JPS5834425A - Optical scanner - Google Patents

Abstract

PURPOSE:To obtain a miniature and highly accurate optical scanner which has simple constitution and can be easily produced, by providing a lens or an aspherical mirror to guide in a prescribed direction the light which goes in and comes out of a rotor consisting of a light-transmittable parallel plate or a square pillar. CONSTITUTION:The light beam stopped down is made incident to a rotor 3 consisting of a light transmittable parallel plate or a square pillar along an optical axis 2. Thus the transmitted light is turned into the light beams parallel to the axis 2, and the distance h1 to the axis 2 depends on the rotating angle theta1 of the rotor 3. The beam radiated from the rotor 3 is made incident to an angle compensating lens 4 and then radiated again at an angle theta2 to be projected on the surface of a drum through a ftheta lens 5. The distance h2 of the projected light beam to the axis 2 is proportional to the angle theta1. Thus an equi-speed scan is possible by giving the equi-speed rotation to the rotor 3. In such a way, a miniature and highly accurate optical scanner is obtained with a simple constitution and an easy production.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning device used in a laser printer or the like.

Galvano mirrors and rotating polygon mirrors have been used in conventional optical scanning devices such as laser printers. Optical scanning devices using galvano mirrors have oscillating galvano mirrors, which increases the viscosity of scanning, unstable performance, and limitations in increasing the scanning speed. On the other hand, an optical scanning device using a rotating polygon mirror has the disadvantage that the rotation axis of the polygon mirror and the optical axis are misaligned, resulting in a large device.Since there are many reflective surfaces, it is not easy to process. Problems such as the surface falling down are also likely to occur. Furthermore, since all of these conventional optical scanning devices utilize reflection of light, there is little freedom in arrangement when they are installed in a laser printer or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission type optical scanning device that is small in size, has high precision, has a simple configuration, and is easy to manufacture. In accordance with this purpose, a rotating body consisting of a translucent parallel plane plate or a square prism, and a lens or aspherical mirror that guides the light incident on the rotating body and emitted in a predetermined direction are used. A scanning device is provided.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, in front of the drone, which is placed on the same projection plane, on the light ffl+ 2, there is a rotating body 3 made of a translucent parallel plane plate or a square prism, and an angle correction lens 4. , Jθ lenses 5 are arranged at a predetermined interval. The angle correction lens 4 and the fθ lens 5 constitute a position correction lens. The rotating body 3 is rotated in a plane perpendicular to the projection plane 1 by means not shown.

When a light beam narrowed down to a sufficiently narrow beam by a means not shown in the figure is directed to the optical axis 2 and is incident on the rotating body 3, the rotating body 3 has a horizontal plane plate size of 1, which is a square prism.
The light after passing through becomes a ray parallel to the light tlQi 2, and the distance /i+ from the light 'l'l112 is the rotating body 3
The light ray emitted from the rotating body 3, which depends on the rotation angle 01 of
1Here, if θ2- is set to θ, then the distance from the optical axis 2 of the light beam projected onto the drum surface 1 through the fθ lens 5 will be 11.2 A2:
l: k'θ1. By rotating the rotating body 3 at a constant speed, the light beam emitted from the fθ lens 5 scans the tortoise surface 1-1- at a constant speed.

J4. used in the angle correction lens 4. An aspherical lens may be used instead of a surface lens. In place of the position correction lens consisting of the angle correction lens 4 and the 1θ lens 5, as shown in FIG.
can be used. Furthermore, instead of this aspherical lens 6, an aspherical mirror 7 may be used as shown in FIG. If the f'+ degree correction lens 4 is a 7 lindrical lens, the inclination of the surface of the rotating body 3 can be ignored. As long as they are parallel,
This is because it fully fulfills its function.

As described above, according to the present invention, there is no need to oscillate unlike a galvanometer mirror, and the rotating body only needs to be rotated at a constant speed, so the scanning accuracy is high and high-speed scanning is also possible. , it can be made significantly smaller than a rotating polygon mirror, has fewer surfaces, and is easier to process.Furthermore, since it is a transmission type,
There is no need to provide a reflective film, and there are advantages such as a high degree of freedom in layout. .

1 is a diagram showing the optical system of the optical scanning device according to the present invention, FIG. 2 is a diagram showing another optical system of the optical scanning device according to the present invention, and FIG. , is a diagram showing still another optical system of the optical scanning device according to the present invention.

1. Torano/surface, 2. Optical axis, 3. Rotating body,
-3= 4.Angle correction lens, 5-fθ lens, 6.Aspherical lens, 7.Aspherical mirror.

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Claims (1)

[Claims] An optical scanning device 9 that includes a rotating body made of a translucent parallel plane plate or a square prism, and a lens or non-J-shaped mirror that guides the light incident on the rotating body and emitted in a predetermined direction.゜