JPS6010625B2 - Transfer method in multicolor electrophotography - Google Patents

Description

[Detailed description of the invention] The present invention relates to a transfer method in multicolor electrophotography.

A plurality of photoconductors, each equipped with a different filter, are placed side by side, and these photoconductors are charged, exposed through the attached filters, developed, transferred, etc. In this case, each color image is transferred by a belt. A multicolor electrophotographic method performed on paper in circles has already been proposed.

In this multicolor electrophotographic method, a belt made of an insulating material is used, and when transferring a powder image formed on a photoreceptor,
Generally either corona discharge transfer or bias roller transfer is used. Whichever transfer method is used, the first
A good transfer result is obtained at the transfer position of the photoconductor of the second color, but uniform transfer is not performed at the transfer position of the photoconductor of the second color or lower. This is considered to be due to the following reasons. When the transfer paper is peeled off from the photoreceptor immediately after transfer, a separation discharge occurs, and the transfer paper becomes electrically charged due to this separation discharge.Since the belt is an insulator, this electrical charge cannot escape. Retained. This is considered to be because if the next transfer is performed in this state, the electric field due to the next transfer charge is canceled out by the above-mentioned charges, or the transfer charge is difficult to occur. For example, in the above-mentioned multicolor electrophotography method, corona discharge transfer is used, and a polyethylene terephthalate 7 film having a thickness of 125 mm is used as the conveyor belt for the transfer paper.5.
A discharge occurred from the back side of the belt at the voltage of Uta V. The belt feed rate was 100 Y/sec. After the first color was transferred, it was confirmed that a -1500V electric bowl was placed on the film, and uniform transfer was not performed for the second and subsequent colors. The present invention aims to eliminate the above-mentioned drawbacks in multicolor electrophotography of the initially mentioned type.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

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

Images are transferred onto the fed transfer paper by a number of photoreceptor drums corresponding to the number of color separations, three photoreceptor drums 3a, 3b, and 3c in the figure. The same structural elements are attached to the first photosensitive drum 3a, the second drum 3b, and the third drum 3c for processing each process from exposure to transfer. In order to simplify the explanation, the first drum 3a will now be explained, but in the figures, the same symbols represent the same elements, a for those belonging to the first drum, b for those belonging to the second drum, and b for the third drum. Items belonging to ``c'' shall be identified by adding the symbol ``c''. An upper plate 7 on which a lamp 6a, for example a halogen lamp, for illuminating the original 5 placed on the contact glass 4 guides the contact glass 4.
The original 5 is irradiated through a slit 8a provided in the
It is placed at a position suitable for exposing the drum 3a.

In the original 5, the reflected light is filtered through a blue filter 10a (lob is a green filter) by a lens ga.
10c 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 an electrostatic image. This static exposure latent image is developed with yellow toner (magenta toner in 13b, cyan toner in 13c) in the developing device 13a, and is brought into contact with the belt 19 stretched between rollers i4, 15, 16, 17, and 18. - The toner image is transferred onto the transfer paper 1 being conveyed by the belt 19 at the transfer position 20a. The belt 19 is ``as described later,
A material made of a material with zero resistance and low resistance is used. 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 starts again from charging. Manuscript 5
While moving over the upper plate 7 from the contact glass 4, the slit 8a is illuminated by each illumination lamp 3a, 6b, 6c.
, 8b, 8c, and reaches the photosensitive drum via the respective filters 10a, 10b, 10c, forming a toner image on the drum in the process described above.

The obtained toner images are transferred to transfer positions 20a and 20 of each drum.
b, reaches 20c.

At the same time, the transfer paper is moved between the guide plate 28 and the pinch roller 2.
9 and conveyed by a transfer belt 19 to transfer positions 20a, 20b, 2 of the first, second, and third drums.
The transfer paper 1, on which the toner image of each color has been transferred after reaching 0c, is peeled off from the transfer belt 19 by a peeling claw 27, and finally fixed by a fixing device 26 to become a permanently visible image and discharged. be done. Finally, residual potential is removed from the transfer belt 19 by a charger 23 for neutralization. As the charger 23, an AC corona charger can be used. At each transfer position 20a, 20b and 20c,
Transfer rollers 24a, 24b, and 24c made of metal, conductive rubber, or the like are arranged on the back side of the belt 19 so as to lightly press the belt 19 onto each drum. A bias voltage having a polarity opposite to that of the toner is applied to each of these transfer rollers by bias voltage sources 25a, 25b, and 25c. In this case, the bias voltage should be 100V or higher and can be changed arbitrarily depending on the toner transfer.
Further, it is sufficient that each transfer roller presses the belt 19 so that it does not move relative to each drum 3a, 3b, and 3c. FIG. 2 shows a device in which corona chargers 30a, 30b, 30c are used instead of transfer rollers 24a, 24b, 24c.

Other points are the same as the embodiment shown in FIG. The transfer belt 19 in each embodiment shown in FIGS. 1 and 2 is as follows:
According to the present invention, the material is made of a material having a specific resistance of 1 to 1 to 3Q. When the resistance of the transfer belt is reduced in this way, the discharged charges are neutralized on the back and front sides of the belt, the potential on the belt becomes smaller, and uniform transfer is performed for the second and subsequent colors. If the resistance of the transfer belt 19 becomes too low, the transfer rollers 24a,
24b, 24c or co. Na charger 30a, 30b, 30
Transfer Teiden by c becomes ineffective and transfer efficiency deteriorates. An example of manufacturing the above transfer belt 19 according to the present invention is as follows.

Put the following components of polyester resin, 100% carbon black, 2.3% methyl ethyl ketone, and 500% into a pole mill.
Distribute well throughout the day and night.

Next, this is poured onto a glass plate to a thickness of about 100 r. The specific resistance of the belt thus obtained was approximately 1 and IQ arc. Furthermore, the specific resistance of each belt obtained by the same processing method as in the above example with various amounts of carbon black relative to the polyester resin, and the results of multicolor electrophotographic copying performed using these belts are shown.

However, the linear speed of the photoreceptor drum and therefore the transfer belt is low.
The charging voltage of the photoreceptor drum is 14 mm/sec. Song V, and transfer voltage is 15. It was the song V. In this example, when belts with specific resistances of 1 to 1 and 30 arc were used, at least the toner images on the first drum, second drum, and third drum were transferred to the transfer paper.

Therefore, when obtaining a multicolor copy, for example, natural color reproduction can be obtained by adjusting the toner density. From this, it can be seen that the specific resistance of the belt material that can be transferred by a continuous belt is considered to be in the range of 1 to 3. As described above, the transfer method according to the present invention eliminates the adverse effects caused by peeling discharge during transfer of the second and subsequent colors, and ensures uniform transfer of the second and subsequent colors.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a multicolor electrophotographic copying machine to which the transfer method of the present invention can be applied, and FIG. 2 is an explanatory diagram showing a modification of the same copying machine. 1... Transfer paper, 3a, 3b, 3c... Photosensitive drum, 10a, 10b, IOC... Filter, 1
9...Transfer belt. Figure 1 Figure 2

Claims (1)

[Claims] 1. A plurality of photoreceptors, each equipped with a different color filter, are arranged side by side, and these photoreceptors are charged, exposed through the attached filters, developed, transferred, etc. In this case, the image of each color is transferred by a belt. In a multicolor electrophotographic transfer method in which transfer is performed sequentially on the same transfer paper under voltage application, the belt has a specific resistance of 10^8 to
A transfer method characterized by using a material of 10^1^3 Ωcm.