JPS5810184Y2 - Fast forward/rewind muting circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fast forward/rewind muting circuit in a magnetic recording/reproducing machine.

The applicant has already proposed a tape drive control circuit in a tape drive control device for a magnetic recording/reproducing machine, which is configured to control switching between constant speed forwarding, fast forwarding, and rewinding of the tape by operating a single changeover switch. ing.

The present invention provides such a fast-forwarding/rewinding device, in which the changeover switch maintains the constant-speed control circuit even in the circuit switching process from constant-speed forwarding to fast-forwarding and rewinding. In addition to preventing tape noise during the fast-forward/rewind switching process, the amplifier circuit is grounded and muted during the fast-forward/rewind switching process to prevent motor noise and tape noise picked up through the amplifier. It is characterized by reliable prevention.

In other words, the conventional tape noise phenomenon occurs because the tape drive motor separates from the constant speed control circuit immediately after switching between fast forward and rewind.
Immediately after switching, the motor may be caused by forced rapid driving while the tape is temporarily held between the campstan and pinch roller, or vibrations caused when the tape is instantaneously switched to rapid running or rapid driving itself. This is due to the fact that the tape vibrations generated by the tape are picked up as input to the amplifier.

Therefore, as mentioned above, the present invention maintains the constant speed of the tape even during the rewind/fast forward switching process, and also uses amplifier muting to prevent the generation of various noises including tape rumble and motor noise. This is to ensure muting.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a tape drive control circuit for a magnetic recording/reproducing machine capable of implementing a fast-forward/rewind muting circuit according to the present invention.

In the figure, SW2 is a tape end detection switch, and a fixed terminal of the tape end detection switch SW2 is connected to a trigger circuit A.

This trigger circuit A is the tape end detection switch SW2.
It has the function of outputting a trigger signal to instruct a certain operation to a motor control circuit, etc., which will be described later, in response to the tape end detection signal, and for example, a retrigger type one-shot multivibrator circuit is used.

A tape reversal command circuit C is connected to this L rigger circuit A, and the tape reversal command circuit C is connected to a tape drive motor M.
Further, signals from the motor constant speed drive control circuit E are applied to the motor M through the motor forward and reverse drive control circuit.

The tape forward/reverse drive control circuit has the function of converting the flow of current flowing through the tape drive motor and causing the motor to rotate forward or reverse depending on the direction of the current flow.

Further, the output polarity of the tape reversal command circuit C is reversed at the same time as the trigger signal is applied by the trigger signal of the trigger circuit A, and the tape is driven forward or backward depending on the signal polarity, for example, whether it is a ←) signal or a (←) signal. The control circuit is operated to change the direction of the current flowing through the tape drive motor M to reverse rotation, thereby rotating the tape from the forward direction to the reverse direction or from the reverse direction to the forward direction.

That is, a reverse operation of the tape is obtained. This operation is automatically performed each time the end of the tape is detected by the switch SW2.

Like the tape reversal command circuit C, the output polarity is reversed each time a trigger is applied, and a T-type flip-flop circuit is used as a circuit for controlling forward/reverse drive of the tape drive motor M in accordance with the polarity.

The output of the T-type flip-flop circuit is connected to the head switching circuit G.
is also applied, and depending on the output polarity, the scanning channel of the head is also switched at the same time as the above-mentioned tape reversal operation.

Incidentally, SW3 is a manual switch for the purpose of manually obtaining a tape reverse signal by performing a series of operations by the tape end detection switch SW2 to detect the end of the tape.

As mentioned above, the motor constant speed drive control circuit E is connected to the motor forward/reverse drive control circuit, and the constant speed control generator FG normally functions to drive the tape drive motor M at a constant speed. Controls constant speed feeding of the tape.

The motor constant speed drive control circuit E is provided with a constant speed feed, fast forward, and rewind changeover switch SW1 for controlling the operation and non-operation of the motor constant speed drive control circuit E.

The fast forward/rewind changeover switch SW1 has a switching ground contact S, a constant speed feed contact C1, a fast forward contact a, and a rewind contact S, and is normally connected to the operating contact C of the motor constant speed control circuit E to maintain constant speed. The control generator FG is operated, and the circuit A,
The constant speed running of the tape is controlled in the direction according to the commands C and D, and the constant speed control generator F of the motor constant speed control circuit E is controlled by switching the movable contact S to the contact a or b.
G is separated 1-The configuration is such that fast forwarding and rewinding of the tape is obtained.

That is, the movable contact S of the fast forward/rewind switch SW1
When connected to fast-forward contact a, the motor constant speed control circuit E is disconnected, the constant speed control generator FG of the circuit E stops functioning, and the motor M is driven in a certain direction by the operation of the motor forward/reverse drive control circuit. A current is applied to drive it rapidly.

In other words, the tape is fast forwarded. Also, when the movable contact S of the fast forward/rewind switch SW1 is connected to the rewind contact S, the constant speed control generator F of the motor constant speed drive control circuit E is connected.
G is disconnected, and the motor forward/reverse drive control circuit operates to flow a current in the opposite direction to the tape drive motor M to rapidly drive it in the opposite direction.

That is, the tape is rewound.

Motor forward/reverse drive circuit fast forward/rewind switch S
By simply switching W], it is disconnected from the motor constant speed drive control circuit E, and by disabling the constant speed control generator FG, rapid drive is possible, and the motor M in the motor forward/reverse drive circuit is disconnected. Switching from constant speed drive to fast forwarding and rewinding is solved with an extremely simple circuit configuration due to the current conversion action of the switch.
By selecting L'''O, each of the above operations can be reliably achieved, the number of contacts is minimal, the structure is simple, and the failure rate is extremely low. In a fast-forward/rewind device in a magnetic recording/reproducing machine configured so that switching to reverse is performed by a single changeover switch mechanism, the changeover switch SW1 switches ground contact S to constant-speed forward contact C, or fast-forward or rewind. Even in the process of switching the circuit to the return contacts a and b, without immediately disconnecting the motor constant speed drive control circuit E,
The configuration is such that the function of the constant speed control generator FG is maintained by maintaining contact with the contact point C, and as shown in the figure, fast forwarding,
A current backflow prevention diode D1 is provided at each of the rewinding switching contacts a and b. An amplifier (Amp) circuit is connected through D2, and in the process of switching the ground contact S, it maintains contact with the constant speed feed contact C and at the same time makes contact with the fast forward or rewind contact a or b, Therefore, the configuration is such that the amplifier (Amp) circuit is grounded (muted) via the ground contact S.

R is a resistor for preventing complete discharge of the capacitor built in the amplifier (Amp), and prevents noise caused by charging the capacitor when the switch SW1 is released.

D3. D4 is a diode that prevents a DC component from flowing back into the motor forward/reverse drive circuit, thereby protecting the circuit and preventing malfunction.

FIGS. 2 and 3 show an embodiment of a switch mechanism that achieves the operation described above.

As shown in the figure, the rapid forward contact a, the rewind contact S, and the constant speed forward contact C are mounted and supported on a base 2 in an insulating case 1 by elastic contact pieces 3a, 3b, and 3c, respectively, and a switching ground contact S is composed of movable contacts S1 and 82, and is similarly mounted and supported on the base 2 by elastic contact pieces 3S and 382, both of which are connected to elastic contact pieces 3S1 and 382.
The movable contacts S1 and 82 of the ground contact S are configured to constantly contact the constant speed feed contact C due to the elasticity of S2, and the movable contacts S1 and 82 of the ground contact S have switching pieces 3S3 and 3S4 protruding from elastic pieces as shown in the figure. A switch 4 is interposed between and 384 so as to be swingable about the shaft 5.

On the other hand, a switching operation lever 6, which works in conjunction with a head mounting board (not shown) and also operates the pinch roller and the campstan from contact to separation, is mounted and supported so as to be rotatable about a shaft 7. Center holding spring 8 attached to 6
grips the free end of the switch 4, and its elasticity holds the center.

In the free state where the ground contact S and the constant speed feed contact C are in contact, the play between the hent electric board and the operating lever 6 is taken into consideration, and even if the lever 6 is rotated, the constant speed feed contact C is immediately turned off. A constant clearance is set without turning on the fast forward or rewind contacts a and b.

Thus, the switching element 4 has sensing parts 4a s 4b t4c
, 4d, and its operation will be explained based on FIG. 3. Let us now assume that the center is held as shown in FIG. When the operating lever 6 is rotated toward the fast-forward contact a side when the constant speed control generator FG of the circuit E is functioning, the switching element 4 swings and the switching element 4 is rotated with a certain clearance.
The switching piece 3 of the movable contact S whose sensing part 4a is the earth contact S
Press S3 in the direction of the fast-forward contact a to bring the movable contact S1 into contact with the fast-forward contact a, resulting in the state shown in FIG. 3B.

As a result, the amplifier (Amp) circuit is muted via the ground contact S, and at the same time, in this state, the constant speed feed contact C and the other movable contact S2 are kept in the on state, and the motor constant speed drive control circuit The constant speed control generator FG at E functions, and the tape drive motor M continues to drive at a constant speed, and by turning on the fast forward contact a and the movable contact S, only the tape running direction is fed at a constant speed in the fast forward direction. .

In this way, during the fast forward/rewind switching process, the state shown in Fig. 3B is reached, and constant speed tape feeding is maintained, and the amplifier circuit is muted to eliminate tape noise, motor noise, etc. caused by fast forwarding. Various noises are amplifiers (Amp)
It is reliably prevented from being picked up by the user and causing unpleasant noise.

Furthermore, when the operating lever 6 is rotated from the state shown in FIG. 3B to the stop position and the switch 4 is further swung in the same direction, the switch 4
The sensing portion 4a of the ground contact S brings the movable contact S1 of the ground contact S into even stronger pressing contact with the fast-forward contact a, and the sensing portion 4d of the switching element 4 presses the other movable contact S2 of the ground contact S in the direction of making the rewind contact. , the state shown in FIG. 3C is reached, in which the contact with the constant speed feed contact C is released.

As a result, the muting of the amplifier (Amp) circuit continues through the rapid feed contact a and the ground contact S, and the constant speed feed contact C is turned off, disconnecting the motor constant speed drive control circuit E and controlling the constant speed. Since the control by the generator FG is released, the tape is fast-forwarded for the first time at this point.

Since muting of the amplifier circuit continues even during the fast forwarding, motor noise, tape ringing, etc. are reliably prevented.

The above operation has been explained for switching from constant speed forwarding to fast forwarding, but in the case of constant speed forwarding and rewinding switching, the sensing parts 4b and 4c of the switching element 4 are connected to the movable contact S1 of the ground contact S.
, S2, the same effects as described above can be obtained.

According to the circuit configuration of the present invention, as mentioned above, switching from constant speed tape feeding to rapid tape feeding (fast forwarding, rewinding) can be performed with a single changeover switch, and the switching mechanism is significantly simplified and trouble-free. There is an advantage that the rate is extremely small, and by selecting the contacts a, b, and c of the switch SW1, each of the above-mentioned constant-speed forwarding, fast-forwarding, and rewinding operations can be reliably obtained.

The present invention utilizes a fast-forward/rewind device configured to switch from constant-speed tape feeding to fast-forwarding and rewinding using a single switch mechanism, and the changeover switch SW1 connects the ground contact S to the constant-speed feed contact. C fast forward or rewind contact a
, b, the motor constant speed drive control circuit E is not immediately disconnected, but maintains contact with the contact point C to maintain the function of the motor constant speed drive control circuit E. At the same time, an amplifier circuit is connected to each of the fast forward and rewind switching contacts a and b, so that during the switching process of the ground contact S, the contact with the constant speed feed contact C is maintained and the fast forward or rewind is simultaneously performed. Since the configuration is designed to make contact with contact a or b and thereby ground (muting) the amplifier Amp circuit via ground contact S, there is no tape noise during the process of switching from constant speed forwarding to fast forwarding or rewinding. , motor noise, etc. are effectively and reliably prevented, thereby preventing discomfort from being caused to the user.

In addition, the amplifier etc. are protected and equipment breakdowns are effectively prevented.

In addition, as mentioned above, this muting circuit can obtain the above-mentioned muting effect with an extremely simple circuit configuration by adding a simple switch means. It has remarkable characteristics such as never becoming.

Regarding the specific structure of the switch SW1, for example, a slide type switch or the like may be used.

[Brief explanation of the drawing]

FIG. 1 is a tape drive control circuit diagram of a magnetic recording/reproducing machine in which the present invention can be implemented, FIG. 2 is a plan view showing a specific example of a fast-forward/rewind switch, and FIGS. 3A and 3B. C is a plan view illustrating the operating state of the switching switch.

Claims (1)

[Scope of utility model registration request] A motor constant speed drive control circuit that controls the tape drive motor at a constant speed, a motor forward/reverse drive control circuit that controls the forward/reverse drive of the tape drive motor, and a motor forward/reverse drive control circuit that switches the tape from constant speed forwarding to fast forwarding and rewinding. The changeover switch means includes a constant speed feed contact connected to the motor constant speed drive control circuit, and a fast forward contact and a rewind contact connected in parallel to the motor forward/reverse drive control circuit. , is selectively connected to the constant speed feed contact to operate the motor constant speed drive control circuit to feed the tape at a constant speed, and is selectively connected to the fast forward contact and the rewind contact to operate the motor constant speed drive control circuit. and a switching ground contact for disconnecting the motor and operating the motor forward/reverse drive control circuit to fast-forward or rewind the tape, and the change-over switch means for switching from the constant-speed feed contact to the fast-forward contact and the rewind contact. In the switching process, the switching mechanism connects to the fast-forwarding contact or the rewinding contact while maintaining the connection with the constant-speed feeding contact, and disconnects the constant-speed feeding contact after the switching connection to the fast-forwarding contact or the rewinding contact. At the same time, an amplifier circuit is connected to each of the fast forward contact and the rewind contact, and the amplifier circuit is connected to the fast forward contact or the rewind contact and the earth contact under the connection of the constant speed forward contact and the ground contact in the switching process. A fast forward/rewind muting circuit characterized by having a grounded configuration.