JP2005049345A - Optical displacement sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive optical displacement sensor reduced in the number of part items, and easy to be assembled and mounted. <P>SOLUTION: This optical displacement sensor is provided with an interfering light source 1 for emitting a light beam, a scale 3 displaced to traverse the light beam emitted from the interfering light source 1, and formed with a prescribed period of optical pattern 6, and a photodetector 4 mounted with photoreception elements 4-1 having photosensitivity at a fixed period along a scale moving direction for detecting motion of a diffraction interference pattern generated by irradiating the optical pattern 6 with the light beam. A slit plate 2 having a plurality of openings 13 along the scale 3 moving direction is provided on a face from which the light beam of the interfering light source 1 is emitted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical displacement sensor.

  Conventionally, an optical displacement sensor is known as a detection device for a displacement amount of a precision mechanism. An example of the optical displacement sensor is described in, for example, Japanese Patent Application Laid-Open No. 7-55506. FIG. 18 is a diagram showing the configuration of such an optical displacement sensor. A main scale 130 that is a first scale and an index scale 132 that is a second scale are arranged to face each other with a predetermined interval. The main scale 130 and the index scale 132 are formed with optical gratings parallel to each other at the same pitch. The main scale 130 moves relative to the index scale 132 in a direction orthogonal to the optical grating as indicated by arrows.

  The output light of the light emitting diode 133, which is a light source, disposed in front of the main scale 130 is reflected and collimated by the concave mirror 134, and is irradiated to the main scale 130 as parallel light.

  Here, the light emitting diode 133 has three slit openings 131a, 131b, and 131c. These slit openings 131a, 131b, and 131c are arranged in parallel to the optical grating formed on the main scale 130 and the index scale 132, with a predetermined distance from each other.

  A light receiving element 135 such as a phototransistor or a photodiode is disposed behind the index scale 132.

  The light beams emitted from the plurality of slit openings 131a, 131b, and 131c of the light emitting diode 133 are collimated by the concave mirror 134 and irradiated onto the main scale 130. On the other hand, the light beam entering the main scale 130 is diffracted and enters the index scale 132.

  At this time, the arrangement of the slit openings 131a, 131b, and 131c of the light emitting diode 133, the main scale 130, and the index scale 132, the pitch of the optical gratings, and the wavelength λ of the light beam emitted from the light emitting diode 133 are predetermined. When the above relationship is satisfied, a light / dark pattern similar to the optical grating formed on the main scale 130 is projected on the index scale 132.

  Therefore, when the pitch of the optical grating formed on the index scale 132 is configured to be substantially equal to the pitch of the light / dark pattern, the light receiving element 135 has light corresponding to the relative position of the main scale 130 to the index scale 132. Light and darkness of the beam is irradiated, and a signal corresponding to the light and darkness is output from the light receiving element 135 as position information of the main scale 130.

The output signal of the light receiving element 135 is processed by a signal processing circuit 136 so that the relative position of the main scale 131 is obtained.
JP-A-7-55506

  However, such a conventional technique has the following problems. In the case of the conventional example introduced here, the upper electrode of the light emitting diode chip is used as it is as a slit. Therefore, to change the shape of the multiple openings, it is necessary to change the semiconductor process, and changing the multiple openings is a cost. There is a problem that it takes.

  The present invention has been made paying attention to such problems, and an object thereof is to provide a low-cost optical displacement sensor.

  In order to achieve the above object, an optical displacement sensor according to a first aspect of the present invention is a coherent light source that emits a light beam, and is displaced so as to cross the light beam emitted from the coherent light source, and has a predetermined period. And a light-receiving element having photosensitivity at a constant period in a scale moving direction for detecting a movement of a diffraction interference pattern generated by irradiating the optical pattern with the optical beam with a predetermined period. A slit plate having a plurality of openings in the moving direction of the scale is provided on the surface from which the light beam of the coherent light source is emitted.

  According to a second aspect of the present invention, in the optical displacement sensor according to the first aspect of the invention, the coherent light source is a mold light source mounted on a resin member, and the slit plate emits a light beam of the mold light source. Is formed directly on the surface.

  The optical displacement sensor according to a third aspect of the present invention is the optical displacement sensor according to the second aspect, wherein the light beam emitting surface of the mold resin member is surrounded by the front surface, the opposite side is the rear surface, and the front surface and the rear surface are surrounded. If the surface substantially perpendicular to the emission direction of the light beam formed on the side surface is defined as a side surface, a light shielding member is formed on the surface excluding the slit portion on the surface and part or all of the side surface.

  According to a fourth aspect of the present invention, there is provided a coherent light source mounted with a mold that emits a light beam, and an optical pattern having a first predetermined period and a second optical pattern that is displaced across the light beam emitted from the coherent light source. And a light receiving element having photosensitivity at a constant period in a moving direction of the scale for detecting a movement of a diffraction interference pattern generated by irradiating the first optical pattern with the light beam. An optical detector comprising: a first photodetector mounted with an element; and a second photodetector for detecting a light beam pattern generated by irradiating the second optical pattern with the light beam. A displacement sensor that forms a light beam that is applied to the first optical pattern on the mold surface on the side from which the light beam of the coherent light source is emitted, and that is duplicated in the moving direction of the scale. A first slit having an opening, and a second slit forming a light beam irradiated onto the second optical patterns are provided.

According to a fifth aspect of the present invention, in the optical displacement sensor according to the fourth aspect of the present invention, a surface on which the plurality of openings of the first slit are formed, and a surface on which the first optical pattern of the scale is formed. Z1 is the distance between the surface of the scale on which the first optical pattern is formed and the surface on which the light receiving element of the first photodetector is formed, and the first is formed on the scale. In the optical pattern of the predetermined period, the period in the scale movement direction is p1, and the pitch of the plurality of openings in the scale movement direction formed in the first slit is pst.
pst is approximately represented by the formula p1 × (z1 + z2) / z2.

  The sixth invention is the optical displacement sensor according to the fourth invention, wherein the plurality of openings of the first slit and the opening of the second slit are the plurality of openings of the first slit and the opening of the first slit. In the plane where the opening of the second slit is formed, the second slit is formed by shifting a predetermined distance in a direction substantially perpendicular to the moving direction of the scale.

  The seventh invention is the optical displacement sensor according to the sixth invention, wherein the plurality of openings of the first slit and the opening of the second slit are the plurality of openings of the first slit and the opening of the first slit. In the plane in which the opening of the second slit is formed, it is formed so as to overlap at least partly after being shifted by a predetermined distance in a direction substantially perpendicular to the moving direction of the scale. .

  Further, an eighth aspect of the present invention is a coherent light source that emits a light beam, a scale that is displaced across the light beam emitted from the coherent light source, and on which an optical pattern having a predetermined period is formed, and the light beam. A photodetector equipped with a light receiving element having photosensitivity at a constant period in a scale moving direction for detecting the movement of the diffraction interference pattern generated by irradiating the optical pattern with the predetermined period, and the coherent light source An optical displacement sensor comprising a slit plate in which a light beam emitted is arranged on an optical path toward the scale and a plurality of openings are formed in a moving direction of the scale, wherein the slit plate has the plurality of openings. The upper surface or the lower surface of the portion where the light receiving element is formed and the light receiving surface of the light receiving element are fixed to the same plane as the surface on which the light receiving element is formed. Optical displacement sensor.

According to a ninth invention, in the optical displacement sensor according to any one of the first, third, and eighth inventions, the surface on which the plurality of openings of the slit are formed and the optical pattern of the scale are formed. The distance between the surface is z1, the distance between the surface on which the optical pattern of the scale is formed and the formation surface of the light receiving element having photosensitivity in a constant period in the scale moving direction of the photodetector is z2, and the scale in the scale When the period of the optical pattern in the moving direction is p1, and the pitch of the plurality of openings in the scale moving direction in the slit is pst,
pst is represented by an equation of approximately p1 × (z1 + z2) / z2.

  According to a tenth aspect of the present invention, in the optical displacement sensor according to any one of the first, fourth, fifth, sixth, seventh, eighth, and ninth aspects, the light source side surface of the slit plate is subjected to an antireflection treatment. It has been subjected.

  According to an eleventh aspect of the present invention, in the optical displacement sensor according to any one of the first, fourth, and tenth aspects, the coherent light source includes a lens that controls the spread of the light beam at the light beam emitting portion, and a slit. And a flat surface capable of fixing the plate parallel to the scale surface.

  According to a twelfth aspect of the invention, in the optical displacement sensor according to the eleventh aspect of the invention, when the slit plate is disposed above the coherent light source, the lens is formed below the flat surface. ing.

  According to a thirteenth aspect, in the optical displacement sensor according to the eleventh aspect, the lens is a planar optical element such as a Fresnel lens.

  The present invention provides a low-cost optical displacement sensor that reduces the number of parts and facilitates assembly and mounting.

    Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of an optical displacement sensor as an optical displacement sensor according to the first embodiment of the present invention. The optical displacement sensor includes a scale 3 that is fixed to a member such as a stage that detects displacement, and a sensor head 200 that detects the displacement of the scale 3.

  The scale 3 is supported so as to be able to move across the light beams emitted from the openings of the plurality of openings 13 of the slit plate 2 described later, and an optical pattern 6 having a predetermined period for diffracting or reflecting the light beams is formed. Yes.

  On the other hand, the sensor head 200 has a plurality of coherent light sources 1 that irradiate the scale 3 with a light beam on the sensor substrate 100 and a plurality of openings in the moving direction of the scale 3 provided on the surface from which the light beam of the coherent light source 1 is emitted. And a light receiving element having photosensitivity at a constant period in a scale moving direction for detecting a diffraction interference pattern generated by irradiating the optical pattern 6 of the scale 3 with the light beam. And a photodetector 4 constituted by 4-1.

  First, the detection principle in the present embodiment will be described.

  The wavelength λ of the light source, the pitch pst of the plurality of openings in the slit, the scale pitch p1, the distance between the surface on which the plurality of openings are formed and the surface on which the optical pattern of the scale is formed, z1, and the surface on which the optical pattern of the scale is formed When the distance from the formation surface of the light receiving element having photosensitivity at a constant period in the direction of the scale movement of the photodetector is z2, it is formed on the scale on the photodetector when the following equation is satisfied. A diffraction interference pattern having a period p2 similar to the periodic pattern is formed.

(1 / z1) + (1 / z2) = λ / (n (p1) ² ) (1)
p2 = p1 × (z1 + z2) / z1 (2)
pst = p1 × (z1 + z2) / z2 (3)
Here, n is a natural number. In the present embodiment, the `` light receiving element having photosensitivity at a constant period in the scale moving direction '' is composed of an array of light receiving elements formed at a constant period in the scale moving direction.
In the present embodiment, the arrayed light receiving elements on the photodetector are arranged at a period p2 expressed by the equation (2), and the pitch of the plurality of openings of the slit is set to pst expressed by the equation (3). Thus, it becomes possible to detect the movement of the diffraction interference pattern. That is, when the coherent light source, the scale, and the array-shaped light receiving element are in the arrangement represented by the formula (2), the pitch of the plurality of openings of the slit is set to pst represented by the formula (3), thereby A diffraction interference pattern is formed on the light receiving element. Furthermore, in this case, by setting the pitch of the array-shaped light receiving element in the scale moving direction to p2 expressed by the equation (2), the diffraction interference pattern formed on the light receiving surface of the array-shaped light receiving element and the light receiving element Since the pitches match, the array-shaped light receiving element can detect the light intensity for each specific phase of the diffraction interference pattern, so that the movement of the diffraction interference pattern accompanying the movement of the scale can be detected.

  The coherent light source 1 is a mold light source mounted on a plane on the sensor substrate 100, and a slit plate 2 having a plurality of openings is directly fixed to the surface on the light emission side. The pitch direction of the plurality of openings of the slit plate 2 is substantially parallel to the pitch direction of the optical pattern 6 having a predetermined period on the scale 3. The periphery of the light emitting surface of the coherent light source 1 other than the openings of the plurality of openings 13 is covered with a light absorbing resin 10 in order to prevent light leaked from entering the photodetector 4 directly.

  Reference numerals 103 and 104 denote electrode plates that serve both as electrical connection and fixation of the coherent light source 1.

  In FIG. 1, p <b> 1 is a period in the moving direction of the scale 3 of the optical pattern 6 formed on the scale 3. Since the period of the diffraction interference pattern on the light receiving portion 4-1 of the array-shaped light receiving element of the photodetector 4 is p2, the arrangement pitch of the light receiving portions 4-1 is also set to p2. Z1 is the distance between the surface of the slit plate on which the plurality of openings 13 are formed and the surface on which the optical pattern of the scale 3 is formed, and z2 is the surface of the optical pattern 6 of the scale 3 and the photodetector 4. This is the distance from the light receiving portion 4-1 of the array-shaped light receiving element formed above.

  Further, pst is a pitch in the moving direction of the scale 3 in the plurality of openings 13 of the slit plate.

  Further, a plurality of array-shaped light receiving element groups are provided, and the diffraction interference patterns are electrically connected by being grouped with each other at a pitch p2 so as to receive phase portions whose phases are different from each other by 90 degrees. It is desirable to form four array-like light receiving element groups (A +), (B +), (A−), and (B−) that are shifted in the moving direction at intervals of p2 / 4.

(In FIG. 1, for the sake of simplicity, only one group of light receiving elements in the form of an array is shown.)
From four output signals (A +), (B +), (A-), (B-) detected by each group of a plurality of array-shaped light receiving elements and having a phase difference of 90 degrees, VA = (A +) -(A-) and VB = (B +)
When-(B-) is obtained, components due to light having no periodic components such as external light can be canceled, so that it is possible to output two signals, VA and VB, in which the influence of noise or the like is canceled.

  A Lissajous figure can be obtained by displaying these two signals VA and VB in XY.

This Lissajous figure is circular, and a point on the Lissajous figure indicates the current position. When this point makes one rotation of the Lissajous circle, it corresponds to the movement p1 of one pitch of the scale 3.

  Here, by interpolating this Lissajous figure, it is also possible to detect a movement amount smaller than one pitch of the optical pattern 6.

  Next, features of the optical displacement sensor in the embodiment will be described.

  In the optical displacement sensor according to the present embodiment, the slit plate 2 is directly attached or formed on the mold surface of the light-emitting diode mounted by mold mounting. With this configuration, it is possible to easily change the pitch of the plurality of openings and provide a small-sized and low-cost optical displacement sensor.

(Second Embodiment)
Next, an optical displacement sensor according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a diagram showing a configuration of the optical displacement sensor, and FIG. 3 is a cross-sectional view of a central portion thereof. Detailed description of the same parts as those of the first embodiment will be omitted.

  Next, a specific configuration of the present embodiment will be described. Here, the slit direction with respect to the sensor substrate 100 is assumed to be “upward”.

  The slit plate 2 has a plurality of openings formed in the moving direction of the scale 3 disposed above the coherent light source 1, and the slit plate 2 further includes a light receiving surface of the photodetector 4 and a plurality of openings 13 of the coherent light source 1. Are fixed to the upper surface of the photodetector 4 and are disposed above the coherent light source so that the aperture surfaces of the first and second apertures are in the same plane. The slit plate 2 has a slit opening formed of a chromium thin film on a glass substrate, and the slit plate 2 has a plurality of openings 13 formed on a surface facing the coherent light source 1. The light beam emitted from the coherent light source 1 is irradiated to the periodic pattern 6 of the scale 3 through a plurality of openings 13 formed on the slit plate 2. The light beam reflected and diffracted by the scale 3 forms a diffraction interference pattern on the photodetector 4.

At this time, the plurality of openings 13 formed on the slit plate 2 are formed on the same plane as the surface facing the coherent light source 1, that is, the surface attached to the photodetector 4 of the slit plate 2. Z1 and z2 are automatically made substantially equal without using a special jig or the like and without special adjustment. Thereby, according to the equations (2) and (3),
pst = p2 = 2 × p1 (4)
Is derived.

  Accordingly, with this configuration, the pitch pst of the plurality of openings on the slit plate and the light and dark pitches of the diffraction interference pattern formed on the photodetector do not depend on the distances z1 and z2, and are both fixed to 2p1. When pst = p2 = 2p1) is used, stable detection is possible even if the distance z1 (= z2), that is, the gap between the sensor head and the scale fluctuates.

Furthermore, since the relationship of z1 = z2 is preserved during design and manufacturing, it is possible to set the opening pitch pst of a plurality of openings without depending on the mounting tolerance of the gap between the scale and the sensor head.

  When the thickness of the light source 1 is thicker than that of the photodetector 4, it is possible to adjust the height by attaching the height adjusting member 11 on the sensor substrate 100.

  With this configuration, it is possible to provide a sensor head that is extremely easily and cost-effective and is not easily affected by gap changes.

(Third embodiment)
Next, an optical displacement sensor according to a third embodiment of the present invention will be described with reference to FIG. Detailed description of the same parts as those of the second embodiment will be omitted.

  In the present embodiment, the slit plate 2 has a plurality of openings 13 and a region excluding the light receiving portion of the photodetector as a light shielding portion. A light blocking member 10 that does not transmit the light beam emitted from the coherent light source 1 is also disposed between the coherent light source 1 and the photodetector 4. With this configuration, it is possible to prevent the light beam emitted from the coherent light source 1 from being directly irradiated onto the photodetector 4. This makes it difficult to irradiate the light detector with a light beam other than the signal component, so that it is possible to reduce an adverse effect of such a light beam on a detection signal or the like.

  Also in this embodiment, the formation surface of the plurality of openings 13 of the slit plate 2 is formed on the surface facing the coherent light source 1, that is, the surface attached to the photodetector 4, the light receiving surface of the photodetector. Therefore, since z1 and z2 are always equal, there is an advantage that the bright and dark pitch of the diffraction interference pattern formed on the photodetector does not depend on the gap between the scale and the sensor head.

  By adopting such a configuration, it is possible to realize a sensor head that is not easily affected by light beams other than signal components and that is not easily affected by gap changes.

(Fourth embodiment)
Next, an optical displacement sensor according to a fourth embodiment of the present invention will be described with reference to FIG. Detailed description of the same parts as those of the first embodiment will be omitted.

  FIG. 5 is a diagram showing a configuration of an optical displacement sensor according to the fourth embodiment of the present invention. The coherent light source 1 is a light source mounted on a stem that is generally commercially available. The coherent light source 1 is mounted on the mounting substrate 101 so that the position of the light beam emitting portion of the light source 1 is as low as possible. The slit plate 2 is directly fixed to the flat sealing glass surface of the light beam emitting surface of the coherent light source 1 mounted on the stem.

  The coherent light source 1 mounted on the stem has a light beam emission spread angle controlled, and leaked light is shielded by a cap 40 for sealing the stem. In addition, the operation reliability of the coherent light source 1 is very high and low in price, and when the distance between the scale 3 and the sensor head 100 is sufficient, a high-resolution and low-cost displacement sensor can be realized.

(Fifth embodiment)
FIGS. 6A and 6B are diagrams showing the configuration of an optical displacement sensor according to the fifth embodiment of the present invention. Detailed description of the same parts as those of the first embodiment will be omitted.

  The coherent light source 1 used in the present embodiment is a light source mounted in a mold, and a slit plate 2 is directly fixed to the light beam emission surface. The slit plate 2 is formed with a periodic pitch pst of a plurality of openings 13 and a second slit 15 having a single opening as shown in FIG. 6B. The pitch direction of the plurality of periodic openings 13 is arranged substantially parallel to the pitch direction of the optical pattern 6 having a predetermined period on the scale 3. The plurality of openings 13 and the second slits 15 of the first slit of the slit plate 2 are formed on the surface facing the coherent light source 1. Except for the openings 13 of the first slits and the openings of the second slits 15 and around the light emitting surface of the coherent light source 1, the leak light of the light beam is the first photodetector 4 and the second light detector 2. In order to prevent direct incidence on the light detector 5, it is covered with a light absorbing resin 10.

  A part of the light beam emitted from the coherent light source 1 is irradiated to the periodic pattern 6 formed on the scale 3 through the first plurality of openings 13, and reflected and diffracted by the periodic pattern 6. A diffraction interference pattern is formed on the first photodetector 4. Thereby, the movement of the scale 3 can be detected. Similarly, another part of the light beam emitted from the coherent light source 1 passes through the second slit 15 and irradiates the reference position pattern 7 formed on the scale 3 and is reflected by the reference position pattern 7. The light beam thus made enters the second photodetector 5. As a result, the reference position of the scale 3 can be detected.

  With this configuration, it is possible to easily provide an optical displacement sensor that can detect the movement amount and the reference position of the scale 3 with a simple configuration at low cost.

(Sixth embodiment)
Next, an optical displacement sensor according to a sixth embodiment of the present invention will be described with reference to FIG.

Detailed description of the same parts as those of the first embodiment will be omitted. FIG. 7 is a view showing a light source portion of an optical displacement sensor according to the sixth embodiment of the present invention.

  Here, any one of a metal thin film, a dielectric thin film, a light-absorbing resin thin film, or the like is used on the light emitting side surface of the coherent light source 1 mounted in a mold, and the plurality of openings 13 of the first slit and the second slit Are formed directly on the surface of the coherent light source 1 mounted with a mold. At this time, the plurality of first slits 13 and the second slits 15 may be formed only in the upper planar portion of the mold member from which the light beam is emitted. In order to reduce the adverse effect of the light beam emitted from the region other than the opening 13 and the opening 15 of the second slit, the light beam emitting surface is the front surface of the mold surface of the resin member, the opposite side is the rear surface, the front surface and the rear surface. If the surface substantially perpendicular to the emission direction of the light beam formed so as to surround is defined as the side surface, the light shielding member 10 is integrally formed on the surface excluding the slit portion of the surface and part or all of the side surface.

  Since this light shielding member can significantly reduce the light beam that does not contribute to the diffraction interference pattern formed on the photodetector, it is possible to suppress the DC level of the output signal of the photodetector, and the detection signal Saturation of the signal is suppressed and signal detection with an optimum gain becomes possible.

  In the formation of the slit openings, it is possible to form the plurality of openings 13 of the first slit and the opening 15 of the second slit with high manufacturing accuracy by using a semiconductor patterning technique. Further, by attaching a resin member, an etching member, or the like to the mold surface, a plurality of openings can be easily formed on the mold light source at a low cost. Further, it is possible to integrally pattern a phase grating or the like on the mold member.

  By using such a light source, it is possible to reduce the number of parts when assembling the optical displacement sensor, and to provide an optical displacement sensor that is easier to assemble and less expensive.

(Seventh embodiment)
Next, an optical displacement sensor according to a seventh embodiment of the present invention will be described with reference to FIGS. 8A and 8B are views showing a light source portion of an optical displacement sensor according to the seventh embodiment of the present invention.

  The light source 1 is a mold-mounted and integrated optical element a having a lens, and has a spherical surface shape. The coherent light source 1 is entirely covered with a mold-like cover including a slit plate 2 as shown in the figure. A plurality of first slit openings 13 and second slit openings 15 are formed in the mold-shaped cover, and light beams passing through the first slit plural openings 13 and the second slit openings 15 are respectively scaled. 3 are irradiated on the optical patterns corresponding to each other. At this time, in order to reduce the influence of the leakage light around the light source 1, the light shielding member 10 is filled around the lens. Since this light shielding member can significantly reduce the light beam that does not contribute to the diffraction interference pattern formed on the photodetector, it is possible to suppress the DC level of the output signal of the photodetector, and the detection signal Saturation of the signal is suppressed and signal detection with an optimum gain becomes possible.

The power supply electrode of the light source 1 mounted in a mold leaves a space where wire bonding or the like can be performed without applying a cover.

  By making the slit plate 2 horizontal to the mounting substrate, it is possible to define the distance from the openings of the plurality of openings 13 of the first slit to the surface of the scale 3 as the distance from this plane to the scale 3. Become.

  By controlling the spread of the light beam by the optical element a, it becomes possible to efficiently guide the light beam emitted from the light emitting diode chip to the plurality of openings 13 of the first slit and the opening 15 of the second slit. The light beam can be used efficiently, and the power consumption can be reduced. In addition, the intensity of the output signal can be increased.

(Eighth embodiment)
Next, an optical displacement sensor according to an eighth embodiment of the present invention will be described with reference to FIGS. 9A and 9B are cross-sectional structural views of the light source portion of the optical displacement sensor according to the eighth embodiment of the present invention. The mold light source 1 mounted in a mold on a resin member is integrated by a lens-shaped optical element a made of the same resin member to control the spread of the light beam.

(Eighth embodiment)
This embodiment is an improved type of the seventh embodiment, and a description common to this is omitted.

  In the present embodiment, the lens a formed on the upper surface of the mold member on which the coherent light source 1 is mounted is formed so as to be embedded in the mold member, and a flat region is formed around the lens by the mold member. ing. The slit plate 2 is fixed in this flat region.

By comprising in this way, it becomes possible to fix the slit board 2 flatly on a light source, without using a special member.

(Ninth embodiment)
Next, an optical displacement sensor according to a ninth embodiment of the invention will be described with reference to FIG.

FIG. 10 is a sectional structural view of a light source portion of an optical displacement sensor according to the ninth embodiment of the present invention. Note that detailed description of the same parts as those in the eighth embodiment is omitted here.

  Here, the focal length of the optical element a is set to a predetermined size, and the distance from the lens to the slit plate 2 is set to a predetermined distance, so that the beam spot diameter b formed on the back surface of the slit plate 2 is set to the mold light source 1. It is possible to suppress the spread on the inner side of the depression on the light beam emission surface.

  In this way, by controlling the spread of the light beam by the optical element a so that the spread of the light beam is approximately the same as the multiple opening region of the slit, the multiple openings 13 and the second slit openings 15 of the respective first slits of the slit plate 2. The light beams that have passed through are efficiently irradiated onto the optical pattern and the reference position detection pattern having a predetermined period on the scale.

(Tenth embodiment)
Next, an optical displacement sensor according to a tenth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a diagram showing the structure of the light source of the optical displacement sensor according to the eleventh embodiment of the present invention. Here, detailed description of the same parts as those in the ninth embodiment is omitted.

  When the radius of curvature of the optical element is reduced and the distance from the front end of the convex lens to the surface of the plurality of openings 13 facing each other is set to a predetermined distance, the beam spot diameter on the back surface of the slit plate 2 with respect to the lens dimension 50b. 50a can be suppressed to be spread more inside than the plurality of openings on the module surface. 21 and 22 are drive electrodes of the light emitting diode.

  By applying a low reflection coating to the surface of the plurality of openings 13 of the slit facing the light source 1, fluctuations in the light output of the light source 1 due to return light from the slit plate surface can be suppressed. As a result, it is possible to efficiently irradiate the optical pattern on the scale with a light beam controlled to have the same extent as the plurality of aperture regions of the slit.

(Eleventh embodiment)
Next, an optical displacement sensor according to an eleventh embodiment of the present invention will be described with reference to FIGS. 12A and 12B are views showing the structure of the light source of the optical displacement sensor according to the eleventh embodiment of the present invention.

The coherent light source 1 is attached by a light source mounting board 71 and a frame-shaped light source mounting member (hereinafter referred to as a frame) 60 around the light source mounting board 71. On the light source mounting substrate 71, electrode patterns 53 and 54 are provided at positions corresponding to the electrode patterns on the back surface of the coherent light source 1 that is mold-mounted. In the present embodiment, the thickness of the frame 60 is such that a plurality of openings are formed on the surface of the slit plate 2 facing the coherent light source 1, so that the height of the light source 1 mounted in a mold and the dimensions of the frame 60 are substantially the same. It is formed to do. When a plurality of openings are formed on the surface facing the scale 3, the frame 60 needs to be formed so that the height of the frame 60 substantially coincides with the combined height of the coherent light source 1 and the slit plate 2 mounted on the mold. There is.

  After the frame 60 is fixed to the light source mounting substrate 71, the coherent light source 1 is dropped into the frame 60, and the slit plate 2 is fixedly mounted on the surface of the coherent light source 1 and the surface of the frame 60. The frame 60 can be mounted parallel to the scale moving direction, and the position direction position of the frame 60 can be used as a reference for fixed mounting of the coherent light source 1 and the slit plate 2.

(Twelfth embodiment)
Next, an optical displacement sensor according to a twelfth embodiment of the present invention will be described with reference to FIGS. FIGS. 13A to 13C are views showing the structure of a coherent light source of the optical displacement sensor according to the twelfth embodiment of the present invention.

  The coherent light source here includes a digging region 71 and a light source mounting member 70 having a planar region around the digging region 71. The digging depth is such that the semiconductor bare chip-like coherent light source 1 and the light beam are emitted. It is set to be the same as or deeper than the slit plate 2 fixed directly on the surface of the semiconductor.

  A first electrode pattern 53 is provided from the digging bottom region 71 to the top region. The other end facing this is digged vertically and at least this vertical surface is electrically insulated or highly resistive. A second electrode pattern 54 is provided on the upper surface of the light source mounting member 70 adjacent to the vertical surface.

The semiconductor bare chip coherent light source 1 is mounted on the vertical surface, and the slit plate 2 is directly removed except for the surface electrode in the vicinity of the vertical surface so as to cover the surface from which the light beam of the semiconductor bare chip coherent light source 1 is emitted. Attached to the chip surface and the upper surface of the mounting member. The surface electrode 54 on the vertical surface side is not connected to the bare chip, and then the electrode solder material is connected to the electrode pad on the surface and wired.

  According to the present embodiment, the parallelism between the light source mounting member 70 and the surface of the slit plate 2 can be ensured, and mounting when the semiconductor bare chip-shaped coherent light source 1 is dropped into the digging bottom region 71 is easy. Furthermore, it is possible to suppress a decrease in light source output due to wiring wires, and handling of wires becomes free.

(13th Embodiment)
Next, an optical displacement sensor according to a thirteenth embodiment of the present invention is described with reference to FIG. FIG. 14 is a diagram showing the structure of the light source of the optical displacement sensor according to the thirteenth embodiment of the present invention.

The mounting substrate 101 of the coherent light source 1 is provided with fitting members 55 and 56 that fit into the shape of the coherent light source 1 that is molded and mounted. The mounted coherent light source 1 can be abutted and easily mounted on the sensor substrate 100.

  The fitting members 55 and 56 are connected to the pattern electrode 100-1 on the sensor substrate 100 by a conductor. The conductor shape of the fitting members 55 and 56 matches the shape of the notch 25 of the surface electrode portion of the coherent light source 1 mounted in a mold. The fitting members 55 and 56 are provided perpendicular to the sensor substrate 100, and their tips are flat surfaces, and the slit plate 2 is fixed to the flat surfaces.

The coherent light source 1 mounted in a mold is abutted against the fitting portions of the fitting members 55 and 56 and fixed in accordance with the electrode pattern on the back surface. Thereafter, the notch patterns 26 and 27 formed on the surface of the slit plate 2 and the tip positions and shapes of the fitting members 55 and 56 are fixed to the light beam emission surface portion of the coherent light source 1 and fixed. Accordingly, the light source portion of the optical displacement sensor of the present invention can be easily mounted.

In addition, by using a semiconductor Si substrate as the mounting substrate, it is possible to integrate a photodetector in a predetermined region around the coherent light source mounting portion. The positions of the combined members 55 and 56 can be formed by a semiconductor process patterning technique, and the arrangement control of the light source and the opening of the slit plate and the photodetector becomes easy.

(14th Embodiment)
Next, an optical displacement sensor according to a fourteenth embodiment of the present invention will be described with reference to FIGS. FIGS. 15A and 15B are views showing the structure of the light source of the optical displacement sensor according to the fourteenth embodiment of the present invention.

The mounting substrate 62 of the coherent light source 1 is provided with fitting members 59 and 60 that fit into the shape of the coherent light source 1 that is molded and mounted. The coherent light source 1 can be abutted against the mounted light source 1 so that the coherent light source 1 can be easily mounted on the mounting substrate 62.

  The fitting members 59 and 60 are connected to the pattern electrodes on the mounting substrate 62 by a conductor.

The fitting members 59 and 60 have a conductor shape in which a part of the opposite end portion of the surface electrode portion of the coherent light source 1 mounted in a mold is cut out to form the notches 61 and 62, and the coherent light source 1 is located at this position. It is easy to place and fix. The fitting members 59 and 60 are provided perpendicular to the mounting substrate 62. On the surface of the slit plate 2, alignment patterns 57 and 58 that match the shape of the opposite ends of the coherent light source 1 are provided.

The coherent light source 1 mounted in a mold is abutted against the fitting portions of the fitting members 59 and 60 and fixed in accordance with the electrode pattern on the back surface. Thereafter, the alignment pattern 57, 58 formed on the surface of the slit plate 2 and the cutouts 61, 62 of the fitting members 59, 60 are aligned and fixed, so that the light beam emission surface of the light source 1 is fixed. Attach the slit plate 2 to the part. In this way, the light source with the slit plate can be easily mounted.

(Fifteenth embodiment)
Next, an optical displacement sensor according to a sixteenth embodiment of the invention will be described with reference to FIGS. 16A and 16B are views showing the structure of the light source of the optical displacement sensor according to the fifteenth embodiment of the present invention.

  A plurality of openings 13 having a predetermined period are provided on the back surface of the slit plate 2, and the periphery thereof is a dark part pattern that absorbs light. However, the notch patterns 26 and 27 provided for alignment with the coherent light source 1 mounted in a mold form openings.

In addition, the back surface of the slit plate 2 is subjected to a low reflection coating to suppress the reflected light from returning to the coherent light source 1 and changing the light output of the coherent light source 1.

After the slit plate 2 is fixed to the surface on which the light beam of the coherent light source 1 mounted by the mold is emitted by using the notch patterns 26 and 27, the light beam leakage light is directly input to the detector. In order to suppress, the periphery of the light beam emitting surface of the mold light source is covered with the light absorbing resin 10.

  Thus, the light source and the slit plate of the coherent light source part of the optical displacement sensor of the present invention can be easily mounted.

(Sixteenth embodiment)
Next, an optical displacement sensor according to a seventeenth embodiment of the present invention will be described with reference to FIGS. 17A and 17B are views showing the structure of the light source of the optical displacement sensor according to the sixteenth embodiment of the present invention.

Detailed description of the same parts as those in the fifteenth embodiment will be omitted.

  The back surface of the slit plate 2 is provided with a plurality of openings 13 of the first slit having a predetermined opening period and a second slit opening 15 so as to partially overlap the plurality of openings 13 of the first slit plate. The surrounding area is a dark part pattern that absorbs light. However, the patterns 57a, 57b, 58a, 58b provided for alignment with the coherent light source 1 are openings. The patterns 57a, 57b, 58a, and 58b coincide with the electrode positions at the four corners of the surface of the coherent light source 1 that is mold-mounted.

  Here, since the opening 15 of the second slit overlaps a part of the formation region of the plurality of openings 13 of the first slit, the light beam that has passed through the opening 15 of the second slit is the reference position on the scale. The detection pattern is irradiated. The light beam reflected by this reference position detection pattern is incident on the second photodetector 5 and the reference position is detected.

At the same time, a part of the light beam that has passed through the opening 15 of the second slit is also applied to the first periodic pattern 6 on the scale. By detecting a part of the light beam reflected by the first periodic pattern on the scale by the first photodetector, the movement amount detection signal and the reference position detection signal can be synchronized.

  In addition, since the light beam that has passed through the plurality of openings 13 of the first slit has a wide beam spread with respect to the scale movement direction, a signal corresponding to the reference position detection pattern on the scale can be obtained also by the second photodetector. . On the other hand, the light beam that has passed through the aperture 15 of the second slit having a single aperture used for detecting the reference position is irradiated to the reference position detection pattern on the scale, reflected, and reflected by the second photodetector. The pattern generated above is detected by a second photodetector.

In the present embodiment, utilizing the fact that the reference position signal level detected at this time increases sharply, the opening area of the second slit is extended to the opening portion of the first slit, so that the reference position is The amount of light to the reference position detection pattern on the scale for detection is secured to increase the signal level so that the reference position can be reliably detected.

  As a result, the detection of the reference position becomes clear, and the absolute displacement amount from the reference position can be detected by synchronizing with the relative displacement amount.

(Appendix)
The invention having the following configuration is extracted from the specific embodiment described above.

1. A coherent light source that emits a light beam;
A scale that is displaced across the light beam emitted from the coherent light source and on which an optical pattern having a predetermined period is formed;
A photodetector equipped with a light receiving element having photosensitivity at a constant period in a scale moving direction for detecting the movement of the diffraction interference pattern generated by irradiating the optical pattern with the light beam with the predetermined period;
An optical displacement sensor comprising:
An optical displacement sensor characterized in that a slit plate having a plurality of openings in the moving direction of the scale is provided on a surface from which the light beam of the coherent light source is emitted.

(Corresponding Embodiment of the Invention)
The embodiment relating to the present invention corresponds to at least the first to third and fifth to twelfth embodiments.

(Function and effect)
Here, the coherent light source is a light receiving device having light sensitivity at a constant cycle in the scale movement direction when a light beam emitted alone or in combination with a slit is irradiated on the scale in the arrangement shown in the configuration of this patent. A coherent light source capable of forming a scale diffraction pattern on the element surface, specifically, a light emitting diode (LED), a super luminescent diode (SLD), an edge emitting laser (LD), a surface emitting laser (SEL) etc. shall be pointed out.

  In addition, slits can be selected from those with multiple openings or single openings patterned on the surface with a metal thin film or dielectric thin film, those with through holes or grooves formed to allow light beams to pass through, and plate-like dielectrics. It refers to a slit plate such as a light-absorbing pattern whose light transmittance is partially different due to diffusion.

  Here, for example, as shown in FIG. 1, the slit plate 2 having a plurality of openings is mounted on the surface from which the light beam of the coherent light source 1 is emitted so that the pitch direction is substantially parallel to the moving direction of the scale 3. To do. As a specific example of mounting the slit plate 2 on the coherent light source 1, it can be easily mounted by forming a plurality of openings directly by patterning or by directly fixing the slit plate 2 to the surface from which the light beam is emitted. be able to.

  Further, by making the pitch direction of the slit plate 2 parallel to the moving direction of the scale 3, the light beam in the moving direction of the scale 3 spreads, and is reflected on the scale 3 by overlapping the point light sources having a plurality of openings in the slit. The light beam forms a diffraction interference pattern on the light receiving element surface of the photodetector.

2. 2. The optical type according to 1, wherein the coherent light source is a mold light source that is molded and mounted on a resin member, and the slit plate is directly formed on a surface that emits a light beam of the mold light source. Displacement sensor.

(Corresponding Embodiment of the Invention)
The sixth embodiment corresponds to the embodiment relating to the present invention.

(Function and effect)
Here, the coherent light source molded and mounted on a resin member is a light source in which a semiconductor chip light source is mounted on a resin substrate on which an electrode pattern is formed, and the periphery thereof is sealed with a resin member. A slit having a plurality of openings 13 and a single opening 15 is directly formed on the surface of the light-emitting side of the coherent light source 1 mounted in a mold, using any one of a metal thin film, a dielectric thin film, and a light-absorbing resin thin film. To do. By using such a coherent light source, it is possible to reduce the number of parts at the time of assembling the optical displacement sensor, and to provide an optical displacement sensor that is easier to assemble and at a lower cost.

3. Of the mold surface of the mold resin member, when the light beam emission surface is the front surface, the opposite side is the rear surface, and the surface substantially perpendicular to the emission direction of the light beam formed to surround the front surface and the rear surface is the side surface, 3. The optical displacement sensor according to 2, wherein a light shielding member is formed on a part or all of the surface and the side surface excluding the slit portion on the surface.

(Corresponding Embodiment of the Invention)
At least the sixth embodiment corresponds to the embodiment relating to the present invention.

(Function and effect)
For example, as shown in FIG. 7, a plurality of first slits are used by using any one of a metal thin film, a dielectric thin film, a light-absorbing resin thin film, and the like on the surface of the light-emitting side of the coherent light source 1 mounted in a mold. The opening 13 and the opening 15 of the second slit are formed directly on the surface of the coherent light source 1 mounted with a mold. At this time, the plurality of first slit openings 13 and the second slit openings 15 may be formed only in the upper planar portion of the mold member from which the light beam is emitted. In order to reduce the adverse effects of light beams emitted from regions other than the plurality of openings 13 of the slits and the openings 15 of the second slits, the light beam emission surface of the mold surface of the resin member is the front surface, the opposite side is the rear surface, When a surface substantially perpendicular to the light beam emitting direction formed so as to surround the front surface and the rear surface is a side surface, the light shielding member 10 is integrated with a part or all of the surface and the side surface except the slit opening of the surface. It is formed.

  Since this light shielding member can significantly reduce the light beam that does not contribute to the diffraction interference pattern formed on the photodetector, it is possible to suppress the DC level of the output signal of the photodetector, and the detection signal Saturation of the signal is suppressed and signal detection with an optimum gain becomes possible.

4). A coherent light source mounted in a mold that emits a light beam;
A scale that is displaced across the light beam emitted from the coherent light source and on which an optical pattern having a first predetermined period and a second optical pattern are formed;
A first photodetector mounted with a light receiving element having photosensitivity in a fixed period in a scale moving direction for detecting a movement of a diffraction interference pattern generated by irradiating the first optical pattern with the light beam; ,
A second photodetector for detecting a beam pattern generated by irradiating the second optical pattern with the light beam;
An optical displacement sensor comprising:
A first slit having a plurality of openings in a moving direction of the scale, and forming a light beam to be applied to the first optical pattern on a mold surface on a side from which the light beam of the coherent light source is emitted; An optical displacement sensor, comprising: a second slit for forming a light beam irradiated on the second optical pattern.

(Corresponding Embodiment of the Invention)
At least the sixth, seventh, eighth, ninth, and tenth embodiments correspond to the embodiments relating to the present invention.

(Function and effect)
For example, as shown in FIGS. 6A and 6B, a cycle in which the light beam of the coherent light source 1 mounted on the mold is irradiated with the light beam on the first periodic pattern 6 on the scale 3. A plurality of first openings 13 of the first slit and an opening 15 of the second slit are formed. The pitch direction of the plurality of openings 13 of the periodic first slit is arranged substantially parallel to the pitch direction of the optical pattern 6 having a predetermined period on the scale 3.

  A part of the light beam emitted from the coherent light source 1 is irradiated to the periodic pattern 6 formed on the scale 3 through the plurality of openings 13 of the first slit, and reflected and diffracted by the periodic pattern 6. Then, a light / dark pattern is formed on the first photodetector 4. Thereby, the movement of the scale 3 can be detected. Similarly, another part of the light beam emitted from the coherent light source 1 passes through the opening 15 of the second slit and is irradiated to the reference position pattern 7 formed on the scale 3. The light beam reflected by is incident on the second photodetector 5. As a result, the reference position of the scale 3 can be detected.

  The plurality of periodic first apertures 13 and second slit apertures 15 are fixed or directly formed on the surface from which the light beam of the coherent light source 1 mounted by mold is emitted, so that mounting is easy. is there. Since the pitch direction of the plurality of openings 13 of the periodic first slit is arranged substantially parallel to the pitch direction of the optical pattern 6 having a predetermined period on the scale 3, the light beam on the scale 3 has a pitch of the scale 3. A wide range of displacement information can be reflected in the diffraction interference pattern, and a sensor that is resistant to dust and scratches on the scale 3 can be realized.

5. The distance between the surface of the first slit on which the optical pattern is formed and the surface of the scale on which the first optical pattern is formed is z1,
The distance between the surface of the scale on which the first optical pattern is formed and the surface on which the light receiving element of the first photodetector is formed is z2,
The period of the scale movement direction of the optical pattern of the first predetermined period formed on the scale is p1,
Assuming that the pitch of the plurality of openings formed in the first slit in the scale moving direction is pst, pst is approximately p1 × (z1 + z2) / z2.
5. The optical displacement sensor according to 4, wherein the optical displacement sensor is represented by:

(Function and effect)
The distance between the surface on which the plurality of periodic openings 13 are formed as the first slit and the surface on which the first optical pattern of the scale 3 is formed is z1, and the first optical pattern 6 of the scale 3 is formed. Z2 is the distance between the first surface and the light receiving element forming surface of the first photodetector 4, and p1 is the period in the scale movement direction of the first predetermined period optical pattern formed on the scale 3.
When the wavelength of the coherent light source 1 is λ and the natural number is n, in order to transfer the light / dark pattern on the scale 3 to the surface of the first photodetector 4,
(1 / z1) + (1 / z2) = λ / (n × (p1) ² )
It is necessary to satisfy the following conditions. If the period of the diffraction interference pattern imaged on the light receiving surface of the first photodetector 4 at this time is p2,
p2 = p1 × (z1 + z2) / z1
It becomes.

If the pitch of openings in the moving direction of the scale 3 in the plurality of openings 13 of the first slit is pst, the relationship between the pitch pst of the plurality of openings of the slit and the diffraction interference pattern pitch p2 on the first photodetector 4 is expressed as follows. pst: p2 = z1: z2
Need to be formed.

As a result, the light beam emitted from the plurality of openings 13 of the first slit is irradiated on the first optical pattern on the scale 3, and the diffraction interference pattern is transferred onto the first photodetector 4. Is,
pst = p1 × (z1 + z2) / z2
It becomes.

  When the opening pitch of the plurality of openings 13 of the first slit substantially satisfies the above condition in the moving direction of the scale, the diffraction interference pattern on the scale 3 using the Talbot principle is projected onto the first photodetector 4. be able to.

6). The plurality of openings of the first slit and the opening of the second slit are in the direction in which the scale moves in a plane where the plurality of openings of the first slit and the opening of the second slit are formed. 5. The optical displacement sensor according to 4, wherein the optical displacement sensor is formed by shifting a predetermined distance in a substantially perpendicular direction.

(Corresponding Embodiment of the Invention)
At least fifth, sixth, seventh, eighth, ninth, and sixteenth embodiments correspond to the embodiments of the present invention.

(Function and effect)
A part of the light beam emitted from the coherent light source 1 is irradiated to the periodic pattern 6 formed on the scale 3 through the plurality of openings 13 of the first slit, and reflected and diffracted by the periodic pattern 6. Then, a diffraction interference pattern is formed on the first photodetector 4. Thereby, the movement of the scale 3 can be detected. Similarly, another part of the light beam emitted from the coherent light source 1 passes through the opening 15 of the second slit and is irradiated to the reference position pattern 7 formed on the scale 3. The light beam reflected by is incident on the second photodetector 5. As a result, the reference position of the scale 3 can be detected.

In this way, the light beams emitted from the plurality of openings 13 of the first slits and the opening 15 of the second slits are irradiated to the periodic pattern 6 and the reference position pattern 7 on the scale, thereby suppressing the respective interactions. In order to do this, at least the plurality of openings 13 of the first slit and the openings 15 of the second slit are substantially in the plane in which the plurality of openings 13 of the first slit are formed with respect to the moving direction of the scale 3. It is necessary that the predetermined distance is shifted in the vertical direction.

  With this configuration, the first optical pattern and the second reference position detection pattern which are different from each other on the scale 3 are irradiated with the light beams emitted from the plurality of openings 13 of the first slits and the opening 15 of the second slits. Thus, the displacement signal and the reference position signal whose interaction is suppressed by the corresponding first photodetector 4 and second photodetector 5 can be obtained.

7). The plurality of openings of the first slit and the opening of the second slit are arranged in a direction in which the scale moves in a plane where the plurality of openings of the first slit and the opening of the second slit are formed. 7. The optical displacement sensor according to 6, wherein the optical displacement sensor is formed so as to overlap at least partially after being shifted by a predetermined distance in a direction substantially perpendicular to the surface.

(Corresponding Embodiment of the Invention)
The embodiment relating to the present invention corresponds to at least the sixteenth embodiment.

(Function and effect)
Since the opening portion of the second slit opening 15 overlaps a part of the formation region of the plurality of first opening 13 of the first slit, the light beam that has passed through the second slit opening 15 is on the scale. The second reference position detection pattern is irradiated. The light beam reflected by the second reference position detection pattern enters the second photodetector 5 and the reference position is detected. At the same time, a part of the light beam that has passed through the opening 15 of the second slit is also applied to the first periodic pattern 6 on the scale. By detecting a part of the light beam reflected by the first periodic pattern on the scale by the first photodetector, the movement amount detection signal and the reference position detection signal can be synchronized.

  In addition, since the light beam that has passed through the plurality of openings 13 of the first slit has a wide beam spread with respect to the scale movement direction, a signal corresponding to the reference position detection pattern on the scale can be obtained also by the second photodetector. . On the other hand, the light beam that has passed through the aperture 15 of the single slit second slit used for the detection of the reference position is irradiated onto the second reference position detection pattern on the scale, reflected, and reflected to the second position. The pattern generated on the photodetector is detected by the second photodetector.

  By utilizing the fact that the reference position signal level detected at this time increases sharply, the opening area of the slit is extended to the opening portion of the first slit, so that the reference position on the scale for detecting the reference position is obtained. The amount of light to the detection pattern is secured, the signal level is increased, and the reference position can be reliably detected.

8. A coherent light source that emits a light beam; a scale that is displaced across the light beam emitted from the coherent light source and formed with an optical pattern having a predetermined period; and A photodetector having a light receiving element having photosensitivity in a constant period in a scale moving direction for detecting the movement of the diffraction interference pattern generated by being irradiated with the light beam, and the light beam emitted from the coherent light source is An optical displacement sensor comprising a slit plate disposed on an optical path toward the scale and having a plurality of openings formed in the moving direction of the scale,
The slit plate is fixed to the same plane as the formation surface of the light receiving element so that the upper surface or the lower surface of the portion where the plurality of openings are formed and the light receiving surface of the light receiving element are in the same plane. An optical displacement sensor characterized.

(Corresponding Embodiment of the Invention)
The embodiment relating to the present invention corresponds to at least the second and third embodiments.

(Function and effect)
For convenience of description, it is assumed that the sensor substrate 100 is perpendicular to the sensor substrate 100 and the slit direction is “upward”. The embodiment will be described with reference to FIGS. A slit plate 2 having a plurality of openings formed in the moving direction of the scale 3 disposed above the coherent light source 1 is further provided, and the slit plate 2 is arranged on either surface thereof in the moving direction of the scale of the photodetector. The slit plate is flush with the formation surface of the light receiving element having photosensitivity at a constant period in the scale movement direction of the photodetector 4 so that the light receiving surface of the light receiving element having photosensitivity at a constant period is in the same plane. It is fixed to. With this configuration, the distance z1 between the surface of the slit on which the optical pattern is formed and the surface of the scale on which the optical pattern is formed, the surface of the scale on which the optical pattern is formed, and the photodetector The distance z2 from the effective light receiving surface automatically matches (that is, z1 = z2 is maintained in any case).

  As a result, as shown by the equations (2) and (3), the diffraction interference pattern on the light receiving surface is twice the optical pattern period on the scale (2p1) regardless of the distance between the scale and the sensor head. Fixed to. The opening pitch pst to be formed in the slit plate is also fixed to twice the optical pattern period p1 on the scale.

  Therefore, even if the distance between the scale and the sensor head changes, it is not necessary to change the pitch p2 or the slit opening pitch pst of the light receiving elements having photosensitivity with a constant period in the scale moving direction.

  Furthermore, since the relationship of z1 = z2 is preserved during design and manufacturing, the slit opening pitch pst can be set without depending on the mounting tolerance of the gap between the scale and the sensor head.

  A high-resolution displacement sensor can be obtained by detecting the diffraction interference pattern on the photodetector 4 as an intensity signal at a predetermined phase interval and subjecting the detected intensity signal to phase division processing.

9. The distance between the surface on which the plurality of openings of the slit is formed and the surface on which the optical pattern of the previous scale is formed is z1, the surface on which the optical pattern of the scale is formed, and the scale moving direction of the photodetector Z2 is the distance from the formation surface of the light receiving element having photosensitivity at a constant period
The period of the optical pattern in the scale moving direction in the scale is p1,
If the pitch of the plurality of openings in the slit movement direction in the slit is pst,
pst is approximately p1 × (z1 + z2) / z2.
The optical displacement sensor according to any one of 1, 2, 3, and 8, characterized by:

(Corresponding Embodiment of the Invention)
The embodiment relating to the present invention corresponds to at least the first to fourth embodiments.

(Function and effect)
The wavelength λ of the light source, the pitch pst of the slit, the pitch p1 of the scale, the distance from the slit to the scale z1, and the distance from the scale to the formation surface of the light receiving element having photosensitivity in a fixed period in the scale moving direction of the photodetector. When z2 is satisfied, when the following equation is satisfied, a period p2 similar to the periodic pattern formed on the scale is formed on the formation surface of the light receiving element having photosensitivity at a constant period in the scale moving direction of the photodetector. A diffraction interference pattern is formed.

(1 / z1) + (1 / z2) = λ / (n (p1) ² ) (1)
p2 = p1 × (z1 + z2) / z1 (2)
pst = p1 × (z1 + z2) / z2 (3)
Here, n is a natural number.

  Therefore, a light receiving element having photosensitivity with a constant period in the direction of scale movement on the photodetector is arranged at a period p2 expressed by equation (2), and a plurality of slit pitches of slits are set to pst expressed by equation (3). By doing so, it becomes possible to detect the movement of the diffraction interference pattern. That is, when the light source, the scale, and the light receiving element having photosensitivity at a constant period in the scale moving direction are in the arrangement shown by the formula (2), the plurality of slit pitches are set as pst shown by the formula (3). Thus, a diffraction interference pattern is formed on the light receiving element having photosensitivity at a constant period in the scale moving direction. Furthermore, in this case, by setting the pitch in the scale movement direction of the light receiving element having photosensitivity at a constant cycle in the scale movement direction to p2 expressed by the equation (2), the photosensitivity is obtained at a constant cycle in the scale movement direction. Since the diffraction interference pattern formed on the light receiving surface of the light receiving element matches the light receiving element pitch, it is possible to detect the light intensity for each specific phase of the diffraction interference pattern with a constant period in the scale movement direction. The movement of the diffraction interference pattern accompanying the movement of the scale can be detected.

10. The optical displacement sensor according to any one of 1, 4, 5, 6, 7, and 8, wherein the light source side surface of the slit is subjected to antireflection treatment.

(Corresponding Embodiment of the Invention)
Embodiments relating to the present invention correspond to Embodiments 1 to 17 except for the sixth embodiment.

(Function and effect)
The antireflection treatment refers to applying a low reflection film coating or making the surface of the slit plate 2 irregularly reflected. Reflected light from the surface of the slit opening on the light source side of the slit plate 2 returns to the coherent light source 1, the light output of the coherent light source 1 fluctuates, and as a result, the displacement signal level of the photodetector 4 fluctuates, and the amount of displacement In order to suppress the occurrence of errors, at least the surface of the slit opening of the slit plate 2 is subjected to antireflection treatment. As a result, the return light is reduced, the light output of the coherent light source 1 can be stabilized, and the displacement amount of the scale 3 can be detected correctly.

11. The coherent light source has a lens for controlling the spread of a light beam at a light beam emitting portion, and a flat surface capable of fixing a slit plate in parallel to the scale surface. , 4 to 10. The optical displacement sensor according to any one of 4 to 10.

(Corresponding Embodiment of the Invention)
At least the third, fourth, fifth, seventh, eighth, and ninth embodiments correspond to the embodiments of the present invention.

(Function and effect)
Since the optical element is formed by the mold and the surface on the light emitting side is integrally formed flat, the shape of the light beam emitted from the surface on the light emitting side is controlled. Further, since the fixing surface of the slit is flat, the level of the slit surface during fixing can be easily obtained.

For example, by controlling the spread of the light beam by the optical element a in FIGS. 9A and 9B, the light beam that has passed through the plurality of openings 13 of the first slit of the slit plate 2 is periodically cycled on the scale. One optical pattern is efficiently irradiated. Further, when the slit plate 2 is composed of a plurality of periodic first apertures 13 and a single second aperture 15, the optical element a controls the spread of the light beam. The light beams emitted from the plurality of openings 13 of the first slit and the openings of the second slit are respectively irradiated and reflected on the corresponding first periodic optical pattern and second reference position detection pattern on the scale, Since the corresponding periodic optical pattern and reference position pattern on the first photodetector and the second photodetector are transferred, the position displacement signal and the reference position detection signal with reduced mutual interference can be detected.

12 12. The optical displacement sensor according to 11, wherein the lens is formed below the flat surface when the slit plate is disposed above the coherent light source.

(Corresponding Embodiment of the Invention)
The embodiment relating to the present invention corresponds to at least the third and ninth embodiments.

(Function and effect)
When the slit plate is disposed above the coherent light source, since the lens is formed below the flat surface, it is easy to mount the slit plate, and between the lens and the slit plate. By providing a space, the light collecting effect of the lens can be expected. Further, by designing the mold shape, a mold light source in which a large number of lens-like components are integrally mounted on a chip can be easily manufactured, and the light beam divergence angle can be controlled.

13. 12. The optical displacement sensor according to 11, wherein the lens is a planar optical element such as a Fresnel lens.

(Corresponding Embodiment of the Invention)
At least the third, fifth, eighth, and ninth embodiments correspond to the embodiments of the present invention.

(Function and effect)
A Fresnel lens or a condensing grating for condensing the light beam is mounted on the light beam exit surface of the mold light source, and a slit plate is mounted on the surface. Since this Fresnel lens or condensing grating can be manufactured by semiconductor manufacturing technology, it can be produced in large quantities at a low price, and a module light source with controlled light beam spread can be obtained at a low price.

It is a figure which shows schematic structure of the optical displacement sensor as an optical displacement sensor which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of an optical displacement sensor. It is sectional drawing of the center part of the optical displacement sensor shown in FIG. It is a schematic block diagram of the optical displacement sensor which concerns on 3rd Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 4th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 5th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 6th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 7th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 8th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 9th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 10th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 11th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 12th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 13th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 14th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 16th Embodiment of this invention. It is a schematic block diagram of the optical displacement sensor which concerns on 17th Embodiment of this invention. It is a figure which shows the structure of the conventional optical displacement sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Coherent light source, 2 ... Slit plate, 3 ... Scale, 4-1 ... Light receiving element, 4 ... Photodetector, 6 ... Optical pattern, 13 ... Multiple openings, 100 ... Sensor substrate, 200 ... Sensor head.

Claims (13)

A coherent light source that emits a light beam;
A scale that is displaced across the light beam emitted from the coherent light source and on which an optical pattern having a predetermined period is formed;
A photodetector equipped with a light receiving element having photosensitivity at a constant period in a scale moving direction for detecting the movement of the diffraction interference pattern generated by irradiating the optical pattern with the light beam with the predetermined period;
An optical displacement sensor comprising:
An optical displacement sensor characterized in that a slit plate having a plurality of openings in the moving direction of the scale is provided on a surface from which the light beam of the coherent light source is emitted. 2. The optical device according to claim 1, wherein the coherent light source is a mold light source molded and mounted on a resin member, and the slit plate is directly formed on a surface of the mold light source that emits a light beam. Displacement sensor. When the light beam emitting surface of the mold surface of the mold resin member is the front surface, the opposite side is the rear surface, and the surface substantially perpendicular to the light beam emitting direction formed so as to surround the front surface and the rear surface is the side surface, 3. The optical displacement sensor according to claim 2, wherein a light shielding member is formed on a part of or all of the surface and the side surface excluding the slit portion on the surface. A coherent light source mounted with a mold that emits a light beam;
A scale that is displaced across the light beam emitted from the coherent light source and on which an optical pattern having a first predetermined period and a second optical pattern are formed;
A first photodetector mounted with a light receiving element having photosensitivity in a fixed period in a scale moving direction for detecting a movement of a diffraction interference pattern generated by irradiating the first optical pattern with the light beam; ,
A second photodetector for detecting a light beam pattern generated by irradiating the second optical pattern with the light beam;
An optical displacement sensor comprising:
A first slit having a plurality of openings in a moving direction of the scale, and forming a light beam to be applied to the first optical pattern on a mold surface on a side from which the light beam of the coherent light source is emitted; An optical displacement sensor, comprising: a second slit for forming a light beam irradiated on the second optical pattern. The distance between the surface of the first slit where the plurality of openings are formed and the surface of the scale where the first optical pattern is formed is z1,
The distance between the surface of the scale on which the first optical pattern is formed and the surface on which the light receiving element of the first photodetector is formed is z2,
The period of the scale movement direction of the optical pattern of the first predetermined period formed on the scale is p1,
Assuming that the pitch of the plurality of openings formed in the first slit in the scale moving direction is pst, pst is approximately p1 × (z1 + z2) / z2.
The optical displacement sensor according to claim 4, wherein the optical displacement sensor is represented by: The plurality of openings of the first slit and the opening of the second slit are a moving direction of the scale in a plane in which the plurality of openings of the first slit and the opening of the second slit are formed. 5. The optical displacement sensor according to claim 4, wherein the optical displacement sensor is formed by shifting a predetermined distance in a direction substantially perpendicular to the direction. The plurality of openings of the first slit and the opening of the second slit are a moving direction of the scale in a plane in which the plurality of openings of the first slit and the opening of the second slit are formed. 7. The optical displacement sensor according to claim 6, wherein the optical displacement sensor is formed so as to overlap at least partly after being shifted by a predetermined distance in a direction substantially perpendicular to. A coherent light source that emits a light beam;
A scale that is displaced across the light beam emitted from the coherent light source and on which an optical pattern having a predetermined period is formed;
A photodetector equipped with a light receiving element having photosensitivity at a constant period in a scale moving direction for detecting the movement of the diffraction interference pattern generated by irradiating the optical pattern with the light beam with the predetermined period;
A slit plate in which a light beam emitted from the coherent light source is disposed on an optical path toward the scale, and a plurality of openings are formed in the moving direction of the scale;
An optical displacement sensor comprising:
The slit plate is fixed to the same plane as the formation surface of the light receiving element so that the upper surface or the lower surface of the portion where the plurality of openings are formed and the light receiving surface of the light receiving element are in the same plane. An optical displacement sensor characterized. The distance between the surface on which the plurality of openings of the slit are formed and the surface on which the optical pattern of the scale is formed is z1,
Z2 represents the distance between the surface on which the optical pattern of the scale is formed and the formation surface of the light receiving element having photosensitivity at a constant period in the scale moving direction of the photodetector.
The period of the optical pattern in the scale moving direction in the scale is p1,
If the pitch of the plurality of openings in the slit movement direction in the slit is pst,
pst is approximately p1 × (z1 + z2) / z2.
9. The optical displacement sensor according to claim 1, wherein the optical displacement sensor is represented by the following formula. The optical displacement sensor according to any one of claims 1, 4, 5, 6, 7, 8, and 9, wherein the light source side surface of the slit plate is subjected to antireflection treatment. . The coherent light source has a lens for controlling the spread of a light beam at a light beam emitting portion, and a flat surface capable of fixing a slit plate in parallel to the scale surface. Item 11. The optical displacement sensor according to any one of Items 1, 4 to 10. 12. The optical displacement sensor according to claim 11, wherein the lens is formed below the flat surface when the slit plate is disposed above the coherent light source. The optical displacement sensor according to claim 11, wherein the lens is a planar optical element such as a Fresnel lens.

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