JPH07218633A - Distance measuring equipment - Google Patents

Abstract

PURPOSE:To realize measurement over a wide range without requiring a plurality of optical projection systems by rotating a pair of optical wedges having similar profile in the opposite directions at a same rotational speed thereby projecting the the light while deflecting linearly and continuously over a wide range. CONSTITUTION:A laser light pulse from a laser diode 1 is condensed through a lens 5 and enters into an optical wedge 6. On the other hand, a measurement control circuit 33 feeds a motor driver 34 with a command for driving a motor 10 which rotates two optical wedges 6a, 6b having similar profile in the opposite directions at a same angular speed. The luminous flux of laser light pulse is deflected when passing through the wedge 6 and leaves the wedge 6 while altering the irradiating direction. Reflected wave impinging on a lens 11 is subjected to photoelectric conversion through a light receiving element 12 and electrically processed through a light receiving detector 32. A measuring circuit 33 then operates the distance which is presented on a display. The pair of wedges 6a, 6b rotating in the opposite directions directs the luminous flux in one direction, e.g. horizontal or vertical direction with respect to the incident optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device. More specifically, a distance measurement that measures the distance to the object to be measured by emitting a light pulse to the object and measuring the round-trip time of the light until the reflected light from the object is received. It relates to the device.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand in various fields to obtain distance information by mounting a distance measuring device on a moving object for the purpose of improving safety and automation. For example, a distance measuring device is mounted on a robot, an automobile, or a train to prevent collision of these moving objects, or a distance measuring device is mounted on a carrier vehicle used in a factory to control the stop position of the carrier vehicle. It is used to As such a distance measuring device, a device that emits pulsed laser light from a light source to a measurement target, receives pulsed laser light reflected by the measurement target, and measures the distance to the distance measurement target is widely used. ing.

When detecting an object to be measured such as an obstacle in front, it is required to widen the irradiation range of the pulsed laser light depending on the situation and detect the obstacle over a wide range to ensure safety. is there. To expand the light irradiation range and detect the measurement object over a wide range, change the irradiation direction of the pulsed laser light sequentially.
Although it is conceivable to provide a plurality of light sources, it is necessary to provide a plurality of optical systems for converging the luminous fluxes emitted from the respective light sources to a predetermined beam angle, which causes a problem of increasing the size of the apparatus.

To solve this problem, Japanese Patent Laid-Open No. 61-
Japanese Patent No. 259185 discloses a technique for solving this problem by installing a plurality of light sources. This has a plurality of light sources 41 that emit light as shown in FIG. 6 and one lens system 43 that bends the light emitted from the plurality of light sources in a predetermined direction and collects the light. Is a combination of an integrated laser diode in which a plurality of laser diodes are integrated on one chip and one optical system without increasing the size of the device.

Further, Japanese Laid-Open Patent Publication No. 5-52938 discloses a technique for solving this problem by changing the irradiation direction of laser light. As shown in FIG. 7, a disc-shaped optical wedge 3 having a plurality of wedge angles is rotatably arranged in the optical path between a laser diode and a convex lens that focuses the laser light from the laser diode. .

[0006]

However, Japanese Unexamined Patent Application Publication No. 61-2
The technique described in Japanese Patent No. 59185 has a problem in that the integrated laser diode itself is expensive and is not general, and it is difficult to inexpensively configure the device using the integrated laser diode.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 5-52938, irradiation can be performed in a wide range, but the irradiation direction is discrete, and continuous one-dimensional scanning is impossible. There was a problem.

In view of the above problems, the present invention provides a distance measuring device that uses one light source and one projection optical system and is capable of linearly and repeatedly changing the detection range to measure the distance. With the goal.

[0009]

The present invention comprises a light projecting optical system for projecting light from a light source onto an object, and a light receiving optical system for allowing the projected light to be reflected and incident on the object. Then
In the distance measuring device for measuring the distance to the object by measuring the time from the light is projected to being received,
The projection optical system is provided with two optical wedges having the same wedge angle and deflecting the light from the light source and rotating in opposite directions at the same angular velocity. Projection light deflecting means that repeatedly changes in a straight line, and two optical wedges that are provided in the light receiving optical system and that deflect the incident light and rotate in opposite directions at the same angular velocity and that have the same wedge angle One or both of the incident light deflecting means for repeatedly changing the incident angle of the incident light on a straight line.

It is desirable that both the projection light deflecting means and the incident light deflecting means are provided, and the both are deflected so that they are projected and incident in the same direction in synchronization with each other.

It is preferable that the projection light deflection means repeatedly and horizontally change the projection light in a straight line.

It is preferable that the incident light deflecting means repeatedly changes the incident angle of the incident light horizontally in a straight line.

[0013]

The two optical wedges having the same shape are provided in the light projecting optical system or the light receiving optical system and rotate in opposite directions, and the projected light or the reflected light is linearly deflected over a wide range to project or receive the light.

Although there is one light source and one projection optical system, since two optical wedges having the same shape rotate in opposite directions, the projected light or reflected light is linearly deflected over a wide range, A wide range of linear distance measurement areas can be secured.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The pulsed laser diode 1 is a light source that emits a laser light pulse. The lens 5 is a projection optical system that focuses the emitted light beam of the laser light pulse at a predetermined beam angle and projects it. In front of the lens 5, a pair of optical wedges 6a and 6b form an optical wedge 6 as an optical system so as to intersect the luminous flux of the laser light pulse. The optical wedges 6a and 6b have the same wedge angle θ and are supported by the supporting metal member 7, respectively. A gear 8 is provided on the outer periphery of the supporting hardware 7.
Is engraved. A gear 9 is provided so as to mesh with the gear 8, and the support metal 7 is rotatably supported by the gear 8 and the gear 9. The gear 9 is coaxially engaged with the motor 10, the rotation of the motor 10 is transmitted to the support metal 7 through the gear 9 and the gear 8, and the optical wedges 6a and 6b can rotate in opposite directions at the same angular velocity. There is.

The lens 11 forms a light receiving optical system for receiving a laser light pulse reflected from an object (not shown), and the light receiving element 12 photoelectrically converts the laser light pulse into an electric signal. A background light cut filter 13 that extracts only necessary light is inserted between the lens 11 and the light receiving element 12.

The pulse generator 31 is a driver circuit for outputting a signal for driving the pulse laser diode 1, the light receiving detector 32 is a pulse detecting circuit for detecting reflected pulsed light, and the measurement control circuit 33 is a pulse generator 31 and a light receiving detector. A measurement circuit 33 that controls 32, calculates the distance by measuring the time difference between the signals output by both, a motor driver 34 is a driver circuit that drives the motor 10 according to a command from the measurement control circuit 33, and a display 35 is measurement control. The distance value calculated by the circuit 33 is displayed.

Next, the operation will be described. When a laser light pulse is emitted from the laser diode 1 by a signal from the pulse generator 31 according to a command from the measurement control circuit 33, the light is focused by the lens 5 and then the optical wedge 6
Incident on. On the other hand, a signal is output from the motor driver 34 in response to a command from the measurement control circuit 33, the motor 10 is driven, and the optical wedges 6a and 6b rotate in opposite directions at the same angular velocity. The light flux of the laser light pulse projected from the lens 5 is deflected when passing through the optical wedge 6, and is emitted while changing the irradiation direction. Light reflected from an object (not shown) and incident on the lens 11 passes through the background light cut filter 13 and is received by the light receiving element 12. After photoelectric conversion, electric processing is performed by the photodetector 32,
The signal is input to the measuring circuit 33, the distance is calculated from the measured time difference, and the obtained distance value is displayed on the display unit 35.

Next, the effect of the optical wedge 6 formed of the optical wedges 6a and 6b which rotate in opposite directions will be described. When the light beam enters the optical wedge 6a, the light beam is deviated to the thick side of the wedge by an angle φ, as shown in FIG. φ has the following relationship with the wedge angle θ. φ≈ (n−1) θ, where n is the refractive index of the optical wedge When this optical wedge 6a is rotated with respect to the optical axis,
The light flux becomes a rotating light flux deviated by a certain angle φ with respect to the optical axis.

When the pair of optical wedges 6a, 6b having the same wedge angle are rotated in opposite directions, the declination angle is continuously in the plane including the incident optical axis between approximately -2φ and 2φ. It changes back and forth. That is, it is possible to obtain an optical system having a deviation angle that continuously reciprocates on a straight line. This state is shown in FIG.

A wedge 6 composed of a pair of optical wedges 6a and 6b that rotate in opposite directions is disposed after the light-sending lens 5 and is continuously rotated by the motor 10, so that the light-sending light beam is transmitted with respect to the incident optical axis. It is repeatedly scanned in one vertical direction. If this one direction is set to be the horizontal direction, horizontal scanning becomes possible, and if it is set to the vertical direction, vertical scanning becomes possible. In this case, the scanning range can be set arbitrarily by selecting the declination of the optical wedge 6, and the scanning speed can be set arbitrarily by selecting the rotation speed of the motor 10 and the gear ratio of the gears 9 and 8. be able to.

Next, another embodiment will be described with reference to FIG. Detailed description of the same or similar points to the above-described embodiment will be omitted. An optical wedge 14 as an optical system formed of a pair of optical wedges 14a and 14b is installed across the front of both the lens 5 and the lens 11.
The optical wedges 14a and 14b have the same wedge angle and are rotatable in opposite directions at the same angular velocity. Therefore, the reflected light is deflected in synchronization with the deflection of the projected light, so that the detection efficiency is good and the disturbance of other light is reduced. In this embodiment, although the diameter of each optical wedge is increased, both light projection and light reception can be performed without increasing the number of parts.

Still another embodiment will be described with reference to FIG. Detailed description of the same or similar points to the above-described embodiment will be omitted. A pair of optical wedges 15 in front of the lens 5
A pair of optical wedges 16a and 16b are installed in front of a and 15b and the lens 11. Optical wedge 15
a, 15b, 16a and 16b have the same wedge angle. The rotation of the motor 10 is transmitted through the gears 9 and 8, and the optical wedge 15a and the optical wedge 15b are rotatable in opposite directions at the same angular velocity.

The rotation of the motor 10 includes a gear 8 meshing with the gear 9, a gear 17 meshing with the gear 8, a gear 18 coaxial with the gear 17, a gear 19 meshing with the gear 18, and a gear 20 coaxial with the gear 19. The optical wedge 16a and the optical wedge 16b are transmitted through the gear 21 that meshes with the gear 20, and the optical wedge 16a and the optical wedge 16b have the same angular velocity in opposite directions and the optical wedge 15
It is rotatable in synchronization with the rotation of a and the optical wedge 15b.

Therefore, since the reflected light is deflected in synchronization with the deflection angle of the projected light, the detection efficiency is good and the disturbance of other light is reduced. In this embodiment, the diameter of each optical wedge is equal to the lens 5
Alternatively, the size can be reduced to about the same as the diameter of the lens 11.

It goes without saying that the optical wedge used in each of the embodiments is not limited to the one having a geometrical shape of a wedge shape, and an optical wedge having a variable refractive index is included.

In each of the embodiments, the projection light is normally deflected in the horizontal direction so that the distance can be measured in a wide area spread in the horizontal direction, and a wide detection range in the vertical direction is required. Can deflect the projected light in the vertical direction to expand the area in the vertical direction and measure the distance.

As described above, in each embodiment, continuous scanning can be performed in a wide range without using a plurality of laser diodes or optical systems, and a special light emitting element or the like is not required. Therefore, the device can be constructed at low cost.

[0029]

In the distance measuring device of the present invention, two optical wedges of the same shape provided in the light projecting optical system or the light receiving optical system rotate at the same rotational speed opposite to each other. Therefore, although there is only one light source and one projection optical system, the projection light is linearly and continuously deflected over a wide range to scan and project. Also, there is one light receiving optical system and one light receiving element, respectively. Light is linearly and continuously deviated in a wide range and received. Since the two are synchronized, the reflected light from the object can be measured in a wide range with less disturbance light.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram for explaining a deviation angle of an optical wedge that constitutes an embodiment of the present invention.

FIG. 3 is a diagram illustrating scanning by an optical wedge that constitutes an embodiment of the present invention.

FIG. 4 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 5 is a block diagram showing the configuration of still another embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional example.

FIG. 7 is a perspective view of a disc-shaped optical wedge used in a conventional example.

[Explanation of symbols]

1 ... Pulse laser diode 5 ... Lens 6 ... Optical wedge 6a, 6b, 14a, 14b, 15a, 15b, 16
a, 16b ... ・ Optical wedge 7 ・ ・ ・ ・ ・ ・ Supporting metal 8 ・ ・ ・ ・ Gear 9 ・ ・ ・ ・ Gear 10 ・ ・ ・ ・ Motor 11 ・ ・ ・ ・ Lens 12 ・ ・ ・ ・ ・ ・ Light receiving element 13 ・ ・..Background light cut filters

Claims (4)

[Claims] 1. A light projecting optical system for projecting light from a light source onto a target object, and a light receiving optical system for allowing the projected light to be reflected by the target object for incidence, wherein the light is projected. In the distance measuring device for measuring the distance to the object by measuring the time from receiving light, provided in the projection optical system,
Projection light deflection that deflects the light from the light source and has two optical wedges having the same wedge angle that rotate in opposite directions and at the same angular velocity, and repeatedly changes the emission angle of the projected light on a straight line Means and two optical wedges provided in the light receiving optical system for deflecting the incident light and rotating in opposite directions at the same angular velocity and having the same wedge angle. A distance measuring device, characterized in that it is provided with either one or both of incident light deflecting means for repeatedly changing the coming angle on a straight line. 2. The projection light deflecting means and the incident light deflecting means are both provided, and both are synchronized with each other and deflected so as to project and enter in the same direction. Distance measuring device. 3. The projection light deflecting means repeatedly changes the projected light horizontally in a straight line.
Alternatively, the distance measuring device according to item 2. 4. The distance measuring device according to claim 1 or 2, wherein the incident light deflecting means repeatedly and horizontally changes an incident angle of the incident light in a straight line.