A display substrate includes a gate line, a gate insulating layer, a data line, a thin-film transistor, a storage line, a passivation layer, a color filter layer, a pixel electrode, a first light-blocking layer and a second light-blocking layer. The laser scanner also includes a control and evaluation unit which, for a multitude of measuring points, determines the distance to the object. Outer switch networks of switches Sa and Sb selectively switch the outer strings to reference voltage terminals Vref and Vref for selectively coupling selected portions of the outer strings to the respective voltage reference terminals for decrementing the inner string in steps corresponding to one MSB between the terminals. Each of the valves has a closed position for preventing a free flow of fluid between the central conduit and its associated main conduit and have an open position for enabling the free flow of fluid between the central conduit and its associated main conduit.