US3756692A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photochromic protective eye shield lens
Assignee: Johns Hopkins University
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Filing: 1971-07-15
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Granted: 1973-09-04
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Expires: 1991-07-15
Abstract
Abstract A protective lens structure of variable opacity for installation in a welder''s face shield to provide decreasing radiation transmission through the structure with increasing radiation impingement on the structure. The optical density of photochromic material within the lens structure varies according to the intensity of the radiation produced by the welding instrument. The photochromic material is held between an ultraviolet (UV) transmitting frontal lens and a UV-absorbing rear lens, the frontal lens having a coating with low infrared (IR) transmittance and the rear lens having a UV-reflective coating. The frontal lens essentially blocks IR while transmitting UV and visible light to the photochromic material. The UV radiation striking the front surface of the photochromic material activates the material, causing it to become optically dense. Any UV radiation transmitted through the photochromic material is reflected back into the material by the UV-reflective coating on the rear lens, thereby activating the material over the rear surface thereof. Incident radiation in the visible spectral range is predominately absorbed by the activated photochromic material. Any UV-radiation transmitted through the reflective coating is absorbed by the rear lens to prevent transmission to the user''s eyes.
Inventors
- 👤 D Scott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:27
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/22; G02B5/23; G02C; G02C7/00; G02C7/10; G02C7/102
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
113 words
A protective lens structure of variable opacity for a welder''s helmet, the lens structure providing substantially instantaneous attenuation of radiation transmittance therethrough on exposure to intense electromagnetic radiation and being essentially transparent before and after such exposure, said lens structure comprising: photochromic means absorptive to ultraviolet radiation and producing an instantaneously effective and variable opacity to visible radiation within the lens structure; lens means for preventing transmission of infrared radiation and transmitting ultraviolet and visible radiation, said lens means being disposed in front of said photochromic means; and, ultraviolet radiation reflective means disposed in back of said photochromic means for reflecting ultraviolet radiation passing through said photochromic means back into said photochromic means.
Claim 2
Dependent Claim
113 words
A protective lens structure of variable opacity for a welder''s helmet, the lens structure providing substantially instantaneous attenuation of radiation transmittance therethrough on exposure to intense electromagnetic radiation and being essentially transparent before and after such exposure, said lens structure comprising: photochromic means absorptive to ultraviolet radiation and producing an instantaneously effective and variable opacity to visible radiation within the lens structure; lens means for preventing transmission of infrared radiation and transmitting ultraviolet and visible radiation, said lens means being disposed in front of said photochromic means; and, ultraviolet radiation reflective means disposed in back of said photochromic means for reflecting ultraviolet radiation passing through said photochromic means back into said photochromic means.
Claim 3
Dependent Claim
22 words
The lens structure of claim 1, and further including ultraviolet absorption lens means disposed in back of said ultraviolet radiation reflective means.
Claim 4
Dependent Claim
177 words
A protective lens structure of variable opacity for a welder''S helmet, the lens structure providing substantially instantaneous attenuation of radiation transmittance therethrough on exposure to intense electromagnetic radiation and being essentially transparent before and after such exposure, said lens structure comprising: a lens for blocking infrared radiation and transmitting ultraviolet and visible radiation therethrough; a lens for absorbing ultraviolet radiation; an ultraviolet reflective coating on the front surface of the second-mentioned lens; and, a layer of photochromic material located between said lenses and capable of instantaneously reacting to the impingement of ultraviolet radiation thereon during such exposure for producing variable opacity to visible radiation in the lens structure, the opacity of said photochromic material having a first minimum predetermined value prior to exposure to said intense electromagnetic radiation which instantaneously increases to a second predetermined value during such exposure, said opacity being variable in accordance with the intensity of said electromagnetic radiation and rapidly decreasing to said first minimum predetermined value upon removal of said intense electromagnetic radiation for allowing a user to observe the welding area.
Claim 5
Dependent Claim
177 words
A protective lens structure of variable opacity for a welder''S helmet, the lens structure providing substantially instantaneous attenuation of radiation transmittance therethrough on exposure to intense electromagnetic radiation and being essentially transparent before and after such exposure, said lens structure comprising: a lens for blocking infrared radiation and transmitting ultraviolet and visible radiation therethrough; a lens for absorbing ultraviolet radiation; an ultraviolet reflective coating on the front surface of the second-mentioned lens; and, a layer of photochromic material located between said lenses and capable of instantaneously reacting to the impingement of ultraviolet radiation thereon during such exposure for producing variable opacity to visible radiation in the lens structure, the opacity of said photochromic material having a first minimum predetermined value prior to exposure to said intense electromagnetic radiation which instantaneously increases to a second predetermined value during such exposure, said opacity being variable in accordance with the intensity of said electromagnetic radiation and rapidly decreasing to said first minimum predetermined value upon removal of said intense electromagnetic radiation for allowing a user to observe the welding area.
Claim 6
Dependent Claim
112 words
A process for rapidly attenuating intense electromagnetic radiation incident on a lens structure comprising a viewing port in a welder''s headgear, the process comprising; blocking the transmission of infrared radiation through the lens structure; transmitting ultraviolet and visible radiation at least into the interior of the lens structure; disposing a photochromic material within the interior of the lens structure; exposing the front surface of the photochromic material to the transmitted ultraviolet radiation thereby to darken the material and prevent transmission through the lens structure of intense visible radiation; and reflecting any ultraviolet radiation transmitted through the photochromic material back into the photochromic material over the rear surface thereof to darken the material.
Claim 7
Dependent Claim
112 words
A process for rapidly attenuating intense electromagnetic radiation incident on a lens structure comprising a viewing port in a welder''s headgear, the process comprising; blocking the transmission of infrared radiation through the lens structure; transmitting ultraviolet and visible radiation at least into the interior of the lens structure; disposing a photochromic material within the interior of the lens structure; exposing the front surface of the photochromic material to the transmitted ultraviolet radiation thereby to darken the material and prevent transmission through the lens structure of intense visible radiation; and reflecting any ultraviolet radiation transmitted through the photochromic material back into the photochromic material over the rear surface thereof to darken the material.
Claim 8
Dependent Claim
20 words
The process of claim 4, and further comprising the step of: absorbing any ultraviolet radiation transmitted through the lens structure.
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) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |