JPH0356981A - Transfer pressure control method - Google Patents

Abstract

PURPOSE:To prevent the mechanical deterioration and the breakage of a photosensitive body and the occurence of transfer failure by weakening the pressure of a transfer roller pressing the photosensitive body at the time of starting transferring a toner picture, and gradually increasing the pressure. CONSTITUTION:A driving means 14 is controlled by a pressure controlling means 10 so that the pressure of a press-contacting means 13 is increased according to a driving instruction outputted by a control means 15. Consequently, since a supporting shaft 7 is pushed up in the direction of an arrow A with weak force, a printing medium 12 is pressed against an image carrier 11. Since the pressure of the driving means 14 is increased after the pressing is started, the printing medium 12 is pressed against the image carrier 11 by the press- contacting means 13 with the increased pressure. Thus, the deterioration and the breakage of the photosensitive drum 1 and the occurence of the transfer failure are prevented.

Description

[Detailed Description of the Invention] [Summary] When transferring a toner image developed by attaching a donor to a latent image formed on an image carrier onto paper, the paper is pressed against the image carrier and a transfer voltage is applied. In the transfer device that applies the voltage,
Regarding the transfer pressure control method that does not apply impact to the image carrier and does not cause transfer defects when paper is pressed against the image carrier, the purpose is to prevent deterioration and damage of the photosensitive drum and transfer defects. and a pressure-bonding means for pressure-bonding the printing medium onto the image-bearing body when transferring the developed toner image by adhering toner to the latent image formed on the image-bearing body onto the printing medium; In a transfer apparatus comprising a driving means for driving a means to press the printing medium against the image carrier with a predetermined pressure, and a control means for giving a driving instruction to the driving means, the driving instruction sent by the control means is Based on the above, a pressure control means is provided for controlling the driving means to increase the pressing pressure of the pressing means, and the pressing means is caused to press the printing medium against the image carrier when toner image transfer is started. After that, the pressing pressure is increased.

[Industrial application field]

The present invention relates to a transfer device that presses paper onto an image carrier and applies a transfer voltage when transferring a developed toner image onto paper by attaching toner to a latent image formed on the image carrier. In particular, the present invention relates to a transfer pressure control method that does not apply impact to the image carrier and prevent transfer defects when pressing paper onto the image carrier.

2. Description of the Related Art In an electrophotographic recording device such as a laser printer, a toner image formed on a photoreceptor is electrostatically transferred onto a sheet of paper to obtain a record. In this case, the toner image transfer method includes a corona transfer method, a roller transfer method, a belt transfer method, and the like. Among these, the roller transfer method and belt transfer method are
Since a corona discharger is not used, there is no need for a high-voltage power source of several kilovolts, and there is an advantage that no ozone is generated, which has an odor and is harmful to the human body.

However, in the roller transfer method and belt transfer method, when transferring a toner image, the paper is pressed against the photoreceptor and a transfer voltage is applied to the paper, and when the toner image is not being transferred, the roller or belt is in contact with the photoreceptor. Therefore, at the start of transfer, the roller or belt is moved to press the paper against the photoreceptor.

At this time, it is necessary to prevent the roller or belt from colliding with the photoreceptor with strong force.

[Conventional technology] FIG. 4 is a block diagram illustrating an example of the prior art.

2 is a photosensitive drum; 2 is a toner image formed on the photosensitive drum 1; 3 is paper and toner image 2 on photosensitive drum 1
is electrostatically transferred. Reference numeral 4 denotes a transfer roller, which is generally made of a conductive cylinder. Reference numeral 5 denotes a power source that supplies voltage for electrostatic transfer to the transfer roller 4.

6 is a fulcrum shaft, and 7 is a support, which connects the fulcrum shaft 6 and the freely movable transfer roller 4. 8 points the pillar 7 with arrow A-B
This is a power source that presses the transfer roller 4 against the photosensitive drum 1 by moving it in the direction of , and generally an electromagnetic solenoid, a motor, or the like is used.

A control circuit 9 provides an on/off signal to the power source 8 to instruct the transfer roller 4 to be brought into contact with the photosensitive drum 1 or to be released from the photosensitive drum 1.

If the photosensitive drum 1 and the transfer roller 4 are in constant contact, the characteristics of the photosensitive drum 1 will deteriorate, so when the toner image 2 is not transferred, the photosensitive drum 1 and the transfer roller 4 are separated. .

When the toner image 2 is transferred, the printing start position of the printing plate 3 that has been conveyed in the direction of arrow C and the toner image that has been conveyed in the direction of arrow D by the rotation of the photosensitive drum 1 are selected. Immediately before the transfer roller 2 reaches the position of the transfer roller 4, the power source 8 activated by the ON signal sent from the control circuit 9 pushes up the column 7 in the direction of arrow A, so that the transfer roller 4 transfers the transfer roller 3 to the photosensitive drum. At the same time, the toner image 2 is electrostatically transferred to the cover 3 because the transfer voltage supplied by the power source 5 is applied to the cover 3.

FIG. 5 is a diagram illustrating the operation of FIG. 4.

Pressure is plotted on the vertical axis and time is plotted on the horizontal axis. At the moment when the control circuit 9 sends an on signal to the power source 8, the pressure with which the transfer roller 4 presses the transfer roller 3 against the photosensitive drum 1 is at its maximum. The maximum value of the pressure continues until the moment when the control circuit 9 sends an off signal to the power source 8 and the power source 8 pushes down the column 7 in the direction of the arrow B, and the power a8 The pressure becomes zero at the moment (2) when the pillar 7 is pressed down.

[Problem to be solved by the invention]

In conventional technique 44i, the transfer roller 4 is instantly pressed against the photosensitive drum 1 with strong pressure, which may cause mechanical deterioration and damage to the photosensitive drum 1, and furthermore, the transfer roller 4 is instantly pressed against the photosensitive drum t. Therefore, there is a problem in that the transfer roller 4 bounces due to the elasticity of the conductive cylinder of the transfer roller 4, causing the jig 3 to vibrate and causing a transfer failure.

In view of these problems, the present invention prevents deterioration of the photosensitive drum 1 by preventing impact from being applied to the photosensitive drum 1 and preventing the transfer roller 4 from bouncing when the transfer roller 4 is pressed against the photosensitive drum 1. The purpose is to prevent damage and transfer defects.

[Means to solve the problem]

FIG. 1 is a block diagram illustrating the principle of the present invention.

In FIG. 1, a pressure pressure 1B means 10 is added to FIG. l4
corresponds to the power source 8, and the control means 15 corresponds to the control circuit 9, respectively.

The pressure control means 10 controls the drive means 14 to increase the pressing pressure of the crimping means 13 based on the drive instruction sent by the control means 15.

Therefore, the driving means 14 pushes up the column 7 in the direction of the arrow A with a weak force, so that the pressing means 13 presses the printing medium 12 against the image carrier 11. After the driving means 14 is pressed,
In order to increase the pressing pressure, the pressing means 13 presses the printing medium 2 against the image carrier 11 with increased pressure.

[Operation] With the above configuration, the pressure control means 10 increases the driving force of the drive means 14 based on the drive instruction from the control means 15, so the pressure bonding means 13 holds the image on the printing medium 12 with strong pressure. It is crimped onto the body 11.

Therefore, the pressure bonding means 13 does not instantly press the printing medium l2 against the image carrier 11 with a strong force, so that the image carrier 11 is not subjected to impact or pounding.

Therefore, mechanical deterioration and damage to the image carrier 11 can be prevented, and transfer defects can also be prevented.

〔Example〕

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 3 is a diagram illustrating the operation of FIG. 2.

The same reference numerals as in FIG. 4 indicate the same functions. Figure 2 (a
) transfers the transfer roller 4 to the photosensitive drum 1 with gradually increasing pressure.
This shows the case where it is pressed against the The control circuit 9 sends an on signal to the integrating circuit 16, as shown in (2) in FIG. 3(a).

For example, when the integrating circuit l6, which is composed of an operational amplifier, a resistor, and a capacitor, receives an ON signal, the level gradually increases as shown in Transistor 1
Send on 7.

Therefore, the transistor 17 gradually increases the current flowing from the power source 1 through the electromagnetic solenoid 18. When the electromagnetic solenoid 18 receives a current of a level that enables it to operate, it pushes the column 7 in the direction of the arrow A. Therefore, as shown in Fig. 3~), if the vertical axis represents the pressure and the horizontal axis represents the time, then At the start of the transfer shown in (2), the transfer roller 4 presses the cover 3 onto the photosensitive drum 1 with a weak pressure.

The electromagnetic solenoid 18 pushes up the pillar 7 with a force that gradually increases until a specified value of current flows.
The transfer roller 4 presses the paper 3 onto the photosensitive drum 1 with gradually increasing pressure.

Therefore, when the integrating circuit 16 sends out the maximum level signal, the transfer roller 4 presses the transfer roller 3 onto the photosensitive drum l with a predetermined pressure, as shown in (2) in FIG. 3(b), and the control circuit 9 An off signal is sent, and the transfer roller 4 is pressed against the photosensitive drum 1 with a predetermined pressure until the level of the signal sent from the integrating circuit 16 to the transistor 17 becomes zero.

FIG. 2(b) shows a case where the transfer roller 4 is pressed against the photosensitive drum 1 with a pressure that gradually increases. As shown in FIG. 3(C), the control circuit 19 switches the on signal ■ to the switching circuit 2.
Send to 0.

When the switching circuit 2.0 receives the ON signal (2), it sends the current supplied from the low voltage power supply vL to the electromagnetic solenoid 18. Therefore, a current smaller than the specified value flows through the electromagnetic solenoid 18 and pushes up the support column 7 in the direction of arrow A with a weak force. As shown in FIG. 3(d), the vertical axis shows pressure and the horizontal axis shows time. Then, at the start of the transfer shown in (3), the transfer roller 4 presses the cover 3 onto the photosensitive drum 1 with a weak pressure.

When a predetermined time has elapsed, the control circuit 19 stops sending out the on signal (2), and at the same time sends out the on signal (2) to the switching circuit 20, as shown in (2) in FIG. 3(C). Switching circuit 2
0 stops receiving the ON signal (2), and when the ON signal (2) is input, the current supplied from the high voltage power supply (2) A is sent to the electromagnetic solenoid 18.

Therefore, a specified value of current flows through the electric solenoid 18, pushing up the pillar 7 with a force that gradually becomes stronger, and the transfer roller 4 is activated at a predetermined pressure as shown in [phase] in FIG. 3(d). Press @3 onto the photosensitive drum 1.

Then, the transfer roller 4 is pressed against the photosensitive drum 1 with a predetermined pressure until the control circuit 19 stops sending out the ON signal (2).

FIG. 6 is a diagram illustrating an image recording apparatus to which the present invention is applied.

FIG. 6(a) uses a roller transfer method, and FIG. 6(a) uses a belt transfer method, without using any corona discharger.

In FIG. 6(a), 21 is an endless photosensitive film. This photosensitive film 21 has a thickness of 1 (10 μm
ITO on a transparent substrate of polyethylene terephthalate
This is a functionally separated organic photoreceptor in which a transparent conductive layer of (indium oxide) vapor deposited film is provided, and a CGL (charge generation layer) and CTL (charge transport layer) are laminated as photoconductive layers.

The photosensitive film 21 is generally fed in the direction of arrow E by the rotation of the film drive roller 22.

23 is a magnetic brush developing device, and a magnet roller 23a provided inside a sleeve 23b is freely rotatable. A strip-shaped recording electrode 25 made of copper foil insulated with a solid iron film is attached to the surface of the sleeve 23b.

The magnetic brush developing device 23 is filled with a developer 28 which is a mixture of a conductive carrier and an insulating toner, and the developer 28 is conveyed in the direction of the arrow in the figure by the rotation of the magnet roller 23. And 24 is developer 28
It is a gathering of people.

One voltage from a power source 26 is applied to the recording electrode 25, and ten voltages from a power source 27 are applied to the sleeve 23b.

An image exposure means 29 is arranged at a position facing the magnetic brush developing device 23 with the photosensitive film 21 interposed therebetween.

This image exposure means 29 is an L
It consists of an ED array, a cell phone lens array that condenses the image light of the LED array, and a glass plate that fixes the photosensitive film 21 so that the focal position of the image light does not shift.

30 is a toner image formed on the photosensitive film 2l, 3 is paper as described above, 4 is a transfer roller, which is made of conductive rubber, and is supplied with a voltage (+2 (10
V~+600 V) is applied.

As explained in FIG. 2, the transfer roller 4 moves in the direction of the arrow A-B, and when transferring the toner image formed on the photosensitive film 21 to the paper 3, moves in the direction of the arrow A. The cover 3 and the photosensitive film 21 are pressed onto the film drive roller 22.

At this time, the compression pressure is gradually increased, or the pressure is increased stepwise.

A toner image 34 is electrostatically transferred to the cover 3, and is fixed on the cover 3 by a heat roller fixing device 35 to become a semi-permanent recorded image 36. 37 is a residual toner image remaining on the photosensitive film 21 after the transfer.

Reference numeral 38 denotes a charge eliminating light source that removes the charge on the residual toner image 37 and the latent image charge in the photoconductive layer of the photosensitive film 2l. or,
39 is a toner image which has been neutralized and has lost its electrostatic binding force.

Next, the image recording procedure will be explained.

The photosensitive film 21 is generally fed once in the direction of the arrow E, and the magnet roller 23a of the magnetic brush developing device 23 is rotated to generally feed the developer 28 once in the direction of the arrow to create a pool of the developer 28 and record. With voltage applied to the electrode 25 and the sleeve 23b, the image exposure means 29 exposes the photosensitive film 21 to an image.

Then, photocarriers are generated in the photosensitive film 21,
The holes move toward the surface of the photosensitive film 21 and become latent image charges. Therefore, since the capacitance of the photoconductive layer apparently increases in the exposed area, the amount of adhering toner increases, resulting in a toner image with a certain degree of contrast between the exposed area and the non-exposed area.

In the area 24 where the developer 28 accumulates, the sleeve 23b
A voltage of 100 volts from a power source 27 is applied to the magnetic brush developer 23, and excess toner in the non-exposed area is collected into the magnetic brush developing device 23 by electrostatic force.

At this time, a small amount of the toner image in the exposed area is also collected, but most of the toner remains on the photosensitive film 21 and the toner image 30
is formed.

The toner image 30 is electrostatically transferred onto the cover 3 by the transfer roller 4. In electrostatic transfer using the transfer roller 4, pressing pressure is applied to the transfer roller 4 by an electromagnetic solenoid when the tip of the transfer roller 3 reaches the transfer position.

In this case, as explained in Fig. 2, when the transfer starts, the pressure is applied with a weak pressure, but by gradually increasing the current flowing through the electromagnetic solenoid or increasing it stepwise, the transfer pressure can be gradually increased. It is controlled as follows.

The transferred toner image 34 is fixed on the paper 3 by a heat roller fixing device 35, and becomes a semi-permanent recorded image 36.

On the other hand, the residual toner image 37 remaining on the photosensitive film 21 after the transfer is neutralized by the static eliminating light source 38, and the magnetic force of the magnetic brush developing device 23 scrapes off the developer 28 and the sleeve 23b
is recovered and reused by the electrostatic force caused by the applied voltage.

In this way, the collection of the residual toner image 39 and the formation of the next image can be performed simultaneously because the image exposure means 29 and the magnetic brush developing device 23 are located in opposing positions with the photosensitive film 21 in between. There are no problems.

The difference between FIG. 6(b) and FIG. 6(a) is that conductive rubber rollers 40 and 41 are provided in place of the transfer roller 4, and a conductive rubber belt 42 is rotated around these rollers. It is something.

Then, the conductive rubber roller 41 is moved in the direction of arrow A-8 using the conductive rubber roller 40 as a fulcrum shaft, and the paper 3 and the photosensitive film 21 are pressed against the film drive roller 22 via the conductive rubber belt 42. It is.

When the transfer is to be performed, a weak pressure is applied, and the pressure is gradually or stepwise increased.

〔Effect of the invention〕

As explained above, in the present invention, when the transfer of a toner image is started, the pressure with which the transfer roller presses the photoreceptor is weakened, and the pressure is gradually or stepwise increased. The transfer roller does not collide strongly with the
Mechanical deterioration and damage to the photoreceptor can be prevented, and since the transfer roller does not hound, it is also possible to prevent transfer failure.

[Brief explanation of drawings]

Fig. 1 is a block diagram explaining the principle of the present invention, Fig. 2 is a block diagram of a circuit showing an embodiment of the invention, Fig. 3 is a diagram explaining the operation of Fig. 2, and Fig. 4 is a conventional FIG. 5 is a block diagram illustrating an example of the technique, FIG. 5 is a diagram illustrating the operation of FIG. 4, and FIG. 6 is a diagram illustrating an image recording apparatus to which the present invention is applied. In the figure, 1 is a photosensitive drum, 2, 30, 34, 39 are toner images, 3 is paper, 4 is a transfer roller, 5
．． 26, 27.33 is the power supply, 6 is the fulcrum shaft, 7 is the support, 8 is the power source, 9.19 is the control circuit,
10 is a pressure control means, 11 is an image carrier, l
2 is a printing medium, 13 is a pressure bonding means, 14 is a drive means, 15 is a control means, 16 is an integrating circuit, 17 is a transistor, 18 is an electromagnetic solenoid, 20 is a switching circuit, 2l is a photosensitive film, 22 is a film drive roller, 23 is a magnetic brush developing device, 25 is a recording electrode, 28 is a developer, 29 is an image exposure means, 35 is a heat roller fixing device, 36 is a recorded image, 37 is a residual toner image, 3
8 is a static eliminating light source, 40, 41 is a conductive rubber roller, and 42 is a conductive rubber belt. ■ ■ (α冫8-!Il!fl (人冫■ ■ CC) Haruma (d) 2nd leap φη I FZ words vLaS Zrow A number 3 typos ke zto yo f') Jutosaku 1st Figure 5

Claims (1)

[Claims] When transferring a toner image (2) developed by attaching toner to a latent image formed on an image carrier (11) to a printing medium (12), the printing medium (12) is transferred to the image carrier (11). 11) A crimping means (13) to be crimped onto the crimping means (13);
and a control means (15) for instructing the drive means (14) to drive. In the transfer device, pressure control means (10) is provided for controlling the drive means (14) to increase the pressing pressure of the pressure bonding means (13) based on a drive instruction sent by the control means (15). , when starting the transfer of the toner image (2), the pressure bonding means (13) presses the printing medium (
12) is pressed against the image carrier (11), and then the pressing pressure is increased.