JPS5870450A - Slanting scanning type magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To set the tension of a tape within a desired range, by detecting that tension of the tape has exceeded a prescribed value, by a capstan motor current, and moving an operating point of a feed side tension arm by this detecting signal. CONSTITUTION:A current detecting resistance 8, a current detector 9, an analog switch 10, a voltage generating circuit 11 and a voltage adder 18 are added to a circuit of a capstan motor 6. When the tension of a tape increases and a load of the capstan motor 6 increases, voltage across the resistance 8 becomes high. When this voltage exceeds a prescribed value, the analog switch 10 is turned on by an output of the current detector 9, and voltage from the voltage generating circuit 11, and reference voltage 12 are added by the voltage adder 18. As a result, supply voltage of a feeding reel motor 16 becomes high and an operating point of a tension arm 19 moves to a position where the tension of the tape becomes small, therefore, the tension of the tape of a head ram center part 20 drops and can be set within a desired range.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oblique scanning magnetic recording/reproducing device (hereinafter referred to as a VTR), and particularly to a VTR in which tape tension in a head drum section is controlled by changing the position of a supply side tension arm. It is.

In a VTR, a tape tension value at the center of the outer periphery of the head tram is specified in order to maintain mutual correlation between tapes. For example, in the case of a 1-inch VTR of SMPTE Type C format, the tape tension at the center of the head drum during recording and reproduction is specified to be 150±20 g. In order to protect this, conventionally, the applied tape tension was kept constant by keeping the position, or operating point, of the supply side tension arm constant.

As a result, the tape tension at the center of the head drum was controlled to a specified value. However, between the supply side tension arm and the center of the head drum, there is frictional resistance due to the fixed guide and the drum section, and this changes significantly depending on humidity, so even if the operating point of the supply side tension arm is controlled to be constant, It was extremely difficult to keep the tape tension at the center of the head drum within the specified range. And this one in particular.

There was a problem in that the tape tension at the center of the head drum became excessive during high humidity.

In order to eliminate these drawbacks, the present invention detects when the tape tension exceeds a predetermined value based on the current flowing through the capstan motor, and moves the operating point of the supply side tension arm based on this detection signal. The tape tension at the center of the outer periphery of the head drum is kept within a desired range.

Hereinafter, practical examples according to the present invention will be explained with reference to the drawings. In the control system of the capstan motor, a signal from the error voltage amplifier 3 is applied to the motor drive amplifier 4, which causes the capstan motor G to rotate, and a detection signal from the rotation detector 7 is applied to the phase comparator 2 and the circumferential rotation. The output signal of the phase comparator 2, which is applied to the detector 5 and compared with the reference signal ■, and the output signal of the frequency discriminator 5 are added together and applied to the error voltage amplifier 3, which drives the capstan motor 6 to a predetermined level. control to the state. In the control system of the supply reel motor, a reference voltage 12 is applied to a motor drive amplifier 15 via a tape tension detector 13 and an error voltage amplifier 14, which rotates the supply reel motor 16 and changes the position of the tension arm 19. A signal from the helipot 17 that detects the tension is applied to the tape tension detector 13, and the tension arm 19 is held at a predetermined position 19a to control the tape to a predetermined tension. Further, a current detection resistor 8, a current detector 9, an analog switch 10, a voltage generating circuit 11, and a voltage adder 18, which are inserted into the current circuit of the capstan motor 6, are additional control circuits according to the present invention.

Here, when the humidity increases, the tape tension increases, and the load on the capstan motor 6 increases, the current flowing through the resistor g increases, and the voltage across the resistor 8 increases. When this voltage exceeds a predetermined value, the analog switch 10 is turned on by the output signal of the current detector 9, and the voltage from the voltage generating circuit 11 and the reference voltage 12 are added together by the voltage adder 18. As a result, the supply voltage of the supply reel motor 16 increases, and the operating point of the tension arm 19 moves from 19a to 19b, where the applied tape tension is reduced, so that the tape tension at the head drum central portion 20 decreases.
It can be kept within a desired range.

In the figure, 24 is a capstan, 25 is a pinch roller, 26 is a supply reel, and 27 is a take-up reel.

As explained above, according to the present invention, the humidity increases,
Even if the frictional resistance between the tape, the fixed guide, and the head drum increases, the tape tension at the center of the head drum can be kept within a predetermined range.

[Brief explanation of the drawing]

The figure is a block diagram of a tape running system and a motor control system of a diagonal scanning magnetic recording/reproducing apparatus according to an embodiment of the present invention. 20: Central part of the outer periphery of the head drum, 21: Head drum, 22: Fixed guide. 23: Videotape.

Claims (1)

[Claims] The videotape is run at a predetermined speed by the capstan, and the operating point of the tension arm on the supply side is held at a fixed position, thereby applying a constant tension to the videotape and maintaining the tape tension at the head drum at a predetermined level. In an oblique scanning magnetic recording/reproducing device which is designed to have a value of
The current value of the capstan motor that drives the capstan is detected, and when the detected current value exceeds a predetermined value, the operating point of the supply side tension arm is moved to change the tension applied to the head. A diagonal scanning magnetic recording/reproducing device characterized in that the tape tension in the drum section is controlled to a desired value.