JPS58102256A - Image forming method - Google Patents

Abstract

PURPOSE:To form toner images like sharp image patterns easily by using the developer consisting of at least two components of the 1st particles having conductivity and magnetism and having a visual color and the 2nd particles having a color differing from the same. CONSTITUTION:DC bias is applied between a sleeve 5 and a transparent conductive substrate 12 of a photoreceptor by using the developer mixed with the 1st particles 6a of a certain color and the 2nd particles 6b which are smaller in grain sizes than said particles, have about the same conductivity and magnetism as those of the 1st particles and have a different color. Picture light is exposed to the position where the developer and the photoreceptor contact. In the non- picture parts, that is, in the dark parts D, the electric field is weak and if the 2nd particles 6b stick on the photoreceptor, the 1st particles 6a hardly stick thereon, but in the bright parts L, negative charge is generated on the surface of the photoreceptor to obtain the strong electric field and the 1st particles 6a having relatively large grain sizes stick sufficiently on said parts as well. The images formed in such a way are substituted by the another color in the fogged parts of the base to obtain the sharp pictures.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming scratches, and more particularly to a method of forming a toner film on a photoreceptor.

Conventionally, as a method of forming toner on a photoconductor, the photoconductor is uniformly charged and the photoconductor is irradiated with original image light or image light from a signal-modulated light beam. A method is known in which electrostatic latent scratches are formed by creating a difference in charge density in a pattern on the substrate, and the electrostatic latent scratches are developed using an insulating or conductive developer. In this method, if an insulating developer is used, it can be mixed with other particles and triboelectrified on the developer sleeve, or the developer can be attached to the friction band by contact with the developer sleeve. Visual image. In addition, when using a conductive developer, the electric charge existing on the photoconductor induces charges in the developer on the grounded developer sleeve that should pair with the charges on the photoconductor, and the developing The developing agent is deposited on the surface of the photoreceptor by the Coulomb force acting between the agent and the photoreceptor to form a visible image.

When using either an insulating or conductive developer, so-called background fog may occur, but this often occurs when charges that should be removed during image exposure remain. In order to eliminate this background gap, the developing device 17 is designed to prevent a potential difference from occurring between the white background portion on the photoreceptor and the developer attached to the developing device sleeve during development.

may bias the waveform positively or negatively.

Hereinafter, this wound forming method will be referred to as the first method.

Alternatively, as shown in FIG. 1, a photosensitive layer 1 is provided on a transparent conductive substrate in which a transparent conductive layer 2 and a transparent support 3 are laminated to form a photoreceptor, and a conductive magnetic developer 6 is uniformly formed by a magnetic field. A DC bias is applied from the power source 4 between the adhered developer sleeve 5 and the transparent conductive substrate of the photoreceptor to form a uniform potential difference between the developer and the surface of the photoreceptor. An image pattern is formed on the surface of the photoreceptor by atomizing the image light P from the image light irradiator 13 to the position where the conductive developer on the developer sleeve is guided to the surface of the photoreceptor from the transparent conductive substrate side of the body. It is possible to form a toner image of the following shape. Hereinafter, this method of developing greatness will be referred to as the second method.

The first method described above requires equipment such as control means and high-voltage generators for the process of charging, exposing, and developing, making the equipment complicated and expensive, and it also becomes less reliable. It has the following drawback.

The second method does not require a charging process and has the advantage that the equipment can be extremely simple compared to the first method, but on the other hand, it is important to produce background fog in order to obtain sufficient image density. absolutely unavoidable.

That is, in the second method, the process in which the developer adheres to the surface of the N-type photosensitive layer is as shown in FIGS. A conductive magnetic developer is introduced onto the surface of the photoreceptor while applying a DC bias such that the sleeve side is positive between the developing sleeve 5 and the transparent conductive layer 2, and the contact between this developer and the surface of the photoreceptor is By forming a uniform potential difference between them and simultaneously irradiating image light from the transparent conductive substrate side, the nine layers 1
According to the photo carriers 8 generated and moved in an image pattern within the sleeve, positive charges 7 are induced in the conductive developer 6 held in the sleeve, generating a strong electric field, and due to Coulomb force, as shown in FIG. A developing agent 6 is deposited on the surface of the photoreceptor to form a toner image. In this case, even in the dark and non-image areas, charges 9 and 10 are already induced by the capacitance of the area including the dark photosensitive layer between the conductive developer and the transparent conductive substrate, and a weak electric field exists. Therefore, the Coulomb force acts also on the valve surface image portion, and the developer 6 adheres to the surface due to the force of the oscillation, causing a background cover υ.

Note that although an N-type photosensitive layer is used as an example here, similar results can be obtained even if other photosensitive layers are used by selecting the polarity of the DC bias applied between the sleeve and the transparent conductive substrate. In other words, when using a P-type photosensitive layer, apply a DC bias so that the sleeve side is negative, and when using a bipolar or P-type, N-type composite photosensitive layer, select the polarity of the DC bias as appropriate. do it.

Here, by reducing the direct current applied to the sleeve and substrate, the absolute toner density in the background fogging area can be made sufficiently low, but even in the so-called bright areas of the image pattern, there is sufficient photocarrier inside the photoreceptor. As a result, the entire toner image that should be deposited in a turn shape cannot obtain sufficient density.Therefore, as mentioned above, the second method has advantages over the first method. While having.

The main reason why this method is not widely used as a method for forming toner images on the surface of a photoreceptor is the background fog that is thought to occur in principle as described above.

The present invention has been proposed in view of the above, and allows the user to freely select the base of a turn-shaped image so that a toner image with a clear image pattern can be easily obtained and background fog does not become a problem. The purpose of the present invention is to provide a method for forming a wound.

As a means for this, the present invention provides first particles that are electrically conductive and magnetic and visually have a certain color, and the first particles that are relatively easier to adhere to the surface of the photoreceptor than the first particles in the valve surface image area.
a developer consisting of at least two components: particles of color and particles of color different from color, a developer carrier having a magnet inside and holding the developer on its outer surface; A photoreceptor using a connected electrode and a photoreceptor having a transparent conductive substrate, applying a DC bias between the electrode and the photoreceptor to guide a developer to the surface of the photoreceptor, and simultaneously guiding the developer. irradiating the body position with image light from the transparent conductive substrate side;
It is characterized by attaching a developer to the surface of the photoreceptor.

Examples of the present invention will be described below.

Example 1 First conductive magnetic particles 6a of a certain color as shown in FIG.
and second particles 6b which are smaller in particle size, have conductivity and magnetism comparable to those of the first particles, and have a different color.
A sleeve 5 as an electrode electrically connected to this developer, and a transparent conductive substrate 1 of a photoreceptor.
A DC bias is applied by a power source 4 between the developer and the photoreceptor, and image light is exposed to the position where the developer and the photoreceptor are in contact. In the valve surface scratch line, that is, in the dark area, as shown in FIG. 4(a), there is no negative charge on the surface of the photoreceptor, so the electric field is weak, and as shown in FIG. 5(a), the electric field is weak. 20 particles 6b, that is, particles with a small particle size, tend to adhere, and once the second particles 6b adhere to the photoreceptor, the first particles 6a, which have a larger particle size, hardly adhere.

However, in the bright area, as shown in Figure 4 (Φ), negative charges are generated on the surface of the photoreceptor, so the electric field is strong, and in this area there are relatively large particles of relatively large size, as shown in Figure 5 (b) K. Particles 6a4. Adheres well. 1ard<(/fJtlVtThe photoreceptor shown in FIGS. 4 and 5 has a photosensitive layer 11 laminated on a transparent conductive substrate 12, and the photosensitive layer is an N-type photosensitive layer. , a P-desensitized layer, a bipolar photosensitive layer, or a P-type and N-type composite photosensitive layer, and the polarity of the DC bias can be selected depending on the type of the photosensitive layer. The background part is replaced with a different color, making it possible to obtain a clear image.

Example 2 A developer is used in which the first particles 6a are mixed with second particles 6b having different magnetism and color from the first particles. If the second particles 6b are particles that have weaker magnetism than the first particles 6a or particles that have no magnetism, the force with which they are held by the developer carrier 5, which has a magnet inside, will be weaker. Therefore, the second particles 6b are more likely to adhere to the photoreceptor surface than the first particles 6a at the valve surface scratch line, that is, in the low electric field region, and the photoreceptor surface at the valve surface scratch line is as shown in FIG. 5(a). It is covered with second particles 6b as shown in FIG. On the other hand, since the electric field is strong in the drawing area, the first particles 6a, which have relatively strong magnetism, can be sufficiently attached as shown in FIG. 5(b). Therefore, the background cover caused by the first particles 6a is eliminated, and a clear image can be obtained.

Example 3 A developer is used in which the first particles -f6m are mixed with second particles 6b which are different in conductivity and color from the first particles. Assuming that the second particle has a relatively large electrical conductivity compared to the first particle, a larger amount of electric charge is induced in the second particle 6b for the same electric field. The second particles 6b adhere to the surface of the photoreceptor more easily than the particles 6a, and as described above, the surface of the photoreceptor is covered with the second particles 6b at the valve surface area. . On the other hand, since the electric field is strong in the image area, the first particles 6a can also be sufficiently attached. Therefore, a high-quality image can be obtained without the background cover and blemishes caused by the first particles 6a.

Example 4 It is assumed that the second particles 6b are insulating and have a different color from the first particles 6a. In this case, in order to electrically attach the second particles 6b to the surface of the photoreceptor, the first particles 6a
Frictional charging is performed by mixing with

Therefore, the developer consists of the second charged particles 6b and the first particles 6a, which are caused to have stain charges by the electric field.
are mixed. In this case, the second particles 6b, which have a weak electric field and are originally charged, are more likely to adhere to the surface of the photoreceptor, and the surface of the photoreceptor corresponding to the valve surface scratch line is covered with the second particles 6b.

On the other hand, in the image area, sufficient charges are induced in the first particles 6a due to the strong electric field, and the first particles 6a can also be sufficiently attached to the surface of the photoreceptor. Therefore, the background fog caused by the -th particles is eliminated, and a clear image can be obtained. For example, when using an N-type photosensitive layer, the above-mentioned DC bias is applied so that the photoreceptor side becomes negative, and in this case, the second particles 6b are positively charged by friction, and the P-type photosensitive layer When using a tortoise that is negatively triboelectrically charged.

As described above in Examples 1 to 4, the adhesion force of the particles can be changed by changing the conductivity, magnetism, particle size, etc. of the particles when adhering them to the surface of the photoreceptor. Here, for the first conductive magnetic particle,
The second particles may have one or more of their conductivity, magnetism, or particle size changed, or they may be changed in an appropriate combination of these properties to make the image clearer. It is even more effective.

For example, if chargeable, insulating, non-magnetic particles are selected as the second particles, an appropriate resin can be used as the particles, and the color of the particles can be freely determined using a dye.

In order to impart magnetism to the particles of the developer used in the present invention, magnetic powder such as black magnetite or slightly reddish γ-^, matite, ferrite, etc. is included in the particles. In addition, to make the particles conductive, black carbon black, or tin oxide, which is almost transparent when made into a thin film, or indium oxide, which is a conductive powder, is attached to the particle surface.To choose the color to 0%, blue dye is used. , red dye, yellow dye, or other dyes or pigments are included in the particles.

K, which is actually used to make particles, is prepared by mixing resin with the above-mentioned magnetic powder, dye, or pigment, heating, melting, cooling, and then pulverizing it into particles. In order to impart electrical conductivity, electrically conductive powder is mixed with the pulverized particles and heat treated to adhere the electrically conductive powder to the surface of the particles. Now, when using conductive magnetic particles made of blue dye, black magnetite, and black carbon black as the first particles,
.

In order to change the color of the second particles from the first particles, for example, red dye, reddish hematite, or almost transparent tin oxide or indium oxide may be appropriately selected as the material. Also, to change the degree of conductivity,
The amount of conductive powder to be attached to the particle surface may be changed, and the degree of magnetism can be changed by appropriately changing the amount of magnetic powder to be mixed. particles are obtained.

In addition to the second particles mentioned above, when using a developer with insulating and non-chargeable granules as the second particles, it is possible to avoid the electrical adhesion force as described above, and to The second particles tend to adhere to the flaw line on the valve surface due to the adsorption force caused by the van der Waals force with the surface, and the same effects as described in 1 to 4 above can be obtained. If you use it, the effect will be tremendous.

As described above, the present invention is a method for forming a toner film on a photoreceptor in electrophotography, and it is possible to obtain a toner film with a clear pattern using an extremely simple method, and there is no problem with background fog. A sleeping effect can be obtained by freely selecting the base of the patterned image.

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams of the process of attaching a developer to the surface of a photoconductor using a conventional image forming method, and FIG. 4 is an illustration of a process of attaching a developer to the surface of a photoconductor using the image forming method of the present invention. FIG. 5 is an explanatory diagram of a state in which a developer is adhered to the surface of a photoreceptor by this method. 1 is a photosensitive layer, 2 is a transparent conductive layer, 3 is a transparent support, 4 is a DC power supply, 5 is a developing sleeve, 6 is a conductive developer, 7 is a charge, 8 is a photo carrier, 9.10 is a charge , 6a is a first particle, 6b is a second particle, 11 is a photosensitive layer, and 12 is a transparent conductive substrate.

Claims (1)

[Claims] (1) The first particles have conductivity and magnetism and visually have a certain color. a developer consisting of at least two components of second particles having different colors; a developer carrier having an internal vertical magnet and holding the developer on its outer surface; and an electrode electrically connected to the developer. and,
A photoreceptor having a transparent conductive substrate is used, a DC bias is applied between the electrode and the photoreceptor to guide the developer to the surface of the photoreceptor, and at the same time, the transparent conductor is applied to the photoreceptor at the position where the developer was introduced. A scratch forming method characterized by irradiating image light from the substrate side and causing a developer to adhere to the surface of the photoreceptor.