JPH0234364B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] This invention relates to at least one method of optically reading information recorded on a track on a recording medium or optically recording information on a recording medium. The present invention relates to an improvement in a deflection mirror device used in an optical information recording/reproducing device having either one of the functions.

[Prior Art] Conventionally, as this type of device, for example, a video disk player, a digital audio disk player, etc. are known, and the disks used in this type of optical information recording and reproducing device are generally:
The track pitch is about 1 μm to 2 μm, and the track width is about 0.5 μm. In order to record or play back on a disk with tracks formed in such a high density, it is necessary to focus the light beam from the light source to a diameter of about 1 μm to 2 μm. Tracking errors due to symmetrical positional deviations with respect to the spots must be kept within the submicron range. A so-called deflection mirror device is used for this purpose.

1 to 3 show a conventional deflection mirror device, FIG. 1 is a front view, FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 3 is a cross-sectional view of FIG. , 1 is a base holder that forms the basis of the device, 2
Permanent magnets a and 2b are mounted symmetrically on both outer sides of the base holder 1, and 3 is a cylindrical coil arranged inside the permanent magnets 2a and 2b. 4
is a coil holder around which the above-mentioned 3 is wound; 5 is a mirror adhered to the front of the coil holder 4 in a superimposed state; 6 is provided at the center of the holder 1, and its tip protrudes at a position midway between the permanent magnets 2a and 2b; The supporting rod 7 is the coil holder 4 and the supporting rod 6.
A is a support made of an elastic material such as rubber, which is interposed between the front mirror 5 and rotatably supports the front mirror 5 in a fixed direction.

In the above configuration, since the magnetic circuit is configured by the permanent magnets 2a and 2b, when a current is passed through the coil 3, the support rod shaft in the support body 7 in FIG. The movable portion A rotates in the direction of the arrow in the figure around an axis passing through a certain point on the X-axis and perpendicular to the plane of the paper. The rotation of the movable part A causes the mirror 5 to rotate and the position of the optical spot on the disk to be controlled.

[Problems to be Solved by the Invention] Since the conventional deflection mirror device is configured as described above, the center of rotation of the movable portion A is determined by the tilt of the deflection mirror device, the position of the center of gravity of the movable portion A, and the coil 3. Determined by the drive position and the shape of the support 7, etc.
It is difficult to fix the center of rotation regardless of the tilt angle of the deflection mirror device, and when the attitude of the deflection mirror device is changed, the tilt of the mirror device tends to shift due to the change in the center of gravity of this device. This has the disadvantage that the position of the reflected beam shifts on the disk, or that the position of the deflection mirror device is always unstable due to external shocks, which in turn increases the tracking error. There was a problem.

This invention was made to solve the above-mentioned problems, and it is possible to set the rotation center of the movable part at a predetermined value, so that the rotation direction is stable and does not shift even when subjected to external shocks. The purpose is to obtain a highly accurate deflection mirror device.

[Means for Solving the Problems] A deflection mirror device according to the present invention includes a coil holder that is pivotally supported on a support rod provided at the center of a base holder by a shaft along the axis of rotation of a movable part, A pair of elastic correction springs are stretched between both sides of the rotating side of the movable part and the inside of the coil holder.

[Function] In the deflection mirror device of the present invention, when a current is passed through the coil, the mirror rotates around the shaft by an angle corresponding to the current value, and when the coil current disappears, the mirror is moved to a predetermined angular position by the elastic correction spring. to return to.

[Embodiment] An embodiment of the deflection mirror device of the present invention will be described below. FIG. 4 is a side sectional view showing an embodiment of the present invention, and FIG. 5 is a plan sectional view thereof. In the figure, 1 is a base holder, 2a, 2b are permanent magnets, 3 is a coil, 5 is a mirror, 8 is a coil holder having a protrusion 8a on the side opposite to the central mirror;
9 is a movable part, 9 is a support rod that is provided at the center of the base holder 1 and has a flange 9a and a U-shaped part 9b at the tip; 10 is a movable part A that rotatably connects the coil holder 8 and the support rod 9; Synthetic resin shafts 11a, 11b are pivotally supported by the protruding portion 8a and the U-shaped portion 9b in order to rotate around the Zb-Zb axis.
are stretched between the inside of the coil holder 8 and both sides of the rotating side of the support flange 9a, and the front mirror 5
This is a pair of elastic correction springs for elastically holding the image in a direction perpendicular to the illustrated X-ray at all times.

Next, the operation of this embodiment will be explained. That is, since a magnetic circuit is constituted by the permanent magnets 2a and 2b, when a current is passed through the coil 3, the shaft 10, that is, the center axis of rotation, changes depending on the current value.
The mirror 5 rotates together with the movable part A around Zb and Zb. When the current in the coil 3 disappears, the mirror 5 is returned to a predetermined angular position perpendicular to the X-ray by the elastic correction springs 11a and 11b. At this time, the movable part A is
No matter what angle the base holder 1 is attached to, it rotates in a predetermined direction without being affected by gravity and without being changed by external impact. Further, changes in the amount of rotation of the base holder 1 depending on the mounting angle and fluctuations in the return position of the mirror 5 can be dealt with by arbitrarily selecting the spring constants of the elastic correction springs 11a and 11b.

[Effects of the Invention] As described above, according to the present invention, the coil holder is pivotally supported on the support rod provided at the center of the base holder by a shaft along the axis of rotation of the movable portion, and the movable portion of the support rod is Since a pair of elastic correction springs are stretched between both sides of the rotating side and the inside of the coil holder, the center of rotation of the movable part is determined, and the direction of rotation can be prevented even by external shocks. By arbitrarily selecting the spring constant of the elastic correction spring, the rotational characteristics and return angle position of the movable part can be set as desired, and a stable and highly accurate deflection mirror device can be obtained.

[Brief explanation of drawings]

Figure 1 is a front view of a conventional deflection mirror device, Figure 2 is a front view of a conventional deflection mirror device;
1, FIG. 3 is a sectional view taken from FIG. 1, FIG. 4 is a side sectional view showing an embodiment of the present invention, and FIG. 5 is a plan sectional view thereof. In the figure, 1 is a base holder, 2a, 2b
3 is a permanent magnet, 3 is a coil, 5 is a mirror, 8 is a coil holder, A is a movable part, 9 is a support rod, 10 is a shaft, and 11a and 11b are elastic correction springs.
The same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A movable part consisting of a coil holder, a coil wound around it, and a mirror attached to the front of these is rotatably attached to the tip of a support rod provided at the center of the base holder, and this movable part is In a deflection mirror device that is located between permanent magnets provided on the base holder and configured to rotate the mirror at a desired angle by driving current to the permanent magnets and the coil, the coil holder is attached to the support rod. The movable part is pivotally supported by a shaft along the axis of rotation of the movable part, and a pair of elastic correction springs are stretched between both sides of the support rod on the movable part rotation side and the inside of the coil holder. Deflection mirror device.