JPS6224873B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc-shaped information recording medium and a method for reproducing the same, which selectively selects two audio carrier waves in a main information signal recorded on the disc-shaped information recording medium and reproduced from the disc-shaped information recording medium. It is an object of the present invention to provide a recording medium that can be used to inform the recording start position and recording end position of a signal, and a method for reproducing the same.

Conventionally, a disc-shaped information recording medium (hereinafter referred to as a "disc") such as a video disc is obtained by recording video signals and audio signals on a disc-shaped recording medium as a change in the so-called geometric shape of a row of pits intermittently. It is known to play this. In such a disc, as shown in FIG. 1, information signals are recorded within the range indicated by _B2 , and information signal-free bands are provided in _B1 and _B3 before and after the range B2. Here, since the length of the information signal recording band _B2 varies depending on the content of the recording program, the length of the recording band B2 is changed in order to immediately start returning the reproducing element such as the reproducing needle to the standby position such as the armrest after the information signal reproduction is finished. ₂ and no record band B ₃
A return signal (so-called go-home signal) is recorded between the two. Furthermore, in order to quickly reach the recording start position of the recording program, a so-called lead-in signal is recorded between the non-recording band _B1 and the recording band _B2 .

However, the conventional go-home signal and lead-in signal recorded signals unrelated to the form of the information signal recorded on _B2 , and therefore each required a dedicated demodulation circuit, which resulted in an expensive signal. Ta.

The present invention eliminates the above-mentioned drawbacks, and one embodiment thereof will be described with reference to the drawings from FIG. 2 onwards.

FIG. 2 is a diagram showing an example of the frequency spectrum of a signal recorded on the disk-shaped information recording medium of the present invention and reproduced by the method of the present invention; FIG.
B shows an example of the frequency spectrum of a go-home signal and a lead-in signal. Here, the disk recorded in this embodiment is the disk previously proposed by the applicant, that is, the main track on which color video signals and audio signals are recorded spirally without forming a needle guide groove, and this disk. First and second tracking control reference signals are provided on the disk 1 approximately in the middle between the center lines of adjacent tracks of the main track.
A sub-track is formed which is optically switched every rotation period and recorded in chronological order, and a main or sub-track corresponding to the switching/recording connection position portion of the first and second tracking control reference signals is formed. An explanation will be given by taking as an example a disk in which a third tracking control reference signal is recorded on the sub-track.

Here, the recorded portions of the main and sub-tracks are _B2 shown in the first diagram, and the recording signal of the main track is, for example, the upper limit of the luminance signal in the NTSC color video signal, as shown in FIG. The frequency is approx.
A luminance signal in a band limited to 3MHz and a carrier color signal in a band of 2.56MHz±500KHz whose color subcarrier frequency is low-pass converted to 2.56MHz (=5/7 x 3.58MHz) are band-sharing multiplexed. For example, a first audio carrier wave with a band of 3.43MHz ± 75KHz obtained by frequency modulating a 3.43MHz carrier wave with a first audio signal, and a second audio signal with a 3.73MHz carrier wave are added to the synthesized color video signal obtained by 3.73MHz± obtained by frequency modulating the signal
A mixed signal is obtained by frequency division multiplexing the second audio carrier wave in the band of 75 KHz, and this mixed signal is further frequency modulated and recorded.

The present invention focuses on the above recording signal, and records a 3.43 MHz carrier wave' as a go-home signal in the first part of the non-recording band _B3 shown in the first diagram, as shown in the frequency spectrum of FIG. 3A. , and a carrier wave of 3.73 MHz is recorded in the non-recording band _B1 as a lead-in signal as shown by '' in FIG. Here, the carrier waves ',' may be modulated.

FIG. 4 shows a block diagram of an embodiment of the method of the present invention. In the figure, 1 is an input terminal, at which the mixed signal shown in Fig. 2 is frequency modulated and recorded on the main track, and the signals shown in Fig. 3 A and B are frequency modulated as a go-home signal and a lead-in signal. From the disk (not shown) of an embodiment of the present invention recorded with Reproduction is performed by taking advantage of the change in the frequency, and a frequency demodulated output of the resulting reproduced signal is supplied.

The band filter 2 separates and extracts only the first audio carrier wave and outputs it to the FM detector 4. On the other hand, the band filter 3 separates and extracts only the second audio carrier wave and outputs it to the FM detector 5. FM
The output signal of the wave detector 4 is outputted from an output terminal 6, and is also supplied to a carrier detector 8, where the presence or absence of a carrier is detected. Further, the output signal of the FM detector 5 is output from the output terminal 7 and is also supplied to the carrier detector 9. Carrier detectors 8 and 9 detect the first and second audio carriers at 3.43 MHz, respectively.
It detects the presence or absence of the 3.73MHz component and outputs a signal for muting the sound output only when there is no carrier wave.

The above circuit shown in FIG. This is determined to be home signal reproduction. That is, normally, when the main track is being reproduced, no muting detection output is taken out from the output terminals 10 and 11, but for example, at the position where the recording program has finished being reproduced, there is a 3.43 MHz signal indicated by '' in FIG. 3A. Since only the carrier wave is recorded and the 3.73 MHz carrier wave is not recorded, the muting detection output is taken out only from the output terminal 11. As a result, the regeneration device immediately moves the regeneration needle toward the armrest position.

Similarly, since the muting detection output is taken out only from the output terminal 10 at the start of disc reproduction, it is determined that the lead-in signal has been reproduced, and the reproduction needle is quickly moved to the recording position of the recording program.

As described above, according to this embodiment, the lead-in signal and the go-home signal can be detected by sharing the audio demodulation system, and the structure can be made cheaper than the conventional one. It should be noted that the numerical values in the above embodiments are merely examples, and it goes without saying that the present invention is not limited to these.

As described above, the disc-shaped information recording medium and the method for reproducing the same according to the present invention provide a first audio recording band immediately before a main information signal recording band formed by recording a main information signal including first and second audio carrier waves. record the carrier wave,
Immediately after this recording band, a disk-shaped information recording medium is created in which a second audio carrier wave is recorded, and when the disc-shaped information recording medium is reproduced, a first audio carrier wave is detected, respectively, for the presence or absence of the first and second audio carrier waves of the audio demodulation system of the playback device. When only the detection output of the first audio carrier wave is received from the second detector, this is reproduced as a lead-in signal, and when only the detection output of the second audio carrier wave is received, this is reproduced as a return signal. Since the audio demodulation system in the existing reproducing device can be used in common, and a dedicated circuit for reproducing the lead-in signal and return signal is not required, the reproducing device can be constructed at low cost.

[Brief explanation of the drawing]

Fig. 1 is a side view of a main part of a disk for explaining the recording positions of a lead-in signal and a return signal (go-home signal), and Fig. 2 is an example of recording and reproduction signals of a disk to which the method of the present invention can be applied. Frequency spectrum diagrams illustrating examples, FIGS. 3A and 3B, respectively, show an example of a go-home signal and a lead-in signal that are recorded on the disk-shaped information recording medium of the present invention and reproduced by the method of the present invention. frequency spectrum diagram,
FIG. 4 is a block diagram showing an embodiment of the regeneration method of the present invention. 1... Reproduction signal input terminal, 2, 3... Band filter for audio carrier separation and extraction, 6, 7... Audio detection output terminal, 8, 9... Carrier detector, 10, 1
1...Detection output terminal for muting.

Claims (1)

[Claims] 1. A first audio carrier wave is recorded immediately before a main information signal recording band formed by recording a main information signal including first and second audio carrier waves, and immediately after the recording band. 1. A disc-shaped information recording medium, characterized in that a second audio carrier wave for starting a reproducing element to return to a standby position is recorded thereon. 2. The first audio carrier wave is recorded immediately before the main information signal recording band formed by recording the main information signal including the first and second audio carrier waves, and the reproducing element is placed on standby immediately after the recording band. When reproducing a disc-shaped information recording medium on which a second audio carrier wave for starting a return to the position is recorded, first and second audio carrier waves of the audio demodulation system of the reproducing device detect the presence or absence of the first and second audio carrier waves, respectively. When only the detection output of the first audio carrier wave is received from the second detector, this is reproduced as a lead-in signal, and when only the detection output of the second audio carrier wave is received, this is reproduced as a return signal. A method for reproducing a disc-shaped information recording medium, the method comprising: reproducing a disc-shaped information recording medium;