JPS63149872A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain a compact constitution in a sound processing system by sharing a filter for recording an FM sound signal recorded through a rotary head for reproducing. CONSTITUTION:A sound signal FM modulated in a frequency modulator 3 is synthesized with the FM luminance signal of a video signal in a mixing circuit 5 and recorded on a magnetic tape by the recording and reproducing head 20 of the rotary head. At the time of a reproduction, A reproduced FM sound signal separated in a separation circuit 9 by switching switches 13, 14 is supplied to a frequency demodulation circuit 10 via a BPF 4. This BPF is shared for recording and for reproducing, thereby, the number of parts is reduced to realized the compact constitution in the recording and reproducing system.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a rotary head type magnetic recording and reproducing apparatus such as a video chip recorder having a recording and reproducing function of frequency modulated audio signals.

Conventional technology In recent years, in order to make the audio recorded on magnetic tape used for video recording high-fidelity, frequency-modulated audio signals are frequency-multiplexed on the same track in a frequency band intermediate between the frequency-modulated luminance signal and the low-frequency converted chromaticity signal. Magnetic recording and reproducing devices for recording are in practical use, and an 8 mm video tape recorder is known as a good example.

FIG. 2 is a schematic block diagram showing a frequency modulated audio signal processing circuit in an 8 mm video tape recorder. In FIG. 2, 1 is an audio signal input terminal into which an audio signal is input, 2 is an audio signal processing device that compresses and expands the dynamic range of audio, and 3 is a terminal that receives audio signals from this audio signal processing device 2. This is an audio signal processing circuit that frequency-modulates a carrier wave using an audio signal as a modulation signal and outputs a frequency-modulated audio signal. The frequency modulated audio signal has a carrier frequency of 1.5 as shown by FMA in the frequency map of FIG. s
MHz, and the maximum bandwidth l latency is ±150 KHz, and is located between the frequency-modulated luminance signal and the low-frequency converted chromaticity signal. In FIG. 2, a low-pass filter (hereinafter referred to as LPF) 21 receives the frequency-modulated audio signal from the frequency modulator 3 and limits the band of the frequency-modulated audio signal so that it does not overlap with the frequency-modulated luminance signal. (omitted). 6 in Figure 2
is a mixer that adjusts the frequency modulated luminance signal from the luminance signal processing circuit system, the low-pass converted chrominance signal from the chromaticity signal processing circuit system, and the frequency modulated audio signal to a predetermined level and adds them. 6 is a recording amplifier for making the mixed output signal from this mixer the optimum recording current.

7 is a rotary transformer for recording the amplified mixed output signal from this recording amplifier onto a magnetic recording medium.

Further, 20 is a magnetic head, and 7 and 2Q are attached to the drum. The frequency allocation of the frequency-converted luminance signal, low-frequency converted chromaticity signal, and frequency-modulated audio signal is determined by adjusting the horizontal resolution, S/N ratio, etc. according to the frequency characteristics of the magnetic head and magnetic recording medium used. This will be determined after consideration. In addition, in frequency modulation, all the energy of the transmitted signal is in the sidebands, so if you attenuate them with a filter, the horizontal resolution will drop. Therefore, the frequency of the low-pass converted chromaticity signal is 9
The carrier frequency and frequency shift of the frequency modulated sound signal are also selected so as not to overlap the band of the frequency modulated luminance signal as much as possible.

The above is the recording system signal processing.

On the other hand, during reproduction, a frequency modulated luminance signal is generated by 20 magnetic heads and 7 rotary transformers.

A mixed signal of the low-pass converted chrominance signal and the frequency modulated audio signal is recovered and sent to a preamplifier at 8. This preamplifier amplifies the signal to a level that is sufficient to drive subsequent circuits, and also improves high frequency characteristics.

The amplified mixed signal is then separated into a frequency modulated luminance signal, a low frequency converted chromaticity signal, and a frequency modulated audio signal in a separation circuit 9. Further, the frequency modulated audio signal is subjected to band limitation by a band pass filter 22 (hereinafter abbreviated as BPF). In FIG. 2, reference numeral 10 denotes a frequency demodulator, which demodulates a band-limited frequency-modulated audio signal and converts it into an audio signal. The audio signal demodulated by this demodulation circuit 10 has its dynamic range expanded by an audio signal processing device 11 and is output to an audio output terminal 13. In the manner described above, audio signals are recorded and reproduced.

Problems to be Solved by the Invention However, in the conventional video/audio multiplex recording device configured as described above, the LPF used in the thread path during recording and the BPF used in the thread path during playback. However, since different filters are used for each, there is a problem in that separate filters and circuits are required for the recording system and the reproducing system.

Means for Solving the Problems In order to solve the above problems, the present invention provides an LPF through which the frequency-modulated audio signal passes before being mixed with the frequency-modulated luminance signal and the low-pass converted chromaticity signal in the recording system. , a BPF through which the frequency-modulated audio signal separated from the frequency-modulated luminance signal and the low-frequency conversion color signal in the reproduction system passes before undergoing frequency demodulation.
This is configured to process both by using the same band-pass filter.

Function: With the above configuration, the band-pass filter through which the frequency-modulated audio signal passes during recording and the band-pass filter through which the frequency-modulated audio signal passes during playback are the same filter, so this circuit is configured. The area of the board required for this can be reduced, and the audio processing system can be downsized. Furthermore, the number of parts can be reduced, leading to lower costs.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In FIG. 1, an audio signal input from an audio signal input terminal 1 to which an audio signal is input has its dynamic range compressed by an audio signal processing device 2. As shown in FIG. The audio signal that has passed through the audio signal processing device 2 enters a frequency modulation circuit 3 and frequency-modulates a carrier wave as a modulation signal to become a frequency-modulated audio signal. The frequency-modulated audio signal passes through a switch 13 and a band-pass filter 4 (hereinafter abbreviated as BPF 2) that limits the band of the frequency-modulated audio signal so that it does not overlap with the frequency-modulated luminance signal and the low-pass converted chromaticity signal. This frequency modulated audio signal passes through a switch 14 and is mixed with a frequency modulated luminance signal and a low frequency converted chromaticity signal in a mixer 6, and this mixed signal becomes an optimum recording current for a recording amplifier 6, and a rotary transformer 7 and The information is recorded on the magnetic recording medium by the magnetic head 20. The above is the flow of signals in the recording system.

Next, during reproduction, the reproduction signal reproduced from the magnetic recording medium by the rotor IJ-transformer 7 and the magnetic head 20 is sent to the preamplifier 8. The reproduced signal amplified by the preamplifier 8 is separated by a separation circuit 9 into a frequency modulated luminance signal, a low frequency conversion chromaticity signal, and a frequency modulated audio signal. Among these, the frequency modulated audio signal is transmitted to the switch 14.
The frequency-modulated audio signal passes through the same BPF 2 4 and switch 13 that it passed during recording, and flows to the frequency demodulator 10, where the band-limited frequency-modulated audio signal is demodulated to become an audio signal, and then sent to the audio signal processing device again. 11, it becomes an audio signal whose dynamic range has been expanded, and is outputted as audio from an audio output terminal 12.

Effects of the Invention As is clear from the above embodiments, the present invention provides a low-pass filter through which a frequency-modulated audio signal frequency-modulated during recording passes, and a low-pass filter through which a frequency-modulated audio signal separated from a mixed signal passes during playback. By processing signals using the same band-pass filter, the area of the board required to configure this circuit can be reduced, and the audio processing system can be made smaller. .

Furthermore, since the number of parts is reduced, costs can also be lowered.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts of an embodiment of the present invention, and FIG.
The figure is a block diagram showing conventional frequency modulation audio signal processing, and FIG. 3 is a diagram showing frequency allocation. 1... Audio signal input terminal power, 2... Noise removal device (recording), 3... Frequency modulator, 4...
...Band pass filter, 5...Mixer,
6... Recording amplifier, 7... Rotary transformer, 8... Preamplifier, 9...
Separator, 10... Frequency demodulator, 11...
... Noise removal device (playback), 12 ... Audio signal output terminal, 13.14.15 ... Deployment/playback changeover switch, 20 ... Recording/playback head. Name of agent: Patent attorney Toshio Nakao and one other person Satsuma

Claims (1)

[Claims] A magnetic recording and reproducing device that has a rotary head for recording video and audio signals on a rotary cylinder, and records video and audio signals on a magnetic tape using the rotary head, and frequency modulates the audio signal input during recording. The filter includes a filter through which the frequency modulated audio signal obtained by the above-described method is passed through before being recorded on the magnetic tape by the rotating head, and the frequency modulated audio signal taken out from the magnetic tape by the rotating head during playback is passed through the filter. , a magnetic recording/reproducing device characterized in that it also serves as a filter through which a signal is passed before being subjected to frequency demodulation.