Double-Bank Display Driver Chopping for Offset Cancellation
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Solution Overview
Problem
The double bank structure in organic light emitting display apparatuses experiences output voltage deviations between upper and lower output buffers, leading to overcurrent and increased power consumption due to opposite offset directions of the output voltages.
Innovation Solution
Implementing a display apparatus with a first and second data driving portion where each output buffer alternates between positive and negative chopping states by frame, ensuring the offset directions of output voltages from both buffers are the same, thereby reducing voltage deviation and overcurrent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the upper and lower output buffers output voltages with opposite offset directions in a double bank structure, then the data driving structure can be simplified, but output voltage deviation occurs leading to overcurrent and increased power consumption
Solution Approach 1:
The patent applies periodic action by alternating the chopping states of upper and lower output buffers between frames. In odd frames, the upper output buffer operates in a positive chopping state while the lower operates in a negative chopping state. In even frames, their states are reversed. This periodic alternation ensures that offset deviations occur in opposite directions at different times, causing them to cancel out over time, thereby preventing sustained overcurrent and reducing power consumption while maintaining the simplified double bank structure.
2Productivity
If the upper and lower output buffers operate with opposite offset directions, then the double bank structure can drive data lines efficiently, but voltage deviation causes overcurrent that damages driving circuits
Solution Approach 1:
The patent implements periodic alternation of chopping states between upper and lower output buffers across frames. This periodic action maintains the efficient double bank driving capability while ensuring that voltage offsets alternate in direction, preventing sustained overcurrent conditions that would damage circuits. The alternation pattern preserves productivity while protecting reliability.
Solution Approach 2:
The patent converts the potentially harmful opposite offset directions into a beneficial cancellation effect. By timing the alternation of chopping states appropriately, the voltage deviations that would normally cause overcurrent are instead made to oppose each other at different times, causing the deviations to cancel out over the course of multiple frames. This transforms a harmful effect into a beneficial self-correcting mechanism.
Data Source
AI summary
A display apparatus includes: a display panel including a plurality of data lines and a plurality of pixels respectively connected to the plurality of data lines; a first data driving portion including a plurality of channels respectively connected to one ends of the plurality of data lines and a plurality of first output buffers which are respectively arranged at the plurality of channels; and a second data driving portion including a plurality of channels respectively connected to the other ends of the plurality of data lines and a plurality of second output buffers which are respectively arranged at the plurality of channels, wherein each of the first and second output buffers is alternately in a positive (+) chopping state and a negative (−) chopping state by frame, and wherein offset directions of output voltages of the first and second output buffers at the corresponding channel are the same in the same frame.