In-Cell Touch Display Power Circuit Stabilizes Voltage
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Solution Overview
Problem
In in-cell touch panel configurations, the integration of touch detection and display drive functions using common electrodes leads to charge discharge issues, causing potential fluctuations and luminance flicker due to the interlayer capacitors' discharge through resistors, which affects the display quality during transitions between touch detection and display periods.
Innovation Solution
A display device is designed to operate in a time division manner, with separate scanning and signal lines set to high impedance during touch detection periods, and a power circuit that supplies alternating current to the drive electrode, including a potential supply period to maintain stable voltage levels, thereby preventing charge discharge and potential fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scanning lines and signal lines are set to high impedance in the touch detection period, then touch detection can be performed, but electric charge stored in interlayer capacitors is discharged through interlayer resistors causing potential fluctuations and luminance flicker
Solution Approach 1:
The patent applies preliminary action by supplying a potential to the scanning line before the touch detection period begins. Specifically, a potential supply unit supplies a potential to the scanning line in a period before the touch detection period, which prevents charge discharge and potential fluctuations during the subsequent touch detection period, thereby eliminating luminance flicker while maintaining touch detection accuracy.
2Device complexity
If common electrodes are used for both display drive and touch detection in time division manner, then device complexity is reduced, but charge stored in pixel capacitors is discharged affecting display quality
Solution Approach 1:
The patent applies dynamics by dynamically controlling the impedance state of the scanning line. The scanning line is set to high impedance during the touch detection period to enable accurate touch detection, and then a potential is supplied in the period before the next display period to restore proper voltage levels. This dynamic impedance control allows the system to switch between touch detection and display modes while maintaining display quality and preventing charge discharge issues.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration stabilizes the voltage supply, reduces luminance flicker, and maintains display quality by preventing charge discharge and potential fluctuations, ensuring consistent performance during both display and touch detection periods.
Implementation Method 1
a power circuit configured to generate a first potential as a reference potential for a high potential of each scanning signal and a second potential as a reference potential for a low potential of each scanning signal
Data Source
AI summary
A display device is configured to alternately execute an operation in a display period and an operation in a detection period in a time division manner. The display device includes: scanning lines; signal lines; a drive electrode; a scanning-line drive circuit; a signal-line drive circuit; a drive-electrode drive circuit configured to supply an alternating-current drive signal to the drive electrode in the detection period; a power circuit configured to generate a first potential for a high potential of each scanning signal and a second potential for a low potential of each scanning signal; a first-potential supply line; and a second-potential supply line. A potential supply period is included in a low-potential period of the drive signal, the potential supply period being a period in which the first potential is supplied to the first-potential supply line and the second potential is supplied to the second-potential supply line.