WO2013046928A1

WO2013046928A1 - Information acquiring device and object detecting device

Info

Publication number: WO2013046928A1
Application number: PCT/JP2012/069942
Authority: WO
Inventors: 武藤　裕之; 楳田　勝美; 山口　淳
Original assignee: 三洋電機株式会社
Priority date: 2011-09-29
Filing date: 2012-08-06
Publication date: 2013-04-04
Also published as: JP2014238262A

Abstract

An information acquiring unit and an object detecting unit are provided to detect the distance to a detected object with accuracy even when the dot pattern is changed during the measurement. The information acquiring device (1) includes projecting optics (100), light-receiving optics (200), memory (27) for holding reference templates based on reference images, and a distance acquiring unit (21b) for referencing the measured image and a reference template, and acquiring distance information based on the positional relationship between a segment area of the reference image and a comparative area of the measured image corresponding to the segment area. The memory holds various types of reference templates corresponding to the spatial spread of the dot pattern, and the distance acquiring unit selects the reference template to be used during the measurement from the various types of reference templates, and then acquires the distance information. In this way, the distance can be accurately measured even when the dot pattern changes.

Description

Information acquisition device and object detection device

The present invention relates to an object detection apparatus that detects an object in a target area based on a state of reflected light when light is projected onto the target area, and an information acquisition apparatus suitable for use in the object detection apparatus.

Conventionally, an object detection device using light has been developed in various fields. An object detection apparatus using a so-called distance image sensor can detect not only a planar image on a two-dimensional plane but also the shape and movement of the detection target object in the depth direction. In such an object detection device, light in a predetermined wavelength band is projected from a laser light source or LED (Light-Emitting-Diode) onto a target area, and the reflected light is received by a light-receiving element such as a CMOS image sensor. Various types of distance image sensors are known.

In a distance image sensor of a type that irradiates a target region with laser light having a predetermined dot pattern, reflected light from the target region of laser light having a dot pattern is received by a light receiving element. Then, based on the light receiving position of the dot on the light receiving element, the distance to each part of the detection target object (irradiation position of each dot on the detection target object) is detected using triangulation (for example, Patent Literature 1, Non-Patent Document 1).

JP 2011-169701 A

In the object detection apparatus, the projection optical system and the light receiving optical system are arranged side by side. In this case, the dot light receiving position on the image sensor is normally displaced only in the direction in which the projection optical system and the light receiving optical system are arranged. In the object detection device, the distance is detected based on the movement amount of the dots in the direction in which the projection optical system and the light receiving optical system are arranged.

In the object detection apparatus, a diffractive optical element is used to generate a dot pattern laser beam. The optical characteristics of the diffractive optical element depend on the wavelength of the laser light. On the other hand, the wavelength of the laser beam is likely to change according to the temperature change of the light source. For this reason, when the wavelength of the laser light changes due to a temperature change or the like, the dot pattern of the laser light can also change in a direction perpendicular to the alignment direction of the projection optical system and the light receiving optical system. Such a change in the dot pattern may occur due to a change in the diffractive optical element over time in addition to the wavelength variation of the laser light.

In such a case, if the movement of the dot is searched only in the direction in which the projection optical system and the light receiving optical system are arranged, the detection of the movement amount of the dot cannot be performed properly, and the detection accuracy of the distance to each part of the detection target object deteriorates. Problem arises.

The present invention has been made in view of this point, and there is provided an information acquisition device capable of appropriately detecting a distance to a detection target object even when a dot pattern changes during measurement, and an object detection device equipped with the information acquisition device. The purpose is to provide.

1st aspect of this invention is related with the information acquisition apparatus which acquires the information of a target area | region using light. The information acquisition apparatus according to this aspect is configured to project a laser beam emitted from a laser light source onto a target area with a predetermined dot pattern, and to be arranged laterally apart from the projection optical system by a predetermined distance. A light receiving optical system that images the target area with an image sensor, and a storage unit that holds reference information based on a reference dot pattern imaged by the light receiving optical system when the laser beam is irradiated onto a reference surface. , Referring to the measurement information based on the measurement dot pattern imaged by the image sensor at the time of measurement and the reference information, a reference area on the standard dot pattern, and an area on the measurement dot pattern corresponding to the reference area, A distance acquisition unit that acquires distance information with respect to the reference region based on the positional relationship. Here, the storage unit holds a plurality of types of the reference information corresponding to the extent of the dot pattern. The distance acquisition unit selects the reference information used at the time of actual measurement from among the plurality of types of reference information stored in the storage unit, and executes the acquisition of the distance information using the selected reference information.

The second aspect of the present invention relates to an object detection apparatus. The object detection apparatus according to this aspect includes the information acquisition apparatus according to the first aspect.

According to the present invention, it is possible to provide an information acquisition device and an object detection device that can appropriately detect the distance to a detection target object even when the dot pattern changes during actual measurement.

The effect or significance of the present invention will become more apparent from the following description of embodiments. However, the embodiment described below is merely an example when the present invention is implemented, and the present invention is not limited to the following embodiment.

It is a figure which shows the structure of the object detection apparatus which concerns on embodiment. It is a figure which shows the structure of the information acquisition apparatus and information processing apparatus which concern on embodiment. It is a perspective view which shows the external appearance of the projection optical system which concerns on embodiment, and a light-receiving optical system. It is a figure which shows the irradiation state of the laser beam with respect to the target area | region which concerns on embodiment, and the light reception state of the laser beam on an image sensor. It is a figure explaining the production | generation method of the reference pattern which concerns on embodiment. It is a figure explaining the distance detection method which concerns on embodiment. It is a figure explaining the method to hold | maintain a reference template according to the temperature change which concerns on embodiment. It is a figure which shows the flow at the time of the initial setting of the reference template which concerns on embodiment. It is a figure which shows the flow at the time of the initial setting of the reference template which concerns on embodiment. It is a figure which shows the flow at the time of the reset of the reference template which concerns on embodiment. It is a figure which shows the flow at the time of the reset of the reference template which concerns on embodiment. It is a figure which shows the example of distance matching when the temperature which concerns on embodiment changes. It is a figure explaining the method to hold | maintain a reference template according to the temperature change which concerns on the example 1 of a change. It is a figure explaining the method to detect the spreading condition of the dot pattern which concerns on the example 2 of a change.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, an information acquisition device of a type that irradiates a target area with laser light having a predetermined dot pattern is exemplified.

First, FIG. 1 shows a schematic configuration of the object detection apparatus according to the present embodiment. As illustrated, the object detection device includes an information acquisition device 1 and an information processing device 2. The television 3 is controlled by a signal from the information processing device 2.

The information acquisition device 1 projects infrared light over the entire target area and receives the reflected light with a CMOS image sensor, whereby the distance between each part of the object in the target area (hereinafter referred to as “three-dimensional distance information”). To get. The acquired three-dimensional distance information is sent to the information processing apparatus 2 via the cable 4.

The information processing apparatus 2 is, for example, a controller for TV control, a game machine, a personal computer, or the like. The information processing device 2 detects an object in the target area based on the three-dimensional distance information received from the information acquisition device 1, and controls the television 3 based on the detection result.

For example, the information processing apparatus 2 detects a person based on the received three-dimensional distance information and detects the movement of the person from the change in the three-dimensional distance information. For example, when the information processing device 2 is a television control controller, the information processing device 2 detects the person's gesture from the received three-dimensional distance information, and outputs a control signal to the television 3 in accordance with the gesture. The application program to be installed is installed. In this case, the user can cause the television 3 to execute a predetermined function such as channel switching or volume up / down by making a predetermined gesture while watching the television 3.

Further, for example, when the information processing device 2 is a game machine, the information processing device 2 detects the person's movement from the received three-dimensional distance information, and displays a character on the television screen according to the detected movement. An application program that operates and changes the game battle situation is installed. In this case, the user can experience a sense of realism in which he / she plays a game as a character on the television screen by making a predetermined movement while watching the television 3.

FIG. 2 is a diagram showing the configuration of the information acquisition device 1 and the information processing device 2.

The information acquisition apparatus 1 includes a projection optical system 100 and a light receiving optical system 200 as a configuration of an optical unit. The projection optical system 100 and the light receiving optical system 200 are arranged in the information acquisition apparatus 1 so as to be aligned in the X-axis direction.

The projection optical system 100 includes a laser light source 110, a collimator lens 120, a leakage mirror 130, a diffractive optical element (DOE: Diffractive Optical Element) 140, an FMD (Front Monitor Diode) 150, and a temperature sensor 160. Yes. The light receiving optical system 200 includes an aperture 210, an imaging lens 220, a filter 230, and a CMOS image sensor 240. In addition, the information acquisition apparatus 1 includes a CPU (Central Processing Unit) 21, a laser driving circuit 22, a PD signal processing circuit 23, a temperature detection circuit 24, an imaging signal processing circuit 25, An input / output circuit 26 and a memory 27 are provided.

The laser light source 110 is a single mode semiconductor laser that oscillates in a single longitudinal mode and stably outputs laser light in a certain wavelength band. The laser light source 110 outputs laser light in a narrow wavelength band having a wavelength of about 830 nm in a direction away from the light receiving optical system 200 (X-axis negative direction). The collimator lens 120 converts the laser light emitted from the laser light source 110 into light slightly spread from parallel light (hereinafter simply referred to as “parallel light”).

The leakage mirror 130 is composed of a multilayer film of dielectric thin films, and the number of layers and the thickness of the film are designed so that the reflectance is slightly lower than 100% and the transmittance is several steps smaller than the reflectance. The leakage mirror 130 reflects most of the laser light incident from the collimator lens 120 side in the direction toward the DOE 140 (Z-axis direction) and transmits the remaining part in the direction toward the FMD 150 (X-axis negative direction).

The DOE 140 has a diffraction pattern on the incident surface. Due to the diffractive action of this diffraction pattern, the laser light incident on the DOE 140 is converted into laser light having a predetermined dot pattern and irradiated onto the target area.

The diffraction pattern of the DOE 140 has, for example, a structure in which a step type diffraction hologram is formed in a predetermined pattern. The diffraction hologram is adjusted in pattern and pitch so as to convert the laser light converted into parallel light by the collimator lens 120 into laser light of a dot pattern.

The DOE 140 irradiates the target region with the laser beam incident from the leakage mirror 130 as a laser beam having a dot pattern that spreads radially. The size of each dot in the dot pattern depends on the beam size of the laser light when entering the DOE 140.

The FMD 150 receives the laser light transmitted through the leakage mirror 130 and outputs an electrical signal corresponding to the amount of light received.

The temperature sensor 160 detects the temperature around the laser light source 110 and outputs a signal corresponding to the temperature to the temperature detection circuit 24.

The laser light reflected from the target area enters the imaging lens 220 through the aperture 210.

The aperture 210 stops the light from the outside so as to match the F number of the imaging lens 220. The imaging lens 220 collects the light incident through the aperture 210 on the CMOS image sensor 240. The filter 230 is an IR filter (Infrared Filter) that transmits light in the infrared wavelength band including the emission wavelength (about 830 nm) of the laser light source 110 and cuts the wavelength band of visible light.

The CMOS image sensor 240 receives the light collected by the imaging lens 220 and outputs a signal (charge) corresponding to the amount of received light to the imaging signal processing circuit 25 for each pixel. Here, in the CMOS image sensor 240, the output speed of the signal is increased so that the signal (charge) of the pixel can be output to the imaging signal processing circuit 25 with high response from the light reception in each pixel.

The CPU 21 controls each unit according to a control program stored in the memory 27. With this control program, the CPU 21 is provided with the functions of a laser control unit 21a for controlling the laser light source 110 and a distance acquisition unit 21b for generating three-dimensional distance information.

The laser drive circuit 22 drives the laser light source 110 according to a control signal from the CPU 21. The PD signal processing circuit 23 amplifies and digitizes the voltage signal corresponding to the amount of received light output from the FMD 150 and outputs it to the CPU 21. Based on the signal supplied from the PD signal processing circuit 23, the CPU 21 determines to amplify or decrease the light amount of the laser light source 110 by processing by the laser control unit 21a. When it is determined that the light amount of the laser light source 110 needs to be changed, the laser control unit 21 a transmits a control signal for changing the light emission amount of the laser light source 110 to the laser driving circuit 22. Thereby, the power of the laser beam emitted from the laser light source 110 is controlled to be substantially constant.

The temperature detection circuit 24 digitizes a signal corresponding to the temperature output from the temperature sensor 160 and outputs it to the CPU 21. In the present embodiment, the temperature detection circuit 24 outputs the detected temperature in units of 0.2 ° C. The CPU 21 detects the emission wavelength variation of the laser light source 110 based on the signal supplied from the temperature detection circuit 24, and replaces the reference template for distance detection as will be described later. Note that the reference template replacement process according to the temperature change will be described later with reference to FIGS.

The imaging signal processing circuit 25 controls the CMOS image sensor 240 and sequentially takes in the signal (charge) of each pixel generated by the CMOS image sensor 240 for each line. Then, the captured signals are sequentially output to the CPU 21. Based on the signal (imaging signal) supplied from the imaging signal processing circuit 25, the CPU 21 calculates the distance from the information acquisition device 1 to each part of the detection target by processing by the distance acquisition unit 21b. The input / output circuit 26 controls data communication with the information processing apparatus 2.

The information processing apparatus 2 includes a CPU 31, an input / output circuit 32, and a memory 33. In addition to the configuration shown in the figure, the information processing apparatus 2 has a configuration for performing communication with the television 3 and for reading information stored in an external memory such as a CD-ROM and installing it in the memory 33. However, the configuration of these peripheral circuits is not shown for the sake of convenience.

The CPU 31 controls each unit according to a control program (application program) stored in the memory 33. With such a control program, the CPU 31 is provided with the function of the object detection unit 31a for detecting an object in the image. Such a control program is read from a CD-ROM by a drive device (not shown) and installed in the memory 33, for example.

For example, when the control program is a game program, the object detection unit 31a detects a person in the image and its movement from the three-dimensional distance information supplied from the information acquisition device 1. Then, a process for operating the character on the television screen according to the detected movement is executed by the control program.

When the control program is a program for controlling the function of the television 3, the object detection unit 31 a detects a person in the image and its movement (gesture) from the three-dimensional distance information supplied from the information acquisition device 1. To do. Then, processing for controlling functions (channel switching, volume adjustment, etc.) of the television 3 is executed by the control program in accordance with the detected movement (gesture).

The input / output circuit 32 controls data communication with the information acquisition device 1.

FIG. 3 is a perspective view showing an installation state of the projection optical system 100 and the light receiving optical system 200.

The projection optical system 100 and the light receiving optical system 200 are disposed on the base plate 300. The optical members constituting the projection optical system 100 are installed in the housing 100a, and the housing 100a is installed on the base plate 300. Thereby, the projection optical system 100 is arranged on the base plate 300.

Reference numerals

150a and 240a denote FPCs (flexible printed circuit boards) for supplying signals from the FMD 150, the temperature sensor 160, and the CMOS image sensor 240 to a circuit board (not shown), respectively.

The optical member constituting the light receiving optical system 200 is installed in the holder 200a, and this holder 200a is attached to the base plate 300 from the back surface of the base plate 300. As a result, the light receiving optical system 200 is disposed on the base plate 300. In the light receiving optical system 200, since optical members are arranged in the Z-axis direction, the height in the Z-axis direction is higher than that of the projection optical system 100. In the base plate 300, in order to suppress the height in the Z-axis direction, the periphery of the arrangement position of the light receiving optical system 200 is raised by one step in the Z-axis direction.

3, the positions of the exit pupil of the projection optical system 100 and the entrance pupil of the light receiving optical system 200 substantially coincide with each other in the Z-axis direction. Further, the projection optical system 100 and the light receiving optical system 200 are arranged with a predetermined distance in the X-axis direction so that the projection center of the projection optical system 100 and the imaging center of the light-receiving optical system 200 are aligned on a straight line parallel to the X axis. Installed at.

The installation interval between the projection optical system 100 and the light receiving optical system 200 is set according to the distance between the information acquisition device 1 and the reference plane of the target area. The distance between the reference plane and the information acquisition device 1 varies depending on how far away the target is to be detected. The closer the distance to the target to be detected is, the narrower the installation interval between the projection optical system 100 and the light receiving optical system 200 is. Conversely, as the distance to the target to be detected increases, the installation interval between the projection optical system 100 and the light receiving optical system 200 increases.

FIG. 4A is a diagram schematically showing the irradiation state of the laser light on the target region, and FIG. 4B is a diagram schematically showing the light receiving state of the laser light in the CMOS image sensor 240. FIG. For the sake of convenience, FIG. 5B shows a flat surface (screen) in the target area and a light receiving state when a person is present in front of the screen.

As shown in FIG. 4A, the projection optical system 100 irradiates a target region with laser light having a dot pattern (hereinafter, the entire laser light having this pattern is referred to as “DP light”). . In FIG. 4A, the luminous flux region of DP light is indicated by a solid line frame. In the light flux of DP light, dot regions (hereinafter simply referred to as “dots”) in which the intensity of the laser light is increased by the diffraction action by the DOE 140 are scattered according to the dot pattern by the diffraction action by the DOE 140.

If there is a flat surface (screen) in the target area, the DP light reflected thereby is distributed on the CMOS image sensor 240 as shown in FIG.

In FIG. 4B, the entire DP light receiving area on the CMOS image sensor 240 is indicated by a dashed frame, and the DP light receiving area incident on the imaging effective area of the CMOS image sensor 240 is indicated by a solid frame. Has been. The effective imaging area of the CMOS image sensor 240 is an area where the CMOS image sensor 240 receives a DP light and outputs a signal as a sensor, and has a size of, for example, VGA (horizontal 640 pixels × vertical 480 pixels). . Further, the light of Dt0 on the target area shown in FIG. 10A enters the position of Dt′0 shown in FIG. An image of a person in front of the screen is taken upside down on the CMOS image sensor 240 in the vertical and horizontal directions.

Here, the distance detection method will be described with reference to FIGS.

FIG. 5 is a diagram for explaining a reference pattern setting method used in the distance detection method.

As shown in FIG. 5A, a flat reflection plane RS perpendicular to the Z-axis direction is disposed at a position at a predetermined distance Ls from the projection optical system 100. The emitted DP light is reflected by the reflection plane RS and enters the CMOS image sensor 240 of the light receiving optical system 200. Thereby, an electrical signal for each pixel in the effective imaging area is output from the CMOS image sensor 240. The output electric signal value (pixel value) for each pixel is developed on the memory 27 in FIG.

Hereinafter, an image including all pixel values obtained by reflection from the reflection surface RS is referred to as a “reference image”, and the reflection surface RS is referred to as a “reference surface”. Then, as shown in FIG. 5B, a “reference pattern region” is set on the standard image. FIG. 5B shows a state in which the light receiving surface is seen through in the positive direction of the Z axis from the back side of the CMOS image sensor 240. The same applies to the drawings after FIG.

A plurality of segment areas having a predetermined size are set for the reference pattern area thus set. The size of the segment area is determined in consideration of the contour extraction accuracy of the object based on the obtained distance information, the load of the calculation amount of distance detection for the CPU 21, and the error occurrence rate by the distance detection method described later. In the present embodiment, the size of the segment area is set to 15 horizontal pixels × 15 vertical pixels.

Referring to FIG. 5C, the segment area set in the reference pattern area will be described. In FIG. 5C, for the sake of convenience, the size of each segment area is indicated by 7 pixels wide by 7 pixels high, and the center pixel of each segment area is indicated by a cross.

As shown in FIG. 5C, the segment areas are set so that adjacent segment areas are arranged at intervals of one pixel in the X-axis direction and the Y-axis direction with respect to the reference pattern area. That is, a certain segment area is set at a position shifted by one pixel with respect to a segment area adjacent to the segment area in the X-axis direction and the Y-axis direction. At this time, each segment area is dotted with dots in a unique pattern. Therefore, the pattern of pixel values in the segment area is different for each segment area. The smaller the interval between adjacent segment areas, the greater the number of segment areas included in the reference pattern area, and the resolution of distance detection in the in-plane direction (XY plane direction) of the target area is enhanced.

Thus, information on the position of the reference pattern area on the CMOS image sensor 240, pixel values (reference patterns) of all pixels included in the reference pattern area, and segment area information set for the reference pattern area are shown in FIG. 2 memory 27. These pieces of information stored in the memory 27 are hereinafter referred to as “reference templates”.

2 refers to the reference template when calculating the distance from the projection optical system 100 to each part of the detection target object. When calculating the distance, the CPU 21 calculates the distance to each part of the object based on the shift amount of the dot pattern in each segment area obtained from the reference template.

For example, as shown in FIG. 5A, when an object is present at a position closer than the distance Ls, DP light (DPn) corresponding to a predetermined segment area Sn on the reference pattern is reflected by the object, and the segment area Sn. It is incident on a different region Sn ′. Since the projection optical system 100 and the light receiving optical system 200 are adjacent to each other in the X-axis direction, the displacement direction of the region Sn ′ with respect to the segment region Sn is parallel to the X-axis. In the case of FIG. 5A, since the object is at a position closer than the distance Ls, the region Sn 'is displaced in the positive direction of the X axis with respect to the segment region Sn. If the object is at a position farther than the distance Ls, the region Sn ′ is displaced in the negative X-axis direction with respect to the segment region Sn.

Based on the displacement direction and displacement amount of the region Sn ′ with respect to the segment region Sn, the distance Lr from the projection optical system 100 to the portion of the object irradiated with DP light (DPn) is triangulated using the distance Ls. Calculated based on Similarly, the distance from the projection optical system 100 is calculated for the part of the object corresponding to another segment area. The details of such a calculation method are described in, for example, Non-Patent Document 1 (The 19th Annual Conference of the Robotics Society of Japan (September 18-20, 2001), Proceedings, P1279-1280).

In this distance calculation, it is detected to which position the segment region Sn of the reference template has been displaced at the time of actual measurement. This detection is performed by collating the dot pattern obtained from the DP light irradiated onto the CMOS image sensor 240 at the time of actual measurement with the dot pattern included in the segment region Sn. Hereinafter, an image made up of all the pixel values obtained from the DP light irradiated to the imaging effective area on the CMOS image sensor 240 at the time of actual measurement will be referred to as “measured image”. The effective imaging area of the CMOS image sensor 240 at the time of actual measurement is, for example, the size of VGA (horizontal 640 pixels × vertical 480 pixels), as in the case of acquiring the reference image.

FIGS. 6A to 6E are diagrams for explaining such a distance detection method. FIG. 6A is a diagram showing a reference pattern region set in a standard image on the CMOS image sensor 240, and FIG. 6B is a diagram showing an actually measured image on the CMOS image sensor 240 at the time of actual measurement. FIGS. 6C to 6E are diagrams for explaining a method for collating the dot pattern of the DP light included in the actual measurement image and the dot pattern included in the segment area of the reference template. For convenience, FIGS. 6 (a) and 6 (b) show only a part of the segment areas, and FIGS. 6 (c) to 6 (e) show the size of each segment area. It is shown by pixel × 9 pixels vertically. In addition, in the actual measurement image of FIG. 6 (b), for convenience, as shown in FIG. 4 (b), there is a person in front of the reference plane as a detection target object, and the image of the person is reflected. It is shown.

When searching the displacement position at the time of actual measurement of the segment area Si in FIG. 6A, as shown in FIG. 6B, the search area Ri is set for the segment area Si on the actual measurement image. The search area Ri has a predetermined width in the X-axis direction. The segment area Si is sent one pixel at a time in the search area Ri in the X-axis direction, and the dot pattern of the segment area Si is compared with the dot pattern on the measured image at each feed position. Hereinafter, a region corresponding to each feed position on the actually measured image is referred to as a “comparison region”. A plurality of comparison areas having the same size as the segment area Si are set in the search area Ri, and the comparison areas adjacent in the X-axis direction are shifted by one pixel from each other.

The search area Ri is determined by the direction in which the detection target object is farther from the reference plane than the information acquisition device 1 and how much distance is in the detectable direction. In FIG. 6, a shift of x pixels in the X-axis positive direction from a position shifted by x pixels in the negative X-axis direction from the pixel position (center pixel position) on the measured image corresponding to the pixel position of the segment region Si on the reference image. The search area Ri is set so that the segment area Si is sent in the range (hereinafter referred to as “search range Li”). In the present embodiment, a range from a position shifted by −30 pixels from the center pixel position to a position shifted by 30 pixels is set as the search range Li.

While the segment area Si is fed pixel by pixel in the X axis direction in the comparison area, the degree of matching between the dot pattern of the segment area Si stored in the reference template and the dot pattern of the DP light of the measured image is obtained at each feed position. It is done. As described above, the segment area Si is sent only in the X-axis direction in the search area Ri as described above. Normally, the dot pattern of the segment area set by the reference template is a predetermined value in the X-axis direction at the time of actual measurement. This is because the displacement occurs only within the range.

At the time of actual measurement, depending on the position of the detection target object, the dot pattern corresponding to the segment area may protrude from the actual measurement image in the X-axis direction. For example, when a dot pattern corresponding to the segment area S1 on the negative X-axis side of the reference pattern area is reflected by an object at a distance farther than the reference plane, the dot pattern corresponding to the segment area S1 is X more than the measured image. Positioned in the negative axis direction. In this case, since the dot pattern corresponding to the segment area is not within the effective imaging area of the CMOS image sensor 240, the segment area cannot be properly matched. However, since it is possible to perform matching appropriately in areas other than the end segment areas, there is little influence on object distance detection.

In addition, when matching is performed appropriately for the end region, the effective imaging region of the CMOS image sensor 240 at the time of actual measurement may be made larger than the effective imaging region of the CMOS image sensor 240 at the time of acquiring the reference image. What can be used should be used. For example, when an effective imaging area is set with a size of VGA (horizontal 640 pixels × vertical 480 pixels) at the time of acquiring a reference image, 30 pixels in the X-axis positive direction and X-axis negative direction than that when actually measured. The effective imaging area is set by a size that is larger. As a result, the actually measured image becomes larger than the reference image, but matching can be appropriately performed for the end segment area.

When detecting the matching degree, first, the pixel value of each pixel in the reference pattern area and the pixel value of each pixel in each segment area of the actual measurement image are binarized and stored in the memory 27. For example, when the pixel values of the reference image and the actually measured image are 8-bit gradations, among the pixel values of 0 to 255, pixels that are equal to or greater than a predetermined threshold are pixels whose pixel value is 1 and pixels that are less than the predetermined threshold are pixels The value is converted to 0 and held in the memory 27. Thereafter, the similarity between the comparison region and the segment region Si is obtained. That is, the difference between the pixel value of each pixel in the segment area Si and the pixel value of the corresponding pixel in the comparison area is obtained. A value Rsad obtained by adding the obtained difference to all the pixels in the comparison region is acquired as a value indicating the similarity.

For example, as shown in FIG. 6C, when pixels of m columns × n rows are included in one segment area, the pixel values T (i, j) of the pixels of i columns and j rows of the segment area ) And the pixel value I (i, j) of the pixel in the comparison area i column and j row. Then, the difference is obtained for all the pixels in the segment area, and the value Rsad of the equation shown in FIG. 6C is obtained from the sum of the differences. The smaller the value Rsad, the higher the degree of similarity between the segment area and the comparison area.

Thus, as shown in FIG. 6D, the value Rsad is obtained for all the comparison areas of the search area Ri for the segment area Si. FIG. 6E is a graph schematically showing the value Rsad at each feed position in the search area Ri. When the value Rsad is obtained for all the comparison regions of the search region Ri for the segment region Si, first, the minimum value Bt1 is referred to from the obtained value Rsad. Next, the second smallest value Bt2 is referred to from the obtained value Rsad. If the position of the minimum value Bt1 and the second smallest value Bt2 is two pixels or more and the difference value Es is less than the threshold value, the search for the segment area Si is considered as an error. On the other hand, if the difference value Es is equal to or greater than the threshold value, the comparison area Ci corresponding to the minimum value Bt1 is determined as the movement area of the segment area Si. For example, as shown in FIG. 6D, the comparison area Ci corresponding to the segment area Si is in the positive direction of the X axis with respect to the pixel position Si0 on the measured image at the same position as the pixel position of the segment area Si on the reference image. It is detected at a position shifted by α pixels. This is because the dot pattern of the DP light on the measured image is displaced in the X-axis positive direction from the segment area Si0 on the reference image by a detection target object (person) that is present at a position closer to the reference plane. Note that as the size of the segment region Si increases, the uniqueness of the dot pattern included in the segment region Si increases and the error rate decreases. In the present embodiment, since the size of the segment region Si is set to 15 horizontal pixels × 15 vertical pixels, the distance detection usually does not cause an error, and matching can be performed appropriately.

Thus, when the displacement position of each segment region is searched from the dot pattern of DP light acquired at the time of actual measurement, detection corresponding to each segment region is performed by triangulation based on the displacement position as described above. The distance to the part of the target object is obtained.

In this way, the same segment area search is performed for all the segment areas from segment area S1 to segment area Sn.

Incidentally, as described above, the dot pattern usually shifts only in the X-axis direction on the light receiving surface of the CMOS image sensor 240 during actual measurement. However, when the emission wavelength of the laser light source 110 fluctuates, the dot pattern shifts from the center of the dot pattern region to the radiation due to the relationship between the pattern pitch configured in the DOE 140 and the optical aberration of the DOE 140 and the like. Furthermore, the wavelength of the laser beam is likely to change with temperature. Thus, the dot pattern can be shifted not only in the X-axis direction but also in the Y-axis direction. If the dot pattern deviates in the Y-axis direction, matching between the actually measured dot pattern and the dot pattern held in the reference template cannot be performed properly.

Therefore, in the present embodiment, a dot pattern is imaged at the wavelength of the laser beam corresponding to each temperature to obtain a plurality of reference images, and a reference template corresponding to each reference image is held in the memory 27 in advance. . Then, matching processing is executed using a reference template that is assumed to be appropriate according to the temperature change of the laser light source 110 at the time of actual measurement.

FIG. 7 is a diagram for explaining a method of holding a reference template according to a temperature change in the present embodiment.

FIG. 7A is a graph showing fluctuations in the emission wavelength of the laser light source 110 according to temperature changes. The horizontal axis represents the ambient temperature Tc of the laser light source 110, and the vertical axis represents the emission wavelength of the laser light source 110. The horizontal axis is scaled in increments of 0.2 ° C., as is the case with the fine detection temperature in the temperature detection circuit 24.

Referring to FIG. 7A, when the ambient environment temperature Tc is 20 ° C. to 21.4 ° C., the emission wavelength of the laser light is stable at about 834 nm. When the ambient environment temperature Tc reaches 21.6 ° C., the emission wavelength of the laser light changes to approximately 835 nm. This is because the ambient temperature Tc of the laser light source 110 changes, the element temperature of the laser light source 110 changes, and the oscillation mode jumps to the adjacent longitudinal mode due to the change in the resonator length and the change in the gain spectrum. This is because a so-called mode hopping phenomenon has occurred. After the mode hop occurs, the emission wavelength of the laser light is stable at about 835 nm.

Next, when the ambient environment temperature Tc reaches 24.8 ° C., a mode hop occurs in the same manner, and the emission wavelength of the laser light changes to approximately 836 nm. Thereafter, the emission wavelength of the laser light is stable at about 836 nm. Further, when the ambient environment temperature Tc reaches 29.8 ° C., a mode hop occurs, and the emission wavelength of the laser light changes to about 837 nm, and then stabilizes at about 837 nm.

As described above, in the single mode semiconductor laser, the wavelength of the laser beam does not continuously change according to the temperature change, but changes by about 1 nm at the timing when the mode hop occurs. Therefore, the dot pattern is shifted at the timing when the mode hop occurs.

FIG. 7B shows the reference template table RT1. The reference template table RT1 is stored in the memory 27 in advance. Note that, in the reference template table RT1 in FIG. 7B, only the reference templates in some temperature zones are shown for convenience.

In the reference template table RT1, a reference template acquired at a wavelength corresponding to the temperature zone is stored in association with the temperature zone. The reference pattern areas of the reference template corresponding to each temperature are set to the same size and the same position. In the temperature zone, the temperature of the interval at which the mode hop occurs twice as shown in FIG. 7A is set. Therefore, the wavelength of the laser beam is shifted by approximately 2 nm in the temperature zones adjacent to each other.

For example, when the temperature zone is 20 ° C. to 24.6 ° C., the dot pattern is irradiated in a state where the wavelength of the laser beam is approximately 834 nm (for example, temperature 21 ° C.), and the reference image is acquired. Then, a reference template Rb is generated based on the acquired standard image, and the generated reference template Rb is set as a reference template in the temperature range of 20 ° C. to 24.6 ° C. When the temperature zone is 24.8 ° C. to 31 ° C., the dot pattern is irradiated in a state where the wavelength of the laser light is approximately 836 nm (for example, temperature 27 ° C.), and a reference image is acquired. Then, a reference template Rc is generated based on the acquired standard image, and the generated reference template Rc is set as a reference template in the temperature range of 24.8 ° C. to 31 ° C. Similarly, with respect to other temperature zones, the dot pattern is irradiated in a state where the wavelength of the laser beam becomes the wavelength of each temperature zone, and reference templates (Ra, Rd,...) Are generated. Are set as reference templates for the corresponding temperature zones.

Note that the temperature zone is set at the interval at which the mode hop occurs twice in this manner, because the wavelength of the laser beam is shifted by approximately 2 nm, so that the dots of the dot pattern are formed on the light receiving surface of the CMOS image sensor 240. This is because it is assumed that the pixel is shifted by one pixel.

FIG. 7C is a diagram schematically showing the relationship between the DP light at each temperature and the reference pattern area of the reference template. In FIG. 7C, a reference pattern area of the reference templates Ra to Rd and a lower right corner area (6 horizontal pixels × 6 vertical pixels) of the reference pattern area are partially enlarged from the top. ing.

In the case of the reference template Rb, DP light of a predetermined dot pattern is captured in the lower right corner area of the reference pattern area, and four dots are included. Hereinafter, for the sake of convenience, the change of the dot pattern according to the temperature change will be described in the relative relationship from the reference template Rb.

In the case of the reference template Ra, in the region at the lower right corner of the reference pattern region, the wavelength of the laser light is shifted to the shorter wavelength side by 2 nm than in the case of the reference template Rb. The image is taken with one pixel shifted by −1 pixel in the positive X-axis direction. In this case, two dots that were outside the reference pattern area at the time of the reference template Rb enter the reference pattern area.

In the case of the reference template Rc, in the lower right corner region of the reference pattern region, the DP light becomes 1 pixel in the Y-axis positive direction by shifting the wavelength by 2 nm longer than in the case of the reference template Rb. Images are taken in a state shifted by one pixel in the positive direction of the X axis. In this case, the two dots at the end in the reference pattern area at the time of the reference template Rb deviate from the reference pattern area.

Further, in the case of the reference template Rd, the wavelength of the DP light is shifted by 2 pixels in the Y-axis positive direction in the lower right corner area of the reference pattern area by shifting the wavelength by 4 nm longer than in the case of the reference template Rb. Images are taken in a state of being shifted by two pixels in the positive direction of the X axis. In this case, the three dots at the end in the reference pattern area at the time of the reference template Rb are out of the reference pattern area.

In the reference pattern area at the bottom and the second stage from the bottom in FIG. 7C, the DP light is shifted in the Y-axis positive direction and the X-axis positive direction, so that a new dot is displayed from the upper left in the lower right corner area. However, for convenience, the entering dots are not shown.

As described above, when the dot pattern is shifted, the dot pattern included in the reference pattern region changes, and the dot pattern included in the segment region also changes.

In this way, by preparing a plurality of reference templates in accordance with the temperature change corresponding to the interval between two mode hops, a reference template can be prepared at least every time the dot pattern is shifted by one pixel or more. As described above, since the reference image and the actually measured image are matched in a binarized state, if they are shifted within one pixel in the Y-axis direction, matching can be performed normally. Therefore, in the present embodiment, since a plurality of reference templates are set in the reference template table RT1 at a temperature interval that causes a shift of one pixel or more, the memory is compared with a case where a reference template is set every time a mode hop occurs. 27 capacity can be suppressed.

FIG. 8 is a diagram showing a flow of processing at the time of initial setting of the reference template. The processing in FIG. 8 is performed by the distance acquisition unit 21b of the CPU 21 in FIG.

Referring to FIG. 8A, when the distance acquisition operation starts, the CPU 21 acquires the current temperature based on the signal output from the temperature sensor 160 (S101). Next, the CPU 21 acquires the reference template Rt of the temperature zone Wt corresponding to the acquired current temperature from the reference template table RT1, and measures the distance using this reference template Rt (S102). Furthermore, the CPU 21 acquires the ratio (matching error rate) Ert of the segment area in which the search is an error to the total segment area in the search of the segment area in the distance measurement (S103).

Thereafter, the CPU 21 performs distance measurement using reference templates respectively associated with m temperature zones before and after the temperature zone Wt in the reference template table RT1 (S104), and acquires a matching error rate in each measurement. (S105). Then, the CPU 21 sets the reference template corresponding to the minimum matching error rate among the matching error rate Ert acquired in S103 and the matching error rate acquired in S105 as a reference template for distance measurement (S106). Thereafter, the CPU 21 measures the distance using the reference template set in S106.

In FIG. 8A, the optimum reference template for the actual measurement is selected from the reference template in the temperature zone corresponding to the current temperature and the m reference templates before and after the temperature template. As described above, the reference template most suitable for actual measurement may be selected from all the reference templates held in the reference template table RT1. In FIG. 8B, the CPU 21 performs distance measurement using each reference template in the reference template table RT1 (S111), and acquires a matching error rate in each measurement (S112). And CPU21 sets the reference template corresponding to the minimum matching error rate among the acquired matching error rates to the reference template for distance measurement (S113).

In the process of FIG. 8B, since the reference template that is optimal for actual measurement is selected from all the reference templates held in the reference template table RT1, it is more optimal than the case of FIG. 8A. The probability that a simple reference template is set as a reference template for actual measurement increases. However, since it is necessary to measure the distance and acquire the matching error rate for all the reference templates, the time required for the processing at the initial setting becomes long. On the other hand, according to the process of FIG. 8A, since the reference template is selected by narrowing down the range of the reference template that can be optimized, the optimal reference is made while suppressing the lengthening of the process at the initial setting. A template can be efficiently set as a reference template used for measurement.

FIG. 9A is a diagram showing another initial setting process. When the distance measurement operation starts, the CPU 21 acquires the current temperature (S121). Then, the CPU 21 sets a reference template in a temperature zone corresponding to the current temperature among the reference templates held in the reference template table RT1 as a reference template used for distance measurement (S122). In this process, since the distance measurement and the matching error rate are not acquired during the initial setting process, the initial setting of the reference template can be performed quickly. However, when the dot pattern shifts due to factors other than the temperature of the laser light source 110, there remains a problem that the optimum reference template cannot be set for distance measurement.

FIG. 9B is a diagram showing another initial setting process for solving the problem shown in FIG. In this process, the CPU 21 acquires the current temperature (S131), measures the distance using the reference template Rt of the temperature zone Wt corresponding to the acquired current temperature (S132), and further, in this measurement, the matching error rate Ert is acquired (S133). Next, the CPU 21 determines whether or not the acquired matching error rate Ert exceeds the threshold value ES (S134). If Ert ≦ Es (S134: YES), the reference template Rt is set for distance measurement (S135). . On the other hand, if Ert ≦ Es is not satisfied (S134: NO), distance measurement is performed using reference templates respectively associated with m temperature zones before and after the temperature zone Wt (S136), and the matching error rate in each measurement is calculated. Obtain (S137). And CPU21 sets the reference template corresponding to the minimum matching error rate among the matching error rates acquired by S137 to the reference template for distance measurement (S138).

According to the processing of FIG. 9B, whether the reference template Rt corresponding to the current temperature is appropriate is determined based on the matching error rate Ert. If it is appropriate, the reference template Rt is set for distance measurement. The In this case, the initial setting of a proper reference template is performed quickly by measuring the distance once and acquiring the error rate. If the reference template Rt corresponding to the current temperature is not appropriate, an appropriate reference template is appropriately selected for distance measurement from other reference templates. Therefore, even when the dot pattern is shifted due to factors other than the temperature of the laser light source 110, an appropriate reference template can be set for distance measurement.

If any of the matching error rates acquired in S137 of FIG. 9B exceeds the threshold value Es, distance measurement and acquisition of the matching error rate are further performed using the remaining reference templates, and the matching error rate is obtained. The reference template having the smallest value may be selected.

FIG. 10 is a diagram showing processing for resetting the reference template during the actual measurement operation.

Referring to FIG. 10A, the CPU 21 acquires the current temperature based on the signal output from the temperature sensor 160 during the actual measurement operation (S201). Then, the CPU 21 compares the acquired current temperature with the temperature zone Wu corresponding to the reference template currently set for distance measurement, and determines whether the current temperature is out of the temperature zone Wu (S202). If the current temperature does not deviate from the temperature zone Wu (S202: NO), the CPU 21 returns to S201 and repeats the process. If the current temperature is out of the temperature zone Wu (S202: YES), the CPU 21 performs reference template resetting processing (S203).

Note that whether or not the reference template needs to be reset may be determined by the process of FIG. During the actual measurement operation, the CPU 21 acquires the matching error rate Er based on the distance measurement result (S211), and determines whether the acquired matching error rate Er exceeds the threshold Es (S212). If the matching error rate Er does not exceed the threshold Es (S212: NO), the CPU 21 returns to S211 and repeats the process. If the matching error rate Er exceeds the threshold Es (S212: YES), the CPU 21 performs a reference template resetting process (S213).

10A and 10B may be performed only in one of them, or both may be performed in parallel. In addition, even if the determination of S202 in FIG. 10A is YES, the processing of S203 is not performed immediately, but the processing corresponding to S211 and S212 is performed, and the matching error rate Er exceeds the threshold Es. In addition, a reference template resetting process may be performed.

In S203 and S213 of FIGS. 10A and 10B, the distance measurement is performed by the same processing as the initial setting processing shown in FIGS. 8A and 8B or FIGS. 9A and 9B. The reference template is reset. Alternatively, the reference template may be reset by the processes shown in FIGS. 11A and 11B instead of these processes.

FIG. 11 (a) is a diagram showing another resetting process applied to S203 of FIG. 10 (a).

Referring to FIG. 11A, the CPU 21 acquires the matching error rate Eru based on the result of the distance measurement performed immediately before using the reference template Ru currently in use during the actual measurement operation (S301). . Next, the CPU 21 performs distance measurement using reference templates respectively associated with n temperature zones before and after the temperature zone Wu of the reference template Ru in the reference template table RT1 (S302), and a matching error in each measurement The rate is acquired (S303). Then, the CPU 21 resets the reference template corresponding to the minimum matching error rate among the matching error rate Eru acquired in S301 and the matching error rate acquired in S303 as a reference template for distance measurement (S304). Thereafter, the CPU 21 measures the distance using the reset reference template.

FIG. 11B is a diagram showing another resetting process applied to S213 in FIG. 10B.

Referring to FIG. 11A, the CPU 21 uses reference templates respectively associated with n temperature zones before and after the temperature zone Wu of the reference template Ru currently used for distance measurement in the reference template table RT1. The distance is measured (S311), and the matching error rate in each measurement is acquired (S312). Then, the CPU 21 resets the reference template corresponding to the minimum matching error rate among the matching error rates acquired in S312 as a reference template for distance measurement (S313). Thereafter, the CPU 21 measures the distance using the reset reference template.

If any of the matching error rates acquired in S312 exceeds the threshold value Es, distance measurement and acquisition of the matching error rate are further performed using the remaining reference templates, and a reference template with the minimum matching error rate is obtained. You may make it select.

FIG. 12 is a diagram schematically showing an example of distance matching when the temperature of the laser light source 110 is changed and the emission wavelength of the laser light is changed.

FIGS. 12A and 12B show a case where distance matching is performed with the reference reference template Rb without replacing the reference template even when the temperature of the laser light source 110 changes and the emission wavelength of the laser light changes. It is a figure which shows the comparative example.

Referring to FIG. 12A, the dot pattern included in the comparison region Ct0 corresponding to the predetermined segment region RbS of the reference template Rb has a negative X-axis from the position of Ct0 ′ due to the wavelength variation of the laser beam due to the temperature change. 1 pixel in the direction and 1 pixel in the Y-axis negative direction. In this state, when the dot pattern corresponding to the segment area RbS is searched only in the X-axis direction in the search area Rt, the segment area RbS is found in the area Ct corresponding to the comparison area Ct0 ′ as shown in FIG. Even if positioned, the dots in the region Ct do not match the dots in the segment region RbS. Therefore, distance matching fails and results in an error.

On the other hand, as shown in FIG. 12C, in the case of this embodiment, the reference template for distance measurement is replaced with an appropriate reference template Rc according to the temperature change of the laser light source 110. In the matching process, the dot pattern corresponding to the segment area RcS of the replaced reference template Rc is searched in the X-axis direction in the search area Rt. In this way, as shown in FIG. 12 (d), distance matching can be appropriately performed even when the wavelength fluctuates due to a temperature change and the dot pattern shifts also in the Y-axis direction.

As described above, according to the present embodiment, the reference template used for distance acquisition is replaced with an appropriate reference template according to a temperature change, and therefore the distance is appropriately detected even if the dot pattern is shifted in the Y-axis direction. be able to.

In addition, according to the present embodiment, the reference template can be appropriately replaced by replacing the reference template at the timing when the mode hop with a variable wavelength occurs.

Further, according to the present embodiment, since the reference template is held at a temperature interval corresponding to a pixel shift amount of 1 pixel or more, the reference template is appropriately replaced while suppressing the capacity of the memory 27 and the calculation amount for the CPU 21. It can be performed.

Furthermore, in the present embodiment, the distance to the detection object is accurately measured by appropriately replacing the reference template according to the wavelength variation without controlling the wavelength to be constant by a temperature control element such as a Bertier element. be able to. Thus, the cost and size of the object detection device can be reduced.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made to the embodiment of the present invention in addition to the above. .

For example, in the above embodiment, the reference template is held at a temperature interval at which mode hops occur twice. However, the reference template may be held at a temperature interval at which mode hops occur three times or more, and FIG. As shown in the first modification, the reference template may be held at a temperature interval at which a mode hop occurs once. In this case, as shown in FIGS. 13A and 13B, reference templates Qa to Qf are set in a narrower temperature range than in the case of the present embodiment. At this time, as shown in FIG. 13C, each reference template is set such that the pixel shift amount of the dot pattern is 0.5 pixel intervals.

As a result, the number of reference templates held in the memory 27 is larger than that in the present embodiment, the capacity of the memory 27 is slightly more difficult, and the reference templates are switched at a narrow temperature interval. Although it increases, since the error rate of matching decreases, distance detection can be performed with higher accuracy.

In the above embodiment, the temperature in the vicinity of the laser light source 110 is used as a parameter for specifying the wavelength of the laser light (the extent of the dot pattern). However, the wavelength of the laser light (dot) is determined using other parameters. The extent of the pattern) may be specified. For example, as shown in Modification 2 in FIG. 14, when the imaging effective area is wider than the DP light incident area with respect to the CMOS image sensor 240, the pixel position Spn in the Y-axis direction of the upper left corner of the DP light incident area May be used as a parameter for specifying the wavelength of the laser light (the degree of spread of the dot pattern).

In this case, the reference template Rn is stored in the memory 27 in association with the pixel position Spn. Then, the pixel position in the Y-axis direction of the upper left corner of the DP light incident area is detected during actual measurement, and a reference template corresponding to the detected pixel position is read from the memory 27 and used for distance acquisition. In this case, a search segment area is set in the upper left corner of the DP light incident area, and the displacement position of this segment area is searched in the same manner as in the above embodiment. The search area at this time is an area having a predetermined width in the X-axis direction and the Y-axis direction. In this case as well, as in the case of FIG. 8, when the matching error rate exceeds the threshold value Ts, the reference template used for distance acquisition may be switched.

In the above embodiment, the laser light source 110 is a single mode semiconductor laser that oscillates in a single longitudinal mode, and the reference template is replaced at a temperature interval corresponding to the mode hop timing. You may replace a reference template at timing. For example, regardless of the mode hop timing, prepare reference templates in association with multiple reference temperatures defined at regular temperature intervals, select the most appropriate reference template from these reference templates, and acquire the distance May be used for In this case, a laser light source 110 other than a single mode semiconductor laser may be used.

In the above embodiment, the segment areas are set so that the adjacent segment areas overlap each other, but the segment areas may be set so that the segment areas adjacent to the left and right do not overlap each other. The segment areas may be set so that the segment areas adjacent in the vertical direction do not overlap each other. Further, the shift amount of the segment areas adjacent in the vertical and horizontal directions is not limited to one pixel, and the shift amount may be set to another number of pixels. Moreover, in the said embodiment, although the magnitude | size of the segment area | region was set to horizontal 15 pixels x vertical 15 pixels, it can set arbitrarily according to detection accuracy. Furthermore, in the said embodiment, although the segment area | region was set to square shape, a rectangle may be sufficient.

In the above embodiment, the segment area is set on the reference image, and the distance matching is performed by searching the position of the corresponding dot pattern on the actual measurement image. However, the segment area is set on the actual measurement image. The distance matching may be performed by searching for the position of the corresponding dot pattern on the reference image. In this case, a reference image is held for each parameter value (for example, temperature range as in the above embodiment) that can specify the wavelength of the laser beam, and the most appropriate reference image is selected from these reference images. Then, it may be used for distance acquisition.

In the above embodiment, as the error detection of distance detection, an error is determined based on whether the difference between Rsad with the highest matching rate and Rsad with the next highest matching rate exceeds a threshold. The error may be determined based on whether Rsad having the highest collation rate exceeds a predetermined threshold.

In the above embodiment, the pixel values of the pixels included in the segment area and the comparison area are binarized before calculating the matching rate between the segment area and the comparison area. Matching may be performed using the values as they are. In the above embodiment, the pixel value obtained by the CMOS image sensor 240 is binarized as it is. However, the pixel value is subjected to correction processing such as predetermined pixel weighting processing and background light removal processing. After performing, it may be binarized or multi-valued.

Further, in the above embodiment, the distance information is obtained by using the triangulation method and stored in the memory 27. However, when the main purpose is to extract the contour of the object, the distance using the triangulation method is set. The displacement amount (pixel displacement amount) of the segment area may be acquired as the distance information without calculating.

Further, in the above embodiment, the filter 230 is disposed to remove light in a wavelength band other than the wavelength band of the laser light irradiated to the target region. For example, light other than the laser light irradiated to the target region is used. In the case where a circuit configuration for removing the signal component is removed from the signal output from the CMOS image sensor 240, the filter 230 can be omitted. Further, the arrangement position of the aperture 210 may be between any two imaging lenses.

In the above embodiment, the CMOS image sensor 240 is used as the light receiving element, but a CCD image sensor can be used instead. Furthermore, the configurations of the projection optical system 100 and the light receiving optical system 200 can be changed as appropriate. The information acquisition device 1 and the information processing device 2 may be integrated, or the information acquisition device 1 and the information processing device 2 may be integrated with a television, a game machine, or a personal computer.

The embodiment of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims.

DESCRIPTION OF SYMBOLS 1 ... Information acquisition apparatus 21 ... CPU (distance acquisition part, detection part)
21b ... Distance acquisition unit (distance acquisition unit)
24 ... Temperature detection circuit (detection unit)
25 ... Imaging signal processing circuit (distance acquisition unit)
27 ... Memory (storage unit)
DESCRIPTION OF SYMBOLS 100 ... Projection optical system 110 ... Laser light source (semiconductor laser)
120 ... collimator lens 140 ... DOE (diffractive optical element)
160 ... Temperature sensor (detection unit)
200 ... Light receiving optical system 240 ... CMOS image sensor (image sensor)
S1 to Sn: Segment area (reference area)
Ra to Ru ... Reference template (reference information)
Tc: Ambient temperature (parameter)

Claims

In an information acquisition device that acquires information on a target area using light,
A projection optical system that projects laser light emitted from a laser light source onto a target area with a predetermined dot pattern;
A light receiving optical system that is arranged so as to be laterally separated by a predetermined distance with respect to the projection optical system, and that captures the target area by an image sensor;
A storage unit that holds reference information based on a reference dot pattern imaged by the light receiving optical system when the laser beam is irradiated on a reference surface;
Referring to the actual measurement information based on the actual measurement dot pattern imaged by the image sensor at the time of actual measurement and the reference information, a reference area on the standard dot pattern and an area on the actual measurement dot pattern corresponding to the reference area A distance acquisition unit that acquires distance information with respect to the reference region based on the positional relationship;
The storage unit holds a plurality of types of reference information corresponding to the extent of the dot pattern,
The distance acquisition unit selects the reference information used at the time of actual measurement from a plurality of types of the reference information stored in the storage unit, and executes the acquisition of the distance information using the selected reference information.
An information acquisition apparatus characterized by that.
The information acquisition device according to claim 1,
The laser light source is a single mode semiconductor laser that oscillates laser light in a predetermined longitudinal mode,
The storage unit holds the plurality of reference information so as to correspond to the oscillation wavelength of the laser light source that changes stepwise.
An information acquisition apparatus characterized by that.
The information acquisition device according to claim 2,
The storage unit holds the reference information so that the reference information is switched every time the oscillation wavelength of the laser light source changes by a predetermined step.
An information acquisition apparatus characterized by that.
In the information acquisition device according to any one of claims 1 to 3,
The distance acquisition unit tries the distance acquisition operation using the different reference information stored in the storage unit, and the reference information for which the distance acquisition operation was most appropriately executed in the trial is used as the distance information. Set in the reference information used for acquisition,
An information acquisition apparatus characterized by that.
In the information acquisition device according to any one of claims 1 to 3,
A detector that detects a value of a parameter that defines the extent of the dot pattern;
The storage unit holds the reference information in association with the parameter value,
The distance acquisition unit acquires the reference information corresponding to the parameter value detected by the detection unit during actual measurement from the storage unit, and sets the acquired reference information as the reference information used for acquiring the distance. To
An information acquisition apparatus characterized by that.
The information acquisition device according to claim 5,
The value of the parameter is the temperature of the laser light source,
An information acquisition apparatus characterized by that.
In the information acquisition device according to any one of claims 1 to 6,
The projection optical system includes a collimator lens on which laser light emitted from the laser light source is incident, and a diffractive optical element that converts the laser light transmitted through the collimator lens into light of a dot pattern by diffraction.
An information acquisition apparatus characterized by that.
An object detection device having the information acquisition device according to any one of claims 1 to 7.