Solid state lighting apparatus with compensation bypass circuits and methods of operation thereof
First Claim
1. A lighting apparatus comprising:
- a string of serially-connected light emitting devices; and
a bypass circuit configured to bypass at least one light-emitting device of the string of serially-connected light emitting devices based on a color point of the at least one light emitting device, to sense a current in the string and to individually vary a bypass current conducted by the bypass circuit in proportion to the sensed current in the string and concurrently responsive to a temperature sense signal.
3 Assignments
0 Petitions
Accused Products
Abstract
A lighting apparatus includes a string of serially-connected light emitting devices and a bypass circuit coupled to first and second nodes of the string and configured to variably conduct a bypass current around at least one of the light-emitting devices responsive to a temperature and/or a total current in the string. In some embodiments, the bypass circuit includes a variable resistance circuit coupled to the first and second nodes of the string and configured to variably conduct the bypass current around the at least one of the light-emitting devices responsive to a control voltage applied to a control node and a compensation circuit coupled to the control node and configured to vary the control voltage responsive to a temperature and/or total string current.
-
Citations
26 Claims
-
1. A lighting apparatus comprising:
-
a string of serially-connected light emitting devices; and a bypass circuit configured to bypass at least one light-emitting device of the string of serially-connected light emitting devices based on a color point of the at least one light emitting device, to sense a current in the string and to individually vary a bypass current conducted by the bypass circuit in proportion to the sensed current in the string and concurrently responsive to a temperature sense signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. An apparatus for controlling a string of serially-connected light emitting devices, the apparatus comprising:
-
a variable resistance circuit coupled to first and second nodes of the string and configured to variably conduct a bypass current around the at least one of the light-emitting devices responsive to a control voltage applied to a control node; and a temperature compensation circuit coupled to the control node and configured to vary the control voltage responsive to a temperature and comprising a voltage divider comprising; a first resistor having a first terminal coupled to the first node of the string and a second terminal coupled to the control node; and a second resistor having a first terminal coupled to the second node of the string and a second terminal coupled to the control node, wherein at least one of the first and second resistors comprises a thermistor.
-
-
10. A lighting apparatus comprising:
-
a string of serially-connected light emitting devices; and a bypass circuit coupled to first and second nodes of the string and configured to sense a total current in the string and to individually variably partially bypass at least one of the light-emitting devices based on a color point of the at least one of the light emitting devices and in proportion to the sensed total current of the string responsive to the sensed total current of the string. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
-
-
19. An apparatus for controlling a string of serially-connected light emitting devices, the apparatus comprising:
-
a variable resistance circuit coupled to first and second nodes of the string of serially-connected light emitting devices and configured to individually variably partially bypass at least one of the light-emitting devices based on a color point of the at least one of the light emitting devices and responsive to a control voltage applied to a control node of the variable resistance circuit; and a bypass control circuit configured to sense a total current in the string and to vary the control voltage responsive to the sensed total current through the string such that a bypass current through the variable resistance circuit varies in proportion to the sensed total current. - View Dependent Claims (20, 21, 22)
-
-
23. A lighting apparatus comprising:
-
a string of serially-connected light emitting devices; a variable resistance circuit comprising; a bipolar junction transistor having a collector terminal coupled to a first node of the string; and a first resistor coupled between an emitter terminal of the bipolar junction transmitter and a second node of the string; and a bypass control circuit comprising; a second resistor having a first terminal coupled to the first node of the string and a second terminal coupled to the base terminal of the bipolar junction transistor; a third resistor having a first terminal coupled to the second node of the string; and a diode having a first terminal coupled to a second node of the third resistor and a second terminal coupled to the base terminal of the bipolar junction transistor. - View Dependent Claims (24, 25)
-
-
26. A lighting apparatus comprising:
-
a string of serially-connected light emitting devices; and bypass means for sensing a temperature and a current through the string and for controlling a color point of a string of serially-connected light emitting devices through selective bypass of at least one of the light emitting devices based on a color point of the at least one of the light emitting devices concurrently responsive to the sensed temperature and the sensed current through the string.
-
Specification