Display panel

Abstract

A display panel comprises a first substrate, a second substrate and a plurality of pixel units, and each pixel unit comprises a light-emitting element, an optical layer, a microstructure layer and a low refractive index layer. The light-emitting element is disposed on the inner surface of the first substrate. The optical layer covers the light-emitting element. The microstructure layer is disposed on a top surface of the optical layer away from the inner surface of the first substrate. The low refractive index layer is disposed between the second substrate and the microstructure layer. The refractive index of the low refractive index layer is smaller than the refractive index of the microstructure layer and the refractive index of the second substrate.

Description

Technical Field

[0001] The invention relates to a display device, and in particular to a display panel. Background Art

[0002] The display panel includes a plurality of layer structures. Before emitting light from the display panel, light may be reflected between the layer structures, causing undesirable phenomena such as a halo effect, thereby reducing display quality. Summary of the invention

[0003] The present invention provides a display panel which can avoid undesirable phenomena such as halo effect and has high light extraction efficiency.

[0004] According to one embodiment of the present invention, a display panel is provided, comprising a first substrate, a second substrate, and a plurality of pixel units between the first substrate and the second substrate, each pixel unit comprising a light-emitting element, an optical layer, a microstructure layer, and a low refractive index layer. The light-emitting element is disposed on the inner surface of the first substrate. The optical layer covers the light-emitting element. The microstructure layer is disposed on the top surface of the optical layer away from the inner surface. The low refractive index layer is disposed between the second substrate and the microstructure layer. The refractive index of the low refractive index layer is less than the refractive index of the microstructure layer and the refractive index of the second substrate.

[0005] Based on the above, the display panel provided by the embodiment of the present invention is configured with a low refractive index layer and a microstructure layer, the low refractive index layer is located between the upper substrate and the microstructure layer, and the refractive index of the low refractive index layer is less than the refractive index of the upper substrate and the refractive index of the microstructure layer. Accordingly, the recovery rate of large-angle light, the transmittance of the low refractive index layer and the transmittance of the upper substrate are improved, and the forward light output of the display panel is improved.

[0006] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 , Figure 2 , Figure 3 , Figure 4A , Figure 5A Schematic diagrams showing display panels according to various embodiments of the present invention.

[0008] Figure 4B as well as Figure 5B Shown separately Figure 4A as well as Figure 5A A partial enlarged view of .

[0009] The reference numerals are described as follows:

[0010] 1, 2, 3, 4, 5: Display panel

[0011] 10: Pixel unit

[0012] 30: Dike structure

[0013] 100: Low refractive index layer

[0014] 101: First low refractive index layer

[0015] 102: Second low refractive index layer

[0016] 200: Microstructure layer

[0017] 300: Optical layer

[0018] 301: Transparent layer, scattering layer

[0019] 302: Color transfer layer

[0020] 400: Light emitting element

[0021] h1, h2: height

[0022] d1, d2: width

[0023] S1: First substrate

[0024] S2: Second substrate DETAILED DESCRIPTION

[0025] Reference Figure 1 , which is a schematic diagram of a display panel according to an embodiment of the present invention.

[0026] The display panel 1 includes a first substrate S1, a second substrate S2, and a plurality of pixel units 10 and a plurality of embankment structures 30 between the first substrate S1 and the second substrate S2. The embankment structures 30 are respectively disposed between the adjacent pixel units 10. Each pixel unit 10 includes a light emitting element 400, an optical layer 300, a microstructure layer 200, and a low refractive index layer 100.

[0027] The light-emitting element 400 is disposed on the inner surface of the first substrate S1 facing the second substrate S2, and is, for example, an electroluminescent element, such as a light-emitting diode and an organic light-emitting diode, but is not limited thereto. The optical layer 300 covers the light-emitting element 400, and may be, for example, a transparent layer 301 (or a scattering layer 301) and a color conversion layer 302. The microstructure layer 200 is disposed on the top surface of the optical layer 300, and includes a plurality of microstructures protruding in a direction away from the optical layer 300. The distance between the top surface of the microstructure layer 200 and the first substrate S1 is smaller than the distance between the top surface of the corresponding embankment structure 30 and the first substrate S1. The low refractive index layer 100 is disposed between the second substrate S2 and the microstructure layer 200.

[0028] It should be particularly noted that the refractive index of the low refractive index layer 100 is configured to be smaller than the refractive index of the microstructure layer 200 and smaller than the refractive index of the second substrate S2. Since the refractive index of the low refractive index layer 100 is smaller than the refractive index of the microstructure layer 200, and the top surface of the microstructure layer 200 is lower than the top surface of the corresponding embankment structure 30, for some light emitted by the light emitting element 400, if total reflection occurs at the interface between the microstructure layer 200 and the low refractive index layer 100, these light rays can be reflected back to the optical layer 300 until they penetrate the interface between the microstructure layer 200 and the low refractive index layer 100 at an angle smaller than the total reflection angle. In addition, since the light penetrating the interface between the microstructure layer 200 and the low refractive index layer 100 is incident on the low refractive index layer 100 at an angle smaller than the total reflection angle of the interface, and the refractive index of the low refractive index layer 100 is smaller than the refractive index of the second substrate S2, total reflection will not occur at the interface between the low refractive index layer 100 and the second substrate S2. Accordingly, light loss can be avoided and the current efficiency of the display panel 1 can be improved.

[0029] The second substrate S2 is the upper substrate of the display panel 1. In some preferred embodiments, the refractive index of the low refractive index layer 100 is configured to fall within the range of 1.0 to 1.2, or within the range of 1.0 to 1.1. In some embodiments, the low refractive index layer 100 is, for example, a vacuum layer and a dielectric layer, wherein the dielectric layer may, for example, include an air layer. Since the refractive index of the low refractive index layer 100 is close to the refractive index of the air above the second substrate S2 (approximately 1.0), the light entering the second substrate S2 can penetrate the top surface of the second substrate S2 away from the first substrate S1, and will not be totally reflected on the top surface of the second substrate S2. It can avoid light loss and further improve the current efficiency of the display panel 1.

[0030] In order to fully illustrate the various embodiments of the present invention, other embodiments of the present invention will be described below. It must be noted that the following embodiments use the component numbers and some contents of the previous embodiments, wherein the same numbers are used to represent the same or similar components, and the description of the same technical contents is omitted. For the description of the omitted parts, please refer to the previous embodiments, and the following embodiments will not be repeated.

[0031] Reference Figure 2 , which is a schematic diagram of a display panel according to an embodiment of the present invention.

[0032] The display panel 2 of this embodiment has substantially the same structure as the display panel 1. The display panel 2 is different from the display panel 1 in that the low refractive index layer 100 includes a first low refractive index layer 101 and a second low refractive index layer 102. The first low refractive index layer 101 is disposed between the microstructure layer 200 and the second low refractive index layer 102, and the refractive index of the first low refractive index layer 101 is less than the refractive index of the second low refractive index layer 102.

[0033] In detail, the refractive index of the first low refractive index layer 101 and the second low refractive index layer 102 are both lower than the refractive index of the microstructure layer 200 and the refractive index of the second substrate S2. For example, in some embodiments, the refractive index of the microstructure layer 200 and the refractive index of the second substrate S2 are about 1.5, the refractive index of the first low refractive index layer 101 is within the range of 1.0 to 1.2, and the refractive index of the second low refractive index layer is within the range of 1.2 to 1.4.

[0034] Since the refractive index of the first low refractive index layer 101 is lower than the refractive index of the microstructure layer 200, and the top surface of the microstructure layer 200 is lower than the top surface of the corresponding embankment structure 30, for some light emitted by the light emitting element 400, if total reflection occurs at the interface between the microstructure layer 200 and the first low refractive index layer 101, these light rays can be reflected back to the optical layer 300 until they penetrate the interface between the microstructure layer 200 and the first low refractive index layer 101 at an angle less than the total reflection angle. In addition, since the light penetrating the interface between the microstructure layer 200 and the first low refractive index layer 101 is incident on the first low refractive index layer 101 at an angle less than the total reflection angle of the interface, the refractive index of the first low refractive index layer 101 is less than the refractive index of the second low refractive index layer 102, and the refractive index of the second low refractive index layer 102 is less than the refractive index of the second substrate S2, total reflection does not occur at the interface between the first low refractive index layer 101 and the second low refractive index layer 102 and the interface between the second low refractive index layer 102 and the second substrate S2. Accordingly, light loss can be avoided and the current efficiency of the display panel 2 can be improved.

[0035] In addition, since the refractive index of the first low refractive index layer 101, the refractive index of the second low refractive index layer 102 and the refractive index of the second substrate S2 gradually increase, the reflectivity at the interface between these layers or elements will be reduced, thereby improving the transmittance, avoiding light loss, and improving the current efficiency of the display panel 2.

[0036] Reference Figure 3 , which shows a schematic diagram of a display panel according to an embodiment of the present invention. The display panel 3 of this embodiment has substantially the same structure as the display panel 1, which is not described in detail here. In the display panel 3, the microstructure layer 200 includes a curved surface protruding in a direction away from the optical layer 300, thereby reducing the probability of total reflection occurring at the interface between the microstructure layer 200 and the low refractive index layer 100, thereby improving the current efficiency of the display panel 3.

[0037] Reference Figure 4A as well as Figure 4B , Figure 4A A schematic diagram showing a display panel according to an embodiment of the present invention is shown. Figure 4B Show Figure 4AA partial enlarged view. The display panel 4 of this embodiment has substantially the same structure as the display panel 1, which will not be described in detail here. The display panel 4 is different from the display panel 1 in that, in the display panel 1, the microstructure layer 200 includes a plurality of microcolumn structures protruding in a direction away from the optical layer 300; and in the display panel 4, the microstructure layer 200 includes a plurality of microprism structures protruding in a direction away from the optical layer 300. Accordingly, the probability of total reflection occurring at the interface between the microstructure layer 200 and the low refractive index layer 100 can be reduced, thereby improving the current efficiency of the display panel 1 and the display panel 4. In addition, refer to Figure 4B In a preferred embodiment, the height h1 of each micro-prismatic structure in the direction away from the optical layer 300 is configured to be greater than or equal to its width d1, thereby increasing the slope of the side of the micro-prismatic structure, further reducing the probability of total reflection, and improving the current efficiency of the display panel 4.

[0038] Reference Figure 5A as well as Figure 5B , Figure 5A A schematic diagram showing a display panel according to an embodiment of the present invention is shown. Figure 5B Show Figure 5A The display panel 5 of this embodiment has substantially the same structure as the display panel 1, which will not be described in detail. In the display panel 5, the microstructure layer 200 includes a plurality of microlens structures protruding in a direction away from the optical layer 300. Accordingly, the probability of total reflection occurring at the interface between the microstructure layer 200 and the low refractive index layer 100 can be reduced, thereby improving the current efficiency of the display panel 5. In addition, referring to Figure 5B In a preferred embodiment, the height h2 of each microlens structure in the direction away from the optical layer 300 is configured to be greater than or equal to its width d2, thereby further reducing the probability of total reflection and improving the current efficiency of the display panel 5.

[0039] It should be noted that, compared to a comparative example in which the low refractive index layer 100 is not configured between the microstructure layer 200 and the second substrate S2, the display panel 5 provided in this embodiment utilizes the refractive index difference between the microstructure layer 200 and the low refractive index layer 100 to improve the recovery rate of large-angle light, as well as the transmittance of the low refractive index layer 100 and the second substrate S2, thereby obtaining a gain of 26.2% in the forward light output. Further, compared to another comparative example in which the low refractive index layer 100 is provided but the microstructure layer 200 is not provided, the display panel 5 provided in this embodiment also obtains a gain of 13.3% in the forward light output.

[0040] In summary, the display panel provided by the embodiment of the present invention is configured with a low refractive index layer and a microstructure layer, the low refractive index layer is located between the upper substrate and the microstructure layer, and the refractive index of the low refractive index layer is less than the refractive index of the upper substrate and the refractive index of the microstructure layer. Accordingly, the recovery rate of large-angle light, the transmittance of the low refractive index layer and the transmittance of the upper substrate are improved, and the forward light output of the display panel is improved.

Claims

1. A display panel, comprising a first substrate, a second substrate, and a plurality of pixel units between the first substrate and the second substrate, each of the pixel units comprising: A light emitting element is disposed on the inner surface of the first substrate; An optical layer, covering the light emitting element; A microstructure layer is disposed on the top surface of the optical layer away from the inner surface; as well as A low refractive index layer is disposed between the second substrate and the microstructure layer. The refractive index of the low refractive index layer is smaller than the refractive index of the microstructure layer and the refractive index of the second substrate.

2. The display panel as described in claim 1 further includes a plurality of embankment structures, respectively arranged between adjacent plurality of pixel units, and the distance between the top surface of the microstructure layer of each pixel unit and the first substrate is smaller than the distance between the top surface of the plurality of embankment structures and the first substrate. 3 . The display panel according to claim 1 , wherein the refractive index of the low refractive index layer falls within a range of 1.0 to 1.

2. The display panel as claimed in claim 3 , wherein the low refractive index layer directly contacts the second substrate and the microstructure layer. The display panel as claimed in claim 3 , wherein the low refractive index layer is a vacuum layer or an air layer.

6. The display panel as described in claim 1, wherein the low refractive index layer comprises a first low refractive index layer and a second low refractive index layer, the first low refractive index layer is arranged between the microstructure layer and the second low refractive index layer, and the refractive index of the first low refractive index layer is less than the refractive index of the second low refractive index layer. 7 . The display panel of claim 6 , wherein the refractive index of the second low refractive index layer falls within a range of 1.2 to 1.

4. 8 . The display panel of claim 7 , wherein the refractive index of the first low refractive index layer falls within a range of 1.0 to 1.

2. 9 . The display panel of claim 6 , wherein the first low refractive index layer directly contacts the microstructure layer, and the second low refractive index layer directly contacts the second substrate. 10 . The display panel of claim 6 , wherein the refractive index of the first low-refractive-index layer, the refractive index of the second low-refractive-index layer, and the refractive index of the second substrate increase gradually. 11 . The display panel of claim 1 , wherein the microstructure layer comprises at least one protrusion protruding in a direction away from the optical layer, and a height of the at least one protrusion is greater than or equal to a width of the at least one protrusion.

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