JP4913495B2 - Inductive displacement detector - Google Patents

Description

  The present invention relates to an inductive displacement detection apparatus using an induced current that detects a movement amount or a position between two members using a current signal induced by a magnetic field.

The inductive displacement detection device is suitable for precise measurement such as linear displacement and angular displacement, and is applied to, for example, calipers, micrometers, indicators, linear scales and the like. 2. Description of the Related Art Conventionally, an inductive displacement detecting device has a scale in which plates or magnetic flux coupling windings serving as magnetic flux coupling members are arranged at a predetermined pitch, and is disposed so as to be capable of relative movement with respect to the scale, and a plate or magnetic flux coupling winding. And a sensor head in which a transmission winding and a reception winding capable of magnetic flux coupling are arranged (for example, Patent Document 1).
JP-A-8-313295 (FIG. 4)

  In order to improve the resolution and increase the accuracy of the inductive displacement detection device, it is only necessary to reduce the pitch of the plate serving as the magnetic flux coupling member, the pitch of the magnetic flux coupling winding, or the dimensions of the receiving loop constituting the receiving winding. Since the plate and the magnetic flux coupling winding have a simple shape, it is easy to narrow their pitch. On the other hand, the receiving winding is a relatively complicated shape that connects multiple receiving loops in the relative movement direction of the sensor head when the output signal from the receiving winding is interpolated to improve resolution. It becomes. That is, the sensor head is configured by stacking a plurality of insulating plates arranged with the receiving windings shifted in phase. In particular, the problem here is the formation position of the contact portion for connecting the receiving loops arranged on each of the plurality of insulating substrates.

  In order to improve the resolution in this way, the receiving winding has a problem with its design rule such as the formation position of the contact portion. On the other hand, if a thin film multilayer substrate or a high-density build-up substrate is used as the substrate for forming the reception winding, the critical dimension of the reception loop can be designed to be smaller. However, if such a substrate is used, the manufacturing cost of the inductive displacement detector increases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an inductive displacement detection device with high resolution and high accuracy at low cost.

  The inductive displacement detection apparatus according to the present invention is a scale in which a plurality of magnetic flux coupling members are disposed along the measurement axis, and is opposed to the scale and is relatively movable in the measurement axis direction with respect to the scale. A transmission winding for supplying magnetic flux to the plurality of magnetic flux coupling members, and a multi-phase reception winding comprising a reception loop that forms a pair loop along the measurement axis that can be magnetically coupled to the magnetic flux coupling members are formed. The pitch of the magnetic flux coupling member in the measurement axis direction is λ / N (where N is an odd number of 3 or more, the same applies hereinafter), where λ is the pitch in the measurement axis direction of the pair loop. In the inductive displacement detection device set to, the reception loop is formed by a first wiring formed in a first layer and a second wiring formed in a second layer, and is arranged in the measurement axis direction. A pair of center positions The first wiring and the second wiring are connected to each other through the contact portion so that the wirings of the same layer do not intersect with each other, and the first and second wirings are connected to the contacts. A first parallel portion, a first inclined portion, and a second parallel portion that are sequentially symmetrically arranged on both sides of the measurement axis direction of the portion, from the second parallel portion to the second parallel portion of the adjacent receiving loop A distance between the centers of the first inclined portions on both sides of the contact portion in the measurement axis direction is set to approximately λ / N, and a distance in the measurement axis direction of the second inclined portions is set to It is characterized by being set to λ / (2N) or less.

  According to such a configuration, the reception loop has the contact portions at the pair of apexes at the center position in the measurement axis direction, and the first parallel portion and the first inclination are symmetrically provided on both sides of the contact portion in the measurement axis direction. Part and second parallel part are sequentially formed, and the distance between the centers of the first inclined parts on both sides of the contact part in the measurement axis direction is set to be substantially λ / N, so that the pitch is λ / N. When the magnetic flux coupling member N and the receiving loop move relative to each other, the magnetic flux coupling areas that increase and decrease cancel each other at the first inclined portions on both sides of the contact portion, and generation of harmonics can be suppressed.

  In addition, by configuring both sides of the contact portion as described above, it is possible to prevent interference between adjacent-phase wirings, and further miniaturization can be achieved.

  Furthermore, according to the present invention, the signal strength can be increased to the maximum by setting the distance in the measurement axis direction of the second inclined portion to be λ / (2N) or less.

  According to the present invention, it is possible to provide an inductive displacement detection device with high resolution and high accuracy at low cost.

  Hereinafter, an inductive displacement detector according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the inductive displacement detection device 1 mainly includes a scale 3 and a sensor head 5 disposed so as to face the scale 3. As for the scale 3 in FIG. 1, only a part of longitudinal direction is described. The longitudinal direction of the scale 3 is the measurement axis X. The sensor head 5 is opposed to the scale 3 with a predetermined gap, and is arranged so as to be movable along the measurement axis X. The sensor head 5 may be fixed and the scale 3 may move. That is, the sensor head 5 and the scale 3 only need to be relatively movable in the direction of the measurement axis.

  The scale 3 includes an insulating substrate 7 made of glass epoxy resin. As a material of the insulating substrate 7, glass, silicon, or the like may be used. On the surface of the insulating substrate 7 facing the sensor head 5, a plurality of magnetic flux coupling windings 9 (an example of a magnetic flux coupling member) having the same shape along the measurement axis X are arranged at a predetermined pitch.

  The magnetic flux coupling winding 9 is a rectangular linear conductor whose longitudinal direction is orthogonal to the measurement axis X, and this linear conductor is made of a material having a low electrical resistance such as aluminum, copper, or gold. A passivation film as a protective film (not shown) is formed on the insulating substrate 7 so as to cover the magnetic flux coupling winding 9. Further, instead of the magnetic flux coupling winding 9, a metal plate that inhibits magnetic flux coupling may be periodically arranged along the measurement axis X as a magnetic flux coupling member. Even in such a case, since the periodic signal depending on the position of the sensor head 5 is obtained from the receiving winding 15 as in the case where the magnetic flux coupling winding 9 is arranged, the displacement can be detected.

  The sensor head 5 has an insulating substrate 11 made of glass epoxy resin. Glass, silicon, or the like can be used as the material of the insulating substrate 11. A transmission winding 13 (an example of a transmission member) is formed on the surface of the insulating substrate 11 facing the scale 3. The shape of the transmission winding 13 is a rectangular shape whose longitudinal direction is along the measurement axis X. The transmission winding 13 can be magnetically coupled to the magnetic flux coupling winding 9. Further, instead of the transmission winding 13, one linear conductor may be used as the transmission member.

  A three-phase reception winding 15 is arranged on the surface side and the opposite side (or intermediate layer) of the insulating substrate 11 facing the scale 3 and inside the transmission winding 13. The reception winding 15 can be magnetically coupled to the magnetic flux coupling winding 9 and includes a plurality of reception loops 17 arranged on the insulating substrate 11 along the measurement axis X at a predetermined pitch.

  Next, the three-phase receiving winding 15 will be described in detail with reference to FIG. As shown in FIG. 2B, the reception winding 15 is composed of three reception windings 15a, 15b, and 15c. As shown in FIG. 2A, the reception windings 15a, 15b, and 15c. Are superimposed on each other as shown in FIG. 1 to form a three-phase receiving winding 15. Further, contact portions 16 serving as contact points of a wiring pattern to be described later are formed at the left and right ends and the upper and lower ends of each receiving winding 15a, 15b, 15c. Each reception winding 15 has a pair loop 19 (also referred to as a twisted pair) composed of adjacent reception loops 17. In the following description, the length of the pair loop 19 along the measurement axis X is assumed to be λ. To do. As shown in FIG. 2B, the receiving windings 15a to 15c are shifted from each other by λ / 3 phase. That is, when the phase of the reception winding 15a is set to the reference (0 °), the reception winding 15b is shifted by a λ / 3 phase (120 ° phase) with respect to the reception winding 15a. Further, the reception winding 15c is shifted by 2λ / 3 phase (240 ° phase) with respect to the reception winding 15a.

  Next, the detailed shape of one receiving loop 17 and the shape of the magnetic flux coupling winding 9 with respect to the receiving loop 17 will be described with reference to FIG. As shown in FIG. 3, one receiving loop 17 is connected to an adjacent receiving loop 17 along a first central axis A parallel to the measurement axis X, and is formed symmetrically with respect to the first central axis A. Yes. Each receiving loop 17 has a contact portion 16 such as a through hole or a via hole at a pair of apexes intersecting the second central axis B perpendicular to the first central axis A at the center in the first central axis A direction. Have.

The receiving loop 17 includes a pair of inclined portions 172 (second inclined portions) that cross-connect a pair of opposing portions 171 and 171 including the contact portion 16 and a pair of opposing portions 171 and 171 of the adjacent receiving loop. ). The facing portion 171 includes a first parallel portion 171a ₁ , a first inclined portion 171a ₂ , and a second parallel portion 171b that are sequentially arranged symmetrically on both sides of the contact portion 16 in the measurement axis X direction. The distance between the midpoints of the pair of first inclined portions 171a ₂ is formed to be D = λ / 5. The distance in the measurement axis X direction of the inclined portion 172 is set to S = λ / 10.

  As described above, if the length along the measurement axis X of the pair loop 19 is λ, the length along the measurement axis X of one reception loop 17 is λ / 2, and the pitch of the magnetic flux coupling winding 9 is P is formed so that P = λ / 5. A passivation film (not shown) is formed on the insulating substrate 11 so as to cover the transmission winding 13 and the reception winding 15. Terminals 16 of the transmission winding 13 and the reception winding 15 are connected to an arithmetic / control IC circuit (not shown) for measuring displacement via wiring. The transmission winding 13 and the reception winding 15 are made of the same material as that of the magnetic flux coupling winding 9. The above is the configuration of the inductive displacement detection device 1.

The pitch P and the shape of the pair loop are not limited to the above. If the length of the pair loop is λ, the pitch P is P = λ / N (N is an odd number of 3 or more) and a pair of first loops. The distance D between the midpoints of the first inclined portion 171a ₂ is D = λ / N (N is an odd number greater than or equal to 3), and the distance S of the second inclined portion 172 that is the coupling portion of the adjacent receiving loops 15 is S ≦ λ / It may be 2N (N is an odd number of 3 or more).

  Next, similarly, the operation of the inductive displacement detector 1 will be briefly described with reference to FIG. As shown in FIG. 3, the plan view of each of the transmission winding 13, the magnetic flux coupling winding 9, and the reception winding 15 provided in the inductive displacement detection device 1 and the reception winding generated by the relative movement of the sensor head 5 with respect to the scale 3. A waveform diagram of the output signal H from line 15 is shown.

  A transmission excitation signal (single-layer alternating current) is sent to the transmission winding 13. Thus, when attention is paid to a certain time, the excitation current i1 flows through the transmission winding 13 clockwise. An alternating magnetic flux is generated from the transmission winding 13 by the excitation current i1 and is magnetically coupled to the magnetic flux coupling winding 9. For this reason, the induced current i2 flows in the magnetic flux coupling winding 9 counterclockwise, whereby the alternating magnetic flux generated from the magnetic flux coupling winding 9 is magnetically coupled to the receiving loop 17 of the receiving winding 15. Due to this magnetic flux coupling, a clockwise induced current i3 flows through each receiving loop 17. When the sensor head 5 moves relative to the scale 3, the magnetic flux coupling state of the magnetic flux coupling winding 9 and the receiving loop 17 changes with a moving period of λ / 5.

  Due to the change in the magnetic flux coupling state, the alternating current in the reception loop 17 also changes. That is, since the magnetic flux is supplied from the magnetic flux coupling winding 9, the alternating current flowing through the receiving loop 17 increases as the area of the magnetic flux coupling winding 9 facing the receiving loop 17 increases. . Therefore, if the flow rate of the alternating current in one of the pair loops 19 is large, the direction of the alternating current flowing through the pair loop 19 changes.

  Based on the change of the alternating current flowing through the pair loop 19, the s / 5-wave sine wave output signal H is sent from the receiving winding 15 to the IC circuit (not shown) by the relative movement of the sensor head 5 with respect to the scale 3. The IC circuit samples the output signal H, converts it into a digital value, and calculates the position of the sensor head 5 relative to the scale 3.

  Next, with reference to FIG. 4, the effect of the protrusion 171 included in the reception loop 17 will be described. FIG. 4 is a diagram showing the magnetic flux coupling winding 9 and the receiving winding 15 of the inductive displacement detection device 1 according to the first embodiment of the present invention, and the overlapping portion 23 in which these are opposed and overlapped. The sign of the induced current i3 flowing through one receiving loop 17 (17 ′) forming the pair loop 19 is “+”, and the sign of the induced current i3 flowing through the other receiving loop 17 (17 ″) is “−”. .

  Here, if N is an even number of 2 or more, both the induced current i3 cancel each other by “+” formed by one receiving loop and “−” formed by the other receiving loop. Become. Therefore, as described above, the pitch P must be λ / N (N is an odd number of 3 or more).

As shown in the signal loop 17 ″ on the right side of FIG. 4, when the magnetic flux coupling winding 9 and the receiving winding 15 are positioned symmetrically around the contact portion 16 at a certain time, the magnetic flux coupling winding is considered. The line 9 overlaps the first inclined portion 171a ₂ , and in this case, the total overlapping area of the two magnetic flux coupling windings 9 and the receiving winding 15 is the same regardless of the movement in the measurement axis X direction. This is because the inclination of the pair of first inclined portions 171a ₂ is symmetric and the distance between the pair of first inclined portions 171a ₂ is equal to the distance between the magnetic flux coupling windings 9. For this reason, there is almost no generation of harmonic noise due to the relative movement of the magnetic flux coupling winding 9 and the receiving winding 15 in this portion.

  Next, details of the reception winding 15 (15a, 15b, 15c) arranged on each insulating substrate 11, 11 will be described with reference to FIGS. FIG. 5 is a plan view in which the receiving windings 15 a, 15 b, and 15 c shown in FIG. 2A are divided into the first wiring 31 and the second wiring 33 in each contact portion 16. The divided first wiring 31 is a wiring composed of a portion inclined in an obtuse angle (acute angle) direction with respect to the measurement axis X. The second wiring 33 is a wiring made of a portion inclined in an acute angle (obtuse angle) direction with respect to the measurement axis X.

  For example, in the case of the receiving winding 15a, if the patterns (1) to (10) indicated by solid lines are connected as shown in FIG. 6, the receiving winding 15a is obtained.

  By forming the receiving winding 15 arranged on the front and back of one insulating substrate or on each wiring surface of the two insulating substrates 11 and 11 with a facing portion 171 satisfying a predetermined condition, the contact portion 16 is formed. The wiring can be provided at a location that does not hinder the wiring, and the inclination of the second inclined portion 172 can be increased with respect to the measurement axis X. Therefore, it is possible to provide a high-resolution and high-precision inductive displacement detection device with a single-sided two-layer (both-sided four-layer) substrate without using an expensive manufacturing process such as a high-density buildup substrate or a thin film process. Become.

  As mentioned above, although embodiment of invention was described, this invention is not limited to these, A various change, addition, substitution, etc. are possible within the range which does not deviate from the meaning of invention.

In the above embodiment, the first parallel part 171a ₁ , the first inclined part 171a ₂ and the second parallel part 171b of the facing part 171 of the reception loop 17 are linear, but as shown in FIG. If the receiving loop 17 ′ ″ has a smoothly coupled shape such as a wave shape, the harmonic suppression effect is further improved.

  In the above embodiment, the phases of the three-phase receiving windings are shifted from each other. However, the phase is not limited to three phases, and may be multiphase.

  In the above embodiment, the distance S between the opposing portions is S = λ / 10. However, as shown in FIG. 8, the signal intensity is S = nλ / 5 (n is an integer of 1 or more). As the S is smaller, the signal strength increases. Therefore, S ≦ λ / 10 is preferable.

1 is a perspective view illustrating a schematic configuration of an inductive displacement detection device according to an embodiment of the present invention. It is explanatory drawing of three receiving windings of the induction type displacement detection apparatus which concerns on one Embodiment of this invention. It is explanatory drawing of the structure of one receiving winding of the induction type displacement detection apparatus which concerns on one Embodiment of this invention, the structure of a magnetic flux coupling winding, and those operation | movement. It is a figure which shows the overlap part of one receiving winding of the induction type displacement detection apparatus which concerns on one Embodiment of this invention. It is the top view which decomposed | disassembled the three receiving windings shown to FIG. 2 (A) of the induction type displacement detection apparatus which concerns on one Embodiment of this invention into the 1st layer wiring and the 2nd layer wiring. It is a figure explaining the pattern which comprises one of the three receiving windings shown to FIG. 2 (A) of the induction type displacement detection apparatus which concerns on one Embodiment of this invention. 6 shows a receiving winding of an inductive displacement detector according to another embodiment of the present invention. It is a figure which shows the relationship between the distance S between the opposing parts of this invention, and signal strength.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inductive displacement detection apparatus, 3 ... Scale, 5 ... Sensor head, 7 ... Insulating substrate, 9 ... Magnetic flux coupling winding, 11 ... Insulating substrate, 13 ... Transmission winding, 15, 15a, 15b, 15c ... Reception winding line, 16 ... contact portion, 17 ... receiving loop, 171 ... counter unit, 171a 1 _... first parallel portion, 171a 2 _... first inclined portion, 171b ... second parallel portion, 172 ... inclined portion (second inclined portion) , 19 ... Pair loop, 23 ... Overlapping portion of the reception winding and the magnetic flux coupling winding, 31 ... First wiring, 33 ... Second wiring.

Claims (4)

A scale on which a plurality of magnetic flux coupling members are disposed along the measurement axis;
The transmitter is opposed to the scale and is movable relative to the scale in the measurement axis direction, the transmission winding for supplying magnetic flux to the plurality of magnetic flux coupling members, and the magnetic flux coupling with the magnetic flux coupling members, A sensor head formed with a multi-phase receiving winding composed of a receiving loop forming a pair loop along the measurement axis;
Inductive displacement in which the pitch in the measurement axis direction of the magnetic flux coupling member is set to λ / N (N is an odd number of 3 or more, the same applies hereinafter) where λ is the pitch of the pair loop in the measurement axis direction. In the detection device,
The receive loop is
Formed by a first wiring formed in the first layer and a second wiring formed in the second layer;
A contact portion is formed at a pair of apexes at the center position in the measurement axis direction, and the first wiring and the second wiring are connected via the contact portion so that the wirings of the same layer do not cross each other.
The first and second wirings are
A first parallel portion, a first inclined portion, and a second parallel portion, which are sequentially arranged symmetrically on both sides of the contact portion in the measurement axis direction;
A second inclined portion between the second parallel portion and the second parallel portion of the adjacent receiving loop;
The distance between the centers of the first inclined portions on both sides of the contact portion in the measurement axis direction is set to approximately λ / N,
A distance in the measurement axis direction of the second inclined portion is set to λ / (2N) or less.   The inductive displacement detection device according to claim 1, wherein the first parallel portion, the first inclined portion, and the second parallel portion are smoothly connected.   2. The inductive displacement detecting device according to claim 1, wherein the receiving winding is a three-phase receiving winding whose pitch is shifted by [lambda] / 3.   2. The inductive displacement detection device according to claim 1, wherein the magnetic flux coupling members are arranged at a pitch of [lambda] / 5 in the measurement axis direction of the scale.

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