CROSS-REFERENCE TO RELATED APPLICATION

The application claims priority from and the benefit of Korean Patent Application No. 10-2019-0053274, filed on May 7, 2019, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Field

Exemplary implementations of the invention relate to a display device and, more specifically, to a display device having at least one sensing target pixel and a driving method thereof.

Discussion of the Background

With the development of information technology, the importance of display devices, which are a connection medium between users and information, has been emphasized. In response to this, the use of display devices such as a liquid crystal display device, an organic light emitting display device, and a plasma display device has been increasing.

A display device may include pixels and display an image using a combination of light emitted from the pixels. Driving transistors included in each of the pixels may have different voltage-current characteristics due to process variations. For example, the driving transistors may have different threshold voltage values. Therefore, it is required to sense the threshold voltage values and in order to sense the threshold voltage values, sensing data voltage should apply to a sensing target pixel.

The above information disclosed in this Background section is only for understanding of the background of the inventive concepts, and, therefore, it may contain information that does not constitute prior art.

SUMMARY

Applicant realized that the sensing data voltage for sensing the threshold voltage value may not be supplied to the sensing target pixel when a supply time point of the sensing data voltage and a supply time point of a display data voltage overlap each other.

Display devices constructed according to the principles and exemplary implementations of the invention and driving methods thereof are capable of separating a supply time point of a sensing data voltage from that of a display data voltage.

Additional features of the inventive concepts will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concepts.

According to one aspect of the invention, a display device includes: a scan driver to receive a scan start signal and to supply scan signals of a turn-on level to scan lines in response to the scan start signal; a data driver to receive grayscale values and to supply data voltages corresponding to the grayscale values and a reference data voltage to data lines; pixels connected to the scan lines and the data lines, the pixels including display target pixels configured to receive the data voltages and at least one sensing target pixel configured to receive the reference data voltage; and a scan start signal adjusting unit to detect display target pixels among the pixels using the grayscale values and to adjust a phase of the scan start signal when at least one of the display target pixels comprises a sensing target pixel.

The data driver may be configured to sequentially receive the grayscale values, and the scan start signal adjusting unit may include a counter, the counter may be configured to: count a scan line number every time the data driver receives the grayscale values in units of scan lines and provide a first scan line number corresponding to an initial display grayscale value exceeding a reference value among the grayscale values and a second scan line number corresponding to a last display grayscale value exceeding the reference value among the grayscale values.

The scan start signal adjusting unit may further include a comparator, the comparator may be configured to generate a phase adjustment signal when a sensing target scan line number corresponding to the sensing target pixel is greater than or equal to the first scan line number and less than or equal to the second scan line number.

The scan start signal adjusting unit may further include a phase adjuster, the phase adjuster may be configured to adjust a phase of the scan start signal when the phase adjuster receives the phase adjustment signal and maintaining the phase of the scan start signal when the phase adjuster does not receive the phase adjustment signal.

The data driver may be further configured to receive a sensing grayscale value of the sensing target pixel and the reference data voltage may correspond to the sensing grayscale value.

The data driver may be configured to receive the sensing grayscale value and display grayscale values at different time points within one image frame period.

The phase adjuster may be configured to adjust the phase of the scan start signal to a time point earlier than a previous phase when the phase adjuster receives the phase adjustment signal.

The data driver may be configured to receive the display grayscale values after receiving the sensing grayscale value.

The phase adjuster may be configured to adjust the phase of the scan start signal to a time point later than a previous phase when the phase adjuster receives the phase adjustment signal.

The data driver may be configured to receive the sensing grayscale value after receiving the display grayscale values.

Each of the pixels may include: a first transistor having a gate electrode connected to a first node, a first electrode connected to a first power supply line, and a second electrode connected to a second node; a second transistor having a gate electrode connected to a data scan line, a first electrode connected to the data line, and a second electrode connected to the first node; a third transistor having a gate electrode connected to an initialization scan line, a first electrode connected to the second node, and a second electrode connected to an initialization line; a storage capacitor having a first electrode connected to the first node and a second electrode connected to the second node; and a light emitting diode having an anode connected to the second node and a cathode connected to a second power supply line.

The initialization line may be connected to a sensing unit. The sensing unit may include: a reference voltage terminal; a capacitor; and an analog-to-digital converter connected to a first electrode of the capacitor. In a sensing period, the initialization line may be connected to the reference voltage terminal, and then to the first electrode of the capacitor.

The data driver may be configured to supply the reference data voltage within the sensing period.

According to another aspect of the invention, a driving method of a display device including a scan driver to receive a scan start signal and to supply scan signals of a turn-on level to scan lines in response to the scan start signal; a data driver to receive grayscale values and to supply data voltages corresponding to the grayscale values and a reference data voltage to data lines; and pixels connected to the scan lines and the data lines, the pixels including display target pixels configured to receive the data voltages and at least one sensing target pixel configured to receive the reference data voltage, the driving method comprising the steps of: detecting the display target pixels among the pixels using the grayscale values; confirming whether or not at least one of the display target pixels comprises the sensing target pixel; and adjusting a phase of the scan start signal when at least one of the display target pixels comprises the sensing target pixel.

The data driver may be configured to sequentially receive the grayscale values. The step of detecting the display target pixels may further include the steps of: counting a scan line number every time the data driver receives the grayscale values in units of scan lines; and providing a first scan line number corresponding to an initial display grayscale value exceeding a reference value among the grayscale values and a second scan line number corresponding to a last display grayscale value exceeding the reference value among the grayscale values.

The step of confirming may further include the step of generating a phase adjustment signal when a sensing target scan line number corresponding to the sensing target pixel is greater than or equal to the first scan line number and less than or equal to the second scan line number.

The step of adjusting the phase of the scan start signal may further include the steps of: adjusting a phase of the scan start signal when the phase adjustment signal is received; and maintaining the phase of the scan start signal when the phase adjustment signal is not received.

The data driver may be further configured to receive a sensing grayscale value of the sensing target pixel and supply a reference data voltage corresponding to the sensing grayscale value, and the data driver may be configured to receive the sensing grayscale value and display grayscale values at different time points within one image frame period.

The step of adjusting the phase of the scan start signal may further include the step of adjusting the phase of the scan start signal to a time point earlier than a previous phase when the phase adjustment signal is received, and the data driver may be configured to receive the display grayscale values after receiving the sensing grayscale value.

In the step of adjusting the phase of the scan start signal may further include the step of: adjusting the phase of the scan start signal to a time point later than a previous phase when the phase adjustment signal is received, and the data driver may be configured to receive the sensing grayscale value after receiving the display grayscale values.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

