Liquid crystal display device

Abstract

Provided is a thin liquid crystal display device in which two different images can be observed in the front and oblique directions of a single liquid crystal display panel, and in which the light utilization efficiency of a backlight is high. A liquid crystal display device (1) is provided with: a liquid crystal display panel (10); a parallax barrier (20) disposed so as to overlap the liquid crystal display panel, the parallax barrier (20) enabling a first image to be observed when viewed from a first direction (D1), and enabling a second image different from the first image to be observed when viewed from a second direction (D2) different from the first direction (D1); and a backlight (30) disposed on the back surface of the liquid crystal display panel, the first direction being the normal direction of the liquid crystal display panel, the backlight having a light guide plate (31) and a light source (32) that causes light to enter from a side surface of the light guide plate. The light emitted from the backlight to the liquid crystal display panel has a brightness peak in a range within 5 DEG with respect to the first direction and a range within 5 DEG with respect to the second direction.

Description

Technical Field

[0001] This invention relates to liquid crystal display devices. Background Technology

[0002] As one of the technologies of liquid crystal display devices, there is a technology that allows two different images to be observed using a single liquid crystal display panel depending on the viewing direction.

[0003] As a document related to such technology, there exists, for example, Patent Document 1. In Patent Document 1... Figure 2 , Figure 3 The abstract describes the following: A "multi-view display" is provided in which the same person can see two different images on one display and at the same time, the display size can be provided to make the images appear larger. The display consists of a first pixel group (24) arranged horizontally by pixels driven by a first image signal and a second pixel group (25) arranged horizontally by pixels driven by a second image signal, arranged alternately in the vertical direction. A parallax barrier (23) is set to separate the direction of light travel in the vertical direction, so that light reaches the first observation area (26) (driver's seat direction) from the first pixel group (24) and the second observation area (27) (windshield) from the second pixel group (25), so that the two different images are projected separately in the vertical direction. Thus, a driver can view two different images displayed on one display screen at a large size.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2006-330018 Summary of the Invention

[0007] However, in the technology described in Patent Document 1, such as Patent Document 1... Figure 2 , Figure 3 As shown, the observation is based on the premise that it is not observed from the normal direction of the dual-screen display (5), but from the oblique direction with a specified angle relative to the normal direction of the dual-screen display (5). Therefore, when directly observing the first observation area (26) (driver's seat direction), it is necessary to observe from the oblique direction instead of from the front of the dual-screen display (5), and there is a problem that it is impossible to observe from the front.

[0008] The problem to be solved by the present invention is to provide a thin liquid crystal display device with high light utilization efficiency of backlight, which enables two different images to be observed in the front and oblique directions of a liquid crystal display panel.

[0009] To solve the above-mentioned problems, the liquid crystal display device of the present invention is characterized by having: a liquid crystal display panel; a parallax barrier disposed in a manner overlapping the liquid crystal display panel, such that a first image can be observed when viewed from a first direction, and a second image different from the first image can be observed when viewed from a second direction different from the first direction; and a backlight source disposed on the back side of the liquid crystal display panel, wherein the first direction is the normal direction of the liquid crystal display panel, the backlight source has a light guide plate and a light source that causes light to enter from the side of the light guide plate, and the emitted light emitted from the backlight source toward the liquid crystal display panel has a brightness peak within a range of 5° relative to the first direction and within a range of 5° relative to the second direction.

[0010] Invention Effects

[0011] According to the present invention, a thin liquid crystal display device with high light utilization efficiency of backlight can be realized, which enables two different images to be observed in the front and oblique directions of a liquid crystal display panel. Attached Figure Description

[0012] Figure 1 This is a cross-sectional view of the liquid crystal display device in an embodiment.

[0013] Figure 2 This is a top view of the backlight in the embodiment.

[0014] Figure 3 yes Figure 2 AA sectional view.

[0015] Figure 4 yes Figure 2 BB cross-sectional view.

[0016] Figure 5 This is a cross-sectional view illustrating the structure of the second lens film in the embodiment.

[0017] Figure 6 This is a diagram illustrating an example of the brightness distribution of the backlight in a comparative example.

[0018] Figure 7 This is a diagram illustrating the first example of the brightness distribution of the backlight in the embodiment.

[0019] Figure 8 This is a diagram illustrating the brightness distribution of the backlight in the embodiment.

[0020] Figure 9 This is a diagram illustrating the brightness distribution of the backlight in the embodiment, representing a third example.

[0021] Explanation of reference numerals in the attached figures

[0022] 1: Liquid Crystal Display Device

[0023] 10: LCD display panel

[0024] 20: Parallax barrier

[0025] 20A: Transmission area

[0026] 20B: Covered Area

[0027] 30: Backlight

[0028] 31: Light guide plate

[0029] 31A: Linear Prism Array No. 1

[0030] 31B: Second linear prism array

[0031] 31C: Side view

[0032] 32: Light source

[0033] 33: Reflective film

[0034] 34: First lens film

[0035] 34A: Third linear prism array

[0036] 35: Second lens film

[0037] 35A: Area 1

[0038] 35B: Area 2

[0039] 35C: Linear prism

[0040] 35D: Prism Spacing

[0041] 35E: Prism width

[0042] 36: Collimated light

[0043] 100: Reflector

[0044] θ: Angle

[0045] D1: Direction 1

[0046] D2: Second Direction

[0047] L1: First Light

[0048] L2: Second Light

[0049] L2': Reflected light

[0050] LU: Brightness

[0051] P1: First peak value

[0052] P2: Second peak Detailed Implementation

[0053] Hereinafter, embodiments of the present invention will be described using the accompanying drawings. In the various figures and embodiments, the same or similar structural elements are labeled with the same reference numerals, and repeated descriptions are omitted.

[0054] Figure 1 This is a cross-sectional view of the liquid crystal display device in an embodiment.

[0055] In this embodiment, a vehicle-mounted liquid crystal display device 1 is envisioned, and an example is given where the driver, as the observer, can see different images when directly viewing the liquid crystal display device 1 and when viewing, for example, an image reflected on a reflector 100 such as a windshield. It should be noted that this is not a limitation, and it can also be used for other purposes.

[0056] The liquid crystal display device 1 of this embodiment includes a liquid crystal display panel 10, a parallax barrier 20, and a backlight 30.

[0057] The LCD panel 10 can use a regular LCD panel.

[0058] The backlight 30 is disposed on the back of the liquid crystal display panel 10. Details of the backlight 30 in this embodiment will be described later.

[0059] The parallax barrier 20 is configured to overlap with the liquid crystal display panel 10 and is a barrier that enables the observation of a first image when viewed from a first direction D1 and a second image different from the first image when viewed from a second direction D2 different from the first direction D1.

[0060] In this embodiment, an example is shown in which the parallax barrier 20 is disposed on the back side of the liquid crystal display panel 10, but it is not limited thereto, and the parallax barrier 20 may also be disposed on the front surface side of the liquid crystal display panel 10.

[0061] In this embodiment, it is envisioned that the liquid crystal display device 1 is tilted and fixed at an angle of 60° relative to the horizontal direction, and the second direction D2 is higher than the first direction D1. Therefore, the parallax barrier 20 is a structure in which the transmission area 20A extending in the left-right direction and the shielding area 20B extending in the left-right direction are alternately arranged in the up-down direction.

[0062] In the liquid crystal display panel 10, corresponding to the arrangement of the transmission region 20A and the shielding region 20B of the parallax barrier 20, a first pixel region extending in the left-right direction for displaying a first image and a second pixel region extending in the left-right direction for displaying a second image are alternately arranged in the vertical direction. Light emitted from the backlight 30 in the first direction D1 passes through the transmission region 20A and the first pixel region of the parallax barrier 20 and is observed as first light L1, but because it is shielded by the shielding region 20B, it does not reach the second pixel region and is not included in the first light L1. Similarly, light emitted from the backlight 30 in the second direction D2 passes through the transmission region 20A and the second pixel region of the parallax barrier 20 and is observed as second light L2, but because it is shielded by the shielding region 20B, it does not reach the first pixel region and is not included in the second light L2. As a result, the resolution is reduced to half, but the first image can be observed when viewed from the first direction D1, and the second image can be observed when viewed from the second direction D2.

[0063] The first light L1 emitted from the liquid crystal display panel 10 in the first direction D1 can be directly observed by an observer. On the other hand, the second light L2 emitted from the liquid crystal display panel 10 in the second direction D2 is totally reflected by the reflector 100 and becomes reflected light L2', which is indirectly observed by an observer. From the observer's perspective, the first image is directly displayed on the liquid crystal display panel 10, and the second image appears to be displayed on a reflector 100, such as a windshield. The first image can display at least one instrument, such as a speedometer. The second image can display at least one of the following: an emergency warning, a map, or traffic information.

[0064] In this embodiment, the first direction D1 is set as the normal direction of the liquid crystal display panel 10. Therefore, when the observer observes directly, it can be observed from the front rather than from an oblique angle, thus providing good visual recognition.

[0065] It should be noted that the angle θ between the first direction D1 and the second direction D2 is expected to be 55° to 65°. This makes it easy to project the second image onto a reflector 100, such as the windshield. However, it is not limited to this and other angles can also be used.

[0066] Moreover, in this embodiment, as described below Figures 7 to 9As shown, the emitted light from the backlight 30 to the liquid crystal display panel 10 has peak values ​​of luminance LU (first peak value P1, second peak value P2) within a range of 5° relative to the first direction D1 and within a range of 5° relative to the second direction D2. Therefore, a liquid crystal display device 1 with high light utilization efficiency of the backlight 30 can be achieved. It should be noted that, in this embodiment, the peak value of luminance LU indicates that the emitted light from the backlight 30 is directional, and refers to light that does not include non-directional diffuse light with locally small peak values.

[0067] Next, details of the backlight 30 in this embodiment will be explained.

[0068] Figure 2 This is a top view of the backlight in the embodiment. Figure 3 yes Figure 2 AA sectional view. Figure 4 yes Figure 2 BB cross-sectional view. Figure 5 This is a cross-sectional view illustrating the structure of the second lens film in the embodiment.

[0069] like Figure 2 and Figure 3 As shown, the backlight 30 of this embodiment has a light guide plate 31 and a light source 32 that allows light to enter from the side 31C of the light guide plate 31. This enables a thin backlight 30, thus realizing a thin liquid crystal display device 1.

[0070] In addition, such as Figure 3 As shown, the backlight 30 of this embodiment has a reflective film 33 disposed on the back side of the light guide plate 31, a first lens film 34 disposed between the light guide plate 31 and the liquid crystal display panel 10, and a second lens film 35 disposed between the first lens film 34 and the liquid crystal display panel 10.

[0071] It should be noted that, in Figure 2 In the image, the first lens film 34 and the second lens film 35 are shown through a perspective view to allow the light guide plate 31 to be seen. Additionally, in... Figure 2 In the middle, the reflective film 33 is hidden on the back of the light guide plate 31.

[0072] And, as Figure 5 As shown, collimated light 36 is emitted from the first lens film 34, and the second lens film 35 has a first region 35A that emits the incident collimated light 36 in a first direction D1 and a second region 35B that has a linear prism 35C that emits the incident collimated light 36 in a second direction D2. The first region 35A and the second region 35B are arranged alternately.

[0073] The linear prism 35C of the second lens film 35 is formed on the side of the liquid crystal display panel 10, extending along the side surface 31C of the light guide plate 31 into which light from the light source 32 is incident. It is desirable that the first base angle is 55–59° and the second base angle is 83–87°, more preferably 57° and 85°. It should be noted that the first and second base angles are not limited to these values, and can be appropriately varied according to the second direction D2.

[0074] The desired density of the linear prism 35C in the second lens film 35 is 30% to 70%. It should be noted that the density of the linear prism 35C is the ratio of the prism width 35E to the prism spacing 35D, where the prism spacing 35D corresponds to the combined width of the first region 35A and the second region 35B, and the prism width 35E corresponds to the width of the second region 35B. By changing the density of the linear prism 35C, as described later... Figures 7 to 9 As explained, the ratio of the brightness LU in the first direction D1 to the brightness LU in the second direction D2 can be adjusted.

[0075] Next, the structure for emitting collimated light 36 from the first lens film 34 will be described.

[0076] like Figure 3 and Figure 4 As shown, the light guide plate 31 has a first linear prism array 31A formed on the side of the reflective film 33 and extending along the side surface 31C where light from the light source 32 is incident, and a second linear prism array 31B formed on the side of the first lens film 34 and extending in a direction orthogonal to the extending direction of the first linear prism array 31A.

[0077] The first lens film 34 has a third linear prism array 34A formed on the side of the light guide plate 31 and extending along the side surface 31C of the light guide plate 31 into which light from the light source 32 is incident.

[0078] The first linear prism array 31A is an isosceles triangle with a desired vertex angle of 174–178°, and more preferably 176°.

[0079] The second linear prism array 31B is an isosceles triangle, with a desired vertex angle of 55–65° or 95–100°, and more preferably 60°.

[0080] The third linear prism array 34A is an isosceles triangle with a desired vertex angle of 66-68°, and more preferably 68°.

[0081] Figure 6 This is a diagram illustrating an example of the brightness distribution of the backlight in a comparative example.

[0082] The backlight 30 of the comparative example corresponds to the structure of removing the second lens film 35 from the backlight 30 of this embodiment.

[0083] Figure 6 An example of the brightness distribution is shown when the first linear prism array 31A is an isosceles triangle with a vertex angle of 176°, the second linear prism array 31B is an isosceles triangle with a vertex angle of 60°, and the third linear prism array 34A is an isosceles triangle with a vertex angle of 68°. Figure 6 In the diagram, the horizontal axis is the angle θ [°] formed by the first direction D1 (normal direction) and the second direction D2, and the vertical axis is the normalized luminance LU [au].

[0084] like Figure 6 As shown, the first peak P1 is located near the first direction D1 (normal direction), i.e., near the angle θ = 0°, and there is no other peak (second peak P2). Therefore, it can be seen that the backlight 30 of the comparative example emits collimated light 36 from the first lens film 34.

[0085] Figure 7 This is a diagram illustrating the first example of the brightness distribution of the backlight in the embodiment. Figure 8 This is a diagram illustrating the brightness distribution of the backlight in the embodiment. Figure 9 This is a diagram illustrating the brightness distribution of the backlight in the third example of the embodiment. Figures 7 to 9 In the middle, the horizontal and vertical axes are parallel to each other. Figure 6 same.

[0086] exist Figures 7 to 9 In the comparison example, the shapes of the first linear prism array 31A, the second linear prism array 31B, and the third linear prism array 34A are similar to those of the first linear prism array 31A, the second linear prism array 31B, and the third linear prism array 34A. Figure 6 Same. In the linear prism 35C of the second lens film 35, the first base angle is 57° and the second base angle is 85°. Regarding the density of the linear prism 35C in the second lens film 35, in Figure 7 30%, in Figure 8 It is 50%, in Figure 9 It is 70%.

[0087] like Figures 7 to 9 As shown, the backlight 30 of this embodiment has a first peak value P1 in the first direction D1 (normal direction), i.e., near angle θ = 0°, and a second peak value P2 in the second direction D2, i.e., near angle θ = 60°. The ratio of peak brightness (first peak value P1 : second peak value P2) is... Figure 7 The ratio is 1.00:0.53. Figure 8 The ratio is 0.80:1.00. Figure 9 The ratio is 0.48:1.00. In this way, by changing the density of the linear prism 35C, the ratio of the brightness LU in the first direction D1 to the brightness LU in the second direction D2 can be adjusted.

[0088] As described above, according to this embodiment, a thin liquid crystal display device 1 with high light utilization efficiency of the backlight 30 can be realized, which enables the observation of two different images in the front and oblique directions of a liquid crystal display panel 10.

[0089] The embodiments of the present invention have been described above, but the present invention is not limited to the structures described in the embodiments, and various modifications can be made within the scope of the technical concept of the present invention. In addition, some or all of the structures described in the embodiments can be combined for application.

Claims

1. A liquid crystal display device, characterized in that, have: LCD display panel; A parallax barrier, configured to overlap with the liquid crystal display panel, allows a first image to be observed when viewed from a first direction, and a second image different from the first image to be observed when viewed from a second direction different from the first direction; and A backlight is disposed on the back of the liquid crystal display panel. The first direction is the normal direction of the liquid crystal display panel. The backlight has a light guide plate and a light source that allows light to enter from the side of the light guide plate. The emitted light from the backlight to the liquid crystal display panel has a brightness peak within a range of 5° relative to the first direction and within a range of 5° relative to the second direction.

2. The liquid crystal display device according to claim 1, characterized in that, The angle between the first direction and the second direction is 55° to 65°.

3. The liquid crystal display device according to claim 1, characterized in that, The backlight source has a reflective film disposed on the back side of the light guide plate, a first lens film disposed between the light guide plate and the liquid crystal display panel, and a second lens film disposed between the first lens film and the liquid crystal display panel. Collimated light is emitted from the first lens film. The second lens film has a first region that directs the incident collimated light toward the first direction, and a second region that has a linear prism that directs the incident collimated light toward the second direction, the first region and the second region being alternately arranged.

4. The liquid crystal display device according to claim 3, characterized in that, The light guide plate has a first linear prism array formed on the side of the reflective film and extending along the side where light from the light source is incident, and a second linear prism array formed on the side of the first lens film and extending in a direction orthogonal to the extending direction of the first linear prism array. The first lens film has a third linear prism array formed on the side of the light guide plate and extending along the side where the light from the light source is incident.

5. The liquid crystal display device according to claim 4, characterized in that, The first linear prism array is an isosceles triangle with a vertex angle of 174–178°. The second linear prism array is an isosceles triangle with a vertex angle of 55–65° or 95–100°. The third linear prism array is an isosceles triangle with a vertex angle of 66-68°.

6. The liquid crystal display device according to claim 3, characterized in that, The linear prism of the second lens film is formed on the side of the liquid crystal display panel and extends along the side where the light from the light source is incident, with a first base angle of 55-59° and a second base angle of 83-87°.

7. The liquid crystal display device according to claim 3, characterized in that, The density of the linear prism in the second lens film is 30% to 70%.

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