JP4952497B2 - Development device - Google Patents

Description

  The present invention relates to a developing device used in an electrophotographic image forming apparatus. More specifically, the present invention relates to a developing device that prevents leakage of toner from the housing of the developing device to the outside.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus has a developing device for developing toner by supplying toner to a photoreceptor. The housing of the developing device contains toner. An opening is provided in the housing, and the developing roller faces the photoconductor through the opening. Therefore, in order to prevent leakage of toner from the periphery of the developing roller at the opening, a sealing material or the like is provided around the developing roller. For example, along the axial direction of the developing roller, a neutralization sheet is provided on the downstream side of the rotation of the developing roller, and a regulating blade is provided on the upstream side, each of which plays a role of preventing toner leakage from that location. There is a developing device.

  Furthermore, there is a developing device in which a seal material is provided in the vicinity of both ends in order to prevent toner leakage from both ends in the axial direction of the developing roller. For example, there is a case where an end seal is provided at a portion of the housing that faces the end portion in the axial direction of the developing roller. Further, in order to ensure the press-contact between the end seal and the developing roller, there is also a type in which a urethane foam seal is compressed on the back side of the end seal. As an example of the configuration of the end seal, there is one in which a tape made of fluororesin is attached to a part of the base of the PET film at an angle with respect to the rotation direction of the roller. Thus, the end portion of the fluororesin tape scrapes off the toner from the surface of the developing roller.

  Further, for example, Patent Document 1 discloses a developing device in which a first seal, a second seal, a third seal, and the like are provided at an end portion of a developing roller. In the apparatus of this document, toner leakage is prevented by the first seal and the third seal. In addition, the second seal is made of a thermoplastic elastomer and an oblique ridge is provided to sweep the toner to the center.

Further, for example, Patent Document 2 discloses a seal structure in which a seal member is formed by printing on a sheet material that covers the outer peripheral surface of the end portion of the developing roller. In the seal structure of this document, the convex pattern seal member is formed in an oblique direction with respect to the axis of the roller. According to the technique of this document, since the seal member is in contact with the outer periphery of the developing roller, it is said that leakage of toner to the outside can be prevented.
JP 7-134494 A JP 2000-170919 A

  However, when a tape made of fluororesin is used, the pressure contact force between the developing roller and the tape cannot be made so strong. Therefore, there has been a problem that when the amount of toner exceeding a certain amount reaches the portion of the tape, the leakage of the toner cannot be completely prevented. In addition, when the rotation of the developing roller is high, there is a problem that the tape may be scraped off or peeled off due to temperature rise.

  Further, the developing device described in Patent Document 1 has a rather complicated configuration such that a plurality of seals of different materials are stacked on each other. For this reason, there is a problem that it is difficult to manage the shape and size of each seal, the position where the seal is applied, and the like.

  In addition, for reasons such as an arrangement relationship with the photoconductor in the image forming apparatus, a seal member provided at an end portion in the axial direction of the developing roller may be arranged slightly below the developing roller. In such a case, even if a convex pattern is formed as described in Patent Document 2, the toner scraped off by the pattern may accumulate on the seal member. In that case, there is a problem that if the amount of toner accumulated in the seal member increases, the toner may leak to the outside.

  The present invention has been made to solve the problems of the conventional developing device described above. That is, the problem is that a simple configuration prevents toner leakage from the vicinity of the end portion in the axial direction of the developing roller in the opening portion of the housing, and draws the toner toward the central portion in the axial direction. An object of the present invention is to provide a developing device that makes it possible.

  In order to solve this problem, a developing device according to the present invention includes a housing that contains a developer therein, and is rotatably supported by the housing, and is partially exposed from the housing. A developing device having a developing roller for developing a latent image on the carrier, wherein the housing is formed with a curved surface portion facing the axial end of the cylindrical surface of the developing roller at an interval; A flexible sealing material that partially contacts the cylindrical surface of the developing roller is attached to the curved surface portion. The sealing material includes a wall portion that contacts the cylindrical surface of the developing roller in an arc shape, and a wall portion. On the other hand, a crest provided continuously from the wall on the axially central side of the developing roller and spirally contacts the cylindrical surface of the developing roller, and on the axially central side of the developing roller from the wall and other than the crest Position of the developing roller A valley portion that is not in contact with the column surface is formed, and the direction of the spiral inclination of the peak portion is a direction that becomes a downstream side in the rotation direction of the developing roller as it approaches the center in the axial direction of the developing roller. The surface facing the cylindrical surface of the developing roller is farther from the cylindrical surface of the developing roller as it approaches the center in the axial direction of the developing roller.

  According to the developing device of the present invention, the seal material attached to the curved surface portion is in partial contact with the axial end portion of the developing roller. The wall of the sealing material prevents the toner from leaking to the outside in the axial direction of the developing roller. Furthermore, the sealing material is formed with peaks and valleys. Since the crest portion is inclined toward the downstream side in the rotation direction of the developing roller as it approaches the center in the axial direction of the developing roller, the contact portion between the crest portion and the developing roller becomes the axis along with the rotation of the developing roller. Approach the center of the direction. As a result, the toner adhering to the developing roller is sent to the center in the axial direction. Further, the closer the bottom of the valley portion is to the axial center of the developing roller, the farther from the cylindrical surface of the developing roller, the more efficiently the toner is sent to the axial center side. Accordingly, a developing device capable of reliably preventing toner leakage from the vicinity of the axial end of the developing roller in the opening of the housing with a simple configuration and bringing the toner toward the central portion in the axial direction. It has become.

Furthermore, in the present invention, it is desirable that the curved surface portion is a cylindrical surface coaxial with the cylindrical surface of the developing roller, and the thickness of the seal material in the valley portion becomes thinner as it approaches the center in the axial direction of the developing roller.
In this case, with a simple configuration, the valley of the seal material can be separated from the cylindrical surface of the developing roller as it approaches the center in the axial direction of the developing roller.

Furthermore, in the present invention, it is desirable that the curved surface portion is a conical surface coaxial with the cylindrical surface of the developing roller.
Even in such a case, with a simple configuration, the valley of the sealing material can be separated from the cylindrical surface of the developing roller as it approaches the center in the axial direction of the developing roller.

Furthermore, in the present invention, it is desirable that the sealing material be attached in a compressed state in the thickness direction between the housing and the developing roller.
In this case, even if the sealing member is provided on the conical surface, the peak portion can be surely brought into contact with the cylindrical surface of the developing roller.

  According to the developing device of the present invention, toner leakage from the vicinity of the axial end of the developing roller in the housing opening can be reliably prevented and the toner can be moved to the axial central portion with a simple configuration. Can be sent.

"First form"
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a developing device that is used in an electrophotographic image forming apparatus and develops an electrostatic latent image on a photoreceptor.

  As shown in FIG. 1, the developing device 1 according to this embodiment has a housing 11 and is unitized. The housing 11 is formed with an opening 11a on the front side in the figure, from which a part of the developing roller 12 is exposed. When the developing device 1 is attached to the image forming apparatus, the exposed portion of the developing roller 12 is disposed to face the photoconductor. The roller shaft portion 12 a of the developing roller 12 is supported so as to be rotatable with respect to the housing 11. The roller body 12b of the developing roller 12 has a larger diameter than the roller shaft 12a. The outer peripheral surface of the roller body portion 12b is a cylindrical surface. In addition, toner is accommodated in the housing 11. In this embodiment, non-magnetic one-component toner is used.

  At the time of development processing, the developing roller 12 is rotated so that the front surface in FIG. 1 is directed from bottom to top. A regulating blade 13 is in contact with the lower side of the developing roller 12 in the figure. Although not visible in FIG. 1, a charge eliminating sheet 14 is provided on the upper side of the developing roller 12 in the drawing (see FIG. 3). The regulation blade 13 and the charge removal sheet 14 are attached to the housing 11, and one end thereof is in contact with the developing roller 12. Both the regulation blade 13 and the charge removal sheet 14 are in contact with the developing roller 12 in the lateral direction in FIG. As a result, the leakage of toner from the housing 11 at the top and bottom of the developing roller 12 in FIG. 1 is prevented.

  Next, FIG. 2 shows an axial end portion of the housing 11 when the developing roller 12 is not attached. FIG. 2 shows the right end in FIG. The bearing 15 rotatably supports the roller shaft portion 12a of the developing roller 12. A curved surface portion 16 having an inner diameter larger than that of the bearing 15 is formed on the left side of the bearing 15 in the drawing. The inner diameter of the curved surface portion 16 is a size that does not contact the roller body portion 12 b of the developing roller 12 with the developing roller 12 attached to the housing 11. That is, the curved surface portion 16 is a cylindrical surface that faces the cylindrical surface of the developing roller 12 with an interval. A side seal 21 is provided on the left side of the curved surface portion 16 in the figure.

  FIG. 3 shows a cross section of a portion corresponding to the curved surface portion 16 of FIG. As shown in FIG. 3, side seals 21 are attached along the curved surface portion 16. The upper surface of the side seal 21 in the drawing is in contact with the outer peripheral surface of the developing roller 12. The side seal 21 is formed of a thermoplastic elastomer that is a flexible material. The side seal 21 has the shape shown in FIGS. 4 and 5 when not attached to the curved surface portion 16. In other words, the outline as a whole is a rectangular parallelepiped. Here, FIG. 5 is a view of the side seal 21 of FIG. 4 as viewed from the right front side in the drawing. The surface appearing in FIG. 5 is arranged on the upper side in FIG. 3 and contacts the cylindrical surface of the developing roller 12.

  A plurality of peak portions 21a and valley portions 21b are alternately formed on the side seal 21 on the side that contacts the developing roller 12 (the right front side in FIG. 4). And the surface (bottom surface 21c: the left back surface in FIG. 4) of the side seal 21 in the side which contacts the curved surface part 16 is a plane. Further, a surface (side surface 21d: right rear surface in FIG. 4) disposed on the end side in the axial direction of the developing roller 12 is also a flat surface, and is provided continuously with each mountain portion 21a along the side surface 21d. A wall portion 21e is formed.

  In this embodiment, the bottom surface 21c of the side seal 21 is attached to the curved surface portion 16 by a double-sided tape or an adhesive. Thereby, as shown in FIG. 3, the side seal 21 is bent and attached to the shape along the curved surface portion 16 as a whole. Alternatively, the side seal 21 may be fixed by a positioning member or the like so as to be in this arrangement. Thereby, the bottom surface 21 c becomes a cylindrical surface along the curved surface portion 16.

  As shown in FIG. 4, each peak portion 21a and wall portion 21e of the side seal 21 are formed at a common height from the bottom surface 21c. The height of the peak portion 21a from the bottom surface 21c is equal to or greater than the distance between the curved surface portion 16 and the roller body portion 12b. Therefore, by attaching the bottom surface 21 c to the curved surface portion 16, all the crest portions 21 a and the wall portions 21 e come into contact with the cylindrical surface of the developing roller 12. That is, the wall 21 e is arcuate and contacts the cylindrical surface of the developing roller 12.

  What can be seen in FIG. 3 is a side surface 21d of the side seal 21, and the wall portion 21e closes this range along the side surface 21d. Therefore, the leakage of toner to the end of the developing roller 12 in the axial direction is prevented at the side seal 21. In addition, when the height of the peak part 21a is larger than the space | interval of the curved surface part 16 and the roller body part 12b, the side seal 21 is compressed and attached between them.

  On the other hand, the valley bottom surface 21f of each valley portion 21b of the side seal 21 is not parallel to the bottom surface 21c. The valley bottom surface 21f is a slope that goes from the front to the back as it goes from right to left in FIG. Therefore, the depth of the valley is shallow in the region A on the right side in FIG. 5 and deeper in the region B on the left side. When the side seal 21 is attached to the curved surface portion 16, each valley bottom surface 21f becomes closer to the center side from the end in the axial direction of the developing roller 12 as shown in the axial cross section in FIG. It is far from the cylindrical surface. In this way, the thickness of each valley portion 21b of the side seal 21 is formed such that the end side thickness R arranged on the right side in FIG. 6 is larger than the center side thickness L arranged on the left side. ing. In FIG. 6, a small circle indicates an example of toner particles T.

  Next, returning to FIG. 5, when the side seal 21 is viewed in plan, each peak portion 21 a is formed to be inclined downward to the left. When this is attached to the curved surface portion 16, each peak portion 21a is short but spiral. Further, as shown by an arrow in FIG. 3, the developing roller 12 is rotated clockwise in the drawing during the developing process. That is, the developing roller 12 is rotated in a direction in which the developing roller 12 contacts the surface of the side seal 21 shown in FIG. That is, the direction of the spiral inclination of the peak portion 21a is closer to the downstream side in the rotation direction of the developing roller 12 as it approaches the center of the developing roller 12 in the axial direction.

  In the developing device 1 of the present embodiment, toner is carried on the outer surface of the roller body 12b of the developing roller 12 in the housing 11 during the developing process. In the opening 11a of the housing 11, the developing roller 12 carrying the toner develops the latent image on the photoreceptor. At this time, the side seals 21 are in contact with both end portions of the developing roller 12 in the axial direction. The wall 21e prevents the toner from leaking outward in the axial direction.

  Further, the toner adhering to the outer surface of the roller body portion 12b is scraped off by the peak portion 21a. Furthermore, the end surface of the surface of the developing roller 12 comes into contact with the crests 21a of the side seal 21 first in the axial direction, and the center side contacts in order. Therefore, the scraped toner is sequentially sent to the center side. Furthermore, as shown in FIG. 6, the depth of the valley portion 21b is formed deeper toward the center side. Therefore, as shown by the arrows in the figure, the toner is more reliably sent to the center side.

  Since the side seal 21 of this embodiment is formed of a thermoplastic elastomer, it can be easily manufactured even if it has a mold having such a complicated shape. It is also easy to bend along the curved surface portion 16. The side seal 21 shown in FIGS. 4 and 5 is attached to the curved surface portion 16 on the right end side in FIG. And the right side (wall part 21e side) in FIG. 5 is arrange | positioned at the axial end side, and the left side (the deep side of the trough part 21b) is arrange | positioned at the center side. And what is affixed on the left end side in FIG. 1 is a shape symmetrical to this side seal 21 as seen in FIG.

  In this embodiment, as shown in FIGS. 7, 8, and 9, the shape of the bottom of the side seal may be slightly different. For example, in the side seal 23 shown in FIG. 7, the trough 23b is curved. In other words, the slope is steep near the wall, and the slope becomes gentler toward the center. Further, in the side seal 24 shown in FIG. 8, the valley portion 24b has a stepped shape with a step in the middle of the slope. Further, in the side seal 25 shown in FIG. 9, the valley portion 25 b is an inclined surface whose inclination changes in the middle. In other words, the slope near the wall is gentle, and the slope near the center is steep.

  The shape of the valley may be any shape as long as it is farther from the cylindrical surface of the developing roller 12 toward the center in the axial direction of the developing roller 12. In any case, the crests 23 a, 24 a, and 25 a are formed at the same height as the crests 21 a of the side seal 21 and are disposed so as to contact the surface of the developing roller 12.

  As described in detail above, according to the developing device 1 of the present embodiment, the side seals 21 are provided in contact with both ends of the developing roller 12 in the axial direction. The side seal 21 is formed with a peak portion 21a, a valley portion 21b, and a wall portion 21e. Each peak portion 21 a spirally contacts the outer surface of the roller body portion 12 b of the developing roller 12. Further, the valley portion 21 b is deeper toward the center of the developing roller 12. The wall 21e contacts the end of the developing roller 12 in an arc shape.

  Therefore, the toner adhering to the surface of the developing roller 12 is prevented from leaking to the outside by the wall portion 21e and scraped off by the peak portion 21a. Further, the scraped toner is conveyed toward the center along the valley portion 21b. Therefore, with a simple configuration, it is possible to reliably prevent toner leakage from the vicinity of the axial end of the developing roller in the opening of the housing, and to bring the toner toward the central portion in the axial direction.

"Second form"
Next, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings. This embodiment is different from the first embodiment only in the shape of the side seal and its attachment portion, and common portions are denoted by common reference numerals and description thereof is omitted.

  In the developing device of this embodiment, a curved surface portion 17 as shown in FIG. 10 is used instead of the curved surface portion 16 (FIG. 2) of the housing 11 of the first embodiment. That is, the curved surface portion 17 is narrowed on the right side in the drawing to have a smaller diameter than the curved surface portion 16, and the left side in the drawing is a funnel-shaped portion 17 a that forms a conical surface coaxial with the curved surface portion 16. What is indicated by a broken line in the figure is the shape of the curved surface portion 16 in the first embodiment. The curved surface portion 17 does not come into contact with the surface of the developing roller 12 even at the most narrowed portion 17b.

  In this embodiment, a side seal 31 as shown in FIG. 11 is affixed to the funnel-shaped portion 17 a of the curved surface portion 17. In this side seal 31, the arrangement of the crests 31a is arranged at the same height as the crests 21a of the side seals 21 of the first embodiment. On the other hand, unlike the side seal 21, the valley portion 31 b is not a slope. All are the same depth. That is, the valley bottom surface 31f is parallel to the bottom surface 31c. When the side seal 31 is viewed from the right in the figure, the shape thereof is as shown in FIG. 5 as in the case of the side seal 21 of the first embodiment.

  In this embodiment, the side seal 31 is affixed to the funnel-shaped portion 17 a of the curved surface portion 17. Therefore, as it is, the side seal 31 is inclined as shown by a broken line in FIG. Therefore, the developing roller 12 is attached so that the side seal 31 in this state is crushed. That is, in the attached state, the side seal 31 is compressed between the developing roller 12 and the curved surface portion 17 in the thickness direction (left and right direction in FIG. 11). Thereby, as shown in FIG. 12, the crest 31 a and the wall 31 e of the side seal 31 come into contact with the surface of the developing roller 12. Further, the valley 31b with the developing roller 12 attached is inclined and arranged in the same manner as the valley 21b of the first embodiment.

  Also in this embodiment, since the side seal 31 is formed of a thermoplastic elastomer, it can be easily deformed in this way. In this way, the side seal 31 and the developing roller 12 are more strongly in contact with each other on the axial end portion side of the developing roller 12, so that toner leakage can be reliably prevented.

  Furthermore, as shown in FIG. 13, the side seal 21 of the first embodiment may be attached to the curved surface portion 17 of the present embodiment. Even in this case, it is possible to reliably prevent toner leakage. Further, in this case, the angle of the valley portion 21b becomes steep compared to the case of the first form or the case of using the side seal 31 in the second form, so that the scraper was scraped more reliably. The toner can be brought to the center.

  As described in detail above, the developing device of this embodiment also has a simple configuration and prevents toner leakage from the vicinity of the end portion in the axial direction of the developing roller in the housing opening, as in the first embodiment. This can surely prevent the toner and bring the toner toward the center in the axial direction.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, the shape of the housing other than the vicinity of the curved surface portions 16 and 17 at the end of the developing roller 12 is an example, and is not limited thereto. Moreover, although the material of the side seal is a thermoplastic elastomer, the material is not limited to this as long as sufficient elasticity and moldability are obtained. Also, the number of side seal crests and the inclination thereof can be changed.

It is a perspective view which shows the developing device of this form. It is a perspective view which shows the housing edge part of a state which removed the developing roller. It is sectional drawing of a developing device. It is a perspective view which shows the side seal of a 1st form. It is a top view which shows the side seal of a 1st form. It is sectional drawing which shows the developing device of a 1st form. It is sectional drawing which shows the developing apparatus of the other example of a 1st form. It is sectional drawing which shows the developing apparatus of the other example of a 1st form. It is sectional drawing which shows the developing apparatus of the other example of a 1st form. It is a perspective view which shows a part of housing of a 2nd form. It is a perspective view which shows the side seal of a 2nd form. It is sectional drawing which shows the developing device of a 2nd form. It is sectional drawing which shows the developing apparatus of the other example of a 2nd form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing device 11 Housing 12 Developing roller 12b Roller body part 16, 17 Curved surface part 21, 23, 24, 25, 31 Side seal 21a, 23a, 24a, 25a, 31a Mountain part 21b, 23b, 24b, 25b, 31b Valley part 21e wall

Claims (4)

A housing for storing the developer therein, and a developing roller that is rotatably supported by the housing and is partially exposed from the housing and develops a latent image on the image carrier at the exposed portion. In the developing device,
The housing is formed with a curved surface portion that faces the axial end portion of the cylindrical surface of the developing roller with a space therebetween,
The curved surface portion is attached with a flexible sealing material that partially contacts the cylindrical surface of the developing roller,
The sealing material includes
A wall that contacts the cylindrical surface of the developing roller in an arc shape;
A crest that is provided continuously from the wall on the axially central side of the developing roller with respect to the wall, and spirally contacts the cylindrical surface of the developing roller;
A valley portion that is disposed on the axially central side of the developing roller from the wall portion and at a position other than the peak portion and that does not contact the cylindrical surface of the developing roller is formed,
The direction of the spiral inclination of the peak portion is the direction that becomes the downstream side in the rotation direction of the developing roller as it approaches the axial center of the developing roller,
The developing device according to claim 1, wherein a surface of the valley facing the cylindrical surface of the developing roller is separated from the cylindrical surface of the developing roller as it approaches the center in the axial direction of the developing roller. The developing device according to claim 1,
The curved surface portion is a cylindrical surface coaxial with the cylindrical surface of the developing roller;
The developing device according to claim 1, wherein the thickness of the sealing material in the valley portion is reduced toward the axial center of the developing roller. The developing device according to claim 1,
The developing device, wherein the curved surface portion is a conical surface coaxial with a cylindrical surface of the developing roller. The developing device according to claim 3,
The developing device according to claim 1, wherein the sealing material is attached in a compressed state in a thickness direction between the housing and the developing roller.

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