JPH0746245B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In an image forming apparatus provided with a means for photo-erasing a photoconductor on which at least latent image charges are formed, a photo-erasing bias is applied across a photoconductor at a position facing the photo-erasing means. Means are provided so that the charge can be sufficiently discharged by applying a charge-eliminating bias voltage having a polarity opposite to the polarity of the latent image charge from the photoconductive layer side upon irradiation with the charge-eliminating light.

[Industrial application field]

The present invention relates to an image forming apparatus that forms a toner image on a bright portion on a photoconductor irradiated with image light and transfers the toner image to a display or recording paper.

Current copiers or high-speed, high-print quality printers generally use an electrophotographic recording system. This system is a so-called Carlson process in which recording is performed in the steps of uniform charging, image exposure, development, transfer, fixing, charge removal, and cleaning.

In the Carlson process, a corona discharger is used for uniform charging and static elimination. Since the corona discharger is configured to apply a high voltage of several KV to the corona wire, it requires a high-voltage power source and is easily affected by humidity, dust, etc., and therefore has a drawback of low reliability. Further, ozone generated in a corona discharger produces an odor, and in recent years, ozone is harmful to humans.

Further, since the above-mentioned seven steps are required, there is a drawback that the device becomes complicated and the size becomes large.

In view of the above-mentioned problems, an image forming method has recently been proposed in which a corona discharger is unnecessary and the device is downsized.

[Conventional technology]

 FIG. 2 shows the recording principle of the optical back surface recording method.

In the figure, the photoreceptor 1 is composed of a transparent substrate 1a, a transparent conductive layer 1b, and a photoconductive layer 1c, and the transparent conductive layer 1b is connected to the ground. The magnetic brush developing machine 2 provided on the photoconductive layer 1c side of the photoconductor 1 comprises a magnet roller 2a and a sleeve 2b, and the magnet roller 2a is freely rotatable. Further, a strip-shaped recording electrode 4 insulated from the sleeve 2b by an insulating film 3 is provided on the surface of the sleeve 2b. A voltage 6 having a polarity opposite to the carrier polarity (positive polarity in the figure) of the photoconductive layer 1c is applied to the recording electrode 4, and a voltage 7 having a polarity opposite to the recording electrode 4 is applied to the sleeve 2b. The developing device 2 is filled with a one-component developer or a two-component developer, and the developer 5 is conveyed in the direction of the arrow in the figure.

An image exposing means 8 is arranged on the transparent substrate 1a side of the photoreceptor 13. Examples of the image exposure means 8 include an optical system using an LED array, an optical system using a liquid crystal shutter, an optical system using electroluminescence, and an optical system using a laser. The image exposure means 8 is arranged so that the optical axis of the exposure light intersects the recording electrode 4.

Next, the principle of image formation will be described.

When the photoconductive layer 1c is imagewise exposed in the portion A of the apparatus having the above-described structure, photocarriers are generated in the photoconductive layer 1c. Carriers of the opposite polarity to the voltage 6 applied to the recording electrodes 4 of the photocarriers move to the vicinity of the surface of the photoconductive layer 1c and become latent image charges 10.
In this way, in the exposed portion, the electrostatic capacity of the photoconductive layer 1c apparently increases, so that the amount of adhered toner increases, and a toner image with a certain degree of contrast is formed between the exposed portion and the non-exposed portion.

Next, in the portion B, the reverse voltage 7 is applied to the sleeve 2b and the developer is accumulated, so that the excess toner in the non-exposed portion is collected in the developing device 2 by electrostatic force and magnetic force. At this time, the toner in the exposed area is also slightly recovered, but the latent image charge 10
Due to the electrostatic restraint force of the toner charge, most of the toner remains on the photoconductor 1 and a toner image 9 is formed.

On the other hand, an unnecessary toner image 9 ′ on the photoconductor 1 that has achieved a predetermined purpose, that is, a toner image that has been displayed by the image display device, a residual toner image after being transferred to recording paper in the image recording device, etc. When forming the image, the sleeve 2b
By the electrostatic force due to the reverse voltage of and the magnetic force of the developing machine, it is recovered by the developing machine and reused. In this way, the image exposure means 8
However, since it is on the opposite side of the developing device 2 with the photoconductor 1 interposed therebetween, the unnecessary toner image 9'can be collected and the image can be formed at the same time.

FIG. 3 shows a block diagram of a conventional image forming apparatus using the optical back surface recording method.

In the figure, the photoconductor film 11 is run by the feed roller 12 in the direction of arrow 31 in the figure.

A magnetic brush developing machine 13 is provided in the traveling path of the photoconductor film 11.
A recording electrode 15 is provided on the sleeve 13a and the magnet roller 13b with the insulating film 14 interposed therebetween. The recording electrode 15 and the sleeve 13a are respectively provided with a power source 16,
A bias voltage is applied by 17. The developer 18 is conveyed in the direction of arrow 28 in the figure by the rotation of the magnet roller 13b. Image exposure means 19 (LED19a Selfoc
The lens array 19b) sandwiches the photoconductor film 11.
It is installed so as to face the recording electrode 15.

The developed toner image 20 is transferred onto the recording paper 21 by the transfer roller 22 to which the transfer bias voltage is applied by the transfer bias power supply 23, and the toner image 24 on the recording paper 21 is fixed to the fixing device 25.
Is fixed to form a recorded image 26.

After that, the photoconductor film 11 is photo-erased by the static elimination lamp 28, and goes to the next process.

[Problems to be solved by the invention]

In the conventional static erasing device using the optical back surface recording method described above, since sufficient voltage is not applied between the surface of the photoconductor and the ground when the static eliminator is irradiated, the static charge is not sufficiently discharged, and latent image charges remain in the photoconductor. , Tends to appear as a toner image after development, acting as a latent image in the next process,
There have been problems such as impeding the improvement of print quality and causing a reduction in process speed due to the need for a process of re-electrification.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of performing sufficient charge elimination, improving application quality, and increasing process speed in view of the above-mentioned conventional problems.

[Means for solving problems]

As described above, the problem is that, as shown in FIG. 1, a neutralization bias applying means 40 is provided at a position facing the optical neutralization means 28 on the photoconductive layer 1c side across the photoconductor 11 and the surface of the photoconductive layer 1c is removed. Conductive layer
This can be solved by applying a charge-eliminating bias voltage during which the latent image charge 10 is directed toward the conductive layer 1b during 1b simultaneously with the irradiation of the charge-eliminating light.

[Action]

In the present invention, the photoconductive layer 1c is formed by the static elimination bias applying means 40.
A latent image charge 10 is applied between the surface and the conductive layer 1b in the direction of the conductive layer 1b. A charge-eliminating bias pressure is applied at the same time as irradiation of the charge-eliminating light. A problem that the residual latent image charge does not remain and tends to appear as a toner image after development in the next process, which hinders improvement of print quality, and a problem that causes a reduction in process speed due to the need for a re-charging process. It is possible to prevent the occurrence of such.

〔Example〕

FIG. 1 is an explanatory view of an embodiment of an image forming apparatus according to the present invention. The same parts as those in FIGS. 2 and 3 are designated by the same reference numerals and the description thereof will be omitted. 29 is a conductive roller. The one provided at a position facing the static elimination lamp 28 disposed on the photoconductive layer 1c side across the photoconductor 11, and 30 is a static elimination bias power source, which is provided to the photoconductor 11 via the conductive roller 29. Conductive layer 1c
A static elimination bias voltage is applied between the surface and the conductive layer 1b so that the latent image charge 10 is directed toward the conductive layer 1b.

With the configuration described above, it is possible to eliminate the residual latent image charges that are bound by the charges of the residual toner 27 more reliably than simply irradiating the latent image charge.

In the present embodiment, the case where the conductive roller 29 is used as the static elimination bias applying means has been described, but the present invention is not limited to this and may be a conductive brush, a contactor or the like. Is.

〔The invention's effect〕

As described above, according to the present invention, at the time of static elimination, the static elimination is sufficiently performed by applying the static elimination bias voltage at the same time as the static elimination light irradiation, and the problem due to the residual latent image charge can be suppressed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a diagram showing a recording principle of an optical back surface recording system, and FIG.
The figure is an illustration of a conventional image forming apparatus. In the figure, 1 and 11 are photoconductors, 2 and 13 are magnetic brush developing machines,
4, 15 are recording electrodes, 5 and 18 are developers, 6 and 6 are first voltage applying means, 7 and 17 are second voltage applying means, 8 and 19 are image exposing means, 28 is light removing means, Reference numeral 40 is a static elimination bias applying means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sumitaka Aida 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited (56) References JP 61-51169 (JP, A) JP 57-23964 (JP, A) JP 56-126856 (JP, A)

Claims (1)

[Claims] 1. A photoconductor (1) comprising at least a transparent or semitransparent conductive layer (1b) and a photoconductive layer (1c), and at least a developer disposed on the photoconductive layer side of the photoconductor. A magnetic brush developing machine (2) provided with a sleeve (2b) for carrying the recording medium, a recording electrode (4) provided on the sleeve (2b) so as to be insulated from the sleeve (2b), and the recording electrode (4). ) And a reservoir for the developer (5) provided downstream of the moving direction of the photoconductor (1), a first voltage applying means (6) for applying a voltage to the recording electrode (4), Second voltage applying means (7) for applying a voltage having a polarity opposite to that of the first voltage applying means (6) to the sleeve (2b).
And an image exposing means (8) provided on the side of the photoconductor (1) and the conductive layer (1b) and facing the recording electrode (4) for performing image exposure, and the photoconductive layer (1c). An image forming apparatus comprising a photo-eliminating means (28) disposed on the side of the photoconductor, the photo-erasing means (28) on the photoconductive layer (1c) side facing the photoconductor (1). A neutralization bias applying means (40) is provided at the position where the latent image charge (10) is applied between the surface of the photoconductive layer (1c) and the conductive layer (1b) toward the conductive layer (1b). An image forming apparatus characterized in that is applied at the same time as the irradiation of static elimination light.