Patent US4052615A successfully refreshed from Google Patents.
US4052615A
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Spherical cavity method and apparatus for measuring a sheet material property using infrared radiation
Assignee: Industrial Nucleonics Corp
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Filing: 1976-07-30
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Granted: 1977-10-04
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Expires: 1996-07-30
Abstract
Abstract A property such as moisture content in a sheet of material such as paper that both absorbs and strongly scatters infrared radiation is measured by passing the sheet through the central region of a substantially spherical cavity formed between a pair of concave mirror-surfaced, specularly reflecting bodies that are spaced apart to form a pass gap of sufficient width to allow substantially free movement of the sheet therethrough while substantially enclosing a first portion of the sheet on both sides. A spot of infrared radiation is projected onto one side of the sheet in the center of the cavity to illuminate a second portion of the sheet included within and substantially smaller than the enclosed first portion. Thus infrared radiation scattered or transmitted by the second portion is reflected from the mirror-surfaced bodies and directed back to the second portion substantially within the area of the sheet defined by the spot. The relative sizes of the first and second portions in relation to the width of the pass gap determine the relative quantities of radiation being retained in the cavity and escaping through the pass gap. On the opposite side of the sheet relative quantities of both the projected radiation transmitted by the sheet and radiation reflected from the reflective bodies are detected so as to produce an output response indicative of the measured property. The relative quantities of the retained and escaping radiation and the detected transmitted and reflected radiation are selected to make the output response substantially independent of changes in other properties affecting the scattering power of the sheet material, such as the bone-dry weight or composition of paper.
Inventors
- 👤 Boong Youn Cho
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:34
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/86
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
274 words
The method of measuring a property such as moisture content in a sheet of material such as paper that both absorbs and strongly scatters infrared radiation, comprising the steps of passing the sheet through the central region of a substantially spherical cavity formed between a pair of concave mirror-surfaced, specularly reflecting bodies that are spaced apart to form a pass gap of sufficient width to allow substantially free movement of the sheet therethrough while substantially enclosing a first portion of the sheet on both sides, projecting onto one side of the sheet in the center of the cavity a spot of infrared radiation to illuminate a second portion of the sheet included within and substantially smaller than the enclosed first portion so that infrared radiation scattered or transmitted by the second portion will be reflected from the mirror-surfaced bodies and directed back to the second portion substantially within the area of the sheet defined by the spot, the relative sizes of the first and second portions in relation to the width of the pass gap determining the relative quantities of radiation being retained in the cavity and escaping through the pass gap, and detecting on the opposite side of the sheet relative quantities of both the projected radiation transmitted by the sheet and radiation reflected from the reflective bodies so as to produce an output response indicative of said property, said relative quantities of retained and escaping radiation and detected transmitted and reflected radiation being selected to make said response substantially independent of changes in another property affecting the scattering power of the sheet material, such as the bone-dry weight or composition of paper.
Claim 2
Independent Claim
274 words
The method of measuring a property such as moisture content in a sheet of material such as paper that both absorbs and strongly scatters infrared radiation, comprising the steps of passing the sheet through the central region of a substantially spherical cavity formed between a pair of concave mirror-surfaced, specularly reflecting bodies that are spaced apart to form a pass gap of sufficient width to allow substantially free movement of the sheet therethrough while substantially enclosing a first portion of the sheet on both sides, projecting onto one side of the sheet in the center of the cavity a spot of infrared radiation to illuminate a second portion of the sheet included within and substantially smaller than the enclosed first portion so that infrared radiation scattered or transmitted by the second portion will be reflected from the mirror-surfaced bodies and directed back to the second portion substantially within the area of the sheet defined by the spot, the relative sizes of the first and second portions in relation to the width of the pass gap determining the relative quantities of radiation being retained in the cavity and escaping through the pass gap, and detecting on the opposite side of the sheet relative quantities of both the projected radiation transmitted by the sheet and radiation reflected from the reflective bodies so as to produce an output response indicative of said property, said relative quantities of retained and escaping radiation and detected transmitted and reflected radiation being selected to make said response substantially independent of changes in another property affecting the scattering power of the sheet material, such as the bone-dry weight or composition of paper.
Claim 3
Dependent Claim
18 words
A method as in claim 1 wherein the radiation is projected along a diameter of the spherical cavity.
Claim 4
Dependent Claim
43 words
A method as in claim 2 comprising detecting the radiation from a location at an angle φ from the diameter along which the radiation is projected, said angle determining the relative detected quantities of projected transmitted radiation and radiation reflected by the bodies.
Claim 5
Dependent Claim
15 words
A method as in claim 3 wherein the diameter is substantially normal to the sheet.
Claim 6
Dependent Claim
24 words
A method as in claim 3 wherein the angle φ has its apex substantially at the center of the cavity, and is about 50°.
Claim 7
Dependent Claim
26 words
A method as in claim 1 wherein the diameter of the cavity is on the order of about 5-10 times the size of the projected spot.
Claim 8
Dependent Claim
21 words
A method as in claim 1 wherein the effective reflectivity R g of the reflective bodies is about 0.5 to 0.8.
Claim 9
Independent Claim
276 words
A apparatus for measuring a property such as moisture content in a sheet of material such as paper that both absorbs and strongly scatters infrared radiation, comprising a pair of concave mirror-surfaced, specularly reflecting bodies forming a substantially spherical cavity therebetween and spaced apart to form a pass gap of sufficient width to allow substantially free movement of the sheet between the bodies and through the central region of the cavity while substantially enclosing a first portion of the sheet on both sides, means for projecting onto one side of the sheet in the center of the cavity a spot of infrared radiation to illuminate a second portion of the sheet included within and substantially smaller than the enclosed first portion so that infrared radiation scattered or transmitted by the second portion will be reflected from the mirror-surfaced bodies and directed back to the second portion substantially within the area of the sheet defined by the spot, the relative sizes of the first and second portions in relation to the width of the pass gap determining the relative quantities of radiation being retained in the cavity and escaping through the pass gap, and means for detecting on the opposite side of the sheet relative quantities of both the projected radiation transmitted by the sheet and radiation reflected from the reflective bodies so as to produce an output response indicative of said property, said relative quantities of retained and escaping radiation and detected transmitted and reflected radiation being selected to make said response substantially independent of changes in another property affecting the scattering power of the sheet material, such as the bone-dry weight of composition of paper.
Claim 10
Independent Claim
276 words
A apparatus for measuring a property such as moisture content in a sheet of material such as paper that both absorbs and strongly scatters infrared radiation, comprising a pair of concave mirror-surfaced, specularly reflecting bodies forming a substantially spherical cavity therebetween and spaced apart to form a pass gap of sufficient width to allow substantially free movement of the sheet between the bodies and through the central region of the cavity while substantially enclosing a first portion of the sheet on both sides, means for projecting onto one side of the sheet in the center of the cavity a spot of infrared radiation to illuminate a second portion of the sheet included within and substantially smaller than the enclosed first portion so that infrared radiation scattered or transmitted by the second portion will be reflected from the mirror-surfaced bodies and directed back to the second portion substantially within the area of the sheet defined by the spot, the relative sizes of the first and second portions in relation to the width of the pass gap determining the relative quantities of radiation being retained in the cavity and escaping through the pass gap, and means for detecting on the opposite side of the sheet relative quantities of both the projected radiation transmitted by the sheet and radiation reflected from the reflective bodies so as to produce an output response indicative of said property, said relative quantities of retained and escaping radiation and detected transmitted and reflected radiation being selected to make said response substantially independent of changes in another property affecting the scattering power of the sheet material, such as the bone-dry weight of composition of paper.
Claim 11
Dependent Claim
19 words
Apparatus as in claim 8 wherein the projecting means projects the radiation along a diameter of the spherical cavity.
Claim 12
Dependent Claim
45 words
Apparatus as in claim 9 wherein the detecting means comprises a radiation detector element mounted at an angle φ from the diameter along which the radiation is projected, said angle determining the relative detected quantities of projected transmitted radiation and radiation reflected by the bodies.
Claim 13
Dependent Claim
22 words
Apparatus as in claim 10 wherein the projecting means projects radiation along a diameter of the cavity substantially normal to the sheet.
Claim 14
Dependent Claim
23 words
Apparatus as in claim 10 wherein the angle φ has its apex substantially at the center of the cavity and is about 50°.
Claim 15
Dependent Claim
25 words
Apparatus as in claim 8 wherein the diameter of the cavity is on the order of about 5-10 times the size of the projected spot.
Claim 16
Dependent Claim
18 words
Apparatus as in claim 8 wherein the effective reflectivity of the reflective bodies is about 0.5 to 0.8.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-03 | 1981-04-04 | 1981-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-03 | 1985-04-04 | 1985-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-03 | 1989-04-04 | 1989-10-04 | $7700.00 | Window Closed / Lapsed |