JPH07210249A - Digital servo device - Google Patents

Abstract

PURPOSE:To attain the digital servo control with substantially high resolution and high accuracy while using a drive information detector such as an encoder not so high in resolution. CONSTITUTION:A drive information detector 2 outputs the two-phase pulse signals AS and BS which have phases different from each other by 90 deg. in accordance with the drive value of a drive source 1 that moves a controlled system. Meanwhile a 4-multiple circuit 4 detects the rise/fall edges of both signals AS and BS and outputs a 4-multiple signal ES. Then a position detecting part 9 generates the position information based on the signal ES, and a 4-multiple signal cycle detecting part 5 detects the cycle of the signal ES. Furthermore a correction control means 8 corrects the interval of the signal ES and corrects the position and velocity information to the source 1 based on the positional information generated at the part 9 and the 4-multiple signal interval correction value stored previously in a storage means 10 or 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a read head (optical head or magnetic head) of an ODD (optical disk device) or an HDD (magnetic disk device), or a driving unit of a robot, a scanner, etc. The present invention relates to a digital servo device for a control target that requires accurate positioning control.

[0002]

2. Description of the Related Art Conventionally, as a digital servo device of this type, for example, Japanese Patent Publication No. 3-27924 (Japanese Patent Laid-Open No. 58-24 / 1983).
-207102).
This is to obtain the current position information of the object to be controlled, compare this position information with preset reference position information, and give a command so that the difference approaches zero. The generated sawtooth wave signal is corrected and added to the position information as a position insertion element, and calculation for eliminating the influence of each slit width of the encoder is performed.

More specifically, a motor for moving an object, and a drive information detection detector (encoder) for converting and outputting each pulse train for each drive direction and drive amount of the motor.
And a movement information counter that counts each pulse train output from this encoder and outputs the count value as movement information of the object, and a sawtooth wave that generates a sawtooth wave signal between each pulse of each pulse train output from the encoder. The generation circuit and the movement information from the movement information counter are taken in at regular intervals to obtain the current position information of the object and compared with preset reference position information so that the difference approaches zero. In a configuration in which a program control arithmetic control circuit that generates each information for determining the drive amount is provided, the encoder has a moving slit and a fixed slit that move in accordance with the movement of the motor, and these movements are well known. It is configured as an optical encoder that receives the amount of light passing through the slit and the fixed slit and converts it into each pulse train for each drive direction and drive amount of the motor. And, in the information to determine the driving amount calculation control circuit, in which the user is encouraged to correct the effects of the slit width of the moving slit and fixed slit in the encoder and the additional correction sawtooth wave information as positional insertion information.
Here, the signal output from the encoder will be specifically described. For example, the encoder outputs a triangular wave signal composed of an A phase and a B phase, which represent the rotation direction and the rotation amount of the DC motor and have a phase difference of 90 °. The triangular wave signal is applied to the direction discriminating circuit to detect the phase difference, thereby discriminating the rotation direction of the motor and detecting the rotation amount from the wave number of the triangular wave per unit time.

[0004]

In such a digital servo apparatus, in order to improve the accuracy of position and speed, it is necessary to increase the resolution of the drive information detector, specifically, the encoder. With the improvement of the resolution, the cost of the drive information detector increases.

In view of the above, it is an object of the present invention to provide a digital servo device capable of improving the accuracy of position and speed under a low cost structure using a drive information detector having a coarse resolution. To do.

[0006]

According to a first aspect of the present invention, there is provided a drive source for moving a controlled object, and drive information for outputting a two-phase pulse signal having a 90 ° phase difference depending on the drive amount of the drive source. A detector, a 4 times multiplication circuit for detecting rising and falling edges of these pulse signals and outputting a 4 times multiplication signal, a position detection section for generating position information based on the 4 times multiplication signal, and the 4 times multiplication signal The 4 × signal period detection unit for detecting the period of the, the storage unit, the position information of the position detection unit, and the 4 × signal interval correction value stored in advance in the storage unit to correct the 4 × signal interval. Then, it is constituted by a correction control means for correcting the position information and the speed information for the drive source.

According to a second aspect of the present invention, a drive source for moving the controlled object, a drive information detector for outputting two-phase pulse signals having different 90 ° phases according to the drive amount of the drive source, and position information. A position detection unit that generates a 4x signal that detects the rising and falling edges of these pulse signals and outputs a 4x signal, and a position detection part that generates position information based on this 4x signal. A 4x signal cycle detection unit for detecting the cycle of the 4x signal, a storage means, an edge detection means for detecting an edge number of the 4x signal, an edge number detected by the edge detection means and the storage means in advance. The correction control means corrects the interval of the quadruple signal based on the stored quadruple signal interval correction value and the position information and speed information for the drive source.

According to a third aspect of the present invention, with respect to the configuration of the second aspect of the invention, the edge detecting means is a 2-bit counter for sequentially counting quadrupled signals.

According to the inventions of claims 4, 5, and 6, in addition to the configurations of the inventions of claims 1, 2 and 3, the cycle of a two-phase pulse signal output from the drive information detector is detected. A pulse signal cycle detecting unit is provided, and a correction control unit that obtains a 4 × signal interval correction value corresponding to the edge number of the 4 × signal in advance based on the output of the pulse signal cycle detecting unit and stores it in the storage unit.

[0010]

According to the first aspect of the present invention, the phase difference of 90 ° output from the drive information detecting section is different according to the drive amount.
With respect to the phase pulse signal, since the rising and falling edges are detected by the quadruple multiplication circuit and a quadruple multiplication signal is output, and used for detection of position information and speed information in the position detection unit and quadruple signal cycle detection unit, The resolution is four times the resolution of the drive information detector. At this time, the quadruple signal includes an error caused by a sensor characteristic in the drive information detection unit, a phase shift between two phases, a processing circuit for converting an analog signal into a rectangular wave as a pulse signal, and the like. Based on the stored 4 × signal interval correction value, this 4
Since the interval of the multiplied signal is corrected and used for the correction of the position information and the speed information, a highly accurate digital servo which is not affected by the error contained in the multiplied signal becomes possible.

The invention described in claim 2 is basically the same as that according to the invention described in claim 1, but in particular, it has edge detection means for detecting the edge number of the quadrupled signal, and detects the edge number. Since the interval of the 4x signal is corrected based on the edge number and the preset 4x signal interval correction value, it is only necessary to store 4 kinds of 4x signal interval correction values, and the storage of the storage means. The capacity may be small, resulting in a lower cost configuration.

According to the third aspect of the invention, since the 2-bit counter is used as the edge detecting means for detecting the edge number of the quadruple-multiplied signal, the edge number can be easily detected without any calculation processing. The burden on the software can be reduced, and the cost can be further reduced.

In the inventions according to claims 4, 5, and 6,
A pulse signal cycle detection unit for detecting the cycle of the two-phase pulse signal output from the drive information detector is provided, and this detection output is not affected by an error caused by a quadruple multiplication circuit or the like Since the correction value is used for calculating the correction value, it is possible to cope with the change of the error of the quadruple signal due to the change with time of the apparatus, in addition to the operation according to the corresponding inventions of claims 1, 2 and 3. .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 will be described with reference to FIGS. For example, a linear motor 1 serving as a drive source is provided by an actuator for an optical head that reciprocates linearly in the left-right direction in the figure by mounting a control target such as an optical head. A linear encoder 2 serving as a container is provided. The linear encoder 2 has a well-known configuration as shown in the above-mentioned publication, and is configured as an optical linear encoder as shown in FIG. 2 of the publication, for example. That is, a moving slit provided on the side of the linear motor 1 and two fixed slits facing the moving slit and the arrangement states of the slits differ from each other by 90 ° are provided.
The moving position information of the linear motor 1 is detected by receiving the light passing through each of these moving slits and two types of fixed slits with a light receiver for each fixed slit. Here, when the light receiving outputs of these light receivers are AS and BS, respectively, the maximum is obtained when the window of the moving slit and the window of the fixed slit are completely coincident with each other, and the windows of the respective slits are displaced from each other by 180 °. When the linear motor 1 moves, the output AS and BS have a triangular waveform. Therefore, if this is converted into a pulse signal based on a predetermined average level, these outputs AS and BS are output.
2 are pulse signals of A phase and B phase having different 90 ° phases, as shown in FIG.

A direction discriminating circuit 3 and a quadruple multiplying circuit 4 are provided which receive the A-phase and B-phase pulse signals AS and BS output from the linear encoder 2 as described above. The quadrupling circuit 4 detects the rising and falling edges of the A-phase and B-phase pulse signals AS and BS output from the linear encoder 2 as shown in FIG. 2, and detects the edges within one cycle P of these signals. 4 to generate 4 signals with number 0 to 3
It outputs the multiplied signal ES. This four multiplication circuit 4
A quadruple signal period detection unit 5 is connected to the output side of the. The quadruple signal cycle detector 5 detects the cycle of the quadruple signal ES by counting the basic clock supplied from the reference clock oscillator (OSC) 6.
The clock count number NS can be output to the CPU 8 functioning as correction control means via the data bus 7.

As is well known in the above-mentioned publications, the direction discriminating circuit 3 has a phase A output from the linear encoder 2,
The moving direction of the linear motor 1 is discriminated from the phase difference between the B-phase pulse signals AS and BS. The direction discriminating signal DS is input to the position detecting section 9 together with the 4-multiplication signal ES from the 4-multiplication circuit 4. Has been done. The position detector 9 counts the rising edges of the quadrupled signal ES sequentially and outputs the pulse count NP to the CPU to calculate the current position information X of the linear motor 1.

Further, the data bus 7 is provided with a ROM 10
And a RAM 11 are connected as storage means, and a ROM
10 or the RAM 11 stores, for example, a quadruple signal interval correction value corresponding to the position information X. Also, the C
The PU 8 carries out various kinds of arithmetic processing, etc., which will be described later, according to a program stored in the ROM 10, for example, and is responsible for a drive circuit for the linear motor 1 and other operation controls.

In such a configuration, the linear motor 1
When is driven, the linear encoder 2 outputs A-phase and B-phase pulse signals AS and BS having a 90 ° phase difference according to the movement amount (driving amount). The quadruple multiplication circuit 4 receives these pulse signals AS and BS, and outputs a quadruple multiplication signal ES to the quadruple multiplication signal cycle detection unit 5 as shown in FIG. 2 in accordance with the rising and falling edges thereof. To do. The quadruple signal cycle detector 5 counts the time from the rising edge of the quadruple signal ES to the next rising edge by using the basic clock. This clock count number N
S is input to the CPU 8 and the speed information V [m / s] is calculated based on the following formula (1) V = (P / 4) / (NS / CLK) (1) Be used for.
In the equation (1), P [m] is the encoder pitch in the linear encoder 2, and CLK [Hz] is the basic clock.

Further, pulse signals AS and B of A phase and B phase are also provided.
S is also input to the direction determination circuit 3, and the direction determination signal DS is input to the position detection unit 9. The position detector 9 receives the quadruple signal ES together with the direction discrimination signal DS
The rising edges of the multiplied signal ES are counted. This pulse count number NP is input to the CPU 8 and the position information X [m based on the following equation (2) X = (P / 4) × NP (2) ] Is used for calculation.

Here, the quadruple-multiplied signal ES has substantially four times the resolution of the linear encoder 2 having a coarse resolution, but the sensor characteristics of the light receiver in the linear encoder 2, Including the phase shift between the A phase and the B phase, and the error (interval error of the quadrupled signal ES) caused by the processing circuit for converting the analog signal output from the photodetector into the rectangular wave signal output from the pulse signals AS and BS. There is. Therefore,
With such arithmetic control using the 4 × signal ES as it is, highly accurate digital servo control cannot be ensured. Therefore, in this embodiment, the quadruple signal interval correction value ΔP _X (X) corresponding to the position information X is stored in the ROM 10 or the RAM 11 in advance, and the CPU 8 causes the following expression (3) (4) X ′ = X + ΔP _X (X) ………………………………………… (3) V ′ = {P / 4 + ΔP _X (X)} / (NS / CLK) ………… (4) Then, the correction processing is performed so that the position information X and the speed information V become the corrected position information X '[m] and the corrected speed information V' [m / s], respectively. Then, the CPU 8 carries out a positioning control calculation for the drive circuit of the linear motor 1 using the corrected position information X ′ and the corrected speed information V ′.

Therefore, according to the present embodiment, the quadruple multiplication circuit 4 obtains a quadruple multiplication signal ES having a quadruple resolution on the basis of the A-phase and B-phase pulse signals AS and BS by the linear encoder 2, and the quadruple multiplication is performed. The error component of the signal ES is corrected from the relationship between the quadruple signal interval correction value ΔP _X (X) and the position information X,
Since the position information X and the speed information V are used for correction, it is possible to perform high-resolution and high-precision digital servo control without using a linear encoder 2 having such high resolution.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIG. The same parts as those shown in the above-mentioned embodiments are designated by the same reference numerals (the same applies to the following embodiments). Basically, the position information X and the speed information V are calculated under the same operation as that of the above-mentioned embodiment. However, since the position information X and the speed information V include an error, each of the quadruple multiplication signal ES is calculated. Four types of edge numbers EN from 0 to 3 are attached to rising edges (see FIG. 2), edge detection means for detecting these edge numbers EN is provided, and arithmetic processing described later is performed according to the edge numbers. The position information X and the speed information V are corrected.

Here, the edge detection means of this embodiment is CP
It is constructed on the software of U8, and the detecting operation of the edge number EN will be described with reference to the flowchart shown in FIG. First, each time the CPU 8 reads the pulse count number NP from the position detection unit 9 (that is, every control operation cycle), the new pulse count number NP _n is compared with the pulse count number NP _n-1 one cycle before. , The difference ΔN
It is determined by P whether the linear motor 1 has moved, and if it has moved, a value obtained by adding the difference ΔNP to the edge number EN up to that point is set as a new edge number EN. However, at 1 pitch P, the edge number repeats 0 to 3 and 4
The edge number EN of the addition result is not exceeded.
Is smaller than 4, it is left as it is, and when it is 4 or more, a value obtained by subtracting 4 is set as the edge number EN.

On the other hand, four types of 4 × signal interval correction values ΔP _EN (EN) [m] corresponding to the edge number EN are stored in the ROM 10 or the RAM 11 in advance, and as described above, When the edge number EN of ES is detected, the CPU 8 uses the edge number EN and the quadruple signal interval correction value ΔP _EN (EN) stored in advance, and the following equations (5) and (6) X ′ = X + ΔP _EN (EN) …………………………………… (5) V ′ = {P / 4 + ΔP _EN (EN)} / (NS / CLK) ……… (6) is calculated. , The position information X and the speed information V become the corrected position information X ′ and the corrected speed information V ′, respectively. Then, the CPU 8 carries out a positioning control calculation for the drive circuit of the linear motor 1 using the corrected position information X ′ and the corrected speed information V ′.

Therefore, also in the case of this embodiment, as in the case of the above embodiment, a quadruple signal having a quadruple resolution in the quadrupling circuit 4 is generated based on the pulse signals AS and BS of the A phase and B phase by the linear encoder 2. ES is obtained, and the possible error of the 4 × signal ES is corrected from the relation between the 4 × signal interval correction value ΔP _EN (EN) and the edge number EN, and is used for the correction of the position information X and the speed information V. Therefore, it is possible to perform digital servo control with high resolution and high accuracy without using a linear encoder 2 having a high resolution. In particular, since the edge number EN of the 4 × signal ES is used, it is sufficient to store four types of 4 × signal interval correction values ΔP _EN (EN) in the ROM 10 or the RAM 11, and the 4 × signal interval correction value. The memory capacity required for the digital servo device can be reduced, and the cost can be reduced.

An embodiment of the invention described in claim 3 will be described with reference to FIG. In the present embodiment, the 2-bit counter 12 is provided as the edge detecting means instead of the edge detecting means of the software configuration of the above embodiment. The input side of the 2-bit counter 12 is a quadruple multiplication circuit 4 and a direction determination circuit 3.
Is connected to the CPU and the output side is connected to the CPU via the data bus 7.
8 is connected. In addition, in the case of the present embodiment as well,
Four types of 4-multiplication signal interval correction values ΔP _EN (EN) [m] corresponding to the third edge number EN are stored in the ROM 10 or the RAM 11 in advance.

In such a configuration, the 2-bit counter 12 sequentially changes its count value each time the 4-multiplied signal ES is input, so that the edge numbers EN of 0 to 3 correspond to the count value. Is detected (the relative edge number is reversed depending on the direction determination signal DS (that is, the moving direction) determined by the direction determination circuit 3). Therefore, the CPU 8 reads the edge number EN from the 2-bit counter 12 for each control cycle, and similarly to the case of the above embodiment, the quadruple signal interval correction value ΔP _EN (EN corresponding to the prestored corresponding edge number EN. ) Is used to perform the calculation of the above equations (5) and (6), and the correction processing is performed so that the position information X and the speed information V become the corrected position information X ′ and the corrected speed information V ′, respectively. Then, the CPU 8 carries out a positioning control calculation for the drive circuit of the linear motor 1 using the corrected position information X ′ and the corrected speed information V ′.

Therefore, even in the case of this embodiment, the same effect as that of the above embodiment can be obtained.
Since the bit counter 12 is used, unlike the software configuration, the operation for detecting the edge number EN is not required, the load on the software can be reduced, and the cost can be further reduced. .

An embodiment of the invention described in claim 4 will be described with reference to FIGS. In the present embodiment, in addition to the configuration shown in FIG. 1 corresponding to the invention described in claim 1, one of the two-phase pulse signals AS and BS output from the linear encoder 2 (in the illustrated example, the pulse signal AS is shown). ) Is provided with a pulse signal period detection unit 13, and the clock signal count number NA corresponding to the period signal detected by the pulse signal period detection unit 13 is used as the position information X corresponding quadruple signal interval correction value ΔP _X. This is taken into the CPU 8 for calculating (X).

That is, the present embodiment is provided with the pulse signal period detection unit 13 for calculating the quadruple signal interval correction value ΔP _X (X) corresponding to the position information X, and the A phase pulse signal. When AS is input to the pulse signal period detector 13, the time from the rising edge to the next rising edge is detected by counting the basic clock CLK as shown in FIG. Such a pulse signal period detection unit 1
The clock count number NA detected in 3 is not affected by the phase shift between the A phase and the B phase or the error generated by the quadruple multiplication circuit 4. A clock count number NA which is not affected by such errors is fetched into the CPU 8 and the following formula (7) V _NA = P / (NA / CLK) ……………………………… (7) Calculate velocity information V _NA . The CPU 8 performs constant speed control for the linear motor 1 using the speed information V _NA calculated in this way. However, if the speed becomes too low, the speed information decreases, so the target speed in this case is a speed at which sufficient speed information V _NA is obtained.

The number of clock counts NA (X) in the pulse signal period detector 13 and the number of clock counts counted in the quadruple signal period detector 5 corresponding to the position information X when the constant speed is controlled in this way. NS (X), NS (X-
1), NS (X-2), NS (X-3) and equation (8) [ΔP _X (Xi) = {(P / NA (X)) / 4} -NS (Xi)] _{i = 0, 1,2,3} …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… After the correction (ΔP)
_X (X), ΔP _X (X-1), ΔP _X (X-2), and ΔP _X (X-3) are calculated. Similarly, X = [4k−1] _{k = 0,1,2-n} is changed, and a quadruple signal interval correction value ΔP _X (X) corresponding to all position information X is calculated, and the ROM 10 or It is stored in the RAM 11 in advance.

Such a 4 × signal interval correction value ΔP _X (X)
The correction of the position information X and the speed information V and the control thereafter are the same as those in the above-described embodiment.

Therefore, according to the present embodiment, in addition to the effect of the embodiment corresponding to the invention described in claim 1, the pulse signal period detection unit 13 is provided and the clock count number NA which is the output thereof.
Since the quadruple signal interval correction value ΔP _X (X) corresponding to the position information X is obtained in advance, the influence of the phase shift between the A phase and the B phase and the error caused by the quadruple circuit 4 etc. Since the correction is based on the pulse period without any error, it is possible to deal with the change in the error of the quadruple signal ES due to the change with time of the device.

An embodiment of the invention described in claim 5 will be described with reference to FIG. The present embodiment can also be achieved by a configuration similar to the case shown in FIG. 5, but as described in the embodiment corresponding to the invention of claim 2, instead of the position information X, The edge number detected by the edge detecting means of the software configuration is associated with the quadruple signal interval correction value.

First, as in the above embodiment, the clock count number N detected by the pulse signal period detector 13
Using A (pulse period P), constant speed control based on the speed information V _NA as shown in equation (7) is performed. Under such constant speed control, the clock count number NA in the pulse signal cycle detection unit 13 and the count number NS four times corresponding to the edge number EN of the 4 × signal counted in the 4 × signal period detection unit 5 (0), NS (1), NS (2), NS (3) and equation (9) [ΔP _EN (EN) = {(P / NA) / 4} -NS (EN)] _{EN = 0,1 2,3} based on a ....................................... (9), CPU 8 is quadrupled signal interval correction value [Delta] P _EN
(EN) is calculated and stored in the ROM 10 or the RAM 11 in advance.

Such a 4 × signal interval correction value ΔP _EN (E
The correction of the position information X and the speed information V using N) and the subsequent control are the same as in the above-described embodiment.

Therefore, according to the present embodiment, in addition to the effect of the embodiment corresponding to the invention described in claim 2, the pulse signal period detection unit 13 is provided and the clock count number NA which is the output thereof is provided.
Since the 4 × signal interval correction value ΔP _EN (EN) corresponding to the edge number EN is obtained in advance by using, the influence of an error caused by the phase shift between the A phase and the B phase and the 4 × circuit 4 etc. Since the correction is based on the pulse period without any error, it is possible to deal with the change in the error of the quadruple signal ES due to the change with time of the device.

An embodiment of the invention described in claim 6 will be described with reference to FIG. In the present embodiment, in addition to the configuration of the embodiment corresponding to the invention described in claim 4 (FIG. 5), as in the embodiment corresponding to the invention described in claim 3, the 2-bit counter 12 is provided as the edge detecting means. . Therefore, the 2-bit counter 12 sequentially detects the edge number EN of the quadrupled signal ES, as in the case described with reference to FIG. Further, similarly to the case described in the above embodiment (by the expression (9)), the quadruple signal interval correction value ΔP _EN (EN) corresponding to the detected edge number EN is calculated and stored in the ROM 10 or the RAM 11 in advance. I'll do it. Such a 4 × signal interval correction value ΔP
The correction of the position information X and the speed information V using _EN (EN) and the subsequent control are the same as those in the above-described embodiment.

Therefore, according to this embodiment, the third and fourth aspects are provided.
And the effects of the embodiment corresponding to the invention described in 5 are also provided.

[0040]

According to the first aspect of the invention, the drive source for moving the controlled object and the drive amount of the drive source are set to 9
A drive information detector that outputs two-phase pulse signals having different 0 ° phases, a four-time multiplication circuit that detects rising and falling edges of these pulse signals and outputs a four-time multiplication signal, and a four-time multiplication signal A position detection unit that generates position information based on the above, a 4 × signal cycle detection unit that detects the cycle of the 4 × signal, a storage unit, position information of the position detection unit, and a 4 × prestored in this storage unit. And a correction control means for correcting the position information and the speed information for the driving source by correcting the interval of the quadruple-multiplied signal based on the signal interval correction value. Since the influence of the error contained in the 4 × signal is corrected by the 4 × signal interval correction value under the control with the resolution of 4 × that of the driving information detector, the resolution is not so high. It is possible to perform the highly accurate digital servo inexpensive configuration using.

The case of the invention according to claim 2 is basically the same as the case of the invention according to claim 1,
In particular, the edge detection means for detecting the edge number of the 4 × signal is provided, and the interval of the 4 × signal is corrected on the basis of the detected edge number and the previously stored 4 × signal interval correction value. Only four types of 4 × signal interval correction values need to be stored, the storage capacity of the storage means can be small, and a lower cost configuration can be achieved.

Further, according to the invention of claim 3, 4
Since the 2-bit counter is used as the edge detecting means for detecting the edge number of the multiplied signal, the edge number can be easily detected without the need for arithmetic processing, thus reducing the load on the software and further reducing the cost. be able to.

According to the fourth, fifth, and sixth aspects of the present invention, a pulse signal cycle detection unit for detecting the cycle of the two-phase pulse signals output from the drive information detector is provided, which is caused by the quadruple multiplication circuit and the like. This detection output, which is not affected by the error generated by the above, is used to calculate the quadruple signal interval correction value. Therefore, in addition to the effects of the corresponding inventions according to claims 1, 2 and 3, the aging of the device It is possible to cope with a change in the error of the quadruple signal due to a change or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the invention described in claim 1.

FIG. 2 is a signal waveform diagram thereof.

FIG. 3 is a flowchart of an edge number detection process showing an embodiment of the invention described in claim 2;

FIG. 4 is a block diagram showing an embodiment of the invention described in claim 3;

FIG. 5 is a block diagram showing an embodiment of the invention described in claim 4.

FIG. 6 is a signal waveform diagram for explaining the correction value calculation process.

FIG. 7 is a signal waveform diagram for explaining a correction value calculation process according to an embodiment of the present invention.

FIG. 8 is a block diagram showing an embodiment of the invention according to claim 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive source including controlled object 2 Drive information detector 4 4 multiplication circuit 5 4 multiplication signal cycle detection section 8 Correction control means 9 Position detection section 10, 11 Storage means 12 2-bit counter, Edge detection means 13 Pulse signal cycle detection section

Claims (6)

[Claims] 1. A drive source for moving a controlled object, a drive information detector for outputting a two-phase pulse signal having a phase difference of 90 ° according to the drive amount of the drive source, and the rising and rising edges of these pulse signals. A 4 × circuit for detecting a down edge and outputting a 4 × signal, a position detector for generating position information based on the 4 × signal, and a 4 × signal period detector for detecting the cycle of the 4 × signal. A storage unit, position information of the position detection unit, and a quadruple signal interval correction value stored in advance in the storage unit to correct the quadruple signal interval, and position information and speed information for the drive source. A digital servo device comprising: a correction control unit that corrects 2. A drive source for moving a controlled object, a drive information detector for outputting a two-phase pulse signal having a phase difference of 90 ° according to the drive amount of the drive source, and a position detector for generating position information. A 4 × circuit for detecting the rising and falling edges of these pulse signals and outputting a 4 × signal, a position detector for generating position information based on the 4 × signal, and a cycle of the 4 × signal. Quadruple signal period detecting section for detecting the frequency, a storing means, an edge detecting means for detecting an edge number of the quadruple multiplying signal, an edge number detected by the edge detecting means and a quadruple multiplying signal stored in advance in the storing means. A digital servo apparatus comprising: a correction control unit that corrects the position of the drive source and the speed information by correcting the interval of the quadruple signal based on the interval correction value. 3. The digital servo device according to claim 2, wherein the edge detecting means is a 2-bit counter for sequentially counting the quadruple-multiplied signals. 4. A pulse signal cycle detecting section for detecting a cycle of a two-phase pulse signal output from a drive information detector is provided, and an edge number of a quadruple multiplication signal is preliminarily corresponded to based on an output of the pulse signal cycle detecting section. 2. The digital servo apparatus according to claim 1, wherein the correction control means obtains a quadruple signal interval correction value to be stored and stores it in the storage means. 5. A pulse signal cycle detector for detecting the cycle of a two-phase pulse signal output from the drive information detector is provided, and the edge number of the quadruple signal is preliminarily corresponded to based on the output of this pulse signal cycle detector. 3. The digital servo device according to claim 2, wherein the correction control means obtains a quadruple signal interval correction value to be stored and stores it in the storage means. 6. A pulse signal cycle detector for detecting the cycle of a two-phase pulse signal output from the drive information detector is provided, and the edge number of the quadruple signal is preliminarily corresponded to based on the output of this pulse signal cycle detector. 4. The digital servo device according to claim 3, wherein the correction control means obtains a quadruple signal interval correction value to be stored and stores it in the storage means.