JP3146873B2 - Control device for electromechanical transducer with non-linear displacement characteristics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric machine having a non-linear displacement characteristic for driving a reproducing head in a magnetic recording / reproducing apparatus (hereinafter referred to as VTR) having a reproducing head drivable in the width direction of a recording track. The present invention relates to a control device for a conversion element.

[0002]

2. Description of the Related Art In recent years, in a VTR, a reproducing head is mounted on a parallel link type head driving element using two electromechanical transducers such as a bimorph type piezoelectric element, and can be driven in the width direction of a recording track. A VTR that enables noiseless special reproduction has been put to practical use.

In such a VTR, the non-linear displacement characteristic of an electromechanical transducer for driving a reproducing head in the width direction of a recording track has been a serious problem in performing noiseless special reproduction.

[0004] By the way, noiseless special reproduction in a VTR is reproduction when the tape speed is different from that in normal reproduction, and the reproduction is performed without noise.

FIG. 9 is a diagram showing a relationship between a scanning locus of a reproducing head (not shown) and a recording track in a two-head helical scan type VTR. Reference numeral 901 denotes a magnetic tape; 902, a transport direction of the magnetic tape; and 903, a scanning direction of the reproducing head. A1, A2,..., B1,
B2,... Indicate recording tracks when two recording heads (not shown) are an A head and a B head, respectively. The scanning trajectory by which the reproducing head scans the recording track during normal reproduction is 904. However, when the tape speed is different from that at the time of normal reproduction, for example, when the speed is 3 times speed, the scanning locus of the reproducing head is 905 and 906. The reproducing head crosses the recording track, and reproduces a reproduced image with noise. Therefore, in order to obtain a reproduced image without noise, when the reproducing head scans the recording track, the reproducing head is moved in the width direction of the recording track by two track pitches at the end of the recording track. It is clear that the reproducing head should be driven. That is, the reproducing head is driven in a sawtooth waveform, and the target value of the control device of the electromechanical transducer for driving the reproducing head is a sawtooth waveform.

FIG. 10 shows a relationship between a target value of displacement of the electromechanical transducer and displacement information of the driven electromechanical transducer. The vertical axis is voltage and the horizontal axis is time. Displacement information of the electromechanical transducer is detected by a displacement detecting means,
It is converted to voltage and detected. An alternate long and short dash line indicates a target value, and a solid line indicates displacement information. Since the electromechanical transducer has non-linear displacement characteristics, the displacement is different from the target value, and it is difficult to make the reproducing head on-track with respect to the recording track.

In order to solve this problem, in the prior art, as disclosed in Japanese Patent Application Laid-Open No. H2-134884, the nonlinear displacement characteristic of the electromechanical transducer is divided into sections appropriately divided by the displacement of the electromechanical transducer. Nonlinear correction was performed by linear approximation.

A conventional control device for an electromechanical transducer having nonlinear displacement characteristics will be described with reference to FIGS. 11 and 12. FIG.

FIG. 11 is a block diagram showing a configuration of a conventional controller for an electromechanical transducer having nonlinear displacement characteristics.

Reference numeral 1101 denotes an electromechanical transducer having an output displacement characteristic with respect to an input voltage having a non-linear displacement characteristic.
Is a target value generating means for generating a target value of the displacement of the electromechanical transducer 1101; 1103 is an electromechanical transducer 1101;
Non-linear correction means 1104 for linearly correcting the output displacement characteristic with respect to the target value is driven by a driving means for driving the electromechanical transducer 1101 according to the operation amount obtained from the non-linear correction means 1103.

FIG. 12 is a diagram showing the relationship between the applied voltage and the displacement of the electromechanical transducer. The vertical axis is displacement, and the horizontal axis is applied voltage. A solid line indicates the output displacement characteristic of the electromechanical transducer 1101, a broken line indicates an approximate straight line of the output displacement characteristic, and a dashed line indicates a desired output displacement characteristic. The above-described approximate straight line is used as the output displacement characteristic of the electromechanical transducer 1101, and the nonlinear correction means 1103 corrects the nonlinear characteristic of the output displacement characteristic for each section of the output displacement so that a desired output displacement characteristic is obtained. Specifically, for example, if D1 is required as the displacement, if the desired linear output displacement characteristic is satisfied, V1 may be applied to the electromechanical transducer 1101 as the applied voltage. Electromechanical transducer 110
1 has a non-linear output displacement characteristic, and the applied voltage V1
In this case, the displacement becomes D2. Therefore, in order to obtain D1 which is a necessary displacement, nonlinear correction has been performed so that the applied voltage applied to the electromechanical transducer 1101 is not V1 but V2.

[0012]

However, in the above-described conventional configuration, an approximate straight line for performing non-linear correction must be obtained in advance for each section, and one obtained approximate straight line is required. Therefore, there is a problem that it is not possible to cope with the variation of the nonlinear displacement characteristics of the electromechanical transducer 1101 and the electromechanical transducer 1101 having different nonlinear displacement properties.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a control device for an electromechanical transducer having a non-linear displacement characteristic capable of performing more accurate control.

[0014]

According to the present invention, there is provided a controller for an electromechanical transducer having a non-linear displacement characteristic, wherein the output displacement characteristic with respect to an input voltage has a non-linear displacement characteristic. , the target value generation means for generating a target value of the displacement of the electromechanical transducer, the output displacement characteristic with respect to the target value of the electromechanical conversion element is corrected to a linear
Nonlinear correction factor which becomes the slope of the operation amount of the electromechanical transducer
Number and set the electromechanical transformation based on the set nonlinear correction coefficient.
Non-linear correction coefficient generating means for calculating the operation amount of the switching element ,
A non-linear correction coefficient storing means for storing a nonlinear compensation coefficient generated by the non-linear correction coefficient generation unit, electrically based on non-linear correction coefficient stored in the non-linear correction coefficient storing means
Non-linear correction means for calculating the operation amount of the mechanical conversion element, switching means for switching between the operation amount obtained from the non-linear correction coefficient generation means and the operation amount obtained from the non-linear correction means, and the operation amount switched by the switching means A driving means for driving the electromechanical transducer, and a displacement detecting means for detecting a displacement of the electromechanical transducer, wherein the nonlinear correction coefficient generating means obtains the target value and the displacement detecting means having a periodic sawtooth waveform. The displacement information is sampled a plurality of times within one cycle, and a nonlinear correction coefficient is set so that the difference between the target value and the displacement information is within a predetermined range. The operation amount obtained by the non-linear correction coefficient generating means is selected until is set, and the operation amount obtained by the non-linear correction means is selected after the setting is performed. A control device for an electromechanical transducer having a displacement characteristics.

[0015]

According to the present invention, the nonlinear correction coefficient generating means samples the periodic sawtooth wave target value and the displacement information obtained from the displacement detecting means a plurality of times in one cycle. Setting a nonlinear correction coefficient that is a gradient of the operation amount of the electromechanical transducer so that the difference between the target value and the displacement information is within a predetermined range, and based on the set nonlinear correction coefficient,
The operation amount of the mechanical conversion element is calculated, and in the switching means,
Until the nonlinear correction coefficient is set, the operation amount obtained by the non-linear correction coefficient generation means is selected, and after the setting, the operation amount obtained by the non-linear correction means is selected. Is automatically corrected so that the difference between the target value and the displacement information falls within a predetermined range, and simple and highly accurate control is performed.

[0016]

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

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In FIG. 1, reference numeral 101 denotes an electromechanical transducer having an output displacement characteristic with respect to an input voltage having a non-linear displacement characteristic; 102, a target value generating means for generating a target value of displacement of the electromechanical transducer 101; Non-linear correction coefficient generating means 104 for linearly correcting the output displacement characteristic with respect to the target value of the non-linear correction coefficient; 104, a non-linear correction coefficient storing means for storing the non-linear correction coefficient generated by the non-linear correction coefficient generating means 103; before based on non-linear correction coefficient stored in the
Non-linear correction means 106 for calculating the operation amount of the electromechanical transducer , switching means 106 for switching between the operation amount obtained from the non-linear correction coefficient generation means 103 and the operation amount obtained from the non-linear correction means 105, and 107 for the switching means 10
6, a driving means for driving the electromechanical transducer 101 in accordance with the operation amount switched by 6, a displacement detecting means 108 for detecting the displacement of the electromechanical transducer 101, and a non-linear correction coefficient generating means 103, The waveform-like target value and the displacement information obtained from the displacement detection means 108 are sampled a plurality of times in one cycle, and a nonlinear correction coefficient is set so that the difference between the target value and the displacement information is within a predetermined range.
The switching unit 106 selects an operation amount obtained from the nonlinear correction coefficient generation unit 103 until the nonlinear correction coefficient is set, and then selects an operation amount obtained from the nonlinear correction unit 105 after the setting. I have.

The switching signal W is a signal obtained from a VTR system control (hereinafter, referred to as a system controller, not shown).

The operation of the control device for an electromechanical transducer having a nonlinear displacement characteristic according to the present embodiment having the above-described configuration will be described below with reference to FIGS.

FIG. 2 is a diagram showing the relationship between the target value R of displacement of the electromechanical transducer 101 and the displacement information F and the manipulated variable P in the non-linear correction means 105. The vertical axis represents voltage, and the horizontal axis represents time. . The dashed line indicates the target value R, the solid line indicates the displacement information F,
The two-dot chain line indicates the operation amount P. Here, one pattern of the target value having a sawtooth waveform is extracted. The displacement of the electromechanical transducer 101 with respect to the target value of the sawtooth waveform having the slope a becomes like displacement information F. At this time, the target values R1 to R3 and the displacement information F1 to F3 are compared with each other at predetermined sampling timings S1 to S3 having a cycle of T in synchronization with the target value of the sawtooth waveform, and the difference is within a predetermined range. It is determined whether or not the operation amounts P1 to P3 of the electromechanical conversion element 101 are set. In S1 and S3, the operation amount is increased so that the displacement is small relative to the target value, and the operation amount is decreased in S2 because the displacement is small relative to the target value because the displacement is large. The operation amount is divided at each sampling timing, and is given by a polygonal line having inclinations a1, a2, and a3, respectively. The electromechanical transducer is driven according to the operation amount P, and the displacement at that time is detected by the displacement detecting means 108. The detected displacement information is compared with a target value at a predetermined sampling timing to determine whether the displacement information is within a predetermined range, and an operation amount is set. As described above, the operation amount is sequentially changed for each one pattern of the sawtooth wave, and the displacement is repeatedly brought close to the target value, whereby the gradient of the operation amount for linearizing the nonlinear output displacement characteristics of the electromechanical transducer 101 is obtained. Set. When the inclination of the operation amount is set, the target values R1, R at each sampling point are set based on the inclination of the operation amount.
A1 / a, a2 for each section divided by R2 and R3
/ A, a3 / a is multiplied by a non-linear correction coefficient to perform non-linear correction.

FIG. 3 is a flowchart of the general concept of the present invention. In step 301, it is determined by the system controller whether or not the nonlinear correction coefficient has been set.
The switching signal W is output from the system controller to the switching means 106 so as to select the operation amount obtained by the nonlinear correction means 105. Based on the non-linear correction coefficient stored in the non-linear correction coefficient storage means 104 in step 302,
Outputs the manipulated variable with nonlinear correction. If not set, the switching signal W is output from the system controller to the switching means 106 so as to select the operation amount obtained by the nonlinear correction coefficient generation means 103. In step 303, an operation amount for the target value having a sawtooth waveform is output, and the gradient of the operation amount is set so that the difference between the target value and the displacement information at a predetermined sampling timing falls within a predetermined range. The gradients a1, a2, and a3 of the operation amounts are stored in the nonlinear correction coefficient storage unit 104 so that a, a2 / a, and a3 / a can be generated.

FIG. 4 is a flowchart of the nonlinear correction coefficient generating means 103 of the present invention. Electromechanical transducer 10
When a sawtooth wave as a target value is output from the target value generating means 102 that generates a target value of 1 displacement, the measurement of time t starts, and a target value R is input in step 401. In step 402, the slope a1 of the operation amount from the starting point of one pattern of the sawtooth wave to the predetermined sampling timing S1
The manipulated variable P is set by multiplying the target value R by the ratio between the target value R and the gradient a of the target value. However, the initial value of the slope a1 of the operation amount is the slope a of the target value. At step 403, it is determined whether or not the predetermined sampling timing S1 has been reached based on the time t. If not, the operation amount P is output at step 414. If it has reached, at step 404, it is determined whether or not it is a predetermined sampling timing S1 based on the time t. If the predetermined sampling timing S1 has not been reached, the ratio of the gradient a2 of the manipulated variable from the predetermined sampling timings S1 to S2 to the gradient a of the target value is multiplied by the target value R in step 406 to set the manipulated variable P. You. However, the initial value of the slope a2 of the operation amount is the slope a of the target value. At step 407, it is determined based on the time t whether or not the predetermined sampling timing S2 has been reached. If not, the operation amount P is output at step 414. If you have reached
At step 408, it is determined whether or not it is a predetermined sampling timing S2 based on the time t.
2 is set. If there is no predetermined sampling timing S2, the ratio of the gradient a3 of the manipulated variable from the predetermined sampling timings S2 to S3 to the gradient a of the target value is multiplied by the target value R in step 410 to set the manipulated variable P. You. However, the initial value of the gradient a3 of the operation amount is the gradient a of the target value. In step 411, it is determined whether or not the timing is the predetermined sampling timing S3 based on the time t. In step 413, time t
Is reset, and in step 414, the manipulated variable P is output. If it is not at the predetermined sampling timing S3,
At step 414, the manipulated variable P is output. When the operation amount P is output, the process returns to the beginning, and this process is repeated until the difference between the target value and the displacement information at a predetermined sampling timing falls within a predetermined range.

FIG. 5 shows a gradient a of the operation amount P in the present invention.
It is a flowchart of 1 setting. At a predetermined sampling timing S1, the target value R1 at that time is input in step 501, and the displacement information F1 at that time is input in step 502. In step 503, it is determined whether or not the difference between the displacement information F1 and the target value R1 is equal to or smaller than a predetermined range -e (e is a positive constant). A predetermined amount r is added to the operation amount P1.
To obtain the next operation amount P11. If the difference is larger than the predetermined range -e, it is further determined in step 505 whether or not the difference between the displacement information F1 and the target value R1 is equal to or larger than the predetermined range e. A predetermined amount r is subtracted from the operation amount P1 to obtain a next operation amount P11. When the next operation amount P11 is set, the gradient a1 of the operation amount P is set by the next operation amount P11 and the cycle T in step 507, and the process exits. If it is smaller than the predetermined range e, it is determined that the non-linear correction has converged, and in step 508, the gradient a1 of the manipulated variable P is stored in the non-linear correction coefficient storage unit 104, and the process exits.

FIG. 6 shows a gradient a of the operation amount P in the present invention.
It is a flowchart of 2 setting. At a predetermined sampling timing S2, the target value R2 at that time is input in step 601 and the displacement information F2 at that time is input in step 602. In step 603, it is determined whether or not the difference between the displacement information F2 and the target value R2 is equal to or smaller than a predetermined range -e (e is a positive constant). A predetermined amount r is set to the operation amount P2.
To obtain the next operation amount P22. If the difference is larger than the predetermined range -e, it is further determined at step 605 whether or not the difference between the displacement information F2 and the target value R2 is not smaller than the predetermined range e. A predetermined amount r is subtracted from the operation amount P2, and the result is set as the next operation amount P22. When the next operation amount P22 is set, the gradient a2 of the operation amount P is set by the next operation amounts P11 and P22 and the cycle T in step 607, and the process exits. If it is smaller than the predetermined range e, it is determined that the nonlinear correction has converged, and in step 608, the gradient a2 of the manipulated variable P is stored in the nonlinear correction coefficient storage unit 104, and the process exits.

FIG. 7 shows a gradient a of the operation amount P in the present invention.
It is a flowchart of 3 setting. At a predetermined sampling timing S3, the target value R3 at that time is input in step 701, and the displacement information F3 at that time is input in step 702. In step 703, it is determined whether the difference between the displacement information F3 and the target value R3 is equal to or smaller than a predetermined range -e (e is a positive constant). A predetermined amount r is added to the operation amount P3.
To obtain the next operation amount P33. If it is larger than the predetermined range -e, it is further determined in step 705 whether or not the difference between the displacement information F3 and the target value R3 is larger than a predetermined range e. A predetermined amount r is subtracted from the operation amount P3 to obtain a next operation amount P33. When the next operation amount P33 is set, the gradient a3 of the operation amount P is set by the next operation amounts P22 and P33 and the cycle T in step 707, and the process exits. If it is smaller than the predetermined range e, it is determined that the nonlinear correction has converged, and in step 708, the gradient a3 of the manipulated variable P is stored in the nonlinear correction coefficient storage unit 104, and the process exits.

FIG. 8 is a flowchart of the nonlinear correction means 105 of the present invention. In step 800, the slopes a1, a2, and a3 of the operation amounts are stored in the nonlinear correction coefficient storage unit 104.
Is input, and a target value R and displacement information F are input in step 801. In step 802, the difference between the target value R and the displacement information F is compared with R1.
To the difference between the target value R and the displacement information F, the nonlinear correction coefficient a1 / a
Is multiplied to set the operation amount P. If not, the difference between the target value R and the displacement information F is compared with R2 in step 804, and if not, step 805
The nonlinear correction coefficient a2 / a to the difference between the target value R and the displacement information F.
Is multiplied to set the operation amount P. If it is not less than R2, the operation amount P is set in step 806 by multiplying the difference between the target value R and the displacement information F by the nonlinear correction coefficient a3 / a. When the operation amount P is set, the operation amount P is output in step 807, and the process exits.

As described above, according to the present embodiment, more accurate control can be performed more easily by performing non-linear correction on the electromechanical transducer having the non-linear displacement characteristic.

The sampling timings S1 to S3
Is a sampling timing of a constant period T, but may be set individually within one pattern of the sawtooth wave, and it will be apparent that more accurate nonlinear correction can be achieved by further increasing the number of times of sampling. .

[0029]

As described above, the present invention provides an electromechanical transducer having an output displacement characteristic with respect to an input voltage having a nonlinear displacement characteristic, a target value generating means for generating a target value of the displacement of the electromechanical transducer, The output displacement characteristic with respect to the target value of the mechanical conversion element is linearly corrected to operate the electromechanical conversion element.
Before setting the nonlinear correction coefficient, which is the slope of the crop
Operating amount of the electromechanical transducer based on the nonlinear correction coefficient
, A nonlinear correction coefficient storage means for storing the nonlinear correction coefficient generated by the nonlinear correction coefficient generation means, and a target value based on the nonlinear correction coefficient stored in the nonlinear correction coefficient storage means. A non-linear correction means for non-linearly correcting the operation amount, a switching means for switching between an operation amount obtained by the non-linear correction coefficient generation means and an operation amount obtained by the non-linear correction means, and an electromechanical conversion element according to the operation amount switched by the switching means. A non-linear correction coefficient generating unit that outputs a periodic sawtooth wave target value and displacement information obtained from the displacement detecting unit; and sampled multiple times in the period, to set the non-linear correction coefficient so that a difference between the target value and the displacement information is within a predetermined range, cut conversion The means selects the operation amount obtained from the nonlinear correction coefficient generation means until the nonlinear correction coefficient is set, and selects the operation amount obtained from the nonlinear correction means after the setting. Since the nonlinear displacement characteristics of the conversion element can be automatically reduced, more accurate control of the target value can be performed more easily.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a relationship among a target value R of displacement of the electromechanical transducer 101, displacement information F, and an operation amount P in the nonlinear correction means 105 according to one embodiment of the present invention.

FIG. 3 is a flowchart of a general concept of an embodiment of the present invention.

FIG. 4 shows a non-linear correction coefficient generating means 1 according to an embodiment of the present invention.
03 flowchart

FIG. 5 shows a gradient a1 of the operation amount P in one embodiment of the present invention.
Setting flowchart

FIG. 6 shows a gradient a2 of the operation amount P in one embodiment of the present invention.
Setting flowchart

FIG. 7 shows a gradient a3 of the operation amount P in one embodiment of the present invention.
Setting flowchart

FIG. 8 is a flowchart of the non-linear correction means according to one embodiment of the present invention;

FIG. 9 is a diagram showing a relationship between a scanning locus of a reproducing head (not shown) and a recording track in a two-head helical scan type VTR.

FIG. 10 is a diagram showing a relationship between a target value of displacement of an electromechanical transducer and displacement information of a driven electromechanical transducer.

FIG. 11 is a block diagram showing a configuration of a conventional controller for an electromechanical transducer having nonlinear displacement characteristics.

FIG. 12 is a diagram showing a relationship between applied voltage and displacement of an electromechanical transducer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Electromechanical conversion element 102 Target value generation means 103 Nonlinear correction coefficient generation means 104 Nonlinear correction coefficient storage means 105 Nonlinear correction means 106 Switching means 107 Driving means 108 Displacement detection means

Claims (1)

(57) [Claims] 1. An electromechanical transducer having an output displacement characteristic with respect to an input voltage having a non-linear displacement characteristic, a target value generating means for generating a target value of displacement of the electromechanical transducer, and a target value of the electromechanical transducer. The output displacement characteristic with respect to is linearly corrected to obtain the inclination of the operation amount of the electromechanical transducer.
A non-linear correction coefficient, and the set non-linear correction coefficient
A non-linear correction coefficient generation unit that calculates an operation amount of the electromechanical conversion element based on a number, a non-linear correction coefficient storage unit that stores a non-linear correction coefficient generated by the non-linear correction coefficient generation unit, Operating the electromechanical transducer based on the non-linear correction coefficient stored in the non-linear correction coefficient storage means.
Non-linear correction means for calculating the amount of operation, switching means for switching between the operation amount obtained by the non-linear correction coefficient generation means and the operation amount obtained by the non-linear correction means, and the operation amount switched by the switching means driving means for driving the electromechanical transducer, comprising a displacement detector for detecting the displacement of the electromechanical transducer, the nonlinear correction coefficient generating means, periodic sawtooth wave target value and the displacement detection the displacement information obtained from the means by sampled multiple times within one period, the difference between the target value and the displacement information is set to the non-linear correction coefficient to be within a predetermined range, said switching means, said Until the non-linear correction coefficient is set, the operation amount obtained by the non-linear correction coefficient generation means is selected, and after the setting, the operation amount is obtained by the non-linear correction means. Control device for an electromechanical transducer having a non-linear displacement characteristic and selects the work amount.