JP2016080534A - Projection device and parallax acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection device capable of more increasing power efficiency and a parallax acquisition device.SOLUTION: The projection device is the projection device for projecting pattern light onto an imaged specimen and includes a light source for emitting light not including a wavelength longer than a wavelength whose relative luminous efficiency is highest, a light condensing optical system for condensing the light, a formation part illuminated by the condensing optical system, to form the pattern light, and a projection optical system for projecting the pattern light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projection device and a parallax acquisition device.

  There is already known a technique in which a test object on which pattern light is projected is captured by a stereo camera, and distance information from the captured image to the test object is acquired by so-called stereo distance measurement. In this stereo ranging, the distance to the test object is calculated based on the principle of triangulation using the parallax of the subject generated between two images. Even if the test object has no features such as shading and pattern, the pattern light representing the random pattern etc. is projected onto the test object, so that the corresponding points between the two images become clear, so-called stereo ranging is performed. The distance information to the test object can be acquired.

  Patent Document 1 discloses an invention of a random pattern generation apparatus that can determine the suitability of a projection pattern image for distance measurement and generate a highly accurate distance image. Patent Document 2 discloses an invention of a light projection pattern generation apparatus that realizes generation of a more appropriate pattern as a pattern to be projected onto a measurement target.

  However, when it is difficult to image a test object such as a black test object, if the output of the light source is increased in order to improve the imaging accuracy, there is a problem that the power consumption increases and the running cost of the apparatus increases.

  The present invention has been made in view of the above, and an object thereof is to provide a projection device and a parallax acquisition device that can further improve power efficiency.

  In order to solve the above-described problems and achieve the object, the present invention is a projection device that projects pattern light onto an object to be imaged, and does not include a wavelength longer than the wavelength having the highest relative visibility. A light source that emits light, a condensing optical system that condenses the light, a forming unit that forms pattern light by being illuminated by the condensing optical system, a projection optical system that projects the pattern light, Is provided.

  According to the present invention, there is an effect that the power efficiency can be further improved.

FIG. 1 is a diagram illustrating an example of the configuration of the projection apparatus according to the first embodiment. FIG. 2 is a graph showing the relationship between the wavelength of light and the Y stimulus value. FIG. 3 is a diagram illustrating an example of the configuration of the parallax acquisition device according to the second embodiment. FIG. 4 is a diagram illustrating an example of the configuration of the projection apparatus according to the second embodiment. FIG. 5 is a diagram showing an example of the configuration of the reflection diffusion plate of the second embodiment. FIG. 6 is a diagram illustrating an example of the configuration of the stereo camera of the second embodiment.

  Hereinafter, embodiments of a projection device and a parallax acquisition device will be described in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a diagram illustrating an example of a configuration of a projection apparatus 100 according to the first embodiment. A projection apparatus 100 according to the first embodiment includes a light source 1, a condensing element 2, a condensing element 3, a forming unit 4, and a projection optical system 5. The projection device 100 projects light onto a test object arranged on the projection surface 6.

  The light source 1 is a solid light source such as a light emitting diode (LED) or a semiconductor laser (LD). A light emitting diode moves electrons and holes by current injection, and when electrons and holes are bonded at the junction (junction) between a P-type semiconductor and an N-type semiconductor, It is a solid light source that emits as A semiconductor laser is a solid-state light source that uses the principle of laser oscillation that amplifies the amount of light like an avalanche by causing stimulated emission one after another from the light emitted first by electrons injected into a narrow area of the junction It is. The solid light source converts the injected current (electrons) into light energy, so that very efficient light output is possible.

  Here, the relationship among the wavelength of light, specific luminous efficiency, and light energy will be described.

  FIG. 2 is a graph showing the relationship between the wavelength of light and the Y stimulus value. The human eye has a specific visibility characteristic, and the sensitivity characteristic varies depending on the wavelength of light. The brightness per 1 W can be expressed as lm = 683 × Y stimulus value. The Y stimulus value (specific luminous sensitivity) takes a value in the range of 0 to 1 depending on the length of the wavelength. The larger the Y stimulus value, the higher the sensitivity and the brighter the human eye feels. The Y stimulation value takes the highest value (Y = 1.0) when the wavelength length is 555 nm.

  More specifically, the Y stimulus value is about Y = 0.03 to 0.06 in the blue region 101, about Y = 0.7 to 1.0 in the green region 102, and Y = 0.25 in the red region 103. ˜0.5. That is, the Y stimulus value is the highest in the green region 102, and the values in the red region 103 and the blue region 101 are two digits in the decimal point, and are one digit smaller than the Y stimulus values of other colors.

  However, although blue (purple) looks dark to human eyes, its light energy is high because of its short wavelength (high frequency). In other words, even if it is light that is not dazzling to human eyes, light with a short wavelength has a large light energy. For example, blue monochromatic light can provide a sufficient amount of light to a camera that uses a light sensor, an image sensor, and the like that receive light and convert the light energy into electric power. That is, if a pattern is projected with blue monochromatic light, even if the lumen value has a low luminous flux, higher power of light than other colors can be given to the image sensor. In other words, the blue monochromatic light can obtain a high light output according to the input electric power, and has high power efficiency.

  Examples of solid light source materials include GaAsP, GaP, AlGaAs, AlGaInP, and InGaN. The light emission color of the GaAsP-based material is vermilion-red (peak wavelength is 570 to 800 nm), and the light emission efficiency is 0.2 to 1.0 lm / W. The emission color of the GaP-based material is green (peak wavelength is 480-570 nm), and the emission efficiency is 2.0 to 3.0 lm / W. The emission color of the AlGaAs-based material is red (peak wavelength is 620-670 nm), and the light emission efficiency is 6-12 lm / W. The emission color of the AlGaInP-based material is vermilion-green (peak wavelength is 560-650 nm), and the light emission efficiency is 15-40 lm / W. The emission color of the InGaN-based material is blue-green (peak wavelength is 400-470 nm), and the light emission efficiency is 10-50 lm / W. When the optical output is converted into watts (W), the InGaN system has the highest power efficiency. Therefore, power efficiency can be improved by using an InGaN-based material for the solid-state light source.

  An illumination system used for a video projector needs to balance the brightness of R, G, and B in order to maintain white balance. However, when used for measurement of an object as in the projection apparatus 100 of the first embodiment, it is not particularly necessary to use full color, but rather it is efficient to use monochromatic light with high light utilization efficiency. . In addition, the blue monochromatic light has low visibility and is less dazzling than other colors by the human eye, but the imaging device can image the test object irradiated with the blue monochromatic light with high accuracy. .

  Returning to FIG. 1, the light source 1 is a solid-state light source that emits light that does not include a wavelength longer than the wavelength with the highest specific visibility. The light source 1 emits light having a peak wavelength in the range of 400 nm to 470 nm, for example. More specifically, the light source 1 emits blue monochromatic light (for example, light having a wavelength near 450 nm) using an InGaN-based solid light source. Thereby, the power efficiency of the projection apparatus 100 can be further improved.

  A condensing element (condensing lens) 2 and a condensing element (condensing lens) 3 are condensing optical systems. The condensing element 2 narrows the divergence angle by condensing the light emitted from the light source 1 as almost diffused light by a combination of a plurality of lenses, and inputs light of a certain luminous flux to the condensing element 2. To do. The condensing element 3 projects light onto an area necessary for illumination of the forming unit 4.

  The forming unit 4 is disposed at a position conjugate with the light source 1. Thereby, the light source 1 can perform illumination of the formation part 4 most efficiently. The forming unit 4 forms pattern light. Specifically, the formation unit 4 has a pattern including a reflection unit that reflects light that is not shown in FIG. 1 and a transmission unit that transmits light. The pattern is formed by, for example, an etching process. The transmission part has a predetermined transmittance. Further, the reflecting portion has a predetermined reflectance. A liquid crystal panel or a digital mirror device may be used for the forming portion 4. However, when it is not necessary to change the pattern, a fixed pattern that does not need to take into consideration a decrease in the transmittance of the liquid crystal panel, a decrease in the reflectance of the digital mirror device, and the like is optimal. Further, if the pattern is fixed, drive control is not necessary, so that the configuration is simple and the projection apparatus 100 can be downsized.

  The projection optical system 5 magnifies the pattern light at a predetermined magnification and projects it onto the projection surface 6 on which the test object is arranged.

  In the above-described configuration, a light tunnel may be further provided between the light collecting element 2 and the light collecting element 3. The light tunnel is configured by forming four reflecting surfaces in a columnar shape. The light condensed at the entrance of the light tunnel is reflected several times in the light tunnel, so that a plurality of apparent light sources are generated, and the effect of superimposing the light by the plurality of light sources can be obtained. By forming the exit position of the light tunnel and the illuminated formation portion 4 in a conjugate positional relationship, the formation portion 4 can be illuminated with uniform brightness.

  As described above, according to the projection device 100 of the first embodiment, the light source 1 projects light that does not include a wavelength longer than the wavelength having the highest relative visibility. Thereby, the power efficiency of the projection apparatus 100 can be further improved.

(Second Embodiment)
Next, a second embodiment will be described.

  FIG. 3 is a diagram illustrating an example of the configuration of the parallax acquisition device 200 according to the second embodiment. The parallax acquisition device 200 according to the second embodiment includes a projection device 300 and a stereo camera 400.

  First, an example of the configuration of the projection apparatus 300 will be described.

  FIG. 4 is a diagram illustrating an example of the configuration of the projection apparatus 300 according to the second embodiment. The projection apparatus 300 according to the second embodiment includes semiconductor lasers LD1 to LD8 (LD5 to LD8 are not shown), condenser lenses CL1 to CL8 (CL5 to CL8 are not shown), mirrors M1 to M4, and condenser lens 11. , A reflection diffusion plate 12, a tapered light tunnel 13, a forming unit 16, a triangular prism 17, and a projection optical system 18.

  Hereinafter, when the semiconductor lasers LD1 to LD8 are not distinguished, they are simply referred to as a semiconductor laser LD. Similarly, when the condenser lenses CL1 to CL8 are not distinguished, they are simply referred to as the condenser lens CL. Similarly, when the mirrors M1 to M4 are not distinguished, they are simply referred to as mirrors M.

  The semiconductor lasers LD1 to LD8 are arranged in two vertical rows and four horizontal rows. The upper stage is arranged in the order of semiconductor laser LD1, semiconductor laser LD2, semiconductor laser LD3, and semiconductor laser LD4, and the lower stage is arranged in order of semiconductor laser LD5, semiconductor laser LD6, semiconductor laser LD7, and semiconductor laser LD8. Each semiconductor laser LD is made of an InGaN-based material and emits blue monochromatic light at a constant divergence angle.

  Similarly, the condenser lenses CL1 to CL8 are arranged in two vertical rows and four horizontal rows. The upper row is arranged in the order of the condenser lens CL1, the condenser lens CL2, the condenser lens CL3, and the condenser lens CL4, and the lower row is arranged in the order of the condenser lens CL5, the condenser lens CL6, the condenser lens CL7, and the condenser lens CL8. Has been. Each condenser lens CL condenses the projected laser light and projects the laser light onto each mirror M as a substantially parallel light beam.

  Each mirror M projects the laser light onto the condenser lens 11 by bending the optical path of the projected laser light by 90 degrees. Specifically, the mirror M1 projects the laser light onto the condenser lens 11 by bending the optical path of the laser light projected by the semiconductor lasers LD1 and LD5 by 90 degrees. The mirror M2 projects the laser light onto the condenser lens 11 by bending the optical path of the laser light projected by the semiconductor lasers LD2 and LD6 by 90 degrees. The mirror M3 projects the laser light onto the condenser lens 11 by bending the optical path of the laser light projected by the semiconductor lasers LD3 and LD7 by 90 degrees. The mirror M4 projects the laser light onto the condenser lens 11 by bending the optical path of the laser light projected by the semiconductor lasers LD4 and LD8 by 90 degrees.

  The condensing lens 11 bundles eight laser beams of the semiconductor lasers LD1 to LD8 and collects them in the vicinity of the reflection diffusion plate 12. Here, the reflection diffusion plate 12 will be described.

  FIG. 5 is a diagram showing an example of the configuration of the reflective diffusion plate 12 of the second embodiment. The reflection diffusion plate 12 includes a diffusion surface 21 and a reflection surface 22. The diffusion surface 21 has a predetermined diffusion degree. The laser light incident on the diffusing surface 21 from the condenser lens 11 is diffused with a predetermined diffusivity and is incident on the reflecting surface 22. The reflection surface 22 reflects the laser light incident from the condenser lens 11 via the diffusion surface 21. The diffusing surface 21 again diffuses the laser light reflected by the reflecting surface 22 with a predetermined diffusivity. As a result, the reflection diffusing plate 12 bends the optical path of the laser light incident from the condenser lens 11 by approximately 90 degrees and emits the laser light to the tapered light tunnel 13. By using such a reflection diffusing plate 12, it becomes possible to pass the diffusing surface 21 twice with one component, and the diffusion effect can be further enhanced.

  Here, the reason for using the reflective diffusion plate 12 will be described. Laser light has high coherency, and so-called glare called speckle phenomenon occurs due to interference with each other. When the glare is a change in light emission intensity caused by temporal fluctuation, when the imaging time is instantaneous, the reading pattern changes depending on the time, and there is a problem that correct measurement cannot be performed. Therefore, by arranging the reflection diffusing plate 12 and uniformizing the fluctuation of the light emission distribution spatially and temporally, it is possible to read an accurate image.

  Returning to FIG. 4, the laser light is diffused and spreads to some extent by the reflection diffusion plate 12, but most of the laser light is taken into the tapered light tunnel 13. The tapered light tunnel 13 is composed of four mirrors (reflection surfaces). In FIG. 4, the reflecting surface 14 and the reflecting surface 15 are shown, but the remaining two mirrors (reflecting surfaces) are omitted. As shown in FIG. 4, the tapered light tunnel 13 has a larger outlet opening than the inlet. This is because the angle of the laser beam when entering is made gentle every time it is reflected inside the tapered light tunnel 13. That is, the spread angle of the laser beam is smaller at the exit of the tapered light tunnel 13 than at the entrance.

  The laser light emitted from the tapered light tunnel 13 irradiates the forming portion 16. Since the laser light emitted from the tapered light tunnel 13 diverges, the forming portion 16 is disposed at a position close to the exit of the tapered light tunnel 13. The formation part 16 has an irregular pattern. The formation part 16 forms pattern light by being irradiated with laser light emitted from the tapered light tunnel 13.

  The triangular prism 17 bends the optical path of the pattern light by 90 degrees and causes the pattern light to enter the projection optical system 18. The projection optical system 18 magnifies and projects the pattern light.

  Returning to FIG. 3, the projection apparatus 300 projects the pattern light 30 onto a predetermined projection area with the configuration of FIGS. 4 and 5 described above. The stereo camera 400 images the test object on which the pattern light 30 is projected, and acquires parallax information (and distance information).

  Here, an example of the configuration of the stereo camera 400 will be described.

  FIG. 6 is a diagram illustrating an example of the configuration of the stereo camera 400 according to the second embodiment. A stereo camera 400 according to the second embodiment includes a first camera 31, a second camera 32, a storage unit 33, an external I / F 34, a correction unit 35, and a calculation unit 36.

  The first camera 31 captures a test object and acquires a reference image. The second camera 32 captures a test object and acquires a comparative image. The first camera 31 and the second camera 32 are arranged in parallel so that their optical axes are parallel. The imaging timings of the first camera 31 and the second camera 32 are synchronized, and the same test object is imaged simultaneously.

  The storage unit 33 stores a reference image, a comparison image, an image correction parameter, and the like. The image correction parameter is a parameter used when the correction unit 35 described later corrects the distortion and the like of the reference image and the comparison image.

  The external I / F 34 is an interface for inputting / outputting data in the storage unit 33.

  The correction unit 35 reads the reference image, the comparison image, and the image correction parameter from the storage unit 33. The correction unit 35 corrects the reference image and the comparison image using an image correction formula corresponding to the image correction parameter. The image correction formula is a formula for correcting the reference image (comparison image) by converting the coordinates of the reference image (comparison image). For example, when the coordinates of the reference image (comparison image) are corrected by affine transformation, the image correction equation can be expressed by a matrix, so the image correction parameter is a matrix component. When correcting the coordinates of the reference image (comparison image) by non-linear conversion, the image correction parameter is, for example, a coefficient such as a polynomial representing the conversion. The correction unit 35 may correct either one of the reference image and the comparison image. That is, the image correction formula may be an image correction formula for correcting the other image on the basis of one of the images. The correction unit 35 inputs the corrected reference image and the corrected comparison image to the calculation unit 36.

  The calculation unit 36 calculates parallax information of the image of the test object from the reference image and the comparison image. Specifically, the calculation unit 36 searches for corresponding points in the corrected comparative image corresponding to the points in the corrected reference image, and acquires parallax information of the test object using so-called stereo distance measurement. And the calculation part 36 acquires the distance information to a test object based on parallax information.

  As described above, the projection apparatus 300 irradiates the specimen placed in the projection area with pattern light. Then, the stereo camera 400 captures the test object and acquires the reference image and the comparison image, whereby the corresponding points between the reference image and the comparison image are clarified, and so-called stereo ranging is used to detect the surface of the test object. Distance information indicating a three-dimensional shape can be acquired. At this time, since the pattern light is in the blue wavelength band, the wattage (W) as the quasi-physical quantity is high even if the lumen (lm) as the psychophysical quantity is low. Therefore, it is possible to provide sufficient light energy for imaging the test object by the stereo camera 400 and to further improve the power efficiency of the parallax acquisition device 200 (projection device 300).

  The semiconductor laser LD may be another solid-state light source such as a light emitting diode (LED), but the semiconductor laser LD is most preferable. This is because the semiconductor laser LD has a light emitting portion of several um, several tens of um, or several mm, which is sufficiently small with respect to the condensing optical system. Therefore, the semiconductor laser LD is easily arranged in parallel to the condenser lens. That is, even if the output of one semiconductor laser LD is small, a plurality of semiconductor lasers LD can be provided discretely. Therefore, the influence of mutual heat interference can be reduced, and higher light output can be obtained without lowering the light emission efficiency. Further, since the semiconductor laser LD is small, the projection apparatus 300 is not enlarged even if a plurality of semiconductor lasers are discretely arranged.

DESCRIPTION OF SYMBOLS 1 Light source 2 Condensing element 3 Condensing element 4 Formation part 5 Projection optical system 6 Projection surface 11 Condensing lens 12 Reflection diffuser plate 13 Tapered light tunnel 14 Reflection surface 15 Reflection surface 16 Formation part 17 Triangular prism 18 Projection optical system 21 Diffusion Surface 22 Reflecting surface 30 Pattern light 31 First camera 32 Second camera 33 Storage unit 34 External I / F
35 Correction Unit 36 Calculation Unit 100 Projection Device 200 Parallax Acquisition Device 300 Projection Device 400 Stereo Camera CL1 to CL8 Condensing Lens LD1 to LD8 Semiconductor Laser M1 to M4 Mirror

JP 2001-147110 A Japanese Patent Laid-Open No. 2007-017355

Claims (6)

A projection device that projects pattern light onto an object to be imaged,
A light source that emits light that does not include a wavelength longer than the wavelength with the highest specific visibility;
A condensing optical system for condensing the light;
A forming unit that forms pattern light by being illuminated by the condensing optical system;
A projection optical system for projecting the pattern light;
A projection apparatus comprising: The light source emits light having a peak wavelength of 400 nm to 470 nm;
The projection device according to claim 1. The light source is a solid light source in which an InGaN-based material is used.
The projection apparatus according to claim 1 or 2. The light source is at least one light emitting diode or at least one semiconductor laser;
The projection device according to any one of claims 1 to 3. Further comprising a reflection diffusion plate for allowing the light condensed by the condensing optical system to enter the forming portion;
The reflection diffusion plate is
A diffusion surface on which light collected by the condensing optical system is incident;
A reflecting surface that reflects the light incident from the diffusing surface and enters the diffusing surface again;
A projection apparatus according to claim 1, comprising: A parallax acquisition device comprising a projection device for projecting pattern light onto an object to be imaged, and a stereo camera,
The projection device
A light source that emits light that does not include a wavelength longer than the wavelength with the highest specific visibility;
A condensing optical system for condensing the light;
A forming unit that forms pattern light by being illuminated by the condensing optical system;
A projection optical system for projecting the pattern light,
The stereo camera
A first camera that captures the test object and obtains a reference image;
A second camera that images the test object and obtains a comparison image;
A calculation unit that calculates parallax information of the image of the test object from the reference image and the comparison image;
A parallax acquisition device comprising: