FLAT PANEL DISPLAY EMBEDDING OPTICAL IMAGING SENSOR

• US 20170315293A1
• Filed: 04/28/2017
• Published: 11/02/2017
• Est. Priority Date: 04/29/2016
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: BANG, Hyungseok, KIM, Cheolse, LEE, Buyeol
• Granted Patent: US 10,564,350 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/002 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
• CPC Class Codes: G02B 6/0035 provided on the surface of the light guide or in the bulk of it
• CPC Class Codes: G02B 6/102 for infrared and ultraviolet radiation
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop
• CPC Class Codes: H10K 59/65 OLEDs integrated with inorganic image sensors

Abstract

The present disclosure relates to a flat panel display embedding an optical imaging sensor such as a fingerprint image sensor. The present disclosure suggests a flat panel display embedding an image sensor comprising: a display panel including a display area and a non-display area; and a directional optical unit having a length and a width corresponding to the display panel and a thickness, and attached on a top surface of the display panel, wherein the directional optical unit provides a sensing light to the display area, and wherein the sensing light is collimated and directionized to a predetermined direction.

Claims

1. A flat panel display embedding an image sensor, comprising:

a display panel including a display area and a non-display area, the display panel having a top surface; and

a directional optical unit attached to the top surface of the display panel, the directional optical unit having a length along a length axis of the display panel, a width along a width axis of the display panel and a thickness along a thickness axis of the display panel,

wherein the directional optical unit provides a sensing light to the display area, and

wherein the sensing light is collimated and directionized along a predetermined direction.

2. The flat panel display according to claim 1, wherein the directional optical unit includes:

a cover plate having a size corresponding to the length and the width of the directional optical unit;

a light radiating film corresponding to the display area, the light radiating film positioned under the cover plate;

a light incident film positioned under the cover plate and disposed outside of the display area adjacent to a lateral side of the light radiating film;

a low refractive layer disposed under the light radiating film and the light incident film, the low refractive layer attached on the top surface of the display panel, and having a refractive index that is lower than a refractive index of the cover plate and that is lower than a refractive index of the light radiating film; and

a light source positioned under the light incident film.

3. The flat panel display according to claim 2, wherein the light source provides an incident light to an incident point on a surface of the light incident film;

wherein the light incident film includes a first holographic pattern that converts the incident light to a propagating light having an incident angle satisfying an internal total reflection condition of the cover plate, and that transmits the propagating light to the cover plate; and

wherein the light radiating film includes a second holographic pattern that converts a first portion of the propagating light into the sensing light, the sensing light having a reflection angle that satisfies a total reflection condition at a top surface of the cover plate and that satisfies a transmitting condition through the low refractive layer.

4. The flat panel display according to claim 3, wherein the propagating light has an expanding angle on a horizontal plane including the length axis and the width axis, and the propagating light maintains the collimated state on a vertical plane including the length axis and the thickness axis;

wherein the incident angle is larger than an internal total reflection critical angle at a first interface between the light radiating film and the low refractive layer; and

wherein the reflection angle is larger than a total reflection critical angle at a second interface between the cover plate and an air layer, and smaller than the internal total reflection critical angle at the first interface between the light radiating film and the low refractive layer.

5. The flat panel display according to claim 4, wherein the expanding angle is equal to or greater than an inner angle between a first line and a second line, the first line is a straight line between the incident point and a first end of a side of the cover plate opposite to the light incident film, and the second line is a straight line between the incident point and a second end of the side of the cover plate opposite to the light incident film.

6. The flat panel display according to claim 4, wherein the directional optical unit further includes:

a horizontal collimating film disposed under the cover plate between the light incident film and the light radiating film, the horizontal collimating film having a width corresponding to the width of the directional optical unit,

wherein the expanding angle is equal to or greater than an inner angle between a first line and a second line, the first line is a straight line between the incident point and a first end of a side of the horizontal collimating film opposite to the light incident film, and the second line is a straight line between the incident point and a second end of the side of the horizontal collimating film opposite to the light incident film, and

wherein the horizontal collimating film includes a third holographic pattern that horizontally collimates the propagating light having the expanding angle on the horizontal plane to correspond to the width.

7. The flat panel display according to claim 4, wherein the directional optical unit further includes:

a horizontal collimating film disposed in the non-display area at an opposite side of the cover plate facing the light incident film,

wherein the light incident film includes a third holographic pattern that converts the incident light to a total reflecting light having a total reflection angle different from the incident angle, and that transmits the total reflecting light to the cover plate,

wherein the expanding angle is equal to or greater than an inner angle between a first line and a second line, the first line is a straight line between the incident point and a first end of a side of the horizontal collimating film, and the second line is a straight line between the incident point and a second end of the side of the horizontal collimating film, the second end being opposite to the first end,

wherein the horizontal collimating film includes a fourth holographic pattern that horizontally collimates the propagating light having the expanding angle on the horizontal plane to correspond to the width, and that converts the total reflecting light to the propagating light and transmits the propagating light to the light incident film, and

wherein the second holographic pattern of the light radiating film is for transmitting the total reflecting light through.

8. The flat panel display according to claim 7, wherein the horizontal collimating film is disposed on at least one of a bottom surface of the cover plate and an upper surface of the display panel.

9. The flat panel display according to claim 2, wherein the light source provides a collimated light having a circular cross-sectional shape.

10. The flat panel display according to claim 9, wherein the light source includes at least two unit light sources disposed with a predetermined distance between them along the length direction.

11. The flat panel display according to claim 9, wherein the light source includes an ellipse cross-sectional shape having a first axis corresponding to the width direction and a second axis corresponding to the length direction,

wherein a ratio of a first dimension of the ellipse along the first axis to a second dimension of the ellipse along the second axis is within a range of 1:

2, inclusive, to 1;

4, inclusive.

12. A flat panel display with an embedded image sensor, comprising:

a display panel including a display area and a non-display area, the display panel having a first surface; and

a directional optical unit attached to the first surface of the display panel, the directional optical unit including;

a cover plate that covers the display panel, at least a portion of the cover plate extends beyond a first side of the display panel;

a collimated light source positioned adjacent to the first side of the display panel, the light source faces the portion of the cover plate that extends beyond the first side of the display panel;

a light incident film attached to the portion of the cover plate that extends beyond the first side of the display panel, the light incident film being positioned between the light source and the cover plate, the light incident film converts incident light received from the light source to a propagating light having an incident angle that satisfies an internal total reflection condition of the cover plate and transmits the propagating light into the cover plate;

a light radiating film attached to the cover plate and positioned between the cover plate and the display panel, the light radiating film receives the propagating light and converts a first portion of the propagating light into a sensing light, the sensing light having a reflection angle that satisfies a total reflection condition at a surface of the cover plate opposite to the light radiating film and that satisfies a transmitting condition through the low refractive layer; and

a low refractive layer attached to the light radiating film and the light incident film, the low refractive layer positioned between the light radiating film and the display panel and between the light incident film and the light source, the low refractive layer having a refractive index that is lower than a refractive index of the cover plate and that is lower than a refractive index of the light radiating film.

13. The flat panel display with an embedded image sensor according to claim 12, wherein the light source provides the incident light to an incident point on the light incident film.

14. The flat panel display with an embedded image sensor according to claim 13, wherein the light incident film includes a first holographic pattern that converts the incident light to the propagating light and transmits the propagating light to the cover plate, and the light radiating film includes a second holographic pattern that converts the first portion of the propagating light into the sensing light.