JP2011191330A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent toner stored in a casing of a developing device from leaking outside the casing. <P>SOLUTION: The developing device includes: the developing unit casing 51; a developing roller 52; an elastic blade 58; and a sealing member 59. The elastic blade 58 has: a support plate 58a; and a strip-like elastic layer 58b disposed on the support plate 58a along an axis direction. The elastic layer 58b is brought into contact with the circumferential surface of the developing roller 52 to form a thin toner layer on the developing roller 52. The sealing member 59 is disposed in the developing unit casing 51 so as to come into contact with the axial end of the developing roller 52, and the member 59 comes into contact with the end of the elastic layer 58b. A labyrinth structure 70 is formed between the end of the elastic layer 58b and the sealing member 59. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device having a seal member for preventing toner leakage from the developing device and an image forming apparatus including the developing device.

  An electrophotographic image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine includes a charger, an exposure device, a developing device, and a transfer device around a photosensitive drum. In such an image forming apparatus, the photosensitive drum is charged and further exposed to form an electrostatic latent image on the surface of the photosensitive drum. Thereafter, the electrostatic latent image is developed to form a toner image, and the toner image is further transferred onto a predetermined sheet.

  The developing device has a developing device casing, a developing roller, and a blade. The developing roller supplies the toner contained in the developing device casing to the photosensitive drum. The blade regulates the amount of toner on the developing roller by contacting the peripheral surface of the developing roller. In such a developing device, the developing roller is attached to the developing device casing in a state where a part of the developing roller is exposed from the opening of the developing device casing in order to contact the photosensitive drum. Therefore, there is a problem that toner leaks from the developer casing.

  In order to prevent toner leakage, a developing device is provided in which a plurality of seal members are provided near the opening of the developing device casing. Between a plurality of seal members, for example, another seal member having a convex shape, a concave shape, or a non-parallel shape is pressed against the surface of a certain seal member, and the shape such as the convex shape is compressed by pressing. (See, for example, Patent Document 1).

  On the other hand, a developing device that provides a toner layer regulating portion made of an elastic material on a blade and regulates the amount of toner on the developing roller by bringing the toner layer regulating portion into contact with the peripheral surface of the developing roller is provided (for example, Patent Document 2). Such a developing device has a seal member as shown in FIG. FIG. 5 is a diagram showing a positional relationship between a toner layer regulating portion and a seal member in a conventional developing device. In the developing device 10P, the seal member 21 is disposed so as to come into contact with the end portion 13a portion of the developing roller 13 and to be in close contact with the end surface 16a in the width direction of the toner layer regulating portion 16 of the elastic blade 15.

Japanese Patent Laid-Open No. 11-272071 Japanese Patent Application Laid-Open No. 07-301991

  In the developing device described in Patent Document 2, the width direction end portion 16a of the toner layer regulating portion 16 and the seal member 21 are in contact with each other at the end surfaces extending linearly. However, in such one-plane contact, the toner moving in the direction of the arrow as the developing roller rotates passes between the width direction end portion 16a of the toner layer regulating portion 16 and the seal member 21, and the developing device. It is difficult to prevent leakage to the outside of 10P. Further, when the seal member 21 is disposed so as to be pressed against the width direction end portion 16a of the toner layer regulating portion 16 in order to prevent toner leakage, a repulsive force against the pressing action acts toward the developing roller side. Therefore, there is a problem that the developing roller is damaged because the pressing portion strongly hits the developing roller due to the repulsive force. In addition, the contact between the toner layer regulating portion 16 and the developing roller 13 becomes non-uniform due to the pressing action. Therefore, there is a problem that the thickness of the toner formed on the developing roller 13 is not uniform.

  An object of the present invention is to make it difficult for toner contained in a casing of a developing device to leak out of the casing.

  A developing device according to an aspect of the present invention includes a casing that accommodates toner, a developing roller, an elastic blade, and a seal member. The developing roller is provided near the opening of the casing so as to be rotatable with respect to the casing. The elastic blade has a plate-like member provided along the axial direction of the developing roller and a strip-like elastic layer provided on the plate-like member along the axial direction of the developing roller, and develops the elastic layer. A thin layer of toner is formed on the developing roller by making contact with the peripheral surface of the roller. The seal member is provided in the casing so as to be in contact with the axial end portion of the developing roller, and is in contact with the end portion of the elastic layer. A labyrinth structure is formed between the end of the elastic layer and the seal member.

  Here, the labyrinth structure formed between the end portion of the elastic layer and the seal member refers to a configuration in which the end portion of the elastic layer and the seal member are not linear in contact portions between the end surfaces. By forming such a labyrinth structure between the end portion of the elastic layer and the seal member, it is possible to restrict the movement of the toner as the developing roller rotates. Therefore, the toner is less likely to leak out of the developing device casing from between the elastic layer and the seal member.

  The labyrinth structure has a first step portion provided at the end of the elastic layer so as to protrude along the axial direction of the developing roller, and a surface of a seal member that contacts the end of the elastic layer in the axial direction of the developing roller. You may consist of a combination with the 2nd level | step-difference part provided so that it might be depressed along.

  The labyrinth structure includes a convex portion provided at the end of the elastic layer so as to protrude along the axial direction of the developing roller, and a surface of a seal member that contacts the end of the elastic layer along the axial direction of the developing roller. You may consist of a combination with the recessed part formed so that it might become depressed.

  An image forming apparatus according to another aspect of the present invention includes a carrier capable of carrying an electrostatic latent image on a surface thereof and the developing device described above.

  In the present invention, by forming a labyrinth structure between the elastic layer and the seal member, the toner stored in the casing of the developing device is less likely to leak from between the elastic layer and the seal member to the outside of the casing.

1 is a schematic diagram illustrating a configuration of a main body of an image forming apparatus. Sectional drawing of a developing device. FIG. 3 is an enlarged view of the vicinity of a developing roller and an elastic blade. The figure which shows the positional relationship of the elastic blade and seal member in 1st Example. The figure which shows the positional relationship of the elastic braid | blade and seal member in 2nd Example. FIG. 6 is a diagram illustrating a positional relationship between a toner layer regulating portion and a seal member in a conventional developing device.

(1) Overall Image Forming Apparatus The image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram of an entire image forming apparatus including an embodiment according to the present invention. Hereinafter, in order to clarify the directional relationship in the image forming apparatus 1, the directions for the worker standing on the front surface (front side in FIG. 1) of the image forming apparatus 1 are defined as the left-right direction and the front-rear direction.

The image forming apparatus 1 includes an image reading device 2 and an image forming device main body 3.
The image reading apparatus 2 includes an image reading unit 21 and a document cover 22. The image reading unit 21 is a device that reads image data of a document, and is a so-called flatbed scanner. The image reading unit 21 includes a light source 23, a plurality of reflecting mirrors 24, and a scanner unit 25. In the image reading unit 21, the light irradiated and reflected from the light source 23 onto the original on the platen glass 26 is guided to the scanner unit 25 while being reflected by the plurality of reflecting mirrors 24. The document cover 22 is rotatably disposed on the image reading unit 21.

  The image forming apparatus main body 3 includes a housing 31, and an image forming unit 32, a fixing unit 33, a paper transport unit 34, a paper feed cassette 35, a manual paper feed tray 36, and a discharge unit provided inside the housing 31. A paper portion 37 is provided.

  The image forming unit 32 forms an image on the paper P based on the image data of the original read by the image reading device 2 and the image data sent from the personal computer. The image forming unit 32 includes a photosensitive drum 40, a charger 41, an exposure head 42, a developing device 43, a transfer roller 44, and a cleaning roller 45.

  The photosensitive drum 40 is a device that forms an electrostatic latent image on the surface. The photosensitive drum 40 is a columnar member that is rotatably provided. The photosensitive drum 40 is rotated counterclockwise in FIG. 1 about a rotation axis perpendicular to the paper surface direction of FIG. 1 by a driving device (not shown). The charger 41, the exposure head 42, the developing device 43, the transfer roller 44, and the cleaning roller 45 are provided in this order in the rotation direction of the photosensitive drum 40.

The charger 41 uniformly charges the surface of the photosensitive drum 40. The charger 41 is, for example, a corona discharge type device.
The exposure head 42 draws an electrostatic latent image along the image data by irradiating the surface of the charged photosensitive drum 40 with light. The exposure head 42 includes, for example, an LED (Light Emitting Diode) as a light source.

The developing device 43 supplies toner to the electrostatic latent image on the photosensitive drum 40 and develops the electrostatic latent image. Details of the developing device 43 will be described later.
The transfer roller 44 is disposed to face the photosensitive drum 40 and transfers the toner image on the photosensitive drum 40 onto the paper P.
The cleaning roller 45 removes the toner remaining on the photosensitive drum 40 after the transfer.

  The fixing unit 33 includes a heating roller and a pressure roller. The fixing unit 33 fixes the toner image on the paper P by applying heat and pressure to the paper P after the transfer.

  The paper transport unit 34 includes a transport path and a plurality of rollers. The paper transport unit 34 transports the paper P along the transport path by rollers, so that a paper discharge unit passes through the image forming unit 32 and the fixing unit 33 from a paper feed cassette 35 or a manual paper feed tray 36 described later. Up to 37, the paper P is conveyed.

The paper feed cassette 35 accommodates a bundle of paper P before image formation. The paper feed cassette 35 is provided so as to be able to be taken in and out of the housing 31.
The manual paper feed tray 36 has a manual paper feed function for special paper such as backing paper.
The paper discharge unit 37 is a part for discharging the paper P on which an image is formed. The paper discharge unit 37 is on the upper surface of the housing 31.

(2) Developing Device Next, the developing device 43 will be described in detail with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional view of the developing device. FIG. 3 is an enlarged view of the vicinity of the developing roller and the elastic blade.

  The developing device 43 is a device that develops an electrostatic latent image using toner. The developing device 43 includes a developing device casing 51, a developing roller 52 disposed in the developing device casing 51, a supply roller 53, a first toner chamber 54, a second toner chamber 55, a first stirring member 56, and a second stirring member. 57, an elastic blade 58, and a seal member 59.

  The developing roller 52 supplies the toner received from the supply roller 53 to the photosensitive drum 40, and develops the electrostatic latent image on the photosensitive drum 40 using the toner. The developing roller 52 is disposed along the inner wall 51 a of the developing device casing 51 at a position near the opening 62 of the developing device casing 51 and in contact with the photosensitive drum 40. The developing roller 52 has a roller shaft 52a and a roller body 52b made of a sponge material disposed around the roller shaft 52a, and rotates clockwise with respect to the developing device casing 51 in FIGS. Arranged as possible. Note that both end portions of the developing roller 52 in the axial direction are non-image forming regions R2 where image formation is not performed, and a seal member 59 described later is in contact with these portions. An area between the non-image forming areas R2 at both ends is an image forming area R1, and an elastic layer 58b of an elastic blade 58, which will be described later, is in contact with this area.

The supply roller 53 is disposed so as to be rotatable with respect to the developing device casing 51 at a position in contact with the developing roller 52. The supply roller 53 supplies the toner stored in the second toner chamber 55 to the developing roller 52.
The first toner chamber 54 and the second toner chamber 55 contain toner replenished from a toner cartridge (not shown). The first stirring member 56 and the second stirring member 57 are provided in each of the first toner chamber 54 and the second toner chamber 55, and send the toner toward the supply roller 53 while stirring the toner.

The elastic blade 58 makes the toner adhering to the developing roller 52 uniform and forms a thin toner layer on the developing roller 52. Specifically, the elastic blade 58 charges the toner on the developing roller 52 to regulate the thickness of the toner, and regulates the amount of toner held on the developing roller 52.
The elastic blade 58 will be further described with reference to FIG. 4A. FIG. 4A is a diagram illustrating a positional relationship between the elastic blade and the seal member in the first embodiment. FIG. 4A shows the positional relationship between the elastic blade 58 and the seal member 59 at the rear end portion of both end portions in the axial direction of the developing roller 52. On the other hand, the positional relationship between the elastic blade 58 and the seal member 59 at the front end portion of the developing roller 52 is symmetrical to the positional relationship shown in FIG. In FIG. 4A, in order to clearly show the positional relationship between the elastic blade 58 and the seal member 59, the developing roller 52 positioned on the near side in FIG. 4A is indicated by a dotted line. The direction of rotation of the developing roller 52 is indicated by an arrow.

  The elastic blade 58 has a support plate 58a and an elastic layer 58b. The support plate 58a is a belt-shaped metal plate-like member provided extending in the axial direction of the developing roller 52. The support plate 58 a is fixed to the developing device casing 51 at a first end portion in a direction intersecting with the axial direction of the developing roller 52. An elastic layer 58b is linearly attached to the second end of the support plate 58a.

  The elastic layer 58b is a thin band layer formed of a rubber material such as urethane or silicon. The back surface of the elastic layer 58b is attached to the support plate 58a, and the surface of the elastic layer 58b is in contact with the image forming region R1 on the peripheral surface of the developing roller 52. In the present embodiment, as shown in FIG. 3, the thickness of the elastic layer 58b is substantially the same as the thickness of the second seal member 61 of the seal member 59 described later. The end portion of the elastic layer 58b is in contact with the seal member 59, and a labyrinth structure 70 is formed between the elastic layer 58b and the seal member 59, which will be described in detail later.

The seal member 59 is provided in the developing device casing 51 so as to be in contact with both end portions in the axial direction of the developing roller 52, that is, the non-image forming region R2, and the toner leaks from the both end portions to the outside of the developing device casing 51. prevent. Further, a labyrinth structure 70 described later is formed on the seal member 59 on the contact surface with the elastic layer 58b.
The seal member 59 is composed of two layers of a first seal member 60 and a second seal member 61.

The first seal member 60 is a seal member made of sponge and is affixed on the inner wall 51 a of the developing device casing 51 so that a part thereof is along the outer periphery of the developing roller 52. The first seal member 60 is affixed on the inner wall 51a of the developing device casing 51 at a position where the side surface 60a contacts the rear end portion of the support plate 58a.
The second seal member 61 is a seal member made of Teflon (registered trademark) felt. The second seal member 61 is bonded onto the first seal member 60 so as to contact the peripheral surface of the non-image forming region R2 of the developing roller 52. Moreover, the 2nd level | step-difference part 611a or the recessed part 611b for forming the labyrinth structure 70 is formed in the side surface 61a side of the 2nd seal member 61 so that it may demonstrate below.

(3) Labyrinth Structure of Elastic Layer and Seal Member Next, the labyrinth structure 70 between the elastic layer 58b and the seal member 59 will be described.
The labyrinth structure 70 between the elastic layer 58b and the seal member 59 has a configuration in which the elastic layer 58b and the seal member 59 do not contact with each other in a linear plane, that is, even if there are two planes or one plane, for example, a curved line A structure that contacts in a non-linear plane such as a shape.
In the present embodiment, the labyrinth structure 70 is formed between the elastic layer 58 b and the second seal member 61 of the seal member 59. Hereinafter, the labyrinth structure 70 between the elastic layer 58b and the second seal member 61 will be described with reference to the first embodiment shown in FIG. 4A and the second embodiment shown in FIG. 4B.

(3-1) First Example As shown in FIG. 4A, a rear end portion of the elastic layer 58b protrudes rearward along the axial direction of the developing roller 52, that is, toward the non-image forming region R2. One step portion 581a is formed. More specifically, the first step portion 581a has a structure in which only one side in the left-right direction, here, the right side protrudes backward, and a step is formed between the protruding portion and the non-projecting portion. Further, on the side surface 61a of the second seal member 61 in contact with the first stepped portion 581a, the second stepped portion 611a recessed toward the rear side along the axial direction of the developing roller 52, that is, the inner side of the second seal member 61. Is formed. More specifically, in the second seal member 61, the side that is not in contact with the developing roller 52, that is, the right side portion in the left-right direction of the second seal member 61, is behind the portion that is in contact with the developing roller 52. It is a concave portion that is recessed. Therefore, in the 2nd seal member 61, the level | step difference is formed in the front-back direction between recessed parts and parts other than a recessed part. As shown in FIG. 4A, in the second stepped portion 611a of the second seal member 61, the first seal member 60 is exposed at a portion other than the first stepped portion 581a contacting.

In the first embodiment, the labyrinth structure 70 is formed by combining the first step portion 581a and the second step portion 611a. As a result, it is possible to prevent the toner from leaking from between the elastic layer 58 b and the second seal member 61 to the outside of the developing device casing 51.
That is, the toner that could not pass between the developing roller 52 and the elastic layer 58 b gradually moves toward both ends of the elastic layer 58 b and hits the side surface 61 a of the second seal member 61. Further, with the rotation direction of the developing roller 52, the toner moves toward the upstream side in the rotation direction of the developing roller 52, that is, the right direction shown in FIG. 4A.

  However, in this embodiment, the first stepped portion 581a of the elastic layer 58b and the second stepped portion 611a of the second seal member 61 are combined with each other so that the elastic layer 58b and the second seal member 61 come into contact with each other. Yes. That is, the elastic layer 58b and the second seal member 61 are in contact with each other on three surfaces. Furthermore, one of the three contact surfaces is a surface along the axial direction of the developing roller 52, in other words, a surface that intersects the moving direction of the toner accompanying the rotation direction of the developing roller 52. Accordingly, not only the contact area between the elastic layer 58b and the second seal member 61 is increased, but also the toner moving direction can be regulated. Accordingly, the toner is prevented from moving toward the upstream side in the rotation direction of the developing roller 52, and as a result, the toner is less likely to leak outside between the elastic layer 58b and the second seal member 61.

Further, the sticking of the seal member 59 to the inner wall 51a of the developing device casing 51 is performed manually by an operator. Accordingly, there is a variation in the pasting finish depending on the operator, and a gap may be generated between the elastic layer 58 b and the second seal member 61.
However, the elastic layer 58b and the second seal member 61 are in contact with each other as described above. Therefore, even if there is a gap in one of the three contact surfaces, for example, the movement of the toner can be regulated by the other contact surface. Further, due to the rotation by the developing roller 52, the second seal member 61 that contacts the developing roller 52 moves somewhat upstream. Therefore, even if a gap is generated on the contact surface that intersects the moving direction of the toner among the three contact surfaces, such a gap is filled by the above movement. As described above, by forming the labyrinth structure 70 between the elastic layer 58b and the second seal member 61, even if a gap is generated between the elastic layer 58b and the second seal member 61, the elastic layer The toner from between 58b and the second seal member 61 is difficult to leak.

(3-2) Second Example As shown in FIG. 4B, a convex portion 581b that protrudes toward the non-image forming region R2 along the axial direction of the developing roller 52 is formed at the rear end portion of the elastic layer 58b. Is done. More specifically, the convex portion 581b has a structure in which only a part of the central portion in the width direction of the rear end portion of the elastic layer 58b protrudes rearward. Further, on the side surface 61a side of the second seal member 61 that is in contact with the convex portion 581b, a concave portion 611b that is recessed inward along the axial direction of the developing roller 52 is formed. More specifically, the concave portion 611b has a structure in which only the portion of the second seal member 61 that is combined with the convex portion 581b is recessed backward.

  In the second embodiment, the labyrinth structure 70 is formed between the elastic layer 58b and the second seal member 61 by combining the convex portion 581b and the concave portion 611b. As a result, the toner is less likely to leak out of the developing device casing 51 from between the elastic layer 58 b and the second seal member 61.

That is, in the second embodiment, there are five contact surfaces between the elastic layer 58b and the second seal member 61, and two of the contact surfaces are surfaces along the axial direction of the developing roller 52, in other words, development. This is a surface that intersects the moving direction of the toner along with the rotation direction of the roller 52. Accordingly, it is possible to prevent the toner from moving toward the upstream side in the rotation direction of the developing roller 52 between the elastic layer 58 b and the second seal member 61.
Further, even if a gap is generated between the elastic layer 58b and the second seal member 61 due to the attachment by the operator, the gap between the elastic layer 58b and the second seal member 61 is the same as in the first embodiment. Toner is less likely to leak.

2. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

(1) In the above embodiment, the image forming apparatus having both the image reading apparatus 2 and the image forming unit 32 has been described. However, the present invention is not limited to this, and may be an image forming apparatus that does not have the image reading apparatus 2. Further, the image forming apparatus may be a multifunction machine having a facsimile function, a communication function, and the like.

(2) The labyrinth structure 70 is not limited to the above-described embodiment as long as the elastic layer 58b and the second seal member 61 are not in contact with each other on a linear plane. For example, a semicircular protruding portion that protrudes toward the non-image forming region R2 may be formed at the rear end portion of the elastic layer 58b. In addition, a semicircular groove that is recessed toward the inside may be formed on the side surface 61 a of the second seal member 61.

(3) In the above example, the second step member 611a or the recess 611b is formed in the second seal member 61. However, according to the thickness of the elastic layer 58b, not only the second seal member 61 but also the first seal member 60 may be formed with a second stepped portion or a recess similar to the second seal member 61. A labyrinth structure 70 may be formed between the elastic layer 58b and the second seal member 61 and the first seal member 60. However, in order to prevent toner leakage, it is preferable that the second step portion or the concave portion is not formed on the contact surface of the first seal member 60 with the inner wall 51a.

(4) In the above, the example in which the seal member 59 has the first seal member 60 and the second seal member 61 has been described. However, as long as the sealing member 59 has the same shape as the two sealing members 59, the sealing member 59 may be formed of one member or three or more members.

  The present invention can be applied to a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Image forming apparatus main body 31 Case 32 Image forming part 33 Fixing part 34 Paper conveyance part 35 Paper feed cassette 36 Manual paper feed tray 37 Paper discharge part 40 Photosensitive drum (carrier)
43 developing device 51 developing device casing 52 developing roller 53 supply roller 54 first toner chamber 55 second toner chamber 56 first stirring member 57 second stirring member 58 elastic blade 58a support plate (plate-shaped member)
58b Elastic layer 581a First step portion 581b Protrusion portion 59 Seal member 60 First seal member 60a Side surface 61 of the first seal member Second seal member 61a Side surface 611a of the second seal member Second step portion 611b Recess 62 Opening 70 Labyrinth structure R1 Image forming area R2 Non-image forming area

Claims (4)

A casing for containing toner;
A developing roller provided near the opening of the casing so as to be rotatable with respect to the casing;
A plate-like member provided along the axial direction of the developing roller; and a thin band-like elastic layer provided on the plate-like member along the axial direction of the developing roller; An elastic blade that forms a thin layer of toner on the developing roller by contacting the peripheral surface of the developing roller;
A seal member provided in the casing so as to contact an end portion in the axial direction of the developing roller, and contacting an end portion of the elastic layer;
With
A developing device in which a labyrinth structure is formed between an end of the elastic layer and the seal member.   The labyrinth structure has a first step portion provided at an end portion of the elastic layer so as to protrude along an axial direction of the developing roller, and a surface of the seal member that contacts the end portion of the elastic layer. The developing device according to claim 1, comprising a combination with a second step portion provided so as to be recessed along the axial direction of the developing roller.   The labyrinth structure includes a convex portion provided at an end portion of the elastic layer so as to protrude along an axial direction of the developing roller, and a surface of the seal member that contacts the end portion of the elastic layer. The developing device according to claim 1, comprising a combination with a recess formed so as to be recessed along the axial direction of the roller. A carrier capable of carrying an electrostatic latent image on its surface;
A developing device according to any one of claims 1 to 3,
An image forming apparatus.

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