JP2004061498A - Induction type position detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction type position detector that can reduce a cross-talk. <P>SOLUTION: A first coupling loop 35 and a second coupling loop 37 are connected electrically with each other by the third wiring 39 in a cross section different from that of the figure, on the scale 3 side of this induction type position detector. A first wiring 55 connected electrically to a transmission coil and second wirings 56 and 58 connected electrically to a reception coil are covered respectively with shield films 52 and 54, on the reading head 5 side of the induction type position detector. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inductive position detecting device that performs position detection using electromagnetic coupling.
[0002]
[Prior art]
Conventionally, this type of inductive type position detecting device has a scale in which magnetic flux coupling windings are arranged at a predetermined pitch, and a transmission winding which is disposed so as to be relatively movable with respect to the scale and electromagnetically coupled with the magnetic flux coupling winding. And a read head on which the receiving winding is arranged. Then, the magnetic flux coupling winding of the scale is coupled with the variable magnetic flux generated by the transmission winding of the read head and the first coupling loop through which the induced current flows, and the induced current from the first coupling loop flows, thereby A second coupling loop that couples the generated variable magnetic flux to the receiving winding of the read head (for example, Patent Document 1).
[0003]
[Patent Document 1]
JP-A-10-318781 (FIG. 1)
[0004]
[Problems to be solved by the invention]
There are two problems with inductive position detection devices. One is an increase in crosstalk, and the other is an increase in impedance of the transmission winding. First, the first problem will be described.
[0005]
As described above, the variable magnetic flux from the second coupling loop is coupled to the receiving winding. The variable magnetic flux is converted into a reception signal by a reception winding and sent to a predetermined circuit via a wiring. When this wiring couples with the variable magnetic flux generated in the transmission winding, crosstalk occurs in this wiring.
[0006]
Also, by passing the transmission excitation signal through the transmission winding, a variable magnetic flux coupled to the first coupling loop is generated at the transmission winding. Since the transmission excitation signal is guided to the transmission winding via the wiring, a variable magnetic flux is inevitably generated from this wiring. Since this wiring does not face the first coupling loop, the variable magnetic flux generated from this wiring cannot be used for position detection. Therefore, when this variable magnetic flux is coupled to, for example, the first coupling loop, crosstalk occurs in the first coupling loop.
[0007]
The crosstalk as described above causes an offset, and thus the accuracy of position detection is reduced. In order to prevent crosstalk, the wiring connected to the reception winding is routed to a position far from the transmission winding and connected to the predetermined circuit, and the knitting method of the wiring is devised to produce a crosstalk cancellation effect. Countermeasures such as that can be considered. However, there are disadvantages such as an increase in the wiring length and the complexity of the wiring.
[0008]
Next, another problem, that is, an increase in the impedance of the transmission winding will be described. The transmission winding includes a parallel portion parallel to the measurement axis and a crossing intersection. The variable magnetic flux generated in the parallel portion is coupled to a first coupling loop forming a magnetic flux coupling winding of the scale. Therefore, the variable magnetic flux generated at the parallel portion is used for position detection, and the variable magnetic flux generated at the intersection is not used. The crossing cannot be omitted in configuring the transmission winding. Since the variable magnetic flux is also generated at the intersection, the impedance of the transmission winding increases by that much, and the current of the transmission winding decreases. As a result, the variable magnetic flux generated by the transmission winding is weakened, which hinders accurate position detection.
[0009]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an inductive position detecting device capable of reducing crosstalk. It is another object of the present invention to provide an inductive position detecting device capable of reducing the impedance of a transmission winding.
[0010]
[Means for Solving the Problems]
(1) One of the inductive position detecting devices according to the present invention is an inductive position detecting device including a scale on which a magnetic flux coupling winding is disposed, and a read head disposed so as to be movable relative to the scale. The detection device, wherein the read head includes: a transmission winding that generates a variable magnetic flux coupled to the magnetic flux coupling winding; a reception winding to which the variable magnetic flux from the magnetic flux coupling winding is coupled; and a transmission winding. , A second wiring electrically connected to the receiving winding, and readout so as to cover this wiring before and after at least one of the first and second wirings when viewed from the scale. And a shield film disposed on the head and configured of at least one of a magnetic film and a conductive film.
[0011]
According to one of the inductive position detecting devices according to the present invention, the shield film is disposed so as to cover at least one of the first and second wirings before and after the wiring when viewed from the scale. Therefore, since this wiring is shielded, crosstalk caused by this wiring can be reduced.
[0012]
(2) In one of the induction-type position detection devices, the magnetic flux coupling winding includes a first coupling loop through which a variable magnetic flux generated by the transmission winding is coupled and an induction current flows, and a variable magnetic flux generated by the induction current. And a third wiring for electrically connecting the first and second coupling loops, and a scale is provided on the front and rear sides of the third wiring when viewed from the read head. Another shield film that is arranged on the scale so as to cover the third wiring and that is configured of at least one of the magnetic film and the conductive film can be included.
[0013]
According to this, since the third wiring is shielded, crosstalk caused by this wiring can be reduced.
[0014]
(3) In one of the inductive position detecting devices, at least one of the shield film and the other shield film may include a stacked structure in which a magnetic film and a conductive film are stacked.
[0015]
According to this, the high permeability and the high saturation magnetic flux density required as the properties of the shield film (the shield film and the other shield films) are satisfied by the function of the magnetic film, and the low electric resistance is satisfied by the function of the conductive film. be able to.
[0016]
(4) In one of the inductive position detecting devices, the thickness of at least one of the shield film and the other shield film is substantially the same as the skin depth of the film, and May have a laminated structure of a plurality of the above films.
[0017]
According to this, a shield effect is generated in each of the films (at least one of the shield film and the other shield film) constituting the laminated structure, so that the shield effect is increased as a whole of the laminated structure. Therefore, crosstalk can be further reduced.
[0018]
(5) In one of the above-described inductive position detecting devices, the laminated structure is such that magnetic films and conductive films are alternately laminated, and the thickness of the magnetic film is substantially the same as the skin depth of the magnetic film. The thickness of the conductive film may be substantially the same as the skin depth of the conductive film.
[0019]
According to this, the shield effect can be increased while satisfying the conditions of high magnetic permeability, high saturation magnetic flux density, and low electric resistance required as characteristics of the shield film.
[0020]
(6) Another one of the inductive type position detecting devices according to the present invention includes a scale on which a magnetic flux coupling winding is arranged, and a read head arranged to be relatively movable with respect to the scale along a measurement axis. Wherein the read head includes a transmission winding for generating a variable magnetic flux coupled to the magnetic flux coupling winding, and an intersection of the transmission windings extending in a direction intersecting the measurement axis. And a shield film that is disposed on the read head so as to cover the front and rear sides when viewed from the scale, and that is configured by at least one of a magnetic film and a conductive film.
[0021]
According to another one of the inductive position detecting devices according to the present invention, since the crossing portion of the transmission winding is covered with the shield film, the generation of the variable magnetic flux at the crossing portion can be prevented (or suppressed). The impedance of the transmission winding can be reduced.
[0022]
(7) In another one of the inductive type position detection devices, the read head includes a first wiring electrically connected to the transmission winding, and the shield film is provided on the front and rear sides when the first wiring is viewed from the scale. It can be arranged so as to cover the read head.
[0023]
According to this, since the first wiring is covered with the shield film, generation of the variable magnetic flux in the first wiring can be prevented (or suppressed). Note that (3), (4), and (5) also apply to another one of the above-described guidance-type position detection devices.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view illustrating a schematic configuration of the guidance-type position detection device 1 according to the first embodiment. The inductive position detecting device 1 is also called an inductive encoder, and includes a scale 3 and a read head 5 (also called a transducer) arranged to face the scale 3. The longitudinal direction of the scale 3 is the measurement axis x. The read head 5 is disposed so as to be relatively movable in the measurement axis x direction with a predetermined gap with respect to the scale 3.
[0025]
The read head 5 has an insulating substrate 51. On the surface 51A of the insulating substrate 51 facing the scale 3, a rectangular transmission winding 53 whose longitudinal direction is the x direction, a first wiring 55 electrically connected thereto, and terminals 55A and 55B of the wiring 55 Is arranged. On the side of the surface 51A of the insulating substrate 51 and adjacent to the transmission winding 53, reception windings 57 and 59 having a predetermined number of turns, second wirings 56 and 58 electrically connected to each of them, and second wirings The 56 terminals 56A and 56B and the terminals 58A and 58B of the second wiring 58 are arranged. The receiving windings 55 and 57 are arranged so as to be insulated from each other and overlap each other.
[0026]
In the first embodiment, crosstalk is reduced by arranging a shield film (not shown in FIG. 1) covering the first wiring 55 and the second wirings 56 and 58 on the read head 5. This will be described later in detail. In FIG. 1, the surface 51A and the surface 51A are shown for convenience of expressing the transmission winding 53, the first wiring 55, the terminals 55A and 55B, the receiving windings 57 and 59, the second wirings 56 and 58, and the terminals 56A, 56B, 58A and 58B. It is drawn on the opposite side.
[0027]
On the other hand, the scale 3 has a large number of magnetic flux coupling windings 33 arranged along the insulating substrate 31 and the surface 31A of the substrate 31 facing the read head 5 along the x direction at a scale pitch λ. The magnetic flux coupling winding 33 includes a first coupling loop 35 disposed so as to face the transmission winding 53, a second coupling loop 37 disposed so as to face the reception windings 57 and 59, and a first coupling loop. It is constituted by a loop 35 and a third wiring 39 for electrically connecting the second coupling loop 37. In the first embodiment, a crosstalk is reduced by disposing a shield film (not shown in FIG. 1) on the scale 3 so as to cover the third wiring 39. This will be described later in detail.
[0028]
Here, the two receiving windings 57 and 59 will be described in detail. The receiving windings 57 and 59 are arranged so as to overlap each other. FIG. 2 shows these separately. The receiving windings 57, 59 are formed with a sinusoidal periodic pattern of wavelength λ for spatially modulating the coupling of the magnetic flux from the second coupling loop 37 of FIG. The receiving windings 57 and 59 are arranged with a phase shifted from each other by a quarter of the scale pitch λ.
[0029]
Each of the receiving windings 57 and 59 has a first conductor segment 61 indicated by a solid line, a second conductor segment 63 indicated by a broken line formed on a layer different from the first conductor segment 61, and a through wiring 65 electrically connecting these segments. It consists of. The receiving winding 57 forms two loops 57A and 57B within one wavelength λ, and the receiving winding 59 forms two loops 59A and 59B.
[0030]
Referring to FIGS. 1 and 2, when the scale 3 moves and the loop 57A and the second coupling loop 37 show the maximum electromagnetic coupling with the movement of the scale 3, the loop 57B and the second coupling loop 37 shows the variation of the coupling such that the minimum coupling is between 37. That is, the fluctuating magnetic field formed by the arrangement of the second coupling loops 37 is spatially modulated by the shape of the receiving winding 57 as the scale 3 moves, and the sinusoidal waves are applied to the terminals 56A and 56B via the second wiring 56. Is obtained. The receiving winding 59 is the same as the receiving winding 57, and sinusoidal displacement signals whose phases are shifted by λ / 4 are obtained at the terminals 58A and 58B.
[0031]
Next, the operation of the guidance-type position detection device 1 will be briefly described with reference to FIG. The transmission excitation signal (single-phase alternating current) generated by the generation circuit 7 which is an IC circuit is sent from the terminals 55A and 55B to the transmission winding 53 via the first wiring 55. As a result, when focusing on a certain time, the exciting current i1 flows counterclockwise through the transmission winding 53. Then, a variable magnetic flux is generated from the transmission winding 53 by the excitation current i1 and is coupled to the first coupling loop 35. More specifically, the winding conductor portions 53A and 53B, which are portions of the transmission winding 53 in the measurement axis x direction, face and face the winding conductor portions 35A and 35B constituting the first coupling loop 35 in parallel. Magnetic coupling. Thus, the induced current i2 flows through the first coupling loop 35. The induced current i2 flows through the third wiring 39 as the current i3 to the second coupling loop 37. As a result, the variable magnetic flux generated from the second coupling loop 37 is coupled to the receiving windings 57 and 59. Then, the sinusoidal displacement signal described with reference to FIG. 2 is sent to the processing circuit 8 (IC circuit) via the terminals 56A, 56B, 58A, and 58B as a reception signal. The processing circuit 9 samples these received signals, converts them into digital values, and sends them to the arithmetic and control circuit 9 (IC circuit). The arithmetic control circuit 9 calculates the position of the read head 5 with respect to the scale 3 based on the digital value. The operation control circuit 9 also has a function of controlling the generation circuit 7.
[0032]
As described above, in the first embodiment, the crosstalk is reduced by providing the shield film that covers each of the first wiring 55, the second wirings 56 and 58, and the third wiring 39. This will be described in detail below. First, the planar positional relationship of the shield film will be described. FIG. 3 is a perspective view of the read head 5 of FIG. The shield films 52 and 54 extend in a direction intersecting the x direction, and are formed on the read head 5 so as to cover the first wiring 55 and the second wirings 56 and 58 from above and below. FIG. 4 is a perspective view of the scale 3 of FIG. The shield films (other shield films) 32 and 34 extend in the x direction, and are formed on the scale 3 so as to cover the third wiring 39 of each magnetic flux coupling winding 33 from above and below.
[0033]
Next, the sectional positional relationship of the shield film will be described. FIG. 5 is a sectional view taken along line V (a) -V (b) of FIG. 1, and FIG. 6 is a sectional view taken along line VI (a) -VI (b) of FIG. First, a cross section on the read head 5 side will be described with reference to FIGS. The insulating substrate 51 of the read head 5 includes a semiconductor substrate 69 made of silicon or the like covered with an insulating film 67 such as a silicon oxide film. The shield film 52 is formed on the entire surface of the insulating film 67 in the cross section shown in FIG. 5, while the shield film 52 is not formed in the cross section shown in FIG. An insulating film 71 such as a silicon oxide film or a polyimide film is formed on the insulating film 67 so as to cover the shield film 52.
[0034]
In the cross section shown in FIG. 5, the first wiring 55 and the second wirings 56 and 58 are arranged on the insulating film 71 at a distance from each other. On the other hand, in the cross section shown in FIG. 6, the transmission winding 53 and the second conductor segment 63 (FIG. 2) are arranged on the insulating film 71 at a distance from each other. An insulating film 73 made of the same material as the insulating film 71 is formed so as to cover them. The first conductor segment 61 (FIG. 2) is arranged on the insulating film 73 so as to face the second conductor segment 63 in the cross section shown in FIG. The first conductor segment 61 is electrically connected to the second conductor segment 63 by a through-hole 65 (FIG. 2) embedded in a through hole of the insulating film 73.
[0035]
An insulating film 75 made of the same material as the insulating film 71 is formed on the insulating film 73 so as to cover the first conductor segment 61. In the cross section shown in FIG. 5, the shield film 54 is disposed on the entire surface of the insulating film 75. Then, a protective film 77 such as a silicon oxide film is formed on the insulating film 75 so as to cover the shield film 54.
[0036]
On the other hand, on the scale 3 side, the cross-sectional structures of FIGS. 5 and 6 are the same. The insulating substrate 31 includes a semiconductor substrate 43 made of silicon or the like covered with an insulating film 41 such as a silicon oxide film, like the insulating substrate 51. On the insulating film 41, the shield film 32 is selectively disposed. An insulating film 45 such as a silicon oxide film or a polyimide film is formed on the insulating film 41 so as to cover the shield film 32. A third wiring 39 is disposed on the insulating film 45 so as to face the shield film 32, and a first coupling loop 35 and a second coupling loop 37 are disposed on both sides of the wiring. An insulating film 47 made of the same material as the insulating film 45 is formed on the insulating film 45 so as to cover them. Then, the shield film 34 is selectively formed on the insulating film 47 so as to face the third wiring 39. A protective film 49 such as a silicon oxide film is formed on the insulating film 47 so as to cover the shield film 34.
[0037]
As described above, in the first embodiment, the first wiring 55 and the second wirings 56 and 58 are respectively covered with the shield films 52 and 54 from above and below. In other words, the shield films 52 and 54 are arranged on the front and rear sides of these wirings as viewed from the scale 3 so as to cover these wirings. Similarly, the third wiring 39 is also covered by the shield films 32 and 34 from above and below (in other words, the shield films 32 and 34 are arranged on the front and rear sides of the third wiring 39 as viewed from the read head 5 so as to cover the wirings. There).
[0038]
The shielding effect of these shield films will be described. The transmission excitation signal generated by the generation circuit 7 shown in FIG. 1 is sent to the transmission winding 53 via the first wiring 55, and a variable magnetic flux is generated from the transmission winding 53. At this time, a variable magnetic flux is inevitably generated from the first wiring 55 as well. This variable magnetic flux is not used for position detection. When the variable magnetic flux is coupled to the reception windings 57 and 59, the transmission winding 53, and the magnetic flux coupling winding 33 (hereinafter referred to as a winding), crosstalk occurs in these windings. . However, in the first embodiment, since the upper and lower portions of the first wiring 55 are covered with the shield films 52 and 54, the coupling of the variable magnetic flux generated in the first wiring 55 with the winding can be reduced. .
[0039]
On the other hand, when the variable magnetic flux generated by the transmission winding 53 is coupled to the second wirings 56, 58 and the third wiring 39, crosstalk occurs in these wirings. However, since the upper and lower portions of the second wires 56 and 58 are covered with the shield films 52 and 54 and the upper and lower portions of the third wire 39 are covered with the shield films 32 and 34, the variable magnetic flux generated in the transmission winding 53 is formed. Can be reduced with these wirings.
[0040]
As described above, in the first embodiment, the upper and lower portions of each of the first wiring 55, the second wirings 56 and 58, and the third wiring 39 are covered with the shield film, so that the crosstalk can be reduced. As a result, The measurement accuracy can be improved.
[0041]
In the first embodiment, it is desired that the shield film has the following characteristics: (1) high magnetic permeability, (2) low coercive force, (3) high saturation magnetic flux density, and (4) low electric resistance. When the shield film is a film (magnetic film) made of a magnetic material such as iron, it has a higher magnetic permeability and a higher saturation magnetic flux density than air, so that a magnetic shield effect is generated. This can reduce the coupling of the variable magnetic flux with the winding and the wiring. Particularly, a soft magnetic material (for example, Fe-Ni permalloy or amorphous metal) is preferable. This is because the soft magnetic material has a low coercive force, and if the variable magnetic flux disappears, the magnetic field of the shield film tends to change, so that the influence of the magnetization by the variable magnetic flux hardly remains on the shield film.
[0042]
On the other hand, when the shield film has a low electric resistance such as a conductive film (for example, a metal film containing copper, aluminum, or gold), an eddy current generated when the variable magnetic flux passes through the shield film becomes large, and a current loss effect occurs. Can be improved. As a result, the variable magnetic flux is weakened, so that the coupling of the variable magnetic flux with the winding and the wiring can be reduced.
[0043]
The shield film may be either a magnetic film or a conductive film. In particular, a combination of a magnetic film and a conductive film is preferable because all of the above conditions (1) to (4) are satisfied. This combined structure is shown in FIG. 7 as a modification of the first embodiment. FIG. 7 is a sectional view corresponding to FIG. The same elements as those indicated by the reference numerals in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted. In this modified example, the shield films 32, 34, 52, and 54 are two layers of a magnetic film 81 and a conductive film 83.
[0044]
Further, the shield films 32, 34, 52, 54 may have the structure shown in FIG. FIG. 8 is a sectional view of this structure. It has a structure in which shield films 91 (magnetic film or conductive film) and insulating films 93 are alternately stacked. In the case of a high frequency, a skin effect occurs in the magnetic film and the conductive film. That is, the lines of magnetic force (variable magnetic flux) mainly pass through the surface layer of the magnetic film, and the current (eddy current) mainly flows through the surface layer of the conductive film. For this reason, even if the thickness of the shield film is increased, the shield effect (magnetic shield effect or current loss effect due to eddy current) does not increase accordingly, and portions that do not contribute to the shield effect are wasted. Therefore, in the example of FIG. 8, the thickness of the shield film 91 is made substantially the same as the skin depth of the shield film 91 (the depth from the surface where the skin effect occurs). The term “substantially the same” includes not only the same case but also a slight difference such as an error. The skin depth δ is generally expressed as follows.
[0045]
δ = (2 / μσω)^1/2
Here, μ is the permeability of the shield film, σ is the conductivity of the shield film, and ω is the angular frequency of the excitation current i1 (FIG. 1) flowing through the transmission winding 53.
[0046]
FIG. 8 shows a structure in which shield films 91 having a thickness substantially equal to the skin depth are alternately laminated with an insulating film 93 such as a silicon oxide film, that is, a laminated structure of a plurality of shield films 91. Therefore, a shield effect (a magnetic shield effect or a current loss effect due to an eddy current) occurs in each shield film 91, so that the shield effect can be increased in the entire structure shown in FIG. As a result, crosstalk can be further reduced. In FIG. 8, the shield films 91 are separated from each other by disposing an insulating film 93 between the shield films 91. If a skin effect occurs in each shield film 91, the insulating film 93 may not be provided, and another film other than the insulating film 93 may be provided.
[0047]
Further, a structure in which shield films each having a thickness equal to the skin depth may be stacked as shown in FIG. In this structure, the thickness of the magnetic film 95 and the conductive film 97 is substantially the same as the skin depth, and the magnetic film 95 and the conductive film 97 are alternately stacked. According to this, the shielding effect can be increased while satisfying the above conditions (1) to (4).
[0048]
As shown in FIG. 5, in the first embodiment, each of the first wiring 55, the second wirings 56 and 58, and the third wiring 39 is covered with a shield film from above and below. However, the present invention is not limited to this, and any structure may be used as long as at least one of the first wiring 55 and the second wirings 56 and 58 is covered with a shield film from above and below. Although the silicon substrates covered with the insulating film are used as the insulating substrates 31 and 51 (FIG. 5), a glass substrate, a ceramic substrate, and a resin substrate can be used. The present invention is also effective when the read head and the scale are formed by a printed circuit board.
[0049]
[Second embodiment]
Next, a second embodiment of the present invention will be described focusing on differences from the first embodiment. In the drawings for explaining the second embodiment, the same components as those shown by the reference numerals in the drawings already described are denoted by the same reference numerals, and description thereof will be omitted. FIG. 10 is a diagram in which a transmission winding 53 and shield films 52 and 54 are extracted from the inductive position detection device according to the second embodiment. The second embodiment is characterized in that shield films 52 and 54 are arranged so as to cover the intersections 53C and 53D of the first wiring 55 and the transmission winding 53. Thereby, the impedance of the transmission winding 53 is reduced. Hereinafter, details of the second embodiment will be described.
[0050]
The transmission winding 53 is rectangular and includes parallel portions 53A and 53B that are parallel to the measurement axis x and crossing portions 53C and 53D that intersect. In the first embodiment, the reference numerals 53A and 53B are the winding conductors, but in the second embodiment they are the parallel parts. The shield films 52 and 54 are disposed on the read head 5 (FIG. 1) so as to cover the intersections 53C and 53D and the first wiring 55 on the front and rear sides thereof when viewed from the scale 3 (FIG. 1). The layers on which the shield films 52 and 54 are arranged are as shown in FIG. 5 of the first embodiment, and the materials of the shield films 52 and 54 are the same as those of the first embodiment.
[0051]
The effect of the second embodiment will be described. FIG. 11 is a diagram showing the transmission winding 53 without the shield films 52 and 54, and shows a magnetic field generated from the transmission winding 53 and the first wiring 55 at a certain time. The magnetic field (variable magnetic flux) generated by the parallel portions 53A and 53B is coupled to the first coupling loop 35 (FIG. 1). Therefore, the magnetic field generated at the parallel portions 53A and 53B is used for position detection, and the magnetic field generated at the intersections 53C and 53D is not used.
[0052]
Focusing on this point, in the second embodiment, the intersections 53C and 53D are covered with the shield films 52 and 54. FIG. 12 is a diagram showing a state where a magnetic field is generated in the configuration shown in FIG. The generation of the eddy current in the shield films 52 and 54 prevents (or suppresses) the generation of the magnetic field from the intersections 53C and 53D. This means that the inductance of the transmission winding 53 decreases. This is because the inductance L is defined by a magnetic field generated by a current per 1 A, and thus the inductance L decreases as the total magnetic flux generated decreases.
[0053]
Since the impedance Z of the circuit including the transmission winding 53 and the first wiring 55 is as follows, when the inductance L decreases, the impedance Z also decreases. R is the resistance of this circuit, and L is the inductance of the transmission winding 53.
[0054]
Z = (R²+ Ω²L²)^1/2
[0055]
When the impedance Z decreases, the current flowing through the transmission winding 53 increases, so that the magnetic field (variable magnetic flux) generated by the parallel portions 53A and 53B increases. Therefore, the signal strength detected by the first coupling loop 35 (FIG. 1) of the magnetic flux coupling winding 33, and eventually by the receiving windings 57 and 59 (FIG. 1) can be increased, so that the accuracy of position measurement can be improved. .
[0056]
Since the first wiring 55 is also covered with the shield films 52 and 54, the magnetic field generated by the first wiring 55 is also prevented (or suppressed). Therefore, for the same reason as the intersections 53C and 53D, the signal strength detected by the reception windings 57 and 59 can be increased, and the accuracy of position measurement is improved. Since the first wiring 55 is covered with the shield films 52 and 54, crosstalk can be suppressed as described in the first embodiment.
[0057]
【The invention's effect】
As described above, according to one of the guidance-type position detecting devices according to the present invention, crosstalk can be reduced, and thereby, the accuracy of position detection can be improved. Further, according to another one of the inductive position detecting devices according to the present invention, the impedance of the transmission winding can be reduced, so that the current flowing through the transmission winding can be increased. As a result, the accuracy of position detection can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a schematic configuration of a guidance-type position detection device according to a first embodiment.
FIG. 2 is a diagram illustrating a configuration of a receiving winding of the first embodiment.
FIG. 3 is a perspective view of the read head shown in FIG.
FIG. 4 is a perspective view of the scale shown in FIG. 1;
FIG. 5 is a sectional view taken along line V (a) -V (b) of FIG. 1;
FIG. 6 is a sectional view taken along line VI (a) -VI (b) of FIG. 1;
FIG. 7 is a sectional view of a modification of the guidance-type position detection device according to the first embodiment.
FIG. 8 is a sectional view of a modified example of the shield film provided in the first embodiment.
FIG. 9 is a cross-sectional view of another modified example of the shield film provided in the first embodiment.
FIG. 10 is a diagram in which a transmission winding and a shield film are extracted from the inductive position detection device according to the second embodiment.
FIG. 11 is a diagram illustrating a transmission winding without a shield film, and illustrates a magnetic field generated from the transmission winding and the like at a certain time;
FIG. 12 is a diagram corresponding to FIG. 11 and showing a transmission winding in a state where a shield film is provided;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inductive position detecting device, 3 ... Scale, 5 ... Read head, 31 ... Insulating substrate, 32 ... Shield film, 33 ... Magnetic flux coupling winding, 34 ... Shield film, 35: first coupling loop, 37: second coupling loop, 39: third wiring, 51: insulating substrate, 52: shield film, 53: transmission winding 53A, 53B ... winding conductor part (parallel part), 53C, 53D ... crossing part, 54 ... shield film, 55 ... first wiring, 56 ... second wiring, 57 ... ..Reception winding, 58 ... Second wiring, 59 ... Reception winding, 81 ... Magnetic film, 83 ... Conducting film, 91 ... Shield film, 93 ... Insulating film, 95: magnetic film, 97: conductive film

Claims (10)

An inductive position detection device comprising: a scale on which a magnetic flux coupling winding is arranged; and a read head arranged to be movably opposed to the scale,
The read head includes:
A transmission winding that generates a variable magnetic flux coupled to the magnetic flux coupling winding;
A receiving winding to which a variable magnetic flux from the magnetic flux coupling winding is coupled;
A first wiring electrically connected to the transmission winding;
A second wiring electrically connected to the receiving winding;
A shield film disposed on the read head so as to cover the wiring on the front and rear sides of at least one of the first and second wirings when viewed from the scale, and formed of at least one of a magnetic film and a conductive film; When,
An inductive type position detecting device comprising: The magnetic flux coupling winding,
A first coupling loop in which a variable magnetic flux generated by the transmission winding is coupled and an induced current flows;
A second coupling loop coupling the variable magnetic flux generated by the induced current to the reception winding;
A third wiring that electrically connects the first coupling loop and the second coupling loop;
Including
The scale is
The magnetic head further includes another shield film disposed on the scale so as to cover the third wiring on the front and rear sides of the third wiring as viewed from the read head, and configured of at least one of a magnetic film and a conductive film. The guidance-type position detection device according to claim 1, wherein 3. The inductive position detecting device according to claim 1, wherein at least one of the shield film and the other shield film has a laminated structure in which a magnetic film and a conductive film are laminated. The thickness of at least one of the shield film and the other shield film is substantially the same as the skin depth of the film,
The guidance-type position detection device according to claim 1, wherein the guidance-type position detection device has a stacked structure of a plurality of the films. The laminated structure is obtained by alternately laminating the magnetic film and the conductive film,
The thickness of the magnetic film is substantially the same as the size of the skin depth of the magnetic film,
4. The inductive position detecting device according to claim 3, wherein the thickness of the conductive film is substantially the same as the skin depth of the conductive film. An inductive position detection device comprising: a scale on which a magnetic flux coupling winding is arranged; and a read head arranged so as to be relatively movable along the measurement axis with respect to the scale,
The read head includes:
A transmission winding that generates a variable magnetic flux coupled to the magnetic flux coupling winding;
A shield that is disposed on the read head and covers at least one of a magnetic film and a conductive film so as to cover an intersecting portion of the transmission winding extending in a direction intersecting with the measurement axis on the front and rear sides as viewed from the scale. A membrane,
An inductive type position detecting device comprising: The read head includes a first wiring electrically connected to the transmission winding,
7. The inductive position detecting device according to claim 6, wherein the shield film is disposed on the read head so as to cover the first wiring on the front and rear sides when viewed from the scale. 8. The inductive position detecting device according to claim 6, wherein the shield film has a laminated structure in which a magnetic film and a conductive film are laminated. The thickness of the shield film is substantially the same as the size of the skin depth of the film,
The guidance-type position detection device according to claim 6, wherein the guidance-type position detection device has a stacked structure of a plurality of the films. The laminated structure is obtained by alternately laminating the magnetic film and the conductive film,
The thickness of the magnetic film is substantially the same as the size of the skin depth of the magnetic film,
9. The inductive position detecting device according to claim 8, wherein the thickness of the conductive film is substantially the same as the skin depth of the conductive film.

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