1. Field of the Invention
The present invention relates to an image forming apparatus including, in a secondary transfer unit having a mechanism for bringing a secondary transfer roller into contact with and separating the secondary transfer roller from an image bearing member, a mechanism for further bringing the secondary transfer roller into contact with and separating the secondary transfer roller from a fur brush and an image forming method therefor.
2. Description of the Related Art
A transfer device includes a contact and separation mechanism for bringing a secondary transfer roller into contact with an image bearing member when the transfer device transfers a toner image formed on the image bearing member onto a sheet and separating the secondary transfer roller from the image bearing member when the transfer device does not transfer the toner image onto the sheet.
There is known a contact and separation driving device for a secondary transfer roller in which, in a secondary transfer unit having a mechanism for bringing a secondary transfer roller into contact with and separating the secondary transfer roller from an image bearing member, the number of components of a mechanism unit configuring the mechanism for performing a contact and separation operation is not increased and a device such as an electromagnetic clutch that requires electric control is not used (JP-A-2007-264546).
An image forming apparatus according to a first aspect of the present invention includes an image transfer unit that transfers a reversed image based on a scanned original image onto an image bearing member as a toner image, a secondary transfer roller that comes into contact with the image bearing member and transfers the toner image onto a recording medium, a contact and separation unit that brings the secondary transfer roller into contact with and separates the secondary transfer roller from the image bearing member, a secondary-transfer-roller housing unit that houses the secondary transfer roller, a lubricant applying brush that comes into contact with the secondary transfer roller and applies a lubricant thereto, a lubricant-applying-blush housing unit that houses the lubricant applying brush and is configured to be movable along a groove provided in the secondary-transfer-roller housing unit, and an lifting and lowering member that is provided in another member not associated with the secondary-transfer-roller housing unit and lifts and lowers the lubricant-applying-brush housing unit, wherein the secondary transfer roller and the lubricant applying brush come into contact with and separate from each other in response to a contact and separation operation of the secondary transfer roller and the image bearing member.
An image forming method according to a second aspect of the present invention is an image forming method for an image forming apparatus including an image transfer unit configured to transfer a reversed image based on a scanned original image onto an image bearing member as a toner image, a secondary transfer roller that comes into contact with the image bearing member and transfers the toner image onto a recording medium, and a contact and separation unit configured to bring the secondary transfer roller into contact with and separate the secondary transfer roller from the image bearing member, comprising: contacting the secondary transfer roller and a lubricant applying brush with and separating from each other in response to a contact and separation operation of the secondary transfer roller and the image bearing member,
wherein the image forming apparatus includes a secondary-transfer-roller housing unit configured to house the secondary transfer roller, the lubricant applying brush that comes into contact with the secondary transfer roller and applies a lubricant thereto, a lubricant-applying-blush housing unit configured to house the lubricant applying brush and to be movable along a groove provided in the secondary-transfer-roller housing unit, and an lifting and lowering member that is provided in another member not associated with the secondary-transfer-roller housing unit and lifts and lowers the lubricant-applying-brush housing unit.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
As shown in
The laser unit 12 irradiates a laser beam optically modulated according to an image signal of an original scanned by a not-shown scanner unit or an image signal inputted from an external apparatus and forms electrostatic latent images on the developing devices 14. The developing devices 14 reversely develop the electrostatic latent images and transfer toner images onto the transfer belt 16.
The sheet conveying path 18 is a conveying path for a sheet fed from a not-shown paper feeding unit.
The registration rollers 20 correct inclination of the sheet immediately before an image is transferred thereon. The secondary transfer roller 22 is arranged downstream of the registration rollers 20 and opposed to the counter roller 17 to be capable of coming into contact with the transfer belt 16. When the sheet passes between the transfer belt 16 and the secondary transfer roller 22, the toner images are collectively transferred onto the sheet. The conveyance guide 24 guides the sheet, which is conveyed out from the secondary transfer roller 22, to the fixing device 26. The fixing device 26 fixes an image transferred by the secondary transfer roller 22 on the sheet.
As shown in
A bearing of the secondary transfer roller 22 is held by a secondary-transfer-roller holding case 45. The secondary-transfer-roller holding case 45 has a guide groove 46 for guiding the fur brush unit 42 up and down. In the fur brush unit 42, two shafts are provided on each of a front side and a rear side of the secondary transfer unit. The two shafts provided on each of the front side and the rear side move up and down along the guide groove 46, whereby the fur brush unit 42 is capable of moving up and down.
As shown in
Pushers 32 are disposed near lower ends 28a of the lever-like members 28, respectively. Distal ends 32a of the pushers 32 press the lower ends 28a of the lever-like members 28, whereby the lever-like members 28 swing against the elastic force of the springs. Consequently, the secondary transfer roller 22 can be separated from the transfer belt 16. On the other hand, the distal ends 32a of the pushers 32 separate from the lever-like members 28, whereby the lever-like members 28 swing with the elastic force of the springs to positions for bringing the secondary transfer roller 22 into contact with the transfer belt 16.
The entire secondary transfer unit is supported by a secondary-transfer-unit holding frame 47. A fulcrum 48 is provided in an upper part of the secondary-transfer-unit holding frame 47. The fulcrum 48 is connected to the secondary-transfer-roller holding case 45. Therefore, the secondary-transfer-roller holding case 45 can rotate around the fulcrum 48. A not-shown sheet metal is provided in the secondary-transfer-roller holding case 45. As described above, the pushers 32 push the sheet metal, whereby the secondary-transfer-roller holding case 45 swings between the first position and the second position with the fulcrum 48 as a rotation axis.
A rack 49 is provided below the fur brush unit 42. Two compression springs 50a and 50b (compression springs 50) are attached between the rack 49 and the fur brush unit 42. The compression springs 50a and 50b press the fur brush unit 42.
Operations of the fur brush unit 42 during the contact and separation operation are explained.
During the separation, the fur brush unit 42 is pushed up by the compression springs 50 provided in the rack 49 and comes into contact with the secondary transfer roller 22. The fur brush unit 42 moves up and down along the guide groove 46. Therefore, a position where an upper shaft 52a comes into contact with an upper end of the guide groove 46 is an upper limit position of the operation.
As shown in
During transition from a separation state shown in
As a position of contact of the cylindrical member 53 and the slope of the lifting and lowering member 54 moves, the fur brush unit 42 is pushed downward. Therefore, at a point when this contact operation is completed, the fur brush unit 42 and the secondary transfer roller 22 are separated from each other.
According to the progress of the contact operation, the cylindrical member 53 changes the position of contact with the lifting and lowering member 54 while rotating around the lower shaft 52b. Therefore, the fur brush unit 42 smoothly moves downward without being affected by an unnatural force. The lower shaft 52b and the lifting and lowering member 54 do not come into direct contact with each other. A material (synthetic resin) of the cylindrical member 53 is softer than a material (metal) of the lifting and lowering member 54 and the lower shaft 52b. Therefore, there is little abrasion between the lower shaft 52b and the lifting and lowering member 54 and it is possible to consume only the cylindrical member 53.
During transition from the contact state shown in
In the first embodiment explained above, the fur brush 40 separates from the secondary transfer roller 22 when the secondary transfer roller 22 comes into contact with the transfer belt 16. The fur brush 40 comes into contact with the secondary transfer roller 22 when the secondary transfer roller 22 separates from the transfer belt 16. As a result, compared with the system in the past in which the fur brush 40 is always in contact with the secondary transfer roller 22, it is possible to prevent the lubricant from being excessively applied to the secondary transfer roller 22.
In a second embodiment of the present invention, a contact and separation operation of the secondary transfer roller 22 and the fur brush 40 and a mechanism therefor are different from those in the first embodiment. Therefore, components identical with those in the first embodiment are denoted by the same reference numerals and signs and explanation of details of the components is omitted.
The entire secondary transfer unit is supported by the secondary-transfer-unit holding frame 47. The fulcrum 48 is provided in the upper part of the secondary-transfer-unit holding frame 47. The fulcrum 48 is connected to the secondary-transfer-roller holding case 45. Therefore, the secondary-transfer-roller holding case 45 can rotate around the fulcrum 48. The not-shown sheet metal is provided in the secondary-transfer-roller holding case 45. As described above, the pushers 32 push the sheet metal, whereby the secondary-transfer-roller holding case 45 swings between the first position and the second position with the fulcrum 48 as a rotation axis.
Leaf spring members (hereinafter referred to as lifting and lowering members) 56a and 56b (lifting and lowering members 56) are provided on a front side and a rear side below the fur brush unit 42. The lifting and lowering members 56a and 56b are attached to the pre-transfer guide 44. When the secondary transfer roller 22 comes into contact with the transfer belt 16, the lifting and lowering members 56a and 56b press the fur brush unit 42.
The lifting and lowering member 56 includes an attaching section 57, an intermediate section 58, and a distal end section 59. A hole for inserting a member for connecting the lifting and lowering member 56 to the pre-transfer guide 44, for example, a bolt is provided in the attaching section 57. The intermediate section 58 is folded in two stages and has two areas. An area close to the distal end section 59 of the intermediate section 58 and the fur brush unit 42 come into contact with each other. The intermediate section 58 is folded in two stages in order to effectively show a function of the leaf spring by setting a contact angle of the intermediate section 58 and the fur brush unit 42 to a predetermined angle. Therefore, the number of folding stages is not limited to two and may be three or more. In other words, two or more areas may be formed in the intermediate section 58.
A boss 60 as a projecting section is formed in the distal end section 59. When the fur brush unit 42 comes into contact with the intermediate section 58, the boss 60 and the pre-transfer guide 44 come into contact with each other, whereby the lifting and lowering member 56 functions as the leaf spring and presses the fur brush unit 42 upward. A shape of the boss 60 is a spherical surface such that the boss 60 and the pre-transfer guide 44 come into contact with each other at one point. However, since the contact of the boss 60 and the pre-transfer guide 44 only has to be a point contact, the shape of the boss 60 is not limited to the spherical surface and only has to be a shape of a convex curved surface.
Operations of the fur brush unit 42 during the contact and separation operation are explained.
During the separation, the fur brush unit 42 is in a non-contact state with the lifting and lowering member 56. During transition from the separation state shown in
Then, the lifting and lowering member 56 is pressed and the boss 60 and the pre-transfer guide 44 come into contact with each other, whereby the lifting and lowering member 56 functions as the leaf spring and presses the fur brush unit 42 upward. As a result, the fur brush unit 42 is pushed up and comes into contact with the secondary transfer roller 22.
In this way, the lifting and lowering member 56 approaches to come into contact with the pre-transfer guide 44 while bending during the contact of the secondary transfer roller 22. However, after the boss 60 and the pre-transfer guide 44 come into contact with each other, the lifting and lowering member 56 receives a reaction from the pre-transfer guide 44 and deformation of the leaf spring is controlled. Since the reaction is received from the pre-transfer guide 44, a stress is prevented from being concentratedly exerted on the leaf spring.
As a position of contact of the fur brush unit 42 and the intermediate section 58 of the lifting and lowering member 56 moves, the fur brush unit 42 is pushed upward. At a point when this contact operation is completed, the fur brush unit 42 and the secondary transfer roller 22 are in contact with each other.
During transition from the contact state shown in
In the second embodiment explained above, the fur brush 40 comes into contact with the secondary transfer roller 22 when the secondary transfer roller 22 comes into contact with the transfer belt 16. The fur brush 40 separates from the secondary transfer roller 22 when the secondary transfer roller 22 separates from the transfer belt 16.
In the related art in which the fur brush 40 is always in contact with the secondary transfer roller 22, problems described below are pointed out. When recording paper causes jamming or when the recording paper is not supplied because of paper empty or the like, the secondary transfer roller 22 continues to rotate with a transferred toner kept applied thereto. In such a case, it is possible to clean the secondary transfer roller 22 to a certain degree by the cleaning blade 43. However, when the toner remains, the toner soils the fur brush 40 that is always in contact with the secondary transfer roller 22. In the second embodiment, such soiling of the fur brush 40 can be prevented.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
This application is based upon and claims the benefit of U.S. Provisional Applications No. 60/940,254, filed May 25, 2007; and No. 60/969,587, filed Aug. 31, 2007.
Number | Date | Country | |
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60940254 | May 2007 | US | |
60969587 | Aug 2007 | US |