JP4247600B2 - Development device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to electrophotographic image formation such as a printer, a copying machine, and a facsimile apparatus that visualizes an electrostatic latent image formed on an image carrier such as a photosensitive drum or a photosensitive belt by attaching toner. The present invention relates to a developing device used in the apparatus.
[0002]
[Prior art]
In a developing device using a known non-magnetic one-component developer, a toner layer regulating blade is brought into contact with the developing roller to form a thin layer of toner on the developing roller, and the toner is triboelectrically charged. Is brought into contact with or close to the image carrier to visualize the electrostatic latent image formed on the image carrier.
[0003]
Conventionally, in an image forming apparatus equipped with such a developing device, a transfer material conveyance path or an intermediate transfer belt is disposed below an image forming unit including an image carrier, a charging device, an exposure device, a developing device, and the like. Generally, the problem is that the transfer device and transfer material are contaminated by the scattering of toner from the developing device, and the exposure unit is placed on the upper part of the device, so that it is easy to pick up the vibration of the device and make stable exposure difficult. Has the problem.
[0004]
In order to solve these problems, there is known an image forming apparatus in which a transfer material conveyance path or an intermediate transfer belt is arranged above an image forming unit (for example, Japanese Patent Laid-Open No. 7-44011). With this arrangement, the image carrier is rotated in the moving direction of the transfer material conveyance path or the intermediate transfer belt. Therefore, the rotation of the developing roller of the developing device is increased at the contact portion with the image carrier. The toner layer regulating blade is arranged downstream of the contact portion between the developing roller and the developer supply roller in the rotation direction.
[0005]
In the developing device disclosed in Japanese Patent Application Laid-Open No. 7-44011 configured as described above, the deteriorated toner that has passed between the developing roller and the supply roller and has been excluded by the regulating blade is returned to the toner storage unit and stored in the toner storage unit. The supply roller is rotated in the same direction at the contact portion with the developing roller. However, this method has a problem that the efficiency of collecting deteriorated toner in the toner storage unit is poor.
[0006]
Therefore, in Japanese Patent Laid-Open No. 2002-189345, the toner circulation region forming means (the distance between the supply roller and the bottom wall of the developing device) is configured to be the narrowest on the regulating blade side, and is generated at the contact portion or the contact portion. The deteriorated toner is efficiently flowed to the toner storage portion.
[0007]
[Patent Document 1]
JP 7-44011 A [Patent Document 2]
JP2002-189345
[0008]
[Problems to be solved by the invention]
However, in the conventional developing device, a relatively wide space is formed at the contact portion between the developing roller and the supply roller and the contact portion between the developing roller and the toner layer regulating blade, and the deteriorated toner is compressed into the dust. This causes a problem that the toner stays in a state and toner leaks from the sealing member on the back of the regulating blade. As a result, there is a problem that the recovery of the deteriorated toner to the toner storage portion does not proceed and an image defect caused by the deteriorated toner is caused.
[0009]
The present invention solves the above-described conventional problems, and prevents toner from being compressed near the regulating blade, prevents toner from leaking to the back of the regulating blade, and collects deteriorated toner in the toner reservoir. It is an object of the present invention to provide a developing device that can be efficiently performed.
[0010]
[Means for Solving the Problems]
Therefore, the developing device of the present invention includes a toner carrier that transports toner to a developing position, a toner supplier that supplies toner to the toner carrier, a toner reservoir that transports toner to the toner supplier, and the toner Toner layer regulating means for regulating the toner layer thickness of the carrier, and a toner return path formed between the peripheral wall of the developing housing facing the toner supply body and the surface of the toner supply body below the toner supply body And a sealant disposed between the toner layer regulating means and the developing housing on the side forming the toner return path, and the toner carrier and the toner supply body are both downward at the contact position. It is rotated in the direction of rotation downstream from the contact position of the toner layer regulating means and the toner carrying member and the toner supply body, and the toner carrying member at the upstream side of the developing position Is contact with counter direction, in the developing device having the toner passage towards the toner recirculation passage in said toner supplying member and said toner layer regulating means and said sealing material is formed, the surface of the toner supply member of the toner passage the width of the toner passage formed between the tip of the sealing material, the wider than the toner passage formed between the surface of the toner supply member and the leading end of the toner layer regulating means and the toner and It is characterized by being narrower than the width of the portion of the reflux path where the width is the smallest .
Further, the thickness of the tip of the toner layer regulating means is larger than the thickness of the tip of the sealing material, and the toner layer regulating means is conductive.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an image forming apparatus equipped with one embodiment of a developing device according to the present invention.
In this image forming apparatus, an image carrier 2 composed of a photosensitive drum is disposed in the apparatus main body 1, and is rotationally driven in a direction indicated by an arrow D1 by a driving unit (not shown). Around the image carrier 2, a charging device 3, an exposure device 4, a rotary developing device 5, a transfer unit 6 and a cleaning device for uniformly charging the image carrier 2 along the rotational direction D1. Each device 7 is arranged.
[0012]
In the rotary developing device 5, a yellow developing device 5Y, a magenta developing device 5M, a cyan developing device 5C, and a black developing device 5K are rotatably provided around a shaft 12 by a driving means (not shown). ing. These developing units 5Y, 5C, 5M, and 5K selectively rotate the developing roller 13 of one developing unit to a position close to or in contact with the image carrier 2 for each rotation of the image carrier 2. The electrostatic latent image on the image carrier 2 is visualized with a selected toner color.
[0013]
The transfer unit 6 is opposed to the drive roller 61 and the driven roller 62, an intermediate transfer belt 63 suspended from the drive roller 61, drive means (not shown) for driving the intermediate transfer belt 63 to rotate in the arrow direction D 2, and the drive roller 61. And a secondary transfer roller 64 for transferring a four-color full-color image formed on the intermediate transfer belt 63 onto the transfer material S.
[0014]
A paper feed cassette 8 is disposed at the bottom of the apparatus main body 1, and the transfer material S in the paper feed cassette 8 passes through the transfer material conveyance path 9 in the direction indicated by the arrow D <b> 3 through the secondary transfer roller 64 and the fixing device 10. It is configured to be conveyed to the paper discharge tray 11.
[0015]
The operation of the image forming apparatus having the above configuration will be described. When an image forming signal is input from a computer (not shown), the image carrier 2, the developing device 5 and the intermediate transfer belt 63 are rotationally driven. First, the outer peripheral surface of the image carrier 2 is uniformly charged by the charging device 3. Then, the exposure device 4 performs selective exposure L according to the image information of the first color (for example, yellow) on the outer peripheral surface of the uniformly charged image carrier 2 to form a yellow electrostatic latent image. Is done.
[0016]
At the latent image position formed on the image carrier 2, the yellow developing device 5 </ b> Y rotates and the developing roller 13 comes into contact therewith, whereby the yellow electrostatic latent image toner image is transferred to the image carrier 2. Next, the toner image formed on the image carrier 2 is transferred onto the intermediate transfer belt 63 in the primary transfer region T1. At this time, the secondary transfer roller 64 is separated from the intermediate transfer belt 63.
[0017]
In accordance with the second color, the third color, and the fourth color of the image formation signal, the above processing is repeated to form a latent image, develop, and transfer by one rotation of the image carrier 2 and the intermediate transfer belt 63, thereby forming an image. Four color toner images corresponding to the signal contents are superimposed and transferred on the intermediate transfer belt 63.
[0018]
Then, at the timing when the full-color image reaches the secondary transfer roller 64, the transfer material S is supplied from the transfer material conveyance path 9 to the secondary transfer region T2, and at this time, the secondary transfer roller 64 is pressed against the intermediate transfer belt 63. At the same time, a secondary transfer voltage is applied, and the full-color toner image on the intermediate transfer belt 63 is transferred onto the transfer material S. Then, the toner image transferred onto the transfer material S is heated and pressed by the fixing device 10 to be fixed, and is discharged to the paper discharge tray 11.
[0019]
2 and 3 show an embodiment of the developing device of the present invention, FIG. 2 is an enlarged cross-sectional view of the developing device of FIG. 1, and FIG. 3 is an enlarged view of a main part of FIG.
In FIG. 2, the developing devices 5Y, 5C, 5M, and 5K of the rotary developing device 5 are arranged so as to be divided into four equal parts in a circle of the cylindrical frame 14, and the frame 14 is centered on the shaft 12. A driving means (not shown) is provided so as to be rotatable in the direction indicated by the arrow. Hereinafter, the developing device 5Y will be described as a representative.
[0020]
Each of the developing devices 5Y, 5C, 5M, and 5K includes a developing housing 15. In the developing housing 15, a developing roller (toner carrying member) 13 that conveys toner to a developing position that faces the image carrier 2 is provided. A supply roller (toner supply body) 16 that supplies toner to the developing roller 13, a toner storage portion 17 that conveys toner to the supply roller 16, a toner layer regulation regulating means 19, and a development housing 15 that faces the supply roller 16 A toner reflux path 20 formed between the peripheral wall 15a and the peripheral wall 15a is provided.
[0021]
Incidentally, as shown in FIG. 1, in the image forming apparatus in which the transfer unit 6 is disposed above the image carrier 2, the rotational direction D1 of the image carrier 2 is set to the conveyance direction D2 of the intermediate transfer belt 63. Therefore, the rotation direction D4 of the developing roller 13 of the developing device 5 is upward at the contact portion (or contact portion) with the image carrier 2, and is shown in FIG. As described above, the toner layer regulating means 19 is disposed downstream of the contact portion between the developing roller 13 and the supply roller 16 in the rotation direction and upstream of the developing position.
[0022]
In this case, the deteriorated toner that passes between the developing roller 13 and the supply roller 16 and is excluded by the regulating blade 19 needs to be returned to the toner storage portion 17 via the toner return path 20, and therefore the rotation direction of the supply roller 16 is Similar to the developing roller 13, the contact portion between the two faces downward.
[0023]
As shown in FIG. 3, the toner layer regulating means 19 includes a plate spring 19a having one end supported by the developing housing 15 by a support portion 21, and a rubber regulating blade 19b fixed to the other end of the plate spring 19a. It has become. Between the leaf spring 19a and the bottom wall 15a at the position of the regulating blade 19b, a sealing material 22 having elasticity weaker than the elastic force of the leaf spring 19a is disposed. The tip of the regulating blade 19b is in contact with the developing roller 13 in the counter direction (on the upstream side in the rotation direction of the developing roller 13 relative to the support portion 21 of the leaf spring 19a). The toner layer regulating means 19 may be composed of only a leaf spring or a rubber blade. In this case, the regulating blade 19b is replaced with the toner layer regulating means 19 in the following description.
[0024]
The present invention is characterized in that the distance L1 between the center of the supply roller 16 and the tip of the regulating blade 19b is smaller than the minimum distance L2 between the center of the supply roller 16 and the peripheral wall 15a of the developing housing 15. In this way, the tip of the regulation blade 19b protrudes from the developing housing peripheral wall 15a facing the supply roller 16, and the space surrounded by the supply roller 16, the development roller 13 and the regulation blade 19b is configured to be narrowed. The toner regulated by the blade 19b can be efficiently flowed toward the toner return path 20 by the rotation of the supply roller 16, and toner compaction in the vicinity of the regulation blade 19b can be prevented, and toner leakage from the sealing material 22 can be prevented. Can be prevented.
[0025]
In addition, preferably, the tip position of the sealing material 22 is set to be between the distances L1 and L2. Thereby, the passage cross section is expanded in the order of the regulating blade 19b, the sealing material 22 , and the peripheral wall 15a, and the toner can be more rectified. More preferably, the thickness of the tip of the regulating blade 19b is larger than the thickness of the tip of the sealing material 22 . Thereby, it is possible to prevent the regulated toner from leaking from the sealing material 22.
Further, the regulation blade 19b may be conductive. Thereby, it is possible to prevent excessively charged toner from electrostatically adhering to the tip of the regulating blade 19b, and to improve the toner flow. Table 1 below shows the evaluation of toner leakage in the sealing material 22 with respect to the thicknesses of the insulating rubber and the conductive rubber. In the case of the conductive rubber, the rubber thickness is 1.5 mm to 2.0 mm. I found out that
[0027]
【The invention's effect】
As is apparent from the above description, according to the present invention, toner dust near the regulating blade is prevented, and toner leakage to the back of the regulating blade is prevented, so that it is possible to efficiently collect deteriorated toner in the toner reservoir. Can be done well.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an image forming apparatus equipped with one embodiment of a developing device according to the present invention.
FIG. 2 is an enlarged cross-sectional view of the developing device of FIG. 1, showing an embodiment of the developing device of the present invention.
FIG. 3 is an enlarged view of a main part of FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 13 ... Toner carrier 16 ... Toner supply body 17 ... Toner storage part 19 ... Toner layer control means 20 ... Toner return path 22 ... Sealing material

Claims (3)

A toner carrier that transports toner to the development position, a toner supplier that supplies toner to the toner carrier, a toner reservoir that transports toner to the toner supplier, and a toner layer thickness of the toner carrier are regulated. Toner layer regulating means, a toner return path formed between a peripheral wall of the developing housing facing the toner supply body below the toner supply body and the surface of the toner supply body, and the toner layer regulating means; A sealant disposed between the developing housing on the side forming the toner return path, and the toner carrier and the toner supply body are both rotated downward at the contact position, and the toner layer regulating means There the toner carrying member and the downstream side in the rotational direction than the contact position between the toner supplying member and said is contact with the counter direction to the toner carrying member at the upstream side of the developing position, the In the developing device the toner passage towards the toner recirculation passage in toner supply member and the toner layer regulating means and said sealing material is formed,
Formed between the tip of the width of the toner passage formed between the surface of the toner supply member and the distal end of the sealing material, the surface and the toner layer regulating means of the toner supply member of the toner passage A developing device characterized in that it is wider than the toner passage and narrower than the smallest portion of the toner recirculation passage. The developing device according to claim 1, wherein the thickness of the tip of the toner layer regulating unit is larger than the thickness of the tip of the sealing material. The developing device according to claim 1, wherein the toner layer regulating unit is conductive.

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