JPH09265219A - Transfer-paper carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent partial wear of a fixing roller and to prolong its life. SOLUTION: In a transfer-paper carrying mechanism 17 for carrying transfer paper 4, sent from a transfer unit 13, to a fixing unit 16 consisting of the fixing roller 25 and a pressure roller 26 being in pressure contact with each other, a skew mechanism 27 for skewing the transfer paper 4 at a specific angle is provided. Therefore, when the transfer paper 4 passes along the fixing roller 25, the transfer paper 4 is carried while the place where the edges of the transfer paper 4 are in contact with the fixing roller 25 is moved to the axial direction of the fixing roller 25. As a result, the area where the edges of the transfer paper 5 are in contact with the fixing effective area of the fixing roller 25 can be continuously altered. Therefore, prevents partial wear of the fixing roller 4 and extends its life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer paper carrying device for carrying a transfer paper to a fixing device in an electrophotographic apparatus.

[0002]

2. Description of the Related Art A fixing device used in an electrophotographic apparatus is a process in which a transfer paper on which an image formed on an image carrier is transferred by a transfer device is conveyed while being held by a fixing roller and a pressure roller. A type of fixing a transfer image on a transfer paper is often used. In such a fixing device, in order to prevent the image transfer surface of the transfer paper from wrapping around the fixing roller, the surface of the fixing roller is subjected to a treatment for improving the peelability of the transfer paper, and An oil such as silicone oil is applied as a release agent, and the edge of the peeling claw is in contact with the fixing roller.

However, at least the effective fixing area of the fixing roller is often formed of an elastic member such as rubber, and that portion is easily worn. In the case of the transfer paper having the maximum width or less, the edge portion always passes through the fixing effective area, so that the surface of the fixing effective area is worn due to contact with the edge of the transfer paper after long-term use. As this wear progresses, the surface of the fixing roller is scratched in a streak pattern in the circumferential direction, oil enters the scratched portion, and the oil stains both sides of the transfer paper.

From the above, Japanese Patent Laid-Open No. 2713/1991
As described in Japanese Patent Publication No. 77, a fixing device has been proposed in which a worn portion of the fixing roller is dispersed by moving the fixing roller in the axial direction. Specifically, the fixing roller is supported movably in the axial direction within a certain range, and both ends of the pressure roller are urged toward the fixing roller side by springs so that the pressure contact force of the pressure roller at both ends of the fixing roller is The fixing roller is displaced in the axial direction by the difference.

[0005]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2-27137
In the fixing device described in Japanese Patent Publication No. 7, the fixing roller moves in the axial direction in the direction in which the pressure contact force of the pressure roller with respect to the fixing roller is small, so the fixing roller cannot be stopped midway. That is, the position of the ring-shaped scratch that wears along the circumferential direction on the outer circumference of the fixing roller due to the contact with the edge of the transfer sheet only changes at intervals corresponding to the moving range of the fixing roller. The points cannot be dispersed continuously. Therefore, there is a limit in extending the life of the fixing roller.

[0006]

According to the first aspect of the present invention,
A transfer device that transfers the image formed on the surface of the image carrier to a transfer paper, a fixing roller, and a pressure roller that is in pressure contact with the fixing roller, and transfers the transfer image on the transfer paper that has passed through the transfer device. A fixing device for fixing, a transfer paper transport mechanism for transporting the transfer paper from the transfer device to the fixing device, and a skewing mechanism arranged in the transfer paper transport mechanism for skewing the transfer paper by a predetermined angle. Prepare Therefore, when one sheet of transfer paper passes through the fixing roller, the edge of the transfer paper is conveyed while moving the contact position with the fixing roller in the axial direction of the fixing roller, so that the transfer to the fixing effective area of the fixing roller is performed. The contact area at the edge of the paper changes continuously.

According to a second aspect of the present invention, in the first aspect of the invention, the skew feeding mechanism includes a switching portion that selectively switches the skew feeding direction of the transfer sheet to a symmetrical direction. Therefore, the contact portion of the edge of the transfer paper with respect to the effective fixing area of the fixing roller continuously changes. Further, the direction of the transfer paper discharged from the fixing roller is changed by the switching operation of the switching unit.

According to a third aspect of the present invention, in the first or second aspect of the invention, the skew feeding mechanism is maintained in a stopped state when it is recognized that the width of the transfer sheet is the maximum width. That is, in consideration of the left and right margins, it is possible for the transfer paper of the maximum width to pass outside the fixing effective area where the edge portion is easily worn. Therefore, by not skewing the transfer paper, the entire length of the fixing roller can be prevented. There is no need to make the length longer than necessary.

[0009]

An embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows the overall structure of the electrophotographic apparatus. 1 is an apparatus main body. A transfer belt 2 which is driven in the vertical direction is provided at the center of the apparatus main body 1.
Image forming units 3 that form images of different colors are arranged along the rotation direction of the transfer belt 2. On the outside of the apparatus main body 1, a sheet feeding unit 5 that feeds the stacked transfer sheets 4 one by one, and a double-sided sheet feeding unit that re-feeds the printed transfer sheets 4 when the double-sided printing mode is designated. 6, a paper discharge tray 7 is provided. The device body 1
A transfer path 8 for transferring the transfer paper 4 from the paper supply unit 5 and the double-sided paper supply unit 6 toward the lower part of the transfer belt 2 is provided in the paper.

The image forming section 3 charges the surface of the image carrier 9 by the charger 10, and the charged portion is charged by the optical writer 1.
1, a laser beam is scanned to form an electrostatic latent image, the electrostatic latent image is developed by the developing device 12, and the developed image on the image carrier 9 is transferred to the transfer paper 4 conveyed by the transfer belt 2. After transfer by the device 13, the image bearing member 9 is removed from the charge eliminating lamp 1.
It is a structure for removing the electric charge by 4.

On the upper part of the apparatus main body 1, a separation charger 1 for separating the transfer paper 4 from the upper part of the transfer belt 2.
5, a transfer sheet conveying mechanism 17 that conveys the transfer sheet 4 separated from the transfer belt 2 to the fixing device 19, discharge rollers 18 and 19 that discharge the transfer sheet 4 that has passed through the fixing device 16, and the discharge roller 1
The transfer paper 4 ejected by means of the double-sided paper feeding unit 6
A rotatable switching claw 21 that selectively guides the passage 20 communicating with the sheet discharge tray 7 and the discharge tray 7 is provided. A heater 2 is provided above the transfer paper transport mechanism 17 in order to improve fixing efficiency.
A preheating device 24 including two and a fan 23 is provided. The fixing device 16 is composed of a fixing roller 25 and a pressure roller 26 that is pressed against the fixing roller 25. Further, the transfer paper transport mechanism 17 is provided with a skewing mechanism 27 for skewing the transfer paper 4 by a predetermined angle.

As shown in FIGS. 2 and 3, the transfer sheet conveying mechanism 17 includes a guide plate 28a for supporting the transfer sheet 4 and a side fence 28 whose position is adjusted in the width direction of the transfer sheet 4.
And a plurality of transport rollers 29 driven by a motor (not shown). The skew mechanism 27 includes two roller shafts 30 and 31 that are orthogonal to the transport roller 29 at approximately the center of the separation space of the side fence 28, and ends of these roller shafts 30 and 31 in opposite directions. The fixed skew rollers 32 and 33, the gears 34 and 35 fixed to the intermediate portions of the roller shafts 30 and 31 and meshed with each other, and the forward and reverse rotatable motors (not shown) are connected to the roller shafts. The drive transmission member 36 fixed to the end of the sheet 30, and the transfer paper 4
And a sensor 37 that outputs a signal for driving the motor to rotate the drive transmission member 36 once when detecting the tip of the. As shown in FIG. 4, the skew rollers 32 and 33 have a D-shape with a part of the outer circumference cut out, and normally, the cut rollers are stationary with the cut-out parts facing upward, and the transfer paper 4 Never touch.

In such a structure, the transfer paper 4 conveyed by the transfer belt 2 and passing through the image forming section 3 is conveyed to the fixing device 16 by the transfer paper conveying mechanism 17. At this time, when the sensor 37 detects the front end of the transfer paper 4, the motor rotates and the drive transmission member 36 makes one rotation together with the roller shaft 30 and the skew roller 32. Since the rotation of the roller shaft 30 is transmitted to the roller shaft 31 by the gears 34 and 35, the skew roller 33 rotates once in the direction opposite to the skew roller 32. That is, since the upstream side portion of the transfer paper 4 is moved downward in FIG. 2 and the downstream side portion thereof is moved upward in FIG. 2, the transfer paper 4 is inclined from the straight state shown by the solid line as shown by the dotted line. In this state, it is conveyed to the fixing device 16 by the conveying roller 29. The inclination angle of the transfer paper 4 at this time is regulated by the side fence 28 whose position is adjusted in the width direction of the transfer paper 4 according to the size of the transfer paper 4.

As a result, as shown in FIG.
Is a range of a dimension (hatched range) in which the contact portion of the edge of the transfer paper 4 with respect to the effective fixing area (not shown) of the fixing roller 25 when passing through the fixing roller 25 is a in the axial direction of the fixing roller 25. ) Only changes continuously. Therefore, the fixing roller 25 is not locally worn, and the life can be extended. This is an effect corresponding to the first aspect of the present invention.

In this case, if the inclination of the transfer paper 4 is too large, the entire length of the fixing roller 25 must be lengthened, so about 1 ° to 5 ° is appropriate. 420m long side
For example, when using the A4 size transfer paper 4 of m, the inclination angle is 3 °.
And a in FIG. 5 is slightly less than 22 mm.

When the rotation direction of the motor is changed and the rotation direction of the drive transmission member 36 is reversed, the skew rollers 32 and 3 are rotated.
Since the rotation direction of 3 is changed, as shown in FIG. 6, the oblique direction of the transfer paper 4 can be switched to the symmetrical direction. Thereby, when the printed transfer sheet 4 is discharged to the discharge tray 7, the direction of the transfer sheet 4 discharged from the fixing roller 25 can be changed. Along with this, it is possible to use the two types of printed matter separately on the one discharge tray 7 and stack them. This is an effect corresponding to the second aspect of the invention. That is, the drive transmission member 36 is the transfer paper 4
Function as a switching unit that selectively switches the skew direction of the to the symmetrical direction.

Further, although the size of the transfer paper 4 is designated by an operation unit (not shown) or detected by a size detector (not shown), as shown in FIG. When the transfer sheet 4S is recognized as the sheet 4S, the transfer sheet 4S is tilted by the skew feeding mechanism 27 as described above, but when the transfer sheet 4L having the maximum width is recognized, the left and right margins are considered. Since it is also possible to pass the edge portion outside the effective fixing area where it is easily worn, the skew feeding mechanism 2
By stopping No. 7, it is not necessary to extend the entire length of the fixing roller 25 more than necessary, which can contribute to downsizing of the apparatus. This is an effect corresponding to the third aspect of the present invention. In this case, the maximum width of the transfer paper 4L
It is desirable to wind an abrasion resistant sheet thinner than the transfer paper 4 around the portion of the fixing roller 25 through which the sheet passes.

[0018]

According to the first aspect of the present invention, there is provided a transfer device for transferring the image formed on the surface of the image carrier onto a transfer sheet, a fixing roller, and a pressure roller pressed against the fixing roller. A fixing device for fixing the transferred image on the transfer paper that has passed through the transfer device, a transfer paper transport mechanism for transporting the transfer paper from the transfer device to the fixing device, and a transfer paper transport mechanism arranged in the transfer paper transport mechanism. Since the transfer paper has a skewing mechanism for skewing the transfer paper at a predetermined angle, when one transfer paper passes through the fixing roller, the edge of the transfer paper moves the contact position with the fixing roller in the axial direction of the fixing roller. Since the sheet is conveyed while being moved, the contact portion of the edge of the transfer sheet with respect to the effective fixing area of the fixing roller can be continuously changed. Therefore, it is possible to prevent local wear of the fixing roller and extend the life of the fixing roller.

According to a second aspect of the present invention, in the first aspect of the present invention, the skew feeding mechanism includes a switching unit that selectively switches the skew feeding direction of the transfer sheet to a symmetrical direction. As in the invention described above, the life of the fixing roller can be extended, and further, the direction of the transfer paper discharged from the fixing roller can be changed by the switching operation of the switching unit, so that two types of printed matter can be obtained. It can be used by loading separately on one output tray.

According to a third aspect of the invention, in the first or second aspect of the invention, the skew feeding mechanism is maintained in a stopped state when it is recognized that the width of the transfer sheet is the maximum width.
Considering the left and right margins, when using a transfer paper of the maximum width that allows the edge to pass outside the fixing effective area where it is easily worn, keep the skewing mechanism in a stopped state and skew the transfer paper. It can be conveyed to the fixing device without being carried out. This eliminates the need for making the total length of the fixing roller longer than necessary and can contribute to downsizing of the apparatus.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an overall structure of an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing a transfer sheet conveying mechanism and a skew feeding mechanism.

FIG. 3 is a side view showing a transfer sheet conveying mechanism and a skew feeding mechanism.

FIG. 4 is a rear view of the skew feeding mechanism.

FIG. 5 is a plan view showing a relationship between a fixing roller and a transfer sheet.

FIG. 6 is a plan view showing a state in which a transfer sheet is tilted in a symmetrical direction.

FIG. 7 is a plan view showing a relationship between a fixing roller and a transfer sheet.

[Explanation of symbols]

 4 Transfer Paper 9 Image Carrier 13 Transfer Device 16 Fixing Device 17 Transfer Paper Conveying Mechanism 25 Fixing Roller 26 Pressure Roller 27 Skewing Mechanism 36 Switching Unit

Claims (3)

[Claims] 1. A transfer device having a transfer device for transferring an image formed on a surface of an image carrier onto a transfer sheet, a fixing roller and a pressure roller pressed against the fixing roller, and passing through the transfer device. A fixing device for fixing the transfer image on the paper, a transfer paper transport mechanism for transporting the transfer paper from the transfer device toward the fixing device, and a transfer paper arranged in the transfer paper transport mechanism to skew the transfer paper at a predetermined angle. A transfer paper transporting device comprising a skewing mechanism. 2. The transfer sheet conveying device according to claim 1, wherein the skew feeding mechanism includes a switching unit that selectively switches a skew feeding direction of the transfer sheet to a symmetrical direction. 3. The transfer sheet transporting device according to claim 1, wherein the skew feeding mechanism is maintained in a stopped state when recognizing that the width of the transfer sheet is the maximum width.