Electro-optical windshield moisture sensing
First Claim
1. A sensing assembly (10) using radiant energy for indicating when moisture or other particles have accumulated on a window (12) having inside and outside surfaces (16) thickness (T) and of a material having an index of refraction (n) associated with the wavelength of the radiant energy, said assembly (10) comprising:
- emitter means (18) for disposition on the inside of the window (12) with gas therebetween to emit radiant energy to the window (12) on an ingress axis (A) at an incident angle (θ
) relative to the inside surface (14), detector means (20) for disposition on the inside of the window (12) with gas therebetween to detect radiant energy from the window (12) on an engress axis (B) at a reflecton angle (θ
'"'"') relative to the inside surface (14) and equal to said incident angle (θ
), support means (22) for spacing said emitter means (18) and said detector means (20) such that the point (I) of intersection of the ingress axis (A) with the inner surface of the window (12) from the point (E) of intersection of the engress axis (B) with the inside surface (14) of the window (12) is a predetermined distance (D), said predetermined distance (D) determined by the formula;
space="preserve" listing-type="equation">D=2 T cos θ
(n.sup.2 -cos.sup.2 θ
).sup.-1/2
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Abstract
The invention is a moisture sensor which includes an emitter (18) to emit pulses of radiant energy toward the inside surface (14) of a window (12) at an incident angle (θ). The radiant energy is refracted into the window (12) at the air-inside window surface (14) and reflected off the air-outside window surface (16) back through the window (12). The radiant energy is then detected by a detector (20) at a reflection angle (θ'"'"') equal to the incident angle (θ). A support (22) spaces the emitter (18) and detector (20) a distance D between the intersection (I) of the axis (A) of the emitter (18) with the inside window surface (14) and the intersection (E) of the axis (B) of the detector (20) with the inside window surface (14) which is determined by the formula:
D=2T cos θ(n.sup.2 - cos.sup.2 θ).sup.-1/2
The detector (20) includes a collimator (36) to prevent non-parallel radiant energy from entering the detector (20) and an optical filter (40) to filter out radiant energy wavelengths below a predetermined wavelength in order to detect the emitted radiant energy.
108 Citations
28 Claims
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1. A sensing assembly (10) using radiant energy for indicating when moisture or other particles have accumulated on a window (12) having inside and outside surfaces (16) thickness (T) and of a material having an index of refraction (n) associated with the wavelength of the radiant energy, said assembly (10) comprising:
- emitter means (18) for disposition on the inside of the window (12) with gas therebetween to emit radiant energy to the window (12) on an ingress axis (A) at an incident angle (θ
) relative to the inside surface (14), detector means (20) for disposition on the inside of the window (12) with gas therebetween to detect radiant energy from the window (12) on an engress axis (B) at a reflecton angle (θ
'"'"') relative to the inside surface (14) and equal to said incident angle (θ
), support means (22) for spacing said emitter means (18) and said detector means (20) such that the point (I) of intersection of the ingress axis (A) with the inner surface of the window (12) from the point (E) of intersection of the engress axis (B) with the inside surface (14) of the window (12) is a predetermined distance (D), said predetermined distance (D) determined by the formula;
space="preserve" listing-type="equation">D=2 T cos θ
(n.sup.2 -cos.sup.2 θ
).sup.-1/2 - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- emitter means (18) for disposition on the inside of the window (12) with gas therebetween to emit radiant energy to the window (12) on an ingress axis (A) at an incident angle (θ
-
17. A method of sensing moisture or other particles using radiant energy on a window (12) having inside (14) and outside (16) surfaces defining a thickness (T) and a of material having an index of refraction (n) associated with the wavelength of the radiant energy, said method comprising the steps of;
- emitting (18) radiant energy through gas to the window (12) on an ingress axis (A) at an incident angle (θ
) relative to the inside surface (14) of the window (12), detecting (20) the radiant energy from the window (2) through gas on an egress axis (B) at a reflection angle (θ
'"'"') relative to the inside surface (14) and equal to the incident angle (θ
), and spacing the point (I) of intersection of the ingress axis (A) with the inner surface (14) of the window (12) from the point (E) of intersection of the egress axis (B) with the inner surface (14) of the window (12) a distance (D) which equals;
space="preserve" listing-type="equation">D=2 T cos θ
(n.sup.2 -cos.sup.2 θ
).sup.-1/2 - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
- emitting (18) radiant energy through gas to the window (12) on an ingress axis (A) at an incident angle (θ
-
25. A sensing assembly (10) for indicating when moisture or other particles have accumulated on a window (12) having inside (14) and outside (16) surfaces and including an emitter (18) for emitting radiant energy toward the window (12), said assembly (10) comprising:
- detector means (20) for detecting radiant energy from the window (12) on an egress axis (B) to indicate when moisture or particles have accumulated on the window (12), said detector means (20) including collimator means (36) for limiting the field of view of radiant energy from the window (12) entering said detector means (20) by allowing to pass only radiant energy substantially parallel with the egress axis (B) within said field of view.
- View Dependent Claims (26, 27)
-
28. A sensing assembly (10) for indicating when moisture or other particles have accumulated on a window (12) having inside (14) and outside (16) surfaces and including an emitter (18) for emitting radiant energy toward the window (12), said assembly (10) comprising:
- detector means (20) for detecting radiant energy from the window (12) on an egress axis (B) to indicate when moisture or particles have accumulated on the window (12), said detector means (20) including limiting means (36) for limiting the field of view of radiant energy from the window (12) entering said detector means (20) by allowing to pass only radiant energy substantially parallel with the egress axis (B) within said field of view, said detector means (36) including light sensitive means (50) supported within said limiting means (36) for sensing the radiant energy.
Specification