Electronic device

Abstract

Provided is an electronic device having a transmissive display panel and a reflective display panel, and improved display quality of the reflective display panel. An electronic device (300) includes: a first display panel (100) having a first display surface; a second display panel (200) having a second display surface, and configured to have light emitted from the first display surface incident to the second display surface, the first display panel configured to have light emitted from the first display surface and incident to the second display surface containing a large P-polarized light component, the second display panel being a reflective display panel, and having a polarizing plate at the second display surface, the polarizing plate configured to absorb an S-polarized light component of the incident light.

Description

Technical Field

[0001] This invention relates to electronic devices having two display panels. Examples of such electronic devices include foldable display devices and notebook computers. Background Technology

[0002] Previously, electronic devices with two display panels were known. For example, Patent Document 1 discloses a liquid crystal display system comprising a reflective liquid crystal display panel, a transmissive liquid crystal display panel, and a computer. This liquid crystal display system is, for example, a notebook computer, in which the reflective liquid crystal display panel is positioned as the main display on the front, and the transmissive liquid crystal display panel is positioned on the hand-side for pen input, etc. Furthermore, Patent Document 2 discloses a configuration in which the transmissive liquid crystal display panel is positioned on the front, the reflective liquid crystal display panel is positioned on the hand-side as an input interface, and the light source used for the backlight of the transmissive liquid crystal panel is also used as the front light source of the reflective liquid crystal panel.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 7-294892

[0006] Patent Document 2: Japanese Patent Application Publication No. 2006-53678 Summary of the Invention

[0007] The technical problem to be solved by the present invention

[0008] The electronic devices described in Patent Documents 1 and 2 achieve low power consumption by using a reflective liquid crystal display panel. Patent Document 2 discloses a configuration that efficiently utilizes the illumination light source of the liquid crystal display panel, but leaves room for improving the display quality of the reflective liquid crystal display panel.

[0009] The purpose of this invention is to improve the display quality of a reflective display panel in an electronic device having a display panel as a main display and a reflective display panel.

[0010] Technical solutions for solving technical problems

[0011] According to embodiments of the present invention, solutions described in the following items are provided.

[0012] [Project 1] An electronic device includes: a first display panel having a first display surface; a second display panel having a second display surface and configured such that light emitted from the first display surface is incident on the second display surface, the first display panel being configured such that light emitted from the first display surface and incident on the second display surface contains a majority of P-polarized light components, the second display panel being a reflective display panel having a polarizing plate on the second display surface, the polarizing plate being configured to absorb the S-polarized light components of the incident light.

[0013] [Item 2] In the electronic device described in Item 1, the first display panel has an organic EL element layer and a circular polarizer, the circular polarizer being disposed on the first display surface side of the organic EL element layer.

[0014] [Item 3] In the electronic device described in Item 1, the first display panel is a transmissive display panel having: a liquid crystal element layer; a first polarizing plate having an absorption axis parallel to the horizontal direction of the first display surface; a second polarizing plate having an absorption axis in the direction of absorbing polarized light components in the vertical direction of the first display surface; and a backlight, wherein the first polarizing plate and the second polarizing plate are configured to face each other across the liquid crystal element layer, and are configured to display in a normally black mode.

[0015] [Item 4] In the electronic device described in Item 3, the second polarizing plate has an absorption axis that is inclined downward from the normal direction of the first display surface toward the vertical direction of the first display surface.

[0016] [Item 5] In the electronic device described in Item 4, the first polarizing plate is disposed on the first display surface side of the liquid crystal element layer.

[0017] [Item 6] In the electronic device described in Item 5, a third polarizing plate is also provided, which is disposed on the side opposite to the liquid crystal element layer of the second polarizing plate, and has an absorption axis or a reflection axis parallel to the vertical direction of the first display surface.

[0018] [Item 7] In the electronic device described in Item 4, the second polarizing plate is disposed on the first display surface side of the liquid crystal element layer.

[0019] [Item 8] In the electronic device described in Item 7, the liquid crystal element layer is a liquid crystal element layer in a lateral electric field mode, and the liquid crystal molecules in the liquid crystal layer of the liquid crystal element layer have positive dielectric anisotropy and are pre-tilted in a manner having a late phase axis that is tilted downward from the normal direction of the first display surface to the vertical direction of the first display surface.

[0020] [Item 9] In the electronic device described in Item 8, a phase retardation plate is further provided, which is disposed between the liquid crystal element layer and a first polarizing plate or a second polarizing plate disposed on the side of the first display surface, the phase retardation plate having an upwardly inclined phase lag axis from the normal direction of the first display surface to the vertical direction of the first display surface.

[0021] [Item 10] In the electronic device described in Item 8 or 9, the liquid crystal element layer is configured to further apply a longitudinal electric field to the liquid crystal layer.

[0022] [Item 11] In any of the electronic devices described in Items 7 to 10, the liquid crystal element layer is configured to apply a horizontal electric field that is substantially parallel to the first display surface.

[0023] [Item 12] In any of the electronic devices described in items 7 to 11, the angle of inclination of the absorption axis of the second polarizing plate to the normal direction is smaller below the first display surface than above it.

[0024] [Item 13] In any of the electronic devices described in Items 7 to 12, the liquid crystal element layer has a plurality of pixels, each of the plurality of pixels having: a region with a color filter layer and a transparent region, wherein the liquid crystal layer in the transparent region is always in a black display state.

[0025] [Item 14] In any one of Items 7 to 13, the electronic device further comprises a third polarizing plate disposed on the side opposite to the liquid crystal element layer of the first polarizing plate, having an absorption axis or a reflection axis parallel to the horizontal direction of the first display surface.

[0026] [Item 15] In the electronic device described in Item 5 or 6, the liquid crystal element layer is a liquid crystal element layer in a lateral electric field mode, wherein the liquid crystal molecules within the liquid crystal layer of the liquid crystal element layer have positive dielectric anisotropy, and are configured to apply a lateral electric field that is substantially parallel to the vertical direction of the first display surface, and are configured to further apply a longitudinal electric field to the liquid crystal layer.

[0027] [Item 16] In the electronic device described in Item 15, the liquid crystal element layer has a plurality of pixels, and the longitudinal electric field is generated by electrodes of each of the plurality of pixels that are biased to the upper side of the vertical direction of the first display surface.

[0028] [Item 17] In the electronic device described in Item 5 or 6, the liquid crystal element layer is a liquid crystal element layer in a lateral electric field mode, the liquid crystal molecules in the liquid crystal layer of the liquid crystal element layer have negative dielectric anisotropy, the liquid crystal element layer is configured to apply a lateral electric field that is approximately parallel to the horizontal direction of the first display surface, and is configured to further apply a longitudinal electric field to the liquid crystal layer for display in HAN mode.

[0029] [Item 18] The electronic device described in any one of items 1 to 17 further includes a processor and a storage device.

[0030] Beneficial effects

[0031] According to an embodiment of the present invention, an electronic device is provided, which has a transmissive display panel and a reflective display panel, and improves the display quality of the reflective display panel. Attached Figure Description

[0032] Figure 1 This is a schematic perspective view of an electronic device 300 according to an embodiment of the present invention.

[0033] Figure 2 This is a perspective view schematically showing the configuration of the first display panel 100 and the second display panel 200 of the electronic device 300.

[0034] Figure 3 This is a schematic perspective view showing the configuration relationship between the polarization state of light emitted from the first display panel 100 in the electronic device 300 and the axis AXR of the polarized light absorbed by the second display panel 200.

[0035] Figure 4 This is a schematic perspective view showing the relationship between the polarization state of light emitted from the first display panel 910 in the comparative example electronic device 900 and the axis Abx of the polarized light absorbed by the second display panel 920.

[0036] Figure 5 This is a schematic exploded perspective view of the transmissive liquid crystal display panel 100A1.

[0037] Figure 6 This is a schematic exploded perspective view of the 100B organic EL display panel.

[0038] Figure 7 This is a schematic exploded perspective view of the transmissive liquid crystal display panel 100A2.

[0039] Figure 8 This is a schematic exploded perspective view of the 100A3 transmissive liquid crystal display panel.

[0040] Figure 9This is a schematic top view of the pixel PX of the liquid crystal element layer 110L1.

[0041] Figure 10 This is a schematic top view of the pixel PX of the liquid crystal element layer 110L2.

[0042] Figure 11 This is a schematic cross-sectional view of the pixel PX of the liquid crystal element layer 110L2.

[0043] Figure 12 This is a schematic cross-sectional view of the pixel PX of the liquid crystal element layer 110L3.

[0044] Figure 13 It is a side view that schematically shows the path of light reaching the observer when observing electronic device 300.

[0045] Figure 14 This is a schematic cross-sectional view showing the distribution of the absorption axes of the polarizing plate 126G.

[0046] Figure 15 This is a schematic top view of the pixel PX of the liquid crystal element layer 110L4.

[0047] Figure 16 This is a schematic isocontrast line diagram of liquid crystal element layer 110L4.

[0048] Figure 17 This is a schematic cross-sectional view (display mode) of the liquid crystal element layer 110L4.

[0049] Figure 18 This is a schematic cross-sectional view (illumination mode) of the liquid crystal element layer 110L4.

[0050] Figure 19 This is a schematic top view of the pixel PX of the liquid crystal element layer 110L5.

[0051] Figure 20 This is a schematic isocontrast line diagram of liquid crystal element layer 110L5.

[0052] Figure 21 This is a schematic cross-sectional view (display mode) of the liquid crystal element layer 110L5.

[0053] Figure 22 This is a schematic cross-sectional view (illumination mode) of the liquid crystal element layer 110L5.

[0054] Figure 23 This is a schematic top view of the pixel PX of the liquid crystal element layer 110L6.

[0055] Figure 24 This is a schematic isocontrast line diagram of the liquid crystal element layer 110L6.

[0056] Figure 25 This is a schematic cross-sectional view (display mode) of the liquid crystal element layer 110L6.

[0057] Figure 26 This is a schematic cross-sectional view (illumination mode) of the liquid crystal element layer 110L6. Detailed Implementation

[0058] The following describes an electronic device according to embodiments of the present invention with reference to the accompanying drawings. The electronic device according to embodiments of the present invention is not limited to the examples described below. Hereinafter, a foldable notebook computer having a first display panel as a main display and a second display panel as a reflective display panel will be illustrated as an example of an electronic device.

[0059] First, refer to Figures 1 to 3 The configuration and operation of the electronic device 300 according to an embodiment of the present invention will be described.

[0060] Figure 1 A schematic perspective view of an electronic device 300 according to an embodiment of the present invention is shown. The electronic device 300 includes a first display panel 100 having a first display surface 100DS and a second display panel 200 having a second display surface 200DS. The first display panel 100 is housed within a housing H1, and the second display panel 200 is housed within a housing H2. A processor and a storage device, for example, are housed within the housing H2. In addition, power circuitry, communication circuitry, and other circuitry similar to those in a known notebook computer are also housed within the housing H2. The housing H1 and housing H2 are connected in a foldable manner, for example, via a hinge (not shown). Specifically, the second display panel 200 is configured such that light emitted from the first display surface 100DS is incident on the second display surface 200DS, and in use, the first display surface 100DS and the second display surface 200DS are configured to form an interior angle of approximately 90° to approximately 120°.

[0061] Figure 2 The diagram shows a perspective view schematically illustrating the configuration of the first display panel 100 and the second display panel 200. Figure 3 A schematic perspective view showing the relationship between the polarization state of light emitted from the first display panel 100 and the configuration of the axis AXR of the polarized light absorbed by the second display panel 200.

[0062] In order to specify the configuration of the first display panel 100 and the second display panel 200, such as Figure 2As shown, XYZ coordinate systems are defined for the first display surface 100DS and the second display surface 200DS. The horizontal direction of each display surface 100DS and the second display surface 200DS is defined as the X-axis, the vertical direction as the Y-axis, and the direction orthogonal to the X-axis and Y-axis as the Z-axis. The normal direction of the first display surface 100DS is defined as N1, and the normal direction of the second display surface 200DS is defined as N2. The vectors N1 and N2, representing these normal directions, point towards the observer OBS. N1 and N2 are parallel to the Z-axis. When the first display surface 100DS and the second display surface 200DS are considered as the dial of a clock, the positive X-axis is at the 3 o'clock position, the negative X-axis is at the 9 o'clock position, the positive Y-axis is at the 12 o'clock position, and the negative Y-axis is at the 6 o'clock position.

[0063] like Figure 2 As shown, light rays DLu and DLd are emitted from the first display surface 100DS. Here, light ray DLu, emitted approximately upwards in the normal direction N1 relative to the first display surface 100DS, delivers the image displayed on the first display surface 100DS to the observer OBS. Light ray DLd, emitted approximately downwards in the normal direction N1 relative to the first display surface 100DS, is incident on the second display surface 200DS for reflected display on the second display panel 200. That is, light ray DLd is used as a front light source to illuminate the second display surface 200DS.

[0064] In the electronic device 300 of the embodiment of the present invention, the first display panel 100 is configured to include light emitted from the first display surface 100DS and incident on the second display surface 200DS, that is, the light DLd contains a large number of P-polarized light components, the second display panel 200 is a reflective display panel, and the second display surface 200DS has a polarizing plate arranged in a manner that absorbs the S-polarized light components of the incident light.

[0065] Next, refer to Figure 3 Please provide an explanation. Figure 3 This is a schematic perspective view showing the relationship between the polarization state of light emitted from the first display panel 100 and the polarization axis AXR of the second display panel 200.

[0066] like Figure 3 As shown, the light DLd emitted from the first display panel 100 toward the second display surface 200DS contains a significant amount of p-polarized light. The second display panel 200 has an absorption axis AXR parallel to the horizontal direction (X-axis) of the second display surface 200DS to absorb the s-polarized light component. Thus, when light containing a significant amount of p-polarized light is irradiated onto the second display panel 200, which has a polarizing plate configured to absorb the s-polarized light component, the reflective display quality of the second display panel 200 can be improved.

[0067] As is well known, the S-polarized light component, whose electric field vibrates perpendicularly to the incident plane (here parallel to the YZ plane), is easily reflected by the surface, while the P-polarized light component, whose electric field vibrates within the incident plane, is difficult to reflect by the surface. Therefore, the P-polarized light component incident on the second display surface 200DS is almost not reflected by the surface, and is not absorbed by the polarizer having an absorption axis AXR parallel to the horizontal direction (X-axis), thus being effectively used for reflective display in the second display panel 200.

[0068] In contrast, Figure 4 In the comparative example of the electronic device 900 shown, a good reflective display is not achieved. In the electronic device 900, the first display panel 910 emits light DLd containing a large amount of S-polarized light component from the first display surface 910DS to the second display surface 920DS of the second display panel 920, thus reflecting a large amount of it onto the second display surface 920DS. In addition, the light that is not reflected and enters the second display device 920 is absorbed by a polarizer having an absorption axis AXR parallel to the horizontal direction (X-axis), therefore, very little light is available for reflective display.

[0069] From the viewpoint of display quality, a reflective liquid crystal display panel is preferred for use as the second display panel 200. Any known reflective liquid crystal display panel can be widely used as long as it has a polarizer with an absorption axis AXR parallel to the horizontal direction (X-axis). Alternatively, depending on the application, a reflective display panel other than a liquid crystal display panel can also be used.

[0070] The following describes a display panel suitable for use as the primary display panel.

[0071] Figure 5 An exploded perspective view of a transmissive liquid crystal display panel 100A1 suitable for use as a first display panel is shown.

[0072] The transmissive liquid crystal display panel 100A1 includes: a liquid crystal element layer 110L; a first polarizing plate 122 having an absorption axis AX1 parallel to the horizontal direction (X-axis) of the first display surface 100DS; a second polarizing plate 124 having an absorption axis AX2 in the direction of absorbing the polarization component (P-polarization component) in the vertical direction of the first display surface 100DS; and a backlight 180. The first polarizing plate 122 and the second polarizing plate 124 are arranged opposite each other with a gap between them and the liquid crystal element layer 110L, and the transmissive liquid crystal display panel 100A1 displays in a normally black mode. The light emitted from the first display surface 100DS of the transmissive liquid crystal display panel 100A1 contains a greater proportion of P-polarization components.

[0073] Here, the first polarizing plate 122 is disposed on the first display surface 100DS side of the liquid crystal element layer 110L, and the absorption axis AX2 of the second polarizing plate 124 is parallel to the vertical direction (Y-axis) of the first display surface 100DS. As illustrated below, the arrangement of the first polarizing plate 122 and the second polarizing plate 124 is not limited to this. In addition, the absorption axis AX2 of the second polarizing plate 124 only needs to absorb the P-polarized light component of the light emitted toward the second display surface 200DS. Therefore, it may also have an absorption axis that is inclined downward (in the Y-axis direction in the YZ plane, the 6 o'clock direction) from the normal direction N1 of the first display surface 100DS toward the vertical direction of the first display surface 100DS. Furthermore, the cylinder in the figure represents the direction of the transition moment of light absorption of dichroic pigment molecules (parallel to the absorption axis), but the polarizing plate is not limited to a dichroic polarizing plate.

[0074] The liquid crystal element layer 110L can be a liquid crystal element layer used in a known transmissive liquid crystal display device, such as an active matrix type liquid crystal element layer. As described later, the liquid crystal element layer 110L has, per pixel: a back substrate, a front substrate, a liquid crystal layer disposed between the back substrate and the front substrate, and an electrode structure for applying a voltage for display to the liquid crystal layer. The electrode structure includes, for example, a pixel electrode and a common electrode (also called an opposing electrode). In the liquid crystal element layer 110L of lateral electric field mode such as FFS mode, the pixel electrode and the common electrode are formed on the same substrate. In the liquid crystal element layer 110L of vertical electric field mode such as VA mode and HAN mode, the pixel electrode and the common electrode are formed on the main surface of the back substrate and the front substrate, which are disposed opposite to each other with respect to the liquid crystal layer. The liquid crystal element layer 110L may have driving circuits (source driver, gate driver) and wiring (source bus, gate bus) for supplying voltage to the pixel electrode and the common electrode. In addition, the liquid crystal element layer 110L may have a color filter layer for color display. The structure of the liquid crystal element layer 110L is well known, so detailed descriptions are omitted.

[0075] Alternatively, a transmissive display panel having a transmissive display element layer (e.g., an electrophoretic display element layer or an electrowetting display element layer) other than the liquid crystal element layer 110L can also be used as the first display panel.

[0076] Figure 6 An exploded perspective view of an organic EL display panel 100B suitable for use as a first display panel is shown.

[0077] The organic EL display panel 100B has an organic EL element layer 110E and a circular polarizer 120CP disposed on the first display surface 100DS side of the organic EL element layer 110E. The circular polarizer 120CP has: a first polarizer 122 having an absorption axis AX1 parallel to the horizontal direction (X-axis), and a quarter-wave plate (1 / 4λ plate) 132 disposed on the organic EL element layer 110E side of the first polarizer 122. The late phase axis SX1 of the 1 / 4λ plate 132 is arranged at a 45° angle to the absorption axis AX1 of the circular polarizer 120C. The light emitted from the first display surface 100DS of the organic EL display panel 100B contains a significant amount of p-polarized light.

[0078] The following describes other examples of transmissive liquid crystal display panels suitable for use as the first display panel. For simplicity, illustrations of the backlight are omitted below.

[0079] Figure 7 A schematic exploded perspective view of the transmissive liquid crystal display panel 100A2 is shown. Figure 8 An exploded perspective view of a transmissive liquid crystal display panel 100A3 is shown.

[0080] Both liquid crystal display panels 100A2 and 100A3 include: a liquid crystal element layer 110L; a first polarizing plate 122 having an absorption axis AX1 parallel to the horizontal direction (X-axis) of the first display surface 100DS; a second polarizing plate 126 having an absorption axis AX3 in the direction of absorbing the polarizing component (P-polarizing component) in the vertical direction of the first display surface 100DS; and a backlight (not shown). The second polarizing plate 126 has an absorption axis AX3 extending from the normal direction of the first display surface 100DS to the vertical direction (Y-axis) of the first display surface 100DS.

[0081] It slopes downwards.

[0082] exist Figure 7 In the liquid crystal display panel 100A2 shown, a first polarizing plate 122 is disposed on the first display surface 100DS side of the liquid crystal element layer 110L, and a second polarizing plate 126 having an absorption axis AX3 that is inclined downward from the normal direction of the first display surface 100DS toward the vertical direction (Y-axis) of the first display surface 100DS is disposed on the side of the liquid crystal element layer 110L opposite to the first display surface 100DS. The liquid crystal display panel 100A2 also has an optional third polarizing plate 124, which has an absorption axis AX2 parallel to the vertical direction (Y-axis) of the first display surface 100DS.

[0083] The absorption axis AX3 of the second polarizing plate 126 is inclined at approximately 45° downwards from the normal direction of the first display surface 100DS towards the vertical direction (Y-axis) of the first display surface 100DS. Therefore, for the light ray DLu emitted from the first display surface 100DS toward the observer, the absorption axis AX3 is approximately orthogonal to the absorption axis AX1. Thus, a generally good display can be achieved through the light ray DLu.

[0084] On the other hand, for the light DLd emitted from the first display surface 100DS toward the second display surface 200DS, the absorption axis AX3 of the second polarizing plate 126 is parallel to the traveling direction and will not be absorbed by the second polarizing plate 126. Furthermore, the absorption axis AX1 of the first polarizing plate 122 is orthogonal to the vibration direction of the electric field of the P-polarized component, and therefore will not be absorbed by the first polarizing plate 122. That is, the intensity of the light DLd emitted toward the second display surface 200DS does not depend on the state of the liquid crystal element layer 110L. Therefore, the liquid crystal display panel 100A2 can irradiate P-polarized light onto the second display surface 200DS of the reflective display panel 200 regardless of the display state. The liquid crystal display panel 100A2 does not have the characteristic of emitting P-polarized light from the first display surface 100DS toward the second display surface 200DS. Figure 5 The intensity of the light rays (ray DLu and ray DLd) emitted from the first display surface 100DS of the liquid crystal display panel 100A1 shown depends on the display state.

[0085] The second polarizing plate 126, which has an inclined absorption axis AX3, can be manufactured, for example, by curing a guest-host type liquid crystal material using the technique described in Shinya Watanabe, et al., "Vertically and Inclinedly Oriented Polarizers for Viewing Angle Control", SID Symposium Digest of Technical Papers, Volume 52, Number 1, May 2021, pp. 757-760. The tilt angle from the normal direction of the first display surface 100DS downwards in the vertical direction (Y-axis) of the first display surface 100DS can be appropriately set according to the size of the first display surface 100DS and the second display surface 200DS, and the size of the interior angle, for example, in the range of 20° or more and 40° or less.

[0086] When the second polarizing plate 126 cannot achieve sufficient polarization (S-polarization), the polarization can be increased by providing a third polarizing plate 124. In this case, the polarization of the third polarizing plate 124 can be lower than that of polarizing plates used in typical liquid crystal display devices. A high polarization improves contrast; otherwise, it leads to a decrease in transmittance. Therefore, if the polarization is increased beyond a certain point, the disadvantage of decreased transmittance becomes more pronounced. Polarizing plates used in ordinary liquid crystal display devices have a polarization of 99.9% or higher. Here, since it is used with the second polarizing plate 126, a polarizing plate with a polarization of, for example, 99.0% or lower can be used for the third polarizing plate 124. Alternatively, a reflective polarizing plate having a reflection axis parallel to the vertical direction (Y-axis) of the first display surface 100DS can be used instead of the third polarizing plate 124. By using a reflective polarizing plate, light utilization efficiency can be improved.

[0087] exist Figure 8 In the liquid crystal display panel 100A3 shown, a second polarizing plate 126, having an absorption axis AX3 that slopes downwards from the normal direction of the first display surface 100DS towards the vertical direction (Y-axis) of the first display surface 100DS, is disposed on the first display surface 100DS side of the liquid crystal element layer 110L. A first polarizing plate 122 is disposed on the side of the liquid crystal element layer 110L opposite to the first display surface 100DS side. The liquid crystal display panel 100A3 also has an optional third polarizing plate 128, which is disposed on the side of the first polarizing plate 122 opposite to the liquid crystal element layer 110L, and has an absorption axis AX1 parallel to the horizontal direction (X-axis) of the first display surface 100DS. The third polarizing plate 128 exhibits the same effect as the third polarizing plate 124 in the liquid crystal display panel 100A2.

[0088] In the liquid crystal display panel 100A3, the S-polarized component is absorbed by the first polarizing plate 122, which has an absorption axis AX1, and guided to the liquid crystal element layer 110L. Then, for the light ray DLu emitted from the liquid crystal element layer 110L through the second polarizing plate 126 and towards the observer, the absorption axis AX3 is approximately orthogonal to the absorption axis AX1. Therefore, a generally good display is possible through the light ray DLu.

[0089] On the other hand, for the light DLd emitted from the first display surface 100DS toward the second display surface 200DS, the absorption axis AX3 of the second polarizer 126 is parallel to the direction of travel and is not absorbed by the second polarizer 126. When using a reflective polarizer as the third polarizer, the liquid crystal display panel 100A3 can improve the intensity of the light DLd compared to the liquid crystal display panel 100A2. However, in the liquid crystal display panel 100A3, depending on the state of the liquid crystal element layer 110L, the light passing through the liquid crystal element layer 110L contains an S-polarized component. Therefore, there is a concern that surface reflection under the second display surface 200DS may lead to a decrease in display quality.

[0090] There are no particular limitations on the operating mode (display mode) of the liquid crystal element layer 110L. It can use a lateral electric field mode (e.g., FFS (edge ​​field switching) mode) or a vertical electric field mode (e.g., VA (vertical alignment) mode, HAN (hybrid nematic) mode, TN (twisted nematic) mode, etc. For example, a liquid crystal element layer 110L combining FFS mode, a polarizing plate 122 for a general liquid crystal display device, and a tilted polarizing plate 126 can achieve a contrast ratio of 1000:1 on the front side.

[0091] Next, refer to Figures 9-26 This illustrates an example of a 110L liquid crystal element layer.

[0092] Figure 9 A schematic top view of a pixel PX in a liquid crystal element layer 110L1 is shown. The liquid crystal element layer 110L1 is a liquid crystal element layer of a known lateral electric field mode (e.g., FFS mode), and the configuration other than the comb-shaped pixel electrode 12 is omitted. Figure 9 Reference numeral BM in the figure represents a black matrix that blocks light from the gate lines. The liquid crystal element layer 110L has multiple pixels PX, each pixel having: a region PX-C with a color filter layer; and a transparent region PX-T that transmits visible light (white) across the entire wavelength range. The liquid crystal layer within the transparent region PX-T is always in a black display state. That is, there is no pixel electrode 12 within the transparent region PX-T, and the liquid crystal molecules LC maintain their initial alignment state. By providing a transparent region PX-T within each pixel, the amount of light irradiated onto the reflective display panel can be increased without reducing the display quality of the normally black liquid crystal display panel (e.g., liquid crystal display panel 100A3).

[0093] Figure 10 A schematic top view showing the pixel PX of the liquid crystal element layer 110L2 is shown. Figure 11 A schematic cross-sectional view of a pixel PX in liquid crystal element layer 110L2 is shown. Liquid crystal element layer 110L2 is also a liquid crystal element layer of a known lateral electric field mode (e.g., FFS mode), and detailed description is omitted. Figure 11In the figure, SB indicates a substrate, and SBC indicates a substrate with a filter layer.

[0094] The liquid crystal element layer 110L2 is a lateral electric field mode liquid crystal element layer. The liquid crystal molecules LC within the liquid crystal layer 10 of the liquid crystal element layer have positive dielectric anisotropy and are pre-tilted with a late phase axis SXL that is tilted downward from the normal direction of the first display surface 100DS to the vertical direction (Y-axis) of the first display surface 100DS. The pretilt angle θp is limited by the alignment film 22, and is preferably 20° or more, for example. When the pretilt angle is 20°, the influence of the optical anisotropy of the liquid crystal layer 10 can be largely eliminated for light incident from air at an angle of approximately 30° (60° from the normal). In this way, by giving the liquid crystal molecules LC a high pretilt angle, the change in polarization state caused by the state of the liquid crystal element layer 110L2 can be suppressed. Therefore, for example, the reflective display panel can be sufficiently illuminated regardless of the display state of the liquid crystal display panel 100A3.

[0095] Furthermore, a phase retardation plate 134 may also be disposed between the liquid crystal element layer 110L2 and the first polarizing plate 122 or the second polarizing plate 126 disposed on the first display surface side 100DS. The phase retardation plate 134 has a late phase axis SX1 that is inclined upward from the normal direction of the first display surface 100DS to the vertical direction (Y-axis) of the first display surface 100DS. When the liquid crystal molecules LC are tilted, the left and right viewing angles become slightly narrower, but by providing such a phase retardation plate (negative A plate) 134, the left and right viewing angles can be widened.

[0096] Figure 12 This is a schematic cross-sectional view showing the pixel PX of the liquid crystal element layer 110L3. Like the liquid crystal element layer 110L2, the liquid crystal element layer 110L3 is a liquid crystal element layer of a known lateral electric field mode (e.g., FFS mode), and in addition to the liquid crystal element layer 110L2, it also has electrodes 14 and 16 that are capable of applying a longitudinal electric field to the liquid crystal layer 10.

[0097] By applying a longitudinal electric field to the liquid crystal layer 10, similar to the liquid crystal element layer 110L2, changes in polarization state caused by the state of the liquid crystal element layer 110L3 can be suppressed. Therefore, for example, the reflective display panel can be fully illuminated regardless of the display state of the liquid crystal display panel 100A3.

[0098] If such a method of controlling the tilt angle of liquid crystal molecules LC by means of a longitudinal electric field is used, then, for example by means of the dividing electrode 16, the intensity of the longitudinal electric field applied to the liquid crystal layer 10 can be changed according to the position of the liquid crystal element layer 110L3.

[0099] For example, Figure 13This is a side view schematically showing the path of light reaching the observer when viewing the electronic device 300, which is a notebook computer. Reflective liquid crystal display panels exhibit reflective properties due to the large contribution of the orthographic reflection component. Figure 13 The image shows the optical path of the positively reflected light.

[0100] like Figure 13 As shown, the angle of light exiting the transmissive display panel 100 (the angle from the normal direction of the first display surface 100DS) from the observer OBS is smaller below the first display surface 100DS than above it. For example, when the sizes of display panels 100 and 200 are each set to 20cm, the position of the observer OBS is set to 40cm from the left end of the reflective display panel 200, and the height is set to 40cm, the angle of light exiting the observer OBS is approximately 45° above the first display surface 100DS and approximately 34° below it.

[0101] The tilt angle of the liquid crystal molecules LC in the liquid crystal element layer 110L3 is preferably controlled to be smaller at the bottom than at the top, in accordance with the above-mentioned distribution of the emission angle.

[0102] For the same reason, Figure 7 and Figure 8 In the second polarizing plate 126 with the absorption axis tilted as shown, the tilt angle of the absorption axis AX3 from the normal direction of the first display surface 100DS is preferably smaller below the first display surface 100DS than above it. Figure 14 This is a schematic cross-sectional view showing the distribution of the absorption axes of a polarizing plate 126G with such a distribution of absorption axes.

[0103] Figure 14 The tilt angles θ1, θ2, θ3 of the tilted absorption axes AX3_1, AX3_2, AX3_3 of the second polarizing plate 126G from the normal direction N1 are smaller below the first display surface than above it, i.e., θ1>θ2>θ3. Thus, by progressively or continuously reducing the tilt angle θ of the absorption axis AX3 from above to below the first display surface 100DS, the reflective display panel 200 can be effectively illuminated, thereby providing a higher quality reflective display.

[0104] Next, refer to Figure 15 ~ Figure 26 This indicates that it is suitable as Figure 5 An example of the liquid crystal element layer used in the liquid crystal element layer 110L of the transmissive liquid crystal display panel 100A1 shown.

[0105] First, refer to Figures 15-18 This indicates that the liquid crystal element layer is 110L4. Figure 15 This is a schematic top view of the pixel PX of the liquid crystal element layer 110L4. Figure 16 This is a schematic isocontrast line diagram of liquid crystal element layer 110L4. Figure 17 This is a schematic cross-sectional view (display mode) of the liquid crystal element layer 110L4. Figure 18 This is a schematic cross-sectional view (illumination mode) of the liquid crystal element layer 110L4.

[0106] By controlling the operation of the liquid crystal element layer 110L4, it is possible to switch between a display mode that displays based on the transmissive liquid crystal display panel 100A1 and an illumination mode that actively illuminates the reflective display panel 200.

[0107] The liquid crystal element layer 110L4 is a liquid crystal element layer in a lateral electric field mode (e.g., FFS mode). The liquid crystal molecules LC (Δn=0.1) within the liquid crystal layer 10 have positive dielectric anisotropy, and are configured to apply a lateral electric field that is approximately parallel to the vertical direction of the first display surface 100DS, and are also configured to further apply a longitudinal electric field to the liquid crystal layer 10. Figure 15 As shown, pixel PX has a shape that is elongated in the horizontal direction (X-axis direction), and the leaked light LL leaks in the vertical direction (Y-axis direction), indicating that... Figure 16 The equal contrast lines are shown. For example, the size of one pixel is set to 20.2μm vertically × 60.55μm horizontally, the width of the comb electrode is 4μm, the distance between electrodes is 4μm, and the thickness (unit thickness) of the liquid crystal layer 10 is 3.3μm.

[0108] The liquid crystal element layer 110L4 has a common electrode 14 and a pixel electrode 12 on the substrate SB, and an electrode 16 for applying a longitudinal electric field to the liquid crystal layer 10 on the filter substrate SBC. The filter substrate SBC has a filter layer disposed opposite to the substrate SB, separated from the liquid crystal layer 10. The liquid crystal element layer 110L4 has an insulating layer 1L and alignment films 22 and 24.

[0109] like Figure 17 As shown, by applying a voltage between the pixel electrode 12 and the common electrode 14, an edge electric field is generated, and the liquid crystal display panel operates as a typical FFS mode. On the other hand, as... Figure 18 As shown, if a voltage is also applied to the opposing electrode 16, generating a longitudinal electric field, the liquid crystal molecules, which are normally horizontally aligned, rotate in a tilted, upright state under the influence of the longitudinal electric field, thus allowing light to intentionally leak in a left-right tilted direction. This leaked light is used as illumination for a reflective display panel. At this time, when viewed from the front, the display in the normal display mode can be observed.

[0110] Figures 19-22 Explanation of liquid crystal element layer 110L5. Figure 19 This is a schematic top view of the pixel PX of the liquid crystal element layer 110L5. Figure 20This is a schematic isocontrast line diagram of liquid crystal element layer 110L5. Figure 21 This is a schematic cross-sectional view (display mode) of the liquid crystal element layer 110L5. Figure 22 This is a schematic cross-sectional view (illumination mode) of the liquid crystal element layer 110L5.

[0111] like Figure 19 , Figure 21 , Figure 22 As shown, in liquid crystal element layer 110L4, the electrode 16 of liquid crystal element layer 110L5 is biased upwards in the vertical direction (Y-axis direction) of the first display surface 100DS of the pixel. As a result, if a longitudinal electric field is generated, the liquid crystal molecules LC rise obliquely along the electric field, therefore, as... Figure 20 As shown in the equal contrast line graph, the viewing angle characteristics deviate, which can increase the intensity of light incident on the reflective display panel. Additionally, it can simultaneously suppress unwanted light leakage upwards.

[0112] By employing this configuration, the intensity of the illumination light irradiated onto the reflective display panel can be increased by making the area (e.g., the width in the vertical direction) of the electrode 16 within the pixel larger from the top of the display surface downwards.

[0113] Reference Figures 23-25 Explanation of liquid crystal element layer 110L6. Figure 23 This is a schematic top view of the pixel PX of the liquid crystal element layer 110L6. Figure 24 This is a schematic isocontrast line diagram of the liquid crystal element layer 110L6. Figure 25 This is a schematic cross-sectional view (display mode) of the liquid crystal element layer 110L6. Figure 26 This is a schematic cross-sectional view (illumination mode) of the liquid crystal element layer 110L6.

[0114] Like liquid crystal element layers 110L4 and 110L5, liquid crystal element layer 110L6 is a lateral electric field mode (e.g., FSS mode). The liquid crystal molecules within the liquid crystal layer 10 of liquid crystal element layer 110L6 have negative dielectric anisotropy, thus applying a lateral electric field approximately parallel to the horizontal direction (X-axis direction) of the first display surface 100DS. Like liquid crystal element layer 110L4, liquid crystal element layer 110L6 has electrodes 16 for further applying a vertical electric field to the liquid crystal layer 10, for display in HAN mode. Figure 23 As shown, pixel PX has a shape that is elongated in the vertical direction (Y-axis direction), and the leaked light LL leaks in the vertical direction (Y-axis direction), indicating that... Figure 24 The lines with equal contrast are shown.

[0115] In the HAN mode, the liquid crystal molecules LC of the liquid crystal layer 10 of the liquid crystal element layer 110L6 are horizontally aligned through the alignment film 22 on the edge electric field side and vertically aligned through the alignment film 24 on the color substrate side. When a vertical electric field is applied, the liquid crystal molecules LC are horizontally aligned. In the display mode, such as... Figure 25 As shown, edge electric fields and longitudinal electric fields are applied. In the lighting mode, as... Figure 26 As shown, only the edge electric field is used.

[0116] The liquid crystal element layer 110L6 is characterized by an increased amount of light leakage in the vertical direction, resulting in high performance as an illumination source. On the other hand, when a vertical electric field is applied, due to the influence of the alignment constraint force, the liquid crystal molecules on the vertical alignment side tend to be unable to become horizontal, leading to a deterioration in viewing angle characteristics.

[0117] Practicality in industry

[0118] The electronic device according to embodiments of the present invention is capable of high-quality reflective display. The electronic device of the present invention is suitable for use as a notebook computer.

[0119] Explanation of reference numerals in the attached figures

[0120] 100: First display panel, 200: Second display panel, 100DS: First display surface, 200DS: Second display surface, AXR, AX1: Absorption axis, SX1: Delayed phase axis.

Claims

1. An electronic device, characterized in that, include: A first display panel has a first display surface; A second display panel has a second display surface and is configured such that light emitted from the first display surface is incident on the second display surface. The first display panel is configured such that the light emitted from the first display surface and incident on the second display surface contains a large amount of P-polarized light components. The second display panel is a reflective display panel, and has a polarizing plate on the second display surface, which is configured to absorb the S-polarized component of the incident light. The first display panel is a transmissive display panel and has the following characteristics: The system comprises: a liquid crystal element layer; a first polarizing plate having an absorption axis parallel to the horizontal direction of the first display surface; a second polarizing plate having an absorption axis in a direction that absorbs polarized light components in the vertical direction of the first display surface; and a backlight source, wherein the first polarizing plate and the second polarizing plate are configured to face each other across the liquid crystal element layer, and are configured to display in a normally black mode. The second polarizing plate has an absorption axis that slopes downward from the normal direction of the first display surface toward the vertical direction of the first display surface.

2. The electronic device according to claim 1, characterized in that, The first polarizing plate is disposed on the first display surface side of the liquid crystal element layer.

3. The electronic device according to claim 2, characterized in that, It also has a third polarizing plate, which is disposed on the side opposite to the liquid crystal element layer of the second polarizing plate, and has an absorption axis or a reflection axis parallel to the vertical direction of the first display surface.

4. The electronic device according to claim 1, characterized in that, The second polarizing plate is disposed on the first display surface side of the liquid crystal element layer.

5. The electronic device according to claim 4, characterized in that, The liquid crystal element layer is a lateral electric field mode liquid crystal element layer. The liquid crystal molecules in the liquid crystal layer of the liquid crystal element layer have positive dielectric anisotropy and are pre-tilted in a manner with a lag axis that is tilted downward from the normal direction of the first display surface to the vertical direction of the first display surface.

6. The electronic device according to claim 5, characterized in that, It also has a phase retardation plate disposed between the liquid crystal element layer and the first polarizing plate or the second polarizing plate disposed on the first display surface side, the phase retardation plate having a phase lag axis that is inclined upward from the normal direction of the first display surface to the vertical direction of the first display surface.

7. The electronic device according to claim 5 or 6, characterized in that, The liquid crystal element layer is configured to further apply a longitudinal electric field to the liquid crystal layer.

8. The electronic device according to any one of claims 4 to 6, characterized in that, The liquid crystal element layer is configured to apply a horizontal electric field parallel to the first display surface.

9. The electronic device according to any one of claims 4 to 6, characterized in that, The angle of inclination of the absorption axis of the second polarizing plate relative to the normal direction is smaller below the first display surface than above it.

10. The electronic device according to any one of claims 4 to 6, characterized in that, The liquid crystal element layer has multiple pixels, each of which has a region with a color filter layer and a transparent region, wherein the liquid crystal layer in the transparent region is always in a black display state.

11. The electronic device according to any one of claims 4 to 6, characterized in that, It also has a third polarizing plate, which is disposed on the side opposite to the first polarizing plate and the liquid crystal element layer, and has an absorption axis or a reflection axis parallel to the horizontal direction of the first display surface.

12. The electronic device according to claim 2 or 3, characterized in that, The liquid crystal element layer is a lateral electric field mode liquid crystal element layer. The liquid crystal molecules in the liquid crystal layer of the liquid crystal element layer have positive dielectric anisotropy, which is configured to apply a lateral electric field parallel to the vertical direction of the first display surface, and is configured to further apply a longitudinal electric field to the liquid crystal layer.

13. The electronic device according to claim 12, characterized in that, The liquid crystal element layer has multiple pixels. The longitudinal electric field is generated by electrodes of each of the plurality of pixels that are biased to the upper side of the vertical direction of the first display surface.

14. The electronic device according to claim 2 or 3, characterized in that, The liquid crystal element layer is a lateral electric field mode liquid crystal element layer. The liquid crystal molecules in the liquid crystal layer of the liquid crystal element layer have negative dielectric anisotropy. The liquid crystal element layer is configured to apply a lateral electric field parallel to the horizontal direction of the first display surface, and is configured to further apply a longitudinal electric field to the liquid crystal layer for display in HAN mode.

15. The electronic device according to any one of claims 1 to 6, characterized in that, It also has a processor and storage device.

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