JPH04204769A - Electrophotographic printer - Google Patents

Abstract

PURPOSE:To prevent a failure in peeling by detecting the surface potential of a photosensitive drum before a transfer and controlling a surface potential adjusting means such as pretransfer erasing light, or the peeling means of an AC corona dischager, etc., or both of the surface potential adjusting means and the peeling means. CONSTITUTION:The surface potential of the photosensitive drum before the transfer is detected and the surface potential of the photosensitive drum is controlled by the surface potential adjusting means such as the pretransfer erasing light, so as to properly carry out the peeling of a sheet after the transfer, and a sheet peeling means such as the AC corona discharger 12, and an electrifier 2 is controlled. In other words, the surface potential of the photosensitive drum before the transfer is properly adjusted, and the current, voltage, etc., of the AC corona discharger 12, the electrifier 2, etc., for peeling the sheet are properly controlled. Thus, pollution caused by the toner of the photosensitive drum surface potential adjusting means such as the erasing light is periodicaly cleaned and a secular change in the characteristics of the photosensitive drum 1 and its environmental dependency change are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic printing apparatus, and more particularly, to an electrophotographic printing apparatus that can appropriately peel off paper onto which a toner image from a photoreceptor has been transferred.

[Conventional technology]

FIG. 4 is a diagram showing an outline of a conventional electrophotographic printing apparatus.

In FIG. 4, exposure light 3 is irradiated onto a photoconductive drum 1, which is a photoconductor that has been charged in a dark place by an electric device 2, to form an electrostatic latent image of an image pattern. The electrostatic latent image is converted into a toner image by the developer 20 in the developing section 21 by the developing device 4 and is visualized.

The toner image on the photosensitive tram 1 overlaps the paper 19 conveyed by the conveyance roller 8, and the transfer device
From the back side of the paper t 9 [:], a corona discharge with a polarity opposite to that of the toner image is transferred to the paper t 9 [:].

During the transfer, the paper 19 is attracted to the photosensitive drum 1 due to static electricity, so the AC corona discharger 18 neutralizes the static electricity, peels off the paper 19, and transfers it to the fixing device 29 via the paper conveyor 14. send it and fix it.

In addition, since the discharge of the z corona discharger 18 tends to become unstable due to changes in the environment or dirt, for example, the paper wrapped around the photosensitive drum 1 may be peeled off using the paper peeling claw 22, or the z corona discharger 18 may be The erase 5 weakens the adhesion between the photosensitive drum 1 and the paper 19.

FIG. 5 is a diagram showing an electric field pattern on the photosensitive drum 1 during regular development, and FIG. 6 is a diagram showing an electric field pattern on the photosensitive drum 1 during reversal development. (2) is the potential lowered due to exposure, and VH is the potential of the portion not exposed to light.

In the case of reversal development, V corresponds to 4 white background areas.

Since the paper 19 is strongly attracted to the photosensitive tram ↓ since the paper 19 occupies most of the area, the entire surface of the drum 1 is irradiated with erase light before transfer. The belt was omitted, and the charged toner image on the photoreceptor was directly transferred to paper and peeled off by a peeling corotron.

[Problem to be solved by the invention]

In the conventional electrophotographic printing apparatus described above, although the paper peeling claw 22 can prevent paper that could not be peeled off by the AC corona device from wrapping around the photosensitive drum, it cannot completely prevent the occurrence of paper jams. The problem was that there was no.

In addition, the pre-transfer erase light 5 may be contaminated due to toner scattering and the light intensity may be reduced, and the characteristics of the photosensitive drum 1 may change due to changes over time or environmental dependence, making the paper peeling characteristics unstable. There is also the problem that maintenance costs increase because it is necessary to periodically clean or replace.

SUMMARY OF THE INVENTION An object of the present invention is to provide an e-1-v page printing apparatus that eliminates the drawbacks of the conventional apparatus and does not cause peeling defects.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention detects the surface potential of a photosensitive drum before transfer and uses a surface potential adjusting means such as a pre-transfer erase light, or a peeling means such as an AC corona discharger, or a peeling means and the above-mentioned surface potential adjusting means. Try to control both means.

For this reason, the surface potential *a means is controlled by an error signal obtained by comparing the output signal of the photosensitive drum surface potential detection means before transfer with a reference surface potential signal.

Furthermore, a plurality of reference surface potential signals corresponding to the paper type are stored so that one of them can be designated.

Furthermore, the characteristics of the input signal of the surface potential adjusting means with respect to the output signal of the surface potential detecting means are stored for each type of paper so that one of them can be specified, and the characteristics of the input signal of the surface potential adjusting means with respect to the output signal of the surface potential detecting means are stored. The input signal of the surface potential adjusting means is read by accessing the second storage means.

[Effect]

The electrophotographic printing apparatus of the present invention configured as described above detects the surface potential of the photosensitive drum before transfer and uses surface potential adjustment means such as pre-transfer erase light to properly peel off the paper after transfer. It controls the surface potential of the photosensitive drum before transfer, and also controls paper peeling means such as an AC corona discharger and a charger.

Further, each of the above controls can be switched for each type of paper.

〔Example〕

FIG. 1 is a diagram illustrating the configuration of an electrophotographic printing apparatus according to the present invention.

In FIG. 1, a surface potential sensor 7 is provided after the pre-transfer erase light 5 which is a means for adjusting the pre-transfer surface potential of the photosensitive drum, and a control circuit 17 controls the power source 6 of the pre-transfer erase light 5 according to its output. The light intensity of the pre-transfer erase light 5 is controlled, and the AC power supply 13 of the AC corona discharger 12, which is a paper peeling means after transfer, is controlled to remove the photosensitive drum 1.
control the surface potential of

Furthermore, since the intensity of the pre-transfer erase light 5 has a particularly large effect on the paper peeling, only the power supply 6 for the pre-transfer erase light 5 can be controlled by the output of the surface potential sensor 7. Similarly, only the AC power source ]-3 of the AC corona discharger 12 may be controlled.

FIG. 2 shows data showing the relationship between the potential on the surface of the photosensitive drum 1 immediately before transfer and the peeling failure of the paper 19.

However, this data uses a phthalocyanine-based organic photoconductor for the photoconductor on the surface of the photoconductor drum 1, a reversal dry magnetic brush development method for the development method, and a white fluorescent lamp with a green filter for the pre-transfer erase light 5. , the paper 19 is a plain paper having an area weight of s og/m.

Therefore, if the surface potential of the photosensitive drum 1 exceeds 1500 V, paper peeling failure occurs, so the control circuit 17 controls the AC corona discharger 12 in accordance with the output signal of the surface potential sensor 7.
The AC power source 13 of the pre-transfer erase light 5 is compared with a reference potential value of less than -500V, and the obtained error signal is used to adjust the power source 6 of the pre-transfer erase light 5.
The surface potential of the photosensitive drum 1 is set to -5o by controlling the
It is maintained at a predetermined value less than ov.

The above reference potential varies depending on the paper quality, thickness, etc.
The reference potentials for each type of paper are stored, and one of them can be specified. A memory, a switching circuit, etc. for this purpose may be provided within the control circuit 17, for example.

Further, since there is a relationship as shown in FIG. 3 between the potential immediately before transfer on the surface of the photosensitive drum 1 and the amount of pre-transfer erase light 5, the control circuit 17 stores this relationship and controls the photosensitive drum 1.
It is also possible to calculate and control the amount of the pre-transfer erase light 5 based on the measured value of the surface potential immediately before transfer.

Since the characteristics shown in FIG. 3 above differ depending on the paper quality, thickness, etc., the above-mentioned characteristics for each type of paper are stored so that one of them can be specified.

The memory, switching circuit, etc. for this purpose are, for example, the control circuit 1.
It should be set within 7.

FIG. 7 is a diagram showing a case in which the present invention is applied to an electrophotographic printing apparatus of a type in which paper 19 is conveyed by a transfer belt 26. The transfer belt 26 is charged with a polarity opposite to that of the toner by the band ti27, and attracts and conveys the paper 19.

The control circuit 17 controls the DC power source 28 of the charger 27 in accordance with the surface potential of the photosensitive drum 1 in accordance with the output signal of the surface potential sensor 7, and further similarly controls the power source 6 of the pre-transfer erase light 5.

〔Effect of the invention〕

According to the present invention, the surface potential of the photosensitive drum before transfer is properly adjusted, and the current, voltage, etc. of the A and C Freon dischargers and chargers for paper peeling are appropriately controlled, so paper jams, etc. It is possible to prevent paper peeling means after the transfer.

In addition, due to the above effects, it is possible to periodically clean the toner contamination of the photosensitive drum surface potential adjustment means such as pre-transfer erase light, and to prevent the characteristics of the photosensitive drum 1 from changing over time or depending on the environment. Since the frequency of replacement can be reduced, maintenance costs can be reduced and reliability can be improved.

[Brief explanation of the drawing]

1 and 7 are diagrams each explaining the configuration of an electrophotographic printing apparatus according to the present invention. FIG. 2 is a diagram showing the relationship between the surface potential of the photosensitive drum and paper peeling. 5 FIG. 3 is a diagram showing the relationship between the surface potential of the photosensitive drum and erase before transfer FIG. 4 is a diagram illustrating the structure of a conventional electrophotographic printing apparatus, and FIGS. 5 and 6 are diagrams each showing an example of the surface potential of a photosensitive drum. 1 is a photoreceptor drum, 2 and 27 are each charger, 3 is an exposure device, 4
5 is a developing device, 5 is a pre-transfer erase light, 6, 11, and 28 are power sources, 7 is a surface potential sensor, 8 is a conveyance roller, 9 is a guide, and 10 is a transfer device. 12 is an AC corona discharger 513, 18 is each AC power supply, 1
4 is a paper conveyance device, and 15 is a heat roller. 16 is a back-up roller, 17 is a control circuit, 19 is paper, 20 is a developer, 2] 8 is a developing section, 22 is a paper peeling claw, 23 is a transfer section, 24 is a cleaner brush, 25 is an erase light, 26 is a transfer belt. 29 is a fixing device. Purification of the drawings (no change in content) Ul Now 6 6 1LI 14-η phase-7
Transmission number 11 I'L-Study quantity 6 River Toichi--bhD-, - Procedural amendment (method) % formula %: 1 Mr. Commissioner of the Patent Office
So: 1 Indication of the case Patent Application No. 337652 of 1990 2 Title of the invention Electrophotographic printing device 3 Relationship with the amendment person case Patent application Person in charge Office
2-6-2 Otemachi, Chiyoda-ku, Tokyo! i destination uc
iti) 0292-72-2125 (Admiration + MR1!
As shown in the engraving and attachment of the drawing originally attached to the application (no changes to the content).

Claims (1)

[Scope of Claims] 1. Surface potential adjusting means for adjusting the surface potential of the photosensitive drum before transfer; transfer means for transferring the toner image formed on the surface of the photosensitive drum onto paper; and In an electrophotographic printing apparatus comprising a peeling means for peeling off the photosensitive drum, a surface potential detection means for detecting the surface potential of the photosensitive drum before transfer, and a control device for controlling the surface potential adjusting means and the peeling means. and inputting an output signal of the photosensitive drum surface potential detecting means before transfer to the control device to control the surface potential adjusting means, the peeling means, or both the surface potential adjusting means and the peeling means. An electrophotographic printing device characterized by: 2. In claim 1, the surface potential adjusting means is controlled by an error signal obtained by comparing the output signal of the photosensitive drum surface potential detecting means before transfer with a reference surface potential signal. Electrophotographic printing equipment. 3. Claim 2, characterized by comprising means for storing a plurality of the reference surface potential signals corresponding to the type of paper, and means for specifying one of the plurality of reference surface potential signals. Electrophotographic printing equipment. 4. Claim 1, further comprising a storage means for storing the input signal characteristics of the surface potential adjustment means with respect to the output signal of the surface potential detection means, and accessing the storage means according to the output signal of the surface potential detection means to An electrophotographic printing apparatus characterized in that an input signal of a surface potential adjustment means is read out. 5. In claim 4, storage means for storing input signal characteristics of the surface potential adjustment means for the output signals of the plurality of surface potential detection means corresponding to the type of paper, and means for specifying one of them. An electrophotographic printing device comprising: 6. An electrophotographic printing apparatus according to claim 1, wherein the surface potential adjusting means is a light source whose amount of light can be adjusted. 7. An electrophotographic printing apparatus according to any one of claims 1 to 6, wherein the peeling means is a corona discharge device or a charger.