Brightness control system and method

1 . A television comprising:

a lamp;

video processing circuitry comprising a pattern generator for generating a pattern that is added to an overscan portion of a television picture signal;

a detector positioned in the overscan region of the television picture for detecting the added pattern and providing detection signals based on the detecting; and

a controller for controlling brightness of the lamp based on the detection signals.

2 . The television according to claim 1 , wherein the pattern is added to the television picture signal at all times.

3 . The television according to claim 1 , wherein the pattern is selectively added to the television picture signal.

4 . The television according to claim 3 , wherein the pattern is added to the television picture signal during a channel change.

5 . The television according to claim 3 , wherein the pattern is added to the television picture signal during a volume change.

6 . The television according to claim 3 , wherein the pattern is added to the television picture signal in response to a user input.

7 . The television according to claim 3 , wherein the pattern is added to the television picture signal at periodic real time intervals.

8 . The television according to claim 3 , wherein the pattern is added to the television picture signal at periodic operating time intervals.

9 . The television according to claim 3 , wherein the pattern is added to the television picture signal in response to a television power down signal.

10 . The television according to claim 1 , wherein the pattern is a sold color.

11 . The television according to claim 1 , wherein the pattern is a grid of different colors.

12 . The television according to claim 1 , wherein the pattern is sized to cover the detector.

13 . The television according to claim 1 , wherein the controller controls the brightness of the lamp to maintain a specified picture brightness.

14 . The television according to claim 1 , wherein the controller implements an algorithm to determine how much to change the brightness of the lamp based on the detection signals.

15 . The television according to claim 1 , wherein the controller uses a look-up table to determine how much to change the brightness of the lamp based on the detection signals.

16 . The television according to claim 1 , wherein the controller applies hysteresis to the controlling of the brightness of the lamp based on the detection signals.

17 . The television according to claim 1 , further comprising:

a memory for storing a record of brightness of the lamp over time.

18 . The television according to claim 1 , wherein the memory stores records of brightness over time for multiple lamps.

19 . An automatic brightness adjustment system comprising:

a light sensor positioned in the overscan portion of a television display;

a control circuit for comparing a brightness sensed by the light sensor to a reference brightness and automatically adjusting the brightness of a lamp in response thereto.

20 . The system according to claim 19 , further comprising:

a memory for storing data indicative of the reference brightness.

21 . The system according to claim 19 , wherein the comparing is performed in response to a channel change.

22 . The system according to claim 19 , wherein the comparing is performed in response to a volume change.

23 . The system according to claim 19 , wherein the comparing is performed at periodic intervals.

24 . A television incorporating the automatic brightness adjustment system of claim 19 .

25 . A method of adjusting brightness comprising:

sensing a brightness in the overscan portion of a television display;

comparing the sensed brightness to a reference brightness; and

adjusting the brightness of a lamp in response to the comparing.

26 . A storage medium readable by a processing system and storing therein a computer program for adjusting a brightness by comparing a brightness sensed by a light sensor disposed in an overscan portion of a television display and adjusting the brightness of a lamp in response to the comparing.

27 . A television comprising a storage medium according to claim 26 .

28 . A television comprising:

a lamp;

a memory storing characteristic data indicative of brightness changes over time for the lamp; and

a controller for controlling brightness of the lamp over time based on the characteristic data.

29 . The television according to claim 28 , wherein the characteristic data comprises a look-up table of lamp operating times and corresponding lamp brightness values.

30 . The television according to claim 28 , wherein the characteristic data comprises a function relating lamp operating time and lamp brightness.