JPS6149662B2 - - 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.

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. Another object of the present invention is to provide a transfer device that enables efficient transfer operations.

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. It is irradiated with the constructed 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 (7a, 7b, 7) corresponding to the three colors [red (R), green (G), blue (B)].
The colors are separated by one of the filters c, and the color-separated optical image passes through the fixed third mirror 8 and fourth mirror 9, and further passes through the dustproof sealing glass 10, and forms an image on the photosensitive drum 11. The photosensitive drum 11 is a shaft 11
It rotates in the direction of the arrow with the printing operation, is charged (for example, +) by the primary charger 12, and then is irradiated with the color-separated light image while being charged with AC or primary charger. Static electricity is removed using a static eliminator 13 of opposite polarity, and then the entire surface is exposed to light and uniformly irradiated with a lamp 14 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 for cyan (C), magenta (M), yellow (Y) and black.
It is composed of four developing devices a, 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. FIG. 2 shows a side view of a transfer material conveyance mechanism that has a gripper and moves the transfer material endlessly.
FIG. 3 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 section. 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 penetrates into the interior and is grasped. 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 transfer paper is not held in the pinch guide 26 by opening the lower guide, wrinkles do not occur in the transfer paper. Because the above configuration does not cause wrinkles on the transfer paper,
This eliminates the possibility of inconveniences such as omissions in the transferred image during transfer or problems with subsequent conveyance. In particular, it is extremely effective to increase the transport speed of the transfer paper and use the normal speed only during transfer, and the above configuration allows this to be carried out satisfactorily without causing any wrinkles 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 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 arranged 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 away from the gripper by the guide 27. and stored in the tray 28. 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. Furthermore, 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. This configuration allows the gripper to be released without fear of deforming the platform 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.

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. 5).

In the example shown in FIG. 2, a rotating suction hole 31 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 32.

[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. FIG. 5 is a cross-sectional view of the gripper portion and a side view of a transfer device according to a different embodiment of the present invention. In the figure, reference numeral 16 indicates transfer paper, 28 indicates a tray for storing transfer paper that has failed to be supplied, 29 indicates a lamp of a transfer paper detection mechanism, and 30 indicates a light receiving element for this lamp.

Claims (1)

[Scope of Claims] 1. A transfer device that repeatedly transfers a developed image on an image carrier onto a transfer material, which has a gripper means that grips the leading edge of the transfer material and guides the transfer material to a transfer position, and is capable of endless movement. a transfer material supply means for supplying a leading end of the transfer material to a gripper means of the transfer material transport means; and a transfer material supply means for guiding the transfer material that cannot be gripped by the gripper means in a direction away from the transport means. and a detection means for detecting that the gripper means has failed to grip the supplied transfer material, when the detection means detects that the gripper means is not gripping the supplied transfer material. , a transfer device characterized in that the next transfer material is supplied to gripper means.