JPH0240677A - Image forming method - Google Patents

Abstract

PURPOSE:To surely transfer and separate by discharging the end part of an unrecorded sheet from a corona discharging device, peeling the end of the sheet from a drum, and transferring and discharging onto a remaining part, when the unrecorded sheet is fed from such as a feeding means and comes into contact with the photosensitive drum. CONSTITUTION:A paper-feeding part 21 provided on the lower part of a device main body 1 of an image forming device feeds the unrecorded sheet 6 to a separating transfer means 7 by the command of a micro-computer 60 in synchronization with the moving of an exposing unit 10 and the rotation of the photosensitive drum 2. This means 7 feeds the transferred and separated sheet 6 from a carrying part 22 to a fixing part 23 and feeds out the fixed sheet on an outer paper discharging tray 28. This means 7 is provided with the corona discharging device 71 holding a corona discharging wire 72 on which is impressed high voltage. A switch 76 is switched by the indication of the computer 60. The end of the unrecorded sheet is separated from the drum 2 by separating corona discharge at the side of an AC power 74 and the remaining part is transferred and discharged at the side of a DC power 75.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming method for forming an image in a copying machine or the like by transferring a toner image on a photoreceptor drum onto a sheet of paper.

[Prior Art] Conventionally, while a photoreceptor drum on which a toner image has been formed is brought into contact with unrecorded paper, a transfer device applies corona discharge with a polarity opposite to the charged polarity of the toner from the back side of the unrecorded paper. to transfer the toner image to the paper. A separating device then separates the transferred paper from the photoreceptor drum by applying an alternating current corona discharge to the back side of the transferred paper.

In addition, as another conventional device, a device has been proposed in which a transfer device and a separation device are integrated, and a single high-voltage power supply provides a transfer function and a separation function (Japanese Unexamined Patent Publication No. 6-16-16).
9873).

[Problem to be solved by the invention a] However, in the case where a separation device is provided after the transfer device, the transfer corona discharge and the separation corona discharge are separated from each other on the back side of the transfer paper that is in contact with the photoreceptor drum surface. interfere with each other. Therefore, if the separation effect is too strong, the transfer will be incomplete and a defective image will occur, and if the transfer effect is too strong, separation may not occur.

Furthermore, since it is necessary to arrange two devices, a transfer device and a separation device, there is a problem that it takes up too much space, and there is also a limit to the cost reduction.

Furthermore, when using a device that integrates the transfer device and separation device described above, there is no problem with space, but the transfer corona discharge action and the separation discharge action work simultaneously on the back side of the transfer paper, and the toner If the images are scattered, image deterioration such as poor transfer will occur.

SUMMARY OF THE INVENTION In view of the problems of the conventional transfer technology, it is an object of the present invention to provide an image forming method that is inexpensive, compact, and capable of producing high-quality images.

[Means for Solving the Problems] The present invention as defined in claim 1 brings a photosensitive drum on which a toner image has been formed into contact with unrecorded paper fed by a paper feeding means, and transfers the image to the unrecorded paper by corona discharge. In an image forming method that performs
Peeling is performed by performing peeling corona discharge on the leading edge portion of the unrecorded paper, and transfer corona discharge is performed on the remaining portion of the unrecorded paper.

[Operation] Since no image is formed on the leading edge of the paper, there is no need for transfer discharge, and in order to separate the paper from the photosensitive drum, it is necessary to separate even the leading edge of the paper from the photosensitive drum. If possible, the remaining portion will peel off naturally. Therefore, with the above configuration, the present invention performs separation discharge without performing transfer discharge on the leading edge of the paper, and performs transfer without performing separation discharge on the remaining portion of the paper. It performs electric discharge.

[Examples] The present invention will be described below based on drawings showing examples thereof.

FIG. 1 is a schematic sectional view of an image forming apparatus used to carry out the image forming method of the present invention.

In the figure, inside the apparatus main body 1, there is a photosensitive drum 2 on whose surface a photoconductive material is formed on which a latent image of an original image is formed.
is rotatably installed. Around the photoreceptor drum 2, along the direction of rotation, there is a charging section 3, an exposure section 4 that is irradiated with image light, a developing section 5 that develops the latent image on the photoreceptor drum 2, and the developed image. Members such as a transfer separation section 7 for transferring and separating toner onto the paper 6, a cleaning section 8 for removing toner remaining on the photoreceptor drum 2, and a static elimination section 9 are arranged in this order.

A document cover 15 for holding the document 12 and a contact glass 1 on which the document 12 is placed are provided on the upper part of the device main body l.
4 is attached, and below the contact glass 14, an exposure unit 10 equipped with an exposure lamp 11 is arranged. A mirror unit 13 is provided on the side of the exposure unit 10, and the image light incident from the exposure unit 10 is transferred to an imaging lens 13 in the center of the apparatus main body 1.
lead to. The reflecting mirror 17 is a mirror that irradiates the photosensitive drum 2 with the image light that has passed through the imaging lens 16 . Additionally, a switch 70 for turning the power on and off is provided on the main body of the device.
A microcomputer 60 is provided as an example of a control means for controlling the entire apparatus body l.

Furthermore, a paper feed section 21 is provided at the bottom of the apparatus main body l. A paper cassette 29, a roller 30 for feeding out the paper 6, a registration switch 32, and a registration roller 31 for transporting the paper 6 are arranged in the paper feeding section 21. The paper feed section 21 feeds the unrecorded paper 6 to the transfer separation section 7 in synchronization with the movement of the exposure unit 10 and the 20 rotations of the photosensitive drum l, according to instructions from the microcomputer 60. It is something.

Further, the paper 6 that has been transferred and separated by the transfer separation section 7 is sent to the fixing section 23 by the conveyance section 22 . The fixed transfer paper is sent out onto an external paper discharge tray.

FIG. 2 is a block diagram showing details of the transfer separation section 7 of FIG. 1.

In the figure, 71 is a corona discharger, 72 is a corona discharge line to which a high voltage is applied, and 73 is a high voltage power source that generates the high voltage. The high voltage power supply 73 is an AC power supply 74
and a DC power source 75, which is connected to the corona discharge line 72 via a switch 76. The switch 76 is turned on and off via the interface 20 based on instructions from the microcomputer 60. Further, the paper feed section 21 is controlled by its microcomputer 60.

Next, the image forming method according to the present invention will be explained together with the operation of the above embodiment.

The paper feed unit 21 feeds the unrecorded paper 6 from the paper feed cassette 29 to the transfer separation unit 7 in accordance with the movement of the exposure unit 10 and the rotation of the photosensitive drum 20 according to instructions from the microcomputer 60. Send it in.

When the unrecorded paper 6 is brought into contact with the photoconductor tram 2 and its leading edge reaches the transfer separation unit 7, the transfer separation unit 7 switches the switch 76 to the AC power source according to instructions from the microcomputer 60. 74 side, and a high AC voltage is applied to the corona discharge wire 72. FIG. 3 is a waveform diagram showing this situation. The width of the tip portion to which the high AC voltage is applied is, for example, 5 mm. Due to the separated corona discharge caused by this high AC voltage, the leading edge of the paper 6 is moved to the photoreceptor drum 2.
Separate from.

Next, when the remaining portion of the paper 6 reaches the transfer separation section 7,
The microcomputer 60 turns on the switch 76 to the DC power supply 75 side, and as shown in FIG. 3, a high DC voltage is applied to the corona discharge wire 72. By applying this high DC voltage, transfer corona discharge is performed, and the toner image adhered to the photosensitive drum 2E is transferred to the paper 6.

Therefore, since the transfer corona discharge and the separation corona discharge are not performed at the same time, they do not interfere with each other.

In addition, by applying an alternating current voltage in a state where the paper 6 is not present, the surface image transfer/separation unit 7 can eliminate static electricity from the photoreceptor drum 2 .

FIG. 4 is a detailed timing chart of the above-mentioned operation.

In the same figure, "registration SW" refers to the paper feed section 2.
1 shows the detection timing of the resist switch 32, in which the paper 6 is sent out from the paper feed cassette 29, turns on when the leading edge reaches it, and turns off when the trailing edge comes out. "Ejection SWJ indicates the detection timing of the ejection switch 19, which is turned on when the paper 6 is ejected from the fixing unit 23 and the leading edge starts to be ejected, and turned off when the trailing edge comes out.

The "main motor" indicates the drive timing of the motor that rotates the photosensitive drum 2, and is turned on when printing starts. "Paper feed clutch" refers to the operation timing of the clutch that drives the paper feed roller 30, which is turned on at the start of printing, and "registration clutch" refers to the operation timing of the clutch that drives the registration roller 31. "Main charging" refers to the timing at which the charger 3 charges. What is rAC high pressure?
The timing at which the transfer separation section 7 generates an alternating voltage, r
"DC high voltage" indicates the timing at which the transfer separation section 7 generates a DC voltage. "Start of exposure" indicates the timing at which the exposure unit 10 starts exposure.

Further, T+ is the time from when the registration switch 32 is turned on until the paper 6 hits the registration roller 31.

T2 is the time until the main charging start position on the photosensitive drum 4 reaches the exposure section 4. T3 is the time from when the registration clutch is turned on until the transfer start portion of the paper 6 comes to the transfer position.

As is clear from the figure, the transfer start portion of the paper 6 (paper 6
When the leading edge of the remaining portion (excluding the leading edge) reaches the transfer position (transfer separation unit 7), a DC high voltage is applied and transfer corona discharge is performed, so that the toner image is formed in the area after the transfer start point. transcribed. Furthermore, when the portion before the transfer start portion, that is, the leading edge of the paper 6, is at the transfer position, as is clear from the figure, an AC high voltage is applied and separate corona discharge is performed. Therefore, the leading end of the paper 6 is separated from the photosensitive drum 2.

[Effects of the Invention] As described above, the image forming method according to the present invention performs separated corona discharge on the leading edge of the paper and transfer corona discharge on the remaining part of the paper, so it is inexpensive. Moreover, it is small and can obtain high quality images.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an image forming apparatus used in an image forming method according to an embodiment of the present invention, FIG. 2 is a front view of a separation transfer section of the image forming apparatus, and FIG. , a voltage waveform diagram of the separation transfer section of the image forming apparatus, and FIG. 4 is a timing chart of each part of the image forming apparatus.

Claims (2)

[Claims] (1) In an image forming method in which a photosensitive drum on which a toner image has been formed is brought into contact with unrecorded paper fed by a paper feeding means, and an image is transferred to the unrecorded paper by corona discharge, the unrecorded paper is unrecorded by the paper feeding means. When the paper is conveyed and brought into contact with the photosensitive drum, the corona discharge device performs peeling corona discharge on the leading edge of the unrecorded paper to perform peeling, and the remaining portion of the unrecorded paper is , an image forming method characterized by performing transfer corona discharge. (2) Image forming according to claim 1, characterized in that it is determined that the leading edge of the unrecorded paper has reached a corona discharge device by using the control timing of the control means that controls the paper feeding means. Method.