JP2001330475A - Encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encorder wherein a coversion error is reduced and the accuracy of position data is high. SOLUTION: The encoder is equipped with an arithmetic means for obtaining at least one dummy sine wave signal c1 obtained by multiplying a dummy sine wave signal (a), which is formed by an original signal forming means 11 accompanied by a change of a position, and a dummy sine wave signal (b), which has a phase difference with respect to the dummy sine wave signal (a), by a coefficient and adding or subtracting both signals multiplied by the coefficient, a selection means 13 for selecting either one of the dummy sine wave signals (a), (b), c1 and a position data forming means 14 for converting the change of the dummy sine wave signal selected by the selection means 13 to position data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplication type encoder used as a rotational position sensor or a linear scale position sensor.

[0002]

2. Description of the Related Art Generally, an encoder generates a pulse signal, a pseudo sine wave signal, and the like according to a position change, and obtains position information based on the signal. In recent years, however, the encoder has multiplied the pseudo sine wave signal to obtain a high resolution. It is trying to make it.

An example of a conventional encoder will be described below with reference to the drawings.

[0004] In FIG. 8, in the conventional multiplying encoder, the original signal generating means 81 changes the position of the pseudo sine wave signal a with the pseudo sine wave signal a, and the pseudo sine wave signal a has a phase difference of about 90 °. A wave signal b is generated.

[0005] Next, as shown in FIG. 9, the selection means 83 selects one of the pseudo sine wave signals a and b which has a relatively good linearity, and selects the signal selected by the position information generation means 84. The change was converted to location information.

[0006]

However, in the above-mentioned conventional encoder, the selection means has two options.
In some cases, there is only one type, and a portion of the pseudo sine wave signal having poor linearity must be selected. In this case, there is a problem that the accuracy of the converted position information deteriorates.

When the position information is converted by the position information generating means using an inverse sine function or the like in order to increase the conversion accuracy of the portion having poor linearity, the pseudo sine wave signal is converted from the ideal sine wave signal. There has been a problem that a conversion error occurs due to the deviation, and the accuracy of the position information deteriorates.

The present invention solves the above-mentioned problems of the prior art. In particular, the present invention provides an encoder that converts a highly linear portion of a pseudo sine wave signal into position information, has a small conversion error, and has high accuracy of position information. The purpose is to do.

[0009]

In order to solve this problem, the present invention provides a pseudo sine wave signal a generated by a change in position by an original signal generating means, and the pseudo sine wave signal a and the position of the pseudo sine wave signal a. In an encoder that obtains position information based on a pseudo sine wave signal b having a phase difference, the pseudo sine wave signal a and the pseudo sine wave signal b each have at least different phases obtained by multiplying or subtracting by a coefficient. Calculating means for obtaining one pseudo sine wave signal c1, selecting means for selecting any one of the pseudo sine wave signals a, b, c1, and positional information indicating a change in the pseudo sine wave signal selected by the selecting means And position information generating means for converting the information into

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve this problem, the present invention relates to a pseudo sine wave signal a generated by a change in position by an original signal generation means, and a phase difference between the pseudo sine wave signal a and the pseudo sine wave signal a. In the encoder for obtaining position information based on the pseudo sine wave signal b, at least one pseudo phase having a different phase obtained by adding or subtracting the pseudo sine wave signal a and the pseudo sine wave signal b by respective coefficients. Calculating means for obtaining a sine wave signal c1, and the pseudo sine wave signals a, b,
Since the encoder including the selecting unit for selecting any one of the signals c1 and the position information generating unit for converting a change in the pseudo sine wave signal selected by the selecting unit into position information, the encoder includes the calculating unit. Since a pseudo sine wave signal having a different phase is generated and a signal having relatively high linearity can be selected because of the provision of the selection means, the position information generation means for converting a change in the pseudo sine wave signal into position information can be used. This has the effect that highly accurate position information can be obtained.

The selecting means compares the pseudo sine wave signals a, b, and c1 continuously or at regular sampling intervals, and selects the center of the maximum value and the minimum value of any one of the pseudo sine wave signals. 2. The encoder according to claim 1, wherein the pseudo sine wave signal closest to the value is selected. Among the signals, the pseudo sine wave closest to the center value between the maximum value and the minimum value of each of the pseudo sine wave signals. By selecting a wave signal, a signal with good linearity can be selected,
This has the effect that highly accurate position information can be obtained after conversion.

Further, position information is obtained based on a pseudo sine wave signal a generated by the original signal generation means in accordance with a change in position and a pseudo sine wave signal b having a phase difference from the pseudo sine wave signal a. An arithmetic unit for obtaining at least one pseudo sine wave signal c1 having a different phase by adding or subtracting the pseudo sine wave signal a and the pseudo sine wave signal b by a coefficient respectively; Weighting means for multiplying each of the wave signals a, b and c1 by a weighting coefficient, and position information generating means for converting a change in the signal obtained as a result of the calculation by the weighting means into position information; The encoder provided has a weight calculation means for calculating each of the pseudo sine wave signals a, b, and c1 by multiplying each signal by a weight coefficient.
There is no switching point due to signal selection, that is, a discontinuous point, and the position information generating means for converting a change in a signal into position information does not need to perform signal processing paying attention to the discontinuous point.

In the weighting means, the weighting coefficient for the pseudo sine wave signals a, b, c1 is an increasing function of the absolute value of the pseudo sine wave signal having a large absolute value in a section having good linearity. In this encoder, highly accurate position information can be obtained after conversion by weighting a portion having good linearity.

In addition, at least one of immediately before and immediately after the arithmetic means is provided with a signal correcting means, and pseudo sine wave signals a, b, c
The encoder according to any one of claims 1 and 3, wherein at least one of the first, second, and third corrections is performed such as an amplitude correction, a DC correction, and a phase correction. Each of the signals c1 has the same amplitude and DC value and is different only in the phase. The influence of the difference between the selected pseudo sine wave signals is less likely to appear in the converted position information, and highly accurate position information can be obtained. Has the effect of being

The encoder according to claim 1 or 3, further comprising A / D conversion means for performing subsequent signal processing by a digital amount immediately after the original signal generation means. Since the subsequent signal processing can be performed by a digital amount by the A / D conversion means provided immediately after the above, the subsequent signal processing becomes easy.

[0016]

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

(Embodiment 1) In FIG. 1, reference numeral 11 denotes an original signal generating means for generating a pseudo sine wave signal b having a phase difference of about 90 ° from the pseudo sine wave signal a, and 12 an original signal generating means 11 Two-phase pseudo sine wave signals a and b
Calculating means for obtaining pseudo sine wave signals c1 and c2 having different phases obtained by weighting addition or subtraction of the sine wave signals, and comparing the pseudo sine wave signals a, b, c1 and c2 with each other, Selection means 14 for selecting the pseudo sine wave signal closest to the median value of the signal is position information generating means for converting a change in the pseudo sine wave signal selected by the selection means 13 into position information.

Next, their operation will be described with reference to the drawings.

First, the pseudo sine waves a and b generated by the original signal generation means 11 are set as a = sin θ b = sin (θ + 90 °), and the pseudo sine wave signals c 1 and c 2 generated by the calculation means 12 are c1 = (a + b) / √2 = sin (θ + 45 °) Let c2 = (ab) / √2 = sin (θ + 135 °). Since these signals have good linearity at the center value between the maximum value and the minimum value, that is, the portion close to the median value, the selecting means 13 changes the pseudo sine wave signals a, b, c1, and c2 to the most median value. Select a close signal. In FIG. 2, in the position section, the selection signal: a in the position section, the selection signal: c2 in the position section, the selection signal: b, in the position section, the selection signal: c1, in the position section, the selection signal: a, in the position section, the selection signal: Signal: c2 In the position section, select signal: b In the position section, select signal: c1 In the position section, select signal: a. As these selection switching signals, for example, a signal represented by an absolute value of a difference from a median value of each signal is generated in advance, and these are compared by a comparator or the like, and a, b, c
A signal having the smallest absolute value of each of 1, 1 and c2 may be selected. Then, the position information generating means 14 performs A / D conversion on these selected signals, and converts the obtained digital amount into position information using a table or the like.

As described above, in the first embodiment, two new pseudo sine wave signals are generated, a signal having good linearity is selected for every position section, and the position information generating means 14 converts the signal into position information. As a result, highly accurate position information can be obtained.

In addition, when the pseudo sine wave signal has a large deviation from the ideal sine wave signal and is close to a large triangular wave, and the triangular wave is converted into position information using a particularly good linearity portion of the signal, the accuracy is high. Location information is obtained.

As shown in FIG. 3, signal correcting means 15 and 16 are provided before and after the calculating means 12, and the signal correcting means 15 converts the pseudo sine wave signals a and b before the calculation, and the signal correcting means 16 performs the processing. If the pseudo sine wave signals c1 and c2 after the calculation are implemented to have the same amplitude in amplitude correction, the same DC value in DC correction, and the ideal phase difference in phase correction, variations in the pseudo sine wave signals a and b will occur. Even when this occurs, highly accurate position information can be obtained, which is more effective.

As shown in FIG. 4, A / D conversion means is provided immediately after the original signal generation means 11 to make the pseudo sine wave signals a and b digital quantities, and the subsequent signal processing is carried out in digital quantities. Then, the subsequent calculation becomes easy.

(Embodiment 2) In the first embodiment, the case where the selecting means 13 is used has been described. In the second embodiment, the case where the weighting calculating means 18 is used instead of the selecting means 13 will be described. As shown in FIG. 5, a weighting calculating means 18 is used. Then, as shown in FIG. 2, in the position section of each signal, the linearity of a is good and the absolute value of b is large. In the position section, the linearity of c2 is good, and the absolute value of c1 is large. In the position section, the linearity of b is good and the absolute value of a is large. In the position section, the linearity of c1 is good and the absolute value of c2 is large. In the position section, the linearity of a is good and the absolute value of b is large. In the position section, c2
And the absolute value of c1 is large. In the position section, the linearity of b is good and the absolute value of a is large. In the position section, the linearity of c1 is good and the absolute value of c2 is large.
In the position section, utilizing the fact that the linearity of a is good and the absolute value of b is large, the weighting of a is an increasing function of the absolute value of b, the weighting of c2 is an increasing function of the absolute value of c1, and the weighting of b is The increasing function of the absolute value of a, and the weighting of c1 is c2
By sending a continuous signal obtained by weighting the signals a, b, c1, and c2 to the position information generating means 14 as an increasing function of the absolute value of Can be obtained.

As shown in FIGS. 6 and 7, the effects obtained when the signal correction means 15, 16 and A / D conversion means 17 are used are as described in the first embodiment.

In this embodiment, the number of signals newly generated by the calculating means 12 is 2. However, it is sufficient that the number is 1 or more. The phase difference between the pseudo sine wave a and the pseudo sine wave b is approximately Although 90 ° is used, if the angle is other than 180 °, signals having different phases can be generated by adding and subtracting the signals. Therefore, the signal need not be 90 °. Easy.

[0027]

As apparent from the above embodiment, according to the first aspect of the present invention, a signal for interpolating between the phases of the pseudo sine wave signals a and b generated by the original signal generating means is generated. Since there is provided a selection unit for selecting a signal having the best linearity in a section for obtaining position information from the signal generated by the calculation unit, the conversion error is small, and the accuracy of the position information obtained by the position information generation unit is reduced. Can be improved.

According to the third aspect of the present invention, the weight calculation means eliminates the need for signal switching, and eliminates the need to pay special attention to discontinuous points. Obtainable.

According to the fifth aspect of the present invention, since the signal correcting means is provided, highly accurate position information can be obtained even when the pseudo sine wave signals a and b vary.

Further, according to the invention described in claim 6, A
By providing the / D conversion means, subsequent processing can be performed digitally, and highly accurate position information can be obtained more easily.

Therefore, it is possible to obtain an encoder with a small conversion error and high accuracy of position information.

[Brief description of the drawings]

FIG. 1 is a block diagram of an encoder according to a first embodiment of the present invention.

FIG. 2 is a timing chart of a pseudo sine wave signal according to the present invention.

FIG. 3 is another block diagram of the encoder according to the first embodiment of the present invention.

FIG. 4 is still another block diagram of the encoder according to the first embodiment of the present invention.

FIG. 5 is a block diagram of an encoder according to a second embodiment of the present invention.

FIG. 6 is another block diagram of an encoder according to the second embodiment of the present invention.

FIG. 7 is still another block diagram of the encoder according to the second embodiment of the present invention.

FIG. 8 is a block diagram of a conventional encoder.

FIG. 9 is a timing chart of a conventional pseudo sine wave signal.

[Explanation of symbols]

 Reference Signs List 11 original signal generating means 12 calculating means 13 selecting means 14 position information generating means 15, 16 signal correcting means 17 A / D converting means 18 weighting calculating means a, b, c1, c2 pseudo sine wave signal

Claims (6)

[Claims] 1. Position information is generated based on a pseudo sine wave signal a generated by a change in position by an original signal generation means and a pseudo sine wave signal b having a phase difference from the pseudo sine wave signal a. An encoder for obtaining at least one pseudo sine wave signal c1 having a different phase obtained by multiplying or adding the pseudo sine wave signal a and the pseudo sine wave signal b by a coefficient, respectively; An encoder comprising: a selection unit that selects any one of the sine wave signals a, b, and c1; and a position information generation unit that converts a change in the pseudo sine wave signal selected by the selection unit into position information. 2. A pseudo sine wave signal a,
2. A pseudo sine wave signal closest to a central value between a maximum value and a minimum value is selected from any one of the pseudo sine wave signals, wherein b and c1 are compared with each other continuously or at a constant sampling time. The described encoder. 3. Position information is generated based on a pseudo sine wave signal a generated by the original signal generation means with a change in position and a pseudo sine wave signal b having a phase difference from the pseudo sine wave signal a. An arithmetic unit for obtaining at least one pseudo sine wave signal c1 having a different phase by adding or subtracting the pseudo sine wave signal a and the pseudo sine wave signal b by a coefficient respectively; Weighting means for multiplying each of the wave signals a, b and c1 by a weighting coefficient, and position information generating means for converting a change in the signal obtained as a result of the calculation by the weighting means into position information; Equipped encoder. 4. The weighting means according to claim 3, wherein the weighting coefficients for the pseudo sine wave signals a, b, and c1 are increasing functions of the absolute value of the pseudo sine wave signal having a large absolute value in a section having good linearity. Encoder. 5. A signal correcting means is provided immediately before and after the calculating means, and performs correction such as amplitude correction, DC correction and phase correction on at least one of the pseudo sine wave signals a, b and c1. The encoder according to claim 1. 6. The encoder according to claim 1, further comprising A / D conversion means for performing subsequent signal processing by a digital amount immediately after the original signal generation means.