JPH08202145A - Developing device - Google Patents

Abstract

PURPOSE: To prevent the thermal contraction of a housing from being transmitted to a developing blade and to always obtain a good image. CONSTITUTION: The developing blade 3 is attached to the housing 2 for the developing device through a holding plate 1, the holding plate 1 is a long sheet member in a side cross section shape that a 1st face part 11 and a 2nd face part 12 are mutually open at a prescribed angle, being bounded by a bent part, and both end parts of the 1st board part 11 in a longitudinal direction are fixed on an attachment corner part 14 formed on the housing 2 in a state where the inside corner 13 of the plate 1 faces toward the attachment corner part 14 and a space 16 is formed on the outside corner 15, the housing 2 is provided with a holding plate pressing member 20 for pressing the central part of the surface on the outside corner 15 side of the plate 1, then, the holding plate 1 is prevented from being deformed due to the thermal contraction of the housing 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device provided in an image forming apparatus such as an electrophotographic copying machine and a laser printer, and more particularly to a developing apparatus having an improved mounting method of a developing blade used therein.

[0002]

2. Description of the Related Art As a developing device used for developing an electrostatic latent image formed on an image carrier in an image forming apparatus such as the above electrophotographic copying machine, a developing roller provided with a developing roller is used. There is known a developing device of a type in which the above-mentioned developer is applied while the layer thickness of the developer is uniformly regulated by a developing blade brought into contact with a developing roll. Japanese Patent Laid-Open No. 3-62059 discloses an example of such a developing device. In this publication, as shown in FIGS. 12 and 13, a long plate member having an L-shaped cross section is used as a holding plate (holding member) 1, which is attached to the housing 2 of the developing device via the holding plate 1 and has a front end. There is disclosed a developing blade 3 that elastically contacts a developing roll (not shown). In this case, the holding plate 1 is screwed to the housing 2 at both ends.

[0003]

The image forming apparatus such as the copying machine has been downsized, and the developing apparatus is also desired to be downsized as much as possible. As a means for this, the member itself has been made smaller and thinner, and also in the developing blade 3, the holding plate 1 for holding the developing blade 3 and attaching it to the housing 2 is made thin or downsized. There is a tendency.
In order to make the holding plate 1 thinner or smaller than before, a metal such as stainless steel is usually selected as the material in order to obtain a material having sufficient strength. On the other hand, the housing 2 to which the holding plate 1 is attached is generally made of a resin such as ABS.

In an image forming apparatus such as a copying machine, each member undergoes thermal contraction under the environmental conditions of use, which is particularly noticeable in a low temperature environment. By the way, as described above, in the resin housing 2 and the metal holding plate 1, the housing 2 has a larger coefficient of thermal contraction (coefficient of thermal expansion). It is fully conceivable that the holding plate 1 whose both ends are screwed is affected by the contraction of the housing 2 and deforms from its shape in a direction in which the outside (outer corner side) is warped. The arrow in FIG. 13 indicates heat shrinkage in the housing 2.
The direction of thermal expansion is shown. Thus holding plate 1
14 is deformed, the developing blade 3 is distorted from the center in the longitudinal direction and is deformed in a wavy manner, as shown in FIG.
If the developer is brought into contact with the developing roll in this state, the layer thickness of the developer becomes non-uniform in the axial direction, resulting in uneven charging, and uneven density in the developed image. When thermal expansion occurs, the holding plate 1 is pulled in both end directions and receives a force, so that the holding plate 1 is not deformed enough to affect development.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a developing device in which the influence of heat contraction on the developing blade is suppressed and a good image is always obtained without uneven charging. I am trying.

[0006]

To achieve the above object, in a developing device according to a first aspect of the present invention, a developing chamber provided in a housing is housed so as to face an image carrier such as a photosensitive drum. And a developing blade fixed to the housing in parallel with the developing roll via a holding plate made of a material different from that of the housing and contacting the developing roll with a predetermined contact pressure. Is a long plate member having a cross-sectional shape in which the first surface portion and the second surface portion open at a predetermined angle with respect to the bent portion, the inner corner side of which is directed to the mounting corner portion formed in the housing and the outer portion. In a developing device in which both longitudinal ends of the first plate portion are fixed to the mounting corners with a space left on the corner side, the outer corner side surface of the holding plate is pushed onto the housing. It is characterized in structure in which a holding plate holding member to obtain.

According to a second aspect of the present invention, in the developing device according to the first aspect, the holding plate pressing member is detachably attached to the housing at a plurality of positions along the longitudinal direction of the holding plate. It has a feature. Also,
According to a third aspect of the present invention, in the developing device according to the first aspect, the holding plate pressing member is made of an elastic material and elastically presses the outer corner side surface of the holding plate. I am trying. Further, the developing device according to a fourth aspect is the developing device according to the first aspect, characterized in that the holding plate pressing member is formed integrally with the housing.

According to a fifth aspect of the present invention, in the developing device, a developing chamber accommodated in a housing is provided with a developing roller housed in the developing chamber so as to face an image bearing member such as a photosensitive drum. A developing blade that is fixed in parallel with the developing roll via a holding plate made of a different material, and abuts on the developing roll at a predetermined abutting pressure; A long plate member having a cross-sectional shape in which two surface portions are opened at a predetermined angle to each other, the inner corner side of which is directed to the mounting corner portion formed in the housing, and the outer corner side is provided with a space, (1) In a developing device in which both longitudinal ends of the plate portion are fixed to the mounting corners by screwing screws into the mounting corners, the screws passing through the screw through holes formed in the both ends are , Is characterized in structure in which the movable means movable relative to the longitudinal direction of the serial holding plate relative to the housing.

According to a sixth aspect of the present invention, in the developing apparatus according to the sixth aspect, a protrusion is provided on one of opposing surfaces of the mounting plate and the mounting corner of the housing, and the protrusion is provided on the other opposing surface. It is characterized by being brought into contact with.

[0010]

According to the developing device of the present invention, the deformation force applied to the holding plate from the housing due to the difference in thermal contraction due to the difference in material is suppressed by the holding plate pressing member, and the deformation of the holding plate is prevented. The developing blade attached to the holding plate is also kept in a normal state, and the layer thickness of the developer supplied to the developing roll is always made uniform by the developing blade regardless of temperature change, and good images can be obtained without uneven charging. To be

[0011]

Embodiments of the present invention will be described below with reference to the drawings. A. First Embodiment (Claim 1) [Configuration of First Embodiment] FIG. 1 shows a first embodiment of the present invention. In these figures, a metal holding plate 1, a resin housing 2 and a developing blade 3 similar to the developing device of FIG. 12 are shown. In addition, the holding plate 1 is a long plate member having an L-shaped cross section in which the first plate portion (first surface portion) 11 and the second plate portion (second surface portion) 12 are orthogonal to each other. Then, with the inner corner 13 side facing the mounting corner portion 14 formed in the housing 2 and the space 16 left on the outer corner 15 side, both longitudinal ends of the first plate portion 11 are mounted at the mounting corner portion. It is being fixed to 14 by the screw S1. The developing blade 3 is attached to the outer surface side of the first plate portion 11 by means such as adhesion with an adhesive material, and the tip of the developing blade 3 is housed in a developing chamber 2a formed in the housing 2 (not shown). The developing roller is brought into contact with the peripheral surface of the developing roller under a predetermined contact pressure.

Only the first plate portion 11 of the holding plate 1 is in contact with the front surface 14a of the front surface 14a and the upper surface 14b which form the mounting corner portion 14 of the housing 2. A holding plate pressing member (hereinafter simply referred to as a pressing member) 20 that presses the central portion of the upper surface of the second plate portion 12 of the holding plate 1 is fixed to the upper surface 14b with a screw S2. The holding member 20 is a long plate member having an L-shaped cross section, which includes a long side plate portion 21 and a short side plate portion 22, and the short side plate portion 22 faces upward, and the long side plate portion 21 is the second plate portion of the holding plate 1. It is fixed to the housing 2 while pressing 12.

[Effects of the First Embodiment] According to the first embodiment, the force of the housing 2 shrinking more than the holding plate 1 and the holding plate 1 warping to the outer corner 15 side, that is, the space 16 side. Even when receiving, the pressing member 20 suppresses the deformation in that direction. When the holding plate 1 is not deformed, the developing blade 3 is not wavy and deformed, and the straight state is maintained. Therefore, the layer thickness of the developer supplied to the developing roll is always uniform, and good images can be obtained without causing uneven charging. Holding member 20
Has an L-shaped cross section and is extremely strong against bending of the holding plate 11 in the direction of deformation, so that the force for suppressing deformation is strong.

B. Second Embodiment (Claim 3) [Configuration of Second Embodiment] FIGS. 2 and 3 show a second embodiment of the present invention. In this case, as shown in FIG. 3, the first plate portion 11 of the holding plate 1 is thickened at both ends in the longitudinal direction and fastened to the mounting corner portions 14 of the housing 2, and thinned in the middle portion in the longitudinal direction. Installed corner 14
Away from. Further, the second plate portion 12 is fixed apart from the mounting corner portion 14. Mounting corner 1
A pressing member 20 that is bent in a crank shape in section and presses the central portion of the second plate portion 12 of the holding plate 1 from above is fixed to the upper surface 14b of No. 4 with a screw S3. The tip of the pressing member 20 is fixed to the second plate portion 12 of the holding plate 1 with bolts 25 and nuts 26. In this configuration, particularly, the pressing member 20 may be made of a material such as steel (stripes) so as to elastically press the second plate portion 12 of the holding plate 1.

[Operation and Effect of Second Embodiment] According to the second embodiment, the holding plate 1 and the pressing member 20 are connected by the bolts 25 and the nuts 26, so that the pressing member 2
The force of suppressing the deformation of the holding plate 1 due to 0 is strongly exerted. Further, when the holding member 20 is made of a material such as steel as described above, the holding plate 1 can be made thinner and the size thereof can be made smaller as the force for holding the holding plate 1 increases.

C. Third Embodiment (Claims 2 and 3) [Structure of Third Embodiment] FIGS. 4 and 5 show a third embodiment of the present invention. In this case, the holding member 20 that holds the second plate portion 12 of the holding plate 1 is composed of a leaf spring bent in a crank shape. The tip portion of the pressing member 20 forms an acute angle with respect to the intermediate portion extending upward, and holds the holding plate 1 with a stronger force. The upper surface 14b of the mounting corner portion 14 of the housing 2
A plurality of screw holes 30 for fixing the pressing members are provided at even intervals along the longitudinal direction of the holding plate 1, and an appropriate number of the pressing members 20 are fitted in these screw holes 30 and fixed by screws S2. It has become. Holding member 2
0 is attachable to and detachable from the housing 2, and the number of attachments is arbitrary.

[Effects of Third Embodiment] According to the third embodiment, the pressing member 2 is moved according to the rigidity of the holding plate 1.
By strengthening the leaf spring of 0, the cross section of the pressing member 20 itself can be reduced, and the number of the pressing members 20 and the mounting position can be selected.

D. Fourth Embodiment (Claim 4) [Configuration of Fourth Embodiment] FIG. 6 shows a fourth embodiment of the present invention. In this case, the receiving plate 40 is provided with bolts 41 from below in the central portion in the longitudinal direction of the second plate portion 12 of the holding plate 1.
-Fixed with the nut 42. On the other hand, at the mounting corner portion 14 of the housing 2, the pressing member 20 is integrally formed with the housing 2, and the receiving plate 40 is held by the pressing member 20 in the groove 43 on the front side formed by the pressing member 20. Is fitted so as to abut the lower surface of the. FIG. 7 shows a modification of the fourth embodiment. In this case, instead of the receiving plate 40, the second plate portion 12 of the holding plate 1 is extended, and the second plate portion 12 is directly fitted into the groove 43. ing.

[Operation and Effect of the Fourth Embodiment] According to the fourth embodiment, the deformation of the holding plate 1 due to the thermal contraction of the housing 2 is suppressed through the receiving plate 40. Since the pressing member 20 is formed integrally with the housing 2, it is not necessary to attach the pressing member 20 to the housing 2 as in the previous embodiments, and the number of parts can be reduced.

E. Fifth Embodiment (Claim 5) [Structure of the Fifth Embodiment] FIGS. 8, 9 and 10 show a fifth embodiment of the present invention. In this case, both ends in the longitudinal direction of the first plate portion 11 of the holding plate 1 are fixed to the front surface 14a of the mounting corner portion 14 of the housing 2 with the screws S1 as in the conventional case, but as shown in FIG. , The screw S1 is passed through the collar 50, which is higher than the thickness of the first plate portion 11, and the first plate portion 11 is not directly fastened to the housing 2. Moreover, as shown in FIG. 10, the screw through hole 51 is an elongated hole extending in the longitudinal direction of the holding plate 1. With this configuration, the holding plate 1 can be relatively moved in the longitudinal direction with respect to the housing 2 to some extent (amount of deformation or more). That is, the collar 50 and the screw hole 51 themselves are the movable means of the holding plate 1.

[Effects of the Fifth Embodiment] According to the fifth embodiment, the holding plate 1 is constructed so as not to receive the restraining force of the housing 2 in the longitudinal direction within the deformation range. Even when the housing 2 is thermally contracted, the housing 2 does not receive a deforming force by moving in the longitudinal direction relative to the housing 2.

F. Sixth Embodiment (Claim 6) [Structure of Sixth Embodiment] FIG. 11 shows a sixth embodiment of the present invention. In the sixth embodiment, in addition to the configuration of the fifth embodiment, a plurality of protrusions 60 are provided on the front surface 14a of the mounting corner portion 14 of the housing 2. In this case, the protrusions 60 are arranged in a pair above and below the screw S1 and are in contact with the inner surface of the first plate portion 11 of the holding plate 1.

[Operation and Effect of the Sixth Embodiment] According to the sixth embodiment, the holding plate 1 and the housing 2 have the protrusion 60.
Since it is in point contact with, the friction is reduced and the housing 2
Due to the heat contraction, the relative movement that occurs between the two smoothly progresses, and the prevention of deformation of the holding plate 1 is promoted.

[Modification] The present invention is not limited to the above-described embodiments, but various modifications can be made. For example, in the above embodiment, the first plate portion 11 and the second plate portion 12 of the holding plate 1 are orthogonal to each other, but the angle formed by them can be set to an obtuse angle or an acute angle. In addition, in the first embodiment, the second plate portion 12 is attached to the mounting corner portion 1.
Although it is separated from the upper surface 14b of No. 4, it can also be in contact. Further, in the second embodiment, the entire surface of the first plate portion 11 of the holding plate 1 is attached to the front surface 14a of the mounting corner portion 14.
Can be contacted with.

[0025]

As described above, according to the developing device of the present invention, the deforming force received by the holding plate from the housing due to the difference in heat shrinkage due to the difference in material is suppressed by the holding plate pressing member, and accordingly, The developing blade attached to the holding plate is also kept in a normal state, and as a result,
The layer thickness of the developer supplied to the developing roll is always made uniform by the developing blade irrespective of the temperature change, and a good image can be obtained without uneven charging.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a first embodiment of the present invention.

FIG. 2 is a perspective view of a second embodiment of the present invention.

FIG. 3 is a sectional view of an essential part of the second embodiment, FIG.
2 is a sectional view taken along the line AA of FIG. 2, (B) is a sectional view taken along the line BB of FIG. 2, and (C) is a sectional view taken along the line CC of FIG.

FIG. 4 is a perspective view of a third embodiment of the present invention.

FIG. 5 is a cross-sectional view of main parts of the third embodiment.

FIG. 6 is a cross-sectional view of essential parts of a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view of an essential part of a modified example of the fourth embodiment.

FIG. 8 is a perspective view of a fifth embodiment of the present invention.

FIG. 9 is a sectional view of an essential part of the fifth embodiment.

FIG. 10 is a plan view of an essential part of the fifth embodiment.

FIG. 11 is a cross-sectional view of essential parts of a sixth embodiment of the present invention.

FIG. 12 is a perspective view illustrating a conventional developing device.

FIG. 13 is an exploded perspective view of the device.

FIG. 14 is a perspective view showing a problem that the developing blade is deformed in the apparatus.

[Explanation of symbols]

1 ... Holding plate, 2 ... Housing, 2a ... Development chamber, 3
... developing blade, 11 ... first plate portion (second surface portion), 12
... second plate portion (second surface portion), 13 ... inner corner, 14 ... mounting corner portion, 15 ... outer corner, 16 ... space, 20 ... holding plate pressing member, 50 ... collar (movable means), 51 ... screw Through hole (movable means), 60 ... protrusion, S1 ... screw.

Claims (6)

[Claims] 1. A developing roller housed in a housing provided in a housing so as to face an image carrier such as a photosensitive drum, and the developing roller in the housing via a holding plate made of a material different from that of the housing. A developing blade fixed in parallel with the roll and abutting on the developing roll with a predetermined abutting pressure;
A long plate member having a cross-sectional shape in which the surface portions are opened at a predetermined angle to each other, the inner corner side of which is directed toward a mounting corner portion formed in the housing, and the outer corner side is provided with a space, In a developing device in which both longitudinal ends of a plate portion are fixed to the mounting corners, the housing is provided with a holding plate pressing member that presses a surface of the holding plate on the outer corner side. Development device. 2. The developing device according to claim 1, wherein the holding plate pressing member is detachably attached to the housing at one location or a plurality of locations along a longitudinal direction of the holding plate. . 3. The developing device according to claim 1, wherein the holding plate pressing member has elasticity and elastically presses the surface of the holding plate on the outer corner side. 4. The developing device according to claim 1, wherein the holding plate pressing member is formed integrally with the housing. 5. A developing roll housed in a housing provided in a housing so as to face an image bearing member such as a photosensitive drum, and the developing roller in the housing via a holding plate made of a material different from that of the housing. A developing blade fixed in parallel with the roll and abutting on the developing roll with a predetermined abutting pressure;
A long plate member having a cross-sectional shape in which the surface portions are opened at a predetermined angle to each other, the inner corner side of which is directed toward a mounting corner portion formed in the housing, and the outer corner side is provided with a space, In the developing device in which both ends in the longitudinal direction of the plate portion are fixed to the mounting corners by screwing screws into the mounting corners, the screws passing through the threaded holes formed in the both ends, A developing device, which is provided with a movable means for moving the holding plate relative to the housing in a longitudinal direction. 6. The projection is provided on one of the opposing surfaces of the holding plate and the mounting corner portion of the housing, and the projection is in contact with the other opposing surface. The developing device described.