JPS6355580A - Transfer device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a transfer device, and more particularly to a transfer device that can be applied to a device having a function of performing overlapping transfer, such as color electrophotography.

(Prior Art) Conventionally, in a color electrophotographic recording device, after a transfer paper is wrapped around a transfer drum made of polyester film or the like, a transfer corona charger sequentially transfers each color toner image on a photoconductor from the back of the film to the transfer drum. It is known that a color image is obtained by transferring the image three or four times to the upper transfer paper.

However, in the conventional apparatus described above, as the number of transfers increases, it becomes difficult to perform sufficient transfer. The reasons for this may be as follows. That is, when the transfer paper is peeled off from the photoreceptor immediately after transfer, a peel discharge occurs, and the transfer paper is charged due to this peel discharge.Since the film on the transfer drum is an insulator, this charge The charge cannot escape and is retained. It is thought that if the next transfer is performed in this state, the electric field will be canceled by the next transfer charger due to the electrical charge, or the transfer charger will be less likely to occur.

Therefore, in order to solve the above-mentioned transfer problem, a method is known in which the transfer current is increased sequentially, but even with this method, the efficiency of the discharge current for the part of the discharge current of the power supply that flows toward the photoreceptor side deteriorates. (Film Den.

Therefore, there is a problem in that a fairly large power source is required to compensate for the inefficiency.

There is also a method of lowering the transfer drum potential by installing a separate charge-eliminating corona charger on the transfer drum and removing the charge after each transfer, but with this method, the toner transferred onto the transfer paper is also removed. , there is a problem that reverse transfer occurs in the next transfer.

(Objective) It is an object of the present invention to provide a transfer device that solves the problems of the prior art described above and can produce stable transferred images even during overlapping transfer with a simple configuration.

(Structure) In order to achieve the above object, the present invention provides a transfer charger on the back side of the transfer material in a transfer gW that performs overlapping transfer by bringing a transfer material into close contact with a dielectric film, and transfers data to the casing of the transfer charger. The device is characterized in that it is configured to apply a voltage that increases successively each time.

Hereinafter, the present invention will be specifically explained based on examples.

FIG. 1 is a schematic diagram for explaining the first embodiment of the present invention,
FIG. 2 is an enlarged explanatory diagram of essential parts of the same embodiment, FIG. 3 is a control block diagram of the same embodiment, and FIG. 4 is a flowchart of the same embodiment.

In FIG. 1, a laser writing system 2 is arranged in a transfer device 1 as is well known, and around a photoreceptor drum 3 are colored C (cyan), 9M (magenta), and Y (yellow).
, Bk (black) developing units 4a, 4b, 4c, 4d.
, a transfer drum 5, a pre-cleaning static eliminator 6, a cleaning device 7, and a static eliminator/charger 8 are arranged.

On the paper feeding side of the transfer drum 5, a folding section 11 consisting of a paper feeding cassette 9 and a paper feeding roller 10 is provided, and on the paper discharging side, a separation claw 1 connected to the transfer drum 5 is provided.
2. Fixing roller pair 13. A fixing/paper ejecting section 15 consisting of a pair of paper ejecting rollers 14 is provided.

The transfer drum 5 is made of aluminum and synthetic resin, and its periphery is covered with a polyester film (not shown) that is a dielectric film. A transfer charger 18 consisting of a casing 16 and a central mold i17 is disposed at a contact portion with the body drum 3, and a static elimination charger 19 is disposed downstream of the transfer charger 18. A high voltage power source 20 is connected to the center electrode 17 of the transfer charger 18 as is well known, and the transfer charger 1
A DC variable bias 21 is connected to the casing 16 of No. 8. Roughly upstream of the transfer charger 18, a potential probe 22 is provided for detecting the film potential of the polyester film after transfer and controlling the DC variable bias 21.

By providing the DC variable bias 21 and the potential probe 22, for example, the DC variable bias 21 can adjust the potential of the casing 16 to a value close to the film potential measured after transfer.
Therefore, the electrodes surrounding the transfer charger 18 have almost the same potential on the casing 16 and the photosensitive drum 3 side (actually, the photosensitive drum 3 also has a potential, so a difference occurs), and the distribution ratio is The corona current becomes constant and the efficiency of the corona current toward the photoreceptor drum 3 side is good.

Furthermore, if a bias higher than the film potential is applied to the casing 1, the efficiency will be further improved.

By doing this, the electric field is canceled out in the next transfer charge due to the electrical charge on the polyester film on the transfer drum that occurs in the conventional device.
This solves the problem that transfer charges are difficult to occur.

Next, the above-mentioned bias effect will be explained using the control block shown in FIG. In the figure, the potential prog 22
detects the potential of the transfer drum 5 after transfer, and after amplifying it to a control level by the potential measurement circuit 23, the A/D
The converter 24 converts the data into digital data and stores it in the ROM25. R
It enters a CPU (central processing unit) 27 having an element such as AM26. The CPU 27 performs comparison calculations according to a predetermined control method, and sends the signal of this calculation result to the D/A.
The converter 28 converts the signal into analog and supplies it to the bias control circuit 29, and depending on the signal, the DC variable bias 2
The bias value of 1 is controlled.

The operation leading to bias control will be explained with reference to the flowchart shown in FIG. When the print start switch is turned on (4-1), the transfer drum 5 starts to rotate (4-2), and then the static elimination charger 19 performs pre-static discharge on the transfer drum 5 (4-3), and the photosensitive drum 3 is initialized (
The drum potential is approximately Ov) and the paper is then fed to the transfer drum 5 (4-4) and wrapped onto the transfer drum 5.

Next, the first transfer is performed (in the figure, n is the number of transfer cycles) (4-5), and then the transfer drum potential is measured by the potential probe 22 (4-6), and according to that value, the transfer drum potential is measured. As described above, the bias of the casing 16 is controlled (4-7), and the second transfer is performed at that bias value (4-8), and the potential measurement, bias control, and transfer are repeated to obtain a predetermined value. When the number of transfers is completed (4-9), the charger 19 removes the electricity from the paper and the transfer drum 5 again (4-10), and then the separation claw 12 separates the barper from the transfer drum 5.
(4-11), and reaches the fixing/wandering paper section 15.

Incidentally, in the embodiment described above, the potential of the transfer drum 5 is measured and the bias value is controlled based on the measured value. Even with a configuration in which the bias of the casing 16 is not controlled at all, the effect is greater.

Further, in the above embodiment, a configuration using one photoreceptor drum 3 and one transfer drum 5 was shown, but as shown in FIG. may be used. In the same figure,
Images are transferred by three photoreceptor drums 3a, 3b, 3c, and each photoreceptor drum 3a, 3b, 3
Around C, there are an illumination lamp 3.0 for the original, a slit 30a, a charger 31, a cleaning section 32, and a static eliminator 3.
3. Developing device 34 for each color of yellow, magenta, and cyan
are arranged, and each photoreceptor drum 3a.

A belt-shaped transfer body 35 is in contact with the lower portions of 3b and 3c, and a transfer charger 36 is disposed in the contact portion.The specific structure of each transfer charger 36 is described in the above-mentioned section. As in the first embodiment, the casing of the transfer charger 36 is biased.

Furthermore, the present invention can also be applied to the copying apparatus shown in FIG. In the same figure, an image scanner 40 for reading a document and a writing section 41 consisting of a laser optical system are used to write 4 images.
The photoreceptor drums 3a, 3b, 3C, and 3a are exposed as appropriate, and similarly to the second embodiment shown in FIG. ,yellow.

A developing device 42, a cleaning section 43, and a charging section 44 are arranged for each color of magenta, cyan, and black, and a belt-shaped transfer body 45 is brought into contact with the lower part of each photoreceptor drum 3a, 3b, 3c, and 3d. This is a known method in which a transfer charger 46 is arranged at the contact portion, and the specific structure of each transfer charger 46 is similar to the first embodiment described above, so that a bias is applied to the casing of the transfer charger 46. .

(Effects) As described above, the present invention can provide a copying device that performs transfer with good discharge efficiency by controlling the bias on the casing of the transfer charger, and that can obtain stable transferred images even during overlapping transfer.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a schematic diagram, FIG. 2 is an enlarged explanatory diagram of main parts, FIG. 3 is a control block diagram, and FIG. 4 is a flowchart. FIG. 5 is a schematic diagram showing the second embodiment, and FIG. 6 is a schematic diagram showing the third embodiment. 16...Casing, 18.36.46...Transfer charger, 21...DC variable bias. 7v1 Figure 2 Figure 3 Figure 5 Figure 4 Figure 6

Claims (1)

[Claims] In a transfer device that performs overlapping transfer by bringing a transfer material into close contact with a dielectric film, a transfer charger is provided on the back side of the transfer material, and the casing of the transfer charger is configured to apply a voltage that increases sequentially for each number of transfers. A transcription device featuring: