Light Projection System Changes Objects’ Color and Patterns

Researchers at MIT have developed a method to rapidly change imagery on an object’s surface. The system, “ChromoUpdate,” pairs an ultraviolet light projector with items coated in light-activated dye. The projected light alters the reflective properties of the dye to create colorful new images in a matter of minutes. The technology may accelerate product development by allowing developers to showcase multiple color schemes and designs with a single prototype.

The new system builds on a previous programmable matter system developed by the researchers called “PhotoChromeleon.” That system was the first to show the researchers that it could have high-resolution, multicolor textures they could program over and over again, said lead author and postdoctoral researcher Michael Wessely.

A new system uses UV light projected onto objects coated with light-activated dye, such as this previously pink phone case, to alter the reflective properties of the dye, creating images in minutes. Courtesy of Michael Wessely, Stefanie Mueller, et al.

That system used a lacquer-like ink composed of cyan, magenta, and yellow dyes. An object coated with this ink could then be reprogrammed using light. First, UV light from an LED was shone on the ink to fully saturate the dyes. Next, the dyes were selectively desaturated with a visible-light projector to bring each pixel to its desired color and leave the final image behind.

Tests demonstrated that it took about 20 min for the system to update an image.

ChromoUpdate takes advantage of fast programming cycles — things that would not have been possible before, Wessely said. Rather than an LED, which uniformly blasts the entire surface, ChromoUpdate uses a UV projector that can vary light levels across the surface. This grants the operator pixel-level control over saturation levels.

“We can saturate the material locally in the exact pattern we want,” Wessely said.

The selective saturation procedure allowed designers to create a black-and-white preview of a design in seconds or a full-color prototype in minutes, which therefore enables multiple designs to be tested in a single work session.

“You can actually have a physical prototype to see if your design really works,” Wessely said. “You can see how it looks when sunlight shines on it or when shadows are cast. It’s not enough just to do this on a computer.”

The team hopes to improve the technology and broaden its potential. Currently, the ink is specialized for smooth rigid surfaces such as mugs, phone cases, and cars. The researchers aim to work with flexible, programmable textiles. The researchers have partnered with a group of textile makers in Paris to see how ChromoUpdate could be incorporated into the design process.

The research will be presented at the ACM Conference on Human Factors in Computing Systems.