Liquid crystal display system having improved temperature compensation
First Claim
1. A liquid crystal display system comprising:
- a liquid crystal display segment;
a display drive means for alternatively coupling said display segment to first and second voltages;
a capacitance ratio selection means, responsive to the temperature of said display segment, for selecting one of a plurality of predetermined ratio values, each predetermined ratio value corresponding to one of a plurality of temperature ranges; and
a temperature compensation means for determining the ratio of the capacitance of said display segment when coupled to said first voltage to the capacitance of said display segment when coupled to said second voltage, and for changing said second voltage to converge said ratio to said selected predetermined ratio value.
1 Assignment
0 Petitions
Accused Products
Abstract
A liquid crystal display system having improved temperature compensation using multiple capacitance ratios for different display temperature ranges. The capacitance of a liquid crystal display segment is measured when preconditioned to a first voltage below the threshold voltage and when preconditioned to a second voltage above the threshold voltage. Separate embodiments are disclosed which sequentially measure the capacitance of a single segment or which simultaneously measures the capacitance of two segments. The magnitude of the second voltage is adjusted to converge the ratio of the measured capacitances to a predetermined value selected according to the display temperature. The on segment and off segment voltages are then formed based on fixed percentages of this second voltage. In a preferred embodiment the second voltage, the on voltage and the off voltage are formed by duty cycle blanking fixed voltages according to a duty cycle blanking count which is adjusted to achieve the selected capacitance ratio.
-
Citations
20 Claims
-
1. A liquid crystal display system comprising:
-
a liquid crystal display segment; a display drive means for alternatively coupling said display segment to first and second voltages; a capacitance ratio selection means, responsive to the temperature of said display segment, for selecting one of a plurality of predetermined ratio values, each predetermined ratio value corresponding to one of a plurality of temperature ranges; and a temperature compensation means for determining the ratio of the capacitance of said display segment when coupled to said first voltage to the capacitance of said display segment when coupled to said second voltage, and for changing said second voltage to converge said ratio to said selected predetermined ratio value. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A display drive circuit for use in a liquid crystal display system having a liquid crystal display segment, said drive circuit comprising:
-
a display drive means for alternately coupling said display segment to first and second voltages; a capacitance ratio selection means, responsive to the temperature of said display segment, for selecting one of a plurality of predetermined ratio values corresponding to one of a plurality of temperature ranges; and a temperature compensation means for determining the ratio of the capacitance of said display segment when coupled to said first voltage to the capacitance ratio of said display segment when coupled to said second voltage, and for changing said second voltage to converge said ratio to said selected predetermined ratio value. - View Dependent Claims (7, 8, 9, 10)
-
-
11. A liquid crystal display system comprising:
-
a first and second liquid crystal display segments; a display drive means for coupling said first display segment to a first voltage and for coupling said second display segment to a second voltage; a capacitance ratio selection means, responsive to the temperature of said display segments, for selecting one of a plurality of predetermined ratio values, each ratio value corresponding to one of a plurality of temperature ranges; and a temperature compensation means for determining the ratio of the capacitance of said first display segment when coupled to said first voltage to the capacitance of said second display segment when coupled to said second voltage and for changing said second voltage and for changing said second voltage to converge said ratio to said selected predetermined ratio value. - View Dependent Claims (12, 13, 14, 15)
-
-
16. A display drive circuit for use in a liguid crystal display system having first and second display segments, said display drive circuit comprising:
-
a display drive means for coupling said first display segment to a first voltage and for coupling said second display segment to a second voltage; a capacitance ratio selection means, responsive to the temperature of said display segments, for selecting one of a plurality of predetermined ratio values, each ratio value corresponding to one of a plurality of temperature ranges; and a temperature compensation means for determining the ratio of the capacitance of said first display segment when coupled to said first voltage to the capacitance of said second display segment when coupled to said second voltage and for changing said second voltage and for changing said second voltage to converge said ratio to said selected predetermined ratio value. - View Dependent Claims (17, 18, 19, 20)
-
Specification