JPH06309739A - Tape tension control device - Google Patents

Abstract

PURPOSE:To make the device compact and to realize highly accurate control of tape tension by absorbing load variation caused by passing of a tape through a running system and load variation caused by variation of contact conditions between a tape and a cylinder. CONSTITUTION:In order to adjust rotation phases of a cylinder and a capstan (phase control), quantity of phase deviation between a reference signal generated by a cylinder PG and an output signal of FG1 are calculated and added to quantity of a speed error to make an error signal of the capstan. Also, at the same time, a CTL signal is recorded at a prescribed position on a tape. Quantity of controlling the capstan obtained by these procedure is sent to a reel control system, compared with an output signal of a reference quantity setting section 10, and the difference is outputted from a subtracter 11. Thus, variation part of tape tension is obtained, a prescribed bias value is added to this variation part via a bias adding means 13, the resultant signal is converted by a PWM means 14, and outputted as quantity of controlling reel driving.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a VTR (VIDEO TAPE RECO
The present invention relates to a tape tension control device for maintaining a constant tape tension during recording, reproduction and special reproduction (fast forward search, reverse search, etc.) of a recording / reproducing device using a cassette tape such as RDER) or DAT (DESITAL AUDIO TAPE).

[0002]

2. Description of the Related Art In a recording / reproducing apparatus such as a VTR or DAT,
If the tension of the tape is too weak, the contact between the tape and the magnetic head for recording / reproducing becomes unstable and signal loss may occur, while if it is too strong, the friction of the head increases and the tape may be damaged, However, there is a problem in that the load torque of the rotating cylinder in which the is mounted increases and uneven rotation occurs.

Further, since the tape is in intricate contact with a cylinder, a post, etc., friction resistance of various sizes is generated in each part, which causes the tape to partially expand and contract, and in particular, at the inlet and outlet of the cylinder. Between the tapes, the difference in the tape expansion rate is likely to occur, and the phase of the horizontal sync signal due to the difference in the switching of the video tracks is deviated, causing the skew distortion that the upper part of the reproduced screen is curved to the left or right. was there.

One method for solving the above problems is to add a control mechanism for keeping the tension of the tape constant. As a general control mechanism, there are many simple mechanical servos in which the tension arm is linked to the reel brake, while in high-end models such as commercial VTRs, the reel uses the direct drive system, so the tension is separate. A detection mechanism (a detection mechanism using a Hall element and a spring, etc.) is provided, and a method of directly detecting the tension fluctuation and feeding it back to the reel on the tape feeding side is adopted (for example, Japanese Patent Laid-Open No. 3-97149 ( G11B 1
5/61) Reference).

[0005]

As described above, in the conventional tension arm system such as VTR for home use, the control cannot follow abrupt tape tension fluctuation, and the tape running system has a tape running system. Since it is impossible to suppress the fluctuation of the tape tension due to the fluctuation of the load, there is a problem that the tape tension cannot be kept constant with high accuracy.

In particular, in a high-end model such as a VTR for business use, the direct drive system is adopted for the reel as described above to control the reel with high accuracy. In this method, however, some mechanism for tension detection and its detection signal processing are used. However, there is a problem that the number of parts is increased and the mechanism and the circuit section are complicated.

The present invention has been made in view of the above problems of the prior art, and maintains the tape tension constant with high accuracy without using an additional mechanism for tension detection or a circuit for processing a detection signal. It is an object of the present invention to provide a control device capable of performing the above.

[0008]

According to the present invention, a capstan control amount calculating means for calculating a control amount of a capstan from a speed error signal and a phase error signal of a capstan system, and the capstan control amount as a reference amount. It comprises a fluctuation amount calculating means for comparing and calculating a fluctuation amount of the capstan control amount, and a bias adding means for adding a predetermined bias value to the fluctuation amount and outputting a reel control amount.

[0009]

Normally, capstan control in a VTR or the like absorbs load fluctuations caused when the tape passes through the running system and load fluctuations caused by changes in the contact state between the tape and the cylinder, and the tape is fed at a constant speed and a reference signal is used. In contrast, the reel torque is controlled so that the vehicle travels while maintaining a fixed positional relationship. At this time, the above-mentioned load fluctuation applied to the capstan is directly related to the change of the tape tension, and the fluctuation amount is reflected in the control signal of the capstan.

According to the structure of the present invention, the fluctuation of the control signal of the capstan that directly expresses the fluctuation of the tension is fed back to the reel on the tape feeding side, so that the absolute value of the tape tension is kept constant, and the fluctuation thereof is further maintained. Is to suppress.

Therefore, the capstan control signal, which directly represents the fluctuation of the tape tension, is fed back to the reel on the tape feeding side to perform the tension control, so that the tension of the dedicated mechanism is higher than that of the conventional mechanical mechanism. The tension can be kept constant without a detection mechanism or signal processing circuit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the tape tension control device of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit block diagram showing the configuration of the apparatus, in which 1 is a frequency generator (FG) necessary for controlling the capstan, and 2 is a control (Con).
signal generator, 3 is a frequency divider that receives the output of the FG, 4 is speed error calculation means for calculating the speed error of the capstan from the output of the frequency divider, and 5 is the CT
Phase error calculating means for calculating the phase error of the drive of the capstan from the output of the L signal generator 2, 6 is an adder for adding the outputs of the speed and phase error calculating sections 4, 5, and 7 is the adder 6 The capstan control amount calculation unit for calculating the control amount of the capstan based on the output of the
Width Modulation) means, and the output of the PWM means 8 becomes a capstan control signal 9.

The FG1 and CTL signal generator 2
To the output of the capstan control signal 9 form a capstan control system.

Next, 10 is a reference amount setting unit set to a control amount when the capstan is unloaded (when the capstan is rotating by itself), and 11 is an output of the capstan control amount calculating unit 7. And a reference value setting section output from the subtracter, 12 is a tension fluctuation calculating section for calculating a load fluctuation of the capstan due to the tape running by the output of the subtractor, and 13 is the tension. Bias adding means for adding a predetermined bias value to the output of the fluctuation calculating section 12, 14 is a second PWM means for converting the output of the bias adding means 13, and the output of the PWM means 14 is a supply reel control signal. It will be 15.

The input of the reference amount setting section 10 to the output of the supply reel control signal 15 constitute a reel control system.

Further, in the above structure, the division period 3 to the first P
The WM means 8 and the reference amount setting section 10 to the second PWM means 14 are composed of only one microprocessor.

Now, the role of the capstan FG signal will be described. The output signal of the FG1 and the CTL signal are T-important signals even when the speed control and the phase control are performed in the capstan rotation control. At the time of recording, in order to keep the rotation speed of the capstan at a certain reference rotation speed (speed control), the own rotation speed is detected as the output signal of FG1 in that cycle, and the difference from the reference cycle is taken to deviate from the reference. Calculate the amount (speed error amount).

Further, in order to match the rotational phase of the cylinder and the capstan (phase control), a cylinder PG (Phase Ge
The amount of phase shift (phase error amount) between the reference signal generated from the nerator) and the output signal of FG1 (divided to have the same period as the reference signal) is calculated and added to the preceding speed error amount to cap. Making a stun error signal. At the same time, the CTL signal is recorded at a predetermined position on the tape.

On the other hand, during reproduction, the speed control is the same as during recording, but the phase control is slightly different. That is, the signal for knowing the information of the head and the tape position is the CTL signal so that the head can trace the recorded track well during reproduction, and the phase relationship between the CTL signal and the reference signal generated from the cylinder PG is kept constant. Phase control is performed as follows. In this way, the capstan control signal is generated,
The speed unevenness information (tension fluctuation) due to the load fluctuation of the tape running system can be understood by looking at the control signal of the capstan.

Further, the PWM means 8 and 14 are provided for smoothing a rectangular wave PWM signal through an external filter (not shown) for the control signals 9 and 15 and extracting it as a DC signal. Is.

In the capstan control system in the tape tension control device having such a configuration, the speed error signal and the phase error signal are respectively the speed error calculation means 4 and the phase error from the output signal of the FG1 and the output signal of the CTL signal generator 2. The capstan control amount is calculated by the calculating means 5, and the adder 6 and the capstan control amount calculating unit 7 determine the capstan control amount. The capstan control amount is a control amount including a load variation in the VTR mechanical system, that is, a tape tension variation.

The capstan control amount thus obtained is sent to the reel control system, compared with the output signal of the reference amount setting section 10, and the difference is output from the subtracter 11. As mentioned above, the reference amount is set to the control amount when the capstan is unloaded, so if the difference between the capstan control amount and the reference amount is taken when the tape is running, the capstan control amount due to the tape running It means that the variation, that is, the variation of the tape tension can be extracted.

In this way, the fluctuation of the tape tension is obtained, and a predetermined bias value is added to the fluctuation by the bias adding means 13 and converted by the PWM means 14 to obtain a reel drive control amount. Output. Explaining the bias value, the error detection amount is calculated as a difference between a predetermined reference value and a detection value (here, the cycle of the output signal of FG1). Therefore, if the error detection amount matches the reference value, the error is detected. The amount becomes 0. Even at this time, the control signal 9,
The output value of 14 is not 0 but is set to a certain fixed value, and that value is a value determined by the design of the device, and this is called a bias value. Of course, if there is an error amount, the bias value is added to it and output.

The tape tension value can be set arbitrarily by changing the value of the bias value added by the bias adding means 13.

The above embodiment describes an apparatus for controlling tape tension during reproduction. Since the reel on the tape feeding side is the supply reel, the calculated control signal is output to the supply reel. It goes without saying that the present invention can be applied to recording, fast-forward search, and reverse search.

[0027]

As described above, according to the present invention, since the reel drive control can be performed only by extracting the variation of the capstan control signal, the tape tension detector dedicated to the control and the detection signal processing circuit can be omitted. Therefore, the system can be made compact, and the tape tension control with high accuracy can be realized.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a tape tension control device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 FG 2 CTL signal generator 4 Velocity error calculation means 5 Phase error calculation means 7 Capstan control amount calculation means 10 Reference amount setting section 12 Fluctuation amount calculation means

Claims (1)

[Claims] 1. A capstan control amount calculating means for calculating a control amount of a capstan from a speed error signal and a phase error signal of a capstan system, and a fluctuation of the capstan control amount by comparing the capstan control amount with a reference amount. A tape tension control device comprising: a fluctuation amount calculating means for calculating a minute amount; and a bias adding means for adding a predetermined bias value to the fluctuation amount and outputting a reel control amount.