JPS5981667A - Two-stage transferring device of copying machine or the like - Google Patents

Abstract

PURPOSE:To impress and adjust press-contacting force between each roll and a photosensitive drum independently by providing a pressing means between frames of a transfer and an intermediate transfer roll and an energizing means between the intermediate transfer roll and the photosensitive drum. CONSTITUTION:The frame 13 of the intermediate transfer roll 3 is supported pivotally on a support shaft 15 and the frame 14 of the transfer roll 2 is supported pivotally on a support shaft 16 on a frame 15 respectively; and the press- contacting force between both rolls is adjusted by adjusting screws at upper ends of both frames. The roll 3 is pressed against the photosensitive drum 1 through the frame 13 by the tensile force of a spring 17. Therefore, the press- contacting force between the rolls 3 and 2 exerts no influence upon press- contacting force to the drum 1, so the press-contacting force between each roll and drum is adjusted independently. Further, when an eccentric cam is rotated, the rolls and drum leave each other and the press-contacting force is released in a transfer stop, so the durability of roll surfaces is increased.

Description

[Detailed description of the invention]

The present invention relates to a two-stage transfer type transfer device in an electrophotographic copying machine or the like. Conventionally, in a copying machine or the like, a toner image formed on a toner image carrier is transferred to a recording paper or the like via an intermediate transfer roller in order to prevent damage to the surface of the toner image 41].
There is a so-called two-stage transfer method. 4iR type transfer devices have been proposed as such two-stage transfer type transfer devices, and one of the improved examples thereof may be one having a configuration as shown in FIG. 1. Diagram I4
1 is a photosensitive drum that serves as a toner image bearing member for forming a toner image, and 2 is a transfer roller that transfers the toner image onto a recording sheet. 3 is a photosensitive drum 1 and a transfer roller 2
This is an intermediate transfer roller that is brought into pressure contact with the photoreceptor drum 1 and once transfers and carries the toner image on the photoreceptor drum 1 onto its surface. A bearing member 4 supports the rotating shaft 3a of the intermediate transfer roller 3, and is slidably supported in an oval-shaped support hole 6 provided in the arm 5. The arm 5 is rotatably supported by a pin 9 on a support member (not shown) of the photoreceptor drum. 7.7
is a pin provided on the arm 5, and a spring 8 for biasing the bearing member 4 of the intermediate transfer roller 3 is installed between the pins 7 and 7.
Both ends are stretched. The spring 8 presses the intermediate transfer roller 3 against the photosensitive drum and the transfer roller 2 via the bearing member 4. Note that 0 is a stopper that stops the swinging of the arm 5 at a predetermined position. In the two-stage transfer device having such a configuration, the intermediate transfer roller 3 is inserted into the support hole 6 via the bearing member 4 in the direction indicated by the arrow A.
The photoreceptor drum 1 can be slid in the direction by the spring 8.
On the other hand, arm 5 is supported so as to be swingable in the direction of arrow B, but due to its own weight 1, it rotates clockwise in the figure and is positioned by stopper 10). and photoreceptor drum] and intermediate transfer

[The contact pressure between the intermediate transfer port 3 and the transfer roller 2 is applied by a spring 8, and the contact pressure between the intermediate transfer port 3 and the transfer roller 2 is applied by a pressing member (not shown) to move the transfer IJ-ra 2 in the direction of arrow C. It is applied by biasing the direction. However, even a slight change in the contact pressure between the photoreceptor drum 1 and the intermediate transfer plate 93 affects the image quality.
In addition to stabilizing its size, it is desirable that the pressure applied to the transfer roller and the vibrations of the transfer roller be transmitted. However, in the above configuration, the intermediate transfer roller 3 and the arm 5 that supports it are each rotatable, and the intermediate transfer roller 3 is supported by the arm 5 so as to be slidable in the direction of arrow A. Therefore, the contact pressure of the transfer roller 2 against the intermediate transfer roller 3 influences the contact pressure of the intermediate transfer roller 3 against the photosensitive drum. That is, as shown in FIG. 2, if the pressing force for pressing the intermediate transfer roller 3 against the photosensitive drum 1 is fl, and the pressing force for pressing the transfer roller 2 against the intermediate transfer roller 3 is f2, then fl is set to an appropriate value in advance. Even if the transfer roller 2 is adjusted to f2 and is brought into contact with the intermediate transfer roller 3, the intermediate transfer roller 3 will be pressed in the direction of f2 with a pressing force of f2', and this f2'
The resultant force f3 of and fl presses the photoreceptor drum 1, and the contact pressure against the photoreceptor drum 1 increases. It is possible to set fl in advance by taking into account the influence of the pressing force f2 of the transfer roller, but since the frictional force between the support hole 6 and the bearing member 4 is also involved, it is possible to stabilize the contact pressure against the photoreceptor drum. It is difficult to do so. The present invention was made in order to eliminate the drawbacks of such improved examples of conventional two-stage transfer devices, in which a frame supporting transfer ports is pivotally connected to a frame supporting an intermediate transfer roller, and there is a gap between the two frames. A suppressing means for pressing both rollers is provided, and a biasing means for pressing the intermediate transfer roller against the toner image bearing member is provided on the intermediate transfer roller support frame, and between the toner image bearing member and the intermediate transfer roller. intermediate transfer

[
, 7-A two-stage transfer device of a copying machine in which the pressure contact force between the roller and the transfer roller can be applied and adjusted independently of the IL.
). The present invention will be described in detail below based on Examples. FIG. 3 is a plan view of an embodiment of a two-stage transfer device such as a copying machine according to the present invention. Figure 3 (here, ]], ]2
are bearing members for the intermediate transfer roller 3 and the transfer U-roller 2, respectively, and are fixedly supported by the frames 13 and 14, respectively. The frame 13 is a support shaft attached to a supporting portion (not shown) of the photoreceptor drum 1 which is an image carrier] 5
The frame 4 is rotatably supported relative to the frame 3 by a support shaft 6 fixed to the frame 13. Further, bent portions 13 a and 14 a are provided at the upper end portions of the frames 13 and 14, respectively, so as to be spaced apart from each other and face each other. and bent part J3a
A screw hole is formed in the bent portion 14a, and an insertion hole is formed in the bent portion 14a. Reference numeral 18 denotes a contact pressure adjusting screw screwed into the screw hole of the bent part 13a through the insertion hole of the bent part 14a, and 19 denotes a compression spring inserted between the head of the screw 8 and the bent part 14a. By adjusting the screwing amount of the screw j8, the frame 14 is rotated with respect to the frame 13, and the contact pressure of the transfer roller 2 against the intermediate transfer roller 3 is adjusted. J7 is a spring stretched over the lower end 13b of the frame 3, which rotates the frame 3 counterclockwise about the spindle 15, thereby pressing the intermediate transfer roller 3 against the photosensitive drum. . Reference numeral 20 denotes an eccentric cam, and by rotating it by a predetermined angle, the lower ends 14b, 13b of the arms 14, 13 are
are sequentially pressed to rotate the frames 14 and 13 against the springs 19 and 17, and move the transfer roller 2 and the intermediate transfer roller 3 away from the intermediate transfer roller 3 and the photosensitive drum 1, respectively. It is something. Note that frame 13.
The lower end portions 13b, 14b of 14 are formed so as to be shifted relative to the eccentric cam 20 so as to sequentially contact the eccentric cam 20. In the two-stage transfer device configured as described above, in order to bring the photoreceptor drum J into pressure contact with the intermediate transfer roller 3, and between the intermediate transfer roller 3 and the transfer roller 2 in order to perform a transfer operation, first, the eccentric knob 20 is rotated. Then, the pressure on each frame by the cam 20 is released. By releasing this pressure, the bearing 71 (frame supporting i'1) of the intermediate transfer roller 3 rotates counterclockwise around the spindle]5 due to the tensile force of the tension spring]7. Therefore, the intermediate transfer roller 3 is driven once in the direction indicated by the arrow and comes into pressure contact with the photosensitive drum j). ↓ 5. In this case, the frame 13 is a pair of front and rear frames to form a complete frame 4H, and only both ends of the support shaft 15 and the bearing portion 11 of the intermediate transfer roller are attached to this pair of frames. This frame growing body has a degree of freedom against twisting, so even if the parallelism between the photoreceptor drum and the support shaft 5 is slightly off, the photoreceptor drum and the intermediate transfer roller 3 will be able to maintain their full width. It is possible to deform appropriately so that uniform contact is made over the entire area. On the other hand, the transfer roller 2 rotates with respect to the frame 13 around the fulcrum J6 together with the frame 14! \IJ i11 The contact pressure adjusting screw]8 is arranged in the position 11 and is configured to be able to approach and separate from the intermediate transfer roller 3. When the bent portion 14a is tightened against the spring 9, the bent portion 14a is pressed in the direction of the arrow E. Therefore, the frame 4 is rotated in the direction of the arrow F about the support shaft 16, and as a result, the transfer roller 2 is pressed in the direction of arrow G to bring it into pressure contact with the intermediate transfer roller 3. When a transfer operation is performed in this state, the toner image formed on the photosensitive drum J is transferred via the intermediate transfer roller 3 to the recording sheet carried between the respective rollers. Therefore, the contact pressing force of the transfer roller 2 against the intermediate transfer +1- roller 3 based on the rotation of the frame 14 by adjustment of the adjustment screw 18 is applied to the frame 14 supporting the transfer roller 2.
is supported by the frame 13 that supports the intermediate transfer roller 3, so the intermediate transfer roller 3 and the photosensitive drum]
It has no effect on the contact pressure. Further, the tension spring 17 is connected to the frame 1 supporting the intermediate transfer roller 3.
3 is rotated together with the frame 14 and the transfer roller 2 about the support shaft 15, and the intermediate transfer roller 3 is brought into pressure contact with the photosensitive drum 1. Since there is no element C that applies pressing force, the spring 7 has no effect on the contact pressure between the transfer roller 2 and the intermediate transfer roller 3 set by the screw 18 and the spring 17, that is, the transfer pressure. In addition, in a two-stage transfer device having such a configuration, the spring]
7 and ] 9, it is preferable to constantly apply tactile pressure between the photoreceptor tram and the intermediate transfer roller, and between the intermediate transfer roller and the transfer roller, to preserve the surface of those surfaces. Therefore, in the present invention, C rotates the eccentric cup 20 provided close to the lower end portions 131) and 14b of each frame to separate the domes or rollers from each other except during the copying operation. It is something to keep. That is, eccentric cam 2
0 is rotated, the cam surface first contacts the lower end 14b of the frame 14, and the frame ]4 is rotated in the opposite direction to the arrow F against the spring 19, and the transfer roller 2 is moved for intermediate transfer "]- Then, as the rotation of the cam 20 progresses 21-, the cam surface also comes into contact with the lower end 13b of the frame 13, causing the frame 13 to rotate clockwise against the spring 7. It is also possible to separate the roller 3 and the photosensitive drum 1. As explained in detail based on the embodiments above, the present invention has a first frame that supports the intermediate transfer roller and a frame that supports the transfer roller. a second frame rotatably supported by the first frame; a pressure means disposed between the two frames for pressing the transfer roller against the intermediate transfer roller; and a photosensitive member with the intermediate transfer roller as a toner image carrier. Since a two-stage transfer device in a copying machine or the like is constituted by the rotation biasing means of the first frame for bringing it into pressure contact with the body drum, each part between the toner image bearing member and the intermediate transfer roller and between the intermediate transfer roller and the transfer roller is It is possible to adjust the contact pressure independently without affecting each other, so it is possible to obtain good image quality under stable transfer conditions.
can be obtained. In addition, by providing a roller separating means for sequentially rotating the first frame and the second frame, even if pressure means for each roller is provided, when the transfer operation is stopped, the space between the transfer roller and the intermediate transfer roller and the intermediate transfer roller can be increased. The toner image bearing member can be separated from the toner image bearing member, and the durability of the surface of the toner image bearing member and each roller can be increased.

[Brief explanation of drawings]

Figure 1 is a plan view of an improved example of a conventional two-stage transfer device;
The figure is an explanatory diagram illustrating each pressing force in the device shown in FIG. 1, and FIG. 3 is a plan view of an embodiment of a two-stage transfer device such as a copying machine according to the present invention. . In the figure, J is a photosensitive drum, 2 is a transfer roller, 3 is an intermediate transfer roller, 4 is a bearing part, 5 is an arm, 6 is an oval support hole, II, 12 is a bearing member, 13.14 is a frame, 15.16 is the support shaft, 17 is the tension bar, ), 18
19 indicates a contact pressure adjustment screw, 19 indicates a compression spring, and 20 indicates an eccentric cam.

Claims (1)

[Scope of Claims] (J) In a two-stage transfer device such as a copying machine that transfers a toner image formed on a toner image carrier onto a recording sheet via an intermediate transfer roller, the number of times the intermediate transfer roller is supported is I'
a first frame capable of OT, and a first frame supporting a transfer roller;
a second frame rotatably supported by the frame; a pressure means disposed between the two frames for pressing the transfer roller against the intermediate transfer roller; and a pressure means for pressing the intermediate transfer roller against the toner image carrier. 1. A two-stage transfer device for a copying machine, comprising: first frame rotation urging means. (2) In a two-stage transfer device such as a copying machine that transfers a toner image formed on a toner image carrier to a recording sheet via an intermediate transfer roller, a rotatable first frame that supports the intermediate transfer roller; , a second frame that supports a transfer roller and is rotatably supported by the first frame; a pressure means disposed between the two frames for pressing the transfer roller against the intermediate transfer roller; and an intermediate transfer roller. a rotating biasing means for the first frame to press the toner image carrier against the toner image bearing member; and a means for sequentially rotating the first frame and the second frame when the transfer operation is stopped to provide pressure between the transfer roller and the intermediate transfer roller and between the intermediate transfer roller and the intermediate transfer roller. A two-stage transfer device such as a copying machine, comprising: and a roller separating means for separating a toner image carrier.