JP3440841B2 - Optical disc playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc reproducing apparatus capable of reproducing information recorded on an optical disc recording medium.

[0002]

2. Description of the Related Art A conventional optical disk reproducing apparatus is disclosed in Japanese Patent Laid-Open No. 8-
No. 87753 is known, and is provided with means for detecting the temperature around the optical pick, and means for re-adjusting the tracking balance when it is detected that the change exceeds a predetermined range. Has been done.

[0003]

In such an optical disk reproducing apparatus, a special detecting circuit and control circuit are required as temperature measuring means. Further, there is a problem that an effect cannot be obtained with respect to a factor that causes a tracking balance deviation that does not accompany a temperature change, such as a tracking balance deviation that occurs when the posture of use is changed such as in a portable reproducing device. The present invention uses a circuit that can be realized relatively easily, does not limit the factors that cause the tracking balance deviation, detects the tracking balance deviation in a short time, and performs tracking balance readjustment to reproduce the tracking balance deviation. The present invention has been made for the purpose of providing an optical disk reproducing device capable of quickly returning from a difficult state.

[0004]

[Means for Solving the Problem] In solving the problem, as a result of examining the tracking balance deviation,
In order to read the information signal recorded on a specific track of the optical disc-shaped recording medium by an optical pick, in an optical disc reproducing device that performs various servo operations such as focus servo, tracking servo, and sled servo, the tracking balance may be lost. When performing servo pull-in, the tracking coil is driven to follow the position deviated from the center of the track, which affects the tracking error signal waveform, and the state where the tracking coil is further driven is repeated, As a result, it was confirmed that the tracking coil was largely driven to one side in a short time, which caused the signal level of the DC component of the tracking error signal to rise in a short time.

The optical disk reproducing apparatus of the present invention samples the signal of the DC component of the tracking error signal detected by the optical pick at a constant time interval based on the above-mentioned confirmation items so that the signal level does not exceed a predetermined level. By monitoring and detecting that a predetermined level has been exceeded,
The state where the tracking balance is deviated can be automatically detected, and the tracking balance can be quickly readjusted.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, an information signal recorded on a specific track of an optical disk recording medium is read by an optical pick. Therefore, a focus servo, a tracking servo, and a thread servo are performed. In an optical disk reproducing apparatus that performs various servo operations such as sampling means for sampling the DC component of the tracking error signal detected by an optical pick at fixed time intervals, and the DC component of the sampled tracking error signal has a predetermined signal level. do not exceed the plant
It is provided with a monitoring means for monitoring at regular time intervals and a means for re-adjusting the tracking balance when the signal level exceeds a predetermined level by the monitoring means, and the tracking balance is deviated and the reproduction becomes difficult. At times, the state can be automatically detected, and the tracking balance can be quickly readjusted.

According to a second aspect of the present invention, the sampling by the sampling means is performed at the same timing as the sampling of the DC component of the tracking error signal in the sled servo at a constant time interval, which is relatively easy. With such a circuit configuration, it is possible to detect a state where the tracking balance is deviated by the control processing.

According to a third aspect of the present invention, there is provided means for detecting the signal level of the DC component of the tracking error signal only for a certain period of time after the tracking pull-in.
With respect to the level change of the DC component of the tracking error signal other than the deviation of the tracking balance, the risk of erroneous detection can be avoided, and the processing complexity can be eliminated.

[0009]

According to a fourth aspect of the present invention, while the information signal recorded on the optical disk recording medium is being read by the optical pickup while performing various servo operations, the read data has many errors and is difficult to reproduce. In this state, the tracking servo is once turned off, the means for performing the tracking pull-in again is used, and the means for detecting the signal level of the DC component of the tracking error signal is provided. When the information signal recorded on the disc-shaped recording medium becomes difficult to read, the tracking balance deviation can be detected immediately.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5. (Embodiment 1) FIG. 1 shows a system block diagram of an optical disk reproducing apparatus according to a first embodiment of the present invention.
In FIG. 1, 1 is a disk-shaped recording medium, 2 is an optical pick, 3 is an RF amplifier, 4 is a system controller for controlling the entire system, and 5 is a servo control circuit. Reference numeral 6 is a driver for driving an optical pick, a thread motor, or a spindle motor, and a focus drive signal F
The OD, the tracking drive signal TRD, the sled drive signal SLD, and the spindle drive signal SPD are output. Reference numeral 7 is a sled motor, 8 is a spindle motor, and 9 is a digital signal processing circuit. Further, the system controller 4 constitutes a sampling means 4a, a monitoring means 4b, and a tracking balance readjustment means 4c. In addition,
Descriptions of blocks after the digital signal processing 9 will be omitted.

The operation of the optical disc reproducing apparatus configured as described above will be described below. The information signal recorded on a specific track of the disc-shaped recording medium 1 is read by the optical pick 2. As a servo mechanism, the optical pick 2 includes a tracking coil for making the objective lens follow the tracking direction, a focus coil for adjusting the distance between the objective lens and the disk-shaped recording medium, and the like. The tracking coil and the focus coil are driven by drive signals TRD and FOD output from the driver 6, respectively. The entire optical pick 2 can be moved by the sled motor 7, and is driven by the drive signal SLD output from the driver 6. Further, a spindle motor 8 is provided for rotating the disc-shaped recording medium, and is driven by a drive signal SPD output from the driver 6.

The information signal read from the optical pick 2 is R
Of the signals amplified by the F amplifier, the servo error signal is sent to the servo control circuit 5, and the information signal is sent to the digital signal processing circuit 9 to restore the information. The signal sent to the digital signal processing circuit 9 is controlled by the system control 4 and sent to the subsequent signal data output block. On the other hand, regarding the servo error signal, a control signal is sent to the driver 6 to correct various servo errors by the servo control circuit 5, and the driver 6 drives each servo mechanism to perform servo control. The servo control circuit 5
From the system controller 4, a DC component signal of the tracking error signal is sent from the system controller 4 via the servo control circuit 5 to a sled movement process,
Tracking balance adjustment etc. can be performed.

Next, the signal of the DC component of the tracking error signal will be described with reference to the block diagram of FIG. Figure 2
, 3 is an RF amplifier, 5 is a servo control circuit, 51
Is an A / D converter, 52 is a tracking servo equalizer filter, and 53 is a low-pass filter. A / D
The converter 51, the tracking servo equalizer filter 52, and the low-pass filter 53 are part of the circuit built in the servo control circuit 5. Signals in the above configuration will be described. Since the tracking error signal (TE) of the servo error signal output from the RF amplifier 3 is processed by the digital filter, the A / D converter 51 converts the analog signal into a digital signal, and then the tracking servo equalizer filter 52. To generate a tracking error signal with servo characteristics.
On the other hand, the DC component of the tracking error signal is extracted from the tracking error signal through the low-pass filter 53.
Generating the component signal.

Next, the processing of the system control 4 in FIG. 1 will be described with reference to the flowchart in FIG. The signal of the DC component of the tracking error signal input from the servo control circuit 5 to the system controller 4 is sampled at 10 ms intervals. The voltage of the DC component signal of the tracking error signal input in S1 is measured, and the voltage measured in S2 is added to the total voltage. However, since the signal of the DC component of the tracking error signal has a polarity, it is taken into consideration. In S3, it is determined whether the sampling is performed 20 times in total. If the sampling is still less than 20 times, the sampling counter is incremented by 1 in S5, and the process ends. On the other hand, when the sampling is completed 20 times, the average value is calculated from the total voltage in S4. That is, the average value of the voltage of the DC component signal of the tracking error signal input in 200 ms is obtained. After that, in order to perform initialization for the next sampling, the sampling counter is cleared in S6 and the voltage total is cleared in S7. In S8, it is determined whether or not the average value calculated in S4 exceeds a predetermined saturation voltage. If not, the process ends as it is. On the other hand, if it exceeds, it is determined that the tracking balance is deviated, a request for readjustment of the tracking balance is set in S9, and the process is exited. After that, it is detected that a request for readjustment of the tracking balance is made in another process, and readjustment is performed. The value of the saturation voltage is sufficiently larger than the maximum value of the range in which the signal of the DC component of the tracking error signal changes in the normal reproduction state, and the speed of tracking balance detection and the degree of erroneous detection are determined. It is arbitrarily set in consideration. Further, the sampling interval of the DC component of the tracking error signal of 10 ms is a value arbitrarily set so that an appropriate average value can be obtained in 200 ms, and the interval of 200 ms for obtaining the average value is equal to that of the disc-shaped recording medium. It is a value arbitrarily set according to the rotation cycle of the spindle so as to reduce the influence of eccentricity.
In this embodiment, the rotation cycle near the outermost circumference of the disc is about 1
Since it is 00 ms, it is set to a doubled value of 200 ms with a margin.

As described above, according to this embodiment, it is possible to automatically detect the deviation of the tracking balance. (Second Embodiment) Next, FIG. 4 shows a system block diagram of an optical disk recording / reproducing apparatus according to a second embodiment.
The system indicated by is an MD which is one of the optical disk reproducing devices.
It is a recording and playback system. In FIG. 4, 101 is M
D, 102 are optical picks, 103 is an RF amplifier, 104 is a microcomputer which is a system controller, 105 is a servo control circuit, 106 is a focus drive signal FOD and a tracking drive signal TRD for driving an optical pick, a thread motor or a spindle motor, A driver that outputs a sled drive signal SLD and a spindle drive signal SPD, 107 is a sled motor, 108 is a spindle motor, and 109 is digital signal processing (EF).
M, ACIRC decoder / encoder), 110 is AD
IP decoder, 111 magnetic head drive, 112 magnetic head, 113 memory controller, 114 DR
AM, 115 is audio decompression / compression (ATRAC), 116
Is a D / A converter, 117 is an A / D converter, 118 is a microcomputer I / F, 119 is a display, and 120 is a key / SW.

The operation of the MD recording / reproducing apparatus configured as described above will be described below. MD10
The information signal recorded in 1 is read by the optical pick 102, the read signal is amplified by the RF amplifier 103, and is divided into an ADIP signal, a servo error signal, and an information signal. Of the amplified signals, the ADIP signal is input to the ADIP decoder 110, decoded into ADIP address information, synchronized by the digital signal processing 109, and input to the servo control circuit 105. Also,
Of the amplified signals, the servo error signal is input to the servo control circuit 105. In response to the input signal, the servo control circuit 105 drives a tracking coil and a focus coil in the optical pick, a sled motor 107 for moving the entire optical pick, and a spindle motor 108 for rotating the MD101 via a driver 106 to drive various servos. It's working. Finally, the information signal is subjected to EFM demodulation and ACIRC error correction by the digital signal processing 109, and then the storage address is managed by the memory controller 113 and temporarily stored in the DRAM 114. The information signal once stored is subjected to ATRAC by voice compression / decompression 115.
The data is decoded, converted into analog voice by the D / A converter 116, and output as audio. Also, when recording, analog signals are input from the audio input and A / D
After being quantized and sampled by the converter 117, it is ATRAC encoded by the audio compression / decompression 115. afterwards,
Addresses stored in the memory controller 113 are managed D
Once stored in RAM 114, digital signal processing 1
At 09, an ACIRC error correction code is added, and after EFM modulation, the magnetic head drive 111 drives the magnetic head 112 by magnetic field modulation, and the data is recorded on the MD 101.

The servo control circuit 105, digital signal processing 109, and memory controller 113 are controlled by transmitting and receiving commands to and from the system control microcomputer 104 via the microcomputer I / F 118. Can monitor the signal of the DC component of the tracking error signal from the servo control circuit 105, and can also control the movement of the sled and the tracking balance adjustment by transmitting a command. In addition, the system controller 104 uses the key / SW 120 as an input device and the display 11 as an output device.
9 is managed.

Next, the processing of the system control 104 will be described with reference to the flowchart of FIG. The operation in FIG. 5 is obtained by adding the sampling of the DC component of the tracking error signal in the sled servo to the sampling operation of the DC component of the tracking error signal for detecting the tracking balance deviation of the operation of FIG. 3 in the first embodiment. So both samplings are done at the same time. Since both tracking error signals can be configured to read the same signal, they can be relatively easily realized by using a conventional circuit. Similar to the operation of FIG. 2 in the first embodiment, S21 to S27 are performed every 10 ms in S21.
In step S22, the voltage of the DC component of the tracking error signal is measured, the total voltage is calculated, and if it is determined in step S23 that the measurement has not been performed for a total of 200 ms, the sampling counter is incremented by 1 in step S25 and the processing is terminated. On the other hand, when it is determined that the measurement is performed for 200 ms, the next 200 times are cleared by clearing the sampling counter in S26 and clearing the total voltage in S27.
After performing the initialization process of sampling for ms, the determination of S28 is performed. In S28, it is determined whether the average value of the DC component signal of the tracking error signal does not exceed a predetermined voltage to see if it is within a range in which the tracking servo drive can be sufficiently followed without removing the tracking servo. If not, the process is left as it is. on the other hand,
If it exceeds the predetermined voltage, it is checked in S29 whether the average value of the DC component signal of the tracking error signal exceeds the saturation voltage, and if it does not exceed, the request flag for moving the thread by 90 μm in S31. Set and exit the process. Thereby, the sled servo operation is performed. On the other hand, when the voltage exceeds the saturation voltage, it is determined that the tracking balance is deviated, the tracking balance readjustment request flag is set in S30, and the process ends. As a result, the tracking balance deviation can be detected. As a matter of course, the tracking error signal D
The voltage compared in S28 with respect to the average value of the voltage of the C component signal is lower than the voltage compared in S29. The reason why the movement amount in the sled servo is set to 90 μm is as follows. Since the signal of the DC component of the tracking error signal in the sled servo is sampled at the same time as the sampling of the signal of the DC component of the tracking error signal for detecting the tracking balance deviation, the tracking error is generated when the tracking balance deviation occurs. Depending on how the signal of the DC component of the signal rises, the sled movement in the sled servo may be performed before the tracking balance deviation detection.
In that case, if the sled movement amount is large, the signal of the DC component of the tracking error signal changes, and the tracking balance deviation state cannot be detected. Therefore, the movement amount in the sled servo is set within the range in which the lens can move during reproduction. , When the tracking balance is off,
The correction of the sled by one sled servo cannot be completely corrected, and the tracking balance shift can be achieved by maintaining the state in which the signal level of the DC component of the tracking error signal exceeds the saturation voltage at least until the next sampling cycle. Can be normally detected.

By the way, in such an MD recording / reproducing apparatus, at the time of reproduction, ATR is performed by 115 blocks of audio compression / expansion.
Since AC decoding is performed, the data stored in the DRAM 114 is controlled by the memory controller 113 by utilizing the difference in transfer rate between the block output side and the input side.
Since the intermittent reading is performed, the tracking servo is re-pulled in every intermittent reading. Since the tracking balance of the present invention is detected when the tracking servo is pulled in, it is advantageous in a system that performs intermittent reading such as an MD reproducing device.

Further, in the case of a portable MD recording / reproducing apparatus, there is a means for adjusting the tracking balance every time the intermittent reading is started in order to eliminate the deviation of the tracking balance which occurs when the posture is changed, but in that case, the tracking balance is adjusted. Each adjustment requires about several hundred ms of adjustment time, which shortens the battery life. Therefore, there is also an advantage that the power consumption can be reduced by monitoring the DC component of the tracking error signal and readjusting the tracking balance only when the tracking balance deviation is detected.

Further, in an abnormal state such as a state in which there is an error in the read data, by using a means for turning off the tracking servo once and re-pulling in, when an abnormal state is caused by a tracking balance deviation,
Since the tracking balance can be readjusted as soon as it is detected, it is possible to quickly return to the normal state.

As described above, according to the present embodiment, the tracking balance deviation can be automatically detected without a malfunction with a relatively easy system configuration, and the abnormal state can be quickly recovered.

[0024]

As described above, according to the present invention, it is possible to automatically detect a tracking balance deviation state with a relatively easy circuit configuration and control process, and perform tracking balance readjustment promptly. The advantageous effect that it is possible to recover from the state where the reading of the information signal is difficult is obtained.

[Brief description of drawings]

FIG. 1 is a system block diagram of an optical disk reproducing device according to a first embodiment of the present invention.

FIG. 2 is a signal generation block diagram of a DC component of the tracking error signal.

FIG. 3 is an operation flowchart of the system controller.

FIG. 4 is a system block diagram of an MD recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 5 is an operation flowchart of the system controller.

[Explanation of symbols]

1 Disc-shaped recording medium 2 optical picks 4 system controller 4a sampling means 4b Monitoring means 4c Tracking balance readjustment means 5 Servo control circuit 6 drivers 7 thread motor 101 MD 102 optical pick 104 System control microcomputer 105 Servo control circuit 106 driver 107 thread motor FOD focus drive signal TRD tracking drive signal SLD thread drive signal SPD spindle drive signal

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-9-54965 (JP, A) JP-A-4-214236 (JP, A) JP-A-59-77639 (JP, A) JP-A-8- 203107 (JP, A) JP 9-63078 (JP, A) JP 10-283645 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 7/09-7 /Ten

Claims (4)

(57) [Claims] 1. An optical disc reproducing apparatus that performs various servo operations such as focus servo, tracking servo, and sled servo to read an information signal recorded on a specific track of an optical disc-shaped recording medium by the optical pick. Sampling means for sampling the detected DC component of the tracking error signal at fixed time intervals, and monitoring means for monitoring whether or not the sampled DC component of the tracking error signal exceeds a predetermined signal level at predetermined time intervals. An optical disk reproducing apparatus comprising a means for readjusting a tracking balance when the monitoring means exceeds a predetermined signal level. 2. The optical disk reproducing apparatus according to claim 1, wherein the sampling means performs sampling at the same timing as sampling in which the DC component of the tracking error signal is sampled at fixed time intervals in the sled servo. 3. The optical disk reproducing apparatus according to claim 1, further comprising means for detecting the signal level of the DC component of the tracking error signal only for a fixed time after the tracking pull-in. 4. When an optical pickup is reading an information signal recorded on an optical disc-shaped recording medium while performing various servo operations, and when the read data has many errors and is difficult to reproduce, 2. The optical disk reproducing apparatus according to claim 1 , further comprising means for turning off the tracking servo and again performing tracking pull-in, and means for detecting the signal level of the DC component of the tracking error signal.