Object detection sensor and object detection method

Abstract

At least four first optical elements are arranged on the virtual plane. At least one second optical element is disposed on the virtual plane. One of the first optical element and the second optical element is a light-emitting element, and the other is a light-receiving element. A minimum unit is composed of at least four first optical elements and one second optical element. The directivity characteristics of the four first optical elements in the smallest unit are the same, and the directivity characteristics of the second optical elements are different from the directivity characteristics of the first optical elements when a straight line extending from the second optical elements in the normal direction of the virtual plane is taken as a reference axis. The inclination angle is 15 degrees or less when the illuminance or the light receiving sensitivity in the direction inclined with respect to the reference axis is 1 / 2 of the illuminance or the light receiving sensitivity in the direction of the reference axis. The four first optical elements of the smallest unit are not arranged on a common straight line passing through the second optical elements, and are not arranged on a common circumference centered on the second optical elements. The calculation unit determines the distance from the virtual plane to the object on the reference axis, the tilt angle of the surface of the object, and the tilt azimuth angle on the basis of the measured values of the received light intensities when the first optical element and the second optical element of the minimum unit are operated.

Description

Technical Field

[0001] The present invention relates to an object detection sensor and an object detection method. Background Art

[0002] The following sensor is well known: a sensor that uses a light-receiving element to detect light reflected by an object in the light radiated from a light-emitting element, thereby detecting the posture of the object and the distance to the object (Patent Document 1). The sensor described in Patent Document 1 includes two light-emitting elements with strong astigmatism and one light-receiving element with strong directivity. One light-receiving element and two light-emitting elements are arranged on a straight line. Light diffusely reflected by the surface of the object in the irradiated light from the light-emitting element is received by the light-receiving element. The distance from the light-receiving element to the object is derived by utilizing the fact that the distance between the light-emitting element and the object is different in the two light-emitting elements and the illumination at the position of the object is different.

[0003] Furthermore, by arranging light-emitting elements at equal distances on both sides of the light-receiving element, and arranging four light-emitting elements in total, the inclination of the surface of the object along the arrangement direction of the light-emitting elements can also be determined.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Publication No. 62-17163 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The sensor described in Patent Document 1 can determine the tilt of an object with respect to the arrangement direction of light-emitting elements, but cannot determine tilts with respect to other directions.

[0009] An object of the present invention is to provide an object detection sensor and an object detection method capable of determining the distance to an object and the tilted orientation of the surface of the object.

[0010] Solutions for solving problems

[0011] According to one aspect of the present invention, there is provided an object detection sensor comprising:

[0012] at least four first optical elements arranged on the virtual plane;

[0013] at least one second optical element disposed on the virtual plane; and

[0014] Operation unit,

[0015] One of the first optical element and the second optical element is a light emitting element, and the other is a light receiving element.

[0016] A minimum unit is formed by at least four of the first optical elements and one of the second optical elements,

[0017] The four first optical elements of the minimum unit have the same directional characteristics. Regarding the directional characteristics of the second optical element, when a straight line extending from the second optical element along the normal direction of the virtual plane is used as a reference axis, the inclination angle at which the illuminance or light sensitivity in a direction inclined relative to the reference axis is 1 / 2 of the illuminance or light sensitivity in the direction of the reference axis is 15° or less.

[0018] The four first optical elements of the minimum unit are not arranged on a common straight line passing through the second optical element, nor are they arranged on a common circumference centered on the second optical element.

[0019] The calculation unit calculates the distance from the virtual plane to the object on the reference axis, the inclination angle of the normal direction of the surface of the object relative to the reference axis, and the inclination azimuth angle based on the measured value of the light intensity when the first light element and the second light element, which are the minimum units, are operated.

[0020] According to another aspect of the present invention, there is provided an object detection method, wherein the first optical element and the second optical element, which are minimum units consisting of each first optical element and the second optical element among at least four first optical elements arranged on a common virtual plane, are operated to detect an object on a reference axis extending from the second optical element in the normal direction of the virtual plane. In the object detection method,

[0021] One of the first optical element and the second optical element is a light emitting element, and the other is a light receiving element.

[0022] The four first optical elements of the minimum unit have the same directional characteristics, and the directional characteristics of the second optical element have an inclination angle of 15° or less when the illuminance or light sensitivity in a direction inclined relative to the reference axis is 1 / 2 of the illuminance or light sensitivity in the direction of the reference axis.

[0023] The four first optical elements of the minimum unit are not arranged on a common straight line passing through the second optical element, nor are they arranged on a common circumference centered on the second optical element.

[0024] A brightness measurement value when the object is used as a new light source is obtained based on light emitted from one of the first and second optical elements of the minimum unit, reflected by the object, and received by the other element.

[0025] Based on the measured value, at least one of the reflectivity of the surface of the object, the distance from the virtual plane to the object on the reference axis, the tilt angle of the surface of the object relative to the reference axis, and the tilt azimuth angle of the surface of the object is calculated.

[0026] Effects of the Invention

[0027] By configuring the four first optical elements as the minimum unit not on a common straight line passing through the second optical element, nor on a common circle centered on the second optical element, the distance to the object and the tilt direction of the surface of the object can be calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] [ Figure 1 ] Figure 1 A is a schematic perspective view of the object detection sensor of the first embodiment. Figure 1 B is a diagram showing an example of the positional relationship between four first optical elements and one second optical element in a plan view.

[0029] [ Figure 2 ] Figure 2 It is a diagram showing the positional relationship and coordinate system among a first optical element, a second optical element, and an object.

[0030] [ Figure 3 ] Figure 3 Schematic diagram showing the directional characteristics of the first optical element and the second optical element.

[0031] [ Figure 4 ] Figure 4 This is a flowchart showing a process executed by the computing unit of the object detection sensor according to the first embodiment.

[0032] [ Figure 5 ] Figure 5 This is a diagram showing the planar positional relationship between four first optical elements and one second optical element of an object detection sensor according to a modified example of the first embodiment.

[0033] [ Figure 6 ] Figure 6 This is a schematic perspective view of an object detection sensor according to another modified example of the first embodiment.

[0034] [ Figure 7 ] Figure 7 This is a diagram showing the planar positional relationship between the first optical element and the second optical element of the object detection sensor of the second embodiment.

[0035] [ Figure 8 ] Figure 8 A and Figure 8B is a diagram showing the planar positional relationship between the first optical element and the second optical element of the object detection sensor according to the third embodiment and its modified example.

[0036] [ Figure 9 ] Figure 9 It is a diagram showing the planar positional relationship between the first optical element and the second optical element of the object detection sensor of the fourth embodiment.

[0037] [ Figure 10 ] Figure 10 This is a schematic plan view showing the positional relationship between a plurality of first optical elements and a second optical element included in one minimum unit among a plurality of minimum units of the object detection sensor according to the fifth embodiment.

[0038] [ Figure 11 ] Figure 11 : is a graph showing the relationship between the ratio R (Equation (8)) and the distance z when two pairs of first optical elements are operated.

[0039] [ Figure 12 ] Figure 12 1 is a flowchart showing a process executed by the computing unit of the object detection sensor according to the fifth embodiment. DETAILED DESCRIPTION

[0040] [First embodiment]

[0041] Reference Figures 1 to 4 The object detection sensor and the object detection method of the first embodiment are described with reference to the accompanying drawings.

[0042] Figure 1 A is a schematic three-dimensional diagram of the object detection sensor of the first embodiment. The object detection sensor of the first embodiment includes four first optical elements 31, one second optical element 32, and a computing unit 40. Each of the four first optical elements 31 is a light-emitting element that emits light under the control of the computing unit 40. As the first optical element 31, for example, a light-emitting diode (LED), a vertical cavity surface emitting laser (VCSEL), etc. are used. The second optical element 32 is a light-receiving element that outputs an electrical signal corresponding to the intensity of the received light. The electrical signal is read into the computing unit 40. As the second optical element 32, for example, a photodiode, a phototransistor, a CdS element, etc. are used. Figure 1 In A, the light receiving element is hatched.

[0043] Four first optical elements 31 and one second optical element 32 are arranged on a common virtual plane 21. For example, the four first optical elements 31 and the one second optical element 32 are mounted on a flat surface of a substrate 20. In this case, the mounting surface of the substrate 20 is substantially aligned with the virtual plane 21. The object detection sensor of the first embodiment detects an object 50 located on a virtual straight line (hereinafter referred to as the reference axis 25) extending in the normal direction of the virtual plane 21 through the second optical element 32. Specifically, based on the intensity of light radiated from each first optical element 31, reflected by the object 50, and incident on the second optical element 32, the distance from the virtual plane 21 to the object 50 and the posture of the object 50 are detected. Here, "passing through the second optical element 32" means passing through the geometric center of the light-receiving area of ​​the second optical element 32.

[0044] Figure 1 B is a diagram showing an example of the positional relationship of four first optical elements 31 and one second optical element 32 when viewed from above. The four first optical elements 31 are not arranged on a common straight line passing through the second optical element 32, nor are they arranged on a common circumference centered on the second optical element 32. That is, when a straight line SL passing through the second optical element 32 and one first optical element 31 is drawn, at least one of the other three first optical elements 31 is arranged at a position deviated from the straight line SL. Figure 1 In the example shown in B, two first optical elements 31 are arranged at positions deviated from the straight line SL. In addition, when a circle C passing through one first optical element 31 is drawn with the second optical element 32 as the center, at least one of the other three first optical elements 31 is arranged at a position deviated from the circle C. Figure 1 In the example shown in B, the two first optical elements 31 are arranged at positions deviated from the circumference C.

[0045] Here, the geometric center of the light-emitting area of ​​the first optical element 31 is used as a reference to determine whether the first optical element 31 is located on the straight line SL or on the circumference C. The geometric center of the light-receiving area of ​​the second optical element 32 is used as a reference to determine whether the second optical element 32 is located on the straight line SL. The circumference centered on the second optical element 32 refers to the circumference centered on the geometric center of the light-receiving area of ​​the second optical element 32. Due to this configuration, the distance between the second optical element 32 and at least one first optical element 31 is different from the distance between the second optical element 32 and the other three first optical elements 31. Each of the four first optical elements 31 and one second optical element 32 constitutes a total of four light-receiving and light-emitting pairs.

[0046] Next, refer to Figure 2 The coordinate system and definitions of various parameters used in this specification are explained. Figure 2: is a diagram showing the positional relationship and coordinate system of the first optical element 31i, the second optical element 32, and the object 50. The xy plane of the xyz orthogonal coordinate system corresponds to the virtual plane 21 ( Figure 1 ), a second optical element 32 is arranged at the origin O. The z-axis corresponds to the reference axis 25. In addition, a left-handed coordinate system is adopted as the xyz orthogonal coordinate system.

[0047] When the four first optical elements 31 are numbered sequentially starting from 1, the i-th first optical element 31 is denoted as 31i. The x-coordinate and y-coordinate of the first optical element 31i are denoted as a xi 、a yi The distance from the origin O to the first optical element 31i is marked as r i The azimuth angle of the position of the first optical element 31 when the x-axis is the reference direction is represented by θ ri .

[0048] The intersection of the surface of the object 50 facing the origin O and the reference axis 25 (hereinafter referred to as the representative point of the object 50) is denoted as P. The distance from the origin O (the second optical element 32) to the representative point P of the object 50 is denoted as z. In this specification, the distance z from the second optical element 32 to the representative point P of the object 50 may be simply referred to as the distance z from the second optical element 32 to the object 50. The unit vector from the representative point P of the object 50 to the first optical element 31i is denoted as n. i . The unit vector n i The angle formed with the reference axis 25 is denoted as θ i .

[0049] The unit normal vector of the surface of the object 50 at the position of the representative point P is denoted by n. s . The unit normal vector n s The angle with the reference axis 25 is marked as The angle is called the tilt angle of the object 50. s The angle between the vertical projection image on the xy plane and the x-axis is marked as The angle This is referred to as the tilt azimuth angle of the surface of the object 50 .

[0050] Figure 3Schematic diagram showing the directional characteristics of the first optical element 31 and the second optical element 32. The directional characteristics DC1 of the first optical element 31 and the directional characteristics DC2 of the second optical element 32 are shown in a graph. The tilt angle relative to the positive direction of the z-axis is marked as θ. In the first optical element 31, the light intensity is maximum at θ = 0° (front direction), and the light intensity decreases as the tilt angle θ increases. The tilt angle θ at which the light intensity is 1 / 2 of the light intensity in the front direction is called the half-value half-angle θ. 1 / 2 In the second optical element 32, the light receiving sensitivity is the highest when θ = 0° (front direction), and the light receiving sensitivity decreases as the tilt angle θ increases. The tilt angle θ at which the light receiving sensitivity is 1 / 2 of the light receiving sensitivity in the front direction is called the half-value half angle θ. 1 / 2 .

[0051] The directional characteristics of the first optical element 31 are wider than the directional characteristics of the second optical element 32. For example, the directional characteristics of the first optical element 31 are wider than the directional characteristics of the second optical element 32. Figure 1 A) Wide-angle directional characteristics that allow for irradiation of light of sufficient intensity. The second optical element 32 has a sharp directional characteristic that is sufficiently sensitive to reflected light from an object that is significantly deviated from the reference axis 25. For example, the half-value half angle θ of the directional characteristic of the second optical element 32 is 1 / 2 It is preferably 15° or less, more preferably 10° or less, and most preferably 5° or less.

[0052] When the directional characteristics of the first optical element 31 do not depend on the azimuth angle, generally speaking, the directional characteristics LD(θ) of the first optical element 31 can be approximated by the following equation.

[0053] [Number 1]

[0054] LD(θ)=cos n θ…(1)

[0055] Here, n is a parameter determined by the directional characteristics of the first optical element 31. The larger n is, the sharper the directional characteristics are.

[0056] The luminous intensity of the front direction of the i-th first light element 31i is marked as G i , the light receiving sensitivity of the second optical element 32 is denoted by C. The reflectivity of the surface of the object 50 is denoted by α. The light intensity LIi at the representative point P is expressed by the following equation. In addition, the directivity characteristics LD(θ) of the four first optical elements 31 are the same.

[0057] [Number 2]

[0058]

[0059] The intensity of light detected by the second optical element 32 , that is, the brightness Li of the representative point P when the representative point P is regarded as a new light source from the second optical element 32 , is expressed by the following equation.

[0060] [Number 3]

[0061]

[0062] The denominator z on the right side of formula (3) β The item shows that as the distance z increases, the field of view of the second optical element 32 becomes wider, and thus the object 50 ( Figure 1 When light is irradiated to a wide area of ​​the surface of the object 50 and the surface of the object 50 is larger than the field of view of the second optical element 32, light is received in the entire field of view of the second optical element 32 even if the distance z increases. In this case, z β The influence of the term is reduced. According to the shape and size of the object 50, the half-value half-angle θ of the directional characteristic of the second optical element 32 1 / 2 In fact, β in formula (3) takes any value within the range of 0 to 2.

[0063] The parameter CαG on the right side of formula (3) i / z β It is common among the four first optical elements 31, so in equation (3), the unknown number is the parameter CαG i / z β , distance z, tilt azimuth Tilt angle These four equations generate the equations (3) i = 1, 2, 3, and 4. Since the four first optical elements 31 are not arranged on a common straight line passing through the second optical element 32, nor are they arranged on a common circle centered on the second optical element 32, the four equations are linearly independent. Therefore, the calculation unit 40 can calculate the parameter CαG by solving the four-variable simultaneous equations. i / z β , distance z, tilt azimuth Tilt angle

[0064] Next, refer to Figure 4 A method of detecting an object by the object detection sensor according to the first embodiment will be described. Figure 4 The calculation unit 40 ( Figure 1 A) Flowchart of the process performed.

[0065] Operation unit 40 ( Figure 1A) The four first optical elements 31 are sequentially illuminated, and the intensity of the light received by the second optical element 32 is measured for each first optical element 31 (step SA1). The four measured values ​​measured by the second optical element 32 are substituted into equation (3) to generate a four-variable simultaneous equation. By solving the four-variable simultaneous equation, the distance z and the tilt azimuth angle are obtained. Tilt angle (Step SA2).

[0066] Next, the advantageous effects of the first embodiment will be described.

[0067] In the first embodiment, the distance z, the tilt azimuth angle, and the tilt angle z can be obtained by using four first optical elements 31 and one second optical element 32. Tilt angle That is, not only the tilt angle with respect to a specific direction, but also the direction in which the surface of the object 50 is tilted can be obtained.

[0068] Next, an object detection sensor according to a modified example of the first embodiment will be described.

[0069] In the object detection sensor of the first embodiment, the directional characteristics LD(θ) of the four first optical elements 31 are isotropic and independent of the azimuth angle. However, this is not necessarily required. For example, if the directional characteristics can be transformed into a form independent of the azimuth angle through coordinate transformation, the directional characteristics do not necessarily need to be isotropic.

[0070] For example, in Figure 3 The half-value half-angle θ in the xz plane is shown 1 / 2 is the half-value half-angle θ in the yz plane 1 / 2 If the value of the y-axis is set to 2 times, the half-value half-angle θ in the xz plane is 1 / 2 and half-value half-angle θ in the yz plane 1 / 2 Therefore, by performing coordinate transformation, simultaneous equations of the same form as equation (3) can be obtained.

[0071] Next, refer to Figure 5 An object detection sensor according to another modified example of the first embodiment will be described. Figure 5 1 is a diagram showing the planar positional relationship between four first optical elements 31 and one second optical element 32 of the object detection sensor according to this modification.

[0072] In the object detection sensor of the first embodiment, the four first optical elements 31 ( Figure 1 B) None of the three are arranged in a straight line. Figure 5In the modified example shown, three first optical elements 31 and one second optical element 32 are arranged on a straight line SL, and the remaining first optical element 31 is arranged at a position deviated from the straight line SL. In this case as well, as long as the four-variable simultaneous equations consisting of the four equations (3) defined for each of the four first optical elements 31 are linearly independent, the distance z and the tilt azimuth can be calculated in the same way as in the first embodiment. Tilt angle

[0073] Next, refer to Figure 6 An object detection sensor according to another modified example of the first embodiment will be described. Figure 6 This is a schematic perspective view of the object detection sensor according to this modification.

[0074] In the first embodiment ( Figure 1 In A), four first optical elements 31 are light emitting elements, and one second optical element 32 is a light receiving element. In contrast, in this modification, one second optical element 32 is a light emitting element, and four first optical elements 31 are light receiving elements. Figure 6 The directional characteristics of the first optical element 31 and the second optical element 32 are the same as those of the first optical element 31 and the second optical element 32 of the object detection sensor of the first embodiment.

[0075] That is, the second optical element 32 irradiates light mainly toward the object 50 located on the reference axis 25, and does not substantially irradiate light in a direction significantly deviated from the reference axis 25. For example, the half-value half-angle θ of the directional characteristic of the light radiated from the second optical element 32 is 1 / 2 It is preferably 15° or less, more preferably 10° or less, and most preferably 5° or less.

[0076] In addition, the directional characteristics of the light receiving sensitivity of the four first optical elements 31 are wider than the directional characteristics of the second optical element 32. For example, for the object 50 ( Figure 1 A) The reflected light has sufficient light-receiving sensitivity.

[0077] During object detection, the second optical element 32 emits light, and the four first optical elements 31 receive the reflected light from the object 50. In this modified example, the brightness of the representative point P on the surface of the object 50 is expressed by equation (3). Therefore, in this modified example, the distance z and the tilt azimuth can be calculated in the same way as in the first embodiment. Tilt angle

[0078] [Second embodiment]

[0079] Next, refer to Figure 7The object detection sensor of the second embodiment is described. Figure 1 A to Figure 4 The common structure of the object detection sensor of the first embodiment illustrated in the accompanying drawings is omitted.

[0080] Figure 7 This figure shows the planar positional relationship between the first optical element 31 and the second optical element 32 of the object detection sensor of the second embodiment. In the second embodiment, four first optical elements 31 and one second optical element 32 are arranged on the virtual plane 21, similarly to the first embodiment.

[0081] In the first embodiment ( Figure 1 In B), none of the four first optical elements 31 are arranged in a straight line, nor are the four first optical elements 31 arranged on a common circumference centered on the second optical element 32. In the second embodiment, the four first optical elements 31 are arranged so as to satisfy not only this condition but also the following condition.

[0082] In the second embodiment, two of the four first optical elements 31a1 and 31a2 are arranged at point-symmetrical positions with respect to the second optical element 32, and the other two first optical elements 31b1 and 31b2 are also arranged at point-symmetrical positions with respect to the second optical element 32. The distance from the second optical element 32 to each of the first optical elements 31a1 and 31a2 is marked as r. a The distance from the second optical element 32 to each of the first optical elements 31b1 and 31b2 is marked as r b The angle formed by the straight line passing through the two first optical elements 31a1 and 31a2 and the straight line passing through the other two first optical elements 31b1 and 31b2 is marked as δ. The angle δ is greater than 0° and less than 180°.

[0083] In the second embodiment, two first optical elements 31a1 and 31a2 constitute one first optical element pair 31a, and the other two first optical elements 31b1 and 31b2 constitute another first optical element pair 31b.

[0084] When formula (3) is applied to the first optical element 31a1, the following formula is obtained.

[0085] [Number 4]

[0086]

[0087] When formula (3) is applied to the first optical element 31a2, the following formula is obtained.

[0088] [Number 5]

[0089]

[0090] In formula (4) and formula (5), since G a1 =G a2 ,θ ra1 +θ ra2 =180°, so the following equation is obtained according to equations (4) and (5).

[0091] [Number 6]

[0092]

[0093] Similarly, the following equations are obtained for the first optical elements 31b1 and 31b2.

[0094] [Number 7]

[0095]

[0096] Based on equations (6) and (7), the following equation is used to express the ratio R of the sum of the measured values ​​when the first optical element pair 31a composed of the first optical elements 31a1 and 31a2 is caused to emit light separately and the light is received by the second optical element 32, to the sum of the measured values ​​when the first optical element pair 31b composed of the first optical elements 31b1 and 31b2 is caused to emit light separately and the light is received by the second optical element 32.

[0097] [Number 8]

[0098]

[0099] Since the only unknown variable in equation (8) is z, the distance z to the object 50 can be calculated based on the ratio R.

[0100] Furthermore, for the first optical element pair 31 a , the following equation is obtained from equations (4) and (5).

[0101] [Number 9]

[0102]

[0103] The following equation is also obtained for the first optical element pair 31b.

[0104] [Number 10]

[0105]

[0106] The following equations are derived from equations (9) and (10).

[0107] [Number 11]

[0108]

[0109] Here, the parameter R is defined by equation (8), and the parameter A1 is defined by the following equation.

[0110] [Number 12]

[0111]

[0112] The value of parameter A1 can be calculated according to formula (11). If the value of parameter A1 is known, the tilt angle can be calculated according to formula (12) Furthermore, the tilt azimuth angle can be calculated according to formula (9): In this way, by obtaining the sum and difference of the measurement values ​​based on the two pairs of first optical elements 31a and 31b and performing simple algebraic calculations, the tilt angle can be calculated. and tilt azimuth

[0113] Next, the advantageous effects of the second embodiment will be described.

[0114] In the second embodiment, the distance z to the object 50 and the inclination angle of the surface of the object 50 can be obtained by performing simple algebraic operations without solving the four-variable simultaneous equations. and tilt azimuth

[0115] Next, an object detection sensor according to a modified example of the second embodiment will be described.

[0116] In the second embodiment, the four first optical elements 31 are light emitting elements and the one second optical element 32 is a light receiving element. However, the structure may be reversed such that one second optical element 32 is a light emitting element and the four first optical elements 31 are light receiving elements.

[0117] [Third embodiment]

[0118] Below, refer to Figure 8 A The object detection sensor of the third embodiment is described. Figure 7 The common structure of the object detection sensor of the second embodiment described above will be omitted.

[0119] Figure 8 A is a diagram showing the planar positional relationship between the first optical element 31 and the second optical element 32 of the object detection sensor of the third embodiment. Figure 7 ) includes one second optical element 32 and four first optical elements 31. In contrast, the object detection sensor of the third embodiment includes a plurality of first optical elements 31 and a plurality of second optical elements 32 arranged on the virtual plane 21. Figure 8 In A, the light receiving element is hatched.

[0120] Multiple second optical elements 32 are arranged at equal intervals along a straight line SL2. Multiple first optical elements 31 are arranged at equal intervals along each of two straight lines SL1 extending parallel to the straight line SL2, sandwiching the straight line SL2. The spacing between the multiple first optical elements 31 arranged on the straight line SL1 is equal to the spacing between the multiple second optical elements 32 arranged along the straight line SL2. The spacing between the straight lines SL1 and SL2 on one side is equal to the spacing between the straight lines SL1 and SL2 on the other side. Furthermore, a first optical element 31 is arranged at the intersection of a line passing through a second optical element 32 and a first optical element 31 on the straight line SL1 on one side, and the straight line SL1 on the other side.

[0121] This arrangement enables selection of two or more pairs of two first optical elements 31 arranged at mutually point-symmetrical positions about each second optical element 32. Of the two first optical elements 31 arranged at mutually point-symmetrical positions, one first optical element 31 is arranged on one straight line SL1, and the other first optical element 31 is arranged on the other straight line SL1. Two pairs of first optical elements, each consisting of a single second optical element 32 and two first optical elements 31 arranged at mutually point-symmetrical positions, are referred to as minimum units 30.

[0122] By using each of the plurality of minimum units 30, it is possible to compare with the second embodiment ( Figure 7 ) Similarly, the distance z to the object 50 and the inclination angle of the surface of the object 50 are obtained. and tilt azimuth

[0123] Next, the advantageous effects of the third embodiment will be described.

[0124] In the third embodiment, the distance z from each of the plurality of second optical elements 32 to the object 50 in the direction perpendicular to the virtual plane 21 along the straight line SL2 and the inclination angle of the surface of the object 50 can be obtained. and tilt azimuth Therefore, the spectrum profile of the surface of the object 50 in the direction parallel to the straight line SL2 can be obtained. and tilt azimuth The tilt angle of the surface of the object 50 with respect to the direction perpendicular to the straight line SL2 on the virtual plane 21 is obtained.

[0125] Furthermore, in the third embodiment, a single first optical element 31 is shared by multiple minimum units 30. Therefore, the number of first optical elements 31 can be reduced compared to a case where a first optical element 31 is not shared by multiple minimum units. Furthermore, in the third embodiment, no first optical element 31 is arranged between multiple second optical elements 32 arranged along the straight line SL2. Therefore, the second optical elements 32 can be densely arranged along the straight line SL2.

[0126] The four first optical elements 31 can be selected for the second optical element 32 so that the relative positional relationship between the one second optical element 32 and the four first optical elements 31 constituting the minimum unit 30 is the same in all the minimum units 30. When the relative positional relationship between the one second optical element 32 and the four first optical elements 31 is the same in all the minimum units 30, the variable r is used in the calculation of equations (8), (11), and (12) between the minimum units 30. a 、r b ,θ ra1 ,θ rb1 The respective values ​​are the same, so there is an excellent effect that calculation becomes easy.

[0127] Next, refer to Figure 8 B. An object detection sensor according to a modified example of the third embodiment will be described. Figure 8 B is a diagram showing the planar positional relationship between the first optical element 31 and the second optical element 32 of the object detection sensor according to a modified example of the third embodiment.

[0128] In the third embodiment ( Figure 8 In A), the intervals between the plurality of second optical elements 32 arranged along the straight line SL2 are the same as the intervals between the plurality of first optical elements 31 arranged along the straight lines SL1. Figure 8 In the modified example shown in FIG. 2B , the intervals between the plurality of first optical elements 31 arranged along each straight line SL1 are wider than the intervals between the plurality of second optical elements 32 arranged along the straight line SL2. In other words, the number of first optical elements 31 is smaller than that of the object detection sensor of the third embodiment.

[0129] Even if the intervals between the first optical elements 31 are wider than the intervals between the second optical elements 32, four first optical elements 31 constituting the minimum unit 30 can be selected for each of the plurality of second optical elements 32. Figure 8 In the modified example shown in B, Figure 8 Compared with the third embodiment shown in FIG. 1A, the number of first optical elements 31 can be further reduced. In addition, in the case of this modification, it is important to note that the variable r in equations (8), (11), and (12) is a 、rb ,θ ra1 ,θ rb1 The values ​​are no longer the same.

[0130] Next, other variations of the third embodiment will be described. In the third embodiment, the plurality of first optical elements 31 are arranged along two straight lines SL1. However, this arrangement is not necessarily required. It suffices to select four first optical elements 31 for each of the plurality of second optical elements 32 to form the minimum unit 30. Furthermore, to densely arrange the plurality of second optical elements 32, the first optical elements 31 are preferably arranged at positions offset from the straight line SL2.

[0131] In the third embodiment, the first optical element 31 uses a light emitting element and the second optical element 32 uses a light receiving element. However, conversely, the first optical element 31 may use a light receiving element and the second optical element 32 may use a light emitting element.

[0132] [Fourth embodiment]

[0133] Next, refer to Figure 9 The object detection sensor of the fourth embodiment is described. Figure 8 The common structure of the object detection sensor of the third embodiment described in A is omitted.

[0134] Figure 9 FIG. 1 is a diagram showing the planar positional relationship between the first optical element 31 and the second optical element 32 of the object detection sensor of the fourth embodiment. Figure 9 In the embodiment, the second light element 32 as the light receiving element is hatched. Figure 8 In Example A), the plurality of second optical elements 32 are arranged one-dimensionally along a straight line SL2 . In contrast, in the fourth embodiment, the plurality of second optical elements 32 are arranged two-dimensionally on the virtual plane 21 .

[0135] For example, a plurality of second optical elements 32 are disposed at the intersections of a plurality of straight lines SL2a arranged parallel to each other and at equal intervals, and a plurality of straight lines SL2b arranged parallel to each other and at equal intervals and intersecting the straight lines SL2a. In other words, the plurality of second optical elements 32 are arranged at equal intervals in a first direction parallel to the straight lines SL2a, and are also arranged at equal intervals in a second direction parallel to the straight lines SL2b.

[0136] A plurality of first optical elements 31 are disposed at the intersections of a plurality of equally spaced straight lines SL1a, which are parallel to straight line SL2a, and a plurality of equally spaced straight lines SL1b, which are parallel to straight line SL2b. Specifically, the plurality of first optical elements 31 are arranged at equal intervals in a first direction parallel to straight line SL1a and also at equal intervals in a second direction parallel to straight line SL1b. Straight line SL1a is disposed at the center of two adjacent straight lines SL2a, and straight line SL1b is disposed at the center of two adjacent straight lines SL2b.

[0137] The four first optical elements 31 constituting the minimum unit 30 can be selected for each of the plurality of second optical elements 32. Furthermore, the four first optical elements 31 can be selected so that the positional relationship between the second optical elements 32 and the four first optical elements 31 is the same across the plurality of minimum units 30.

[0138] Next, the excellent effects of the fourth embodiment will be described.

[0139] In the fourth embodiment, the spectral profile of the surface of the object 50 along each of the plurality of straight lines SL2a and the spectral profile of the surface of the object 50 along each of the plurality of straight lines SL2b can be determined. Furthermore, in the fourth embodiment, no first optical element 31 is disposed between two second optical elements 32 arranged parallel to the straight line SL2a or between two second optical elements 32 arranged parallel to the straight line SL2b. This allows for a dense, two-dimensional arrangement of the plurality of second optical elements 32 (measurement points).

[0140] One first optical element 31 is shared by a plurality of minimum units 30. Therefore, the number of first optical elements 31 can be reduced.

[0141] Next, an object detection sensor according to a modified example of the fourth embodiment will be described.

[0142] In the fourth embodiment, the plurality of second optical elements 32 are arranged at equal intervals along the straight line SL2a and at equal intervals along the straight line SL2b. However, the plurality of second optical elements 32 need not necessarily be arranged along a straight line. It is sufficient to arrange the plurality of second optical elements 32 two-dimensionally, and to arrange four first optical elements 31 constituting the minimum unit 30 for each second optical element 32. In this case, it is preferable to arrange the plurality of minimum units 30 so that one first optical element 31 is shared by the plurality of the first optical elements 31.

[0143] [Fifth embodiment]

[0144] Next, refer to Figure 10 、 Figure 11 as well as Figure 12The object detection sensor of the fifth embodiment is described. Figure 9 The common structure of the object detection sensor of the fourth embodiment described above will be omitted.

[0145] Figure 10 : is a schematic top view showing the positional relationship between a plurality of first optical elements 31 and a second optical element 32 included in one of a plurality of minimum units 30 of the object detection sensor of the fifth embodiment. Figure 9 ), the minimum unit 30 is composed of one second optical element 32 and two groups of first optical element pairs (four first optical elements 31). In contrast, in the fifth embodiment, each minimum unit 30 includes one second optical element 32 and three or more groups of first optical element pairs (six or more first optical elements 31). Figure 10 In the embodiment, a minimum unit 30 is shown to include five first optical element pairs 31a, 31b, 31c, 31d, and 31e. Figure 9 ), ten first optical elements 31 can be selected for each of the plurality of second optical elements 32 in such a manner that one minimum unit 30 includes five pairs of first optical elements.

[0146] The distances from the first optical element 31 to the second optical element 32 of each of the first optical element pairs 31a, 31b, 31c, 31d, and 31e are marked as r. a 、r b 、r c 、r d 、r e . Distance r a 、r b 、r c 、r d 、r e The size relationship is as follows.

[0147] [Number 13]

[0148] r a <r b <r c <r d <r e …(13)

[0149] As an example, r a =5mm, r b =7.5mm, r c =10mm, r d =15mm, r e =20mm.

[0150] Figure 11This is a graph showing the relationship between the ratio R (Equation (8)) and the distance z when two pairs of first optical elements and one second optical element 32 are in operation. The horizontal axis represents the distance z in [mm], and the vertical axis represents the ratio R. The distance from the first optical element 31 to the second optical element 32 of the two pairs of first optical elements in operation is marked as r. S 、r L Here, r S <r L . Figure 11 The thin dotted line, thick dotted line, thin solid line and thick solid line in the graph respectively represent r L =7.5mm, r L =10mm, r L =15mm and r L = 20mm. In any case, the ratio R is S =5mm.

[0151] It can be seen that the ratio R increases as the distance z increases. L The shorter the distance z, the faster the ratio R becomes larger. In order to improve the measurement accuracy of the distance z, it is preferred to use the area with a large slope of the curve to calculate the distance z. That is, if the distance z becomes longer, it is preferred to make the distance r L The first optical element with the longest length operates with a ratio R. Figure 11 In the example shown, when the distance z is within the range of each of the intervals Z1, Z2, Z3, and Z4, it is preferable to make the distance r L The first optical element pairs with the distances of 7.5mm, 10mm, 15mm and 20mm are operated. S The first optical element pair with a diameter of 5 mm operates.

[0152] Figure 12 The calculation unit 40 ( Figure 1 A) Flowchart of the executed process. The calculation unit 40 first calculates the distance r L Set to 20 mm (step SB1). That is, the distance r S =5mm first optical element pair 31a and distance r L =20mm first optical element pair 31e is operated. The two sets of first optical element pairs 31a and 31e are operated separately to measure the brightness La1, La2, Lb1, and Lb2 of formula (8). The brightness La1 and La2 are obtained by making the distance r S = 5mm, the two first optical elements 31 of the first optical element pair 31a are operated and measured. The brightness Lb1 and Lb2 are measured by making the distance r L=20 mm is measured by operating the two first optical elements 31 of the first optical element pair 31e. Based on this measurement result, a provisional value of the distance z is calculated using equation (8) (step SB2).

[0153] Next, the processing corresponding to the tentative value of distance z is executed (step SB3). Figure 11 When the range of interval Z1 is shown, r L Set to 7.5mm (step SB4). Figure 11 When the range of interval Z2 is shown, r L Set to 10mm (step SB5). Figure 11 When the range of interval Z3 is shown, r L Set to 15mm (step SB6). Figure 11 If it is within the range of the indicated interval Z4, the provisional value of the distance z is adopted as the measurement result (step SB8).

[0154] The distance r is reset in step SB4, SB5 or SB6. L Then, make the distance r L The first optical element pair is operated and the provisional value of the distance z is recalculated (step SB7). In addition, the distance r is also set at this time. S Keep 5mm.

[0155] Determine whether the recalculated distance z is within Figure 11 The intervals Z1, Z2, Z3, and Z4 shown are related to the distance r L The recalculated distance z is not within the range corresponding to the set value of the distance r (step SB8). L If the recalculated distance z is within the range corresponding to the set value of the distance r, the process from step SB3 is repeated. L If the distance z is within the range corresponding to the set value, the recalculated provisional value of the distance z is adopted as the measurement result (step SB9).

[0156] Thus, in the fifth embodiment, the first optical element 31 and the second optical element 32 of two selected first optical element pairs from a plurality of first optical element pairs are first activated, and a provisional value of the distance z is calculated (step SB2). Based on the provisional value, two selected first optical element pairs are then selected from the plurality of first optical element pairs (steps SB4, SB5, and SB6). The first optical element 31 and the second optical element 32 of the selected two first optical element pairs are then activated, and the provisional value of the distance z is recalculated (step SB7). In this way, based on the provisional value of the distance z, the two preferred first optical element pairs are activated, and the distance z is calculated.

[0157] Next, the advantageous effects of the fifth embodiment will be described.

[0158] In the fifth embodiment, for a plurality of minimum units 30 ( Figure 9 、 Figure 10 ) in each minimum unit 30, the first optical element pair that best matches the value of the distance z is operated and measured. Therefore, the measurement accuracy of the distance z can be improved.

[0159] Next, an object detection sensor according to a modified example of the fifth embodiment will be described.

[0160] In the fifth embodiment, each minimum unit 30 includes five pairs of first optical elements 31a, 31b, 31c, 31d, and 31e, but the minimum unit 30 may include three or more pairs of first optical elements. Figure 11 In this case, in step SB3 ( Figure 12 ), the process is divided into two branches. If the tentative value of distance z is within the range of the preferred interval, the tentative value is adopted as the measurement result (equivalent to step SB9). If the tentative value of distance z is outside the range of the preferred interval, the distance r is selected. L A different first optical element pair is used, and the provisional value of the distance z is recalculated (equivalent to step SB7).

[0161] In the fifth embodiment, in step SB1 ( Figure 12 ), the distance r L The longest value is set to 20 mm. This is because it is assumed that the following situations are common: the object 50 ( Figure 1 A), then, the object 50 approaches the object detection sensor. In addition, in the case where the range of distance z at which the object 50 is initially detected is pre-conceived, in step SB1 ( Figure 12 ), it is preferred to set the distance r L Set to a value corresponding to the assumed distance z.

[0162] The above embodiments are merely illustrative. It goes without saying that the structures shown in different embodiments can be partially replaced or combined. The same effects achieved by the same structure in multiple embodiments are not mentioned individually in each embodiment. Furthermore, the present invention is not limited to the above embodiments. For example, it will be apparent to those skilled in the art that various modifications, improvements, and combinations are possible.

[0163] Description of Reference Numerals

[0164] 20: substrate; 21: virtual plane; 25: reference axis; 30: minimum unit; 31, 31a1, 31a2, 31b1, 31b2, 31i: first optical element; 31a, 31b, 31c, 31d, 31e: first optical element pair; 32: second optical element; 40: operation unit; 50: object.

Claims

1. An object detection sensor comprising: at least four first optical elements arranged on the virtual plane; at least one second optical element disposed on the virtual plane; and Operation unit, in, One of the first optical element and the second optical element is a light emitting element, and the other is a light receiving element. A minimum unit is formed by at least four of the first optical elements and one of the second optical elements, The four first optical elements of the minimum unit have the same directional characteristics. Regarding the directional characteristics of the second optical element, when a straight line extending from the second optical element along the normal direction of the virtual plane is used as a reference axis, the inclination angle at which the illuminance or light sensitivity in a direction inclined relative to the reference axis is 1 / 2 of the illuminance or light sensitivity in the direction of the reference axis is 15° or less. The four first optical elements of the minimum unit are not arranged on a common straight line passing through the second optical element, nor are they arranged on a common circumference centered on the second optical element. The calculation unit calculates the distance from the virtual plane to the object on the reference axis, the inclination angle of the normal direction of the surface of the object relative to the reference axis, and the inclination azimuth angle based on the measured value of the light intensity when the first light element and the second light element, which are the minimum units, are operated.

2. The object detection sensor according to claim 1, wherein: The minimum unit includes at least two pairs of first optical elements, each of which is composed of two first optical elements arranged at positions point-symmetrical to each other with respect to the second optical element.

3. The object detection sensor according to claim 2, wherein: The calculation unit calculates the distance from the virtual plane to the object based on the sum of the measured values ​​when the first optical element and the second optical element of the first optical element pair on one side are operated and the sum of the measured values ​​when the first optical element and the second optical element of the other side of the first optical element pair are operated.

4. The object detection sensor according to claim 3, wherein: The minimum unit includes at least three groups of the first optical element pairs, The calculation unit operates the first optical elements and the second optical elements of two selected first optical element pairs from the three first optical element pairs, and obtains a provisional value of the distance from the virtual plane to the object. The calculation unit selects two groups of the first optical element pairs from at least three groups of the first optical element pairs based on the provisional value, and calculates the distance from the virtual plane to the object based on the measured values ​​when the first optical elements and the second optical elements of the two selected groups of the first optical element pairs are operated.

5. The object detection sensor according to any one of claims 2 to 4, wherein: The calculation unit calculates the inclination angle of the normal direction of the surface of the object relative to the reference axis and the inclination azimuth angle based on the difference between the measured values ​​when the first optical element and the second optical element of the first optical element pair on one side are operated and the difference between the measured values ​​when the first optical element and the second optical element of the first optical element pair on the other side are operated.

6. The object detection sensor according to any one of claims 2 to 5, wherein: A plurality of the second optical elements are configured, For each of the plurality of second optical elements, a plurality of first optical elements are arranged so as to constitute the minimum unit. At least one of the plurality of first optical elements is shared by at least two of the minimum units.

7. The object detection sensor according to claim 6, wherein: The plurality of second optical elements are arranged in a straight line.

8. The object detection sensor according to claim 6, wherein: The plurality of second optical elements are arranged at equal intervals in a first direction and are also arranged at equal intervals in a second direction intersecting the first direction. The plurality of first optical elements are arranged at equal intervals in the first direction and are also arranged at equal intervals in the second direction. The arrangement interval of the plurality of first optical elements in the first direction is equal to the arrangement interval of the plurality of second optical elements in the first direction. The arrangement interval of the plurality of first optical elements in the second direction is equal to the arrangement interval of the plurality of second optical elements in the second direction.

9. An object detection method, wherein the first optical element and the second optical element, which are the minimum units composed of each first optical element and the second optical element of at least four first optical elements arranged on a common virtual plane, are operated to detect an object on a reference axis extending from the second optical element in the normal direction of the virtual plane, wherein: One of the first optical element and the second optical element is a light emitting element, and the other is a light receiving element. The four first optical elements of the minimum unit have the same directional characteristics, and the directional characteristics of the second optical element have an inclination angle of 15° or less when the illuminance or light sensitivity in a direction inclined relative to the reference axis is 1 / 2 of the illuminance or light sensitivity in the direction of the reference axis. The four first optical elements of the minimum unit are not arranged on a common straight line passing through the second optical element, nor are they arranged on a common circumference centered on the second optical element. A brightness measurement value when the object is used as a new light source is obtained based on light emitted from one of the first and second optical elements of the minimum unit, reflected by the object, and received by the other element. Based on the measured value, at least one of the reflectivity of the surface of the object, the distance from the virtual plane to the object on the reference axis, the tilt angle of the surface of the object relative to the reference axis, and the tilt azimuth angle of the surface of the object is calculated.

10. The object detection method according to claim 9, wherein: The minimum unit includes at least two pairs of first optical elements, each of which is composed of two first optical elements arranged at positions point-symmetrical with respect to the second optical element. calculating a sum of the measurement values ​​obtained by operating the first optical element and the second optical element of one of the first optical element pairs and a sum of the measurement values ​​obtained by operating the first optical element and the second optical element of the other of the first optical element pairs, The distance from the virtual plane to the object on the reference axis is calculated based on the sum of the measurement values.

11. The object detection method according to claim 10, wherein: calculating a difference between the measurement values ​​obtained by operating the first optical element and the second optical element of one of the first optical element pairs and a difference between the measurement values ​​obtained by operating the first optical element and the second optical element of the other of the first optical element pairs, At least one of a tilt angle of the surface of the object with respect to the reference axis and a tilt azimuth angle of the surface of the object is calculated based on the difference between the measurement values.

12. The object detection method according to claim 10 or 11, wherein: The minimum unit includes at least three groups of the first optical element pairs, operating the first optical elements and the second optical elements of two selected first optical element pairs from the three first optical element pairs, and obtaining a provisional value of the distance from the virtual plane to the object; Based on the provisional value, two first optical element pairs are selected from at least three first optical element pairs, the first optical elements and the second optical elements of the selected two first optical element pairs are operated, and the distance from the virtual plane to the object is calculated.

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