Touch panel

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SSG Simple Sensor Glass


ITO Indium-Tin-Oxide

SITO Single-sided ITO layer

DITO Double-sided ITO layer


Bonding Overview

OCA Optical Clear Adhesive (dry bonding)

LOCA Liquid Optical Clear Adhesive (wet bonding) [1]

OCR Optical Clear Resin [2]

Air Gap



Production of OGS [3]

Touch Technologies

Projected Capacitive Touch

Self Capacitance

Capacitance of a single electrode to ground is increased by the human body capacitance while touching.

Type self.png Cs_touch = Cs + Cg

Advantages Disadvantages
Simple, low-cost limited to 1 or 2 touches
single layer possible lower accuracy
long distance field protection
active guard possible
fast measurement

Mutual Capacitance

Capacitance between two electrodes is decreased by human body capacitance while touching.

Type mutual.png Cs_touch = Cs_idle – Cg

Advantages Disadvantages
detect 2 and more touches more complex, higher cost
higher touch accuracy two layers needed (or 1 layer with bridges)
flexible in pattern design

Surface Capacitive Touch


Advantages Disadvantages
excellent drag performance with extremely smooth surface no multi-touch possible
resistant to contamination calibration drift & susceptible to EMI

Resitive Touch

  • Analog Resistive
  • Analog Multi-Touch Resistive (AMR)

Digital Multi-Touch Resistive (DMR)

Advantages Disadvantages
multi-touch poor durability (PET top surface)
simple & familiar resistive technology poor optical performance
Lower cost than p-cap Non-zero touch force

Acoustic Touch

  • Surface Acoustic Wave (SAW)
  • Acoustic Pulse Recognition (APR)
  • Dispersive Signal Technology (DST)

Optical Touch

  • Traditional Infrared (IR)
  • Waveguide Infrared
  • Multi-Touch Infrared
  • Camera-Based Optical
  • Planar Scatter Detection (PSD)
  • Vision-Based

Force Sensing Touch

Touch Structures


A standard touch screen is laminated directly on top of the LCD module.

One Glass Solution (OGS)

Sensor on cover-glass

Structure OGS.png

Glass on Glass (GG)

Sensor on separate glass

Structure GG1.png Structure GG2.png


The touch sensor is an X-Y array of capacitive electrodes deposited on the top or bottom surface of the color-filter substrate.

On-Cell / In-Cell structure[4]


The touch sensor is physically inside the LCD cell. (pixel electrode can be shared)

Charge Sensing (In-Cell)

Surface Treatments

anti-glare AG

Changes specular reflection into diffuse reflection

anti-fingerprint AF

anti-reflection AR

Reduces specular reflection


anti-corruption AC allows permanent Sharpie ink to be wiped off

anti-microbial AM for healthcare applications

anti-bacterial AB for healthcare applications

anti-stiction reduces finger-sticking friction

anti-crack coating increases durability at lower cost than Gorilla glass


Fundamentals of Projected-Capacitive Touch Technology

Information DISPLAY "LCD In-Cell Touch"