JPH05188786A - Transfer and separation device for electrophotographic recorder - Google Patents

Abstract

PURPOSE:To prevent a failure in a transfer caused by the shock of a separation by suppressing the shock of the separation in such a manner that separating force when the leading edge part of a transfer form enters a separating part, is made small, and increasing transfer force when the tailing edge part of the transfer form passes through the transfer part CONSTITUTION:A current flows in a transfer wire 22 and separating wires 24 and 26 via electrodes 31a-31c and a tension spring 32, from a power source, at the time of transferring/separating. In the separating wires 24 and 26, the current is controlled so that the separating force of a first separating part 25 is smaller than that of a second separating part 27. Therefore, even if the leading edge of the transfer form enters the first separating part 25 from the transfer part 23, and the separation is executed, the shock of the separation is suppressed because the separating force is small. When the transfer form is further, carried. the transfer form is separated with ordinary great force, on the second separating part 27. Thus, the shock of the separation on the leading edge of the transfer form is suppressed, and the occurrence of an abnormal image caused by the skipping of the transfer on the leading edge part of the image, can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / separation device for an electrophotographic recording device applied to a copying machine, a laser printer or the like.

[0002]

2. Description of the Related Art FIG. 6 is a schematic configuration diagram of a conventional laser printer. In FIG. 6, a transfer sheet 2 fed from a sheet feeding device 1 in the direction of arrow A is timed by a pair of registration rollers 3. And is conveyed to the drum-shaped photoconductor 4.
The photosensitive member 4 is rotationally driven counterclockwise, and at that time, the surface is charged by the charging charger 5, and the laser optical system 6
Is irradiated with the laser beam L to form an electrostatic latent image on the surface. This latent image is visualized by toner as it passes through the developing device 7. This toner image is transferred onto the transfer paper 2 conveyed to the photoconductor 4 by the transfer / separation charger 8, and the transfer paper 2 that is in close contact with the photoconductor 4 is electrostatically separated. After that, the transfer paper 2 is conveyed to the fixing device 9, and the toner image on the transfer paper 2 is fixed by the fixing device 9 and is discharged to the discharge unit 10 in the direction of arrow B. On the other hand, after the toner image is transferred, the residual toner is removed by the cleaning device 11 having the cleaning blade 11a, and the removed toner is collected by the cleaning device 11.

FIG. 7 is an enlarged view of the transfer / separation charger shown in FIG. 6. In FIG. 7, the transfer paper in the paper path is superposed on the surface of the photoconductor 4 on which the toner image is formed, and the transfer paper is transferred from the rear surface. At the transfer unit 13, a charge having a polarity opposite to the charge of the toner is applied by corona discharge, and the toner is attracted to the transfer paper and separated.

At this time, the transfer paper comes into close contact with the photoconductor 4.
In order to separate this closely attached transfer paper from the photoconductor 4, an AC corona discharge is performed from the back surface of the transfer paper at the separating section 14 to neutralize (charge removal) the accumulated charge of the transfer paper, and the photoconductor 4 and the transfer paper Remove the adsorption force of.

In the figure, 15 is a transfer wire laid in the transfer section 13, 16 is a separation wire laid in the separation section 14, 17
Is a casing of the transfer / separation charger 8, and 18 is a transfer unit 13.
A partition plate for partitioning the separation section 14 from the separation section 14, and a separation guide 19 for preventing the transfer paper from entering the separation section 14.

FIG. 8 is a timing chart of on / off control in the transfer / separation charger, in which the transfer wire 15 and the separation wire 16 are turned on at the time of LOW to cause corona discharge, and turned off at the time of HIGH.

The amount of ions generated in the transfer section 13 and the separation section 14 is the same while the current is on. Therefore,
Meanwhile, the transfer force and the separation force of the transfer unit 13 and the separation unit 14 are the same.

FIG. 8 shows an example when one sheet is passed, and it is turned on at the start of sheet passing and turned off (strictly, a time margin is taken) after the end. Further, FIG. 9 shows an example of continuous sheet feeding, in which the sheet is turned on during the entire period of continuous sheet feeding and turned off after the sheet feeding is completed.

[0009]

In the above-mentioned conventional transfer / separation charger, the transfer paper closely attached to the photosensitive member 4 is
At the moment when the front end passes through the transfer unit 13 and enters the separation unit 14, the separation may occur, and the separation shock may be caused by the movement of the gap G between the transfer paper and the transfer / separation charger 8. At this time, in the transfer paper portion located in the transfer portion 13,
The adhesiveness with the photosensitive member 4 is momentarily lost, the transfer omission occurs, and an abnormal image is generated at the leading end of the image. The separation shock may also occur at the moment when the trailing edge of the transfer paper leaves the transfer unit 13.

During continuous paper feeding (including one-sided double-sided paper feeding), since the transfer unit 13 and the separating unit 14 are turned on during the entire continuous paper feeding, the life of the photoconductor caused by corona discharge. The amount of ozone that adversely affects

An object of the present invention is to provide an electrophotographic recording apparatus capable of preventing the generation of an abnormal image at the edge of an image, suppressing generation of ozone during continuous sheet feeding, and eliminating troubles during transfer and separation operations. It is to provide a transfer / separation device.

[0012]

In order to achieve the above object, the first means of the present invention is a transfer portion for transferring a toner image formed on the surface of a photoreceptor to a transfer paper by corona discharge, and a transfer portion. In a transfer / separation device of an electrophotographic recording apparatus, which is composed of a separation unit that separates a transfer paper from a photoconductor by corona discharge later, the separation unit is configured so that the separation force on the transfer unit side becomes small. And

A second means is that the separating part in the first means is composed of a plurality of separating parts having different separating forces,
It is characterized in that they are arranged in order from the separation portion having the smallest separation force toward the transfer portion.

The third means includes a transfer portion for transferring the toner image formed on the surface of the photoconductor to the transfer paper by corona discharge, and a separation portion for separating the transfer paper after transfer from the photoconductor by corona discharge. Transfer of an electrophotographic recording device
In the separating device, the separating force of the separating unit is increased stepwise between the sheets of paper.

The fourth means includes a transfer portion for transferring the toner image formed on the surface of the photoconductor to the transfer paper by corona discharge, and a separating portion for separating the transfer paper after transfer from the photoconductor by corona discharge. Transfer of an electrophotographic recording device
In the separating device, the transfer force of the transfer unit is increased stepwise between the sheets of paper.

The fifth means includes a transfer part for transferring the toner image formed on the surface of the photoconductor to a transfer paper by corona discharge, and a separating part for separating the transfer paper after transfer from the photoconductor by corona discharge. Transfer of an electrophotographic recording device
In the separation device, the separation force of the separation unit is zero between the sheets in continuous sheet passage or smaller than that during sheet passage.

Further, a sixth means comprises a transfer section for transferring the toner image formed on the surface of the photoconductor to a transfer paper by corona discharge, and a separation section for separating the transfer paper after transfer from the photoconductor by corona discharge. In the transfer / separation device of the electrophotographic recording apparatus, the transfer force of the transfer unit is zero between the sheets during continuous sheet passage or smaller than that during sheet passage.

[0018]

According to the above first and second means, when the leading end of the transfer paper enters the separating portion from the transferring portion, a small separating force is first applied to the leading end, so that the transferring paper is only slightly separated. Therefore, it is possible to suppress the separation shock of the transfer paper,
Since (normally appropriate) separation force is applied, reliable separation can be performed and transfer failure due to the separation shock can be prevented.

According to the third means, when the leading edge of the transfer paper enters the separating portion, the separating force is small, so that
Separation shock can be suppressed and transfer defects can be prevented.

According to the fourth means, even if a separation shock occurs at the moment when the trailing edge of the transfer paper leaves the transfer section, the transfer force at the trailing edge of the transfer paper increases, so that the transfer due to the separation shock occurs. Defects can be prevented.

Further, according to the fifth and sixth means, the separation force or the transfer force between the transfer sheets in the separation charger or the transfer charger is zero during continuous sheet feeding, or is smaller than that during sheet feeding to suppress corona discharge. By doing so, the generation of ozone is reduced and the adverse effect on the photoconductor and the like is prevented.

[0022]

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

FIG. 1 is a block diagram of the first embodiment of the present invention, FIG.
FIG. 3 is a configuration diagram showing an internal configuration of the first embodiment, 20 is a transfer / separation charger, 21 is a drum-shaped photosensitive member, and 22 is a transfer unit.
A transfer wire erected in 23, 24 a single separating wire erected in the first separating section 25 adjacent to the transferring section 23, and 26 a second separating section 27 adjacent to the first separating section 25. Two separation wires installed inside, 28 is a casing of the transfer / separation charger 20, 29 is a partition plate for partitioning the transfer section 23, the first separation section 25, and the second separation section 27, and 30 is the first , A separation guide for preventing the transfer paper from entering the second separation units 25, 27.

In FIG. 2, 31a, 31b and 31c are connected to a power source (not shown), and tension springs 32 are respectively attached to the transfer wire 22 and the separation wires 24 and 26.
The electrodes are electrically connected via.

Next, the operation of the above first embodiment will be described.

At the time of transfer / separation, a current flows from the power source to the transfer wire 22 and the separation wires 24 and 26 via the electrodes 31a to 31c and the tension spring 32. In the separating wires 24 and 26, the current is controlled so that the first separating portion 25 has a smaller separating force than the second separating portion 27. In this embodiment, this is done by superimposing an AC component and a DC component.

Therefore, the leading edge of the transfer paper is transferred from the transfer section 23 to the first position.
Even if it enters the separating section 25 and is separated, the separating force is small, so that the separating shock is suppressed. Then, when the transfer paper is further conveyed, the second separation unit 27 separates the transfer paper with a normal large separating force.

By gradually releasing (separating) the contact between the photoconductor 21 and the transfer sheet in this manner, the separation shock at the leading end of the transfer sheet is suppressed, and the transfer dropout occurs at the leading end of the image. Prevents the generation of abnormal images.

FIG. 3 is a block diagram of the second embodiment of the present invention, in which members corresponding to those described with reference to FIG.

In FIG. 3, reference numeral 35 is a transfer driving section for driving and controlling corona discharge and transfer force in the transfer section 13, and 36 is a separating section 14.
Separation drive unit that drives and controls corona discharge and separation force at
Reference numeral 37 is a control unit that controls the operation timing of the transfer drive unit 35 and the separation drive unit 36.

FIG. 4 is a transfer / separation timing chart of the second embodiment. Each time one sheet of transfer paper passes through the transfer / separation charger 8, the leading edge of the transfer paper passes through the transfer section 13 and the separation section 14 For a short time after the start of the separation, the separation current ( _IB1 ) smaller than the normal value (a value that allows proper separation) is passed to gently separate the photosensitive member 4 (first separation force). Then, when the transfer sheet is further conveyed, the tip of the photoconductor 4 is reliably separated (second separating force) so that the tip of the photoconductor 4 is separated to the normal value at a timing set before passing through the separating section 14. Electric current
(I _B2 : I _B2 > I _B1 ) is flown.

At the moment when the trailing edge of the transfer paper leaves the transfer portion 13, a transfer current larger than the normal value (value at which proper transfer is performed) is generated.
( _{IT 2} ) is flown to increase the transfer force in order to correct the decrease in the transfer force due to the weak adhesion to the photoconductor 4.
(Second transfer force). The time for flowing the transfer current I _T2 is

[0033]

[Equation 1]

It is assumed that From the start of sheet passing to the time when the transfer current I _T2 is supplied, a transfer current of a normal value (IT ₁ : IT ₁ < _{IT 2} ) is supplied so that the normal transfer force (first transfer force) is applied.

FIG. 5 is a timing chart of transfer / separation at the time of continuous sheet feeding (including double-sided sheet passing by one sheet). Until the next transfer sheet at the transfer / separation charger 8 at the time of continuous sheet feeding is passed. At each sheet interval P, the current to the transfer unit 13 and the separation unit 14 is turned off (the current value may be reduced), and the corona discharge is stopped.

By doing so, it is possible to reduce the amount of ozone that is generated in large quantities during continuous paper feeding, and prevent the life of the photoreceptor 4 from being affected by ozone.

In the above embodiment, the number of the separating portions installed is two, and the change of the transfer force and the separating force is two stages. However, it is more preferable to set two or more stages. Transfer and separation operations can be performed.

[0038]

As described above, according to the first to third means of the present invention, the separating force when the leading edge of the transfer paper enters the separating portion is reduced to suppress the separating shock. In this way, the transfer failure of the electrophotographic recording apparatus can be prevented, and according to the fourth means, the transfer force when the trailing edge of the transfer paper leaves the transfer section is increased to prevent the transfer failure due to the separation shock. -Provide a separating device.

Further, according to the fifth and sixth means, the separation force or the transfer force at the time of continuous paper feeding is set to zero or smaller than that at the time of paper feeding to suppress the corona discharge, so that the generation of ozone is prevented. Since the number can be reduced, it is possible to provide a transfer / separation device of an electrophotographic recording device which can prevent the adverse effects of the photoconductor and the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of a transfer / separation device of an electrophotographic recording apparatus of the present invention.

FIG. 2 is a configuration diagram showing an internal structure of the first embodiment of FIG.

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is a timing chart of transfer / separation according to the second embodiment.

FIG. 5 is a timing chart of transfer / separation during continuous paper feeding.

FIG. 6 is a schematic configuration diagram of a conventional laser printer.

FIG. 7 is an enlarged view of the transfer / separation charger of FIG.

FIG. 8 is a conventional transfer / separation timing chart.

FIG. 9 is a timing chart of transfer / separation during conventional continuous paper feeding.

[Explanation of symbols]

4, 21 ... Photosensitive body, 8, 20 ... Transfer / separation charger,
13, 23 ... Transfer unit, 14, 25, 27 ... Separation unit, 15, 22 ... Transfer wire, 16, 24, 26 ... Separation wire, 35 ... Transfer drive unit, 36 ... Separation drive unit, 37 ... Control unit.

Claims (6)

[Claims] 1. An electrophotographic recording comprising a transfer section for transferring a toner image formed on the surface of a photoconductor to a transfer paper by corona discharge, and a separation section for separating the transfer paper after transfer from the photoconductor by corona discharge. In the transfer / separation device of the apparatus, the transfer / separation device of the electrophotographic recording apparatus is characterized in that the separation portion is configured so that the separation force on the transfer portion side is small. 2. The electrophotographic recording apparatus according to claim 1, wherein the separation unit is composed of a plurality of separation units having different separation forces, and the separation units having smaller separation forces are sequentially arranged closer to the transfer unit. Transfer / separation device. 3. An electrophotographic recording comprising a transfer section for transferring a toner image formed on the surface of a photoreceptor to a transfer paper by corona discharge, and a separation section for separating the transfer paper after transfer from the photoreceptor by corona discharge. In the transfer / separation device of the apparatus, the separation force of the separation unit is increased stepwise between the sheets of paper, and the transfer / recording device of the electrophotographic recording device is characterized. 4. An electrophotographic recording comprising a transfer part for transferring a toner image formed on the surface of a photoconductor to a transfer paper by corona discharge, and a separation part for separating the transfer paper after transfer from the photoconductor by corona discharge. In the transfer / separation device of the apparatus, the transfer force of the transfer section is increased stepwise between the sheets of paper, and the transfer / recording apparatus of the electrophotographic recording device is characterized. 5. An electrophotographic recording comprising a transfer section for transferring a toner image formed on the surface of a photoconductor to a transfer paper by corona discharge, and a separation section for separating the transfer paper after transfer from the photoconductor by corona discharge. The transfer / separation device of an electrophotographic recording apparatus, wherein the separation force of the separation portion is zero between sheets in continuous sheet passage or smaller than that during sheet passage. 6. An electrophotographic recording comprising a transfer section for transferring a toner image formed on the surface of a photoreceptor to a transfer sheet by corona discharge, and a separation section for separating the transfer sheet after transfer from the photoreceptor by corona discharge. In the transfer / separation device of the apparatus, the transfer force of the transfer portion is zero between sheets in continuous sheet passing or smaller than that at the time of sheet passing.