JPH0624012Y2 - Tilt control mechanism - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tilt control mechanism in an optical information recording disk playing device.

2. Description of the Related Art In an optical information recording disk playing device, when an information recording disk (hereinafter, simply referred to as a disk) has a warp due to a change with time or the like, the optical axis of an information detection light beam emitted from an optical pickup is set. On the other hand, when the information recording surface of the disc is tilted, the track pitch with the adjacent recording tracks is narrowed equivalently. Therefore, if the beam spot diameter on the information recording surface is kept constant, the pit information of the adjacent recording tracks It becomes susceptible to the influence and causes an increase in crosstalk. In order to improve such performance deterioration, the so-called tilt sensor detects the tilt of the information recording surface with respect to the optical axis of the information detecting light beam, and the optical axis of the information detecting light beam is recorded on the basis of this detection output. A tilt servo device is used that controls the tilt of the pickup so that it is always perpendicular to the surface.

In this tilt servo device, as a conventional example of the tilt control mechanism for controlling the tilt of the optical axis of the information detection light beam, the following three examples are known as typical ones. In the first conventional example, as shown in FIG. 5, an optical axis of an information detection light beam emitted from the pickup 1, that is, an optical axis of a light beam emitted from the pickup 1 with respect to a carriage 3 which is capable of linearly moving the pickup 1 along a guide axis 2. A structure in which the objective lens 4 is rotatably supported around a fulcrum P on the optical axis O, and the pickup 1 is rotated by a driving means (not shown) in accordance with the tilt angle of the optical axis O with respect to the information recording surface of the disk 5. Has become. In the second conventional example, as shown in FIG. 6, the pickup 1 is swingably supported with respect to the carriage 3 about a fulcrum P provided at a position away from the optical axis O, and a drive (not shown) is performed. The optical axis O with respect to the information recording surface of the disk 5
The pickup 1 is configured to swing in accordance with the inclination angle of the. In the third conventional example, as shown in FIG. 7, the pickup 1 is fixed to the carriage 3, and a guide shaft 2 for guiding the carriage 3 is supported at one end thereof so as to be swingable around a fulcrum P. The guide shaft 2 is swung according to the inclination angle of the optical axis O with respect to the information recording surface of the disk 5 by a driving means (not shown).

In these conventional examples, in the first conventional example, since the optical axis of the objective lens 4 and the rotation fulcrum P of the pickup 1 coincide with each other, the rotation of the pickup 1 causes the information recording surface of the disk 5 and the pickup 1 to rotate. The distance of the focus actuator fluctuates, and since the stroke of the focus actuator of the objective lens 4 has to cope with the variation of the distance, the load of the DC component of the focus actuator increases. is there. In the second conventional example, since the swing fulcrum P of the pickup 1 is offset with respect to the optical axis O of the objective lens 4, it is possible to reduce fluctuations in the distance between the information recording surface of the disk 5 and the pickup 1. It is possible, but not perfect. In the third conventional example, the tilting operation is performed almost in accordance with the actual distribution of the warp of the disk, and the variation in the distance from the disk 5 is small, but
Since the guide shaft 2 having a long dimension swings, there is a drawback that it requires a structural space.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks of the conventional ones, and it is possible to deal with a disc having a special warp by the stroke of the focus actuator within a certain range. It is an object of the present invention to provide a tilt control mechanism that does not require the space of.

In the tilt control mechanism according to the present invention, a pickup is rotated about a fulcrum on its optical axis by a carrier member which is connected to a linearly movable carriage so as to be movable or swingable in a direction perpendicular to an information recording surface of a disc. The first driving means allows the carrying member to move or swing with respect to the carriage in accordance with the distance between the information recording surface and the pickup, and the second driving means moves the optical axis of the optical axis relative to the information recording surface. The pickup is configured to rotate with respect to the carrier member according to the tilt angle.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view showing an embodiment of the present invention. In the figure, the optical pickup 1 is mounted on a carrier member 7 via a gear 6 fixed to one side surface of the optical pickup 1, and an optical axis of an information detecting light beam emitted from the pickup 1, that is, a fulcrum on an optical axis O of an objective lens 4. Is rotatably connected about. A worm 8 meshes with the gear 6, and the worm 8 uses a motor 9 carried on a carrying member 7 as a drive source. A carrying member 7 that rotatably carries the pickup 1.
Is movably coupled at one end to a guide shaft 10 carried on the carriage 3 so as to extend in the optical axis O direction, and a spiral shaft carried on the carriage 3 in parallel with the guide shaft 11. 11 is screwed into the other side end portion. Spiral axis 1
A gear 12 is fixed to one end of the gear 1, and a worm 13 is meshed with the gear 12. The worm 13 uses a motor 14 carried on the carriage 3 as a drive source. The carriage 3 is linearly movable by being movably connected to the guide shaft 2 whose both ends are fixed.

In such a configuration, the tilt of the information recording surface of the disc with respect to the optical axis O of the objective lens 4 is detected by a tilt sensor (not shown). Various types of tilt sensors are known, and for example, the one shown in Japanese Utility Model Laid-Open No. 59-168835 can be used. The detection output of this tilt sensor becomes the drive input of the motor 9. As a result, the pickup 1 is rotated around the fulcrum of the objective lens 4 on the optical axis O, and the inclination of the pickup 1 is adjusted so that the optical axis O is always perpendicular to the information recording surface of the disc. Be done. By adjusting the tilt of the pickup 1 about the fulcrum on the optical axis O, the distance between the information recording surface of the disc and the pickup 1 changes.
When the position of the pickup 1 in the direction perpendicular to the information recording surface is fixed, the variation of the separation distance appears as the variation of the DC component of the focus error signal, so that the objective lens 4 is displaced by the variation. The load on the focus actuator increases accordingly.

However, in the present invention, since the pickup 1 carried by the carrying member 7 is movable in the direction perpendicular to the information recording surface, the information recording surface and the pickup 1 are separated from each other due to the warp of the disc. By controlling the position of the pickup 1 by the motor 14 according to the variation in the distance, the variation in the separation distance can be corrected without burdening the focus actuator. As the drive input of the motor 14, the detection output of the focus error signal by detecting the variation of the direct current component is used, or a dedicated displacement sensor for directly detecting the displacement of the objective lens 4 is provided and the detection output of this sensor is used. be able to.

An example of the configuration of this displacement sensor 20 is shown in FIG. In this figure, an optical system 21 including an objective lens 4 is supported by a focus actuator 22 so as to be movable with respect to a pickup body 23 in the optical axis O direction. A shield plate 2 having a pinhole 24 at the lower end of the optical system 21.
5 is attached. A light emitting element 26 is arranged on one side of the shield plate 25, and is arranged on the opposite side in the optical axis O direction so as to receive the irradiation light emitted from the light emitting element 26 and passing through the pinhole 24 of the shield plate 25. A pair of light receiving elements 27a and 27b are provided. The light emitting element 26 and the light receiving elements 27a and 27b are positioned such that the light receiving amounts of the light receiving elements 27a and 27b are equal when the optical system 21 is in the neutral (neutral) position, as shown in FIG. 3 (A). Have a relationship. As a result, as shown in FIG. 3 (B), when the optical system 21 is displaced toward the disc side from the neutral position, the amount of light received by the light receiving element 27a on the disc side increases, and as shown in FIG. 3 (C). In addition, when the optical system 21 is displaced from the neutral position to the side opposite to the disc, the amount of light received by the light receiving element 27b increases. Therefore, the pair of light receiving elements 27a, 27a
An optical system 2 in which the polarity and level of this DC component includes the objective lens 4 is obtained by obtaining the difference between both outputs of b with the differential amplifier 28 and detecting the DC component with the low-pass filter 29.
The information corresponds to a displacement of 1.

This DC component is used as the drive input of the motor 14, and the focus actuator 22 is corrected by correcting the variation of the separation distance between the information recording surface and the pickup 1 caused by the warp of the disk by the position control of the pickup 1 in the optical axis O direction. Can always be maintained in the neutral position,
The load on the focus actuator 22 due to the DC component of the focus error signal can be reduced, and the drive current can be reduced accordingly.

FIG. 4 is a schematic perspective view showing another embodiment of the present invention,
In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals.
In the present embodiment, the carrying member 7 carrying the pickup 1 is swingably connected to the carriage 3 at one corner thereof, and is pinned in the slit 30 formed at the opposite side end thereof. Slide plate 3 with one end engaged through 31
The motor 14 coupled to the other end via the spiral shaft 33 serves as a drive source. Also,
The pickup 1 is rotatably coupled to the carrying member 7 about a fulcrum on the optical axis O of the objective lens 4 via a rotating plate 34 fixed to one side surface thereof. The rotating plate 34 constitutes a link mechanism together with a slide plate 37 whose one end engages with a slit 35 of its protruding portion via a pin 36, and uses the motor 9 connected to the other end via a spiral shaft 38 as a drive source. .

In such a configuration, the pickup 1 can be rotated about the fulcrum of the objective lens 4 on the optical axis O via the slide plate 37 and the rotating plate 34 by the motor 9 that uses the detection output of the tilt sensor as a drive input. Thus, the tilt of the pickup 1 is adjusted. On the other hand, the carrying member 7 is swung about a fulcrum provided apart from the optical axis O of the objective lens 4 by the motor 14 having the detection output of the displacement sensor 20 shown in FIG. The position of the pickup 1 in the direction perpendicular to the information recording surface is adjusted, and as a result, the variation of the separation distance between the information recording surface and the pickup 1 due to the warp of the disc is corrected.

Effect of the Invention As described above, according to the tilt control mechanism of the present invention, the pickup is carried out by the carrier member which is connected to the linearly movable carriage so as to be movable or swingable in the direction perpendicular to the information recording surface of the disc. It is rotatably supported about a fulcrum on the optical axis, and the tilt angle of the pickup is adjusted and the variation of the distance from the information recording surface is corrected independently by two drive systems. Therefore, even if the disk has a special warp, it can handle all the strokes of the focus actuator within a certain range, and since the guide shaft of the carriage is fixed, it requires a structural space. Nothing.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention, FIG. 2 is a configuration diagram showing an example of a displacement sensor, and FIGS. 3 (A) to 3 (C).
2 is an operation explanatory view of FIG. 2, FIG. 4 is a schematic perspective view showing another embodiment of the present invention, and FIGS. 5 to 7 are schematic configuration diagrams showing a conventional example. Description of symbols of main parts 1 ... Pickup, 3 ... Carriage 4 ... Objective lens, 7 ... Carrying member 9, 14 ... Motor, 20 ... Displacement sensor 21 ... Focus actuator 24 ... Shielding plate, 25 ...... Light emitting element 26a, 26b ...... Light receiving element 27 ...... Differential amplifier

Claims (1)

[Scope of utility model registration request] 1. A tilt control mechanism for controlling such that an optical axis of an information detecting light beam emitted from an optical pickup carried by a carriage which can move linearly is perpendicular to an information recording surface of an information recording disk. And a carrying member that is movably or swingably coupled to the carriage in a direction perpendicular to the information recording surface and that carries the pickup rotatably about a fulcrum on the optical axis.
First driving means for moving or rocking the carrying member with respect to the carriage according to the distance between the information recording surface and the pickup, and the first driving means for responding to the inclination angle of the optical axis with respect to the information recording surface. A tilt control mechanism comprising: a second drive unit for rotating the pickup with respect to the carrying member.