JPS61159662A - Multi-color image forming method - Google Patents

Abstract

PURPOSE:To permit easy recording of multi-color images at a high speed without color deviation with one time of image exposure by using a photosensitive body laminated with different photosensitive layers via insulating layers and forming the multi-color images thereon. CONSTITUTION:The photosensitive body is constituted by superposing and disposing an insulating layer I1, red photosensitive layer PR, insulating layer I2, green sensitive layer PG, insulating layer I3, blue sensitive layer PB and surface insulating layer I4 on a conductive base body CB. The photosensitive body is electrostatically charged by a charger, then the charge of the polarity reverse from the electrostatic charge polarity is applied thereto simultaneously with image exposure to form color separated images as charge patterns on the photosensitive layers PR, PG, PB. The photosensitive body is then subjected to full- surface exposure by the light with which only the red sensitive layer PR has the photosensitivity. The photosensitive layers are then developed by a red toner. The layers are similarly developed by green and blue toners to form the multi-color images. The multi-color images are thus recorded onto a material to be transferred with one time of transfer.

Description

[Detailed description of the invention] B. Industrial application field The present invention relates to a multicolor image forming method.

Many methods and devices used therefor have been proposed in the past for the purpose of obtaining multicolor images using electrophotography, but they can generally be classified into the following types. One method is to repeatedly form a latent image using a photoreceptor and develop the color toner according to the number of colors separated, or to overlap the colors on the photoreceptor each time, or to transfer the colors to a transfer material each time the development is performed. This is a method of layering colors. Another method uses a device that has multiple photoreceptors corresponding to the number of separated colors, and simultaneously exposes each color light image to each photoreceptor, and the latent image formed on each photoreceptor is colored toner. A multicolor image is obtained by developing the image and sequentially transferring the images onto a transfer material to superimpose the colors.

However, in the first method described above, it is necessary to repeat the formation and development process of multiple latent images, and it takes time to record the image.
A major drawback is that it is extremely difficult to increase the speed. In addition, in the second method described above, multiple photoreceptors are used in parallel, so it is advantageous in terms of high speed, but since it requires multiple photoreceptors, an optical system, a developing means, etc., the apparatus is complicated.
It is large and expensive, making it impractical. Furthermore, both types have a major drawback in that it is difficult to align the image when image formation and transfer are repeated multiple times, and it is impossible to completely prevent color shift of the image.

In order to fundamentally solve these problems, it is sufficient to record a multicolor image on a single photoreceptor with one image exposure, but the reality is that such a system has not yet been developed.

C.6 Purpose of the Invention An object of the present invention is to provide a novel multicolor image forming method that can quickly and easily record a multicolor image without color shift through a single image exposure.

21 Structure of the invention, that is, the present invention has substantially no sensitivity in the visible light range consisting of at least wavelength ranges f and 1f;
A photosensitive layer P1 having a sensitivity substantially at I and a photosensitive layer substantially having a sensitivity at f2 are laminated with an insulating layer interposed therebetween, and a conductive substrate is placed on the side of the photosensitive layer P1. After applying image exposure from the photosensitive layer Pl side while discharging a photosensitive member having an insulating layer on the side; the entire lf1g light of the photosensitive member is applied with light that makes substantially only one of the photosensitive layers conductive. The present invention relates to a multicolor image forming method in which the steps of performing step 1 and developing with a toner of a color corresponding to the one layer of the photosensitive layer are repeated.

The conductive substrate includes one made of a conductive metal such as aluminum, or one made of plastic on which a surface layer made of, for example, aluminum is formed by vapor deposition or other means.

The photoreceptor used in the present invention has the following structure. That is, the photoreceptor is constructed by alternately laminating, for example, three or four insulating layers and two or three different photosensitive layers on a conductive neutral substrate.

For example, in the case where there are three photosensitive layers, one of these layers has photosensitivity to substantially only blue light, and the other layer has photosensitivity to substantially only green light, Yet another layer is photosensitive to substantially only red light. The insulating layers other than the bottom layer are translucent and may include color separation filters. Further, the bottom layer may not be provided.

The above-mentioned colors, green, and red all refer to colors that represent the three primary colors of light. Therefore, when blue, green, and red are described in the following description, these can be replaced with other three primary colors.
If blue, green, and red actually refer to the colors blue, green, and red, this shall be explained.

The photoreceptor is charged by a charger, and then, at the same time as the image is exposed, the band 'Il! Gives a charge of opposite polarity. As a result, a color separated image is formed in each photosensitive layer as a charge pattern. Next, only one of the three photoconductive layers is exposed to light having a substantial photosensitivity (all th) to form a potential pattern of a color separation image corresponding thereto, and this potential pattern is applied to the photoconductive layer of the photoconductive layer. Develop with toner of a color corresponding to each layer.

After making the photoreceptor potential uniform by recharging, a multicolor image consisting of superimposed color toner images is formed on the photoreceptor by repeating the entire surface exposure and development operations for each color separated image, and - times of transfer. A multicolor image is recorded on the transfer material all at once.

E, Example Hereinafter, the present invention will be specifically explained in terms of practicality.

In the following explanation, we will only discuss a photoreceptor for full color reproduction using each photoconductive layer as a photosensitive layer that is sensitive to only red, green, and blue light, but we will discuss the spectral sensitivity of each photoconductive layer and the combination thereof The color of the toner is not limited to this.

FIG. 1 schematically shows a cross section of a photoreceptor 1 according to the present invention. Insulating layer 11 on conductive substrate c, B
, a red photosensitive layer PR, a red photosensitive layer I, a green photosensitive layer PGS insulating layer I3, a blue photosensitive layer PB1 and a surface insulating layer I4 are arranged in an overlapping manner.

The photoreceptor 1 may be made of metals such as aluminum, iron, nickel, copper, or alloys thereof, and may have an appropriate shape and structure as necessary, such as a cylindrical shape or an endless belt shape.

Insulation*1. The insulating layer I can be composed of an insulating material, such as a vertebral polymer resin.

It is necessary to have translucency, and if necessary, a coloring agent such as a pigment or dye may be added to form a color filter. The thickness of one insulating layer is preferably about 5 to 50 μm.

The photosensitive layer PR5PGs P B is made of inorganic phototetraelectric substances such as oxides, iodides, sulfides, and selenides of metals such as zinc, aluminum, antimony, bismuth, cadmium, and molybdenum, vinylcarbazole, anthracenephthalocyanine, trinitrofluorenone, Organic photoconductive substances such as polyvinyl carbazole, polyvinylanthracene, and polyvinylpyrene are combined with insulating materials such as polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, acrylic resin, silicone resin, fluorine resin, and epoxy resin. It is composed of materials dispersed in a binder resin.

The spectral sensitivity of the photosensitive layer is determined as follows. In other words, the red photosensitive layer PR1, the green photosensitive layer Pa, and the evening photosensitive layer PB need to have photosensitivity to substantially only red light, green light, and blue light, respectively. Substantially having photosensitivity means not only the photosensitivity of the photosensitive layer, but also includes a color filter effect in which specific wavelength components are absorbed by the upper insulating layer and photosensitive layer. FIG. 2 shows the spectral sensitivities of the red photosensitive layer PR, the green photosensitive layer PG, and the blue photosensitive layer pB in this example. in this way,
Even if the photosensitive layers themselves do not have preferable photosensitive characteristics, if the spectral characteristics are designed in consideration of the color filter effect of the upper layer, each photosensitive layer can have substantially preferable spectral sensitivity.

For example, as shown in FIG. 3 (al), from above, the back light layer FB
, a green photosensitive layer PG, and a red photosensitive layer P. When the photosensitive layers are laminated in this order, a filter layer Fb that absorbs blue light is placed between the photosensitive layers PB and Pa, and a filter layer that absorbs green light is placed between the photosensitive layers PG and PR. If Ff is provided, each photosensitive layer will be
The photosensitive layers are laminated in the order of spectral input PB, PR, and PG as shown in the same figure (cl) or the same figure (dl), and the photosensitive layer FB
A filter layer Fb that absorbs blue light is provided between pR and PR, and a filter layer F that absorbs red light is provided between photosensitive layer pR and PG.
r, or as shown in the same figure (b), the photosensitive layers are laminated in the order of photosensitive layers PnsPB%PG from above, and a filter layer Fr that absorbs red light is formed between the photosensitive layers pR and pB.
In the case where a filter layer Fb that absorbs blue light is provided between the photosensitive layers FB and PG, each photosensitive layer may have a divided light sensitivity as shown in the same figure (cl).

Furthermore, in the configuration shown in FIG. 4(b), each photosensitive layer may have a spectral sensitivity as shown in FIG. 5.

Hereinafter, an example of producing a photoreceptor will be specifically described.

Prepare photosensitive liquids with spectral sensitivities for blue, green, and red, respectively.
These are mixed solutions consisting of zinc oxide, its sensitizing dye, a binder, and a solvent, as shown in Table 1 below.

Table 1 After adjusting the viscosity of the photosensitive liquid using a solvent, spherical particles having an average particle size of 30 to 300 μm were prepared by spray drying. Next, an adhesive layer of 0.1
It is coated to a thickness of about μm, and the prepared red-sensitive particles are sprinkled on it. Next, remove excess particles with air to form a monolayer. In this way, a fairly uniform monolayer of particles is formed. Next, the aluminum drum base and a metal roller in pressure contact with the aluminum drum base are rotated without being heated so that the particles adhere to the base and a smooth photosensitive layer with a thickness of 5 to 60 μm is provided.
After layering thick insulating and transparent shrink tubes,
Heat shrink. Thereafter, in a similar manner, a single layer of particles sensitive to green light, a transparent insulating layer, a single layer of particles sensitive to blue light, and a transparent insulating layer are provided to be superimposed on this.

Next, a multicolor image forming process using the photoreceptor of the present invention will be explained with reference to FIG.

First, when the entire surface is exposed to white light (arrow Lw) at the same time as a positive corona discharge is applied to the entire surface using the band device 4, a negative charge is generated on the surface of the photoreceptor 1 and a positive charge is generated on the side of the substrate C08. state.

Then, as shown in (In), alternating current or negative charge is applied by a charger 5 equipped with an exposure slit, and a colored image is exposed while erasing the charge on the surface of the human face insulating skin 4. In (II) N,WXC,M.

Y, RlGSB are image exposure black, white, cyan,
It shows magenta, yellow, red, younger sister, and blue parts.

A latent image corresponding to each color is formed in the surface insulating layer and the photosensitive layer as a pattern of charge density. The discharge by the charger 5 is preferably such as to smooth the optical surface potential of the photoreceptor.

Hereinafter, the state [11] will be referred to as primary latent image formation.

This is because the surface of the photoreceptor has the same potential, so it apparently does not function as an electrostatic latent image.

Then, as shown in [1], one of the photosensitive layers, for example, a red photosensitive layer, is exposed to red light (arrow LR) to which it is sensitive. As a result, charge movement occurs in the red photosensitive layer pR, and a red component potential pattern is generated on the surface of the photosensitive member.
As shown in Figure 2, when development is performed with cyan toner O, cyan toner 0 adheres only to the portions that were not hit by the red light LR during image exposure. Furthermore, in order to smooth the potential after development, as shown in
Discharge is performed by C.

Then, as shown in CM), the green light (arrow La)
When fi exposure is applied, a green component potential pattern is generated in the same manner as the red light, and as shown in (1), development is performed with magenta toner 〇, and as shown in (4), the potential of the photoreceptor is changed using a 15M machine. Make it uniform. As a result, a two-color image of cyan toner and magenta toner is formed on the photoreceptor.

Next, when the entire surface is exposed to blue light (arrow LB) as shown in Figure 0, a blue component potential pattern is generated, similar to the red light, and as shown in [X], it is developed with yellow toner ■. . As a result of the above steps, a color toner image is formed on the photoreceptor.

Note that the colors of the above toners are not the three primary colors of light but actual colors. (The same applies hereafter).

When the color toner image thus formed is transferred to a transfer material such as paper and fixed, an original image (original) is reproduced and recorded by the color mixture of each toner.

Note that the monochromatic light exposure and toner development are not necessarily performed in the above order; for example, as described later, blue light exposure, yellow toner development, green light exposure, magenta toner development, and red light exposure may be performed. , cyan toner development.

Further, although the above description is based on an example in which positive corona discharge is used for primary charging by charging electrode 4, negative corona discharge may also be used. In this case, the basic process is the same except that the signs of the charges are all reversed.

Incidentally, it is not necessary to irradiate the entire surface with the light used in conjunction with the negative charging.

As is clear from the above explanation, the main point of this example is that after image exposure, light with a specific spectral distribution is applied to a photoreceptor in which a plurality of photosensitive layers with different photosensitive characteristics are laminated with a transparent insulating layer in between. The method involves forming a latent image on one of a plurality of photosensitive layers by exposing the entire surface to light, and developing the image using toner of the corresponding color, one color at a time, to obtain a multicolor image.

FIG. 7 is a schematic diagram of an image forming section of a color copying machine suitable for carrying out the present invention.

In the figure, reference numeral 41 denotes a photosensitive drum consisting of a photosensitive member having the structure shown in FIG. 1, which rotates in the direction of arrow a during a copying operation.

As the photosensitive drum 41 rotates, it is irradiated with light as necessary, and the entire surface is charged with a charging electrode 4. The photosensitive drum 41 is then subjected to an alternating current or a corona discharge of the opposite sign to the electrode 4 from an electrode 5 having an exposure slit. Exposure of the original is applied and the primary latent image formation process is completed.

Next, the entire surface is exposed to blue light obtained by the combination of the light source 6B and the light source blue filter FB, and an image is formed by the developer 7Y loaded with yellow toner.

Furthermore, the surface potential is made uniform by charging 615Y.

Next, the entire surface is exposed to green light from the light source 6GS and the one-color light source filter FG, development is performed by the developing device 7M loaded with magenta toner, surface potential is smoothed by the Teishoku 15M, and red light is applied from the light source 6R, red light source filter 6R75), etc. A multicolor image is formed on the photosensitive drum through full-surface exposure and development by a developing device 7C loaded with cyan toner. The obtained multicolor toner image is transferred by a transfer electrode 9 onto a paper 8 fed by a paper feeding means (not shown). The sheet carrying the multicolor toner image to be transferred is separated from the photosensitive drum by a separation electrode and fixed by a theorem device (not shown) to form a completed multicolor copy, which is then discharged outside the machine. After the transfer, the photosensitive drum 41 is irradiated with static eliminating light as needed and is moved to the static eliminating electrode 11.
The charge is removed by the cleaning blade 12, and the toner remaining on the surface is removed by the cleaning blade 12, and the toner is used again.

The developer used in the present invention can be either a so-called one-component developer using a magnetic toner or a so-called two-component developer containing a mixture of toner and a magnetic carrier. For development, a method of directly rubbing with a magnetic brush may be used, but in order to avoid damage to the formed toner image, especially after the second development, a developing method in which the developer layer does not come into contact with the photoreceptor surface is used, for example, U.S. Pat. , 893,418 and Japanese Patent Application Laid-Open No. 18656/1989 are good examples, especially Japanese Patent Application No.
It is preferable to use the method described in the specifications of Japanese Patent Application No. 8-57446, Japanese Patent Application No. 8-238295, and Japanese Patent Application No. 58-238296. These particularly preferred methods use a two-component developer that can use non-magnetic toner with freely selectable coloring, and develop without contacting the developer layer with the electrostatic image support with an alternating electric field formed in the development area. This is what we do.

The color toner used for development is made using known techniques, including known binder resins, organic and inorganic pigments, dyes, and other chromatic and achromatic colorants and various magnetic weight additives, etc., which are commonly used in toners. Toner for developing electrostatic images made by the above can be used, and the carrier can be iron powder, ferrite powder, which are usually used for electrostatic images, those coated with resin, or those with magnetic material dispersed in resin. It is possible to use various known carriers such as magnetic carriers.

In addition, the applicant filed the patent application No. 58-24966 earlier.
The developing method described in the specification of No. 9, 240066 may be used.

Further details of the developer used in the present invention are as follows.

That is, Japanese Patent Application Nos. 58-57446, 58-96900, 5B-96901, and 5
No. 8-96902, No. 58-183152, No. 58-
No. 184381, No. 58-187000, No. 58-5
As stated in the '7446 specification, it is desirable that the carrier and toner meet the following conditions.

First, regarding the carrier, the fact that the magnetic carrier particles are spherical improves the agitation performance of the toner and carrier and the transportability of the developer, and also improves the charge controllability of the toner, allowing the toner particles to form a spherical shape. Toner particles and carrier particles are less likely to aggregate. However, in the present invention, if the average particle size of the magnetic carrier particles is large, (1) the ears of the magnetic brush formed on the developer transport carrier are rough, and the electrostatic image is developed while being vibrated by the electric field; Also, problems may occur, such as unevenness tends to appear in the toner image, and high density development cannot be performed because the toner density in the spikes becomes low. In order to solve this problem (2), the average particle size of the carrier particles can be reduced, and as a result of experiments, the effect begins to appear when the average particle size is 50 μm or less, and especially 30 μm.
It has been found that when the thickness is less than m, the problem (2) does not substantially occur. In addition, the problem @ is also solved by making the magnetic carrier finer particles, which increases the toner concentration in the spikes and enables high-density development. However, if the carrier particles are too fine, they may adhere to the surface of the image carrier together with the O toner particles, or they may easily scatter.

These phenomena depend on the strength of the magnetic field acting on the carrier particles,
This is also related to the strength of the magnetization of the carrier particles,
According to experiments, this tendency gradually begins to appear when the average particle size of the carrier particles is 15 μm or less, and becomes more pronounced when the average particle size is 5 μm or less. The carrier particles adhering to the surface of the image bearing member (photoreceptor) usually have a dark color, and some of them migrate onto the recording paper etc. together with the toner, thereby seriously affecting the color image.

For the above reasons, the average particle size of the magnetic carrier is 5.
The proper condition is 0 μm or less, particularly preferably 30 μm or less, 5 μm or more, and even more preferably 15 μm or more, and it is preferable that the particle size is spherical.

The above average particle diameter is based on the Cole Counter (manufactured by Cole Co., Ltd.)
This is the weight average particle diameter determined by

Such magnetic carrier particles may contain metals such as iron, chromium, nickel, and cobalt, or compounds or alloys thereof, such as triiron tetroxide and r-ferric oxide, as in conventional magnetic carrier particles. The particles of ferromagnetic or paramagnetic substances such as diiron, chromium dioxide, manganese oxide, ferrite, manganese-copper alloys are made fine, preferably spherical, or the surfaces of these magnetic particles are preferably made of styrene. resins, vinyl resins, ethyl resins, rosin modified resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, palmitic acid,
Cover it in a spherical shape with fatty acid wax such as stearic acid, or
Or, more preferably, particles of resin or fatty acid wax containing dispersed magnetic fine particles are pulverized or granulated and polymerized to preferably form spherical particles, and the obtained particles are used to obtain particles with a conventionally stated average particle size. It is obtained by sorting the particle size using a diameter-based means.

In addition to the above-mentioned effects, forming the carrier particles into a spherical shape using a resin or the like as described above makes the developer layer formed on the developer transport carrier uniform, and also makes the developer transport carrier highly spherical. It also has the effect of making it possible to apply a bias voltage.

That is, the fact that the carrier particles are made spherical by resin etc. is because (1) Generally, carrier particles tend to be magnetized and attracted in the long axis direction, but by making them spherical, this directionality is lost, and therefore the developer layer is uniform. (2) As the resistance of the carrier particles increases, the edge portions seen in conventional carrier particles disappear, and the edge portions As a result, even if a high bias voltage is applied to the developer transport carrier, the static electricity may disturb the latent image by discharging on the surface of the image carrier, or the bias voltage may break down. It gives the effect that what you want to do will not happen. Being able to apply this high bias voltage means that when development under an oscillating electric field in a preferred embodiment of the present invention is performed by applying an oscillating bias voltage, the effects described below can be fully exhibited. This means that it can be done. As mentioned above, wax can also be used as carrier particles that have the above-mentioned effects, but from the viewpoint of the durability of the carrier, it is preferable to use resin as mentioned above. It is preferable to form insulating magnetic particles so that the resistance is 10'Ω or more, particularly about 1g13Ω or more. This resistivity is calculated by placing the particles in a container with a 0.50 cm"
This value is obtained by applying a load (kg/cm"cl) and reading the current value when applying a voltage that generates an electric field of 100OV/cm between the load and the bottom electrode. If this resistivity is low, When a bias voltage is applied to the developer transport carrier, charge is injected into the carrier particles, making it easier for the carrier particles to adhere to the surface of the image carrier, or for bias voltage breakdown to occur more easily.

In summary, the magnetic carrier particles are spherical so that the ratio of the major axis to the minor axis is at least 3 times or less, have no protrusions such as needles or edges, and have a resistivity of 10. It is appropriate that the magnetic carrier particle has a resistance of at least 1013 Ωα, preferably at least 1013 Ωα. In the case of high-resistance spherical magnetic particles or resin-coated carriers, the magnetic particles should have a spherical shape as much as possible. For the carrier of magnetic fine particle dispersion system, use magnetic fine particles as much as possible, and perform spheroidization treatment after forming the dispersed resin particles, or use spray drying method. It is manufactured by obtaining dispersed resin particles, etc.

Next, regarding toner, as the average particle size of toner particles in a two-component developer becomes smaller, the amount of charge qualitatively decreases in proportion to the square of the particle size, and relatively The adhesion force increases, making it difficult for the toner particles to separate from the carrier particles, and once the toner particles adhere to the non-image area of the image carrier surface, they cannot be easily removed by rubbing with a conventional magnetic brush. This will cause a fog to form. In the conventional magnetic brush development method, such problems became noticeable when the average particle size of toner particles was 10 μm or less. The developing method of the present invention solves this problem by performing development using a developer layer, a so-called magnetic brush, under an oscillating electric field.

That is, the toner particles adhering to the developer layer are easily moved away from the developer layer and transferred to the image area and non-image area on the image carrier surface by the electrically applied vibrations, and are also easily separated from the developer layer. In addition, toner particles with a low charge amount hardly migrate to image areas or non-image areas, and since they are not rubbed against the surface of the image carrier, they do not adhere to the image carrier due to frictional charging. As a result, toner particles with a particle size of about 1 μm have come to be used. Therefore, it is possible to obtain a clear toner image with good reproducibility in which the electrostatic latent image is faithfully developed. Furthermore, since the oscillating electric field weakens the bond between toner particles and carrier particles, the adhesion of toner particles and accompanying carrier particles to the image bearing surface is also reduced.

In the image area and non-image area, toner particles with a large amount of charge vibrate under an oscillating electric field, and depending on the strength of the electric field, the carrier particles also vibrate, so that the toner particles selectively move to the image area on the image carrier surface. Because it will move to
Adhesion of carrier particles to the image carrier surface is significantly reduced.

On the other hand, as the average particle size of the toner increases, as described above, the roughness of the image becomes noticeable.

Usually, toner with an average particle size of about 20 μm is not a practical problem for developing fine lines lined up at a pitch of 10 lines/today with good resolution. However, if fine particles with an average particle size of 10 μm or less are used, The resolution has been significantly improved, and it is now possible to produce clear, high-quality images that faithfully reproduce the differences in shading. For the above reasons, the average particle size of toner is 2.
A suitable condition is 0 μm or less, preferably 10 μm or less. Furthermore, since the toner particles follow the electric field, the amount of charge on the toner particles is 1 to 3 μc/? It is desirable that it be larger (preferably 3 to 100 μC/2). Particularly when the particle size is small, a high band 14 meal is required. Further, the resistivity is preferably 10 8 Ωα or more, preferably 10 13 Ω or more.

Such toner can be obtained in the same manner as conventional toner. That is, it is possible to use a toner in which spherical or amorphous nonmagnetic or magnetic toner particles in conventional toners are sorted by an average particle size sorting means. Among these, it is preferable that the toner particles are magnetic particles containing magnetic particles, and in particular, the amount of magnetic fine particles is so
It is preferable that the amount does not exceed 30 wt%, but in order to obtain color clarity, a small amount of 30 wt% or less is preferable. When the toner particles contain magnetic particles, the toner particles are influenced by the magnetic force of the magnet included in the developer transport carrier, so that the uniform formation of the magnetic brush is further improved. The occurrence of fogging is prevented, and furthermore, scattering of toner particles becomes less likely to occur.

However, if the amount of magnetic material contained is too large, the magnetic force between the carrier particles and the carrier particles becomes too large, making it impossible to obtain a sufficient developing density. Friction M
11ttIIIJ becomes difficult to control, the toner envelope becomes easily damaged, and the toner particles become agglomerated with the carrier particles.

Considering the above, the preferred toner in the image forming method of the present invention uses a resin as described above for the carrier and further fine particles of magnetic material, and a coloring component such as carbon and a charge control agent, etc., as necessary. In addition, the toner particles are made of particles having an average particle diameter of less than 1 μm, particularly preferably less than 10 μm, which can be produced by a method similar to the conventional method for producing toner particles.

In the image forming method of the present invention, a developer in which the above-described spherical carrier particles and toner particles are mixed in the same proportion as in a conventional two-component developer is preferably used; If necessary, a fluidizing agent to improve the fluidity and sliding of the particles, a cleaning agent to help clean the surface of the image carrier, and the like are mixed. As a fluidizing agent, colloidal silica, silicon face, metal soap, or a nonionic surfactant can be used, and as a cleaning agent, a fatty acid metal salt, organic group-substituted silicon, or a surfactant such as fluorine can be used. I can do it.

The above are the conditions for the developer, and next, the conditions for the developer transport carrier that forms a developer layer with such a diameter developer and develops the electrostatic image on the image carrier will be described.

A developer transport carrier similar to that used in conventional development methods to which a bias voltage can be applied is used as the developer transport carrier, but in particular, a developer transport carrier having a plurality of magnetic poles inside a sleeve on which a developer layer is formed on the surface. A structure in which a rotating magnet is provided is preferably used. In such a developer transport carrier, the rotation of the rotating magnet causes the developer layer formed on the surface of the sleeve to move in an undulating manner, so that new developer is successively supplied and the sleeve Even if there is some unevenness in the thickness of the developer layer on the surface,
This effect is sufficiently covered by the above-mentioned wave-like undulations so that it does not become a problem in practice.

Therefore, it is preferable that the conveying speed of the developer due to the rotation of the rotating magnet or the rotation of the sleeve is almost the same as or faster than the moving speed of the image carrier. Also,
The conveyance direction due to the rotation of the rotating magnet and the rotation of the sleeve is
The same direction is preferred.

Image reproducibility is better in the same direction than in the opposite direction. However, it is not limited to these.

In addition, the thickness of the developer layer formed on the developer transport carrier is
It is preferable that the thickness is such that the adhered developer is sufficiently scraped off by the thickness regulating blade to form a uniform layer.
The gap between the developer transport carrier and the image carrier is several tens to
2000 μm is preferred.

The surface gap between the developer transport carrier and the image carrier is several tens of meters.
If the width is too narrow, it will be difficult to form a magnetic brush that will uniformly develop the area, and
It becomes impossible to supply sufficient toner particles to the developing section, and stable development cannot be performed.
When it greatly exceeds 0 μm, the counter electrode effect decreases, making it impossible to obtain a sufficient developing density, and the edge effect, in which more toner adheres to the contours than the center of the electrostatic image, increases. . In this way, when the gap between the developer transport carrier and the image carrier becomes extreme, it becomes impossible to make the thickness of the developer layer on the developer transport carrier appropriate. Within this range, the developer layer can be formed with an appropriate thickness. Therefore, the gap and the thickness of the developer layer are adjusted such that the tip of the magnetic brush does not come into contact with the surface of the image carrier with a gap of 10 to 500 μm under conditions where no oscillating electric field is applied.
It is particularly preferable to set the conditions so that they are close to each other. This is because the toner development of the latent image is prevented from having scratches or fog caused by the rubbing of the magnetic brush.

Further, development under an oscillating electric field is preferably carried out by applying an oscillating bias voltage to the sleeve of the developer transport carrier. Further, it is preferable to use a bias voltage that is a combination of a direct current voltage that prevents toner particles from adhering to non-image areas and an alternating current voltage that makes it easier for the toner particles to separate from the carrier particles. However, the present invention is not limited to the method of applying an oscillating voltage to the sleeve or the method of applying a superimposed voltage of DC and AC.

The developing method of the present invention as described above is shown in FIG.
This is implemented by an apparatus such as that illustrated in FIG.

8 to 10, reference numeral 41 denotes a drum-shaped image carrier made of the photoreceptor shown in FIG. 1, which rotates in the direction of the arrow and has an electrostatic image formed on its surface by a charging exposure device (not shown). , 22 is a sleeve made of a non-magnetic material such as aluminum, and 23 is a magnet provided inside the sleeve 22 and having a plurality of N and S magnetic poles on its surface in the circumferential direction. It constitutes a drug-transporting carrier. The sleeve 22 can rotate relative to the magnet body 23, and the figure shows a case where the sleeve 22 rotates in the direction of the arrow. Further, the N1S magnetic pole of the magnet body 23 is normally magnetized to a magnetic flux density of 500 to 1500 Cous, and its magnetic force forms a developer layer, ie, a magnetic brush, as described above on the surface of the sleeve 22.

24 is a regulating blade made of magnetic or non-magnetic material that regulates the height and amount of the magnetic brush, and 25 is a cleaning blade that removes the magnetic brush that has passed through the developing area A from the sleeve 22J. The surface of the sleeve 22 is the developer reservoir 2
6 comes into contact with the developer reservoir, thereby supplying the developer reservoir, and 27 is the developer reservoir 26.
This is a stirring screw that stirs the developer mixture to make the components uniform. When the developer reservoir 26 is developed, the toner particles therein are consumed.
8 is a toner hopper for replenishing the toner particles T as described above, and 29 is a supply roller having a concave portion on its surface for dropping the toner particles T into the developer reservoir 26. 30 is a bias power supply that applies a bias voltage to the sleeve 22 via the protective resistor 31.

The difference between the devices shown in FIGS. 8 to 10 is that in the device shown in FIG. 8, the sleeve 22 rotates in the direction of the arrow;
The magnet body 23 rotates in the direction of the arrow opposite to that of the magnet body 200.
r, p, m ~2000 r, p, m are preferred.
While the magnetic flux densities of the N and S magnetic poles are approximately equal, in the device shown in FIG. 9, the sleeve 22 rotates in the direction of the arrow, but the magnet body 23 is fixed, and the device shown in FIG. In this case, the magnetic flux densities of the N and S magnetic poles of the fixed magnet body 23 are not the same, and the magnetic flux density of the N magnetic pole facing the image carrier 41 is higher than the magnetic flux density of the other N and S magnetic poles. be. As for the poles facing the image carrier 41, it goes without saying that N magnetic poles may be arranged side by side and facing each other as shown in Figure 1O, or N and S magnetic poles may be arranged side by side and opposed to each other. By arranging a plurality of magnetic poles to face each other in this manner, it is possible to obtain the effect that development is more stable than when a single pole is posed to face each other.

In the above-described apparatus, the sleeve 22 is attached to the image carrier 4.
When the electrostatic image on the image carrier 41 is developed by setting the surface gap to be in the range of several lO to 2000 μm, the magnetic brush formed on the surface of the sleeve 22 or As the magnetic flux density on the surface changes as the magnet 3 rotates, it moves on the sleeve 22 while vibrating, thereby stably and smoothly passing through the gap with the image carrier 41. At this time, a uniform development effect is imparted to the surface of the image carrier 41, making it possible to stably develop with a high toner density. For that,
In order to prevent the occurrence of fogging and to improve the developing effect, an image carrier 41 is connected to the sleeve 22 to which a bias voltage having an oscillating alternating current component is grounded by a bias power supply 30.
The voltage is applied between the base body 41a and the base body 41a.

As mentioned earlier, a preferable superimposed voltage of one DC voltage and an AC voltage is used for this bias voltage, and i[ME
The acid component prevents fogging, and the AC component gives vibration to the magnetic brush to improve the developing effect.

Note that the DC voltage component usually has a voltage approximately equal to the non-moving part potential, or
A higher voltage of 50 to 600 V is used, and the AC voltage component is 100 Hz to 1 O-1, preferably 1 to 5 K.
A frequency of H2 is used. Note that the DC voltage component is
If the toner particles contain a magnetic material, the potential may be lower than the non-partial potential. However, in order to maintain the clarity of colors, it is better to use less magnetic material. If the frequency of the variable current voltage component is too low, the effect of imaging cannot be obtained, and if it is too high, the developer will not be able to follow the imaging of the electric field, resulting in a decrease in development density and a clear, high-quality image. There appears to be a tendency for them to become unobtainable. In addition, the positive value of the AC voltage component is
The frequency is also related, and the higher the frequency, the more the magnetic brush will vibrate, which will increase the effect accordingly, but on the other hand, the higher the frequency, the more likely fog will occur and dielectric breakdown, such as that caused by lightning strikes, will occur more easily. However, the fact that the carrier particles in the developer are made spherical by resin or the like prevents dielectric breakdown, and the occurrence of fog can also be prevented by using the DC voltage component. Note that the surface of the sleeve 2 to which this AC voltage is applied may be coated with an insulating or semi-insulating coating with a resin or an oxide film.

As described above, FIGS. 8 to 10 show an example in which an oscillating bias voltage is applied to the developer transport carrier, but the developing method of the present invention is not limited to this. It is also possible to improve the developing effect by applying vibration to the magnetic brush by placing several electrode wires around the developing area and applying an oscillating voltage to them. In that case as well, a direct current bias voltage may be applied to the developer transport carrier, or imaging voltages of different frequencies may be applied.

In the developing device shown in FIGS. 8 to 10, the cleaning blade 25 may be installed near the screw 27, as shown by the imaginary line.

An example of specific conditions for forming a multicolor image using the multicolor image recording apparatus having the structure shown in FIG. 7, which incorporates the photoreceptor configured as shown in FIG. 1 and the developing device shown in FIG. The following are listed below.

Photoreceptor Diameter 1201111 Each layer thickness I, 0.1 μm PR204 ■, 10, a1 @ Po 20 /”m ■, 10 μ pB 20 p Funeral 1 1a 10 7u1η Surface potential Immediately after -order charging Immediately after simultaneous charging with earth and stone α image exposure -50V Immediately after full blue exposure +700V - Immediately after OV potential smoothing -50V Immediately after green full exposure +650V - Immediately after OV potential smoothing -50V Immediately after red full exposure +600V""'ov Each developing device sleeve diameter 20111 + number of magnetic poles
6 Sleeve surface magnetic flux density 800 Gauss Between photoconductor and sleeve 160M (Sleeve is non-magnetic stainless steel) Electrode The slit electrode is a scorotron, the others are corotron lamps, 6B, 6G, and 6R are halogen lamps,
Others are regulated by fluorescent lighting) Developing bias 7Y DC + 100V AC 1,5 base 0 failure) 2K
Hz7M [)C+ 50V AC1,2KV@i
! Effect 2KE (Z7CDC, +30V ACl, 2
KW! The color images obtained under conditions of m1m2KH2 or higher were clear and no color shift was observed.

As described above, according to the method of the present invention, it is possible to quickly and easily produce a multicolor image without color shift by performing imagewise exposures twice.

All of the above explanations have been made regarding actual examples of color copying machines that use photoreceptors sensitive to three colors and toners of three primary colors, but embodiments of the present invention are not limited to this, and two-color and other It can be widely used in various multicolor image recording devices, color photo printers, etc. It goes without saying that the combination of the color of the separation filter and the color of the toner corresponding thereto can be arbitrarily selected depending on the purpose.

Effects of the Invention As explained in detail above, the multicolor image forming method based on the present invention has the above-described configuration, so that the entire surface charging and image exposure, which conventionally required multiple times, can be performed only once. There is no need to align various images during transfer, and it is possible to make the multicolor electrophotographic apparatus more compact, faster, and more reliable. The resulting recorded matter will also be of high quality with no color shift.

[Brief explanation of drawings]

The drawings all show examples of the present invention, and FIG. 1 is a cross-sectional view schematically showing the structure of a photoreceptor, FIG. 2 is a graph showing the spectral sensitivity of the photosensitive layer, and FIG. 4 and 5 show the relationship between the structure of a photoreceptor and the spectral sensitivity of a photosensitive layer that is compatible with the structure, and FIG. , (C1 and (dl) are graphs showing the spectral sensitivity of the photosensitive layer, Figures 4 (a) and (b) are cross-sectional views schematically showing other examples of photoreceptors, and (cl is the graph showing the spectral sensitivity of the photosensitive layer). Graph showing the sensitivity, Figure 5 is a graph showing the spectral sensitivity of other photosensitive layers, Figure 6 is a flowchart showing the process of forming a multicolor image, and Figure 7 shows the main parts of the multicolor image forming apparatus. The schematic diagrams shown, FIG. 8, FIG. 9, and FIG. 10 are all cross-sectional views of the developing device used in the multicolor image forming apparatus. ......Photoreceptor 41...Photoreceptor drum 4...Charging electrode 5...Electrode 7Y, 7M, 7C...Developer 8...
...... Transfer electrode 11... Static elimination electrode 22... Toner transport sleeve 23...
...... Magnet body 24 ...... Toner regulation blade 25 ...
......Bias power supply C, B, ...Base L, I3, I4...Insulating layer PR...
...... Red photosensitive layer PG... Green photosensitive layer FB... Blue photosensitive layer Lw """"' White light Lm... ...Red light... Green light LB... Blue light. Agent Patent Attorney Hironaga Aisaka (nm) Fig. 3 UJlfi (nm) (C) (d) ρq Fig. 4 (a) (b) Kumicho (nm)
) Figure 8 Figure 9

Claims (1)

[Claims] 1. A photosensitive layer P_1 having substantially no sensitivity in f_2 and substantially having sensitivity in f_1 in the visible light range consisting of at least wavelength ranges f_1 and f_2; A photosensitive layer P_2 substantially having sensitivity is laminated with an insulating layer interposed therebetween, a conductive substrate is placed on the photosensitive layer P_2 side, and a photosensitive layer P_2 is layered on the photosensitive layer P_2 side.
While discharging a photoreceptor having an insulating layer on one side, the photoreceptor layer P
After imagewise exposure is applied from the _1 side; the entire surface of the photoreceptor is exposed to light that makes substantially only one of the photosensitive layers conductive, and the photoreceptor is developed with a toner of a color corresponding to the one layer of the photosensitive layer. A multicolor image forming method that repeats the process of 2. Of the visible light range consisting of wavelength ranges f_1, f_1, and f_2, it has virtually no sensitivity in f_2 and f_3;
A photosensitive layer P_1 having a sensitivity substantially at f_1; a photosensitive layer P_3 having substantially no sensitivity at f_2 and a substantially sensitivity at f_3; a photosensitive layer P_3 having a sensitivity substantially at f_2; layer P_2 are laminated with an insulating layer interposed therebetween, a conductive substrate is provided on the photosensitive layer P_2 side, and an insulating layer is provided on the photosensitive layer P_1 side, and image exposure is applied from the photosensitive layer P_1 side while discharging. After that, the process of exposing the entire surface of the photoreceptor to light that makes substantially only one layer of the photoreceptor conductive, and developing the photoreceptor with a toner of a color corresponding to the one layer of the photoreceptor layer is repeated. The multicolor image forming method according to item 1.