JPH06131681A - Tilt servo device - Google Patents

Abstract

PURPOSE:To reduce the number of components by placing a single optical sensor on a supporting based on one side, and detecting the inclination of a disk by the optical sensor. CONSTITUTION:A line sequential color video signal is recorded distributedly on a first disk 3a in which a spiral track is extended in a clockwise direction and a second disk 3b in which it is extended in a counterclockwise direction on a turntable 2 driven by a spindle motor 1. The disk 3 formed by adhering those disks 3a, 3b is loaded, and first and second pickups 10, 11 are provided on the surface and back plane of the disk 3. Both pickups are supported with supporting bases 6, 7 advancing/retreating in a diameter direction so as to be inclined. When a motor shaft is rotated by driving a first tilt motor 12, a rotary lever 8 rotated, which makes the inclination of the first pickup 10 possible for the disk 3 to be changed, and also, makes that of the second pickup possible 12 for the disk 3 to be changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a disc player which reproduces both sides of a disc with two pickups, and when the discs are warped, the optical axis of each pickup is orthogonal to each face of the disc. The present invention relates to a tilt servo device.

[0002]

2. Description of the Related Art In a player which optically reproduces a signal from a disk having a relatively large diameter such as a laser disk, two photodiodes are light emitting diodes as disclosed in Japanese Patent Publication No. 63-22369. The tilt sensors arranged on both sides of the pickup are fixed on the support base on which the pickup is supported, and the light emitting diode emits light with the objective lens of the pickup facing the disc. The reflected light reflected by each photodiode is detected by each photodiode, and the difference between the two received light outputs is detected as an error voltage proportional to the tilt of the disk with respect to the optical axis of the objective lens of the pickup, and this error voltage is applied to the tilt motor. By tilting the pickup in the same direction as the disc until the error voltage becomes zero, the optical axis of the pickup By perpendicular to the disk, the tilt servo apparatus crosstalk interference is removed is essential.

As a kind of video disc player, the present applicant has previously filed Japanese Patent Application No. 2-114077.
The following suggestions are made. That is, a line-sequential color video signal is distributed and recorded at a line period on a first disc having spiral tracks extending in the clockwise direction and a second disc extending in the counterclockwise direction, and these discs are bonded together. To form one disc, and at the time of reproduction, separate pickups are arranged on the front and back surfaces of the disc mounted on the single turntable, respectively, and the reproduction signals obtained by simultaneous reproduction on both sides are combined to create the original disc. A high-resolution color video signal is created.

[0004]

As described above, when both sides of a disc are reproduced simultaneously by two pickups, the above-mentioned tilt servo device is required for each pickup, and as a result, the tilt sensor also has two units. You need one.

[0005]

Means for Solving the Problems First and second support bases that linearly advance and retreat in the radial direction of the disk while supporting first and second pickups for reading signals from the front and back surfaces of the disk. A first and a second tilt mechanism for inclining the second pickup by an arbitrary angle with respect to the first and second support bases, and one light emitting element mounted on one of the two support bases, and this light emitting element. 2 symmetrically arranged with respect to
An optical sensor including a plurality of light receiving elements, an error signal creating means for creating an error signal corresponding to a difference in light receiving level of both light receiving elements, and a servo circuit for supplying the error signal to the first and second tilt mechanisms. The first pickup is tilted in the inner circumferential direction of the disc, and the second pickup is tilted in the outer circumferential direction of the disc.

[0006]

Since the present invention is constructed as described above, one optical sensor is placed on one of the support bases, the tilt of the disk is detected by this optical sensor, and the sensor outputs are picked up by both pickups. It can be used for tilt servo of
One optical sensor can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view of an embodiment of the present invention. On the turntable 2 driven by the spindle motor 1, line-sequential color video signals are lined on a first disk 3a having a spiral track extending clockwise and a second disk 3b having a counterclockwise extending line, respectively. A disc 3 which is recorded and distributed in a cycle and formed by bonding both discs to each other is mounted, and the back surface and the front surface of the disc 3, that is, the first and second discs 110 and 110, respectively.
1 is provided.

Each of the first and second pickups 10 and 11 is tiltably supported by support bases 6 and 7 which can be moved back and forth in the radial direction of the disk by a drive mechanism (not shown).
Here, the guide portions 6b and 7b are fitted to the guide rails 4 and 5 arranged in parallel to the disc radial direction to guide the movement.

The method of supporting each pickup on the support base will be described in more detail. The rotating levers 8 and 9 are made to move in a clock or a time by the protruding pins 6a and 7a formed on the support bases 6 and 7 so as to be parallel to the disc. The first and second pickups 10 and 11 are fixed to the turning levers 8 and 9 so as to be pivotable counterclockwise. Further, the first and second tilt motors 1 in which the screw holes of the stoppers 8a and 9a fixed to the tips of the respective rotation levers are fixed to the support bases 6 and 7.
Screw portions 12a formed on the motor shafts 2 and 13;
The positions of the rotation lever and both pickups are defined by screwing the screw 13a. In addition, the tilt motor 12,
The shapes of 13 and the screw portions 12a and 13a are exactly the same.

Here, when the first tilt motor 12 is driven to rotate the motor shaft, the stopper 8a moves up or down, the rotary lever 8 rotates, and the inclination angle of the first pickup 10 with respect to the disc 3 can be changed. Further, when the second tilt motor 13 is driven and the motor shaft rotates, the stopper 9a moves up or down, the rotating lever 9 rotates, and the inclination angle of the second pickup 11 with respect to the disc 3 can be changed.

Further, both tilt motors can be normally or reversely rotated according to the polarity of the drive signal inputted together, and when the drive signal has a positive polarity, it normally rotates and when it has a negative polarity, it reverses. By the way, since the second tilt motor 13 is arranged upside down with respect to the first tilt motor 12,
The direction in which the stopper 8a is moved away from the motor body during the normal rotation of the first tilt motor 12 means that the stopper 8a is raised,
Although the turning lever 8 is turned counterclockwise,
The direction in which the second tilt motor 13 moves the stopper 9a away from the motor body means that the stopper 9a is lowered and the rotation lever 9 is rotated clockwise.

Further, only the first pickup 10 is shown in FIG.
As shown in, the tilt sensor -14 is fixed near the objective lens 10a. In this tilt sensor, a light emitting diode 25 is fixed in the center, and a pair of photodiodes 16a and 16b are arranged around the light emitting diode in the disk radial direction. When the light emitting diode 25 emits light, the light is emitted from the disk. The reflected light is reflected on the back surface, and the reflected light is received by each of the photodiodes 16a and 16b. If the optical axis of the objective lens 10a is orthogonal to the back surface of the disc, the amount of light received by the photodiode is uniform, but if the optical axis is not orthogonal, imbalance occurs in the amount of light received.

The light receiving outputs P1 and P2 of the photodiodes 16a and 16b are respectively supplied to the comparing circuit 15, and the difference between the two light receiving outputs, P1-P2, is output as an error signal, and the phase compensation circuit 16 performs phase compensation. Amp 1
After being amplified with a predetermined gain at 7, the first tilt motor 1
2 is supplied.

The first tilt motor 12 determines the forward and reverse rotation directions according to the polarity of the error signal, and the rotation amount according to the absolute value of the error signal level. For example, in FIG.
As shown in FIG. 3, when the outer peripheral side of the disk 3 is warped downward, more reflected light reaches the photodiode 16a side on the inner peripheral side, and P1> P2, and the error signal is positive. And reverse the first tilt motor 12,
The stopper 8a is lowered to rotate the rotary lever 8 in the clockwise direction, and the amount of this rotation is proportional to the difference between the two received light amounts, and the larger the difference, the larger the tilt amount of the first pickup. Along with this, the first pickup 10 is rotated clockwise to the position of the chain line in FIG. 3, and the optical axis of the objective lens 10a is orthogonal to the back surface of the disc. In this orthogonal state, the error signal is zero. become.

Further, the error signal is supplied to the second tilt motor 13 after the polarity is inverted by the inversion circuit 18. This second tilt motor 13 is also the first tilt motor 1
As in the case of 2, the rotation direction of forward rotation and reverse rotation is determined by the polarity of the error signal, and the rotation amount is determined by the absolute value of the error signal level. That is, as described above, when the outer peripheral side of the disk is warped downward and P1> P2,
The reverse error signal has a reverse polarity and the second tilt motor 13
In reverse, the stopper 9a is lowered, and the second pickup 11 is rotated clockwise to the position of the chain line in FIG. 3 to make the optical axis of the objective lens 12a orthogonal to the disk surface.

As described above, by adjusting the tilts of both pickups by the same amount with the single tilt sensor, the optimum tilt servo is possible because both pickups are located at the same radial position on each surface of the disk. Since the disc is being reproduced, the inclination angle of the disc due to the surface warp at each reproduction position can be considered to be substantially equal on the front surface and the back surface of the disc.

In this way, while the tilt angle is adjusted so that the optical axis is orthogonal to each surface of the disk, both pickups hold the position of plane symmetry with respect to the disk so that each surface of the disk is always opposed from the inner peripheral side to the outer peripheral direction. And simultaneously reproduce the signal.
During this reproduction, the reproduction positions of both pickups are the same radial position of the disc. The read signals simultaneously reproduced from the respective pickups are input to the reproduction signal processing circuit, and the line-sequential color image signals distributed and recorded are FM-demodulated, and then A / D converted and temporarily stored in each memory as digital values. By retaining and processing each of the retained data according to a predetermined rule, the line-sequential color image signals which are substantially divided and recorded on both sides are combined to create the original color image signal. The color video signal thus created has a wider band of the video signal as compared with the case of recording only on one side, and becomes a high resolution video signal.

In the above-described embodiment, the tilt sensor 14 is mounted on the lower first support base 6, but is mounted on the upper second support base 7 to output an error signal to the second tilt motor 13. Moreover, there is no problem even if the reverse error signal is supplied to the first tilt motor 12. Further, although the rotation centers of both pickups are the projecting pins 6a and 7a, it is possible to set the rotation center on the optical axis of the objective lens of the pickup by another configuration.

[0019]

As described above, according to the present invention, a single optical sensor is placed on either one of the support bases, the tilt of the disk is detected by this optical sensor, and the sensor outputs are picked up by both pickups. It can be used for the tilt servo, and the number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an overall outline of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a first pickup according to an embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the tilt servo of the present invention.

[Explanation of symbols]

 3 Disc 10 First Pickup 6 First Support Base 11 Second Pickup 7 Second Support Base 8 Rotating Lever 9 Rotating Lever 14 Tilt Sensor 16a Photodiode 16b Photodiode 25 Light Emitting Diode 15 Comparison Circuit

Claims (1)

[Claims] 1. A first for reading a signal from the surface of a disk
A pickup, a first support base that linearly advances and retreats in the radial direction of the disc while supporting the first pickup, and a first inclination that inclines the first pickup with respect to the first support base by an arbitrary angle. A second means for reading a signal from the back surface of the disk while facing the first pickup with the disk interposed between the driving means and the driving means;
A pickup, a second support base that linearly advances and retreats in the radial direction of the disc while supporting the second pickup, and a second inclination that inclines the second pickup with respect to the second support base by an arbitrary angle. Drive means, a light-emitting element placed on either one of the both support bases and irradiating light to the disk, and a light-emitting element that is symmetrically arranged around the light-emitting element and is emitted from the light-emitting element. An optical sensor including a pair of light receiving elements that receives the light reflected by the disk, an error signal creating unit that creates an error signal corresponding to the difference in the light receiving levels of the two light receiving elements, and the error signal for the first and second error signals. A servo circuit for supplying to the two tilt drive means is provided, wherein the first pickup is tilted in the inner circumferential direction of the disk, and the second pickup is connected to the disk. The tilt servo apparatus characterized by tilting in the circumferential direction.