3M MicroTouch ClearTek II Quick setup guide

MicroTouch™ClearTek™II
Integration Guide
3M Touch Systems
Read and understand all safety information
contained in this document before using this product.
3M Touch Systems Proprietary Information

2 MicroTouch™ ClearTek™ II Integration Guide
The information in this document is subject to change without notice. No part of this document may be reproduced or transmitted
in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of 3M Touch
Systems, Inc. 3M may have patents or pending patent applications, trademarks, copyrights, or other intellectual property rights
covering subject matter in this document. The furnishing of this document does not give you license to these patents, trademarks,
copyrights, or other intellectual property except as expressly provided in any written license agreement from 3M Touch Systems,
Inc.
The information provided in this document is intended as a guide only. For the latest detailed engineering specifications, please
contact your 3M Touch Systems, Inc. Application Engineer. 3M Touch Systems, Inc. is committed to continually improving
product designs, as a result, product specifications may be subject to change without notification.
"RoHS Directive compliant" means that the product or part does not contain any of the following substances in excess of the
following maximum concentration values in any homogeneous material, unless the substance is in an application that is exempt
under RoHS: (a) 0.1% (by weight) for lead, mercury, hexavalent chromium, polybrominated biphenyls or polybrominated
diphenyl ethers; or (b) 0.01% (by weight) for cadmium. Unless otherwise stated by 3M in writing, this information represents
3M’s knowledge and belief based on information provided by third party suppliers to 3M."
NOTICE: Given the variety of factors that can affect the use and performance of a 3M Touch Systems, Inc. Product (the
“Product”), including that solid state equipment has operation characteristics different from electromechanical equipment, some
of which factors are uniquely within User’s knowledge and control, it is essential that User evaluate the 3M Touch Systems, Inc.
Product and software to determine whether it is suitable for User’s particular purpose and suitable for User’s method of
application. 3M Touch Systems, Inc. statements, engineering/technical information, and recommendations are provided for
User’s convenience, but their accuracy or completeness is not warranted. 3M Touch Systems, Inc. products and software are not
specifically designed for use in medical devices as defined by United States federal law. 3M Touch Systems, Inc. products and
software should not be used in such applications without 3M Touch Systems, Inc. express written consent. User should contact
its sales representative if User’s opportunity involves a medical device application.
IMPORTANT NOTICE TO PURCHASER: Specifications are subject to change without notice. These 3M Touch Systems,
Inc. products and software are warranted to meet their published specifications from the date of shipment and for the period
stated in the specification. 3M Touch Systems, Inc. makes no additional warranties, express or implied, including but not
limited to any implied warranties of merchantability or fitness for a particular purpose. User is responsible for determining
whether the 3M Touch Systems, Inc. Products and software are fit for User’s particular purpose and suitable for its method of
production, including intellectual property liability for User's application. If the Product, software or software media is proven
not to have met 3M Touch Systems, Inc. warranty, then 3M Touch Systems, Inc. sole obligation and User’s and Purchaser’s
exclusive remedy, will be, at 3M Touch Systems, Inc. option, to repair or replace that Product quantity or software media or to
refund its purchase price. 3M Touch Systems, Inc. has no obligation under 3M Touch Systems, Inc. warranty for any Product,
software or software media that has been modified or damaged through misuse, accident, neglect, or subsequent manufacturing
operations or assemblies by anyone other than 3M Touch Systems, Inc. 3M Touch Systems, Inc. shall not be liable in any
action against it in any way related to the Products or software for any loss or damages, whether non-specified direct,
indirect, special, incidental or consequential (including downtime, loss of profits or goodwill) regardless of the legal
theory asserted.
Copyright © 2004 - 2006 3M All rights reserved.
Document Title: MicroTouch™ ClearTek™ II Integration Guide
Document Number: 19-278, Version 13
MicroTouch, the MicroTouch logo, and ClearTek, are either registered trademarks or trademarks of 3M in the United States
and/or other countries.
Windows and/or other Microsoft products referenced herein are either registered trademarks or trademarks of Microsoft
Corporation in the U.S. and/or other countries.
Linux is a registered trademark of Linus Torvalds in the U.S. and/or other countries
Dremel is a registered trademark of Robert Bosch Tool Corporation
Volara is a registered trademark of Voltek Corporation.
3M Touch Systems Proprietary Information

Contents
About This Manual
What You Need to Know ...........................................................................................6
Important Safety Information.....................................................................................6
Explanation of Symbols .............................................................................................7
Important Notes for Video Displays ..........................................................................8
3M Touch Systems Support Services.........................................................................8
Contact 3M Touch Systems .......................................................................................8
Chapter 1 Getting Started
Installation Warnings and Safety Precautions............................................................9
Preparing Your Work Space.....................................................................................10
Identifying the Components .....................................................................................11
Testing the Display Video........................................................................................11
Optional Power Supply for a Serial Controller ........................................................12
Summary of the Installation Procedure ....................................................................12
Chapter 2 Touch Screen Design Considerations
Design Considerations..............................................................................................13
Electrical Considerations..........................................................................................13
Mechanical Considerations ......................................................................................15
Touch System Location............................................................................................17
Designing Software Applications.............................................................................18
Chapter 3 Installing a 3M Touch Systems Touch Screen
Installation Considerations.......................................................................................21
Disassembling the Display .......................................................................................22
Fitting the Touch Screen ..........................................................................................23
Mounting the Touch Screen to the LCD Panel ........................................................24
Inspect the Mounted Touch Screen ..........................................................................27
Repair or Removing the Touch Screen (if needed) ..................................................27
Adding a Sealing Gasket to the Bezel ......................................................................28
Adding Spacers to the Bezel ....................................................................................28
Reconnecting the Bezel and Chassis ........................................................................30
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4 MicroTouch™ ClearTek™ II Integration Guide
Chapter 4 Installing the Touch Screen Controller
Types of Touch Screen Controllers..........................................................................31
Disassembling the Chassis .......................................................................................32
Mounting the Touch Screen Controller Internally ...................................................33
Completing Controller Mounting.............................................................................34
Powering the Touch Screen Controller ....................................................................35
Locating Power for the Touch Screen Controller.....................................................36
Modifying the Display for the Controller Cable ......................................................37
Using Your 3M Touch Systems Touch Screen ........................................................38
3M Touch Systems Proprietary Information

About This Manual
Congratulations on the purchase of your MicroTouch™ ClearTek™ II touch screen and
welcome to the world of 3M Touch Systems — a world where using a computer is as
simple as touching the screen.
The ClearTek™ II touch screen, 3M Touch System’s innovative design for flat capacitive
touch screens, incorporates advanced production techniques that result in high quality
capacitive touch screens. The ClearTek™ II touch screen’s sleek design provides easy
installation in LCD displays. The clear border and wide viewing area, combined with
durability, reliability, high transmission, and superior optical clarity, make the
ClearTek™ II touch screen the ideal choice for all your touch applications.
ClearTek™ II touch screens are available in a variety of sizes, for use on a variety of
displays. These touch screens come in three different configurations:
• With a 5-pin connector to attach to an EX II 7700 series controller;
• Mated with an EX II 7700 series controller;
• With a 12-pin connector for EX II 1700 and EX II 5700 series controllers.
Each ClearTek™ II touch screen requires an EX II touch screen controller. These
controllers come in different form factors and may be cased or uncased; refer to the
appropriate EX II Controllers Reference Guide and the MT 7 Software User Guide for
more information on your touch system. All technical documentation is available from
the 3M Touch Systems website at http://www.3Mtouch.com/.
3M Touch Systems, Inc. is committed to being a premier supplier in touch systems
throughout the world. As a 3M Touch Systems, Inc. customer, you are aware that we
have strong internal programs that meet or exceed environmental regulations of our
customers and the regions in which we conduct business.
As such, our approach to the European Union Directives 2002/96/EC (WEEE) and
2002/95/EC (RoHS) (the directives) is being addressed in the same rigorous manner. To
ensure compliance with the directives, we are pleased to provide this RoHS directive
compliant product.
3M Touch Systems Proprietary Information

6 MicroTouch™ ClearTek™ II Integration Guide
What You Need to Know
WARNING
To avoid the risk of electric shock which could result in serious injury or death:
You must be a qualified technician with experience in assembling and disassembling
different types of displays. You must know the specifics of your display and have
access to its documentation.
There may be hazardous voltages present in the display. If you do not understand
display electronics, you may injure yourself, damage the touch screen, or damage the
touch screen controller.
This manual describes how to complete the following tasks:
• Disassemble your display (if necessary)
• Mount the touch screen to the LCD panel
• Install the touch screen controller
Important Safety Information
Read and understand all safety information before using this product. Follow all
instructions marked on the product and described in this document. Pay close attention to
the following installation warnings and safety precautions.
Intended Use
The MicroTouch™ ClearTek™ II Integration Guide is intended to instruct and guide
you in the integration of a ClearTek™ II touch screen into an existing flat screen
display. This manual provides specific instructions for an LCD panel with chassis
attached to the front bezel, but these same steps apply to the majority of integrations.
These touch screens are intended for indoor use only and are not designed for use in
hazardous locations.
Explanation of Signal Word Consequences
DANGER: Indicates a potentially hazardous situation, which, if not avoided,
will result in death or serious injury and/or property damage.
WARNING: Indicates a potentially hazardous situation, which, if not avoided,
could result in death or serious injury and/or property damage.
CAUTION: Indicates a potentially hazardous situation, which, if not avoided,
may result in minor or moderate injury and/or property damage.
CAUTION: Indicates a potentially hazardous situation, which, if not avoided, may
result in property damage.
DANGER
To avoid the risk of fire and/or explosion which will result in serious injury or
death:
• Do not install or use this product in a hazardous location.
3M Touch Systems Proprietary Information

About This Manual 7
WARNING
To avoid the risk of electric shock which could result in serious injury or death:
• Do not use a damaged power supply.
• Do not use a power cord that is frayed or otherwise damaged.
• You must be a qualified technician with experience in assembling and
disassembling different types of displays. You must know the specifics of your
display and have access to its documentation. There may be hazardous voltages
present in the display. If you do not understand display electronics, you may injure
yourself, damage the touch screen, or damage the touch screen controller.
To avoid the risk of fire and/or explosion which could result in serious injury or
property damage:
• Do not install or use this product in a hazardous location.
• Do not use this product in any outdoor environment unless NEMA (or other
similar) standards, such as IP rating, are followed.
CAUTION
To reduce the risks associated with improper disposal, which if not avoided may
result in minor or moderate injury from ground water contamination:
• Dispose of components in accordance with local, state, and federal regulations.
CAUTION
To avoid the risk of glass breakage which may result in minor or moderate
injury:
• Handle the touch screens with care to avoid breaking the glass. Be aware of
cracked or broken touch screens with sharp edges.
• If you need to remove the touch screen for servicing, do not try to pry the touch
screen off the LCD panel. You may break the glass and injure yourself or others.
To avoid the risk of electric shock which may result in minor or moderate injury:
• Do not service the monitor.
• Do not use non-conforming replacement parts.
• Do not place wet or damp objects on the monitor.
• Do not expose the monitor to rain or other sources of water, steam, or moisture.
• Do not place foreign objects on the monitor or its cables.
To avoid the potentially hazardous situations associated with the use of isopropyl
alcohol which may result in minor or moderate injury or property damage:
• Follow all instructions and recommendations in the manufacturer's Material Safety
Data Sheet and product label.
To avoid possible environmental contamination which may result in minor or
moderate injury:
• Dispose of the monitor according to applicable governmental regulations.
Explanation of Symbols
Attention: Read accompanying documentation
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8 MicroTouch™ ClearTek™ II Integration Guide
Important Notes for Video Displays
• Plug power cord into an appropriate power source.
• Plug power cord into a grounded receptacle.
• When unplugging power supply cord, pull on plug, not cord.
• Do not connect or disconnect this product during an electrical storm.
• Install the display in a well-ventilated area. Always maintain adequate ventilation to
protect the display from overheating and to ensure reliable and continued operation.
• Do not expose the display to direct sunlight or heat. Passive heat may cause damage
to the case and other parts.
• Do not install the display in areas where extreme vibrations may be generated. For
example, nearby manufacturing equipment may produce strong vibrations. The
vibrations may cause the display to exhibit picture discoloration or poor video
quality.
• Ensure that metal enclosures or bezels do not contact the touch screen.
• To avoid ergonomic concerns:
Do not install the monitor in a manner or location with awkward accessibility.
Extended use may result in muscle, tendon, or fixed posture strains. It is
recommended you take periodic breaks from continuous use.
3M Touch Systems Support Services
3M Touch Systems provides extensive support services through our website and
technical support organization. Visit the 3M Touch Systems website at
http://www.3Mtouch.com/, where you can download touch screen software and drivers,
obtain regularly updated technical documentation on 3M Touch Systems products, and
learn more about our company.
Whenever you contact Technical Support, please provide the following information:
• Display manufacturer and model number
• Touch screen part number and serial number
• Current driver version
• Operating system used
• Information on additional peripherals
Technical Support is available Monday through Friday 8 a.m. to 8 p.m. US Eastern
Standard Time – 9 a.m. to 5 p.m. throughout Europe.
You can contact 3M Touch Systems Technical Support (US only -- Eastern Standard
Time) by calling the hot line, sending email or a fax.
• Technical Support Hot Line: 978-659-9200
• Technical Support Fax: [phone]
• Toll Free: 1-866-407-6666
• Email: [e-mail]
Contact 3M Touch Systems
Contact information for all offices can be found on our website at:
http://www.3Mtouch.com/.
3M Touch Systems Proprietary Information

CHAPTER 1
Getting Started
The 3M Touch Systems touch screen is the most intuitive interface available for the PC
today. Touch screens make using computers as simple as touching the screen. To begin
installing your 3M Touch Systems touch screen, take a few minutes to review this
chapter. It is your roadmap to a successful installation. This manual describes how to
retrofit an LCD display with a touch screen. However, the principles apply equally well
to larger systems integrated with touch screens at an OEM level.
• Pay close attention to the installation warnings and safety precautions. Disassembling
a display can be a dangerous procedure. Be sure to follow all manufacturers'
recommendations for assembly and disassembly of your flat screen display.
• Make sure you have the necessary equipment before starting the installation. Refer to
Supplies and Tools Needed for the Installation later in this chapter.
• Set up a clean, comfortable, and spacious working area. Having sufficient room to
work makes the installation easier.
• Test your display to ensure good working condition before you install the touch
screen.
• Identify the different components to install and review the summary of the
installation procedure. It is important to know how all the pieces eventually fit
together before disassembling your system.
Note: If any points within this guide are unclear to you, or further clarification is
necessary, please contact your 3M Touch Systems applications engineer.
Installation Warnings and Safety Precautions
3M Touch Systems recommends that only qualified display technicians install the touch
screen for the following reasons:
• Due to the risk of injuring yourself
• Due to the danger of hazardous voltages present in the display
• Due to the risk of accidentally damaging the touch screen
• Due to the risk of altering the LCD’s critical circuits
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10 MicroTouch™ ClearTek™ II Integration Guide
If you decide to install the touch screen, take the following precautions:
• Follow each procedure carefully, work with the system powered off and unplugged,
and observe all warnings.
• Protect your investment. The touch screen is a glass product. You must handle it with
care.
Note: Consult the display manufacturer to find out whether the original warranty will be
affected if you install the touch screen. Also, determine who will recertify the display.
Recertification will be necessary to comply with safety and FCC or CE regulations.
Supplies and Tools Needed for the Installation
Before starting the installation procedure, check that you have all items listed below.
Supplies Needed
• Safety glasses • Clean, anti-static pad
• Small containers for holding loose
parts (coffee cups)
• Foam pad (optional)
• Electrical tape (or black acetate tape) • Felt-tip marker pen
• Clean soft cloth and glass cleaner for
the display and touch screen
• Cable tie-wraps
• Lead-free solder (RoHS compliant)
• Replacement screws for mounting flat
panel to bezel or chassis
• Ring lugs or crimps
• Nylon spacers and washers
• Sealing tape – Flat, closed-cell foam
(single sided adhesive)
• Mounting tape -- closed cell acrylic
foam 3M VHB 4956 (double sided
adhesive)
Tools Needed
• Flat-blade screwdriver with insulated
handle
• Phillips-head screwdriver
• Soldering iron
• 3 ft (1 m) insulated wire with alligator
clips at each end
• 3/32-inch (3 mm) insulating tubing
(or electrical tape)
• Razor knife or single-edge razor blade • Center punch
• Power drill • Variety of drill, tap, and spade bits
• Wire stripper • Dremel® tool or nibbler
• Compressed air (optional)
Preparing Your Work Space
Comfortable Work Area
Select a comfortable work area with adequate space and lighting. Make sure that the area
is free of clutter and/or objects that could scratch the touch screen and flat panel display.
3M Touch Systems recommends an area of at least three square feet. You need this space
to handle components safely and to set major components aside during the installation.
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Chapter 1 Getting Started 11
Protective Material
Place anti-static protective material on the work surface. A padded surface protects
equipment from scratches during installation.
Small Containers
Have several small containers (such as coffee cups) available to hold screws, washers,
and other small components once you remove them.
Foam Pad
A foam pad is useful for holding the display while attaching the touch screen. The pad
makes the screen easier to rotate for fastening screws, taping, etc.
Identifying the Components
The following components are needed for a successful integration:
• A ClearTek™ II touch screen
• An EX II touch screen controller
• A serial cable (7310101) or USB cable (7312256)
• Software and technical documentation found on the www.3Mtouch.com.
Save the invoice, shipping container, and all packing material in case you need to
transport the equipment any time in the future.
Testing the Display Video
Whether you are installing the touch screen on a new or older display, you should make
sure that the display is in good working condition and the video output is functioning
properly. Your initial test should verify that the video functions properly before you
install the touch screen. You can also compare your results with the results you get after
you complete the installation.
If the display is functioning properly, turn off your system, disconnect power plugs, and
disconnect all cables from the display. You are ready to disassemble the display and
install the touch screen.
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12 MicroTouch™ ClearTek™ II Integration Guide
Optional Power Supply for a Serial Controller
If you are using a serial controller, you may need some additional equipment depending
on power and port requirements. Serial controllers include the EX II 1700SC series and
EX II 7700SC series controllers.
When installing a serial controller, you must supply power to the controller. You can use
internal power (using the NOVRAM cable orange/grey/green power wires tap power
from inside the display) or use external power. If you decide to use external power, you
will need a power supply. If you are using a standard 3M Touch Systems RS-232 serial
cable (P/N 7310101), or a cased EX II 1700SC controller, consult your applications
engineer for power supply specifications. For countries that use a 230/240-volt main
system, it may be necessary to purchase a power supply locally.
For the EX II 7700 you can supply internal power +5V to +12 VDC though the 2-pin
power input connector pin 2 (+5V to 12 V) and pin 1 (RTN). A square pin indicator on
the bottom of the board marks pin 1.
Details on the power requirements of the EX II series controllers can be found in the
EX II Serial Controller Reference manual available at http://www.3mtouch.com/.
Summary of the Installation Procedure
Sealing
Gasket
Front bezel Touch
screen
LCD panel
& chassis Touch screen
controller Metal shield
Rear display
housing
Mounting
Tape
You can install a 3M Touch Systems touch screen on most displays. Although each
particular display may have some unique integration considerations, the basic installation
process consists of the following steps:
• Test that the display’s video works properly
• Disassemble the display (if necessary)
• Mount the touch screen to the front of the panel
• Install the touch screen controller (internally or externally)
• Reassemble the display
• Connect the display and touch screen to your computer system
3M Touch Systems Proprietary Information

CHAPTER 2
Touch Screen Design Considerations
Design Considerations
ClearTek™ II touch screens are available in a variety of sizes, for use on a variety of
displays. These touch screens come in three different configurations: one with a 5-pin
connector to attach to an EX II 7700 series controller; one mated with an EX II 7700
series controller; and one with a 12-pin NOVRAM connector for EX II 1700 and EX II
5700 series controllers.
Standard ClearTek II is designed and produced without a backshield and takes advantage
of the superior sensitivity and noise rejection of EX II controllers. Refer to the EX II
Controller Reference Guide for how to select signal frequency for best EMI rejection.
Electrical Considerations
EMI and Shielding
The front surfaces of flat panel displays carry potentials that fluctuate at the harmonics of
display scan frequencies. EX II controllers default to a frequency (95.7 kHz) selected for
best rejection of common LCD frequencies. Refer to the MT7 Software User Guide for
additional information on how to change frequency. All technical documentation is
available from the 3M Touch Systems website at http://www.3Mtouch.com/.
3M Touch Systems Proprietary Information

14 MicroTouch™ ClearTek™ II Integration Guide
LCDs
The primary problem with some new types of LCD displays in a capacitive touch screen
environment is that they generate much more electrical noise than their predecessors. The
excessive electrical noise generated by these displays may couple into the touch screen
circuitry and be interpreted by the controller as a touch signal.
A capacitive touch screen attached to the face of a LCD acts like a large capacitor
meaning that it can be charged or discharged continuously. The capacitor consists of 2
plates: one is the face of the LCD and the other is the touch screen. In addition, some
types of LCDs exhibit varying effective impedence to ground.
Although this document focuses on LCD integration, you should be aware of the
following issues when installing a ClearTek II touch screen to a flat CRT.
CRTs
ClearTek II is not recommended on CRTs. If a CRT must be used, the user must first
ensure that front CRT surfaces are adequately grounded to shield the touch screen from
capacitive coupled noise and from charge build-up.
CAUTION
To avoid the risk of electric shock which may result in minor or moderate injury
or property damage:
Exercise caution when working with an ungrounded faceplate CRT. Because of the
hazards involved, 3M Touch Systems recommends against using this specific type of
CRT monitor in all touch applications.
Follow all instructions and recommendations in the manufacturer's documentation.
When a touch screen integrated monitor, using an ungrounded CRT faceplate, is powered
on, the charge created between the CRT faceplate and the back of the touch screen can be
in excess of 40 kV. With an ungrounded faceplate, the built up charge will dissipate
through the path of least resistance, typically through the touch screen controller.
The risk involved is that this high voltage discharge buildup on an ungrounded faceplate
could result in minor or moderate personal injury due to shock, and/or damage to
electronic components and internal touch circuitry.
3M strongly recommends that customers use a properly grounded CRT faceplate on all
touch screen monitor integrations to prevent damage to the touch screen and/or
controller. The high voltage created by an ungrounded CRT faceplate is outside the
specification range of standard 3M Touch Systems touch screens and controllers.
Resultant damage is not warranteed by 3M Touch Systems.
3M Touch Systems Proprietary Information

Chapter 2 Touch Screen Design Considerations 15
Mechanical Considerations
Tail Routing
To minimize the risk of electromagnetic interference, never run the touch screen tail near
or over the LCD backlight inverter. Although the tail is shielded, the noise generated by
an inverter is broadband and can contain frequencies close to the signal frequency.
The touch screen tail is not a handle. Never pick your touch screen up by the tail. It is an
electrical connection and is not designed for high stress.
Do not place constant stress on the tail during handling or integration. Do not expose the
tail to mechanical stresses as a result of the integration design. Provide adequate slack to
ensure there is no straining on the tail. Avoid lateral pulls that may overstress the
outermost electrical contacts on the glass.
Tail bond and strain
relief area
Always design your touch screen integration with the flex tail exiting from the top or
sides of the display. Never design tail exits from the bottom as spills could accumulate in
the tail attachment area and cause electrical shorting.
A
void creasing the
tail within 0.5 inch
(1.27 cm) of the
strain relief. A soft
bend is acceptable.
The touch screen tail is designed to be flexible, and it may be creased once in a single
direction, in multiple locations along the tail and then secured in position with a light
adhesive tape. Avoid angular creases (45°) to the tail directly in the area of the bond and
tape strain relief.
The touch screen tail should not move freely after assembly. Apply tape or another light
adhesive to secure the tail in a manner that does not apply stress to the tail.
Apply tape or other insulating material to sharp edges to protect the tail. Route the cable
away from sharp edges whenever possible.
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16 MicroTouch™ ClearTek™ II Integration Guide
Sealing Gasket to Bezel
Single-sided tapes, adhered to the bezel, make for easy sealing of the touch screen.
Simply align and adhere the tape to the bezel edge. Gaskets should contact the touch
screen perimeter to ensure a good seal without interfering with the viewing area. Do not
adhere the gasket to the touch screen surface.
Sealing gasket adhered to bezel
3M 4956 VHB
mounting tape
Case
Bezel
Touch screen
LCD
Touch controller
The compression should be evenly distributed to the glass surface. Be aware of and
follow material manufacturer’s recommended compression specifications. 3M Touch
Systems has successfully used Volara® 2AF tape for this purpose.
Proper gasketing is critical to any successful touch screen integration. All displays,
regardless of environment, will be exposed to dust, dirt, spills, and grime and should be
sealed with gaskets. Gasketing is relatively simple and straightforward. It can be either an
o-ring or a flat, closed cell foam gasket applied around the perimeter of the bezel.
We recommend using nonacidic, pH neutral 3M brand tapes to seal your bezel and touch
screen. 3M foam tapes provide superior resistance to moisture and chemicals over other
traditional cellular foam tapes.
Important Note: Be aware that certain sealing materials may contain active chemicals
(such as sulfur, acidic compounds or chlorine) that can, if allowed to diffuse, tarnish the
silver conductors and thus affect the operation of the touch screen. In selecting sealing
materials, it is important to know the chemical compounds used in the formulation and to
avoid chemically active, corrosive, and/or recycled materials made from unknown
elements.
Certain types of neoprene gaskets contain an excess of sulfur that makes them
unacceptable for this purpose. It is essential that the user evaluate this product to
determine whether it is suitable for their particular purpose and method of application.
Common x-ray fluorescence testing by an analytical lab can differentiate gasket
composition.
Mounting Tape to LCD
The touch screen must be mounted such that the spacing between the touch screen and
LCD does not vary due to compression or expansion from touch forces or temperature
changes. For optimal performance, we strongly recommend using 3M brand 4956,
4956F, or 4979F tape for this purpose. Failure to mount the touch screen in this fashion
may result in reduced accuracy.
3M Touch Systems Proprietary Information

Chapter 2 Touch Screen Design Considerations 17
Note: 3M VHB acrylic foam tapes (Product Numbers 4956, 4956F, or 4979F) are well
suited for this purpose. These tapes were chosen for their thermal properties. The typical
Thermal Coefficient of Expansion for these tapes is 1.8 X 10E4 mm/mm/°C.
These recommended tapes have been tested to be stable over the published touch screen
operating temperature range. Any other mounting tape must be tested by the user to
stability requirements before installing in touch screens.
It is essential that the user evaluate this product to determine whether it is suitable for
their particular purpose and method of application.
Caution:The gasket tape should have a minimum thickness of 1/16 inch (1.587 mm).
Avoid using thinner tapes. If thicker tape is needed, it is okay to double the recommended
VHB tape. Do NOT use highly compressible tapes.
Metal Enclosures
Because conductive surfaces can present a stray capacitive loading to the touch screen,
you must be careful when positioning the touch screen near metallic objects or materials.
The following guidelines will help ensure a successful installation.
Do not let any metal — such as metal mounting brackets, screws or the LCD metal
housing — physically contact the front or sides of the touch screen. This could be
recognized as a touch.
In the design phase, avoid metal bezels whenever possible. If your current design has a
metal bezel, ensure that it does not directly contact the touch screen. The bezel should be
appropriately grounded and very rigid. Use insulating tape or gasketing as a spacer.
Be aware that some plastic bezels have conductive paint that could act as a metal bezel so
the same design rules apply in these instances.
Take measures to ensure that a metal bezel presents a constant and stable stray capacitive
path to ground at least during operation. If there is a conductive door or bezel, send a
reset command to compensate for stray capacitance changes. On most enclosures, a reset
can be generated using the door open/close switch.
Touch System Location
Keep in mind the optics of the touch screen. Remember that different sources of light
such as outdoor (natural sunlight) and indoor (incandescent or fluorescent) can cause
different effects when viewing the touch screen.
Remember that lighting changes over the course of a day and depends on weather.
Consider the brightness of an area and how it will affect readability of the computer
display.
Consider using high brightness displays for better readability in bright ambient light
conditions. Remember that sunlight comes in at different angles throughout the year.
What might not be a problem in the summer could be an issue in winter.
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18 MicroTouch™ ClearTek™ II Integration Guide
Electromagnetic interference can cause problems with any electrical device. Be aware of
devices that generate electrical fields, such as radio transmitters, pager transmitters, and
security tag deactivators, and plan your installation accordingly.
Designing Software Applications
With any touch application, the design can be crucial to the usability of the final product.
Clear icons, bright contrasting colors, large buttons, button placement, and simple layouts
will contribute greatly to the success of your installation.
Parallax, the effect of a target object appearing in different positions when looked at from
different angles, is a common problem in many computer applications. The combination
of the touch screen in front of the display and differing heights of users can cause
parallax. When designing your touch system software application, use the following
guidelines to help reduce the effects of parallax.
Position the use
r
sees to touch
Touch screen
• Design large buttons to facilitate touch. Remember that a fingertip is much larger
than a cursor.
Button graphic
A
ctive touch area
• Design larger active border areas for buttons. For example, if the button graphic is 1
inch x 1 inch, the active touch area behind it could be 2 inches x 2 inches.
• Keep buttons away from the edges and corners of the screen. If this is impossible,
make sure the active touch areas extend to the outer edges of the viewing area.
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Chapter 2 Touch Screen Design Considerations 19
Small buttons centered with
extended active touch areas
Large buttons located near
edges
Large buttons on bottom with
active areas extending to edges
• Place buttons horizontally whenever possible. One size does not fit all! Consider the
varying heights of users and thus viewing angles when designing the application.
• Turn off the cursor. Users may inadvertently try to drag the cursor to the correct
location on the screen, emulating moving a mouse, instead of touching the button
directly.
• Design your applications to work with a single touch to activate rather than a double-
touch.
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