Display panel, driving method, and display device

A display panel, comprising:

• a plurality of data signal lines;
• a plurality of scan signal lines disposed to intersect the plurality of data signal lines to define a plurality of sub-pixels in an array;
• wherein the plurality of sub-pixels each comprises a pixel driving circuit, wherein the pixel driving circuit includes a driving transistor and an organic light emitting diode, wherein the organic light emitting diode has a threshold voltage for turning on;
• and
• an external compensation circuit comprising a power supply unit, a sampling unit and a data signal generation unit, wherein the external compensation circuit connects to the plurality of data signal lines, and transmits a compensated data signal via the plurality of data signal lines to the pixel driving circuit of each of the plurality of sub-pixels in a number of periods to compensate for the threshold voltage in a threshold compensation phase;
• wherein the power supply unit provides a current signal to the driving transistor and/or the organic light emitting diode of each of the plurality of sub-pixels;
• wherein the sampling unit samples a voltage signal of the driving transistor and/or the organic light emitting diode of each of the plurality of sub-pixels based on a current signal provided by the power supply unit, and compares the voltage signal with a pre-stored characteristic curve of the driving transistor and/or a characteristic curve of the organic light emitting diode of each of the plurality of sub-pixels to determine a degraded voltage of the driving transistor and/or the organic light emitting diode;
• and
• wherein the data signal generation unit generates the compensated data signal based on the degraded voltage of the driving transistor and/or the organic light emitting diode of each of the plurality of sub-pixels determined by the sampling unit, and provides the compensated data signal to the pixel driving circuits of each of the plurality of sub-pixels;
• wherein the display panel further comprising a first switch unit, a second switch unit, and a third switch unit;
• wherein the first switch unit comprises a plurality of first switches, each first switch-is turned on or turned off between the power supply unit and an associated data signal line of the plurality of data signal lines;
• wherein the second switch unit comprises a plurality of second switches, each second switch is turned on or turned off between the sampling unit and an associated data signal line of the plurality of data signal lines;
• and
• wherein the third switch unit comprises a plurality of third switches, each third switch is turned on or turned off between the data signal generation unit and an associated data signal line of the plurality of data signal lines;
• wherein in a first period of the threshold compensation phase, the first switch unit is turned on and sends out a first signal under control of a control terminal of the first switch unit, the second switch unit and the third switch unit are turned off, the power supply unit of the external compensation circuit transmits a fixed current signal to the associated data signal line connected thereto in response to the first signal from the control terminal of the first switch unit, and the associated data signal line transmits the current signal to a first node and a second node of the pixel driving circuit, terminal voltages at the first node and the second node change accordingly, after the power supply unit detects that a voltage of the first node is unchanged relative to a reference potential, the first switch unit is turned off;
• wherein in a second period of the threshold compensation phase, the second switch unit is turned on and sends out a second signal under control of a control terminal of the second switch unit, the first switch unit and the third switch unit are turned off, sampling unit of the external compensation circuit connected to the data signal line samples a voltage signal from the data signal line, and the voltage signal is a saturated voltage of the first node relative to the reference potential in the previous period;
• and
• wherein a timing in a third period of the threshold compensation phase is the same as the first period of the threshold compensation phase, and a timing in a fourth period of the threshold compensation phase is the same as the second period of the threshold compensation phase,
• wherein the third switch unit is turned on and sends out a third signal under control of a control terminal of the third switch unit, the first switch unit and the second switch unit are turned off, wherein a date signal generated by the data signal generation unit is transmitted to the associated data signal line, in response to the third signal from the control terminal of the third switch unit.