JPS62226431A - Optical system driving system - Google Patents

Abstract

PURPOSE:To prevent resonance at the time of driving an optical system by placing the optical system on the side of a base stand instead of on the side of the 1st supporting means and holding said system by an optical system holding means. CONSTITUTION:An objective lens holding body 44 has a main part close to a base stand vertical part 30b from a place where a bearings 42a and 42b are provided, and an objective lens 46 is placed on the main body. Namely, the objective lens 46 is not positioned on spindles 40a and 40b and the bearings 42a and 42a but on the base stand vertical part 30b side. A coil 48 is fitted on the side opposite to the side facing the base vertical part 30b of an objective lens holding stand 44, and a permanent magnet 32 and a column 34 are arranged at the position corresponding to said side. Thus the objective lens 46 is not positioned on the spindles 40a and 40b but on the side of the base stand vertical part 30b side, and therefore the permanent magnet 36 is fitted on the side of the base stand vertical part 30b side. Accordingly even if the permanent magnet 32 and the column 34 are fitted on the side opposite to the base stand vertical part 30b side of the spindles 40a and 40b, the length l2 of a base stand horizontal part 30a is comparatively short.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical system driving device, and particularly to a device capable of driving an optical system two-dimensionally. Such an optical system drive device is suitably used, for example, to drive an objective lens of an optical head in an optical information recording/reproducing device.

[Conventional technology and its problems]

Conventionally, optical information recording and reproducing devices have been put into practical use, which record information on a recording medium and/or reproduce information recorded on the recording medium while irradiating the surface of the information recording medium with a laser beam in a spot shape. has been made into

An example of such a device is an optical disk device. On an optical disk, which is a recording medium on which information is reproduced by an optical disk device, an information track consisting of a row of information pits with a width of about 1 to 2 μm and a length of about 1 to 3 μm is formed in a spiral or concentric circle shape. . When reproducing the information recorded as the information bit string, without rotating the optical disk, a laser beam is irradiated from an optical head in the form of a minute spot onto the information track of the optical disk, and the information focus string is scanned by the beam spot. . When a photodetector detects the reflected or transmitted light of the light irradiated onto the optical disk surface in this way, the optical difference of the light incident on the photodetector depends on whether or not there is an information focus at the beam spot position. Character changes. In this way, a reproduced signal corresponding to the information bit string can be obtained.

One of the features of optical discs is that they are capable of high-density recording, so the information bits are quite small as mentioned above.
For this reason, in optical disk devices, in order to accurately reproduce information, it is necessary for the light beam spot to always accurately follow the information track (tracking) and for the light beam spot to always be focused on the information track (focusing). be.

For this reason, -i, the optical disk device performs auto-tracking control to correct optical beam spot position deviations caused by eccentricity of the optical disk, and auto-focusing control to correct focusing deviations caused by optical disk warping, etc. .

As a method for realizing such auto-tracking control and auto-focusing control, the objective lens, which is the light beam focusing means of the optical head, is movable in the direction of the optical axis of the lens and in the direction orthogonal thereto using a wing-like structure. A method is generally used in which the objective lens is driven so as to eliminate the positional deviation and defocusing of the light beam spot based on detection signals of the positional deviation and defocusing of the light beam spot.

FIG. 2 is a perspective view showing a conventional objective lens driving device for an optical head having means for such auto-tracking control and auto-focusing control.

In FIG. 2, 2 is a base, and a yoke 6 to which a permanent magnet 4 is attached is fixed on the base. One end of a pair of temporary springs 8a and 8b, each located in a vertical plane, is fixed to the yoke, and the opposing vertical end surface of a square relay plate 10 is fixed to the other end of the leaf spring. One end of a pair of leaf springs 12a and 12b, each located in a horizontal plane, is fixed to the opposing horizontal end surfaces of the relay plate 10, and an objective lens holder 14 is fixed to the other end of the leaf spring. ing. 16 is an objective lens held by the holder. On the other hand, a yoke 20 to which a permanent magnet 18 is attached is fixed to the base 2.

A coil 22 wound horizontally is attached to the objective lens holder 14 on the side of the permanent magnet 4, and the coil 22 is arranged so as to surround a part of the yoke 6.

A letter coil 24 wound in the vertical direction is attached to the permanent magnet 18 side of the objective lens holder 14.
The coil is arranged to surround a part of the yoke 20.

Note that the base 2 is provided with a through hole 26 below the objective lens 16, thereby ensuring an optical path for the light beam passing through the objective lens 16.

In the objective lens drive device as described above, the relay plate 10
, a portion consisting of the temporary springs 12a, 12b, the objective lens holder 14, the objective lens 16, and the coil 22°24 is horizontally swingable with respect to the yoke 6 via the plate springs 8a, 8b. This realizes horizontal movement of the objective lens 16 (ie, movement for auto-tracking control). This movement is driven by the interaction with the magnetic field of the permanent magnet 4 by passing a current through the coil 22.

Further, a portion consisting of the objective lens holder 14, the objective lens 16, and the coils 22 and 24 is a plate spring 12a.

The objective lens 16 can be oscillated in the vertical direction with respect to the relay plate 10 via the relay plate 12b, thereby realizing vertical movement of the objective lens 16 (that is, movement for autofocusing control). This movement is driven by the interaction with the magnetic field of the permanent magnet 18 by passing a current through the coil 24.

However, in the conventional objective lens driving device as described above, since the movable part is supported in two stages by temporary springs, the optical axis of the objective lens may be tilted due to twisting of the leaf spring, etc. There has been a problem in that resonance occurs with high-frequency drive signals, resulting in unstable operation.

[Background of the invention]

As a solution to the problems of the conventional objective lens drive device as described above, an objective lens drive device as shown in FIG. 3 can be considered.

In FIG. 3, 30 is a base, and the base is a horizontal part 3.
It has an angular shape having a vertical portion 30b and a vertical portion 30b. A column 34 to which a permanent magnet 32 is attached is fixed on the horizontal base portion 30a, and a ring-shaped permanent magnet 36 is fixed to the base horizontal portion 30a.
is fixed. On the other hand, the base vertical part 30b has four equivalent wires 38a, 38b, 38c having bending elasticity.
, 38d are fixedly supported, and the wire 38a
.

Both ends of a shaft 40a are fixed to the other end of the wire 38c, and both ends of a shaft 40b are fixed to both ends of the wires 38b and 38d. Wires 38a, 38b.

38c and 38d both extend horizontally, wires 38a and 38C are arranged at the same height, wires 38b and 38d are arranged at the same height,
Further, the wire 38b is located below the wire 38a, and the wire 38d is located below the wire 38c. Therefore, axis 4
0a and 40b are arranged horizontally and parallelly, and the axis 4
0b is located below the axis 40a. A bearing 42a is slidably and rotatably coupled to the shaft 40a, and a bearing 42a is coupled to the shaft 40b.
A bearing 42b is slidably and rotatably coupled to the bearing 42b.

44 is an objective lens holder, and the bearings 42a, 42
b is fixed to the holder 44.

46 is an objective lens held by the objective lens holder 44.

A flattened coil 48 wound horizontally is attached to the surface of the objective lens holder 44 facing the permanent magnet 32, and one of the two vertically wound portions of the coil is attached. The winding portion is arranged to face the permanent magnet 32. A coil 50 is attached to the lower part of the objective lens holder 44 and is arranged coaxially inside the annular permanent magnet 36.

Note that a through hole (not shown) is provided in the base horizontal portion 30a below the objective lens 46, thereby ensuring an optical path for the light beam passing through the objective lens 46.

FIG. 4 is a perspective view showing details of the shafts 40a and 40b. A Teflon-based resin coating layer 41 is formed on the surface of the central portion of the shaft, thereby reducing sliding friction with the bearings 42a, 42b.

In the objective lens driving device as described above, the coil 48
By passing a current through the shaft 40a, a portion consisting of the objective lens holder 44, the objective lens 46, and the coils 48 and 50 is moved to the shaft 40a via the bearings 42a and 42b due to the interaction with the magnetic field by the permanent magnet 32.

40b and moves in the horizontal direction, thereby performing auto-tracking. Since this auto-tracking drive is not performed via a spring member, resonance does not occur even with high frequency drive.

In addition, by passing current through the coil 50, the permanent magnet 36
By interaction with the magnetic field due to the axis 40a.

40b, bearings 42a, 42b, objective lens holder 44,
The portions consisting of the objective lens 46 and the coils 48, 50 are the wires 38a, 38b, 38c.

By bending the lens 38d, it swings vertically, thereby performing autofocusing. The wire 38a is used during this autofocusing drive.

38b, 38c, and 38d are similarly deformed so that shaft 40
Since the parallel relationship and vertical positional relationship between a and 40b remain unchanged, autofocusing is performed without causing the optical axis of the objective lens 46 to tilt.

According to such an objective lens driving device, the above-mentioned problems of the conventional device as shown in FIG. 2 can be solved.

However, in the objective lens driving device as shown in FIG. 3, in order to obtain desired characteristics, the wire 38a,
38b, 38c, and 38d have a certain length, and the objective lens 46 has a shaft 40a.

40b is held by the objective lens holder 44 at a position farther from the base vertical part 30b, and the permanent magnet 36 is arranged at the corresponding position, so the length 1 of the base horizontal part 30a is However, there are limits to the miniaturization of the device.

Therefore, the present invention solves both the problems of the conventional drive device as shown in FIG. 2 and the problems of the drive device as shown in FIG. 3, and provides good operation. Another object of the present invention is to provide an optical system driving device that can be downsized.

[Invention (already required)]

According to the present invention, the above object is to provide an optical system, a means for holding the optical system, a first support means for supporting the optical system holding means so as to be movable in a first direction, and a first support means for supporting the optical system holding means so as to be movable in a first direction. a second support means connected to the first support means and movably supports the optical system holding means in a second direction different from the first direction; a base connected to the second support means; [Embodiment] Achieved by an optical system driving device, characterized in that the optical system is held by the optical system holding means at a position closer to the base than the first supporting means. Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the optical system driving device of the present invention. This embodiment is applied to driving an objective lens of an optical information recording/reproducing device.

In FIG. 1, members having the same functions as in FIG. 3 are given the same reference numerals.

In FIG. 1, 30 is a base, and the base is a horizontal part 3.
It has an angular shape having a vertical portion 30b and a vertical portion 30b. A column 34 to which a permanent magnet 32 is attached is fixed on the horizontal base portion 30a, and a ring-shaped permanent magnet 36 is fixed to the base horizontal portion 30a.
is fixed. On the other hand, the base vertical part 30b has four equivalent wires 38a, 38b, 38c having bending elasticity.
, 38d are fixedly supported, and the wire 38a
.

Both ends of a shaft 40a are fixed to the other end of the wire 38C, and both ends of a shaft 40b are fixed to both ends of the wires 38b and 38d. Wires 33a, 38b.

38c and 38d both extend horizontally, wires 38a and 38C are arranged at the same height, wires 38b and 38d are arranged at the same height,
Further, the wire 38b is located below the wire 38a, and the wire 38d is located below the wire 38c. Therefore, axis 4
0a and 40b are arranged horizontally and parallelly, and the axis 4
0b is located below the axis 40a. A bearing 42a is slidably and rotatably coupled to the shaft 40a, and a bearing 42a is coupled to the shaft 40b.
A bearing 42b is slidably and rotatably coupled to the bearing 42b.

44 is an objective lens holder, and the bearings 42a, 42
b is fixed to the holder 44.

46 is an objective lens held by the objective lens holder 44.

A flattened coil 48 wound horizontally is attached to the surface of the objective lens holder 44 facing the permanent magnet 32, and one of the two vertically wound portions of the coil is attached. The winding portion is arranged to face the permanent magnet 32. A coil 50 is attached to the lower part of the objective lens holder 44 and is arranged coaxially inside the annular permanent magnet 36.

Note that a through hole (not shown) is provided in the base horizontal portion 30a below the objective lens 46, thereby ensuring an optical path for the light beam passing through the objective lens 46.

As shown, the apparatus of this embodiment differs from the apparatus shown in FIG. 3 above in the arrangement of the objective lens 46.

That is, the objective lens holder 44 has a main body extending from the portion where the bearings 42a and 42b are attached to the base vertical portion 30b, and the objective lens 46 is located here. That is, the objective lens has shafts 40a, 40b and bearings 42a, 42b.
It is located closer to the base vertical portion 30b than the base vertical portion 30b. The coil 48 is connected to the base vertical portion 30 of the objective lens holder 44.
It is attached to the surface opposite to the side facing b, and a permanent magnet 32 and a column 34 are arranged at corresponding positions. Further, the coil 50 is attached to the objective lens holder 44 below the objective lens 46, and the permanent magnet 36 is arranged at a position corresponding to this.

In the apparatus of this embodiment as described above, the objective lens is driven by the same operation as the apparatus shown in FIG. 3 above.

In the apparatus of this embodiment, the objective lens 46 is connected to the axis 40a,
Since the permanent magnet 36 is located closer to the base vertical part 30b than the '40b, the mounting position of the permanent magnet 36 can be on the base vertical part 30b side, and therefore the mounting position of the permanent magnet 32 and the column 34 is the shaft 40a.
, 40b on the side opposite to the base vertical part 30b,
The length 12 of the base horizontal portion 30a may be relatively short. That is, compared to the length 1) in the apparatus shown in FIG. 3 above,
<β8.

In the above embodiment, the bearing 42a is fixed to the objective lens holder 44 as the first support means.

42b and wires 38a, 38b serving as second support means.

38c and 38d, the first supporting means in the present invention is not limited to this, and conversely, the first supporting means is fixed to the optical system holding means. It may consist of a set of a fixed shaft and a bearing fixed to the second support means, and other suitable means are also possible.

Further, in the above embodiment, four wires 38 having appropriate bending elasticity are arranged in parallel as the second support means.
a, 38 b, 38 c, and 38 d are used, but the second supporting means in the present invention is not limited to this, and any appropriate means such as a pair of plate springs can be used. .

Further, although the above embodiment is applied to driving an objective lens of an optical information recording/reproducing apparatus, the present invention can be applied to driving other appropriate optical systems. The optical system to be driven is not limited to a lens or a lens system, but may be a mirror, a prism, or a composite optical system including these.

〔Effect of the invention〕

According to the present invention as described above, there is almost no resonance when driving the optical system, the operation is performed well, and it is possible to downsize the device.

[Brief explanation of drawings]

1, 2, and 3 are perspective views of the optical system driving device. FIG. 4 is a perspective view of the shaft. 30: Base, 30a: Horizontal base portion, 30b = Vertical base portion, 32.36: Permanent magnet, 38a, 38b. 38C, 38d: wire, 40a, 4Qb: shaft, 42a
, 42b: bearing, 44: objective lens holder, 46: objective lens, 4s, so: coil. Figure 2 Figure 4

Claims (3)

[Claims] (1) an optical system, means for holding the optical system, first support means for supporting the optical system holding means movably in a first direction, and an optical system connected to the first support means; a second support means for movably supporting the system holding means in a second direction different from the first direction; and a base connected to the second support means, the optical system An optical system driving device, characterized in that the optical system holding means holds the optical system at a position closer to the base than the first supporting means. (2) The optical system drive device according to claim 1, wherein the first support means is a combination of a shaft and a bearing. (3) The optical system drive device according to claim 1, wherein the second support means is comprised of a pair of rod-shaped bodies having bending elasticity arranged parallel to each other.