TDDI IC Common Voltage OPAMP Multiplexing for Pin Reduction

Solution Overview

Problem

Existing touch and display driver integration (TDDI) ICs in LCD touch screens require complex circuits and high power consumption, leading to increased pin count, chip area, and power usage, which degrades overall performance.

Innovation Solution

A hybrid control circuit with a reference voltage generator, touch-sensing waveform generator, multiplexer, and shared common voltage operational amplifier (OPAMP) is used to drive the TDDI IC, allowing for efficient display and touch-sensing control through a common voltage path, reducing the need for multiple OPAMPs and pin counts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple separate circuits (sensing waveform generator, sensing OPAMPs, VCOM-OPAMPs, multiplexers, ADCs) are implemented in TDDI ICs, then display and touch-sensing control functions are achieved, but pin count increases, chip area increases, and power consumption increases

Engineering Contradiction:

Improvedisplay and touch-sensing control functionsVSAvoidpin count

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The common voltage OPAMP is designed to perform multiple functions: it serves as the VCOM-OPAMP during display phase and as the sensing OPAMP during touch-sensing phase. This multi-functionality eliminates the need for separate sensing OPAMPs and VCOM-OPAMPs, reducing pin count and chip area while maintaining both display and touch-sensing control capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the sensing waveform generator and VCOM generator into a single hybrid control circuit. The multiplexer is used to switch between different output modes of the same OPAMP, combining multiple functions into unified circuitry that reduces overall complexity and component count

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If multiple separate circuits (sensing waveform generator, sensing OPAMPs, VCOM-OPAMPs, multiplexers, ADCs) are implemented in TDDI ICs, then display and touch-sensing control functions are achieved, but chip area increases

Engineering Contradiction:

Improvedisplay and touch-sensing control functionsVSAvoidchip area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The common voltage OPAMP is designed to perform multiple functions: it serves as the VCOM-OPAMP during display phase and as the sensing OPAMP during touch-sensing phase. This multi-functionality eliminates the need for separate sensing OPAMPs and VCOM-OPAMPs, reducing pin count and chip area while maintaining both display and touch-sensing control capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the sensing waveform generator and VCOM generator into a single hybrid control circuit. The multiplexer is used to switch between different output modes of the same OPAMP, combining multiple functions into unified circuitry that reduces overall complexity and component count

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If multiple separate circuits (sensing waveform generator, sensing OPAMPs, VCOM-OPAMPs, multiplexers, ADCs) are implemented in TDDI ICs, then display and touch-sensing control functions are achieved, but power consumption increases

Engineering Contradiction:

Improvedisplay and touch-sensing control functionsVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The common voltage OPAMP is designed to perform multiple functions: it serves as the VCOM-OPAMP during display phase and as the sensing OPAMP during touch-sensing phase. This multi-functionality eliminates the need for separate sensing OPAMPs and VCOM-OPAMPs, reducing pin count and chip area while maintaining both display and touch-sensing control capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system operates in periodic phases, switching between display phase and touch-sensing phase. The multiplexer routes signals appropriately based on the current phase, allowing the same OPAMP to be used for different functions at different times, thereby reducing overall power consumption compared to having always-active separate circuits

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS10976857B1Method and apparatus for driving touch display driver integrated circuit of touch-sensitive display panel

Publication Date: 2021.04.13 HIMAX TECH LTD

AI summary

A method and apparatus for driving a touch display driver integrated circuit (TDDI) of a touch-sensitive display panel are provided. The method may include: in a display phase of the touch-sensitive display panel, utilizing a reference voltage generator to generate a reference voltage having a predetermined voltage level to be a common voltage of the touch-sensitive display panel, and utilizing a common voltage operational amplifier (OPAMP) to drive the common voltage to the TDDI IC through a common voltage path, for performing display control of the touch-sensitive display panel; and in a touch-sensing phase of the touch-sensitive display panel, utilizing a touch-sensing waveform generator to generate a touch-sensing waveform signal carrying at least one touch-sensing waveform, and utilizing the common voltage OPAMP to drive the touch-sensing waveform signal to the TDDI IC through the common voltage path, for performing touch-sensing control of the touch-sensitive display panel.