WO2024053081A1

WO2024053081A1 - Scanning distance measuring device

Info

Publication number: WO2024053081A1
Application number: PCT/JP2022/033841
Authority: WO
Inventors: 正幸大牧; 菜月高川
Original assignee: 三菱電機株式会社
Priority date: 2022-09-09
Filing date: 2022-09-09
Publication date: 2024-03-14

Abstract

A scanning distance measuring device (1) comprises: a laser light source (101) that emits laser light; a condensing lens (301) that concentrates laser light which has been reflected by a measurement target object (2); a first light-receiving element (411) that detects the laser light which has been concentrated by the condensing lens (301); a second light-receiving element (421) that is disposed at a position apart from the optical axis (302) by a predetermined distance; and a processing circuit (440) that determines whether or not the measurement target object (2) is present in a distance measuring region (3) on the basis of the laser light which has been detected by the second light-receiving element (421).

Description

Scanning distance measuring device

The present disclosure relates to a scanning distance measuring device.

In recent years, distance measuring devices that use laser beams such as optical beams have been used to ensure safety during automatic driving of automobiles (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 5-34455

Conventional technology requires separate light-receiving elements and separate light-emitting elements for long-range distance measurement and short-range distance measurement. Therefore, in the conventional technology, there is a problem that it is difficult to detect the object to be measured from a distance of several meters or more and to control the laser light source for executing the interlock with a simple configuration.

An object of the present disclosure is to provide a scanning distance measuring device that has a simple configuration, is capable of detecting an object to be measured, and is capable of interlocking even if the object is several meters away from the object. The purpose is to provide.

A scanning distance measuring device according to one aspect of the present disclosure includes:
a laser light source that emits laser light;
A condensing lens that condenses the laser beam reflected by the object to be measured;
a first light receiving element that is arranged at a position intersecting the optical axis of the condenser lens and detects the laser beam focused by the condenser lens;
a second light receiving element disposed at a predetermined distance from the optical axis;
and a processing circuit that determines whether the object to be measured exists within the distance measurement area based on the laser beam detected by the second light receiving element.

According to the present disclosure, it is possible to provide a scanning distance measuring device that can detect an object to be measured and can perform interlock even if the object is several meters or more away from the object. .

1 is a diagram schematically showing the configuration of a scanning distance measuring device according to Embodiment 1. FIG. FIG. 2 is a perspective view schematically showing an optical path of a laser beam in a scanning distance measuring device. FIG. 2 is a top view schematically showing the optical path of a laser beam in the scanning distance measuring device. FIG. 3 is a perspective view showing an example of the position of a first light receiving element and the position of a second light receiving element. FIG. 3 is a side view showing an example of the position of a first light receiving element and the position of a second light receiving element. FIG. 2 is a diagram schematically showing a laser beam reflected by a measurement object located at a longer distance than the example shown in FIG. 1; FIG. 3 is a diagram schematically showing another example of a scanning distance measuring device. FIG. 3 is a diagram schematically showing another example of a scanning distance measuring device. FIG. 3 is a diagram showing a laser beam scanning area, which is an area where laser light is emitted. FIG. 3 is a diagram showing a laser beam scanning area, which is an area where a laser beam is emitted. FIG. 3 is a diagram showing a laser beam scanning area, which is an area where laser light is emitted. FIG. 2 is a diagram schematically showing an optical system in a scanning distance measuring device. FIG. 3 is a perspective view showing an example of the position of a first light receiving element and the position of a second light receiving element. FIG. 3 is a side view showing an example of the position of a first light receiving element and the position of a second light receiving element. FIG. 2 is a diagram schematically showing an example of a processing circuit. In the examples shown in FIGS. 4 and 5, the position of the second light-receiving element, the position of the second light-receiving element, and the object to be measured are transferred from the scanning distance measuring device capable of determining whether or not the object to be measured exists. It is a graph showing the relationship with the maximum distance to. In the examples shown in FIGS. 13 and 14, the position of the second light-receiving element, the position of the second light-receiving element, and the object to be measured are transferred from the scanning distance measuring device capable of determining whether or not the object to be measured exists. It is a graph showing the relationship with the maximum distance to.

Various embodiments will be described below with reference to the drawings. In the drawings, identical or corresponding components are designated by the same reference numerals.
Embodiment 1.
FIG. 1 is a diagram schematically showing the configuration of a scanning distance measuring device 1 according to the first embodiment.
FIG. 2 is a perspective view schematically showing the optical path of a laser beam in the scanning distance measuring device 1. As shown in FIG.
FIG. 3 is a top view schematically showing the optical path of a laser beam in the scanning distance measuring device 1. As shown in FIG.
FIG. 4 is a perspective view showing an example of the position of the first light receiving element 411 and the position of the second light receiving element 421.
FIG. 5 is a side view showing an example of the position of the first light receiving element 411 and the position of the second light receiving element 421.

<Scanning distance measuring device 1>
The scanning distance measuring device 1 includes a laser light source 101 that emits a laser beam, a condensing lens 301 that condenses the laser beam reflected by the object to be measured 2, and detects the laser beam condensed by the condensing lens 301. a second light receiving element 421 disposed at a predetermined distance from the optical axis 302 of the condenser lens 301, and a processing circuit 440. In this application, "laser light" means transmitting laser light 510 or receiving laser light 520.

<First light receiving circuit 410>
The first light receiving circuit 410 has a first light receiving element 411. As shown in FIG. 1, the first light receiving element 411 is arranged on the optical axis 302 of the condenser lens 301. The first light receiving element 411 detects the received laser beam 520 focused by the focusing lens 301. In other words, the first light receiving element 411 is arranged at a position intersecting the optical axis 302 of the condenser lens 301. Thereby, the distance from the condenser lens 301 to the first light receiving element 411 can be increased. A signal corresponding to the laser beam detected by the first light receiving element 411 is sent to the processing circuit 440.

<Second light receiving circuit 420>
The second light receiving circuit 420 has a second light receiving element 421 different from the first light receiving element 411. The second light receiving element 421 is not arranged on the optical axis 302 of the condenser lens 301. In other words, the second light receiving element 421 is arranged at a position that does not intersect the optical axis 302 of the condenser lens 301. That is, the second light-receiving element 421 is placed at a position separated from the optical axis 302 by a predetermined distance. In this case, the distance between the optical axis 302 and the second light receiving element 421 is a "predetermined distance". A signal corresponding to the laser beam detected by the second light receiving element 421 is sent to the processing circuit 440.

<Condensing lens 301>
When the transmitted laser beam 510 reaches the measurement object 2, the laser beam (i.e., the transmission laser beam 510) is scattered or reflected by the measurement object 2, and a part of the laser beam (i.e., the reception laser beam 520) is scanned. incident on the distance measuring device 1. In the scanning distance measuring device 1 , the received laser beam 520 is focused by the condensing lens 301 and enters the first light receiving element 411 . Thereby, the first light receiving element 411 detects the received laser beam 520.

In the example shown in FIG. 1, the received laser light 520 that is scattered by the object to be measured 2 and enters the scanning distance measuring device 1 forms a divergence angle when viewed from the scanning distance measuring device 1. This is the radius of the received laser beam 520 on the measurement object 2 (in the case of an ellipse, the major axis) and the radius of the received laser beam 520 received by the condenser lens 301, relative to the distance from the scanning distance measuring device 1 to the measurement object 2. (In the case of an ellipse, the major axis) is large enough to not be ignored.

FIG. 6 is a diagram schematically showing the laser beam reflected by the measurement object 2 which is located at a longer distance than the example shown in FIG.
In the example shown in FIG. 6, the received laser light 520 that is scattered by the measurement object 2 and enters the scanning distance measuring device 1 is parallel when viewed from the scanning distance measuring device 1. This is based on the distance from the scanning distance measuring device 1 to the object to be measured 2, the received laser beam 520, the radius on the object to be measured 2 (in the case of an ellipse, the major axis), and the radius of the light received by the condenser lens 301 ( In the case of an ellipse, the difference from the long axis) is negligible.

Since the amount of light received is inversely proportional to the square of the distance measured, it is desirable to design the scanning distance measuring device 1 so that the farther the distance, the more the light is focused on the first light receiving element 411.

<Processing circuit 440>
The received laser beam 520 that has entered the first light receiving element 411 is converted into a current according to the amount of incident light, and further converted into a voltage by a Trans Impedance Amplifier (TIA) of the first light receiving circuit 410. This signal is sent to the processing circuit 440, and distance measurement is performed using a direct time of flight (ToF) method. The direct ToF method is a method that measures the time it takes for the light (pulse modulated light) emitted from the scanning range finder 1 to be reflected by the measurement object 2 and to be received by the scan range finder 1. be.

The processing circuit 440 controls the laser light source 101. For example, processing circuit 440 controls the output of laser light source 101, such as radiation density or light intensity. The processing circuit 440 receives a signal corresponding to the laser light detected by the first light receiving element 411. For example, the processing circuit 440 controls the output of the laser light source 101 based on the laser light detected by the first light receiving element 411.

The processing circuit 440 receives a signal corresponding to the laser beam detected by the second light receiving element 421. For example, the processing circuit 440 determines whether the measurement target object 2 exists within the distance measurement area 3 based on the laser beam detected by the second light receiving element 421. The processing circuit 440 may be configured with a single central processing unit or may include a plurality of central processing units.

The distance measurement area 3 is an area that is set as an area that requires interlock in order to meet safety standards (FIGS. 10 and 11, which will be described later). Interlocking means stopping the transmission of the transmitting laser beam 510 or reducing the output of the transmitting laser beam 510. The distance measurement area 3 is a three-dimensional space in which the transmitted laser beam 510 from the scanning distance measurement device 1 to the measurement object 2 is scanned. For example, the distance measurement area 3 is set as a distance from the scanning distance measurement device 1 that requires interlock in order to meet safety standards.

<Other components and operation of scanning ranging device 1>
As shown in FIG. 2, the scanning distance measuring device 1 includes a first cylindrical lens 102, a mirror 103 (for example, a bending mirror), a second cylindrical lens 104, and a separation mirror 201 as a light control element. It may also have. In this case, mirror 103 is provided between first cylindrical lens 102 and second cylindrical lens 104. The mirror 103 can convert the optical path of the light from the first cylindrical lens 102. Therefore, when the scanning distance measuring device 1 includes the mirror 103, the overall dimensions of the scanning distance measuring device 1, such as the dimensions of the housing, can be reduced.

Of the transmitted laser light 510 emitted from the laser light source 101 , the light emitted in the direction parallel to the fast axis (also referred to as the "fast axis direction" or "fast direction") is transmitted by the first cylindrical lens 102 . , converted into approximately parallel light. The shape of the first cylindrical lens 102 has a curvature in the fast direction. Of the transmitted laser light 510, the light emitted in the direction parallel to the slow axis (also referred to as the "slow axis direction" or "slow direction") is not affected by the curvature of the first cylindrical lens 102. Of the transmitted laser light 510 emitted from the laser light source 101, the light emitted in the slow direction continues to spread in the slow direction.

Instead of the first cylindrical lens 102, a toroidal lens or a cross cylindrical lens having curvature also in the slow direction may be used. When a lens having a negative curvature in the slow direction is used, the spread angle of the transmitted laser beam 510 in the slow direction increases, and the distance between the first cylindrical lens 102 and the second cylindrical lens 104 can be narrowed.

After the transmitted laser beam 510 passes through the first cylindrical lens 102, the light spreading in the slow direction of the transmitted laser beam 510 is converted into substantially parallel light by the second cylindrical lens 104. As a result, the transmitted laser light 510 that has passed through the second cylindrical lens 104 is irradiated farther without spreading significantly.

The first cylindrical lens 102 and the second cylindrical lens 104 are effective when the width of the laser beam in the slow direction is larger than the width in the fast direction. Generally, the first cylindrical lens 102 and the second cylindrical lens 104 are effective when using a high-power laser light source. This is because the wider the light source width, the larger the spread angle of the light after passing through the lens that converts it into parallel light.

On the other hand, the longer the focal length of the lens that converts the light into parallel light, the smaller the divergence angle can be. Therefore, the laser light in the slow direction is almost parallelized by the second cylindrical lens 104 that is far from the light source. Can be converted into light. That is, laser light in the slow direction can be converted into substantially parallel light by the second cylindrical lens 104 having a long focal length.

For the same reason, this form is not necessarily required when the difference in the light source width between the slow direction and the fast direction is small, such as when a medium-power laser light source is sufficient or when the light source is coupled to a fiber. For example, first cylindrical lens 102 and second cylindrical lens 104 may have the same focal length. For example, one collimator lens may be used instead of the first cylindrical lens 102 and the second cylindrical lens 104.

The scanning distance measuring device 1 may include a first scanning mirror 202 and a second scanning mirror 203. In this case, the transmitted laser beam 510 converted into substantially parallel light is guided by the separation mirror 201 along the same optical path as the received laser beam 520, and is guided toward the first scanning mirror 202. Further, the transmitted laser beam 510 is guided by the first scanning mirror 202 toward the second scanning mirror 203, and is emitted from the scanning distance measuring device 1 to the ranging area 3 by the second scanning mirror 203.

As shown in FIG. 2, the first scanning mirror 202 and the second scanning mirror 203 are arranged on a common optical path of the transmitting laser beam 510 and the receiving laser beam 520. The first scanning mirror 202 and the second scanning mirror 203 have a structure that allows them to rotate around mutually orthogonal axes. Thereby, the radiation angle of the transmitted laser beam 510 from the scanning distance measuring device 1 can be controlled.

The shapes and positions of the first scanning mirror 202 and the second scanning mirror 203 are not limited to the example described in this embodiment.

The focal length of the first cylindrical lens 102 is significantly different from the focal length of the second cylindrical lens 104. As a result, the beam diameter of the transmitted laser beam 510 is different between the fast direction and the slow direction. In the example shown in FIGS. 1 and 2, the beam diameter of the transmission laser beam 510 in the slow direction is three times or more the beam diameter of the transmission laser beam 510 in the fast direction. Therefore, the shape of the separation mirror 201 is, for example, a rectangle that is long in the slow direction.

As the difference in the light source width in the slow direction and the fast direction becomes smaller, the difference in the beam diameter of the transmitted laser beam 510 in the slow direction and the fast direction becomes smaller, so the shape of the separation mirror 201 does not necessarily have to be rectangular. , may be circular or square.

For example, the separation mirror 201 guides the laser beam reflected by the measurement object 2 toward the condenser lens 301. The separation mirror 201 is a component for guiding the received laser beam 520 to the same optical path, but the separation mirror 201 does not necessarily have to be a small piece mirror. For example, instead of the separating mirror 201, a component such as a polarizing beam splitter that can switch between reflection and transmission according to orthogonal polarization directions may be used as the light control element. Since the polarization direction of the received laser beam 520 is not determined, even if a polarizing beam splitter is used instead of the separation mirror 201, the total amount of the received laser beam 520 will not be attenuated.

7 and 8 are diagrams schematically showing other examples of the scanning distance measuring device 1.
As shown in FIGS. 7 and 8, the separation mirror 201 does not necessarily need to be placed on the optical axis 302 of the condenser lens 301. In the example shown in FIG. 7, the separation mirror 201 is disposed at a position shifted in a direction perpendicular to the optical axis 302 of the condenser lens 301. In the example shown in FIG. Thereby, the output of the laser light source 101 can be increased, and the distance measurement area 3 can be further expanded.

For example, the separation mirror 201 may be placed at a position offset from the optical axis 302 of the condenser lens 301 in a direction parallel to the fast axis of the laser light emitted from the laser light source 101. In this case, the separation mirror 201 can be downsized and the light receiving efficiency can be increased. As a result, the scanning type distance measuring device 1 can be downsized.

In the example shown in FIG. 8, the second light receiving element 421 and the second light receiving circuit 420 are located apart from the first light receiving circuit 410. In this case, the second light receiving circuit 420 (specifically, the second light receiving element 421) collects light with respect to the first light receiving circuit 410 (specifically, the first light receiving element 411), for example. It is sufficient if it is located on the opposite side to the lens 301.

As shown in FIGS. 7 and 8, the second light receiving element 421 may be located on the opposite side of the separation mirror 201 with respect to the optical axis 302 of the condenser lens 301.

FIG. 9 is a diagram showing the laser beam scanning area 5, which is the area where the transmission laser beam 510 is emitted.
In FIG. 9, the laser beam scanning area 5 indicates an angular area surrounded by four solid lines. The scanning distance measuring device 1 can freely scan the inside of the laser beam scanning area 5 with the transmitted laser beam 510 using, for example, the first scanning mirror 202 and the second scanning mirror 203. The scanning distance measuring device 1 may scan the transmitted laser beam 510 by means other than the first scanning mirror 202 and the second scanning mirror 203.

Generally, the pulse width is several ns, and it is necessary to detect steep rise or fall times, so the light receiving element, light receiving circuit, and processing circuit require a bandwidth on the order of several 100 MHz to several GHz. becomes.

In general, safety standards for laser products are specified in terms of energy, so the narrower the pulse width, the higher the amount of light can be set for the same amount of energy. Therefore, it is desirable to use the direct ToF method as a long-distance distance measuring method. In the case of the direct ToF method, by narrowing the pulse width until it reaches the detection limit in the light receiving circuit, it is possible to increase the amount of spectral light, making it possible to measure distances further.

FIG. 10 is a diagram showing a laser beam scanning area 5, which is an area from which a transmission laser beam 510 is emitted.
FIG. 11 is a diagram showing a laser beam scanning area 5, which is an area where a transmission laser beam 510 is emitted. In FIG. 11, the object to be measured 2 is located closer to the scanning distance measuring device 1 than in the example shown in FIG.
In FIGS. 10 and 11, distance measurement area 3 is an area surrounded by a broken line. In the examples shown in FIGS. 10 and 11, a state in which the object to be measured 2 is present in the distance measurement area 3 is shown. In the example shown in FIG. 10, the measurement object 2 receives the transmitted laser beam 510 at only two points. In the example shown in FIG. 11, a state in which the object to be measured 2 is present is shown, and the object to be measured 2 receives the transmitted laser beam 510 at five points.

In the scanning distance measuring device 1, the transmitted laser light 510 is pulse-modulated, for example. In this case, the transmitted laser beam 510 is intermittently emitted within the laser beam scanning area 5, and on the surface (approximately spherical surface) at the same distance from the scanning distance measuring device 1, the portion indicated by dots in FIGS. is the part irradiated with the transmission laser beam 510 and is also the measurement point.

As shown in FIG. 10, the farther from the scanning distance measuring device 1, the wider the distance between the measurement points. On the other hand, as shown in FIG. 11, the closer the measurement points are to the scanning distance measuring device 1, the narrower the distance between the measurement points.

FIG. 12 is a diagram schematically showing the optical system in the scanning distance measuring device 1. As shown in FIG.
When the distance from the scanning distance measuring device 1 to the measurement target 2 is shorter than a specific distance, the received laser beam 520 is not completely focused on the first light receiving element 411 of the first light receiving circuit 410. In the example shown in FIG. 12, the diameter of the received laser beam 520 that enters the first light receiving circuit 410 is indicated by D. In the example shown in FIG. The diameter of the received laser beam 520 that enters the first light receiving circuit 410 is also referred to as a "spot diameter."

In the example shown in FIG. 12, when the condenser lens 301 is an ideal single lens, the diameter D on the first light receiving circuit 410, the focal length f of the condenser lens 301, the shift amount df of the condensing position, The relationship between the lens aperture diameter AP and the distance z from the condenser lens 301 to the measurement object 2 is expressed by the following equation.
D/AP=df/(df+f)...(Formula 1)
1/f=1/(df+f)+1/z...(Formula 2)

From

Equations

1 and 2, Equation 3 is obtained as shown below.
D=AP×f/z...(Formula 3)

As shown in Equation 3, the diameter D on the first light receiving circuit 410 is proportional to the focal length f of the condenser lens 301 and inversely proportional to the distance z from the condenser lens 301 to the measurement target 2. Therefore, as the distance z from the condenser lens 301 to the measurement object 2 becomes shorter, the diameter D on the first light receiving circuit 410 becomes larger.

FIG. 13 is a perspective view showing an example of the position of the first light receiving element 411 and the position of the second light receiving element 421.
FIG. 14 is a side view showing an example of the position of the first light receiving element 411 and the position of the second light receiving element 421.
As shown in FIGS. 13 and 14, the second light receiving element 421 is not arranged on the optical axis 302 of the condenser lens 301. In other words, the second light receiving element 421 is arranged at a position that does not intersect the optical axis 302 of the condenser lens 301. For example, the second light receiving element 421 is placed at a distance of D/2 (that is, half the spot diameter) from the optical axis 302. Thereby, it is possible to determine whether the diameter of the received laser beam 520 that has entered the first light receiving circuit 410 is equal to or larger than D based on the amount of light received by the second light receiving element 421. As a result, it is possible to determine whether the distance from the scanning distance measuring device 1 to the measurement object 2 (for example, the distance z from the condenser lens 301 to the measurement object 2) satisfies Equation 3. For example, it can be determined whether the distance from the scanning distance measuring device 1 to the object to be measured 2 is less than or equal to z.

The received laser light 520 incident on the second light receiving element 421 is converted into a current according to the amount of incident light, and further converted into a voltage by the TIA of the second light receiving circuit 420. Since the second light-receiving element 421 is not intended for distance measurement, it is not necessary to be able to receive light in a pulsed form. The scanning distance measuring device 1 only needs to be able to determine whether or not the received laser beam 520 has entered the second light receiving element 421.

FIG. 15 is a diagram schematically showing an example of the processing circuit 440.
Processing circuit 440 has a comparator 441. Comparator 441 compares the light reception signal and a threshold voltage. The light reception signal is a signal corresponding to a voltage converted according to the amount of light incident on the second light reception element 421. When the light reception signal is equal to or higher than the threshold voltage, the comparator 441 outputs a detection signal. For example, if the signal corresponding to the voltage converted according to the amount of light incident on the second light receiving element 421 is equal to or higher than the threshold voltage, the processing circuit 440 determines that the measurement target object 2 exists within the distance measurement area 3. do. The processing circuit 440 can control the laser light source 101 according to the determination result (for example, the detection signal).

In the example shown in FIG. 15, the light reception signal is, for example, a positive theory signal. On the other hand, even if the light reception signal is a negative theory signal, it can be processed in the same way as when the light reception signal is a positive theory signal.

The light reception signal may be input to an analog-to-digital converter, the light reception signal may be directly processed as a digital signal, and the signal may be compared with a digital threshold.

In a general scanning distance measuring device, it is necessary to detect the steep rise time or fall time of a signal with a pulse width of several ns. A band on the order of 100 MHz to several GHz is required.

On the other hand, in the present embodiment, the second light receiving element 421, the second light receiving circuit 420, and the processing circuit 440 may all have a frequency band of several MHz or less, making the scanning distance measuring device 1 inexpensive. Can be configured. Therefore, it is not necessary to use a TIA for the output current of the second light receiving element 421, and it is sufficient to simply connect a resistor in series.

Since the second light receiving circuit 420 and the second light receiving element 421 need to receive reflected light from a short distance, the sensitivity of the second light receiving element 421 and the gain of the second light receiving circuit 420 are different from those of the first light receiving element 420. Each needs to be lower than the light receiving element 411 and the first light receiving circuit 410. For example, an inexpensive photodiode may be used as the second light receiving circuit 420, or the feedback resistance value that determines the gain of the TIA may be reduced.

FIG. 16 shows a scanning type that can determine the position of the second light receiving element 421, the position of the second light receiving element 421, and whether or not the measurement target 2 exists in the example shown in FIGS. 4 and 5. 2 is a graph showing the relationship between the distance measuring device 1 and the maximum distance from the measurement target 2. FIG. Specifically, FIG. 16 shows a positional relationship in which the detection value (output voltage) detected by the second light receiving element 421 matches the threshold voltage. The vertical axis in FIG. 16 indicates the distance from the scanning distance measuring device 1 to the measurement target 2, and the horizontal axis indicates the distance from the optical axis 302 of the condensing lens 301 to the second light receiving element 421. ing. By setting the position of the second light receiving element 421, it is possible to determine the limit of the distance from the scanning distance measuring device 1 to the measurement object 2, which makes it possible to determine whether or not the measurement object 2 exists. can.

As shown in FIG. 16, by appropriately setting the position from the optical axis 302 of the condenser lens 301 to the second light receiving element 421, the range of the ranging area 3 can be appropriately controlled. As a result, it becomes possible to determine whether or not the measurement target object 2 exists within the distance measurement area 3.

Generally, the dynamic range of a light receiving circuit is limited to about 3 to 4 digits, so the distance measurement range is about 30 to 100 times. For example, if it is possible to measure a distance of 300 m or more, it is difficult to measure a distance of 3 m or less. For example, if it is possible to measure a distance of 1000 m or more, it is difficult to measure a distance of 10 m or less.

In this embodiment, the scanning distance measuring device 1 is configured such that the distance measuring area 3 is several meters or more, for example. In this case, as shown in FIG. 16, the distance measurement area 3 is sensitive to the distance from the optical axis 302 of the condenser lens 301 to the second light receiving element 421, and the range of the distance measurement area 3 is controlled. difficult to do. Furthermore, since the external size of the light receiving element is generally around several mm, it is difficult to use other elements in place of the light receiving element.

Therefore, in the examples shown in FIGS. 8, 13, and 14, the second light receiving element 421 and the second light receiving circuit 420 are located apart from the first light receiving circuit 410. In this case, the second light receiving circuit 420 (specifically, the second light receiving element 421) collects light with respect to the first light receiving circuit 410 (specifically, the first light receiving element 411), for example. It is sufficient if it is located on the opposite side to the lens 301. Thereby, the ranging area 3 can be set with high accuracy.

FIG. 17 shows a scanning type that can determine the position of the second light receiving element 421, the position of the second light receiving element 421, and whether or not the measurement target 2 exists in the example shown in FIGS. 13 and 14. 2 is a graph showing the relationship between the distance measuring device 1 and the maximum distance from the measurement target 2. FIG. By setting the position of the second light receiving element 421, it is possible to determine the limit of the distance from the scanning distance measuring device 1 to the measurement object 2, which makes it possible to determine whether or not the measurement object 2 exists. can.
The data shown in FIG. 17 has a gentler slope than the data shown in FIG. 16. That is, in the configurations shown in FIGS. 13 and 14, the range of the ranging area 3 can be easily controlled. As a result, the range in which the second light receiving element 421 can be arranged can be expanded.

With the configurations shown in FIGS. 13 and 14, the ranging area 3 can be set freely. Furthermore, by setting the distance measurement area 3 as an area that requires interlock to meet safety standards, it is possible to set the distance measurement area 3 as an area that requires interlocking to meet the safety standards. A locking function can be installed in the scanning distance measuring device 1.

In the case of continuous operation of the scanning distance measuring device 1, it is desirable to automatically release the interlock when the object 2 to be measured no longer exists within the distance measuring area 3. Therefore, when automatically releasing the interlock, the radiation density of the transmitted laser beam 510 is reduced.

When the object 2 to be measured exists within the ranging area 3, the processing circuit 440 controls the laser light source 101 so that the radiation density of the transmitted laser light 510 is reduced. As a result, the radiation density of the transmitted laser beam 510 irradiated onto the measurement object 2 is reduced. In this case, in the example shown in FIG. 10, the measurement object 2 receives the transmitted laser beam 510 at only two points. Thereby, the cumulative amount of light within a unit time with respect to the measurement target object 2 can be suppressed to less than the safety standard. Therefore, by controlling the radiation density or the amount of light, the interlock can be automatically released when the measurement object 2 no longer exists within the distance measurement area 3.

Alternatively, the interlock may be executed by reducing the amount of transmitted laser light 510. In this case, if the object 2 to be measured exists within the distance measurement area 3, the processing circuit 440 controls the laser light source 101 so that the amount of transmitted laser light 510 is reduced. Furthermore, it is desirable to similarly lower the threshold voltage for determining the distance measurement area 3.

As described above, according to the present disclosure, it is possible to detect the object to be measured and perform interlocking even if the object is several meters away from the object with a simple configuration. A scanning ranging device can be provided.

Embodiment 2.
By setting distance measurement area 3 as an area that requires interlock to meet safety standards, and stopping light emission when measurement target 2 exists within distance measurement area 3, even if interlock is executed, good.

Furthermore, similarly to Embodiment 1, the radiation density or light amount of the transmitted laser beam 510 may be set so that the cumulative amount of light per unit time to the measurement object 2 can be suppressed to less than the safety standard. Thereby, even if the measurement target object 2 no longer exists within the distance measurement area 3, detection can be performed, and the interlock can also be automatically released.

The features of each embodiment described above can be combined with each other.

1 Scanning distance measuring device, 2 Measurement object, 3 Ranging area, 5 Laser beam scanning area, 101 Laser light source, 102 First cylindrical lens, 103 Mirror, 104 Second cylindrical lens, 201 Separation mirror, 202nd 1 scanning mirror, 203 second scanning mirror, 301 condensing lens, 302 optical axis, 410 first light receiving circuit, 411 first light receiving element, 420 second light receiving circuit, 421 second light receiving element, 440 Processing circuit, 510 transmitting laser light (laser light), 520 receiving laser light (laser light).

Claims

a laser light source that emits laser light;
A condensing lens that condenses the laser beam reflected by the object to be measured;
a first light receiving element that is arranged at a position intersecting the optical axis of the condenser lens and detects the laser beam focused by the condenser lens;
a second light receiving element disposed at a predetermined distance from the optical axis;
A scanning distance measuring device comprising: a processing circuit that determines whether the object to be measured exists within the distance measuring area based on the laser beam detected by the second light receiving element.
further comprising a first light receiving circuit having the first light receiving element,
The second light-receiving element is arranged at a distance of D/2 from the optical axis, where D is the diameter of the laser beam that enters the first light-receiving circuit. Scanning distance measuring device.
If the signal corresponding to the voltage converted according to the amount of light incident on the second light receiving element is equal to or higher than a threshold voltage, the processing circuit determines that the object to be measured exists within the distance measurement area. 3. The scanning distance measuring device according to item 1 or 2.
The scanning distance measuring device according to any one of claims 1 to 3, wherein the distance measuring area is an area that requires an interlock that satisfies safety standards.
The scanning distance measuring device according to any one of claims 1 to 4, wherein the second light receiving element is located on the opposite side of the condensing lens with respect to the first light receiving element.
further comprising a light control element that guides the laser beam reflected by the measurement object toward the condensing lens,
The scanning distance measuring device according to any one of claims 1 to 5, wherein the light control element is disposed at a position shifted in a direction orthogonal to the optical axis of the condenser lens.
7. The scanning distance measuring device according to claim 6, wherein the second light receiving element is located on the opposite side of the light control element with respect to the optical axis.
8. The light control element according to claim 6, wherein the light control element is disposed at a position offset from the optical axis of the condenser lens in a direction parallel to a fast axis of the laser light emitted from the laser light source. Scanning distance measuring device.
The scanning type according to any one of claims 1 to 8, wherein the processing circuit controls the laser light source so that the amount of laser light is reduced when the object to be measured exists within the distance measurement area. Ranging device.
Scanning according to any one of claims 1 to 8, wherein the processing circuit controls the laser light source so that the radiation density of the laser light is reduced when the measurement target exists within the distance measurement area. Type ranging device.