JPS5953866A - Multicolor printer - Google Patents

Abstract

PURPOSE:To equalize optical distance of each color, synchronize scans with one another, and exposing respective colors at a specific position at the same time, and to simplify the structure by positioning a photosensitive drum and a reflecting surface at focuses of an ellipse, and performing the exposure of every color through a polygon mirror. CONSTITUTION:The center point of the photosensitive drum is positioned at one focus of the ellipse 16 and the reflecting surface of the polygon mirror 15 is set at the other focus. Then, three mirrors 17a, 17b, and 17c are provided on the ellipse. Laser beams emitted from three laser generators 13a, 13b, and 13c pass through modulators 14a, 14b, and 14c and are reflected by mirrors 15, 17a, 17b, and 17c to be exposed to the exposure parts (a), (b), and (c) of the drum 11. Latent images formed on the drum 1 in respective colors are color-developed by color developing devices 2a, 2b, and 2c. The optical paths from the mirror 15 to the drum 1 through the mirrors 17a, 17b, and 17c are equal in length.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an electrophotographic multicolor printer, and in particular to an improvement in an optical scanning mechanism for forming a latent image on a photosensitive drum thereof. be.

(2) Background of the technology In an electrophotographic multicolor printer, multiple light sources such as lasers corresponding to the number of colors are scanned at different positions on the photosensitive drum via a scanning polygon mirror (rotating polygon mirror). A latent image corresponding to each color is formed by irradiating the surface with light 7, and development is performed using toner of each color in a developing section provided after each light irradiation section. In this case, if the scanning of the photosensitive drum surface by the laser light source corresponding to each color is not perfectly synchronized, when the toner image is transferred to the printing paper, the images, characters, etc. of each color will not be formed in the desired position, and will be misaligned. The color scheme is related to the relationship. In addition, there is a demand for such multicolor printers to be smaller and more economical.

(3) Prior Art and Problems The configuration of a conventional multicolor printer is shown in FIG. Three latent image forming portions a, b, and e on the photosensitive drum 1 are irradiated with laser light for forming latent images corresponding to images of different colors of λ. Immediately after each latent image forming section a, b, c is a developing section 2a having toner of a different color.

2b and 2c are provided. Laser light is emitted from three laser generators 3a, 3b, and 3c corresponding to each latent image forming portion a+b+C, and a laser beam is emitted from a modulator 4a.

4b and 4c modulate each separate polygon mirror 5a,
Each latent image forming portion a is reflected by V by 5b and 5c.

A latent image is formed by scanning b and c. In a multi-color printer having such a configuration, the laser beams from the laser generators 3a, 3b, 3c for forming latent images of different colors are transmitted to separate scanning polygon mirrors 5a.

5b, 5c onto the photosensitive drum 1, the latent image forming portions a, b on the photosensitive drum 1 may be affected due to uneven rotation of each polygon mirror 5a, 5b, 5c or lack of accuracy of the reflecting surface. , c may not be perfectly synchronized and the timing may be off, making it impossible to print with the desired color scheme.

Furthermore, in a multicolor printer having such a configuration, the polygon mirror is relatively large and expensive, so the device is large and expensive.

(4) Purpose of the Invention The present invention has been developed in view of the above-mentioned drawbacks of the prior art. purpose.

(5) Structure of the Invention In order to achieve this object, the present invention provides a multi-color printer that irradiates light from a light source through a scanning polygon mirror onto a plurality of positions on a photosensitive drum to form a latent image corresponding to each color. , a plurality of mirrors are provided on an ellipse with one focal point at the center of the photosensitive drum, and a common polygon is used to scan each irradiation position so that the reflecting surface is located on the other focal point of the ellipse. All the mirrors are arranged, and a plurality of light sources are arranged so as to illuminate different positions on the photosensitive drum through the common polygon mirror and one mirror on the elliptical surface.

(6) Embodiment of the Invention FIG. 2 is a block diagram of a multi-color printer according to the invention. Three latent image forming portions a on the photosensitive drum 11.

Developing sections 12 each having toner of a different color immediately after b and c
a, 12b, and 12c are provided. Three mirrors 17 are arranged on an ellipse 16 with one focal point F at the center of the photosensitive drum 11.
a, 17b, and 17a are provided.

A common polygon mirror 15 for irradiating each latent image forming portion a, b, and c is arranged so that the scanning reflecting surface is located at another focal point F' of this t'1 circle 16.

This common polygon mirror 15 and each mirror 17 m + 17 b + provided along the ellipse 16
or each latent image forming portion a on the photosensitive drum 11 via 17c.
, b, and 1'tc, and associated modulators 14a, 14b, and 14c are respectively arranged at appropriate locations. Each laser generator 13a.

The laser beams emitted from 13b and 13c are reflected by a common polygon mirror 15, pass through separate optical paths, and are reflected by one mirror 17a, 17b, or 17c on an ellipse 16, and are reflected at each latent image forming portion a, b, Scan c. Each mirror 17a,
The laser beams reflected by 17b and 17c are directed to the photosensitive drum 11.
toward the center (focal point F).

(7) Effects of the invention In a multicolor printer configured as described above, a scanning light beam for forming latent images corresponding to each different color is scanned using a common polygon mirror, and the photosensitive drum is A polygon mirror is installed on an ellipse whose focal point is the center and the reflective surface of the polygon mirror, so that the reflection direction of the light beam from the polygon mirror is directed toward the center of the photosensitive drum, and the original beam from each light beam generator is transferred to the polygon mirror. The light is reflected by one mirror on the ellipse and illuminates the photosensitive drum surface. Therefore, the distances from the reflective surface of the polygon mirror to each irradiation position on the photosensitive drum are all equal, and since the polygon mirror is common, the synchronization of scanning by each party beam is completely consistent, and images of desired colors are separated. The image is printed at a predetermined position relative to the IK color of the image. Furthermore, since only one polygon mirror is required, the structure is simple and compact, and the cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional multi-color printer, and FIG. 2 is a block diagram of a multi-color printer according to the present invention. 1, 11...Photosensitive drum, 3a*3b
+ 3 c +13 a e 13 b + 13 c
=・Laser generator, 5a. 5b, 5c, 15...polygon mirror, F, F'...
・Focus, 16...Ellipse, 17 a, 17 b
, 17c-Miller. Patent applicant Fujitsu Limited Patent agent Akira Yoiki Patent attorney Kazuyuki Nishidate Patent attorney Yukio Uchida Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. In a multi-color printer that irradiates light from a light source via a scanning polygon mirror onto multiple positions on a photosensitive drum to form a latent image corresponding to each color, a latent image is formed on an ellipse with the center of the photosensitive drum as one focal point. A common polygon mirror for scanning each irradiation position is arranged so that the reflecting surface is located on another focal point of the ellipse, and the common polygon mirror and the elliptical surface are provided with a plurality of mirrors. A multi-color printer 3 characterized in that a plurality of light sources are arranged so as to illuminate different positions on the photosensitive drum through each one of the upper mirrors.
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