Gate Driving Circuit Leakage Blocking for Touch Display Stability
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Solution Overview
Problem
In touch screen-integrated display devices, leakage currents from the Q node and QB node during the touch driving period can cause voltage drops, leading to abnormal signal outputs and poor image quality, such as the 'Dim' phenomenon where horizontal lines appear on the display panel.
Innovation Solution
A gate driving circuit with Q node and QB node stabilizers is implemented, which includes a first node stabilizer to block leakage current paths during the touch driving period by turning off the power supply voltage and a second node stabilizer to maintain the QB node in a stable floating state, using auxiliary transistors connected to the power supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gate driving circuit operates during the touch driving period, then the touch function can be performed, but leakage currents from Q node and QB node cause voltage drops and image quality degradation
Solution Approach 1:
The gate driving circuit is divided into multiple independent stages, each with its own leakage current blocking circuit. This segmentation allows each stage to independently manage its leakage current, preventing cumulative voltage drops that would degrade image quality while maintaining touch functionality across the display.
Solution Approach 2:
A leakage current blocking circuit is introduced as an intermediary component between the Q node/QB node and the output. This blocking circuit, comprising switching elements and capacitors, selectively blocks leakage current paths during the touch driving period while allowing normal signal transmission, thus resolving the conflict between touch operation and image quality.
2Reliability
If the power supply voltage is continuously supplied to maintain stable operation, then the circuit reliability is improved, but leakage currents increase during the touch driving period
Solution Approach 1:
The power supply voltage to each stage is dynamically controlled based on the operating mode. During the touch driving period, the leakage current blocking circuit is activated to block leakage paths, while during the display driving period, normal power supply is maintained. This dynamic adjustment reduces energy loss from leakage currents while maintaining circuit reliability when needed.
Solution Approach 2:
The blocking switching elements are turned off during the display driving period to discard the blocking function, allowing normal circuit operation. During the touch driving period, these same elements are activated to recover and block leakage current paths. This periodic discarding and recovering of the blocking function optimizes both energy efficiency and circuit reliability.
Data Source
AI summary
A gate driving circuit includes a plurality of stages sequentially connected to one another. The plurality of stages each includes an output unit for outputting a first clock signal as a gate output voltage in response to a voltage of a Q node and a voltage of a QB node; a first node controller configured to charge the voltage of the Q node in response to the gate output voltage from a previous stage; a second node controller configured to charge the voltage of the QB node in response to a second clock signal having a different phase from the first clock signal; a first node stabilizer configured to block a leakage current path of the Q node when the second clock signal is not applied; and a second node stabilizer configured to block a leakage current path of the QB node when the second clock signal is not applied.