Privacy display device

Abstract

This invention discloses a privacy display device, comprising a display panel stacked in layers and a viewing angle control module. The viewing angle control module includes a first polarizing layer, a first liquid crystal layer, a second polarizing layer, a second liquid crystal layer, and a third polarizing layer stacked in sequence. The phase delay of the first liquid crystal layer and the second liquid crystal layer falls within the range of 700nm to 1200nm.

Description

Technical Field

[0001] This invention relates to a display device, and more particularly to a display device with a privacy protection function. Background Technology

[0002] Generally, display devices are designed for wide viewing angles to allow multiple viewers to watch simultaneously. However, in certain situations or occasions, it is necessary to restrict the viewing direction. For example, the demand for in-vehicle privacy screens has been increasing in recent years, primarily due to the desire to shield the driver's view (i.e., driver's side privacy) while the front passenger enjoys the audio-visual equipment, thus avoiding any impact on driving safety. In other words, an asymmetrical viewing angle is required. Furthermore, when there are no driving safety concerns, it is desirable for both the driver and front passenger to be able to view the screen simultaneously. However, existing privacy switching technologies on the market all offer symmetrical viewing angles and cannot limit brightness for specific viewing angles. Summary of the Invention

[0003] This invention provides a privacy display device with good privacy protection capabilities.

[0004] According to an embodiment of the present invention, a privacy display device is provided, including a display panel and a viewing angle control module. The viewing angle control module includes a first polarizing layer, a first liquid crystal layer, a second polarizing layer, a second liquid crystal layer, and a third polarizing layer stacked sequentially, wherein the phase delays of the first liquid crystal layer and the second liquid crystal layer fall within the range of 700 nm to 1200 nm. The viewing angle control module has a first side adjacent to the first polarizing layer and a second side adjacent to the third polarizing layer, and the display panel is disposed on the first side of the viewing angle control module or on the second side of the viewing angle control module.

[0005] Based on the above, the privacy display device provided in this embodiment of the invention utilizes a dual TN liquid crystal structure to provide excellent privacy capabilities. Furthermore, the phase retardation of the dual TN liquid crystal layers falls within the range of 700nm to 1200nm, ensuring that the brightness and color saturation at the viewing angle do not exhibit significant differences between privacy mode and sharing mode.

[0006] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0007] Figure 1 A schematic diagram illustrating a privacy display device according to an embodiment of the present invention is shown.

[0008] Figure 2 A schematic diagram illustrating a privacy display device according to an embodiment of the present invention is shown.

[0009] Figure 3 A graph showing the relationship between the phase delay and light transmittance of a liquid crystal layer is plotted.

[0010] Figure 4 A schematic diagram illustrating a view control module according to an embodiment of the present invention is shown.

[0011] Figure 5 A schematic diagram illustrating a privacy display device according to an embodiment of the present invention is shown.

[0012] Figure 6 A schematic diagram illustrating a privacy display device according to an embodiment of the present invention is shown.

[0013] In the attached figures, the following labels are used:

[0014] 100, 200, 300, 400, 500, 600: Privacy display devices

[0015] 101, 201: Display Panel

[0016] 102, 402: View Control Module

[0017] 103: Quarter-wave plate

[0018] D1: First alignment direction

[0019] D2: Second alignment direction

[0020] D3: Third alignment direction

[0021] D4: Fourth alignment direction

[0022] LC1: First liquid crystal layer

[0023] LC2: Second liquid crystal layer

[0024] P1: First polarizing layer

[0025] P2: Second polarizing layer

[0026] P3: Third polarizing layer

[0027] P4: Fourth polarizing layer

[0028] S1: First side

[0029] S2: Second side

[0030] T1: First Penetration Direction

[0031] T2: Second Penetration Direction

[0032] T3: Third Penetration Direction

[0033] X, Y, Z: Direction Detailed Implementation

[0034] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0035] Reference Figure 1 The illustration depicts a privacy display device according to an embodiment of the present invention. The privacy display device 100 includes a display panel 101, a viewing angle control module 102, and a quarter-wave plate 103. The viewing angle control module 102 includes a first polarizing layer P1, a first liquid crystal layer LC1, a second polarizing layer P2, a second liquid crystal layer LC2, and a third polarizing layer P3 arranged sequentially, wherein the liquid crystal molecules in the first liquid crystal layer LC1 and the second liquid crystal layer LC2 are twisted nematic liquid crystals (TN liquid crystals).

[0036] It should be noted that the privacy display device 100 is placed on the XY plane, where the +X direction has an azimuth angle of 0 degrees, the +Y direction has an azimuth angle of 90 degrees, the -X direction has an azimuth angle of 180 degrees, and the -Y direction has an azimuth angle of 270 degrees. The +Z direction has a viewing angle of 0 degrees, i.e., the orthogonal viewing angle direction.

[0037] It should be specifically noted that the embodiments of the present invention utilize the grayscale viewing angle asymmetry of the TN liquid crystal in the viewing angle control module during driving to achieve a viewing angle asymmetry display mode (hereinafter referred to as privacy mode). Furthermore, when the TN liquid crystal is not driven, the display mode reverts to a viewing angle symmetrical sharing mode.

[0038] In some embodiments of the present invention, the phase retardations of both the first liquid crystal layer LC1 and the second liquid crystal layer LC2 fall within the range of 700nm to 1200nm, in order to maintain brightness at a positive viewing angle and avoid excessive brightness attenuation when switching to privacy mode. Specifically, please refer to... Figure 3 And Table 1, to understand the effect of the phase retardation of the TN liquid crystal layer of the viewing angle control module 102 on the transmitted light brightness and chromaticity, wherein Figure 3 This is a graph showing the relationship between the phase retardation of the liquid crystal layer and the transmittance of different colors of light. In the comparative examples shown in Table 1, the phase retardation of the TN liquid crystal layer is 477 nm, corresponding to the first-order maximum transmittance at 550 nm in the green light band. In the first embodiment of the present invention shown in Table 1, the phase retardation of the TN liquid crystal layer is 872 nm, corresponding to the second-order maximum transmittance at 450 nm in the blue light band. In the second embodiment of the present invention shown in Table 1, the phase retardation of the TN liquid crystal layer is 1066 nm, corresponding to the second-order maximum transmittance at 550 nm in the green light band. Table 1 lists the x-values ​​and y-values ​​of the viewing angle in the sharing mode and the privacy mode in the above comparative examples and the first and second embodiments of the present invention.

[0039] Table 1:

[0040]

[0041] As shown in Table 1, the display device in the comparative example has a viewing angle brightness of 127.3 nits in privacy mode, which is significantly lower than the 241.2 nits in sharing mode. In contrast, the first embodiment of the present invention has a viewing angle brightness of 204.6 nits in privacy mode, which is only slightly lower than the 217.2 nits in sharing mode. The second embodiment of the present invention has a viewing angle brightness of 200.4 nits in privacy mode, which is only slightly lower than the 241.0 nits in sharing mode.

[0042] In addition, as shown in Table 1, the color difference of the comparative example in the forward viewing angle between sharing mode and privacy mode is Δ(x,y) = (0.064, 0.086). In contrast, the color difference of the first embodiment of the present invention in the sharing mode and privacy mode is Δ(x,y) = (0.007, 0.010), and the color difference of the second embodiment of the present invention in the sharing mode and privacy mode is Δ(x,y) = (0.018, 0.018). That is to say, compared to the comparative example, in the first and second embodiments of the present invention, the color difference of the forward viewing angle between sharing mode and privacy mode is smaller, and the display device has better color performance.

[0043] Therefore, according to some embodiments of the present invention, the phase retardation of both the first liquid crystal layer LC1 and the second liquid crystal layer LC2 is configured within the range of 872nm ± 100nm. According to some embodiments of the present invention, the phase retardation of both the first liquid crystal layer LC1 and the second liquid crystal layer LC2 is configured within the range of 1066nm ± 100nm, resulting in good brightness and color performance at the forward viewing angle. Furthermore, the TN liquid crystal layer with the aforementioned phase retardation also meets the requirement that the brightness at a side viewing angle of 45 degrees is less than 1% of the brightness at the forward viewing angle.

[0044] Please refer to the above again. Figure 1 The viewing angle control module 102 has a first side S1 near the first polarizing layer P1 and a second side S2 near the third polarizing layer P3. In this embodiment, the display panel 101 is disposed on the first side S1 of the viewing angle control module 102, that is, the display panel 101 is disposed below the viewing angle control module 102, and the quarter-wave plate 103 is sandwiched between the display panel 101 and the viewing angle control module 102.

[0045] The first polarizing layer P1 has a first transmission direction T1, the first liquid crystal layer LC1 has a first alignment direction D1 and a second alignment direction D2, the second polarizing layer P2 has a second transmission direction T2, the second liquid crystal layer LC2 has a third alignment direction D3 and a fourth alignment direction D4, and the third polarizing layer P3 has a third transmission direction T3. In this embodiment, the second transmission direction T2 is perpendicular to the first transmission direction T1 and the third transmission direction T3. The orientation of the first alignment direction D1, the second alignment direction D2, the third alignment direction D3, and the fourth alignment direction D4 can be defined by configuring multiple alignment layers (not shown). The first alignment direction D1 and the second alignment direction D2 enable the liquid crystal molecules of the first liquid crystal layer LC1 to achieve a good rotation effect. Similarly, the third alignment direction D3 and the fourth alignment direction D4 enable the liquid crystal molecules of the second liquid crystal layer LC2 to achieve a good rotation effect.

[0046] exist Figure 1 In the illustrated embodiment, the display panel 101 is a self-emissive display panel, such as an organic light-emitting diode (OLED) display panel or a micro-LED display panel. A quarter-wave plate 103 is disposed between the self-emissive display panel 101 and the viewing angle control module 102. The slow axis of the quarter-wave plate 103 is parallel to the Y direction (i.e., it has a 90-degree azimuth angle) and is angled at 45 degrees to the first penetration direction T1. Accordingly, when ambient light passes through the viewing angle control module 102, the linearly polarized light passing downward through the first polarizing layer P1 will be formed into left-handed / right-handed light after passing through the quarter-wave plate 103. This left-handed / right-handed light is reflected by the metal structure within the self-emissive display panel 101 and then becomes right-handed / left-handed light. After passing upward through the quarter-wave plate 103, it becomes linearly polarized light perpendicular to the first penetration direction T1 and is thus blocked by the first polarizing layer P1. In other words, by configuring the quarter-wave plate 103 sandwiched between the self-emissive display panel 101 and the viewing angle control module 102, ambient light reflection can be effectively avoided.

[0047] In this embodiment, the liquid crystal molecules in the first liquid crystal layer LC1 and the second liquid crystal layer LC2 are TN liquid crystals. The privacy display device 100 utilizes the grayscale viewing angle asymmetry of the TN liquid crystal during driving to achieve an asymmetrical viewing angle privacy mode. When the TN liquid crystal is not driven, the display mode of the privacy display device 100 reverts to a symmetrical viewing angle sharing mode.

[0048] Furthermore, since the emitted light from the self-emissive display panel 101 itself has no obvious polarization state, compared to the limitation imposed by the upper polarizer of a liquid crystal display panel on the viewing angle, the first penetration direction T1 in this embodiment is configured with an azimuth angle of 45 degrees. This significantly improves the privacy protection efficiency for the left viewing angle (i.e., 180-degree azimuth angle). However, this invention is not limited to the aforementioned left and right privacy protection. Specifically, since the emitted light from the self-emissive display panel 101 itself has no obvious polarization state, the privacy protection viewing angle is not limited to the aforementioned left and right viewing angles. Instead, the direction of the first penetration direction T1 can be changed as needed to have any azimuth angle, allowing for free variation of the privacy protection viewing angle.

[0049] exist Figure 1 In the illustrated embodiment, the first alignment direction D1 of the first liquid crystal layer LC1 is parallel to the third alignment direction D3 of the second liquid crystal layer LC2, and the second alignment direction D2 of the first liquid crystal layer LC1 is parallel to the fourth alignment direction D4 of the second liquid crystal layer LC2. The second transmission direction T2 is parallel to the second alignment direction D2 of the first liquid crystal layer LC1 and perpendicular to the third alignment direction D3 of the second liquid crystal layer LC2. The first polarizing layer P1 and the second polarizing layer P2 are attached to the first liquid crystal layer LC1 in E-mode, and the second polarizing layer P2 and the third polarizing layer P3 are attached to the second liquid crystal layer LC2 in O-mode.

[0050] To fully illustrate the various embodiments of the present invention, other embodiments will be described below. It must be noted that the following embodiments use the same element reference numerals and some content as those in the foregoing embodiments, with the same reference numerals representing the same or similar elements, and descriptions of identical technical content omitted. For explanations of the omitted parts, please refer to the foregoing embodiments; these will not be repeated in the following embodiments.

[0051] Please refer to the following. Figure 2 The illustration depicts a privacy display device according to an embodiment of the present invention. The privacy display device 200 includes a display panel 101, a viewing angle control module 102, and a quarter-wave plate 103. The viewing angle control module 102 includes a first polarizing layer P1, a first liquid crystal layer LC1, a second polarizing layer P2, a second liquid crystal layer LC2, and a third polarizing layer P3 arranged in sequence. The display panel 101 is disposed on a first side S1 of the viewing angle control module 102, but the present invention is not limited thereto; in some embodiments, the display panel 101 is disposed on a second side S2 of the viewing angle control module 102.

[0052] The privacy display device 200 of this embodiment differs from the privacy display device 100 in that the slow axis of the quarter-wave plate 103 is parallel to the X direction (with a 0-degree azimuth angle), and the first penetration direction T1 is configured with a 135-degree azimuth angle. Therefore, there is a 135-degree gap between the quarter-wave plate 103 and the first penetration direction T1. Accordingly, when ambient light passes through the viewing angle control module 102 of the privacy display device 200, the linearly polarized light passing downward through the first polarizing layer P1 will be formed as left-handed / right-handed light after passing through the quarter-wave plate 103. This left-handed / right-handed light is reflected by the metal structure in the self-emissive display panel 101 and formed as right-handed / left-handed light. After passing upward through the quarter-wave plate 103, it is formed as linearly polarized light perpendicular to the first penetration direction T1, and is therefore blocked by the first polarizing layer P1, thus preventing ambient light reflection.

[0053] Since the first penetration direction T1 has an azimuth angle of 135 degrees, the privacy protection efficiency of the left viewing angle (i.e., 180-degree azimuth angle) can be significantly improved. The privacy protection viewing angle of the privacy display device 200 is not limited to the aforementioned left and right privacy protection. Specifically, since the emitted light of the self-emissive display panel 101 itself has no obvious polarization state, the privacy protection viewing angle is not limited to the aforementioned left and right viewing angles. Instead, the direction of the first penetration direction T1 can be changed as needed to give it any azimuth angle, thus freely changing the privacy protection viewing angle.

[0054] exist Figure 2 In the illustrated embodiment, the second transmission direction T2 is perpendicular to the second alignment direction D2 of the first liquid crystal layer LC1 and parallel to the third alignment direction D3 of the second liquid crystal layer LC2. The second transmission direction T2 is perpendicular to the first transmission direction T1 and the third transmission direction T3. The first polarizing layer P1 and the second polarizing layer P2 are attached to the first liquid crystal layer LC1 in O-mode, and the second polarizing layer P2 and the third polarizing layer P3 are attached to the second liquid crystal layer LC2 in E-mode.

[0055] Reference Figure 4 The diagram illustrates a viewing angle control module according to an embodiment of the present invention. The viewing angle control module 402 includes a first polarizing layer P1, a first liquid crystal layer LC1, a second polarizing layer P2, a second liquid crystal layer LC2, and a third polarizing layer P3 arranged in sequence. The liquid crystal molecules in the first liquid crystal layer LC1 and the second liquid crystal layer LC2 are twisted nematic liquid crystals (TN liquid crystals). The third alignment direction D3 of the second liquid crystal layer LC2 is parallel to the second transmission direction T2, the fourth alignment direction D4 of the second liquid crystal layer LC2 is parallel to the third transmission direction T3, and the second alignment direction D2 of the first liquid crystal layer LC1 is not parallel to the second transmission direction T2.

[0056] Figure 4 The view control module 402 and Figure 1 as well as Figure 2 The same as the viewing angle control module 102 in the first liquid crystal layer LC1 is that the angle between the first alignment direction D1 and the second alignment direction D2 of the first liquid crystal layer LC1 is 90 degrees, and the first penetration direction T1 is perpendicular to the second penetration direction T2. Figure 4 The view control module 402 and Figure 1 as well as Figure 2 The difference in the viewing angle control module 102 is that the angle between the third alignment direction D3 and the fourth alignment direction D4 of the second liquid crystal layer LC2 has an angle θ, and the angle θ is greater than or equal to 45 degrees and less than 90 degrees. In some preferred embodiments, the angle θ falls within the range of 45 degrees to 65 degrees.

[0057] Refer to Table 2:

[0058]

[0059] In the comparative examples in Table 2, the privacy performance of structures having a single liquid crystal layer and two polarizing layers sandwiching that single liquid crystal layer was tested. In the third to sixth embodiments of the present invention, the following were tested: Figure 4 The privacy performance of the view control module 402 shown is illustrated with included angles θ of 90 degrees, 65 degrees, 60 degrees, and 45 degrees. Table 2 shows that the overall privacy performance is best when the included angle θ is 65 degrees. When the included angle θ is 60 degrees, the color shift in the privacy mode is minimal compared to the sharing mode. At an included angle θ of 60 degrees, the privacy performance is best at large angles.

[0060] Reference Figure 5 as well as Figure 6 ,in Figure 5 Part (A) illustrates a schematic diagram of a privacy display device 300 according to an embodiment of the present invention. Figure 5 Part (B) illustrates a schematic diagram of a privacy display device 400 according to an embodiment of the present invention. Figure 6 Part (A) illustrates a schematic diagram of a privacy display device 500 according to an embodiment of the present invention. Figure 6 Part (B) illustrates a schematic diagram of a privacy display device 600 according to an embodiment of the present invention.

[0061] The privacy display devices 300 and 400 include a display panel 201, a viewing angle control module 102, and a fourth polarizing layer P4. The display panel 201 is a liquid crystal display panel and is disposed on the first side S1 of the viewing angle control module 102, that is, the display panel 201 is disposed below the viewing angle control module 102.

[0062] For privacy display devices 300 and 400, the second penetration direction T2 is perpendicular to the first penetration direction T1 and the third penetration direction T3, the first alignment direction D1 of the first liquid crystal layer LC1 is perpendicular to the third alignment direction D3 of the second liquid crystal layer LC2, the second alignment direction D2 of the first liquid crystal layer LC1 is perpendicular to the fourth alignment direction D4 of the second liquid crystal layer LC2, and the third alignment direction D3 of the second liquid crystal layer LC2 is perpendicular to the fourth alignment direction D4 of the second liquid crystal layer LC2.

[0063] In the privacy display device 300, the first polarizing layer P1 and the second polarizing layer P2 are attached to the first liquid crystal layer LC1 in O-mode, and the second polarizing layer P2 and the third polarizing layer P3 are attached to the second liquid crystal layer LC2 in O-mode.

[0064] In the privacy display device 400, the first polarizing layer P1 and the second polarizing layer P2 are attached to the first liquid crystal layer LC1 in E-mode, and the second polarizing layer P2 and the third polarizing layer P3 are attached to the second liquid crystal layer LC2 in E-mode.

[0065] The privacy display devices 500 and 600 include a display panel 201, a viewing angle control module 102, and a fourth polarizing layer P4. The display panel 201 is a liquid crystal display panel and is disposed on the second side S2 of the viewing angle control module 102, that is, the display panel 201 is disposed above the viewing angle control module 102.

[0066] For privacy display devices 500 and 600, the second penetration direction T2 is perpendicular to the first penetration direction T1 and the third penetration direction T3, the first alignment direction D1 of the first liquid crystal layer LC1 is perpendicular to the third alignment direction D3 of the second liquid crystal layer LC2, the second alignment direction D2 of the first liquid crystal layer LC1 is perpendicular to the fourth alignment direction D4 of the second liquid crystal layer LC2, and the third alignment direction D3 of the second liquid crystal layer LC2 is perpendicular to the fourth alignment direction D4 of the second liquid crystal layer LC2.

[0067] In the privacy display device 500, the first polarizing layer P1 and the second polarizing layer P2 are attached to the first liquid crystal layer LC1 in E-mode, and the second polarizing layer P2 and the third polarizing layer P3 are attached to the second liquid crystal layer LC2 in E-mode.

[0068] In the privacy display device 600, the first polarizing layer P1 and the second polarizing layer P2 are attached to the first liquid crystal layer LC1 in O-mode, and the second polarizing layer P2 and the third polarizing layer P3 are attached to the second liquid crystal layer LC2 in O-mode.

[0069] Referring to Table 3, it explains the ratio of the brightness of the oblique viewing angle to the brightness of the normal viewing angle when the above-mentioned privacy display devices 300, 400, 500 and 600 are used for right-side privacy (i.e. 180-degree azimuth angle privacy).

[0070] Table 3:

[0071]

[0072]

[0073] As shown in Table 3, the privacy display device 400 has better optical performance than the privacy display device 300, and its relative brightness is lower at a side viewing angle of 45 degrees. The privacy display device 600 has better privacy performance than the privacy display device 500, and its relative brightness is lower at a side viewing angle of 45 degrees.

[0074] In summary, the privacy display device provided by this invention utilizes a dual TN liquid crystal structure to offer excellent privacy protection. Furthermore, the phase retardation of the dual TN liquid crystal layers falls within the range of 700nm to 1200nm, ensuring that the brightness and color saturation at the viewing angle do not exhibit significant differences between privacy mode and sharing mode.

[0075] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A privacy display device, characterized in that, include: Display panel; as well as The viewing angle control module includes a first polarizing layer, a first liquid crystal layer, a second polarizing layer, a third polarizing layer, and other layers stacked sequentially. The phase retardations of the first and second liquid crystal layers fall within the range of 700 nm to 1200 nm. The first and second polarizing layers are attached to the first liquid crystal layer in E-mode, and the second and third polarizing layers are attached to the second liquid crystal layer in O-mode. The viewing angle control module has a first side near the first polarizing layer and a second side near the third polarizing layer, and the display panel is disposed on the first side of the viewing angle control module or on the second side of the viewing angle control module. The first polarizing layer has a first transmission direction, the first liquid crystal layer has a first alignment direction close to the first polarizing layer and a second alignment direction away from the first polarizing layer, the second polarizing layer has a second transmission direction, the second liquid crystal layer has a third alignment direction close to the third polarizing layer and a fourth alignment direction away from the third polarizing layer, the third polarizing layer has a third transmission direction, the first transmission direction has a 45-degree azimuth angle, and the second transmission direction is not parallel to the first transmission direction and the third transmission direction, the first alignment direction is parallel to the third alignment direction, and the second alignment direction is parallel to the fourth alignment direction; It also includes a quarter-wave plate, wherein the display panel is a self-emissive display panel, the display panel is disposed on the first side, and the quarter-wave plate is disposed between the self-emissive display panel and the viewing angle control module, wherein the slow axis of the quarter-wave plate has a 90-degree azimuth angle and is 45 degrees away from the first penetration direction; When ambient light passes through the viewing angle control module, the linearly polarized light passing downward through the first polarizing layer will be formed as left-handed / right-handed light after penetrating the quarter-wave plate. This left-handed / right-handed light is reflected by the metal structure in the self-emissive display panel and formed as right-handed / left-handed light. After penetrating upward through the quarter-wave plate, it is formed as linearly polarized light perpendicular to the first penetration direction and is therefore blocked by the first polarizing layer.

2. The privacy display device as described in claim 1, characterized in that, The phase retardation of the first liquid crystal layer and the second liquid crystal layer falls within the range of 872 nm ± 100 nm.

3. The privacy display device as described in claim 1, characterized in that, The phase delays of the first liquid crystal layer and the second liquid crystal layer fall within the range of 1066 nm ± 100 nm.

4. The privacy display device as described in claim 1, characterized in that, The angle between the third alignment direction and the fourth alignment direction of the second liquid crystal layer is in the range of 45 degrees to 90 degrees.

5. The privacy display device as described in claim 4, characterized in that, The angle between the two corners is in the range of 45 degrees to 65 degrees.

6. The privacy display device as described in claim 4, characterized in that, The angle between the first alignment direction of the first liquid crystal layer and the second alignment direction of the first liquid crystal layer is 90 degrees.

7. The privacy display device as described in claim 4, characterized in that, The first penetration direction is perpendicular to the second penetration direction.

8. The privacy display device as claimed in claim 1, characterized in that, The second penetration direction is perpendicular to the first penetration direction and also perpendicular to the third penetration direction.

9. The privacy display device as claimed in claim 1, characterized in that, The second penetration direction is parallel to the second alignment direction of the first liquid crystal layer and perpendicular to the third alignment direction of the second liquid crystal layer.

10. The privacy display device as claimed in claim 9, characterized in that, The second penetration direction is perpendicular to both the first penetration direction and the third penetration direction.

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