JP2018156051A - Laser scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser scanner having high reliability.SOLUTION: The laser scanner includes a light source 11 emitting laser light, a liquid crystal element for partially transmitting the laser light emitted from the light source 11, an optical element 13 for deflecting the laser light transmitted through the liquid crystal element, and a light-receiving element for detecting the laser light reflected by an object. The liquid crystal element has a plurality of regions each of which can be set into one of a transmitting state and a light-shielding state, and transmits laser light in the laser light emitted from the light source, incident to at least one of the plurality of regions.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a laser scanning device mounted on a vehicle, for example, a laser scanning device using an infrared laser.

  Devices for automatically driving vehicles or assisting driving of vehicles have been actively developed. Further, LIDAR (Light Detection and Ranging) mounted on a vehicle or the like is known. LIDAR scans a certain area in front of the vehicle using laser light (for example, wavelength λ = 905 nm), detects the reflected light from the object in this scanning range, and detects the object, and from the vehicle. Measure the distance to the object.

  As the LIDAR scanning method, for example, a method using a polygon mirror, a MEMS (Micro Electro Mechanical Systems) mirror, or a galvanometer mirror is used. However, these methods tend to increase the cost and size of the laser scanning device. For this reason, it is desired to reduce the cost and size of the laser scanning device.

US Pat. No. 8,982,313

  The present invention provides a highly reliable laser scanning device.

  A laser scanning device according to one embodiment of the present invention includes a light source that emits laser light, a liquid crystal element that partially transmits the laser light emitted from the light source, and an optical that refracts the laser light transmitted through the liquid crystal element. An element and a light receiving element that detects laser light reflected by the object are provided.

  A laser scanning device according to an aspect of the present invention includes a light source that emits laser light, a first optical element that emits laser light emitted from the light source, and a first light that focuses the laser light reflected by an object. Two optical elements, a liquid crystal element that partially transmits the laser light transmitted through the second optical element, and a light receiving element that detects the laser light transmitted through the liquid crystal element.

  According to the present invention, a highly reliable laser scanning device can be provided.

1 is a block diagram of a laser scanning device according to a first embodiment of the present invention. The top view of a liquid crystal element and a radiation element. Sectional drawing of the liquid crystal element and radiation element which followed the AA 'line of FIG. Schematic explaining the basic operation of the laser scanning device. The figure explaining the waveform of the laser beam by a laser scanning apparatus. Sectional drawing explaining operation | movement of a liquid crystal element. The schematic sectional drawing explaining an example of a radiation element. The schematic sectional drawing explaining an example of a radiation element. The schematic sectional drawing explaining an example of a radiation element. The schematic sectional drawing explaining an example of a radiation element. The schematic sectional drawing explaining an example of a radiation element. The schematic sectional drawing explaining an example of a radiation element. The schematic sectional drawing explaining an example of a radiation element. The block diagram of the laser scanning apparatus which concerns on 2nd Embodiment of this invention. Sectional drawing of a light source and a radiation element. The top view of a liquid crystal element and a condensing element. FIG. 17 is a cross-sectional view of the liquid crystal element and the light collecting element along the line AA ′ in FIG. 16. Sectional drawing explaining operation | movement of a liquid crystal element.

  Hereinafter, embodiments will be described with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of the drawings are not necessarily the same as actual ones. Further, even when the same portion is represented between the drawings, the dimensional relationship and ratio may be represented differently. In particular, the following embodiments exemplify an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention depends on the shape, structure, arrangement, etc. of components. Is not specified. In the following description, elements having the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

[First Embodiment]
[1] Configuration of Laser Scanning Device FIG. 1 is a block diagram of a laser scanning device 10 according to the first embodiment of the present invention.

  The laser scanning device 10 is also called LIDAR (Light Detection and Ranging). LIDAR scans a certain range, for example, in front of the vehicle using laser light, and detects laser light reflected by an object in this scanning range. The LIDAR then uses the transmitted laser light and the received laser light to detect the object and measure the distance from the vehicle to the object.

  The laser scanning device 10 is provided on the front side of the vehicle (for example, the front bumper or the front grille), the rear side of the vehicle (for example, the rear bumper or the rear grille), and / or the side of the vehicle (for example, the side of the front bumper). Be placed. Further, the laser scanning device 10 may be disposed on an upper portion of the vehicle such as a roof or a bonnet.

  The laser scanning device 10 includes a light source 11, a liquid crystal element 12, a radiation element 13, a light receiving element 14, a pulse timing control unit 15, an emission angle control unit 16, a distance calculation unit 17, and a main control unit 18.

  The light source 11 generates (emits) laser light toward the liquid crystal element 12. As the laser light, for example, infrared laser light (for example, wavelength λ = 905 nm) is used. The light source 11 generates laser light as a pulse signal having a predetermined frequency.

  The liquid crystal element 12 receives the laser light emitted from the light source 11. The liquid crystal element 12 includes a plurality of regions divided into a matrix. The liquid crystal element 12 transmits laser light incident on at least one of the plurality of regions. In other words, the liquid crystal element 12 partially and selectively transmits the laser light emitted from the light source 11. Thereby, the liquid crystal element 12 can set arbitrarily the direction of the laser beam irradiated toward the target object 2 in cooperation with the radiation element 13 described later. A specific configuration of the liquid crystal element 12 will be described later.

  As a basic function, the radiating element 13 radiates laser light incident thereon with a predetermined spread. Specifically, the radiation element 13 refracts the laser light partially transmitted through the liquid crystal element 12 and increases the emission angle of the laser light. As an example, the radiation element 13 is configured by a plano-concave lens. A specific configuration of the radiating element 13 will be described later.

  The light receiving element (detection circuit) 14 detects the laser light reflected by the object 2. The light receiving element 14 is composed of, for example, an infrared sensor. Infrared sensors include photodiodes and CMOS (complementary metal oxide semiconductor) photosensors. In addition, an infrared camera may be used as the light receiving element 14.

  The pulse timing control unit 15 controls the operation of the light source 11. The light source 11 emits laser light (that is, pulsed laser light) as a pulse signal. The pulse timing control unit 15 controls the timing of pulses included in the laser light. The pulse timing includes the period of the pulse signal, the frequency of the pulse signal, and the pulse width.

  The emission angle control unit 16 applies a plurality of voltages to the liquid crystal element 12, and among a plurality of regions included in the liquid crystal element 12, a region that transmits laser light (a transmission region) and a region that blocks laser light (a light shielding region). ) And control. When the optical characteristics of the radiation element 13 are determined, a plurality of refraction angles of the radiation element 13 corresponding to the plurality of regions of the liquid crystal element 12 can be calculated in advance. Therefore, the emission angle of the laser beam that has passed through each of the plurality of regions of the liquid crystal element 12 can be calculated in advance. This information is stored in a memory included in the main control unit 18 as a table, for example. Therefore, the emission angle control unit 16 can set and recognize the emission angle of the laser light emitted from the radiation element 13 by selecting the transmission region of the liquid crystal element 12.

  The distance calculation unit 17 receives the timing information of the transmitted laser beam from the pulse timing control unit 15, receives the information of the emission angle from the emission angle control unit 16, and receives the received timing information and light intensity information of the laser beam. Received from the light receiving element 14. The distance calculation unit 17 calculates the distance from the vehicle to the object using these pieces of information. Specifically, the distance calculation unit 17 calculates a linear distance, a horizontal distance, and a vertical distance using information on the emission angle and the like. In addition, the distance calculation unit 17 calculates the relative coordinates of the object using the information on the emission angle and the like. The distance and / or relative coordinates calculated by the distance calculation unit 17 can be output to the outside as data DOUT, for example.

  The main control unit 18 comprehensively controls the overall operation of the laser scanning device 10.

[2] Configuration of Liquid Crystal Element 12 and Radiation Element 13 Next, the configuration of the liquid crystal element 12 and the radiation element 13 will be described. FIG. 2 is a plan view of the liquid crystal element 12 and the radiation element 13. FIG. 3 is a cross-sectional view of the liquid crystal element 12 and the radiation element 13 taken along the line AA ′ of FIG.

  The liquid crystal element 12 is a transmissive and shutter type liquid crystal panel. The liquid crystal element 12 includes substrates 20 and 21 disposed to face each other and a liquid crystal layer 22 sandwiched between the substrates 20 and 21. Each of the substrates 20 and 21 is composed of a transparent substrate (for example, a glass substrate or a plastic substrate). The substrate 20 is disposed to face the light source 11, and the laser light from the light source 11 enters the liquid crystal layer 22 from the substrate 20 side.

  The liquid crystal layer 22 is filled between the substrates 20 and 21. Specifically, the liquid crystal layer 22 is sealed in a region surrounded by the substrates 20 and 21 and the sealing material 23. The sealing material 23 is made of, for example, an ultraviolet curable resin, a thermosetting resin, or an ultraviolet / heat combination type curable resin, and is applied to the substrate 20 and / or the substrate 21 in the manufacturing process, and then irradiated with ultraviolet rays or heated. Cured.

  The liquid crystal material constituting the liquid crystal layer 22 changes its optical characteristics by manipulating the orientation of liquid crystal molecules in accordance with the voltage (electric field) applied between the substrates 20 and 21. The liquid crystal element 12 of this embodiment is, for example, a TN (Twisted Nematic) mode. That is, a positive (P-type) nematic liquid crystal having positive dielectric anisotropy is used as the liquid crystal layer 22, and the major axis (director) of the liquid crystal molecules is aligned in a substantially horizontal direction when no voltage is applied, and Along the thickness direction (from the substrate 20 toward the substrate 21), the major axis of the liquid crystal molecules is twisted and aligned approximately 90 degrees (or in the range of 60 degrees to 120 degrees). When the voltage is applied, the major axis of the liquid crystal molecules is oriented in a substantially vertical direction. The initial alignment of the liquid crystal layer is controlled by two alignment films (not shown) provided on the substrates 20 and 21 with the liquid crystal layer 22 interposed therebetween.

  A liquid crystal driving method other than the TN mode may be used. For example, as a liquid crystal driving method, a vertical alignment (VA) mode using negative (N-type) nematic liquid crystal may be used. In the VA mode, the major axis of liquid crystal molecules is aligned in a substantially vertical direction when no voltage is applied, and the major axis of the liquid crystal molecules is inclined in the horizontal direction when a voltage is applied. Further, as another liquid crystal driving method, a homogeneous mode using a positive (P-type) nematic liquid crystal may be used. In the homogeneous mode, the major axis of the liquid crystal molecules is aligned in a substantially horizontal direction when no voltage is applied, and the major axis of the liquid crystal molecules is inclined in the vertical direction when a voltage is applied.

  Further, in order to suppress energy loss in the polarizing plate, a polymer dispersed liquid crystal (PDLC) or a polymer network liquid crystal (PNLC) may be used as the liquid crystal element 12. . PDLC or PNLC does not require a polarizing plate and can realize a transmission state and a scattering state.

  A plurality of electrodes 24 each extending in the Y direction are provided on the liquid crystal layer 22 side of the substrate 20. In FIG. 2, five electrodes 24-1 to 24-5 are shown as an example. The number of the electrodes 24 can be set to any number as long as it is two or more. The electrodes 24-1 to 24-5 are electrically separated from each other and can be individually voltage controlled. The interval between the plurality of electrodes 24 is desirably smaller from the viewpoint of miniaturization of the liquid crystal element, and is set to, for example, the minimum processing dimension resulting from the manufacturing process. The electrode 24 is composed of a transparent electrode, and for example, ITO (indium tin oxide) is used as the transparent electrode. One end of the electrode 24 is drawn to the outside of the sealing material 23, and the drawn portion is electrically connected to the emission angle control unit 16.

  A plurality of electrodes 25 each extending in the X direction are provided on the liquid crystal layer 22 side of the substrate 21. In FIG. 2, five electrodes 25-1 to 25-5 are shown as an example. The number of the electrodes 25 can be set to any number as long as it is two or more. The electrodes 25-1 to 25-5 are electrically separated from each other and can be individually voltage controlled. The electrode 25 is composed of a transparent electrode, and for example, ITO is used as the transparent electrode. One end of the electrode 25 is drawn to the outside of the sealing material 23, and the drawn portion is electrically connected to the emission angle control unit 16.

  As can be understood from FIG. 2, the liquid crystal element 12 is a passive matrix system (simple matrix system) and a dot matrix system. That is, the liquid crystal element 12 has a dot matrix pattern. The liquid crystal element 12 can control the liquid crystal alignment for each dot at which one electrode 24 and one electrode 25 intersect. In the example of FIG. 2, one intersection region between the electrode 24 and the electrode 25 is a substantially square, and this intersection region is a unit for controlling the phase of light.

  The polarizing plates 26 and 27 are disposed so as to sandwich the substrates 20 and 21. Each of the polarizing plates (linear polarizers) 26 and 27 has a transmission axis and an absorption axis orthogonal to each other in a plane orthogonal to the light traveling direction. Each of the polarizing plates 26 and 27 transmits linearly polarized light (linearly polarized light component) having a vibration surface parallel to the transmission axis out of light having a vibration surface in a random direction, and is a vibration surface parallel to the absorption axis. It absorbs linearly polarized light (linearly polarized light component). The polarizing plates 26 and 27 are arranged so that their absorption axes are parallel to each other, that is, in a parallel Nicol state.

  In addition, the angle which prescribes | regulates the polarizing plate mentioned above shall contain the error which can implement | achieve a desired operation | movement, and the error resulting from a manufacturing process. For example, the orthogonality mentioned above includes a range of 90 ° ± 5 °, and the parallel includes a range of ± 5 °.

  The radiation element 13 is provided on the opposite side of the polarizing plate 27 from the substrate 21. As described above, the radiating element 13 is composed of, for example, a plano-concave lens. The outer shape of the radiating element 13 is not limited to a quadrangle, and may be a circle.

  The radiation element 13 refracts the laser light transmitted through the liquid crystal element 12 and emits the laser light in a wider range (with a predetermined radiation angle). The spread (radiation angle or solid angle) of the laser light emitted from the radiation element 13 is a scanning range of the laser scanning device 10. The radiation angle means a spread angle of outgoing light when viewed in one dimension. When viewed in three dimensions, the state of radiation is represented by a solid angle.

  Various optical elements can be used as the radiation element 13 as long as it has a function of emitting laser light at a predetermined radiation angle. The fixing method of the radiation element 13 and the liquid crystal element 12 can be designed arbitrarily. When the radiating element 13 is in contact with the liquid crystal element 12, a transparent adhesive may be used to bond each other. The radiating element 13 and the liquid crystal element 12 may be arranged with a space therebetween. In this case, for example, the radiation element 13 and the liquid crystal element 12 are fixed at predetermined positions by members (not shown) that support them.

  Note that a transmissive liquid crystal panel (transmissive LCOS) using an LCOS (Liquid Crystal on Silicon) method may be used as the liquid crystal element 12. By using the transmissive LCOS, the electrode can be finely processed, and a smaller liquid crystal element 12 can be realized. In the transmissive LCOS, a silicon substrate (or a silicon layer formed on a transparent substrate) is used. Since the silicon substrate transmits light (including infrared rays) having a wavelength greater than a specific wavelength in relation to the band gap, LCOS can be used as a transmissive liquid crystal panel. By using LCOS, a liquid crystal panel having a smaller electrode size can be obtained, and thus further miniaturization can be achieved. In addition, since the mobility of the liquid crystal molecules is high, the laser beam can be scanned at a high speed.

[3] Operation of Laser Scanning Device 10 [3-1] Basic Operation of Laser Scanning Device 10 First, the basic operation of the laser scanning device 10 will be described. FIG. 4 is a schematic diagram illustrating the basic operation of the laser scanning device 10. In FIG. 4, the laser scanning device 10 is provided on the front side of the vehicle 1, and an example in which the laser scanning device 10 scans the front of the vehicle 1 in the horizontal direction is shown as an example.

  The liquid crystal element 12 and the radiation element 13 included in the laser scanning device 10 transmit laser light in the range of the angle α. The light receiving element 14 detects the laser light reflected by the object 2. The distance L to the assumed object and the scanning range R at the distance L are assumed. For example, when the angle α = 10 degrees and the distance L = 10 m, the scanning range R = 1.7 m, and when the angle α = 10 degrees and the distance L = 50 m, the scanning range R = 8.7 m. is there. The angle α, the distance L, and the scanning range R can be arbitrarily designed according to specifications required for the laser scanning device 10.

  FIG. 5 is a diagram for explaining the waveform of the laser beam by the laser scanning device 10. The upper side of FIG. 5 is a transmission waveform, and the lower side is a reception waveform. The horizontal axis in FIG. 5 is time, and the vertical axis in FIG. 5 is intensity (light intensity).

  The light source 11 emits a laser beam composed of a pulse signal. That is, the light source 11 emits laser light in a time division manner. The pulse timing control unit 15 controls the operation of the light source 11 and controls the period and pulse width of the laser light. The laser scanning device 10 transmits laser light as a pulse signal.

  It is assumed that the pulse signal has a period P and a pulse width W. A delay amount Δ, which is a time from when one pulse is transmitted to when a pulse reflected by an object is received, and a light velocity C are set. The delay amount Δ is calculated by “Δ = 2L / C”. The distance calculation unit 17 calculates the distance from the vehicle 1 to the object 2 using the delay amount Δ.

  For example, it is assumed that the pulse width W = 10 nsec and the period P = 10 μsec (that is, the frequency f = 100 kHz). When the delay amount Δ = 67 nsec, the distance L = 10 m is calculated. By such an operation, the object can be detected and the distance to the object can be calculated.

[3-2] Operation of Liquid Crystal Element 12 Next, the operation of the liquid crystal element 12 will be described. The emission angle control unit 16 applies a plurality of voltages to the electrodes 24-1 to 24-5 and the electrodes 25-1 to 25-5 included in the liquid crystal element 12 in order to drive the liquid crystal element 12.

  FIG. 6 is a cross-sectional view for explaining the operation of the liquid crystal element 12. The light source 11 emits laser light to the liquid crystal region surrounded by the sealing material 23 in the liquid crystal element 12.

  The emission angle control unit 16 sets, for example, one dot among the plurality of regions (dots) of the liquid crystal element 12 to a transmission state. That is, the emission angle control unit 16 applies a predetermined effective voltage V1 between one electrode 24 and one electrode 25 that form one dot that is desired to be transmitted. The effective voltage V1 is an AC voltage. The effective voltage V1 is a voltage capable of vertically aligning liquid crystal molecules, and is a voltage equal to or higher than the threshold voltage of the liquid crystal.

  In the example of FIG. 6, the emission angle control unit 16 applies the effective voltage V1 between the electrode 24-2 and the electrode 25-3. As a result, at the dots where the electrode 24-2 and the electrode 25-3 intersect, an electric field is applied to the liquid crystal layer, and the liquid crystal layer is substantially vertically aligned (turned on). Therefore, the dot in the on state is in a transmissive state. That is, the laser light that has passed through the polarizing plate 26 does not rotate in the liquid crystal layer and passes through the polarizing plate 27.

  On the other hand, the emission angle control unit 16 is an electrode other than the electrode 24-2 and the electrode 25-3, that is, the electrodes 24-1, 24-3 to 24-5, and the electrodes 25-1, 25-2, and 25. -4, 25-5 is applied with 0V. Alternatively, the emission angle control unit 16 applies a predetermined common voltage to the electrodes 24-1, 24-3 to 24-5, and the electrodes 25-1, 25-2, 25-4, and 25-5. That is, the voltage applied to the two electrodes facing each other across the liquid crystal layer may be the same.

  As a result, an electric field is not applied to the liquid crystal layer at a plurality of dots where the electrodes 24-1, 24-3 to 24-5 and the electrodes 25-1, 25-2, 25-4, and 25-5 intersect. The liquid crystal layer maintains the twisted alignment (becomes off state). Therefore, the dot in the off state is in a light shielding state. That is, the laser light transmitted through the polarizing plate 26 is rotated by 90 degrees in the direction of vibration in the liquid crystal layer and is blocked by the polarizing plate 27. FIG. 6 schematically illustrates liquid crystal molecules viewed from above in the on state and the off state.

  The laser light transmitted through the liquid crystal element 12 is refracted by the radiation element 13 and is emitted from the radiation element 13 at a predetermined emission angle θ. As described above, the emission angle control unit 16 can emit laser light only in a predetermined direction. In addition, by selecting one specific dot out of a plurality of dots arranged in a matrix, that is, in a transmissive state, the object can be scanned two-dimensionally.

  Further, the scanning range (angle α) can be arbitrarily set by adjusting the refractive index and the radius of curvature (focal length) of the radiating element 13, that is, the refraction angle.

[4] Configuration Example of Radiation Element 13 Next, a configuration example of the radiation element 13 will be described. The radiation element 13 may have a configuration other than that described above as long as it can refract laser light. 7 to 13 are schematic cross-sectional views for explaining a configuration example of the radiation element 13.

  In FIG. 7, the radiating element 13 is composed of a biconvex lens. When a biconvex lens is used as the radiating element 13, the laser light transmitted through the liquid crystal element 12 is refracted by the radiating element 13 toward the center of the biconvex lens and is emitted from the radiating element 13 at a predetermined emission angle. In other words, the biconvex lens functions so as to radiate the laser light once it is focused at the focal point.

  In FIG. 8, the radiation element 13 is configured by a plano-convex lens. The plane of the plano-convex lens is disposed so as to face the liquid crystal element 12.

  In FIG. 9, the radiating element 13 is constituted by a plano-convex lens. The convex surface of the plano-convex lens is disposed so as to face the liquid crystal element 12.

  In FIG. 10, the radiating element 13 is composed of a biconcave lens. The biconcave lens can increase the scanning range compared to the plano-concave lens.

  In FIG. 11, the radiating element 13 is arranged so that the plane of the plano-concave lens constituted by a plano-concave lens faces the liquid crystal element 12.

  In FIG. 12, the radiating element 13 is arranged so that the concave surface of the plano-concave lens constituted by a plano-concave lens faces the liquid crystal element 12.

  In FIG. 13, the radiating element 13 is formed of a diffraction grating (transmission type diffraction grating). In the configuration example of FIG. 13, the diffraction grating as the radiation element 13 is disposed between the light source 11 and the liquid crystal element 12. The diffraction grating receives laser light from the light source 11 and emits this laser light. The laser light that has passed through the diffraction grating partially passes through the liquid crystal element 12.

  In addition to the configuration example described above, a cylindrical lens, a Fresnel lens, a refractive index distribution lens, or the like may be used as the radiation element 13.

  Thus, various optical elements can be used as the radiating element 13, and the scanning angle can be adjusted according to the optical element to be used.

  In addition, the structure which fixes the liquid crystal element 12 and the radiation element 13 is not specifically limited, It can design arbitrarily.

[5] Effects of First Embodiment As described in detail above, in the first embodiment, the laser scanning device 10 partially transmits the light source 11 that emits laser light and the laser light emitted from the light source 11. A liquid crystal element 12 to be refracted, an optical element (radiation element) 13 that refracts the laser light transmitted through the liquid crystal element 12, and a light receiving element 14 that detects the laser light reflected by the object. Further, the liquid crystal element 12 has a plurality of regions each settable to one of a transmission state and a light shielding state, and laser light incident on at least one of the plurality of regions emitted from the light source 11. Permeate.

  Therefore, according to the first embodiment, the laser beam can be emitted while being narrowed down in a specific direction within the predetermined scanning range. Then, by detecting whether or not the laser beam transmitted in a specific direction is reflected by the object, it is possible to determine whether or not the object exists in a specific direction. The distance to the object can be calculated.

  In addition, by preparing one type of effective voltage and applying this effective voltage to the electrodes provided in the liquid crystal element 12, the emission angle of the laser light can be controlled. As a result, the laser beam can be scanned by simple voltage control.

  Further, the scanning range can be changed by changing the refractive index and the radius of curvature (focal length) of the radiating element 13.

  Further, the emission angle of the laser beam can be controlled using the liquid crystal element 12 and the radiation element 13. Thereby, the laser scanning device 10 can be reduced in size and cost.

  Further, the laser scanning device 10 of the present embodiment has no mechanical components and no mechanical movable part. Thereby, the reliability of the laser scanning apparatus 10 can be improved.

[Second Embodiment]
In the second embodiment, laser light is emitted in a wide range on the transmission side, and at least one of a plurality of regions arranged in a matrix is transmitted on the reception side to receive the laser light. . Then, the incident angle of the laser beam reflected by the object is detected according to the region that is in the transmission state.

[1] Configuration of Laser Scanning Device FIG. 14 is a block diagram of a laser scanning device 10 according to the second embodiment of the present invention. The laser scanning device 10 includes a light source 11, a radiation element 13, a condensing element 30, a liquid crystal element 12, a light receiving element 14, a pulse timing control unit 15, an incident angle control unit 31, a distance calculation unit 17, and a main control unit 18. .

  The radiating element 13 refracts the laser light from the light source 11 and radiates the laser light in a wider range (with a predetermined radiation angle). As an example, the radiation element 13 is configured by a plano-concave lens.

  FIG. 15 is a cross-sectional view of the light source 11 and the radiating element 13. The radiating element 13 is composed of a plano-concave lens, and the plane side of the plano-concave lens faces the light source 11. The radiation element 13 radiates laser light from the light source 11 in a wider range. The spread (radiation angle or solid angle) of the laser light emitted from the radiation element 13 becomes the scanning range of the laser scanning device 10. As long as the radiation element 13 has a function of emitting laser light, various optical elements can be used. The radiating element 13 may be a biconvex lens, a plano-convex lens, a biconcave lens, a diffraction grating, a cylindrical lens, a Fresnel lens, or a refractive index distribution lens. That is, the same configuration example as the radiation element described in the first embodiment is applied to the radiation element 13.

  The condensing element 30 refracts the laser light reflected by the object and condenses the laser light toward the liquid crystal element 12. Further, the converging angle of the condensing element 30 is set so that the laser light is incident on the liquid crystal element 12 substantially perpendicularly.

  The liquid crystal element 12 receives the laser light refracted by the light condensing element 30. The position where the liquid crystal element 12 is arranged is different from that of the first embodiment, but the configuration of the liquid crystal element 12 is the same as that of the first embodiment. That is, the liquid crystal element 12 includes a plurality of regions divided into a matrix. The liquid crystal element 12 sets at least one of the plurality of regions to a transmission state, and transmits the laser light when the laser light is incident on the transmission state region. In other words, the liquid crystal element 12 partially and selectively transmits the laser light from the light condensing element 30. Since the incident angle of the laser beam can be specified according to the region that is in the transmission state, the direction in which the object exists can be specified. A specific configuration of the liquid crystal element 12 will be described later.

  The light receiving element 14 detects the laser light transmitted through the liquid crystal element 12.

  The incident angle control unit 31 applies a plurality of voltages to the liquid crystal element 12, and among a plurality of regions included in the liquid crystal element 12, a region that transmits laser light (a transmission region) and a region that blocks laser light (a light shielding region). ) And control. The incident angle control unit 31 can recognize in advance the refraction angle by the light collecting element 30 according to the optical characteristics of the light collecting element 30. Further, the incident angle control unit 31 can recognize in advance the incident angles of the laser beams respectively transmitted through the plurality of regions of the liquid crystal element 12 according to the refraction angle by the condensing element 30. This information is stored in a memory included in the main control unit 18 as a table, for example. Therefore, the incident angle control unit 31 can recognize the incident angle of the laser light reflected by the object by selecting the transmission region of the liquid crystal element 12.

  Other configurations are the same as those of the first embodiment.

[2] Configuration of Liquid Crystal Element 12 and Condensing Element 30 Next, the configuration of the liquid crystal element 12 and the condensing element 30 will be described. FIG. 16 is a plan view of the liquid crystal element 12 and the condensing element 30. FIG. 17 is a cross-sectional view of the liquid crystal element 12 and the condensing element 30 along the line AA ′ in FIG. 16.

  Similarly to the first embodiment, the liquid crystal element 12 includes substrates 20 and 21, a liquid crystal layer 22, a sealing material 23, a plurality of electrodes 24 (electrodes 24-1 to 24-5), and a plurality of electrodes 25 (electrodes 25-1). 25-5), and polarizing plates 26 and 27.

  A condensing element 30 is provided on the opposite side of the polarizing plate 27 from the substrate 21. As described above, the condensing element 30 is configured by a plano-concave lens, for example. The outer shape of the light collecting element 30 is not limited to a quadrangle, and may be a circle.

  It is desirable that the incident angle of the condensing element 30 is substantially the same as the emission angle of the radiating element 13. The refractive index and the radius of curvature of the condensing element 30 are set so as to satisfy the above conditions, and the combination of the refractive index and the radius of curvature can be arbitrarily designed. For example, the condensing element 30 is composed of the same optical element as the radiating element 13. In order to increase the detection sensitivity, it is desirable that the area of the light collecting element 30 is as large as possible. The size of the liquid crystal element 12 is set to be approximately the same as the size of the light collecting element 30.

  In addition, the incident angle of the condensing element 30 may not be completely the same as the emission angle of the radiation element 13, and some difference is permitted. When the incident angle of the condensing element 30 and the emission angle of the radiating element 13 are different, the laser light transmitted through the liquid crystal element 12 is not perpendicular to the liquid crystal element 12 (the substrate surface of the liquid crystal element 12). However, even if the laser beam transmitted through the liquid crystal element 12 is not perpendicular to the liquid crystal element 12, the function of the present embodiment can be realized as long as the laser beam is tilted within a range that can transmit the transmissive dots. .

  As the condensing element 30, a plano-concave lens, a biconvex lens, a plano-convex lens, a biconcave lens, a diffraction grating, a cylindrical lens, a Fresnel lens, or a refractive index distribution lens may be used. For example, when a plano-concave lens is used as the condensing element 30, the surface facing the liquid crystal element 12 may be a flat surface or a concave surface. The same applies to other optical elements.

[3] Operation of Liquid Crystal Element 12 Next, the operation of the liquid crystal element 12 will be described. The incident angle control unit 31 applies a plurality of voltages to the electrodes 24-1 to 24-5 and the electrodes 25-1 to 25-5 included in the liquid crystal element 12 in order to drive the liquid crystal element 12.

  FIG. 18 is a cross-sectional view for explaining the operation of the liquid crystal element 12. The condensing element 30 refracts the laser light reflected by the object, and condenses the laser light on the liquid crystal element 12 so that the laser light enters the liquid crystal element 12 substantially perpendicularly.

  The incident angle control unit 31 sets, for example, one dot among a plurality of regions (dots) of the liquid crystal element 12 to a transmission state. That is, the incident angle control unit 31 applies a predetermined effective voltage V <b> 1 between one electrode 24 and one electrode 25 that form one dot that is to be transmitted.

  In the example of FIG. 18, the incident angle control unit 31 applies the effective voltage V1 between the electrode 24-2 and the electrode 25-3. As a result, at the dots where the electrode 24-2 and the electrode 25-3 intersect, an electric field is applied to the liquid crystal layer, and the liquid crystal layer is substantially vertically aligned (turned on). Therefore, the dot in the on state is in a transmissive state. That is, the laser beam that has passed through the polarizing plate 27 passes through the polarizing plate 26 without rotating in the vibration direction in the liquid crystal layer.

  On the other hand, the incident angle control unit 31 is an electrode other than the electrode 24-2 and the electrode 25-3, that is, the electrodes 24-1, 24-3 to 24-5, and the electrodes 25-1, 25-2, and 25. -4, 25-5 is applied with 0V. Alternatively, the incident angle control unit 31 applies a predetermined common voltage to the electrodes 24-1, 24-3 to 24-5, and the electrodes 25-1, 25-2, 25-4, and 25-5.

  As a result, an electric field is not applied to the liquid crystal layer at a plurality of dots where the electrodes 24-1, 24-3 to 24-5 and the electrodes 25-1, 25-2, 25-4, and 25-5 intersect. The liquid crystal layer maintains the twisted alignment (becomes off state). Therefore, the dot in the off state is in a light shielding state. That is, the laser beam transmitted through the polarizing plate 27 is rotated by 90 ° in the liquid crystal layer and is blocked by the polarizing plate 26.

  The incident angle control unit 31 can calculate the incident angle θ corresponding to the dot in the transmissive state. Therefore, when the light receiving element 14 detects the laser beam, the main control unit 18 can recognize that the object exists in the direction of the incident angle corresponding to the transmissive dot. On the other hand, when the light receiving element 14 does not detect the laser beam, the main control unit 18 can recognize that there is no object in the direction of the incident angle corresponding to the transmissive dot.

  Further, the incident angle control unit 31 can substantially scan the object in two dimensions by sequentially changing the dots in the transmission state. The scanning range (angle α) can be arbitrarily set by adjusting the refractive index and the radius of curvature (focal length) of the radiating element 13 and the condensing element 30, that is, the refraction angle.

[4] Effects of the Second Embodiment As described in detail above, in the second embodiment, the laser scanning device 10 includes the light source 11 that emits laser light and the first optical that emits the laser light emitted from the light source 11. An element (radiating element) 13, a second optical element (condensing element) 30 that condenses the laser light reflected by the object, and a liquid crystal element 12 that partially transmits the laser light that has passed through the condensing element 30. And a light receiving element 14 for detecting the laser light transmitted through the liquid crystal element 12. In addition, the liquid crystal element 12 has a plurality of regions each of which can be set to one of a transmission state and a light shielding state, and is incident on at least one of the plurality of regions of the laser light transmitted through the condensing element 30. Transmit light.

  Therefore, according to the second embodiment, laser light can be incident (transmitted) while being narrowed down in a specific direction within a predetermined scanning range. Then, by detecting whether or not the laser beam is reflected by the object in a specific direction, it can be determined whether or not the object exists in the specific direction, and when the object exists, The distance to the object can be calculated.

  Further, the scanning range can be changed by changing the refractive index and the radius of curvature (focal length) of the radiating element 13 and the condensing element 30. Other effects are the same as those of the first embodiment.

  In each of the above-described embodiments, the configuration example in which scanning is performed in two dimensions has been described. However, the scanning may be performed in one dimension. In this case, it can be realized by configuring the liquid crystal element 12 to have a plurality of regions arranged in the X direction.

  In each of the above embodiments, the liquid crystal element 12 is configured by a simple matrix method, but other structures (electrode structures) may be applied. As the liquid crystal element 12, a liquid crystal element that is arranged in a matrix shape and can be set in one of a plurality of regions in a transmission state and the other in a light shielding state, that is, a liquid crystal element having an arbitrary optical shutter method can be used. . For example, a liquid crystal element that drives a rectangular electrode corresponding to each of a plurality of regions with a switching element (for example, a TFT (Thin Film Transistor)) may be used.

  In each of the above embodiments, an infrared laser is used as the laser beam handled by the laser scanning device. However, the present invention is not limited to this, and the laser scanning device according to the present embodiment can be applied to light other than infrared light.

  In the above embodiment, a laser scanning device mounted on a vehicle has been described. However, the present invention is not limited to this, and can be applied to various electronic devices having a function of scanning with laser light.

  In the present specification, the term “parallel” is preferably completely parallel, but is not necessarily strictly parallel, and includes those that can be regarded as substantially parallel in view of the effects of the present invention. An error that may occur in the manufacturing process may be included. In addition, “vertical” does not necessarily have to be strictly vertical, and includes what can be regarded as substantially vertical in view of the effects of the present invention, and may include errors that may occur in the manufacturing process. Good.

  In this specification, a board and a film are the expressions which illustrated the member, and are not limited to the structure. For example, the polarizing plate is not limited to a plate-like member, and may be a film having other functions described in the specification or other members.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the embodiments may be implemented in combination as appropriate, and in that case, the combined effect can be obtained. Furthermore, the present invention includes various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if several constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the problem can be solved and an effect can be obtained, the configuration from which the constituent requirements are deleted can be extracted as an invention.

  DESCRIPTION OF SYMBOLS 10 ... Laser scanning apparatus, 11 ... Light source, 12 ... Liquid crystal element, 13 ... Radiation element, 14 ... Light receiving element, 15 ... Pulse timing control part, 16 ... Output angle control part, 17 ... Distance calculation part, 18 ... Main control part , 20, 21 ... substrate, 22 ... liquid crystal layer, 23 ... sealing material, 24, 25 ... electrode, 26, 27 ... polarizing plate, 30 ... condensing element, 31 ... incident angle control unit

Claims (6)

A light source that emits laser light;
A liquid crystal element that partially transmits laser light emitted from the light source;
An optical element that refracts laser light transmitted through the liquid crystal element;
A laser scanning device comprising: a light receiving element that detects a laser beam reflected by an object. The liquid crystal element has a plurality of regions each of which can be set to one of a transmission state and a light shielding state, and is configured to emit laser light incident on at least one of the plurality of regions out of the laser light emitted from the light source. The laser scanning device according to claim 1, wherein the laser scanning device is transmitted. A light source that emits laser light;
A first optical element that emits laser light emitted from the light source;
A second optical element for condensing the laser light reflected by the object;
A liquid crystal element that partially transmits laser light transmitted through the second optical element;
A laser scanning device comprising: a light receiving element that detects laser light transmitted through the liquid crystal element. The liquid crystal element has a plurality of regions each of which can be set to one of a transmission state and a light-shielding state, and is incident on at least one of the plurality of regions of the laser light transmitted through the second optical element. The laser scanning device according to claim 3, wherein light is transmitted. The laser scanning device according to claim 1, wherein the liquid crystal element has a passive matrix method. The liquid crystal element is
First and second substrates;
A liquid crystal layer filled between the first and second substrates;
A plurality of first electrodes provided on the first substrate, each extending in a first direction;
A plurality of second electrodes provided on the second substrate, each extending in a second direction intersecting the first direction;
The laser scanning device according to claim 1, further comprising: first and second polarizing plates provided so as to sandwich the first and second substrates.