JPS62299872A - Color image forming device - Google Patents

Abstract

PURPOSE:To reduce the cost of toner which is free from image disorder and color mixing and has superior granularity and forms a sharp color image by using such a developer that the granularity distribution range of toner is increased gradually according to the order of development. CONSTITUTION:A color toner image is charged electrostatically and exposed by a before-transfer processor 15, transferred to a transfer material P supplied by a feeding means by a transfer electrode 10. The transfer material which carries the transferred color toner image is separated from a photosensitive body 41 by a separation electrode 11. The image is fixed by a fixing device 13 to obtain a complete color image, which is discharged from the machine. When development is performed, the developer which is increased in the granularity distribution range of toner according to the order of development is used; and a developing bias voltage containing an AC component is applied between the photosensitive body and a developing device which supplies the developer and the AC component frequency is increased gradually according to the development order. Consequently, the granularity is made superior, and no toner returns, so that a sharp color image having no disorder is obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a color image forming apparatus, and more specifically, the process of forming a latent image on an image carrier, and the process of forming a latent image on an image carrier, The present invention relates to a color image forming apparatus having steps of sequentially supplying a yellow developer onto the image carrier to form a visible image on the image carrier.

[Background of the Invention 1 The present applicant previously filed Japanese Patent Application No. 59-83096;
No. 187044, J No. 60-229524, etc., charge and imagewise expose a photoreceptor having a color separation filter, an insulating layer on the surface, and a color separation function in the plane. Later, he proposed a method for forming color images in which a color image was obtained by repeating full-surface exposure with specific light and development.

Figure 1 shows an example of layered photoreceptor used in the above color image forming method, and 1 is a conductive cylindrical or belt-shaped base made of aluminum or nickel. , 2 is a photoconductive layer or a functionally separated photoconductive layer consisting of a charge generation layer and a charge transfer layer; 3 is red (R) formed from various polymers, resins, etc. and colorants such as dyes or pigments; This is an insulating layer including a layer consisting of color separation filters such as green (G) and blue (B). Fig. 2 shows the insulating layer 3, and the filter layer provided on the insulating layer may have a striped distribution as shown in Fig. 2(a), or a mosaic pattern as shown in Fig. 2(1)). A type of distribution is used.

However, the arrangement pattern of the filter layer is not limited to this. Furthermore, the number of color separation filters per unit area does not have to be the same, and the number of green (G) color separation filters may be increased in accordance with human visibility. Here, the length I of each filter portion, indicated by I in the figure, is 10 to 5, which is a good condition for image resolution and color reproducibility.
A volume in the range of 00 μl is used. Red (R), Green (G
), blue (I3) color separation filters are filters that transmit only red light, green light, and blue light, respectively, and the transmittance for each filter wavelength is as shown in FIG. 3, for example.

The applicant has developed a color separation filter in which a photoreceptor as described above is subjected to imagewise exposure, and then developed through full exposure with light that passes only through a specific color separation filter. We proposed a color image forming method that obtains color images by repeating the process for different types of parts. At this time, color toner of a color complementary to the color light transmitted through each filter, as modeled in Figure 4, is used for development, and a multicolor image is formed on the photoreceptor. A multicolor image is recorded on the transfer material at once by multiple transfers. Regarding this, the present applicant has disclosed in Japanese Unexamined Patent Publication No. 60-154271 that a latent image is formed on an image carrier such as an electrophotographic photoreceptor, and the latent image is formed by a plurality of developing devices provided at the peripheral edge of the image carrier. We have proposed a color image forming method in which a color visible image is formed on an image carrier by repeating the developing process multiple times.

The invention described in Japanese Patent Application Laid-Open No. 60-154271 provides that the image bearing member and the image carrier are
If an electric field containing an alternating current component is generated between the portrait developing device and the frequency of the alternating current component is increased sequentially, then by sequentially increasing the frequency of the alternating current component, and by sequentially using a developer with a large charge amount for each development, the subsequent development can be performed. This prevents the toner that has already adhered to the image bearing member from the previous stage of development from returning, allowing the latter stage of development to be performed without disturbing the image formed on the image bearing member by the previous stage of development. be. As a result, even if a color image is formed by repeating development on the image carrier multiple times and overlapping toners of multiple colors, a clear image without any disturbance can be obtained.

[Problems to be Solved by the Invention] However, in the above-mentioned technology, the order of the developer of each color and the particle size when using the developer with a sequentially large amount of charge for each development are not yet clear. It wasn't.

Therefore, there is still room for improvement in the sharpness of images obtained by overlaying.

The present invention has been made to solve these problems, and an object of the present invention is to provide a color image forming apparatus that can obtain clearer images without distortion.

Means for Solving Problem F] The above l] target is a step of forming a latent image on an image carrier, and sequentially supplying magenta, cyan, and yellow developers onto the image carrier. This is achieved by a color image forming apparatus characterized in that it uses a developer in which the particle size distribution range of the toner is gradually increased according to the order of development.

1 Effect 1 It is well known that the image quality of a color image formed by a color image forming apparatus is greatly affected by the graininess of the image.

Furthermore, the degree of contribution of each color toner to the graininess of the color image is as follows: yellow toner 1, cyan toner 5,
It is also known that magenta toner can be expressed as 10, where the contribution of magenta toner is the largest,
It is also known that the contribution of yellow toner is the smallest, followed by cyan toner. Therefore, it is necessary to thin the magenta toner particles with the largest dual contribution.

Next, considering the relationship between the toner particle size and the amount of charge, it is known that the larger the toner particle size, the larger the amount of charge. However, the more charged the toner particles are, the more easily they are affected by the frequency of the alternating current electric field. Therefore, the toner particles to be developed first are made the smallest, and then the toner particles to be developed are By making the particles larger than the toner particles to be developed in the first stage, and by making the frequency of the alternating current component of the developing bias higher than the frequency of the alternating current component of the developing bias used in the previous stage development, The phenomenon in which toner adhering to the body drum returns to the developing sleeve can be extremely reduced.

In color image formation, the color mixing phenomenon that occurs when toner that has adhered to the photoreceptor drum returns to the developing sleeve has a negative effect on image quality.Furthermore, if the average particle size of toner particles becomes too small (for example, 2++a+ or less) Since the amount of charge of the toner decreases, it will adhere to areas other than the latent image and cause fogging, so it is desirable that the particle size of the toner particles be about 3 nm or more.

It is unavoidable that toner has a particle size distribution within a considerable range during the manufacturing process, and if the toner is developed with a toner that has a wide particle size distribution and contains many coarse particles,
Only color copies with poor graininess can be obtained. Therefore, image quality deteriorates. Therefore, in order to obtain high-quality color copies with good graininess and fine texture, it is desirable to use yellow, cyan, and magenta toners that have a narrow particle size distribution range and are uniform in particle size. However, toner with a narrow particle size distribution is obtained by sizing and sorting the toner obtained through the manufacturing process.
Due to yield considerations, it is not possible to obtain a similarly narrow particle size distribution for all toners.

Considering the above factors, the particle size distribution range of magenta toner, which contributes most to image graininess, is made the smallest, that is, the average particle size is made the smallest, and regarding cyan toner and yellow toner, The particle size distribution range of the cyan toner is made smaller than the particle size distribution range of the yellow toner, and development is performed in the order of toners with a smaller average particle size and a smaller amount of charge. That is, by performing development in the order of magenta, cyan, and toner, it is possible to prevent an increase in toner manufacturing costs that would be required to improve the graininess of an image by reducing the particle size distribution range of all toners.

Experiments have also confirmed that within the toner particle size range that does not cause fogging, thinner toner particles adhere better to the image carrier, and magenta toner has the largest contribution to image sharpness. By improving the degree of adhesion of magenta toner, the density of magenta toner can be made sufficient, and the clarity of the color image formed can be improved.

[Embodiment 1] FIG. 5 is a diagram showing the configuration of a 1-m image forming apparatus according to an embodiment of the present invention, and FIG. 6 is a diagram showing the configuration of an example of a developing device used in the above color image forming apparatus. It is a diagram.

In FIG. 5, reference numeral 41 denotes a photoreceptor which is an image carrier having the structure shown in FIG. 1, and rotates in the direction of arrow a during a copying operation. While rotating, the photoreceptor 41 is irradiated with light as needed, and the entire surface is charged with the charging electrode 4, and the next exposure slit is provided. ! ! Image exposure of the document is applied while receiving alternating current or corona discharge of opposite polarity to the electrode 4 from the pole 5, and the first latent image forming process is completed. Next, the entire surface is exposed to green light from the light source 6G to form a second latent image of the magenta component.

Next, this is the developer 7M that used magenta toner.
It is developed with Subsequently, in order to avoid color mixing with the cyan toner to be developed next, the surface of the photoreceptor is smoothed by an electrode 8 having a polarity opposite to that of the electrode 4, and then the entire surface is exposed to red light from the light source 6R to make the cyan component secondary. A latent image is formed and developed by a developing device 7C loaded with cyan toner. Further, the potential of the photoreceptor is smoothed by an electrode 9 having a polarity opposite to that of the electrode 4 in order to avoid color mixing with the yellow toner to be developed next.

Next, a second latent image of a yellow component is formed by exposing the entire surface to blue light from the light source 6B, and is developed by a developing device 7Y loaded with yellow toner. As a result, a color image consisting of magenta, cyan, and yellow toners is formed on the photoreceptor. The obtained color toner image is charged and exposed by a transfer pretreatment device 15, and transferred to a transfer electrode 1 on a transfer material P supplied by a feeding means (not shown).
Transcribed by 0. The transfer material carrying the color toner image to be transferred is separated from the photoreceptor 41 by the separation electrode 1 and fixed by the fixing device 113 to form a completed color image, which is discharged outside the machine. After the transfer, the photoreceptor 41 is irradiated with neutralizing light, neutralized by the neutralizing electrode 12, and the toner remaining on the surface is removed by the cleaning plate 14, before being used again.

FIG. 6 shows the developing devices 7M and 7C shown in FIG.

This shows the basic structure of 7Y, in which the developer De is conveyed on the circumferential surface of the sleeve 17 in the direction of arrow B by rotating the sleeve 17 and/or the magnetic roll 43, which are developer conveying bodies. The developer De is supplied to the development area IΣ.

The magnetic roll 43 is in the direction of arrow A, and the sleeve 17 is in the direction of arrow r3.
) By rotating in the j direction, the developer DC is rotated in the direction of arrow I3.
conveyed in the direction. The thickness of the developer De is regulated by a spike regulating blade 40 made of a magnetic material during transportation. A stirring screw 42 is provided in the developer reservoir 47 to sufficiently stir the developer Dc, and when the toner in the developer reservoir 47 is consumed, the toner supply roller 39 rotates. As a result, toner T is replenished from the toner hopper 38.

A DC power supply 45 and an AC power supply 46 are provided in series between the sleeve 17 and the photoreceptor 41 to apply a developing bias. R is a protective resistance.

When development is performed by the apparatus described above, a developer whose toner particle size distribution range is gradually increased according to the order of development is used, and during the development, the photoreceptor and a developing device that supplies the developer are used. By applying a developing bias voltage containing an alternating current component at the opening, and increasing the frequency of the alternating current component in sequence according to the development order, it is possible to obtain clear color images with excellent graininess, no toner return, and no disturbance. Ta.

Two specific examples of the particle size distribution of color toners from which images of high quality and good graininess were obtained are as follows.

-11 = Table 1 Table 2 In addition, when the toner according to Table 1 was used in the binary embodiment, a better image was obtained compared to when the toner shown in Table 2 was used. Rarena.

Note that the present invention can be applied not only to electrophotographic recording methods but also to non-impact printers using electrostatic 11-type and magnetic recording methods.

[Effect of the Invention 1] As explained above, according to the present invention, the particle size distribution range of the toner is gradually increased in the developer used in the development according to the development order, and during the development, the particle size distribution range of the toner is gradually increased. An electric field containing an alternating current component is generated in the area, and the frequency of the alternating current component is increased in sequence according to the development order.This produces clear color images with excellent graininess and no image holes or color mixture without increasing toner production costs. It has the effect of being able to obtain two things.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the N configuration of the photoconductor of the present invention, FIG. 2 is a diagram showing an insulating layer of the photoconductor, and FIG. 3 is a spectral spectrum of a color separation filter of the photoconductor. FIG. 4 is a diagram showing the spectral reflectance of each color toner, FIG. 5 is a diagram showing the configuration of a color image forming apparatus which is an embodiment of the present invention, and FIG. 7196 is a diagram showing -I-. 1 is a diagram showing the configuration of an example of a developing device used in a color image forming apparatus. In the figure, 1... conductive substrate, 2... photoconductive layer, 3...
・Insulation 1 (4, 4... charged electrode, 510. electrode,
6G, 6R, 6B...Light source 7.7N, 7C, 7
Y... Developing device, 8, 9... Electrode, 10... Transfer electrode, 11... Separation electrode, 12... Static elimination electrode, 13... Fixing device, 14... Cleaning blade, 17... Sleeve 41... Photoreceptor,
43...Magnetic roll 45...DC type @
46...AC power supply, De...developer,
L: Image exposure, P: Transfer paper, B: Blue filter portion, G: Green filter portion, R: Red filter portion, T: Toner. Applicant: Roku Konishi Photo Industry Co., Ltd. Figure 1: red color Climb angle: Figure 2 (tz'') Figure 2 ζb) Figure 3: 6: s44 production no 7 nisi 3 7゛ 40 ii Sl J'l plate conduit 2 nio dou zuku gue 43: Negative Ishimori, Rohtsumsha: Yuryu electric thread p6: Stop pay side cutting bee

Claims (2)

[Claims] (1) A step of forming a latent image on an image carrier, magenta,
In an image forming apparatus having a step of sequentially supplying cyan and yellow developers onto the image carrier to form a visible image on the image carrier, the particle size distribution range of the toner is gradually changed according to the order of development. A color image forming apparatus characterized by using enlarged developer. (2) In the development, an electric field containing an alternating current component is generated between the image carrier and a developer transporting member that supplies developer, and the frequency of the alternating current component is increased in sequence according to the development order. A color image forming apparatus according to claim 1.