JPS624944Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a display of muting of the output of the reproduced audio analog signal in an apparatus for recording and reproducing the converted audio analog signal into a PCM signal.

FIG. 1 schematically shows a signal recording and reproducing apparatus for recording and reproducing PCM signals using a VTR as an example. In FIG. 1, 1 is a low-pass filter, 2 is a sample and hold circuit, 3 is an A-D converter, 4 is a memory circuit, 5 is a waveform generation circuit, 6 is a synchronous separation circuit, 7 is a memory circuit, and 8 is a D- A converter, 9 a low-pass filter, 10 a muting circuit, 11 a muting signal generation circuit, 1
2 is a two-head helical scan type VTR, 12
a is its input terminal, 12b is its output terminal, A is its audio analog signal input terminal, and B
is the same output terminal.

That is, in this device, an audio analog signal applied to input terminal A is band-limited by low-pass filter 1, sampled by sample-hold circuit 2, and converted into a digital signal by AD converter 3. Further, in the memory circuit 4, the continuously generated digital signal is time-base compressed into PCM data with missing periods. The PCM data is converted into a recording signal by adding a synchronization signal in the waveform generation circuit 5. This recording signal is supplied to the input terminal 12a of the two-head helical scan type VTR 12 and recorded. On the other hand, during playback, the playback output is VTR
The PCM data is output to the output terminal 12b of 12, and the PCM data is separated from the synchronization signal by a synchronization separation circuit. P.C.M.
The data is input to the memory circuit 7, and the time axis is expanded in the opposite direction to that during recording, and time axis fluctuations such as jitter are removed, making it a continuous signal with no missing periods. convert it into a signal,
Muting circuit 1 via low pass filter 9
It is input to 0. The muting circuit 10 is configured to output or prohibit the audio analog signal output from the low-pass filter 9 to the output terminal B of the device, depending on the muting signal generated by the muting signal generating circuit 11. In such a PCM signal recording/playback device, the servo system may malfunction, for example, when the circuit system malfunctions when the power is turned on or off, when a blank tape is played back, or when the VTR operation mode is changed. During an unstable period or when a large number of signal errors occur due to dropouts due to tape defects, the reproduced audio analog signal becomes abnormal and abnormal noise occurs in the reproduced sound. The muting signal generation circuit 11 detects such an abnormal case and
0 is operated to prevent abnormal reproduction signals from being output.

However, when the audio signal is not output, there are cases where there is an abnormal state as described above and the muting circuit is operating, or there is a case where a silent state is recorded and reproduced. In the latter case, no audio signal is output even though the device is operating normally. Therefore, if an audio signal is not output, it is necessary to determine whether the device is in an abnormal state or is operating normally.

This idea was made in view of the above points,
By detecting an abnormality in the audio analog signal reproduced during playback and activating a muting circuit based on the detection output, and displaying on a display device that the muting circuit is in an operating state, the reproduction output is activated by the operation of the mutating circuit. It is an object of the present invention to provide a signal recording and reproducing device that can easily distinguish between a state in which there is no recorded signal and a state in which there is no reproduced output because there is no recorded signal.

An embodiment of this invention will be described in detail below with reference to FIG. In Figure 2, 1 to 12 are the first
Since it is the same as the device described in the figure, the explanation will be omitted.
13 is a display device, which receives the output of the muting signal generation circuit 11 as an input. That is, when the muting circuit 10 operates based on the output signal of the muting signal generation circuit 11, the display device 13 displays that mutating is operating. FIG. 3 shows an example of a specific configuration of this display device 13. C is an input terminal of this display device, and the output of the muting signal generation circuit 11 is inputted thereto.
Input terminal C is connected to transistor 15 via resistor 14.
The emitter of the transistor 15 is connected to the ground. Further, the collector is connected to a power source via a resistor 16 and an LED 17. The output of the muting signal generation circuit 11 is configured to output a pulse, for example.
During the muting operation, the output pulse is in the "1" state. When such a pulse is applied to the input terminal C of the display device 13, the resistance 14
Voltage is applied to the base of transistor 15 through indicate.

In addition, in the above-mentioned embodiment, an example was explained in which an LED or a transistor was used for the display, but these may be a lamp or a relay, respectively, and the display is not limited to one using a light emitting body such as an LED or a lamp. Needless to say.

As described above, according to this invention, an abnormality in the audio analog signal reproduced during playback is detected, the detected output activates the muting circuit, and the display device displays that the muting circuit is in an operating state. I decided to do this, so
The operation of the muting circuit has the effect of easily distinguishing between a state in which there is no reproduction output and a state in which there is no recorded signal and therefore no reproduction output.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of a conventional signal recording and reproducing device, FIG. 2 is a block diagram showing an embodiment of the signal recording and reproducing device according to this invention, and FIG. 3 is a block diagram showing the display device portion in FIG. FIG. 3 is a circuit diagram showing a specific example. Note that the same reference numerals in the figures indicate the same or corresponding parts. 10... Muting circuit, 11... Muting signal generation circuit, 13... Display device.

Claims (1)

[Scope of utility model registration request] Signal recording in which an audio analog signal is A-D converted into a PCM signal, this is recorded or reproduced on a recording medium, and the reproduced PCM signal is D-A converted to obtain the original audio analog signal again. The playback device includes: an abnormality detection circuit that detects an abnormality in a reproduced audio analog signal; a muting circuit that prohibits output of the reproduced analog signal when the abnormality is detected; and a display device that displays the operation of the muting circuit. A signal recording and reproducing device characterized by comprising: