Inductive position detector

Abstract

An inductive position detector (100) includes: a stator (1) having a wiring board (10); a rotor (2) that has a non-conductor member (21) disposed facing the stator (1) and that rotates relative to the stator (1) about a rotation axis (3a); a conductor pattern (T) held on the non-conductor member (21), having a geometric periodicity in the circumferential direction about the rotation axis (3a), moving through a rotation orbit about the rotation axis (3a) as the rotor (2) rotates; and a plurality of chip inductors (L) which are disposed so as to face the rotation track with different spatial phases with respect to the conductor pattern (T), are surface-mounted on the main surface of the wiring board (10) of the stator (1), and constitute a plurality of detection coils for detecting changes in the magnetic field accompanying the passage of the conductor pattern (T), respectively.

Description

Related Applications

[0001] This application claims priority based on Japanese Patent Application No. 2022-95845 filed on June 14, 2022, and all the contents of that application are incorporated into this application. Technical Field

[0002] The present invention relates to an inductive position detector. Background Art

[0003] As position detectors for detecting the rotational position, various detection methods are used, such as optical, magnetic, electrostatic capacitance, rotary transformer, and inductive. The inductive position detector moves the movable part holding the conductor in the AC magnetic field and detects the change in the magnetic field caused by the current induced in the conductor. The inductive position detector is not easily affected by garbage, dirt, and external magnetic fields, so it has excellent environmental resistance. In addition, the structure is simple, miniaturization and thinness can be achieved, and the cost is relatively low.

[0004] Inductive position detectors are disclosed in Patent Documents 1 to 4, for example.

[0005] Patent Documents 1 and 4 disclose a structure in which an excitation coil and a detection coil are formed by a conductor pattern on a printed wiring board, and a conductor target is moved relative to the detection coil. The voltage induced in the detection coil by the AC magnetic field generated by the excitation coil changes according to the positional relationship between the detection coil and the conductor target. Thus, the position of the conductor target can be detected.

[0006] Patent Document 2 discloses a structure in which a detection coil is formed by a conductor pattern on a printed wiring board, an AC voltage is applied to the detection coil, and a change in inductance of the detection coil is detected when a conductor target moves relative to the detection coil.

[0007] Patent Document 3 discloses a structure in which an excitation coil and a detection coil are formed by a conductor pattern on a silicon substrate. The detection principle is the same as that of Patent Documents 1 and 4. Prior art literature Patent Literature

[0008] Patent Document 1: Japanese Patent Publication No. 61-159101 Patent Document 2: Japanese Patent No. 5226694 Patent Document 3: Japanese Patent No. 5300164 Patent Document 4: Japanese Patent Application Publication No. 2021-56176 Patent Document 5: Japanese Patent Application Publication No. 2000-49014 Summary of the invention Technical problem to be solved by the invention

[0009] In position detectors that detect rotational position, size, resolution, and accuracy are very important performances. The number of detection cycles per rotation is called the axis angle. One conductor target passes through one detection coil, thereby obtaining a detection signal of one cycle. The more axis angles there are, the higher the resolution is, and the easier it is to improve the accuracy. In order to increase the axis angle, it is necessary to increase the number of conductor targets arranged on the circumference around the axis of rotation. Therefore, in order to achieve a smaller size and higher resolution and accuracy position detector, it is necessary to refine the spacing of the conductor targets.

[0010] When the distance between the conductor targets becomes finer, the detection coil also needs to be smaller accordingly. When the detection coil becomes smaller, the cross-link magnetic flux decreases, so the detected signal voltage becomes smaller. As a result, the signal-to-noise ratio (S / N ratio) decreases, making it difficult to perform accurate position detection. Therefore, it is desirable to increase the number of turns of the detection coil as much as possible to ensure sufficient signal voltage.

[0011] When forming the detection coil using the conductor pattern on the printed wiring board, the additional cost is low because the signal processing circuit can be formed on the same printed board. In addition, the printed circuit board is suitable for high-variety and low-volume production because the initial cost for production is low, and a high degree of design freedom is possible.

[0012] In FIG. 52 of Patent Document 1 and FIG. Fig. 9 , and the like. Examples of making detection coils using conductor patterns on printed wiring substrates are shown in FIG. They all form detection coils using spiral conductor patterns. If you want to increase the number of turns, you can use a structure that uses a multilayer printed wiring board and connects spiral conductor patterns formed on multiple wiring layers via through holes. However, due to limitations such as pattern width, pattern spacing, and through-hole diameter, it is difficult to make small coils with a large number of turns. Increasing the number of wiring layers to increase the number of turns will increase costs.

[0013] If a conductor pattern is formed on a silicon substrate using a semiconductor manufacturing process as in Patent Document 3, the pattern width, pattern spacing, through-hole diameter, etc. can be finer than a printed wiring substrate, so a very small detection coil can be made. However, the semiconductor manufacturing process not only requires a large amount of initial cost, but also has a low degree of freedom and is not suitable for small-scale production of multiple varieties. In addition, due to the size limitation of the silicon substrate, the detection coils need to be centrally arranged. Therefore, the detection becomes a part of the circumference around the axis of rotation. If multiple elements are used, detection can be performed at positions evenly distributed on the circumference, but due to cost issues, the design cannot be realized.

[0014] As coil shapes other than the spiral shape, a detection coil shape in which a pattern is crossed in an 8-shaped pattern to form a loop is proposed, as shown in FIG. 15 of Patent Document 1, and a detection coil shape in which a pattern is crossed in an 8-shaped pattern to form a loop is proposed, as shown in FIG. Figure 2 The zigzag shape with the Bonya effect is shown in the figure. Regardless of the coil shape, the portion surrounded by the advancing and returning patterns forms a coil of one turn. By multiplexing the advancing and returning patterns, the number of turns can be more than one turn, but it is difficult to make a coil with a large number of turns in a size that can be arranged on a small pitch between the conductor targets. In addition, in order to detect the rotation position, it is preferable to set more than two detection coils that output signals with different phases. However, in the pattern of the figure 8 or the zigzag shape, two detection coils cannot be arranged on the same circumference of one wiring layer. Therefore, it is necessary to form two detection coils on different wiring layers, or to make two detection coils on the same wiring layer with different radial positions (distances from the axis of rotation). However, the distance between the two detection coils formed on different wiring layers and the conductor target is different. In addition, since the conductor target is formed in a fan shape with the axis of rotation as the center, the width in the circumferential direction is different depending on the radial position. Therefore, in the two detection coils with different radial positions, that is, the inner diameter side detection coil and the outer diameter side detection coil, the area of ​​the portion substantially opposite to the conductor target is different. Therefore, in any case, the output of the detection coil is prone to imbalance, requiring special signal processing.

[0015] In addition, in Patent Document 4 Figure 2 In the case of a structure, it is necessary to design a balanced offset so that positive and negative are detected on the outside and inside of the circle even in the same phase. Therefore, it is difficult to design the pattern shape in order to obtain the necessary accuracy.

[0016] On the other hand, when a position detector is used for controlling a motor, the rotor of the position detector is generally mounted on the opposite output shaft side of the motor shaft. When the motor is assembled in a device utilizing its driving force, a radial load is sometimes applied to the motor shaft. As a result, the motor shaft is sometimes bent and the axis center on the opposite output shaft side is offset. As shown in Patent Documents 2 and 3, when only a portion of the circumference around the rotation axis is detected, the offset of the axis center becomes an offset of the detection position, which has an adverse effect on the motor control.

[0017] One embodiment of the present invention provides an inductive position detector that can solve at least one of the above-mentioned technical problems.

[0018] More specifically, one embodiment of the present invention provides an inductive position detector that has a high degree of design freedom, is compact, and has a high detection resolution. Technical means for solving technical problems

[0019] One embodiment of the present invention provides an inductive position detector having the following features.

[0020] 1. An inductive position detector comprising: a stator having a wiring substrate; a rotor having a non-conductive member disposed opposite to the stator and rotating relative to the stator around a predetermined rotation axis; a plurality of conductor targets having the same shape and size, periodically arranged along a circumference around the rotation axis and held on the non-conductor component of the rotor, and moving along a rotation track around the rotation axis as the rotor rotates; and A plurality of chip inductors are arranged to be opposite to the rotating track at different spatial phases relative to the plurality of conductor targets, and are surface-mounted on the main surface of the wiring substrate of the stator, each constituting a plurality of detection coils for detecting changes in the magnetic field accompanying the passage of the conductor target.

[0021] When the rotor rotates around the rotation axis, multiple conductor targets maintained on the non-conductive part of the rotor (typically an insulator part, such as an insulating substrate) move through a rotating track around the rotation axis. On the main surface (mounting surface) of the stator's wiring substrate, chip inductors that respectively constitute multiple detection coils are arranged in a manner opposite to the rotating track of the conductor target. The chip inductor detects the change in the magnetic field accompanying the passage of the conductor target. That is, a signal representing the change in the magnetic field is output. Since the spatial phases of the multiple chip inductors relative to the multiple conductor targets are different, signals of different phases are output as the rotor rotates. Therefore, by processing the output signals of the multiple chip inductors, the relative rotational position of the rotor relative to the stator can be detected.

[0022] Chip inductors are small electrical components that can increase the number of turns and are available on the market at a low price. Therefore, when the number of conductor targets is increased to increase the number of poles and improve the detection resolution, a configuration corresponding to a smaller conductor target period (the spacing between conductor targets) can be performed, and the detection signal will not become too small and does not require excessive costs. In addition, the performance uniformity of chip inductors produced in industrial batches is high. Therefore, a uniform detection signal can be obtained from multiple chip inductors, thereby eliminating the need for complex signal processing.

[0023] In addition, unlike a structure in which multiple detection coils are formed on a silicon substrate through a semiconductor manufacturing process, multiple chip inductors as independent components can be arranged at any position relative to the rotating track, so the configuration has a higher degree of freedom. Therefore, it is also possible to distribute them around the entire circumference of the rotating track. Such a full-circle configuration is a configuration that is easy to deal with the axial deviation of the rotating shaft combined with the rotor. Since the chip inductor is small, even if the design shortens the conductor target period to improve the resolution, it can be configured throughout the circumference.

[0024] In this way, it is possible to provide an inductive position detector that has a high degree of design freedom, is compact, and has a high detection resolution.

[0025] Typically, the plurality of conductor targets are equal to each other along the length of the rotating track, for example, a plurality of conductor targets of the same shape and size are arranged rotationally symmetrically around the rotation axis.

[0026] The plurality of chip inductors can be mounted on one main surface, that is, the same main surface, of a wiring substrate of the stator. Thus, the distances from the plurality of chip inductors to the conductor target can be made uniform, thereby making the outputs from the plurality of chip inductors uniform. Typically, the plurality of chip inductors are mounted on the main surface opposite to the rotor on the upper surface of the wiring substrate. Thus, since the chip inductor can be brought close to the conductor target, the output variation of the chip inductor can be increased as the conductor target passes. However, the plurality of chip inductors can also be mounted on the main surface of the wiring substrate on the opposite side to the rotor. Even in this case, although the wiring substrate is sandwiched, the distances from the plurality of chip inductors to the conductor target become approximately equal.

[0027] In addition, a plurality of chip inductors may be mounted on the upper surface of one principal surface of the wiring substrate, and a plurality of chip inductors may be mounted on the upper surface of another principal surface of the wiring substrate. By mounting chip inductors on both surfaces of the wiring substrate, the number of chip inductors can be increased, for example, twice the number of chip inductors can be mounted. The greater the number of chip inductors, the greater the number of turns overall, and thus the output can be increased. In addition, the greater the number of chip inductors, the more average the deviation between the chip inductors, and thus the detection accuracy can be improved. On one principal surface and the other principal surface of the wiring substrate, since the distances from the plurality of chip inductors to the conductor target are equal, the outputs of the plurality of chip inductors arranged on each principal surface can be made uniform, without the need for complex signal processing.

[0028] 2. The inductive position detector according to item 1, wherein the conductor targets are arranged along the rotation track at a predetermined conductor target period. The chip inductor has a coil width along the rotating track that is 25% to 75% of a period of the conductor target.

[0029] In this structure, the coil width along the rotating track of the chip inductor is 25% to 75% (25% to 75%) of the conductor target period. As a result, the chip inductor can output a good detection signal that changes as the conductor target passes. By using small chip inductors produced industrially and increasing the number of conductor targets to improve the detection resolution, even if the conductor target period is shortened accordingly, a position detector for detecting the rotation position using a chip inductor with a coil width of 25% to 75% of the conductor target period can be constructed. The coil width of the chip inductor is preferably approximately 50% of the conductor target period, but as long as it is within the range of 25% to 75%, good detection can be performed. Therefore, it is easy to select a suitable chip inductor from the standardized chip inductors provided to the market. When the coil width of the chip inductor is 50% of the conductor target period, it may not be an ideal condition. The optimal design conditions depend on factors such as the axial angle, size, and rotor / stator gap of the position detector.

[0030] 3. The inductive position detector according to item 1 or 2, wherein the conductor targets are arranged along the rotation track at a predetermined conductor target period. The multiple chip inductors constitute a first phase group, a second phase group, a third phase group and a fourth phase group, and the first phase group, the second phase group, the third phase group and the fourth phase group respectively include at least one first phase chip inductor, at least one second phase chip inductor, at least one third phase chip inductor and at least one fourth phase chip inductor configured with a phase difference of every quarter cycle relative to the conductor target period.

[0031] Since the spatial phases of the first-phase chip inductor, the second-phase chip inductor, the third-phase chip inductor and the fourth-phase chip inductor relative to the conductor target differ by 90 degrees, detection signals for accurately detecting the rotational position of the rotor can be obtained from them.

[0032] A plurality of chip inductors may be arranged at equal intervals or unequal intervals along the rotating track. In addition, a plurality of chip inductors may be arranged over the entire circumference of the rotating track, or there may be regions where chip inductors are arranged and regions where chip inductors are not arranged along the rotating track.

[0033] 4. An inductive position detector as described in any one of items 1 to 3, wherein 4N (N is a natural number) of the chip inductors are arranged at equal intervals throughout the entire circumference of the rotating track and along the rotating track, The number Y (Y is a natural number) of the conductor targets is represented by Y=4NM±N (M is a natural number).

[0034] According to this structure, 4N chip inductors are arranged at equal intervals on the entire circumference of the circular track. On the other hand, the number Y of conductor targets arranged at equal intervals along the circular track satisfies Y=4NM±N. Therefore, the 4N chip inductors can be classified into 4 groups (each group is composed of N chip inductors) each differing by 90 degrees in spatial phase relative to the conductor target. That is, a first phase group including N first-phase chip inductors, a second phase group including N second-phase chip inductors, a third phase group including N third-phase chip inductors, and a fourth phase group including N fourth-phase chip inductors. Therefore, detection signals with a phase difference of 90 degrees can be obtained from the first phase group, the second phase group, the third phase group, and the fourth phase group.

[0035] 5. An inductive position detector as described in any one of items 1 to 4, wherein a first rotating track is used as a first group of the plurality of conductor targets and the plurality of chip inductors of the rotating track, and a second rotating track different from the first rotating track is used as a second group of the plurality of conductor targets and the plurality of chip inductors of the rotating track, and the stator and the rotor are used to share the same arrangement, The number Y of the plurality of conductor targets in the first group 1 (Y 1 is a natural number) and the number Y of the plurality of conductor targets of the second group 2 (Y 2 are natural numbers) are different from each other.

[0036] According to this structure, an inductive position detector having a multi-track structure including a first rotating track and a second rotating track can be formed. 1 and the number Y of the second group of conductor targets corresponding to the second rotation track 2 Differently, the rotational position in a wider rotational angle range can be detected distinguishably.

[0037] 6. The inductive position detector according to item 5, wherein the number Y of the plurality of conductor targets in the first group is 1 and the number Y of the plurality of conductor targets of the second group 2 Mutually prime.

[0038] According to this configuration, the rotational position can be detected in a wider rotation angle range. More specifically, the absolute detection of the rotational position in the range of one rotation (360 degrees) can be performed.

[0039] 7. An inductive position detector as described in item 5 or 6, which also includes an excitation coil, which is arranged on the wiring substrate of the stator and is used to induce voltage in the multiple chip inductors of the first group and the multiple chip inductors of the second group and are shared.

[0040] According to this configuration, since a common exciting coil can be used for exciting the first and second groups of chip inductors, the configuration can be simplified.

[0041] 8. An inductive position detector as described in Item 7, wherein the excitation coil includes: a first excitation coil, which is in a ring shape and, when observed along the rotation axis, encloses the multiple chip inductors of the first group and the multiple chip inductors of the second group; and a second excitation coil, which is in a ring shape and, when observed along the rotation axis, is arranged around the rotation axis in a manner of being enclosed by the multiple chip inductors of the first group and the multiple chip inductors of the second group.

[0042] According to this configuration, the first group and the second group of chip inductors can be sufficiently excited by the two inner and outer excitation coils, so a large detection signal can be obtained.

[0043] 9. The inductive position detector according to any one of items 1 to 8, wherein each conductor target includes a conductor solid pattern or an annular coil conductor pattern formed on the non-conductor component, and the plurality of conductor targets are insulated from each other.

[0044] Typically, the lengths of the plurality of conductor targets along the rotating track are equal to each other, for example, the plurality of conductor targets of the same shape and size are arranged rotationally symmetrically around the rotation axis. More typically, there is a gap between the adjacent conductor targets along the rotating track. The gap may also be equal to the length of the conductor target along the rotating track.

[0045] 10. The inductive position detector according to any one of items 1 to 8, wherein the plurality of conductor targets are connected to each other to form a ring-shaped coil conductor pattern extending over the entire circumference.

[0046] Thus, in some embodiments, a plurality of independent conductor targets arranged at equal intervals along the circumference around the rotation axis are held in the non-conductor part of the rotor to form a conductor pattern having periodicity (geometric periodicity). Then, in another embodiment, a conductor pattern having periodicity (geometric periodicity) is formed in such a manner that a plurality of conductor targets connected to each other are formed along the circumference around the rotation axis over the entire circumference of the ring-shaped coil conductor pattern.

[0047] Therefore, the conductor target refers to a conductor of one period of a conductor pattern having periodicity (geometric periodicity) formed along a circumference around the rotation axis. The conductor is an independent conductor pattern in some embodiments and is a part of a continuous conductor pattern in other embodiments.

[0048] 11. The inductive position detector according to any one of items 1 to 10, wherein the chip inductor is a stacked chip inductor having a pair of connection electrodes at both ends.

[0049] By using stacked chip inductors, a small detection coil with a large number of turns can be constructed. Therefore, in order to increase the number of conductor targets to improve the detection resolution, even if the conductor target period becomes shorter and the size of the chip inductor is correspondingly limited, a detection signal of the required size can be obtained from the chip inductor. In addition, it is also easy to realize a design in which multiple chip inductors are arranged on the entire circumference of the rotating track.

[0050] 12. The inductive position detector as described in any one of items 1 to 11 further includes an excitation coil, which is arranged on the wiring substrate of the stator and is formed into a ring shape that encloses the multiple chip inductors when observed along the rotation axis, and generates a magnetic field for inducing voltage in the multiple chip inductors.

[0051] According to this structure, by applying an AC voltage to the excitation coil, an AC voltage can be induced in the chip inductor. In this state, when the conductor target passes near the chip inductor, the eddy current induced in the conductor target by the magnetic field from the excitation coil cancels the magnetic field of the excitation coil. As a result, the voltage induced in the chip inductor changes. In this way, the chip inductor outputs a detection signal that changes according to the passage of the conductor target.

[0052] 13. An inductive position detector as described in any one of items 1 to 12, wherein the plurality of chip inductors are connected in a manner to form an AC bridge circuit having a pair of AC voltage application terminals and a pair of signal detection terminals.

[0053] In this structure, when an AC voltage is applied to the AC voltage application end of the AC bridge circuit that bridges the chip inductor, a detection signal indicating the impedance change of the chip inductor appears at the signal detection end of the AC bridge circuit. Since most of the impedance of the chip inductor is inductance, the detection signal of the AC bridge circuit can be regarded as a signal indicating the change in the inductance of the chip inductor. On the other hand, since the inductance of the chip inductor changes depending on the positional relationship with the conductor target, the change in inductance can be detected based on the detection signal from the AC bridge circuit, thereby detecting the position of the conductor target. That is, the rotational position of the rotor that holds the conductor target with a non-conductive component can be detected.

[0054] The above and other objects, features and effects of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1It is an exploded perspective view for explaining the structure of the inductive position detector according to the first embodiment of the present invention. Figure 2 yes Figure 1 Side view of an inductive position detector. Figure 3 It is a plan view showing the relative arrangement of the conductor target of the rotor and the chip inductor arranged on the stator. Figure 4 is a circuit diagram showing an equivalent circuit of a stator. Figure 5A , Figure 5B and Figure 5C 1 is a waveform diagram showing an example of an AC voltage generated by an excitation source and a detection signal that is 90 degrees out of phase. Figure 6 It is an exploded perspective view of an inductive position detector according to Embodiment 2 of the present invention. Figure 7 It is a plan view showing the relative arrangement of the conductor target of the rotor and the chip inductor arranged on the stator. Figure 8 is a circuit diagram showing an equivalent circuit of a stator. Fig. 9 It is an exploded perspective view showing the structure of an inductive position detector according to Embodiment 3 of the present invention. Fig.10 Yes means Fig. 9 Circuit diagram of the equivalent circuit of the stator of the inductive type position detector. Fig.11 It is an exploded perspective view for explaining the structure of an inductive position detector according to Embodiment 4 of the present invention. Fig.12 It is a plan view showing the positional relationship between the conductor target of the rotor and the chip inductor arranged on the stator. Fig.13 is a circuit diagram showing an equivalent circuit of a stator. Fig.14A It is a plan view showing a structural example including a conductor target formed of a coil-shaped conductor pattern. Fig. 14B It is a plan view showing another structural example including a conductor target formed of a coil-shaped conductor pattern. Figures 15A to 15E Shows examples of various conductor targets. Figures 16A to 16D An example of dividing the conductor target in the annular coil conductor pattern which is continuous throughout the entire circumference is shown. DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0057] Figure 1 It is an exploded perspective view for explaining the structure of the inductive position detector 100 according to the first embodiment of the present invention. Figure 2 is along Figure 1 A side view of the inductive position detector 100 as viewed from the direction of arrow 101 .

[0058] The inductive position detector 100 includes a stator 1 and a rotor 2 that rotates relative to the stator 1 around a rotation axis 3a, and is configured to output a detection signal indicating the relative rotation position of the rotor 2 relative to the stator 1 around the rotation axis 3a. The rotor 2 is connected to a rotating shaft 3 (refer to Figure 2 ) is coupled to the rotating shaft 3 and rotates around the rotating axis 3a together with the rotating shaft 3. The stator 1 has a printed circuit board 10 (printed wiring board) as a wiring board. The rotor 2 is composed of another printed circuit board 20 arranged at a predetermined interval 4 (for example, 0.1 mm to 1 mm) relative to the printed circuit board 10.

[0059] The printed circuit board 10 of the stator 1 includes an insulating substrate 11 and a conductor pattern (e.g., a copper foil pattern) formed on at least one of the main surfaces 10a and 10b. The printed circuit board 10 may be a multilayer printed circuit board having a plurality of stacked wiring layers (e.g., four wiring layers), and in this case, the wiring layers not exposed on the main surfaces 10a and 10b may have a conductor pattern.

[0060] Similarly, the printed circuit board 20 of the rotor 2 has an insulating substrate 21 as a non-conductive component, and a plurality of conductor targets T formed of a conductor pattern (e.g., a copper foil pattern) formed on one of the main surfaces 20a, 20b and thus held on the insulating substrate 21. In this embodiment, the conductor target T is formed on the main surface 20a on the opposite side to the stator 1, but it can also be formed on the other main surface 20b opposite to the stator 1. In addition, when the printed circuit board 20 is composed of a multilayer printed circuit board, the conductor target T can also be formed on the internal wiring layer other than the main surfaces 20a, 20b. The conductor target T is preferably formed on the same wiring layer (including the main surface) of the printed circuit board 20. In order to shorten the distance from the chip inductors L1, L2, L3, and L4 described later, the conductor target T is preferably formed on the wiring layer (e.g., the main surface 20b) as close to the stator 1 as possible.

[0061] exist Figure 1 and Figure 2 In the figure, for the sake of clarity, the conductor target T is marked with oblique lines. The same is true in other drawings described later.

[0062] Figure 3It is a plan view obtained by seeing through the insulating substrate 21 and observing along the rotation axis 3 a , and shows the relative arrangement between the conductive target T and the chip inductors L1 , L2 , L3 , and L4 (hereinafter collectively referred to as “chip inductors L”) arranged on the stator 1 .

[0063] The conductor targets T are periodically arranged along the circumference around the rotation axis 3a and are held on one main surface of the insulating substrate 21. Thus, the plurality of conductor targets T constitute a conductor pattern having geometric periodicity along the circumferential direction around the rotation axis 3a. The conductor of one period of the conductor pattern is one conductor target T. The plurality of conductor targets T move along a rotation track O (circular track) around the rotation axis 3a as the rotation shaft 3 rotates and then as the rotor 2 rotates.

[0064] In this embodiment, a plurality of conductor targets T are arranged at equal intervals with a predetermined period (pitch) λ (hereinafter referred to as "conductor target period λ") on the entire circumference around the rotation axis 3a. In this embodiment, each conductor target T is a conductor solid pattern formed on one main surface of the insulating substrate 21, and the plurality of conductor targets T are separated and insulated from each other in the circumferential direction. That is, each conductor target T is composed of an independent conductor pattern (conductor basic pattern). The lengths (widths) of the plurality of conductor targets T along the rotation track O are equal to each other. More specifically, in this embodiment, the plurality of conductor targets T are composed of conductor patterns of the same shape and size, and are arranged rotationally symmetrically around the rotation axis 3a. More specifically, each conductor target T is configured as a sector centered on the rotation axis 3a (more precisely, a sector obtained by cutting off the inner diameter portion). In the illustrated example, the interval between adjacent conductor targets T along the rotation track O, that is, the length of the rotation track O along the non-conductor portion 23 is equal to the length (width) of the rotation track O along the conductor target T, but this is an example. The length (width) of the conductor target T along the rotating track O depends on the design of the inductive position detector 100. For example, about 70% of the conductor target period λ may be optimal.

[0065] A plurality of chip inductors L are surface mounted on a main surface 10a of a printed substrate 10 constituting the stator 1. In this embodiment, the plurality of chip inductors L are mounted on the main surface 10a opposite to the rotor 2, but may be mounted on other main surfaces 10b on the opposite side to the rotor 2. The plurality of chip inductors L are arranged so as to have different spatial phases relative to the plurality of conductor targets T and to be opposite to the rotation orbit O of the conductor target T. Thus, the plurality of chip inductors L respectively constitute a plurality of detection coils for detecting changes in the magnetic field accompanying the passage of the conductor target T. The plurality of chip inductors L are surface mounted on the same main surface 10a of the printed substrate 10, and therefore, the intervals from the rotor 2 (more specifically, the intervals from the conductor target T) are substantially equal.

[0066] Multiple chip inductors L are typically of the same specifications for industrial mass production. Each chip inductor L has a coil width W of 25% to 75% (25% to 75%) of the conductor target period λ along the rotating track O. The coil width W is preferably approximately 50% of the conductor target period λ, but good detection can be performed as long as it is within the range of 25% to 75%. Therefore, a chip inductor having a coil width in the range of 25% to 75% of the conductor target period λ can be selected from the standardized chip inductors provided to the market.

[0067] For the chip inductor L, a pair of connecting electrodes 31 and 32 at both ends can be used (see Figure 1 ) of a stacked chip inductor. Examples of stacked chip inductors are described, for example, in Patent Document 5. By using stacked chip inductors, a small detection coil with a large number of turns can be constructed. Thus, in order to increase the conductor target T and improve the detection resolution, even if the conductor target period λ becomes shorter, a detection signal of the required size can be obtained from the chip inductor L.

[0068] The chip inductor L typically has a rectangular parallelepiped shape with the direction in which the connection electrodes 31 and 32 are opposite to each other being the long side direction. Then, when the coil center axis direction (the direction of the center axis of the winding) is set perpendicular to the main surface 10a of the printed substrate 10 and the surface is mounted on the printed substrate 10, the length of the short side direction is substantially equal to the coil width W of the built-in coil. In this embodiment, the chip inductor L is mounted on the printed substrate 10, and its long side direction is consistent with the radial direction of the rotating track O, but its long side direction does not need to be consistent with the radial direction of the rotating track O.

[0069] In this embodiment, a plurality of chip inductors L are arranged at equal intervals along the rotating track O around the entire circumference of the rotating axis 3a. In this embodiment, four chip inductors L are arranged at 90-degree angle intervals on the circumference around the rotating axis 3a. These chip inductors L are the first-phase chip inductor L1 (first phase group), the second-phase chip inductor L2 (second phase group), the third-phase chip inductor L3 (third phase group), and the fourth-phase chip inductor L4 (fourth phase group) arranged with a phase difference of one-quarter period relative to the conductor target period λ.

[0070] In this embodiment, five conductor targets T are arranged on a circle around the rotation axis 3a with a conductor target period λ of 72 degrees, which corresponds to one period of electrical angle, i.e., 360 degrees. Since four chip inductors L are arranged with a period p (pitch) of 90 degrees (hereinafter referred to as "chip inductor period p"), ​​the difference between the conductor target period λ and the chip inductor period p is 18 (=90-72) degrees. 18 (=72 / 4) degrees corresponds to one quarter of the conductor target period λ (72 degrees).

[0071] Therefore, the two chip inductors L that are in a 90-degree positional relationship in the mechanical angle have a phase difference of 90 degrees in the electrical angle, that is, one-fourth of the conductor target period λ. Specifically, the second-phase chip inductor L2 has a phase difference of 90 degrees relative to the first-phase chip inductor L1. Similarly, the third-phase chip inductor L3 has a phase difference of 90 degrees relative to the second-phase chip inductor L2, and the fourth-phase chip inductor L4 has a phase difference of 90 degrees relative to the third-phase chip inductor L3. Therefore, the third-phase chip inductor L3 has a phase difference of 180 degrees relative to the first-phase chip inductor L1, and they are in opposite phases to each other. Similarly, the fourth-phase chip inductor L4 has a phase difference of 180 degrees relative to the second-phase chip inductor L2, and they are in opposite phases to each other.

[0072] Each chip inductor L sets the coil center axis direction parallel to the rotation axis 3a and is surface mounted on the printed circuit board 10. Therefore, when the magnetic field in the coil center axis direction, i.e., the direction parallel to the rotation axis 3a, changes, the chip inductor L generates an induced voltage corresponding to the change in the magnetic field.

[0073] The excitation coil 12 is provided on the printed circuit board 10 constituting the stator 1. In the top view (see Figure 2 ), the excitation coil 12 is formed into a ring shape with multiple chip inductors L facing inward. That is, the coil center axis direction of the excitation coil 12 is parallel to the rotation axis 3a. In this embodiment, the excitation coil 12 is formed into a ring shape with multiple conductor targets T facing inward in this top view. In this embodiment, in this top view, the excitation coil 12 is roughly annular. Specifically, the excitation coil 12 is a pattern coil composed of a spiral conductor pattern formed on the printed substrate 10, and is formed into a ring shape as a whole (a circular ring shape in this embodiment). The printed substrate 10 may be, for example, a stacked printed substrate in which multiple wiring layers are stacked. In this case, pattern coils may also be formed with spiral conductor patterns on multiple wiring layers (for example, 4 layers), and these pattern coils may be connected by connecting through holes between the wiring layers to serve as the excitation coil 12.

[0074] An excitation source 5 that generates an AC voltage is connected to the lead-out portions 12a and 12b of the excitation coil 12. When an AC voltage is applied from the excitation source 5 to the excitation coil 12, the excitation coil 12 generates a high-frequency magnetic field that reverses in direction at the frequency of the AC voltage in a direction parallel to the rotation axis 3a. The high-frequency magnetic field generates an induced electromotive force in the chip inductor L because the magnetic field of the excitation coil 12 interlinks with the chip inductor L.

[0075] Although not shown in the figure, a conductor pattern (more specifically, a copper foil pattern) for connecting the chip inductor L to form a detection circuit is formed on the printed circuit board 10 of the stator 1 .

[0076] Figure 4 Represents the equivalent circuit of stator 1. The first-phase chip inductor L1 generates an A-phase detection signal, and the third-phase chip inductor L3 generates an / A-phase detection signal of the opposite phase. Therefore, an A-phase detection circuit 6 is formed, and the A-phase detection circuit 6 is connected (differentially connected) to the same polarity ends of the first-phase chip inductor L1 and the third-phase chip inductor L3, and these differential signals are output as detection signals VA. The second-phase chip inductor L2 generates a B-phase detection signal with a phase difference of 90 degrees for the A-phase detection signal. Then, the fourth-phase chip inductor L4 generates a / B-phase detection signal of the opposite phase of the B-phase detection signal. Therefore, a B-phase detection circuit 7 is formed, and the B-phase detection circuit 7 is connected (differentially connected) to the same polarity ends of the second-phase chip inductor L2 and the fourth-phase chip inductor L4, and these differential signals are output as detection signals VB.

[0077] As described above, when an AC voltage (Asinωt, where A is a constant representing the amplitude, ω represents the angular frequency, and t represents the time) is applied from the excitation source 5 to the excitation coil 12, detection signals VA and VB are generated from the A-phase detection circuit 6 and the B-phase detection circuit 7, respectively, according to the changes in the cross-linkage magnetic flux between the high-frequency magnetic field generated by the excitation coil 12 and the chip inductor L. The high-frequency magnetic field generated by the excitation coil 12 induces eddy currents on the conductor target T. The eddy currents generate a magnetic field in the opposite direction to the magnetic field generated by the excitation coil 12. Therefore, when the conductor target T is opposite to the chip inductor L, the voltage induced in the chip inductor L is reduced. By utilizing this phenomenon, the detection signals VA and VB are appropriately processed by the signal processing circuit 8, and the rotational position information can be obtained.

[0078] For the voltage induced in the chip inductor L, the fixed part is C and the variable part is V. The phase is positive when the conductor target T moves in the clockwise direction CW, and Figure 3 The chip inductor L1 is used as the reference. Then, the voltage V induced in each chip inductor L1, L2, L3, and L4 at the rotation angle θ is L1 、V L2 、V L3 、V L4 As follows: Wherein, K represents the amplitude of the induced AC voltage. V L1 =Ksinωt·{C+V·sin(θ+0)}=Ksinωt·(C+V·sinθ)…(1) V L2 =Ksinωt·{C+V·sin(θ+90)}=Ksinωt·(C+V·cosθ)…(2) V L3=Ksinωt·{C+V·sin(θ+180)}=Ksinωt·(CV·sinθ)…(3) V L4 =Ksinωt·{C+V·sin(θ+270)}=Ksinωt·(CV·cosθ)…(4)

[0079] Since the chip inductors L1 and L3 and the chip inductors L2 and L4 are respectively connected differentially, the detection signals VA and VB are as follows. VA=V L1 -V L3 =Ksinωt·(C+V·sinθ)-Ksinωt·(CV·sinθ) =2V·Ksinωt·sinθ…(5) VB=V L2 -V L4 =Ksinωt(C+V·cosθ)-Ksinωt(CV·cosθ) =2V·Ksinωt·cosθ…(6)

[0080] Figure 5A An example of the waveform of the AC voltage generated by the excitation source 5 is shown, Figure 5B and Figure 5C An example of the waveform of the detection signals VA and VB is shown in FIG. In this way, the detection signals VA and VB output by the detection circuits 6 and 7 become signals obtained by amplitude modulating the high-frequency signal based on the change of the induced voltage generated by the rotation of the rotor 2. Since the chip inductors L1 and L3 constituting the A-phase detection circuit 6 and the chip inductors L2 and L4 constituting the B-phase detection circuit 7 are arranged on the stator 1 at intervals of 90 degrees, the detection signals VA and VB become signals with a phase difference of 90 degrees from each other. Therefore, by demodulating the detection signals VA and VB with the signal processing circuit 8 and performing inverse tangent calculations, the rotation angle θ of the rotor 2 can be calculated.

[0081] Figure 6 2 is an exploded perspective view of an inductive position detector 200 according to Embodiment 2 of the present invention. Figure 7 3a is a top view of the inductive position detector 200 viewed along the rotation axis 3a, showing the arrangement relationship between the conductor target T and the chip inductor L by seeing through the insulating substrate 21 of the rotor 2. Figure 8 is an equivalent circuit diagram showing the electrical structure of the stator 1. In these drawings, the above Figure 1 to Figure 4 Corresponding parts of the parts shown are indicated by the same reference numerals.

[0082] In this embodiment, the number of conductor targets T and the number of chip inductors L are each doubled compared to Embodiment 1. In other words, the conductor target period λ (36 degrees) and the chip inductor period p (45 degrees) are each half of that in Embodiment 1. When the spatial phase relative to the conductor target T is studied, it is found that the phases of the chip inductors L spaced 180 degrees apart around the rotation axis 3a are equal. That is, the plurality of chip inductors L can be classified into: a first phase group G1 (A phase) consisting of a pair of first phase chip inductors L1 (1) and L1 (2) opposite to each other with the rotation axis 3a sandwiched therebetween; a second phase group G2 (B phase) consisting of another pair of second phase chip inductors L2 (1) and L2 (2) opposite to each other with the rotation axis 3a sandwiched therebetween; a third phase group G3 ( / A phase) consisting of another pair of third phase chip inductors L3 (1) and L3 (2) opposite to each other with the rotation axis 3a sandwiched therebetween; and a fourth phase group G4 ( / B phase) consisting of another pair of fourth phase chip inductors L4 (1) and L4 (2) opposite to each other with the rotation axis 3a sandwiched therebetween. Then, the spatial phases of the first phase chip inductor L1(1), L1(2), the second phase chip inductor L2(1), L2(2), the third phase chip inductor L3(1), L3(2) and the fourth phase chip inductor L4(1), L4(2) around the rotation axis 3a are each offset by one quarter of the conductor target period λ.

[0083] Therefore, a pair of first-phase chip inductors L1(1), L1(2) and a pair of third-phase chip inductors L3(1), L3(2) are connected in series and differentially to form an A-phase detection circuit 6, and a pair of second-phase chip inductors L2(1), L2(2) and a pair of fourth-phase chip inductors L4(1), L4(2) are connected in series and differentially to form a B-phase detection circuit 7. The A-phase detection circuit 6 and the B-phase detection circuit 7 are the same as those in the first embodiment, and output amplitude-modulated detection signals VA and VB with a phase shift of 90 degrees. However, since the conductor target period λ equivalent to 360 degrees in electrical angle is equivalent to 36 (=360 / 10) degrees in mechanical angle, the rotation position can be detected with twice the resolution compared to the first embodiment.

[0084] Although not shown in the figure, a conductor pattern (more specifically, a copper foil pattern) for connecting the chip inductor L to form a detection circuit is formed on the printed circuit board 10 of the stator 1 .

[0085] For the voltage induced in the chip inductor L, the fixed part is C and the variable part is V. The phase is positive when the conductor target T moves in the clockwise direction CW, with the chip inductor L1(1) as the reference. Therefore, at the rotation angle θ, the voltage V induced in each chip inductor L1(1), L2(1), L3(1), L4(1), L1(2), L2(2), L3(2), L4(2) is L1(1)、V L2(1) 、V L3(1) 、V L4(1) 、V L1(2) 、V L2(2) 、V L3(2) 、V L4(2) As follows: Wherein, K represents the amplitude of the induced AC voltage. V L1(1) =Ksinωt·{C+V·sin(θ+0)}=Ksinωt·(C+V·sinθ)…(7) V L2(1) =Ksinωt·{C+V·sin(θ+90)}=Ksinωt·(C+V·cosθ)…(8) V L3(1) =Ksinωt·{C+V·sin(θ+180)}=Ksinωt·(CV·sinθ)…(9) V L4(1) =Ksinωt·{C+V·sin(θ+270)}=Ksinωt·(CV·cosθ)…(10) V L1(2) =Ksinωt·{C+V·sin(θ+0)}=Ksinωt·(C+V·sinθ)…(11) V L2(2) =Ksinωt·{C+V·sin(θ+90)}=Ksinωt·(C+V·cosθ)…(12) V L3(2) =Ksinωt·{C+V·sin(θ+180)}=Ksinωt·(CV·sinθ)…(13) V L4(2) =Ksinωt·{C+V·sin(θ+270)}=Ksinωt·(CV·cosθ)…(14)

[0086] The chip inductors L1(1), L1(2) and L3(1), L3(2) as well as the chip inductors L2(1), L2(2) and L4(1), L4(2) are respectively connected in series and differentially, so the detection signals VA and VB are as described below. VA=V L1(1) +V L1(2) -V L3(1) -V L3(2) =2Ksinωt·(C+V·sinθ)-2Ksinωt·(CV·sinθ) =4V·Ksinωt·sinθ…(15) VB=VL2(1) +V L2(2) -V L4(1) -V L4(2) =2Ksinωt(C+V·cosθ)-2Ksinωt(CV·cosθ) =4V·Ksinωt·cosθ…(16)

[0087] Thus, in the second embodiment, since the change of the detection signals VA and VB can be detected to a greater extent as the number of chip inductors L increases, the signal-to-noise ratio (S / N ratio) can be improved. In addition, the chip inductors L arranged at relative positions away from 180 degrees in the mechanical angle detect signals of the same phase. Thus, the influence of errors such as the eccentricity of the stator 1 relative to the rotating shaft 3 and the inclination of the rotor 2 relative to the stator plane on the detection signal can be reduced, thereby improving the detection accuracy.

[0088] When Y (Y is a natural number) conductor targets T are arranged on the rotor 2 and 4N (N is a natural number) chip inductors L are arranged at equal intervals on the stator 1, consider the configuration conditions of the chip inductors L for forming two detection circuits 6 and 7 for generating detection signals VA and VB with a phase difference of 90 degrees in electrical angle.

[0089] The relationship when the conductor target period λ and the chip inductor period p have a phase difference of λ / 4 (one quarter of the conductor target period λ) is as follows (17): wherein M is a natural number. p=λ(M±1 / 4)…(17)

[0090] The conductor target period λ and the chip inductor period p are expressed by the following equations (18) and (19), respectively, using the circumferential length Cl of the rotating track O through which the conductor target T passes. λ=Cl / Y…(18) p=Cl / 4N…(19)

[0091] If equations (18) and (19) are substituted into equation (7) and transformed, the equation (20) is obtained. Therefore, if there is a combination of natural numbers Y, N, and M that satisfies the relationship of equation (20), detection signals having a phase difference of 90 degrees in electrical angle can be detected from detection circuits 6 and 7. Y=4NM±N…(20)

[0092] Embodiment 1 corresponds to the case where N=1, M=1, and Y=5. Embodiment 2 corresponds to the case where N=2, M=1, and Y=10.

[0093] Thus, according to the first and second embodiments, two detection circuits 6 and 7 for generating two detection signals VA and VB having a phase difference of 90 degrees can be formed by using a plurality of chip inductors L. Then, based on these detection signals VA and VB, the rotation position of the rotor 2, that is, the rotation position (rotation angle) of the rotating shaft 3 can be detected.

[0094] The chip inductor L is a small electrical component that can increase the number of turns and can be supplied at a low price on the market. Therefore, when the number of conductor targets T is increased to increase the number of poles and improve the detection resolution, a configuration corresponding to a smaller conductor target period λ can be performed, and the detection signal will not become too small, and excessive costs are not required. In addition, by mounting a plurality of chip inductors L on a main surface 10a of the printed substrate 10 of the stator 1, that is, the same main surface, the distance to the conductor target T can be made uniform. Furthermore, the performance uniformity of the chip inductors L produced in industrial batches is relatively high. Therefore, a uniform detection signal can be obtained from a plurality of chip inductors L, thereby eliminating the need for complex signal processing.

[0095] In the first and second embodiments, since a plurality of chip inductors L are mounted on the upper surface of the main surface 10a of the printed substrate 10 opposite to the rotor 2, the insulating substrate 11 of the printed substrate 10 on the stator 1 side does not exist between the plurality of chip inductors L and the conductive target T. Thus, since the distance between the plurality of chip inductors L and the conductive target T is short, a signal having a large amplitude variation as the conductive target T passes is extracted from each chip inductor L.

[0096] In addition, unlike a structure in which a plurality of detection coils are formed on a silicon substrate by a semiconductor manufacturing process, a plurality of chip inductors L as independent elements can be arranged at any position relative to the rotating track, and therefore, the degree of freedom of arrangement is high. Therefore, as in embodiments 1 and 2, a configuration distributed over the entire circumference of the rotating track O is also possible. Such a full-circle configuration is a configuration that is easy to cope with the axial center deviation of the rotating shaft 3 coupled to the rotor 2. Specifically, in a case where the rotating shaft 3 is the end portion on the opposite output shaft side of the motor shaft of the motor, even if the axial center of the rotating shaft 3 is offset due to the radial load applied to the motor shaft, the offset of the detection position can be avoided by simple signal processing.

[0097] In particular, by using a stacked chip inductor as the chip inductor L, a structure in which the chip inductor L is small and has more coils can be formed. Therefore, even when the conductor target period λ is designed to be reduced to improve the resolution, the chip inductor L can be arranged along the entire circumference of the rotating track O.

[0098] In Embodiments 1 and 2, the conductor targets T are arranged at a predetermined conductor target period λ along the rotation track O. The chip inductor L has a coil width W along the rotation track O that is 25% to 75% (25% or more and 75% or less) of the conductor target period λ.

[0099] More specifically, in Embodiment 1, the coil width W of the chip inductor L is approximately 25% of the conductor target period λ. In addition, in Embodiment 2, the coil width W of the chip inductor L is approximately 50% of the conductor target period λ. If the number of conductor targets T on the rotor 2 is greater than that in Embodiment 2, the ratio of the coil width W of the chip inductor L to the conductor target period λ becomes larger, and if the ratio is approximately 75%, a signal of a waveform that can accurately detect the rotational position can be obtained. By using industrially produced small chip inductors L, even if the number of conductor targets T is increased to improve the detection resolution and the conductor target period λ is shortened accordingly, a small rotational position detector can be formed using a chip inductor L with a coil width W of 25% to 75% of the conductor target period λ.

[0100] In addition, if the coil width W of the chip inductor L is within the range of 25% to 75% of the conductor target period λ, good detection can be performed. Therefore, it is easy to select an appropriate chip inductor from standardized chip inductors provided to the market.

[0101] In embodiments 1 and 2, a plurality of chip inductors L arranged on the stator 1 constitute a first phase group, a second phase group, a third phase group, and a fourth phase group, and the first phase group, the second phase group, the third phase group, and the fourth phase group respectively include at least one first phase chip inductor L1, at least one second phase chip inductor L2, at least one third phase chip inductor L3, and at least one fourth phase chip inductor L4 arranged with a phase difference of one quarter of a period relative to the conductor target period λ. Since the first phase chip inductor L1 (chip inductor of the first phase group), the second phase chip inductor L2 (chip inductor of the second phase group), the third phase chip inductor L3 (chip inductor of the third phase group), and the fourth phase chip inductor L4 (chip inductor of the fourth phase group) differ in spatial phase by 90 degrees relative to the conductor target T, a detection signal for accurately detecting the rotation position of the rotor 2 can be obtained from them.

[0102] In particular, in embodiments 1 and 2, the first-phase chip inductor L1 and the third-phase chip inductor L3 having a spatial phase difference of 180 degrees are differentially connected to form a detection circuit 6. Similarly, the second-phase chip inductor L2 and the fourth-phase chip inductor L4 having a spatial phase difference of 180 degrees are differentially connected to form a detection circuit 7. Thus, detection signals VA and VB with a large amplitude and a phase difference of 90 degrees are obtained from the two detection circuits 6 and 7. Moreover, since the noise components that appear in common in multiple chip inductors L due to interference are removed by differential connection, the detection signals VA and VB accurately represent the position of the conductor target T. The so-called interference refers to the external magnetic field, the change in the distance between the stator 1 and the rotor 2 (manufacturing deviation), etc.

[0103] In the second embodiment, a plurality of first phase chip inductors L1, second phase chip inductors L2, third phase chip inductors L3 and fourth phase chip inductors L4 are provided, and the same phase chip inductors L are connected in series. This can obtain detection signals VA and VB with large amplitudes, and improve the S / N ratio.

[0104] As described above, by arranging Y conductor targets T and 4N chip inductors L that satisfy equation (20) at equal intervals around the entire circumference of the rotation axis 3a, the 4N chip inductors L can be classified into four phase groups (each phase group is composed of N chip inductors L) each having a spatial phase difference of 90 degrees relative to the conductor target T. That is, the first phase group G1 includes N first-phase chip inductors L1, the second phase group G2 includes N second-phase chip inductors L2, the third phase group G3 includes N third-phase chip inductors L3, and the fourth phase group G4 includes N fourth-phase chip inductors L4. Then, by differentially connecting the chip inductors L1 and L3 of the first phase group G1 and the third phase group G3, and differentially connecting the chip inductors L2 and L4 of the second phase group G2 and the fourth phase group G4, detection circuits 6 and 7 that output detection signals VA and VB that differ in phase by 90 degrees can be formed.

[0105] Fig. 9 : is an exploded perspective view showing the structure of an inductive position detector 300 according to Embodiment 3 of the present invention. Fig.10 : is a circuit diagram showing the equivalent circuit of the stator 1 side. Fig. 9 and Fig.10 In the figure, the corresponding parts of the various parts of the above-mentioned embodiment 2 are represented by the same figure marks.

[0106] This embodiment is different from the second embodiment in that the stator 1 does not include an exciting coil.

[0107] A plurality of chip inductors L are bridged to form an AC bridge circuit. More specifically, an A-phase AC bridge circuit 60 and a B-phase AC bridge circuit 70 are formed. That is, although not shown in the figure, a conductor pattern (more specifically, a copper foil pattern) for connecting the chip inductors L to form the A-phase AC bridge circuit 60 and the B-phase AC bridge circuit 70 is formed on the printed circuit board 10 of the stator 1.

[0108] The A-phase AC bridge circuit 60 is constructed by bridging the first-phase chip inductors L1(1), L1(2) and the third-phase chip inductors L3(1), L3(2) having a phase difference of 180 degrees relative to them. The first-phase chip inductors L1(1), L1(2) are respectively arranged on opposite sides of the A-phase AC bridge circuit 60, and the third-phase chip inductors L3(1), L3(2) are respectively arranged on the other opposite sides of the A-phase AC bridge circuit 60. The connection point between the first-phase chip inductor L1(1) and the third-phase chip inductor L3(2) is set as the first A-phase AC voltage application terminal 61, and the connection point between the third-phase chip inductor L3(1) and the first-phase chip inductor L1(2) is set as the second A-phase AC voltage application terminal 62. The midpoint between the first phase chip inductor L1(1) and the third phase chip inductor L3(1) is set as the first A phase signal detection terminal 63, and the midpoint between the third phase chip inductor L3(2) and the first phase chip inductor L1(2) is set as the second A phase signal detection terminal 64.

[0109] The B-phase AC bridge circuit 70 is constructed by bridging the second-phase chip inductors L2(1), L2(2) and the fourth-phase chip inductors L4(1), L4(2) having a phase difference of 180 degrees relative to them. The second-phase chip inductors L2(1), L2(2) are respectively arranged on opposite sides of the B-phase AC bridge circuit 70, and the fourth-phase chip inductors L4(1), L4(2) are respectively arranged on the other opposite sides of the B-phase AC bridge circuit 70. The connection point between the second-phase chip inductor L2(1) and the fourth-phase chip inductor L4(2) is set as the first B-phase AC voltage application terminal 71, and the connection point between the fourth-phase chip inductor L4(1) and the second-phase chip inductor L2(2) is set as the second B-phase AC voltage application terminal 72. The midpoint between the second-phase chip inductor L2(1) and the fourth-phase chip inductor L4(1) is set as the first B-phase signal detection terminal 73, and the midpoint between the fourth-phase chip inductor L4(2) and the second-phase chip inductor L2(2) is set as the second B-phase signal detection terminal 74.

[0110] An AC voltage is applied from the excitation source 5 to the A-phase AC bridge circuit 60 and the B-phase AC bridge circuit 70. The excitation source 5 includes a first excitation source 51 that generates a first AC voltage (Asinωt) and a second excitation source 52 that generates a second AC voltage (-Asinωt) that is inverted in phase with the first AC voltage. The first A-phase AC voltage application terminal 61 is connected to the first excitation source 51, and the first AC voltage (Asinωt) is applied. The second A-phase AC voltage application terminal 61 is connected to the second excitation source 52, and the second AC voltage (-Asinωt) is applied. The first B-phase AC voltage application terminal 71 is connected to the first excitation source 51, and the first AC voltage (Asinωt) is applied. The second B-phase AC voltage application terminal 72 is connected to the second excitation source 52, and the second AC voltage (-Asinωt) is applied. Then, the voltage appearing between the first A-phase signal detection terminal 63 and the second A-phase signal detection terminal 64 is detected as a detection signal VA. In addition, the voltage appearing between the first B-phase signal detection terminal 73 and the second B-phase signal detection terminal 74 is detected as a detection signal VB.

[0111] In this embodiment, AC voltage is applied to the A-phase AC bridge circuit 60 and the B-phase AC bridge circuit 70 from the common excitation source 5 , but an independent excitation source 5 may be used to apply AC voltage to the A-phase AC bridge circuit 60 and the B-phase AC bridge circuit 70 .

[0112] When the conductor target T faces the chip inductor L, the magnetic flux of the chip inductor L is blocked by the conductor target T, and the inductance of the chip inductor L is reduced. Taking advantage of this, in this embodiment, the rotation angle is detected based on the change in inductance of the chip inductor L caused by the rotation of the rotor 2 without using an excitation coil.

[0113] If the fixed part is set to LC and the variable part is set to LV, the change in inductance of the chip inductors L1(1), L2(1), L3(1), L4(1), L1(2), L2(2), L3(2), and L4(2) can be expressed as follows. L1(1): LC+LV·sin(θ+0)=LC+LV·sinθ…(21) L2(1): LC+LV·sin(θ+90)=LC+LV·cosθ…(22) L3(1): LC+LV·sin(θ+180)=LC-LV·sinθ…(23) L4(1): LC+LV·sin(θ+270)=LC-LV·cosθ…(24) L1(2): LC+LV·sin(θ+0)=LC+LV·sinθ…(25) L2(2): LC+LV·sin(θ+90)=LC+LV·cosθ…(26) L3(2): LC+LV·sin(θ+180)=LC-LV·sinθ…(27) L4(2): LC+LV·sin(θ+270)=LC-LV·cosθ…(28)

[0114] Therefore, the output signals from the A-phase AC bridge circuit 60 and the B-phase AC bridge circuit 70, namely, the detection signals VA and VB, are expressed as shown in equations (29) and (30), respectively, where k is a constant representing the amplitude. VA={L1(2) / (L1(2)+L3(2))-L3(1) / (L1(1)+L3(1))}·(2ksinωt-ksinωt) =LV / LC·ksinωt·sinθ…(29) VB={L2(2) / (L2(2)+L4(2))-L4(1) / (L2(1)+L4(1))}·(2ksinωt-ksinωt) =LV / LC·ksinωt·cosθ…(30) The AC bridge circuits 60 and 70 detect the change in the impedance of the chip inductor L caused by the change in the positional relationship with the conductor target T. The impedance of the chip inductor L includes a small DC resistance component in addition to the inductance component, but since the inductance component is dominant, the DC resistance component can be substantially ignored. Therefore, the change in the inductance of the chip inductor L caused by the change in the positional relationship with the conductor target T can be detected by the AC bridge circuits 60 and 70.

[0115] The detection signals VA and VB expressed by equations (29) and (30) are signals whose phases change by 90 degrees according to the rotation position of the conductor target T. By comparing equations (29) and (30) with the above equations (5) and (6), it can be seen that the detection signals VA and VB have the same phase as the rotation position of the conductor target T. Figure 5B and Figure 5C The waveforms shown are similar to each other. Therefore, the rotation position of the rotor 2 can be detected as in the first and second embodiments. Thus, a position detector capable of detecting the position of the rotor 2 can be constructed, although it is a structure without an exciting coil.

[0116] Fig.11 It is an exploded perspective view for explaining the structure of an inductive position detector 400 according to Embodiment 4 of the present invention. Fig.12This is a top view of the inductive position detector 400 viewed along the rotation axis 3a, and shows the positional relationship between the conductive target T and the chip inductor L by seeing through the insulating substrate 21 of the rotor 2. In these drawings, corresponding parts of the first and second embodiments are denoted by the same reference numerals.

[0117] The position detector 400 has a plurality of rotation orbits O around the rotation axis 3a. 1 , O 2 (Refer to Fig.12 ), with 1 , O 2 Specifically, the position detector 400 of this embodiment has a first rotation track O having a concentric circumference around the rotation axis 3a. 1 and the second rotation orbit O 2 The first rotating track O 1 Configured in the second rotation track O 2 The inner side of the second rotating track O is formed with a diameter smaller than that of the second rotating track O. 2 On one main surface 20a (in this embodiment, the main surface on the opposite side to the stator 1) of the printed circuit board 20 of the rotor 2, along the first rotation track O 1 A plurality of conductive targets T are arranged at equal intervals around the entire circumference. 1 , and along the second rotation track O 2 A plurality of conductive targets T are arranged at equal intervals around the entire circumference. 2 On one main surface 10a (in this embodiment, the main surface facing the rotor 2) of the printed circuit board 10 of the stator 1, along the first rotation track O 1 Multiple chip inductors L are arranged at equal intervals throughout the circumference. 1 , and along the second rotation track O 2 Multiple chip inductors L are arranged at equal intervals throughout the circumference. 2 .

[0118] Along the first rotation track O 1 Configured multiple chip inductors L 1 According to the relative conductor target T 1 The spatial phase around the rotation axis 3a is classified as follows: the first phase chip inductor L 1 1(1),L 1 1(2) is composed of the first phase group (phase A), the second phase chip inductor L 1 2(1),L 1 2(2) is composed of the second phase group (B phase), the third phase chip inductor L 1 3(1), L 13(2) constitutes the third phase group ( / A phase), and the fourth phase chip inductor L 1 4(1), L 1 4(2) forms the fourth phase group ( / B phase). Then, the first phase chip inductor L 1 1(1),L 1 1(2), second phase chip inductor L 1 2(1),L 1 2(2), the third phase chip inductor L 1 3(1), L 1 3(2) and the fourth phase chip inductor L 1 4(1), L 1 The spatial phase of 4(2) about the rotation axis 3a is shifted by one quarter of the conductor target period λ.

[0119] Similarly, along the second rotation track O 2 Configured multiple chip inductors L 2 According to the relative conductor target T 2 The spatial phase around the rotation axis 3a is classified as follows: the first phase chip inductor L 2 1(2),L 2 1(2),L 2 1(3) is composed of the first phase group (phase A), the second phase chip inductor L 2 2(2),L 2 2(2),L 2 2(3) is the second phase group (B phase), and the third phase chip inductor L 2 3(1), L 2 3(2), L 2 3(3) and the third phase group ( / A phase), and the fourth phase chip inductor L 2 4(1), L 2 4(2), L 2 4(3) forms the fourth phase group ( / B phase). Then, the first phase chip inductor L 2 1(1),L 2 1(2),L 2 1(3), second phase chip inductor L 2 2(1),L 2 2(2),L 2 2(3), the third phase chip inductor L 2 3(1), L 2 3(2), L 2 3(3) and the fourth phase chip inductor L 2 4(1), L 2 4(2), L 2The spatial phase of 4(3) about the rotation axis 3a is shifted by one quarter of the conductor target period λ.

[0120] Along the first rotation track O 1 Multiple conductor targets T configured 1 and multiple chip inductors L 1 The first group S 1 , they are opposite to each other. Similarly, along the second rotation track O 2 Multiple conductor targets T configured 2 and multiple chip inductors L 2 The second group S 2 , they are opposite to each other. The first group S 1 and the second group S 2 The rotor 2 and the stator 1 are shared.

[0121] The first group S 1 Multiple conductor targets T 1 The number of Y 1 With the second group S 2 Conductor target T 2 The number of Y 2 Different from each other. The first group S 1 Conductor target T 1 The number of Y 1 and chip inductor L 1 The number of 4N 1 The above equation (20) is satisfied, and therefore the following equation (31) is satisfied. Similarly, the second group S 2 Conductor target T 2 The number of Y 2 and chip inductor L 2 The number of 4N 2 The above formula (20) is satisfied, and therefore the following formula (32) is satisfied. Y 1 =4N 1 M 1 ±N 1 (Y 1 、N 1 、M 1 is a natural number)…(31) Y 2 =4N 2 M 2 ±N 2 (Y 2 、N 2 、M 2 is a natural number)…(32)

[0122] Fig.11 and Fig.12 The example shown is equivalent to Y 1 =14, N1 =2, M 1 =2, Y 2 =15, N 2 =3, M 2 =1.

[0123] The first group S 1 Multiple conductor targets T 1 The number of Y 1 With the second group S 2 Conductor target T 2 The number of Y 2 are different from each other, so that the rotation position in a wider rotation angle range can be distinguished and detected. In particular, if the first group S 1 Multiple conductor targets T 1 The number of Y 1 With the second group S 2 Conductor target T 2 The number of Y 2 If they are mutually prime, then one-rotation absolute detection can be performed to distinguishably detect the rotational positions within the range of one rotation (360 degrees).

[0124] In this example, the first group S 1 Multiple chip inductors L 1 And constitute the second group S 2 Multiple chip inductors L 2 All chip inductors of the same specification have the same shape and size in a plan view along the rotation axis 3 a .

[0125] In the example shown in the figure, each chip inductor L is arranged so that the long side direction is along the rotation radius direction around the rotation axis 3a. The long side direction of the chip inductor L is typically the direction in which the pair of connection electrodes 31 and 32 face each other. 1 Coil width W 1 and constitute the first group S 1 Multiple conductor targets T 1 The spacing (conductor target period λ 1 ) is about 25%. On the other hand, the chip inductor L 2 Coil width W 2 and constitute the second group S 2 Multiple conductor targets T 2 The spacing (conductor target period λ 2 ) is 50%. Of course, these are just examples, in the first group S 1 and the second group S 2 In the design, the conductor target T 1 、T 2 , so that the coil width W 1 , W2 Relative to the conductor target period λ 1 , 2 The ratio is 25% to 75%, and the chip inductor L is selected 1 , L 2 , just decide their configuration.

[0126] No need to add S in the first group 1 And the second group S 2 Use chip inductors of the same specification in the first group S 1 Multiple chip inductors L 1 Set the same specifications and set the second group S 2 Multiple chip inductors L 2 Set to different same specifications.

[0127] A common excitation coil 12 is provided on the printed circuit board 10 of the stator 1 for 1 Multiple chip inductors L 1 And the second group S 2 Multiple chip inductors L 2 In this embodiment, the excitation coil 12 includes a first excitation coil 121 and a second excitation coil 122. These are formed by a conductor pattern formed on the printed substrate 10. The first excitation coil 121 is configured to include a first group S in a top view observed along the rotation axis 3a. 1 Multiple chip inductors L 1 And the second group S 2 Multiple chip inductors L 2 On the other hand, the second excitation coil 122 is formed by the first group S in a plan view along the rotation axis 3a. 1 Multiple conductor targets T 1 And the second group S 2 Multiple conductor targets T 2 The first excitation coil 121 is arranged in a first group S and is formed in a ring shape (in the example shown in the figure, a circular ring shape) around the rotation axis 3a. 1 And the second group S 2 Multiple chip inductors L 1 , L 2 On the outer circumference side, the second excitation coil 122 is arranged on the inner circumference side thereof.

[0128] The first excitation coil 121 is formed into a ring shape by forming a spiral wiring pattern along the circumference around the rotation axis 3a. In the case where the printed substrate 10 is a laminated printed substrate in which a plurality of wiring layers are laminated, the spiral wiring patterns formed on the plurality of wiring layers may be connected by interlayer vias to form the first excitation coil 121. The same is true for the second excitation coil 122.

[0129] The first excitation coil 121 and the second excitation coil 122 are connected by a wiring pattern (not shown) in the printed circuit board 10 so that current flows in opposite circumferential directions around the rotation axis 3a in a top view along the rotation axis 3a. Therefore, when the first excitation coil 121 and the second excitation coil 122 are energized, the first excitation coil 121 and the second excitation coil 122 are in the area between them, that is, in the first group S 1 and the second group S 2 The configuration has multiple chip inductors L 1 , L 2 That is, the first excitation coil 121 and the second excitation coil 122 are configured to mutually enhance the magnetic field in the region therebetween.

[0130] Fig.13 : is a circuit diagram showing an equivalent circuit of the stator 1 .

[0131] Along the first rotation track O 1 The first group S configured 1 Multiple chip inductors L (inner side) 1 The connection is similar to that in the second embodiment. That is, a pair of first-phase chip inductors L 1 1(1),L 1 1(2) and a pair of third-phase chip inductors L 1 3(1), L 1 3(2) Series differential connection to form phase A detection circuit 6 1 Then, a pair of second-phase chip inductors L 1 2(1),L 1 2(2) and a pair of fourth phase chip inductors L 1 4(1), L 1 4(2) Series differential connection to form phase B detection circuit 7 1 . Phase A detection circuit 6 1 and B phase detection circuit 7 1 Outputs the amplitude modulated detection signal VA with a 90-degree phase shift 1 ,VB 1 .

[0132] Along the second rotation track O 2 The second group S2 Multiple chip inductors L (outer side) 2 That is, connect the three first-phase chip inductors L 2 1(1),L 2 1(2),L 2 1(3) and 3 third-phase chip inductors L 2 3(1), L 2 3(2), L 2 3(3) Series differential connection, forming A phase detection circuit 6 2 Then, connect the three second-phase chip inductors L 2 2(1),L 2 2(2),L 2 2(3) and 3 fourth phase chip inductors L 2 4(1), L 2 4(2), L 2 4(3) Series differential connection, forming B phase detection circuit 7 2 . Phase A detection circuit 6 2 and B phase detection circuit 7 2 Outputs the amplitude modulated detection signal VA with a 90-degree phase shift 2 ,VB 2 .

[0133] By appropriately processing the detection signal VA with the signal processing circuit 8 1 ,VB 1 , VA 2 ,VB 2 , the rotation position information of the rotor 2 can be obtained. As mentioned above, the first group S 1 Multiple conductor targets T 1 The number of Y 1 With the second group S 2 Conductor target T 2 The number of Y 2 are different from each other, so it is different from using only the detection signal VA 1 ,VB 1 Or use only the detection signal VA 2 ,VB 2 In comparison, it is possible to distinguish and detect the rotational position of a wider rotation angle range. In particular, if the first group S 1 Multiple conductor targets T 1 The number of Y 1 With the second group S 2 Conductor target T 2 The number of Y 2 If they are mutually prime, then one-rotation absolute detection can be performed to distinguish and detect the rotational position within the range of one rotation (360 degrees).

[0134] Although not shown in the figure, a circuit board 10 of the stator 1 is provided for connecting the chip inductor L to form the A-phase AC bridge circuit 6. 1 , 6 2 And B phase AC bridge circuit 7 1 , 7 2 A conductor pattern (more specifically, a copper foil pattern) is provided.

[0135] Fig.14A and 14B 2 is a diagram for further explaining another embodiment. In the above embodiment, each conductor target T is composed of a conductor solid pattern (more specifically, a copper foil solid pattern) formed on the insulating substrate 21. Fig.14A and Fig. 14B As shown in FIG. 1 , each conductor target T may be formed by coil conductor patterns 80 and 90. Fig.14A and Fig. 14B In, yes Figure 3 Corresponding parts of the various parts shown are denoted by the same reference numerals.

[0136] exist Fig.14A In the example of , the multiple independent annular coil conductor patterns 80 constituting the multiple conductor targets T are separated by intervals in the circumferential direction around the rotation axis 3a, thereby being insulated from each other. The multiple conductor targets T constitute a conductor pattern having geometric periodicity along the circumferential direction around the rotation axis 3a. Fig.14A In the figure, the annular coil conductor pattern 80 of each conductor target T is composed of a linear conductor pattern along the outer circumference (contour) of a sector (more precisely, a sector with the inner diameter portion cut off) centered on the rotation axis 3a. However, as shown by the imaginary line, the annular coil conductor pattern 80 can also be composed of a curved (for example, a circular or elliptical) conductor pattern. By forming the conductor target T with such a curved annular coil conductor pattern 80, the output signal waveform can be made close to a sine wave. In addition, in the case where the insulating substrate is a multi-layer wiring substrate, a plurality of conductor patterns respectively formed on a plurality of conductor layers can also be connected to form a multi-winding coil, and the multi-winding coil can be used as each conductor target T.

[0137] exist Fig. 14B In the example of FIG. 1 , a plurality of conductor targets T are connected to each other to form a ring-shaped coil conductor pattern 90 extending over the entire circumference. The ring-shaped coil conductor pattern 90 has geometric periodicity in the circumferential direction around the rotation axis 3a. More specifically, the ring-shaped coil conductor pattern 90 has a predetermined number of periods (in Fig. 14B In the example, the conductor of one cycle constitutes one conductor target T. One conductor target T is the annular coil conductor pattern 90, wherein the angle range (360 degrees) of the entire circumference around the rotation axis 3a is equally divided by the number of cycles (in Fig. 14BThe angle position when divided equally by the number of cycles can be set arbitrarily.

[0138] In the illustrated example, the annular coil conductor pattern 90 includes an outer diameter linear conductor pattern 91 and a radial linear conductor pattern 92 along the outer diameter portion and a pair of radial portions (i.e., portions other than the inner diameter portion) on the outer periphery (contour) of a sector (more precisely, a sector with the inner diameter portion cut out) centered on the rotation axis 3a, respectively, and further includes an inner diameter linear conductor pattern 93 that joins the adjacent radial linear conductor pattern 92 on the inner diameter side. The outer diameter linear conductor pattern 91 joins the adjacent pair of radial linear conductor patterns 92 on the outer diameter side. One radial linear conductor pattern 92 is joined to the outer diameter side end of the other radial linear conductor pattern 92 adjacent to one side in the circumferential direction around the rotation axis 3a via the outer diameter linear conductor pattern 91 on the outer diameter side, and is joined to the inner diameter side end of another radial linear conductor pattern 92 adjacent to the other side in the circumferential direction via the inner diameter linear conductor pattern 93 on the inner diameter side. In this example, the outer diameter linear conductor pattern 91 and the inner diameter linear conductor pattern 93 are formed into a linear shape along an arc centered on the rotation axis 3a. In this way, the annular coil conductor pattern 90 is configured so that the U-shaped coil portion opened toward the rotation axis 3a and the U-shaped coil portion opened toward the opposite side of the rotation axis 3a are continuous in the circumferential direction. In other words, the annular coil conductor pattern 90 is formed into a zigzag wave shape that reciprocates on the inner diameter side and the outer diameter side across the rotation track O.

[0139] like Fig. 14B As shown by the imaginary line in the middle, the loop-shaped coil conductor pattern 90 may also be a curved pattern. By configuring a plurality of conductor targets T with such a curved loop-shaped coil conductor pattern 90, the output signal waveform can be made close to a sine wave.

[0140] Fig.14A and Fig. 14B The operating principle of the structure shown in the embodiment is the same as that of the above-mentioned embodiment. However, in the above-mentioned embodiment, the eddy current flowing through the conductor base pattern constituting the conductor target T is used. Fig.14A and Fig. 14B In the structure, current flows through the coil conductor patterns 80 and 90 constituting the conductor target T. Specifically, when an AC excitation current flows through the excitation coil 12, when the excitation current increases in the direction of the arrow 85, a current in the direction of the arrow 86 flows through the coil conductor patterns 80 and 90 in a manner that does not hinder the change of the magnetic field. The voltage induced in the detection coil constituted by the chip inductor L is affected by the magnetic field of the excitation coil 12 on the stator 1 side and the magnetic field of the coil conductor patterns 80 and 90 (conductor target T) on the rotor 2 side.

[0141] Specifically, in Fig.14AIn the structure, when the detection coil (chip inductor L) is opposite to the area surrounded by the coil conductor pattern 80, the magnetic field of the excitation coil 12 is weakened and the output voltage of the detection coil becomes smaller. Since the relative area changes as the rotor 2 rotates, the output voltage of the detection coil changes accordingly. Fig. 14B In the structure, when the detection coil (chip inductor L) faces the U-shaped coil portion opened toward the rotation axis 3a, the magnetic field of the excitation coil 12 is weakened, and on the other hand, when the detection coil (chip inductor L) faces the U-shaped coil portion opened toward the opposite side of the rotation axis 3a, the magnetic field of the excitation coil 12 is strengthened. Then, the output voltage of the detection coil changes according to the change of the relative area.

[0142] Thus, the rotation position of the rotor 2 can be detected using the change in magnetic field caused by the current flowing through the coil conductor patterns 80 and 90. By using the current flowing through the coil conductor patterns 80 and 90, better detection can be achieved than when using the eddy current flowing through the conductor solid pattern.

[0143] use Fig.14A and Fig. 14B The above-described structure is applicable not only to the first embodiment but also to the second, third, and fourth embodiments.

[0144] FIG. 15A to FIG. 15E Examples of various conductor targets T are shown, and a case where a plurality of conductor targets T are arranged by expanding a rotation track O along a circumference into a straight line is shown. Fig.15A 1 shows a structure in which a conductor target T composed of a plurality of separated conductor basic patterns is arranged at equal intervals. Figure 1 , Figure 3 , Figure 6 , Figure 7 , Fig. 9 , Fig.11 , Fig.12 The structure of etc. is equivalent to this. Fig. 15B 1 shows a structure in which a conductor target T composed of a plurality of separated annular coil conductor patterns is arranged at equal intervals. Fig.14A The structure is equivalent to this.

[0145] Fig. 15C An example is shown in which a plurality of conductor patterns T are formed by a ring-shaped coil conductor pattern extending over the entire circumference. Fig. 14B In this case, as described above, each portion obtained by equally dividing the target by the number of periods of the interval covering the entire circumference of the rotation axis 3a is a conductive target T. Since the division position is arbitrary, for example, Fig.16A , 16B As shown in FIGS. 16C and 16D, each conductor target T can be a variety of shapes in one period.

[0146] Fig.15D This shows an example where a plurality of conductor patterns T are formed by a curved loop coil conductor pattern, which is equivalent to Fig. 14B The structure is represented by an imaginary line in FIG. The conductor target T is a part of one period. For example, in Fig. 14B In the structure of , different annular coil conductor patterns may be formed on both sides of the insulating substrate. In this case, an example of the conductor target T is shown in FIG. 15F.

[0147] The conductor target T is a conductor having one period of a conductor pattern having periodicity (geometric periodicity) formed along the circumference (rotation orbit O) around the rotation axis 3a. Fig.15A and Fig. 15B In the example of Figure 15C to Figure 15E The example is a portion of a continuous conductor pattern.

[0148] As mentioned above, although embodiment of this invention is described, this invention can also be implemented in other forms.

[0149] For example, in the above embodiment, an example is described in which a plurality of chip inductors L are arranged over the entire circumference of the rotation axis 3a, but the plurality of chip inductors L may be arranged in a limited area within an angular range around a portion of the rotation axis 3a. Figure 6 , 7 In embodiment 2 shown in FIG. 8 , the chip inductors L1 ( 2 ), L2 ( 2 ), L3 ( 2 ), and L4 ( 2 ) can be omitted.

[0150] In the above embodiment, an example is shown in which a plurality of chip inductors L are arranged at equal intervals throughout the entire circumference of the rotation axis 3a, but the plurality of chip inductors L do not necessarily have to be arranged at equal intervals. Figure 6 , Figure 7 and Figure 8 In the second embodiment shown, one of the first-phase chip inductors L1(1) and L1(2), one of the second-phase chip inductors L2(1) and L2(2), one of the third-phase chip inductors L3(1) and L3(2), and one of the fourth-phase chip inductors L4(1) are omitted. Even if a structure is adopted in which a plurality of chip inductors are arranged at unequal intervals, detection signals VA and VB with a phase difference of 90 degrees can be obtained.

[0151] In addition, in the above-mentioned embodiment, an example of mounting a chip inductor L on one main surface 10a of the printed substrate 10 of the stator 1 is shown, but a plurality of chip inductors L may be mounted on one main surface 10a of the printed substrate 10, and a plurality of chip inductors L may be mounted on the other main surface 10b of the printed substrate 10. By mounting the chip inductors L on both sides of the printed substrate 10, the number of chip inductors L can be increased, for example, twice the number of chip inductors L can be mounted on the printed substrate 10. The greater the number of chip inductors L, the greater the number of turns overall, and thus the output can be increased. In addition, the greater the number of chip inductors L, the more average the deviation between the chip inductors L, and thus the detection accuracy can be improved. On each of the one main surface 10a and the other main surface 10b of the printed substrate 10, since the distances from the plurality of chip inductors L to the conductor target T are equal, the outputs of the plurality of chip inductors L arranged on each main surface 10a, 10b can be made uniform. Therefore, no complicated signal processing is required.

[0152] In the above-mentioned fourth embodiment, a two-track structure is shown in which two groups of conductor targets and chip inductors are respectively provided along two rotating tracks, but it can also be configured so that three or more groups of conductor targets and chip inductors are respectively provided along three or more rotating tracks.

[0153] In the above-mentioned first, second and fourth embodiments, the example in which the exciting coil is configured in a circular ring shape is shown, but the exciting coil may be configured in other ring shapes such as a polygonal ring shape.

[0154] In the above embodiment, an example of using a stacked chip inductor is described, but a winding chip inductor can also be used. However, since the stacked chip inductor can be configured to be small, it is advantageous to use a stacked chip inductor in order to reduce the conductor target period (i.e., increase the number of conductor targets) to perform position detection with higher resolution. More specifically, even if the width of the conductor target on the rotating track is about 2 mm, a stacked chip inductor with a width of about 1 mm (preferably arranged over the entire circumference of the rotating track) can be used to construct a position detector.

[0155] Although the embodiments of the present invention have been described in detail, these are only specific examples for illustrating the technical content of the present invention, and the present invention should not be construed as being limited to these specific examples. The scope of the present invention is limited only by the appended claims. Description of symbols

[0156] 1 Stator 10 Printed substrate 12 Excitation coil 2 Rotors 20 Printed substrate 21 Insulation substrate 23 Non-conductive part 3 Rotation Axis 3a Axis of rotation 31, 32 Connecting electrodes 5 Excitation source 51 First excitation source 52 Second excitation source 6 A phase detection circuit 7 B phase detection circuit 6 1 Phase A detection circuit 7 1 Phase B detection circuit 6 2 Phase A detection circuit 7 2 Phase B detection circuit 8 Signal processing circuit 12 Excitation coil 121 First excitation coil 122 Second excitation coil 60 A phase AC bridge circuit 61 First A-phase AC voltage application terminal 62 Second A phase AC voltage application terminal 63 First A phase signal detection terminal 64 Second A phase signal detection terminal 70B phase AC bridge circuit 71 first B-phase AC voltage application terminal 72 Second B-phase AC voltage application terminal 73 First B-phase signal detection terminal 74 Second B-phase signal detection terminal 80 Toroidal coil conductor pattern 90 Toroidal Coil Conductor Pattern 100 Inductive Position Detector 200 Inductive Position Detector 300 Inductive Position Detector 400 Inductive Position Detector T Conductor Target O Rotation Orbit λ Conductor target period p Chip Inductor Period L1 First phase chip inductor L2 Second phase chip inductor L3 Third phase chip inductor L4 Fourth phase chip inductor L1(1), L1(2) First phase chip inductor L2(1), L2(2) Second phase chip inductor L3(1), L3(2) third phase chip inductor L4(1), L4(2) Fourth phase chip inductor G1 first phase group G2 Second phase group G3 Phase III Group G4 Fourth Phase Group O 1 The first rotation track O 2 The second rotation track T 1 Conductor Target T 2 Conductor Target L 1 1(1),L 1 1(2) First phase chip inductor L 1 2(1),L 1 2(2) Second phase chip inductor L 1 3(1), L 1 3(2) Third Phase Chip Inductor L 1 4(1), L 1 4(2) Fourth phase chip inductor L 2 1(1),L 2 1(2),L 2 1(3) First phase chip inductor L 2 2(1),L 2 2(2),L 2 2(3) Second phase chip inductor L 2 3(1), L 2 3(2), L 2 3(3) Third Phase Chip Inductor L 2 4(1), L 2 4(2), L 2 4(3) Fourth phase chip inductor S 1 Group 1 S 2 Group 2.

Claims

1. An inductive position detector, characterized in that: Include: a stator having a wiring substrate; a rotor having a non-conductive member disposed opposite to the stator and rotating relative to the stator around a predetermined rotation axis; a plurality of conductor targets having the same shape and size, periodically arranged along a circumference around the rotation axis and held on the non-conductor component of the rotor, and moving along a rotation track around the rotation axis as the rotor rotates; as well as A plurality of chip inductors are arranged to be opposite to the rotating track at different spatial phases relative to the plurality of conductor targets, and are surface-mounted on the main surface of the wiring substrate of the stator, each constituting a plurality of detection coils for detecting changes in the magnetic field accompanying the passage of the conductor target.

2. The inductive position detector according to claim 1, characterized in that: The conductor targets are arranged along the rotating track at a predetermined conductor target period. The chip inductor has a coil width along the rotating track that is 25% to 75% of a period of the conductor target.

3. The inductive position detector according to claim 1 or 2, characterized in that: The conductor targets are arranged along the rotating track at a predetermined conductor target period. The plurality of chip inductors include at least one first-phase chip inductor, at least one second-phase chip inductor, at least one third-phase chip inductor, and at least one fourth-phase chip inductor arranged with a quarter-cycle phase difference relative to the conductor target period.

4. The inductive position detector according to any one of claims 1 to 3, characterized in that: 4N (N is a natural number) chip inductors are arranged at equal intervals throughout the entire circumference of the rotating track and along the rotating track. The number Y (Y is a natural number) of the conductor targets is represented by Y=4NM±N (M is a natural number).

5. The inductive position detector according to any one of claims 1 to 4, characterized in that: The stator and the rotor are used to share the first rotating track as the first group of the plurality of conductor targets and the plurality of chip inductors, and the second rotating track different from the first rotating track as the second group of the plurality of conductor targets and the plurality of chip inductors. The number Y1 (Y1 is a natural number) of the plurality of conductor targets of the first group and the number Y2 (Y2 is a natural number) of the plurality of conductor targets of the second group are different from each other.

6. The inductive position detector according to claim 5, characterized in that: The number Y1 of the plurality of conductor targets of the first group and the number Y2 of the plurality of conductor targets of the second group are mutually prime.

7. The inductive position detector according to claim 5 or 6, characterized in that: It also includes an excitation coil, which is provided on the wiring substrate of the stator and is used to induce a voltage in the plurality of chip inductors of the first group and the plurality of chip inductors of the second group so as to be shared.

8. The inductive position detector according to claim 7, characterized in that: The excitation coil includes: a first excitation coil, the first excitation coil being ring-shaped and enclosing the plurality of chip inductors of the first group and the plurality of chip inductors of the second group when viewed along the rotation axis; and a second excitation coil, which is ring-shaped and is arranged around the rotation axis in a manner of being enclosed by the plurality of chip inductors of the first group and the plurality of chip inductors of the second group when viewed along the rotation axis.

9. The inductive position detector according to any one of claims 1 to 8, characterized in that: Each of the conductor targets includes a conductor solid pattern or an annular coil conductor pattern formed on the non-conductor member, and the plurality of conductor targets are insulated from each other.

10. The inductive position detector according to any one of claims 1 to 8, characterized in that: The plurality of conductor targets are connected to each other to form a ring-shaped coil conductor pattern extending over the entire circumference.

11. The inductive position detector according to any one of claims 1 to 10, characterized in that: The chip inductor is a stacked chip inductor having a pair of connection electrodes at both ends.

12. The inductive position detector according to any one of claims 1 to 11, characterized in that: It also includes an excitation coil, which is arranged on the wiring substrate of the stator and is formed into a ring shape that encloses the multiple chip inductors when viewed along the rotation axis, and generates a magnetic field for inducing voltage in the multiple chip inductors.

13. The inductive position detector according to any one of claims 1 to 12, characterized in that: The plurality of chip inductors are connected in such a manner as to form an AC bridge circuit having a pair of AC voltage applying terminals and a pair of signal detecting terminals.

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