such a copying mode that a space is forcibly formed in a part of a transfer sheet is selected, lighting of the pretransfer exposure lamp 7 is controlled, while taking the weight and the size of the transfer sheet into account. For pretransfer exposure lamp 7, its lighting is controlled by the control part 34. Thus, the degradation of separability can be effectively prevented; simultaneously, the degradation of picture quality can also be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention improves transfer separation performance in an electrostatic copying device that can set special copying modes such as masking, trimming, frame erasing, or reduction shift copying. The present invention relates to an electrostatographic copying apparatus.

[Conventional technology]

2. Description of the Related Art Conventionally, there have been copying apparatuses that have a function of copying only a portion of a document, for example. As shown in FIG. 4, this method specifies the area 2a of the original 2 placed on the platen glass 1 by, for example, specifying coordinates, and copies only the area 2a within the specified area (erasing outside the specified area). (See, for example, Japanese Patent Laid-Open No. 60-213168).

[Problem to be solved by the invention]

However, this outside designated area erasing function uses a charged erasing lamp to expose and erase charges on the surface of the photoreceptor, excluding the area corresponding to the designated area 2a of the original 2 described above, to prevent toner from adhering. Therefore, when transferring the toner image to the transfer paper after development,
The adhesion between the transfer paper and the toner-free portion of the photoreceptor becomes stronger. As a result, separation will not be completed completely in the subsequent separation step, and the toner image will change and the image quality will deteriorate, or in the worst case, the transfer paper will wrap around the photoreceptor and a paper jam will occur.

Such an abnormal situation may also occur during designated area erasure (masking), which reversely erases the designated area 2a of the original document 2, and may also occur when erasing the frame portion, shift copying, binding margin copying, and reduction shift copying. It can also occur in some cases. In other words, when the copying conditions are such that a relatively large area remains as a blank on the transfer paper, the above problem is likely to occur especially when the leading edge remains.

The above-mentioned tendency is particularly noticeable when the transfer paper is fed with a stiff horizontal grain (A4, B5) than when it is fed with a stiff horizontal grain (A3, B4', A4R, B5R). This becomes noticeable, and also becomes noticeable when the basis weight (thickness) of the transfer paper is small.

The present invention has been made in view of these points, and its purpose is to reduce the basis weight and paper size of the transfer paper in the case of copying conditions where a blank area remains in a part of the transfer paper as described above. It is an object of the present invention to provide a copying apparatus in which proper separation is performed.

[Means to solve the problem]

To this end, the electrostatic copying apparatus of the present invention includes a first means for detecting that a copying condition that forcibly leaves a blank area on the transfer paper is set, and a first means for detecting the amount of displacement and/or size of the transfer paper. The image forming apparatus includes a second means, and a third means for controlling a pre-transfer exposure lamp based on the detection results of the first means and the second means.

〔Example〕

Examples of the present invention will be described below. FIG. 3 is a diagram schematically showing the copying apparatus. In the electrostatic recording section A, a charged electrode 4,
Charge erasing lamp 5, developing device 6, pre-transfer exposure lamp 7,
A transfer pole 8, a separation pole 9, and a cleaning device 10 are arranged in this order.

Further, upstream of the transfer pole 8, a registration roller 12 is provided that temporarily stops the transfer paper fed from the paper feed section 11 to adjust the timing, and further downstream of the separation pole 9, a conveyor belt 13 and a heat fixing roller are provided. Devices 14 are provided one after the other.

On the other hand, in the document reading section B, a rod-shaped exposure light source 15 that travels in the direction indicated by the arrow on the lower surface of the platen glass 1 on which the document 2 is set and exposes the document 2, and a photoreceptor is provided with the reflected image light obtained by exposure. Mirrors 16 to 19, a lens 20, and the like are provided for transmitting information to the 3.

In this copying apparatus, an original 2 on a platen glass 1 is exposed by scanning an exposure light source 15 in the direction of the arrow. When the image light obtained by this exposure is incident on the photoreceptor 3, the charge on the light irradiated portion of the photoreceptor, which has been previously charged at a high voltage by the charging electrode 4, decreases in accordance with the degree of brightness, and the original is placed there. An electrostatic latent image corresponding to the image is formed. and,
As the photoreceptor 3 rotates, this electrostatic latent image portion is transferred to the developing device 6.
When the image reaches the sleeve 6a, it is developed there with toner, forming a toner image corresponding to the image of the document. Then, this toner image is transferred from the registration roller 12 to a transfer sheet fed at a timing when the leading edge of the image coincides with each other at a transfer pole 8, and further reaches a separation pole 9 where it is separated from the surface of the photoreceptor 1. and,
The transfer paper carrying the toner image is then transferred to the conveyor belt 13.
The image is then sent to the thermal fixing device E14, where it is thermally fixed, and then ejected. The photoconductor 3 on which toner remains is cleaned by the blade 10a when it reaches the cleaning device 10, and is prepared for the next cycle.

When copying only the specified area 2a of the document 2 described above, information corresponding to the specified area is transmitted to the charge erasing lamp 5, and the charge erasing lamp 5 is connected to a plurality of L
By lighting a predetermined one of the EDs at a predetermined timing, the designated area 2 of the document 2 on the photoreceptor 3 is
Charges outside the region corresponding to a are erased. As a result, the adhesion of the transfer paper to the erased portion increases, and the separation performance deteriorates as described above.

Therefore, in this embodiment, the pre-transfer exposure lamp 7 is disposed between the developing device 6 and the transfer pole 8 as described above. Regarding this pre-transfer exposure lamp 7, Japanese Patent Application Laid-Open No. 58-6267
5, 5B-62676, Japanese Patent Application No. 16117-1983, etc.

In this embodiment, when a copy mode is selected in which a blank area is forcibly formed in a part of the transfer paper as described above, the transfer paper is The lighting of the exposure lamp 7 is controlled.

FIG. 1 is a diagram showing this control system. 31 is an operation unit for setting various copy modes, number of copies, density, etc., 32
33 is a paper size detection unit that detects the paper size of the transfer paper;
Reference numeral 34 indicates a transfer paper basis weight detection unit, and 34 a control unit comprising a microcomputer or the like, and the lighting of the pre-transfer exposure lamp 7 is controlled by this control unit 34.

As the paper size detection section 32 described above, a transfer paper size detection section provided in a transfer paper cassette can be used. See you again! The detection section 33 may be one in which a light transmission sensor is disposed in the path of the transfer paper from the paper feed section 11 to the registration roller 12, and the detection is performed based on the amount of light transmitted by the light transmission sensor.

FIG. 2 is a diagram showing a flowchart of a control program when lighting of the pre-transfer exposure lamp 7 is controlled. Here, in the above-described operation unit 31, one of the modes of erase outside the specified area, erase within the specified area, frame erase, and reduction shift is selected, and the command is taken into the control unit 34,
At this time, the basis weight of the transfer paper is small (thin, e.g. 55g)
/m” or less) is not detected and the paper size is A4,
If B5 is also not detected, the pre-transfer exposure lamp 7 is turned on weakly. Further, in addition to the selection of the above mode, if it is detected that the basis weight of the transfer paper is small, or if it is detected that the paper size is A4 or B5, the pre-transfer exposure lamp 7 is strongly lit.

As a result, when a copy mode is set in which a blank area is forcibly formed in a part of the transfer paper, the surface of the photoreceptor 3 is irradiated by the pre-transfer exposure lamp 7, and its potential is lowered. Moreover, at this time, if the basis weight of the transfer paper is small or the size of the transfer paper is A4 or B5, the pre-transfer exposure lamp 7 will be lit strongly, so the surface of the photoreceptor 3 will be more strongly irradiated, and its The potential drop becomes deeper.

In this way, when the separation efficiency is reduced, the potential of the photoreceptor 3 is reduced depending on the degree of the condition.
Deterioration of separation performance can be effectively prevented, and at the same time, deterioration of image quality can also be prevented.

In the above, only the erase outside specified area, erase within specified area, frame erase, and reduction shift are shown as copy modes that forcibly create a blank area in a part of the transfer paper, but there are other copy modes such as shift copy and binding. There are other types such as substitute copies.

In addition, in the above embodiment, the pre-transfer exposure lamp is turned on in a copy mode that forcibly forms a blank area in a part of the transfer paper, and in addition to that mode, the lamp is turned on when the transfer paper is likely to be separated poorly. Although the lighting is switched to a more powerful state, the present invention is not limited to this.

For example, in addition to setting the copy mode, the pre-transfer exposure lamp may be controlled to be turned on only when the transfer paper conditions are satisfied.

Furthermore, the lighting state of the pre-transfer exposure lamp can be switched to three or more stages depending on the basis weight of the transfer paper or the specific paper size.

Furthermore, the light is turned on weakly when only the above copy mode setting is set, the light is turned on in the middle when one of the paper size conditions is satisfied, and the light is turned on strongly when both conditions are satisfied. You can also do that.

Furthermore, other controls for the pre-transfer exposure lamp 7 include replacing and adding filters.

〔Effect of the invention〕

As explained above, according to the present invention, the copying conditions are set to forcefully leave a blank area on the transfer paper, and the pre-transfer exposure lamp is controlled when the transfer paper is under the predetermined conditions, so that separation performance can be improved. This has the advantage of being able to prevent deterioration and prevent image quality deterioration and paper jams.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a control unit according to an embodiment of the present invention, FIG. 2 is a flowchart of its control program, FIG. 3 is a schematic configuration diagram of a copying machine, and FIG. 4 is an explanatory diagram of erasing outside a specified area. be. 5... Charge erase lamp, 7... Pre-transfer exposure lamp.

Claims (2)

[Claims] (1) a first means for detecting that a copying condition forcibly leaving a blank area on the transfer paper is set; a second means for detecting the amount of displacement and/or size of the transfer paper; An electrostatic copying apparatus comprising: means and third means for controlling a pre-transfer exposure lamp based on the detection result of the second means. (2) The first means includes a designated area erase mode, a designated area erase mode, a frame erase mode, a shift copy mode,
2. The electrostatic copying apparatus according to claim 1, wherein the electrostatic copying apparatus detects the setting of a binding margin production mode or a reduction shift mode.