JPS6336502Y2 - - Google Patents

Description

[Detailed description of the invention] This invention continuously turns off the switching transistor connected to the power supply line and electrically shuts it off when the tape is wound to the end, and operates the pause switch. This invention relates to a pause circuit for a tape recorder that can temporarily stop the tape.

In a tape recorder, it is generally known that a tape end detecting circuit detects that the tape has been wound to the end, and operates a plunger accordingly to shut off the tape.

However, since the tape recorder uses a plunger that requires a relatively large current to shut off, this is not possible with a portable tape recorder that uses a battery as a power source.

Therefore, a switching transistor is connected in series to the power supply line, and the switching transistor is a control transistor that is controlled by a signal from the tape end detection circuit, and is turned off continuously after the end of the tape is detected. When the tape is put into a pause state where the power supply voltage is cut off and the tape is shut off purely electrically, it is temporarily stopped.
If the power supply voltage to an audio circuit such as an amplifier is cut off, the next time the pause state is released, the audio circuit will start up slowly, causing distortion in the audio signal.

The present invention eliminates such drawbacks and provides a tape recorder pause circuit that turns on the switching transistor in the pause state to cut off the power supply voltage to the motor while keeping the power supply voltage supplied to the audio circuit. The present invention will be explained below with reference to the drawings.

Reference numeral 1 designates a tape end detection circuit, which includes a tape switch 4 which is turned on and off by a cam 3 provided eccentrically on the reel shaft 2, diodes 5 and 6, resistors 7 and 8, a capacitor 9 and a transistor 10. 11
is a control transistor; 12 and 13 are controlled transistors controlled by the control transistor 11;
A switching transistor 14 is connected in series to a power supply line 16 having a battery 15 at one end, and is controlled by the controlled transistor 13.

Reference numeral 17 denotes a tape recorder section connected to the power supply line 16 after the switching transistor 14, and is connected to the power supply line 16 via an audio circuit 21 consisting of a microphone 18, a magnetic head 19, an amplifier circuit 20, etc., and a pause switch 22. and a motor 23 selectively connected to. The pause switch 22 includes a common contact 24 connected to the motor 23, a first contact 25 connected to the power supply line 16, and a second contact 26 connected to the base of the controlled transistor 12.

Next, the operation of the pause circuit of the tape recorder of the present invention will be explained. During tape recording or playback, the cam 3 is also rotated as the reel shaft 2 rotates, and the tape switch 4 is turned on and off. Therefore, the capacitor 9 is repeatedly charged and discharged, and the charging voltage of the capacitor 9 is equal to the on-voltage of the transistor 10. It is not raised to the level of

Therefore, the transistor 10 is turned off, the control transistor 11 and the controlled transistor 12 are turned off, the controlled transistor 13 is turned on, the switching transistor 14 is also turned on, and the voltage from the battery 15 is applied to the tape recorder section 17 . The audio circuit 21 and the movable contact piece 28 are then supplied to the motor 23 via a pause switch 22 located between the common contact 24 and the first contact 25.

As the winding of the tape 27 progresses and the tape 27 is wound to the end, the end of the tape is fixed to the reel shaft 2, so the rotation of the reel shaft 2 is forcibly stopped and the tape switch 4 is turned off. remain as they were.

Then, the diode 5 is turned off and the capacitor 9 only performs charging, so that the charging voltage of the capacitor 9 eventually becomes equal to or higher than the on-voltage of the transistor 10, so that the transistor 10 is turned on. Then, the control transistor 11 and the controlled transistor 1
2 is also turned on, turning off the controlled transistor 13 and the switching transistor 14, thereby cutting off the voltage to the tape recorder section 17 .

If left as is, this state will not change and the switching transistor 14 will remain off and the tape recorder will be rendered inactive. At this time, a bias current flows through the transistor 10, the control transistor 11, and the controlled transistor 12, but the bias resistance is made large so that only the minimum bias current necessary to turn on each transistor flows. The consumption of the battery 15 is extremely small.

By the way, there are times when it is desired to temporarily stop the tape 27 during recording or playback. In that case, move the movable contact piece 28 of the pause switch 22 to the common contact 2 from the illustrated state.
4 and the second contact 26, the voltage applied to the motor 23 from the battery 15 is cut off.
The rotation of the motor 23 is stopped, and the tape 27 is not run but is in a pause state.

At this time, the rotation of the reel shaft 2 is also stopped, so
Transistor 10 turns on and control transistor 1
1 is also turned on, but since the base bias circuit of the controlled transistor 12 is grounded via the motor 23, the controlled transistor 12 is not turned on. Therefore, the controlled transistor 13 remains on, and the switching transistor 14 also remains on, so that the voltage remains applied to the audio circuit 21 of the tape recorder section 17 . Therefore, when you release the pause state,
When the motor 23 starts rotating, the microphone 18
The information picked up is normally amplified from the beginning by the amplifier circuit 20 and recorded onto a tape via the magnetic head 18.

As described above, the pause circuit of the tape recorder of the present invention has a switching transistor connected in series to the power supply line, the audio circuit of the tape recorder section is directly connected to the latter stage of the switching transistor, and the motor is also connected via the pause switch. The pause switch is connected to the latter stage of the switching transistor, and has a first state in which the motor is connected to the power supply line, and a second state in which the motor is disconnected from the power supply and the controlled transistor is forcibly locked in a tape end non-detection state. Since it can be switched between two states, the switching transistor shuts off the tape recorder section when the tape has been wound to the end, and the motor can also be stopped when the tape is temporarily stopped by a pause operation. Since the audio circuit is left in operation, it is possible to obtain a good rise characteristic when releasing the pause in a device that shuts off purely electrically, which is practical.

[Brief explanation of the drawing]

The figure is a pause circuit diagram of the tape recorder of the present invention. 1 ... Tape end detection circuit, 11... Control transistor, 12, 13... Controlled transistor,
14...Switching transistor, 16...Power line, 17 ...Tape recorder section, 21...
Audio circuit, 22...pause switch, 23...motor.

Claims (1)

[Scope of utility model registration request] a tape end detection circuit that detects the end of the tape;
A controlled transistor that is controlled by a signal detected by the tape end detection circuit, and a switching transistor that is connected in series with a power supply line and that is continuously turned off after the controlled transistor detects the end of the tape. and a tape recorder section having an audio circuit directly connected downstream of the switching transistor of the power supply line, and a motor connected via a pause switch, the pause switch being a first switch that connects the motor to the power supply line. the first state and a second state in which the motor is disconnected from the power supply line, a bias circuit of the control or controlled transistor is connected to the motor, and the control or controlled transistor is forcibly locked in a tape end non-detection state; A tape recorder pause circuit featuring: