Bypass Capacitor Pre-Charging for Display Touch Settling
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Solution Overview
Problem
Existing display panels face challenges in efficiently switching between display and touch periods at high frequencies, leading to suboptimal performance in detecting touch inputs and displaying image data due to limitations in current output and settling time.
Innovation Solution
The display panel is pre-charged using a two-stage process involving a display voltage and a touch voltage, with a bypass capacitor limiting current output and controlling the settling time, allowing for rapid transitions between display and touch periods by initially charging via the bypass capacitor and then completing the charge through a touch voltage source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the display panel switches between display period and touch period more frequently to enhance touch detection ability, then the touch detection performance is improved, but the current output requirements increase and settling time becomes insufficient
Solution Approach 1:
The bypass capacitor is pre-charged to the touch voltage level during the display period before the touch period begins. This preliminary charging action ensures that when the touch period starts, the capacitor is already at the required voltage level, enabling immediate touch detection without requiring additional current output from the voltage source during the touch period.
Solution Approach 2:
The bypass capacitor serves as an intermediary energy storage element between the voltage source and the display panel. It mediates the voltage transfer by storing energy during the display period and releasing it during the touch period, thereby decoupling the current output requirements from the switching frequency and reducing the burden on the voltage source.
2Measurement precision
If the display panel switches between display period and touch period more frequently to enhance touch detection ability, then the touch detection performance is improved, but the settling time becomes insufficient
Solution Approach 1:
The bypass capacitor is pre-charged to the touch voltage level during the display period before the touch period begins. This preliminary charging action ensures that when the touch period starts, the capacitor is already at the required voltage level, enabling immediate touch detection without requiring additional current output from the voltage source during the touch period.
Solution Approach 2:
The bypass capacitor serves as an intermediary energy storage element between the voltage source and the display panel. It mediates the voltage transfer by storing energy during the display period and releasing it during the touch period, thereby decoupling the current output requirements from the switching frequency and reducing the burden on the voltage source.
3Device complexity
If a single voltage source is used to charge the display panel during both display and touch periods, then the device complexity is reduced, but the ability to effectively display image data and receive touch inputs simultaneously deteriorates
Solution Approach 1:
The system dynamically switches the connection configuration of the bypass capacitor between two states: during the display period, the capacitor is connected to the voltage source to charge to the touch voltage level; during the touch period, the capacitor is connected to the display panel to discharge and maintain the touch voltage. This dynamic reconfiguration enables a single capacitor to serve multiple functions without requiring separate voltage sources.
Solution Approach 2:
The bypass capacitor performs multiple functions: it acts as a voltage storage element during the display period and as a voltage supply element during the touch period. This multi-functionality allows the system to maintain both display and touch capabilities using a simplified voltage source configuration, where the same capacitor adapts its role based on the operational period.
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 approach enables the display panel to alternate between display and touch periods more frequently, improving touch detection and image quality by limiting current and reducing settling time, thereby enhancing the overall performance of the electronic device.
Implementation Method 1
a bypass capacitor (Cb) that may limit the amount of current provided to the display panel and control the amount of time for the voltage in the display panel to settle to the touch voltage (VCOM_T)
Data Source
AI summary
A method for pre-charging a display panel may include simultaneously charging the display panel that displays image data and receives one or more touch inputs via a first voltage source and a capacitor that provides a first voltage to the display panel via a second voltage source. The first voltage is associated with receiving the one or more touch inputs, and the display panel and the capacitor are simultaneously charged for a first amount of time. The method may then include charging the display panel via the capacitor after the first amount of time for a second amount of time and charging the display panel via the second voltage source after the second amount of time for a third amount of time.