Industry Patents

A white-light emitter is disclosed, in which light from blue light-emitting diodes strikes an active area of a phosphor sheet. The active area absorbs a portion of the blue light and emits phosphor light in response to the absorbed blue light. The emitter includes a stretcher that controllably stretches the active area of the phosphor sheet. The white light output spectrum of the active area has a characteristic color temperature that increases as the phosphor sheet is stretched, and decreases as the phosphor sheet contracts. As the phosphor sheet is stretched, the thickness of the active area decreases, the received blue light encounters fewer phosphor particles within the active area, the absorbed portion of the blue light decreases, the emitted phosphor light decreases, and the active area has a white light output spectrum that becomes weighted more heavily toward the blue light and less heavily toward the phosphor light.