WO2012132087A1

WO2012132087A1 - Light receiving device, information acquiring device, and object detecting device having information acquiring device

Info

Publication number: WO2012132087A1
Application number: PCT/JP2011/075389
Authority: WO
Inventors: 楳田　勝美
Original assignee: 三洋電機株式会社
Priority date: 2011-03-25
Filing date: 2011-11-04
Publication date: 2012-10-04
Also published as: JP2014112033A

Abstract

Provided are a light receiving device, which can narrow, to a narrow band, the wavelength band of light to be inputted to a light detector, thereby improving accuracy of distance detection, an object detecting device, and an information acquiring device. A light receiving optical system (12) of an information acquiring device (1) has: a bandpass filter (121a), which removes light in a first wavelength band other than the wavelength band of laser light, from light to be collected to a CMOS image sensor (124) through an image pickup lens (122); and a bandpass filter (121b), which removes light in a second wavelength band other than the wavelength band of the laser light. The bandpass filter (121b) limits, with the bandpass filter (121a), the wavelength band of the light to be collected to the CMOS image sensor (124) within a range that includes the wavelength band of the laser light.

Description

[Name of invention determined by ISA based on Rule 37.2] Light receiving device, information acquisition device, and object detection device having information acquisition device

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

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 (imaged) by a photodetector such as a CMOS image sensor. The Various types of distance image sensors are known.

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

In the object detection apparatus, light from the target area is collected by the imaging lens and guided to the photodetector. In this case, the collected light includes not only laser light having a dot pattern but also light unnecessary for distance detection such as sunlight and light from room lights. Sunlight or light from room lights has a higher intensity than laser light having a dot pattern taken in from the target area. Therefore, when such unnecessary light enters the photodetector, the accuracy of distance detection is greatly degraded. For this reason, it is necessary to remove these unnecessary lights appropriately.

A band pass filter can be used to remove unwanted light. In this case, the band-pass filter is configured in a narrow band so that the influence of unnecessary light can be suppressed. Furthermore, when the bandpass filter is arranged in front of the imaging lens, the bandpass filter needs to be able to limit the passband in the entire range of light capturing angles of the imaging lens. However, since the band-pass filter has an angle dependency, it is difficult to narrow the pass wavelength band to a narrow band in the entire range of the capturing angle of the imaging lens with one band-pass filter.

The present invention has been made to solve such a problem, and the wavelength band of light incident on the photodetector can be narrowed to a narrow band, thereby improving the accuracy of distance detection. An object of the present invention is to provide a light receiving device, an object detection device, and an information acquisition device.

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 device according to this aspect is arranged so as to be lined up with a projection optical system that projects a laser beam with a predetermined dot pattern on a target area and spaced apart by a predetermined distance from the projection optical system, A light receiving optical system for imaging a target area. The light receiving optical system includes a photodetector for imaging the target area, an imaging lens for condensing light from the target area on the photodetector, and a light collecting system for the photodetector via the imaging lens. A first wavelength limiting unit that removes light in a first wavelength band other than the wavelength band of the laser light, and light collected on the photodetector via the imaging lens. Among them, by removing light in the second wavelength band other than the wavelength band of the laser light, in combination with the first wavelength limiting unit, the wavelength band of the light condensed on the photodetector is changed. And a second wavelength limiting unit that limits the laser beam to a range including the wavelength band.

The second aspect of the present invention relates to a light receiving device. The light-receiving device according to this aspect includes the light-receiving optical system according to the first aspect.

The third 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 a light receiving device, an object detection device, and an information acquisition device capable of narrowing the wavelength band of light incident on a photodetector to a narrow band, thereby improving the accuracy of distance detection. can do.

The characteristics of the present invention will be further clarified by the description of the embodiments shown below. However, the following embodiment is merely one embodiment of the present invention, and the meaning of the term of the present invention or each constituent element is not limited to that described in the following embodiment. Absent.

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 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 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 structure of the projection optical system which concerns on embodiment, and a light-receiving optical system. It is a figure which shows the structure of embodiment, the light reception optical system of the modification example 1 and the modification example 2. It is a figure which shows the pass wavelength band characteristic which concerns on embodiment. It is a figure which shows the pass wavelength band characteristic which concerns on the example 1 of a change. It is a figure which shows the pass wavelength band characteristic which concerns on the example 2 of a change. It is a figure which shows the structure of the light-receiving optical system of the other modification.

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. Note that a device including the information acquisition device 1 and the information processing device 2 corresponds to the object detection device of the present invention.

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 sends a control signal to the television 3 according to the gesture. An application program to output 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 11 and a light receiving optical system 12 as a configuration of the optical unit. In addition, the information acquisition device 1 includes a CPU (Central Processing Unit) 21, a laser driving circuit 22, an imaging signal processing circuit 23, an input / output circuit 24, and a memory 25 as a circuit unit.

The projection optical system 11 irradiates a target area with laser light having a predetermined dot pattern. The light receiving optical system 12 receives the laser beam reflected from the target area. The configurations of the projection optical system 11 and the light receiving optical system 12 will be described later with reference to FIG.

The CPU 21 controls each unit according to a control program stored in the memory 25. With this control program, the CPU 21 has functions of a laser control unit 21 a for controlling a laser light source 111 (described later) in the projection optical system 11 and a three-dimensional distance calculation unit 21 b for generating three-dimensional distance information. Is granted.

The laser drive circuit 22 drives a laser light source 111 (described later) according to a control signal from the CPU 21. The imaging signal processing circuit 23 controls a CMOS image sensor 124 (described later) in the light receiving optical system 12 and sequentially captures the signal (charge) of each pixel generated by the CMOS image sensor 124 for each line. Then, the captured signals are sequentially output to the CPU 21.

CPU21 calculates the distance from the information acquisition apparatus 1 to each part of a detection target based on the signal (imaging signal) supplied from the imaging signal processing circuit 23 by the process by the three-dimensional distance calculation part 21b. The input / output circuit 24 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. 3A is a diagram schematically showing the irradiation state of the laser light on the target region, and FIG. 3B is a diagram schematically showing the light receiving state of the laser light in the CMOS image sensor 124. For the sake of convenience, FIG. 6B shows a light receiving state when a flat surface (screen) exists in the target area.

As shown in FIG. 5A, the projection optical system 11 emits laser light having a dot pattern (hereinafter, the entire laser light having this pattern is referred to as “DP light”) toward the target region. Is done. In FIG. 4A, the DP light projection area is indicated by a solid frame. In the light beam of DP light, dot regions (hereinafter simply referred to as “dots”) in which the intensity of the laser light is increased by the diffractive action by the diffractive optical element are scattered according to the dot pattern by the diffractive action by the diffractive optical element. Yes.

In FIG. 3A, for convenience, the light beam of DP light is divided into a plurality of segment regions arranged in a matrix. In each segment area, dots are scattered in a unique pattern. The dot dot pattern in one segment area is different from the dot dot pattern in all other segment areas. As a result, each segment area can be distinguished from all other segment areas with a dot dot pattern.

If there is a flat surface (screen) in the target area, the segment areas of DP light reflected thereby are distributed in a matrix on the CMOS image sensor 124 as shown in FIG. For example, the light in the segment area S0 on the target area shown in FIG. 5A enters the segment area Sp shown in FIG. In FIG. 3B as well, the light flux region of DP light is indicated by a solid frame, and for convenience, the light beam of DP light is divided into a plurality of segment regions arranged in a matrix.

In the three-dimensional distance calculation unit 21b, it is detected which position on the CMOS image sensor 124 each segment area is incident on, and each part (each segment area) of the detection target object is detected from the light receiving position based on the triangulation method. To the irradiation position) is detected. Details of such a detection technique 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).

FIG. 4 is a perspective view showing an installation state of the projection optical system 11 and the light receiving optical system 12.

The projection optical system 11 and the light receiving optical system 12 are installed on a base plate 300 having high thermal conductivity. The optical members constituting the projection optical system 11 are installed on the chassis 11 a, and the chassis 11 a is installed on the base plate 300. Thereby, the projection optical system 11 is installed on the base plate 300.

The light receiving optical system 12 is installed on the upper surface of the two pedestals 300a on the base plate 300 and the upper surface of the base plate 300 between the two pedestals 300a. A CMOS image sensor 124, which will be described later, is installed on the upper surface of the base plate 300 between the two pedestals 300a, and a holding plate 12a is installed on the upper surface of the pedestal 300a. A lens holder 12b for holding 122 is installed.

The projection optical system 11 and the light receiving optical system 12 are installed side by side with a predetermined distance in the X axis direction so that the projection center of the projection optical system 11 and the imaging center of the light receiving optical system 12 are aligned on a straight line parallel to the X axis. Has been. On the back surface of the base plate 300, a circuit board that holds the circuit unit (see FIG. 2) of the information acquisition device 1 is installed.

A hole 300 b for taking out the wiring of the laser light source 111 to the back of the base plate 300 is formed in the lower center of the base plate 300. In addition, an opening 300 c for exposing the connector 12 c of the CMOS image sensor 124 to the back of the base plate 300 is formed below the installation position of the light receiving optical system 12 on the base plate 300.

In addition, the left half of FIG. 4 constitutes a light emitting device, and the right half constitutes a light receiving device. The right half light receiving device corresponds to the light receiving device of the present invention.

FIG. 5 is a diagram schematically showing the configuration of the projection optical system 11 and the light receiving optical system 12 according to the present embodiment.

The projection optical system 11 includes a laser light source 111, a collimator lens 112, a rising mirror 113, and a diffractive optical element (DOE: Diffractive Optical Element) 114. The light receiving optical system 12 includes a filter 121, an imaging lens 122, an aperture 123, and a CMOS image sensor 124.

The laser light source 111 outputs laser light in a narrow wavelength band with a wavelength of about 830 nm. The laser light source 111 is installed so that the optical axis of the laser light is parallel to the X axis. The collimator lens 112 converts the laser light emitted from the laser light source 111 into substantially parallel light. The collimator lens 112 is installed so that its own optical axis is aligned with the optical axis of the laser light emitted from the laser light source 111. The raising mirror 113 reflects the laser beam incident from the collimator lens 112 side. The optical axis of the laser beam is bent 90 ° by the rising mirror 113 and becomes parallel to the Z axis.

The DOE 114 has a diffraction pattern on the incident surface. The diffraction pattern is composed of, for example, a step type hologram. Due to the diffractive action of this diffraction pattern, the laser light reflected by the rising mirror 113 and incident on the DOE 114 is converted into a laser light having a dot pattern and irradiated onto the target area. The diffraction pattern is designed to be a predetermined dot pattern in the target area.

The laser light reflected from the target area passes through the filter 121 and enters the imaging lens 122.

The filter 121 transmits light in a wavelength band including the emission wavelength (about 830 nm) of the laser light source 111 and cuts other wavelength bands. The filter 121 is configured by combining two optical interference type band-

pass filters

121a and 121b. Each of the

bandpass filters

121a and 121b is configured by laminating a plurality of dielectric films on a transparent substrate. The characteristics of the

bandpass filters

121a and 121b will be described later with reference to FIG.

The imaging lens 122 condenses the light incident through the filter 121 on the CMOS image sensor 124. The imaging lens 122 includes three

lenses

122a, 122b, and 122c. The three

lenses

122a, 122b, 122c are made of a plastic material. An aperture 123 is interposed between the uppermost lens 122a and the middle lens 122b.

The aperture 123 has an opening in the center according to the capture angle of the imaging lens 122. That is, the opening of the aperture 123 has a diameter corresponding to the F number of the uppermost lens 122 a of the imaging lens 122.

The CMOS image sensor 124 receives the light collected by the imaging lens 122 and outputs a signal (charge) corresponding to the amount of received light to the imaging signal processing circuit 23 for each pixel. Here, in the CMOS image sensor 124, 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 23 with high response from light reception in each pixel.

The filter 121 is disposed so that the light receiving surface is orthogonal to the Z axis. The imaging lens 122 is installed so that the optical axis is parallel to the Z axis. The CMOS image sensor 124 is installed such that the light receiving surface is perpendicular to the Z axis. The filter 121, the imaging lens 122, and the CMOS image sensor 124 are arranged so that the center of the filter 121 and the center of the light receiving region of the CMOS image sensor 124 are aligned on the optical axis of the imaging lens 122.

The projection optical system 11 and the light receiving optical system 12 are installed on the base plate 300 as described with reference to FIG. A circuit board 200 is further installed on the lower surface of the base plate 300, and wirings (flexible boards) 201 and 202 are connected from the circuit board 200 to the laser light source 111 and the CMOS image sensor 124. On the circuit board 200, the circuit unit of the information acquisition apparatus 1 such as the CPU 21 and the laser driving circuit 22 shown in FIG.

FIG. 6A is a cross-sectional view showing a more detailed configuration of the light receiving device. FIG. 6A is a cross-sectional view taken along the line A-A ′ of FIG. However, in FIG. 6A, the lens holder 12b of FIG. 4 is omitted, and the CMOS image sensor 124 only shows the cover glass 124a.

The light receiving device includes a filter holder 125, a lens barrel 126, and a spacer 127 in addition to the

bandpass filters

121a and 121b, lenses 122a to 122c, the aperture 123, and the CMOS image sensor 124 shown in FIG. ing.

The filter holder 125 has a two-stage circular recess formed coaxially, and

bandpass filters

121a and 121b are mounted in the recesses, respectively. The lens barrel 126 has a two-stage circular recess formed coaxially, the lenses 122a to 122c and the aperture 123 are accommodated in the lower recess, and the filter holder 125 is mounted in the upper recess. A lens 122c, a spacer 127, a lens 122b, an aperture 123, and a lens 122a are stacked in order from the bottom in the concave portion on the lower side of the lens barrel 126. Further, the filter holder 125 is mounted on the upper surface of the lens 122a. 126 is attached. The optical axes of the lenses 122a to 122c coincide with each other, and the optical axes pass through the centers of the

bandpass filters

121a and 121b and the center of the light receiving region of the CMOS image sensor 124. The lens barrel 126 is attached to the lens holder 12b of FIG.

In this embodiment, light is taken in the range of the taking angle defined by the aperture 123 around the optical axes of the lenses 122a to 122c, and guided to the cover glass 124a of the CMOS image sensor 124. A solid line shown on the lower surface side of the cover glass 124a is an imaging plane Pa formed by the lenses 122a to 122c, and a light receiving surface of the CMOS image sensor 124 is arranged on the imaging plane Pa.

In the present embodiment, the maximum value of the incident angle of the light ray in the range of the capturing angle with respect to the incident surface of the bandpass filter 121a is 35 °. Further, the maximum value of the incident angle of the light beam traveling from the lens 122c toward the cover glass 124a with respect to the incident surface of the cover glass 124a is 37 °.

7A is a diagram showing the light transmission characteristics of the bandpass filter 121a, and FIG. 7B is a diagram showing the light transmission characteristics of the bandpass filter 121b. 7A and 7B, the horizontal axis represents wavelength and the vertical axis represents transmittance. 7A and 7B show the light transmission characteristics when the incident angle is 0 ° (solid line) and when the incident angle is 35 ° (broken line). The incident angle of 35 ° is the maximum value of the incident angle with respect to the incident surface of the bandpass filter 121a of the light ray in the range of the capturing angle as described above.

In this embodiment, unnecessary light is removed according to the characteristics of FIGS. 7A and 7B by the two band-

pass filters

121a and 121b. For this reason, unnecessary light is removed from the light within the capture angle range by the optical characteristics of FIG. 7C, which is a combination of the characteristics of FIGS. 7A and 7B. In FIG. 7C, a range Wa is a pass wavelength bandwidth when the transmittance of the two

band pass filters

121a and 121b is 85% or more in the range of incident angles of 0 ° to 35 °. In this case, the pass wavelength band is about 810 to 850 nm, and the bandwidth Wa is about 40 nm. Note that the bandwidth Wa ′ of the bandpass filter at 0 ° is about 90 nm.

Thus, according to the present embodiment, by combining the two

band pass filters

121a and 121b, narrow band filter characteristics can be realized in the range of incident angles of 0 ° to 35 °. Therefore, according to the present embodiment, it is possible to narrow the pass wavelength band to a narrow band in the entire range of the capturing angle of the imaging lens 122, thereby improving the accuracy of object detection. Note that relatively inexpensive band pass filters can be used for the two

band pass filters

121a and 121b.

<Modification 1>
FIG. 6B is a cross-sectional view illustrating the configuration of the light receiving device according to the first modification. This figure is a cross-sectional view of the light receiving device of this modification example, cut in the same manner as in FIG. In FIG. 6B, the same parts as those in FIG. 6A are denoted by the same reference numerals. Also in FIG. 6B, as in FIG. 6A, the lens holder 12b of FIG. 4 is omitted, and the CMOS image sensor 124 only shows the cover glass 124a.

As shown in the figure, in this modification example, only one bandpass filter 121c is used, and the shape of the filter holder 125a is changed accordingly. Of the three lenses constituting the imaging lens 122, the uppermost lens 122d is changed from the above embodiment.

The filter holder 125a has one circular recess, and the bandpass filter 121c is attached to this recess. The lens 122d is made of a material that absorbs visible light. For example, the lens 122d is formed of a material obtained by mixing a plastic material with a dye mainly composed of methacrylic resin. As long as it is a dye that absorbs visible light, another dye may be mixed into the lens 122d. The lens action of the lens 122d is the same as that of the lens 122a in FIG.

8A is a diagram showing the light transmission characteristics of the lens 122d, and FIG. 8B is a diagram showing the light transmission characteristics of the bandpass filter 121c. 8A and 8B, the horizontal axis represents wavelength and the vertical axis represents transmittance. 8A and 8B show the light transmission characteristics when the incident angle is 0 ° (solid line) and when it is 35 ° (broken line). Note that the incident angle of 35 ° is the maximum value of the incident angle of the light beam in the range of the capturing angle of the imaging lens 122 with respect to the incident surface of the bandpass filter 121c, as in the case of the above embodiment.

As shown in FIG. 8A, the light transmission characteristics of the lens 122d are substantially the same when the incident angles are 0 ° and 35 °, and the light transmission characteristics of the lens 122d have almost no angle dependency.

In this modification, unnecessary light is removed by the bandpass filter 121c and the lens 122d in accordance with the characteristics shown in FIGS. 8A and 8B, respectively. Therefore, unnecessary light is removed from the light within the capture angle range by the optical characteristics of FIG. 8C, which is a combination of the characteristics of FIGS. 8A and 8B. In FIG. 8C, a range Wb is a pass wavelength bandwidth when the transmittance of the bandpass filter 121c and the lens 122d is 85% or more in the range of incident angles of 0 ° to 35 °. Also in this case, the pass wavelength band is about 810 to 850 nm, and the bandwidth Wb is about 40 nm. Note that the bandwidth Wb ′ of the bandpass filter at 0 ° is about 90 nm.

Thus, according to this modified example, by combining the band-pass filter 121c and the lens 122d, it is possible to realize a narrow-band filter characteristic in an incident angle range of 0 ° to 35 °. Therefore, according to the present embodiment, it is possible to narrow the pass wavelength band to a narrow band in the entire range of the capturing angle of the imaging lens 122, thereby improving the accuracy of object detection. Note that a relatively inexpensive bandpass filter can be used as the bandpass filter 121c. Further, even if a dye is mixed in the lens 122d, the cost of the lens 122d does not increase so much.

Furthermore, according to this modification, one bandpass filter can be omitted as compared with the above embodiment. Therefore, the number of parts can be suppressed, and the size of the light receiving device in the optical axis direction of the imaging lens 122 can be reduced. That is, in FIG. 6A, the height from the imaging plane Pa to the upper end of the filter holder 125 is Ha, but in this modified example, the height from the imaging plane Pb to the upper end of the filter holder 125 is increased. It can be suppressed to Hb.

In the present modification, a dye for absorbing visible light is mixed into the uppermost lens 122d. However, instead of the uppermost lens 122d, the middle lens 122b or the lowermost lens 122c absorbs visible light. You may mix dye for. Alternatively, any two or all of the three

lenses

122d, 122b, and 122c may be mixed with a dye for absorbing visible light.

<Modification 2>
FIG. 6C is a cross-sectional view illustrating a configuration of the light receiving device according to the second modification. This figure is a cross-sectional view of the light receiving device of this modification example, cut in the same manner as in FIG. In FIG. 6C, the same parts as those in FIG. Also in FIG. 6C, as in FIG. 6A, the lens holder 12b of FIG. 4 is omitted, and the CMOS image sensor 124 only shows the cover glass 124a.

As shown in the figure, in this modification, the imaging lens 122 of FIG. 6A is configured by four lenses 122e to 122h, and the shape of the lens barrel 126a is changed from that of the lens barrel 126 of FIG. . Further, the filter holder 125 of FIG. 6A is omitted, and one band pass filter 121d is disposed between the lens 122h and the cover glass 124a.

The lens barrel 126a has a cylindrical shape with an open lower surface, and a circular hole 126b serving as an aperture is formed at the center of the upper surface. The upper surface of the hole 126b is chamfered. The hole 126b defines the light capture angle of the lens 122e.

Lenses

122e, 122f, 122g, and 122h are accommodated in order from the top in the circular recess in the lens barrel 126a, and

spacers

127a and 127b are provided between the

lenses

122e and 122f and between the

lenses

122f and 122g, respectively. It is inserted.

The optical axes of the lenses 122e to 122h coincide with each other, and this optical axis passes through the center of the hole 126b, the center of the bandpass filter 121d, and the center of the light receiving region of the CMOS image sensor 124. The lens barrel 126a is attached to the lens holder 12b of FIG.

In this modification, light is taken in the range of the taking angle defined by the hole 126b around the optical axes of the lenses 122e to 122h, and guided to the cover glass 124a of the CMOS image sensor 124. The solid line shown on the lower surface side of the cover glass 124a is the image plane Pc formed by the lenses 122e to 122h.

In this modified example, the maximum value of the incident angle of the light beam in the range of the capturing angle with respect to the incident surface of the lens 122e is 35 ° as in the above embodiment. The maximum value of the incident angle of the light beam traveling from the lens 122h toward the cover glass 124a to the incident surface of the cover glass 124a is 20 °, which is smaller than that in the above embodiment.

In this modification, the imaging lens 122 is configured by combining the four lenses 122e to 122h in order to reduce the maximum incident angle of the light beam to the cover glass 124a. In this modified example, the imaging plane Pc is wider than the imaging plane Pa (see FIG. 6A) in the above embodiment. In this modified example, a CMOS image sensor 124 different from the above embodiment is used in accordance with a change in the incident angle and the width of the imaging surface.

In this modified example, the uppermost lens 122e is a material in which a dye for absorbing visible light is mixed into a plastic material, as in modified example 1 above. Further, the band pass filter 121d has a light transmission characteristic in which the transmittance is good when the incident angle is in the range of 0 to 20 °.

9A is a diagram illustrating the light transmission characteristics of the lens 122e, and FIG. 9B is a diagram illustrating the light transmission characteristics of the bandpass filter 121d. 9A and 9B, the horizontal axis represents wavelength and the vertical axis represents transmittance.

FIG. 9A shows the light transmission characteristics when the incident angle of the light beam with respect to the lens 122e is 0 ° (solid line) and 35 ° (dashed line). Here, the incident angle 35 ° is the maximum value of the incident angle with respect to the incident surface of the lens 122e of the light ray in the range of the capturing angle of the imaging lens 122, as in the case of the above embodiment. FIG. 9B shows light transmission characteristics when the incident angle with respect to the band-pass filter 121d is 0 ° (solid line) and 20 ° (broken line). Here, the incident angle of 20 ° is the maximum value of the incident angle of the light ray incident on the bandpass filter 121d.

As shown in FIG. 9A, as in the first modification, the light transmission characteristic of the lens 122e hardly shows any angle dependency.

In this modified example, unnecessary light is removed by the lens 122e and the band-pass filter 121d according to the characteristics of FIGS. 9A and 9B, respectively. For this reason, unnecessary light is removed from the light within the capture angle range by the optical characteristics of FIG. 9C, which is a combination of the characteristics of FIGS. 9A and 9B. In FIG. 9C, a range Wc is a pass wavelength bandwidth when the transmittance of the lens 122e and the band pass filter 121d is 85% or more in the range of the incident angle with respect to the pass filter 121d of 0 ° to 20 °. It is. In this case, the pass wavelength band is about 810 to 850 nm, and the bandwidth Wc is about 40 nm. Note that the bandwidth Wc ′ of the bandpass filter at 0 ° is about 50 nm.

As described above, according to this modified example, by combining the lens 122e and the band-pass filter 121d, a narrow band filter characteristic can be realized in an incident angle range of 0 ° to 20 ° with respect to the band-pass filter 121d. Can do. Therefore, according to the present embodiment, it is possible to narrow the pass wavelength band to a narrow band in the entire range of the capturing angle of the imaging lens 122, thereby improving the accuracy of object detection. Note that a relatively inexpensive bandpass filter can be used as the bandpass filter 121e. Further, even if a dye is mixed in the lens 122e, the cost of the lens 122e does not increase so much.

Furthermore, according to this modification, one bandpass filter can be omitted as compared with the above embodiment. Therefore, the number of parts can be suppressed, and the size of the light receiving device in the optical axis direction of the imaging lens 122 can be reduced. That is, in FIG. 6A, the height from the imaging plane Pa to the upper end of the filter holder 125 is Ha, but in this modification, the height from the imaging plane Pc to the upper end of the filter holder 125 is increased. It can be suppressed to Hc.

In addition, according to this modified example, since the maximum incident angle of the light beam incident on the bandpass filter 121d is suppressed to 20 °, as shown in FIG. 9B, the wavelength of the bandpass filter 121d is around 830 nm. Can be narrowed. As a result, as shown in FIG. 9C, the bandwidth Wc ′ when the lens 122e and the bandpass filter 121d are combined is changed to the bandwidths Wa ′ and Wb of FIG. 7C and FIG. It can be significantly narrower than 'and can further enhance the effect of removing unnecessary light. That is, the range of the difference between the bandwidth Wc ′ and the bandwidth Wc of the pass wavelength band is a range of wavelengths that are originally desired to be removed, and the wider the range of this difference, the unnecessary light having the wavelengths that are originally desired to be removed. Passes through the lens 122e and the band-pass filter 121d. In the present modification, the bandwidth Wc ′ is significantly narrower than the bandwidths Wa ′ and Wb ′ in FIGS. 7C and 8C, so that such unnecessary light can be effectively removed. it can. The bandwidth Wc of the pass wavelength band only needs to be wide enough to cope with the wavelength variation of the laser light due to the temperature change of the laser light source 111 or the like. According to this modified example, the bandwidth Wc of the pass wavelength band can be narrowed down to an area that can accommodate the wavelength variation of the laser light.

In this modified example, a dye for absorbing visible light is mixed into the uppermost lens 122e. However, a dye for absorbing visible light is added to any of the lenses 122f to 122h instead of the uppermost lens 122e. May be mixed. Alternatively, any two, three, or all of the four lenses 122e to 122h may be mixed with a dye for absorbing visible light.

<Other changes>
FIGS. 10A and 10B are cross-sectional views showing configurations in which the light-receiving device according to Modification 1 shown in FIG. 6B is further changed. 10 (a) and 10 (b), the same parts as those in FIG. 6 (b) are denoted by the same reference numerals.

In the modified example of FIG. 10A, the uppermost lens is returned to the same lens 122a as in the above embodiment, compared to the modified example 1 of FIG. 6B, and between the lens 122c and the cover glass 124a. The light absorbing plate 128 is disposed so as to be perpendicular to the optical axes of the lenses 122a to 122c.

The light absorbing plate 128 has a flat plate shape with a constant thickness, and is formed from a material in which a dye for absorbing visible light is mixed into a plastic material. The light absorbing plate 128 has, for example, the same light transmission characteristics as in FIG. By configuring the light absorbing plate 128 in this way, the band-pass filter 121c and the light absorbing plate 128 can be combined to realize the same filter characteristics as in FIG. 8C, and the accuracy of object detection can be increased. .

In addition, the maximum value of the incident angle of the light beam incident on the light absorbing plate 128 is 37 ° as described above, and is larger than 35 ° which is the maximum value of the incident angle in the bandpass filter 121c. However, since the light absorption plate 128 has no angle dependency, visible light can be appropriately removed even if the light absorption plate 128 is arranged at a position where the maximum value of the incident angle of light rays is large. .

Further, in the modified example of FIG. 10A, the light absorbing plate 128 is separately arranged. Instead of arranging the light absorbing plate 128, for example, a dye for absorbing visible light is applied to the cover glass 124a. May be mixed. Further, the arrangement position of the light absorbing plate 128 may be changed to another position such as the upper surface of the bandpass filter 121c or between the bandpass filter 121c and the lens 122a. The light absorbing plate 128 may be integrated with the bandpass filter 121c by being attached to the upper surface or the lower surface.

Next, in the modified example of FIG. 10B, compared with the modified example 1 of FIG. 6B, the uppermost lens is returned to the lens 122a similar to that of the above embodiment, and the bandpass filter 121c is bandpassed. The filter 121e is replaced.

10B is an enlarged view of the layer structure of the bandpass filter 121e on the right side of FIG. As illustrated, the bandpass filter 121e has a structure in which a dielectric layer 121e2 in which a plurality of dielectric films are stacked on a substrate 121e1 is formed. The substrate 121e1 has a flat plate shape with a constant thickness, and is formed from a material in which a dye for absorbing visible light is mixed into a plastic material. As the dye, a dye mainly composed of a methacrylic resin can be used as in the above embodiment. As described above, the configuration of the bandpass filter 121e is the same as the configuration of the bandpass filter 121c according to the first modification except that the dye is mixed in the substrate 121e1.

In this modified example, the substrate 121e1 has, for example, the same light transmission characteristics as in FIG. In addition, the dielectric layer 121e2 has, for example, light transmission characteristics similar to those in FIG. By configuring the substrate 121e1 and the dielectric layer 121e2 in this way, the substrate 121e1 and the dielectric layer 121e2 can be combined to realize the same filter characteristics as in FIG. 8C, and the accuracy of object detection can be improved. it can.

In addition, according to this modified example, since the dye for absorbing visible light is mixed into the substrate 121e1, compared to the case where the light absorbing plate 128 is separately disposed as in the modified example of FIG. The number of parts can be reduced, and the size in the lens optical axis direction can be reduced.

FIG. 10C is a cross-sectional view showing a configuration in which the light receiving device according to the modification example 2 shown in FIG. 6C is further changed. In FIG. 10C, the same parts as those in FIG.

In this modified example, compared with the modified example 2 in FIG. 6C, the uppermost lens is returned to the lens 122a similar to the above embodiment, and the bandpass filter 121d is replaced with the bandpass filter 121f.

The layer structure of the bandpass filter 121f is shown enlarged on the right side of FIG. As illustrated, the band-pass filter 121f has a structure in which a dielectric layer 121f2 in which a plurality of dielectric films are stacked is formed on a substrate 121f1. The substrate 121f1 has a flat plate shape with a constant thickness, and is formed of a material obtained by mixing a plastic material with a dye for absorbing visible light. As described above, except that the dye is mixed in the substrate 121f1, the configuration of the bandpass filter 121f is the same as the configuration of the bandpass filter 121d of FIG.

In this modified example, the substrate 121f1 has, for example, the same light transmission characteristics as in FIG. In addition, the dielectric layer 121f2 has, for example, light transmission characteristics similar to those in FIG. By configuring the substrate 121f1 and the dielectric layer 121f2 in this way, the substrate 121f1 and the dielectric layer 121f2 can be combined to realize the same filter characteristics as in FIG. 9C, and the accuracy of object detection can be improved. it can.

The embodiment and the modification of the present invention have been described above. However, the present invention is not limited to the above-described embodiment and the modification, and the embodiment of the present invention is various in addition to the above. Can be changed.

For example, in the above modified example, the dye mixed into the lens or the light absorbing plate is supposed to absorb visible light, but a light absorbing material that absorbs light in other wavelength bands is mixed into the lens or the light absorbing plate. You may make it. That is, it is only necessary to realize a narrow pass wavelength band including the wavelength band of the laser light by combining the transmission wavelength characteristics of the mixed light absorbing material and the transmission wavelength characteristics of the band pass filter.

In the above-described embodiment and modification, the CMOS image sensor 124 is used as the photodetector, but a CCD image sensor can be used instead.

In the above-described embodiment and modification, the laser light source 111 and the collimator lens 112 are arranged in the X-axis direction, and the optical axis of the laser light is bent in the Z-axis direction by the rising mirror 113. The laser light source 111 may be arranged so as to emit in the axial direction, and the laser light source 111, the collimator lens 112, and the DOE 114 may be arranged side by side in the Z-axis direction. In this case, the rising mirror 113 can be omitted, but the dimension of the projection optical system 11 increases in the Z-axis direction.

Further, as described above, the embodiment and various modified examples have been described, but these can be implemented in combination as appropriate.

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 2 Information processing apparatus 11 Projection optical system 12 Light reception optical system 111 Laser light source 122 Imaging lens 122a-122h Lens (lens element)
124 CMOS image sensor (photodetector)
121a, 121b Band pass filters (first wavelength limiting unit, second wavelength limiting unit)
121c, 121d Band pass filters (first wavelength limiting unit)
122d, 122e Lens (second wavelength limiting unit)
121e1, 121f1 substrate (substrate, light absorbing plate)
121e2, 121f2 Dielectric layer (dielectric film)
128 light absorber

Claims

In an information acquisition device that acquires information on a target area using light,
A projection optical system that projects a laser beam with a predetermined dot pattern onto a target area;
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, and
The light receiving optical system is;
A photodetector for imaging the target area;
An imaging lens for condensing light from the target area onto the photodetector;
A first wavelength limiting unit that removes light in a first wavelength band other than the wavelength band of the laser light out of the light condensed on the photodetector through the imaging lens;
By removing light in a second wavelength band other than the wavelength band of the laser light from the light focused on the photodetector via the imaging lens, the first wavelength limiting unit is combined. Then, a second wavelength limiting unit that limits a wavelength band of the light condensed on the photodetector to a range including the wavelength band of the laser light,
An information acquisition apparatus characterized by that.
The information acquisition device according to claim 1,
Each of the first wavelength limiting unit and the second wavelength limiting unit is an optical interference type bandpass filter having different pass wavelength characteristics.
An information acquisition apparatus characterized by that.
The information acquisition device according to claim 1,
The first wavelength limiting unit is an optical interference bandpass filter,
The second wavelength limiting unit is the imaging lens containing a light absorbing material that absorbs light in a predetermined wavelength band.
An information acquisition apparatus characterized by that.
In the information acquisition device according to claim 3,
The imaging lens includes a plurality of lens elements, and one of these lens elements contains the light absorbing material,
An information acquisition apparatus characterized by that.
The information acquisition device according to claim 1,
The first wavelength limiting unit is an optical interference bandpass filter,
The second wavelength limiting unit is a flat light absorbing plate containing a light absorbing material that absorbs light in a predetermined wavelength band.
An information acquisition apparatus characterized by that.
The information acquisition device according to claim 4,
The bandpass filter includes a flat substrate and a dielectric multilayer film laminated on the substrate, and the light absorption plate absorbs light in a predetermined wavelength band on the substrate of the bandpass filter. It contains an absorbent material.
An information acquisition apparatus characterized by that.
In the information acquisition device according to any one of claims 3 to 6,
The imaging lens is configured such that a light spreading angle toward the photodetector is smaller than a light capturing angle of the imaging lens,
The bandpass filter is disposed between the imaging lens and the photodetector.
An information acquisition apparatus characterized by that.
A light receiving device comprising the light receiving optical system according to any one of claims 1 to 7.
An object detection device having the information acquisition device according to any one of claims 1 to 7.