Design and implementation of a digital LED desk lamp using the halftone method and a touch pad

In this paper we propose a design of a digital LED desk lamp (DLDL) which consists of two parts: an LED array and a control unit with a touch pad. The LED array includes both LEDs and a constant current source not only to ensure that every LED receives a fixed current and but also to provide a uniform brightness. We use the halftone method which provides an on/off control for each LED of the array, transforms different gray levels into LED array patterns and uses those patterns to maintain digital levels of brightness. Our halftone method is similar to the PWM method of adjusting the brightness; however, it provides a digital control for the brightness of the LED array. In the digital control panel we use the capacitive sensor to design the touch pad and to replace the traditional mechanical button to provide a user-friendly interface.