JPS6029947B2 - Transfer method for multicolor electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer method for multicolor electrophotography, and particularly to a transfer method applied to multicolor electrophotography using photoreceptors corresponding to the respective colors through separate filters.

Conventional multicolor electrophotography uses a single photoreceptor and repeatedly exposes it to light through three or four types of filters, such as full, green, and red, to form a static latent image. A color image is obtained by developing with colored toners such as yellow, magenta, and cyan, and then transferring each toner the same number of times, or by transferring the latent image to a transfer paper fixed on a drum in advance. A copy image is obtained by transferring the image as is and developing it repeatedly with toners of different colors.

However, these multicolor electrophotographic methods require exposure, charging, development, transfer, etc. to be repeated as many times as there are filters (i.e., types of colored toner), making it difficult to increase the copying speed. .

The present invention solves the above-mentioned drawbacks by using multicolor electrophotography with a long copying speed, that is, by using several types of filters and having the same number of photoreceptors, the toner images of the respective colors are not displaced from each photoreceptor. This is a transfer method used in multicolor electrophotography to obtain color images. The present invention will be explained in detail below based on the illustrated embodiments.

In FIG. 1, transfer papers 1 are aligned and stacked in a paper feed section, and are fed out one by one by a paper feed roller 2.

The sent transfer paper is transferred to a number of drums according to the number of color separations,
In the figure, the image is transferred by three photosensitive drums 3a, 3b, and 3c. The same structural elements are attached to the first drum 3a, the second drum 3b, and the third drum 3c in order to process each process from exposure to transfer. To simplify the explanation, we will now explain the first drum 3a. In the figures, the same symbols represent the same elements, a for those belonging to the first drum, b for those for the second drum, and b for the third drum. Those to which it belongs shall be identified by adding the symbol c. A lamp 6a for illuminating the original 5 placed on the contact glass 4, for example a halogen lamp, passes through a slit 8a made in the upper plate 7 guiding the contact glass 4 and illuminates the original 5. It is arranged at a position suitable for exposing the drum 3a.

The light reflected on the original image 5 is passed through a lens 9a to a blue filter 10a (1ob is a green filter, 10
c is guided to the exposure position 11a of the drum 3a through a liquid filter).

In this case, it is also possible to use a mirror or the like (not shown) to create an optical system with a longer optical path length. The drum 3a is charged by the charger 12a while rotating, and the drum 3a is charged at the exposure position 11a.
is exposed to light to form a static latent image.

This electrostatic port image is produced using yellow toner (1
3b is developed with magenta toner, 13 is developed with cyan toner), and rollers 14, 15, 16, 17, 18 are developed.
Transfer position 20a in contact with belt 19 stretched between
In step 1, a toboot image is transferred onto transfer paper 1. After the transfer has been completed, the drum 3a is neutralized by a quenching lamp such as a crab lamp or by a static eliminating charger 21a, and the remaining toner and the like are scraped off by a cleaning brush 22a, and the cycle from charging is repeated again. Original picture 5
While moving on the upper plate 7 by the contact glass 4, the slits 8a,
The toner particles are sequentially irradiated through 8b and 8c, reach the photoreceptor drum via the respective filters 10a, 1ob, and 10c, and form a toner image on the drum in the process described above.

The obtained toner images are transferred to transfer positions 20a and 20b of each drum.
, reaches 20c. In synchronization with this, the transfer paper 1 is supplied by the guide plate 25 and the pinch roller 26, is conveyed by the transfer belt 19, and reaches the transfer positions 20a, 20b, 20c of the first, second, and third drums. Registered toner images of each color are transferred in a sequentially stacked manner.
The transfer paper 1 having the transferred toner image is peeled off from the transfer belt 20 by a peeling claw 27, and finally transferred to a fixing device 28.
The image is fixed and made into a permanent visible image before being discharged. In this type of multicolor electrophotography, toner images of three or four colors are sequentially transferred from each photoreceptor drum as described above, and the toner images are superimposed to form an image.
Despite the great advantage of avoiding mixing of toners of different colors, when the transfer paper is separated from one drum to the next and during transportation, the transfer paper may shift and the image may be misaligned. There is a big problem in that it is impossible to obtain a good color image. SUMMARY OF THE INVENTION It is an object of the present invention to provide a multicolor electrophotographic transfer method that eliminates the above-mentioned drawbacks and quickly superimposes toner images without positional deviation. Another object of the present invention is to provide a multicolor electrophotographic transfer method that is free from positional deviation and has high transfer efficiency. In FIG. 1, a transfer paper 1 is conveyed by a belt 19 via a guide plate 25 and a pinch roller 26 by a paper feed roller 2.

The belt 19 is formed of a dielectric material such as a polyester film or a polypropylene film, and is stretched between the rollers 14, 15, 16, 17, and 18 and is driven by these rollers. At the transfer positions 20a, 20b, 20c of each photoreceptor drum, transfer corona chargers 23a, 23b, 23c are arranged on the back side of the belt, and at the same time, they provide a bias effect during transfer, and at the same time, the transfer paper on the belt is closely supported on the conveyor belt 19 by electrostatic force. The transfer paper 1 on which a color image has been formed by sequentially stacking toner images at 20a, 20b, and 20c is peeled off by a peeling claw 27 and sent to a fixing section.

The conveyor belt 19 is driven in the direction of the arrow, and is neutralized by a neutralizing charger 24 provided at a position facing the roller 18 .

In this case, it is not necessary that the charge on the belt be completely removed by the charger 24; on the contrary, it is preferable to leave some charge because the transfer paper fed from the pinch roller 26 can be immediately brought into close contact with the belt. In this sense, it is also beneficial to use an AC corona charger or the like as the charger 24. Further, it is sufficient to apply a charge to the charger 23a that has the same polarity as the charge on the photoreceptor drum 3a and is larger than the amount of charge, and in this device, a voltage of about 4.0 KV is applied. This gives it a positive charge.

FIG. 2 shows a transfer method in which the transfer efficiency is further improved in the transfer method of the present invention. That is, this transfer method is similar to the transfer method shown in FIG. 1, in which a charger for eliminating electricity is disposed between the first drum and the second drum, and between the second drum and the third drum. In the transfer method shown in FIG. 1, the transfer position 20a (20a on the second drum
b. In the third drum, the transfer paper 1 on which the toner image has been transferred in step 20c) is in close contact with the conveyor belt 19, so when it is peeled off from the photoreceptor, a peeling discharge causes a charge of the toner and a homogeneous charge on the transfer paper. The toner is charged, and correspondingly a charge of opposite polarity to that of the toner is generated on the belt on the side of the transfer corona charger. As a result, the transfer efficiency decreases when transferring at subsequent transfer positions of the photoreceptor drum. In the present invention, as described above, a defrosting charger is provided between each photoreceptor drum to reduce the amount of charge on the transfer paper, thereby preventing a decrease in transfer efficiency. The neutralizing chargers 29 and 30 can also be AC corona chargers like the charger 24. As explained in detail above, in the transfer method of the present invention, a corona charger is provided opposite the transfer position of each photoreceptor drum, and the transfer paper is transferred while being brought into close contact with the conveyor belt, so that there is no space between each photoreceptor. Transfer images can be quickly obtained without positional deviation.

It has been experimentally confirmed that in the corona charger 23 of the present invention, even better results can be obtained by increasing the applied voltages in the order of a, b, and c.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are layout diagrams of multicolor electrophotography in which the transfer method of the present invention is implemented. 1... Transfer paper, 3... Photosensitive drum, 19
...Transport belt, 20...Transfer position, 23
...Corona charger, 24... Charger for static elimination, 29, 30... Charger for static elimination. Figure 1 Figure 2

Claims (1)

[Claims] 1. Perform optical scanning on a color original image to form an optical image, and project this optical image via an optical device and a filter for each color onto a charged photoreceptor for each primary color to form an electrostatic latent image, In the multicolor electrophotography method in which this latent image is visualized and then the thus visualized image is sequentially transferred onto transfer paper, the transfer paper is moved to the transfer position of each photoreceptor using a single endless belt. A transfer method for multicolor electrophotography, characterized in that the transfer belt is conveyed through the transfer belt, corona charging is applied from the back side of the conveyor belt at each transfer position, and charging for static elimination is further performed between the transfer positions of each photoreceptor.