JPS6362809B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for tracking a rotating recording medium, a recording medium used in this tracking method, and an information reproducing apparatus.

An example of a conventional method is shown in FIG. In FIG. 1, track 1 indicates a portion of a recording track recorded in a spiral shape on the surface of a disc-shaped recording medium. The disk is rotated at a constant rotational speed, for example 1800 rpm. Signal reproduction is performed by shining an optical spot 2 on this track. Sufficient S/N so that changes in the amount of light reflected or transmitted on the surface of the recording medium depending on the recorded signal (recorded in the form of shading or unevenness) are converted into electrical signals by the photodetector.
In order to reproduce the signal, the optical spot 2 must trace the center of the signal recording track 1. An auxiliary light spot 34 is used for this purpose. The light spot 3 is offset from the light spot 2 by a minute distance 5 in the direction perpendicular to the track. In addition, light spot 4 is related to light spot 2,
It is shifted by the same distance 5 in the opposite direction to the light spot 3. If the output is the highest when the optical spot is at the center of track 1, and the output decreases no matter which side it deviates from the center, then the signal output corresponding to optical spot 3 and optical spot 4 will be the same. By detecting the difference in the signal outputs corresponding to , it is possible to determine how far the optical spot 2 is deviated from the center of the track. Tracking can be performed using this difference signal. Although this method is very simple, it requires an optical system to create two extra light spots and an extra photodetector to detect these signals.

Another conventional method is shown in FIG. In FIG. 2, reference numeral 1 indicates a signal recording track recorded on the surface of the disk, as in FIG. 6 shows the trajectory drawn by the light spot 2 on the disk when the disk is rotated.
That is, in this example, the optical spot 2 is forcibly vibrated in the direction perpendicular to the track. Then, the waveform of the optical output changes depending on the amount of deviation of the center of vibration of the optical spot from the center of the track and the direction of the deviation. Tracking is performed by detecting the amount and direction of deviation based on changes in this output waveform. In this case, it is necessary to move the light spot at a frequency that is considerably higher than the frequency of the truck vibration.
An optical system is required for this purpose.

The present invention relates to a tracking method that does not require an extra optical system as described above in a reproduction system.

The tracking method of the present invention has tracks extending in the rotational direction, and detects tracking detection signals provided alternately in opposite directions and shifted by a predetermined distance from the center line of the tracks. The above timing signal is recorded using a recording medium intermittently recorded along the track so that the timing signal of The tracking detection signals provided in opposite directions with respect to the track are taken out, and the track deviation signal indicating the deviation from the center line of the track is detected using the extracted tracking detection signal, and the track deviation is detected. The method is characterized in that the above-mentioned track is tracked using a signal.

The recording medium of the present invention has tracks extending in the rotational direction, and tracking detection signals provided alternately in opposite directions and shifted a predetermined distance from the center of the tracks, and tracking detection signals for detecting the tracking detection signals. Timing signal and rotation frequency of 500
It is characterized in that it is recorded intermittently along the track so that it can be obtained more than twice as many times.

Further, the information reproducing apparatus of the present invention records information signals along a track extending in the rotational direction, and records tracking detection signals provided alternately in opposite directions at a predetermined distance from the center line of the track. A recording medium is intermittently recorded along the track so that a timing signal for detecting the tracking detection signal can be obtained repeatedly at 500 times the rotational frequency or more, and the signal reproduced from the recording medium is means for separating and extracting the tracking detection signals provided in opposite directions with respect to the track using the included timing signals; and a means for separating and extracting the tracking detection signals provided in opposite directions with respect to the track, and and means for detecting a track deviation signal indicating a deviation from the center line of the track, and reproducing the information signal along the center line of the track while correcting the deviation using the track deviation signal. It is characterized by

According to the present invention, for example, by recording a tracking signal in the horizontal blanking portion of a television signal, tracking can be performed without affecting the reproduced image quality.

The repetition frequency of the horizontal synchronization signal of the television signal is approximately 15KHz. When recording television signals in a spiral manner, the rotational speed of the disk is usually
It is around 1800rpm. Therefore, the frequency of the main component of track vibration is only about 30 Hz or relatively low-order harmonics thereof. Therefore, if information regarding tracking can be obtained by repeating the signal at approximately 15 KHz, this value is sufficient as a detection signal for tracking. That is, the rotation frequency is approximately 30 Hz, and since tracking detection signals are obtained repeatedly at 15 KHz or more, which is 500 times that frequency, tracking deviation signals can be stably detected.

Furthermore, in the present invention, since the timing signal for detecting the tracking detection signal is intermittently recorded together with the tracking detection signal, it is necessary to provide a recording medium exclusively for the timing signal or to detect the rotation of the recording medium. , there is an advantage that there is no need to provide a special timing signal generation means to detect the tracking detection signal, and since the timing signal and the tracking detection signal are provided on the same recording medium, the tracking detection signal Signals can be extracted more accurately.

The present invention will be described below with reference to Examples. FIG. 3 is a diagram showing an embodiment of the present invention. This figure shows the recording pattern of the signal recording track of the present invention. In the figure, 7 indicates the horizontal blanking portion of the television signal. The first part 8 of the horizontal blanking part is a part representing a horizontal synchronization signal. The following part 23 has a constant frequency _{of 1} , and the part 24 has a constant frequency of _2.
signals are recorded. As shown in the figure, frequency ₁ and frequency ₂ signals are alternately recorded for each horizontal blanking, and the portion 23 where frequency ₁ is recorded is shifted by a fixed distance 9 in one direction compared to the other portions. Further, the portion 24 where ₂ is recorded is shifted by the same distance 9 in the opposite direction from the ₁ recorded portion.
The outputs of signals ₁ and ₂ are output alternately for each horizontal blanking, but if you take the difference in the optical output for _{the 1} signal _{and 2} signals for a fairly long time compared to one horizontal scanning section, this difference signal 10 The relationship between this and the amount of deviation 11 of the light spot is as shown in FIG. Therefore, from the signal 10, it can be determined in which direction and by how much the light spot is deviated from the center of the track. Therefore, this signal can be used as a detection signal for tracking.

Figure 5 shows how to record signals at frequencies ₁ and ₂ . In Fig. 5, 12 and 13 are lenses, and 14
indicates a light source, for example a laser. 15 indicates a recording medium. The light emitted from the light source is modulated by an optical modulator 26 corresponding to a television signal. Signals of frequencies ₁ and ₂ are inserted alternately into the horizontal blanking section of the television signal. An optical deflector 16 is placed between the optical modulator 26 and the lens 12. 1
6, an optical deflector using an acousto-optic effect or an electro-optic effect is suitable. The optical deflector 16 allows the optical spot 2 to be shifted by a minute distance. The deflection signal to the optical deflector 16 is transmitted from a recording television signal generation source 27 to a synchronization separation circuit 2.
8 to the deflection pulse generating circuit 29. In order to shift the light spot as shown in Figure 3, it is necessary to deflect the light in a fairly short time compared to the horizontal blacking period, but if the acousto-optic effect and electro-optic effect are used, the above-mentioned deflection can be achieved. A sufficiently fast deflection is possible to meet the requirements of

In order to generate signals ₁ and ₂ , as shown in FIG. 6, the signal waveform of the horizontal blanking portion 25 is created by forming steps 15 and 16 of different heights as shown in the figure.
, and modulate it to FM. Then step 15,
The signal frequency is converted to a signal frequency corresponding to 16. Also
Take arbitrary recordable frequencies as ₁ and ₂ , and cut off pulse 17 in the first part of the horizontal sync pulse.
By creating a signal and removing signals ₁ and ₂ , only the signal for tracking can be detected without being affected by other signals.

FIG. 7 shows a signal regeneration circuit. Signal detection device 4
The signal detected at 5 is amplified by an amplifier 46 and converted to a television signal by a demodulator 47. The skipping pulse shown in FIG. 6 is generated by the skipping pulse generating circuit 31 from the synchronization pulse generated from the television signal by the synchronization separation circuit 30. This stripping pulse serves to strip only the tracking signal portion of the detection signal by the gate 32. The tracked signals are sent to bandpass filters 33 and 34 having center frequencies ₁ and ₂ , respectively. The signal output from the filter passes through envelope detection circuits 35, 36 and low frequency filters 37, 38, and an arithmetic circuit 39 generates a difference signal between the two. This difference signal is sent to amplifier 4
The signal is amplified by 0 and sent to a device 41 that drives a signal detection means (for example, a light spot).

Next, another embodiment of the present invention is shown in FIG. In this example, the same signal ₁ is recorded in portions 23 and 24. Take the horizontal synchronization signal as a reference signal, and for example, using the vertical synchronization signal as a reference, shift the part that records frequency ₁ in one direction for even-numbered horizontal scanning sections, and shift it in another direction for odd-numbered horizontal scanning sections. and record it. A reference pulse 18 which determines this deflection direction is shown. Also, the light spot is the 8th one.
In FIG. 9, the output signals of frequency ₁ when shifted upward (position 19) and downward (position 20) from the track center are shown as 21 and 22, respectively. For example, if the signals 21 and 22 are multiplied by the reference signal 18, the multiplication output will be positive in the case of the signal 21 and negative in the case of the signal 22. Therefore, by this multiplication, information on how far and in which direction the light spot is shifted can be obtained.

FIG. 10 shows a circuit diagram of the reproducing device in this embodiment. The regeneration circuit is largely the same as that shown in FIG. In this case, there is only one bandpass filter, and the envelope-detected signal is applied to the multiplier 43. From the synchronization pulse produced by the synchronization separation circuit 30, a reference pulse for determining the optical deflection shown in FIG. 8 is produced by the reference pulse generation circuit 42. Further, the reference pulse and the detection tracking signal are multiplied by a multiplier 43, and sent through a low frequency filter 44 to a means 41 for moving the optical spot in a direction perpendicular to the track.

As described above, in the present invention, the tracking detection signals are alternately recorded while being shifted by a predetermined distance from the center line of the tracks in the opposite direction, and the timing signal for detecting the tracking detection signals is also
Since the recording was performed intermittently along the track so as to be obtained over 500 times more times, it was necessary to provide a recording medium exclusively for timing signals or to detect the rotation of the recording medium to extract the tracking detection signal. It is possible to stably detect a track deviation signal with a sufficient S/N ratio without providing a special timing signal generating means.

Embodiments of the invention include optically recording the signal;
Although the example of reproduction has been given, the present invention is not limited to this, and can be applied to all devices in which signals are recorded in the form of recording tracks in time series, such as other methods such as magnetic recording and reproduction methods. Of course it will be done.

[Brief explanation of drawings]

1 and 2 are diagrams showing a conventional tracking signal detection method, FIG. 3 is a diagram showing a recording track of the present invention, FIG. 4 is a diagram showing a tracking signal detected by the present invention, and FIG. 5 is a diagram showing a tracking signal detected by the present invention. 6 is a diagram showing a signal recording method, FIG. 6 is a diagram showing a recording signal pattern, FIG. 8 is a diagram showing another type of recording track of the present invention, and FIG. 9 is a diagram showing the track of FIG. 8. Figure 7 shows the reproduced waveform of the tracking signal when
FIG. 10 is a block diagram showing a tracking signal reproducing circuit according to the present invention.

Claims (1)

[Scope of Claims] 1. It has a track extending in the rotational direction and on which an information signal is recorded, and during a synchronization period for reproducing the information signal, the tracks are alternately moved from the center line of the track in opposite directions. A tracking detection signal provided at a predetermined distance in a direction perpendicular to the formation direction and a timing signal for detecting the tracking detection signal are intermittently provided along the track so that the tracking detection signal and the timing signal for detecting the tracking detection signal can be obtained repeatedly at 500 times the rotation frequency or more. the tracking detection signals provided in opposite directions to the track using the timing signal included in the signal reproduced from the recording medium; A tracking method comprising: detecting a track deviation signal indicating a deviation of the track with respect to a center line using a tracking detection signal obtained by tracking the track; and tracking the track using the track deviation signal. 2. It has a track extending in the rotational direction and on which an information signal is recorded, and during a synchronization period for reproducing the information signal, the track is alternately moved in opposite directions from the center line of the track in a direction perpendicular to the direction in which the track is formed. A tracking detection signal provided at a predetermined distance and a timing signal for detecting the tracking detection signal are intermittently recorded along the track so as to be obtained repeatedly at 500 times the rotational frequency or more. A recording medium characterized by: 3. Record information signals along a track extending in the rotational direction, and during a synchronization period for reproducing the information signal, record information signals in alternating directions from the center line of the track in a direction perpendicular to the direction in which the track is formed. A recording medium in which a tracking detection signal provided at a predetermined distance and a timing signal for detecting the tracking detection signal are recorded intermittently along the track so that the tracking detection signal is repeatedly obtained at 500 times the rotational frequency or more. means for separating and extracting the tracking detection signals provided in mutually opposite directions with respect to the track using the timing signal included in the signal reproduced from the recording medium; means for detecting a track deviation signal indicating the deviation of the track with respect to the center line based on the difference between the extracted tracking detection signals; An information reproducing device characterized in that the information signal is reproduced along a center line.