JPH03140981A - Mechanism for pressing developing device - Google Patents

Abstract

PURPOSE:To prevent the generation of a difference in printing density in the axial direction of paper by constituting the above mechanism in such a manner that a developing device can oscillate around the position equidistant from both gap rollers with respect to a supporting shaft. CONSTITUTION:The developing device 3 is connected to the supporting shaft 2 via the pin 8 in the position equidistant from both gap rollers 6 and is supported in such a manner that the developing device 3 can oscillate around the axial center of the supporting shaft 2 in the directions approaching and parting to and from the photosensitive body 5. The developing device 3 is energized by a spring 4 via a lever 10, the supporting shaft 2, the pin 8 and a fitting 9 in the direction approaching to the photosensitive body 5. Even if, therefore, the supporting shaft 2 inclines with respect to the surface of the photosensitive body 5, the developing device 3 oscillates around the axial center of the pin 8 and the torque around the axial center of the pin 8 acting on both gap rollers 6 received by the surface of the photosensitive body 5 settles in the balancing position. The generation of the difference in the printing density in the transverse direction of the paper is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer pressing mechanism, and particularly to a developer pressing mechanism of an electronic printer.

3. Detailed Description of the Invention [Prior Art] In general, in electronic printers, an exposure device forms a latent image on the surface of a photoreceptor based on image information, and a developing device forms a latent image on the surface of a photoreceptor.
A latent image is developed by attaching a developer (developing agent) to the latent image, and an image is formed on the paper by electrostatically transferring the toner from the surface of the photoreceptor to the paper using a transfer device.

Conventionally, the developing device needs to face the photoreceptor at a predetermined distance, so for example, as shown in FIGS.
It is pressed against the photoreceptor 5 by the developer pressing mechanism shown in the figure.

This developing device pressing mechanism pushes a developing device 3 onto a support shaft 2 which is rotatably supported on a frame l via a metal fitting 7.
The developing device 3 is supported so as to be able to swing around its axis, and the developing device 3 is biased by a spring 4 in a direction approaching the photoreceptor 5 via the support shaft 2 and the metal fitting 7, so that both ends of the developing device 3 in the axial direction are supported. A pair of gap rollers 6 rotatably supported on the photoreceptor 5 are configured to be received by the photoreceptor 5.

[Problem to be solved by the invention]

However, according to this conventional developer pressing mechanism, both ends of the support shaft 2 are supported by the frame l, and the developer 3 is fixed to the support shaft 2 via the metal fitting 7 over its entire length in the direction of the swing axis. Therefore, if the axis of the support shaft 2 is even slightly inclined with respect to the surface of the photoreceptor 5, as shown by the imaginary line in FIG. 6 is pressed against the photoreceptor 5 (contact pressure), and the gap between the developing device 3 and the photoreceptor 5, that is, the size of the developing gap, changes slightly between the left and right sides of the developing device, and the width of the paper changes. It has been found that there is a difference in print density in the direction, that is, in the direction perpendicular to the paper feeding direction.

It has also been found that similar problems may occur due to dimensional errors in manufacturing the developing unit 3 itself, dimensional errors in assembling the gap rollers 6 and the developing unit 3, and the like, in addition to dimensional errors in the rear parts.

The present invention has been made in consideration of the above circumstances,
The purpose of this is to prevent differences in print density from occurring in the width direction of the paper by eliminating differences in the pressing pressure of the developing device against the photoreceptor.

[Means to solve the problem]

As shown in FIG. 1, for example, the present invention allows a frame 1 to swingably support a developing device 3 via a support shaft 2;
A spring 4 urges the developing device 3 in a direction toward the photoreceptor 5, and a pair of gap rollers 6 rotatably supported at both ends of the developing device 3 in the direction of the swing axis are attached to the photoreceptor 5. In order to achieve the above object in a developing device pushing mechanism of an electronic printer configured to receive the developing device, the following measures are taken.

That is, the developing device 3 is swingably connected to the support shaft 2 via a pin 8 at a position equidistant from both gap rollers 6, and the axis of the pin 8 is located at the connection point between the support shaft 2 and the developing device 3. P and the axes of both gap rollers 6,
Or make them orthogonal.

[Effect]

In the present invention, since the developing device 2 is swingably connected to the support shaft 2 via the bin 8, there is a dimensional error in the frame 1 that supports both ends of the support shaft 2, and the support shaft 2 is attached to the photoreceptor. 5
Even when the developing unit 3 is tilted with respect to the surface of the pin 8, the developing unit 3 swings around the axis of the bottle 8, and the axis of the pin 8 that acts on both gap rollers 6 received on the surface of the photoreceptor 5 is rotated. It settles at a position where the torque around it is balanced. Here, since the position of the bin 8 is set at the same distance from both gap rollers 6, the pressure acting on both gap rollers 6 is always equal.

〔Example〕

Hereinafter, a case where a developing device pressing mechanism according to an embodiment of the present invention is applied to an electronic printer will be described with reference to FIGS. 1 and 2.

The frame 1 is constructed of a temporary frame, and rotatably supports both left and right (top and bottom in FIG. 1) ends of a support shaft 2 whose axis is horizontal. A tram-shaped photoreceptor 5 is arranged parallel to the support shaft 2 diagonally below the front side of the support shaft 2 (on the upper right side of FIG. will be placed.

This developing device 3 is connected to the support shaft 2 via a metal fitting 9 and a pin 8.
By connecting the developing device 3 to the frame 1, the supporting shaft 2
The photoreceptor 5 is supported so as to be swingable about the axis in a direction toward and away from the photoreceptor 5. Further, in this developing device 3, the lever 10, the support shaft 2, the pin 8, and the metal fitting 9 are connected to each other by a spring 4 that is attached between the free end of the lever 10 fixed to one end of the support shaft 2 and the frame 1. The photoreceptor 5 is biased toward the photoreceptor 5 through the photoreceptor 5. As a result, the developing device 3
A pair of gap rollers 6 rotatably supported at both left and right ends of the front side are received by the photoreceptor 5, so that a predetermined developing gap is set between the developing device 3 and the photoreceptor 5. ing.

In order to function as a reinforcing member for the developing device 3, the metal fitting 9 is fixed over the entire length of the upper edge of the rear end of the developing device 3, and has a U-shaped shape that sandwiches the support shaft 2 from above and below at the upper center in the left-right direction. A bracket portion 9a is provided. Both gap rollers 6 are provided on the upper and lower sides of this bracket portion 9a.
A bottle hole 11 is formed equidistant from the support shaft 2.
By inserting pins 8 that pass through the bottle holes 11 in the vertical direction, the developing device 3 is aligned with respect to an inclined plane that includes the connecting point P between the support shaft 2 and the developing device 3 and the axes of both gap rollers 6. The pin 8 can be horizontally oscillated about the axis of the pin 8 which is tilted.

According to this developing device pressing mechanism, since the developing device 3 is swingably connected to the support shaft 2 via the pin 8, the support shaft 2
There is a dimensional error in the frame 1 that supports both ends of the first
As shown by the imaginary line in the figure, when the support shaft 2 is inclined in the front-rear direction with respect to the surface of the photoreceptor 5, the developing device 3 swings around the axis of the pin 8 and The torque around the axis of the pin 8 acting on both gap rollers 6 received on the surface of the body 5 settles at a position where they are balanced. here,
Since the position of the pin 8, that is, the position of the bottle hole 11, is set at the same distance from both gap rollers 6, the pressure acting on both gap rollers 6 is always equal. As a result, the development gap formed between the developer 3 and the photoreceptor 5 becomes uniform across the entire left and right direction of the developer 3, and it is possible to prevent differences in print density from occurring in the width direction of the paper. .

Here, we have explained an example in which the support shaft 2 is inclined in the front-rear direction with respect to the surface of the photoreceptor 5 due to a dimensional error in the frame I. Even if there is an error, if there is an error in the mounting position of both gap rollers 6 on the left and right sides of the developing device 2, or if two or more of these causes conflict, the pressure acting on both gap rollers 6 will always be maintained. This makes it possible to prevent differences in print density from occurring in the width direction of the paper.

In the above embodiment, the pin 8 passes through the support shaft 2, but the position of the pin 8 is not particularly limited as long as it is set at the same distance from both gap rollers 6.
The pin 8 may be set at a position away from the support shaft 2 by connecting a bracket to the bracket and fixing the pin 8 to the bracket or passing the pin 8 through the bracket.

Further, in the above embodiment, the axis of the pin 8 is directed in the vertical direction, but the direction of the axis of the pin 8 is the connecting point between the support shaft 2 and the developing device 3 by the pin 8 (in the above embodiment). In the example, it is sufficient that the plane is inclined or perpendicular to the plane including the intersection point P between the axis of the support shaft 2 and the pin 8 and the axis of both the gap rollers 6.

[Effects of the Invention] As described above, according to the present invention, since the developing unit is configured to be able to swing relative to the support shaft around a position equidistant from both gap rollers, the rear parts, Even if there is a dimensional error in the developing device or an assembly dimensional error between the developing device and each gap roller, the developing device always settles at a position where the contact pressure of both gap rollers against the photoreceptor is equal. Therefore, since the development gap between the developing device and the photoreceptor is kept strictly constant in the width direction of the paper, it is possible to prevent differences in print density from occurring in the width direction of the paper.

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[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing a developing device pressing mechanism of an electronic printer according to an embodiment of the present invention, FIG. 2 is a side view schematically showing the developing device pressing mechanism, and FIG. This figure is a plan view schematically showing a conventional electronic blink developing device pressing mechanism, and FIG. 4 is a longitudinal sectional side view schematically showing the developing device pressing mechanism. In the figure, 1...Frame, 2...Support shaft, 3...
Developing device, 4...Spring, I L=7-, example
Figure

Claims (1)

[Claims] [1] A developing device (
3) is swingably supported, while the spring (4) urges the developing device (3) in a direction approaching the photoreceptor (5), so that both ends of the developing device (3) in the direction of the swing axis are supported. In a developer pressing mechanism configured to have a photoreceptor (5) receive a pair of gap rollers (6) rotatably supported by a portion, the developer (3) is placed at an equal distance from both gap rollers (6). It is swingably connected to the support shaft (2) via a pin (8) at the position , and the axis of this pin (8) is aligned with the support shaft (2) and the developing device (3
) and the axis of both gap rollers (6), or perpendicular to the plane.