Electroluminescent display apparatus

1. An electroluminescent display apparatus comprising:

a pixel including a driving element having a gate electrode connected to a data line and a source electrode connected to a reference voltage line; and

a pixel driving circuit for applying a sensing data voltage to the gate electrode of the driving element through the data line, detecting a source electrode voltage of the driving element, shifted from a sensing reference voltage based on the sensing data voltage, through the reference voltage line to obtain a detection voltage, calculating an offset voltage based on the detection voltage, and lowering a level of the sensing data voltage based on the offset voltage, in a plurality of vertical blank periods,

wherein:

the pixel driving circuit is configured to apply an n th (where n is a natural number of 2 or more) sensing data voltage to the gate electrode of the driving element in a vertical blank period of an n th frame;

the pixel driving circuit is configured to apply an n−1 th sensing data voltage to the gate electrode of the driving element in a vertical blank period of an n−1 th frame preceding the n th frame; and

the n th sensing data voltage is lower than the n−1 th sensing data voltage.

2. The electroluminescent display apparatus of claim 1 , wherein:

the pixel driving circuit is configured to detect an n−1 th detection voltage through the reference voltage line in the vertical blank period of the n−1 th frame and to increase the n−1 th detection voltage by an n−1 th offset voltage from the sensing reference voltage;

the pixel driving circuit is configured to detect an n th detection voltage through the reference voltage line in the vertical blank period of the n th frame and to increase the n th detection voltage by an n th offset voltage from the sensing reference voltage;

the n th offset voltage is lower than the n−1 th offset voltage; and

the n th sensing data voltage is lower than the n−1 th sensing data voltage by the n−1 th offset voltage.

3. The electroluminescent display apparatus of claim 2 , wherein, when the n th offset voltage is 0 V, the pixel driving circuit detects the n th sensing data voltage as a threshold voltage of the driving element.

4. The electroluminescent display apparatus of claim 2 , wherein the n th sensing data voltage has a voltage level of “VF 1 −Σ n n-1 (offsetvoltage)”, and

the “VF 1 ” is a first sensing data voltage applied to the gate electrode of the driving element in a vertical blank period of a first frame, and the “Σ n n-1 (offsetvoltage)” is an accumulated offset voltage obtained by summating offset voltages up to the vertical blank period of the n−1 th frame from the vertical blank period of the first frame.

5. The electroluminescent display apparatus of claim 4 , wherein the pixel driving circuit comprises:

a reference voltage circuit for outputting the sensing reference voltage to the reference voltage line in the vertical blank period of the n−1 th frame;

a sampling circuit for sampling the n−1 th detection voltage through the reference voltage line in the vertical blank period of the n−1 th frame;

a timing controller for subtracting the sensing reference voltage from the n−1 th detection voltage to calculate the n−1 th offset voltage and calculating the n th sensing data voltage which is lower by the n−1 th offset voltage than the n−1 th sensing data voltage; and

a digital-to-analog converter for outputting the n−1 th sensing data voltage to the data line in the vertical blank period of the n−1 th frame and outputting the n th sensing data voltage to the data line in the vertical blank period of the n th frame.

6. The electroluminescent display apparatus of claim 5 , wherein, in the vertical blank period of the n th frame,

the reference voltage circuit is configured to output the sensing reference voltage to the reference voltage line,

the sampling circuit is configured to sample the n th detection voltage input through the reference voltage line, and

the timing controller is configured to subtract the sensing reference voltage from the n th detection voltage to calculate the n th offset voltage, and when the n th offset voltage is 0 V, the timing controller detects the n th sensing data voltage as a threshold voltage of the driving element.

7. The electroluminescent display apparatus of claim 1 , wherein, when a threshold voltage of the driving element is higher than 0 V, the pixel driving circuit detects the n th sensing data voltage as the threshold voltage of the driving element.

8. The electroluminescent display apparatus of claim 1 , wherein, when a threshold voltage of the driving element is lower than or equal to 0 V,

the pixel driving circuit detects an estimation sensing data voltage, different from the n th sensing data voltage, as the threshold voltage of the driving element, and

the estimation sensing data voltage is differently set based on a time at which the n th sensing data voltage is 0 V.

9. The electroluminescent display apparatus of claim 8 , wherein:

when n is a first value, the estimation sensing data voltage is set to a first voltage value;

when n is a second value, the estimation sensing data voltage is set to a second voltage value; and

when the first value is lower than the second value, the first voltage value is lower than the second voltage value.