Variable light-filtering device

• US 3,873,185 A
• Filed: 06/27/1973
• Issued: 03/25/1975
• Est. Priority Date: 06/21/1971
• Status: Expired due to Term

• Current Assignee: Howard G. Rogers
• Original Assignee: Howard G. Rogers
• Inventors: Rogers, Howard G.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Tokar, Michael J.
• Application Number:
  US05/374,252
• Time in Patent Office: 636 Days
• Field of Search: 252/300 350/147,150,151,160,158,156,160 96/88
• US Class Current: 359/275
• CPC Class Codes: C09K 9/02 Organic tenebrescent materials
• CPC Class Codes: F21S 41/135 Polarised
• CPC Class Codes: G02F 1/1503 caused by oxidation-reduction reactions in organic liquid solutions, e.g. viologen solutions
• CPC Class Codes: G03C 1/705 Compositions containing chalcogenides, metals or alloys thereof, as photosensitive substances, e.g. photodope systems used as photoresist G03F7/004
• CPC Class Codes: G03G 17/02 with electrolytic development

Abstract

This invention relates to light filters employing redox compounds that are substantially light-transmitting in their oxidized state and capable of forming a stable colored free radical upon the addition of electrons. The colored free radical formed in response to the flow of electric current renders the device light-absorbing. To restore the original lighttransmitting properties, the colored free radical may be readily reoxidized, for example, by reversing the direction of current flow.

Claims

1. In a vehicle having at least one headlamp and a windshield, the improvement which comprises positioning in coextensive relationship with said windshield a variable light-filtering device comprising a pair of spaced, parallel, coextensive lighttransmitting electrodes, a layer of a light-transmitting redox compound capable of forming a stable colored free radical upon the addition of electrons confined between said electrodes and means for flowing an electric current in a predetermined direction through said device.

2. A vehicle as defined in claim 1 wherein said redox compound is a 4,4'"'"''"'"'-dipyridylium compound, a diazapyrenium compound or a pyrazidinium compound.

3. In a vehicle having at least one headlamp including a light bulb and a protective transparent cover and a windshield, the improvement which comprises positioning in coextensive relationship with said transparent cover a variable light-filtering device comprising a pair of spaced, parallel, coextensive light-transmitting electrodes, a layer of a light-transmitting redox compound capable of forming a stable colored free radical upon the addition of electrons confined between said electrodes and means for flowing an electric current in a predetermined direction through said device.

4. A vehicle as defined in claim 3 which additionally includes a light-filtering device positioned in coextensive relationship with said windshield, said light-filtering device comprising a pair of spaced, parallel, coextensive light-transmitting electrodes, a layer of a light-transmitting redox compound capable of forming a stable colored free radical upon the addition of electrons confined between said electrodes, and means for flowing an electric current in a predetermined direction through said device.

5. A vehicle as defined in claim 4 wherein said redox compound is a 4,4'"'"''"'"'-dipyridylium compound, a diazapyrenium compound or a pyrazidinium compound.

6. A vehicle as defined in claim 1 wherein said redox compound is a polymer.

7. A device according to claim 1 including means for reversing the direction of current flow.

8. A device according to claim 7 including means for automatically predetermining said direction of current flow.

9. A vehicle as defined in claim 6 wherein said headlamp contains light-polarizing means and said redox compound is a molecularly oriented redox polymer.

10. A vehicle as defined in claim 9 wherein said headlamp light-polarizing means comprises a variable light-filtering device comprising a pair of spaced, parallel, coextensive light-transmitting electrodes, a layer of a light-transmitting molecularly oriented redox polymer capable of forming a stable colored free radical upon the addition of electrons confined between said electrodes, and means for flowing an electric current in a predetermined direction through said device.

11. A vehicle as defined in claim 9 wherein said variable light-filtering device in coextensive relationship with said windshield includes a light-polarizing sheet substantially coextensive with and having one surface in juxtaposition with the outer surface of one of said electrodes.

12. A vehicle as defined in claim 9 wherein said polymer is a 4, 4'"'"''"'"'-dipyridylium polymer.

13. A vehicle as defined in claim 12 wherein said polymer is poly-N,n-butylene-4,4'"'"''"'"' -dipyridylium dibromide.

14. A vehicle as defined in claim 1 wherein said redox compound is capable of functioning as its own electrolyte.