JPH0254711B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a multicolor printing device with good light balance for mixed colors. Prior Art and Problems Figure 1 shows an overview of a conventional multicolor printing device. In the figure, 1 is a photosensitive drum with a photoconductor layer formed on its surface; 2, 3, and 4 are chargers; 5, 6, and 7 are optical systems;
8, 9, and 10 are developing devices, 11 is a transfer section, 12 is a fixing section, 13 is a static elimination lamp, and 14 is a cleaning brush. The operation of this device is as follows. That is, the photosensitive drum 1 is rotated in the clockwise direction indicated by the arrow, and the surface thereof is processed in the following steps.
First, a charger 2 uniformly charges the surface, and an optical system 5 including a laser, a polygon mirror, etc. performs scanning to form a latent image of printed dots at a predetermined position. This latent image is for developing into C (cyan) color. Thereafter, this latent image is developed into C color by a developing device 8. Next, after a charging process is performed by the charger 3, scanning is performed by the optical system 6 to form a latent image at a predetermined position. This latent image is for developing into M (magenta) color. Thereafter, this latent image is developed into M color by a developing device 9. Next, after a charging process is performed by the charger 4, scanning is performed by the optical system 7 to form a latent image at a predetermined position. This latent image is for developing into Y (yellow) color. After that, this latent image is transferred to the developing machine 1.
0 to develop Y color. Next, these images are transferred onto paper 20 by a transfer section 11, and the transferred images are fixed by a fixing section 12. After the transfer has been completed, the surface of the photosensitive drum 1 is destaticized by the static eliminating lamp 13 and then cleaned by the cleaning brush 14, thus completing one cycle of operation. By the way, in a color electrophotographic apparatus that performs development multiple times, a non-contact type developing machine is required to prevent the developed toner from getting mixed into the developing machine for other colors. The degree of freedom in coloring is reduced, and it is difficult to achieve a good color balance when mixing colors, and black cannot be obtained by mixing C, M, and Y colors. In addition, as a means to solve this problem, C,
Attempts have also been made to install a developing machine with BK (black) color toner in addition to M and Y to perform four exposures, but this has the disadvantage of increasing the size of the device and slowing down the processing speed. are doing. Purpose of the Invention The present invention is intended to solve the various drawbacks mentioned above, and it is an object of the present invention to provide a multicolor printing device that can adjust the color balance of mixed colors without increasing the size of the device or reducing processing speed. The purpose is Structure of the Invention The present invention provides a multicolor printing device equipped with a plurality of developing machines that develop each latent image formed in the form of a set of printing dots on a photoconductor by scanning with a plurality of optical systems into different colors. A printing dot diameter changing means is provided in the middle of the optical path of each optical system, and the printing dot diameter changing means changes the printing dot diameter of each optical system depending on the type of color mixture to adjust the color balance of the mixture. We are trying to achieve the above objectives. Embodiments of the Invention Hereinafter, embodiments of the invention will be described with reference to FIGS. 2 and 3. FIG. 2 is a perspective view showing how to form a latent image by an optical system 21 to which the present invention is applied. The optical system 21 includes a laser 22, a beam compressor 23, a modulator 24, a beam expander 25, It includes a prism box 26, a cylindrical lens 27, a polygon mirror 29 driven by a mirror motor 28, a toroidal lens 30, and a double spherical lens 31, which are the characteristics of the invention. The beam emitted from the laser 22 enters the polygon mirror 29 and is reflected as shown by the double dotted line in the figure, and is driven by the drum motor 32 to the deceleration mechanism 33.
A latent image is formed by scanning the photoconductor layer on the surface of the photosensitive drum 1 rotated through the photosensitive drum 1 . In the present invention, the prism box 26 is provided between the laser 22 and the polygon mirror 29. This prism box 26 includes two prisms 34 and 34 for changing the beam diameter (print dot diameter) during scanning, as shown by solid lines and chain lines in FIG.
35, and is driven by a solenoid 36 to move forward and backward across the optical path in the direction shown by the arrow in FIG. 2 (perpendicular to the plane of the paper in FIG. 3). When the prism box 26 driven by the solenoid 36 is positioned above in FIG. 2, the prism 34 is positioned on the optical path, and when the prism box 26 is positioned below in FIG. 2, the prism 35 is positioned on the optical path. is positioned. Therefore, the print dot diameter changes when the prism 34 is positioned on the optical path and when the prism 35 is positioned on the optical path. This change in the print dot diameter is caused by a shift in the optical axes of the beams that enter in the direction of the arrow and exit from each prism in the same direction. Printing dot diameter changing means consisting of a prism box, solenoid, etc. that has such an effect is as follows:
It is provided in each optical system of a color electrophotographic apparatus. Therefore, by using this print dot diameter changing means, it is possible to adjust the color balance of the mixed colors by changing the print dot diameter of each optical system depending on the type of color mixture. The following table shows how to select the printing dot diameter when you want to make a certain color stronger to improve the color balance.

[Table] As shown in the table above, if you want to make the blue color stronger when mixing, increase the print dot diameter of the latent image forming optical system for C and M colors and reduce the print dot diameter of the Y color optical system. If you want to make the green color stronger, increase the print dot diameter for C and Y colors and reduce the print dot diameter for Y color, and if you want to make the red color stronger, increase the print dot diameter for M and Y colors and use C. All you have to do is make the diameter of the color printing dots smaller. It is also possible to obtain black by mixing C, M, and Y colors. Effects of the Invention As described above, according to the present invention, the printing dot diameters of each optical system can be changed, so color balance can be achieved by appropriately combining these diameters depending on the type of color mixture. It is possible to arrange the Furthermore, since there is no need to provide a developing machine with BK color toner and perform four exposures, it is possible to downsize the device and improve processing speed.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional multicolor printing device, Figs. 2 and 3 show an embodiment of the multicolor printing device according to the present invention, and Fig. 2 shows a procedure for forming a latent image using an optical system. The perspective view shown in FIG. 3 is a shape diagram of a prism provided in a prism box. In the figure, 1 is a photosensitive drum, 20 is paper, 21 is an optical system, 26 is a prism box, 34 and 35 are prisms, and 36 is a solenoid.

Claims (1)

[Claims] In a multicolor printing device equipped with a plurality of developing machines that develop a latent image formed in the form of a set of printing dots on a photoconductor in the form of a set of printing dots by scanning of a plurality of optical systems into different colors, there is a . A multicolor printing device, characterized in that a printing dot diameter changing means is provided for adjusting the color balance of the mixed colors by changing the diameter of the printing dots produced by each of the optical systems according to the type of color mixture.