JPH0247657Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a sheet clamp device for winding and fixing sheets around a drum, and more specifically, for master sheets in offset printing machines, manuscripts and recording paper in facsimile machines, and copying machines in copying machines. This invention relates to a sheet clamping device for paper, etc.

(Prior Art) Various types of seat clamp devices have already been proposed and put into practical use. An electrophotographic copying machine will be described as an example of this device. In FIG. 1, an image of an object 2 placed on a transparent plate 1 is projected via an optical system 3 onto a photoreceptor 4 rotating in the direction of the arrow, and is visualized by a developing section 5. On the other hand, the top sheet of the sheets S loaded in the paper feed cassette 6 is sent by the paper feed roller 7 toward the pair of registration rollers 8. After the paper stops at this point, it moves to the registration roller pair 8.
is sent toward the transfer drum 9 by the rotational feeding action of. The transfer drum 9 is provided with a sheet gripper 11 that can move toward and away from the circumferential surface of the drum.The leading edge of the sheet enters the gripper 11 that is spaced apart from the drum circumferential surface, and then the gripper 11 approaches the drum circumferential surface. The leading edge of the paper is clamped between the paper and the drum. Then, the paper is tightly squeezed and wound around the drum peripheral surface by the squeezing roller 12, and the leading edge of the paper and the leading edge of the visible image forming area on the photoreceptor 4 are connected to the transfer section. It is adapted to meet preferably at 13. Next, the visible image is transferred onto a sheet of paper by a transfer charger 14 fixed to the transfer drum 9, and after this transfer, the residual developer on the photoreceptor 4 is removed by a cleaning device 10.

In addition, in the case of a color copying machine, the photoreceptor 4 has the following:
Since electrostatic latent images are formed by the number of so-called color separations, the transfer drum 9 rotates by the number of color separations.
After completing the last transfer, the gripper 11 moves to the separating claw 1.
6, the gripper 11 separates while the leading edge of the paper is assisted in separation by the charger 15, lifting the leading edge of the paper from the circumferential surface of the drum 9 and separating it.

Next, the leading edge of the paper rests on the separation claw 16, and
After the paper is completely separated from the drum circumferential surface, the paper is discharged to a tray 19 via a fixing device 17 and a pair of paper discharge rollers 18.

Details of the transfer drum 9 are shown in FIGS. 2 and 3. That is, in these figures, the transfer drum 9 has a ring body 21 and a ring body 21.
Mylar (trade name) sheet (not shown) is wound except for the connecting portion 21c. Both rings 21a and 21b of the ring body 21 have circumferential grooves 21.
A groove 21c 1 is provided in a ₁ and 21b ₁ and in a connecting portion 21c _that connects both rings 21a and 21b. Sheet gripper 2 is installed in groove 21c ₁ .
A shaft 23 that fixes the base end of the holding plate 2 and the base end of the holding plate 24 are stored.

Both shaft ends of the shaft 23 of the sheet gripper 22 are rotatably supported by both bearing pieces 25 and 26 screwed into both circumferential grooves 21a ₁ and 21b ₁ . The sheet gripper 22 has a clamp piece 22 at its free end.
a and a flip-up piece 22b, of which the flip-up piece 22b is adapted to fit into a rectangular hole 21c ₂ made in the connecting portion 21c.

The base end of the holding plate 24 made of an elastic plate is connected to the screw 2.
7 to the groove _21c1 , and the free end 24a is self-resilient to the sheet gripper 22.
is holding down. Further, the free end side of the presser plate 24 covers the pivoting portion of the sheet gripper 22, that is, the portions of both bearing pieces 25 and 26.

Here, the sheet gripper 22 is an extension of the pair of registration rollers 8 in FIG. 1, and is timely separated (second position) by the action of the cam 28 so that the leading edge of the sheet enters between the clamp piece 22a and the flip-up piece 22b. do. Next, the gripper 22 approaches and the leading end of the paper is clamped between the clamp piece 22a and the top of the connecting part 21c (first position). That is, the leading edge of the paper is held between the clamp piece 22a and the drum peripheral surface.

In this way, the paper is clamped, but in the case of unclamping, the separation claw 16
In the vicinity of the sheet gripper 2 due to the action of the cam,
2 are separated (second position), and at this time the flip-up piece 22
b pushes up the leading edge of the paper and separates it from the drum circumferential surface.

A cam mechanism for actuating the sheet gripper 22 is shown in FIG. The cam (hereinafter referred to as a gripper cam) 28 is swingable around a support shaft 30, and the outer surface 28a is attached to the seat gripper shaft 23.
The inner surface 28b can come into contact with a cam follower 34 at the end of one arm 31a, which will be described later. Similarly, the grip release cam 29 is swingable around the support shaft 32, and the outer surface 29a can come into contact with the bent tip of the sheet gripper shaft, and the inner surface 29b is attached to the other arm 31b, which will be described later. It can come into contact with the cam follower 35 at the end. The grip cam 28 is disposed substantially in the extending direction of the pair of registration rollers 8, and the grip release cam 29 is disposed near the separating claw 16, and the compressible coil spring 38 gives them a tendency to approach each other (first position). It is being The support shafts 30 and 32 are attached to a support member (not shown) that rotatably supports the transfer drum 9. The arm member 31 has a support shaft 3 which is a pivot point at an intermediate portion between the grip cam 28 and the grip release cam 29.
Cam followers 34 and 35 are respectively implanted at the tips of arms 31a and 31b, which are fixedly attached to arms 31a and 31b and extend in opposite directions. Support shaft 33
is adapted to be swung at an appropriate time by a drive source (not shown), such as a servo motor or a solenoid. That is, when clamping the leading edge of the paper and releasing the leading edge of the paper, the drive source is energized to swing the arm member 31 to the second position, and the cam followers 34 and 35 installed at the ends of the arms 31a and 31b move. inner surfaces 28b and 2 of grip cam 28 and grip release cam 29, respectively;
9b is pushed up to the second position. At this time, straight lines A and B connecting the center of the support shaft 33 of the arm member 31 and the points of contact between the inner surface 28b of the grip cam and the inner surface 29b of the grip release cam and the cam followers 34 and 35 at the tip of the arm are as follows.
Usually, it is not orthogonal to each inner surface 28b, 29b. As shown in the figure, when the biasing force acting on the support shaft 33 disappears, the cams 28 and 29 receive a force that rotates inward due to the compression action of the coil spring 38 and returns to the original first position. Therefore, the drive source requires a large amount of power to counteract this.
Another disadvantage is that harmful vibrations are imparted to the transfer drum via the support.

(Purpose of the invention) The present invention was made to solve the above-mentioned drawbacks of the prior art, and its purpose is to provide a sheet clamping device that consumes less power and prevents vibration of the transfer drum.

(Structure of the invention) The above purpose is to align the inner surface of the cam, whose outer surface is in contact with the shaft end fixed to the seat gripper, with a straight line connecting the tip of the arm that pushes up the cam and the pivot point of the arm. This is achieved by extending it in the same direction.

The illustrated embodiment will be described below.

FIG. 5 only shows members such as the grip cam 40, grip release cam 41, and arm portion 42 as cams that are the features of the present invention, and other members of the seat clamp device of the present invention are shown in FIG. Since it is the same or equivalent to the conventional configuration explained up to FIG. 3, the same explanation will be omitted here. In FIG. 5, the grip cam 40 is swingably supported around a support shaft 30, and the grip release cam 41 is swingably supported around a support shaft 32. Both cams 40, 4
1, an arm member 42 is supported so as to be swingable around a support shaft 33. These spindles 3
0, 32, and 33 are attached to a support member (not shown), and the shapes of the outer surfaces 40a, 41a of both cams 40, 41 are also the same as before.

Now, in the second position, which is the position where the leading edge of the paper is clamped, the inner surface 40b of the grip cam 40 is
is brought into pressure contact with a cam follower 44 implanted at the tip of one arm 42a of the arm member 42. When there is no command to clamp the paper, the arm member 42 swings counterclockwise in the figure, and the cam follower 44 is retracted into the recess 40c (first position). When the paper is in the paper clamp position (second position shown), the inner surface 40b is connected to the support shaft 3.
3 and the contact point 44a with respect to the inner surface 40b of the cam follower 44. Therefore, cam follower 4
Electric power is only consumed when the arm member 4 rides on the inner surface 40b, but when the arm member 42 is positioned in the illustrated position, no bending moment is applied to the arm member 42, so no electric power is required. Therefore, almost no vibration is applied to the transfer drum.
Similarly, when releasing the leading edge of the paper, the inner surface 41b of the grip release cam 41 is brought into pressure contact with the cam follower 45 installed at the tip of the other arm 42b of the arm member 42 (second position). When there is no command to release the paper, the arm member 42 swings counterclockwise in the figure, and the cam follower 45 moves into the recess 41c.
(first position). When the paper is in the open position shown in the figure, the inner surface 41b is connected to the support shaft 3.
3 and the contact point 45a with respect to the inner surface 41b of the cam follower 45. Therefore, as in the grip cam, the cam follower 45 is attached to the inner surface 41.
It only consumes power when it climbs onto the vehicle, but does not require any power when it is in the position shown. Conventionally, as shown in FIG. 4, in order to maintain the seat gripper in the open position, it was necessary to continue supplying power to a means for driving the arm member, such as a solenoid. Therefore, a solenoid that can generate a large force to continue applying electric power was required, but as in the present invention, by moving each cam to a position perpendicular to the arm member, the coil spring 3
There is no need for a large force to continuously resist the elastic force of 8, and a smaller solenoid can be used than in the past. Therefore, as the solenoid becomes smaller, the impact caused by the solenoid when moving the arm member becomes smaller, which in turn reduces the vibration of the transfer drum.

(Effect of the invention) As is clear from the above explanation, the present invention has the inner surface of the cam whose outer surface is brought into contact with the shaft end fixed to the seat gripper, and the tip of the arm that pushes up the cam and the arm. Since it extends in a direction perpendicular to the straight line connecting it to the pivot point, it has excellent effects such as low power consumption and less vibration of the transfer drum.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of an electrophotographic copying machine to which the present invention is applied; FIGS. 2 and 3 are sectional views and perspective views showing a portion of a sheet clamp device;
FIG. 4 is a diagram for explaining the shapes of a conventional grip cam and a grip release cam, and FIG. 5 is a diagram for explaining the shapes of a grip cam and a grip release cam according to the present invention. 22... Seat gripper, 28, 40... Grip cam, 29, 41... Grip release cam, 3
0, 32, 33... Support shaft, 31, 42... Arm member, 31a, 41a... One arm, 31
b, 41b...other arm, 28b, 29b,
40b, 41b...inner surface, 34, 35, 44,
45... Cam follower.

Claims (1)

[Claims for Utility Model Registration] The drum is swingably supported at its base end, and by displacement of a cam provided on the support, the free end is moved to a first position close to the circumferential surface of the drum and the free end thereof is moved. a seat gripper that is selectively located at a second position spaced apart from the drum circumferential surface; and a seat gripper that is pivotally connected to a support that rotatably supports the drum and is selectively located at the first position and the second position. an arm member; a sheet gripper actuating means for causing an inner surface of the cam to press against an end of the arm member; when the arm member is in a first position, the sheet gripper is actuated via the cam; 1 position, and when the arm member is located at the second position, the seat gripper is located at the second position via the cam, and when the arm member is located at the second position, the seat gripper is located at the second position. A seat clamp device characterized in that an inner surface of the cam extends in a direction perpendicular to a straight line connecting a pivot point of the arm member and an end of the arm member.