Method and apparatus for controlling visual enhancement of luminent devices

• US 20050099144A1
• Filed: 11/08/2004
• Published: 05/12/2005
• Est. Priority Date: 02/06/2003
• Status: Active Grant

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: CEYX Technologies Incorporated
• Inventors: Sanchez, Jorge
• Granted Patent: US 7,151,345 B2
• Time in Patent Office: Days
• US Class Current: 315/312
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: H05B 41/2822 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
• CPC Class Codes: H05B 41/3922 and measurement of the incident light

Abstract

The disclosed embodiments provide a method and apparatus for visual enhancement of liquid crystal displays. A microprocessor or embedded microcontroller associated with visual enhancement circuit modules allows a single inverter to control the intensity of illumination for an array of multiple CCFLs. The microcontroller continuously senses the operating currents of every lamp and adjusts for variations in illumination of individual lamps by parallel switching of capacitance that ensures an equal current is applied to each lamp. The microcontroller produces the appropriate control signals and executes a digital servo control algorithm to modify the currents for carrying out the luminance adjustments.

Claims

1. A method of current control for multiple luminent devices comprising:

sensing individual output information for each luminent device of a multiple device array;

processing the output information to produce individual current control signals for each luminent device; and

adjusting an operating current applied to each luminent device through a single inverter in accord with the current control signals.

2. The method of claim 1 wherein the luminent devices are cold cathode fluorescent lamps.

3. The method of claim 1 wherein the inverter is replaced with a driver and the luminent devices are light emitting diodes.

4. An apparatus for current control of multiple luminent devices comprising:

sensors for sensing individual output information for each luminent device of a multiple device array;

a microcontroller for processing the output information to produce individual current control signals for each luminent device; and

a current control circuit and server control system software for adjusting an individual operating current applied to each luminent device through a single inverter in accord with the individual current control signals.

5. The apparatus of claim 4 wherein the sensors are current sensors.

6. The apparatus of claim 4 wherein the sensors are light sensors.

7. The apparatus of claim 4 wherein the luminent devices are cold cathode fluorescent lamps.

8. The apparatus of claim 4 wherein the inverter is replaced with a driver and the luminent devices are light emitting diodes.

9. A method for modifying the intensity of illumination in multiple luminent devices comprising:

receiving a current control signal from a microcontroller;

isolating a voltage control signal from the current control signal;

filtering the voltage control signal to produce an isolated voltage control signal compatible with a transistor;

setting impedance at the base of a transistor;

operating the transistor in accord with a current response required by the luminent device;

applying the voltage control signal to the transistor to generate an alternating current specified by the current control signal; and

,

routing both polarities of the alternating current to the luminent device.

10. The method of claim 9 wherein the transistor operates in linear mode.

11. The method of claim 9 wherein the transistor operates in switched mode.

12. The method of claim 9 wherein the luminent devices are cold cathode fluorescent lamps.

13. A circuit for modifying the intensity of illumination in a luminent device comprising:

an isolator for receiving a current control signal from a microcontroller and isolating a voltage control signal from the current control signal;

a capacitor for filtering the voltage control signal to produce an isolated voltage control signal compatible with a transistor;

a resistor for setting impedance at the base of the transistor;

a transistor for generating an alternating current, specified by the current control signal, from the voltage control signal; and

,

a diode bridge for routing both polarities of the alternating current to the luminent device.

14. The circuit of claim 13 wherein the isolator is an optical isolator.

15. The circuit of claim 13 wherein the isolator is a photovoltaic converter that converts the current control signal to a proportional light output that is then converted to a voltage.

16. A method for modifying the intensity of illumination in a luminent devices comprising:

sensing individual output information for an individual luminent device in a multiple device array;

processing the output information to produce an individual current control signal for the luminent device;

applying the current control signal to a plurality of switches coupled to parallel capacitors to create an operating current specified by the current control signal; and

,

driving the luminent device with the operating current.

17. The method of claim 16 wherein the luminent device is a cold cathode fluorescent lamp.

18. The method of claim 16 wherein the luminent device is a light emitting diode.

19. A circuit for modifying the intensity of illumination in a luminent devices comprising:

sensors for sensing individual output information for an individual luminent device in a multiple device array;

a microcontroller for processing the output information to produce an individual current control signal for the luminent device;

switches coupled to parallel capacitors for creating an operating current specified by the current control signal; and

,

a luminent device to be driven by the operating current.

20. The circuit of claim 19 wherein the luminent device is a cold cathode fluorescent lamp.

21. The circuit of claim 19 wherein the luminent device is a light emitting diode.