Reflective display panel

Abstract

A reflective display panel including a first substrate, a second substrate, a liquid crystal layer, a reflective layer, at least one overcoat layer and a light diffusion layer is provided. A first substrate and a second substrate are overlapped with each other. The liquid crystal layer is disposed between the first substrate and the second substrate. The reflective layer is disposed on the first substrate. The at least one overcoat layer is disposed on the second substrate, and located between the second substrate and the liquid crystal layer. The at least one overcoat layer is provided with a plurality of microlens structures, and the plurality of microlens structures overlap the reflective layer. The light diffusion layer is disposed on the second substrate, and overlaps the reflective layer and the plurality of microlens structures.

Description

[Technical Field]

[0001] The present invention relates to a display panel, and more particularly to a reflective display panel. [Previous Technology]

[0002] Reflective display panels rely on external light sources for illumination. To prevent reflections from external light sources (such as ambient light) from affecting the viewing quality of the screen, anti-glare polarizers with haze or polarizers with diffusion adhesive are typically applied to the surface of reflective display panels. However, external light tends to diverge after passing through these polarizers and enters the liquid crystal layer at an angle significantly different from the viewing direction. Because the phase retardation of the liquid crystal layer for large-angle incident external light is not optimized, dark-state light leakage in reflective display panels increases, resulting in decreased display contrast. [Summary of the Invention]

[0003] The present invention provides a reflective display panel with anti-glare properties, which can also maintain display contrast.

[0004] The reflective display panel of the present invention includes a first substrate, a second substrate, a liquid crystal layer, a reflective layer, at least one cladding layer, and a light diffuser layer. The first substrate and the second substrate are disposed overlapping each other. The liquid crystal layer is disposed between the first substrate and the second substrate. The reflective layer is disposed on the first substrate. At least one cladding layer is disposed on the second substrate and located between the second substrate and the liquid crystal layer. The at least one cladding layer has a plurality of microlens structures, and these microlens structures overlap the reflective layer. The light diffuser layer is disposed on the second substrate and overlaps the reflective layer and the plurality of microlens structures.

[0005] In one embodiment of the present invention, at least one coating layer of the above-mentioned reflective display panel includes a first coating layer and a second coating layer. The first coating layer has a plurality of microcavities embedded therein, and the second coating layer fills these microcavities to form a plurality of microlens structures.

[0006] In one embodiment of the present invention, the refractive index of the second coating layer of the above-mentioned reflective display panel is greater than the refractive index of the first coating layer.

[0007] In one embodiment of the present invention, at least one coating layer of the above-mentioned reflective display panel includes a first coating layer and a second coating layer. The second coating layer is disposed between the first coating layer and the liquid crystal layer, and is provided with a plurality of microlens structures.

[0008] In one embodiment of the present invention, the refractive index of the second coating layer of the above-mentioned reflective display panel is greater than the refractive index of the liquid crystal layer.

[0009] In one embodiment of the present invention, the above-mentioned reflective display panel further includes a common electrode layer disposed on the second substrate and located between the first coating layer and the second coating layer.

[0010] In one embodiment of the present invention, at least one coating layer of the above-mentioned reflective display panel is a coating layer. The coating layer has a plurality of microgrooves recessed from the surface on its surface facing the liquid crystal layer, and the liquid crystal layer fills these microgrooves to form a plurality of microlens structures.

[0011] In one embodiment of the present invention, the refractive index of the coating layer of the above-mentioned reflective display panel is less than the refractive index of the liquid crystal layer.

[0012] In one embodiment of the present invention, the above-mentioned reflective display panel further includes a common electrode layer disposed on the second substrate and located between the coating layer and the liquid crystal layer.

[0013] In one embodiment of the present invention, the above-mentioned reflective display panel further includes a plurality of filter patterns disposed on a second substrate and arranged along intersecting first and second directions. Each filter pattern has a first width and a second width along the first and second directions, respectively. The first width is smaller than the second width. The width of each microlens structure along the first direction is greater than or equal to 10 micrometers and less than or equal to the first width of each filter pattern.

[0014] Based on the above, in a reflective display panel according to an embodiment of the present invention, a reflective layer for reflecting external light is provided on one side of the liquid crystal layer, and a light diffusion layer for suppressing glare is provided on the other side. Since the coating layer disposed between the liquid crystal layer and the light diffusion layer has multiple microlens structures, external light diverging after passing through the light diffusion layer can be deflected by these microlens structures to pass through the liquid crystal layer in a near-positive or shorter path. Accordingly, dark-state light leakage generated by the diverging external light after passing through the liquid crystal layer can be effectively reduced, thereby improving the display contrast of the reflective display panel.

Implementation Method

[0015] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the drawings. Wherever possible, the same element symbols are used in the drawings and description to denote the same or similar parts.

[0016] FIG1 is a cross-sectional schematic diagram of a reflective display panel according to a first embodiment of the present invention. Referring to FIG1, the reflective display panel 10 includes a first substrate 101, a second substrate 102, and a liquid crystal layer 200. The first substrate 101 and the second substrate 102 are disposed overlapping each other along direction D3. The liquid crystal layer 200 is disposed between the first substrate 101 and the second substrate 102. In this embodiment, the first substrate 101 is, for example, a pixel array substrate, which may include multiple scan lines (not shown), multiple data lines (not shown), and multiple pixel structures PX.

[0017] For example, multiple scan lines and multiple data lines can be arranged to intersect each other and define multiple pixel regions PA. Each of these pixel regions PA can have multiple pixel structures PX. The multiple pixel structures PX can be arranged in multiple columns and multiple rows along directions D1 and D2 respectively. That is, these pixel structures PX (or multiple pixel regions PA) can be arrayed on the first substrate 101.

[0018] The pixel structure PX may include an active element (not shown) and a pixel electrode PE. The active element may be electrically connected to the pixel electrode PE, a data line, and a scan line, but is not limited thereto. In this embodiment, the pixel electrode PE of the pixel structure PX is, for example, a reflective electrode. That is, the pixel electrode PE of this embodiment may also serve as the reflective layer RFL of the pixel structure PX, but is not limited thereto. In other embodiments, the pixel electrode PE may be a light-transmitting electrode, and the pixel structure PX may additionally include a reflective layer.

[0019] Furthermore, the reflective display panel 10 may also include a plurality of filter patterns FP1 to FP3 and a light-shielding pattern layer BM. Specifically, the light-shielding pattern layer BM may have a plurality of openings OP that overlap with a plurality of pixel structures PX. Alternatively, these openings OP of the light-shielding pattern layer BM may define a plurality of pixel areas PA of the reflective display panel 10. A plurality of filter patterns FP1 to FP3 may be respectively provided within the plurality of openings OP of the light-shielding pattern layer BM. For example, in this embodiment, filter patterns FP1, FP2, and FP3 may each have different filter colors, such as red, green, and blue, but are not limited thereto.

[0020] The reflective display panel 10 further includes a light diffusion layer 150 and a polarizer POL, disposed on the surface 102s of the second substrate 102. The light diffusion layer 150 is located between the polarizer POL and the second substrate 102. The light diffusion layer 150 can reduce the glare caused by external light L (e.g., ambient light) reflected from the surface 102s of the second substrate 102, thus reducing the impact on the viewing quality of the image. The material of the light diffusion layer 150 includes, for example, polycarbonate (PC), acrylic acid, or a photosensitive adhesive doped with diffusion particles, wherein the material of the diffusion particles includes, for example, polymethyl methacrylate (PMMA) or polystyrene (PS), but the present invention is not limited thereto. It is particularly noteworthy that after passing through the light diffusion layer 150, the external light L will diverge into multiple diverging light rays Ls that deviate from the original light path direction. The aforementioned diverging light rays Ls refer, for example, to light rays that deviate more from the normal direction (e.g., direction D3) of the surface 102s of the second substrate 102 after passing through the light diffusion layer 150.

[0021] Since some of the divergent light rays Ls are incident on the liquid crystal layer 200 at a relatively large angle, their light path length in the liquid crystal layer 200 is also relatively long. For the divergent light rays Ls incident on the liquid crystal layer 200 at a large angle, the phase delay generated by the liquid crystal layer 200 is not optimized. Therefore, the divergent light rays Ls incident at a large angle cannot be effectively absorbed by the polarizer POL after passing through the liquid crystal layer 200 operating in the dark state, resulting in light leakage, i.e., dark state light leakage. It should be noted that the divergent light rays Ls passing through the liquid crystal layer 200 will pass through the liquid crystal layer 200 again after being reflected by the reflective layer RFL and will leave the reflective display panel 10 from one side of the second substrate 102 or be absorbed by the polarizer POL.

[0022] To solve the above problems, the reflective display panel 10 of this embodiment has a plurality of microlens structures ML between the light diffusion layer 150 and the liquid crystal layer 200, and these microlens structures ML overlap the reflective layer RFL and the light diffusion layer 150 along the direction D3. The microlens structures ML can deflect the light paths of diverging light rays Ls with different divergence angles, so that the diverging light rays Ls with large angles can enter the liquid crystal layer 200 at a small angle or a closer angle to the positive direction (e.g., direction D3) after passing through the microlens structures ML. In this way, the diverging light rays Ls can pass through the liquid crystal layer 200 with a shorter light path. That is, the liquid crystal layer 200 can change the polarization state of the diverging light rays Ls with optimized phase delay, so that they can be effectively absorbed by the polarizer POL when displaying a dark state, thereby improving the problem of light leakage in the dark state.

[0023] In this embodiment, a cladding layer OC1 and a cladding layer OC2 may be provided on the second substrate 102. The cladding layer OC1 has multiple microcavities CV embedded in it, and the cladding layer OC2 fills these microcavities CV to form multiple microlens structures ML. The refractive index of the cladding layer OC2 may be greater than the refractive index of the cladding layer OC1. For example, in this embodiment, the multiple microlens structures ML formed by the cladding layer OC2 are first formed on the first sublayer OC1a of the cladding layer OC1, and then the second sublayer OC1b of the cladding layer OC1 is covered to form a stacked structure in which these microlens structures ML are embedded in the cladding layer OC1, but this is not a limitation.

[0024] In this embodiment, the materials of the first sublayer OC1a and the second sublayer OC1b of the cladding layer OC1 may be selectively the same, but are not limited thereto. In other embodiments, the materials of the first sublayer OC1a and the second sublayer OC1b may be different, as long as the refractive index of each of the first sublayer OC1a and the second sublayer OC1b is less than the refractive index of the cladding layer OC2.

[0025] Further, the reflective display panel 10 may also include a common electrode layer CEL disposed on the second substrate 102. In this embodiment, the common electrode layer CEL is located between the liquid crystal layer 200 and the cladding layer OC1. The electric field formed between the common electrode layer CEL and the pixel electrode PE is used to drive multiple liquid crystal molecules (not shown) of the liquid crystal layer 200 to rotate, so that they form an arrangement state corresponding to different electric field intensities, thereby changing the polarization state of light passing through the liquid crystal layer 200. The electric field between the pixel electrode PE of different pixel structures PX and the common electrode layer CEL can be individually controlled, so that the light reflected by the reflective layer RFL of different pixel structures PX has different polarization states, thereby allowing different pixel areas PA to have different display brightness.

[0026] Figure 2 is a bottom view schematic diagram of multiple microlens structures arranged on multiple filter patterns according to one embodiment of the present invention. Figure 3 is a bottom view schematic diagram of multiple microlens structures arranged on multiple filter patterns according to another embodiment of the present invention. Referring to Figure 2, in one embodiment, filter patterns FP1, FP2, and FP3 each have a width W1 along direction D1 and a width W2 along direction D2, wherein the width W1 is smaller than the width W2. Specifically, the width W of the microlens structure ML along direction D1 can be greater than or equal to 10 micrometers and less than or equal to the width W1 of each filter pattern.

[0027] In the embodiment of FIG. 2, multiple microlens structures ML can be arranged in multiple columns and rows along directions D1 and D2, respectively. However, the present invention is not limited thereto. Referring to FIG. 3, in another embodiment, multiple microlens structures ML-A can be arranged in multiple columns along direction D1, and any microlens structure ML-A in each column will be staggered in direction D2 by any microlens structure ML-A in the adjacent column. More specifically, these microlens structures ML-A can be arranged in a honeycomb pattern on multiple filter patterns FP1~FP3, but are not limited thereto. In other embodiments not shown, the arrangement of the microlens structures can be adjusted according to actual needs.

[0028] Other embodiments will be listed below to illustrate this disclosure in detail, wherein the same components will be marked with the same symbols, and the description of the same technical content will be omitted. For the omitted parts, please refer to the foregoing embodiments, and they will not be repeated below.

[0029] FIG4 is a cross-sectional schematic diagram of a reflective display panel according to a second embodiment of the present invention. Referring to FIG4, the difference between the reflective display panel 20 of this embodiment and the reflective display panel 10 of FIG1 is that the positions of the microlens structures are different. For example, in the reflective display panel 20 of this embodiment, the coating layer OC2 forming multiple microlens structures ML-B is located between the coating layer OC1-A and the liquid crystal layer 200. In this embodiment, a common electrode layer CEL is provided between the coating layer OC1-A and the coating layer OC2.

[0030] More specifically, in this embodiment, multiple microlens structures ML-B can be formed on the common electrode layer CEL and directly covered by the liquid crystal layer 200. Therefore, in this embodiment, the refractive index of the cladding layer OC2 must be greater than the refractive index of the liquid crystal layer 200 so that the diverging light Ls can produce the optical path deflection effect as described in the previous embodiment after passing through the microlens structure ML-B. That is, the diverging light Ls can pass through the liquid crystal layer 200 with a shorter optical path after passing through the microlens structure ML-B. Therefore, the liquid crystal layer 200 can change the polarization state of the diverging light Ls with optimized phase delay, so that it can be effectively absorbed by the polarizer POL when displaying a dark state, thereby improving the problem of light leakage in the dark state. The refractive index of the aforementioned liquid crystal layer 200 is, for example, the average refractive index of the liquid crystal layer 200.

[0031] FIG5 is a cross-sectional schematic diagram of a reflective display panel according to a third embodiment of the present invention. Referring to FIG5, the difference between the reflective display panel 30 of this embodiment and the reflective display panel 20 of FIG4 is that the formation method of the microlens structure is different. Specifically, in this embodiment, the coating layer OC of the reflective display panel 30 has a plurality of microgrooves MG recessed from the surface OCs on the surface OCs facing the liquid crystal layer 200, and the liquid crystal layer 200 fills these microgrooves MG to form a plurality of microlens structures ML-C. In this embodiment, the common electrode layer CEL-A is located between the coating layer OC and the liquid crystal layer 200, and conformally covers the surface OCs of the coating layer OC.

[0032] It is particularly noteworthy that, in this embodiment, the refractive index of the cladding layer OC is less than that of the liquid crystal layer 200, so that the diverging light Ls, after passing through the microlens structure ML-C, produces the optical path deflection effect as described in the previous embodiment. That is, the diverging light Ls can pass through the liquid crystal layer 200 with a shorter optical path after passing through the microlens structure ML-C. Therefore, the liquid crystal layer 200 can change the polarization state of the diverging light Ls with optimized phase delay, so that it can be effectively absorbed by the polarizer POL when displaying a dark state, thereby improving the problem of light leakage in the dark state. The aforementioned refractive index of the liquid crystal layer 200 is, for example, the average refractive index of the liquid crystal layer 200.

[0033] In summary, in a reflective display panel according to an embodiment of the present invention, a reflective layer for reflecting external light is provided on one side of the liquid crystal layer, and a light diffusion layer for suppressing glare is provided on the other side. Since the coating layer disposed between the liquid crystal layer and the light diffusion layer has multiple microlens structures, external light diverging after passing through the light diffusion layer can be deflected by these microlens structures to pass through the liquid crystal layer in a near-forward or shorter path. Accordingly, dark-state light leakage generated by the diverging external light after passing through the liquid crystal layer can be effectively reduced, thereby improving the display contrast of the reflective display panel. [Simplified Explanation of the Diagram]

[0034] FIG1 is a cross-sectional schematic diagram of a reflective display panel according to a first embodiment of the present invention. FIG2 is a bottom view schematic diagram of a plurality of microlens structures arranged on a plurality of filter patterns according to an embodiment of the present invention. FIG3 is a bottom view schematic diagram of a plurality of microlens structures arranged on a plurality of filter patterns according to another embodiment of the present invention. FIG4 is a cross-sectional schematic diagram of a reflective display panel according to a second embodiment of the present invention. FIG5 is a cross-sectional schematic diagram of a reflective display panel according to a third embodiment of the present invention.

Claims

1. A reflective display panel, comprising: The first substrate and the second substrate are disposed overlapping each other; A liquid crystal layer is disposed between the first substrate and the second substrate; A reflective layer is disposed on the first substrate; At least one cladding layer is disposed on the second substrate and located between the second substrate and the liquid crystal layer. The at least one cladding layer has a plurality of microlens structures that overlap the reflective layer. A light diffusion layer is disposed on the second substrate and overlaps the reflective layer and the microlens structures. A plurality of filter patterns are disposed on the second substrate and arranged along a first direction and a second direction that intersect each other. Each of the filter patterns has a first width and a second width along the first direction and the second direction, respectively. The first width is smaller than the second width. The width of each of the microlens structures along the first direction is greater than or equal to 10 micrometers and less than or equal to the first width of each of the filter patterns.

2. The reflective display panel as claimed in claim 1, wherein the at least one coating layer includes a first coating layer and a second coating layer, the first coating layer having embedded a plurality of microcavities, and the second coating layer filling the microcavities to form the microlens structure.

3. The reflective display panel as claimed in claim 2, wherein the refractive index of the second coating layer is greater than the refractive index of the first coating layer.

4. The reflective display panel as claimed in claim 1, wherein the at least one coating layer includes a first coating layer and a second coating layer, the second coating layer being disposed between the first coating layer and the liquid crystal layer, and having the microlens structure.

5. The reflective display panel as claimed in claim 4, wherein the refractive index of the second coating layer is greater than the refractive index of the liquid crystal layer.

6. The reflective display panel as described in claim 4, further comprising: A common electrode layer is disposed on the second substrate and located between the first cladding layer and the second cladding layer.

7. The reflective display panel as claimed in claim 1, wherein the at least one coating layer is a coating layer having a plurality of microgrooves recessed from the surface on a surface facing the liquid crystal layer, and the liquid crystal layer filling the microgrooves to form the microlens structure.

8. The reflective display panel as claimed in claim 7, wherein the refractive index of the coating layer is less than the refractive index of the liquid crystal layer.

9. The reflective display panel as described in claim 7, further comprising: A common electrode layer is disposed on the second substrate and located between the cladding layer and the liquid crystal layer.

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