Non-linear light-emitting load current control

• US 6,400,102 B1
• Filed: 06/07/2001
• Issued: 06/04/2002
• Est. Priority Date: 12/23/1999
• Status: Expired due to Term

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Ghanem, Mohamed Sherif
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): TRAN, THUY V
• Application Number:
  US09/875,027
• Publication Number:
  US 20020030455A1
• Time in Patent Office: 362 Days
• Field of Search: 315/291, 315/224, 315/247, 315/311, 315/209.R, 315/219, 315/272, 315/307, 307/52, 307/60, 363/20, 363/21, 363/89
• US Class Current: 315/291
• CPC Class Codes: G01R 31/2653 using electron beams
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/18 using temperature feedback
• CPC Class Codes: H05B 45/385 using flyback topology

Abstract

A sensor circuit detects a current supplied to a set of light-emitting diodes and produces a current reading dependent on the temperature of .operation of these light-emitting diodes. The sensor circuit comprises first and second serially interconnected resistors also connected in series with the set of light-emitting diodes. The sensor circuit also comprises a temperature-dependent impedance connected in parallel with one of the first and second resistors. At least a portion of the current through the set of light-emitting diodes flows through the sensor circuit to enable the first and second serially interconnected resistors and the temperature-dependent impedance to produce a variable voltage signal representative of the current through the set of light-emitting diodes, this variable voltage signal being dependent upon temperature. The above sensor circuit finds application in a substantially constant intensity light source.

Claims

1. A sensor circuit for detecting a current supplied to a non-linear light-emitting load and for producing a voltage signal dependent on a temperature of operation of the light-emitting load, said sensor circuit comprising:

c) first and second serially interconnected resistors also connected in series with the light-emitting load; and

d) a variable impedance connected in parallel with one of said first and second resistors, said variable impedance having an impedance value which varies with the temperature of operation of the light-emitting load;

whereby at least a portion of the current through the light-emitting load flows through the sensor circuit to enable said first and second serially interconnected resistors and said variable impedance to produce a variable voltage signal representative of the current flowing through the light-emitting load and dependent on said temperature of operation.

2. A light source as defined in claim 1, wherein the light-emitting load comprises a set of light-emitting diodes.