JP7139177B2 - optical angle sensor - Google Patents

Description

The present invention relates to optical angle sensors.

Conventionally, a light source that emits light, a reflection means that rotates about a predetermined axis as a measurement axis and reflects the light emitted from the light source, a detection means that detects the light emitted from the light source, and detection from the detection means and a calculation means for calculating an angle based on the received signal.
Such an optical angle sensor can detect angles with high resolution, can detect angles in a wide range of 1 degree or more, does not have a scale, and can detect angles based on a reference angle. preferable. Here, the reference angle is a predetermined angle corresponding to the origin (absolute value) that serves as a reference when detecting the angle.

Known angle detection methods include an incremental method (INC method) and an absolute method (ABS method).
In the INC method, for example, a constant-pitch incremental pattern (INC pattern) provided on a scale is continuously detected, and the number of passed INC patterns is counted up or down to detect the angular displacement of the object to be measured. method.
The ABS method is a method of detecting the absolute value of the angular displacement of the object to be measured by specifying, for example, a reference angle that is the origin by a predetermined method, and combining the angle detected by the INC method with the reference angle. . As another ABS method, for example, there is a method of detecting an absolute value of angular displacement in a measurement object by detecting an absolute pattern (ABS pattern) randomly provided on a scale and analyzing the ABS pattern.

For example, the optical rotary encoder described in Patent Document 1 includes a rotating slit plate (scale), a fixed slit plate, a plurality of LEDs, and a plurality of light receiving elements. The rotating slit plate and the fixed slit plate have slits for A-phase signal and B-phase signal, which are angle detection slits for detecting angles by the INC method, and C-phase signal slits, which are slits for rotor magnetic pole position detection. and a Z-phase signal slit that is a slit for detecting a predetermined rotation angle during one rotation of the optical axis of the optical rotary encoder, that is, a reference angle (origin). The optical rotary encoder can detect a high-resolution angle based on the signals detected from the A-phase signal slit and the B-phase signal slit. can be detected. Also, the reference angle can be specified based on the signal detected from the Z-phase signal slit. The optical rotary encoder can detect the absolute value of the angular displacement of the measurement object by combining this reference angle with the signals detected from the A-phase signal slit and the B-phase signal slit.

Further, for example, the rotation angle detection device described in Patent Document 2 detects a collimated light beam generated by collimating divergent laser light emitted from a short-wave laser light source (light source) by a reflector (reflector) mounted on the object to be measured. means) and is reflected from the reflecting portion, is collected by an objective lens to measure the angle. The light receiving element for measurement is arranged so that the center of the light spot obtained by condensing the light flux for measurement is positioned on the boundary between the sensitive band and the non-sensitive band of the light receiving element for measurement, and a positioning stage installed in the The rotation angle detection device uses a positioning stage to move the measuring object so that the center of the light spot remains on the boundary between the sensitive band and the non-sensitive band of the light receiving element for measurement when the object to be measured (measuring object) rotates. The position of the light receiving element is controlled, and the rotation angle of the object to be measured is obtained based on the position control information. The rotation angle detection device uses the boundary between the sensitive band and the non-sensitive band of the light-receiving element for measurement as a reference angle, and can perform high-resolution angle detection based on this reference angle without using a scale.

Further, for example, the shape measuring apparatus described in Patent Document 3 measures the shape of the surface to be measured at a position facing the measuring head portion that moves substantially parallel to the surface to be measured (reflecting means) and the measuring head portion. and a signal processing unit (computing means) for measuring the amount that changes with the parallel movement of the head unit and the surface to be measured. The measurement head includes an irradiation light forming means (light source) for irradiating the surface to be measured with light composed of multiple light beams in the same phase, and an interference fringe forming means for forming interference fringes by diffracting the reflected light from the surface to be measured. and a light-receiving element array (light-receiving means) for receiving light of interference fringes and outputting light-receiving signals. The signal processing unit detects a change in shape of the surface to be measured from the displacement of the interference fringes based on the light receiving signal from the light receiving element array. As a result, the shape measuring apparatus can detect angles in a wide range, and can detect angles with high resolution without using a scale.

JP-A-6-11362 JP 2017-133892 A JP 2005-274429 A

However, the optical rotary encoder described in Patent Document 1 requires a rotary slit plate, which is a disk-shaped scale, in order to obtain the reference angle. As a result, the optical rotary encoder has problems in that manufacturing of the rotary slit plate is costly and misalignment may occur when the rotary slit plate is attached to the output shaft of the servomotor. Moreover, the rotation angle detection device described in Patent Document 2 has a problem that the allowable rotation angle of the object to be measured is within 1 degree, and the detectable range is very narrow. Furthermore, the shape measuring apparatus described in Patent Document 3 has a problem that the reference angle with respect to the surface to be measured cannot be specified.

An object of the present invention is to provide an optical angle sensor that can detect angles with high resolution, can detect angles over a wide range, does not have a scale, and can specify a reference angle. That is.

The optical angle sensor of the present invention comprises a light source that emits light, a reflecting means that rotates about a predetermined axis as a measurement axis and reflects the light emitted from the light source, and a detector that detects the light emitted from the light source. and computing means for computing an angle based on a signal detected by the detecting means, wherein the detecting means comprises a plurality of diffraction gratings for diffracting light into a plurality of diffracted lights, and a light source. a light receiving means for receiving light emitted from the light receiving means, the light receiving means includes a first light receiving section for receiving predetermined diffracted light among the plurality of diffracted lights; a second light receiving section for receiving the diffracted light, the calculating means includes a signal detecting section for detecting a signal for calculating an angle based on the light received from the first light receiving section; The absolute value of the angle is calculated based on the signal detected by the signal detection unit and the reference angle specified by the identification unit, and the identification unit that identifies the reference angle that is used as the reference when calculating the angle based on the light. and an angle calculator.

According to the present invention, the calculation means detects a signal for calculating the angle by the signal detection section based on the light received from the first light receiving section, and the specific section detects a signal for calculating the angle based on the light received from the second light receiving section. To specify a reference angle that serves as a reference when calculating an angle, and to calculate the absolute value of the angle in the angle calculation unit based on the signal detected by the signal detection unit and the reference angle specified by the specification unit. , the reference angle can be specified without using a scale, and the angular displacement of the object to be measured can be detected with high accuracy. Therefore, the optical angle sensor can detect angles with high resolution, can detect angles in a wide range, does not have a scale, and can specify a reference angle.

Here, the optical angle sensor detects a signal for calculating an angle without using a scale, and in order to specify a reference angle that serves as a reference when calculating an angle, a plurality of corresponding A light source must be provided. Further, when the optical angle sensor is provided with a plurality of light sources, the temperature characteristics due to the heat generated by each light source and the light quantity characteristics depending on the intensity of the light quantity may differ. For this reason, the plurality of light sources may cause variations in the characteristics of light received by the respective light receiving units of the light receiving means, which may cause errors.

However, according to the present invention, the detecting means in the optical angle sensor includes a plurality of diffraction gratings for diffracting the light emitted from the light source into a plurality of diffracted lights, and the light-receiving means diffracts the plurality of diffracted lights into a predetermined diffraction pattern. Since the first light receiving section for receiving light and the second light receiving section for receiving diffracted light other than the predetermined diffracted light received by the first light receiving section are provided, a single light source is used without providing a plurality of light sources. A signal for calculating an angle can be detected, and a reference angle that serves as a reference for calculating the angle can be specified. Therefore, the optical angle sensor can achieve cost reduction and space saving. In addition, by using one light source, there is no error factor due to temperature characteristics and light amount characteristics that occur when a plurality of light sources are provided, so the optical characteristics are uniformized by the first light receiving part and the second light receiving part provided in the light receiving means. can be

At this time, it is preferable that the predetermined diffracted light beams received by the first light receiving unit are two diffracted light beams.

Here, when the first light receiving section receives one diffracted light, the signal detection section detects a signal for calculating the angle from the one diffracted light. If the light intensity of one diffracted beam is small, the signal detection section may not be able to detect the signal for calculating the angle. Also, when the first light receiving section receives two or more diffracted lights, the signal detecting section detects a signal for calculating the angle from the plurality of diffracted lights. When the signal detection unit detects a signal for calculating an angle from a plurality of diffracted lights, noise may occur in the signal for calculating the angle.

However, according to such a configuration, the signal detection section in the calculation means can detect the angle based on the two diffracted beams, so that the signal for calculating the angle is detected from one diffracted beam. It is possible to suppress the problem that the signal cannot be detected in some cases, and the occurrence of noise when detecting the signal for calculating the angle from a plurality of diffracted lights. Therefore, the optical angle sensor can calculate the absolute value of the angle with higher accuracy than when detecting a signal for calculating the angle based on one diffracted beam or a plurality of diffracted beams.

At this time, it is preferable that the second light receiving section receives the light reflected by the reflecting means.

According to such a configuration, when the reflecting means is installed on the object to be measured, for example, it rotates with the turning of the object to be measured. The reference angle can be specified more reliably than in the case.

At this time, it is preferable that the first light receiving section and the second light receiving section receive light through the half mirror.

According to such a configuration, the light emitted from the light source, for example, is split into two lights by the half mirror. As a result, one of the light beams is received by the first light receiving portion and used for detecting a signal for calculating the angle by the signal detecting portion, and the other light beam is received by the second light receiving portion and the reference angle is specified by the specifying portion. can do. Therefore, the optical angle sensor can improve the degree of freedom in design. In addition, since the light emitted from the light source is split into two by the half mirror, it is possible to detect the signal for calculating the angle and specify the reference angle using one light source without providing a plurality of light sources. can.

In this case, the reflecting means preferably includes a reflecting portion that reflects light and a diffraction grating portion that diffracts the light into a plurality of diffracted beams.

According to such a configuration, the reflecting means includes the reflecting portion that reflects light and the diffraction grating portion that diffracts the light into a plurality of diffracted beams. You can adjust the light you want. Here, adjustment of light means diverging light in multiple directions or converging light in one direction. Therefore, since the optical angle sensor can adjust the light according to the arrangement of the first light receiving section and the second light receiving section, the degree of freedom in design can be improved.

At this time, it is preferable that the diffraction grating section has a plurality of gratings arranged side by side along a direction parallel to the measurement axis.

According to such a configuration, the diffraction grating section in the reflecting means has a plurality of gratings arranged in parallel along the direction parallel to the measurement axis. can be converged in a given direction. Therefore, since the optical angle sensor can converge light according to the arrangement of the first light receiving section and the second light receiving section, the degree of freedom in design can be improved.

Moreover, it is preferable that the diffraction grating section has a plurality of gratings arranged side by side along a direction orthogonal to the measurement axis on the reflecting surface of the reflecting means.

According to such a configuration, the diffraction grating section in the reflecting means has a plurality of gratings arranged side by side along the direction orthogonal to the measurement axis on the reflecting surface of the reflecting means. The light received by the light receiving section can be diverged in a predetermined direction. Therefore, since the optical angle sensor can diverge light according to the arrangement of the first light receiving section and the second light receiving section, the degree of freedom in design can be improved.

At this time, it is preferable that the second light receiving section is arranged at a position where the light reflected by the reflecting means converges.

According to such a configuration, the second light receiving section is arranged at a position where the light reflected by the reflecting means converges. can receive light for Therefore, the optical angle sensor can be designed more easily than when it has a plurality of second light receiving sections. In addition, since the optical angle sensor does not need to have a plurality of second light receiving sections, it is possible to reduce costs compared to the case of having a plurality of second light receiving sections.

At this time, the specifying unit stores a reference angle specifying value for specifying the reference angle, and compares the position of the light irradiated to the light receiving surface of the second light receiving unit with the reference angle specifying value. It is preferred to specify an angle.

According to such a configuration, the specifying unit collates the position of the light irradiated to the light receiving surface of the second light receiving unit with the reference angle specifying value for specifying the reference angle stored in advance in the specifying unit, for example. Since the reference angle is specified by doing so, the reference angle can be easily specified based on the light with which the second light receiving section is irradiated.

1 is a perspective view showing an optical angle sensor according to a first embodiment; FIG. Block diagram showing the optical angle sensor The perspective view which shows the optical angle sensor which concerns on 2nd Embodiment. Block diagram showing the optical angle sensor A perspective view showing an optical angle sensor according to a third embodiment. Block diagram showing the optical angle sensor The perspective view which shows the optical angle sensor which concerns on 4th Embodiment. Block diagram showing the optical angle sensor

[First embodiment]
A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG.
FIG. 1 is a perspective view showing the optical angle sensor according to the first embodiment.
As shown in FIG. 1, the optical angle sensor 1 includes a light source 2 that emits light, a reflecting means 3 that rotates around a predetermined axis as a measurement axis and reflects the light emitted from the light source 2, and a light source 2. and a detection means 4 for detecting light emitted from. The detector 4 includes a plurality of diffraction gratings 5 and 6 that diffract the light emitted from the light source 2 into a plurality of diffracted lights, and a light receiver 7 that receives the light emitted from the light source 2 . The multiple diffraction gratings 5 and 6 have a first diffraction grating 5 and a second diffraction grating 6 .
The optical angle sensor 1 is provided inside a measuring instrument that measures a rotating object.

The light source 2 irradiates parallel light having a constant width toward one surface of the first diffraction grating 5 . The light source 2 is, for example, an LED (Light Emitting Diode). Note that the light source 2 is not limited to an LED, and may be any light source.
The reflecting means 3 is attached to a rotating measuring object, and rotates about the Y-axis as a measuring axis. The reflecting means 3 has a reflecting surface 30 facing the detecting means 4 . The reflecting surface 30 is a mirror that reflects the light emitted from the light source 2 . It should be noted that the reflecting surface 30 need not be a mirror and may be of any type as long as it can reflect light.

In the following description, the measurement axis direction parallel to the measurement axis (Y-axis) is defined as the Y direction, and the direction perpendicular to the Y axis on the reflecting surface 30 of the reflection means 3 is defined as the X axis. A direction parallel to is defined as an orthogonal direction (X direction), and a direction orthogonal to the X direction and the Y direction is defined as a Z direction.

The detecting means 4 detects the absolute value of the tilt angle of the reflecting means 3 from a plurality of diffracted lights that change according to the rotation of the object to be measured to which the reflecting means 3 is attached.
Here, the plurality of diffracted lights includes diffracted light that travels in the same direction as the optical axis of the light emitted from the light source 2, diffracted light that travels on both sides of the optical axis at a predetermined diffraction angle, and diffracted light that travels on both sides of the optical axis. and diffracted light traveling at a diffraction angle larger than a predetermined diffraction angle.
Assuming that the diffracted light traveling in the same direction as the optical axis is the 0th-order diffracted light, the plurality of diffracted lights are ordered as ±1st-order diffracted lights and ±2nd-order diffracted lights in the direction in which the diffraction angle increases with the 0th-order diffracted light as a reference. be able to.
The detector 4 detects signals mainly from interference fringes generated by the ±1st order diffracted lights. In the following description, ±1st-order diffracted light may be referred to as signal diffracted light 111, and light other than 0th-order diffracted light or ±1st-order diffracted light may be referred to as reference angle specific light 100. FIG.

The first diffraction grating 5 and the second diffraction grating 6 are made of translucent glass. It should be noted that the first diffraction grating 5 and the second diffraction grating 6 may be made of any translucent member without being limited to glass.
The first diffraction grating 5 is a transmissive diffraction grating having a plurality of gratings 50 arranged side by side along the X direction. The first diffraction grating 5 diffracts and transmits parallel light from the light source 2 directed toward the reflecting means 3 .

The second diffraction grating 6 is a reflective diffraction grating having a plurality of gratings 60 arranged side by side along the X direction. The second diffraction grating 6 diffracts the light reflected from the reflecting means 3 and reflects a plurality of diffracted lights toward the reflecting means 3 . Further, the second diffraction grating 6 has a substantially rectangular opening 61 at substantially the center. The opening 61 irradiates the 0th-order diffracted light, which is the reference angle specifying light 100 in this embodiment, toward the light receiving means 7 (second light receiving section 72 described later) without diffraction. Note that the opening 61 need only be able to irradiate the reference angle-specific light 100 toward the second light receiving portion 72, and need not be arranged substantially in the center, nor be formed in a substantially rectangular shape. good too. Moreover, in order to provide a structure corresponding to the opening 61 , the second diffraction grating 6 may be composed of a plurality of diffraction gratings having a plurality of gratings 60 .

The light-receiving means 7 includes a first light-receiving portion 71 for receiving predetermined diffracted light among the plurality of diffracted lights, a second light-receiving portion 72 for receiving diffracted light other than the predetermined diffracted light received by the first light-receiving portion 71, Prepare.
The first diffraction grating 5, the second diffraction grating 6, and the first light receiving portion 71 in the detection means 4 are opposed to the reflection means 3 and separated from the reflection means 3 by a length L in the Z direction (upward direction on the paper surface). placed in position. The second light receiving portion 72 faces the reflecting means 3 and is arranged above the opening 61 of the second diffraction grating 6 (in the upward direction on the paper surface). Further, the second light receiving section 72 is arranged at a position farther from the reflecting means 3 than the first diffraction grating 5 , the second diffraction grating 6 and the first light receiving section 71 .

The first light receiving section 71 includes a plurality of light receiving elements 70 that receive light and convert it into signals. The plurality of light receiving elements 70 are arranged side by side at a predetermined arrangement pitch along the X direction corresponding to the arrangement pitch of the plurality of gratings 50 and 60 . A PDA (Photo Diode Array) is used for the plurality of light receiving elements 70 . A PDA is a photodetector that has the property of being able to measure a plurality of interference fringes at once. Note that the plurality of light receiving elements 70 are not limited to PDAs, and may be arbitrary light receivers such as PSDs (Position Sensitive Detectors) and CCDs (Charge-Coupled Devices).

The first light-receiving part 71 is diffracted as ±1st-order diffracted lights by the first diffraction grating 5, and is diffracted as ±1st-order diffracted lights by the second diffraction grating 6, resulting in two diffracted lights that become the signal diffracted light 111. receive light. Specifically, the first light-receiving unit 71 emits light from the light source 2 via the first diffraction grating 5 , the second diffraction grating 6 , and the reflecting means 3 . Receive the generated interference fringes.

When the parallel light irradiated to the first diffraction grating 5 by the light source 2 passes through the first diffraction grating 5 and is diffracted, it becomes a plurality of diffracted lights and is irradiated to the reflecting means 3, and is reflected by the reflecting means 3. become light. The reflected light is further diffracted by the second diffraction grating 6 into a plurality of diffracted lights. A plurality of diffracted lights diffracted by the second diffraction grating 6 are again irradiated to the reflecting means 3 to become reflected lights, which are irradiated to the light receiving means 7 . Reflected light through the first diffraction grating 5, the second diffraction grating 6, and the reflecting means 3 interferes in the light receiving means 7, so that it corresponds to the arrangement pitch of the plurality of gratings 50 and 60 along the X direction. Generates interference fringes that alternate between light and dark at regular intervals.

In the optical angle sensor 1, the parallel light emitted from the light source 2 changes the direction of the reflected light toward the second diffraction grating 6 when the tilt angle of the reflecting means 3 changes. Therefore, for the parallel light emitted from the light source 2 , the reaching points of the light on the second diffraction grating 6 and the light receiving means 7 change due to the rotation of the reflecting means 3 . As a result, the optical distance (optical path) from the first diffraction grating 5 to the light receiving means 7 changes, so that the interference fringes on the light receiving surface of the light receiving means 7 are displaced. The optical angle sensor 1 detects the change in the tilt angle of the reflecting means 3 from the displacement, which is the movement of the interference fringes.

The second light receiving section 72 receives the reference angle specific light 100 which is diffracted light other than the signal diffracted light 111 which is the two diffracted lights received by the first light receiving section 71 . The second light receiving section 72 is composed of PSD in order to specify the reference angle in the reflecting means 3 . Note that the second light receiving unit 72 is not limited to the PSD, and any light receiver such as a CCD, PDA, CMOS, or the like may be used.
Specifically, the second light receiving section 72 receives the light that has become 0th-order diffracted light from the first diffraction grating 5 and has been reflected by the reflecting means 3 .
In FIG. 1 , for convenience of explanation, ±first-order diffracted light that is the signal diffracted light 111 received by the first light receiving section 71, zero-order diffracted light that is the reference angle specific light 100 that is received by the second light receiving section 72, The arrow indicates the optical path.

FIG. 2 is a block diagram showing the optical angle sensor.
The optical angle sensor 1 further comprises, as shown in FIG. , and an angle calculator 83 .

The signal detection section 81 detects a signal for calculating the tilt angle of the reflection means 3 based on the light received from the first light receiving section 71 .
The specifying unit 82 specifies a reference angle that serves as a reference when calculating the angle based on the light received from the second light receiving unit 72 . The specifying unit 82 stores in advance a reference angle specifying value for specifying the reference angle.
The angle calculation unit 83 calculates the absolute value of the angle based on the signal for calculating the angle detected by the signal detection unit 81 and the reference angle specified by the specification unit 82 .

The optical angle sensor 1 identifies the reference angle as follows.
First, when the measuring instrument provided with the optical angle sensor 1 is powered on, it performs an operation of tilting the reflecting means 3 (see FIG. 1). At this time, the measuring device tilts the reflecting means 3 with a full stroke. The optical angle sensor 1 irradiates parallel light from the light source 2 for identifying the reference angle while tilting the reflecting means 3 by the measuring device. As a result, the first light receiving portion 71 and the second light receiving portion 72 are irradiated with light according to the inclination of the reflecting means 3 .

Next, the first light receiving section 71 receives the ±first order diffracted light, which is the signal diffracted light 111, and the signal detecting section 81 analyzes the interference fringes generated by the signal diffracted light 111 to determine the tilt angle of the reflecting means 3. Detect the signal for the calculation.
Subsequently, the identifying unit 82 collates the position of the light irradiated onto the light receiving surface of the second light receiving unit 72 with the stored reference angle specific value. At this time, the second light receiving section 72 receives the light at the position where the reference angle-specifying light 100 is irradiated and the position where the amount of light on the light receiving surface of the second light receiving section 72 is the largest as the center of gravity position. The specifying unit 82 collates this center-of-gravity position with the reference angle specifying value. When the center-of-gravity position, which is the position irradiated with the reference angle specifying light 100, matches the reference angle specifying value, the specifying unit 82 specifies the position as the reference angle. Then, the angle calculator 83 calculates the absolute value of the displacement of the tilt angle of the reflecting means 3 by combining the signal for calculating the angle analyzed from the interference fringes and the reference angle.

According to this embodiment, the following functions and effects can be obtained.
(1) The calculating means 8 detects a signal for calculating an angle by the signal detecting portion 81 based on the light received from the first light receiving portion 71, and the specifying portion 82 based on the light received from the second light receiving portion 72. , and the absolute value of the angle is determined by the angle calculator 83 based on the signal detected by the signal detector 81 and the reference angle specified by the specifier 82. Since the value is calculated, the reference angle can be specified and the angular displacement of the object to be measured can be detected with high accuracy without using a scale. Therefore, the optical angle sensor 1 can detect angles with high resolution, can detect angles in a wide range, does not have a scale, and can specify a reference angle.

(2) The detector 4 includes a plurality of diffraction gratings 5 and 6 that diffract the light emitted from the light source 2 into a plurality of diffracted beams. and the second light receiving section 72 for receiving the reference angle specific light 100 (zero-order diffracted light) other than the signal diffracted light 111 received by the first light receiving section 71. A signal for calculating an angle can be detected by the light source 2, and a reference angle can be specified as a reference when calculating the angle. Therefore, the optical angle sensor 1 can achieve cost reduction and space saving. In addition, by using one light source 2, there is no error factor due to temperature characteristics and light amount characteristics that occur when a plurality of light sources are provided. Optical properties can be made uniform.

(3) Since the signal detection unit 81 can detect the angle based on two diffracted beams, the accuracy is higher than when detecting the angle based on one diffracted beam or a plurality of diffracted beams. , the absolute value of the angle can be calculated.
(4) Reflecting means 3 is installed on the object to be measured and rotates as the object to be measured rotates. The optical angle sensor 1 can identify the reference angle more reliably.
(5) The specifying unit 82 compares the position of the light irradiated onto the light receiving surface of the second light receiving unit 72 with a reference angle specifying value for specifying the reference angle stored in the specifying unit 82 in advance. In order to specify the reference angle, the reference angle can be specified based on the light with which the second light receiving section 72 is irradiated.

[Second embodiment]
A second embodiment of the present invention will be described below with reference to FIGS. 3 and 4. FIG. In the following description, the same reference numerals are given to the parts that have already been described, and the description thereof will be omitted.

FIG. 3 is a perspective view showing an optical angle sensor according to the second embodiment. Also, FIG. 4 is a block diagram showing the optical angle sensor.
In the first embodiment, the reflecting means 3 has the reflecting surface 30 . In this embodiment, as shown in FIGS. 3 and 4, the reflecting means 3A in the optical angle sensor 1A includes a reflecting portion 31 that reflects light, a diffraction grating portion 32 that diffracts light into a plurality of diffracted beams, It is different from the first embodiment in that it has

The reflecting portion 31 is a mirror that reflects the light emitted from the light source 2, like the reflecting surface 30 of the reflecting means 3 in the first embodiment. It should be noted that the reflecting section 31 does not have to be a mirror and may be of any type as long as it can reflect light.
As shown in FIG. 3, the diffraction grating section 32 is a reflective diffraction grating, and has a plurality of gratings 300 arranged side by side along the direction (Y direction) parallel to the measurement axis. As a result, the ±first-order diffracted lights diffracted by the second diffraction grating 6 are diffracted into a plurality of diffracted lights by the diffraction grating section 32 .

Specifically, the plurality of diffracted lights are Y-direction ±1st-order diffracted lights diffracted from ±1st-order diffracted lights. Of these, the Y direction +1st order diffracted light diffracted by the diffraction grating section 32 is received by the first light receiving section 71 as the signal diffracted light 111A, and the Y direction -1st order diffracted light is received by the second light receiving section as the reference angle specific light 100A. Received at 72 . The reference angle-specific light 100A diffracted by the diffraction grating section 32 is diffracted so as to converge toward the second light receiving section 72 . At this time, since the Y direction −1st order diffracted light of the ±1st order diffracted lights is irradiated as the reference angle specifying light 100A, interference fringes are generated on the light receiving surface of the second light receiving section 72 by the two diffracted lights. However, also in the present embodiment, the second light receiving section 72 receives the position where the reference angle-specifying light 100A is irradiated and the position where the amount of light is the largest in the interference fringes as the barycentric position.

Further, the second light receiving portion 72 is arranged at a position where the light reflected by the reflecting means 3A converges. That is, the second light receiving section 72 is arranged at a position where it can receive the reference angle specific light 100A converged and diffracted by the diffraction grating section 32 . In addition, since the first light receiving portion 71 and the second light receiving portion 72 receive the diffracted light diffracted by the diffraction grating portion 32, they can be arranged at positions close to each other. Therefore, since the optical angle sensor 1A does not need to include a plurality of second light receiving portions, space can be saved.

Then, as shown in FIG. 4, as in the first embodiment, a signal for calculating an angle is detected by the signal detecting section 81 based on the signal diffracted light 111A received by the first light receiving section 71. The reference angle can be specified by the specifying unit 82 based on the reference angle specifying light 100A received by the second light receiving unit 72 . Then, the angle calculator 83 can calculate the absolute value of the tilt angle of the reflecting means 3A by combining the signal from the signal diffracted light 111A and the reference angle.
In FIG. 3, the area of the reflecting section 31 and the area of the diffraction grating section 32 in the reflecting means 3A are arranged so as to have the same area, but the reflecting section can reflect light and the diffraction grating The parts may be arranged on the reflecting surface of the reflecting means in any way as long as they can diffract the light into a plurality of diffracted beams.

In addition to the same effects and effects as (1) to (5) in the first embodiment, the present embodiment can also achieve the following effects.
(6) The reflecting means 3A includes a reflecting portion 31 that reflects light and a diffraction grating portion 32 that diffracts light into a plurality of diffracted beams, so that the first light receiving portion 71 or the second light receiving portion 72 receives light. You can adjust the light you want. Therefore, since the optical angle sensor 1A can adjust the light according to the arrangement of the first light receiving section 71 and the second light receiving section 72, the degree of freedom in design can be improved.

(7) The diffraction grating section 32 in the reflecting means 3A has a plurality of gratings 300 arranged in parallel along the direction parallel to the measurement axis, so that the light received by the first light receiving section 71 or the second light receiving section 72 can be converged in a given direction. Therefore, the optical angle sensor 1A can converge light in accordance with the arrangement of the first light receiving section 71 and the second light receiving section 72, thereby improving the degree of freedom in design.

(8) Since the second light receiving section 72 is arranged at a position where the light reflected by the reflecting means 3A converges, the identifying section 82 identifies the reference angle without having a plurality of second light receiving sections 72. can receive light for Therefore, the optical angle sensor 1</b>A can be designed more easily than the case of having a plurality of second light receiving sections 72 .
(9) Since the optical angle sensor 1A does not need to have a plurality of second light receiving sections 72, space saving and cost reduction can be achieved compared to the case of having a plurality of second light receiving sections.

[Third embodiment]
A third embodiment of the present invention will be described below with reference to FIGS. 5 and 6. FIG. In the following description, the same reference numerals are given to the parts that have already been described, and the description thereof will be omitted.

FIG. 5 is a perspective view showing an optical angle sensor according to the third embodiment. Also, FIG. 6 is a block diagram showing the optical angle sensor.
In the second embodiment, the diffraction grating section 32 had a plurality of gratings 300 arranged side by side along the direction parallel to the measurement axis. In this embodiment, as shown in FIGS. 5 and 6, the diffraction grating portion 32B of the reflecting means 3B in the optical angle sensor 1B is arranged along the direction (X direction) orthogonal to the measurement axis on the reflecting surface of the reflecting means 3B. It differs from the second embodiment in that it has a plurality of gratings 311 arranged side by side.

Further, in each of the above-described embodiments, only one second light-receiving portion 72 in the light-receiving means 7 was provided in the detecting means 4 . In this embodiment, the light receiving unit 7B further includes a third light receiving unit 73 that functions in the same manner as the second light receiving unit 72 and receives the reference angle specific light that is diffracted light other than the ±1st order diffracted light. It differs from each of the above-described embodiments in that two second light receiving portions for receiving the reference angle specific light are provided inside.

The diffraction grating section 32B diffracts the ±first-order diffracted lights diffracted by the second diffraction grating 6 into a plurality of diffracted lights. Specifically, the plurality of diffracted beams are X-direction 0th-order diffracted beams diffracted from ±1st-order diffracted beams, X-direction ±1st-order diffracted beams, and the like. Among them, the signal diffracted light 111B, which is the X-direction +1st-order diffracted light diffracted by the diffraction grating section 32B, is received by the first light receiving section 71, and the reference angle specific light 100B, which is the X-direction 0th-order diffracted light, diverges. , and received by the second light receiving section 72 and the third light receiving section 73 .
The second light-receiving portion 72 and the third light-receiving portion 73 are arranged at positions where they can receive the reference angle-specifying light 100B diffracted so as to diverge at the diffraction grating portion 32B. Accordingly, even if a plurality of reference angle specifying lights 100B are generated, the optical angle sensor 1B can receive diffracted lights necessary for specifying the reference angle from a plurality of positions.

Further, in each of the above-described embodiments, the specifying unit 82 in the computing unit 8 specifies the reference angle based on the light received from the single second light receiving unit 72 . In this embodiment, as shown in FIG. 6, the specifying unit 82B in the computing unit 8B specifies the reference angle based on the reference angle specifying light 100B received by the second light receiving unit 72 and the third light receiving unit 73. is different from each of the above embodiments. With such a configuration, the specifying unit 8B can specify the reference angle even if a plurality of reference angle specifying lights 100B are generated.

Furthermore, in the case where the reference angle is specified based on one reference angle specifying light 100B and the case where the reference angle is specified based on the plurality of reference angle specifying lights 100B, the reference angle is specified based on the plurality of reference angle specifying lights 100B. By doing so, the reference angles specified based on the light received by the second light receiving section 72 and the third light receiving section 73 can be compared with each other, and the presence or absence of errors can be confirmed. Therefore, the optical angle sensor 1B can specify a reference angle with little error even if noise occurs. In FIG. 5, the region of the reflecting portion 31 and the region of the diffraction grating portion 32B in the reflecting means 3B are arranged so as to have the same area, but the reflecting portion can reflect light and the diffraction grating The parts may be arranged on the reflecting surface of the reflecting means in any way as long as they can diffract the light into a plurality of diffracted beams.

In addition to the same actions and effects as (1) to (6) in the above-described embodiment, the following actions and effects can also be obtained in this embodiment.
(10) The diffraction grating section 32B in the reflecting means 3B has a plurality of gratings 311 arranged side by side along the direction orthogonal to the measurement axis on the reflecting surface of the reflecting means 3B, so that the first light receiving section 71 and the second The light received by the light receiving section 72 and the third light receiving section 73 can be diverged in a predetermined direction. Therefore, the optical angle sensor 1B can diverge light according to the arrangement of the first light receiving section 71, the second light receiving section 72, and the third light receiving section 73, and can improve the degree of freedom in design.

[Fourth embodiment]
A fourth embodiment of the present invention will be described below with reference to FIGS. 7 and 8. FIG. In the following description, the same reference numerals are given to the parts that have already been described, and the description thereof will be omitted.

FIG. 7 is a perspective view showing an optical angle sensor according to a fourth embodiment. FIG. 8 is a block diagram showing the optical angle sensor.
In this embodiment, the optical angle sensor 1C includes a half mirror 10 unlike the first embodiment. Therefore, the first light receiving portion 71 and the second light receiving portion 72 receive light through the half mirror 10 .
Further, in the first embodiment, the first diffraction grating 5 of the optical angle sensor 1 was a transmission type diffraction grating. The first diffraction grating 5C of the optical angle sensor 1C in this embodiment differs from that in the first embodiment in that it is a reflective diffraction grating.

In this embodiment, the light source 2 irradiates parallel light toward the half mirror 10, as shown in FIG. The light applied to the half mirror 10 is split into reflected light reflected by one surface of the half mirror 10 facing the light source 2 and transmitted light traveling through the half mirror 10 .
The reflected light reflected by the half mirror 10 is diffracted into a plurality of diffracted lights by the first diffraction grating 5C. In FIG. 7, for convenience of explanation, the signal diffracted light 111C which is the ±1st order diffracted light received by the first light receiving unit 71 and the light other than the ±1st order diffracted light received by the second light receiving unit 72 (0th order diffracted light) The arrows indicate the optical paths of the reference angle specific light 100C.

Of the plurality of diffracted beams diffracted by the first diffraction grating 5C, ±1st-order diffracted beams are reflected by the reflecting surface 30 of the reflecting means 3 and further diffracted by the second diffraction grating 6 into a plurality of diffracted beams. be. Of the plurality of diffracted lights diffracted by the second diffraction grating 6, the signal diffracted light 111C, which is ±1st order diffracted light, is reflected by the reflecting surface 30 of the reflecting means 3 and received by the first light receiving section 71. be.

The transmitted light that is split by the half mirror 10 and travels through the half mirror 10 is reflected by the reflecting surface of the reflecting means 3 and received by the second light receiving section 72 . That is, the second light receiving section 72 receives the light reflected by the reflecting means 3 as the reference angle specific light 100C.
Then, as shown in FIG. 8, similarly to the first embodiment, the signal detection unit 81 detects a signal for calculating an angle based on the signal diffracted light 111C received by the first light receiving unit 71, and specifies the angle. The part 82 specifies the reference angle based on the reflected light (reference angle specifying light 100C) transmitted through the half mirror 10 , reflected by the reflecting means 3 , and received by the second light receiving part 72 . The angle calculator 83 can calculate the absolute value of the tilt angle of the reflecting means 3 by combining the signal based on the signal diffracted light 111C and the reference angle.

In addition to the same effects and effects as (1) to (5) in the first embodiment, the present embodiment can also achieve the following effects.
(11) The half mirror 10 splits the light emitted from the light source 2 into two lights. As a result, one light is received by the first light receiving portion 71 and used for signal detection by the signal detecting portion 81 for calculating the angle, and the other light is received by the second light receiving portion and is used as a reference by the specifying portion 82 . Angle can be specified. Therefore, the optical angle sensor 1C can improve the degree of freedom in design.
(12) Since the light emitted from the light source 2 is split into two by the half mirror 10, the optical angle sensor 1C uses one light source 2 to calculate the angle without providing a plurality of light sources 2. A signal can be detected and a reference angle can be identified.

[Modification of Embodiment]
It should be noted that the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.
For example, in each of the above-described embodiments, the optical angle sensors 1, 1A to 1C were provided in the measuring device, but they may be provided in something other than the measuring device, and may be provided in any device. is not particularly limited.

The optical angle sensors 1, 1A to 1B of the first to third embodiments do not have the half mirror 10, but the optical angle sensors 1, 1A to 1B have the half mirror 10. It may be a configuration.

In each of the above-described embodiments, the predetermined diffracted light received by the first light receiving unit 71 is ±first-order diffracted light and is based on two diffracted lights. Instead, two or more diffracted beams may be received, one diffracted beam may be received, and the ±1st order diffracted beams may not be received.
In short, the first light receiving section may receive any diffracted light as long as the signal detecting section can detect a signal for calculating the angle based on the light received from the first light receiving section.
In each embodiment, the first light receiving section receives ±1st order diffracted light and the second light receiving section receives 0th order diffracted light. The second light receiving section may receive any light as long as it receives diffracted light other than the predetermined diffracted light received by the first light receiving section.

In the first to third embodiments, the second light receiving section 72 receives the light reflected by the reflecting means 3, 3A to 3B. The light split by the half mirror 10 may be received without using the reflecting means as in the embodiment. In short, as long as the specifying unit can specify the reference angle based on the light received from the second light receiving unit, the second light receiving unit may receive light through any optical path.

In the second embodiment, the diffraction grating section 32 has a plurality of gratings 300 arranged in parallel along the direction parallel to the measurement axis. has a plurality of gratings 311 arranged side by side along the direction orthogonal to the measurement axis on the reflecting surface of , but the reflecting means, like the first embodiment and the fourth embodiment, has a diffraction grating section. You don't have to.

In the second embodiment, the second light receiving section 72 is arranged at a position where the light reflected by the reflecting means 3 converges. It may be arranged at any position as long as it can receive diffracted light other than light.
In the third embodiment, the light receiving means 7B has the third light receiving section 73 which functions in the same manner as the second light receiving section 72 and receives diffracted light other than the predetermined diffracted light received by the first light receiving section 71. However, the optical angle sensor may further include a light receiving section having the same function as the second light receiving section. The number of the second light receiving portions is arbitrary as long as the diffracted light other than the predetermined diffracted light received by the first light receiving portions can be received.

Although the first diffraction gratings 5 and 5C and the second diffraction grating 6 are provided as the plurality of diffraction gratings in each of the above-described embodiments, the plurality of diffraction gratings may include a third diffraction grating. and may have more diffraction gratings. In short, the optical angle sensor only needs to have a plurality of diffraction gratings.

In each of the above-described embodiments, the specifying units 82 and 82B store a reference angle specifying value for specifying the reference angle, and determine the position of the light irradiated on the light receiving surface of the second light receiving unit 72 (third light receiving unit 73). and a stored reference angle specific value. The reference angle may be specified by any method as long as it can be specified.

INDUSTRIAL APPLICABILITY As described above, the present invention can be suitably used for optical angle sensors.

1, 1A-1C optical angle sensor 2 light source 3, 3A-3B reflection means 4, 4B detection means 5, 5C first diffraction grating (plurality of diffraction gratings)
6 second diffraction grating (multiple diffraction gratings)
7, 7B light-receiving means 71 first light-receiving part 72 second light-receiving parts 8, 8B computing means 81 signal detecting parts 82, 82B specifying part 83 angle calculating part 10 half mirror

Claims (9)

a light source that emits light, a reflecting means that rotates about a predetermined axis as a measurement axis and reflects the light emitted from the light source, a detecting means that detects the light emitted from the light source, and the detecting means. an optical angle sensor comprising a computing means for computing an angle based on the detected signal,
The detection means is
a plurality of diffraction gratings for diffracting the light into a plurality of diffracted lights;
and a light receiving means for receiving light emitted from the light source,
The light receiving means is
a first light receiving unit that receives predetermined diffracted light among the plurality of diffracted lights;
a second light receiving unit that receives diffracted light other than the predetermined diffracted light received by the first light receiving unit;
The computing means is
a signal detection unit that detects a signal for calculating an angle based on the light received from the first light receiving unit;
a specifying unit that specifies a reference angle that serves as a reference when calculating an angle based on the light received from the second light receiving unit;
an angle calculation unit that calculates an absolute value of an angle based on the signal detected by the signal detection unit and the reference angle specified by the specification unit ;
The reflecting means is
Relative to the light source and the detection means, which is attached to a rotating measurement object, has a reflecting surface without a diffraction grating for diffracting the light into a plurality of diffracted beams, and is fixed at a predetermined position. an optical angle sensor that rotates according to the rotation of the object to be measured . The optical angle sensor of claim 1, wherein
The optical angle sensor, wherein the predetermined diffracted light beams received by the first light receiving unit are two diffracted light beams. In the optical angle sensor according to claim 1 or claim 2,
The second light receiving section is
An optical angle sensor that receives light reflected by the reflecting means. In the optical angle sensor according to any one of claims 1 to 3,
The first light receiving section and the second light receiving section are
An optical angle sensor that receives light through a half mirror. In the optical angle sensor according to any one of claims 1 to 4,
The reflecting means is
An optical angle sensor, comprising: a reflecting portion that reflects light; and a diffraction grating portion that diffracts light into a plurality of diffracted beams. An optical angle sensor according to claim 5, wherein
The diffraction grating section
An optical angle sensor comprising a plurality of gratings arranged side by side along a direction parallel to the measurement axis. An optical angle sensor according to claim 5, wherein
The diffraction grating section
An optical angle sensor comprising a plurality of gratings arranged side by side along a direction orthogonal to the measuring axis on the reflecting surface of the reflecting means. In the optical angle sensor according to any one of claims 1 to 6,
The second light receiving section is
An optical angle sensor, wherein the optical angle sensor is arranged at a position where the light reflected by the reflecting means converges. In the optical angle sensor according to any one of claims 1 to 8,
The identification unit
A reference angle specific value for specifying the reference angle is stored, and the reference angle is specified by comparing the position of the light irradiated onto the light receiving surface of the second light receiving unit and the reference angle specific value. An optical angle sensor characterized by:

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