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issue: November 2004 APPLIANCE Magazine

Displays and Control Panels
The New Wave of Displays


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by D. Douglas Graham, contributing editor

Unobtrusive, feature-rich, and aesthetically appealing, the current crop of appliance displays and control panels are built to please the upscale, 21st Century consumer. Today’s designs strike a balance between the purely functional and the “techno-chic,” and display suppliers are working hard to help OEMs achieve both.

Pictured is a membrane switch key panel manufactured by GM Nameplate (Seattle, WA, U.S.) for a GE electric range.

Back in February 2003, Electrolux Home Products North America (Augusta, GA, U.S.) was ready to begin development of its new line of kitchen appliances. The designers wanted the line to include an oven with several cutting-edge features; principal among them was a glass panel, user interface upon which graphics would remain invisible until summoned with the touch of a hand.

“The wall oven was the brain child of our Electrolux colleagues in Rothenberg, Germany,” recalls Bob McCoy, director of Advanced Development and Electronics for Electrolux Home Products North America. “Their R&D had developed a unique, cool-touch door incorporating several panes of glass arranged in a Venturi effect. One of the basic laws of physics is that the faster and harder you blow across the top of a straw, the greater the suction there will be. This was one of the guiding principals behind the oven door design. The heat accumulating between the glass panes gets blown out beyond the door, ensuring a cool touch and protecting all in-built circuitry. The Germans came up with this idea in order to remain consistent with UL standards. The concept works in all phases of operation, including self-cleaning.”

Elegant, Yet Functional

The QTouch™ QT240 from Quantum Research Group (Southampton, UK) is a self-contained, digital charge-transfer sensor chip that can reportedly detect touch of four independent keys through solid, sealed glass, or plastic panels. This capability, coupled with continuous self-calibration and spread-spectrum operation, makes it ideal for human interfaces in consumer electronic products such as monitors and TV controls.

Electrolux’s grand design was to create an appliance that didn’t look or feel like a conventional oven. Instead, it wanted to craft a classy piece of equipment that departed in terms of function and appearance from the kitchen hardware of decades past. The technological hurdles entailed in the project were daunting to say the least, so Electrolux partnered with two leading component makers—TouchSensor Technologies LLC, of Wheaton IL, U.S. and Spitfire Controls Inc. of Barrington, IL, U.S.

“All the companies involved had a conference call in mid-February,” remembers David Muisenga, new business development manager, TouchSensor Technologies LLC. “Electrolux needed a working prototype oven by the first week of April, a window of less than 2 months. TouchSensor is comfortable with short lead times. In fact, our technology and company are founded upon the ability to meet them. The challenge was that Electrolux’s concept required innovation in all areas of the user interface—touch, lighting, and materials—so the bar was set pretty high.”

The core challenge of building a “dead-front” user interface solution is the requirement that little or no light be transmitted during the “off” mode, and the need for optimum light output in the illuminated state, Mr. Muisenga continues. TouchSensor worked in concert with its corporate partner, Gemtron Corporation of Sweetwater, TN, U.S. Using a Gemtron-developed decorative glass substrate, the company merged keyboard, glass panel, and display electronics to nail the look Electrolux requested. The result is a glass panel, touch-user interface that prompts consumers with back-lighted keys during operation, and also offers a clean, elegant look when the appliance is not in use.

“The simplicity of integrating TouchSensor keyboards made the job possible,” Mr. Muisenga says. “TouchSensor user-interface applications employ TouchCells™, which are patented digital-touch switches based upon our TS-100 Field-Effect sensor.”

Mr. Muisenga explains that TouchCells are easily integrated into existing electronics and offer direct replacement of mechanical and membrane switches without the requirement of any signal-processing software. Software-based systems are expensive and time-consuming to develop, which lengthens product launch-cycle and adds costs for OEMs. The components are also UL-recognized and reportedly fail-safe within the challenging environment of cooking applications. According to TouchSensor, this industry-exclusive recognition speeds end-product qualification and attests to the proven reliability of the technology.

Pictured is theSP14N001 liquid crystal display (LCD) from UK-based Hitachi Display Products Group. The 5.1-in display module is said to be ideal for a range of applications, including vending machines and home appliances.

The Role of Controls

Spitfire Controls was Electrolux’s source for the electronic hardware and appliance controls. The company was tasked with creating the support circuitry to take the oven from the blackboard to reality. According to Spitfire’s director of Engineering, Tom Goodrich, the principal challenge was to develop components that would survive the extremely high temperatures generated in baking. There were other barriers to breach as well, principally the overarching task of creating a durable, attractive product as economically as possible.

“Our challenge was to come up with controls capable of coping with elevated ambient temperatures,” Mr. Goodrich says. “The unwritten mission was to make them inexpensively. How do you do that while building-in quality and long-term reliability? Fortunately, we were up for that. Our controls are all microcontroller-based, so there’s a computer involved in everything we do. That took a lot of the guesswork out of the process. We were lucky also in the fact that the project presented a degree of difficulty similar to that of other jobs we’d previously tackled for the industry. The point is we had the experience we needed to do the job right, and get it done on time.”

Some of the ideas Electrolux had in mind, however, did pose design challenges for Spitfire. The manufacturer wanted Spitfire’s controls to drive TouchSensor’s user interface design, a technological request the control maker had not tackled before. Working with TouchSensor Technologies and Electrolux, Spitfire developed a proprietary technology to provide the necessary appliance intelligence.

“In the past, appliance changeover had a life cycle of about 3 years,” Mr. Goodrich says. “Now, the turnover’s about 9 months. We had to create this product with that fact in mind. It had to last.

“The other challenge you face is getting safety agency approval,” he continues. “The agency has certain criteria established about how such things must be done, and we had to put in a system to get past them. ‘Two-step-on, one-step-off’ is UL’s safety requirement for activation. We had to build redundancy in the cancel key to meet this requirement and for the technology to function the way Electrolux wanted it to. In the end, we were able to design the hardware and software so that the backlight remained visible for whatever time was required to support one-step-off capability.”

Building a Better Component

The Atrezzi™ blender from Jenn-Air incorporates Qtouch 9 key technology from Quantum Research Group (Southampton, UK). According to the supplier, Qtouch provides appliance makers the ability to achieve an attractive interface at a cost-effective price.

With the 21st Century well underway, display and control designers are faced with a new menu of design criteria and an old set of challenges. First and foremost, they must produce a quality product consistent with the expectations of increasingly discriminating consumers. Today’s appliance buyer no longer shops solely with function in mind. He or she also wants convenience, practicality, and elegance. As the aesthetic appeal of appliances has become more prevalent, manufacturers have been focusing more attention on user interface. The increasing interest among consumers in graphic color and brightness has also encouraged a more extensive use of pixel-based graphical displays and more elaborate lighting effects.

“Interfaces have changed their function in the appliance market,” says George East, product line manager for the Exotic Products division of Quantum Research Group in Southampton, UK. “Once strictly necessary devices for product operation, they now add unique selling benefits. Along with being intuitive and practical, they are often the reason you would or would not choose one product over another. In a market where competition is fierce and products are comparable in functionality, it’s imperative that your product has the edge it needs to spark the buying impulse. When my wife, for example, chooses a product, more often than not she’s more interested in its ‘look’ than in its specifications.”

Buyers are also more purchase-savvy now, thanks to the growth of consumer culture and the easy access of product information via the media and the Internet. This has helped put retailers at sword-point with one another in an appliance marketplace increasingly characterized by ferocious competition. Add to that the steady flow of low-priced products coming from all parts of the world, and you have a situation that cries out for cost cutting.

Like the appliance producers with whom they do business, display and control suppliers are under constant pressure to reduce costs. They accomplish this in a number of ways; one being the well-known tactic of “just-in-time” (JIT) manufacturing whereby product is supplied on an “as-needed” basis. Overall cost reduction of the product itself is another means to the same end. Through strategies such as lean manufacturing and supply-base differentiation, both appliance producers and their suppliers reduce the cost of parts and maintain the health and quality of the appliance industry supply chain.

“Ultimately, appliance producers are looking to streamline the process for overall cost effectiveness,” explains Glenn M. Gruber, product line manager of Parlex, a subsidiary of Poly-Flex Circuits Inc. of Cranston, RI, U.S. “By working with quality suppliers in the initial design phase, you reduce the total expenditure by ensuring a successful product upfront and save having to respond to field failures down the road.”

Some suppliers are also teaming up with each other in another effort to help keep costs down and quality up. A leading maker of flexible circuits using polymer thick film technology, Parlex works closely with FLEXcon, a manufacturer of pressure sensitive film and adhesive solutions located in Spencer, MA, U.S. FLEXcon’s SWITCHmark® is a line of high-performance spacer products and laminating adhesives for membrane switch and interface technologies used in the design of appliance displays and components.

“Two major considerations to take into account when designing a control or display panel are interface and ergonomics,” Mr. Gruber says. “While the end users’ interaction with an appliance sits within the design aspects of the interface, the actual complexity of the appliance is hidden. Whether the interaction is guided aesthetically through a membrane switch integrating tactile or non-tactile switches, LEDs, and seven-segment indication displays, for example, manufacturers are then challenged with pulling this exterior design philosophy together with the implementation of the technology behind that surface. This ultimately is what assures an easy and pleasing experience for the consumer.”

Appliances are as much a decoration aspect to the consumer as they are functional, Mr. Gruber suggests. As family lifestyles move back into the kitchen, interest in their exterior features is growing. At the same time, appliances must still function efficiently and be programmed to perform and differentiate a broad range of tasks. Mr. Gruber says that by working with suppliers like FLEXcon, Parlex has been able to build better interfaces and make certain that mission-critical functions are unobtrusively incorporated into the product.

“There’s been a trend of early involvement of suppliers/partners in the new product development phase,” adds Dr. Jens Hoche, general manager of White Goods Electronics, Schott Home Tech North America (Louisville, KY, U.S.). “More and more the relationship is being defined as partner-to-partner rather than as supplier-to-customer. This trend has been especially noteworthy in the production of high- to mid-line and high-end appliances. As these products become more electronically-sophisticated, suppliers and customers develop them jointly.”

The appliance industry is moving forward with more interfaces such as LCD displays, new and different activation technologies, and in-mold decorating, says Nick Cottrell, senior engineer at Whirlpool Corporation of Benton Harbor, MI, U.S. Graphical interface is becoming a component of the unit itself, with displays seamlessly transitioning the walls and doors of the appliance. The user doesn’t see the intrusion because it’s been rendered invisible.

“One of the concepts driving this development is ‘cleanability,’” Mr. Cottrell explains. “The lines and butt lines created when multiple parts are thrown together on an appliance become magnets for dirt and dust. There’s also the hunger among consumers and industry for the new and different. Everyone is getting tired of the white box, and the industry is pushing hard to get new concepts into the marketplace. Two factors seem to be motivating this phenomena—the pressure of overseas competition and the desire on the part of appliance makers to increase market share.”

User experience must also be a primary consideration of appliance control panel design, says Stephen Caldwell, director of the Home Appliance Solutions Group of Microchip Technology Inc., a Chandler AZ, U.S.-based control provider. The control panel acts as liaison between user and machine, Mr. Caldwell explains. Via this conduit, the user conveys his or her intentions to the appliance, and it responds with feedback. The conversation should not be muddled by miscommunication. It should instead be clear, pleasant, simple, fast, and accurate.

“Aesthetics are critical as well,” he continues. “Nowadays consumers want to integrate their appliances into their home décor in a way that improves the environment, and like everything else about the appliance, the control panel should enhance the user experience. It should provide him or her with a warm welcome.”

The Changing Face of Interface Technology

Control panel technologies range from the more traditional membrane style interfaces to the resistive and capacitive-style touch screens. As Mr. East of Quantum Research Group explains, membranes are cost-effective, but have a “mushy” feel when operated. They also become dirty quite easily due to the ridges between buttons, and they often lack aesthetic appeal. For this reason, many manufactures opt for touch screens, which allow the designer to create a smooth touch panel. Because of the nature of capacitive technology, switches can be placed behind glass, plastic, or any other non-metallic material. This provides users with a very firm substance with which to interface; one that will maintain its feel and looks throughout its working life.

“Interface screens/displays are available in two forms—resistive and capacitive,” Mr. East explains. “Again, one form is traditionally used over the other due to cost. Resistive has been greatly used in the past, as it has proven a more cost-effective solution. The drawback to resistive screens and displays is the fact that they are fairly easily damaged and to be operated, force must be applied to the screen to bring the two resistive layers together.”

Capacitive technology has always been more costly than resistive due to its advanced electronic processing, he continues. There are now a number of methods for creating capacitive touch-screen technology that are very application/environment specific. Because little or no force is required for operation, a capacitive touch-screen can be created from glass and other durable products, lending greater life expectancy to the product.

According to Brad Root, president of GM Nameplate in Seattle, WA, U.S., control panels have evolved to the point where nearly all are membrane. “Membrane switch panels offer space, reliability, and cost advantages over knobs and dials,” he explains. “You also get greater cleanability with membrane switches, but the biggest advantage they offer is probably in the area of reliability. Every time you touch a mechanical switch, you induce wear. Not so with membranes. They’re good for a million actuations or more.”

Most of the materials used to create membrane switches for the appliance industry are polycarbonate-based, Mr. Root says. Polycarbonate is probably the ideal medium for appliance use because actuation is a very short distance, and very little flex is required. Polycarbonate also doesn’t get “milky” with use, Mr. Root says, which is a good thing because when deployed on a kitchen appliance, it will see a lot of service.

“There are a number of advances and developments on the horizon for the interface industry,” notes Mr. East of Quantum Research Group. “Take a look at the Apple iPod and the method used on it for scrolling through menus and tracks. This form of interface can be used for a number of solutions in the appliance industry, from setting selection on washing machines and dishwashers to speed controls for blenders. These slider-style products come in various guises from linear versions to rotary (like the iPod). Linear sliders are already being used in the appliance market for heat controls and cookers.”

According to Cliff Ortmeyer, a market development engineer for STMicroelectronics (Geneva, Switzerland), leading display technologies for appliance applications include liquid crystal displays (LCDs) and vacuum florescent displays (VFDs). There is also a growing use of organic light emitting diodes (OLEDs). “The standard display type is the light emitting diode (LED), whose primary advantages include cost, ease of implementation, and light resistance,” he says. “The advantage of LCDs is their ability to offer a lower-cost, full-featured graphical display. However, constant brightness and operating temperature range can limit LCDs, depending on the end product they’re going into.”

OLEDs, on the other hand, offer a range of possibilities but are cost-prohibitive in many applications, Mr. Ortmeyer continues. “VFDs come with drawbacks as well, as they have more complex power supply requirements than many other solutions,” he says. “Based on that, it seems to me that LEDs and LCDs will continue to enjoy their current popularity mainly because of the cost advantages they offer verses the other technologies.”

At the end of the day, OEMs realize that the best technology is the one that best serves the consumer. “Control panels have begun to incorporate many more possibilities for the consumer, who now has a host of options available to him,” notes Ken Crass, appliance business manager of Serigraph in West Bend, WI, U.S. “This increase in options requires that a lot of information be provided, sometimes in a very limited area. This requires switches to be more compact, as well as the use of displays to provide feedback to the customer.”

All in all, Mr. Crass says the interface business is more challenging than it used to be. “Appliance makers are demanding more for less,” he notes. “They are leaning more toward in-molded bezels to help make the panel sleek and seamless, while eliminating the need for additional secondary options. It’s the same with consumers. They want a bigger bang for their buck in the way of style and function, and it’s incumbent on our industry to give it to them.”

Suppliers mentioned in this article:
TouchSensor Technologies LLC
Quantum Research Group Ltd.
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