JP6953754B2 - Laser scanning device - Google Patents

Description

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

Equipment for automatic driving of vehicles or driving support for vehicles is being actively developed. In addition, LIDAR (Light Detection and Ranging) mounted on vehicles and the like is known. LIDAR uses laser light (for example, wavelength λ = 905 nm) to scan a certain area in front of the vehicle, and detects the reflected light from the object in this scanning range to detect the object and from the vehicle. Measure the distance to the object.

As the scanning method of LIDAR, for example, a method using a polygon mirror, a MEMS (Micro Electro Mechanical Systems) mirror, or a galvano mirror is used. However, in these methods, the laser scanning apparatus tends to be expensive and large in size. Therefore, it is desired to reduce the cost and size of the laser scanning apparatus.

U.S. Pat. No. 8,982,313

The present invention provides a highly reliable laser scanning apparatus.

The laser scanning apparatus according to one aspect of the present invention includes a light source that emits laser light, and a deflection element that includes laminated first and second liquid crystal panels and refracts the laser light from the light source. The first liquid crystal panel was filled between the first and second substrates, the first and second electrodes provided on the first and second substrates and facing each other, and the first and second substrates. Includes a first liquid crystal layer. The second liquid crystal panel was filled between the third and fourth substrates, the third and fourth electrodes provided on the third and fourth substrates and facing each other, and the third and fourth substrates. Includes a second liquid crystal layer. In the first direction of scanning the laser beam, the first electrode is longer than the third electrode.

According to the present invention, it is possible to provide a highly reliable laser scanning device.

The block diagram of the laser scanning apparatus which concerns on embodiment. The plan view of one liquid crystal panel included in a deflection element. FIG. 2 is a cross-sectional view of the deflection element along the AA'line of FIG. The schematic diagram explaining the basic operation of a laser scanning apparatus. The figure explaining the waveform of the laser light by a laser scanning apparatus. The figure explaining the scanning area AR of a laser scanning apparatus. FIG. 5 is a cross-sectional view illustrating the operation of the deflection element according to the first example. FIG. 2 is a cross-sectional view illustrating the operation of the deflection element according to the second example. The cross-sectional view explaining the operation of the deflection element which concerns on 3rd example. FIG. 5 is a cross-sectional view illustrating the operation of the deflection element according to the fourth example. FIG. 5 is a cross-sectional view illustrating the operation of the deflection element according to the fifth example.

Hereinafter, embodiments will be described with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of each drawing are not necessarily the same as the actual ones. Further, even when the same part is represented between the drawings, the relationship and ratio of the dimensions of each other may be represented differently. In particular, some embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and depending on the shape, structure, arrangement, etc. of the components, the technical idea of the present invention. Is not specified. In the following description, elements having the same function and configuration are designated by the same reference numerals, and duplicate explanations will be given only when necessary.

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

The laser scanning device 10 is also called LIDAR (Light Detection and Ranging). LIDAR uses laser light (for example, wavelength λ = 905 nm) to scan a certain area in front of the vehicle, for example, and detects the laser light reflected by an object in this scanning range. Then, LIDAR uses the transmitted laser beam and the received laser beam to detect the object and measure the distance from the vehicle to the object.

The laser scanning device 10 is mounted 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 arranged on the upper part of the vehicle such as a roof or a bonnet.

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

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

The deflection element 12 receives the laser light from the light source 11 and scans the laser light, that is, changes the emission angle of the laser light in a time division manner. As a result, it is possible to irradiate the object 2 with laser beams at a plurality of points. The deflection element 12 includes a plurality of laminated liquid crystal panels. The specific configuration of the deflection element 12 will be described later.

The light receiving element (detection circuit) 13 detects the laser beam reflected by the object 2. The light receiving element 13 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 13.

The pulse timing control unit 14 controls the operation of the light source 11. The light source 11 emits laser light as a pulse signal. The pulse timing control unit 14 controls the timing of the pulse included in the laser beam. The timing of the pulse includes the period of the pulse signal, the frequency of the pulse signal, and the pulse width.

The deflection angle control unit 15 controls the operation of the deflection element 12. The deflection angle control unit 15 applies a plurality of voltages to the plurality of electrodes included in the deflection element 12. The voltage supplied to the deflection element 12 is an AC voltage. The deflection angle control unit 15 controls the deflection angle of the laser light emitted from the deflection element 12 by controlling the gradient of the refractive index of the deflection element 12.

The distance calculation unit 16 receives timing information from the pulse timing control unit 14, deflection angle information from the deflection angle control unit 15, and receives timing information and light intensity information of the received laser light from the light receiving element 13. The distance calculation unit 16 uses this information to calculate the distance from the vehicle to the object. Specifically, the distance calculation unit 16 calculates the linear distance, the horizontal distance, and the vertical distance by using the information of the deflection angle. Further, the distance calculation unit 16 calculates the relative coordinates of the object by using the information of the deflection angle. The distance and / or relative coordinates calculated by the distance calculation unit 16 can be output to the outside as, for example, data DOUT.

The main control unit 17 comprehensively controls the overall operation of the laser scanning device 10.

[2] Configuration of Deflection Element 12 Next, the configuration of the deflection element 12 will be described. FIG. 2 is a plan view of one liquid crystal panel 20-1 included in the deflection element 12. FIG. 3 is a cross-sectional view of the deflection element 12 along the AA'line of FIG.

The deflection element 12 includes a plurality of liquid crystal panels 20. In this embodiment, a configuration example in which the deflection element 12 includes three liquid crystal panels 20-1 to 20-3 will be described. The number of the liquid crystal panels 20 is not limited to three, and may be two or more.

The liquid crystal panels 20-1 to 20-3 are laminated in order and adhered to each other by a transparent adhesive (not shown). In the description of the present embodiment, when it is not necessary to distinguish between the plurality of liquid crystal panels 20-1 to 20-3, the branch number is omitted, and the description of the reference code without the branch number is described. It is common to each of the plurality of liquid crystal panels 20-1 to 20-3. Reference codes with other branch numbers are treated in the same way.

The liquid crystal panel 20-1 is a transmissive liquid crystal panel. The liquid crystal panel 20-1 includes substrates 21-1 and 22-1 arranged to face each other and a liquid crystal layer 23-1 sandwiched between the substrates 21-1 and 22-1. Each of the substrates 21-1 and 22-1 is composed of a transparent substrate (for example, a glass substrate or a plastic substrate). The substrate 21-1 is arranged to face the light source 11, and the laser light from the light source 11 is incident on the liquid crystal layer 23-1 from the substrate 21-1 side.

The liquid crystal layer 23-1 is filled between the substrates 21-1 and 22-1. Specifically, the liquid crystal layer 23-1 is enclosed in a region surrounded by the substrates 21-1, 22-1, and the sealing material 24-1. The sealing material 24-1 is made of, for example, an ultraviolet curable resin, a thermosetting resin, an ultraviolet / heat combined type curable resin, or the like, and is applied to the substrate 21-1 and / or the substrate 22-1 in the manufacturing process, and then is subjected to ultraviolet rays. It is cured by irradiation or heating.

The liquid crystal material constituting the liquid crystal layer 23-1 changes its optical characteristics by manipulating the orientation of the liquid crystal molecules according to the voltage (electric field) applied between the substrates 21-1 and 22-1. The liquid crystal panel 20-1 of the present embodiment is, for example, a homogeneous mode. That is, a positive type (P type) nematic liquid crystal having positive dielectric anisotropy is used as the liquid crystal layer 23-1, and the liquid crystal molecules are substantially horizontal to the substrate surface when no voltage (electric field) is applied. Oriented to. In the homogeneous mode, the long axis (director) of the liquid crystal molecule is oriented substantially horizontally when no voltage is applied, and the long axis of the liquid crystal molecule is tilted in the vertical direction when a voltage is applied. The magnitude of the tilt angle changes according to the effective voltage applied. The initial orientation of the liquid crystal layer is controlled by two alignment films (not shown) provided on the substrates 21-1 and 22-1 so as to sandwich the liquid crystal layer 23-1.

As a liquid crystal driving method, a vertical alignment (VA: Vertical Alignment) mode using a negative type (N type) nematic liquid crystal may be used. In the VA mode, the long axis of the liquid crystal molecules is substantially oriented in the vertical direction when no electric field is applied, and the long axis of the liquid crystal molecules is tilted in the horizontal direction when a voltage is applied. Further, another drive method may be used, and a TN (Twisted Nematic) mode in which the major axis of the liquid crystal molecule is oriented substantially horizontally and twisted at 60 to 120 degrees when no voltage is applied is used. May be good.

A first electrode 25-1 and a second electrode 26-1 are provided on the liquid crystal layer 23-1 side of the substrate 21-1. The length of the first electrode 25-1 in the X direction is predetermined, and the length of the second electrode 26-1 in the X direction is predetermined. The lengths of the first electrode 25-1 and the second electrode 26-1 in the Y direction can be arbitrarily set. The distance between the first electrode 25-1 and the second electrode 26-1 in the X direction is preferably smaller from the viewpoint of miniaturization of the liquid crystal panel, and is set to, for example, the minimum processing dimension due to the manufacturing process. ..

The liquid crystal region surrounded by the sealing material 24-1 (which roughly corresponds to the total region of the first electrode 25-1 and the second electrode 26-1) is optimally set according to the width of the transmitted laser beam. At least, it is set to be larger than the width of the laser beam. The first electrode 25-1 and the second electrode 26-1 are electrically separated from each other, and voltage control is possible individually.

A third electrode 27-1 and a fourth electrode 28-1 are provided on the liquid crystal layer 23-1 side of the substrate 22-1. The third electrode 27-1 faces the first electrode 25-1, and the fourth electrode 28-1 faces the second electrode 26-1. The size of the third electrode 27-1 is substantially the same as the size of the first electrode 25-1, and the third electrode 27-1 is arranged so as to overlap the first electrode 25-1 in a plan view. The size of the fourth electrode 28-1 is substantially the same as the size of the second electrode 26-1, and the fourth electrode 28-1 is arranged so as to overlap the second electrode 26-1 in a plan view. The third electrode 27-1 and the fourth electrode 28-1 are electrically separated from each other, and voltage control is possible individually.

The first electrode 25-1, the second electrode 26-1, the third electrode 27-1, and the fourth electrode 28-1 are respectively located on the liquid crystal panel 20-1 using wiring (not shown) at arbitrary positions. It is pulled out to the outside and electrically connected to the deflection angle control unit 15. The first electrode 25-1, the second electrode 26-1, the third electrode 27-1, and the fourth electrode 28-1 are each composed of transparent electrodes, and examples of the transparent electrodes include ITO (indium tin oxide). Is used.

Similar to the liquid crystal panel 20-1, the liquid crystal panel 20-2 includes substrates 21-2 and 22-2, a liquid crystal layer 23-2, a sealing material 24-2, a first electrode 25-2, and a second electrode 26-2. , A third electrode 27-2, and a fourth electrode 28-2. The liquid crystal panel 20-3 includes substrates 21-3 and 22-3, a liquid crystal layer 23-3, a sealing material 24-3, a first electrode 25-3, a second electrode 26-3, and a third electrode 27-3. , And a fourth electrode 28-3.

The first electrode 25-1, the first electrode 25-2, and the first electrode 25-3 have different lengths in the X direction from each other. The length of the first electrode 25-2 is shorter than the length of the first electrode 25-1, and the length of the first electrode 25-3 is shorter than the length of the first electrode 25-2. In other words, the first electrode 25-1, the first electrode 25-2, and the first electrode 25-3 are formed in a stepped shape so as to be shorter in this order with one end side (right end in FIG. 3) aligned. Will be done. The relationship between the third electrodes 27-1 to 27-3 is the same as the relationship between the first electrodes 25-1 to 25-3.

The second electrode 26-1, the second electrode 26-2, and the second electrode 26-3 have different lengths in the X direction from each other. The length of the second electrode 26-2 is longer than the length of the second electrode 26-1, and the length of the second electrode 26-3 is longer than the length of the second electrode 26-2. In other words, the second electrode 26-1, the second electrode 26-2, and the second electrode 26-3 are arranged in an inverted step shape so as to be longer in this order with one end side (the left end in FIG. 3) aligned. It is formed. The relationship between the fourth electrodes 28-1 to 28-3 is the same as the relationship between the second electrodes 26-1 to 25-3.

By adopting the electrode structure as shown in FIG. 3, it is possible to easily form a gradient of the refractive index when viewed as a whole of the deflection element 12 in which the three liquid crystal panels 20-1 to 20-3 are laminated. ..

The first electrode 25-1 to 25-3 and the third electrode 27-1 to 27-3 are formed in an inverted stepped shape, and the second electrode 26-1 to 26-3 and the fourth electrode 28-1 to 28 are formed. -3 may be formed in a stepped shape. Even with such an electrode structure, the same operation as in FIG. 3 can be realized.

Further, as the liquid crystal panel 20, a transmissive liquid crystal panel (transmissive LCOS) using an LCOS (Liquid Crystal on Silicon) method may be used. By using the transmissive LCOS, the electrodes can be finely processed, and a smaller liquid crystal panel 20 can be realized. In the transmissive LCOS, a silicon substrate (or a silicon layer formed on the transparent substrate) is used. Since the silicon substrate transmits light (including infrared rays) having a wavelength equal to or higher 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, so that the size can be further reduced. Further, since the mobility of the liquid crystal molecules is high, it is possible to scan the laser beam at high speed.

[3] Operation of the laser scanning device 10 [3-1] Basic operation of the laser scanning device 10 First, the basic operation of the laser scanning device 10 will be described. FIG. 4 is a schematic view illustrating the basic operation of the laser scanning device 10. Note that FIG. 4 shows, as an example, a mode in which the laser scanning device 10 is provided on the front side of the vehicle 1 and the laser scanning device 10 scans the front of the vehicle 1 in the horizontal direction.

The light source 11 and the deflection element 12 included in the laser scanning device 10 transmit laser light within a range of an angle θ. The light receiving element 13 detects the laser beam reflected by the object 2. Let it be the distance L to the assumed object and the scanning range R at the distance L. For example, when the angle θ = 10 degrees and the distance L = 10 m, the scanning range R = 1.7 m, and when the angle θ = 10 degrees and the distance L = 50 m, the scanning range R = 8.7 m. be. The angle θ, the distance L, and the scanning range R can be arbitrarily designed according to the specifications required for the laser scanning apparatus 10.

FIG. 5 is a diagram illustrating a waveform of laser light generated by the laser scanning device 10. The upper side of FIG. 5 is the transmission waveform, and the lower side is the reception waveform. The horizontal axis of FIG. 5 is time, and the vertical axis of 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 14 controls the operation of the light source 11 and controls the period of the laser beam and the pulse width. The laser scanning device 10 transmits laser light as a pulse signal.

Let the period P of the pulse signal and the pulse width W. Let the delay amount Δ, which is the time from the transmission of one pulse to the reception of the pulse reflected by the object, and the speed of light C. The delay amount Δ is calculated by “Δ = 2 L / C”. The distance calculation unit 16 calculates the distance from the vehicle 1 to the object 2 by 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.

FIG. 6 is a diagram illustrating a scanning region AR of the laser scanning apparatus 10. The laser scanning device 10 including the light source 11 and the deflection element 12 can scan the scanning region AR separated by a predetermined distance (distance L). The circle in FIG. 6 represents the scanning point SP (corresponding to one pulse in FIG. 5) of the laser beam transmitted by the laser scanning device 10. As shown in FIG. 6, the period for transmitting the laser beam by the laser scanning device 10 is predetermined. One frame corresponding to one scanning area AR is scanned by a predetermined number of scanning points SP. The scanning direction is, for example, the vertical direction (lower side of FIG. 6). That is, a plurality of columns are scanned in order in the vertical direction from right to left. Then, a plurality of frames are sequentially acquired by time division. The main control unit 17 sets the size of the scanning area AR and the scanning direction according to a predetermined operation mode.

[3-2] Operation of Deflection Element 12 Next, the operation of the deflection element 12 will be described. The deflection angle control unit 15 has the first electrodes 25-1 to 25-3 and the second electrodes 26-1 to 26-3 included in the liquid crystal panels 20-1 to 20-3 in order to drive the deflection element 12. A voltage is applied to the third electrode 27-1 to 27-3 and the fourth electrode 28-1 to 28-3.

FIG. 7 is a cross-sectional view illustrating the operation of the deflection element 12 according to the first example. The first example is an operation in which the laser beam is not refracted.

The deflection angle control unit 15 applies 0V to the first electrode 25, the second electrode 26, the third electrode 27, and the fourth electrode 28. Alternatively, the deflection angle control unit 15 applies a predetermined common voltage to the first electrode 25, the second electrode 26, the third electrode 27, and the fourth electrode 28. That is, the voltage applied to the two electrodes facing each other across the liquid crystal layer may be the same.

The deflection element 12 receives a laser beam (infrared laser) from the light source 11. In each of the liquid crystal layers of the liquid crystal panels 20-1 to 20-3, the liquid crystal molecules are oriented substantially in the horizontal direction. Therefore, the refractive index gradient does not occur in the deflection element 12, and the laser light emitted from the deflection element 12 is hardly refracted. The length of the small arrow in FIG. 7 schematically shows the state of the phase of the laser beam in the plurality of partial regions of the deflection element 12.

FIG. 8 is a cross-sectional view illustrating the operation of the deflection element 12 according to the second example. The second example is an operation of refracting the laser beam to the left at an emission angle θ1 (> 0).

The deflection angle control unit 15 applies an effective voltage V1 (> 0) between the first electrode 25 and the third electrode 27 in each of the liquid crystal panels 20-1 to 20-3. The effective voltage V1 is a voltage lower than the voltage at which the liquid crystal molecules are vertically oriented (the threshold voltage of the liquid crystal). The effective voltage V1 is an AC voltage. As a result, the liquid crystal molecules are oriented obliquely between the first electrode 25 and the third electrode 27. By changing the magnitude of the effective voltage V1, the inclination of the liquid crystal molecules can be arbitrarily changed.

Further, the deflection angle control unit 15 applies 0V to the second electrode 26 and the fourth electrode 28. As a result, the liquid crystal molecules are oriented substantially horizontally between the second electrode 26 and the fourth electrode 28.

Here, the first electrodes 25-1 to 25-3 are formed in a stepped shape, and the third electrodes 27-1 to 27-3 facing the first electrodes 25-1 to 25-3 are also formed in a stepped shape. Will be done. Therefore, the phase of the laser beam transmitted through the deflection element 12 is delayed toward the left in FIG. That is, the more the laser beam passes through the liquid crystal layer containing the liquid crystal molecules oriented in the substantially horizontal direction, the more the phase is delayed.

FIG. 8 shows how the phase of the laser beam advances as the arrow indicating the phase becomes longer. In other words, the refractive index gradient is formed in the deflection element 12 so that the refractive index gradually increases from the right to the left in FIG. As a result, the laser light emitted from the deflection element 12 is refracted to the left at the emission angle θ1. The emission angle is an angle of the deflection element 12 with respect to the direction perpendicular to the substrate.

FIG. 9 is a cross-sectional view illustrating the operation of the deflection element 12 according to the third example. The third example is an operation of refracting the laser beam to the left at an emission angle of θ2 (> θ1).

The deflection angle control unit 15 applies an effective voltage V2 (> V1) between the first electrode 25 and the third electrode 27 in each of the liquid crystal panels 20-1 to 20-3. The effective voltage V2 is a voltage capable of vertically aligning the liquid crystal molecules, and is a voltage equal to or higher than the threshold voltage of the liquid crystal. The effective voltage V2 is an AC voltage. As a result, the liquid crystal molecules are oriented substantially vertically between the first electrode 25 and the third electrode 27.

Further, the deflection angle control unit 15 applies 0V to the second electrode 26 and the fourth electrode 28. As a result, the liquid crystal molecules are oriented substantially horizontally between the second electrode 26 and the fourth electrode 28.

The phase of the laser beam transmitted through the deflection element 12 is delayed toward the left in FIG. Further, in FIG. 9, the gradient of the refractive index is larger than that in FIG. As a result, the laser light emitted from the deflection element 12 is refracted to the left at an emission angle of θ2 (> θ1).

FIG. 10 is a cross-sectional view illustrating the operation of the deflection element 12 according to the fourth example. The fourth example is an operation of refracting the laser beam to the right at an emission angle θ1 (> 0).

The deflection angle control unit 15 applies an effective voltage V1 (> 0) between the second electrode 26 and the fourth electrode 28 in each of the liquid crystal panels 20-1 to 20-3. The effective voltage V1 is a voltage lower than the voltage at which the liquid crystal molecules are vertically oriented. As a result, the liquid crystal molecules are oriented obliquely between the second electrode 26 and the fourth electrode 28.

Further, the deflection angle control unit 15 applies 0V to the first electrode 25 and the third electrode 27. As a result, the liquid crystal molecules are oriented substantially horizontally between the first electrode 25 and the third electrode 27.

Here, the second electrodes 26-1 to 26-3 are formed in an inverted step shape, and the fourth electrodes 28-1 to 28-3 facing the second electrodes 26-1 to 26-3 are also formed in an inverted step shape. Is formed in. Therefore, the phase of the laser beam transmitted through the deflection element 12 is delayed toward the right in FIG. In other words, the refractive index gradient is formed on the deflection element 12 so that the refractive index gradually increases from the left to the right in FIG. As a result, the laser light emitted from the deflection element 12 is refracted to the right at the emission angle θ1.

FIG. 11 is a cross-sectional view illustrating the operation of the deflection element 12 according to the fifth example. The fifth example is an operation of refracting the laser beam to the right at an emission angle of θ2 (> θ1).

The deflection angle control unit 15 applies an effective voltage V2 (> V1) between the second electrode 26 and the fourth electrode 28 in each of the liquid crystal panels 20-1 to 20-3. The effective voltage V2 is a voltage capable of vertically aligning the liquid crystal molecules, and is a voltage equal to or higher than the threshold voltage of the liquid crystal. As a result, the liquid crystal molecules are oriented substantially vertically between the second electrode 26 and the fourth electrode 28.

Further, the deflection angle control unit 15 applies 0V to the first electrode 25 and the third electrode 27. As a result, the liquid crystal molecules are oriented substantially horizontally between the first electrode 25 and the third electrode 27.

The phase of the laser beam transmitted through the deflection element 12 is delayed toward the right in FIG. Further, in FIG. 11, the gradient of the refractive index is larger than that in FIG. As a result, the laser light emitted from the deflection element 12 is refracted to the left at an emission angle of θ2 (> θ1).

By changing the effective voltage applied to the liquid crystal panel 20 in the range of 0 V or more and the effective voltage V2 or less, the emission angle is changed in the range of 0 degrees (direction perpendicular to the substrate) or more and the angle θ2 or less. be able to. That is, the deflection element 12 can scan the laser beam at a scanning angle twice the emission angle θ2.

When scanning from the direction perpendicular to the substrate to only one side, for example, the left side, only the first electrode 25-1 to 25-3 and the third electrode 27-1 to 27-3 need to be provided, and the third electrode needs to be provided. The 26-1 to 26-3 and the fourth electrodes 28-1 to 28-3 do not need to be provided. Similarly, when scanning only on the right side with respect to the vertical direction, only the third electrode 26-1 to 26-3 and the fourth electrode 28-1 to 28-3 need to be provided, and the first electrode 25- It is not necessary to particularly provide 1 to 25-3 and the third electrode 27-1 to 27-3.

7 to 11 show a configuration and an operation of scanning the laser beam in one dimension (X direction). When scanning the laser beam in two dimensions (X direction and Y direction), in addition to the first deflection element that scans in the X direction, a plurality of electrodes formed in a stepped shape and an inverted stepped shape along the Y direction are used. Another set of the provided second deflection elements is prepared, and the first deflection element and the second deflection element are laminated. That is, the second deflection element has a configuration in which the first deflection element is rotated by 90 degrees. Then, when refracting the laser light in the X direction, the first deflection element is used, and when refracting the laser light in the Y direction, the second deflection element is used and refracted in the oblique direction with respect to the X direction. In the case of making it, the first refracting element and the second refracting element are used. By using such a deflection element, the laser beam can be scanned two-dimensionally.

[4] Effect As described in detail above, in the present embodiment, the laser scanning apparatus 10 includes a light source 11 that emits laser light and laminated liquid crystal panels 20-1 and 20-2, and a laser from the light source 11. A deflection element 12 that refracts light is provided. The liquid crystal panel 20-1 includes the substrates 21-1, 22-1, the electrodes 25-1, 27-1 provided on the substrates 21-1, 22-1, respectively, and facing each other, and the substrates 21-1, 22-. The liquid crystal layer 23-1 filled in 1 space is included. The liquid crystal panel 20-2 includes electrodes 25-2 and 27-2 provided on the substrates 21-2 and 22-2 and the substrates 21-2 and 22-2, respectively, and facing each other, and substrates 21-2 and 22-2. Includes a liquid crystal layer 23-2 filled between the two. In the first direction of scanning the laser beam, the electrode 25-1 is longer than the electrode 25-2. When refracting the laser beam, the deflection angle control unit 15 applies the same effective voltage to the electrodes 25-1 and 25-2.

Therefore, according to the present embodiment, a gradient of the refractive index can be formed in the deflection element 12. As a result, the laser beam incident on the deflection element 12 can be emitted at a desired emission angle.

Further, by preparing a plurality of effective voltages and applying one of the effective voltages to the plurality of liquid crystal panels at the same time, the laser beam can be emitted at a desired emission angle. As a result, the laser beam can be refracted with simple voltage control.

Further, by stacking an optimum number of liquid crystal panels to form the deflection element 12, the gradient of the refractive index formed in the deflection element 12 can be further increased. This makes it possible to realize a laser scanning device capable of refracting laser light with a large emission angle (refraction angle).

Further, the laser scanning apparatus 10 of the present embodiment has no mechanical components and no mechanical moving parts, so that the reliability can be improved. Further, the laser scanning device 10 can be miniaturized.

The number of the liquid crystal panels 20 to be laminated may be two or more, but from the viewpoint of making the gradient of the refractive index formed in the deflection element 12 smoother, the number of the liquid crystal panels 20 is three. The above is desirable. On the other hand, as the number of liquid crystal panels 20 increases, the thickness of the deflection element 12 increases. Therefore, the number of the liquid crystal panels 20 constituting the deflection element 12 is optimally set according to the required specifications while considering the smoothness of the gradient of the refractive index and the thickness of the deflection element 12.

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

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

The present invention is not limited to the above-described embodiment, and can be variously modified at the implementation stage without departing from the gist thereof. In addition, each embodiment may be carried out in combination as appropriate, and in that case, the combined effect can be obtained. Further, the above-described embodiment includes various inventions, and various inventions can be extracted by a combination selected from a plurality of disclosed constituent requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the problem can be solved and the effect is obtained, the configuration in which the constituent requirements are deleted can be extracted as an invention.

10 ... Laser scanning device, 11 ... Light source, 12 ... Deflection element, 13 ... Light receiving element, 14 ... Pulse timing control unit, 15 ... Deflection angle control unit, 16 ... Distance calculation unit, 17 ... Main control unit, 20 ... Liquid crystal panel , 21 and 22 ... Substrate, 23 ... Liquid crystal layer, 24 ... Sealing material, 25-28 ... Electrode

Claims (8)

A light source that emits laser light and
It includes the first and second liquid crystal panels that are laminated, and includes a deflection element that refracts the laser light from the light source.
The first liquid crystal panel is
1st and 2nd boards,
A first electrode provided on the first substrate and extending in the first direction,
A second electrode provided on the second substrate, facing the first electrode, and having the same size as the first electrode,
Includes a first liquid crystal layer filled between the first and second substrates.
The second liquid crystal panel is
With the 3rd and 4th boards
A third electrode provided on the third substrate and extending in the first direction,
A fourth electrode provided on the fourth substrate, facing the third electrode, and having the same size as the third electrode,
A second liquid crystal layer filled between the third and fourth substrates is included.
The third electrode overlaps with the first electrode in a plan view.
A laser scanning apparatus in which the first electrode is longer than the third electrode in the second direction orthogonal to the first direction. The laser scanning apparatus according to claim 1, wherein the first electrode and the third electrode are formed in a stepped shape. The laser scanning apparatus according to claim 1 or 2, further comprising a control unit for applying a first voltage to the first electrode and the third electrode, respectively. The first liquid crystal panel is
A fifth electrode provided on the first substrate and extending in the first direction,
A sixth electrode provided on the second substrate, facing the fifth electrode, and having the same size as the fifth electrode is further included.
The second liquid crystal panel is
A seventh electrode provided on the third substrate and extending in the first direction,
An eighth electrode provided on the fourth substrate, facing the seventh electrode, and having the same size as the seventh electrode is further included.
The 7th electrode overlaps the 5th electrode in a plan view.
The laser scanning apparatus according to claim 1 or 2, wherein in the second direction, the fifth electrode is shorter than the seventh electrode. The laser scanning apparatus according to claim 4, wherein the fifth electrode and the seventh electrode are formed in an inverted stepped shape. In the first operation, a first voltage is applied to the first electrode and the third electrode, respectively, and a second voltage is applied to the fifth electrode and the seventh electrode, respectively.
A claim that further comprises a control unit that applies the second voltage to the first electrode and the third electrode, respectively, and applies the first voltage to the fifth electrode and the seventh electrode, respectively, in the second operation. The laser scanning apparatus according to 4 or 5. The laser scanning apparatus according to any one of claims 1 to 6, further comprising a light receiving element for detecting the laser light emitted from the deflection element and reflected by the object. The laser scanning apparatus according to any one of claims 1 to 7, wherein each of the first and second liquid crystal panels is configured in a homogeneous mode, a VA (Vertical Alignment) mode, or a TN (Twisted Nematic) mode.

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