JP5594093B2 - Development device - Google Patents

Description

  The present invention relates to a developing device including a developing roller (developer carrying member) that carries toner (developer) and a layer thickness regulating blade that slidably contacts the developing roller and regulates the thickness of toner on the developing roller. .

  In general, as a developing device, a rubber pressing member is provided at the tip of a layer thickness regulating blade, and the pressing member regulates the layer thickness by slidingly contacting a developing roller. In such a developing device, the toner tends to stay at both ends in the axial direction of the developing roller in the developing device, so that the layer thickness of the developing roller regulated by the layer thickness regulating blade is thicker at both ends than in the axial center. As a result, there is a problem that toner leakage occurs when used for a long time.

  On the other hand, there is conventionally known a technique in which the toner layer at both ends of the developing roller is made thinner than the center by changing the shape of the tip of the pressing member (see Patent Document 1). Specifically, in this technique, the central portion of the tip portion of the pressing member is formed in a curved shape (arc shape in cross section), and the both end portions are formed in an angular shape by being cut out.

  Thus, in the state where the tip of the pressing member is pressed against the developing roller, the angular end portions of the pressing member are pressed more strongly than the rounded central portion against the developing roller. It is possible to make the layer thickness of the part thinner than the central part.

JP 2003-195628 A

  However, in the technique described above, the pressure applied from the pressing member to the developing roller differs between the central portion and both end portions, so that the toner charging characteristics differ in the axial direction of the developing roller, and the image formation is good. There was a risk of not being done. Further, since the pressure at both ends of the pressing member is high, there is a possibility that the square ends may be scraped and the layer thickness regulation by the both ends cannot be performed due to long-term use.

  Therefore, an object of the present invention is to make the layer thickness at both ends of the developing roller thinner than the central portion while making the distribution of the charge amount of the toner in the axial direction of the developing roller substantially uniform.

The present invention that solves the above-described problems includes a housing that accommodates a developer, a developer carrier that is rotatably supported by the housing, and that supports the developer, and is provided in the housing, and has a tip portion. A layer thickness regulating blade that is in sliding contact with the developer carrying body to regulate the thickness of the developer on the developer carrying body, and both end portions of the tip of the layer thickness regulating blade in the axial direction of the developer carrying body And a seal member that is provided in the housing adjacent to and is in sliding contact with both end portions of the developer carrier, and is on the developer carrier by slidingly contacting the developer carrier. A scraping member that makes the developer layer thickness thinner than the layer thickness regulated by the layer thickness regulating blade is positioned upstream of the tip of the layer thickness regulating blade in the rotation direction of the developer carrier. And the inner side of the seal member in the axial direction of the developer carrier. The scraping member is provided on a surface opposite to the developer carrier of the casing or the layer thickness regulating blade so as to be adjacent to the casing, and the upstream end of the rotation direction of the scraping member is the developer carrier It is arrange | positioned so that it may slidably contact, and it is clamped between the said sealing member and the said housing | casing .

  According to the present invention, the scraping member is provided on the surface of the casing or the layer thickness regulating blade opposite to the developer carrier (that is, not provided between the layer thickness regulating blade and the developer carrier). The pressure applied to the developer carrier from the tip of the layer thickness regulating blade can be made substantially uniform in the axial direction, and the scraping member can be applied with a pressure smaller than the pressure applied to the developer carrier from the layer thickness regulating blade. It can be applied to the developer carrying member. Therefore, it is possible to suppress an increase in the charge amount of the developer at both ends due to friction between the scraping member and the developer carrier, and to make the distribution of the charge amount of the developer in the axial direction substantially uniform, Image defects can be suppressed. Furthermore, since the scraping member can be weakly applied to the developer carrying member, wear of the scraping member can be suppressed, and the effect of regulating the layer thickness by the scraping member can be maintained for a long period of time. it can.

  In addition, the upstream end of the scraping member in the rotation direction is brought into sliding contact with the developer carrying member, so that the surface of the scraping member is slidably brought into contact with the developer carrying member. Therefore, the layer thickness at both ends of the developer carrying member can be made thinner than that at the central portion without the scraping member being strongly applied to the developer carrying member. Therefore, charging of the developer and abrasion of the scraping member can be further suppressed.

  According to the present invention, it is possible to make the layer thickness at both ends of the developer carrying member thinner than the central portion while making the distribution of the developer charge amount in the axial direction of the developer carrying member substantially uniform.

1 is a side sectional view showing a laser printer provided with a developing cartridge according to an embodiment of the present invention. FIG. 6 is a side sectional view showing a developing cartridge. It is an expansion perspective view which shows the structure around a supply port. It is a front view which shows simply the structure around a supply port. It is the perspective view (a) which shows a scraping film, and sectional drawing (b). It is sectional drawing which shows the state which the scraping film is in sliding contact with the developing roller. It is a front view which shows simply the form which formed the front-end | tip part of the scraping film diagonally with respect to the rotation direction.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, the overall configuration of the laser printer will be briefly described, and then the features of the present invention will be described in detail.

  Further, in the following description, the description will be made in the direction based on the user when the laser printer 1 is used. That is, in FIG. 1, the right side toward the paper surface is “front side”, the left side is “rear side”, the back side in the vertical direction of the paper surface is “right side”, and the front side is “left side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

<Overall configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes a feeder unit 4 for feeding a sheet 3 into a main body casing 2 and an image forming unit 5 for forming an image on the sheet 3.

  The feeder unit 4 includes a paper feed tray 6 that is detachably attached to the bottom of the main casing 2 and a paper pressing plate 7 provided in the paper feed tray 6. The feeder unit 4 includes various rollers 11 that carry the paper 3 and remove paper dust. In the feeder unit 4, the sheet 3 in the sheet feeding tray 6 is moved upward by the sheet pressing plate 7 and conveyed to the image forming unit 5 by various rollers 11.

  The image forming unit 5 includes a scanner unit 16, a process cartridge 17, and a fixing unit 18.

  The scanner unit 16 is provided in the upper part of the main casing 2 and includes a laser light emitting unit (not shown), a polygon mirror 19 that is rotationally driven, lenses 20 and 21, and reflecting mirrors 22, 23, and 24. I have. In the scanner unit 16, the laser beam is irradiated on the surface of the photosensitive drum 27 by high-speed scanning through a path indicated by a two-dot chain line in the drawing.

  The process cartridge 17 can be attached to and detached from the main casing 2 by opening the front cover 2 </ b> A provided on the front side of the main casing 2. The process cartridge 17 is mainly composed of a developing cartridge 28 as an example of a developing device and a drum unit 39.

  The developing cartridge 28 is detachably attached to the main casing 2 while being attached to the drum unit 39. The developing cartridge 28 may be configured to be detachable from the drum unit 39 fixed to the main casing 2. As shown in FIG. 2, the developing cartridge 28 includes a developing roller 31 as an example of a developer carrier, a layer thickness regulating blade 32, a supply roller 33, and a toner storage chamber 34.

  In the developing cartridge 28, toner as an example of the developer in the toner storage chamber 34 is stirred by the agitator 34A and then supplied to the developing roller 31 by the supply roller 33. At this time, the supply roller 33 and the developing roller 31 are supplied. And positively triboelectrically charged. The toner supplied onto the developing roller 31 enters between the layer thickness regulating blade 32 and the developing roller 31 as the developing roller 31 rotates, and is further frictionally charged and the layer thickness is regulated to develop the developing roller. 31 is carried. Details of the developing cartridge 28 will be described later.

  The drum unit 39 includes a photosensitive drum 27, a scorotron charger 29, and a transfer roller 30. In the drum unit 39, the surface of the photosensitive drum 27 is uniformly positively charged by the scorotron charger 29 and then exposed by high-speed scanning of the laser beam from the scanner unit 16. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed.

  Next, by the rotation of the developing roller 31, the toner carried on the developing roller 31 is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 27, so that the toner image is formed on the surface of the photosensitive drum 27. It is formed. Thereafter, the sheet 3 is conveyed between the photosensitive drum 27 and the transfer roller 30, whereby the toner image carried on the surface of the photosensitive drum 27 is transferred onto the sheet 3.

  As shown in FIG. 1, the fixing unit 18 includes a heating roller 41 and a pressure roller 42 that is disposed to face the heating roller 41 and pressurizes the heating roller 41. In the fixing unit 18 configured as described above, the toner transferred onto the paper 3 is thermally fixed while the paper 3 passes between the heating roller 41 and the pressure roller 42. The sheet 3 thermally fixed by the fixing unit 18 is conveyed to a paper discharge roller 45 disposed on the downstream side of the fixing unit 18, and is discharged from the paper discharge roller 45 onto a paper discharge tray 46.

<Detailed structure of developing cartridge>
Next, the detailed structure of the developing cartridge 28 will be described. Since the developing cartridge 28 has a symmetrical structure, only one of the left and right parts is shown in FIG. 3 and the like, and the other part is omitted. In FIG. 3 and the like, the developing roller 31, the supply roller 33, and the like are appropriately removed as necessary.

  As shown in FIG. 3, the developing cartridge 28 is in sliding contact with a housing 50 that accommodates toner, a layer thickness regulating blade 32 and a blade seal member 62 that are in sliding contact with the upper side of the developing roller 31, and both ends of the developing roller 31. A side seal member 61 as an example of a seal member, a lower film 63 slidably in contact with the lower side of the developing roller 31, and a scraping film 80 as an example of a scraping member are provided.

  The housing 50 includes an outer wall 73 formed with a bearing 51 that rotatably supports the developing roller 31, a supply port 52 for supplying toner from the toner storage chamber 34 to the developing roller 31, and a side A side seal attaching surface 53 to which the seal member 61 is attached and a support portion 54 that supports the lower film 63 are formed. The supply port 52 is formed in a rectangular long hole shape along the axial direction of the developing roller 31, and the layer thickness regulating blade 32 is fixed to the upper portion so as to protrude downward.

The side seal attaching surfaces 53 are substantially arc-shaped surfaces when viewed from the side, and are formed on the left and right sides of the supply port 52.
The support portion 54 is formed below the supply port 52 so as to protrude toward the developing roller 31 side from the side seal attaching surface 53 and to extend along the axial direction of the developing roller 31.

  As shown in FIG. 2, the layer thickness regulating blade 32 is fixed to a metal plate 32A, reinforcing plates 32B and 32C that sandwich and reinforce the upper portion of the metal plate 32A, and a lower end portion (tip portion) of the metal plate 32A. And a pressing member 32D.

  As shown in FIG. 3, the pressing member 32 </ b> D is a rubber member having a smaller left-right width than the metal plate 32 </ b> A, and the outer corner (the corner that slides on the developing roller 31) at the lower end is all axial. It is formed to have a curved surface shape (arc shape in cross section) (see FIG. 2). Thereby, the pressure applied to the developing roller 31 from the tip end portion (pressing member 32D) of the layer thickness regulating blade 32 can be made substantially uniform in the axial direction.

  Further, a blade seal member 62 is adjoined on the metal plate 32A on the outer side in the left-right direction of the pressing member 32D. The configuration of the blade seal member 62 is the same as that of the side seal member 61 to be described later, so that the description thereof is omitted.

  As shown in FIG. 2, in the layer thickness regulating blade 32 configured as described above, the upper part of the metal plate 32A sandwiched between the reinforcing plates 32B and 32C is fixed to the housing 50, and the pressing member 32D at the lower end thereof. The blade seal member 62 (see FIG. 3) is in sliding contact with the developing roller 31 while receiving a biasing force from the metal plate 32A.

  A blade back seal 64 is disposed between the layer thickness regulating blade 32 and the housing 50. Specifically, the blade back seal 64 is formed in a U shape surrounding the upper portion of the supply port 52, and both end portions thereof are attached to the upper portion of the side seal attaching surface 53.

  As shown in FIG. 3, the side seal member 61 is provided between both end portions of the developing roller 31 and the side seal attaching surface 53. More specifically, the side seal member 61 is adjacent to the lower side of the lower end portions (the pressing member 32D and the blade seal member 62) of the layer thickness regulating blade 32 (the blade seal member 62) and the support portion 54 is disposed so as to be adjacent to the outside in the left-right direction.

  The side seal member 61 includes a base material 61A having elasticity and a surface member 61B laminated on the surface of the base material 61A on the developing roller 31 side. The base member 61A is formed of an elastic body such as an elastically deformable urethane sponge that is softer than the surface member 61B, and is attached on the side seal attaching surface 53 with a double-sided tape, an adhesive, or the like.

  The surface member 61B is made of a material such as felt thinner than the base material 61A, and is attached to the base material 61A with a double-sided tape or the like.

  The lower film 63 is a sheet-like member made of a resin such as polyethylene terephthalate, and extends along the axial direction of the developing roller 31. And this lower film 63 is formed in the left-right direction longer than the support part 54, and in the state affixed to the support part 54, the both ends protrude from the support part 54, and the side seal member 61 and They are arranged so as to overlap.

  A concave developer receiving portion 70 that opens only upward is formed on the rear side of the side seal member 61. Specifically, the developer receiving portion 70 includes a side seal attaching surface 53, a support portion 54, an outer wall portion 73 located on the outer side in the left-right direction of the side seal attaching surface 53, a side seal member 61, a housing. It is comprised by the flexible sheet | seat member 75 stuck along the rear-end part of the body 50. FIG. Thus, even when the toner on the blade seal member 62 is captured by the developing roller 31 and conveyed toward the side seal member 61, even if the toner is scraped and dropped at the edge of the side seal member 61. Since the toner can be received by the developer receiving portion 70, toner leakage from the developing cartridge 28 can be suppressed.

  The scraping film 80 is a sheet-like member made of a resin such as polyethylene terephthalate, and is disposed at a corner formed by the layer thickness regulating blade 32 and the side seal member 61 as shown in FIGS. ing. In other words, the scraping film 80 is adjacent to the lower side (the upstream side in the rotation direction of the developing roller 31) of the lower end portion (pressing member 32D) of the layer thickness regulating blade 32 and the inner side in the left-right direction (development) of the side seal member 61. The casing 50 is provided adjacent to the inner side of the roller 31 in the axial direction.

  Here, in this embodiment, the rotation direction of the developing roller 31 is a direction indicated by an arrow in FIGS. 3 and 4, and is a direction against the direction of the lower end portion of the layer thickness regulating blade 32. Specifically, the direction of movement of the surface of the developing roller 31 at the contact position between the developing roller 31 and the layer thickness regulating blade 32 is opposite (upward) with respect to the direction (downward) of the lower end portion of the layer thickness regulating blade 32. It has become.

  Specifically, as shown in FIGS. 5A and 5B, the scraping film 80 includes a sandwiching portion 81 sandwiched between the side seal member 61 and the housing 50, and an upward direction from the sandwiching portion 81. An extending portion 82 extending toward the developing portion 31 and a sliding contact portion 83 provided on the extending portion 82 and in sliding contact with the developing roller 31 are configured.

  The sandwiching portion 81 is a flat plate-like portion extending in the left-right direction, and a portion on the outer side in the left-right direction is sandwiched between the side seal member 61 and the side seal attachment surface 53. As a result, the sandwiching portion 81 is firmly held between the side seal member 61 and the side seal attaching surface 53 to which the developing roller 31 is pressed in a state where the developing roller 31 is assembled to the housing 50. It has become.

  The clamping portion 81 is formed with a length that protrudes inward in the left-right direction from the side seal member 61, and an extension portion 82 is formed on the side edge of the portion protruding inward in the left-right direction on the downstream side in the rotation direction. The seal member 61 is formed so as to extend toward the surface.

  The sliding contact portion 83 is formed so as to extend from the tip end of the extension portion 82 toward the upstream side in the rotation direction, and the tip end portion 83 </ b> A (end portion on the upstream side in the rotation direction) extends in the axial direction of the developing roller 31. It is formed so as to extend along (see FIG. 4), and is disposed so as to be in sliding contact with the developing roller 31, as shown in FIG. As a result, the toner on both ends of the developing roller 31 (specifically, the portion of the developing roller 31 adjacent to the inside in the left-right direction with respect to the portion in sliding contact with the side seal member 61) is scraped at the tip 83A of the sliding contact portion 83. Thus, it is possible to make the layer thickness at both end portions thinner than the layer thickness at the center portion (layer thickness regulated by the layer thickness regulating blade 32).

  In order to ensure that the tip 83A of the sliding contact portion 83 is in sliding contact with the developing roller 31, the tip 83A is attached to the developing roller 31 in a state before the developing roller 31 is attached to the housing 50. It is desirable to arrange it at a position on the outer side (developing roller 31 side) than the position (see FIG. 6). Accordingly, when the developing roller 31 is assembled, the sliding contact portion 83 is deformed until the tip end portion 83A is pushed inward by the developing roller 31 and positioned at the position in FIG. The tip 83A can be brought into sliding contact with the developing roller 31 with an appropriate pressure by the elastic force generated by the deformation of 83.

According to the above, the following effects can be obtained in the present embodiment.
Since the scraping film 80 is provided on the casing 50 (that is, not provided between the layer thickness regulating blade 32 and the developing roller 31), the pressure applied to the developing roller 31 from the tip of the layer thickness regulating blade 32 is substantially reduced in the axial direction. The scraping film 80 can be applied to the developing roller 31 with a pressure smaller than the pressure applied to the developing roller 31 from the layer thickness regulating blade 32. Therefore, it is possible to suppress an increase in the charge amount of the toner at both ends due to friction between the scraping film 80 and the developing roller 31, so that the distribution of the charge amount of the toner in the axial direction can be made substantially uniform, and the image Defects can be suppressed. Furthermore, since the scraping film 80 can be weakly applied to the developing roller 31, wear of the scraping film 80 can be suppressed, and the effect of layer thickness regulation by the scraping film 80 is maintained for a long period of time. be able to.

  Further, since the leading end 83A on the upstream side in the rotation direction of the scraping film 80 is brought into sliding contact with the developing roller 31, for example, the toner on the developing roller 31 is scraped compared to a structure in which the surface of the scraping film is in sliding contact with the developing roller. It becomes easy to take. For this reason, the layer thickness at both ends of the developing roller can be made thinner than the central portion even if the scraping film 80 is not strongly applied to the developing roller 31, thereby further suppressing charging of the toner and wear of the scraping film 80. be able to.

  By disposing the scraping film 80 adjacent to the tip of the layer thickness regulating blade 32, it is difficult for toner to be supplied to the surface of the developing roller 31 after scraping with the scraping film 80 (the layer thickness is reduced by scraping). The thinned toner immediately goes out through the layer thickness regulating blade 32), so that the layer thickness at both ends of the developing roller 31 can be surely reduced.

  Since the scraping film 80 is sandwiched between the side seal member 61 and the housing 50, for example, the scraping film is compared with a structure in which the scraping film is attached to the inner surface of the housing 50 (the edge of the supply port 52). 80 can be firmly fixed to the housing 50.

  Further, since the scraping film 80 is fixed to the housing 50, for example, the developing roller is in sliding contact with the developing roller 31 as compared with a structure in which the scraping film 80 is sandwiched between the base member 61A and the surface member 61B. Even when a radial force is applied from 31, vibration of the scraping film 80 can be suppressed, and the toner can be reliably scraped off.

  By forming the sliding contact portion 83 so as to extend from the distal end of the extending portion 82 toward the upstream side in the rotation direction, the upstream distal end portion 83A can be swung around the distal end of the extending portion 82. Therefore, the entire tip 83A can be brought into pressure contact with the developing roller 31, and the thickness of the defined width can be surely reduced.

  In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below. In the following description, the same reference numerals are given to members having substantially the same structure as in the above embodiment, and the description thereof is omitted.

  In the embodiment, the tip 83A of the sliding contact portion 83 is formed so as to extend along the axial direction of the developing roller 31, but the present invention is not limited to this. For example, as shown in FIG. 7, the tip end portion 83B (upstream end portion) of the sliding contact portion 83 is formed so as to incline toward the downstream side toward the inner side in the left-right direction (the inner side in the axial direction of the developing roller 31). May be.

  According to this, the toner scraped off at the front end portion 83B of the sliding contact portion 83 is moved inward in the left-right direction by the front end portion 83B inclined with respect to the rotation direction and the rotation of the developing roller 31, so that the inside of the housing 50 Therefore, the toner can be prevented from accumulating at the tip portion 83B, and the scraping effect at the tip portion 83B can be reliably exhibited.

  In the above-described embodiment, the scraping film 80 is provided on the casing 50. However, the present invention is not limited to this, and the space between the layer thickness regulating blade 32 and the developing roller 31 (from the layer thickness regulating blade 32 to the developing roller 31). Any place may be provided as long as the place is not affected by the applied pressure. For example, the scraping film may be fixed to the surface opposite to the developing roller 31 of the layer thickness regulating blade 32 in the embodiment (for example, the surface on the reinforcing plate 32B side of the metal plate 32A shown in FIG. 2). .

  In the above embodiment, the tip of the layer thickness regulating blade 32 is directed in the direction opposite to the rotation direction of the developing roller 31, but the present invention is not limited to this, and the tip of the layer thickness regulating blade is rotated by the developing roller. It may be directed in the direction following the direction (the same direction as the moving direction of the surface in sliding contact with the layer thickness regulating blade of the developing roller).

In the above-described embodiment, the developing cartridge 28 integrally including the toner storage chamber 34 is exemplified as the developing device. However, the present invention is not limited to this, and for example, a cartridge in which the toner cartridge having the toner storage chamber is attached and detached is used as the developing device. Also good.
In the above embodiment, the side seal member and the blade seal member are illustrated as having a two-layer structure. However, the present invention is not limited to this, and the seal member may have, for example, a one-layer structure or a three-layer structure or more.

  In the above-described embodiment, the layer thickness regulating blade 32 having the rubber pressing member 32D at the tip is employed. However, the present invention is not limited to this, and the rubber roller directly does not have a rubber pressing member. A stainless steel layer thickness regulating blade may be employed.

  In the said embodiment, although the sheet-like scraping film 80 was illustrated as a scraping member, this invention is not limited to this, For example, rod-shaped members, such as a square pole, etc. may be sufficient.

  In the above-described embodiment, the scraping film 80 is adjacent to the tip portion of the layer thickness regulating blade 32. However, the present invention is not limited to this, and the layer is located at a position upstream of the tip portion of the layer thickness regulating blade. You may arrange | position a little away from the front-end | tip part of a thickness control blade.

28 Developing Cartridge 31 Developing Roller 32 Layer Thickness Restricting Blade 32D Pressing Member 50 Housing 52 Supply Port 53 Side Seal Adhering Surface 61 Side Seal Member 80 Scraping Film 81 Nipping Portion 82 Extending Portion 83 Sliding Contact Portion 83A Tip

Claims (3)

A housing for containing the developer;
A developer carrier that is rotatably supported by the housing and carries the developer;
A layer thickness regulating blade that is provided in the housing and has a tip portion that is in sliding contact with the developer carrying member to regulate the thickness of the developer on the developer carrying member;
A developing device comprising: a seal member provided in the housing adjacent to both end portions in the axial direction of the developer carrying member at a tip portion of the layer thickness regulating blade, and being in sliding contact with both end portions of the developer carrying member. Because
A scraping member that makes the layer thickness of the developer on the developer carrying body thinner than the layer thickness regulated by the layer thickness regulating blade by slidingly contacting the developer carrying body, the tip of the layer thickness regulating blade The development of the casing or the layer thickness regulating blade is positioned upstream in the rotation direction of the developer carrier relative to the portion and adjacent to the inside of the seal member in the axial direction of the developer carrier. Provided on the surface opposite to the agent carrier,
The scraping member is disposed such that an upstream end in the rotation direction is in sliding contact with the developer carrier, and is sandwiched between the seal member and the housing. apparatus.   The developing device according to claim 1, wherein the scraping member is disposed adjacent to a tip portion of the layer thickness regulating blade. End of the upstream side of said scraping member, according to claim 1 or claim 2, characterized in that it is formed to be inclined to the downstream side toward the axially inner side of said developer carrying member Development device.

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