JP2005077150A - Induction type position detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction type position detector capable of measuring a position by an element other than a waveform of a signal received by a reception coil. <P>SOLUTION: A moving direction (measuring axis x) of a sensor head 5 is inclined with respect to an extension direction of tracks Ta, Tb formed in parallel to a scale 3. Intensity of the signal received by the reception coil 19 is thereby varied along with the moving of the sensor head 5. The signal intensity is correlated with the position of the sensor head 5 to measure the position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is applied to a small measuring tool typified by a caliper or a micrometer, a linear scale, a drive device such as a CD or MD, and a sensor device. Relates to the device.

  Conventionally, an inductive position detector (hereinafter sometimes referred to as an “encoder”) has been used for precise measurement of linear displacement, angular displacement, and the like. The encoder includes a scale in which magnetic flux coupling windings are arranged at a predetermined pitch, and a sensor in which a transmission winding and a reception winding that are electromagnetically coupled to the magnetic flux coupling windings are arranged so as to be relatively movable with respect to the scales. And a head.

There are an incremental type (for example, Patent Document 1) and an absolute type (for example, Patent Document 2). In the incremental type, the position of the sensor head (that is, the amount of displacement of the sensor head from the origin) is obtained by counting signals received by the receiving winding with respect to the origin. On the other hand, the absolute type obtains the absolute position of the sensor head with reference to the origin by expressing the amount of displacement from the origin by a binary signal. The absolute type has a more complicated structure than the incremental type, but it is not necessary to move the sensor head from the origin to the measurement position because the measurement position can be specified by the signal received at the measurement position.
Japanese Patent Laid-Open No. 10-318781 (FIGS. 1 and 2) JP 2001-108484 A (FIG. 2)

  The encoder generally calculates the position of the sensor head using the correlation between the waveform of the signal (sinusoidal displacement signal) received by the receiving winding and the position of the sensor head. If there is an element other than the waveform to calculate the position, the performance of the encoder can be improved.

  An object of the present invention is to provide an inductive position detecting device capable of measuring a position with an element other than a waveform of a signal received by a receiving winding.

  The inductive position detection apparatus according to the present invention includes a scale on which a track having a structure in which a plurality of magnetic flux coupling windings are arranged, and a transmission winding and a reception winding that can be electromagnetically coupled to the track. And a sensor head disposed opposite to the scale so as to be relatively movable in an oblique direction with respect to the direction in which the track extends.

According to the inductive position detection device of the present invention, the relative movement direction of the sensor head is inclined with respect to the track extending direction. Therefore, the relative movement of the sensor head changes the force of electromagnetic coupling between at least one of the transmission winding and the reception winding and the track, and the intensity of the signal received by the reception winding changes accordingly. Therefore, since the signal intensity and the position of the sensor head have a correlation, the signal intensity can be used for position measurement. For example, the following effects occur.
(A) When the track is an incremental pattern, measurement similar to the absolute type can be performed. (B) When the track is an absolute pattern, the measurement range can be expanded. (C) By measuring the change in signal intensity with a direction (lateral direction) orthogonal to the longitudinal direction of the scale, measurement in the orthogonal direction is possible.

  In the inductive position detecting device according to the present invention, the track may be an incremental pattern composed of a plurality of magnetic flux coupling windings having the same shape. According to this, although the track is an incremental pattern, it is not necessary to move the sensor head from the origin to the measurement position when measuring the position. Therefore, measurement similar to the absolute type can be performed.

  In the inductive position detecting device according to the present invention, the track may have a structure in which an absolute pattern composed of a plurality of magnetic flux coupling windings having different shapes is repeatedly arranged in series.

  As described above, according to the present invention, the signal strength of the reception winding changes according to the relative movement of the sensor head. For this reason, the position of the sensor head can be specified even if the same binary signal is generated at a different position of the scale. Therefore, when the track is an absolute type pattern, the track can have a structure in which the absolute type pattern is repeatedly arranged in series, so that the measurement range can be widened.

  In the inductive position detection device according to the present invention, a plurality of tracks can be formed in parallel with the scale so that the position where the signal intensity of the reception winding reaches a peak is different for each track.

  According to this, the position where the intensity of the signal received by the receiving winding reaches a peak differs for each track. Therefore, the combination of the received signal strengths corresponding to each track (for example, when there are two tracks, the ratio of the signal strength received from one track to the signal strength received from the other track) The position can be specified by making it correspond to the relative position of the head. Therefore, the position can be specified even if there are a plurality of positions having the same signal intensity in each track. Further, even if the gap between the scale and the sensor head is different, the position specification is not affected.

  In the inductive position detecting device according to the present invention, the direction in which the track extends can be oblique to the longitudinal direction of the scale. According to this, the relative movement direction of the sensor head can be made to coincide with the longitudinal direction of the scale while being inclined with respect to the track extending direction. Therefore, it is possible to prevent a change in the design of a device incorporating the inductive position detection device due to a mismatch between the relative movement direction and the longitudinal direction of the scale.

  As described above, according to the present invention, the strength of the signal received by the receiving winding can be used for the position measurement, so that the performance of the inductive position detecting device can be improved.

  Hereinafter, first to third embodiments of an inductive position detection device according to the present invention will be described with reference to the drawings. In the drawings describing the second and third embodiments, the same components as those shown in the already described embodiments are designated by the same reference numerals and the description thereof is omitted.

  In the first embodiment, the position of the sensor head in the measurement axis direction is detected using the intensity ratio of the signals received by each receiving winding from two tracks that are incremental patterns. As a result, the same measurement as the absolute type can be performed while the track is an incremental pattern. First, the configuration of the inductive position detection device 1 according to the first embodiment will be described. FIG. 1 is a plan view showing a schematic configuration of the apparatus 1.

  The inductive position detection device 1 is composed of a scale 3 and a sensor head (also referred to as a grid) 5 disposed opposite to the scale 3. A part of the scale 3 in the longitudinal direction appears. The scale 3 is tilted in the yaw direction D. That is, the longitudinal direction of the scale 3 is inclined with respect to the measurement axis x. The sensor head 5 is arranged to be movable along the measurement axis x with a predetermined gap with respect to the scale 3. Note that the sensor head may be fixed and the scale may move. That is, it is only necessary that the sensor head and the scale are disposed so as to be relatively movable with respect to each other.

  The scale 3 includes an insulating substrate 7 such as glass or silicon, and a plurality of magnetic flux couplings having the same shape along the longitudinal direction of the scale 3 with a scale pitch λ are provided on the surface of the substrate 7 facing the sensor head 5. Windings 9 are arranged. The magnetic flux coupling winding 9 is constituted by a rectangular first coupling loop 11 and a rectangular second coupling loop 13 connected thereto. Tracks Ta and Tb are formed in parallel in the longitudinal direction of the scale 3. The track Ta is constituted by a plurality of first coupling loops 11 arranged in the longitudinal direction of the scale 3, while the track Tb is constituted by a plurality of second coupling loops 13 arranged in the longitudinal direction of the scale 3. Tracks Ta and Tb are incremental patterns. The measurement axis x which is the moving direction of the sensor head 5 is inclined with respect to the direction in which the tracks Ta and Tb extend.

  The sensor head 5 has an insulating substrate 15 such as glass or silicon. Two transmission windings 17 (17a, 17b) are formed in parallel along the measurement axis x on the surface of the insulating substrate 15 facing the scale 3. The shape of the transmission winding 17 is a rectangular shape whose longitudinal direction is along the measurement axis x. The transmission winding 17a can be electromagnetically coupled to the track Ta, and the transmission winding 17b can be electromagnetically coupled to the track Tb.

  Reception windings 19 (19 a, 19 b) are arranged on the surface side of the insulating substrate 15 facing the scale 3 and inside each transmission winding 17. Both of the windings 19 are configured such that two coil portions 21 and 23 having a structure wound a plurality of times are arranged so as to be insulated and overlap each other. The coil portions 21 and 23 are arranged with a phase shifted from each other by a quarter of the scale pitch λ.

  The receiving winding 19a can be electromagnetically coupled to the track Ta, and the receiving winding 19b can be electromagnetically coupled to the track Tb. The sensor head 5 is aligned with the scale 3 so that the position where the intensity of the signal received by the reception winding 19a peaks and the position of the reception winding 19b are different, that is, an offset is generated ( This will be further described in the operation of the device 1). Note that the receiving winding may be of a type having one coil part, a so-called three-phase type in which three coil parts are shifted in phase by 1/3, or a multiphase type having more than that.

  The terminals of the transmission winding 17 and the reception winding 19 are connected to an IC circuit (not shown) that performs calculation and control for measuring displacement through wiring. The transmission winding 17, the reception winding 19, and the magnetic flux coupling winding 9 are made of a material having a low electrical resistance such as aluminum, copper, or gold.

  Next, the operation of the guidance type position detection apparatus 1 will be described. FIG. 2 is a graph showing the intensity of signals received by the reception windings 19a and 19b of the apparatus 1. The case where the gap between the scale 3 and the sensor head 5 is G1 and the case where G2 is larger than G1 are shown. The signal intensity peaks of the windings 19a and 19b are when the position of the sensor head 5 is xa and xb, respectively. Between the position xa and the position xb, there is a position xc where the signal strengths of the winding 19a and the winding 19b coincide. The position xc is the center of the scale 3.

  FIG. 3 is a plan view showing the position of the sensor head where the signal intensity reaches a peak, and corresponds to FIG. FIG. 4 is a plan view showing a positional relationship between a track and a transmission winding / reception winding at a position where the reception signal reaches a peak. At the position xa, the electromagnetic coupling force between the transmission winding 17a and the track Ta (magnetic flux coupling winding) is maximized, so that the intensity of the signal received by the reception winding 19a becomes a peak. On the other hand, at the position xb, the electromagnetic coupling force between the transmission winding 17b and the track Tb is maximized, so that the intensity of the signal received by the reception winding 19b reaches a peak. If the receiving winding is arranged so that the electromagnetic coupling force between the receiving winding and the track changes, the signal intensity reaches a peak at a position where the electromagnetic coupling force between the receiving winding and the track becomes maximum.

  According to the guidance type position detection apparatus 1, the moving direction of the sensor head 5 is inclined with respect to the direction in which the tracks Ta and Tb extend. Therefore, due to the movement of the sensor head 5, the electromagnetic coupling force between the transmission winding 17a and the track Ta and the electromagnetic coupling force between the transmission winding 17b and the track Tb change, and accordingly, the reception windings 19a and 19b receive them. The signal strength changes. Therefore, since the signal intensity and the position of the sensor head 5 have a correlation, the signal intensity can be used for position measurement.

  However, in the first embodiment, as shown in FIG. 2, if only one of the reception windings 19a and 19b is used, two positions having the same signal intensity are generated. The position of 5 cannot be specified. Therefore, the peak of the signal intensity of the reception windings 19a and 19b is shifted (in other words, the position where the intensity of the signal received by the reception winding reaches the peak differs for each track), and the intensity ratio of these signals and the sensor head The position is specified in correspondence with the position of. Thereby, although the track is an incremental pattern, the same measurement as the absolute type can be performed. That is, it is not necessary to move the sensor head 5 from the origin to the measurement position during measurement.

  Now, if the signal intensity is used for specifying the position, the influence caused by the difference in the gap between the scale 3 and the sensor head 5 can be reduced. This will be described below. FIG. 5 is a graph showing the signal strength ratio of the reception windings 19a and 19b. In either case of the gaps G1 and G2, the signal intensity ratio shows the same tendency and gradually increases. Therefore, when the inductive position detection device 1 is assembled, an alignment error occurs between the sensor head 5 and the scale 3, so that the measurement position can be specified even if the gap changes. The signal intensity ratio is shown by a straight line, but this is only used for convenience to show the same tendency as described above.

  Next, an inductive position detection apparatus according to the second embodiment will be described focusing on differences from the first embodiment. FIG. 6 is a plan view showing a schematic configuration of the apparatus 31 and corresponds to FIG.

  The second embodiment is different from the first embodiment in that the extending direction of the tracks Ta and Tb is inclined with respect to the longitudinal direction of the scale 3. As a result, the moving direction of the sensor head 5 (measurement axis x) can be made to coincide with the longitudinal direction of the scale 3 while the moving direction (measurement axis x) of the sensor head 5 is inclined with respect to the direction in which the tracks Ta and Tb extend. Therefore, according to the second embodiment, it is possible to prevent a change in the design of a device incorporating the inductive position detection device 31 due to a mismatch between the moving direction of the sensor head 5 and the longitudinal direction of the scale 3.

  Next, a third embodiment will be described. FIG. 7 is a plan view showing a schematic configuration of the inductive position detecting device 41 according to the third embodiment. The third embodiment is different from the previous embodiments in that the tracks Ta and Tb of the scale 3 have an absolute pattern.

  On the scale 3, absolute patterns 43 and 45 are arranged in series. The plurality of magnetic flux coupling windings 9 constituting the pattern of the absolute pattern 43 have different shapes, and one cycle is constituted by the plurality of magnetic flux coupling windings 9. The pattern 45 is the same pattern as the pattern 43. For this reason, the same cycle is repeated in the pattern 43 and the pattern 45. The configuration of the sensor head 5 is the same as that of the first and second embodiments.

  In the case of only the absolute pattern 43, the binary generated based on the reception winding (corresponding to the reception windings 19a and 19b in FIG. 1) of the sensor head 5 of the device 41, as in the case of a normal absolute type encoder. The position of the sensor head 5 can be specified by the signal. The same applies to the case of only the absolute pattern 45. However, when the patterns 43 and 45 are arranged in series, it is impossible to determine on which pattern the sensor head 5 is located only by the binary signal. Therefore, the third embodiment uses a signal strength ratio in addition to the binary signal. Details will be described below.

  FIG. 8 is a graph showing the intensity of a signal received by the reception winding (corresponding to the reception windings 19a and 19b in FIG. 1) of the sensor head 5 of the device 41. As in the previous embodiments, the signal intensity peaks are shifted between the reception winding 19a and the reception winding 19b. When the signal strength ratio (the signal strength of the receiving winding 19b / the signal strength of the receiving winding 19a) is smaller than 1, the binary signal can be specified as a pattern 43, and when it is larger, it can be specified as a pattern 45.

  As described above, according to the third embodiment, since the tracks Ta and Tb have a structure in which absolute patterns are repeatedly arranged in series, the measurement range can be expanded. For example, if the length of one absolute pattern is 150 mm, it is possible to measure up to 300 mm.

  In the third embodiment, there are two absolute patterns, but three or more may be used. The scale of the second embodiment can also be applied to the scale of the third embodiment.

  In the first to third embodiments, for example, as shown in FIG. 1, when the sensor head 5 is moved along the measurement axis x, the y direction (of the scale 3 is perpendicular to the longitudinal direction of the scale 3). The position of the sensor head 5 in the lateral direction is also displaced. FIG. 9 is a graph showing the relationship between the displacement in the lateral direction and the signal intensity. It can be seen that the graph of FIG. 9 shows the same tendency as the graph of FIG. Therefore, the lateral direction measurement can be performed by associating the lateral displacement amount with the signal intensity. Since the position in the lateral direction has a correlation with the position on the measurement axis x of the sensor head 5, the absolute position on the measurement axis x of the sensor head 5 may be specified based on the position in the lateral direction.

  In the first to third embodiments, the case where there are two tracks has been described, but three or more tracks may be used. One track may be used. When there is one track, one end of the scale 3 may be a peak of signal intensity, and the signal intensity may be reduced toward the other end.

  Finally, a caliper 51 equipped with the inductive position detection device according to this embodiment will be described. 10 is an exploded perspective view of the caliper 51, and FIG. 11 is a plan view showing the main scale 53 and the scale 3 provided in the caliper. The caliper 51 is mounted with the second embodiment shown in FIG. 6, but the first and third embodiments may be used.

  As shown in FIGS. 10 and 11, the caliper 51 includes a main scale 53. The scale 3 is attached to the main scale 53. The caliper 51 includes a slider assembly 55 that is disposed on the main scale 53 and that moves along the measurement axis x of the main scale 53.

  The slider assembly 55 includes a base 57. The slider assembly 55 also has the sensor head 5 attached to the base 57 on the main scale 53. Accordingly, the base 57 and the sensor head 5 move as a unit along the main scale 53. The measured distance is displayed on the digital display 59, which is attached to the cover 61 of the slider assembly 55.

It is a top view which shows schematic structure of the induction | guidance | derivation type position detection apparatus which concerns on 1st Embodiment. It is a graph which shows the intensity | strength of the signal received with the receiving winding of the induction | guidance | derivation type position detection apparatus shown in FIG. In 1st Embodiment, it is a top view which shows the position of the sensor head from which signal strength becomes a peak. In 1st Embodiment, it is a top view which shows the positional relationship of the track | truck and the transmission winding and the reception winding in the position where a signal strength becomes a peak. 4 is a graph illustrating a signal intensity ratio between two reception windings in the first embodiment. It is a top view which shows schematic structure of the induction | guidance | derivation type position detection apparatus which concerns on 2nd Embodiment. It is a top view which shows schematic structure of the induction | guidance | derivation type position detection apparatus which concerns on 3rd Embodiment. In 3rd Embodiment, it is a graph which shows the intensity | strength of the signal received with the receiving winding. In 1st-3rd embodiment, it is a graph which shows the relationship between the displacement amount of a lateral direction, and signal strength. It is a disassembled perspective view of a caliper carrying the induction | guidance | derivation type position detection apparatus which concerns on 2nd Embodiment. It is a top view of the caliper main scale and scale shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inductive position detection apparatus, 3 ... Scale, 5 ... Sensor head, 7 ... Insulating substrate, 9 ... Magnetic flux coupling winding, 11 ... 1st coupling loop, 13. ..Second coupling loop, 15 ... insulating substrate, 17, 17a, 17b ... transmitting winding, 19, 19a, 19b ... receiving winding, 21,23 ... coil portion, 31,41 ... Inductive position detector, 43, 45 ... Absolute pattern, 51 ... Vernier caliper, 53 ... Main scale, 55 ... Slider assembly, 57 ... Base, 59 ... Digital Display device, 61 ... cover, Ta, Tb ... track, D ... yaw direction

Claims (5)

A scale on which a track having a structure in which a plurality of magnetic flux coupling windings are arranged;
A sensor head that is formed to be capable of electromagnetically coupling with the track and is disposed opposite to the scale so as to be movable in an oblique direction with respect to the direction in which the track extends;
An inductive position detecting device comprising: The track is an incremental pattern composed of the plurality of magnetic flux coupling windings having the same shape.
The inductive position detecting device according to claim 1. The track has a structure in which an absolute pattern composed of the plurality of magnetic flux coupling windings having different shapes is repeatedly arranged in series on the scale.
The inductive position detecting device according to claim 1. A plurality of the tracks are formed in parallel with the scale so that the position where the signal strength of the reception winding reaches a peak is different for each track.
The inductive position detecting device according to any one of claims 1 to 3. The direction in which the track extends is oblique to the longitudinal direction of the scale.
The inductive position detecting device according to any one of claims 1 to 4, wherein:

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