JPH04278967A - Method for forming color image - Google Patents

Abstract

PURPOSE:To offer a color image having the same tone as a silver-salt photograph and depth by using an electrophotographic method. CONSTITUTION:A toner image is superposed and formed on a photosensitive body 40 by developing devices 46Y, 46M, 46C and 46BK and a transparent toner grain layer is formed on it by a developing device 46W. Thereafter, it is transferred on a transfer paper PA having a white surface part by the action of a transfer pole 47. Then, the transparent toner grain layer is attached on the substrate of the paper PA having the white surface part and a color toner image is attached on it. Besides, it is fixed by a fixing device 55 after it is transferred and separated by actuating the pole 47 and a separation pole 48. Then, the color image having a transparent substrate layer 7 is formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming method, and more particularly to a color image forming method capable of producing images with excellent color tone and depth.

0002

[Prior Art] Conventionally, in order to form a color image by electrophotography, a photoreceptor using an inorganic photoconductive material such as ZnO, Cds, Se, amorphous silicon, etc. or a phthalocyanine pigment, a bisazo pigment, a polycyclic quinone pigment, etc. is used. For example, an original is placed on a photoreceptor using an organic photoconductive material of color C.
A CD is read, image processed, color-corrected image data for each color is generated, and a laser beam modulated by the image data is irradiated to form an electrostatic latent image for each color.
Developed with different color toners (yellow), M (magenta), C (cyan), and BK (black), and each time a color toner image is formed, it is transferred to a transfer material, etc., and a color toner image is formed on the transfer material. There is a method of forming a color image and fixing it by heating or the like to form a color image.

[0003] Also, color toner images are superimposed on a photoreceptor to form a color toner image, and this is transferred/transferred all at once onto a transfer material.
There is also a method of fixing to form a color image.

By the way, all of the above-mentioned color toners contain pigments as a coloring agent dispersed in a binder resin.
The color toner image is composed of particles with a diameter of 0 μm, and the color toner image is usually formed with at least a portion of each color toner particle overlapping each other, and at least a portion of the color toner particles are heated and melted and fused to the transfer material and fixed. .

The coloring agents include Y coloring agents: benzidine yellow, quinoline yellow, Hansa yellow M coloring agents: rhodamine B, rose bengal, pigment red C coloring agents: phthalocyanine blue, aniline blue, pigment blue BK coloring agents: Carbon black, aniline black, furnace black, blends of color toners, etc. are used.

[0006]

[Problems to be Solved by the Invention] However, the aforementioned color toners have poor light transmittance as colorants, and the shape of toner particles remains even after fixing, so that the resulting color image is not irradiated with light. Most of the light reflected from the color layer is diffusely reflected on the surface, and there is little reflected light from within the color layer, so the image lacks depth, has poor color tone reproducibility, and is observed as a flat image.

FIG. 10 shows the state of reflected light when illumination light is irradiated onto a color image after conventional fixation. 1 shows a transfer material such as paper, 2 shows a color image, and 2C shows a color image. C
(cyan) toner image layer, 2M is M (magenta) toner image layer, and 2Y is Y (yellow) toner image layer. Illumination light 3 is diffusely reflected by the uppermost Y toner image layer as diffusely reflected light 4 and 3D, but some of the light penetrates into the layer and is absorbed by each layer of 2Y, 2M, and 2C, and 3Y, 3
M and 3C are reflected, and a color image is observed by the naked eye 5 from these reflected lights. In this case, only the light reflected from the surface of the toner layer is strong and the light reflected from within the toner layer is weak, resulting in an image with poor color tone and a flat image with no depth.

Therefore, for example, Y, M, C, which has excellent translucency,
When compared with silver salt color photographs, sublimation type thermal transfer copies, etc., which consist of a fine particle dye layer, the image depth and color tone are significantly inferior.

From this point of view, Japanese Patent Application Laid-Open No. 63-92964, 6
Japanese Patent No. 3-92965 proposes a color image forming method using, as a transfer material, a transfer material in which a transparent resin layer is coated in advance on a substrate having a white background.

An object of the present invention is to use electrophotography to provide a color image having a color tone similar to that of a silver halide photograph and having depth.

[0011]

[Means for Solving the Problems] The object is to provide a color image which includes a step of transferring a toner image formed on an image forming member onto a transfer material and a step of heating and fixing the toner image transferred onto the transfer material. A color image forming method, characterized in that the same effect can be obtained without using a transfer material in which a transparent base layer is provided on a substrate as the transfer material;
That is, in a color image forming method that includes a step of transferring and fixing a toner image on an image forming body to a transfer material, a step of attaching a transparent toner particle layer to the transfer material and fixing it on a substrate having a white background area as the transfer material. This is achieved by a color image forming method characterized by having the following.

[0012] As a preferred embodiment of the present invention,
A transparent toner particle layer is formed in addition to the toner image on the image forming body, and the toner image and the transparent toner particle layer are transferred and fixed onto a transfer material to form a color image having a transparent coating layer. ing.

Further, a transparent toner particle layer is formed on the transfer material by direct non-contact development, and the toner image formed on the image forming body is transferred, so that the toner image and the transparent toner particle layer are formed on the transfer material. A method of forming a toner particle layer and then fixing it to form a color image having a transparent coating layer is also a preferred embodiment of the present invention.

That is, in the image forming method of the present invention, when a toner image on an image forming body formed by electrophotography is transferred to a transfer material and melted and fixed by heating or the like to form a color image, the conventional transfer method is used. By providing a transparent toner particle layer and a color toner image using a material and fixing them to form a color image, the reflected light from each color layer constituting the color image layer is enriched and depth is given to the image. There are characteristics.

[0015] The present invention also has the effect of preventing diffused reflection on transparent substrates such as OHPs, and provides a desirable effect.

The transfer material used in the present invention is as shown in FIGS. 1 and 2, and the material 1a of the transfer paper 1 includes a paper sheet of wood pulp fiber, processed paper, synthetic paper, plastic sheet, metal sheet, etc. Although any of the above may be used, a paper sheet made of the above-mentioned pulp fibers is usually used. In order to form a white reflective surface 6, which is a white background part, on the material 1a made of a paper sheet, CaO, BaO, SrO, ZnO2, TiO2,
It may be formed by incorporating a white pigment such as BaSO4 into a paper sheet, or it may be formed by coating a thin resin layer containing the white pigment dispersed on the surface of the paper sheet. The thickness of the paper sheet with side 6 is usually 20
~100 μm.

Next, the transparent base layer 7, which is a resin layer made of transparent toner, is formed on the white reflective surface 6, which transmits visible light, has a melting point of 100° C. or more, and changes color when heated. Instead, a material such as a paper sheet and a resin layer having adhesive properties with the toner layer are used, and are selected from the following resins that are usually used for electrophotography.

[0018] Examples of the resin include styrene resin,
Acrylic resin, styrene-acrylic resin, styrene-butadiene resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic acid copolymer resin, polyester resin, polyurethane resin, polyimide resin , polyamide resin, epoxy resin, vinyl butyral resin, polyvinyl alcohol resin, etc. are used.

The transparent toner made of the resin has a transparent base layer 7 and/or a transparent coating layer 8 formed thereon so that the thickness of the fixed film on the white background reflective surface 6 is 5 to 40 μm, thereby producing a high-quality image according to the present invention. is obtained.

Next, as a color image forming method applied to the present invention, for example, a sharp color copying machine CX-750 is used.
Using a belt-shaped photoreceptor as in 0, each color C, M, Y, BK toner image is formed on the photoreceptor by an analog method,
Each time a color toner image is formed, it is transferred onto an intermediate transfer belt, a color toner image is formed by overlapping each color toner image on the belt, and the color toner image is transferred onto the specific transfer material. It may be fixed to form a color image. Furthermore, for example, as in the digital color copying machine described in Japanese Patent Application Laid-Open No. 61-111071, a color image signal is read out using a color scanner, and a laser beam modulated by the color image signal is imagewise exposed onto a photoreceptor. A color image may be formed by forming an electrostatic latent image, and then developing the electrostatic latent image by reversing it with C, M, Y, and BK color toners.

In this case, each color toner image formed on the photoreceptor is wound around a transfer drum each time a color toner image is formed, and is transferred onto a fixed transfer material. forming a color toner image in which the images are superimposed;
After the transfer material is released from the drum, it is fixed to form a color image.

Furthermore, in color image forming apparatuses such as digital color copying machines or color printers described in Japanese Patent Laid-Open Nos. 59-34546 and 59-61865, the image forming apparatus is Toner images of each color of Y, M, C, and BK are formed on the drum by overlapping them digitally to form a color toner image. The color toner images formed on the photoreceptor are collectively transferred and fixed onto the specific transfer material to form a color image. This color image forming apparatus has advantages such as particularly high overlay accuracy of toner images of each color and the ability to obtain color images with excellent resolution.

In any case, no matter which of the various color image forming methods described above is used, a deep, high-quality color image can be obtained by using the unique transparent toner particle layer forming method according to the present invention. .

[0024]

1 and 2 are diagrams for explaining the reflection state of illumination light when a color image of the present invention is formed using a transfer material, and the same reference numerals are given to the same contents as in FIG. 10. In the figure, 6 is a white background reflecting surface, 7 is a transparent base layer made of transparent toner particles, 8 is a transparent coating layer which is a resin layer made of transparent toner particles, 10a, 11a, 12a are ambient light,
10b, 11b, and 12b are the reflected lights. Normally, the white reflective surface 6 is not provided in the transfer paper, and it also serves as the transfer paper 1a. In FIG. 1, unlike the case in FIG. 10, in addition to the reflected lights 3Y, 3M, and 3C from the toner image layers 2Y, 2M, and 2C constituting the color image 2, there are also ambient lights 10a and 11a.
, 12a have a toner layer fixed thereto.
and reflected light 10b reflected via the white reflective surface 6,
11b, 12b, and 3E are added, the amount of light that reaches the naked eye is abundant, and a color image with rich tone and depth can be obtained. FIG. 2 shows an example in which a transparent coating layer 8 is formed by fixing a transparent toner particle layer on the color image of FIG. 1, and a color image with depth and gloss is obtained.

FIGS. 1, 2, and 10 here show exaggerated irregularities; in reality, they are melted and smoothed by the heat-generated fixing device.

[0026]

[Examples] The present invention will be specifically explained below with reference to Examples, but the embodiments of the present invention are not limited thereto.

(Example 1) (Y→M→C→Bk→W) FIG. 3 is a sectional view of a color image forming apparatus for explaining the image forming method of this embodiment, where K is an image reading section and L is a laser. Each unit of the writing section, M is an image forming section, and N is a paper feeding section.

The image reading section K includes a carriage 22 to which a mirror 25 and a halogen lamp 24 are attached, and a mirror 2.
A movable mirror unit 23 to which lenses 6 and 27 are attached, a lens 30, and a color CCD 3 having a color separation filter.
3 and an image processing device 34.

The laser writing section L includes a motor 41, a rotating polygon mirror 42, and the like. The image forming section M includes a photoreceptor 4 which is an image forming body provided with an organic photoconductive layer containing a bisazo pigment.
0, the pre-exposure lamp 45A, and the photoreceptor surface, for example, -
A scorotron-type charger 45B that charges to 700V, and a developer containing negative polarity toner of Y, M, C, BK and transparent (W) to which AC bias P1 and DC bias P2 are applied alternately only during development are filled. developed developing device 46Y, 4
6M, 46C, 46BK and 46W, and the photoreceptor 4
a transfer pole 47 that collectively transfers the color toner image formed on the photoreceptor 40 to a transfer paper as a transfer material; a separation pole 48; a fixing device 55 that fixes the color toner image; and toner remaining on the photoreceptor 40. Cleaning blade 49A that removes
A cleaning device 49 is provided.

The paper feed section D has feed rollers 51A and 51B and a timing roller 52 for feeding transfer paper PA or transfer paper PB as a transfer material from a paper feed cassette 50A or 50B to a transfer pole 47 and a separation pole 48. ing.

The transfer papers PA and PB were made of 50 μm thick high-quality paper, provided with a 1 μm thick polyvinyl butyral layer containing 25 wt% ZnO dispersed thereon, and further laminated with a 5 μm thick vinyl chloride-vinyl acetate copolymer resin layer. It is considered to be a composition.

The color image forming apparatus configured as described above performs image formation based on the time chart shown in FIG.

First, the copy button is turned on and an initialization signal is output to the image reading section K via the control circuit. Next, in the first rotation of the photoconductor, the image reading section K
The original 20 on the original platen 21 is optically scanned by the halogen lamp 24 of the carriage 22, and the optical image of the original is transmitted through the mirror group 25, 26, 27 driven by the stepping motor to the color CCD 33 through the lens 30. It is imaged onto a surface and converted into an electrical signal. The obtained electric signal is subjected to signal processing such as A/D conversion, shading correction, gradation correction, color conversion, ghost processing, and multi-value conversion in the image processing device 34 to produce a first color signal Y. The image signal is output to the next laser writing section L. The 810 nm laser beam oscillated from the laser source is pulse width modulated by the Y image signal, is rotated and scanned by a rotating polygon mirror 42 that is rotationally driven by a motor 41, passes through an fθ lens 43, and has its optical path bent by a mirror 44. Image exposure is performed on the photoreceptor surface which has been pre-exposed by a pre-exposure lamp 45A and uniformly charged by a charger 45B,
An electrostatic latent image is formed. This electrostatic latent image is transferred to the developing unit 46Y.
The two-component developer containing the Y toner contained in the A
A Y toner image is formed by developing using a non-contact reversal development method while applying C and DC biases. The obtained Y toner image, while being held on the photoconductor 40, passes under the cleaning device 49, which has already been separated from the surface of the photoconductor 40,
In order to form the next M toner image, the photoreceptor 40 is transported to the charger 45B as the photoreceptor 40 rotates for the second time.

That is, the photoreceptor 40 is negatively charged again by the charger 45B while carrying the Y toner image, and then the second image from the image processing device 34 is charged by the image reading section K during the next scan.
An electrostatic latent image is formed on the photoreceptor 40 by image exposure with a laser beam based on the M image signal, which is a color signal of An M toner image is formed superimposed on the image.

Thereafter, in the third and fourth rotations of the photoreceptor 40, image exposure with the laser beam based on the C image signal, development by the developing unit 46C, image exposure with the laser beam based on the BK image signal, and image exposure with the developing unit After development with 46BK, a C toner image and a BK toner image are superimposed on the Y toner image and the M toner image on the photoconductor to form a color toner image. Next, as a method of forming a transparent toner particle layer, the image reading section K, the charger 45B, and the laser writing section L are not operated, and non-contact reversal development is performed on the photoconductor 40 using the pre-exposure lamp 45A. After uniform pre-exposure is applied and the photoreceptor is neutralized, the developer 46W
A uniform transparent toner particle layer is formed on the photoreceptor 40 by non-contact reversal development. Another method for forming a transparent toner particle layer is to operate only the charger 45B without operating the image reading section K, laser writing section L, and pre-exposure lamp 45A to equalize the potential of the photoconductor, and then apply the charging to the photoreceptor. A uniform transparent toner particle layer can also be formed by applying a developing bias having a DC component higher than the potential to the developing sleeve and performing reversal development. Alternatively, after the charger 45B is operated to equalize the photoreceptor potential, the photoreceptor can be optically neutralized by uniform exposure of the laser writing portion L, and then transparent toner particles can be attached by reversal development. In this case, the black toner is preferably transparent to the laser beam. The transparent toner particle layer and the color toner image are transferred to the transfer paper PA (A4, horizontal feed ) is transferred all at once by the action of the transfer pole 47. In addition, 50B
is a cassette that accommodates B4, vertically fed transfer paper PB.

The transfer paper PA to which the transparent toner particle layer and the color toner image have been transferred is separated from the photoreceptor 40 by the separation pole 48 and then transferred to the heat roller fixing device 55 by the conveyor belt 54.
The sheet is conveyed to the printer and fixed by heat in the fixing device 55 to form a color image having a transparent toner particle layer as an underlying layer, and is discharged to a paper discharge tray 57 by a paper discharge roller 56.

In this embodiment, a negatively charged OPC is used, and each of the two-component non-contact developing devices 46Y, 46M, 46
The developer used for C, 46BK, and 46W is as follows.

Toner manufacturing method: Styrene-butyl methacrylate (75:25)
Copolymer resin 100 parts by weight Colorant

10 parts by weight
charge control agent
0.2 parts by weight Polypropylene with a softening point of 120°C
2 parts by weight of the above composition was melted, kneaded, cooled, crushed, and classified to -15 μc.
A toner having a diameter of 10 μm and having a charge amount of /g was obtained.

Manufacturing method of carrier: A 0.5 μm thick coating layer of styrene resin was formed on spherical ferrite particles having a diameter of 40 μm.

Preparation of developer: Mix the toner to the carrier at 5 wt%, and add 0% hydrophobic silica.
．． The amount was added to 5 wt% to prepare a developer.

The toner from which the colorant has been removed is called transparent toner, and the toner for the developer 46Y is benzidine yellow, the toner for the developer 46M is Rhodamine B, and the toner for the developer 46C is the toner. Copper phthalocyanine was used, and the toner for developing device 46BK was a blend of the above colorants. This black toner is transparent to laser light emitted from a semiconductor laser.

(Embodiment 2) (W→Y→M→C→BK) In this embodiment, as shown in FIG. ,46Y
. went.

As an image forming method, at the start of copying, the image reading section K, charger 45B and laser writing section L are not operated during the first rotation of the photoconductor, and a uniform image is formed on the photoconductor 40 by the pre-exposure lamp 45A. After applying the pre-exposure, non-contact reversal development is performed by the developing device 46W to form a uniform transparent toner particle layer on the negatively charged photoreceptor. Next, the image forming method of Example 1 consisting of charging, image exposure, and reversal development is performed on the transparent toner particle layer to superimpose a Y toner image, a M toner image, a C toner image, and a BK toner image to form a color toner image. was formed, and the color toner image containing the transparent toner particle layer was transferred all at once onto the transfer paper PA and fixed with a heat roller in the same manner as in Example 1 to form a color image having the transparent coating layer 8.

(Comparative Examples 1 and 2) Color images were formed in the same manner as in Example 1 and Example 2, except that no transparent toner was used.

The color images of Examples 1 and 2 both had deep image quality and were excellent in color tone, gradation, etc., and deep color images were obtained, but in the case of the comparative examples, none However, the color tone and gradation were poor, and only flat color images were obtained.

In particular, in Example 1, since the transparent toner is used last, it does not affect the superimposition of the color toner images on the photoreceptor and is favorable, and the transparent toner particle layer is placed in the lower layer on the transfer paper. More favorable results were obtained by forming the transparent base layer 7 from the above. Also, the order of use of color toner is B.
Similar favorable results were obtained when changing from k→C→M→Y.

(Embodiment 3) (BK→Y→M→C→W) This embodiment is an example of a color image forming apparatus using a transfer method as shown in FIG. 7 using a transfer drum 60. The developing device arrangement is the same as in No. 3. The same content as in FIG. 3 is given the same reference numeral.

In this embodiment, during the first rotation of the photosensitive drum 40, a BK image signal is first read by the image reading unit K similar to that in the first embodiment (FIG. 3), and the laser beam is modulated by this signal. , the modulated laser beam is rotated by a polygon mirror,
An electrostatic latent image is formed on the photoreceptor, which has been subjected to pre-exposure by a pre-exposure lamp 45A and uniformly charged by a charger 45B, through an fθ lens or the like.

This electrostatic latent image is subjected to non-contact reversal development by a developing device 46BK to which an AC bias P1 and a DC bias P2 are applied, and a BK toner image is formed on the photoreceptor 40. The leading edge of this BK toner image is held by the transfer drum 60 by a metal fitting 61, and is transferred onto the transfer paper PA wound and fixed on the drum 60 by the action of the transfer pole 47. During the second rotation of the photoconductor 40, the photoconductor 40, which has been pre-exposed and uniformly charged in the same way as before, is imagewise exposed by a laser beam modulated by the Y image signal, and is subjected to non-contact reversal development by the developing device 46Y. A Y toner image is formed on 40, and the Y toner image is superimposed and transferred onto the transfer paper PA carrying the BK toner image. Thereafter, in the third and fourth rotations of the photoreceptor 40, static images are formed using laser light based on the M image signal and the C image signal, and the developing units 46M and 4
After development with 6C, an M toner image and a C toner image are formed, and each image is superimposed and transferred onto a transfer paper to form a color toner image. Further, during the fifth rotation of the photoreceptor 40, the pre-exposure lamp 45A is
The photoreceptor 40, whose charge has been erased by pre-exposure, is subjected to non-contact reversal development under the application of biases P1 and P2 using a developing device 46W filled with a developer containing colorless toner excluding colorant to form transparent toner particles. A layer is formed, which is carried by the color toner image and transferred onto a transfer paper. Here, the separation claw 62 is operated to separate and convey the transfer paper PA from the drum 60, and fix it with a heat roller to form a color image having the transparent coating layer 8.

(Embodiment 4) (W→Y→M→C→BK) In this embodiment, non-contact reversal developing type developing devices 46W, 46Y, 46M, 46
Images were formed using a color image forming apparatus using the same transfer method as in Example 3, except that the toners were rearranged in the order of C and 46BK, and the transparent toner was developed first.

As an image forming method, at the first rotation of the photoreceptor 40 at the start of copying, the image reading section K, charger 45B and laser writing section L are not operated, and a uniform image is formed on the photoreceptor 40 by the pre-exposure lamp 45A. After applying the pre-exposure, a uniform transparent toner particle layer is formed on the negatively charged photoreceptor 40 by non-contact reversal development using the developing device 46W, and then the transfer paper PA
Transfer to. Next, the image forming method of Example 1 consisting of charging, image exposure, reversal development, and transfer is performed on the transparent toner particle layer to superimpose a Y toner image, a M toner image, a C toner image, and a BK toner image to form a color image. A toner image is formed, and the color toner image containing the transparent toner particle layer is transferred all at once onto the transfer paper PA and fixed with a heat roller in the same manner as in Example 1 to form a color image with the transparent base layer 7 of transparent toner as the lower layer. form.

(Comparative Examples 3 and 4) Color images were formed in the same manner as in Examples 3 and 4 except that no transparent toner was used. The color images of Example 3 and Example 4 both had deep image quality, excellent color tone, gradation, etc., and deep color images were obtained.
Since the transparent toner was placed in the lower layer on the transfer paper, more favorable results were obtained. Also, change the color toner usage order to Y.
Similar favorable results were obtained when the sequence was changed to →M→C→Bk. However, in the case of the comparative examples, the color tone, gradation, etc. were poor, and only flat color images were obtained.

(Embodiment 5) In this embodiment, as shown in FIG. 8 for the photoreceptor 40, the developing device 46W of the non-contact reversal developing method in the case of Embodiment 1 is abolished, and the developing device 46 is replaced by 46Y, 4.
Arrange 6M, 46C, 46BK in order and start from Y toner to B.
After developing the K toner, the conveyor belt 70 is placed between the timing roller 52 and the fixing device 55, and the conveyor belt 70 is
Developing device 4 containing developer containing transparent toner at both ends of 0
6W1 and 46W2 are arranged, and the transfer pole 47 and separation pole 4
In No. 8, image formation was performed using the same color image forming apparatus as in Example 1, except that the action was applied from the back side of the conveyor belt 70.

As an image forming method, at the start of copying, the image forming method consisting of charging, image exposure, and reversal development of Embodiment 1 is carried out during the first rotation of the photoreceptor to form a Y toner image, a M toner image, and a C toner image. A uniform transparent toner particle layer is formed on the transfer paper PA or PB fed by the timing roller 52 by the developing device 46W1 to which a sufficiently high DC bias is applied. form. The color toner image is transferred at once to the transfer paper PA or PB on which the transparent toner particle layer is formed by the transfer pole 47 and separated from the photoreceptor 40 by the separation pole 48, and then further transferred to the developing unit 46W2.
The color toner image in which a transparent toner particle layer was formed on the color toner image was fixed by a hot roller fixing device 55 to form a color image having a transparent base layer 7 and a transparent coating layer 8. The developing units 46W1 and 46W2 are 2
Although non-contact development using a component developer is preferable, the developing device 46W1 can also be a contact development using a one-component developer. Of course, it is possible to use one or both of the developing devices 46W and 46W2.

(Embodiment 6) As shown in FIG. 9, this embodiment is an example of a color image forming apparatus using a transfer method using a transfer drum 60 as in Embodiment 3. The developing device arrangement is the same as in Example 3, but the developing device 46
W is excluded. Further, a developing device 46W1 similar to that of the fifth embodiment is arranged around the transfer drum 60, and a developing device 46W2 similar to that of the fifth embodiment is arranged in the path upstream of the fixing device for the transfer paper PA.

In this embodiment, the transfer paper P on the transfer drum 60
A transparent toner particle layer is formed by the developing device 46W1, and the toner images of each color formed on the photoreceptor 40 in the same manner as in Example 3 are transferred to the transfer paper PA on the transfer drum 60.
The toner toner is transferred onto the top by the action of the transfer pole 47 and superimposed to form a color toner image. Thereafter, the transfer paper PA is conveyed to a fixing device, and at this time, the color toner image with a transparent toner particle layer formed on the color toner image is fixed by the heat roller fixing device by the developing device 46W2 to form a transparent base layer. 7 and a transparent coating layer 8 is formed. The developing unit 46W1 can be arranged not only at the position shown by the solid line in FIG. 9 but also at the position shown by the broken line. Of course, one or both of the developing devices 46 and 46W2 can be used.

In Examples (1) to (6), the transparent toner layer was provided as an upper layer or a lower layer, but it goes without saying that it can be used both as an upper layer and a lower layer of a color toner layer.

The present invention also has the effect of preventing diffuse reflection on films made of transparent substrates such as OHP, and provides the same favorable effect on images.

[0059]

As is clear from the above description, according to the color image forming method of the present invention, a color image is formed by forming a color toner image on a substrate and further forming a transparent coating layer on or below the color toner image. As a result, it is possible to obtain a color image with excellent color tone and gradation, and a depth similar to that of a silver salt color image.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the state of reflected light in an example of a color image according to the present invention.

FIG. 2 is a diagram illustrating the state of reflected light in another example of a color image according to the present invention.

FIG. 3 is a sectional view showing a color image forming apparatus of Example 1 to which the present invention is applied.

FIG. 4 is a time chart of the image forming process in Example 1 of the present invention.

FIG. 5 is a diagram showing the arrangement of each developing device in Example 2 and Example 4 of the present invention.

FIG. 6 is a time chart of an image forming process in Example 2 of the present invention.

FIG. 7 is a diagram showing the arrangement of various devices around the photoreceptor in Example 3 using the transfer drum of the present invention.

FIG. 8 is a diagram showing the arrangement of devices around a photoreceptor in Example 5 of the present invention.

FIG. 9 is a diagram showing the arrangement of devices around a photoreceptor in Example 6 of the present invention.

FIG. 10 is a diagram illustrating the state of reflected light in a conventional color image.

[Explanation of symbols]

1, PA, PB Transfer paper 2Y, 2M, 2C Color toner layer 3Y, 3M, 3C, 3E, 10b, 11b, 12b, 3
0 Reflected light 6 White reflective surface 7 Transparent base layer 8 Transparent coating layer 20 Original 22 Carriage 25 Movable mirror unit 32 Color separation filter 33 CCD 40 Photoreceptor 45 Charger 46Y, 46M, 46C, 46BK, 46W, 46W1
, 46W2 Developing device 47 Transfer pole 49 Cleaning device 60 Transfer drum 61 Paper leading edge clamp 70 Conveyor belt K Image reading section L Laser writing section M Image forming section N Paper feeding section P1, P2 Bias

Claims (3)

[Claims] Claim 1. A color image forming method comprising a step of transferring and fixing a toner image on an image forming body to a transfer material,
A color image forming method comprising the step of attaching a transparent toner particle layer to a substrate as the transfer material and fixing it. 2. A color image having a transparent coating layer by forming a transparent toner particle layer on the image forming body in addition to the toner image, and transferring and fixing the toner image and the transparent toner particle layer onto a transfer material. 2. The color image forming method according to claim 1, wherein: 3. A transparent toner particle layer is formed on the transfer material by direct non-contact development, and the toner image formed on the image forming body is transferred to form a toner image on the transfer material. 2. The color image forming method according to claim 1, wherein a color image having a transparent coating layer is formed by forming and fixing the transparent toner particle layer.