JP2591257B2 - Rotating mirror - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary mirror used for deflecting light in office equipment typified by printers, scanners and facsimiles using a light deflector, and in precision measuring instruments. It is.

2. Description of the Related Art In recent years, office equipment and precision measuring instruments that apply the property of light having a uniform phase represented by a laser have been frequently used. However, they are still generally expensive, large and heavy, and inexpensive, small and lightweight ones have been desired. In particular, the optical deflector and the device, which can be called the heart of these devices, were the key to reducing the cost, size, and weight of the device.

FIG. 7 shows an example of the configuration of a conventional office machine.
First, reference numeral 1 denotes a light source. Light emitted from the light source 1 passes through the collimating length 2, the modulator 3, and the cylinder lens 4, and reaches the rotary polygon mirror 5. The light is eventually reflected by the rotating polygon mirror 5 and transmitted through the fθ lens 6 and the cylinder lens 7 to irradiate the photosensitive drum 8. Note that the rotation position of the rotary polygon mirror 5 and the scanning start position are synchronized with each other using the photo sensor 10.

Here, the optical deflector consists of a rotating mirror.This rotating mirror is made by cutting it from a metal material to make it a basic shape as a rotating mirror, and then precisely polishing the reflecting surface of the rotating mirror. I was

In recent years, rotary polygon mirrors require a cutting step from a metal material and a precision polishing step of the reflecting surface. For each reflecting surface, the same work process is required, and each reflecting surface is required. Since it is necessary to finish the parts with the same precision as much as possible, there is a type in which a rotating mirror is formed by using a member formed of a polymer material or the like, and a reflecting surface is formed on the surface (Japanese Patent Application Laid-Open No.
No. 61-254920).

Problems to be Solved by the Invention However, in such a rotary polygon mirror, when the rotation axis of the rotation mirror and the axis of the incident light are slightly tilted due to vibration of equipment or the like, light is irradiated to the side surface of the rotation mirror, which is unnecessary. Was causing reflection.

The present invention provides a rotating mirror which has solved or improved these problems.

Means for Solving the Problems The rotating mirror of the present invention has an angle θ (0 degree <θ <
A reflective surface is provided on a surface inclined by 90 °), and the cross-sectional shape orthogonal to the optical axis becomes narrower in a direction away from the light source side.

Operation The rotating mirror of the present invention can prevent unnecessary reflection of light generated due to a deviation between the optical axis and the rotating axis due to vibration or the like due to such a configuration.

Embodiment Hereinafter, a rotating mirror according to an embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, reference numeral 11 denotes a rotating mirror. The rotating mirror 11 is formed by molding a polymer material or a sintered material represented by ABS resin, polycarbonate, or the like using a mold. Reference numeral 9 denotes a reflection surface, and the reflection surface 9 is formed by, for example, depositing or attaching a material that reflects light, such as aluminum. 12 is incident light, and the reflection surface 9 has an angle θ (0
(Θ <90 °), the incident light 12 is reflected in a direction corresponding to the inclination. The rotating mirror 11 is a rotating shaft 20
, And the direction of the reflected light 15 changes with the rotation.

Further, the present invention, when the diameter of the rotating mirror 11 near the light source is φC and the diameter of the rotating mirror 11 far from the light source is φD,
φD is smaller than φc. It is also possible to make φC smaller than the diameter of the entire light beam formed by the incident light 12 so that the reflection surface 9 of the rotating mirror 11 enters the entire area of the light beam of the incident light 12 as shown in FIG.

By adopting such a configuration, even if the rotation axis of the rotating mirror 11 and the axis of the incident light are slightly tilted, the light is not irradiated on the side surface of the rotating mirror 11, so there is no worry about unnecessary reflection of the light on the side surface of the rotating mirror. You don't have to.

Further, the surface of the rotating mirror may be subjected to processing such as silicon vapor deposition or rust prevention for protection.

Also, since the radius of rotation is small, the centrifugal force is small even at high rotation, and the deformation of the rotating mirror can be suppressed to a small value. As a result, the distortion of the reflecting surface is small, and the light is accurately reflected.

If the reflecting surface is flat, as shown in FIG.
If the incident light 12 from the rotation axis 20 of the reflecting surface 9 is shifted in reflection position like the incident light 12a or the incident light 12b, the path is different like the reflected light 15c or the reflected light 15d, and the photosensitive member 8
Therefore, the position of the incident light 12 needs to be accurate. On the other hand, as shown in FIG. 3, when the reflecting surface 9b is a curved surface, the rotation axis of the reflecting surface 9b is
The reflection position of incident light 12 from 20b is shifted like incident light 12a or incident light 12b, and even if the path is different like reflected light 15, reflected light 15a or reflected light 15b, the same position of photoconductor 8 is maintained. Image. Thereby, the margin of the positional accuracy of the incident light 12 is improved. Further, in this case, since the rotating mirror itself has an action of converging light, design and processing of a lens system such as a condenser lens used simultaneously with the rotating mirror becomes easy or unnecessary.

Further, as shown in FIGS. 5A, 5B and 5C, as an embodiment of the present invention, a part of the rotating mirror P, Q
May be formed in a shape from which is omitted. With these appropriate measures, the rotational moment of the rotating mirror with respect to the rotation axis becomes uniform. Accordingly, since there is no blurring of the rotating mirror, high-speed rotation can be easily realized, and the image quality can be improved. In this type of conventional apparatus, as shown in FIG. 8, a weight 18 of another part is retrofitted to the rotating mirror 11k as shown in FIG. Is unnecessary, and the manufacturing is easy.

Further, as shown in FIG. 6 (a), a cut may be provided at the light source side end of the cylinder in a direction opposite to the light source from the light source side end of the cylinder in parallel with the rotation axis. At this time, the member 19 may be inserted into the crack.

Further, as shown in FIG. 6B, a prism 19a may be inserted instead of the member 19. As a result, the resistance of air during rotation is reduced, so that windage loss and wind noise are reduced, the driving force for the rotating mirror is reduced, and high-speed rotation is enabled.

Further, as shown in FIG. 6 (c), a prism 19b may be used and the overall shape may be a cylinder. As a result, the shape change in the circumferential direction of rotation is reduced, and the resistance of air during rotation is reduced, so that the driving force for the rotating mirror can be reduced, and high-speed rotation can be performed. Further, if the prism 19b and the rotating mirror main body 11gb are made to have the same diameter and the same material and a reflecting surface is provided between the prism 19b and the rotating mirror main body 11gb, the rotation balance can be easily obtained. Also the incident light 12
When light is incident from the opposite direction, the reflection surface becomes two surfaces, so that the rotation time can be used more effectively than when one surface is used.

As shown in FIG. 1, the circumference of the reflecting surface 9 of the rotating mirror 11 may be provided with an anti-reflection coating 17, for example, alumite or a member, or a surface finish, for example, matting. Thereby, scattering of the reflected light generated when the incident light hits the reflecting surface 9 is prevented.

Effect of the Invention As is apparent from the above description, the rotating mirror according to the present invention has a diameter φC near the light source of the rotating mirror 11j,
If the diameter far from the light source is φD, then φC is φ
By making D smaller, even if the axis of rotation of the rotating mirror 11j and the axis of the incident light are slightly tilted, no light is irradiated to the side of the rotating mirror 11j. It is not necessary.

Further, in the present case, the turning radius can be smaller than that of the rotating polygon mirror, so that the size can be reduced. Furthermore, if a polymer material is used, it has the feature of being significantly lighter than a metal.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rotating mirror according to an embodiment of the present invention, and FIG.
FIG. 3 is a side view, FIGS. 3 and 4 are side views of another embodiment of the present invention, FIGS. 5 and 6 are configuration diagrams of another embodiment, and FIG. 7 is a configuration diagram of a conventional apparatus. FIG. 8 is a perspective view showing an example of the main part. 9: reflection surface, 11: rotating mirror, 12: incident light, 20: rotation axis.

Claims (7)

(57) [Claims] 1. A reflecting mirror is provided on a surface inclined by an angle θ (0 ° <θ <90 °) with respect to a rotation axis, and a cross section orthogonal to the optical axis becomes narrower in a direction away from the light source side. And a rotating mirror. 2. The rotating mirror according to claim 1, wherein the surface of the reflecting surface is a curved surface. 3. The rotating mirror according to claim 1, wherein an outer shape of a cross section perpendicular to the rotation axis is not symmetrical with respect to the rotation axis. 4. The rotating mirror according to claim 1, wherein the reflecting surface of the rotating mirror enters the entire area of the light beam of the incident light. 5. The rotating mirror according to claim 1, wherein antireflection means for unnecessary light is provided around and around the reflecting surface of the rotating mirror. 6. A rotating mirror according to claim 1, wherein a protective film such as silicon dioxide is deposited on a reflection surface of the rotating mirror and a corrosion preventing process is applied to a side surface of the rotating mirror. 7. The rotating mirror according to claim 1, having a center of gravity on a rotating shaft.