JPS6034109Y2 - Automatic stop control circuit for tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic stop control circuit that automatically switches a tape recorder to a stop mode when the tape stops running.

Conventionally, a monitoring operation is started by the input of a clock pulse generated as the tape runs, and it is detected that the clock pulse is no longer input when the tape is wound to the tape end and the tape stops running. There were devices that automatically switched the tape recorder to stop mode.

However, in the conventional circuit described above, for example, if the cassette tape is inserted into the wrong surface and running starts from the end of the tape, the tape does not run at all and no clock pulses are generated.

Therefore, the circuit that automatically switches the tape recorder to stop mode cannot enter into monitoring operation, and the tape recorder remains in running mode.

That is, since the rotation system such as the take-up reel is locked while the motor is energized, there is a drawback that the motor may burn out or the tape may be cut.

In order to prevent the above-mentioned problems such as motor burnout and tape cutting, the present invention uses a pulse generation circuit to extract pulses synchronized with the leading edges of the tape recorder's recording/playback, fast forward, and rewind mode signals. A first one-shot circuit of the retrigger type is triggered by the extracted pulse and a clock pulse generated as the tape runs, and a second one-shot circuit is triggered by the trailing edge of the output of the first one-shot circuit. The shot circuit is triggered to send out a tape recorder stop control signal.

Hereinafter, details of the present invention will be explained using embodiments shown in the drawings.

FIG. 1 shows a block diagram showing one embodiment of an automatic stop control circuit for a tape recorder according to the present invention. CLK is a clock pulse generated as the tape runs, and is linked to the rotating system of the tape recorder, for example. It is obtained by detecting a permanent magnet provided at the periphery of a disc using a magneto-electric conversion element, amplifying the amplitude, and then shaping the waveform.

PLAY-REC, FF, and REW are mode signals that are sent out when the tape recorder is set to the recording/playback, fast forward, and rewind modes, respectively, and the OR circuit OR
The engineering will require three people to generate these three mode signals.

The output of this OR circuit OR□ is input to a pulse generation circuit PC consisting of a differentiator circuit including a capacitor C3 and a resistor R3.

This pulse generating circuit PC is connected to the OR circuit OR1.
Differentiates the output of , and generates a positive differential pulse synchronized with the rising edge of the output.

OR2 is a second OR circuit, and the clock pulse CLK
The pulses from the pulse generation circuit PG and the pulse generation circuit PG are generated by two people.

The output of this OR circuit OR2 is input to a re-trigger type first one-shot circuit 1, which is triggered at the rising edge of the first one-shot circuit 1.

The output of the first one-shot circuit 1 is input to the second one-shot circuit, which is triggered at its falling edge or trailing edge.

The output of the second one-shot circuit is sent as a stop control signal to switch the tape recorder from running mode to stop mode.

Note that C□, R1 and C2, R2 are time constant circuits for determining the first and second one-shot times T1°T2, respectively.

Further, the output of the first OR circuit OR□ is also supplied to the reset terminals R of the first and second one-shot circuits, and the reset state is canceled by the rIJ output.

Next, the operation of the automatic stop control circuit configured as described above will be explained using the second example.

i If there is tape left on the supply reel and you set the tape recorder to running mode, e.g. fast forward mode,
As shown in FIG. 2A, the first one-shot circuit is triggered at the rising edge, and then triggered one after another by the clock pulse CLK shown in FIG.

After the tape is wound to the end and the re-triggering by the clock pulse CLK is completed, the T
□When the time (for example, 3 to 4 seconds) has elapsed, the output falls, and as shown in FIG. 2, the second one-shot circuit 2 is triggered and a stop control signal for time T2 is output.

ii If there is no tape left on the supply reel, first
The first one-shot circuit 1 is activated at the rising edge of the fast-forward mode signal.
is triggered.

However, since the tape is not running, no clock pulse CLK is generated and the first one-shot circuit 1 is not retriggered.

Therefore, as shown in Figure 2, the output falls T1 hours after it is first triggered, triggers the second one-shot circuit 2, and sends out a stop control signal as shown in Figure 2, Figure 2. do.

As described above, even if the tape recorder is mistakenly run from the end, the tape recorder can be reliably switched to the stop mode, thereby preventing troubles such as motor burnout and tape cutting.

Furthermore, compared to mechanical means that detect the end of a tape by monitoring tape tension, the tape recorder can be made smaller and lighter, and there is no need for adjustment work.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of an automatic stop control circuit for a tape recorder according to the present invention, and FIG. 2 is a timing chart thereof. OR□, OR2...OR circuit, PG...
・Pulse generation circuit, 1...One-shot circuit (
Re-trigger type), 2...One-shot circuit.

Claims (1)

[Scope of utility model registration request] It is triggered by a pulse generation circuit that extracts pulses synchronized with the leading edges of the tape recorder's recording/playback, fast forward, and rewind mode signals, and by this pulse and the clock pulses generated as the tape runs. A tape recorder comprising a re-trigger type first one-shot circuit and a second one-shot circuit that is triggered by the trailing edge of the output of the first one-shot circuit and sends out a tape recorder stop control signal. Automatic stop control circuit.