Touch and see

Inspired by a child's toy and an old-style scientific graph printer, computer scientists and engineers from the National Institute of Standards and Technology have built a graphic display device that makes it possible for blind and visually impaired users to feel pictures and other graphics that are displayed on computer screens.

The "tactile graphic display" promises to be a breakthrough for blind and visually impaired computer users, said Marc Maurer, president of the National Federation of the Blind.

The device uses a bed of metal pins that can be individually raised to create a 3-D version of a picture, map, graph or other graphic displayed on a computer screen. The user can then feel the image.

Created at the request of visually impaired computer users, the display device uses the same concept found in a toy called a "bed of nails." The toy uses a set of movable metal pins to re-create the shapes of objects. Push your thumb or nose against one side of the bed of nails, and the pins on the other side bulge out, creating a 3-D image of your thumb or nose.

The tactile graphic display uses a bed of 3,600 pins arranged in a 5-by-7-inch rectangle. The pins are pushed up by a converted x-y plotter, a printer that uses software-driven pens to draw scientific graphs on paper.

"We took the pen out and replaced it with a solenoid," which pushes the pins up as it passes underneath them, said John Roberts, who managed the graphic display development project for NIST. Once pushed up, the pins are locked in place until the device is instructed to draw the next graphic.

To display a map of the United States, for example, pins would be raised to match the nation's borders and the outlines of the states. For a portrait of a person, pins would be raised to match the features of his or her face.

The device generally displays simple graphics better than complicated ones, Roberts said. Too many details in a graphic make the display harder for blind users to interpret, and many details take a long time to print, said Roberts, who unveiled the device at the National Federation of the Blind's headquarters in Baltimore Oct. 24.

A map that shows the outline of Texas takes about 10 seconds to draw, but a detailed picture takes much longer, he said.

Unlike similar devices, the tactile graphic display is expected to be relatively cheap and simple to manufacture. When produced in mass quantity, the displays are expected to cost about $2,000, Roberts said.

The few that are available today are much more expensive, said Curtis Chong, director of technology for the National Federation of the Blind. "We have one from Japan that costs 42,000 bucks."

Chong said the NIST device "has great potential" but will require more work to move from prototype to commercial product.