Touch Panel Voltage Switching for In-Cell Touch Range Limits
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Solution Overview
Problem
Conventional touch panels face limitations in voltage range due to parasitic diode conduction and cross-voltage limitations, particularly in in-cell and touch applications, where the maximum VGH-VGL limit is restricted, affecting the operational range of gate signals.
Innovation Solution
A touch panel design incorporating a bias voltage generation circuit, a reverse bias voltage generation circuit, a modulating voltage generation circuit, and capacitors that toggle between display and touch periods to maintain a consistent VGH-VGL limit by coupling modulating voltage signals to output terminals, ensuring the same voltage range as in pure display applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the maximum voltage limit is 32V in a general HV process, then the VGH-VGL difference can be maintained within the limit, but the voltage selection range becomes limited in in-cell and touch applications
Solution Approach 1:
The voltage generation is divided into separate circuits: a bias voltage generation circuit for generating VGH and VGL, and a modulating voltage generation circuit for generating the touch sensing signal. This segmentation allows independent optimization of each circuit's voltage range, enabling the modulating circuit to operate beyond the 32V limit while the bias circuit maintains compliance.
Solution Approach 2:
The patent introduces a time dimension by alternating between display period and touch period operations. During the display period, the bias voltage circuit operates with VGH-VGL < 32V. During the touch period, the modulating voltage circuit operates with higher voltage swings for touch sensing. This temporal separation allows the system to achieve both compliance and extended voltage range.
2Adaptability or versatility
If the bias voltage generation circuit and reverse bias voltage generation circuit are used during display period, then the display performance is maintained, but the voltage range is restricted during touch period
Solution Approach 1:
The system operates in periodic cycles alternating between display period and touch period. During the display period, the bias voltage generation circuits are activated to maintain display performance. During the touch period, these circuits are deactivated and the modulating voltage generation circuit is activated for touch sensing with extended voltage range. This periodic switching resolves the contradiction by allowing different operational modes at different times.
Solution Approach 2:
The voltage generation system is made dynamic by allowing switching between different circuit configurations based on operational mode. The bias voltage generation circuits can be turned on during display period and turned off during touch period, and vice versa for the modulating voltage generation circuit. This dynamic reconfiguration enables the system to adapt its voltage characteristics to the current operational requirements.
Data Source
AI summary
The present invention provides a touch panel and a controlling method thereof. The controlling method comprises: during a display period of the touch panel, turning on a bias voltage generation circuit to generate a bias voltage signal, turning on a reverse bias voltage generation circuit to generate a reverse bias voltage signal, and turning off a modulating voltage generation circuit; during a touch period of the touch panel, turning off the bias voltage generation circuit, the reverse bias voltage generation circuit and turning on the modulating voltage generation circuit to generate a modulating voltage signal, wherein the modulating voltage signal is same as a touch sensing signal of the touch panel; using a first capacitor to couple the modulating voltage signal to the bias voltage generation circuit; and using a second capacitor to couple the modulating voltage signal to the reverse bias voltage generation circuit.