JPH05135369A - Optical disk and optical disk device - Google Patents

Abstract

PURPOSE:To facilitate switching of a rotational direction and to shorten moving time of an optical head in the case of switching a face by making the recording directions of information in a first face and a second face an inverse direction each other and making the end point of recording of the first face and the start point of recording of the second face in the vicinity of the outermost circumference together. CONSTITUTION:Information is recorded on a first face 9a of a double-sided optical disk 9 by making an inner periphery the start point and facing to an outer periphery clockwise and the information is recorded on a second face 9b by making the outer periphery the start point and facing to the inner periphery counterclockwise. Further, faces 9a and 9b are discriminated by the detection of the shift direction of the objective lens of the optical head or the moving direction of the optical head. Then, in the case of switching the recording and reproducing faces, necessity inversing the rotation of a spindle motor is eliminated and the movement of the optical head is settled from the outer periphery part of the face 9a to the outer periphery part of the face 9b. Thus, the faces 9a, 9b are detected easily and a waiting time for switching the faces is shortened remarkably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc on which information is recorded on both front and back sides by using optical means, or an optical disc on which information has already been recorded or a device for recording / reproducing this optical disc.

[0002]

2. Description of the Related Art The reproduction of a conventional optical disc and an optical disc device will be described.

First, as seen from the reproducing (recording) side of the optical disc 1, as shown in FIG. 6, information arranged in a pit row is recorded in a spiral shape in a clockwise direction from the inner circumference to the outer circumference. There is.

The optical disk 1 is placed on a turntable and rotated in the direction of arrow A, that is, counterclockwise. Information is reproduced on the optical disk 1 by an optical head (not shown) that is movable in the radial direction of the disk. This is performed by scanning the pit row 2 with a light spot.

From the pit row 2 of the optical disc 1 and the rotation direction of the arrow A, information is reproduced while an optical head movable in the radial direction moves from the inner circumference to the outer circumference.

There is a double-sided optical disk in which an optical disk 1 having an information pit row 2 formed on one surface is bonded, but the arrangement of the information pit row is the same on both surfaces.

To reproduce the information on the double-sided optical disk, as shown in FIG. 7, the first surface 3a of the double-sided optical disk 3 to be reproduced is set on the turntable 5 with the optical head 4 side, and the spindle motor 6 indicates the arrow. Information is read from the optical head 4 by rotating the optical head 4 in the direction indicated by A and moving the optical head 4 in the radial direction from the inner circumference to the outer circumference. When the information recorded on the first surface 3a of the double-sided optical disk 3 is completely reproduced up to the outer periphery and the information recorded on the second surface 3b on the opposite side is continuously reproduced, the rotation of the spindle motor 6 is temporarily stopped. The above-mentioned double-sided optical disk 3
Take out from the turntable 5, turn it over, and set it again on the turntable 5. Then, in the same manner as the reproduction of information on the first surface 3a of the double-sided optical disk 3, the optical head 4
From, the information on the second surface 3b is read from the inner circumference toward the outer circumference.

As described above, when the double-sided optical disk 3 is manually inverted and the information on both sides 3a and 3b is reproduced, it takes a lot of time to reverse the double-sided optical disk 3, and the spindle motor is required to reverse the double-sided optical disk 3. It is necessary to wait for 6 to stop, to take out the double-sided optical disk 3 and turn it over and set it on the turntable 5, and to restart the spindle motor 6 and stabilize the rotation.

In particular, when playing software such as movies and live stages on a laser disc, it takes time and time to move from the first side to the second side of the disc. It is not desirable because it will be divided and aroused.

Therefore, in order to shorten the transition time from the first surface 3a to the second surface 3b, a double-sided continuous reproducing apparatus has been proposed. FIG. 5 is a conceptual diagram showing an example of a continuous reproducing apparatus for a double-sided optical disk, and a schematic procedure for reproducing recorded information will be described below.

In FIG. 5, the reproduction of the information recorded on the first surface 3a of the double-sided optical disk 3 is performed in the same manner as described above. After the reproduction of the first surface 3a is completed, the optical head 4
The optical head 4 is provided on the second surface 3b side along the guide rail 7 formed in a U shape from a to the second surface 3b.
It moves to a, 4-b, 4-c, and moves to 4-d which is the innermost circumferential position of the second surface 3b.

The optical head 4 has the first surface 3a to the second surface 3
While moving to b, the spindle motor 6 reverses its rotation. As described above, this is the first surface 3a of the double-sided optical disk,
Since information pit rows are recorded in the clockwise direction from the inner circumference to the outer circumference on both the second surface 3b and the information is reproduced along this information pit row, the reproduction of the second surface 3b is the reverse of the reproduction of the first surface 3a. Directional disc rotation is required.

[0013]

With the double-sided continuous reproducing apparatus for double-sided optical disk as described above, it is necessary to manually take out the double-sided optical disk from the apparatus at the time of switching the reproducing surface, turn over the double-sided optical disk, and set it again in the apparatus. Free time is no longer needed.

However, (i) the start-up time until the spindle motor 6 for the reverse rotation of the double-sided optical disk 3 is stably rotated, (ii) the optical head 4 is moved from the outer circumference of the first surface 3a to the second surface of the double-sided optical disk 3. It takes time to move to the inner circumference of 3b.

In an ordinary apparatus, the above items (i) and (ii) are performed in parallel, so that the time required for both operations is not added, and in fact, the spindle motor 6 of item (i) is actually added.
It takes a longer time to reverse the
It takes 10 seconds or more from the end of the reproduction of the first surface 3a to the start of the reproduction of the second surface 3b.

As described above, the conventional optical disk and optical disk apparatus have a drawback that a long time is required when switching the recording / reproducing surface.

[0017]

In order to solve the above problems, an optical disk and an optical disk apparatus according to the present invention are provided.
Information is spirally recorded on both front and back surfaces of the first surface and the second surface by using an optical head as an optical means, or in an optical disk that has already been recorded, the direction of information recording is first.
The surface and the second surface are opposite to each other (Claim 1).

Further, the end point of the information recording on the first side is near the outermost circumference of the effective recording area, and the start point of the information recording on the second side is near the outermost circumference ( Claim 4).

[0019]

In the optical disk and the optical disk device according to the present invention, one side of the double-sided optical disk has a spiral direction for recording information in the clockwise direction and the other side has a counterclockwise direction for recording or reproducing. When the surfaces are switched, it is not necessary to reverse the rotation of the spindle motor, and the surface switching time is only the time for the optical head to move from the first surface outer peripheral portion to the second surface inner peripheral portion.

Further, since the start point of recording the information on the second surface of the double-sided optical disk is near the outermost circumference and the spiral recording is performed in the counterclockwise direction toward the inner circumference, the reverse rotation of the spindle motor is unnecessary. In addition, since the movement of the optical head is required only from the outer peripheral portion of the first surface to the outer peripheral portion of the second surface, the waiting time for surface switching is significantly reduced.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk and an optical disk device of the present invention will be described with reference to the drawings.

In the optical disc of the present invention, the recording start point and recording direction of information are as shown in FIGS. 1 and 2, for example. In FIG. 1, the first surface 8a of the double-sided optical disk 8 is shown.
The information is recorded clockwise from the inner circumference toward the outer circumference, and the second surface 8b is recorded counterclockwise from the inner circumference toward the outer circumference.

In FIG. 2, the first side of the double-sided optical disk 9 is shown.
On the surface 9a, information is recorded clockwise from the inner circumference toward the outer circumference, and on the second surface 9b, information is recorded from the outer circumference toward the inner circumference in the counterclockwise direction. The information recording direction is the case where each side of the double-sided optical disks 8 and 9 is viewed from the optical head, and the rotation direction of the double-sided optical disks 8 and 9 is as shown by arrows A and B in FIGS. is there.

Next, a case where the optical disk 8 is driven by an optical disk device will be described with reference to FIG. Normally, for example, the double-sided optical disk 8 shown in FIG. 2 is placed on the turntable so that the first surface 8a faces downward, that is, the turntable 5, and the double-sided optical disk 8 is viewed from the optical head by the spindle motor 6. Rotate clockwise,
As a result, the information on the first surface 8a is detected and reproduced by the optical head 4 from the inner circumference toward the outer circumference.

During this reproducing operation, the double-sided optical disk 8 is erroneously
The case where the second surface 8b of the above is set downward will be described below. In this case, the optical head 4 reads the information in the clockwise direction from the outer circumference to the inner circumference, even though the information is recorded in the counterclockwise direction from the inner circumference on the second surface 8b toward the outer circumference. As a matter of course, the information cannot be reproduced correctly.

An example of a method for detecting the above-mentioned incorrect double-sided optical disk setting will be described with reference to FIG. 3. In order for the optical head 4 to accurately irradiate a light spot on an information track, the objective lens 10 is used for information. It has an actuator 11 that is driven in the direction perpendicular to the tracks of the pit train. Of course, the actuator 11 has a structure that can be driven in the rotation axis direction of the double-sided optical disk 8, but it is omitted here. Further, the light spot emitted from the optical head 4 is the first surface 8a or the second surface 8b of the double-sided optical disk 8.
The optical head 4 outputs a track error signal (TES) indicating whether or not the track is correctly tracked. The track error signal TES is applied to the actuator 11 via a servo circuit 15 composed of an amplifier 12, a phase compensation circuit 13, an actuator drive circuit 14, etc., and a servo is applied so that the light spot always follows the track. ..

On the other hand, when the optical head 4 is moved, the DC offset detection circuit 16 detects the DC offset generated on the servo signal, and the head feed circuit 18 keeps the DC offset at zero or below a certain level. It is performed by a feeding mechanism (not shown). Reference numeral 17 is a polarity discriminating circuit.

Assuming that the information on the first surface 8a or the second surface 8b of the double-sided optical disk 8 is recorded from the inner circumference to the outer circumference, a state where the light spot is made to follow the track is shown in FIG. It will be explained based on. Figure 4 (a) shows
The state where the objective lens 10 is not shifted with respect to the double-sided optical disc 8 is shown, and the track error signal TES has a swell that corresponds to the eccentricity of the disc with respect to the time axis (t) about zero. Since the information is recorded from the inner circumference to the outer circumference of the double-sided optical disk 8, the objective lens 10 is gradually shifted toward the outer circumference as shown in FIG. 4 (b). The track error signal TES waveform at this time has a DC offset.

The polarity of the DC offset generated by the shift of the objective lens 10 depends on the shift direction of the objective lens 10. In FIG. 4B, the objective lens 10 is shifted to the outer peripheral side, and as a result, the track error signal TES has a positive DC offset.
A negative DC offset occurs when 0 shifts inward. Therefore, the DC in the track error signal TES
The moving direction of the objective lens 10 can be determined by the polarity of the offset.

When a DC offset occurs in the track error signal TES as shown in FIG. 4B, the optical head 4 sends the optical head 4 to the outer peripheral side so that the DC offset becomes zero. That is, as shown in FIG. 4 (a) to FIG. 4 (c), the operation of the apparatus is to shift the objective lens → DC to TES.
The procedure is as follows: offset generation → optical head feed → elimination of objective lens shift.

In the structure of claim 2, when the setting of the double-sided optical disk 8 is correct, the objective lens 10 and the optical head 4 move from the inner circumference to the outer circumference. When the setting of the double-sided optical disk 8 is incorrect, the objective lens 10 and the optical head 4 move in the inner circumferential direction, so that the determination can be made from the DC offset of TES due to lens shift or the polarity of the optical head drive signal. When a setting error is detected, the rotation of the double-sided optical disk 8 is maintained as it is, the optical head 4 is moved to the opposite side, and reproduction is performed from the inner circumference, whereby a normal reproduction operation is performed.

In the structure of claim 3, the detection of the setting error of the double-sided optical disk is substantially the same as the above, and therefore the description thereof will be omitted.

If the first and second surfaces of the double-sided optical disk 9 are set in the optical disk device by mistake, the reverse reproduction is naturally performed and the information reproduction cannot be performed correctly. In this case, since it cannot be determined in the moving direction of the objective lens, a software determination is performed. That is, the setting error of the disk is detected by the error generated when the information cannot be read correctly. Specifically, when a so-called disc index called a lead-in area is first read at the time of reproducing a disc, if the reproduction direction is wrong, the reading becomes impossible. The disc is judged to be unreproducible and the reproducing operation is stopped.

To return to the correct reproduction, the optical head may be moved to the opposite side and the disc rotation may be reversed. The recording direction of information on the double-sided disc is the first in the embodiment.
Although the disk whose surface is recorded as a clockwise spiral has been described, the present invention is not limited to this. That is, even if the first surface is counterclockwise, if the rotation direction of the spindle motor of the optical disk device is clockwise and the information recording direction of the second surface is the corresponding direction, information recording / reproduction is performed in the same manner. Can be done. Further, the example of the double-sided continuous reproduction apparatus as the optical disk apparatus has been described, but since the first side and the second side of the disk can be discriminated as described above, the conventional single-sided reproduction type apparatus can be handled without any problem.

[0035]

As described above, in the double-sided continuous reproducing apparatus or double-sided continuous recording apparatus, the inventions of claims 1, 2, 3, and 4 are directed to the first and second surfaces of the double-sided optical disk in the direction of rotation of the disk. There is no need to switch.

According to the second aspect of the invention, since the starting point of the information is located in the area of the inner circumference of the disc where the surface wobbling is small, the pulling of the focus servo becomes reliable.

According to a third aspect of the present invention, there is provided a first double-sided optical disc.
When the disc is set in the direction of reproducing (recording) the second surface by mistake for the second surface, it is determined that it is the second surface at the outermost circumference, and the optical head is moved to the outermost circumference of the first surface.
At this time, the moving distance of the optical head is the shortest, and the reproducing / recording operation can be performed in a short time.

According to a fourth aspect of the present invention, the movement of the optical head after the reproduction / recording of the double-sided optical disk is completed is the shortest distance from the outermost circumference of the first surface to the outermost circumference of the second surface, and the surface switching is short. Can be done with.

According to the fifth and sixth aspects of the present invention, the surface of the double-sided optical disc can be easily detected without adding a new mechanism to the conventional device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a recording direction of an optical disc of the present invention.

FIG. 2 is an explanatory diagram showing another recording direction of the optical disc of the present invention.

FIG. 3 is a block circuit diagram of an optical disk device of the present invention.

4 (a), (b) and (c) show the relationship between the track error signal (TES) and the DC offset accompanying the shift of the optical head in the state where the optical spot is made to follow the track of the disk. FIG.

FIG. 5 is a schematic configuration diagram of a guide rail of an optical head implemented in the optical disk device of the present invention.

FIG. 6 is an explanatory diagram showing a recording direction of a conventional optical disc.

FIG. 7 is a schematic configuration diagram of a conventional optical disc device.

[Explanation of symbols]

 3,8,9 Double-sided optical disk 4 Optical head 7 Optical head guide rail 11 Actuator 15 Servo circuit 16 DC offset detection circuit 17 Polarity determination circuit 18 Head feed circuit

Claims (6)

[Claims] 1. Information is spirally recorded on both front and back surfaces of a first surface and a second surface by using optical means, or in an optical disk that has already been recorded, the recording direction of the information is first.
An optical disc having a first surface and a second surface which are opposite to each other. 2. The starting points for recording the information are the first surface and the second surface.
2. The optical disc according to claim 1, wherein both surfaces are near the innermost circumference of the effective recording area. 3. The starting points for recording the information are the first surface and the second surface.
The optical disk according to claim 1, wherein both surfaces are near the outermost circumference of the effective recording area. 4. The end point of recording information on the first side is near the outermost periphery of the effective recording area, and the start point of recording information on the second side is near the outermost periphery. The optical disc described in. 5. The optical disk device for recording or reproducing the optical disk according to claim 2 or 3, wherein the discriminating means for the first surface or the second surface is a shift direction of the objective lens of the optical head or a moving direction of the optical head. An optical disk device characterized by detection, 6. The optical disk device according to claim 5, wherein a DC offset level on a tracking servo signal is used as a means for detecting the direction of the objective lens.