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US 6,680,834 B2Granted
Apparatus and method for controlling LED arrays
AssigneeHoneywell International Inc.
InventorMarion S. Williams
Life of this patent
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Abstract
A high precision, high efficiency controller for LED devices such as LED arrays includes a current limiter, driver and buffer.
Claims12
An apparatus for controlling the brightness of an LED array comprising:
- a current limiter disposed between the LED array and a power supply, for limiting an amount of current supplied to the entire LED array;
- and
- a controller having an input coupled to receive a plurality of control signals and having an output coupled to the LED array for controlling the brightness of the LED array in accordance with said plurality of control signals.
A display illuminated using a plurality of LEDs, the display comprising:
- (a) an array of LED devices wherein said array consists of:
- (i) a plurality of individual LED devices connected in series to form a string;
- (ii) a plurality of said strings connected in parallel to form said array;
- (b) a current limiter disposed between a power supply and said array for limiting an amount of current supplied to said array;
- and
- (c) a controller having an input adapted to receive a plurality control signals and an output coupled to said array for controlling a brightness of said array in accordance with said control signals.
3 more elements
A display illuminated using a plurality of LEDs, the display comprising:
- (a) an array of LED devices wherein said array consists of:
- (i) a plurality of individual LED devices connected in series to form a string;
- (ii) a plurality of said strings connected in parallel to form said array;
- (b) a current limiter disposed between a power supply and said array for limiting an amount of current supplied to said array;
- and
- (c) a controller having an input adapted to receive a plurality of control signals and an output coupled to said array for controlling a brightness of said array in accordance with said control signals, wherein said controller comprises:
- (i) a drive circuit coupled to said output;
- and
- (ii) a buffer disposed between said drive circuit and said input for buffering said plurality of signals.
6 more elements
A circuit for controlling the brightness of an LED array, the circuit comprising:
- (a) a current limiter having:
- (i) a current limiter input coupled to a first pole of a power supply;
- (ii) a PNP transistor;
- having a collector coupled to said input;
- (iii) a first resistor disposed between said input and an emitter of said PNP transistor;
- (iv) a second resistor disposed between said emitter of said PNP transistor and ground;
- (v) a first FET having a gate coupled to said emitter of said PNP transistor;
- (vi) a third resistor disposed between said input and a source of said first FET transistor;
- (vii) a fourth resistor disposed between a base of said PNP transistor and said source of said first FET;
- and
- (viii) a current limiter output coupled to a first pole of the LED array and to a drain of said first FET;
- (b) a driver having a driver input adapted to receive a plurality of signals useful for controlling a brightness of the LED array and having a driver output coupled to a second pole of the LED array, the driver further including:
- (i) a push/pull buffer having a buffer input coupled to said driver input and a buffer output;
- (ii) a second FET having a source coupled to ground, a drain coupled to said driver output and a gate;
- and
- (iii) a fifth resistor disposed between said buffer output and said gate of said second FET.
13 more elements
A method for controlling an LED array comprising the steps of:
- receiving a control signal;
- boosting a current of said control signal using a buffer that operates with a response time at least as fast as the shortest duration pulse of said control signal to obtain a buffered control signal;
- supplying said buffered control signal to a driver to drive the LED array according to said buffered control signal;
- and
- limiting an amount of current supplied to the entire array while maintaining continued operation of the LED array.
2 more elements
A method for controlling the brightness of an LED array comprising the steps of:
- supplying power to the LED array in accordance with a control signal;
- and
- preventing a magnitude of an amount of current supplied to the entire LED array from exceeding a predetermined threshold value while maintaining continued operation of the LED array.
A method for controlling the brightness of an LED device comprising the steps of:
- receiving a pulse width modulated control signal representative of a desired LED device brightness;
- supplying power to the LED device in accordance with said pulse width modulated control signal;
- and
- preventing a magnitude of current drawn by the LED device from exceeding a predetermined threshold value while maintaining continued operation of the LED device.
1 more element
Dependencies are inferred from the claim text.