Apparatus and method for driving LED display panel
The present disclosure provides devices, circuits, and methods for driving an LED display panel, so as to ensure the delivery of equal global charge at minimum gray scale. In one example, the circuit of the present disclosure includes a current source, a detection module, and a measurement module. The current source is configured to generate a current signal for the LEDs. The detection module is configured to detect a forward voltage of the LEDs in response to a low current applied to the LEDs. The detection module is further configured to hold the detected forward voltage. The measurement module is configured to measure a time period for an anode voltage of the LEDs to rise to the detected forward voltage in response to a display current applied to the LEDs.
1. A method for driving an LED display panel, comprising:
initializing a plurality of LEDs of the LED display panel; and
operating the LED display panel by supplying a driving signal to the LEDs so as to illuminate light with desired brightness,
wherein initializing the LEDs comprises determining a compensation parameter of the LEDs; and
wherein operating the LED display panel comprises:
generating a pre-determined driving signal;
modifying the pre-determined driving signal of the LEDs using the compensation parameter to obtain a modified driving signal; and
supplying the modified driving signal to the LEDs,
wherein determining the compensation parameter comprises determining a rise time of a forward voltage for an LED selected from the LEDs of the LED display panel,
wherein the rise time is the compensation parameter,
wherein modifying the pre-determined driving signal comprises delaying the pre-determined driving signal by the rise time of the forward voltage,
wherein the pre-determined driving signal is a pulse width modulation signal, and
wherein delaying the pre-determined driving signal by the rise time of the forward voltage is accomplished by adding the rise time of the forward voltage to a tail-end of a PWM driving signal as a delay.
2. The method of claim 1 , wherein determining the compensation parameter further comprises determining the forward voltage for the selected LED.
3. The method of claim 2 , wherein determining the forward voltage comprises supplying a low current to the selected LED and measuring a voltage across the selected LED until the voltage is stabilized, the stabilized voltage being the forward voltage.
4. The method of claim 1 , wherein determining the rise time comprises supplying a display current to the selected LED and measuring a time period for a voltage across the selected LED to rise to the forward voltage, the time period being the rise time.
5. The method of claim 1 , wherein the pre-determined driving signal is a pulse width modulation signal, and wherein delaying the pre-determined driving signal comprises extending a duty cycle of the pulse width modulation signal.