Luminescent solid state status indicator

• US 3,873,979 A
• Filed: 09/28/1973
• Issued: 03/25/1975
• Est. Priority Date: 09/28/1973
• Status: Expired due to Term

• Current Assignee: David L. Keune, Magnus G. Craford
• Original Assignee: David L. Keune, Magnus G. Craford
• Inventors: Craford, Magnus G., Keune, David L.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US05/401,775
• Time in Patent Office: 543 Days
• Field of Search: 340/366R 313/18D,18R 317/235R
• US Class Current: 340/815.45
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/30 Driver circuits

Abstract

Luminescent indicators are disclosed employing at least two solid state light emitting devices packaged on a single header. The devices have one '"'"''"'"''"'"''"'"'state'"'"''"'"''"'"''"'"' at low currents or voltages and have another '"'"''"'"''"'"''"'"'state'"'"''"'"''"'"''"'"' at higher currents or voltages. A change of state of the devices may cause either the color of the status indicator to change or the light from the status indicator to change from continuous to flashing. The status indicator may provide a continuous change of state or a series of discrete levels or states. The light emitting devices are preferably semiconductor p-n junction devices with the logic or switching element of the devices packaged on the same header either as a separate circuit or incorporated into the light emitting semiconductor devices themselves. The status indicators have two or more terminals depending on the specific desired application.

Claims

1. A luminescent solid state status indicator characterized by:

at least first and second light emitting diodes mounted on a single header;

first terminal means on said header connected to both light emitting diodes and adapted to be connected to a first terminal of a direct current energizing voltage;

second terminal means on said header connected to at least one of the light emitting diodes and adapted to be connected to a second terminal of said direct current energizing voltage; and

said light emitting diodes being adapted to emit light the color of which shifts as a function of relative change in magnitude of said direct current energizing voltage.

2. A luminescent solid state status indicator as recited in claim 1 wherein at least one of said light emitting diodes comprises a red light emitting GaAsP diode.

3. A luminescent solid state status indicator as recited in claim 1 wherein one of said light emitting diodes is a green light emitting GaP diode and the other of said light emitting diodes is a red light emitting GaAsP diode.

4. A luminescent solid state status indicator as recited in claim 1 wherein said first light emitting diode is connected to said second terminal means by a resistor and said second light emitting diode is connected to said second terminal means by a third diode.

5. A luminescent solid state status indicator as recited in claim 4 wherein said first and second light emitting diodes are poled in the same direction, and emit different colors of light, and said first light emitting diode conducting at a lower value of voltage connected across said first and second terminal means than that required for conduction in said second light emitting diode as determined by the biasing characteristics of said third diode.

6. A luminescent solid state status indicator as recited in claim 5 wherein said third diode is a light emitting diode identical to said second light emitting diode.

7. A luminescent solid state status indicator as recited in claim 5 further comprising means for diffusing the light from said first and second light emitting Diodes.

8. A luminescent solid state status indicator as recited in claim 7 wherein said first light emitting diode is a green light emitting GaP diode and said second light emitting diode is a red light emitting GaAsP diode, and said diffusing means causes the light from said indicator to change from green through yellow -green, yellow, and orange to red as said energizing voltage increases.

9. A luminescent solid state status indicator as recited in claim 1 wherein said first light emitting diode is connected to said first terminal means by a first resistor and said second light emitting diode is connected to said first terminal means by said first resistor and a second resistor.

10. A luminescent solid state status indicator as recited in claim 9 wherein said second terminal means is connected to said first light emitting diode, and further comprising third terminal means on said header connected to said second light emitting diode and adapted to be connected to a source of voltage indicative of a condition to be monitored.

11. A luminescent solid state status indicator as recited in claim 10 wherein said first and second light emitting diodes emit different colors of light and have like poles connected to said first terminal means by said first resistor and said first and second resistors, respectively.

12. A luminescent solid state status indicator as recited in claim 11 further comprising means for diffusing the light from said first and second light emitting diodes.

13. A luminescent solid state status indicator as recited in claim 12 wherein said first light emitting diode is a green light emitting GaP diode and said second light emitting diode is a red light emitting GaAsP diode, said energizing voltage is a direct current voltage and said source of voltage is a direct current voltage variable from zero to a value equal in magnitude but opposite in polarity to said energizing voltage, and said diffusing means causes the light from said indicator to change from green through yellow - green, yellow, and orange to red as the magnitude of said source of voltage increases.