JP4664052B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device that performs development by an electrophotographic developing method using a developer (hereinafter sometimes referred to as “toner”), and in particular, the layer thickness of a developer layer formed on a developing sleeve. The present invention relates to a developing device capable of achieving a more uniform layer thickness, and an image forming apparatus including the developing device.

  In general, in an image forming apparatus such as an electrophotographic developing printer, a facsimile, or a copying machine, a magnetic toner is used to form a toner image on the surface of a photosensitive member on which an electrostatic latent image based on image data of an original is formed. A developing device is provided for containing a one-component magnetic developer comprising:

  As a developing device for developing using this one-component magnetic developer, an electrostatic image on a latent image carrier is obtained by friction between magnetic toner particles and friction between a developing sleeve as a developer carrier and magnetic toner particles. For example, in the reversal development method, a charge having the same polarity is applied to the magnetic toner with respect to the charge and the development reference potential. The magnetic toner is applied very thinly on the developing sleeve, and the magnetic toner is conveyed to a developing area where the photosensitive member as the image bearing member and the developing sleeve are opposed to each other. In the development area, the magnetic toner flies and adheres to the electrostatic latent image on the surface of the photosensitive member due to the potential difference between the surface of the photosensitive member and the developing bias applied between the developing roller and the photosensitive member. Generally, an electrostatic latent image is visualized as a toner image.

In such a developing device, the layer thickness of the developer layer formed on the developing sleeve affects the image to be formed, and thus needs to be made more uniform. Therefore, conventionally, for example, a toner layer thickness regulating member that regulates the layer thickness of the toner layer formed on the developing sleeve is provided opposite to the developing sleeve containing the fixed magnet. The toner layer thickness regulating member includes a blade composed of a plate member made of a magnetic material, and a magnet attached to the upstream side of the developing sleeve in the rotating direction of the developing sleeve. The blade is a facing portion facing the developing sleeve. Is formed by thinly processing. (For example, refer to Patent Document 1).
Japanese Patent No. 2003-167426

  According to the configuration described in the above-mentioned patent document, the magnet is used, and the opposed portion of the blade facing the developing sleeve is formed thin, so that magnetic force concentration occurs on the facing portion of the blade, and the developing sleeve It is preferable because the toner layer can have a uniform thickness.

  However, it is necessary to process the opposing portion of the blade thinly, which requires time and effort for cutting. Further, the thinner the tip thickness, the more preferable the concentration of magnetic force increases, but the thinning is extremely difficult. In addition, variation occurs in the entire area of the member, and normally the limit is about 0.5 mm, and it is not possible to desire a concentration of magnetic force. Furthermore, in order to bring out the straightness of the facing portion that is the tip portion over the width direction that is the longitudinal direction of the developing sleeve of the blade, it is necessary to polish the tip portion, which increases the processing cost. There is.

  The present invention has been made to solve the above-described problems, and a developing device capable of making the layer thickness of the developer layer formed on the developing sleeve more uniform with a simple configuration, An object of the present invention is to provide an image forming apparatus including the developing device.

In order to achieve the above object, according to the first aspect of the present invention, the developer container containing the developer and a fixed magnet having a plurality of magnetic poles are included, and the developer is rotated to guide the developer onto the surface of the photoreceptor. In the developing device, comprising: a developing roller including a developing sleeve that is freely supported by a shaft; and a developer layer thickness regulating unit that regulates a layer thickness of the developer layer formed on the developing sleeve. thickness regulating means comprises a blade made of a thin plate of high permeability magnetic material, the early days including a blade auxiliary member made of a thick plate of ferromagnetic material, the tip of the blade faces the outer peripheral surface of the developing roller and that it, a gap is formed between an outer peripheral surface of the developing roller and the tip of the blade, said blade auxiliary member, et provided downstream in the rotation direction of the developing sleeve than the blade And that it, in that the blade support member in close contact with the downstream side in the rotational direction of the surface of the developing sleeve of Oite the blade is provided, between the outer peripheral surface of the developing roller and the blade support member A gap is formed, the distance between the blade auxiliary member and the developing roller increases toward the downstream side in the rotation direction of the developing sleeve, and the tip of the blade and the outer peripheral surface of the developing roller Is larger than the distance between the blade auxiliary member and the outer peripheral surface of the developing roller.

In the invention according to claim 2, the blade is arranged in the counter direction with respect to the rotation direction of the developing roller.
In the invention described in claim 3, the blade auxiliary member is made of ferritic stainless steel, martensitic stainless steel, silicon iron, or high nickel steel.
A fourth aspect of the present invention is an image forming apparatus including the developing device according to any one of the first to third aspects.

  According to the configuration of the first aspect of the present invention, the developer layer thickness regulating means includes a blade made of a thin magnetic material, a thick wall that is in close contact with the blade and provided downstream of the blade in the rotation direction of the developing sleeve. And a blade auxiliary member made of a magnetic material. Therefore, the structure is extremely simple, and the facing portion of the blade that faces the developing sleeve is formed thin as in the conventional case, so there is no need for cutting or polishing, and the number of processing steps can be reduced. , Processing costs can be reduced. In addition, by using a thinner blade, it is possible to easily improve the magnetic force concentration at the opposing portion of the blade.

Blade is so formed in a thin plate of high permeability magnetic material, it is possible to further improve the magnetic flux concentration of the facing portion of the blade, preferred.
The blade support member, a the side facing the developing roller, the side end surface of the photoreceptor side, so magnetic field lines are formed in a shape not concentrated, it is possible to further improve the magnetic flux concentration of the facing portion of the blade, preferable.

According to the configuration of the second aspect of the present invention, since the blade is arranged in the counter direction with respect to the rotation direction of the developing roller, the end surface of the opposed portion of the blade becomes extremely small, and the magnetic force concentration can be further improved. it can. Further, since the wedge shape is extremely small, the toner is not compressed, so that the flow of the toner in the portion is improved, the deterioration of the toner is prevented, and the toner layer thickness is thin and stable.

According to the configuration of the invention according to claim 4, since constituting an image forming apparatus including a developing device according to any one of claims 1 to 3, according to claims 1 to 3 above developed The same effect as the device can be obtained.

(First embodiment)
A specific first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic configuration diagram showing a schematic configuration when applied to a copying machine as an image forming apparatus using the developing device according to the first embodiment of the present invention.

  As shown in FIG. 1, a copying machine 1 serving as an image forming apparatus includes a sheet feeding unit 2 disposed at a lower portion of a copying machine main body 1a, and an image forming unit disposed above the sheet feeding unit 2. 3, a fixing unit 4 disposed on the discharge side of the image forming unit 3, and the image forming unit 3 and an image reading unit 5 disposed above the fixing unit 4. . Further, a paper transport unit 6 is formed from the recording paper P to the paper discharge unit 2 through the image forming unit 3 and the fixing unit 4.

  The paper feed unit 2 includes a plurality of paper feed cassettes 21 in which the recording paper P is accommodated, and a paper feed cassette 21 selected from the plurality of paper feed cassettes 21 by the rotation operation of the paper feed roller 22. The recording paper P is sent out to the paper transport unit 6 side. With this configuration, the recording paper P is reliably fed to the paper transport unit 6 one by one. These paper feed cassettes 21 are configured to be detachable from the copying machine 1.

  The recording paper P fed to the paper transport unit 6 is transported toward the image forming unit 3 via the paper supply path 61. The image forming means 3 forms a predetermined toner image on the recording paper P by an electrophotographic process, and is an image end holder that is rotatably supported in a predetermined direction (arrow direction in the figure). And a charging device 32, an exposure device 33, a developing device 34, a transfer device 35, a cleaning device 36, and a charge eliminating device 37 are provided around the photosensitive member 31 in the rotation direction.

  The charging device 32 includes a charging wire to which a high voltage is applied. By applying a predetermined potential to the surface of the photoreceptor 31 by corona discharge from the charging wire, the surface of the photoreceptor 31 is uniformly charged. It is done. Then, the exposure device 33 irradiates the photosensitive member 31 with light based on the image data of the original read by the image reading unit 5, whereby the surface potential of the photosensitive member 31 is selectively attenuated, and the photosensitive member 31 is exposed to light. An electrostatic latent image is formed on the surface of the body 31. Next, toner is attached to the electrostatic latent image by the developing device 34 to form a toner image on the surface of the photoconductor 31, and the toner image on the surface of the photoconductor 31 is transferred from the photoconductor 31 to the transfer device by the transfer device 35. 35 is transferred to the recording paper P supplied between the two.

  The recording paper P to which the toner image is transferred is conveyed from the image forming unit 3 toward the fixing unit 4. The fixing unit 4 is arranged on the downstream side of the image forming unit 3 in the sheet conveying direction. The recording sheet P onto which the toner image is transferred in the image forming unit 3 is a heating roller 41 provided in the fixing unit 4. The toner image is fixed on the recording paper P by being sandwiched and heated by the pressure roller 42 pressed against the heating roller 41. Next, the recording paper P on which the image is formed in the fixing unit 4 from the image forming unit 3 is discharged onto the discharge tray 25. On the other hand, after the transfer, the toner remaining on the surface of the photoconductor 31 is removed by the cleaning device 36, and the residual charge on the surface of the photoconductor 31 is removed by the static eliminator 37. The photosensitive member 31 is charged again by the charging device 32, and image formation is performed in the same manner.

  Next, the developing device will be described with reference to the drawings. FIG. 2 is a partial schematic cross-sectional view of the developing device in the copying machine according to the first embodiment of the present invention. As shown in FIG. 2, the developing device 34 according to this embodiment includes a developing container 7 that stores a magnetic one-component developer, and a pair of mixers 8 and 9 disposed in the developing container 7. Further, a fixed magnet 101 disposed on the opening side of the developing container 7 and having a plurality of magnetic poles, and containing the fixed magnet 101, and containing a magnetic developer (magnetic toner) on the surface of the photoreceptor 31. A developing roller 10 including a non-magnetic developing sleeve 102 rotatably supported for guiding is provided. Further, a developer layer thickness regulating means 11 is provided that hangs down from above the developing roller 10 toward the upper surface of the developing roller 10.

  As shown in FIG. 2, the magnetic pole of the fixed magnet 101 is an N-pole developing pole N1 near the developing position, and a portion located near the developing roller 10 of the developing container 7 on the downstream side of the developing sleeve 102 in the rotational direction of the developing pole N1. The shield pole S1 of the S pole at a position opposite to that, the pumping pole N2 positioned on the downstream side in the rotation direction of the developing sleeve 102 of the shield pole S1, and the developer layer thickness regulation on the upstream side in the rotation direction of the developing sleeve 102 of the development pole N1 S-pole blade poles S2 are arranged in the vicinity of the positions facing the means 11, respectively. The blade pole S2 is arranged slightly upstream in the rotation direction of the developing sleeve 102 of the developer layer thickness regulating means 11, and the lines of magnetic force emitted from the blade pole S2 face the developing sleeve 102 of the developer layer thickness regulating means 11. It is configured to concentrate on the opposite portion, that is, the tip portion 11a of the blade 111 described later.

  A toner replenishing hole 72 is opened on the upper surface of the developing container 7 above the mixer 8 so that the toner can be supplied by the toner cartridge 12. The introduced toner is sufficiently stirred by the pair of mixers 8 and 9 and guided to the developing sleeve 102. The magnetic toner guided to the developing sleeve 102 is carried on the developing sleeve 102 using the magnetic force of the fixed magnet 101, and the magnetic toner is disposed above the developing roller 10 and acts as a toner layer thickness regulating member. The developer layer thickness regulating means 11 controls the thickness. Thereafter, the magnetic toner carried on the developing sleeve 102 is guided from the developing position onto the surface of the photoreceptor 31 by the developing roller 10.

  The developing sleeve 102 is set to a predetermined peripheral speed, and the developing sleeve 102 is set to rotate in the same direction between the drum and the sleeve with respect to the rotation direction of the photosensitive member 31 (see FIG. 2). . The developing sleeve 102 is disposed at a predetermined distance from the photoconductor 31.

  Next, the configuration of the developer layer thickness regulating means 11 according to the characteristic part of the present invention will be described with reference to FIGS. FIG. 3 is an enlarged sectional view for explaining the developer layer thickness regulating means shown in FIG. 2, and FIG. 4 is an exploded perspective view for explaining the developer layer thickness regulating means shown in FIG.

  As shown in FIGS. 3 and 4, the developer layer thickness regulating means 11 is provided on the blade 111 made of a thin magnetic material, and is in close contact with the blade 111 and provided downstream of the blade 111 in the rotation direction of the developing sleeve 102. The blade auxiliary member 112 is formed of, for example, an angle formed of a thick magnetic material. More specifically, the blade 111 and the blade auxiliary member 112 insert the bolt 113 into the through holes 111 a and 112 a provided in the blade 111 and the blade auxiliary member 112, and the bolt 113 and the flange portion 71 of the developing container 7. The developer container 7 is attached by fastening means including a screw hole 7a and the like. At the time of this fastening, the blade 111 is positioned by, for example, inserting the half punch 112c formed in the blade auxiliary member 112 into the hole 111c provided in the blade 111 and the hole 7c provided in the flange portion 71. In this way, the positioning accuracy of the blade 111 can be improved very easily.

  The blade 111 made of a thin plate of this magnetic material is, for example, a ferritic stainless steel (for example, SUS430), martensitic stainless steel (for example, SUS403, SUS410), a permender, or the like, which is a magnetic material having a thickness t1 of 0.1 mm. Further, it is composed of permalloy or supermalloy such as high-permeability magnetic material such as high nickel steel. A preferable range of the thickness t1 of the blade 111 is 0.02 mm to 0.3 mm. Further, the protruding length L of the tip 11a of the blade 111 may be set as appropriate within a range of 0.1 mm to 1 mm.

  Since the blade 111 is formed of a thin plate, when the blade 111 is formed from a thin plate of raw material, it can be formed by, for example, a photoetching process. As described above, when the photoetching process is used, the straightness and flatness of the tip portion 11a, which is the facing portion facing the developing sleeve 102, can be made easier over the width direction of the developing sleeve 102 of the blade 111. Can get to. In addition, through-holes 111a used when the blade 111 is mounted on the developing container 7 can be simultaneously created by the photoetching process, so that the dimensional accuracy of the mounting position can be improved and the processing cost can be reduced.

  The blade auxiliary member 112 made of a thick magnetic material is, for example, a ferritic stainless steel (for example, SUS430) or a martensitic stainless steel (for example, SUS403, SUS410), which is a magnetic material having a thickness t2 of 1 mm. It is composed of silicon iron such as permender, and further permalloy and supermalloy such as high nickel steel which is a high permeability magnetic material. A preferable thickness t2 of the blade auxiliary member 112 is 1 mm or more, and it is sufficient that the blade 111 can be firmly supported without bending. Further, the thicker one receives more magnetic force from the developing roller 10, that is, the fixed magnet 101, as the developer layer thickness regulating means 11, and the magnetic force concentration at the tip 11 a of the blade 111 is further improved. Can do.

  The side end surface 112b of the blade auxiliary member 112 facing the developing roller 10 on the side of the photoreceptor 31 is formed in a shape in which corners are obtuse or curved, and magnetic lines of force are not concentrated on the side end surface 112b. . This configuration is preferable because the concentration of magnetic force at the tip of the developer layer thickness regulating means 11, that is, the tip 11a of the blade 111 can be further improved.

  According to the present embodiment having the above configuration, the developer layer thickness regulating means 11 is in close contact with the blade 111 made of a magnetic thin plate and the blade 111, and on the downstream side in the rotation direction of the developing sleeve 102 in the blade 111. The blade auxiliary member 112 made of a thick magnetic material is provided. Therefore, the configuration is extremely simple, and the tip portion 11a of the blade 111 facing the developing sleeve 102 is formed thin as in the prior art, so there is no need for cutting or polishing, and the number of processing steps is reduced. Reduction can be achieved and processing costs can be reduced. Further, by using a thinner blade 111, it is possible to easily concentrate the magnetic force at the tip 11a of the blade 111.

Further, since the blade 111 is formed of a thin plate of a high magnetic permeability magnetic body, the magnetic force concentration at the tip 11a of the blade 111 can be further improved, which is preferable.
Further, the side end surface 112b on the side of the photosensitive member 31 on the side facing the developing roller 10 of the blade auxiliary member 112 is formed in a shape that does not concentrate magnetic field lines. Can be further improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a partial schematic sectional view of the developing device in the copying machine according to the second embodiment of the present invention. FIG. 6 is an enlarged sectional view for explaining the developer layer thickness regulating means shown in FIG. 5 and FIG. 6, the portions denoted by the same reference numerals as those in FIGS. 1 to 4 described above are substantially the same, and thus detailed description thereof is omitted here. Hereinafter, the difference from the above-described embodiment will be mainly described.

  In this embodiment, as shown in FIGS. 5 and 6, the developer layer thickness regulating means 11 is in close contact with the blade 111 made of a magnetic thin plate and the blade 111, as in the above-described embodiment. 111, and a blade auxiliary member 112 made of a thick magnetic material provided on the downstream side of the developing sleeve 102 in the rotation direction. The blade 111 is arranged in the counter direction with respect to the rotation direction of the developing roller 10. More specifically, the flange portion 71 to which the developer layer thickness regulating means 11 of the developing container 7 is attached is formed in a shape that is inclined in the counter direction with respect to the rotation direction of the developing roller 10, and extends along the flange portion 71. In this way, the blade 111 and the blade auxiliary member 112 insert the bolt 113 into a through hole (not shown) provided in the blade 111 and the blade auxiliary member 112, and the bolt 113 and the flange portion 71 of the developing container 7. It is attached by fastening means consisting of a screw hole (not shown) provided in.

  With this configuration, the end surface of the tip portion 11a of the blade 111 has a very small wedge shape, and excess toner regulated by the portion smoothly flows back into the developing container 7 and is not compressed in the portion. .

  According to the present embodiment having the above-described configuration, the developer layer thickness regulating means 11 can be configured with an extremely simple configuration, as in the above-described embodiment, and the tip end portion 11a of the blade 111 facing the developing sleeve 102 is conventionally provided. In order to form a thin film like this, there is no need for cutting or polishing, the number of processing steps can be reduced, and the processing cost can be reduced. Further, by using a thinner blade 111, it is possible to easily concentrate the magnetic force at the tip 11a of the blade 111.

  Furthermore, since the blade 111 is disposed in the counter direction with respect to the rotation direction of the developing roller 10, the end surface of the tip end portion 11a of the blade 111 becomes extremely small, and the magnetic force concentration can be further improved. Further, since the wedge shape is extremely small, the toner is not compressed, so that the flow of the toner in the portion is improved, the deterioration of the toner is prevented, and the toner layer thickness is thin and stable.

  Each embodiment described above is a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

  For example, in each of the above-described embodiments, the copying machine has been described as an example. However, the present invention has, for example, a printer device, a facsimile device, and various functions such as a copy function, a printer function, a scanner function, and a facsimile function. The present invention can also be applied to multifunction devices.

  In this embodiment, the drum-shaped photoconductor 31 is used. However, the shape of the photoconductor 31 is not limited, and a known shape other than the above-described drum shape can be used. Examples of the shape include a sheet shape, a belt shape, and a web shape.

  In the embodiment described above, no magnet is provided on the developer layer thickness regulating means 11 side, but a magnet may be provided in order to further improve the magnetic force concentration of the tip 11a of the blade 111. Of course. In this case, when a magnet having the same magnetic force as before is used, the concentration of magnetic force can be further improved.

  Examples of utilization of the present invention include a developing device that performs development by an electrophotographic developing method using a developer, and an image forming apparatus including the developing device.

FIG. 2 is a schematic configuration diagram showing a schematic configuration when applied to a copying machine as an image forming apparatus using the developing device according to the first embodiment of the present invention. 1 is a partial schematic cross-sectional view of a developing device in a copying machine according to a first embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view for explaining the developer layer thickness regulating means shown in FIG. 2. FIG. 3 is an exploded perspective view for explaining developer layer thickness regulating means shown in FIG. 2. FIG. 6 is a partial schematic cross-sectional view of a developing device in a copying machine according to a second embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view for explaining the developer layer thickness regulating means shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 7 ... Developing container, 10 ... Developing roller, 11 ... Developer layer thickness regulating means, 31 ... Photoconductor, 34 ... Developing device, 101 ... Fixed magnet, 102 ... Developing sleeve, 111 ... Blade, 112 ... Blade auxiliary member, 112b ... Side end face

Claims (4)

A developing container containing a developer; a developing roller including a fixed magnet having a plurality of magnetic poles; and a developing sleeve rotatably supported to guide the developer onto the surface of the photoreceptor; and the developing A developer layer thickness regulating means for regulating the layer thickness of the developer layer formed on the sleeve;
The developer layer thickness regulating means comprises a blade made of a thin plate of high permeability magnetic material, the early days including a blade auxiliary member made of a thick plate of ferromagnetic material,
The tip of the blade faces the outer peripheral surface of the developing roller;
A gap is formed between the tip of the blade and the outer peripheral surface of the developing roller;
Said blade support member is provided on the downstream side in the rotating direction of the developing sleeve than the blade,
Said blade support member in close contact is provided with the downstream side in the rotating direction of the surface of the developing sleeve of Oite to the blade,
A gap is formed between the blade auxiliary member and the outer peripheral surface of the developing roller;
The distance between the blade auxiliary member and the developing roller increases toward the downstream side in the rotation direction of the developing sleeve;
The distance between the tip of the blade and the outer peripheral surface of the developing roller is larger than the distance between the blade auxiliary member and the outer peripheral surface of the developing roller.
A developing device. The developing device according to claim 1, wherein the blade is disposed in a counter direction with respect to a rotation direction of the developing roller. The developing device according to claim 1, wherein the blade auxiliary member is made of ferritic stainless steel, martensitic stainless steel, silicon iron, or high nickel steel. An image forming apparatus comprising the developing device according to claim 1 .

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