VARIABLE LIGHT-FILTERING DEVICE WITH A REDOX COMPOUND WHICH FUNCTIONS AS ITS OWN ELECTROLYTE
First Claim
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.
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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.
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Citations
23 Claims
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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.
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3. A device according to claim 2 wherein said layer contains an oxidizing agent.
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4. A device according to claim 2 including means for reversing the direction of current flow.
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5. A device according to claim 4 including means for automatically predetermining said direction of current flow.
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6. A device according to claim 2 wherein said layer comprises a solution of said redox compound in a light-transmitting solvent.
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7. A device accordiNg to claim 6 wherein said solvent is water.
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8. A device according to claim 6 wherein said solvent is an electrically stable organic liquid.
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9. A device according to claim 2 wherein said layer comprises said redox compound in a light-transmitting solid matrix.
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10. A device according to claim 9 wherein said matrix is a gel.
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11. A device according to claim 9 wherein said matrix is a polymer.
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12. A device according to claim 2 wherein said redox compound is a polymer.
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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.
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14. A device according to claim 2 wherein said compound is a diazapyrenium compound.
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15. A device according to claim 14 wherein said compound is N, N'"'"''"'"'-dimethyl-2,7-diazapyrenium difluoroborate.
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16. A device according to claim 2 wherein said compound is a pyrazidinium compound.
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17. A device according to claim 16 wherein said compound is dipyrido(1,2- Alpha ;
- 2'"'"''"'"',1'"'"''"'"'-c)-pyrazidinium dibromide.
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18. A device according to claim 2 wherein said compound is a 4, 4'"'"''"'"'-dipyridylium compound.
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19. A device according to claim 18 wherein said compound is N, N'"'"''"'"'-dimethyl-4,4'"'"''"'"'-dipyridylium dichloride.
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20. A device according to claim 18 wherein said compound is N, N'"'"''"'"'-dibenzyl-4,4'"'"''"'"'-dipyridylium dichloride.
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21. A device according to claim 18 wherein said compound is poly-N,n-octylene-4,4'"'"''"'"'-dipyridylium dibromide.
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22. A device according to claim 18 wherein said compound is poly-N,n-butylene-4,4'"'"''"'"'-dipyridylium dibromide.
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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.
Specification