JP6123163B2 - Distance measuring device - Google Patents

Description

  The present invention relates to a distance measuring device that measures a distance to an object.

  2. Description of the Related Art Conventionally, a distance measuring device that monitors a visual field region of a predetermined angle (all scanning angles) and measures a distance to an object (object) existing in the visual field region, such as a radar device mounted on a vehicle, is known. . The distance measuring device includes a light projecting unit having an optical scanning mechanism such as a laser light source and a rotating mirror, and a light receiving unit having a condensing lens, a light receiving element, and the like. Laser light emitted from the light source is deflected and projected by an optical scanning mechanism, and the field of view is scanned with the laser light. The laser light reflected by the object existing in the visual field area is condensed by the condenser lens and received by the light receiving element.

  Since the conventional distance measuring device monitors a specific direction such as the front of the vehicle as a visual field region, the total scanning angle is usually less than 180 °. In recent years, with the development of surveillance cameras and objective sensors, distance measuring devices having a wider field of view (for example, all directions) are required. For example, Patent Document 1 discloses a range measurement device that simultaneously detects surrounding objects in a 360 ° field of view along the horizontal direction and measures the distance and angle (azimuth) to the detected surrounding objects.

  The range measuring device described in Patent Document 1 includes a flash laser radar, an image sensor, a mirror element coupled between the image sensor and the laser radar, and a lens. The flash laser radar generates a first laser pulse at a first time to illuminate a 360 ° field of view along the horizontal direction. The range measurement device receives a reflection of the first laser pulse from at least one object in the 360 degree field of view at a second time.

  The mirror element includes a first reflector configured to disperse the reflection of the first laser pulse to at least a portion of the 360 degree field of view, and the return of the first laser pulse from the at least one object into the image sensor. And a second reflector configured to collect the reflection. The lens is configured to collect the return reflection to the image sensor.

  In the above range measuring device, the distance to the object is calculated based on the “first time” when the first laser pulse is generated and the “second time” when the reflection of the first laser pulse is received. Yes. That is, the delay time τ of the reflected light pulse is obtained as the difference between the first time and the second time, and the distance L to the object is calculated from the delay time τ and the speed of light c based on the relationship of τ = 2L / c. ing.

JP 2009-47695 A

  However, in the range measuring device described in Patent Document 1, since the distance to the object is calculated based on the delay time of the reflected light pulse, in order to measure the distance in all directions, the distance to the object and every direction It is necessary to pre-allocate image sensor pixels. In addition, in order to measure the distance in all directions, it is necessary to acquire the delay time of the reflected light pulse for each pixel of the image sensor, and the processing becomes complicated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to simultaneously detect an object in a visual field region including a plurality of directions with a simple configuration without providing a movable part such as a scanning mechanism. Another object of the present invention is to provide a distance measuring device capable of measuring the distance to a given object at a time.

To achieve the above object, an invention according to claim 1, imaging device having a light source, a light projecting optical system for projecting light light emitted from the light source, an imaging surface light image is formed When the reflected light reflected by the object of projecting to and the measurement object with the light receivable configured, position on the imaging surface a predetermined according to the distance to the object based on the principle of triangulation A light receiving optical system that forms an image of the received reflected light on the imaging surface, and a position of the optical image formed on the imaging surface so that an optical image corresponding to the reflected light received on the imaging surface is formed. Distance acquisition means for acquiring a distance to an object to be measured based on the projection optical system, the projection optical system includes a conical transmission surface, and the optical axis coincides with the optical axis of the light source. A cone-shaped transmission surface is disposed toward the light source, and light emitted from the light source is annular light. A conical lens to be shaped, and a first semiconical mirror provided with a reflective surface inside a semiconical side surface, the reflective surface being arranged facing the conical lens, wherein the central axis of the semiconical is the optical axis A first semiconical mirror that reflects a part of the annular light in a first direction along a direction intersecting the optical axis, and a reflective surface outside the side surface of the semiconical shape. A second semi-conical mirror having a surface facing the conical lens, the central axis of the semi-conical being coincident with the optical axis, and being displaced from the first semi-conical mirror in the optical axis direction And a second semi-conical mirror that reflects another part of the annular light in a second direction different from the first direction along a direction intersecting the optical axis. is there.

  According to a second aspect of the present invention, the image pickup device picks up a light image formed on an image pickup surface, and the distance acquisition unit obtains position information of the light image from an image picked up by the image pickup device. And obtaining a distance from a position of a light image formed on the imaging surface to an object to be measured based on a correspondence relationship between a distance to the object and a position on the imaging surface. 1. The distance measuring device according to 1.

According to a third aspect of the present invention, the light projecting optical system is a light shielding member in which a plurality of openings are provided along one circle, and is disposed between the conical lens and the second semi-conical mirror. 3. The light modulation device according to claim 1 , further comprising a light modulation element that modulates a spatial distribution of luminance of the continuous annular light generated by the conical lens so that discontinuous annular light is generated. This is a distance measuring device.

The invention according to claim 4 is an annular lens in which the light receiving optical system includes a toroidal surface and is disposed with the toroidal surface facing outward, and collects reflected light reflected by the object to be measured. A convex mirror having a curved reflecting surface that is axially symmetric with respect to the optical axis of the light source, and the reflecting surface is disposed toward the imaging lens, and the light collected by the annular lens A convex mirror that reflects in the direction of the optical axis, and an imaging lens that is arranged so that the optical axis coincides with the optical axis of the light source, and forms an image of the light reflected by the convex mirror on the imaging surface of the imaging device The distance measuring device according to any one of claims 1 to 3, further comprising:

  Providing a distance measurement device that can simultaneously detect objects in the field of view including multiple orientations and measure the distance to the detected objects at the same time with a simple configuration without providing a movable part such as a scanning mechanism. can do.

It is a figure which shows the structure of the distance measuring device which concerns on 1st Embodiment. (A) is a perspective view which shows the external appearance of a distance measuring device. (B) is a perspective view which shows the internal structure of a distance measuring device. (C) is sectional drawing along the rotational symmetry axis of the distance measuring device. It is sectional drawing along the rotational symmetry axis which shows operation | movement of the distance measuring apparatus shown in FIG. It is a block diagram which shows the electrical structure of the distance measuring device shown in FIG. (A) And (B) is a schematic diagram for demonstrating the principle of the distance measurement by a triangulation. It is a schematic diagram for demonstrating the relationship between the luminescent spot on an image sensor, and a measuring object. (A) And (B) is sectional drawing along the rotational symmetry axis of the distance measuring device which concerns on a modification. It is a schematic diagram for demonstrating the signal processing operation | movement of the distance measuring apparatus shown in FIG. It is a figure which shows the structure of the distance measuring device which concerns on 2nd Embodiment. (A) is sectional drawing along the rotational symmetry axis of the distance measuring device. (B) is a top view of a light modulation element. (A) is a schematic diagram for demonstrating operation | movement of the distance measuring apparatus shown in FIG. (B) is a top view which shows the arrangement | sequence of the bright spot on an image pick-up element. (C) is the elements on larger scale which show the shift | offset | difference from the reference | standard position of a luminescent point. It is sectional drawing along the rotational symmetry axis of the distance measuring device which concerns on the other modification which produces | generates some annular light. (A) is sectional drawing along the rotational symmetry axis of the distance measuring device which concerns on the other modification which has a visual field area narrower than all directions. FIG. 4B is a perspective view illustrating a configuration of a main part of the light projecting optical system. (A)-(C) are perspective views which show the structure of the principal part of the light projection optical system of the distance measuring device which concerns on another modification. (A) is sectional drawing along the rotational symmetry axis of the distance measuring device which concerns on another modification. FIG. 4B is a perspective view illustrating a configuration of a main part of the light projecting optical system. (C) is a perspective view showing a configuration according to a modification of the main part of the light projecting optical system. It is a flowchart which shows the processing routine of "distance acquisition processing."

<First Embodiment>
(Configuration of distance measuring device)
The configuration of the distance measuring apparatus according to the first embodiment will be described.
FIG. 1A is a perspective view showing the appearance of the distance measuring device. FIG. 1B is a perspective view showing the internal structure of the distance measuring device. FIG. 1C is a cross-sectional view along the rotational symmetry axis of the distance measuring device. As shown in FIGS. 1A to 1C, a distance measuring device 10 includes a light source 20 that emits laser light, a light projecting optical system 30 that projects laser light emitted from the light source 20 onto a visual field region, and two An image sensor 40 having an imaging surface constituting a dimensional coordinate system, and a light receiving optical system 50 that receives reflected light from an object in the field of view and forms an image on the imaging surface of the image sensor 40 are provided.

  In the present embodiment, the distance measuring apparatus 10 monitors all horizontal directions (360 ° range) as the visual field region. Accordingly, the light projecting optical system 30 is configured to project the laser light emitted from the light source 20 in all horizontal directions. The light receiving optical system 50 is configured to receive reflected light from an object in all horizontal directions. In the present embodiment, the light receiving optical system 50 is triangulated from an optical image (hereinafter referred to as “bright spot”) obtained by forming the received reflected light on the imaging surface of the imaging device 40. The distance measurement can be performed based on the above principle.

  Further, as the viewing area is set in all directions, each of the light source 20, the light projecting optical system 30, and the light receiving optical system 50 is rotationally symmetric that always overlaps itself even if it is rotated 360 ° around the rotational symmetry axis 12. It has sex. In the present embodiment, the axial direction in which the rotationally symmetric axis 12 extends coincides with the vertical direction orthogonal to the horizontal direction. In the case where the visual field region is not in the horizontal direction but in the oblique lower direction, the axial direction in which the rotationally symmetric axis 12 extends coincides with the vertical direction that intersects the light projecting direction. When monitoring a specific direction in the vertical direction as the visual field region, the axial direction in which the rotationally symmetric axis 12 extends coincides with the horizontal direction orthogonal to the vertical direction.

  Each of the light source 20, the light projecting optical system 30, the image sensor 40, and the light receiving optical system 50 is housed in a cylindrical transparent casing 60. As will be described later, the annular lenses 38 and 58 are attached to the outer peripheral portion of the housing 60. Here, the term “transparent” means that the projected light and the received light are transmitted. Note that the projected light and the received light need not be blocked by the housing 60, and the entire housing 60 does not need to be transparent. Moreover, the housing | casing 60 should just accommodate the light source 20, the light projection optical system 30, etc., and the shape of the housing | casing 60 is not necessarily limited to a cylindrical shape. For example, it may be a rectangular parallelepiped, a cube, or an indefinite shape.

  As the light source 20, a laser light source such as a semiconductor laser can be used. The light source 20 is disposed on the rotationally symmetric axis 12 with the light emission surface facing the light projecting optical system 30 side so that the laser light is emitted to the light projecting optical system 30 side. The light source 20 is supported in the housing 60 by the support member 21. The light source 20 emits laser light in a predetermined direction so that the optical axis of the emitted laser light coincides with the rotational symmetry axis 12. The light source 20 is modulated and driven by a light source driving unit 72 described later, and emits pulse-modulated laser light. Although pulse modulation is not essential, by modulating the light to be projected, it becomes easy to distinguish the reflected light from the object and disturbance light such as sunlight on the light receiving side.

  The light projecting optical system 30 includes a conical lens 32 having a conical transmission surface, a lens 34 for collimating incident light, a convex mirror 36 having a curved reflection surface that is axisymmetric with respect to the rotational symmetry axis 12, and An annular lens 38 having a toroidal surface on the outside is provided. As the conical lens 32, an axicon lens or the like can be used. As the annular lens 38, a toroidal lens or the like can be used. The conical lens 32, the lens 34, the convex mirror 36, and the annular lens 38 are arranged in this order from the light source 20 side along the optical path of the projected light. Each of the conical lens 32, the lens 34, and the convex mirror 36 is supported in the housing 60 by the support members 33, 35, and 37.

  The conical lens 32 is disposed on the light emission side of the light source 20 with the conical transmission surface facing the light source 20 side. The lens 34 is disposed on the light exit side of the conical lens 32. The convex mirror 36 is arranged on the light exit side of the lens 34 with the curved reflecting surface facing the lens 34 side. The annular lens 38 is attached to the outer peripheral portion of the housing 60 with the toroidal surface facing outward. Here, “outside” is a direction away from the rotational symmetry axis 12. In addition, each of the conical lens 32 and the lens 34 is disposed so that the optical axis coincides with the rotational symmetry axis 12.

  As the imaging device 40, an image sensor such as a CCD image sensor or a CMOS image sensor can be used. The imaging element 40 is disposed on the rotationally symmetric axis 12 with the imaging surface facing the light receiving optical system 50 side. The reflected light incident on the light receiving optical system 50 is imaged on the imaging surface of the image sensor 40 by the light receiving optical system 50. The image sensor 40 is supported in the housing 60 by a support member 41. As will be described later, the imaging surface of the imaging device 40 is configured as a two-dimensional coordinate system with the center as the origin.

  On the imaging surface of the imaging element 40, a plurality of light receiving elements (pixels) are two-dimensionally arranged from the center toward the outside. As the light receiving element, a highly sensitive light receiving element is preferable. For example, it is possible to use a light receiving element with higher sensitivity than a normal photodiode, such as an avalanche photodiode (APD) or a single photon detection light receiving element. The imaging surface of the imaging device 40 may have a circular shape or a rectangular shape in plan view. In the present embodiment, description will be made assuming that the imaging surface of the imaging element 40 is rectangular.

  In addition, a gate unit that switches the imaging region may be provided between the imaging element 40 and the light receiving optical system 50. The gate unit switches the imaging area by blocking incident light to an area other than the imaging area. Thereby, unnecessary light such as stray light or disturbance light does not enter the image sensor 40, and noise of the image signal is reduced. For example, when the measurement distance is a short distance, the center area of the imaging surface of the image sensor 40 is used as the imaging area. On the other hand, when the measurement distance is a long distance, the peripheral area of the imaging surface of the imaging element 40 is used as the imaging area. Therefore, the gate unit is operated at a timing according to the measurement distance so that the imaging region is switched to the central region when the measurement distance is short and the imaging region is switched to the peripheral region when the measurement distance is long. May be.

  The light receiving optical system 50 includes an imaging lens 52 that forms an image of incident light, a light shielding member 54 having an opening 54A, a convex mirror 56 having a curved reflecting surface that is axisymmetric with respect to the rotationally symmetric axis 12, and a toroidal outward. An annular lens 58 having a surface is provided. The annular lens 58, the convex mirror 56, the light shielding member 54, and the imaging lens 52 are arranged in this order from the incident side of the reflected light along the optical path of the received light. The light shielding member 54 having the opening 54A may be a diaphragm mechanism that can mechanically change the diameter of the opening 54A.

  The annular lens 58 is attached to the outer periphery of the housing 60 with the toroidal surface facing outward. The convex mirror 56 is disposed on the light exit side of the annular lens 58 with the curved reflecting surface facing the light shielding member 54 side. The light shielding member 54 is disposed on the light reflecting side of the convex mirror 56. The imaging lens 52 is disposed on the light exit side of the light shielding member 54 having the opening 54A. The imaging lens 52 is arranged so that the optical axis coincides with the rotational symmetry axis 12. The light shielding member 54 is disposed so that the rotationally symmetric axis 12 passes through the approximate center of the opening 54A. The annular lens 58 is arranged such that the rotational symmetry axis passing through the center thereof coincides with the rotational symmetry axis 12.

  In other words, each part of the distance measuring device 10 according to the present embodiment is fixedly arranged and does not include a mechanically driven movable part such as a rotating mirror. For this reason, the measurement speed can be improved, the failure of the apparatus can be reduced, the apparatus can be downsized, the cost of the apparatus can be reduced, etc. Compared to the device, it has a number of advantages.

(Operation of distance measuring device)
Next, the operation of the distance measuring device according to the first embodiment will be described.
FIG. 2 is a cross-sectional view along the rotational symmetry axis showing the operation of the distance measuring apparatus shown in FIG. As shown in FIG. 2, the laser light emitted from the light source 20 is applied to the apex of the conical transmission surface of the conical lens 32 and the periphery thereof. The laser light having straightness is incident on the conical lens 32 as parallel light. The conical lens 32 shapes the incident parallel light into an annular light. By shaping into annular light, light utilization efficiency is improved. The annular light generated by the conical lens 32 enters the lens 34. The lens 34 collimates the incident annular light.

The annular parallel light generated by the lens 34 is irradiated onto the curved reflecting surface of the convex mirror 36 and reflected outward along the horizontal direction. The light reflected outside by the convex mirror 36 enters the annular lens 38. Toric lens 38 is collimated light reflected by the convex mirror 36, for projecting a laser beam B _S which is pulse-modulated in all directions in the horizontal direction. By making the light parallel, the spread of the projected laser beam is suppressed and the measurement accuracy is improved.

An object in the visual field region is set as a target object T which is a distance measurement target. The laser beam reflected by the object T (reflected light) B _R is incident on the toric lens 58 from the toroidal surface. The toric lens 58, the reflected light B _R from the object T located in all directions in the horizontal direction is incident. Toric lens 58 condenses the incident reflected light B _R. The light condensed by the annular lens 58 is applied to the curved reflecting surface of the convex mirror 56 and reflected to the light shielding member 54 side. Here, the light irradiated on the convex mirror 56 is reflected in the direction of the rotational symmetry axis 12.

  A part of the light reflected by the convex mirror 56 passes through the opening 54 </ b> A and the remaining part is blocked by the light shielding member 54. Unnecessary light such as stray light is blocked by the light blocking member 54, thereby improving measurement accuracy. The light that has passed through the opening 54 </ b> A enters the imaging lens 52. The imaging lens 52 focuses incident light on the imaging surface of the imaging device 40. Bright spots corresponding to the reflected light from the object T are formed on the imaging surface of the imaging element 40. The image sensor 40 detects light received by each pixel, performs photoelectric conversion, and outputs a digitized image signal for each pixel. In the following description, it is assumed that the image pickup device 40 outputs a digital image signal subjected to A / D conversion processing.

  In the present embodiment, the distance L from the distance measuring device 10 to the object T is obtained from the image of the bright spot S imaged by the image sensor 40 based on the principle of triangulation. The principle of distance measurement by triangulation will be described later. The imaging surface of the imaging device 40 is configured as a two-dimensional coordinate system with the center C as the origin (see FIGS. 5 and 7). The distance r from the origin to the bright spot S is associated in advance with the distance L to the object T based on the principle of triangulation. Further, the angle θ when the position of the bright spot S is expressed in polar coordinates (r, θ) is also associated with the azimuth angle α of the object T in advance.

  In other words, the light receiving optical system 50 displays the bright spot S represented by the polar coordinates (r, θ) determined in advance corresponding to the distance L to the object T and the azimuth angle α on the imaging surface of the imaging device 40. It is designed to form an image. Furthermore, the light receiving optical system 50 uses the position information (distance L, azimuth angle α) of the object T in the field of view as the position information of the bright spot S on the imaging surface so that the principle of triangulation can be applied. (Distance r, angle θ). Therefore, the distance L to the target T and the azimuth angle α can be acquired from the polar coordinates (r, θ) of the bright spot S on the image captured by the image sensor 40.

(Electrical configuration of distance measuring device)
Next, the electrical configuration of the distance measuring apparatus according to the first embodiment will be described.
FIG. 3 is a block diagram showing an electrical configuration of the distance measuring apparatus shown in FIG. As shown in FIG. 3, the distance measuring apparatus 10 includes a control unit 70, a light source driving unit 72 that drives the light source 20, a display unit 74 that displays measurement results, and an operation input unit 76 that operates the apparatus. . The display unit 74 includes a display device such as a display. The operation input unit 76 includes a touch panel, operation buttons, and the like.

  The control unit 70 is configured as a computer that controls the entire apparatus and performs various calculations. That is, the control unit 70 includes a CPU (Central Processing Unit) 70A, a ROM (Read Only Memory) 70B, a RAM (Random Access Memory) 70C, a non-volatile memory 70D, and an input / output interface (I / O) 70E. It has. Each of the CPU 70A, ROM 70B, RAM 70C, nonvolatile memory 70D, and I / O 70E is connected via a bus 70F.

  Each unit of the light source driving unit 72, the display unit 74, and the operation input unit 76 is connected to the I / O 70E of the control unit 70. The image sensor 40 is also connected to the I / O 70E of the control unit 70. When an analog signal is output from the image sensor 40, it is connected to the I / O 70E of the control unit 70 via an A / D converter. Further, an amplifier that amplifies an analog signal may be inserted between the image sensor 40 and the A / D converter.

  The control unit 70 controls each unit of the light source driving unit 72, the display unit 74, and the operation input unit 76, and performs various calculations. For example, the control signal is input to the light source driving unit 72 so that the pulse-modulated laser light is emitted from the light source 20. The light source driving unit 72 performs pulse modulation driving of the light source 20 based on the input control signal. In addition, an image signal is input from the image sensor 40 and an instruction signal is input from the operation input unit 76 to the control unit 70.

  The CPU 70A of the control unit 70 reads the program stored from the ROM 70B and loads it into the RAM 70C. The CPU 70A uses the RAM 70C as a work area to execute a program loaded on the RAM 70C. In the present embodiment, a control program for executing a “distance acquisition process” for acquiring the distance L to the object T is stored in advance in the ROM 70B. The control program is read from the ROM 70B and executed by the CPU 70A.

  In the present embodiment, the correspondence between the distance r from the origin on the image sensor 40 and the distance L to the object T, the angle θ on the image sensor 40, and the azimuth angle α of the object T Are previously stored in the ROM 70B as a table or graph. Instead of storing the correspondence between the distance r and the distance L, a relational expression for deriving the distance L from the distance r may be stored in advance. When the relational expression is stored, every time the “distance acquisition process” is executed, a calculation is performed based on the stored relational expression, and the distance L is derived from the distance r. Similarly, the azimuth angle α may be derived from the angle θ based on the relational expression.

(Distance measurement principle by triangulation)
Next, the principle of distance measurement by triangulation will be described.
4A and 4B are schematic diagrams for explaining the principle of distance measurement by triangulation. The principle of triangulation is that if the length and angle of a part of the triangle are obtained using the theorem, sine theorem, cosine theorem, etc. The principle is that all side lengths and angles of a triangle can be obtained. As an example, when the length of one side of the triangle and the angles of both ends of the one side are acquired or set, the length of the other two sides and the other one angle are obtained.

  As shown in FIG. 4A, it is assumed that laser light is projected from the distance measuring device 10 in a predetermined direction in a visual field area that extends in the horizontal direction. Laser light is emitted from the light source 20 so that the optical axis coincides with the rotational symmetry axis 12 (that is, in the vertical direction). The laser light emitted in the vertical direction is reflected outward along the horizontal direction by the convex mirror 36 of the light projecting optical system 30. Here, the position where the laser beam is reflected by the convex mirror 36 is referred to as a “projection point F”.

In a predetermined direction of the visual field area, there are three objects T, a standard point A, a standard point B, and a standard point C. The point A, the point B, and the point C are arranged in this order from the side close to the distance measuring device 10. For example, the reflected light reflected by the object T at the mark A is collected by the annular lens 58 of the light receiving optical system 50 and reflected by the convex mirror 56 and taken in. The imaging surface of the imaging device 40, the bright spot S _A corresponding to the position A is imaged. Similarly, the bright spot S _B corresponding to the benchmark _B is imaged, and the bright spot SC corresponding to the benchmark _C is imaged.

In FIG. 4 (B), the arrangement relationship shown in FIG. 4 (A) is simplified, assuming that the position where the reflected light is received by the light receiving optical system 50 is on the rotational symmetry axis 12. That is, it is assumed that an observation surface for detecting the position where the reflected light is received exists on the rotational symmetry axis 12. Here, the position where the reflected light is received is referred to as “light receiving point P”. Gauge A, gauge B, and according to each of the reference points C, and on the axis of rotational symmetry 12 receiving point _{P A,} the light receiving point _{P B,} and receiving point _{P C} is present.

  In FIG. 4 (A) and FIG. 4 (B), “far” and “near” are the far and near distances from the distance measuring device 10 to the benchmark. The longer the distance L from the distance measuring device 10 to the gauge point, the shorter the distance from the “light projection point F” of the corresponding light receiving point P.

For example, when the object T exists in the nearest gage A from the distance measuring device 10, projecting point F, the gauge A, right triangle FAP _A whose vertices receiving point P _A is formed. Projecting point F and immovable triangular point, a line segment with both ends and projecting point F and the light receiving point P _A to baseline. The angle ∠AFP _A is a right angle (90 °). Further, the angle ∠AP _A F is an additional angle of the incident angle of the reflected light with respect to the observation surface. Therefore, when the base line length L _FP and the angle ∠AP _A F (or incident angle) are acquired or set, the distance L _FA from the projection point F to the target point A based on the principle of triangulation. Is required.

On the contrary, the length L _{FP of the} base line and the angle ＡAP _A F can be set according to the distance L _FA from the projection point F to the target point A. In this embodiment, the light receiving optical system 50, so as to correspond to the light receiving point P _A on the axis of rotational symmetry 12, the bright spot S _A is formed on the imaging surface of the imaging device 40. At this time, by applying the same principle as the triangulation as described above, according to the distance L _FA from the transmission point F to the gauge A, the distance r _A from the origin of the bright spot S _A is set.

  As described above, the light receiving optical system 50 of the present embodiment is designed to be able to perform distance measurement based on the principle of triangulation. An optical system to which the principle of triangulation can be applied is designed based on the following design guidelines (1) and (2), for example. (1) The base line of triangulation is made coincident with or parallel to the rotational symmetry axis of the imaging optical system. (2) It has a folding optical system that projects a light receiving point on the base line onto a line perpendicular to the base line.

  According to the above (1) and (2), if there is no folding optical system, a light receiving point that is linearly imaged on the base line is imaged on a line perpendicular to the base line, and the principle of triangulation can be applied. Become. The imaging surface of the imaging device 40 is disposed on a surface including a line perpendicular to a plurality of base lines. By arranging the imaging surfaces in this manner, distance measurement in each direction (for example, 360 °) can be simultaneously performed on one imaging surface.

  For example, in the light receiving optical system 50 shown in FIG. 1, the annular lens 58 is arranged so that the rotational symmetry axis passing through the center coincides with the rotational symmetry axis 12, and creates a condition that allows an image to be formed on a line parallel to the base line. . Further, the convex mirror 56 folds the light emitted from the annular lens 58 in a direction perpendicular to the base line. Then, the imaging lens 52 images the light receiving point on the imaging surface of the imaging device 40 arranged perpendicular to the base line. By configuring the light receiving optical system 50 by combining a plurality of optical elements, it is possible to increase the baseline length and improve the accuracy of triangulation.

(Relationship between bright spot on image sensor and measurement object)
Next, the relationship between the bright spot on the image sensor and the measurement object will be described.
FIG. 5 is a schematic diagram for explaining the relationship between the bright spot on the image sensor and the measurement object. In the description of the principle of triangulation, the case where laser light is projected in a predetermined direction has been described with reference to FIG. 4, but in this embodiment, laser light is projected in all horizontal directions.

  As shown in FIG. 5, when the visual field region extending in the horizontal direction from the distance measuring device 10 is a two-dimensional plane, the objects T existing in all directions are detected simultaneously. In this example, a target T located at a target A, a target B, and a target C located in different directions is detected. In addition, the point close | similar to the distance measuring apparatus 10 in the order of the point A, the point B, and the point C is the same as the example shown in FIG.

  As shown in FIG. 5, the two-dimensional coordinate system on the imaging surface 42 of the imaging element 40 corresponds to the two-dimensional plane of the visual field region of the distance measuring device 10. As described above, the position information (distance L, azimuth angle α) of the object T in the visual field region of the distance measuring device 10 is converted into position information (distance r, angle θ) in the two-dimensional coordinate system of the image sensor 40. On the image pickup surface 42 of the image pickup device 40, a bright spot S corresponding to the object T in the visual field region is imaged. In this embodiment, an example will be described in which the distance r on the image sensor 40 increases as the distance L to the object T increases. However, the distance L on the image sensor 40 increases as the distance L to the object T increases. The distance r may be shortened.

In this example, the gauge is in visual field A, gauge B, and corresponding to each of the target point C, the bright spot S _A, bright spot S _B, bright spots S _C is imaged on the imaging surface 42 ing. Bright spot S _A corresponding to the gauge A close to the distance measuring device 10 is focused at a position closer to the origin. On the other hand, the bright spot S _C corresponding from the distance measuring device 10 to the distant target point C is imaged from the origin position far. In addition, the point A is in the south-southwest direction with respect to the distance measuring device 10. Bright spot S _A corresponding to the target point A, based on the north arrow of the two-dimensional coordinate system on an imaging surface 42, is in the south-southwest orientation with respect to the origin.

  The image sensor 40 captures all the bright spots S imaged on the imaging surface 42 and acquires position information (distance r, angle θ) of the bright spots S on the captured image. The acquired position information (distance r, angle θ) is reconverted into position information (distance L, azimuth angle α) in the visual field area based on the correspondence stored in advance. Therefore, according to the distance measuring apparatus 10 according to the present embodiment, it is possible to measure the distances to all the objects T in all the horizontal directions (viewing area) at a time. The “distance acquisition process” executed by the control unit 70 will be described later.

  Note that the visual field region of the distance measuring device 10 may be limited by the characteristics of the optical elements constituting the light receiving optical system 50. For example, the measurable distance range is limited by the numerical aperture NA of the annular lens 58. The annular lens 58 can collect only light incident at an angle within a predetermined range according to the numerical aperture NA. For example, reflected light from an object existing at a short distance is kicked by the annular lens 58 because the incident angle is too large and cannot be received by the light receiving optical system 50. For this reason, the distance below the predetermined distance from the distance measuring device 10 is a blind spot where the distance to the object cannot be measured.

(Signal processing operation of the control unit)
Next, “distance acquisition processing” executed by the distance measuring apparatus will be described. FIG. 7 is a schematic diagram for explaining the signal processing operation of the distance measuring apparatus shown in FIG. In FIG. 7, the lower limit value r _min of the distance r from the origin (center C) and the upper limit value r _{max of the} distance r are shown by dotted lines in accordance with the measurable distance L range. FIG. 14 is a flowchart showing a processing routine of distance acquisition processing. The distance acquisition process is executed by the CPU 70A of the control unit 70. The distance acquisition process is started when the operation input unit 76 is operated by the user and a distance measurement instruction is received.

  First, in step 100, the light source driving unit 72 is instructed to turn on the light source 20 and perform pulse modulation driving. The light source 20 emits pulse-modulated laser light. The emitted laser light is projected in all directions along the horizontal direction by the light projecting optical system 30.

  Next, in step 102, an image signal is acquired from the image sensor 40 at a light reception timing preset according to the light projection timing and the measurement distance. In the present embodiment, reflected light from the object T in all horizontal directions is received by the light receiving optical system 50. A bright spot S corresponding to the object T is imaged on the imaging surface 42 of the imaging element 40. The image sensor 40 captures an image of the bright spot S and outputs an image signal to the control unit 70.

  Note that a reference image signal at the time of non-light projection (a state in which reflected light is not received) may be acquired in advance from the image sensor 40 and stored as correction information. By performing correction by subtracting the reference image signal from the image signal acquired in step 102, the signal-to-noise ratio (S / N) of the image signal can be improved.

  Next, in step 104, it is determined whether or not the luminance (light intensity) of the detected bright spot S is equal to or higher than a preset threshold value based on the image signal. If the determination in step 104 is affirmative, the light intensity of the bright spot S is high, so that it is recognized as a bright spot by the reflected light from the object T and added to the processing target, and the process proceeds to the next step 106. On the other hand, in the case of negative determination in step 104, since the light intensity of the bright spot S is low, it is recognized that it is not a bright spot due to the reflected light from the object T (noise due to stray light etc.) and is excluded from the processing target. Exit.

  Next, in step 106, it is determined whether or not determination has been made for all detected bright spots S. If the determination in step 106 is affirmative, the process proceeds to the next step 108. On the other hand, if a negative determination is made in step 106, the process returns to step 104 to determine whether the light intensity of the other bright spot S is equal to or higher than a preset threshold value.

For example, in the example illustrated in FIG. 7, four bright spots S ₁ , bright spots S ₂ , bright spots S ₃ , and bright spots S ₄ are imaged on the imaging surface 42 of the image sensor 40. Since the light intensity of the bright spot S ₁ , the bright spot S ₂ , and the bright spot S ₃ is equal to or higher than the threshold value, the bright spot is recognized as a bright spot by the reflected light from the object T and added to the processing target. Here, the objects corresponding to each of the bright spot S ₁ , the bright spot S ₂ , and the bright spot S ₃ are distinguished as the target object T ₁ , the target object T ₂ , and the target object T ₃ . On the other hand, the light intensity of the bright points S ₄ because less than the threshold value, is excluded from the processing target.

Next, in step 108, position information (distance r _{1 to} r ₃ , angles θ _{1 to} θ ₃ ) of the bright spots S ₁ , bright spots S ₂ , and bright spots S ₃ to be processed is acquired. Each of the bright spot S ₁ , the bright spot S ₂ , and the bright spot S ₃ corresponds to the distance r ₁ and the angle θ ₁ , the distance r ₂ and the angle θ ₂ , the distance r ₃ and the angle θ ₃ .

Next, in step 110, the distance r ₁ , the distance r ₂ , and the distance r ₃ are referred to by referring to a table showing the correspondence relationship between the distance r from the origin on the image sensor 40 and the distance L to the object T. the distance _{L 1} corresponding to each, the distance _{L 2,} to obtain the distance _{L 3.} Next, in step 112, referring to a table showing the correspondence relationship between the angle θ on the image sensor 40 and the azimuth angle α of the target T, the azimuth corresponding to the angle θ ₁ , the angle θ ₂ , and the angle θ _3. The angle α ₁ , the azimuth angle α ₂ , and the azimuth angle α ₃ are acquired.

Next, in step 114, the display unit 74 is instructed to display the measurement result, and the routine is terminated. The display unit 74 displays a distance L ₁ and an azimuth angle α ₁ , a distance L ₂ and an azimuth angle α ₂ , a distance L ₂ and an azimuth angle α ₂ for each of the target object T ₁ , the target object T ₂ , and the target object T _3. Is displayed.

(Modification of optical system)
Here, a modification of the optical system in the distance measuring apparatus will be described.
6A and 6B are cross-sectional views along the rotational symmetry axis of the distance measuring device according to the modification. A distance measuring apparatus 10A shown in FIG. 6A replaces the convex mirror 36 of the light projecting optical system 30 with a reflecting surface (hereinafter referred to as a conical shape) having the same shape as the side surface of a cone that is axisymmetric with respect to the rotationally symmetric axis 12. The configuration is the same as that of the distance measuring device 10 shown in FIG. 1 except that a conical mirror 80 having a reflective surface is provided, and the same components are denoted by the same reference numerals and description thereof is omitted. The conical mirror 80 is one type of convex mirror having a curved reflecting surface that is axisymmetric with respect to the rotationally symmetric axis 12.

  The conical mirror 80 is disposed on the light exit side of the lens 34 with the conical reflection surface facing the lens 34 side. The conical mirror 80 is supported in the housing 60 by a support member 81. When the annular parallel light transmitted through the lens 34 is reflected to the outside by the conical mirror 80, the annular lens 58 can be omitted because the angle of spread of the reflected light is narrow.

  A distance measuring device 10B shown in FIG. 6B is the distance measuring device shown in FIG. 1 except that a conical mirror 85 having a conical reflecting surface is arranged instead of the convex mirror 56 of the light receiving optical system 50. Since the configuration is the same as 10, the same components are denoted by the same reference numerals and the description thereof is omitted. Similar to the example shown in FIG. 6A, a conical mirror 80 having a conical reflecting surface may be disposed instead of the convex mirror 36 of the light projecting optical system 30.

  The conical mirror 85 is disposed on the light exit side of the annular lens 58 with the conical reflection surface facing the light shielding member 54 side. The conical mirror 85 is supported in the housing 60 by a support member 83. When the light collected by the annular lens 58 is reflected by the conical mirror 85, the bright spot S can be imaged with high precision because the angle of spread of the reflected light is narrow. Therefore, the measurement accuracy of the distance L to the target T is improved.

  In addition, although the example which changes a one part optical element was demonstrated above, each of the light projection optical system 30 and the light reception optical system 50 should just exhibit the above-mentioned predetermined | prescribed function, and the structure of each optical system illustrated It is not limited to things. For example, in the light projecting optical system 30, the conical lens 32, the lens 34, and the annular lens 38 may be omitted. The conical lens 32 may be replaced with another optical element having a function of shaping parallel light into annular light, such as a truncated cone lens or a pair of conical lenses. In the light receiving optical system 50, the light shielding member 54 having the opening 54A may be omitted.

<Second Embodiment>
(Configuration of distance measuring device)
The configuration of the distance measuring device according to the second embodiment will be described.
FIG. 8A is a cross-sectional view along the rotational symmetry axis of the distance measuring device. FIG. 8B is a plan view of the light modulation element. The distance measuring device 10C according to the second embodiment is related to the first embodiment except that a light modulation element 82 that generates a spatial distribution of luminance is arranged between the lens 34 and the convex mirror 36. Since it is the same structure as the distance measuring apparatus 10, the same code | symbol is attached | subjected to the same component and description is abbreviate | omitted.

  The light modulation element 82 is a light shielding member having a plurality of openings 84 that transmit light. The plurality of openings 84 are regularly arranged so as to be arranged in a radial pattern. In this example, there are a plurality of (three in this example) concentric circles centered on the optical axis, and the plurality of openings 84 are arranged along each concentric circle. For each concentric circle, the same number (16 in this example) of openings 84 are arranged at substantially equal intervals.

  The light modulation element 82 is irradiated with annular parallel light transmitted through the lens 34. An irradiation region 86 (shaded region) irradiated with annular parallel light can be set on the surface of the light modulation element 82 facing the lens 34. In the present embodiment, a plurality of openings 84 are provided in the irradiation region 86. Part of the light irradiated to the irradiation region 86 of the light modulation element 82 passes through the plurality of openings 84. On the other hand, the remainder of the light irradiated to the irradiation area 86 of the light modulation element 82 is blocked by the light blocking member.

  As a result, the incident light is intensity-modulated by the light modulation element 82, and parallel light having a spatial distribution of luminance is generated. That is, when the light modulated by the light modulation element 82 is viewed in a cross section orthogonal to the optical axis, the luminance is high in the region corresponding to the plurality of openings 84 and is low in the region corresponding to the light shielding member.

  In the example of the light modulation element 82 shown in FIG. 8B, a plurality (three in this example) of discontinuous annular light with the optical axis as the center is formed. Here, the discontinuous annular light means annular light in which high luminance portions and low luminance portions are alternately arranged along concentric circles. In this embodiment, discontinuous annular light is generated, but continuous annular light may be generated. Here, continuous annular light is normal annular light in which high-luminance portions are continuously arranged along concentric circles.

(Operation of distance measuring device)
Next, the operation of the distance measuring device according to the second embodiment will be described.
FIG. 9A is a schematic diagram for explaining the operation of the distance measuring apparatus shown in FIG. FIG. 9B is a plan view showing the arrangement of bright spots on the image sensor. FIG. 9C is a partially enlarged view showing the deviation of the bright spot from the reference position.

As shown in FIG. 9A, in the distance measuring device 10C, a plurality of concentric discontinuous annular lights generated by the light modulation element 82 are irradiated to different positions on the curved reflecting surface of the convex mirror 36. Then, it is reflected outward along the horizontal direction from a different position in the vertical direction. The light reflected outside by the convex mirror 36 enters the annular lens 38. The annular lens 38 converts the light reflected by the convex mirror 36 into parallel light, and a plurality of (three types in this example) laser light B _S1 and laser light pulse-modulated in a plurality of specified horizontal directions. B _S2 and laser beam B _S3 are projected. Since a plurality of orientations in the horizontal direction are regularly arranged, the laser beam B _S to be projected can be said that the lattice-like light.

A plurality of concentric discontinuous annular lights are reflected at a position closer to the rotational symmetry axis of the convex mirror 36 and reflected outward from a lower position in the vertical direction, as the concentric annular light closer to the optical axis. Therefore, according to the three types of laser light B _S1 , laser light B _S2 , and laser light B _S3 , it is possible to monitor a plurality of specified horizontal directions having different vertical positions (heights) as a visual field region. it can. The laser beam B _S1 , the laser beam B _S2, and the laser beam B _S3 are projected to a higher position in the vertical direction in the order described.

In the present embodiment, three types of laser light B _S1 , laser light B _S2 , and laser light B _S3 are projected onto the visual field regions having different heights, and reflected by the object T in each visual field region. Laser light B _R1 , laser light B _R2 , and laser light B _R3 are received. Each of the laser beam B _R1 , the laser beam B _R2 , and the laser beam B _R3 is reflected light corresponding to each of the laser beam B _S1 , the laser beam B _S2 , and the laser beam B _S3 . That is, distance measurement is performed in a plurality of paths.

As shown in FIG. 9B, in the present embodiment, a bright spot S is formed on a concentric circle RS corresponding to the height by the laser beam B _R1 , the laser beam B _R2 , and the laser beam B _R3 . The innermost concentric circle RS ₁ corresponds to the laser beam B _S1 that monitors the highest position. When the object T is irradiated with the laser beam B _S1 , the reflected light (laser beam B _R1 ) from the object T forms an image on the concentric circle RS ₁ . Similarly, the laser beam _{B R2} is imaged on a concentric circle RS _2, the laser beam _{B R3} is imaged onto a concentric RS _3.

When the object T has irregularities, the distance L to the concave portion is increased, and the distance to the convex portion is shortened. In the example shown in FIG. 9A, the laser beam B _S1 is irradiated to the mark A in the recess, and the laser beam _BR1 is reflected from the mark A. Further, the laser beam B _S2 is applied to the mark B on the convex portion, and the laser beam _BR2 is reflected from the mark B. Further, the laser beam B _S3 is applied to the mark C in the recess, and the laser beam _BR3 is reflected from the mark C.

As shown in FIG. 9C, the bright spot S formed on the concentric circle RS when the object T is not uneven is defined as “reference bright spot S ₀ (indicated by □)”. When the target T has irregularities, the distance L to the concave portion of the target T is longer than when the target T has no irregularities, and the bright spot based on the reflected light from the gauge point in the concave portion S _r (indicated by ■) is formed outside the bright spot S ₀ . On the other hand, the distance L to the convex portion of the object T is shortened, and the bright point S _r (indicated by ■) based on the reflected light from the gauge point existing on the convex portion is formed inside the bright point S _0. .

As shown in FIG. 9B, when viewed in one azimuth where the object T exists, the bright spot S _r (■) due to the reflected light from the gauge points A and C is the bright spot S ₀ (□). It is formed on the outer side. Further, the bright spot S _r (■) due to the reflected light from the benchmark B is formed inside the bright spot S ₀ (□). In other words, the shift directions from the bright point S ₀ of the bright point S _r, seen or gauge is in or protrusions located in the recess. Further, the amount of deviation from the bright spot S _0, it is understood the distance L to the target point. That is, by acquiring the distance L to the target T for a plurality of heights, information regarding the surface shape of the target T can be acquired. In this case, information at different positions in the vertical direction, that is, information in the height direction is acquired.

(Modification of light modulation element)
In the above, the light modulation element 82 shown in FIG. 8B has been exemplified. However, it is only necessary to generate modulated light having a spatial distribution (pattern) of luminance in accordance with the height and direction of a desired visual field. The structure of the element 82 is not limited to this. A random pattern may be given by the light modulation element 82. For example, the incident light may be intensity-modulated using a mesh (mesh), a diffusion plate, or the like as the light modulation element 82. When a random pattern is given, a deviation amount is acquired from the reference position by obtaining a correlation with the reference image by Fourier transform.

(Other variations that generate multiple annular lights)
In addition, although the example which produces | generates several cyclic | annular light with a light modulation element was demonstrated above, you may produce | generate several annular lights with a multistage conical lens. FIG. 10 is a cross-sectional view along a rotational symmetry axis of a distance measuring device according to another modification that generates a plurality of annular lights. The distance measuring device 10D shown in FIG. 10 is different from the projection optical system 30 in that a conical mirror 80 is arranged instead of the convex mirror 36 and a multistage conical lens 90 is arranged instead of the conical lens 32. Since the configuration is the same as the distance measuring device 10 shown in FIG.

  The multistage conical lens 90 has a conical transmission surface having a plurality of gradients. The multistage conical lens 90 is arranged on the light emission side of the light source 20 with the conical transmission surface facing the light source 20 side. The multistage conical lens 90 is arranged so that the optical axis and the rotational symmetry axis 12 coincide. The multistage conical lens 90 is supported in the housing 60 by a support member 91.

  The laser light emitted from the light source 20 is applied to the apex of the conical transmission surface of the multistage conical lens 90 and its periphery. The multistage conical lens 90 shapes incident parallel light into a plurality of annular lights by a conical transmission surface having a plurality of gradients. In the illustrated example, the transmission surface of the multistage conical lens 90 has two kinds of gradients, and two concentric annular lights are generated. The plurality of annular lights generated by the multistage conical lens 90 are converted into parallel light by the lens 34 and irradiated onto the conical mirror 80.

A plurality of concentric annular lights are irradiated to different positions on the conical reflecting surface of the conical mirror 80, and are reflected outward from different positions (heights) in the vertical direction along the horizontal direction. Each light reflected by vertically different heights is projected light as a laser beam B _S of the plurality which are pulse-modulated in all directions in the horizontal direction according to the height in the vertical direction (two in this example) The A plurality of laser beams B _S, in the vertical direction at different positions (heights) can be monitored in all directions in the horizontal direction as a viewing area.

In the above, an example in which a plurality of annular lights are generated by a multistage conical lens has been described. However, when a plurality of annular lights are irradiated by forming a convex mirror or a conical mirror constituting a light projecting optical system in multiple stages. Similarly, it is possible to project a plurality of laser beams B _S from the vertical direction different positions and. For example, in the example shown in FIG. 6A, instead of the conical mirror 80, a multistage conical mirror having a conical reflecting surface in which a plurality of concentric reflecting regions with respect to the optical axis are arranged may be used. . Note that a non-reflective region that does not reflect light is formed between two adjacent reflective regions. Here, the non-reflective region is a region that absorbs and scatters incident light.

<Other variations>
In addition, although the example which monitors all the azimuth | directions of a horizontal direction as a visual field area | region was demonstrated above, a visual field area | region is not necessarily limited to all the azimuth | directions of a horizontal direction. A plurality of orientations or some orientations may be used as the viewing area. FIG. 11A is a cross-sectional view along a rotationally symmetric axis of a distance measuring device according to another modification having a visual field region narrower than all directions. FIG. 11B is a perspective view showing the configuration of the main part of the light projecting optical system.

  A distance measuring device 10E shown in FIG. 11A is the same as that shown in FIG. 1 except that two semiconical mirrors 92 and 94 having semiconical reflecting surfaces are arranged instead of the convex mirror 36 of the light projecting optical system 30. Since the configuration is the same as the distance measuring device 10 shown in FIG.

  As shown in FIG. 11B, the semi-conical mirror 92 has a semi-conical reflecting surface formed inside. The semiconical mirror 92 is disposed on the light exit side of the lens 34 with the semiconical reflecting surface facing the lens 34 side. In addition, the semi-conical mirror 94 has a semi-conical reflecting surface formed on the outside. The semiconical mirror 94 is disposed on the light exit side of the lens 34 with the semiconical reflecting surface facing the lens 34 side.

  Although annular parallel light is irradiated from the lens 34, the half cone mirror 92 and the half cone mirror 94 are arranged so as to be shifted in the horizontal direction so that different light is emitted from the lens 34. Further, the half-cone mirror 92 and the half-cone mirror 94 are arranged so as to be displaced in the vertical direction. The semiconical mirror 92 is disposed further from the lens 34 with respect to the semiconical mirror 94. Each of the semi-conical mirrors 92 and 94 is supported in the housing 60 by a support member (not shown).

As described above, a part of the annular parallel light generated by the lens 34 is irradiated on the semiconical reflection surface of the semiconical mirror 92 and reflected outward along the horizontal direction. The light reflected to the outside by the semiconical mirror 92 is projected as laser light B _S1 pulse-modulated in the first direction along the horizontal direction. Similarly, the other part of the annular parallel light generated by the lens 34 is irradiated onto the semiconical reflecting surface of the semiconical mirror 94 and reflected outward along the horizontal direction. The light reflected to the outside by the semi-conical mirror 94 is projected as a laser beam B _S2 pulse-modulated in the second direction along the horizontal direction.

In the above example, the half-cone mirror 92 is disposed above the half-cone mirror 94 in the vertical direction. Accordingly, the laser beam B _S1 is projected from a position above the laser beam B _{S2 in the} vertical direction. The laser beam B _S1 and the laser beam B _S2 can monitor a specific horizontal direction (narrower than all directions) as a visual field region at different vertical positions (heights).

The first orientation and the second orientation may be different orientations or the same orientation. Further, each of the first orientation and the second orientation may be narrower than the entire orientation, and is not limited to one position. For example, half of the annular parallel light is irradiated onto the half cone mirror 92 and the other half of the annular parallel light is irradiated onto the half cone mirror 94, whereby each of the laser beam B _S1 and the laser beam B _S2 is horizontal. A range of 180 ° in the direction can be monitored as a visual field region. The laser beam B _S1 and the laser beam B _S2 may have different viewing areas.

  12A to 12C are perspective views showing a configuration of a main part of a light projecting optical system of a distance measuring apparatus according to another modification. In the example shown in FIG. 12A, the distance measuring device 10E shown in FIGS. 11A and 11B is the same as that shown in FIGS. Since it is the same structure, the same code | symbol is attached | subjected to the same component and description is abbreviate | omitted.

  As shown in FIG. 12A, the semi-conical semi-transmissive mirror 96 has a semi-conical reflecting surface formed outside. The semi-conical reflection surface is a so-called half mirror, which transmits light irradiated from the inside and reflects light irradiated from the outside. The semi-transmissive mirror 96 is disposed on the light exit side of the lens 34 with the semi-conical reflecting surface facing the lens 34 side. A part of the annular parallel light generated by the lens 34 is irradiated onto the semiconical reflecting surface of the semi-transmissive mirror 96 and reflected outward along the horizontal direction.

  The semi-transmissive mirror 96 is disposed on the light exit side of the semi-conical mirror 92 with the semi-conical transmission surface facing the semi-conical mirror 92 side. Here, the semi-conical transmission surface means an inner surface that is the back side of the reflection surface. Another part of the annular parallel light generated by the lens 34 is reflected by the semi-conical reflecting surface of the semi-conical mirror 92, passes through the transmitting surface of the semi-transmissive mirror 96, and goes outward along the horizontal direction. Is reflected.

In the present embodiment, the semi-conical mirror 92 and the semi-transmissive mirror 96 are light reflected by the reflective surface of the semi-conical mirror 92 and transmitted through the transparent surface of the semi-transmissive mirror 96, and the reflective surface of the semi-transmissive mirror 96. It arrange | positions by the predetermined positional relationship so that the reflected light may be combined. Therefore, the laser beam B _S which is pulse-modulated to a specific orientation along the horizontal direction is projected. Moreover, as two light waves of the phase to be combined are aligned, by adjusting the positional relationship between the semi-conical mirror 92 and the semi-transmissive mirror 96, a high light intensity of the laser beam B _S to be projected it can.

  In the example shown in FIG. 12B, the same as the distance measuring device 10E shown in FIGS. 11A and 11B, except that the light modulation element 98 is inserted between the lens 34 and the half cone mirror 94. Since it is a structure, the same code | symbol is attached | subjected to the same component and description is abbreviate | omitted. As shown in FIG. 12C, the light modulation element 98 is a light shielding member provided with a plurality of openings 99 (outlined portions) that transmit light. The light modulation element 98 generates annular light having a spatial distribution of luminance.

As illustrated in FIG. 12B, by inserting the light modulation element 98, discontinuous annular light is generated as in the second embodiment. Part of the generated discontinuous annular light is reflected to the outside by the semiconical mirror 92, and the laser light B _S1 pulse-modulated in the first direction along the horizontal direction is projected. Another part of the generated discontinuous annular light is reflected on the outside with a half cone mirror 94, the laser beam B _S2 which is pulse-modulated to a second orientation along a horizontal direction is projected The As described above, for each of the laser beam B _S1 and the laser beam B _S2 , a range up to 180 ° in the horizontal direction can be monitored as a visual field region. Further, by using discontinuous annular light, it is possible to monitor a plurality of specified azimuths in the horizontal direction as a visual field region.

  FIG. 13A is a cross-sectional view along a rotational symmetry axis of a distance measuring device according to another modification. FIG. 13B is a perspective view showing the configuration of the main part of the projection optical system. FIG. 13C is a perspective view showing a configuration according to a modification of the main part of the light projecting optical system. In the example shown in FIGS. 13A to 13C, the light source 20 is not disposed on the rotationally symmetric axis 12, and the light projecting optical system 30 is simply configured to include the lens group 22 and the semiconical mirror 100. 1 has the same configuration as that of the distance measuring device 10 shown in FIG. The light shielding member 54 of the light receiving optical system 50 is also omitted.

  As shown in FIGS. 13A and 13B, the light projecting optical system 30 is configured to irradiate the semiconical mirror 100 by shaping the incident light and the semiconical mirror 100 having a semiconical reflecting surface. The lens group 22 is provided. Each of the light source 20, the semiconical mirror 100, and the lens group 22 is supported in the housing 60 by a support member (not shown). The semi-conical mirror 100 has a semi-conical reflecting surface formed outside. The semi-conical mirror 100 is disposed on the light exit side of the lens group 22 with the semi-conical reflecting surface facing the lens group 22 side. The semiconical mirror 100 is arranged so that the rotational symmetry axis of the cone and the rotational symmetry axis 12 coincide with each other.

The laser light emitted from the light source 20 is shaped into light spreading in the horizontal direction by the lens group 22. The light shaped by the lens group 22 is applied to the semi-conical reflecting surface of the semi-conical mirror 100 and reflected outward along the horizontal direction. The light reflected on the outer semi-conical mirror 100 is projected light as the laser beam B _S which is pulse-modulated to a specific orientation along the horizontal direction. As described above, the laser beam B _S can monitor the range of up to 180 ° in the horizontal direction as a viewing area.

As shown in FIG. 13C, a semi-cylindrical mirror 100A having a semi-cylindrical reflecting surface may be used instead of the semi-conical mirror 100. The semi-cylindrical mirror 100A is arranged such that the rotational symmetry axis of the cylinder and the rotational symmetry axis 12 coincide. Also in this case, the light shaped by the lens group 22 is applied to the semi-cylindrical reflecting surface of the semi-cylindrical mirror 100A and reflected outward along the horizontal direction. The light reflected on the outer semi-conical mirror 100 is projected light as the laser beam B _S which is pulse-modulated to a specific orientation along the horizontal direction.

  In addition, the configuration of the distance measuring device described in each of the above embodiments is an example, and it goes without saying that the configuration may be changed without departing from the gist of the present invention. For example, the optical elements constituting each optical system may be replaced with other optical elements having equivalent functions, and the order of the steps in the flowchart may be changed.

DESCRIPTION OF SYMBOLS 10 Distance measuring device 12 Rotation symmetry axis 20 Light source 22 Lens group 30 Projection optical system 32 Conical lens 34 Lens 36 Convex mirror 38 Annular lens 40 Imaging element 42 Imaging surface 50 Light reception optical system 52 Imaging lens 54A Aperture 54 Light shielding member 56 Convex mirror 58 Annular lens 60 Case 70 Control unit 72 Light source drive unit 74 Display unit 76 Operation input unit 80 Cone mirror 82 Light modulation element 84 Aperture 86 Irradiation area 90 Multi-stage cone lens 92 Half cone mirror 94 Half cone mirror 96 Half Transmission mirror 98 Light modulation element 99 Aperture 100 Half cone mirror 100 A Half cylinder mirror

Claims (4)

A light source;
A light projecting optical system for projecting light light emitted from the light source,
An imaging device having an imaging surface on which an optical image is formed;
The reflected light reflected by the object of projecting to and the measurement object with the light receivable configured, receiving a position on the imaging surface a predetermined according to the distance to the object based on the principle of triangulation A light receiving optical system that forms an image of the received reflected light on the imaging surface so that a light image corresponding to the reflected light is formed;
Distance acquisition means for acquiring a distance to an object to be measured based on a position of a light image formed on the imaging surface;
With
The projection optical system is
A cone having a conical transmission surface, the cone-shaped transmission surface facing the light source so that the optical axis coincides with the optical axis of the light source, and shaping the light emitted from the light source into an annular light A lens,
A first semi-conical mirror having a reflective surface inside a semi-conical side surface, the reflective surface being disposed toward the conical lens, wherein a central axis of the semi-conical coincides with the optical axis, and the annular shape A first semiconical mirror that reflects a portion of the light in a first orientation along a direction intersecting the optical axis;
A second semi-conical mirror provided with a reflecting surface outside a semi-conical side surface, the reflecting surface being disposed toward the conical lens, wherein a central axis of the semi-conical coincides with the optical axis and the first The half-conical mirror is arranged with a position shifted in the optical axis direction, and reflects another part of the annular light in a second direction different from the first direction along the direction intersecting the optical axis. A second semi-conical mirror that
Distance measuring device with The imaging device captures an optical image formed on the imaging surface,
The distance acquisition unit acquires position information of the optical image from an image picked up by the image pickup device, and connects to the image pickup surface based on a correspondence relationship between a distance to the object and a position on the image pickup surface. Acquire the distance to the object to be measured corresponding to the position of the imaged light image,
The distance measuring device according to claim 1. The projection optical system is
A light-shielding member having a plurality of openings provided along one circle, and disposed between the conical lens and the second semi-conical mirror so as to generate discontinuous annular light; A light modulation element that modulates the spatial distribution of the luminance of the continuous annular light generated by the lens;
The distance measuring device according to claim 1 or 2. The light receiving optical system is
An annular lens comprising a toroidal surface, arranged with the toroidal surface facing outward, and condensing the reflected light reflected by the object to be measured;
A convex mirror having a curved reflecting surface that is axially symmetric with respect to the optical axis of the light source, the reflecting surface being disposed toward an imaging lens, and the light condensed by the annular lens A convex mirror that reflects in the direction of the axis;
An imaging lens that is arranged so that an optical axis thereof coincides with an optical axis of the light source, and that forms an image of light reflected by the convex mirror on an imaging surface of the imaging device;
including,
The distance measuring device according to any one of claims 1 to 3.