Touchscreen Integration and Display Enhancements
As an embedded systems integrator, BVM understand the importance of integrating other embedded devices such as TFT displays with touchscreens so we can offer our customers interactive solutions. This includes cable design for data interfacing and backlighting through to bonding of specific touchscreen technologies to ensure your application interacts in the way you need it to.
Touchscreens have been around since the days of the CRT, but have really taken off with the advent of smartphones & tablet PC’s and have overcome problems such as ‘small buttons’ deployed on devices prior to the touchscreen technologies of today.
Why are touchscreens used on an ever-increasing basis?
- Easy and Intuitive to use
- Easy cleaning and maintenance
- Increased functionality – dual Touch / Multi-Touch allowing for pinch, zoom, rotate, slide…etc
- Simpler user interface
- Lower costs – removal of buttons & protective cover glass screens
- Improved flexibility for upgrade and customisation
- Real-time interaction
- Aesthetically better-looking products; ‘zero bezel’ (completely flat) look
We offer a range of TFT/LCD customizations, including:
- Customised TFT/LCD module design
- Touchscreen and cover glass customisation
- Custom firmware
- Custom controller design
For those looking for more comprehensive customisation options, we also offer finished monitor customisation services. This can include:
- Standard off the shelf product customisation:
- Custom bezel colours
- Custom logo
- Custom open frame chassis design
- Complete custom monitor design
In general, there are two main use touch technologies deployed in embedded / industrial applications; that of Resistive and Projective Capacitive (pCAP). However, there are others such as capacitive, infrared, surface and acoustic wave (SAW) which are more application specific.
Resistive Touchscreen Technology
Restive touchscreen integration generally stems across display sizes from 1” through to 24” (although above 20” is rare). There are many manufacturing sources of touch screen controllers on the market which makes them low in cost because of their ‘commodity’ nature.
They will operate via finger or stylus input and are generally regarded as low cost/low power touch type technologies – making them widely available. They are easily sealable to IP65 ingress protection and are resistant to a wide a variety of screen contaminants and consequently are easily cleanable via the use of mild detergents and fluids.
The most common deployed restive technologies are 4-wire (low cost, shorter life), being common in mobile devices and 5-wire (higher cost, longer life) – more common in stationary devices. The most common construction is film (PET) + glass – but other construction technologies available are film + film for increased flexibilities from the touchscreen – and glass + glass for durability (used in the automotive industries). Common enhancements include application of anti-glare/anti-reflective (AR/AG) coatings to provide for higher transmissivity.
Resistive Touchscreen Operating Principle
Resistive touchscreens are built around two parallel layers of conductive ITO with a top layer made of flexible PET film. When pressed, it bends and touches the bottom ITO layer which causes a change of resistance which is used by the controller to determine the location of the point of touch.
Projective Capacitive Touchscreens
Projective touchscreens are extremely durable (because of the use of protected sensors) and provide high optical quality via their ITO. They provide for an unlimited multitouch experience (compared to that of single touch input of resistive touchscreens) and are unaffected by debris or contamination coming into contact with the touchscreen. Aesthetically, they enable a ‘zero bezel’ look industrial design (edge to edge glass look) and work with curved substrates (on PET).
In today’s ‘tech-products’, they’re now frequently deployed in consumer devices such as smartphones, tablet PC’s, Netbooks, Notebooks – and interactive retail digital signage.
However, they are becoming increasingly popular also in more & more industrial design products which is increasingly pushing their market share usage up – and consequently their commercial pricing down.
Projective Capacitive (pCAP) Touchscreen Operating Principle
Built around two parallel layers of conductive ITO, the pattern on the ITO layers forms a grid of capacitance creating an electric field. When the user finger approaches touch, it couples with the electric fields, which changes the capacitance of several capacitors in the vicinity of the finger and an algorithm converts the changes in capacitance to X and Y positions.
Touchscreen Bonding Options
Strip Bonding – Resistive Touch Screens
Strip bonding the process where strips of double-sided gasket are placed on the bezel of a display to create a frame. The touch screen is then aligned on the display to form the final assembly and facilitate a quick and easy way to facilitate touch screen bonding – whilst maintaining clean room standards.
Depending on the needs and budget of the application, we offer two options for strip bonding. For a more budget-friendly option, we use roll gasket that is applied in straight strips with a seam on the corners. For a high-end requirement, we offer die-cut double-sided sheet gasket for a seamless border.
Optical Bonding – Projective Capacitive (pCAP) Touchscreens
Optical bonding is a process that involves applying a silicone layer between the TFT LCD and touch glass to eliminate any gaps and improve the overall optical & visual performance of the display. This enhances daylight readability and eliminates the need to look at other more expensive technologies such as transflective displays and also improves system robustness for protection against shock and vibration – and the prevention of display ‘fogging’ and parallax.
Other Bonding Processes
In addition to strip and optical bonding, BVM also have extensive experience in bonding glass and filters, including ITO and EMC mesh filter glass. We are able to provide recommendations and guidance on various types of glass, as well as options for different thicknesses, thermal or chemical toughening, surface treatments (AG/AR), and printing (organic/ceramic).
BVM Projective Touchscreen Customisation Services
BVM have many years of experience when it comes to designing for the integration of projective capacitive touchscreens and are experienced in the challenges faced during the integration process.
BVM will design to ensure noise sensitivities are observed at all times & stray capacitances are kept to a minimum. We’ll keep ITO resistance of each sensing strip as low as possible to improve SNR (signal to noise ratio) – keeping metal connection wires to one side of the panel to improve linearity and make stray capacitance easier to handle – and we’ll also ensure the proper thickness of cover glass is used for the application at hand.
BVM also offer a range of other supporting
touchscreen integration and display enhancement services, including :
- Customisation of firmware for touchscreen controllers
- Custom cable design
- Custom power supply design
- Custom chassis design
- Application of corporate colouring (RAL or Pantone) for bezel surrounds and screen printing for application of logos and borders on the cover glass
Display Enhancement Services
To complement this range, we also offer display enhancement services to provide you with exactly what you need. Here’s a selection of our services :-
- LVDS and backlight cable manufacture
- Application of anti-glare/anti reflective coatings
- Touch screen integration – pCAP, resistive….etc
- Optical bonding for sunlight readability and display robustness
- LED backlight enhancement services
- FPC tail positioning
We like to make life easier ….
Our technical & commercial team members will always provide you with valuable but impartial advice around the products and services that BVM provide. With their collective backgrounds, they’ll provide you with the benefit of their knowledge and experiences when & where you need it. We’ll always help you in the first instance and get back to you when additional information is required.