TWI847680B - Display panel - Google Patents

Abstract

A display panel including a first substrate, a second substrate, a plurality of pixel structures and a display medium layer is provided. The second substrate overlaps the first substrate. The display medium layer is sandwiched between the first substrate and the second substrate. The pixel structures each include a transparent conductive layer, a reflective metal layer and at least one optical auxiliary layer. The transparent conductive layer is disposed on the first substrate. The reflective metal layer is disposed between the first substrate and the transparent conductive layer, and overlaps the transparent conductive layer. The at least one optical auxiliary layer overlap the transparent conductive layer and the reflective metal layer, and contact at least one of the transparent conductive layer and the reflective metal layer. The refractive index of the at least one optical auxiliary layer is greater than 1.85 or less than 1.65.

Description

Display Panel

The present invention relates to a display technology, and in particular to a display panel.

General liquid crystal display panels can be divided into three categories: transmissive, reflective, and semi-transmissive. The classification is based on the difference in the light source used. Among them, reflective LCD panels mainly use natural light, ambient light, or front light as the lighting source. Therefore, it has the advantages of low power consumption and high outdoor visibility, and its application in readers and commercial displays (such as billboards, electronic labels, sports watches, etc.) is expanding year by year. In the current reflective display panels, in order to effectively utilize ambient light, the reflective layer is mostly made of metal with high reflectivity (such as silver or aluminum), and the reflective metal is coated with a transparent conductive layer to prevent the reflective metal from oxidizing and causing a decrease in reflectivity.

Although silver metal has excellent reflectivity in the visible and infrared bands, its reflectivity in short-wave bands (such as the blue band or the ultraviolet band) is relatively poor. Therefore, it is easy for the b* of the reflected light in the CIELAB color space to be large, causing the problem of color cast. A method of reducing the thickness of the transparent conductive layer disposed on the light-incident side of the reflective metal layer to increase the reflectivity has been proposed. However, an overly thin transparent conductive layer will lose its protective effect on the reflective metal layer, making the reflective metal easily affected by external substances and discolored, causing the color cast of the reflected light.

The present invention provides a display panel having high reflectivity and good color rendering of white screen.

The display panel of the present invention includes a first substrate, a second substrate, a plurality of pixel structures and a display medium layer. The second substrate is overlapped with the first substrate, and the display medium layer is sandwiched between the first substrate and the second substrate. The plurality of pixel structures each include a transparent conductive layer, a reflective metal layer and at least one optical auxiliary layer. The transparent conductive layer is disposed on the first substrate. The reflective metal layer is disposed between the first substrate and the transparent conductive layer and overlaps the transparent conductive layer. At least one optical auxiliary layer overlaps the transparent conductive layer and the reflective metal layer and contacts at least one of the transparent conductive layer and the reflective metal layer. The refractive index of at least one optical auxiliary layer is greater than 1.85 or less than 1.65.

In an embodiment of the present invention, each of the plurality of pixel structures of the display panel further includes another transparent conductive layer disposed between the first substrate and the reflective metal layer. The other transparent conductive layer overlaps the reflective metal layer and contacts the reflective metal layer.

In an embodiment of the present invention, the transparent conductive layer of the display panel is located between at least one optical auxiliary layer and the reflective metal layer, and contacts at least one optical auxiliary layer and the reflective metal layer.

In an embodiment of the present invention, each of the plurality of pixel structures of the display panel further includes an active element, and the transparent conductive layer and the reflective metal layer are electrically connected to the active element.

In one embodiment of the present invention, each of the plurality of pixel structures of the display panel further includes an active element and a pixel electrode. The pixel electrode is electrically connected to the active element and overlaps the transparent conductive layer. At least one optical auxiliary layer is sandwiched between the pixel electrode and the transparent conductive layer, and the pixel electrode is electrically independent of the transparent conductive layer and the reflective metal layer.

In one embodiment of the present invention, the transparent conductive layer and the reflective metal layer of the display panel are capacitively coupled to the pixel electrode.

In an embodiment of the present invention, the refractive index of the transparent conductive layer of the display panel is greater than 1.85, and at least one optical auxiliary layer is an optical auxiliary layer with a refractive index less than 1.65.

In one embodiment of the present invention, at least one optical auxiliary layer of the display panel comprises a plurality of first optical auxiliary layers and a plurality of second optical auxiliary layers stacked alternately, wherein the refractive index of each of the first optical auxiliary layers is greater than 1.85, and the refractive index of each of the second optical auxiliary layers is less than 1.65.

In one embodiment of the present invention, the at least one optical auxiliary layer of the display panel includes at least one auxiliary metal layer. The at least one auxiliary metal layer is disposed between the reflective metal layer and the transparent conductive layer and electrically contacts the reflective metal layer and the transparent conductive layer. The refractive index of each of the at least one auxiliary metal layer and the reflective metal layer is less than the refractive index of the transparent conductive layer.

In one embodiment of the present invention, the thickness of at least one auxiliary metal layer and the reflective metal layer of the display panel is less than 150 nanometers.

In an embodiment of the present invention, the at least one auxiliary metal layer of the display panel includes a first auxiliary metal layer, the first auxiliary metal layer contacts the reflective metal layer, and the refractive index of the first auxiliary metal layer is different from the refractive index of the reflective metal layer.

In one embodiment of the present invention, the at least one auxiliary metal layer of the display panel further includes a second auxiliary metal layer. The second auxiliary metal layer is disposed on and contacts the first auxiliary metal layer. The refractive index of the second auxiliary metal layer and the reflective metal layer is greater than or less than the refractive index of the first auxiliary metal layer.

In an embodiment of the present invention, the thickness of the reflective metal layer of the display panel is greater than the thickness of the first auxiliary metal layer, and the thickness of the first auxiliary metal layer is greater than the thickness of the second auxiliary metal layer.

In an embodiment of the present invention, the at least one optical auxiliary layer of the display panel further includes at least one auxiliary insulating layer, and the transparent conductive layer is disposed between the at least one auxiliary metal layer and the at least one auxiliary insulating layer.

In one embodiment of the present invention, each of the plurality of pixel structures of the display panel further includes an active element and a pixel electrode disposed on the second substrate. The pixel electrode is electrically connected to the active element. A common electrode layer is disposed between the display medium layer and the first substrate. The active element and the pixel electrode are disposed between the display medium layer and the second substrate, and a transparent conductive layer, a reflective metal layer and at least one optical auxiliary layer are disposed between the display medium layer and the first substrate.

Based on the above, in a display panel of an embodiment of the present invention, the reflectivity of the reflective metal layer disposed between two transparent conductive layers can be improved by disposing an optical auxiliary layer and allowing the optical auxiliary layer to contact at least one of the reflective metal layer or the transparent conductive layer located on the light incident side, wherein the refractive index of the optical auxiliary layer is greater than 1.85 or less than 1.65. In addition, such a configuration can also increase the color rendering of the display panel.

Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and description to represent the same or similar parts.

Fig. 1 is a schematic cross-sectional view of a display panel according to the first embodiment of the present invention. Fig. 2 is a schematic diagram of incident light and reflected light of the first embodiment of the present invention. Fig. 3 is a graph of reflectivity versus wavelength of the display panel of Fig. 1 with optical auxiliary layers of different film thicknesses. Fig. 4 is a distribution graph of reflectivity of the display panel of Fig. 1 and b* in the CIELAB color space for optical auxiliary layers of different film thicknesses. Fig. 5 is a graph of reflectivity versus wavelength of the display panel of Fig. 1 with different types of optical auxiliary layers. Fig. 6 is a distribution graph of reflectivity of the display panel of Fig. 1 and b* in the CIELAB color space for different types of optical auxiliary layers. Fig. 7 is a schematic cross-sectional view of another modified embodiment of the optical auxiliary layer of Fig. 1.

1 , the display panel 10 includes a first substrate 101, a second substrate 102, a plurality of pixel structures PX, and a display medium layer 150. The first substrate 101 and the second substrate 102 are overlapped. The display medium layer 150 is sandwiched between the first substrate 101 and the second substrate 102. In this embodiment, the display medium layer 150 is, for example, a liquid crystal layer or other materials having light modulation capability.

The pixel structure PX includes an active element T, a first transparent conductive layer TCL1, a second transparent conductive layer TCL2 and a reflective metal layer RML. The first transparent conductive layer TCL1 is disposed on the first substrate 101. The second transparent conductive layer TCL2 is disposed on the first transparent conductive layer TCL1 and overlaps the first transparent conductive layer TCL1. The reflective metal layer RML is disposed between the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 and overlaps the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2. In this embodiment, the reflective metal layer RML can contact the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 at the same time. That is, the reflective metal layer RML is sandwiched between the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2, but the present invention is not limited thereto. In the present embodiment, because the reflective metal layer RML has poor adhesion to the insulating layer 110, the first transparent conductive layer TCL1 is disposed between the reflective metal layer RML and the insulating layer 110 to increase adhesion and prevent the reflective metal layer RML from peeling off. In addition, in order to protect the reflective metal layer RML and prevent the reflective metal layer RML from chemically reacting with external substances to cause the reflective metal layer RML to change color, thereby causing a decrease in reflectivity and a change in b* value, the present invention disposes the second transparent conductive layer TCL2 on the reflective metal layer RML to protect the reflective metal layer RML.

For example, in this embodiment, the side of the second substrate 102 of the display panel 10 that is opposite to the display medium layer 150 can be the light incident side of the ambient light EB or the front light FB. The display panel 10 may further include a plurality of data lines (not shown) and a plurality of scan lines (not shown), wherein each active element T can be electrically connected to a data line and a scan line. The active element T is, for example, a thin film transistor or other switching element with three terminals. That is, the pixel array substrate of the display panel 10 of this embodiment includes a first substrate 101 and a plurality of pixel structures PX disposed on the first substrate 101.

In the present embodiment, the first transparent conductive layer TCL1, the second transparent conductive layer TCL2 and the reflective metal layer RML disposed on the first substrate 101 are electrically connected to each other and can constitute a reflective electrode RE of the pixel structure PX, and are electrically connected to a corresponding active element T, but not limited thereto. For example, the gate, source and drain (not shown) of the active element T can be electrically connected to a scanning line (not shown), a data line (not shown) and the reflective electrode RE, respectively. In the present embodiment, the display panel 10 can be a reflective type panel or a transflective type panel, and the reflective electrode RE is disposed in the reflective area of the display panel 10, and is used to reflect the ambient light EB or the front light FB to form a reflected light RB to display the corresponding picture. FIG1 shows that the reflective electrode RE is electrically connected to the reflective electrode RE through the through hole TH of the insulating layer 110, but the present invention is not limited thereto. In some embodiments, the display panel 10 may further include at least one connecting electrode, which is located between the active element T and the reflective electrode RE, and the reflective electrode RE is electrically connected to the active element T through the at least one connecting electrode. In this embodiment, the material of the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 is, for example, a metal oxide, which may include indium tin oxide, indium zinc oxide, aluminum tin oxide, aluminum zinc oxide, or other suitable oxides, or a stacked layer of at least two of the above. The material of the reflective metal layer RML may include silver, aluminum, or other metal materials with high reflectivity.

It is particularly noted that the film thickness t1 of the second transparent conductive layer TCL2 closer to the light incident side can be smaller than the film thickness t2 of the first transparent conductive layer TCL1 farther from the light incident side, so as to improve the reflectivity of the reflective electrode RE and the b* value in the CIELAB color space. In the experiment of the present invention, when the film thickness t1 of the second transparent conductive layer TCL2 is reduced from 80 angstroms to 50 angstroms, the reflectivity is increased by 0.6%, and the b* value can be reduced by 0.5. For example, in this embodiment, the film thickness t1 of the second transparent conductive layer TCL2 is, for example, 50 angstroms, and the film thickness t2 of the first transparent conductive layer TCL1 is, for example, 80 angstroms. That is, the film thicknesses of the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 are both less than 10 nanometers. Here, the film thickness of the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 is, for example, the film thickness of the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 in a direction perpendicular to the upper surface of the first substrate 101 (i.e., the surface of the first substrate 101 facing the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2) (i.e., direction Z). Unless otherwise specified below, the film thickness of the film layer is defined in the same manner and will not be repeated.

On the other hand, a color filter layer 170 may be disposed on the second substrate 102, but the present invention is not limited thereto. In an embodiment where the display panel 10 is a black and white display panel, the display panel 10 may not have a color filter layer 170. More specifically, the color filter layer 170 is disposed on the second substrate 102 and is located between the display medium layer 150 and the second substrate 102. For example, the color filter layer 170 may have a plurality of color filter patterns (not shown) disposed respectively corresponding to a plurality of pixel structures PX, and these color filter patterns are suitable for allowing light of different colors (e.g., red light, green light, and blue light) to pass through, but the present invention is not limited thereto.

In this embodiment, a common electrode layer 180 may also be provided on the second substrate 102. That is, the color filter substrate of the display panel 10 of this embodiment includes the second substrate 102, the color filter layer 170 and the common electrode layer 180. In this embodiment, the reflective electrode RE is electrically connected to the drain of the corresponding active element T to receive the pixel data provided by the data line, so the reflective electrode RE can also serve as a pixel electrode, and the common electrode layer 180 and the reflective electrode RE on the first substrate 101 are suitable for generating an electric field for driving the display medium layer 150 (such as liquid crystal molecules of the liquid crystal layer), but not limited thereto. The material of the common electrode layer 180 is, for example, a metal oxide, which may include indium tin oxide, indium zinc oxide, aluminum tin oxide, aluminum zinc oxide, or other suitable oxides, or a stacked layer of at least two of the above.

As described above, when the film thickness t1 of the second transparent conductive layer TCL2 is reduced, the reflectivity can be improved and the b* value can be reduced. However, when the film thickness t1 of the second transparent conductive layer TCL2 is too low, the effect of protecting the reflective metal layer RML will be reduced. Therefore, in this embodiment, in order to improve the reflectivity of the ambient light EB and reduce the b* value, and maintain the protective effect on the reflective metal layer RML, the pixel structure PX of the display panel 10 further includes an optical auxiliary layer 130, which is disposed on the second transparent conductive layer TCL2, and the material of the optical auxiliary layer 130 is different from that of the second transparent conductive layer TCL2.

Please refer to FIG. 2 . This embodiment utilizes the principle of optical thin film interference to form an optical auxiliary layer 130 on the reflective electrode RE. The refractive index of the optical auxiliary layer 130 is different from the refractive index of the second transparent conductive layer TCL2. The incident light IL is reflected at the interface between the optical auxiliary layer 130 and the second transparent conductive layer TCL2 and the interface between the second transparent conductive layer TCL2 and the reflective metal layer RML. Therefore, the reflectivity of the ambient light EB or the front light FB and the b* value can be increased by adjusting the film thickness. Specifically, in this embodiment, the stacked structure of the second transparent conductive layer TCL2 and the optical auxiliary layer 130 can be called an optical adjustment film, which is disposed on the reflective metal layer RML and is used to adjust the reflectivity and the b* value. In addition, the stacking structure of the second transparent conductive layer TCL2 and the optical auxiliary layer 130 in this embodiment further enhances the ability to protect the reflective metal layer RML to prevent the reflective metal layer RML from reacting with external substances and causing discoloration. The optical auxiliary layer 130 overlaps the first transparent conductive layer TCL1, the second transparent conductive layer TCL2 and the reflective metal layer RML, and contacts the second transparent conductive layer TCL2. The overlapping relationship here is, for example, along the stacking direction of the first transparent conductive layer TCL1, the second transparent conductive layer TCL2 and the reflective metal layer RML (for example, the direction Z of FIG. 1). If not specifically mentioned below, the overlapping relationship of the two components is defined in the same way and will not be repeated.

In the present embodiment, the optical auxiliary layer 130 may be a low refractive index layer. The low refractive index layer in this article refers to a film layer with a refractive index of, for example, less than 1.65. For example, the optical auxiliary layer 130 may be made of silicon dioxide (SiO ₂ ) with a refractive index of about 1.45, but is not limited thereto. Referring to FIG. 3 , curve C1 shows the variation of the reflectivity of the display panel of the comparative example without the optical auxiliary layer 130 (i.e., the film thickness condition is TK0) to the wavelength, and curves E1 to E4 respectively show that the optical auxiliary layer 130 of the display panel 10 is silicon dioxide and has a film thickness of 500 angstroms (i.e., the film thickness condition is TK1), 1000 angstroms (i.e., the film thickness condition is TK2), 1 The variation of reflectivity with wavelength at 200 angstroms (i.e., film thickness condition is TK3) and 1500 angstroms (i.e., film thickness condition is TK4), wherein the material of the reflective metal layer RML is, for example, silver, and its film thickness is 1500 angstroms, and the material of the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 is, for example, indium tin oxide (ITO), and their film thicknesses are 80 angstroms and 50 angstroms, respectively.

FIG4 shows the reflectivity of the display panel 10 with different film thicknesses of the optical auxiliary layer 130 in FIG3 for light with a wavelength of 550 nanometers and the b* value in the CIELAB color space. It should be noted that FIG4 also shows the reflectivity of the display panel 10 with a wavelength of 550 nanometers and the b* value in the CIELAB color space when the optical auxiliary layer 130 is silicon dioxide and has a film thickness of 800 angstroms (i.e., the film thickness condition is TK5). As can be seen from FIG4, the reflectivity of the display panel 10 with a wavelength of 550 nanometers gradually increases as the film thickness of the optical auxiliary layer 130 increases.

It is particularly noteworthy that, although the reflectivity of the display panel of the comparative example without the optical auxiliary layer 130 (TK0) for light with a wavelength of 550 nanometers is close to the reflectivity of the display panel 10 for light with a wavelength of 550 nanometers when the film thickness of the optical auxiliary layer 130 is 1500 angstroms (TK4), both of them will cause the display panel to produce a larger b* value in the CIELAB color space and produce a more obvious color shift. As shown in FIG. 4 , when the film thickness of the optical auxiliary layer 130 of the display panel 10 is 1200 angstroms (i.e., the film thickness condition is TK3), although its reflectivity for light with a wavelength of 550 nanometers is slightly lower than that of the display panels with the film thickness conditions of the optical auxiliary layer 130 being TK0 and TK4, its b* value in the CIELAB color space is significantly smaller. In other words, the film thickness condition TK3 of the optical auxiliary layer 130 (i.e., the film thickness is 1200 angstroms) may be a better choice for the display panel 10.

However, the present invention is not limited thereto. In another variant embodiment of the display panel 10, the optical auxiliary layer 130 may be a high refractive index layer. The high refractive index layer herein refers to a film layer having a refractive index greater than 1.85, for example. For example, the optical auxiliary layer 130 may be made of titanium dioxide (TiO ₂ ) having a refractive index of about 2.4, but is not limited thereto. Referring to FIG. 5 , curve C1 shows the variation of the reflectivity of the display panel of the comparative example without the optical auxiliary layer 130 (i.e., the film thickness condition is TK0) to the wavelength, curve E3 shows the variation of the reflectivity to the wavelength when the optical auxiliary layer 130 of the display panel 10 is made of SiO ₂ and its film thickness is 1200 angstroms (i.e., the film thickness condition is TK3), and curve E5 shows the variation of the reflectivity of the display panel 10 when the optical auxiliary layer 130 is made of TiO ₂ and the film thickness is 500 angstroms (i.e., the film thickness condition is TK1), wherein the material of the reflective metal layer RML is, for example, silver, and its film thickness is 1500 angstroms, and the materials of the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 are, for example, indium tin oxide (ITO), and their film thicknesses are 80 angstroms and 50 angstroms, respectively.

FIG6 shows the reflectivity of each curve in FIG5 at a wavelength of 550 nanometers. As can be seen from FIG6, compared with the optical auxiliary layer 130 made of _SiO2 , the optical auxiliary layer 130 made of _TiO2 can further improve the reflectivity of the display panel for light with a wavelength of 550 nanometers, and the b* value in the CIELAB color space can also be significantly reduced (for example: b* can be reduced from 3 to 1), thereby improving the image quality of the display panel.

Compared with a display panel without an optical auxiliary layer 130 (i.e., the film thickness condition is TK0), regardless of whether the optical auxiliary layer 130 is made of _SiO2 or _TiO2 (i.e., whether the optical auxiliary layer 130 is made of a low refractive index layer or a high refractive index layer), there is a significant improvement effect (i.e., reducing the b* value) on the b* value in the CIELAB color space. It is particularly noted that the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 made of indium tin oxide have a refractive index of about 1.85, and the optical auxiliary layer 130 (as shown in FIG. 1 ) covering and contacting the second transparent conductive layer TCL2 has a greater difference in refractive index with the second transparent conductive layer TCL2, which has a more obvious effect on the adjustment of the reflectivity and the b* value in the CIELAB color space.

For example, the difference in refractive index between the optical auxiliary layer 130 made of TiO ₂ and the second transparent conductive layer TCL2 made of indium tin oxide is greater than the difference in refractive index between the optical auxiliary layer 130 made of SiO ₂ and the second transparent conductive layer TCL2 made of indium tin oxide. Therefore, when the second transparent conductive layer TCL2 is made of indium tin oxide, the optical auxiliary layer 130 is made of a material having a large difference in refractive index from indium tin oxide (such as TiO ₂ ), which can produce a more obvious improvement effect on the reflectivity and the b* value in the CIELAB color space.

In the above embodiment, the second transparent conductive layer TCL2 is indium tin oxide as an example. On the other hand, in other embodiments, the second transparent conductive layer TCL2 can be made of a material having a refractive index greater than that of indium tin oxide (the refractive index of indium tin oxide is about 1.85), and the optical auxiliary layer 130 is a low refractive index layer (i.e., a film layer having a refractive index less than 1.65) to increase the refractive index difference between the optical auxiliary layer 130 and the second transparent conductive layer TCL2, thereby improving the reflectivity and the b* value in the CIELAB color space. For example, the second transparent conductive layer TCL2 may be indium zinc oxide (IZO), the refractive index of which is approximately 2.3, and the optical auxiliary layer 130 may be SiO ₂ (refractive index is approximately 1.45). Therefore, compared with a stacked structure in which the optical auxiliary layer 130 and the second transparent conductive layer TCL2 are respectively SiO ₂ and indium tin oxide, the stacked structure in which the optical auxiliary layer 130 and the second transparent conductive layer TCL2 are respectively SiO ₂ and indium zinc oxide can increase the refractive index difference between the optical auxiliary layer 130 and the second transparent conductive layer TCL2, and further improve the reflectivity and the b* value in the CIELAB color space.

Please refer to Figure 7, in another variant embodiment of the display panel 10 of Figure 1, the optical auxiliary layer 130" can also be made of two different materials. For example, the optical auxiliary layer 130" may include a plurality of first optical auxiliary layers 131 and a plurality of second optical auxiliary layers 132. These first optical auxiliary layers 131 and these second optical auxiliary layers 132 are alternately stacked along a direction perpendicular to the upper surface of the first substrate 101 (such as direction Z in Figure 1). It is particularly noteworthy that the refractive index of the first optical auxiliary layer 131 may be greater than the refractive index of the second optical auxiliary layer 132, but is not limited to this. For example, the first optical auxiliary layer 131 can be the high refractive index layer mentioned above, and the second optical auxiliary layer 132 can be the low refractive index layer mentioned above, that is, the refractive index of each of the first optical auxiliary layers 131 can be greater than 1.85, and the refractive index of each of the second optical auxiliary layers 132 can be less than 1.65. For example, the first optical auxiliary layer 131 can be made of _TiO2 , and the second optical auxiliary layer 132 can be made of _SiO2 , but it is not limited thereto. In FIG. 7 , three first optical auxiliary layers 131 and two second optical auxiliary layers 132 are alternately stacked to form an optical auxiliary layer 130″ as an example, but the present invention is not limited to this. In the present invention, the optical auxiliary layer 130″ may be a stacked structure of ((first optical auxiliary layer 131/second optical auxiliary layer 132)*number of loops)/first optical auxiliary layer 131, wherein the number of loops is a positive integer greater than or equal to 1. In FIG. 7 , the number of loops is 2, and thus the optical auxiliary layer 130 ″ is formed by the first optical auxiliary layer 131 / the second optical auxiliary layer 132 / the first optical auxiliary layer 131 / the second optical auxiliary layer 132 / the first optical auxiliary layer 131 arranged in sequence along the direction Z. The present invention does not limit the number of loops.

In some embodiments, the display panel 10 may further include two alignment films (not shown), which are respectively disposed on opposite sides of the display medium layer 150, wherein one alignment film is disposed on the optical auxiliary layer 130 or the optical auxiliary layer 130″ (i.e., between the optical auxiliary layer 130 and the display medium layer 150, or between the optical auxiliary layer 130″ and the display medium layer 150), and the other alignment film is disposed between the common electrode layer 180 and the display medium layer 150. For example, the display medium layer 150 may be a liquid crystal layer, and the alignment film may include any material suitable for aligning liquid crystal molecules (such as but not limited to polyimide).

Other embodiments are listed below to illustrate the present disclosure in detail, wherein the same components are marked with the same symbols, and the description of the same technical content is omitted. For the omitted parts, please refer to the aforementioned embodiments, which will not be described in detail below.

FIG8 is a cross-sectional schematic diagram of a display panel according to a second embodiment of the present invention. Referring to FIG8, unlike the display panel 10 of FIG1, the reflective electrode RE' and the active element T' of the display panel 10A of this embodiment are respectively located on the first substrate 101 and the second substrate 102 facing each other and are respectively located on different sides of the display medium layer 150, and the optical auxiliary layer 130' is located on the first substrate 101 and between the reflective electrode RE' and the display medium layer 150. In this embodiment, the color filter layer 170' and the common electrode layer 180' are disposed on the first substrate 101, and the pixel electrode PE' and the active element T' of the pixel structure PX' are disposed on the second substrate 102, and the pixel electrode PE' and the active element T' are electrically connected to each other through the through hole TH' of the insulating layer 110'. That is, the pixel array substrate of the display panel 10A of this embodiment includes the second substrate 102, the active element T' and the pixel electrode PE', and the color filter substrate of the display panel 10A includes the first substrate 101, the common electrode layer 180', the color filter layer 170', the reflective electrode RE' and the optical auxiliary layer 130'.

It is particularly noted that, unlike FIG. 1 in which the first transparent conductive layer TCL1, the second transparent conductive layer TCL2, the reflective metal layer RML and the optical auxiliary layer 130 are disposed on the pixel array substrate, the first transparent conductive layer TCL1', the second transparent conductive layer TCL2', the reflective metal layer RML' and the optical auxiliary layer 130' of this embodiment are disposed on the color filter substrate. Since the pixel electrode PE' is disposed on the second substrate 102, the common electrode layer 180' of this embodiment is correspondingly changed to be disposed on the first substrate 101, so that it and the pixel electrode PE' can generate an electric field for driving the display medium layer 150, but the present invention is not limited thereto.

In this embodiment, the side of the second substrate 102 of the display panel 10A facing away from the display medium layer 150 can be the light incident side of the ambient light EB or the front light FB. The display panel 10A can be a reflective panel or a semi-transmissive and semi-reflective panel. The reflective electrode RE' is arranged in the reflective area of the display panel 10A and is used to reflect the ambient light EB or the front light FB to form reflected light RB to display the corresponding picture.

The first transparent conductive layer TCL1′, the second transparent conductive layer TCL2′, the reflective metal layer RML′ and the optical auxiliary layer 130′ in this embodiment are respectively similar to the first transparent conductive layer TCL1, the second transparent conductive layer TCL2, the reflective metal layer RML and the optical auxiliary layer 130 in the first embodiment. The material and refractive index selection of the second transparent conductive layer TCL2′ and the optical auxiliary layer 130′ to improve the reflectivity of the display panel and the b* value in the CIELAB color space are also similar to the material and refractive index selection of the second transparent conductive layer TCL2 and the optical auxiliary layer 130 in the first embodiment. Therefore, the description of the same technical content is omitted. Please refer to the aforementioned embodiments for the omitted parts, which will not be repeated here. In addition, the optical auxiliary layer 130' in this embodiment can also be replaced by the optical auxiliary layer 130" in another modified embodiment of the first embodiment.

In some embodiments, the display panel 10A may further include two alignment films (not shown), which are respectively disposed on opposite sides of the display medium layer 150, one of which is disposed on the common electrode layer 180' (i.e., between the common electrode layer 180' and the display medium layer 150), and the other alignment film is disposed between the pixel electrode PE' and the display medium layer 150.

FIG9 is a schematic cross-sectional view of a display panel according to the third embodiment of the present invention. FIG10 is a schematic diagram of incident light and reflected light of the third embodiment of the present invention. FIG11 is a distribution diagram of the reflectivity of the display panel of FIG9 and b* in the CIELAB color space for pixel electrodes of different film thicknesses. Referring to FIG9 , the difference between the display panel 20 of this embodiment and the display panel 10 of FIG1 is that the first transparent conductive layer TCL1-A, the second transparent conductive layer TCL2-A and the reflective metal layer RML-A of this embodiment are not electrically connected to the active element T, that is, the reflective electrode RE-A is not electrically connected to the active element T.

More specifically, in the present embodiment, the pixel structure PX-A of the display panel 20 further includes a pixel electrode PE, that is, the reflective electrode RE-A and the pixel electrode PE of the present embodiment are electrically insulated from each other. The pixel electrode PE is disposed on the optical auxiliary layer 130A and overlaps the second transparent conductive layer TCL2-A. That is, the optical auxiliary layer 130A is sandwiched between the pixel electrode PE and the second transparent conductive layer TCL2-A. The pixel electrode PE is electrically connected to the drain of the corresponding active element T to receive the pixel data provided by the data line. For example, the pixel electrode PE can penetrate the insulating layer 110 and be electrically connected to the active element T.

In some embodiments, the display panel 20 may further include two alignment films (not shown), which are respectively disposed on opposite sides of the display medium layer 150, one of which is disposed on the pixel electrode PE (i.e., between the pixel electrode PE and the display medium layer 150), and the other alignment film is disposed between the common electrode layer 180 and the display medium layer 150.

In this embodiment, the pixel electrode PE is electrically independent of the reflective electrode RE-A (i.e., electrically independent of the first transparent conductive layer TCL1-A, the second transparent conductive layer TCL2-A, and the reflective metal layer RML-A). The reflective electrode RE-A may be floating, or the potential of the reflective electrode RE-A may be different from the potential of the pixel electrode PE. In addition, the optical auxiliary layer 130A may also serve as an insulating layer between the pixel electrode PE and the second transparent conductive layer TCL2-A, and the first transparent conductive layer TCL1-A, the second transparent conductive layer TCL2-A, and the reflective metal layer RML-A may overlap the pixel electrode PE and be capacitively coupled with the pixel electrode PE. That is, the reflective electrode RE-A of the present embodiment may form a storage capacitor SC with the pixel electrode PE and the optical auxiliary layer 130A disposed therebetween. For example, the reflective electrode RE-A of the pixel structure PX-A of the present embodiment may have a ground potential or a fixed potential (for example but not limited to a common potential), but is not limited thereto.

In this embodiment, the pixel electrode PE is made of, for example, indium tin oxide (ITO), and the optical auxiliary layer 130A is made of, for example, the high refractive index layer or the low refractive index layer mentioned above. Since the materials and film thickness configurations of the first transparent conductive layer TCL1-A, the second transparent conductive layer TCL2-A and the reflective metal layer RML-A in this embodiment are similar to the first transparent conductive layer TCL1, the second transparent conductive layer TCL2 and the reflective metal layer RML in FIG. 1 , please refer to the relevant paragraphs of the aforementioned embodiment for detailed description, which will not be repeated here.

Referring to FIG. 10 , the present embodiment utilizes the principle of optical thin film interference to form an optical auxiliary layer 130A on the reflective electrode RE-A. In addition, the pixel electrode PE is disposed on the optical auxiliary layer 130A, and the refractive index of the optical auxiliary layer 130A is different from the refractive index of any of the second transparent conductive layer TCL2-A and the pixel electrode PE. The incident light IL is reflected at the interface between the pixel electrode PE and the optical auxiliary layer 130A, the interface between the optical auxiliary layer 130A and the second transparent conductive layer TCL2-A, and the interface between the second transparent conductive layer TCL2-A and the reflective metal layer RML-A. Therefore, the reflectivity of the ambient light EB and the b* value can be improved by adjusting the film thickness. Specifically, in this embodiment, the stacked structure of the second transparent conductive layer TCL2-A, the optical auxiliary layer 130A and the pixel electrode PE can be called an optical adjustment film, which is disposed on the reflective metal layer RML-A and is used to adjust the reflectivity and the b* value.

In particular, the reflectivity of the display panel 20 for light with a wavelength of 550 nm and the b* value in the CIELAB color space can be changed by adjusting the film thickness of the pixel electrode PE. FIG11 shows the distribution of the reflectivity and the b* value for different film thicknesses of the pixel electrode PE. In FIG11 , the material of the reflective metal layer RML-A is, for example, silver, and its film thickness is 1500 angstroms, the material of the first transparent conductive layer TCL1 and the second transparent conductive layer TCL2 is, for example, indium tin oxide (ITO), and its film thickness is 80 angstroms and 50 angstroms respectively, the material of the optical auxiliary layer 130A is, for example, silicon dioxide, and its film thickness is 1000 angstroms, and the material of the pixel electrode PE is, for example, indium tin oxide (ITO), and its film thickness is 50 angstroms, 100 angstroms, 300 angstroms, and 500 angstroms respectively. As can be seen from FIG11 , when the film thickness of the pixel electrode PE is less than or equal to 300 angstroms, the b* value in the CIELAB color space can be significantly improved.

However, the present invention is not limited to this. According to other embodiments not shown, the optical auxiliary layer between the pixel electrode PE and the second transparent conductive layer TCL2-A can also be made of two different materials. For example, the optical auxiliary layer 130A of the present embodiment can be replaced with the optical auxiliary layer 130" of Figure 7. For example, the optical auxiliary layer 130A can be composed of a first optical auxiliary layer 131 with a refractive index greater than 1.85 and a second optical auxiliary layer 132 with a refractive index less than 1.65, which are alternately stacked, but not limited to this. Accordingly, the reflectivity of the display panel and the adjustment flexibility of the b* value in the CIELAB color space can be further increased.

FIG. 12 is a schematic cross-sectional view of a display panel according to a fourth embodiment of the present invention. Referring to FIG. 12 , unlike the display panel 10 of FIG. 1 , the reflective electrode RE-B and the active element T″ of the display panel 30 of the present embodiment are respectively located on the first substrate 101 and the second substrate 102 facing each other and are respectively located on different sides of the display medium layer 150, and the optical auxiliary layer 130B is located on the first substrate 101 and between the reflective electrode RE-B and the display medium layer 150. In the present embodiment, the color filter layer 170A and the common electrode layer 180A are disposed on the first substrate 101, and the pixel electrode PE″ of the pixel structure PX-B and the active element T″ are disposed on the second substrate 102 and are connected to each other through the through hole TH-A of the insulating layer 110A. That is, the pixel array substrate of the display panel 30 of the present embodiment includes a second substrate 102, an active element T″ and a pixel electrode PE″, and the color filter substrate of the display panel 30 includes a first substrate 101, a common electrode layer 180A, a color filter layer 170A, a reflective electrode RE-B and an optical auxiliary layer 130B. In some embodiments, the display panel 30 may further include two alignment films (not shown), which are respectively disposed on opposite sides of the display medium layer 150, one of which is disposed on the common electrode layer 180A (i.e., between the common electrode layer 180A and the display medium layer 150), and the other alignment film is disposed between the pixel electrode PE″ and the display medium layer 150.

It is particularly noted that in this embodiment, the first transparent conductive layer TCL1-B, the second transparent conductive layer TCL2-B, the reflective metal layer RML-B and the optical auxiliary layer 130B are still disposed on the first substrate 101. That is, unlike FIG. 1 where the first transparent conductive layer TCL1, the second transparent conductive layer TCL2, the reflective metal layer RML and the optical auxiliary layer 130 are disposed on the pixel array substrate, the first transparent conductive layer TCL1-B, the second transparent conductive layer TCL2-B, the reflective metal layer RML-B and the optical auxiliary layer 130B in this embodiment are disposed on the color filter substrate. Since the pixel electrode PE″ is relocated on the second substrate 102, based on a driving method similar to the display medium layer 150 of FIG. 1, the common electrode layer 180A of this embodiment is correspondingly relocated on the first substrate 101 so that it and the pixel electrode PE″ can generate a vertical electric field for driving the display medium layer 150, but not limited to this.

In this embodiment, the display panel 30 may further optionally include a transparent conductive layer 190, which is disposed between the color filter layer 170A and the optical auxiliary layer 130B and contacts the optical auxiliary layer 130B. For example, the transparent conductive layer 190 may be used as a part of the pixel structure PX-B, or as a driving electrode of other functional modules (such as anti-penetration), or used to adjust the reflectivity of the display panel 30 and the b* value in the CIELAB color space, and the present invention is not limited thereto.

Similar to the third embodiment, by sequentially stacking the second transparent conductive layer TCL2-B, the optical auxiliary layer 130B and the transparent conductive layer 190 on the reflective metal layer RML-B, the reflectivity of the display panel 30 and the flexibility of adjusting the b* value in the CIELAB color space can be increased. For example, in this embodiment, the optical auxiliary layer 130B can be made of the high refractive index layer (e.g., titanium dioxide with a refractive index of about 2.4) or the low refractive index layer (e.g., SiO ₂ with a refractive index of about 1.45) described above, and the first transparent conductive layer TCL1-B, the second transparent conductive layer TCL2-B and the transparent conductive layer 190 can be made of indium tin oxide (e.g., with a refractive index of about 1.85), but the present invention is not limited thereto.

However, the present invention is not limited thereto. In another variant embodiment, the second transparent conductive layer TCL2-B and the transparent conductive layer 190 may also be made of a material having a refractive index greater than that of indium tin oxide (e.g., indium zinc oxide having a refractive index of about 2.3). Since the refractive index of the second transparent conductive layer TCL2-B and the transparent conductive layer 190 in the variant embodiment is more different from the refractive index of the optical auxiliary layer 130B (e.g., 1.45 of SiO ₂ ), the thin film interference effect on the incident light is better. Therefore, in addition to increasing the reflectivity of the display panel 30 and the flexibility of adjusting the b* value in the CIELAB color space, the optical film structure can also be further simplified.

However, the present invention is not limited to this. According to other embodiments not shown, the optical auxiliary layer 130B of this embodiment can also be made of two different materials. For example, the optical auxiliary layer 130B of this embodiment can be replaced by the optical auxiliary layer 130" of Figure 7. For example, the optical auxiliary layer 130B can be composed of a first optical auxiliary layer 131 with a refractive index greater than 1.85 and a second optical auxiliary layer 132 with a refractive index less than 1.65, which are alternately stacked, but not limited to this. Accordingly, the reflectivity of the display panel and the adjustment flexibility of the b* value in the CIELAB color space can be further increased.

FIG13 is a schematic cross-sectional view of a display panel according to a fifth embodiment of the present invention. FIG14 is a distribution diagram of the reflectivity of the display panel of FIG13 and b* in the CIELAB color space for auxiliary metal layers of different film thicknesses. Referring to FIG13 , the difference between the display panel 40 of this embodiment and the display panel 10 of FIG1 is that the optical auxiliary layer is disposed at a different position. Specifically, the optical auxiliary layer 130C of the display panel 40 includes an auxiliary metal layer AML. The auxiliary metal layer AML is disposed between the reflective metal layer RML and the second transparent conductive layer TCL2, and contacts the reflective metal layer RML and the second transparent conductive layer TCL2. In this embodiment, the first transparent conductive layer TCL1, the second transparent conductive layer TCL2, the reflective metal layer RML and the auxiliary metal layer AML are electrically connected to each other and can constitute a reflective electrode RE-C of the pixel structure PX-C, and the reflective electrode RE-C is electrically connected to a corresponding active element T, so the reflective electrode RE-C can also serve as a pixel electrode.

It is particularly noted that the refractive indexes of the auxiliary metal layer AML and the reflective metal layer RML are different from each other, and each refractive index is less than the refractive index of the second transparent conductive layer TCL2. Preferably, the refractive index of the auxiliary metal layer AML and the reflective metal layer RML is less than 1.65. For example, in this embodiment, the reflective metal layer RML can be made of aluminum metal (refractive index is, for example, about 1.3), the auxiliary metal layer AML can be made of silver metal (refractive index is, for example, about 0.13), and the second transparent conductive layer TCL2 can be made of indium tin oxide (refractive index is, for example, about 1.85). On the other hand, the film thickness t3 of the reflective metal layer RML and the film thickness t4 of the auxiliary metal layer AML are preferably less than 150 nm.

By providing the auxiliary metal layer AML, the reflectivity of the display panel 40 and the flexibility of adjusting the b* value in the CIELAB color space can be increased. Specifically, in this embodiment, the stacked structure of the optical auxiliary layer 130C and the second transparent conductive layer TCL2 can be called an optical adjustment film, which is provided on the reflective metal layer RML and is used to adjust the reflectivity and the b* value. FIG. 14 shows the reflective metal layer RML made of silver metal and having a film thickness t3 of 1500 angstroms, and having no auxiliary metal layer (i.e., the film thickness of the auxiliary metal layer AML is 0 nanometers) (labeled as condition EA), the reflective metal layer RML made of aluminum metal and having a film thickness t3 of 500 angstroms, and the auxiliary metal layer AML made of silver metal and having a film thickness t4 of 250 angstroms (labeled as condition EB), and the reflective metal layer RML made of aluminum metal and having a film thickness t3 of 500 angstroms. When L is made of aluminum metal and has a film thickness t3 of 500 angstroms, and the auxiliary metal layer AML is made of silver metal and has a film thickness t4 of 500 angstroms (marked as condition EC), the display panel 40 has a reflectivity of light with a wavelength of 550 nanometers and a b* value distribution in the CIELAB color space, wherein the film thickness of the first transparent conductive layer TCL1 is 80 angstroms, and the film thickness of the second transparent conductive layer TCL2 is 50 angstroms.

As shown in FIG. 14 , when the reflective metal layer RML is made of aluminum metal and the film thickness t3 is 500 angstroms, and the auxiliary metal layer AML is made of silver metal and the film thickness t4 is 250 angstroms (i.e., condition EB), the b* value of the display panel 40 in the CIELAB color space is significantly lower than that of condition EA, and at the same time, the film thickness of the silver metal of the display panel can be greatly reduced (from 1500 angstroms of condition EA to 250 angstroms of condition EB), so the cost can be greatly reduced. In addition, the reduction in the b* value of condition EB compared to the b* value of condition EA is significantly greater than the reduction in the b* value of condition EC compared to the b* value of condition EA. That is, when the film thickness t4 of the auxiliary metal layer AML is reduced, the color rendering performance of the display panel 40 is significantly improved.

Although the provision of the auxiliary metal layer AML does not significantly adjust the reflectivity of the display panel 40 , it can indeed significantly change the b* value of the display panel 40 in the CIELAB color space, which helps to improve the color rendering of the display panel 40 .

FIG15 is a schematic cross-sectional view of a display panel according to a sixth embodiment of the present invention. Referring to FIG15 , the difference between the display panel 40′ of this embodiment and the display panel 40 of FIG13 is that the optical auxiliary layer 130C′ of this embodiment includes an auxiliary insulating layer INS in addition to the auxiliary metal layer AML. The auxiliary insulating layer INS is disposed on the second transparent conductive layer TCL2 and contacts the second transparent conductive layer TCL2. The second transparent conductive layer TCL2 and the auxiliary insulating layer INS in this embodiment are respectively similar to the second transparent conductive layer TCL2 and the optical auxiliary layer 130 in the first embodiment, or respectively similar to the second transparent conductive layer TCL2 and the optical auxiliary layer 130' in another modified embodiment of the first embodiment. The materials and refractive indexes of the second transparent conductive layer TCL2 and the auxiliary insulating layer INS are selected to improve the reflectivity of the display panel 40' and the b* value in the CIELAB color space. The materials and refractive indexes of the second transparent conductive layer TCL2 and the optical auxiliary layer 130 in the first embodiment are also selected, or respectively similar to the second transparent conductive layer TCL2 and the optical auxiliary layer 130' in another modified embodiment of the first embodiment. For example, the auxiliary insulating layer INS in the optical auxiliary layer 130C' can be a single-layer film structure with a refractive index greater than 1.85 or less than 1.65, or a multi-layer film structure formed by alternately stacking a film layer with a refractive index greater than 1.85 and a film layer with a refractive index less than 1.65. Specifically, the auxiliary insulating layer INS in the optical auxiliary layer 130C’ in this embodiment is the same as the optical auxiliary layer 130 in the first embodiment or the optical auxiliary layer 130” in another variant embodiment of the first embodiment. In this embodiment, the stacked structure of the auxiliary insulating layer INS in the optical auxiliary layer 130C’, the second transparent conductive layer TCL2 and the auxiliary metal layer AML in the optical auxiliary layer 130C’ can be called an optical adjustment film, which is arranged on the reflective metal layer RML and is used to adjust the reflectivity and b* value.

In some embodiments, the display panel 40' may further include two alignment films (not shown), which are respectively disposed on opposite sides of the display medium layer 150, one of which is disposed on the auxiliary insulating layer INS (i.e., between the auxiliary insulating layer INS and the display medium layer 150), and the other alignment film is disposed between the common electrode layer 180 and the display medium layer 150.

FIG16 is a schematic cross-sectional view of a display panel according to the seventh embodiment of the present invention. FIG17 is a schematic cross-sectional view of another modified embodiment of the optical auxiliary layer of FIG16. Referring to FIG16, the difference between the display panel 40A of this embodiment and the display panel 40 of FIG13 is that the number of auxiliary metal layers is different, and the film thickness relationship between each metal layer is also different. Specifically, in the pixel structure PX-D of this embodiment, the optical auxiliary layer 130D disposed between the second transparent conductive layer TCL2 and the reflective metal layer RML may include a first auxiliary metal layer AML-1 and a second auxiliary metal layer AML-2. The first auxiliary metal layer AML-1 contacts the reflective metal layer RML. The second auxiliary metal layer AML-2 is disposed between the first auxiliary metal layer AML-1 and the second transparent conductive layer TCL2, and contacts the first auxiliary metal layer AML-1 and the second transparent conductive layer TCL2. In this embodiment, the first transparent conductive layer TCL1, the second transparent conductive layer TCL2, the reflective metal layer RML, the first auxiliary metal layer AML-1 and the second auxiliary metal layer AML-2 are electrically connected to each other and can constitute a reflective electrode RE-D of the pixel structure PX-D, and the reflective electrode RE-D is electrically connected to a corresponding active element T, so the reflective electrode RE-D can also serve as a pixel electrode. In this embodiment, the stacked structure of the optical auxiliary layer 130D and the second transparent conductive layer TCL2 can be referred to as an optical adjustment film, which is disposed on the reflective metal layer RML and is used to adjust the reflectivity and the b* value.

It is particularly noted that, in this embodiment, the refractive index of each of the second auxiliary metal layer AML-2 and the reflective metal layer RML is greater than or less than the refractive index of the first auxiliary metal layer AML-1. For example, in an embodiment in which the refractive index of each of the second auxiliary metal layer AML-2 and the reflective metal layer RML is greater than the refractive index of the first auxiliary metal layer AML-1, the second auxiliary metal layer AML-2 and the reflective metal layer RML can be made of aluminum metal (refractive index, for example, about 1.3), and the first auxiliary metal layer AML-1 can be made of silver metal (refractive index, for example, about 0.13), but the present invention is not limited thereto. In some embodiments, the second auxiliary metal layer AML-2 and the reflective metal layer RML may include different materials, and the refractive index of each of the second auxiliary metal layer AML-2 and the reflective metal layer RML is greater than the refractive index of the first auxiliary metal layer AML-1. Since the reflective metal layer RML, the first auxiliary metal layer AML-1, and the second auxiliary metal layer AML-2 are sequentially stacked on the first transparent conductive layer TCL1, a metal thin film interference structure with a refractive index distribution of high-low-high (i.e., a metal thin film interference structure with high refractive index and low refractive index alternated in sequence) can be formed, which helps to increase the adjustment flexibility of b* of the display panel 40A in the CIELAB color space.

However, the present invention is not limited thereto. In another variant embodiment (i.e., an embodiment in which the refractive index of each of the second auxiliary metal layer AML-2 and the reflective metal layer RML is less than the refractive index of the first auxiliary metal layer AML-1), the second auxiliary metal layer AML-2 and the reflective metal layer RML may be made of silver metal (refractive index, for example, about 0.13), and the first auxiliary metal layer AML-1 may be made of aluminum metal (refractive index, for example, about 1.3), but the present invention is not limited thereto. In some embodiments, the second auxiliary metal layer AML-2 and the reflective metal layer RML may include different materials, and the refractive index of each of the second auxiliary metal layer AML-2 and the reflective metal layer RML is less than the refractive index of the first auxiliary metal layer AML-1. Since the reflective metal layer RML, the first auxiliary metal layer AML-1 and the second auxiliary metal layer AML-2 are stacked sequentially on the first transparent conductive layer TCL1, a metal thin film interference structure with a refractive index distribution of low-high-low is formed (that is, a metal thin film interference structure with low refractive index and high refractive index alternating in sequence), but not limited to this.

On the other hand, in this embodiment, the film thickness t3 of the reflective metal layer RML may be greater than the film thickness t4' of the first auxiliary metal layer AML-1, and the film thickness t4' of the first auxiliary metal layer AML-1 may be greater than the film thickness t5 of the second auxiliary metal layer AML-2. In other words, the film thickness of each metal layer stacked on the first transparent conductive layer TCL1 gradually decreases as it moves away from the first transparent conductive layer TCL1 (i.e., direction Z). Accordingly, the adjustment flexibility of b* of the display panel 40A in the CIELAB color space can be further increased, which helps to improve the color rendering of the display panel 40A.

In some embodiments, the optical auxiliary layer 130D may include an auxiliary insulating layer in addition to the first auxiliary metal layer AML-1 and the second auxiliary metal layer AML-2, and may be disposed on the second transparent conductive layer TCL2. The auxiliary insulating layer is similar to the auxiliary insulating layer INS of the optical auxiliary layer 130C' of the sixth embodiment, so the description of the same technical content is omitted, and the omitted part is referred to the aforementioned embodiment, which will not be repeated here.

In another variant embodiment, the optical auxiliary layer may also include a plurality of auxiliary metal layers greater than 2. As shown in FIG17 , the optical auxiliary layer includes first to Mth auxiliary metal layers AML-1 to AML-M, where M is a positive integer greater than 2. The refractive index of each of the reflective metal layer RML and the first to Mth auxiliary metal layers AML-1 to AML-M is less than the refractive index of the second transparent conductive layer TCL2, and the refractive index of each of the reflective metal layer RML and the first to Mth auxiliary metal layers AML-1 to AML-M is preferably less than 1.65. The reflective metal layer RML and the first to Mth auxiliary metal layers AML-1 to AML-M form a metal thin film interference structure with a refractive index distribution of high refractive index and low refractive index alternating in sequence along the direction away from the first transparent conductive layer TCL1 (i.e., direction Z), or form a metal thin film interference structure with a refractive index distribution of low refractive index and high refractive index alternating in sequence. The reflective metal layer RML and the first to Mth auxiliary metal layers AML-1 to AML-M each have a film thickness of less than 150 nanometers. The film thickness of the first auxiliary metal layer AML-1 is smaller than the film thickness of the reflective metal layer RML, and the film thicknesses of the first to Mth auxiliary metal layers AML-1 to AML-M decrease gradually in the direction away from the reflective metal layer RML (i.e., decrease in sequence along the direction Z). That is, in the optical auxiliary layer of the modified embodiment, in addition to the alternating change of the refractive index of the first to Mth auxiliary metal layers AML-1 to AML-M, the film thicknesses of the first to Mth auxiliary metal layers AML-1 to AML-M also decrease toward the light incident side of the display panel.

In summary, the optical auxiliary layer of the display panel includes at least one auxiliary metal layer. The at least one auxiliary metal layer is disposed between the reflective metal layer RML and the second transparent conductive layer TCL2. The reflective metal layer RML and the at least one auxiliary metal layer form a metal thin film interference structure in which the refractive index distribution is a high refractive index and a low refractive index alternating in sequence, or form a metal thin film interference structure in which the refractive index distribution is a low refractive index and a high refractive index alternating in sequence. The refractive index of the reflective metal layer RML and each auxiliary metal layer of the at least one auxiliary metal layer is less than the refractive index of the second transparent conductive layer TCL2, and the refractive index of the reflective metal layer RML and each auxiliary metal layer of the at least one auxiliary metal layer is preferably less than 1.65. The thickness of the reflective metal layer RML and each auxiliary metal layer of the at least one auxiliary metal layer is less than 150 nanometers. The thickness of each auxiliary metal layer of the at least one auxiliary metal layer is less than the thickness of the reflective metal layer RML, and the thickness of each auxiliary metal layer of the at least one auxiliary metal layer gradually decreases in a direction away from the reflective metal layer RML.

In addition, in some embodiments, the optical auxiliary layer may include an auxiliary insulating layer in addition to at least one auxiliary metal layer, and may be disposed on the second transparent conductive layer TCL2. The auxiliary insulating layer may be a single-layer film structure with a refractive index greater than 1.85 or less than 1.65, or a multi-layer film structure formed by alternately stacking a film layer with a refractive index greater than 1.85 and a film layer with a refractive index less than 1.65.

In the embodiment where the optical auxiliary layer includes a single auxiliary metal layer structure (such as the embodiments of FIG. 13 and FIG. 15 ), the lower surface and the upper surface of the auxiliary metal layer contact the reflective metal layer RML and the second transparent conductive layer TCL2 respectively.

In an embodiment where the optical auxiliary layer includes a multi-layer auxiliary metal layer structure (e.g., the embodiment of FIG. 16 and FIG. 17 ), the optical auxiliary layer includes N auxiliary metal layers, where N is a positive integer greater than or equal to 2. The N auxiliary metal layers include first to Nth auxiliary metal layers stacked in sequence along a direction away from the reflective metal layer RML, a lower surface of the first auxiliary metal layer contacts the reflective metal layer RML, and an upper surface of the Nth auxiliary metal layer contacts the second transparent conductive layer TCL2. The refractive index of the reflective metal layer RML and the first to Nth auxiliary metal layers is less than the refractive index of the second transparent conductive layer TCL2, and the refractive index of the reflective metal layer RML and the first to Nth auxiliary metal layers is preferably less than 1.65. The reflective metal layer RML and the first to Nth auxiliary metal layers form a metal thin film interference structure with a refractive index distribution of high refractive index and low refractive index alternating in sequence along a direction away from the reflective metal layer RML, or form a metal thin film interference structure with a refractive index distribution of low refractive index and high refractive index alternating in sequence. The thickness of each of the reflective metal layer RML and the first to Nth auxiliary metal layers is less than 150 nanometers. The thickness of the first auxiliary metal layer is smaller than the thickness of the reflective metal layer RML, and the thicknesses of the first to Nth auxiliary metal layers decrease in sequence along a direction away from the reflective metal layer RML.

FIG. 18 is a schematic cross-sectional view of a display panel according to an eighth embodiment of the present invention. Referring to FIG. 18 , unlike the display panel 40A of FIG. 16 , the reflective electrode RE-E and the active element T″ of the display panel 50 of the present embodiment are respectively located on the first substrate 101 and the second substrate 102 facing each other and are respectively located on different sides of the display medium layer 150, and the optical auxiliary layer 130E is located on the first substrate 101 and between the reflective metal layer RML-B and the display medium layer 150. The color filter layer 170A and the common electrode layer 180A are disposed on the first substrate 101, and the pixel electrode PE″ and the active element T″ of the pixel structure PX-E are disposed on the second substrate 102 and are electrically connected to each other. In other words, the pixel array of the display panel 50 of the present embodiment The substrate includes a second substrate 102, an active element T″ and a pixel electrode PE″, and the color filter substrate of the display panel 50 includes a first substrate 101, a common electrode layer 180A, a first transparent conductive layer TCL1-B, a second transparent conductive layer TCL2-B, a reflective metal layer RML-B, an optical auxiliary layer 130E and a color filter layer 170A. In some embodiments, the display panel 50 may further include two alignment films (not shown), which are respectively disposed on opposite sides of the display medium layer 150, one of which is disposed on the common electrode layer 180A (i.e., between the common electrode layer 180A and the display medium layer 150), and the other alignment film is disposed between the pixel electrode PE″ and the display medium layer 150.

It is particularly noted that in the present embodiment, the first transparent conductive layer TCL1-B, the second transparent conductive layer TCL2-B, the reflective metal layer RML-B, and the first auxiliary metal layer AML-1″ and the second auxiliary metal layer AML-2″ of the optical auxiliary layer 130E are still disposed on the first substrate 101. That is, unlike the first transparent conductive layer TCL1, the second transparent conductive layer TCL2, the reflective metal layer RML and the optical auxiliary layer 130D in FIG. 16 , which are disposed on the pixel array substrate, the first transparent conductive layer TCL1-B, the second transparent conductive layer TCL2-B, the reflective metal layer RML-B and the optical auxiliary layer 130E in the present embodiment are disposed on the color filter substrate. Since the pixel electrode PE″ is relocated on the second substrate 102, based on a driving method similar to the display medium layer 150 of FIG. 1, the common electrode layer 180A of this embodiment is correspondingly relocated on the first substrate 101 so that it and the pixel electrode PE″ can generate a vertical electric field for driving the display medium layer 150, but not limited to this.

In this embodiment, the optical auxiliary layer 130E may further include an auxiliary insulating layer INS-A disposed on the second transparent conductive layer TCL2-B, wherein the second transparent conductive layer TCL2-B is disposed between the second auxiliary metal layer AML-2″ and the auxiliary insulating layer INS-A.

By sequentially stacking the first auxiliary metal layer AML-1", the second auxiliary metal layer AML-2", the second transparent conductive layer TCL2-B and the auxiliary insulating layer INS-A on the reflective metal layer RML-B, the reflectivity of the display panel 50 and the adjustment flexibility of the b* value in the CIELAB color space can be increased.

For example, in this embodiment, the auxiliary insulating layer INS-A can be made of a material with a refractive index less than 1.65 (e.g., SiO ₂ with a refractive index of about 1.45), and the second transparent conductive layer TCL2-B can be made of indium tin oxide with a refractive index of about 1.85. However, the present invention is not limited thereto. In another variant embodiment not shown, the second transparent conductive layer TCL2-B can also be made of a material with a refractive index greater than 1.85 (e.g., indium zinc oxide with a refractive index of about 2.3). Since the refractive index of the second transparent conductive layer TCL2-B in the variant embodiment is more different from the refractive index of the auxiliary insulating layer INS-A (e.g., 1.45 of SiO ₂ ), its thin film interference effect on incident light will be better. Therefore, in addition to increasing the reflectivity of the display panel 50 and the flexibility of adjusting the b* value in the CIELAB color space, the optical film structure can also be further simplified.

In another variant embodiment not shown, the auxiliary insulating layer of the optical auxiliary layer can also be made of two different materials, for example, a first auxiliary insulating layer with a refractive index greater than 1.85 and a second auxiliary insulating layer with a refractive index less than 1.65 are alternately stacked, but not limited to this.

Since the material selection and refractive index configuration relationship of the first auxiliary metal layer AML-1", the second auxiliary metal layer AML-2" and the reflective metal layer RML-B in this embodiment are similar to the first auxiliary metal layer AML-1, the second auxiliary metal layer AML-2 and the reflective metal layer RML in Figure 16, please refer to the relevant paragraphs of the aforementioned embodiments for detailed description, which will not be repeated here.

Furthermore, in this embodiment, the film thickness t3" of the reflective metal layer RML-B, the film thickness t4" of the first auxiliary metal layer AML-1" and the film thickness t5" of the second auxiliary metal layer AML-2" can also be configured in a gradual manner as the film thickness of each metal layer in Figure 16.

In summary, in a display panel of an embodiment of the present invention, the reflectivity of the reflective metal layer disposed between two transparent conductive layers can be improved by disposing an optical auxiliary layer and allowing the optical auxiliary layer to contact at least one of the reflective metal layer and the transparent conductive layer located on the light incident side, wherein the refractive index of the optical auxiliary layer is greater than 1.85 or less than 1.65. In addition, such a configuration can also increase the color rendering of the display panel.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technical personnel in this field should understand that they can still modify the technical solutions described in the above embodiments, or replace part or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

10, 10A, 20, 30, 40, 40', 40A, 50: display panel 101: first substrate 102: second substrate 110, 110', 110A: insulating layer 130, 130', 130", 130A, 130B, 130C, 130C', 130D, 130E: optical auxiliary layer 131: first optical auxiliary layer 132: second optical auxiliary layer 150: display medium layer 170, 170', 170A: color filter layer 180, 180', 180A: common electrode layer 190: transparent conductive layer AML, AML-1, AML-2, AML-M, AML-1”, AML-2”: auxiliary metal layer C1, E1, E2, E3, E4, E5: curve EB: ambient light FB: front light INS, INS-A: auxiliary insulating layer IL: incident light PE, PE’, PE”: pixel electrode PX, PX’, PX-A, PX-B, PX-C, PX-D, PX-E: pixel structure RB: reflected light RE, RE’, RE-A, RE-B, RE-C, RE-D, RE-E: reflective electrode SC: storage capacitor RML, RML’, RML-A, RML-B: reflective metal layer T, T’, T”: active element t1, t2, t3, t4, t4’, t5, t3”, t4”, t5”: film thickness TCL1, TCL1’, TCL1-A, TCL1-B: first transparent conductive layer TCL2, TCL2’, TCL2-A, TCL2-B: second transparent conductive layer TH, TH’, TH-A: perforation Z: direction

FIG. 1 is a schematic cross-sectional view of a display panel according to the first embodiment of the present invention. FIG. 2 is a schematic diagram of incident light and reflected light of the first embodiment of the present invention. FIG. 3 is a curve diagram of reflectivity versus wavelength of the display panel of FIG. 1 under optical auxiliary layers of different film thicknesses. FIG. 4 is a distribution diagram of reflectivity of the display panel of FIG. 1 and b* in the CIELAB color space for optical auxiliary layers of different film thicknesses. FIG. 5 is a curve diagram of reflectivity versus wavelength of the display panel of FIG. 1 under different types of optical auxiliary layers. FIG. 6 is a distribution diagram of reflectivity of the display panel of FIG. 1 and b* in the CIELAB color space for different types of optical auxiliary layers. FIG. 7 is a schematic cross-sectional view of another variant embodiment of the optical auxiliary layer of FIG. 1. FIG8 is a schematic cross-sectional view of a display panel according to the second embodiment of the present invention. FIG9 is a schematic cross-sectional view of a display panel according to the third embodiment of the present invention. FIG10 is a schematic diagram of incident light and reflected light according to the third embodiment of the present invention. FIG11 is a distribution diagram of the reflectivity of the display panel of FIG9 and b* in the CIELAB color space for pixel electrodes of different film thicknesses. FIG12 is a schematic cross-sectional view of a display panel according to the fourth embodiment of the present invention. FIG13 is a schematic cross-sectional view of a display panel according to the fifth embodiment of the present invention. FIG14 is a distribution diagram of the reflectivity of the display panel of FIG13 and b* in the CIELAB color space for auxiliary metal layers of different film thicknesses. FIG15 is a schematic cross-sectional view of a display panel according to the sixth embodiment of the present invention. FIG. 16 is a schematic cross-sectional view of a display panel according to the seventh embodiment of the present invention. FIG. 17 is a schematic cross-sectional view of another variant embodiment of the optical auxiliary layer of FIG. 16 . FIG. 18 is a schematic cross-sectional view of a display panel according to the eighth embodiment of the present invention.

10: Display panel 101: First substrate 102: Second substrate 110: Insulation layer 130: Optical auxiliary layer 150: Display medium layer 170: Color filter layer 180: Common electrode layer EB: Ambient light FB: Front light PX: Pixel structure RB: Reflected light RE: Reflective electrode RML: Reflective metal layer T: Active element t1, t2: Film thickness TCL1: First transparent conductive layer TCL2: Second transparent conductive layer TH: Perforation Z: Direction

Claims (7)

A display panel comprises: a first substrate; a plurality of pixel structures, each comprising: a transparent conductive layer disposed on the first substrate; a reflective metal layer disposed between the first substrate and the transparent conductive layer and overlapping the transparent conductive layer; and at least one optical auxiliary layer overlapping the transparent conductive layer and the reflective metal layer and contacting at least one of the transparent conductive layer and the reflective metal layer, wherein the refractive index of the at least one optical auxiliary layer is greater than 1.85 or less than 1.65. ; a display medium layer; and a second substrate, which is overlapped with the first substrate, and the display medium layer is sandwiched between the first substrate and the second substrate, wherein the at least one optical auxiliary layer includes at least one auxiliary metal layer, and the at least one auxiliary metal layer is disposed between the reflective metal layer and the transparent conductive layer, and electrically contacts the reflective metal layer and the transparent conductive layer, and the refractive index of each of the at least one auxiliary metal layer and the reflective metal layer is less than the refractive index of the transparent conductive layer. The display panel as described in claim 1, wherein each of the pixel structures further comprises another transparent conductive layer disposed between the first substrate and the reflective metal layer, wherein the other transparent conductive layer overlaps the reflective metal layer and contacts the reflective metal layer. The display panel as described in claim 1, wherein the at least one auxiliary metal layer includes a first auxiliary metal layer, the first auxiliary metal layer contacts the reflective metal layer, and the refractive index of the first auxiliary metal layer is different from the refractive index of the reflective metal layer. The display panel as described in claim 3, wherein the at least one auxiliary metal layer further includes a second auxiliary metal layer, the second auxiliary metal layer is disposed on the first auxiliary metal layer and contacts the first auxiliary metal layer, and the refractive index of the second auxiliary metal layer and the reflective metal layer is greater than or less than the refractive index of the first auxiliary metal layer. A display panel as described in claim 4, wherein the film thickness of the reflective metal layer is greater than the film thickness of the first auxiliary metal layer, and the film thickness of the first auxiliary metal layer is greater than the film thickness of the second auxiliary metal layer. The display panel as described in claim 1, wherein the at least one optical auxiliary layer further includes at least one auxiliary insulating layer, and the transparent conductive layer is disposed between the at least one auxiliary metal layer and the at least one auxiliary insulating layer. The display panel as described in claim 1, wherein each of the pixel structures further comprises: an active element disposed on the second substrate; and a pixel electrode disposed on the second substrate and electrically connected to the active element, wherein a common electrode layer is disposed between the display medium layer and the first substrate, the active element and the pixel electrode are disposed between the display medium layer and the second substrate, and the transparent conductive layer, the reflective metal layer and the at least one optical auxiliary layer are disposed between the display medium layer and the first substrate.

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