JPH0214011Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation support device for a galvanometer mirror used in an optical signal recording device or an optical signal reproducing device such as an optical video disk or audio disk.

As shown in Fig. 1, an optical disk has concave portions 2 on the surface of a disk 1 made of aluminum or the like, whose length and mutual spacing vary depending on the recorded signal, and whose upper surface has a reflectance of light. They are usually plated to increase the quality and coated entirely with transparent synthetic resin. The reading of signals from this optical disk is based on the fact that when the surface of the disk 1 is irradiated with light, the intensity of the reflected light changes due to the phase difference between the light reflected from the surface and the light reflected from the recess 2. I will use it to do this.

In this case, the signal is recorded spirally from the inner circumference to the outer circumference of the disk 1, and the recess 2
The length and spacing are 0.9 to 3.3 μm, the depth is 0.11 μm, the width is 0.6 μm, and the track pitching is 1.6 μm. The signal is then read out by focusing the light beam to a diameter of approximately 1 μm using an objective lens, irradiating this focused light beam onto the concave portion of disk 1, and detecting the reflected light with a detection device. Become.

In order to perform stable recording and playback, a focus servo mechanism is required to adjust the objective lens to focus on the disk 1, and a tracking servo mechanism is required to follow the light beam spot so that it does not deviate from the recess 2 on the disk surface. , and a tangential servo function that corrects linear velocity changes caused by eccentricity of the disk 1 must be realized with high precision. Tracking servo and tangential servo are performed by deflecting a light beam.

There are two ways to deflect the light: one is to move the objective lens in a plane perpendicular to the optical axis, and the other is to rotate a mirror (galvano mirror, hereinafter the same) to utilize the change in angle of the reflected light. The method is known. When moving the objective lens,
Since the control frequency needs to be high, the movable parts need to be lightweight. However, even if the weight of the movable part can be reduced, there is a limit, and this will be disadvantageous when this device is used in a vehicle-mounted device with a lot of vibration in the future. On the other hand, since the method of rotating the mirror requires only a small rotation angle, it is possible to obtain a high servo frequency and is advantageous for use in places with a lot of vibration.

Therefore, a system that rotates a mirror has been put into practical use. A conventional galvano mirror rotation support device will be explained with reference to FIG. 2. Numeral 3 is a rod-shaped magnet, both of which have polarity as shown. magnet 3
Outer yokes 4 and 5 are attached to the outside of both ends, and a center yoke 6 is attached to the center. A projection 7 whose upper end is a knife edge is attached to the center of the upper part of the center yoke 6, and a bobbin 8 is placed on top of the projection 7.
The protrusion 7 and the bobbin 8 are bonded together with a rubber adhesive 9, and the bobbin 8 is tilted on the protrusion 7 but not detached. A coil 10 is wound around the outer periphery of the bobbin 8, and a mirror 11 is attached to the upper surface.

In the conventional galvanometer mirror rotation support device having such a configuration, when DC current is applied to the coil 10,
Depending on the direction of the current, the bobbin 8 rotates and tilts to the left or right in the figure, thereby directing the mirror 11 in a desired direction. Note that the inclination angle of the bobbin 8 can be changed by adjusting the current value. Since this device uses adhesive 9, it has the following problems.

That is, if we consider now that the adhesive 9 is not used, the bobbin 8, coil 10, mirror 11
As the frequency of the driving force increases, the amplitude of the movable part consisting of
There is no phase lag and the servo circuit responds well. However, when using adhesive,
Due to the resistance, the amplitude of the moving part becomes smaller,
Furthermore, since a phase shift occurs, there is a problem that the stability of the servo system deteriorates when there is disturbance vibration. Further, when a mechanism such as mechanically providing a rotating shaft is employed, it becomes difficult to prevent backlash and the like, and there is a problem that the apparatus becomes complicated.

An object of the present invention is to provide a galvanometer mirror rotation support device that solves these problems. For this reason, the present invention has a galvano mirror whose position can be changed by the electromagnetic action of a coil and a magnet. The pair of grooves is further supported by a mirror support plate having another pair of arcuate grooves provided in a direction perpendicular to the pair of grooves on the outer periphery of the pair of grooves, and the mirror support plate is partitioned into the two pairs of arcuate grooves of the mirror support plate. A large-diameter reinforcing ring with a tracking coil attached and a small-diameter reinforcing ring with a tangential coil attached are attached to the area where the tracking coil is attached. The structure is equipped with a magnet.

One embodiment of the present invention will be described with reference to FIG. 3. Reference numeral 12 is a mirror, which is supported by a mirror support plate 13, which will be described next. The mirror support plate 13 is made of an elastic circular thin plate of phosphor bronze or the like, and has a mirror mounting portion 13a in the center. A pair of arcuate grooves 13b, 13b are provided on the outer periphery of the mirror mounting portion 13a, facing each other. And this pair of grooves 13b,
The pair of grooves 13 are further provided on the outer peripheral portion of 13b.
Another pair of grooves 13 in the direction orthogonal to b and 13b.
c, 13c are provided facing each other.

By attaching the mirror 12 to the mirror support plate 13 in this manner, the mirror 12 can be tilted in any direction with respect to the plane of the mirror support plate 13 when an external force is applied to the mirror 12. The mirror support plate 13 is assembled to the case 14 as follows. That is, the case 14 has an annular shape, and the coil housing portions 15a, 1 are provided inside the case 14.
5b will be accommodated. The coil accommodating parts 15a and 15b are positioned in orthogonal directions, and accommodate, respectively, a tracking coil 18 and a tangential coil 19 that are oriented in mutually orthogonal directions, as will be described later. .

The above-mentioned yoke 15 is located at the lower part of the inside of the case 14, and acts like a bottom plate. An annular magnet 16 is attached to the upper part, and a plate-shaped yoke 17 covers the upper part. As shown in the figure, the magnet 16 is polarized and magnetized so that the north and south poles are at the upper and lower ends. In addition to the central hole 17a, the yoke 17 has two holes 17b and two holes 17c perpendicular to each other, into which a tracking coil 18 and a tangential coil 19, which will be described next, are inserted. ing.

The tracking coil 18 has a large diameter reinforcing ring 2
0, and the tangential coil 19 is attached to a small diameter reinforcing ring 21. These reinforcing rings 20, 21 are attached to portions of the mirror support plate 13 defined by the two pairs of arcuate grooves 13b, 13b and 13c, 13c. When a direct current is applied to the tracking coil 18 and the tangential coil 19, the reinforcing rings 20 and 21 are inclined due to attraction and repulsion caused by the magnetic action with the magnet 16. A reinforcing ring 22 having a larger diameter is attached to the outer periphery of the reinforcing ring 20, and the above-mentioned mirror support plate 13 is fixed to the upper part of the reinforcing ring 22 at the outer periphery.

This galvano-mirror rotation support device configured in this manner has the reinforcing rings 20, 21 by passing a direct current of a predetermined magnitude in a predetermined direction through the tracking coil 18 and the tangential coil 19.
can be given a desired angle of inclination. Since the upper surfaces of the reinforcing rings 20 and 21 are attached to the lower surface of the mirror support plate 13 in contact with each other, a desired angle can be given to the mirror 12 via the mirror mounting plate 13.

Since the present invention is constructed as described above, it has the advantage that the mirror can be tilted smoothly, without phase delay, and with less power consumption than other conventional structures. Furthermore, the structure in which the mirror is attached to the mirror support plate has the advantage that it can be made thin as a whole.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a part of an optical disk, FIG. 2 is a sectional view of a conventional galvano mirror rotation support device, and FIG. 3 is an exploded perspective view of an embodiment of the present invention. . DESCRIPTION OF SYMBOLS 1...Disk, 12...Mirror, 13...Mirror support plate, 13a...Mirror mounting part, 13b,
13c... Groove, 16... Magnet, 18... Tracking coil, 19... Tangential coil, 20, 21... Reinforcement ring.

Claims (1)

[Scope of utility model registration request] In an optical deflection device applied to an optical signal recording device that optically records signals on a disk or an optical signal reproducing device for a disk on which signals are optically recorded, the attitude is determined by the electromagnetic action of a coil and a magnet. The galvanometer mirror to be changed is mounted in the center, has a pair of arcuate grooves facing each other on its outer periphery, and further extends in the outer periphery of the pair of grooves in a direction perpendicular to the pair of grooves. a large diameter reinforcing ring supported by a mirror support plate having another pair of arcuate grooves provided therein, and having a tracking coil attached to a portion of the mirror support plate defined by the two pairs of arcuate grooves; The tracking coil is a small-diameter reinforcing ring with a tangential coil attached in the orthogonal direction, and an annular magnet that is vertically polarized and magnetized is attached to the outer periphery of these two reinforcing rings. A galvano mirror rotation support device featuring: