Light sources having a continuous broad emission wavelength and phosphor compositions useful therefor

• US 20030222268A1
• Filed: 02/21/2003
• Published: 12/04/2003
• Est. Priority Date: 05/31/2002
• Status: Abandoned Application

• Current Assignee: Sarnoff Corporation (SRI International, Inc.)
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: Tian, Yongchi, Yocom, Perry Niel
• Application Number:
  US10/372,004
• Publication Number:
  US 20030222268A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: C09K 11/584 with zinc or cadmium
• CPC Class Codes: C09K 11/676 Aluminates; Silicates
• CPC Class Codes: C09K 11/685 Aluminates; Silicates
• CPC Class Codes: C09K 11/77062 Silicates
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 33/502 Wavelength conversion materials

Abstract

Phosphor mixtures having a continuous emission wavelength of from about 400 to about 1500 nanometers and higher can be made from inorganic phosphors. Such phosphor mixtures can be used as light sources together with light sources or electron beam generators to provide a broad range of emission wavelength. Such phosphors can also be used to determine blood sugar levels in a human by emitting the phosphor light onto a light transmissive portion of the body, such as an ear lobe, and measuring glucose levels.

Claims

1. A light source having a broad, continuous emission wavelength of from about 435 nm up to 1600 nm and higher, comprised of a mixture of inorganic phosphors activated with copper or silver and co-activated with a halide or a trivalent ion when excited by a source of light energy.

4. A light source according to claim 1 wherein said inorganic phosphors are selected from the group consisting of solid solutions of zinc sulfide, zinc selenide, zinc telluride, cadmium sulfide, cadmium selenide, cadmium telluride, metal silicates, metal aluminum garnet and alumina.

6. A cathode ray tube comprising a glass envelope including an electron beam terminated with a screen wherein the screen is coated with a layer of the phosphor mixture of claim 1.

7. A light emitting diode coated with a phosphor layer mixture of claim 1, in turn coated with a light transparent layer.

15. A non-invasive method for monitoring glucose concentration in a diabetic patient using as a light source the phosphor mixture of claim 1, illuminating a portion of the body that will transmit light therethrough, and measuring the light transmission.

18. A method for monitoring glucose concentration in a diabetic patient using as a light source the phosphor mixture of claim 7.

2. A light source having a broad, continuous emission wavelength of from about 435 nm up to 1600 nm and higher, comprised of a mixture of II-VI phosphors activated with copper or silver and co-activated with a halide or a trivalent ion when excited by electron bombardment.

3. a light source according to claim 2 wherein said II-VI phosphors are of zinc and cadmium.

5. A light source according to claim 2 wherein said II-VI phosphors are selected from the group consisting of solid solutions of zinc sulfide, zinc selenide, zinc telluride, cadmium sulfide, cadmium selenide, cadmium telluride, metal silicates, metal aluminum garnet and alumina.

17. A method for monitoring glucose concentration in a diabetic patient using as a light source the phosphor mixture of claim 2.

8. A phosphor mixture comprising phosphors having an emission frequency varying from about 600 to about 1600 nm.

9. A phosphor mixture according to claim 8 wherein said phosphors comprise a mixture of strontium lithium silicate activated with divalent tin or manganese;

alumina activated with trivalent titanium;

cadmium sulfide activated with copper and magnesium silicate activated with chromium.

10. A phosphor mixture according to claim 8 wherein said phosphors comprise a mixture of calcium-magnesium silicate activated with divalent europium or manganese;

alumina activated with titanium;

cadmium sulfide activated with copper;

magnesium silicate activated with chromium; and

yttrium silicate activated with chromium.

11. A light emitting diode comprising a phosphor layer surrounding a light emitting diode wherein said phosphor layer is a phosphor mixture according to claim 9.

12. A light emitting diode according to claim 11 wherein said diode emits light in the ultraviolet light range of 300 to 420 nm.

13. A light emitting diode comprising a phosphor layer surrounding a light emitting diode wherein said phosphor layer is a phosphor mixture of claim 11.

14. A light source comprising a phosphor layer of claim 11 on a transparent substrate and an array of light emitting diodes of varying emission frequency mounted behind said substrate.

16. A method according to claim 12 wherein the body portion is an ear lobe.