JPS62189421A - Galvanomirror - Google Patents

Abstract

PURPOSE:To obtain a galvanomirror for scarcely generating the deviation of an optical axis caused by the attitude error of a reflecting means, by providing a reflecting means, and a rotary means for turning the reflecting means around a rotary axis which intersects its reflecting surface. CONSTITUTION:A reflecting means 1 has a rotary axis for intersecting its reflecting surface at 45 deg., a rotary means 2 turns the reflecting means 1 centering around its rotary axis, and an elastic member 3 works so as to hold the reflecting means 1 in a reference position. When the reflecting means 1 is turned in the direction as indicated with an arrow, an optical axis is inclined by thetadegrees in the same direction by its geometrical quality. That is to say, according to this constitution, the turning of the optical axis which follows the turning of the reflecting means 1 becomes half or a conventional example, and according, an optical axis shift which is generated by an attitude error DELTAtheta of the reflecting means 1 also become DELTAtheta being a half of the conventional example. In this way, the deviation of a reference optical axis, which is generated by the attitude error of the reflecting means 1 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a galvanometer mirror used in a tracking actuator, tangential actuator, etc. of an optical disk device.

2. Description of the Related Art As shown in FIG. 5, a conventional galvano mirror includes a reflecting means 1, a rotating means 2 for rotating the reflecting means 1 around a rotating axis included in its reflecting surface, and It is constructed with an elastic member 3 for maintaining the posture of the means 1.

Problems to be Solved by the Invention However, the above configuration has the following problems. That is, as shown in FIG. 2(a), the reflecting means 1
The optical axis of the reflected light beam is deflected by 2θ with the rotation θ, but this tends to cause an error in the center of the optical axis. In the configuration shown in FIG. 6, the reference position of the reflecting means 1 (the position of the reflecting means 1 when the rotating means 2 is not substantially acting) is determined by the equilibrium point of the elastic member 3. However, in general, the material forming the elastic member has hysteresis due to its viscosity and fatigue, and furthermore, thermal expansion due to changes in environmental temperature, etc., so the position of the equilibrium point will have a considerable amount of error. At this time, if the attitude error (deviation from the reference position) of the reflecting means 1 is Δθ, then the actual deviation of the optical axis is 2Δθ.

In view of the above problems, it is an object of the present invention to provide a galvanometer mirror in which the optical axis shift due to the attitude error of the reflecting means 1 is smaller than that of the conventional mirror.

Means for Solving the Problems In order to solve the above problems, the galvanomirror according to the present invention includes a reflecting means and a rotating means for rotating the reflecting means around a rotating axis intersecting the reflecting surface thereof. .

Operation With the above configuration, the rotation of the optical axis due to the rotation θ of the reflecting means becomes θ, and therefore the deviation of the optical axis due to the attitude error ′ of the reflecting means becomes half of that of the conventional system.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing one embodiment of the present invention.

In FIG. 1, 1 is a reflecting means, 2 is a rotating means, and 3 is an elastic member. The reflecting means 1 has a rotating wheel that intersects its reflecting surface at 45 degrees, and the rotating means 2 rotates the reflecting means 1 about its rotating axis. The elastic member 3 acts to hold the reflecting means 1 in the reference position. In FIG. 1, the elastic member 3 is shown to maintain the posture of the reflecting means 1 with respect to the outer frame of the rotating means 2, but this shape is not limited.

The effect of this configuration is shown in FIG. 2(b). Figure 2 (b
) is a view of the present embodiment FEed in FIG. 1 from the direction A. When the reflecting means 1 is rotated in the direction of the arrow in the figure, the optical axis is tilted θ in the same direction due to geometrical optics. That is, in this configuration, the rotation of the optical axis due to the rotation of the reflecting means 1 is half that of the conventional example. Therefore, the optical axis shift caused by the attitude error Δθ of the reflecting means 1 is also half that of the conventional example.

As described above, according to this embodiment, the deviation of the reference optical axis caused by the attitude error of the reflecting means 1 can be reduced.

Next, other embodiments of the present invention will be described. FIG. 3 is a perspective view showing a second embodiment of the invention. In FIG. 3, 1.2.3 are the same components as shown in FIG. 4 is a counterbalance to the reflecting means 1, and is coupled to the reflecting means 1 by a rigid body. By doing so, the rigid body composed of the reflection means 1 and the counterbalance 4 can be driven around its center of gravity.

As a result, it is possible to prevent unnecessary resonance caused by mass imbalance or the like, or optical axis deviation associated with it.

FIG. 4 is a perspective view showing a third embodiment of the present invention. In FIG. 4, the rotating means includes the magnetic field generating means 2a and the coil 2.
The coil 2b is provided on the counterbalance 4. A coil and a magnetic field generating means are also provided on the opposite side of the counterbalance 4 to drive the counterbalance 4 rotationally symmetrically with respect to the rotation axis.

The latter coil and magnetic field generating means are not clearly shown in the figure. The reflecting means 1 is provided in a counterbalance 4, and the counterbalance 4 is provided with a window for passing light. The elastic members are constituted by elastic support members 3a to 3h. These elastic support members act not only to obtain a reference for the direction of rotation of the reflecting means 1, but also to obtain the axis of rotation. That is, if the vicinity of the center of gravity of the counterbalance 4 is driven rotationally symmetrically, only moment force is applied to the counterbalance 4. If all the elastic support members 3a to 3h have the same elasticity, they will expand and contract equally, and as a result, the rotating wheel will be maintained. Let me clarify once again the purpose of Counterbalance 4. In this embodiment, the counterbalance 4 essentially functions as a lens barrel for holding the reflecting means 1, but its original purpose is to balance the mass of the rotating part as described in the second embodiment. It is for taking. If the mass is not balanced, even if a driving force is applied in a rotationally symmetrical direction, the reflection means 1 will not rotate correctly, but will undergo translational or torsional movement.The counterbalance 4 will cause the reflection means 1 and the coil to It is formed with a shape or mass distribution that balances the mass of the entire rotating body including 2b.

As described above, according to this embodiment, by balancing the mass of the entire rotating body, the rotating shaft of the reflecting means 1 can be held by the elastic support member.

Effects of the Invention According to the present invention, by including a reflecting means and a rotating means for rotating the reflecting means around a rotating axis that intersects with the reflecting surface of the reflecting means, the optical axis due to an attitude error of the reflecting means is It is possible to realize a galvanometer mirror with less deviation.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is an explanatory diagram comparing the effects of a conventional example and an embodiment of the present invention, and FIG. 3 is a perspective view showing a second embodiment of the present invention. FIG. 4 is a perspective view showing a third embodiment of the present invention; FIG.
The figure is a perspective view showing a conventional example. l... Reflection means, 2... Rotation means, 3
...Elastic member. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 ゝ, Figure 2 (6 lines 2θ (b) θ Figure 3? Figure 4 G

Claims (1)

[Claims] A galvanometer mirror comprising a reflecting means, a rotating means for rotating the reflecting means around a rotation axis intersecting the reflecting surface thereof, and an elastic member for elastically coupling the reflecting means and a suitable base material.