JPS6356541B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer device applied to a transfer type electronic copying machine, and particularly to a transfer device suitable for use in a color copying machine.

In conventional color copying machines, in order to superimpose a powder image formed on a photoreceptor onto transfer paper, the transfer paper is wound around a transfer roller and transfer is performed three or four times. This method is based on the so-called roller transfer method, and when performing multiple transfers,
In the area where there was a toner image before, during the next transfer,
The next toner becomes difficult to apply. So-called hollow development occurs. Furthermore, when the transfer paper is charged and attracted to the roller, due to changes in the resistance of the transfer paper, it becomes difficult to wrap around the transfer roller when the humidity is high, and transfer failures tend to occur when the humidity is low. Therefore, the roller transfer method has many disadvantages in obtaining a final image of good quality with good color balance.

There are also problems in the configuration and use of the device. For example, in a copying machine that uses transfer paper of different paper sizes, if a small size transfer paper is used, the toner on the image drum will adhere to the area of the transfer roller where there is no paper, and then When using large-sized transfer paper, this area may cause stains on the back side or cause non-uniformity of the transfer electric field, causing uneven transfer. Therefore, cleaning means for the transfer roller is indispensable, and the operation of this cleaning means must be performed when there is no transfer paper, which is extremely troublesome.

On the other hand, instead of using a transfer roller, it is conceivable to carry out the transfer by gripping the leading edge of the transfer paper with a gripper and transporting the transfer paper to the transfer position. According to this method, compared to the case where the transfer roller is used, the transfer paper can be reliably conveyed to the transfer position even when transfer is performed a plurality of times. However, if this gripper is grounded, the transfer paper absorbs moisture and the resistance of the transfer paper decreases, especially in a humid usage environment, and the transfer charge flows into the gripper, causing the transfer near the gripper. There was a problem when a defect occurred.

An object of the present invention is to provide a transfer device that always performs good transfer when performing multiple transfers onto a transfer material.

That is, the present invention provides a transfer device that transfers a phenomenon image formed on an image carrier onto a transfer material, which includes a corona discharge means provided at a transfer position facing the image carrier, and a corona discharge means that conveys the transfer material to the transfer position. In order to do this, the present invention is characterized in that it has a gripping means that grips and moves the leading end of the transfer material, and that this gripping means is electrically insulated. As a result, even if the resistance of the transfer material decreases and the conductivity increases in high humidity, the present invention can prevent the transfer charge to be applied to the transfer material from flowing into the gripping means and being reduced. can. Therefore, a good transferred image without transfer defects can be obtained even in high humidity.

The details of the present invention will be explained below using specific examples with reference to the drawings. FIG. 1 shows a side view of an embodiment of an electrophotographic machine using a transfer device according to the present invention. To explain its operation, the original on the platen glass 1 is integrated with the first scanning mirror 4. The light is irradiated by the configured illumination system (yaws lamp 3 and reflective shade 2), and the reflected light is scanned by the first scanning mirror 4 and the second scanning mirror 5. The first and second scanning mirrors move at a speed ratio of 2:1 to
The original scanning is performed while keeping the optical length of the first half constant. The above reflected light image passes through the lens 6 and reaches the color separation filter 7, which separates the light image into three colors [red (R), green (G),
Blue (B)] is color-separated by any one of the filters 7a, 7b, and 7c, and the color-separated light image is sent to a fixed third mirror 8 and a fourth mirror 9, and then to a dust-proof sealed glass 10. through the photosensitive drum 11
image on top. The photosensitive drum 11 is rotatably supported on a shaft 11a, rotates in the direction of the arrow with printing operations, is charged (for example, +) by a primary charger 12, and is then irradiated with the color-separated optical image. , static electricity is removed using AC or a static eliminator 13 with a polarity opposite to that of the primary, and then the entire surface is exposed and a lamp 14 is used to remove the static electricity.
Uniformly irradiates the entire surface to obtain a high-contrast electrostatic latent image.

The electrostatic latent image on the photosensitive drum 11 is then transferred to a developing device 15.
visualized by The developing units 15 are 15a for cyan (C), magenta (M), yellow (Y), and black.
It is composed of four developing devices 15b, 15c, and 15d, and the developing device corresponding to the color separation filter (for example, the yellow developing device 15c for the blue filter 7c) performs development.

The transfer paper 16 in the cassette is fed into the machine by the paper feed roller 17, and the first timing is taken by the timing roll 18a.
At step 8b, it is fed into the opening of the gripper 19 with even more accurate timing. Then, the opening of the gripper 19 closes at the position where it is removed from the cam 20, and the leading edge of the transfer paper is gripped by the gripper 19.

Next, the transfer corona charger 21 and the photosensitive drum 1
While the transfer paper 16 passes between the photosensitive drums 1 and 1, the developed image on the photosensitive drum is transferred onto the transfer paper. For color copying, use the gripper 1 while holding the transfer material 16.
9 rotates three times, and after the three-color transfer, the separating claws 22 and the gripper opening cam 23 operate to release the transfer material from the gripper and transfer it to the conveyor belt 24. After being transferred, the transfer paper is heat-fixed by a heat-fixing device 25 and then discharged.

In this device, the transfer mechanism has various features to enable good transfer. Figure 2 shows a side view of the transfer mechanism;
The figure is a perspective view thereof.

First, the conveyance guide 26 provided between the timing roller 18b and the transfer conveyance gripper has a movable structure. This conveyance guide has a fixed upper guide plate 26a and a lower lower guide plate 26b.
is rotatably provided around the shaft 27a, and when the solenoid SOL-1 is turned off, the lower guide plate 26
b falls downward due to its own weight. Specifically, the transfer paper 16 is fed in at a certain timing by the timing roller 18b, and is fed into the gripper 19 through the guide portion. At this time, the transfer paper 16 is fed at a speed faster than the moving speed of the gripper, so for example, if the transfer paper is 40% faster than the gripper, if the gripper is left open for a length of about 12 mm, the transfer paper will move about 5 m/min. It is grasped by entering the inside of the body by about 100 m. At this time, the solenoid SOL-1 is turned off and the lower guide 26b rotates by its own weight to the position shown by the chain line, so that the lower guide no longer applies resistance to the transfer paper. Moreover, since the lower guide is opened, the transfer paper is not held within the narrow guide 26, so that wrinkles do not occur in the transfer paper.

Further, in the first illustrated example, a guide 27 and a tray 28 are provided adjacent to the transfer paper gripping position of the gripper. Paper detection means, such as a lamp 29 and a light receiving element 30, are provided on the tray or on its path to detect the intrusion of transfer paper. To explain the operation of this constituent mechanism, the transfer paper sent by the second timing roller 18b is moved to the gripper 19 by the cam 20.
The arm 19a rides on the gripper 19 and normally enters into the open gripper 19. However, the timing of the gripper 19 and the transferred paper did not match, and the gripper stand 19b and the gripper presser 19
Since the timing roller 18b continues to rotate even when the transfer paper is not sandwiched between the timings c and 18c, the transfer paper continues to be fed. At this time, a guide 27 is disposed facing downward with respect to the leading edge of the transfer paper, and due to the synergistic effect of this guide 27 and the descent of the transfer paper due to its own weight, the leading edge of the transfer paper is sent downward by the guide 27 to the tray 28. will be stored in. If the storage of the transfer paper is detected by a detection means, and based on the detection signal, the operation of the jam detection control circuit, which normally detects paper feeding failure and stops the device, is controlled so as not to stop the device, it is possible to prevent the gripper from stopping. To enable a subsequent paper feeding operation without stopping the apparatus in the event of paper feeding failure. Therefore, loss of copying time due to paper feeding failure is significantly reduced. Moreover, since the transfer paper that has failed in feeding does not reach the photoreceptor, accidents such as the transfer paper damaging the photoreceptor surface can be avoided.

Furthermore, the configuration of the gripper section of this transfer device will be explained. The gripper part 19 that grips the transfer paper needs to pass between the photoreceptor 11 and the transfer corona charger 21, and in order to pass through this gap, the overall thickness is usually required to be thin (for example, about 8 mm). Ru. The configuration of the gripper under these conditions is
Although it requires the following conditions, it also poses difficulties.

That is, each gripper requires sufficient pressing force to grip the transfer paper. In particular, it is necessary to prevent paper slippage even during multiple transfers. However, if the base member of the gripper part is made thin, there is a risk that deformation will occur when the grip is released.

In particular, if the base member of the gripper is thin and each gripper is independently pressed against the base member with a strong pressing force, the timing may not match when pushing each gripper up to release the gripper.
The platform itself may deform and follow the movement of the grippers, making it impossible to obtain sufficient release clearance.

In the example shown in FIG. 3, individual gripper pieces 19c are provided on a common shaft 19d, and the transfer paper is gripped and released by the gripper pieces at the same time by rotating and pressing the shaft. With this configuration, the gripper can be opened without fear of deforming the base member.

On the other hand, in this configuration, the pressing force of each gripper may be uneven. In this embodiment, an elastic movable structure using a spring or the like is provided on the table on which the gripper comes into contact, in order to equalize the pressing force. Specifically, as shown in the cross section shown in FIG. 4, a gripper piece 19c is fixedly provided on a rotatable common shaft 19d, while a movable piece 19e is elastically movable on a base 19b by a spring 19f. 19b. When the gripper pieces are closed, the transfer paper can always be gripped with an appropriate force due to the gripping force determined by the elastic force of the spring 19f relative to the holding force of the gripper.

When the gripper is released, the movable piece 19e pops out onto the stand 19b, so that the transfer paper is lifted off the gripper stand and can be easily separated by the separating claws 22. Therefore, by lifting the transfer paper, it becomes easier to eject the paper from the gripping means.

As a modification to facilitate separation of the transfer paper after this transfer step, the configuration shown in FIG. 5 may also be used. This is a push-up member 3 having approximately the same structure as the gripper piece 31.
2 is provided on a gripper stand 33, and at the position where the transfer paper is gripped, only the gripper piece is released, but the push-up member 32 remains in close contact with the stand. At this time, it is preferable to provide a notch in the surface of the table 33 to prevent the push-up member 32 from protruding. Therefore, the leading edge of the transfer paper is inserted onto the table in such a manner that it also covers the push-up member, and is gripped by the grip. In the illustrated example, each gripper piece 31 for gripping has a cam 34.
The protrusion 34a is released by pushing up the cam 31. Therefore, in the gripping position, only the gripper piece has the cam protrusion 34a in the operating position, and one of the pushing member parts does not have the cam protrusion 34a.

In the separation release position, the cam protrusion 35a of not only the gripper piece but also the push-up member 32 is placed in the operating position, and the push-up member pushes up the edge of the transfer paper as the gripper is released. At this time, it is preferable that the amount of protrusion of the cam relative to the push-up member is smaller than the amount of protrusion of the gripper piece. Alternatively, the length of the height portion 32a of the push-up member 32 may be changed while the amount of cam protrusion is the same.

With the above configuration, the leading edge of the transfer paper can be lifted well,
The separation claw is easily inserted under the leading edge of the transfer paper, allowing quick separation (FIG. 6).

The above-mentioned gripping mechanism enables extremely good gripping.

The above-mentioned gripping mechanism is attached to a chain suspended between a pair of rollers and rotated (Fig. 1),
Alternatively, it is used by being mounted on a rotatably supported drum (Fig. 7).

In the example shown in FIG. 2, a rotating suction hole 38 provided coaxially with the separating claw 22 further adds a conveying force to the transfer paper. In the illustrated example, while the pipe having the suction hole is rotated, the separating claws 22 are provided coaxially through a bearing material, so that they can be operated independently. After the separation claw 22 transfers a predetermined color image onto the transfer paper as described above, the plunger SOL-2 operates for separation and reaches the solid line position. After the separation operation, the plunger SOL-2 is turned off and returned to the position shown by the broken line by the elastic force of the spring 39.

According to the present invention, the gripper is electrically insulated from ground in order to improve the transfer efficiency in high humidity conditions. This prevents the charge applied to the transfer paper by the transfer corona from flowing into the main body of the apparatus through the gripper and reducing the transfer electric field.

In a drum-shaped transfer device equipped with a gripper, it is conceivable to electrically insulate and support the gripper by using a resin material in the bearing portion of the rotating shaft.

On the other hand, as described above, neutralizing the electric charge added to the transfer paper by the transfer corona discharger 21 using the static eliminator 37, when performing the transfer process multiple times,
It is good to operate it in the final transfer step.
For example, if it is activated before the final transfer step, there is a possibility that the toner will fall off the transfer paper or be offset to the roller 36. This static elimination also eliminates static electricity from the gripper, so that adsorption of the transfer paper to the gripper hardly occurs. Furthermore, it is good to apply a voltage to the gripper part to assist the transfer, and this is particularly effective in humid conditions because the conductivity of the transfer paper is high.

As explained above, according to the present invention, by electrically insulating the gripper, which is the gripping means,
Particularly good transfer can be performed even in high humidity.

[Brief explanation of the drawing]

FIG. 1 is a side view of a specific example of a copying machine to which a device according to the present invention is applied, FIG. 2 is a side view of a specific example of a transfer device of the present invention, FIG. 3 is a perspective view of the device shown in FIG. 2, and FIG. 5 and 6 are perspective views showing the opening/closing mechanism of the gripper, and FIG. 7 is a side view of a different embodiment of the transfer device of the present invention. In the figure, 16 is a transfer material, 19c, 31, 1
2 indicates a gripper piece.

Claims (1)

[Scope of Claims] 1. A transfer device that transfers a developed image formed on an image carrier to a transfer material, comprising: a corona discharge means provided at a transfer position opposite to the image carrier; A transfer device comprising: a gripping means that grips and moves a leading end of a transfer material in order to transport the transfer material to a transfer material, and the gripping means is electrically insulated.