Device helps blind computer users '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 the blind and visually impaired 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 that is 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 is actually an array of movable metal pins used to recreate the shapes of objects. Push your thumb or your nose against one side of the bed of nails, and the pins bulge out on the other side, 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" that pushes the pins up as it passes underneath them, said John Roberts, who managed the graphic display development project. Once pushed up, the pins are locked in place until the display 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 the portrait of a person, pins would be raised to match the features of the face.

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

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

A crucial feature of the tactile graphic display is that it is expected to be relatively cheap and simple to manufacture. When produced in quantity, tactile graphic displays are expected to cost about $2,000, Roberts said.

NIST scientists plan to work with the National Federation of the Blind to field-test the display device and refine it, and then shop for a company to manufacture it.