• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A distance measuring device (1) is configured to measure a distance to an object (K). The distance measuring device (1) includes a light source (11) configured to emit a projection beam (L1) on the object (K), and a light receiving element (18) configured to return the projection beam (L1) from the projection beam Object (K) is reflected to detect. The light source (11) is a laser light source configured to emit pulsed light in an ultraviolet range to a blue color range as the projection beam (L1), and the light receiving element (18) is an avalanche photodiode exhibiting spectral sensitivity in an ultraviolet. Range to a blue color range and works in a Geiger mode.
    公开号:CH713186B1
    申请号:CH00417/18
    申请日:2016-06-21
    公开日:2018-09-14
    发明作者:Mase C/O Hamamatsu Photonics K K Mitsuhito；Iwashina C/O Hamamatsu Photonics K K Shinya；Suzuki C/O Hamamatsu Photonics K K Takashi
    申请人:Hamamatsu Photonics Kk；
    IPC主号:
    专利说明:

    description
    Technical Field The present invention relates to a distance measuring device.
    Background Currently, the development of a distance measuring device that uses a time of flight (TOF) scheme in which light such as laser light is projected onto an object, return light from the object is then detected, and a distance to the object is proceeding is measured based on the time from when light is projected onto the object until when return light is detected. It is believed that such a distance measuring device would be mounted, for example, as an automatic driving support system in a vehicle such as an automobile. In an automatic driving support system, a distance between a vehicle driving and an object (including a human body) is measured by the distance measuring device. The collision between the vehicle and the object can be expected to be avoided when controlling a vehicle speed based on the measurement result.
    [0003] As a distance measuring device in the prior art, there is, for example, a radar device described in Patent Literature 1. The radar device includes a light source, a diode, and a light detection control unit. A single photon avalanche diode (SPAD, single photon avalanche diode) is used as a diode configured to detect return light from an object. The light detection unit operates the SPAD after a point in time at which scattered light inside the device enters the SPAD due to light emitted from the light source, and thus eliminates the influence of the scattered light.
    quotes list
    Patent Literature Patent Literature 1: Japanese Unexamined Patent Publication No. 2015-117970
    Summary of the invention
    Technical problem In the radar device of Patent Literature 1, the SPAD, which has a higher light reception sensitivity than a conventional photodiode (PD) and an avalanche photodiode (APD), is used as a light receiving element. However, in a distance measuring device for a vehicle, when a projection beam emitted to an object and return light from an object propagate in an external space, it is assumed that ambient light such as sunlight is included. When an amount of ambient light rises, the S / N ratio of a signal decreases, and as a result, a measurable distance and a distance measurement accuracy may not be sufficiently high.
    [0006] In addition, in a distance measuring device for a vehicle, it is necessary to consider points at which a projection beam and return light propagate in an external space. For example, since a projection beam and return light are propagated in a room in which pedestrians and the like travel, it is necessary to devise a method of reducing an influence of the projection beam and return light on a human body. Further, in order to maintain a measurable distance and a distance measurement accuracy even in rainy weather, it is also necessary to examine the light absorption characteristics of the projection beam and the return light with respect to water.
    The present invention has been made to solve the above problems, and the object of the present invention is to provide a distance measuring device in which a measurable distance and the measuring distance accuracy can be confirmed, and which is suitable for a vehicle.
    Problem Solving A distance measuring device according to the present invention is configured to measure a distance to an object. The distance measuring device includes a light source configured to emit a projection beam to the object; and a light receiving element configured to detect return light of the projection beam reflected by the object. The light source is a laser light source configured to emit pulsed light in an ultraviolet range up to a blue color range as the projection beam, and the light receiving element is an avalanche photo diode that has a spectral sensitivity in an ultraviolet range up to a blue color range and works in a violinist mode.
    The energy from ambient light such as sunlight tends to be higher on the longer wavelength side of a blue color range and lower on the short wavelength side of a blue color range, within a visible light range. Therefore, when a light receiving element with spectral sensitivity in an ultraviolet range up to a blue color range is used, it is possible to reduce an influence of ambient light when return light from the object is detected. If an influence of ambient light is reduced and return light is detected in an avalanche photo diode that works in a Geiger mode, it is possible to ensure a sufficient S / N ratio for a signal and to increase a measurable distance and distance measurement accuracy. In addition, for light from an ultraviolet range to a blue color range, an absorption coefficient of water is smaller than that for light in the visible light range on the longer wavelength side of a blue color range, and a maximum allowable illumination for the retina of the human eye is higher than that for light in the visible light range on a longer wavelength side of a blue color range. Therefore, when a laser light source configured to emit pulsed light in an ultraviolet range up to a blue color range is used, it is possible to reduce human body influence and distance measurement deterioration due to rainy weather.
    [0010] The light source may be a laser light source configured to emit pulsed light from 300 nm to 400 nm as a projection beam. If light in this wavelength range is used as the light source, it is possible to optimize conditions that include the absorption coefficient of water and a maximum allowable illumination for the retina of the human eye.
    [0011] In addition, the light receiving element may be a silicon photomultiplier tube. A silicon photomultiplier tube has sufficient spectral sensitivity in an ultraviolet range to a blue color range and functions that are suitable as an avalanche photodiode operating in a Geiger mode.
    Advantageous Effects of the Invention In the distance measuring device, it is possible to increase a measurable distance and distance measuring accuracy, and the device is suitable for a vehicle.
    Brief Description of Drawings [0013]
    1 is a diagram showing an embodiment of a distance measuring device.
    2 is a perspective view showing an example of a configuration of a light receiving element.
    FIG. 3 is a sectional view taken along III-III in FIG. 2.
    Fig. 4 is a graph showing spectral sensitivity characteristics of an MPPC.
    Fig. 5 is a graph showing the influence of ambient light.
    Fig. 6 is a graph showing a maximum allowable exposure for the retina of the human body.
    Fig. 7 is a graph showing light absorption characteristics for water.
    Fig. 8 is a diagram showing a suitable wavelength range used in a distance measuring device.
    DESCRIPTION OF EMBODIMENTS Exemplary embodiments of a distance measuring device according to the present invention will be described below in detail with reference to the drawings.
    Fig. 1 is a perspective view showing an embodiment of a distance measuring device. A distance measuring device 1 is a device that is mounted, for example, as an automatic driving support system in a vehicle such as an automobile. In the automatic driving support system, a distance between a vehicle that is traveling and an object K is measured in real time by the distance measuring device 1, a vehicle speed is controlled based on the measurement result, and a control to avoid collision between the vehicle and the object K is performed , The object K is, for example, another vehicle, an obstacle, such as a wall, or a pedestrian. In the present embodiment, it is assumed, for example, that a distance is measured from an object K that is positioned approximately 0.1 m to 100 m away.
    As shown in Fig. 1, the distance measuring device 1 includes a light source 11, a collimator 12, an aperture 13, a beam splitter 14, a scanning mirror 15, a wavelength selection filter 16, a condenser lens 17 and a light receiving element 18. These components are assembled, for example, on a substantially plate-shaped stage.
    [0017] The light source 11 is a unit configured to emit a projection beam L1 to the object K. As the light source 11, a laser diode configured to emit pulsed light in an ultraviolet range to a blue color range is used. The wavelength of the projection beam L1 is, for example, 300 nm to 500 nm, preferably 300 nm to 400 nm and more preferably 350 nm to 400 nm. The projection beam L1, which is emitted from the light source 11, is collimated by the collimator 12 and becomes a beam splitter 14 out, while a beam diameter is reduced to 10 mm or less through the aperture 13, for example.
    The projection beam L1, which has passed the beam splitter 14, is directed to the scanning mirror 15. The scanning mirror 15 is, for example, a microelectronic mechanical system (MEMS) mirror. The scanning mirror 15 oscillates in a plane direction on a stage 9, based on the control by a control unit (not shown), and scans towards the object K in the direction of the projection beam L1. The diameter of the mirror part of the scanning mirror 15 is, for example, approximately the same as the diameter of the projection beam L1. An oscillation angle of the scanning mirror 15 is, for example, approximately ± 30 °. In addition, a scanning speed of the scanning mirror 15 is, for example, about 0.1 kHz to 10 kHz.
    In addition, the scanning mirror 15 reflects return light L2, which is obtained when the projection beam L1 is reflected by the object K to the beam splitter 14. The return light L2, which is reflected by the beam splitter 14, passes through the wavelength selection filter 16 and is then condensed on a light receiving surface of the light receiving element 18 through the condenser lens 17. The wavelength selection filter 16 is a bandpass filter through which light with a wavelength corresponding to spectral sensitivity characteristics of the light receiving element 18 is transmitted and transmits light with a wavelength of 300 nm to 500 nm, for example, but blocks light in other wavelength bands. A transmission band of the wavelength selection filter 16 can be suitably set according to the wavelength of light emitted from the light source 11.
    [0020] The light receiving element 18 is a unit configured to detect the return light L2 from the object K. An avalanche photodiode operating in a Geiger mode is used as the light receiving element 18. The Geiger mode is a mode in which an operation is performed on a reverse avalanche photodiode voltage set at a breakdown voltage or higher. In a high electric field in a Geiger mode, a discharge phenomenon (Geiger discharge) occurs even if weak light enters, and an electron multiplication constant is about 105 to 106.
    As the avalanche photodiode, which works in the Geiger mode, a single photon avalanche diode (SPAD) and a multi-pixel photon counter / silicon photomultiplier tube (MPPC) can be used as an example. For example, in the MPPC, pixels of the avalanche photodiode, which works in a Geiger mode, are connected in two dimensions in parallel. A quenching resistor is connected to each pixel and each attenuation resistor is connected to a readout channel. Therefore, when measuring a height (number of events) of a pulse or a charge amount of a pulse which signals from pixels are superimposed on, it is possible to detect the number of photons detected by the MPPC.
    An output signal from the light receiving element 18 is output to a computing unit (not shown). A distance to the object K is calculated in the computing unit on the basis of a time-of-flight (TOF) scheme. That is, the computing unit calculates a distance to the object K on the basis of a difference between a point in time at which a pulse of the projection beam L1 is emitted from the light source 11 and a point in time at which the return light L2 is detected by the light receiving element 18 ,
    Fig. 2 is a perspective view showing an example of a configuration of the light receiving element. In addition, FIG. 3 is a cross-sectional view taken along III-III in FIG. 2. 2 and 3 exemplify a configuration of the MPPC. In addition, an insulation layer 37 shown in FIG. 3 is omitted in FIG. 2 for convenience of illustration.
    As shown in Figs. 2 and 3, the MPPC, which is the light receiving element 18, includes a light receiving surface on a surface side of a semiconductor substrate made of Si. The light receiving surface includes, for example, a plurality of light detection units 30, which are arranged two-dimensionally in a matrix form. A wiring pattern 23C for signal readout, which is patterned in a lattice shape, is arranged on a front surface side of the substrate. The inside of an opening of the grid wiring pattern 23C detects a light detection surface. The light detection units arranged in the light detection surface are connected to the wiring pattern 23C.
    [0025] A bottom electrode 40 is provided on a back surface side of the substrate. When a driving voltage of the light detection unit 30 is applied between the wiring pattern 23C, which is the upper electrode, and the bottom electrode 40, an output signal from the light detection unit 30 can be extracted from the wiring pattern 23C.
    A pn junction consists of a p-type semiconductor region, which forms an anode, and an n-type semiconductor region, which forms a cathode. When a drive voltage is applied to a photodiode so that a potential of the p-type semiconductor region is higher than a potential of the n-type semiconductor region, this is a forward bias voltage. Conversely, when a drive voltage is applied to a photodiode, it is a reverse bias voltage.
    The drive voltage is a reverse bias voltage that is applied to a photodiode, which is constructed from an internal pn junction in the light detection unit 30. When the drive voltage is set to a breakdown voltage of the photodiode or higher, an avalanche breakdown occurs in the photodiode and the photodiode operates in a Geiger mode. Here, even if a forward bias voltage is applied to the photodiode, a light detection function of the photodiode is performed.
    A resistance unit (attenuation resistor) 24, which is electrically connected to one end of the photodiode, is arranged on a front surface side of the substrate. One end of the resistance unit 24 forms a contact electrode 24A, which is electrically connected to one end of the photodiode via a contact electrode made of another material positioned directly below. The other end of the resistance unit 24 is in contact with a wiring pattern 23C for signal reading and forms a contact electrode 24C which is electrically connected thereto. That is, the resistance unit 24 in each of the light detection units 30 includes the contact electrode 24A connected to the photodiode, a resistance layer 24B that continuously extends in the contact electrode 24A in a curved manner, and the contact electrode 24C that goes to a terminal end the resistance layer 24B is continuous. Here, the contact electrode 24A, the resistance layer 24B and the contact electrode 24C are constructed by a resistance layer made of the same resistance material.
    One end of the photodiode included in the light detection unit 30 is connected to the wiring pattern 23C with the same potential in principle at all positions, and the other end thereof is connected to the bottom electrode 40, which is configured to apply a substrate potential , This means that photodiodes are connected in parallel in all of the light detection units 30.
    As shown in Fig. 2, the light detection units 30 all include an n-type first semiconductor layer 32, a p-type second semiconductor layer 33, which form a pn junction with the first semiconductor layer 32 and a high-impurity concentration region 34. A first contact electrode 3A is provided in contact with the high impurity concentration area 34. The high impurity concentration area 34 is a diffuse area formed by diffusing impurities into the second semiconductor layer 33 and having a higher impurity concentration than the second semiconductor layer 33.
    In the present embodiment, the p-type semiconductor layer 33 is formed on the n-type semiconductor layer 32 and the p-type high impurity concentration region 34 is formed on the front surface side of the second semiconductor layer 33. Therefore, a pn junction forming the photodiode is formed between the first semiconductor layer 32 and the second semiconductor layer 33. As a layer structure of the semiconductor substrate, a structure having a conductivity type that is inverted from that of the above structure can be used. In this case, the n-type first semiconductor layer 33 is formed on the p-type first semiconductor layer 32, and the p-type high impurity concentration region 34 is formed on the front surface side of the second semiconductor layer 33.
    [0032] In addition, a pn junction interface can be formed on the surface layer side. In this case, a structure in which the n-type second semiconductor layer 33 is formed on the n-type first semiconductor layer 32 and the p-type high impurity concentration region 34 is formed on the front surface side of the second semiconductor layer 33. With this structure, the pn junction is formed at an interface between the second semiconductor layer 33 and the high-impurity concentration region 34. In such a structure, the conductivity type can be inverted.
    [0033] The light detection units 30 all include an insulating layer 36 formed on the surface of the semiconductor substrate. The surfaces of the second semiconductor layer 33 and the high-impurity concentration region 34 are covered by the insulating layer 36. The insulating layer 36 has a contact hole and a contact electrode 23A is formed in the contact hole. The upper insulating layer 37 is formed on the insulating layer 36 and the contact electrode 23A. The insulating layer 37 has a contact hole which is arranged coaxially with the contact electrode 23A and the contact electrode 24A is formed in the contact hole. The upper insulating layer 37 is formed on the insulating layer 36 and the contact electrode 23A. The insulating layer 37 has a contact hole which is formed coaxially with the contact electrode 23A, and the contact electrode 24A is formed in the contact hole.
    Fig. 4 is a graph showing spectral sensitivity characteristics of the MPPC described above. In Fig. 4, the horizontal axis represents a wavelength and the vertical axis represents photon detection efficiency. In addition, the spectral sensitivity characteristics are determined when an MPPC, which has 400 light detection units and an arrangement distance of the light detection units which is 25 Dm, operates in a Geiger mode with a reverse bias voltage of 74 V. Here the breakdown voltage of the MPPC is 71 V.
    As shown in Fig. 4, the photon detection efficiency in the MPPC has a peak near a wavelength of 450 nm. The photon detection efficiency at a peak wavelength is about 38%. The photon detection efficiency in the MPPC is about 22% to 38% in a wavelength range from 300 nm to 500 nm, about 22% to 35% in a wavelength range from 300 nm to 400 nm and about 29% to 35% in a wavelength range from 350 nm to 400 nm.
    [0036] On the other hand, the photon detection efficiency in the MPPC is about 28% at a wavelength of 600 nm, about 17% at a wavelength of 700 nm and about 9% at a wavelength of 800 nm, and gradually decreases on a longer wavelength side of a blue one color range. Therefore, the MPPC described above is a light receiving element with a high spectral sensitivity in an ultraviolet range up to a blue color range. The reason why the MPPC has a high spectral sensitivity in an ultraviolet range to a blue color range may be due to a structure in which an absorption length of short wavelength light incident on the light receiving surface of the MPPC to the position of the Avalanche layer fits and electrons are injected into the avalanche layer with a high ionization rate. In addition, since a high electric field is applied in a Geiger mode, there is a high possibility that an electric charge is accelerated by the electric field before it is absorbed in the semiconductor layer.
    [0037] Next, operations and effects of the distance measuring device 1 described above will be described.
    As described above, in the distance measuring device 1, the avalanche photodiode, which operates in a Geiger mode, is used as the light receiving element 18. The light receiving element 18 has a higher light receiving sensitivity than a conventional photodiode (PD) or an avalanche photodiode (APD), but is easily influenced by ambient light such as sunlight.
    Here, Fig. 5 is a graph showing the influence of ambient light. In Figure 5, sunlight is exemplified as a major component of ambient light and the horizontal axis represents a wavelength and the vertical axis represents solar energy during the day near the surface of the earth. As shown in Fig. 5, the solar light energy has a peak wavelength close to 500 nm. On a shorter wavelength side and a longer wavelength side of this peak, as the energy of sunlight decreases, moving away from the peak wavelength, a rate of descent thereof is much greater on the shorter wavelength side than on the longer wavelength side.
    Based on this result, it is understood that in the visible light region, the energy of ambient light tends to be higher on the longer wavelength side of a blue color region and lower on the shorter wavelength side of a blue color region. Therefore, when the light receiving element 18 having a spectral sensitivity in an ultraviolet range up to a blue color range is used, it is possible to reduce an influence of ambient light when the return light L2 from the object K is detected. If an influence of ambient light is reduced and return light is detected in the avalanche photodiode, which works in a Geiger mode, it is possible to ensure a sufficient S / N ratio of a signal and to increase a measurable distance and distance measurement accuracy. In addition, if a wavelength range in which the energy of the ambient light is small is selected even if an output of the projection beam L1 emitted from the light source 11 is reduced, it is possible to ensure the sufficient S / N ratio of the signal. Therefore, it is possible to reduce the power consumption of the distance measuring device 1.
    In addition, Fig. 6 is a graph showing a maximum allowable exposure for the retina of the human body. In Fig. 6, the horizontal axis represents a wavelength and the vertical axis represents a maximum permissible exposure (MPE) for the retina. In addition, a maximum permissible exposure of 10 ns is indicated by a solid line in FIG. 6 and a maximum permissible exposure of 1 s is indicated by a dashed line. The maximum allowable exposure of 10 ns is a maximum allowable exposure if an incidence time of a pulse of laser light is 10 ns and the maximum allowable exposure of 1 s is a maximum allowable exposure if an incidence time of a pulse of laser light is 1 s.
    In general, damage to the retina of the human body due to laser light depends on a wavelength, an exposure time and a condensing diameter of laser light incident on the retina. The maximum allowable exposure is defined as a laser light intensity of 1/10 of a level at which an error occurrence rate due to laser emission is 50% in the laser safety standard (JIS C 6802).
    As shown in Fig. 6, both the MPE of 10 ns and the MPE of 1 s, the MPE in a near infrared region is higher than the MPE in a visible light region. The MPE of 10 ns in the visible light range is on the order of 0.01 J / cm 2 to 0.1 J / cm 2 and the MPE of 10 ns in the visible light range is on the order of 100 J / cm 2 to 10,000 J / cm 2 . On the other hand, the MPE of 1 s in a wavelength band of 1400 nm or higher is in the order of 10 J / cm 2 to 10,000 J / cm 2, and the MPE of 1 s in the same band is approximately in the order of 10,000 J / cm 2 . cm 2 .
    In addition, in both the 10 ns MPE and the 1 s MPE, the MPE in an ultraviolet range is higher than the MPE in a visible light range. The MPE of 10 ns in a band with a wavelength of 400 nm or less is in the order of 10 J / cm 2 to 100 J / cm 2 and the MPE of 1 s in the same band is in the order of 10 J / cm 2 up to 10,000 J / cm 2 .
    [0045] Based on the results described above, when a laser light source configured to emit pulsed light in an ultraviolet range to a blue color range when the light source 11 is used, it is possible to ensure sufficient within a maximum allowable exposure for the retina of the human body in relation to the projection beam L1 and the return light L2. In the distance measuring device 1 for a vehicle, as in the present embodiment, the projection beam L1 and the return light L2 propagate in an external space from the distance measuring device 1 to the object K. Since this external space is a space that is walked on by pedestrians and similar traffic, the projection beam L1 and the return light L2 are considered to be emitted to the human body. Therefore, if wavelengths of the projection beam L1 and the return light L2 are selected and are within the maximum allowable exposure, it is possible to realize the safety for the retina of the human body (eye safety).
    Fig. 7 is a graph showing light absorption characteristics for water. In Fig. 7, the horizontal axis represents a wavelength and the vertical axis represents an absorption coefficient. As shown in Fig. 7, an absorption coefficient of water is smallest near a wavelength of 400 nm, which is 10 4 cm 1 or less. Even in a range near a wavelength of 400 nm, the absorption coefficient of water is smaller than in other wavelength ranges and is 10 ^ cm -1 or less in a wavelength range from 300 nm to 500 nm.
    Based on the results described above, when a laser light source configured to emit pulsed light in an ultraviolet range to a blue color range when the light source 11 is used, it is possible to have an influence of the absorption of water to reduce the projection beam L1 and the return light L2. In the distance measuring device 1 for a vehicle, as in the present embodiment, the projection beam L1 and the return light L2 propagate from the distance measuring device 1 to the object K in an external space. When the projection beam L1 and the return light L2 propagate in the external space, it is assumed that depending on the weather, the projection beam L1 and the return light L2 pass through raindrops, fog and the like. Therefore, if wavelengths of the projection beam L1 and the return light L2 are selected so that an influence of the absorption from water is reduced, it is possible to ensure a measurable distance and a distance measurement accuracy regardless of the weather.
    As described above, in the distance measuring device 1, the laser light source configured to emit pulsed light in an ultraviolet example up to a blue color range as the projection beam L1 is used as the light source and the avalanche photodiode, the spectral sensitivity in one has an ultraviolet range up to a blue color range and operates in a Geiger mode when the light receiving element 18 is used. Accordingly, in the distance measuring device 1, it is possible to improve the measurable distance and the distance measurement accuracy by eliminating an influence of ambient light, realizing eye safety and minimizing fluctuation in the measurable distance and the distance measurement accuracy by eliminating an influence of the absorption of water.
    Fig. 8 is a diagram showing a suitable wavelength range used in the distance measuring device. Referring to the graph shown in FIG. 5, a wavelength range suitable for reducing an influence of ambient light is 300 nm to 400 nm. As shown in FIG. 4, the photon detection efficiency in the MPPC is about 22% to 35 % in a wavelength range from 300 nm to 500 nm and a sufficient detection efficiency is shown in this range.
    Referring to the graph shown in Fig. 6, an appropriate wavelength range for realizing eye safety is 300 nm to 400 nm. In addition, referring to the graph shown in Fig. 7, one is suitable for reducing an influence of the absorption of water Wavelength range 300 nm to 400 nm. Based on such results, when a laser light source configured to emit pulsed light from 300 nm to 400 nm as the projection beam L1 is used as the light source 11 and an MPPC (silicon photomultiplier tube) as the light receiving element 18 is used, it is possible to more reliably show the above effects.
    Here, when a laser diode is used as the light source 11, care must be taken because a wavelength of laser light emitted from the laser diode depends on the temperature. In general, a dependence of a wavelength of a laser diode in an ultraviolet range on temperature is approximately an order of magnitude smaller than a dependency on a wavelength of a laser diode in a near infrared range on temperature and is, for example, 0.03 nm / ° C. to 0. 04 nm / ° C. Therefore, even if a temperature range of an environment in which the distance measuring device 1 is used for a vehicle is assumed to be -40 ° C to 105 ° C, an amount of change in the wavelength is several nm or less and is an influence of a wavelength dependency extremely small in temperature.
    In addition, in the present embodiment, as shown in Fig. 4, the photon detection efficiency in the MPPC has a peak near a wavelength of 450 nm. On the other hand, when a wavelength of laser light emitted from the light source 11 is 300 nm to 400 nm, a wavelength of a peak of detection efficiency of the MPPC is longer than a wavelength of laser light. Therefore, even if a temperature of an environment in which the distance measuring device 1 is used shifts to a high temperature side, the detection efficiency of the MPPC increases and it is possible to sufficiently ensure a measurable distance and a distance measuring accuracy.
    LIST OF REFERENCE NUMBERS 1 Distance measuring device 11 light source 18 Light-receiving element
    LIST OF REFERENCE NUMBERS K object L1 projection beam L2 return light
    权利要求:
    Claims (3)
    [1]
    claims
    A distance measuring device (1) configured to measure a distance to an object (K), comprising: a light source (11) configured to emit a projection beam (L1) to the object (K); and a light receiving element (18) configured to detect return light of the projection beam (L1) reflected by the object, the light source (11) being a laser light source configured to have pulsed light in an ultraviolet range to emit up to a blue color range as the projection beam (L1), and the light receiving element (18) is an avalanche photodiode which has a spectral sensitivity in an ultraviolet range up to a blue color range and can operate in a Geiger mode.
    [2]
    2. Distance measuring device (1) according to claim 1, wherein the light source (11) is a laser light source that is configured to emit pulsed light from 300 nm to 400 nm as the projection beam (L1).
    [3]
    3. Distance measuring device (1) according to claim 1 or 2, wherein the light receiving element (18) is a silicon photomultiplier tube.
    Fîg.i
    OBJECT
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    300 400 500 600 700 800 900
    WAVELENGTH (nm)
    WAVELENGTH (nm)
    O
    O
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    O
    IQ
    S, g>
    U.
    W) 3dW iE
    WAVELENGTH
    Fs g. 3
    SUITABLEWAVELENGTH RANGE REDUCE INFLUENCE OF AMBIENT LIGHT 0nm ~ 400nm REALIZE EYE SAFETY 300nm ~ 400nm REDUCE INFLUENCE OF WATER ABSORPTION 3Q0ntn ~ 50Qnm
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    法律状态:
    2022-01-31| PL| Patent ceased|
    优先权:
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    JP2015204658A|JP2017075906A|2015-10-16|2015-10-16|Distance measurement device|
    PCT/JP2016/068398|WO2017064882A1|2015-10-16|2016-06-21|Distance measuring device|
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