JP2530813Y2 - Multi-color printing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a multicolor printing apparatus, and more particularly to a multicolor printing apparatus in an electrophotographic recording system such as an electrostatic printer laser printer.

(2) Background of the Technology As is well known, almost all colors and degrees of light and shade can be almost reproduced by an appropriate combination of three primary colors: red, green, blue or their complementary colors: cyan, magenta, and yellow. In a multicolor printing system in an electrophotographic recording system including charging, latent image formation, development, and transfer cleaning processes, a developer using the above three primary colors or their complementary colors is used.

(3) Conventional Techniques and Problems As a multicolor printing method in the electrophotographic system, a method of performing multicolor printing by repeating a plurality of sets of latent images using a conventional latent image and development as a set, and a potential of the latent image. There is a multicolor printing method in which development is performed by changing the color according to the potential by changing the color.

FIG. 1 is a schematic view showing one embodiment of a conventional multicolor printing system in which a latent image and development are repeated. In FIG. 1, the surface of a recording drum 1 in which a photoconductive film 1b is formed on a conductive support 1a is uniformly charged by a corona charger 2, and then a laser light source 3 causes the developed color to correspond to cyan. Forms a latent image,
Next, the latent image forming portion is developed by a developing machine 4 using a cyan developer (cyan developing toner). Subsequently, a latent image whose development color corresponds to yellow is formed by the laser light source 5 and then developed by the developing machine 6 with a yellow developer. Similarly, a latent image whose developing color corresponds to magenta is formed by the laser light source 7 and then developed by the developing device 8 with a magenta developer. In this way, the cyan latent image, the yellow latent image and the magenta latent image are respectively developed, and then the corona discharger 9
Thus, the toner image in each developer is transferred to the plain paper 10.
Thereafter, the residual toner on the recording drum 1 is removed by the fur brush 11, and the recording drum 1 repeats the above process again to perform continuous printing. However, according to the conventional method as described above, there is a problem of color mixing between different colors as can be seen from FIGS. 2a to 2c showing a potential change in a printing process. That is, after uniform charging as shown in FIG. 2A, the cyan developing toner 12a is supplied to the latent image portion 12 for the cyan developer, and then, as shown in FIG. 2B, the latent image portion 13 for the yellow developer. The yellow developing toner 13a is supplied at a specified potential. However, as shown in FIG. 2C, at the time of this supply of yellow, the excess yellow developing toner 13b is changed to a part of the cyan developing toner 12a already supplied into the cyan-specific latent image portion 12 and its position. May be interchanged. As a result, a normal color is not developed at a target position, and color mixing is caused.

As a multicolor printing method other than the above, there is a method of performing development in which the potential of a latent image is changed and the color is changed in accordance with the potential, but in this method, control of the potential of the latent image is difficult,
Therefore, there are drawbacks such as difficulty in realizing two or more colors.

(4) Object of the Invention In view of the above drawbacks, the present invention has an object to provide a vivid multicolor printing apparatus which has no color mixture for a color image and has a high resolution for a black image. .

(5) Configuration of the Invention The above-described object is to form a plurality of image formations for forming an electrostatic latent image for each color at an image formation target position among the separate positions set for each color on the image carrier. Means, and a plurality of developing means for developing the electrostatic latent images of the respective colors using toners of different colors, respectively, wherein each of the developing means is formed at the image forming target position on the image carrier. In order to develop the electrostatic latent images for each of the colors, a plate-like member having an opening only at a position corresponding to a separate position set for each of the colors is provided between the plate and the image carrier. This is achieved by a multicolor printing device characterized by comprising:

(6) Embodiment of the Invention Hereinafter, an embodiment of the invention will be described with reference to the drawings.

FIG. 3 is a schematic view showing one embodiment of the multicolor printing apparatus according to the present invention. The surface of the recording drum 1 having the photoconductive film 1b formed on the conductive support 1a is uniformly charged to +800 V using the corona charger 2, and then an electrostatic latent image is formed by the laser light source 3a. FIG. 4 is an explanatory view of the method of forming the electrostatic latent image. The dot diameter of the latent image for displaying each color is 50 μm, and the latent image pitch is 100 μm. In this embodiment, latent images corresponding to three development colors of cyan (), yellow (), and magenta () are arranged as shown in FIG. The latent images in the first latent image portion 30 corresponding to the three colors of cyan, yellow, and magenta are simultaneously formed by one scanning of the laser beam. Around the recording drum 1, cyan, yellow, and magenta developers 4a, 6a, and 8a are provided in two-component developing machines 4, 6, and 8 using developers of three primary colors of cyan, yellow, and magenta, respectively. . Here, the cyan developing machine 4 will be described as an example. FIG. 5 is a schematic sectional view of a cyan developing machine. The developing machine has a particle size of 100 to 200 μm
A stirring magnetic roller 15 for stirring and frictionally charging a two-component developer composed of a carrier 20 which is an iron powder of about a degree and a toner 21 which is a fine particle colored in cyan, and for developing an electrostatic latent image And a slit plate 18 for supplying developer only to the cyan latent image position, and a blade 19 for removing residual developer. . FIG. 6 shows the configuration of the aforementioned slit. The slit length 20mm, width 50μ
m, a pitch interval of 300 μm, and a thickness of 20 μm. By adjusting the position of the slit plate 18 to the position of the cyan latent image defined in advance, only the cyan latent image is developed with the cyan developing toner. Similarly, the slit plates in the remaining two-color, yellow and magenta developing machines are provided with slits at portions limited to the positions corresponding to the respective colors as described in FIG. 4 so that only the yellow latent image and the magenta latent image are respectively provided. Is developed. If the slit widths corresponding to the respective colors do not overlap within the pitch interval of the slits, a good color image can be obtained without mixing the colors. In this embodiment, a latent image is formed at a resolution of 10 lines / mm using a laser light source and developed with a high-resistance magnetic toner in order to realize a clearer black. Next, these multicolor toner images are transferred to plain paper 10 by corona discharger 9. The residual toner on the recording drum 1 is removed by a fur brush 11 by a known method, and the recording drum repeats the above-described multicolor printing process again to perform continuous printing. One embodiment of the potential change in the above-described printing process is shown in FIGS. 7A to 7G. After the surface of the recording drum 1 is charged to +800 V, a first latent image portion is formed at a position limited to each color of cyan (), yellow (), and magenta (). A latent image potential of +50 V is obtained for each magenta. Next, when the image is developed by the cyan developing machine 4, as shown in FIG. 7C, the cyan () developing toner is adhered only to a limited position when forming the latent image. The surface potential on the toner layer at this time is about
500V. Next, in the same manner, the toner is developed by the yellow developing device 6 and the yellow developing toner is attached next to the cyan developing toner as shown in FIG. 7D, and gradually yellow () as shown in FIG. 7E.
The magenta () developing toner is attached next to the developing toner. The surface potential on the developed toner layer of each color is about 500 V as in the case of cyan. The developing bias Vb of the developing machine is 60
It was set to 0V. Next, after forming the second latent image portion for black (FIG. 7F), the latent image potential becomes 50V. For forming the second latent image, a high-resistance-component magnetic toner is used. As shown in FIG. 8, the high resistance-component magnetic toner has a characteristic that the development starts when the threshold value exceeds 500V. For this purpose, the developing bias of the high resistance component brush developing machine was set to 800V.
Then, the black toner of one component does not adhere to the cyan, yellow, and magenta toner layers, and only the latent image of the black toner is developed to obtain a potential of 300 V at this time (FIG. 7G).

(7) Effects of the present invention As is clear from the above description, according to the present invention, charging,
Multicolor printing system consisting of latent image formation, development, transfer, and cleaning processes, where the latent image and development position for each of a plurality of colors are correspondingly limited, so that there is no color mixing of color images, and black and vivid multicolor A printing device can be obtained.

[Brief description of the drawings]

FIG. 1 shows one embodiment of a conventional multi-color printing system, FIG. 2A is a schematic diagram for explaining color mixing, and FIG.
FIG. 1 shows an embodiment of a multicolor printing apparatus according to the present invention,
FIG. 5 is a schematic view for explaining a latent image forming method according to the present invention, FIG. 5 is a schematic view of a cyan developing machine according to the present invention, and FIG. 7A to 7G are schematic perspective views of a slit which is an embodiment as a means for associating and limiting the relationship between the potential change in the printing process according to the present invention and FIG. FIG. 4 is a diagram illustrating characteristics of a resistance-component magnetic toner. DESCRIPTION OF SYMBOLS 1 ... Recording drum, 1a ... Conductive support, 1b ... Photoconductive film, 2 ... Corona charger, 3, 5, 7 ... Laser light source, 4, 4 '
…… Developer for cyan, 4a …… Developer for cyan, 6,6 '…
… Developer for yellow, 6a …… Developer for yellow, 8,8 '
…… Developer for magenta, 8a …… Developer for magenta,
9 corona discharger, 10 plain paper, 11 fur brush, 12 latent image portion for cyan developer, 12a cyan developed toner, 13 latent image portion for yellow developer, 13a
... Yellow developing toner, 14 black developing machine, 15 magnetic stirring roller, 16 magnetic developing roller, 17 blade for aligning developer, 18 cyan developer latent A slit plate for supplying only to the image position, 19 a blade for removing residual developer, 20 a carrier, 21
……toner.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Yamada 1015 Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-49-82345 (JP, A) Full-fledged 50-33047 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] A plurality of image forming means for forming an electrostatic latent image for each color at an image forming target position among the discrete positions set for each color on an image carrier; A plurality of developing means for developing each of the electrostatic latent images using toners of different colors, wherein each of the developing means is provided for each of the colors formed at the image formation target positions on the image carrier. In order to develop an electrostatic latent image, a plate-like member having an opening only at a position corresponding to a separate position set for each color is provided between the image carrier and the plate member. Multicolor printing device.