Touch Screen Panel Synchronized Clock and Touch Driving Signals
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Solution Overview
Problem
Conventional touch screen panels using the electrostatic capacitance method are affected by power noise due to asynchronous driving of the charge pump circuit, leading to touch errors, especially as panels increase in size and require high voltage for improved signal-to-noise ratio.
Innovation Solution
Synchronizing the clock signal and touch driving signals with each other, using a clock signal generator and touch driver to set reference timings, and employing a touch controller to detect touch positions by averaging touch sensing signals while excluding noise-influenced data, thereby reducing the impact of power noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the charge pump circuit and touch driver are driven asynchronously, then the device can operate with simpler timing control, but power noise is generated aperiodically causing touch errors
Solution Approach 1:
The patent applies periodic action by synchronizing the charge pump circuit and touch driver to operate at the same periodic frequency. The clock signal generator produces a clock signal that drives both the charge pump circuit and the touch driver, ensuring that voltage pumping operations and touch sensing operations occur in a periodic, synchronized manner. This eliminates aperiodic power noise while maintaining operational simplicity through unified clock-driven timing control.
2Measurement precision
If the touch driver is driven at high voltage to improve signal-to-noise ratio, then touch detection sensitivity increases, but the influence of power noise increases
Solution Approach 1:
The patent converts the harmful aperiodic power noise into beneficial periodic noise through synchronization. By driving the charge pump circuit and touch driver at the same frequency, the power noise becomes periodic and predictable. The touch controller then uses synchronization information to identify and exclude noise-influenced sensing signals, transforming the previously harmful aperiodic interference into a manageable periodic signal that can be systematically filtered out.
Solution Approach 2:
The patent implements feedback by using the clock signal as a reference for both driving the charge pump circuit and controlling the touch driver. The touch controller receives synchronization information from the clock signal generator and uses this feedback to determine which touch sensing signals are influenced by power noise. This feedback mechanism enables the system to adjust its signal processing to exclude noise-contaminated data, maintaining high detection sensitivity while mitigating noise impact.
3Speed
If the clock signal frequency is increased to improve touch response speed, then touch detection speed increases, but power noise frequency increases making it harder to filter
Solution Approach 1:
The patent introduces the clock signal as an intermediary that mediates between the charge pump circuit and the touch driver. This clock signal serves as a common reference that coordinates both operations at the same frequency. The touch controller uses this intermediary clock signal to identify noise patterns and exclude affected sensing signals. This intermediary approach enables high-speed operation while simplifying noise filtering, as the clock signal provides a clear reference for identifying and removing noise-contaminated data without requiring complex filtering algorithms.
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 synchronization of clock and touch driving signals ensures periodicity and reduces power noise influence, allowing accurate touch position detection and minimizing errors in large touch screen panels.
Implementation Method 1
a charge pump circuit configured to generate an output voltage based on an input voltage and at least one clock signal
Implementation Method 2
senses changes in capacitance formed in the sensing electrodes when a user's finger or stylus pen comes in contact with the sensing electrodes, thereby detecting a touch position
Data Source
AI summary
A touch screen panel includes a plurality of sensing electrodes arranged in a touch active area, a charge pump circuit for generating an output voltage based on an input voltage and at least one clock signal, a clock signal generator for generating the clock signal, and a touch driver for generating touch driving signals by using the output voltage and applying the touch driving signals to the sensing electrodes. In the touch screen panel, the clock signal and the touch driving signals are synchronized with each other.