JPS5811683B2 - Tracing Hizumi Hosesouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a delay method to remove tracing distortion that occurs between the disc groove and the playback stylus when playing back a disc record on which multi-channel signals are recorded. This invention relates to an improved tracing distortion correction device.

Conventionally, a tracing error occurs when a playback needle traces the sound groove of a disc record that records a stereo signal, but in order to eliminate this tracing error, a correction method using delay modulation has been proposed. This is the special public service from 1974
This method is publicly known from Publication No. 40343 and the like.

According to this publication, tracing distortion is based on the idea that when the playback stylus traces the sound groove of a disc record, the change in the contact point where the playback stylus contacts the sound groove wall undergoes a type of delay modulation. When recording music, a delay modulation component corresponding to the tracing distortion experienced during playback and an inverse delay modulation component are added.The device has the configuration shown in Figure 1. It has become.

That is, in FIG. 1, 1 is a terminal to which an input signal is applied, and to the input signal, a controlled signal to be corrected for distortion due to a tracing error is applied.

2 is a control signal input terminal.

These controlled signals and control signals are applied to a delay modulation circuit 5 through phase shift circuits 3 and 4, and output from an output terminal 6 to reverse the delay modulation component caused by the change in the contact point where the reproducing needle contacts the disc groove. The corrected output is extracted.

The correction waveform extracted by the above-mentioned device needs to be faithfully transmitted as a vibration waveform of the cutter needle tip, but if there is phase distortion in the system from the correction device to the cutter needle, the correction waveform will be disturbed and distorted. A problem arises in that the correction effect is reduced.

In order to compensate for this phase distortion, the conventional solution was to provide a phase shift circuit 3°4 between the input signal to the delay modulation circuit 5 and the control signal, and create a phase difference between the two signals. .

If this method is directly applied to a carrier multiplexed record such as a carrier desk, the following problems will occur.

(1) Since the phase shift circuits 3 and 4 provided to create a phase difference do not have linear phase-frequency characteristics, the angle-modulated carrier wave undergoes phase distortion after passing through the phase shift circuit, resulting in a demodulated waveform during playback. distortion increases, making playback practically impossible.

(2) Since the input signal to the delay modulation circuit of the correction device is a composite signal in which the angle-modulated carrier wave is superimposed on the direct signal, a phase disturbance occurs between the direct signal and the modulation signal, resulting in multi-dimensional This greatly deteriorates the separation between channels during playback, making playback impossible.

In order to eliminate the above drawbacks, the present invention provides tracing error correction using a delay modulation method by creating a phase between an input signal and a control signal without using phase shift circuits 3 and 4 when producing carrier wave multiplexed records. The aim is to perform phase compensation from the device to the cutter system.

An example configuration of the present invention will be described below with reference to FIG.

FIG. 2 shows a system diagram of the present invention, in which a subchannel signal is applied to terminal 7, and a direct signal is applied to terminal 9.

8 is a modulation circuit, and the subchannel signal is transmitted through the modulation circuit 8.
Then, the carrier wave is angle-modulated and then applied to the adder circuit 11.

On the other hand, the direct signal is applied to the adder circuit 11 through the low-pass filter circuit 10.

The output of this adder circuit 11 is a composite signal in which the carrier wave angle-modulated by the sub-channel signal is superimposed with the direct signal, and is used in the tracing distortion correction device using the delay modulation method shown on the right side of the dashed-dotted line in FIG. Added.

This composite signal is sent to the delay circuit 12 for fine phase difference adjustment.
The signal is then applied to a delay modulation circuit 14 similar to the delay modulation circuit 5 shown in FIG.

On the other hand, as a control signal, a direct signal from the previous stage of the low-pass filter circuit 10 is applied to the delay modulation circuit 14 through the phase compensation delay circuit 13 and the phase compensation low-pass filter circuit 15. .

The output of the delay modulation circuit 14 is guided from an output terminal 16 to a cutter (not shown).

According to the above configuration of the present invention, the phase compensation of the cutter system is performed by the block indicated by the dotted line 17.

That is, the direct signal before multiplexing is made into a control signal via the delay circuit 13 and the phase compensation low-pass F-wave circuit 15,
The direct signal system is provided with a band-limiting low-pass F-wave circuit 10 and a delay circuit 12 having a cutoff frequency different from that of the phase compensation low-pass filter circuit 15, and these direct signals (input signals) and control signals are provided. A phase difference is created between the cutter and the cutter to compensate for the phase error in the cutter system.

That is, if the phase characteristics of the cutter system connected to terminal 16 in FIG. 2 are made to have high frequency characteristics as shown by curve 18 in the phase-frequency characteristics of FIG. 3, linear delay characteristics can be obtained. It is clear that it is sufficient to form a curve 20 of the difference from that shown by the straight line 19 shown in FIG.

Therefore, in the present invention, each element within the block indicated by the dotted line 17 may be used to perform correction as shown in the curve 21 shown in FIG.

That is, in the frequency-phase characteristic curve shown in FIG. 4, the phase characteristic of the low-pass lachrymal fluid circuit 10 for band limiting of the direct signal is selected as shown in the curve 26, and the phase compensation with a higher cutoff frequency is selected. The phase characteristics of the low-pass lachrymal fluid circuit 15 for
The phase compensation delay circuit 13 is selected as shown in the curve 22.
When the phase characteristic of the control signal system is shown by a straight line 23, the phase characteristic of the control signal system becomes a curve 24. Therefore, the phase difference between the curve 24 and the curve 26 is the difference between the input signal g of the Norinobe modulation circuit 14 and the control signal. Therefore, the phase difference between the curve 24 and the curve 26 may be selected so that it becomes the curve 21 in FIG. 3.

Furthermore, here, the curve 25 is the delay characteristic of the delay circuit 12.

As described above, according to the present invention, in the composite signal to be recorded, the input signal of the tracing distortion correction device using the delay modulation method and the it1# signal can be combined without inserting a circuit that causes phase disturbance. The phase difference between them can be compensated for arbitrarily.

With this, it is possible to greatly improve the deterioration of the distortion removal effect due to the phase error of the cutter system.

Furthermore, according to the present invention, when compensation for tracing errors is performed, tracing can be performed without increasing demodulated signal distortion or deteriorating channel separation due to phase distortion when a phase shifter is inserted into a composite signal system. It has the characteristics of being able to improve time distortion and crosstalk to the direct channel, and making it possible to produce high-quality multidimensional stereophonic records.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a conventional tracing distortion correction device using delay modulation, Fig. 2 is a system diagram of a tracing distortion correction device of the present invention, and Fig. 3 shows phase characteristics and cutter system using a phase compensation circuit. Phase Characteristic Diagram FIG. 4 is a phase characteristic diagram of the phase compensation circuit. In the figure, T, 3 and 4 are phase shift circuits, 5 is a delay modulation circuit, 8 is an angle modulator, 10 is a low-pass F-wave circuit for direct signal band limitation, 11 is an adder circuit, and 12 is a delay circuit for fine adjustment. ,1
Reference numeral 3 indicates a delay circuit for phase compensation, 14 a delay modulation circuit, and 15 a low-pass filter circuit for phase compensation.

Claims (1)

[Claims] 1 Pass each of the input signal and the control signal through a low-frequency F-wave circuit and a delay circuit, and appropriately select the cut-off frequency and cut-off characteristics of the low-frequency mud wave circuit and the delay time of the delay circuit to match the input signal and the control signal. A tracing distortion correction device using delay modulation, which performs delay modulation by setting a phase difference between the control signal and the control signal.