Patent Application
20110222942
Exemplary embodiments described herein relate to a conveying roller, an image forming apparatus, and a conveying method of image formed sheet.
In the image forming apparatus, such as a copy machine and a printer, the conveying roller pair for conveying an image fixed sheet, it is common to press a plastic roller and to make it follow to an image carrying surface side of the sheet where a rubber roller and a toner image were formed in an image non-formation surface side. The sheet is inserted between such pair of the conveying rollers, and the sheet is conveyed.
The sheet is heated in order to fix the toner image in fixing assembly. Therefore, hot the toner image is contacting the sheet immediately after the sheet passing through fixing assembly, and when the toner image contacts the conveying roller, a contact portion will be cooled rapidly. Therefore, there is a possibility of occurring a glossy unevenness between the conveying roller contacting portion and roller non-contacting portion.
Therefore, in order to prevent occurring of the glossy unevenness, it is hoped to diminish contact area of the conveying roller and the sheet contact. It is possible to provide grooves over entire surface of the roller for diminishing contact area to the sheet.
However, when the grooves are provided over whole surface of a roller, the roller does not rotate smoothly due to the surface unevenness, and thus there is a possibility of that problems, such as occurring of noise, may arise.
In general, according to one embodiment, there is provided a conveying roller including: a rotatable first cylindrical portion which is provided with a groove on the surface thereof; a second cylindrical portion which is provided with a groove on the surface thereof, the second cylindrical portion having external diameter the same as that of the first cylindrical portion, and provided on the axis the same as that of the first cylindrical portion outside diameter as the first cylindrical portion; and a third cylindrical portion which is provided with a flat and smooth surface, the third cylindrical portion having an external diameter the same as that of the first and second cylindrical portions, and provided on the axis the same as that of the first and second cylindrical portions between the first and second cylindrical portions.
Hereafter, the embodiments will be described with reference to
An image forming apparatus 1 includes an image reader 4 to read in documents as image data, and an image forming portion 2 to output the image data as visible image. An image forming portion 2 has an image forming unit including, e.g., a drum type photoconductor etc, as will be mentioned later, and a fixing device, etc. Further, the image forming apparatus 1 has a sheet supply unit 3 to supply a sheet P of any size to the image forming portion 2.
An image reader 4 is provided with a light permeable document table 8, a carriage 9, an exposure lamp 10, a reflection mirror 11, an imaging lens 12 for converging reflected light, and a CCD (Charge Coupled Device) 13 for converting image data effected by the reflected light to analog signal.
The image forming apparatus 1 shown in
The image forming unit 15K is provided with a laser unit 17K for forming an electrostatic latent image on a drum-type photoconductor 16K as an image carrier, and devices disposed around the photoconductor 16K one by one, i.e., an electrifying unit 18K, a developing device 19K, a cleaner 22K, and a charge elimination lamp 23K.
As shown in
A document subjected to copy is placed on the document table 8, or a well-known automatic document feeder 30 set on the document table 8. When a copy button (not shown) is operated, the document placed on the document table 8 or conveyed on the document table 8 from the automatic document feeder 30 is exposed with light from an exposure device. The exposure device is constituted by a carriage 9, an exposure lamp 10 provided in carriage 9, reflection mirror 11, and an imaging lens 12. When light is applied to the document from lower portion of the document table 8 by operating the exposure lamp 10, reflected light from the document is guided with a reflection mirror 11, and converged with an imaging lens 12. Then, reflected light image is projected on the CCD 13. Light from the exposure lamp 10 scans the document surface in synchronization with the movement of the carriage 9 (in case of
In image forming portion 2, when image forming starts, electrifying unit 18K applies electric charge on the peripheral surface of photoconductor 16K in rotation, and charges the peripheral surface of photoconductor 16K in uniform electric potential. Next, the laser unit 17K radiates the outer surface of the photoconductor 16K with laser beam modulated with the image data taken in the CCD 13 and then digitized therein. This laser beam scans the drum-type photoconductor along the rotation axis thereof, and forms an electrostatic latent image corresponding to image data on peripheral surface of photoconductor 16K in rotation. Further, developing powder such as toner is applied to the peripheral surface of the photoconductor 16K, and the electrostatic latent image is converted into the toner image, i.e., developed image, by the developing device 19K.
The developing device 19K is provided with a developing roller 24K formed enabling free rotation. By the developing roller 24K rotating in placed in opposite to the photoconductor 16K, toner is applied to photoconductor 16K. When the toner image is formed in peripheral surface of photoconductor 16K, the toner image is electro-statically transferred to the intermediate transfer belt 14 with the primary transfer roller 20K which contacts via the photoconductor 16K and the intermediate transfer belt 14.
Toner on the photoconductor 16K which remained without being transferred is removed from the primary transfer roller 20K by the cleaner 22K located in rotational direction downstream of the photoconductor 16K. Residual charge on the peripheral surface of the photoconductor 16K is removed by the charge elimination lamp 23K. When forming color picture, above-mentioned operation is similarly performed one by one in the image forming units 15Y, 15M, and 15C. Therefore, on the intermediate transfer belt 14, developed image of each color formed with each image forming unit is superimposed, and turns into color picture.
Toner image transferred by the intermediate transfer belt 14 is further transferred electro-statically on the sheet conveyed from the sheet supply unit 3 through a conveying path by the secondary transfer roller 25. Then, the sheet P with which the toner image was transferred is conveyed to fixing device 26, and it is fixed to the toner image transferred on the sheet by the fixing device 26. The sheet which was fixed to the toner image and image forming completed is discharged on a paper tray 28 which is a discharge portion by the conveying roller pair 27 which is a transportation portion of the sheet.
The driven roller 27b of the conveying roller pair 27 is explained in detail.
The third cylindrical portion 104 is formed between the first cylindrical portion 100 and the second cylindrical portion 102. Outside diameter of the third cylindrical portion 104 is equal to the outside diameters of the first cylindrical portion 100 and the outside diameter of the second cylindrical portion 102. Grooves are not provided on the surface of the third cylindrical portion, therefore circumference surface thereof is smooth, and the entire circumference surfaces contacts the sheet.
Thus, by the first cylindrical portion 100 and the second cylindrical portion 102 provided with grooves on their surfaces, contact area with the driven roller 27b with image carrying surface side of the sheet can be reduced. By making the surface of the third cylindrical portion 104 into smooth field, rotation with the rubber drive roller 27a is performed smoothly, and noise does not occur furthermore easily.
When a width dimension of first cylindrical portion 100 in axial direction is set to a, a width dimension of the second cylindrical portion 102 in axial direction is set to b, and a width dimension of the third cylindrical portion 104 in axial direction is set to c, relationships a>c and b>c come into effect. That is, the third cylindrical portion 104 is formed with the width dimension narrower than both the first cylindrical portion 100 and the second cylindrical portion 102. This is for diminishing area of the third cylindrical portion 104 of which entire circumference surface contacts the image carrying surface of the sheet and reducing both contact areas thereof to the sheet and the driven roller 27b.
By executing above-mentioned embodiment, on the occasion of the image fixed sheet being conveyed by the conveying roller generating of a glossy unevenness on the sheet can be prevented. Furthermore, by executing the above-mentioned embodiment, it becomes possible to convey the sheet smoothly.
Although the first cylindrical portion 100 and the second cylindrical portion 102 were provided a plurality of grooves aligning in the circumference direction, but the aligning aspect of the grooves is not limited to the above one. In short, the first cylindrical portion 100 and the second cylindrical portion 102 should just be a structures provided a plurality of grooves 110 in each surface, as contact area with the image carrying surface side of the sheet is reduced. For example, as shown in
A modifications of the groove 110 on the surface of the first cylindrical portion 100 and the second cylindrical portion 102 are shown in
In
Although a plurality of grooves 110 shown in
While certain embodiments have been described, those embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, novel methods and apparatuses described herein may be embodied in variety of other forms; furthermore, various omissions, substitutions and changes in the form of methods and apparatuses described herein may be made without departing from the spirits of the invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and the spirits of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2010-286835 | Dec 2010 | JP | national |
This application is based upon and claims benefit of priority from prior U.S. Patent Application No. 61/312,046, filed on Mar. 9, 2010, entire contents of which are incorporated herein by reference. This application is also based upon and claims benefit of priority from Japanese Patent Application No. 2010-286835, filed on Dec. 24, 2010, entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61312046 | Mar 2010 | US |
