JPH0587735A - Visual range measuring instrument - Google Patents

Abstract

PURPOSE:To improve the measurement accuracy of a visual range measuring instrument which does not require any adjustment on its optical axis and can be easily set by preventing the influence of the contamination of the air and a lens system and deterioration of a light source, as well as optical axis misalignment due to an external force. CONSTITUTION:A light emitting section 7, first light receiving section 8 for transmitted light, and second light receiving section 9 for scattered light are integrally supported in an enclosure 1. When it becomes snowy or foggy 21 at the time of measuring a visual range, the light 20 emitted from the section 7 collides with the snow or fog 21 and transmitted light 22 decreases and the amount of scattered light 23 increases. An arithmetic processing circuit 18 finds the visual range corresponding to the concentration of the snow or fog 21 by performing arithmetic processing on the quantities of transmitted light 22 and scattered light 23. Because of the arithmetic processing, the influence of the contamination of a lens system and deterioration of the light source 10 of the light emitting section 7 can be prevented to some extent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visibility measuring device for measuring a field of view for safety of driving a car or operating an aircraft.

[0002]

2. Description of the Related Art FIG. 4 shows the structure of a conventional visibility measuring device.

In FIG. 4, 31 is a light emitting device and 32 is a light receiving device. These light emitting device 31 and light receiving device 32 have the same optical axis and are installed on the ground 33 at a distance of 50 to 100 m.

The operation of the above configuration will be described below. The light emitter 31 always emits light, and the light receiver 3
2 always receives light. Here, it is assumed that the light receiving level during fine weather (the visibility at this time is infinite) is the maximum, and the worst state in which the field of view is blocked by rain, snow, fog, or the like is 0. An example of these correlations is shown in FIG. Therefore, the transmitted light level 3 received by the light receiver 32 is
From 4, it is possible to numerically measure the visibility condition, that is, the visibility distance.

[0005]

However, in the above-mentioned conventional visibility measuring device, the light emitting device 31 and the light receiving device 32 are arranged in the range of 50.
Since they are installed at a distance of ~ 100m, the optical axes of each other will be misaligned due to an earthquake or storm during long-term use.
Along with this, an error is caused in the correlation between the light receiving level and the visibility distance shown in FIG. Further, the transmitted light level 34 is affected by dirt in the atmosphere, dirt on the lens system, and deterioration of the light source, so that the measurement accuracy is deteriorated. Moreover, the optical axis must be adjusted at the time of installation, and there is a problem that this adjustment work is troublesome.

The present invention solves the above-mentioned conventional problems, and the installation work can be easily performed without adjusting the optical axis, and the influence on the optical axis due to an earthquake or a windstorm can be prevented. As well as dirt in the atmosphere, dirt on the lens system,
An object of the present invention is to provide a visibility measuring device capable of preventing the influence of deterioration of a light source and improving measurement accuracy.

[0007]

In order to achieve the above-mentioned object, the present invention is arranged such that one light emitting portion and an optical axis of the light emitting portion coincide with each other, and the transmitted light from the light emitting portion is received. And a second light receiving unit that is arranged such that the optical axes of the light emitting unit and the first light receiving unit are different, and that receives a part of the scattered light of the light emitted from the light emitting unit. The light emitting section and the supporting means for integrally supporting the first and second light receiving sections are provided.

[0008]

Therefore, according to the present invention, since the light emitting portion and the light receiving portion are integrally supported by the supporting means, it is not necessary to adjust the optical axis at the time of installation, and even if an external force is applied. Even if added, it is possible to prevent relative deviation between the optical axes of the light emitting portion and the light receiving portion. Further, by using the second light receiving portion for scattered light in addition to the first light receiving portion for transmitted light and performing arithmetic processing on the transmitted light level and the scattered light level,
It is possible to obtain the correlation between the visibility distance and the relative value of received light, and to prevent the effects of dirt in the atmosphere, dirt on the lens system, and deterioration of the light source.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 (a) and 1 (b) show a visibility measuring device according to an embodiment of the present invention. FIG. 1 (a) is a plan view and FIG. 1 (b) is a perspective view.

As shown in FIGS. 1A and 1B, the housing 1
Is formed in a frame shape by connecting the base end portions of the pair of support portions 2 and 3 by the connecting portion 4, and the width between the support portions 2 and 3 is gradually widened from the base side to the tip side, and between the tip portions. Is set to a desired distance for visibility measurement. The housing 1 is supported on the ground 6 by a plurality of columns 5. A light emitting unit 7 and a first light receiving unit 8 for transmitting light, which face each other and have a common optical axis, are attached between the front ends of the supporting units 2 and 3 of the housing 1, and the supporting unit 3 has a first light receiving unit 8. Inside the light receiving unit 8, a second light receiving unit 9 for scattered light having an optical axis different from that of the first light emitting unit 8 and the first light receiving unit 9 is attached. The second light receiving portions 8 and 9 are integrally supported by the housing 1. A light source 10 including a light emitting diode or a laser diode and a drive circuit 11 for the light source 10 are incorporated in the light emitting unit 7. A condenser lens 12, a light receiving element 13, and a detection circuit 14 are incorporated in the first light receiving section 8. Similarly, a condenser lens 15, a light receiving element 16 and a detection circuit 17 are also incorporated in the second light receiving section 9. An arithmetic processing circuit 18 is provided in the supporting portion 2 of the housing 1, and the arithmetic processing circuit 18 includes the first and second light receiving portions 8 and 9.
The signals of the detection circuits 14 and 17 are compared and calculated, and power is supplied to the drive circuit 11 of the light emitting unit 7.

The operation of the above configuration will be described below. The light emitting unit 7 emits a light beam 20 modulated at about 2 KHz from the light source 10 toward the first light receiving unit 8 by driving the driving circuit 11. By thus modulating the light emitted from the light source 10 to about 2 KHz, it is possible to avoid the influence of sunlight and illumination light. If there is no dirt in the atmosphere, the light beam 20 is hardly attenuated and is condensed on the light receiving element 13 by the condenser lens 12 of the first light receiving unit 8. Therefore, in this case, almost no light enters the second light receiving unit 9. When snow or fog 21 occurs in the atmosphere, the light ray 20 is greatly attenuated and becomes a light ray 22 and is incident on the first light receiving unit 8. On the other hand, a part of the light scattered by the snow or fog 21 becomes a light ray 23 and is incident on the second light receiving portion 9, and is condensed on the light receiving element 16 by the condenser lens 15.

FIG. 2 shows the outputs when the detection circuits 14 and 17 detect the attenuation of the transmitted light 22 and the increase of the scattered light 23 due to snow or fog 21 in the state where there is no dirt in the atmosphere.
Is shown in the correlation diagram of. Reference numeral 24 represents the transition of the transmitted light 22, and 25 represents the transition of the scattered light 23. Figure 3 shows the scattered light level 25
And the received light relative level 26 which is an example of the result when the transmitted light level 24 is divided by the arithmetic processing circuit 18.

When snow or fog 21 is generated in the atmosphere, the transmitted light 22 is attenuated as shown by the transmitted light level 24, and the scattered light 23 is increased to a certain level as shown by the scattered light level 25. By performing arithmetic processing on these two in the arithmetic processing circuit 18, a substantially linear correlation is obtained between the visibility distance and the light receiving relative value as shown by the light receiving relative level 26 in FIG. An accurate visibility distance corresponding to the density is measured. Further, as described above, the transmitted light 22 and the scattered light 23
By measuring the two of the above, when measuring the visibility distance,
It is possible to cancel the influence of the contamination of the condenser lens systems 12 and 15 and the deterioration of the light source 10.

In measuring the visibility distance as described above, since the light emitting portion 7 and the first and second light receiving portions 8 and 9 are integrally supported by the housing 1, the optical axis is adjusted on site. It is possible to prevent the influence on the optical axis due to an earthquake or a windstorm, etc.

[0016]

As described above, according to the present invention, since the light emitting portion and the light receiving portion are integrally supported by the supporting means, it is not necessary to adjust the optical axis at the time of installation, and the installation work is facilitated. Become. Further, it is possible to prevent the optical axis from being affected by an earthquake or a windstorm. Moreover, since two light receiving parts are provided to detect transmitted light and scattered light, dirt in the atmosphere and dirt in the lens system are detected. The influence of deterioration of the light source can be prevented, and therefore the measurement accuracy can be improved.

[Brief description of drawings]

FIG. 1A is a plan view of a visibility measuring apparatus according to an embodiment of the present invention, and FIG. 1B is a perspective view of the visibility measuring apparatus.

FIG. 2 (a) is a correlation diagram of the levels of transmitted light and scattered light obtained by the visibility measuring device and the visibility distance.

FIG. 3 is a correlation diagram of a visibility distance and a light reception relative value obtained by the visibility measuring device.

FIG. 4 is a side view of a conventional visibility measuring device.

FIG. 5 is a correlation diagram of visibility distance and light reception level obtained by the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 7 Light emitting part 8 First light receiving part 9 Second light receiving part 18 Arithmetic processing circuit

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[Procedure amendment]

[Submission date] September 21, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

FIG. 2 is a correlation diagram of the levels of transmitted light and scattered light obtained by the visibility measuring device and the visibility distance.

Claims (1)

[Claims] 1. A light emitting section, a first light receiving section which is arranged so that its optical axis coincides with that of the light emitting section, and which receives transmitted light from the light emitting section, and the light emitting section and the first light receiving section. And a second light receiving portion that is arranged so that the optical axis is different from that of the light receiving portion and that receives a part of the scattered light of the light emitted from the light emitting portion, and the light emitting portion and the first and second light receiving portions are integrally formed. A visibility measuring device having a supporting means for supporting.