Position detection device

Abstract

To provide a position detection device capable of precisely detecting a position with high resolution.SOLUTION: A position detection device includes: a moving body 13 that is long, is provided movable along its longitudinal direction, and has multiple conductive detected sections 15a, 15b, 15c, 15d provided along the longitudinal direction; a first detection section 20 and a second detection section 25 that are disposed along the movement direction of the moving body 13, and are provided opposingly with a predetermined gap to the respective detected sections 15a, 15b, 15c, 15d of the moving body 13; and displacement detection sections 40, 41 that process output signals from the first detection sections 20 and the second detection section 25 and detect displacement of the moving body 13. The first detection section 20 and the second detection section 25 have winding wire coils 21, 26 for forming an LC circuit and capacitors 22, 27 connected between both the ends of the winding wire coils 21, 26, respectively.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a contact-type position detection device. [Background technology]

[0002] A known contact-type position detector is the position detector disclosed in Japanese Patent Laid-Open Publication No. 2003-161635. This position detector includes a hollow cylindrical coil and an axial moving body that is inserted into the coil and moves within the coil, and patterns with different electrical conductivity or magnetic resistance are formed on the outer circumferential surface of the axial moving body, and the width of the patterns decreases or increases along the axial direction of the axial moving body.

[0003] This position detector detects the displacement of the axial moving body by periodically applying a square wave to the coil. When the axial moving body moves, the overlapping distance or overlapping area between the coil and the pattern changes according to the displacement, which changes the inductance of the coil and the attenuation state of the square wave. Therefore, by measuring the attenuation state of this square wave, the linear displacement of the axial moving body can be detected.

[0004] In other words, this position detector utilizes the phenomenon that, due to the positional relationship between the coil and the axial moving body, which is a conductor, an induced current is generated in the axial moving body, causing a change in the inductance of the coil, and the displacement of the axial moving body is detected by extracting the change in the coil inductance as a frequency component. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-161635 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, the resolution of position detection in the above-mentioned conventional position detector is calculated as Δf / Δd, where Δd is the amount of change (displacement) in the position of the axial moving body and Δf is the change in frequency before and after the position change of the axial moving body. Therefore, in order to increase the resolution, it is necessary to increase the change in frequency (Δf).

[0007] On the other hand, to detect position over long distances, it is necessary to increase the coil length (the length of the coil in the width direction). However, the change in frequency at which the change in coil inductance can be extracted does not increase in proportion to the length of the coil. Conversely, when increasing the coil length to detect position over long distances, it is necessary to keep the position detection resolution low in order to ensure measurement accuracy.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a position detection device that can detect a position with high resolution and high accuracy even when the detection distance is long. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides: a moving body having an elongated shape, movable along its longitudinal direction, and having a plurality of conductive detection targets provided along the longitudinal direction; a plurality of relative displacement detection units arranged along a moving direction of the moving body and arranged to be opposed to each of the detection targets of the moving body at a predetermined interval, for detecting a relative displacement of the moving body; a position calculation unit that processes each output signal from the relative displacement detection unit to calculate a displacement of the moving object, Each of the relative displacement detection units relates to a position detection device including a winding coil for forming an LC circuit and a capacitor connected between both ends of the winding coil.

[0010] According to the position detection device of this aspect (first aspect), the displacement of the moving body is detected as follows. That is, when the moving body moves, the oscillation frequency of each relative displacement detection unit having an LC circuit varies sinusoidally, and each oscillation frequency is acquired by a position calculation unit. Then, the position calculation unit calculates the displacement of the moving body based on the correlation between the variation of each oscillation frequency and the displacement of the moving body.

[0011] In this case, since the relative displacement detection units are arranged along the moving direction of the moving body, the fluctuations of the oscillation frequencies extracted from the relative displacement detection units are sine waves with mutually phase-shifted fluctuations. Since the change in oscillation frequency of a sine wave is small relative to the position change of the moving body near its upper and lower peaks, if the position change of the moving body is calculated based on the change in oscillation frequency near these peaks, the position change of the moving body cannot be detected with high accuracy (high resolution).

[0012] On the other hand, between the peaks excluding the vicinity of the peaks (hereinafter, between the peaks), the oscillation frequency changes significantly with respect to the position change of the moving body, so between the peaks, the position change of the moving body can be detected with high accuracy (high resolution) based on the change in oscillation frequency. Therefore, in the position detection device according to the present invention, the position change of the moving body can be detected with high accuracy (high resolution) by selectively using the change in oscillation frequency between the peaks excluding the vicinity of the peaks of the sine waves in each relative displacement detection unit whose phase is shifted. In this way, the position detection device according to the present invention can detect the position change of the moving body with high accuracy (high resolution).

[0013] The position detection device of the first aspect further includes: an absolute position detection unit for detecting an absolute position of the moving body, the absolute position detection unit being provided on one side or the other side of the relative displacement detection unit in a moving direction of the moving body so as to be opposed to each of the detection target parts of the moving body at the predetermined interval; the absolute position detection unit includes a winding coil for forming an LC circuit, the winding coil having a length longer than that of the winding coil of the relative displacement detection unit, and a capacitor connected between both ends of the winding coil; The position calculation section may adopt an aspect (second aspect) configured to process output signals from the relative displacement detection section and the absolute position detection section to detect the position of the moving body.

[0014] According to this position detection device, an absolute position detection section having a winding coil longer than that of the relative displacement detection section is provided, and thus the absolute position detection section can detect long distance movement of the moving body. Therefore, by using the absolute position detection section together with the relative displacement detection section, the position calculation section can detect a rough absolute position (absolute position) of the moving body from the oscillation frequency of the absolute position detection section, and in addition, can detect a highly accurate (high resolution) displacement (increment position) of the moving body from a change in the oscillation frequency of the relative displacement detection section. As a result, the position calculation section can detect the absolute position of the moving body with high accuracy (high resolution).

[0015] In the position detection device according to the first or second aspect, The relative displacement detection unit is provided in a number of n, each of the winding coils has the same length, and each winding coil has a length L and is arranged at intervals of (L±L / n) from each other, Each detectable portion of the moving body can have a width in the longitudinal direction that is the same as the length of the winding coil of the relative displacement detection portion, and can be arranged at a distance corresponding to the length of the winding coil of the relative displacement detection portion.

[0016] In addition, in the position detection device according to any one of the first to third aspects, Each of the winding coils has a hollow cylindrical shape, The movable body may have an axial shape, and the detected portion may have a cylindrical shape and may be provided so as to be insertable into each of the winding coils (fourth embodiment).

[0017] Alternatively, in the position detection device according to any one of the first to third aspects, It is possible to adopt an embodiment (fifth embodiment) in which each of the winding coils is a planar coil.

[0018] The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of: a moving body having an elongated shape, movable along its longitudinal direction, and having a plurality of conductive detection targets provided along the longitudinal direction; a plurality of relative displacement detection units arranged to be opposed to each of the detection target portions of the moving body at a predetermined interval, arranged side by side in a direction perpendicular to the moving direction of the moving body, and arranged to move back and forth relative to each other along the moving direction, for detecting a relative displacement of the moving body; a position calculation unit that processes each output signal from the relative displacement detection unit to calculate a displacement of the moving object, Each of the relative displacement detection units relates to a position detection device including a wound coil, which is a planar coil for forming an LC circuit, and a capacitor connected between both ends of the wound coil.

[0019] According to the position detection device of this aspect (sixth aspect), similarly to the position detection device of the first aspect, the displacement of the moving body is detected as follows. That is, when the moving body moves, the oscillation frequency of the relative displacement detection unit having an LC circuit varies sinusoidally, and each of these oscillation frequencies is acquired by the position calculation unit. Then, the position calculation unit calculates the displacement of the moving body based on the correlation between the variation of each oscillation frequency and the displacement of the moving body.

[0020] In this case, since the relative displacement detection unit is disposed so as to move back and forth along the moving direction of the moving body, the fluctuations in the oscillation frequency extracted from the relative displacement detection unit are sine waves with mutual phase shifts. Since the change in oscillation frequency of the sine wave is small relative to the position change of the moving body near its upper and lower peaks, if the position change of the moving body is calculated based on the change in oscillation frequency near these peaks, the position change of the moving body cannot be detected with high accuracy (high resolution).

[0021] On the other hand, between the peaks, excluding the vicinity of the peaks, the oscillation frequency changes significantly with respect to the position change of the moving body, so between these peaks, the position change of the moving body can be detected with high accuracy (high resolution) based on the change in oscillation frequency. Therefore, in the position detection device according to the present invention, by selectively using the change in oscillation frequency between the peaks, excluding the vicinity of the peaks, of each sine wave in the relative displacement detection unit in which the phase is shifted, the position change of the moving body can be detected with high accuracy (high resolution). In this way, the position detection device according to the present invention can detect the position change of the moving body with high accuracy (high resolution).

[0022] The position detection device of the sixth aspect further comprises: an absolute position detection unit provided on one side or the other side of the relative displacement detection unit in the moving direction of the moving body, the absolute position detection unit being capable of facing each of the detection targets of the moving body at the predetermined interval, the absolute position detection unit includes a winding coil, which is a planar coil for forming an LC circuit, and a capacitor connected between both ends of the winding coil, and the winding coil of the absolute position detection unit has a length longer than that of the winding coil of the relative displacement detection unit; The position calculation section may adopt an aspect (seventh aspect) configured to process output signals from the relative displacement detection section and the absolute position detection section to detect the displacement of the moving body.

[0023] According to this position detection device, as in the position detection device of the second aspect, an absolute position detection section having a winding coil longer than the winding coil of the relative displacement detection section is provided, so that the absolute position detection section can detect long distance movement of the moving body. Therefore, by using this absolute position detection section together with the relative displacement detection section, the position calculation section can detect a rough absolute position (absolute position) of the moving body from a change in the oscillation frequency of the absolute position detection section, and in addition, can detect a highly accurate (high resolution) displacement (increment position) of the moving body from a change in the oscillation frequency of the relative displacement detection section. As a result, the position calculation section can detect the absolute position of the moving body with high accuracy (high resolution).

[0024] In the position detection device according to the sixth or seventh aspect, the number of the relative displacement detection units is n, each of the winding coils has the same length, and each winding coil is disposed in front of or behind the other in the moving direction by a distance corresponding to (L±L / n), where L is the length of the winding coil; An eighth embodiment can be adopted in which the width in the longitudinal direction of each detected portion of the moving body is set to be the same as the length of the winding coil of the relative displacement detection portion. Effect of the Invention

[0025] According to the present invention, by selectively using the change in oscillation frequency between peaks, excluding the vicinity of the peaks, of each sine wave in each relative displacement detection unit in which the phase is shifted, it is possible to detect the position change of a moving body with high accuracy (high resolution).

[0026] Furthermore, by providing an absolute position detection section having a winding coil longer than that of the relative displacement detection section, the absolute position detection section can detect long distance movement of the moving body. By using the absolute position detection section and the relative displacement detection section in combination, the position calculation section can detect the absolute position of the moving body from the change in the oscillation frequency of the absolute position detection section, and in addition, can detect the displacement (increment position) of the moving body with high accuracy (high resolution) from the change in the oscillation frequency of the relative displacement detection section. As a result, the position calculation section can detect the absolute position of the moving body with high accuracy (high resolution). [Brief description of the drawings]

[0027] [Figure 1] 1 is a perspective view showing a position detection device according to an embodiment of the present invention; [Diagram 2] 1 is a front view showing a position detection device according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a right side view showing the position detection device according to the embodiment. [Figure 4] FIG. 2 is an explanatory diagram equivalent to a plan view, partly in a block diagram, illustrating a schematic configuration of a measurement unit according to the present embodiment; [Diagram 5] 5(a) is a left side view of the moving body shown in FIG. 4, and (b) is a side view of each of the winding coils that constitute the first detection unit, the second detection unit, and the third detection unit shown in FIG. [Figure 6] 11 is a graph showing the relationship between the positional relationship between a moving body and a winding coil, and the oscillation frequency. [Figure 7] 11 is a graph showing the relationship between the positional relationship between a moving body and a winding coil, and the oscillation frequency. [Figure 8] 11 is a graph showing the relationship between the positional relationship between a moving body and a winding coil, and the oscillation frequency. [Figure 9] 11 is a graph showing the relationship between the positional relationship between a moving body and a winding coil, and the oscillation frequency. [Figure 10]11 is a data table showing data stored in a data storage unit according to the present embodiment, relating to the relationship between the position of a moving body and the oscillation frequency obtained from each winding coil. [Figure 11] 13A and 13B are explanatory diagrams showing modified examples of the detection unit according to the embodiment. [Figure 12] 13A and 13B are explanatory diagrams showing modified examples relating to the positional relationship between a moving body and a winding coil. [Figure 13] FIG. 13 is an explanatory diagram showing a modified example of the moving body. [Figure 14] FIG. 13 is an explanatory diagram showing a modified example of the moving body. [Figure 15] 13 is an explanatory diagram equivalent to a plan view showing a modified example of the moving body and the winding coil. FIG. [Figure 16] FIG. 16 is a front view of the moving body and the winding coil shown in FIG. [Figure 17] 16 is an explanatory diagram equivalent to a bottom view showing a further modified example of the moving body applicable to the modified example shown in FIG. 15. FIG. [Figure 18] 16 is an explanatory diagram equivalent to a plan view showing a further modified example regarding the arrangement of the first detection unit, the second detection unit and the third detection unit in the modified example shown in FIG. 15. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. As shown in Figures 1 to 3, a position detection device 1 of this embodiment comprises a measurement unit 10 and a display unit 50 which are integrally connected to each other.

[0029] The display unit 50 is configured to include a box-shaped case 51, a display control unit (not shown) housed in the case 51, and a liquid crystal panel 52 housed in the case 51 so as to be exposed to the outside from an opening 51a of the case 51 and connected to the display control unit (not shown). The measured value measured by the measurement unit 10 is displayed on the liquid crystal panel 52 under the control of the display control unit (not shown).

[0030] The measurement unit 10 is composed of a case 11, a probe 12, a moving body 13, a first detection unit 20 and a second detection unit 25 as relative displacement detection units, a third detection unit 30 as an absolute position detection unit, an oscillation control / frequency converter 40, a position calculation unit 41, and a data storage unit 42 (see Figures 1 to 4).

[0031] Case 11 is box-shaped and connected to case 51. Probe 12 is axially shaped, with one end extending outward from the bottom surface of case 11 and the other end located within case 11, and is held by case 11 in a state in which it can advance and retreat in a direction along its axis and is biased in the advancing direction.

[0032] The moving body 13, first detection unit 20, second detection unit 25, third detection unit 30, oscillation control / frequency converter 40, position calculation unit 41 and data storage unit 42 are each provided inside a case 11. The moving body 13 comprises a shaft portion 14 connected to the probe 12 so as to be coaxial with the probe 12, and a plurality of detection targets 15a, 15b, 15c, and 15d (four in this example) fitted onto the shaft portion 14.

[0033] As shown in FIG. 5(a), the shaft portion 14 has a solid cylindrical shape. The detection target portions 15a, 15b, 15c, and 15d have a hollow cylindrical shape and are fitted onto the shaft portion 14 at a predetermined equal interval. There is no limitation on the material of the shaft portion 14, but from the viewpoint of realizing high measurement accuracy, it is preferable to use stainless steel. The detection target portions 15a, 15b, 15c, and 15d may be conductive, and there are no other limitations on the material, but preferred materials include copper and aluminum. In this example, four detection target portions 15a, 15b, 15c, and 15d are provided as an example, but the number of detection target portions is not limited to three or less (one or more), or five or more.

[0034] The first detection unit 20 is composed of a first coil 21, which is a wound coil, and a capacitor 22 connected between both ends 21a and 21b of the first coil 21. The second detection unit 25 is composed of a second coil 26, which is also a wound coil, and a capacitor 27 connected between both ends 26a and 26b of the second coil 26. Similarly, the third detection unit 30 is composed of a third coil 31, which is a wound coil, and a capacitor 32 connected between both ends 31a and 31b of the third coil 26. The first detection unit 20, the second detection unit 25, and the third detection unit 30 are LC circuits composed of the first coil 21, the second coil 26, the third coil 31, and the capacitors 22, 27, and 32, respectively, and are electrically oscillated by the inductance components of the first coil 21, the second coil 26, and the third coil 31 and the capacitance components of the capacitors 22, 27, and 32.

[0035] As shown in FIG. 5(b), the first coil 21, the second coil 26, and the third coil 31 have a hollow cylindrical shape, and as shown in FIG. 4, they are arranged in a positional relationship in which they are coaxial with each other and with the moving body 13. The first coil 21 and the second coil 26 have the same coil length (coil width) L, and the distance (spacing) between them is L / 2. The coil length of the third coil 31 is set according to the length measurement performance (measurable length) of the position detection device 1. In this example, the third coil 31 is arranged closest to the moving body 13, followed by the first coil 21 and the second coil 26, and the interval between the third coil 31 and the first coil 21 is set to an appropriate interval according to the measurement accuracy. In other words, the third coil 31 and the first coil 21 are conductors, and if they are arranged too close, they will affect each other, so they are arranged at a distance that reduces this influence.

[0036] The width dimension along the axial direction of the detected parts 15a, 15b, 15c, and 15d of the movable body 13 is the same as the coil length of the first coil 21 and the second coil 26, and the distance between them is also set to the same dimension L as the coil length. In addition, the outer diameters of the detected parts 15a, 15b, 15c, and 15d are set as large as possible so that the detected parts 15a, 15b, 15c, and 15d can pass through the first coil 21, the second coil 26, and the third coil 31 without coming into contact with them.

[0037] The oscillation control / frequency converter 40 is composed of electric and electronic circuits, and is connected to both ends 21a, 21b of the first coil 21, both ends 26a, 26b of the second coil 26, and both ends 31a, 31b of the third coil 31. The oscillation control / frequency converter 40 is a device that controls the oscillation of the first detection unit 20, the second detection unit 25, and the third detection unit 30, and converts the oscillation frequency of each LC circuit into a digital value and outputs it.

[0038] As shown in Fig. 6(a), for example, when the conductor part 15a to be detected is moved in the direction of the arrow and passes through the first coil 21, the oscillation frequency of the LC circuit formed by the first coil 21 changes as shown in Fig. 6(b). In Fig. 6(b), the conductor position is the relative positional relationship between the part 15a to be detected and the first coil 21. As the part 15a to be detected enters the first coil 21, the oscillation frequency of the LC circuit increases, and when the part 15a to be detected overlaps with the first coil 21, the oscillation frequency becomes maximum (peaks), and as the part 15a to be detected leaves the first coil 21, the oscillation frequency of the LC circuit decreases. In this way, the oscillation frequency of the LC circuit draws a sine wave that changes depending on the relative positional relationship between the part 15a to be detected and the first coil 21.

[0039] The oscillation control / frequency converter 40 detects the oscillation frequencies of the first detector 20, the second detector 25 and the third detector 30, which change depending on the positional relationship with the detected parts 15a, 15b, 15c and 15d, and outputs these as digital values. The detection of the oscillation frequency in the oscillation control / frequency converter 40 is performed at a predetermined sampling interval.

[0040] 6, in the case of such a sine wave, the change in oscillation frequency (Δf) relative to the relative position change (ΔD) between the detected part 15a and the first coil 21 is small near the upper and lower peaks of the sine wave, so it is difficult to detect the position change (ΔD) with high accuracy (high resolution) from the change in oscillation frequency (Δf) near the peaks. On the other hand, the portion excluding the peaks, i.e., the portion between the peaks (between peaks), has a large slope and the change in oscillation frequency (Δf) relative to the position change (ΔD) is also large, so the position change (ΔD) can be detected with high accuracy (high resolution) from the change in oscillation frequency (Δf).

[0041] Therefore, in this example, a configuration is adopted in which a plurality of detectable parts 15a, 15b, 15c, and 15d are formed on the moving body 13, and a third detection unit 30, a first detection unit 20, and a second detection unit 25 are arranged on the movement path of the moving body 13. The third detection unit 30 is for detecting the position of the moving body 13 on the set movement path as an absolute position, and the first detection unit 20 and the second detection unit 25 are for detecting the position of the moving body 13 as an incremental position (relative position).

[0042] The position calculation unit 41 calculates the position of the moving object 13 along the axial direction based on the oscillation frequencies output from the first detection unit 20, the second detection unit 25, and the third detection unit 30 at predetermined sampling intervals and the data stored in the data storage unit 42, and outputs the calculated position data to the display unit 50. The display unit 50 displays the position data transmitted from the position calculation unit 41 on a liquid crystal panel 52 under the control of the display control unit (not shown). The data storage unit 42 has the data table shown in FIG. 10 stored therein in advance.

[0043] Next, the principle of position detection in this embodiment will be described. [Position detection principle] As shown in Fig. 7(a), when the movable body 13 is moved in the direction of the arrow, which is the direction along its axis, and passes through the first coil 21 of the first detection unit 20, the oscillation frequency of the LC circuit taken out from the first coil 21 changes as shown in Fig. 7(b). That is, the oscillation frequency shows an upper peak value at the position where the detected parts 15a, 15b, 15c, and 15d overlap with the first coil 21, and shows a lower peak value at the position where the detected parts 15a, 15b, 15c, and 15d do not overlap with the first coil 21, drawing a sine wave with a wavelength λ of 2L.

[0044] As shown in Figure 8, in the movement direction (displacement direction, arrow direction) of the movable body 13, the second coil 26 of the second detection unit 25 is arranged downstream of the first coil 21 of the first detection unit 20 with a gap of L / 2, and when the movable body 13 is moved in the direction of the arrow along its axis and passes through the first coil 21 of the first detection unit 20 and the second coil 26 of the second detection unit 25, the oscillation frequency of the LC circuit extracted from the first coil 21 changes with a sine wave as shown by the solid line in Figure 8(b), and the oscillation frequency of the LC circuit extracted from the second coil 26 also changes with a sine wave as shown by the dashed dotted line in Figure 8(b).

[0045] 8(b), the change in the oscillation frequency of the first coil 21 is ahead of the change in the oscillation frequency of the second coil 26 in phase by λ / 4 (=L / 2). That is, the change in the oscillation frequency waveform (sine wave) of the first coil 21 and the change in the oscillation frequency waveform (sine wave) of the second coil 26 are in a state where the vicinity of the peak of one waveform overlaps with the interval between the peaks of the other waveform in the moving direction of the moving body 13. In this example, since the objective is to set the phase difference to ±λ / 4, the interval between the first coil 21 and the second coil 26 can also be 3L / 2.

[0046] As described above, it is difficult to detect the position change (ΔD) with high accuracy (high resolution) from the change in oscillation frequency (Δf) near the upper and lower peaks of the sine wave, but conversely, it is possible to detect the position change (ΔD) with high accuracy (high resolution) from the change in oscillation frequency (Δf) between the peaks (peak to peak). Figure 8(c) shows the frequency change (Δf) per unit length for the oscillation frequency of the first coil 21 and the oscillation frequency of the second coil 26 shown in Figure 8(b). The graph in Figure 8(c) is a derivative of the graph shown in Figure 8(b).

[0047] In each waveform shown in FIG. 8(c), the part above the upper dashed line and the part below the lower dashed line are ranges where the change in frequency (Δf) is large. This region corresponds to the peaks of each waveform shown in FIG. 8(b), and is a region where the position change (ΔD) can be detected with high accuracy (high resolution) from the change in oscillation frequency (Δf). The waveforms of each oscillation frequency between the peaks are continuous in the moving direction of the moving body 13. Therefore, by selectively using the oscillation frequency whose changing waveform corresponds to the peaks among the oscillation frequency extracted from the first coil 21 and the oscillation frequency extracted from the second coil 26, the position of the moving body 13 can be detected with high accuracy. In order to make this point easier to understand, an example of the use region of the oscillation frequency of the first coil 21 and the use region of the oscillation frequency of the second coil 26 is illustrated in FIG. 8(b) and (c). In this example, only the part of about 70% or more of the peak of Δf is used.

[0048] Then, by using the oscillation frequency extracted from the first coil 21 and the second coil 26, it is possible to detect how far the moving body 13 has been displaced from a certain position, that is, it is possible to detect the displacement of the moving body 13 as an increment value (relative value).

[0049] 9, the third coil 31 of the third detection unit 30 is disposed at a predetermined interval upstream of the first coil 21 of the first detection unit 20 in the moving direction of the moving body 13. In this state, when the moving body 13 is moved in the direction of the arrow along its axis and passes through the third coil 31 of the third detection unit 30, the first coil 21 of the first detection unit 20, and the second coil 26 of the second detection unit 25, the oscillation frequency of the LC circuit taken out from the first coil 21 changes in a sine wave as shown in FIG. 9(b), the oscillation frequency of the LC circuit taken out from the second coil 26 changes in a sine wave as shown in FIG. 9(c), and the oscillation frequency of the LC circuit taken out from the third coil 31 changes as shown in FIG. 9(d).

[0050] When the moving body 13 passes through the third coil 31 of the third detection unit 30, the oscillation frequency of the LC circuit extracted from the third coil 31 peaks when the last three detectable parts in the moving direction, i.e., the detectable parts 15b, 15c, and 15d, are inside the third coil 31, and as shown in Fig. 9(d), the oscillation frequency gradually decreases as the detectable parts 15b, 15c, and 15d pass by in sequence, and changes almost linearly overall. Since the change (Δf) in the oscillation frequency with respect to the relative position change (ΔD) between the moving body 13 and the third coil 31 is small, it is difficult to detect the position change (ΔD) with high accuracy (high resolution) from the change (Δf) in the oscillation frequency, but it is possible to detect the rough absolute position of the moving body 13 from the oscillation frequency extracted from the third coil 31.

[0051] 9, a rough absolute position (low-resolution position) of the moving body 13 can be detected from the oscillation frequency extracted from the third coil 31, and a highly accurate displacement (high-resolution displacement) as an increment value (relative value) of the moving body 13 can be detected from the oscillation frequencies extracted from the first coil 21 and the second coil 26. Therefore, by using both the oscillation frequency extracted from the third coil 31 and the oscillation frequencies extracted from the first coil 21 and the second coil 26, the absolute position of the moving body 13 can be detected with high accuracy.

[0052] 9 illustrates the relationship between the oscillation frequencies extracted from the first coil 21, the second coil 26, and the third coil 31 and the specific position of the moving body 13. However, this is merely an example for the purpose of explanation, and there is no guarantee that this will be reproduced in a specific example.

[0053] 9(b) and (c), the oscillation frequencies extracted from the first coil 21 and the second coil 26 respectively have a maximum value of 2.000 MHz and a minimum value of 1.000 MHz, and the range (range between peaks) that can be used as high resolution is a range of 1.300 MHz to 1.800 MHz, and the corresponding displacement of the moving body 13 is L / 2. If L=2 mm, the displacement that can be detected as high resolution is 1 mm. Also, the oscillation frequency extracted from the third coil 31 has a maximum value of 3.00 MHz and a minimum value of 1.00 MHz, and the displacement of the moving body 13 is 0 mm when the oscillation frequency is 3.00 MHz and 10 mm when the oscillation frequency is 1.00 MHz.

[0054] The relationship between the displacement of the moving body 13 and the oscillation frequencies extracted from the first coil 21, the second coil 26, and the third coil 31 is obtained in advance by calibration, and these correlations are stored as a data table in the data storage unit 42. During calibration, for example, each oscillation frequency can be obtained with the displacement of the moving body 13 in units of 1 μm, but this is not limited to this. An example of the data table is shown in FIG. 10. In FIG. 10, the positions are spaced at intervals of 0.001 mm (=1 μm).

[0055] The position calculation unit 41 acquires the oscillation frequencies respectively extracted from the first coil 21, the second coil 26, and the third coil 31 from the oscillation control / frequency converter 40, and calculates the displacement (position) of the moving body 13 by referring to a data table stored in the data storage unit 42. For example, if the oscillation frequency of the third coil 31 is 2.78 MHz, the position calculation unit 41 estimates the position of the moving body 13 corresponding to this 2.78 MHz to be, for example, a position of 0.55 mm (=550 μm) by referring to the data table stored in the data storage unit 42. Next, the position calculation unit 41 refers to the oscillation frequencies of the first coil 21 and the second coil 26, and uses the oscillation frequency that is within the range of 1.3 MHz to 1.8 MHz.

[0056] For example, if the oscillation frequency of the first coil 21 is 1.530 MHz and the oscillation frequency of the second coil 26 is 1.005 MHz, the position calculation unit 41 uses the oscillation frequency of the first coil 21, 1.530 MHz, and calculates the displacement of the moving body 13 using this 1.530 MHz. Specifically, using 0.55 mm (=550 μm), which is the position of the moving body 13 calculated from the oscillation frequency (2.78 MHz) of the third coil 31, as a reference, the positional deviation (displacement) relative to this position is calculated to determine the position of the moving body 13. Since the oscillation frequency of the first coil 21 at the reference position is 1.525 MHz, the position calculation unit 41 calculates the displacement when the oscillation frequency of the first coil 21 is 1.530 MHz by interpolation processing. 9(b), the relationship between the change in oscillation frequency Δf and the displacement ΔD, i.e., ΔD / Δf, is ΔD / Δf=1 mm / 0.5 MHz=2 mm / MHz, and since Δf is 0.005 MHz, the positional deviation (displacement) ΔD is ΔD=2000 μm×0.005 MHz=10 μm. From the above, the position of the movable body 13 (displacement as an absolute amount) is 0.55+0.01=0.56 mm (=560 μm).

[0057] In the example shown in Fig. 10, the position of the moving body 13 is expressed in units of 10 µm, and a data table is shown which indicates the correlation between the position of the moving body 13 and the oscillation frequencies of the first coil 21, the second coil 26, and the third coil 31. However, the present invention is not limited to this, and the position of the moving body 13 may be expressed in units larger than 10 µm, or conversely, in units smaller than 10 µm. When a larger unit is used, the absolute position of the moving body 13 calculated from the oscillation frequency of the third coil 31 can be calculated in fine units by an interpolation process. As for the displacement of the moving body 13 from the reference position calculated from the oscillation frequency of the third coil 31, a displacement with higher resolution can be calculated by an interpolation process using the oscillation frequencies of the first coil 21 and the second coil 26.

[0058] As described above, according to the position detection device 1 of this embodiment, it is possible to detect a rough absolute position (low-resolution position) of the moving body 13 from the oscillation frequency extracted from the third coil 31, and to detect a highly accurate displacement (high-resolution displacement) as an increment value (relative value) of the moving body 13 from the oscillation frequencies extracted from the first coil 21 and the second coil 26. Therefore, by using both the oscillation frequency extracted from the third coil 31 and the oscillation frequencies extracted from the first coil 21 and the second coil 26, it is possible to detect the absolute position of the moving body 13 with high accuracy.

[0059] Although specific embodiments of the present invention have been described above, the specific aspects that the present invention can adopt are not limited to the above examples.

[0060] For example, in the above example, two relative displacement detection units, the first detection unit 20 and the second detection unit 25, are provided as relative displacement detection units that detect increment values ​​(relative values) of the displacement of the moving body 13, but the number of relative displacement detection units that can be provided is not limited to two, and three or more relative displacement detection units can be provided. As one example, an example in which three relative displacement detection units are provided is shown in FIG. 11.

[0061] The example shown in Fig. 11(a) corresponds to the position detection device 1 shown in Fig. 4 provided with a fourth detection unit 35 as a relative displacement detection unit, but in this example, the interval between the first coil 21 and the second coil 26 is set to 2L / 3. Like the first detection unit 20 and the second detection unit 25, the fourth detection unit 20 is composed of a fourth coil 36 which is a wound coil and a capacitor (not shown) connected between both ends thereof, and both ends of the fourth coil 36 are connected to the oscillation control / frequency converter 40. Note that the third coil 31 shown in Figs. 4 and 9 is not shown in Fig. 11(a).

[0062] The fourth coil 36 has a hollow cylindrical shape like the first coil 21 and the second coil 26, and is disposed coaxially therewith, to the right of the second coil 26 in the direction of the arrow in Fig. 11, with a distance of 2L / 3 therebetween. The coil length of the fourth coil 36 is the same length L as the coil lengths of the first coil 21 and the second coil 26. The distance between each coil is set according to the number of coils, and when n coils are provided, the distance is generalized to (L±L / n).

[0063] In this example, as shown in Figure 11(a), when the movable body 13 is moved in the direction of the arrow along its axis and passes through the first coil 21 of the first detection unit 20, the second coil 26 of the second detection unit 25, and the fourth coil 36 of the fourth detection unit 35, the oscillation frequency of the LC circuit extracted from the first coil 21 changes in a sine wave as shown by the solid line in Figure 11(b), the oscillation frequency of the LC circuit extracted from the second coil 26 changes in a sine wave as shown by the dotted line in Figure 11(b), and the oscillation frequency of the LC circuit extracted from the fourth coil 36 changes in a sine wave as shown by the dotted line in Figure 11(b).

[0064] As can be seen from Figure 11 (b), the change in the oscillation frequency of the second coil 26 leads in phase by λ / 6 (= L / 3) from the change in the oscillation frequency of the fourth coil 36, and the change in the oscillation frequency of the first coil 21 leads in phase by λ / 6 (= L / 3) from the change in the oscillation frequency of the second coil 26.

[0065] FIG. 11(c) shows the frequency change (Δf) per unit length for the oscillation frequency of the first coil 21, the oscillation frequency of the second coil 26, and the oscillation frequency of the fourth coil 36 shown in FIG. 11(b), that is, the differential processing of the graph shown in FIG. 11(b). In each waveform shown in FIG. 11(c), the part above the upper dashed line and the part below the lower dashed line are ranges where the frequency change (Δf) is large, and this region corresponds to the region between the peaks of each waveform shown in FIG. 11(b), and is a region where the position change (ΔD) can be detected with high accuracy (high resolution) from the oscillation frequency change (Δf). The waveforms of each oscillation frequency between these peaks are continuous in the moving direction of the moving body 13.

[0066] Therefore, also in this example, the position of the moving body 13 can be detected with high accuracy by selectively using the oscillation frequency whose changing waveform corresponds to between peaks among the oscillation frequency extracted from the first coil 21, the oscillation frequency extracted from the second coil 26, and the oscillation frequency extracted from the fourth coil 36. For ease of understanding, Fig. 11(b) and (c) show an example of the usage range of the oscillation frequency of the first coil 21, the usage range of the oscillation frequency of the second coil 26, and the usage range of the oscillation frequency of the fourth coil 36. In this example, only about 87% or more of the peak of Δf is used.

[0067] In the above example, the third coil 31, the first coil 21, and the second coil 26 are sequentially arranged coaxially from the upstream side to the downstream side in the moving direction (displacement direction) of the movable body 13, but the present invention is not limited to this embodiment, and may be arranged, for example, from the upstream side to the downstream side in the order of the first coil 21, the second coil 26, and the third coil 31, as shown in Fig. 12. Even in such an embodiment, the position of the movable body 13 can be detected with high accuracy. The same applies to the embodiment in which three or more detection units are provided, as shown in Fig. 11.

[0068] 4, 11 and 12, when detecting only the incremental position (relative displacement) and not the absolute position of the movable body 13, it is not necessary to provide the third detection unit 30, and it is sufficient to provide only the first detection unit 20 and the second detection unit 25. Even in such an embodiment, the incremental position (relative displacement) of the movable body 13 can be detected with high resolution and high accuracy.

[0069] In the position detection devices and the like shown in Fig. 4, Fig. 11 and Fig. 12, the movable body 13 may take the forms shown in Fig. 13 and Fig. 14. Fig. 13 shows a movable body 53 which replaces the movable body 13. Fig. 13(a) is a front cross-sectional view of the movable body 13, and Fig. 13(b) is a right side view of (a).

[0070] As shown in FIG. 13(a), the movable body 53 is composed of a bottomed, hollow cylinder 54b with one open end, a holding portion 54 consisting of an axis portion 54a formed on the left end face (the outer end face of the bottom) of this cylinder 54b in the figure so as to extend coaxially with the cylinder 54b, and detection portions 55a, 55b, 55c and 55d which are ring-shaped protrusions provided at predetermined intervals on the inner surface of the cylinder 54b.

[0071] As in the case of the moving body 13, there is no restriction on the material of the shaft portion 54a and the cylindrical body 54b, but from the viewpoint of realizing high measurement accuracy, it is preferable that they are made of stainless steel. Also, the detected parts 55a, 55b, 55c, and 55d only need to be conductive, and there are no other restrictions on the material, but preferred materials include copper and aluminum. Also, in FIG. 13, four detected parts 55a, 55b, 55c, and 55d are provided as an example, but this is not limited thereto, and the number of detected parts may be three or less (one or more), or five or more.

[0072] The width of the detection target parts 55a, 55b, 55c, and 55d is the same as the coil length of the first coil 21 and the second coil 26, and the distance between them is the same as the dimension L. The detection target parts 55a, 55b, 55c, and 55d can be formed by fitting a ring-shaped part into the cylindrical body 54b by hammering. Alternatively, they can be formed by fitting a hollow cylindrical element into the cylindrical body 54b and then cutting out a groove to become a recess. The inner diameters of the detection target parts 55a, 55b, 55c, and 55d are set to be as small as possible so that the first coil 21, the second coil 26, and the third coil 31 can pass through them without contacting them.

[0073] When this movable body 53 is moved in the direction indicated by the arrow, the third coil 31, the first coil 21, and the second coil 26 pass relatively through the detection portions 55a, 55b, 55c, and 55d, thereby extracting an oscillation frequency that is a sine wave from each of the coils 31, 21, and 26.

[0074] 14 shows a composite type moving body in which the moving body 13 and the moving body 53 are combined and connected to each other. In this example, the shaft 54a of the holding part 54 is integrated with the shaft 14 of the moving body 13, and the bottom of the cylindrical body 54b is penetrated by the shaft 14 and fixed to the shaft 14. The detection parts 15a, 15b, 15c, and 15d of the moving body 13 are located inside the cylindrical body 54b of the moving body 53, and are provided so that their respective positions match with the detection parts 55a, 55b, 55c, and 55d. The intervals between the detection parts 15a, 15b, 15c, and 15d and the detection parts 55a, 55b, 55c, and 55d are such that the third coil 31, the first coil 21, and the second coil 26 can pass through relatively.

[0075] When the moving body 60 is moved in the direction of the arrow, the third coil 31, the first coil 21, and the second coil 26 enter and pass through the gaps between the detection target parts 15a, 15b, 15c, and 15d and the detection target parts 55a, 55b, 55c, and 55d, respectively, thereby extracting an oscillation frequency as a sine wave from each of the coils 31, 21, and 26. In this embodiment, the detection target parts 15a, 15b, 15c, and 15d and the detection target parts 55a, 55b, 55c, and 55d sandwich the third coil 31, the first coil 21, and the second coil 26, so that the change in the oscillation frequency as a sine wave extracted from each of the coils 31, 21, and 26 can be increased, and more accurate position detection is possible.

[0076] In the above example, the first coil 21 of the first detection unit 20, the second coil 26 of the second detection unit 25, and the third coil 31 of the third detection unit are formed in a hollow cylindrical shape, but the shapes of the first coil 21, the second coil 26, and the third coil 31 are not limited to such hollow cylindrical shapes, and may be flat shapes as shown in Fig. 15. The same applies to the embodiment in which three or more detection units are provided as shown in Fig. 11.

[0077] The position detection device 100 shown in Fig. 15 differs from the above-described position detection device 1 in the configurations of the first detection unit 120, the second detection unit 125, the third detection unit 130, and the moving body 113. Therefore, in Fig. 15, the same components as those of the position detection device 1 are denoted by the same reference numerals.

[0078] 15, the position detection device 100 includes a third coil 131, a first coil 121, and a second coil 126, which are formed on a substrate 116 in a plane and aligned in a line along the direction of the arrow, which is the moving direction of the moving body 113. In this position detection device 100, the first detection section 120 is configured from the first coil 121 and a capacitor 122 connected between both ends 121a, 121b, and the second detection section 125 is configured from the second coil 126 and a capacitor 127 connected between both ends 126a, 126b. The third detection section 130 is configured from the third coil 131 and a capacitor 132 connected between both ends 131a, 131b.

[0079] Both ends 121a, 121b of the first coil 121, both ends 126a, 126b of the second coil 126, and both ends 131a, 131b of the third coil 131 are connected to the oscillation control / frequency converter 40 provided on the substrate 116. The coil lengths (widths in the direction indicated by the arrows) and arrangement intervals of the first coil 121, the second coil 126, and the third coil 131 are the same as those in the example of the position detection device 1.

[0080] As shown in Fig. 16, the movable body 113 is composed of a shaft portion 114 and a main body 115. The shaft portion 114 has a solid cylindrical shape, is connected to the probe 12 so as to be coaxial with the probe 12, and is supported by an appropriate support member so as to be movable in the direction along the axis. The main body 115 is comb-shaped when viewed from the front, in other words, has a rectangular wave-shaped contour, and has four protruding portions that protrude downward in Fig. 16, which are detection target portions 115a, 115b, 115c, and 115d in order from the right. The widths of the protruding portions 115a, 115b, 115c, and 115d in the direction indicated by the arrow, which is the movement direction (displacement direction), and the widths of the valleys between them are the same as those in the movable body 13 of the position detection device 1. In addition, the movable body 113 is disposed between the lower surfaces of its detection portions 115a, 115b, 115c, and 115d and the upper surface of the substrate 116, with a predetermined gap between them, and above the third coil 131, the first coil 121, and the second coil 126 which are aligned in a row. The movable body 113 is disposed so as to be displaceable in the direction indicated by the arrow.

[0081] The position detection device 100 having the above-mentioned configuration also exerts the same functions and effects as the position detection device 1 described above.

[0082] In the position detection device 100, the moving body 113 can take the form of a modified example shown in FIG.

[0083] The movable body 143 shown in FIG. 17(a) is composed of an axis portion 144 and a main body 145. The axis portion 144 has a solid cylindrical shape, is connected to the probe 12 so as to be coaxial with the probe 12, and is supported by an appropriate support member so as to be displaceable in the direction along the axis. The main body 145 has a rectangular shape in a plan view that is elongated along the displacement direction (arrow direction), and rectangular conductors are arranged in a row along the displacement direction on the surface facing the third coil 131, the first coil 121, and the second coil 126. The conductors are detected parts 146a, 146b, 146c, and 146d in order from the right. The widths of the detected parts 146a, 146b, 146c, and 146d in the displacement direction (arrow direction) and the intervals therebetween are the same as those in the example of the movable body 13 of the position detection device 1.

[0084] 17(b) is composed of an axis 154 and a body 155. The axis 154 has a solid cylindrical shape, is connected to the probe 12 so as to be coaxial with the probe 12, and is supported by an appropriate support member so as to be displaceable in the direction along the axis. The body 155 is made of a conductor and has a rectangular shape in a plan view that is elongated along the displacement direction (arrow direction). The body 155 has four rectangular punched spaces formed along its longitudinal direction, and the remaining conductor parts are detection targets 156a, 156b, 156c, and 156d in order from the right. The widths of the detection targets 156a, 156b, 156c, and 156d in the displacement direction (arrow direction) and the intervals therebetween are the same as those in the example of the moving body 13 of the position detection device 1.

[0085] As a modification of the arrangement of the third coil 131, the first coil 121 and the second coil 126 on the substrate 116 shown in FIG. 15, the arrangement shown in FIG. 18 can be exemplified.

[0086] In the example shown in Fig. 18(a) and (b), the third coil 131, the first coil 121, and the second coil 126 are provided along the displacement direction (arrow direction) of the moving body 113, and the first coil 121 and the second coil 126 are arranged in parallel in a direction perpendicular to the displacement direction (arrow direction). The second coil 126 is shifted by L / 2 in the displacement direction (arrow direction) of the moving body 113 with respect to the first coil 121. In this example, the interval between the second coil 126 and the first coil 121 in the perpendicular direction is set arbitrarily. When n coils are provided as the relative displacement detection unit, the shift distance between the coils in the displacement direction (arrow direction) of the moving body 113 is generalized to (L±L / n).

[0087] The third coil 131 can be disposed inside the first coil 121 and the second coil 126 in a direction perpendicular to the displacement direction as shown in (a), or can be disposed outside the second coil 126 in a direction perpendicular to the displacement direction as shown in (b), and can also be disposed outside the first coil 121 in a direction perpendicular to the displacement direction, although not shown. In these cases, the width of the moving body 131 in a direction perpendicular to the displacement direction, in other words, the width of the detection target parts 115a, 115b, 115c, and 115d is set to a width that overlaps the third coil 131, the first coil 121, and the second coil 126 in the vertical direction. The same applies to the moving bodies 143 and 153 shown in FIG. 17.

[0088] In the above example, the position calculation unit 41 and the data storage unit 42 are configured to be provided inside the case 11 as the measurement unit 10, but the present invention is not limited to this configuration, and the position calculation unit 41 and the data storage unit 42 may be configured to face away from the case 11. In this case, the position calculation unit 41 and the oscillation control / frequency converter 40 are connected by a communication means, and oscillation frequency data is transmitted from the oscillation control / frequency converter 40 to the position calculation unit 41. In this case, the display unit 50 may also be provided separately from the measurement unit 10, or the display unit 10 may be formed integrally with the position calculation unit 41 and the data storage unit 42.

[0089] Alternatively, the measurement unit 10 and the display unit 50 may be provided separately, and the position calculation unit 41 and the display unit 10 may be connected by a communication means. In this case, the position calculation unit 41 transmits position data as a measurement value to the display unit 50, and the measurement value is displayed on the display unit 50.

[0090] It should be noted that the above-described embodiment is illustrative in all respects and is not restrictive. Modifications and changes are possible for those skilled in the art. The scope of the present invention is indicated by the claims, not the above-described embodiment. Furthermore, the scope of the present invention includes modifications from the embodiments within the scope of the claims and the equivalent scope. [Explanation of symbols]

[0091] 1 Position detection device 10 Measuring part 11 Cases 12 Probe 13 Mobile 14 Shaft 15 Detected part 15a 1st detected part 15b Second detection part 15c 3rd detected part 15d Fourth detection part 20 First detection unit 21 Wound coil 22 Capacitor 25 Second detection section 26 Wound coil 27 Capacitor 30 Third detection section 31 Wound coil 32 Capacitor 40 Oscillation control / frequency converter 41 Position calculation section 42 Data storage unit 50 Display

Claims

1. a moving body having an elongated shape, movable along its longitudinal direction, and having a plurality of conductive detection targets provided along the longitudinal direction; a plurality of relative displacement detection units arranged along a moving direction of the moving body and arranged to be opposed to each of the detection targets of the moving body at a predetermined interval, for detecting a relative displacement of the moving body; a position calculation unit that processes each output signal from the relative displacement detection unit to calculate a displacement of the moving object, Each of the relative displacement detection sections is a position detection device including a winding coil for forming an LC circuit and a capacitor connected between both ends of the winding coil.

2. an absolute position detection unit that is provided on one side or the other side of the relative displacement detection unit in the moving direction of the moving body so as to be able to face each of the detection targets of the moving body at the predetermined interval, and detects an absolute position of the moving body; the absolute position detection unit includes a winding coil for forming an LC circuit, the winding coil having a length longer than that of the winding coil of the relative displacement detection unit, and a capacitor connected between both ends of the winding coil; 2. The position detection device according to claim 1, wherein the position calculation section is configured to process output signals from the relative displacement detection section and the absolute position detection section to detect the position of the moving body.

3. The relative displacement detection unit is provided in a number of n, each of the winding coils has the same length, and each winding coil has a length L and is arranged at an interval of (L±L / n) from each other, 3. The position detection device according to claim 1, wherein each of the detected portions of the moving body has a width in the longitudinal direction that is the same as the length of the winding coil of the relative displacement detection portion, and is arranged at a distance corresponding to the length of the winding coil of the relative displacement detection portion.

4. Each of the winding coils has a hollow cylindrical shape, 3. The position detection device according to claim 1, wherein the movable body has an axial shape, and the detected portion has a cylindrical shape and is provided so as to be insertable into each of the winding coils.

5. 3. The position detection device according to claim 1, wherein each of said winding coils is a planar coil.

6. a moving body having an elongated shape, movable along its longitudinal direction, and having a plurality of conductive detection targets provided along the longitudinal direction; a plurality of relative displacement detection units arranged to be opposed to each of the detection target portions of the moving body at a predetermined interval, arranged side by side in a direction perpendicular to the moving direction of the moving body, and arranged to move back and forth relative to each other along the moving direction, for detecting a relative displacement of the moving body; a position calculation unit that processes each output signal from the relative displacement detection unit to calculate a displacement of the moving object, Each of the relative displacement detection units is a position detection device including a wound coil, which is a planar coil for forming an LC circuit, and a capacitor connected between both ends of the wound coil.

7. an absolute position detection unit that is provided on one side or the other side of the relative displacement detection unit in the moving direction of the moving body, so as to be able to face each of the detection targets of the moving body at the predetermined interval, and detects an absolute position of the moving body; the absolute position detection unit includes a winding coil, which is a planar coil for forming an LC circuit, and a capacitor connected between both ends of the winding coil, and the winding coil of the absolute position detection unit has a length longer than that of the winding coil of the relative displacement detection unit; 7. The position detection device according to claim 6, wherein the position calculation section is configured to process output signals from the relative displacement detection section and the absolute position detection section to detect the position of the moving body.

8. the number of the relative displacement detection units is n, each of the winding coils has the same length, and each winding coil is disposed in front of or behind the other in the moving direction by a distance corresponding to (L±L / n), where L is the length of the winding coil; 8. The position detection device according to claim 6, wherein the width in the longitudinal direction of each of the detection target portions of the movable body is the same as the length of the winding coil of the relative displacement detection portion.

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