JPWO2014157511A1 - Reflected light measuring device - Google Patents

Abstract

Provided is a reflected light measurement device that has a simple structure and good workability in processing and assembly while eliminating the influence of stray light caused by reflection on the top and bottom surfaces of a window. A housing case 25 that houses an optical system including a light source 21 that emits light toward the measurement target surface and a light receiving unit 24 that receives reflected light from the measurement target surface, and has an opening in the direction of the measurement target surface; An exit window 27 inclined at a predetermined angle with respect to the optical axis Y of the light emitted from the light source 21 is provided in a part of the window 26 of the reflected light measurement device provided with a window 26 that seals the opening of the housing case 25; The light emitted from the light source 21 is irradiated toward the measurement target surface through the emission window 27.

Description

  The present invention measures the amount of light reflected from the light source to the measurement target surface to detect the presence or absence of a detection target existing on the measurement target surface, and the distance to the measurement target surface or the reflectance of the measurement target surface. The present invention relates to a reflected light measuring device for measuring the above.

  Conventionally, the amount of light reflected from the light source to the measurement target surface is measured to detect the presence or absence of a detection target existing on the measurement target surface, and the distance to the measurement target surface or the reflectance of the measurement target surface is determined. As a reflected light measuring device for measurement, for example, an oil film detecting device, a distance measuring device, a reflectance measuring device, and the like are known. These reflected light measuring devices contain a light source for irradiating light and a light receiving unit for receiving reflected light in a housing case to prevent water condensation in an optical system and protect an electrical part, and are sealed watertight by a window. It is configured.

  In such a reflected light measuring device, normal measurement may be disturbed by stray light other than the light intended for the measurement. The following apparatus is used as a reflected light measuring apparatus in which measures are taken to eliminate the influence of stray light caused by reflection / scattering of light from the light source by the top surface (inner surface) and bottom surface (outer surface) of the window. Is provided.

  For example, a detector of a conventional oil film detection apparatus such as Patent Document 1 includes a light source 11, a concave mirror 12, a light receiving unit 14 and the like as shown in FIG. It is configured to be housed in the housing case 15 and sealed in a watertight manner by the window 16. The window 16 is attached with an inclination from a vertical surface with respect to the side wall of the housing case 15 (a parallel surface with respect to the horizontal section of the housing case 15) so as to be inclined at a predetermined angle with respect to the optical axis X of the light emitted from the light source. It has been. This is to prevent the light emitted from the light source 11 from being reflected on the top and bottom surfaces of the window 16 and becoming stray light. For example, the light emitted from the light source 11 and reflected from the top surface of the window 16 Is incident on the concave mirror 12, the reflected light is guided to the point A and does not enter the light receiving unit 14.

  Patent Document 2 discloses a light projecting element that generates light and irradiates an object with a light projection beam, a position detection type light receiving element that receives reflected light from a measurement object via a light receiving lens, and a light receiving element. And a signal processing means for detecting the distance to the measurement object based on the output of the light beam, and a position perpendicular to the light projection beam at a position where the light projection beam and the scattered light from the measurement object are transmitted. Light attenuation that attenuates the reflected light by placing it at an angle from the surface and forming a window material that forms part of the case that houses the light projecting element and the light receiving element, and a position where the light projection beam is directly reflected by the window material A distance measuring device comprising means is disclosed.

International Publication No. 2009/022649 JP-A-7-301519

  However, these conventional reflected light measuring devices are mounted with the window for sealing the opening of the storage case being inclined at a predetermined angle from a vertical surface with respect to the side wall of the storage case (a parallel surface with respect to the horizontal cross section of the storage case 15). Therefore, there is a problem that the design and processing are complicated, the workability of processing and assembly is poor, and the cost is increased.

  Further, in the conventional measuring apparatus, since the window 16 is attached to the detector 10 at a predetermined angle with respect to the optical axis as in the conventional oil film detecting apparatus shown in FIG. There is a problem that the size of the direction is increased and the detector 10 is increased in size.

  Further, for example, a conventional distance measuring apparatus such as Patent Document 2 removes the influence of stray light caused by the top and bottom surfaces of the window, and similarly to the conventional oil film detector of FIG. Are attached to the apparatus at a predetermined angle with respect to the optical axis. However, in order to prevent the stray light from adversely affecting the measurement, the housing is provided with a light attenuating means for shielding and attenuating stray light. Therefore, the structure is complicated and the cost increases due to the increase in parts. There was a problem.

  The present invention has been made in order to solve the above-described problems, and is easy to work and assemble with a simple structure while eliminating the influence of stray light caused by reflection on the top and bottom surfaces of the window. An object of the present invention is to provide a reflected light measuring device.

  In order to achieve the above object, a reflected light measuring apparatus according to the present invention includes a light source that irradiates light toward a measurement target surface, and a light reception signal that receives the reflected light from the measurement target surface and that corresponds to the amount of light received. A reflected light measuring apparatus comprising: an optical system including a light receiving unit that outputs a light; a housing case that houses the optical system and has an opening in a direction of the measurement target surface; and a window that seals the opening of the housing case. The window is disposed perpendicular to the side wall of the housing case, and has a part of the window that has an exit window inclined at a predetermined angle with respect to the optical axis of the light source, and the light emitted from the light source. Is irradiated toward the surface to be measured through the exit window.

  According to the present invention, the window itself that seals the opening of the housing case is arranged perpendicular to the side wall of the housing case, and therefore, the structure for sealing the opening of the housing case may be a general one, and processing and assembly work It is possible to provide a reflected light measuring device with good characteristics. In addition, an exit window that transmits the emitted light is provided in a part of the window so as to be inclined at a predetermined angle with respect to the optical axis of the light emitted from the light source. It is possible to provide a reflected light measuring apparatus that can accurately measure the influence of the generated stray light on the measurement.

It is a schematic sectional drawing which shows typically the structural example and effect | action of a detector of the oil film detection apparatus which is an example of the reflected light measuring apparatus in embodiment of this invention. It is the bottom view which looked at the storage case in FIG. 1 from the lower surface (water surface) side, and is a figure which shows the positional relationship of a light-receiving part and an emission window. It is a schematic sectional drawing which shows typically the structural example and effect | action of a detector of the oil film detection apparatus which are examples of the conventional reflected light measuring apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
An oil film detection device, which is an example of a reflected light measurement device according to an embodiment of the present invention, irradiates a measurement target surface such as a water surface with a laser beam from a light source, receives reflected light from the measurement target surface, and applies it to the measurement target surface. The oil film which exists is detected. This focuses on the fact that the reflectance of light from the oil film is higher than the reflectance of light from the water surface, measures the intensity of the reflected light from the water surface (the amount of light received), and processes the light reception signal according to the amount of light received Thus, a method using the difference in light reflectance between the water surface and the oil film, which detects the oil film, is employed. In general, it is said that the reflectance of light from the water surface is about 2%, and the reflectance of light from the oil film is between 3 and 4%, and the reflected light from the oil film is 1.5 to 2 times greater. So strong. Therefore, the presence or absence of an oil film is detected by applying light of a certain intensity to the water surface, measuring the intensity of the reflected light (the amount of light received) by the light receiving unit, and processing the light received signal in various ways. Can do. When an oil film is detected, an alarm is output.

  FIG. 1 is a schematic cross-sectional view schematically showing a configuration example and an operation of a detector 20 of an oil film detection device which is an example of a reflected light measurement device according to an embodiment of the present invention. The oil film detection apparatus in this embodiment includes a detector 20 as shown in FIG. 1 and a converter (not shown). The detector 20 and the converter are connected by a cable, and a signal based on the intensity (the amount of received light) of the reflected light measured by the detector 20 is sent to the converter. The converter can perform various arithmetic processes to detect / determine the presence / absence of an oil film, and can output an alarm or display a state on the display unit when an oil film is detected. Further, the converter can output a control signal for controlling the detector 20.

  The detector 20 includes a housing case 25 that houses the light source / scanning unit 21, the concave mirror 22, and the light receiving unit 24, and a window 26 that seals the housing case 25 in a watertight manner, on the water surfaces 19 and 29 that are detection target surfaces, It is installed so as to be substantially parallel to the water surfaces 19 and 29 (substantially parallel to the horizontal direction). The housing of the detector 20 is formed of a material that does not transmit light, and light does not enter the housing case 25 from other than the window 26 (including the emission window 27).

  The light source / scanning unit 21 includes a laser light source and a scanning unit that scans the laser beam, and scans the laser beam around the optical axis Y, thereby forming a desired plane as the irradiation range of the laser beam on the detection target surface. It can be formed. The light source / scanning unit 21 is disposed above the concave mirror 22 and attached so that the emitted laser light is irradiated in a substantially vertical direction toward the water surfaces (detection target surfaces) 19 and 29.

  The concave mirror 22 is disposed so that the optical axis Z thereof is orthogonal to the horizontal direction, and has a through hole 23 at a position shifted from the optical axis Z (the central portion of the concave mirror 22). The light emitted from the portion 21 and passing through the through hole 23 and reflected by the water surfaces 19 and 29 can be collected by the reflecting surface and incident on the light receiving portion 24 disposed at the focal position on the optical axis Z. It is like that. The size of the through hole 23 is preferably the same as or slightly larger than the range through which the light emitted and scanned by the light source / scanning unit 21 is transmitted. In order to efficiently detect the reflected light from the water surfaces 19 and 29, the position of the through hole 23 is preferably close to the optical axis Z (the central part of the concave mirror 22), but the light passing through the through hole 23 The position needs not to be directly incident on the light receiving unit 24.

  The housing case 25 includes a light source / scanning unit 21, a concave mirror 22, and a light receiving unit 24, and a window 26 that seals the opening of the housing case 25 in a watertight manner. In addition, the inner side surface of the housing case 25 including the point B, except for the window 26 (including the exit window 27 portion), the stray light that is reflected in the housing case 25 is not further reflected, for example, It has a structure that absorbs light by making it black.

The window 26 is attached perpendicular to the side wall of the storage case 25 (parallel to the horizontal cross section of the storage case 25) so as to seal the storage case 25 in a watertight manner. In addition, the window 26 has an emission window 27 that is inclined at a predetermined angle with respect to the optical axis Y of the light emitted from the light source.
The emission window 27 is positioned in the vertical direction of the light source / scanning unit 21 and transmits light emitted from the light source. The inclination angle of the exit window 27 is such that the light emitted from the light source and reflected by the top and bottom surfaces of the exit window 27 is guided to a position (for example, point B) off the concave mirror 22; (2) Even if the light enters the concave mirror 22 and is further reflected, the light does not enter the light receiving unit 24 and does not come out of the housing case 25 through the window 26 (including the exit window 27 portion). It can be determined according to the curvature of the concave mirror 22, the size of the light receiving unit 24, the position of the exit window 27, etc. on the condition that any one of them is satisfied. The size of the emission window 27 is preferably the same as or slightly larger than the range through which the light emitted and scanned by the light source / scanning unit 21 is transmitted.
The window 26 and the emission window 27 may be any one that transmits light emitted from the light source and reflected light, and is formed of a transparent resin such as acrylic in terms of ease of processing, weight, cost, and the like. However, the material is not limited and glass or the like can be used.

FIG. 2 is a bottom view of the housing case 25 in FIG. 1 as viewed from the lower surface (water surface) side, and shows the positional relationship between the light receiving unit 24 and the emission window 27. As described above, the position of the through hole 23 is preferably close to the optical axis Z (the central part of the concave mirror 22), but it is necessary to prevent the light passing through the through hole 23 from directly entering the light receiving unit 24. Therefore, the exit window 27 is also provided at a position that does not overlap with the light receiving unit 24, so that light traveling toward the exit window 27 is not blocked by the light receiving unit 24. That is, the light source / scanning unit 21, the through-hole 23, and the emission window 27 are arranged in parallel with the optical axis Z at a position slightly deviated from the optical axis Z (the central part of the concave mirror 22).
The thin plate 24a is attached to the housing case 25 in order to fix the light receiving unit 24 at the focal position on the optical axis Z of the concave mirror 22, so that the position of the light receiving unit 24 can be finely adjusted. Although not shown in FIG.

Next, the operation and action of an oil film detection apparatus which is an example of the reflected light measurement apparatus according to this embodiment will be described with reference to FIG.
The light emitted and scanned by the light source / scanning unit 21 is irradiated in a substantially vertical direction within a range having a spread as indicated by a broken line around the optical axis Y of the light emitted from the light source. This light is transmitted through the exit window 27 provided in a part of the window 26. Since the exit window 27 is inclined at a predetermined angle with respect to the optical axis Y of the light emitted from the light source, even if the light reflected by the top and bottom surfaces is reflected into the housing case 25 and stray light is generated, the concave mirror The light is guided to the point B off 22 and does not become stray light that hinders the measurement of reflected light.

The light transmitted through the exit window 27 is reflected by the water surfaces 19 and 29, passes through the window 26, and reaches the light receiving unit 24 through the concave mirror 22. The broken line in FIG. 1 represents the optical path when the water surfaces 19 and 29 are perfectly flat at the outer edge of the light irradiation range. However, in actual measurement, the water surfaces 19 and 29 have fluctuations (waves). ), The reflected light does not always return to the concave mirror 22 along a constant optical path, and the possibility that the oil film is detected increases as the reflecting surface of the concave mirror 22 increases.
Moreover, the water surface 19 shows a state when the water level is high, and the water surface 29 shows a state when the water level is low. Since the light emitted from the light source / scanning unit 21 is irradiated in a substantially vertical direction, even if the water level fluctuates, a plane on which light is irradiated to the water surfaces 19 and 29 is always formed, and the light reflected on the surface is a concave mirror. 22 can be captured.
The light reception signal corresponding to the light intensity (light reception amount) detected by the light receiving unit 24 is sent to the converter and subjected to various calculation processes, and is used for determining the presence or absence of an oil film. When an oil film is detected, processing such as outputting an alarm signal is performed.

  As described above, in the oil film detection device which is an example of the reflected light measurement device according to the embodiment of the present invention, the window 26 for watertightly sealing the housing case 25 is perpendicular to the side wall of the housing case 25 (horizontal of the housing case 25). Since the housing case 25 is sealed in a watertight manner, a general structure may be used, and workability of processing and assembly is good.

  The emission window 27 emits laser light emitted from the light source / scanning unit 21 from the light source in order to prevent light reflected from the top and bottom surfaces of the window 26 from being detected as stray light by the light receiving unit 24. The light is provided obliquely with respect to the optical axis Y of the light, that is, inclined by a predetermined angle with respect to the optical axis Y. Here, in this embodiment shown in FIG. 1, if one window is attached obliquely as in the conventional oil film detection device shown in FIG. 3, the size in the vertical direction will be considerably large. Therefore, in the embodiment of the present invention, the window 26 is arranged perpendicular to the side wall of the housing case 25, and only the emission window 27 through which the laser beam emitted from the light source / scanning unit 21 is transmitted is emitted from the light source. It is configured to be inclined at a predetermined angle with respect to the optical axis Y of the light.

As a result, the laser light emitted from the light source / scanning unit 21 is prevented from being reflected by the window 26 and becoming stray light, and the reflected light can be measured with high accuracy.
In addition, since the space efficiency is good without increasing the height dimension, an increase in the size of the apparatus can be avoided.

  The present embodiment has been described with an oil film detection device that is an example of a reflected light measurement device, but is a reflected light measurement device that measures the amount of reflected light emitted from a light source to a measurement target surface, for example, a distance measurement device, The present invention can also be implemented in a reflectance measuring device or the like. In the case of these measurement devices, unlike the oil film detection device, the direction of light irradiating the measurement target surface is not limited to the substantially vertical direction. For example, the light can be irradiated substantially parallel to the horizontal direction. . In this case, the window 26 is arranged parallel to the vertical cross section of the housing case 25. Further, since the exit window 27 is inclined at a predetermined angle with respect to the optical axis Y of the light emitted from the light source, it is possible to eliminate the influence of stray light that hinders the measurement. Since the number of components can be reduced as compared with the case where the light attenuating means is provided as in the conventional distance measuring device, it is inexpensive and has a simple structure.

  Further, in the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted within the scope of the invention.

DESCRIPTION OF SYMBOLS 10,20 Detector 11,21 Light source and scanning part 12,22 Concave mirror 14,24 Light receiving part 15,25 Storage case 16,26 Window 19,29 Water surface (detection object surface)
23 Through-hole 27 Emission window X, Y Optical axis of light emitted from light source Z Optical axis of concave mirror

Claims (1)

An optical system including a light source that emits light toward a measurement target surface, and a light receiving unit that receives reflected light from the measurement target surface and outputs a light reception signal according to the amount of light received;
A housing case for housing the optical system and having an opening in the direction of the measurement target surface;
A window for sealing the opening of the housing case;
A reflected light measuring device comprising:
The window is disposed perpendicular to the side wall of the housing case, and has a part of the window that is inclined at a predetermined angle with respect to the optical axis of the light emitted from the light source,
The reflected light measuring apparatus, wherein the light emitted from the light source is irradiated toward the measurement target surface through the emission window.

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