KR101050530B1 - Developing apparatus with tolerance absorbing structure - Google Patents

Abstract

The present invention relates to a developing apparatus, comprising: a developing roller having a gap holding device at both ends thereof, a developing unit including a developing roller housing for supporting the developing roller, and protrusions provided on both sides of the developing roller housing; And a photosensitive unit including a photosensitive drum mounted to face the developing roller, a first drum housing having a first coupling boss, and a second drum housing having a second coupling boss. The inner area is larger than the cross-sectional area of the protrusion, and the inner area of the first coupling boss corresponds to the cross-sectional area of the protrusion, and the gap holding device of the developing roller and the photosensitive drum are in contact with each other, so that the developing roller and the photosensitive drum A developing device is characterized in that the gap is kept constant.

According to the present invention, even if there is a processing tolerance generated during processing of each component constituting the developing apparatus, it is absorbed on the coupling boss so that the developing roller and the photosensitive drum are coupled in parallel, so that both ends of the developing roller are combined. Since the gap retaining apparatus located in the part and the photosensitive drum are in contact with each other, the gap and the gap between the developing roller and the photosensitive drum can be kept constant, so that print quality can be improved.

Developing device. Developing roller, photosensitive drum, tolerance, combine boss, long hole.

Description

Developing apparatus having a tolerance absorbing structure {Process cartridge with tolerance relief structure}

1 is an exploded perspective view showing a combined state of a conventional developing apparatus.

FIG. 2 is a perspective view schematically illustrating a state in which the photosensitive drum and the developing roller are incorrectly coupled due to a tolerance in the developing apparatus shown in FIG. 1.

Fig. 3 is a perspective view showing a developing unit portion of an embodiment of a developing apparatus of an image forming apparatus having a tolerance absorbing structure according to the present invention.

FIG. 4 is a perspective view illustrating only the first drum housing, the second drum housing, and the fixed shaft portion of the embodiment illustrated in FIG. 3.

FIG. 5 is a plan view illustrating a coupling boss of the second drum housing in the embodiment illustrated in FIG. 4.

Fig. 6 is a diagram corresponding to Fig. 4 of another embodiment of the developing apparatus of the image forming apparatus having the tolerance absorbing structure according to the present invention.

FIG. 7 is a plan view illustrating a coupling boss of the second drum housing in the embodiment illustrated in FIG. 6.
8 is a diagram corresponding to FIG. 4 of another embodiment of the developing apparatus of the image forming apparatus having the tolerance absorbing structure according to the present invention.

delete

FIG. 9 is a plan view illustrating a coupling boss of the second drum housing in the embodiment illustrated in FIG. 8.

<Explanation of symbols for main parts of the drawings>

10... Photosensitive unit, 12... Charging roller,

14. Photosensitive drum, 20... First drum housing,

22. Combined boss, 30... Developing unit,

32…. Developing roller, 34... Fixed shaft,

34a, 34b... Projections 140... Second drum housing,

142. Combined boss, 144... Protrusion receptor,

146. Coil spring.

The present invention relates to a developing apparatus, and more particularly, a developing unit which is a combination of a developing unit that serves to store and supply toner in an image forming apparatus, and a photosensitive unit that transfers an image having a latent image formed and developed onto a printing medium. It is about.

The electrophotographic image forming apparatus forms a latent image on the surface of a photosensitive member such as a photosensitive drum charged through a laser scanning unit, and then develops a developer such as a toner on the surface of the photosensitive member and transfers it to a print medium. After that, the printing process is performed by fixing.

Here, the photosensitive unit is composed of one unit including a photosensitive drum and a charging roller for charging the photosensitive drum to a potential of a desired size. The photosensitive unit has a storage space for storing toner and a developing roller for developing toner on the photosensitive drum. And a supply roller or the like for supplying toner to the developing roller as a unit is called a developing unit, and an assembly in which the photosensitive unit and the developing unit are combined is called a developing apparatus. Of course, the photosensitive unit and the developing unit include other components which are not described, but the description thereof will be omitted for convenience since they are not directly related to the present invention.

1 shows a conventional general developing apparatus. As shown, the charging roller 12 is rotatably mounted on the rear surface of the photosensitive unit 10, and the photosensitive drum 14 is in contact with the charging roller 12 at the lower portion of the charging roller 12. It is rotatably mounted. On the other hand, the developing unit 30 is mounted toward the photosensitive drum 14 of the photosensitive unit 10. A space for storing toner is formed inside the developing unit 30, and a developing roller 32 mounted to face the photosensitive drum 14 is mounted on a front surface of the developing unit 30. Meanwhile, the developing unit 30 includes a developing roller housing 35 for supporting the developing roller 32, and the photosensitive unit 10 supports the charging roller 12 and the photosensitive drum 14. It comprises a first drum housing 20 and the second drum housing 40 for the purpose.

The photosensitive unit 10 and the developing unit 30 are coupled by the first drum housing 20 and the second drum housing 40 located at both sides. That is, in FIG. 1, the photosensitive drum of the photosensitive unit is fixed to the front part of the first and second drum housings, and on both sides of the developing unit 30 to the coupling bosses 22 and 42 of the first and second drum housings. The protrusions 34a and 34b which are positioned are rotatably mounted to form a coupling. In this case, referring to FIG. 2, separate gap holding devices 33 are positioned at both ends of the developing roller 32, and the developing roller 32 and the photosensitive drum 14 are disposed by the gap holding devices 33. This constant gap and nip are maintained. That is, the gap holding device 33 located at both ends of the developing roller 32 contacts the photosensitive drum 14, so that the gap and gap between the developing roller 32 and the photosensitive drum 14 can be kept constant. have.

Here, the developing unit 30 is mounted in a state where the developing roller 32 is pressed toward the photosensitive drum 14 by the weight of the developing unit, so that toner adhered to the surface of the developing roller can be smoothly transferred to the photosensitive drum. To help.

Therefore, although the photosensitive drum and the developing roller must be accurately aligned for excellent print quality, it is true that the exact alignment is difficult due to the processing tolerances of each product. That is, the developing roller should be positioned parallel to the photosensitive drum. For this purpose, the virtual straight line connecting the coupling boss should be parallel to the central axis of the photosensitive drum, but the processing tolerances of the developing unit and the first and second drum housings Machining tolerances are cumulative and it is difficult to match them exactly. As a result, as shown in FIG. 2, the developing roller 32 and the photosensitive drum 14 are disposed to be offset so that the gap retaining device is located at either one of both ends (the right end in FIG. 2) of the developing roller 32. Since the 33 does not come into contact with the photosensitive drum 14, the gaps and gaps between the developing roller 32 and the photosensitive drum 14 are not kept constant, and there is a great risk of deterioration in print quality.

The present invention has been made to overcome the drawbacks of the prior art as described above, by adding a structure that can absorb the processing tolerance to the drum housing that combines the developing unit and the photosensitive drum of the photosensitive unit to absorb the processing tolerance occurs It is a technical problem to provide a developing device capable of accurately placing a photosensitive drum and a developing roller.

In order to achieve the above technical problem, the present invention includes a developing roller having a gap holding device at both ends, a developing roller housing for supporting the developing roller, and protrusions provided at both sides of the developing roller housing, respectively. Developing unit; And
A photosensitive unit including a photosensitive drum mounted to face the developing roller, a first drum housing having a first coupling boss, and a second drum housing having a second coupling boss,
The inner area of the second coupling boss is larger than the cross-sectional area of the protrusion, and the inner area of the first coupling boss corresponds to the cross-sectional area of the protrusion,
A gap holding device of the developing roller and the photosensitive drum are in contact with each other, so that the gap between the developing roller and the photosensitive drum is kept constant.

That is, in the present invention, the coupling boss formed in one of the first drum housing and the second drum housing supporting the protrusion of the developing unit is larger than the protrusion formed in the developing unit, and preferably the coupling boss corresponds to the diameter of the protrusion. It is designed to absorb the machining tolerance in the form of a long hole extending with a width. As a result, an imaginary straight line connecting the center of the coupling boss of the first drum housing and the second drum housing is parallel to the central axis of the photosensitive drum due to processing tolerances of the first drum housing, the second drum housing, and the developing unit. If not, the photosensitive drum and the developing roller can be arranged in parallel with each other, since the processing tolerance can be absorbed in the long boss-shaped coupling boss, so that the gap retaining device located at both ends of the developing roller and the photosensitive drum are in contact with each other. Thus, the gap and gap between the developing roller and the photosensitive drum can be kept constant.

On the other hand, the direction of the processing tolerance that can be absorbed is determined by the direction in which the coupling boss of the long hole type is arranged, preferably the coupling boss of the long hole type is the center of the developing roller installed in the developing unit, and the photosensitive unit It is preferable to extend in parallel with a straight line connecting the center of the photosensitive drum installed therein. Whether or not the toner of the developing roller is properly transferred to the photosensitive drum is determined by the distance between the developing roller and the photosensitive drum, so that the direction of the absorbed processing tolerance is parallel to the straight line connecting the central axis of the developing roller and the photosensitive drum. The spacing is to be constant by the coupling boss in the form of a long hole.

Preferably, the protrusion receptor is mounted inside the coupling boss of the long hole shape, and it is preferable to insert an elastic means between the protrusion receptor and the inner wall of the coupling boss. Due to the elastic force of the elastic means, the protrusions are firmly supported without moving in the coupling boss, and the protrusions can be stably supported by the protrusion receptor.

The protruding portion receptor may be configured in any form, for example, one side of the protruding portion receptor is in contact with the protruding portion, and has a curved surface corresponding to the shape of the outer peripheral surface of the protruding portion, one end of the elastic means is fixed to the opposite side It may be configured in the form.

On the other hand, the coupling boss of the long hole shape does not necessarily have to be a straight line may be made of a curve. In addition, it is possible to have a structure that can absorb the tolerance regardless of the direction of the processing tolerance by having an area larger than the projection and having an elastic body on the inner wall.

Hereinafter, embodiments of a developing apparatus of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are assigned to the same parts in the following description, and duplicate descriptions will be omitted. At this time, the developing apparatus of the image forming apparatus according to the present invention may be the same as that of the conventional general developing apparatus of FIG.

3 shows a first embodiment of a developing apparatus. 3 illustrates a state in which the developing unit 30 and the photosensitive drum 14 are coupled to each other, and the protrusion 34b of the developing unit is connected to the second coupling boss 142 of the second drum housing 140. It is fitted. The second coupling boss 142 has an extended shape as compared with the conventional coupling boss. That is, the width of the second coupling boss 142 is equal to the diameter of the protrusion 34b, but the length is larger than the diameter of the protrusion so as to have a clearance capable of absorbing the processing tolerance. Meanwhile, the developing unit 30 includes a developing roller housing 35 for supporting the developing roller 32, and the photosensitive unit includes a first drum housing for supporting the charging roller and the photosensitive drum 14. Not shown) and the second drum housing 140.

FIG. 4 illustrates only the first drum housing 20, the second drum housing 140, and the fixed shaft 34 of the components of the exemplary embodiment illustrated in FIG. 3. Projections 34a and 34b are positioned at both ends of the fixed shaft 34.

First, the first coupling boss 22 of the first drum housing 20 has a size corresponding to the diameter of the protrusion 34a as in the related art and serves as a reference point for fixing. The opposite protrusion 34b (see FIG. 5) is fitted inside the second coupling boss 142 of the second drum housing 140. The second coupling boss 142 has a curved surface corresponding to the outer surface of the protrusion 34b on one side and is supported in contact with the protrusion 34b, and one end of the coil spring 146 is fixed to the other side. The protruding portion receptor 144 is inserted. The other end of the coil spring 146 is fixed to the inner wall of the coupling boss 142.

Therefore, even when there is a processing tolerance, after the photosensitive drum and the developing roller are positioned in parallel, the protrusions 34a and 34b are inserted into the coupling bosses 22 and 142, and then the first drum housing and the second drum housing are coupled to each other. Since the 34b is moved by the accumulated processing tolerance, the photosensitive drum and the developing roller can be kept in parallel. Therefore, the gap retaining devices located at both ends of the developing roller and the photosensitive drum are brought into contact with each other. The gaps and gaps of the rollers and the photosensitive drum can be kept constant. At this time, since the protrusion 34b is firmly supported by the elastic force of the coil spring, it may block the occurrence of vibration or noise due to play during operation.

The coupling bosses 22 and 142 may be arranged in various directions. As shown in FIG. 4, the coupling bosses 22 and 142 extend in parallel with a straight line connecting the center of the photosensitive drum and the center of the developing roller. It is advantageous to make sure that it is arranged.

On the other hand, the coupling boss may be arranged in a curved shape as shown in FIG. 6 and 7, the outer circumferential portion of the second coupling boss 242 formed in the second drum housing 140 has a curved shape unlike in FIG. 4, and has a shape similar to that shown in FIG. 4. The protrusion part receptor 244 having a protrusion is mounted, and the surface contacting the inner wall of the second coupling boss 242 of the protrusion part receptor 244 is formed to match the curve formed by the inner wall surface of the second coupling boss 242. At one end, a coil spring 246 is mounted.

According to the second coupling boss 242 illustrated in FIG. 6, the processing tolerance may be absorbed in the up, down, left, and right directions. However, it is not possible to independently absorb processing tolerances in the vertical direction and the left and right directions.

8 and 9, there is shown an embodiment having yet another form of engagement boss. In this embodiment, the coupling boss 342 is in the form of a dilator rather than a long hole. That is, the coupling boss 342 is formed to be larger than the cross-sectional area of the protrusion 34b, and the protrusion boss 344 is mounted therein so as to flow up, down, left, and right. The protrusion part receptor 344 has a ring shape, and the protrusion part is inserted therein. Meanwhile, four coil springs 346 are disposed at 90 ° intervals between the outer surface of the protrusion receptor 344 and the inner wall of the coupling boss 342. The number of coil springs is determined by the size of the coupling boss and the protrusion receptor. Therefore, it can be changed appropriately.

In the case of the embodiment shown in Figure 8 it can absorb the machining tolerance independently in the up, down, left and right directions. Therefore, it has excellent work tolerance absorbency as compared with other embodiments.

According to the present invention having the above-described configuration, even if there is a machining tolerance generated during the processing of each component constituting the developing apparatus, it is absorbed on the coupling boss so that the developing roller and the photosensitive drum are coupled in parallel. In addition, the gap retaining devices positioned at both ends of the developing roller and the photosensitive drum are in contact with each other, so that the gap and the gap between the developing roller and the photosensitive drum can be kept constant, thereby improving print quality.

In addition, changes in component stiffness due to long-term use during operation of the product or deformation of the component form due to changes in environmental conditions such as temperature or humidity can also be absorbed on the mating boss, thereby improving the durability of the product. .

Claims (10)

A developing unit including a developing roller having a gap holding device at both ends, a developing roller housing for supporting the developing roller, and protrusions provided at both sides of the developing roller housing; And A second drum housing having a photosensitive drum mounted to face the developing roller, a first drum housing having a first coupling boss for fitting one of the protrusions, and a second coupling boss for fitting the other one of the protrusions; Including a photosensitive unit, The inner area of the second coupling boss is larger than the cross-sectional area of the protrusion, and the inner area of the first coupling boss corresponds to the cross-sectional area of the protrusion, And the gap between the developing roller and the photosensitive drum is kept constant by the gap holding device of the developing roller and the photosensitive drum. The method of claim 1, And the width of the second coupling boss is equal to the diameter of the protrusion, and the length of the second coupling boss is larger than the diameter of the protrusion. The method of claim 2, And the length of the second coupling boss is in the form of a long hole extending in parallel with a straight line connecting the center of the photosensitive drum and the center of the developing roller. The method of claim 3, And a projection receptor is mounted inside the second coupling boss, and an elastic means is inserted between the projection receptor and the inner wall of the second coupling boss. The method of claim 2, The second coupling boss is a developing device, characterized in that the long hole shape extending while drawing a curved trajectory. The method of claim 5, The protrusion receptor is mounted inside the second binding boss, The developing device, characterized in that the surface in contact with the inner wall of the second coupling boss of the projection receptor is formed to match the curve formed by the inner wall surface of the second coupling boss. The method of claim 6, And a coil spring positioned at one end of the protrusion receptor. The method of claim 1, The second coupling boss is in the form of expansion, the developing device, characterized in that the protrusion receptor is mounted inside the second coupling boss so as to flow up, down, left and right. The method of claim 8, And a coil spring disposed between an outer surface of the protrusion receptor and an inner wall of the second coupling boss. The method of claim 1, Any one of the protrusions is fixed to the first coupling boss so as not to flow with respect to the first drum housing, and the other one of the protrusions is fitted to the second coupling boss and spaced apart.

Images