JPS6296983A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a proper extent of pressuring by providing a means which controls the extent of abutting of a rotating body and an encoder which detects the position of the rotating body. CONSTITUTION:When a transfer sheet 25 passes between a dielectric drum 1 and a transfer and fixing roll 2, the transfer and fixing roll 2 is moved down by an extent corresponding to the thickness of the transfer sheet 25, and a pulse is outputted from an encoder 23. A sequence control part 31 reads in the number of pulses to calculate a pressuring force during sheet passage and compares it with a proper value from a table set in an internal ROM, and pressuring is continued until it reaches the proper value if they do not coincide with each other. When it reaches the proper value, a brake 17 is put on and a pressuring motor 19 is turned off to fix the transfer and fixing roll 2, and when sheet passage is terminated, the brake 17 is put off to release pressuring. Thus, a proper extent of pressuring is always obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to image forming apparatuses such as copying machines, laser beam printers, and low electrostatic recording devices thereof, and particularly relates to image forming apparatuses such as copying machines, laser beam printers, and low electrostatic recording devices thereof, and in particular to W4 images formed on image carriers. The present invention relates to an image forming apparatus that pressure-transfers images onto a transfer material.

(Prior art) Recently, devices such as copiers and laser beam printers have come to be used as part of systems such as computer output devices, and these devices are required to be even faster and more reliable. . In order to meet this demand, developing,
In place of conventional devices that require each step of transfer and fixing, this system forms an electrostatic latent image on the surface of a dielectric drum in accordance with an image signal, and then visualizes the electrostatic latent image using a toner developer. The toner image is transferred from the surface of the dielectric drum onto the transfer material by passing the transfer material through the pressure contact area between the dielectric drum and the transfer fixing roller that rotates in pressure contact with the dielectric drum. A device for pressure-setting a toner image is known from Japanese Patent Application Laid-Open No. 78134/1983.

According to this device, after the toner image is transferred from the surface of the dielectric drum onto the transfer material, there is no need to use a heat roller fixing device or the like in the next step to fix it, making the device more compact and eliminating the need for a fixing device. At the same time, the conveyance path of the transfer material can be made shorter than that of the conventional method. This has the extremely large effect of making it difficult for transfer material conveyance defects to occur and improving reliability.

Conventionally, drive control of a transfer fixing roller that is in pressure contact with a dielectric drum has been performed as follows. That is, a pressure motor and a pressure brake are used to detect the positions when the transfer fixing roller is in pressure contact with the dielectric drum and when it is separated from the dielectric drum using microswitches, and drive the transfer fixing roller in the direction of contacting and separating from the dielectric drum. was under 0N10FF control.

(Problems to be Solved by the Invention) However, in the case of such prior art, since the positioning of the transfer and fixing roller during pressurization is simply performed by a microswitch, problems such as abnormalities in the contacts of the microswitch may occur. If the operating position of the microswitch changes due to loosening of the spring, etc., phenomena such as too much pressure or not enough pressure may occur during operation.

If such a situation occurs, the transfer and fixation will be incomplete, resulting in not only a deterioration in transfer efficiency but also a residual toner pressurized after transfer and fixation remaining on the dielectric drum, making cleaning difficult.

In addition, when operating for a long time with too much pressure applied, it has a large effect on other mechanisms, and the high pressure actually applied can cause equipment damage.

Furthermore, since the amount of pressure is set only by detecting the upper limit position of the transfer and fixing roller using a microswitch, only a certain amount of pressure can be applied, and if the transfer material is double fed, the dielectric drum This has the problem of not being able to respond flexibly to changes in the thickness of the transfer material being passed through, such as the large impact that is given to the device when it enters between the transfer material and the transfer fixing roller.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to be able to accurately detect the position of a rotating body such as a transfer fixing roller with a simple configuration. An object of the present invention is to provide an image forming apparatus that can obtain an appropriate amount of pressurization.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms a latent image on the surface of an image carrier according to an image information signal and visualizes the latent image. In an image forming apparatus, the developed image is pressure-transferred onto a transfer material by the contact pressure of a rotary body that rotates in pressure contact with the image forming apparatus, and means for adjusting the amount of pressure of the rotary body; An encoder is provided to detect the position of the rotating body, and the contact pressure is controlled by detecting the position of the rotating body using the encoder.

(Example) The present invention will be explained below based on the illustrated example. 1st
In the figure, l is a dielectric drum serving as an image carrier, and around the dielectric drum 1, as shown in FIG. A recording head IO1, a developing device 102 for making the latent image visible, a cleaning device 103, and a static eliminator 104 are provided. Reference numeral 2 denotes a transfer fixing roller which rotates while being in pressure contact with the dielectric drum 1, and the transfer fixing roller 2 is connected to a first arm 3,
The first arm 3.4 is rotatably supported on the first arm 3.4.
is capable of swinging around a fulcrum 5.6. Further, the swinging end of the first arm 3.4 is connected to the second arm via the spring 7.
It is connected to one end of arms 8 and 9. This second arm 8.9 is pivotable about a shaft 10.11 located approximately at the center, and the other end of the second arm 8.9 has a
A disc 12.13, whose four ends are in contact with rollers 14 provided on the eccentric portion of the disc 12, 13 so as to be able to push down, is fixed to both ends of the support shaft 15, and the disc of the support shaft 15 A pressure gear 16 is fixed to the 13 side. This pressure gear 16 is meshed with a control gear 18 fixed to a brake shaft of an electric brake 17, and furthermore, the control gear 18 is meshed with a drive gear 20 fixed to a drive shaft of a pressure motor 19. ing.

Further, a rack 21 is provided on the non-rotating axis of the transfer fixing roller 2 and extends toward the anti-dielectric drum 1.
A gear 22 is meshed with the rack 21. An encoder 23 is coaxially fixed to this gear 22.

FIG. 2 is a schematic diagram of a paper feeding section in this apparatus, in which a transfer material (hereinafter simply referred to as a transfer sheet) 25 stored in a paper feeding cassette 24 is fed by a paper feeding roller 26 and then moved to a registration roller 29. transported to. This registration roller 29 feeds the transfer sheet 25 to the pressure contact portion between the dielectric drum 1 and the transfer fixing roller 2 at a predetermined timing.

FIG. 3 is a block diagram showing the control system. Reference numeral 30 is a key manual section provided on the operation panel for inputting data on the size, thickness and number of transfer materials; 31 is a sequence control section; 32
is the pressurizing motor 1 according to the signal from the sequence control section.
9 and a driver that drives the brake 17, 33 is an SSR
It is.

In the above configuration, in the image forming apparatus according to the present invention,
The pressing force between the dielectric drum and the transfer and fixing roller is controlled in the following manner. That is, after an electrostatic latent image is formed on the surface of the dielectric drum 1 in accordance with an image signal, the electrostatic "rW, WJ" image is visualized by a developing device to form a toner image.

In synchronization with this toner image formation on the dielectric drum l, the sequence control section 31 performs sequence control according to the flowchart shown in FIG. First, the key manual section 30 selects the paper thickness, sets the number of sheets, and sets the paper size.
Operate the start button. Therefore, the sequence control unit 31 calculates the amount of pressure corresponding to the input paper thickness data in advance from a table in an internal ROM (not shown), and
The pressurizing motor 19 is driven. That is, the pressure motor 19
When the gear 18.16 rotates, the gear 18.16 meshes with the drive gear 20.
The rotation of the support shaft 15 causes the rollers 14 to push down one end of the second arm 8.9. Then, the swinging ends of the first arms 3 and 4 are pushed up via the spring 7, and the transfer and fixing roller 2 moves upward and comes into pressure contact with the dielectric drum 1. As the transfer fixing roller 2 moves upward, the gear 22 attached to the center of the transfer fixing roller 2 also moves upward, and the gear 22 meshing with the rack 21 rotates. Encoder 2 corresponding to the amount of rotation of this gear 22
By counting the pulse output from 3, the sequence control unit 31 detects the amount of upward movement of the transfer fixing roller 2, and when a predetermined output pulse is counted, the sequence control unit 31 stops power supply to the pressure motor 19. , supplies power to the electric brake 17, and restricts rotation of the control gear 18 by the action of the brake 170.

As a result, the dielectric drum 1 and the transfer/fixing roller 2 are held in contact with each other by a predetermined pressure. Here, the registration roller 29 rotates, and the transfer sheet 25 is transferred to the dielectric drum 1.
In synchronization with the upper toner image, the toner image is fed into the pressure contact portion between the dielectric drum 1 and the transfer fixing roller 2, and pressure transfer and pressure fixing are performed at the same time. Although this embodiment shows an example in which fixing is performed simultaneously with pressure transfer, the present invention is not limited to this. Only pressure transfer is performed using the dielectric drum and roller, and the fixing process is performed after the transfer process is completed. You can do it like this.

Next, the sequence control unit 31 executes pressure control during paper passing as follows. When the transfer sheet 25 passes between the dielectric drum 1 and the transfer fixing roller 2, the transfer fixing roller 2 moves downward by the thickness of the transfer sheet 25, and is thereby attached to the non-rotating shaft of the transfer fixing roller 2. The rotated gear 22 also moves downward. Therefore, rack 21
The gear 22 meshed with the encoder 23 rotates, and the encoder 23 outputs pulses. The sequence control unit 31 reads this number of pulses, calculates the pressing force during paper passing, and stores it in the internal ROM.
(not shown). If it does not match this appropriate value, the brake 17 is turned off via the driver 32 and the pressurizing motor 19 is turned off.
ONL and then continue applying pressure for 1n until the appropriate value is reached.

When the proper value is reached, the transfer fixing roller 2 is fixed by turning on the brake 17 and turning off the pressure motor 19.

At the time when paper passing is completed, the brake 17 is released from the pressure of 0FFL.

In the above embodiment, the encoder 23 is provided only at one end of the transfer fixing roller 2, but encoders may be provided at both ends of the transfer fixing roller, and in such a case, the pressure contact force of the transfer fixing roller is reduced. Detection can be performed more accurately and more uniform pressure contact force can be obtained.

Further, in the above-mentioned embodiments, a case has been described in which a dielectric drum is used as an image carrier, but the present invention can also use a photosensitive drum as an image carrier. In this case, the photosensitive drum is subjected to well-known uniform charging and photoimage exposure to form a latent image.

(Effects of the Invention) The present invention has the above-described configuration and operation, and the encoder detects the position of the rotating body that rotates in pressure contact with the image carrier and controls the contact pressure. The position can be detected with high precision with a simple configuration, and an appropriate amount of pressurization can always be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a schematic diagram showing a conveyance system for a rotating transfer sheet, and FIG. 3 is a block diagram showing a control system. FIG. 4 is a flowchart showing a program executed by the control system. Explanation of symbols 1...Dielectric drum 2...Transfer and fixing roller 1
7... Electric brake 19... Pressure motor 21.
... Rack 22 ... Gear 23 ... Encoder 31 ... Sequence control section Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] A latent image corresponding to the image information signal is formed on the surface of the image carrier, and this is visualized, and the developed image is transferred onto the transfer material by the contact pressure between the image carrier and a rotating body that presses against the image carrier and rotates. The image forming apparatus is configured to perform pressure transfer on the rotary body, and is provided with means for adjusting the amount of pressure contact of the rotary body and an encoder for detecting the position of the rotary body, and the encoder detects the position of the rotary body and transfers the pressure to the rotary body. An image forming apparatus characterized by controlling contact pressure.