JP2018091769A - Displacement detector - Google Patents

Abstract

An object of the present invention is to provide a displacement detection device that can improve the accuracy of detecting an origin position. A displacement detection device 1 includes a light source 11, a hologram lens 17, and a light receiving section 12. The hologram lens 17 is provided on the scale 2 and focuses the light L1 emitted from the light source 11. The light receiving section 12 is provided in the head 3 and receives the light L1 focused by the hologram lens 17. The focal position of the hologram lens 17 is the position where the light receiving section 12 is placed. [Selection diagram] Figure 1

Description

  The present invention relates to a displacement detection device that detects a relative displacement amount of a head and a scale by a non-contact sensor using light emitted from a light source, and more particularly to a displacement detection device that can detect an origin position.

  2. Description of the Related Art Conventionally, a displacement detection device including a scale and a detection head has been widely used as a measuring instrument that performs precise measurement such as linear displacement and rotational displacement. In recent years, a displacement detector using a light emitting diode or laser light has been used. Further, there is a demand for a displacement detection apparatus with a high resolution capable of measuring a displacement of 1 nm or less.

  As a conventional displacement detection device of this type, for example, there is one described in Patent Document 1. In the displacement detection apparatus described in Patent Document 1, a fixed point detection diffraction grating including a first pattern region and a second pattern region is provided on a scale in order to detect a reference position that is an origin position. The head is also provided with a first sensor that receives light diffracted by the first pattern region and a second sensor that receives light diffracted by the second pattern region.

  In the displacement detection device described in Patent Document 1, a differential waveform between the output waveform of the first sensor and the output waveform of the second sensor is acquired, and the midpoint of this differential waveform is recognized as the origin position. .

JP 2008-256655 A

  However, in the conventional displacement detection device described in Patent Document 1, it is necessary to irradiate light across both the first pattern region and the second pattern region at the boundary between the first pattern region and the second pattern region. . As a result, the displacement detection device described in Patent Document 1 has a problem that the spot diameter of light becomes large and it is difficult to increase the detection accuracy of the origin position.

  An object of the present invention is to provide a displacement detection device capable of increasing the detection accuracy of the origin position.

  In order to solve the above problems and achieve the object of the present invention, a displacement detection device of the present invention comprises a scale and a head disposed opposite the scale, and the origin position in the measurement direction relative to the scale in the head is determined. This is a detectable displacement detection device. The displacement detection device includes a light source, a hologram lens, and a light receiving unit. The light source is provided in the head and irradiates light toward the scale. The hologram lens is provided on the scale and collects light emitted from the light source. The light receiving unit is provided in the head and receives light collected by the hologram lens. The focal position of the hologram lens is the position where the light receiving unit is disposed.

  Another displacement detection apparatus of the present invention includes a scale and a head. The displacement detection device includes a light source, a reflection mirror or diffraction grating, a corner cube, a hologram lens, and a light receiving unit. The light source is provided in the head and irradiates light toward the scale. The reflection mirror or the diffraction grating is provided on the scale and reflects light emitted from the light source. The corner cube is provided in the head and reflects the light reflected by the reflecting mirror or the diffraction grating toward the scale again. The hologram lens is provided on the scale and collects the light reflected by the corner cube. The light receiving unit is provided in the head and receives light collected by the hologram lens. The focal position of the hologram lens is the position where the light receiving unit is disposed.

  Furthermore, another displacement detection apparatus of the present invention includes a scale and a head. The displacement detection device includes a light source, a hologram lens, and a light receiving unit. The light source is provided in the head and irradiates light toward the scale. The hologram lens is provided on the scale and collects light emitted from the light source. The light receiving unit is provided in the head and receives light collected by the hologram lens. The head is provided with a light receiving portion for relative position used when detecting the relative position in the measurement direction with respect to the scale. The light receiving unit is disposed at a position where the position in the width direction parallel to the measurement surface of the scale and perpendicular to the measurement direction is the same as the position in the width direction with respect to the scale in the light receiving unit for relative position. ing. Further, the focal position of the hologram lens is the position where the light receiving unit is arranged.

  According to the displacement detection device of the present invention, the detection accuracy of the origin position can be increased.

It is a schematic block diagram which shows the structure of the displacement detection apparatus concerning the 1st Example of this invention. It is explanatory drawing which shows the space | interval of the grating | lattice of the hologram lens of the displacement detection apparatus concerning the 1st Example of this invention. It is a graph which shows the intensity | strength of the light reflected by the hologram lens of the displacement detection apparatus concerning the 1st Example of this invention. It is a top view which shows the hologram lens and scale of the displacement detection apparatus concerning the 1st Example of this invention. It is explanatory drawing which shows the positional relationship of the hologram lens and light-receiving part of the displacement detection apparatus concerning the 1st Example of this invention. It is a block diagram which shows the structure of the control part for the origin detection in the displacement detection apparatus concerning the 1st Example of this invention. It is explanatory drawing which shows the waveform of the signal output by the light-receiving part in the displacement detection apparatus concerning the 1st Example of this invention, and the intensity | strength of the light reflected by the light-receiving part. It is explanatory drawing which shows the case where the scale in the displacement detection apparatus concerning the 1st Example of this invention inclines in the pitch direction. It is explanatory drawing which shows the case where the scale in the conventional displacement detection apparatus inclines in the pitch direction. It is explanatory drawing which shows the case where the scale in the displacement detection apparatus concerning the 1st Example of this invention inclines in the yaw direction. It is explanatory drawing which shows the case where the scale in the displacement detection apparatus by which the light-receiving part is arrange | positioned on the diffraction grating for origin detection inclines in the yaw direction. It is a schematic block diagram which shows the structure of the displacement detection apparatus concerning the 2nd Example of this invention. It is explanatory drawing which shows the case where the scale in the displacement detection apparatus concerning the 2nd Example of this invention inclines in the pitch direction.

Hereinafter, embodiments of the displacement detection device of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the common member in each figure. The present invention is not limited to the following form.
The various lenses described in the following description may be a single lens or a lens group.

1. First embodiment example 1-1. Configuration Example of Displacement Detection Device First, the configuration of a displacement detection device according to a first embodiment (hereinafter referred to as “this example”) will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram illustrating a configuration of a displacement detection device.

  The displacement detection device 1 of this example detects the displacement amount in the first direction X from the origin position when the head and the scale are moved relative to each other in the measurement direction (hereinafter referred to as “first direction X”). It is a device to do. As shown in FIG. 1, the displacement detection device 1 includes a scale 2 and a head 3 that faces the scale 2.

  The scale 2 is a reflective scale that reflects the light emitted from the head 3. The scale 2 is formed in a flat plate shape. On the measurement surface 2 a facing the head 3 in the scale 2, a track for detecting a relative position (not shown) is provided. In addition, a reflection mirror for detecting an origin position, which will be described later, is provided at one end of a width direction (hereinafter referred to as “second direction Y”) that is parallel to the measurement surface 2a of the scale 2 and is orthogonal to the first direction X. 16 and a hologram lens 17 are arranged. A direction orthogonal to the first direction X and the second direction Y, that is, the direction in which the scale 2 and the head 3 face each other is defined as a third direction Z.

  The head 3 is provided with a relative position detection unit that detects a displacement amount in the first direction X using a relative position detection track provided on the scale 2. Further, the head 3 is provided with a light source 11 for detecting the origin position, a light receiving unit 12, a lens 13, and a corner cube 14.

  As the light source 11, for example, a semiconductor laser diode, a super luminescence diode, a gas laser, a solid-state laser, a light emitting diode, or the like can be used. The light source 11 emits light L1 toward one end portion of the scale 2 in the Y direction. A lens 13 is disposed on the side of the light source 11 where the light L1 is emitted.

  The lens 13 is disposed between the light source 11 and the measurement surface 2 a of the scale 2. The lens 13 collimates the light L1 emitted from the light source 11 into parallel light. The light L1 collimated into parallel light by the lens 13 is incident on the measurement surface 2a of the scale 2.

  Light L1 collimated into parallel light by the lens 13 is incident on the reflection mirror 16. The reflection mirror 16 reflects the incident light L1 toward the corner cube 14 provided in the head 3 again.

  In addition, although the example using the reflective mirror 16 was demonstrated in this example, it is not limited to this. For example, when reflecting the light L <b> 1 toward the corner cube 14, if the angle incident from the lens 13 is different from the angle toward the corner cube 14, a diffraction grating may be used instead of the reflection mirror 16. Accordingly, the light L1 incident from the lens 13 can be diffracted and reflected at a predetermined angle, and the light L1 can be incident on the corner cube 14 provided on the head 3 at a predetermined angle.

  The corner cube 14 is an optical component having a first reflecting portion 14a and a second reflecting portion 14b. The first reflecting portion 14a and the second reflecting portion 14b are combined at a substantially right angle. The first reflecting portion 14a and the second reflecting portion 14b reflect the incident light L1. The corner cube 14 emits reflected light in the direction in which the light L1 is incident. The incident angle of the light L1 incident on the corner cube 14 and the reflection angle of the light L1 reflected by the corner cube 14 are equal.

  The corner cube 14 may be constituted by two reflecting mirrors, or a prism or the like may be used.

  The light L1 reflected by the corner cube 14 enters a hologram lens 17 provided on the measurement surface 2a of the scale 2. The hologram lens 17 diffracts the incident light L1 and reflects it toward the light receiving unit 12. The hologram lens 17 is a reflective diffraction grating having a plurality of gratings.

  FIG. 2 is an explanatory diagram showing the lattice spacing of the hologram lens 17 when the hologram lens 17 is cut along the first direction X. Note that the horizontal axis in FIG. The axis indicates the height of the grating of the hologram lens 17.

  As shown in FIG. 2, the center of the hologram lens 17 in the first direction X is set wide as the grating interval. The interval between the lattices becomes narrower as the distance from the center increases to both sides in the first direction X. That is, the grating in the hologram lens 17 becomes sparse as it goes to the center and becomes dense as it goes away from the center.

  FIG. 3 is a graph showing the intensity in the first direction X in the light L <b> 1 reflected by the hologram lens 17. 3 represents the relative position of the scale 2 and the head 3 in the first direction X, and the vertical axis represents the intensity of light reflected by the hologram lens 17. In FIG. FIG. 3 shows an example in which parallel light having a spot diameter of φ1 mm is incident on the hologram lens 17 whose length in the first direction X is 1 mm.

  As shown in FIG. 3, the hologram lens 17 has the highest intensity of reflected light at the center in the first direction X. That is, the hologram lens 17 condenses the incident light L1 at the center in the first direction X by diffracting and reflecting it. In the example shown in FIG. 3, it is possible to obtain reflected light with a spot diameter reduced to about φ4 μm at a focal length of 10 mm.

FIG. 4 is a plan view showing the position of the focal point G of the hologram lens 17 when the light L1 enters the measurement surface 2a of the scale 2 perpendicularly.
As shown in FIG. 4, the hologram lens 17 is obtained by cutting a part of a virtual hologram lens 17 a (hereinafter referred to as “virtual hologram lens”) indicated by a dotted line covering the measurement surface 2 a of the scale 2. Here, the focal point G of the light L1 collected by the virtual hologram lens 17a is arranged on the origin position X1 in the first direction X on the scale 2. The focal point G of the light L1 collected by the virtual hologram lens 17a is arranged on the center line 2b in the second direction Y on the measurement surface 2a of the scale 2. That is, the focal point G of the light L1 collected by the virtual hologram lens 17a passes through the center line 2b of the track on which the scale for detecting the relative position is arranged.

  Here, since the hologram lens 17 is a part of the virtual hologram lens 17a cut out, the focal point G of the light L1 collected by the hologram lens 17 coincides with the virtual hologram lens 17a. Therefore, the focal point G of the light L1 collected by the hologram lens 17 is disposed on the origin position X1 in the first direction X on the scale 2 and on the center line 2b in the second direction Y on the measurement surface 2a. . Further, the hologram lens 17 reflects the incident light L1 toward the light receiving unit 12.

FIG. 5 is an explanatory diagram showing the positional relationship between the light receiving unit 12 and the hologram lens.
As shown in FIGS. 1 and 5, the light receiving unit 12 includes a reflecting member 21, a first light receiving element 22, and a second light receiving element 23. The reflection member 21 is formed in a triangular prism shape. The reflecting member 21 has a first reflecting surface 21a and a second reflecting surface 21b. The reflecting member 21 is arranged with the apex 21 c where the first reflecting surface 21 a and the second reflecting surface 21 b intersect with the scale 2. The first reflecting surface 21 a faces one side in the first direction X, and the second reflecting surface 21 b faces the other side in the first direction X.

  As shown in FIGS. 4 and 5, the reflecting member 21 is disposed so that the vertex 21 c of the reflecting member 21 passes over the origin position X <b> 1 in the first direction X on the scale 2. Furthermore, the vertex 21 c of the reflecting member 21 is disposed on the center line 2 b in the second direction Y on the measurement surface 2 a of the scale 2. Therefore, the focal point G (focal position) of the light L1 collected by the hologram lens 17 coincides with the vertex 21c of the reflecting member 21 in the plane formed in the second direction Y and the third direction Z. Therefore, when the head 3 moves to the origin position X1, the focal point G of the light L1 collected by the hologram lens 17 coincides with the vertex 21c of the reflecting member 21 of the light receiving unit 12. Then, the light L 1 reflected by the hologram lens 17 is incident on the reflecting member 21.

  A light receiving unit 31 (see FIG. 10) for detecting a relative position is arranged on the center line 2b of the scale 2. Therefore, the position in the second direction Y of the reflecting member 21 of the light receiving unit 12 coincides with the position of the second direction Y in the light receiving unit 31 for detecting the relative position.

  As shown in FIGS. 1 and 5, the first light receiving element 22 is arranged on one side of the first direction X in the reflecting member 21, and on the other side of the first direction X in the reflecting member 21. The second light receiving element 23 is arranged. Therefore, the first light receiving element 22 and the second light receiving element 23 are arranged to face each other with the reflecting member 21 interposed therebetween.

  Further, the reflecting member 21 reflects the light L1 incident on the first reflecting surface 21 a toward the first light receiving element 22. The reflecting member 21 reflects the light L1 incident on the second reflecting surface 21b toward the second light receiving element 23. In addition, when the light L1 is incident on the vertex 21c of the reflecting member 21, the reflecting member 21 equally divides the light L1 into two to be directed to the first light receiving element 22 and the second light receiving element 23. Reflect.

  The first light receiving element 22 and the second light receiving element 23 are, for example, photodetectors that convert received light into electricity.

FIG. 6 is a block diagram showing the configuration of the origin detection control unit in the displacement detection apparatus 1.
As shown in FIG. 6, the displacement detection device 1 includes a differential amplifier 24 connected to the first light receiving element 22 and the second light receiving element 23, an A / D conversion unit 25, a waveform correction processing unit 26, and the like. And an absolute position calculation unit 27.

  The signal converted from the light source by the first light receiving element 22 and the second light receiving element 23 is output to the differential amplifier 24. The differential amplifier 24 differentially amplifies signals received from the first light receiving element 22 and the second light receiving element 23. The signal differentially amplified by the differential amplifier 24 is A / D converted by the A / D converter 25 and corrected by the waveform correction processor 26. The signal corrected by the waveform correction processing unit 26 is output to the absolute position calculation unit 27, and the absolute position calculation unit 27 detects the origin position X1.

1-2. Origin Position Detection Operation in Displacement Detection Device Next, the origin position detection operation of the displacement detection device 1 having the above-described configuration will be described with reference to FIGS.
FIG. 7 is an explanatory diagram showing the waveform of a signal output by the light receiving unit 12 and the intensity of the light L1 reflected by the light receiving unit 12. The solid line shown in FIG. 7 indicates the intensity of the light L 1 reflected by the light receiving unit 12, the alternate long and short dash line indicates the signal waveform of the first light receiving element 22, and the dotted line indicates the signal waveform of the second light receiving element 23. Show. A two-dot chain line indicates a signal output from the differential amplifier 24 that is a difference between outputs of the first light receiving element 22 and the second light receiving element 23. In FIG. 7, the horizontal axis indicates the relative position of the scale 2 and the head 3 in the first direction X, and the vertical axis indicates the output intensity of light and signals.

  As shown in FIG. 1, the light L1 emitted from the light source 11 is collimated by the lens 13 to become parallel light. The spot diameter of the light L1 at this time is, for example, φ1 mm. The light L1 collimated into parallel light by the lens 13 enters the reflection mirror 16. The reflection mirror 16 reflects the incident light L1 toward the corner cube 14.

  The corner cube 14 reflects the incident light L1 toward the measurement surface 2a of the scale 2 again. The light L 1 reflected by the corner cube 14 enters the hologram lens 17. The hologram lens 17 condenses the incident light L1. As a result, the spot diameter of the light L1 at the focal point G of the hologram lens 17 is narrowed down to φ40 μm.

  Here, when the head 3 is located on one side of the first direction X with respect to the scale 2 with respect to the scale 2, the light L1 reflected by the hologram lens 17 is reflected as shown in FIG. The light enters the first reflecting surface 21 a of the member 21. The light L1 is reflected by the first reflecting surface 21a and received by the first light receiving element 22.

  Therefore, as shown in FIG. 7, when the head 3 is located on one side in the first direction X with respect to the scale 2, the value of the signal output by the first light receiving element 22. Increases, and the value of the signal output by the second light receiving element 23 decreases.

  When the head 3 is located on the other side in the first direction X with respect to the scale 2, the light L1 reflected by the hologram lens 17 is a reflecting member as shown in FIG. 21 is incident on the second reflecting surface 21b. The light L1 is received by the second light receiving element 23 reflected by the second reflecting surface 21b.

  Therefore, as shown in FIG. 7, when the head 3 is positioned on the other side in the first direction X with respect to the scale 2 from the origin position X1, the value of the signal output by the second light receiving element 23 Increases, and the value of the signal output by the first light receiving element 22 decreases.

  Furthermore, when the head 3 is located at the origin position X1 with respect to the scale 2, the light L1 reflected by the hologram lens 17 enters the vertex 21c of the reflecting member 21, as shown in FIG. The light L <b> 1 is equally divided into two by the reflecting member 21 and is reflected toward the first light receiving element 22 and the second light receiving element 23. For this reason, the light L1 is incident on the first light receiving element 22 and the second light receiving element 23 substantially evenly.

  Therefore, as shown in FIG. 7, the difference between the output signals of the first light receiving element 22 and the second light receiving element 23 is zero. Therefore, the point where the signal differentially amplified by the differential amplifier 24 crosses 0V is detected as the origin position X1.

  According to the displacement detection apparatus 1 of this example, the light L1 is narrowed down by the hologram lens 17 and the focal point is set so that the position where the light receiving unit 12 is disposed is the same position. Thereby, the interval between the points where the signals differentially amplified by the differential amplifier 24 cross 0V can be narrowed, and the detection accuracy of the origin position X1 in the displacement detection device 1 can be increased.

  In addition, although the displacement detection apparatus 1 of this example demonstrated the example which comprised the light-receiving part 12 with the two light-receiving elements 22 and 23 which are a photodetector, and the reflection member 21, it is not limited to this. An optical position sensor (Position Sensitive Detector, PSD) may be used as the light receiving unit 12. And you may make it detect the origin position X1 in the displacement detection apparatus 1 by the change of the voltage of the specific position of an optical position sensor. In this case, the focal point G of the hologram lens 17 is the light receiving surface of the optical position sensor. The output of the optical position sensor at this time corresponds to the output of the differential amplifier 24 described above.

1-3. Inclination Correction Operation of Displacement Detection Device Next, the inclination correction operation of the displacement detection device 1 having the above-described configuration will be described with reference to FIGS.

First, the case where the scale 2 is inclined in the pitch direction, that is, the case where the scale 2 is inclined in the third direction Z by the angle θ will be described with reference to FIGS.
FIG. 8 is an explanatory view showing a case where the scale 2 in the displacement detection device 1 of the present example is inclined in the third direction Z by an angle θ, and FIG. 9 is a conventional displacement without the corner cube 14 and the reflecting mirror 16. It is explanatory drawing which shows the case where the scale 200 of a detection apparatus inclines in the 3rd direction Z by angle (theta).

  As shown in FIG. 9, in the case of the conventional displacement detection device, the light L <b> 1 is emitted from the light source 110 toward the measurement surface 200 a of the scale 200 in parallel with the third direction Z. The light L1 is collimated into parallel light by the lens 130 and is incident on the hologram lens 160. This hologram lens 160 is arranged on the measurement surface 200a of the scale 200 and collects the light L1 as in the displacement detection device 1 of this example.

  In the conventional displacement detection device, when the scale 200 is inclined in the third direction Z by the angle θ, the light L1 incident on the hologram lens 160 is reflected in the state inclined by the angle 2θ with respect to the third direction Z. Is done. Therefore, the light L <b> 1 reflected from the hologram lens 160 is not received by the light receiving unit 120. The difference between the focal positions of the light receiving unit 120 and the hologram lens 160 becomes a detection error of the origin position X1.

  On the other hand, as shown in FIG. 8, the displacement detection device 1 of the present example reflects the light L1 incident on the scale 2 once by the reflection mirror 16, and again the hologram lens 17 of the scale 2 by the corner cube 14. It is made to enter toward. When the light L1 is emitted from the light source 11 in parallel with the third direction Z, the light L1 is reflected by the reflection mirror 16 while being inclined at an angle + 2θ with respect to the third direction Z. That is, the light L1 is incident on the corner cube 14 while being inclined at an angle + 2θ.

  Here, the light L1 is emitted at the same angle as the angle incident on the corner cube 14. Therefore, the light L <b> 1 reflected by the corner cube 14 is emitted from the corner cube 14 in a state tilted at an angle −2θ with respect to the three directions Z. Thereby, the inclination of the scale 2 can be corrected by the corner cube 14. As a result, the light L1 collected by the hologram lens 17 can be reliably incident on the light receiving unit 12, and the detection error of the origin position X1 can be eliminated.

Next, a case where the scale 2 is inclined in the yaw direction with respect to the head 3, that is, a case where an azimuth shift occurs will be described with reference to FIGS.
FIG. 10 is an explanatory diagram showing a case in which the scale 2 is inclined with respect to the head 3 at an angle θ in the yaw direction in the displacement detection device 1 of this example. FIG. 11 is an explanatory diagram showing a case where the scale 2 of the conventional displacement detector is tilted at an angle θ in the yaw direction with respect to the head 3.

  As shown in FIG. 11, in the conventional displacement detection device, the light receiving unit 12 is disposed on a diffraction grating indicating the origin position. That is, in the example shown in FIG. 11, the light receiving unit 12 is disposed on the hologram lens 17, and the light receiving unit 12 is disposed at a position ΔY away from the light receiving unit 31 for detecting the relative position in the second direction Y. The Further, the light receiving unit 12 and the light receiving unit 31 for detecting the relative position are separated from each other in the first direction X by a length T1.

  When the scale 2 is inclined with respect to the head 3 in the yaw direction at an angle θ, the distance between the origin position X1 detected by the light receiving unit 12 and the relative position X0 detected by the light receiving unit 31 for detecting the relative position is the length T1. On the other hand, a deviation of the length ΔY · sin θ occurs.

  On the other hand, as shown in FIG. 10, in the displacement detection device 1 of this example, the light receiving unit 12 is disposed on the center line 2b of the scale 2, and the position of the light receiving unit 12 in the second direction Y is This coincides with the position in the second direction Y in the light receiving unit 31 for detecting the relative position. Therefore, in the displacement detection device 1 of this example, the difference ΔY between the second direction Y between the light receiving unit 12 and the light receiving unit 31 for detecting the relative position is 0 (ΔY = 0). Thereby, even if the scale 2 is inclined with respect to the head 3 in the yaw direction at an angle θ, the origin position X1 detected by the light receiving unit 12 is not displaced. As a result, the interval between the origin position X1 detected by the light receiving unit 12 and the relative position X0 detected by the light receiving unit 31 for detecting the relative position is always a constant interval T1.

2. Second Embodiment Next, a displacement detection device according to a third embodiment will be described with reference to FIGS. 12 and 13.
FIG. 12 is a schematic configuration diagram showing a displacement detection apparatus according to the second embodiment.

  The displacement detector 71 according to the second embodiment differs from the displacement detector 1 according to the first embodiment in that a transmission type scale is used. Therefore, the same code | symbol is attached | subjected to the part which is common in the displacement detection apparatus 1 concerning 1st Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 12, the displacement detection device 71 has a scale 72 and a head 73. The scale 72 is a transmissive scale that transmits incident light. Further, the scale 72 is provided with a scale for detecting the relative position, like the scale 2 according to the first embodiment. Further, the head 73 has a relative position detecting unit for detecting the relative position using a scale for detecting the relative position.

  The head 73 is disposed so as to cover one side and the other side of the scale 72 in the third direction Z. The head 73 includes a light source 81, a lens 83, a reflection mirror 86, and a light receiving unit 82.

  The light source 81, the lens 83, and the light receiving unit 82 are disposed on one side of the scale 72 in the third direction Z. The light L1 emitted from the light source 81 is incident on the scale 72 collimated into parallel light through the lens 83. The light L1 incident on the scale 72 passes through the scale 72 and is emitted to the other side in the third direction Z of the scale 72.

  The reflection mirror 86 is disposed on the other side of the scale 72 in the third direction Z. The reflection mirror 86 reflects the light L1 transmitted through the scale 72 toward the scale 72 again. In addition, although the example using the reflection mirror 86 was demonstrated, you may use a reflection type diffraction grating. Thereby, the angle reflected on the scale 72 can be arbitrarily set by adjusting the diffraction angle.

  Further, a hologram lens 87 is disposed on the scale 72. The hologram lens 87 is a transmissive hologram lens, and diffracts and collects the transmitted light. The focal point G of the hologram lens 87 is set at a position where the light receiving unit 82 is disposed. Light L <b> 1 reflected by the reflecting mirror 86 and transmitted through the scale 72 is incident on the hologram lens 87. Then, the hologram lens 87 causes the light receiving unit 82 to diffract and condense the light L1.

FIG. 13 is an explanatory diagram showing the case where the scale 72 is inclined in the pitch direction, that is, the case where the scale 72 is inclined in the third direction Z at an angle θ.
As shown in FIG. 13, the reflection mirror 86 and the light receiving unit 82 are provided in the head 73, and even if the scale 72 is inclined, the positional relationship between the reflection mirror 86 and the light receiving unit 82 does not change. Therefore, even if the scale 72 is inclined in the third direction Z by the angle θ, the light L1 reflected by the reflecting mirror 86 is transmitted through the scale 72 and the hologram lens 87 and is incident on the light receiving unit 82. As a result, in the displacement detection device 71 according to the second embodiment, the corner cube need not be provided.

  Since other configurations are the same as those of the displacement detection device 1 according to the first embodiment, description thereof will be omitted. Also with the displacement detection device 71 having such a configuration, the same operational effects as those of the displacement detection device 1 according to the first embodiment described above can be obtained.

  The present invention is not limited to the embodiment described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention described in the claims. In the embodiment described above, the light emitted from the light source may be supplied not only in the gas but also in a liquid or vacuum space.

  In addition, the displacement detection device according to the above-described embodiment performs three-dimensional measurement in combination with a rotary encoder in which the diffraction grating rotates in parallel with the plane and a displacement detection device that detects displacement in the height direction. The present invention can be applied to various other displacement detection devices such as a displacement detection device to be performed.

  In this specification, words such as “parallel” and “orthogonal” are used, but these do not mean only strict “parallel” and “orthogonal”, but include “parallel” and “orthogonal”. Further, it may be in a state of “substantially parallel” or “substantially orthogonal” within a range where the function can be exhibited.

  DESCRIPTION OF SYMBOLS 1,71 ... Displacement detection apparatus, 2, 72 ... Scale, 2a ... Measurement surface, 2b ... Centerline, 3, 73 ... Head, 11, 81 ... Light source, 12, 82 ... Light-receiving part, 13, 83 ... Lens, 14 ... corner cube, 14a ... first reflecting part, 14b ... second reflecting part, 16, 86 ... reflecting mirror, 17, 87 ... hologram lens, 17a ... virtual hologram lens, 21 ... reflecting member, 21a ... first reflecting surface, 21b ... second reflecting surface, 21c ... vertex, 22 ... first light receiving element, 23 ... second light receiving element, 24 ... differential amplifier, 27 ... absolute position calculation unit, 31 ... light receiving unit (for relative position detection) , G ... focus, X1 ... origin position

Claims (4)

In a displacement detection device comprising a scale and a head arranged to face the scale, and capable of detecting an origin position in a measurement direction with respect to the scale in the head.
A light source provided on the head and irradiating light toward the scale;
A hologram lens that is provided on the scale and collects light emitted from the light source;
A light receiving portion that is provided in the head and receives light collected by the hologram lens;
The displacement detection device, wherein a focal position of the hologram lens is a position where the light receiving unit is disposed. In a displacement detection device comprising a scale and a head arranged to face the scale, and capable of detecting an origin position in a measurement direction with respect to the scale in the head.
A light source provided on the head and irradiating light toward the scale;
A reflection mirror or a diffraction grating provided on the scale and reflecting light emitted from the light source;
A corner cube provided on the head and reflecting light reflected by the reflecting mirror or the diffraction grating toward the scale again;
A hologram lens that is provided on the scale and collects light reflected by the corner cube;
A light receiving portion that is provided in the head and receives light collected by the hologram lens;
The displacement detection device, wherein a focal position of the hologram lens is a position where the light receiving unit is disposed. In a displacement detection device comprising a scale and a head arranged to face the scale, and capable of detecting an origin position in a measurement direction with respect to the scale in the head.
A light source provided on the head and irradiating light toward the scale;
A hologram lens that is provided on the scale and collects light emitted from the light source;
A light receiving portion that is provided in the head and receives light collected by the hologram lens;
The head is provided with a relative position light receiving unit used when detecting a relative position in the measurement direction with respect to the scale,
The position of the light receiving unit in the width direction parallel to the measurement surface of the scale and perpendicular to the measurement direction with respect to the scale is the same as the position in the width direction with respect to the scale in the light receiving unit for relative position. Placed at the position
The displacement detection device, wherein a focal position of the hologram lens is a position where the light receiving unit is disposed. The scale is provided with a reflection mirror or a diffraction grating that reflects light emitted from the light source,
The head includes a corner cube that reflects the light reflected by the reflecting mirror or the diffraction grating toward the scale again, and a light receiving for relative position that is used when detecting a relative position in the measurement direction with respect to the scale. Part is provided,
The light reflected by the corner cube is incident on the hologram lens,
The position of the light receiving unit in the width direction parallel to the measurement surface of the scale and perpendicular to the measurement direction with respect to the scale is the same as the position in the width direction with respect to the scale in the light receiving unit for relative position. The displacement detection device according to claim 1, wherein the displacement detection device is disposed at a position.

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