JPH0221583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel image forming method that can provide a simple and stable copying device that can be used in copying devices, printers, and the like.

2. Description of the Related Art Conventionally, as an image recording method that can use plain paper in devices or printers for copying images, documents, etc., there is an electrophotographic method called the Carlson method that uses a photoreceptor repeatedly. In this method, a photosensitive layer made of a photoconductor is charged, an electrostatic latent image formed by imagewise exposure is developed with toner, and the image is transferred and fixed onto a transfer paper. After the toner image is transferred, the photoreceptor is cleaned and used repeatedly. In this method, the recording paper on which the final image is obtained is plain paper, so the image does not change over time, and a high-quality image is maintained semi-permanently.

However, this method generally requires that the photoreceptor be uniformly charged in advance. Therefore, a charging device such as a corona charging device is required, and the entire device becomes complicated. Furthermore, when a corona charging device is used as the charging device, reliability of image quality is lowered due to deterioration of the photoreceptor due to the generation of ozone, generation of charging unevenness due to toner adhesion to the corona charging device, and the like.

In order to improve the problems of the Carlson method, a method called charge development method has been proposed as a method that does not use a corona charger. In this method, a photoreceptor with sustained photoconductivity is irradiated with light to form an electrical latent image with different conductivity in image areas and non-image areas, and then a voltage is applied to conductive toner or semiconductive toner. A toner image is formed on a high-resistance portion on the photoreceptor by bringing the toner into contact with the electrical latent image. Since this method does not use a corona charger, the problems of the Carlson method described above are solved, but since a continuous photoconductor is used as a photoreceptor, there is a problem in repeated use. That is, if after one exposure to form an image, the next exposure is carried out before the sustained photoconductivity is restored.
Unable to obtain good images. Additionally, this method requires that the photoreceptor be persistently photoconductive, which limits the type of photoreceptor that can be used.

An object of the present invention is to provide an image forming method that eliminates the drawbacks of the electrophotographic method and does not use a corona charger.

Another object of the present invention is to provide an image forming method in which a photoreceptor can be easily used repeatedly. A further object of the present invention is to provide an image forming method capable of obtaining copies with good sensitivity and no fog.

The image forming method of the present invention achieves the above-mentioned object by performing development simultaneously with exposure from the back side of the photoreceptor.

The present invention will be explained in detail below based on the drawings. FIG. 1 is a sectional view of a comparison photoreceptor for comparing the basic structure of the photoreceptor used in the present invention. Photoreceptor 1
consists of a transparent conductive substrate 2 and a photoconductive layer 3.
FIG. 2 is a sectional view showing the basic structure of a photoreceptor used in the present invention. The photoreceptor 1 includes a transparent conductive substrate 2,
It consists of a transparent insulating layer 4 and a photoconductive layer 3. As the transparent conductive substrate 2, a transparent conductive layer such as SnO ₂ or In ₂ O ₃ is deposited on a transparent substrate such as transparent glass or a transparent resin film, or a transparent conductive layer such as Sn ₂ O ₃ is coated with a resin. Can be used dispersed inside. The photoconductive layer 3 may be a layer in which fine powder of an inorganic photoconductor such as zinc oxide or cadmium sulfide is dispersed and applied in a binder, or an inorganic photoconductive layer such as amorphous Se, Se alloy, or amorphous Si. A layer in which the material is vacuum-deposited, a layer in which a eutectic or aggregate of thiavirylium salt and polycarbonate is dispersed and applied in a polycarbonate/triphenylmethane derivative matrix, a layer in which polyvinylcarbazole and trinitrofluorenone are mixed and dissolved and applied, etc. Organic photoconductive layers can be used. In the photoreceptor used in the present invention, as shown in FIG. 2, a transparent insulating layer 4 is provided on a transparent conductive substrate 2, and then the photoconductive layer 3 is provided thereon. In this case, as the transparent insulating layer, urethane resin, epoxy resin, polyester resin, polycarbonate resin, cellulose acetate resin, etc. can be used. By providing the transparent insulating layer 4, fogging is improved.

Next, in order to briefly explain the principle of the image forming method according to the present invention, first, a third image forming method using a comparative photoreceptor will be explained.
This will be explained using figures.

The developing roller 5 has a magnet inside and holds magnetic conductive toner 6 on its surface. As the toner, one that exhibits conductivity or semi-conductivity with a resistance value of 10 ¹⁰ Ωcm or less can be used. Magnetic conductive toner 6
is in contact with the photoconductive layer 3 while being electrically connected to one terminal of the power source 7 . The other terminal of the power source 7 is electrically connected to the transparent conductive layer of the photoreceptor 1. In the above state, light from the lamp 10 is irradiated onto the photoreceptor 1 from the transparent conductive layer 2 side of the photoreceptor 1 through the slit 8 and the document 9, and at the same time, the magnetic conductive toner 6 is rubbed on the surface of the photoreceptor. When the photoreceptor 1 and the original 9 are moved in the direction of the arrow in the figure, toner adheres to the photoreceptor corresponding to the image area (unexposed area) of the original 9. Since the image area of the photoreceptor is not exposed to light, the surface resistance of the photoreceptor is high, and the charged toner adheres to the photoreceptor due to electrostatic force. On the other hand, since the non-image area of the photoreceptor is exposed to light, the surface resistance of the photoreceptor decreases, and the amount of charge of the toner decreases, so that the toner does not adhere to the photoreceptor.

When using a photoreceptor having a transparent insulating layer as shown in FIG. 2 used in the present invention, image formation can be carried out in a similar manner. The voltage applied to the conductive toner is selected from −2000 to +2000 V depending on the characteristics of the toner used, photoreceptor, etc.

According to the method of the present invention, since development is carried out simultaneously with exposure from the back side of the photoreceptor, it is possible to use not only a persistent photoconductor but also a non-persistent photoconductor photoreceptor.
Therefore, material selection for the photoreceptor becomes easy. Furthermore, by using a non-persistent photoconductor (or a photoconductor with a significantly short duration), it is possible to obtain images with little deterioration even after repeated use. moreover,
Since voltage is applied to the photoreceptor by the developing roller at the same time as exposure, it is possible to obtain images with good sensitivity and no fog. In particular, since a photoreceptor with a transparent insulating layer is used, the charge transferred from the toner to the photoreceptor in the exposed area does not escape to the ground substrate due to the influence of the insulating layer, so the potential of the photoreceptor increases and the electric field acting on the developing toner becomes weaker. , toner is less likely to adhere to the photoreceptor, and good images without fogging can be obtained.

The image forming method of the present invention will be explained below with reference to Examples and Comparative Examples.

Comparative Example A solution containing equimolar amounts of polyvinylcarbazole and trinitrofluorenone was mixed and dissolved on a transparent conductive substrate with a thin layer of In ₂ O ₃ deposited on a transparent polyester film, and a dry film thickness of about 5μ was obtained. A photoconductor was provided with a photoconductive layer.

The transparent conductive layer of this photoconductor is grounded, and a voltage of 100V is applied to the conductive magnetic toner held on a developing roller equipped with a magnet inside, image exposure is performed from the back side of the photoconductor, and at the same time the above development is performed. When the magnetic conductive toner on the roller was brought into contact with the photoconductive layer of the photoreceptor and rubbed, transferred and fixed, a good image was obtained.

Example: A urethane resin (Rethane 4026, manufactured by Kansai Paint) was applied to a transparent conductive substrate with a thin layer of In ₂ O ₃ deposited on a transparent polyester film, and the dry film thickness was approx.
A transparent insulating layer with a thickness of 1μ is provided, and a solution containing equimolar amounts of polyvinylcarbazole and trinitrofluorenone is coated on top of the transparent insulating layer to give a dry film thickness of approx.
A 5μ photoconductive layer was provided to form a photoreceptor.

The transparent conductive layer of this photoconductor is grounded and held on a developing roller equipped with a magnet inside, and a voltage of 100V is applied to the conductive magnetic toner, image exposure is performed from the back side of the photoconductor, and at the same time, When the magnetic conductive toner on the developing roller was brought into contact with the photoconductive layer of the photoreceptor and rubbed, transferred, and fixed, a good image was obtained, with less fog than in the comparative example.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a comparative photoreceptor, and FIG. 2 is a schematic sectional view of an example of a photoreceptor used in the present invention. FIG. 3 is a diagram for simply explaining the principle of the image forming method of the present invention, and shows a diagram using the comparative photoreceptor shown in FIG. 1. Symbols in the figure: 1...photoreceptor; 2...transparent conductive substrate;
3... Photoconductive layer; 4... Transparent insulating layer; 5... Developing roller; 6... Magnetic conductive toner; 7... Power supply; 8... Slit; 9... Original; 10... Lamp.

Claims (1)

[Claims] 1 A photoreceptor consisting of a transparent conductive substrate, an insulating layer, and a photoconductive layer is sequentially provided with the conductive or An image forming method characterized by rubbing a semiconductive magnetic toner on the surface of a photoconductive layer of a photoreceptor so that the toner adheres to non-exposed areas.