Display device

Abstract

The present invention discloses a display device, comprising: a substrate, a driving element, a plurality of light-emitting elements and a cholesteric liquid crystal layer. The driving element is located on the substrate. The plurality of light-emitting elements are located on the substrate and are electrically connected to the driving element. The cholesteric liquid crystal layer is located on the plurality of light-emitting elements and has a first region and a second region, wherein the distance between the second region and the driving element is greater than the distance between the first region and the driving element, and the d / p value of the second region is greater than the d / p value of the first region, wherein d is the thickness of the cholesteric liquid crystal layer, and p is the pitch of the cholesteric liquid crystal molecules in the cholesteric liquid crystal layer.

Description

Technical Field

[0001] The invention relates to a display device. Background Art

[0002] Micro-LED display devices have the advantages of power saving, high efficiency, high brightness and fast response time. In order to achieve full color, one current approach is to place color conversion materials on the micro-LEDs that need to be converted to different colors. However, it can be found from the measured spectrum that the color conversion materials still have the problem of insufficient color conversion efficiency. For example, please refer to Figure 1 , Figure 1 The blue light emitted by the blue micro-LED in the existing display device is converted by the green and red conversion materials respectively, where the curve S1 represents the transmittance spectrum measured after the green conversion material conversion, and the curve S2 represents the transmittance spectrum measured after the red conversion material conversion. Figure 1 It can be seen that curves S1 and S2 still have obvious peaks near the blue light wavelength of about 460nm, indicating that there is still a phenomenon of blue light leakage and the color gamut is insufficient. Summary of the invention

[0003] The present invention provides a display device with improved color conversion efficiency and wider color gamut.

[0004] One embodiment of the present invention provides a display device, comprising: a substrate; a driving element located on the substrate; a plurality of light-emitting elements located on the substrate and electrically connected to the driving element; and a cholesterol-type liquid crystal layer located on the plurality of light-emitting elements and having a first region and a second region, wherein a distance between the second region and the driving element is greater than a distance between the first region and the driving element, and a d / p value of the second region is greater than a d / p value of the first region, wherein d is the thickness of the cholesterol-type liquid crystal layer, and p is the pitch of the cholesterol-type liquid crystal molecules in the cholesterol-type liquid crystal layer.

[0005] In an embodiment of the present invention, the first area and the second area respectively correspond to at least one light emitting element.

[0006] In one embodiment of the present invention, the display device further includes a color conversion layer located between the plurality of light emitting elements and the cholesteric liquid crystal layer.

[0007] In one embodiment of the present invention, the display device further includes a reflective polarizer located between the plurality of light emitting elements and the cholesteric liquid crystal layer.

[0008] In one embodiment of the present invention, the display device further includes a quarter wave plate located between the reflective polarizer and the cholesteric liquid crystal layer.

[0009] In one embodiment of the present invention, the angle between the transmission axis of the reflective polarizer and the slow axis of the quarter-wave plate is 45 degrees or 135 degrees.

[0010] In one embodiment of the present invention, the display device further comprises a compensation film located between the quarter wave plate and the cholesteric liquid crystal layer.

[0011] In one embodiment of the present invention, the display device further includes a filter layer located on the cholesteric liquid crystal layer.

[0012] Another embodiment of the present invention provides a display device, comprising: a circuit substrate; a plurality of light-emitting elements located on the circuit substrate and electrically connected to the circuit substrate; a cholesterol-type liquid crystal layer located on the plurality of light-emitting elements; a reflective polarizer located between the plurality of light-emitting elements and the cholesterol-type liquid crystal layer; a quarter-wave plate located between the reflective polarizer and the cholesterol-type liquid crystal layer; and a color conversion layer located between the plurality of light-emitting elements and the cholesterol-type liquid crystal layer.

[0013] In one embodiment of the present invention, the plurality of light emitting elements emit blue light.

[0014] In one embodiment of the present invention, the angle between the transmission axis of the reflective polarizer and the slow axis of the quarter-wave plate is 45 degrees or 135 degrees.

[0015] In one embodiment of the present invention, the color conversion layer is located between the plurality of light emitting elements and the reflective polarizer, between the reflective polarizer and the quarter wave plate, or between the quarter wave plate and the cholesteric liquid crystal layer.

[0016] In one embodiment of the present invention, the display device further comprises a compensation film located between the quarter wave plate and the cholesteric liquid crystal layer.

[0017] In one embodiment of the present invention, the compensation film is a +C plate.

[0018] In one embodiment of the present invention, the display device further includes a filter layer located on the cholesteric liquid crystal layer.

[0019] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a spectrum diagram measured after the blue light emitted by the blue micro-LED in the existing display device is converted by the green and red conversion materials respectively;

[0021] Figure 2A is a partial top view schematic diagram of a display device 10 according to an embodiment of the present invention;

[0022] Figure 2B is along Figure 2A A schematic cross-sectional view taken along the section line A-A';

[0023] Figure 2C yes Figure 2A A partial cross-sectional schematic diagram of a cholesteric liquid crystal layer 140 of a display device 20;

[0024] Figure 3A Yes Figure 2B The transmittance simulation result diagram of the display device 10 shown;

[0025] Figure 3B is a diagram showing the light intensity simulation results of the display device;

[0026] Figure 4 is a partial cross-sectional schematic diagram of a display device 20 according to an embodiment of the present invention;

[0027] Figure 5 is a partial cross-sectional schematic diagram of a display device 30 according to an embodiment of the present invention;

[0028] Figure 6 is a partial cross-sectional schematic diagram of a display device 40 according to an embodiment of the present invention;

[0029] Fig. 7A Yes Figure 2B The color shift simulation result diagram of the display device 10 shown;

[0030] Figure 7B Yes Figure 6 The color shift simulation result of the display device 40 is shown.

[0031] Explanation of symbols

[0032] 10, 20, 30, 40: Display device

[0033] 110: Substrate

[0034] 120: Driving element

[0035] 130, 131, 132, 133: Light-emitting elements

[0036] 140: Cholesteric liquid crystal layer

[0037] 1m, 1n: Area

[0038] A-A': Hatch line

[0039] A1: Area 1

[0040] A2: Second Area

[0041] A3: The third area

[0042] AH: Adhesive layer

[0043] B2: Blue Light

[0044] Bo: shoot out light

[0045] CF: Filter layer

[0046] CFb: Blue filter structure

[0047] CFg: Green filter structure

[0048] CFr: Red filter structure

[0049] CT: Color conversion layer

[0050] CV: Cover

[0051] d: thickness

[0052] D1, D2, D3: distance

[0053] Go: shoot out light

[0054] Gr: Blue light

[0055] p: pitch

[0056] Pc: Circularly polarized light

[0057] PS: Compensation film

[0058] Pw: P wave

[0059] Ro: emits light

[0060] RP: Reflective Polarizer

[0061] S1, S2, S3, S4, S5, S6: Curve

[0062] SPb, SPg, SPr: sub-pixel

[0063] T1, T2: Color conversion structure

[0064] WL: Wire

[0065] WP: Quarter Wave Plate

[0066] Ws: S wave DETAILED DESCRIPTION

[0067] In the accompanying drawings, for the sake of clarity, the thickness of layers, films, panels, regions, etc. is magnified. Throughout the specification, the same reference numerals represent the same elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it may be directly on or connected to another element, or an intermediate element may also exist. On the contrary, when an element is referred to as being "directly on" or "directly connected to" another element, there is no intermediate element. As used herein, "connection" may refer to physical and / or electrical connection. Furthermore, "electrical connection" or "coupling" may be the presence of other elements between two elements.

[0068] It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or portions, these elements, components, regions, layers and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or portion from another element, component, region, layer or portion. Therefore, the first "element", "component", "region", "layer" or "portion" discussed below may be referred to as a second element, component, region, layer or portion without departing from the teachings of this document.

[0069] In addition, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe the relationship of one element to another element, as shown in the figures. It should be understood that relative terms are intended to include different orientations of the device in addition to the orientation shown in the figures. For example, if the device in one figure is turned over, the elements described as being on the "lower" side of the other elements will be oriented on the "upper" side of the other elements. Therefore, the exemplary term "lower" can include both "lower" and "upper" orientations, depending on the particular orientation of the figure. Similarly, if the device in one figure is turned over, the elements described as being "lower" or "below" other elements will be oriented as being "above" the other elements. Therefore, the exemplary terms "lower" or "below" can include both above and below orientations.

[0070] Taking into account the measurement in question and the specific amount of error associated with the measurement (i.e., the limitations of the measurement system), the terms "about", "approximately", or "substantially" as used herein include the stated value and the average value within an acceptable deviation range of the particular value determined by one of ordinary skill in the art. For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, the terms "about", "approximately", or "substantially" as used herein may select a more acceptable deviation range or standard deviation depending on the optical property, etching property, or other property, and may not apply to all properties with one standard deviation.

[0071] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and the present invention, and will not be interpreted as an idealized or overly formal meaning unless explicitly defined as such herein.

[0072] Figure 2A is a partial top view of a display device 10 according to an embodiment of the present invention. Figure 2B is along Figure 2A A schematic cross-sectional view taken along the section line AA'. Figure 2C yes Figure 2A 1 is a partial cross-sectional diagram of a cholesteric liquid crystal layer 140 of a display device 10. In order to make the expression of the drawings more concise, Figure 2A The substrate 110 , the driving element 120 , the light emitting element 130 and the cholesteric liquid crystal layer 140 of the display device 10 are schematically illustrated, and other components are omitted.

[0073] Please refer to FIG. 2A to FIG. 2C The display device 10 includes: a substrate 110; a driving element 120, located on the substrate 110; a plurality of light-emitting elements 130, located on the substrate 110 and electrically connected to the driving element 120; and a cholesterol-type liquid crystal layer 140, located on the plurality of light-emitting elements 130, and having a first area A1 and a second area A2, wherein a distance D2 between the second area A2 and the driving element 120 is greater than a distance D1 between the first area A1 and the driving element 120, and a d / p value of the second area A2 is greater than a d / p value of the first area A1.

[0074] In this embodiment, the substrate 110 may be a circuit substrate, and the components or circuits required by the display device 10 may be disposed in the substrate 110, such as a driving component 120, a switching component, a storage capacitor, a power line, a driving signal line, a timing signal line, a current compensation line, a detection signal line, etc. In addition, the substrate 110 may also include a plurality of pads located on its surface, and these pads may be used to electrically connect the components or circuits disposed in the substrate 110 with the components or circuits outside the substrate 110, such as the driving component 120 or the light emitting component 130.

[0075] In this embodiment, the driving element 120 can be disposed on the same side of the substrate 110 as the light emitting element 130, but is not limited thereto. In some embodiments, the driving element 120 can be disposed on the side of the substrate 110 opposite to the light emitting element 130 or other appropriate locations.

[0076] In the present embodiment, the light emitting element 130 may be a micro light emitting diode (Micro-LED), and the light emitting element 130 is, for example, manufactured on a growth substrate, transferred to the substrate 110 through a mass transfer process, and electrically connected to the driving element 120 through the wire WL, but not limited thereto. In some embodiments, the light emitting element 130 may be electrically connected to a plurality of pads of the substrate 110 through, for example, solder or conductive glue, and then electrically connected to the driving element 120 through these pads. The light emitting element 130 may include a light emitting element 131, a light emitting element 132, and a light emitting element 133, wherein the light emitting elements 131, 132, and 133 may all be blue light emitting diodes, but not limited thereto. In other embodiments, the light emitting elements 131, 132, and 133 may have different light colors as needed. In some embodiments, the light emitting elements 131, 132, and 133 may respectively constitute sub-pixels SPr, SPg, and SPb of the display device 10, and the sub-pixels SPr, SPg, and SPb may together constitute a pixel of the display device 10.

[0077] Please refer to Figure 2C , the cholesteric liquid crystal molecules in the cholesteric liquid crystal layer 140 have a spiral structure and have a pitch p. When the cholesteric liquid crystal layer 140 has a thickness d, the greater the ratio d / p of the thickness d to the pitch p, the higher the reflectivity. For example, according to the simulation results of the present invention, when circularly polarized light is incident on the cholesteric liquid crystal layer 140 with a pitch p of 0.295 μm, the corresponding relationship between the d / p value and the maximum reflectivity is shown in Table 1 below.

[0078] Table 1

[0079] d / p 5 7 9 11 13 15 17 d(μm) 1.473 2.062 2.651 3.240 3.829 4.418 5.007 Maximum reflectivity 58％ 78％ 88％ 93％ 95％ 96％ 96％

[0080] Please refer to Figure 2A Since the distance D2 between the second area A2 of the cholesteric liquid crystal layer 140 and the driving element 120 is greater than the distance D1 between the first area A1 and the driving element 120, the brightness reduction of the light emitting element 130 corresponding to the second area A2 due to the resistance voltage drop (IR drop) will be greater than the brightness reduction of the light emitting element 130 corresponding to the first area A1 due to the IR drop. Therefore, in this embodiment, the reflectivity of the second area A2 of the cholesteric liquid crystal layer 140 can be made greater than the reflectivity of the first area A1, thereby compensating the light intensity of the light emitting element 130 corresponding to the second area A2, so that the light emitting element 130 can present similar or substantially the same brightness in the first area A1 and the second area A2. In other words, the d / p value of the second area A2 can be made greater than the d / p value of the first area A1, that is, the thickness of the second area A2 is greater than the thickness of the first area A1. By making each area of ​​the cholesteric liquid crystal layer 140 have different thicknesses, the light intensity of each area can be adjusted, thereby improving the overall brightness uniformity of the display device 10.

[0081] In some embodiments, the cholesteric liquid crystal layer 140 may further include a third region A3, and a distance D3 between the third region A3 and the driving element 120 is greater than a distance D2 between the second region A2 and the driving element 120. Similarly, by making the d / p value (or thickness) of the third region A3 greater than the d / p value (or thickness) of the second region A2, the reflectivity of the third region A3 can be greater than the reflectivity of the second region A2, thereby compensating for the brightness reduction of the light-emitting element 130 corresponding to the third region A3 due to IR drop, so that the light-emitting element 130 can present similar or substantially the same brightness in the first region A1, the second region A2, and the third region A3.

[0082] According to the simulation results of the present embodiment, the d / p value, reflectivity, and light intensity before and after compensation by the cholesteric liquid crystal layer 140 of the first area A1, the second area A2, and the third area A3 are shown in Table 2. As can be seen from Table 2, the light intensity after compensation of the first area A1, the second area A2, and the third area A3 is substantially the same, indicating that the brightness uniformity of the display device 10 can be effectively improved.

[0083] Table 2

[0084]

[0085]

[0086] In some embodiments, the cholesteric liquid crystal layer 140 can be further divided into more regions according to the brightness distribution of the display screen of the display device 10, and each region can correspond to one or more light-emitting elements 130, and multiple light-emitting elements 130 in the same region can have similar pre-compensation light intensities to perform the same degree of light intensity compensation. The number of light-emitting elements 130 corresponding to each region can be the same or different. In some embodiments, each region can correspond to one light-emitting element 131, one light-emitting element 132, or one light-emitting element 133, thereby individually adjusting the brightness of the emitted light Ro, Go, Bo of the sub-pixels SPr, SPg, and SPb.

[0087] Please refer to Figure 2BIn some embodiments, the display device 10 may further include a color conversion layer CT, which may be located between the light emitting elements 131, 132, 133 and the cholesterol-type liquid crystal layer 140, so that the light emitting elements 131, 132, 133 may be equipped with different color conversion materials as needed to form full-color pixels. The material of the color conversion layer CT may include quantum dots (QD), fluorescent materials, or wavelength conversion materials with similar properties, such as silicates, silicon nitrides, sulfides, quantum dots, or garnets, so that the colored light emitted by the light emitting elements 131, 132, 133 may be converted into light with desired colors. For example, the color conversion layer CT may include color conversion structures T1 and T2, wherein the color conversion structure T1 may be disposed corresponding to the light-emitting element 131 to convert the blue light emitted by the light-emitting element 131 into, for example, red light, and the color conversion structure T2 may be disposed corresponding to the light-emitting element 132 to convert the blue light emitted by the light-emitting element 132 into, for example, green light, and the blue light emitted by the light-emitting element 133 does not need to be color converted. In this way, the light-emitting elements 131, 132, and 133 may constitute a full-color pixel.

[0088] Since the cholesteric liquid crystal molecules obey the Bragg reflection law, the cholesteric liquid crystal layer 140 can be made to reflect incident light of a specific wavelength by adjusting the pitch p of the liquid crystal molecules. In the present embodiment, the cholesteric liquid crystal layer 140 can be configured to reflect the blue light emitted by the light emitting elements 131 and 132. For example, the cholesteric liquid crystal layer 140 can have a region 1m and a region 1n, wherein the blue light emitted by the light emitting element 131 and leaving the color conversion structure T1 without being converted by the color conversion structure T1 can be reflected by the region 1m of the cholesteric liquid crystal layer 140 back to the color conversion structure T1 for further light color conversion, and the blue light emitted by the light emitting element 132 and leaving the color conversion structure T2 without being converted by the color conversion structure T2 can be reflected by the region 1n of the cholesteric liquid crystal layer 140 back to the color conversion structure T2 for further light color conversion.

[0089] In some embodiments, the display device 10 may further include an adhesive layer AH, which may be located between the light emitting element 130 and the color conversion layer CT to increase the bonding between the color conversion layer CT and the light emitting element 130. In some embodiments, the adhesive layer AH may also be located between the light emitting elements 131, 132, and 133.

[0090] In some embodiments, the display device 10 may further include a reflective polarizer RP, and the reflective polarizer RP may be located between the light-emitting elements 131, 132, 133 and the cholesteric liquid crystal layer 140. In some embodiments, the reflective polarizer RP may be located between the color conversion layer CT and the cholesteric liquid crystal layer 140. In other words, the color conversion layer CT may be located between the light-emitting elements 131, 132, 133 and the reflective polarizer RP, but is not limited thereto. The P wave in the non-polarized light emitted by the light-emitting elements 131, 132, 133 will pass through the reflective polarizer RP, and the S wave may be reflected back to the color conversion layer CT by the reflective polarizer RP.

[0091] In some embodiments, the display device 10 may further include a quarter wave plate WP, and the quarter wave plate WP may be located between the reflective polarizer RP and the cholesteric liquid crystal layer 140 to convert the P wave passing through the reflective polarizer RP into circularly polarized light. In some embodiments, the angle between the transmission axis of the reflective polarizer RP and the slow axis of the quarter wave plate WP may be 45 degrees or 135 degrees, so that the reflection spectrum of the cholesteric liquid crystal layer 140 can match the light spectrum of the blue light-emitting diode. Since the reflection of the cholesteric liquid crystal layer 140 has polarization selectivity, the light utilization rate of the light-emitting elements 131, 132, and 133 can be improved by setting the reflective polarizer RP and the quarter wave plate WP.

[0092] In some embodiments, the display device 10 may further include a filter layer CF, and the filter layer CF may be located on the cholesteric liquid crystal layer 140. The filter layer CF may include, for example, a red filter structure CFr, a green filter structure CFg, and a blue filter structure CFb, wherein the red filter structure CFr may overlap the light emitting element 131, the green filter structure CFg may overlap the light emitting element 132, and the blue filter structure CFb may overlap the light emitting element 133. In some embodiments, the display device 10 may further include a cover plate CV, which may be located on the filter layer CF, and the cover plate CV may be a transparent substrate, and its material may include glass, quartz, organic polymer or other suitable materials.

[0093] Figure 3A Yes Figure 2B The transmittance simulation result of the display device 10 shown in FIG. 1 is shown in FIG. 2 . Curve S3 indicates that the peak of the blue light emitted by the light emitting element 132 of the display device 10 is located at about 450 nm. Curve S4 indicates the variation of the transmittance measured for the sub-pixel SPg including the light emitting element 132 with wavelength. It can be seen from curve S4 that Figure 2BIn the embodiment, the blue light B2 emitted by the light emitting element 132 is first converted by the color conversion structure T2 of the color conversion layer CT, then the P wave Pw passes through the reflective polarizer RP and the S wave Ws is reflected by the reflective polarizer RP, then the P wave Pw passes through the quarter wave plate WP and is converted into circularly polarized light Pc, then the region 1n of the cholesterol-type liquid crystal layer 140 reflects the blue light Gr in the circularly polarized light Pc back to the color conversion structure T2 for another color conversion, so that the proportion of blue light in the emitted light Go of the sub-pixel SPg can be significantly reduced, that is, the phenomenon of blue light leakage can be eliminated. Similarly, the emitted light Ro of the sub-pixel SPr including the light emitting element 131 can also have a reduced proportion of blue light.

[0094] Figure 3B is a light intensity simulation result of the display device, wherein curve S5 shows the change of light intensity versus wavelength measured for the sub-pixel SPg, and curve S6 shows the change of light intensity versus wavelength measured when the cholesteric liquid crystal layer 140, the reflective polarizer RP, and the quarter-wave plate WP are not provided in the sub-pixel SPg. Figure 3B It can be seen that the green light intensity of curve S5 is about 1.3 times higher than that of curve S6, indicating that the color conversion efficiency is improved by 30%, and curve S5 has no obvious peak near 450nm, while curve S6 still has an obvious peak near 450nm, indicating that the display device 10 can indeed eliminate the phenomenon of blue light leakage, thereby effectively improving the color conversion efficiency. In addition, according to the simulation results, its Rec.2020 color gamut (color coverage) can also be increased from 77% to more than 88%.

[0095] Below, use Figures 4 to 6 Continue to describe other embodiments of the present invention, and continue to use FIG. 2A to FIG. 2C The component numbers and related contents of the embodiments are the same, wherein the same number is used to represent the same or similar components, and the description of the same technical contents is omitted. For the description of the omitted parts, please refer to FIG. 2A to FIG. 2C The embodiments of the present invention will not be repeated in the following description.

[0096] Figure 4 1 is a partial cross-sectional schematic diagram of a display device 20 according to an embodiment of the present invention. The display device 20 includes: a substrate 110; a plurality of light emitting elements 130, which are located on the substrate 110 and are electrically connected to the substrate 110; a cholesteric liquid crystal layer 140, which is located on the plurality of light emitting elements 130; a reflective polarizer RP, which is located between the plurality of light emitting elements 130 and the cholesteric liquid crystal layer 140; a quarter wave plate WP, which is located between the reflective polarizer RP and the cholesteric liquid crystal layer 140; a color conversion layer CT, which is located between the plurality of light emitting elements 130 and the cholesteric liquid crystal layer 140; a filter layer CF, which is located on the cholesteric liquid crystal layer 140; and a cover plate CV, which is located on the filter layer CF.

[0097] With FIG. 2A to FIG. 2B Compared with the display device 10 shown, Figure 4 The difference of the display device 20 shown is that the color conversion layer CT of the display device 20 can be located between the reflective polarizer RP and the quarter wave plate WP. In this way, the blue light emitted by the light emitting element 130 can first pass through the reflective polarizer RP to filter out the P wave, then pass through the color conversion layer CT for color conversion, then pass through the quarter wave plate WP to be converted into circularly polarized light, and then the cholesterol liquid crystal layer 140 reflects the blue light back to the color conversion layer CT for color conversion again, thereby improving the color conversion efficiency of the display device 20.

[0098] Figure 5 1 is a partial cross-sectional schematic diagram of a display device 30 according to an embodiment of the present invention. The display device 30 includes: a substrate 110; a plurality of light emitting elements 130, which are located on the substrate 110 and are electrically connected to the substrate 110; a cholesteric liquid crystal layer 140, which is located on the plurality of light emitting elements 130; a reflective polarizer RP, which is located between the plurality of light emitting elements 130 and the cholesteric liquid crystal layer 140; a quarter wave plate WP, which is located between the reflective polarizer RP and the cholesteric liquid crystal layer 140; a color conversion layer CT, which is located between the plurality of light emitting elements 130 and the cholesteric liquid crystal layer 140; a filter layer CF, which is located on the cholesteric liquid crystal layer 140; and a cover plate CV, which is located on the filter layer CF.

[0099] With FIG. 2A to FIG. 2B Compared with the display device 10 shown, Figure 5 The difference of the display device 30 shown is that the color conversion layer CT of the display device 20 can be located between the quarter wave plate WP and the cholesteric liquid crystal layer 140. In this way, the blue light emitted by the light emitting element 130 can first pass through the reflective polarizer RP to filter out the P wave, then pass through the quarter wave plate WP to convert it into circularly polarized light, then pass through the color conversion layer CT to perform color conversion, and then the cholesteric liquid crystal layer 140 reflects the blue light back to the color conversion layer CT for color conversion again, thereby improving the color conversion efficiency of the display device 30.

[0100] Figure 61 is a partial cross-sectional schematic diagram of a display device 40 according to an embodiment of the present invention. The display device 40 includes: a substrate 110; a plurality of light emitting elements 130, which are located on the substrate 110 and are electrically connected to the substrate 110; a cholesteric liquid crystal layer 140, which is located on the plurality of light emitting elements 130; a color conversion layer CT, which is located between the plurality of light emitting elements 130 and the cholesteric liquid crystal layer 140; a reflective polarizer RP, which is located between the color conversion layer CT and the cholesteric liquid crystal layer 140; a quarter wave plate WP, which is located between the reflective polarizer RP and the cholesteric liquid crystal layer 140; a filter layer CF, which is located on the cholesteric liquid crystal layer 140; and a cover plate CV, which is located on the filter layer CF.

[0101] With FIG. 2A to FIG. 2B Compared with the display device 10 shown, Figure 6 The difference of the display device 40 shown is that the display device 40 may further include a compensation film PS, which may be located between the quarter wave plate WP and the cholesteric liquid crystal layer 140 , and the compensation film PS may be a +C plate, but is not limited thereto.

[0102] Fig. 7A Yes Figure 2B The color shift simulation result of the display device 10 is shown. Figure 7B Yes Figure 6 The color shift simulation result of the display device 40 is shown. Fig. 7A The simulation results from Figure 7B It can be seen that the color shift of the display device 40 is significantly improved, especially the color difference at a large viewing angle is greatly reduced, indicating that the compensation film PS is indeed helpful in improving the color shift.

[0103] In summary, the display device of the present invention reflects the light that has not been successfully converted by the color conversion layer back to the color conversion layer by setting a cholesterol liquid crystal layer, and at the same time improves the light utilization rate of the light-emitting element by setting a reflective polarizer and a quarter-wave plate, so that the display device can have higher color conversion efficiency and a wider color gamut. In addition, the display device of the present invention can generate different light intensity gains by using the different reflectivities of the cholesterol liquid crystal at different d / p values. In this way, different degrees of light intensity compensation can be performed on each area with different light intensities, thereby effectively improving the brightness uniformity of the display device.

[0104] Although the present invention is disclosed in conjunction with the above embodiments, they are not intended to limit the present invention. Any ordinary technician in the technical field may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the attached claims.

Claims

1. A display device, comprising: substrate; A driving element, located on the substrate; A plurality of light emitting elements, located on the substrate and electrically connected to the driving element; A cholesteric liquid crystal layer, located on the plurality of light-emitting elements, and having a first region and a second region; as well as a color conversion layer, located between the plurality of light emitting elements and the cholesteric liquid crystal layer, Among them, the distance between the second zone and the driving element is greater than the distance between the first zone and the driving element, and the d / p value of the second zone is greater than the d / p value of the first zone, wherein d is the thickness of the cholesterol-type liquid crystal layer, and p is the pitch of the cholesterol-type liquid crystal molecules in the cholesterol-type liquid crystal layer. 2 . The display device as claimed in claim 1 , wherein the first area and the second area respectively correspond to at least one of the light-emitting elements.

3. The display device as claimed in claim 1, further comprising a reflective polarizer located between the plurality of light-emitting elements and the cholesteric liquid crystal layer.

4. The display device as claimed in claim 3, further comprising a quarter wave plate located between the reflective polarizer and the cholesteric liquid crystal layer. 5 . The display device as claimed in claim 4 , wherein the angle between the transmission axis of the reflective polarizer and the slow axis of the quarter-wave plate is 45 degrees or 135 degrees.

6. The display device as claimed in claim 4, further comprising a compensation film located between the quarter wave plate and the cholesteric liquid crystal layer.

7. The display device as claimed in claim 1, further comprising a filter layer located on the cholesteric liquid crystal layer.

8. A display device, comprising: Circuit board; A plurality of light emitting elements are located on the circuit substrate and electrically connected to the circuit substrate; a cholesteric liquid crystal layer, located on the plurality of light emitting elements; A reflective polarizer, located between the plurality of light-emitting elements and the cholesteric liquid crystal layer; A quarter wave plate, located between the reflective polarizer and the cholesteric liquid crystal layer; as well as The color conversion layer is located between the plurality of light emitting elements and the cholesteric liquid crystal layer, wherein the plurality of light emitting elements emit blue light, and the cholesteric liquid crystal layer is configured to reflect light whose color has not been successfully converted by the color conversion layer back to the color conversion layer. 9 . The display device as claimed in claim 8 , wherein the angle between the transmission axis of the reflective polarizer and the slow axis of the quarter-wave plate is 45 degrees or 135 degrees.

10. The display device as claimed in claim 8, wherein the color conversion layer is located between the plurality of light-emitting elements and the reflective polarizer, between the reflective polarizer and the quarter-wave plate, or between the quarter-wave plate and the cholesteric liquid crystal layer.

11. The display device according to claim 8, further comprising a compensation film located between the quarter wave plate and the cholesteric liquid crystal layer. The display device according to claim 11 , wherein the compensation film is a +C plate.

13. The display device as claimed in claim 8, further comprising a filter layer located on the cholesteric liquid crystal layer.

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