Adaptive infrared modulator

• US 5,774,255 A
• Filed: 09/23/1996
• Issued: 06/30/1998
• Est. Priority Date: 09/23/1996
• Status: Expired due to Term

• Current Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Original Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Inventors: Howard, Bruce M.
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): Robbins, Thomas
• Application Number:
  US08/717,758
• Time in Patent Office: 645 Days
• Field of Search: 359/265, 359/267
• US Class Current: 359/267
• CPC Class Codes: B64G 1/50 for temperature control
• CPC Class Codes: F24S 50/80 for controlling collection or absorption of solar radiation
• CPC Class Codes: G02F 1/1508 using a solid electrolyte
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers

Abstract

A reversible electrodeposition electrochromic infrared modulator for modulating infrared energy is provided. The modulator includes a working electrode having an infrared transparent substrate with first and second major surfaces. A conductive layer is disposed on the second major surface of the substrate. A counter electrode is spaced from the working electrode and a sealing assembly hermetically seals the working and counter electrodes with a cavity defined therebetween. An electrolyte material containing an electrochromic material is disposed within the cavity. A reversible power source is coupled to the working and the counter electrodes for providing a reversible voltage potential between the working and the counter electrodes. A thin film of the electrochromic material plates the conductive layer of the working electrode in response to an on state voltage potential between the working and the counter electrodes. The film of the electrochromic material increases the reflectance of infrared energy incident upon the first major surface of the infrared transparent substrate.

Claims

1. A reversible electrodeposition electrochromic infrared modulator system for a spacecraft, comprising:

a) a thermal radiator associated with a spacecraft; and

b) an electrochromic modulator thermally connected to said thermal radiator, said modulator including;

a working electrode including an infrared transparent substrate having a first major surface, a second major surface, and a conductive layer disposed on the second major surface of the substrate;

a counter electrode spaced from the working electrode;

a sealing assembly for hermetically sealing the working and the counter electrodes with a cavity defined therebetween;

a gel electrolyte material disposed within the cavity, the gel electrochromic material including a reversible electrodeposition material; and

a reversible power source coupled to the working and the counter electrodes for providing a reversible voltage potential between the working and the counter electrodes, whereby a film of the electrochromic material plates the conductive layer in response to an on state voltage potential between the working and the counter electrodes such that reflectance of infrared energy incident on the first major surface of the substrate is increased;

the system exhibiting a reflectance modulation of;

(i) about 30% to 60% in the 8-12 μ

m wavelength region; and

(ii) about 35% to 55% in the 2-8 μ

m wavelength region.

2. The system of claim 1, further comprising:

a plurality of conductive grid patterns disposed throughout the conductive layer, whereby the conductive grid patterns increase the conductivity of the working electrode.

3. The system of claim 2, wherein the conductive grid patterns are formed from a noble metal.

4. The system of claim 1, wherein each of the conductive grid patterns includes a plurality of intersecting horizontally and vertically aligned conductive members.

5. The system of claim 1, further comprising:

an antireflection coating disposed on the first major surface of the working electrode for reducing reflection of the energy incident on the first major surface over a predetermined wavelength;

the system exhibiting a reflectance modulation of from about 30% to 87% in the 8-12 μ

m wavelength region.

6. The system of claim 5, wherein a reflectance modulation of about 80%, at about 10 μ

m wavelength, occurs in about 70 seconds.

7. The system of claim 1, wherein the electrochromic material includes nickel.

8. The system of claim 1, wherein the infrared transparent substrate is formed from a material selected from the group consisting of zinc sulfide (ZnS), zinc selenide (ZnSe), infrared transparent glass, silicon, sapphire, polyethylene and mixtures thereof.

9. The system of claim 1, wherein the conductive layer is indium tin oxide.

10. A reversible electrodeposition electrochromic infrared modulator for thermally connecting with a thermal radiator of a spacecraft, comprising:

a working electrode including an infrared transparent substrate having a first major surface, a second major surface, and a conductive layer disposed on the second major surface of the substrate;

a plurality of conductive grid patterns disposed throughout the conductive layer for increasing the conductivity of the working electrode;

an antireflection coating disposed on the first major surface of the working electrode for reducing reflection of received energy over a predetermined wavelength;

a counter electrode spaced from the working electrode;

a sealing assembly for hermetically sealing the working and the counter electrode with a cavity defined therebetween;

an electrolyte material disposed within the cavity, the electrolyte material containing an electrochromic material including a reversible electrodeposition material; and

a reversible power source coupled to the working and the counter electrodes for providing a reversible voltage potential between the working and the counter electrodes, whereby a film of the electrochromic material plates the conductive layer in response to an on state voltage potential between the working and counter electrodes such that reflectance of infrared energy incident on the first major surface of the substrate is increased and whereby the film of the electrochromic material is stripped from the conductive layer in response to reversed voltage potential between the working and counter electrodes such that the reflectance of the infrared energy is decreased;

said modulator exhibiting a reflectance modulation of;

(i) about 30% to 60% in the 8-12 μ

m wavelength region; and

(ii) about 35% to 55% in the 2-8 μ

m wavelength region.

11. The modulator of claim 10, wherein each of the conductive grid patterns includes a plurality of intersecting horizontally and vertically aligned conductive members.

12. The modulator of claim 10, wherein the conductive grid pattern members are formed from a noble metal.

13. The modulator of claim 10, wherein the electrochromic material includes nickel.

14. The modulator of claim 10, wherein the infrared transparent substrate is formed from a material selected from the group consisting of zinc sulfide (ZnS), zinc selenide (ZnSe), infrared transparent glass, silicon, sapphire, polyethylene and mixtures thereof.

15. The modulator of claim 10, wherein the conductive layer is indium tin oxide.

16. A thermal control system, comprising:

a thermal radiator associated with a spacecraft for controlling thermal operating conditions of the spacecraft;

a reversible electrodeposition electrochromic infrared modulator disposed on an outer surface of the radiator, the modulator including;

(a) a working electrode including an infrared transparent substrate having a first major surface, a second major surface, and a conductive layer disposed on the second major surface of the substrate;

the infrared transparent substrate being formed from a material selected from the group consisting of zinc sulfide (ZnS), zinc selenide (ZnSe), infrared transparent glass, silicon, sapphire, polyethylene and mixtures thereof;

(b) a plurality of conductive grid patterns disposed throughout the conductive layer, whereby the conductive grid patterns increase the conductivity of the working electrode;

(c) an antireflection coating disposed on the first major surface of the working electrode for reducing reflection of the energy incident on the first major surface over a predetermined wavelength;

(d) a counter electrode spaced from the working electrode;

(e) a sealing assembly for hermetically sealing the working and the counter electrode with a cavity defined therebetween;

(f) a gel electrolyte material disposed within the cavity, the gel electrolyte material containing an electrochromic material incorporating nickel for reversible electrodeposition; and

(g) a reversible power source coupled to the working and the counter electrodes for providing a reversible voltage potential between the working and the counter electrodes, whereby a film of the electrochromic material plates the conductive layer in response to an on state voltage potential between the working and the counter electrodes such that reflectance of infrared energy incident on the first major surface of the substrate is increased;

the system exhibiting a reflectance modulation of;

(i) about 30% to 60% in the 8-12 μ

m wavelength region; and

(ii) about 35% to 55% in the 2-8 μ

m wavelength region.

17. The system of claim 16, wherein the infrared transparent substrate is zinc sulfide.

18. The system of claim 16, wherein the system exhibits a reflectance modulation of from about 30% to 87% in the 8-12 μ

m wavelength region.

19. The system of claim 18, wherein a reflectance modulation of about 80%, at about 10 μ

m wavelength, occurs in about 70 seconds.