JPH0336578A - 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 caused by defective separation beforehand by controlling a pretransfer exposure lamp according to the conditions of copying, transfer sheet, and humidity. CONSTITUTION:The electrostatic copying device is provided with a sheet size detecting part 32 for detecting the size of a transfer sheet, a transfer sheet weight detecting part 33, a humidity detecting part 35, and a control part 36 composed of a microcomputer, etc. When such a copying mode that a space is forcibly formed in one part of a transfer sheet is selected, the lighting of the pretransfer exposure lamp 7 is controlled, while taking the weight, the size, and the humidity of the transfer sheet into account. That is, for the pretransfer exposure lamp 7, its lighting is controlled by the control part 36. Thus, when such a copying condition that a space is left in a part of the transfer sheet is set, proper separation is carried out, while taking the weight, the size, the humidity, etc., of the transfer sheet into account; therefore the occurrence of the degradation of picture quality and a paper jam can 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 document 2 placed on the platen glass l by means such as specifying coordinates, and copies only the area within the specified area 2a (deletes outside the specified area). Nidoriming〉Yo G
(For example, Japanese Patent Application Laid-Open No. 60-213168
(see publication).

[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 is not performed completely in the subsequent separation step, resulting in changes in the toner image and deterioration of image quality, or in the worst case scenario, the transfer paper wraps around the photoreceptor, causing a paper jam.

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 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 more pronounced than when the transfer paper is fed with stiff vertical grain (A3, B4, A4R, B5R).
This is particularly noticeable when the transfer paper is fed with a weak cross-grain (A4, B5), and is also noticeable when the basis weight (thickness) of the transfer paper is small. Furthermore, if the humidity is out of a predetermined range, the problem will become more noticeable.

The present invention has been made in view of these points, and its purpose is to improve the basis weight of the transfer paper, paper size, It is an object of the present invention to provide a copying apparatus that performs proper separation in consideration of humidity and the like.

[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 apparatus includes a second means, a third means for detecting humidity, and a fourth means for controlling the pre-transfer exposure lamp based on the detection results of the first means to the third means.

[Examples] 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 of the arrow on the lower surface of the platen glass l on which the document 2 is set and exposes the document 2 receives reflected image light from the photoreceptor. Mirrors 16 to 19, a lens 20, and the like are provided for transmitting information to the 3.

In this copying apparatus, the original 2 on the platen glass l is exposed by scanning the 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 sent 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 l. and,
The transfer paper carrying the toner image is then transferred to the conveyor belt 13.
The image is sent to the thermal fixing device 14, where it is thermally fixed, and the sheet is ejected. The photoreceptor 3 on which toner remains is cleaned by the blade 10a when it reaches the cleaning device IO, 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 plurality of L's constituting the charge erasing lamp 5 are
By lighting up a predetermined item in the EDO 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, No. 58-62676, Japanese Patent Application No. 63-16117, etc.

In this example, when a copy mode in which a blank area is forcibly formed in a part of the transfer paper is selected as described above, the basis weight and size of the transfer paper and temperature/humidity are also taken into consideration. Accordingly, the lighting of the pre-transfer 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;
34 is a temperature detection section, 35 is a humidity detection section, and 36 is a control section consisting of a microcomputer or the like, and the lighting of the pre-transfer exposure lamp 7 is controlled by this control section 36.

As the paper size detection section 32 described above, a transfer paper size detection section provided in a transfer paper cassette can be used. In addition, the basis weight detection section 33 is configured such that a light transmission sensor is arranged 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. Can be used. Furthermore,
The temperature detection section 34 and the humidity detection section 35 are installed in the path or near the cassette so that they can detect the temperature and humidity of the transfer paper.

FIG. 2 is a diagram showing a flowchart of a control program when lighting of the pre-transfer exposure lamp 7 is controlled. Here, when one of the modes of erase outside the specified area, erase within the specified area, frame erase, and reduction shift is selected in the operation unit 31 described above and the command is taken into the control unit 36, the transfer paper is Assuming that a copying condition in which a separation failure from the photoreceptor 3 is likely to occur is established, the pre-transfer exposure lamp 7 is turned on one stage (the weakest lighting).

At this time, in addition to the above copying conditions being met, it is detected that the basis weight of the transfer paper is small (thin, for example, 55 g/m2 or less), or that the paper size is A, 4, or B5. In this case, the conditions of the transfer paper itself tend to cause poor separation, so the pre-transfer exposure lamp 7
lights up in two stages (lit more strongly than the first stage).

Furthermore, at this time, in addition to the above-mentioned copying conditions being met and the above-mentioned transfer paper conditions being met, the humidity is over 80% and the temperature is 33%.
If the temperature exceeds ℃, or if the humidity is 20% or less and the humidity is 10℃ or less, the transfer paper becomes stiff and the transfer paper is easily charged with static electricity, so the pre-transfer exposure lamp 7 is set in three stages. Lights up (lights more powerful than 2-stage lighting).

In this way, the copying conditions are met, the transfer paper conditions are met, and the temperature/
As the atmospheric conditions such as humidity are established, the lighting state of the pre-transfer exposure lamp 7 is controlled to be gradually increased, so that the surface charge of the photoreceptor 30 decreases more deeply in response to the establishment of the conditions. Therefore, the lighting of the pre-transfer exposure lamp, which may have an adverse effect on the toner image on the photoreceptor, can be kept to the minimum necessary level so that poor separation does not occur.

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.

Further, although the atmospheric conditions are detected using the preconditions of temperature and humidity in the above example, the atmospheric conditions can also be determined based only on the humidity conditions.

Furthermore, in the embodiment described above, the lighting state of the pre-transfer exposure lamp is controlled to be sequentially and strongly changed each time the condition is satisfied, but the present invention is not limited to this.

For example, the pre-transfer exposure lamp may be controlled to be turned on only when the copying conditions, transfer paper conditions, and atmosphere conditions are satisfied.

In addition, depending on the basis weight of the transfer paper, the specific paper size, or the level of humidity, the lighting state of the pre-transfer exposure lamp can be set to 4.
You can also switch to more than one level.

Furthermore, it is also possible to turn on the lamp weakly only when the above-mentioned copying conditions are satisfied, and to turn on the lamp more strongly when the transfer paper conditions or atmosphere conditions are satisfied.

〔Effect of the invention〕

As explained above, according to the present invention, the pre-transfer exposure lamp is controlled according to copying conditions, transfer paper conditions, and humidity conditions, so deterioration of separation performance can be prevented, and image quality deterioration due to poor separation can be prevented. This has the advantage of being able to prevent 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 copying conditions have been set to forcefully leave a blank area on the transfer paper, a second means for detecting the amount and/or size of the transfer paper, and a second means for detecting humidity. and a fourth means for controlling a pre-transfer exposure lamp based on the detection results of the first to third 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.