TWI831382B - Backlight module and display apparatus - Google Patents

Abstract

A backlight module and a display apparatus are provided. The backlight module includes a quantum fluorescent film. The quantum fluorescent film includes a light conversion layer. The light conversion layer includes a resin material, a plurality of quantum dots and a plurality of phosphors. The plurality of quantum dots and the plurality of phosphors are dispersed in the resin material.

Description

Backlight modules and display devices

The present invention relates to a light-emitting element, and in particular to a backlight module and a display device including a light conversion layer.

Quantum dots are extremely tiny semiconductor nanostructures that are invisible to the naked eye. When quantum dots are excited by light, they emit colored light, and the color of the emitted light is determined by the material, size, and shape of the quantum dots. In other words, the above-mentioned properties of quantum dots can change the color of the light emitted by the light source. Therefore, in recent years, light conversion layers containing quantum dots have been widely used in backlight modules and display devices.

The invention provides a backlight module containing a quantum fluorescent film, wherein the quantum fluorescent film includes a light conversion layer, and the light conversion layer includes a resin material and quantum dots and phosphors dispersed therein.

The backlight module of the present invention includes a quantum fluorescent film. The quantum fluorescent film includes a light conversion layer. The light conversion layer includes a resin material, a plurality of quantum dots and a plurality of phosphors. The plurality of quantum dots and the plurality of phosphors are dispersed in the resin material.

In an embodiment of the present invention, the backlight module further includes a light source and a light guide plate. The light source emits blue light. The light guide plate is optically coupled to the light source. The light conversion layer is disposed on the light exit surface of the light guide plate.

In an embodiment of the backlight module of the present invention, the light source is disposed adjacent to the side of the light guide plate to form an edge-lit structure.

In an embodiment of the backlight module of the present invention, the light source is disposed adjacent to the back side of the light guide plate to form a direct-lit structure.

In an embodiment of the backlight module of the present invention, the backlight module further includes a first base material and a second base material, wherein the light conversion layer is disposed between the first base material and the second base material.

In an embodiment of the backlight module of the present invention, the first base material includes a gas barrier layer.

In an embodiment of the backlight module of the present invention, the first base material does not include a gas barrier layer.

In an embodiment of the backlight module of the present invention, the second base material includes a gas barrier layer.

In an embodiment of the backlight module of the present invention, the second base material does not include a gas barrier layer.

In an embodiment of the backlight module of the present invention, the backlight module further includes an optical film disposed on the quantum fluorescent film.

In an embodiment of the backlight module of the present invention, the optical film includes a brightness enhancement film, a diffusion film, a polarizing film or a combination thereof.

In an embodiment of the backlight module of the present invention, the resin material includes acrylic resin, epoxy resin, silicone or a combination thereof.

In an embodiment of the backlight module of the present invention, the quantum dots have a core-gradient alloy layer-shell structure.

In an embodiment of the backlight module of the present invention, the core material of the quantum dots includes CdSe or InP.

In an embodiment of the backlight module of the present invention, the material of the quantum dot shell includes ZnSe or ZnS and a combination thereof.

In an embodiment of the backlight module of the present invention, the quantum dots include green quantum dots, red quantum dots or a combination thereof.

In an embodiment of the backlight module of the present invention, the phosphor includes green phosphor, red phosphor or a combination thereof.

In one embodiment of the backlight module of the present invention, the green phosphor material includes (Ba,Sr) ₂ SiO ₄ : Eu ²⁺ , Si _6-z Al _z O _z N _8-z : Eu ²⁺ , Al _1.7 O _2.1 N _0.3 : Mn ²⁺ , Eu ²⁺ or their combination.

In an embodiment of the backlight module of the present invention, the material of the red phosphor includes CaAlSiN ₃ : Eu ²⁺ , Sr ₂ Si ₅ N ₈ : Eu ²⁺ , K ₂ SiF ₆ : Mn ⁴⁺ or other materials thereof. combination.

The display device of the present invention includes a display panel and the aforementioned backlight module. The backlight module is disposed on one side of the display panel.

Based on the above, in the backlight module of the present invention, the light conversion layer contains a resin material and a plurality of quantum dots and a plurality of phosphors dispersed in the resin material. Therefore, the backlight module including the light conversion layer can have a wider color gamut and a lower cadmium content.

10, 20: Display device

100:Backlight module

102:Display panel

104, 204: Light guide plate

104a, 204a: light incident surface

104b, 204b: light-emitting surface

104c: Back

106:Light source

108:Quantum fluorescent film

110:Light conversion layer

110a: Resin material

110b:Quantum dots

110c:Fluorescent powder

112:First base material

114:Second base material

L: Blu-ray

FIG. 1 is a schematic cross-sectional view of a display device according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the quantum fluorescent film in the display device of FIG. 1 .

FIG. 3 is a schematic cross-sectional view of a display device according to a second embodiment of the present invention.

Figure 4 shows the white light emission spectra of the display devices of the experimental example and the comparative example.

Figure 5A is a color gamut diagram of Experimental Example 1.

FIG. 5B is a color gamut diagram of Comparative Example 1.

Examples are listed below and described in detail with reference to the drawings. However, the provided examples are not intended to limit the scope of the present invention. In addition, the drawings are for illustrative purposes only and are not drawn to original size. To facilitate understanding, the same elements will be identified with the same symbols in the following description.

The terms "include", "include", "have", etc. used in this article are all open terms, which means "including but not limited to".

When terms such as “first” and “second” are used to describe elements, they are only used to distinguish these elements from each other and do not limit the order or importance of these elements. Therefore, in some cases, a first element may also be termed a second element, and the second element may also be termed a first element, without departing from the scope of the invention.

In addition, the directional terms mentioned in the text, such as "up", "down", etc., are only used to refer to the direction of the drawings and are not used to limit the present invention. Therefore, it will be understood that "on" may be used interchangeably with "under" and that when an element such as a layer or film is placed "on" another element, the element may be placed directly on the other element, or there may be Intermediate components. On the other hand, when a component is said to be placed "directly on" another component, there are no intervening components between them.

FIG. 1 is a schematic cross-sectional view of a display device according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the quantum fluorescent film in the display device of FIG. 1 .

Referring to FIGS. 1 and 2 simultaneously, in this embodiment, the display device 10 includes a backlight module 100 and a display panel 102 . The backlight module 100 may include a light guide plate 104, a light source 106 and a quantum fluorescent film 108. The display panel 102 may be a liquid crystal panel. The detailed structure of the display panel 102 is well known to those skilled in the art and will not be described further here. The backlight module 100 is disposed on one side of the display panel 102 .

In this embodiment, the cross section of the light guide plate 104 is triangular. Specifically, in this embodiment, the light guide plate 104 has a light incident surface 104a, a light exit surface 104b and a back surface 104c. The angle between the light entrance surface 104a and the light exit surface 104b is a right angle, and the light exit surface 104b is opposite to the back surface 104c. , but the present invention is not limited to this. In other embodiments, the cross section of the light guide plate 104 may have other suitable shapes. In this embodiment, The light incident surface 104a can be regarded as the side surface of the light guide plate 104. The material of the light guide plate 104 may be glass, polymethylmethacrylate (PMMA), polycarbonate (PC), polyethylene terepthalate (PET), polyimide ( polyimide, PI) or other suitable materials. In addition, depending on actual requirements, a reflective layer (not shown) or other components may be provided on the back side of the light guide plate 104, which is not limited in the present invention.

In addition, in this embodiment, the light source 106 is disposed adjacent to the side surface (light incident surface 104a) of the light guide plate 104 to optically couple with the light guide plate 104 to form an edge-lit structure. In this way, the backlight module 100 is a well-known edge-lit backlight module. The light source 106 may be a light emitting diode (LED) or other suitable light emitting element, which is not limited in the present invention. In this embodiment, depending on the quantum fluorescent film 108 of the present invention, the light source 106 is a light-emitting element that emits blue light. After the blue light L emitted by the light source 106 enters the light guide plate 104 from the light incident surface 104a, it is transmitted inside the light guide plate 104 through total reflection, and is emitted from the light exit surface 104b to reach the quantum fluorescent film 108. The blue light L reaching the quantum fluorescent film 108 may be partially converted into red light and green light, so that the blue light L, red light and green light may be mixed into white light and transmitted to the display panel 102 .

In this embodiment, the quantum fluorescent film 108 is disposed on the light exit surface 104b of the light guide plate 104. The quantum fluorescent film 108 is in direct contact with the light exit surface 104b of the light guide plate 104, but the invention is not limited thereto. In other embodiments, other components may be provided between the quantum fluorescent film 108 and the light exit surface 104b of the light guide plate 104 depending on actual requirements. In other embodiments, depending on actual needs, the quantum fluorescent film 108 and the display panel can be Set other components between 102.

In this embodiment, the quantum fluorescent film 108 includes a light conversion layer 110, a first substrate 112 and a second substrate 114. The light conversion layer 110 is disposed between the first substrate 112 and the second substrate 114 . The first substrate 112 and the second substrate 114 may each be a polyethylene terephthalate substrate or other suitable substrate. In this embodiment, neither the first substrate 112 nor the second substrate 114 includes a gas barrier layer, but the invention is not limited thereto. In other embodiments, depending on actual requirements, the first substrate 112 and/or the second substrate 114 may include a gas barrier layer.

In addition, depending on actual requirements, in other embodiments, an optical film (not shown) may be disposed between the quantum fluorescent film 108 and the display panel 102 or between the quantum fluorescent film 108 and the light guide plate 104 . The optical film can be a brightness enhancing film, a diffusion film, a polarizing film or a combination thereof.

In this embodiment, the light conversion layer 110 includes a resin material 110a, a plurality of quantum dots 110b, and a plurality of phosphors 110c. The quantum dots 110b and the phosphor 110c are uniformly dispersed in the resin material 110a. The resin material 110a may be acrylic resin, epoxy resin, silicone or a combination thereof. Furthermore, in this embodiment, the quantum dot 110b has a core-gradient alloy-shell structure. The quantum dots 110b may be green quantum dots, red quantum dots, or a combination thereof. In the core-gradient alloy-shell structure, the core material can be CdSe or InP, and the shell material includes ZnSe or ZnS. In this embodiment, the phosphor 110c can be green phosphor, red phosphor or a combination thereof. The materials of green phosphor can be (Ba,Sr) ₂ SiO ₄ : Eu ²⁺ , Si _6-z Al _z O _z N _8-z : Eu ²⁺ , Al _1.7 O _2.1 N _0.3 : Mn ²⁺ , Eu ²⁺ or combination thereof. The material of the red phosphor can be CaAlSiN ₃ : Eu ²⁺ , Sr ₂ Si ₅ N ₈ : Eu ²⁺ , K ₂ SiF ₆ : Mn ⁴⁺ or a combination thereof.

In one embodiment, the quantum dots 110b are green quantum dots and the phosphor 110c is a red phosphor. When the blue light L enters the light conversion layer 110, the green quantum dots can be excited to emit green light, and the green quantum dots emitting green light can have a narrow half-width at half maximum (FWHM), so that the green quantum dots can be included in the light conversion layer 110. The backlight module 100 of the fluorescent film 108 can have a wider color gamut. For example, compared with a light conversion layer containing only yellow phosphor (Y ₃ Al ₅ O ₁₂ :Ce), the backlight module 100 including the quantum fluorescent film 108 can have a wider color gamut.

In addition, when the blue light L enters the light conversion layer 110, it can excite the red phosphor to emit red light, and the material of the red phosphor does not contain cadmium (Cd). Therefore, the quantum fluorescent film 108 can have a lower cadmium content, and the cadmium content can even be 0 ppm. Cadmium is one of the dangerous toxic heavy metals. Accumulation in the body can cause serious damage to the body and induce cancer. In order to protect the health of users and reduce environmental pollution, the EU's Restriction of Hazardous Substances (RoHS) directive limits the cadmium content of electrical and electronic equipment to less than 100 ppm. It is obvious that although the green quantum dots of the quantum fluorescent film 108 of this embodiment contain cadmium (the core of which is CdSe), compared with other general wide color gamut quantum dot films (containing green quantum dots with the core of CdSe and red Quantum dots and having a high cadmium content (about 100 ppm), the quantum fluorescent film 108 of this embodiment can have a lower cadmium content (about 50 ppm), and the display device including it can maintain a higher color gamut.

In one embodiment, the quantum fluorescent film 108 may include green quantum dots, green phosphor and red phosphor. Because green phosphors replace part of the green quantum dots Therefore, compared with other general wide color gamut quantum dot films, the cadmium content can be further reduced to a quarter, about 25ppm. In one embodiment, when the core material of the green quantum dot is InP, the quantum fluorescent film 108 does not contain cadmium, that is, the cadmium content is 0 ppm.

FIG. 3 is a schematic cross-sectional view of a display device according to a second embodiment of the present invention. In FIG. 3 , the same or similar elements as in FIG. 1 will be represented by the same or similar reference symbols and will not be described again.

Referring to FIG. 3 , in the display device 20 of this embodiment, the cross section of the light guide plate 204 is rectangular. The light guide plate 204 has a light incident surface 204a and a light exit surface 204b that are opposite to each other. The light source 106 is disposed adjacent to the back surface (light incident surface 204a) of the light guide plate 204 to optically couple with the light guide plate 204 to form a direct structure. The blue light L emitted by the light source 106 enters the light guide plate 204 from the light incident surface 204a, passes inside the light guide plate 204, and is emitted from the light exit surface 204b to reach the quantum fluorescent film 108. The blue light L reaching the quantum fluorescent film 108 may be partially converted into red light and green light, so that the blue light L, red light and green light may be mixed into white light and transmitted to the display panel 102 .

The effects of the light conversion layer of the present invention will be described below with experimental examples and comparative examples.

Experimental example 1

A quantum fluorescent film containing green quantum dots and red phosphor is disposed in a backlight module, and the backlight module is applied to a display device. Green quantum dots are quantum dots with a CdSe/ZnS core-gradient alloy-shell structure. The red phosphor is nitride red phosphor (CaAlSiN ₃ : Eu ²⁺ ).

The white light emission spectrum (shown in Figure 4), color gamut diagram (shown in Figure 5A) and color gamut (shown in Table 1) of the display device were measured.

Comparative example 1

Take a traditional display device containing yellow phosphor and measure the white light emission spectrum (shown in Figure 4), color gamut diagram (shown in Figure 5B) and color gamut (shown in Table 1) of the display device. The yellow phosphor is YAG phosphor (Y ₃ Al ₅ O ₁₂ : Ce).

As shown in Table 1 and FIGS. 5A and 5B , the display device of Experimental Example 1 has a wider color gamut, and the display device of Comparative Example 1 has a narrower color gamut.

Experimental example 2

Half of the green quantum dots in the quantum fluorescent film of Experimental Example 1 were replaced with green phosphor ((Ba,Sr) ₂ SiO ₄ :Eu ²⁺ ), and the white light emission spectrum of the display device containing it was measured. As shown in Figure 4, although the display device of Experimental Example 2 only uses half the quantum dots of Experimental Example 1 (the cadmium content is halved), it can still achieve a light emission effect similar to Experimental Example 1, while maintaining the advantage of the wide color gamut of the display device. , while reducing the cadmium content by half.

From the above, it can be seen that compared with traditional display devices containing yellow phosphor, The display device of the present invention has a wider color gamut. Therefore, the display device of the present invention can display more colors more accurately. In addition, compared with other display devices using cadmium-containing quantum dot films, the display device of the present invention can maintain the advantage of a wide color gamut while reducing the cadmium content.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some modifications and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

108: Quantum fluorescent film 110: Light conversion layer 110a: Resin material 110b: Quantum dots 110c: fluorescent powder 112: First base material 114: Second base material

Claims (19)

A backlight module includes: a quantum fluorescent film, including: a light conversion layer including a resin material, a plurality of quantum dots and a plurality of phosphors, wherein the plurality of quantum dots and the plurality of phosphors are dispersed in In the resin material, the quantum dots have a core-gradient alloy-shell structure. The backlight module of claim 1, further comprising: a light source emitting blue light; and a light guide plate optically coupled to the light source, wherein the quantum fluorescent film is disposed on the light exit surface of the light guide plate. The backlight module of claim 2, wherein the light source is disposed adjacent to the side of the light guide plate to form an edge-lit structure. The backlight module of claim 2, wherein the light source is disposed adjacent to the back of the light guide plate to form a direct structure. The backlight module of claim 1, wherein the quantum fluorescent film further includes a first substrate and a second substrate, and the light conversion layer is disposed on the first substrate and the second substrate. between materials. The backlight module of claim 5, wherein the first substrate includes a gas barrier layer. The backlight module of claim 5, wherein the first substrate does not include a gas barrier layer. The backlight module of claim 5, wherein the second substrate includes a gas barrier layer. The backlight module of claim 5, wherein the second substrate does not include a gas barrier layer. The backlight module of claim 1 further includes an optical film disposed on the quantum fluorescent film. The backlight module of claim 10, wherein the optical film includes a brightness enhancement film, a diffusion film, a polarizing film or a combination thereof. The backlight module of claim 1, wherein the resin material includes acrylic resin, epoxy resin, silicone or a combination thereof. The backlight module of claim 1, wherein the core material of the quantum dots includes CdSe or InP. The backlight module of claim 1, wherein the material of the quantum dot shell includes ZnSe or ZnS. The backlight module of claim 1, wherein the quantum dots include green quantum dots, red quantum dots or a combination thereof. The backlight module of claim 1, wherein the phosphor includes green phosphor, red phosphor or a combination thereof. The backlight module of claim 16, wherein the green phosphor material includes (Ba,Sr) ₂ SiO ₄ : Eu ²⁺ , Si _6-z Al _z O _z N _8-z : Eu ²⁺ , Al _1.7 O _2.1 N _0.3 : Mn ²⁺ , Eu ²⁺ or their combination. The backlight module of claim 16, wherein the red phosphor material includes CaAlSiN ₃ :Eu ²⁺ , Sr ₂ Si ₅ N ₈ : Eu ²⁺ , K ₂ SiF ₆ : Mn ⁴⁺ or a combination thereof . A display device includes: a display panel; and the backlight module according to any one of claims 1 to 18, which is disposed on one side of the display panel.