JP5147877B2 - Optical encoder sensor and optical encoder - Google Patents

Description

  The present invention relates to an optical encoder sensor for optically detecting a pattern on an optical scale, and an optical encoder including the optical encoder sensor.

  In general, a transmissive encoder and a reflective encoder are known as optical encoders. The transmissive encoder is arranged so that a light emitting element that emits light and a light receiving element that receives light is sandwiched between the optical scale and a light receiving element that has passed through the optical scale. It is configured to receive light. The reflective encoder has a light emitting element and a light receiving element arranged on one side of the optical scale, and is configured to receive reflected light emitted from the light emitting element and reflected by the optical scale by the light receiving element.

  As described above, the reflective encoder has the light emitting element and the light receiving element arranged on the same side with respect to the optical scale, and thus can contribute to a reduction in the sensor head size. In addition, a reflection type encoder using an LD (laser diode) such as a surface emitting laser as a light emitting element is known. However, for example, when detecting a plurality of optical patterns formed on an optical scale, the LD has higher directivity than an LED (light emitting diode), so a plurality of light emitting elements are required for each optical pattern. This increases the cost. Furthermore, since the area of light projected on each optical pattern is also narrow, resistance to foreign matters and the like is reduced. In general, an LD has a shorter lifetime than an LED and a narrow operating temperature range. Therefore, although it is desirable to use LED for a light emitting element, since LED is a diffused light source, there exists a fault that light utilization efficiency is low and sufficient light quantity cannot be obtained.

  On the other hand, examples of reflective optical encoders configured to use LEDs as light emitting elements to improve light utilization efficiency include those disclosed in Patent Document 1, Patent Document 2, and Patent Document 3. It is done.

  In Patent Document 1, an LED chip is disposed at a focal position of a first reflecting member constituted by a spherical surface or an aspherical surface, a light beam diffused and emitted from the LED is collimated by the first reflecting member, and second A configuration is disclosed in which light is incident on a scale at a 45-degree angle by a reflecting member, and light reflected from the scale is detected by a light receiving element. With such a configuration, the amount of movement of the scale can be detected.

  In Patent Document 2, a light source, a first grating, a scale corresponding to the second grating, and a light receiving element formed in an array are provided, and a condensing lens is provided immediately after the light source. A configuration in which the emitted light beam is efficiently guided to the first grating and the scale is disclosed. With such a configuration, the amount of movement of the scale can be detected by detecting the reflected light from the scale with the arrayed light receiving element.

  In patent document 3, it has a structure which has a light source, each 1st and 2nd scale, and a light receiving element, arrange | positions the diffraction grating fixed just before the light receiving element, It is disclosed that the relative movement is detected by the amount of light received by the light receiving element. According to such a configuration, even when the gap between the first scale and the second scale is changed by inserting the imaging lens between the diffraction grating and the scale, the gap is It is within the depth of field. Therefore, the structure is strong against displacement. In addition, since the light beam from the light source can be deflected by forming the slope on the first scale immediately after the light source, the vicinity of the optical axis having a high light intensity can be used effectively.

JP 2003-106871 A JP 2005-49345 A JP 2005-106604 A

  However, the optical encoder of Patent Document 1 has the following problems. That is, the use efficiency of the light beam emitted from the LED can be improved by using a reflection member constituted by a spherical surface or an aspheric surface. However, since two reflection members are used, the reflectance of the reflection member is increased. As a result, there is a problem that the amount of light decreases. In addition, the two reflection members, the light source, and the light receiving element are independently arranged, and there is a problem that the influence on the detection accuracy due to the positional deviation of each optical component becomes large. Moreover, there is also a problem that the cost is increased by using two reflecting members.

  The optical encoder of Patent Document 2 has the following problems. That is, since the condensing lens is inserted immediately after the light source, the utilization efficiency of the light emitted from the light source can be improved. However, the lens, the first grating, and the arrayed light receiving element are all attached separately. Therefore, there is a problem that the influence on the detection accuracy due to the positional deviation of each optical component becomes large. Further, the substrate surface on which the light source is attached and the scale are parallel to each other, and the light beam irradiated on the optical pattern of the scale uses a light beam having an angle inclined from the optical axis of the light source. Therefore, there is a problem that a light beam near the center of the optical axis with high intensity is not used.

  Further, the optical encoder of Patent Document 3 has the following problems. That is, since the slope for deflecting the light beam, the imaging lens, and the diffraction grating are integrated, it is easy to assemble, but when using an LED, only a part of the light beam is irradiated onto the scale. There is a problem that the light utilization efficiency is low.

  The present invention has been made to solve the above-described problems, and provides an optical encoder sensor and an optical encoder that are capable of high-precision detection and have high light utilization efficiency as compared with the prior art. Objective.

In order to achieve the above object, the present invention is configured as follows.
That is, an optical encoder sensor in one embodiment of the present invention includes a light-emitting element, a first diffraction grating through which light emitted from the light-emitting element passes and generates a periodic light amount distribution from the light, and the first diffraction A second diffraction grating through which reflected light of a specific frequency reflected by an optical scale among light passing through the grating is transmitted; a light receiving element that receives light that has passed through the second diffraction grating; and the light emitting element, A sensor unit that integrally forms the light receiving element, the first diffraction grating, and the second diffraction grating, and the sensor unit is disposed between an optical path between the light emitting element and the first diffraction grating. A light deflection element for deflecting light emitted from the light emitting element is integrally provided, and the light deflection element has a diffusion portion for diffusing the light emitted from the light emitting element .

The optical encoder sensor may be configured as follows.
That is, a light emitting element for emitting light, a first diffraction grating for generating a periodic light quantity distribution of light from the light emitting element, and a specific frequency among the lights from the first diffraction grating In an optical encoder comprising an optical scale for taking out light, a second diffraction grating for transmitting light from the optical scale, and a light receiving element for receiving light from the second diffraction grating An optical deflection element is provided between the light emitting element and the first diffraction grating, and among the light rays from the light emitting element, the light rays near the optical axis are bent in a direction to diverge with respect to the optical axis. A diffusion part and a condensing part for bending light rays inward from the optical axis are formed for the peripheral light far from the optical axis, and the light deflection element is an index in which a first diffraction grating and a second diffraction grating are formed. It is molded integrally on the board And butterflies.

  According to the optical encoder sensor in one aspect of the present invention, since the light deflection element is provided, the light rays near the optical axis out of the light emitted from the light emitting elements are diverged with respect to the optical axis. The peripheral light that is bent and far from the optical axis is bent inward with respect to the optical axis. Therefore, it is possible to use both the light beam near the strong optical axis and the light beam having a large divergence angle with respect to the optical axis, so that the light use efficiency can be improved as compared with the conventional case. Furthermore, since the light emitting element, the light receiving element, the first diffraction grating, the second diffraction grating, and the light deflecting element are integrally formed as a sensor unit, the influence on the detection accuracy such as positional deviation compared to the conventional case. Can be reduced. As described above, the optical encoder sensor according to one embodiment of the present invention can increase the detection accuracy of the optical scale and improve the light utilization efficiency as compared with the conventional sensor.

  In addition, the optical encoder sensor according to one embodiment of the present invention is a reflective type and is thinned. However, as described above, the light-emitting element, the light-receiving element, the first diffraction grating, the second diffraction grating, and Since the optical deflection element is integrally formed as a sensor unit, the thickness is further reduced. In addition, the light deflection element does not require alignment between the first diffraction grating and the second diffraction grating, and the assembly becomes easy.

It is a figure which shows the structure of the optical encoder in Embodiment 1 of this invention. FIG. 2 is an enlarged view of an optical deflection element provided in the optical encoder sensor that constitutes the optical encoder shown in FIG. 1. It is a perspective view which shows the modification of the optical deflection | deviation element shown in FIG. It is sectional drawing which shows another modification of the optical deflection | deviation element shown in FIG. It is sectional drawing which shows the other modification of the optical deflection | deviation element shown in FIG. It is a top view of the package with which the sensor for optical encoders shown in FIG. 1 is equipped. It is a top view of the index board | substrate with which the sensor for optical encoders shown in FIG. 1 is equipped. It is a perspective view of the optical scale with which the optical encoder shown in FIG. 1 is equipped. It is a perspective view which shows the modification of the optical scale shown in FIG. It is a perspective view which shows another modification of the optical scale shown in FIG. It is a figure which shows the structure of the optical encoder in Embodiment 2 of this invention. It is an enlarged view of the optical deflection | deviation element with which the sensor for optical encoders which comprises the optical encoder shown in FIG. It is sectional drawing which shows the modification of the optical deflection | deviation element shown in FIG. It is sectional drawing which shows another modification of the optical deflection | deviation element shown in FIG. It is a figure which shows the structure of the optical encoder in Embodiment 3 of this invention. It is an enlarged view of the optical deflection | deviation element with which the sensor for optical encoders which comprises the optical encoder shown in FIG. 14 is equipped. It is a figure which shows the structure of the optical encoder in Embodiment 4 of this invention. FIG. 17 is an enlarged view of an optical deflection element provided in the optical encoder sensor that constitutes the optical encoder shown in FIG. 16. It is sectional drawing which shows the modification of the optical deflection | deviation element shown in FIG. It is an enlarged view of the optical deflection | deviation element with which the sensor for optical encoders which comprises the optical encoder in Embodiment 5 of this invention is equipped. It is a figure which shows the structure of the optical encoder in Embodiment 6 of this invention. It is a figure which shows the structure in the modification of the optical encoder shown in FIG.

  An optical encoder sensor according to an embodiment of the present invention and an optical encoder provided with the optical encoder sensor will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.

Embodiment 1 FIG.
FIG. 1 shows the configuration of the optical encoder 101 according to the first embodiment. The optical encoder 101 includes an optical encoder sensor 10A, an optical scale 30, and a movement amount detection unit 70 as basic components. Hereinafter, these components will be sequentially described.

  The optical encoder sensor 10 </ b> A includes a light emitting element 1, a light receiving element 2, a first diffraction grating 3, a second diffraction grating 4, and a light deflection element 5, and further, the light emitting element 1, the light receiving element 2, and the first light emitting element 1. A sensor unit 6 that integrally forms the diffraction grating 3, the second diffraction grating 4, and the light deflection element 5 is provided. The sensor unit 6 is a combination of a package 6 a on which the light emitting element 1 and the light receiving element 2 are mounted and an index substrate 6 b on which the first diffraction grating 3, the second diffraction grating 4, and the light deflection element 5 are formed.

  The package 6a is a non-translucent member having a concave cross section in the present embodiment, and one light emitting element 1 is arranged at the center of the bottom surface 6a-2 of the recess 6a-1 as shown in FIG. 6A. The two light receiving elements 2 are arranged on both sides of the light emitting element 1 on the bottom surface 6a-2. In the present embodiment, the number of the light emitting elements 1 is one. However, it is possible to arrange two or more sets in parallel, with the light emitting element 1, the light receiving element 2, and the two types of optical patterns 31 (FIG. 7) as one set. is there. In this case, higher resolution can be achieved by changing the optical pattern to a different pitch from a long cycle pitch to a short cycle pitch.

The light emitting element 1 is a light source for projecting light onto an optical scale 30 through a first diffraction grating 3 to be described later. For example, an LED or the like can be used. As described above, the LED is more preferable.
The light receiving element 2 is a light detecting means for detecting light reflected by the optical scale 30 and passed through a second diffraction grating 4 described later. For example, a light receiving element such as a PD (photodiode) is employed. The

The index substrate 6b is, for example, a plate-like member formed of a transparent resin such as polycarbonate, and has the same planar shape as the package 6a, as shown in FIG. 6B, and forms legs 6a-1 of the package 6a. It is a member that is fixed to the portion 6a-3 and closes the recess 6a-1. The material of the index substrate 6b is not particularly limited as long as it is a transparent resin.
On the inner surface 6b-1 of the index substrate 6b located on the recess 6a-1 side, a light deflection element 5 described below is integrally formed with the index substrate 6b at a position corresponding to the light emitting element 1. A first diffraction grating 3 and a second diffraction grating 4 described below are formed on the outer surface 6b-2 of the index substrate 6b facing the inner surface 6b-1.

  The light deflecting element 5 is a means for deflecting the light emitted from the light emitting element 1, and in the present embodiment, as shown in FIG. 2, the light deflecting element 5 side of the flat inner surface 6b-1 of the index substrate 6b. In this embodiment, it is formed in a circular planar shape as shown in FIG. 6B. Therefore, in this embodiment, the light deflection element 5 is formed in a substantially semispherical shape on the inner surface 6b-1 of the index substrate 6b. Such an optical deflection element 5 includes a condensing part 5a made of a convex lens-like spherical surface or a part of an aspherical surface, and a flat flat part 5b formed on the convex top part. The center position of the flat portion 5 b corresponds to the position of the optical axis 1 a in the light emitting element 1.

  In such an optical deflection element 5, among the outgoing rays of the light emitting element 1, the rays incident on the flat portion 5 b pass through the optical deflection element 5 as they are without changing the direction of the rays and irradiate the first diffraction grating 3. Is done. On the other hand, among the light rays emitted from the light emitting element 1, the light rays that have entered the light condensing unit 5a are irradiated on the first diffraction grating 3 by changing the direction of the light rays to the inner side (on the optical axis 1a side) with respect to the optical axis 1a. The

In the present embodiment, the light deflection element 5 has a substantially semispherical shape having the condensing part 5a and the flat part 5b as described above. However, the light deflecting element 5 has, for example, an oval planar shape and is parallel to the paper surface of FIG. 6B, the light collecting portion 5a and the flat portion 5b are formed in the direction of the arrow 30a shown in FIG. 6B. On the other hand, at both ends in the direction perpendicular to the plane of FIG. 2, that is, the direction of the arrow 30b shown in FIG. The shape which formed only the condensing part 5a may be sufficient. The direction of the arrow 30b is an arrangement direction of a first diffraction grating 3 and a second diffraction grating 4 which are shown in FIG. 6B and will be described later (henceforth referred to as “an arrangement direction 30b” hereinafter). Also, as shown in FIG. 6B, a direction perpendicular to the arrangement direction 30b is indicated by an arrow 30a. Further, as shown in FIG. 3, a cylindrical shape may be used in which the condensing part 5a and the flat part 5b are formed in the direction of the arrow 30a, and the end face in the arrangement direction 30b is a flat face 5c. By adopting a cylindrical shape, light can be condensed only in one direction.
Further, the condensing unit 5a may be a spherical surface or an aspherical surface different in the moving direction of the optical scale 30 (the arrangement direction 30b) and the orthogonal direction orthogonal to the moving direction (the direction of the arrow 30a). good.

Furthermore, as in the optical deflection element 5A shown in FIG. 4, the light condensing part 5a may be a simple inclined surface 5d instead of a spherical surface or an aspherical surface. Further, like the light deflection element 5B shown in FIG. 5, the inner surface 6b-1 of the index substrate 6b may be concave. In the form shown in FIG. 5, the light deflection element 5B is formed of a flat portion 5b and a slope 5d. The planar shape of the light deflection elements 5A and 5B can be the above-described circle, oval, cylindrical shape, or the like.
The light deflection elements 5A and 5B having the inclined surfaces 5d as shown in FIGS. 4 and 5 are easier to manufacture than when the condensing portion 5a is spherical or aspherical. Further, the index substrate 6b can be thinned.
Further, the inclined surface 5d of the light deflection element 5B shown in FIG. 5 may be formed from a concave lens-shaped spherical surface or a part of an aspherical surface.

Next, the first diffraction grating 3 and the second diffraction grating 4 will be described.
On the outer surface 6b-2 of the index substrate 6b, the first diffraction grating 3 is formed at a position to which the light emitted from the light emitting element 1 that has passed through the light deflecting element 5 is irradiated. The second diffraction grating 4 is an optical element that is formed at a position where the reflected light reflected by the optical scale 30 is irradiated and transmits the reflected light. As shown in FIG. 6B, the first diffraction grating 3 and the second diffraction grating 4 are formed in a square shape, and are composed of a light transmitting portion and a light shielding portion. Specifically, the light shielding part may be formed by patterning with a metal by lithography, or the light transmitting part and the light shielding part may be formed by a V-protrusion shape or a V-groove shape as in the optical scale 30 described later. May be formed.

  As described above and as shown in FIG. 6B, the index substrate 6b is formed by integrally forming the first diffraction grating 3, the second diffraction grating 4, and the light deflection element 5. Therefore, the optical encoder sensor 10A can be reduced in thickness, and the alignment of the optical deflection element 5 with the first diffraction grating and the second diffraction grating becomes unnecessary, and the detection accuracy is improved as compared with the conventional one. It can be designed and can be easily assembled.

  The first diffraction grating and the second diffraction grating are not particularly limited in shape and manufacturing method as long as the light transmission part and the light shielding part are formed. Further, if an antireflection film is applied to the index substrate 6b, the S / N ratio can be further improved.

Further, as shown in FIG. 6A, the package 6a has, on the bottom surface 6a-2, a package side alignment pattern 7a that serves as a reference when the light emitting element 1 and the light receiving element 2 are mounted on the bottom surface 6a-2 of the recess 6a-1. It is preferable to have. Further, as shown in FIG. 6B, the index substrate 6b has an index side alignment pattern 7b serving as a reference when the first diffraction grating 3 and the second diffraction grating 4 are formed on the index substrate 6b on the outer surface 6b-2. It is preferable to have. When the package 6a and the index substrate 6b are combined, the package 6a and the index substrate 6b are aligned so that the alignment patterns 7a and 7b overlap each other.
By having the alignment patterns 7a and 7b as described above, the index substrate 6b, particularly the center of the light deflection element 5, can be easily positioned with respect to the optical axis 1a of the light emitting element 1. Therefore, also from this point, the optical encoder 104 of the present embodiment can improve detection accuracy as compared with the conventional one.

  The optical encoder sensor 10A is manufactured by aligning in this way and combining the package 6a and the index substrate 6b.

  As described above, the light emitting element 1 and the light receiving element 2 are mounted on the package 6a constituting the sensor unit 6, and the first diffraction grating 3, the second diffraction grating 4, and the light deflection element 5 are mounted on the index substrate 6b. Is formed. Therefore, by combining the package 6a and the index substrate 6b as described above, the optical encoder sensor 10A can be easily formed, and the optical encoder sensor can be made thinner. it can. Further, since the light deflection element 5 is inserted, it is possible to increase the amount of received light as compared with the conventional case, and it is possible to drive the light emitting element with lower power consumption. Therefore, energy saving can be achieved. Further, since the optical deflection element 5 is integrally formed with the index substrate 6b, the optical axis alignment in the production process of the optical deflection element 5 and the first diffraction grating 3 is not required, and the assembly is facilitated.

Next, the optical scale 30 will be described.
The optical scale 30 is a member that extracts, that is, reflects, light having a specific frequency from the light emitted from the first diffraction grating 3. As shown in FIG. 7, such an optical scale 30 has an optical pattern 31 formed of a reflecting portion 31a that reflects light irradiated from the first diffraction grating 3 and a non-reflecting portion 31b that does not reflect. Then, it is attached to a detected object whose movement amount is to be detected. In the present embodiment, the optical scale 30 moves along the arrangement direction 30b (FIG. 6B) of the first diffraction grating 3 and the second diffraction grating 4, and for example, in FIG. , Move along the direction perpendicular to the page.

The reflective portion 31a of the optical scale 30 can be formed by forming a light reflective film on a transparent glass or resin substrate by lithography or the like, for example. The non-reflective portion 31b can be formed as it is with the material of the optical scale 30, and an antireflection film may be formed on the material to improve the S / N ratio.
Moreover, the optical scale 30 may form the non-reflective part 31b by forming a light absorption film on a light-reflective substrate, or roughening by laser irradiation, for example. As described above, in the optical scale 30, as long as the reflecting portion 31a and the non-reflecting portion 31b are formed, the base material, the forming method and the shape of the reflecting portion 31a and the non-reflecting portion 31b are particularly limited. Not.

Furthermore, the optical scale 30 is not formed by forming a V-shaped protrusion shape on the light irradiation surface of the scale substrate as shown in FIG. 8, or forming a V-shaped groove shape as shown in FIG. The reflecting portion 31b may be formed by forming a reflecting portion 31b and applying a metal or dielectric multilayer film to a flat portion other than the non-reflecting portion 31b in the light irradiation surface.
In the optical scale 30 shown in FIGS. 8 and 9, the light incident on the flat reflecting portion 31a is directed toward the light receiving element 2 by specular reflection. In the non-reflecting portion 31b having a V-projection shape or a V-groove shape, the reflection direction Changes to a direction other than the light receiving element 2.

  Further, when the scale base material is a transparent material, the V protrusion shape or the V groove shape of the non-reflecting portion 31b may be processed on the front and back of the scale base material, that is, the light irradiation surface and the opposite surface. . 8 and 9 show the case where the inclination angle of the V-projection shape or V-groove shape of the non-reflective portion 31b is 45 degrees, the light beam reflected by the V-projection shape or V-groove shape is the light receiving element 2. The inclination angle is not particularly limited as long as the angle does not enter the beam.

  Next, the movement amount detection unit 70 is a means for detecting the movement amount of the optical scale 30 by electrically connecting the light receiving element 2 and converting the intensity of the light received by the light receiving element 2 into an electric signal. is there.

Next, the operation of the optical encoder in the first embodiment, that is, the principle of detecting the movement of the optical scale 30 will be described.
A light beam from a light source having a low coherence such as a light emitting element 1, for example, an LED, passes through the light deflecting element 5 as described above, that is, deflected by the condensing part 5a and not deflected by the flat part 5b. The light passes through the first diffraction grating 3 corresponding to the first diffraction grating, and a secondary light source distribution is generated on the first diffraction grating 3.

  The optical pattern 31 on the optical scale 30 corresponding to the second diffraction grating functions as a spatial frequency filter having a certain optical transfer function, and is generated on the first diffraction grating 3. In the next light source distribution, only a specific spatial frequency component is extracted and the light is reflected. This reflected light is imaged on the second diffraction grating 4 corresponding to the third diffraction grating.

  Here, the optical gap between the first diffraction grating and the second diffraction grating is Z2, the optical gap between the second diffraction grating and the third diffraction grating is Z2, and the light emitting element 1 Where the wavelength of the emitted light is λ, the pitch of the first diffraction grating 3 is P1, and the pitch of the optical pattern 31 on the optical scale 30 is P2, the pitch P1 is set on the second diffraction grating 4 when the following equation is satisfied. An optical pattern is formed.

(1 / Z1) + (1 / Z2) = λ / (n × (P2) ² ) (1)

  m × P1 = P2 × (Z1 + Z2) / Z1 (2)

  Here, n and m are natural numbers.

  The light transmitted through the second diffraction grating 4 is converted into an electric signal by the light receiving element 2. When the first diffraction grating 3, that is, the optical encoder sensor 10A and the optical scale 30 move relatively along the arrangement direction 30b, the amount of light received detected by the light receiving element 2 changes. The movement amount detector 70 detects this change in the amount of received light, and thereby the relative position between the optical encoder sensor 10A and the optical scale 30 can be detected.

As described above, according to the optical encoder 101 of the first embodiment, the light emitted from the light emitting element 1 enters the light deflection element 5. At this time, among the light rays emitted from the light emitting element 1 by the light condensing part 5a of the light deflecting element 5, the peripheral light having a large angle with respect to the optical axis can be irradiated onto the first diffraction grating 3. . Therefore, the utilization efficiency of the emitted light of the light emitting element 1 can be improved.
Further, as already described, since the light deflection element 5 is integrally formed on the index substrate 6b on which the first diffraction grating 3 and the second diffraction grating 4 are formed, the first diffraction grating 3 and the second diffraction grating 5 are formed. The alignment between the grating 4 and the light deflecting element 5 is not required, so that the detection accuracy can be improved as compared with the conventional case, and the assembly becomes easier.

Embodiment 2. FIG.
FIG. 10 is a sectional view showing the optical encoder 102 according to the second embodiment. The basic configuration of the optical encoder 102 is the same as that of the optical encoder 101 in the first embodiment, but the condensing unit 5a of the optical deflection element 5 in the optical encoder sensor 10A is replaced with the optical encoder of the present embodiment. The optical encoder sensor 10B 102 is different in that it is formed of a Fresnel lens. Other configurations and detection principles are the same as those in the first embodiment, and only different components will be described below, and description of the same components will be omitted.

  FIG. 11 is an enlarged view of the optical deflection element 51 provided in the optical encoder sensor 10B in the optical encoder 102 according to the second embodiment. The light deflection element 51 is composed of a condensing part 51a composed of a part of a Fresnel lens and a flat part 51b. Here, the condensing unit 51 a corresponds to the condensing unit 5 a of the optical deflection element 5 in the optical encoder sensor 10 </ b> A of the first embodiment, and the flat part 51 b corresponds to the flat part 5 b of the optical deflection element 5. . That is, among the light beams from the light emitting element 1, the light beam that has entered the flat portion 51 b passes through the light deflecting element 51 as it is without changing the direction of the light beam, and is irradiated onto the first diffraction grating 3. In addition, among the light beams from the light emitting element 1, the light beam that has entered the light collecting unit 51 a is irradiated onto the first diffraction grating 3 while changing the direction of the light beam to the inside with respect to the optical axis.

  As described above, according to the optical encoder 102 of the second embodiment, among the light beams emitted from the light emitting element 1, the peripheral light having a large angle with respect to the optical axis is also reflected by the first diffraction grating 3 by the light deflecting element 51. It is possible to irradiate the light upward, and the utilization efficiency of the emitted light of the light emitting element 1 can be improved. The effects achieved by the optical encoder 101 according to the first embodiment can also be achieved by the optical encoder 102 according to the second embodiment. Furthermore, the optical deflection sensor 51 is formed of a Fresnel lens, and the condensing part 51a is a part of the Fresnel lens, so that the optical encoder sensor 10B can be compared with the optical encoder sensor 10A of the first embodiment. Can be made thinner.

  In the second embodiment, the condensing part 51a of the light deflection element 51 is a part of the Fresnel lens, but it may be a Fresnel zone plate. Moreover, a prism array may be used like the light deflection element 51A shown in FIG. 12 and the light deflection element 51B shown in FIG.

  Further, as described above with reference to FIG. 3 and the like, the light deflection elements 51, 51A, and 51B also have, for example, an oval planar shape, and in the direction of the arrow 30a, the light converging part 51a and the flat part 51b. The shape may be such that only the light condensing part 51a is formed at both ends in the arrangement direction 30b. Moreover, the condensing part 51a and the flat part 51b may be formed in the direction of the arrow 30a, and the surface of the both ends in the arrangement direction 30b may be a cylindrical shape made into the flat surface 51c. Moreover, the condensing part 51a may be a different spherical surface or an aspherical surface in the both end portions and the direction of the arrow 30a.

Embodiment 3 FIG.
FIG. 14 is a sectional view showing the optical encoder 103 according to the third embodiment. The basic configuration of the optical encoder 103 is the same as that of the optical encoder 101 in the first embodiment, but the optical deflection element 5 in the optical encoder sensor 10A is replaced with the optical encoder in the optical encoder 103 in the third embodiment. The encoder sensor 10 </ b> C is different in that the encoder sensor 10 </ b> C is formed by a concave lens-shaped light deflection element 52. Since the other configuration and detection principle of the optical encoder 103 are the same as those in the first embodiment, only different components will be described below, and description of the same components will be omitted.

  FIG. 15 is an enlarged view of the optical deflection element 52 in the optical encoder sensor 10C provided in the optical encoder 103 according to the third embodiment. The light deflection element 52 includes a diffusing portion 52c made of a part of a spherical or aspherical concave lens. In the present embodiment, the planar shape of the diffusion portion 52c is a circle. Of the light rays emitted from the light emitting element 1, light rays near the optical axis are incident on the diffusing portion 52c and irradiated onto the first diffraction grating 3 while changing the direction of the light rays so as to diverge with respect to the optical axis. On the other hand, the light rays far from the optical axis that do not enter the diffusing portion 52c out of the light rays emitted from the light emitting element 1 pass through the flat inner surface 6b-1 of the index substrate 6b and are directly irradiated to the first diffraction grating 3. .

  As described above, according to the optical encoder sensor 10C in the third embodiment, the light near the optical axis out of the light emitted from the light emitting element 1 is incident on the diffusing unit 52c and is relative to the optical axis. The direction of the light beam can be changed so as to diverge. Therefore, a light beam near the center of the optical axis having a high light intensity can be used, and light utilization efficiency can be improved. In addition, the effects exhibited by the optical encoder 101 of the first embodiment can also be achieved by the optical encoder 103 of the third embodiment.

  Further, the concave lens forming the light deflection element 52 may be a part of a Fresnel lens or a Fresnel zone plate. In this case, it is possible to reduce the thickness of the entire index. The light deflection element 52 also has, for example, an oval planar shape, forms concave condensing portions 52c along the arrangement direction 30b, and is positioned at both ends in the arrangement direction 30b. The surface parallel to the surface may be a flat cylindrical shape, or may be a concave surface at both ends.

Embodiment 4 FIG.
FIG. 16 is a cross-sectional view showing the optical encoder 104 in the fourth embodiment. The basic configuration of the optical encoder 104 is the same as that of the optical encoder 101 in the first embodiment, but the optical deflection element 5 in the optical encoder sensor 10A is replaced by the optical encoder in the optical encoder 104 of the present embodiment. The sensor 10 </ b> D is different in that it is formed by the light deflection element 53. The light deflection element 53 is formed of a diffusing portion 53c formed from a spherical or aspheric concave lens and a condensing portion 53a formed from a part of a Fresnel lens. In the present embodiment, the planar shape of the light deflection element 53 is circular. Since the other configuration and detection principle in the optical encoder 104 are the same as those in the first embodiment, only different components will be described below, and description of the same components will be omitted.

  FIG. 17 is an enlarged view of the light deflection element 53 according to the fourth embodiment. In the light deflecting element 53, the light rays in the vicinity of the optical axis out of the light rays emitted from the light emitting element 1 enter the concave lens-shaped diffusing portion 53c and change the direction of the light rays so as to diverge with respect to the optical axis. Irradiation onto the grating 3. In addition, out of the light rays emitted from the light emitting element 1, the light rays incident on the Fresnel lens-shaped condensing portion 53 a are irradiated onto the first diffraction grating 3 while changing the direction of the light rays to the inner side with respect to the optical axis.

  As described above, according to the optical encoder 104 of the fourth embodiment, the light beam in the vicinity of the optical axis out of the light emitted from the light emitting element 1 is diverged with respect to the optical axis by the diffusion unit 53c. The outer peripheral light having a large angle with respect to the optical axis can be changed inward with respect to the optical axis by the condensing part 53a. Therefore, in the fourth embodiment, the amount of light applied to the first diffraction grating 3 is larger than in the first to third embodiments, and the light utilization efficiency can be further improved. In addition, the effects achieved by the optical encoder 101 according to the first embodiment can also be achieved by the optical encoder 104 according to the fourth embodiment.

  In the fourth embodiment, the diffusing unit 53c of the light deflecting element 53 is configured by a spherical or aspherical concave lens, and the condensing unit 53a is configured by a part of a Fresnel lens. As long as it has a lens, the diffusing unit 53c and the condensing unit 53a may be a simple lens, a Fresnel lens, or a Fresnel zone plate. By configuring all of the diffusing unit 53c and the condensing unit 53a with a Fresnel lens or a Fresnel zone plate, the thickness of the index substrate 6b can be reduced.

  The light deflection element 53 has a lens system concentrically with respect to the optical axis of the light-emitting element 1, but has, for example, an oval planar shape, and in the direction of the arrow 30a, the diffusion portion 53c and The condensing part 53a may be formed, and the end surface in the arrangement direction 30b may be a flat cylindrical shape, or the end part in the arrangement direction 30b may be constituted by only the condensing part 53a.

  In the above-described fourth embodiment, the light deflection element 53 is configured to have a lens system concentrically with respect to the optical axis of the light emitting element 1, but like the light deflection element 53A shown in FIG. The light emitting element 1 may be formed of a convex lens 53d formed so as to be symmetric with respect to the optical axis 1a, that is, the optical axis 1a portion is recessed. Of course, the convex lens 53d may be formed of a Fresnel lens or a Fresnel zone plate.

  By arranging the lens symmetrically with respect to the optical axis 1a of the light-emitting element 1 in this way, both the strong light near the optical axis 1a and the peripheral light having a large divergence angle with respect to the optical axis 1a are obtained. It is possible to irradiate one diffraction grating 3. Therefore, the light use efficiency can be improved.

Embodiment 5 FIG.
FIG. 19 is an enlarged view showing the optical deflection element 53 provided in the optical encoder 105 according to the fifth embodiment. The basic configuration of the optical encoder 105 is the same as that of the optical encoder 104 in the fourth embodiment, and the optical deflection element 53 in the optical encoder sensor 10D of the optical encoder 105 is also the optical encoder in the fourth embodiment. The same configuration as the light deflection element 53 of 104 is adopted. However, in the optical encoder 104A according to the fifth embodiment, the center axis of the light deflecting element 53, that is, the optical axis 53e is the arrow of the first diffraction grating 3 and the second diffraction grating 4 with respect to the optical axis 1a of the light emitting element 1. It differs only in that it is displaced in the direction of 30a. Other configurations and detection principles in the optical encoder 105 are the same as those in the fourth embodiment.

  With this configuration, it is possible to collect light near the center having a high light intensity in one of the two light receiving elements 4. Therefore, since the area of the light receiving element 4 can be reduced, the cost can be reduced. For example, one of the two optical patterns 31 of the optical scale 30 is a random code pattern such as an M series that does not require the first diffraction grating 3 or an optical pattern in which an origin pattern is configured, and the other is 3 In the case of an incremental signal detection optical pattern using a single diffraction grating, the first diffraction grating 3 is not necessary in one optical pattern in which a random code pattern or an origin pattern is formed. In the light receiving element 4 that receives the reflected light, a sufficient amount of light can be obtained. On the other hand, in the light receiving element 4 that receives the reflected light from the other optical pattern for detecting the incremental signal, insufficient light quantity becomes a problem. Therefore, in such a case, the optical axis 1a of the light emitting element 1 is shifted toward the incremental signal detecting optical pattern side with respect to the central axis 53e of the optical deflecting element 53, whereby the incremental signal detecting optical pattern is The amount of light received by the light receiving element 4 that receives the reflected light can be increased.

  The configuration in the fifth embodiment can be applied to any of the first to fourth embodiments described above.

Embodiment 6 FIG.
FIG. 20 is a cross-sectional view showing the optical encoder 106 according to the sixth embodiment. The basic configuration of the optical encoder 106 is the same as the configuration of the optical encoder 104 in the fourth embodiment described above. However, the optical encoder sensor 10E provided in the optical encoder 106 of the sixth embodiment has a package 6a. 1 except that a light shielding plate 6 a-4 is provided between the light emitting element 1 and the light receiving element 2. Other configurations and detection principles in the optical encoder 106 are the same as those in the fourth embodiment.

  For example, the light shielding plate 6a-4 may be formed in a circular shape around the light emitting element 1 on the bottom surface 6a-2 of the package 6a, or two linear light shielding plates may be provided side by side.

  With this configuration, the light rays reflected from the surface of the index substrate 6b and directly incident on the light receiving element 2 out of the light rays emitted from the light emitting element 1 can be shielded by the light shielding plate 6a-4. The / N ratio can be improved.

  In the sixth embodiment, the light shielding plate 6a-4 is provided on the package 6a. However, like the optical encoder sensor 10F shown in FIG. 21, the light shielding plate 6b- is formed on the inner surface 6b-1 of the index substrate 6b. 4 may be erected. Here, since the light shielding plate 6b-4 is a portion corresponding to the above-described light shielding plate 6a-4, and the index substrate 6b is a transparent member, the inner surface of the light shielding plate 6b-4 on the light emitting element 1 side absorbs light. The film 6b-5 may be applied.

In the configuration of the optical encoder sensor 10E shown in FIG. 20, a slight gap is formed between the light shielding plate 6a-4 of the package 6a and the inner surface 6b-1 of the index substrate 6b, and light is transmitted from the gap. There is a possibility of direct incidence on the light receiving element 2. Also in the configuration of the optical encoder sensor 10F shown in FIG. 21, there is a slight gap between the light shielding plate 6b-4 standing on the index substrate 6b and the bottom surface 6a-2 of the package 6a. However, in the configuration of the optical encoder sensor 10F shown in FIG. 21, the light emitting surface of the light emitting element 1 is located at a position far higher than the bottom surface 6a-2 and the traveling direction of the emitted light is larger than the gap. Since the gap is positioned in the opposite direction, the light directly incident on the light receiving element 2 can be completely prevented.
The configuration of the sixth embodiment can be applied to any of the first to fifth embodiments described above.

  In the optical encoders 101 to 106 according to the first to sixth embodiments described above, specific examples of the linear encoder that linearly moves and detects the movement and movement amount are shown. However, the optical encoders 101 to 106 can also be configured as a rotary encoder in which the optical scale 30 rotates around the rotation axis and detects the rotation and the rotation amount. can get.

DESCRIPTION OF SYMBOLS 1 Light emitting element, 1a Optical axis, 2 Light receiving element, 3rd 1st diffraction grating, 4th 2nd diffraction grating,
5 Light deflection element, 5a Condensing part, 6 Sensor unit,
6a package, 6b index board, 6a-4, 6b-4 shading plate,
7a Package side alignment pattern,
7b Index board side alignment pattern,
10A to 10F optical encoder sensor,
30 optical scale,
51, 52 Light deflection element, 52c Diffusion part, 53 Light deflection element,
53a light collecting part, 53c diffusion part,
70 Movement amount detection unit,
101-106 Optical encoder.

Claims (12)

A light emitting element;
A first diffraction grating through which the emitted light of the light emitting element passes and generates a periodic light quantity distribution from the emitted light;
A second diffraction grating through which reflected light of a specific frequency reflected by an optical scale among light passing through the first diffraction grating is transmitted;
A light receiving element that receives light that has passed through the second diffraction grating;
A sensor unit that integrally forms the light emitting element, the light receiving element, the first diffraction grating, and the second diffraction grating,
The sensor unit integrally includes a light deflection element that deflects the light emitted from the light emitting element between the light paths of the light emitting element and the first diffraction grating ,
The optical deflection sensor according to claim 1, wherein the light deflection element has a diffusion portion for diffusing light emitted from the light emitting element . A light emitting element;
A first diffraction grating through which the emitted light of the light emitting element passes and generates a periodic light quantity distribution from the emitted light;
A second diffraction grating through which reflected light of a specific frequency reflected by an optical scale among light passing through the first diffraction grating is transmitted;
A light receiving element that receives light that has passed through the second diffraction grating;
A sensor unit that integrally forms the light emitting element, the light receiving element, the first diffraction grating, and the second diffraction grating,
The sensor unit integrally includes a light deflection element that deflects the light emitted from the light emitting element between the light paths of the light emitting element and the first diffraction grating ,
The optical deflection element includes an optical condensing unit that condenses the light emitted from the light-emitting element onto the first diffraction grating, and a diffusion unit that diffuses the light emitted from the light-emitting element. Sensor. The optical encoder sensor according to claim 2 , wherein at least one of the condensing unit and the diffusing unit is configured by a part of a spherical or aspherical concave lens or a convex lens. The optical encoder sensor according to claim 2 , wherein at least one of the condensing unit and the diffusing unit is configured by a part of an aspherical Fresnel lens or a Fresnel zone plate. The optical encoder sensor according to any one of claims 2 to 4 , wherein the condensing unit is configured by a slope. The light deflection element is molded integrally with an index substrate on which the first diffraction grating and the second diffraction grating are formed, and the sensor unit includes a package on which the light emitting element and the light receiving element are mounted, and the index substrate. The optical encoder sensor according to claim 1, wherein the optical encoder sensor is formed by being united. The package has a package-side alignment pattern that is a reference for mounting the light emitting element and the light receiving element, and the index substrate is a reference for molding the first diffraction grating and the second diffraction grating. And has an index side alignment pattern
The sensor for an optical encoder according to claim 6 , wherein the sensor unit is combined by aligning the package side alignment pattern and the index side alignment pattern. The deflection element has two lenses arranged symmetrically with respect to the optical axis of the light emitting device, an optical sensor encoder according to any one of claims 1 7. The deflection element is configured in cylindrical shape, an optical sensor encoder according to any one of claims 1 to 8. The light emitting element and the light deflecting element is arranged offset to the optical axis of the optical axis and the light deflecting element of the light emitting device, a sensor for an optical encoder according to any one of claims 1 9 . The sensor for an optical encoder according to any one of claims 1 to 10 , wherein the sensor unit includes a light shielding plate between the light emitting element and the light receiving element. A sensor for an optical encoder according to any one of claims 1 to 11 ,
An optical scale that takes out light of a specific frequency out of light that has passed through the first diffraction grating included in the optical encoder sensor, and reflects the light to the optical encoder sensor;
A detection unit that is electrically connected to a light receiving element included in the optical encoder sensor and detects a relative movement between the optical encoder sensor and the optical scale;
An optical encoder comprising:

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