Press Release as Word Document

Intelligent sensors with EL light

New, innovative technologies such as electroluminescent lamps (EL) and printed sensors can complement currently used technologies for vehicle controls. So-called Intelligent Surfaces provide an elegant way to integrate controls in assembly components, making them visible only when they are actually needed. This can achieve a significant increase in vehicle operator and passenger comfort.

The consistent striving of automobile manufacturers to provide consumers with products that offer higher comfort, convenience and value is reflected in particular by the large number of instruments and controls found in vehicles. Especially the instrument panels of automobiles built in the 1990s, but also of many current vehicles, contain numerous manually operated controls for various functions, from fog lights to air conditioning. All of these buttons, knobs and switches require a certain depth in the installation cavity to activate the particular function. In addition, every single control or instrument has to be visible and identifiable as well as indicating its on-/off-state, not only in daylight but also during the hours of dusk, dawn or darkness. This requires appropriate illumination with a low intensity for position lighting and high intensity to indicate that the device is “on.“ In the past, conventional incandescent light bulbs were used for such applications, and more recently, LEDs (light-emitting diodes). The combination of the switching/control functions with respective lighting is a complex effort if a reasonable degree of luminous homogeneity is to be achieved. For all onboard LEDs to emit their light with equal intensity, the brightness of all the individual onboard LEDs must be coordinated. This is a very costly manufacturing process step, particularly if a large number of LEDs are installed in the car.

The fact that many consumers found cockpits featuring a large number of controls “cluttered“ called for simplification. The automotive industry responded to this demand by eliminating many of the controls and integrating them into the graphic interfaces of more recent onboard computers such as the BMW iDrive or Audi MMI. Via the graphic interface, equipment like radios, navigation or air conditioning systems can be operated. Theoretically, all manually operated controls could be replaced by this approach. But these newer systems have been criticized to some extent as well. The integration of too many functions may require users to navigate their way through extensive menus. In addition, the operation of such systems is complicated by the fact that it is not always obvious under which menu item the user will find the desired function.

The yellow brick road to a solution of this problem could be the combination of an intuitive-to-operate onboard computer system with easily accessible controls. This is possible through the integration of new types of sensors. Due to their extreme flatness these sensor systems can be installed in areas that are within easy reach of the operator but that do not provide sufficient space for the installation of conventional controls. They increase the level of user comfort by responding to the approach, touch or slight pressure exerted by a human finger. This mechanism to activate the function can be achieved capacitively, resistively, or via the piezoelectric effect. With the capacitive sensor the downstream electronic system evaluates the capacity change, with the resistive sensor the resistance change, and with the piezoelectric sensor the voltage change.

The major advantage of these sensors is that they can be printed on films or sheets. This means that they contain no more mechanical components that are subject to wear. The sensors are printed with pictograms symbolizing their respective functions. To ensure that their position is also visible in the dark they are combined with an EL lamp. This new type of switch can be configured such that merely those functions which are needed for a particular application at a specific point in time are illuminated or that “child“ switching functions are only visible if the respective “parent“ switch is active. This limits the number of permanently illuminated controls and facilitates the operator’s hand-eye coordination. As a result, complex applications can be operated easily, and operating errors reduced.

Another special advantage of this EL lamp/sensor combination is its moldability and suitability for in-mold decoration. This means that these types of controls can be installed in virtually any desired location of the vehicle interior (center consoles, door panels, instrument panels, etc.) without the need to insert respective fixtures, supports, etc. In addition, the fact that all components of the switch (sensor, EL light and pictogram) are printed on a film or sheet results in major cost savings.

At the moment, most drivers and passengers prefer controls like buttons protruding from the instrument panel that are activated by significantly depressing them. However, concerns about the elimination of "mechanical feedback" are completely unfounded: new design techniques enable the creation of molded surfaces, haptics can be adapted individually, and visual and/or acoustical feedback can be controlled as needed. In addition, surfaces can be realized that are easy to clean based on the material selected and due to the elimination of gaps that typically turn into dirt traps.

In view of the numerous obvious advantages of this new technology it is anticipated that this innovative generation of controls will make its way into future generations of automobiles.

Schreiner VarioLight’s core competency is the printing of delicate structures such as those used in sensors or EL lamps and the combination of both. These capabilities put Schreiner VarioLight in the position to provide competent and reliable support to OEMs and their suppliers in development and production.

For further information:
Schreiner VarioLight, a divison of
Schreiner Group GmbH & Co. KG
Bruckmannring 22
85764 Oberschleißheim
Phone: +49 89 31584-5494
Fax: +49 89 31584-5420
info@schreiner-variolight.de
www.schreiner-variolight.depresse@schreiner-group.de