JPS6331067A - Sound recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent an allophone occurring at a recording starting point by muting the output of a recording circuit for a constant time from the recording starting point of a sound signal at the time of recording. CONSTITUTION:Muting circuits 5 and 9 mute a recording signal for a constant time determined beforehand by a timer 12, non-modulates an FM sound input and records the data of (00...00) at a PCM sound input. A constant time T determined by the timer 12 is determined in a reproducing system by the time necessary to determine the decision whether or not the PCM recording is executed. When the muting circuit 5 is operated, the sound signal inputted from a terminal 3 is made into the non-modulation, and when the muting circuit 9 is operated, the data of (00...00) are recorded at the sound signal inputted from a terminal 7 and both FM sound input and the PCM sound input are silence- recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a device that can process audio signals using two types of modulation methods, for example,
Used for millimeter VTR.

(Prior Art) Conventionally, in an 8 mm VTR, audio signals can be modulated in two types: FM and PCM. And this kind of 8mm VTR
A playback mode has been added that gives priority to playing back PCM sound over FM sound. During playback, it is determined whether or not PCM sound is recorded, and the FMiii circuit or PCM demodulation circuit is switched to reproduce the playback sound signal. was being output.

(Problem to be Solved by the Invention) However, in such an 8mm VTR, FM audio is output at the recording start point until it is determined whether PCM audio is being recorded. There was a problem in that when different sounds were recorded for PCM and PCM, an abnormal sound could be heard.

(Means for Solving the Problems) The present invention provides an audio recording and reproducing apparatus equipped with a recording circuit and a reproducing circuit capable of processing audio signals using two types of modulation methods. The output of the recording circuit is muted for a certain period of time. The two types of modulation methods for 8mm VTRs are FM and PCM.

(Function) Both FM recording and PCM recording are muted for a certain period of time from the recording start point to record no signal. During playback, neither audio is output until the recording modulation method is determined.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a recording system in an audio recording/reproducing apparatus according to the present invention. This example shows a recording circuit of an 8mm IJVTR, and the output of the audio recording circuit A and the video signal are connected to the recording amplifier 1. The signal is amplified and supplied to the recording head 2, where it is superimposed and recorded on a video tape (not shown).

In FIG. 1, a terminal 3 is a terminal to which an audio signal to be FM modulated is input, and the audio signal input from this terminal 3 is amplified by a puffer amplifier 4, and then passed through a muting circuit 5 to an FM modulation circuit 6. has been entered. Also,
Terminal 7 is a terminal to which an audio signal to be PCM modulated is input, and the audio signal input at terminal 7 is input to PCM signal processing circuit 10 via puffer amplifier 8 and muting circuit 9. Said muting circuit 5゜9
The recording signal is muted for a predetermined period of time by the timer 12, the FM audio input is unmodulated, and the P
This is a circuit for recording data (00...00) in the CM audio input. The fixed time T determined by the timer 12 is determined to be the time (for example, 1 second) necessary for a reproduction system (not shown) to determine whether PCM recording is being performed. Control circuit 11
1 is a circuit that detects a recording start point by operating a recording switch (not shown), etc. When the recording start point is detected by this control circuit 11, a detection signal activates a timer 12, and a certain period of time T (in this example (1 second) Activate the muting circuit 5.9. When the muting circuit 5 is activated, the audio signal input from the terminal 3 is unmodulated, and when the muting circuit 9 is activated, data (00...00) is recorded in the audio signal input from the terminal 7. Both the FM audio input and the PCM audio input are recorded without a signal.

Figure 2 is a waveform diagram illustrating the state of input signals recorded by FM and PCM.
In the same figure (bl shows the input signal to the FM modulation circuit 6. In the figure (bl), the muting operation is performed in the muting circuit 5 during a period T during which a constant level is maintained from the recording start point 13. This period is F.
The M input signal is in an unmodulated state, that is, in a silent state. The reproduced signal obtained by reproducing the signal in Figure 2 (the same figure) also has the same waveform as Figure 2 (bl). Figure 2 (C1, (dl
shows the processing of the PCM input signal, and (000...00) is recorded for the period T in FIG. 4(d).

However, when the PCM priority mode is set during playback, the period T
During this period, both FM and PCM are silent, so even if the FM signal is output until the PCM recording decision is made, no abnormal noise will be generated from the audio output. In the above-described embodiment, a case where processing can be performed using two types of modulation methods, FM and PCM, has been described, but the present invention is not limited to this, and the present invention can also be applied to cases where other modulation methods are adopted.

(Effects of the Invention) As described above, according to the present invention, abnormal noise occurring at the recording start point can be prevented in an apparatus capable of processing using two types of modulation methods.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the audio recording and reproducing apparatus according to the present invention, and FIG. 2 (al, (bl) is a waveform diagram explaining the processing of an FM input signal, FIG.
FIG. 3 is a waveform diagram illustrating processing of a CM input signal. 5.9...Muting circuit 11...Control circuit 12...Timer Figure 7 A and 2 Figures Procedure Master Author (Method) % Formula % 1. Indication of Incident Patent Application No. 1988 174440 No. 2, Name of the invention: Audio recording and reproducing device 3, Relationship with the person making the amendment Case Patent applicant address: 22-22 Nagaike-cho, Abeno-ku, Osaka City Name (
504) Sharp Corporation Representative Haruo Tsuji 4, Agent 530 Telephone (06) 364-8253 Address 4-4-18 Nishitenma, Kita-ku, Osaka 1982
September 3, 2017 (Shipping date: September 30, 2016) 6. Subject of amendment 7. Contents of amendment (11 "Block diagram" and "Figure 2 (a)" on page 6, line 6 of the specification) Add the following sentence between: "Figure 2 is a waveform diagram illustrating the state of input signals recorded by FM and PCM," (2) Figure 2 in the drawings:
Amend as shown in the attached drawing. that's all

Claims (1)

[Claims] 1) A recording circuit capable of processing audio signals using two types of modulation methods;
An audio recording and reproducing device comprising a reproducing circuit, characterized in that, during recording, the output of the recording circuit is muted for a certain period of time from the recording start point of an audio signal.