JPS5912770Y2 - Tape recorder control circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tape recorder having a function of being able to record by changing the running speed of a magnetic tape.

When performing a playback operation on a tape recorder equipped with such a function, it is necessary to use the same running speed as the recording speed, so it is necessary to check at what running speed the magnetic tape to be played back was recorded. .

Furthermore, if the running speed of the magnetic tape is changed during the recording operation, the running speed will differ within the same tape.

The present invention provides a control circuit suitable for a tape recorder having a function of automatically detecting the running speed of a magnetic tape during recording.

The illustrated circuit is one embodiment of the present invention, and in the figure,
Reference numeral 1 designates a recording signal input terminal to which a recording signal is applied, 2 an amplifier circuit, 3 a recording amplifier circuit, 4 a bypass oscillation circuit that operates during bias operation during recording operation, and 5 a recording magnetic head.

6 is an interlocking switch that is switched in conjunction with a speed changeover switch (not shown) that changes the running speed of the magnetic tape; the movable contact piece 6a, the fixed terminal 6b are open, and the fixed terminal 6C is open. It is connected to an input terminal of an inverter 8 via a capacitor 7.

9 is an AND circuit 10.11. The inverter 12, a capacitor 13, etc. are used for inversion rotation, and when the output signal of the inverter 8 is applied, the inversion operation is performed for a predetermined period of time, during which time an H (high) level signal is output to the output terminal of the inverter 12. It is configured.

Reference numeral 14 denotes a muting transistor whose collector-emitter path is connected between the signal transmission line 15 on the input side of the amplifier circuit 2 and the ground, and which bypasses the signal of the signal transmission line 15 in the on state. The base is resistance 1
6 to the output terminal of the inverter 12.

Reference numeral 17 denotes a detection signal generation circuit that outputs a detection signal for detecting the running speed of the magnetic tape, and its output terminal is connected to the signal transmission line 19 of the recording circuit via a level setting variable resistor 18.
It is connected to the.

Reference numeral 20 denotes a control transistor that controls the operation of the detection signal generation circuit 17 and turns the detection signal generation circuit 17 into an operating state when it is in an on state. It is connected.

22 is a switch that is closed when the slide board on which the magnetic head etc. are fixed is slid to the performance position, and is connected to the fixed end A 6C and the inverter 8 together with the capacitor 23.
is connected between.

The present invention is constructed as described above, and the dynamics will be explained next.

If a recording operation is performed while the interlocking switch 6 is in the alternative position shown, the recording state is established and the switch 22 is closed.

However, since power is not applied to the fixed terminal 6C, the inverting circuit 9 does not perform an inverting operation.

Therefore, the muting transistor 14 is never turned off, and the detection signal generation circuit 17 is never put into operation.

Therefore, the recording signal applied to the recording signal input terminal 1 is amplified by the amplifier circuit 2 and the recording amplifier circuit 3, and then applied to the recording magnetic head 5 together with the bias signal from the bias oscillation circuit 4 to be recorded on the magnetic tape. be done.

Next, a case will be explained in which the running degree of the magnetic tape is changed in such a recording state.

When the speed changeover switch is operated, the movable contact piece 6d of the interlocking switch 6 is switched from the fixed terminal 6b to the fixed terminal 6C side in conjunction with the switching of the speed changeover switch.

As a result, a differentiated H level signal is applied to the input terminal of the inverter 8, so that an L (lower) level signal is output from the output terminal of the inverter 8.

Previous statement [When an L level signal is output from the inverter 8, the output signal of the AND circuit 10 to which that signal is applied becomes H
The level is inverted to L level.

Therefore, the inverting circuit 9 inverts for a predetermined period of time, during which the output signal of the inverter 12 becomes H level.

As a result, the muting transistor 14 and the control transistor 20 to which the H level signal is applied to their bases are turned on.

When the muting transistor 14 is turned on, the signal on the signal transmission line 15 is bypassed through the collector-emitter path of the transistor 14, so that the recording signal applied to the recording signal input terminal 1 is output from the amplifier circuit 2. It will not be done.

Further, when the control transistor 20 is turned on, the detection signal generation circuit 17 is activated and sends a detection signal to the signal transmission line 19.

Therefore, when the inverting circuit 9 performs an inverting operation and an H level signal is output from the inverter 12, the recording signal applied to the recording signal input terminal 1 during that time is bypassed, and the detection signal which is the output of the detection signal generation circuit 17 is Only magnetic recording head 5
is applied and recorded on magnetic tape.

Then, after a predetermined period of time has elapsed, the inverting circuit 9 returns to the stable state, so the output of the inverter 12 becomes L level, and the muting transistor 14 turns off.
Furthermore, the detection signal generation circuit 17 becomes inactive.

Therefore, the tape recorder enters a normal recording state, and the recording signal applied to the recording signal input terminal 1 is guided to the recording magnetic head 5 and recorded on the magnetic tape without being bypassed.

As described above, when the running speed of the magnetic tape is changed in the recording operation state, the detection signal is recorded on the magnetic tape for a predetermined period of time, and then the recording signal is recorded.

Next, a case will be described in which a recording operation is performed when the movable contact piece 6d of the interlock switch 6 is on the fixed terminal 6C side.

When the switch 22 is in the stopped state, the switch 22 is in the open state, and when a recording operation is performed in this state, the slide board on which the magnetic head etc. are fixed slides to the performance position and enters the recording operation state. The switch 22 is closed in accordance with the sliding displacement of the slide board.

As a result, a differentiated H level signal is applied to the input terminal of the inverter 8, an L level signal is output from the output terminal, and the inverting circuit 9 performs an inverting operation.

Therefore, in the same way as when the above-mentioned interlocking switch 6 is switched in the recording operation state, the normal recording operation is performed after the detection signal is recorded on the magnetic tape for a predetermined period of time.

As explained above, the present invention is characterized in that when the running speed of the magnetic tape is changed in the recording operation state, the detection signal is recorded on the magnetic tape for a predetermined period of time. It is ideal as a control circuit for a tape recorder that has an automatic detection function.

BRIEF DESCRIPTION OF THE DRAWINGS The illustrated circuit is one embodiment of the control circuit of the present invention. Explanation of main drawing numbers, 1... Recording signal input terminal, 3...
Recording amplifier circuit, 5... Recording magnetic head, 6...
Interlocking switch, 9... Inversion circuit, 14... Muting transistor, 17... Detection signal generation circuit.

Claims (1)

[Scope of utility model registration request] In a tape recorder capable of recording at least different first and second tape speeds, an interlocking switch that is switched in conjunction with a changeover switch that switches the tape running speed, and a switch that switches from the first tape speed to the second tape speed. an inverting circuit that outputs a control signal by inverting for a predetermined time when the interlocking switch is switched; a detection signal generating circuit that operates and outputs a detection signal when the control signal from the inverting circuit is applied; and the inverting circuit. When a control signal from the inverting circuit is applied, the muting transistor turns on and bypasses the recording input signal, and when a control signal is output from the inverting circuit, the muting transistor outputs the recording input signal. 1. A control circuit for a tape recorder, characterized in that the detection signal from the detection signal generation circuit is bypassed and guided to a recording circuit, thereby recording the detection signal on a magnetic tape.