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US-12628497-B2 - Display device

US12628497B2US 12628497 B2US12628497 B2US 12628497B2US-12628497-B2

Abstract

A display device having a display panel, a polarization film disposed on the display panel, and a plurality of retardation films disposed on the polarization film. Each of the plurality of retardation films has different in-plane phase differences R in , and the in-plane phase difference R in of each of the plurality of retardation films is 10000 nm or larger. According to an example embodiment, a color distortion, such as color irregularity, a color shift, and interference colors, is improved and the visibility of the rainbow stain is minimized or reduced.

Inventors

  • Suk Choi
  • Kyunghwan Oh
  • Kyungmin YEO

Assignees

  • LG DISPLAY CO., LTD.

Dates

Publication Date
20260512
Application Date
20220927
Priority Date
20211208

Claims (15)

  1. 1 . A display device, comprising: a display panel; a polarization film disposed on the display panel; and a plurality of retardation films disposed on the polarization film, wherein an in-plane phase difference R in of each of the plurality of retardation films is different, wherein the in-plane phase difference R in of each of the plurality of retardation films is 10000 nm or larger, wherein the plurality of retardation films includes a first retardation film and a second retardation film, an in-plane phase difference R in of the first retardation film is 10000 nm to 15000 nm, and an in-plane phase difference R in of the second retardation film is 20000 nm to 23000 nm.
  2. 2 . The display device according to claim 1 , wherein an optical axis of the first retardation film and an optical axis of the second retardation film are arranged at 90±10°.
  3. 3 . The display device according to claim 2 , wherein the optical axis of the first retardation film and an optical axis of the polarization film are arranged at 45±10° or 135±10° and the optical axis of the second retardation film and the optical axis of the polarization film are arranged at 45±10° or 135±10°.
  4. 4 . The display device according to claim 3 , wherein the optical axis of the first retardation film and the optical axis of the polarization film are arranged at 45±10°, and the optical axis of the second retardation film and the optical axis of the polarization film are arranged at 135±10°.
  5. 5 . The display device according to claim 3 , wherein the optical axis of the first retardation film and the optical axis of the polarization film are arranged at 135±10°, and the optical axis of the second retardation film and the optical axis of the polarization film are arranged at 45±10°.
  6. 6 . The display device according to claim 1 , wherein each of the plurality of retardation films has a thickness direction phase difference R th , and the thickness direction phase difference R th is 0.5 times or less of the in-plane phase difference R in .
  7. 7 . The display device according to claim 1 , further comprising: a support film disposed between the polarization film and the plurality of retardation films, or above the plurality of retardation films, or between the first retardation film and the second retardation film.
  8. 8 . The display device according to claim 7 , wherein the support film is disposed on the polarization film, the second retardation film is disposed between the polarization film and the support film, and the first retardation film is disposed on the support film.
  9. 9 . The display device according to claim 7 , wherein the support film is disposed on the polarization film, the first retardation film is disposed on the support film, and the second retardation film is disposed on the first retardation film.
  10. 10 . The display device according to claim 7 , wherein the support film is disposed between the polarization film and the plurality of retardation films.
  11. 11 . The display device according to claim 7 , wherein the support film is disposed between the first retardation film and the second retardation film.
  12. 12 . The display device according to claim 1 , further comprising a support film disposed on the plurality of retardation films, wherein a surface of the support film facing away from the plurality of retardation films also faces away from the display panel.
  13. 13 . The display device according to claim 1 , wherein a thickness of each of the plurality of retardation films is 30 μm to 120 μm.
  14. 14 . The display device according to claim 1 , wherein each of the plurality of retardation films includes at least one of polyethylene terephthalate, polyethersulfone, polycarbonate, polyimide, polypropylene, cycloolefin polymer, cycloolefin copolymer, and polymethylmethacrylate.
  15. 15 . The display device according to claim 1 , wherein each of the plurality of retardation films has a storage modulus of 10 6 Pa to 10 9 Pa and a Poisson ratio of 0.30 to 0.43.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of and the priority to Korean Patent Application No. 10-2021-0174895 filed on Dec. 8, 2021, in the Korean Intellectual Property Office. The disclosure of Korean Patent Application No. 10-2021-0174895 is incorporated by reference as if fully set forth herein. BACKGROUND 1. Technical Field The present disclosure relates to a display device, and more particularly, to a display device which may have a reduced rainbow stain to lead to excellent display quality. The display device may be easily implemented as a flexible display device. 2. Description of the Related Art In an information era, a display field involving expressing electrical information signals visually develops rapidly. In response to this, various display devices having excellent features, such as thin-thickness, light weight, and low power consumption, have been developed. Specific examples of such a display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an organic light emitting display device (OLED). Among the various display devices, an organic light emitting display device may not require a separate light source. Therefore, the organic light emitting display device may be manufactured as a light weight and thin device. The organic light emitting display device may be manufactured easily, and may have a low power consumption due to the low voltage driving. The organic light emitting display device may include a self-emitting element and layers formed of organic thin films so that the flexibility and elasticity may be superior to the other display devices and facilitate the implementation as a flexible display device. Generally, in the organic light emitting display device, in order to suppress the degradation of the visibility and the contrast ratio due to external light which may be incident on the display device, a polarization film may be disposed on the display panel and a protective film may be disposed to protect the polarization film. SUMMARY In the display device of the related art, a polyethylene terephthalate (PET) film may be mainly laminated on the polarization film to protect the polarization film. The PET film is inexpensive and has an excellent durability, but has a birefringence characteristic such that when the PET film is used as the protective film, there may be a problem in that the display quality may be degraded due to an optical distortion. In order to reduce the optical distortion, a high retardation film known as a stretched PET film or a super retardation film (SFR) may be laminated on the polarization film. However, in this case, when the user wears polarized sunglasses and views an image of the display device, rainbow stains are visible such that the display quality may be degraded (so-called “rainbow effect”). Accordingly, an object to be achieved by the present disclosure is to provide a display device that is capable of having an excellent display quality by minimizing or reducing visibility of a rainbow stain. Further, an object of the present disclosure is to provide a display device that may have an excellent folding reliability while maintaining a high display quality to be implemented as various flexible display devices such as a foldable display device or a rollable display device. Objects of the present disclosure are not limited to the above-mentioned objects. Other objects, which are not mentioned above, can be clearly understood by those skilled in the art from the following disclosure. According to an aspect of the present disclosure, a display device may include a display panel, a polarization film disposed on the display panel, a plurality of retardation films disposed on the polarization film, where an in-plane phase difference Rin of each of the plurality of retardation films is different, and where the in-plane phase difference Rin of each of the plurality of retardation films is 10000 nm or larger. Other details of the example embodiments are included in the detailed description and the drawings. According to an example embodiment of the present disclosure, a color distortion, such as color irregularity, a color shift, and interference colors, may improve and the visibility of the rainbow stain may be minimized or reduced. According to an example embodiment of the present disclosure, the rainbow stain may not be visible from the front and at a lateral viewing angle so that a display device may have an excellent display quality. Further, according to an example embodiment of the present disclosure, a folding reliability may be ensured with the excellent display quality so that various types of flexible display device may be implemented. The effects according to the present disclosure are not limited to the contents exemplified above. More effects are disclosed in the following sections. BRIEF DESCRIPTION OF THE DRAWINGS The above and othe