US Patent 7716990 Portable electroluminescent diagnostic gauge

A self contained internally illuminated diagnostic gauge used to display the magnitude of physically measured quantities in low or no light areas. The diagnostic gauge uses mechanical gauge needles to indicate the magnitude of the measurements on a dial. The dial is illuminated internally with a thin and flexible electroluminescent panel layer. This electroluminescent layer emits photons of light in response to a applied electrical energy. The electrical energy is supplied from a small battery system and driven through electronic circuitry both of which are contained inside of the gauge shell housing unit. The gauge shell has a removable battery cover that enables access to the power supply and the electronic drive circuitry of the device.