Touch Panel

The touch panel is an input device, so it needs to be combined with a display and a PC or other device to make a complete touch input system. This is the main structure. • Cover Lens - Can be made of composed of glass, PET, PC or other plastic film. This primarily serves to protect the touch sensor and act as an electrical insulator, though it can also be a functional part of the product, in the case of resistive technology. • Touch Sensor - this is wear the circuity for the touch screen is located and it acts to collect and process the touch signal • Controller - The controller connects between the touch sensor and the PCB. It takes information from the touch sensor and translates it into information that the PCB can understand and act on. • COF - The controller can be located on a chip mounted on the product’s FPC (this is known as Chip on Film – or COF). • COB - The controller can also be on a separate PCB (known as COB – Chip on Board). • Software Drivers - The driver allows the touchscreen and PCB to work together. It tells the computer’s OS how to interpret the touch information that is sent from the controller. Most touch screen drivers today are a mouse emulation type - this makes touching the screen the same as clicking your mouse at the same location on the screen. This allows the touchscreen to work with existing software eases application development costs and lead times. • FPC - a flat printed circuit cable (FPC or FFC) that is used to send data from the screen to the controller, or the display to the board. • OCA / COF - OCA is a dry sheet adhesive used to bond the display to the touch panel and deliver superior performance than tape bonding, it is also used to bond a plastic cover lens to the touch sensor. COF is the bonding method usually used to bond the touch sensor to the cover panel. • Tape Bonding Adhesive - the double-sided adhesive used to bond the display and touch panel in case of perimeter or tape bonding. • Assembly Gasket - The gasket supplied to prevent dust from entering the touch assembly in the gap between the display and the touch panel

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Cover Lens

The cover lens is a protective plastic or glass layer that is optically bonded to the top of the touch sensor in order to protect the touch sensor from scratching, wear, chemicals, etc.. The cover lens is often hardened by various methods to make it even more durable, and can also have a variety of filters or enhancements added to it to improve the performance (e.g. glare reduction, anti-fingerprint coatings, etc..) of the touch display for certain applications or markets. Cover lens design can also be customized in a wide range of ways, in terms of shape, logo and button printing, bezel shape, etc..

Cover Lens Thickness

• Standard cover lens thicknesses: 0.7, 1.1, 1.8, 3.0, 5.0mm • Custom cover lens thickness can range from 0.55mm to 6mm • Cover lens with a thickness >3mm is generally classified as automotive glass and has an inferior cosmetic appearance and optical clarity. • Tolerances will be listed in product drawings • If thickness is ≥1.8mm, the dimensional tolerance = 0.2mm. • If thickness is less than <1.8mm, standard dimensional tolerances will be 0.05mm. • Currently, Dignity typically uses optical bonding COF to bond the cover lens and touch sensor components.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Cover Lens – Material Choices

Cover lens can be made of plastic materials (PET, PC, composite) or different varieties of glass (soda lime, borosilicate, chemically strengthened, heat tempered, special scratch resistant types like Corning Gorilla Glass, Asahi Dragontrail, etc..)

• Heat Strengthening – Is appropriate for many applications and materials where a full temper is not possible due to thickness, size, low thermal expansion rate of the base material, or other application requirements. This process does not produce a full “dicing” pattern when the glass is broken. It is cheaper and easier to produce than C/S glass. • Heat Tempering - Heat tempered glass is standard glass that is heated to a 600⁰C+ and then blasted with jets of cold air to rapidly cool. This also increases the glass’ strength.HT is appropriate when small size fragments (dicing) are required when the glass is broken. Heat tempering will cause some optical distortion. • Chemically Strengthening - Chemically strengthened glass (C/S glass) is usually 2mm thick or below; it is strengthened by immersing glass in a chemical bath to increase its strength by ion exchange. It is appropriate for thin glass, very thick glass, complex-shaped glass parts, or where minimal optical or mechanical distortion is desired. It typically provides 5 to 8 times the strength of annealed glass. • HIE Glass – this includes Gorilla Glass, Dragontrail and others -generally the cost is too high for most applications. These are made of ion-exchange aluminosilicate; strength is similar to chemically strengthened glass (6 –8 times stronger than normal glass), but surface hardness is superior (8-9H)

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Cover - Material Choices (Chart)

Thickness (mm) Material Hardness Strength Optics Price Comments Min Max

PC 1H Poor Medium Medium Easily Scratched

PET 3H Medium Poor Low Easily Scratched

Soda Lime Glass 0.55 3 5H - 7H Poor Excellent Low Common glass

Heat Strengthened 0.55 3 6H Medium Good Low Does not anneal

Chemically Strengthened (CS) 1.1 3 7H Good Good Medium / High ≤3 mm thickness

Heat Tempered 3 6 7H Good Poor Medium ≥3 mm thickness

Borosilicate Glass 0.55 7.5H Good Medium High Heavy

Gorilla / Dragontrail 0.55 1.1 7H - 9H Excellent Medium Very High High Cost

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Cover Lens – Material Choices

Cover Lens – Decorative Options • Decorative Printing • Borders • Logos • Text • Various Colors • Bezels – a variety of rounded, square, pencil edge, etc.. bezels • Machined Cutouts • Custom Shapes • Custom Screen Size • LED Windows

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Enhancements

An introduction to some of the terms regarding touch panel enhancement.

• Front of Screen (FOS) - these are enhancements that are literally placed in front of the display; they can be either placed on the cover lens or the touch sensor.

• Filters - these are enhancements that come generally in precut sheets and are applied directly to the front of the display or between the touchscreen and display.

• Screen Optical Coatings / Enhancements - these are a variety of enhancements that are directly applied to the touch screen or cover lens and usually affect the viewing / optical qualities of the touch panel. They can be applied by sputtering, thin coating, dip coating, etching, etc..

• Embedded Enhancements - these are enhancements that are included during the production process, usually by the addition of various materials to provide enhanced performance for the final product.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Filters and enhancements (Chart)

Material Effect Cost Considerations The irregular surface, diffuse light and reduce Coated or etched, etched is more Anti-Glare (AG) Medium glare, increase contrast and readability durable but costly Coating that reduce reflections, increase Anti-Reflective (AR) High Should be used along with AF contrast and readability Anti-Fingerprint (AF) Resist fingerprint oils, dirt and water Low Short lifespan (1-3 years) Prevent the glass from falling out of the cover Anti-Shatter Film (ASF) Low Subtract thickness glass or display Screen out EMI resistance to improve touch EMI Resistance - ITO Medium Resistance level is low performance Screen out EMI resistance to improve touch High level of resistance, but lower the EMI Resistance - Mesh Very High performance transmittance Dead Front Blocks display light, reduce transmittance Low Can be a film or printed Mirror Effect Creates a mirror-like reflective surface Medium Durability and wear issues

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Filters and enhancements - Other

There are more filters and enhancement but are less common.

• UV/IR Filters – Fil layers that can be added to a display. This help filter various light wavelengths. This might improve the display lifespan for exterior uses. • Transparent heaters – Transparent heaters expand the operating temperatures of flat panel displays and backlights, this improves the performance at very low temperatures. • Colored Filters – A variety of colored filters can improve the contrast of some elements, or be used to provide an aesthetic effect. • Anti-Corruption – Prevents some materials and corrosive to stick to the screen such as sharpie ink. • Anti-Microbial (AM/AB) – Typically used for healthcare applications, it is a material that inhibits bacterial growth which can be incorporated in the product housing or as a filter to the surface of the touch screen. • Hard Coating – Applied to some plastic covers to achieve up to 9H hardness for anti-scratch purposes. It is extremely expensive and sometimes surpass the cost of Gorilla Glass or HIE glass. • Privacy Filters – Privacy filters guard the security of on screen data and stop off-axis viewing of the display by blocking the light on either side, this blacks the angle of the screen to any viewing angle greater than 30 degrees.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Touch Sensor Structure

A touch sensor is composed of two layers of X and Y sensing electrodes that are overlaid in a grid in order to detect touch location. The touch data is then routed around the edge of the sensor when trace wires (generally made of AG silver) route down to the bottom and attach to an FPC or other flexible connector.

SITO (Single sided ITO) - This means that the touch sensor’s X and Y layers are separated onto two layers of material. This can be the underside of the cover lens and the top of the touch sensor for GF and GG, or on two layers of film for GFF.

DITO (Double sided ITO) - This means that the touch sensor’s X and Y layers are placed one on each side of the touch sensor, so that a complete sensor can be made on a single layer of material.

Channels (X + Y) - The number of channels helps to determine the precision and the resolution of the touch screen, but at the same time a higher number of channels requires more processing power, a higher powered IC and more traces to route this information to the FPC. Very fine traces can require lasers to create.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Controller

The controller is a miniature PC card that acts as the bridge between the touch sensor and the main PCB.

It contains a microprocessor, analog to digital converters and microchips to allow communication with PCB. It also powers the touch screen and interprets the information received from the touch screen. It work by filtering the touch screen data and converts it into touch coordinates for the PCB to act upon.

Higher performing controllers can also be used to filter touch screen data in order to detect abnormal or false touches and filter them out. Many controllers can now be tuned to ignore LCD noise, to reject palm “touches”, to improve functionality with liquids on the screen, etc..

Controllers can be classified into two large types: • COF – Chip on Flex – the controller is mounted on the touch screen FPC • COB – Chip on Board – the controller is mounted on a separate PCB that is connected via separate FPC

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions IC Selection

There are a wide choice of companies producing specialist touch controllers, as well as a large range of IC specifications. The choice of an IC is largely dependent on a few key factors: • Cost considerations • Number of touch points required • Touch panel size (Number of channels supported) • Operating system and software support (particularly for certain less widely used embedded software platforms or types) • Interfaces supported • Operating environment • Temperature • EMI considerations • Glove use and splash resistance

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Firmware and Software. Touch special performance

Certain applications Will have special performance requirements that may require special tuning, an enhanced IC to provide better sensitivity or special gestural and touch support. Such as: • Multi-touch – Most standard ICs will deliver at least 10 touch points. This can be increased to as many as 50-60 touch points for large format products, but this mean a significant increase in cost. • Gloved Touch - Touch panel can still register touch, even if the using is wearing gloves. However the thickness and material of the gloves (Cotton, nitrile, rubber, etc.) are key points. • Water Resistance / Rejection – The screen can still register touch, even if there is some water splashed over the screen. • Improved EMI Resistance – Touch panel can still function well even in the presence of a large amount of EMI (Electronic noise), either from the LCD or external sources. • Passive Stylus – A passive (I.E. No external power source or electronic signal) can be used with the touch panel. • Palm Rejection – Usually for larger touch screens where the hand may be placed flat on the screen.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Adhesives

A variety of adhesives are used both to bond the touch screen to the cover lens as well as to bond the touch screen assembly to the display.

Optical Bonding Adhesives • OCA. A dry, sheet adhesive that is die cut from rolls of film. • OCF. A dual curing sheet adhesive that is easily reworked; uses heat/vacuum as well as UV light to cure. • LOCA. A liquid optical adhesive that is dispensed via computer aid and dual cured to aid rework-ability.

Industrial Tapes • 300 Series. 3M double sided tape. Good adhesion and durability. • VHB. 3M’s high end product line; superior adhesive and durability qualities. • Acrylic. A low end, low durability industrial adhesive. • Sealing gaskets can also be incorporated for dust proofing or waterproofing.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Driving Board

An LCD controller board contains the hardware needed to: • Output images to the LCD panel in the format it needs. • Drive the LCD panel’s backlight. • Run any additional componentry (such as OSD). • It sits between the LCD panel and the computer you’re using to display imagery (or the tablet/phone’s motherboard). • It typically needs to convert a signal from HDMI/DisplayPort to whatever format the LCD panel uses.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions Display Partners

Our company’s supply chain in the Pearl River Delta includes some of the world’s leading LCD manufacturers. We can source a wide range of LCD sizes and specifications quickly and easily at a cost- competitive level. Display selection depends on a number of key factors, and our experienced project engineers can help you find a display that meet’s your projects technical and budgetary needs. Some of the factors to consider: • Display size, viewing area and active area. • Display brightness. • Power consumption. • Display lifespan (hours). • Operating environment (temperature range). • Interface type.

www.dignity.com.cn Dignity Electronics | HMI Touch Solutions