Liquid Crystal Display Driving Method Using Intermediate Voltage
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Solution Overview
Problem
The FRC driving method for liquid crystal display devices faces challenges in displaying desired halftone gray scales due to differing response speeds between liquid crystal ON and OFF states, making it difficult to achieve accurate halftone gray scale representation.
Innovation Solution
A liquid crystal display device with pixels having a memory function, employing a driving method that sets plural frames as one cycle and temporarily changes gray scales, uses a pixel drive unit to supply an intermediate voltage between high and low voltage sides of a common voltage during transitions from same-phase to reverse-phase voltage supply, reducing the response speed difference between liquid crystal ON and OFF states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If FRC driving method is used to increase the number of gray scales, then the number of displayable gray scales is improved, but the response speed difference between liquid crystal ON and OFF states causes inaccurate halftone gray scale display
Solution Approach 1:
An intermediate voltage signal is introduced as a mediator between the high voltage and low voltage signals during transitions. This intermediate voltage acts as a buffer that equalizes the response characteristics of liquid crystal in both ON and OFF states, eliminating the response speed difference that normally causes halftone gray scale display inaccuracies while maintaining the FRC driving method's ability to display multiple gray scales.
2Adaptability or versatility
If plural frames are set as one cycle for FRC driving, then halftone gray scales can be obtained, but response speed asymmetry between liquid crystal states prevents desired halftone gray scale representation
Solution Approach 1:
The intermediate voltage signal is applied in advance during voltage transitions to counteract the inherent response speed asymmetry of liquid crystal. By introducing this compensating voltage before the main switching occurs, the system pre-corrects for the expected response delay difference, ensuring accurate halftone gray scale representation throughout the FRC driving cycle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the display of desirable halftone gray scales by reducing the response speed difference between liquid crystal ON and OFF states, thereby improving the representation of halftone gray scales during FRC driving.
Implementation Method 1
response speed at transition from white (liquid crystal OFF) to black (liquid crystal ON) is different from response speed at transition from black to white in normally white liquid crystal under the characteristics of liquid crystal in a liquid crystal display device
Data Source
AI summary
A liquid crystal display device in which pixels having a memory function are arranged includes: a display drive unit performing display driving by a driving method for obtaining halftone gray scales by setting plural frames as one cycle and temporarily changing gray scales of respective pixels within one cycle; and a pixel drive unit supplying a voltage having the same phase as, or the reverse phase to, a common voltage the polarity of which is inverted in a given cycle and applied to counter electrodes of liquid crystal capacitors to pixel electrodes of the liquid crystal capacitors. The pixel drive unit supplies an intermediate voltage between high- and low-voltage sides of the common voltage to the pixel electrodes of the liquid crystal capacitors at the time of transition from the supply of the voltage having the same phase to the supply of the voltage having reverse phase.