Touch Display Driver Circuit Voltage Surge Control

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Solution Overview

Problem

The integration of touch and display functions in a single chip leads to issues with touch accuracy due to voltage surges during transitions between display and touch sensing cycles, affecting the common electrode and impacting overall performance.

Innovation Solution

The driver circuit adjusts the voltage of the source and gate terminals of the control transistor in transition intervals to minimize voltage surges, using different drive modes and power levels to ensure the common electrode reaches the required voltage quickly and accurately, reducing electromagnetic interference and improving touch and display accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the driver circuit outputs a driving signal with a fixed voltage during display cycle, then the display function operates normally, but voltage surges occur during transition to touch sensing cycle affecting touch accuracy

Engineering Contradiction:

Improvetouch accuracyVSAvoidvoltage surge

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The driver circuit outputs a preliminary driving signal during the transition interval before the touch sensing cycle begins. This preliminary signal adjusts the voltage of the source terminal and gate terminal in advance, causing the common electrode voltage to rise partially before the touch sensing cycle starts, thereby reducing the voltage surge when the touch sensing cycle begins

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The driver circuit changes the voltage parameter of the driving signal during the transition interval. By outputting a driving signal with a voltage different from the display cycle voltage, the circuit adjusts the terminal voltages to reduce the voltage surge that would otherwise occur during the transition to touch sensing cycle

Inventive Principle:

Principle #35Parameter changes

2Speed

If the common electrode voltage is adjusted quickly during transition interval, then touch sensing response is improved, but electromagnetic interference increases

Engineering Contradiction:

Improvevoltage transition speedVSAvoidelectromagnetic interference

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The driver circuit performs preliminary voltage adjustment during the transition interval by outputting a specific driving signal. This causes the common electrode voltage to rise partially before the touch sensing cycle starts, reducing the magnitude of voltage change needed during the actual touch sensing cycle, thereby reducing electromagnetic interference while maintaining fast response

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potentially harmful rapid voltage change into a beneficial preliminary adjustment. By using the transition interval to pre-adjust the voltage, the circuit reduces the voltage surge during touch sensing cycle, transforming what would be electromagnetic interference into a controlled voltage transition that improves touch accuracy

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If integrated touch and display functions are implemented in single chip, then device integration is improved, but voltage surges during cycle transitions affect overall performance

Engineering Contradiction:

ImproveintegrationVSAvoidperformance accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The driver circuit outputs a preliminary driving signal during the transition interval between display cycle and touch sensing cycle. This preliminary signal adjusts the voltage of control transistor terminals in advance, causing the common electrode voltage to rise partially before touch sensing begins, thereby reducing voltage surges that would affect performance accuracy in the integrated device

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The driver circuit changes the voltage parameter of the driving signal during the transition interval to a value different from the display cycle. This parameter change adjusts the terminal voltages to reduce voltage surges, maintaining performance accuracy while preserving the integrated touch and display functions

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250244846A1Touch display device and driver circuit

Publication Date: 2025.07.31 NOVATEK MICROELECTRONICS CORP

AI summary

A touch display device is provided. The touch display device includes a touch display panel and a driver circuit. The touch display panel includes a control transistor coupled to a common electrode through a liquid crystal capacitor. The driver circuit is coupled to the touch display panel, and outputs a first driving signal to a first terminal of the control transistor. When the touch display panel switches from a first operational cycle to a first transition interval, the driver circuit adjusts the first driving signal to change a voltage of the first terminal of the transistor from a first voltage to a second voltage different from the first voltage to adjust a voltage of the common electrode.