JP4199583B2 - Inductive transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to inductive transducers, and more particularly to correcting differential errors caused by crosstalk signals.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an inductive transducer that detects relative displacement between a grid and a scale or an absolute position with respect to an origin based on electromagnetic induction between a grid and a scale opposed to each other at a predetermined interval is known.
[0003]
FIG. 6 shows the principle of detecting the absolute position between the grid 10 and the scale 12. The absolute position is the amount of displacement from a certain reference point (zero point). As shown in FIG. 6A, a plurality of transmission coils 10a, 10b, and 10c are provided in parallel on the grid 10, and a plurality of reception coils 10p, 10q, and 10r are provided corresponding to these transmission coils. It is done. Transmitting coils 10a and 10c are located at both ends of the central transmitting coil 10b, and receiving coils 10p and 10r are located at both ends of the central receiving coil 10q.
[0004]
On the other hand, the scale 12 is formed with a scale coil having a central portion having a pitch (period) of λ1 and an end portion having a pitch (period) of λ2. An assembly of coil portions having a period λ1 is referred to as λ1 scale coil track 14a, and an assembly of coil portions having a period λ2 is referred to as λ2 scale coil tracks 14b and 14c. The λ1 scale coil track 14a is opposed to the transmission coil 10b and the reception coil 10q located at the center, the λ2 scale coil track 14b is opposed to the transmission coil 10a and the reception coil 10p located at the ends, and the λ2 scale coil track 14c is the end. It faces the transmitting coil 10c and the receiving coil 10r located in the section. When the transmission coils 10a and 10c located at the end of the grid 10 are driven, an induced current is generated in the λ2 scale coil tracks 14b and 14c facing the transmission coils 10a and 10c, and this induced current is generated in the λ1 scale coil track 14a. Inflow magnetic flux is generated. Due to the magnetic flux from the λ1 scale coil track 14a, an induced voltage signal having a period λ1 is generated in the receiving coil 10q facing the λ1 scale coil track 14a. Further, when the transmission coil 10b located at the center of the grid 10 is driven, an induced current is generated in the λ1 scale coil track 14a facing the transmission coil 10b, and this induced current flows into the λ2 scale coil tracks 14b and 14c to generate a magnetic flux. Due to the magnetic flux from the λ2 scale coil tracks 14b, 14c, an induced voltage signal having a period λ2 is generated in the receiving coils 10p, 10r facing the λ2 scale coil tracks 14b, 14c. Since the periods of the two signals are different from λ1 and λ2, the relationship of the induced voltages between the two periods at a certain induced voltage value is not the same at all positions of the grid 10 with respect to the scale 12. That is, as shown in FIG. 6B, the induced voltage values of the period λ2 are not equal at the positions Xa and Xb where the voltage values V1a of the induced voltage of the period λ1 are the same. Therefore, the absolute position of the scale 12 (assuming that the scale 12 moves relative to the grid 10) can be detected by converting the position from the relationship between the induced voltages of two periods.
[0005]
Although the absolute position of the scale 12 is detected based on such a principle, when detecting an induced voltage signal with the period λ1, magnetic flux is generated in the λ2 scale coil tracks 14b and 14c at both ends opposite to the transmission coils 10a and 10c at both ends. This magnetic flux is mixed into the receiving coil 10q as a crosstalk signal. In other words, the receiving coil 10q should detect the λ1 induced voltage signal from the λ1 scale coil track 14a, but also detect the λ2 induced voltage signal due to the magnetic flux of the λ2 scale coil tracks 14b and 14c. It is. These crosstalk signals are included in the induced voltage signal of λ1, and an error (difference error) occurs at the detection position due to the crosstalk signal.
[0006]
In FIG. 7, the difference error as a function of the position of the scale 12 is shown. Since the scale coil track 14a of λ1 and the scale coil track of λ2 are in phase at the center of the scale 12, the difference error is 0. As the grid 10 moves away from the center of the scale 12, the difference from the λ1 scale coil track 14a becomes larger. Since the phases of the λ2 scale coil tracks 14b and 14c are shifted, the difference error also increases.
[0007]
Therefore, conventionally, in consideration of the difference error characteristic as shown in FIG. 7, the movable range of the scale 12 relative to the grid 10 is limited to the vicinity of the center of the scale 12, and the difference error increases linearly with respect to the position. The model is set to correct the difference error.
[0008]
[Patent Document 1]
JP 2001-255108 A
[0009]
[Problems to be solved by the invention]
However, when the relative movement range of the scale 12 and the grid 10 is limited to the vicinity of the center of the scale 12, there is a problem that the position measurement range is limited.
[0010]
Further, in order to eliminate the limitation of the measurement range, the grid 10 is moved over a wide range with respect to the scale 12, the difference error at each position is measured and stored in a memory or the like, and the memory is accessed each time the position is measured. Although it is conceivable to obtain a difference error correction value, there is a problem that the amount of data to be stored in the memory increases.
[0011]
Furthermore, in the two-wavelength inductive transducer using two periods λ1 and λ2 as shown in FIG. 6, the difference error can be corrected by a linear model near the center of the scale 12, but λ1 and λ2 In addition, there is a problem that a linear model cannot be used in a three-wavelength inductive transducer using λ3.
[0012]
FIG. 8 shows a scale 12 in a three-wavelength type inductive transducer. The configuration on the grid 10 side is the same as in FIG. The λ1 scale coil track 14a is positioned at the center, and the λ2 scale coil track 14b and the λ3 scale coil track 14c are positioned at both ends so as to sandwich the central scale coil track 14a. The λ1 scale coil track 14a faces the receiving coil 10q, the λ2 scale coil track 14b faces the receiving coil 10p, and the λ3 scale coil track 14c faces the receiving coil 10r. The transmission coils 10a and 10c are driven to generate a magnetic flux in the λ1 scale coil track 14a, and an induced voltage signal of λ1 due to this magnetic flux is detected by the receiving coil 10q. Further, the transmission coil 10b is driven to generate magnetic fluxes in the λ2 scale coil track 14b and the λ3 scale coil track 14c, and the induced voltage signals of λ2 and λ3 due to these magnetic fluxes are detected by the reception coils 10p and 10r, respectively. The position of the grid 10 is detected using the relationship between the induced voltage signals of λ1, λ2, and λ3. Even in this case, when the transmission coils 10a and 10c are driven, the crosstalk signal is mixed into the reception coil 10q by the magnetic fluxes of the scale coil track 14b of λ2 and the scale coil track 14c of λ3, and a difference error occurs.
[0013]
FIG. 9 shows the difference error as a function of the position of the scale 12. The difference error has a swell as shown in the figure, and the difference error is non-linear even in the vicinity of the center of the scale 12. Therefore, the difference error cannot be corrected by the linear model.
[0014]
An object of the present invention is to provide an inductive transducer capable of correcting a difference error without limiting the measurement range to a narrow range and without storing a large amount of correction data in a memory.
[0015]
[Means for Solving the Problems]
The present invention has a scale having at least first and second tracks, a first receiver arranged opposite to the first track, and a second receiver arranged corresponding to the second track, and arranged opposite to the scale. And the scale based on the grid, the first detection signal from the first receiver when driving the first track, and the second detection signal from the second receiver when driving the second track. And signal processing means for obtaining positional information between the grids, the signal processing means calculates a crosstalk signal by the second track included in the first detection signal based on the second detection signal, The crosstalk signal is removed from the first detection signal.
[0016]
In addition, the present invention includes a scale coil and a grid coil that are opposed to each other and are relatively movable, and the grid coil includes a transmission coil and a reception coil, and generates a magnetic flux from the transmission coil of the grid coil to generate the scale coil. An inductive transducer that generates an induced magnetic flux in a coil and receives the induced magnetic flux by the receiving coil of the grid coil to obtain positional information between the scale and the grid, and the scale coil has a central portion and an end of the scale. A plurality of coils having loops at the center are arranged along the longitudinal direction of the scale so as to have different periods at the center and at the end, and a first scale coil track at the center and a second scale coil at the end And the transmission coil of the grid coil drives the first scale coil track. A first transmission coil disposed opposite to the second scale coil track, and a second transmission coil disposed opposite to the first scale coil track to drive the second scale coil track, the grid The receiving coil of the coil includes a first receiving coil disposed to face the first scale coil track and a second receiving coil disposed to face the second scale coil track, and the first transmitting coil and the second receiving coil Control means for sequentially driving a transmission coil to process detection signals from the first reception coil and the second reception coil, wherein the first reception coil receives the first reception coil when the first transmission coil is driven. The crosstalk signal generated by the second scale coil track included in one detection signal is converted into the first value when the second transmission coil is driven. Calculated based on the second detection signal received by the receiving coils, and having a signal processing means for correcting the first detection signal with a crosstalk signal calculated.
[0017]
In addition, the present invention includes a scale coil and a grid coil that are opposed to each other and are relatively movable, and the grid coil includes a transmission coil and a reception coil, and generates a magnetic flux from the transmission coil of the grid coil to generate the scale coil. An induction type transducer that generates an induced magnetic flux in a coil and receives the induced magnetic flux by the receiving coil of the grid coil to obtain position information of a scale and a grid, and the scale coil includes a central portion and an end portion of the scale. A plurality of coils having a loop at the center are arranged along the measurement direction of the scale so that the period of the center part is λ1, the period of the upper end part is λ2, and the period of the lower end part is λ3. A scale coil track, a second scale coil track at the upper end, and a third scale coil track at the lower end, The transmission coil of the first coil includes a first transmission coil disposed opposite to the second scale coil track for driving the first scale coil track, and the third scale for driving the first scale coil track. A third transmission coil disposed opposite to the coil track; and a second transmission coil disposed opposite to the first scale coil track for driving the second scale coil track and the third scale coil track; The receiving coil of the grid coil is opposed to the first receiving coil disposed opposite to the second scale coil track, the second receiving coil disposed opposite to the first scale coil track, and the third scale coil track. Having a third receiver coil disposed;
Control means for sequentially processing the first transmission coil, the second transmission coil, and the third transmission coil to process detection signals from the first reception coil, the second reception coil, and the third reception coil; The second scale coil track and the third scale coil track included in the detection signal of the period λ1 received by the second receiver coil facing the first scale coil track when the one transmitter coil and the third transmitter coil are driven. Is calculated based on detection signals respectively received by the first receiving coil and the third receiving coil when the second transmitting coil is driven, and the calculated crosstalk signal is used to calculate the crosstalk signal of λ1. It has a signal processing means for correcting the detection signal.
[0018]
Here, it further includes storage means for storing an amplitude value when the crosstalk signal is a cosine wave signal, and the signal processing means calculates a phase of the cosine wave signal from the detection signal, and The crosstalk signal may be calculated using an amplitude value stored in the storage unit.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 shows a configuration block diagram of the inductive transducer according to the present embodiment. The configurations of the grid 10 and the scale 12 are the same as the three-wavelength configuration shown in FIG. That is, on the grid 10, a plurality of transmission coils 10a, 10b, and 10c are provided in parallel, and a plurality of reception coils 10p, 10q, and 10r are provided. Transmitting coils 10a and 10c are located at both ends of the central transmitting coil 10b, and receiving coils 10p and 10r are located at both ends of the central receiving coil 10q. The receiving coils 10p, 10q, and 10r are positioned in the width direction of the grid 10. Although only a single coil is shown in the figure as the receiving coil 10p, for example, a three-phase coil is arranged, and a coil shifted by 180 ° is arranged in order to improve the detection signal intensity by differential calculation. The same applies to the receiving coils 10q and 10r. If the three-phase coil is, for example, a center coil, a right coil, or a left coil, the position of the center coil is used as a reference for the position between the grid 10 and the scale 12.
[0021]
On the other hand, on the scale 12, the λ1 scale coil track 14a is positioned at the center, and the λ2 scale coil track 14b and the λ3 scale coil track 14c are positioned at both ends so as to sandwich the center λ1 scale coil track 14a. Since the scale coil tracks 14a, 14b, and 14c are configured by arranging a plurality of single scale coils that form a loop at the center and end of the scale 12 in the longitudinal direction or measurement direction of the scale 12, the λ1 scale coil track 14a and λ2 scale coil track 14b, λ1 scale coil track 14a and λ3 scale coil track 14c are electrically connected to each other. The transmission coil 10a faces the λ2 scale coil track 14b, the transmission coil 10b faces the λ1 scale coil track 14a, and the transmission coil 10c faces the λ3 scale coil track 14c. The λ1 scale coil track 14a faces the receiving coil 10q, the λ2 scale coil track 14b faces the receiving coil 10p, and the λ3 scale coil track 14c faces the receiving coil 10r. The opposing positional relationship is summarized as follows.
[0022]
Transmitting coil 10a-λ2 scale coil track 14b-receiving coil 10p
Transmitting coil 10b-λ1 scale coil track 14a-receiving coil 10q
Transmitting coil 10c-λ3 scale coil track 14c-receiving coil 10r
The transmission coils 10a, 10b, and 10c are the first, second, and third transmission coils, respectively, and the λ1, λ2, and λ3 scale coil tracks 14a, 14b, and 14c are the first, second, and third scale coil tracks, and the reception coil, respectively. When 10p, 10q, and 10r are referred to as the first, second, and third receiving coils, respectively, the facing relationship is as follows.
[0023]
First transmitter coil-second scale coil track-first receiver coil
Second transmitter coil-first scale coil track-second receiver coil
Third transmitter coil-third scale coil track-third receiver coil
The signal processing IC 16 includes an amplifier, an A / D converter, a processor, and a memory. The signal processing IC 16 supplies drive signals for sequentially driving the transmission coils 10a, 10b, and 10c, and detection signals from the reception coils 10p, 10q, and 10r. (Induced voltage signal) is input, and the position of the grid 10 is detected from detection signals of periods λ1, λ2, and λ3. That is, the signal processing IC 16 first drives the transmission coils 10a and 10c to generate a magnetic flux in the λ1 scale coil track 14a, and inputs a detection signal of the period λ1 generated in the reception coil 10q by this magnetic flux. Next, the transmitting coil 10b is driven to generate magnetic fluxes in the λ2 and λ3 scale coil tracks 14b and 14c, and the detection signals of the periods λ2 and λ3 generated in the receiving coils 10p and 10r by these magnetic fluxes are input. Two detection signals are processed to detect the absolute position of the scale 12 relative to the grid 10.
[0024]
Here, when driving the transmission coils 10a and 10c, the λ2 scale coil track 14b and the λ1 scale coil track 14a are configured by arranging a plurality of single-scale coils with loops at both ends and are electrically connected. Magnetic flux is generated not only in the coil track 14a but also in the λ2 scale coil track 14b and the λ3 scale coil track, and these magnetic fluxes are mixed into the receiving coil 10q as a crosstalk signal. Therefore, the signal processing IC 16 has three λ1, λ2, and λ3. When detecting the position by combining the two detection signals, the position of the scale 12 is detected by performing correction for removing the crosstalk signal included in the detection signal of λ1 from the receiving coil 10b. Details of the crosstalk signal removal will be described later.
[0025]
The operation unit 18 supplies user operations to the signal processing IC 16, and supplies, for example, a power ON / OFF signal and a reset signal to the signal processing IC 16.
[0026]
The display unit 20 displays the position information of the grid 10 detected by the signal processing IC 16.
[0027]
Although the grid 10 is shown as a single layer structure in the figure, it can be configured as a multilayer structure. When the grid 10 has a multilayer structure, for example, the first layer, the second layer, and the third layer are sequentially formed from the scale 12 side, and the transmission coils 10a, 10b, and 10c are formed in the first layer, and the second layer and the third layer are formed. The receiving coils 10p, 10q, and 10r are formed in the layer. In the multilayer grid 10, the signal processing IC 16 may be formed on the surface opposite to the scale 12 via a magnetic shield layer. The multilayer structure is formed by a so-called buildup method in which layers are sequentially stacked on both sides of the core layer. Transmitting coils 10a, 10b and 10c and receiving coils 10p, 10q and 10r are formed on one side of the core layer, and a wiring layer and a signal processing IC 16 are formed on the other side.
[0028]
Hereinafter, the crosstalk signal removal processing (difference error correction processing) executed by the signal processing IC 16 will be described. Note that the absolute position detection using the detection signals of λ1, λ2, and λ3 after removing the crosstalk signal is the same as in the prior art, and is therefore omitted.
[0029]
FIG. 2 shows a plan view of the scale 12. As described above, when the transmission coil 10a is driven, a magnetic flux is generated in the λ2 scale coil track 14b facing the transmission coil 10a, and a crosstalk signal is generated by this magnetic flux. Since the drive current flowing through the transmission coil 10a is constant, the magnetic flux density generated in each coil of the λ2 scale coil track 14b is also constant. Therefore, the crosstalk signal detected by the receiving coil 10q periodically changes according to the phase φ2 of the λ2 scale coil track 14b with respect to the λ1 scale coil track 14a. The phase φ2 is a phase shift of the λ2 scale coil track 14b detected with the origin as a reference. FIG. 3 shows a change in the intensity of the crosstalk signal caused by the λ2 scale coil track 14b. In the figure, the horizontal axis is the position of the scale 12. When the driving direction of the transmission coil 10a is +, the crosstalk signal is offset in the + direction (that is, in the same direction as the induced current generated in the λ1 scale coil 14a) and appears as a cosine wave having a period of λ2.
[0030]
On the other hand, when the transmission coil 10c is driven, a magnetic flux is generated in the λ3 scale coil track 14c facing the transmission coil 10c, and a crosstalk signal is generated by this magnetic flux. The drive current flowing through the transmission coil 10c is also constant, but has a polarity opposite to that of the current flowing through the transmission coil 10a. This is because noise and offset are canceled by the differential between adjacent scale coils and the detection signal intensity of λ1 is increased. Since the drive currents of the transmission coils 10a and 10c have opposite polarities, induced currents in the opposite directions of + and-are alternately generated in the λ1 scale coil track 14a as shown in the figure, and the reception coil 10q receives these signals. Output as a differential signal. The crosstalk signal generated by the λ3 scale coil track 14c is opposite in polarity to the crosstalk signal generated by the λ2 scale coil track 14b, and its intensity periodically changes according to the phase φ3 of the λ3 scale coil track 14c with respect to the λ1 scale coil track 14a. To do. FIG. 4 shows the intensity change of the crosstalk signal due to the λ3 scale coil track 14c. The crosstalk signal appears as a cosine wave having a period of λ3 that is offset in the negative direction and in the negative direction.
[0031]
FIG. 5 shows a sum signal of two crosstalk signals having periods λ2 and λ3. Since the crosstalk signal of λ2 and the crosstalk signal of λ3 have opposite polarities and the same intensity, the offset of the sum signal is canceled and only the periodic signals of the periods λ2 and λ3 are obtained.
[0032]
Now, assuming that the crosstalk signal from the λ2 scale coil track 14b is C2 = αcos (φ2) and the crosstalk signal from the λ3 scale coil track 14c is C3 = αcos (φ3), the crosstalk signal is detected from the detection signal of the receiving coil 10q. The corrected signal S obtained by removing
[Expression 1]
S = So- (C2 + C3)
= So-αcos (φ2) -αcos (φ3) (1)
It is. Here, So is the detection signal of the reception coil 10q (detection signal before correction), and α is the amplitude of the crosstalk signal. By detecting the phases φ2 and φ3 and the amplitude α, the signal processing IC 16 can obtain the corrected signal S using the equation (1). Hereinafter, these detection methods will be described.
[0033]
<Detection of phase φ2>
After the transmitting coils 10a and 10c are driven, the transmitting coil 10b is driven to generate a magnetic flux in the λ2 scale coil track 14b, and this magnetic flux is detected by the receiving coil 10p to output a detection signal (induced voltage signal) of λ2. . The detection signal of λ2 represents the relative position of the receiving coil 10p with respect to the λ2 scale coil track 14b, that is, the relative position of the receiving coil 10q with respect to the λ2 scale coil track 14b. Therefore, the position where the detection signal of λ2 from the receiving coil 10p becomes the maximum value (the phase shift between the λ1 scale coil track 14a and the λ2 scale coil track 14b is 0) is the origin position of the phase φ2, and the detection signal of λ2 The phase φ2 is detected by detecting the intensity of.
[0034]
<Detection of phase φ3>
The detection principle is the same as that of the phase φ2, and after driving the transmission coils 10a and 10c, the transmission coil 10b is driven to generate a magnetic flux in the λ3 scale coil track 14c, and this magnetic flux is detected by the reception coil 10r to detect λ3 A detection signal (induced voltage signal) is output. The detection signal of λ3 represents the relative position of the receiving coil 10r with respect to the λ3 scale coil track 14c, that is, the relative position of the receiving coil 10q with respect to the λ3 scale coil track 14c. Therefore, the position where the detection signal of λ3 from the receiving coil 10r becomes the maximum value (the phase shift between the λ1 scale coil track 14a and the λ3 scale coil track 14c is 0) is the origin position of the phase φ3, and the detection signal of λ3 The phase φ3 is detected by detecting the intensity of.
[0035]
<Detection of amplitude α>
The amplitude α is the drive current value of the transmission coils 10a and 10c, the distance between the λ1 scale coil track 14a and the λ2 scale coil track 14b, the distance between the λ1 scale coil track 14a and the λ3 scale coil track 14c, the grid 10 and the scale 12. Fluctuates due to gaps. Therefore, although it may be a fixed value calculated from the design value, the scale 12 is actually moved by several cycles, the transmission coils 10a and 10c are driven, the signal So from the reception coil 10b is Fourier-analyzed, and λ2 and λ3 It is preferable to detect the amplitude of the signal component. The detected amplitude α is stored in a memory in the signal processing IC 16.
[0036]
As described above, in this embodiment, the transmission coils 10a and 10c are driven to detect the induced voltage signal of λ1 by the reception coil 10q, and then the transmission coil 10b is driven and the reception coils 10p and 10r have λ2 and λ3. When the induced voltage signal is detected and the induced voltage signals of λ1, λ2, and λ3 are combined to detect the position of the scale 12, the phase φ2 is detected from the induced voltage signal of λ2, and the phase is detected from the induced voltage signal of λ3. φ3 is detected, and the crosstalk signal (difference error) included in the induced voltage signal of λ1 is corrected using the amplitude α previously detected and stored in the memory with these phases φ2 and φ3. The position of the data can be detected with a small amount of data and with high accuracy. In this embodiment, since the linear model is not used, the measurement range is not limited only to the vicinity of the center of the scale 12.
[0037]
In the present embodiment, the three-wavelength type inductive transducer is exemplified, but the present invention can be similarly applied to a two-wavelength type inductive transducer as shown in FIG. In this case, if the crosstalk signal by the scale coil tracks 14b and 14c of λ2 is C2, the corrected signal S obtained by removing the crosstalk signal from the detection signal of the receiving coil 10q is:
[Expression 2]
S = So- (C2 + C2)
= So-2αcos (φ2) (2)
It is. After the transmitting coils 10a and 10c are driven, the transmitting coil 10b is driven to generate a magnetic flux in the λ2 scale coil tracks 14b and 14c, and this magnetic flux is detected by the receiving coil 10p to detect the λ2 detection signal (induced voltage signal). Is output. The detection signal of λ2 represents the relative position of the reception coils 10p and 10r with respect to the scale coil tracks 14b and 14c of λ2, that is, the relative position of the reception coil 10q with respect to the scale coil tracks 14b and 14c of λ2. Therefore, the position where the detection signal of λ2 from the receiving coil 10p becomes the maximum value (at this time, the phase shift between the scale coil track 14a of λ1 and the scale coil tracks 14b and 14c of λ2 is 0) is the origin position of the phase φ2, The phase φ2 is detected by detecting the intensity of the detection signal of λ2.
[0038]
As for the amplitude α, the scale 12 is actually moved by several cycles, the transmitting coils 10a and 10c are driven, the signal So from the receiving coil 10q is Fourier-analyzed, and the amplitude of the signal component of λ2 is detected. What is necessary is just to memorize | store in the memory in processing IC16. Since the difference error due to the crosstalk signal can be corrected without using a linear model, it is not necessary to limit the measurement range to the vicinity of the center of the scale 12.
[0039]
The inductive transducer according to this embodiment can be incorporated into, for example, an electronic caliper.
[0040]
【The invention's effect】
As described above, according to the present invention, the position can be detected with high accuracy without increasing the amount of data stored in the memory and without limiting the measurement range.
[Brief description of the drawings]
FIG. 1 is a configuration block diagram of an inductive transducer according to an embodiment.
FIG. 2 is a plan view of a scale.
FIG. 3 is an explanatory diagram of a crosstalk signal by a scale coil track of λ2.
FIG. 4 is an explanatory diagram of a crosstalk signal by a scale coil track of λ3.
FIG. 5 is an explanatory diagram of a sum signal of two crosstalk signals.
FIG. 6 is a configuration diagram of a grid and a scale of a two-wavelength type inductive transducer.
FIG. 7 is an explanatory diagram of a difference error due to a crosstalk signal.
FIG. 8 is a configuration diagram of a grid and a scale of a three-wavelength type inductive transducer.
FIG. 9 is an explanatory diagram of a difference error due to a crosstalk signal.
[Explanation of symbols]
10 grids, 12 scales, 16 signal processing ICs, 18 operation units, 20 display units.

Claims (4)

A scale having at least first and second tracks;
A grid disposed opposite the scale having a first receiver disposed opposite the first track and a second receiver disposed corresponding to the second track;
Based on the first detection signal from the first receiver when the first track is driven and the second detection signal from the second receiver when the second track is driven, between the scale and the grid Signal processing means for obtaining position information;
Have
The signal processing means calculates a crosstalk signal by the second track included in the first detection signal based on the second detection signal, and removes the crosstalk signal from the first detection signal. Inductive transducer. A scale coil and a grid coil that are arranged opposite to each other and are movable relative to each other are provided. The grid coil includes a transmission coil and a reception coil, and generates a magnetic flux from the transmission coil of the grid coil to generate an induction magnetic flux in the scale coil. An inductive transducer that receives the induced magnetic flux by the receiving coil of the grid coil and obtains position information between the scale and the grid,
The scale coil is a first central portion formed by arranging a plurality of coils having loops at the central portion and the end portion of the scale so as to have different periods along the longitudinal direction of the scale. A scale coil track and an end second scale coil track;
The transmission coil of the grid coil includes a first transmission coil disposed opposite to the second scale coil track to drive the first scale coil track, and the first scale coil to drive the second scale coil track. A second transmission coil disposed opposite to the scale coil track, wherein the reception coil of the grid coil is disposed opposite to the first reception coil and the second scale coil track disposed opposite to the first scale coil track; A second receiving coil,
Control means for sequentially processing the first transmission coil and the second transmission coil to process detection signals from the first reception coil and the second reception coil, wherein the first transmission coil is driven when the first transmission coil is driven. A crosstalk signal from the second scale coil track included in a first detection signal received by one reception coil is converted into a second detection signal received by the second reception coil when the second transmission coil is driven. An inductive transducer comprising: a signal processing unit that calculates based on the calculated crosstalk signal and corrects the first detection signal using the calculated crosstalk signal. A scale coil and a grid coil that are arranged opposite to each other and are movable relative to each other are provided. The grid coil includes a transmission coil and a reception coil, and generates a magnetic flux from the transmission coil of the grid coil to generate an induction magnetic flux in the scale coil. Inductive transducer for obtaining the position information of the scale and grid by receiving the induced magnetic flux by the receiving coil of the grid coil,
In the scale coil, a coil having a loop at the center and end of the scale is arranged such that the period of the center is λ1, the period of the upper end is λ2, and the period of the lower end is λ3 along the measurement direction of the scale. A first scale coil track at the center, a second scale coil track at the upper end, and a third scale coil track at the lower end.
The transmission coil of the grid coil includes a first transmission coil disposed opposite to the second scale coil track for driving the first scale coil track, and the first coil for driving the first scale coil track. A third transmission coil disposed opposite to the three scale coil track; and a second transmission coil disposed opposite to the first scale coil track for driving the second scale coil track and the third scale coil track. The receiving coil of the grid coil includes a first receiving coil disposed to face the second scale coil track, a second receiving coil disposed to face the first scale coil track, and the third scale coil track. A third receiving coil disposed opposite to
Control means for sequentially processing the first transmission coil, the second transmission coil, and the third transmission coil to process detection signals from the first reception coil, the second reception coil, and the third reception coil; The second scale coil track and the third scale coil track included in the detection signal of the period λ1 received by the second receiver coil facing the first scale coil track when the one transmitter coil and the third transmitter coil are driven. Is calculated based on detection signals respectively received by the first receiving coil and the third receiving coil when the second transmitting coil is driven, and the calculated crosstalk signal is used to calculate the crosstalk signal of λ1. An inductive transducer comprising signal processing means for correcting a detection signal. The inductive transducer according to claim 3, further comprising:
Storage means for storing an amplitude value when the crosstalk signal is a cosine wave signal, the signal processing means calculates a phase of the cosine wave signal from the detection signal, and the phase and the storage means An inductive transducer characterized in that the crosstalk signal is calculated using a stored amplitude value.

Images