JPH03164756A - Electrophotographic printer - Google Patents

Abstract

PURPOSE:To improve the performance of a device to miniaturize the device and to reduce a cost by constituting a paper carrying path between a paper feeding hopper and a fixing device of a photosensitive body having a flat part, and driving a sheet only by means of the flat part of the photosensitive body. CONSTITUTION:The electrophotographic printer is provided with the paper feeding hopper 1, a mean picking up the sheet 2 from the paper feeding hopper 1, the photosensitive body 3 holding a toner image 5, a transferring unit 4 trans ferring the toner image 5 on the sheet 2, a carrying means having the carrying path of the sheet 2, and the fixing part 11 including a heat roll 8 and fixing the toner image 5 transferred on the sheet 2. The sheet carrying path between the paper feeding hopper 1 and the fixing part 11 is composed of the photosensi tive body 3, and the sheet 2 is driven only by the photosensitive body 3. Thus, the blurring in a transfer is prevented and the performance of the device is improved. A photosensitive body is used for carrying a sheet surving also as the sucking of the sheet for a transferring unit, so that a device is miniaturized and cost-down is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electrophotographic printing apparatus of a type in which paper is transferred by contacting a photoreceptor in a part of its conveyance path [Prior art] This will be explained with reference to the figures. In this electrophotographic printing device, paper 2 picked up from paper feed hopper 1
The toner image 5 held on the drum-shaped photoreceptor 3A is transferred to the paper 2 by a transfer device 4, and the fixing unit 11 consisting of a heat roll 8 and the like is transferred by a conveyor belt 6 that is sucked by a fan 7. In the case of double-sided printing, in which the paper 2 is fed into the stacker 12 and stacked in the stacker 12, the paper 2 that has passed through the fixing unit 11 is reversed by the paper reversing mechanism 1o, passes through the paper return path 13, and is fixed again. conduct.

[Problem to be solved by the invention]

Generally, such techniques have the following drawbacks.

That is, for example, in the case of paper 2 having high bending rigidity, such as cardboard, the drum-shaped photoreceptor 3A
The transfer of the toner image 5 to the paper 2 was insufficient because the close contact with the paper 2 was impaired. Furthermore, the contact area between the RIc 2 and the drum-shaped photoreceptor 3A is small, and the force with which the paper 2 is attracted to the drum-shaped photoreceptor 3A by electrostatic force is relatively small.
For example, an A3 size paper 2 is conveyed vertically and heated to the heat roll 8.
8. Problems such as blurring of the image occur at the transfer section the moment the leading edge of the paper 2 arrives. In the case of double-sided printing, similar problems occur due to deformation (curling, etc.) of the paper 2 by the heat roll 8. Further, it was difficult to completely match the speed of the drum-shaped photoreceptor 3A and the conveyance speed of the paper 2, making it impossible to perform high-precision printing. To avoid such problems,
A roller transfer method has been announced, but this method requires a roller cleaning device, which causes other problems such as an increase in the size and cost of the device.

An object of the present invention is to provide an electrophotographic printing apparatus that can improve the performance of this type of printing apparatus, reduce the size of the apparatus, and reduce costs.

[Means to solve the problem]

In order to achieve the above object, the electrophotographic printing apparatus of the present invention includes: 1. a paper feed hopper, a means for picking up paper from the paper feed hopper, a photoreceptor holding a toner image, and a photoreceptor that carries the toner image onto the paper. In an electrophotographic printing apparatus, the electrophotographic printing apparatus includes a transfer device that transfers the toner image to the paper, a conveyance means that has a short conveyance path for the paper, and a fixing section that includes a heat roll and fixes the toner image transferred to the paper. The paper transport path between the paper transport section and the paper transport section is configured by a photoreceptor, and the paper is driven only by the photoreceptor.

In 2.1, the photoconductor has an endless ring shape, is rotatable by at least one drive pulley and at least one idler pulley, and is supported so as to partially form a flat part, and the photoreceptor The present invention is characterized in that at least one support roll is provided on a flat surface between the idler pulley and a transfer device is provided opposite to the support roll.

In 3.2, the drive pulley is disposed on the heat roll side, the idler pulley is disposed on the paper feed hopper side, and the developing device is disposed on the circumference where the photoreceptor and the idler pulley are engaged. It is characterized by being arranged.

4.3, characterized in that the distance between the support roll and the transfer device is maintained constant, and the transfer device is linked to the movement of the support roll.

[Effect]

The present invention takes advantage of the fact that paper has the following effects by using a photoreceptor as a part of the paper transport section. Namely.

(1) The paper should be attracted to the photoreceptor in a 11%1i manner.

(2) The contact area between the arc-shaped photoreceptor and the almost linear paper is relatively small and the suction force is weak.

(3) The bending rigidity of the trailing edge of the paper that is attracted to the drum-shaped photoreceptor around the transfer point is compared to the cube of the attraction length, and the rear end of the paper overcomes the attraction force of the photoreceptor. Compared to this, if the paper is adsorbed to a flat photoreceptor, the adsorption force of the paper is strong and the trailing edge of the paper does not come off.

(4) If the paper is conveyed during transfer using only the photoreceptor, no blurring will occur at the transfer section.

By doing so, it is possible to reduce the size and cost of the device.

〔Example〕

An embodiment of the present invention will be described based on FIG. Reference numeral 3 denotes an endless belt-shaped photoreceptor, which is disposed approximately horizontally between the paper feed hopper 1 and the heat roll 8, and is supported by a drive pulley 15 and an idler pulley 16. A paper 2 is picked up from a paper feed hopper 1, conveyed to a paper conveyance path, and is attracted to a belt-shaped photoreceptor 3. Belt-shaped photoreceptor 3
Around the belt-shaped photoreceptor 3 are a charger 19 that charges the belt-shaped photoreceptor 3 to a predetermined potential, a laser diode 20 that records an electrostatic latent image on the belt-shaped photoreceptor 3 based on a print signal, and a developing device 14.
are arranged respectively. Therefore, the paper 2 is electrostatically attracted to the charged belt-like photoreceptor 3.

The paper 2 attracted to the belt-like photoreceptor 3 is conveyed by the belt-like photoreceptor 3 driven by the drive pulley 15, and the toner image 5 on the belt-like photoreceptor 3 is transferred to the paper 2 by the transfer device 4, and then heated. In the case of double-sided printing in which paper 2 is fixed by roll 8 and pressure roll 9 and stacked by stacker 12, after fixing, paper 2 is reversed by paper reversing mechanism 10, passed through paper conveyance path 13, and then stacked again. , transfer, fix, and stack. Approximately in the center of the belt-shaped photoreceptor 3 is a support roll 1 that can rotate once.
7 from the inside with a spring 18, this support roll 17
A transfer device 4 is disposed opposite to.

Near the transfer point, the paper 2 and the belt-shaped photoreceptor 3 are electrostatically attracted to each other over a wide area. 3 has a strong adsorption force, and even when the paper 2 is moved by the thermal roll 8, transfer blur does not occur, and the paper 2 is deformed by heat absorption and heat fixation, so that the paper 2 is exposed to a belt-like photosensitive material at the transfer point. It does not peel off from the body 3 and cause transfer defects. Since the paper 2 and the belt-shaped photoreceptor 3 are attracted to each other in a flat, planar manner, the paper 2 does not peel off from the belt-shaped photoreceptor 3 at the leading and trailing ends of the paper 2 due to its bending rigidity. . The belt-shaped photoreceptor 3 is attached to a drive pulley 15 on the heat roll 8 side.
I am driving.

At the point where the paper 2 starts to be attracted to the belt-like photoreceptor 3, the belt-like photoreceptor 3 is stretched, and there is little variation in the point at which the paper 2 starts to be attracted to the belt-like photoreceptor 3. The developing device 14 is disposed around the outer periphery of the idler pulley 16 so that the developing gap does not fluctuate. Further, the support roll 17 and the transfer device 4 are connected by a mechanism not shown, and the distance between the support roll 17 and the transfer device 4 is set to be constant. Therefore, even if the support roll 17 moves up and down a little, the distance between the paper 2 attracted to the belt-shaped photoreceptor 3 and the transfer device 4 does not change.

The present invention can also be modified as follows. That is, (1) A roller for guiding the paper 2 facing the belt-like photoreceptor 3 may be provided to sandwich the paper 2 between the belt-like photoreceptor 3 and the roller.

(2) The paper 2 may be transported above the belt-shaped photoreceptor 3.

(3) A plurality of developing machines 14 may be provided to perform multicolor printing.

〔Effect of the invention〕

According to the present invention, the paper conveyance path between the paper feed hopper and the fixing unit is configured with a photoreceptor having a flat part, and the paper is driven only by the flat part of the photoreceptor. Transfer blur caused by misalignment with the paper or paper rigidity can be prevented, and the photoconductor also serves as paper transport and transfer device paper suction, making installation more compact and reducing costs. Furthermore, when paper is repeatedly conveyed two or more times during multicolor printing, the adsorption and holding force between the paper and the photoreceptor is strong and color misregistration does not occur.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an electrophotographic printing apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional electrophotographic printing apparatus.

Claims (1)

[Scope of Claims] 1. A paper feed hopper, a means for picking up paper from the paper feed hopper, a photoreceptor holding a toner image, a transfer device for transferring the toner image onto the paper, and a transfer device for transferring the toner image onto the paper; In an electrophotographic printing apparatus including a conveyance means having a conveyance path, and a fixing section for the toner image transferred to the paper sheet including a heat roll, the paper conveyance path between the paper feed hopper and the fixing section is provided. An electrophotographic printing apparatus comprising a photoreceptor and driving the paper only by the photoreceptor. 2. In claim 1, the photoreceptor has an endless ring shape, is rotatable by at least one drive pulley and at least one idler pulley, and is supported so as to partially form a flat part, and the drive pulley and the idler pulley, at least one support roll is provided on a flat surface, and a transfer device is provided opposite to the support roll. 3. In claim 2, the drive pulley is disposed on the heat roll side, the idler pulley is disposed on the paper feed hopper side, and the developing device is disposed on the circumference where the photoreceptor and the idler pulley are engaged. An electrophotographic printing device placed on top. 4. The electrophotographic printing apparatus according to claim 3, wherein a distance between the support roll and the transfer device is maintained constant, and the transfer device is linked to the movement of the support roll.