Pixel circuit using direct charging and that performs light-emitting device compensation

A display system comprising:

• a display panel comprising a plurality of pixel circuits, and a measurement and data processing unit that is external to the display panel;
• wherein each pixel circuit comprises:
• a light-emitting device having a first terminal connected to a first voltage supply and a second terminal opposite from the first terminal;
• a first transistor directly connected at a first terminal to a data voltage supply line from the measurement and data processing unit and directly connected at a second terminal to the second terminal of the light-emitting device, wherein the data voltage supply line is electrically connected to the second terminal of the light-emitting device when the first transistor is in an on state;
• a second transistor connected between the second terminal of the light-emitting device and a sample line to the measurement and data processing unit;
• a storage capacitor directly connected at a first plate to the second terminal of the light-emitting device and the second terminal of the first transistor, and directly connected at a second plate to a second voltage supply, wherein the data voltage supply line is electrically connected to the storage capacitor when the first transistor is in an on state and the storage capacitor discharges through the light-emitting device when the first transistor is in an off state;
• and
• the second voltage supply comprises a multi-level reference voltage supply, and the reference voltage supply boosts the discharge from the storage capacitor;
• wherein the measurement and data processing unit is configured to sample a measured voltage at the second terminal of the light-emitting device through the sample line, and to output a data voltage to the light-emitting device based on the measured voltage to compensate variations in properties of the light-emitting device.