JPS5929991B2 - position control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position control device, and more particularly to a position control device for controlling the relative position between a recording medium and a recording/reading section in an optical information reproducing device.

Generally, magnetic tape is the most widely used recording medium for recording video, audio, etc., but this is because magnetic tape is relatively easy to record and play back, and it has a large recording capacity. It is.

However, recently, records using an optical reproduction system have begun to attract attention as a recording medium that has a recording capacity comparable to that of magnetic tapes and is also cheaper. Normally, a record is played back by bringing a needle into contact with the record, but this optical playback method does not directly touch the record, but rather irradiates the record with laser light to read information. Therefore, recorded information can be maintained semi-permanently, and high-density, high-quality information can be recorded and reproduced. Furthermore, vinyl records have many advantages, such as being the same size as ordinary audio records and being manufactured using the same pressing method, which is why they are seen as promising as a new storage medium that surpasses magnetic tape. FIG. 1 is an explanatory diagram showing an example of an optical information reproducing apparatus for reproducing this type of record. In the figure, reference numeral 1 denotes a disk-shaped record that is driven by a motor 2 and rotates at a predetermined rotational speed.As shown in FIG. Transparent disc part Ib engraved in the shape of
, a reflective metal film lc attached to the engraved surface side of the uneven bit 1a, and a protective film ld that protects the reflective metal film Ic. Reference numeral 3 denotes a laser device that sends a laser beam 4 to a recording/reading section T via a first splitter 5 consisting of a pair of triangular prisms and a total reflection mirror 6.

The recording/reading section 7 has one lens 7a, and scans the record 1 in the radial direction while focusing the laser beam 4 on a predetermined position on the record 1. Here, the laser L light 4 is modulated and reflected by the uneven bits 1a of the record 1, and the reflected light 8 passes through the total reflection mirror 6 and the first splitter 5 again, and passes through the second splitter made of three triangular prisms. The reflected light 8 is guided to a splitter 19, and is split into three components 8a, 8b, and 8c by a second splitter 19. Furthermore, each component of the reflected light 8 is converted into an electrical signal by an optical converter 10. Reference numeral 11 denotes a position where a difference signal between electric signals corresponding to components 8a and 8b at both end portions of the reflected light 8 is extracted, and the focal position is corrected for radial deviation, that is, tracking deviation, in the recording/reading section 7. a first amplifier 11 for sending an output signal to the control device; the first amplifier 11 also has a motional feedback circuit 12 from the position control device;
3 compares the electric signal corresponding to the central component 8c of the reflected light 8 with a predetermined reference value, and outputs an output corresponding to the deviation to adjust the focus for the vertical deviation of the recording/reading section 7. This is a second amplifier for transmitting signals to a position control device, and similarly to the first amplifier 11 described above, it has a motional feedback circuit 14 for smooth position control.

15 is an output terminal from which a component 8c containing information included in the reflected light 8 is derived.

However, a relatively problematic aspect of such an optical reproducing device is that the laser beam must be scanned while always focusing the laser beam on a predetermined position on the record.

In other words, since it is completely non-contact, focusing and tracking are complicated, and a highly accurate position control mechanism is required.In particular, it is necessary to detect and correct deviations in the focal position due to vibration or deflection of the record. becomes an essential condition. Therefore, this invention has been made in view of the above points, and an object of the invention is to accurately and smoothly correct the deviation of the focal position caused by the vibration or deflection of a record. The object of the present invention is to provide a position control device for carrying out the invention. In order to achieve such an object, the position control device according to the present invention is provided with an elastic frame movable in only one direction between a pair of opposing electromagnets arranged on the movable direction line. . The present invention will now be described in detail with reference to the drawings.

FIGS. 3A and 3B are plan views and cross-sectional views of main parts of an embodiment of the position control device according to the present invention. It is an elastic frame body, and is fixed on the base 18 by a support column 17 fixed to the inside of the center of the short side surface.19 is the center inside side of the long side surface of the elastic frame body 16, and This is a lens holder whose walls are fixed to two side plates 20 bridged between its longitudinal sides, with the walls of each plate in close contact with each other. mated.

These constitute a position controlled section. 23 is a damper made of silicone rubber, silicone grease, etc., interposed in the gap between the support column 17 and the side plate 20.

Reference numeral 24 designates a pair of electromagnets that are disposed facing each other on the outside of the longitudinal side of the elastic frame 16.

Next, the operation of the position control device configured as described above will be explained using FIG. 4. In the figure, the same parts as in FIG. 3 are denoted by the same reference numerals. Although not shown, when one of the pair of electromagnets disposed opposite to each other on both sides of the elastic frame 16 is driven, the elastic frame 16 is made of a magnetic material. The central part of the longitudinal side is attracted towards the driven electromagnet. When sucked, the surface of the elastic frame 16 that comes into close contact with the support column 17 and the lens holder 19
The lens 22 is bent as shown by the dotted line except for the contact surface, and the position of the lens 22 moves as the lens holder 19 is deflected. In this case, the four corners of the elastic frame 16 are inclined inward, making it easy to bend and deform the frame. Incidentally, the inclination angle θ of the four corners increases or decreases according to the deflection of the lens holder 19, and vibrations generated in the elastic frame 16 during suction deflection are absorbed by the damper 23. Therefore, for example, when correcting the position of the focal point for the radial deviation of the record, that is, the tracking deviation, as shown in FIG. , the lens holder 19 moves linearly in the direction of the arrow in response to the output signal, and the focal position of the lens is corrected quickly and smoothly with high accuracy without shifting the focusing. As described above, according to the positioning leg device according to this embodiment, the lens holder is attached to the elastic frame that is deflected in only one direction, and this is arranged between a pair of opposing electromagnets. Furthermore, by selectively driving the electromagnet, the focal position of the lens relative to tracking displacement can be easily and accurately changed.

FIG. 5 is a plan view of essential parts showing another embodiment of the position control device according to the present invention, and the same parts as in FIG. 3 are denoted by the same reference numerals. In the figure, 25 is an elastic frame made of a magnetic elastic body fixed to a base (not shown) by a support column 26, and 27 is a third elastic frame mounted in the center of this elastic frame 25.
This is a first position control device that integrates the position control device shown in the figure, and the electromagnet 24 of this first position control device 27 is arranged along the longitudinal direction of the elastic frame 25, thereby positioning the device in the y direction. Adjustments are made. Reference numeral 28 denotes a side plate 29 and the support column 26 for supporting the first position control device 27.
A damper is interposed in the gap between the elastic frames 25 and 29, which is a pair of electromagnets disposed facing each other outside the center of the longitudinal side surface of the elastic frame 25.

Here, the base to which the elastic frame 25 is fixed and the base to which the elastic frame 16 of the first position control device is fixed are separated from each other. In the position braking device configured in this way, the same operation as the first position control device 27 is performed,
The lens 22 can be moved in both the X and Y directions.

Further, in the above two embodiments, the structure in which the mutual positional relationship between the lens 22 and the lens holder 19 is unchanged has been described, but the position of the lens 22 is
It may also be possible to move against. Examples thereof will be described below.

In FIG. 6, a magnetic path a is formed by an envelope 30 corresponding to the lens holder 19 of the above embodiment and a permanent magnet 31, and a cylinder is movably held in the envelope 30 via a damper 32. A lens holder 33 having the shape of a ring is partially inserted into a ring-shaped gap 34 provided in the middle of the magnetic path a.

Furthermore, a drive coil 35 and a motional feed coil 36 are wound around the outer peripheral surface of the lens holder 33 within the gap 34. The lens 37 is fitted to the lens holder 33 configured in this manner. Here, if a predetermined drive control signal, for example, an output signal sent from the second amplifier shown in FIG. 1, is applied to the drive coil 35,
Due to the interaction with the magnetic field, the lens holder 33 moves in the direction of the arrow (
The position of the lens 37 is moved by receiving force in the Z direction).
At this time, by feeding back the electric signal induced in the motional feedback coil 36 to the control system of the drive coil, the focal position of the lens can be adjusted accurately, quickly and smoothly. This adjustment corrects the vertical positional deviation in the optical recording/reproducing device described above. Note that the optical path includes the envelope 30 and the permanent magnet 31.
The laser beam passes through the cylindrical lens holder 33 through a through hole 38 that connects and passes through the lens 37 to reach a lens 37, and the lens 37 focuses the laser beam at a predetermined position. FIG. 7 shows another embodiment that achieves the same purpose, and the same parts as in FIG. 6 are denoted by the same reference numerals. The lens holder 33 shown in FIG.
The motional feedback coil 36 is used as a means for detecting the movement of the lens, while the inner edge is fixed to the lens holder 33 and the outer edge is fixed to the envelope 30 via an insulator 39. A bimorph element 40 is used as a detection section. A bimorph device is an electromechanical transducer that generates an electrical signal in response to an applied bending force. In addition, in FIGS. 6 and 7, a magnetically sensitive element such as a Hall element or a magnetoresistive element may be used instead of the motional feedback coil, and a piezoelectric element such as a piezoelectric semiconductor or crystal may be used instead of the bimorph element. is also possible.

As explained above, by combining the configuration in which the lens is movable with respect to the lens holder with the configuration shown in FIG. 3 or FIG. 5, degrees of freedom of movement in two or three directions can be obtained. .

In addition, in the embodiments described above, the case where the elastic frame body is integrally formed has been described, but the present invention is not limited thereto, and the support column and the lens holder (envelope) are integrally formed. ) etc., which are fixed to the position-controlled part, do not need to have elasticity, and the parts other than the side surface facing the electromagnet do not need to be made of magnetic material.

For this reason, the elastic frame may be constructed using several types of materials that are suitable for each purpose, and in particular, the magnetic body portion may be configured such that pieces of magnetic material are separately attached to the side surfaces. Further, in the drawings, the elastic frame has a box shape with four right-angled corners, but the shape is not particularly limited as long as the shape has enough room to allow for deflection deformation in the portions corresponding to the four corners. Furthermore, the support column can be attached to any position inside or outside the elastic frame. Furthermore, it goes without saying that the position control device according to the present invention can be applied to optical equipment other than optical recording/reproducing devices.

In this case, the moving directions of the optical elements such as lenses are not limited to the X, y, and z directions that intersect at right angles to each other, but it is of course possible to set the moving directions at various angles. As explained above, the position control device according to the present invention includes an elastic frame that is flexible and deformable in only one direction and that is arranged between at least one pair of electromagnets, and a positioning chest is attached to the elastic frame. , the elastic frame is deflected and deformed by using the attractive force of the electromagnet against the elastic frame to perform a predetermined linear movement in the direction opposite to the electromagnet of the position controlled part, so the drive signal applied to the electromagnet is By appropriately selecting the position control unit, the linear movement of the position control unit can be performed accurately, quickly and smoothly with a simple structure. When correcting misalignment, etc., the tracking is moved linearly in the alignment direction, and no changes occur in other directions.C, the distance between the optical system lens and the record is kept constant, and the vertical movement is caused by slight movement. This eliminates focusing errors and enables highly accurate control. Furthermore, by combining a plurality of position control devices of this type, various excellent effects can be achieved, such as making it possible to control movement in any direction.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of an optical recording/reproducing device;
3A and 3B are a plan view and a cross-sectional view of the main part showing an embodiment of the position control device according to the present invention, and FIG. 4 similarly explains the operation. FIG. 5 is a plan view of a main part similarly showing another embodiment, and FIGS. 6 and 7 are sectional views of main parts similarly showing another embodiment. 1...Record, 2...Motor, 3
... Laser device, 7 ... Recording and reading section, 10 ... Optical converter, 11, 13 ...
Amplifier, 16, 25...Elastic frame, 17, 26
...... Support column, 19, 33... Lens holder, 23, 28, 32... Damper, 24,
29...Electromagnet, 30...Envelope, 3
1... Permanent magnet, 35... Drive coil, 36... Motional feedback coil, 37... Lens, 38... Penetrator 1
A40... Bimorph element.

Claims (1)

[Scope of Claims] 1. At least one pair of electromagnets arranged opposite to each other, and each center portion of another side surface that is disposed between the electromagnets and is orthogonal to the magnetic side surface that faces the electromagnets. An elastic frame body fixed relatively to the electromagnet and having an open end face, and a position controlled part attached to the elastic frame body so as to be located in the center thereof, By attracting the magnetic side surface portion of the elastic frame, the elastic frame is deflected and deformed, so that the position-controlled portion performs a predetermined linear movement in a direction opposite to the electromagnet. position control device. 2. In the position control device according to claim 1, the position control unit detects the deviation of the moving coil in order to perform motional feedback with the moving coil arranged in a magnetic field. A position-controlled member consisting of a detection section, a lens, and a cylindrical lens holder that integrally holds these movable coils, the detection section, and the lens is placed against the open end surface of the position-controlled section. A position control device characterized in that it is mounted so that it can move linearly in a vertical direction.