JPH0574139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus using a tape-shaped recording medium such as a video tape recorder.

Configuration of a conventional example and its problems Hereinafter, a conventional magnetic recording/reproducing device will be described with reference to the drawings. FIG. 1 is a circuit diagram of a control system of a reel drive motor in a conventional magnetic recording and reproducing apparatus. In the same division, 1 is a magnetic tape, 2 is a supply reel, 3 is a take-up reel, 4 is a tape speed detection roller with an extremely small inertial force that rotates in response to the running force of the magnetic tape 1, and 5 is a tape speed detection roller 4 A rotary encoder is attached to the rotating shaft of the rotary encoder and has notches or shading at equal intervals on its circumference, 6 is a photo interrupter for obtaining pulse signals from the rotating rotary encoder 5, and 7
is a reel motor that drives the take-up reel 3.

Now, in FIG. 1, in the FWD mode in which the magnetic tape (hereinafter simply referred to as tape) 1 runs in the forward direction, the tape 1 passes from the supply reel 2, to the head device (not shown), to the cylinder 9, and then to the tape. It passes through a speed detection roller 4 and is wound onto a take-up reel 3. At this time, the running speed of the tape 1 is determined by the tape speed detection roller 4 whose rotational speed changes in proportion to the running speed of the tape 1.
By the rotation of a rotary encoder 5 attached to the rotary encoder 5, the frequency of a pulse signal obtained from a photointerrupter 6 consisting of a light emitting element and a light receiving element is detected. Waveform shaping circuit 1 for the pulse signal
0 to the speed control circuit 10 as a speed detection signal i, and the error signal a is sent to the switch 21.
(In the FWD mode, the switch 21 is closed to the contact d side) and is supplied to the motor drive circuit 12.
The motor drive circuit 12 is composed of a voltage-current conversion circuit, and drives the reel motor 7 with a current I1 (I ₁ =V1/R) corresponding to the voltage V1 of the error signal a, thereby adjusting the tape speed. control to keep it constant. The (+) terminal of the reel motor 7 is connected to the power supply voltage _Vcc , and the (-) terminal is connected to the motor drive circuit 12. The tension sensor 15 converts the amount of movement of the tension lever 14, which is proportional to the magnitude of the tension on the tape, into an electrical signal b using a photo interrupter and a light shielding plate attached to the tension lever 14. It is. This electrical signal b is applied to the tension control circuit 16,
The control signal c is supplied to the motor drive circuit 13 via the switch 20 (in the FWD mode, the switch 20 is closed to the contact f side). The motor drive circuit 13 has the same configuration as the motor drive circuit 12, and has a current I2 (I2=V
2/R) and is supplied to the reel motor 8. The reel motor 8 is controlled by this current I2 to keep the tension of the tape constant. The (+) terminal of the reel motor 8 is the power supply voltage V _cc
In addition, the (-) terminal is connected to the drive circuit 13.

When switching from the high-speed reproduction mode to the stop mode, the switch 21 closes to the contact e side, and the reel motor 7, like the reel motor 8, switches to tension control that keeps the tension of the tape constant. The amount of movement of the tension lever 17 that is proportional to the tape tension at the entrance of the take-up reel 3 is converted into an electric signal j by a tension sensor 18 and supplied to a tension control circuit 19. The control signal k is supplied to the motor drive circuit 12 through the switch 21, converted into a current according to the voltage of the control signal k, and controls the reel motor 7. That is, at the same time as switching from the high-speed reproduction mode to the stop mode, the reel motors 6 and 7 are both under tension control, and are stopped due to the tension balance between the supply side and the winding side. However, even if you switch to tape, it will continue to run for a while due to inertia during high-speed playback. Therefore, conventionally, by changing the switch 22, the reel drive motor 7 on the tape supply side is controlled in the rotational direction (CW).
The brakes are applied by increasing the rotational torque (CCW) in the opposite direction. At the same time as switching from the high-speed regeneration mode to the stop mode, the switch 22 closes to the contact m side, and the motor drive circuit 13 is connected to the voltage dividing resistor 2.
3 is supplied as an input voltage. Since the voltage V4 is larger than the voltage V2 of the control signal c, the current I4 flowing through the reel drive motor 8 at this time is the current I before mode switching.
It is larger than 2. The rotational torque of the motor is proportional to the motor current, so when switching from high-speed playback mode to stop mode, the counterclockwise (CCW) rotational torque of the reel motor 8 increases, and the tape continues to run due to inertia. is being prevented.

However, with this conventional method, in order to stop the tape running in a short time, it is necessary to rotate the tape in the counterclockwise direction (CCW).
It is necessary to apply a large rotational torque to the tape, which places an abnormal tension on the tape and causes damage to the tape. Therefore, if the rotational torque in the opposite direction is reduced, the damage to the tape is reduced, but the time required for stopping becomes longer. Therefore, the conventional braking system has a problem in that it is impossible to stop the tape in a short time and without applying an impact.

OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetic recording/reproducing device that can stop a tape running at high speed instantaneously and without applying an impact.

Structure of the Invention The magnetic recording and reproducing apparatus of the present invention includes a first reel drive motor that rotates a tape take-up reel, a second drive motor that rotates a tape supply reel, and a tape supply reel that is supplied by the first reel drive motor. a speed control means for controlling the speed of the tape wound from the reel onto the take-up reel; a tension control means for controlling the tension of the tape fed from the supply reel by the second reel drive motor; When stopping the first reel drive motor and the second reel drive motor, the short-circuit current that flows when the first reel drive motor and the second reel drive motor are short-circuited is used to reduce the rotational torque of the take-up reel in the winding direction, and also to reduce the rotational torque of the take-up reel in the winding direction. The present invention includes a brake means for applying a brake by increasing rotational torque in a direction opposite to the tape feeding direction.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows a circuit diagram of a control system for a reel drive motor in one embodiment of the present invention. In the figure, numerals 1 to 21 are the same as those in FIG. 1, so the explanation here will be omitted. The (-) terminals of the reel motors 7 and 8 are connected via a resistor 25 and a switch 24. 26 is an input terminal for a stop mode command signal, and the switch 24 is controlled on/off by the stop mode command signal h. switch 24
operates so that it is in the on state in stop mode and in the off state in other modes. Therefore, at the same time as the high-speed reproduction mode is switched to the stop mode, the switch 24 is turned on, and the (-) terminal of the reel drive motor 7 and the (-) terminal of the reel drive motor 8 are short-circuited via the resistor 25.

As mentioned above, in the high-speed reproduction mode, the switch 26 is turned off, so the reel drive motor 7 receives a current I1 corresponding to the voltage V1 of the error signal a.
(=V1/R) flows, and the reel motor 8 receives a current I2 (=V2/R) corresponding to the voltage V2 of the control signal c.
R) flows. At this time, since the rotational torque direction of the reel drive motor 8 is different from the actual rotational direction (brake operation), the voltage at the (-) terminal becomes higher than the power supply voltage _Vcc . Since the rotational torque direction of the reel drive motor 7 is the same as the actual rotational direction (motor operation), the (-) terminal has a voltage lower than the power supply voltage _Vcc . When changing from the high-speed regeneration mode to the stop mode, the switch 21 closes to the contact e side and the switch 24 turns on, so the motor drive circuit 12 receives a current I3 (=V3/R) according to the voltage V3 of the control signal k. flows, and a current I4 flows from the (-) terminal of the reel drive motor 8 to the (-) terminal of the reel drive motor 7 via the resistor 25. Current I flowing through motor drive circuits 12 and 13
The current I4 flowing through the resistor 25 is independent of the currents I3 and I2 of the drive circuits 12 and 13, since the currents I3 and I2 are determined only by the respective input voltages V3 and V2. Due to this current I4, the current of the reel drive motor 7 becomes I3-I4, and the current of the reel drive motor 8 becomes I2+I4. In other words, the current flowing through the reel drive motor 7 decreases (I3
→I3→I4), the clockwise (CW) rotational torque of the reel drive motor 7 decreases (the rotational torque of the motor is proportional to the motor current), and the current flowing through the reel drive motor 8 increases (I2→ I
2→14), the rotational torque of the reel motor 8 in the counterclockwise direction (CCW) increases. Therefore, when switching from high-speed playback mode to stop mode, the reel drive motor 7 is prevented from continuing to rotate in the clockwise direction (CW) and the reel drive motor 8 is prevented from continuing to rotate in the counterclockwise direction (CCW) due to inertia force. For,
By short-circuiting the (-) terminals of the reel drive motors 7 and 8 via the resistor 23, the rotational torque of the reel drive motor 8 in the counterclockwise direction (CCW) increases rapidly, and the reel drive motor 7 rotates clockwise. The rotational torque in the CW direction suddenly decreases, and the tape stops running instantly. Moreover, since the temporal change in the rotational torque in the reel drive motor 8 and the temporal change in the rotational torque in the reel drive motor 7 are the same, there is little shock at the time of stopping. This is because the power supply _Vcc , reel drive motor 8, resistor 25, switch 24, and reel drive motor 7 form a closed loop. Reel drive motor 8
The voltage at the (-) terminal of the motor is the supply voltage V _cc in the clockwise direction (CW), ignoring the armature resistance inside the motor.
higher and in counterclockwise direction (CCW) V _cc
becomes lower.

On the other hand, if the armature resistance within the motor is ignored, the voltage at the (-) terminal of the reel drive motor 7 is lower than the power supply voltage V _cc in the clockwise direction, and higher than V _cc in the counterclockwise direction. Further, the potential difference between the power supply voltage V _cc and the voltage at the (-) terminal is proportional to the motor rotation speed. Therefore, when switching from high-speed playback mode to stop mode, current I4 flowing through resistor 25
is not always constant, and the reel drive motors 7 and 8
decreases as the rotational speed decreases. When the reel drive motors 7 and 8 completely stop, the potential difference between the (-) terminals of the reel motors 7 and 8 disappears (both become equal to the power supply voltage _Vcc ), so
Current I4 stops flowing. That is, there is no problem even if the switch 24 remains on after the tape stops.

When switching from the high-speed playback mode of the REW mode in which the tape runs in the reverse direction to the stop mode, the above operation is reversed.

As described above, according to the present invention, regardless of the running direction of the tape, when switching from high-speed playback mode to stop mode, the current flows through the closed loop created by the reel drive motors 6 and 7, the resistor 25, and the power supply voltage _Vcc . The loop current causes the supply side motor (FWD
In the reel drive motor 8 in the FWD mode, reel drive motor 7 in the REW mode), the rotational torque in the opposite direction to the tape running direction increases, and the rotational torque of the take-up side motor (reel drive motor 7 in the FWD mode, reel drive motor 8 in the REW mode) increases. ), the rotational torque in the same direction as the tape running direction is reduced, so the tape running stops instantaneously and without impacting the tape.

Effects of the Invention As is clear from the above description, the present invention includes a first motor that rotates a take-up reel, a second motor that rotates a tape supply reel, and a second motor that rotates a tape supply reel.
a first drive circuit that controls a battery of the motor; a second drive circuit that controls a battery of the second motor; and a second drive circuit that controls the battery of the second motor; The current flowing when the terminal connected to the circuit is short-circuited is used to reduce the rotational torque of the take-up reel in the winding direction, and to reduce the rotational torque of the supply reel in the opposite direction to the tape feeding direction. Since the structure includes a braking means that applies the brake by increasing the number of brakes, it has the excellent effect of being able to stop the tape running at high speed instantly and without applying a shock. It will be done.
As a result, for example, efficiency in editing work can be improved, and damage to the tape can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a control system for a reel drive motor in a conventional magnetic recording and reproducing apparatus, and FIG. 2 is a circuit diagram of a control system for a reel drive motor in an embodiment of the present invention. 1...magnetic tape, 2...supply reel, 3...
Take-up reel, 4...Tape speed detection roller, 5
... Rotary encoder, 6 ... Photo interrupter, 7, 8 ... Reel drive motor, 9 ... Cylinder, 10 ... Waveform shaping circuit, 11 ... Speed control circuit, 12, 13 ... Motor drive circuit, 14 ...
...Tension lever, 15, 18...Tension sensor, 16, 19...Tension control circuit, 1
7...Tension lever, 20-22, 24...
Switch, 25...Resistor, 26...Input terminal for stop mode command signal.

Claims (1)

[Claims] 1. A first motor that rotates a tape take-up reel, a second motor that rotates a tape supply reel, a first drive circuit that controls the current of the first motor, and a current of the second motor. a second drive circuit that controls a terminal of the first tape connected to the first drive circuit and the second drive circuit of the second motor when stopping the tape running; The current flowing when the terminal connected to the circuit is short-circuited is used to reduce the rotational torque of the take-up reel in the winding direction, and to reduce the rotational torque of the supply reel in the opposite direction to the tape feeding direction. A magnetic recording/reproducing device having a brake means that applies a brake by increasing the number of brakes.