Pixel Driving Circuit Offset Voltage Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display devices suffer from poor uniformity in display brightness due to offset voltages in pixel driving circuits, affecting the consistency of light-emitting units.
Innovation Solution
A pixel driving circuit is designed with a time length controlling module, current controlling module, and outputting module, which includes a comparator, energy storage elements, and offset voltage writing sub-circuits to eliminate the influence of offset voltages by writing the offset voltage into energy storage elements, allowing the comparator to output a comparison signal for controlling the current of light-emitting units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If offset voltage exists in the comparator, then the comparator can perform voltage comparison, but the display brightness uniformity deteriorates
Solution Approach 1:
The patent converts the harmful offset voltage into a beneficial parameter by storing it in the energy storage element. The offset voltage writing sub-circuit captures the offset voltage and stores it in the energy storage element, allowing the comparator to compensate for the offset voltage effect. This transforms the harmful offset voltage into a stored value that can be used for compensation, thereby improving brightness uniformity.
Solution Approach 2:
The patent performs preliminary action by writing the offset voltage into the energy storage element before the normal operation. The offset voltage writing sub-circuit operates in advance to capture and store the offset voltage, so that when the comparator performs voltage comparison during normal operation, the offset voltage has already been accounted for through the stored value, preventing brightness uniformity deterioration.
2Reliability
If the offset voltage writing sub-circuit is added, then the brightness uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by making the energy storage element serve multiple purposes. The energy storage element both stores the offset voltage for compensation and participates in the voltage comparison function of the comparator. Additionally, the switching elements are configured to perform both offset voltage writing and normal operation functions, reducing the need for separate dedicated components and thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the offset voltage writing function with the existing comparator structure. The offset voltage writing sub-circuit integrates with the comparator and energy storage element, combining the offset compensation function with the voltage comparison function. This merging approach avoids adding completely separate independent circuits, thereby improving brightness uniformity while minimizing the increase in device complexity.
Data Source
AI summary
A pixel driving circuit includes a current controlling module, an outputting module and a time length controlling module including a comparator, a first energy storage element, an offset voltage writing sub-circuit, and first and second output sub-circuits. First terminal of first energy storage element is connected with first input terminal of comparator and second terminal with the first output sub-circuit. The second output sub-circuit is connected with second input terminal of comparator. The offset voltage writing sub-circuit writes an offset voltage of comparator to the first energy storage element. One of the first and second output sub-circuits outputs time signal and the other outputs reference voltage signal. The comparator outputs comparison signal according to the time signal and the reference voltage signal. The current controlling module outputs current signal. The outputting module turns on responsive to the comparison signal and controls current of light-emitting unit according to the current signal.