Design News for Mechanical and Design Engineers

Camarillo, CA--For the moment anyway, Sony may have the edge in the battle for the "lite laptop." Last November, the company introduced the Sony 505 to Japan--a PC notebook less than an inch thick and weighing under four lbs. The key to this little computer is the VersaPad Touchpad Sensor developed by Interlink Electronics. The 0.7-mm (0.028-inch) thick pad supports both mouse functionality and pen input for handwriting recognition and signature verification. Actually, one doesn't even need a pen. The pressure sensor translates finger-drawn characters into letters and numbers as well.

Traditional notebook touchpads are based on capacitive technology. A capacitive field remains awake, awaiting interruption by a conductive material, such as a finger. An ordinary plastic stylus won't work. The electronics in a capacitive pad must be kept close to the sensor or else environmental problems such as noise will disrupt the circuitry. Because the VersaPad sensor is activated by pressure, it can transmit the signal to electronics mounted remotely, typically on the computer motherboard.

The touchpad requires 2 to 4 mA of energy when in use. When idle, it goes to sleep, requiring a 0.01 (mu)A. More traditional touchpads use a constant 4 to 10 mA.

"Our semiconductor touchpad sensor with combined mount depth, energy savings, and pen input will help revolutionize the human interface of notebook computers, wireless devices, and downsized electronics of all types," says Keith Roberts, director of corporate communications at Interlink.

Interlink also expects to use the thin sensor for cell phones, two-way pagers, handheld data collection devices such as bar code scanners, even security systems. The touchpad supports CyberSIGN signature capture software. By matching the signature, pen pressure, and the time it takes a person to sign his or her name, the authenticity of the signer can be biometrically verified. Instead of spending thousands on a retina scan system, for example, this could provide a $30 key solution, says Roberts.

Interlink's VersaPad sensor is now available in the U.. Sony, however, has not yet announced when the English version of its newest laptop will be released.