JPS58121080A - Paper jam detecting device in cleaning device of copying machine - Google Patents

Abstract

PURPOSE:To reduce influence caused by stain and temperature and to simplify maintenance and management as compared with utilization of a photosensor by utilizing a variation of a corona current of a DC corona charging device, as a paper jam detecting device for preventing roll-in of a cleaning device. CONSTITUTION:A signal from an AC generator 20 is applied to a cleaning AC corona charging device 7 through an amplifier 21, and in front of the amplifier 21, a positive DC voltage power source 22 is connected to apply positive DC bias to this charging device 7. To a DC corona charging device 11, negative voltage is applied from a DC voltage power source 23 to keep the charging balance. In case when missed form caused by peel-off penetrates into the charging device 11, a corona current value is changed, and is voltage-converted by a current- voltage converting circuit 24 to compare with a reference value by a comparator 25, and a signal is sent to a paper jam signal generator 26 to generate a paper jam signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper jam detection device provided adjacent to an AC charging device for cleaning, in order to prevent duplicate sheets from being rolled into a photoreceptor cleaning device of a copying machine. .

In a copier, the transfer stage typically passes through a link.

A cleaning device using a cleaning brush or the like is provided to remove residual developer remaining on the surface of the photoreceptor after the copy paper is peeled off. Further, on the upstream side of this cleaning device, there is provided a round AC charging device for cleaning that weakens the electrostatic adhesion of the current agent to the photoreceptor.

Further, a paper jam detection device is also provided which detects when a copy sheet enters the cleaning area while remaining attached to the photoreceptor due to a release path, and prevents the copy sheet from being caught in the cleaning device.

The main part of a conventional copying machine incorporating one of such paper jam detection devices is shown in FIG. In FIG. 91, reference numeral 1 is a photosensitive drum, which is attached to a shaft 2 so as to rotate in the direction of arrow a. The surface of the photoreceptor drum is made of a photoconductive material, and the photoconductive surface is first uniformly charged by a charging device 3. The light writing of the original manuscript was blown out on the electrically conductive surface.

Charges in areas exposed to light are discharged, forming an electrostatic latent image. This electrostatic latent image is developed by a developing device 4 into a visible image. This visible image is attracted to the copy paper 6 from the surface of the photoreceptor by the transfer charging device 5.
transcribed into. The copy paper 6 supporting the visible image is sent along the paper transport path indicated by the arrow, and is transferred to a fixing device (not shown).
After being fixed, the paper is stored in a paper storage tray (not shown). - There is a lot of residual developer left on the surface of the photoreceptor, ζO1! The cleaning charging device 7 charges the surface of the photoconductor to which the A-group developer is attached, so that the photoconductor f of the developer is charged.
The adhesion force to the Ijc surface is weakened. Thereafter, the residual reagent is removed from the surface of the photoreceptor by a cleaning device consisting of a rotating brush 8. Between the cleaning charging device 7 and the cleaning device 8, there is provided the above-mentioned 9 paper jam detection device, for example, the photo sensor V9, which prevents the paper from passing through the paper conveyance path bt due to the separation of the legs after transfer. A signal is generated to completely stop the operation of the cleaning device 8 in order to detect the paper that has adhered to the body 1 and entered the cleaning area 11, and to prevent the paper from being caught in the cleaning device 8. The cleaned surface of the photoreceptor is completely erased of stains by the static elimination lamp 10, and then transferred to the charging device 3. Thereafter, the same process is repeated for the ninth time when the second copy at shadow is formed.

As the paper jam detector 9 to prevent paper from getting caught in the cleaning device 8, a photo sensor or a sonic switch is mainly used, but a photo sensor or a sonic switch is susceptible to temperature changes and dirt. There are drawbacks.

The present invention was made to solve these problems, and has a paper jam detection system that is less affected by dirt, temperature, etc., is easy to maintain, and has a longer lifespan than conventional paper jam detectors. The purpose is to provide equipment.

To achieve this object, the present invention includes a DC charging device, a means for detecting a change in the value of current flowing between the DC charging device and a photoreceptor to generate a paper jam detection signal, and an AC charging device for cleaning. % mold consists of a DC voltage by an II DC electric device and a means for applying a DC voltage of opposite polarity.

In general, if paper enters between the photoconductor and the corona charging device, for example, with an AC corona charging device, the change in the value of the corona current flowing between the charging device and the photoconductor is minute, but with DC corona charging The amount of change in the current value in the device is generally large, although it depends on the size of the paper, so it is possible to detect when paper enters between the photoreceptor and the corona charging device. However, the cleaning charge used in the above-mentioned cleaning device after paper separation is mainly AC charge. Therefore, in the present invention, a charging device is provided adjacent to the AC charging device, and when paper enters between the DC charging device and the photoreceptor, a current flows between the DC charging device and the photoreceptor. A paper jam is detected based on the change in the value. However, if a DC charging device is installed, the charging balance will be disrupted, so
This is compensated for by applying a DC voltage of opposite polarity to the DC voltage of the DC charging device to the cleaning AC charging device.

A nine paper tie detection device using this DC charging device is less affected by dirt, temperature, etc., is easy to maintain, and has a longer lifespan than a photo sensor or the like.

/ Examples of the present invention will be described below with reference to the drawings.

Figure W, 2 shows the copying machine shown in Figure 1 in which the paper jam detection device according to the present invention is incorporated, and the same elements as in Figure II/2 are given the same reference numerals. In FIG. 2, a corona charging device 11 for each RIIC is provided above the AC corona charging device 7 for cleaning. This Rona charging device is a DC corona charging device.
i is constant. Diagram IIIJ has the corona current value on the vertical axis and time on the horizontal axis, and is the same as in Diagram μ, FIG. 3, and FIG. 6, which will be described later. FIG. 7 shows a block diagram of the paper jam detection device according to the present invention. Referring to FIG.
- is added to the AC flL corner charging device 7 through the AC flL corner charging device 7.

A positive DC voltage power supply 22 is connected between the AC generator 20 and the amplifier 21, and therefore a positive DC bias is applied to the AC corona charging device 7 (see Figure ≠). , Direct ft, :F Rona charging device IIK supplies a negative voltage of opposite polarity to the positive voltage from the DC voltage power supply 22 II! An l#L voltage power supply 23 is connected. As can be seen from FIGS. 3 and 3, the polarity of the [a bias] of the AC corona charging device 7 is DC;
This is the opposite of 1. This maintains charge balance. When a sheet of paper that has been peeled off incorrectly enters between the photoreceptor 1 and the TGT style corona charging device 11, the value of the corona charge & is changed as shown in FIG. This change is converted into a voltage by the current-voltage conversion circuit 24. This voltage is compared with the base *fm by comparator 25 to determine if there is a paper jam condition.

FiIj1 when it is determined that the paper is in a state of
A signal is sent to a paper jam signal generator 26, which generates a paper jam signal. Incidentally, in Figure 6, the paper that was peeled off incorrectly is attached to the photoreceptor L and the AC corona charging device 70.
This figure shows the change in alternating current corona current when the corona current enters the gap.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, in the above embodiment, a negative DC voltage is applied to the DC corona charging device 11, and an AC corona charging device 11 is applied with a negative DC voltage. Although a positive @ current bias voltage is applied to the device 7, the polarity of this voltage may be reversed depending on the charging characteristics of the developer and the like.

As described above, the present invention utilizes all changes in the corona current of the DC corona charging device as a paper jam detection device to prevent the paper jam from being caught in the cleaning device. It is less affected by temperature, etc., and its maintenance is easy, so the number of visits by a service engineer can be reduced.

Furthermore, compared to photo sensors whose output decreases by 3 dB after 20,000 hours of use, their lifespan is longer, and cleaning frequency
Since a direct current/caustic voltage having a polarity opposite to that of the voltage applied to the DC corona charging device is applied to the L-fluora charging device, charging errors will not occur.

[Brief explanation of drawings]

FIG. 7 is a schematic diagram of a copying machine incorporating a conventional paper jam detection device. FIG. 82 is a schematic diagram of a copying machine incorporating a paper jam detection device ft according to the present invention. #! Figure 3 shows [15! 2 is a graph showing temporal changes in corona current in a normal state in a corona charging device. W, ≠ is a graph showing the temporal change in the Fc1 current in the AC corona charging device shown in FIG. 1I2 during normal operation. FIG. 3 is a graph showing temporal changes in corona current during paper winding in the DC corona charging device shown in FIG. FIG. 6 is a graph showing temporal changes in corona current during paper winding in the AC corona charging device shown in FIG. FIG. 7 is a block diagram of a paper jam detection device according to the present invention. l...Photoreceptor, 3@o...Charging device, 4...
・Current device, 5...-1...Transfer charging device%6...
...Paper. 7...Fist--Charging device for cleaning, 8...Life/Sei M! Apparatus, 9-... Photosen t110...- Static elimination device, 11-#... DC charging device, 20--.0. AC generator, 21-... Amplifier, 22.2311 ...,
・DC voltage power supply, 24...Current voltage conversion circuit, 2
5. Fist: Comparator, 2 (i memo, paper jam signal generator. Fig. 1 Fig. 2

Claims (1)

[Claims] In order to prevent the copy paper from getting caught in the photoreceptor cleaning device of the copying machine, paper 1! is installed adjacent to the AC charging device for cleaning. in the ifi detection device, a DC charging device, a means for detecting a change in the value of a current flowing between the DC charging device and the photoreceptor to generate a paper jam detection signal, and a means for generating a paper jam detection signal in the cleaning AC charging device; A paper jam detection device comprising means for applying a DC bias voltage of opposite polarity to the DC voltage applied to the @ current charging device.