Range finding device

Abstract

A range finding device (1) measures the distance to an object by scanning light outward and detecting light reflected by the object, and comprises: a swing shaft (13) that is driven by an actuator (50); a mirror (18) that is driven in a swinging manner by the actuator (50) and scans the light outward; and a holder (21-28). The holder (21-28) has a shaft holding section (31) in which a hole section (311) into which the swing shaft (13) is press-fitted is formed, and a mirror holding section (32, 33) that is formed integrally with the shaft holding section (31) and to which the mirror (18) is attached using an adhesive member (29). A mirror abutting section (41-48) that protrudes toward the mirror (18) side and abuts the mirror (18) is formed in the mirror holding section (32, 33).

Description

distance measuring device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2023-116539, filed on July 18, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a distance measuring device.

[0003] Distance measuring devices have been known that detect the distance to an object by irradiating a transmission wave and detecting the reflected wave from the object. Optical scanning devices are used in distance measuring devices, and the optical scanning device disclosed in Patent Document 1, for example, scans light by rotating a mirror back and forth.

[0004] Japanese Patent Application Laid-Open No. 2021-96295

[0005] In Patent Document 1, a plate-shaped mirror is attached to one surface of a substrate. When using adhesive or double-sided tape to attach the mirror to a holding member such as a substrate, it is difficult to adjust the thickness of the material used for adhesion, and there is a risk that variations in thickness will affect distance measurement accuracy. An object of the present disclosure is to provide a distance measuring device that can suppress variations in the position of the mirror surface.

[0006] The distance measuring device disclosed herein measures the distance to an object by scanning light externally and detecting the light reflected by the object, and is equipped with an oscillating axis driven by an actuator, a mirror that is oscillated by the actuator to scan light externally, and a holder.

[0007] The holder has a shaft holding part in which a hole for press-fitting the oscillating shaft is formed, and a mirror holding part formed integrally with the shaft holding part to which the mirror is attached with an adhesive. The mirror holding part has a mirror abutment part that protrudes toward the mirror and abuts against the mirror. This makes it possible to suppress variations in the position of the mirror surface.

[0008] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a cross-sectional view showing a swing actuator of a distance measuring device according to a first embodiment, Fig. 2 is a perspective view showing a spindle, a holder, and a mirror according to the first embodiment, Fig. 3 is a plan view showing a holder according to the first embodiment, Fig. 4 is a view taken in the direction of arrow IV in Fig. 3, Fig. 5 is an enlarged view of a fourth V portion, Fig. 6 is a plan view showing a holder according to a second embodiment, Fig. 7 is a plan view showing a holder according to a third embodiment, and Fig. 8 is a plan view showing a holder according to a fourth embodiment. 9 is a plan view showing a holder according to the fifth embodiment, FIG. 10 is a view taken in the direction of the arrow X in FIG. 9, FIG. 11 is a plan view showing a holder according to the sixth embodiment, FIG. 12 is a view taken in the direction of the arrow XII in FIG. 11, FIG. 13 is a plan view showing a holder according to the seventh embodiment, FIG. 14 is a view taken in the direction of the arrow XIV in FIG. 13, FIG. 15 is a plan view showing a holder according to the eighth embodiment, FIG. 16 is a view taken in the direction of the arrow XVI in FIG. 15, and FIG. 17 is a schematic diagram showing a distance measuring device according to an embodiment.

[0009] A distance measuring device according to the present disclosure will be described below with reference to the drawings. In the following, substantially identical components in multiple embodiments will be assigned the same reference numerals and descriptions thereof will be omitted.

[0010] 1 to 5 show a first embodiment. FIG. 17 shows a schematic configuration of a distance measuring device. As shown in FIG. 17, the distance measuring device 1 is a LiDAR (Light Detection and Ranging) device that measures the distance to an object by irradiating light and detecting reflected light from the object. The distance measuring device 1 is mounted on, for example, a vehicle and used to detect objects present in front of the vehicle.

[0011] The distance measuring device 1 includes a light emitting unit 91, a light receiving unit 92, and a swing actuator 5, and is housed in a housing 93. The light emitting unit 91 intermittently outputs a light beam B. The output light beam B is reflected by a mirror 18 that is driven to swing, and is emitted to the outside through an optical window 94. The light receiving unit 92 receives light reflected from an object that is irradiated with the light beam B. The light detected by the light receiving unit 92 is converted into an electrical signal, which is used to calculate the distance to the object.

[0012] As shown in Fig. 1, the oscillation actuator 5 includes a mirror unit 10, an oscillation motor 50, and an encoder 60. The mirror unit 10 includes a base 11, a spindle 13, a mirror 18, and a holder 21. The base 11 includes a mounting unit 111 and holding walls 112 and 113, which are integrally formed from, for example, metal. The mounting unit 111 is attached to a housing with bolts or the like. The holding walls 112 and 113 are provided substantially perpendicularly on both ends of the mounting unit 111.

[0013] The spindle 13 is disposed substantially parallel to the mounting portion 111 and is rotatably held on the base 11 by bearings 14 and 15 provided on the retaining walls 112 and 113. In this embodiment, the bearings 14 and 15 are ball bearings, but bearings other than ball bearings may also be used. The spindle 13 is formed to extend to the swing motor 50 and encoder 60. Hereinafter, the axis of the spindle 13 will be referred to as the swing axis Ax, and the swing axis direction will simply be referred to as the "axial direction." Furthermore, in the configuration of the holder 21, etc., the side closer to the swing axis Ax will be referred to as the inner side in the swing direction, and the side farther from it will be referred to as the outer side. The E-ring 16 is provided on the axial outer side of the bearing 14 and functions to prevent the spindle 13 from coming off.

[0014] 1 and 2 , the mirror 18 is formed in a rectangular plate shape in a plan view and is attached to the holder 21 so as to be symmetrical about the oscillation axis Ax. The mirror 18 may have a shape other than rectangular as long as it is symmetrical about the oscillation axis Ax. The holder 21 and the mirror 18 are disposed inside the base 11 so that the mirror surface 181 faces away from the mounting portion 111, and are driven to oscillate by the oscillation motor 50. The mirror 18 reflects the light beam B output from the light-emitting unit 91 on the mirror surface 181 and emits the light beam B to the outside in a direction corresponding to the oscillation position of the mirror 18, thereby scanning the light beam within a predetermined scanning range.

[0015] The holder 21 has a press-fit portion 31 and a mirror holding portion 32, which are integrally formed from, for example, metal. The press-fit portion 31 has a hole 311 through which the spindle 13 is inserted, and the spindle 13 is press-fitted and fixed. The press-fit portion 31 protrudes further from the mirror holding portion 32 on the side opposite the mirror 18. In other words, the plate thickness of the mirror holding portion 32 is smaller than that of the press-fit portion 31.

[0016] The mirror 18 is attached to the mirror holding portion 32 with an adhesive or the like on a mirror mounting surface, which is the surface opposite to the surface from which the press-fit portion 31 protrudes. The mirror holding portions 32 are formed symmetrically on both sides of the press-fit portion 31 with respect to the oscillation axis Ax. This allows the moment of inertia during oscillation to be equalized in both directions. The axial length of the mirror holding portion 32 is longer than that of the press-fit portion 31, and the holder 21 as a whole is formed into a generally H-shape in a plan view. By making the axial length of the press-fit portion 31 shorter than that of the mirror holding portion 32, the holder 21 can be made lighter while ensuring a mounting area for the mirror 18. Details of mounting the mirror 18 to the holder 21 will be described later.

[0017] 1, the oscillation motor 50 is provided on one axial side of the mirror unit 10. The oscillation motor 50 includes a stator 51, a rotor magnet 52, and a preload spring 54. The stator 51 is fixed to the retaining wall 113 with bolts or the like. The stator 51 is provided with an electromagnetic coil and a fixed magnet (not shown).

[0018] The rotor magnet 52 is formed in a cylindrical shape with an axial hole 521 provided at the center, is inserted into the spindle 13, and is fixed to the spindle 13 by a rotor fixing member 53. One end of the preload spring 54 abuts against the bearing 15, and the other end abuts against the rotor magnet 52.

[0019] The rotor magnet 52 is disposed inside the stator 51 and oscillates around a stationary position when current is applied to the electromagnetic coil. Here, "oscillation" refers to a motion in which the rotor magnet 52 periodically rotates back and forth within a predetermined angular range less than 360°. When current is turned off to the electromagnetic coil, the rotor magnet 52 returns to the stationary position due to the magnetic force of the fixed magnet and remains stationary.

[0020] The encoder 60 has a disk 61 and a detection element 63, and is housed in a case 65. The disk 61 is attached to a disk hub (not shown) that is press-fitted and fixed on the encoder 60 side of the spindle 13, and rotates integrally with the spindle 13. The detection element 63 is mounted on a substrate 64, and detects the rotational position of the disk 61. This allows the encoder 60 to detect the oscillation positions of the oscillation motor 50 and the mirror 18. A through-hole 641 is formed in the substrate 64, and the spindle 13 is inserted through it.

[0021] In this embodiment, the mirror 18 is attached to the holder 21 using an adhesive member 29 (see FIG. 5 ), which is an adhesive, double-sided tape, or the like. When the mirror 18 is attached using the adhesive member 29, it is difficult to adjust the thickness of the adhesive member 29, and therefore there is a risk that the distance between the mirror surface 181 and the spindle 13 will vary.

[0022] Furthermore, when the spindle 13 is press-fitted into the hole 311 of the holder 21, the press-fit portion 31 may bulge toward the mirror 18. If the holder 21 bulges due to the press-fitting, the surface precision of the mirror mounting surface may deteriorate, which may cause variations in the distance between the mirror surface 181 and the spindle 13. Variations in the distance between the mirror surface 181 and the spindle 13 affect the distance measurement accuracy.

[0023] Therefore, in this embodiment, as shown in FIGS. 3 to 5 , a mirror contact portion 41 that contacts the mirror 18 at its tip end is formed on the surface of the holder 21 facing the mirror 18. In this embodiment, the mirror contact portion 41 is formed to extend axially along the end of the mirror holding portion 32 facing the press-fit portion 31. The protruding height of the mirror contact portion 41 is set to a height (e.g., approximately 0.1 mm) that ensures the necessary mounting strength when attaching the mirror with the adhesive member 29. The adhesive member 29 is provided outside the mirror contact portion 41, and the mirror 18 is attached to it. The mirror contact portion 41 contacts the mirror 18, thereby restricting the thickness of the adhesive member 29. Note that in FIG. 5 , the adhesive member 29 is shown with a matte finish for ease of explanation. This is also true in FIG. 10 and other figures.

[0024] Furthermore, by forming the mirror abutment portion 41 at the end on the press-fit portion 31 side, the mirror abutment portion 41 functions as a restricting wall that prevents the adhesive material 29 from flowing out toward the press-fit portion 31. The holder 21 and the mirror 18 abut against each other at the mirror abutment portion 41, and the mirror 18 and the holder 21 are bonded together at the mirror holding portion 32 provided on the outside of the press-fit portion 31, thereby forming a gap between the press-fit portion 31 and the mirror 18. As a result, even if the press-fit portion 31 is deformed by the press-fitting of the spindle 13, the expansion is absorbed by the gap, so the press-fit portion 31 does not interfere with the mirror 18. This makes it possible to suppress variations in the distance between the mirror surface 181 and the spindle 13, ensuring distance measurement accuracy.

[0025] As described above, the distance measuring device 1 measures the distance to an object by scanning light externally and detecting the light reflected by the object, and is equipped with a spindle 13 driven by an oscillating motor 50, a mirror 18 that is driven to oscillate by the oscillating motor 50 and scans light externally, and a holder 21.

[0026] The holder 21 has a press-fit portion 31 in which a hole 311 into which the spindle 13 is press-fitted is formed, and a mirror holding portion 32 formed integrally with the press-fit portion 31 and to which the mirror 18 is attached with an adhesive member 29. The mirror holding portion 32 has a mirror abutment portion 41 formed thereon that protrudes toward the mirror 18 and abuts against the mirror 18.

[0027] In this embodiment, a protruding mirror abutment portion 41 is formed on the mirror mounting surface of the mirror holding portion 32, and the holder 21 and the mirror 18 are abutted at the mirror abutment portion 41 without the adhesive member 29, thereby suppressing variations in the distance between the mirror surface 181 and the oscillation axis Ax. Furthermore, by providing the mirror abutment portion 41 at a location other than the press-fit portion 31, it is possible to prevent deterioration in the surface accuracy of the mirror surface 181 due to deformation of the press-fit portion 31 caused by press-fitting the spindle 13. This ensures the positional accuracy of the mirror surface and improves distance measurement accuracy.

[0028] The press-fit portion 31 and the mirror holding portion 32 are separated by a mirror contact portion 41. The mirror 18 is attached to the holder 21 by an adhesive member 29 provided on the mirror holding portion 32, and is spaced apart from the press-fit portion 31. Because the adhesive member 29 is not provided on the press-fit portion 31, there is no need to consider the effect of the thickness of the adhesive member 29, and the press-fit portion 31 does not interfere with the mirror 18 even after press-fitting. This further improves the distance measurement accuracy.

[0029] The length of the mirror holding portion 32 in the direction of the swing axis (i.e., for example, the vertical direction on the paper in FIG. 3) is greater than that of the press-fit portion 31. This makes it possible to ensure a sufficient adhesion area with the mirror 18 regardless of the press-fit length.

[0030] Second Embodiment A second embodiment is shown in FIG. 6. The second to eighth embodiments differ in the shape of the holder, and this will be mainly described. The mirror holding portion 32 of the holder 22 has a mirror contact portion 41 formed on the press-fit portion 31 side, as well as a mirror contact portion 42 on the outer side in the swing direction. An adhesive member 29 is provided between the mirror contact portions 41, 42, and the mirror 18 (not shown in FIG. 6, etc.) is attached to the holder 22. The mirror contact portions 41, 42 are formed at the same height and contact the mirror 18 at their tip surfaces. By forming the mirror contact portion 42 on the outer side, deformation of the mirror 18 due to swing can be suppressed. Furthermore, protrusion of the adhesive member 29 to the outer side can be prevented. The same effects as the above-described embodiments can be achieved.

[0031] Third Embodiment A third embodiment is shown in FIG. 7 . A mirror abutment portion 43 is provided on the mirror holding portion 32 of the holder 23. The mirror abutment portion 43 is formed along the outer edge of the mirror holding portion 32. An adhesive member 29 is provided in the inner area surrounded by the mirror abutment portion 43, and the mirror 18 is attached to the holder 23. The holder 23 abuts against the mirror 18 at the tip surface of the mirror abutment portion 43. By providing the mirror abutment portion 43 along the outer edge of the mirror holding portion 32, deformation of the mirror 18 due to swinging can be suppressed. Furthermore, protrusion of the adhesive member 29 can be prevented.

[0032] An opening 435 is formed in the mirror contact portion 43. In this embodiment, the opening 435 is formed on the press-fit portion 31 side and functions as an air vent during bonding and as a relief portion when the adhesive member 29 expands due to heat or the like. This makes it possible to suppress a decrease in distance measurement accuracy due to temperature changes or the like. In addition, the same effects as those of the above embodiment are achieved.

[0033] (Fourth Embodiment) A fourth embodiment is shown in FIG. 8 . A mirror abutment portion 44 is provided on the mirror holding portion 32 of the holder 24. The mirror abutment portion 44 is formed along the end of the mirror holding portion 32 on the press-fit portion 31 side and both axial ends, and is open to the outside. The adhesive member 29 is provided in the area surrounded by the mirror abutment portion 44, and the mirror 18 is attached to the holder 24. This prevents the adhesive member 29 from flowing into the press-fit portion 31 side. It also makes it possible to suppress deformation of the mirror 18 due to rocking. Furthermore, the same effects as those of the above-mentioned embodiments are achieved.

[0034] 9 and 10 show a fifth embodiment. The holder 25 has a press-fit portion 31 and a mirror holding portion 33 integrally formed therein. The mirror holding portion 33 is formed to have a generally rectangular shape in a plan view. The press-fit portion 31 protrudes beyond the mirror holding portion 33 on the side opposite the mirror 18. As in the above embodiments, the axial length of the press-fit portion 31 is shorter than that of the mirror holding portion 33. A groove 312 is formed on the surface of the mirror holding portion 33 opposite the mirror 18 to prevent interference with the spindle 13 inserted through the hole 311.

[0035] A mirror abutment portion 45 is formed to protrude from the surface of the holder 25 facing the mirror 18. The mirror abutment portion 45 is formed on the mirror mounting surface, extending in the axial direction along the outer side of the projection area of ​​the press-fit portion 31 in the swing direction. An adhesive member 29 is provided on the outer side of the mirror abutment portion 45, and the mirror 18 is attached to the holder 25. The mirror 18 abuts against the holder 25 at the tip surface of the mirror abutment portion 45. In this embodiment, the mirror 18 and the mirror holding portion 33 are spaced apart in the area where the press-fit portion 31 is formed. This configuration also achieves the same effects as the above embodiment.

[0036] Sixth Embodiment A sixth embodiment is shown in Figures 11 and 12. In the sixth embodiment, mirror contact portions 46 are formed to protrude from the holder 26 on the outer side in the swing direction of the mirror mounting surface of the mirror holding portion 33. An adhesive member 29 is provided in an area sandwiched between the mirror contact portions 46, and the mirror 18 is attached to the holder 26. The mirror 18 contacts the holder 26 at the tip end surfaces of the mirror contact portions 46. By providing the mirror contact portions 46 on the outer side in the swing direction, deformation of the mirror 18 due to swing can be suppressed. In addition, the same effects as those of the above-mentioned embodiments can be achieved.

[0037] Seventh Embodiment As shown in FIGS. 13 and 14 , the mirror contact portions 47 of the holder 27 of the seventh embodiment are formed to protrude from the mirror mounting surface of the mirror holding portion 33. The mirror contact portions 47 are formed along both axial ends (the upper and lower ends of the paper in FIG. 13 ) and at four locations outside the swing direction of the region where the press-fit portion 31 extends in the axial direction. An adhesive member 29 is provided in the region on the mirror mounting surface where the mirror contact portions 47 are not formed, and the mirror 18 is attached to the holder 27. The mirror 18 abuts against the holder 27 at the tip end surfaces of the mirror contact portions 47. By forming the mirror contact portions 47 on the axially outer side, deformation of the mirror 18 due to vibrations caused by swing can be suppressed. This embodiment also achieves the same effects as the above-described embodiments.

[0038] Eighth Embodiment As shown in Figures 15 and 16, the mirror abutment portion 48 of the holder 28 in the eighth embodiment is formed outside the rocking direction of the portion where the press-fit portion 31 is formed, protruding from an intermediate region in the axial direction. An adhesive member 29 is provided in an area on the mirror mounting surface where the mirror abutment portion 48 is not formed, and the mirror 18 is attached to the holder 28. The mirror 18 abuts against the holder 28 at the tip surface of the mirror abutment portion 48. This configuration also achieves the same effects as the above-described embodiments. Note that the adhesive member 29 is omitted from Figure 16 to avoid complexity.

[0039] In the embodiment, the spindle 13 corresponds to the "swing shaft," the press-fit portion 31 corresponds to the "shaft holding portion," and the swing motor 50 corresponds to the "actuator."

[0040] In the above embodiment, the mirror contact portions are formed at two or four locations on the mirror mounting surface of the holder. In other embodiments, the shape and number of the mirror contact portions may be different from those in the above embodiment.

[0041] In the above embodiment, the press-fit portion is formed to protrude on the side opposite the mirror mounting surface. In other embodiments, the shape of the press-fit portion may be any. For example, depending on the spindle diameter and the holder thickness, the press-fit portion may not protrude, and the press-fit hole may be formed to penetrate the holder interior. In such a case, the area obtained by projecting the press-fit hole in a direction perpendicular to the oscillation axis is considered to be the "shaft holding portion," and the area outside the shaft holding portion is considered to be the "mirror holding portion," and the mirror abutment portion may be formed at any location on the mirror holding portion.

[0042] The shapes of the holder and mirror may be different from those of the above embodiment. It is desirable that the holder and mirror be symmetrical with respect to the oscillation axis in order to equalize the moment of inertia during oscillation. Furthermore, the configuration and arrangement of the oscillation motor and mirror unit may be different from those of the above embodiment, as long as they are capable of oscillating the mirror.

[0043] As described above, the present disclosure is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the present disclosure.

[0044] The present disclosure has been described based on the embodiments. However, the present disclosure is not limited to the embodiments and structures. The present disclosure also encompasses various modifications and variations within the scope of equivalents. Furthermore, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A distance measuring device that measures the distance to an object by scanning light outward and detecting the light reflected by the object, comprising: an oscillating shaft (13) driven by an actuator (50); a mirror (18) that is oscillated by the actuator to scan light outward; and a holder (21-28) having an axis holding portion (31) in which a hole portion (311) into which the oscillating shaft is pressed, and a mirror holding portion (32, 33) that is formed integrally with the axis holding portion and to which the mirror is affixed with an adhesive member (29), wherein the mirror holding portion has a mirror abutment portion (41-48) that protrudes toward the mirror and abuts against the mirror.

2. A distance measuring device as described in claim 1, wherein the axis holding portion and the mirror holding portion are separated by the mirror abutment portion (41, 44, 45), and the mirror is attached to the holder by the adhesive material provided on the mirror holding portion and is spaced apart from the axis holding portion.

3. A distance measuring device according to claim 1 or 2, wherein the length of said mirror holding portion in the direction of the swing axis is greater than that of said shaft holding portion.

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