JPH05197422A - Light-projecting/receiving device - Google Patents

Abstract

PURPOSE:To obtain a light projecting/receiving device having a means which can discriminate accurate external light and specified reflected light. CONSTITUTION:Light-projecting means 2 and 4 which execute scanning while emitting light with high directivity, a reflection means 5 reflecting incident light from the light-projecting means in the same direction as an incident direction, a light-receiving means 9 receiving incident light and a signal processing means 10 are provided. The signal processing means 10 consists of a storage means which executes scanning while emitting light of high directivity through the light-projecting means, and which previously stores the time-dependent characteristics of incident light and reflected light in the same direction as the incident direction, a detection means detecting the time-dependent characteristic of incident light, a comparison means comparing a value derived from the storage means with a value detected by the detection means, and an output means outputting the compared result. An output signal is outputted as output from the signal processing means when incident light which the light-projection means emit, whose directivity is high and which is scanned is received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is designed to scan highly directional light (predetermined light) emitted from a light projecting means and reflect the scanned incident light in the same direction as the incident direction. The present invention relates to a light projecting / receiving device capable of discriminating between predetermined light obtained and external light.

[0002]

2. Description of the Related Art Conventionally, as a position detecting device for a moving body such as an automobile or a carrier, the position detecting device for moving the moving body unmanned,
Confirm the current position of the moving body by using a light projecting / receiving device that projects laser light with high directivity to the retroreflectors installed at least at three or more locations on the ground and receives the reflected light from the retroreflector. There are various types of means for determining whether a light beam received by a light emitting / receiving device such as the remote information transmitting device is a predetermined reflected light or an external light other than that. Proposed.

Specifically, 1. 1. An optical filter such as a bandpass filter that can transmit only the vicinity of the wavelength of the used light, a directional filter that does not transmit light rays from directions other than the front direction to the light receiver, and 2. There is a polarization ratio processing means or the like that gives a special polarization ratio P / S to the light used, electrically detects the polarization ratio of the received light, and blocks light other than the normal polarization ratio.

[0004]

However, with the above-mentioned conventional means, regular reflected light and extraneous light cannot always be sufficiently discriminated from each other, and each has the following drawbacks. 1. The wavelength of the extraneous light includes the wavelength used by the light projector (for example, the light beam projected from the light projecting means is reflected by a reflector other than a predetermined reflector and enters the light receiving means).
In this case, it cannot be discriminated whether it is a predetermined light ray or extraneous light. 2. If the extraneous light is polarized by some means (for example, reflected) before entering the light receiving means and the polarization ratio of the regular ray to be received is satisfied, it is determined whether it is a predetermined ray or extraneous light. Can not. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above drawbacks and to provide a light projecting / receiving device having means capable of more accurately distinguishing external light from regular reflected light.

[0005]

In order to achieve the above object, in the light projecting / receiving device of the present invention, a light projecting means for scanning while emitting a highly directional light, and an incident light from the light projecting means. A reflecting means for reflecting the light in the same direction as the incident direction thereof,
It has a light receiving means for receiving incident light and a signal processing means, and the signal processing means scans while emitting light having a high directivity by the light projecting means, and the scanned incident light is in the same direction as the incident direction. Value derived from storage means for storing in advance the temporal characteristics of the reflected light obtained by reflecting the reflected light in a direction, detection means for detecting the temporal characteristics of the incident light, and storage means for storing the temporal characteristics of the reflected light. A comparison means for comparing both the values detected by the detection means for detecting the temporal characteristic of the incident light and an output means for outputting the comparison result, and the output from the signal processing means is the projection means. Provided is one which is configured to output an output signal when it receives high-directivity and scanned incident light emitted from an optical means.

[0006]

The projecting / receiving device of the present invention projects a beam of light having a high directivity projected by the projecting means by a desired method to project a beam of light in a wide area, and to provide an incident direction provided outside the device. The light beam projected from the light projecting unit (regular reflected light) reflected by the reflecting unit having the characteristic of reflecting in the same direction is received by the light receiving unit, and the time characteristic of the light beam received by the signal processing unit is stored in advance. By comparing the temporal characteristics stored in the means by the comparing means, it is determined whether the light ray is regular reflected light or extraneous light, and based on the discrimination result, only the regular reflected light or the extraneous light is output by the output means. The respective signals of are output.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of an embodiment of a light emitting and receiving device according to the present invention mounted on a moving body (not shown).
In the drawings, 1 is a light emitting / receiving device body, 2 is a light projecting means, 3 is a first mirror, and 4 is a hexagonal prism having a mirror surface formed on its side surface which can be rotated at a constant rotation speed by a motor (not shown). Polygon mirror, 5 is a retroreflector that reverses incident light by 180 degrees and retroreflects in the same direction as the incident direction, 6 is a polarizing plate that polarizes laser light, and 7 is a light beam (regular light that recurs through a retroreflector). Beam splitter which separates the reflected light of (1) or the laser light reflected by another reflector or the external light such as the sun rays directly incident on the polygon mirror from the outside into two polarization directions, 8 is a second mirror, and 9 is Light receiving means for receiving a light beam separated in two polarization directions and outputting a voltage (analog value) proportional to the light intensity of the received light beam, 10 is a signal processing means, 11 is an output of the light emitting and receiving device of the present invention. A CPU that controls the running state of the moving body based on signals (Hereinafter, simply referred to as CPU)
Are shown respectively.

FIG. 2 is a block diagram showing the internal structure of the signal processing means 10 of FIG. In the drawing, 12 and 13 are A / D converters that digitally convert the voltage (analog value) output from the light receiving means 9, and 14 is a polarization ratio that detects the polarization ratio of the received light and compares it with the polarization ratio stored in advance. A processing means, 15 is a temporal characteristic processing means for detecting a temporal characteristic of the received light beam and comparing it with a previously stored temporal characteristic, 16 is a temporal characteristic detecting means, 17 is a storing means, 18 is a comparing means, 19 Is a discriminating means for discriminating whether the received light is regular reflected light or extraneous light based on the processing result processed in the previous stage, and 20 is only regular reflected light or regular reflection based on the discrimination result of the discriminating means 19. The output means for outputting the signals of the light and the extraneous light in a distinguishable manner are shown.

FIG. 3 is a flow chart showing an example of signal processing by the signal processing means 10 in FIG. 1 (steps (S1 to S10) in parentheses for actions corresponding to this flow chart in the text below). Be noted).

As shown by the broken line in FIG. 1, the light projecting means 2 projects a light beam having a high directivity, such as a laser beam emitted from a semiconductor laser, which is narrowed down to an extremely small spot by a lens. , It passes through the first mirror 3 and is reflected on the surface of the polygon mirror 4. First
The mirror 3 has a feature that light rays coming from below are transmitted and light rays coming from above are reflected. At this time, the polygon mirror has axis 4
Since the light is reflected by the polygon mirror in a direction of an arrow A in the direction of arrow A at a constant number of revolutions around the ‘′, the light rays reflected by the polygon mirror are scanned in a fan shape by the action of the rotation of the polygon mirror, and a part thereof is scanned. Is incident on the retroreflector 5, for example, a corner cube. The light beam incident on the retroreflector 5 is polarized by the action of the polarizing plate 6 provided on the front surface of the retroreflector 5, and is retroreflected in the same direction as the incident direction by the action of the retroreflector 5. The retroreflected light ray (reflected light) is reflected again on the surface of the polygon mirror 4, and is separated into an S wave (transverse wave) and a P wave (longitudinal wave) by the beam splitter 7 via the first mirror 3. .. One of the separated light rays (reflected light) is directly input from the beam splitter 7, and the other is input to the light receiving means 9 via the second mirror 8. Further light receiving means 9
Then, each of the received light rays (reflected light) is converted into a voltage (analog value) and output to the signal processing means 10.

By the way, the light rays reflected from the outside of the apparatus by the polygon mirror 4 are not limited to the regular reflected light that recurs through the retroreflector 5, but the reflected light reflected by other reflectors or the polygon mirror directly from the outside. 4 also includes extraneous light such as sunlight incident on the S.
It is separated into waves and received by the light receiving means 9. Hereinafter, a light beam projected from the light projecting unit 2 is a laser beam, a laser beam projected from the light projecting unit 2 and retroreflected by the retroreflector 5 is a regular reflected light, and a laser beam projected from the light projecting unit 2 is retroreflected. Laser light retroreflected by reflectors other than the reflector 5 and light rays such as the sun directly incident on the polygon mirror 4 from outside are referred to as extraneous light, and the regular reflected light and extraneous light are collectively referred to as light rays. Shall be called.

The signal processing means 10 further converts the S wave and the P wave received by the light receiving means 9 and converted into a voltage (analog value) into digital signals by A / D converters 12 and 13, respectively. After that, the polarization ratio processing means 14 and the temporal characteristic processing means 15 perform processing. The levels of the S wave and P wave (digital value) converted by the A / D converters 12 and 13 are monitored by a level monitoring means (not shown) (S
1), the level is a desired value (hereinafter referred to as a threshold)
When the value exceeds, the level monitoring means outputs the polarization ratio processing means 14 and the temporal characteristic processing means 15 respectively (S).
2). The polarization ratio processing means 14 outputs the output signal (S) from the A / D converters 12 and 13 via the level monitoring means (not shown).
Wave, P wave) and input the maximum value S, P of S wave, P wave
Respectively, and after calculating the ratio P / S thereof, it is compared with a reference ratio P1 / S1 stored in advance, and the comparison result is discriminator 19
(S7). For example, the comparison result output to the discriminating means 19 may be set such that the reference ratio P1 / S1 is the polarization ratio (lower limit value) obtained by the polarization direction of the polarizing plate 6 provided on the front surface of the retroreflector 5. For example, P / S> P1 / S
If 1, the ray is a regular reflected light (B = 1),
Otherwise, the result is that it is an external light (B = 0) (S8).

Further, the temporal characteristic detecting means 16 inputs either one of the output signals (S wave, P wave) from the A / D converters 12 and 13 (whichever is acceptable) via the level monitoring means. After that, the detection of the temporal characteristic T of the light beam received by the light receiving means 9 is started (S3). The detection operation of the temporal characteristic T by the temporal characteristic detecting means 16 is performed by the A / D converter.
This is continued until the output level from the light receiving means 9 input to 12, 13 becomes lower than the threshold value (S4). Then, the temporal characteristic T of the light beam detected by the means 16 is compared with the reference temporal characteristic T ′ stored in the storage means 17 by the comparison means 18, and the comparison result is output to the discrimination means 19. (S5). The above-mentioned reference temporal characteristic T ′ may be any arbitrary temporal characteristic that the regular reflected light has,
For example, the laser beam scanned by the polygon mirror 4 may be the maximum one of the durations during which the laser beam is incident on the retroreflector 5. In this case, the duration of the regular reflected light, which is a temporal feature, is determined by the number of revolutions of the polygon mirror 4, the distance between the light emitting and receiving device body 1 (more precisely, the laser light reflecting portion of the polygon mirror) and the retroreflector 5. It depends on the size of the reflective portion of the retroreflector 5. The above-mentioned three conditions may be set so that the maximum value of the time is shorter than the incident time of the extraneous light that may enter the device body 1.

For example, when the external light incident on the apparatus main body 1 is sunlight, the incident time is 7500 rpm for the polygon mirror 4, the distance from the polygon mirror 4 to the light receiving means 9 is 100 mm, and the ordinary light receiving means 9 is also used. If the lens diameter of the signal receiving part provided inside is 20 mm, it is usually 126 × 10 ^-6 sec
Therefore, assuming that the distance that the apparatus body 1 comes closest to the retroreflector 5 is 1000 mm and the size of the reflecting portion of the retroreflector 5 is 10 mm, the regular reflection light duration, that is, the scanned laser light is the retroreflector. The maximum value of the time of incidence on 5 is always shorter than the time of incidence of extraneous light as determined by the following equation. From the rotation speed of 7500 rpm = 125rps, 125 (rps) × 360 ° = 45000 ° / sec ………… (1) Laser that does not enter retroreflector 5 from the position of the laser beam that started to enter retroreflector 5. Angle to light position (θ in Fig. 1) tan ^-1 {(10/2) / 1000} × 2 = 0.573 °… (2) Laser light scanned by (1) and (2) is retroreflector 5 0.573 / (45000 × 2) = 6.4 × 10 ^-6 (sec) The maximum value of the incident time on the retroreflector 5 is reflected by the retroreflector 5 and the regular reflection light is reflected. As the light is received by the light receiving means 9, the maximum value of the duration of the scanned laser light incident on the retroreflector 5 is stored in the storage means 17, and the maximum value is stored as the reference light receiving characteristic which is a temporal characteristic. If the time is T ′, the duration of time when the laser light scanned as described above is incident on the retroreflector 5 is always shorter than the time when external light is incident. If the comparison result (output to the discrimination means 19) of the light receiving time T of the light beam detected by the detection circuit 16 and the reference temporal feature T '(output to the discrimination means 19) is T'> T, the regular reflected light ( External light (A = 0) if A = 1) and T> T '
(S6).

The discrimination means 19 inputs the comparison results from the polarization ratio processing means 14 and the temporal characteristic processing means 15, respectively, and based on each comparison result, both of the two comparison results are normal reflected light (A = 1 and B = 1), it is determined that the reflected light is regular reflected light, and in other cases, it is external light, and the signal of the received light beam is output to the output means 20 based on the determination result (S9). At this time, the condition for the output means 20 to output the data is appropriately determined according to the CPU 11. For example, among the signals input to the output means 20, only the signal of the regular reflected light may be output. Alternatively, of the input signals, the signal of the regular reflected light and the signal of the other external light may be output in a distinguishable manner (S10).

In the projecting / receiving device of this embodiment, the laser light projected from the projecting means 2 is scanned by the polygon mirror 4 which can be rotated at a constant number of rotations. The range of incident light is wide, and the polarization ratio of the regular reflected light is retroreflected by the retroreflector 5, reflected again by the polygon mirror 4, and received by the light receiving means 9 by the actions of the mirrors 3, 8 and the beam splitter 7. Also, the light beam received by the light receiving means 9 is discriminated whether it is a regular reflected light beam or an external light beam based on the temporal characteristics, and the signal of the received light beam is output to the CPU 11. Has the effect. Although the present embodiment shows an example in which the polarization ratio processing means 14 is incorporated in the light emitting and receiving device of the present invention, the light emitting and receiving device of the present invention is not limited to this embodiment, and is independent.
Alternatively, it goes without saying that other signal processing means can be incorporated and used.

Further, in the present embodiment, the duration time during which the laser light scanned by the polygon mirror 4 is incident on the retroreflector 5 is defined as a temporal characteristic T, and the maximum value of the time stored in the storage means is 6.4 × 10 ^-6. Set sec and set the time (6.4 × 10 ^-6 se
Although an example is shown in which normal reflected light or extraneous light is discriminated by using c) as a reference light receiving time T ′, which is a temporal characteristic serving as a reference, this time T ′ is merely an example, and is actually used. However, even when external light is incident for a time shorter than that time (6.4 × 10 ⁻⁶ sec), the light projecting / receiving device of the present invention has the rotation speed of the polygon mirror 4 and the light projecting / receiving device body 1.
Since the reference time can be appropriately changed by appropriately changing the distance between the laser beam reflecting portion of the polygon mirror and the retroreflector 5 and the size of the reflecting portion of the retroreflector 5, there is no problem. Instead, it is possible to discriminate between regular reflected light and extraneous light with accuracy according to the environment of use.

Furthermore, the reference temporal characteristic is not limited to the time of incidence of the laser light scanned by the polygon mirror 4 on the retroreflector 5, and the laser having a high directivity for projecting from the projecting means 2 is used. It goes without saying that the light may be projected at a specific cycle and the speed element or the acceleration element at the rising and falling edges of the cycle may be used as a reference for the determination. The light emitting and receiving device of the present invention can be used by being applied to a moving object passage detecting device, a distance measuring device to a light reflector, a position confirming device of a moving object traveling unmanned, and the like.

[0019]

As described above, the light emitting and receiving device of the present invention has a light projecting means for scanning while emitting a highly directional light, and an incident light from the light projecting means in the same direction as the incident direction thereof. A reflecting means for reflecting the incident light, a light receiving means for receiving the incident light,
Reflection obtained by scanning while emitting light having high directivity by the light projecting means and reflecting the scanned incident light in the same direction as the incident direction thereof. The storage means for storing the temporal characteristic of light in advance, the detecting means for detecting the temporal characteristic of the incident light, the value derived from the storing means for storing the temporal characteristic of the reflected light, and the temporal characteristic of the incident light Comparing means for comparing both the values detected by the detecting means for detecting, and output means for outputting the comparison result, the output from the signal processing means is high directivity emitted from the light projecting means. Moreover, since the output signal is output when the scanned incident light is received, the received light beam is emitted by the light projecting means even when the optical filter and the polarization ratio processing means cannot be used for discrimination. Or regular reflection light reflected by the reflector of the light is normal, or whether the other of the external light can be accurately determined.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a light emitting and receiving device according to the present invention.

2 is a block diagram showing an internal configuration of a signal processing means 10 of FIG.

FIG. 3 is a flowchart showing an embodiment of signal processing by the signal processing means 10 of FIG.

[Explanation of symbols]

1 main body of light emitting and receiving device 12 A / D converter 2 light emitting means 13 A / D converter 3 first mirror 14 polarization ratio processing means 4 polygon mirror 15 temporal feature processing means 4'axis 16 temporal feature detecting means 5 Retroreflector 17 Memory means 6 Polarizing plate 18 Comparing means 7 Beam splitter 19 Discriminating means 8 Second mirror 20 Output means 9 Light receiving means A Polygon mirror rotation direction 10 Signal processing means 11 CPU for controlling the traveling state of a moving body

Claims (1)

[Claims] 1. A light projecting means (2), (4) for scanning while emitting highly directional light, and light incident from the light projecting means (2), (4) having the same direction of incidence. It has a reflecting means (5) for reflecting in a direction, a light receiving means (9) for receiving incident light, and a signal processing means (10), and the signal processing means (10) has a high directivity by the light projecting means. A storage means (17) for pre-storing the temporal characteristics of the reflected light obtained by scanning while emitting light and reflecting the scanned incident light in the same direction as the incident direction, the temporal characteristics of the incident light A value derived from a detection means (16) for detecting the, a storage means (17) for storing the temporal characteristic of the reflected light, and a value detected by the detection means (16) for detecting the temporal characteristic of the incident light. Comparing means (18) for comparing the two, and output means (20) for outputting the comparison result, As an output from the signal processing means (10), the light emitting and receiving device is characterized in that it outputs an output signal when it receives incident light that has a high directivity emitted from the light emitting means and is scanned. ..