JPH0624013Y2 - 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 disc playing device, when an information recording disc (hereinafter, simply referred to as a disc) 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 made constant, the bit 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 provides a tilt control mechanism capable of dealing with a disc having a special warp without burdening the focus actuator. With the goal.

The tilt control mechanism according to the present invention allows a pickup to be rotated in a plane including its optical axis by a carrier member that is movable or swingably coupled to a linearly movable carriage in a direction perpendicular to an information recording surface of a disc. Supported on the
The configuration is such that the tilt angle of the pickup and the variation in the distance from the information recording surface are independently corrected by two drive systems, and the variation in the distance between the objective lens included in the pickup and the information recording surface is adjusted. It is characterized by detecting and correcting the variation of the separation distance according to the detection output.

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 rotatable on a carrying member 7 via a gear 6 fixed to one side surface thereof, that is, an optical axis of an information detecting light beam emitted from the pickup 1 (optical axis O of an objective lens 4). ) Is rotatably coupled in a plane parallel to the plane of rotation of the gear 6 fixed to the carrying member 7. 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. The carrying member 7 rotatably carrying the pickup 1 is movably connected at one end to a guide shaft 10 carried on the carriage 3 so as to extend in the optical axis O direction, and the guide shaft 10 In parallel with, the spiral shaft 11 carried on the carriage 3 is screwed at the other end. A gear 12 is fixed to one end of the spiral shaft 11, 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.

The pickup 1 has a built-in displacement sensor 20 for directly optically detecting a change in the distance between the objective lens 4 and the information recording surface. An example of the configuration of this displacement sensor 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 25 having a pinhole 24 is attached to the lower end of the optical system 21. 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. These light emitting element 26 and light receiving element 27a,
As shown in FIG. 3 (A), the reference numeral 27b denotes the light receiving elements 27a, 2a when the optical system 21 is in the neutral (neutral) position.
The positional relationship is such that the respective light receiving amounts of 7b are equal. As a result, as shown in FIG. 3 (B), the optical system 2
When 1 is displaced to the disk side from the neutral position, the amount of light received by the light receiving element 27a on the disk side increases, and as shown in FIG. 3C, the optical system 21 is displaced to the side opposite to the disk from the neutral position. When this happens, the amount of light received by the light receiving element 27b increases. Therefore, the difference between the outputs of the pair of light receiving elements 27a and 27b is calculated by the differential amplifier 2
8 and the DC component is detected by the low-pass filter 29, the polarity and level of this DC component becomes information corresponding to the displacement of the optical system 21 including the objective lens 4.

In this embodiment, the displacement sensor 20 is attached to the pinhole 24.
However, the present invention is not limited to this, and a so-called knife edge, slit or the like may be used to obtain the difference in the received light distribution. Is also possible.

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 via the worm 8 and the gear 6, 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. The adjustment of the tilt of the pickup 1 causes the distance between the information recording surface of the disc and the pickup 1 to change. When the position of the pickup 1 in the direction perpendicular to the information recording surface is fixed, the distance changes. Since the change appears as a change in the DC component of the focus error signal, the objective lens 4 is displaced by the change, and 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. That is, the DC component of the detection output of the displacement sensor 20 is used as the drive input of the motor 14, and the optical axis O of the pickup 1 is used.
The focus actuator 22 can always be maintained in the neutral position by correcting the variation in the separation distance between the information recording surface and the pickup 1 caused by the warp of the disc by the position control in the direction, so that the focus due to the DC component of the focus error signal is focused. Actuator 2
The load of 2 can be reduced, and the drive current can be reduced accordingly.

In the above embodiment, the case where the carrying member 7 is movable in the direction perpendicular to the information recording surface of the disk has been described, but the carrying member 7 can be swung in the direction perpendicular to the information recording surface of the disk. It can also be configured. The structure is shown in FIG. In FIG. 4, a carrying member 7 carrying the pickup 1 is swingably connected to the carriage 3 at one corner thereof, and a pin 31 is provided in a slit 30 formed at a side end portion on the opposite side thereof. A motor 14 that forms a link mechanism with the slide plate 32 whose one end is engaged via the motor 14 and is coupled to the other end via the spiral shaft 33.
Is the driving source. Further, the pickup 1 is rotatably coupled to the carrying member 7 via a rotary plate 34 fixed to one side surface thereof. The rotating plate 34 has a slide plate 37 whose one end engages with a slit 35 of the protruding portion through a pin 36.
Together with this, a link mechanism is configured, and the motor 9 coupled to the other end through the spiral shaft 38 is used as a drive source.

In such a configuration, the pickup 1 can be rotated in the plane parallel to the rotation surface of the rotation plate 34 via the slide plate 37 and the rotation plate 34 by the motor 9 using 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 in a plane including the optical axis, and the driving system of two systems independently adjusts the tilt angle of the pickup and corrects the variation of the separation distance from the information recording surface. Therefore, it is possible to deal with a disc having a special warp without burdening the focus actuator.

Further, since the variation of the separation distance of the objective lens with respect to the information recording surface is directly detected, the variation of the separation distance can be accurately detected and the detection sensor can prevent the collision of the objective lens with the disk. It is also possible to obtain the effect that it can be used for detecting malfunctions.

[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 22 ... Focus actuator 25 ... Shielding plate, 26 ...... Light emitting element 27a, 27b ...... Light receiving element 28 ...... 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 for movably or swingably coupled to the carriage in a direction perpendicular to the information recording surface and carrying the pickup so as to be rotatable in a plane including an optical axis thereof; Detecting means for detecting a change in distance between the included objective lens and the information recording surface, and first driving means for moving or swinging the carrying member with respect to the carriage in accordance with a detection output of the detecting means. And second drive means for rotating the pickup with respect to the carrier member according to the inclination angle of the optical axis with respect to the information recording surface. Tilt control mechanism for the butterflies.