Displacement detection device, displacement detection method, and fluid pressure actuator

Abstract

To provide a displacement detection device or the like capable of easily and accurately detecting the displacement of a shaft member with respect to a stationary part, and expected to be used, for example, in an application requiring positioning at a level of several nanometers.SOLUTION: The first displacement detecting device 25 includes the sleeve 10, the outputting shaft 5, a plurality of reflecting portions (first protruding portions) 2a disposed on the outer peripheral surface of the outputting shaft 5 at intervals in the axial direction, first light emitting portions 2a and 11b that are stationary with respect to the sleeve 10 and emit light toward the reflecting portions 11a, first light receiving portions 2a and 11b that receive at least part of the light emitted from the first light emitting portions 14a and 14b and reaching an axial range of the outputting shaft 5 in which the reflecting portions are provided, and an axial displacement detecting portion that detects axial displacement of the outputting shaft 5 with respect to the sleeve 10 based on the light received by the first light receiving portions and. 14a 11a 14b.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a displacement detection device and a displacement detection method for detecting the displacement of a shaft member relative to a stationary part, and also to a fluid pressure actuator. [Background technology]

[0002] A conventional fluid pressure actuator is described in Patent Document 1. This fluid pressure actuator includes a sleeve, an advance / retract drive unit, an output shaft rotation drive unit, a spring body, a rotation angle detection sensor, an axial displacement sensor, and a control device. One end of the spring body is fixed to the output shaft rotation drive unit, and the other end of the spring body is fixed to the output shaft. The rotation angle detection sensor detects the rotation angle of the output shaft relative to the sleeve, and the axial displacement sensor detects the axial displacement of the output shaft relative to the sleeve.

[0003] The output shaft has a flange portion, and an end face of the flange portion on a first axial side defines a part of the inner surface of the first chamber, and an end face of the flange portion on a second axial side defines a part of the inner surface of the second chamber. The control device drives the advance / retreat drive portion based on a signal from the axial displacement sensor, thereby controlling the air pressure difference between the first chamber and the second chamber, and thereby controlling the axial displacement of the output shaft relative to the sleeve.

[0004] In addition, the control device drives the output shaft rotation drive unit based on a signal from the rotation angle detection sensor, thereby controlling the rotational power transmitted from the output shaft rotation drive unit to the output shaft via the spring body, and controlling the rotational displacement of the output shaft relative to the sleeve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-126493 Summary of the Invention [Problem to be solved by the invention]

[0006] It is known that EUV (Extreme Ultraviolet) exposure technology can be used to form circuit patterns composed of wiring and elements with widths on the order of a few nanometers, enabling the formation of extremely high-performance semiconductor chips. Technology is also known for stacking multiple layers of substrates to form multiple semiconductor chips. In this context, if the relative positions of multiple stacked substrates could be controlled to the order of a few nanometers, the development of state-of-the-art semiconductor chip manufacturing equipment using multilayer substrates would advance.

[0007] Therefore, the object of the present disclosure is to provide a displacement detection device and a displacement detection method for detecting the displacement of an axial member relative to a stationary part, which can easily detect the displacement of an axial member relative to a stationary part accurately, can be expected to be used in applications requiring positioning at the level of several nanometers, and can easily detect the displacement of an axial member relative to a stationary part at the level of several nanometers.

[0008] Specifically, in a first example, the object of the present disclosure is to provide a displacement detection device and a displacement detection method for detecting axial displacement of an axial member relative to a stationary part, which can easily detect axial displacement of an axial member relative to a stationary part accurately, can be expected to be used in applications requiring axial positioning at the level of a few nanometers, and can easily detect axial displacement of the axial member relative to the stationary part at the level of a few nanometers.

[0009] In addition, in a second example, an object of the present disclosure is to provide a displacement detection device and a displacement detection method for detecting circumferential displacement of an axial member relative to a stationary part, which can easily detect circumferential displacement of an axial member relative to a stationary part accurately, can be expected to be used in applications requiring circumferential positioning at the level of a few nanometers, and can easily detect circumferential displacement of an axial member relative to a stationary part at the level of a few nanometers.

[0010] In addition, in a third example, an object of the present disclosure is to provide a displacement detection device and a displacement detection method for detecting the displacement of a shaft member relative to a stationary part, which can easily detect both the axial displacement and the circumferential displacement of the shaft member relative to the stationary part accurately, and which can be expected to be used in applications requiring, for example, axial positioning at the level of a few nanometers and circumferential positioning at the level of a few nanometers, and which can easily detect both the axial displacement of the shaft member relative to the stationary part at the level of a few nanometers and the circumferential displacement of the shaft member relative to the stationary part at the level of a few nanometers.

[0011] Another object of the present disclosure is to provide a fluid pressure actuator that can easily and accurately detect the axial displacement and rotational displacement of the shaft member relative to the stationary part, and that can easily control, for example, the axial displacement of the shaft member relative to the stationary part at the level of several nanometers and the rotational displacement of the shaft member relative to the stationary part at the level of several nanometers. [Means for solving the problem]

[0012] In order to solve the above problems, the displacement detection device of the present disclosure includes a stationary portion, a shaft member, a shaft member advance / retreat drive portion that enables axial displacement of the shaft member relative to the stationary portion, a plurality of first protrusions arranged at intervals in the axial direction on the outer peripheral surface of the shaft member, a first light-emitting portion that is stationary with respect to the stationary portion and emits light toward the first protrusions, a first light-receiving portion that receives at least a portion of the light that is emitted from the first light-emitting portion and reaches the axial range of the shaft member in which the first protrusions are provided, and an axial displacement detection portion that detects axial displacement of the shaft member relative to the stationary portion based on the light received by the first light-receiving portion.

[0013] In this specification, the protrusions may be provided so as to protrude radially outward from an outer peripheral surface portion where no protrusions are present, or may be provided between adjacent grooves by providing a plurality of grooves on the outer peripheral surface.

[0014] As described in JP 2022-66437 A, an optical encoder is known that uses an optical scale with slits (gradations) engraved at regular intervals, which is a part that switches between transmitting / blocking or reflecting / non-reflecting light.The optical encoder detects the distance traveled by converting light emitted from a light-emitting part into a regular light signal using the slits and reading the light signal with a light-receiving element.

[0015] In the optical scale of this optical encoder, reflective sections that reflect light in the longitudinal direction and transmissive sections are alternately provided on a band-shaped, flat scale substrate. This optical scale is used for position control of a linear axis. Another known optical scale for optical encoders is a circular "disk (code wheel)" that is used for rotational direction control. In this circular optical scale, reflective sections that reflect light in the circumferential direction and transmissive sections are alternately provided on the disk.

[0016] On the other hand, at the time of filing, there are no mechanisms that have a shaft member that moves axially relative to a stationary part, and in which the optical scale of an optical encoder is provided on the outer circumferential surface of the shaft member. This is because it is believed that if the optical scale of an optical encoder is provided on something other than a plate member, it will not be possible to accurately detect the axial displacement of the moving part relative to the stationary part.

[0017] However, the applicant of the present application discovered for the first time, through conducting numerous tests over a long period of time, that even if an optical scale is provided on the outer surface of the shaft member, for example, on the outer surface of the shaft member that is composed of a curved surface, it is possible to accurately detect the displacement of the shaft member relative to the stationary part by emitting light from an emitting unit installed in the stationary part to the optical scale to create an optical signal, and then reading that optical signal with a photodetector.

[0018] The displacement detection device described above includes a plurality of first ridges arranged at intervals in the axial direction on the outer peripheral surface of the shaft member, a first light-emitting unit that is stationary with respect to the stationary unit and emits light toward the first ridges, a first light-receiving unit that receives at least a portion of the light that is emitted from the first light-emitting unit and reaches the axial range of the shaft member where the first ridges are provided, and an axial displacement detection unit that detects axial displacement of the shaft member relative to the stationary unit based on the light received by the first light-receiving unit. The displacement detection device described above can accurately detect axial displacement of the shaft member relative to the stationary unit, and can easily detect axial displacement of the shaft member relative to the stationary unit on the order of several nanometers, for example.

[0019] Furthermore, the above-mentioned displacement detection device comprising the first protrusion portion, first light-emitting portion, and first light-receiving portion may further comprise a shaft member rotation drive portion that enables rotational displacement of the shaft member relative to the stationary portion; a plurality of second protrusion portions arranged at intervals in the circumferential direction on the outer peripheral surface of the shaft member; a second light-emitting portion that is stationary with respect to the stationary portion and emits light toward the second protrusion portions; a second light-receiving portion that receives at least a portion of the light that is emitted from the second light-emitting portion and reaches the circumferential range of the shaft member in which the second protrusion portions are provided; and a circumferential displacement detection portion that detects circumferential displacement of the shaft member relative to the stationary portion based on the light received by the second light-receiving portion.

[0020] With this configuration, in addition to accurately detecting axial displacement of the shaft member relative to the stationary portion, it is also possible to accurately detect circumferential displacement of the shaft member relative to the stationary portion. For example, in addition to detecting axial displacement of the shaft member relative to the stationary portion at the level of a few nanometers, it is also easy to detect circumferential displacement of the shaft member relative to the stationary portion at the level of a few nanometers.

[0021] Furthermore, a displacement detection device according to another aspect of the present disclosure includes a stationary portion, a shaft member, a shaft member rotation drive portion that enables rotational displacement of the shaft member relative to the stationary portion, a plurality of ridge portions arranged at intervals in the circumferential direction on the outer peripheral surface of the shaft member, a light emitting portion that is stationary with respect to the stationary portion and emits light toward the ridge portions, a light receiving portion that receives at least a portion of the light that is emitted from the light emitting portion and reaches the circumferential range of the shaft member in which the ridge portions are provided, and a circumferential displacement detection portion that detects circumferential displacement of the shaft member relative to the stationary portion based on the light received by the light receiving portion.

[0022] According to the present disclosure, circumferential displacement of the shaft member relative to the stationary portion can be accurately detected, and for example, it is easy to detect circumferential displacement of the shaft member relative to the stationary portion at the level of several nanometers.

[0023] In addition, the displacement detection method of the present disclosure includes the steps of irradiating light from a first light-emitting unit that is stationary with respect to a stationary unit onto a first protrusion portion of an axial member that is movable axially relative to the stationary unit and has a plurality of first protrusion portions arranged on its outer surface at intervals in the axial direction, and detecting axial displacement of the axial member with respect to the stationary unit based on at least a portion of the light emitted from the first light-emitting unit that reaches the axial range of the axial member in which the first protrusion portions are provided.

[0024] According to the present disclosure, axial displacement of the shaft member relative to the stationary part can be accurately detected, and for example, axial displacement of the shaft member relative to the stationary part at the level of several nanometers can easily be detected.

[0025] Furthermore, the above-disclosed displacement detection method may further include a step in which the shaft member is movable circumferentially relative to the stationary portion and has a plurality of second protrusions arranged at intervals circumferentially on the outer circumferential surface, and the step of irradiating light onto the second protrusions from a second light-emitting portion that is stationary relative to the stationary portion, and a step of detecting circumferential displacement of the shaft member relative to the stationary portion based on at least a portion of the light that is emitted from the second light-emitting portion and reaches the circumferential range of the shaft member in which the second protrusions are provided.

[0026] With this configuration, in addition to accurately detecting axial displacement of the shaft member relative to the stationary portion, it is also possible to accurately detect circumferential displacement of the shaft member relative to the stationary portion. For example, in addition to detecting axial displacement of the shaft member relative to the stationary portion at the level of a few nanometers, it is also easy to detect circumferential displacement of the shaft member relative to the stationary portion at the level of a few nanometers.

[0027] Furthermore, a displacement detection method according to another aspect of the present disclosure may include the steps of irradiating light from a light-emitting unit that is stationary with respect to a stationary unit onto a protrusion of a shaft member that is movable circumferentially relative to the stationary unit and has a plurality of protrusions arranged on its outer surface at intervals in the circumferential direction, and detecting circumferential displacement of the shaft member with respect to the stationary unit based on at least a portion of the light that is emitted from the light-emitting unit and reaches the circumferential range of the shaft member in which the protrusions are provided.

[0028] According to the present disclosure, circumferential displacement of the shaft member relative to the stationary portion can be accurately detected, and for example, it is easy to detect circumferential displacement of the shaft member relative to the stationary portion at the level of several nanometers.

[0029] The fluid pressure actuator of the present disclosure also includes an output shaft having at least one first pressure-receiving surface, a plurality of first ridge portions arranged on an outer peripheral surface at intervals in the axial direction, and a plurality of second ridge portions arranged on the outer peripheral surface at intervals in the circumferential direction, a sleeve having an inner peripheral surface portion that supports the output shaft so as to be movable in the axial direction, and a second pressure-receiving surface that, in cooperation with the first pressure-receiving surface, defines at least a part of a pressure chamber, an advance / retract drive unit that varies the volume of the pressure chamber by changing the amount of fluid supplied to the pressure chamber, thereby advancing and retracting the output shaft in the axial direction relative to the sleeve, a rotating unit that is arranged radially outward of the output shaft so as to be rotatable approximately coaxially with the output shaft, and a rotary unit that is arranged radially outward of the output shaft so as to be expandable and contractible in the axial direction so as to be approximately coaxial with the output shaft, the rotary unit having one end fixed to the output shaft and another end fixed to the rotating unit, a first sensor that is stationary with respect to the sleeve and includes a first light-emitting unit that emits light toward the first protrusion portion and a first light-receiving unit that receives at least a portion of the light that is emitted from the first light-emitting unit and reaches the axial range of the shaft member in which the first protrusion portion is provided; an axial displacement detection unit that detects axial displacement of the shaft member with respect to the stationary portion based on the light received by the first light-receiving unit; a second sensor that is stationary with respect to the sleeve and includes a second light-emitting unit that emits light toward the second protrusion portion and a second light-receiving unit that receives at least a portion of the light that is emitted from the second light-emitting unit and reaches the circumferential range of the shaft member in which the second protrusion portion is provided; and a circumferential displacement detection unit that detects circumferential displacement of the shaft member with respect to the stationary portion based on the light received by the second light-receiving unit.

[0030] According to the fluid pressure actuator of the present disclosure, in addition to accurately detecting axial displacement of the shaft member relative to the stationary portion, it is also possible to accurately detect circumferential displacement of the shaft member relative to the stationary portion. For example, in addition to detecting axial displacement of the shaft member relative to the stationary portion at the level of a few nanometers, it is also possible to easily detect circumferential displacement of the shaft member relative to the stationary portion at the level of a few nanometers. [Effects of the Invention]

[0031] According to the present disclosure, it is possible to realize a displacement detection device and a displacement detection method for detecting the displacement of a shaft member relative to a stationary part, which can easily detect the displacement of a shaft member relative to a stationary part, and which can be expected to be used in applications requiring positioning at the level of several nanometers, for example, and can easily detect the displacement of the shaft member relative to the stationary part at the level of several nanometers.Furthermore, according to the present disclosure, it is possible to realize a fluid pressure actuator that can easily detect the axial displacement and rotational displacement of the shaft member relative to the stationary part, and which can easily control, for example, the axial displacement of the shaft member relative to the stationary part at the level of several nanometers and the rotational displacement of the shaft member relative to the stationary part at the level of several nanometers. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a schematic axial cross-sectional view of a fluid pressure actuator according to a first embodiment of the present disclosure. [Figure 2] 2 is a part of the schematic cross-sectional view taken along line AA in FIG. 1, and is a schematic cross-sectional view for explaining the operation of the servo valve to rotate the rotating part. FIG. [Figure 3] FIG. [Figure 4] 1A and 1B are diagrams illustrating the structure of an axial displacement sensor, in which (a) is a schematic axial cross-sectional view of the axial displacement sensor, and (b) is a plan view of a portion of a circular ring member as viewed from the radially outer side. [Figure 5] 3A and 3B are diagrams illustrating the structure of a rotation angle detection sensor. [Figure 6] FIG. 4 is a plan view of a portion of the annular member as viewed from the radially outer side. [Figure 7] FIG. 3 is a schematic cross-sectional view of a servo valve according to a modified example, corresponding to FIG. 2. [Figure 8] FIG. 10 is a perspective view of a spring body according to a modified example. [Figure 9] FIG. 10 is a schematic cross-sectional view in the axial direction of a fluid pressure actuator according to a second embodiment of the present disclosure. [Figure 10] FIG. 10 is a plan view of a circular member that constitutes a part of the output shaft of a fluid pressure actuator of a second embodiment, as viewed from the outside in the radial direction. [Figure 11]10 is a cross-sectional view of the output shaft of the fluid pressure actuator of the second embodiment when cut along a plane that passes through the axial center position of the sensor main body and includes the radial direction. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that, when multiple embodiments or variations are included below, it is assumed from the outset that new embodiments can be constructed by appropriately combining their characteristic features. In the following examples, the same components are denoted by the same reference numerals in the drawings, and redundant explanations will be omitted. The drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component between different drawings do not necessarily match.

[0034] In the following, a pneumatic pressure actuator that uses gas will be described as a fluid pressure actuator, but a hydraulic actuator or a water pressure actuator that uses a liquid other than gas may also be used. The gas used as a fluid may be ordinary air, dry air, an inert gas such as nitrogen or argon, or another gas.

[0035] In the following description, when an axial direction is mentioned, the axial direction refers to the axial direction of the shaft member (output shaft) 5, 205, and when a circumferential direction is mentioned, the circumferential direction refers to the circumferential direction of the shaft member (output shaft) 5, 205. Furthermore, in the following description, when a radial direction is mentioned, the radial direction refers to the radial direction of the shaft member (output shaft) 5, 205. In the drawings, the X direction indicates the axial direction of the output shaft (shaft member) 5, 205, the θ direction indicates the circumferential direction of the output shaft 5, 205, and the R direction indicates the radial direction of the output shaft 5, 205. The X direction, the θ direction, and the R direction are perpendicular to one another. Furthermore, in the following drawings, drawings that include first protrusions and second protrusions are schematic diagrams. For example, the number of first protrusions and second protrusions is generally much greater than the number shown in the following drawings.

[0036] In the following description, in the fluid pressure actuator 1, 205, the axial side of the output shaft 5, 205 where materials or electronic components (for example, a substrate or a chip) are fixed will be referred to as the axial front side, and the opposite side will be referred to as the axial rear side. Furthermore, among the components described below, components that are not recited in the independent claims that represent the superordinate concept are optional components and are not essential components.

[0037] (First embodiment) Fig. 1 is a schematic axial cross-sectional view of a fluid pressure actuator 1 according to a first embodiment of the present disclosure. This fluid pressure actuator 1 is used, for example, in the manufacture of semiconductor chips using multilayer substrates to position a second substrate relative to a first substrate with precision on the order of a few nanometers. As shown in Fig. 1, the fluid pressure actuator 1 includes an output shaft 5 constituting a shaft member, a sleeve 10 as an example of a stationary portion, an advance / retract drive unit 30 as an example of a shaft member advance / retract drive unit, a rotation drive unit 50 as an example of a shaft member rotation drive unit, a spring body 70, an axial displacement sensor 20 as a first sensor, and a rotation angle detection sensor 40 as a second sensor.

[0038] The output shaft 5 is an integral shaft member and includes a cylindrical portion 5a and a shaft portion 5b. The output shaft 5 is made of, for example, metal or hard resin. The spring body 70 is disposed radially outward of the shaft portion 5b, the axial displacement sensor 20 detects the axial displacement of the shaft portion 5b relative to the sleeve 10, and the rotation angle detection sensor 40 detects the rotation angle (circumferential displacement) of the shaft portion 5b relative to the sleeve 10. The output shaft 5 may be molded as an integral unit, or may be formed by bonding multiple portions together using an adhesive, welding, screw fastening, caulking, press fitting, or the like to prevent them from moving relative to each other.

[0039] The shaft portion 5b has, for example, a cylindrical shape with a circular cross section. The output shaft 5 further has a flange portion 5c. The flange portion 5c is an annular protrusion that protrudes radially from the cylindrical portion 5a, and the radial tip surface of the flange portion 5c forms a cylindrical outer peripheral surface 7. Annular end surfaces 8a and 8b on both axial sides of the flange portion 5c are first pressure-receiving surfaces that receive the pressure of air supplied from the advance / retreat drive unit 30.

[0040] The sleeve 10 has a first inner peripheral surface portion 10a that supports the outer peripheral portion of the cylindrical portion 5a so that it can slide in the axial direction, and a second inner peripheral surface portion 10b that supports the cylindrical outer peripheral surface 7 of the flange portion 5c so that it can slide in the axial direction. The second inner peripheral surface portion 10b is connected to the first inner peripheral surface portion 10a via annular end faces 10c and 10d, and the axial length of the second inner peripheral surface portion 10b is longer than the axial length of the flange portion 5c. The annular end faces 10c and 10d and the annular end faces 8a and 8b of the flange portion 5c preferably extend radially in approximately parallel relation. The annular end faces 10c and 10d of the sleeve 10 have approximately the same radial dimension as the end faces 8a and 8b on both axial sides of the flange portion 5c and axially face the end faces 8a and 8b of the flange portion 5c. The annular end surfaces 10c and 10d of the sleeve 10 are second pressure receiving surfaces, and define parts of the pressure chambers 9a and 9b into which air from the advance / retract drive unit 30 is filled.

[0041] The forward / backward drive unit 30 includes a servo valve 31 and a first passage 32a and a second passage 32b provided in the sleeve 10. The first passage 32a connects a first discharge / suction port (not shown) of the servo valve 31 to an axially front end of the second inner circumferential surface portion 10b, and the second passage 32b connects a second discharge / suction port (not shown) of the servo valve 31 to an axially rear end of the second inner circumferential surface portion 10b. Because the axial length of the second inner circumferential surface portion 10b is longer than the axial length of the flange portion 5c, a space is formed on at least one axial side of the flange portion 5c, surrounded by the second inner circumferential surface portion 10b of the sleeve 10, the annular end faces 10c and 10d of the sleeve 10, the cylindrical portion 5a, and the axially opposite end faces 8a and 8b of the flange portion 5c. This space constitutes pressure chambers 9a and 9b.

[0042] The advancing / retreating drive unit 30 advances and retreats the output shaft 5 as follows. More specifically, the servo valve 31 of the advancing / retreating drive unit 30 operates so that when the first discharge / suction port discharges air, the second discharge / suction port sucks in air, and conversely, when the first discharge / suction port sucks in air, the second discharge / suction port discharges air. As a result, when air is supplied from the first passage 32a to the axially front end of the second inner circumferential surface portion 10b, the volume of the first pressure chamber 9a, which is located axially forward of the flange portion 5c, gradually increases, causing the output shaft 5 to retreat rearward. Conversely, when air is supplied from the second passage 32b to the axially rear end of the second inner circumferential surface portion 10b, the volume of the second pressure chamber 9b, which is located axially rearward of the flange portion 5c, gradually increases, causing the output shaft 5 to advance forward.

[0043] The fluid pressure actuator 1 also has a third passage 32c branching from the first passage 32a and opening at a portion of the first inner circumferential surface portion 10a that is axially forward of the first pressure chamber 9a, a fourth passage 32d having an opening positioned axially rearward of the opening of the third passage 32c on the first inner circumferential surface portion 10a side, and connecting the first inner circumferential surface portion 10a to the outside, a fifth passage 32e branching from the second passage 32b and opening at a portion of the first inner circumferential surface portion 10a that is axially rearward of the second pressure chamber 9b, and a sixth passage 32f having an opening positioned axially forward of the opening of the fifth passage 32e on the first inner circumferential surface portion 10a side, and connecting the first inner circumferential surface portion 10a to the outside.

[0044] When the first discharge / suction port discharges air and the second discharge / suction port sucks air, the air flows in the direction indicated by arrow a1 through the third passage 32c, between the first inner circumferential surface portion 10a located axially further forward than the first pressure chamber 9a and the cylindrical portion 5a, and the fourth passage 32d, in that order, and also flows in the direction indicated by arrow a2 through the sixth passage 32f, between the first inner circumferential surface portion 10a located axially further rearward than the second pressure chamber 9b and the cylindrical portion 5a, and the fifth passage 32e, in that order. Therefore, a hydrostatic bearing can be generated between the first inner circumferential surface portion 10a and the cylindrical portion 5a both axially further forward than the first pressure chamber 9a and axially further rearward than the second pressure chamber 9b.

[0045] Conversely, when the first discharge suction port draws in air and the second discharge suction port discharges air, air flows in the direction indicated by arrow b1 through the fourth passage 32d, between the first inner circumferential surface portion 10a (axially forward of the first pressure chamber 9a) and the cylindrical portion 5a, and then through the third passage 32c. Air also flows in the direction indicated by arrow b2 through the fifth passage 32e, between the first inner circumferential surface portion 10a (axially rearward of the second pressure chamber 9b) and the cylindrical portion 5a, and then through the sixth passage 32f. Therefore, even in this case, a hydrostatic bearing can be generated between the first inner circumferential surface portion 10a and the cylindrical portion 5a both axially forward of the first pressure chamber 9a and axially rearward of the second pressure chamber 9b. Therefore, when the output shaft 5 moves axially, the hydrostatic bearing can support the cylindrical portion 5a so that it can move back and forth relative to the first inner circumferential surface portion 10a without contacting the first inner circumferential surface portion 10a.

[0046] In the first embodiment, when the output shaft 5 moves back and forth in the axial direction, the cylindrical portion 5a is supported by a hydrostatic bearing so that it can move back and forth freely against the first inner surface portion 10a. However, when the output shaft 5 moves back and forth in the axial direction, the cylindrical portion 5a may also be supported by a sliding bearing so that it can move back and forth freely against the first inner surface portion 10a, or the cylindrical portion 5a may not need to be supported by a bearing against the first inner surface portion 10a when the output shaft 5 moves back and forth in the axial direction.

[0047] The internal chamber R of the cylindrical portion 5a communicates with a vacuum pump (not shown), for example, via a passage (not shown). In this case, by performing a vacuum using the vacuum pump, an opening 5d provided in the front end surface 5d of the output shaft 5 and communicating with the internal chamber R sucks in an object such as a substrate, thereby fixing the object to the front end surface 5d. Furthermore, by stopping the vacuum pump from performing a vacuum, the object can be removed from the front end surface 5d. Note that although the case where the output shaft 5 includes the cylindrical portion 5a has been described, the output shaft does not necessarily have to include a cylindrical portion.

[0048] The rotary drive unit 50 has a servo valve 51 that constitutes a rotary actuator. Fig. 2 is a part of the schematic cross-sectional view taken along line AA in Fig. 1, and is a schematic cross-sectional view for explaining the operation of the servo valve 51 to rotate the rotating unit 53. As shown in Fig. 2, the servo valve 51 has a cylindrical case 52 and a cylindrical rotating unit 53. The axial center of the cylindrical case 52 substantially coincides with the axial center of the cylindrical rotating unit 53, and a cylindrical inner peripheral surface 52a of the case 52 faces a cylindrical outer peripheral surface 53a of the rotating unit 53 in the radial direction, with a gap therebetween.

[0049] The servo valve 51 further has a protrusion 54 that protrudes radially inward from the cylindrical inner circumferential surface 52a and faces the cylindrical outer circumferential surface 53a of the rotating part 53 with a small gap in between, and a vane 55 that protrudes radially inward from the cylindrical outer circumferential surface 53a of the rotating part 53 and faces the cylindrical inner circumferential surface 52a with a small gap in between. With this configuration, two pressure chambers 56a, 56b are formed within the case 52, with the protrusion 54 and the vane 55 as boundaries. The servo valve 51 also has discharge and suction ports 57a, 57b that discharge or suction air. The discharge and suction ports 57a, 57b are provided at the base of the protrusion 54 on both circumferential sides in the wall 58 of the case 52 that is approximately perpendicular to the axial direction.

[0050] By discharging air from discharge and suction port 57a located on the right side of protrusion 54 in the plane of Fig. 2 and sucking air from discharge and suction port 57b located on the left side of protrusion 54, vane 55 can be rotated clockwise in the plane of Fig. 2, and as a result, rotating part 53 can be rotated clockwise in the plane of Fig. 2. Conversely, by discharging air from discharge and suction port 57b and sucking air from discharge and suction port 57a, vane 55 can be rotated counterclockwise in the plane of Fig. 2, and as a result, rotating part 53 can be rotated counterclockwise in the plane of Fig. 2.

[0051] Referring again to FIG. 1 , the rotating portion 53 is located radially outward of the shaft portion 5b and is disposed substantially coaxially with the shaft portion 5b. The spring body 70 has a front end portion 71, a rear end portion 72, and a spring portion 73. The front end portion 71 is pinned to the axially rear end face of the annular flange portion 5f of the output shaft 5 by a plurality of pins (not shown) spaced apart in the circumferential direction. The rear end portion 72 is screwed to the axially front end face of the annular flange portion 65 provided on the axially front side of the rotating portion 53 by a plurality of bolts (not shown) spaced apart in the circumferential direction. The spring portion 73 is disposed between the front end portion 71 and the rear end portion 72 and connects the front end portion 71 and the rear end portion 72. Both axial ends of the spring body 70 are fixed to the output shaft 5 and the rotating portion 53 by pinning or bolting. However, both axial ends of the spring body 70 may be fixed to the output shaft or the rotating part using any structure, and may be fixed to the output shaft or the rotating part using screws, pins, adhesive bonding, welding, press fitting, crimping, etc.

[0052] The spring body 70 is made of a vibration-damping metal, such as a graphite cast iron, aluminum, or zinc alloy. When the spring body 70 is made of a vibration-damping alloy, the spring body 70 may be made of any of the following types: composite, ferromagnetic, dislocation, or twin crystal. Alternatively, the spring body 70 may be made of a vibration-damping steel plate sandwiched between plastic (sandwich steel plate). The spring body 70 may be made of any vibration-damping metal, but is preferably made of a vibration-damping alloy containing, by atomic weight, approximately 73% manganese, approximately 20% copper, approximately 5% nickel, and approximately 2% iron. The spring body 70 is preferably made of Mn-20Cu-5Ni-2Fe (M2052 alloy).

[0053] FIG. 3 is a perspective view showing the spring body 70. As shown in FIG. 3, the spring body 70 is composed of a cylindrical body 76 having slits 78, and the pitch of the spring portions 73 is unequal. Specifically, the pitch of both axial end portions 73a, 73b of the spring portion 73 is smaller than the pitch of the axial central portion 73c that connects the both axial end portions 73a, 73b of the spring portion 73. The spring portion 73 is substantially symmetrical with respect to an imaginary plane that passes through the approximate center in the axial direction and is substantially perpendicular to the axial direction. The spring constant of both end portions 73a, 73b of the spring portion 73 is greater than the spring constant of the central portion 73c.

[0054] Referring again to FIG. 1 , the axial displacement sensor 20 detects the axial displacement of the shaft portion 5b relative to the sleeve 10. The axial displacement sensor 20 is an optical encoder and includes a circular member 21 and a sensor main body 22. The circular member 21 is fitted onto and fixed to the shaft portion 5b. The outer peripheral surface of the circular member 21 constitutes a portion of the outer peripheral surface of the output shaft 5 in the axial direction. The circular member 21 is made of a material that has the property of reflecting at least a portion of light, such as glass, white resin, or transparent resin such as acrylic. The sensor main body 22 is fixed to an opposing portion 23 that is radially opposed to the circular member 21 and is a stationary portion that is integral with the sleeve 10 and is stationary relative to the sleeve 10.

[0055] FIG. 4 is a diagram illustrating the structure of the axial displacement sensor 20. More specifically, FIG. 4(a) is a schematic axial cross-sectional view of the axial displacement sensor 20, and FIG. 4(b) is a plan view of a portion of the circular member 21 as viewed from the radially outer side. As shown in FIG. 4, the circular member 21 includes a reflective pattern forming portion 21b on a cylindrical outer peripheral surface portion 21a whose central axis is the central axis of the output shaft 5. The reflective pattern forming portion 21b is provided with a reflective pattern 2 in a predetermined axial length range. The reflective portion 2a and the transmissive portion 2b reflect light and are alternately and regularly arranged multiple times in the axial direction at a pitch P2. For example, the reflective portion 2a reflects 95% of light, while the transmissive portion 2b reflects only 5% of light.

[0056] The reflective portion 2a is composed of a ridge portion extending around the entire circumference in the circumferential direction, and the transmissive portion 2b is composed of a groove portion provided between adjacent axial ridge portions and extending around the entire circumference in the circumferential direction. The sensor body 22 has two reading heads 22a, 22b that are adjacent to each other in the axial direction or spaced apart in the axial direction. The two reading heads 22a, 22b are arranged coaxially and approximately parallel to the axial direction. For ease of understanding, the reading heads 22a, 22b are indicated by dashed lines in Figure 4(b).

[0057] The reading heads 22a, 22b are identical and each have a first light-emitting unit 11a, 11b and a first light-receiving unit 14a, 14b. The first light-emitting units 11a, 11b preferably include LEDs. The first light-emitting units 11a, 11b are preferably arranged so that the optical axis of light emitted from the first light-emitting units 11a, 11b travels approximately on a plane including the center axis of the output shaft 5 and the radial direction of the output shaft 5. The circular member 21 and the first light-receiving unit 14a are arranged so that at least a portion of the light emitted from the first light-emitting unit 11a and reflected by the reflecting unit 2a is received by the first light-receiving unit 14b, and the circular member 21 and the first light-receiving unit 14b are arranged so that at least a portion of the light emitted from the first light-emitting unit 11b and reflected by the reflecting unit 2a is received by the first light-receiving unit 14b.

[0058] The reflective pattern forming portion 21b includes a periodic changing portion 2c in part. The output shaft 5 moves axially relative to the sleeve 10, and therefore also moves axially relative to the two leading heads 22a and 22b, which are stationary relative to the sleeve 10. The two leading heads 22a and 22b detect the reflective pattern 2. Furthermore, with regard to the range of axial movement of the output shaft 5 relative to the sleeve 10, the leading head 22b detects the periodic changing portion 2c while it is moving, while the leading head 22a cannot detect the periodic changing portion 2c. The leading head 22a is used for distance measurement (measurement of travel distance), and the leading head 22b is used for measuring the origin.

[0059] The starting position of the periodic change section 2c is referred to as the shift boundary 2d. Because the reflection pattern 2 of the reflective section 2a and the transmissive section 2b is regular within the distance measurement range, the outputs of the first light receiving sections 14a and 14b are approximately the same. In contrast, at a position including the periodic change section 2c, an output difference occurs between the outputs of the first light receiving sections 14a and 14b. The output signals of the first light receiving sections 14a and 14b are sinusoidal signals as long as the reflection pattern 2 detects a regular distance measurement range. However, when the shift boundary 2d passes through the leading head 22b, the output decreases and the period of the sinusoidal signal also increases slightly. This change in period and output returns to normal when the shift boundary 2d completely passes the leading head 22b.

[0060] Because the two reading heads 22a, 22b are substantially identical, there is no change in the periods of the output signals of the two reading heads 22a, 22b as long as they detect the distance measurement range in which the reflection pattern 2 is regularly arranged. On the other hand, if one of the reading heads 22a, 22b, detects the period-varying portion 2c while the other reading head 22a, is detecting the distance measurement range, a drop in output and a change in period occur. This change in period disappears when the period-varying portion 2c moves completely out of the detection range of the reading head 22b, so there is no change in the periods of the output signals of the two reading heads 22a, 22b in subsequent detections.

[0061] The shift boundary 2d is set as the origin, and the axial displacement of the output shaft 5 is detected by detecting this origin. The pitch P2 of the reflection pattern 2 may be set, for example, to 10 μm or more and 30 μm or less, or 15 μm or more and 25 μm or less. The pitch P2 of the reflection pattern 2 can be 20 μm. Furthermore, the pattern pitch P2m of the periodic varying portion 2c is set to be larger than the pitch P2 of the reflection pattern 2. For example, when the pitch P2 of the reflection pattern 2 is 20 μm, the pattern pitch P2m of the periodic varying portion 2c can be set to 24 μm. Based on the output signals of the reading heads 22a and 22b, the origin, which is the point where the difference between the pattern pitch P2m and the pattern pitch P2 is 4 μm, can be detected. Based on the position of the origin, the axial displacement of the output shaft 5 relative to the sleeve 10 can be detected.

[0062] A method of providing a reflection pattern on a plate-like substrate and determining the relative displacement of a shaft member is described, for example, in Japanese Patent Application Laid-Open No. 2022-66437. The same analytical method as that described in the above publication can be used as an analytical method for detecting (calculating) the axial displacement of the output shaft 5 from the signals of the reading heads 22a and 22b. In this embodiment, the axial displacement detection unit 86a, which will be described later, performs this analysis and detects the axial displacement of the output shaft 5 relative to the sleeve 10.

[0063] A method of providing a reflective pattern on a plate-like member to detect the axial displacement of one member relative to another member is known in many documents, including the aforementioned JP 2022-66437 A. However, at the time of filing this application, there was no mechanism that had a shaft member that moved axially relative to a stationary member and provided the optical scale of an optical encoder on the outer circumferential surface of the shaft member. This was because it was believed that if the optical scale of an optical encoder was provided on something other than a plate member, the axial displacement of the moving member relative to the stationary member could not be accurately detected.

[0064] However, the applicant of the present application discovered for the first time, through conducting numerous tests over a long period of time, that even if an optical scale is provided on the outer surface of the shaft member, for example, on the outer surface of the shaft member which is composed of a curved surface, it is possible to accurately detect the axial displacement of the shaft member relative to the stationary part by emitting light from an emitting unit installed in the stationary part to the optical scale to create an optical signal, and then reading that optical signal with a photodetector.

[0065] That is, the inventors have found for the first time that even when an optical scale (reflection pattern 2) is provided on the curved portion of the outer peripheral surface of the output shaft 5, it is possible to detect the axial displacement of the output shaft 5 relative to the sleeve 10 with high accuracy at the level of several nm to several tens of nm. Note that the inventors have also confirmed that by arranging the first light-emitting units 11a and 11b so that the optical axis of the light emitted from the first light-emitting units 11a and 11b progresses substantially on a plane including the central axis of the output shaft 5 and the radial direction of the output shaft 5, it is possible to detect the axial displacement of the shaft member relative to the stationary part with even higher accuracy.

[0066] 1 again, rotation angle detection sensor 40 detects the rotation angle (circumferential displacement) of shaft portion 5b relative to sleeve 10. Rotation angle detection sensor 40 is an optical encoder, and includes an annular member 21 and a sensor main body 42. Sensor main body 42 is a stationary portion that is integrally formed with sleeve 10 and is stationary relative to sleeve 10, and is fixed to an opposing portion 43 that is spaced apart from sensor main body 22 in the axial direction and faces the annular member 21 in the radial direction (radial direction of output shaft 5).

[0067] FIG. 5 is a diagram illustrating the structure of the rotation angle detection sensor 40, and FIG. 6 is a plan view of a portion of the circular member 21 as viewed from the radially outward side. As shown in FIG. 5, the circular member 21 includes a reflective pattern forming portion 21c on a cylindrical outer peripheral surface portion 21a whose central axis is the central axis of the output shaft 5. The reflective pattern forming portion 21c has a reflective pattern 4 formed thereon over a predetermined axial length range. The reflective pattern forming portion 21c has reflective portions 4a and transmissive portions 4b that reflect light and are alternately and regularly arranged multiple times in the circumferential direction at a pitch P4. As shown in FIG. 6, the reflective pattern forming portion 21c is provided adjacent to the reflective pattern forming portion 21b in the axial direction. The reflective pattern forming portion 21c is provided in an axial range of the circular member 21 that is different from the axial range in which the reflective pattern forming portion 21b is provided.

[0068] As shown in Figure 5, the reflecting section 4a is composed of axially extending protrusions, and the transmitting section 4b is composed of axially extending grooves provided between circumferentially adjacent protrusions. The sensor body 42 has two reading heads 42a, 42b that are circumferentially adjacent or spaced apart. The two reading heads 42a, 42b are arranged on the same circumference (circumferences with the same radius) at the same axial position.

[0069] The reading heads 42a, 42b are identical. Each of the reading heads 42a, 42b has a second light-emitting unit 41a, 41b and a second light-receiving unit 44a, 44b. The second light-emitting units 41a, 41b preferably include an LED. The second light-emitting units 41a, 41b are preferably arranged so that the optical axis of the light emitted from the second light-emitting units 41a, 41b travels approximately on a plane approximately perpendicular to the central axis of the output shaft 5. The circular member 21 and the second light-receiving unit 44a are arranged so that at least a portion of the light emitted from the second light-emitting unit 41a and reflected by the reflecting unit 4a is received by the second light-receiving unit 44a, and the circular member 21 and the second light-receiving unit 44b are arranged so that at least a portion of the light emitted from the second light-emitting unit 41b and reflected by the reflecting unit 4a is received by the second light-receiving unit 44b.

[0070] The reflective pattern forming portion 21c includes a periodic changing portion 4c in part. The output shaft 5 rotates circumferentially relative to the sleeve 10, and therefore also rotates circumferentially relative to the two leading heads 42a and 42b that are stationary relative to the sleeve 10. The two leading heads 42a and 42b detect the reflective pattern 4. Within the range of circumferential rotation of the output shaft 5 relative to the sleeve 10, the leading head 42b detects the periodic changing portion 4c while it is moving, while the leading head 42a cannot detect the periodic changing portion 4c. The leading head 42a is used for distance measurement (measuring the distance traveled), and the leading head 42b is used for measuring the origin.

[0071] The starting position of the periodic change section 4c is referred to as the shift boundary 4d. Because the reflection pattern 4 of the reflective section 4a and the transmissive section 4b is regular within the distance measurement range, the outputs of the second light receiving sections 44a and 44b are approximately the same. In contrast, at a position including the periodic change section 4c, an output difference occurs between the outputs of the second light receiving sections 44a and 44b. The output signals of the second light receiving sections 44a and 44b are sinusoidal signals as long as the reflection pattern 4 detects a regular distance measurement range. However, when the shift boundary 4d passes through the reading head 42b, the output decreases and the period of the sinusoidal signal also increases slightly. This change in period and output returns to normal when the shift boundary 4d completely passes the reading head 42b.

[0072] Because the two reading heads 42a, 42b are substantially identical, there is no change in the periods of the output signals of the two reading heads 42a, 42b as long as the reading heads 42a, 42b detect the distance measurement range in which the reflective pattern 4 is regularly arranged. On the other hand, if one of the reading heads 42a, 42b, detects the period-varying portion 4c while the other reading head 42a, is detecting the distance measurement range, a drop in output and a change in period occur. This change in period disappears when the period-varying portion 4c moves completely out of the detection range of the reading head 42b, so there is no change in the periods of the output signals of the two reading heads 42a, 42b in subsequent detections.

[0073] The shift boundary 4d is set as the origin, and the rotational displacement of the output shaft 5 is detected by detecting this origin. The pitch P4 of the reflection pattern 4 may be set, for example, to 10 μm or more and 30 μm or less, or 15 μm or more and 25 μm or less. The pitch P4 of the reflection pattern 4 can be 20 μm. Furthermore, the pattern pitch P4m of the periodic varying portion 4c is set to be larger than the pitch P4 of the reflection pattern 2. For example, when the pitch P4 of the reflection pattern 4 is 20 μm, the pattern pitch P4m of the periodic varying portion 4c can be set to 24 μm. Based on the output signals of the reading heads 42a and 42b, the origin, which is the point where the difference between the pattern pitch P4m and the pattern pitch P4 is 4 μm, can be detected, and the relative angle of the output shaft 5 with respect to the sleeve 10 can be detected based on the position of the origin.

[0074] As an analysis method for detecting (calculating) the circumferential displacement of the output shaft 5 from the signals of the reading heads 42a, 42b, for example, the same analysis method as that described in the above-mentioned Japanese Patent Application Laid-Open No. 2022-66437 can be used. In this embodiment, the rotation drive control unit 86d described later performs this analysis to detect the circumferential displacement of the output shaft 5 relative to the sleeve 10, and detects the rotation angle of the output shaft 5 relative to the sleeve 10, which corresponds one-to-one to the circumferential displacement of the output shaft 5.

[0075] A method for detecting the rotational displacement (circumferential displacement) of one member relative to another member by providing a reflective pattern on a disk member is known. However, at the time of filing this application, there was no mechanism having a shaft member that moves circumferentially relative to a stationary member, and in which the optical scale of an optical encoder is provided on the outer peripheral surface of the shaft member. This is because it was thought that if the optical scale of an optical encoder is provided on a curved surface other than a disk member (other than a flat surface), as in the technology disclosed herein, it would be impossible to accurately detect the circumferential displacement of a moving member relative to a stationary member.

[0076] However, the applicant of the present application discovered for the first time, through conducting numerous tests over a long period of time, that even if an optical scale is provided on the outer surface of the shaft member, for example, on the outer surface of the shaft member that is composed of a curved surface, it is possible to accurately detect the circumferential displacement of the shaft member relative to the stationary part by emitting light from an emitting unit installed in the stationary part to the optical scale to create an optical signal, and then reading that optical signal with a light receiving element.

[0077] That is, it was found for the first time that even when an optical scale (reflective pattern 4) is provided on the curved portion of the outer peripheral surface of the output shaft 5, it is possible to detect the circumferential displacement of the output shaft 5 relative to the sleeve 10 with high accuracy at the level of several nm to several tens of nm. Note that the inventors have also confirmed that by arranging the second light-emitting units 41a, 41b so that the optical axis of the light emitted from the second light-emitting units 41a, 41b travels approximately on a plane approximately perpendicular to the central axis of the output shaft 5, it is possible to detect the circumferential displacement of the shaft member relative to the stationary part with even higher accuracy.

[0078] Referring to FIG. 1, the fluid pressure actuator 1 is controlled by an externally disposed control device 85. The control device 85 is preferably configured by a computer, for example, a microcomputer, and includes a control unit 86 and a storage unit 87. The control unit 86, i.e., a processor, includes, for example, a CPU (Central Processing Unit). The storage unit 87 is configured by a hard disk drive (HDD), a semiconductor memory, etc., and the semiconductor memory is configured by a non-volatile memory such as a ROM (Read Only Memory) or a volatile memory such as a RAM (Random Access Memory). The storage unit 87 may be configured by only one storage medium or by multiple different storage media. The CPU reads and executes a control program for the fluid pressure actuator 1 that is pre-stored in the storage unit 87. The non-volatile memory pre-stores the control program, predetermined thresholds, etc. The volatile memory temporarily stores the read control program and processing data.

[0079] The control unit 86 includes an axial displacement detection unit 86a, a rotation angle detection unit 86b as a circumferential displacement detection unit, an advance / retreat drive control unit 86c, and a rotation drive control unit 86d. The axial displacement detection unit 86a detects the axial displacement of the output shaft 5 relative to the sleeve 10 based on a signal from the axial displacement sensor 20, and the rotation angle detection unit 86b detects the rotation angle of the output shaft 5 relative to the sleeve 10 based on a signal from the rotation angle detection sensor 40.

[0080] The advance / retract drive control unit 86c controls the advance / retract drive unit 30 based on the axial displacement of the output shaft 5 relative to the sleeve 10 detected (calculated) by the axial displacement detection unit 86a, thereby controlling the axial displacement of the output shaft 5 relative to the sleeve 10 with high precision. Because the rotating unit 53 is stationary in the axial direction relative to the sleeve 10 and the rear end 72 of the spring body 70 is fixed to the rotating unit 53, determining the axial displacement of the output shaft 5 relative to the sleeve 10 makes it possible to determine the axial forward extension dimension Δx of the spring body 70 relative to its natural length. Therefore, if the axial forward force applied to the output shaft 5 by the air supplied from the servo valve 31 of the advance / retract drive unit 30 to the first and second pressure chambers 9a, 9b is F(S) and the spring constant of the spring body 70 is k, the axial forward external force applied to the output shaft 5 is F(S)-k×Δx. The forward / backward drive control unit 86c back-calculates F(S) that will achieve the desired axial position of the output shaft 5 based on the external force, and controls the amount of air discharged or sucked in from the first and second discharge and suction ports of the servo valve 31 so as to achieve that F(S).

[0081] The rotational drive control unit 86d controls the rotational drive unit 50 based on the rotational angle of the output shaft 5 relative to the sleeve 10 detected (calculated) by the rotational angle detection unit 86b, and controls the rotational angle of the output shaft 5 relative to the sleeve 10 with high precision. The circumferential displacement of the output shaft 5 relative to the sleeve 10 corresponds one-to-one to the rotational angle of the output shaft 5 relative to the sleeve 10. Since the diameter of the cylindrical outer peripheral surface portion 21a is known, if the circumferential displacement of the output shaft 5 relative to the sleeve 10 can be detected, the rotational angle of the output shaft 5 relative to the sleeve 10 can also be easily detected.

[0082] Because the rear end of the spring body 70 is fixed to the rotating part 53, if the rotation angle of the output shaft 5 relative to the sleeve 10 can be determined, the degree of circumferential torsion of the spring body 70 can be determined based on the rotation angle of the rotating part 53 relative to the sleeve 10, and the torque T(S) (circumferential force) applied by the spring body 70 to the output shaft 5 can be determined. The rotation drive control part 86d controls the servo valve 51 of the rotation drive part 50 to control the rotation angle of the rotating part 53 relative to the sleeve 10, thereby adjusting the torque T(S) with high precision and controlling the rotation angle of the output shaft 5 relative to the sleeve 10 with high precision.

[0083] A first displacement detection device 25 (see Figure 1) according to the present disclosure comprises a sleeve (stationary portion) 10, an output shaft (shaft member) 5, an advancing / retracting drive unit (shaft member advancing / retracting drive unit) 30 that enables axial displacement of the output shaft 5 relative to the sleeve 10, a plurality of reflecting portions (first protrusion portions) 2a arranged at intervals in the axial direction on the outer peripheral surface of the output shaft 5, first light-emitting portions 11a, 11b that are stationary relative to the sleeve 10 and that emit light toward the reflecting portion 2a, first light-receiving portions 14a, 14b that receive at least a portion of the light that is emitted from the first light-emitting portions 11a, 11b and reaches the axial range on the output shaft 5 where the reflecting portion 2a is provided, and an axial displacement detection unit 86a that detects axial displacement of the output shaft 5 relative to the sleeve 10 based on the light received by the first light-receiving portions 14a, 14b.

[0084] The reflective portion (first protrusion portion) 2a may be provided so as to protrude radially outward from an outer peripheral surface portion of the output shaft 5 where the reflective portion 2a is not present, or may be provided between adjacent grooves by providing multiple grooves on the outer peripheral surface of the output shaft 5.

[0085] The applicant of the present application discovered for the first time that even when an optical scale (reflective portion 2a and transmissive portion 2b) is provided on the outer peripheral surface of output shaft 5, for example, on the outer peripheral surface of output shaft 5 that is formed by a curved surface, it is possible to accurately detect the axial displacement of the shaft member (output shaft 5) relative to the stationary portion by emitting light from light-emitting portions (first light-emitting portions 11a, 11b) installed in the stationary portion (sleeve 10) to the optical scale to generate an optical signal, and then reading the optical signal with first light-receiving portions 14a, 14b. The first displacement detection device 25 of the present disclosure can accurately detect the axial displacement of the output shaft 5 relative to the sleeve 10, and can easily detect, for example, axial displacement of the output shaft 5 relative to the sleeve 10 on the order of several nanometers.

[0086] In addition, a second displacement detection device 45 (see Figure 1) of the present disclosure includes a sleeve (stationary portion) 10, an output shaft (shaft member) 5, a rotational drive unit (shaft member rotational drive unit) 50 that enables rotational displacement of the output shaft 5 relative to the sleeve 10, a plurality of reflecting portions (second protrusion portions) 4a arranged at intervals circumferentially on the outer peripheral surface of the output shaft 5, second light-emitting portions 41a, 41b that are stationary with respect to the sleeve 10 and emit light toward the reflecting portions 4a, second light-receiving portions 44a, 44b that receive at least a portion of the light that is emitted from the second light-emitting portions 41a, 41b and reaches the circumferential range on the output shaft 5 in which the reflecting portions 4a are provided, and a rotational angle detection unit (circumferential displacement detection unit) 86b that detects circumferential displacement of the output shaft 5 relative to the sleeve 10 based on the light received by the second light-receiving portions 44a, 44b. According to the present disclosure, circumferential displacement of the output shaft 5 relative to the sleeve 10 can be detected accurately, and for example, circumferential displacement of the output shaft 5 relative to the sleeve 10 at the level of several nanometers can be easily detected.

[0087] The applicant of the present application discovered for the first time that even when an optical scale (reflective portion 4a and transmissive portion 4b) is provided on the outer peripheral surface of the output shaft 5, for example, on the outer peripheral surface of the output shaft 5 that is formed by a curved surface, it is possible to accurately detect the circumferential displacement of the shaft member (output shaft 5) relative to the stationary portion by emitting light from light-emitting portions (second light-emitting portions 41a, 41b) installed on the stationary portion (sleeve 10) to the optical scale to generate an optical signal, and then reading the optical signal with second light-receiving portions 44a, 44b. The second displacement detection device 45 of the present disclosure can accurately detect the circumferential displacement of the output shaft 5 relative to the sleeve 10, and can easily detect, for example, circumferential displacement of the output shaft 5 relative to the sleeve 10 on the order of several nanometers.

[0088] The displacement detection device 75 (see FIG. 1) also includes a sleeve (stationary portion) 10, an output shaft (shaft member) 5, an advance / retract drive portion (shaft member advance / retract drive portion) 30 that enables axial displacement of the output shaft 5 relative to the sleeve 10, a plurality of reflecting portions (first protrusion portions) 2a arranged at intervals in the axial direction on the outer peripheral surface of the output shaft 5, first light-emitting portions 11a, 11b that are stationary relative to the sleeve 10 and that emit light toward the reflecting portion 2a, first light-receiving portions 14a, 14b that receive at least a portion of the light that is emitted from the first light-emitting portions 11a, 11b and reaches the axial range on the output shaft 5 where the reflecting portion 2a is provided, and an axial displacement detection portion 86a that detects axial displacement of the output shaft 5 relative to the sleeve 10 based on the light received by the first light-receiving portions 14a, 14b. In addition, the displacement detection device 75 may further include a rotational drive unit (shaft member rotational drive unit) 50 that enables rotational displacement of the output shaft 5 relative to the sleeve 10, a plurality of reflecting portions (second protrusion portions) 4a that are arranged at intervals circumferentially on the outer peripheral surface of the output shaft 5, second light-emitting portions 41a, 41b that are stationary with respect to the sleeve 10 and that emit light toward the reflecting portions 4a, second light-receiving portions 44a, 44b that receive at least a portion of the light that is emitted from the second light-emitting portions 41a, 41b and reaches the circumferential range on the output shaft 5 in which the reflecting portions 4a are provided, and a rotational angle detection unit (circumferential displacement detection unit) 86b that detects circumferential displacement of the output shaft 5 relative to the sleeve 10 based on the light received by the second light-receiving portions 44a, 44b.

[0089] According to this configuration, in addition to accurately detecting the axial displacement of the output shaft 5 relative to the sleeve 10, it is also possible to accurately detect the circumferential displacement of the output shaft 5 relative to the sleeve 10. For example, in addition to detecting the axial displacement of the output shaft 5 relative to the sleeve 10 at the level of a few nanometers, it is also easy to detect the circumferential displacement of the output shaft 5 relative to the sleeve 10 at the level of a few nanometers.

[0090] In addition, the first displacement detection method of the present disclosure includes the steps of irradiating light from first light-emitting elements 11a, 11b, which are stationary with respect to the sleeve (stationary portion) 10, to a first protrusion portion of an output shaft (shaft member) 5, which is movable axially relative to the sleeve 10 and has a plurality of first protrusion portions (reflective portions 2a) arranged at intervals in the axial direction on a cylindrical outer peripheral surface portion 21a, which is an example of an outer peripheral surface, and detecting axial displacement of the output shaft 5 relative to the sleeve 10 based on at least a portion of the light emitted from the first light-emitting elements 11a, 11b and reaching the axial range of the output shaft 5 in which the first protrusion portions are provided.

[0091] According to the present disclosure, the axial displacement of the output shaft 5 relative to the sleeve 10 can be accurately detected, and for example, it is easy to detect the axial displacement of the output shaft 5 relative to the sleeve 10 at the level of several nanometers.

[0092] Furthermore, the first displacement detection method disclosed above may further include a step in which the output shaft 5 is movable circumferentially relative to the sleeve 10 and has a plurality of second protrusions (reflecting portions 4a) arranged at intervals circumferentially on the cylindrical outer peripheral surface portion 21a, and the step of irradiating light onto the second protrusions from second light-emitting portions 41a, 41b that are stationary relative to the sleeve 10, and a step of detecting circumferential displacement of the output shaft 5 relative to the sleeve 10 based on at least a portion of the light emitted from the second light-emitting portions 41a, 41b and reaching the circumferential range of the output shaft 5 in which the second protrusions are provided.

[0093] According to this configuration, in addition to accurately detecting the axial displacement of the output shaft 5 relative to the sleeve 10, it is also possible to accurately detect the circumferential displacement of the output shaft 5 relative to the sleeve 10, making it easy to detect not only the axial displacement of the output shaft 5 relative to the sleeve 10 at the level of a few nanometers, but also the circumferential displacement of the output shaft 5 relative to the sleeve 10 at the level of a few nanometers.

[0094] Furthermore, the displacement detection method of the present disclosure may be configured to be unable to detect axial displacement of the shaft member relative to the stationary portion, but capable of detecting circumferential displacement of the shaft member relative to the stationary portion. That is, a second displacement detection method, which is another aspect of the present disclosure, includes the steps of: irradiating light from second light-emitting elements 41 a, 41 b stationary with respect to sleeve (stationary portion) 10 onto second ridges (reflecting portions 4 a) of an output shaft (shaft member) 5 that is movable circumferentially relative to sleeve 10 and has a cylindrical outer peripheral surface portion 21 a, which is an example of an outer peripheral surface, with the second ridges; and detecting circumferential displacement of the output shaft 5 relative to sleeve 10 based on at least a portion of the light emitted from second light-emitting elements 41 a, 41 b and reaching the circumferential range of the output shaft 5 where the second ridges are provided. According to the present disclosure, circumferential displacement of the output shaft 5 relative to sleeve 10 can be accurately detected, and it is easy to detect circumferential displacement of the output shaft 5 at the level of several nanometers, for example.

[0095] The fluid pressure actuator 1 of the present disclosure also includes an output shaft 5 having at least one annular end face 8a, 8b (first pressure-receiving surface), a plurality of first protrusions (reflecting portions 2a) spaced axially on a cylindrical outer peripheral surface portion 21a as an example of an outer peripheral surface, and a plurality of second protrusions (reflecting portions 4a) spaced circumferentially on the cylindrical outer peripheral surface portion 21a, and a sleeve 10 having inner peripheral surface portions 10a, 10b that support the output shaft 5 movably in the axial direction, and annular end faces 10c, 10d (second pressure-receiving surfaces) that, together with the end faces 8a, 8b, define at least a portion of the first and second pressure chambers 9a, 9b.

[0096] The fluid pressure actuator 1 also includes an advance / retract drive unit 30 that varies the volume of the first and second pressure chambers 9a, 9b by changing the amount of fluid supplied to the first and second pressure chambers 9a, 9b, thereby moving the output shaft 5 forward and backward in the axial direction relative to the sleeve 10, and a rotating unit 53 that is arranged radially outward of the output shaft 5 and rotatably approximately coaxial with the output shaft 5. The fluid pressure actuator 1 also includes a spring body 70 that is arranged radially outward of the output shaft 5 and approximately coaxial with the output shaft 5 so as to be radially extendable and contractible, and has a front end 71 (one side end) fixed to the output shaft 5 and a rear end 72 (the other side end) fixed to the rotating unit 53, and that rotates the output shaft 5 in the circumferential direction when the rotating unit 53 is rotationally driven.

[0097] The fluid pressure actuator 1 also includes an axial displacement sensor (first sensor) 20 that is stationary with respect to the sleeve 10 and includes first light-emitting elements 11a, 11b that emit light toward the first protrusion portion and first light-receiving elements 14a, 14b that receive at least a portion of the light that is emitted from the first light-emitting elements 11a, 11b and reaches the axial range of the output shaft 5 in which the first protrusion portion is provided, and an axial displacement detection unit 86a that detects the axial displacement of the output shaft 5 with respect to the sleeve 10 based on the light received by the first light-receiving elements 14a, 14b.

[0098] The fluid pressure actuator 1 also includes a rotation angle detection sensor (second sensor) 40 that is stationary with respect to the sleeve 10 and includes second light-emitting elements 41a, 41b that emit light toward the second protrusion portion and second light-receiving elements 44a, 44b that receive at least a portion of the light that is emitted from the second light-emitting elements 41a, 41b and reaches the circumferential range of the output shaft 5 in which the second protrusion portion is provided, and a rotation angle detection unit (circumferential displacement detection unit) 86b that detects the circumferential displacement of the output shaft 5 with respect to the sleeve 10 based on the light received by the second light-receiving elements 44a, 44b.

[0099] According to the fluid pressure actuator of the present disclosure, in addition to accurately detecting the axial displacement of the output shaft 5 relative to the sleeve 10, it is also possible to accurately detect the circumferential displacement of the output shaft 5 relative to the sleeve 10, and in addition to detecting the axial displacement of the output shaft 5 relative to the sleeve 10 at the level of a few nanometers, it is also possible to easily detect the circumferential displacement of the output shaft 5 relative to the sleeve 10 at the level of a few nanometers.

[0100] In the first embodiment, the rotary drive unit 50 includes a servo valve 51 having only one vane 55. However, the rotary drive unit may include a servo valve having two or more vanes. For example, as shown in FIG. 7, a schematic cross-sectional view of a modified servo valve 151 corresponding to FIG. 2, the servo valve 151 of the rotary drive unit 150 may include a cylindrical case 152, a cylindrical rotating unit 153, two protrusions 154a and 154b, two vanes 155a and 155b, and four discharge and suction ports 157a to 157d. The two protrusions 154a and 154b extend in the same straight line and radially face the rotating unit 153, and the two vanes 155a and 155b also extend in the same straight line and radially face the cylindrical case 152. Furthermore, the discharge and suction ports 157a and 157d perform the same operation (air discharge or suction) at the same timing, and the discharge and suction ports 157b and 157c perform the same operation at the same timing but in the opposite direction to the discharge and suction ports 157a and 157d (air suction or discharge).

[0101] When the servo valve 151 having two vanes 155a, 155b shown in FIG. 7 is employed, the angle at which the rotating part 153 can rotate is smaller than that of the rotary drive part 50 shown in FIG. 2, but the torque that can be applied to the rotating part 153 can be approximately twice that of the rotary drive part 50 shown in FIG. 2, making it easier to apply a large torque to the output shaft 5. The rotary drive part may have a motor instead of a servo valve. Then, a gear fixed to the output shaft of the motor may be meshed with a gear fixed to the cylindrical outer peripheral surface of the rotating part, thereby transmitting the rotational power of the motor to the rotating part and rotating the rotating part.

[0102] In addition, the spring body 70 is configured as a cylinder 76 provided with slits 78, and the pitch at both ends of the spring body 70 is shorter than the pitch at the center of the spring body. However, as shown in Fig. 8, i.e., a perspective view of a modified spring body 90, the spring body 90 may be configured as a coil spring, and the pitch at both ends 91, 92 of the spring body 90 may be shorter than the pitch at the center 93 of the spring body 90.

[0103] Alternatively, the fluid pressure actuator of the present disclosure may employ any spring element with an unequal pitch such that the pitch at both ends is not shorter than the pitch at the center. For example, the fluid pressure actuator of the present disclosure may employ a spring element with a longer pitch at both ends than the pitch at the center. Alternatively, the fluid pressure actuator of the present disclosure may employ a spring element with the same pitch on the front side of the axial center of the spring element and the same pitch on the rear side of the axial center of the spring element, but with the pitch on the front side different from the pitch on the rear side.

[0104] Furthermore, although the case where the spring body 70 is made of a damping metal and the pitch of the spring body 70 is an irregular pitch has been described, the spring body provided in the fluid pressure actuator of the present disclosure may be made of a damping metal but the pitch of the spring body may not be an irregular pitch. Alternatively, the spring body provided in the fluid pressure actuator of the present disclosure may not be made of a damping metal but the pitch of the spring body may be an irregular pitch, or the spring body provided in the fluid pressure actuator of the present disclosure may not be made of a damping metal but the pitch of the spring body may not be an irregular pitch.

[0105] The fluid pressure actuator of the present disclosure may be used as a chip mounter that presses and mounts an electronic component, such as a chip, in a predetermined position on a molten wiring on a substrate. While the control device 85 has been described as being located outside the fluid pressure actuator 1, the fluid pressure actuator of the present disclosure may also include a control device. The fluid pressure actuator of the present disclosure may also have a collet at the axially forward end. The fluid pressure actuator of the present disclosure may also have a passage inside the output shaft that connects to an external vacuum pump and opens to the axially forward end face of the collet. With this configuration, an electronic component can be attracted to the collet of the fluid pressure actuator by drawing a vacuum with the vacuum pump, and the electronic component can be released from the collet by stopping the vacuum pump.

[0106] (Second embodiment) In the above embodiment, the first protrusion (reflecting portion 2a) of the axial displacement sensor 20 and the second protrusion (reflecting portion 4a) of the rotation angle detection sensor 40 are arranged adjacent to each other in the axial direction or spaced apart in the axial direction, and the first protrusion does not include a portion located in the same axial range as the second protrusion. However, there are cases where the rotation angle of the shaft member from the reference position relative to the stationary portion is limited to a predetermined angle or less (e.g., ±20 degrees or less). In such cases, if the first protrusion includes a portion located in the same axial range as the second protrusion, the axial dimension of the device can be reduced, resulting in a compact device. In the second embodiment, such a device will be described.

[0107] 9 is an axial cross-sectional view of a fluid pressure actuator 101 of the second embodiment, corresponding to FIG. 9. As shown in FIG. 9, in the fluid pressure actuator 101, the circumferential center position of the sensor main body 122 of the axial displacement sensor 120 and the circumferential center position of the sensor main body 142 of the rotation angle detection sensor 140 are disposed at an interval of 180 degrees in the circumferential direction of the output shaft 105. In addition, the axial center position of the sensor main body 122 substantially coincides with the axial center position of the sensor main body 142.

[0108] Fig. 10 is a plan view of the annular member 121 that constitutes a part of the output shaft 105 of the fluid pressure actuator 101, as seen from the radially outward direction, and Fig. 11 is a cross-sectional view of the output shaft 105 when cut along a plane that passes through the axial center position of the sensor main body 122 and includes the radial direction. In Fig. 11, the circumferential range indicated by X1 is the circumferential range in which the first protrusion portion (reflecting portion 102a) is provided, and the circumferential range indicated by X2 is the circumferential range in which the second protrusion portion (reflecting portion 104a) is provided.

[0109] As shown in FIG. 11, in the fluid pressure actuator 101, at a reference position of the output shaft 105, for example, in this embodiment, at a position where the output shaft 105 is not subjected to torque T from the spring body 70 and is not subjected to axial force from the spring body 70, the circumferential center position of the sensor body 122 is radially opposed to the circumferential center position Q1 of the circumferential formation range of the first protrusion portion (hereinafter referred to as the first circumferential center position), and the circumferential center position of the sensor body 142 is radially opposed to the circumferential center position Q2 of the second protrusion portion (reflecting portion 104a) (hereinafter referred to as the second circumferential center position).

[0110] In this embodiment, the first protrusions are formed within a circumferential range of ±22.5° around the first circumferential center position Q1, and the second protrusions are formed within a circumferential range of ±22.5° around the second circumferential center position Q2. If the first protrusions and the second protrusions are formed within such circumferential ranges, then as long as the output shaft 105 rotates within the circumferential range of ±22.5° around the first circumferential center position Q1, the axial displacement sensor 120 can detect the axial displacement of the output shaft 105 relative to the sleeve 10 without being affected by the second protrusions, and the rotation angle detection sensor 140 can detect the circumferential displacement of the output shaft 105 relative to the sleeve 10 without being affected by the second protrusions.

[0111] In this embodiment, the first protrusions are formed within a circumferential range of ±22.5° around the first circumferential center position Q1, but the first protrusions may be formed within a circumferential range of ±α° around the first circumferential center position Q1, where α° may be any angle less than 22.5°. Furthermore, the second protrusions are formed within a circumferential range of ±22.5° around the second circumferential center position Q2, but the second protrusions may be formed within a circumferential range of ±β° around the second circumferential center position Q2, where β° may be any angle less than 22.5°.

[0112] Alternatively, the circumferential range of the first protrusions may be within a circumferential range of ±γ° around the first circumferential center position Q1, where γ° may be an angle greater than 22.5°.Furthermore, the circumferential range of the second protrusions may be within a circumferential range of ±δ° around the second circumferential center position Q2, where δ° may be an angle greater than 22.5°.

[0113] It is sufficient that at least a portion of the axial formation range of the first ridge portions overlaps with the axial formation range of the second ridge portions, and the axial formation range of the first ridge portions may or may not coincide with the axial formation range of the second ridge portions as shown in Figure 10. According to the second embodiment, the axial dimension of the fluid pressure actuator 101 can be reduced, and a compact fluid pressure actuator 101 can be realized.

[0114] The present disclosure is not limited to the above-described embodiment and its modifications, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents.

[0115] For example, in the above embodiment, a fluid pressure actuator is described as being used to position a second substrate relative to a first substrate with a precision of several nanometers in the manufacture of semiconductor chips using multilayer substrates. However, the fluid pressure actuator of the present disclosure may also be used for other purposes, such as a materials testing machine, for example, to twist and pull a material fixed to the front end surface of the output shaft in the X direction, or to test the durability of the material.

[0116] In addition, the technology disclosed herein has been described as being used to detect both axial and circumferential displacement of a shaft member relative to a stationary part. However, the technology disclosed herein may be used to detect only axial displacement of a shaft member relative to a stationary part, or may be used to detect only circumferential displacement of a shaft member relative to a stationary part. In addition, the technology disclosed herein has been described as being applied to a fluid pressure actuator 1, 101. However, the technology disclosed herein may be applied to any device in which a shaft member displaces axially relative to a stationary part to detect axial displacement.

[0117] Alternatively, the technology of the present disclosure may be applied to any device in which a shaft member displaces circumferentially relative to a stationary part to detect circumferential displacement. Alternatively, the technology of the present disclosure may be applied to any device in which a shaft member displaces both axially and circumferentially relative to a stationary part to detect both axial and circumferential displacement. Furthermore, the axial distance between adjacent first protrusions on the shaft member may be any length equal to or greater than 30 μm, and the circumferential distance between adjacent second protrusions on the shaft member may be any length equal to or greater than 30 μm.

[0118] Also, in the above description, the circular member 21 is fitted and fixed to the output shaft 5, and the reflective patterns 2, 4 are formed on the outer peripheral surface of the circular member 21. However, the reflective patterns may be formed on the outer peripheral surface of the output shaft of the circular member itself. Also, in the above description, the shaft member (output shaft 5) is displaced in the circumferential direction relative to the stationary part (sleeve 10) based on torque caused by torsion of the spring bodies 70, 90. However, the rotational power of the shaft member rotation drive unit formed by a motor or the like may be transmitted to the shaft member without passing through the spring bodies, and in this case, the rotational power may be transmitted using, for example, meshing. [Explanation of symbols]

[0119] REFERENCE SIGNS LIST 1 fluid pressure actuator, 2 reflection pattern, 2a reflection portion, 2b transmission portion, 2c periodic change portion, 2d shift boundary, 4 reflection pattern, 4a reflection portion, 4b transmission portion, 4c periodic change portion, 4d shift boundary, 5 output shaft, 5a cylindrical portion, 5b shaft portion, 5c flange portion, 6 nut, 7 cylindrical outer peripheral surface, 8a, 8b end face, 9a second pressure chamber, 9b second pressure chamber, 10 sleeve, 10a first inner peripheral surface portion, 10b second inner peripheral surface portion, 10c end face, 11a, 11b first light emitting portion, 14a, 14b first light receiving portion, 20 axial displacement sensor, 21 annular member, 21a cylindrical outer peripheral surface portion, 21b reflection pattern forming portion, 21c Reflective pattern forming section, 22 sensor body, 22a, 22b reading head, 23 opposing section, 25 first displacement detection device, 30 forward / backward driving section, 31 servo valve, 32a first passage, 32b second passage, 32c third passage, 32d fourth passage, 32e fifth passage, 32f sixth passage, 40 rotation angle detection sensor, 41a, 41b second light emitting section, 42 sensor body, 42a, 42b reading head, 43 opposing section, 44a, 44b second light receiving section, 45 second displacement detection device, 50 rotation driving section, 51 servo valve, 52 case, 52a cylinder inner peripheral surface, 53 rotating section, 53a cylinder outer peripheral surface, 54 protrusion, 55 vane, 56a Pressure chamber, 57a, 57b Discharge and suction port, 58 Wall portion, 65 Flange portion, 70 Spring body, 71 Front end portion, 72 Rear end portion, 73 Spring portion, 73a, 73b Both ends, 73c Central portion, 75 Displacement detection device, 76 Cylinder, 78 Slit, 85 Control device, 86 Control portion, 86a Axial displacement detection portion, 86b Rotation angle detection portion, 86c Advance / retreat drive control portion, 86d Rotation drive control portion, 87 Memory portion, 90 Spring body, 91, 92 Both ends, 93 Central portion, 101 Fluid pressure actuator, 102a Reflection portion, 104a Reflection portion, 105 Output shaft, 120 Axial displacement sensor, 121 Circular member, 122 Sensor body, 140 rotation angle detection sensor, 142 sensor body.

Claims

1. A stationary portion; A shaft member; a shaft member forward / backward driving unit that enables axial displacement of the shaft member relative to the stationary unit; a plurality of first protrusions arranged at intervals in the axial direction on an outer peripheral surface of the shaft member; a first light emitting portion that is stationary relative to the stationary portion and emits light toward the first protrusion portion; a first light receiving portion that receives at least a portion of light that is emitted from the first light emitting portion and reaches an axial range of the shaft member in which the first protrusion portion is provided; an axial displacement detection unit that detects an axial displacement of the shaft member relative to the stationary portion based on the light received by the first light receiving unit; A displacement detection device comprising:

2. a shaft member rotation drive unit that enables rotational displacement of the shaft member relative to the stationary unit; a plurality of second protrusions arranged at intervals in the circumferential direction on the outer peripheral surface of the shaft member; a second light emitting portion that is stationary relative to the stationary portion and emits light toward the second protrusion portion; a second light receiving portion that receives at least a portion of the light that is emitted from the second light emitting portion and reaches a circumferential range of the shaft member in which the second protrusion portion is provided; a circumferential displacement detection unit that detects a circumferential displacement of the shaft member relative to the stationary portion based on the light received by the second light receiving unit; The displacement detection device according to claim 1 , comprising:

3. A stationary portion; A shaft member; a shaft member rotation drive unit that enables rotational displacement of the shaft member relative to the stationary unit; a plurality of protrusions arranged at intervals in the circumferential direction on the outer peripheral surface of the shaft member; a light emitting portion that is stationary relative to the stationary portion and emits light toward the protrusion portion; a light receiving portion that receives at least a portion of the light that is emitted from the light emitting portion and reaches a circumferential range of the shaft member in which the protrusion portion is provided; a circumferential displacement detection unit that detects a circumferential displacement of the shaft member relative to the stationary portion based on the light received by the light receiving unit; A displacement detection device comprising:

4. a step of irradiating light from a first light-emitting unit that is stationary with respect to a stationary portion onto a first protrusion portion of a shaft member that is movable in an axial direction relative to the stationary portion and has a plurality of first protrusion portions on an outer peripheral surface thereof that are spaced apart in the axial direction; detecting an axial displacement of the shaft member relative to the stationary portion based on at least a portion of light that is emitted from the first light-emitting portion and reaches an axial range of the shaft member in which the first protrusion portion is provided; A displacement detection method comprising:

5. the shaft member is movable relative to the stationary portion in a circumferential direction and has a plurality of second protrusions arranged at intervals in the circumferential direction on the outer circumferential surface, irradiating the second protrusion portion with light from a second light-emitting portion that is stationary relative to the stationary portion; detecting a circumferential displacement of the shaft member relative to the stationary portion based on at least a portion of light that is emitted from the second light-emitting portion and reaches the circumferential range of the shaft member in which the second protrusion portion is provided; The displacement detection method of claim 1 , comprising:

6. a step of irradiating light from a light emitting unit stationary with respect to a stationary portion onto a protruding portion of a shaft member that is movable in a circumferential direction relative to the stationary portion and has a plurality of protruding portions arranged at intervals in the circumferential direction on an outer circumferential surface of the shaft member; detecting a circumferential displacement of the shaft member relative to the stationary portion based on at least a portion of light emitted from the light-emitting portion and reaching a circumferential range of the shaft member in which the protrusion portion is provided; A displacement detection method comprising:

7. an output shaft having at least one first pressure-receiving surface, a plurality of first protrusions arranged on an outer peripheral surface at intervals in the axial direction, and a plurality of second protrusions arranged on the outer peripheral surface at intervals in the circumferential direction; a sleeve having an inner circumferential surface portion that supports the output shaft movably in the axial direction, and a second pressure receiving surface that, together with the first pressure receiving surface, defines at least a portion of a pressure chamber; an advance / retract drive unit that varies the volume of the pressure chamber by changing the amount of fluid supplied to the pressure chamber, thereby advancing and retracting the output shaft in the axial direction relative to the sleeve; a rotating portion disposed radially outside the output shaft and rotatably and coaxially with the output shaft; a spring body arranged radially outward of the output shaft and substantially coaxially with the output shaft so as to be extendable and contractible in the axial direction, the spring body having one end fixed to the output shaft and the other end fixed to the rotating unit, the spring body rotating the output shaft in the circumferential direction when the rotating unit is rotationally driven; a first sensor that is stationary with respect to the sleeve and includes a first light-emitting unit that emits light toward the first protrusion, and a first light-receiving unit that receives at least a portion of the light that is emitted from the first light-emitting unit and reaches an axial range of the shaft member in which the first protrusion is provided; an axial displacement detection unit that detects an axial displacement of the shaft member relative to the stationary portion based on the light received by the first light receiving unit; a second sensor that is stationary with respect to the sleeve and includes a second light-emitting unit that emits light toward the second protrusion portion, and a second light-receiving unit that receives at least a portion of the light that is emitted from the second light-emitting unit and reaches a circumferential range of the shaft member in which the second protrusion portion is provided; a circumferential displacement detection unit that detects a circumferential displacement of the shaft member relative to the stationary portion based on the light received by the second light receiving unit; A fluid pressure actuator comprising:

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