Liquid Crystal Display Driver Partial Update Masking
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Solution Overview
Problem
Active-matrix display devices face power consumption increases with higher resolution demands, and partial display techniques lead to image distortion when switching image data with changes in the partial-display area, especially due to time differences in data transfer and area setting.
Innovation Solution
A drive circuit and method that utilize a register to control a switch for selecting a background pattern during partial-display area changes, using an address counter to estimate the timing of writing to the partial memory and masking the transfer period of partial-display data to prevent image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If partial display technique is used to reduce power consumption, then power consumption is reduced, but image distortion occurs during partial-display area updates
Solution Approach 1:
The patent applies preliminary action by updating the partial-display area setting before the partial-display data transfer completes. The system prepares the area configuration in advance, and uses a mask to temporarily hide the transition period, ensuring that the updated area setting is ready before data transfer finishes, thus preventing image distortion while maintaining power savings
Solution Approach 2:
The patent introduces a mask as an intermediary element that temporarily covers the display during the transition period when area settings are updated. This mask acts as a mediator between the area setting update and data transfer, preventing the display of distorted images during the transition while allowing both operations to proceed without interference
2Speed
If partial-display area setting is updated before data transfer, then update timing is improved, but time difference between setting and data causes display distortion
Solution Approach 1:
The system performs preliminary action by updating the partial-display area setting before the data transfer completes. This ensures that the area configuration is prepared in advance, and the mask temporarily hides the transition period, allowing the setting update to occur at optimal timing without causing synchronization issues
Solution Approach 2:
The mask serves as an intermediary that bridges the timing difference between area setting updates and data transfer completion. It temporarily covers the display during the transition, allowing the setting update to proceed at high speed while preventing synchronization errors from manifesting as visible distortion
3Reliability
If mask is used to prevent image distortion during area updates, then image quality is maintained, but device complexity increases
Solution Approach 1:
The mask circuit is designed with multi-functionality, serving both to prevent image distortion during area updates and to maintain normal display operation. By making the mask control circuit universal and integrating it into the existing display driver architecture, the patent minimizes additional complexity while achieving reliable image quality protection
Data Source
AI summary
In a liquid crystal driver of a liquid crystal display having a structure to switch between image data for partial display from a partial memory and non-display (background pattern), changes in a partial-display area are detected according to a setting command of the partial-display area, and a mask switch is controlled so as to select the background pattern. Timing to write to the last line of the changed partial-display area in the partial memory is determined by an address counter for controlling the partial memory, and the mask switch is controlled so as to select the image data of the partial memory from a next frame.