JP2010032957A - Image forming unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a developer from leaking from an image forming unit. <P>SOLUTION: A sponge roller 37 provided in the image forming unit of a printer, for example, supplies developer 35a to a developing roller. An annular projecting part 41a is formed at a portion of a seal sponge 40 in contact with the end of the sponge roller 37. Therefore, a gap between the end of the sponge roller 37 and the seal sponge 40 is eliminated, thereby preventing the developer 35a from being leaked to the outside. Thus, image irregularity on paper occurring because the developer 35a is leaked to a mechanism part of the image forming unit and trouble that the leaked developer 35a drops onto the paper are prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming unit that prevents leakage of toner, which is a developer, in electrophotographic technology, and an image forming apparatus such as a printer or a copying machine using the image forming unit.

  2. Description of the Related Art Conventionally, as an image forming unit for constituting an image forming apparatus such as a printer or a copier using an electrophotographic technique, for example, those described in the following documents are known.

Japanese Utility Model Publication No. 5-17656

  The image forming unit described in Patent Document 1 is referred to as a photosensitive drum having a cylindrical surface coated with a photosensitive member, a charging roller for charging the photosensitive drum, and a light emitting diode (hereinafter referred to as “LED”) for exposing the photosensitive drum. ) A head, and a supply roller and a developing roller for carrying toner. The end of the supply roller is sealed (sealed) with a sealing member made of a plate-like elastic foam material in order to prevent toner leakage.

  However, in the combination of the supply roller and the seal member in the conventional image forming unit, the toner enters from the gap between the end portion of the supply roller and the seal material, and the toner leaks into the mechanism portion of the image forming unit. There are problems such as uneven image formation on the top, and leaked toner falling on the paper.

  An image forming unit according to the present invention includes an image carrier, a charging member that charges the image carrier, and an exposure device that exposes the image carrier, and a developer carrier that carries a developer. And a seal member that is pressed against the developer carrier and seals the developer so as to face the end of the developer carrier, and the end of the developer carrier at the press-contacted portion. An annular pressing portion (for example, an annular convex portion or an annular concave portion) is formed in the end portion of the developer carrying member and / or the seal member in the vicinity of the outer peripheral edge.

  The image forming apparatus of the present invention includes the image forming unit.

  According to the present invention, since the annular pressing portion is formed on the opposite surface side between the seal member and the end of the developer carrier, there is no gap between the end of the developer carrier and the seal member, The developer can be prevented from leaking outside. As a result, it is possible to prevent the unevenness of the image on the recording medium due to the leakage of the developer to the mechanical part of the image forming unit and the problem that the leaked developer falls on the recording medium.

  The best mode for carrying out the invention will become apparent from the following description of the preferred embodiments when read in conjunction with the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Example 1)
FIG. 2 is a schematic configuration diagram showing the image forming apparatus in Embodiment 1 of the present invention, and FIG. 3 is a schematic configuration diagram showing the periphery of the image forming unit in FIG.

  In general, in an image forming apparatus using an image forming unit which is a developing device for forming an image, for example, a negative charge is stored and charged on the surface of a photosensitive drum by a charging roller, and a printing pattern is formed by an LED head. The light corresponding to is exposed. The charge on the photosensitive drum is about 0 volts because the charge disappears only in the portion irradiated with light. The negatively charged toner is supplied to the photosensitive drum by the supply roller and the developing roller, and the toner adheres only to the exposed portion and is developed. The unexposed portion remains negative and repels the negative toner, so that the toner does not adhere. Next, a transfer unit provided outside the image forming unit applies a positive charge to the toner on the photosensitive drum from the back side of the paper, and the negative potential toner is attracted from the back side of the paper to the paper. Transcribed. Thereafter, the toner is melted by heat by a heat roller provided outside the image forming unit and fixed (printed) on the paper.

Hereinafter, the image forming apparatus of Example 1 will be described in detail.
The image forming apparatus shown in FIG. 2 is, for example, an electrophotographic color printer, and the lower frame (lower frame) 1 is provided with a paper transport path 10 for transporting a recording medium (for example, paper). The paper transport path 10 includes paper feed rollers 11 and 12 and discharge rollers 13 and 14, and a paper feed cassette 21 for storing paper 20 and a stacker 22 are provided at the end of the paper transport path 10. . In the paper transport path 10, a paper feeding unit 23 that feeds the paper 20 from the paper feeding cassette 21, a transfer belt unit 24, and a fixing unit 25 are provided. The transfer belt unit 24 includes a transfer roller 24b that rotates and moves the transfer belt 24a, a transfer roller 24c, and the like. The sheet 20 fed by the sheet feeding unit 23 is attached to the transfer belt 24a by an electrostatic effect and fixed. 25. The fixing unit 25 melts the developer 35a, which is toner, with heat and presses it to fix it on the paper 20.

  On the transfer belt unit 24, a plurality of image forming units 30 (for example, an image forming unit 30K for forming black, an image forming unit 30Y for forming yellow, and a magenta forming unit) which are developing devices for forming color images. An image forming unit 30M and an image forming unit 30C for forming cyan are arranged.

  Each image forming unit 30 shown in FIG. 3 has a base frame 31, and an image carrier (for example, a photosensitive drum) 32 that can be rotated by driving a motor or the like (not shown) is provided in the base frame 31. Yes. The photosensitive drum 32 accumulates charges on the surface and can remove charges on the surface by exposure. A charging member (for example, a charging roller) 33 contacts the surface of the photosensitive drum 32 at a constant pressure. ing. The charging roller 33 is a roller that can apply a predetermined charge to the surface of the photosensitive drum 32 and rotates in the same direction as the photosensitive drum 32. An exposure device (for example, an LED head) 34 for removing charges accumulated by the charging roller 33 is provided above the photosensitive drum 32.

  On the upper part of the base frame 31, for example, a developer supply device 35 which is a toner cartridge is provided. The developer supply device 35 is a device for storing the developer 35 a and transporting the developer 35 a into the base frame 31. Further, inside the base frame 31, a developing roller 36 for developing the developer 35a supplied from the developer supply device 35 onto the photosensitive drum 32, and development for supplying the developer 35a to the developing roller 36 are provided. An agent carrier (for example, a sponge roller as a supply roller) 37 and a developing blade 38 for regulating the developer 35a on the developing roller 36 to a certain thickness are provided. The photosensitive drum 32 is in contact with a constant pressure.

  A cleaning unit 39 is provided in the vicinity of the charging roller 33. The cleaning unit 39 is a device that removes the developer 35a remaining on the surface of the photosensitive drum 32 with the cleaning blade 39a. A transfer belt 24a and a transfer roller 24c are disposed below the photosensitive drum 32. The developer 35 a developed on the surface of the photosensitive drum 32 is transferred onto the paper 20 by the transfer belt 24 a and the transfer roller 24 c, and a developer image 20 a is formed on the paper 20.

  4 is a perspective view showing a peripheral portion of the sponge roller 37 in FIGS. 2 and 3, and FIG. 5 is a front view showing the sponge roller 37 in FIG.

  The sponge roller 37 has a shaft portion 37a whose both ends are rotatably attached to the base frame 31, and a cylindrical sponge portion 37b formed of a sponge material is mounted around the shaft 37a. . Various materials can be used as the sponge material of the sponge portion 37a. For example, silicon sponge (Asker FP, product having a hardness of about 45 to 55 degrees) made by foam molding of silicon rubber is preferable. A substantially plate-like seal member (for example, a seal sponge) 40 that contacts these is fixed to the base frame 31 on the outer peripheral surface 37Z at both ends of the shaft portion 37a and the both end surfaces 37Y of the sponge portion 37b.

  The seal sponge 40 prevents the developer 35a from leaking from the end of the sponge roller 37 to the outside, and can be formed of various sponge materials. As the sponge material of the seal sponge 40, a sponge material having a hardness higher than that of the sponge portion 37b, for example, a urethane sponge made by foaming polyurethane (Asker FP, product having a hardness of about 75 to 85 degrees) is preferable. A plate 42 is disposed on the outer portion of the seal sponge 40, and the plate 42 is configured to support the axial pressing force applied to the seal sponge 40. The material of the plate 42 can be formed of various materials such as a resin such as HI-PS and ABS.

  6 (a1), (b1), (c1), (a2), (b2), and (c2) are configuration diagrams showing the seal sponge 40 in FIG. 4, and FIG. 6 (a1) is a comparative example. FIG. 1B is a front view of FIG. 1A1, FIG. 1C1 is a top view of the plan view of FIG. 1A1, and FIG. (B2) is a front view of FIG. (A2), and (c2) is a top view which is a plan view of FIG. (A2).

  The seal sponge 40 has a substantially inverted triangular plate shape, and an insertion hole 41 for inserting the end portion of the shaft portion 37a in the sponge roller 37 is formed in the lower portion thereof. The seal sponge 40 of the first embodiment shown in FIGS. 6 (a2) to (c2) has a sponge portion in the sponge roller 37 as compared with the conventional one shown in FIGS. 6 (a1) to (c1) which is a comparative example. An annular pressing portion (for example, a circular convex portion) 41a is formed around the insertion hole 41 facing the end surface 37Y of 37b and in contact with the end surface 37Y. The circular convex portion 41a is concentric with the center of the shaft portion 37b of the sponge roller 37, and the outer diameter of the circular convex portion 41a is substantially the same as the outer diameter of the end surface 37Y. The height α of the circular convex portion 41a is preferably about 0.1 mm to 3 mm, for example, and in the case of the first embodiment, the height α is about 1 mm.

  FIGS. 1A and 1B are cross-sectional views showing the attachment state of the seal sponge 40 and the sponge roller 37 in FIG. 4 according to the first embodiment of the present invention. FIG. The cross-sectional view and FIG. 4B are enlarged views of the portion X in FIG. FIGS. 7A and 7B are cross-sectional views showing a state in which a conventional seal sponge 40 and a sponge roller 37, which are comparative examples with respect to FIGS. 1A and 1B, are attached, and FIG. Sectional drawing which shows the whole state, and the figure (b) are the enlarged views of the X section in the figure (a).

  In the contact state between the sponge roller 37 and the seal sponge 40, the end surface 37Y of the sponge portion 37a is pushed and elastically deformed by the convex portion 41a of the seal sponge 40, and the sponge roller 37 and the seal sponge 40 are pressed by the elastic contact. The pressure contact is ensured, and the developer 35a is prevented from leaking from the end surface 37Y of the sponge roller 37 to the outside. The axial pressing force applied to the seal sponge 40 is supported by the plate 42.

(Modification of Example 1)
FIG. 8 shows a first modification of the first embodiment, and is an enlarged cross-sectional view showing a mounting state of the seal sponge 40 and the sponge roller 37 corresponding to FIG.

  As a first modification of the seal sponge 40 in the first embodiment, a seal sponge 40 having a shape as shown in FIG. 8 may be used. In the seal sponge 40 of FIG. 8, the outer diameter of the circular convex portion 41 a is smaller than the outer diameter of the end surface 37 </ b> Y of the sponge portion 37 b in the sponge roller 37 as compared with the one shown in FIG. .

  FIG. 9 shows a second modification of the seal sponge 40 in the first embodiment, and is an enlarged cross-sectional view showing a state in which the seal sponge 40 and the sponge roller 37 corresponding to FIG.

  As a second modification of the seal sponge 40 in the first embodiment, a seal sponge 40 having a shape as shown in FIG. 9 may be used. In the seal sponge 40 of FIG. 9, double circular convex portions 41a1 and 41a2 are formed around the insertion hole 41 and concentric with the center of the shaft portion 37a of the sponge roller 37, and the double convex portion 41a1. , 41a2 is provided with a gap E (for example, a separation portion in which the two protrusions 41a1 and 41a2 are separated by a predetermined distance) E.

(Operation / Function of Example 1)
The overall operation (1) of the image forming apparatus according to the first exemplary embodiment, the operation (2) of each image forming unit 30, and the operation of the seal sponge 40 and the sponge roller 37 will be described.

(1) Overall Operation of Image Forming Apparatus In FIG. 2, the paper 20 fed from the paper feed cassette 21 passes through the paper transport path 10 via the paper feed rollers 11 and 12 and the discharge rollers 13 and 14. Thereafter, the image of the developer 35a formed by each image forming unit 30 (= 30K, 30Y, 30M, 30C) is transferred onto the paper 20 by the transfer roller 24c on the transfer belt unit 24, and is fixed by the fixing unit 25. And discharged to the stacker 22.

(2) Operation of each image forming unit 30 (= 30K, 30Y, 30M, 30C) In FIG. 3, a constant charge is applied to the surface of the photosensitive drum 32 by the charging roller 33, and the surface of the photosensitive drum 32 is uniform. Is charged. Only the charge on the image portion is removed from the uniformly charged surface of the photosensitive drum 32 by the light generated from the LED head 34 to form an electrostatic latent image. A developer 35 a is supplied from a developer supply device 35 into each image forming unit 30. The supplied developer 35 a is supplied to the developing roller 36 by the sponge roller 37. The developer 35 a supplied to the developing roller 36 is regulated to a certain thickness by the developing blade 38, and the developer 35 a is developed on the electrostatic latent image formed on the surface of the photosensitive drum 32. The developer 35 a developed on the surface of the photosensitive drum 32 is transferred onto the paper 20 by the transfer belt 24 a and the transfer roller 24 c, and a developer image 20 a is formed on the paper 20.

(3) Action of Seal Sponge 40 and Sponge Roller 37 In the conventional FIG. 7 showing the comparative example, since the seal sponge 40 and the sponge roller 37 are flat with each other, a gap is likely to be formed between these end portions. From this gap, the developer 35a leaks to the outside through the end surface 37Y of the sponge portion 37b of the sponge roller 37 and the outer peripheral surface 37Z of the shaft portion 37a. However, in the first embodiment shown in FIG. 1, even if there is a gap between the seal sponge 40 and the end surface 37Y of the sponge portion 37b, the convex portion 41a of the seal sponge 40 makes contact with the sponge roller 37 (close state). ) Is maintained, it is possible to prevent the developer 35a from being blocked by the protrusion 41a and leaking.

  In the first embodiment, the seal sponge 40 having the shape shown in the first modification of FIG. 8 may be used. The seal sponge 40 in FIG. 8 is obtained by making the outer diameter of the circular convex portion 41a smaller than the outer diameter of the end surface 37Y of the sponge portion 37b in the sponge roller 37, as compared with that shown in FIG. When the outer diameter of the circular convex portion 41a is reduced, the area of the contact portion between the seal sponge 40 and the sponge roller 37 is reduced. By reducing the pressure contact surface, the frictional force that the sponge roller 37 receives due to the pressure contact of the seal sponge 40 is reduced, and the driving load of the sponge roller 37 is reduced.

  Moreover, you may use the seal sponge 40 of the shape shown by the modification 2 of FIG. In FIG. 9, circular convex portions 41a1 and 41a2 on the seal sponge 40 are formed concentrically in a double manner, and a separating portion E is provided between the double convex portions 41al and 41a2. When the sponge roller 37 and the seal sponge 40 are in contact with each other, there are two portions of the sponge roller 37 where the end surface 37Y of the sponge portion 37b and the seal sponge 40 are in contact with each other, that is, the convex portions 41al and 41a2. In addition, since the separation portion E is provided between the convex portion 41al and the convex portion 41a2, and a step is formed, for example, when each image forming unit 30 is in operation, an impact due to carelessness of the user or the like is unexpectedly caused. In the event that the developer 35a gets over the convex portion 41al, the path becomes longer due to the step, so that the developer 35a that has passed over accumulates in the separation portion E and the convex portion 41a2 is pressed. Further, it is possible to prevent the developer 35a from leaking outside without passing through the outer peripheral surface 37Z of the shaft portion 37b of the sponge roller 37.

(Effect of Example 1)
According to the first embodiment, since the circular convex portion 41a or the double circular convex portions 41al and 41a2 are formed at the portion of the seal sponge 40 that contacts the end portion of the sponge roller 37, the sponge roller 37 This eliminates the gap between the end of the seal sponge 40 and the seal sponge 40, thereby preventing the developer 35a from leaking outside. As a result, it is possible to prevent the unevenness of the image on the paper 20 due to the developer 35a leaking into a mechanism (not shown) of each image forming unit 30 and the problem that the leaked developer 35a falls on the paper 20.

(Configuration of Example 2)
10A and 10B are configuration diagrams showing the sponge roller 37 and the seal sponge 40 according to the second embodiment of the present invention. FIG. 10A is a sectional view of the sponge roller 37 and FIG. b) is a partial enlarged cross-sectional view showing a state in which the seal sponge 40 and the sponge roller 37 are attached. 10 (a) and 10 (b), elements common to those in FIGS. 1 (a) and 1 (b) showing the first embodiment are denoted by common reference numerals.

  A convex portion 37c is formed from the shaft portion 37a of the sponge roller 37 toward the outer peripheral edge of the sponge portion 37b at the end portion where the sponge portion 37b of the sponge roller 37 and the seal sponge 40 are in contact with each other. The convex portion 37c of the sponge roller 37 has a shape such that there is no convex portion in the shaft portion 37a, but has an inclination that finally becomes the size of α at the outer peripheral edge portion of the sponge portion 37b.

(Modification of Example 2)
FIGS. 11A and 11B are configuration diagrams of a sponge roller 37 and a seal sponge 40 showing a first modified example with respect to FIGS. 10A and 10B of the second embodiment, and FIG. 11A is a sponge. A sectional view of the roller 37 and FIG. 11B are partially enlarged sectional views showing a state in which the seal sponge 40 and the sponge roller 37 are attached.

  As a first modification of the second embodiment, a sponge roller 37 as shown in FIGS. 11A and 11B may be used. A circular convex portion 37c concentric with the center of the shaft portion 37a of the sponge roller 37 is formed at an end portion where the sponge portion 37b of the sponge roller 37 and the seal sponge 40 are in contact with each other, and this height is α.

  FIGS. 12A and 12B are configuration diagrams of a sponge roller 37 and a seal sponge 40 showing a second modification of the second embodiment with respect to FIGS. 10A and 10B, and FIG. 12A is a sponge. A sectional view of the roller 37 and FIG. 12B are a partially enlarged sectional view showing a state in which the seal sponge 40 and the sponge roller 37 are attached.

  As a second modification of the second embodiment, a sponge roller 37 as shown in FIGS. 12A and 12B may be used. Double circular convex portions 37c1 and 37c2 concentric with the center of the shaft portion 37a of the sponge roller 37 are formed at an end portion where the sponge portion 37b of the sponge roller 37 and the seal sponge 40 are in contact with each other. There is a gap (for example, a space) F between the convex portion 37c1 on the outer peripheral side and the convex portion 37c2 on the inner peripheral side. The heights of the convex portions 37c1 and the convex portions 37c2 are both the same α. In addition, you may make the height of the convex part 37c1 and the convex part 37c2 differ.

(Operation of Example 2)
The operation of the seal sponge 40 and the sponge roller 37 in the second embodiment will be described with reference to FIGS. 10A and 10B. The sponge roller 37 has a convex portion 37c. Therefore, a pressure contact state occurs between the sponge roller 37 and the seal sponge 40 due to the convex portion 37c, and the developer 35a cannot pass therethrough, and the outer peripheral surface 37Z of the shaft portion 37a in the sponge roller 37 Can be prevented from leaking.

  In the second embodiment, the sponge roller 37 having the shape shown in the first modification of FIGS. 11A and 11B may be used. In FIGS. 11A and 11B, at the end where the sponge roller 37 and the seal sponge 40 are in contact with each other, the convex portion 37c and the seal sponge 40 are in contact with each other. Can be prevented from leaking toward the outer peripheral surface 37Z of the sponge roller 37.

  Further, the sponge roller 37 having the shape shown in the modified example 2 of FIGS. 12A and 12B may be used. 12A and 12B, the convex portion 37 c 1 and the convex portion 37 c 2 are in contact with the seal sponge 40 at the end where the sponge roller 37 and the seal sponge 40 are in contact with each other. In addition, since there is a space F between the convex portions 37cl and 37c2, for example, during the operation of each image forming unit 30, a shock due to carelessness of the user or the like is unexpectedly caused, and the developer 35a should be convex. Even if the part 37cl is overcome, the developer 35a accumulates in the space F and the pressure contact with the seal sponge 40 of the convex part 37c2 is maintained, so that the developer 35a does not pass through the outer peripheral surface 37Z of the sponge roller 37. Can be prevented from leaking.

(Effect of Example 2)
According to the second embodiment, the convex portion 37c of the sponge roller 37 or the double convex portions 37cl and 37c2 are formed at the end where the sponge portion 37b of the sponge roller 37 and the seal sponge 40 are in contact with each other. There is no gap between the end of the roller 37 and the seal sponge 40, and the effect of preventing the developer 35a from leaking to the outside is obtained. As a result, it is possible to prevent the unevenness of the image on the paper 20 due to the developer 35a leaking into a mechanism (not shown) of each image forming unit 30 and the problem that the leaked developer 35a falls on the paper 20. Further, in the second embodiment and the first and second modified examples 1 and 2, since the convex portions 37c, 37c1 and 37c2 are provided on the sponge roller 37 side, as in the first embodiment and the modified examples 1 and 2, a seal is provided. Compared to the structure in which the convex portions 41a, 41a1, and 41a2 are provided on the sponge 40 side, for example, when the sponge portion 37b is formed by using a mold for foam molding, the convex portions 37c, 37c1, and 37c2 are relatively simple. Can be formed with high accuracy.

(Configuration of Example 3)
FIGS. 13A and 13B are configuration diagrams showing the sponge roller 37 and the seal sponge 40 according to the third embodiment of the present invention. FIG. 13A is a sectional view of the sponge roller 37 and FIG. b) is a partial enlarged cross-sectional view showing a state in which the seal sponge 40 and the sponge roller 37 are attached. 13 (a) and 13 (b), FIGS. 1 (a), (b), FIG. 8, FIG. 9, and FIG. 10 (a), FIG. Elements common to elements in 12 (a) and (b) are denoted by common reference numerals.

  The sponge roller 37 used in the third embodiment is the same as that used in FIGS. 10A and 10B, and the seal sponge 40 is the same as that used in FIG.

(Modification of Example 3)
FIGS. 14A and 14B are configuration diagrams of the sponge roller 37 and the seal sponge 40 showing a first modification of the third embodiment with respect to FIGS. 13A and 13B, and FIG. 14A is a sponge. A sectional view of the roller 37 and FIG. 14B are partially enlarged sectional views showing a state in which the seal sponge 40 and the sponge roller 37 are attached.

  As a first modification of the third embodiment, a combination of the same sponge roller 37 used in FIGS. 12A and 12B and the same seal sponge 40 used in FIG. 10 may be used.

  FIGS. 15A and 15B are configuration diagrams of a sponge roller 37 and a seal sponge 40 showing a second modification of the third embodiment with respect to FIGS. 13A and 13B, and FIG. 15A is a sponge. A sectional view of the roller 37 and FIG. 15B are partially enlarged sectional views showing a state in which the seal sponge 40 and the sponge roller 37 are attached.

  As a second modification of the third embodiment, a combination of the same sponge roller 37 used in FIGS. 11A and 11B and the same seal sponge 40 used in FIG. 9 may be used.

(Operation of Example 3)
The operation of the seal sponge 40 and the sponge roller 37 in the third embodiment will be described with reference to FIGS. 13 (a) and 13 (b). Since the convex portion 37c of the sponge roller 37 and the convex portion 41a of the seal sponge 40 are pressed against each other at the end of the sponge roller 37 that contacts the seal sponge 40, the convex portion 37c of the sponge roller 37 and the convex portion of the seal sponge 40 are The pressure contact state with the portion 41a is maintained, and the developer 35a cannot pass through the pressure contact portion and can be prevented from leaking toward the outer peripheral surface 37Z of the sponge roller 37.

  In the third embodiment, the sponge roller 37 and the seal sponge 40 having the shape shown in the first modification of FIGS. 14A and 14B may be used. Since the convex portions 37c1 and 37c2 of the sponge roller 37 and the convex portion 41a of the seal sponge 40 are pressed against each other at the end of the sponge roller 37 that contacts the seal sponge 40, the developer 35a cannot pass through the press-contact portion. Further, leakage toward the outer peripheral surface 37Z of the sponge roller 37 can be prevented. In addition, the sponge roller 37 has two convex portions 37c1 and 37c2, and the convex portion 41a of the seal sponge 40 is positioned between the two convex portions 37c1 and 37c2. In this way, by alternately arranging the convex portions of the sponge roller 37 and the seal sponge 40, the length in which the sponge roller 37 and the seal sponge 40 are in pressure contact with each other is increased, and the developer 35a is more closely connected to the outer peripheral surface 37Z. It will be difficult to leak.

  Further, the sponge roller 37 and the seal sponge 40 having the shape shown in the modified example 2 of FIGS. 15A and 15B may be used. Since the convex portion 37c of the sponge roller 37 and the convex portions 41al and 41a2 of the seal sponge 40 are pressed against each other at the end portion of the sponge roller 37 that contacts the seal sponge 40, the developer 35a cannot pass through the press-contact portion. Further, leakage toward the outer peripheral surface 37Z of the sponge roller 37 can be prevented. In addition, as in the case of FIGS. 14A and 14B, the length of the pressure contact between the sponge roller 37 and the seal sponge 40 by alternately arranging the convex portions of the sponge roller 37 and the seal sponge 40. And the developer 35a is less likely to leak toward the outer peripheral surface 37Z.

(Effect of Example 3)
According to the third embodiment, the convex portion 37c of the sponge roller 37 or the two convex portions 37cl and 37c2 are formed at the end where the sponge portion 37b of the sponge roller 37 contacts the seal sponge 40, and the seal sponge 40 , Or the two convex portions 41al and 41a2 are formed, the gap between the end of the sponge roller 37 and the seal sponge 40 is eliminated, and the developer 35a does not pass through the outer peripheral surface 37Z of the sponge roller 37 and is externally provided. The effect that it can prevent leaking is obtained. Further, the convex portions 37c or the two convex portions 37cl and 37c2 of the sponge roller 37 and the convex portions 41a or the two convex portions 41al and 41a2 of the seal sponge 40 are alternately arranged, so that the sponge roller 37 and the seal sponge are provided. The pressure contact length of 40 becomes longer, and the effect that the developer 35a is more difficult to leak is also obtained. As a result, it is possible to prevent the unevenness of the image on the paper 20 due to the developer 35a leaking into a mechanism (not shown) of each image forming unit 30 and the problem that the leaked developer 35a falls on the paper 20.

  16 (a1), (b1), (a2), and (b2) are partial configuration diagrams showing the seal sponge 40 and the sponge roller 37 in the fourth embodiment of the present invention, and FIG. The partial cross-sectional view of the sponge 40 and the sponge roller 37, (b1) is a diagram showing the pressure contact state between the seal sponge 40 and the sponge roller 37 in (a1), (a2) is a seal sponge of another shape 40 and a partial cross-sectional view of the sponge roller 37, and FIG. 8B2 are views showing a pressure contact state between the seal sponge 40 and the sponge roller 37 in FIG. In these FIG. 16 (a1), (b1), (a2), (b2), the same code | symbol is attached | subjected to the element in the drawing which shows Examples 1-3 and this modification 1,2. Has been.

  16 (a1) and 16 (b1), an annular (for example, circular) concave portion 37d is formed on the end surface 37Y of the sponge portion 37b of the sponge roller 37, and an annular portion facing the concave portion 37d is formed on the seal sponge 40 side. A pressing portion (for example, a circular convex portion) 41a is formed. The depth of the cross section of the concave portion 37d is greater than the height of the cross section of the convex portion 41a, and the width of the cross section of the concave portion 37d is smaller than the width of the cross section of the convex portion 41a. Therefore, in a state where the end surface 37Y of the sponge portion 37b and the seal sponge 40 are in pressure contact, the convex portion 41a is press-fitted so as to push the concave portion 37d, and a space G is generated at the bottom of the concave portion 37d.

  Therefore, the press contact state is maintained at the contact portion between the convex portion 41a and the concave portion 37d, so that the developer 35a can be prevented from leaking toward the outer peripheral surface 37Z of the sponge roller 37. Moreover, since there is a space G at the bottom of the concave portion 37d, even if the developer 35a passes through the contact portion, the developer 35a can be prevented from collecting in the space G and leaking to the outside. .

  16 (a2) and 16 (b2), an annular pressing portion (for example, a circular convex portion 37c and a concave portion 37d) is formed on the end surface 37Y of the sponge portion 37b of the sponge roller 37, and is opposed to the concave portion 37d. An annular pressing portion (for example, a circular convex portion 41a) is formed on the seal sponge 40 side. The depth of the cross section of the concave portion 37d is smaller than the height of the cross section of the convex portion 41a, and the width of the cross section of the concave portion 37d is substantially the same as the width of the cross section of the convex portion 41a. Therefore, in a state where the end surface 37Y of the sponge portion 37b and the seal sponge 40 are in pressure contact with each other, the top portion of the convex portion 41a is press-fitted while pressing the bottom of the concave portion 37d, and the convex portion 37c presses the surface of the seal sponge 40. It is press-fitted in the state.

  For this reason, the press contact state is maintained at the two locations of the contact portion of the concave portion 37d and the convex portion 41a and the contact portion of the convex portion 37c and the seal sponge surface, so that the exposure of the developer 35 to the outside can be accurately prevented. it can.

  As a modification, in FIGS. 16 (a1) and (b1), the convex portion 41a is formed on the sponge portion 37b side and the concave portion 37d is formed on the seal sponge 40 side, or FIG. 16 (a2), In (b2), when the convex portion 41a is formed on the sponge portion 37b side and the convex portion 37c and the concave portion 37d are formed on the seal sponge 40 side, substantially the same effect as described above can be obtained.

(Other variations of Examples 1 to 4)
The present invention is not limited to the above-described embodiments and modifications, and various other usage forms and modifications are possible. For example, the following forms (A) to (D) are available as usage forms and modifications.

  (A) In Examples 1 to 4, the convex portions 37c, 37c1, 37c2, 41a, 41a1, and 41a2 may be impregnated with resin. As the resin, for example, polyacetal resin (POM) is preferable, and other resins such as polyamide resin and polypropylene resin may be used. By adopting such a configuration, the convex portions 37c, 37c1, 37c2, 41a, 41a1, and 41a2 impregnated with resin can withstand compression even when pressed from the other sponge portion 37b, so that the convex portions are formed high. It is not necessary to increase the processing accuracy of the convex portion. Furthermore, according to such a configuration, since the convex portions 37c, 37c1, 37c2, 41a, 41a1, and 41a2 impregnated with the resin and the sponge are rubbed, the friction can be made lower than the friction between the sponges. .

  (B) The circular convex portions 37c, 37c1, 37c2, 41a, 41a1, 41a2, and the concave portion 37d are other annular shapes such as an ellipse and a polygon having an outer diameter smaller than the outer diameter of the end surface 37Y in the sponge portion 37b. You may change to the press part.

  (C) The present invention can also be applied to a developer carrier including a supply roller other than the sponge roller 37. For example, the present invention can also be applied to a seal member or the like on a drive gear shaft of a belt that conveys the developer 35a scraped off in contact with the photosensitive drum 32 to the developer recovery chamber.

  (D) In the embodiments, the image forming apparatus has been described as a printer. However, the present invention can also be applied to an image forming unit or the like mounted on a facsimile machine, a copier, and a device having them in combination.

It is sectional drawing which shows the attachment state of the seal sponge and sponge roller in FIG. 4 in Example 1 of this invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first exemplary embodiment of the present invention. FIG. 3 is a schematic configuration diagram showing the periphery of an image forming unit in FIG. 2. It is a perspective view which shows the peripheral part of the sponge roller in FIG.2 and FIG.3. It is a front view which shows the sponge roller in FIG. It is a block diagram which shows the seal | sticker sponge in FIG. It is sectional drawing of the attachment state of the seal sponge and sponge roller which show the comparative example with respect to Fig.1 (a), (b). FIG. 7 is a cross-sectional view illustrating a first modified example of the first embodiment and illustrating an attached state of a seal sponge and a sponge roller corresponding to FIG. FIG. 9 is a cross-sectional view illustrating a modified example 2 of the seal sponge according to the first embodiment and illustrating a state in which the seal sponge and the sponge roller corresponding to FIG. 1B are attached. It is a block diagram which shows the sponge roller and seal sponge in Example 2 of this invention. It is a block diagram of the sponge roller and seal sponge which show the modification 1 with respect to FIG. 10 (a), (b) of Example 2. FIG. It is a block diagram of the sponge roller and seal sponge which show the modification 2 with respect to FIG. 10 (a), (b) of Example 2. FIG. It is a block diagram which shows the sponge roller and seal sponge in Example 3 of this invention. It is a block diagram of the sponge roller and seal sponge which show the modification 1 with respect to FIG. 13 (a), (b) of Example 3. FIG. It is a block diagram of the sponge roller and seal sponge which show the modification 2 with respect to FIG. 13 (a), (b) of Example 3. FIG. It is a partial block diagram which shows the seal sponge and sponge roller in Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Paper conveyance path 24 Transfer belt unit 25 Fixing part 30,30K, 30Y, 30M, 30C Image formation unit 32 Photosensitive drum 33 Charging roller 34 LED head 35a Developer 36 Developing roller 37 Sponge roller 37c, 37c1, 37c2 Convex part 37d Concave part 40 Seal sponge 41a, 41a1, 41a2 Convex part

Claims (15)

In an image forming unit having an image carrier, a charging member that charges the image carrier, and an exposure device that exposes the image carrier,
A developer carrying member carrying the developer;
A seal member that is pressed against the developer carrier facing the end of the developer carrier and seals the developer;
An annular pressing portion is formed in the end portion of the developer carrying member and / or the seal member in the vicinity of the outer peripheral edge of the end portion of the developer carrying member at the press contact portion. Image forming unit.   The image according to claim 1, wherein the end portion of the developer carrying member and / or the annular pressing portion formed on the seal member is formed concentrically with respect to the developer carrying member. Forming unit.   The image forming unit according to claim 1, wherein the annular pressing portion is an annular convex portion.   The image forming unit according to claim 1, wherein the annular pressing portion is an annular recess. The annular projection is
A plurality of concentric with the developer carrier,
The image forming unit according to claim 3, wherein a spacing portion is provided between the plurality of annular convex portions. The annular projection is
A plurality of concentric with the developer carrier,
4. The image forming unit according to claim 3, wherein, when the seal member and the developer carrier are combined, a gap is formed between the plurality of annular convex portions. In the annular recess,
5. The image forming unit according to claim 4, wherein the annular convex portion formed on the end portion of the developer carrying member and / or the seal member is press-fitted. In the spacing between the plurality of annular convex portions and convex portions,
6. The image forming unit according to claim 5, wherein the annular convex portion formed on the end portion of the developer carrying member and / or the seal member is press-fitted. The ring is
The image forming unit according to claim 1, wherein the image forming unit is circular. The ring is
The image forming apparatus according to any one of claims 1 to 8, wherein the outer diameter is an ellipse or a polygon, and a maximum dimension of the outer diameter is smaller than an outer diameter dimension at an end portion of the developer carrying member. unit. The developer carrier and the seal member are
The image forming unit according to claim 3, wherein the image forming unit is formed using a sponge material. The sponge material forming the developer carrier is a silicon sponge,
12. The image forming unit according to claim 11, wherein the sponge material forming the seal member is a urethane sponge having a hardness higher than that of the silicon sponge. In the annular convex part,
The image forming unit according to claim 11, wherein the image forming unit is impregnated with a resin. The developer carrier is
The image forming unit according to claim 1, wherein the image forming unit is a supply roller that carries the developer.   An image forming apparatus comprising the image forming unit according to claim 1.

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