Liquid crystal display device

Abstract

The present invention provides a liquid crystal display device 1 that allows two different images to be observed from the front and at an oblique angle on a single liquid crystal display panel 10, and is thin and highly efficient in utilizing the light of the backlight 30. [Solution] The liquid crystal display device 1 includes a liquid crystal display panel 10, a parallax barrier 20 positioned to overlap the liquid crystal display panel 10 so that a first image can be observed when viewed from a first direction D1 and a second image different from the first image can be observed when viewed from a second direction D2 different from the first direction D1, and a backlight 30 positioned on the back of the liquid crystal display panel 10, wherein the first direction D1 is the normal direction of the liquid crystal display panel 10, and the backlight 30 includes a light guide plate 31 and a light source 32 that causes light to be incident from the side of the light guide plate 31, and the emitted light emitted from the backlight 30 to the liquid crystal display panel 10 has brightness peaks in a range of 5° from the first direction D1 and in a range of 5° from the second direction D2.

Description

Technical Field

[0001] The present invention relates to a liquid crystal display device.

Background Art

[0002] As one of the technologies of liquid crystal display devices, there is a technology that can observe two different images according to the viewing direction using one liquid crystal display panel.

[0003] As a document related to such technology, for example, there is Patent Document 1. In FIGS. 2, 3, and the summary of Patent Document 1, it is possible to provide a "multi-view display" in which the same person can view two different images using one display, and moreover, a first pixel group (24) formed by arranging pixels driven by a first video signal horizontally and a second pixel group (25) formed by arranging pixels driven by a second video signal horizontally are alternately arranged vertically, respectively, and a parallax barrier (the traveling direction of light is separated vertically so that light reaches the first observation region (26) (driver's seat direction) from the first pixel group (24) and light reaches the second observation region (27) (front glass) from the second pixel group (25). By distributing and projecting two different images in the vertical direction, it is described that one driver can view two different images displayed on one display screen together in a large size.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the technology described in Patent Document 1, as shown in Figures 2 and 3 of Patent Document 1, assumes observation from an oblique direction having a predetermined angle with respect to the normal direction of the dual-view display (5), rather than from the normal direction of the dual-view display (5). Therefore, when directly observing the first observation area (26) (driver's seat direction), it is necessary to observe from an oblique direction rather than from the front of the dual-view display (5), resulting in the problem that it cannot be observed from the front.

[0006] The problem that this invention aims to solve is to provide a liquid crystal display device that allows two different images to be observed from the front and at an oblique angle on a single liquid crystal display panel, and that is thin and has high light utilization efficiency of the backlight. [Means for solving the problem]

[0007] To solve the above-mentioned problems, the liquid crystal display device of the present invention comprises a liquid crystal display panel, a parallax barrier arranged to overlap the liquid crystal display panel so 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 arranged on the back of the liquid crystal display panel, wherein the first direction is the normal direction of the liquid crystal display panel, and the backlight comprises a light guide plate and a light source that causes light to be incident from the side of the light guide plate, wherein the emitted light emitted from the backlight to the liquid crystal display panel has a luminance peak in a range of 5° from the first direction and in a range of 5° from the second direction. [Effects of the Invention]

[0008] According to the present invention, two different images can be observed from the front and at an oblique angle of a single liquid crystal display panel, enabling the realization of a thin liquid crystal display device with high light utilization efficiency of the backlight. [Brief explanation of the drawing]

[0009] [Figure 1] Cross-sectional view of the liquid crystal display device of the embodiment. [Figure 2] Top view of the backlight in the embodiment. [Figure 3] Cross-sectional view AA in Figure 2. [Figure 4] Cross-sectional view of BB in Figure 2. [Figure 5] A cross-sectional view illustrating the configuration of the second lens film in the embodiment. [Figure 6] A diagram showing an example of the backlight brightness distribution in a comparative example. [Figure 7] A figure showing a first example of the luminance distribution of the backlight in the embodiment. [Figure 8] A figure showing a second example of the luminance distribution of the backlight in the embodiment. [Figure 9] A figure showing a third example of the luminance distribution of the backlight in the embodiment. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described below with reference to the drawings. In each figure and embodiment, the same or similar components are denoted by the same reference numerals, and redundant explanations are omitted.

[0011] Figure 1 is a cross-sectional view of the liquid crystal display device according to the embodiment.

[0012] In this embodiment, we assume an in-vehicle liquid crystal display device 1 and will explain using an example in which different images can be seen when the driver, as the observer, directly observes the liquid crystal display device 1 and when the driver observes the image reflected by a reflector 100 such as the windshield. However, this is not the only example, and it may be used for other purposes as well.

[0013] The liquid crystal display device 1 of this embodiment includes a liquid crystal display panel 10, a parallax barrier 20, and a backlight 30.

[0014] The liquid crystal display panel 10 can use a general-purpose liquid crystal display panel.

[0015] The backlight 30 is disposed on the back surface of the liquid crystal display panel 10. Details of the backlight 30 of this embodiment will be described later.

[0016] The parallax barrier 20 is disposed so as to overlap the liquid crystal display panel 10, and is a barrier for enabling a first video to be observed when viewed from a first direction D1 and a second video different from the first video to be observed when viewed from a second direction D2 different from the first direction D1.

[0017] In this embodiment, an example in which the parallax barrier 20 is disposed on the back side of the liquid crystal display panel 10 is shown, but the present invention is not limited to this, and the parallax barrier 20 may be disposed on the front side of the liquid crystal display panel 10.

[0018] In this embodiment, it is assumed that the liquid crystal display device 1 is obliquely fixed at an angle of 60° with respect to the horizontal direction and the second direction D2 is above the first direction D1. Therefore, the parallax barrier 20 has a configuration in which transmission regions 20A extending in the left-right direction and shielding regions 20B extending in the left-right direction are alternately arranged in the up-down direction.

[0019] In the liquid crystal display panel 10, corresponding to the arrangement of the transmission regions 20A and the shielding regions 20B of the parallax barrier 20, a first pixel region extending in the left-right direction for displaying a first video and a second pixel region extending in the left-right direction for displaying a second video are alternately arranged in the up-down direction. The light emitted from the backlight 30 toward the first direction D1 passes through the transmission region 20A of the parallax barrier 20 and the first pixel region and is observed as the first light L1, but does not reach the second pixel region because it is shielded by the shielding region 20B and is not included in the first light L1. Similarly, the light emitted from the backlight 30 toward the second direction D2 passes through the transmission region 20A of the parallax barrier 20 and the second pixel region and is observed as the second light L2, but does not reach the first pixel region because it is shielded by the shielding region 20B and is not included in the second light L2. As a result, the resolution is halved, but the first video can be observed when viewed from the first direction D1, and the second video can be observed when viewed from the second direction D2.

[0020] The first light L1 emitted from the liquid crystal display panel 10 in the first direction D1 is directly observed by the 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 to become the reflected light L2', and is indirectly observed by the observer. When viewed from the observer, the first image is directly displayed on the liquid crystal display panel 10, and the second image appears to be displayed on the reflector 100 such as the windshield. As the first image, at least one of meters such as a speedometer can be displayed. As the second image, at least one of, for example, an abnormality warning, a map, traffic information, etc. can be displayed.

[0021] In this embodiment, the first direction D1 is the normal direction of the liquid crystal display panel 10. Thereby, when the observer observes directly, the observer can observe from the front rather than obliquely, so the visibility is good.

[0022] It is desirable that the angle θ formed between the first direction D1 and the second direction D2 is 55 to 65°. Thereby, it becomes easier to project the second image onto the reflector 100 such as the windshield. However, it is not limited to this, and another angle may be used.

[0023] Furthermore, in this embodiment, as shown in FIGS. 7 to 9 described later, the emitted light emitted from the backlight 30 to the liquid crystal display panel 10 has peaks of luminance LU (the first peak P1, the second peak P2) within a range of 5° or less from the first direction D1 and within a range of 5° or less from the second direction D2. Thereby, the liquid crystal display device 1 with high light utilization efficiency of the backlight 30 can be realized. Note that having a peak of luminance LU in this embodiment means that the emitted light from the backlight 30 has directivity, and it means that diffused light without directivity is not included even if it has a locally minute peak.

[0024] Next, the details of the backlight 30 of this embodiment will be described.

[0025] Figure 2 is a top view of the backlight of the embodiment. Figure 3 is a cross-sectional view of AA in Figure 2. Figure 4 is a cross-sectional view of BB in Figure 2. Figure 5 is a cross-sectional view illustrating the configuration of the second lens film of the embodiment.

[0026] As shown in Figures 2 and 3, the backlight 30 of this embodiment has a light guide plate 31 and a light source 32 that emits light from the side surface 31C of the light guide plate 31. This makes it possible to create a thin backlight 30, and thus realize a thin liquid crystal display device 1.

[0027] Furthermore, as shown in Figure 3, the backlight 30 of this embodiment includes a reflective film 33 positioned on the back side of the light guide plate 31, a first lens film 34 positioned between the light guide plate 31 and the liquid crystal display panel 10, and a second lens film 35 positioned between the first lens film 34 and the liquid crystal display panel 10.

[0028] In Figure 2, the first lens film 34 and the second lens film 35 are shown through the lens so that the light guide plate 31 is visible. Also, in Figure 2, the reflective film 33 is hidden behind the light guide plate 31.

[0029] As shown in Figure 5, 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 in which a linear prism 35C is formed that emits the incident collimated light 36 in a second direction D2, with the first region 35A and the second region 35B being arranged alternately.

[0030] The linear prism 35C of the second lens film 35 is formed on the liquid crystal display panel 10 side and extends along the side surface 31C of the light guide plate 31 into which light from the light source 32 enters. Preferably, the first base angle is 55-59° and the second base angle is 83-87°, and more preferably, the first base angle is 57° and the second base angle is 85°. However, the first and second base angles are not limited to these and may be appropriately changed according to the second direction D2.

[0031] The density of the linear prism 35C in the second lens film 35 is preferably 30% to 70%. The density of the linear prism 35C is the ratio of the prism width 35E to the prism pitch 35D, where the prism pitch 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, the ratio of the luminance LU in the first direction D1 to the luminance LU in the second direction D2 can be adjusted, as explained later in Figures 7 to 9.

[0032] Next, the structure for emitting collimated light 36 from the first lens film 34 will be described.

[0033] As shown in Figures 3 and 4, the light guide plate 31 has a first linear prism array 31A formed on the reflective film 33 side and extending along the side surface 31C into which light from the light source 32 is incident, and a second linear prism array 31B formed on the first lens film 34 side and extending in a direction perpendicular to the direction of extension of the first linear prism array 31A.

[0034] The first lens film 34 is formed on the light guide plate 31 side and has a third linear prism array 34A that extends along the side surface 31C of the light guide plate 31 into which light from the light source 32 enters.

[0035] The first linear prism array 31A is an isosceles triangle, and its vertex angle is preferably 174-178°, and more preferably 176°.

[0036] The second linear prism array 31B is an isosceles triangle, with a vertex angle of preferably 55-65° or 95-100°, and more preferably 60°.

[0037] The third linear prism array 34A is an isosceles triangle, and it is preferable that the vertex angle is 66-68°, and more preferably 68°.

[0038] Figure 6 shows an example of the luminance distribution of the backlight in a comparative example.

[0039] The comparative backlight 30 corresponds to the configuration of the backlight 30 in this embodiment, but with the second lens film 35 removed.

[0040] Figure 6 shows an example of the luminance distribution 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°. In Figure 6, the horizontal axis is the angle θ [°] between the first direction D1 (normal direction) and the second direction D2, and the vertical axis is the normalized luminance LU [au].

[0041] As shown in Figure 6, the first peak P1 is located near the angle θ=0° in the first direction D1 (normal direction), and there are no other peaks (second peak P2). Therefore, it can be seen that the comparative example backlight 30 emits collimated light 36 from the first lens film 34.

[0042] Figure 7 shows a first example of the backlight brightness distribution in the embodiment. Figure 8 shows a second example of the backlight brightness distribution in the embodiment. Figure 9 shows a third example of the backlight brightness distribution in the embodiment. In Figures 7 to 9, the horizontal and vertical axes are the same as in Figure 6.

[0043] In Figures 7 to 9, the shapes of the first linear prism array 31A, the second linear prism array 31B, and the third linear prism array 34A are the same as those in the comparative example shown in Figure 6. The linear prism 35C of the second lens film 35 has a first base angle of 57° and a second base angle of 85°. The density of the linear prism 35C in the second lens film 35 is 30% in Figure 7, 50% in Figure 8, and 70% in Figure 9.

[0044] As shown in Figures 7 to 9, the backlight 30 of this embodiment has a first peak P1 at an angle θ=0° in the first direction D1 (normal direction) and a second peak P2 at an angle θ=60° in the second direction D2. The ratio of the peak luminances (first peak P1:second peak P2) was 1.00:0.53 in Figure 7, 0.80:1.00 in Figure 8, and 0.48:1.00 in Figure 9. In this way, the ratio of the luminance LU in the first direction D1 to the luminance LU in the second direction D2 can be adjusted by changing the density of the linear prism 35C.

[0045] As described above, according to this embodiment, two different images can be observed from the front and oblique angles of a single liquid crystal display panel 10, and a thin liquid crystal display device 1 with high light utilization efficiency of the backlight 30 can be realized.

[0046] Although embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible within the scope of the technical idea of ​​the present invention. Furthermore, some or all of the configurations described in the embodiments may be applied in combination. [Explanation of symbols]

[0047] 1:LCD display device 10: LCD display panel 20: Parallax Barrier 20A:Transmission area 20B: Shield area 30: Backlight 31: Light guide plate 31A: First linear prism array 31B: Second linear prism array 31C: Side 32: Light source 33: Reflective film 34: The first lens film 34A: Third linear prism array 35: The Second Lens Film 35A: First area 35B: Second Domain 35C: Linear prism 35D: Prism Pitch 35E: Prism width 36: Collimated light 100:Reflector θ: Angle D1: First direction D2: Second direction L1: First Light L2: Second Light L2': Reflected light LU: Brightness P1: First peak P2: Second peak

Claims

1. LCD display panel, A parallax barrier is positioned to overlap the liquid crystal display panel, allowing 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. The liquid crystal display panel has a backlight located on the back of the panel, The first direction is the normal direction of the liquid crystal display panel, The backlight comprises a light guide plate and a light source that causes light to be incident on the side of the light guide plate. A liquid crystal display device characterized in that the emitted light emitted from the backlight to the liquid crystal display panel has a brightness peak in a range of 5° from the first direction and a range of 5° from the second direction.

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

3. In claim 1, The backlight comprises 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 liquid crystal display device is characterized in that the second lens film has a first region that emits the incident collimated light in a first direction and a second region in which a linear prism is formed that emits the incident collimated light in a second direction, and the first region and the second region are arranged alternately.

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

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

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

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

Images