JPH06162745A - Method and device for calculating tape winding diameter - Google Patents

Abstract

PURPOSE:To accurately calculate the tape winding diameter regardless of the nonconstant-speed running state. CONSTITUTION:Rotation periods TS and TT of a supply reel and a take-up reel are detected in a detecting means 261 by frequency signals SFG and TFG. A tape speed V is detected in a detecting means 262 by a frequency signal CFG. Reel rotation periods TS and TT and, the tape speed V from detecting means 261 and 262 are supplied to a calculating means 263. This means 263 calculates tape diameters RS and RT of the supply reel and the take-up reel in the constant-speed running state by rotation periods TS and TT and the tape speed V and calculates a total area AA of both reels and an area AT of the take-up reel. A calculating means 264 corrects this area AT of the take-up reel in the nonconstant-speed running state in accordance with the extent of increase/reduction of the tape length due to rotation of the take-up reel and calculates tape winding diameters RS and RT by the area AT after correction. In the nonconstant-speed running state, rotation periods TS and TT and the tape speed V are not used to accurately calculate the tape winding diameters RS and RT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computing device and a computing method for computing the tape winding diameter of a supply reel or a take-up reel.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a tape traveling system of a known VTR and shows a loading state. In the figure, 1 is a supply reel, 2 is a take-up reel, 3 is a drum, 4 is a capstan, 5 is a pinch roller, and 6 is a tape.

By keeping the tape tension F of the P portion constant while the tape is running, it is possible to obtain a good head output and prevent the tape from being damaged by the tape guide or the like to improve the reliability of the tape path. it can.

Conventionally, in order to keep the tape tension F constant, the tape tension control of the forward (FWD) system is performed by a mechanical tension regulator, and the tape tension control of the reverse (RVS) system drives the reel stand. It has been proposed to use a current servo system that controls the current supplied to the reel motor according to the tape winding diameter.

As is well known, since the current I flowing through the reel motor and the torque generated by the motor are in a proportional relationship, if the tape winding diameter (radius) is R, the tape tension is F, and the torque generated by the reel stand is Tr, The relationship of Formula 1 will be satisfied.

[0006]

[Equation 1]

Considering mechanical loss and electrical loss, it can be expressed as shown in Equation 2. Where K1, K
2, A and B are constants, and A = K1 × F and B = K2. As a mechanical loss, the loss of the reel motor, the loss of the swing gear that transmits the driving force from the reel motor to the reel stand,
There is a loss of the reel stand, etc., and there is an error etc. generated in the current detection circuit as an electrical loss.

[0008]

[Equation 2]

As is clear from the equation (2), in order to keep the tape tension F constant, the motor current should be changed according to the tape winding diameter R. Tape winding diameter R
Is calculated from the reel rotation period and the tape speed as described in Japanese Patent Publication No. 58-17992. That is, the tape winding diameter of the supply reel 1 is RS, the tape winding diameter of the take-up reel 2 is RT, the rotation cycle of the supply reel 1 is TS, the rotation cycle of the take-up reel 2 is TT, the tape speed is V, and the tape 6 is. If the total area of the reel hub is AA, then the relational expression of Formula 3 can be obtained. Although detailed description is omitted, the tape winding diameters RS and RT can be calculated from these relational expressions if the reel rotation periods TS and TT and the tape speed V are known.

[0010]

[Equation 3]

FIG. 5 shows a tape tension controller for controlling the tape tension F to a constant value by controlling the current flowing through a reel motor that drives a reel base in a reverse system according to the tape winding diameter.

In the figure, 11 is a microcomputer (hereinafter referred to as "microcomputer"). This microcomputer 1
1 is a frequency signal SF from a frequency generator (not shown) attached to the supply reel 1 and the take-up reel 2.
G and TFG are supplied, and a frequency signal CFG from a frequency generator (not shown) attached to the capstan 4 is supplied. And in the microcomputer 11,
The rotation periods TS and TT of the supply reel 1 and the take-up reel 2 are obtained from the frequency signals SFG and TFG, and
The tape speed V is obtained from the frequency signal CFG, and the tape winding diameters RS and RT are calculated.

In the microcomputer 11, the tape winding diameter Rs of the supply reel 1 is used as the tape winding diameter R, and the tape winding diameter R
The current I (see the equation 2) corresponding to is calculated, and the calculated value is supplied to the PWM modulation circuit 12 in the microcomputer 11 as the control signal SCi. A PWM signal corresponding to the control signal SCi is output from the PWM modulation circuit 12, and the PWM signal is smoothed by the low pass filter 13 and then supplied to the constant current drive circuit 14. As a result, the supply reel 1
A current I corresponding to the tape winding diameter R is made to flow through the reel motor 15 that drives the tape motor F, and the tape tension F is controlled to be constant.

[0014]

By the way, as described above, the tape winding diameters RS and RT are obtained by using the rotation periods TS and TT and the tape speed V. For that purpose, the reel stand makes one rotation. It was a requirement that the inter-tape speed V be constant. That is, when the condition is not satisfied, for example, when the intermittent drive is performed during acceleration / deceleration or slow speed, the tape winding diameters RS and RT cannot be obtained and the previous value is held.

There is no problem in the case where this state ends immediately, but in the case where this state continues for a long time, the accurate tape winding diameters RS and RT cannot be obtained forever, and the accurate tape tension F is not obtained. There was a problem that it could not be controlled and caused tape damage.

In the case of detecting the tape position on the basis of the tape winding diameters Rs and RT, the so-called "gutsun" is caused by incorrect indication of the tape position or failure of detection near the tape top or tape end. stop"
There was a problem inviting.

Therefore, the present invention provides an arithmetic unit and an arithmetic method capable of accurately calculating the tape winding diameter even in a non-constant speed running state where the tape speed is not constant such as repeated acceleration and deceleration.

[0018]

A tape winding diameter calculating device according to a first aspect of the present invention comprises a first calculating device for calculating a tape winding diameter of a reel from a reel rotation period and a tape speed in a constant speed running state, Second calculating means for correcting the area corresponding to the tape winding diameter calculated by the first calculating means in accordance with the tape length increase / decrease in a non-constant speed running state, and calculating the tape winding diameter from the corrected area. It is equipped with and.

The tape winding diameter calculating method according to the second invention is
In the constant speed running state, the reel tape winding diameter is calculated from the reel rotation cycle and tape speed, and in the non-constant speed running state, the area corresponding to the tape winding diameter calculated in the constant speed running state is corrected according to the tape length increase / decrease amount. Then, the tape winding diameter is calculated from the corrected area.

[0020]

In the first and second aspects of the invention, in the non-constant speed running state where the tape speed is not constant due to repeated acceleration and deceleration, the area corresponding to the tape winding diameter calculated in the constant speed running state is used as the tape length increasing / decreasing amount. The tape winding diameter is calculated based on the corrected area, not the reel rotation cycle and the tape speed, and the tape winding diameter is calculated accurately even in a non-constant speed running state. It becomes possible to do.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In the figure, 21 is a supply reel, 22 is a take-up reel, 23 is a capstan, 24 is a pinch roller, and 25 is a tape.

Reference numeral 26 is a microcomputer for calculating the tape winding diameters RS and RT of the supply reel 21 and the take-up reel 22. This microcomputer 26 has reel 21,
The frequency signals SFG and TFG from the frequency generators 27 and 28 attached to 22 are amplified and waveform-shaped by the amplifiers 29 and 30, respectively, and supplied, and the frequency from the frequency generator 31 attached to the capstan 23 is supplied. The signal CFG is amplified and waveform-shaped by the amplifier 32 and supplied.

Further, the microcomputer 26 receives a signal SM indicating whether it is a constant speed running state or a non-constant speed running state where the tape speed is not constant such as repeated acceleration and deceleration, and the rotation direction of the take-up reel 22. Signal SD indicating whether it is the forward direction (FWD) or the reverse direction (RVS)
Is supplied.

The microcomputer 26 calculates the tape winding diameters RS and RT in the constant speed running state and the non-constant speed running state, respectively, based on the above-mentioned signals. 2 shows the microcomputer 2
6 shows 6 functional blocks.

The frequency signals SFG and TFG are supplied to the reel rotation cycle detecting means 261. The detection means 261 detects the rotation cycles TS and TT of the supply reel 21 and the take-up reel 22 from the frequency signals SFG and TFG, respectively. Further, the frequency signal CFG is supplied to the tape speed detecting means 262, and the detecting means 262 detects the tape speed V from the frequency signal CFG.

The rotation cycles TS and TT and the tape speed V detected by the detecting means 261 and 262 are supplied to the calculating means 263. In the constant speed running state, the calculating means 263 calculates the tape winding diameters Rs and RT of the supply reel 21 and the take-up reel 22 by using a conventionally well-known formula, for example, the formula 4 and at the same time as the supply reel 21. The total area AA obtained by adding the areas of both the tape 25 portions and the reel hub portion of the take-up reel 22, the tape 2 of the take-up reel 22
The area AT of the five parts and the reel hub part is calculated.

[0028]

[Equation 4]

Tape winding diameter R calculated by the calculating means 263
The T, the total area AA and the area AT are supplied to the calculating means 264. The computing means 264 computes the tape winding diameters RS and RT in the non-constant speed running state.

First, the tape length increase / decrease amount LT is obtained according to the frequency signal TFG and the rotation direction of the take-up reel 22.
That is, the initial value of the tape length increase / decrease amount LT is set to 0, and ΔL is added at each falling edge of the frequency signal TFG (FW
D rotation) or subtraction (RVS rotation). ΔL is the tape length increase / decrease amount per wave of the frequency signal TFG,
It is expressed as shown in Formula 5, and changes depending on the tape winding diameter RT. Note that n is the wave number of the frequency signal TFG generated by one rotation of the take-up reel 22.

[0031]

[Equation 5]

Next, the tape length increase / decrease amount LT is calculated as LT ≧ Lth (when FWD is rotated) or LT ≦ −Lth by the calculating means 264.
It is determined whether or not (during RVS rotation). The threshold Lth is
It is the tape length corresponding to the area of "1". And FW
At the time of D rotation and LT ≧ Lth, LT = LT−
After setting Lth, the area AT is corrected by setting AT = AT + 1,
The tape winding diameters RS and RT are calculated by the equation (6). On the other hand, RV
When S ≦ L and LT ≦ −Lth, LT = LT
After setting + Lth, the area AT is corrected by setting AT = AT-1, and the tape winding diameters RS and RT are calculated by the equation (6).

[0033]

[Equation 6]

Next, using the flow chart of FIG.
The calculation operation of the tape winding diameters RS and RT in the microcomputer 26 will be described.

First, it is determined from the signal SM whether or not the vehicle is traveling at a constant speed (step 101). When the vehicle is traveling at a constant speed, the supply reel 21 receives the frequency signals SFG and TFG.
The rotation speeds TS and TT of the take-up reel 22 are detected, and the tape speed V is detected from the frequency signal CFG (step 102), and the tapes of the supply reel 21 and the take-up reel 22 are calculated by the above formula (4). Roll diameter RS
And RT, the total area AA obtained by adding the areas of the tape 25 portion and the reel hub portion of both the supply reel 21 and the take-up reel 22, and the area AT of the tape 25 portion and the reel hub portion of the take-up reel 22 are calculated. The tape length increase / decrease amount LT is set to 0 (step 103) and the process returns to step 101.

In step 101, when the vehicle is not in the constant speed traveling state but in the non-constant speed traveling state, it is judged whether or not it is the falling edge of the frequency signal TFG (step 104). When the frequency signal TFG does not fall, step 101
Return to. When the frequency signal TFG is falling,
The rotation direction of the take-up reel 22 is determined from the signal SD (step 105).

In step 105, when the rotation direction is FWD, the tape length increase / decrease amount LT is set to 1 of the frequency signal TFG.
Add the tape length increase / decrease amount ΔL per wave (step 10
6), it is determined whether LT ≧ Lth (step 1
07). If LT ≧ Lth is not satisfied, the process returns to step 101. When LT ≧ Lth, LT = LT-Lth is set, then AT = AT + 1 is set to correct the area AT, and the tape winding diameters RS and RT are calculated by the above-described equation 6 (step 10).
8) Return to step 101.

When the rotation direction is RVS at step 105, the tape length increase / decrease amount ΔL per wave of the frequency signal TFG is subtracted from the tape length increase / decrease amount LT (step 10).
9), it is determined whether LT≤-Lth (step 110). If LT ≦ −Lth is not satisfied, the process returns to step 101. When LT≤-Lth, LT = LT + Lth is set, then AT = AT-1 is set to correct the area AT, and the tape winding diameters RS and RT are calculated by the equation (6) (step 1).
11) and returns to step 101.

As described above, in this embodiment, the tape winding diameters RS and RT are calculated from the reel rotation periods TS and TT and the tape speed V in the constant speed running state. On the other hand, in a non-constant speed running state in which the tape speed is not constant, such as repeated acceleration and deceleration, the area AT (= πRT ² ) of the take-up reel 22 calculated in the constant speed running state becomes the tape length increase / decrease amount LT. The tape winding diameter RS, RT is corrected according to the corrected area AT.
Is calculated. That is, in the non-constant speed running state, the reel winding periods TS, TT and the tape speed V are not used to calculate the tape winding diameters RS, RT, and the tape winding diameters RS, RT are not used in the non-constant speed running state. Can be calculated accurately.

In the above embodiment, the area AT is corrected according to the tape length increase / decrease amount LT of the take-up reel 22,
Although the tape winding diameters Rs and RT are calculated from the corrected area AT and the processing is performed on the take-up reel 22 side, the area is similarly changed according to the tape increase / decrease amount of the supply reel 21. Correct the tape winding diameter R from the corrected area
It is also possible to calculate s and RT.

Further, in the above embodiment, only the frequency signal TFG is used in the non-constant speed running state, and the frequency signal CFG is unnecessary, so that the tape winding diameters RS and RT are not used even when the capstan 23 is not used. Can be accurately calculated.

[0042]

According to the first and second aspects of the present invention, in a non-constant speed running state where the tape speed is not constant such as repeated acceleration and deceleration, the area corresponding to the tape winding diameter calculated in the constant speed running state is set. The tape winding diameter is calculated from the corrected area according to the tape length increase / decrease amount, not the reel rotation cycle and the tape speed.
The tape winding diameter can be accurately calculated even in the non-constant speed running state.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing functional blocks of a microcomputer in the example of FIG.

FIG. 3 is a flowchart showing a tape winding diameter calculation operation of the microcomputer of the example of FIG.

FIG. 4 is a diagram showing an example of a tape running system of a VTR.

FIG. 5 is a configuration diagram showing a tape tension control device.

[Explanation of symbols]

 21 Supply Reel 22 Winding Reel 23 Capstan 24 Pinch Roller 25 Tape 26 Microcomputer 27, 28, 31 Frequency Generator 29, 30, 32 Amplifier 261 Reel Rotation Cycle Detection Means 262 Tape Speed Detection Means 263, 264 Computing Means

Claims (2)

[Claims] 1. A first arithmetic unit for calculating a reel tape winding diameter from a reel rotation period and a tape speed in a constant speed running state, and the first calculation according to a tape length increase / decrease amount in a non-constant speed running state. A tape winding diameter calculating device comprising: a second calculating means for correcting an area corresponding to the tape winding diameter calculated by the means, and calculating the tape winding diameter from the corrected area. 2. The tape winding diameter calculated in the constant speed running state from the reel rotation cycle and the tape speed, and in the non-constant speed running state, calculated in the constant speed running state according to the tape length increase / decrease amount. Correct the area corresponding to
A method for calculating a tape winding diameter, which comprises calculating a tape winding diameter from a corrected area.