Touchscreens That Touch Back

June 23, 2007
Immersion Corporation’s tactile feedback technology for fixed or portable device touchscreens provides confirming tactile response to user interactions. Unmistakable tactile cues can solve usability problems and enhance the user experience. Depending on the OEM product design, the technology’s components can vary in form, but the basic architecture is the same, allowing the system to exert high-speed control over one or more actuator(s) (motors). In small devices, the actuator may be similar to a small pager motor used in a mobile phone. For larger devices, actuators optimized for a range of touchscreen sizes and weights are available. When the user presses a graphical button, the tactile feedback system drives the actuator according to a preprogrammed tactile “effect” (vibration). The actuator movement supplies the perception that the graphical button moves, seeming to press and release as if it were mechanical. The system can synchronize tactile effects with sound and display changes, creating a more engaging, multisensory experience. By varying the frequency, waveform, amplitude, and duration of the vibration, a wide range of response is possible, supporting various HMI features: Graphical buttons can simulate the familiar up and down clicks of physical buttons. Menu items can be programmed to supply a light pulse sensation or a confirming push-back response. Controls can exhibit increasing or decreasing vibrations corresponding to motor or fan speed, radio volume level, lighting levels, or other parameters. Scrolling displays can provide a pulse as each item displays and a special vibration to signal when the first or last items have been reached. The technology can work with touchscreens and digital-switch control panels of a wide range of sizes. Integration has been successfully achieved for many product designs, and millions of devices with the technology have been shipped throughout Asia, Europe, and the U.S. The tactile feedback system architecture includes (1) actuator(s), either a pager motor or larger custom-designed devices, (2) control software, either installed on a control board or embedded in the product’s main microprocessor, (3) a tactile effects library, and (4) a programming interface for calling tactile effects from the host application. Control Software: For medium and large screen systems, application-specific circuit boards have been developed for either RS-232 or USB communication. For the latter, an optional USB hub provides convenient connections to subsystems. If the embedded approach is used, a runtime executable is provided. Actuation: As for the choice of actuation, it should be thoughtfully selected to meet performance and life requirements. Design guidelines for actuator mounting and control circuitry are also part of the tactile feedback system. To actuate larger touchscreens, two sizes of actuators are available, both optimized for generating high forces with small displacements. The type and number of actuators depends on the size, weight, and implementation of the touchscreen or panel. Guidelines for positioning and mounting the actuators are flexible and allow the tactile feedback technology to be integrated into a wide range of product designs. In addition, some touchscreen implementations may require a carrier (frame) for mechanical integration. Tactile Effects Library: The tactile effects library includes a wide variety of effects so that the feel of various touchscreen controls can be clearly distinguished and functions differentiated. The tactile feedback system gives designers a convenient method for choosing appropriate effects and including them within the HMI. Programming Interface: Software-integration guidelines explain the use of a streamlined API to call the tactile effects from the host application. For some implementations, a software development kit can be used, which gives designers several programming options including a Windows ActiveX control, a cross-platform API in source code form, and communications support for custom interfaces. Sample code and a full description of the process of adding tactile feedback to the host application are also included in the system. To evaluate the technology, integration kits and touchscreen demonstration units with example applications are available. Touchscreens with tactile feedback are just beginning to come to market, but already they show much promise for improving the HMI and promoting a more intuitive, engaging, and satisfying experience for the user.