JPH0477312B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sheet separating device for a copying machine after transfer, and more particularly to a sheet separating device including a separating belt, a separating roller, and a deflecting roller.

Prior Art A sheet separating device in which a long and narrow belt-like separating member is arranged along one end edge of a photoreceptor so that the side edge of the sheet moves on it, thereby separating the sheets, was disclosed in Japanese Patent Application Laid-open No. It is known from Publication No. 50-29044. Although this sheet separation device is preferable because it eliminates the need for electrostatic separation, pneumatic separation, etc., it has the disadvantage that the peeling force during separation is weak.

Japanese Patent Laid-Open No. 51-88233 provides a separation belt along the side edge of a photoreceptor, and also includes a separation roller that applies a strong peeling force to the sheet on the belt and a deflection roller that regulates the posture of the sheet after separation. A sheet separating device is disclosed. This sheet separation device is preferable because it has sufficient peeling force, but since the peeling force is different between the side with the separation roll and the side without the separation roll, a slight speed difference occurs in the transfer area, resulting in The problem was that the image was distorted.

These problems will be explained with reference to FIGS. 1 to 3, which show devices that have already been proposed but are not included in the above-mentioned publication. A transfer corona discharger 2 is provided in the transfer area of the photoreceptor 1, and the sheet 3 is fed so as to come into contact with the photoreceptor 1 in this transfer area, and the sheet 3 after transfer is transferred to a sheet separation device 4.
is separated and sent to the guide plate 5, where it is fixed. The sheet separating device 4 includes a separating belt 6 arranged so that the side edge of the sheet 3 moves along one end edge of the photoconductor 1, and a separating belt 6 that separates the sheet 3 on the belt.
a separation roller 7 that contacts the side edge of the photoreceptor 1 and rotates to separate the sheet 3 from the photoreceptor 1;
coaxially juxtaposed to and rotating with the roller;
The separation roller 7 includes a pinch roller 9.
are arranged to face each other, and a guide pin 10 for deflecting the belt 6 so as to press it against the separation roller 7 is provided.

FIG. 2 shows how sheets 3 are separated using such a sheet separating device. As can be seen from this figure, the sheet 3 separated by the separation roller 7 is advanced along the separation roller 7 at the end on the separation roller 7 side; As the distance from the sheet increases, the peeling force of the sheet decreases, and the advancing speed of the sheet slows down, albeit slightly, and the leading edge of the sheet rises as shown by the solid line. Of course, if the sheet is advanced further, the sheet will be advanced along the deflection roll 8 as shown by the two-dot chain line, but while the leading edge of the sheet is rising, the sheet will shift and the transfer area In this case, transfer deviation occurs and the image becomes distorted. As shown in Fig. 3, the distortion of this image is caused by the diameter a of both rollers,
b is the same, and the deflecting roller 8 does not provide sufficient feeding force and the feeding speed is slightly slower than that of the separating roller. This is thought to be due to the fact that the peeling point of the sheet is different from the edge and that there is no means to quickly make the sheet follow the guide plate.

In order to eliminate this drawback, there are some systems in which the contact width of the separation belt with the paper is increased, but the effective width of the photoreceptor becomes narrower, or if the effective width of the photoreceptor is increased, the device becomes larger. There are drawbacks. Apart from this, there are also devices in which the deflection angle during sheet separation is reduced, but this increases the space occupied by the sheet feeding path, which has the disadvantage of increasing the size of the device.

OBJECT OF THE INVENTION Accordingly, an object of the present invention is to provide a system that can be used without increasing the size of the device or narrowing the effective width of the photoreceptor.
An object of the present invention is to provide a sheet separating device that does not cause image distortion.

Structure of the Invention In order to achieve the above object, the sheet separating device according to the present invention includes a pinch roller that guides the sheet coming out of the separating roller so as to be wound around the separating roller and the conveying roller, and is arranged adjacent to the separating roller, and The diameter of the roller is larger than the diameter of the separation roller and has a maximum diameter at the end farthest from the separation roller.

Embodiments Examples of the present invention will be described below with reference to the drawings. Although FIG. 4 shows an embodiment according to the present invention, various members are omitted for convenience of explanation. That is, as shown in FIGS. 1 and 2, the sheet separating device according to the present invention basically includes a separating roller 7, a deflecting roller 8, and a separating belt 6, and also includes a pinch roller. 9 and a guide pin 10 are additionally provided.

In one embodiment of the invention, the deflection roller 8 is
The diameter increases as the distance from the separation roller 7 increases. That is, the diameter b of the deflecting roller 8 on the separating roller side is equal to the diameter a of the separating roller 7, but the diameter c on the opposite side is larger than the diameter a of the separating roller. FIG. 5 shows a deflection roller 8 having another shape, in which a portion including the end opposite to the separation roller 7 has a diameter c larger than the diameter a of the separation roller 7. Furthermore, if the degree of increase in the diameter of the deflection roller 8 is small, the deflection roller 8 as a whole may be made larger as shown by the imaginary line in FIG.

When separating sheets using such a deflecting roller, even if the sheet 3 is conveyed in a rising state as shown in FIG. Since the portion of the deflection roller 8 also rises with a large curvature, the sheet maintains contact with the deflection roller, so that the sheet 3 as a whole is fed along the guide plate 5 as it is. Furthermore, as can be seen in FIG.
Since the distance between the deflection roller 8 and the photoreceptor 1 is smaller than the distance between the The sheet begins to be separated from the photoreceptor under the force, and as a result, the sheet can be pressed against the guide plate 5 faster than the side edge on the separation belt side. Furthermore, since the diameter of the deflection roller is larger than the diameter of the separation roller, the surface speed of the deflection roller is faster;
The sheet quickly reaches the state shown by the two-dot chain line in FIG. Therefore, it can be seen that the distortion is substantially eliminated after the image is transferred onto the sheet.

Effects of the Invention According to the present invention, the pinch roller that guides the sheet coming out of the separation roller so as to be wound around the separation roller and the conveyance roller is disposed adjacent to the separation roller,
Since the diameter of the deflection roller is larger than the diameter of the separation roller at the end farthest from the separation roller and is only formed at its maximum diameter, it is possible to increase the width of the separation belt or restrict the deflection angle of the sheet to a small value. It is possible to separate the sheets without causing image distortion during transfer, and because the structure is extremely simple, the price of the device does not increase, and the posture of the sheet after transfer can be maintained properly. Since the sheet sag, the running posture of the sheet after transfer is made appropriate, and wrinkles do not occur in a fixing device or the like.

[Brief explanation of the drawing]

Figure 1 is a side view of a conventional sheet separating device, Figure 2 is a side view of a conventional sheet separating device;
3 is a plan view showing the relationship between a separating roller, a deflection roller, and a photoreceptor; FIG. 4 is a perspective view of a sheet separating device according to an embodiment of the present invention; FIG. FIG. 5 is a plan view similar to FIG. 3 showing another deflection roller shape according to the invention. 1...Photoreceptor, 2...Transfer corona discharger, 3...
... Sheet, 6 ... Separation belt, 7 ... Separation roller, 8 ... Deflection roller, 9 ... Pinch roller.

Claims (1)

[Scope of Claims] 1. A separating belt arranged so that the sheet moves along one edge of the photoreceptor over which the sheet is separated downstream of the transfer area, and a side edge of the sheet on the belt. In a sheet separating device comprising a separating roller that rotates to separate the sheet from the photoreceptor in contact with the photoreceptor, and a deflection roller that is coaxially arranged in parallel with the separating roller and regulates the posture of the sheet in a portion other than the separating roller. , a pinch roller that guides the sheet coming out of the separation roller so as to be wound around the separation roller and the conveyance roller is disposed adjacent to the separation roller, and the diameter of the deflection roller is such that the diameter of the deflection roller is larger than that of the separation roller at the end of the side farthest from the separation roller. A sheet separating device characterized in that the sheet separating device is formed to have a maximum diameter larger than the diameter of the sheet separating device.