JP7432856B2 - distance measuring device - Google Patents

Description

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

Conventionally, distance measuring devices that measure distances to objects using light have been installed in various devices. A distance measuring device measures the distance to an object based on, for example, the time difference (time of flight) between emitting light and receiving reflected light. In the distance range of the object to be measured, reflected light from the object is focused on the photodetector by the lens.

In Patent Document 1 listed below, an aspherical lens whose focal length gradually and continuously changes and becomes shorter from a central portion toward a peripheral portion is used as a lens for condensing reflected light onto a photodetector. As a result, the peripheral part of the lens becomes a lens part for short-distance detection for detecting detection objects that exist at a short distance, and the part of the lens inside the lens part for short-distance detects objects that exist at a long distance. It becomes a long-distance detection lens part for detecting objects.

Japanese Patent Application Publication No. 2011-149760

When a lens is formed with both a surface corresponding to a long distance and a surface corresponding to a short distance, as in the device described in Patent Document 1, the aperture area of the surface corresponding to a long distance and a surface corresponding to a short distance, respectively, is becomes smaller. In this case, since the amount of reflected light corresponding to each distance decreases, it may become impossible to properly measure the distance to the object.

In view of this problem, an object of the present invention is to provide a distance measuring device that can more appropriately guide reflected light from an object to a photodetector within a distance range of a measurement target.

A main aspect of the present invention relates to a distance measuring device. The distance measuring device according to this aspect includes a projection optical system that projects a laser beam, a condensing lens that condenses the reflected light of the laser beam reflected by an object, and a condensing lens that condenses the reflected light of the laser beam that is reflected by the condensing lens. a photodetector that receives light; a transparent sheet disposed between the condensing lens and the photodetector; an aperture and a periphery of the aperture; and a reflective member having a reflective surface formed in the reflective surface. At least a portion of the reflected light reflected from an object within a distance range shorter than a predetermined distance is reflected by the reflective surface, then reflected by the transparent sheet, and guided to the photodetector.

According to the distance measuring device according to this aspect, at least a part of the reflected light reflected from an object in a distance range closer than a predetermined distance is reflected by the reflective surface of the reflective member and then reflected by the transparent sheet. , guided by a photodetector. This makes it possible to increase the amount of received reflected light from a short distance range. Further, reflected light from a long distance range passes through the aperture of the reflecting member and is focused on the photodetector. Therefore, the amount of received reflected light from a long distance range can also be maintained high. Therefore, according to the distance measuring device according to this aspect, reflected light from an object can be guided to the photodetector more appropriately in the distance range of the measurement target.

As described above, according to the distance measuring device according to the present invention, reflected light from an object can be guided to a photodetector more appropriately in the distance range of a measurement target.

The effects and significance of the present invention will become clearer from the following description of the embodiments. However, the embodiment shown below is merely one example of implementing the present invention, and the present invention is not limited to what is described in the embodiment below.

FIG. 1 is a perspective view showing the configuration of a distance measuring device according to an embodiment. FIG. 2 is a sectional view showing the configuration of the distance measuring device according to the embodiment. FIG. 3A is a top view schematically showing the configuration of the optical unit when viewed in the negative Z-axis direction according to the embodiment. FIG. 3(b) is a bottom view schematically showing the configuration of the optical unit when viewed in the positive direction of the Z-axis according to the embodiment. FIG. 3(c) is a cross-sectional view schematically showing the configuration of the optical unit when the A-A' cross section of the optical unit is viewed in the negative direction of the Y-axis, according to the embodiment. FIGS. 4A and 4B are diagrams schematically showing a luminous flux of reflected light reflected by an object in a distance measurement area, according to a comparative example. FIGS. 5A and 5B are diagrams schematically showing the luminous flux of reflected light reflected by an object in the distance measurement area, according to the embodiment. FIG. 6 is a diagram showing the sizes of each part set in the simulation according to the embodiment and the comparative example. FIGS. 7A and 7B are diagrams showing rays of reflected light when the object plane is at a long distance and a short distance, respectively, according to a simulation of a comparative example. FIGS. 8A and 8B are diagrams showing rays of reflected light when the object plane is at a long distance and a short distance, respectively, according to the simulation of the embodiment. FIG. 9 is a graph showing simulation results according to the embodiment and the comparative example. FIG. 10 is a diagram showing the configuration of the circuit section of the distance measuring device according to the embodiment. FIG. 11A is a bottom view schematically showing the configuration of the optical unit when viewed in the positive direction of the Z-axis, according to a modified example in which the reflecting member has a square tube shape. FIG. 11(b) is a bottom view schematically showing the configuration of the optical unit when viewed in the positive direction of the Z-axis, according to a modified example in which the aperture is square. FIG. 11(c) is a bottom view schematically showing the configuration of the optical unit when viewed in the positive direction of the Z-axis, according to a modified example in which the aperture is elliptical. FIG. 11D is a bottom view schematically showing the configuration of the optical unit when viewed in the positive direction of the Z-axis, according to a modified example in which the aperture has a shape in which semicircles with different diameters are combined. FIG. 12(a) shows the configuration of the optical unit when the AA' cross section of the optical unit is viewed in the Y-axis negative direction, according to a modified example in which the reflective surface is a plane having an angle with respect to the XY plane. It is a sectional view showing typically. FIG. 12(b) is a cross-sectional view schematically showing the configuration of the optical unit when the A-A' cross section of the optical unit is viewed in the Y-axis negative direction, according to a modified example in which the reflective surface is a curved surface. FIGS. 13A and 13B are diagrams schematically showing the luminous flux of reflected light reflected by an object in the distance measurement area, according to a modified example in which the transparent sheet has a predetermined thickness. FIG. 14A is a side perspective view schematically showing the configuration of a distance measuring device according to a modification example in which the light source is arranged on the positive side of the X-axis of the condenser lens. FIGS. 14(b) and 14(c) are perspective views showing the configurations of a condensing lens and a lens barrel, respectively, according to a modification in which the light source is arranged on the positive side of the X-axis of the condensing lens. FIG. 15A is a side perspective view schematically showing the configuration of a distance measuring device according to a modification example in which the light source and the collimator lens are arranged on the negative side of the X-axis of the rotation center axis. FIG. 15(b) is an enlarged side view of the mirror according to a modification in which the light source and the collimator lens are arranged on the negative side of the X-axis of the rotation center axis.

Embodiments of the present invention will be described below with reference to the drawings. For convenience, mutually orthogonal X, Y, and Z axes are shown in each figure. The Z-axis positive direction is the height direction of the distance measuring device 1.

FIG. 1 is a perspective view showing the configuration of a distance measuring device 1. As shown in FIG.

As shown in FIG. 1, the distance measuring device 1 includes a cylindrical fixed part 10 and a rotating part 20 rotatably disposed on the fixed part 10. The rotating part 20 includes two support members 21 and 22 having different diameters. A support member 22 is installed on the upper surface of the support member 21, and the rotating section 20 is configured. An opening 22a is provided in the side surface of the support member 22. Laser light (hereinafter referred to as "projection light") is projected from the aperture 22a toward the distance measurement area, and the laser light reflected at the distance measurement area (hereinafter referred to as "reflected light") is taken into the interior through the aperture 22a. .

The rotating section 20 rotates around a rotation center axis R10 that is parallel to the Z-axis and passes through the center of the rotating section 20. As the rotating section 20 rotates, the optical axis of the projection light projected from the aperture 22a rotates around the rotation center axis R10. Along with this, the distance measurement area (scanning position of the projection light) also rotates. As described later, the distance measurement device 1 performs distance measurement based on the time difference (time of flight) between the timing of projecting the projection light onto the distance measurement area and the timing of receiving the reflected light from the distance measurement area. Measure the distance to objects in the area. As the rotating part 20 rotates once around the rotation center axis R10 as described above, the distance measuring device 1 can measure the distance to an object existing within a 360° circumferential range.

FIG. 2 is a sectional view showing the configuration of the distance measuring device 1. As shown in FIG.

FIG. 2 shows a cross-sectional view of the distance measuring device 1 shown in FIG. 1 taken along a plane parallel to the XZ plane at the center position in the Y-axis direction. In FIG. 2, the projected light emitted from the light source 31 and directed toward the distance measurement area is shown by a broken line, and the reflected light from the distance measurement area is shown by a dash-dotted line.

As shown in FIG. 2, the fixing part 10 includes a cylindrical support base 11, a plurality of coils 12, a yoke 13, and a cover 14. The support base 11 is made of resin, for example. The lower surface of the support base 11 is covered with a circular dish-shaped cover 14.

The support member 21 is installed on the support base 11 via a cylindrical bearing 24. The bearing 24 has a structure in which a plurality of bearing balls 24c are arranged circumferentially between an inner cylinder 24a and an outer cylinder 24b. The support member 21 is formed with a cylindrical tube portion 21a that projects in the negative direction of the Z-axis, and the support base 11 is formed with a cylindrical tube portion 11a that projects in the positive direction of the Z-axis. The outer diameter of the cylindrical portion 11a is slightly larger than the inner diameter of the inner tube 24a of the bearing 24, and the inner diameter of the cylindrical portion 21a is slightly smaller than the outer diameter of the outer tube 24b of the bearing 24. A bearing 24 is fitted between the cylindrical portion 11a and the cylindrical portion 21a, and the support member 21 is supported by the support base 11 so as to be rotatable about the rotation center axis R10.

The support base 11 has a cylindrical wall portion 11b formed on the outside of the cylindrical portion 11a. The center axis of the wall portion 11b is aligned with the rotation center axis R10. A yoke 13 is fitted into the outer periphery of the wall portion 11b. The yoke 13 includes a plurality of protrusions 13a that protrude radially from a ring-shaped base. The intervals between the protrusions 13a in the circumferential direction are constant. A coil 12 is wound and attached to each protrusion 13a.

A stepped portion 21b continuous in the circumferential direction is formed on the outer peripheral portion of the support member 21. A plurality of magnets 23 are installed in this stepped portion 21b without gaps in the circumferential direction. Adjacent magnets 23 have different inner polarities.

These magnets 23 face the protrusion 13a of the yoke 13. Therefore, by controlling the current to the coil 12, the rotating part 20 is rotationally driven about the rotation center axis R10. The coil 12, the yoke 13, and the bearing 24 together with the rotating section 20 constitute a driving section that rotates the mirror 34 about the rotation center axis R10.

The distance measuring device 1 has an optical system including a light source 31, a collimator lens 32, a holder 33, a mirror 34, a condenser lens 35, an optical unit 36, a filter 37, a photodetector 38, It is equipped with The light source 31 is held in a holder 33 together with a collimator lens 32 . The light source 31, the collimator lens 32, and the mirror 34 constitute a projection optical system that projects the projection light onto the distance measurement area.

The light source 31 is, for example, a semiconductor laser, and emits laser light (projection light). The light source 31 is driven by current from the support base 11 side through wiring (not shown) and emits light. The emission optical axis of the light source 31 is parallel to the Z axis. The projection light emitted from the light source 31 is made into parallel light by the collimator lens 32. The parallelized projection light enters a mirror 34 arranged above a condensing lens 35 . The light source 31 and the collimator lens 32 are installed on the condenser lens 35 while being held by the holder 33 . A circular hole penetrating vertically is formed in the center of the condenser lens 35, and a cylindrical holder 33 is fitted into this hole.

The mirror 34 is a reflective mirror having a reflective surface 34a on one side. The center position of the reflective surface 34a is substantially aligned with the rotation center axis R10. The reflective surface 34a has a substantially square shape when viewed in the Z-axis direction. The mirror 34 is installed on the support member 22 of the rotating section 20 so that the reflective surface 34a is inclined at 45 degrees with respect to the rotation center axis R10.

The projected light that has entered the mirror 34 via the collimator lens 32 is reflected by the mirror 34 in a direction perpendicular to the rotation center axis R10. Thereafter, the projected light passes through the aperture 22a and is projected onto the ranging area.

When an object exists in the distance measurement area, the projection light projected onto the distance measurement area from the aperture 22a is reflected by the object and heads toward the aperture 22a again. The projection light (reflected light) reflected by the object in this way is taken in through the aperture 22a and guided to the mirror 34. Thereafter, the reflected light is reflected by the mirror 34 in the negative Z-axis direction. The light reflected by the mirror 34 is converged by the condenser lens 35. The optical axis of the condensing lens 35 is aligned with the rotation center axis R10.

Thereafter, the reflected light passes through the optical unit 36, the hole 11c formed in the support base 11, and the filter 37, and is focused on the photodetector 38. The optical unit 36 includes a transparent sheet 110 and a reflective member 120. The transparent sheet 110 is placed between the condenser lens 35 and the photodetector 38, and the reflective member 120 is placed between the transparent sheet 110 and the photodetector 38. The configuration of the optical unit 36 will be explained later with reference to FIGS. 3(a) and 3(b). The filter 37 is configured to transmit light in the wavelength band of the laser light (projection light) emitted from the light source 31 and block light in other wavelength bands.

The photodetector 38 receives the reflected light focused by the condensing lens 35 on a light receiving surface 38a, and outputs a detection signal according to the amount of received light. The photodetector 38 is composed of, for example, a PIN photodiode or an avalanche photodiode. A detection signal from the photodetector 38 is output to a circuit section arranged on a circuit board (not shown).

Note that in this embodiment, since the light source 31 and the collimator lens 32 are installed in the condenser lens 35, a part of the reflected light taken in through the aperture 22a is blocked by the holder 33, and the light is not detected by the photodetector. The light is not focused on 38. For example, most of the reflected light in the range shown by a dashed line near the center of the condenser lens 35 in FIG. 2 is blocked by the holder 33.

FIG. 3(a) is a top view schematically showing the configuration of the optical unit 36 when viewed in the negative direction of the Z-axis, and FIG. 3(b) is a top view of the optical unit 36 when viewed in the positive direction of the Z-axis. FIG. 2 is a bottom view schematically showing the configuration of the FIG. FIG. 3(c) is a cross-sectional view schematically showing the configuration of the optical unit 36 when the AA' cross section of the optical unit 36 shown in FIGS. 3(a) and 3(b) is viewed in the negative direction of the Y-axis. be. The A-A' cross section is a cross section parallel to the XZ plane passing through the center C10 (see FIGS. 3(a) and 3(b)).

As shown in FIG. 3(c), the optical unit 36 includes a transparent sheet 110 and a reflective member 120. The transparent sheet 110 is integrated into the reflective member 120 by attaching the outer edge portion of the light emitting surface 112 of the transparent sheet 110 to the upper surface 121b of the reflective member 120.

As shown in FIGS. 3(a) and 3(c), the transparent sheet 110 is a thin, circular sheet centered on the center C10 when viewed in the Z-axis direction. The center C10 is the center position of the transparent sheet 110 and the center position of the opening 122a of the reflective member 120. The transparent sheet 110 is made of, for example, acrylic. Transparent sheet 110 has a high transmittance (eg, 98%) so that most of the reflected light is transmitted. Note that the transparent sheet 110 only needs to be made of a material with high transmittance, and may be made of polycarbonate, glass, transparent resin, or the like.

The surface of the transparent sheet 110 on the Z-axis positive side is an entrance surface 111 into which reflected light enters, and the surface of the transparent sheet 110 on the Z-axis negative side is an exit surface 112 from which reflected light is emitted. Optical thin films 111a and 112a are arranged on the entrance surface 111 and the exit surface 112, respectively, to increase reflectance. The optical thin films 111a, 112a are arranged, for example, by vapor deposition of a dielectric material. Note that the optical thin films 111a and 112a may be separately formed and then attached to the transparent sheet 110.

As shown in FIGS. 3(b) and 3(c), the reflecting member 120 is a cylindrical member in which a side surface portion 121 and a bottom surface portion 122 are integrally formed. The reflective member 120 is made of aluminum, for example. Note that the reflective member 120 may be made of stainless steel, plastic, or the like.

The side surface portion 121 has a cylindrical side surface shape. An opening 121a and an upper surface 121b are formed at the end of the side surface portion 121 on the Z-axis positive side. The opening 121a has a circular shape, and the inside of the side surface portion 121 is open to the positive side of the Z-axis through the opening 121a. The upper surface 121b is formed outside the opening 121a over the entire circumference in the circumferential direction centering on the center C10. The upper surface 121b is a plane parallel to the XY plane.

The bottom portion 122 is formed at the end of the side surface portion 121 on the Z-axis negative side, and has a flat plate shape parallel to the XY plane. An opening 122a is formed in the center of the bottom part 122, passing through the bottom part 122 in the Z-axis direction. The opening 122a has a circular shape, and the diameter of the opening 122a is smaller than the outer diameter of the bottom portion 122. The optical unit 36 is installed on the support base 11 (see FIG. 2) so that the rotation center axis R10 passes through the center C10. Thereby, the center C10 of the aperture 122a is aligned with the optical axis of the condenser lens 35.

A reflective surface 122b is formed around the opening 122a on the upper surface (Z-axis positive side surface) of the bottom surface portion 122. Since the reflective member 120 is made of aluminum, the reflective surface 122b becomes a reflective surface that reflects light. Note that the reflective surface 122b may be formed by coating the top surface of the bottom part 122 with a reflective film after molding the reflective member 120, or by applying a mirror finish to the top surface of the bottom part 122. may be formed. Further, the reflective surface 122b may be formed by a mirror separately installed on the upper surface of the bottom portion 122.

FIGS. 4(a) and 4(b) are diagrams schematically showing the luminous flux of reflected light reflected by an object in the distance measurement area in the case of a comparative example, and FIGS. FIG. 4 is a diagram schematically showing a luminous flux of light reflected by an object in a distance measurement area in the case of a distance measurement area. FIGS. 4(a) to 5(b) show cut surfaces taken along the XZ plane passing through the rotational center axis R10 (see FIG. 2). In FIGS. 4(a) to 5(b), illustration of the light source 31, collimator lens 32, mirror 34, and filter 37 is omitted for convenience.

As shown in FIGS. 4A and 4B, in the configuration of the comparative example, the optical unit 36 (transparent sheet 110 and reflective member 120) is omitted.

The amount of light taken into the aperture 22a (see FIG. 2) of the distance measuring device 1 becomes small when the object to be measured is located far from the distance measuring device 1. That is, the amount of light taken into the aperture 22a is inversely proportional to the square of the distance to the object. Therefore, as shown in the comparative example of FIG. 4(a), at a position where the reflected light from the object to be measured at the farthest position from the distance measuring device 1 is converged on the light receiving surface 38a by the condensing lens 35, A photodetector 38 is arranged. That is, the condensing lens 35 is configured to have a focal length that condenses reflected light from the farthest distance within the distance range of the measurement target onto the light receiving surface 38a. In this way, weak reflected light from objects located far away can be well received.

However, as shown in FIG. 4(a), when the photodetector 38 is arranged based on the farthest distance, as shown in FIG. , the reflected light condensed by the condenser lens 35 comes off the light-receiving surface 38a. That is, the reflected light reflected in a predetermined distance range from the closest distance to the farthest distance within the distance range of the measurement target is no longer received by the light receiving surface 38a. Therefore, in the case of the comparative example, although light from a distant object can be properly received, light from a nearby object cannot be properly received.

In contrast, in this embodiment, as shown in FIGS. 5(a) and 5(b), an optical unit 36 (transparent sheet 110 and reflective member 120) is provided between the condenser lens 35 and the photodetector 38. It is located. In this embodiment as well, as in the comparative example, the condenser lens 35 is configured to have a focal length that condenses reflected light from the farthest distance within the distance range of the measurement target onto the light receiving surface 38a. Further, the size and position of each part of the optical unit 36 are adjusted so that almost all of the reflected light from the farthest distance converged by the condenser lens 35 passes through the aperture 122a of the reflection member 120 via the transparent sheet 110. Set.

Further, as shown in FIG. 5B, at least a part of the reflected light reflected in a predetermined distance range from the closest distance to the farthest distance of the measurement target and converged by the condenser lens 35 is transmitted to the reflective member 120. The size and position of each part of the reflecting member 120 are set so that the light is reflected by the reflecting surface 122b of the transparent sheet 110, and finally guided to the light receiving surface 38a.

Specifically, the distance between the transparent sheet 110 and the reflective surface 122b is defined by the height of the reflective member 120 (the length of the side surface portion 121 in the Z-axis direction). Therefore, the height of the reflective member 120 is adjusted so that the reflected light reflected by the reflective surface 122b is reflected by the transparent sheet 110 and appropriately guided to the photodetector 38. Further, the upper surface of the bottom portion 122 other than the opening 122a constitutes a reflective surface 122b. Here, the amount of light reflected from the short distance range by the reflective surface 122b is determined by the width of the bottom portion 122 in the radial direction of the opening 122a (in other words, the diameter of the opening 122a). Therefore, the width of the bottom portion 122 is adjusted so that the reflected light reflected by the reflective surface 122b is reflected by the transparent sheet 110 and appropriately guided to the photodetector 38.

Note that if the width of the bottom portion 122 is too wide and the diameter of the aperture 122a is too small, reflected light from a long distance range will be blocked by the reflective surface 122b, and the amount of reflected light passing through the aperture 122a will decrease. Therefore, the width of the bottom portion 122 and the diameter of the opening 122a are set to a size that allows not only reflected light from a short distance but also reflected light from a long distance to be properly guided to the photodetector 38. need to be done.

In addition, the position of the optical unit 36 in the Z-axis direction is determined based on the relationship between the distance between the transparent sheet 110 and the reflective surface 122b and the width of the bottom portion 122 (the diameter of the opening 122a), so that reflected light from a short distance and It is adjusted to a position where reflected light from a long distance range can be appropriately guided to the photodetector 38.

In this embodiment, when the object to be measured is at the farthest distance, as shown in FIG. The light passes through the transparent sheet 110, passes through the opening 122a of the reflection member 120, and is focused on the light receiving surface 38a. At this time, the reflected light that has passed through the transparent sheet 110 hardly hits the reflective surface 122b.

In this embodiment, when the object to be measured is within a predetermined range from the closest distance, as shown in FIG. 5B, the inner part (center C10 (FIG. (a) and (b)) passes through the aperture 122a and then passes through a position away from the photodetector 38, similar to FIG. 4(b). On the other hand, the outer portion of the reflected light converged by the condenser lens 35 enters the reflective surface 122b and is reflected by the reflective surface 122b. A part of the reflected light reflected by the reflective surface 122b is further reflected by the transparent sheet 110, and is focused on the light receiving surface 38a.

More specifically, a part of the reflected light reflected by the reflective surface 122b is reflected by the output surface 112 of the transparent sheet 110 and guided to the light receiving surface 38a. Further, of the reflected light reflected by the reflective surface 122b, a portion of the reflected light that has passed through the output surface 112 of the transparent sheet 110 is reflected by the incident surface 111 of the transparent sheet 110 and guided to the light receiving surface 38a.

In this way, in the case of the embodiment, the reflected light that has passed through the opening 122a and the reflected light that has been reflected by the reflective surface 122b and the transparent sheet 110 are guided to the light receiving surface 38a in a complementary manner, regardless of the distance to the object. First, reflected light can be guided to the light receiving surface 38a.

Next, a simulation regarding reflected light rays performed by the inventor will be described.

FIG. 6 is a diagram showing the sizes of each part set in this simulation.

In this simulation, light with a wavelength of 905 nm was emitted from the light source 31 placed at the center of the condenser lens 35 in the positive direction of the Z-axis. The diameter φ1 of the beam spot BS at the time of emission from the light source 31 was set to 4 mm. The light emitted in the positive direction of the Z-axis is reflected by an object surface R parallel to the XY plane, which is placed at a predetermined distance from the condenser lens 35, and the reflected light from the object surface R is reflected by the condenser lens 35. On the other hand, it was made incident in the negative direction of the Z axis.

The outer diameter (diameter of the optical surface on the negative side of the Z-axis) φ2 of the condenser lens 35 was set to 25 mm. The diameter φ3 of the holder 33 for blocking reflected light passing through the central portion of the condenser lens 35 was set to 7.5 mm. The focal length of the condenser lens 35 was set to 30 mm. The condenser lens 35 was made of polycarbonate. The light receiving surface 38a was placed at the focal length of the condenser lens 35.

The transparent sheet 110 was made of acrylic. The length (thickness) d1 of the transparent sheet 110 in the Z-axis direction was 1 mm. In this simulation, the optical thin films 111a and 112a (see FIG. 3(c)) were omitted. The ratio of surface reflection (surface reflectance) caused by the difference in refractive index between the transparent sheet 110 and air was set to 4% on both the entrance surface 111 and the exit surface 112.

The reflective member 120 was made of aluminum. The reflective member 120 was composed of only the bottom portion 122 (see FIG. 3(c)). The length (thickness) d2 of the reflective member 120 in the Z-axis direction was set to 0.4 mm. The diameter φ4 of the opening 122a was set to 1.8 mm. The gap d3 between the transparent sheet 110 and the reflective member 120 was set to 2.6 mm. The gap d4 between the reflecting member 120 and the photodetector 38 was set to 1.5 mm. The axial distance d5 between the Z-axis negative side surface of the condenser lens 35 and the transparent sheet 110 was set to 20 mm. The diameter φ5 of the light receiving surface 38a of the photodetector 38 was set to 0.5 mm.

Under these conditions, the inventor moved the object surface R in the Z-axis direction and changed the distance from the light receiving surface 38a to the object surface R between 100 mm and 4000 mm or between 130 mm and 4000 mm, and simulated the light beam. went. Specifically, the distance range of the measurement target was 130 mm to 4000 mm in the comparative example, and 100 mm to 4000 mm in the embodiment. The closest distance was 130 mm in the comparative example and 100 mm in the embodiment. The farthest distance in the comparative example and the embodiment was 4000 mm.

In this simulation, when the distance to the object surface R was 4000 mm (the farthest distance), almost all of the reflected light transmitted through the transparent sheet 110 and passed through the opening 122a of the reflective member 120. Further, when the distance to the object surface R is 4000 mm (farthest distance), the reflected light that has passed through the condenser lens 35 is converged on the light receiving surface 38a of the photodetector 38 due to the convergence effect of the condenser lens 35. A photodetector 38 was placed. Then, while changing the distance to the object surface R, the amount of reflected light received by the light receiving surface 38a was calculated.

FIGS. 7A and 7B are diagrams showing rays of reflected light when the object surface R is at a long distance (4000 mm) and a short distance (150 mm), respectively, in a comparative example. FIGS. 8A and 8B are diagrams showing rays of reflected light when the object surface R is at a long distance (4000 mm) and a short distance (150 mm), respectively, in the embodiment. 7(a) to FIG. 8(b) are side views of cut surfaces taken along the XZ plane passing through the optical axis of the condenser lens 35, viewed in the negative direction of the Y-axis.

As shown in FIGS. 7(a) and 8(a), when the distance to the object surface R is 4000 mm, in both the comparative example and the embodiment, the reflected light converged by the condenser lens 35 is The light was focused on the light receiving surface 38a.

As shown in FIG. 7(b), in the comparative example, when the distance to the object surface R was 150 mm, almost all of the reflected light converged by the condenser lens 35 was not converged on the light receiving surface 38a. . On the other hand, as shown in FIG. 8(b), in the embodiment, when the distance to the object surface R is 150 mm, among the reflected light converged by the condenser lens 35, the reflected light near the periphery of the aperture 122a is After being reflected by the reflective surface 122b, the light was further reflected by the transparent sheet 110 and focused on the light receiving surface 38a.

Note that, for convenience, in FIG. 8(b), only the light rays reflected by the output surface 112 of the transparent sheet 110 among the reflected light reflected by the reflection surface 122b are illustrated. However, in reality, since the transparent sheet 110 is thick, part of the reflected light reflected by the reflective surface 122b is transmitted through the output surface 112 of the transparent sheet 110 and then reflected by the incident surface 111, as described above. Then, the light is guided to the light receiving surface 38a. Therefore, the reflected light reflected by the reflective surface 122b and guided to the photodetector 38 also includes this component of the light beam.

FIG. 9 is a graph showing simulation results according to the comparative example and the embodiment. The horizontal axis is the distance (mm) from the light receiving surface 38a to the object surface R, and the vertical axis is the amount of light received (arbitrary unit) when the amount of light received by the light receiving surface 38a at a distance of 4000 mm is 1. In FIG. 9, the amount of received light that allows proper measurement without being affected by noise or the detection sensitivity of the photodetector 38 is 1 or more.

In the case of the comparative example, when the distance to the object surface R became 300 mm or less, the amount of received light decreased rapidly and became less than 1. On the other hand, in the case of the embodiment, as shown in FIG. 8(b), reflected light from a short distance is guided to the light receiving surface 38a by the reflective surface 122b and the transparent sheet 110, so that the distance to the object surface R is Even when the distance was 300 mm or less, the amount of received light was maintained at a high level. In this way, in the embodiment, it was confirmed that the decrease in the amount of received light can be suppressed even when the distance to the object is short.

Note that in both the comparative example and the embodiment, when the distance to the object surface R was between 1000 mm and 4000 mm, the amount of received light decreased as the distance to the object surface R became longer. Here, as described above, the photodetector 38 is arranged so that when the distance to the object surface R is 4000 mm, the reflected light is converged on the light receiving surface 38a. As a result, when the distance to the object surface R is 1000 mm to 4000 mm, reflected light is guided to the light receiving surface 38a with almost no leakage. However, when the distance to the object surface R is 1000 mm to 4000 mm, the reflected light itself entering the condenser lens 35 becomes weak, so the amount of received light decreases in both the comparative example and the embodiment.

As described above, in the embodiment, the reflective surface 122b and The transparent sheet 110 and the reflective member 120 are set so that the light reflected by the transparent sheet 110 is guided to the photodetector 38. Thereby, the measurable distance range can be expanded.

Note that the distance range in which the amount of received light is supplemented by the reflective surface 122b and the transparent sheet 110 is not limited to the distance range (100 to 300 mm) shown in FIG. Even in this distance range, the reflected light reflected by the reflective surface 122b and the transparent sheet 110 may be guided to the photodetector 38.

In other words, the amount of light received by the photodetector 38 is set to be equal to or greater than a predetermined amount of light (in the case of the above simulation, the amount of received light is 1) that allows proper measurement without being affected by noise or the detection sensitivity of the photodetector 38. The transparent sheet 110 and the reflective member 120 may be set. Specifically, the thickness d1 of the transparent sheet 110, the gap d3 between the transparent sheet 110 and the reflective member 120, the diameter φ4 of the opening 122a, and the surface reflectance of the transparent sheet 110 are set so that the amount of received light is equal to or greater than the predetermined amount of light. should be set. In addition, the focal length of the condenser lens 35, the axial distance d5 between the condenser lens 35 and the transparent sheet 110, the gap d4 between the reflective member 120 and the photodetector 38, etc. may be set as appropriate.

FIG. 10 is a diagram showing the configuration of the circuit section of the distance measuring device 1. As shown in FIG.

The distance measuring device 1 includes a controller 101, a laser drive circuit 102, a rotation drive circuit 103, and a signal processing circuit 104 as circuit components.

The controller 101 includes an arithmetic processing circuit such as a CPU and a memory, and controls each part according to a predetermined control program. The laser drive circuit 102 drives the light source 31 under control from the controller 101. The rotation drive circuit 103 conducts current to the coil 12 under control from the controller 101. For example, the controller 101 controls the rotational drive circuit 103 so that the rotating section 20 rotates at a predetermined rotational speed. Accordingly, the intensity and timing of the current conducted from the rotation drive circuit 103 to the coil 12 are adjusted.

The signal processing circuit 104 performs amplification and noise removal processing on the detection signal input from the photodetector 38 and outputs it to the controller 101 . The communication interface 105 is an interface for communicating with a device in which the distance measuring device 1 is installed.

In the distance measuring operation, the controller 101 controls the rotation drive circuit 103 to rotate the mirror 34 together with the rotation unit 20, and controls the laser drive circuit 102 to emit a predetermined pulse of laser light from the light source at each predetermined timing. output from 31. The controller 101 detects the reception timing of the laser light pulse emitted at each emission timing based on the detection signal of the photodetector 38 inputted from the signal processing circuit 104. Then, the controller 101 measures the distance to the object present in the ranging area at each emission timing, based on the time difference (time of flight) between the laser beam emission timing and the light reception timing.

The controller 101 transmits the distance data calculated in this way via the communication interface 105 to the device in which the distance measuring device 1 is installed. On the device side, based on the received distance data, distances to objects existing in a 360° surrounding are acquired, and predetermined control is executed.

<Effects of embodiment>
As described above, according to the embodiment, the following effects are achieved.

As shown in FIG. 5B, at least a portion of the reflected light reflected from an object within a distance range shorter than a predetermined distance is reflected by the reflective surface 122b of the reflective member 120, and then reflected by the transparent sheet 110. It is reflected and guided to the photodetector 38. This makes it possible to increase the amount of received reflected light from a short distance range. Further, as shown in FIG. 5A, reflected light from a long distance range passes through the opening 122a of the reflection member 120 and is focused on the photodetector 38. Therefore, the amount of received reflected light from a long distance range can also be maintained high. Therefore, the reflected light from the object can be more appropriately guided to the photodetector 38 within the distance range of the measurement target.

The aperture 122a of the reflective member 120 is circular, and the center C10 of the aperture 122a is aligned with the optical axis of the condenser lens 35. According to this configuration, the outer peripheral portion of the reflected light reflected from an object within a distance range shorter than a predetermined distance can be made incident on the reflective surface 122b over the entire circumference and guided to the photodetector 38. Thereby, the amount of reflected light guided to the photodetector 38 can be increased. Further, reflected light from a distant object is guided to the photodetector 38 through the aperture 122a. Therefore, the photodetector 38 can smoothly receive reflected light from an object from a long distance.

An optical thin film for increasing reflectance is disposed on at least one of the entrance surface 111 and the exit surface 112 of the transparent sheet 110. Specifically, optical thin films 111a and 112a are arranged on the entrance surface 111 and the exit surface 112, respectively. Thereby, the reflected light reflected by the reflective surface 122b can be guided to the photodetector 38 more efficiently by the optical thin film. Therefore, the amount of reflected light received by the photodetector 38 from a short distance range can be increased.

For example, the reflectance of the entrance surface 111 and the exit surface 112 of the transparent sheet 110 is 4%, and the reflectance of the entrance surface 111 and the exit surface 112 when an optical thin film is provided on the entrance surface 111 and the exit surface 112 of the transparent sheet 110 is 4%. If it is 6%, the ratio of reflected light that passes through the transparent sheet 110 when an optical thin film is provided is (100%-6%)^2=88.4%. The ratio of the reflected light reflected by the transparent sheet 110 after being reflected by the reflective surface 122b is 88.4%×(100%−(100%−6%)^2)=10.3%. On the other hand, if no optical thin film is provided in this case, the ratio of reflected light that passes through the transparent sheet 110 will be (100%-4%)^2=92.2%. The ratio of the reflected light reflected by the transparent sheet 110 after being reflected by the reflective surface 122b is 92.2%×(100%−(100%−4%)^2)=7.2%. By providing the optical thin film in this way, the amount of reflected light reflected by the reflective surface 122b and the transparent sheet 110 and guided to the photodetector 38 can be increased.

The reflecting member 120 is a cylindrical member whose top surface 121b is open with an opening 121a, and an opening 122a is formed in the bottom surface portion 122 (bottom surface) of the reflecting member 120. The transparent sheet 110 is attached to the upper surface 121b of the reflective member 120 and is integrated with the reflective member 120. According to this configuration, since the transparent sheet 110 and the reflective member 120 are integrated, when arranging these members in the optical system, the positions of the transparent sheet 110 and the reflective member 120 (reflective surface 122b) need to be adjusted. There is no need to do this. Therefore, the transparent sheet 110 and the reflective member 120 can be easily arranged in the optical system.

As shown in FIG. 2, a light source 31 that emits laser light (projection light) is embedded in the center of the condenser lens 35. In this way, when the light source 31 is embedded in the center of the condensing lens 35, the reflected light is blocked by the light source 31, so that among the reflected light directed toward the condensing lens 35, the reflected light that is incident on the outer peripheral area of the condensing lens 35 is Only the light will be focused on the photodetector 38. Therefore, in this configuration, if the transparent sheet 110 and the reflective member 120 are not arranged as in the above comparative example, the condensing area of the reflected light may deviate from the photodetector 38 depending on the distance of the object. . On the other hand, according to the distance measuring device 1 of the embodiment, since the transparent sheet 110 and the reflective member 120 are arranged as described above, even if the light source 31 is embedded in the condensing lens 35 in this way, the object The reflected light can be guided to the photodetector 38 regardless of its distance.

<Example of change>
The configuration of the distance measuring device 1 can be modified in various ways other than the configuration shown in the above embodiment.

For example, in the embodiment described above, the reflecting member 120 has a cylindrical shape in which the upper surface 121b is opened through the opening 121a, but is not limited to this, and may have a rectangular cylindrical shape in which the upper surface 121b is opened through the opening 121a. . For example, the reflecting member 120 has a rectangular tube shape, and may be square when viewed in the Z-axis direction, as shown in FIG. 11(a). When the shape of the reflective member 120 is changed in this way, the shape of the transparent sheet 110 is also changed to match the outer shape of the upper surface 121b of the reflective member 120.

Further, in the above embodiment, the transparent sheet 110 and the reflective member 120 are integrated by attaching the transparent sheet 110 to the upper surface 121b of the reflective member 120 in which the side surface portion 121 and the bottom surface portion 122 are integrally formed. It was done. However, the configuration in which the transparent sheet 110 and the reflective member 120 are integrated is not limited to this. For example, when the reflective member 120 is a plate-shaped member having an opening 122a, a ring-shaped member or a cylindrical member with open upper and lower surfaces is interposed between the transparent sheet 110 and the reflective member 120, and the transparent sheet 110 and the reflecting member 120 may be integrated.

Furthermore, in the embodiments described above, the transparent sheet 110 and the reflective member 120 do not necessarily have to be integrated, and may be arranged separately in the optical system. For example, the transparent sheet 110 and the reflective member 120 may be separately installed on the support base 11 (see FIG. 2). However, when the transparent sheet 110 and the reflective member 120 are individually installed on the support base 11, it is necessary to separately adjust the positions of the transparent sheet 110 and the reflective member 120. Therefore, in order to save time and effort in position adjustment, it is preferable that the transparent sheet 110 and the reflective member 120 be integrated as in the above embodiment.

Further, in the embodiment described above, the opening 122a provided in the bottom surface portion 122 of the reflecting member 120 is circular, but the opening 122a is not limited to this and may have another shape.

For example, the opening 122a may have the shape shown in FIGS. 11(b) to 11(d). In the modified examples shown in FIGS. 11(b) to 11(d), the opening 122a has a square shape, a circular shape with a cutout 122c on the outer periphery, and a shape in which semicircles with different diameters are combined. . In any of the modified examples shown in FIGS. 11(b) to 11(d), when the object to be measured is at the farthest distance, the area of the reflected light converged by the condenser lens 35 (FIGS. 11(b) to 11(d)) The size of the opening 122a is set so that the area indicated by the broken line in (d) is contained within the opening 122a. In these cases, since the area of the aperture 122a is expanded compared to the above embodiments, reflected light from a long distance range can be more reliably guided to the light receiving surface 38a of the photodetector 38.

Furthermore, when the aperture 122a is larger than in the embodiment, the amount of reflected light reflected by the reflective surface 122b among the reflected light from a nearby object decreases, so the amount of reflected light guided to the light receiving surface 38a decreases. decreases. Therefore, if the amount of reflected light from the short distance range is too large, by changing the shape and size of the aperture 122a, the amount of reflected light from the short distance range guided to the photodetector 38 can be adjusted to a desired value. Light intensity can be set.

Further, in the above embodiment, the reflective surface 122b of the reflective member 120 is a surface parallel to the XY plane, but the invention is not limited to this, and the reflected light reflected by the reflective surface 122b and the transparent sheet 110, The reflective surface 122b may have other shapes as long as the reflected light passing through the reflective surface 122a is guided to the photodetector 38 in a complementary manner. For example, the reflective surface 122b may be inclined so as to be displaced in one direction parallel to the rotation center axis R10 as the distance from the rotation center axis R10 increases.

For example, as shown in FIG. 12(a), the reflective surface 122b may be a plane having a predetermined acute angle with respect to the XY plane. In the modified example of FIG. 12(a), the reflective surface 122b matches the side surface of the cone. Moreover, as shown in FIG. 12(b), the reflective surface 122b may be a curved surface. When the reflective surface 122b is configured as a curved surface, the reflective surface 122b may have, for example, an arc shape, an elliptical shape, or a parabolic shape in a cross section taken by a plane including the rotation center axis R10.

Further, among the reflected light reflected by the reflective surface 122b, both the reflected light reflected by the output surface 112 of the transparent sheet 110 and the reflected light reflected by the incident surface 111 of the transparent sheet 110 are properly detected by the photodetector. The thickness of the transparent sheet 110 may be set such that the transparent sheet 110 is guided to

13A and 13B show the luminous flux of reflected light from the farthest distance and the luminous flux of reflected light reflected within a predetermined range from the closest distance, respectively, when the transparent sheet 110 has a predetermined thickness. It is a figure shown typically. In the modified example shown in FIGS. 13(a) and 13(b), the luminous flux of reflected light near the outer edge is indicated by a broken line.

As shown in FIG. 13(a), the reflected light from the farthest distance passes through the inside of the aperture 122a and is focused on one point on the photodetector 38. On the other hand, as shown in FIG. 13(b), a part of the reflected light reflected within a predetermined range from the closest distance is reflected by the reflective surface 122b of the reflective member 120 and the output surface 112 of the transparent sheet 110. At this time, among the reflected light reflected by the reflective surface 122b, both the reflected light reflected by the output surface 112 and the reflected light reflected by the input surface 111 after passing through the output surface 112 are detected by the photodetector. The thickness of the transparent sheet 110 is set so that the transparent sheet 110 is guided to the transparent sheet 38.

According to this configuration, both the reflected light reflected by the output surface 112 and the reflected light reflected by the incident surface 111 can be properly guided to the photodetector 38. Therefore, the amount of reflected light received by the photodetector 38 from a short distance range can be increased. The thickness of the transparent sheet 110 may be optimized to a value that can appropriately increase the amount of reflected light received from a short distance range.

Further, in the above embodiment, the optical thin film is placed on both the entrance surface 111 and the exit surface 112 of the transparent sheet 110, but the present invention is not limited to this, and the optical thin film is placed on either the entrance surface 111 or the exit surface 112. The optical thin film may not be disposed on either the entrance surface 111 or the exit surface 112. However, in the case where the optical thin film is not disposed, the amount of reflected light reflected by the output surface 112 or the input surface 111 and guided to the photodetector 38 out of the reflected light reflected by the reflective surface 122b is different from that of the above embodiment. and decrease. Therefore, if it is desired to increase the amount of reflected light guided to the photodetector 38, it is preferable to arrange an optical thin film on both the entrance surface 111 and the exit surface 112 as in the above embodiment. Note that the optical thin film may be provided inside the transparent sheet 110 as a layered structure.

Further, in the embodiment described above, the transparent sheet 110 may be provided with a lens function that focuses the reflected light from the reflective surface 122b onto the photodetector 38.

Further, in the above embodiment, the light source 31 and the collimator lens 32 are installed so as to be embedded in the center of the condenser lens 35, but the light source 31 and the collimator lens 32 are not limited to this, but the light source 31 and the collimator lens 32 can be placed by other methods. may be done. For example, the light source 31 and the collimator lens 32 may be arranged as in the modified examples shown in FIGS. 14(a) to 14(c), or as in the modified examples shown in FIGS. 15(a) and 15(b). It's okay.

FIGS. 14(a) to 14(c) are diagrams showing configurations of modified examples in which the light source 31 is arranged on the positive side of the X-axis of the condenser lens 40. FIG. FIG. 14(a) is a side perspective view schematically showing the configuration of the distance measuring device 1 according to this modification, and FIG. 14(b) is a perspective view showing the configuration of the condenser lens 40 according to this modification. FIG. 14C is a perspective view showing the configuration of a lens barrel 50 according to this modification.

As shown in FIG. 14(a), in this modified example, a condenser lens 40 is installed in place of the condenser lens 35, compared to the above embodiment. As shown in FIG. 14(b), the condenser lens 40 includes a notch 41 extending from the side edge to the center. In other words, the notch 41 extends from the outer peripheral portion of the condenser lens 40 on the positive side of the X-axis to the optical axis aligned with the rotation center axis R10. Furthermore, the notch 41 in this modification extends through the condenser lens 40 in the Z-axis direction.

A mirror 39 is arranged at the center of the condenser lens 40 to reflect the laser beam (projection light) in the direction of the optical axis of the condenser lens 40 . The laser beam (projection light) enters the condenser lens 40 from the side along the notch 41 and is reflected by the mirror 39 in a direction parallel to the optical axis of the condenser lens 40 (positive Z-axis direction). Here, a light source 31, a collimator lens 32, and a mirror 39 are arranged using a lens barrel 50. As shown in FIG. 14(a), the lens barrel 50 is fitted into the notch 41.

As shown in FIG. 14(c), the lens barrel 50 is a member in which a cylindrical portion 51 extending in the X-axis direction and a cylindrical portion 52 extending in the Z-axis direction are integrally formed. The center axis of the cylindrical portion 52 is aligned with the rotation center axis R10 and the optical axis of the condenser lens 40. The collimator lens 32 is installed near the center inside the cylindrical part 51, and the light source 31 is installed in the opening 51a of the X-axis positive side end of the cylindrical part 51. The mirror 39 is installed inside the joint between the cylindrical portion 51 and the cylindrical portion 52 . When the lens barrel 50 in which the light source 31, the collimator lens 32, and the mirror 39 are installed is fitted into the notch 41 of the condenser lens 40, the light source 31, the collimator lens 32, and the mirror 39 are inserted into the notch 41 of the condenser lens 40, as shown in FIG. 14(a). are lined up in the X-axis direction, and the mirror 39 is positioned at the center of the condenser lens 40.

As shown in FIG. 14(a), the laser light (projection light) emitted from the light source 31 enters the condenser lens 40 from the side along the notch 41, and is reflected by the mirror 39 into the condenser lens 40. It is reflected in the optical axis direction. Specifically, the projection light emitted from the light source 31 in the negative direction of the X-axis passes through the lens barrel 50, is made into parallel light by the collimator lens 32, and is then reflected by the mirror 39 in the positive direction of the Z-axis. , is emitted from the opening 52a at the end of the cylindrical portion 52 on the Z-axis positive side in the Z-axis positive direction.

The projected light emitted from the aperture 52a is reflected in a direction perpendicular to the rotation center axis R10 by the mirror 34 rotating around the rotation center axis R10, and is transmitted through the optical window 1a provided in the distance measuring device 1 to be measured. Projected to the range area. The reflected light from the object in the distance measurement area is taken into the distance measurement device 1 via the optical window 1a, and is reflected by the mirror 34 in the negative direction of the Z-axis. The reflected light reflected by the mirror 34 is condensed by a condensing lens 40, and is guided to a photodetector 38 via an optical unit 36 and a filter 37, as in the above embodiment.

Also in this modified example, the optical unit 36 (transparent sheet 110 and reflective member 120) is provided as in the above embodiment. As a result, reflected light from a long distance within the distance range of the measurement target is focused on the photodetector 38, and reflected light from a short distance within the distance range of the measurement target is also guided to the photodetector 38. I can do it.

Furthermore, according to this modification example, there is no need to incorporate the light source 31 and the drive circuit for driving the light source 31 into the condensing lens 40, so the light source 31 and the drive circuit for the light source 31 are different from those in the above embodiment. , the photodetector 38 and the circuit board on which the photodetector 38 is installed. Further, unlike the embodiment described above, there is no need to arrange a connection wiring connected to the light source 31 directly below the condenser lens 35. Thereby, noise superimposed on the detection signal of the photodetector 38 can be reduced.

Further, according to this modification, only the lens barrel 50 that covers the optical path of the laser beam (projection light) emitted from the light source 31 is disposed inside the condenser lens 40, so that the aperture area of the condenser lens 40 is reduced. The decrease can be suppressed. Thereby, the amount of reflected light guided to the photodetector 38 can be increased. Further, since the collimator lens 32 and the light source 31 can be arranged with a wide interval, the focal length of the collimator lens 32 can be set to be long. Thereby, the optical magnification can be appropriately set to reduce the beam spot on the light receiving surface 38a of the photodetector 38, so that the reflected light from the object in the distance measurement area can be efficiently guided to the photodetector 38.

In the modified examples shown in FIGS. 14(a) to 14(c), the lens barrel 50 is held by the notch 41 that passes through the condenser lens 40 in the Z-axis direction, but the present invention is not limited to this. It may be held by a concave notch extending from the optical axis in the positive direction of the X-axis and open in the positive direction of the Z-axis.

Furthermore, in the configurations of FIGS. 14A to 14C, the light source 31 is installed in the opening 51a of the lens barrel 50, but the light source 31 does not necessarily have to be installed in the opening 51a of the lens barrel 50. For example, the light source 31 may be placed outside the lens barrel 50 so that the light source 31 and the mirror 39 face each other in the X-axis direction, or the laser beam emitted from the light source 31 may be reflected by another mirror. Alternatively, the mirror 39 may be directed along the notch 41. Further, the mirror 39 does not necessarily have to be a separate member from the lens barrel 50. For example, a flat inclined surface may be provided at the connecting portion between the cylindrical portion 51 and the cylindrical portion 52 of the lens barrel 50. The mirror 39 may be configured by mirror finishing.

FIGS. 15A and 15B are diagrams showing a configuration of a modified example in which the light source 31 and the collimator lens 32 are arranged on the negative side of the X-axis of the rotation center axis R10. FIG. 15(a) is a side perspective view schematically showing the configuration of the distance measuring device 1 according to this modification, and FIG. 15(b) is an enlarged side view of the mirror 62 according to this modification.

As shown in FIG. 15(a), in this modification, a light source 31 and a photodetector 38 are installed on the substrate so as to be aligned in the X-axis direction. Furthermore, mirrors 61 and 62 are installed on the fixed part 10 on the Z-axis negative side of the condenser lens 35. Collimator lens 32 is installed between light source 31 and mirror 61. The optical unit 36 is installed between the mirror 62 and the filter 37. Mirror 61 is a total reflection mirror. As shown in FIG. 15(b), the mirror 62 includes a transparent member 62a and a reflective film 62b. The reflective film 62b is provided at the center of the Z-axis positive side surface of the transparent member 62a. No reflective film is formed in the area other than the reflective film 62b.

In this modification, the laser beam emitted from the light source 31 becomes parallel light by the collimator lens 32, and is reflected by the mirror 61 in the positive direction of the X-axis. The laser beam reflected by the mirror 61 enters the reflective film 62b. Thereafter, the laser beam is reflected by the reflective film 62b in the positive Z-axis direction, passes through the condenser lens 35, and is reflected by the mirror 34 to the distance measurement area.

The reflected light from the object in the distance measurement area is reflected by the mirror 34 in the negative direction of the Z-axis, and is condensed by the condensing lens 35. Most of the reflected light focused by the focusing lens 35 passes through the transparent member 62a of the mirror 62. The reflected light that has passed through the mirror 62 is guided to the photodetector 38 via the optical unit 36 and the filter 37, as in the above embodiment.

Also in this modified example, the optical unit 36 (transparent sheet 110 and reflective member 120) is provided as in the above embodiment. As a result, reflected light from a long distance within the distance range of the measurement target is focused on the photodetector 38, and reflected light from a short distance within the distance range of the measurement target is also guided to the photodetector 38. I can do it.

In the modification shown in FIGS. 15(a) and 15(b), the light source 31 and the collimator lens 32 may be arranged on the rotating part 20 side. However, in this case, a configuration for supplying power from the fixed part 10 side to the rotating part 20 side is required. Therefore, in order to stably drive the light source 31 with a simple configuration, it is preferable to arrange the light source 31 on the fixed part 10 side as in the above embodiment.

Note that it is also possible to apply the structure according to the present invention to an apparatus that does not have a distance measurement function and only has a function of detecting whether or not an object exists in the projection direction based on a signal from the photodetector 38. In this case as well, since the reflected light can be guided to the photodetector 38 regardless of the distance to the object, the presence or absence of the object can be appropriately detected.

In addition, the embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims.

1 Distance measuring device 31 Light source (projection optical system)
32 Collimator lens (projection optical system)
34 Mirror (projection optical system)
35 Condensing lens 38 Photodetector 39 Mirror 40 Condensing lens 41 Notch 110 Transparent sheet 111 Incident surface 111a Optical thin film 112 Output surface 112a Optical thin film 120 Reflective member 121 Side part (cylindrical member)
121b Top surface 122 Bottom surface portion (cylindrical member, bottom surface)
122a opening 122b reflective surface

Claims (7)

a projection optical system that projects a laser beam;
a condensing lens that condenses the reflected light of the laser beam reflected by an object;
a photodetector that receives the reflected light focused by the focusing lens;
a transparent sheet disposed between the condenser lens and the photodetector;
a reflective member disposed between the transparent sheet and the photodetector, the reflective member having an aperture and a reflective surface formed around the aperture;
At least a portion of the reflected light reflected from an object within a distance range shorter than a predetermined distance is reflected by the reflective surface, then reflected by the transparent sheet, and guided to the photodetector.
A distance measuring device characterized by: The distance measuring device according to claim 1,
the opening is circular;
the center of the aperture is aligned with the optical axis of the condenser lens;
A distance measuring device characterized by: The distance measuring device according to claim 1 or 2,
An optical thin film for increasing reflectance is disposed on at least one of the incident surface and the exit surface of the transparent sheet.
A distance measuring device characterized by: The distance measuring device according to any one of claims 1 to 3,
Of the reflected light reflected by the reflective surface, both the reflected light reflected by the output surface of the transparent sheet and the reflected light reflected by the incident surface of the transparent sheet are directed to the photodetector. The thickness of the transparent sheet is set so as to be guided.
A distance measuring device characterized by: The distance measuring device according to any one of claims 1 to 4,
The reflective member is a cylindrical member with an open top surface, and the opening is formed in the bottom surface of the reflective member,
The transparent sheet is attached to the upper surface of the reflective member and is integrated with the reflective member.
A distance measuring device characterized by: The distance measuring device according to any one of claims 1 to 5,
A light source that emits the laser beam is embedded and installed in the center of the condenser lens,
A distance measuring device characterized by: The distance measuring device according to any one of claims 1 to 6,
The condensing lens includes a notch extending from the side edge to the center,
A mirror that reflects the laser beam in the optical axis direction of the condenser lens is disposed at the center of the condenser lens,
The laser beam is incident along the notch from the side of the condensing lens and is reflected by the mirror in the optical axis direction.
A distance measuring device characterized by:

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