1-Hour Brainstorm Gave Birth to Digital Imaging

Even today, Willard S. Boyle can remember the noise the boss's phone made when it rang on his desk about 8:30 a.m. back in the late '60s. It was the legendary Jack Morton, vice president of electronic technology at Bell Laboratories, and he wasn't calling to say good morning.

"It was not a welcome sound," Boyle recalled. Bell was investigating new ways of storing data, and the hot technology at the time was something called "magnetic bubbles." Morton, who died in 1971, "was enthralled with magnetic bubbles," Boyle said.

Unfortunately for Boyle, he was a semiconductor guy. "So what are you working on?" Morton would ask. He called every two or three days, and Boyle and collaborator George E. Smith soon got the idea that their funding might disappear unless they invented something in a hurry. So they did.

In a one-hour brainstorming session in late 1969, Boyle and Smith drew up the basic design for a memory chip they called a "charge-coupled device," more familiarly known as a "CCD." It worked fine for data storage -- but anybody could see that its future lay in its breathtaking potential for capturing and storing images.

CCDs are what made digital still and video cameras possible. CCDs can X-ray a child's teeth, see a person's insides during laparoscopy, and produce stunning images of the Martian desert from the "eyes" of NASA's traveling rovers.

Although less familiar to the public, Boyle and Smith's device has become as ubiquitous as the laptop computer or the laser. These integrated circuits capture and store light in devices as mundane as supermarket bar-code readers and as spectacular as the Hubble Space Telescope.

Tomorrow, the National Academy of Engineering will recognize their breakthrough, awarding them the $500,000 Charles Stark Draper Prize, one of engineering's most prestigious honors.

"It is a great innovation," said Ruzena Bajcsy, the University of California at Berkeley computer scientist and robotics specialist who nominated the two researchers for the prize. "It enables you to have miniaturized cameras, to look inside the human body, to do all kinds of surveillance. There's nothing like it."

Boyle, now 82 and living in Halifax, Nova Scotia, was executive director of Bell Labs' semiconductor division in 1969. Smith, 75, and now living in Barnegat, N.J., worked for him. And both worked for Morton, a legendary figure in the development of transistors in the late 1940s at Bell Labs in Murray Hill, N.J.

Impelled by the need to invent a data storage device and protect their budget from being swallowed by the department of magnetic bubbles, Boyle summoned Smith one afternoon, and together, on a blackboard, they sketched out a new device.

A CCD consists of a silicon chip sensitive to light and able to store packets of charges in tiny wells, or capacitors, inside it. When photons hit the silicon in the CCD, they dislodge electrons, creating a charge proportional to the light's intensity. The capacitors collect and store the charge. Each CCD is an array of these capacitors, forming pixels.

Once the charges are stored, voltage is cycled through the device, deforming the wells and causing the charges to travel from pixel to pixel in an orderly fashion until the entire "charge packet" is dumped into a signal processor that digitizes the collected charge to reproduce the original image.