JPS6312417Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply voltage check circuit suitable for tape recorders, particularly portable tape recorders that use batteries as a power source.

Generally, tape recorders that use batteries as a power source are equipped with a power supply voltage check circuit that indicates whether the voltage of the battery being used is within the voltage required for normal operation of the tape recorder. Such conventional check circuits generally provide instructions by turning on or off a light emitting diode during a recording operation. However, with such a circuit, the user often overlooks the instructions, and the recording operation continues without replacing the battery, which becomes an extremely serious problem when important information is being recorded. .

The present invention has been developed in view of these points, and will be described in detail below with reference to the drawings. The illustrated circuit is an embodiment of the power supply voltage check circuit of the present invention. In the figure, 1 is a battery as a power source, and 2 and 3 are between a power line 4 to which current is supplied from the battery 1 and the ground. The bleeder-connected bias resistor 5 is a detection transistor whose emitter is grounded and whose collector is connected to the power supply line 4 via a light emitting diode 6 and a resistor 7, and whose base is connected to the bias resistors 2 and 3. Connected to common connection point A. The resistance values of the bias resistors 2 and 3 are such that when the voltage of the power supply line 4 becomes lower than the voltage value necessary for normal operation of the tape recorder due to the battery 1 being exhausted, the detection transistor 5 is activated.
is set to a value that makes it non-conductive. Reference numeral 8 indicates the light emitting diode 6 by means of a rotary plate having a through hole which rotates as the reel shaft (not shown) rotates.
The control electrode is intermittently irradiated with light from the phototransistor, and the emitter is grounded and the collector is connected to the power supply line 4 via a resistor 9. The phototransistor 8 repeats a conductive state and a non-conductive state while the reel shaft is rotating, and becomes a conductive state or a non-conductive state when the reel shaft stops rotating due to the end of the tape. 10 is an end detection circuit that detects the end of the tape based on a signal obtained from the collector of the phototransistor 8; 11 is an oscillator that oscillates when a signal associated with end detection is output from the end detection circuit 10; It is a circuit. Reference numeral 12 denotes an input terminal 1 to which a signal reproduced by a magnetic head (not shown) is applied during reproduction operation.
3 is a preamplifier circuit, 14 is a recording/playback switch, the playback terminal 14P of which is connected to the output terminal of the preamplifier circuit 12, and the recording side terminal 14R connected to the output terminal of the oscillation circuit 11. It is connected to the. A main amplifier circuit 15 is supplied with power from the power line 4 and is connected to a speaker 16 as a load, and its input terminal is connected to the common terminal 14O of the recording/playback switch 14. 17 is a motor that drives the magnetic tape; 18 is a speed control circuit that drives the motor 17 and controls its rotational speed; when a signal associated with end detection is applied from the end detection circuit 10, the motor 17 It is configured to stop the rotation of.

The present invention is constructed as described above, and its operation will be explained next. A case will be described in which the voltage of the battery 1 is sufficiently high to perform a recording operation. When a recording operation is performed, the recording/reproduction changeover switch 14 is switched to the state shown in the figure, and power is supplied to each circuit, so that the tape recorder enters a recording operation state. In such a recording operation state, the detection transistor 5 is in a conductive state and the light emitting diode 6 is lit.
When the tape is running, light from the light emitting diode 6 is intermittently irradiated onto the phototransistor 8 as the reel shaft rotates, so the phototransistor 8 repeats a conductive and non-conductive state. Become. Therefore, the termination detection circuit 1
No signal is output from 0, and the oscillation circuit 1
1 is in a non-operating state, and the speed control circuit 18 is in a state of driving the electric motor 17 at a constant speed. When the tape reaches its end during such a recording operation, the reel shaft stops rotating, so the phototransistor 8 remains in a conductive state or a non-conductive state. As a result, the termination detection circuit 10 is activated, and a signal is outputted from its output terminal and applied to the oscillation circuit 11 and the speed control circuit 18. Therefore, the oscillation circuit 11 operates in oscillation, and its oscillation output is input to the main amplifier circuit 15 via the recording/playback switch 14, where it is amplified and then emitted from the speaker 16. Furthermore, as a result of the signal from the termination detection circuit 10 being applied to the speed control circuit 18, the speed control circuit 18 becomes inactive and the motor 17 stops rotating. Through the above operations, the user can recognize that the tape has ended.

As described above, the tape end detection operation is carried out in the recording operation state. Next, a case will be described in which the battery 1 is exhausted and the voltage drops to such an extent that the tape recorder cannot operate normally. When the voltage of the power supply line 4 falls below a predetermined value, the detection transistor 5 is reversed to a non-conducting state, and the light emitting diode 6 connected to its collector is turned off. As a result, the phototransistor 8 is reversed to a non-conducting state even though the reel shaft is rotating. Therefore, the termination detection circuit 10 is activated, and as described above, the signal from the oscillation circuit 11 is emitted from the speaker 16, and the motor 17 is stopped from rotating. Therefore, the user can recognize when it is time to replace the battery by the signal emitted from the speaker 16.

In the playback operation state, the signal played by the magnetic head is amplified by the preamplifier circuit 12 and then applied to the main amplification circuit 15 via the recording/playback switch 14. After being amplified, the sound is emitted from the speaker 16. In such a reproducing operation state, when the battery 1 is exhausted and the voltage of the power supply line 4 drops, the detection transistor 5 is reversed to a non-conducting state and the light emitting diode 6 is turned off.
When the light emitting diode 6 goes out, the phototransistor 8 becomes non-conductive as described above, so the termination detection circuit 10 is activated and the motor 17 is stopped from rotating. Therefore, since the magnetic tape stops running and there is no reproduction signal, the user can recognize that the battery has run out and needs to be replaced.

In this example, a light emitting diode was used as the light emitting element, but other light emitting elements such as a lamp may also be used.Although a phototransistor was used as the light receiving element, other light receiving elements such as a photodiode may also be used. You can also do that.

As explained above, the power supply voltage check circuit of the present invention uses an oscillating sound to notify when it is time to replace the battery during recording operation, compared to the conventional example in which notification is made by turning on or off a light emitting diode. This allows the user to reliably know when it is time to replace the battery. In addition, when the battery voltage drops below a predetermined value, the system not only generates a warning sound but also stops the motor, which not only prevents noise from being recorded on the magnetic tape, but also prevents unnecessary running of the magnetic tape. It can be prevented. Furthermore, since a detection circuit for detecting the end of the magnetic tape is used, the complexity of the circuit can be avoided, and the practical value of the present invention is very high.

[Brief explanation of the drawing]

The illustrated circuit is one embodiment of the power supply voltage check circuit of the present invention. Explanation of main figure numbers, 1...Battery, 4...Power line, 5...Detection transistor, 6...Light emitting diode, 8...Phototransistor, 10...
Termination detection circuit, 11...Oscillation circuit, 14...Recording/playback selector switch, 15...Main amplifier circuit, 16...
...Speaker, 17...Electric motor, 18...Speed control circuit.

Claims (1)

[Scope of utility model registration request] In a tape recorder that uses a battery as a power source, it is in a conductive state when the voltage across the battery is higher than the voltage value required for normal operation of the tape recorder, and is reversed to a non-conductive state when the voltage falls below the voltage value required for normal operation of the tape recorder. a detection transistor to which a light-emitting element is connected as a light-emitting element; a light-receiving element that is intermittently irradiated with light from the light-emitting element as the reel shaft rotates and repeats conducting and non-conducting operations; and a signal obtained from the light-receiving element. an end detection circuit that detects the end of the tape, and an oscillation circuit that oscillates based on a signal associated with detection of the tape end from the end detection circuit;
It consists of a speaker that emits an oscillation signal from the oscillation circuit, and a speed control circuit that controls the speed of a motor that drives the tape and stops the motor in response to a signal associated with detection of the end of the tape from the end detection circuit. , the light emitting element is turned off by reversing the detection transistor to a non-conducting state as the power supply voltage drops, and the termination detection circuit causes the oscillation circuit to oscillate and stops the motor. Features a tape recorder power supply voltage check circuit.