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issue: November 2005 APPLIANCE Magazine

Control Panels and Displays
Aesthetics to the Fore

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by David Simpson, Contributing Editor

Control panels and displays, some with touch capabilities, are being better integrated into an appliances total look while conveying more information to and from the user.

Touch controls usually require a user to physically touch a surface, but this is not always necessary. For example, Freescale Semiconductor (Austin, Texas, U.S.) has introduced a 3-D imaging chip to permit reliable detection of a field up to a 1/2 m from the control. As Freescale explains it, many objects encountered in daily life can affect an electric field (e-field). The charge can be sensed and 3-D imaged, showing how one object relates to another object or to its environment. Information gleaned from e-field sensing and imaging can be used to trigger functions such as turning switches on or off, disabling features or setting off alarms to indicate dangerous situations. An e-field imaging chip, the MC33794, together with electrodes and a microcontroller, can help embedded systems designers readily implement 3-D sensing and imaging applications. A conventional application might be a touch keypad with electronics below a glass-ceramic cooktop. A slider function could cost-effectively be included since the technology allows fine resolution with just two electrodes. Another application might embed a few electrodes in the body of a hair dryer, which could turn on when picked up and turn off when set down. A few more electrodes would allow the user to control the temperature or speed by touching a defined location on the dryers barrel. Other applications that could be simple to implement include liquid level detection, spill detection or moisture sensing. Ranges with flat tops could be programmed so that, when liquid boils over, the heat will be automatically reduced or turned off. "Electrodes can be designed-in pretty much anywhere, explains Brad Stewart, principal applications engineer. They will have flexible, continuous voltage output. Once you define the electrode pattern, the microcontroller can make the decisions. This can be quite a cost-effective solution.

Electromechanical controls have provided reliable service in appliances for decades, but today the growth is in electronic controls. Suppliers extol virtues such as accuracy, an easy-to-clean flat surface, plus ever-more powerful, more cost-effective microprocessors. Electronics allow appliances to connect to a growing variety of sensors or to a home network.

Electronically controlled appliances are using more sophisticated displays, some with full-motion graphics and touch controls. The displays improve communication between human and machine. How much longer will the dishwasher run? What is the room temperature and humidity? Which settings have I picked? How do I cook a roast? The information conveyed on a display can be as detailed as desired by an appliance engineer.

Electronic controls and displays also lend themselves to creating a pleasing appliance appearance. Aesthetics now play a large role in the design of appliance control panels and displays, points out Stephen Caldwell, director, home appliance group, Microchip Technology Inc. (Chandler, Arizona, U.S.). Appliances are trending away from the white box look. Industrial designers are now stressing streamlined, simple, modern appliances that are aesthetically pleasing. Designers are learning from technology leaders like Apple and Sony that consumers desire individuality. This desire leads designers to use non-standard materials and appearance, such as colored and clear plastics, flexible printed circuit boards (PCBs), and glass panels. The panel display must support different colors, curves, twists, and odd shapes.

With advancements in technology and the manufacturing process, surface mount device (SMD) LED displays have taken a dynamic role in the market. Kingbright Corporation (City of Industry, California, U.S.) says it enhanced SMD LED display technology by developing a 0.4-inch character height blue SMD LED display that offers more size and color flexibility, higher reliability, improved efficiency, and significant cost reduction to the production phase.

High Tech, High Touch

Alice Moran, marketing manager, 3M Touch Systems, 3M Optical Systems Division (Methuen, Massachusetts, U.S.), sees a growing role for touch displays in white goods. Appliance producers want to differentiate their models, and consumers are willing to pay for high value options such as touch screens, she says. Touch screens are especially useful where there are many levels of menu options, and users like that the screens present a sleek, smooth surface and are easy to clean.

One unusual application involving 3M Touch Systems is the TMIO Inc. (Cleveland, Ohio, U.S.) Intelligent Oven. This uses a 3M MicroTouch (TM) ClearTek (TM) 6.5-inch capacitive touch screen. The ovens give owners real-time remote commanding control with a cell phone, computer or PDA, allowing consumers to start cooking dinner from the office or on the go. The touch screen is able to meet the high-temperature requirements, while TMIO engineers have been able to keep the electronics cooler than most oven designs require. The transparent overcoat on the screen makes it scratch- and abrasion-resistant, ensuring accurate and sensitive response to the users touch, even with heavy daily use.

Durability and reliability were two very important characteristics for the ovens control panel, says Diane Valachovic, chief operating officer, TMIO, Inc. One critical aspect was the durability of the gasket that lies between the touch screen and the LCD. We saw that the 3M touch screens, heavily used in other industries, demonstrate proven durability in this area.

Among its recent developments, 3M Touch Systems has demonstrated MicroTouch Interactive Surface Technology. This is said to allow the application of a touch interface to nearly any surface. It is constructed on a flexible, polyester layer that can be laminated to the front of a surface, to the back of a surface or applied to a contoured surface. The substrate for lamination can be plexiglass, polycarbonate, plastic, glass, laminated glass, or any other non-conductive surface. In addition, it can support on display use with LCD panels or off display use creating touch pad or button interface designs not using a display.

What makes this technology unusual is that it is flexible, and so can be placed in a variety of locations where touch controls havent been used before, says Moran. It gives designers the ability to use different size or form factors or aspect ratios. It allows a circular control surface, which some touch technologies cant do. As this is a new technology for us, we are engaging with designers about possible applications.

Pelikon (Cambridge, England) developed what it describes as the worlds first flexible printed segmented electroluminescent (pSEL) display. Less than a 1/2 mm thick, this is a light-emitting display. The company says the pSEL is available for sizes as small as a watch display or as wide as a dishwasher. To demonstrate how thin and flexible the display, driver and power source can be, the company has engineered a display for a credit card-sized chip card.

In a microwave oven, the company provided a control that combined the pSEL technology with an LED display. The pSEL display changes as buttons are pushed, and is only on during programming; the LED clock is always on.

Displays are printed on a flexible plastic film enabling touch screen functionality with the tactile feel of traditional buttons. The displays are self-colored with black and chrome versions that match the microwave ovens color, providing a sleek look. Icons are hidden until needed, considerably simplifying the look of the control panel with the user only being presented with the information he or she needs at any point. Touch the control panel lightly and the display lights up, showing only minimal high level functions like one-touch cook, time and start. From a simple menu, the user can reveal more of the interface enabling more specific and complex interaction when needed.

Big advantages of this technology are that it differentiates the appliance in function and appearance from others, and makes it easier to use, says Melvyn Collins, director of sales and marketing. This kind of technology can help make the kitchen a more attractive, interesting place. Further down the road, well see appliances that make use of the displays thinness and flexibility. We will likely see displays on curved surfaces, or perhaps on handles.

What is being billed as the worlds smallest television screen has been shown by MicroEmissive Displays Ltd. (Edinburgh, Scotland). The company uses licensed polymer light-emitting diode (P-OLED) technology from Cambridge Display Technology (Cambridge, England). MEDs approach allows for a much-reduced bill of materials-and reduced cost for display manufacturers-by integrating many of the functions of video displays into its CMOS chips. Drive electronics and frame store controller logic, for example, can be built in, eliminating the need for additional circuitry. This approach complements one of the advantages of P-OLEDs: they are emissive devices and do not need bulky and energy consuming backlights, as most LCD displays do.

Overcoming Programming

Electromechanical controls have one advantage over electronic controls-they do not require programming. Programming can be time-consuming, while the software can use up valuable microprocessor memory. Amulet Technologies (Santa Clara, California, U.S.) offers an alternative, with its graphical operating system in silicon. This chip is a combination LCD controller and microprocessor operating a graphic operating system. The dedicated microprocessor for the graphical user interface (GUI) frees the host microprocessor. This approach can be applied to new product design or to established products needing a midlife remodel. Customers can create a graphical GUI or skin without altering the applications microcontroller or code.

Since the host processor runs the application, not the GUI, it may be possible to use a smaller, less expensive processor. The code for the application and the GUI are partitioned; no debugging is needed and the application runs faster. The GUI is created with HTML tools including GIF and JPEG graphic formats, and uses any Windows-based fonts.

Home Comfort Zones (Beaverton, Oregon, U.S.) made use of the chip with its residential climate control system. The inventor, who has a degree in physics, first came up with this approach for his house in 2002, reveals John Ott, vice president sales and marketing of HCZ. He found that on some days, there would be a 20 degrees fahrenheit differential in parts of his 3,500 square foot house. Within several hours of installing his prototype, he had all rooms within plus or minus 2 degrees fahrenheit.

When we were looking into getting the system into production, we were using a personal digital assistant (PDA) as the controller, since it was easy to program and readily available. But we started having doubts, Ott explains. For one thing, what happens if some thrifty consumer started carrying the PDA around rather than keeping it in the house? We were also concerned that the screen was too small. Fortunately, we came across Amulet in 2003. It had a unique approach, and the chip was a powerful one with the least work for us. By adding the chip we were able to very quickly develop a sophisticated user interface without the heavy lifting. The Amulet solution allowed us to easily do things like show a 24-hour energy graph per room, have context sensitive help, and develop a simple interface that allows users to set a temperature for each room in the house. Our product is easier to use than a programmable thermostat, but far more sophisticated.

These controls are used on a panoramic x-ray machine for the human jaw from Sirona Dental Systems GmbH (Bensheim, Germany). The dual tip keypad from Schurter GmbH (Engingen, Germany) combines the advantages of a membrane keypad with those of the two-step switching technique. With one keypoint, two completely different switching operations can be achieved. The Dual Tip keypad is available in two versions. With the switch-snap version the first contact is made without any notice to the user. Only the second contact gives tactile feedback. The use of this dual contact function is primarily for applications requiring high-level security, where a second, separate switch is required for triggering an indirect control command. With the double click version, both contacts give tactile feedback and therefore allow for conscious controlling of two different operations. The operator can control two functions (such as slow/fast or request/confirmation) via one tip point, and can identify the two switching points.

Behind Displays

When designing electronic displays, serious forethought must be given to the application environment. According to the 3M Industrial Adhesives & Tapes Division, reliability and service life are the major considerations when an appliance producer designs or specifies an appliance control panel or display. The components need to be resistant to chemicals such as detergents and household cleaners, and have resistance to environmental factors like humidity, moisture, temperature, etc.

Display and control panel producers are also looking for ways to eliminate process steps to improve efficiencies, says Tanya Richert, marketing development administrator. 3Ms proprietary adhesives, long used in membrane switches, are said to offer this resistance to hostile environments and chemical exposure, as well as high cohesive strength. 3Ms Industrial Adhesives & Tapes Division introduced a White Opaque Spacer designed to eliminate the flood coat process step for display and control panel producers. 3M also says it has configured its business to be fast and flexible in meeting customer requirements, and developed a program designed to deliver custom needs in a quick timeframe.

Brian Williams, marketing manager of Minco (Minneapolis, Minnesota, U.S.) points out that as displays operate in lower temperatures, they start to respond sluggishly and characters dont show up as brightly. The characters need an added heater to bring them up to their proper operating temperature, says Williams. In the appliance industry, applications needing heat can include anything that operates outside. One example is ruggedized laptop computers used by utility companies.

Our Thermal-Clear transparent heaters can be sandwiched between a display and backlight. In this position they use very low watts per square inch. There have been times when companies had realized too late the need to include heaters. In such cases, they might retrofit the clear fine-wire heaters onto the tops of the display with double-sided pressure-sensitive tape. This approach can be hard to apply, and the heater needs to put out more wattage. It is better to plan ahead.

In displays, more applications are taking advantage of thin-film transistor (TFT) technology, which allows the use of full motion color video, says Jay Tan, applications engineer at AZ Displays (Aliso Viejo, California, U.S.). We are finding that companies now will often opt for TFT displays, even if it is not a full-motion application, simply because the appearance is a little better. Appearance is important, with companies looking for panels that are better looking as well as functional.

The proliferation of new products with LCDs and the trends toward larger size and greater thinness have created challenges for manufacturers in terms of higher temperature performance, optical quality and durability, says Todd Hoff, market directordisplays, GE Advanced Materials (Pittsfield, Massachusetts, U.S.). With this in mind, the company has expanded its Illuminex diffuser film family of optical films for LCD backlighting applications. The smallest applications are 5.8 inches and move up into larger sizes for products including televisions, notebook PCs and computer monitors. The company says its film offers advantages over traditional coated PET films by eliminating the coating. This coating can reportedly experience failures from flaking, voids and scratching of light guides, resulting in poor yields.

Man Yu, engineering manager at Kingbright Corporation (City of Industry, California, U.S.) notes a trend toward smaller controls and components in major appliances. Control size wasnt such a concern years ago, compared to consumer electronics. But increasing competition and more complex functions are having a lot of major appliance producers look at lean manufacturing. One way we can help is with our surface-mount LEDs, which can speed the manufacturing process and improve efficiency. We also offer more high-end colors, such as blue and white, and in fact have a full spectrum of colors.

One way to distinguish an appliance display is with increased panel brightness, says Brian Spahnie, research and development engineer at Lumitex, Inc. (Strongsville, Ohio, U.S.), Our fiber optic illumination technology is uniquely suited to take advantage of new high-bright, ultra-compact LEDs to offer a really bright user interface device for our customers. The companys LED Light Engines combine one or more of the high-power LEDs with a woven or fiber optic panel. A special collimating lens captures then focuses the light from the LEDs to the fiber optic panel. Encased in an aluminum housing that acts as a heat sink, the assembly provides as much as 20 to 50 times increased panel brightness by driving the high-power LEDs at a higher current through more efficient heat management.

High readability is an important consideration when a display is being viewed in bright sunlight or without a backlight. A solution proposed by Optrex America, Inc. (Plymouth, Michigan, U.S.) is a new series of highly reflective (HR) monochrome graphic and character LCDs. The HR transflective STN LCD modules provide high contrast black pixels on a silvery, winter white background. This background reflects back a high percentage of ambient light. The HR series LCDs are said to provide exceptional clarity, sharpness and readability in all types of ambient lighting conditions. At the same time, they give designers an attractive display in an industry standard configuration that enhances the functionality and appearance of an end product.

Enhancing functionality and appearance are, indeed, critical roles for controls and displays of all kinds. As appliance producers venture in new and imaginative directions, look for control panels to be at the heart of their vision.


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