Capacitive Touch
Lamination
Surface Treatment
Cover Lens Design Guide

Structure
PolyTouch™
Glass/Glass
OGS
TOL
GFF

The basic capacitive touch panel structure is made by two parts: touch sensor and cover lens. There are two types of touch sensors. First

we have the glass sensor which has advantages in optical performance, durability, and narrow border, then the film sensor which has

advantages in thinness, lightness and facilitates the(or eases) production.

There are two type of cover lens: glass and plastic.
Typical cover lens thickness varies from 0.55, 0.75, or 1.1 mm for mobile devices, up to 3 mm or even thicker for industrial applications.

The dielectric constant of the cover lens and its thickness have a direct impact on the sensitivity of the capacitive touch panels – a thinner

cover lens and/or a higher dielectric constant results in better performance. Plastic (PMMA) has a lower dielectric constant and must be

half the thickness of glass to achieve the same performance.

EDT develops various types of sensor and cover lens combination for the capacitive touch panels: Glass to Glass, Glass to film and One

Glass only. The followings are our available capacitive touch panel structures.

As the demand for advanced user interface continues to evolve, the EDT PolyTouch™ innovation in capacitive touch solution, is an

alternative to touch sensory design that is both easy to implement and highly reliable. Unlike traditional resistive touch panels,

PolyTouch™ technology utilizes unique structural design that exclude the need for sensory film, allowing a much more durable

composition and wider operating environment. Elegant, yet convenient, the PolyTouch™ series is an excellent touch solution

complementary to visual medium for any design. Equipped with various pre-installed functions and commands, each PolyTouch™

panel can be easily integrated and made compatible with either existing or newly developed system for fast implementation and

development. Standard PolyTouch™ design from 3.5" to 7" size offers single touch and multi touch alternatives. Both may be

standardized or customized and be integrated as part of the LCD module.

PolyTouch™ Key Features

1.Glass on glass structure
2.Outstanding performance
   - ITO pattern invisibility
   - High transparency (85% & above)
   - Robust structure
   - High reliability
   *Operation temp.: -20℃ ~ +70℃
   *Storage temp.: -30℃ ~ +80 ℃
3.Cost efficient
   - Cost saving on replacement of cover lens design
   - Better yield rate than conventional lamination processes

The Glass/Glass (G/G) type capacitive touch panel (CTP) has been used for glass cover lens laminated
with glass sensor.

The cover glass is used to protect the sensor glass underneath, and the sensor glass is used to sense the touch points. The sensor glass is coated with two conductive layers of ITO: one for the x-axis, another for the y-axis. There are two types of G/G solutions: double-sided indium-tin oxide (DITO), patented by Apple, and single-sided ITO (SITO) that is the most popular used in the CTP industry.

The overall thickness of EDT’s G/G type CTP can be from 1.1 mm for portable device to 3.5 mm or even thicker for various industrial applications. Advantage for G/G type CTP is that the glass cover lens can be custom made by screen-printed on the rear surface, in-mold decorated (IMD), complex treatment with multiple holes and slots, rounded corners, even bent edges, and in most cases, chemically strengthen to enhance its resistance to external impact.

One Glass Solution(OGS):

First, applying a chemical strengthening process onto mother glass, followed by the application of blackmasking (BM1) and circuitry

layout. Once circuitry is completed, mother glass is then divided into individual size panels, and applied with edge-grinding treatment.

A second step of chemical strengthening process is then applied, followed by optional decoration printing or surface treatment.

Touch on Lens(TOL):

Individual panels are separated from the mother glass and undergone chemical strengthening individually. The glass is then entered

cover lens and blackmasking (BM) process, followed by circuitry application and at last any pattern decoration or surface treatment.

The Glass-Film-Film PCAP solution consists of two film circuits that are optically bonded to a cover lens with Optically Clear Adhesive (OCA). This construction is ideal for users who want the same durability as our Glass-Glass product, while at the same time require a thinner and lighter solution overall.

We are actively engaged in the research of new materials, such as COC/COP film substrates of high reliability (without rainbow effect), and transparent conductive material of low resistance. Indium Tin Oxide (ITO) is the material widely used for transparent conducting electrodes on film substrates in the fabrication of capacitive touch panels, however, it suffers from drawbacks as the display size increases beyond around 21.5 inches, principally as a result of its relatively high electrical resistance which hampers its performance and makes it an unsuitable material choice for some applications. Alternatively, Silver Nanonetworks are promising candidates to replace ITO as transparent conductors in these applications.

OCA
OCR
Optical Bonding
Solar Radiation

EDT Optically Clear CTP

OCA(Optically Clear Adhesive) optical bonding

Common thickness: 150um、175um、200um、250um、500um、800um

EDT Optically Clear CTP

OCR(Optically Clear Resin) optical bonding

What is "Optical Bonding”?

Optical bonding is the process of laminating cover glass or touchscreens to the LCD cell. It is a process that applies a layer of transparent

material such as OCA (Optically Clear Adhesive) or OCR (Optically Clear Resin) between the layers to completely fill the air gap.
The adhesive is completely transparent, the structure and color of the adhesive will not transform through the use of time. Any display in

an outdoor environment or high ambient light conditions can be improved with our matured technology and experience. EDT provides

optical bonding solutions to a wide variety of applications like handheld device for outdoor use, navigation systems, industrial, medical

displays, and ATM equipment, for clear visibility under sunlight or in bright environment.

Optical bonding advantages

Optical bonding has some the following advantages,
(1) Enhanced sunlight readability (~5–10 times, depending on application).
(2) Increased impact resistance (~3–8 times, depending on the bonded cover glass).
(3) High shock and vibration tolerance.
(4) Very low reflectance for touch screens in desired applications.
(5) Greatly enhanced life by protecting the display materials from the humidity.
(6) High-quality optical bonding of performance-enhancing auxiliary components, such as AR, AG, AR/AG/hard coat/anti-smudge

and heater glasses, touch screens, and UV, EMI, and sunlight filters.

Examples
(1) For air gap structure with AR(R1=0.5%), the total specular reflectance is 8.5%, the CR can be calculated below, and it should be

larger than the structure without AR.

(2) For optical bonding(R2+3=0.2%) structure without AR, the total specular reflectance is 4.2%, the CR can be calculated below,

Solar Radiation

Many outdoor products using optically bonded capacitive touchscreen displays are routinely exposed to solar radiation (sunlight). However, long-term exposure to sunlight may cause yellowing, cracking or bubbling of the optical bonding material between the capacitive touchscreen and the display. Our solutions are enhanced to extend the lifespan of optically bonded capacitive touchscreen displays placed in outdoor settings prone to solar radiation.

Test Specification

Applications:

 Outdoor kiosks

 Interactive digital signage

 Port facility systems

 Vehicle or marine systems

 EV Charging Stations

 Fuel Pumps

 Other devices requiring resistance to prolonged sunlight exposure

Anti-Glare
Anti-Reflection
Anti-Fingerprint

Anti-Glare (AG)

When surrounding glare makes display readability difficult, anti-glare (AG) coatings utilize diffusive properties to fragment the ambient light

off the surface, using the concept of constructive interference of light. Diffusion works by scattering specular reflections into a wide viewing

cone, making these undesirable reflected images and glare blurred to the eye.

AG coatings use either diffused particles or etching on the glass surface and can enhance viewing performance. EDT currently provides

one standard types of AG coating, both with superior glare reduction for glass cover lens.

Anti-Reflection (AR)

Using the concept of destructive interference of light, anti-reflective (AR) coatings utilize stacking layers structure over the glass
surfaces that vastly improve the efficiency of the optical performance by increasing transmission, enhancing contrast, and eliminating
ghost images.

1. The transmission rate could reach up to 92% for single side one layer AR coating and 94% for double side two layers AR coating.
2. AR coating is vulnerable against finger prints, therefore extra layer of AF costing is always required.

Anti-Fingerprint (AF)

Anti-Fingerprint (AF) coating is using nano-scale material which has excellent water & oil repellency to make the glass surface having
smooth touch, and prevent glass surface from contamination such as smudging or staining, making the glass surface extra slippery
and easy to clean.

General Design Guide

What is 2D/ 2.5D / 3D Cover glass?

From an Industrial Design point of view, there are 3 types of cover lenses often used in the market today: 2D, 2.5D, and 3D. 2D is the most commonly used type because the manufacturing process is relatively simple , resulting in stable quality and competitive pricing suitable for industrial and medical markets.

Manufacturing processes for 2.5D and 3D cover lenses are much more complex, resulting in lower yield rates, production instability, and higher cost. However, the benefit is an enhanced appearance from its uniquely curved shape, which has led to pervasive adoption of 2.5D and 3D cover lenses for consumer products such as mobile phones and tablets. The trend and usage of these types of cover lenses is gradually growing in other markets such as white goods and automotive.

In conjuction with our cover lens manufacturing partners, we can support all 3 types of cover lenses for our integrated touchscreen solutions. For reference, the design rules for each are summarized here:

2D cover lens design rule

2.5D cover lens design rule

3D cover lens design rule

A-Dual Curve

B-Single Curve

C-S type Curve