JPH07146634A - Process cartridge - Google Patents

Abstract

PURPOSE:To provide a process cartridge capable of stably obtaining a high-quality image by always keeping SD pressing force constant regardless of the quantity of developer in a developing unit and preventing irregularities in the image. CONSTITUTION:In this process cartridge 1 constituted by making a cleaning container 3 supporting the photosensitive drum (image carrier) 5 of an image forming device separate from a developing container (developing unit) 2 and coupling and integrating both containers 2 and 3; a connecting point(coupling position) O between both containers 2 and 3 is set on or near a perpendicular N passing the center of gravity G of the container 2. Then, moment around the connecting point O by the weight (in which the weight of developer (t) is included) (mg) of the container 2 acting on the center of gravity G is zero or a value small enough to be neglected, and the weight (mg) of the container 2 does not contribute to the SD pressing force (abutting force of both containers 2 and 3) P at all. Therefore, the SD pressing force P is generated only by the tensile force F of a pressing spring 12, and the SD pressing force is always kept constant regardless of the weight (rag) of the container 2, that is, the quantity of the developer (t) in the container 2, thereby accomplishing the purpose.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge loaded in an image forming apparatus using electrophotography.

[0002]

2. Description of the Related Art An image forming apparatus such as a printer forms a latent image on a photosensitive drum, which is an image carrier, which is uniformly charged, by selectively exposing the latent image on the photosensitive drum. The toner image is visualized and the toner image is transferred to a recording medium to perform image recording. In such an image forming apparatus, when the toner runs out, the toner must be replenished each time, but this toner replenishment work is not only troublesome, but it may be contaminated. Moreover, maintenance of each member can be performed only by a specialized service person, and this is often inconvenient for the user.

Therefore, the photosensitive drum, the charging device, the developing device, the cleaning device, etc. are integrated into a unitary structure to form a process cartridge, so that the user mounts the process cartridge in the main body of the image forming apparatus. Replenishment and replacement of parts such as the photosensitive drum that have reached the end of their life are made possible to facilitate maintenance.

By the way, as shown in FIG. 5, a process cartridge 101 includes a toner container and a developing container (hereinafter collectively referred to as a developing container) 102 integrated by welding.
And the cleaning container 103 are combined.

FIG. 6 shows the combined structure of the developing container 102 and the cleaning container 103.
A photosensitive drum 105 is rotatably held by 03, and a developing roller 104 is rotatably held by the developing container 102.

Then, the pin 107 protruding from the developing container 102 is provided with the hole 108 formed in the cleaning container 103.
, And the circlip 109 is fitted into the groove 107a formed at the tip of the one (longer) pin 107 to stop the thrust direction of the developing container 102 and the cleaning container 103. Protruding protrusion 1
By tensioning a CD pressure spring (tensile spring) 112 between 10 and a protrusion 111 provided on both sides of the cleaning container 102, the developing container 102 and the cleaning container 103 are joined in a contact state. There is. Therefore, the photosensitive drum 105 of the cleaning container 103 and the developing roller 104 in the developing container 102 are in contact with each other at a predetermined pressure.
This contact force (hereinafter referred to as SD pressure) P is the tensile force F of the CD pressure spring 112 and the weight mg of the developing container 102.
(M is the mass of the developing container 102 containing the developer t, and g is the gravitational acceleration) and is given by the force (moment force) accompanying the moment M.

In the moment M, the rotation center (coupling point) of the developing container 102 with respect to the cleaning container 103 is O, as shown in FIG. 1, and the weight mg of the developing container 102 acts from this rotation center O. When the distance to the line is L, it is expressed by the following equation.

[0008]

[Equation 1] M = mg · L

[0009]

By the way, in the conventional process cartridge 101, the rotation center (coupling point) O between the developing container 102 and the cleaning container 103 is
The developing container 102 is set at a position where it can be suspended from the cleaning container 103. In this case, since a large amount of the developer t is stored in the developing container 102 at the initial stage of use, the weight of the developer t is large, and thus the weight mg of the developing container 102 is large. Therefore, the S
A predetermined SD pressure P is obtained by the large moment force together with the compression force of the D pressure spring 112.

However, recently, it has been desired to reduce the cost per print, and as a result, the print life of the process cartridge 101 increases, and the storage capacity of the developer t in the developing container 102 increases accordingly. I'm doing it.

Further, since the predetermined SD pressing force P must be ensured even at the end of the durability, the CD pressure spring 112
In view of the fact that the pulling force of is required to be a certain value or more regardless of the increase of the developer t due to the change of the print life, if the print life is increased and the capacity of the developer t is increased, it is more than necessary at the beginning of use. The SD pressing force P is applied, and the spacer member 109 for maintaining a predetermined distance between the photosensitive drum 105 and the developing roller 104 is deformed by the excessive SD pressing force P, which causes image distortion. was there.

Further, the torque for rotating the photosensitive drum 105 fluctuates with the increase / decrease in the SD pressure P, and it is impossible to stably output a high quality image.

The present invention has been made in view of the above problems, and an object of the present invention is to always keep the SD pressure constant regardless of the amount of the developer in the developing unit to prevent the image disturbance. It is to provide a process cartridge capable of stably obtaining a high quality image.

[0014]

In order to achieve the above object, the present invention provides a unit for supporting an image carrier of an image forming apparatus using electrophotography and a developing unit as separate units, and both units are integrally connected. In the process cartridge configured as described above, the connecting position of both units is set on a vertical line passing through the center of gravity of the developing unit or in the vicinity thereof.

[0015]

According to the present invention, the connecting position (rotation center) of the developing unit with respect to the other units is set on the vertical line passing through the center of gravity of the developing unit or in the vicinity thereof, so that it depends on the weight of the developing unit acting on the center of gravity. The moment around the coupling position becomes 0 or negligibly small, and the developing unit weight does not contribute to the SD pressure (contact force between both units).

Therefore, the SD pressure force is generated only by the tensile force of the pressure spring, for example, and the weight of the developing unit, that is,
The SD pressure is always kept constant regardless of the amount of developer in the developing unit. Therefore, there is no longer a state in which the SD pressure becomes excessive at the initial stage of use of the process cartridge in which the amount of developer is large and the weight of the developing unit is large.
Since there is no change in the SD pressure force due to the change in the weight of the developer due to use, for example, the spacer member for maintaining a predetermined distance between the image carrier and the developing roller may be deformed by the excessive SD pressure force. The occurrence of image distortion can be prevented.

Further, since the torque fluctuation of the image carrier due to the change of the SD pressure is eliminated, a high quality image can be stably obtained.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a sectional view of a process cartridge according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view showing a coupling structure of the process cartridge.

The process cartridge 1 according to this embodiment is also constructed by connecting the developing container 2 and the cleaning container 3 in the same manner as in the conventional case, the developing roller 4 is supported by the developing container 2, and the photosensitive drum is provided in the cleaning container 3. 5 are supported.

Thus, in this embodiment, the developing container 2
Ribs 6 are provided on the upper surface of the ribs so as to project in the width direction at appropriate intervals, and pins 7 are horizontally provided on each rib 5.

As shown in FIG. 1, the pin 7 is provided on a vertical line N passing through the center of gravity G of the developing container 2, and a groove 7a is formed at the tip of one (longer) pin 7. ing.

On the other hand, arm portions 3a are horizontally extended integrally from the left and right ends of the upper surface of the cleaning container 3 toward the developing container 2 side, and the pins 7 are fitted to the tip portions of the respective arm parts 3a. A hole 8 to be fitted is provided.

Here, FIG. 2 shows the connecting structure of the developing container 2 and the cleaning container 3. The pin 7 provided on the developing container 2 side is formed at the tip of the arm portion 3a of the cleaning container 3. One of the pins (longer) that fits in the hole 8
A circlip 9 is fitted into the groove 7a formed at the front end of the developing container 2 to stop the thrust direction of the developing container 2 and the cleaning container 3, and the protrusion 10 provided on both side surfaces of the developing container 2 and both sides of the cleaning container 3 By stretching the CD pressure spring (tensile spring) 12 between the protrusion 11 provided on the surface and the protrusion 11, the developing container 2 and the cleaning container 3 are joined in a contact state.

Thus, in the present embodiment, the center of rotation O of the developing container 2 with respect to the cleaning container 3 (the pivot point of the pin 7) is located on the vertical line N passing through the center of gravity G of the developing container 2, so that the center of gravity is The moment M about the rotation center O due to the weight mg of the developing container 2 acting on G (m is the mass of the developing container containing the developer t, g is the gravitational acceleration) is M = 0 (that is,

In Equation 1, L = 0, and the weight m of the developing container 2
g does not contribute to the SD pressure (contact force between the developing container 2 and the cleaning container 3) P at all.

Therefore, in this embodiment, the SD pressure P is generated only by the tensile force F of the CD pressure spring 12, and the weight mg of the developing container 2, that is, the developer t in the developing container 2.
The SD pressure P (= F) is always kept constant regardless of the amount of. Therefore, the SD pressure P does not become excessively large at the initial stage of use of the process cartridge 1 in which the amount of the developer t is large and the weight of the developing container 2 is large. Since there is no change in P, the spacer member 13 for maintaining the predetermined distance between the photosensitive drum 5 and the developing roller 4 is not deformed by the excessive SD pressure P, and the occurrence of image distortion is prevented. Be done.

Further, since the torque fluctuation of the photosensitive drum 5 due to the change of the SD pressure P is also eliminated, a high quality image can be stably obtained.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. 3 is a sectional view of the process cartridge according to the second embodiment, and FIG. 4 is an exploded perspective view showing the coupling structure of the process cartridge. In these figures, the same elements as those shown in FIGS. 1 and 2 are shown. Are denoted by the same reference numerals, and description thereof will be omitted below.

In the process cartridge 1 according to the present embodiment, ribs 6 project from the lower surface of the developing container 2 and pins 7 are provided on these ribs, and a pair of left and right arm portions 3a extends on the lower surface of the cleaning container 3. The pin 7 provided on the developing container 2 side is fitted into the hole 8 formed at the tip of the arm 3a of the cleaning container 3, and is formed at the tip of one (longer) pin 7. Further, the circlip 9 is fitted in the groove 7a to stop the thrust direction of the developing container 2 and the cleaning container 3, and the protrusion 10 protruding on both side faces of the developing container 2 and the both side faces of the cleaning container 3 are protruded. C between the protrusion 11
By stretching the D pressure spring (tensile spring) 12,
The developing container 2 and the cleaning container 3 are joined together in a contacting state.

Thus, also in this embodiment, the pin 7 is perpendicular to the center of gravity G of the developing container 2 as in the first embodiment.
The cleaning container 3 provided on the cleaning container 3 for the developing container 2
The rotation center O with respect to is located on the vertical line N.

Therefore, also in this embodiment, the moment M about the center of rotation O due to the weight mg of the developing container 2 acting on the center of gravity G becomes M = 0, and the SD pressure P is the tensile force of the CD pressure spring 12. Since the SD pressure P (= F) is always maintained constant regardless of the weight mg of the developing container 2, that is, the amount of the developer t in the developing container 2, it is generated only by F. The same effect as can be obtained.

According to the experiment, the center O of rotation of the developing container 2
Does not necessarily have to be located exactly on the vertical line N passing through the center of gravity G of the developing container 2, and a sufficient effect can be obtained if it is located within an angle range of ± 20 ° with respect to the vertical line N with the center of gravity G as a fulcrum. Do you get it. If the rotation center O is located within this angle range of ± 20 °, about 35% of the weight mg of the developing container 2 is added to the SD pressure P, and the value is such that the developing container 2 can print 6000 sheets, for example. In some cases, it will be 315 g, and the spring pressure for maintaining SD pressure P is about 1000 g.
Will be very small with no effect on.

[0033]

As is apparent from the above description, according to the present invention, the unit for supporting the image carrier of the image forming apparatus using the electrophotographic technique and the developing unit are provided separately, and both units are combined and integrated. In the process cartridge configured as an integrated unit, the connecting position of both units is set on the vertical line passing through the center of gravity of the developing unit or in the vicinity thereof, so the SD pressure is always kept constant regardless of the amount of developer in the developing unit. It is possible to stably obtain high quality images by preventing image distortion.

[Brief description of drawings]

FIG. 1 is a sectional view of a process cartridge according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the coupling structure of the process cartridge according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a process cartridge according to a second embodiment of the present invention.

FIG. 4 is an exploded perspective view showing the connecting structure of the process cartridge according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional process cartridge.

FIG. 6 is an exploded perspective view showing a coupling structure of a conventional process cartridge.

[Explanation of symbols]

1 Process Cartridge 2 Developing Container (Developing Unit) 3 Cleaning Container (Unit Supporting Image Bearing Body) 4 Developing Roller 5 Photosensitive Drum (Image Bearing Body) 12 CD Pressing Spring O Rotation Center (Coupling Position) P SD Pressure

Claims (2)

[Claims] 1. A process cartridge constituted by combining a unit for supporting an image carrier of an image forming apparatus using electrophotography and a developing unit as separate units, and combining the units into a united position. Is provided on or near a vertical line passing through the center of gravity of the developing unit. 2. The process cartridge according to claim 1, wherein the connecting position of the both units is set within an angle range of ± 20 ° with respect to the perpendicular with the center of gravity of the developing unit as a fulcrum.