Voltage Selection Circuit for Display Grayscale Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display driving operations using a combination of high-driving performance first output circuits with dead zones and highly accurate second output circuits without dead zones often result in brightness differences among display units, degrading display quality due to variations in output voltages caused by differing transistor lengths.
Innovation Solution
A method involving a voltage selection circuit, a first output circuit, and a second output circuit, where the control circuit alternates between driving both circuits during a first period and bringing the second output circuit into an OFF state during a second period, allowing the first output circuit to output the final voltage without being affected by the second output's variations, thereby reducing voltage variations and brightness differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-driving performance first output circuit with dead zone and a highly accurate second output circuit without dead zone are used together, then the power consumption is reduced and the grayscale voltage can be output with high accuracy, but brightness differences appear among display units due to variations in output voltages caused by different transistor lengths
Solution Approach 1:
The control circuit determines in advance whether the second output circuit should be in the ON state or OFF state based on the grayscale voltage to be output. When the grayscale voltage is within a specific range (near the dead zone of the first output circuit), the control circuit sets the second output circuit to OFF state beforehand, preventing voltage variation from affecting the final output accuracy.
Solution Approach 2:
The control circuit acts as an intermediary that coordinates between the first and second output circuits. It selectively controls the second output circuit's state to mediate the interaction between the two circuits, ensuring that the high-accuracy second circuit does not interfere with the final voltage output when its precision would otherwise cause display non-uniformity.
2Measurement precision
If the second output circuit is always kept in ON state to provide high accuracy, then voltage accuracy is improved, but power consumption increases and the first output circuit cannot function independently
Solution Approach 1:
The control circuit periodically switches the second output circuit between ON and OFF states based on the required grayscale voltage. Instead of keeping the second circuit continuously ON, it activates the second circuit only when necessary (when high precision is needed) and keeps it OFF otherwise, reducing power consumption while maintaining accuracy when required.
Solution Approach 2:
The control circuit dynamically adjusts the state of the second output circuit based on real-time requirements. The second circuit transitions between ON and OFF states depending on the grayscale voltage being output, allowing the system to adapt power consumption to actual performance needs rather than operating in a fixed state.
3Device complexity
If the first output circuit is used alone for all grayscale voltages, then device complexity is reduced, but the power consumption increases and high accuracy cannot be achieved for all voltages
Solution Approach 1:
The output circuit is segmented into two specialized circuits: the first output circuit handles grayscale voltages outside the specific range (where it operates efficiently), and the second output circuit handles grayscale voltages within the specific range (where high accuracy is needed). This segmentation allows each circuit to operate in its optimal performance region, reducing overall power consumption.
Solution Approach 2:
Different parts of the grayscale voltage range are handled by different circuits with different characteristics. The first output circuit (with dead zone) is used for voltage ranges where speed is prioritized, while the second output circuit (without dead zone) is used for voltage ranges where precision is prioritized. This local optimization reduces power consumption by using the most efficient circuit for each specific voltage range.
Data Source
AI summary
An electro-optic device includes a voltage selection circuit configured to select a higher electric potential side voltage and a lower electric potential side voltage that correspond to upper bits of data, a first output circuit configured to output a first output voltage corresponding to lower bits of data to a data line, a second output circuit having a driving capability higher than that of the first output circuit and configured to output a second output voltage corresponding to upper bits of data among the lower bits of data to the data line, and a control circuit configured to allow the first output circuit and the second output circuit to be driven during a first period, and configured to bring an output of the second output circuit into an OFF state or an almost OFF state during a second period.