JPS6163186A - Magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To adopt the heterodyne audio frequency system to simplify a low frequency circuit for recording and improve amplitude and phase characteristics by performing the frequency modulating/demodulating operation with a frequency higher than the frequency of a frequency modulated audio signal recorded on a magnetic tape. CONSTITUTION:Right and left audio signals processed by an audio input circuit 3s are applied to frequency modulating circuits 41 and 42 and have frequencies modulated by a prescribed frequency and are added by an adder 5 and have frequencies converted in frequency converters 6a and 6b by pilot signals. These frequency modulated signals are processed in LPF circuits 8a and 8b, adders 11a and 11b, etc. in succeeding stages and are recorded on a magnetic tape 2. Reproduced audio signals are inputted to BPF circuits 15a and 15b and changeover switches 17a and 17b of a reproducing circuit, and the pilot signals from oscillators 7a and 7b are applied to frequency converters 16a and 16b similarly to converters 6a and 6b of a reproducing system. Thus, the heterodyne audio frequency modulating/demodulating operation is performed, and the audio frequency system is adopted to simplify the low frequency circuit for recording and improve amplitude and phase characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device that further improves audio recording characteristics.

[Conventional technology]

In order to make the audio recorded on the magnetic tape used for video recording high-fidelity, it is used in a frequency band between the luminance signal that has been modulated by one frequency and the chromaticity signal that has been low-frequency converted.

Multiplex recording of frequency modulated audio signals. A so-called frequency multiplex recording type magnetic recording/reproducing device has been proposed. When recording 2-channel audio using frequency modulation, 1 is originally 2.
A Pi-class audio carrier wave is required, but if the video track is a β method in which signals are recorded using the guard panless alimath recording method, the frequency of the audio carrier wave must be changed on the @-contact track to avoid interference from adjacent tracks. 150k
Hz shifted, '1.38Mtlz and 1.68Mtl
The track where the audio carrier wave of z is recorded and 1.53MHz
and 1.83MHz sound 1j1i! i! The tracks on which the transmitted waves are recorded are arranged alternately.

[Problem that the invention seeks to solve]

The conventional magnetic recording/playback device described above records four types of audio signals with different carrier frequencies in a limited frequency band between the luminance signal and the chromaticity signal, so the frequency transition width of the audio signal for each channel is also limited. Unlike luminance signals, which have limitations and can be recorded using a saturation magnetic recording method, audio recording is performed using an AC bias recording method, which poses problems such as difficulty in obtaining flat frequency characteristics and a high S/N ratio.

Furthermore, when video recording is not performed, there are problems such as the fact that even though the recording band for luminance signals is vacant, this recording band cannot be used effectively.

[Means for solving problems]

This invention solves the above problems.

A magnetic recording system that uses a predetermined frequency band between the frequency-modulated luminance signal and the low-frequency converted chromaticity signal to multiplex the frequency-modulated audio signal, and records the multiplexed signal on a magnetic tape. The playback device includes a frequency modulation circuit that frequency-modulates the audio signal using an audio carrier wave having a higher frequency than the predetermined frequency band, and a frequency modulation circuit that modulates the frequency of the audio signal using the audio carrier wave having a frequency lower than the audio carrier wave. and a frequency converter that converts the frequency using a pilot signal whose frequency is set higher than the audio frequency modulation signal in the predetermined frequency band recorded on the magnetic tape, and the audio signal frequency-converted by the frequency converter. a low-frequency F-wave circuit that generates a low-frequency P wave to extract the audio frequency modulation signal component to be recorded on the magnetic tape; The gist of the present invention is to provide an audio recording means for recording on a magnetic tape using the frequency band of the signal.

[Effect]

This invention performs modulation and demodulation at a frequency sufficiently higher than the frequency of the frequency-modulated audio signal recorded on the magnetic tape, and when not recording a luminance signal on the magnetic tape, the modulation and demodulation operation is performed at a sufficiently high frequency. Audio No. 13 is recorded on a magnetic tape using the frequency band of the luminance signal.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a schematic circuit diagram showing an embodiment of the magnetic recording and reproducing apparatus of the present invention, and a diagram showing the frequency spectrum of each part for explaining the recording method, respectively.

In FIG. 1, a magnetic recording and reproducing apparatus 1 employs a heterodyne audio frequency modulation method that performs modulation and demodulation at a frequency that is sufficiently higher than the frequency of the frequency modulated audio signal actually recorded on the DI tape 2.

For this reason, a signal processing process such as frequency conversion of audio signals, which is not found in conventional high-fidelity magnetic recording and reproducing devices, is employed. In other words, the audio carrier wave used for frequency modulation of one voice signal is 1. A high frequency of about 5 Mllz higher than the carrier frequency of the luminance signal is used, and the frequency modulated audio signals of the left and right channels are added together, frequency converted, and recorded with a low frequency wave.At the time of playback, the audio read from the magnetic tape 2 is recorded. After converting the signal to a high frequency band, one individual signal is converted into a band F wave and demodulated.

First, regarding the recording system, the left and right audio signals, which have been subjected to processing such as high-frequency emphasis and excessive input restriction, are processed by frequency modulation circuits 41 and 4r at a frequency f', respectively.
L (key 5.1 MHz) and fk (mid 5.4 MHz)
The audio carrier waves are frequency-modulated and immediately added in the adder 5, resulting in a signal SA having the frequency components shown in FIG. 2 (5).
α is supplied to the frequency converters 5a and 5b. The frequency converters 6a and 5b have oscillation frequencies f and 1, respectively.
8 different oscillators 7a.

Frequency conversion is performed by the pilot signal supplied from 7b. Between the frequency f, and 18, -f, -fB =
A relationship of 150 klTz is maintained, and this relationship can be realized with extremely high accuracy by using a crystal oscillator or the like.

The frequency is converted by frequency converters 6a and 6b.

The left and right channel audio signals Se and So having the frequency components shown in FIG.
a.

8b, the frequency components shown in FIG.
The L person signal SD of P) and the frequency components shown in FIG.
= f'L - f8) and f1r3 (= f;,, -18)
The signal is sent to the door as signal S8. However, the subscript A of f is 1
The subscript B corresponds to the rotating magnetic head 9a, and the subscript B corresponds to the one-turn magnetic head 9b. *T/A character is on the left channel.

The subscript R corresponds to the right channel. In this way, the audio signal that has been designated as Igo and conforms to the β hi-fi standard is generated by the amplifier circuit IQa, 10k) + the adder 11L for adding the video signal.
#11b, recording amplifier circuit 12a;

The signals are supplied to the rotating magnetic heads 9a and 9b via the magnetic tape 12b, respectively, and recorded on the magnetic tape 2.

Note that a video input circuit 3v is connected to the adders 11a and llb via a changeover switch 13, which will be described later, and supplies a modulated luminance signal Y and a low-frequency converted chromaticity signal C for one cycle during recording. will be carried out.

Next, regarding the reproduction system, there is a one-rotation magnetic head 9a.

The audio signal read from the magnetic tape 2 by 9b is
After being amplified by the regenerative amplifier circuits 14a and 14b, the signals SD whose frequency components are fLk and Yae, and the signals whose frequency components are fLB and 'nB are output by the band-to-wave circuits 15a and 15b, respectively.
The signal S8 is converted into a P wave. continue.

A frequency converter 16a is supplied with pilot signals of frequencies f, , f8 from oscillators 7h and 7b, respectively.

16b, and the amplifier circuit 18a via changeover switches 17a and 17b, which will be described later.

18b. The audio signal that has passed through the amplifier circuits 18a and 18b is converted into F-waves by the band p-wave circuits 19, 20, 21 and 22, which have the same frequency components as the frequency modulated audio signal during recording, that is, f; and fk. The signals are supplied to the audio output circuit 24 for each left and right channel via switches 231.23r which are switched by a HERAD switching pulse. The audio output circuit 24 demodulates the frequency modulated audio signals SH and S1 of the left and right channels having the frequency components shown in FIG. do.

In this way, recording and reproduction using the heterogain audio frequency modulation method is performed by the low-frequency door plate circuit 8a of the recording system.

8b and playback band Toba circuit 19, 20, 21゜22
Since the p-wavy nature of Since this does not occur, there are advantages such as the ability to effectively suppress the occurrence of switching noise at the joints between tracks.

Here, another feature of the magnetic recording/playback device 1 is described.

We will explain how it is possible to record and play back higher quality sound when only audio is recorded.

As already mentioned, recording audio signals according to the β Hi-Fi standard records the 1-frequency modulated audio signals SD, S in the frequency band intermediate between the 1-frequency modulated luminance signal Y and the low-frequency converted chromaticity signal C. When recording only audio on magnetic tape 2 without recording video, the recording band of the luminance signal is completely white.

It can be used for recording audio signals.

That is, in the recording system, the video input circuit 3v and the adder 1
A selector switch 13 provided between 1a and 1lb selects either one of the adder 5, which performs addition of one-frequency modulation audio compensation, and the video input circuit 3v.

This is an audio recording means provided to selectively connect to the adders 11&, llb, and when video recording is not performed, the state is switched to connect the adder 5, lla, and llb. Therefore, in that case, the audio signal SA having frequency components f′T and 8 is sent to the adder 11a instead of the luminance signal.
, llb.

The information will be recorded on the magnetic tape 2 via the rotating magnetic heads 9a and 9b.

Also, in the reproduction system, a frequency converter 161! L, 16b
The changeover switches 17a and 17b provided between the amplifier circuits 18a and 18b are the reproduction amplifier circuits 14a and 14a, respectively.
14b and one of the frequency converters 16a, 16b to the amplifier circuits 18'a, 18b.
When recording is performed by switching 3 to the adder 5 side,
Reproduction amplifier circuit 14a.

14b and the amplifier circuits 18a and 18b are connected. In that case, the audio signal SA having frequency components f'L and tQ is directly supplied from the hunting tape 2 to the amplifier circuits 18a and 18b via the reproduction amplifier circuits 14a and 14b.

By the way, when the frequency-modulated audio signal SA using a high-frequency audio carrier wave is directly recorded on the magnetic tape 2 instead of the #pi degree signal, it is recorded using a shorter wavelength than the audio signal of the β-hi-fi standard. This reduces crosstalk between adjacent tracks.

Moreover, since it is closer to saturation magnetic recording than AC bias recording, the signal reproduction level is high and the single frequency transition width can be widened, resulting in flat frequency characteristics and a high SN ratio.

Furthermore, even when high-frequency recording of such audio signals is performed, when playback is performed by switching the selector switches 1711L and 17b to the frequency converters 16a and 16b, lζ
Since it is possible to reproduce audio f signals of the β Hi-Fi standard, it is possible to provide compatibility with the conventional β-hi-fi recording device.

In this way, according to the above-mentioned mother air sickle image device 1, the modulation/demodulation operation is performed at a frequency sufficiently higher than the frequency of the frequency & tone audio signal recorded on the magnetic tape 2.

Since the so-called heterodyne audio frequency modulation method is adopted, the low-frequency wave circuits 3a and 8b used during recording can be simplified, and the recording system has excellent amplitude and phase characteristics. When the luminance signal is not recorded, the outputs of the frequency modulation circuits 4g and 4r can be recorded on the magnetic tape 2 using the frequency band of the luminance signal.

Even when compared with a frequency modulated audio signal recorded between a luminance signal and a chromaticity signal, there is less crosstalk between adjacent tracks since recording is based on a shorter wavelength l.

Moreover, since it is closer to saturation magnetic recording than AC bias recording, the signal reproduction level is high and the single frequency transition width can be widened, so that flat frequency characteristics and a high SN ratio can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, the so-called heterodyne audio frequency modulation method is adopted, which performs modulation and demodulation at a frequency sufficiently higher than the frequency of the frequency modulated audio signal recorded on the magnetic tape. The low-frequency p-wave circuit used during recording can be simplified,
Note: The amplitude and phase characteristics of the 4th system are excellent, and in addition, when the luminance signal is not recorded, the output of the 1-frequency modulation circuit can be recorded on the magnetic tape using the frequency band of the luminance signal. Compared to a frequency modulated audio signal recorded between a luminance signal and a chromaticity signal, there is less crosstalk between adjacent tracks due to the shorter wavelength recording (
However, since it is closer to saturation magnetic recording than AC bias recording, the signal reproduction level is high and the one-frequency transition width can be widened, resulting in excellent effects such as flat frequency characteristics and a high SN ratio.

[Brief explanation of drawings]

1 and 2 are schematic circuit diagrams 4 and 4 showing an embodiment of the magnetic recording and reproducing apparatus of the present invention, and diagrams showing frequency spectra of various parts for explaining the recording method, respectively. 1... Magnetic recording and reproducing device, 2... Magnetic tape, 3
s...Audio input circuit-3v...Video input circuit, 4)
, 4r...frequency modulation circuit, 6L, 6b... frequency converter. 8a, 8b...low frequency p-wave circuit, 9a, 9b...rotating magnetic head, 13...changeover switch. Figure 2 Procedural amendment (method) 1. Indication of case 1982 Patent Application No. 87289 2
, Name of the invention Magnetic 4-picture playback device 3, Relationship with the case of the person making the amendment Patent applicant address (residence) 1-8 Umeda, Kita-ku, Osaka-shi, Osaka 530
No. 17 Name (Name) (193) Nippon Shinki Home Electronics Co., Ltd. Representative Takashi Murakami - 4, Agent Address (Residence) 1-9-1 Omori Higashi, Ota-ku, Tokyo 143
No. 7 No. 5, date of amendment order September 24, 1985 (
Shipping date) 6. Subject of amendment Clarification 7, Contents of amendment (1) The specification is amended as shown in the attached sheet.

Claims (1)

[Claims] A magnetic recording system that uses a predetermined frequency band between the frequency-modulated luminance signal and the low-frequency converted chromaticity signal to multiplex the frequency-modulated audio signal, and records the multiplexed signal on a magnetic tape. The playback device includes a frequency modulation circuit that modulates the frequency of the audio signal using an audio carrier wave with a frequency higher than the predetermined frequency band, and a frequency modulation circuit that modulates the frequency of the audio signal by using the audio carrier wave with a frequency higher than the audio carrier wave. a frequency converter that converts the frequency using a pilot signal whose frequency is set to be low and whose frequency is set higher than the audio frequency modulation signal in the predetermined frequency band recorded on the magnetic tape; a low-pass filtering circuit that performs low-pass filtering to extract an audio frequency modulation signal component to be recorded on the magnetic tape from the audio signal; and an output of the frequency modulation circuit when a luminance signal is not recorded on the magnetic tape; A magnetic recording and reproducing device is provided with an audio recording means for recording on a magnetic tape using the frequency band of a luminance signal.