JPH1164490A - Light wave range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light wave range finder in which a motor can be selected from an optimal range while enhancing the performance and reducing the cost without requiring a special motor which determines the absolute rotational position by itself. SOLUTION: The light wave range finder for measuring the distance to an object by making a switch between a range finding light state for projecting the light from a light source to the object and a reference light state for projecting the light from a light source to a reference light path 4b through the light path selection opening 1a in a light shielding plate 1 comprises means for discriminating between the range finding light state and the reference light state by detecting the position of the light path selection opening 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightwave distance measuring device which irradiates a lightwave toward an object, receives reflected light thereof, and measures the distance to the object.

[0002]

2. Description of the Related Art Conventional lightwave distance measuring devices include a continuous wave method and a pulse wave method. In the continuous wave method, light is transmitted as a wave whose intensity is continuously modulated, and reflected light from a target is received. Then, the phase of the received continuous wave is compared with the phase of the transmitted continuous wave to determine the distance from the lightwave distance measuring device to the target. On the other hand, in the pulse wave method, pulse light having a narrow pulse width is transmitted, and reflected pulse light from a target is received. Then, the travel time of the pulse light from light transmission to light reception is measured, and the distance to the target is obtained from the pulse light travel time.

[0003] The optical path in which light travels in a lightwave distance measuring device includes a distance measuring optical path and a reference optical path. The ranging optical path refers to an optical path from when light from a light emitting unit is irradiated on a target to when light reflected from the target is received by a light receiving unit. On the other hand, the reference optical path refers to an optical path that does not project light from the light emitting unit to the outside but passes through a path inside the device and causes the light receiving unit to receive the light.

[0004] The reference optical path is provided to remove an error in the measurement distance due to a temperature change or an aging change.
That is, in the lightwave distance measuring device, for example, the time detected in the electric circuit for converting the reflected light into the electric signal varies depending on the temperature. Therefore, the measurement error is removed by subtracting the measurement distance obtained from the reference light path from the measurement distance obtained from the distance measurement light path. Therefore, in the lightwave distance measuring device, it is necessary to switch between the distance measuring optical path and the reference optical path, and the light emitted by the light emitting unit is transmitted to the distance measuring optical path or the reference optical path by an opening provided in a light shielding plate described later. Can be switched.

FIG. 6 shows an example of the shape of a conventional light shielding plate 1.
The light shielding plate 1 is made of, for example, a substantially circular thin plate, and has two semicircular openings. An opening in the outer periphery of the light shielding plate 1 is an opening 1a for selecting a distance measuring optical path, and a rotation center 1c.
Is an opening 1b for selecting a reference optical path. As shown in FIGS. 6A and 6B, the light spot 11 projected from the light emitting unit of the lightwave distance measuring device is projected to a lower portion of the light shielding plate 1, so that the light shielding plate 1 is rotated to By changing the positions of the openings 1a and 1b, the distance measuring optical path and the reference optical path can be switched.

FIG. 6A shows a state where a distance measuring optical path is selected. The lower shaded portion of the light spot 11 is
The light passes through the distance measuring light path selecting opening 1a and is projected onto the distance measuring light path. On the other hand, FIG. 6B shows the light shielding plate 1 from the state of FIG.
Are rotated by 180 degrees, and the reference optical path is selected. The upper shaded portion of the light spot 11 passes through the reference light path selection opening 1b and is guided to the reference light path. In this case, switching between the distance measuring optical path and the reference optical path is performed by rotating a motor capable of determining the absolute rotational position of the light shielding plate 1 by 180 degrees.

[0007]

In the prior art as described above, in order to determine whether the light shielding plate 1 is in the distance measuring optical path state or the reference optical path state, the absolute rotation position is determined. It was necessary to use a distinguishable motor. However, since such motors are special, there are few types, and there is a limit in selecting an optimal motor in terms of performance and cost.

Therefore, an object of the present invention is to eliminate the need for a motor itself to use a special motor for determining the absolute rotational position.
It is an object of the present invention to provide a lightwave distance measuring device that allows a wide range of selection of an optimal motor, and that can improve performance and reduce costs.

[0009]

According to the present invention, there is provided a distance measuring light state for projecting light from a light source to an object to be measured, and projecting light from the light source to a reference optical path. In the lightwave distance measuring device that switches the reference light state and the light path selecting opening of the light shielding plate to measure the distance to the measurement object,
It is attained by providing a lightwave distance measuring device having an identification means for detecting the position of the light path selecting opening to identify whether the light is in the distance measuring light state or the reference light state. You.

That is, according to the present invention, the distance measuring light state and the reference light state can be distinguished without using a special position detecting section in the light-shielding plate and also as an optical path selecting opening. Therefore, there is no need for the motor itself to determine the absolute rotational position, so there is no need to use a special motor, and the range of selecting an optimal motor can be increased, and performance can be improved and cost can be reduced.

The object of the present invention is to move a light-shielding plate between a ranging light state in which light from a light source is projected onto an object to be measured and a reference light state in which light from the light source is projected on a reference optical path. In the lightwave distance measuring device for measuring the distance to the object to be measured by switching according to the above, the light shielding plate has a position detecting unit, and detects the position of the position detecting unit to determine whether or not the light is in the distance measuring light state. This is attained by providing a lightwave distance measuring device having identification means for identifying whether or not it is in a light state.

That is, according to the present invention, by providing the light-shielding plate with the position detector, the absolute rotation position of the light-shielding plate can be easily detected, and the structure of the light-shielding plate is simplified, and the cost is further reduced. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such embodiments do not limit the technical scope of the present invention.

FIG. 1 shows an optical arrangement of a lightwave distance measuring apparatus according to an embodiment of the present invention. The light emitted by the light emitting unit 3 is
The light is divided into a distance measuring optical path 4a and a reference optical path 4b by an opening provided in the light shielding plate 1. The light projected on the distance measuring optical path 4 a is reflected by the splitting prism 12, overlaps the visual axis 9 by the dichroic prism 7, and is projected outside through the objective lens 6.

The light projected to the outside is reflected by a target (not shown) and enters the objective lens 6 again.
The light entering the apparatus through the objective lens 6 is bent only by the dichroic prism 7 in terms of the distance measuring light, and is received by the light receiving unit 8. On the other hand, the light projected onto the reference optical path 4b by the opening of the light shielding plate 1 does not go out of the lightwave distance measuring device, but is directly received by the light receiving unit 8 via the optical fiber 13.

The light shielding plate 1 is rotated by a motor
The light emitted from the light emitting unit 3 rotated around the center c is distributed to the distance measuring optical path 4a by the distance measuring optical path selecting opening 1a and to the reference optical path 4b by the reference optical path selecting opening 1b.

A transmissive photo-interrupter 5 is provided on the upper outer peripheral portion of the light-shielding plate 1, and a projection 1 d described later of the light-shielding plate 1 is connected to a sensing portion 5 a of the transmissive photo-interrupter 5.
, The output signal of the transmissive photointerrupter 5 changes. Therefore, the transmission type photo interrupter 5
When a change occurs in the output signal, the light shielding plate 1
Is detected to be at the position of the rotation angle with.

FIG. 2 shows the shape of the light shielding plate 1 of the lightwave distance measuring apparatus according to the embodiment of the present invention. The shape of the light shielding plate 1 in FIG. 2 is a shape as viewed from the direction of the arrow 10 in FIG. The light shielding plate 1 is a substantially circular thin plate having a distance measuring light path selecting opening 1a, a reference light path selecting opening 1b, a rotation center 1c, and a projection 1d.

In FIG. 2, an opening 1a for selecting a distance measuring optical path.
And the reference optical path selecting opening 1b are each provided with a rotation center 1c.
And the opening 1a for selecting a distance measuring optical path is located at a position close to the outer periphery of the light shielding plate 1.
The reference optical path selection opening 1b is provided at a position near the rotation center 1c. The protrusion 1d is provided on the outer peripheral portion on the opposite side of the distance measuring optical path selecting opening 1a.

The selection of the optical path is performed as follows. When the rotation angle of the light shielding plate 1 is not fixed, the light shielding plate 1 is
To rotate in any direction. When the light shielding plate 1 is stopped when the projection 1d passes through the sensing portion 5a of the transmission type photo interrupter 5, the light shielding plate 1 is moved to the distance measuring optical path 4a.
Is selected. Further, by rotating the light shielding plate 1 by 180 degrees from this state, the optical path can be switched to the reference optical path 4b.

FIG. 2A shows a state in which the transmission type photointerrupter 5 detects the protrusion 1d and stops the rotation of the motor 2. Since the light spot 11 from the light emitting unit 3 is projected on the lower part of the light shielding plate 1, the hatched portion of the light spot 11 passes through the distance measuring optical path selecting opening 1 a and is guided to the split prism 12. . The rotation position of the light shielding plate 1 is the distance measuring optical path 4
a, the motor 2
Is rotated by 180 degrees, the reference optical path 4 shown in FIG.
b can be selected.

The motor 2 is a so-called stepping motor, and rotates by a fixed amount for each clock pulse. Therefore, if the number of clock pulses obtained by dividing 180 degrees by the fixed amount is given to the drive circuit of the motor 2, In addition, the light shielding plate 1 can be easily rotated by 180 degrees. Therefore, once the transmission type photo interrupter 5 detects the protrusion 1d and recognizes that the light shielding plate 1 is in the distance measuring optical path 4a state, thereafter, every time a predetermined number of clock pulses are output, the light shielding plate 1 is output. 1 rotates by 180 degrees, the reference optical path 4b state and the distance measuring optical path 4a.
The state is repeated alternately.

FIG. 3 shows a modification of the method for detecting the position of the light shielding plate 1. As described above, in the present embodiment, the projection 1b and the transmissive photointerrupter 5 are used as the position detection method of the light shielding plate 1, but it is not necessary to stick to this. For example, as shown in FIG. 3 (a), a reflective photointerrupter 31 and a projection reflector 30, as shown in FIG. 3 (b), a magnetic force sensor 33 and a magnetized portion 32, and as shown in FIG. A sensor that can uniquely detect the rotational position of the light shielding plate 1 such as the sensor 35 and the metal protrusion 34 or the transmission type photo interrupter 37 and the recess 36 as shown in FIG. 3D may be used.

Further, the shape of the light path selecting opening of the light shielding plate 1 is not limited to the present embodiment.
The distance measuring light path selecting openings 1a and the reference light path selecting openings 1b may be provided alternately at every 0 degree. In this case, 90
The optical path can be switched each time it rotates by one degree, the time required for selecting the optical path can be reduced, and high-speed ranging can be realized.

FIG. 4 shows the shape of the light path selecting opening of the light shielding plate 1 in such a case. In the present embodiment, the distance measuring optical path selecting opening 1a and the reference optical path selecting opening 1b
However, two sets are provided in an arc shape of approximately 90 degrees. FIG.
As in the case of (1), the aperture 1a for selecting the distance measuring optical path is
The reference light path selecting opening 1b is provided at a position near the rotation center 1c. Also, the protrusion 1
Two d's are provided outside the distance measuring optical path selecting opening 1a.

Therefore, when the transmission type photo interrupter 5 detects the protrusion 1d, as shown in FIG.
The distance measuring optical path 4a has been selected. In this state, if a predetermined number of clock pulses are input to the stepping motor 2, the light shielding plate 1 rotates 90 degrees, and the reference optical path 4b is selected as shown in FIG. 4B.

FIG. 5 shows an example in which the position detecting section of the light shielding plate 1 and the opening for selecting an optical path are also used. The light shielding plate 1 is the same as the 90-degree rotation type shown in FIG. 4 except that there is no projection. However, the position of the transmissive photointerrupter 5 is not at the top of the light shielding plate 1, but at a position 45 degrees to the right from the top.

As shown in FIG. 5 (a), when the transmission type photointerrupter 5 detects transmission from blocking when the rotation direction of the light shielding plate 1 is clockwise CW, the light shielding plate 1 is moved to the distance measuring optical path 4a. Is in the selected state. Further, as shown in FIG. 5A, when the transmission type photo-interrupter 5 detects blocking from transmission when the rotation direction of the light-shielding plate 1 is counterclockwise CCW, the light-shielding plate 1 becomes the distance measuring optical path 4a. Is in the selected state.

The transmission type photo interrupter 5 detects a state as shown in FIG.
The selection state of the reference optical path 4b can be detected. As described above, even if the light shielding plate 1 does not have a special position detecting unit such as a protrusion, the rotation angle can be detected also as the optical path selecting opening itself.

[0030]

As described above, according to the present invention, the provision of the position detecting section on the light shielding plate eliminates the need for the motor itself to determine the absolute rotational position, and eliminates the need for using a special motor. The range of choice of the motor can be varied, and performance improvement and cost reduction can be realized.

Further, according to the present invention, the distance measurement light state and the reference light state can be distinguished from each other without using a special position detecting section in the light shielding plate, because the light shielding plate can also be used as an optical path selection opening. The structure is simplified, and the cost is further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical arrangement of a lightwave distance measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a light shielding plate shape of the lightwave distance measuring device according to the embodiment of the present invention.

FIG. 3 is a diagram showing a modification of the method for detecting the position of the light-shielding plate according to the embodiment of the present invention.

FIG. 4 is a view showing a modification of the shape of the light-shielding plate opening according to the embodiment of the present invention.

FIG. 5 is a diagram showing an example in which a position detection unit and a light-shielding plate opening are also used according to the embodiment of the present invention.

FIG. 6 is a diagram showing a shape of a conventional light shielding plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield plate 1a Distance measuring optical path selecting opening 1b Reference optical path selecting opening 1c Rotation center 1d Projection 2 Motor 3 Light emitting unit 4a Distance measuring optical path 4b Reference optical path 5 Transmission type photo interrupter 5a Sensing unit 6 Objective lens 7 Dichroic prism 8 Receiver

Claims (3)

[Claims] A distance measuring light state in which light from a light source is projected on an object to be measured and a reference light state in which light from the light source is projected on a reference optical path are determined by an optical path selecting opening of a light shielding plate. In a light wave distance measuring device for switching and measuring a distance to the object to be measured, identification means for detecting a position of the light path selecting opening to identify whether the light is in the distance measuring light state or the reference light state. A lightwave distance measuring device comprising: 2. The apparatus according to claim 1, wherein the identification means detects a position of the optical path selection opening based on an output from the identification means obtained while rotating the light shielding plate. Lightwave distance measuring device. 3. A distance measuring light state in which light from a light source is projected onto an object to be measured and a reference light state in which light from the light source is projected on a reference optical path are switched by moving a light shielding plate to perform the measurement. In a light wave distance measuring device for measuring a distance to an object, the light shielding plate has a position detecting unit, and detects a position of the position detecting unit to determine whether the object is in the distance measuring light state or the reference light state. A lightwave distance measuring device comprising an identification means for identifying the distance.