CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0053096, filed on May 7, 2019, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

Technical Field

The present disclosure relates to a foldable display in which a screen is capable of being folded using a flexible display panel, and a driving method thereof.

Description of Related Art

Electroluminescent display devices are roughly classified into inorganic light emitting display devices and organic light emitting display devices according to materials of light emitting layers. Active matrix type organic light emitting display devices include organic light emitting diodes (hereinafter referred to as “OLEDs”), which emit light by themselves and have fast response speeds and advantages in which light emission efficiencies, brightness, and viewing angles are high. In the organic light emitting display devices, the OLEDs are formed in pixels. Since the organic light emitting display devices have fast response speeds and are excellent in light emission efficiency, brightness, and viewing angle as well as capable of exhibiting a black gray scale in a full black color, the organic light emitting display devices are excellent in a contrast ratio and color reproducibility.

The organic light emitting display devices do not require backlight units and may be implemented on a plastic substrate, a thin glass substrate, or a metal substrate, which is made of a flexible material. Therefore, flexible displays may be implemented as the organic light emitting display devices.

A screen size of the flexible display may be varied by winding, folding, and bending a flexible display panel. The flexible display may be implemented as a rollable display, a bendable display, a foldable display, a slidable display, or the like. The flexible display devices may be applied not only to mobile devices such as smartphones and tablet personal computers (PCs), but also to televisions (TVs), vehicle displays, and wearable devices, and application fields of the flexible display device are expanding.

The screen size of the foldable display may be varied by folding or unfolding a large screen. An information device employing a foldable display has a problem in that power consumption is greater than that of a conventional mobile device due to a large screen. For example, since a foldable phone employs a foldable display of 7 inches or more, a load of a display panel increases 5.7 times as compared to that of the existing smart phone, and thus power consumption increases largely. The increase in power consumption causes a reduction in battery lifetime. Consequently, the foldable phone requires a battery which is much larger in capacity than that of the existing smart phone.

SUMMARY OF THE INVENTION

The present disclosure is directed to solving all the above-described necessity and problems.

It should be noted that objects of the present disclosure are not limited to the above-described objects, and other objects of the present disclosure will be apparent to those skilled in the art from the following descriptions.

According to an aspect of the present disclosure, there is provided a foldable display including a flexible display panel having a screen in which data lines, to which data voltages are applied, cross gate lines to which a scan signal and a light emission control signal are applied, and pixels are disposed, and a display panel driver configured to activate an entirety of the screen of the flexible display panel and display an image on a maximum screen when the flexible display panel is unfolded in an unfolded state and activate a part of the screen when the flexible display panel is folded in a folded state to display the image on a screen that is smaller than the maximum screen and to display a black color on a deactivated screen.

The screen of the flexible display panel may at least include a first screen, a second screen, and a folding boundary which is located between the first screen and the second screen. The folding boundary is foldable.

Each of the pixels may include a light emitting element, a drive element (DT) disposed between a pixel drive voltage and the light emitting element and configured to supply a current to the light emitting element, a first switching element configured to switch or control a current path between the pixel drive voltage and the light emitting element in response to a light emission control signal, and a second switching element configured to apply an initialization voltage, which suppresses light emission of the light emitting element, to an anode of the light emitting element in response to a scan signal in the folded state.

According to another aspect of the present disclosure, there is provided a method of driving a foldable display, which includes activating an entirety of a screen (full portion of a screen) of a flexible display panel when the flexible display panel is in an unfolded state in which the screen is unfolded to display an image on a maximum screen (full screen) thereof, and activating a part of the maximum screen when the flexible display panel is in a folded state in which the screen is folded to display the image on a screen that is smaller than the maximum screen and display a black color on a deactivated screen.

