JP2010079264A - Image forming apparatus, developer supply unit, and scattered developer collecting method for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus reducing the scattering of a developer from a developing unit, the developer supply unit, and a scattered developer collecting method for the image forming apparatus. <P>SOLUTION: In a developing sleeve end of a developing unit, an exhaust duct having an opening opened toward a non-printing area of a transfer belt is formed in the developing sleeve turning direction downstream of a nip with a photoreceptor drum. The exhaust duct emits an air flow generated by the rotation of the developing sleeve and the photoreceptor drum from the opening opened toward the non-printing area of a developer carrying face of the transfer belt. The transfer belt electrostatically attracts the emitted scattered developer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that reduces generation of scattered toner from a developer supply unit, a developer supply unit, and a method for collecting scattered developer of an image forming apparatus.

  In an image forming apparatus such as a copying machine, an MFP (Multifunction Peripheral) and a printer, a developer is supplied to a photosensitive drum on which an electrostatic latent image is formed by a developer supply unit. An image is formed.

  The developer supply unit includes a developing sleeve that faces the photosensitive drum. The developing sleeve forms a nip portion with the photosensitive drum by the developer carrying member, and rotates in the opposite direction to the photosensitive drum.

  When the developing sleeve and the photosensitive drum rotate, air flows into the casing of the developer supply unit along the developing sleeve, and the atmospheric pressure in the casing increases. When the atmospheric pressure in the casing increases, the developer carrying member at the end of the developing sleeve is not present, and air is discharged from a portion that does not form a nip with the photosensitive drum, causing the developer to scatter.

  With regard to this point, a technique has been proposed in which a ventilation portion for releasing air is provided at the end of the developing sleeve of the casing of the developer unit, and a filter is provided in the ventilation portion (for example, Patent Document 1).

  In addition, a technique has been proposed in which a negative pressure flow passage communicating with the vicinity of the screw for stirring the developer is provided in the negative pressure generating portion upstream of the developing sleeve rotation direction so that the internal pressure of the casing does not increase (for example, patents). Reference 2).

JP-A-6-202464 JP 2005-258275 A

  However, in the technique described in Patent Document 1, the presence of fine developer passing through the filter cannot be ignored, and in the technique described in Patent Document 2, scattering developer is generated in the downstream direction of the developing sleeve. There is a problem that this cannot be prevented.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus, a developer supply unit, and a scattered developer collecting method for an image forming apparatus that reduce the scattering of the developer from the developing unit.

  In the present invention, a developer supply unit having a developing sleeve for supplying a developer to a photosensitive drum on which an electrostatic latent image is formed, and a developer image of the photosensitive drum formed by the developer can be carried and moved. An image forming apparatus comprising: a movable member; and an exhaust duct that is provided between the developing sleeve and the moving member of the developer supply unit and exhausts from the vicinity of the developing sleeve toward the moving member. To do.

  According to the present invention, there is an effect that the amount of scattered developer generated from the developer supply unit can be reduced.

1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus. FIG. 4 is a cross-sectional view of the vicinity of a developer supply unit. It is a perspective view of a developer supply unit. It is sectional drawing of an exhaust duct at the time of providing a filter in an exhaust duct.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the drawings.

(Outline of image forming apparatus)
FIG. 1 is a schematic diagram showing the configuration of the image forming apparatus according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 includes an automatic document feeder 2, an image reading unit 3, an image forming unit 4, a transfer mechanism 5, a paper transport mechanism, a paper feeding unit 6, and a fixing unit. 7, a reverse conveyance mechanism 8, and a discharge mechanism 9.

  The automatic document feeder 2 is installed at the top of the main body of the image forming apparatus 1 so as to be openable and closable. The automatic document feeder 2 includes a document conveyance mechanism that takes out documents one by one from the document tray and conveys them to the paper discharge tray.

  The automatic document feeder 2 conveys documents one by one to the document reading unit of the image reading unit 3 by the document conveying function. It is also possible to open the automatic document feeder 2 and place the document on the document table of the image reading unit 3.

  The image reading unit 3 includes an exposure lamp that exposes a document and a carriage including a reflection mirror, a plurality of reflection mirrors installed on a main body frame of the image forming apparatus 1, a lens block, and a CCD (Charge Coupled Device) of the image reading sensor. And).

  The carriage rests on the document reading unit or reciprocates under the document table to reflect the light of the exposure lamp reflected by the document to the lens block via a plurality of reflection mirrors. The lens block scales the reflected light and outputs it to the CCD. The CCD converts incident light into an electrical signal and outputs it as an image signal to the image forming unit 4.

  The image forming unit 4 includes a laser irradiation unit, a photosensitive drum, and a developer supply unit 10.

  The laser irradiation unit irradiates the photosensitive drum with laser light based on the image signal to form an electrostatic latent image on the photosensitive drum. The developer supply unit supplies the developer to the photosensitive drum and forms a developer image from the electrostatic latent image.

  The paper feed unit 6 takes out the recording medium P one by one from the paper feed cassette 6a and delivers it to the paper transport mechanism. The paper transport mechanism transports the recording medium to the transfer mechanism 5. The transfer mechanism 5 includes a moving member and a transfer roller. The moving member can carry and move the developer image of the photosensitive drum formed by the developer. A transfer belt as an example of the moving member transfers and carries the developer image on the photosensitive drum. The transfer roller applies a voltage to transfer the developer image on the transfer belt to the recording medium P that has been conveyed.

  After the developer image is transferred to the recording medium on the transfer belt, the remaining developer is scraped off by the cleaning mechanism.

  The fixing unit 7 heats and pressurizes the developer image to fix it on the recording medium P.

  In the single-side mode, the recording medium P having the developer fixed on one side is discharged through the discharge mechanism 9. In the double-sided printing mode, the recording medium P having the developer fixed on one side is conveyed to the image forming unit 4 via the reverse conveying mechanism 8 to form an image in the same manner as described above, and the transfer mechanism 5. The paper is discharged through the fixing unit 7 and the discharge mechanism 9.

(Developer supply unit)
FIG. 2 is a cross-sectional view of the vicinity of the developer supply unit 10. FIG. 3 is a perspective view of the developer supply unit 10. As shown in FIGS. 2 and 3, the developer supply unit 10 is disposed to face the photosensitive drum 11, and develops by developing the developer sleeve 13 that rotates in the opposite direction to the photosensitive drum 11, and stirring the developer. A stirring screw 16 supplied to the sleeve 13 and an exhaust duct 15 are provided.

  The photosensitive drum 11 has a charging device 14 and a portion irradiated with the laser light L upstream in the rotation direction.

  In the case of the two-component system, the developing sleeve 13 is connected to the photosensitive drum 11 and the nip portion by a developer carrier and a developer in the case of the one-component system (hereinafter, both are referred to as a developer). Form.

  The exhaust duct 15 is provided between the vicinity of the developing sleeve 13 of the developer supply unit 10 and the transfer belt 12 as a moving member, and exhausts from the vicinity of the developing sleeve 13 toward the transfer belt 12.

  The exhaust duct 15 is provided in the casing of the developer supply unit 10 downstream of the developing sleeve 13 in the rotational direction nip. The air pressure is high in this portion because air entrained by the rotation of the photosensitive drum 11 and the developing sleeve 13 is discharged.

  The exhaust duct 15 is provided at the end of the developing sleeve 13 of the casing of the developer supply unit 10. At this end, since the magnetic material of the developing sleeve 13 does not exist, the developer layer is thin and a gap is formed between the end and the photosensitive drum 11. The exhaust duct 15 is desirably provided at both ends of the developing sleeve 13 of the casing of the developing unit.

  The exhaust duct 15 has an opening that opens toward the transfer belt 12. The exhaust duct 15 has an opening that opens toward a non-printing area that is a part other than the printing area of the transfer surface of the transfer belt 12, that is, the developer carrying surface. The part other than the printing area is a part other than the area where the developer image is transferred, for example, both ends in the width direction of the transfer belt.

  An air flow is generated at both ends of the developing sleeve 13 by the atmospheric pressure increased by the rotation of the photosensitive drum 11 and the developing sleeve 13. This air flow generates scattered developer. The exhaust duct 15 allows this air flow to escape to the transfer surface of the transfer belt 12. The transfer belt 12 is electrostatically positively charged. On the other hand, the developer is negatively charged. Accordingly, the scattered developer is adsorbed on the non-printing area of the transfer belt 12. The adsorbed developer is scraped off by the cleaning mechanism.

  FIG. 4 is a cross-sectional view of the exhaust duct 15 when the filter 17 is provided in the exhaust duct 15. As shown in FIG. 4, a filter 17 may be provided in a part of the exhaust duct 15. The filter 17 is provided in the middle of the air flow path of the exhaust duct 15. The filter 17 can further reduce the scattered developer.

  As described above, the image forming apparatus 1 according to this embodiment includes the transfer belt at the end of the developing sleeve 13 of the casing of the developer supply unit 10 and the downstream of the developing sleeve rotation direction of the nip portion with the photosensitive drum 11. The exhaust duct 15 has an opening that opens toward the 12 non-printing areas. Therefore, the scattered developer generated by the airflow generated by the rotation of the developing sleeve 13 and the photosensitive drum 11 is collected by the transfer belt 12 by static electricity, and the generation of the scattered developer can be reduced.

10: Developer supply unit,
11: Photosensitive drum,
12: transfer belt,
13: Development sleeve,
15: exhaust duct,
17: Filter.

Claims (7)

A developer supply unit having a developing sleeve for supplying the developer to the photosensitive drum on which the electrostatic latent image is formed;
A movable member capable of carrying and moving a developer image of the photosensitive drum formed by the developer;
An exhaust duct that is provided between the developing sleeve and the moving member of the developer supply unit, and exhausts from the vicinity of the developing sleeve toward the moving member;
An image forming apparatus comprising: The developer supply unit includes:
The image forming apparatus according to claim 1, wherein the exhaust duct is provided downstream of a nip portion of the casing with the photosensitive drum in the developing sleeve rotation direction. The developer supply unit includes:
The image forming apparatus according to claim 1, wherein the exhaust duct is provided in the casing such that an opening is opened toward a non-printing area of the developer carrying surface of the moving member. The developer supply unit includes:
The image forming apparatus according to claim 1, further comprising the exhaust duct having a filter in the middle of the air flow path. A developing sleeve that is disposed opposite to the photosensitive drum carrying the electrostatic latent image and forms a nip portion;
A stirring screw that stirs the developer and supplies it to the developing sleeve;
An exhaust duct having an opening opening toward the moving member at the end of the developing sleeve of the casing;
A developer supply unit.   The exhaust duct is provided in the casing so as to open toward the non-printing area of the developer carrying surface of the moving member downstream of the nip portion with the photosensitive drum in the rotation direction of the developing sleeve. The developer supply unit according to claim 5. The exhaust duct exhausts the airflow generated by the rotation of the developing sleeve and the photosensitive drum from an opening that opens toward the non-printing area of the developer carrying surface of the moving member,
A method for collecting scattered developer of an image forming apparatus, wherein a moving member electrostatically adsorbs the discharged scattered developer.

Images