JPS63148274A - Formation of multicolor image - Google Patents

Abstract

PURPOSE:To hold a surface potential constant regardless of the histories of respective positions and to form a multicolor image free from image noises and color mixing by exposing an image formation body which has a photoconductive layer uniformly to light having a component which is transmitted through all of toner sticking on the image formation body. CONSTITUTION:The image formation body 1 is exposed uniformly by a before-charging exposure lamp 35, and then the surface is charged electrostatically and uniformly by a corona charger 21 and image exposure light L based upon recording data is projected on the image formation body 1 from a laser optical system 26. An electrostatic latent image which is thus formed is developed by a developing device 5A which contains 1st toner T1. The image formation body 1 where a toner image is formed is exposed uniformly by the before-charging exposure lamp 35 again, charged electrostatically and uniformly by the corona charger 21, and exposed to image exposure light L based on recording data of another color component. A formed electrostatic latent image is developed by a developing device 5B which contains 2nd toner T2. Consequently, the surface potential of the image formation body becomes constant regardless of the histories of respective positions to form stably a multicolor image which has neither noises nor color mixing.

Description

Detailed Description of the Invention Attachment (I) Claims Attachment (II) (2) On page 6 of the specification tube, line 4, "for the second time or later" has been changed to "for the second time or later due to the memory effect of the photoconductive layer." Correct the following.

(3) Page 6, lines 7-8 Delete/correct "(Figure 8 shows...)".

(4) The entire text of page 6, lines 11 to 19 is written as ``It adheres to the image area, causing ghosts, image noise, and color distortion.

In order to solve this problem, a method is known in which uniform exposure is performed before each charging process. However, if the uniform exposure is blocked by the toner image formed on the image forming body at this time, the difference in potential between the area to which toner is attached and the area to which toner is not attached increases. The shielding effect of this toner is remarkable with high-density black toner.

The potential of such a portion to which the toner is attached does not decrease, so there is no effect of uniform exposure. Further, since the potential of the portion to which no toner is attached decreases, the surface potential in this vicinity becomes as shown in FIG.

Under this situation, some of the toner T constituting the toner image leaves its original location and scatters to the periphery or floats inside the device.
Contaminate the inside.

This phenomenon is caused by the fact that the toner T1 is subjected to a strong electrostatic force in a direction parallel to the surface of the image forming body. This situation is shown in FIG. The arrows are lines of electric force, and the photoconductive layer 1
The positively charged toner T adhering to 2 receives a force in this direction.

The image smearing phenomenon causes blurring of the edges and thin lines of the image, noise of halftone dots, etc., and deteriorates the image quality. ” he corrected.

(5) The gold text on page 7, line 5 to page 8, line 12 reads: [The above purpose is to uniformly expose an image forming body having a photoconductive layer, uniformly charge the image forming body, and In a multicolor image forming method in which a latent image is formed by exposure, the latent image is developed with toner, and the above steps are performed multiple times to form a multicolor toner image on the image forming body, the uniform exposure is This is achieved by a multicolor image forming method characterized in that it is carried out using light having a component that transmits all of the toner attached to the image forming body.

[Effect 1] The problem with the conventional pre-charging exposure is due to the difference in spectral transmittance characteristics of each toner. In other words, when the toner is exposed to light, the effective amount of exposure that reaches the image forming body is calculated by multiplying the intensity of the light irradiated by the exposure means, the transmittance of the toner, and the photosensitivity of the image forming body with respect to the wavelength. Depends on the integrated value. For a specific uniform exposure, this integral value becomes small;
The problem mentioned above occurs.

FIG. 6 shows an example of spectral transmittance characteristics of yellow, magenta, and cyan toners. It can be seen that when white light, for example, is used as the pre-charging exposure, the effective amount of exposure depends on the toner present on the image forming member.

The inventor discovered a common wavelength range in which each toner has no absorption, and when the majority of the spectral distribution is uniformly exposed to light in that wavelength range before each charging process, the light is absorbed onto the image forming body. The present invention was developed by focusing on the fact that each toner passes through the photoconductive layer of the image forming body to obtain approximately the same amount of exposure. Transmission here means, of course, that it is sufficient to provide a sufficient amount of light to substantially smooth the surface potential of the image forming member.

By the way, in the multicolor image formation according to the present invention, when developing toners by overlapping them at the same position on the image forming body, it is inevitable that the contrast of the latent image potential gradually decreases due to the charge of the toner developed first. . For this reason, especially 3
When overlapping colors, the amount of third color toner attached is insufficient. According to the principle of subtractive color mixing, it should be possible to reproduce black from yellow, magenta, and cyan toners, but color reproduction becomes extremely difficult due to the imbalance of the latent images as described above.

For the above reasons, it is preferable to use black toner in addition to yellow, magenta, and cyan toner.

Conventional black toner using carbon black as a colorant has a wide absorption wavelength range, and absorbs not only visible light but also almost all light in the wavelength range to which the photoconductive layer of the image forming member is sensitive. After such a toner image is formed using black toner,
If uniform exposure is performed before charging, the light will be absorbed by the black toner, causing the problems described above. This problem can be avoided if the black toner is developed last, but at positions where it should overlap with other colors, the contrast of the latent image potential decreases, making it difficult for the black toner to adhere. As a result, the black density decreases, text becomes unclear, and
Shadows in intermediate color areas are less likely to appear. For these reasons, it is preferable to develop the black color first. Therefore, it is not enough for the homogeneous II light in this case to pass through the yellow, magenta, and cyan toners, but it must also pass through the black toner. For this purpose, the spectral transmittance characteristics of the black toner must be such that it transmits in the same wavelength range as other toners.

Conventionally, as a black toner using a colorant other than carbon black, Japanese Patent Application Laid-Open Nos. 48-63727 and 57-11
9363, 58-150967, 60-23976
9 and the like are known. In these, it has been proposed to use the black toner for transferring a monochrome toner image, cleaning an image forming body, or detecting toner concentration. In the present invention, if the toner image formed on the image forming body contains black toner, it is necessary that the black toner as well as the other color toners uniformly transmit the exposure light. Therefore, as long as the transmission wavelength range of black toner is common to the transmission wavelength range of other color toners, and the pre-charging exposure has that wavelength component,
The black toner described in the above-mentioned publication can be used. ” he corrected.

(6) The entire text of lines 4 to 5 on page 1 O is written as [A two-color toner image is formed. Similarly, the third toner (developing device 5C) and the fourth toner (developing device 5D)
are developed in a superimposed manner and corrected as "image forming body l".

(7) Page 14, line 18, eyelet: [Next, an experimental example for selecting a means for providing uniform exposure according to the present invention will be shown. Figure 6 shows an example of the spectral characteristics of toner.''

(8) On page 15, lines 1 to 6, make the eyelet [. Toner is uniformly spread on this adhesive surface to melt and smooth the adhesive surface. Measure the spectral transmittance after it is dry. This is corrected by the spectral transmittance of an OHP sheet with inner tape pasted, and is shown in a graph as the spectral transmittance of the toner.

For this measurement, a spectrophotometer manufactured by Hitachi (HITA) was used.
CHl 330 type), the wavelength range is 360 to 850n.
The range is a+. ” he corrected.

(9) In the 8th line of page 16, the following is an example of a black toner. In order to apply the present invention to a black toner, an example of a black toner is shown below. were mixed.

■ Pigment Yellow 97; 3.5
Part ■ Pigment Red 146; 4
Part ■ Pigment Blue 15:3;
3 parts of the above pigment Main resin (polyester resin) Iloo part Mold release agent (wax): 6 parts Pigment
; 5 to 10 parts The mixture was mixed in the above weight ratio, melted and kneaded, crushed and classified to obtain a black toner.

For toner having the above spectral characteristics, the pre-charging exposure lamp 35 emits infrared light.''

(10) After the first line of page 17, it says, ``The effect of the present invention does not change regardless of the order in which the above-mentioned toners are developed.Also, when three color toners other than black toner are used, etc. It goes without saying that it is also effective for

(11) The text in lines 13 and 14 on page 19 is corrected to read, "Figure 5 shows the spectral transmittance characteristics of an infrared transmission filter."

Figure 6 5L length (nm)

Claims (2)

[Claims] (1) An image forming body having a photoconductive layer is uniformly charged, imagewise exposed to form a latent image, the latent image is developed with toner, and all the toner adhering to the image forming body is removed. A multicolor image forming method, wherein the image forming body is uniformly exposed to light having a transmitting component, and the above steps are repeated a predetermined number of times to form a multicolor toner image on the image forming body. (2) The multicolor image forming method according to claim 1, wherein the uniform exposure is performed with light having a spectral distribution having a peak in a non-visible region.