JPS6319945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for a key-off eject type tape recorder configured to automatically eject a tape cassette when the main switch is turned off. An object of the present invention is to provide a control circuit for a tape recorder that can reduce the labor cost of a large current generated by a motor used for an eject operation that occurs due to uncertainty in the eject operation.

Generally, a car-mounted tape recorder enters a tape playback state when a tape cassette is attached to the tape recorder main body, and during this tape playback operation, the power is often turned off, that is, the car's engine key is turned off. In such a case, if the tape cassette remains attached to the tape recorder body, the pinch roller will be left in pressure contact with the capstan shaft for a long time, causing deformation of the pinch roller and damaging the engine. A method is adopted in which the tape cassette is ejected when the key is turned off, that is, the key is ejected. In such a key-off eject type tape recorder, when the engine key is turned off, a trigger mechanism is activated by a plunger, and this trigger mechanism connects a motor to an eject mechanism to utilize the rotational force of the motor. It is known that the tape cassette is ejected from the tape recorder main body by driving the eject mechanism. By the way, as mentioned above, in the case where the tape cassette is ejected using the rotational force of the motor, if the motor is stopped at the same time as the engine key is turned off, the tape cassette cannot be ejected. The motor used for this purpose is backed up from the power supply circuit (battery) regardless of the car's engine key, and the tape cassette eject operation starts at the same time as the engine key is turned off, and a mechanical switch is activated at the end of the eject operation. It is necessary to configure the system so that the backup power line is cut off and the motor is stopped. However, in the above-mentioned key-off eject type tape recorder that uses the rotational force of the motor, if the tape in the tape cassette becomes entangled with the tape recorder main body for some reason, or if the eject mechanism is malfunctioning, the tape cassette will be removed. There was a problem in that the motor continued to rotate because it was not completely ejected and the backup power supply line could not be cut off by the mechanical switch. In other words, when the mechanical switch is turned off, the engine key is turned off to eject the tape cassette, but even though the engine key is turned off, the mechanical switch is not turned off and power is supplied to the motor. There was a problem that if I continued to do so, the car's battery would drain over a long period of time.

The present invention eliminates such conventional drawbacks, and the present invention will be described below with reference to drawings of embodiments.

The drawing shows one embodiment of the control circuit for the tape recorder of the present invention, and in the drawing, 1 is a car battery, and _S1 is a switch that is turned on and off in connection with the installation and removal of a tape cassette from the tape recorder body. , S ₂ is the engine key, 2 is the transistor Q ₁ ,
A timer switch circuit consisting of _Q2, etc., and 3 a motor whose operation is controlled by the timer switch circuit 2. The timer switch circuit 2 has a transistor Q ₁ having a resistor R ₁ connected between its base and emitter, and a transistor Q ₂ having a time constant circuit including a capacitor C ₂ and resistors R ₄ and R ₃ at its base.
The collector of the transistor Q ₂ is connected to the base of the transistor Q ₁ via a resistor R ₂ , and the emitter of the transistor Q ₂ is grounded.
Further, the emitter of the transistor _Q1 is connected to the positive pole of the battery ₁ via the switch S1, and the collector is connected to the motor 3. Also, the positive terminal of the battery 1 above is a diode.
It is connected to the connection point A of resistors R ₃ and R ₄ connected to the base of transistor Q ₂ via D ₁ . _Q3 ,
Q ₄ and Q ₅ are switching transistors, and the emitter of the switching transistor Q ₃ is a transistor constituting the timer switch circuit 2.
It is connected to the emitter of _Q1 , and also to the base of the switching transistor _Q4 and the collector of the switching transistor _Q5 via a resistor _R8 . The emitter of the switching transistor _Q4 is connected to the base via a resistor _R5 , and the base is connected via a resistor _R6 to the collector of the switching transistor _Q4 whose emitter is grounded. Also, the switching transistor whose emitter is grounded
The base of Q ₅ is connected to the diode D ₁ above through the resistor R ₉
It is connected to the anode side of the circuit and grounded via a resistor _R10 . The collector of the switching transistor _Q3 is grounded via a resistor _R7 . The collector of the switching transistor Q ₃ is connected to the base of a transistor Q ₆ via a differentiator circuit consisting of a capacitor C ₃ and a resistor R ₁₁ , and a resistor R ₁₂ , and the emitter of this transistor Q _{6 is connected to the base of a transistor Q 6} whose emitter is grounded. ₇ and both these transistors
A plunger 4 is connected between the collectors of Q ₆ and Q ₇ and the positive pole of the battery 1.

In the control circuit configured as described above, when the engine key _S2 is off and no tape cassette is attached to the tape recorder body, the switch _S1 is also off, and each power line of the timer switch circuit 2 is turned off. a and b are off. Therefore, transistors _Q1 to _Q7 are off, motor 3 does not rotate, and plunger 4 is not driven. On the other hand, when switch _S1 is off (when no tape cassette is installed) and engine key _S2 is turned on, the a power line of timer switch circuit 2 is turned on, and the base of transistor _Q2 that makes up this circuit is biased. Transistor Q ₁ is in an off state, and the base of transistor Q ₅ is biased, but transistors Q ₃ and Q ₄ are in an off state, and similarly, motor 3 and plunger 4 are not driven. And engine key S ₂
When the tape cassette is attached to the tape recorder main body when the switch is on, switch _S1 is turned on, so the power line of the timer switch circuit 2 is turned on, and the transistor constituting the timer switch circuit 2 is turned on.
Q ₁ and Q ₂ are each turned on, and motor 3
is supplied with power and begins to rotate. In other words, the tape recorder main body is in a tape playback state. However, in this tape playback state, the transistor
Since _Q5 is in the on state and the base of the above transistor _Q4 is grounded, the above transistor
Q ₃ and Q ₄ are in the off state, and the plunger 4 is not driven. Next, in the tape playback state described above, when the power line a of the timer switch circuit 2 is turned off, that is, when the engine key _S2 is turned off, first, the bias is no longer applied to the base of the transistor _Q5 , and the voltage becomes OV. The transistor Q ₅ is turned off, which causes the base of the transistor Q ₄ to be biased by the resistor R ₈ , turning on the transistor Q ₄ , and the base of the transistor Q ₃ is biased, turning the transistor Q ₃ on. The rising potential appearing at the collector of the transistor Q ₃ becomes a positive pulse through a differentiator circuit consisting of a resistor R ₁₁ and a capacitor C ₃ , and this positive pulse is applied to the transistor Q ₆ through a resistor R ₁₂ . In order to do this, transistors Q ₆ and Q ₇ are turned on, and the plunger 4 is energized. When the plunger 4 is driven, a trigger mechanism is activated, and the trigger mechanism connects the motor 3 to the eject mechanism, and the rotational force of the motor is used to drive the eject mechanism. Remove the tape cassette from the tape recorder main body. Also, when the eject operation of this tape cassette is completed, the above switch _S1
b of timer switch circuit 2 to be turned off.
The power line is turned off and the timer switch circuit 2
By turning off the transistors Q ₁ and Q ₂ constituting the motor, the power supply to the motor 3 is stopped, and the rotation of the motor 3 is stopped.

In addition to turning off the engine key _S2 , when the separately provided manual eject switch _S3 is turned on, the transistors _Q6 and _Q7 are turned on, thereby driving the plunger 4, which also drives the tape cassette. Since the engine key S ₂ is turned on and the a power line of the timer switch circuit 2 is turned on, the transistor constituting the timer switch circuit 2 Needless to say, a bias is applied to the base of _Q2 .

By the way, if the tape in the tape cassette gets tangled with the tape recorder body for some reason or the eject mechanism malfunctions during the eject operation when engine key S ₂ is turned off, switch S ₁ will be turned off. The on state continues without any problem, and the motor 3 continues to rotate, but since the a power line of the timer switch circuit 2 becomes OV when the engine key S ₂ is turned off, the charge accumulated in the capacitor C ₂ is the resistance R ₃ ,
It is discharged with a time constant of R ₄ and finally the transistor
Turn off _Q2 . Therefore, transistor Q ₂
By turning off, the transistor _Q1 is turned off, and the current to the motor 3 can be cut off even though the switch _S1 is in the on state.

Although the above embodiment has been described with respect to an in-vehicle tape recorder, it can also be applied to a normal tape recorder, and in this case, the engine key switch may be replaced with a power switch.

As described above, according to the present invention, a switch that is turned on and off in response to attachment and detachment of a tape cassette from the tape recorder body is connected to the battery, and is also used for the eject operation of the switch and the tape cassette. A timer switch circuit is inserted between the main switch (power switch, engine key switch) and the motor to turn off after a predetermined time, so that the tape cassette will not be completely ejected when the main switch is turned off. Even if the switch that responds to this is not turned off, the power to the motor can be cut off after a predetermined time determined by the timer switch circuit, and the motor continues to rotate and the large current from the backup power source is generated for a long time. This has the advantage of reducing labor costs and effectively preventing battery drain.

[Brief explanation of the drawing]

The drawing is a circuit connection diagram showing one embodiment of a control circuit for a tape recorder according to the present invention. 1... Battery, 2... Timer switch circuit, 3... Motor, 4... Plunger, Q ₁ ~
Q ₇ ...transistor.

Claims (1)

[Claims] 1 A tape constructed in such a way that a motor and an eject mechanism are connected by a plunger activated when the main switch is turned off, and the tape cassette is automatically ejected from the mounting position of the tape recorder body using the rotational force of the motor. In the recorder, a switch that is turned on and off in response to the operation of attaching and detaching the tape cassette to the tape recorder main body is directly connected to the battery, and a switch that is turned on and off in response to the operation of attaching and detaching the tape cassette to the tape recorder body is directly connected to the battery, and a switch that is turned on and off in response to the operation of the main switch being turned off is connected between the switch and the motor. 1. A control circuit for a tape recorder, comprising a timer switch circuit that is turned off after a predetermined period of time.