Scan Driver Circuit for Display Mobility Sensing
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Solution Overview
Problem
Existing scan drivers for display devices face challenges in accurately sensing characteristics of display elements, such as mobility and deterioration, within a short time frame, particularly during the porch period, and suffer from voltage stress on transistors.
Innovation Solution
The implementation of a scan driver with multiple scan signal output circuits connected through scan lines, including drive and buffer circuits, which apply drive signals, connection signals, and clock signals to select scan lines for mobility sensing, reducing voltage stress by using capacitors and transistors to manage signal voltages effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing operations are performed during the display period, then sensing time is sufficient, but display quality deteriorates due to interruption of normal display operation
Solution Approach 1:
The frame period is segmented into display period and porch period, with sensing operations performed during the porch period when display operation is not active. This temporal segmentation allows sensing to occur without interrupting display quality while still utilizing the available time window for accurate measurements.
Solution Approach 2:
Sensing operations are performed in advance during the porch period before the next display frame begins. By completing sensing measurements beforehand, the system prepares the necessary sensing data without affecting the upcoming display operation, ensuring both display quality and sensing accuracy are maintained.
2Productivity
If sensing operations are performed during the porch period, then display quality is maintained, but sensing time is insufficient for accurate measurements
Solution Approach 1:
The scan driver circuit continuously outputs scan signals during both display and porch periods without interruption. By maintaining continuous scan signal output, the system ensures that sensing operations during the porch period have sufficient time to complete accurate measurements while keeping the display system ready for the next frame.
Solution Approach 2:
The scan driver circuit dynamically adjusts its operation by outputting scan signals during both display and porch periods, adapting the timing and duration of scan signal output to accommodate both display requirements and sensing needs. This dynamic operation allows the system to optimize sensing time within the constrained porch period while maintaining display quality.
3Measurement precision
If high voltage is applied to ensure accurate sensing, then sensing signal strength is sufficient, but voltage stress on transistors increases
Solution Approach 1:
The buffer circuit is strategically positioned to provide localized voltage boosting only at the scan signal output node where it is needed for sensing operations. This local quality enhancement allows sufficient sensing signal strength to be achieved without subjecting the entire transistor chain to high voltage stress, as the voltage amplification is confined to a specific circuit location.
Solution Approach 2:
The buffer circuit acts as an intermediary between the scan driver circuit and the scan lines. It receives the scan signals from the driver and provides the necessary voltage boost to the scan lines, thereby mediating the voltage level to ensure accurate sensing while protecting the upstream transistors from direct high voltage exposure.
4Measurement precision
If multiple scan signal output circuits are used to improve sensing capability, then sensing accuracy is enhanced, but device complexity increases
Solution Approach 1:
The scan driver circuit is designed with multi-functionality, serving both display operations and sensing operations through the same basic circuit structure. The scan signal output circuits can output scan signals for both display purposes and sensing purposes, eliminating the need for separate dedicated sensing circuits and thereby reducing overall device complexity.
Solution Approach 2:
The display operation and sensing operation are merged into a single integrated scan driver circuit. The same scan signal output circuits that drive the display also perform sensing functions, combining multiple functions into one unified system rather than using separate independent circuits for each function.
Data Source
AI summary
A scan driver for a display device includes scan signal output circuits connected to each other through scan lines. Each scan signal output circuit includes: a drive circuit to apply a first drive signal to a first drive node, to apply a second drive signal to a second drive node, and to apply a connection signal to a connection signal output node based on i) an input signal which is one of either a scan start signal or a scan signal applied by another scan signal output circuit, ii) a clock signal, and iii) an on-level voltage; and a buffer circuit to receive the connection signal, the first drive signal, and the second drive signal from the drive circuit, and to output one of scan signals to one of the scan lines based on the first drive signal, the second drive signal, and the clock signal.