Automatic contrast control for liquid crystal displays
First Claim
Patent Images
1. An LCD (liquid crystal display ) comprising:
- a main display area having a first adjustable operating voltage;
at least one test pixel having a second adjustable operating voltage;
for each test pixel, a light sensor located to make luminance measurements on the test pixel, and a reference light source located to transmit light through the test pixel to the light sensor; and
processing means for controlling the second operating voltage to be a plurality of different values over a range, for collecting luminance measurements from said light sensor(s) for ON, OFF, and disable pixel states for each of said different values in said range, and for setting the first operating voltage on the basis of luminance measurements.
9 Assignments
0 Petitions
Accused Products
Abstract
An LCD with automatic contrast control is provided. A light sensor is mounted over a test pixel which is separate form the main viewing area of the LCD for taking luminance measurements for "ON", "OFF", and "surround" pixel states for a series of candidate operating voltages. The pixel contrast ratio and background contrast ratio are computed for each candidate voltage and the voltage resulting in the best contrast is selected as the operating voltage for the entire LCD.
191 Citations
28 Claims
-
1. An LCD (liquid crystal display ) comprising:
-
a main display area having a first adjustable operating voltage; at least one test pixel having a second adjustable operating voltage; for each test pixel, a light sensor located to make luminance measurements on the test pixel, and a reference light source located to transmit light through the test pixel to the light sensor; and processing means for controlling the second operating voltage to be a plurality of different values over a range, for collecting luminance measurements from said light sensor(s) for ON, OFF, and disable pixel states for each of said different values in said range, and for setting the first operating voltage on the basis of luminance measurements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. An LCD (liquid crystal display) comprising:
-
a main display area having a adjustable operating voltage; a test pixel having a second adjustable operating voltage; a light sensor located to make luminance measurements on the test pixel, and a reference light source located to transmit light through the test pixel to the light sensor; and processing means for setting the second operating voltage to a sequence of values and collecting luminance measurements from the light sensor for each of these values, wherein the luminance measurements comprise measurements for each of three states of the test pixel, these being ON, OFF, and disable, for determining a pixel contrast ration and a background contrast ration for each of these values and for which value the contrast performance is best, the pixel contrast ration being the ratio of the ON luminance measurement to the OFF luminance measurement, and the background contrast ration being the ratio of the OFF luminance to the disable, and for setting the first operating voltage to the value having the best contrast performance. - View Dependent Claims (15, 16, 17, 18, 19)
-
-
20. An LCD (liquid crystal display) comprising:
-
a main display area having a first adjustable operating voltage; three test pixels having a second adjustable operating voltage, one pixel being permanently in a disable state, one being in an ON state and one being in an OFF state; three light sensors, one for each test pixel located to make luminance measurements on the respective test pixel, a reference light source located to transmit light through the test pixels to the light sensors; processing means for setting the second operating voltage to a sequence of values and collecting luminance measurements from the light sensors for each of these values, wherein the luminance measurements comprise an ON luminance measurement for the pixel permanently ON, an OFF luminance measurement for the pixel permanently OFF and a disable luminance measurement for the pixel permanently disabled, for determining a pixel contrast ratio and a background contrast ratio for each of these values and for which value the contrast performance is best, the pixel contrast ration being the ratio of the ON luminance measurement to the OFF luminance measurement, and the background contrast ration being the ratio of the OFF luminance to the disable, and for setting the first operating voltage to the value having the best contrast performance. - View Dependent Claims (21, 22, 23, 24)
-
-
25. An LCD (liquid crystal display) comprising:
-
a main display area and at least one test pixel having an adjustable operating voltage; for each test pixel, a light sensor located to make luminance measurements on the test pixel, and a reference light source located to transmit light through the test pixel to the light sensor; and processing means for controlling the operating voltage to be a plurality of different values over a range, for collecting luminance measurements from said light sensor(s) for ON, OFF, and disable pixel states for each of said different values in said range, and for setting the operating voltage on the basis of luminance measurements. - View Dependent Claims (26, 27, 28)
-
Specification