2008

Tactile Feedback for Touch-input Devices

Flexible and Efficient Integration

In theory, the technology could be applied to any size touch-input device, but the company’s current solutions work for screens and panels with diagonal measurements of around 2.5 to 36.0 inches.

System architecture includes (1) control software, installed on a dedicated or already-existing microprocessor or on an Immersion-supplied control board, (2) actuator(s), either an off-the-shelf eccentric rotating mass (ERM) or an Immersion-designed device(s), (3) a tactile effects library, and (4) an API for calling tactile effects from the host application.

Immersion offers a selection of three TouchSense integration kits designed to allow rapid prototyping across a range of touch-input device sizes. The kits include actuator samples; control boards with software installed; reference schematics; mechanical and electrical integration guidelines; and an SDK.

Control Software

If a circuit board is preferred, two types are available, for either RS-232 or USB communication. If the embedded approach works best, the TouchSense runtime executable would be provided.

Actuation

Correlating actuator size and type to touch-input device size is based on mass, mounting methods, cost, space, power, and type of tactile effects. However, as a very rough rule of thumb, touch-input devices over 9 or 10 inches will probably need an Immersion lateral actuator. Touch-input devices less than 6 inches will probably use an ERM inertial actuator. In the 7-9-inch range, the choice might go either way.

Tactile Effects Library

The tactile effects library includes a variety of effects so controls can be clearly distinguished and products differentiated. The haptics system gives designers a convenient method for experiencing effects, then selecting the ones that would be the most appropriate for the application and including them in the user interface design. The library was developed through consideration of human touch physiology and waveform design and is optimized for common usage scenarios.

API

The TouchSense API is used to call the tactile effects from the host application. The TouchSense software development kit includes 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 is also included.

Time and Cost of Design

All TouchSense kits include clear guidelines for the full integration process. In addition, Immersion often works with integrators to support faster prototyping and a high-quality design. The company has been developing and implementing its tactile feedback technology for over 15 years and has developed significant expertise in understanding the hardware requirements and how to adjust the elements to achieve the best possible results. Integrators usually complete hardware and software prototyping in a week or less.

The system has been successfully integrated into many product designs, and millions of devices incorporating the technology have been shipped throughout Asia, Europe, and the U.S. Cost-effective implementations are possible for products ranging from small, high-volume personal navigation devices to larger, low-volume kiosks.

This article was written by Steve Kingsley-Jones, Director of Product Management for Immersions’s Touch Interface Products Group (San Jose, CA). For more information, contact Mr. Kingsley-Jones at This email address is being protected from spambots. You need JavaScript enabled to view it., or visit http://info.hotims.com/15142-201.

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