Display device and mobile terminal including the same

1 . A display device, comprising:

a display panel including a first pixel area and a second pixel area adjacent to the first pixel area, the second pixel area including a plurality of sub-pixels and one or more light transmitting parts disposed between the plurality of sub-pixels;

a cover glass disposed on a first surface of the display panel and extending to cover the entire second pixel area;

an optical module disposed under a second surface of the display panel being opposite to the first surface of the display panel, the optical module including an emitter configured to emit infrared light which passes through one of the one or more light transmitting parts of the second pixel area; and

a diffractive optical element formed on at least one of a thin film layer of a circuit layer or at least one of a thin film layer of a light emitting element layer included in the display panel,

wherein the diffractive optical element is located within the cover glass and disposed only at a position corresponding to the one of the one or more light transmitting parts of the second pixel area though which the infrared light passes, and

wherein the diffractive optical element is configured to separate the infrared light from the optical module into a plurality of dot beams.

2 . The display device of claim 1 , wherein a PPI (Pixels Per Inch) of the second pixel area is less than a PPI of the first pixel area.

3 . The display device of claim 1 , wherein the optical module is a light source including the emitter for emitting the infrared light and a collimating lens disposed on the emitter of the light source.

4 . The display device of claim 3 , wherein the infrared light from the emitter of the light source is incident on the diffractive optical element at an angle substantially perpendicular to a plane of the display panel.

5 . The display device of claim 1 , wherein a plurality of diffractive optical elements are spaced apart by a predetermined interval and face the light transmitting parts correspondingly,

the optical module is a light source which includes the emitter and a plurality of other emitters each generating the infrared light, and

the emitter and the plurality of other emitters are disposed under the second surface of the display panel to face the light transmitting parts, respectively.

6 . The display device of claim 1 , wherein the diffractive optical element includes one or more hologram diffraction patterns.

7 . The display device of claim 6 , wherein the diffractive optical element covers a plurality of pixels and the light transmitting parts in the second pixel area,

the optical module is a light source which includes a plurality of emitters each generating the infrared light, and

the plurality of emitters are disposed under the second surface of the display panel to face the light transmitting parts, respectively.

8 . The display device of claim 6 , wherein the infrared light from the optical module is incident on the hologram diffraction pattern at an angle substantially perpendicular to a plane of the display panel.

9 . The display device of claim 6 , wherein a plurality of hologram diffractive patterns are spaced apart by a predetermined interval and face the light transmitting parts correspondingly,

the optical module is a light source which includes the emitter and a plurality of other emitters each generating infrared light, and

the emitter and the plurality of other emitters are disposed under the second surface of the display panel to face the light transmitting parts, respectively.

10 . The display device of claim 6 , wherein the hologram diffractive pattern covers one or more pixels and the one or more light transmitting parts in the second pixel area,

the optical module is a light source which includes a plurality of emitters each generating the infrared light, and

the plurality of emitters are disposed under the second surface of the display panel to face the light transmitting parts, respectively.

11 . The display device of any one of claim 1 , wherein the display panel further comprises:

a touch sensor layer disposed on the plurality of sub-pixels and the one or more light transmitting parts;

a polarizing plate disposed on the touch sensor layer and under the cover glass; and

a lens layer disposed between the touch sensor layer and the polarizing plate,

wherein the lens layer includes a collimating lens facing at least one of the one or more light transmitting parts.

12 . The display device of claim 1 , wherein the display panel further comprises a first reflector disposed on a substrate of the display panel under pixels of the second pixel area, and

the optical module is a light source which further includes a second reflector disposed under at least one of the one or more light transmitting parts and facing the first reflector.

13 . The display device of claim 12 , wherein the infrared light from the optical module is reflected by the first reflector, which is further reflected toward the one or more light transmitting parts by the second reflector.

14 . The display device of claim 1 , wherein the display panel further comprises:

a light collecting part configured to collect the infrared light from the optical module; and

a collimating part embedded in at least one of the one or more light transmitting parts between the diffractive optical element and the light collecting part, and configured to collimate the infrared light passing through the light collecting part to the diffractive optical element.

15 . The display device of claim 1 , wherein a boundary of the diffractive optical element located within the cover glass fully encompasses a boundary of the emitter disposed below the one of the one or more light transmitting parts of the second pixel area through which the infrared light passes.

16 . The display device of claim 1 , wherein the emitter configured to emit the infrared light, the one of the one or more light transmitting parts of the second pixel area through which the infrared light passes, and the diffractive optical element are vertically stacked in that order, and are substantially aligned with each other.

17 . A mobile terminal, comprising:

a display panel configured to display an input image, and including a first pixel area and a second pixel area, the second pixel area including a plurality of sub-pixels and one or more light transmitting parts disposed between the plurality of sub-pixels;

a display panel driver configured to write pixel data of the input image to pixels of the display panel;

a cover glass disposed on a front surface of the display panel and extending to cover the entire second pixel area;

a light source disposed under a rear surface of the display panel to face the second pixel area, and configured to generate infrared light which is to pass through one of the one or more light transmitting parts;

a diffractive optical element formed on at least one of a thin film layer of a circuit layer or at least one of a thin film layer of a light emitting element layer included in the display panel,

wherein the diffractive optical element is located within the cover glass and disposed only at a position facing the one of the one or more light transmitting parts of the second pixel area, the diffractive optical element configured to separate the infrared light from the light source into a plurality of dot beams;

an infrared camera disposed under the rear surface of the display panel, and configured to convert the infrared light incident through the display panel into an electrical signal to output facial pattern data; and

a host system configured to transmit the pixel data of the input image to the display panel driver, and process user authentication with respect to the facial pattern data received from the infrared camera.

18 . The mobile terminal of claim 17 , wherein a PPI (Pixels Per Inch) of the second pixel area is less than a PPI of the first pixel area.

19 . The mobile terminal of claim 17 , wherein the display panel further includes a first reflector disposed on a substrate of the display panel under pixels of the second pixel area, and

the light source includes a second reflector disposed under at least one of the one or more light transmitting parts and facing the first reflector.

20 . The mobile terminal of claim 17 , wherein a boundary of the diffractive optical element located within the cover glass fully encompasses a boundary of the light source disposed below the one of the one or more light transmitting parts through which the infrared light is to pass.

21 . The mobile terminal of claim 17 , wherein the light source configured to emit the infrared light, the one of the one or more light transmitting parts through which the infrared light is to pass, and the diffractive optical element are vertically stacked in that order, and are substantially aligned with each other.