Transparent conductive CNB™ Films and touch sensors for flat, flexible and formable touch devices
Canatu produces transparent conductive CNB™ Films and touch sensors for touch screens and touch sensitive surfaces. The main touch application is Projected Capacitive matrix touch, however CNB Films can be applied also in other touch devices such as resistive touch sensors and touch buttons and sliders. CNB Films enable sensor flexibility and 3D shapes while resulting in higher display contrast than the currently widely used transparent conductive material Indium Tin Oxide (ITO). CNB Films can replace ITO which contains the toxic and increasingly scarce rare metal, indium.
Canatu sells its CNB™ Films directly to high volume touch sensor and module vendors and display manufacturers. The touch sensor, module or display manufacturer will deposit auxiliary film layers such as patterned metallic conductor traces, pattern the CNB Films for customized pattern defined by the touch controller vendor, laminate the CNB sensor sheets to each other and touch window, and attach the flex circuit with controller IC to make a full touch module.
Key benefits of CNB Films and touch sensors:
Flexible and 3D formed touch devices
Canatu’s products enable exciting touch features on flexible and 3D shaped devices with a simple device structure that results in thin form factor and cost benefits. CNB™ films have passed bendability lifetime tests at less than 2 mm radius. Furthermore, CNB™ films are thermoformable, maintaining conductivity even after 100% stretching.
Canatu has developed a dome-shaped 3D formed multi-touch sensor. The sensor surface is spherical, and it has been created by thermoforming a flat CNB™ sensor on plastic substrate. The sensor can detect 10 simultaneous touches and the report rate is 12 ms. Canatu has been able to develop the sensor patterns to be totally invisible and light transmission through the active CNB sensor layers is record high 97%. For the first time, a 3D shaped multi-touch sensor has such a high transmission and no visible patterns. This is an important milestone in enabling 3D shaped touch products in applications such as portable electronics, wearable devices, household equipment, consumer appliances, and automotive interior surfaces.
Canatu has also developed flexible touch sensors with world-record bendability, to be applied in flexible and foldable consumer electronics products.
Improves touch display contrast
Display images of emitting displays such as backlit LCDs and OLEDs and some reflective displays such as e-Paper get washed out under bright ambient illumination outdoors, in vehicles, or in bright indoor locations. The effect is due to unwanted reflections in the displays, and is worsened by using a touch panel that reflects light, such as industry-standard Projected Capacitive touch using Indium Tin Oxide (ITO) transparent conducting films. Various approaches have been used by the industry to solve the issue, such as employing moth-eye filters, circular polarizers or color filters, or using other touch methods than ProCap, e.g. IR, SAW, or optical touch. These approaches typically add costly new components to the display, reduce available display brightness, add complexity, increase the use of scarce device real estate, or result in compromised touch performance.
The use of CNB™ film based touch sensors significantly reduces reflections due to ambient light, and therefore increases contrast over ITO based touch sensors. Canatu built a laptop product comparing an LCD touch display contrast with an One-Glass-Solution ITO touch sensor to one with CNB™ based GFF (Glass-Film-Film) touch sensor. The reflectance from the ITO OGS laptop was 50% higher than from CNB™ based laptop, resulting in 30% better contrast in CNB™ based laptop in a bright office on a sunny day (2000 lux). This makes a clear difference in display readability. The effect is shown to be due to the very small reflections in the CNB film stack, attributed to the naturally good optical matching of the CNB materials to the PET, and almost no haze. No special index matching layers are needed in the CNB sensor stack, and still the reflectivity and haze are lower and contrast clearly better than in the equivalent ITO stack.
Canatu’s CNB™ film based touch sensors enhance display contrast without additional costly contrast enhancement components. Further, the high display contrast directly translates to better visual user experience particularly in bright ambient conditions such as bright offices, vehicles, and outdoors.
Canatu’s Generation 5 CNB™ films have the highest transmission of any carbon nanomaterials, with 96% transmission at 150 ohms/square sheet resistivity, and almost perfect color neutrality. Therefore, CNB™ films result in touch displays with crisp images, vivid colors and non-visible touch sensor patterns.
Increased battery lifetime
Increased battery lifetime is on top the consumers’ list of improvements requested for portable devices such as mobile phones and tablets. The low reflectivity and haze of CNB™ films enhances contrast and outdoor readability of touch displays. Therefore, the users can turn down the backlight to save power and extend battery life, without compromising the display contrast. A customer case showed 17% increase in battery life of a tablet with touch sensing enabled by high contrast CNB™ films, compared to an existing product with ITO sensor.
CNB™ films are manufactured by Roll-to-Roll processing. Carbon NanoBud® material is created from abundant carbon gases by aerosol synthesis and the CNB™ films are deposited by an atmospheric pressure process, Direct Dry Printing®. This simple, entirely dry manufacturing process ensures cost efficiency and reduction of layers in the supply chain.
The natural index matching of CNB™ films will provide simplification of touch sensor stack due to no need for anti-reflective or index-matching layers as in high-quality ITO stacks. The result is reduction of system cost.
Fast turnaround in production and development
CNB™ films are supplied in rolls or sheets that can be stocked by the touch sensor manufacturer. CNB™ film fine patterning for sensors is recommended to be made by laser ablation. In laser ablation the CAD patterns can readily be changed in a matter of minutes during hectic product development projects. During product ramp-up or in case of demand increase, laser capacity can easily be added step-wise as opposed to bulky and high-CapEx wet processing lines.
Unlike in some other materials, the CNB touch patterns are invisible. The CNB™ touch sensor design requires no pattern tuning to display cell pattern (no aliasing or Moiré), resulting in faster development and changes.
Green carbon technology
CNB™ film manufacturing process does not involve toxic or caustic chemicals. Furthermore, being single-walled carbon nanomaterial, Carbon NanoBud® material does not pose health hazards