JPS626582Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic stop circuit for automatically detecting the end of a tape and automatically stopping a tape recorder mechanism.

Conventionally, the automatic stop circuit of a tape recorder has a configuration excluding the part surrounded by a two-dot chain line in FIG. 4 is connected, the plunger 2 operates only once by a single signal applied within the time set by the monostable multivibrator 4 after detecting the end of the tape, and the mechanism of the tape recorder is stopped. I was pushing him. However, if the mechanism of the tape recorder has some kind of temporary failure (for example, the mechanism is jammed, etc.), the plunger 2
If the machine does not stop automatically due to the situation where the machine cannot operate even if the machine is energized, there is a risk that the mechanism may be damaged or the tape may be cut.

The present invention has been developed in view of these points, and if the mechanism does not stop due to some temporary failure, the plunger is energized multiple times, and if the plunger does not stop even after multiple energizations, the subsequent energization is The aim is to improve the reliability of automatic stopping. An embodiment of the present invention will be described below in detail with reference to the drawings. 5 is a magnet that rotates in response to the running of the tape, 6 is an element that detects magnetic changes caused by the magnet 5, and its output side detects the end of the tape. Connected to the circuit 1 input side. 7 is an astable multivibrator, and 4 is a monostable multivibrator, both of whose input sides are connected to the output side of the tape end detection circuit 1, and whose output sides are connected to the input side of an AND circuit 8, respectively. The output side of the AND circuit 8 is an NPN type transistor 3 for driving the plunger 2.
The collector terminal of the transistor 3 is connected to the output side of the plunger 2,
The emitter terminal is grounded. In addition, the power supply (+
B) is supplied to the plunger 2 and connected to the tape end detection circuit via the switch 9, which opens and closes in response to the operation of the plunger 2 (it is on when the plunger 2 is not in operation and is off when it is in operation). 1, supplied to the astable multivibrator 7 and monostable multivibrator 4, respectively. The above is the main circuit configuration of the present invention, and its operation will be explained below.

FIG. 2 is a time chart showing the state of pulses at each point in the circuit. When the tape reaches its end and the rotation of the magnet 5 stops, the output side of the tape end detection circuit 1 goes to a high (H) level. Thus, a plurality of square waves are generated on the output side of the astable multivibrator 7, and one square wave is generated on the output side of the monostable multivibrator 4. Therefore,
An H level is output to the output side of the AND circuit 8 only when the output of the astable multivibrator 7 becomes H level while the output of the monostable multivibrator 4 is at H level, and in response, the transistor 3 It will work. Then, the plunger 2 is energized several times, the plunger 2 operates, the tape recorder stops, and the switch 9 is turned off. Note that normally, in FIG. 2, the tape recorder is in a stopped state at the time when the plunger 2 is operated by the first pulse.

As described above, according to the present invention, by operating the monostable multivibrator and the astable multivibrator when detecting the end of the tape, the oscillation operation of the astable multivibrator is prevented during the operation period of the monostable multivibrator. The configuration is such that the plunger is energized multiple times by the output of the responsive AND circuit, so if the mechanism does not stop due to some temporary failure with a single energization of the plunger, the energization is repeated multiple times. If the plunger does not stop even after being energized multiple times, subsequent energization can be stopped to prevent excessive heat generation of the plunger and battery power consumption, improving the reliability of automatic shutdown. .

[Brief explanation of the drawing]

The drawings all illustrate the present invention; FIG. 1 is a block diagram and FIG. 2 is a time chart. 1... Tape end detection circuit, 2... Plunger, 3... Transistor, 4... Monostable multivibrator, 7... Astable multivibrator,
8...AND circuit.

Claims (1)

[Scope of utility model registration request] In the automatic stop circuit of a tape recorder that electrically detects the tape end and stops the mechanism using a plunger, an astable multivibrator and an astable multivibrator are connected between the output side of the tape end detection circuit and the input side of the AND circuit. The monostable multivibrator is connected in parallel, and the output side of the AND circuit is further connected to the base of the plunger driving transistor, so that when the end of the tape is detected, the monostable multivibrator and the astable multivibrator are operated. An automatic stop circuit for a tape recorder, characterized in that, during the operation period of the monostable multivibrator, a plunger is energized multiple times by the output of an AND circuit responsive to the oscillation operation of the astable multivibrator.