Distance measuring sensor

Abstract

[Abstract] This distance measuring sensor includes at least one first optical element that performs one of a light emitting operation and a light receiving operation, and a plurality of second optical elements that perform the other operation. A control unit controls the light receiving and emitting operations of the first optical element and the plurality of second optical elements. The plurality of second optical elements are arranged along an imaginary first straight line that passes through the first optical element, and the first optical element has directivity in the direction of a distance measurement axis orthogonal to the first straight line. Each of the plurality of second optical elements has a directivity that is wider than the directivity of the first optical element, the directivity being inclined toward the distance measurement axis. The control unit operates the first optical element and the plurality of second optical elements, and acquires measured light reception levels due to each of the plurality of second optical elements as light reception level measurement values due to the second optical elements. The distribution of the light reception level measurement values is obtained from the light reception level measurement values due to each of the plurality of second optical elements and the position of each of the plurality of second optical elements, and a measurement value of the distance to an object is obtained from the distribution of the light reception level measurement values.

Description

Distance measuring sensor

[0001] The present invention relates to a distance measuring sensor.

[0002] For industrial robots, service robots, and other such robots, collision avoidance is extremely important from a safety perspective. To avoid collisions, it is preferable to use a distance sensor capable of measuring the absolute distance to an obstacle. Service robots, in particular, are expected to operate normally in a variety of environments. For example, they are expected to be robust enough to operate normally under strong ambient light or in an environment where multiple systems coexist. Furthermore, they are also expected to operate normally even if some of their components are faulty or dirty.

[0003] A distance measuring sensor is known that measures the distance to an object using the principle of triangulation by arranging multiple light-emitting elements and light-receiving elements in a straight line (Patent Document 1). In this distance measuring sensor, one light-emitting element emits light, which is scattered by the object, and the light-receiving element that receives the light most strongly is selected as a hot spot, and the distance to the object is calculated from the distance between the emitting light-emitting element and the selected light-receiving element.

[0004] U.S. Patent No. 9,164,625

[0005] A common method for separating measurement light emitted from a light-emitting element from external light is to modulate the light emitted from the light-emitting element. However, when strong external light is present, the light-receiving element may become saturated and unable to recognize the modulated light. To reduce the effects of external light, it is effective to narrow the directionality of the light-receiving element toward the object. This is because the object blocks the external light, reducing the probability that the external light will enter the light-receiving element.

[0006] In the distance measuring sensor described in Patent Document 1, two lenses are associated with each of a plurality of light receiving elements, and light coming from two directions is incident on one light receiving element. Because light coming from two directions is incident on the light receiving element, the light receiving element becomes susceptible to the influence of external light.

[0007] In addition, modulated light from another distance measuring sensor may also be incident on the light receiving element. If the modulation timing happens to be the same, it becomes impossible to distinguish whether the light incident on the light receiving element is modulated light from the sensor itself or from another sensor, making it impossible to measure the distance accurately.

[0008] Furthermore, if one of the light receiving elements malfunctions, the light receiving element becomes a hot spot and the distance cannot be measured accurately.

[0009] An object of the present invention is to provide a distance measuring sensor that is less susceptible to the effects of extraneous light or malfunction of one optical element.

[0010] According to one aspect of the present invention, there is provided a light receiving device comprising: at least one first optical element performing one of an emitting operation and a receiving operation, and a plurality of second optical elements performing the other operation; and a control unit that controls the emitting and receiving operations of the first optical element and the plurality of second optical elements, wherein the plurality of second optical elements are arranged along an imaginary first straight line that passes through the first optical element, the first optical element has directivity in the direction of a ranging axis that is perpendicular to the first straight line, and each of the plurality of second optical elements has directivity that is wider than the directivity of the first optical element, the first optical element and the plurality of second optical elements are arranged such that a portion of light emitted from one of the first optical element and the second optical elements and scattered by an object enters the other optical element, and each of the plurality of second optical elements has directivity that is inclined toward the ranging axis, and the control unit operates the first optical element and the plurality of second optical elements to obtain a light receiving level measured due to each of the plurality of second optical elements as a light receiving level measurement value due to the second optical element, A distance measuring sensor is provided that determines a distribution of the received light level measurement values ​​from the received light level measurement values ​​attributable to each of the plurality of second light elements and the positions of each of the plurality of second light elements, and determines a measurement value of the distance to the object from the distribution of the received light level measurement values.

[0011] Since the second optical element has directivity inclined in the direction of the ranging axis of the first optical element, it is less susceptible to the influence of external light than when it has directivity in other directions. Furthermore, since the measured value of the distance to the object is determined from the distribution of the measured light reception levels caused by multiple second optical elements, it is possible to determine the distance to the object even if one second optical element is malfunctioning.

[0012] FIG. 1 is a schematic diagram of a distance measuring sensor according to a first embodiment. FIG. 2 is a schematic diagram showing the positional relationship between a first light element, multiple second light elements, a distance measurement axis, and the direction in which the light receiving sensitivity of the second light elements is maximized. FIGS. 3A to 3F are graphs showing an example of theoretically calculated light receiving levels of the second light elements. FIG. 4 is a graph showing the relationship between the weighted average of the theoretically calculated light receiving levels and the distance to the object. FIG. 5 is a block diagram of a control unit of a distance measuring sensor according to a second embodiment. FIG. 6A is a graph showing an example of the distribution of theoretically calculated light receiving levels when highly directional light is incident on multiple second light elements from a distance of 10 m. FIG. 6B is a graph showing an example of the distribution of theoretically calculated light receiving levels when highly directional light is incident on the seventh second light element from a light source located 500 mm away from the first light element. FIG. 7 is a graph comparing the distribution of measured light receiving levels with the distribution of theoretically calculated light receiving levels calculated from measured distances to the object. FIG. 8 is a flowchart of the processing procedure performed by the control unit (FIG. 5) of the distance measuring sensor according to the third embodiment. FIGS. 9A and 9B are graphs showing an example of the distribution of measured light reception levels and the distribution of theoretically calculated light reception levels when the distance to the object is 200 mm, respectively. FIG. 10 is a schematic diagram of a distance measuring sensor according to the fourth embodiment. FIG. 11 is a graph showing an example of the distribution of theoretically calculated light reception levels in the distance measuring sensor according to the fourth embodiment. FIG. 12 is a schematic diagram of a distance measuring sensor according to the fifth embodiment. FIG. 13A is a schematic cross-sectional view of a second optical element used in a distance measuring sensor according to a first modified example of the fifth embodiment, and FIG. 13B is a schematic cross-sectional view of a second optical element used in a distance measuring sensor according to a second modified example of the fifth embodiment. FIG. 14A is a schematic plan view of a second optical element used in a distance measuring sensor according to a third modified example of the fifth embodiment, and FIG. 14B is a cross-sectional view taken along dashed line 14B-14B in FIG. 14A. Fig. 15A is a schematic plan view of a second optical element used in a distance measuring sensor according to a fourth modified example of the fifth embodiment, Fig. 15B is a cross-sectional view taken along dashed line 15B-15B in Fig. 15A, Fig. 16A is a schematic plan view of a second optical element used in a distance measuring sensor according to a fifth modified example of the fifth embodiment, and Fig. 16B is a cross-sectional view taken along dashed line 16B-16B in Fig. 16A.FIG. 17 is a schematic side view of an articulated robot equipped with a distance measuring sensor according to any one of the first to fifth embodiments.

[0013] [First Embodiment] A distance measuring sensor according to a first embodiment will be described with reference to Figures 1 to 4. Figure 1 is a schematic diagram of a distance measuring sensor 20 according to the first embodiment. The distance measuring sensor 20 according to the first embodiment includes one first light element 21 that performs a light emitting operation, multiple second light elements 22 that perform a light receiving operation, and a control unit 50. In Figure 1, the first light element 21 is hatched.

[0014] The first optical element 21 and the plurality of second optical elements 22 are arranged along an imaginary first straight line 40, and all of the second optical elements 22 are arranged on one side as viewed from the first optical element 21. For example, whether or not they are arranged on the first straight line 40 is determined based on the light-emitting region (active region) of the first optical element 21 and the light-receiving region (active region) of the second optical element 22. The plurality of second optical elements 22 are arranged at equal intervals, and the interval between the second optical element 22 closest to the first optical element 21 and the first optical element 21 is ½ of the interval between adjacent second optical elements 22.

[0015] The first optical element 21 has directivity in a direction perpendicular to the first line 40. For example, the direction in which the light emission intensity of the first optical element 21 is maximum is perpendicular to the first line 40. In FIG. 1 , the light emission intensity distribution 31 of the first optical element 21 is indicated by a thin solid line. An xyz Cartesian coordinate system is defined in which the direction parallel to the first line 40 is the x direction and the direction in which the light emission intensity of the first optical element 21 is maximum is the z direction. The direction from the first optical element 21 toward the second optical element 22 is defined as the positive direction of the x axis, and the direction in which light is emitted from the first optical element 21 is defined as the positive direction of the z axis. A half line extending from the first optical element 21 in the positive direction of the z axis is referred to as a ranging axis 23.

[0016] The shape of the distribution 32 of light receiving sensitivity of the multiple second light elements 22 is the same. The directivity (directivity of light receiving sensitivity) of each of the second light elements 22 is wider than the directivity of the first light elements 21. Each of the multiple second light elements 22 has directivity that is inclined from the positive direction of the z axis toward the ranging axis 23. The direction 33 in which the light receiving sensitivity of each of the multiple second light elements 22 is maximized is parallel to the xz plane, and the directions 33 in which the light receiving sensitivity of each of the second light elements 22 is maximized are parallel to each other.

[0017] The distance measurement sensor 20 measures the distance from the first light element 21 to an object 60 located on a distance measurement axis 23. Light emitted from the first light element 21 is scattered by the object 60. A portion of the light scattered by the object 60 is incident on the plurality of second light elements 22.

[0018] The control unit 50 includes an emission control unit 51, a light reception sequencer 52, a calculation unit 53, and an output unit 54. The emission control unit 51 controls the timing of light emission of the first light element 21. The light reception sequencer 52 sequentially acquires measurement values ​​of the light reception level by the plurality of second light elements 22. The measurement value of the light reception level by a specific second light element 22 can be said to be the measurement value of the light reception level caused by that second light element 22.

[0019] The calculation unit 53 controls the light emission control unit 51, and also performs various calculations on the measurement value of the light reception level (hereinafter, sometimes simply referred to as the "measured light reception level") acquired by the light reception sequencer 52, to determine the distance from the first light element 21 to the object 60. Information specifying the determined distance (hereinafter, sometimes referred to as the "measured distance") is output from the output unit 54.

[0020] Next, the calculation performed by the calculation unit 53 will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing the positional relationship between the first optical element 21, the plurality of second optical elements 22, the distance measurement axis 23, and the direction 33 in which the light receiving sensitivity of the second optical element 22 is maximized. The position of the first optical element 21 is indicated by a hollow circle, and the positions of each of the plurality of second optical elements 22 are indicated by a filled circle. The first optical element 21 and the plurality of second optical elements 22 are arranged on a first line 40. The plurality of second optical elements 22 are assigned serial numbers starting from 1 in the positive direction of the x-axis.

[0021] A direction 33 of maximum light sensitivity extending from each of the second light elements 22 is inclined from the positive direction of the z axis toward the distance measurement axis 23. The straight line indicating the direction 33 of maximum light sensitivity intersects with the distance measurement axis 23.

[0022] Next, preferred examples of the arrangement and directivity of the second optical elements 22 will be described. The measurable range is determined based on the required specifications for the distance measuring sensor 10. It is preferable to set the arrangement and directivity of the second optical elements 22 so that at least two second optical elements can receive scattered light from an object 60 at the closest position within the measurable range. Furthermore, it is preferable to set the arrangement and directivity of the second optical elements 22 so that at least three second optical elements 22 can receive scattered light from an object 60 at a position away from the closest position within the measurable range by a distance equivalent to 10% of the measurable range.

[0023] The distance from the first optical element 21 to the closest second optical element 22 is denoted as a. The interval between two adjacent second optical elements 22 is 2a. The intersection of the line indicating the direction 33 in which the light receiving sensitivity of the second second optical element 22 is maximum and the distance measurement axis 23 is denoted as P. ２ The intersection point P ２ The light scattered by the object 60 located at the intersection P is mainly received by the first and second second optical elements 22. ２ The distance to the intersection point P is denoted as b. ２ corresponds to the closest position in the measurable range.

[0024] The intersection of the line indicating the maximum light-receiving sensitivity direction 33 of the third second light element 22 and the distance measurement axis 23 is designated as P. ３ The intersection point P ３ The distance to is (5 / 3)b by proportional calculation.

[0025] Intersection P ２ From intersection point P ３ Under the condition that the distance (2 / 3)b to the intersection point P corresponds to 10% of the measurable range, ２The distance from the first light element 21 to the farthest position in the distance measurement range is (20 / 3)b. The distance from the first light element 21 to the farthest position in the distance measurement range is (23 / 3)b. The intersection P of the distance measurement axis 23 with the line indicating the maximum light-receiving sensitivity direction 33 of the twelfth second light element 22 is １２ The distance to is equal to (23 / 3)b.

[0026] Therefore, if 12 second optical elements 22 are arranged, the distance to the object 60 within the measurable range can be measured. In other words, by measuring the light reception levels of the first through twelfth second optical elements 22, the distance to the object 60 within the measurable range can be measured. Note that the number of second optical elements 22 to be considered is not limited to 12, but is a design matter that should be determined in consideration of the measurable range.

[0027] Next, the light reception level by the second light element 22 will be described. When the object 60 can be regarded as a Lambertian scatterer, scattered light from the object 60 travels in all directions. Let L be the light emission intensity of the first light element 21, α be the reflectance of the object 60, C be the photoelectric conversion efficiency of the second light element 22, r be the distance from the object 60 to the second light element 22, θ be the inclination angle of the direction 33 of maximum light reception sensitivity of the second light element 22 from the positive direction of the z axis, φ be the angle between the normal direction of the object 60 at the light point on the object 60 as seen from the second light element 22 and the direction 33 of maximum light reception sensitivity of the second light element 22, and d be the distance from the first light element 21 to the ith second light element 22. ｉ Then, the light receiving level detected by the second optical element 22 is expressed as S ｉ can be approximately described by the following equation: Here, n is an index representing the width of the directivity of the second optical element 22, and the larger n is, the narrower the directivity. Using equation (1), the theoretical calculation value of the light reception level of each of the multiple second optical elements 22 can be obtained.

[0028] 3A to 3F are graphs showing an example of theoretically calculated values ​​of the light reception level of the second optical element 22. The horizontal axis represents the serial number assigned to the second optical element 22, and the vertical axis represents the theoretically calculated value of the light reception level as a relative value normalized with the maximum value set to 1. The light source of the scattered light from the object 60 was the intersection of the distance measurement axis 23 and the surface of the object 60. The inclination angle θ (FIG. 2) was 30°, the half-width at half maximum of the directivity of the second optical element 22 was 15° (n=20), and the spacing 2a (FIG. 2) between the second optical elements 22 was 30 mm. FIGS. 3A, 3B, 3C, 3D, 3E, and 3F show theoretically calculated values ​​of the light reception level when the distance z to the object 60 is 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, and 300 mm, respectively.

[0029] Because the half-width at half maximum of the directivity of the second optical elements 22 is as wide as 15°, scattered light is detected by the first and second second optical elements 22 even when the distance z to the object 60 is as short as 50 mm. As the distance z to the object 60 increases, more second optical elements 22 detect scattered light. The second optical element 22 at which the theoretically calculated value of the received light level reaches its maximum value becomes farther from the first optical element 21 as the distance z to the object 60 increases. As shown in FIGS. 3A to 3F , as the distance z to the object 60 changes, the distribution of the theoretically calculated values ​​of the received light level changes. This means that the distance z to the object 60 can be estimated by knowing the distribution of the measured values ​​of the received light level.

[0030] 3A to 3F, the theoretically calculated values ​​of the light receiving levels of the second optical elements 22 are weighted by an index representing the distance from the first optical element 21 to the second optical element 22, and the weighted average value can be calculated by averaging them. As the index representing the distance, the serial number assigned to the second optical element 22 may be used, or the distance itself may be used.

[0031] 4 is a graph showing the relationship between the weighted average value of the theoretically calculated values ​​of the received light levels and the distance z to the object 60. The horizontal axis represents the weighted average value of the theoretically calculated values ​​of the received light levels, and the vertical axis represents the distance to the object in units of mm. Note that the serial number assigned to the second light element 22 is used as an index representing the distance from the first light element 21 to the second light element 22. Once the weighted average value of the measured values ​​of the received light levels is determined, the distance z to the object 60 (measured value of distance z) can be determined using the graph shown in FIG.

[0032] 3A to 3F show an example in which the distance to the object 60 is 300 mm or less, but even if the distance to the object 60 is longer than 300 m, distance measurement is possible as described below.

[0033] When the distance to the object 60 is greater than 300 mm, scattered light from the object 60 is distributed in a range outside the 16th second optical element 22. In a configuration with 16 second optical elements 22, the intensity of scattered light distributed in a range outside the 16th second optical element 22 cannot be measured. However, as the distance to the object 60 increases, the position where the peak of the received light level appears shifts to the second optical element 22 with a larger serial number. As a result, the weighted average value increases. That is, as the distance to the object 60 increases within a certain range, the weighted average value monotonically increases. Therefore, the distance to the object 60 can be calculated from the weighted average value. In this way, distance measurement is possible even if part of the distribution of the received light level extends beyond the position of the outermost second optical element 22.

[0034] Next, a description will be given of the advantageous effects of Example 1. In Example 1, the distance to the object is calculated based on the light reception level measurement values ​​measured by a plurality of second optical elements 22, and therefore, more reliable measurements can be performed than when the distance is calculated based on the light reception level measurement value measured by a single second optical element 22.

[0035] For example, in the first embodiment, a weighted average value of the light reception level measurements by the multiple second optical elements 22 is calculated, and the distance is calculated from the calculated weighted average value. By calculating the weighted average value, the calculated distance is less likely to be affected by a specific one of the second optical elements 22. Therefore, even if one of the multiple second optical elements 22 malfunctions, the distance can be estimated based on the weighted average value of the light reception level measurements by the other second optical elements 22 that are operating normally.

[0036] For example, when a weighted average is calculated for the theoretically calculated light reception levels of the second optical elements 22 when the distance to the object is 200 mm, the weighted average value is 4.24. Consider a case where the fifth second optical element 22 has failed and is not working. When calculating the weighted average of the theoretically calculated light reception levels of the second optical elements 22, if the theoretically calculated light reception level of the fifth second optical element 22 is set to zero and the weighted average is calculated, the weighted average value becomes 3.81. When the weighted average value is 3.81, the distance to the object is approximately 171 mm.

[0037] In this way, even if one second optical element 22 fails, the distance to the target object can be calculated with an error of at most 15%. This allows for a highly stable distance measuring sensor to be realized without becoming unable to measure due to contamination or failure of some of the second optical elements 22. Note that when using a semiconductor element with an inherent weighted average effect, such as a position sensitive detector, a failure of the position sensitive detector itself will render distance measurement impossible. By using multiple separate second optical elements 22 with light receiving functions, as in the first embodiment, distance measurement can be continued with a small measurement error even if one light receiving element malfunctions.

[0038] 1, in the first embodiment, each of the multiple second optical elements 22 has directivity inclined toward the object 60 on the ranging axis 23. The second optical elements 22 have relatively low light sensitivity to external light arriving from a direction in which the object 60 does not exist. Therefore, the influence of external light is reduced compared to when the direction in which the second optical elements 22 have maximum light sensitivity is parallel to the ranging axis 23 (FIG. 1) or when the direction in which the second optical elements 22 have maximum light sensitivity appears in two directions.

[0039] If the directivity of the second optical elements 22 is too broad, the second optical elements 22 will be susceptible to external light. In order to enhance the excellent effect of being less susceptible to external light, it is preferable to set the half width at half maximum of the directivity of each of the second optical elements 22 to 20° or less.

[0040] Conversely, if the half width at half maximum of the directivity of each of the second optical elements 22 is too narrow, the number of second optical elements 22 that receive scattered light from the object 60 (FIG. 1) will be reduced. As an example, as described with reference to FIG. 2, the closest position in the distance measurement range (the intersection point P ２ ), it is preferable that the first and second second optical elements 22 have directivity to such an extent that scattered light from the object 60 can be detected by the first and second second optical elements 22. In addition, it is preferable that the first and second second optical elements 22 have directivity to such an extent that scattered light from the object 60 can be detected by the first and second second optical elements 22 from the closest position in the measurable range by a distance equivalent to 10% of the measurable range (the intersection P ３ ), it is preferable that the second light element 22 has a degree of directivity such that scattered light from the object 60 can be detected by the first, second, and third second light elements 22.

[0041] Next, the preferred directivity of the first optical element 21 will be described. As the directivity of the first optical element 21 ( FIG. 1 ) increases, the incidence area of ​​the measurement light on the surface of the object 60 increases. Equation (1) is derived under the condition that the incidence area of ​​the measurement light on the surface of the object 60 is a point. Therefore, as the incidence area of ​​the measurement light increases, the error in measuring the distance increases. To improve measurement accuracy, it is preferable to narrow the directivity of the first optical element 21. For example, it is preferable to set the half width at half maximum of the emission intensity to 5° or less.

[0042] Next, a distance measuring sensor according to a modification of the first embodiment will be described. In the first embodiment, the first light element 21 ( FIG. 1 ) has a light-emitting function and the multiple second light elements 22 ( FIG. 1 ) have a light-receiving function. However, the opposite may be true: the first light element 21 has a light-receiving function and the multiple second light elements 22 have a light-emitting function. In this case, the multiple second light elements 22 are operated one by one in sequence, and scattered light from the target is detected by the first light element 21. The measured value of the received light level measured by the first light element 21 can be considered to be the measured value of the received light level caused by the second light element 22 that emitted light during measurement. By correlating the measured value of the received light level with the position of the second light element 22 that emitted light when the received light level was measured by the first light element 21, a distribution of the measured values ​​of the received light level can be obtained.

[0043] In the first embodiment, an example was shown in which the plurality of second optical elements 22 were arranged at equal intervals, but the plurality of second optical elements 22 do not necessarily have to be arranged at equal intervals. For example, even if the plurality of second optical elements 22 are not arranged at equal intervals, the actual distance d from the first optical element 21 to the ith second optical element 22 can be calculated. ｉ is known, the light receiving level S of the i-th second optical element 22 can be calculated from equation (1). ｉ The theoretical calculated value can be obtained.

[0044] Second Embodiment Next, a distance measuring sensor according to a second embodiment will be described with reference to Figures 5 to 7. Below, a description of the configuration common to the distance measuring sensor according to the first embodiment described with reference to Figures 1 to 4 will be omitted.

[0045] 5 is a block diagram of a control unit 50 of a distance measuring sensor according to the second embodiment. The control unit 50 of the distance measuring sensor 20 (FIG. 1) according to the first embodiment includes a light emission control unit 51, a light reception sequencer 52, a calculation unit 53, and an output unit 54, but the control unit 50 of the distance measuring sensor according to the second embodiment further includes a determination unit 55 and a theoretically calculated light reception level value calculation unit 56.

[0046] The theoretically calculated light-receiving level calculation unit 56 calculates theoretically calculated light-receiving level values ​​for the plurality of second light elements 22 using, for example, equation (1), from the measured values ​​of the distance to the object calculated by the calculation unit 53. The determination unit 55 compares the distribution of the calculated theoretically calculated light-receiving level values ​​with the distribution of the measured light-receiving level values, and determines the significance of the measured values ​​of the distance to the object calculated by the calculation unit 53 based on the comparison result.

[0047] 6A and 6B, an example of a technique for determining the significance of a distance measurement to an object will be described.

[0048] 6A is a graph showing an example of the distribution of theoretically calculated values ​​of received light levels when highly directional light is incident on multiple second light elements 22 from a distance of 10 m. In fact, when highly directional light is incident on multiple second light elements 22 from a distance of 10 m, a distribution of measured received light levels similar to the distribution shown in FIG. 6A is obtained. The measured value of the distance to the object can be calculated from the weighted average value of the received light levels obtained from the graph of the distribution of measured received light levels and the graph shown in FIG. 4. When the distribution of theoretically calculated values ​​of received light levels is obtained from the measured value of the distance to the object, the distribution shown in FIGS. 3A to 3F is obtained.

[0049] It can be seen that the distribution of the measured light-receiving level values, which is close to the distribution shown in Figure 6A, is broader than the distributions shown in Figures 3A to 3F, and the shapes of the two distributions are completely different. In this way, by comparing the distribution shape of the measured light-receiving level values ​​with the distribution shape of the theoretically calculated light-receiving level values, it is possible to determine whether the calculated distance to the object is normal.

[0050] 6B is a graph showing an example of the distribution of theoretically calculated light-receiving level values ​​when highly directional light is incident on the seventh second light element 22 from a light source located 500 mm away from the first light element 21. In fact, when highly directional light is incident on the seventh second light element 22 from a light source located 500 mm away from the first light element 21, a distribution of measured light-receiving level values ​​similar to the distribution shown in FIG. 6B is obtained. As shown in FIG. 6B, light is detected by approximately four second light elements 22, from the fifth to the eighth, and the measured light-receiving level is maximum at the seventh second light element 22.

[0051] 3A to 3F, when the theoretically calculated value of the received light level is maximum near the seventh second light element 22, light is detected by nine or more second light elements 22. Conversely, when the theoretically calculated value of the received light level shows a narrow distribution, such as when light is detected by four second light elements 22, the theoretically calculated value of the received light level is maximum at the second or third second light element 22. In this way, it is possible to determine whether the calculated distance to the object is normal based on the extent of the spread of the distribution of the measured received light level values ​​and the position of the peak.

[0052] Next, the advantageous effects of the second embodiment will be described. In the second embodiment, the determination unit 55 determines whether the measured value of the distance to the object is significant. This prevents the distance to the object from being erroneously measured due to strong external light or highly directional light incident from another distance measuring sensor.

[0053] Next, a distance measuring sensor according to a modification of the second embodiment will be described. In the second embodiment, the determination unit 55 determines the significance of the measured value of the distance to the object, but in this modification, the determination unit 55 checks whether the multiple second light elements 22 are operating normally and identifies malfunctioning second light elements 22. Hereinafter, a method for checking whether the multiple second light elements 22 are operating normally and identifying malfunctioning second light elements 22 will be described with reference to FIG. 7 .

[0054] 7 is a graph showing a comparison between the distribution of measured light-receiving level values ​​and the distribution of theoretically calculated light-receiving level values ​​obtained from the measured distance to the object. The horizontal axis represents the serial numbers assigned to the second light elements 22, and the vertical axis represents the relative light-receiving level. In FIG. 7, bars with relatively dark hatching sloping upward to the right represent measured light-receiving level values. Bars with relatively light hatching sloping downward to the right represent theoretically calculated light-receiving level values ​​calculated based on the measured distance to the object, which is calculated by calculating the measured distance to the object from the weighted average of the measured light-receiving level values.

[0055] Comparing the distribution of the measured light-receiving level values ​​with the distribution of the theoretically calculated light-receiving level values ​​reveals that the light-receiving level of the fifth second light element 22 differs significantly. This leads to the estimation that some kind of malfunction has occurred in the fifth second light element 22. The determination unit 55 (FIG. 5) outputs information identifying the second light element 22 that is estimated to be malfunctioning to the output unit 54 (FIG. 5). Furthermore, if there is no significant difference in the light-receiving level for all second light elements 22 between the distribution of the measured light-receiving level values ​​and the distribution of the theoretically calculated light-receiving level values, it is estimated that no malfunction has occurred in the second light element 22.

[0056] According to this modification of the second embodiment, if there is a malfunctioning second optical element 22, it is possible to identify the malfunctioning second optical element 22. Information identifying the second optical element 22 that is presumed to be malfunctioning is output to the output unit 54, and therefore the user can perform appropriate maintenance work based on the information output to the output unit 54.

[0057] [Third Example] Next, a distance measuring sensor according to a third example will be described with reference to Fig. 8, Fig. 9A, and Fig. 9B. Below, a description of the configuration common to the distance measuring sensor according to the first example described with reference to Figs. 1 to 4 will be omitted.

[0058] In the first embodiment, the measured value of the distance to the object is calculated using the weighted average of the light reception level measurements by the plurality of second light elements 22 and the relationship between the weighted average and the distance to the object shown in Fig. 4. In contrast, in the third embodiment, the measured value of the distance to the object is calculated based on the distribution shape of the light reception level measurements by the plurality of second light elements 22. The control unit 50 of the distance measuring sensor according to the third embodiment includes a light emission control unit 51, a light reception sequencer 52, a calculation unit 53, an output unit 54, a determination unit 55, and a light reception level theoretical calculation value calculation unit 56, similar to the control unit 50 of the distance measuring sensor according to the second embodiment shown in Fig. 5.

[0059] 8 is a flowchart of the processing procedure performed by the control unit 50 (FIG. 5) of the distance measuring sensor according to the third embodiment. First, the light emission control unit 51 activates the first light element 21 (FIG. 1), and the light reception sequencer 52 sequentially activates the multiple second light elements 22 (FIG. 2) to obtain a light reception level measurement value (step S1). Next, a candidate value for the distance to the target object is set (step S2). The candidate value for the distance may be, for example, a predetermined value.

[0060] Next, the theoretically calculated light-receiving level calculation unit 56 (FIG. 5) calculates a theoretically calculated light-receiving level value for each of the second light elements 22 based on the candidate values ​​for the distance to the object (step S3). Next, the determination unit 55 (FIG. 5) performs fitting between the distribution shape of the measured light-receiving level values ​​and the distribution shape of the theoretically calculated light-receiving level values ​​(step S4). For example, the least squares method or maximum likelihood estimation method can be used to fit the two distribution shapes.

[0061] 9A and 9B are graphs showing an example of the distribution of measured light-receiving level values ​​including errors and noise, and the distribution of theoretically calculated light-receiving level values ​​when the distance to the object is 200 mm, respectively. The horizontal axis represents the serial number assigned to the second light element 22, and the vertical axis represents the relative light-receiving level. In step S4, for example, fitting is performed between the distribution shape of the measured light-receiving level values ​​shown in FIG. 9A and the distribution shape of the theoretically calculated light-receiving level values ​​shown in FIG. 9B.

[0062] It is determined whether the fitting error is minimum, and if it is not minimum, the candidate distance value is set again (step S2), and steps S3 and S4 are repeated (step S5). If the fitting error is minimum, the candidate distance value at this time is adopted as the measured distance value, and the measured distance value is output to the output unit 54 (FIG. 5) (step S6). A known algorithm such as Newton's method or steepest descent method can be used to derive the candidate distance value that minimizes the fitting error.

[0063] Next, the distribution of the measured light-receiving levels is compared with the distribution of the theoretically calculated light-receiving levels corresponding to the measured distances (step S7). The distribution of the theoretically calculated light-receiving levels has already been obtained in step S3. Based on the comparison result between the distribution of the measured light-receiving levels and the distribution of the theoretically calculated light-receiving levels, it is determined whether or not there is a malfunctioning second optical element 22 (step S8). For this determination, the method described in the second embodiment with reference to FIG. 7 can be applied.

[0064] If it is determined that there is no malfunctioning second optical element 22, the process ends. If it is determined that there is a malfunctioning second optical element 22, information identifying the malfunctioning second optical element 22 is output to the output unit 54 (FIG. 5) (step S9).

[0065] Next, we will explain the advantageous effects of Example 3. In Example 3, the least squares method, maximum likelihood estimation method, etc. are applied when performing fitting, so the accuracy of distance estimation can be improved compared to when a weighted average of measured light reception levels is used.

[0066] Next, a modified example of the third embodiment will be described. If the malfunctioning second optical element 22 is identified in step S8 (FIG. 8), the fitting process from step S2 to step S6 may be performed excluding the measured value of the light reception level of the malfunctioning second optical element 22. In this case, both the measured value of the light reception level of the malfunctioning second optical element 22 and the theoretically calculated value of the light reception level are set to zero. This can further improve the accuracy of distance measurement.

[0067] [Fourth Example] Next, a distance measuring sensor according to a fourth example will be described with reference to Fig. 10 and Fig. 11. Below, a description of the configuration common to the distance measuring sensor according to the first example described with reference to Figs. 1 to 4 will be omitted.

[0068] Fig. 10 is a schematic diagram of a distance measuring sensor 20 according to a fourth embodiment. The control unit 50 (Fig. 1) is not shown in Fig. 10. In the first embodiment (Fig. 1), a plurality of second optical elements 22 are arranged only on one side of the first straight line 40 as viewed from the first optical element 21. In contrast, in the fourth embodiment, a plurality of second optical elements 22 are arranged on both sides of the first straight line 40 as viewed from the first optical element 21.

[0069] The arrangement and configuration of the multiple second optical elements 22 arranged on both sides of the first line 40 as viewed from the first optical element 21 are the same as the arrangement and configuration of the multiple second optical elements 22 according to the first embodiment ( FIG. 1 ). That is, the second optical elements 22 on either side as viewed from the first optical element 21 have directivity inclined toward the ranging axis 23. Note that the number of second optical elements 22 arranged on one side as viewed from the first optical element 21 does not need to be the same as the number of second optical elements 22 arranged on the other side. The multiple second optical elements 22 arranged on one side as viewed from the first optical element 21 are assigned serial numbers starting from 1, and the multiple second optical elements 22 arranged on the other side are assigned negative serial numbers starting from −1.

[0070] 11 is a graph showing an example of the distribution of theoretically calculated values ​​of received light levels in the distance measuring sensor 20 (FIG. 10) according to the fourth embodiment. The horizontal axis represents the serial numbers assigned to the second light elements 22, and the vertical axis represents the theoretically calculated values ​​of received light levels as relative values. A nearly symmetrical distribution appears on both sides of the first light element 21.

[0071] In the fourth embodiment, the distance to the object can be calculated by taking a weighted average of the measured values ​​of the received light level, as in the first embodiment. Furthermore, as in the third embodiment, the distance to the object may be calculated by fitting the distribution of the measured values ​​of the received light level to the distribution of the theoretically calculated values ​​of the received light level.

[0072] Next, the advantageous effects of Example 4 will be described. As in Example 1, Example 4 also allows for more reliable measurements than when distance is calculated based on the measured light reception level measured by a single second optical element 22.

[0073] Fifth Embodiment Next, a distance measuring sensor according to a fifth embodiment will be described with reference to Fig. 12. Below, a description of the configuration common to the distance measuring sensor 20 according to the first embodiment described with reference to Figs. 1 to 4 will be omitted.

[0074] FIG. 12 is a schematic diagram of a distance measurement sensor 20 according to the fifth embodiment. While the distance measurement sensor 20 according to the first embodiment ( FIG. 1 ) includes one first optical element 21, the distance measurement sensor 20 according to the fifth embodiment includes multiple first optical elements 21. More specifically, the multiple first optical elements 21 are arranged at equal intervals along a first straight line 40 parallel to the x-axis. In FIG. 12 , the first optical elements 21 are hatched. The direction in which the emission intensity distribution 31 of each of the multiple first optical elements 21 is maximized is parallel to the z-axis and faces the same direction. That is, the distance measurement axis 23 of each of the multiple first optical elements 21 is parallel to the z-axis.

[0075] Two second optical elements 22 are disposed between two adjacent first optical elements 21. The two second optical elements 22 are disposed approximately in the center of the two adjacent first optical elements 21. The two second optical elements 22 disposed between the two first optical elements 21 have directivities that are inclined in opposite directions. For example, the directivity of one second optical element 22 is inclined from the positive direction of the z-axis to the positive side of the x-axis in the xz plane, and the directivity of the other second optical element 22 is inclined from the positive direction of the z-axis to the negative side of the x-axis in the xz plane.

[0076] The shape of the light sensitivity distribution 32 of the plurality of second light elements 22 is the same, and the absolute value of the tilt angle θ of the direction 33 in which the light sensitivity is maximum is also the same. The directivity of each of the plurality of second light elements 22 is wide enough to detect scattered light from an object 60 within the distance measurement range on the distance measurement axis 23 of at least two first light elements 21.

[0077] A single first optical element 21 and a plurality of second optical elements 22 having directivity inclined toward the distance measurement axis 23 function as a distance measurement sensor similar to the first optical element 21 and the plurality of second optical elements 22 of the distance measurement sensor 20 (FIG. 10) according to the fourth embodiment. A distance measurement sensor consisting of a single first optical element 21 and a plurality of second optical elements 22 having directivity inclined toward the distance measurement axis 23 is referred to as a "unit sensor."

[0078] In the first embodiment, the light emission control unit 51 ( FIG. 1 ) of the control unit 50 controls the light emission timing of one first light element 21, but in the fifth embodiment, the light emission sequencer 51A controls the light emission timing of multiple first light elements 21. For example, the light emission sequencer 51A causes the multiple first light elements 21 to emit light one by one in sequence. The light reception sequencer 52 operates the multiple second light elements 22 that constitute the unit sensor together with the emitting first light element 21, and sequentially obtains measured values ​​of the light reception levels of the multiple second light elements 22. Through this operation, the distance to the object 60 on the distance measurement axis 23 can be measured for each unit sensor.

[0079] Next, the second optical elements 22 that should be operated among the plurality of second optical elements 22 will be described. The second optical elements 22 at positions where scattered light from the object 60 within the measurable range on the distance measurement axis 23 of the first optical element 21 to be emitted is below the lower limit of the detection level do not need to be operated. It is sufficient to operate the second optical elements 22 that have the possibility of detecting scattered light from the object 60 within the measurable range.

[0080] 3A to 3F, when the distance to the farthest position in the measurable range is 300 mm, the second optical elements 22 farther than the 14th one do not substantially detect scattered light. Therefore, it is sufficient to operate the first through thirteenth second optical elements 22.

[0081] Next, the advantageous effects of the fifth embodiment will be described. In the fifth embodiment, the distance to the object 60 on the distance measurement axis 23 of each of the plurality of first optical elements 21 can be measured. Furthermore, since each of the plurality of second optical elements 22 belongs to a plurality of unit sensors, the total number of second optical elements 22 can be reduced compared to the configuration in which a plurality of distance measurement sensors according to the fourth embodiment ( FIG. 10 ) are simply arranged.

[0082] Next, distance measuring sensors according to several modifications of the fifth embodiment will be described with reference to Figures 13A to 16B. In the distance measuring sensor 20 according to the first embodiment (Figure 12), two separate second optical elements 22, each including a condensing lens, are disposed between two first optical elements 21. In the modifications described below, the two second optical elements 22 are realized by a single optical module.

[0083] 13A is a schematic cross-sectional view of an optical module used in a distance measuring sensor 20 according to a first modified example of the fifth embodiment. Two light receiving chips 22A and 22B are mounted on one surface of a module substrate 22D. The light receiving chips 22A and 22B are, for example, photodiodes, and electrodes such as cathodes and anodes of the light receiving chips 22A and 22B are connected to wiring formed on the module substrate 22D.

[0084] One condenser lens 22C is arranged for two light-receiving chips 22A and 22B. The optical axis of the condenser lens 22C is parallel to the ranging axis 23 (FIG. 12) of the multiple first optical elements 21. The two light-receiving chips 22A and 22B are arranged on a first straight line 40 (FIG. 12). The two light-receiving chips 22A and 22B are also arranged at positions offset at an equal distance from the optical axis of the condenser lens 22C. By arranging the light-receiving chips 22A and 22B at positions offset from the optical axis of the condenser lens 22C, an optical module is realized that has symmetric directivity in two directions with respect to the optical axis of the condenser lens 22C. One light-receiving chip 22A and the condenser lens 22C constitute one second optical element 22, and the other light-receiving chip 22B and the condenser lens 22C constitute the other second optical element 22.

[0085] Generally, coma aberration occurs when the light-receiving chips 22A and 22B are positioned at positions offset from the optical axis of the condenser lens 22C. In this modified example, since it is not necessary to condense scattered light from the object 60 (FIG. 12) to a single point on the light-receiving chips 22A and 22B, coma aberration does not become a fundamental problem that makes the design impossible.

[0086] Fig. 13B is a schematic cross-sectional view of an optical module used in a distance measuring sensor 20 according to a second modified example of the fifth embodiment. While a condensing lens 22C is used as the condensing optical component in the first modified example shown in Fig. 13A, a concave mirror 22E is used as the condensing optical component in this modified example. Furthermore, a transparent substrate is used as the module substrate 22D in this modified example. Scattered light transmitted through the module substrate 22D is condensed by the concave mirror 22E and enters the light receiving chip 22A or the light receiving chip 22B.

[0087] In the first modified example shown in FIG. 13A and the second modified example shown in FIG. 13B, the second optical element 22 can be made smaller than in a configuration in which two separate second optical elements 22, each including a condenser lens, are arranged. Furthermore, in the fifth embodiment ( FIG. 12 ), alignment is required to adjust the direction of directivity for each of the two separate second optical elements 22. In contrast, in the first modified example shown in FIG. 13A and the second modified example shown in FIG. 13B, the relative positional relationship between the directivity of one second optical element 22 composed of one light-receiving chip 22A and a condenser lens 22C and the other second optical element 22 composed of the other light-receiving chip 22B and a condenser lens 22C has already been adjusted. This simplifies the alignment procedure during the manufacture of the distance measurement sensor 20.

[0088] Fig. 14A is a schematic plan view of the light receiving section of an optical module used in a distance measuring sensor 20 according to a third modified example of the fifth embodiment, and Fig. 14B is a cross-sectional view taken along dashed line 14B-14B in Fig. 14A. In the first modified example shown in Fig. 13A and the second modified example shown in Fig. 13B, two light receiving chips 22A and 22B are mounted on a module substrate 22D. In contrast, the second optical element 22 according to the third modified example has two photodiodes provided on a single common substrate 22G.

[0089] Two n-type cathode regions 22H are provided on a p-type common substrate 22G. The p-type common substrate 22G functions as a common anode region for the two photodiodes. A pin junction is formed between the cathode region 22H and the anode region (common substrate 22G). The pin junction portion functions as an active region. A cathode electrode 22I is provided on each of the two cathode regions 22H, and a common anode electrode 22J is provided on the common substrate 22G.

[0090] The n-type region and the p-type region may be reversed so that the cathode region of the two photodiodes is common.

[0091] Figure 15A is a schematic plan view of an optical module used in a distance measuring sensor 20 according to a fourth modified example of the fifth embodiment, and Figure 15B is a cross-sectional view taken along dashed line 15B-15B in Figure 15A. In the third modified example shown in Figures 14A and 14B, a p-type common substrate 22G is shared as the anode region for two photodiodes. In contrast, in the fourth modified example, two independent p-type anode regions 22L are formed on an n-type common substrate 22K. An n-type cathode region 22H is formed within each of the two anode regions 22L.

[0092] A cathode electrode 22I is provided in each of the two cathode regions 22H, and an anode electrode 22J is provided in each of the two anode regions 22L.

[0093] Fig. 16A is a schematic plan view of an optical module used in a distance measuring sensor 20 according to a fifth modified example of the fifth embodiment, and Fig. 16B is a cross-sectional view taken along dashed line 16B-16B in Fig. 16A. While an n-type common substrate 22K is used in the fourth modified example shown in Figs. 15A and 15B, an SOI substrate is used in the fifth modified example. The SOI substrate includes an n-type or p-type support substrate 22M, a buried oxide film 22N, and a semiconductor layer. The semiconductor layer includes two p-type anode regions 22L separated by an element isolation region 22P.

[0094] An n-type cathode region 22H is formed in each of the two anode regions 22L. A cathode electrode 22I is provided in each of the two cathode regions 22H, and an anode electrode 22J is provided in each of the two anode regions 22L.

[0095] In the third, fourth, and fifth modified examples described with reference to Figures 14A to 16B, two photodiodes are configured on a single chip, making it possible to further miniaturize the optical module compared to the first modified example shown in Figure 13A and the second modified example shown in Figure 13B.

[0096] In the fifth embodiment and its modifications, the light receiving portion of the second optical element 22 is configured as a photodiode, but it may be configured as another light receiving element, such as a phototransistor or a CdS cell.

[0097] Next, another modification of the fifth embodiment will be described. In the fifth embodiment, a plurality of first optical elements 21 ( FIG. 12 ) are arranged at equal intervals. Furthermore, a plurality of second optical elements 22 having directivity tilted from the positive direction of the z-axis toward the positive side of the x-axis in the xz plane are arranged at equal intervals, and a plurality of second optical elements 22 having directivity tilted from the positive direction of the z-axis toward the negative side of the x-axis in the xz plane are also arranged at equal intervals. In this modification, the arrangement of the plurality of first optical elements 21 is not necessarily equally spaced. Similarly, the arrangement of the plurality of second optical elements 22 is not necessarily equally spaced. If the distance from the first optical element 21 to the second optical element 22 is known, the theoretical calculation value of the received light level can be obtained from Equation (1).

[0098] Sixth Embodiment Next, with reference to FIG. 17, a robot equipped with the distance measuring sensors according to the first to fifth embodiments will be described.

[0099] 17 is a schematic side view of an articulated robot 70 equipped with a distance measurement sensor 20 according to any one of the first to fifth embodiments. The base of an articulated robot arm 72 is fixed to a base 71, and an actuator 73 is attached to the tip of the articulated robot arm 72. Distance measurement sensors 20 are attached to the arm portion and tip of the articulated robot arm 72, respectively. The distance measurement sensor 20 calculates the distance to obstacles around the articulated robot 70.

[0100] Next, the advantageous effects of the sixth embodiment will be described. In the sixth embodiment, the distance measurement sensor 20 is a distance measurement sensor 20 according to any one of the first to fifth embodiments. Therefore, the distance measurement sensor 20 is less susceptible to the influence of external light from a distance or highly directional light from other sensors, and can perform distance measurement with a certain degree of accuracy even if one of the multiple second light elements 22 (see FIG. 1, etc.) malfunctions. This makes it less likely that the articulated robot 70 will come into contact with surrounding obstacles, thereby improving safety.

[0101] In the sixth embodiment, the distance measurement sensor 20 is mounted on the articulated robot 70, but it may also be mounted on a service robot or the like that moves autonomously within a store and carries luggage.

[0102] The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects resulting from similar configurations of multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible.

[0103] Based on the above examples described in this specification, the following invention is disclosed. <1> A light receiving apparatus comprising: at least one first optical element performing one of an emitting operation and a receiving operation, and a plurality of second optical elements performing the other operation; and a control unit that controls the emitting and receiving operations of the first optical element and the plurality of second optical elements, wherein active regions of the plurality of second optical elements are arranged along an imaginary first straight line passing through the active region of the first optical element, the first optical element has directivity in the direction of a ranging axis perpendicular to the first straight line, and each of the plurality of second optical elements has directivity broader than the directivity of the first optical element, the first optical element and the plurality of second optical elements are arranged such that a portion of light emitted from one of the first optical element and the second optical elements and scattered by an object is incident on the other optical element, and each of the plurality of second optical elements has directivity inclined toward the ranging axis, and the control unit operates the first optical element and the plurality of second optical elements to obtain a light receiving level measured due to each of the plurality of second optical elements as a light receiving level measurement value due to the second optical element, A distance measuring sensor that calculates a distribution of the received light level measurement values ​​from the received light level measurement values ​​attributable to each of the plurality of second light elements and the positions of each of the plurality of second light elements, and calculates a measurement value of the distance to the object from the distribution of the received light level measurement values.

[0104] <2> The distance measuring sensor described in <1>, wherein the first light element performs a light emitting operation, each of the plurality of second light elements performs a light receiving operation, and the control unit operates the first light element and the plurality of second light elements to measure the light receiving level at each of the plurality of second light elements, thereby acquiring the light receiving level measurement value attributable to each of the second light elements.

[0105] <3> The distance measuring sensor described in <1>, wherein the first optical element performs a light receiving operation, each of the plurality of second optical elements performs a light emitting operation, and the control unit operates each of the plurality of second optical elements in sequence to measure the light receiving level at the first optical element, thereby acquiring the light receiving level measurement value attributable to each of the second optical elements.

[0106] <4> A ranging sensor described in any one of <1> to <3>, wherein the control unit calculates a measurement value of the distance to the object based on a weighted average value obtained by weighting and averaging the light reception level measurement values ​​attributable to each of the plurality of second optical elements with an index representing the distance from the active region of the first optical element to each of the plurality of second optical elements.

[0107] <5> The control unit calculates the light reception level caused by the second light element from the measurement value of the distance to the object obtained based on the weighted average value to obtain a theoretical calculation value of the light reception level, and compares the distribution of the measurement value of the light reception level with the distribution of the theoretical calculation value of the light reception level to determine the significance of the measurement value of the distance to the object.

[0108] <6> The distance measuring sensor described in <5>, wherein the control unit determines whether any of the plurality of second optical elements is malfunctioning based on a comparison result between the distribution of the measured light receiving level values ​​and the distribution of the theoretically calculated light receiving level values, and identifies the malfunctioning element among the second optical elements.

[0109] <7> A distance measuring sensor described in any one of <1> to <3>, wherein the control unit calculates a plurality of theoretically calculated values ​​of received light levels from a plurality of candidate values ​​of the distance to the object, fits the distribution shape of the measured light level values ​​to the distribution shape of the theoretically calculated values ​​of received light levels calculated from each of the plurality of candidate values ​​of the distance to the object, and calculates a measured value of the distance to the object based on the fitting results.

[0110] <8> The control unit compares the distribution of the light reception level measurement values ​​with the distribution of the light reception level theoretical calculation values ​​corresponding to the measurement values ​​of the distance to the object, and determines whether any of the multiple second light elements is malfunctioning based on the comparison result, and identifies the malfunctioning element among the second light elements.

[0111] <9> The distance measuring sensor described in any one of <1> to <8>, wherein a plurality of the first optical elements are arranged along the first straight line, and the plurality of second optical elements include the second optical elements arranged two by two between the plurality of first optical elements lined up along the first straight line, and the directions in which the light emission intensity or light receiving sensitivity of the two second optical elements arranged between the first optical elements are maximum are inclined in mutually opposite directions with respect to a plane perpendicular to the first straight line.

[0112] <10> The distance measurement sensor described in <9>, wherein the two second optical elements arranged between the plurality of first optical elements aligned along the first straight line include two active regions aligned along the first straight line and a focusing optical component shared by the two active regions.

[0113] <11> The distance measuring sensor according to <10>, wherein the active regions of the two second optical elements arranged between the plurality of first optical elements aligned along the first straight line are formed on a common substrate.

[0114] 20 Distance measuring sensor 21 First optical element 22 Second optical element 22A, 22B Light receiving chip 22C Condenser lens 22D Module substrate 22E Concave mirror 22G P-type common substrate 22H N-type cathode region 22I Cathode electrode 22J Anode electrode 22K N-type common substrate 22L P-type anode region 22M Support substrate 22N Buried oxide film 22P Element isolation region 23 Distance measuring axis 31 Distribution of light emission intensity of first optical element 32 Distribution of light receiving sensitivity of second optical element 33 Direction in which light receiving sensitivity is maximum 40 First straight line 50 Control unit 51 Light emission control unit 51A Light emission sequencer 52 Light receiving sequencer 53 Calculation unit 54 Output unit 55 Determination unit 56 Light receiving level theoretical calculation value calculation unit 60 Object 70 Articulated robot 71 Base 72 Articulated robot arm 73 Actuator

Claims

1. A device comprising: at least one first optical element performing one of an emitting operation and a receiving operation, and a plurality of second optical elements performing the other operation; and a control unit for controlling the emitting and receiving operations of the first optical element and the plurality of second optical elements, wherein the plurality of second optical elements are arranged along an imaginary first straight line passing through the first optical element, the first optical element has directivity in the direction of a distance measurement axis perpendicular to the first straight line, each of the plurality of second optical elements has directivity wider than the directivity of the first optical element, the first optical element and the plurality of second optical elements are arranged such that a portion of light emitted from one of the first optical element and the second optical element and scattered by an object enters the other optical element, each of the plurality of second optical elements has directivity inclined toward the distance measurement axis, and the control unit operates the first optical element and the plurality of second optical elements to obtain a light receiving level measured due to each of the plurality of second optical elements as a light receiving level measurement value due to the second optical element, A distance measuring sensor that calculates a distribution of the received light level measurement values ​​from the received light level measurement values ​​attributable to each of the multiple second light elements and the positions of each of the multiple second light elements, and calculates a measurement value of the distance to the object from the distribution of the received light level measurement values.

2. A distance measuring sensor as described in claim 1, wherein the first light element performs an emitting operation, each of the multiple second light elements performs a light receiving operation, and the control unit operates the first light element and the multiple second light elements to measure the light receiving level at each of the multiple second light elements, thereby obtaining the light receiving level measurement value attributable to each of the second light elements.

3. A distance measuring sensor as described in claim 1, wherein the first optical element performs a light receiving operation, each of the plurality of second optical elements performs a light emitting operation, and the control unit acquires the light receiving level measurement value attributable to each of the second optical elements by operating each of the plurality of second optical elements in sequence and measuring the light receiving level at the first optical element.

4. A distance measuring sensor as described in any one of claims 1 to 3, wherein the control unit determines a measurement value of the distance to the object based on a weighted average value obtained by weighting the light receiving level measurement value attributable to each of the multiple second light elements with an index representing the distance from the first light element to each of the multiple second light elements.

5. The distance measuring sensor described in claim 4, wherein the control unit calculates the light reception level attributable to the second light element from the measured value of the distance to the object obtained based on the weighted average value to obtain a theoretical calculated value of the light reception level, and compares the distribution of the measured light reception level values ​​with the distribution of the theoretically calculated light reception level values ​​to determine the significance of the measured value of the distance to the object.

6. A distance measuring sensor as described in claim 5, wherein the control unit determines whether any of the plurality of second optical elements is malfunctioning based on a comparison result between the distribution of the measured light receiving level values ​​and the distribution of the theoretically calculated light receiving level values, and identifies the malfunctioning elements among the second optical elements.

7. A distance measuring sensor as described in any one of claims 1 to 3, wherein the control unit calculates a plurality of theoretically calculated values ​​of the light receiving level from a plurality of candidate values ​​of the distance to the object, performs fitting between the distribution shape of the measured light receiving level values ​​and the distribution shape of the theoretically calculated values ​​of the light receiving level calculated from each of the plurality of candidate values ​​of the distance to the object, and calculates a measured value of the distance to the object based on the fitting result.

8. The distance measuring sensor of claim 7, wherein the control unit compares the distribution of the measured light receiving level values ​​with the distribution of the theoretically calculated light receiving level values ​​corresponding to the measured values ​​of the distance to the object, and determines whether or not any of the plurality of second light elements are malfunctioning based on the comparison result, and identifies the malfunctioning elements among the second light elements.

9. A distance measuring sensor as described in any one of claims 1 to 8, wherein the first optical elements are arranged in multiples along the first straight line, the multiple second optical elements include second optical elements arranged in pairs between the multiple first optical elements lined up along the first straight line, and the directions in which the light emission intensity or light receiving sensitivity of the two second optical elements arranged between the first optical elements are maximum are inclined in opposite directions to each other with respect to a plane perpendicular to the first straight line.

10. The distance measurement sensor described in claim 9, wherein the two second optical elements arranged between the multiple first optical elements aligned along the first straight line include two active areas aligned along the first straight line and a focusing optical component shared by the two active areas.

11. The distance measuring sensor according to claim 10, wherein the active regions of two of the second optical elements arranged between a plurality of the first optical elements aligned along the first straight line are formed on a common substrate.

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