JPS585460B2 - Ritsutaion Kiyou Enban Record Donioker Kirokushingouno - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a novel method for optically picking up recorded signals in a 45-45 stereophonic disc record, in which stereophonic signals are individually engraved and recorded on both walls of a sound groove. This is an attempt to provide a pickup method.

The most common method used to pick up recorded signals from a disc record is to trace a playback stylus into the sound groove of the disc record, and move the playback stylus according to the recorded signal engraved in the sound groove. This method converts mechanical vibrations into electrical signals, but this method has many drawbacks, such as the sound groove being destroyed unless the mechanical impedance of the signal pickup means is small.

The drawbacks of the conventional pickup means described above can be overcome by adopting a means of optically picking up the recording signal engraved and recorded in the sound groove of a disc record. Many attempts have also been made to optically pick up recording signals from records.

When optically picking up a recording signal from a disc record, a light spot (light spot) whose diameter is sufficiently small compared to the shortest recording wavelength of the recording signal engraved in the sound groove of the disc record is used. It is necessary to always project a light spot onto the sound groove, but since disc records generally have warps and uneven thickness, it is necessary to always project a spot of light with a minute diameter onto the sound groove. In order to achieve this, a focus servo system must be installed, and since disc records usually have eccentricity or deviation from a perfect circle, it is necessary to always project a spot of light with a minute diameter onto the sound groove. In order to do this, a tracking servo system must be provided in addition to the focus servo system described above.

Even if the disc record is warped, uneven in thickness, eccentric, or out of roundness, the present invention uses automatic control operations by the focus servo system and tracking servo system to create a spot of light with a minute diameter. We focused on the fact that the two servo systems described above, which can perform operations such as always projecting sound onto the sound groove, have sufficient tracking characteristics even in the lower frequency range than the audible frequency range. A new optical system that uses error signals obtained individually from the detection parts of the two servo systems, which do not track above the band, to obtain individual recording signals carved on both walls of the sound groove. The pickup method is provided, and the specific contents thereof will be clarified below with reference to the attached drawings.

FIG. 1 is an enlarged vertical cross-sectional view of a part of a disc record D, and in the figure, G is a sound groove.

Individual recording signals are recorded on both wall surfaces 1.degree. 2 of the sound groove G of a 45-45 stereophonic disc record in such a manner that the wall surface of the sound groove is displaced in the direction of the arrow in the figure.

In addition, what is indicated by an imaginary line P in Fig. 1 is the sound groove G.
In addition, Pa is a light beam with a minute diameter, and numeral 3 indicates the bottom of the sound groove G.

Figure 2 shows the case where recording signals of the same frequency and the same phase are recorded at the same signal level on both walls 1 and 2 of the sound groove G of a 45-45 stereophonic disc record, and when the recording signals are the same at the same signal level and the same phase. frequency.

When recording signals with opposite phases are recorded,
45 is a diagram showing the manner of displacement of both wall surfaces 1 and 2 of the sound groove;
-45 system stereophonic sound record, according to the standard, if two signals of the same frequency, the same phase, and the same signal level are respectively recorded as recording signals on both wall surfaces 1.2 of the sound groove G, the sound groove G The bottom part 3 of the sound groove G reciprocated between A and D shown in FIG. In this case, the bottom portion 3 of the sound groove G is set to reciprocate between a and C shown in FIG.

The above-mentioned displacement of the bottom 3 of the sound groove G can be easily detected by using various focus servo systems or tracking servo systems of known configuration used in so-called optical video disk players. Can be done.

By the way, the bottom part 3 of the sound groove G is also displaced due to the eccentricity or warpage of the disc record, and the presence of deviation from a perfect circle.
Generally, the rate of change over time in the displacement of the bottom part 3 of the sound groove G caused by eccentricity, warpage, and deviation from a perfect circle in a disc record is about 10 to 20 times the basic rotational frequency of the disc record. Since it falls within the frequency and wave number range, it can be used as a focus servo system or a tracking servo system within the range of 10 to 20 of the basic rotational frequency of a disc record.
Any device that can perform a faithful tracking operation within a frequency range that is approximately double that is sufficient.

Now, if we consider the case where a disc record rotates at 33 1/3 revolutions per minute, the follow-up characteristic required for the focus servo system and tracking servo system described above is 10 Hz.
This frequency range is within the frequency range lower than the audible frequency range, so the focus servo system and tracking servo system are designed to perform slow control operations in the frequency range lower than the audible frequency range. Then, the error signals obtained from each of the focus servo system and the tracking servo system can be correlated with the displacement of the bottom 3 of the sound groove G caused by the recorded signals recorded on both walls 1 and 2 of the sound groove G. Become what you have.

FIG. 3 is a block diagram of an embodiment of an optical pickup system for recording signals in a three-dimensional sound record of the present invention. In the figure, F is a focus servo system, T is a tracking servo system, and 4 and 5 are bandpass filters that pass signals in a required frequency band; 6 is an inverter; 7 and 8 are mixing amplifiers; and 9 and 10 are output terminals.

Hocus servo system F1 and tracking servo system T
, Fa and Ta are detection sections, FfTf is a low-pass filter, Fc and Tc are control sections, and the detection power from the detection sections Fd and Td is, for example, a low-pass filter that passes only signal components of 10 Hz or less. Control units Fc, T through filters Ff, Tf
c, the controllers Fc and Tc use the above-mentioned 1.
In response to signal components below 0 Hz, for example, the position of the focusing lens or the angle of an optical path changing member such as a half mirror is moved, and the light is adjusted so that a spot of light with a minute diameter is always projected into the sound groove. Control the beam.

The control units Fc, Tc, etc. may have 10
If the device responds only in a frequency band below Hz, the low-pass filters Ff and Tf described above are not necessary.

Furthermore, a signal phase corrector may be provided as necessary in the path of the signals applied from the detection units Fa, Ta to the control units Fc, Tc.

The detection forces (error signals) from the detection parts Fa and Ta in the hocus carbo system F and the tracking servo system T are as follows:
They are applied to bandpass filters 4 and 5, respectively, which pass signals in required frequency bands.

The passband characteristics of the bandpass filters 4 and 5 described above are those that allow signal components in the audible frequency band to pass when the three-dimensional sound record to be played is a normal two-channel stereo record. Also, the stereophonic record to be played is the so-called CD-4.
In the case of a 4-channel stereo record such as the 4-channel stereo record system, it is sufficient to allow signal components in the audible frequency band and ultra-audible frequency band to pass through.

It goes without saying that a high-pass filter may be used instead of the bandpass filter 4.5.

The signal that has passed through the bandpass filter 4 is sent to a mixing amplifier 7.
．． The signal that has passed through the bandpass filter 5 is applied directly to the mixing amplifier 8 and is applied to the mixing amplifier 7 via the inverter 6.

In the optical pickup system configured as above,
The principle by which recording signals recorded individually on both walls of a sound groove in a stereophonic record are outputted individually from the output terminals 9 and 10 will be explained below with reference to FIG. 4 as well.

FIG. 4 is an enlarged view of a part of FIG. When two signals at the signal level are recorded as recording signals, the bottom part 3 of the sound groove G shows movement in a manner of reciprocating between 3 and d, so in this case, in the focus servo system F, No signal is detected, and only the tracking servo system T detects the signal.

Therefore, the signals sent from the tracking servo system T through the bandpass filter 4 are equally applied to the mixing amplifiers 7 and 8, and the output terminals 9 and 10 have the same frequency, the same phase, and
Signals with the same signal level are sent out.

Next, when two signals with the same frequency, opposite phase, and the same signal level are recorded as recording signals on each wall surface 1, 2 of the sound groove G, the bottom 3 of the sound groove G is between a and c. In this case, contrary to the case described above, no signal is detected from the tracking servo system T, and a signal is detected only from the focus servo system F. .

Therefore, the signal sent from the focus servo system F via the bandpass filter 5 is applied directly to the mixing amplifier 8, and is applied to the mixing amplifier 7 via the inverter 6, so the output terminal Signals 9 and 10 have the same frequency, the same signal level, and opposite phases.

Furthermore, when the recording signal is recorded only on the wall surface 2 on one side of the sound groove G, the bottom part 3 of the sound groove G is
It shows movement in a manner of reciprocating between r and f.

Therefore, in this case, the tracking servo system T
The detection section Td detects the components ij in FIG. 4 as a signal, and the detection section Fd of the focus servo system F detects the components hg in FIG. 4 as a signal.

Among the signals from the detection units Td and Fd in each of the servo systems described above, the signal from the detection unit Td that has passed through the bandpass filter 4 is directly added to the mixing amplifiers 7 and 8, while the signal from the detection unit Fd The signal that has passed through the bandpass filter 5 is applied directly to the mixing amplifier 8 and also to the mixing amplifier 7 via the inverter 6.
The signal sent from the mixing amplifier 7 to the output terminal 9 is the one in which the above-mentioned ij component and hg component signals of the same phase and the same signal level are added, and the signal sent from the mixing amplifier 7 to the output terminal 9 is as follows. One of the signals of the above-mentioned ij and hg components having the same phase and the same signal level is added with its polarity inverted, that is, there is no signal.

As can be seen from the explanation of the operating principle illustrated with reference to FIG. 4, the optical pickup system of the present invention utilizes the detection force from the focus servo system T and tracking servo system , the recorded signals recorded individually on both wall surfaces of the sound groove G can be extracted individually optically, and in order to extract the signals on both wall surfaces of the sound groove individually,
There is no need to use two dedicated photodetectors.

Since the output signals obtained from the output terminals 9 and 10 described above correspond to the R signal and L signal obtained from a normal mechanical pickup, the signals obtained from the output terminals 9 and 10 are used in the three-dimensional sound reproduction device. It goes without saying that if it is applied to the pickup terminal, it is possible to reproduce 2-channel or 4-channel stereophonic sound.

As described above, according to the optical pickup method of the present invention, three-dimensional images can be obtained by using error signals obtained from the focus servo system and the tracking servo system without using a special photodetector for picking up signals. Since an acoustic signal can be obtained, a pickup device with a simple configuration and excellent characteristics can be provided.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view of the sound groove of a disc record, Figs. 2 and 4 are explanatory diagrams of the displacement of both walls and the bottom of the sound groove in a 45-45 disc record, and Fig. 3 is a diagram of the sound groove of the present invention. FIG. 2 is a block diagram of one embodiment of an optical pickup system. D...Disc record, G...Sound groove, P...Light beam, 1
, 2...Wall surface of sound groove G, 3...Bottom of sound groove, F...Hocus servo system, T...Tracking servo system, Fa
, Ta... detection section, Ff. Tf...Low pass filter, Fc, Tc...Control unit, 4.5...
... Bandpass filter, 6 ... Inverter, 7, 8 ... Mixing amplifier, 9, 10 ... Output terminal.

Claims (1)

[Claims] 1. The sound groove of a 45-45 type stereophonic disc record, in which stereophonic signals are individually engraved on both walls of the sound groove, is configured such that control operations are performed in a frequency band lower than the audible frequency band. A light beam that is automatically controlled by the focus servo system and tracking servo system is projected to track the sound groove with a minute light spot, and each of the signals obtained from the detection section of each servo system described above is An optical pickup method for recording signals in a three-dimensional acoustic record, in which recording signals recorded individually on both walls of a sound groove are obtained by determining the sum and difference of other required signal components.