JPH02121147A - Tape drive controller - Google Patents

Abstract

PURPOSE:To drive a tape in consideration of the influence of the mechanical load produced between reels or the tape load by controlling a servo circuit so as to keep a constant level of the counter electromotive force that is produced when one of a pair of reel motors is driven by the other one. CONSTITUTION:A take-up side supply reel motor 1 is used together with a supply side reel motor 2, a servo circuit 3 which controls the drive of the motor 1, a detecting circuit 4, and a switch circuit 5 which connects with switch the circuit 4 to the motor 2 and the circuit 3 to the motor 1 in accordance with the tape traveling direction. In such a constitution, the motor 2 is revolved via a tape in response to the drive of the motor 1. In this case, the counter electromotive force, i.e., the torque is produced and detected by the circuit 4. Then the drive of the motor 1 is controlled so that the voltage and the torque are kept at a constant level respectively. Thus it is possible to reduce the influence of the mechanical load produced between both reels or the tape load.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tape drive control device for a tape recorder.

BACKGROUND ART For example, in digital tape recorders that record and play back audio signals using the PCM system, or video tape recorders that record and play back video and audio, fast forwarding, winding, so-called high-speed search, and picture search (
When performing high-speed tape running such as high-speed playback, the tape tension and tape speed are easily and reliably controlled to ensure high-speed search, etc., and to prevent uneven tape winding and tape damage. It is necessary.

Therefore, there have conventionally been devices using a tape drive control device for a tape recorder as disclosed in Japanese Patent Application Laid-Open No. 5E3-44141.

A conventional tape drive control device for a tape recorder will be described below.

FIG. 4 shows a conventional tape drive control device for a tape recorder. In FIG. 4, 41 and 42 are reel motors (DC motors) on the winding side and the supply side, respectively. A speed control signal for the reel motor 41 is applied to the input terminal 43 of the drive circuit 44. The speed control signal for the reel motor 41 may be of any type as long as it can keep the rotational torque of the reel motor 41 constant.
This conventional example shows a case where the reel motor 41 is driven at a constant voltage. On the other hand, during winding, the reel motor 42 on the supply side is reversely rotated by the reel motor 41 on the take-up side via a tape (not shown), and against this rotation, a back tension in the forward rotation direction is obtained. The conventional method is to supply the tensilon control signal from the drive circuit 45, but in this conventional example, a detection means for detecting the drive current of the supply side reel motor 41, such as a resistor 46, is further provided, and this resistor 46 is supplied to one input terminal of a voltage comparator 48 via a differential amplifier 47, and the voltage generated across the terminal 46 is supplied to one input terminal of a voltage comparator 48 through a differential amplifier 47 and a predetermined reference voltage supplied from an input terminal 49 to the other input. The supplied detection voltages are compared, and according to the magnitude of the difference voltage, the pack tension scene by the supply side reel motor 42 is controlled via the drive circuit 45, and the winding unit engages with the reel motor 42 via the tape. The configuration is such that the rotational torque of the side reel motor 41 is constant. That is, since the torque generated in the motor is proportional to the drive current of the motor, when the drive current of the reel motor 41 changes due to load fluctuations in the tape bus system, the resistor that detects the drive current of the reel motor 41 changes. 46 changes, and this changed terminal voltage is supplied as a detection voltage to a voltage comparator 48 via a differential amplifier 47 and compared with a reference voltage. The voltage comparator 48 is set in advance so that when the detected voltage is higher than the reference voltage, its output level becomes small (or becomes large in the opposite case).

Therefore, when the drive current of the reel motor 41 increases due to load fluctuation, its rotational torque also increases, but at this time, the output level of the voltage comparator 48 decreases as described above, so it depends on the output level of the voltage comparator 48. The torque in the forward rotation direction of the reel motor 42, which is energized via the drive circuit 45, ie, the pack tension, is also reduced. As a result, the torque of the reel motor 42, which is engaged with the reel motor 41 through the tape, becomes smaller, and its drive current also becomes smaller, so that a constant rotational torque is maintained, and the constant speed of the reel stand on the winding side is maintained. This allows the tape speed to be constant.

Problems to be Solved by the Invention However, in the conventional configuration described above, the signal for controlling the reel motor on the supply side is based on the signal that detects the drive current of the reel motor on the winding side. There was a problem in that the effects of the mechanical load, tape load, and tape path were not fully taken into consideration.There was also a problem in that two motor drive circuits were required.

The present invention solves the above-mentioned conventional problems.The present invention detects the state of the reel motor on the supply side and controls the drive of the reel motor on the take-up side based on the detected output. It is an object of the present invention to provide a tape drive control device which can control tape drive in consideration of the influence of tape load and which can be implemented with a single motor drive circuit.

Means for Solving the Problems The present invention provides a first
．． a second pair of reel motors, a detection means for detecting a reverse induced voltage generated in the other reel motor rotating when one of the reel motors is driven, and a reverse induced voltage obtained from the other reel motor; A servo circuit that drives the one reel motor so that the voltage is constant, and a first servo circuit that drives the output of the detection means and the output of the servo circuit according to the tape running direction. a second reel motor or a second reel motor; The reel motor is characterized by comprising a switching means for switching to the first reel motor.

Operation According to the present invention, by driving the first reel motor, the other reel motor rotates in conjunction with the tape. The reverse induced voltage, that is, the torque generated at this time is detected by the detection means. The first reel motor is then controlled so that the detected voltage and torque are constant. Similar control is performed by switching these reel motors by the switching means. In this way, the influence of mechanical load and tape load occurring between both reels can be reduced.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a tape drive control device in one embodiment of the present invention. 1 is a supply reel motor on the winding side; 2 is a supply reel motor; 3 is a servo circuit that drives and controls the reel motor 1 on the winding side; 4 is a circuit that detects a reverse induced voltage generated when the reel motor 2 on the supply side rotates. A detection circuit 5 is a switching circuit that switches the connection of the detection circuit 4 to the supply reel motor and the servo circuit 3 to the take-up reel motor depending on the tape running direction.

FIG. 2 is an equalization circuit diagram of the reel motor. FIG. 3 is a block diagram showing the servo circuit 3. In the figure, the voltage output obtained from the detection circuit 4 is given to a voltage comparator 32 via a voltage amplifier 31. A speed control signal is given to the voltage comparator 32, and the output of the current amplifier 33 is controlled so that these voltages are constant. The output of the current amplifier 33 is then given to the reel motor 1 or 2 via the switching circuit 5 as a motor drive output.

Next, the operation of the tape drive control device of this embodiment will be described. In this embodiment, the reel motors 1 and 2 are DC motors, and the servo circuit 3 generates a torque in the reel motor that is proportional to the input speed command voltage, and here it is assumed that the motor is driven by current. . Now, an explanation will be given taking as an example a case where the tape is run at high speed in one direction, such as in fast forwarding. When the tape running mode is commanded, the switching circuit 5 connects the servo circuit 3 to the take-up reel mode 1 and the detection circuit 4 to the supply reel motor 2 according to the tape running direction, as shown in FIG. Next, a predetermined speed control signal is input to the servo circuit 3. The servo circuit 3 drives the take-up reel motor 1 with current so that a torque proportional to this speed control signal is generated. By the way, the torque generated in a DC motor is proportional to the current flowing through the motor. That is, if the generated torque is T1, the current flowing through the motor is 11, and the torque constant of the motor is Kt, then the following equation holds true.

T=K t @I...
- (1) Therefore, the take-up side reel motor 1 starts rotating with constant torque. This causes the tape to run in one direction.

Therefore, the supply reel motor 2 is forcibly rotated in the same rotational direction as the take-up reel motor 1 as the tape runs. The supply reel motor 2 generates a reverse induced voltage by rotating. Here, the voltage applied to the motor is Esv, the resistance of the motor coil is Ra1, the current flowing through the motor is E, and the reverse induced voltage generated in the motor is E.
When a is used, the following equation holds true from the equalization circuit shown in FIG.

Es=Ra@I'' (2) By the way, since the supply side reel motor 2 is not driven from the outside, the following equation holds true.

Ea=RaII-(3) Therefore, from equations (1) and (3), the torque T2 generated in the supply side reel motor 2 is as shown in the following equation.

In other words, the torque generated in the supply side reel motor 2 is proportional to the reverse induced voltage generated in the reel motor 2. Furthermore, if the power generation constant of the motor is Ka, and the rotational speed of the motor is N, then the reverse induced voltage can be expressed as follows.

Ea=Ka11N-(5) Therefore, by configuring the servo circuit 3 as shown in FIG. 3, the reel stand can be rotated at a constant speed. That is, the reverse induced voltage of the supply side reel motor 2 detected by the detection circuit 4 is amplified by the voltage amplifier 31 to a predetermined voltage.

A voltage comparator 32 compares this amplified signal with a speed command signal input to the servo circuit 3. This voltage comparator 3
2 is such that when the speed command signal is larger than the output of the voltage amplifier 31, the current flowing to the reel motor 1 is increased, and when the two are equal, the current is maintained when the two are equal; If it is smaller, a torque command voltage is applied to the current amplifier 33 so as to cause the current to flow through the reel motor 1 so as to reduce the current. The current amplifier 33 drives the reel motor 1 with current according to the torque command voltage that is the output of the voltage comparator 32. As described above, the take-up reel motor 1 is driven and controlled so that the reverse induced voltage generated in the supply reel motor 2 is constant. That is, as can be seen from equation (5), the drive control is performed so that the rotational speed N of the reel motor 2 is constant.

Effects of the Invention As described above, the present invention rotates the other reel motor by driving one of a pair of reel motors, and by controlling the servo circuit so that the reverse induced voltage generated at that time is constant, The reel motor can be controlled to be driven a constant number of times, that is, at a constant speed, regardless of the influence of a mechanical load such as a reel stand, a tape load, etc. moreover,
By switching the detection means and the servo circuit using the switching means according to the running direction of the tape, it is possible to drive the reel motor at a constant speed in both the forward and reverse directions of the tape using one set of the servo circuit and the detection means, thereby reducing costs. You can get the effect of

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a tape drive control device according to an embodiment of the present invention, FIG. 2 is an equalization circuit diagram of a reel motor, and FIG. 3 is a servo circuit in FIG. 1. 1... Winding side reel motor, reel motor, 3... Servo circuit, 5... Switching circuit.

Claims (1)

[Claims] Detecting a reverse induced voltage generated in a pair of first and second reel motors configured to be interlocked via a tape and the other reel motor rotating when one of the reel motors is driven. a detection means, a servo circuit for driving the one reel motor so that the reverse dielectric voltage obtained from the other reel motor is constant, and an output of the detection means and the servo circuit according to the running direction of the tape. 1. A tape drive control device comprising switching means for switching outputs of the reel motors to the first and second reel motors or the second and first reel motors, respectively.