JPH0330942B2 - - Google Patents

Description

[Detailed description of the invention] Technical field The present invention relates to a recorded information reproducing device.

BACKGROUND ART Conventionally, there has been a device of this type as shown in FIG. In FIG. 1, a high frequency read information signal (hereinafter referred to as RF signal) read from a recording disk (not shown) is transmitted to a demodulation circuit 1, a sync detection circuit 2 and a PLL (phase locked loop).
Supplied to circuit 3. First, the RF signal is converted into interleaved data by the demodulation circuit 1, and
After data errors are corrected by the error correction circuit 4,
The D/A converter 5 converts it into an audio signal. The sync detection circuit 2 detects that a predetermined number of consecutive frame synchronization signals included in the RF signal have not been read, generates a detection output, and then detects that a predetermined number of correct frame synchronization signals are consecutively read again. The sensor is configured to stop generating a detection output when the detection output is detected. The PLL circuit 3 extracts the clock component of the RF signal and synchronizes it with the clock from the master clock generation circuit 7 for correctly rotating the spindle motor 6. The spindle servo circuit 8 controls the spindle motor 6 that holds and rotates the disk based on the control voltage of a VCO (voltage controlled oscillator) included in the PLL circuit 3.

The phase lock state is forcibly removed by a control signal from the outside of the PLL circuit 3, and the
It is configured so that the VCO control voltage can be swept within a predetermined range. Further, the spindle servo circuit 8 is configured to apply a voltage to the spindle motor 6 in response to an external control signal to the extent that the motor 6 can maintain its rotational speed.

Next, the operation will be explained.

When disturbances such as vibrations are applied from the outside and the information reading point goes off track, the data in the RF signal becomes discontinuous and the RF signal is disturbed, making it impossible to correctly reproduce the frame synchronization signal. If the frame synchronization signal is not reproduced a predetermined number of times in succession, the sync detection circuit 2 detects this and uses its detection output to forcibly remove the phase lock state of the PLL circuit 3. Sweep the VCO control voltage within a predetermined range. At this time, the spindle servo circuit 8 supplies the spindle motor 6 with a voltage sufficient to maintain its rotational speed based on the detection output of the sync detection circuit 2. As a result, the spindle motor 6 maintains the rotation speed, and the PLL again
This operation continues until the circuit 3 is phase locked and a predetermined number of correct frame synchronization signals are successively reproduced. Next, when the frame synchronization signal is continuously reproduced a predetermined number of times, the detection output of the sync detection circuit 2 disappears, and the spindle servo circuit 7 again controls the spindle motor 6 based on the control voltage of the VCO in the PLL circuit 3. .

In this way, conventional recorded information reproducing devices are configured to detect the loss of a frame synchronization signal and redo the retraction of the spindle servo based on this detection output, but this was originally due to an error in the PLL circuit. This was done to prevent the frequency from locking, so the control of the spindle motor could be stopped, but no consideration was given to the tracking servo or carriage servo.
However, if the information reading point of the pickup goes out of track, the tracking servo will come off, so if you leave it as it is, the tracking actuator and carriage motor will run out of control, and the correct frame will not be correct no matter how long it takes. The synchronization signal will not be regenerated and the original state will not be able to be restored.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and the present invention prevents runaway of the spindle motor, carriage motor, and tracking actuator even if the information reading point goes out of track due to disturbance such as vibration. It is an object of the present invention to provide a recorded information reproducing device that can prevent such problems.

The recorded information reproducing apparatus according to the present invention detects the omission of a frame synchronization signal included in the read information, detects the off-track of the information reading point based on the tracking error signal, and adjusts the tracking servo based on these detection outputs. The system is configured to control to stop the operation of at least one of the spindle servo system and the spindle servo system.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention. In the figure, parts equivalent to those in FIG. In FIG. 2, a pick-up (not shown)
A tracking error signal indicating a relative positional deviation between the information reading point on the recording disk and the track of the disk in the disk radial direction (direction substantially orthogonal to the track) is sent to the off-track detection circuit 9 and the loop switch 10. Supplied. The off-track detection circuit 9 constitutes first detection means for detecting that the information reading point has crossed a predetermined number of tracks on the disk based on the tracking error signal when the information reading point has gone off track. are doing. On the other hand, the aforementioned sync detection circuit 2 constitutes second detection means. A determination circuit 11 which receives the outputs of the sync detection circuit 2 and the off-track detection circuit 9 determines based on these inputs whether the information reading point has gone out of track or whether the PLL circuit 3 has erroneously locked. According to the determination result, a control signal is sent to the loop switch 10 to open the switch 10 in order to stop supplying the tracking error signal to the tracking servo circuit 12 and the carriage servo circuit 13, and a control signal is sent to the PLL circuit. 3, a control signal for releasing the phase lock is supplied to the spindle servo circuit 8, and a control signal for maintaining the rotational speed is supplied to the spindle servo circuit 8.

The tracking servo circuit 12 controls the position of the information reading point in the disk radial direction by driving the tracking actuator 14 based on the tracking error signal supplied via the loop switch 10. Further, the carriage servo circuit 13 controls the movement of a carriage (not shown) equipped with a pickup in the disk radial direction by driving the carriage motor 15 based on a tracking error signal supplied via the loop switch 10. Eggplant. That is, the tracking servo circuit 12 and the carriage servo circuit 13 constitute a first servo circuit that controls the relative position of the information reading point and the track in the disk radial direction. On the other hand, the spindle servo circuit 8 constitutes a second servo circuit. Reference numeral 16 denotes an address memory for reading the latest address information of the track followed by the information reading point from the data demodulated by the demodulation circuit 1 and storing it.

An example of a specific configuration of the off-track detection circuit 9 is shown in FIG. 3, and the off-track detection circuit 9 includes a detection diode D, a hold capacitor C for peak hold, and a charge capacitor C. A charging resistor R ₁ for determining the time constant of the operation, a discharging resistor R ₂ for discharging the stored charge in the hold capacitor C, dividing resistors R ₃ and R ₄ for setting the reference voltage Vref, and this reference voltage.
This is a peak hold circuit composed of a comparator 16 consisting of an operational amplifier OP which has Vref as an inverting input and the output voltage of the hold capacitor C as a non-inverting input.

Next, the operation of the recording/reproducing apparatus according to the present invention will be explained with reference to the waveform diagram of FIG. 4. In addition,
The basic operation of the spindle servo system is the same as that of the prior art, so a description thereof will be omitted here.

When disturbances such as vibrations and shocks are applied to the apparatus of the present invention and the information reading point of the pickup goes out of track, the tracking error signal becomes a waveform with a large amplitude as shown in FIG. 4a. This tracking error signal is detected by a diode D in FIG. 3 and charges a hold capacitor C with a time constant determined by resistors R ₁ , R ₂ and capacitor C. When the tracking error signal passes the positive peak, the stored charge in the capacitor C is now discharged via the resistor _R2 , and this operation is repeated several times. As a result, the voltage across capacitor C is
The waveform becomes as shown in Figure b. When the voltage b at both ends exceeds the reference voltage Vref determined by the dividing resistors R ₃ and R ₄ , the output of the comparator 16 is inverted as shown in FIG. 4c. In this way, it is detected that several large-amplitude waveforms have occurred in succession in the tracking error signal, that is, that the information reading point has crossed a predetermined number of tracks on the recording disk,
As a result, it is detected that the track has fallen off.

In this manner, when a track-off occurs, the track-off detection circuit 9 operates and sends its detection output to the determination circuit 11. Based on the detection outputs of the sync detection circuit 2 and the off-track detection circuit 9, the determination circuit 11 determines whether the PLL circuit 3 is erroneously locked or not if only the sync detection circuit 2 is generating a detection output.
If only the track-off detection circuit 9 is generating a detection output, the track-off may be a slight one that does not result in a runaway, and if both the sync detection circuit 2 and the track-off detection circuit 9 are generating detection outputs, It is determined that the vehicle is seriously out of track and may run out of control. If the PLL circuit 3 is erroneously locked, the determination circuit 11 sends a control signal instructing the PLL circuit 3 to release the phase lock and the spindle servo circuit 8 to maintain the rotational speed. As a result, the PLL circuit 3 locks the phase again and continues this operation until a predetermined number of correct frame synchronization signals are successively detected.

If it is determined that the vehicle is slightly out of track, the determination circuit 11 does not issue any commands because there is little possibility of runaway, and if it is determined that the vehicle is severely out of track, it opens the loop switch 10. The tracking servo circuit 12 and carriage servo circuit 1
3 operation stops. At this time, address memory 1
6 stores address information read immediately before the vehicle goes off track. By stopping the operations of the tracking servo circuit 12 and the carriage servo circuit 13, the carriage motor 15 stops at the point where the tracking occurs, and the tracking actuator 14 stops at the neutral position (the center of the movable range of the actuator 14). do. After this, the determination circuit 11 issues a command to close the loop switch 10 again, and thereby the tracking servo circuit 12 operates to make the information reading point follow the track closest to that point.
The carriage servo circuit 13 also starts operating again. Then, from the address memory 16, the tracking servo circuit 12 and the carriage servo circuit 1
3, since the information of the stored address is sent out, the tracking servo circuit 12 and the carriage servo circuit 13 control the information reading point to move to the corresponding address.

In the embodiment described above, the off-track detection circuit 9 has a peak hold circuit configuration, so that it can be used even against a single disturbance in the tracking error signal caused by a defect on the disk such as a scratch or a fingerprint. This will allow you to determine whether or not the situation is at the level of a rampage, allowing you to respond appropriately.

In the above embodiment, an address memory 16 is provided, which reads address information and
It may also be a microcomputer that controls various search operations. Furthermore, although the information reading point is moved to the address immediately before the track-off occurs by the output of the address memory 16, even if this address memory 16 and the movement operation based on its output are omitted, runaway can be prevented and This has the effect of shortening the return time. Furthermore, in the above embodiment, no new operation is performed in the case of slight off-track, but the servo bands of the tracking servo circuit and the focus servo (control in the vertical direction of the information reading point with respect to the disk) circuit are changed. By configuring it to widen, once off-track detection is detected, the servo band can be widened and the disturbance rejection capability can be enhanced.

Effects As described above, according to the present invention, the omission of the frame synchronization signal included in the read information is detected, and the off-tracking of the information reading point is detected based on the tracking error signal, and based on these detection outputs. Since the structure is configured to control the operation of at least one of the tracking servo system and the spindle servo system, it is possible to accurately determine whether the PLL circuit is erroneously locked or out of track. A recorded information reproducing device that can prevent the yuator from running out of control is obtained.

The present invention can be applied to any recorded information reproducing apparatus, such as an optical type or an electrostatic type, and these apparatuses include digital audio disc players, video disc players, and the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional recorded information reproducing device, FIG. 2 is a block diagram showing an embodiment of the recorded information reproducing device according to the present invention, and FIG. 3 is a specific example of the off-track detection circuit in FIG. A circuit diagram showing an example of the configuration, and FIG. 4 is a waveform diagram of each part in FIG. 3. Explanation of symbols of main parts, 2...Sink detection circuit, 3...PLL circuit, 6...Spindle motor,
8... Spindle servo circuit, 9... Track disconnection detection circuit, 10... Loop switch, 11...
Judgment circuit, 12...Tracking servo circuit, 1
3... Carriage servo circuit, 14... Tracking actuator, 15... Carriage motor.

Claims (1)

[Scope of Claims] 1. The relative position of the information read point on the recording disk by pick-up and the track of the recording disk based on a tracking error signal indicating a relative positional deviation in a direction substantially perpendicular to the track. and a second servo circuit that controls the rotational speed of the recording disk based on a frame synchronization signal included in information read from the pickup. a first detection means for detecting that the information reading point has crossed a first predetermined number of tracks on the recording disk based on the tracking error signal and generating a first detection signal; a second detection means for detecting that the frame synchronization signal has not been read a second predetermined number of times in succession and generating a second detection signal;
A recorded information reproducing apparatus comprising: control means for controlling the operation of at least one of the first and second servo circuits to be stopped based on the detection signal. 2. The control means has a storage means for storing address information immediately before the information reading point crosses the track, and after stopping the operation of the first servo circuit, the control means returns to the address stored in the storage means. 2. The recorded information reproducing apparatus according to claim 1, wherein said information reading point is controlled to be moved. 3. The control means stops the operation of the second servo circuit when only the second detection signal is generated, and stops the operation of the second servo circuit when both the first and second detection signals are generated. The recorded information reproducing apparatus according to claim 1, characterized in that the operation of the servo circuit is stopped. 4. The recorded information reproducing apparatus according to claim 3, wherein the control means performs control to widen the servo band of the first servo circuit when only the first detection signal is generated. .