Scan Driver Bias Voltage Adjustment for Display Flicker
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Solution Overview
Problem
Display devices experience flicker due to hysteresis characteristics in pixel circuits when the frame rate of the panel driving frame decreases, leading to suboptimal display performance.
Innovation Solution
A scan driver is designed to apply an adjustable bias voltage to specific nodes in the pixel circuit, utilizing a configuration with stages that include inputters, stress relievers, carry signal outputters, output signal outputters, maintainers, and stabilizers to manage clock signals and power supply voltages, allowing for adjustment of the bias voltage by varying the high and low power supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frame rate of the panel driving frame is decreased to enable variable frame rate technology, then power consumption and heat generation are reduced, but hysteresis characteristics in the driving transistor cause flicker on the display panel
Solution Approach 1:
The patent applies parameter changes by adjusting the bias voltage level applied to the gate terminal of the driving transistor. By changing the voltage parameter (applying a higher bias voltage when frame rate is decreased), the hysteresis characteristics of the driving transistor are improved, preventing flicker while enabling variable frame rate operation. This resolves the contradiction by dynamically changing the electrical parameter to maintain display stability across different frame rates.
2Device complexity
If a fixed bias voltage is applied to the gate terminal of the driving transistor, then the circuit structure is simple, but the hysteresis characteristics cannot be improved when frame rate varies
Solution Approach 1:
The patent implements dynamics by making the bias voltage adjustable rather than fixed. The bias voltage generator is configured to change the bias voltage level based on the frame rate of the panel driving frame. This dynamic adjustment allows the circuit to adapt to varying operating conditions, improving hysteresis characteristics when frame rate decreases while maintaining manageable circuit complexity through a controlled adjustment mechanism.
3Adaptability or versatility
If the number of self scan periods is increased to extend the panel driving frame duration, then variable frame rate is achieved, but the hysteresis effect becomes more pronounced causing display flicker
Solution Approach 1:
The patent applies preliminary anti-action by proactively adjusting the bias voltage before hysteresis effects cause visible flicker. When the frame rate is decreased and self-scan periods are extended, the bias voltage generator preemptively increases the bias voltage level to counteract the developing hysteresis characteristics. This preventive measure addresses the harmful flicker effect before it becomes pronounced, enabling versatile variable frame rate operation while maintaining display quality.
Data Source
AI summary
Provided is a scan driver for applying a bias voltage comprising a kth stage that includes an inputter transmitting an input signal to a first node, a stress reliever disposed between the first node and a second node, a carry signal outputter receiving a high-power-supply voltage and a second clock signal and outputting the second clock signal, an output signal outputter receiving the high-power-supply voltage and a third clock signal and outputting the third clock signal, a maintainer transmitting the first clock signal to a third node, and a stabilizer applying a first low-power-supply voltage to the third node and the high-power-supply voltage to the first node. The first and second clock signals selectively toggle between the high-power-supply voltage and the first low-power-supply voltage, the third clock signal selectively toggles between the high-power-supply voltage and a second low-power-supply voltage, and the bias voltage is adjusted as the second low-power-supply voltage varies.