Patent Application
20170115215
The present relates to material sensors, and more particularly to a sensor for detecting remotely located reflective materials.
Precipitation sensors have been developed to determine the presence of water in its vapor, liquid and solid forms, but usually the sensor is immersed in the material. Non-immersed sensing is a significant challenge. One example of a non-immersed sensor is the Bosch vehicle windshield rain sensor (Optical Sensor U.S. Pat. No. 6,376,824 by Michenfelder et al) used to operate windshield wipers. This sensor depends on the change in refraction of a reflected light beam against glass when water is on the outer glass surface. However, it has poor sensitivity for snow, unless the glass can be heated enough to melt the snow next to the glass. Moreover, it is unable to detect snow above the glass surface. The ability to remotely detect reflective material at a distance away can be very valuable for numerous applications that encounter reflective material (such as winter precipitation or ice formed from super cooled water droplets) wherein there may be adverse effects encountered unless otherwise detected. Examples of which include detection of mid-air ice or super cooled water in the aerospace industry which would certainly welcome such an invention since ice detection has been a challenge for many years. An example of a sensor determining the presence of a material above a surface using reflection techniques is U.S. Pat. No. 8,741,513 B2 Rain Sensor by Han. Disadvantageously, Han's sensor requires that the material be on the surface far side and be translucent so that the radiation can reflect off the material back surface through the translucent material in order to be sensed. Thus it will not detect clear ice which has a poor backside reflection. It is also susceptible to false signals such as sunlight, oncoming headlights, or street lamps shining through and mimicking a reflective signal. Han teaches that light sources and light receivers mounted on a plane inclined at an angle to the window prevent sources light from being reflected off the window surface back to light receivers. But drawing a complete set of light vectors on Han's art yields paths where source light is obviously reflected off the window surface to the light receivers, significantly reducing sensitivity to raindrop reflection signals. This loss of sensitivity is especially problematic, given that the majority of source light will pass through the raindrop rather than be reflected, and external light can also pass easily through the raindrop causing false signals to the light receivers. Han teaches the use of infrared light sources and receivers. Han's sensor specifically detects reflection from the far side of raindrops on a window surface. Han teaches a lattice pattern of light sources and receivers, suitable for the short distances in a windshield wiper control.
Another example U.S. Pat. No. 8,873,062 by Adler & Baird is described as a sensor for sensing reflective material specifically on the transparent window surface of the sensor. The surface sensor is not able to detect reflective material remotely or at a distance. While the sensor does work well in terms of detection on the transparent surface, it does not have the capabilities to effectively detect away from the surface as provided for by the application herein that provides for the use of a radiation detector focusing lens and varied radiation emitters of differing intensities and/or radiation frequencies allowing for operational flexibility in numerous light conditions, to detect reflective materials at a distance away.
Another example is U.S. Pat. No. 7,285,771 B2 Optical Sensor by Walker. Walker teaches the use of a single emitter and several detectors to determine paper position in a printer. While this sensor works well in the enclosed environment of a printer, with one emitter it does not have the flexibility to accommodate various light conditions found in other applications. Walker teaches using an infrared emitter and an enclosed housing to minimize the effect of stray light. This restricts the use to reflective material located within enclosed housing environments. Walker teaches an open air path for the radiated and reflected light. This is suitable for the benign environment in an enclosed housing in a printer.
Thus there is a need for a sensor useful in detecting remotely located reflective material
We have discovered through design, trial and error a remote reflective materials sensor that uses a reflective rather than refractive technique, and as such is very well suited to determining the presence of reflective materials located at a distance remote from a surface. A radiation source such as a Light Emitting Diode (LED) is oriented to radiate at a distance through a transparent material such as glass. In one example, the transparent material is a window. When a reflective material such as snow or rime ice is within the sensor's field of view, a radiation detector such as but not limited to a phototransistor, photo diode or light dependent resister adjacent to the radiation source, detects the radiation reflection.
Our discovery uses two radiation emitters angled to a common focal point, this focal point also being common with the radiation detector. The radiation emitters may be of differing intensities or radiation frequencies, allowing for operational flexibility in a variety of ambient light conditions and detecting a variety of reflective materials. A single radiation emitter may also be used in applications not requiring the radiation intensity or radiation frequency features of two emitters. Our discovery uses a mount, which also functions as a light baffle to prevent sensitivity degrading false reflections. Our device uses a variety of emitter and detector types, which can be modified depending on to the reflective material to be detected. Furthermore, our device uses detector path focusing lenses in the detector array embodiment that can extend the sensor range without increasing radiation emitter power. Moreover, our device provides for a temperature sensor adjacent to the transparent window to distinguish between liquid and frozen reflective materials expected in a given application. While direct sensing of the transparent window temperature provides the best accuracy, alternate methods may be used. An example is a temperature sensor located elsewhere in the housing. Another example that may be used in a turbine engine application combines remote air temperature sensing from an aircraft fuselage mounted probe with algorithmic processing of engine parameters such as RPM to deduce engine temperature at the transparent window location. For example, engine air compression ratio at any compressor stage as a function of airspeed and engine RPM is determined in prototype development, or the engine may be instrumented with a pressure sensor. A thermodynamic equation can then be used to relate measured ambient air temperature to compressor stage temperature using compression ratio. Another example which may be used is an algorithmic only approach, whereby a combination of application operating parameters such as altitude and RPM can be used to deduce temperature at the transparent window position. Other methods may also be used, based on a person of ordinary skill in the art applying methods available in any given application.
We are unaware of any devices that currently detect reflective materials at a distance from the window. Our device uses one or more emitters aligned to a common target area outside the housing to produce a usable signal under varying ambient light conditions and reflective material locations outside the housing and away from it. We describe radiating through and receiving reflected light through a housing transparent window. This is suitable for a harsh environment such as detecting reflective material on a turbine engine compressor guide vane.
Furthermore, radiating through a transparent window allows the device to be used where the window isolates the sensor from harsh environments such as high or low temperatures or pressures, corrosive, toxic or flammable materials, and the like. The transparent window is also easier to clean than emitters and detectors. The transparent window material may also be selected to be transparent to the emitter and/or detector radiation wavelengths, but filter out undesirable ambient radiation.
Accordingly, there is provided a remote reflective materials sensor for detecting remotely located reflective material, the remote reflective materials sensor comprising:
In one example, the remote reflective materials sensor further includes a housing which houses a sensor mount, the radiation detector and the radiation emitters being mounted in the sensor mount. The sensor mount includes two spaced apart cavities aligned along the respective first axes in which the radiation emitters are located, and another cavity aligned along the second axis in which the radiation detector is located.
In one example, the operating parameters sensor is selected from the group consisting of: a temperature sensor, a pressure sensor, an airspeed sensor, an RPM sensor, and an altitude sensor.
In one example, the radiation emitter is a Light Emitting Diode (LED).
In one example, the radiation emitter is an electroluminescent surface.
In one example, the radiation emitter is a narrow beam high radiation emitter. The remote reflective materials sensor, according to claim 7, in which the narrow beam high radiation emitter is a laser, or a focused emitter, the focused emitter including a focused LED, a focused incandescent bulb, or a focused electric arc.
In one example, the radiation detector is a photo transistor, a photo diode or a light dependent resister located adjacent to the radiation emitter to detect reflected radiation.
In one example, the radiation detector is an array of detectors to detect spatially separated reflective material elements including individual snowflakes, ice crystals, or successive positions of one reflective object in the sensor field of view.
In one example, the first and second radiation emitters and the housing are configured so that radiation is emitted through the transparent window without causing false radiation reflection back to the radiation detector.
In one example, a controller is located in the housing and is connected to a variable resistor, the radiation detector, the radiation emitter and the operating parameters sensor.
In one example, a controller is located in the housing and is connected to a fixed resistor, the radiation detector, the radiation emitter and the operating parameters sensor.
In one example, the radiation detector is an integrated circuit having a phototransistor, a photo diode or a light dependent resister located adjacent to the radiation emitter so as to detect reflected radiation.
In one example, the reflective material is winter precipitation. The winter precipitation is snow, sleet, frost, ice or ice pellets.
In one example, the reflective material is non-winter precipitation. The non-winter precipitation is reflective liquids, dirt, particulate material suspended in liquids, super cooled water droplets, or ice, including clear and rime ice.
According to another aspect, there is provided a use of the remote reflective materials sensor to detect reflective material located remote from the transparent window and associated with: airplanes, helicopters, drones, unmanned air vehicles, spacecraft, blimps, hybrid air/ground/marine/space vehicles, trucks, cars, motor bikes, recreational vehicles, trains, boats; sidewalks, driveways, walkways, roads, roofs, greenhouses, atriums, windows, skylights; food services, food preparation and preservation, freezer glass doors, freezers and/or refrigerators, buildings or infrastructure projects, medical applications including storage of tissues and cells, or sterilizations; landscaping including grass and garden maintenance, or crops weather determination, agriculture, climate, and ecosystem preservation; or energy production applications including solar applications for building materials including decking, walls or shingles.
In one example, the transparent window is made from a material that is transparent to emitter and detector radiation, and filters ambient radiation.
Accordingly in another aspect, there is provided a remote reflective materials sensor for detecting remotely located reflective material, the remote reflective materials sensor comprising:
Accordingly in another aspect, there is provided a remote reflective materials sensor for detecting remotely located reflective material, the remote reflective materials sensor comprising:
In one example, the operating parameters sensor is selected from the list of a temperature sensor, a pressure sensor, an airspeed sensor, an RPM sensor, and an altitude sensor.
Accordingly in another aspect, there is provided a remote reflective materials sensor for detecting remotely located reflective material, the remote reflective materials sensor comprising:
In one example, the remote reflective materials sensor, includes two spaced apart radiation emitters located on either side of the radiation detector, and away from the second window surface, each radiation emitter being configured to emit radiation along a first axis through the transparent window towards the reflective material and towards a common focal point.
In order that the discovery may be readily understood, embodiments are illustrated by way of example in the accompanying drawings.
Further details of the device and its advantages will be apparent from the detailed description included below.
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The temperature sensor only detects temperature. It does not detect barometric pressure or other parameters. It should be noted that the remote reflective materials sensor 10 will function without a temperature sensor. Without temperature, the reflective material sensor 10 assumes that any reflection is the reflective material ice of interest, and not dirt. With the temperature sensor, any reflection measured above freezing temperature can be assumed to be a foreign substance, allowing the implementation to trigger a maintenance operation by a technician.
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One skilled in the art will recognize that the reflective material sensor range can be extended by using narrow beam high radiation emitters such as, for example, lasers, focused LEDs, focused incandescent bulbs, or focused electric arcs.
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By way of example each of the radiation emitters is a Light Emitting Diode (LED).
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The reflective material sensor 10 functions in a wide range of ambient radiations, from direct sunlight to nighttime. It can remotely sense reflective material on or at a distance away from for example, greenhouses, atriums, windows, freezer glass doors, skylights; on airplanes, drones, helicopters, spacecraft, aircraft, hybrid air/space/water/land vehicle components, and motorized transportation including trucks, cars, motor bikes, recreational vehicles, trains, boats and the like; food services, freezers/fridges, buildings, photovoltaic solar (conventional panels and non conventional solar applications), trough reflectors; for landscaping such as grass and garden maintenance, crops; or for weather determination, climate, ecosystem preservation; or for medical applications and storage of tissues and cells, sterilizations; or for food preparation and preservation, and the like. When operated in non-winter conditions, the remote reflective materials sensor 10 may also detect dirt on these types of surfaces to support cleaning operations. It can also detect ice crystal accretion in the atmosphere, which may not necessarily be associated with winter conditions. The remote reflective materials sensor 10 can also sense winter precipitation when installed in sidewalks, driveways, walkways, roads, roofs, infrastructure projects and the like. The remote reflective materials sensor 10 can be used in solar applications for building materials such as decking, walls and shingles.
While the remote reflective materials sensor 10 can be used to sense winter precipitation, it is easily applied to sensing other reflective materials such as, for example, liquids, precipitates, contamination, some gases, suspended solids, and the like, and as such can be applied to manufacturing and distribution processes for food, chemicals, fuels, and the like.
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In some applications such as low ambient light or reflective material easily detected at one radiation frequency, the dual emitter operations can be readily simplified for single emitter applications by anyone skilled in the art.
It should be noted that in the Figures, the area shown as the reflective material 12 is the sensor illumination or the detection coverage area. The reflected radiation signal will vary from a low value with no reflective material in the detection coverage area to a high value with highly reflective material covering the entire detection coverage area.
From the foregoing description, it will be apparent to one of ordinary skill in the art that variations and modifications may be made to the embodiments described herein to adapt it to various usages and conditions.
