JPH04340570A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an image forming apparatus that visualizes an electrostatic latent image formed on a photoreceptor using toner, transfers it to paper, and fixes it using heat or pressure. .

0002

2. Description of the Related Art Until now, most image forming apparatuses have been devices that use dry toner, and have been put into practical use as many copying machines, laser printers, and the like, and have made remarkable progress. This image forming apparatus is a device that applies electrophotographic process technology, and visualizes an electrostatic latent image formed on a photoreceptor having a photosensitive layer using toner particles.

Image forming apparatuses employing a one-component development method that uses only toner as a developer generally include a toner thin layer section that frictionally charges the toner to form a thin layer on the developing roller, and a toner hopper that stores the toner. It has a department.

The toner in the toner hopper is conveyed to the developing roller by the replenishment roller, and is charged by the frictional force between the developing roller and the doctor blade, forming a thin layer on the developing roller.

A portion of the thin layer of toner on the developing roller is used to visualize the electrostatic latent image formed on the photoreceptor, and the remaining unused toner is transferred between the Mylar sheet and the developing roller. It passes through and is returned to the hopper section.

However, at this time, toner accumulation may occur due to unused toner that cannot pass between the Mylar sheet and the developing roller. When such toner accumulation occurs, toner scattering occurs, causing dirt and grime inside the machine. This results in deterioration of the output image. Therefore, conventionally, various measures have been taken to eliminate this accumulated toner and prevent toner scattering.

A conventional image forming apparatus will be explained below. FIG. 3 is a schematic sectional view of a conventional image forming apparatus, and FIG. 4 is an enlarged sectional view of main parts of the conventional image forming apparatus. In the figure, reference numeral 1 denotes a photoreceptor having a drum made of aluminum or the like as a base material, and a photosensitive receiving layer such as selenium (Se) or organic photoconductor (OPC) coated in a thin layer on the outer peripheral surface of the drum. This photoreceptor 1
is rotated in the direction of arrow A by a drive motor (not shown).

A charger 2, a developer 3, a transfer device 12, a cleaning device 13, and a static eliminator 15 are provided on the circumferential surface of the photoreceptor 1 in the rotational direction indicated by an arrow A. Charger 2
is composed of a charging wire 2a made of tungsten wire or the like, a shield plate 2b made of a metal plate, and a grid plate 2c. By applying a high voltage to the charged wire 2a, the charged wire 2a causes corona discharge, and the grid plate 2c
The photoreceptor 1 is uniformly charged through.

B is a laser beam of image data emitted from the exposure optical system 18. In the case of a laser printer, this laser light B is controlled by a signal from a host computer (not shown) and forms an electrostatic latent image on the photoreceptor 1.

Reference numeral 7 denotes a toner conveying member, which is made of a wire made of stainless steel or the like, and its both ends are rotatably supported by both ends of the developing vat 3a. The toner conveying member 7 prevents the toner 6 in the developing device 3 from blocking and conveys the toner 6 onto the replenishment roller 5 .

The replenishing roller 5 is rotatably supported at both ends by the developing vat 3a, and replenishes the surface of the developing roller 4 with the toner 6 conveyed by the toner conveying member 7, and is made of metal such as stainless steel. A conductive layer of urethane or the like is formed on the outer peripheral surface of the base material.

The developing roller 4 is made of a metal such as stainless steel, and has a conductive layer of silicon, urethane, etc. formed on its outer peripheral surface. The developing roller 4 is rotatably supported at both ends of the developing vat 3a. The toner 6 replenished by the replenishment roller 5 is charged by a doctor blade 9 made of a conductive material such as silicone or urethane, and forms a thin layer on the outer periphery of the developing roller 4, and comes into contact with the photoreceptor 1. Then, toner 6 is applied to the portion of the photoreceptor 1 where the electrostatic latent image is formed, thereby forming a toner image.

The doctor blade 9 is attached to the upper part of the developing device 3 by an attachment member 8 so that its tip comes into contact with the developing roller 4.

Reference numeral 16 denotes a Mylar sheet made of a film such as PET, which prevents the toner 6 in the developing device 3 from flowing out of the developing device 3.

Reference numeral 19 denotes a copy paper cassette in which copy paper 11 is stored. Copy paper 11 is fed one by one from a copy paper cassette 19 to conveyance roller 10 by a half-moon-shaped paper feed roller 20. Reference numeral 21 denotes a registration roller for temporarily stopping and waiting the copy paper 11 in order to align the positions of the copy paper 11 and the toner image formed on the photoreceptor 1, and is in pressure contact with the driven roller 22. The transfer device 12 includes a transfer line 12a made of tungsten wire or the like and a shield plate 12b made of a metal plate.

When a high voltage is applied to the transfer line 12a, the transfer line 12a generates corona discharge, and the toner image on the photoreceptor 1 is transferred onto the copy paper 11. A fixing device 23 is composed of a heat roller 24 having an internal heat source and a pressure roller 25, and the toner image transferred onto the copy paper 11 is fixed by the pressure caused by the rotation of the heat roller 24 and the pressure roller 25. It is fixed on the copy paper 11 by heat.

The operation of the electrophotographic apparatus configured as described above will be explained below.

First, a high voltage is applied to the charging wire 2a in the charger 2 connected to a high voltage power source to cause corona discharge, and the surface of the photoreceptor 1 is uniformly charged to about -700V to -800V. Next, the photoconductor 1 is rotated in the direction of the arrow A, and the uniformly charged surface of the photoconductor 1 is irradiated with laser light B, thereby discharging the portion irradiated with the laser beam B, and the surface of the photoconductor 1 is forms an electrostatic latent image.

On the other hand, the toner 6 stored in the developing device 3 is conveyed onto the supply roller 5 by a rotating toner conveying member 7 driven by a connecting gear (not shown) connected to the developing roller 4. Ru.

The toner 6 conveyed onto the supply roller 5 is
The toner is replenished onto the surface of the developing roller 4 to form a toner layer on the surface of the developing roller 4 . The toner layer formed on the developing roller 4 is transferred to the doctor blade 9 while rotating in the direction of the arrow.
is charged, forms a thin layer, and is conveyed to a contact position with the photoreceptor 1.

When a potential difference is applied between the developing roller 4 and the photoreceptor 1 at this contact position, the toner 6 adheres to the electrostatic latent image portion formed on the photoreceptor 1, forming a toner image, and the developing ends. The toner 6 on the developing roller 4 that did not contribute to development passes between the Mylar sheet 16 and the developing roller 4 in a thin layer state, is scraped off by the supply roller 5, and returned to the developing vat 3a.

The toner image thus formed is transferred onto the copy paper 11 fed from the copy paper cassette 19 by applying high voltage to the transfer line 12a in the transfer device 12 to cause corona discharge. The image is then transferred to the fixing device 23 and fixed by the heat of the heat roller 24 and the clamping pressure of the pressure roller 25, and output as an image.

[0023]

However, in the above-mentioned conventional device, the contact area between the developing roller 4 and the Mylar sheet 16 is very small, almost a line contact state, and the sealing force of the toner in the developing unit is insufficient. Therefore, there was a problem in that the toner inside the developing device was scattered out of the developing device from between the developing roller 4 and the Mylar sheet 16 due to a slight external impact or the like, resulting in image deterioration.

Therefore, an object of the present invention is to provide an image forming apparatus that can solve the above problems.

[0025]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a developing device that attaches toner to an electrostatic latent image formed on a photoconductor to visualize it, and a developing device that makes an electrostatic latent image formed on a photoreceptor. An image forming apparatus comprising: a doctor blade that applies toner to a uniform layer thickness on a developing roller and charges the toner; and a Mylar sheet provided between the developing roller and a developing bat of a developing device. By disposing an elastic member on the back surface of the Mylar sheet, the Mylar sheet is pressed against the developing roller.

[0026]

[Operation] According to the above structure, due to the elastic force of the elastic member,
Place the Mylar sheet in firm surface contact with the developing roller.
Since sufficient sealing force can be ensured, it is possible to reliably prevent toner scattering due to external impact or the like.

[0027]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to the present invention, and FIG. 2 is an enlarged cross-sectional view of essential parts of the image forming apparatus according to the present invention. Here, the same components as those of the conventional image forming apparatus described above are given the same reference numerals, and detailed description thereof will be omitted.

In FIG. 2, one end 16a of the Mylar sheet 16 is adhered to the end 3d of the developing vat 3a located below the developing roller 4 with an adhesive member 16c such as double-sided tape. Reference numeral 26 denotes an elastic member formed into a sheet shape from urethane foam or the like, and is disposed on the back surface of the Mylar sheet 16. Therefore, the Mylar sheet 16 is firmly pressed against the developing roller 4 due to the elastic force of the elastic member 16, and is in surface contact with the developing roller 4, ensuring sufficient sealing force between the Mylar sheet 16 and the developing roller 4, and allowing the toner to be removed from the gap between the two. can be prevented from scattering.

In the above configuration, first, a high voltage is applied to the charging wire 2a in the charger 2 connected to a high voltage power source to cause corona discharge, and the surface of the photoreceptor 1 is uniformly heated to -700V to -700V.
It is charged to about -800V. Next, the photoconductor 1 is rotated in the direction of arrow A, and the uniformly charged surface of the photoconductor 1 is irradiated with laser light B, thereby discharging the portion irradiated with the laser beam B, and causing the surface of the photoconductor 1 to be discharged. Forms an electrostatic latent image.

On the other hand, the toner 6 stored in the developing device 3 is conveyed onto the replenishment roller 5 by the toner conveying member 7.

The toner 6 conveyed onto the supply roller 5 is
The toner is replenished onto the surface of the developing roller 4 to form a toner layer on the surface of the developing roller 4 . The toner layer formed on the developing roller 4 rotates in the direction of the arrow, is charged by a doctor blade 9 to form a thin layer, and is conveyed to a contact position with the photoreceptor 1.

When a potential difference is applied between the developing roller 4 and the photoreceptor 1 at this contact position, the toner 6 adheres to the electrostatic latent image portion formed on the photoreceptor 1, forming a toner image, and the developing ends.

The toner 6 on the developing roller 4 that did not contribute to development passes between the mylar sheet 16 and the developing roller 4 in a thin layer state, is scraped off by the supply roller 5, and returned to the developing vat 3a. The toner image formed in this manner is transferred onto the copy paper 11 fed from the copy paper cassette 19 by applying high voltage to the transfer line 12a in the transfer device 12 to cause corona discharge. , followed by the heat of the heat roller 24 of the fixing device 23 and the pressure roller 2.
The image is fixed by a clamping pressure of 5 and output as an image.

[0035]

As described above, the present invention provides a developing device that attaches toner to an electrostatic latent image formed on a photoconductor to make it visible, and a developing device that forms a uniform layer on a developing roller in the developing device. This method includes a doctor blade that applies toner thickly and charges it, and a Mylar sheet that is provided between the developing roller and the developing bat of the developing device, and an elastic member is provided on the back side of the Mylar sheet. Since the mylar sheet is pressed against the developing roller, the elastic force of the elastic member brings the mylar sheet into firm surface contact with the developing roller.
Sufficient sealing force can be ensured to prevent toner from scattering between the Mylar sheet and the developing roller.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus in an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of main parts of an image forming apparatus in an embodiment of the present invention.

[Fig. 3] Schematic cross-sectional view of a conventional image forming apparatus

[Fig. 4] Enlarged cross-sectional view of main parts of a conventional image forming apparatus

[Explanation of symbols]

1 Photoreceptor 2　Charger 3 Developing device 4 Developing roller 5 Supply roller 6 Toner 9 Doctor Blade 16 Mylar sheet 26 Elastic member

Claims (1)

[Claims] 1. A developing device that applies toner to an electrostatic latent image formed on a photoconductor to visualize it; and a developing device that applies toner to a uniform layer thickness on a developing roller in the developing device to charge the electrostatic latent image. A Mylar sheet is provided between the developing roller and the developing vat of the developing unit, and an elastic member is provided on the back surface of the Mylar sheet to push the Mylar sheet against the developing roller. An image forming apparatus characterized in that the image forming apparatuses are brought into contact with each other.