JPH06150455A - Tape tension controller - Google Patents

Abstract

PURPOSE:To control a tape tension in a constant state by absorbing the variance for each set, and to unnecessitate a large capacity ROM. CONSTITUTION:When the set is used, the current I corresponding to a tape winding diameter R for making the tape tension F constant in a microcomputer 11 is calculated by an approximate expression, and the calculated value is supplied to a modulation circuit 12 as a control signal SCi, and a PWM signal corresponding to the control signal SCi is obtained from this modulation circuit 12, then a motor 15 is driven by smoothing the PWM signal by an LPF 13 and supplying it to a constant current drive circuit 14. At the time of adjustment in a production line, constants A-C in the approximate expression optimum for each set are stored in the ROM 21, then the constants A-C are read out from the ROM 21 and used, when the current I is calculated. The tape tension can be controlled in the constant state since the variance for each set is perfectly absorbed. The large capacity ROM is unnecessitated as the current I is obtained by the calculation of the approximate expression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is applicable to, for example, VTRs and DAs.
The present invention relates to a tape tension control device suitable for application to a tape transport system using a helical scan such as T.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventionally known VTR tape running system 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]

Actually, there is a fixed loss due to some mechanical loss and some electrical loss, and there is a variable loss proportional to the rotation speed of the motor, which can be expressed by the approximate expression of Equation 2. . Where V is the tape speed. Also,
K1 to K3 and A to C are constants, and A = K1 × F and B =
K2 and C = K3 / 2π. The mechanical loss is a loss of the reel motor, a loss of the swing gear that transmits the driving force from the reel motor to the reel base, a loss of the reel base, and the like, and the electrical loss is an error generated in the current detection circuit. Further, the loss of the fluctuation component is mainly due to the eddy current loss of the reel motor 15.

[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 period and the tape speed are known.

[0010]

[Equation 3]

FIG. 4 shows a tape tension control device 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 TFG and SFG, 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, the microcomputer 1
As described above in 1, the ROM conversion table is generally used to obtain the current I corresponding to the tape winding diameter R. That is, the tape winding diameter R and the tape speed V are RO
By using the input address of M, the current I is obtained from this ROM by the approximate expression of Equation 2.

In this case, since average values are used as the constants A to C in the approximate expression of the equation 2, there is a problem that the tape tension controlled for each set varies. Further, since the ROM uses the tape winding diameter R and the tape speed V as input addresses, there is a problem that a large capacity ROM is required.

An object of the present invention is to absorb variations in each set and control the tape tension constant, and
It is to provide a tape tension control device that does not require a large capacity ROM.

[0017]

According to a first aspect of the present invention, in a tape tension controller for controlling a tape tension to a constant value by causing a current corresponding to a tape winding diameter to flow through a reel motor for driving a reel stand, the current is supplied to a tape speed controller. And a non-volatile memory that stores a constant of the approximate expression, and an arithmetic means that performs an approximate expression using the tape winding diameter as a parameter, and the arithmetic means uses the constant of the approximate expression stored in the non-volatile memory. It calculates the current.

A second aspect of the invention is a tape tension control device for controlling a tape tension to a constant value by supplying a current corresponding to a tape winding diameter to a reel motor for driving a reel base, and setting the current as a parameter of a tape speed and a tape winding diameter. And an arithmetic means for performing an arithmetic operation with an approximate expression, a non-volatile memory for storing a constant of the approximate expression, and a temperature detecting means for detecting an environmental temperature. The arithmetic means has a constant for the approximate expression stored in the non-volatile memory. Is calculated according to the environmental temperature detected by the temperature detecting means and then used to calculate the current.

[0019]

According to the first aspect of the invention, the current corresponding to the tape winding diameter is calculated using the constant of the approximate expression stored in the non-volatile memory, which is optimal for each set at the time of adjustment on the manufacturing line. By calculating the constant of the approximate expression and storing it in the non-volatile memory, it is possible to completely absorb the variation for each set and to control the tape tension constant. Further, since the ROM conversion table is not used, a large capacity ROM is unnecessary.

In the second invention, in addition to the operation of the first invention, the arithmetic means corrects the constant of the approximate expression in accordance with the environmental temperature and then uses it. Even when the environmental temperature at the time of adjustment in which the constant is stored is different, an appropriate current can be calculated, and the tape tension can be controlled to be constant regardless of the environmental temperature.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, 21 is a constant A of the approximate expression of equation 2.
Is an EEPROM as a non-volatile memory that stores C to C. The EEPROM 21 stores optimum constants A to C for each set at the time of adjustment on the manufacturing line.

Here, the constants A to C to be stored in the ROM 21 are calculated by the computer as follows when adjusting the manufacturing line. [Step 1] First, the tape cassette near the tape top is loaded into the set, and the tape 6 is set in the low speed mode (for example, ×
1), the control signal SCi supplied to the PWM modulation circuit 12 is changed by the computer 31 so that the tape tension F becomes the optimum value, and the current I flowing through the reel motor 15 is adjusted. In this case, the conventionally known tension sensor 32 detects the tape tension F,
The detection information is supplied to the computer 31. Here, when the current when the tape tension F reaches the optimum value is I1, and the tape winding diameter at that time is R1 and the tape speed is V1, the relational expression of Formula 4 is established.

[0024]

[Equation 4]

[Step 2] Next, the tape cassette near the tape end is loaded into the set, the tape 6 is run in the low speed mode (for example, x1), and the computer 31 adjusts the tape tension F to an optimum value. The control signal SCi supplied to the PWM modulation circuit 12 is changed to adjust the current I flowing through the reel motor 15. When the current when the tape tension F reaches the optimum value is I2, and the tape winding diameter is R2 and the tape speed is V2 at that time, the relational expression of Formula 5 is established.

[0026]

[Equation 5]

Since the tape speeds V1 and V2 at the tape top and tape end are considered to be almost the same,
In the computer 31, the constants A and B are calculated from the equations (4) and (5) with V1 = V2≈0. [Step 3] Next, a tape cassette near the tape end (the reel motor 15 rotates rapidly) is loaded into the set, the tape 6 is run in the high speed mode (for example, × 75), and the tape tension F becomes the optimum value. Control signal S supplied to the PWM modulation circuit 12 by the computer 31 so that
The current flowing through the reel motor 15 is adjusted by changing Ci. In this case, the computer 31 uses the constants A and B calculated in step 2, calculates the current I by the equation 2 while changing the constant C, and calculates the calculated value as the PWM modulation circuit 1
2 as a control signal SCi. Then, the constant C when the tape tension F reaches the optimum value is set as a value to be obtained.

The constants A to C obtained in the above-described steps 1 to 3 are written in the ROM 21 from the computer 31 via the microcomputer 11, and thus the RO
The constants A to C are stored in M21. Constant A in ROM 21
After C to C are written, the computer 31 is separated from the microcomputer 11.

When using the set, the microcomputer 11 has a ROM
21 from the constant A written at the time of adjustment as described above
C is read, the current I is calculated by the equation 2, and the calculated value is supplied to the PWM modulation circuit 12 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, a current I corresponding to the tape winding diameter R is caused to flow in the reel motor 15 that drives the supply reel 1, and the tape tension F is controlled to be constant.

In the present embodiment, the ROM 21 stores constants A to C of the optimum approximate expression for each set, and when the set is used, the constants A to C are used to calculate the current I corresponding to the tape winding diameter R. Therefore, it is possible to completely absorb the variation for each set and to control the tape tension F to be constant. In this example, the current I corresponding to the tape winding diameter R
R is calculated in the microcomputer 11 using the equation (2),
Large capacity ROM since OM conversion table is not used
Is unnecessary.

By the way, in the example of FIG. 1, the constants A to C are obtained and stored in the ROM 21 at the time of adjustment on the manufacturing line.
When using the set, the constants A to C are read from the ROM 21 and used as they are.

However, the constants A to S stored in the ROM 21
C is the optimum temperature for the environment temperature at the time of adjustment, and is not necessarily the optimum temperature for the environment during use of the set.

FIG. 2 shows another embodiment of the present invention in which the tape tension F can be controlled to be constant regardless of the environmental temperature when the set is used. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, reference numeral 41 is a temperature detection circuit composed of a thermistor or the like for detecting the environmental temperature, and temperature information S (t) indicating the environmental temperature t from the temperature detection circuit 41 is supplied to the microcomputer 11. .

In this example, constants A to C are written in the ROM 21 at the time of adjustment on the manufacturing line, and temperature information S (t0) indicating the environmental temperature t0 at the time of adjustment is also written.

Here, the constants A, B, and C are regarded as functions of the ambient temperature t, and A (t), B (t), and C respectively.
(t). When each tendency was examined by taking data, it was found that it could be approximated by the equation (6). That is,
The constants A and B have almost no temperature dependence, and the constant C can be approximated by a quadratic function of temperature. In addition, in Expression 6, A (t0), B
(t0) and C (t0) are constants written in the ROM 21 during adjustment, and K is a fixed constant. The fixed constant K can be obtained by taking data.

[0037]

[Equation 6]

In this example, when the set is used, the microcomputer 1
1 is a constant A (t0), B (t0), C (t0) from the ROM 21.
Is read out, temperature information S (t0) indicating the environmental temperature t0 at the time of adjustment is read out, and the constants A (t), B (t), and C (t) that have been temperature-corrected by Equation 6 are calculated. Then, as the constants A, B, and C of the equation 2, constants A (t), B (t), and C, respectively.
Calculate the current I according to the tape winding diameter R using (t),
The calculated value is supplied to the PWM modulation circuit 12 as the control signal SCi.

In this example, the temperature-corrected constant A
Since the current I corresponding to the tape winding diameter R is calculated using (t), B (t), and C (t), even if the environmental temperature t is different from the environmental temperature t0 at the time of adjustment, the appropriate current I Can be calculated, and the tape tension F can be controlled to be constant regardless of the environmental temperature t.

The temperature information S (t0) indicating the environmental temperature t0 at the time of adjustment from the temperature detection circuit 41 is stored in the ROM 21 as a constant A.
(t0), B (t0), and C (t0) are written, and the constants A (t), B (t), and C (t) are calculated by using the environmental temperature t0 at the time of adjustment as a reference when using the set. Therefore, it does not depend on the environment at the time of adjustment, the variation of the temperature detection circuit 41 can be absorbed, and the tape tension F can be controlled to be constant.

It should be noted that the relational expression of the equation 6 is an example in a certain system, and it may be considered that another system cannot be approximated to a function neatly. In that case, the temperature-corrected constants A (t), B (t), and C (t) may be obtained using a table.

[0042]

According to the first aspect of the present invention, the current according to the tape winding diameter is calculated using the constant of the approximate expression stored in the non-volatile memory. By obtaining the optimum approximate equation constant and storing it in the non-volatile memory, it is possible to completely absorb the variation for each set and to control the tape tension constant.
Moreover, there is an effect that a large-capacity ROM is unnecessary because a ROM conversion table is not used.

According to the second invention, the same effect as that of the first invention can be obtained, and in addition, since the arithmetic means corrects the constant of the approximate expression according to the environmental temperature and then uses it, the environmental temperature is non-volatile. The proper current can be calculated even when the ambient temperature at the time of adjustment in which the constant of the approximate expression is stored in the performance memory is different, and the tape tension can be constantly controlled regardless of the ambient temperature.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a tape tension control device according to the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the tape tension control device according to the present invention.

FIG. 3 is a diagram showing an example of a tape traveling system of a VTR.

FIG. 4 is a configuration diagram showing a conventional tape tension control device.

[Explanation of symbols]

 1 Supply reel 2 Take-up reel 3 Drum 4 Capstan 5 Pinch roller 6 Tape 11 Microcomputer 12 PWM modulation circuit 13 Low pass filter 14 Constant current drive circuit 15 Reel motor 21 EEPROM 31 Computer 32 Tension sensor 41 Temperature detection circuit

Claims (4)

[Claims] 1. A tape tension control device for controlling a tape tension to a constant value by causing a current corresponding to a tape winding diameter to flow through a reel motor for driving a reel stand, wherein the current is approximated by using a tape speed and a tape winding diameter as parameters. An arithmetic means for performing an arithmetic operation and a non-volatile memory for storing the constant of the approximate expression are provided, and the arithmetic means calculates the current by using the constant of the approximate expression stored in the non-volatile memory. A tape tension control device characterized in that 2. When the current is I, the tape winding diameter is R, and the tape speed is V, the approximate expression is I = A × R + B + C × V / R (A, B, and C are constants) The tape tension control device according to claim 1, wherein the tape tension control device is provided. 3. The constants A, B, and C are determined by adjusting the current flowing through the reel motor so that the tape speed V becomes low and high, and the tape tension becomes constant at each of them. Claim 2 characterized by the above-mentioned.
The tape tension control device described. 4. A tape tension control device for controlling a tape tension to a constant value by causing a current corresponding to a tape winding diameter to flow through a reel motor for driving a reel stand, wherein the current is approximated by using a tape speed and a tape winding diameter as parameters. An arithmetic means for performing an arithmetic operation, a non-volatile memory for storing constants of the approximate expression, and a temperature detecting means for detecting an environmental temperature are provided, and the arithmetic means stores the approximate expression of the approximate expression stored in the non-volatile memory. A tape tension control device, characterized in that a constant is corrected according to an environmental temperature detected by the temperature detecting means and then used to calculate the current.