JPS5923237Y2 - Tape recorder control device - Google Patents

Description

[Detailed Description of the Invention] The present invention is a control device for a tape recorder, particularly for turning on a mute or bias switch.

The present invention relates to a control device that controls OFF switching timing.

In tape recorders, a bias switch is used to control the supply of bias current in order to prevent unnecessary magnetization of the recording head due to bias current when switching between recording mode and stop mode, or between stop mode and recording or playback mode. At the time of switching, a mute switch or the like is provided to prevent unnatural recording/reproducing signals from being generated due to transient operations when the recording or reproducing head comes into contact with and separates from the magnetic tape.

Conventionally, in the case of a cassette recorder, for example, switching of these switches has been carried out mechanically in relation to a displacement member such as a head board that advances or retreats depending on the mode, or electrically by using a logic circuit. It is something.

However, since the switching timing of the switch is greatly influenced by the position of the switch with respect to the displacement member, it is not only difficult to set accurately and easily, but also when switching is performed mechanically, switching is not performed reliably due to play in the displacement member, etc. There are also concerns that there will be no problem, and those that use logic circuits have the disadvantage of being expensive.

The present invention solves these conventional drawbacks and will be described in detail below with reference to the drawings.

The figure shows an embodiment in which the device of the present invention is applied to a cassette recorder, in which an erasing head 1, a recording/reproducing head 2, and a magnetic tape ( The head substrate 7, on which pinch rollers 6 for transferring (not shown) are mounted in cooperation with the capstan 5, is connected to the head substrate 7 by guide pins 8 set in the chassis 3 and guide holes 9 formed in the head substrate 7. The chassis 3 is guided so that it can take forward or backward positions relative to the magnetic tape.
It is located in

An abbreviated lever 1 rotatably supported by a shaft 10 on a chassis 3
A required coil spring 13 is stretched between the tip of one arm 12 of the lever 11 and the head substrate 7, and a rolling contact roller 15 is rotatably supported 16 at the tip of the other arm 14 of the lever 11. ing.

The rolling contact roller 15 abuts against a circumferential surface 19 of a cam disk 18 rotatably supported by the chassis 3.

Symbols a-Lf attached along the circumferential surface 19 of the cam disc 18 are rotated so that the position of each symbol is the rolling contact roller 1.
This is to explain the mode of the recorder when it reaches the position where it collides with the symbol a.

b and f indicate the stop, fast forward, and play mode positions, respectively; symbols d and e indicate the closed positions of the bias switch and mute switch, which will be described later; and symbol C indicates the position where the recording/reproducing head 2 comes into contact with and separates from the magnetic tape. The positions of symbols a and b have the same diameter with respect to the axis 17, and the diameter gradually increases from before the position of symbol C toward the position of symbol f, reaching the maximum at the position of symbol f. It has a cam shape.

The cam disk 18 is rotated by a control motor M which is controlled via a necessary speed reduction means (not shown) in accordance with the operation of a mode selection switch such as playback or stop.

Mode selection switches SW1 to SW3 correspond to stop, fast forward, and playback modes, respectively, and stop switch SW1,
One contact of the fast-forward switch SW2 and the playback switch SW3 are both connected to one input terminal 21 of the arithmetic circuit 20, and the other contact is connected to the variable terminals T1 to T3 of the variable resistors VR1 to vR3 forming the reference signal generating means 23. are connected to each.

Variable resistors VR1 to vR3 are connected in parallel between power supplies +E and -E, and their variable terminals T1 to T3 generate reference voltages v1 to 3, which serve as reference signals, respectively.

The other input terminal 22 of the arithmetic circuit 20 is connected to a variable terminal Tc of a rotary variable resistor VRc connected between power supplies +E and -E to form a variable voltage generating means 24.

The variable terminal Tc is configured to operate in conjunction with the control motor M to obtain a required variable voltage Vc.

The calculation circuit 20 compares and calculates the levels of the reference voltages v1 to V3 applied to the surface input terminals 21 and 22 and the changing voltage Vc, and when the two voltage values are equal, the control motor M is stopped with a control output of 0, When the reference voltages v1 to V3 are larger than the changing voltage Vc, a first control output is output to rotate the control motor M in the forward direction, and in the opposite case, a second control output is output to rotate the control motor M in the reverse direction.

The cam disk 18 and the variable terminal Tc are arranged so that the cam disk 18 rotates counterclockwise in response to the positive rotation of the control motor M, and the variable terminal Tc is displaced in the direction from the negative power source -E to the positive power source +E. , and the cam disk 18 and the variable terminal Tc are respectively associated with each other so as to be displaced in the opposite direction to the reverse rotation of the control motor M.

The changing voltage Vc obtained from the changing signal generating means 24 is applied to the mute switch S1. of the recording/reproducing circuit 25. First input terminals 28 and 29 of each of the comparison circuit 26 for the mute switch and the comparison circuit 27 for the bias switch, which control ON/OFF switching of S2 and the bias switch S3.
is applied to

Each of the second input terminals 30, 31 of the comparator circuits 26, 27 is connected to a variable DC power source 32, 33, which is configured to be adjustable.
The reference voltage v4. is set to a more required level. V5 is applied.

Comparison circuits 26 and 27 respectively output a varying voltage Vc and a reference voltage V4. ■ Compare and calculate the levels of 5, and the changing voltage Vc is the reference voltage V4. When each signal is larger than the level of V5, an output signal of the required polarity and level is output, and relays RL1 to RL3 forming the control circuit are activated to switch S1.
~ S3 is turned ON, and conversely, when each is small, the output is O and relays RL1 to RL3 are inactive and switches S1 to S3 are turned on.
Turn off.

The recording and reproducing switch S4 of the recording and reproducing circuit 25 is normally connected to the reproducing side p, and is switched to the recording side R in the recording mode selection operation.

In the playback mode, the playback signal from the recording/playback head 2 is guided to the output terminal 35 via the switch S4, the playback amplifier 34, and the mute switch S1, and in the record mode, the recording signal input from the input terminal 36 is guided to the output terminal 35 through the switch S4, the playback amplifier 34, and the mute switch S1. A bias current supplied from a bias circuit 38 is superimposed on the recording amplifier 37, and the superimposed bias current is supplied to the recording/reproducing head 2 via the switch S4, and is recorded on the magnetic tape.

The bias switch S3 is arranged between the bias circuit 38 and the bias circuit power supply Vcc, and controls the power supply to the bias circuit 38.

The reference voltages ■1 to V3 generated in response to mode selection and the reference voltages ■4°V5 applied to the comparator circuits 26 and 27 are as follows:
The cam disc 18 is rotated by the control motor M to each symbol position of a, b, d, e, and f. When the reference voltage V1 . v2. v5. ■
4 and H■ 3 D etc. The changing voltage Vc is the changing signal generating means 2.
As shown in the variable terminal Tc of No. 4, the variable terminal Tc is displaced in relation to the rotation of the control motor M.

In the device of the present invention having the above configuration, the stop switch SW1 of the mode selection switch is closed, the changing voltage Vc is equal to the value of the reference voltage ■1, the control motor M is stopped, and each component is stopped at the position shown in the figure. Playback switch SW from mode
3 and selects the reproduction mode, the reference voltage v3 applied to the input terminal 21 of the arithmetic circuit 20 is applied to the input terminal 22.
Since the value is larger than the value of the changing voltage Vc applied to the variable voltage Vc, the arithmetic circuit 20 outputs the first control output to drive the control motor M in forward rotation.

Therefore, the variable terminal Tc changes in the direction toward the positive power source +E, and the cam disk 18 rotates counterclockwise.

During the displacement of the variable terminal Tc and the rotation of the cam disk 18, the lever 11 moves from the time when the position before the position C of the cam disk 18 reaches the position where it collides with the rolling contact roller 15. Since the head base plate 7 is rotated clockwise by the cam shape, the head base plate 7 is driven via the spring 13 from the retracted position, which is the stop position, to the forward position, which is the regeneration operation position, and the position indicated by symbol C reaches the abutting position. When the recording/playback head 2
contacts the magnetic tape and moves forward until the position of symbol f reaches the abutting position.

On the other hand, the displacement of the variable terminal Tc has not yet reached the point where the changing voltage Vc is equal to the value of the reference voltage V4 when the position of symbol C reaches the matching position, and the variable terminal Tc is further displaced and the changing voltage Vc is not yet equal to the value of the reference voltage V4. When Vc exceeds the value of reference voltage V4, comparator circuit 26 outputs an output signal to operate relays RL and RL2 and close mute switches S1 and S2.

The rotation of the cam disk 18 and the displacement of the variable terminal Tc are controlled by the control motor when the value of the changing voltage Vc becomes equal to the value of the reference voltage V3, that is, when the position of the cam disk 18 at symbol f reaches the abutting position. The output of the arithmetic circuit 20 that drives M becomes 0 and stops.

Therefore, in the reproduction mode selection operation, the mute switch S1 is closed after the recording/reproducing head 2 contacts the magnetic tape, so that the transient reproduction sound at the time of contact can be cut.

It is understood that when the stop mode is selected from the reproduction mode, contrary to the above, the transient reproduction sound when the recording/reproducing head 2 leaves the magnetic tape is cut by the operation opposite to the above.

Next, when changing from the stop mode to the recording mode, the recording/playback changeover switch S4 is switched to the recording side R, and the playback switch SW3 is closed.

By closing the regeneration switch SW3, the control motor M drives the cam disk 18 counterclockwise and the variable terminal Tc in the direction toward the positive power supply +E in the same manner as described above.

For this purpose, the recording/reproducing head 2 first contacts the magnetic tape, and then, at the position d of the cam disk 18, the comparison circuit 27 outputs an output signal to operate the relay RL3 and close the bias switch S3 to bias the magnetic tape. Bias power supply Vc to circuit 38
c, followed by a comparator circuit 26 at the position of symbol e.
outputs an output signal to operate relays RL1 and RL2 and close mute switches S1 and S2.

When the position f of the cam disk 18 reaches the abutment position, the output of the arithmetic circuit 20 becomes O, the control motor M is stopped, and the recording mode is entered.

Therefore, in the recording mode selection operation, since the bias switch S3 and the mute switch S2 are closed after the recording/reproducing head 2 contacts the magnetic tape, troubles due to transient operations such as unnecessary magnetization at the time of contact are prevented.

On the other hand, when the recording mode is selected, it is understood that the above-mentioned trouble when the recording/reproducing head 2 separates from the magnetic tape can be prevented by performing the operation opposite to that described above.

Further, when the fast forward switch SW2 is closed from the stop mode, the cam disk 18 moves counterclockwise and the variable terminal Tc
are each driven in the direction toward the positive power supply +E, and when the position of the cam disc 18 reaches the position where it meets the rolling contact roller 15, the control motor M stops, but the value of the changing voltage Vc is the reference value. Since the voltage does not exceed the values of 4 and v5, the mute switch S1. S2 and bias switch S3 are not closed, and the lever 11 is not rotated from its position in the stop mode, so the head substrate 7 is in the retracted position.

Closing the fast-forward switch SW2 controls the drive circuit that rotates the reel stands 4, 4 at high speed.

In the above-mentioned embodiment, modes such as rewind and pause are omitted, but if a reference voltage is set for each of these modes and a desired cam shape is formed on the corresponding circumferential surface 19 of the cam disk 18, good.

Furthermore, in the above embodiment, the bias switch S3 and the mute switch S2 of the recording circuit are closed by the playback mode selection operation, and the mute switch S1 of the playback circuit is closed by the recording mode selection operation. This can be avoided by providing a switch means in a predetermined position that operates in conjunction with the playback switch SW3 or the recording/reproduction switch S4 so that the relays RL1 to RL3 and the switches S1 to S3 The control circuit may be formed using a transistor circuit.

Furthermore, in the embodiment, the variable voltage manually applied to the comparison circuits 26 and 27 is obtained by the rotary variable resistor VR associated with the control motor M, but the invention is not limited to this. Alternatively, a slit of a desired shape may be formed on the head substrate, and a light emitting element and a light receiving element are placed between the slits, and a change signal is generated based on the amount of received light that changes in response to the displacement of the head substrate. You can let me.

The comparator circuits 26 and 27 are not limited to producing an output when the variable voltage applied to the human power becomes greater than the reference voltage, but may each configure related components to produce an output when the varying voltage applied to the human power becomes smaller than the reference voltage. It is possible.

Furthermore, the comparison between the change signal and the reference signal in the comparison circuit is not limited to the voltage of these signals, but may also use frequencies or the like.

As described above, according to the present invention, it is possible to easily obtain a control device that prevents various transient inconveniences that occur when the head approaches and separates from the magnetic tape, and since the control is performed electrically. Since the operation is reliable and adjustment is easy, it has excellent operability and is extremely useful in practice.

[Brief explanation of the drawing]

The figure shows a mechanical part and a circuit diagram of an embodiment in which the device of the present invention is applied to a cassette recorder. 2... Recording/playback head, 7... Head board, 24...
Variable voltage generating means, 25...recording/playback circuit, 26.2
7... Comparison circuit, 28.29... First input, 30
．． 31...Second input, Vc...Variable voltage, V4.
V5...Reference voltage.

Claims (2)

[Scope of utility model registration request] (1) Variable voltage generating means that generates a continuous varying voltage in relation to the moving operation of the head board that moves from a stop position to a playback or recording operation position; A comparison circuit that applies a reference voltage and produces an output only when one of the first and second input levels is higher (or lower) than the other, and the output of the comparison circuit constitutes a playback or recording circuit. and a control circuit that operates a necessary electric circuit to perform the magnetic tape, and the comparison circuit controls the contact and separation between the head and the magnetic tape, which is formed between the stop position and the playback or recording operation position by the movement of the head substrate. A control device for a tape recorder, characterized in that the output is produced at a predetermined position closer to the playback or recording operation position. (2) The control device for a tape recorder according to claim 1, wherein the level of the reference voltage is continuously variable.