VARIABLE LIGHT-FILTERING DEVICE WITH A REDOX COMPOUND WHICH FUNCTIONS AS ITS OWN ELECTROLYTE

• US 3,652,149 A
• Filed: 09/02/1969
• Issued: 03/28/1972
• Est. Priority Date: 09/02/1969
• 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): McGraw, V. P.
• Application Number:
  US04/854,522
• Time in Patent Office: 938 Days
• Field of Search: 350/160,161
• US Class Current: 359/275
• CPC Class Codes: C09K 9/02 Organic tenebrescent materials
• CPC Class Codes: F21S 41/135 Polarised
• CPC Class Codes: G02B 5/24 Liquid filters G02B5/23 takes precedence
• CPC Class Codes: G02F 1/1503 caused by oxidation-reduction reactions in organic liquid solutions, e.g. viologen solutions
• CPC Class Codes: G02F 1/153 Constructional details
• 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

2. A variable light-filtering device comprising a pair of spaced, parallel, coextensive light-transmitting electrodes, a layer of a light-transmitting redox compound (a) capable of functioning as its own electrolyte and (b) 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, said redox compound being the sole electrolyte.

3. A device according to claim 2 wherein said layer contains an oxidizing agent.

4. A device according to claim 2 including means for reversing the direction of current flow.

5. A device according to claim 4 including means for automatically predetermining said direction of current flow.

6. A device according to claim 2 wherein said layer comprises a solution of said redox compound in a light-transmitting solvent.

7. A device accordiNg to claim 6 wherein said solvent is water.

8. A device according to claim 6 wherein said solvent is an electrically stable organic liquid.

9. A device according to claim 2 wherein said layer comprises said redox compound in a light-transmitting solid matrix.

10. A device according to claim 9 wherein said matrix is a gel.

11. A device according to claim 9 wherein said matrix is a polymer.

12. A device according to claim 2 wherein said redox compound is a polymer.

13. A device according to claim 2 including a third electrode in contact with said layer of compound and positioned outside the field of light-transmittancy of said pair of light-transmitting electrodes, and means for maintaining said pair of light-transmitting electrodes at the same potential and said third electrode at a different potential.

14. A device according to claim 2 wherein said compound is a diazapyrenium compound.

15. A device according to claim 14 wherein said compound is N, N'"'"''"'"'-dimethyl-2,7-diazapyrenium difluoroborate.

16. A device according to claim 2 wherein said compound is a pyrazidinium compound.

17. A device according to claim 16 wherein said compound is dipyrido(1,2- Alpha ;

2'"'"''"'"',1'"'"''"'"'-c)-pyrazidinium dibromide.

18. A device according to claim 2 wherein said compound is a 4, 4'"'"''"'"'-dipyridylium compound.

19. A device according to claim 18 wherein said compound is N, N'"'"''"'"'-dimethyl-4,4'"'"''"'"'-dipyridylium dichloride.

20. A device according to claim 18 wherein said compound is N, N'"'"''"'"'-dibenzyl-4,4'"'"''"'"'-dipyridylium dichloride.

21. A device according to claim 18 wherein said compound is poly-N,n-octylene-4,4'"'"''"'"'-dipyridylium dibromide.

22. A device according to claim 18 wherein said compound is poly-N,n-butylene-4,4'"'"''"'"'-dipyridylium dibromide.

23. In an enclosure provided with transparent means for transmitting light from an external source into said enclosure, the improvement which comprises positioning in coextensive relationship with said transparent means, a light-filtering device as defined in claim 2.