LED light strip with brightness/current draw control circuitry

• US 5,661,374 A
• Filed: 08/15/1996
• Issued: 08/26/1997
• Est. Priority Date: 12/14/1994
• Status: Expired due to Term

• Current Assignee: Astronics Corporation
• Original Assignee: Astronics Corporation
• Inventors: Livingston, Douglas J., Cassidy, Robert E.
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): KINKEAD, ARNOLD M
• Application Number:
  US08/698,482
• Time in Patent Office: 376 Days
• Field of Search: 362/391, 362/249, 362/800, 362/219, 362/153, 323/254, 323/266, 323/292, 323/269, 323/902, 323/273, 323/272, 323/265, 315/291, 315/307, 315/121, 315/122, 315/185 R, 315/312
• US Class Current: 315/307
• CPC Class Codes: G05F 1/577 for plural loads
• CPC Class Codes: H05B 39/044 continuously H05B39/042 takes precedence
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A current consumption control system for controlling the current draw of an electric power-consuming device, e.g., a modular strip lighting unit for a lighting system including at least one said unit, in which the strip lighting unit includes at least one light source element operatively coupled to a lighting circuit. The lighting circuit may illustratively comprise at least one pair of primary conduction lines connectable to a voltage source, and coupled in electrical circuit relationship with a current regulating circuit. The current regulating circuit includes an operational amplifier which is coupled with the primary conduction lines to generate a reference voltage, and which is coupled with positve and negative current input lines, with at least one power-consuming device coupled to the current output of the operational amplifier, and to the negative current input line. In such arrangement, the operational amplifier compares (i) the reference voltage to (ii) the voltage differential between the positive current input and the negative current input of the operational amplifier, and responsively adjusts current at the current output of the operational amplifier to the power-consuming element, to maintain a selected power consumption level by the electrical power-consuming element, independent of the input voltage across the primary conduction lines.

Claims

1. A current consumption control circuit for controlling the current consumption of an electrical power-consuming device in an electrically powered system including at least one pair of primary conduction lines connectable to a voltage source for maintaining a voltage differential between said at least one pair of primary conduction lines, one line of said at least one pair of primary conduction lines therein being a positive primary conduction line and the other line of said at least one pair of primary conduction lines being a negative primary conduction line, with the positive primary conduction line and the negative primary conduction line being coupled in electrical circuit relationship to the current consumption control circuit, said current consumption control circuit comprising:

an operational amplifier including a positive reference voltage input, a negative reference voltage input, a positive current input, a negative current input, and a current output;

a positive reference voltage input line joining the positive reference voltage input of the operational amplifier with the positive primary conduction line;

a negative reference voltage input line joining the negative reference voltage input of the operational amplifier with the negative primary conduction line;

a positive current input line comprising at least one resistor and joining the positive current input of the operational amplifier to the positive primary conduction line;

a negative current input line comprising at least one resistor and joining the negative current input of the operational amplifier to the negative primary conduction line, and

at least one output conduction line having, in series, at least one electric power-consuming device and having first and second ends, with the first end of the output conduction line being joined to the current output of the operational amplifier, and with the second end of the output conduction line being joined to the negative current input line such that the at least one electric power-consuming device has first and second ends and is disposed in series between the current output and the negative current input by having its first end connected to said current output and its second end connected to said negative current input;

wherein the operational amplifier is constructed and arranged to compare (i) a reference voltage differential between the positive reference voltage input and the negative reference voltage input of the operational amplifier, to (ii) the voltage differential between the positive current input and the negative current input of the operational amplifier, and to responsively adjust current from the current output of said operational amplifier to the output conduction line having the first end of said at least one electric power-consuming device connected thereto so as to maintain a selected current consumption level from the at least one electric power-consuming device independent of input voltage across the pair of primary conduction lines; and

whereby voltage across the operational amplifier reference voltage inputs of the current consumption control circuit and the current consumption of the electric power-consuming device are unaffected by short-circuit failure of other electric power-consuming devices arranged in series therewith in the circuit or by short-circuit failure of other current consumption control circuits in parallel therewith.

2. A current consumption control circuit for controlling the current consumption of an electrical power-consuming device in an electrically powered system including at least one pair of primary conduction lines connectable to a voltage source for maintaining a voltage differential between said at least one pair of primary conduction lines, one line of said at least one pair of primary conduction lines therein being a positive primary conduction line and the other line of said at least one pair of primary conduction lines being a negative primary conduction line, with the positive primary conduction line and the negative primary conduction line being coupled in electrical circuit relationship to the current consumption control circuit, said current consumption control circuit comprising:

an operational amplifier including a positive reference voltage input, a negative reference voltage input, a positive current input, a negative current input, and a current output;

a positive reference voltage input line joining the positive reference voltage input of the operational amplifier with the positive primary conduction line;

a negative reference voltage input line joining the negative reference voltage input of the operational amplifier with the negative primary conduction line;

a positive current input line comprising at least one resistor and joining the positive current input of the operational amplifier to the positive primary conduction line, said positive current input line being coupled to the negative primary conductive line by a branch conductive line with a diode therein, wherein the diode is forwardly biased toward the negative primary conductive line, to provide a reference voltage differential;

a negative current input line comprising at least one resistor and joining the negative current input of the operational amplifier to the negative primary conduction line, and

at least one output conduction line having in series, at least one electric power-consuming device and having first and second ends, with the first end of the output conduction line being joined to the current output of the operational amplifier, and with the second end of the output conduction line bring joined to the negative current input line such that the at least one electric power-consuming device is disposed in series between the current output and the negative current input;

wherein the operational amplifier is constructed and arranged to compare (i) said reference voltage differential between the positive reference voltage input and the negative reference voltage input of the operational amplifier, to (ii) the voltage differential between the positive current input and the negative current input of the operational amplifier, and to responsively adjust current from the current output of said operational amplifier to the output conduction line to maintain a selected current consumption level from the at least one electric power-consuming device independent of input voltage across the pair of primary conduction lines; and

whereby voltage across the operational amplifier reference voltage inputs of the current consumption control circuit and the current consumption of rite electric power-consuming device are unaffected by short-circuit failure of other electric power-consuming devices arranged in series therewith in the circuit or by short-circuit failure of other current consumption control circuits in parallel therewith.

3. A current consumption control circuit according to claim 2, wherein the diode comprises a silicon diode.

4. A current consumption control circuit according to claim 2, which is symmetric about the postive current input line and the branch conductive line, comprising a second operational amplifier including a positive reference voltage input, a negative reference voltage input, a positive current input, a negative current input, and a current output, a second positive reference voltage input line joining the positive reference voltage input of the second operational amplifier with the positive primary conduction line, a second negative reference voltage input line joining the negative reference voltage input of the second operational amplifier with the negative primary conduction line, a second negative current input line comprising at least one resistor and joining the negative current input of the second operational amplifier to the negative primary conduction line, and at least one second output conduction line coupled to at least one second electric power-consuming element and having first and second ends, with the first end of the second output conduction line being joined to the current output of the second operational amplifier, and with the second end of the second output conduction line being joined to the second negative current input line.

5. A current consumption control circuit according to claim 2, wherein an integrated circuit operational amplifier chip comprises the operational amplifier.

6. A current consumption control circuit according to claim 2, further comprising a voltage source.

7. A current consumption control circuit according to claim 6, wherein the voltage source comprises a battery.

8. A modular strip lighting unit constructed and arranged the use in a lighting system which includes at least one said modular strip lighting unit, said modular strip lighting unit including at least one light source element operatively coupled to a lighting circuit, with said lighting circuit comprising:

at least one pair of primary conduction lines connectable to a voltage source for maintaining a voltage differential between said at least one pair of primary conduction lines, one line of said at least one pair of primary conduction lines therein being a positive primary conduction line and the other line of said at least one pair of primary conduction lines being a negative primary conduction line, with the positive primary conduction line and the negative primary conduction line being coupled in electrical circuit relationship to a current regulating circuit;

said current regulating circuit comprising;

an operational amplifier including a positive reference voltage input, a negative reference voltage input, a positive current input, a negative current input, and a current output;

a positive reference voltage input line joining the positive reference voltage input of file operational amplifier with the positive primary conduction line;

a negative reference voltage input line joining the negative reference voltage input of the operational amplifier with the negative primary conduction line;

a positive current input line comprising at least one resistor and joining the positive current input of the operational amplifier to the positive primary conduction line;

a negative current input line comprising at least one resistor and joining the negative current input of the operational amplifier to the negative primary conduction line, and

at least one light source conduction line having, in series, at least one light source element and having first and second ends, with the first end of the at least one light source conduction line being joined to the current output of the operational amplifier, and with the second end of the at least one light source conduction line being joined to the negative current input line such that the at least one light source element has first and second ends and is disposed in series between the current output and the negative current input by having its first end connected to said current output and its second end connected to said negative current input;

wherein the operational amplifier is constructed and arranged to compare (i) a reference voltage differential between the positive reference voltage input and the negative reference voltage input of the operational amplifier, to (ii) the voltage differential between the positive current input and the negative current input of the operational amplifier, end to responsively adjust current from the current output of said operational amplifier to said at least one light source conduction line having the first end of said at least one light source element connected thereto so as to maintain a selected illumination level from said at least one light source element independent of input voltage across said pair of primary conduction lines; and

whereby voltage across the operational amplifier reference voltage inputs, of the current consumption control circuit and the current consumption of the at least one light source element are unaffected by short-circuit failure of other light source elements arranged in series therewith in the circuit or by short-circuit failure of other current consumption control circuits in parallel therewith.

9. A modular strip lighting unit constructed and arranged for use in a lighting system which includes at least one said modular strip lighting unit, said modular strip lighting unit including at least one light source element operatively coupled to a lighting circuit, with said light circuit comprising:

at least one pair of primary conduction lines connectable to a voltage source for maintaining a voltage differential between said at least one pair of primary conduction lines, one line of said at least one pair of primary conduction lines therein being a positive primary conduction line and the other line of said at least one pair of primary conduction lines being a negative primary conduction line, with the positive primary conduction line and the negative primary conduction line being coupled in electrical circuit relationship to a current regulating circuit;

said current regulating circuit comprising;

an operational amplifier including a positive reference voltage input, a negative reference voltage input, a positive current input, a negative current input, and a current output;

a positive reference voltage input line joining the positive reference voltage input of the operational amplifier with the positive primary conduction line;

a negative reference voltage input line joining the negative reference voltage input of the operational amplifier with the negative primary conduction line;

a positive current input line comprising at least one resistor and joining the positive current input of the operational amplifier to the positive primary conduction line, said positive current input line being coupled to the negative primary conductive line by a branch conductive line with a diode therein, wherein the diode is forwardly biased toward the negative primary conductive line, to provide a reference voltage differential;

a negative current input line comprising at least one resistor and joining the negative current input of the operational amplifier to the negative primary conduction line, and

at least one light source conduction line having, in series, at least one light source element and having first and second ends, with the first end of the at least one light source conduction line being joined to the current output of the operational amplifier, and with the second end of the at least one light source conduction line being joined to negative current input line such that the at least one light source element is disposed in series between the current output and the negative current input;

wherein the operational amplifier is constructed and arranged to compare (i) said reference voltage differential between the positive reference voltage input and the negative reference voltage input of the operational amplifier, to (ii) the voltage differential between the positive current input and the negative current input of the operational amplifier, and to responsively adjust current from the current output of said operational amplifier to said at least one light source conduction line to maintain a selected illumination level from said at least one light source element independent of input voltage across said pair of primary conduction lines; and

whereby voltage across the operational amplifier reference voltage inputs of the current consumption control circuit and the current consumption of the light source element are unaffected by short-circuit failure of other light source elements arranged in series therewith in the circuit or by short-circuit failure of other current consumption control circuits in parallel therewith.

10. A modular strip lighting unit according to claim 9, wherein the diode comprises a silicon diode.

11. A modular strip lighting unit according to claim 9, further comprising at least one second light source element, and wherein said current regulating circuit is symmetric about the postive current input line and the branch conductive line, comprising a second operational amplifier including a positive reference voltage input, a negative reference voltage input, a positive current input, a negative current input, and a current output, a second positive reference voltage input line joining the positive reference voltage input of the second operational amplifier with the positive primary conduction line, a second negative reference voltage input line joining the negative reference voltage input of the second operational amplifier with the negative primary conduction line, a second negative current input line comprising at least one resistor and joining the negative current input of the second operational amplifier to the negative primary conduction line, and at least one second output conduction line coupled to at least one second light source element and having first and second ends, with the first end of the second output conduction line being joined to the current output of the second operational amplifier, and with the second end of the second output conduction line being joined to the second negative current input line.

12. A modular strip lighting unit according to claim 9, wherein an integrated circuit operational amplifier chip comprises the operational amplifier.

13. A modular strip lighting unit according to claim 9, further comprising a voltage source.

14. A modular strip lighting unit according to claim 13, wherein the voltage source comprises a battery.

15. A modular strip lighting unit according to claim 9, wherein said pair of primary conduction lines is constructed and arranged to be selectively coupleable in series or parallel relationship with another modular strip lighting unit.

16. A modular strip lighting unit according to claim 9, wherein the at least one light source element is selected from the group consisting of light emitting diodes, incandescent lamps, cold cathode lamps, hot cathode lamps, electroluminescent phosphor elements, and combinations thereof.

17. A modular strip lighting unit according to claim 9, wherein said at least one light source element comprises at least one light emitting diode.

18. A modular strip lighting unit according to claim 9, wherein said at least one light source element comprises a multiplicity of light emitting diodes in series relationship with one another.

19. A modular strip lighting unit according to claim 9, comprising an electroluminescent lamp including a layer of electroluminescent phosphor material fixedly positioned by a polymer binder between two conductive layers at least one of which is transparent, said electroluminescent lamp being operable by application of an alternating electric field across the conductive layers to cause the electroluminescent phosphor material to become excited and emit electrons in the visible light spectrum.

20. A modular strip lighting unit according to claim 9, comprising an elongate casing, wherein said at least one light source element comprises a sequence of spaced-apart light emitting sources, with the modular strip lighting unit being interconnectable with other modular strip lighting units, in series or parallel relationship, to form multi-unit extended lighting system assemblies for illumination of a specific environment.

21. A multi-module strip lighting assembly, comprising a plurality of modular strip lighting units each of which is interconnected with at least one other modular strip lighting unit in the assembly, and wherein each of said modular strip lighting units includes at least one light source element operatively coupled to a lighting circuit, with said lighting circuit comprising:

at least one pair of primary conduction lines connectable to a voltage source for maintaining a voltage differential between said at least one pair of primary conduction lines, one line of said at least one pair of primary conduction lines therein being a positive primary conduction line and the other line of said at least one pair of primary conduction lines being a negative primary conduction line, with the positive primary conduction line and the negative primary conduction line being coupled in electrical circuit relationship to a current regulating circuit;

said current regulating circuit comprising;

an operational amplifier including a positive reference voltage input, a negative reference voltage input, a positive current input, a negative current input, and a current output;

a positive reference voltage input line joining the positive reference voltage input of the operational amplifier with the positive primary conduction line;

a negative reference voltage input line joining the negative reference voltage input of the operational amplifier with the negative primary conduction line;

a positive current input line comprising at least one resistor and joining the positive current input of the operational amplifier to the positive primary conduction line;

a negative current input line comprising at least one resistor and joining the negative current input of the operational amplifier to the negative primary conduction line, and

at least one light source conduction line having, in series, at least one light source clement and having first and second ends, with the first end of the at least one light source conduction line being joined to the current output of the operational amplifier, and with the second end of the at least one light source conduction line being joined to the negative current input line such that the at least one light source element has first and second ends and is disposed in series between the current output and the negative current input by having its first end connected to said current output and its second end connected to said negative current input;

wherein the operational amplifier is constructed and arranged to compare (i) a reference voltage differential between the positive reference voltage input and the negative reference voltage input of the operational amplifier, to (ii) the voltage differential between the positive current input and the negative current input of the operational amplifier, and to responsively adjust current from the current output of said operation amplifier to said light source conduction line having the first end of said at least one light source element connected thereto so as to maintain a selected illumination level from said at least one light source element independent of input voltage across said pair of primary conduction lines; and

whereby voltage across the operational amplifier reference voltage inputs of the current consumption control circuit and the current consumption of the light source element are unaffected by short-circuit failure of other light source elements arranged in series therewith in the circuit or by short-circuit failure of other current consumption control circuits in parallel therewith.

22. A method of controlling the current consumption of a plurality of current-consuming devices each having first and second ends which are arranged in series by means of an operational amplifier comprising:

establishing a reference voltage and inputting same across reference voltage inputs of the operational amplifier;

inputting a reference current at a positive current input of said operational amplifier;

coupling said first end of said series of current-consuming devices to an output of said operational amplifier; and

coupling said second end of said series of current-consuming devices to a negative current input of said operational amplifier,

such that the current across the current consuming devices is maintained at a predetermined level; and

whereby voltage across the operational amplifier reference voltage inputs and the current consumption of the electric power-consuming device are unaffected by short-circuit failure of other electric power-consuming devices arranged in series therewith or by short-circuit failure of other current consumption control circuits in parallel therewith.

23. A method according to claim 22, wherein the current-consuming device comprises an illumination element.

24. A method according to claim 22, wherein the current-consuming device comprises at least one light-emitting diode.