Electroluminescent display device
An electroluminescent display device includes a pixel configured to display an image based on a difference between a display data voltage and a first reference voltage, a driving voltage generation circuit configured to supply the display data voltage to the pixel through a data line, and a sensing circuit configured to supply the first reference voltage to the pixel through a sensing line. The sensing circuit includes a sensing channel terminal coupled to the sensing line, a switch coupled between the sensing channel terminal and an input terminal for the first reference voltage, and a sampling circuit configured to sense a voltage of the sensing line which has changed from the first reference voltage independent of driving characteristics of the pixel in a vertical blank period in which the switch is turned off.
1. An electroluminescent display device, comprising:
a pixel configured to display an image based on a difference between a display data voltage and a first reference voltage;
a driving voltage generation circuit configured to supply the display data voltage to the pixel through a data line; and
a sensing circuit configured to supply the first reference voltage to the pixel through a sensing line, the sensing circuit including:
a sensing channel terminal coupled to the sensing line;
a switch coupled between the sensing channel terminal and an input terminal for the first reference voltage; and
a sampling circuit configured to sense a voltage of the sensing line which has changed from the first reference voltage independent of driving characteristics of the pixel in a vertical blank period in which the switch is turned off.
2. The electroluminescent display device of claim 1 , wherein the vertical blank period includes a first sensing period and a pixel sensing period in sequence, and
wherein the sampling circuit senses the voltage of the sensing line independent of the driving characteristics of the pixel in the first sensing period and subsequently senses a node voltage of the pixel in the pixel sensing period, the node voltage representing the driving characteristics of the pixel.
3. The electroluminescent display device of claim 2 , further comprising a non-inverting amplification circuit coupled to the sensing channel terminal, the input terminal for the first reference voltage and the sampling circuit, and enabled in the first sensing period.
4. The electroluminescent display device of claim 3 , wherein the non-inverting amplification circuit includes:
an operational amplifier having an inverting input terminal, a non-inverting input terminal coupled to the input terminal for the first reference voltage, and an output terminal;
a first resistor coupled to the inverting input terminal of the operational amplifier;
a second resistor coupled between the inverting input terminal and the output terminal of the operational amplifier;
a second switch coupled between the sensing channel terminal and the first resistor; and
a third switch coupled between the output terminal of the operational amplifier and the sampling circuit.
5. The electroluminescent display device of claim 4 , wherein the non-inverting amplification circuit amplifies a difference between the voltage of the sensing line and the first reference voltage while the second switch and the third switch are in an on state in the first sensing period.
6. The electroluminescent display device of claim 3 , further comprising a second switch connected between the sensing channel terminal and the sampling circuit,
wherein the second switch maintains an off state in the first sensing period and maintains an on state in the pixel sensing period.
7. The electroluminescent display device of claim 2 , further comprising a non-inverting amplification circuit coupled to an input terminal for a second reference voltage higher than the first reference voltage, the sensing channel terminal, and the sampling circuit and enabled in the first sensing period.
8. The electroluminescent display device of claim 7 , wherein the non-inverting amplification circuit includes:
an operational amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal;
a first resistor coupled to the inverting input terminal of the operational amplifier;
a second resistor coupled between the inverting input terminal and the output terminal of the operational amplifier;
a second switch coupled between the sensing channel terminal and the first resistor;
a third switch coupled between the output terminal of the operational amplifier and the sampling circuit;
a capacitor having one electrode coupled to the non-inverting input terminal of the operational amplifier;
a fourth switch coupled between the sensing channel terminal and the other electrode of the capacitor; and
a fifth switch coupled between the non-inverting input terminal of the operational amplifier and the input terminal for the second reference voltage.
9. The electroluminescent display device of claim 8 , wherein the non-inverting amplification circuit amplifies a difference between the voltage of the sensing line and the second reference voltage while the second switch, the third switch, and the fourth switch maintain an on state in the first sensing period.
10. The electroluminescent display device of claim 7 , further comprising a second switch connected between the sensing channel terminal and the sampling circuit,
wherein the second switch maintains an off state in the first sensing period and maintains an on state in the pixel sensing period.
11. The electroluminescent display device of claim 2 , further comprising a non-inverting amplification circuit coupled to the input terminal for the first reference voltage, the sensing channel terminal, and the sampling circuit and enabled in the first sensing period.
12. The electroluminescent display device of claim 11 , wherein the non-inverting amplification circuit includes:
an operational amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal;
a first resistor coupled to the inverting input terminal of the operational amplifier;
a second resistor coupled between the inverting input terminal and the output terminal of the operational amplifier;
a second switch coupled between the sensing channel terminal and the first resistor;
a third switch coupled between the output terminal of the operational amplifier and the sampling circuit;
a capacitor having one electrode coupled to the non-inverting input terminal of the operational amplifier;
a fourth switch coupled between the sensing channel terminal and the other electrode of the capacitor; and
a fifth switch coupled between the non-inverting input terminal of the operational amplifier and the input terminal for the first reference voltage.
13. The electroluminescent display device of claim 12 , wherein the non-inverting amplification circuit amplifies a difference between the voltage of the sensing line and the first reference voltage while the second switch, the third switch, the fourth switch, and the fifth switch are in an on state in the first sensing period.
14. The electroluminescent display device of claim 11 , further comprising a second switch connected between the sensing channel terminal and the sampling circuit,
wherein the second switch maintains an off state in the first sensing period and maintains an on state in the pixel sensing period.
15. The electroluminescent display device of claim 2 , wherein a duration of a vertical active period preceding the vertical blank period is fixed independent of a frame frequency, and a duration of the vertical blank period changes according to the frame frequency.
16. The electroluminescent display device of claim 15 , wherein a first vertical blank period of a first frame frequency includes the first sensing period and the pixel sensing period, and a second vertical blank period of a second frame frequency includes the pixel sensing period and is free of the first sensing period, and wherein the second frame frequency is higher than the first frame frequency.
17. The electroluminescent display device of claim 2 , wherein electrical connection between the sensing line and the pixel is blocked in the first sensing period, and the sensing line is electrically coupled to the pixel in the pixel sensing period.
18. The electroluminescent display device of claim 1 , wherein the sensing line is charged with the first reference voltage in a vertical active period preceding the vertical blank period.
19. A system comprising:
a display panel;
a driver integrated circuit including:
a driving voltage generation circuit configured to supply display data voltage to the display panel through a plurality of data lines; and
a sensing circuit coupled to the display panel, the sensing circuit configured to generate digital sensing result data, the sensing circuit including:
a sensing channel terminal coupled to a sensing line of the display panel;
a switch configured to selectively couple/decouple a reference voltage used in a display operation to/from the sensing channel terminal; and
a sampling circuit configured to sense discharge characteristics of the sensing lines in which voltages decrease from the reference voltage during a sensing operation; and
a compensation integrated circuit configured to generate corrected video data based on the digital sensing result data.
20. The system of claim 19 , wherein the sensing line and a pixel of the display panel are continuously disconnected from each other during the sensing operation.