JPS593384Y2 - Magnetic tape automatic stop device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic stop device for detecting a non-recording band on a magnetic tape and repeatedly reproducing one sentence.

Conventionally, this type of device detects the unrecorded zone between each sentence during rewinding during repeated playback, charges or discharges with a charging/discharging circuit, and then drives the switching element after a certain period of time has elapsed. In this method, the magnetic tape is stopped at a position with some margin from the beginning of the sentence that is to be repeatedly played back. Although it is possible to set the stopping time by adjusting the constant of the time constant element in this case, The accuracy is extremely low, and the drawback is that the stop time becomes unstable, especially due to variations in element constants and fluctuations in the power supply voltage.

Furthermore, if a short non-signal section on the recording band of the magnetic tape continues, the charging or discharging circuit will be charged or discharged each time, and the charging/discharging circuit will not be in its initial state when the non-recording band between each sentence is detected. Therefore, the variation in stop time due to this cannot be ignored.

In addition, the above-mentioned variation in stop time also has the risk of malfunctions such as stopping in the recording band due to detection of the above-mentioned no-signal portion and repeating playback from the middle of a sentence.It is necessary to prevent such malfunctions and variations in stop time. This requires highly accurate elements, making it relatively expensive.

The present invention detects a non-recording band as a switching point from a recording band to a non-recording band when rewinding a magnetic tape, and also counts the output signal of an oscillator that oscillates at a constant frequency from the time the non-recording band is detected. The numerical value obtained by the counting operation is compared with a set value arbitrarily set in advance, and when the numerical value obtained from the counting operation matches the set value or exceeds the set value, the running is stopped, so that there is no malfunction. The purpose is to provide an automatic stop device with excellent accuracy.

Embodiments of the present invention will be described in detail below based on the accompanying drawings.

In the figure, 1 is a playback head, 2 is an amplifier circuit, and 3 is a waveform shaping circuit, which shapes the waveform of the audio signal on the recording band of the magnetic tape and converts it into a DC signal at a constant voltage level.

4 is an oscillator such as an astable multivibrator that outputs a signal pulse of a constant period; 5 is a reversal signal generation circuit that outputs a pulse signal when the magnetic tape is reversed (when reversing from normal running to rewinding running); 6 is a flip-flop circuit that is reset by a pulse signal from the reversal signal generating circuit 5, and is set when the magnetic tape is reversed and the recording band is played back by the reproducing head 1; 7 is a switch A;
The ND circuit 8 indicates a NOT circuit, and the AND circuit 7 passes the output signal from the oscillator 4 at the same time as the non-recording band of the magnetic tape is detected.

9 is a counter, which is the output of the AND circuit 7, that is, the oscillator 4.
A signal corresponding to the elapsed time from the detection of the non-recording band is applied to the comparator 10.

Reference numeral 11 denotes a setting device that can arbitrarily set the time from when a blank band is detected to when the magnetic tape rewinding stop. A memory element such as an S-R flip-flop is provided corresponding to the output terminal, or it is simply connected to the power supply via an on/off switch. The signal forms are compared, and a magnetic tape running stop signal is output after the time set by the setting device 11 has elapsed.

Here, the comparator 10 inputs the corresponding outputs of the counter 9 and the setter 11 to an AND circuit, respectively, and
By further passing the output of the D circuit through a multi-input AND circuit, when all of the corresponding output states match, the match signal, that is, the stop signal is output.

In the above configuration, when a magnetic tape is reproduced, a non-recording band is detected at the end of one sentence, and the running is reversed, a pulse signal is outputted from the reversal signal generating circuit 5 and applied to the reset terminal of the flip-flop circuit 6.

Therefore, the output of the flip-flop circuit 6 maintains a low level until it is set again, and therefore the output of the AND circuit 1 also maintains a low level.

When the magnetic tape is rewound and the recording band is played back, the playback signal from the waveform shaping circuit 3 is applied to the set terminal of the flip-flop circuit 6 and then to the foot-flop AND circuit 7.

However, the output of the waveform shaping circuit 3 becomes the I level via the NOT circuit 8 and is applied to the other input of the AND circuit 7, so the output of the AND circuit 7 maintains a low level.

When the magnetic tape is further rewound and reaches a non-recording band, the reproduction signal from the waveform shaping circuit 3 disappears, and all inputs to the AND circuit 7 through the NOT circuit 8 become high level, and a constant signal is output from the oscillator 4. A periodic signal pulse is applied to the counter 9.

Here, since the reproduction signal of the recording band that is reproduced immediately after the running reversal is applied to the reset terminal of the counter 9, the counter 9 starts counting the output signal of the oscillator 4 from the time when the non-recording band is detected, A signal form corresponding to the elapsed time is applied to the comparator 10.

Further, since the stop time is arbitrarily set in the setting device 11, a signal form corresponding to the stop time is applied to the comparator 10, and the comparator 10 corresponds to the elapsed time from the counter 9. The signal form corresponding to the stop time from the setting device 11 is compared, and when the elapsed time matches the stop time or exceeds the stop time, a stop signal is output, and an electromagnetic solenoid or the like is activated to This stops tape rewinding.

As described in detail above, the present invention detects a non-recording band on a magnetic tape, counts the output signal of the oscillator 4 which always oscillates at a constant frequency from the time of detection, and compares it with the value set in advance by the setting device 11. In addition, by configuring the magnetic tape to stop running when the value obtained by the counting operation matches or exceeds the setting value of the setting device 11, it is possible to set the stop time with high precision, and the magnetic tape is Therefore, it is possible to provide a highly reliable magnetic tape automatic stopping device that is free from malfunctions and has a stable stopping position.

[Brief explanation of the drawing]

The figure is a circuit configuration diagram showing an embodiment of the present invention. Oscillator: 4, inverted signal generation circuit: 5, counter: 9, comparator: 10, setter: 11.

Claims (1)

[Scope of utility model registration request] The unrecorded zone between each sentence recorded on the magnetic tape is detected by rewinding and playing, and after a certain period of time has elapsed since this detection, rewinding is stopped and switching to playback, thereby repeatedly playing one sentence. This automatic stop device includes an inverted signal generating circuit that outputs an inverted signal when the running is reversed from playback to rewinding, an oscillator that always oscillates at a constant frequency, and a circuit that is energized by the inverted signal and starts recording. Opening/closing is controlled by a flip-flop circuit that is set during band playback, a non-recording band detection signal between each sentence detected when the magnetic tape is running, and an output signal of the flip-flop circuit, and the oscillator is activated from the time a non-recording band is detected. A switch that allows the output signal to pass through, a counter that counts the signal from this switch, a setting device that can set a signal corresponding to an arbitrary time in advance, and a value and setting based on the counting operation of the counter. An automatic magnetic tape stop device comprising a comparator that compares a value set in a counter with a set value and outputs a stop signal when the value on the counter matches or exceeds the set value.