Display device

Abstract

To provide a display device which has uniform brightness of an image and can suppress occurrence of moire.SOLUTION: A display device includes a display panel including a first substrate, a second substrate, and a liquid crystal layer having polymer dispersion liquid crystals, a plurality of light-emitting elements, and a light guide element. The light guide element includes a third base material, a transparent layer having a refractive index lower than that of the third base material, and a transparent adhesive layer provided so as to be overlapped with the transparent layer, the plurality of light-emitting elements is arranged adjacent to a first side face of the third base material, first thickness of the transparent layer is reduced toward a second side face on a side opposite to the first side face from the first side face, and second thickness of the transparent adhesive layer is increased toward the second side face from the first side face.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present embodiment relates to a display device. [Background technology]

[0002] A display device has been proposed that uses polymer dispersed liquid crystal (PDLC) to switch between a scattering state in which incident light is scattered and a transmission state in which incident light is transmitted. Transparent display devices using PDLC adopt an edge light method in which a light source is placed at the edge of a light guide plate. However, when the edge light method is used in a PDLC display device, there is a problem in that the brightness of the display surface decreases with increasing distance from the light source.

[0003] In order to solve such problems, a display device has been developed in which a light guide element having a transparent layer with a low refractive index arranged in an isosceles triangle shape is provided on a liquid crystal panel (see Patent Documents 3 and 4).

[0004] However, the display devices shown in Patent Documents 3 and 4 have a new problem in that moire occurs between the transparent layer and pixels in the isosceles triangle shape. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-032411 A [Patent Document 2] JP 2020-016724 A [Patent Document 3] JP 2022-174556 A [Patent Document 4] International Publication No. 2022 / 158477 [Patent Document 5] International Publication No. 2022 / 158478 [Patent Document 6] International Publication No. 2020 / 022112 [Patent Document 7] JP 2020-148955 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of this embodiment is to provide a display device that can provide uniform image luminance and suppress the occurrence of moire. [Means for solving the problem]

[0007] A display device according to an embodiment includes: A display panel including a first substrate, a second substrate, and a liquid crystal layer having a polymer dispersed liquid crystal; A plurality of light emitting elements; A light guide element; Equipped with The light guide element is A third substrate; a transparent layer having a refractive index lower than the refractive index of the third substrate; A transparent adhesive layer provided so as to overlap the transparent layer; Equipped with the plurality of light emitting elements are disposed adjacent to a first side surface of the third substrate; a first thickness of the transparent layer decreases from the first side to a second side opposite the first side; A second thickness of the transparent adhesive layer increases from the first side to the second side. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a display device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of the display panel shown in FIG. [Diagram 3] FIG. 3 is an exploded perspective view showing a main part of the display device. [Figure 4]FIG. 4 is a cross-sectional view showing an example of a schematic configuration of a display device. [Diagram 5] FIG. 5 is a cross-sectional view showing an example of a schematic configuration of a display device. [Figure 6] FIG. 6 shows the results of a simulation showing the relationship between the thickness and the reflectance of a material layer having a low refractive index. [Figure 7] FIG. 7 is a diagram showing the relationship between the reflectance and thicknesses of 300 nm, 600 nm, 800 nm, and 1000 nm in the simulation results shown in FIG. [Figure 8] FIG. 8 is a diagram showing the relationship between the wavelength (λ) [nm] of light, the incident angle (°) of light, and the transmittance. [Figure 9] FIG. 9 is a diagram showing the relationship between the thickness and transmittance of the transparent layer. [Figure 10] FIG. 10 is a diagram showing the relationship between the thickness and transmittance of the transparent layer obtained based on FIG. [Figure 11] FIG. 11 is a cross-sectional view showing an example of a schematic configuration of a transparent layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. Note that the disclosure is merely an example, and those who are skilled in the art can easily come up with appropriate modifications while maintaining the gist of the invention, which are naturally included in the scope of the present invention. In addition, in order to make the explanation clearer, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments described in this specification are not general, but are embodiments describing the same or corresponding special technical features of the present invention.

[0011] In this embodiment, the first direction X, the second direction Y, and the third direction Z are perpendicular to each other, but may intersect at an angle other than 90 degrees. The direction toward the tip of the arrow of the third direction Z is defined as up or upward, and the direction opposite to the direction toward the tip of the arrow of the third direction Z is defined as down or downward. The first direction X, the second direction Y, and the third direction Z may also be called the X direction, the Y direction, and the Z direction, respectively.

[0012] Furthermore, in the case of "a second member above the first member" and "a second member below the first member," the second member may be in contact with the first member or may be located away from the first member. In the latter case, a third member may be interposed between the first and second members. On the other hand, in the case of "a second member above the first member" and "a second member below the first member," the second member is in contact with the first member.

[0013] Also, it is assumed that an observation position for observing the display device is located at the tip side of the arrow in the third direction Z, and a planar view refers to a view from this observation position toward the XY plane defined by the first direction X and the second direction Y. A cross-sectional view refers to a view of a cross section of the display device in the XZ plane defined by the first direction X and the third direction Z, or in the YZ plane defined by the second direction Y and the third direction Z.

[0014] [Embodiment] FIG. 1 is a plan view showing a schematic configuration of a display device according to an embodiment. In this embodiment, a liquid crystal display device to which a polymer dispersed liquid crystal is applied will be described as an example of the display device DSP. The display device DSP includes a display panel PNL, an IC chip ICP, and a wiring board FPC1.

[0015] The display panel PNL includes a substrate SUB1, a substrate SUB2, a liquid crystal layer LC, and a seal SAL. The substrates SUB1 and SUB2 are formed in the shape of flat plates parallel to the XY plane. The substrates SUB1 and SUB2 overlap each other in a planar view. The substrates SUB1 and SUB2 are bonded together by the seal SAL. The liquid crystal layer LC is held between the substrates SUB1 and SUB2, and is sealed by the seal SAL.

[0016] As shown enlarged and schematic in FIG. 1, the liquid crystal layer LC includes a polymer-dispersed liquid crystal including a polymer PLM and liquid crystal molecules LCM. In one example, the polymer PLM is a liquid crystal polymer. The polymer PLM is formed in stripes extending along a first direction X. The liquid crystal molecules LCM are dispersed in gaps in the polymer PLM, and are oriented such that their major axes are aligned along the first direction X. Each of the polymer PLM and the liquid crystal molecules LCM has optical anisotropy or refractive index anisotropy. The responsiveness of the polymer PLM to an electric field is lower than the responsiveness of the liquid crystal molecules LCM to an electric field.

[0017] In one example, the alignment direction of the polymer PLM hardly changes regardless of the presence or absence of an electric field. On the other hand, the alignment direction of the liquid crystal molecules LCM changes in response to an electric field when a high voltage equal to or higher than a threshold value is applied to the liquid crystal layer LC. When no voltage is applied to the liquid crystal layer LC, the optical axes of the polymer PLM and the liquid crystal molecules LCM are parallel to each other, and light incident on the liquid crystal layer LC is transmitted through the liquid crystal layer LC with almost no scattering within the liquid crystal layer LC (transparent state). When a voltage is applied to the liquid crystal layer LC, the optical axes of the polymer PLM and the liquid crystal molecules LCM cross each other, and light incident on the liquid crystal layer LC is scattered within the liquid crystal layer LC (scattered state).

[0018] The display panel PNL includes a display area DA for displaying an image and a frame-shaped non-display area NDA surrounding the display area DA. The seal SAL is located in the non-display area NDA. The display area DA includes pixels PX arranged in a matrix in the first direction X and the second direction Y.

[0019] 1, each of the pixels PX includes a switching element SW, a pixel electrode PE, a common electrode CE, a liquid crystal layer LC, etc. The switching element SW is formed of, for example, a thin film transistor (TFT), and is electrically connected to the scanning line GL and the signal line SL.

[0020] Although not shown in the figure, the multiple scanning lines GL extend along a first direction X and are arranged side by side along a second direction Y. As shown in Fig. 1, one scanning line GL is electrically connected to the switching elements SW in each of the pixels PX arranged in the first direction X.

[0021] Although not shown, the multiple signal lines SL extend in a direction parallel to the second direction Y and are arranged side by side along the first direction X. As shown in Fig. 1, one signal line SL is electrically connected to the switching elements SW in each of the pixels PX arranged in the second direction Y. The signal lines SL intersect with the scanning lines GL.

[0022] Each of the pixels PX occupies an area defined by two adjacent signal lines SL and two adjacent scanning lines GL. That is, the pixels PX are arranged at a predetermined pitch along each of the first direction X and the second direction Y. The pitch of the pixels PX along the first direction X is equal to the pitch of the signal lines SL. The pitch of the pixels PX along the second direction Y is equal to the pitch of the scanning lines GL.

[0023] The pixel electrodes PE are electrically connected to the switching elements SW. Each pixel electrode PE faces a common electrode CE, and drives the liquid crystal layer LC (particularly, liquid crystal molecules LCM) by an electric field generated between the pixel electrodes PE and the common electrode CE.

[0024] The scanning lines GL, signal lines SL, switching elements SW, and pixel electrodes PE are provided on a substrate SUB1. The capacitance CS is formed, for example, between an electrode having the same potential as the common electrode CE and an electrode having the same potential as the pixel electrode PE.

[0025] The substrate SUB1 has ends E11 and E14 extending along the first direction X, and ends E12 and E13 extending along the second direction Y. The substrate SUB2 has ends E21 and E24 extending along the first direction X, and ends E22 and E23 extending along the second direction Y.

[0026] 1, the ends E12 and E22, the ends E13 and E23, and the ends E14 and E24 overlap each other in a plan view, but they do not have to overlap. The end E21 is located between the end E11 and the display area DA in a plan view. The substrate SUB1 has an extension area Ex between the end E11 and the end E21.

[0027] The IC chip ICP and the wiring board FPC1 are each connected to the extension region Ex. The IC chip ICP has built-in, for example, a display driver that outputs signals necessary for image display. The wiring board FPC1 is a bendable flexible printed circuit board. The IC chip ICP may be connected to the wiring board FPC1. The IC chip ICP and the wiring board FPC1 may read out signals from the display panel PNL, but mainly function as a signal source that supplies signals to the display panel PNL.

[0028] FIG. 2 is a cross-sectional view showing a schematic configuration of the display panel shown in FIG. The substrate SUB1 includes a base material BA1, an insulating layer INS1, an insulating layer INS2, a capacitance electrode CSE, a switching element SW, a pixel electrode PE, and an alignment film AL1. The substrate SUB1 further includes the scanning lines GL and the signal lines SL shown in FIG.

[0029] The base material BA1 is made of a light-transmitting material. The base material BA1 has a main surface (lower surface) B1A and a main surface (upper surface) B1B opposite to the main surface 10A. The switching element SW is disposed on the main surface B1B.

[0030] The insulating layer INS1 covers the switching element SW. The capacitance electrode CSE is located between the insulating layer INS1 and the insulating layer INS2. The pixel electrode PE is disposed for each pixel PX on the insulating layer INS2. The pixel electrode PE is electrically connected to the switching element SW through an opening OP of the capacitance electrode CSE. The pixel electrode PE overlaps with the capacitance electrode CSE with the insulating layer INS2 sandwiched therebetween to form a capacitance CS of the pixel PX. The alignment film AL1 covers the pixel electrode PE.

[0031] The substrate SUB2 includes a base material BA2, a light-shielding layer BM, a common electrode CE, and an alignment film AL2.

[0032] The base material BA2 is formed of a light-transmitting material. The base material BA2 has a main surface (lower surface) B2A and a main surface (upper surface) B2B opposite to the main surface B2A. The main surface B2A of the base material BA2 faces the main surface B2B of the base material BA1. The light-shielding layer BM and the common electrode CE are disposed on the main surface B2A. The light-shielding layer BM is located, for example, directly above the switching element SW and directly above the scanning line GL and the signal line SL (not shown).

[0033] The common electrode CE is disposed across multiple pixels PX and directly covers the light-shielding layer BM. The common electrode CE faces the pixel electrodes PE. The common electrode CE is electrically connected to the capacitive electrode CSE and has the same potential as the capacitive electrode CSE. The alignment film AL2 covers the common electrode CE. The liquid crystal layer LC is located between the principal surface B1B and the principal surface B2A and is in contact with the alignment films AL1 and AL2.

[0034] The base material BA1 and the base material BA2 are insulating base materials made of glass, plastic, etc. The principal surface B1A, the principal surface B1B, the principal surface B2A, and the principal surface B2B are surfaces substantially parallel to the XY plane.

[0035] The insulating layer INS1 is formed of a transparent insulating material such as silicon oxide, silicon nitride, silicon oxynitride, acrylic resin, etc. In one example, the insulating layer INS1 is a combination of an inorganic insulating layer and an organic insulating layer. The insulating layer INS2 is an inorganic insulating layer such as silicon nitride.

[0036] The capacitance electrode CSE, the pixel electrode PE, and the common electrode CE are transparent electrodes formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0037] The light-shielding layer BM is, for example, a conductive layer having a lower resistance than the common electrode CE. In one example, the light-shielding layer BM is made of an opaque metal material such as molybdenum (Mo), aluminum (Al), tungsten (W), titanium (Ti), or silver (Ag).

[0038] The alignment films AL1 and AL2 are horizontal alignment films having an alignment regulating force substantially parallel to the XY plane. In one example, the alignment films AL1 and AL2 are aligned along the first direction X. The alignment treatment may be a rubbing treatment or a photo-alignment treatment.

[0039] FIG. 3 is an exploded perspective view showing a main part of the display device. The display device DSP includes a plurality of light emitting elements LD and a light guide element LG in addition to the display panel PNL. The substrate SUB1, the substrate SUB2, and the light guide element LG are arranged in the third direction Z in this order.

[0040] The light emitting elements LD are arranged at intervals in the first direction X. The light emitting elements LD are connected to a wiring board FPC2. The light emitting elements LD are, for example, light emitting diodes. Although not described in detail, the light emitting elements LD include a red light emitting element, a green light emitting element, and a blue light emitting element. Light emitted from the light emitting elements LD travels along the direction of the arrow indicating the second direction Y.

[0041] The light guide element LG includes a base material BA3 and a transparent layer LRI. The base material BA3 is formed of a material having light-transmitting properties. The base material BA3 is an insulating base material such as glass or plastic, and has a refractive index n1. In one example, the base material BA3 is a single base material, not a combination of multiple base materials.

[0042] The base material BA3 has a main surface (lower surface) B3A, a main surface (upper surface) B3B opposite to the main surface B3A, a first side surface SS1, a second side surface SS2, a third side surface SS3, and a fourth side surface SS4. The main surfaces B3A and B3B are substantially parallel to the XY plane. The main surface B3A faces the main surface B2B of the base material BA2.

[0043] The first side surface SS1 faces the multiple light-emitting elements LD. The first side surface SS1 and the fourth side surface SS4 extend in the first direction X. The second side surface SS2 and the third side surface SS3 extend in the second direction Y. The first side surface SS1 and the fourth side surface SS4 face each other. The second side surface SS2 and the third side surface SS3 face each other. The second side surface SS2 and the third side surface SS3 intersect with the first side surface SS1.

[0044] As described later, the base material BA3 is bonded to the base material BA2 with a transparent layer LRI sandwiched therebetween. In the example shown in Fig. 3, the first side surface SS1 is located directly above the end E21 of the substrate SUB2, but may be located directly above the extension region Ex or may be located further outward than the end E11.

[0045] The transparent layer LRI is disposed across the main surface B3A. The transparent layer LRI is a so-called solid film. However, the thickness of the transparent layer LRI varies from the first side surface SS1 to the fourth side surface SS4. The film thickness of the transparent layer LRI will be described in detail later.

[0046] The substrate BA3 is formed of an organic material such as glass, polymethylmethacrylate (PMMA), or polycarbonate (PC). The transparent layer LRI is formed of an organic material such as a siloxane-based resin or a fluorine-based resin. The transparent layer LRI has a refractive index n2 lower than the refractive index n1 of the substrate BA3. The refractive index n1 of the substrate BA3 is approximately 1.5, and the refractive index n2 of the transparent layer LRI is approximately 1.0 to 1.4.

[0047] 4 is a cross-sectional view showing an example of a schematic configuration of a display device. In the display device DSP in FIG. 4, only components necessary for explanation are shown.

[0048] A laminate of a transparent layer LRI and a transparent adhesive layer TMS is provided between the substrate BA2 and the substrate BA3. The thickness of the transparent layer LRI is defined as thickness tc. The thickness tc increases from the first side surface SS1 toward the fourth side surface SS4. The thicknesses tc at the first side surface SS1 and the fourth side surface SS4 are defined as thickness tc1 and thickness tc2, respectively. The thickness tc2 is greater than the thickness tc1 (tc2>tc1).

[0049] The thickness of the transparent adhesive layer TMS is defined as tk, and the thickness tk decreases from the first side surface SS1 to the fourth side surface SS4. The thicknesses tk at the first side surface SS1 and the fourth side surface SS4 are defined as tk1 and tk2, respectively. The thickness tk2 is smaller than the thickness tk1 (tc2 <tc1)。

[0050] The sum of the thickness tc of the transparent layer LRI and the thickness tk of the transparent adhesive layer TMS is constant over the first side surface SS1 and the fourth side surface SS4, that is, the distance between the display panel PNL and the base material BA3 is constant.

[0051] Here, the function of the transparent layer LRI will be described. The transparent layer LRI has a function of guiding the light emitted from the light emitting element LD and incident on the first side surface SS1 to the fourth side surface SS4.

[0052] Fig. 5 is a diagram showing a cross-sectional configuration of an example of a schematic configuration of a display device. In the display device DSP shown in Fig. 5, the density of the transparent layer LRI changes depending on the distance from the light emitting element LD. This will be described in detail below.

[0053] The light LT emitted from the light emitting element LD is incident on the first side surface SS1 of the base material BA3. The light LT incident on the first side surface SS1 is guided inside the base material BA3 while being reflected by the main surface B3B and the transparent layer LRI. The main surface B3B is the interface between the base material BA3 and the air layer.

[0054] As described above, the light LT is reflected by the principal surface B3B and the transparent layer LRI. However, when the light LT passes through the region NLR of the principal surface B3A where the transparent layer LRI is not provided, the light LT passes through the region NLR and enters the display panel PNL. Note that the light LT may also pass through the transparent layer LRI and enter the display panel PNL.

[0055] By being reflected by the transparent layer LRI, the light LT can be guided from the first side surface SS1, which is the incident surface, to the fourth side surface SS4 opposite to the first side surface SS1. The light LT that is incident on the display panel PNL in the region NLR is diffused or transmitted by the liquid crystal layer LC of the display panel PNL. As a result, an image is displayed on the display device DSP.

[0056] The density of the transparent layer LRI is changed according to the distance from the light emitting element LD. Specifically, the area of ​​the transparent layer LRI is increased as it is closer to the light emitting element LD. As a result, in the area close to the light emitting element LD, the amount of light LT reflected by the transparent layer LRI becomes greater than the amount of light LT incident on the display panel PNL.

[0057] On the other hand, as described above, the area of ​​the transparent layer LRI is smaller in the region far from the light emitting element LD, so that in the region far from the light emitting element LD, the amount of light LT incident on the display panel PNL is greater than the amount of light LT reflected by the transparent layer LRI.

[0058] In order to change the area of ​​the transparent layer LRI, it is preferable to provide the transparent layer LRI as, for example, a triangular strip. The base of the triangle is located in a region close to the light-emitting element LD. The apex of the triangle is located in a region far from the light-emitting element LD.

[0059] With the above configuration, it is possible to guide the light LT to an area far from the light emitting element LD, and it is possible to make the brightness of the image displayed on the display device DSP uniform.

[0060] However, as described above, a new problem occurs in that moire occurs between the transparent layer LRI and the pixel PX.

[0061] Therefore, in this embodiment, as shown in FIG. 4, the transparent layer LRI is formed as a so-called solid film, and the thickness tc of the transparent layer LRI is reduced as it becomes farther from the light emitting element LD. This makes it possible to obtain the same effect as that of changing the area of ​​the transparent layer LRI. Furthermore, since the transparent layer LRI is a solid film, no moire occurs. From the above, the display device DSP of this embodiment can not only make the luminance of the displayed image uniform, but also suppress the occurrence of moire.

[0062] As described above, the refractive index of the transparent layer LRI is lower than that of the substrate BA3. When electromagnetic waves are totally reflected between materials with different refractive indices, a phenomenon occurs in which the electromagnetic waves seep from the material with the higher refractive index to the material with the lower refractive index. The electromagnetic waves that seep out are called evanescent waves. When the electromagnetic waves are light, they are called evanescent light.

[0063] Fig. 6 shows the results of a simulation showing the relationship between thickness and reflectance in a low refractive index material layer. In Fig. 6, the horizontal axis is the thickness tc (Thickness [nm]) of the low refractive index material layer, and the vertical axis is the normalized reflectance. The light used in the simulation has a wavelength λ of 550 nm and is incident on the low refractive index material layer at a viewing angle of 70°.

[0064] FIG. 7 is a diagram showing the relationship between the reflectance and thicknesses of 300 nm, 600 nm, 800 nm, and 1000 nm in the simulation results shown in FIG.

[0065] In Fig. 7, for example, the transmittance at a transparent layer LRI thickness tc of 300 nm and a viewing angle of about 70° is 48%. When other viewing angle components are taken into consideration, there are places where the transmittance is high and places where it is low, but the viewing angle is set to 70° over the entire transparent layer LRI. The transmittance at this time is the transmittance of the entire transparent layer LRI.

[0066] 6 and 7, as the thickness of the low refractive index material layer, i.e., the transparent layer LRI, increases, the reflectance increases. In other words, as the thickness of the transparent layer LRI decreases, the reflectance decreases. This is because, when the thickness of the transparent layer LRI is small, the light incident on the transparent layer LRI leaks out as evanescent light, which decreases the reflectance.

[0067] However, by utilizing the seepage effect of such evanescent light, it is possible to improve the transmittance by making the light seep out in the region far from the light emitting element LD, i.e., the region close to the fourth side surface SS4. On the other hand, the light is totally reflected in the region close to the light emitting element LD, i.e., the region close to the first side surface SS1. This allows the transparent layer LRI to adjust the amount of light reaching the liquid crystal layer LC of the display panel PNL.

[0068] Fig. 8 is a diagram showing the relationship between the wavelength (λ) [nm] of light, the incident angle (°) of light, and the transmittance. The transmittance in Fig. 8 is a normalized transmittance, which is obtained by subtracting the normalized reflectance from 1 (transmittance = 1 - reflectance).

[0069] 8 shows that the transmittance is 0.7 (70%) at an incident angle of about 70°. In other words, when light is incident on the transparent layer LRI at an incident angle of 70°, the proportion of the light that is reflected is 0.3 (30%), and the proportion of the light that is transmitted is 0.7 (70%).

[0070] Fig. 9 is a diagram showing the relationship between the thickness and transmittance of the transparent layer. Fig. 10 is a diagram showing the relationship between the thickness and transmittance of the transparent layer obtained based on Fig. 9. It can also be seen from Fig. 9 and Fig. 10 that as the thickness tc of the transparent layer LRI increases, the transmittance decreases, and as the thickness of the transparent layer LRI decreases, the transmittance increases.

[0071] As described above in Figures 6 to 10, as the thickness tc of the transparent layer LRI increases, the reflectance increases. In other words, as the thickness tc of the transparent layer LRI increases, the transmittance decreases. On the other hand, as the thickness of the transparent layer LRI decreases, the reflectance decreases. In other words, as the thickness of the transparent layer LRI decreases, the transmittance increases.

[0072] 4, if the thickness tc of the transparent layer LRI is large in the region close to the light-emitting element LD, the transparent layer LRI has a higher reflectance than transmittance, and therefore the amount of light reflected by the transparent layer LRI increases in the region close to the light-emitting element LD. In the region close to the light-emitting element LD, the transparent layer LRI has a smaller transmittance, and therefore the amount of light reaching the liquid crystal layer LC of the display panel PNL decreases.

[0073] On the other hand, if the thickness tc of the transparent layer LRI is small up to the region far from the light-emitting element LD, the transparent layer LRI has a higher transmittance than reflectance, and therefore the amount of light that passes through the transparent layer LRI increases in the region far from the light-emitting element LD. Therefore, the amount of light that reaches the liquid crystal layer LC of the display panel PNL increases in the region far from the light-emitting element LD.

[0074] As described above, in the configuration shown in FIG. 4, the light incident on the display panel PNL can be adjusted by changing the thickness tc of the transparent layer LRI.

[0075] In order to compensate for the change in thickness tc of the transparent layer LRI, a transparent adhesive layer TMS is provided, which makes it possible to keep the distance between the display panel PNL and the base material BA3 constant.

[0076] It is preferable that the thickness tc of the transparent layer LRI changes continuously as shown in Fig. 4. However, for manufacturing reasons, it may be difficult to change the thickness tc continuously. In that case, it is possible to change the thickness tc in a stepwise manner.

[0077] Fig. 11 is a cross-sectional view showing an example of a schematic configuration of a transparent layer. The transparent layer LRI shown in Fig. 11 has a thickness that gradually decreases from the first side surface SS1 to the fourth side surface SS4. In Fig. 11, the thickness of the transparent layer LRI is changed in 11 steps from the first side surface SS1 to the fourth side surface SS4.

[0078] The thickness tc of the transparent layer LRI at the first side surface SS1 is set to tc1 as described above. The length of the region R011 of the transparent layer LRI having the thickness tc1 along the direction parallel to the second direction Y is set to lc011.

[0079] The thickness tc of the transparent layer LRI at the fourth side surface SS4 is set to tc2 as described above. The length of the region R021 of the transparent layer LRI having the thickness tc2 along the direction parallel to the second direction Y is set to lc021.

[0080] Regions R012, R013, R014, R015, R016, R017, R018, R019, and R020 are provided, each having a thickness tc and a length lc different from each other from region R011 to region R021.

[0081] The thicknesses tc of region R012, region R013, region R014, region R015, region R016, region R017, region R018, region R019, and region R020 are thickness tc012, thickness tc013, thickness tc014, thickness tc015, thickness tc016, thickness tc017, thickness tc018, thickness tc019, and thickness tc020, respectively.

[0082] The lengths lc of regions R012, R013, R014, R015, R016, R017, R018, R019, and R020 are length lc012, length lc013, length lc014, length lc015, length lc016, length lc017, length lc018, length lc019, and length lc020, respectively.

[0083] The percentages of thickness tc011, thickness tc012, thickness tc013, thickness tc014, thickness tc015, thickness tc016, thickness tc017, thickness tc018, thickness tc019, thickness tc020, and thickness tc021 to the whole are, for example, 5%, 10%, 10%, 10%, 10%, 10%, 10%, 10%, 10%, 10%, and 5%, respectively. As a more specific example, thickness tc011, thickness tc012, thickness tc013, thickness tc014, thickness tc015, thickness tc016, thickness tc017, thickness tc018, thickness tc019, thickness tc020, and thickness tc021 may be 1000 nm, 725 nm, 524 nm, 443 nm, 362 nm, 287 nm, 229 nm, 172 nm, 115 nm, 57 nm, and 0 nm, respectively.

[0084] As shown in Figures 10 and 11, when the thicknesses tc011 to tc021 are 1000 nm, 725 nm, 524 nm, 443 nm, 362 nm, 287 nm, 229 nm, 172 nm, 115 nm, 57 nm, and 0 nm, respectively, the transmittances of region R011, region R012, region R013, region R014, region R015, region R016, region R017, region R018, region R019, region R020, and region R021 are 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0, respectively.

[0085] The ratios of the length lc011, the length lc012, the length lc013, the length lc014, the length lc015, the length lc016, the length lc017, the length lc018, the length lc019, the length lc020, and the length lc021 may be determined in the same manner as the ratio of the thickness lc.

[0086] The values ​​and ratios of the length lc and thickness tc described above are merely examples and can be changed as appropriate based on the size of the display device DSP, the material of the transparent layer LRI, and the like.

[0087] The thickness tk of the transparent adhesive layer TMS is changed stepwise in the same manner as the transparent layer LRI, except that, as described above, the thickness tk of the transparent adhesive layer TMS is determined so that the sum of the thicknesses of the transparent layer LRI and the transparent adhesive layer TMS is constant.

[0088] In the display device DSP of this embodiment, the thickness of the transparent layer LRI decreases as the distance from the light-emitting element LD increases. In areas close to the light-emitting element LD, the transparent layer LRI reflects light. In areas far from the light-emitting element LD, the amount of transmitted light increases due to the seepage effect of evanescent light. This makes it possible to make the brightness of the image displayed on the display device DSP uniform.

[0089] Since the transparent layer LRI is a so-called solid film, no moire occurs between the pixel PX and the signal line SL in particular. Therefore, in the display device DSP of this embodiment, not only can the brightness of the image be made uniform, but also the occurrence of moire can be suppressed.

[0090] In the present disclosure, the first side surface SS1 and the fourth side surface SS4 are also referred to as the first side surface and the second side surface, respectively. The thickness tc of the transparent layer LRI and the thickness tk of the transparent adhesive layer TMS are also referred to as the first thickness and the second thickness, respectively.

[0091] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0092] BA3...substrate, DSP...display device, LD...light emitting element, LG...light guide element, LRI...transparent layer, LT...light, PNL...display panel, SS1...first side, SS2...second side, SS3...third side, SS4...fourth side, TMS...transparent adhesive layer.

Claims

1. A display panel including a first substrate, a second substrate, and a liquid crystal layer having a polymer dispersed liquid crystal; A plurality of light emitting elements; A light guide element; Equipped with The light guide element is A third substrate; a transparent layer having a refractive index lower than the refractive index of the third substrate; A transparent adhesive layer provided so as to overlap the transparent layer; Equipped with the plurality of light emitting elements are disposed adjacent to a first side surface of the third substrate; a first thickness of the transparent layer decreases from the first side to a second side opposite the first side; A display device, wherein the second thickness of the transparent adhesive layer increases from the first side to the second side.

2. The display device according to claim 1 , wherein the sum of the first thickness and the second thickness is constant from the first side surface to the second side surface.

3. The display device of claim 1 , wherein the first thickness decreases stepwise from the first side to the second side.

4. The display device according to claim 1 , wherein the transparent layer is made of a siloxane-based resin or a fluorine-based resin.

5. 2. The display device according to claim 1, wherein the third substrate has a refractive index of 1.5, and the transparent layer has a refractive index of 1.0 to 1.4.

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