JPH02287368A - Image forming method using photosensitive toner - Google Patents

Abstract

PURPOSE:To avert color mixing by irradiating a toner layer at a high intensity with light with which any of photosensitive toners has sensitivity and irradiating the layer at a low intensity with light with which the toners of the other colors have sensitivity. CONSTITUTION:Composite light, such as white light, is used for the light to be projected from a light source 23. The chromatic light rays corresponding to the respective colors of an original 22 are projected to the toner layer. The intensity of the light is set at such intensity at which the charge erasing of the photosensitive toners 15 of the respective colors is effectively executed. Further, a light source 24 for color sepn. is provided and the light thereof is projected directly to the toner layer. The projected light is kept within the range of 1 to 50% of the light projected from the light source 23. The charge erasing of the photosensitive toners of the colors corresponding to the image originals is executed in this way and since the electrostatic force of the other photosensitive toners is weakened, the photosensitive toners of the colors corresponding to the original images is completely scraped off by a magnetic brush 17. The effective color sepn. is executed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming method for forming a color image using a photosensitive toner by a so-called voltage application simultaneous exposure and simultaneous transfer method.

(Prior art and its problems) Conventionally, a color image is formed by using three color photosensitive toners and applying a voltage application, simultaneous exposure and simultaneous transfer method, and exposing each toner image to light to which it is sensitive. This is publicly known.

In this color image forming method, bias development is performed using three color toners mixed in advance to form a toner layer on a transparent conductive substrate, and at the same time image exposure is performed.

That is, the three-color toner consists of cyan toner, magenta toner, and yellow toner, and the cyan toner is sensitive to red light, the magenta toner is sensitive to green light, and the yellow toner is sensitive to blue light.

Therefore, when the exposure light is red light, only the cyan toner has photosensitivity, so only the charge of this toner is erased and scraped off by the magnetic brush.

As a result, magenta toner and yellow toner are developed to obtain a red image.

However, in such a color image forming method,
A fatal drawback associated with the simultaneous development of three color toners is that color separation is not performed effectively and the degree of color mixing is significant.

(Means for Solving the Problems) An object of the present invention is to provide a method for effectively separating colors and preventing color mixing in a color image forming method using a voltage application, simultaneous exposure, and simultaneous transfer system. .

That is, according to the present invention, in the image forming method in which a toner layer consisting of photosensitive toners of at least two colors is formed on a transparent conductive substrate and at the same time imagewise exposure is performed to form a color image, the imagewise exposure comprises: This is carried out by irradiating the toner layer with light to which one of the photosensitive toners is sensitive at a sufficient light intensity, and at the same time, during image exposure, the light to which the photosensitive toner of the other color is sensitive is irradiated to the toner layer at a low light intensity. An image forming method is provided, which comprises irradiating the image.

(Function) In FIG. 1, which simply shows the principle of the present invention, a toner layer 2 is formed on a transparent four-electroconductive substrate 1. As shown in FIG.

When image exposure is performed in this state, the charge on the toner 2a having sufficient photosensitivity to the exposure wavelength disappears, and the charge on the toner 2b not having photosensitivity to the exposure wavelength remains as it is.

Therefore, the toner 2a is scraped off by the magnetic brush, and only the toner 2b remains for development.

Silently, add toner 2 as shown in Figure 1.
If the toner 2b is placed on top of a, even if the charge on the toner 2a disappears, the toner 2a is pressed down from above by the toner 2b, so the toner 2a cannot be scraped off effectively. This results in color mixture.

According to the present invention, image exposure is performed by irradiating light to which the toner 2a is sensitive at a sufficient light intensity, and at the same time, light to which the toner 2b is sensitive is irradiated at a low light intensity.

That is, due to such low-intensity light irradiation, an electrostatic force acts on the toner 2b, in other words, the toner 2b in FIG.
The force of pressing is weakened, and the magnetic brush removes the toner 2.
b is moved, making it possible to effectively scrape off the toner 2a underneath.

Thus, in the present invention, color mixing can be effectively avoided.

(Preferred Embodiment of the Invention) In FIG. 2 showing an example of an apparatus for suitably carrying out the method of the present invention, this apparatus includes a toner layer supporting electrode 10, which is a rotating cylinder, and a toner layer supporting electrode 10 separated from the electrode 1o by a predetermined distance. It consists of a transparent conductive substrate 11.

The toner layer supporting electrode 10 is made up of a conductive sleeve 12 and has a magnet 13 therein.

In this apparatus, photosensitive toner 15 of at least two colors is used.
is used in the form of a mixture with a magnetic carrier 16 to form a magnetic brush 17 on the sleeve 12, which magnetic brush 1
7 is supplied so as to rub against the transparent conductive substrate 11.

In this case, the toner layer supporting electrode 1o and the transparent conductive substrate 11
For example, in FIG. 2, a bias voltage is applied between the supporting electrode 1o and the conductive substrate 11.
has Φ polarity, and the photosensitive toner 15 is charged with e polarity due to frictional charging, and the conductive substrate 11 is charged due to electrostatic attraction.
A toner layer is formed on top.

On the other hand, a document placement table 21 is located at a position separate from the conductive substrate 11.
is provided, and a document 22 is placed thereon.

That is, the RGI 22 is irradiated with light from the image exposure light source 23, and this reflected light passes through the transparent conductive substrate 11 and is irradiated onto the toner layer, thereby performing image exposure.

However, in the present invention, since color development is performed, composite light such as white light is used as the light emitted from the light source 23, and colored light corresponding to each color of the original 'FF422 is irradiated onto the toner layer. be done.

The intensity of the light emitted from the light source 23 is set to be sufficient to effectively erase the charges of the photosensitive toner 15 of each color.

Further, according to the present invention, a light source 24 for color separation is provided, and composite light such as white light is directly irradiated onto the toner layer from the light source 24 without passing through the original 22.

The light intensity of the light emitted from the light source 24 must be in the range of 1 to 50% of that of the light emitted from the light source 23. That is, if the light intensity is greater than this range, not only the charge of the color corresponding to the original image but also the photosensitive toner of other colors will be erased. If it is small, the electrostatic force of photosensitive toner of colors other than the color corresponding to the original image cannot be weakened, making it difficult to perform color separation effectively.

In order to obtain light having the above-mentioned light intensity, for example, the amount of light itself may be reduced or an appropriate filter may be used. Of course, by using the same light source as the light sources 23 and 24 and using appropriate lenses, prisms, etc., one light source is
Alternatively, the toner layer may be irradiated with the other light through a filter or the like.

Further, the light from the light sources 23 and 24 described above is not limited to white light, but may be composite light consisting of colored light corresponding to the color of each photosensitive toner.

Thus, according to the present invention, the charge of the photosensitive toner of the color corresponding to the original image is erased by image exposure, and the electrostatic force of other photosensitive toners is weakened, so that the photosensitive toner of the color corresponding to the original image is erased. is completely scraped off by the magnetic brush 17, and the photosensitive toner is transferred onto the transparent conductive substrate 11.

The photosensitive toner of each color used in the present invention includes a photoconductive pigment such as an inorganic photoconductor such as zinc oxide or Cds, a perylene pigment, or a perylene pigment in an electrically insulating resin fixing medium.
Particles made of a composition in which a photoconductive organic pigment such as a quinacridone pigment, a vilanthrone pigment, a phthalocyanine pigment, a disazo pigment, or a trisazo pigment is dispersed are used. Photoconductive pigment is a fixing medium 100! 3 per part
From 5 to 600 parts by weight, especially from 5 to 500! It is best to use quantitative parts. When the amount of photoconductive pigment is less than the above range, image density and toner sensitivity tend to decrease;
Moreover, when the amount exceeds the above range, charge retention characteristics tend to deteriorate.

As the fixing medium, electrically insulating fixing resins known per se, such as polystyrene, styrene-acrylic copolymer, acrylic resin, polycarbonate, polyarylate (polyester of bisphenol A and iso- or terephthalic acid), polyvinyl butyral, Polysulfone can be used, and photoconductive resins such as polyvinylcarbazole, alone or in combination with electrically insulating resins, are also useful for the purposes of this invention.

In a preferred photosensitive toner, a charge transport medium is used as a fixing medium, and the above-mentioned photoconductive pigment is dispersed in the charge transport medium as a charge generating pigment, and this dispersion is used as a photoconductive toner.

As the charge transport medium, the above-mentioned electrically insulating resin and charge transport substance such as polyvinylcarbazole, phenanthrene, N-ethylcarbazole, 2,5-diphenyl-
1,3,4-oxadiazole, 2,5-bis-(4-
diethylaminophenyl)-1,3,4-oxadiazole, bis-diethylaminophenyl-1,3-8-oxadiazole, 4.4″-bis(diethylamino)-
2,2°-dimethyltriphenylmethane, 2°4.5-
1-riaminophenylimidazole, 25-bis(4-
diethylaminophenyl)-1゜3.4-)-riazole, 1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl)-2-pyrazoline, p-diethylaminobenzaldehyde-(diphenylhydrazone) Hole transport materials such as 2-nitro-
9-fluorenone, 2,7-sinitro-9-fluorenone, 2,4.7-tronitro-9-fluorenone, 2,
At least 1f of electron transport substances such as 4,5,7-titranitro-9-fluorenone, 2-nitrobenzothiophene, 2,4°8-trinidrothioxanthone, dinitroanthracene, dinitroacridine, dinitroanthraquinone! combinations are used. The charge transport material is −
Numerically speaking, it is preferable to use an amount of 1 to 200 parts by weight, especially 30 to 120 parts by weight per 100 parts by weight of resin.

In addition to the above-mentioned essential components, auxiliary agents known per se can be added to the photosensitive toners of each color used in the present invention according to known formulations. Examples of such auxiliary agents include anti-offset agents such as waxes and agents for imparting pressure fixability.

Forming into a toner can be carried out by a dry method by mixing, crushing, and sieving, or by a wet method by spray granulation in the form of a dispersion, and the particle size of the toner particles is generally in the range of 5 to 30 microns. This is desirable.

The above-mentioned photosensitive toner has a negative triboelectric charging property, but a photosensitive toner having a positive tribocharging property may be made of a polyamide resin or the like instead of the above-mentioned fixing resin. A resin containing nitrogen atoms in the main chain or in the side chain may be used. When using a toner having such a positive triboelectric charging characteristic, the direction of the polarity of the bias power source 20 is reversed in FIG. 2.

In the present invention, a mixture of at least two of the above-mentioned photosensitive toners is used, and for -m, a mixture of three colors, cyan toner, magenta toner, and yellow toner, is used.

Further, as the magnetic carrier 16 used to form a magnetic brush that supplies and scrapes off the photosensitive toner onto the transparent conductive substrate, it is preferable to use iron powder, ferrite, or the like with a particle size of 30 to 100 μm. The mixing ratio of carrier and toner is 97:3 to 85:1 by weight.
It is better to be within the range of 5. The length of the magnetic brush varies slightly depending on other conditions, but generally it is 0.3 to 1 m.
A range of m is appropriate.

The color image formed on the transparent conductive substrate is electrostatically transferred onto a transfer paper or the like by means known per se and fixed to form a copy.

(Effects of the Invention) According to the present invention, it has become possible to form a color image without color mixture by the simultaneous exposure and transfer method when voltage application is opened.

(Example) In order to form a color image using the apparatus shown in FIG. A magenta photosensitive toner and a cyan photosensitive toner having photosensitivity around 650 nm are mixed in equal amounts. Further, a magnetic carrier 16 is contained in a mixing ratio of 5 parts by weight to 95 parts by weight of the photoconductive toner to frictionally charge the photoconductive toner to a negative charge, thereby forming a magnetic brush 17 on the conductive sleeve 12. .

A bias voltage of -200 V is applied to the conductive sleeve 12 to form a toner layer on the Nesa glass 11.

On the other hand, a document placement table 21 is located at a separate position from the Nesa glass 11.
is provided, and a document 22 is placed thereon.

Next, a halogen lamp with emission characteristics having uniform light intensity over a wavelength range of 400 nm to 700 nm is used as the light source 2 for image exposure.
3, the document 22 is irradiated with light from the image exposure light source 23, and this reflected light is transmitted through the Nesa glass 11 and irradiated onto the toner layer, thereby performing image exposure. At the same time, a halogen lamp having a light intensity of 5% of that of the image exposure light source 23 is used as a color separation light source 24, and light is directly irradiated onto the toner layer from the light source 24 without passing through the original 22.

The transfer process is not shown in the figure, but a transfer paper is placed on the toner layer after the light irradiation, and a positive charge is applied from the back side of the transfer paper to transfer the charged toner, The transfer paper then passes through a heated roller and is fixed. When an image was formed using the above-mentioned apparatus, an image with good color reproducibility without color mixture and close to the color of the original was obtained.

As a comparative example, when an image was formed without using the color separation light source 24, only an image with poor color reproducibility was obtained due to severe color mixing and a blackish appearance as a whole.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, and FIG. 2 is a diagram schematically showing the main parts of an apparatus for suitably carrying out the method of the present invention.

Claims (1)

[Scope of Claims] (I) An image forming method in which a toner layer consisting of photosensitive toners of at least two colors is formed on a transparent conductive substrate and at the same time imagewise exposure is performed to form a color image, comprising: This is carried out by irradiating light to which one of the photosensitive toners is sensitive at a sufficient light intensity, and at the same time, during image exposure, the toner is irradiated with light to which the other color photosensitive toner is sensitive at a low light intensity. An image forming method characterized by irradiating a layer.