Integrating Light Guide Film Backlighting

Integrating Light Guide Film Backlighting

CSI Keyboards is a global leader in membrane switch backlighting and interface backlighting technology. CSI has over 35 years of experiencing backlighting user interfaces, from as simple as backlighting a logo to backlighting individual keys to backlighting the entire interface surface. CSI’s backlit products include: backlit human machine interfaces, backlit membrane switches, backlit elastomeric keypads and backlit panels or signage.

Why Light Guide Film?

CSI integrates Light Guide Film (or LGF) into many of our backlit keypad interfaces and membrane switches. Light Guide Film is a thin film that will direct light produced by side-firing, or right-angle, LEDs across the area that needs to be backlit. The film is placed directly below the graphic overlay and above the circuit layer so that the light will not be obstructed by any circuit traces or tactile components. This film can be cut into any pattern or shape within your switch. Multiple LGF films can also be used within one application to provide discrete backlighting to different graphic features. Different colored LEDs can be used to achieve unique lighting effects or white LEDs can be used to light different printed graphics on the overlay.

It is critical that the LEDs are properly placed on the circuit in order to adequately light the intended area. CSI will carefully evaluate the placement of these LEDs to ensure adequate light distribution and to avoid any hot spots.  

There was a time when the only way to backlight interfaces was to use standalone LEDs or EL panels. The problem with using LEDs without LGF is the creation of hot spots and uneven dispersion of light. EL panels are not only expensive, but they are not as bright as today’s LEDs. LGF is extremely thin so it can be incorporated into membrane switches that can’t exceed a certain thickness.  It can provide even backlighting across large and small areas, and for applications where the light remains on while the switch is powered.

Backlighting Membrane Switches

Backlighting Membrane Switches

Backlit membrane keypads for interface








Membrane Switch Backlighting

CSI Keyboards has been backlighting membrane switches, HMIs and user interfaces for over thirty five years. We’ve used backlighting techniques from the simplest LED membrane switch using a single colored LED indicator with a transparent smoked LED window (to hide LED from surface), to the most complicated multi-colored membrane keypad switch assembly. We can bring your product to life and make it truly stand out from your competition. Typical backlit designs include: backlighting keys, nomenclature, logos, perimeters, indicators, or the entire keypad.

Rubber Switch Backlighting

When it comes to elastomeric rubber keypad backlighting, CSI has the expertise to utilize and take advantage of molded silicone rubber which is an excellent conductor of light. CSI Keyboards utilizes translucent rubber, laser etching, light piping technology as some of our many techniques.

Backlighting Solutions

LEDs: LEDs are the most popular and economical method for keyboard backlighting. LEDs are most commonly used to backlight keys, icons and symbols. LEDs are also typically used as indicator lights. A combination of LEDs, Light Guide Film and proprietary CSI backlighting methods can be designed to backlight the entire surface of a user interface.

Light Guide Film (LGF): LGF is designed to evenly distribute light from top or side firing LEDs, providing bright, uniformed illumination. It also reduces the amount of LEDs needed, saving power consumption. More on light guide film technology below. CSI Keyboards uses proprietary techniques to design the light guide film so it is optimized for light redirection and reflection giving the customer the brightest possible backlighting solution. Light guide film dots are also designed and implemented which allow for the optimization of light distribution to obtain maximum brightness and uniformity. Common problems that many of our competitors face are light leakage and hot spots. CSI’s backlighting designs prevent any light leakage and hot spots from occurring, and also result in much brighter light guide film and interface.

Electroluminescence (EL): EL is applied on a very thin layer between the graphic overlay and the circuit. EL uses a printable ink deposit to illuminate the switch and provide a uniformed illumination.

Fiber Optics: Fiber Optics provide a flexible back lighting layer that can be incorporated between the graphic overlay and the circuit layer allowing the entire surface area of the membrane switch to be evenly backlit.

MD&M BIOMEDevice Tradeshow Recap

MD&M BIOMEDevice Tradeshow Recap

CSI Keyboards Tradeshow

Considered to be New England’s biggest medtech showcase, the BIOMEDevice Boston once again did not disappoint. Whether your focus is new materials, intelligent sensors, testing solutions, components, or anything else in the medtech arena, source cutting-edge products and services in a time-saving format with more than 450 solution providers across the full spectrum of medtech manufacturing.

The 2018 MD&M BIOMEDevice Show print show at the Boston Convention & Exhibition Center was full of inspiration. Boston, MA was bustling with manufacturers, medical device companies, and design houses from near and far. This was the fourth year CSI Keyboards has exhibited at the Conference. It has proven to be an excellent venue for meeting engineers from not only all around the country, but the whole world. CSI is able to showcase our wide range of products including membrane switches, rubber keypads, touch screen interfaces, and our many other user interface and HMI solutions. Being able to exhibit samples of our products allows engineers, buyers or even just the casual or curious passerby to “play” with our products hands-on. It was also great seeing many of our existing customers stop by our booth to chat and learn about some of new products and capabilities. Until next year, Boston!

Polyurethane Coating for Rubber Keypads

Polyurethane (PU) Coating for Rubber Keypads

Polyurethane (or PU) is a protective overcoat applied to rubber keypads. This clear coating provides wear resistance for very high use applications or products that are used in harsh environments. Adding the polyurethane coating to rubber keypads ruggedizes the keypad, increases abrasion resistance, adds UV resistance and prolongs the longevity of the rubber. It provides superior resistance to corrosion andchemical exposure. This particular coating is also a cost effective solution. 

PU coatings protect rubber keypads from oils, dirt, and contamination. The polyurethane may be applied in a glossy or matte finish, to meet the aesthetic requirements of the rubber keypad. The polyurethane coating is deposited on the top surface of the keypad over the printing. Polyurethane coatings are used across all industries to improve the appearance and lifespan of the materials.

CSI Keyboards, membrane keypads, elastomer keypads, complete turnkey assemblies, integrated touch screen solutions, capacities switches, plastic injection molding, printed circuit board assemblies, display solutions, backlighting solutions, environmental sealed HMI solutions, Peabody MA

Parylene Coating for Rubber Keypads

Parylene Coating for Rubber Keypads

Parylene coating is a vacuum deposited coating that improves the longevity of silicone keypad artwork by up to ten times. Unlike polyurethane coating, Parylene coating is applied as a gas. The application process allows the parylene polymers to penetrate tight areas on the part, providing a uniform coating on all surfaces. 

Parylene’s thin, transparent and flexible characteristics enhance the performance of rubber and elastomer components by protecting surfaces and modifying surface properties. These improvements are made without degrading the functional performance of the part. Parylene yields a truly conformal coated part with a consistent thickness on both flat surfaces and around the internal dimensions of openings and features. The parylene coating also tends to improve the feel of the surface by removing the elastomer tack while protecting the keyboard against dirt and oils, and also protecting the printed nomenclature.

Benefits of Parylene Coating

• Dry film lubricity

• Pinhole-free

• Thoroughly conformal

• High surface bond strength

• Thickness consistency

• Chemical resistance

• Solvent resistance

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