Mirror display

Abstract

To provide a mirror display having a simple configuration, which exhibits a mirror function in a normal direction and a signage function in an oblique direction, and can prevent peeping from an oblique direction. [Solution] A mirror display comprising a liquid crystal panel, a reflective polarizer arranged on the front side of the liquid crystal panel, and a backlight arranged on the back side of the liquid crystal panel, wherein, when the display surface of the mirror display is held upright, and when a plane that is perpendicular to the display surface and includes the left and right directions of the display surface is taken as a reference plane, the brightness of the backlight when observed from the normal direction of the display surface is lower than the brightness when observed from a direction along the reference plane that is at an angle of 30° or more and 60° or less with respect to the normal direction of the display surface.

Description

[Technical Field]

[0001] The present disclosure relates to a mirror display. [Background technology]

[0002] In recent years, mirror displays with signage functions that combine a mirror function with an advertising function have been studied. For example, methods have been studied to achieve the mirror function by equipping the display with a human sensor and projecting a person's image when they stand in front of the display (e.g., Patent Documents 1 and 2), or by turning the backlight or panel to a black screen (e.g., Patent Documents 3 and 4).

[0003] Patent Document 1 discloses a mirror display having a mirror surface that reflects the front, the mirror surface comprising a half mirror that reflects the front, a display device that is arranged behind the half mirror and faces the back of the half mirror to display information by emitting light, a human body detection sensor that detects the presence or absence of a person in front of the half mirror, and a thermometer that measures body temperature non-contact, wherein the display surface of the display device overlaps with the half mirror by 70% or more in a front view, and the display device is provided with a control unit that controls the display device, and the control unit displays information on the screen of the display device only when it is determined that the human body detection sensor has detected a person, and controls the display device to display body temperature information detected by the thermometer on the display surface of the display device.

[0004] Patent Document 2 discloses a multi-function image display device comprising a display device having a screen capable of displaying an image, a half mirror covering the screen, a control means for controlling the ON / OFF switching of the image display on the display device, and a human presence sensor for detecting a person entering a predetermined range including the display device, wherein the control means turns ON the image display on the display device when the human presence sensor detects that a person has entered the predetermined range, and when the image display on the display device is OFF, the half mirror functions as a mirror, and when the image display on the display device is ON, the display device functions as an image display device using the image seen through the half mirror.

[0005] Patent document 3 discloses a mirror-type display device that includes a half mirror and a liquid crystal display placed opposite the back surface of the half mirror, and that displays an image on the liquid crystal display so that it is superimposed on a mirror image reflected in front of the half mirror, the liquid crystal display having a liquid crystal display panel and a direct backlight consisting of light-emitting elements arranged in a grid pattern, and the backlight is controlled by a local dimming method so that the closer the pixel groups in the liquid crystal display panel that face each of the light-emitting elements become to black, the darker each of the light-emitting elements becomes.

[0006] Patent Document 4 discloses a mirror optical element including a monitor display element that emits light as image light oscillating in a first direction in an image display state, a reflective polarizing plate that is provided on the display surface side of the monitor display element and transmits light oscillating in the first direction and reflects light oscillating in a second direction perpendicular to the first direction, an absorptive polarizing plate that is provided on the display surface side of the reflective polarizing plate and transmits light oscillating in the first direction and absorbs light oscillating in the second direction, and a liquid crystal cell that is provided between the reflective polarizing plate and the absorptive polarizing plate, and the mirror optical element includes a liquid crystal cell that reflects the light oscillating in the first direction and the light oscillating in a second direction perpendicular to the first direction. A mirror display device is disclosed that can switch between a reflective state in which light vibrating in the first direction from the absorbing polarizer side is converted by the liquid crystal cell to vibrate in the second direction, reflected by the reflective polarizer, and converted by the liquid crystal cell to vibrate in the first direction and emitted from the absorbing polarizer, and a transmissive state in which light vibrating in the first direction from the reflective polarizer side passes through the liquid crystal cell while still vibrating in the first direction and is emitted from the absorbing polarizer, and the orientation of the preferential transmission direction of the mirror optical element is set according to the user's viewing direction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2022-094194 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-053277 [Patent Document 3] Registered Utility Model No. 3217121 [Patent Document 4] Japanese Patent Application Publication No. 2018-205363 Summary of the Invention [Problem to be solved by the invention]

[0008] The present inventors have investigated how to realize a mirror display with a simple configuration that functions as a mirror when viewed from the front and has a signage function that displays advertisements and the like when viewed from an oblique direction. Let us assume that a user viewing the mirror display from the front and desiring the mirror function is User A, and another user viewing the mirror display from an oblique direction is User B. When displaying advertisements and the like on the mirror display for User B to view, User A may have difficulty viewing his or her own mirror image. For example, Patent Documents 3 and 4 discuss reducing the brightness of the backlight or turning the screen black when the mirror function is desired, but this results in complex and costly devices. Furthermore, turning the screen black may allow User B to view User A's mirror image, i.e., spy on the user, depending on the viewing angle. None of Patent Documents 1 to 4 consider the effectiveness of preventing peeping, leaving room for further investigation.

[0009] The present invention has been made in consideration of the above-mentioned current situation, and aims to provide a mirror display that has a simple configuration, exhibits a mirror function in the normal direction, exhibits a signage function in oblique directions, and can prevent peeking from oblique directions. [Means for solving the problem]

[0010] (1) One embodiment of the present invention is a mirror display comprising a liquid crystal panel, a reflective polarizer arranged on the front side of the liquid crystal panel, and a backlight arranged on the back side of the liquid crystal panel, wherein, when the display surface of the mirror display is set up vertically, a plane that is perpendicular to the display surface and includes the left and right directions of the display surface is taken as a reference plane, and the luminance of the backlight when observed from the normal direction of the display surface is lower than the luminance when observed from a direction along the reference plane that is at an angle of 30° or more and 60° or less with respect to the normal direction of the display surface.

[0011] (2) In addition to the configuration of (1) above, one embodiment of the present invention is a mirror display configured so that, when the backlight is turned on, a user positioned in the normal direction of the display surface of the mirror display can see their own mirror image, and a user observing from a direction along the reference plane at an angle of 30° or more and 60° or less with respect to the normal direction of the display surface can see the image output from the display panel.

[0012] (3) Furthermore, one embodiment of the present invention is a mirror display having, in addition to the configuration of (1) or (2) above, a first linear polarizer between the liquid crystal panel and the reflective polarizer, and a second linear polarizer between the liquid crystal panel and the backlight.

[0013] (4) Furthermore, in addition to the configuration of (3), an embodiment of the present invention is a mirror display, in which the absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer are perpendicular to each other.

[0014] (5) Furthermore, in addition to the configuration of (3), an embodiment of the present invention is a mirror display, in which the absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer are parallel to each other.

[0015] (6) Furthermore, one embodiment of the present invention is a mirror display, in addition to the configuration of (4) or (5) above, wherein either the absorption axis of the first linear polarizer or the absorption axis of the second linear polarizer is parallel to or perpendicular to the left-right direction of the display surface.

[0016] (7) Furthermore, in addition to the configuration of (4) or (5), one embodiment of the present invention is a mirror display, wherein at least one of the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer forms an angle of approximately 45° with the left-right direction of the display surface.

[0017] (8) Furthermore, in addition to the configuration of (3), one embodiment of the present invention is a mirror display, wherein at least one of the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer forms an angle of approximately 45° with the left-right direction of the display surface, the absorption axis of the second linear polarizer and the absorption axis of the first linear polarizer are orthogonal to each other, and the absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer are orthogonal to each other.

[0018] (9) Furthermore, one embodiment of the present invention is a mirror display in which, in addition to the configuration of any one of (1) to (8) above, the backlight has light-emitting elements arranged along a direction perpendicular to the left-right direction of the display surface, and a plurality of linear convex portions arranged along the left-right direction of the display surface and extending in a direction perpendicular to the left-right direction of the display surface, and each of the plurality of linear convex portions has an inclined surface that slopes toward the left-right direction of the display surface. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a mirror display with a simple configuration that exhibits a mirror function in the normal direction and a signage function in an oblique direction, and that can prevent peeping from an oblique direction. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic cross-sectional view of a mirror display according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram illustrating the reference surface of the mirror display. [Figure 3] FIG. 2 is a front view of the mirror display according to the embodiment placed horizontally. [Figure 4] FIG. 2 is a front view of the mirror display according to the embodiment placed vertically. [Figure 5] 1 is a schematic diagram illustrating a mirror display from above, illustrating the mirror function, signage function, and anti-peeping effect. FIG. [Figure 6] FIG. 10 is a cross-sectional view of a backlight illustrating the intensity of emitted light. [Figure 7]FIG. 1 is a cross-sectional view showing an example of an edge-light type backlight. [Figure 8] FIG. 8 is a schematic plan view of the backlight shown in FIG. [Figure 9] FIG. 1 is a cross-sectional view showing an example of a direct-type backlight. [Figure 10] FIG. 10 is a schematic plan view of the backlight shown in FIG. [Figure 11] 1 is a graph showing the light output intensity of a backlight used in an example and a backlight used in a comparative example. [Figure 12] FIG. 2 is an exploded perspective view illustrating the shaft configuration and the amount of light emitted in the first embodiment. [Figure 13] FIG. 10 is an exploded perspective view illustrating the shaft configuration and the amount of light output according to the second embodiment. [Figure 14] FIG. 10 is an exploded perspective view illustrating the shaft configuration and the amount of light emitted in the third embodiment. [Figure 15] FIG. 10 is an exploded perspective view illustrating the shaft configuration and the amount of light output of the fourth embodiment. [Figure 16] FIG. 10 is an exploded perspective view illustrating the shaft configuration and light output amount of Comparative Example 1. [Figure 17] FIG. 10 is an exploded perspective view illustrating the shaft configuration and light output amount of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described in more detail below with reference to the drawings, showing embodiments, but the present invention is not limited to these embodiments. In the following description, the same reference numerals will be used in different drawings to designate the same parts or parts having similar functions, and repeated description will be omitted. The various aspects of the present invention may be combined as appropriate within the scope of the present invention.

[0022] In this specification, "two directions are orthogonal" means that the angle between the two directions is preferably within a range of 90°±3°, more preferably within a range of 90°±1°, and even more preferably within a range of 90°±0.5°. "two directions are parallel" means that the angle between the two directions is preferably within a range of 0°±3°, more preferably within a range of 0°±1°, and even more preferably within a range of 0°±0.5°. "two directions form an angle of approximately 45°" means that the angle between the two directions is preferably within a range of 45°±3°, more preferably within a range of 45°±1°, and even more preferably within a range of 45°±0.5°.

[0023] In this specification, the term "observer side" refers to the side from which the observer views the mirror display, and is also referred to as the "front side." The term "rear side" refers to the side opposite the observer side.

[0024] In this specification, the term "white screen" refers to a state in which the transmittance of light incident from the normal direction to the rear surface of the liquid crystal panel is maximum, and the term "black screen" refers to a state in which the transmittance of light incident from the normal direction to the rear surface of the liquid crystal panel is minimum. For example, in a normally black liquid crystal panel, the screen becomes black when no voltage is applied to the liquid crystal layer and becomes white when voltage is applied to the liquid crystal layer. In a normally white liquid crystal panel, the screen becomes black when voltage is applied to the liquid crystal layer and becomes white when voltage is not applied to the liquid crystal layer. Note that the above-mentioned "no voltage application" also includes the case in which a voltage below the threshold value of the liquid crystal molecules is applied to the liquid crystal layer.

[0025] <Embodiment 1> 1 is a cross-sectional view of a mirror display according to an embodiment. The mirror display 1 according to the embodiment includes a liquid crystal panel 100, a reflective polarizer 200 disposed on the front side of the liquid crystal panel 100, and a backlight 300 disposed on the rear side of the liquid crystal panel 100.

[0026] The mirror display 1 has a reference direction that is perpendicular to the display surface of the mirror display when the display surface is vertically erected and that includes the left-right direction of the display surface. FIG. 2 is an explanatory diagram illustrating the reference plane of the mirror display. As shown in FIG. 2, when the mirror display is erected so that the display surface is perpendicular to the ground, the vertical direction is the y-axis, and the direction perpendicular to the y-axis on the display surface of the mirror display is the x-axis. The x-axis direction is also referred to as the left-right direction. The plane perpendicular to the x-axis and y-axis is the reference plane, and the reference plane is horizontal to the ground. FIG. 3 is a front view of a mirror display according to an embodiment placed horizontally. FIG. 4 is a front view of a mirror display according to an embodiment placed vertically. FIG. 1 is a schematic cross-sectional view taken along line X1-X2 of FIGS. 3 and 4. As shown in FIG. 3, when the mirror display is placed horizontally, the left-right direction is the longitudinal direction of the mirror display. As shown in FIG. 4, when the mirror display is placed vertically, the left-right direction is the lateral direction of the mirror display. In this specification, when viewed from the front side, the right-hand direction of the mirror display along the left-right direction is defined as the 0° orientation, and the left-hand direction is defined as the 180° orientation, and the left-right direction is also referred to as the 0°-180° orientation. Also, the orientation perpendicular to the 0°-180° orientation in the in-plane direction of the mirror display is also referred to as the 90°-270° orientation.

[0027] The mirror display of the embodiment is configured so that, when the backlight is turned on, a user positioned in the normal direction to the display surface of the mirror display can see their own mirror image, and a user positioned at 30°≦θ1≦60° to the display surface of the mirror display can see the image output from the display panel.

[0028] FIG. 5 is a schematic diagram of a mirror display seen from above, illustrating the mirror function, signage function, and anti-peeping effect. As shown in FIG. 5, user A, who desires the mirror function, observes the mirror display from a close distance at point P1 in the normal direction. The backlight used in the embodiment has low brightness when observed from the normal direction, and a reflective polarizer is disposed on the front side of the mirror display. Therefore, even when the liquid crystal panel is a white screen, user A can barely see the light emitted from the backlight (hereinafter referred to as backlight light), but can see his or her own mirror image at point P1 due to reflection of external light.

[0029] On the other hand, the backlight used in the embodiment has high brightness when viewed from an oblique direction, so the amount of light emitted from the mirror display in the oblique direction is large. Therefore, user B (see FIG. 5) viewing the mirror display from an oblique direction can see the display image, such as an advertisement, displayed on the liquid crystal panel. Note that the display image, such as the advertisement, is displayed as a white screen in which the light emitted from the backlight passes through the liquid crystal panel.

[0030] As shown in FIG. 5, when there is a point P2 where the angle θB between user B and the surface of the mirror display and the angle θA between user A and the surface of the mirror display are equal, in a conventional mirror display, user B can see a mirror image of user A at point P2, allowing user B to peek at user A. Conventionally, to achieve the mirror function, a black screen is sometimes displayed over a predetermined area in front of user A, making it particularly susceptible to peeking when point P2 is a black screen. The backlight used in the embodiment has high brightness when viewed from an oblique direction, causing some backlight light to leak toward the viewer, preventing the mirror effect. Therefore, even when the LCD panel is displayed as a black screen at point P2, the peeping prevention effect can be achieved.

[0031] (LCD panel) 1, the liquid crystal panel 100 may include a pair of substrates 10 and 20, and a liquid crystal layer 30 sandwiched between the pair of substrates 10 and 20. The pair of substrates may be a color filter (CF) substrate 10 having a color filter, and a TFT substrate 20 having switching elements such as a plurality of thin film transistors (TFTs).

[0032] The color filter substrate 10 may have, for example, color filters and a black matrix that separates the color filters. The TFT substrate 20 may have gate wiring and source wiring that intersects with the gate wiring, with TFTs disposed near the intersections of the gate wiring and source wiring, and pixel electrodes electrically connected to the TFTs.

[0033] Examples of liquid crystal panels include VA (Vertical Alignment) mode, FFS (Fringe Field Switching) mode, IPS (In-Plane-Switching) mode, and TN (Twisted Nematic) mode liquid crystal panels.

[0034] In the VA mode, a counter electrode may be disposed on the CF substrate side, and the liquid crystal molecules in the liquid crystal layer may be aligned approximately perpendicular to the substrate surface when no voltage is applied to the liquid crystal layer. In the FFS and IPS modes, a counter electrode may be disposed on the TFT substrate side, and the liquid crystal molecules in the liquid crystal layer may be aligned approximately horizontally to the substrate surface when no voltage is applied. In the TN mode, a counter electrode may be disposed on the CF substrate side, and the liquid crystal molecules in the liquid crystal layer may be aligned in a helical shape by rubbing treatment or the like, twisting from the TFT substrate toward the CF substrate. The amount of light transmission is controlled by changing the alignment of the liquid crystal molecules in response to the electric field generated in the liquid crystal layer 30 by the voltage applied between the pixel electrode and the counter electrode.

[0035] Horizontally aligned LCD panels such as FFS and IPS modes have a wide viewing angle in the diagonal direction, so using these LCD panels makes the mirror display brighter when viewed from an oblique direction, which is preferable in that it provides good signage performance.

[0036] (reflective polarizer) The reflective polarizer has a transmission axis that transmits light vibrating in a specific direction and a reflection axis that reflects light vibrating in a direction perpendicular to the transmission axis. The reflective polarizer is placed on the front side of the liquid crystal panel to reflect external light. An example of the reflective polarizer is the "DBEF-core" manufactured by 3M. Half mirrors such as metal vapor deposition films do not have optical axes such as a transmission axis and a reflection axis, so they cannot be arranged in a crossed Nicol configuration with the first and / or second linear polarizers. Therefore, when the backlight is turned on, the amount of light emitted in the normal direction cannot be reduced, and the display surface cannot be made black.

[0037] (linear polarizer) As shown in FIG. 1, the mirror display 1 may have a first linear polarizer 110 between the liquid crystal panel 100 and the reflective polarizer 200, and a second linear polarizer 120 between the liquid crystal panel 100 and the backlight 300.

[0038] The first and second linear polarizers are polarizers that transmit light vibrating in a specific direction. The first and second linear polarizers are preferably absorption-type linear polarizers having a transmission axis that transmits light vibrating in a specific direction and an absorption axis that is perpendicular to the transmission axis. The first and second linear polarizers are preferably arranged so that their transmission axes are perpendicular to each other. As the first and second linear polarizers, known polarizing plates can be used, such as Nitto Denko's "TEG1465DU."

[0039] The degree of polarization of the first and second linear polarizers and half mirrors (reflective polarizers) is preferably high. The degree of polarization of a polarizer is calculated according to the following formula (1): Two polarizers for which the degree of polarization is to be measured are prepared, and the light transmittance (H11) is measured at a wavelength λ when the polarizers are stacked so that their transmission axes are in the same direction, and the light transmittance (H1) is measured at a wavelength λ when the two polarizers are stacked so that their transmission axes are perpendicular to each other. The degree of polarization is preferably 99.5% or more, and particularly preferably 99.8% or more. Polarization degree [(H11-H1) / (H11+H1)]1 / 2 (1)

[0040] The absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer may be perpendicular to each other. This configuration can further reduce the amount of white light emitted in the normal direction, thereby enhancing the mirror function. The mirror function refers to the ability of the mirror display to allow a user positioned in the normal direction of the display surface to see their own mirror image.

[0041] The absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer may be parallel. This configuration increases the amount of light emitted from the white screen in oblique directions, further enhancing the signage function. The signage function refers to the ability to allow a user positioned at an angle of 30°≦θ1≦60° relative to the display surface of the mirror display to view an image output from the display panel.

[0042] Either the absorption axis of the first linear polarizer or the absorption axis of the second linear polarizer may be parallel to or perpendicular to the left-right direction.

[0043] From the viewpoint of enhancing the signage function, it is preferable that at least one of the absorption axes of the first linear polarizer and the second linear polarizer forms an angle of approximately 45° with the left-right direction. It is more preferable that the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer are orthogonal to each other, and that both the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer form an angle of approximately 45° with the left-right direction.

[0044] From the viewpoint of achieving a balanced enhancement of the mirror function in the normal direction, the signage function, and the anti-peeping function, it is preferable that at least one of the absorption axes of the first linear polarizer and the second linear polarizer forms an angle of approximately 45° with the left-right direction, that the absorption axis of the second linear polarizer and the absorption axis of the first linear polarizer are orthogonal to each other, and that the absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer are orthogonal to each other. When the reflection axis of the reflective polarizer, the absorption axis of the first linear polarizer, and the absorption axis of the second linear polarizer are arranged so as to be orthogonal to each other, backlight light in the normal direction is almost completely blocked. On the other hand, when viewed from an oblique direction, a large amount of light leaks in an orientation of 45° with respect to the reflection axis and / or absorption axis. Therefore, by aligning the left-right direction, in which the brightness of the backlight 300 is high, with the orientation in which the light leaks, the amount of light emitted in the oblique direction can be increased, thereby improving the signage function.

[0045] (backlight) FIG. 6 is a cross-sectional schematic diagram of a backlight illustrating the intensity of emitted light. As shown in FIG. 6, if the angle θ1 is a direction along the reference plane relative to the normal direction of the display surface of the mirror display, the luminance L1 of the backlight 300 when observed from the normal direction of the display surface of the mirror display is lower than the luminance L2 when observed from a direction in which θ1 satisfies 30°≦θ1≦60°. The luminance L1 when observed from the normal direction of the backlight and the luminance L2 when observed from a direction in which θ1 satisfies 30°≦θ1≦60° can be measured using a spectroradiometer (e.g., an SR-LED manufactured by Topcon Technohouse Corporation). Specifically, a measuring device is placed in the normal direction to the light-emitting surface of the backlight (the surface facing the LCD panel), and the distance between the backlight and the measuring device is adjusted to 500 mm (for a measurement angle of 2°). When there is no particular distinction between an edge-lit backlight 300A and a direct-lit backlight 300B (described later), they are simply referred to as backlights 300.

[0046] It is sufficient that the luminance L2 of the backlight 300 when observed from at least one angle in the range of 30°≦θ1≦60° is higher than the luminance L1 when observed from the normal direction, and it is more preferable that the luminance L2 when observed from at least one angle in the range of 40°≦θ1≦50° is higher than the luminance L1 when observed from the normal direction. It is even more preferable that the luminance when observed from all angles in the range of 30°≦θ1≦60° is higher than the luminance L1 when observed from the normal direction, and it is particularly preferable that the luminance when observed from all angles in the range of 40°≦θ1≦50° is higher than the luminance L1 when observed from the normal direction. It is preferable that the backlight 300 has a maximum luminance when observed from a direction in which the θ1 is 30°≦θ1≦60°, and it is more preferable that the luminance is maximum when observed from a direction in which the θ1 is 40°≦θ1≦50°.

[0047] The backlight preferably has light-emitting elements arranged along a direction perpendicular to the left-right direction of the display surface, and a plurality of linear protrusions extending in a direction perpendicular to the left-right direction of the display surface and arranged along the left-right direction of the display surface, and each of the linear protrusions preferably has an inclined surface that slopes toward the left-right direction of the display surface. By having the linear protrusions have an inclined surface, light emitted from the light-emitting elements is strongly emitted in an oblique direction with respect to the reference plane, and the brightness when observed from an oblique direction can be made higher than the brightness when observed from a normal direction to the display surface of the mirror display.

[0048] The backlight may be an edge-lit backlight or a direct-lit backlight. In the case of an edge-lit backlight, the linear convex portion may be a groove formed on the surface of a light guide plate, a prism sheet, or the like. In the case of a direct-lit backlight, the linear convex portion may be a substrate on which a light-emitting element is disposed.

[0049] Fig. 7 is a cross-sectional view showing an example of an edge-lit backlight. Fig. 8 is a plan view showing the backlight shown in Fig. 7. Fig. 7 is a cross-sectional view taken along line X3-X4 in the 0°-180° direction in Fig. 8. As shown in Fig. 7, backlight 300A may have light-emitting elements 301, a light guide plate 302, and a prism sheet 303 arranged on the front side of light guide plate 302. These components may be housed in housing 306.

[0050] The light emitting elements 301 may be arranged along a direction perpendicular to the left-right direction of the display surface in a plan view. The light emitting elements 301 may be arranged on the side of an end of the light guide plate 302. The light emitting elements 301 may be arranged at one of the end of the light guide plate 302 at the 0° orientation and the end of the light guide plate 302 at the 180° orientation, or may be arranged at both ends. As the light emitting elements 301, those known in the field of backlights can be used, and examples thereof include light emitting diodes (LEDs).

[0051] Light guide plate 302 has an incident surface (the side surface of the end portion) onto which light emitted from light emitting element 301 is incident, and an exit surface orthogonal to the incident surface. The surface of light guide plate 302 facing the liquid crystal panel may be provided with irregularities, grooves, textured finish, or the like in order to cause the light incident from the incident surface to exit toward the viewer.

[0052] 7, prism sheet 303 may have a plurality of linear prism structures 303a as the plurality of linear convex portions. It is preferable that the plurality of linear prism structures 303a protrude toward light guide plate 302. The surface of prism sheet 303 facing light guide plate 302 is an incident surface onto which light emitted from light guide plate 302 is incident, and the surface opposite to the incident surface is a light output surface.

[0053] As shown in Fig. 8, it is preferable that the prism structure 303a extends in a direction perpendicular to the left-right direction of the display surface in a plan view. Alternatively, the prism structure 303a may be arranged along the left-right direction of the display surface in a plan view. When the plurality of light-emitting elements 301 are arranged along the 90°-270° direction, the prism structure 303a may be arranged along the 0°-180° direction. In Fig. 8, the sides (peaks) protruding toward the light guide plate 302 side are indicated by dotted lines, and the sides (valleys) protruding toward the liquid crystal panel side are indicated by dashed-dotted lines.

[0054] The shape of the prism structure 303a may be, for example, a triangular prism, as long as it has an inclined surface that slopes in the left-right direction of the display screen. As shown in FIG. 7, the prism structure 303a may have a first inclined surface 303b that slopes toward a 0° azimuth and a second inclined surface 303c that slopes toward a 180° azimuth with respect to the normal direction. Let θ2 be the angle of the first inclined surface 303b with respect to a plane parallel to the light-emitting surface of the prism sheet 303, and θ3 be the angle of the second inclined surface 303c with respect to the plane parallel to the light-emitting surface of the prism sheet 303. By adjusting the width of the prism structure 303a and the angles θ2 and θ3, the luminance of the backlight 300A when viewed from the normal direction can be made lower than the luminance when viewed from a direction satisfying the relationship 30°≦θ1≦60°.

[0055] The prism sheet 303 may be made of glass or transparent resin such as polycarbonate, polymethyl methacrylate, or polyester.

[0056] The backlight 300A may further include a light-reflecting layer 304 on the rear side of the light guide plate 302. The light-reflecting layer 304 may be a layer commonly used in the field of backlights, and may be, for example, a metal vapor deposition film.

[0057] To reduce the hot spot phenomenon in which parts of the display surface become locally bright, backlight 300A may further include light diffusion layer 305 on the front side of prism sheet 303. Examples of light diffusion layer 305 include inorganic powders such as calcium carbonate powder, titanium oxide powder, zinc oxide, alumina powder, silica powder, and clay; and resin layers containing light-diffusing materials such as glass beads and glass fibers. Light diffusion layer 305 may include a support such as a transparent film.

[0058] Fig. 9 is a cross-sectional view showing an example of a direct-type backlight. Fig. 10 is a plan view showing the backlight shown in Fig. 9. Fig. 9 is a cross-sectional view taken along line X5-X6 in the 0°-180° direction in Fig. 10. In Fig. 10, the sides protruding toward the rear surface are indicated by dotted lines, and the sides protruding toward the liquid crystal panel are indicated by dashed lines. As shown in Fig. 9, the backlight 300B may have mountain-shaped protrusions 303a as a plurality of linear protrusions.

[0059] 9, the substrate 307 may have a third inclined surface 307a inclined toward the 0° azimuth with respect to the normal direction and a fourth inclined surface 307b inclined toward the 180° azimuth. The third inclined surface 307a and the fourth inclined surface 307b are preferably arranged alternately along the 0°-180° azimuth.

[0060] The angle θ4 formed between the third inclined surface 307a and the fourth inclined surface 307b is, for example, preferably 30° or more and 60° or less, and more preferably 40° or more and 50° or less.

[0061] As shown in FIG. 10, the convex portion 303a preferably extends in a direction perpendicular to the left-right direction of the display surface in a plan view. As shown in FIG. 10, the direct-type backlight 300B may have a plurality of light-emitting elements 301 arranged in a matrix in a plan view. It is preferable that the plurality of light-emitting elements 301 are arranged along the extension direction of the convex portion 303a on each of the third inclined surface 307a and the fourth inclined surface 307b. By arranging the light-emitting elements 301 on the third inclined surface 307a and the fourth inclined surface 307b, as shown in FIG. 9, the light-emitting elements 301 can be oriented obliquely, and the luminance when viewed obliquely in the left-right direction of the display surface can be higher than the luminance when viewed from the normal direction.

[0062] The base material 307 may be a housing that forms the bottom of the backlight. The base material 307 may be made of metal or resin. If the base material 307 is made of resin, it may have a light-reflecting layer such as a metal vapor deposition film on the surface on which the light-emitting element 301 is disposed.

[0063] The backlight 300B may further include a light diffusion layer 305 on the front side of the light emitting element 301.

[0064] From the viewpoint of improving the anti-peeping function, it is preferable that the mirror display does not include a retardation compensation layer. If the mirror display includes a retardation compensation layer, the black screen will block light from oblique directions, which may reduce the anti-peeping function. [Example]

[0065] The effects of the present invention will be explained below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0066] In the following examples and comparative examples, the axial arrangement between the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer was set to Condition 1 or 2 in Table 1 below, and the axial arrangement between the reflection axis of the reflective polarizer and the absorption axis of the first linear polarizer was set to one of Conditions 3 to 6 in Table 2 below. The direction horizontal to the ground (left-right direction) when the display surface of the mirror display is set upright was defined as the 0°-180° azimuth. The light output ratio in Table 1 below was calculated by setting the brightness (nit) of a white screen in the normal direction (θ1=0°) under Condition 1 to 100. The light output amount in Table 2 below was calculated by setting the brightness (nit) in the normal direction (θ1=0°) under Condition 3 to 100.

[0067] [Table 1]

[0068] [Table 2]

[0069] Example 1 As shown in Figure 1, the mirror display of Example 1 was configured to include a reflective polarizer 200, a liquid crystal panel 100, and a backlight 300 in this order, with a first linear polarizer 110 between the liquid crystal panel 100 and the reflective polarizer 200, and a second linear polarizer 120 between the liquid crystal panel 100 and the backlight 300.

[0070] FIG. 11 is a graph showing the light output intensity of the backlight used in the example and the backlight used in the comparative example. The light output intensity shown on the vertical axis in FIG. 11 is the relative brightness, with the highest brightness being 1 for the backlight used in the example and the backlight used in the comparative example. FIG. 11 shows the brightness when the angle of θ1 is changed from the normal direction (θ1 = 0°) to the front surface of the backlight (θ1 = 90°) along the left-right direction (0°-180° azimuth). A typical backlight, like the backlight used in the comparative example in FIG. 11, is configured so that the brightness is highest when observed from the normal direction. On the other hand, the backlight used in the example is configured so that the brightness is low when observed from the normal direction and high when observed from an oblique direction (30°≦θ1≦60°). The backlight used in the example in FIG. 11 illustrates a case where the brightness is highest at θ1 = 45° and lowest in the normal direction.

[0071] Fig. 12 is an exploded perspective view illustrating the axis configuration and light output amount of Example 1. The axis configurations of the reflective polarizer 200, the first linear polarizer 110, and the second linear polarizer 120 were arranged as shown in Fig. 12 and Table 3 below. In Fig. 12 to Fig. 17 described below, the solid double-headed arrows of the first linear polarizer 110 and the second linear polarizer 120 indicate the direction of the absorption axis, and the solid double-headed arrow of the reflective polarizer 200 indicates the direction of the reflection axis. The dotted double-headed arrows of the first linear polarizer 110, the second linear polarizer 120, and the reflective polarizer 200 indicate the direction of the transmission axis.

[0072] Examples 2 to 4 13 to 15 are exploded perspective views illustrating the axial configurations and light output amounts of Examples 2 to 4. The axial configurations of the reflective polarizer 200, the first linear polarizer 110, and the second linear polarizer 120 were as shown in Figs. 13 to 15 and Table 3 below, but the configurations were the same as in Example 1.

[0073] (Comparative Examples 1 and 2) 16 and 17 are exploded perspective views illustrating the axial configurations and light output amounts of Comparative Examples 1 and 2, respectively. In Comparative Examples 1 and 2, a simulation was performed using a backlight in which the luminance when observed from the normal direction shown in FIG. 11 was higher than the luminance when observed from an oblique direction. The configurations were the same as in Example 1, except that the axial configurations of the reflective polarizer 200, the first linear polarizer 110, and the second linear polarizer 120 were as shown in FIGS. 16 and 17 and Table 3 below.

[0074] <Evaluation test> With the backlight turned on, the liquid crystal panels of the Examples and Comparative Examples were set to a white screen and a black screen, and the luminance when observed from the normal direction (θ1=0°) to the reference plane of the mirror displays of the Examples and Comparative Examples and the luminance when observed from an oblique direction (θ1=45°) to the reference plane were simulated, and the results are shown in Table 3 below. Note that for Examples 1 to 4, the luminance when observed from the normal direction to the backlight was set to 10 and the luminance when observed from θ1=45° was set to 100, and for Comparative Examples 1 and 2, the luminance when observed from the normal direction to the backlight was set to 100 and the luminance when observed from θ1=45° was set to 50 based on the graph in Fig. 11, and the product of the transmittance was calculated.

[0075] (Mirror function) The light output rates of the white screen and black screen in the normal direction obtained above were evaluated according to the following evaluation criteria. The lower the light output rate in the normal direction, the higher the performance as a mirror. ◎: Normal direction light output rate is less than 3 〇: Normal direction light output ratio is 3 or more and less than 10 △: Normal direction light output rate is 10 or more and less than 30 ×: Normal direction light output ratio is 30 or more

[0076] (Signage function) The light output rate of the white screen in the oblique direction obtained above was evaluated according to the following evaluation criteria. It can be said that the higher the light output rate of the white screen in the oblique direction, the higher the performance as signage. ◎: White screen luminance output in diagonal directions is over 70 〇: The light output rate of the white screen in the diagonal direction is over 30 and 70 or less △: The light output rate of the white screen in the diagonal direction is over 10 and 30 or less ×: The light output rate of the white screen in the diagonal direction is 10 or less

[0077] (Anti-peeping function) The light output rate of the black screen in the oblique direction obtained above was evaluated according to the following evaluation criteria. The higher the light output rate of the black screen in the oblique direction, the higher the anti-peeping function. ◎: The light output rate of the black screen in the diagonal direction is 20 or more ○: The light output rate of the black screen in the diagonal direction is 10 or more and less than 20 △: The light output rate of the black screen in the diagonal direction is 5 or more and less than 10 ×: The light output rate of the black screen in the diagonal direction is less than 5

[0078] [Table 3]

[0079] Comparative Examples 1 and 2, which used backlights in which the luminance when viewed from the normal direction was higher than the luminance when viewed from an oblique direction, had a high light output rate on a white screen in the normal direction and poor mirror function. In particular, Comparative Example 1 had a light output rate of 100 on a white screen in the normal direction, and did not function as a mirror. In Examples 1 to 4, the light output rates on both the white screen and black screen in the normal direction were kept within about 10, and it was confirmed that they functioned as a mirror whether the screen was a white screen or a black screen. Furthermore, in Examples 1 to 4, the light output rate on a white screen in an oblique direction was 50 to 100, and it was confirmed that they had sufficient signage function.

[0080] In particular, in Example 3, the absorption axis of the second linear polarizer was arranged at an angle of 45° with respect to the left-right direction in which the backlight 300 has the maximum brightness, the reflective axis of the reflective polarizer and the absorption axis of the first linear polarizer were arranged so as to be perpendicular to each other, and the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer were arranged so as to be perpendicular to each other, and thus the output rate of the white screen in the normal direction was suppressed to about 3, thereby providing a deep black mirror function, and the output rate of the white screen in an oblique direction was 70, thereby providing an efficient signage function. Furthermore, some black floating was observed on the black screen in an oblique direction, resulting in improved anti-peeping function. [Explanation of symbols]

[0081] 1: Mirror display 10: Substrate (color filter substrate) 20: Substrate (TFT substrate) 30: Liquid crystal layer 100: LCD panel 110: First linear polarizer 120: Second linear polarizer 200: Reflective polarizer 300, 300A, 300B, 1300: Backlight 301: Light emitting element 302: Light guide plate 303: Prism sheet 303a: Convex portion (prism structure) 303b: First inclined plane 303c: Second inclined surface 304: Light reflective layer 305: Light diffusion layer 306: Cabinet 307: Convex 307: Base material 307a: Third Inclined Plane 307b: Fourth Inclined Plane

Claims

1. A mirror display comprising a liquid crystal panel, a reflective polarizer disposed on the front side of the liquid crystal panel, and a backlight disposed on the rear side of the liquid crystal panel, When the display surface of the mirror display is set upright, a plane that is perpendicular to the display surface and includes the left and right directions of the display surface is defined as a reference plane. A mirror display in which the brightness of the backlight when observed from the normal direction of the display surface is lower than the brightness when observed from a direction along the reference plane at an angle of 30° or more and 60° or less with respect to the normal direction of the display surface.

2. When the backlight is turned on, The mirror display of claim 1, configured to allow a user positioned in the normal direction of the display surface of the mirror display to view their own mirror image, and to allow a user observing from a direction along the reference plane at an angle of 30° or more and 60° or less with respect to the normal direction of the display surface to view the image output from the display panel.

3. 2. The mirror display of claim 1, further comprising a first linear polarizer between the liquid crystal panel and the reflective polarizer, and a second linear polarizer between the liquid crystal panel and the backlight.

4. The mirror display of claim 3 , wherein the absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer are orthogonal to each other.

5. The mirror display of claim 3 , wherein the absorption axis of the first linear polarizer and the reflection axis of the reflective polarizer are parallel.

6. A mirror display as described in claim 4 or 5, wherein either the absorption axis of the first linear polarizer or the absorption axis of the second linear polarizer is parallel to or perpendicular to the left-right direction of the display surface.

7. A mirror display as described in claim 4 or 5, wherein at least one of the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer forms an angle of approximately 45° with the left-right direction of the display surface.

8. At least one of the absorption axis of the first linear polarizer and the absorption axis of the second linear polarizer is The angle is approximately 45° with respect to the left and right direction of the display surface, The mirror display of claim 3, wherein the absorption axis of the second linear polarizer is perpendicular to the absorption axis of the first linear polarizer, and the absorption axis of the first linear polarizer is perpendicular to the reflection axis of the reflective polarizer.

9. the backlight has light-emitting elements arranged along a direction perpendicular to the left-right direction of the display surface, and a plurality of linear convex portions arranged along the left-right direction of the display surface and extending in the direction perpendicular to the left-right direction of the display surface, The mirror display according to claim 1 , wherein each of the plurality of linear convex portions has an inclined surface that slopes in the left-right direction of the display surface.

Images