Object capture device

Abstract

Provided is an object capturing device capable of accurately capturing even an object present in the vicinity. The object capturing device captures an object present in a measurement target space, the object capturing device including: a light emitting section; a light receiving section; and a light scanning section that scans measurement light of a predetermined wavelength emitted from the light emitting section toward the measurement target space and guides reflected light of the measurement light from the object present in the measurement target space toward the light receiving section, the light scanning section including a light guide section that divides a light path that guides the measurement light deflected by a deflection mirror toward the measurement target space and a light path that guides the reflected light toward the light receiving section, and a half mirror that guides the reflected light toward the light receiving section is disposed on the measurement light light path side of the light guide section.

Description

[0001] This application is a divisional application of the patent application filed on February 8, 2018, with application number 201880012165.7 and entitled "Object Capturing Device". Technical Field

[0002] This invention relates to an object capturing device for capturing a specific object existing in a space of objects to be measured. Background Technology

[0003] In semiconductor device manufacturing equipment, a transport trolley is used to move a wafer carrier device containing multiple semiconductor wafers from the loading port of one manufacturing unit to the loading port of another. Such a transport trolley is called an Overhead Hoist Transfer (OHT).

[0004] To avoid contact between the transport trolley and obstacles such as people and machinery, the transport trolley is configured to have a travel section that automatically travels along a travel guide rail provided in the upper space of each manufacturing device, and an item receiving section supported on the travel section. A lifting mechanism is assembled in the item receiving section, which causes the lifting body to move up and down along a predetermined lifting path. The lifting body has a clamping mechanism for grasping the transport object, i.e., the wafer carrier device.

[0005] In order to transport the wafer carrier device according to the layout of each manufacturing unit, the track has a complex shape that not only has simple straight sections but also curved sections, branch sections, and confluence sections. The manufacturing equipment is configured to allow multiple transport trolleys to travel on the same track at intervals.

[0006] In this manufacturing equipment, in order to improve the conveying efficiency of the wafer carrier device, multiple conveyor trolleys are required to travel at high speed on the track. Since the distance between conveyor trolleys tends to shorten, a mechanism is needed to prevent rear-end collisions in case of an accident.

[0007] Patent document 1 discloses a technology as follows: In order to avoid rear-end collisions of the conveyor trolley, a laser rangefinder or other inter-vehicle distance sensor is installed on the conveyor trolley. The relative speed between the trolley and the conveyor trolley in front is calculated based on the inter-vehicle distance measured by the inter-vehicle distance sensor. The travel speed of the trolley is controlled based on the relative speed, thereby avoiding rear-end collisions.

[0008] However, when the leading transport trolley travels on a curved section of the track, it is not only impossible to detect the leading transport trolley because it is out of the scanning range of the measuring light output from the laser rangefinder, but it is also possible to misdetect reflected light from the outer panels of various manufacturing devices, or reflected light from other traveling trolleys, as reflected light from the leading transport trolley.

[0009] Therefore, Patent Document 2 proposes a distance measuring device as follows: a distance measuring device consisting of a scanning unit and a distance calculation unit is arranged at the front of a conveyor trolley traveling along a track. The scanning unit scans the modulated measuring light in a planar manner, and the distance calculation unit calculates the distance to the object based on the time delay between the measuring light scanned by the scanning unit and the reflected light from the object being detected. The distance measuring device detects the workshop distance of the conveyor trolley based on the reflected light from the retroreflective member arranged at the rear of the conveyor trolley traveling in front.

[0010] The distance measuring device includes an identification unit that identifies whether the light is reflected from a retroreflective component based on the correlation between at least two of the following: multiple scanning angles of the measuring light scanned by the scanning unit, the distances corresponding to each scanning angle calculated by the distance calculation unit, and the intensity of the reflected light corresponding to each scanning angle.

[0011] Prior art literature

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2007-25745

[0014] Patent Document 2: Japanese Patent Application Publication No. 2011-69671 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] However, even the distance measuring device described in Patent Document 2 cannot completely eliminate the possibility that the identification unit may misjudge reflected light from the wall of the manufacturing device or the like as reflected light from the retroreflective member of the transport trolley.

[0017] The reason is that, depending on the distance between the distance measuring device and the wall surface illuminated by the measuring light, there are cases where the reflection characteristics of the wall surface illuminated by the measuring light are similar to the reflection characteristics of the retroreflective component arranged at the rear of the conveyor trolley. For example, the wall surface is made of a metal plate such as aluminum and the measuring light is incident on the wall surface from a roughly vertical direction, or the wall surface is made of a white coated surface after wrinkling.

[0018] In such a situation, to avoid misjudgment, the correlation between each manufacturing device and the judgment criterion must be adjusted separately, which requires a very complicated operation.

[0019] The same problem is not limited to the aforementioned aerial unmanned transport vehicles (OHTs); it can also occur in transport trolleys that are guided by multiple landmarks along their travel path and travel to their destination unmanned without deviating from the path. Such transport trolleys are abbreviated as AGVs (Automated Guided Vehicles).

[0020] The AGV is equipped with a distance measuring device that scans and outputs measuring light toward landmarks arranged along the path. The distance measuring device detects the reflected light from the regressive reflective components that constitute each landmark to confirm the position, or it can be configured to detect obstacles such as people or objects existing in the driving path.

[0021] However, when reflected light from the walls of manufacturing equipment or other sources is misjudged as reflected light from landmarks, it may cause a deviation from the driving path.

[0022] The object of the present invention is to provide an object capturing device capable of determining whether an object is a target object, in view of the above-mentioned problems.

[0023] Solution for solving the problem

[0024] The first characteristic structure of the object capturing device of the present invention, as described in technical solution 1 of the present invention, is as follows: an object capturing device for capturing an object existing in a measurement object space, wherein the object capturing device comprises: a light emitting unit; a light receiving unit; a light scanning unit that scans a measurement light of a predetermined wavelength emitted from the light emitting unit toward the measurement object space and guides reflected light from the object in the measurement object space toward the light receiving unit; and a polarization filter comprising a polarizer disposed in the light scanning unit that allows only light vibrating along a first direction in the measurement light to pass through, and a polarizer that allows only light vibrating along a second direction orthogonal to the first direction in the reflected light to pass through.

[0025] Linearly polarized light vibrating along a first direction from the measurement light emitted from the light-emitting unit passes through a polarizer and scans into the measurement object space. Linearly polarized light vibrating along a second direction orthogonal to the first direction from the reflected light from the object passes through a polarizer and is guided towards the light-receiving unit. Since the light scanning unit is equipped with a polarizer and a polarizer, the polarization direction of the measurement light does not change with scanning, and the polarization direction of the reflected light also does not change. If the reflective properties of the reflective surface of the object being captured have reflective properties that rotate the polarization direction of the measurement light by 90 degrees, the object being captured can be reliably identified.

[0026] The second feature of the present invention, as described in technical solution 2 of the present invention, is that, based on the first feature described above, a circular polarizing plate is disposed between the light-emitting part and the polarizing plate.

[0027] The measurement light, after being circularly polarized by the circular polarizer, is incident on the polarizer, thereby easily obtaining linearly polarized light vibrating in the first direction. As a result, it is not necessary to adjust the relative position of the light-emitting part and the polarizer to make the polarization direction of the linearly polarized light emitted from the light-emitting part consistent with the polarization direction based on the polarizer.

[0028] The third feature of the present invention, as described in technical solution 3 of the present invention, is that, based on the second feature described above, a second polarizer is disposed between the light-emitting part and the circular polarizer.

[0029] By adjusting the second polarizer so that the polarization surface of the incident light is incident at an azimuth angle of 45 degrees relative to the high-speed axis or low-speed axis of the circular polarizer, linearly polarized light can be changed into circularly polarized light that is close to a perfect circle. As a result, the measurement light after obtaining appropriately linearly polarized light using the polarizer provided in the optical scanning unit can be obtained.

[0030] The fourth feature structure of the present invention, as described in technical solution 4 of the present invention, is that, based on any of the first to third feature structures described above, the optical scanning unit includes: a deflecting mirror; and a light guiding unit that divides the optical path that guides the measurement light deflected by the deflecting mirror toward the measurement object space and the optical path that guides the reflected light toward the light receiving unit, wherein the polarizer is disposed on the measurement light optical path side of the light guiding unit and the polarizer is disposed on the reflected light optical path side of the light guiding unit.

[0031] The optical path is divided into a measurement optical path and a reflected optical path by the light guiding section. When the measurement light emitted from the light-emitting section travels in the measurement optical path, linearly polarized light that vibrates only along the first direction passes through the polarizer and scans into the space of the measurement object. When the reflected light from the object travels in the reflected optical path, linearly polarized light that vibrates only along the second direction orthogonal to the first direction passes through the polarizer and is received by the light receiving section.

[0032] The fifth feature of the present invention, as described in technical solution 5 of the present invention, is as follows: an object capturing device for capturing an object existing in a measurement object space, wherein the object capturing device comprises: a light-emitting unit; a light-receiving unit; and a light scanning unit that scans a measurement light of a predetermined wavelength emitted from the light-emitting unit toward the measurement object space and guides reflected light from an object in the measurement object space toward the light-receiving unit. The light scanning unit comprises a light guiding unit that divides the light path for guiding the measurement light, which has been deflected by the deflecting mirror, toward the measurement object space and the light path for guiding the reflected light toward the light-receiving unit. A semi-transparent lens for guiding the reflected light toward the light-receiving unit is disposed on the measurement light path side of the light guiding unit.

[0033] Without a semi-transparent mirror and when the object illuminated by the measuring light is near the object capturing device, the diameter of the measuring light beam emitted from the light guide is small, and the spread of the beam of reflected light from the object is also small. The diameter of the reflected light traveling in the reflected light path is close to the diameter of the measuring light traveling in the measuring light path. As a result, the amount of light guided to the receiving part is reduced, potentially leading to inaccurate distance detection. In such cases, if a semi-transparent mirror is provided, the reflected light from the object is reflected by the semi-transparent mirror and guided to the receiving part, enabling accurate detection even of nearby objects.

[0034] The sixth feature of the present invention, as described in technical solution 6 of the present invention, is that, based on any of the first to fifth feature structures described above, the object capturing device includes a housing, the portion of the housing that forms the path of the measuring light and the reflected light being made of a material that allows the measuring light to pass through and has low polarization characteristics relative to the measuring light.

[0035] The material used for the optical window, which forms the path for the measurement light and the reflected light within the housing, has low polarization characteristics. This suppresses changes in the polarization characteristics of the measurement light and the reflected light passing through the optical window, thus preventing a decrease in detection accuracy.

[0036] The seventh feature structure of the present invention, as described in technical solution 7 of the present invention, is that, based on any of the first to sixth feature structures described above, the light-emitting part has multiple light sources with different wavelengths, and the multiple light sources with different wavelengths are switched and driven synchronously with the scanning cycle of the light scanning part.

[0037] The light source with different wavelengths is switched and driven synchronously with the scanning cycle of the light scanning unit. At least one scanning cycle is performed with a constant wavelength measurement light, and the wavelength of the measurement light is not switched in the middle of one scanning cycle.

[0038] Invention Effects

[0039] As described above, the present invention provides an object capture device capable of determining whether an object is a target for capture. Attached Figure Description

[0040] Figure 1 This is an explanatory diagram of semiconductor device manufacturing equipment and a transport trolley that moves along a guide rail.

[0041] Figure 2 This is an illustration of the wafer carrier handover process between the transport trolley and the manufacturing equipment.

[0042] Figure 3 This is a 3D view of the conveyor trolley.

[0043] Figure 4 This is a functional block diagram illustrating the conveying control unit mounted on the conveying trolley.

[0044] Figure 5 (a), (b), and (c) are diagrams illustrating the positional relationship of two conveyor trolleys moving along the guide rail.

[0045] Figure 6 This is an illustration of the appearance of the object capture device.

[0046] Figure 7 This is a diagram illustrating the internal structure of an object capture device.

[0047] Figure 8 This is a functional block diagram illustrating the control unit assembled in the object capture device.

[0048] Figure 9 (a), (b), and (c) are illustrations of the relationship between distance and scanning angle range.

[0049] Figure 10 (a), (b), and (c) are illustrations of the correlation between distance and the distribution of reflected light intensity.

[0050] Figure 11 Figures (a), (b), and (c) illustrate the relationship between the reflective properties of the reflector and the intensity distribution of reflected light.

[0051] Figure 12 This is a flowchart illustrating the operation of the object discrimination unit.

[0052] Figure 13 (a) and (b) are explanatory diagrams of a regressive reflective element used as a reflector.

[0053] Figure 14This is an explanatory diagram showing the internal structure of an object capturing device according to another embodiment.

[0054] Figure 15 This is an explanatory diagram showing the internal structure of an object capturing device according to another embodiment.

[0055] Figure 16 This is an explanatory diagram showing the internal structure of an object capturing device according to another embodiment.

[0056] Figure 17 (a) is a detection characteristic diagram of reflected light relative to multiple reflective components. Figure 17 (b) is a graph showing the detection characteristics of reflected light as the angle changes relative to the reflector. Figure 17 (c) is a detection characteristic diagram of reflected light relative to the scanning direction. Figure 17 (d) is a detection characteristic diagram of reflected light relative to the scanning direction when the angle of the reflector is changed.

[0057] Figure 18 This is an explanatory diagram of the raw materials for the reflector (reflective component).

[0058] Figure 19 (a) and (b) are illustrations of the reflective properties of the reflective sheet.

[0059] Explanation of reference numerals in the attached figures

[0060] 1: Manufacturing equipment

[0061] 5: Traveling guide rail

[0062] 10: Conveyor trolley

[0063] 20: Object capture device

[0064] 21: Light-emitting part

[0065] 22: Light-receiving part

[0066] 23: Optical Scanning Unit

[0067] 24: Projection Lens

[0068] 25: Light-receiving lens

[0069] 40: Reflective sheet

[0070] 54: Light guiding section

[0071] 70: Driving Control Unit

[0072] 80: Control Department

[0073] 81: Distance Calculation Unit

[0074] 82: Object discrimination unit

[0075] 100: Manufacturing equipment

[0076] AN: Polarizer

[0077] PL, PL´, PL´´: polarizer. Detailed Implementation

[0078] The following describes an embodiment of an unmanned transport trolley that incorporates the object capture device of the present invention into a semiconductor device manufacturing equipment.

[0079] like Figure 1 As shown, the semiconductor device manufacturing equipment 100 includes: various manufacturing apparatuses 1 (1a-1l) arranged along a predetermined path for sequentially performing predetermined processes on semiconductor wafers; travel rails 5 suspended from a ceiling along each manufacturing apparatus 1; and multiple transport trolleys (OHTs) 10 that travel along the travel rails 5 to automatically transport semiconductor wafers W between the manufacturing apparatuses 1 (1a-1l). Each manufacturing apparatus 1 (1a-1l) is divided into partitions 6 and 7 for each integral manufacturing process. Multiple semiconductor wafers W are housed in a wafer carrier 3.

[0080] The travel guide rail 5 is configured to have not only a simple straight section, but also curved sections, branch sections, and converging sections. For example, it is composed of an inter-process guide rail 5a that connects the various partitions 6 and 7, an intra-process guide rail 5b that connects the manufacturing devices 1 installed in the various partitions 6 and 7, a branch guide rail 5c that connects the inter-process guide rail 5a and the intra-process guide rail 5b, a retraction guide rail 5d that allows the transport trolley 10 traveling in the intra-process guide rail 5b to temporarily retract, and a bypass guide rail 5e for the transport trolley 10 to the storage machine ST wafer carrier 3.

[0081] Branch guide rail 5c is a guide rail that connects inter-process guide rail 5a and intra-process guide rail 5b. The moving conveyor trolley 10 travels along branch guide rail 5c, thereby moving back and forth between inter-process guide rail 5a and intra-process guide rail 5b.

[0082] The retraction guide rail 5d is branched from the process guide rail 5b, for example, when the conveyor trolley 10 is temporarily retracted from the process guide rail 5b for maintenance or other purposes.

[0083] The bypass guide rail 5e branches off from the inter-process guide rail 5a and is used in situations where the wafer carrier 3 held by the transport trolley 10 traveling on the inter-process guide rail 5a is temporarily stored in the storage machine ST.

[0084] like Figure 2 and Figure 3As shown, the travel guide rail 5 is suspended from the ceiling at appropriate intervals by the support member 11, and is composed of a tubular body with a rectangular cross-section having a slit-like opening 5A formed in the lower wall along the long side direction. The transport trolley 10 consists of a travel part 10A that travels along the inner upper surface 5B of the lower wall of the tubular body, sandwiching the opening 5A, and a holding part 10B that is connected to the travel part 10A by means of a connecting member 10G and is located below the lower wall of the tubular body.

[0085] The driving unit 10A is configured to have a driving base and a pair of front and rear wheels mounted on the driving base, and is equipped with a transport control unit, etc. The transport control unit controls the driving motor that drives the wheels and the lifting mechanism 10E described later, thereby transporting the wafer carrier 3 to the manufacturing apparatus 1, which is the destination.

[0086] Figure 4 The functional block structure of the transport control unit 70 mounted on each transport trolley 10 is shown. The transport control unit 70 includes a travel control unit 71 composed of a microcomputer and its peripheral circuits, a clamping mechanism control unit 72 connected to the travel control unit 71, a main communication unit 73, and an optical communication unit 10F.

[0087] The conveying control unit 70 is based on the system controller H (reference) Figure 1 The instructions are given to perform the following control: grab the wafer carrier 3 placed on the loading port 2 of each manufacturing device 1 (1a~1l), travel between each manufacturing device 1 or between storage machines ST where the wafer carrier 3 is temporarily stored in advance, and place the wafer carrier 3 on the loading port 2 which is the destination for transport.

[0088] The holding part 10B is equipped with a lifting body 10D, which has a clamping mechanism 10C for gripping the wafer carrier 3; and a lifting mechanism 10E, which has a belt and a winding motor for lifting the lifting body 10D along a predetermined lifting path.

[0089] Furthermore, an optical communication unit 10F is assembled on the bottom side of the gripping part 10B to communicate locally with the optical communication unit 2C provided in each manufacturing device 1. When the driving control unit 71 recognizes, based on instructions from the system controller H, that it has arrived near the destination manufacturing device 1 and that optical communication has been established between the optical communication units 2C and 10F, it stops controlling the driving motor. It should be noted that the signal transmission medium used for local communication can be a wireless communication medium, and is not limited to light; radio waves or the like can also be used. That is, a wireless communication unit can be used instead of an optical communication unit.

[0090] Furthermore, when the lifting mechanism 10E is lowered by controlling the roll-up motor and the wafer carrier 3 is held by the gripping motor driven by the clamping mechanism control unit 72, the lifting mechanism 10E is raised by controlling the roll-up motor and the wafer carrier 3 is transported toward the manufacturing apparatus 1 or the conveying destination.

[0091] like Figure 3 As shown, an object capturing device 20 is assembled on the front surface side of each conveyor trolley 10 in the gripping part 10B in the direction of travel, and a reflective sheet 40 of a specified size is attached on the rear surface side in the direction of travel.

[0092] like Figure 5 As shown in (a) to (c), the object capturing device 20 is configured to scan the measuring light forward in the direction of travel and detect the reflected light from the reflector 40f attached to other conveyor carriages 10f traveling ahead. It then calculates the inter-carriage distance between itself and the other conveyor carriages 10f and outputs it to the conveying control unit 70 (travel control unit 71). When the conveying control unit 70 determines that the inter-carriage distance input from the object capturing device 20 is shorter than the allowable value, it controls the conveyor carriage 10 to slow down or stop to avoid collision. It should be noted that it can also be configured such that a collision avoidance control unit is provided in the object capturing device 20, and a control signal for slowing down or stopping the conveyor carriage 10 is output from the object capturing device.

[0093] The other conveyor trolleys traveling ahead are from... Figure 5 The straight travel guide rail shown in (a) enters Figure 5 When traveling on a curved travel rail as described in (b), when the rail comes from... Figure 5 The reflected light from the plate of the manufacturing device 1, etc., which is located on the extension line of the travel guide 5 that is about to reach the bend, is mistakenly detected as reflected light from the reflective sheet 40f attached to the conveyor trolley 10f traveling ahead. When the conveyor trolley 10 slows down or stops, it is difficult for the conveyor trolley 10 to start moving again from the stopped state. Therefore, the object capturing device 20 is provided with an object discrimination unit, which determines whether the detected reflected light is reflected light from the reflective sheet 40f attached to another conveyor trolley traveling ahead.

[0094] The object capturing device 20 will now be described in detail.

[0095] (First embodiment of the object capturing device)

[0096] Figure 6 The appearance of the object capturing device 20 is shown. Figure 7 The internal structure of the object capturing device 20 is shown. (Example) Figure 6 As shown, the object capturing device 20 includes a lower housing 20A with a generally rectangular parallelepiped shape, and an upper housing 20B with an optical window 20C that is generally cylindrical in shape. A signal connection section CN and a display section 20D are provided in the lower housing 20A.

[0097] like Figure 7 As shown, the housings 20A and 20B of the object capturing device 20 house a light-emitting part 21, a light-receiving part 22, a light-scanning part 23, a light-projecting lens 24, a light-receiving lens 25, and a signal processing substrate 30 and 31.

[0098] A light scanning unit 23 is constructed using a motor 50 mounted on the inner wall of the upper surface of the upper housing 20B and a deflector 52 rotatably fixed to the rotation shaft 51 of the motor 50. The deflector 52 is tilted at a 45-degree angle relative to the rotation shaft 51, and an encoder 53 is mounted on the rotation shaft 51 to measure the rotation speed of the motor 50. This encoder 53 functions as a light scanning angle detection unit.

[0099] On the optical axis P, which is coaxial with the vertically positioned rotation axis 51, a light-receiving lens 25 and a light-receiving part 22 are arranged on the opposite side of the motor 50, separated by a deflection mirror 52. The light-receiving lens 25 and the light-receiving part 22 are positioned differently in the vertical direction. An opening, formed by cutting a tube in the center of the light-receiving lens 25, is formed. A light-emitting part 21 is arranged at the lower end of the opening, and a light-projecting lens 24 is arranged above the light-emitting part 21.

[0100] The light guide 54 is fixed to the deflector 52 in a manner that rotates integrally with the deflector 52. The light guide 54 rotates integrally with the deflector 52 and divides the measurement light path L1, which guides the measurement light deflected by the deflector 52 to the measurement object space, and the reflected light path L2, which uses the deflector 52 to deflect the reflected light and guide it to the light receiving part 22.

[0101] The light-emitting unit 21 is composed of a laser diode with an infrared wavelength mounted on a substrate supported in a cantilever shape. The coherent measurement light emitted from the laser diode is shaped into parallel light by the projection lens 24 and incident along the optical axis P towards the deflection mirror 52. After being deflected by 90 degrees, it is irradiated from the optical window 20C into the measurement object space through the measurement light path L1 of the inner region divided by the light guide unit 54 along the optical axis P1.

[0102] The measuring light is directed onto the surface of an object existing in the measuring object space. A portion of the reflected light travels along the optical axis P1 from the optical window 20C through the reflected light path L2 of the outer region divided by the light guide 54 and enters the deflecting mirror 52. After being deflected by 90 degrees by the deflecting mirror 52, it is focused by the light receiving lens 25 and enters the light receiving part 22.

[0103] The flange formed around the light-receiving lens 25 is supported by the lens holder 26, and the substrate constituting the light-emitting part 21 is supported by the lens holder 26. Furthermore, the substrate to which the light-receiving part 22 is fixed, and the signal processing substrates 30 and 31 are supported by a plurality of legs 27 that support the lens holder 26.

[0104] Furthermore, in the light guide section 54 assembled in the light scanning section 23, opposite the optical window 20C, a polarizer PL is disposed at the exit end of the measuring light path L1, and a polarizer AN is disposed at the entrance end of the reflected light path L2. That is, the polarizer PL is disposed inside the light guide section 54, and the polarizer AN is disposed outside the light guide section 54.

[0105] Using a polarizer PL, only light vibrating along a first direction is allowed to pass through the optical path of the measured light. Using a polarizer AN, only light vibrating along a second direction orthogonal to the first direction is allowed to pass through the optical path of the reflected light. In addition, a quarter-wavelength plate 28, as an example of a circular polarizer, is arranged immediately behind the projection lens 24 along the light emission direction.

[0106] Measurement light emitted from the laser diode of the light-emitting unit 21 and linearly polarized in a predetermined direction is transformed into circularly polarized light by passing through the 1 / 4 wavelength plate 28, and then into linearly polarized light in a direction, for example, orthogonal to the scanning direction, by passing through the polarizer PL.

[0107] As polarizers (PL) and detectors (AN), they can be made of wire grids with fine metal grids formed on the surface of glass, crystalline materials that utilize the birefringence of the material itself to adjust the polarization composition of light, etc.

[0108] By arranging an optical component on the reflective surface of the object being captured, such that the polarization direction is rotated by 90 degrees, the polarization direction of the reflected light is rotated by 90 degrees relative to the polarization direction of the measured light. As such an optical component, a retroreflective sheet composed of trihedral corner reflector elements or a half-wavelength plate is preferred.

[0109] Figure 13 (a) shows a trihedral corner reflector element (also known as a microprism). The unit element is constructed using three mutually orthogonal mirrors 41, 42, and 43. Light incident on such a trihedral corner reflector element is reflected in the direction of incidence.

[0110] like Figure 13 As shown in (b), the linearly polarized light measured by the polarizer PL is reflected by the three surfaces of the trihedral corner reflector element, thus becoming linearly polarized light with a polarization direction changed by 90 degrees, and then passes through the polarizer AN.

[0111] Even if the measurement light after passing through the polarizer PL is reflected towards a metal plate such as aluminum, the polarization direction of the reflected light will not change, so the reflected light will not pass through the polarizer AN. When the measurement light after passing through the polarizer PL is reflected towards a white scattering plate, the polarization direction is disrupted, resulting in a reflection of circularly polarized light and linearly polarized light pointing in various angular directions. Therefore, the amount of reflected light passing through the polarizer AN is approximately halved.

[0112] The optical scanning unit 23 includes a polarizer PL and a polarizer AN, which rotate integrally with the deflection mirror 52. Therefore, the polarization direction of the measurement light emitted during scanning does not change, and the polarization direction of the incident reflected light also does not change. As long as the reflective properties of the reflective surface of the target object have reflective properties that rotate the polarization direction of the measurement light by 90 degrees, the target object can be reliably identified.

[0113] In order to ensure that the polarization characteristics do not change when the light passes through the optical window 20C, the raw materials used for the optical window 20C, which forms the path of the measurement light and the reflected light, are preferably acrylic resins with low birefringence, optical glass, or other materials that allow the measurement light to pass through and have low polarization characteristics relative to the measurement light.

[0114] The signal processing substrate 30 is provided with a control unit 80 for controlling the object capturing device 20, and the signal processing substrate 31 is provided with LED and liquid crystal display elements for displaying various information on the display unit 20D. The signal processing substrate 30, the light-emitting unit 21 and the light-receiving unit 22 are interconnected by signal lines, and a signal cable extends from the signal processing substrate 30. The signal cable exchanges signals with external devices through the signal connection part CN provided in the lower housing 20A.

[0115] Figure 8 The functional block structure of the control unit 80 is shown. The control unit 80 is configured to include a microcomputer, a digital signal processor, etc., and thus includes: a light emission control unit 84, which controls the timing of light emission from the light emission unit 21; a distance calculation unit 81, which calculates the distance to the detected object based on the time difference or phase difference between the measurement light scanned by the light scanning unit 23 and the reflected light from the object; a correction calculation unit 83, which corrects the distance calculated by the distance calculation unit 81; and an object discrimination unit 82.

[0116] The method of calculating distance based on the time difference between the measured light and the reflected light is called the Time-of-Flight (TOF) method. The distance d is calculated using the following mathematical formula 1. Here, C is the speed of light, and ΔT is the time difference.

[0117] (Mathematical Formula 1)

[0118] d = (1 / 2) × C / ΔT

[0119] The method of calculating distance based on the phase difference between the measured light and the reflected light after AM modulation of the light source at a specified modulation frequency is called the AM method. The distance d is calculated using the following mathematical formula 2. Here, φ is the measured phase difference, C is the speed of light, and F is the modulation frequency of the light source.

[0120] (Mathematical Formula 2)

[0121] d=(1 / 2)×(φ / 2π)×C / F

[0122] The correction calculation unit 83 is a block for correcting errors caused by component deviations of the object capturing device 20. It is a function block for calculating correction coefficients in a way that makes the distance calculated based on the reflected light from the reference reflector 55 partially installed on the inner wall of the upper housing 20B a predetermined distance.

[0123] The following explanation will use the Time-of-Flight (TOF) method as an example. It should be noted that the same applies to the AM (Advanced Mode) method.

[0124] The object discrimination unit 82 is configured to identify and measure the light reflection position, i.e., the distance and direction from the object capturing device 20 to the reflection position, based on the scanning angle detected by the scanning angle detection unit 53 and the distance calculated by the distance calculation unit 81 corresponding to the scanning angle using the correction coefficient calculated by the correction calculation unit 83 (hereinafter referred to as "the distance calculated by the distance calculation unit 81"). Based on the multiple reflection positions determined by the identified distance and direction, it determines whether the detected object is a target object for capture, and if it is determined to be a target object for capture, it outputs the distance and / or direction to the travel control unit 71 of the transport trolley 10.

[0125] The object capturing device 20 described in this embodiment has the following specifications: a detection distance of 50mm to 7000mm, a scanning angle range of 270 degrees, a scanning time of 25ms, an angular resolution of 0.25 degrees, and the reflective sheet 40 has dimensions of 300mm in width and 270mm in height. It should be noted that these specifications are merely examples and are not intended to limit the invention to these specifications.

[0126] The object discrimination unit 82 is configured to identify a continuous range of scanning angles where the difference between a certain scanning angle calculated by the distance calculation unit 81 and the distances at adjacent scanning angles is below a predetermined threshold as the size of the object along the scanning direction. The object is determined to be the target object based on whether the scanning angle range corresponds to the reference scanning angle range of the target object and whether the intensity distribution of reflected light within the scanning angle range corresponds to the reference intensity distribution of reflected light from the target object.

[0127] The reference scanning angle range for capturing an object refers to the scanning angle range corresponding to the reference distances calculated within the scanning angle range. As the reference distance, the minimum distance, maximum distance, center value, average value, etc., from the object capturing device 20 to the object can be used; in this embodiment, the average value is used.

[0128] like Figure 9 As shown in (a), if the distance d calculated by the distance calculation unit 81 using a certain scanning angle θ and the distance calculated using the scanning angle θ ± Δθp (Δθp = 0.25 degrees) adjacent to the scanning angle θ are both below a predetermined threshold Δd, it is determined that the object corresponding to the distance d is the same object.

[0129] If the scanning angle range ±Δθ, which is equivalent to the size of the object along the scanning direction, is based on the reference distance d representing each distance d within that scanning angle range ±Δθ, then... ref The set reference scanning angle range θ of the target object ref In this way, it can be determined that the detected object is the target object.

[0130] That is, when the reflector 40 is located at a reference distance d from the object capturing device 20. ref In the case of the position, the scanning angle corresponding to the lateral length of the reflector 40 (300 mm), which is the dimension of the scanning direction, becomes the reference scanning angle range θ. ref .

[0131] Therefore, as Figure 9 As shown in (b), the reference scan angle range θ ref Able to utilize the reference distance d ref The variable is determined by a function like the one described below.

[0132] θ ref =2·tan -1 (W / 2·d) ref )

[0133] Here, W is the lateral width of the reflector 40 along the scanning direction of the measuring light. As described above, in this embodiment, the reference distance d... ref The average distance from the object capture device 20 to the object is used.

[0134] In addition, such as Figure 10 As shown in (a), if the intensity distribution I of the reflected light detected within a scanning angle range ±Δθ, which is equivalent to the size of the object along the scanning direction, is the same as the reference intensity distribution I of the reflected light from the captured object. refCorrespondingly, the detected object can be identified as the target object. That is, if the scanning direction size and reflected light intensity distribution of the target object are set to be different from other objects, it can be reliably identified as the target object.

[0135] like Figure 10 As shown in (b), the baseline intensity distribution I ref The intensity I can be obtained using a function that takes the distance d from the object capturing device 20 to the reflector 40 as a variable. Generally, the intensity I of the reflected light is inversely proportional to the square of the distance d. Therefore, the shorter the distance d from the reflector 40, the greater the intensity I of the reflected light, and the longer the distance d from the reflector 40, the smaller the intensity I of the reflected light. That is, the reference intensity distribution is determined with the distance from the object as the indicator.

[0136] Furthermore, preferably, the aforementioned reference scanning angle range θ ref and reference intensity distribution I ref The degree of deviation of the scanning angle range from the scanning reference position of the measuring light is used as an indicator.

[0137] If the angle at which the target object is located within the scanning range of the measuring light changes, the scanning direction dimensions and reflected light intensity distribution of the target object will change even if the reference distance remains the same. Even in such cases, by determining the reference scanning angle range and reference intensity distribution based on the degree of deviation of the scanning angle range from the scanning reference position of the measuring light, the target object can be identified more reliably.

[0138] As the reference position for measuring light, the scanning starting angle can be arbitrarily selected ( Figure 9 (a) The position where θ = 0 degrees), the scanning endpoint angle ( Figure 9 (a) The position of θ=270 degrees), the scanning angle at the center of the scanning range ( Figure 9 The position of θ=135 degrees in (a) can be used as a measure of the degree of deviation in the scanning angle range, for example, by using the starting angle of the scanning angle range ( Figure 9 (a) The position of θ = 135 degrees - Δθ, and the endpoint angle ( Figure 9 (a) The position of θ = 135 degrees + Δθ or the center angle ( Figure 9 The angle difference between any chosen angle (such as the position of θ=135 degrees in (a)) and the aforementioned scanning reference position is used to represent the reference scanning angle range θ. Based on a function that sets this angle difference as a variable, the reference scanning angle range θ is determined. ref and reference intensity distribution I ref That's all.

[0139] Furthermore, preferably, the reference scanning angle range θ refand reference intensity distribution I ref The tilt angle of the target object (reflector 40) relative to the optical axis of the measurement light, which is determined based on various distances within the scanning angle range, is used as an indicator.

[0140] Based on the tilt angle between the optical axis of the measured light and the target object (reflector 40), even if the reference distance d ref Similarly, the scanning direction dimensions and reflected light intensity distribution of the target object will also change. Even under such circumstances, the slope of the target object (reflector 40) relative to the optical axis of the measurement light is calculated based on each distance within the scanning angle range, and the reference scanning angle range θ is determined using the calculated tilt angle of the target object (reflector 40) as an indicator. ref and reference intensity distribution I ref This allows for more reliable identification of objects as targets.

[0141] Figure 9 (c) shows the distances within the scanning angle range obtained after the reflective surface of the captured object is tilted at an angle φ relative to the optical axis of the measuring light. Based on the distances at both ends of the reflective surface along the scanning direction within the scanning angle range of the captured object, the tilt angle φ can be geometrically determined, and the average value of each distance within the scanning angle range can be calculated as reference distances d1, d2, and d3. For example, as shown in the following mathematical formula, the obtained reference distances d1, d2, and d3 can be used to calculate the average value of each distance within the scanning angle range. ref The scanning angle range θ is obtained by setting the tilt angle φ as a function of variables. ref .

[0142] θ ref =2·tan -1 (W·cosθ / 4·d) ref )

[0143] Figure 10 (c) shows the intensity I of each reflected light within the scanning angle range obtained after the reflective surface of the captured object is tilted at an angle φ relative to the optical axis of the measuring light. Figure 9 Similarly, (c) can utilize the obtained baseline distance d ref The baseline intensity distribution θ is obtained by setting the tilt angle φ as a function of variables. ref .

[0144] The aforementioned reference scanning angle range θ ref and reference intensity distribution I ref It can be configured so that the object discrimination unit 82 calculates the value using the function operation described above, or the reference distance d can be used. ref The tilt angle φ is divided into multiple categories, and the reference scanning angle range θ corresponding to each category is pre-defined. ref and reference intensity distribution Iref The reference data is stored in the memory.

[0145] Figure 11 (a) shows the reference intensity distribution I within a scanning angle range of 0 degrees (vertical incidence) ± 45 degrees. ref Examples vary depending on the reflective characteristics of the reflector 40. If the reflector 40 is a scattering body such as white paper, the intensity distribution of the reflected light detected by the light-receiving part 22 will be approximately flat even when the scanning angle of the measured light changes.

[0146] In contrast, if the reflector 40 is a mirror, such as an aluminum metal plate, the measuring light undergoes specular reflection. Therefore, when the measuring light is incident on the metal plate from a roughly perpendicular direction, the intensity of the reflected light detected by the light-receiving part 22 is relatively high. When the incident angle of the measuring light deviates from the perpendicular direction, the intensity of the reflected light becomes extremely low. Thus, the intensity distribution of the reflected light exhibits a characteristic of peaking at the center of the perpendicularly incident measuring light and gradually decreasing before and after the peak.

[0147] When a retroreflective element is used as the reflector sheet 40, an intensity distribution that is flat and has a very high intensity throughout the entire area, similar to that obtained from a scattering object such as white paper, can be obtained. As the retroreflective element, the reflector sheet arranged with the aforementioned trihedral corner reflector elements is preferred.

[0148] Figure 11 (b) shows the intensity distribution of reflected light from a reflector arranged in an orientation approximately perpendicular to the optical axis of the measurement light at a scanning angle of 135 degrees. Even at a constant distance d, the reflected light intensity Ip is relatively flat when the reflector surface is a scattering surface, the reflected light intensity Im is extremely large at the center of the perpendicularly incident area and small at the edges when the reflector surface is a mirror surface, and the reflected light intensity Is is relatively flat and larger than the former two when the reflector surface is composed of a retroreflective element.

[0149] Figure 11 (c) shows the intensity distribution of reflected light from a reflector slightly tilted from an orientation perpendicular to the optical axis of the measuring light. The intensity distribution is shown when the reflector surface is a scattering surface and when the reflector surface is composed of a retroreflective element. Figure 11 Compared to (b), the change is not significant, but when the reflecting surface is a mirror, the intensity distribution varies considerably depending on the incident angle.

[0150] Therefore, by employing a reflector 40 with reflective characteristics different from those of objects that may be falsely detected, it is possible to appropriately identify and capture the target object, and by using a reference scanning angle range θ that reflects the characteristics of the reflector 40. refand reference intensity distribution I ref It can determine whether it is a target object, and can appropriately capture the target object regardless of its position in the scanning range of the measuring light.

[0151] Figure 12 The flowchart of the object capture steps performed by the object discrimination unit 82 is shown.

[0152] When the object discrimination unit 82 obtains position data (S1) for each scan of the measuring light using the distance calculated by the distance calculation unit 81 and corrected by the correction calculation unit 83, and the corresponding scanning angle, it performs object discrimination processing (S2) based on the multiple position data, where the difference between each distance at a certain scanning angle and the scanning angle adjacent to that scanning angle is determined to be below a predetermined threshold, and the continuous scanning angle range is above the predetermined threshold.

[0153] For each extracted object, a reference distance is calculated (S3), the reference scanning angle range is derived using the function described above (S4), and the reference intensity distribution is derived using the function described above (S5). It should be noted that the reference scanning angle range and reference intensity distribution can also be configured such that the data is pre-set and stored in the memory based on the reference distance and the degree of deviation from the scanning angle corresponding to the reference distance.

[0154] Calculate the difference between the scanning angle range of each object and the reference scanning angle range. If the difference is below the specified threshold, it is determined that it may be a target object. If the difference is above the specified threshold, it is determined that it is not a target object (S6, OK).

[0155] Next, for the object that was determined to be a potential target in step S6, the difference between the reflected light intensity distribution and the reference intensity distribution is calculated. If the difference is below a specified threshold, it is determined to be a target (S7, OK).

[0156] If the reference distance to the object being captured is determined to be below a preset proximity threshold (S8, Yes), then the information is sent to the driving control unit 70 (refer to...). Figure 8 It can output a deceleration or stop warning signal. It should be noted that it can also be configured to set the proximity threshold to two levels, outputting a deceleration warning signal when the threshold is below the larger threshold and an stop warning signal when the threshold is below the smaller threshold.

[0157] Additionally, in step S8, if the reference distance to the target object is greater than a preset proximity threshold and a deceleration or stop warning signal has been output in the past, the signal is deactivated. The above-described processes from steps S1 to S9 are repeated for each unit scan of the measurement light.

[0158] (Second embodiment of the object capturing device)

[0159] In the object capturing device 20 described above, the light-emitting unit 21 is composed of a laser diode with an infrared wavelength, but the wavelength is not particularly limited. Alternatively, the light-emitting unit may be configured to have multiple light sources with different wavelengths, as described above regarding the reference intensity distribution I. ref Each light source is determined separately according to its wavelength. There are no particular restrictions on the number of light sources or their wavelengths; appropriate settings are acceptable. The reference scanning angle range θ ref Same as above.

[0160] For example, the light-emitting part is composed of two light sources: a red laser diode chip and a green laser diode chip. If a reference intensity distribution corresponding to the spectral reflection characteristics of the reflector that becomes the reflector of the object being captured is set for each wavelength of the light source in a way that is different from the spectral reflection characteristics of the surface of the object being captured, the object being captured can be identified more reliably.

[0161] For example, the spectral reflectance characteristics of the reflector can be set to be the same as the reference intensity distributions for red and green, or they can be set to be different from the reference intensity distributions for red and green. Alternatively, the spectral reflectance characteristics for each color can be set to be continuously or progressively different along the scanning direction of the measurement light.

[0162] In this case, the light emission control unit 84 (refer to) Figure 8 The two light sources can be switched and driven alternately in a unit scan cycle of the light scanning unit 23. If the moving speed of the object being captured is sufficiently slow than a unit scan cycle of the light scanning unit 23, the light source can also be switched and driven for each unit scan cycle.

[0163] Alternatively, instead of having multiple light sources with different wavelengths in the light-emitting part 21 of an object capturing device 20, multiple object capturing devices 20 are prepared, each having a light-emitting part as a light source, and the light source wavelengths of the light-emitting parts of each object capturing device 20 are different.

[0164] Figure 14 Another example of the optical scanning unit 23 of the object capturing device 20 is shown. In the optical guiding unit 54 assembled in the optical scanning unit 23, opposite to the light emitting unit 21, the aforementioned polarizer PL is arranged at the entrance end of the measuring light path L, and the aforementioned detector polarizer AN is arranged at the exit end of the reflected light path L2 after being deflected by the deflecting mirror 52, rotating integrally with the deflecting mirror 52.

[0165] In Adoption Figure 7In the case of this structure, depending on the weight of the polarizer PL and the detector AN, the torque around the rotation axis 51 increases slightly, and the power of the motor 50 increases, but stable rotation of the optical scanning unit 23 can still be achieved. If using... Figure 14 With this structure, the power of motor 50 will not become Figure 7 The structure is so large.

[0166] Figure 15 Another example is shown, including the optical scanning unit 23 of the object capturing device 20. Figure 7 and Figure 14 In the example, a quarter-wavelength plate 28 is positioned immediately behind the projection lens 24 along the direction of light emission, but... Figure 15 In this example, a polarizer PL' for linearly polarizing light is disposed between the light-emitting part 21 and the quarter-wave plate 28. The polarizer PL is the first polarizer, and the polarizer PL' is the second polarizer.

[0167] By adjusting the polarizer PL' so that the polarizing surface of the incident light is incident at an azimuth angle of 45 degrees relative to the high-speed axis (or low-speed axis) of the quarter-wave plate 28, linearly polarized light can be changed into circularly polarized light that is close to a perfect circle. As a result, the measurement light after obtaining appropriately linearly polarized light is obtained using the polarizer PL provided in the light scanning unit 23.

[0168] Without the polarizer PL', when a resin lens with a high birefringence, such as polycarbonate, is used for the projection lens 24, the polarization state of the measurement light emitted from the laser diode, which becomes the light-emitting part 21, changes. Therefore, the measurement light after passing through the quarter-wave plate 28 becomes nearly elliptical circularly polarized light, and the measurement light after passing through the polarizer PL becomes elliptically polarized light, potentially reducing the detection accuracy of the reflected light. However, by providing the polarizer PL', the measurement light emitted from the laser diode is reliably linearly polarized and guided towards the quarter-wave plate 28. This ensures that the measurement light after passing through the polarizer PL is appropriately linearly polarized, thereby improving the detection accuracy of the reflected light.

[0169] Figure 16 Another example is shown, including the light scanning unit 23 of the object capturing device 20. On the exit side of the light guiding unit 54 assembled to the light scanning unit 23, a polarizer PL'' with the same polarization characteristics as the polarizer PL is arranged in the same tilted position as the deflector 52.

[0170] In the absence of a polarizer PL´´ and when the object illuminated by the measuring light is located near the object capturing device 20, the diameter of the beam of measuring light emitted from the light guide 54 is small, and the spread of the beam of reflected light from the object is also small. The diameter of the reflected light traveling in the reflected light path L2 is close to the diameter of the measuring light traveling in the measuring light path L1. As a result, the amount of light guided to the light receiving part 22 is reduced, which may lead to a situation where it is difficult to accurately detect the distance.

[0171] In this case, if a polarizer PL´´ is provided, the linearly polarized light in the reflected light from the object that is orthogonal to the linearly polarized light of the measurement light is reflected by the polarizer PL´´ and guided toward the light receiving part 22.

[0172] Therefore, if the object is the target object, the linearly polarized light orthogonal to the linearly polarized light of the measurement light is guided towards the light receiving unit 22, which can improve the detection accuracy. Furthermore, if the reflected light is the same linearly polarized light as the measurement light and the object is not the target object, the amount of reflected light guided towards the light receiving unit 22 is reduced after passing through the polarizer PL'', thus avoiding false detection. In other words, the polarizer PL'' functions as a semi-transparent mirror that guides the reflected light incident towards the light guiding unit 54 towards the light receiving unit 22. The polarizer PL'' can be appropriately placed within the measurement light path L1 if the reflected light can be guided towards the light receiving unit 22. Alternatively, a conventional semi-transparent mirror can sometimes be used.

[0173] (Filtering process to identify and capture objects based on the level of reflected light)

[0174] For the object discrimination unit 82 (refer to) Figure 8 The improvement of the object recognition algorithm is explained.

[0175] Figure 17 (a) shows the use of Figure 16 The detection characteristics of the object capturing device 20 with respect to the distance and light level of the reflected light relative to various reflective components. Figure 18 Show Figure 17 The material of each reflective component shown in (a). Figure 18 The “reflector” shown refers to a reflector attached to the object being captured and using the aforementioned optical components (e.g., a reflector using a trihedral corner reflector element).

[0176] Within a distance range of 50 to 1000 mm, the light-receiving level of the aforementioned reflector is significantly higher than that of other reflective components. When the distance exceeds 1000 mm, the light-receiving level of the reflector decreases considerably, but remains higher than that of other reflective components.

[0177] Therefore, by setting a threshold for the light reception level of reflected light corresponding to the distance, reflected light exceeding the threshold can be identified as the actual target object. In other words, by setting different threshold values ​​for the light reception level of reflected light based on the detection distance, it is possible to distinguish the target object from other objects.

[0178] Specifically, the threshold for the light reception level of reflected light from near distances is set to be larger than the threshold for the light reception level of reflected light from far distances. In the example above, the boundary between near and far distances is approximately 1000mm. For near distances within 1000mm, the threshold is set to 1000, and for far distances greater than 1000mm, the threshold is set to 700.

[0179] It should be noted that the boundary between near and far distances can be determined as an appropriate value based on the specific structure of the object capturing device 20, such as the amount of light from the light source, the sensitivity of the light-receiving element, and the structure of the optical system. Alternatively, it can be configured such that the threshold is set to different values ​​at each boundary between near, medium, and far distances, and the threshold can be switched at multiple levels.

[0180] Furthermore, the threshold setting for switching the level of reflected light based on the detection distance from the object is not limited to... Figure 16 The object capture device 20 with the structure shown only becomes effective after this. Figure 7 , Figure 14 , Figure 15 The object capturing device 20 with the structure shown can also be effectively applied.

[0181] Figure 17 (b) shows the detection characteristics of reflected light when the angle θ1 between the optical axis of the measuring light and the normal of the reflector varies within the range of 0° ± 45°. It exhibits a tendency to reach the maximum light level at an angle θ1 of 0° and the minimum near ± 45°. Since the light level becomes below the near-range threshold of 1000 near an angle θ1 of ± 45°, it may be undetectable near an angle θ1 of 45° on the reflector.

[0182] Figure 17 (c) shows the level of light received relative to the various reflective elements when the scanning direction is set to 0 degrees along the angle θ1. Figure 17 In step (c), step (STEP) 540 is to determine the light reception level when the scanning direction of the light is the normal direction of the reflective member. It should be noted that the distance between the reflective member and the object capturing device 20 is 500 mm. If the threshold for the light reception level is set to 1000, the reflector and other reflective members can be clearly identified.

[0183] Figure 17(d) shows the light reception level of the reflected light relative to the reflector along the scanning direction when the angle θ1 is set to 0 degrees, -45 degrees, and +45 degrees. The distance between the reflector and the object capturing device 20 is 500 mm. Figure 17 Similarly, in (b), if the threshold for the light level is set to 1000, which is the threshold for near-field use, it may be impossible to detect near an angle θ1 of ±45 degrees. In such a case, if a second threshold for near-field use is set to a level smaller than the threshold for near-field use, for example, if this value is set to 700, it can be reliably detected near an angle θ1 of ±45 degrees.

[0184] However, if the second threshold for close-range applications is set to 700, then as Figure 17 As shown in (a), when the angle θ1 is near 0 degrees, it is possible to misdetect a mirror-reflecting component such as an aluminum plate or a SUS plate as a reflector for capturing an object.

[0185] In this case, if the number of consecutive detection steps of reflected light relative to the scanning direction of the measuring light is taken into account, it is possible to identify reflected light from the specular reflection member and reflected light from the reflector (e.g., a reflector using a trihedral corner reflector element).

[0186] For example, such as Figure 17 As shown in (c), when the angle θ1 is 0 degrees, the second threshold 700 for close range is set to a threshold number greater than the number of consecutive detection steps of the reflected light from the detected mirror reflective member. When the light reception level of the reflected light continuously exceeds the second threshold 700 for close range by a number of steps greater than the threshold number, it can be identified as a capture object equipped with the reflector.

[0187] For example, when the detection distance is close, if either the condition that the light level of the reflected light is above a threshold for close distance or the condition that the light level of the reflected light is continuously above a second threshold for close distance for a number of steps above a threshold step, it can be identified as a target object.

[0188] In addition, when the detection distance is long distance, a second threshold for long distance is set at a level lower than the threshold for long distance. If either the light level of the reflected light is above the threshold for long distance or the light level of the reflected light is continuously above the second threshold for long distance for a number of steps above the threshold step, it can be identified as a target object.

[0189] (Other embodiments of the optical scanning unit assembled in the object capture device)

[0190] exist Figure 7In the object capturing device 20 shown, an example of a light scanning unit 23 consisting of a motor 50 provided on the inner wall of the upper surface of the upper housing 20B and a deflection mirror 52 fixed on the rotation shaft 51 of the motor 50 so as to be able to rotate integrally with the rotation shaft 51 has been described. However, the structure of the light scanning unit of the object capturing device to which the present invention is applicable is not limited to the structure described above, and other known structures of light scanning units can also be used.

[0191] For example, instead of the deflecting mirror described above, a rotating multifaceted mirror is configured to use a multifaceted prism whose sides are formed as mirrors and rotates around the longitudinal axis, so that the measuring light emitted from the light-emitting part scans toward the measuring object space and guides the reflected light toward the light-receiving part.

[0192] Alternatively, instead of the scanning mechanism that rotates the flat deflector described above, a swinging mechanism that performs swing scanning can be used. Furthermore, it can be configured to include a swinging mechanism that drives the deflector, driven by the optical scanning unit 23 to rotate, to perform swing scanning around an axis intersecting the rotation axis, thereby enabling three-dimensional scanning.

[0193] Regardless of the method, as long as the optical scanning unit has a deflecting mirror and an optical guiding unit that divides the optical path for guiding the measurement light deflected by the deflecting mirror to the measurement object space and the optical path for guiding the reflected light to the light receiving unit, the polarizer is arranged on the measurement light optical path side of the optical guiding unit, and the polarizer is arranged on the reflected light optical path side of the optical guiding unit.

[0194] With such a structure, the optical path is divided into a measurement optical path and a reflected optical path by the light guiding section. When the measurement light emitted from the light-emitting section travels along the measurement optical path, only linearly polarized light vibrating along the first direction passes through the polarizer and scans into the measurement object space. When the reflected light from the object travels along the reflected optical path, only linearly polarized light vibrating along the second direction orthogonal to the first direction passes through the polarizer and is received by the light receiving section.

[0195] (Signal processing to reduce the influence of interference light from other object-capturing devices)

[0196] When measurement light from another object capturing device 20 located near the object capturing device 20 is incident as interference light, it may be falsely detected as reflected light relative to the measurement light emitted from that object capturing device 20. When the measurement light emitted from both object capturing devices 20 has the same period, the possibility of false detection increases because the interference light is incident with the same period.

[0197] Therefore, the light emission control unit 84 (refer to) Figure 8The device is configured such that the average period of the measuring light emitted from each object capturing device 20 is kept constant, and the emission periods are randomly staggered within a range of T / 2 periods before and after the average period T, thereby avoiding the phenomenon that interference light is incident with the same period.

[0198] Furthermore, when detecting multiple reflected lights relative to the measuring light emitted from the object capturing device 20 with respect to a single pulse of measuring light, it is preferable to use the distance calculation unit 81 (see reference 81) to perform the calculation. Figure 8 The system is configured to perform a process on a continuous set number of measurement lights, dividing the period T of the measurement light into multiple time regions and storing information in a memory about which time region the detected reflected light belongs to, and using the reflected light of the time region with the largest number of detected reflected light as the true reflected light.

[0199] Similarly, when detecting multiple reflected lights relative to the measuring light emitted from the object capturing device 20, it is also possible to configure the device to use the distance calculation unit 81 (see reference 81). Figure 8 ) calculate the distance relative to each reflected light, and then use the object discrimination unit 82 (refer to Figure 8 The system is configured to perform a process on a continuous set number of measurement lights, dividing the period T of the measurement light into multiple time regions and storing information in a memory which time region the detected distance belongs to, and using the number of detected distances as the distance of the time region with the largest time region as the distance relative to the true reflected light.

[0200] Furthermore, in the case where multiple reflected lights are detected relative to the measuring light emitted from the object capturing device 20, the distance calculation unit 81 (see reference) may also be used. Figure 8 The system is configured to perform a process that divides the period T of the measured light into multiple time regions and stores information in memory which time region the detected reflected light belongs to, across a specified number of scan cycles, and uses the distance of the time region with the largest number of detected reflected light as the distance relative to the true reflected light.

[0201] Similarly, when detecting multiple reflected lights relative to the measuring light emitted from the object capturing device 20, it is also possible to configure the device to use the distance calculation unit 81 (see reference 81). Figure 8 ) calculate the distance relative to each reflected light, and then use the object discrimination unit 82 (refer to Figure 8 The system is configured to perform a process that divides the period T of the measured light into multiple time regions and stores information about which time region the detected distance belongs to in a memory, and uses the number of detected distances as the distance of the time region with the largest time region as the distance relative to the true reflected light.

[0202] (Capture the reflective surface of the object)

[0203] Preferably, the object captured by the object capturing device 20 described above has a reflective sheet 40, and the reflective sheet 40 has a reflective characteristic in which the amount of reflected light changes in stages along the scanning direction of the measuring light scanned by the light scanning unit 23.

[0204] By setting the reflective properties of the object's reflective surface to vary the amount of reflected light in stages or continuously along the scanning direction of the measurement light scanned by the light scanning unit 23, high-precision identification with other objects that do not possess such properties can be achieved.

[0205] For example, such as Figure 19 As shown in (a), if the surface reflectivity of the reflector 40 is set higher at both ends and the center along the scanning direction of the measuring light, and lower between both ends and the center, then the amount of reflected light detected by the light-receiving part 22 changes in stages along the scanning direction, so that it can be reliably identified as reflected light from other objects.

[0206] For example, such as Figure 19 As shown in (b), if the surface reflectivity of the reflector 40 is set to vary in a sawtooth pattern along the scanning direction of the measuring light, the amount of reflected light detected by the light-receiving part 22 will continuously increase or decrease along the scanning direction, thus enabling reliable identification as reflected light from other objects.

[0207] Alternatively, a reflective sheet 40 may be used, which has a reflective characteristic that changes periodically or continuously along the scanning direction of the measurement light relative to the wavelength of the measurement light. When the light-emitting unit 21 has multiple light sources with different wavelengths, it is preferable to have a reflective characteristic that changes for each wavelength of the light source.

[0208] In all cases, it is preferable to use a retroreflective element as the reflector 40, particularly a retroreflective element formed by arranging trihedral corner reflector elements on the surface. When using such a retroreflective element, the reflectors 41, 42, and 43 (see reference...) Figure 14 (a) Forms an interference film of a specified thickness, thereby enabling adjustment of the spectral reflection characteristics.

[0209] Alternatively, instead of arranging a retroreflective element over the entire area of ​​the reflector 40, the area can be divided into regions with retroreflective elements and regions without retroreflective elements, with the amount of reflected light varying in stages or continuously along the scanning direction of the measuring light. For example, diffuse reflection elements or light-absorbing elements can be arranged in the regions without retroreflective elements.

[0210] By appropriately combining the object capturing device 20 of the above-described various methods and the reflective sheet 40 provided with the object to be captured, the object capturing system of the present invention can be embodied.

[0211] The embodiments described above are merely one example of the present invention. The scope of the present invention is not limited by this description. It is self-evident that the specific structure of each part can be appropriately changed within the scope of achieving the effects of the present invention.

Claims

1. An object capturing device, which is an object capturing device for capturing objects existing in a measurement object space, wherein, The object capturing device includes: Light-emitting part; Light-receiving part; as well as The optical scanning unit scans a predetermined wavelength of measurement light emitted from the light-emitting unit toward the measurement object space, and guides reflected light from objects in the measurement object space toward the light-receiving unit. The optical scanning unit includes a optical guiding unit, which divides the optical path that guides the measurement light, which has been deflected by the deflecting mirror, toward the measurement object space and the optical path that guides the reflected light toward the light receiving unit. A semi-transparent lens is disposed on the light path side of the light guide portion to guide the reflected light toward the light receiving portion.

2. The object capturing device according to claim 1, wherein, The object capturing device has a housing. The portion of the housing that forms the path for the measuring light and the reflected light is made of a raw material that allows the measuring light to pass through and has low polarization characteristics relative to the measuring light.

3. The object capturing device according to claim 1, wherein, The light-emitting part has multiple light sources with different wavelengths, and these multiple light sources with different wavelengths are switched and driven synchronously with the scanning cycle of the light scanning part.

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