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Maximizing Hardware & Software Selections for Advanced Touch Screen Applications. Michael Woolstrum CEO , Touch International. We Will Answer. What hardware issues do I need to be aware of prior to designing a touch screen device?

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maximizing hardware software selections for advanced touch screen applications

Maximizing Hardware & Software Selections for Advanced Touch Screen Applications

Michael WoolstrumCEO, Touch International

we will answer
We Will Answer
  • What hardware issues do I need to be aware of prior to designing a touch screen device?
  • How do my hardware choices affect software development and system performance?
  • Topics Covered:
    • Touch Product Design Considerations
    • Touch Technology Issues
    • Designing for High-Performance
    • Touch Screen Tail Design
    • Choosing the Right Interface
    • Touch Screen Electronics
    • Tuning, Firmware & Calibration
design considerations
Design Considerations

When designing a unit, consider:

  • Size of display and overall system size
  • How you want touch screen to look and function
  • Application
  • Time to market
  • Environment
  • Industry regulations
  • Cost
display considerations
Display Considerations

Key LCD Considerations

  • LCD lifespan is short – 3 years is common
  • No standard dimensions – 7” is most standard size
  • Select narrower borders for flush finish
  • Design bezel and touch screen for LCD changes
  • Does application require high-bright, high/low temp, high light transmission, or sealable LCD?
  • Is LCDeasily acquired?
  • Cost
touch technology
Touch Technology

Determine Touch Technology

  • Things to consider:
  • Application
  • Environment
  • Availability
  • Cost
  • Also consider
  • Difficulty to manufacture (complexity)
  • Touch input method (finger, pen, glove)
  • How long does touch screen need to last?
touch technology issues
Touch Technology Issues

Projected Capacitive for iPhone Experience

  • Custom designs often very complex
  • Higher cost compared to resistive
  • False touches possible
  • Tuning required
  • Prone to noise interference – may require EMI shielding
  • Multiple input methods dependent upon tuning
  • Sensitive to water
  • Integration can be complex
touch screen integration
Touch Screen Integration

Typical Projected Capacitive Touch Screen Integration

Add back housing to graphic

touch technology issues1
Touch Technology Issues

Resistive for Low Cost

  • Moving parts make resistive not as durable
  • Cover glass is not typically an option
  • Requires input pressure
  • Periodic recalibration
  • Lower optics
  • Requires bezel around touch screen
  • Not the “look” that many expect today
touch technology issues2
Touch Technology Issues

Optical for Large Format

  • Occlusion (line of sight) problems when light path is blocked
  • Subject to interference from other light sources or reflections
  • Thicker bezel needed to hide IR cameras (3mm for 19” screen)
  • Possibility of false touches
  • Susceptible to ghosting
designing for high performance
Designing for High-Performance

Meeting Industry Regulations with Display Enhancements

  • Adding display enhancements to touch can correct many environmental and regulatory issues.
  • Military, Medical, Aerospace Industries – many requirements
    • Aerospace – HIC Compliant, Self Extinguishing, Low Toxicity
    • Military - NVIS compliant, EMI shielding, high-temperature tolerant
    • Medical - NEMA sealable, anti-microbial, shatterproof
display enhancements
Display Enhancements

Military Application Requirements

  • Extreme Outdoor Environments
  • Advanced Sunlight Readability
  • Optimized Video & Light Images
  • NVIS (Night Vision Imaging System) Compliant
tail design
Tail Design
  • Key component to getting touch screen right
  • Consider how much room tail has and placement of it
  • Bending tail can damage communication
  • Chip-on-Flex
  • Only available for projected capacitive
  • Allows for tail to be long and far away from electronics
  • Minimizes noise and interference
  • Entire sensor scrapped if chip needs to be replaced
  • Chip-on-flex is expensive
choosing the interface method
Choosing the Interface Method
  • I2C
  • USB
  • Projected capacitive accepts any interface method
  • Resistive requires USB or RS232
  • Optical usually USB HID
  • Motherboard input type often plays role in choosing interface method.
    • Off-the-shelf unit (lowest cost) limits interface flexibility
    • In-house design (expensive) allows for all options
  • USB HID
  • Serial (RS232)
  • Serial HID
  • USB-UART
touch screen electronics
Touch Screen Electronics

Touch screen performance controlled by controller

  • Converts electronic signal sent from touch sensor to the host PC through a I2C, serialor USB interface in an X/Y format.
  • Two Types
  • PCB (traditional controller board)
  • Chip-on-Flex
touch screen electronics1
Touch Screen Electronics

PCAP Controller Challenges

  • False touch
  • Subject to EMI noise
  • Cost can be very expensive depending on capabilities
  • If slim design/space constraints, then chip-on-flex
  • Custom firmware required for PCAP
touch screen electronics2
Touch Screen Electronics

Resistive Controllers

  • No real challenges with resistive electronics
  • Traditional resistive controller (4, 5, 8-wire) very low cost
  • Multi-touch resistive controllers are expensive
  • Chip-on-flex not an option (also not needed)
  • Easy to integrate or replace

Optical Controllers

  • Any issues with them?
firmware drivers calibration1
Firmware/Drivers/Calibration

Firmware

  • Tells touch screen what kind of touches or input to pay attention to or ignore
  • Can make touches more or less sensitive (application specific)
  • Provides system level EMI shielding

Drivers

  • Mainstream OS drivers loaded on chip
    • Customer must write own drivers for custom OS
firmware drivers calibration2
Firmware/Drivers/Calibration

Drivers

  • Mainstream OS (Windows 7) drivers loaded on chip
    • Android, Linux drivers usually available from chip manufacturer
    • Customer must write own drivers for custom OS

Calibration

  • Projected Capacitive, Optical, MARS - one time calibration
  • Analog Resistive – periodic calibration
what we will cover
What We Will Cover
  • What are the advantages and limitations of software tools used to develop touch applications?
  • How to choose the best software development method for interactive platforms

See word document for software section outline.

operating systems
Operating Systems

Windows 7

  • Industry standard touch screen platform
  • Supports multi-touch
  • Plug and play – does not require additional drivers

Android

  • Supports native multi-touch
  • Additional drivers needed to run touch screen
operating systems1
Operating Systems

Linux

  • Supports native multi-touch
  • Additional drivers needed to run touch screen

iOS/Leopard

  • Supports native multi-touch
  • Additional drivers needed to run touch screen

All operating systems available as embedded O/S