Display device

Abstract

The display device includes a first display panel, a second display panel, and a first light source, the first display panel and the second display panel are disposed in contact with each other, the first polymer dispersed liquid crystal layer is provided between the first alignment film and the second alignment film, and the second polymer dispersed liquid crystal layer is provided between the first alignment film and the second alignment film. The second polymer dispersed liquid crystal layer is provided between the third alignment film and the fourth alignment film, and a first thickness between the first alignment film and the second alignment film and a second thickness between the third alignment film and the fourth alignment film are each 2 [mu] m or less.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of priority from prior Japanese patent application No. 2023-103231 filed on June 23, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] An embodiment of the utility model relates to a display device. Background Art

[0004] In recent years, a display device using a polymer-dispersed liquid crystal capable of switching between a scattering state in which incident light is scattered and a transmissive state in which the incident light is transmitted has been proposed. Utility Model Content

[0005] An object of this embodiment is to provide a display device capable of reducing the voltage of a polymer dispersed liquid crystal layer and suppressing a decrease in scattering brightness.

[0006] A display device according to one embodiment includes:

[0007] A first display panel comprises a first substrate, a second substrate, and a first polymer dispersed liquid crystal layer disposed between the first substrate and the second substrate;

[0008] A second display panel comprising a third substrate, a fourth substrate, and a second polymer dispersed liquid crystal layer disposed between the third substrate and the fourth substrate; and

[0009] a first light source, disposed at an end of the first display panel,

[0010] The first substrate comprises:

[0011] a plurality of first signal lines;

[0012] a plurality of first scanning lines;

[0013] a plurality of first pixels, divided by the plurality of first signal lines and the plurality of first scan lines;

[0014] A plurality of first switch elements, disposed in the plurality of first pixels; and

[0015] The first orientation film,

[0016] The second substrate includes a second alignment film facing the first alignment film.

[0017] The third substrate comprises:

[0018] a plurality of second signal lines;

[0019] a plurality of second scanning lines;

[0020] a plurality of second pixels, divided by the plurality of second signal lines and the plurality of second scanning lines;

[0021] A plurality of second switch elements, disposed in the plurality of second pixels; and

[0022] The third orientation film,

[0023] The fourth substrate includes a fourth alignment film facing the third alignment film.

[0024] The first display panel and the second display panel are arranged in contact with each other.

[0025] The first polymer dispersed liquid crystal layer is disposed between the first alignment film and the second alignment film.

[0026] The second polymer dispersed liquid crystal layer is disposed between the third alignment film and the fourth alignment film.

[0027] The distance between the first alignment film and the second alignment film is set to a first thickness,

[0028] The distance between the third alignment film and the fourth alignment film is set to a second thickness,

[0029] The first thickness and the second thickness are each less than 2 μm.

[0030] Technical Effects

[0031] According to the display device of this embodiment, it is possible to reduce the voltage of the polymer dispersed liquid crystal layer and suppress a decrease in scattering brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an exploded perspective view schematically showing the structure of a display device including two display panels.

[0033] Figure 2 This is a cross-sectional view showing an example of a schematic configuration of a display device.

[0034] Figure 3 This is a cross-sectional view showing an example of a schematic configuration of a display device.

[0035] Figure 4 This is a cross-sectional view showing an example of a schematic configuration of a display device.

[0036] Figure 5 This is a cross-sectional view showing an example of a schematic configuration of a display device.

[0037] Figure 6 It is a plan view showing the structure of pixels in a substrate.

[0038] Figure 7 Yes means Figure 6 An enlarged top view of an example of a switching element is shown.

[0039] Figure 8 It is along Figure 7 A cross-sectional view of the display panel taken along line A1 - A2 is shown.

[0040] Fig. 9 This is a diagram showing the relationship between the applied voltage and the scattering brightness with respect to the thickness of the liquid crystal layer.

[0041] Fig.10 Is Fig. 9 An enlarged view of the area surrounded by the dotted line is shown.

[0042] Fig.11 This is a diagram showing the relationship between the threshold voltage and the thickness of the liquid crystal layer. DETAILED DESCRIPTION

[0043] Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the disclosure is only an example, and appropriate changes that can be easily thought of by those skilled in the art while maintaining the main purpose of the utility model are of course included in the scope of the present invention. In addition, in order to make the description clearer, the drawings schematically show the width, thickness, shape, etc. of each part compared with the actual method, but this is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each figure, the same figure mark is sometimes used for the same elements as those described in the drawings that have appeared, and the detailed description is appropriately omitted.

[0044] The embodiments described in this specification are not general cases, but are embodiments for illustrating the same or corresponding special technical features of the present utility model. Figure 1 A display device according to one embodiment will be described in detail.

[0045] In the present embodiment, the first direction X, the second direction Y, and the third direction Z are orthogonal to each other, but may intersect at an angle other than 90 degrees. The direction of the front end of the arrow pointing to the third direction Z is defined as up or above, and the direction on the side opposite to the direction of the front end of the arrow pointing to the third direction Z is defined as down or below. In addition, the first direction X, the second direction Y, and the third direction Z are sometimes referred to as the X direction, the Y direction, and the Z direction, respectively.

[0046] In addition, in the case of "a second component above the first component" and "a second component below the first component", the second component may be in contact with the first component, or may be located away from the first component. In the latter case, a third component may be interposed between the first component and the second component. On the other hand, in the case of "a second component above the first component" and "a second component below the first component", the second component is in contact with the first component.

[0047] In addition, assuming that there is an observation position for observing the display device on the front end side of the arrow of the third direction Z, observation from the observation position toward the X-Y plane defined by the first direction X and the second direction Y is referred to as a top view. Observing the cross section of the display device on the X-Z plane defined by the first direction X and the third direction Z, or on the Y-Z plane defined by the second direction Y and the third direction Z is referred to as a cross-sectional view.

[0048] [Implementation Method]

[0049] Figure 1 This is an exploded perspective view schematically showing the structure of a display device including two display panels. Figure 1 A three-dimensional space defined by a first direction X, a second direction Y perpendicular to the first direction X, and a third direction Z perpendicular to the first direction X and the second direction Y is shown.

[0050] like Figure 1 As shown, the display device DSP includes a first display panel PNL1 and a second display panel PNL2.

[0051] The first display panel PNL1 is rectangular in one example. In the illustrated example, the short side EX of the first display panel PNL1 is parallel to the first direction X, and the long side EY of the first display panel PNL1 is parallel to the second direction Y. The third direction Z corresponds to the thickness direction of the first display panel PNL1. The main surface of the first display panel PNL1 is parallel to the X-Y plane defined by the first direction X and the second direction Y. The first display panel PNL1 has an active area AA1 (display area) and a non-display area NDA1 located outside the active area AA1. The non-display area NDA1 has a terminal area MT1 for mounting a driver IC and a flexible wiring substrate. Figure 1 In FIG. 1 , the terminal region MT1 is indicated by oblique lines.

[0052] The active area AA1 is an area for displaying an image, and includes, for example, a plurality of pixels PX1 arranged in a matrix along the first direction X and the second direction Y. Figure 1 As shown in an enlarged manner in FIG. 8 , each pixel PX1 is arranged in a region partitioned by the scanning line GL and the signal line SL, and includes a switching element SW, a pixel electrode PE, a common electrode CE, a liquid crystal layer LC, and the like.

[0053] The switch element SW is, for example, composed of a thin film transistor (TFT), and is electrically connected to the scan line GL and the signal line SL. The scan line GL is electrically connected to the switch element SW in each pixel PX1 arranged along the first direction X. The signal line SL is electrically connected to the switch element SW in each pixel PX1 arranged along the second direction Y. The pixel electrode PE is electrically connected to the switch element SW. The pixel electrode PE is respectively opposite to the common electrode CE, and the liquid crystal layer LC is driven by the electric field generated between the pixel electrode PE and the common electrode CE. The capacitor CS is, for example, formed between an electrode having the same potential as the common electrode CE and an electrode having the same potential as the pixel electrode PE.

[0054] The liquid crystal layer LC has a polymer dispersed liquid crystal (PDLC) including a polymer and liquid crystal molecules. In one example, the polymer is a liquid crystal polymer. The polymer is formed into stripes extending in one direction. The liquid crystal molecules are dispersed in the gaps between the polymers and are oriented in such a way that their major axes extend along the direction in which the stripes extend. The polymer and the liquid crystal molecules have optical anisotropy or refractive index anisotropy, respectively. The responsiveness of the polymer to an electric field is lower than that of the liquid crystal molecules to an electric field.

[0055] In one example, the orientation direction of the polymer remains almost unchanged regardless of the presence or absence of an electric field. On the other hand, the orientation direction of the liquid crystal molecules changes according to the electric field when a voltage 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 and the liquid crystal molecules are parallel to each other, and the light incident on the liquid crystal layer LC passes through the liquid crystal layer LC with almost no scattering (transparent state). When a voltage is applied to the liquid crystal layer LC, the optical axes of the polymer and the liquid crystal molecules cross each other, and the light incident on the liquid crystal layer LC is scattered in the liquid crystal layer LC (scattering state).

[0056] The terminal region MT1 extends along the short side EX of the first display panel PNL1. A terminal portion is formed in the terminal region MT1, and the first display panel PNL1 is electrically connected to an external device such as a flexible wiring substrate via the terminal portion.

[0057] The second display panel PNL2 has a structure substantially the same as that of the first display panel PNL1. The second display panel PNL2 has a plurality of pixels PX2 arranged in a matrix along the first direction X and the second direction Y in the effective area AA2 (display area). The structure of the pixel PX2 is the same as that of the pixel PX1, so the detailed description is cited above and omitted. In the present embodiment, the pixel PX1 and the pixel PX2 have the same structure and the same size. More specifically, the pixel PX1 and the pixel PX2 have the same layer structure. In addition, the lengths of the first direction X and the second direction Y of the pixel PX1 and the pixel PX2 are the same.

[0058] In the second display panel PNL2, the liquid crystal layer also includes a polymer dispersed liquid crystal (PDLC) including a polymer and liquid crystal molecules. In addition, although not shown in the figure, the liquid crystal layer of the second display panel PNL2 is also referred to as the liquid crystal layer LC2. In this case, the liquid crystal layer LC of the first display panel PNL1 is also referred to as the liquid crystal layer LC1. In the case where the liquid crystal layer LC1 and the liquid crystal layer LC2 are not distinguished, they are simply referred to as the liquid crystal layer LC.

[0059] The second display panel PNL2 is the same as the first display panel PNL1, and has a non-display area NDA2 located outside the effective area AA2. The non-display area NDA2 has a terminal area MT2 for mounting a driver IC and a flexible wiring substrate. The non-display area NDA2 and the terminal area MT2 are the same as the non-display area NDA1 and the terminal area MT1, respectively. The flexible wiring substrates of the first display panel PNL1 and the second display panel PNL2 are electrically connected and connected to a control element. The pixels PX1 and the pixels PX2 are synchronously driven by a signal from the control element. The same image signal is input to the pixels PX1 and the pixels PX2 that overlap when viewed from above.

[0060] The threshold voltage of the polymer dispersed liquid crystal layer is higher than that of the TN (Twisted Nematic) liquid crystal layer, for example. Therefore, the polymer dispersed liquid crystal layer needs to be driven with a higher voltage. In order to drive the polymer dispersed liquid crystal layer, a high withstand voltage driver is required.

[0061] The threshold voltage of the polymer dispersed liquid crystal layer is proportional to the electric field strength. By reducing the thickness of the polymer dispersed liquid crystal layer, it is possible to achieve a lower voltage. As long as the polymer dispersed liquid crystal layer can achieve a lower voltage, it is not necessary to use a high withstand voltage driver.

[0062] However, if the thickness of the polymer-dispersed liquid crystal layer is reduced, there is a concern that the scattering brightness when a voltage is applied will decrease.

[0063] Therefore, if Figure 1As shown, by stacking two display panels having a thin polymer dispersed liquid crystal layer, the voltage of the polymer dispersed liquid crystal layer can be reduced and a decrease in scattered brightness can be suppressed.

[0064] Figure 2 The display device DSP includes a first display panel PNL1, a second display panel PNL2, a light guide plate LG1, a light guide plate LG2, a light source LS1, and a light source LS2.

[0065] The first display panel PNL1 emits display light DT1 upward. The second display panel PNL2 emits display light DT2 upward. It is assumed that an observer observes the display device DSP from the upper direction of the display device DSP in a direction opposite to the third direction Z. The display light DT1 and the display light DT2 reach the observer's eye EYE, so that the observer can visually confirm the display image displayed by the display device DSP.

[0066] The first display panel PNL1 includes a substrate SUB11, a substrate SUB21, and a liquid crystal layer (the aforementioned liquid crystal layer LC1 (not shown)) provided between the substrates SUB11 and SUB21. The substrates SUB11 and SUB21 are sequentially stacked along the third direction Z.

[0067] A light guide plate LG1 is provided on the substrate SUB21. The material of the light guide plate LG1 is, for example, glass. Light from the light source LS1 propagates through the light guide plate LG1, the substrate SUB11, and the substrate SUB21. The light guide plate LG1 preferably has the same refractive index as the substrate SUB11 and the substrate SUB21.

[0068] A light source LS1 is provided at an end of the first display panel PNL1. More specifically, the light source LS1 is provided opposite to an end of the light guide plate LG1. The light source LS1 includes, for example, a light source element that emits red, a light source element that emits green, and a light source element that emits blue. The light source element is, for example, a light emitting diode (LED).

[0069] The second display panel PNL2 is arranged at a position symmetrical to the first display panel PNL1 with respect to the XY plane and the YZ plane. In other words, the second display panel PNL2 is arranged at a position opposite to the first display panel PNL1 in vertical direction with respect to the XY plane and opposite to the first display panel PNL1 in horizontal direction with respect to the YZ plane.

[0070] The second display panel PNL2 includes a substrate SUB12, a substrate SUB22, and a liquid crystal layer (the aforementioned liquid crystal layer LC2 (not shown)) provided between the substrate SUB12 and the substrate SUB22. The substrate SUB22 and the substrate SUB12 are sequentially stacked along the third direction Z.

[0071] A light guide plate LG2 is provided below and in contact with the substrate SUB22. The material of the light guide plate LG2 is the same as that of the light guide plate LG1, for example, glass. Light from the light source LS2 propagates through the light guide plate LG2, the substrate SUB12, and the substrate SUB22. The light guide plate LG2 preferably has the same refractive index as the substrate SUB12 and the substrate SUB22.

[0072] The substrate SUB11 of the first display panel PNL1 and the substrate SUB12 of the second display panel PNL2 are connected to each other. The surface of the substrate SUB11 and the substrate SUB12 on which the switch element SW is provided is the upper surface, and the surface opposite to the main surface is the lower surface. The lower surfaces of the substrate SUB11 and the substrate SUB12 are connected to each other.

[0073] A light source LS2 is provided at the end of the second display panel PNL2. More specifically, the light source LS2 is provided opposite to the end of the light guide plate LG2. The light source LS2 is the same as the light source LS1, and has, for example, a light source element that emits red, a light source element that emits green, and a light source element that emits blue. The light source element is, for example, a light emitting diode.

[0074] The light source LS2 is arranged at a position that is line-symmetrical to the light source LS1 with respect to the X-Y plane and the Y-Z plane, respectively. In other words, the light source LS2 is arranged at a position that is vertically opposite to the light source LS1 with respect to the X-Y plane and horizontally opposite to the light source LS1 with respect to the Y-Z plane. That is, the direction in which the light from the light source LS1 is incident on the light guide plate LG1 (the direction opposite to the first direction X) and the direction in which the light from the light source LS2 is incident on the light guide plate LG2 (the first direction) are opposite to each other. In other words, the direction in which the light from the light source LS1 is incident on the first display panel PNL1 (the direction opposite to the first direction X) and the direction in which the light from the light source LS2 is incident on the second display panel PNL2 (the first direction) are opposite to each other.

[0075] After the light from the light source LS1 enters the light guide plate LG1, it propagates inside the first display panel PNL1 through the light guide plate LG1, substrates SUB11 and SUB21. In addition, the light from the light source LS1 propagates inside the second display panel PNL2 through substrates SUB22, substrate SUB12 and the light guide plate LG2.

[0076] After the light from the light source LS2 enters the light guide plate LG2, it propagates inside the second display panel PNL2 through the light guide plate LG2, substrate SUB12 and substrate SUB22. In addition, the light from the light source LS2 propagates inside the first display panel PNL1 through substrates SUB21, substrate SUB11 and light guide plate LG1.

[0077] Figure 3 1 is a cross-sectional view showing an example of a schematic configuration of a display device. The display device DSP includes a first display panel PNL1, a second display panel PNL2, a light guide plate LG1, a light guide plate LG2, and a light source LS1. Figure 3 In the configuration example shown, Figure 2 The configuration example shown is different in that the light source LS2 is not provided.

[0078] exist Figure 3 The display device DSP shown is also connected with Figure 2 Similarly, the first display panel PNL1 emits display light DT1 upward. The second display panel PNL2 emits display light DT2 upward. It is assumed that an observer observes the display device DSP from above the display device DSP in a direction opposite to the third direction Z. The display light DT1 and the display light DT2 reach the observer's eye EYE, so that the observer can visually confirm the display image displayed by the display device DSP.

[0079] exist Figure 3 In the display device DSP shown, no light source is provided in the second display panel PNL2. However, light emitted from the light source LS1 provided in the first display panel PNL1 propagates inside the substrate SUB12, the substrate SUB22 and the light guide plate LG2 of the second display panel PNL2. Thus, the second display panel PNL2 can display.

[0080] Figure 4 1 is a cross-sectional view showing an example of a schematic configuration of a display device. The display device DSP includes a first display panel PNL1, a second display panel PNL2, a light guide plate LG1, a light guide plate LG2, a light source LS1, and a light source LS2. Figure 4 The configuration example shown is Figure 2 The difference from the illustrated configuration example is that the components of the first display panel PNL1 and the second display panel PNL2 are arranged at the same positions with respect to the XY plane and the YZ plane, respectively.

[0081] exist Figure 4 The display device DSP shown is also connected with Figure 2Similarly, the first display panel PNL1 emits display light DT1 upward. The second display panel PNL2 emits display light DT2 upward. It is assumed that an observer observes the display device DSP from above the display device DSP in a direction opposite to the third direction Z. The display light DT1 and the display light DT2 reach the observer's eye EYE, so that the observer can visually confirm the display image displayed by the display device DSP.

[0082] exist Figure 4 In the display device DSP shown in FIG. 1 , the first display panel PNL1 and Figure 2 same.

[0083] In the second display panel PNL2, the substrate SUB12 and the substrate SUB22 are sequentially stacked along the third direction Z. A light guide plate LG2 is provided on the substrate SUB22. A light source LS2 is provided at an end of the light guide plate LG2. The light source LS2 is opposite to the light source LS1 along the third direction Z.

[0084] Figure 4 The second display panel PNL2 shown has the same configuration as the first display panel PNL1. That is, as described above, the components of the first display panel PNL1 and the second display panel PNL2 are arranged at the same positions with respect to the XY plane and the YZ plane, respectively.

[0085] The light guide plate LG2 disposed on the second display panel PNL2 is disposed in contact with the first display panel PNL1. More specifically, the light guide plate LG2 is disposed in contact with the substrate SUB11.

[0086] exist Figure 4 In the embodiment, the direction in which the light from the light source LS1 is incident on the light guide plate LG1 (the direction opposite to the first direction X) is the same as the direction in which the light from the light source LS2 is incident on the light guide plate LG2 (the direction opposite to the first direction X).

[0087] Figure 5 1 is a cross-sectional view showing an example of a schematic configuration of a display device. The display device DSP includes a first display panel PNL1, a second display panel PNL2, a light guide plate LG1, a light guide plate LG2, and a light source LS1. Figure 5 The configuration example shown is Figure 4 Compared with the illustrated configuration example, it is different in that the light source LS2 is not provided.

[0088] exist Figure 5 The display device DSP shown is also connected with Figure 2Similarly, the first display panel PNL1 emits display light DT1 upward. The second display panel PNL2 emits display light DT2 upward. It is assumed that an observer observes the display device DSP from above the display device DSP in a direction opposite to the third direction Z. The display light DT1 and the display light DT2 reach the observer's eye EYE, so that the observer can visually confirm the display image displayed by the display device DSP.

[0089] exist Figure 5 In the display device DSP shown in FIG. 1 , no light source is provided in the second display panel PNL2. Figure 3 The display device DSP shown is the same as Figure 5 In the display device DSP shown, light emitted from the light source LS1 provided in the first display panel PNL1 also propagates inside the substrate SUB12, substrate SUB22 and light guide plate LG2 of the second display panel PNL2, thereby enabling display on the second display panel PNL2.

[0090] Figure 6 1 is a plan view showing the structure of a pixel PX1 in a substrate SUB11. The substrate SUB11 includes a scanning line GL, a signal line SL, a switching element SW, an organic insulating layer OI, a metal wiring ML, a capacitor electrode CSE, and a pixel electrode PE.

[0091] In addition, Figure 6 Only the pixel PX1 is shown in FIG. 1 , but the second display panel PNL2 also includes a pixel (pixel PX2 ) having the same structure as the pixel PX1 . The substrate SUB12 has the same structure as the substrate SUB11 .

[0092] The two scanning lines GL extend in the first direction X and are arranged at intervals in the second direction Y. The two signal lines SL extend in the second direction Y and are arranged at intervals in the first direction X. The pixel PX1 corresponds to a region partitioned by the two signal lines SL and the two scanning lines GL.

[0093] The switch element SW is arranged at the intersection of the scanning line GL and the signal line SL. The specific structure of the switch element SW will be described later. The switch element SW may also be a bottom gate type in which the gate electrode is located below the semiconductor layer. The switch element SW may also be a top gate type in which the gate electrode is located above the semiconductor layer. The semiconductor layer is formed of amorphous silicon, for example, but may also be formed of polycrystalline silicon or an oxide semiconductor.

[0094] The organic insulating layer OI is patterned. Figure 6 In other words, the organic insulating layer OI overlaps the scanning line GL, the signal line SL, and the switching element SW.

[0095] The organic insulating layer OI includes a first portion OX overlapping the scanning line GL and a second portion OY overlapping the signal line SL. The first portion OX includes a first side surface E1 and a second side surface E2 opposite to the first side surface E1. The first side surface E1 and the second side surface E2 extend along the first direction X. The second portion OY includes a third side surface E3 and a fourth side surface E4 opposite to the third side surface E3.

[0096] In addition, in this embodiment, the area where the organic insulating layer OI is configured is the first area PA1 of the substrate SUB11, and the area where the organic insulating layer OI is not configured is the second area PA2 of the substrate SUB11. The second area PA2 is located inside the area surrounded by the first area PA1. The second area PA2 is located inside the area surrounded by the two signal lines SL and the two scanning lines GL.

[0097] The metal wiring ML is arranged in the first area PA1. Figure 6 In the plan view, the metal wiring ML is formed in a lattice shape. That is, the metal wiring ML overlaps the scanning line GL, the signal line SL and the switching element SW. The metal wiring ML includes a first wiring portion MX overlapping the scanning line GL and the first portion OX and a second wiring portion MY overlapping the signal line SL and the second portion OY.

[0098] As indicated by the single-dot chain line, the capacitor electrode CSE is arranged over the plurality of pixels PX1 and is arranged over substantially the entire area of ​​the substrate SUB11. That is, the capacitor electrode CSE is arranged in the first area PA1 and the second area PA2. The capacitor electrode CSE overlaps the switch element SW, the scanning line GL, the signal line SL, and the organic insulating layer OI in the first area PA1.

[0099] In addition, the capacitor electrode CSE may also be formed in a lattice shape similar to the metal wiring ML. The lattice-shaped capacitor electrode CSE covers the scanning line GL, the signal line SL, the switch element SW, and the side E (the first side E1, the second side E2, the third side E3, and the fourth side E4) of the organic insulating layer OI. That is, the lattice-shaped capacitor electrode CSE has an opening at the position of the second area PA2.

[0100] The pixel electrode PE is provided in substantially the entire area of ​​the second area PA2. Figure 6 In the example shown, the pixel electrode PE is provided inside the region where the organic insulating layer OI is provided, and overlaps with the capacitor electrode CSE in the second region PA2. Alternatively, the pixel electrode PE may overlap the first portion OX and the second portion OY.

[0101] exist Figure 6 In the illustrated example, the spacer SP overlaps the switching element SW, and a predetermined gap is formed between the substrate SUB11 and the substrate SUB21 .

[0102] Figure 7 Yes means Figure 6 1 is an enlarged top view of an example of a switching element shown. The switching element SW includes a semiconductor layer SC, a gate electrode GE, a source electrode SE, and a drain electrode DE. The gate electrode GE is formed integrally with the scanning line GL. The semiconductor layer SC overlaps with the gate electrode GE. The two source electrodes SE are formed integrally with the signal line SL and are respectively connected to the semiconductor layer SC. The drain electrode DE is located between the two source electrodes SE and is connected to the semiconductor layer SC. The drain electrode DE has a connecting portion DEA. The connecting portion DEA is electrically connected to the pixel electrode PE via the opening CA formed in the capacitor electrode CSE and the contact hole CH.

[0103] Figure 8 It is along Figure 7 The cross-sectional view of the line A1-A2 of the display panel shown. The substrate SUB11 also includes a substrate BA1, an insulating layer GI, an insulating layer PAS, an insulating layer DIE, and an alignment film AL1. The substrate BA1 includes a main surface (lower surface) BS1a and a main surface (upper surface) BS1b on the opposite side of the main surface BS1a. The main surface BS1a and the main surface BS1b are surfaces substantially parallel to the X-Y plane. The main surface (lower surface) BS1a and the main surface (upper surface) BS1b of the substrate BA1 correspond to the lower surface and the upper surface of the substrate SUB11. Similarly, the main surface (lower surface) BS1a and the main surface (upper surface) BS1b of the substrate BA1 correspond to the lower surface and the upper surface of the substrate SUB12.

[0104] The gate electrode GE integrated with the scanning line GL is arranged on the main surface BS1b side. The insulating layer GI covers the gate electrode GE and the scanning line GL and is in contact with the main surface BS1b. The semiconductor layer SC is located on the insulating layer GI just above the gate electrode GE.

[0105] The two source electrodes SE integral with the signal line SL are respectively connected to the semiconductor layer SC, and a part of them is located on the insulating layer GI. The drain electrode DE is connected to the semiconductor layer SC. The insulating layer PAS covers the semiconductor layer SC, the source electrode SE and the drain electrode DE constituting the switching element SW, and covers the insulating layer GI.

[0106] The first portion OX of the organic insulating layer OI is in contact with the upper surface PS2 of the insulating layer PAS just above the gate electrode GE and the scanning line GL, or just above the switching element SW. The first wiring portion MX of the metal wiring ML is located above the first portion OX just above the gate electrode GE and the scanning line GL, or just above the switching element SW.

[0107] The capacitor electrode CSE covers the first wiring portion MX and the first portion OX in the first area PA1. That is, the first side surface E1 and the second side surface E2 of the first portion OX are covered by the capacitor electrode CSE. The first wiring portion MX is connected to the capacitor electrode CSE and is electrically connected to each other. In addition, the capacitor electrode CSE is connected to the upper surface PS2 of the insulating layer PAS in the second area PA2.

[0108] The insulating layer DIE is disposed in the first area PA1 and the second area PA2, covering the capacitor electrode CSE. The pixel electrode PE is located on the insulating layer DIE in the second area PA2. The pixel electrode PE and the capacitor electrode CSE are opposite to each other through the insulating layer DIE, forming an accumulation capacitor required for image display in the pixel PX1.

[0109] The switch element SW is located between the pixel electrodes PE adjacent to each other along the second direction Y. The first side surface E1 and the second side surface E2 are respectively located between the switch element SW and the pixel electrode PE along the second direction Y. The alignment film AL1 covers the pixel electrode PE and the insulating layer DIE.

[0110] The substrate SUB21 includes a base material BA2, a light shielding layer BM, a common electrode CE, a spacer SP, and an alignment film AL2. The base material BA2 includes a main surface (lower surface) BS2a and a main surface (upper surface) BS2b on the side opposite to the main surface BS2a. The main surface BS2a and the main surface BS2b are surfaces substantially parallel to the XY plane. The main surface BS2a and the main surface BS2b face each other.

[0111] The light shielding layer BM and the common electrode CE are arranged on the main surface BS2 a . The light shielding layer BM is located directly above the first side surface E1 and the second side surface E2 of the first portion OX, directly above the switching element SW, and directly above the gate electrode GE.

[0112] The common electrode CE is arranged throughout the plurality of pixels PX and covers the light shielding layer BM. The common electrode CE is electrically connected to the capacitor electrode CSE and has the same potential as the capacitor electrode CSE. The spacer SP is provided under the common electrode CE and is in contact with the alignment film AL1. The spacer SP is located between the organic insulating layer OI and the light shielding layer BM. The alignment film AL2 covers the common electrode CE.

[0113] The liquid crystal layer LC1 (liquid crystal layer LC) is located between the substrate SUB11 and the substrate SUB21 and is in contact with the alignment film AL1 and the alignment film AL2, respectively.

[0114] The base material BA1 and the base material BA2 are light-transmitting insulating base materials, and examples of such base materials include glass and plastic.

[0115] The insulating layer GI, the insulating layer PAS, and the insulating layer DIE are formed of transparent inorganic insulating materials such as silicon nitride and silicon oxide. The insulating layer DIE is preferably an inorganic insulating material with a high dielectric constant. The organic insulating layer OI is formed of transparent organic insulating materials such as acrylic resin.

[0116] The scanning line GL, the signal line SL, and the metal wiring ML are, for example, a laminated body in which a plurality of conductive layers are stacked. Such a laminated body may be, for example, a laminated body in which a conductive layer containing molybdenum (Mo), a conductive layer containing aluminum (Al), and a conductive layer containing molybdenum (Mo) are stacked in sequence. However, the laminated body is not limited thereto. The laminated body may also be a laminated body in which a conductive layer containing titanium (Ti), a conductive layer containing aluminum (Al), and a conductive layer containing titanium (Ti) are stacked in sequence.

[0117] In addition, the scanning line GL may be a laminate of a conductive layer containing molybdenum (Mo) and a conductive layer containing aluminum (Al), and preferably, the conductive layer containing aluminum (Al) is in contact with the main surface BS1b. Aluminum (Al) has a higher light reflectivity than molybdenum (Mo). Compared with the case where the conductive layer containing molybdenum (Mo) of the scanning line GL is in contact with the main surface BS1b, it is possible to suppress the light propagating in the substrate BA1 from being absorbed by the scanning line GL.

[0118] The capacitor 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).

[0119] The light shielding layer BM is, for example, a conductive layer having a lower resistance than the common electrode CE, and is formed of an opaque metal material such as molybdenum, aluminum, tungsten, titanium, or silver.

[0120] The common electrode CE is in contact with the light shielding layer BM and is thus electrically connected to the light shielding layer BM. Thus, the common electrode CE has a low resistance.

[0121] 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 subjected to an alignment treatment along the first direction X. The alignment treatment may be a rubbing treatment or a photo-alignment treatment.

[0122] The thickness of the liquid crystal layer LC is set to thickness CG. The thickness CG corresponds to the length from the alignment film AL1 to the alignment film AL2 in the second area PA2 along the third direction Z. In other words, the thickness CG corresponds to the length between the alignment film AL1 and the alignment film AL2 in the area where the switching element SW and the light shielding layer BM are not provided. The thickness CG is preferably less than 2 μm. If the thickness CG is thicker than 2 μm, the threshold voltage of the display panel increases.

[0123] However, if the thickness CG of the liquid crystal layer LC of the display panel is reduced, the scattering brightness decreases. Therefore, as described above, by stacking two display panels, the voltage of the polymer dispersed liquid crystal layer is reduced and the reduction of the scattering brightness is suppressed.

[0124] Fig. 9 This is a diagram showing the relationship between the applied voltage and the scattering brightness with respect to the thickness of the liquid crystal layer. Fig.10 Is Fig. 9 The enlarged view of the area surrounded by the dotted line is shown. In other words, Fig.10 yes Fig. 9 The horizontal axis and the vertical axis are enlarged near 0. Fig. 9 as well as Fig.10 The horizontal axis is the voltage V applied to the liquid crystal layer LC. Fig. 9 as well as Fig.10 The vertical axis is the scattering brightness of the liquid crystal layer LC. The thickness CG of the liquid crystal layer LC is set to 3 μm, 2.5 μm, 2 μm, 1.5 μm and 1.0 μm, which are represented by a thick dashed line, a double-dashed line, a solid line, a single-dashed line and a thin dashed line, respectively.

[0125] For example Fig. 9 As shown in FIG. 1 , if the thickness CG is small, the scattering intensity LM is small even if the same voltage V is applied. In other words, if the thickness CG is large, the scattering intensity LM is large even if the same voltage V is applied.

[0126] Fig.11 This is a diagram showing the relationship between the threshold voltage and the thickness of the liquid crystal layer. Fig.11 The horizontal axis is the thickness CG of the liquid crystal layer LC. Fig.11 The vertical axis is the threshold voltage Vth of the liquid crystal layer LC. Fig.11 As shown, as the thickness CG becomes smaller, the threshold voltage Vth becomes smaller.

[0127] According to the above, by reducing the thickness CG, a display panel with a small threshold voltage Vth can be obtained (see Fig.11 By overlapping two display panels 2, a display device DSP having an effect of increasing the thickness CG can be obtained. In the display device DSP, the same effect as that of a display panel with a larger thickness CG can be obtained, so the scattering intensity LM becomes larger (refer to Fig. 9 as well as Fig.10 ). Thus, according to the present disclosure, it is possible to obtain a display device DSP that can achieve low-voltage driving and increase in scattering brightness.

[0128] In the present disclosure, substrate SUB11, substrate SUB21, substrate SUB12 and substrate SUB22 are also referred to as the first substrate, the second substrate, the third substrate and the fourth substrate, respectively. Liquid crystal layer LC1 and liquid crystal layer LC2 are also referred to as the first polymer dispersed liquid crystal layer and the second polymer dispersed liquid crystal layer, respectively. Light source LS1 and light source LS2 are also referred to as the first light source and the second light source, respectively.

[0129] In the present disclosure, the pixel PX1 and the pixel PX2 are also referred to as the first pixel and the second pixel, respectively. The first area PA1 and the second area PA2 of the first display panel PNL1 are also referred to as the first area and the second area, respectively. The first area PA1 and the second area PA2 of the second display panel PNL2 are also referred to as the third area and the fourth area, respectively.

[0130] In the present disclosure, the alignment film AL1 and the alignment film AL2 of the first display panel PNL1 are also referred to as the first alignment film and the second alignment film, respectively. The alignment film AL1 and the alignment film AL2 of the second display panel PNL2 are also referred to as the third alignment film and the fourth alignment film, respectively. The organic insulating layer OI of the first display panel PNL1 is also referred to as the first organic insulating layer, and the organic insulating layer OI of the second display panel PNL2 is also referred to as the second organic insulating layer.

[0131] In the present disclosure, the thickness CG of the first display panel PNL1 is also referred to as the first thickness, and the thickness CG of the second display panel PNL2 is also referred to as the second thickness. In addition, in the present disclosure, the components of the first display panel PNL1 are sometimes labeled with "first" and the components of the second display panel PNL2 are sometimes labeled with "second".

[0132] Although several embodiments of the utility model are described, these embodiments are presented as examples and are not intended to limit the scope of the utility model. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the utility model. These embodiments and their variations are included in the scope and purpose of the utility model, and are included in the scope of the utility model and its equivalents recorded in the claims.

Claims

1. A display device, characterized in that: have: A first display panel comprises a first substrate, a second substrate, and a first polymer dispersed liquid crystal layer disposed between the first substrate and the second substrate; A second display panel comprises a third substrate, a fourth substrate, and a second polymer dispersed liquid crystal layer disposed between the third substrate and the fourth substrate; as well as a first light source, disposed at an end of the first display panel, The first substrate comprises: a plurality of first signal lines; a plurality of first scanning lines; a plurality of first pixels, divided by the plurality of first signal lines and the plurality of first scan lines; A plurality of first switch elements, disposed in the plurality of first pixels; as well as The first orientation film, The second substrate includes a second alignment film facing the first alignment film. The third substrate comprises: a plurality of second signal lines; a plurality of second scanning lines; a plurality of second pixels, divided by the plurality of second signal lines and the plurality of second scanning lines; A plurality of second switch elements, disposed in the plurality of second pixels; as well as The third orientation film, The fourth substrate includes a fourth alignment film facing the third alignment film. The first display panel and the second display panel are arranged in contact with each other. The first polymer dispersed liquid crystal layer is disposed between the first alignment film and the second alignment film. The second polymer dispersed liquid crystal layer is disposed between the third alignment film and the fourth alignment film. The distance between the first alignment film and the second alignment film is set to a first thickness, The distance between the third alignment film and the fourth alignment film is set to a second thickness, The first thickness and the second thickness are each less than 2 μm.

2. The display device according to claim 1, characterized in that A first light guide plate is provided in contact with the second substrate. A second light guide plate is provided in contact with the fourth substrate.

3. The display device according to claim 2, characterized in that: further comprising a second light source disposed at an end of the second display panel, The first light source is arranged opposite to an end of the first light guide plate, The second light source is arranged opposite to an end of the second light guide plate, The light from the first light source is incident on the end of the first light guide plate. The light from the second light source is incident on an end portion of the second light guide plate.

4. The display device according to claim 3, characterized in that A direction in which the light from the first light source is incident on the first display panel and a direction in which the light from the second light source is incident on the second display panel are opposite to each other.

5. The display device according to claim 3, characterized in that: The direction in which the light from the first light source is incident on the first display panel is the same as the direction in which the light from the second light source is incident on the second display panel.

6. The display device according to claim 1, characterized in that: The first substrate and the third substrate are disposed in contact with each other.

7. The display device according to claim 2, characterized in that: The first light guide plate and the third substrate are disposed in contact with each other.

8. The display device according to claim 1, characterized in that: The first substrate includes a first organic insulating layer overlapping the first switching element. The third substrate includes a second organic insulating layer overlapping the second switching element. The plurality of first pixels include: a first region in which the first organic insulating layer is provided in a manner overlapping the plurality of first signal lines and the plurality of first scanning lines; and a second region where the first organic insulating layer is not provided inside the plurality of first pixels, The plurality of second pixels include: a third region in which the second organic insulating layer is provided in a manner overlapping the plurality of second signal lines and the plurality of second scanning lines; and a fourth region in which the second organic insulating layer is not provided inside the plurality of second pixels. The first thickness is the thickness of the first polymer dispersed liquid crystal layer in the second region, The second thickness is the thickness of the second polymer-dispersed liquid crystal layer in the fourth region.

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