JP3938114B2 - Development device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developing device provided in an image forming apparatus, and more particularly, to a configuration of a sealing unit that prevents leakage of toner at an opening portion where a developing roller of the developing device is disposed.
[0002]
[Prior art]
In an image forming apparatus configured as a facsimile machine, an electrophotographic copying machine, or a multi-function machine having a plurality of functions, an image forming means using an electrophotographic system is provided to transfer a toner image formed on a photosensitive member onto a sheet. The image is fixed on the recording paper. In the image forming apparatus, a charger, an exposure unit, a developing unit, a transfer unit, and a cleaning unit are arranged for the photosensitive member, and toner is supplied from a developing roller of the developing unit to the photosensitive drum to thereby generate a toner image. To form. In the developing device, the toner charged by the charging means from the toner hopper is attached to the developing roller, and then a blade member as a layer thickness regulating member made of a thin metal plate is pressed to form a thin layer. It is exposed at a position facing the body drum. The blade member is screwed to the upper part of the opening where the developing roller of the developing device frame is located, and the free end of the blade member is fixed with a predetermined pressing force using the spring property of the metal plate. It is comprised so that it may press. In addition, in the opening of the developing device provided with the developing roller, a seal member made of felt or sponge-like foam is provided on the photosensitive drum side in the surrounding portion, and both side portions of the blade and The toner is prevented from leaking from the vicinity of the end of the developing roller.
[0003]
[Problems to be solved by the invention]
Conventionally, since the blade member has the same width as that of the developing roller, the tip of the blade member (the corner portion bent in an L-shape) is provided with respect to the seal member provided at the opening of the frame of the developing device. Elastically contact and compress the seal member locally. However, since the sealing member is an elastic body, an elastic restoring force (repulsive force) against the compression action is applied, so that in addition to the elastic force of the blade member, a repulsive force from the sealing member is applied. Become. Therefore, the both end portions of the blade member strongly come into contact with both end portions of the developing roller, and there is a problem that the rotational load on the developing roller is increased due to the resistance.
[0004]
The present invention provides an apparatus in which toner leakage does not occur from the side portion of the blade member by defining the width of the blade member and providing a sealing material having elasticity at both end portions of the blade member. It is aimed.
[0005]
[Means for Solving the Problems]
In the present invention, the frame is formed with an opening that exposes the developing roller toward the photosensitive drum, and is held by a blade mounting portion provided at an upper portion of the opening and is bent into an L shape at the tip. A developing device in which a corner portion presses the developing roller to form a thin layer of toner carried on the developing roller, and the width of the blade member is smaller than the width of the developing roller. A first seal member that is formed in a substantially rectangular shape and has an inner surface that is in contact with both side portions of the blade member, covers a side edge portion of the opening, and contacts both side portions of the developing roller; and the seal member A lower film attached to the lower portion of the developing roller and sliding on the lower portion of the developing roller, and on both sides of the blade member, on the photosensitive drum side, on both sides of the first seal member A side film having elasticity provided corresponding thereto, a second seal member disposed on both sides of the blade member so as to be in contact with the end surface of the first seal member on the opposite side of the photosensitive drum, And a surface-side film that is disposed on the photosensitive drum side of the side film and is formed to have a width that covers the side film .
Accordingly, since the blade does not directly contact the first seal member disposed in the opening, the force with which the tip of the blade contacts the developing roller can be kept constant, and the load on the developing roller is prevented from increasing. In addition, the sealing performance can be exhibited well.
[0006]
And by providing so that the side surface of the 1st, 2nd sealing member may contact, the sealing effect by the said 2 sealing member can be maintained favorably.
[0007]
And since the side film provided on the surface side of the blade member has elasticity, it can be curved according to the curved shape of the blade member to cover the portion where the first and second seal members are in contact with each other. The toner can be prevented from leaking from the gap between the members.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the configuration of an image recording apparatus to which the apparatus of the present invention can be applied will be described with reference to FIG. The image recording apparatus 1 shown in FIG. 1 is configured as a small apparatus, and a paper feed tray 3 capable of storing paper of an arbitrary size is attached to a paper feed unit 2 provided at the lower part of the apparatus main body. Then, the paper is taken out one by one by the paper feed roller 4 and fed toward the paper transport path 5. In the paper transport path 5, transport roller devices 5a and 5b are arranged at a predetermined interval, and the paper transported in the paper transport path 5 is transferred from the photosensitive drum to the toner when passing through the recording unit 7. The image is transferred, fixed by the fixing device 8 to create a recording sheet, and discharged to a discharge tray 9 a by a discharge roller device 9. In addition to the paper feed system from the paper feed tray 3, a manual feed tray 6 that can be opened and closed is disposed on the side of the apparatus. When paper other than a standard size is used, the paper is fed from the manual feed tray 6 to the paper. So that the paper can be fed toward the paper transport path 5 by the paper feed roller 6a.
[0009]
In the image recording apparatus 1, the recording unit 7 includes a photosensitive unit 10 provided with a photosensitive drum 12 and a developing unit 20 for supplying toner to the photosensitive drum 12. The two units 10 and 20 are combined and mounted on the recording unit 7 of the apparatus main body as shown in FIGS. In the photosensitive unit 10, a charging member 15 and a memory removing member 14 are arranged with respect to the photosensitive drum 12 supported on the unit frame 11 via the shaft 13. Further, a writing means 16 is disposed at a position corresponding to the upper portion of the photosensitive drum 12, and a transfer member 17 is disposed at the lower portion. The photosensitive drum 12 rotated in the clockwise direction in FIG. On the downstream side, the developing roller 25 of the developing unit 20 is located.
[0010]
In the photoconductor unit 10, a predetermined voltage is applied to the photoconductor drum by a charging roller 15 as a charging unit, and image light is irradiated from a writing unit 16 constituted by an LED or the like to cause electrostatic latent images. Form an image. Then, toner is supplied from the developing roller 25 to the electrostatic latent image on the photosensitive drum 12 to form a toner image, and the sheet is conveyed between the transfer roller 17 and the photosensitive drum 12 and conveyed. On the other hand, a predetermined potential is applied to the transfer roller 17 to transfer the toner image onto a sheet. The sheet on which the toner image has been transferred is conveyed toward the fixing device 8, fixed, and discharged as a recording sheet. Further, after the toner image is transferred onto the sheet, the toner remaining on the photosensitive drum 12 after being transferred is disturbed by the brush of the memory removing member 14, and the adhesion is weakened and uniformly dispersed. After that, the toner is charged to a predetermined potential by the charging roller 15 and further mixed with the toner newly supplied from the developing roller and is reused.
[0011]
In order to supply the toner to the photosensitive drum 12, the developer unit 20 provided with a developing roller corresponding to the photosensitive drum is charged with the toner contained in the toner hopper 22 by the paddle 23. A mechanism is provided for feeding toward the supply roller 24 while stirring. Then, while rubbing the toner between the supply roller 24 and the developing roller 25, the toner is charged by applying a predetermined potential to adhere to the surface of the developing roller 25 and press the blade member 35. To form a thin layer. The toner carried on the developing roller 25 is supplied toward the electrostatic latent image on the photosensitive drum 12, but the toner remaining on the surface of the developing roller after that is newly supplied to the supply roller 24. The toner is mixed with the supplied toner, charged again, and supplied toward the development area.
[0012]
In order to position and hold the photosensitive drum 12 and the developing roller 25 at predetermined positions in combination with the photosensitive unit 10 and the developing unit 20, as shown in FIG. It is provided in a state of protruding from the frame 21. The connecting portion holder 27 is provided with a groove 28 into which the shaft 13 of the photosensitive drum 12 is inserted. By inserting the shaft of the photosensitive drum 12 into the groove 28, the unit 10 is connected to the developing unit 20. Thus, both units 10 and 20 can be accurately positioned with respect to the recording unit 7. Each of the two units 10 and 20 is supported by a recording unit (not shown) with respect to the recording unit of the apparatus main body, so that the photosensitive drum 12 and the developing roller 25 can be positioned relative to each other. It is also possible to use the connection part holder 27, and using the connection part holder 27 is not an essential requirement.
[0013]
In the developing unit 20 configured as described above, the opening 30 of the frame 21 that exposes the developing roller 25 toward the photosensitive drum 12 is provided above the opening 30 as shown in FIGS. A blade holding member 33 for holding the blade member 35 is provided on the blade mounting portion 31 provided in the portion. On the surface side (photosensitive drum 15 side) of the side frame member 21a of the frame around the opening 30, a substantially B-shaped seal member 32 is provided as a first seal member. As shown in FIG. 4, in the portion corresponding to the blade mounting portion 31, the seal member 32 is composed of a foam of open cells, and the bubbles are crushed by the compression action when fixing the blade member 35. This prevents toner through (toner leakage) from occurring.
[0014]
Further, since the seal member 32b provided below the blade attachment portion 31 so as not to contact the side portion on the back surface side of the blade is thermally compressed, even if the developing roller 25 is attached to the opening portion, a large compression is achieved. The action is not given, and the elasticity of the material itself can be exhibited, and the developing roller 25 is not strongly pressed locally. Since the thickness of the toner layer formed on the surface of the developing roller 25 is uniform at the position corresponding to the image area 25A, the toner transferred to the photosensitive drum 12 becomes a thin layer having a constant thickness. Therefore, a favorable recording image can be obtained without causing an inconvenience for the operation of transferring the toner from the developing roller 25 to the photosensitive drum 12 and the operation of transferring and fixing the toner image onto the paper. it can.
[0015]
The sealing member 32 is not compressed in advance, and the blade member 35 is fixed by the sealing member 32a corresponding to the blade mounting portion 31 even if the open-cell foam plate-like member is mounted as it is. The air bubbles are crushed by being pressed strongly to do so. Accordingly, in the portion where the bubbles of the seal member are crushed and compressed, there is no gap for the toner to leak, and at both ends of the opening of the seal member 32b that is not pressed, as will be described later, it cooperates with other seal means. Thus, the leakage of the toner can be prevented. Further, a lower film 40 is provided on the surface of the seal member where the seal member 32 contacts the developing roller, and the lower portion of the developing roller 25 slides smoothly on the lower film 40. Is done.
[0016]
The lower film 40 is made of a resin film having a smooth surface so as not to resist the rotation of the developing roller 25. For example, the lower film 40 is conventionally used as a paper guide unit in a paper conveyance path of an image forming apparatus. A PET (polyethylene terephthalate) film can be used. In addition, by providing the lower film 40 on the surface of the seal member 32, an effect based on the configuration that toner can be prevented from leaking through the seal member 32 can be achieved.
[0017]
In the blade holding member 33, as shown in FIG. 5, the mounting plate 34 provided to sandwich the upper part of the blade member 35 as the layer thickness regulating member is directed toward the blade mounting part 31 above the opening 30. It is attached in a pressed state and is arranged so as to hold the upper part of the blade member 35. Further, the mounting plate 34 is described as an example in which the holding member 38 is overlapped and then fixed with the fixing screw 33a. As shown in FIG. 7, the holding member 38 is arranged so that the upper bent portion 38 a covers the upper portion of the attachment portion of the blade member. Both sides of the blade member 35 are configured to be wider than the image area 25a of the photosensitive drum 25 but narrower than the length of the developing roller 25, and are substantially the same as the width of the blade member 35. The opening portion is provided so as to be in light contact with the inner surface of the seal member 32b. The blade member 35 is provided with a width with respect to the developing roller 25 so that a thin layer of toner can be satisfactorily formed in the range of the image region 25A. As shown in FIG. 5, the blade member 35 curved in a state where the lower end portion is pressed against the developing roller 25 is arranged along the surface of the side frame 21 a in the opening 30 of the unit frame (apparatus frame) 21. It is curved.
[0018]
As shown in FIGS. 6A to 6C, side films 36 and 36 are attached to the surface side (photosensitive unit side) of both side portions of the blade member 35, and the lower end portion of the blade member 35 is attached. Is curved according to the curved shape formed on the blade member 35 even when it is curved while being pressed against the developing roller 25. 6A shows the relationship between the blade member 35, the mounting plate 34, and the seal member 32, and FIG. 6B shows the relationship between the developing roller 25 and the blade member 35, respectively. ing. Moreover, although the whole structure of the braid | blade holding member 33 is demonstrated to the figure (c), the sealing member is abbreviate | omitted. In the example shown in FIG. 6 (a) and FIG. 6 (b), the side films 36, 36 provided on both sides of the blade member 35 are provided in correspondence with the portions on both sides of the seal member 32. It arrange | positions so that the top of the sealing member 32 may be covered.
[0019]
Similar to the seal member 32, a sheet-like seal member 37 made of a foam is provided on the back side of both side portions of the blade member 35 as a second seal member. The first seal member 32 provided at the opening 30 and the second seal member 37 provided at the back end of the blade 35 are positioned so that the end faces of the both are in contact with each other. It is provided so that the sealing action around can be maintained. The seal member 37 may be formed of a closed cell foam having a high density. A seal member 37a provided so as to be pressed against a portion to which the blade member 35 is attached by the holding member 38 is foamed with a low density. It is made of a material and can cope with the pressing action. Further, in the portion compressed by the mounting plate 34, the sealing action can be satisfactorily exhibited in a state where the sealing material 37a is compressed, and the uncompressed sealing material 37 below the elastic material is elastic against the sealing material 32. The elastic pressing action between the bodies is exerted on each other so that the sealing action can be performed.
[0020]
Further, as described above, the side films 36, 36 provided on the surface sides of the both side portions of the blade member 35 are provided so as to cover the side portions and the opening side portions of the blade 35, thereby allowing the opening to be opened. A gap is prevented from being generated on both sides of the part 30, and toner is prevented from leaking from the inside of the developing unit 20 through the opening 30 to the photosensitive drum side. That is, by arranging the first and second seal members, the toner leaks from the peripheral portion of the opening where gaps are likely to occur, such as the vicinity of the bearing of the developing roller and the portion where the two types of seal members are in contact. This prevents the toner from passing through the seal member (through) and leaking to the photosensitive drum side.
[0021]
As shown in FIG. 6C and FIG. 3, the surface side films 39, 39 arranged on both sides of the holding member 38 have a width so as to largely cover the surface side of the side film 36. The lower end portion thereof is extended to a position close to the developing roller 25. When the toner leaks from the upper side portion of the blade member 35, the leaked toner cloud or the like is applied to the writing member 16 such as an LED for writing image information on the photosensitive drum. The lower end portion of the film 39 is extended as close to the photosensitive drum as possible to effectively exert a shielding effect. Each of the film members 36 and 39 cooperates with the seal member 32 disposed around the opening to prevent the toner from leaking out from the periphery of the opening 30. Furthermore, as the film member, a thin resin film having an arbitrary elasticity can be used.For example, if a thin and transparent film such as a PET film is used and has a high strength, Durability can also be good.
[0022]
As shown in FIGS. 5 and 6, the mounting plate 34 disposed on the back side (blade mounting portion 31 side) of the blade member 35 may be formed of a relatively thick and rigid metal plate. Is possible. A compressed sealing material is provided on the back side of the blade member 35 and is positioned above the sealing member 37 so that a gap is not formed in the overlapping portion of the blade member 35 and the mounting plate 34. 37a is positioned. In addition, since the mounting plate 34 is made of a metal plate having a large rigidity and an arbitrary thickness, even if there is some unevenness on the surface of the blade mounting portion 31, a flat shape with respect to the blade member 35. A support part can be formed. As will be described later with reference to FIG. 7, the mounting plate 34 can be provided in a state where a plurality of plate members made of a thin and highly rigid metal plate are stacked.
[0023]
The holding member 38 positioned on the surface side of the blade member 35 is made of a relatively thick metal plate and can exhibit a large rigidity. As shown in FIG. 6C, a bent portion 38a is provided on the upper portion of the main body of the holding member 38 so as to protrude by a predetermined length, and the surface and the upper surface of the blade attachment portion 31 are provided. It is provided in a covering state. An electrode member 42 is provided on the side of the holding member 38 so as to protrude, and is in contact with a power supply terminal (not shown) provided on the apparatus main body on the side of the recording unit of the image recording apparatus. Thus, it is used to apply a predetermined voltage to the blade member 35. The holding member 38 is configured to be wider than the blade member 35 and the mounting plate 34, and the mounting plate 34 in contact with the blade mounting portion 31 and the blade member 35 stacked on the mounting plate 34, The blade mounting portions 31 at both ends are provided so as to cover more widely.
[0024]
Then, as described in FIGS. 6A to 6C, the seal member and the plate member are sequentially stacked, and then fixed by the fixing screw 33a. The fixing screw 33a penetrated together with the portion 31 is attached through screw holes 41... Provided in each plate member. For this purpose, each of the plate members 34, 35, 38 is positioned and provided so that the screw holes 41 overlap each other. In addition, among the plurality of screw holes arranged in the horizontal row, the screw hole provided at a predetermined position is formed as a long hole 41a so as to be consistent with the screw hole (not shown) of the blade mounting portion 31. It can be set well. In FIG. 6C, the electrode 42 provided on the side portion of the holding plate 38 is used to apply a voltage to the blade member 35, but the voltage application is not the gist of the present embodiment. Therefore, the explanation is omitted.
[0025]
In the mechanism that seals the opening 30 of the apparatus by the blade member 35, a seal member or the like as described below is arranged so that the toner accommodated in the developing device is placed on the photosensitive drum side. It is made not to leak out. In the embodiment of the blade fixing member, the mounting plate 34 and the holding plate 38 disposed so as to sandwich the blade member 35 can be arbitrarily set in thickness. In addition, the mounting plate 34 is not a single plate, but two or more plates are arranged in a stacked manner so that the holding action for the blade member can be more satisfactorily achieved, and the fixing portion of the blade member 35 by the screw 40 can be provided. Thus, it is possible to position and hold the blade member so as not to be uneven. For example, as shown in FIG. 7, additional plates 34 a and 34 b are arranged on the mounting plate 34 so that irregularities on the surface of the blade mounting portion 31 can be compensated by the stacked mounting plate. . A holding plate 38 that is pressed and held from the surface side of the blade 35 is inserted between the blade 35 and a metal plate having high rigidity similar to the mounting plate 34, and the pressing and holding action by the holding member 38. By using means such as providing a plurality of thin metal plates in a stacked manner, it is possible to achieve the same effect as the mounting plate.
[0026]
As shown in FIG. 6, for the plate member used as an auxiliary when mounting the blade, as shown in FIG. By using the means, it is possible to easily perform the operation of aligning the respective mounting members in a stacked manner. Therefore, as described above, when the upper portion of the blade member 35 is fixed and held with the screw 40, even if there are slight irregularities or manufacturing errors on the support surface of the plastic blade fixing member of the apparatus frame, The holding state can be set satisfactorily. Further, it is possible to satisfactorily exert the action of pressing the free side end portion of the blade member brought into contact with the developing roller, and the toner thin layer formed on the surface of the developing roller can be formed with a uniform thickness.
[0027]
As described above, in the embodiment of the blade fixing member, the mounting plate and the holding plate disposed so as to sandwich the blade member 35 can be arbitrarily set in thickness. Further, the mounting plate and the holding plate are arranged in a stack of two or more plates instead of one by one so that the holding action on the blade member can be exhibited better, and the blade member It is possible to position and hold the blade member so that no irregularities are formed on the blade member with the 35 screw fixing portions. Therefore, as described above, when the upper part of the blade member 35 is fixed and held with a screw, even if there is a slight manufacturing error on the support surface of the plastic blade fixing member, the holding state of the blade member is set well. Thus, it is possible to satisfactorily exert the action of pressing the free side end portion of the blade member to be brought into contact with the developing roller, and it is possible to form a thin toner layer formed on the surface of the developing roller with a uniform thickness.
[0028]
【The invention's effect】
The apparatus of the present invention is configured as described above, and since the blade does not directly contact the seal member disposed in the opening, the force with which the tip of the blade contacts the developing roller can be maintained constant. The load applied to the developing roller can be prevented from increasing and the sealing performance can be exhibited well. In addition, since the first and second sealing members are arranged so as to contact each other at the opening side of the frame, the sealing action by the two sealing members can be favorably maintained. Furthermore, since the film member provided on the surface side of the blade member has elasticity, the film member can be curved according to the curved shape of the blade member to cover the portion where the first and second seal members are in contact with each other. The toner can be prevented from leaking from the gap.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a configuration of an image recording apparatus.
FIG. 2 is an explanatory diagram illustrating a configuration of a recording unit.
FIG. 3 is an explanatory diagram of a state in which two units are combined.
FIG. 4 is an explanatory diagram showing a relationship of a seal of a developing device.
FIG. 5 is an explanatory diagram of a support structure for a blade member disposed in an opening of the developing device.
6A to 6C are explanatory views showing the relationship between the blade and the seal member, respectively.
FIG. 7 is an explanatory diagram of a blade mounting structure.
[Explanation of symbols]
1 image recording device, 2 paper feed unit, 3 paper feed tray,
4 paper feed roller, 5 paper transport path, 5a / 5b transport roller device,
6 Bypass tray, 7 Recording unit, 8 Fixing device,
9 discharge roller device, 10 photoconductor unit,
11 unit frame, 12 photosensitive drum, 13 drum shaft,
14 memory removal member, 15 charging member, 16 writing member,
17 transfer roller, 20 developer unit,
21 unit frame, 22 toner hopper, 23 paddle,
24 supply roller, 25 developing roller, 26 blade mounting portion,
27 connection part holder, 28 groove, 30 opening,
31 Blade mounting part, 32 Seal member,
33 blade holding member, 33a fixing screw, 34 mounting plate,
35 blade member, 36 side film, 37 seal member,
38 holding member, 39 surface side film,
41 screw holes, 42 electrodes.

Claims (1)

A frame formed with an opening that exposes the developing roller toward the photosensitive drum, and a corner portion that is held by a blade mounting portion provided at an upper portion of the opening and bent into an L shape at the tip is developed. A blade member that forms a thin layer of toner carried on the developing roller by pressing the roller, wherein the width of the blade member is smaller than the width of the developing roller,
A first seal member formed in a substantially round shape and having an inner surface in contact with both side portions of the blade member, covering a side edge portion of the opening, and contacting both side portions of the developing roller;
A lower film that is attached to the lower part of the seal member and slides on the lower part of the developing roller;
An elastic side film provided on both sides of the blade member on the photosensitive drum side in correspondence with portions on both sides of the first seal member;
A second seal member disposed on both sides of the blade member so as to be in contact with the end surface of the first seal member on the opposite side of the photosensitive drum;
A surface-side film disposed on the photosensitive drum side of the side film and formed to have a width covering the side film;
Developing apparatus is characterized in that it comprises.

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