JPH0697505B2 - Information recording method for reading information on a disk - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for reading recorded information from an information recording disc, and more particularly to a method for reading recorded information from an information recording disc (hereinafter, simply referred to as a disc) such as a digital audio disc.

BACKGROUND ART A conventional recorded information reading method controls a position of an information detection point of a pickup in a radial direction of a disc by a tracking servo device and, at the same time, drives the disc to rotate so that the information detection point is relative to a recording track in its extension direction. In this method, the information recorded together with the address information is read by manually moving it.

In such a conventional method, the tracking servo device is disturbed due to a scratch on the disk and a so-called track jump occurs, and the information detection point is in a direction opposite to the relative movement direction with respect to the disk, that is, the inner circumferential direction of the disk, for example. If it is mistakenly moved, the loop enters such that the same information is repeatedly read, and the obtained reproduced sound or the like becomes uncomfortable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a recording information reading method for an information recording disc, which can favorably read the recording information even if the disc has a scratch or the like. With the goal.

A method for reading recorded information from an information recording disc according to the present invention is
When a track jump occurs, the information detection point is moved from the jump destination position to the address position immediately before the jump by the track jump operation, and the track jump occurs again at the same position.
Moreover, when the jump destination is approximately the same position, the information detection point is moved by a predetermined distance from the position corresponding to the immediately preceding jump address by a relative movement in the track extension direction, and then information detection is performed. It is characterized in that the point is moved to a position a predetermined distance behind the position corresponding to the address value immediately before the jump by the track jump operation, and then the normal reproduction operation is started.

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

FIG. 1 is a block diagram showing an example of, for example, an optical disc reproducing apparatus to which the recording information reading method according to the present invention is applied. In the figure, a laser beam emitted from, for example, a laser diode 2 in a pickup 1 passes through a prism 3, a tracking mirror 4, an objective lens 5 and the like to become spot light (information detection point), and a recording track (pit Example) 7 is irradiated. The reflected light of the spot light passes through the objective lens 5, the tracking mirror 4, and the prism 3 and enters a so-called four-divided detector 8 including a photodiode or the like built in the pickup 1. The relaxation output of the 4-division detector 8 is used as a read RF signal.
It is supplied to the demodulator 10 via the RF amplifier 9,
Data demodulation circuit 11 and data processing circuit 20 after demodulation by
Is supplied to. The data extraction circuit 11 extracts address information from the demodulated output, and the address information is stored in the controller.
Supplied to 12.

Further, in the data processing circuit 20, the output data of the demodulator 10 is temporarily stored in the data memory 21 after being subjected to processing such as deinterleaving, error detection, correction and correction. The data stored in the data memory 21 is read by a clock signal of a constant cycle from a clock generation circuit (not shown), and converted into an analog signal in a D / A (digital / analog) converter 22. This analog signal is LP
It is output as an audio signal via an F (low-pass filter) 23.

Each output of the 4-division detector 8 is also supplied to the tracking error signal generation circuit 13. As a method of generating the tracking error signal, there is a so-called 1-beam method, a 3-beam method, or the like, and the 1-beam method also includes a so-called push-pull method, a heterodyne method, or the like. As shown in FIG. 2, the tracking error signal generated by the tracking error signal generation circuit 13 by these well-known generation methods has a so-called S-shaped curve characteristic of zero crossing at the center of the recording track 7, By being supplied to the drive coil 15 of the tracking mirror 4 via the mirror drive circuit 14, the mirror 4 is rotationally driven.

Reference numeral 16 denotes a slider motor that mounts the pickup 1 and drives a slider (not shown) that is movable in the disk radial direction. The motor 16 is driven and controlled by a motor drive circuit 17. The motor drive circuit 17 detects the tilt angle of the tracking mirror 4 based on the output of the mirror drive circuit 14, and the slider motor 16 drives the slider 1 in the disk radial direction so that the tilt angle is zero, that is, the tracking mirror 4 is in the neutral position. Position control.
The mirror drive circuit 14 and the motor control circuit 17 are also drive-controlled by a drive signal issued from the controller 12. The track pulse generation circuit 18 generates one pulse each time the spot light crosses the recording track 7 based on the tracking error signal shown in FIG. 2 when the pickup 1 moves in the disk radial direction, and sends it to the controller 12. . The controller 12 is composed of a micro computer including a processor, a ROM, a timer and the like. In this controller 12, the processor performs various controls in cooperation with the RAM 24 according to a program stored in advance in the ROM and based on the flowchart of FIG.

Next, an operation procedure of an example of the recorded information reading method according to the present invention, which is executed by the processor of the controller 12, will be described with reference to the sequence diagram of FIG. 4 and along the flowchart of FIG.

Information recording discs, for example, so-called compact discs, record information indicating absolute time from the innermost disc to the current position and information indicating absolute time from the innermost disc to the beginning of each song as address information. There is.

Now, when the play operation is performed by the execution of the main routine and the address spot is read, that is, the beam spot of the pickup 1 reaches the point, and the address information is read, the processor reads the current value of the address information, that is, the address information read at the point. Is compared with the previous value of the address information, that is, the value corresponding to the previously read address information (steps 1 and 2). If it is determined in step 1 that the current value of the address information matches the previous value, the processor immediately restarts execution of the main routine through step 3. In step 3, it is determined whether or not a loop flag (see step 17) described later is set, and if it is not set, the process returns to the main routine. When it is determined in step 2 that the current value of the address information matches the value obtained by adding 1 to the previous value, the processor proceeds to step 4 and sets the current value of the address information to the A ₁ address of the RAM 24 to the previous value. Then, the execution of the main routine is restarted through step 3.

At this point, since the difference between the current value and the previous value of the address information is 1 or less, the processor executes step 1, then restarts the main routine immediately after step 3, or further executes steps 2 and 4. After execution, the execution of the main routine is restarted through step 3. As a result, the play operation continues, and the beam spot follows the recording track and gradually moves in the outer peripheral direction.

Here, there is a scratch at a point, and when the beam spot reaches this point, the tracking servo loop is disturbed due to scratches on the disk, etc., causing track jumps, and the beam spot is mistaken at the point located in the inner circumferential direction. And moved. At this point the address information is read,
When the current value and the previous value of the address information are compared, the difference is greater than 1 in terms of points, so the processor
After steps 1 and 2, the process proceeds to step 5, and it is determined whether the first track jump is the second track jump by determining whether or not the jump flag (see step 7) described later is set.

If it is determined in step 5 that the jump flag has not been set, that is, it is the first track jump, the processor sets the previous value of the address information stored in address A ₁ of RAM 24 to A ₂ of RAM 24. The address value is written to the address as the address value immediately before jumping (step 6), and at the same time, the jumping flag indicating that a track jump has occurred is set (step 7). Then, the current value of the address information read at the point is stored in A of RAM 24. Immediately after jumping to address ₃ , the address value is written (step 8). The processor then goes to RAM 24 A ₁
The previous value of the address information stored in the address is the A in RAM24.
₄ write as a search address value at address (step 9), followed by returning to the main routine after executing the subroutine R1 for searching an address indicated by the search address value stored in the RAM24 of A ₄ address. The subroutine R1 is formed based on the address search method disclosed in Japanese Patent Application No. 60-28776.

A so-called search operation is performed by the execution of the subroutine R1, whereby the beam spot reaches a point.
After that, it is assumed that the beam spot reaches a point by the play operation, and the beam spot again causes a track jump due to a scratch or the like at this point. At this time, it is assumed that the beam spot moves to the position of a point and the address information is read at this point. Then, at this point, the difference between the current value and the previous value of the address information becomes larger than 1, so that the processor goes through steps 1 and 2 again to step 5. Since this is the second track jump, it is determined in step 5 that the jump flag is set, and the process proceeds to step 10.

In step 10, the previous value of the address information was
It is determined whether or not the address value immediately before the jump stored in the address A _{2 of the} RAM 24 matches, that is, whether or not two track jumps occur at the same position. Since both the first track jump and the second track jump have occurred at the points, the processor determines that the previous value of the address information and the address value immediately before the jump match, and proceeds to step 11.
If it is determined that the previous value of the address information and the address value immediately before jumping do not match, that is, if the first and second track jumps occur at different positions, the process proceeds to step 6.

In step 11, the processor determines whether or not the current value of the address information is larger than the previous value, that is, whether or not the track jumps to the outer peripheral side. When it is determined to be large, the process proceeds to step 4 and the RAM 24 After writing the current value of the address information to the address A ₁ as the previous value, the execution of the main routine is restarted through step 3. However, at this point, the current value of the address information is smaller than the previous value, so the step
Move to 12 and the current value of address information is RAM2 in step 8.
It is determined whether or not the address value immediately after the jump stored in the address A _{3 of} 4 substantially matches, that is, whether or not the jump destination positions of the first and second jumps are close to each other. The processor goes to step 12
When it is determined that they substantially coincide with each other, a track jump occurs at the same point for the same reason, and the loop flag is set because it is in a loop in which the track jump of the beam spot is repeated between the same positions (−) (step 13), If it is determined that the first and second jump destination positions are far apart, it is determined that a track jump has occurred for a different reason, and a loop flag, a jump flag, an address value immediately before the jump, and an address immediately after the jump. Clear the value (step 1
4) Then, the execution of the main routine is resumed immediately thereafter.

After setting the loop flag in step 13, the processor jumps to step 15 and deducts the predetermined value Ta from the immediately preceding address value, and writes the value as the play interruption address value in the address A ₅ of the RAM 24 to set the point. Designate as the play suspension position. Next, it is judged whether or not the current value of the address information and the play interruption address value match (step 16). If they do not match, the beam spot has not yet reached the point. Returning to the main routine, the beam spot moves by the play operation. When it is determined in step 16 that the beam spot has reached the point, the processor clears the loop plug (step 17), adds the predetermined value Tb to the jumping address value immediately before, and uses that value as the search address value in the RAM 24.
Write to address A ₄ (step 18), and then proceed to subroutine R1 for executing the search operation. As a result, the beam spot jumps over the point by the search operation, moves to a point located on the outer peripheral side of the point, and shifts to the normal play operation.

If it is determined in step 1 and 2 that the track is not skipped, it means that the normal play operation is in progress. However, even in the same play operation, the information detection point may be between the points in FIG. In some cases, the processor can determine whether or not the information detection point is between the points by determining whether or not the loop flag is set in step 3, and the information detection point can be determined between the points. If it is determined that there is, the process proceeds to step 16.

In the above embodiment, the movement of the beam spot from point to point is performed by the search operation by the subroutine R1, but as shown in FIG. 5, it is performed by the so-called long FWD (forward) jump operation by the subroutine R2. However, the same effect as that of the above embodiment can be obtained. A sequence diagram in this case is shown in FIG.
The subroutine R2 is formed based on the track jump method disclosed in Japanese Patent Application No. 60-8885.

Although the method for reading the recorded information on the digital audio disc has been described above, the present invention can be applied to the recorded information reading method on any other information recording disc on which address information is recorded.

As described above, according to the recording information reading method of the present invention, when a track jump occurs, the beam spot is moved from the jump destination position to the address position just before the jump by the track jump operation, and then again. When a track jump occurs at the same position and the jump destination is almost the same position,
The beam spot is moved by the play operation to a position ahead of the position corresponding to the immediately preceding address value by a predetermined distance, and then the beam spot is moved by the track jump operation by a predetermined distance from the position corresponding to the immediately preceding address value. However, by moving to the normal playback operation, the beam spot accidentally moves in the opposite direction to the reading direction due to track jumps due to scratches or dirt on the disc, and the same information is repeatedly read. Even when entering such a loop, the beam spot can be smoothly removed from this loop, so that the recording information can be read well.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an optical disc reproducing apparatus to which the recorded information reading method according to the present invention is applied, and FIG.
FIG. 3 is a diagram showing the relationship between a recording track and a tracking error signal, FIG. 3 is a flow chart showing an operation procedure of an example of a recording information reading method according to the present invention executed by a processor, and FIG. 4 is a flow chart shown in FIG. FIG. 5 is a sequence diagram showing a reading operation, FIG. 5 is a flowchart showing an operation procedure of another example of the recorded information reading method according to the present invention executed by a processor, and FIG. 6 is a sequence diagram showing the reading operation according to the flow of FIG. Is. Description of main part code 1 …… Pickup 6 …… Information recording disk 11 …… Data extraction circuit 12 …… Controller

Claims (1)

[Claims] 1. A reading method for reading information recorded together with address information on the disc while moving an information detection point of a pickup relative to a recording track of the information recording disc in an extension direction thereof. When the difference between the current value and the previous value of the address information sequentially obtained with the relative movement of the information detection point in the expansion direction becomes a predetermined value or more, the previous value is skipped and the current value is set as the immediately preceding address value. Is stored as the address value immediately after the jump, and the information detection point is moved to the position corresponding to the address value immediately before the jump in the disk radial direction by the track jump operation, and then relatively moved in the extension direction. When the difference between the current value and the previous value of the address information sequentially obtained due to this relative movement again exceeds the predetermined value, the address immediately before the jump And the previous value and the address value immediately after the jump and the current value are compared, and when the address value immediately before the jump and the previous value match and the address value immediately after the jump and the current value substantially match, the information The detection point is moved to a position ahead of the position corresponding to the address value just before the jump by a predetermined distance by the relative movement in the extending direction, and then the information detection point is immediately before the jump by the track jump operation. A recorded information reading method for an information recording disk, which is characterized in that it is moved to a position behind a position corresponding to the address value by a predetermined distance, and then a normal reproduction operation is performed.