JP2016033482A - Laser range finer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser range finer capable of preventing malfunction from being occurred.SOLUTION: A laser range finder 1 includes: a housing 11; a light source 10 arranged in the housing 11, and emitting laser light; a scan mirror 20 scanning the laser light from the light source 10 in a mirror scan area; a reflection plate 52 arranged in the mirror scan area and the housing 11, and reflecting the laser light from the scan mirror 20; a light shading member 51 arranged in a range finding area out of the mirror scan area and in the housing 11, and limiting intensity of the laser light from the scan mirror 20 to transmit the laser light to the outside of the housing 11; a light reception unit 30 receiving reflected light from an object and the reflection plate 52 of the laser light scanned by the scan mirror 20; and a signal processing unit 60 calculating a direction of the object to the laser range finer 1 by using timing when the light reception unit 30 receives the reflected light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser range finder for measuring a distance to an object.

  As a sensor for detecting an obstacle when the robot moves autonomously, or a sensor for detecting a person, for example, there is a laser range finder (LRF). The laser range finder measures the time from when the laser light is emitted until the reflected light that is reflected when the laser light hits the object and returns, and calculates the distance to the object from the measurement result.

  Specifically, the laser range finder receives, for example, a laser diode (Laser Diode, LD) that emits laser light, an oscillating mirror that adjusts the emission direction of the laser light, and light that is reflected from an object. The device includes a signal processing unit that measures the distance to the object from the difference between the phase of the laser light emitted from the laser diode and the phase of the reflected light received by the light receiving device.

  In addition, a shape measuring apparatus that measures the shape of an object using such a laser range finder has been proposed (see, for example, Patent Document 1). This shape measuring apparatus can estimate the shape of an object by determining the direction of the object as follows. Specifically, a reference reflector that reflects the laser beam is provided on a part of the scan orbit of the laser beam used for distance measurement, and the timing at which the light receiving unit receives the laser beam reflected by the reference reflector. By using it, the direction of the object with respect to the laser range finder is obtained.

JP 2013-160545 A

  However, when a laser range finder is configured using a coaxial optical system, the reflected light from the object and the reflected light from the reference reflector may not be distinguished. For example, when the object has the same reflectance as the reference reflector, or when the object of the total reflector is stuck to the opening for emitting laser light of the laser range finder housing, Since the light intensity of the reflected light from the object and the reflected light from the reference reflecting plate are equal, the reflected light may not be distinguished.

  As described above, when it is not possible to distinguish which reflected light, it is difficult to determine whether or not the emission direction of the laser light is the reference position where the reference reflector is provided. If the determination is wrong, there may be an error in angle recognition (direction recognition) of the object and an unexpected calibration operation. That is, in such a case, the laser range finder may malfunction.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a laser range finder that can prevent malfunction.

  In order to achieve the above object, a laser range finder according to one aspect of the present invention is a laser range finder that measures a distance to an object, and is disposed within a housing and the housing to emit laser light. A scanning light source, a oscillating mirror that scans laser light from the light source in a scanning region, a reflector that is disposed in the scanning region and the housing and reflects the laser light from the oscillating mirror, and the scanning region The optical path of the laser light reaching the reflector from the oscillating mirror and the ranging area excluding the extension of the optical path, and the intensity of the laser light from the oscillating mirror disposed in the housing A light limiting member that restricts and transmits to the outside of the housing, a light receiving unit that receives reflected light from the object and the reflection plate of the laser beam scanned by the swing mirror, and the light receiving unit includes the reflected light Receive light By using the timing and a signal processing unit for calculating the direction of the object relative to the laser range finder.

  As a result, the light intensity of the laser light output to the distance measuring area outside the housing is smaller than the light intensity of the laser light output to the distance measuring area inside the housing. That is, even when the object is a total reflection target, the light intensity of the reflected light from the object is necessarily smaller than the light intensity from the reflector disposed inside the housing. Therefore, the laser range finder can identify whether the light received by the light receiving unit is reflected light from the object or reflected light from the reflecting plate. In other words, the reflected light from the distance measuring area and the reflected light from the reflecting plate can be distinguished. That is, the distance measurement area and the reference position where the reflector is disposed can be separated and identified with high accuracy. Accordingly, since it is possible to suppress erroneous recognition of reflected light from the distance measurement area as reflected light from the reference position, for example, an error in angle recognition (direction recognition) of an object, which may occur due to the erroneous recognition, and unexpectedness. Malfunction of the laser range finder such as a simple calibration operation can be reduced.

  For example, the light limiting member is provided in the opening of the casing, and limits the intensity of the laser light by shielding part of the spot in the opening of the laser light from the oscillating mirror. And a light shielding member that transmits to the outside of the housing.

  In this way, by providing a light shielding member that blocks a part of the laser beam spot, the laser beam intensity output to the distance measuring area outside the casing is output to the distance measuring area inside the casing. It can be made smaller than the light intensity of light. On the other hand, the light shielding member has a width smaller than the laser spot diameter in the opening, and occupies a very small area compared to the area of the oscillating mirror and the opening area of the opening. Therefore, the light shielding member does not limit the opening area necessary for accurately measuring the distance by using the reflected light from the object which is diffused light having a very low light intensity. Therefore, it is possible to suppress the influence of the light amount reduction due to the provision of the light blocking member when the reflected light from the object passes through the opening. As a result, the S / N ratio at the light receiving portion can be handled in the same manner as when there is no light shielding member. That is, the accuracy of ranging is improved by improving the angle recognition accuracy.

  Further, for example, the light shielding member may be disposed in the distance measuring area along the scanning direction of the laser beam by the oscillating mirror.

  Thereby, the light shielding member can shield the laser beam from the oscillating mirror at an equal ratio at any position in the scanning direction of the laser beam by the oscillating mirror. Therefore, the distance measurement area and the reference position can be separated and identified with higher accuracy.

  Further, for example, the light limiting member may be a neutral density filter that is provided at an opening of the casing and limits the intensity of the laser light and transmits the laser beam to the outside of the casing.

  Thereby, when assembling a laser range finder, it becomes difficult to require high accuracy for positioning the light limiting member and the oscillating mirror. In other words, the assembly of the laser range finder can be facilitated. Further, even when the oscillating mirror scans the laser beam two-dimensionally, the malfunction of the laser range finder can be reduced.

  Further, for example, the reflection plate may be disposed at an end of the scanning region.

  Thereby, the reflected light from the reflecting plate can be received at a constant time interval, so that the maximum scanning angle of the oscillating mirror can be easily calculated. Therefore, the direction of the object can be easily calculated.

  Further, for example, the oscillating mirror oscillates about at least two axes including a predetermined axis, and the reflecting plate closes the opening of the housing in a direction parallel to the predetermined axis. It may be arranged.

  Thereby, the difference between the intensity of the reflected light from the distance measuring area and the intensity of the reflected light from the reflecting plate is small, so that the reference position where the ranging area and the reflecting plate are arranged based on the intensity of the reflected light. Even if it is difficult to separately identify the distance measurement area, it is possible to identify the distance measurement area and the reference position where the reflection plate is disposed based on the timing of receiving the reflected light. Specifically, since it is unlikely that there is high reflection with a certain width in a direction parallel to the predetermined axis of the distance measurement area, reflected light that appears at a certain period and with a certain intensity is reflected from the reference position. It can be regarded as reflected light. Thus, the distance measurement region and the reference position can be separated and identified by regarding the reflected light that appears at a constant cycle and a constant intensity as reflected light from the reference position. Therefore, even when the difference between the intensity of the reflected light from the distance measuring area and the intensity of the reflected light from the reflecting plate is small, the distance measuring area and the reference position can be separated and identified with high accuracy. .

  According to the present invention, it is possible to prevent malfunction.

It is a perspective view which shows an example of schematic structure of the laser range finder in embodiment. It is a block diagram which shows an example of a function structure of the signal processing part of the laser range finder in embodiment. It is a perspective view which shows an example of a structure of the window part in embodiment. It is sectional drawing which shows the mode of the light which passes the ranging area of the window part in embodiment. It is sectional drawing which shows the mode of the light in the reference position detection area of the window part in embodiment. It is a perspective view which shows an example of a structure of the window part in a comparative example. It is a figure for demonstrating the problem which arises in a comparative example. In a comparative example, it is a graph which shows the various signals acquired in a signal processing part in the case of the state of Drawing 7, (a) is a graph which shows received light amplitude intensity, and (b) is a graph which shows a reference position detection signal. is there. It is a figure for demonstrating the effect which arises in embodiment. 9 is a graph showing various signals acquired by the signal processing unit in the state of FIG. 9, (a) is a graph showing the received light intensity, and (b) is a graph showing the reference position detection signal. It is. It is a perspective view which shows an example of a structure of the window part in the modification 1 of embodiment. It is a perspective view which shows an example of a structure of the window part in the modification 2 of embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connecting forms of the constituent elements shown in the following embodiments are merely examples, and are not intended to limit the present invention. The invention is specified by the claims. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims are not necessarily required to achieve the object of the present invention, but are described as constituting more preferable embodiments. Is done.

(Embodiment)
[1. Configuration of laser range finder]
First, the configuration of the laser range finder according to the present embodiment will be described with reference to FIGS.

  FIG. 1 is a perspective view showing an example of a schematic configuration of a laser range finder 1 in the embodiment. FIG. 1 is a view showing the inside of the housing 11 through the housing 11 of the laser range finder 1. Further, for the convenience of explanation, the light shielding member 51 and the reflection plate 52 are shaded. FIG. 2 is a block diagram illustrating an example of a functional configuration of the signal processing unit 60 of the laser range finder 1 according to the embodiment. In addition to the signal processing unit 60, the light receiving unit 30 is also illustrated in FIG.

  In FIG. 1, the Z-axis direction is shown as an axis parallel to the scanning axis (reference direction) of the laser range finder 1, and the Y-axis is shown as the vertical direction (direction in which gravity acts in the installed state). . In the following description, the Y-axis direction is assumed to be the vertical direction. However, depending on the usage, the Y-axis direction may not be the vertical direction, so the Y-axis direction is not limited to the vertical direction. The same applies to the following drawings.

  In the following, for example, the X axis direction plus side indicates the arrow direction side of the X axis, and the X axis direction minus side indicates the opposite side to the X axis direction plus side. The same applies to the Y-axis direction and the Z-axis direction.

  As shown in FIG. 1, the laser range finder 1 in the present embodiment includes a light source 10, a scan mirror 20, and a light receiving unit 30 (the light receiving unit 30 includes an optical unit that collects reflected light from the scan mirror 20. 2), a beam splitter 40, a window 50, and a signal processor 60 shown in FIG.

  The light source 10 is disposed in the housing 11, emits laser light, and is configured by, for example, a laser diode (LD). The light source 10 emits laser light in accordance with a modulation signal output from a modulation signal output unit (not shown).

  The scan mirror 20 is a oscillating mirror that scans the laser light from the light source 10 in a scanning region (A-C area in the figure). For example, the scan mirror 20 is oscillated around a predetermined axis by an oscillator (not shown). It is a moving MEMS (Micro Electro Mechanical System) mirror. Note that the axis extends, for example, in the Y-axis direction. The scan mirror 20 has a function of scanning the laser light from the light source 10 in one axial direction (for example, in the horizontal direction) toward the object by swinging about the axis. Further, the scan mirror 20 has a function of reflecting the laser beam reflected by the object toward the light receiving unit 30.

  Here, the laser light emitted from the light source 10 is scanned in a predetermined range (A-C area in FIG. 1) when the scan mirror 20 is swung. A reflection plate 52 (described later) is provided in a part of the predetermined range (B-C area in FIG. 1), and laser light incident on the reflection plate 52 from the scan mirror 20 is reflected by the laser range finder 1. Is reflected to the scan mirror 20 without being emitted to the outside. That is, of the laser light scanned by the scan mirror 20, the laser light emitted to the outside of the laser range finder 1 is emitted to the other part of the predetermined range (A-B area in FIG. 1). Light. Hereinafter, the A-C area in FIG. 1 may be referred to as a mirror scan area (scanning area), the A-B area as a ranging area (ranging area), and the B-C area as a reference position detection area.

  In other words, the distance measurement area (AB area) is a mirror scan area (AC area) in which laser light is scanned by the scan mirror 20, and the laser range finder 1 detects the distance and direction of the object. It is an area where you can. That is, the distance measuring area (A-B area) is an area excluding the optical path of the laser light reaching the reflecting plate 52 from the scan mirror 20 and the extension of the optical path in the mirror scan area (AC area). It is.

  The reference position detection area (BC area) refers to the laser light that reaches the reflector 52 from the scan mirror 20 in the mirror scan area (AC area) in which the laser light is scanned by the scan mirror 20. It is a region formed by an optical path and an extension of the optical path.

  In the present embodiment, since the scan mirror 20 scans the laser light L1 in one axis direction (horizontal direction) as described above, the mirror scan area, the distance measurement area, and the reference position detection area are two-dimensional planar areas. It becomes.

  In the present embodiment, the scan mirror 20 is described as scanning laser light in one axis direction (for example, the horizontal direction), but the scan mirror 20 scans laser light in two axis directions (the horizontal direction and the vertical direction). In this case, the mirror scan area, the distance measurement area, and the reference position detection area are three-dimensional spatial areas.

  The light receiving unit 30 receives a laser beam object scanned by the scan mirror 20 and reflected light from the reflection plate 52, for example, a photodiode (PD) or an avalanche having higher sensitivity than the photodiode. It is composed of a photodiode (APD: Avalanche Photo Diode). Specifically, the light receiving unit 30 receives the reflected light from the object and the reflection plate 52 via the scan mirror 20 and the beam splitter 40. The light receiving unit 30 is disposed on the optical path of the reflected light from the object and the reflecting plate 52, and collects the reflected light that has passed through the scan mirror 20 and the beam splitter 40 and guides it to the PD (for example, a collecting unit). Optical lens).

  The beam splitter 40 is disposed between the light source 10 and the scan mirror 20, passes the laser light emitted from the light source 10 as it is, and reflects (leads) the light from the scan mirror 20 to the light receiving unit 30. The beam splitter 40 may be used as long as it is a member that passes the laser light emitted from the light source 10 as it is and reflects the light from the scan mirror 20, and may be a perforated mirror, for example.

  The window 50 is provided in the opening of the housing 11 and includes a light shielding member 51 and a reflecting plate 52. The laser light reflected by the scan mirror 20 is emitted to the outside of the housing 11 (outside of the laser range finder 1) through the window 50. Further, the reflected light from the object of the emitted laser light is incident on the inside of the housing 11 (inside the laser range finder 1) through the window portion 50. Details of the window 50 will be described later.

  Here, the laser light reflected by the scan mirror 20 is linearly polarized light having a relatively large light intensity. On the other hand, the reflected light from the object is diffused light having a very small light intensity. Therefore, the area other than the area where the light shielding member 51 and the reflecting plate 52 are provided in the opening of the housing 11 is larger than the area of the scan mirror 20 and has a sufficient amount of light to receive the reflected light from the object by the light receiving unit 30. It is preferable to make it as large as possible.

  In the following description of the present embodiment, it is assumed that the reflecting plate 52 is provided in the window 50, but the present invention is not limited to this. The reflection plate 52 only needs to be provided in the mirror scan area (scanning region). For example, when the end of the scanning region includes the opening end of the housing 11, the reflection plate 52 opens the inner surface of the housing 11. It may be provided at the end.

  Next, the functional configuration of the signal processing unit 60 of the laser range finder 1 in the embodiment will be described with reference to FIG.

  The signal processing unit 60 shown in the figure calculates the distance from the laser range finder 1 to the target object using the reflected light from the target object received by the light receiving unit 30. Further, the direction (angle) of the object is calculated using the reflected light from the reflecting plate 52 received by the light receiving unit 30. The signal processing unit 60 includes a ranging signal processing unit 61, an intensity signal monitoring unit 62, a reference position detection unit 63, and a calculation unit 64. For example, a system LSI (Large Scale Integration) is provided. Alternatively, it is configured using an IC (Integrated Circuit). Alternatively, the signal processing unit 60 may be configured by a microcontroller. Hereinafter, a specific configuration of the signal processing unit 60 will be described.

  The ranging signal processing unit 61 uses the phase difference between the modulation signal included in the laser light emitted from the light source 10 and the modulation signal included in the reflected light received by the light receiving unit 30 from the laser range finder 1. Calculate the distance to the object. That is, the ranging signal processing unit 61 uses the phase difference to calculate the time from when the laser light is emitted from the light source 10 until it is received by the light receiving unit 30. This time is the time required for the laser light to reciprocate from the light source 10 to the measurement object. Therefore, the ranging signal processing unit 61 can obtain the distance by multiplying 1/2 of the time by the speed of light. Further, the ranging signal processing unit 61 outputs a distance information signal indicating the obtained distance.

  The intensity signal monitor unit 62 determines whether the reflected light is reflected light from the reference position detection area using the light intensity of the reflected light received by the light receiving unit 30. Specifically, when the light intensity of the reflected light is equal to or greater than a predetermined threshold (for example, the saturated light amount of the reflected light from the distance measuring area), the reflected light is reflected from the reference position detection area (reflecting plate 52). The clock signal (pulse signal) indicating that the reflected light is reflected light from the reference position detection area is output.

  The reference position detection unit 63 outputs a mirror position recognition signal indicating the scanning direction (scanning angle: scanning position) of the scan mirror 20 using the signal period of the clock signal output from the intensity signal monitoring unit 62. Specifically, the reference position detection unit 63 includes the signal period of the clock signal output from the intensity signal monitor unit 62, the direction in which the reflection plate 52 is disposed with respect to the scan mirror 20, and the direction of the reference position detection area. From this, the maximum scanning angle of the scan mirror 20 is calculated. Furthermore, the scanning direction (scanning angle: scanning position) of the scan mirror 20 is calculated from the calculated maximum scanning angle and the oscillation cycle of the scan mirror 20.

  The calculation unit 64 uses the distance information signal output from the distance measurement signal processing unit 61 and the mirror position recognition signal output from the reference position detection unit 63, and the direction (position) of the object with respect to the laser range finder 1. And the distance from the laser range finder 1 to the object is calculated. Also, scan area distance information indicating the calculated direction and the distance is output.

  Thus, the signal processing unit 60 uses the timing of the reflected light from the reflecting plate 52 received by the light receiving unit 30 and the reflected light from the object, and the direction (position) of the object with respect to the laser range finder 1. Is calculated. Further, the signal processing unit 60 further uses the phase difference between the phase of the reflected light from the object received by the light receiving unit 30 and the phase of the laser light emitted from the light source 10, from the laser range finder 1. Calculate the distance to the object.

  The signal processing unit 60 feeds back a signal indicating the maximum scanning angle of the scan mirror 20 calculated by the reference position detection unit 63 to a mirror driving unit (not shown) that drives (swings) the scan mirror 20. Thus, the maximum scanning angle of the scan mirror 20 may be controlled.

[2. Window configuration]
Next, the structure of the window part 50 is demonstrated using FIG. FIG. 3 is a perspective view showing an example of the configuration of the window 50 in the present embodiment. For convenience of explanation, the light shielding member 51 and the reflection plate 52 are shaded.

  As described above, the window 50 is provided in the opening of the housing 11 and includes the light shielding member 51 and the reflection plate 52. Further, as shown in FIG. 3, a transmissive member 53 is further provided.

[2-1. Shading member]
The light shielding member 51 is disposed in the distance measuring area (AB area) in the mirror scan area (AC area) and in the housing 11, and the intensity (light intensity) of the laser light L <b> 1 from the scan mirror 20. ) Is an example of a light limiting member that transmits to the outside of the housing 11. Here, “arranged in the housing 11” includes both the case of being disposed inside (inward) the housing 11 and the case of being disposed in the opening of the housing 11.

  Specifically, the light shielding member 51 is provided in the opening of the housing 11 and shields a part of the laser spot LS spot in the opening of the laser light L1 from the scan mirror 20, thereby The strength is limited and the light passes through the outside of the housing 11. More specifically, the light shielding member 51 is disposed in the distance measuring area (A-B area) along the scanning direction (horizontal direction) of the laser light L1 by the scan mirror 20. The light shielding member 51 configured in this manner causes the laser beam L1 from the scan mirror 20 to be emitted outside the housing 11 with its intensity (light intensity) being limited. That is, the light shielding member 51 is disposed so as to overlap with a part of the laser spot LS of the laser light L1, thereby transmitting a part of the laser light L1 from the scan mirror 20 as the laser light L2, and the other part. Does not pass through. Here, “does not transmit laser light” is not limited to the case where the transmission amount is zero, but may be that the transmission amount is substantially zero (for example, within 5% of the transmission amount).

  The light shielding member 51 is, for example, a resin containing a light absorber such as carbon black applied to the transmission member 53 and does not transmit the laser light incident on the light shielding member 51. The configuration of the light shielding member 51 is not limited to this, and the laser light may not be transmitted to the outside of the housing 11 by changing the optical path of the laser light incident on the light shielding member 51. It may be a reflecting member such as a mirror that does not transmit light out of the housing 11 and reflects the light path so as not to reach the light receiving unit 30.

  Further, the light shielding member 51 is arranged over the entire distance measuring area (A-B area) along the scanning direction (horizontal direction) of the laser light L1 by the scan mirror 20, and any position in the scanning direction. In this case, it is preferable that the spot area of the laser beam incident on the opening is shielded at an equal ratio. As a result, the laser light from the scan mirror 20 is emitted at the same rate in any optical path of the distance measuring area and emitted outside the housing 11.

  As described above, the light shielding member 51 is disposed on the optical path of the laser light L1 in a part of the scanning angle range of the laser light L1 by the scan mirror 20, and transmits the light by limiting the intensity of the laser light L1 passing through the optical path. To do.

[2-2. reflector]
The reflection plate 52 is disposed in the housing 11 in the mirror scan area (AC area), and reflects the laser light from the scan mirror 20. That is, the reflecting plate 52 is arranged in the housing 11 out of the measurement area (BC area) and in the mirror scan area (AC area). Specifically, the reflection plate 52 has a reflection surface that reflects the laser light L <b> 1 from the scan mirror 20 to the scan mirror 20. The reflection surface only needs to have a relatively large known reflectivity, and may be formed by applying a paint such as white, or a member that totally reflects light like a mirror is attached. And may be configured. In addition, the size of the reflecting surface may be larger than the laser spot LS.

  As described above, the reflection plate 52 is disposed on the optical path of the laser beam L1 in the other part of the scanning angle range of the laser beam L1 by the scan mirror 20, and reflects the laser beam L1 passing through the optical path to the scan mirror 20. To do.

[2-3. Transparent member]
The transmission member 53 is provided so as to close the opening of the housing 11 and transmits the laser light L1 from the scan mirror 20 and the reflected light from the object of the laser light L1, for example, acrylic resin or glass. . Note that the window portion 50 may not include the transmission member 53, and is provided, for example, in a columnar light shielding member 51 that is bridged to the opening portion of the housing 11 and the opening portion of the housing 11. A reflection plate 52 may be provided.

[3. Separation of ranging area and reference position detection area]
With the window 50 configured as described above, the laser range finder 1 according to the present embodiment separates the distance measurement area (AB area) and the reference position detection area (BC area). Can be identified. That is, the reflected light from the reference position detection area can be distinguished from the reflected light from the ranging area.

[3-1. When the object is positioned other than just before the window]
First, a case where the object is located other than immediately before the window 50 will be described with reference to FIGS. 4 and 5. That is, in this case, the object is disposed at a position away from the window 50 by a predetermined distance without sticking to the window 50. FIG. 4 is a cross-sectional view showing the state of light passing through the distance measuring area (A-B area) of the window 50 in the present embodiment. FIG. 5 is a cross-sectional view showing the state of light in the reference position detection area (BC area) of the window 50 in the present embodiment.

[3-1-1. Ranging area]
As shown in FIG. 4, in the distance measurement area (A-B area), the laser beam L1 scanned by the scan mirror 20 has a spot diameter due to the light shielding member 51 in the window 50 (opening of the housing 11). Squeezed. That is, a part of the spot of the laser beam L1 is shielded at the window 50. As a result, the intensity (light intensity) of the laser beam L1 is limited and transmitted to the outside of the housing 11. That is, the intensity of the laser beam L2 emitted outside the housing 11 is smaller than that of the laser beam L1 from the scan mirror 20.

  The reflected light from the measurement target 2 of the laser light L2 emitted from the laser range finder 1 is diffusely reflected light L3 having a light intensity much smaller than that of the laser light L2 because the laser light L2 is diffusely reflected by the measurement target 2. And enters the laser range finder 1 through the same optical path as the laser beam L2.

  As described above, when the measurement target 2 exists in the distance measurement area, the diffuse reflected light L3 having a light intensity much smaller than the laser lights L1 and L2 is incident on the scan mirror 20. That is, the light receiving unit 30 receives weak light. If the measurement target 2 does not exist in the distance measurement area, the light incident on the scan mirror 20 is substantially zero.

[3-1-2. Reference position detection area]
On the other hand, as shown in FIG. 5, in the reference position detection area (BC area), the laser light L <b> 1 scanned by the scan mirror 20 is reflected by the reflector 52 in the window 50 (opening of the housing 11). Reflected and not substantially transmitted outside the housing 11.

  The reflected light from the reflecting plate 52 of the laser light L1 scanned by the scan mirror 20 has a light intensity equivalent to that of the laser light L1 because the reflecting surface of the reflecting plate 52 has a relatively large reflectance. Have For example, when the reflecting surface of the reflecting plate 52 is made of a member that totally reflects light like a mirror, the reflected light from the reflecting plate 52 is linearly reflected linearly reflected light L4 having a relatively large light intensity. It becomes.

  Thus, in the reference position detection area, the linear reflected light L4 having a relatively large light intensity enters the scan mirror 20. That is, the light receiving unit 30 receives light having a relatively large light intensity.

  Therefore, in the signal processing unit 60, the intensity signal monitoring unit 62 determines whether or not the light intensity of the light received by the light receiving unit 30 is equal to or higher than a predetermined threshold value, so that the light is detected from the reference position detection area. The reflected light (reflected light from the reflecting plate 52) or the reflected light from the distance measuring area can be separately identified.

[3-2. When the object is located immediately before the window]
Next, a case where the object is located immediately before the window 50 will be described in comparison with a comparative example of the present embodiment. That is, in this case, the target object is arranged in a state of sticking to the window 50. In the following description, it is assumed that the target is a total reflection target that totally reflects light. However, the problem that occurs in the comparative example is not limited to the case where the target is a total reflection target. It should be noted that the same is true even when the reflectance is the same.

[3-2-1. Problems in comparative examples]
First, the problem that occurs in the comparative example when the object is positioned immediately before the window will be described with reference to FIGS. FIG. 6 is a perspective view showing an example of the configuration of the window portion 950 in the comparative example. For convenience of explanation, the reflecting plate 52 is shaded. FIG. 7 is a diagram for explaining a problem that occurs in the comparative example. 8A and 8B are graphs showing various signals acquired by the signal processing unit 60 in the comparative example in the state of FIG. 7, where FIG. 8A is a graph showing received light intensity, and FIG. 8B is a reference position detection. It is a graph which shows a signal.

  The laser range finder in the comparative example has substantially the same configuration as the laser range finder 1 in the embodiment, but the window 950 does not include the light shielding member 51 as compared with the window 50 as shown in FIG. The point is different. In other words, in the laser range finder in the comparative example, the laser light L91 scanned by the scan mirror 20 in the distance measuring area is not shielded as the laser light L92 having the same spot diameter as the laser light L1, and is external to the housing 11. Is emitted.

  Thereby, as shown in FIG. 7, when the total reflection target 2A is positioned immediately before the window portion 950, the reflected light L95 from the total reflection target 2A is linearly polarized light having the same light intensity as the laser light L1. Of light.

  As a result, the signal processing unit 60 may erroneously recognize the reflected light L95 from the total reflection target 2A as reflected light from the reference position detection area (reflected light from the reflecting plate 52). Specifically, in the comparative example, the signal output from the light receiving unit 30 is as shown in FIG. That is, a portion determined by the intensity signal monitor unit 62 to be equal to or greater than the predetermined threshold appears not only in the reference position detection area (BC area) but also in the distance measurement area (AB area). Therefore, the clock signal (pulse signal) indicating the reflected light from the reference position detection area output from the intensity signal monitor unit 62 is as shown in FIG. 8B.

  Therefore, in the comparative example, even if the intensity signal monitoring unit 62 determines whether or not the light intensity of the light received by the light receiving unit 30 is equal to or higher than a predetermined threshold, the light is reflected from the reference position detection area. Whether the light is light (reflected light from the reflecting plate 52) or reflected light from the distance measuring area cannot be separately identified.

  The reference position detection unit 63 outputs a mirror position recognition signal indicating the scanning direction (scanning angle: scanning position) of the scan mirror 20 using the signal period of the clock signal output from the intensity signal monitoring unit 62. A pulse appearing in such a ranging area (A-B area) may cause a malfunction.

[3-2-2. Effects of the present embodiment]
Next, the effects of the present embodiment when the object is located immediately before the window 50 will be described with reference to FIGS. 9 and 10. FIG. 9 is a diagram for explaining the effect produced in the present embodiment. FIG. 10 is a graph showing various signals acquired by the signal processing unit 60 in the case of the state of FIG. 9 in the present embodiment, where (a) is a graph showing received light amplitude intensity, and (b) is a reference. It is a graph which shows a position detection signal.

  In contrast to the comparative example, in the present embodiment, since the light shielding member 51 is provided in the window portion 50, the total reflection target 2A is located immediately before the window portion 50 as shown in FIG. Even in this case, the reflected light L5 from the total reflection target 2A becomes linearly polarized light having a light intensity smaller than that of the laser light L1.

  As a result, the signal processing unit 60 can determine that the reflected light L5 from the total reflection target 2A is not reflected light from the reference position detection area (reflected light from the reflecting plate 52). Specifically, in the present embodiment, the signal output from the light receiving unit 30 is as shown in FIG. That is, a portion determined by the intensity signal monitoring unit 62 to be equal to or greater than the predetermined threshold appears only in the reference position detection area (BC area). Therefore, the clock signal (pulse signal) indicating the reflected light from the reference position detection area output from the intensity signal monitor unit 62 is as shown in FIG.

  Therefore, in the present embodiment, the intensity signal monitoring unit 62 determines whether or not the light intensity of the light received by the light receiving unit 30 is equal to or higher than a predetermined threshold, so that the light is detected from the reference position detection area. The reflected light (reflected light from the reflecting plate 52) or the reflected light from the distance measuring area can be separately identified.

  Since the reference position detection unit 63 outputs a mirror position recognition signal indicating the scanning direction (scanning angle: scanning position) of the scan mirror 20 using the signal period of the clock signal output from the intensity signal monitoring unit 62, the comparison is performed. Malfunctions that occur in examples can be suppressed.

[4. Summary]
As described above, the laser range finder 1 according to the present embodiment performs measurement except for the optical path of the laser light reaching the reflecting plate 52 from the scan mirror 20 in the scan area (AC area) and the extension of the optical path. A light limiting member (a light-blocking area in this embodiment) that is disposed in the distance area (A-B area) and within the casing 11 and that limits the intensity of the laser light from the scan mirror 20 and transmits it outside the casing 11. Member 51).

  Thereby, the light intensity of the laser light output to the distance measuring area outside the housing 11 is smaller than the light intensity of the laser light output to the distance measuring area inside the housing 11. That is, even when the object is a total reflection target, the light intensity of the reflected light from the object is necessarily smaller than the light intensity from the reflecting plate 52 disposed inside the housing 11. Therefore, the laser range finder 1 can identify whether the light received by the light receiving unit 30 is reflected light from the object or reflected light from the reflecting plate 52. In other words, the reflected light from the ranging area and the reflected light from the reference position detection area can be identified. That is, the distance measurement area and the reference position detection area can be separated and identified with high accuracy. Accordingly, since it is possible to suppress erroneous recognition of reflected light from the distance measurement area as reflected light from the reference position detection area, for example, an error in angle recognition (direction recognition) of an object that may occur due to the erroneous recognition, and It is possible to reduce malfunctions of the laser range finder 1 such as an unexpected calibration operation.

  In the present embodiment, the light limiting member is provided at the opening of the housing 11 and shields a part of the spot at the opening of the laser light from the scan mirror 20 to thereby increase the intensity of the laser light. And a light shielding member 51 that transmits the outside of the housing 11 is provided.

  As described above, by providing the light shielding member 51 that blocks a part of the spot of the laser light, the light intensity of the laser light output to the distance measuring area outside the housing 11 is output to the distance measuring area inside the housing 11. It can be made smaller than the light intensity of the laser beam. On the other hand, in the window 50, the light shielding member 51 is smaller in width than the laser spot diameter, and occupies only a very small area compared to the area of the scan mirror 20 and the window 50. Therefore, the light shielding member 51 does not limit the opening area necessary for accurately measuring the distance using the reflected light from the object that is diffused light with very low light intensity. Therefore, it is possible to suppress the influence of a decrease in the amount of light due to the provision of the light shielding member 51 when the reflected light from the object passes through the window portion 50. As a result, the S / N ratio at the light receiving unit 30 can be handled in the same manner as when the light shielding member 51 is not provided. That is, the accuracy of ranging is improved by improving the angle recognition accuracy.

  In the present embodiment, the light shielding member 51 is disposed in the distance measuring area (A-B area) along the scanning direction (horizontal direction) of the laser beam by the scan mirror 20.

  Thereby, the light shielding member 51 can shield the laser light from the scan mirror 20 at an equal ratio at any position in the scanning direction. Therefore, the distance measurement area and the reference position detection area can be separated and identified with higher accuracy. In addition, it is preferable that the light shielding member 51 is arrange | positioned over the whole range-finding area.

  Moreover, in this Embodiment, the reflecting plate 52 is arrange | positioned at the edge part of a mirror scan area (AC area). In other words, the reference position detection area (BC area) is located at the end of the mirror scan area (AC area).

  Thereby, since the reflected light from the reflecting plate 52 can be received at a constant time interval, the maximum scanning angle of the scan mirror 20 can be easily calculated. Therefore, the direction (angle) of the object can be easily calculated.

  Note that the reflection plate 52 only needs to be disposed in the mirror scan area (AC area) and the housing 11, and is disposed, for example, at a position closer to the scan mirror 20 than the opening of the housing 11. Also good. Further, for example, the reflection plate 52 may be arranged at the center of the mirror scan area (AC area). Further, for example, the reflection plate 52 may not be disposed on the same plane (XY plane) as the light shielding member 51, and may be disposed at a position closer to the scan mirror 20 than the light shielding member 51.

(Modification 1)
Next, Modification 1 of the embodiment will be described with reference to FIG. FIG. 11 is a perspective view showing an example of the configuration of the window portion 250 in the first modification of the embodiment. For the convenience of explanation, the light shielding members 251a and 251b and the reflection plate 52 are shaded.

  The laser range finder according to the present modification is substantially the same as the above embodiment, but as shown in FIG. 11, the window portion 250 includes a plurality (two in this modification) of light shielding members 251a and 251b. Is different. Even with such a configuration in which a plurality of light shielding members 251a and 251b are arranged, the same effects as those of the above embodiment can be obtained.

  In this modification, the configuration in which the two light shielding members 251a and 251b are arranged has been described as an example, but the configuration in which three or more light shielding members are arranged may be used.

(Modification 2)
Next, a second modification of the embodiment will be described with reference to FIG. FIG. 12 is a perspective view showing an example of the configuration of the window part 350 in the second modification of the embodiment. For the convenience of explanation, the neutral density filter 351 and the reflection plate 52A are shaded.

  The laser range finder according to this modification is substantially the same as that of the above embodiment, but as shown in FIG. 11, the window portion 350 includes a neutral density filter 351 instead of the light shielding member 51, and instead of the reflection plate 52. The difference is that the reflector 52A is provided.

  The neutral density filter 351 is disposed in the distance measuring area (AB area) of the mirror scan area (AC area) and in the housing 11, and the intensity (light intensity) of the laser light L <b> 1 from the scan mirror 20. ) And is transmitted to the outside of the housing 11. Specifically, the neutral density filter 351 is provided in the opening of the housing 11, and the laser light L1 from the scan mirror 20 is transmitted. For example, an ND (Neutral Density) filter that limits the intensity (light intensity) and transmits the light to the 11th floor of the housing 11. The neutral density filter 351 suppresses the intensity of light having the wavelength of the laser light L1.

  Thus, even if it is the structure using the neutral density filter 351 as a light limiting member, there exists an effect similar to the said embodiment.

  Further, by using the neutral density filter 351 as the light limiting member, the neutral density filter 351 can be disposed on the entire surface other than the region where the reflection plate 52A of the transmission member 53 is provided, as shown in FIG. . That is, in the embodiment, the light shielding member 51 is arranged so as to shield a part of the spot of the laser beam L1, but in this modification, the neutral density filter 351 includes all of the spot of the laser beam L1. Can be arranged.

  Thereby, when the laser range finder 1 is assembled, it becomes difficult to require high accuracy for positioning the light limiting member (the neutral density filter 351 in this modification) and the scan mirror 20. In other words, the assembly of the laser range finder 1 can be facilitated.

  Further, even when the scan mirror 20 performs two-dimensional scanning with the laser light L1, the same effects as those of the above-described embodiment can be obtained.

  In addition, the reflecting plate 52A in the present modification is formed in the entire area of the window portion 250 in the Y-axis direction (vertical direction) as compared to the reflecting plate 52 in the above embodiment.

  Thereby, even when the scan mirror 20 scans the laser beam L1 two-dimensionally, the same effect as the above-described embodiment can be obtained.

  Further, the scan mirror 20 swings around at least two axes including a predetermined axis, and the reflection plate 52A is disposed so as to close the opening of the housing 11 in a direction parallel to the predetermined axis. As a result, the following effects are obtained.

  That is, when the difference between the intensity of the reflected light from the distance measuring area and the intensity of the reflected light from the reflecting plate 52A is small, it is difficult to separately identify the distance measuring area and the reference position detection area. Even in such a case, it is unlikely that there is a high reflection with a constant width in the Y-axis direction (vertical direction) of the distance measurement area, so reflected light that appears with a constant period and a constant intensity is reflected from the reflector 52A. It can be regarded as light. In this way, the distance measurement area and the reference position detection area can be separated and identified by regarding the reflected light that appears with a constant period and a constant intensity as the reflected light from the reflecting plate 52A. Therefore, even when the difference between the intensity of the reflected light from the distance measuring area and the intensity of the reflected light from the reflecting plate 52A is small, the same effect as in the above embodiment can be obtained.

(Other embodiments)
Although the laser range finder according to the embodiments and modifications of the present invention has been described above, the present invention is not limited to these embodiments and modifications.

  For example, the laser spot shape of the laser light L1 may be any of a substantially circular shape, a substantially elliptical shape, a line shape, a rectangular shape, and the like, and may be appropriately adjusted together with the shape of the light shielding member, for example.

  Further, the overlapping area between the light shielding member and the laser spot LS of the laser beam L1 from the scan mirror 20 has a correlation with the intensity (light intensity) of the laser beam L2 emitted from the laser range finder 1. Specifically, the intensity of the laser beam L2 decreases as the overlapping area increases. Therefore, the overlapping area is set so that the light intensity when the laser light L2 is totally reflected is significantly smaller than the light intensity from the reflected light from the reference position detection area (reflected light from the reflecting plate). That's fine. Specifically, the overlapping area is smaller than a threshold value used for determining whether the light intensity when the laser light L2 is totally reflected is reflected light from the reference position detection area in the intensity signal monitoring unit 62. What should I do.

  Further, the width of the light shielding member (the size in the direction orthogonal to the scanning direction of the laser beam L1 by the scan mirror 20) is not particularly limited, but is sufficient to maintain a good S / N ratio in the light receiving unit 30. It is preferable that the width is. For example, the width of the light shielding member is preferably about equal to or less than the laser spot diameter of the laser beam L1 in the opening of the housing 11.

  In the above description, the laser range finder has been described as a coaxial optical system in which the scan mirror 20 and the light receiving unit 30 are configured by a coaxial path. However, the laser range finder is configured by separating the scan mirror 20 and the light receiving unit 30 from each other. It may be an optical system.

  Furthermore, the above embodiments and modifications may be combined.

  The embodiment described above can be applied to a laser range finder that detects the distance of an object.

DESCRIPTION OF SYMBOLS 1 Laser range finder 2 Measurement target 2A Total reflection target 10 Light source 11 Case 20 Scan mirror 30 Light-receiving part 40 Beam splitter 50, 250, 350, 950 Window part 51, 251a, 251b Light-shielding member 52, 52A Reflecting plate 53 Transmission member 60 Signal processing unit 61 Ranging signal processing unit 62 Intensity signal monitoring unit 63 Reference position detection unit 64 Calculation unit 351 Neutral filter

Claims (6)

A laser range finder that measures the distance to an object,
A housing,
A light source disposed in the housing and emitting laser light;
A oscillating mirror that scans a laser beam from the light source in a scanning region;
A reflecting plate disposed in the scanning region and in the housing and reflecting the laser beam from the oscillating mirror;
Of the scanning area, the optical path of the laser beam reaching the reflector from the oscillating mirror and the distance measuring area excluding the extension of the optical path, and the laser beam from the oscillating mirror are arranged in the housing. A light limiting member that limits the strength and transmits outside the housing;
A light receiving unit that receives reflected light from the object and the reflector plate of the laser beam scanned by the swing mirror;
A laser range finder, comprising: a signal processing unit that calculates a direction of the object with respect to the laser range finder using a timing at which the light receiving unit receives the reflected light. The light limiting member is provided in the opening of the casing, and blocks a part of the spot in the opening of the laser light from the oscillating mirror, thereby limiting the intensity of the laser light. The laser range finder according to claim 1, wherein the laser range finder is a light shielding member that transmits to the outside of the housing. The laser range finder according to claim 2, wherein the light shielding member is disposed in the distance measuring area along a scanning direction of laser light by the oscillating mirror. The laser range finder according to claim 1, wherein the light limiting member is a neutral density filter that is provided at an opening of the housing and limits the intensity of the laser light and transmits the laser light to the outside of the housing. The laser range finder according to claim 1, wherein the reflecting plate is disposed at an end of the scanning region. The oscillating mirror oscillates about at least two axes including a predetermined axis,
The laser range finder according to any one of claims 1 to 5, wherein the reflecting plate is arranged so as to close an opening of the housing in a direction parallel to the predetermined axis.

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