JPH0458660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive device for moving an optical system, and more particularly to a drive device that can move an optical system two-dimensionally. This kind of drive device is
For example, it is effectively applied to an optical head used in an optical information recording/reproducing device to optically record information on a recording medium or optically read recorded information from a recording medium.

[Conventional technology]

BACKGROUND ART In various optical instruments, the entire optical system or a part of the optical system is moved as necessary, and by such movement, a desired imaging relationship that changes the optical path can be obtained.

The movement of the optical system is achieved by focusing, which is realized as movement along the optical axis when the object moves in the direction of the optical axis, and tracking, which is realized when the object moves in the direction perpendicular to the optical axis. In some cases, this is realized as movement in a direction perpendicular to the optical axis.

A specific example of such optical system movement is the optical head of an optical information recording/reproducing device. In an optical information recording/reproducing device, a laser beam emitted from a light source is focused by an optical system and irradiated onto a recording medium such as a disk. Information is recorded. In the case of a disk-shaped recording medium, this information recording is carried out by forming concentric or spiral minute pattern rows (information tracks) while rotating the recording medium.
As the micropattern, unevenness, presence or absence of holes, change in light reflectance, direction of magnetization, etc. are used depending on the type of recording medium used.

When reproducing information recorded on a recording medium, a light beam of a certain intensity is irradiated onto the recording pattern of the recording medium, and the light beam modulated by the recording pattern is guided to a light receiving element by an optical system and the recorded information is read by photoelectric conversion. Regeneration takes place.

An optical head is used as a device that includes an objective optical system for recording or reproducing optical information as described above.

By the way, in optical information recording and reproduction, since the recording pattern is minute, it is necessary to irradiate the recording medium with a beam of light from the optical head in such a way as to obtain a sufficient focus state, and at the same time, during reproduction, it is necessary to It is necessary for the spot to follow the information track well. Therefore, in the optical head, the focusing state and tracking state to the recording medium are constantly detected, and if these are about to deviate from the appropriate range, the optical system of the optical head or a part of it is moved to correct the focusing state. Control is also performed to maintain the tracking state.

For such focusing control and tracking control, conventional optical heads are provided with focusing control drive means and tracking control drive means, respectively. Each drive means has a coil fixed to the objective lens and a magnet for generating a magnetic field at the position of the coil, and focusing control and tracking control are performed by controlling the amount of current applied to the coil. ing.

[Problem that the invention seeks to solve]

Therefore, in the conventional optical head as described above, access to the information track is performed by moving the entire head, including the relatively heavy driving means including the coil and magnet, using another driving means. There is. Therefore, there is a problem in that the weight of the movable part during access is large, making high-speed access difficult. Furthermore, since the conventional optical head as described above requires a large number of drive means, the number of parts increases, resulting in an increase in size and cost.

As mentioned above, the problem that it is difficult to move an optical system two-dimensionally at high speed over a relatively long distance range and that it is difficult to make contact is not limited to driving the optical system in the optical head, but also applies to optical systems. System 2
Present throughout the device for driving dimensional movement.

[Means for solving problems]

According to the present invention, the above problems are solved,
The optical system can be moved two-dimensionally over a desired distance at high speed with a relatively simple configuration, and at least one pair of movers can be moved independently by a driving source along the direction connecting them. Each movable element is connected to one end of a connecting member extending in a direction diagonal to the direction in which they are connected, and the optical system is supported by the other end of each connecting member. An optical system driving device is provided, characterized in that each of the movable elements holds a plane reflecting mirror for cooperating with and guiding light beams parallel to the direction connecting them to the optical system.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic side view showing an embodiment of an optical system driving device according to the present invention. This embodiment is applied to driving an objective lens of an optical head.

In FIG. 1, 2 and 4 are a pair of movers, and 6 and 8 are wheels attached to the movers 2 and 4, respectively. The movers 2 and 4 are movable independently in the direction connecting them (ie, the X ₁ -X ₂ direction), and 10 is a rail that is a guide member for guiding the movement. That is, the wheels 6 and 8 are mounted on the rail 10, and therefore each movable element 2,
4 is independently X ₁ −X ₂ if an external force is given
can move along the direction.

Each movable element 2, 4 has a connecting member 12, 1, respectively.
3, 14, and 15 are connected at one end. This connection is made by a hinge that is rotatable about a direction perpendicular to the plane of the drawing. These connecting members 12, 13, 14, 15 are arranged obliquely to the _X1 - _X2 direction, and the connecting ends of these connecting members 12, 13, 14, 15 on the opposite side An optical system support member 16 is connected to the end. This connection is also made by a hinge that is rotatable about a direction perpendicular to the plane of the drawing. Further, the connecting members 12, 13, 14, 15 have the same length, and the movable element 2 and the connecting member 1
2, 13 and the support member 16 constitute a parallelogram link, and similarly the mover 4, the connecting members 14, 15
and the support member 16 constitute a parallelogram link. An objective lens 18, which is an optical system, is fixedly supported by the support member 16. Y is objective lens 18
, and is perpendicular to the X ₁ −X ₂ direction.

Each movable element 2, 4 can be independently moved in the _X1 - _X2 direction by a drive source (not shown).

Reference numeral 20 denotes an optical disk which is an optical information recording medium, and is driven and rotated by a drive motor 22 in a plane perpendicular to the Y direction, and at a position P intersecting the optical axis Y, the information track is in the X ₁ -X ₂ direction. It rotates so that it runs vertically.

24 is a semiconductor laser which is a light source, and the diverging light emitted from the light source 24 is made into a parallel beam by a collimator lens 26. The parallel light flux is converted into a parallel light flux traveling in the X ₁ -X ₂ direction by the beam splitter 28 .

On the other hand, plane reflecting mirrors 30 and 32, which are light deflecting means, are attached to the movers 2 and 4, respectively. Then, the parallel light beam from the beam splitter 28 is reflected by the reflecting mirror 32.
and is reflected by the reflecting mirror 30 to form a parallel beam of light along the optical axis Y to the objective lens 18.
, and is focused by the objective lens 18 to form a minute spot at position P on the disk 20. As shown in FIG. 1, in the device of this embodiment, the angle formed by the direction of the light flux incident on the reflecting mirror 32 from the light source side and the direction of the reflected light flux is
The angle between the direction in which the reflected light flux enters the reflecting mirror 30 and the direction of the reflected light flux is 60 degrees.

The light beam reflected at the position P of the disk 26 is made into a parallel light beam traveling in the Y direction by the objective lens 18, and after being reflected by the reflecting mirrors 30 and 32, it passes through the beam splitter 28 and is focused by the condenser lens 34. The photodetector 36 is exposed to light.
For example, the light is made incident on a two-split photodetector divided into two in the Y direction. In this way, it is possible to obtain the recorded information recorded on the recording medium 20 by the photodetector 36, and also to obtain a tracking error signal by the push-pull method.

In this embodiment, the objective lens 18 is moved in _the tracking direction (i.e. _, X ₁ −X ₂ direction) and not in the focusing direction.

Furthermore, in the device of this embodiment, the objective lens 18 is moved only in the focusing direction by moving the movable elements 2 and 4 by the same distance in opposite directions along the _X1 - _X2 direction by the movable element drive source. It does not move in the tracking direction. FIG. 2 is a schematic partial side view showing the state of the movable elements 2, 4 and the vicinity of the optical system 18 at this time.

Thus, according to the apparatus of this embodiment, by appropriately setting the moving distance of each movable element 2, 4 along the _X1 - _X2 direction, the objective lens 18 can be moved in the direction of its optical axis and in the direction perpendicular thereto. It can be moved two-dimensionally, and thereby tracking control and focusing control of the optical information recording/reproducing apparatus can be performed simultaneously. Further, according to the apparatus of this embodiment, the objective lens 18 can be moved along the X ₁ -X ₂ direction and the Y direction over a considerable stroke, and random access to the information track is possible.

In addition, in this example device, from the light source side
_A reflecting mirror ₃₀ ,
32 to the objective lens 18, even if the movable elements 2 and 4 move, the parallel light beam from the light source side is always incident on the objective lens 18, making it possible to perform comparisons such as random access to information tracks. There is no need to move the light source even when moving the target over long distances.

Furthermore, in the apparatus of this embodiment, the objective lens 1
The optical axis Y of 8 is always located at the center of the two movable elements 2 and 4 regardless of the distance between them, and the optical axis Y of the two reflectors 3
Since 0,32 has a specific arrangement as above,
Even when the distance between the movers 2 and 4 changes, the parallel light flux entering the reflecting mirror 32 from the light source side is 2.
After being reflected by the two reflecting mirrors 32 and 30, the light always enters the objective lens 18 along the same optical path. Therefore, the reflected light beam from the recording medium 20 also always enters the reflecting mirror 30 along the same optical path, and after being reflected by the two reflecting mirrors 30 and 32, always goes to the beam splitter 28 along the same optical path. become. That is, the optical path from the light source 24 to the objective lens 18 changes only between the two reflecting mirrors 30 and 32, as shown by A and B in FIG. 2, but can remain unchanged in other parts. Thus, no error occurs in the tracking error detection signal from the photodetector 36, and furthermore, it is possible to use a lens 18 with the minimum required diameter.

In the above embodiments, a drive source for moving the movers 2 and 4 is not particularly explained, but as a drive source for the mover in the device of the present invention, electromagnetic means, electrostatic means, piezoelectric means, etc. It is possible to use an appropriate driving force generating means such as mechanical means or a combination thereof.

Further, in the above embodiment, the movers 2 and 4 are connected to the rail 10, which is a guide member, via the wheels 6 and 8.
However, in the apparatus of the present invention, the movable element may be movable by sliding with respect to the guide member.

Further, in the above embodiments, a parallelogram link is used as the connecting member, but the connecting member in the device of the present invention connects the movable element and the optical system with appropriate bending elasticity. You may also use one that does.

In the above embodiments, the optical system to be driven is an objective lens, but it goes without saying that the optical system driven by the driving device of the present invention is not limited to an objective lens, and all optical systems are It may be any optical system component that constitutes at least a part of the system, and may be a concave lens other than a convex lens, a reflecting mirror, a prism, or the like.

Further, although the above embodiments are applied to driving the objective lens of an optical head, the driving device of the present invention can be applied to driving the optical system of all other optical devices.

Further, in the above embodiment, a case is shown in which there is one pair of movers, but in the apparatus of the present invention, two or more pairs of movers may be arranged. In this case, each pair of movers moves in parallel, one of the movers of each pair is connected and the other is connected, and the two connected mover groups are connected. Connect parts.

〔Effect of the invention〕

According to the apparatus of the present invention as described above, the following effects can be obtained.

(1) There are few moving parts and the optical system can be moved two-dimensionally over a considerable distance.

(2) Since the weight of the movable parts is relatively small, the moving speed can be increased, and especially when a pair of movable elements move in the same direction, a large acceleration can be obtained.

(3) Since each movable element holds a plane reflecting mirror, even if the movable element moves, the light flux from the fixed light source side can always be guided to the optical system.

[Brief explanation of the drawing]

FIG. 1 is a side view of the device of the present invention, and FIG. 2 is a partial side view of the device in its operating state. 2, 4...Mover, 6, 8...Wheel, 10...
Guide member, 12, 13, 14, 15... Connection member, 18... Lens, 30, 32... Reflector.

Claims (1)

[Claims] 1. At least one pair of movable elements are arranged so as to be movable independently by a driving source along a direction in which they are connected, and each movable element has a movable element that is oblique to the direction in which they are connected. One end of the connecting member extending in the direction is connected, and an optical system is supported by the other end of each connecting member. An optical system driving device, characterized in that a flat reflecting mirror for guiding the optical system to the optical system is held. 2. The optical system driving device according to claim 1, wherein the optical system has an optical axis in a direction perpendicular to the direction connecting the pair of movers within a plane determined by the direction of the pair of connecting members. 3. The optical system drive device according to claim 1, which is provided with a guide member for guiding the movement of the movable element. 4 A light beam in a direction connecting the pair of movable elements is reflected by a first reflecting mirror, and the reflected light beam is reflected by a second reflecting mirror and guided to the optical system, and the above-mentioned first Claim 1, wherein the sum of the first angle between the incident light flux and the reflected light flux regarding the reflecting mirror and the second angle formed between the incident light flux and the reflected light flux regarding the second reflecting mirror is 90 degrees. Optical system drive device in item 1. 5. The optical system driving device according to claim 4, wherein the first angle is 30 degrees and the second angle is 60 degrees.