JPS5931777B2 - tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape recorder, and more particularly to a cartridge type cassette tape recorder.

In a cartridge type cassette tape recorder, if the cassette half is reinstalled into the tape recorder with the slack of the tape inside the cassette half intact when the cassette half is installed or when the tape has stopped running, the tape may be cut or damaged.

Therefore, in conventional tape recorders, mechanical brakes provided on the tape supply side and take-up side are activated at the same time to stop tape running or to drive the tape drive motor for only a certain period of time. These absorb the slack of the tape, but both have complex structures. An object of the present invention is to provide a tape recorder that can prevent tape slack with a simple configuration. The present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram showing one embodiment of the present invention, and in the figure, a tape winding motor 5 is fixed to a chassis □ of a tape recorder. Also provided is a roller 6 which is rotated by the motor 5 and winds up the tape. This configuration is equivalent to that of a conventional cassette tape recorder. Further, a switch drive shaft 2 is provided which is pressed downward by the cassette half 1 against the return force of a spring 3 when the cassette half 1 is mounted on the tape recorder as shown. This drive shaft connects the movable contact C of the switch 4 to the fixed contact NO. When the force set half 1 is removed, the drive shaft 2 is raised by the restoring force of the spring 3, and as a result, the contacts C and NO of the switch 4 are opened. On the other hand, a so-called monostable multivibrator 8 is provided, which has a time constant circuit, takes a stable state and an unstable state determined by the time constant of the time constant circuit, and generates an output according to each state.

The multivibrator 8 has a two-input NAND (NAND)
) A circuit 11, an inverter 12 that inverts the output of the circuit 11, and one end connected to the output of the inverter 12 and the other end connected to a resistor R.
The resistor R1 and the capacitor C1 constitute a time constant circuit of a monostable multivibrator 8, and the time constant RlCl=T of the time constant circuit is a monostable multivibrator 8. Define the vibrator's unstable output pulse width. Furthermore, it also includes an inverter 13 whose input is connected to the connection point between the capacitor C and the resistor R1, and an inverter 14 which inverts the output of the inverter 13 and uses it as one input of the NAND circuit 11. The other input of the NAND circuit 11 is a trigger input terminal IN of a monostable multivibrator, and in this case, a drive signal for the motor 5 is applied. This input terminal 1N is the 1 of the logical sum (0R) circuit 9.
The other input to the 0R circuit 9 is the output α of the inverter 13 which is the output of the multivibrator 8. Then, receiving the output γ of the 0R circuit 9, the motor drive circuit 10
generates an output that drives motor 5. The other end A of the resistor R1 of the multivibrator is the fixed contact NO of the switch 4.
The movable contact C of the plate switch 4 is connected to a power source 15. The operation of the embodiment shown in FIG. 1 will be explained with reference to the timing chart shown in FIG.

In the following explanation, a value approximately equal to the positive power supply voltage +VOD is defined as "1", and a value approximately equal to the ground potential is defined as "0".
It is expressed as ゛. Now, considering the state before the force set half is attached, the winding motor drive signal is not applied to the input terminal 1N, so it is 0. Therefore NA
The output of the ND circuit 11 is necessarily "1", and therefore the output of the inverter 12 is "0", and as a result, the capacitor C
It can be seen that one end of 1 is in a grounded state. In such a state, when the force set half 1 is attached (time TO), the switch 4 is activated and the contacts NO and C are connected, +VI)D of the power supply 15 is applied to the terminal A, and therefore the capacitor C1 is , and is charged for a time T with a time constant RlCl.

Therefore, during this period T, the input of the inverter 13 is approximated to O', so its output becomes 1'. After the period T has elapsed, the terminal voltage of the capacitor C1 is charged to +VDD, that is, to the "1" level, so the inverter 13
The output α becomes O゛゜. On the other hand, this "0" is inverted to "1" by the inverter 14 and applied to other inputs of the NAND circuit 11, but since 1 input 1N is "O", the NAND
The output of the D circuit 11 does not change, so the output of the inverter 13, that is, the output of the monostable multivibrator 8 α
Continue to maintain stable output of ゛. Therefore, the output α of the monostable multivibrator 8 generates an unstable state output ``1'' for a period T from TO when the force set half is installed, and by this ``1'' output, it is transmitted through the 0R circuit 9, the motor, and the drive circuit 10. The take-up motor 5 rotates to absorb the slack of the tape in the force set half. In this case, it goes without saying that the shaft brake on the supply side is operating. Next time t1
When a motor drive input signal of level "1" is applied to the input terminal 1N by, for example, operating the "PLAY" button,
The output γ of the 0R circuit 9 becomes 1'', the motor 5 rotates, and normal tape running is performed.

During this tape running, the brake on the supply side shaft is released. During this time, the NA of monostable multivibrator 8
One input of the ND circuit 11, IN, is 1'', and the output of the inverter 14 is applied to the other inputs, so the output of the NAND circuit 11 is O, and the output of the inverter 12 is 1. Therefore, the electric charge stored in the capacitor C1 of the time constant circuit becomes a discharged state. Naturally, during this period, the output α of the monostable multivibrator 8
This means that a stable output "O" is generated. This is because the power supply voltage +VDD is directly applied to the input of the inverter 13 through the resistor R.

Then, at time T2, when the "STOP" button is pressed to stop tape running, the input terminal IN becomes O', and the brake on the supply side shaft is activated. The output of the NAND circuit 11 is inverted to 1', and the output of the inverter 12 becomes 0', so the connection point between the capacitor C1 and the resistor R1, that is, the input terminal of the inverter 13 becomes O', and from that moment on, the time constant The capacitor will be charged to the "1" level for a period represented by RlCl. Therefore, during the period T from time T2, the output of the monostable multivibrator 8 outputs an unstable output "1", and then returns to a stable output "1". Therefore, the take-up motor 1 drive signal is
Even if ``, the ``1'' output of the monostable multivibrator 8 is generated at the other input α of the 0R circuit 9 for a period T, so the take-up motor rotates due to the ``1'' output during this period T. On the other hand, since the brake is activated on the supply side shaft, it can be seen that the slack in the tape is eliminated.In the above embodiment, the case where a take-up motor is installed has been explained, but if the motor is installed on the tape supply side. Of course, the present invention can also be applied to the supply motor of a tape recorder equipped with the tape recorder.
``LAY'', ``FF'', and ``REW'' tape running can be considered, so if the input terminal 1N part in Fig. 1 is replaced with a 3-input 0R gate circuit, the above three running states can be changed to a stopped state. Also, the slack of the tape can be absorbed.

It goes without saying that the two-input NAND gate, inverter circuit, and OR circuit in the above embodiments can be constructed using bipolar transistors, diodes, or field effect transistors.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a timing waveform diagram explaining the operation of FIG. 1.

Claims (1)

[Scope of Claims] 1. It has a motor that runs the tape of the cassette half, a trigger input terminal to which a drive signal is applied to the motor, an output terminal, and a time constant circuit. When the motor drive signal applied to the trigger input terminal ends or power is applied to the time constant circuit, the output terminal becomes unstable for a period determined by the time constant of the time constant circuit. a monostable multivibrator that generates an output, a switch that applies power to the time constant circuit of the multivibrator when the cassette half is attached to a tape recorder, and a switch that connects the motor drive signal to the output of the multivibrator. A tape recorder comprising: a gate circuit that generates an OR output; and a motor drive circuit that receives the output of the gate circuit and drives the motor. 2. The tape recorder according to claim 1, wherein the time constant circuit includes a series connection circuit of a capacitor and a resistor, and the capacitor is charged from the power source via the resistor and the switch. 3. The monostable multivibrator includes a first inverting circuit whose input is connected to the series connection point of the capacitor and the resistor of the time constant circuit, and whose output is connected to the output end of the multivibrator, and the first inverting circuit. a second inverting circuit that inverts the output of the second inverting circuit, a gate circuit that outputs a NAND of the output of the second inverting circuit and the motor drive signal applied to the trigger input terminal, and the NAND gate. a third circuit which inverts the output of the circuit and whose output end is connected to the capacitor;
3. The tape recorder according to claim 2, further comprising an inverting circuit.