Optical distance measuring device and method

Abstract

To accurately measure the distance to an object.SOLUTION: An optical distance measuring device 10 measures distance to an object 4. The optical distance measuring device includes a light output section 11 that emits reference light 1, a light scanning section 12 that emits measurement light 2, and a light receiving section 13 that receives reflected light 3 of the measurement light 2 and the reference light 1 from the object 4. The optical distance measuring device scans a focal point of the measurement light 2 on a surface of the object 4 and calculates the distance by an angle of the light scanning section 12 when the focal point of the measurement light matches a focal point of the reference light 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical distance measuring device and method for optically measuring the distance to an object. [Background technology]

[0002] Known optical distance measuring devices that optically measure the distance to an object use phase difference, TOF (Time Of Flight), and triangulation as their measurement principles. As shown in Fig. 11(a), an example 30 of an optical distance measuring device using triangulation includes a light emitting element 31, a light receiving element 33, a light emitting lens 32, and a light receiving lens 34, and irradiates light 301 onto an object 4, receives reflected light 302, and measures the distance to the object 4 (for example, Patent Document 1).

[0003] In the optical system of the triangulation distance measuring method, as shown in Fig. 11(a), light 301 from a light source 31 is transmitted through a light emitting lens 32 and irradiated onto an object 4. Light 302 reflected by the object 4 is collected by a light receiving lens 34 and forms an image on a light receiving element 33.

[0004] When reflected light 302 from the object 4 is incident on the light receiving element 33 at an angle θ, the distance D0 between the light source 31 and the object 4 is calculated by equation (1), where L is the distance between the light source 31 and the image formation position.

[0005] D0 = L0 tan θ (1)

[0006] For example, as shown in FIG. 11(a), when the object 4 is at the position Z1, D01=L01·tan θ01.

[0007] In this optical system, when the object 4 moves on the optical axis connecting the light source 31 and the object 4 (for example, from position Z1 to position Z2), the distance D0 between the light source 31 and the object 4 can be calculated using formula (1). For example, when the object 4 is at position Z2, D02 = L02 tan θ02.

[0008] For example, an optical distance measuring device is used in a level meter to measure the change in height from height D01 of the liquid level Z1 in a liquid tank to height D02 of the liquid level Z2. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2012-37276 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, it is difficult to set the optical axis connecting the light source 31 and the object 4 completely parallel to the perpendicular direction to the surface of the object 4. As shown in Fig. 11(b), when the optical axis connecting the light source 31 and the object 4 has an arbitrary angle θx with the perpendicular direction to the surface of the object 4, the relationship of formula (1) does not hold.

[0011] As a result, if the value of the angle θx cannot be obtained accurately, the distance D01 between the light source 31 and the object 4 cannot be calculated using equation (1), making it difficult to measure the distance to the object 4 accurately.

[0012] Furthermore, when the object 4 moves in a direction other than the optical axis connecting the light source 31 and the object 4, as shown in FIG. 11(b), it is difficult to accurately measure the distance D02 to the object 4. [Means for solving the problem]

[0013] In order to solve the problems described above, the optical distance measuring device of the present invention is an optical distance measuring device that measures the distance to an object, and is equipped with an optical output unit that emits reference light, an optical scanning unit that emits measurement light, and a light receiving unit that receives reflected light of the measurement light and the reference light from the object, and is characterized in that the focus of the measurement light is scanned over the surface of the object, and the distance is calculated from the scanning angle of the optical scanning unit when it coincides with the focus of the reference light.

[0014] In the optical distance measuring device according to the present invention, the optical paths along which the measurement light and the reference light are irradiated onto an object may be on the same plane.

[0015] In addition, the optical distance measuring device of the present invention may be configured so that the light output unit has a light source and a light branching unit, the light branching unit branches the light from the light source into a first light and a second light, the light scanning unit reflects the second light at a light reflecting unit and irradiates the object as the measurement light, and the first light is irradiated onto the object as the reference light.

[0016] In the optical distance measuring device according to the present invention, the optical scanning section may have another light source.

[0017] In the optical distance measuring device according to the present invention, the light receiving section may have an angle measuring sensor.

[0018] In the optical distance measuring device according to the present invention, the scanning drive section of the optical scanning section may be a one-axis driving type MEMS.

[0019] In addition, an optical distance measuring method of the present invention is an optical distance measuring method for measuring a distance to an object, and includes the steps of irradiating a measurement light onto the object, irradiating a reference light onto the object, receiving reflected light of the measurement light and the reference light from the object, scanning the measurement light on the surface of the object and detecting a scanning angle of the measurement light when the focus of the measurement light coincides with the focus of the reference light, and calculating the distance from the scanning angle of the measurement light.

[0020] In the optical distance measuring method according to the present invention, the distance may be calculated by formula (A).

[0021] D = L tan θ (A)

[0022] Here, D is the distance, L is the distance between the emission position of the measurement light and the emission position of the reference light, and θ is the scan angle.

[0023] In the optical distance measuring method according to the present invention, the corrected distance may be calculated by equation (B).

[0024] d = D cos(|α-β| / 2) (B)

[0025] Here, d is the distance to be corrected, α is the scanning angle of the measurement light, and β is the light receiving angle at which the received light intensity of the reflected light is maximized. Effect of the Invention

[0026] According to the present invention, it is possible to provide an optical distance measuring device and method capable of accurately measuring the distance to an object. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a block diagram showing the configuration of an optical distance measuring device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an example of an optical system of the optical distance measuring device according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing an example of the optical scanning unit in the optical distance measuring device according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a flow chart showing the optical distance measuring method according to the first embodiment of the present invention. [Diagram 5] FIG. 5 is a diagram for explaining the effects of the optical distance measuring device and method according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing an example of an optical system of an optical distance measuring device according to a modified example of the first embodiment of the present invention. [Figure 7] FIG. 7 is a schematic diagram showing an example of an optical system of an optical distance measuring device according to a second modification of the first embodiment of the present invention. [Figure 8] FIG. 8 is a block diagram showing a configuration of an optical distance measuring device according to the second embodiment of the present invention. [Figure 9]FIG. 9 is a schematic diagram showing an example of an optical system of an optical distance measuring device according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing an example of an optical system of an optical distance measuring device according to a modified example of the second embodiment of the present invention. [Figure 11] FIG. 11 is a schematic diagram showing an example of an optical system of a conventional optical distance measuring device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] <First embodiment> An optical distance measuring device 10 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.

[0029] <Configuration of optical distance measuring device> 1, an optical distance measuring device 10 according to this embodiment includes a light output unit 11, a light scanning unit 12, a light receiving unit 13, and a control unit 14. Here, the light output unit 11 includes a light source 111 and a light branching unit 112. In addition, the light scanning unit 12 includes a scan driving unit 122 and a light reflecting unit 121.

[0030] The control unit 14 includes a light source drive power supply 141 that drives the light source 111 , an optical scanning control unit 142 that controls the scan drive unit 122 of the optical scanning unit 12 , and an analysis unit 143 .

[0031] The analysis unit 143 is connected to the light receiving unit 13 and the optical scanning control unit 142, and calculates the distance to the target object (described later).

[0032] 2 shows the optical system of the optical distance measuring device 10. The optical distance measuring device 10 uses a semiconductor laser 111 as a light source, a half mirror 112 as a light branching section, and a CMOS image sensor 13 as a light receiving section. Also, a MEMS (Micro Electro Mechanical Systems) 122 is used as a scanning drive section of the optical scanning section, and a mirror 121 is used as a light reflecting section, that is, a so-called MEMS mirror 12.

[0033] Light emitted from the semiconductor laser 111 is incident on the half mirror 112 and branched into a first light 1 and a second light 1_2. The first light is emitted as reference light 1 from a light branching section (half mirror) 112 in the light output section 11, and is irradiated onto a surface of an object to be measured (hereinafter referred to as an "object") 4 on an extension line of the optical axis of the half mirror 112 from the semiconductor laser 111. Here, the position where the reference light 1 is emitted from the half mirror 112 is the emission position of the light output section 11, in other words, the emission position of the reference light 1.

[0034] The second light 1_2 is reflected by the MEMS mirror 12 and then irradiated onto the object 4 as the measurement light 2. Here, the position where the measurement light 2 is reflected by the MEMS mirror 12 and emitted is the emission position of the measurement light 2.

[0035] In this way, the optical axis direction of the reference light 1 is fixed, and the optical axis direction of the measurement light 2 changes over time by driving the MEMS mirror 12. Here, the measurement light 2 is not in a twisted relationship with the reference light 1, and always intersects with it unless it is parallel. In other words, the optical path of the measurement light 2 irradiated to the object 4 and the optical path of the reference light 1 are on the same plane.

[0036] Each light is diffusely reflected by the object 4, and a part of it is received by the CMOS image sensor 13. Therefore, the CMOS image sensor 13 observes the points where the measurement light 2 and the reference light 1 respectively irradiate the object 4 as bright points.

[0037] 3, the MEMS 122 is a one-axis drive type MEMS, and includes a fixed frame 123 that supports a movable part 124 formed to be rotatable about a first axis 120. A mirror 121, which is a light reflecting part, is mounted on the movable part 124.

[0038] Also, a first magnet (N pole) 128_1 and a second magnet (S pole) 128_2 are arranged on both sides of the fixed frame 123, respectively, for forming a uniform magnetic field in a direction perpendicular to the first axis 120. For example, the N pole of the first magnet (N pole) 128_1 is arranged facing the fixed frame 123, and the S pole of the second magnet (S pole) 128_2 is arranged facing the fixed frame 123. The first magnet (N pole) 128_1 and the second magnet (S pole) 128_2 can be formed of, for example, a permanent magnet or an electromagnet.

[0039] The movable portion 124 is connected to the inside of the fixed frame 123 via first beams 125 formed on both sides of the movable portion 124 in the direction of the first axis 120 .

[0040] Further, a driving coil 126 for rotating the movable part 124 about the first shaft 120 as a central axis is disposed in the movable part 124. For example, the driving coil 126 is configured by being wound so as to make a plurality of turns within the plane of the movable part 124, and one end of the driving coil 126 is connected to a first electrode 127_1 of the fixed frame 123 via a first beam 125, and the other end of the driving coil 126 is connected to a second electrode 127_2 of the fixed frame 123 via the first beam 125.

[0041] A signal for driving the movable part 124 is applied to the driving coil 126. When a signal is applied to the driving coil 126, a Lorentz force generated by a magnetic field formed by the first magnet (N pole) 128_1 and the second magnet (S pole) 128_2 and a current flowing through the driving coil 126 drives the movable part 124.

[0042] Here, the movable portion 124 and the first beam 125 are each designed to have a mass and elastic rigidity suitable for the frequency vibration of the signal.

[0043] In this way, the movable part 124 rotates about the first shaft 120. As a result, the mirror 121 mounted on the movable part 124 rotates, and the light reflected by the mirror 121 scans the object 4.

[0044] <Optical ranging method> The optical distance measuring method according to this embodiment will be described with reference to Fig. 4. Fig. 4 is a flow chart showing the optical distance measuring method.

[0045] First, in the optical distance measuring device 10, the measurement light 2 and the reference light 1 are irradiated onto the object 4 (step 151). When each light beam is irradiated onto a different position on the object 4 (not in focus), multiple bright spots are observed on the CMOS image sensor 13.

[0046] Next, the optical scanning unit 12 (scan driving unit 122) is driven to scan the measurement light 2 on the surface of the object 4 (step 152).

[0047] Next, the focal point of the measurement light 2 is aligned with the focal point of the reference light 1 on the surface of the object 4 (step 153). As a result, a point where a brighter bright spot is observed on the CMOS imaging element 13 is detected. At this time, the reference light 1 and the measurement light 2 are in focus on the surface of the object 4. Arrow 3 in FIG. 2 indicates the reflected light of the reference light 1 and the measurement light 2 on the object in the focused state.

[0048] For example, the in-focus state can be detected when the intensity of the light received by the CMOS imaging element 13 is at a maximum. Alternatively, the in-focus state may be observed visually.

[0049] Next, the scan angle θ of the optical scanning unit 12 in this focused state is detected. Here, the scan angle θ of the optical scanning unit is an angle between the incident direction of the light (second light) 1_2 and the reflection direction (the emission direction of the measurement light 2) with respect to the surface of the MEMS mirror 12, and is also called the "scan angle of the measurement light."

[0050] When detecting the scanning angle θ of the optical scanning unit 12, the optical scanning unit 12 may be oscillated at a predetermined speed to detect the moment when the in-focus state is reached, or the optical scanning unit 12 may be stopped in the in-focus state to detect the scanning angle.

[0051] Alternatively, the CMOS imaging element 13 may measure the distance between the focal position determined by the measurement light 2 and the focal position determined by the reference light 1, and feed this distance back to the optical scanning unit 12 so that it becomes zero or a predetermined value or less, thereby detecting the scanning angle θ of the optical scanning unit 12 with the state where the distance is zero or a predetermined value or less being the in-focus state.

[0052] Finally, the distance D from the emission position of the light output unit 11 (the emission position of the half mirror 112) to the object 4 is calculated using equation (2). Here, the distance between the emission position of the measurement light 2 and the emission position of the reference light 1 is represented as L.

[0053] D = L tan θ (2)

[0054] Here, light of different wavelengths may be used for the measurement light 2 and the reference light 1, and the in-focus state may be detected as a composite color of the respective lights. For example, when red light is used for the measurement light 2 and blue light is used for the reference light 1, the in-focus state is detected as purple, which is the composite color of the respective lights. This can improve the accuracy of visual measurement (S / N ratio).

[0055] <Effects> As described above, according to the optical distance measuring device and method of the present embodiment, the distance to the object 4 can be measured accurately.

[0056] In particular, as described below, even if the direction of light irradiation from the light output unit 11 to the object 4 has an arbitrary angle from the perpendicular direction to the surface of the object 4, the distance to the object 4 can be accurately measured.

[0057] 5(a), the reference light 1 is irradiated to the object 4 at an arbitrary angle θx1. When the reference light 1 forms a focal point P1 on the surface of the object 4, the optical scanning unit 12 is driven to scan the focal point of the measurement light 2 on the surface of the object 4, and the scanning angle θ1 of the optical scanning unit 12 at which the focal points of the measurement light 2 and the reference light 1 coincide with each other is detected.

[0058] Let L be the distance between the optical scanning unit 12 and the half mirror 112, i.e., the distance between the emission position of the measurement light 2 and the emission position of the reference light 1. Using equation (2), the distance D1 from the emission position of the optical output unit 11 (the emission position of the half mirror 112) in the direction parallel to the reference light 1 to the object 4 can be calculated.

[0059] Furthermore, when the irradiation direction of the reference light 1 (light from the light source 111) and the direction in which the object 4 moves form an arbitrary angle, the change in the distance to the object 4 can be measured accurately.

[0060] 5(b), when the object 4 moves from position Z1 to position Z2, the reference light 1 is irradiated onto the object 4 at an arbitrary angle θx2. When the reference light 1 forms a focus P2 on the surface of the object 4, the optical scanning unit 12 is driven to scan the focus of the measurement light 2 on the surface of the object 4, and the scanning angle θ2 of the optical scanning unit 12 at which the focus of the measurement light 2 and the focus of the reference light 1 coincide is detected.

[0061] Let L be the distance between the optical scanning unit 12 and the half mirror 112, i.e., the distance between the emission position of the measurement light 2 and the emission position of the reference light 1. Using equation (2), the distance D2 from the emission position of the optical output unit 11 (the emission position of the half mirror 112) in the direction parallel to the reference light 1 to the object 4 can be calculated.

[0062] In the optical distance measuring device and method of this embodiment, measurement light 2 and reference light 1 are used, the optical axis of reference light 1 is fixed and set as a fixed axis, and the optical axis of measurement light 2 is changed to detect the angle with the fixed axis.

[0063] As a result, even if the irradiation direction from light output unit 11 and the direction in which object 4 moves form an arbitrary angle, it is possible to accurately measure the distance from light output unit 11 to object 4 in a direction parallel to reference light 1. In this way, the change in the relative distance from light output unit 11 to object 4 can be accurately measured.

[0064] <Variation 1> An optical distance measuring device and method according to a first modified example of the present embodiment will be described with reference to FIGS. 6(a) and 6(b).

[0065] As described above, in the first embodiment, the distance D from the emission position of the light output unit 11 (the emission position of the half mirror 112) in the direction parallel to the reference light 1 to the object 4 can be calculated, but the distance (absolute value of the distance) from the half mirror 112 to the object 4 in the perpendicular direction to the object 4 cannot be obtained.

[0066] In this modification, the distance (absolute value of the distance) from the half mirror 112 to the object 4 in the perpendicular direction to the object 4 can be calculated based on the distance D from the emission position of the light output unit 11 (the emission position of the half mirror 112) in the direction parallel to the reference light 1 to the object 4. Details will be described below.

[0067] Similarly to the first embodiment, the optical distance measuring device 10_2 according to this modification includes a light output unit 11, a light scanning unit, a light receiving unit 13, and a control unit 14. Here, the light output unit 11 has a light source 111 and a light branching unit 112.

[0068] 6(a) and (b) show the optical system of the optical distance measuring device 10_2. The optical distance measuring device 10_2 uses a semiconductor laser 111 as a light source, a half mirror 112 as a light branching unit, a MEMS mirror 12 as a light scanning unit, and a CMOS image sensor 13 as a light receiving unit. Furthermore, the light receiving unit 13 has an angle measuring sensor (angle measuring sensor).

[0069] The light emitted from the semiconductor laser 111 is incident on the half mirror 112 and, as in the first embodiment, is split into reference light 1 and measurement light 2, with the reference light 1 being directly irradiated onto the object 4 and the measurement light 2 being reflected by the MEMS mirror 12 and irradiated onto the object 4.

[0070] As shown in Figure 6(a), when the reference light 1 is incident perpendicularly on the object 4 and is in focus at a scanning angle of the optical scanning unit 12 (scanning angle of the measurement light 2) α, the incident angle of the measurement light 2 on the object 4 is π / 2-α, and of the measurement light diffusely reflected by the object 4, light 3 reflected at a reflection angle π / 2-α is received by the light receiving unit 13 with maximum intensity.

[0071] At this time, the angle β (hereinafter referred to as the "light receiving angle") formed between the incident direction of the reflected light 3 of the measurement light 2 (and the reference light 1) to the light receiving unit 13 and the parallel direction to the line connecting the exit position of the light output unit 11 (light branching unit) and the exit position of the light scanning unit 12 is α.

[0072] 6(b), when the reference light 1 is incident at an arbitrary angle θ in the vertical direction of the object 4 and is in focus at a scanning angle α of the optical scanning unit 12, the incident angle of the measurement light 2 to the object 4 becomes π / 2-α+θ, and of the measurement light diffusely reflected by the object 4, light 3 reflected at a reflection angle π / 2-α+θ is received with maximum intensity by the light receiving unit 13. In this case, the incident angle β of the reflected light 3 of the measurement light 2 (and reference light 1) to the light receiving unit 13 is α-2θ.

[0073] In this way, when the reference light 1 is incident at an arbitrary angle θ in the vertical direction of the object 4, the incident angle β of the reflected light 3 of the measurement light 2 (and reference light 1) to the light receiving unit 13 in the focused state is α-2θ, and the change |α-β| is 2θ. Therefore, the angle θ between the incident direction of the reference light 1 and the vertical direction of the object 4 is calculated from θ=|α-β| / 2.

[0074] Therefore, the distance d from the emission position of the light output unit 11 to the object 4 in the vertical direction of the object 4 is calculated by equation (3) using the distance D calculated by equation (2) (the distance from the emission position of the light output unit 11 to the object 4 in the direction parallel to the reference light 1).

[0075] d = D cosθ (3)

[0076] In this way, according to the optical distance measuring device and method of this modified example, the distance D to the object 4 in the direction parallel to the reference light 1 can be corrected, and the distance d (absolute value of the distance) from the emission position of the light output unit 11 to the object 4 in the vertical direction of the object 4 can be calculated.

[0077] <Variation 2> An optical distance measuring device and method according to a second modification of the present embodiment will be described with reference to Figs. 7(a) and (b). In Fig. 7(a), in order to easily explain this modification, only the path of the reference light irradiated onto the object is shown.

[0078] In this modified example, as shown in FIG. 7(a), calculation of the distance d (absolute value of the distance) to the object 4 in the vertical direction is described when the reference light 1 is incident on the object 4 not only in the x direction in the figure but also at an arbitrary angle in the y direction in the figure.

[0079] Similarly to the first embodiment, the optical distance measuring device 10_3 according to this modification includes a light output unit 11, a light scanning unit, a light receiving unit 13, and a control unit 14. Here, the light output unit 11 has a light source 111 and a light branching unit 112.

[0080] Fig. 7(b) shows the optical system of the optical distance measuring device 10_3. The optical distance measuring device 10_3 uses a semiconductor laser (first semiconductor laser) 111 as a light source, a half mirror 112 as a light branching unit, a MEMS as the first optical scanning unit 12_1, a MEMS mirror 12_2 as the second optical scanning unit, and a CMOS image sensor as the light receiving unit 13. Furthermore, the first optical scanning unit 12_1 includes a semiconductor laser as an auxiliary light source. Also, the light receiving unit 13 includes an angle measurement sensor (angle measurement sensor).

[0081] Here, the first optical scanning unit 12_1 is disposed at a predetermined angle (90° in this modified example) and a distance L1 with respect to the direction from the optical branching unit 112 to the second optical scanning unit 12_2.

[0082] As in the first modification of the first embodiment, the light emitted from the semiconductor laser 111 is split by the half mirror 112, the reference light 1 is directly irradiated onto the object 4, and the measurement light (second measurement light) 2_2 is reflected by the MEMS mirror 12_2 and irradiated onto the object 4. In a state in which the reference light 1 and the measurement light 2_2 are in focus, the reflected light from the object 4 is received by the light receiving unit 13, and θ1 shown in FIG. 7(a) is calculated.

[0083] In addition, in the first optical scanning unit 12_1, light emitted from an auxiliary light source (semiconductor laser) is irradiated onto the object 4 as a measurement light (first measurement light) 2_1 and scanned by the MEMS. From the resulting focused state of the reference light 1 and the measurement light 2_1, θ2 shown in FIG. 7(a) is calculated.

[0084] Therefore, the distance d from the emission position of the light output unit 11 to the object 4 in the vertical direction of the object 4 is calculated by equation (4) using the distance D calculated by equation (2) (the distance from the emission position of the light output unit 11 to the object 4 in the direction parallel to the reference light 1) and angles θ1 and θ2.

[0085] d = D'·cosθ2 = D·cosθ1·cosθ2 (4)

[0086] In this way, according to the optical distance measuring device and method of this modification, the distance (absolute value of the distance) from the emission position of the light output unit 11 to the object 4 in the vertical direction of the object 4 can be calculated with even greater accuracy.

[0087] In this modification, an example is shown in which the light emitted from the auxiliary light source (semiconductor laser) in the first optical scanning unit 12_1 is used as the first measurement light, but the present invention is not limited to this. A MEMS mirror may be used as the first optical scanning unit 12_1, and the light emitted from another auxiliary light source (semiconductor laser) provided separately may be reflected by the MEMS mirror and used as the first measurement light. Also, the light emitted from the semiconductor laser (first semiconductor laser) 111 may be branched by another optical branching unit provided separately.

[0088] <Second embodiment> An optical distance measuring device according to a second embodiment of the present invention will be described with reference to FIGS.

[0089] <Configuration of optical distance measuring device> 8, the optical distance measuring device 20 according to this embodiment includes a light output unit 21, a light scanning unit 22, a light receiving unit 23, and a control unit 24. Here, the light output unit 21 has a light source (first light source) 211. In addition, in the light scanning unit 22, another light source (second light source) 221 is mounted on a scan driving unit 222.

[0090] The control unit 24 includes a first light source driving power supply 241 that drives the first light source 211, a second light source driving power supply 242 that drives the second light source 221, an optical scanning control unit 243 that controls the optical scanning unit 22, and an analysis unit 244.

[0091] The analysis unit 244 is connected to the light receiving unit 23 and the optical scanning control unit 243, and calculates the distance to the target object (described later).

[0092] 9 shows the optical system of the optical distance measuring device 20. The optical distance measuring device 20 uses a semiconductor laser 211 as a first light source, a MEMS 222 as a scan driver of the optical scanning unit, a semiconductor laser 221 as a second light source mounted on the MEMS 222, and a CMOS image sensor 23 as a light receiving unit.

[0093] The light emitted from the semiconductor laser 211 is irradiated onto the object 4 as the reference light 1. Here, the position where the reference light 1 is emitted from the semiconductor laser 211 is the emission position of the reference light 1.

[0094] Light emitted from a semiconductor laser 221 mounted on the MEMS 222 is irradiated onto the object 4 as the measurement light 2. Here, the position where the measurement light 2 is emitted from the semiconductor laser 221 is the emission position of the measurement light 2.

[0095] In this way, the optical axis direction of the reference light 1 is fixed, and the optical axis direction of the emitted light of the semiconductor laser 221 mounted on the MEMS 222 is changed over time by driving the MEMS 222. Here, the measurement light 2 is not in a twisted relationship with the reference light 1, and always intersects with it unless it is parallel. In other words, the optical path of the measurement light 2 irradiated to the object 4 and the optical path of the reference light 1 are on the same plane.

[0096] Each light is diffusely reflected by the surface of the object 4, and some of the light is received by the CMOS imaging element 23. Therefore, the CMOS imaging element 23 observes the points where the measurement light 2 and the reference light 1 respectively irradiate the object 4 as bright points.

[0097] The MEMS 222 is a one-axis drive type MEMS similar to that in the first embodiment, and a semiconductor laser 221 mounted on a movable part rotates, so that light emitted from the semiconductor laser scans the target object 4.

[0098] In the optical distance measuring method of this embodiment, as in the first embodiment, the scanning angle θ of the measuring light 2 when the reference light 1 and the measuring light 2 are in focus on the surface of the object 4 is detected, and the distance D from the emission position of the semiconductor laser 211 to the object 4 is calculated using equation (2).

[0099] According to the optical distance measuring method of this embodiment, like the first embodiment, the distance to the object 4 can be accurately measured.

[0100] In particular, even if the direction of light irradiation from the light output section 21 (semiconductor laser 211) to the object 4 has an arbitrary angle with respect to the perpendicular direction to the surface of the object 4, the distance to the object 4 can be measured accurately.

[0101] Furthermore, even if the irradiation direction from light output unit 21 and the direction in which object 4 moves form an arbitrary angle, it is possible to accurately measure the distance from light output unit 21 to object 4 in a direction parallel to reference light 1. In this way, the change in the relative distance from light output unit 21 to object 4 can be accurately measured.

[0102] <Modification> An optical distance measuring device according to a modified example of this embodiment will be described with reference to FIGS.

[0103] The optical distance measuring device 20_2 according to this modification includes, similarly to the second embodiment, a light output unit 21, a light scanning unit 22, a light receiving unit 23, and a control unit 24. Here, the light output unit 21 has a light source (first light source) 211. In addition, in the light scanning unit 22, another light source (second light source) 221 is mounted on the scan driving unit.

[0104] 10(a) and (b) show the optical system of the optical distance measuring device 20_2. The optical distance measuring device 20_2 uses a semiconductor laser 211 as a first light source, a MEMS 222 as a scan driving unit of the optical scanning unit 22, a semiconductor laser 221 as a second light source mounted on the MEMS 222, and a CMOS image sensor 23 as a light receiving unit. Furthermore, the light receiving unit 23 has an angle measurement sensor (angle measurement sensor).

[0105] The light emitted from the first semiconductor laser 211 is irradiated onto the object 4 as the reference light 1. The light emitted from the second semiconductor laser 221 mounted on the MEMS 222 is irradiated onto the object 4 as the measurement light 2. The light from the second semiconductor laser 221 is scanned by driving the MEMS 222.

[0106] 10(a), when the reference light 1 is perpendicularly incident on the object 4 and in focus at a scanning angle (scanning angle of the measurement light 2) α of the optical scanning unit 22, the incident angle of the measurement light 2 on the object 4 is π / 2-α, and the light 3 reflected at a reflection angle π / 2-α out of the measurement light diffusely reflected by the object 4 is received with maximum intensity by the light receiving unit 23. At this time, the light receiving angle β at the light receiving unit 23 is α.

[0107] 10(b), when the reference light 1 is incident at an arbitrary angle θ in the vertical direction of the object 4 and is in focus at a scanning angle α of the optical scanning unit 22, the incident angle of the measurement light 2 to the object 4 becomes π / 2-α+θ, and of the measurement light diffusely reflected by the object 4, light 3 reflected at a reflection angle π / 2-α+θ is received with maximum intensity by the light receiving unit 23. In this case, the incident angle β of the reflected light 3 of the measurement light 2 (and reference light 1) to the light receiving unit 23 is α-2θ.

[0108] In this way, when the reference light 1 is incident at an arbitrary angle θ in the vertical direction of the object 4, the incident angle β of the reflected light 3 of the measurement light 2 (and reference light 1) to the light receiving unit 23 in the focused state is α-2θ, and the change |α-β| is 2θ. Therefore, the angle θ between the incident direction of the reference light 1 and the vertical direction of the object 4 is calculated from θ=|α-β| / 2.

[0109] Therefore, the distance d from the emission position of the light output unit 21 to the object 4 in the vertical direction of the object 4 is calculated by equation (3) using the distance D calculated by equation (2) (the distance from the emission position of the light output unit 21 to the object 4 in the direction parallel to the reference light 1).

[0110] In this way, according to the optical distance measuring device and method of this modified example, the distance D to the object 4 in the direction parallel to the reference light 1 can be corrected, and the distance d (absolute value of the distance) from the emission position of the light output unit 21 to the object 4 in the vertical direction of the object 4 can be calculated.

[0111] Furthermore, similarly to the second modification of the first embodiment, by using another measurement light (second measurement light), the distance (absolute value of the distance) from the emission position of the light output unit 21 in the vertical direction of the object 4 to the object 4 can be calculated more accurately from equation (4).

[0112] In the present embodiment and the modified example, an example has been shown in which the emitted light of a second light source mounted on a MEMS is used as the measurement light, but this is not limited thereto, and the emitted light of the second light source may be reflected by a MEMS mirror and used as the measurement light.

[0113] In an embodiment of the present invention, for example, the light receiving sensitivity can be improved and the measurement accuracy can be improved by setting the light receiving intensity in an unfocused state (such as when the measurement light and reference light are parallel) as an initial value and observing the difference between the light receiving intensity in a focused state and the initial value (the light receiving intensity in the unfocused state).

[0114] Furthermore, when the distance between the distance measuring device and the object is short enough to ensure sufficient light receiving sensitivity in the light receiving section, the amount of light (intensity) of the light source can be reduced, resulting in power saving.

[0115] Furthermore, by converging the measurement light and the reference light using a lens or a mirror, measurement at a longer distance becomes possible.

[0116] Furthermore, if the distance between the distance measuring device and the target object is relatively short, an LED may be used as the light source instead of a semiconductor laser.

[0117] Furthermore, when the distance between the distance measuring device and the object is long, the bright spots of the measurement light and reference light on the object become small, but the focus state can be easily detected by expanding the light diameter according to the distance.

[0118] Furthermore, by mounting the light receiving unit on a telescope, the focusing state at long distances can be measured with high accuracy.

[0119] In addition, the light receiving unit does not have to be disposed on a plane formed by the optical path of the measurement light and the optical path of the reference light from the light source to the object. In addition, the light receiving unit is not limited to a CMOS image sensor, and may be an image sensor such as a CCD image sensor, an optical position detection sensor, or the like.

[0120] Furthermore, the optical branching section is not limited to a half mirror, but a prism, a beam splitter, or the like may also be used.

[0121] Furthermore, the scanning driver of the optical scanning unit is not limited to MEMS, and an actuator or the like may be used.

[0122] In addition, the optical distance measuring device according to the embodiment of the present invention can be used even in the absence of disturbance light. When disturbance light is present, the optical distance measuring device can improve its resistance to disturbance light by using pulse-modulated light as the reference light and the measurement light, and using a narrow-band bandpass filter in the receiver that has a passband that is the same frequency as the high-frequency modulation.

[0123] In the embodiment of the present invention, an example of the structure, dimensions, materials, etc. of each component in the configuration and manufacturing method of the optical distance measuring device is shown, but the present invention is not limited to this. Anything that can exert the function and effect of the optical distance measuring device can be used. [Industrial Applicability]

[0124] INDUSTRIAL APPLICABILITY The present invention can be applied to level gauges that measure the height of a liquid surface in a liquid tank, as well as to safe operation (driving) in the mechanical field including automobiles, and to measuring instruments in the industrial field. [Explanation of symbols]

[0125] 1 Reference light 2. Measurement light 3 Reflected light 4 Surface of the object to be measured (object) 10 Optical ranging device 11 Optical output section 111 Light source 112 Optical branching section 12 Optical scanning unit 121 Light reflecting part 122 Scanning driver 13 Light receiving part 14 Control section 141 Light source drive power supply 142 Optical scanning control unit 143 Analysis Department

Claims

1. An optical distance measuring device for measuring a distance to an object, a light output unit that emits a reference light; a light scanning unit that emits measurement light; a light receiving unit that receives the measurement light and the reference light reflected from the object; Equipped with The focus of the measurement light is scanned on the surface of the object without scanning the focus of the reference light on the surface of the object, and the distance is calculated from the scanning angle of the optical scanning unit when the focus of the measurement light coincides with the focus of the reference light.

1. An optical distance measuring device comprising:

2. An optical distance measuring device for measuring a distance to an object, a light output unit that emits a reference light; a light scanning unit that emits measurement light; a light receiving unit that receives the measurement light and the reference light reflected from the object; Equipped with The focal point of the measurement light is scanned on the surface of the object, and the distance is calculated from the scanning angle of the optical scanning unit when the focal point of the measurement light coincides with the focal point of the reference light according to formula (A).

1. An optical distance measuring device comprising: D = L・tanθ (A) Here, D is the distance, L is the distance between the emission position of the measurement light and the emission position of the reference light, and θ is the scanning angle.

3. An optical distance measuring device as described in Claim 2, characterized in that the distance to be corrected is calculated from equation (B). d= D・cos(|α−β| / 2) (B) Here, d is the distance to be corrected, α is the scanning angle of the measurement light, and β is the light receiving angle at which the light receiving intensity of the reflected light is maximized.

4. The optical paths along which the measurement light and the reference light irradiate the object are on the same plane.

4. The optical distance measuring device according to claim 1, wherein the optical distance measuring device is a distance measuring device having a distance measuring function.

5. the optical output unit has a light source and an optical branching unit, the optical branching unit branches the light from the light source into a first light and a second light, The optical scanning unit reflects the second light at a light reflecting unit and irradiates the object with the second light as the measurement light, The first light is irradiated onto the object as the reference light.

5. The optical distance measuring device according to claim 1,

6. The optical scanning unit has another light source.

5. The optical distance measuring device according to claim 1,

7. The light receiving unit has an angle measuring sensor.

7. The optical distance measuring device according to claim 1,

8. The scanning drive unit of the optical scanning unit is a one-axis drive type MEMS.

8. The optical distance measuring device according to claim 1,

9. An optical distance measuring method for measuring a distance to an object, comprising: irradiating the object with measurement light; irradiating the object with a reference beam; receiving reflected light of the measurement light and the reference light from the object; scanning the measurement light on the surface of the object without scanning the reference light, and detecting a scan angle of the measurement light when a focus of the measurement light coincides with a focus of the reference light; calculating the distance from a scanning angle of the measurement light; An optical distance measuring method comprising:

10. An optical distance measuring method for measuring a distance to an object, comprising: irradiating the object with measurement light; irradiating the object with a reference beam; receiving reflected light of the measurement light and the reference light from the object; scanning the measurement light on a surface of the object and detecting a scan angle of the measurement light when a focus of the measurement light coincides with a focus of the reference light; calculating the distance from a scanning angle of the measurement light; Equipped with An optical distance measuring method, comprising: calculating the distance from equation (A). D = L・tanθ (A) Here, D is the distance, L is the distance between the emission position of the measurement light and the emission position of the reference light, and θ is the scanning angle.

11. 11. The optical distance measuring method according to claim 10, wherein the distance to be corrected is calculated from equation (B). d= D・cos(|α−β| / 2) (B) Here, d is the distance to be corrected, α is the scanning angle of the measurement light, and β is the light receiving angle at which the light receiving intensity of the reflected light is maximized.

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