JPH0234883A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To improve separating performance of a recording paper by providing a pre-transfer exposure lamp (PTL) switchable between ON and OFF in the front position of a transfer device and controlling a separating current supplied to a separating device so that the ratio of a DC component superimposing to an AC component of the separating current can be changed. CONSTITUTION:When the PTL 4 is turned on during a copying operation, the switch circuit 21a of a separating device power source 21 is switched by a controlling part 20 so that the DC component of the separating current (a high voltage alternating current) supplied to the separating device 7 increases in the positive side. Then the PTL 4 is turned off, the switch circuit 21a is switched so that the DC component of the separating current supplied to the separating device 7 increases in the negative side. As a result, separating the recording paper is constantly achieved with a simplified constitution either when the PTL 4 is turned on or off.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to electrostatic recording devices such as electrophotographic copying machines, and in particular, a pre-transfer exposure lamp ( The present invention relates to an electrostatic recording device equipped with PTL.

[Conventional technology]

2. Description of the Related Art Conventionally, there is an electrostatic recording apparatus in which a pre-transfer exposure rung (hereinafter referred to as PTL) is provided between a developing process area and a transfer process area at the periphery of a photoreceptor. The PTL consists of a light source such as a cold cathode discharge tube or a neon tube, and a filter provided in front of the light source if necessary, and irradiates the photoreceptor carrying the toner image with light having a wavelength that the photoreceptor is sensitive to.

By providing a PTL and irradiating the photoreceptor, the effect of increasing the transfer efficiency and improving the separation performance is produced.

The quality of the toner image transferred to the other side is degraded due to blurring and shading. This is because the toner electrostatically adheres to the photoreceptor; the adhesion force is weakened when the toner is irradiated with PTL.

An electrostatic recording device using a selenium-based photoreceptor does not have good separation performance, and in order to ensure good separation performance, it is generally done to keep the PTL ON (lit) at all times during copying.

On the other hand, organic photoconductive photoreceptors (OPC) generally have better separation performance than selenium-based photoreceptors, so PT
Copying is being performed with L set to 0FF (light off). However, under conditions of high humidity, the transfer efficiency decreases and only copies of pale images are obtained, so a switch that can be operated by the operator is provided, and ON10
FF switching was done.

[Problem to be solved by the invention]

Conventionally, in the electrostatic recording device, PTL ON/
Regardless of the OFF, the separation performance of the recording paper from the photoreceptor was insufficient, and the recording paper sometimes got jammed at the separation part. There was a problem in that a mechanical separation claw had to be provided outside the electrical separation device. Furthermore, it was observed that there was a difference in separation performance depending on whether the PTL was ON or OFF.

The present invention solves these problems, improves electrical isolation performance with a simple configuration, and improves PTL ON10 F F
An object of the present invention is to provide an electrostatic recording device that can perform good separation regardless of the conditions.

[Means to solve the problem]

The above object is an electrostatic recording device in which a toner image on a photoconductor is transferred onto a recording paper by a transfer device, the recording paper is separated from the photoconductor by a separator, and then fixed. A pre-transfer exposure lamp is provided, and the pre-transfer exposure lamp can be switched ON/OFF,
This is achieved by an electrostatic recording apparatus characterized in that the ratio of the direct current component superimposed on the alternating current component of the separation current supplied to the separator is controlled to be changed in accordance with the switching.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 is a sectional view of main parts showing the configuration of an embodiment of the present invention, Fig. 2
FIG. 1 is a circuit diagram showing an example of a switch circuit provided in the separator power supply of FIG. 1.

In Fig. 1, ■ indicates, for example, an O
A photoreceptor on which a photosensitive agent made of PC is spread, 2 is a charger, L
is an exposure beam from an image exposure device such as a laser beam writing device or a scanning optical system; 3 is a developing device; 6 is a transfer device;
is the PTL (
7 is a separator, 8 is a fixing device, 9 is a cleaning device, 1O is a pre-charging erase lamp, 20 is a control unit that controls the operation of the entire device, and 21 is a switch circuit shown in FIG. A separator power supply 22 supplies high-voltage alternating current to the separator 7, and a lamp power supply 22 supplies power for lighting the PTL.

Next, the operation of the embodiment of the present invention shown in the above figure will be explained.

First, when a copy button on an operation panel (not shown) is pressed to start a copy operation, the photoreceptor 1 rotates in the direction of the arrow. The peripheral surface of the photoreceptor 1 has been uniformly erased from the charge by the pre-charging erasing lamp 10 and then uniformly charged by the charger 2. Therefore, as the exposure beam L is incident, the photoreceptor L is uniformly charged. , electrostatic latent images, such as a latent image on a document, are sequentially formed.

Thereafter, the electrostatic latent image on the photoreceptor l is transferred to the phenomenon device 3.
is developed into a visible toner image.

The photoreceptor l continues to rotate further and the toner image is exposed by PTL 4 if the humidity is high.

After that, the recording paper P is fed out one sheet at a time from a paper feed cassette (not shown), and the operation is performed based on a paper feeding timing signal so that the leading edge of the toner image on the photoreceptor L and the leading edge of the recording paper P are aligned. The paper is fed by the second paper feed roller 12 that rotates the paper. Thereafter, the toner image on the photoreceptor L is transferred onto the recording paper P by the action of the transfer device 6. The recording paper P separated from the photoreceptor l by the separator 7 is sent to the fixing device 8 via the conveying means 13, where the toner image is fused and fixed, and then ejected from the apparatus by a paper ejection roller.

On the other hand, the toner remaining on the photoreceptor 1 is cleaned by the cleaning device 9 to prepare for the next copy.

When turning on the PTL 4, the copy operation control unit 20 switches the switch circuit 21a of the separator power supply 21 to generate a separation current (high-voltage alternating current) supplied to the separator 7.
By increasing the DC component on the (+) side of PTL 4
When turning off the separation current supplied to the separator 7,
-) side to increase the DC component.
Switch. This switching operation is performed for the reasons described below.

Conventionally, in electrostatic recording apparatuses, as described above, a slight difference has been observed in the separation performance of the recording paper P from the photoreceptor l after toner image transfer between when the PTL is ON and when the PTL is OFF. Therefore, for an electrostatic recording device equipped with PTL4, PTL is 0.
Various experiments were conducted to find conditions for good separation of both N10F and F, and the following results were obtained.

The separation current supplied to the separator 7 is divided into an alternating current shown in FIG. 3(a) without superimposed direct current, an alternating current with direct current superimposed on the (+) side shown in FIG. 3(b), and an alternating current shown in FIG. (-) shown in C)
Currents a and b separate the alternating current with superimposed direct current on the side, respectively.
, c, and experiments were conducted on the separation performance of the recording paper P using the combinations of this separation current and PTL 4 being turned on and PTL 4 being turned OFF.

In the experiment, copies were made 1000 times under each condition using an OPC photoreceptor charged to (-) using 45g paper of size A4, and the number of times paper jams occurred due to poor separation in the separation section was counted. The results are shown in Table 1.

From the results shown in Table 1, when the PTL is turned off, the separation current C
It has been found that when the PTL is turned ON, the recording paper P can be separated very well by supplying a separation current.

As one method of superimposing direct current on alternating current, a switch circuit 21a shown in FIG. 2 is used.

In the figure, Sl and S2 are changeover switches and Di.

D2 is a diode.

When only the selector switch 31 is turned on, the diode D
Due to the action of I, a separation current C containing a (+) DC component is supplied, and when only the selector switch S2 is turned on, the diode S2 acts and a separation current C containing a -) DC component is supplied.

So, along with turning PTL 4 ON or OFF,
The changeover switches Sl and S2 are simultaneously switched under the control of the control unit 10 as shown in FIG.
When TL4 is ON, a separation current is applied to separator 7, but PT
When L4 is OFF, the separation current C is supplied to the separator 7, so that separation of the recording paper P can be ensured.

In the above embodiment, the photoreceptor is charged to the (-) side, but when the photoreceptor is charged to the (+) side, the polarity at the time of separation in the above description is reversed.

〔Effect of the invention〕

According to the present invention, as explained above, in an electrostatic recording device equipped with a PTL, an electrostatic recording device that can always perform complete separation of recording sheets with a simple configuration regardless of whether the PTL is ON or OFF. A recording device can be provided.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of main parts showing the configuration of an embodiment of the present invention, Fig. wc2 is a circuit diagram showing an example of a switch circuit equipped with the separator of Fig. 1 as a source, and Fig. 3 is a circuit diagram showing an example of a switch circuit equipped with the separator of Fig. FIG. 3 is a diagram showing a waveform of a supplied separation current. 1... Photoreceptor 2... Charger 3... Developing device 4... Pre-transfer exposure lamp (PTL) 6... Transfer device 7... Separator

Claims (1)

[Claims] An electrostatic system that develops the latent image formed on the photoconductor to form a toner image, transfers the toner image onto recording paper using a transfer device, separates the recording paper from the photoconductor using a separator, and then performs fixing. In the recording device, a pre-transfer exposure lamp is provided at a position before the transfer device, and the pre-transfer exposure lamp is turned ON/OFF.
An electrostatic recording apparatus characterized in that F switching is possible and, in accordance with the switching, the ratio of the DC component superimposed on the AC component of the separation current supplied to the separator is controlled to be changed.