JPH06281740A - Distance measuring instrument - Google Patents

Abstract

PURPOSE:To easily align the optical axis of diodes with each other at the time of mounting a distance measuring instrument on a vehicle by providing a visible light emitting means in coincidence with the emitting optical path of pulsed light for measuring distance. CONSTITUTION:An infrared laser diode 2 emits infrared rays having a wavelength of about 900nm and the infrared rays are converged into a prescribed angle Qt through a convex lens 3 after passing through a dichroic mirror 101 which is set at 45 deg. against the optical axis of the infrared rays and are cast on an object as sending-out rays Lt. A red light emitting diode 102 emits visible light rays having a wavelength of about 660nm and the visible light rays are directed to the lens 3 after they are reflected by the mirror 101 and changing their optical path by 90 deg.. Therefore, the light rays emitted form the diode 102 are sent to the object along (in coincidence with) the optical axis of the infrared rays emitted from the diode 2. When the diode 102 is set at the focal distance of the lens 3 so as to converge the visible light rays passed through the lens 3 into very thin light rays, the optical axes of the diodes 2 and 102 can be easily aligned with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention sends light to an object,
The present invention relates to a distance measuring device that detects the reflected light and detects the distance to an object, and particularly relates to a distance measuring device that can easily perform its optical axis alignment when the device is mounted on a vehicle or the like. .

[0002]

2. Description of the Related Art A pulsed light such as a laser beam is sent toward an object, and the reflected pulsed light reflected by the object is received by an optical system such as a convex lens or a concave mirror and pulsed. A distance measuring device that measures a distance to an object by detecting a delay time from light transmission to light reception is already known. FIG. 5 is a block diagram showing an example of a conventional distance measuring device. 1 is a light-transmitting lens barrel, 2 is an infrared laser diode attached to the bottom of the light-transmitting lens barrel, and 3 is an infrared laser diode. It is a convex lens for converging the emitted pulsed light at a predetermined angle θt to form the transmitted light Lt, which is attached to the opening end of the lens barrel 1. The infrared laser diode 2 is arranged so as to be on the optical axis of the convex lens 3.

Further, in FIG. 5, reference numeral 4 is a light-receiving lens barrel, and 5 is a photodiode attached to the bottom of the light-receiving lens barrel 4. Reference numeral 6 denotes a convex lens for irradiating an object (not shown) with the transmitted light Lt and condensing the reflected light Lr, which is attached to the opening end of the light-receiving lens barrel 4. The photodiode 5 is on the optical axis of the convex lens 6 and the convex lens 6
It is located at the almost focal point. Reference numeral 7 is a filter for transmitting the reflected light Lr and cutting other visible light.
It is installed between the photodiode 5 and the convex lens 6. Reference numeral 8 denotes a controller. The controller 8 includes a pulse generator 9 for pulse-driving the infrared laser diode 2, a pulse detector 10 for amplifying and shaping the light reception output signal of the photodiode 5, and these pulse generators. 9 and a signal processing circuit 11 which is connected to the pulse detector 10 and calculates the distance to the object from the delay time from the transmission of the pulsed light to the reception of the pulsed light. 12 is a display device,
The distance information obtained as described above is displayed as concrete numbers or graphs.

Next, the operation principle of the conventional distance measuring device is shown in FIG.
Described in. FIG. 6A shows a drive pulse of the sending light Lt sent from the light sending lens barrel 1. The pulse width tw (about 20) is generated by the pulse generator 9 provided in the controller 8.
μs) and the period tp (about 100 μs) to drive the infrared laser diode 2. FIG. 6B shows a light receiving pulse that receives the reflected light Lr from the object. A delay time t occurs between these light-transmitting pulse and light-receiving pulse depending on the distance to the object. Since this delay time t is a time difference corresponding to the round trip distance to the object, the distance to the object is R
given that,

R = c · t / 2

[0006] is required. Here, c is the propagation velocity of the laser light, and c = 3 × 10 ⁸ m / s.

The emission wavelength of the infrared laser diode 2 is about 900 nm, which is invisible light, because a large output is obtained, no dazzling is given to an object, and it is not perceived that distance measurement is being performed. Infrared light is used.
Regarding the light transmission angle θt, when this distance measuring device is mounted on a vehicle and the distance to the vehicle traveling ahead is measured, the distance 1
The light transmission angle θt is set to about 2 ° so that the detection range in the lateral direction at the position of 00 m is about 3.5 m corresponding to the road width.

[0008]

When a conventional distance measuring device is mounted on a vehicle, its optical axis must be exactly aligned with the axis of the vehicle, but the pulsed light to be transmitted is infrared light which is invisible light. Since it is light and the light-transmitting angle θt is very narrow, around 2 °, this optical axis alignment requires repeated temporary mounting and correction work several times, which is very difficult for optical axis alignment. There was a problem that it took time.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a distance measuring device which can easily align its optical axis when the distance measuring device is mounted on a vehicle. There is.

[0010]

A distance measuring device according to a first aspect of the present invention comprises a visible light irradiating means for irradiating visible light in conformity with a light transmission path of pulsed light for measuring a distance. It is a thing.

According to a second aspect of the present invention, in the distance measuring device, a visible light source that emits visible light is provided in the light sending lens barrel, and the visible light source and the light sending optical system in the light sending lens barrel are provided. In the meantime, a mirror that transmits either one of infrared light and visible light but reflects the other is provided with a mirror for matching the light-transmitting optical path of the infrared pulsed light with the light-transmitting optical path of the visible light. It is provided.

According to a third aspect of the present invention, the distance measuring device is provided with visible light irradiating means for transmitting visible light in the light transmitting lens barrel so as to coincide with the light transmitting optical path of infrared pulsed light. A selection means for selectively transmitting light and infrared pulsed light to the object from the light-transmitting lens barrel is provided.

Further, a distance measuring device according to a fourth aspect of the present invention is one in which the visible light source according to the second or third aspect is installed at the focal position of the light transmitting optical system in the light transmitting lens barrel.

[0014]

According to the distance measuring apparatus of the first aspect of the present invention, the visible light sent by the visible light irradiating means in conformity with the light sending path of the pulsed light can be visually observed, so that the optical axis is aligned. Can be done while looking at this visible light.

Further, according to the distance measuring device of the second aspect of the present invention, by using a mirror having a characteristic of transmitting either one of infrared light and visible light, but reflecting the other, red light can be obtained. The optical axes of external light and visible light can be structurally easily matched.

According to the distance measuring device of the third aspect of the present invention, only the visible light can be sent by the selecting means when the optical axis is aligned, and the infrared pulsed light is used when the distance is measured. It is possible to send only light.

Further, according to the distance measuring apparatus of the fourth aspect of the present invention, visible light can be made to coincide with the light-transmitting optical path of the pulsed light, and can be converged to be transmitted.

[0018]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1A denotes a light-sending lens barrel, and this light-sending lens barrel 1A corresponds to the light-sending lens barrel 1A shown in FIG.
Another cylindrical body 100b is vertically attached to the upper end of the leading end of 00a to communicate the inside. These cylinders 100
Each of a and 100b has a bottom portion 11 and a bottom portion 13. Reference numeral 2 is an infrared laser diode attached to the bottom of the cylindrical body 100a for emitting infrared pulsed light having an emission wavelength of about 900 nm. Reference numeral 3 denotes a convex lens for converging the infrared pulsed light of the infrared laser diode 2 at a predetermined angle .theta.t into the outgoing light Lt, which is attached to the opening end of the light sending barrel 1A. The infrared laser diode 2 is arranged on the optical axis of the convex lens 3. Reference numeral 101 denotes a dichroic mirror arranged so as to intersect the optical axis of the convex lens 3 at an angle of 45 °. When the light incident from the convex lens 3 is reflected by the dichroic mirror 101, the bottom portion 13 of the cylindrical body 100b is formed. It is installed to face.

As shown in FIGS. 2A and 2B, the dichroic mirror 101 transmits almost all infrared light having a wavelength of about 750 nm or more, and almost transmits visible light having a wavelength of less than that. It has a characteristic to reflect most. Therefore, the infrared light and the visible light can be sent out in the same direction by making the infrared light and the visible light whose optical paths have an angle of 90 ° with each other.

Reference numeral 102 denotes a visible light source attached to the bottom portion 13 of the cylindrical body 100b of the light-transmitting barrel 1A, for example, a red light emitting diode for emitting high-luminance red visible light, which is installed at the focal position of the convex lens 3. There is. 4 is a light-receiving lens barrel,
The structure of the light-receiving lens barrel 4 is exactly the same as that of the conventional device described in FIG.

Next, the operation of the first embodiment will be described. In FIG. 1, a cylindrical body 10 that is one bottom of the light-transmitting barrel 1A.
Since the infrared laser diode 2 attached to the bottom portion 11 of 0a emits infrared light having a wavelength of about 900 nm, as described with reference to FIG. 2, the dichroic mirror attached at an angle of 45 ° with this optical axis. After passing through 101, the convex lens 3 converges the light at a predetermined angle θt and irradiates the object as the outgoing light Lt, as in the conventional apparatus. On the other hand, since the red light emitting diode 102 installed so as to emit light having an optical axis intersecting with the optical axis of the light emitted by the infrared laser diode 2 at 90 ° is visible light having a wavelength of about 660 nm, the dichroic mirror 101 is used. The light is reflected, the optical path is bent by 90 °, and the light enters the convex lens 3. Therefore, the light emitted from the red light emitting diode 102 is sent toward the object along (coincident with) the optical axis of the pulsed light emitted from the infrared laser diode 2.

That is, since the red light-emitting diode 102 is installed at the focal position of the convex lens 3 as described above, the visible light that has passed through the lens 3 becomes a light beam that is extremely finely focused and serves as the guide light Lg. , Outgoing light L
Light is emitted in the same direction as t.

FIG. 3 is a diagram showing the sending state of the sending light Lt and the guide light Lg sent from the distance measuring device of the first embodiment, and FIG. 4 is a drawing showing the sending light Lt sent to the object and the guide. It is a figure which shows the mode of light Lg, and when it corresponds to the case where the optical axis in FIG. The outgoing light Lt has a divergence angle of about 2 ° as described above, but since the guide light Lg is installed at the focal position of the convex lens 3, it becomes much narrower than the outgoing light Lt as described above, and the red light is red. If the optical axes of the outer laser diode 2 and the lens 3 of the red light emitting diode 102 are made to coincide with each other, the guide light Lg can be present at the center of the transmitted light Lt as shown in FIG. Since this guide light Lg is red visible light, it is possible to easily align the center of the transmitted light Lt with the object by projecting it on the object.

As described above, the guide light Lg is used for the optical axis adjustment work.
However, the infrared laser diode 2, which is a light source for distance measurement, does not emit light during irradiation of the guide light Lg. Conversely, the transmitted light Lt during distance measurement
The circuit is set so that the guide light Lg is not emitted during the transmission. This avoids extra power consumption, and the driving of the infrared laser diode 2 is stopped during the optical axis adjustment work because the sending light Lt is unnecessary during the optical axis adjustment work, and the safety to the human body is improved. It is also from the aspect.

Example 2. In the above embodiment, the dichroic mirror 101 that transmits infrared light and reflects visible light.
Has been arranged at an angle of 45 ° on the center line connecting the center of the convex lens 3 and the infrared laser diode 2, and the visible light source has been installed facing the mirror at the position of 90 ° with the infrared laser diode 2. Contrary to the first embodiment, the characteristics of the dichroic mirror 101 are such that visible light is transmitted but infrared light is reflected. Even if the positions of the infrared laser diode 2 and the red light emitting diode 102, which is a visible light source, are reversed. The same effect is obtained. Further, although the dichroic mirror 101 is used as the mirror in the above embodiment, a half mirror may be used as long as the reduction in efficiency is allowed. Further, although the red light emitting diode 102 is used as the light source of the guide light Lg, other visible light sources may be used as a matter of course.

[0026]

As described in detail above, the distance measuring apparatus according to the first aspect of the present invention irradiates visible light by irradiating visible light in conformity with the light transmission path of pulsed light for measuring distance. Since the means is provided, it is possible to perform the optical axis alignment work when mounted on the vehicle while visually confirming it by projecting the visible light as a guide light to the object, so that there is an effect that it can be performed very easily.

According to a second aspect of the present invention, in the distance measuring device, a visible light source that emits visible light is provided in the light-sending lens barrel, and the visible light source and the light-sending optical system in the light-sending lens barrel are provided. In the meantime, a mirror that transmits either one of infrared light and visible light but reflects the other is provided with a mirror for matching the light-transmitting optical path of the infrared pulsed light with the light-transmitting optical path of the visible light. Since it is provided, in addition to the effect of the above-mentioned claim 1, there is an effect that the configuration can be easily obtained.

According to a third aspect of the present invention, the distance measuring device is provided with visible light irradiating means for irradiating visible light on the light-transmitting lens barrel so as to match the light-transmitting optical path of the infrared pulsed light. Since the selection means for selectively transmitting the infrared light and the infrared pulsed light to the object from the light-transmitting lens barrel is provided, it is possible to avoid excessive power consumption and to perform infrared laser diode operation during optical axis adjustment work. By stopping the driving of No. 2, there is an effect that the safety for the human body can be achieved.

Further, a distance measuring device according to a fourth aspect of the present invention comprises the visible light source according to the first to third aspects,
Since it is installed at the focal position of the light-sending optical system in the light-sending lens barrel, visible light can be focused and sent, and thus the optical axis adjustment work can be performed more easily and accurately.

[Brief description of drawings]

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

FIG. 2 is a diagram showing characteristics of a dichroic mirror used in the present invention.

FIG. 3 is a diagram showing the states of transmitted light and guide light according to the first embodiment of the present invention.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is an overall configuration diagram of a conventional distance measuring device.

FIG. 6 is a diagram illustrating a distance measuring principle.

[Explanation of symbols]

 1 Light-transmitting barrel 2 Infrared laser diode 3 Convex lens 101 Dichroic mirror 102 Red light emitting diode

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[Procedure amendment]

[Submission date] June 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

Example 2. In the above embodiment, the dichroic mirror 101 that transmits infrared light and reflects visible light.
Has been arranged at an angle of 45 ° on the center line connecting the center of the convex lens 3 and the infrared laser diode 2, and the visible light source has been installed facing the mirror at the position of 90 ° with the infrared laser diode 2. Contrary to the first embodiment, the characteristics of the dichroic mirror 101 are such that visible light is transmitted but infrared light is reflected. Even if the positions of the infrared laser diode 2 and the red light emitting diode 102, which is a visible light source, are reversed. The same effect is obtained. Further, although the dichroic mirror 101 is used as the mirror in the above embodiment, a half mirror may be used as long as the reduction in efficiency is allowed. Further, although the red light emitting diode 102 is used as the light source of the guide light Lg, other visible light sources such as a red (visible) semiconductor laser may be used as a matter of course.

Claims (4)

[Claims] 1. A method for transmitting pulsed light to a target object, detecting reflected light of the pulsed light from the target object, and based on the time from the irradiation of the pulsed light to the detection of the reflected light. A distance measuring device for detecting a distance to the target object, comprising a visible light irradiating means for irradiating visible light in conformity with the light transmission path of the pulsed light. 2. A light-transmitting barrel comprising a light source that emits infrared pulsed light, and a light-transmitting optical system that focuses the light source and sends it to an object.
The focused infrared pulsed light is provided with a light receiving lens barrel that collects the reflected light reflected by hitting the target object, and the distance to the target object is determined by the delay time from the transmission of the infrared pulsed light to the reception of the infrared pulsed light. In the distance measuring device for measuring, a visible light source that emits visible light is provided in the light-sending lens barrel, and infrared light and visible light are provided between the visible light source and the light-sending optical system in the light-sending lens barrel. A distance characterized in that a mirror is provided which has a property of transmitting one of the two and transmitting the other, and the other has a property of reflecting the light transmission optical path of the infrared pulsed light and the light transmission optical path of the visible light. measuring device. 3. A light-sending lens barrel comprising a light source for emitting infrared pulsed light, and a light-sending optical system for focusing the light source and sending it to an object.
This focused infrared pulsed light is provided with a light-receiving lens barrel that collects the reflected light reflected by hitting the object to be measured, and the delay time from the transmission of the infrared pulsed light to the reception of the infrared pulsed light In a distance measuring device for measuring a distance, the light-sending lens barrel is provided with visible light irradiating means for irradiating visible light in conformity with the light-transmitting optical path of the infrared pulsed light, and the visible light and the infrared pulsed light. A distance measuring device comprising a selecting means for selectively transmitting light to the object from the light transmitting lens barrel. 4. The distance measuring device according to claim 2, wherein the visible light source is installed at a focal position of the light sending optical system in the light sending lens barrel.