JPH0554307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a video disk device, and in particular, a disk-shaped recording medium (hereinafter referred to as a disk) on which a video signal having a positive synchronization signal is recorded is processed at a constant linear velocity. The present invention relates to a video disc device equipped with a motor control device suitable for rotational driving.

[Background of the invention]

Research is being carried out on so-called high-definition television systems, which have significantly improved resolution compared to current standard television systems, such as the NTSC system. As the quality increases, the required transmission bandwidth increases, so technology that compresses the video signal bandwidth will be necessary for practical use. Regarding this, MUSE has recently been developed as an effective technology to significantly compress the bandwidth.
(Multiple Sub-Nyquist Sampling Encoding)
A method was proposed.

The content of this MUSE system is described in "Satellite one-channel transmission system for high-definition television (MUSE)" by Ninomiya, Otsuka, and Izumi in the Technical Report of the Television Society, VOL.7, No.44 (March 1984). It has been announced. According to this technology, as shown in Fig. 2, two chromaticity signals C ₁ and C ₂ are time-division multiplexed with a luminance signal Y in a line-sequential manner alternately every horizontal scanning period, and a horizontal synchronization signal HD ₁ , HD ₂ and frame pulse FP are
It is multiplexed at a level that does not exceed the maximum amplitude of the luminance signal or chromaticity signal, so-called positive polarity. If such a positive polarity synchronization method is used, so-called synchronization loss is eliminated, so there is an advantage that the S/N ratio of the transmitted video signal increases.

Regarding the reliability of separating and detecting the positive polarity synchronization signal multiplexed with this video signal, the above technical report states that experiments have shown that the phase lock of the receiver is working as expected, which poses a practical problem. It is stated that there is no. In this way, when the frequency of the input video signal hardly changes, such as when receiving a video signal sent from a broadcasting station, malfunctions are less likely to occur. However, as shown in FIG. 2, for example, using the feature that the frame pulses FP of line No. 605 and line No. 606 have opposite polarities,
Since this frame pulse is identified, if the frequency of the video signal fluctuates significantly, there is a risk that this identification will malfunction.

This is particularly a problem when reproducing a disc on which video signals are recorded at a constant linear velocity. Even if the linear velocity fluctuates significantly during startup or access,
If the video signal is in a negative polarity synchronization format such as the NTSC system, the synchronization signal can be easily and accurately detected by amplitude separation, so this playback synchronization signal is used to control the disc motor so that the linear velocity is constant. can be controlled. In contrast, the above MUSE
In the case of a video signal in a positive polarity synchronization format such as the above method, when the linear velocity changes significantly at startup or access, there is a risk that the positive polarity synchronization signal separation detection function may malfunction. Furthermore, if an attempt is made to prevent this malfunction, the circuit for identification becomes complicated.

[Purpose of the invention]

In view of the above points, an object of the present invention is to control the rotation of a video disk on which a video signal and an audio signal are recorded at a constant linear velocity even if the video signal has a synchronization signal of positive polarity. An object of the present invention is to provide a video disc device capable of stably and reliably reproducing video signals and audio signals.

[Summary of the invention]

To achieve the above object, the present invention provides a video disc in which a video signal in a high frequency band, an audio signal in a low frequency band, and a pilot signal having a frequency band between these two signals are superimposed, and a certain line is produced. During playback, the pilot signal is used to control the video disc to rotate at a constant linear velocity.

[Embodiments of the invention]

Hereinafter, the present invention will be explained using the drawings.

FIG. 1 is a block diagram of an optical video disc device showing one embodiment of the present invention. In FIG. 1, on disk 1 _, a luminance signal Y and two chromaticity signals C ₁ and C ₂ as shown in FIG.
A video signal having HD ₂ and a digital audio signal which is time-base compressed and multiplexed within the vertical blanking period of this video signal are both FM modulated and recorded, and this FM modulated video signal and A pilot signal having a predetermined frequency lower than that of the audio signal is frequency multiplexed and recorded along a spiral track at a constant linear velocity.
When this constant linear velocity method is used, the recording density is the same on the inner and outer circumferences of the disk, and a longer recording time can be obtained than with the constant rotation speed method.

During playback, a light beam is irradiated from the pick-up mechanism 3 onto the information on the disk 1 that is rotationally driven by the disk motor 2, and the reflected light, that is, the light modulated by the information, is detected and converted into an electrical signal. It is converted and sent to preamplifier 5. The signal output from the preamplifier 5 is sent to the video signal reproduction processing circuit 13.
In the audio signal reproduction processing circuit 14, necessary signal processing is performed as appropriate, and desired video and audio signals are obtained as respective outputs.

The position of the pick-up mechanism 3 is moved in three directions by a three-dimensional actuator 4 using, for example, an electromagnetic coil.
Tracking control and jitter correction are performed. First, the output of the preamplifier 5 is sent to the focus control device 6, and according to the focus error output, the pick-up mechanism 3 is moved in a direction perpendicular to the disk 1 via the actuator 4, thereby controlling the distance to the recording surface of the disk 1. to automatically adjust the focus to be optimal. Next, the output of the preamplifier 5 is sent to the tracking control device 7, and according to the tracking error output, the pick-up mechanism 3 is moved in the radial direction of the disk 1, that is, in the width direction of the recording crack, through the actuator 4, so that the light beam is directed to the disk. Tracking is automatically controlled to accurately illuminate the information formed in 1.

While the focus and tracking are controlled in this way, the output of the preamplifier 5 is sent to the low-pass filter 10. This low pass filter 10
The high-frequency video signal and audio signal are removed, and only the low-frequency pilot signal is separated and extracted. This separated pilot signal is sent to the linear velocity control circuit 11, which discriminates its frequency and forms a linear velocity control signal having a voltage value corresponding to the frequency difference from the reference frequency. Alternatively, the separated pilot signal is sent to the linear velocity control circuit 11, and its phase is compared with the phase of the reference signal to form a linear velocity control signal having a voltage value corresponding to the phase difference. By supplying this linear velocity control signal to the disk motor 2 via the motor drive circuit 12, the rotation of the disk 1 is controlled so that the linear velocity is constant.

When the disk 1 rotates at the target linear velocity in this manner, the frequency of the reproduced video signal becomes a predetermined frequency, so that the separation operation of the positive synchronization signal is ensured. Therefore, the video signal reproduction processing circuit 13
The FM-modulated video signal is sent to the horizontal synchronization signal separation circuit 8 to form a pulse signal HD synchronized with the phase of the positive horizontal synchronization signals HD ₁ and HD ₂ . This reproduced and separated horizontal synchronizing signal HD is sent to the jitter control device 9, which compares the phase with a reference signal to detect jitter and form a jitter correction signal. This jitter correction signal is supplied to the actuator 4, and the pickup mechanism 3 is moved in the tangential direction of the recording track of the disk 1, thereby controlling the jitter in the reproduced video signal to be reduced. In FIG. 1, the feed control slider for moving and accessing the entire optical system, such as the pick-up mechanism 3, is not shown.

In the above embodiment, the pilot signal is
It does not necessarily have to be in a synchronous relationship with the video signal.
However, in order to reduce interference to the video signal, it is preferable to define the pilot signal in a synchronous relationship rather than an asynchronous relationship, and furthermore, it is desirable to define the pilot signal so that it is in a frequency interleaved relationship with the video signal.

Furthermore, in the above embodiment, a method was described in which the audio signal is compressed in the time axis and multiplexed within the vertical blanking period of the video signal, but as shown in FIG. It is also possible to record the signal by frequency multiplexing it with an FM modulated video signal. In this case, if the frequency of the pilot signal is selected between the audio signal and the video signal as shown in Fig. 3, the frequency of the pilot signal can be increased, and therefore the frequency of the pilot signal can be increased by frequency discrimination or phase comparison. This is convenient because the sampling rate for detecting linear velocity becomes higher and the gain of the control loop can be increased. However, in this case, it is necessary to remove not only the high-frequency video signal but also the low-frequency audio signal and separate the pilot signal by using a means such as replacing the low-pass filter 10 shown in FIG. 1 with a band-pass filter. arise. For this reason, the range in which the frequency of the pilot signal can be detected is limited, but this does not pose a particular problem since it is sufficient to cover the originally necessary control range of linear velocity. Note that in FIG. 3, an FM modulated audio signal may be used as the audio signal instead of the above-mentioned PCM audio signal.

Furthermore, in the above embodiment, a method was explained in which the video signal is FM modulated and recorded, and the low frequency pilot signal is frequency multiplexed and recorded.
Using a pilot signal with a frequency higher than the frequency band of the paceband video signal shown in Figure 2, both the video signal and the pilot signal are FM modulated and recorded on a disk, and after being FM demodulated during playback, they are passed through a high-pass filter. Removes low-frequency video signals,
The configuration may be such that the high-frequency pilot signal is separately detected.

Further, in the above embodiments, an optical type video disc device has been described, but the present invention is not limited to the optical type and can be applied to other types.

Furthermore, in the above embodiment, the first configuration example was explained in which the linear velocity is controlled to be constant using the reproduced pilot signal, but when the linear velocity falls within a preset range, the positive synchronization signal is separated. signal (frame pulse FP or/and horizontal synchronization signal)
A second configuration may also be used in which the linear velocity control is switched to linear velocity control using HD). Alternatively, a third configuration may be used in which the rotational speed of the disk motor is controlled by the reproduction pilot signal and the rotational phase of the disk motor is controlled by the reproduction synchronization signal. Further, in these second and third configurations, the control using the frame pulse FP may be changed to the control using the horizontal synchronization signal HD.

Furthermore, in the above embodiment, an example was explained in which jitter is detected using the reproduced horizontal synchronizing signal HD. It is also possible to detect and correct jitter. In the case of using a pilot signal for this jitter correction, as shown in FIG. 1, a reproduced pilot signal is supplied to the jitter control device 9 instead of the horizontal synchronizing signal HD, and in this device 9, the phase of the reproduced pilot signal is compared to the reference signal. If the configuration is such that jitter is detected by comparing it with the phase of good. Alternatively, jitter in the reproduced video signal can be eliminated by circuit means such as transmitting the reproduced video signal via a variable delay line using a CCD or the like, and operating the variable delay line using a clock signal formed from the reproduced pilot signal. It is also possible to adopt a configuration that reduces the amount.

〔Effect of the invention〕

As described above, according to the present invention, even when reproducing a video signal having a positive polarity synchronization signal,
Instead of a positive polarity synchronization signal, which is likely to malfunction when the linear velocity fluctuates significantly during startup or access, a pilot signal that can always be detected stably is used, so the video disc remains constant during playback. Rotation can be controlled stably and reliably at linear speeds of In addition, since this pilot signal is recorded and played back on the video disk at a high frequency as a signal in the frequency band between the audio signal and the video signal, the sampling rate when detecting the linear velocity becomes high and the control loop becomes The gain can be increased, and therefore the video disc can be rotated and played back at a constant linear velocity easily, stably and reliably, and a video disc device suitable for high-definition television systems can be obtained. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical video disc device showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing an example of a video signal having a positive synchronization signal according to the present invention, and FIG. FIG. 7 is a diagram illustrating frequency allocation according to another embodiment. 1... Disc, 2... Disc motor, 3...
... Pickup mechanism, 4 ... Three-dimensional actuator, 5 ... Preamplifier, 8 ... Horizontal synchronization signal separation circuit, 9 ... Jitter control device, 10 ... Low pass filter, 11 ... Linear velocity control circuit, 12 ... Motor Drive circuit, 13... Video signal reproduction processing circuit.

Claims (1)

[Claims] 1. The video signal is a signal in a high frequency band, the audio signal is a signal in a low frequency band, and the pilot signal has a frequency between the frequency band of the video signal and the frequency band of the audio signal. A pick-up mechanism includes a video disk on which band signals are respectively superimposed and recorded at a constant linear velocity, and a pick-up mechanism that reproduces each of the above-mentioned signals from the video disk; and a pickup mechanism that separates and detects the pilot signal from the reproduced signal by the pick-up mechanism. a detection means, at least one of a means for discriminating the frequency of the separately detected pilot signal and a means for comparing the phase of the pilot signal with a reference phase, and at least one of the discrimination output and the phase comparison output. 1. A video disc device comprising: first control means for controlling the video disc to a rotational state at a constant linear velocity. 2. The video signal is a signal in a high frequency band, the audio signal is a signal in a low frequency band, and the pilot signal is superimposed as a signal in a frequency band between the frequency band of the video signal and the frequency band of the audio signal. a pickup mechanism for reproducing each of the signals from the video disk; a detection means for separating and detecting the pilot signal from the signal reproduced by the pickup mechanism; at least one of means for discriminating the frequency of the pilot signal and means for comparing the phase of the pilot signal with a reference phase; and at least one of the discrimination output and the phase comparison output. a first control means that controls the disk to rotate at a constant linear velocity; and a second control means that detects the phase of the pilot signal separated and detected by the detection means and performs jitter reduction control using the detected output. A video disc device characterized by comprising means. 3 The video signal is a signal in a high frequency band, the audio signal is a signal in a low frequency band, and the pilot signal is superimposed as a signal in a frequency band between the frequency band of the video signal and the frequency band of the audio signal. a pickup mechanism for reproducing each of the signals from the video disk; a first detection means for separating and detecting the pilot signal from the signal reproduced by the pickup mechanism; a first control means for discriminating the frequency of the separately detected pilot signal and controlling the video disk to a constant linear velocity rotation state based on the discrimination output; a second detection means for separating and detecting the synchronization signal from the signal; a second control means for controlling the pickup mechanism to reduce jitter in accordance with the separately detected synchronization signal; A video disc device comprising at least one of the following: third control means for controlling the rotational phase of the video disc according to a signal.