JPS626586Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a recording device, and includes an oscillator that outputs an identification signal of a single frequency other than an audio frequency, and a detection circuit that detects the maximum change point of this identification signal and outputs a detection signal. , the amplitude of the identification signal is gradually increased from zero from the position where the detection signal is output, and after being fixed at a predetermined amplitude value for a predetermined period, the amplitude of the identification signal is gradually attenuated and the amplitude of the identification signal is gradually attenuated from the position where the detection signal is output. By providing a control circuit that makes the amplitude zero and a superimposition recording circuit that superimposes and records the signal output from this control circuit on the audio frequency signal for a predetermined period, it is possible to detect the audio frequency signal without detecting click noise. The purpose is to provide a recording device that allows good listening.

Conventionally, for example, in order to automatically control the running of a magnetic tape in a magnetic recording/reproducing device, an audible single frequency signal (an identification signal for identifying a recording position, a cue signal) outside the audible frequency band is placed at a predetermined position on the magnetic tape. The signal is recorded superimposed on a frequency signal, and upon playback, a single frequency signal is detected so that the running of the magnetic tape can be stopped, etc. this is,
As shown in Figure 1, the audio frequency signal is input to input terminal 1.
The output signal a from the signal oscillator 4 outside the audible frequency band is turned into a signal b by a switch 5 that opens and closes intermittently. The signal is supplied to the mixing circuit 3, where the audio frequency signal and the signal b, which is a single frequency signal, are superimposed and supplied to the output terminal 6.
This signal is now recorded on magnetic tape. During reproduction, a single frequency signal is detected, and the running of the magnetic tape is controlled by this detection. However, as shown in FIG.
Therefore, when the switch 5 is opened and closed, extra noise is generated, and this noise becomes extremely annoying when playing back magnetic tapes. In this case, its value decreases significantly.

Therefore, in order to solve the above drawbacks, the inventor of the present invention
He developed a recording device as shown in FIGS. 3 and 4. In the figure, 10 is an input terminal to which an audio frequency signal is supplied, and this audio frequency signal is supplied to a mixing circuit 12 via an amplifier circuit 11. On the other hand, a single frequency signal c outside the audio frequency band is supplied to a switching circuit 14 by a single frequency signal oscillator 13, and a rectangular wave generator 15 supplies a predetermined rectangular wave d to an integrator circuit 16. The wave d is converted into a substantially rectangular wave e with a gentle rising and falling waveform, and this substantially rectangular wave e
The single frequency signal c is also supplied to the switching circuit 14, and the single frequency signal c is converted into an intermittent single frequency signal. Then, this single frequency signal and the audio frequency signal are superimposed and recorded on the magnetic tape from the output terminal 17.

To explain these integrating circuits and switching circuits in more detail, as shown in FIG.
The base of the transistor 20 is connected to the integrating circuit, and the emitter of the transistor 20 is connected to the photocoupler 21. The primary side cathode of the photocoupler 21 is grounded via a resistor 22, and the secondary side of the photocoupler 21 is connected to the single frequency signal oscillator 13 and the mixing circuit 12. be done. Note that 23 is a power supply terminal.

Then, when the rectangular wave d is supplied to the integrating circuit,
This rectangular wave d becomes a substantially rectangular wave e with gentle rises and falls, and this substantially rectangular wave is supplied to the base of the transistor 20, and as the collector current of the transistor increases, the secondary side of the photocoupler 21 As the resistance value of the photocoupler decreases, a single frequency signal begins to appear in the mixing circuit gently from zero level, then becomes a signal at the same level as the single frequency signal, and the collector current of the transistor begins to decrease, the secondary side of the photocoupler The resistance value of increases, the signal supplied to the mixing circuit gradually attenuates,
The single frequency signal of FIG. 5c becomes an intermittent single frequency signal of FIG. 5f.

The single frequency signal in Figure 5 f is obtained by converting the rectangular wave into a substantially rectangular wave with gentle rise and fall using an integrating circuit, and using this substantially rectangular wave to obtain the single frequency signal c. Therefore, there is no click noise like in the past, so even if such a single frequency signal is recorded on a magnetic tape and this signal is used to stop the magnetic tape during playback, there will be no unpleasant noise. The effect is remarkable in broadcasting stations that require high accuracy.

However, it gradually became clear that even the developed recording device was not satisfactory.

As a result of further research into the cause of this drawback, the present inventor found that this drawback is due to the fact that the temporal position of the recording start of the single frequency signal is not the zero crossing point of the single frequency signal, which causes noise during switching. They discovered that this occurs, and based on this knowledge, they came up with the present invention.

FIG. 6 is a partial block diagram of the first embodiment of the recording apparatus according to the present invention. In the figure, 30 is an input terminal to which an audio frequency signal is supplied, and this audio frequency signal is supplied to a mixing circuit 32 via an amplifier circuit 31. On the other hand, a single frequency signal g outside the audio frequency band is directly supplied to a switching circuit 34 similar to that shown in FIG. This amplifier circuit converts the sine wave of the single frequency signal g into a rectangular wave h,
This rectangular wave h is supplied to a differentiating circuit 36, which converts the rectangular wave h into a pulse i having a signal only at the zero cross point of the single frequency signal g,
Circuit 3 where this pulse i responds only to the positive pulse
7 becomes a pulse j, and this pulse j is supplied to a phase shifting circuit, for example, a flip-flop circuit 38. Further, a predetermined rectangular wave k is supplied from the rectangular wave generator 39 to a flip-flop circuit 38, and by this flip-flop circuit, the rectangular wave k becomes a rectangular wave l that rises at the zero cross point of the single frequency signal, and this rectangular wave l is The signal is supplied to an integrating circuit 40 similar to that shown in FIG. The amplitude value is gradually increased from the change point, fixed at a predetermined amplitude value for a predetermined period, and then gradually decreased to produce a single frequency signal g.
A single frequency signal n outside the audible frequency band for identification, whose amplitude is zero at the maximum change point of , is obtained. Then, this single frequency signal n and the audio frequency signal are superimposed and recorded on the magnetic tape from the output terminal 41.

To describe the amplifier circuit and the like in this embodiment in more detail, as shown in FIG. , the circuit that responds only to positive pulses consists of a resistor 49 and a transistor 50, and the flip-flop circuit consists of an inverter gate 51 and a JK flip-flop 52. In addition, 53
is the power supply terminal.

In this embodiment, since the rising edge of the substantially rectangular wave m corresponds to the zero-crossing point of the single frequency signal g, a click occurs when converting the single frequency signal g into an intermittent single frequency signal n. This has the great advantage that noise is less generated than in the case of the recording apparatus shown in FIG.

FIG. 9 is a partial block diagram illustrating a second embodiment of the recording apparatus according to the present invention. This embodiment is almost the same as the first embodiment, but whereas in the first embodiment only positive pulses are used among the pulses having a signal only at the zero-crossing point of a single frequency signal, in this embodiment In the example, negative pulses were also used. That is, 60 is an input terminal to which an audio frequency signal is supplied, and this audio frequency signal is supplied to a mixing circuit 62 via an amplifier circuit 61. On the other hand, a single frequency signal o is generated by a single frequency signal oscillator 63 outside the audio frequency band to a switching circuit 64 similar to the first embodiment.
and this single frequency signal o
is also supplied to an amplifier circuit 65, which converts the sine wave of the single frequency signal o into a rectangular wave p, and this rectangular wave p is supplied to a differentiating circuit 66,
Through a differentiating circuit, the rectangular wave p becomes a pulse q having a signal only at the zero cross point of the single frequency signal o, and this pulse q is divided into a circuit 67 that responds only to positive pulses and a circuit 67' that responds only to negative pulses and inverts it. The pulse r is supplied to the OR circuit 68 via the 1st embodiment and is converted into a pulse r, and this pulse r is supplied to a circuit for shifting the phase, for example, a flip-flop circuit 69, in the same manner as in the first embodiment. Further, a predetermined rectangular wave s is supplied from the rectangular wave generator 70 to a flip-flop circuit 69, and the flip-flop circuit converts the rectangular wave s into a rectangular wave t that rises at the zero cross point of the single frequency signal o. t is supplied to an integrating circuit 71 similar to that of the first embodiment, and becomes a substantially rectangular wave u having a gentle rising and falling waveform, and this substantially rectangular wave u is supplied to a switching circuit 64. A single frequency signal v similar to that obtained is obtained. Then, this single frequency signal v and the audio frequency signal are superimposed, and the output terminal 7
Since 2, it has been recorded on magnetic tape.

To explain the OR circuit in this embodiment more specifically, the OR circuit consists of a NAND gate 73, and the circuit that inverts in response to only negative pulses includes transistors 74, 75 and resistors 76, 7.
Consisting of 7, 78, and 79. Note that 80 and 81 are power supply terminals.

Similar to the first embodiment, this embodiment has smaller click noise than the recording apparatus shown in FIG.
Furthermore, since a negative pulse is also used compared to the first embodiment, when a single frequency signal is superimposed on a predetermined position of an audio frequency signal, the position closer to the desired position, that is, the maximum deviation is the single frequency signal. can be superimposed at a desired position by the length of a half wavelength.

Note that the upper and lower limits of the audio frequency signal may be limited through a high-frequency cutoff or low-frequency cutoff filter. However, it also includes frequency ranges outside the above limits.

As described above, the recording device according to the present invention includes an oscillator that outputs an identification signal of a single frequency other than an audio frequency, a detection circuit that detects the maximum change point of this identification signal and outputs a detection signal, and a detection circuit that outputs a detection signal by detecting the maximum change point of this identification signal. The amplitude of the identification signal is gradually increased from zero from a position where the signal is output, and after being fixed at a predetermined amplitude value for a predetermined period, the amplitude of the identification signal is gradually attenuated and the amplitude is brought to zero at a position where the detection signal is output. The present invention is equipped with a control circuit for recording a signal output from the control circuit and a superimposition recording circuit for superimposing and recording a signal output from the control circuit on an audio frequency signal for a predetermined period of time. When detecting frequency signals and automatically controlling the running of the recording medium, there is almost no click noise, so the audio frequency signal can be heard clearly, and it is about the same size and size as conventional recording devices. It has the advantage of being inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a partial block diagram of a conventional recording device, FIG. 2 is a diagram for explaining the operation of the recording device shown in FIG. 1, and FIGS. 3 and 4 are partial block diagrams of the recording device. , FIG. 5 is a diagram for explaining the operation of the recording apparatus shown in FIG. 3, FIG. 6 is a block system diagram of the first embodiment of the recording apparatus according to the present invention, and FIG.
A diagram showing an example of a specific circuit of the recording device shown in the figure, FIG. 8 is a diagram for explaining the operation of the recording device shown in FIGS. 6 and 7, and FIG. 9 is a diagram according to the present invention. Block system diagram of the second embodiment of the recording device, first
0 and 9, and FIG. 11 is a diagram for explaining the operation of the recording apparatus shown in FIGS. 9 and 10. 30,60...Input terminal, 31,61...Amplifying circuit, 32,62...Mixing circuit, 33,63...
Single frequency signal oscillator, 34, 64...Switching circuit, 35, 65...Amplification circuit, 36, 66
...differentiation circuit, 37, 67...circuit that responds only to positive pulses, 67'...circuit that responds only to minus pulses, 38,69...flip-flop circuit, 40,71...integrator circuit.

Claims (1)

[Claims for Utility Model Registration] An oscillator that outputs an identification signal with a single frequency other than an audio frequency; a detection circuit that detects the maximum change point of this identification signal and outputs a detection signal; A control circuit that gradually increases the amplitude of the identification signal from zero from a position where the detection signal is output, fixes it at a predetermined amplitude value for a predetermined period, and then gradually attenuates the amplitude of the identification signal and makes the amplitude zero at a position where the detection signal is output. and a superimposition recording circuit that superimposes and records the signal output from the control circuit on an audio frequency signal for a predetermined period of time.