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Interconnection & Switch Technology

Capacitive switching helps develop “Thin Film” backlighting technology

Vince Light, Technical Director of Stadium IGT, reviews the latest developments in LED backlighting technology

With the rapid rise in the use of smart- phones, tablets and PDA’s in their home and business lives users have become very familiar with capacitive switching technologies and are now expecting to have the same man-machine interface (MMI) available on industrial control and instrumentation. Integrating capacitive switching into industrial control offers designers many benefits including improved product ergonomics and aesthetics, increased functionality, lower component count, simplified manufacturing and increased reliability. However there are a number of practical issues that have to be considered before moving away from discreet switching or membrane type keypads including ruggedizing and illumination. Most users of modern smart phones and tablets will be only too aware of their frailties! The latest developments in capacitive switching technologies allow them to be hermetically sealed and function behind a glass or polycarbonate overlay of up to 13mm. This addresses the more extreme MMI application areas and other applications where waterproofing is required or vandalism is a potential hazard including public areas such as street mounted information terminals at bus stops etc., help-points for commuters and tourists, ticket machines, self-service tills,

Economical PS Series switches now available in SPDT versions

C&K Components has developed a latching pushbutton switch with a full 4.5 mm of travel. The economical PS Series switches feature latching contacts and are designed to work in conjunction with standard male commercial pin and socket connectors, 1.57 mm sq (0.062” sq) pins with 4.05 mm (0.16”) spacing. The single pull double throw (SPDT) PS Series pushbutton switch changes electrical state on the down stroke of the plunger and delivers “on-off” or “on-on” functionality.

The PS Series switches have been extensively designed into auto interior

32 December 2013/January 2014

lighting, computer, appliance and flashlight applications.

The RoHS-compliant PS Series switch has a mechanical operating life of 20K cycles, and features a contact rating of 1A @ 14VDC, a contact resistance of 100Mohms (maximum), an insulation resistance of 100Mohms (minimum), and a dielectric strength of 500VAC (minimum). The switch’s operating temperature range is from -20°C to 70°C.

C&K Components |

Components in Electronics

vending machines and rugged industrial applications including control systems and medical and industrial instrumentation. Status indication for discrete and membrane type MMI is largely an LED placed adjacent to a switch or included in the actuating button. This may be suitable for very simple control functions but the introduction of capacitive switching screens and their ability to allow control functions to be re-designated during use and show graphic pictograms call for a much more sophisticated display technology. Stadium IGT has developed an innovative method of combining the benefits of capacitive switching with multi- colour area-specific backlighting. Historically, illuminating capacitive switches has caused problems for designers but by using thin film light guides and remote LED light sources, the two technologies can be successfully integrated into a single efficient design offering fewer layers and components.

This patented “Thin-Film” backlighting technology provides bright, even illumination with no hot spots adjacent to the light source, segmented illumination providing partially lit areas with no light “bleed” between segments and integrated Illuminated icons and logos. The capacitive sense pads and LEDs are manufactured on a single PCB which can include the LED

encoding and driving components.

This high level of integration offers lower manufacturing costs and increased reliability as there are no moving parts - even membrane key types are mechanical. The integration of

capacitive-switch panel and backlighting reduces cost and simplifies integration and test as it is supplied as “single box” solution.

Complete “Thin-Film” backlit panels may be as simple illuminated displays or include complex ideograms to graphically indicate system status and in addition to capacitive

switches incorporate slider controls, joysticks, tracker balls and displays. Offering an ultra-thin Z-axis (thickness) of typically 1.2 - 2mm “Thin-Film” backlighting technology can be curved to meet end product functionality or aesthetics and for high-volume applications may be injection moulded to further reduce costs. Operating from a low voltage DC power supply removes any high voltage requirement that alternative video monitor based systems may require and allows the use of an N+1 redundant

power source for safety critical installations.

“Thin-Film” LED backlighting technology also offers colour-changing LEDs, “secret until lit” signs and high impact product branding options which can differentiate the end products from competitors and is the perfect illumination method to complement the growing use of capacitive switching as the preferred man-machine interface.

Stadium IGT |

FCI augments Mezzostak Mezzanine connectors with 80 and 90 position offerings

FCI has strengthened the portfolio of its MezzoStak Mezzanine connectors with the addition of 80 and 90 position offerings. These new variations’ stub-less contact interface supports PCIeGen2 compatibility and supports high speed performance of up to 5Gb. As a result these connectors can support communications and networking applications with higher signal transmission.

The MezzoStak Mezzanine connectors

feature an innovative hermaphroditic “mate-to-itself” design that reduces product mix and simplifies connector selection, documentation and component maintenance. This allows engineers to significantly reduce cost and time spent in the design and maintenance phase.

The four guidance “scoops” integrated in their design permit easy mating and precise connections even when mis- aligned. Their polarisation feature also eliminates the chance of mis-mating and prevents errors in Printed Circuit Board (PCB) placement.

This family of 0.5mm fine pitched, high density mezzanine connectors is also compact and allows design engineers to save real estate on the PCB. This space- optimizing feature allows design engineers to use the freed PCB space to integrate more functions or boost existing performance, while still retaining an overall compact design.


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