JPS61245682A - Video disk player - Google Patents

Abstract

PURPOSE:To prevent reproduction from being executed in a malfunction state by switching automatically an FM demodulating output characteristic in accordance with the kind of a loaded disk. CONSTITUTION:An FM signal recorded in a disk 2 is detected by a pickup 1, applied to an FM demodulator through a pre-amplifier 3 and a band amplifier 4 and a demodulating output is led out to an output terminal 13 through a changeover switch 6, a low-pass filter 8 (or 0), a de-emphasis circuit 10 (or 11) and a switch 7. The low-pass filter 8 and the de-emphasis circuit 10 have a frequency band characteristic conforming with the recording signal of a standard disk and the low-pass filter 9 and the de-emphasis circuit 11 have a wide band characteristic conforming with the recording signal of a high quality disk. A disk discriminating circuit 12 switches the changeover switches 6, 7 in accordance with the kind of a loaded disk.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a video tape recorder capable of playing back both high-definition discs and standard discs.

<Summary of the Invention> The present invention identifies the type of loaded disc and automatically switches the FM demodulation output characteristics according to the content, making it possible to play both high-quality discs and standard discs. be.

<Prior art> Generally, in a video disc, video and audio signals are
The signal is modulated and recorded as uneven signals (pits) along a spiral recording groove (hereinafter referred to as a track).

Then, in the reproducing player, the disc recording signal is detected optically as a change in intensity of the reflected light of the focused light beam, or as a change in capacitance using a sensor equipped with an electrode.

Currently, the FM frequency band of standard discs recording standard television signals such as NTSC and PAL is 6.
1-7.9 MHZ, or 7.6-9.3 MH2
Therefore, in the reproduction system, the luminance signal band is 3.1M each as the band to which the upper and lower FM sidebands are forcefully applied.
In the case of H2, 4, 2 MH2, 3.6 to 111 M) (Z or 3,9 to 13.5 MH7. (Refer to the grooved capacitance type Nuvectorum shown in Figure 2) - Blade High Definition Television The luminance signal band of the signal is 8.1M even after band compression.
Hz is required.

Figure 3 shows an example of the FM Nuvectorum when recording this on a high-quality disc.
~1.5 MHz, the band covering the upper and lower sidebands is 0.9 to 24.1 MHz, which is wider than the standard television signal described above.

<Problems to be Solved by the Invention> For this reason, when playing two types of discs, a standard disc and a high-quality disc, in one video disc player, two types of playback circuits with different frequency bandwidths are usually used. system, and it was necessary to switch the playback circuit depending on the type of playback disc.

<Means for Solving the Problems> The present invention has been made in view of the above points, and it is possible to determine the type of loaded disc, that is, whether a high-quality disc or a standard disc is loaded in a shredding player. In addition to providing disc identification means for identifying the
A characteristic switching circuit for switching the frequency characteristic of the M demodulated output is provided.

<For work 1> This allows the FM demodulation output characteristics to be automatically switched according to the type of loaded disc based on the disc identification output.

<Example> FIG. 1 shows an example of the present invention.
is a pickup, 2 is a disk, 3 is a preamplifier, 4 is a band amplifier, 5 is an FM demodulator, 6°7 is a changeover switch,
8.9 is low pass filter, ]0. ]lj: de-emphasis circuit, 12 is a disk identification circuit, and 13 is an output terminal. Note that the tracking servo circuit, audio signal processing circuit, video signal processing circuit, etc. that are necessary for an actual player are not particularly relevant to the present invention and are therefore omitted.

Now, the pickup 1 detects the FM signal pre-recorded on the disk 2, and the FM signal is detected as 0. A preamplifier 3 with a wide band of ~25 MHz amplifies the signal by about 46 dB, and a downstream band amplifier 4 separates and amplifies the upper and lower FM sideband components.

The band of the band amplifier 4 is assumed to be 1 to 23 MHz, which corresponds to a high-quality disk with a wide band, since it can be used commonly with standard disks and high-quality disks. Next, this amplified FM signal is applied to an FM demodulator 5, where it is FM demodulated, and then passed through a changeover switch 6 to a low-pass filter 8 (
or 9) to reproduce the baseband video signal and further de-emphasis circuit 10 (or 11).
), the high-frequency components are attenuated according to the brienfacine in the recording system, and thus F.

The frequency characteristics of the M demodulated output are corrected. In many cases, the low-pass filter 8 and de-emphasis circuit 10 have frequency band characteristics as shown in FIG. It has wideband characteristics as shown in FIG. 5 that are suitable for recording signals.

On the other hand, the disc identification circuit 12 performs a switching operation of the changeover switch 6.7 based on the identification output of the type of the loaded disc. The method for identifying the type of disc, that is, whether it is a standard disc or a high-quality disc, is to attach or remove it from the player together with the disc, or to make a notch in advance on the rad plate that corresponds to the disc, and to detect this notch. You can identify whether it is a standard disc or a high-quality disc by doing this. Alternatively, a digital code signal representing the type of the disc may be recorded in advance during the vertical blanking period of the disc, and this may be read and identified by the disc identification circuit 12 during playback.

When a standard disk is loaded, the selector of the selector switch 6.7 is connected to the contact ■ side as shown in the figure, based on the identification output from the disk identification circuit 12, and in this case, the F
The demodulated output from the M demodulator 5 is led out to the output terminal 13 via the switch 6, the low-pass filter 8.14177777 circuit]0, and the switch 7.

On the other hand, when a high-quality disc is loaded, the changeover switch 6.7 is switched to the contact ■ side, and at this time the FM
The demodulation output is controlled by a selector switch 6, a low-pass filter 9, and a de-emphasis signal of 1% 11. ! 'The signal is output to the output terminal 13 via the changeover switch 7.

In this manner, in this embodiment, the type of the loaded disc 2 is identified by the disc identification circuit 12, and the changeover switch 6.7 is automatically operated in accordance with the identification output. 9 and de-emphasis ntllO, 11 perform a predetermined band correction operation according to the type of disc, and then output from the output terminal 13. This output signal is subjected to appropriate signal processing operations such as dropout correction, color subcarrier frequency conversion, and time base correction in a video signal processing circuit (not shown) at the subsequent stage. It is output as a color television signal or a high-definition color television signal.

<Effects of the Invention> As described in Section 2 below, according to the video disc player of the present invention, the frequency characteristics of the FM demodulation output are automatically switched according to the type of disc loaded, so no switching operation is required. There is no risk of playback under incorrect operating conditions.

[Brief explanation of drawings]

Fig. 1 is a block diagram of one embodiment of the video disc player of the present invention, Fig. 2 is a recording signal spectrum of a standard disc, Fig. 3 is a recording signal nupectrum of a high-quality disc, and Figs. 4 and 5 are the above FIG. 3 is a frequency characteristic diagram of two low-pass filters used in the example. 1 pickup, 2 disc, 5...F
M demodulator, 6, 7 - changeover switch, 8, 9... low pass filter, 10.11 de-emphasis circuit, 12 - disc identification circuit. Agent Patent attorney Aihiko Fuku (and 2 others) - Ichiyu Kazuen Ko 1 Figure 5 θ\θ/MHz

Claims (1)

[Claims] 1. In a video disc player capable of playing both high-definition television signal recording video discs (hereinafter referred to as high-definition discs) and standard television signal recording video discs (hereinafter referred to as standard discs). , a disc identification means for identifying whether the loaded disc is a high-quality disc or a standard disc, an FM demodulation means for FM demodulating a signal picked up from the disc, and a stage subsequent to the FM demodulation means. and a characteristic switching means for switching the frequency characteristic of the FM demodulation output according to the identification output from the disc identification means provided therein, so that the FM demodulation output characteristic is automatically switched according to the type of the loaded disc. A video disc player featuring: