CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean patent application number 10-2020-0078690 filed on Jun. 26, 2020, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

Field of Invention

Various embodiments of the present disclosure relate to a display device, and more particularly, to a display device capable of varying a driving frequency and a method of driving the display device.

Description of Related Art

A display device displays an image using control signals applied from an external device.

The display device may include a plurality of pixels. Each of the pixels may include a plurality of transistors, a light emitting element electrically coupled to the transistors, and a capacitor. The transistors may generate driving current based on signals provided through signal lines. The light emitting element may emit light according to the driving current.

To enhance the driving efficiency of the display device, the power consumption of the display device may be reduced in various manners. For example, the power consumption of the display device may be reduced by decreasing a driving frequency (or a data writing frequency) for displaying a static image. However, in a case where the display device displays an image in a low driving frequency, leakage of driving current may occur in a pixel, and flickering or the like of the displayed image may be discerned.

SUMMARY

Various embodiments of the present disclosure are directed to a display device in which the value of a reference voltage to be supplied to a pixel is adjusted based on variation in driving frequency and a representative grayscale of a frame.

Various embodiments of the present disclosure are directed to a method of driving a display device in which the value of a reference voltage to be supplied to a pixel is adjusted depending on variation in driving frequency and a representative grayscale of a frame.

However, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit and scope of the present disclosure.

According to an embodiment of the present disclosure, a display device includes: a pixel configured to display an image based on image data and a reference voltage; a controller configured to generate reference voltage data corresponding to the reference voltage for restraining leakage current in the pixel based on a frame frequency; and a power supply configured to generate the reference voltage based on the reference voltage data and supply the reference voltage to the pixel.

In an embodiment, the controller may determine the reference voltage data with further reference to a representative value of a grayscale of the image data.

In an embodiment, the representative value may be an average of grayscales included in the image data of a frame.

In an embodiment, for the representative value being the same, the reference voltage may change as the frame frequency changes from a first frequency to a second frequency.

In an embodiment, for the frame frequency being the same, the reference voltage may change as the representative value changes from a first value to a second value.

In an embodiment, the controller may include: a frequency analyzer configured to determine the frame frequency based on at least one of a vertical synchronization signal and a data enable signal supplied from an external device; a representative value determiner configured to determine the representative value based on grayscales included in the image data; and a voltage data generator configured to generate the reference voltage data with reference to a lookup table that stores values of the reference voltage corresponding to the frame frequency and the grayscale.

In an embodiment, the voltage data generator may include: a comparator configured to compare the frame frequency and a reference frequency; and a data determiner configured to determine the reference voltage data based on a result of comparison of the comparator.

In an embodiment, for the frame frequency being equal to or greater than the reference frequency, the data determiner may output a default value of the reference voltage data corresponding to a default value among the values of the reference voltage. For the frame frequency being less than the reference frequency, the data determiner may determine the reference voltage data with reference to the lookup table.

In an embodiment, the data determiner may extract a plurality of reference values from the lookup table based on the frame frequency and the representative value, and calculate the reference voltage data by interpolating the reference values.

In an embodiment, the controller may further include a register configured to output a compensation factor in which a distribution of threshold voltages of a driving transistor of the pixel is reflected. The power supply may output the reference voltage based on the reference voltage data and the compensation factor.

In an embodiment, the power supply may include a variable resistor circuit configured to adjust a resistance value based on the reference voltage data, and change an input power voltage based on the resistance value.

In an embodiment, the display device may further include: a data driver configured to supply a data voltage to the pixel through a data line based on the image data; a scan driver configured to supply a first scan signal to the pixel through a first scan line, supply a second scan signal to a second scan line; and an emission driver configured to supply a first emission control signal to the pixel through a first emission control line. The pixel may include: a light emitting element; a first transistor configured to control driving current based on a voltage of a first node and being coupled between a second node and a third node; a second transistor coupled between the data line and the second node, and configured to be turned on by the first scan signal supplied to the first scan line; a third transistor and a fourth transistor coupled in series between the first node and the third node and configured to be turned on by the second scan signal supplied to the second scan line; a fifth transistor configured to supply the reference voltage to a fourth node between the third transistor and the fourth transistor and to be turned off by the first emission control signal supplied to the first emission control line; and a sixth transistor coupled between a first power supply voltage and the second node and configured to be turned off by the first emission control signal.

In an embodiment, the scan driver may be further configured to supply a third scan signal to the pixel through a third scan line and supply a fourth scan signal to the pixel through a fourth scan line, and wherein the pixel may further include: a seventh transistor coupled between the third node and the light emitting element, and configured to be turned off by the first emission control signal; an eighth transistor configured to supply an initialization voltage to the light emitting element and to be turned on by the third scan signal supplied to the third scan line; a ninth transistor and a tenth transistor coupled in series between the first node and a power line for supplying the initialization voltage, and configured to be turned on by the fourth scan signal supplied to the fourth scan line; and an eleventh transistor configured to supply the reference voltage to a fifth node between the ninth transistor and the tenth transistor, and to be turned off by the first emission control signal.

In an embodiment, an identical scan signal may be supplied to the first scan line and the second scan line.

In an embodiment, the scan driver may be further configured to supply a third scan signal to the pixel through a third scan line, the emission driver may be further configured to supply a second emission control signal to the pixel through a second emission control line, and the pixel may further include: a seventh transistor coupled between the third node and the light emitting element, and configured to be turned off by the second emission control signal supplied to the second emission control line; and an eighth transistor configured to supply an initialization voltage to the third node and to be turned on by the third scan signal supplied to the third scan line.

In an embodiment, the second emission control signal may be supplied later than the first emission control signal.

In an embodiment, a first frequency at which the first scan signal is supplied to the first scan line may be equal to the frame frequency. A second frequency at which the first emission control signal is supplied to the first emission control line may be greater than the frame frequency.

According to an embodiment of the present disclosure, a method of driving a display device includes: determining a frame frequency based on at least one of a data enable signal and a vertical synchronization signal; determining, based on grayscales included in image data of a frame, a representative value of a grayscale of the frame; generating reference voltage data corresponding to a reference voltage based on the frame frequency and the representative value; and supplying, to a pixel, the reference voltage for restraining leakage current in the pixel based on the reference voltage.

In an embodiment, for the representative value of the image data being the same, the reference voltage may change as the frame frequency changes from a first frequency to a second frequency.

In an embodiment, generating the reference voltage data may include: comparing the frame frequency and a reference frequency; outputting a default value of the reference voltage data regardless of the frame frequency and the representative value for the frame frequency being equal to or greater than the reference frequency; and calculating the reference voltage data corresponding to the frame frequency and the representative value with reference to a lookup table for the frame frequency being less than the reference frequency.

Since the value of a reference voltage may be controlled based on the frame frequency and the representative value of a grayscale of a corresponding frame, the display device may minimize leakage current in the pixel and mitigate image flicker by controlling the reference voltage in response to variation in the frame frequency.

Furthermore, since leakage current may be minimized depending on the frame frequency, the display device may display a static image at a very low frequency. Hence, the display device may implement a reliable low-power driving operation while reducing the power consumption.

However, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit and scope of the present disclosure.

