JPS60151663A - Color image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image forming apparatus, and more particularly, the present invention relates to a color image forming apparatus, and more particularly, a multicolor image formation process is performed by performing a series of latent image formation and development steps.
This invention relates to a color image forming apparatus capable of

Conventionally, when forming full-color images based on electrophotography, etc., a latent image formation process based on color-separated light images of red, green, and blue, and a corresponding cyan, magenta, and yellow development process are performed.
For each color, the developed images formed in each step are sequentially transferred onto a transfer material to obtain a final image. For this reason, it is necessary to repeat the latent image forming step and the developing step according to the color separated light image three times in total for each color separated color, resulting in a long process time. Furthermore, when each developed image is transferred onto a transfer material, it may be difficult to maintain good color reproducibility of the formed image due to transfer failure or offset.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color image forming apparatus capable of eliminating the above-mentioned drawbacks and forming color images at high speed.

To achieve this object, the present invention forms an electrostatic latent image corresponding to the color components of the original image on an image carrier using reflected light obtained by sequentially irradiating the original image with light having a plurality of different wavelength distributions, The color image forming apparatus is characterized in that the electrostatic latent image is developed with a charged developer of a color corresponding to each color component at a time difference synchronized with the sequential irradiation.

Examples of the present invention will be described in detail below.

FIG. 1 is a schematic diagram of an embodiment of a color image forming apparatus to which the present invention is applied. ■ is a rotating photoreceptor, cylindrical #400
It consists of a mesh screen, in detail, a conductor such as a metal is covered with a cadmium sulfide (CdS) photosensitive layer, and its surface is further covered with an insulating layer. A porous material layer 2 is formed inside the screen mesh 1 and rotates therewith.

3 is a rod-shaped /\logen lamp for image exposure, 5 is its reflective umbrella, and 6 is a cylindrical rotary filter for red (R) and green (G).
) and blue (B) color filters 6R16G and 6
B is divided into 6 equal parts of 2 each. , 7 is slit, 8
・9 and 10 are cylindrical lenses, 12 is a photocell with red light sensitivity, and 14 is a document table on which document O is placed and arrow a
move in the direction. 15 around the photoconductor l is a primary charger, 13 is a full-surface exposure lamp, 16 is a charge removal device during exposure, 1
7a and 17b are paper feed rollers, 18 is a transfer charger, 19a
- 19b is a paper ejection roller. 20, 30-40 are used to develop each color of yellow, magenta, and cyan using ink cartridge arrays. 60 is a cleaning tank, 61 is a solvent, and 63 is a heater serving as a drying means.

FIG. 2 shows an enlarged view of the periphery of the inkjet arrays 20-30 and 40.

Each inkjet array 20-30-40 has a photoreceptor l.
A large number of nozzles are arranged along the longitudinal direction at a ratio of 5 nozzles per 1 mm. A piezo vibrator 26 is attached to the rear end of the inkjet array 20, and the vibrator 26 is connected to an AC power source 28. inkjet array 20
In front of the nozzle, a pair of charging electrodes 21a and 21b,
A pair of deflection electrodes 22a and 22b and a gutter 27 are arranged, and mist catchers 23a and 23b are disposed with slit openings between these gutter 27 and the surface of the photoreceptor l. A power source 24 is connected to the charging electrode 21a,
A pulse voltage source 25 that receives a signal from the photocell 12 and generates a pulse is connected to the deflection electrode 22a. The inkjet arrays 30 and 40 also have a similar configuration. That is, 31a, 31b and 41a-41b are charging electrodes, 32a-32b and 42a-42b are deflection electrodes, and 3
3a-33b and 43a/43b are mist catchers,
34 and 44 are power supplies, 35 and 45 are pulse voltage sources, 3
6 and 46 are piezo vibrators, 37 and 47 are garters, 3
8 and 48 are AC power supplies.

The operation of the embodiment of the present invention configured as above will be explained.

The photoreceptor 1 rotates in the direction indicated by the arrow at a circumferential speed of 50 cm/sec, and the surface of the photoreceptor 1 is uniformly charged by corona discharge from the primary charger 15. The light emitted from the halogen lamp 3 becomes a parallel beam of light through the synchronic lens 8, and the light is turned into a parallel light beam by the synchronous lens 8, and the light is passed through the filter 5 (6R16G or 6R16G) rotating in the direction of arrow C.
After passing through B), it is focused on the surface of the document 0 on the document table 14 via the slit 7 and another cylindrical lens 9. What about filter 6? , is rotated in the direction of the arrow at a high circumferential speed of 500 rpm, and each color filter 6R16G
, 6B and irradiates the document 0 at a fixed timing with either the red light, the green light, or the blue light that has passed through them. Since the document O is moved at a constant speed in the direction of the arrow a, red light, green light, and blue light are sequentially reflected at different positions on the document surface and at different times. The light thus reflected from the document surface is irradiated onto the screen surface of the photoreceptor l through the cylindrical lens 10, and an image is formed.

Simultaneously with this image formation, the charger 16 performs charging with a polarity opposite to the primary charging (or alternating current). Thereafter, the surface of the photoreceptor is uniformly exposed to light from the full-surface exposure lamp 16, and red light, green light, and blue light are repeatedly applied to the photoreceptor surface L in the order of light reflected from the original O. Accordingly, an electrostatic latent image is formed in a divided manner with a width of 15 trees per 1III11, respectively.

The electrostatic latent images corresponding to the respective reflected lights of red, green, and blue, which are dividedly formed along the rotational direction of the photoreceptor l, are transferred to inkjet arrays 20, 30-40 whose charge is continuously controlled. are developed (visualized) with yellow (Y), magenta (M), and cyan (C) ink in synchronization with the respective latent images.

This synchronous developing means will be described below.

The Pietz oscillator 26-3 is activated by the high frequency voltage supplied by the high frequency AC voltage sources 28, 38 and 48 provided corresponding to the inkjet arrays 20, 30 and 40.
6 and 46 act to dispense ink drops 29, 39 and 49 from their respective arrays. This ink droplet is formed between a pair of electrodes 21a and 21b to which a DC voltage is applied.
, 31a-31b and 41a, 41b, the electrostatic latent image on the photoreceptor 1 is charged with a polarity opposite to that of the electrostatic latent image.

The pulsed voltage source 25 can finely adjust the voltage and phase of the generated pulsed signal, or the duregio, so that the yellow ink droplets 29 are developed in synchronization with the latent image formed by the blue light. Similarly, pulse voltage sources 35 and 4 are applied so that magenta and cyan ink droplets 39-49 develop latent images formed by green light and red light respectively.
5 pulse signal can be finely adjusted.

When there is a pulse voltage TX25.35 and a synchronizing signal from the photocell 12, the deflection electrodes 22a-22b, 32a-3
Since an electrostatic field is formed between 2b and 42a-42b, the charged ink droplets are deflected when passing between the deflection electrodes, and the mist catchers 23ae23b, 33
It reaches the surface of the photoreceptor through each of the slits a-33b and 43a and 43b. Ink droplets charged to the opposite polarity to the latent image potential adhere to areas where the latent image potential is high, and development is performed. The areas where the latent image potential is low pass through the mesh of the photoreceptor and are absorbed into the porous material layer 14. The image area of the photoreceptor 1 developed in this manner is rotated and transferred onto the transferred transfer material P by the transfer charger 18.

In the transfer process, residual ink on the photoreceptor that has not been transferred and ink that has been absorbed into the porous material layer 14 without contributing to development is dissolved in the solvent 61, thereby cleaning the surface of the photoreceptor. Further, the photoreceptor 1 is dried by a heater 63, and charged again to form a latent image.

Since there is no synchronizing signal from the photocell 12, when no pulse voltage is applied from the pulse voltage sources 25, 35, and 45, the ink droplet is not deflected and travels straight to the gutter 2.
3a, 23b, 33a-33b and 43a-43b.

In the transferred image, the same location of the original image in document 0 is finely divided into a plurality of color components, which are combined to form a color image. Its resolution is 5 trees per mm.

In addition, the pulse voltage source 25.3 of each inkjet array
Deflection electrode 22aφ32a and 4 by 4 and 45
By adjusting the voltage and phase or duty ratio of the pulse signal supplied to the pulse signal 2a, it is possible to obtain a copied image having a hue different from that of the original 0.

In this embodiment, 5 per 11 along the longitudinal direction of the photoreceptor l.
Although the wooden inkjet array is used, the deflection electrode 201a
-201b, 301a, 302b and 401am40
1b (each lined up in the direction perpendicular to the plane of the paper in the figure), between each deflection electrode 201a11201b, 301a-
If a high frequency voltage is applied between 302b and 401a and 401b to vibrate and deflect the ink droplets at high speed, dense development in the longitudinal direction can be achieved even if the density of the inkjet array is reduced, which is similar to the case of the embodiment. A similar color image can be obtained.

In addition to this embodiment, the developing means may be an on-demand inkjet method, a means using powder particles flying by an electric field, or the like.

Instead of the rotating filter 6, the document 0 may be irradiated with laser light pulses having different wavelength distributions. In short, it is sufficient to sequentially irradiate light with different wavelength distributions.

In addition, in the developing process, in order to synchronize with the latent image, the electrostatic potential on the surface of the photoreceptor is detected and the pulse voltage source is
Supply synchronization signals to 5-35 and 45 and enjoy. Similarly, a synchronization signal may be obtained by forming a magnetic pattern, an electrostatic pattern, an optical pattern, etc. for synchronization along the circumferential direction 0 at the end of the surface of the photoreceptor and detecting the pattern.

Furthermore, after cleaning the surface of the photoreceptor, it is also preferable to eliminate the static electricity using a photoreceptor static elimination means.

As detailed above, according to the present invention, a full-color image can be formed through the development process after passing through one latent image forming process, so the process speed is fast and only one transfer process is required. Therefore, there is no color shift and the reproducibility is good. A high-speed color image forming apparatus with good reproducibility can be realized.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of a color image forming apparatus to which the present invention is applied, and FIG. 2 is a detailed view of the main parts thereof. l is a photoreceptor, 2 is a porous material layer, 3 is a halogen lamp, 6
is a rotating filter, 12 is a photocell, 20/30-40 is an inkjet array, 21a/31as41a is a charging electrode, 22a*32ae42a is a deflection electrode, 25/35
-45 is a pulse voltage source, 0 is an original, and P is a transfer material.

Claims (1)

[Claims] (1) A document image is sequentially irradiated with light having a plurality of different wavelength distributions, and an electrostatic latent image corresponding to the color components of the document image is formed on the image carrier using reflected light, which is synchronized with the sequential irradiation. A color image forming apparatus characterized in that the electrostatic latent image is developed with a charged developer of a color corresponding to each color component at a time difference.