JP6959742B2 - Liquid crystal display and liquid crystal module - Google Patents

Description

The present invention relates to a liquid crystal display device including a plurality of liquid crystal cells and a liquid crystal module constituting the liquid crystal display device.

A liquid crystal display device in which a plurality of liquid crystal cells are stacked and used has been developed (for example, Patent Documents 1 to 4). By using such a liquid crystal display device, for example, various different display patterns can be displayed in a desired display area.

Japanese Unexamined Patent Publication No. 2001-066626 Japanese Unexamined Patent Publication No. 2003-043449 Japanese Unexamined Patent Publication No. 2003-195344 Japanese Unexamined Patent Publication No. 2008-158174

A main object of the present invention is to provide a liquid crystal display device having a novel structure in a liquid crystal display device in which a plurality of liquid crystal cells are arranged in an overlapping manner. Another object is to improve the display quality of a liquid crystal display device in which a plurality of liquid crystal cells are arranged in an overlapping manner.

According to the main viewpoint of the present invention, the light source, a pair of polarizing plates arranged apart from each other on the optical axis of the light source, and the pair of polarizing plates arranged between the pair of polarizing plates and orthogonal to the optical axis of the light source. It has a first liquid crystal cell that is tilted at a first angle and a second liquid crystal cell that is arranged between the pair of polarizing plates, and the first liquid crystal cell is arranged so as to face each other. The first substrate and the second substrate are provided with a first substrate and a second substrate, and a first liquid crystal layer sandwiched between the first substrate and the second substrate. The first liquid crystal layer is oriented in the first direction when no voltage is applied, and the second liquid crystal cells are arranged to face each other. The third substrate and the fourth substrate are provided with a third substrate and a fourth substrate, and a second liquid crystal layer sandwiched between the third substrate and the fourth substrate. The second liquid crystal layer is oriented in the second direction when no voltage is applied, and the alignment film of the first substrate and the alignment film of the first substrate are provided. The orientation treatment of the alignment film of the third substrate is the same, the orientation treatment of the alignment film of the second substrate and the alignment film of the fourth substrate are the same, and the orientation treatment is the same, as viewed from one side of the pair of polarizing plates. At that time, a liquid crystal display device is provided in which the first and second liquid crystal cells are arranged so that the liquid crystal molecular orientation directions face the same direction.

In a liquid crystal display device in which a plurality of liquid crystal cells are arranged in an overlapping manner, the display quality is improved.

FIG. 1A is a cross-sectional view showing a basic configuration of a liquid crystal display device according to a reference example, and FIG. 1B is a plan view showing a display surface of the liquid crystal display device. FIG. 2A is a cross-sectional view showing how to measure the optical characteristics of a plurality of liquid crystal cells constituting the liquid crystal display device, and FIGS. 2B and 2C show the inclination angle (observation angle) of the light transmittance of the liquid crystal cells. It is a graph which shows sex. and, 3A to 3D are cross-sectional views showing a liquid crystal display device according to the first to fourth embodiments, respectively. It is a top view which illustrates the electrode pattern of the liquid crystal cell by an Example.

FIG. 1A is a cross-sectional view showing a basic structure of a liquid crystal display device according to a reference example. For convenience, the relative size and positional relationship of each component is different from the actual one.

The liquid crystal display device 110 according to the reference example includes first and second liquid crystal cells 10 and 20, a pair of polarizing plates 31 and 32, and a light source 40. As the light source 40, for example, a fluorescent lamp or an LED light can be used. Alternatively, an edge light type backlight unit using a light guide plate may be used.

A pair of polarizing plates 31 and 32 are arranged on the optical axis of the light source 40 at intervals from each other. The first and second liquid crystal cells 10 and 20 are arranged between the pair of polarizing plates 31 and 32. From the light source 40 side, one polarizing plate (back side polarizing plate) 31, the first liquid crystal cell (back side liquid crystal cell) 10, the second liquid crystal cell (front side liquid crystal cell) 20, and the other polarizing plate (front side polarizing plate). ) 32 are arranged side by side in order. The first and second liquid crystal cells 10 and 20 and the pair of polarizing plates 31 and 32 may be collectively referred to as a liquid crystal module.

The first liquid crystal cell 10 is a multiplex drive VA (vertical alignment) type liquid crystal cell having a so-called dot matrix type electrode structure. The first liquid crystal cell 10 includes a lower substrate 11 and an upper substrate 12 arranged to face each other, and a liquid crystal layer 17 sandwiched between the lower substrate 11 and the upper substrate 12.

The lower substrate 11 and the upper substrate 12 are transparent substrates such as a glass substrate and a plastic substrate, respectively. Specifically, a 0.7 mm thick soda lime glass substrate can be used. The lower substrate 11 and the upper substrate 12 are bonded to each other with a gap of, for example, 5 μm. The gap between the lower substrate 11 and the upper substrate 12 is held by a lot-shaped or spherical spacer contained in a frame-shaped sealing material (not shown) and spherical spacers uniformly dispersed in the substrate surface.

A striped lower electrode 13 extending in one direction is provided on one surface side of the lower substrate 11 (the side facing the upper substrate 12). Similarly, a striped upper electrode 14 extending in a direction intersecting the lower electrode 13 is provided on one surface side of the upper substrate 12 (the side facing the lower substrate 11). These electrodes 13 and 14 are formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), respectively. It is assumed that the electrodes 13 and 14 are centrally formed near the center of the substrate, respectively.

The lower alignment film 15 is provided on one surface side of the lower substrate 11 so as to cover the lower electrode 13. Similarly, the upper alignment film 16 is provided on one surface side of the upper substrate 12 so as to cover the upper electrode 14. As these alignment films 15 and 16, vertical alignment films that regulate the alignment state of the liquid crystal layer 17 in the vertical orientation (substrate normal direction) are used. Each alignment film is subjected to a uniaxial alignment treatment such as a rubbing treatment so as to be antiparallel to each other (the directions of the uniaxial alignment treatment are indicated by arrows 15r and 16r in the drawing).

The liquid crystal layer 17 is provided between the lower substrate 11 and the upper substrate 12 so as to be surrounded by a frame-shaped sealing material (not shown). The liquid crystal member constituting the liquid crystal layer 17 is filled in the space defined by the lower substrate 11, the upper substrate 12, and the frame-shaped sealing material. As the liquid crystal material, for example, a negative liquid crystal material manufactured by Merck Co., Ltd. (birefringence Δn = 0.18, dielectric anisotropy Δε = −2.0) can be used.

When no voltage is applied, the orientation direction of the liquid crystal molecules constituting the liquid crystal layer 17 is substantially perpendicular to the substrate surfaces of the lower substrate 11 and the upper substrate 12. The pretilt angle of the liquid crystal molecules is about 89.85 °. In the figure, the liquid crystal molecule orientation direction is indicated by an arrow 17d. When a voltage is applied, the orientation direction of the liquid crystal molecules is substantially horizontal to the substrate surfaces of the lower substrate 11 and the upper substrate 12.

The second liquid crystal cell 20 is a VA type liquid crystal cell having a so-called segment type electrode structure. The second liquid crystal cell 20 includes a lower substrate 21 and an upper substrate 22 arranged to face each other, and a liquid crystal layer 27 sandwiched between the upper substrate 21 and the lower substrate 22.

The lower substrate 21 and the upper substrate 22 are, for example, 0.7 mm thick soda lime glass substrates. The lower substrate 21 and the upper substrate 22 are bonded to each other with a gap of, for example, 4 μm.

A common electrode (solid electrode) 23 is provided on one side of the lower substrate 21 (the side facing the upper substrate 22). A segment electrode (display electrode) 24 having a shape such as a desired character or figure is provided on one surface side of the upper substrate 22 (the side facing the lower substrate 21).

The lower alignment film 25 is provided on one surface side of the lower substrate 21 so as to cover the common electrode 23. Similarly, the upper alignment film 26 is provided on one surface side of the upper substrate 22 so as to cover the segment electrode 24. As these alignment films 25 and 26, vertical alignment films that regulate the alignment state of the liquid crystal layer 27 in the vertical orientation (substrate normal direction) are used. The uniaxial alignment treatment such as the rubbing treatment is applied to each alignment film so as to be antiparallel to each other (the directions of the uniaxial alignment treatment are indicated by arrows 25r and 26r in the drawing).

The liquid crystal layer 27 is provided between the lower substrate 21 and the upper substrate 22 so as to be surrounded by a frame-shaped sealing material (not shown). The liquid crystal member constituting the liquid crystal layer 27 is filled in the space defined by the lower substrate 21, the upper substrate 22, and the frame-shaped sealing material. As the liquid crystal material, for example, a negative liquid crystal material manufactured by Merck & Co., Inc. (birefringence Δn = 0.08, permittivity anisotropy Δε = −5.0) can be used.

When no voltage is applied, the orientation direction of the liquid crystal molecules constituting the liquid crystal layer 27 is substantially perpendicular to the substrate surfaces of the lower substrate 21 and the upper substrate 22. The pretilt angle of the liquid crystal molecules is about 89.70 °. In the figure, the liquid crystal molecule orientation direction is indicated by an arrow 27d. When a voltage is applied, the orientation direction of the liquid crystal molecules is substantially horizontal to the substrate surfaces of the lower substrate 21 and the upper substrate 22.

The first liquid crystal cell 10 is driven by, for example, a 1/64 Duty, 1/9 Bias multiplex drive having a drive voltage of 22.5 V and a frame frequency of 150 Hz. Further, the second liquid crystal cell 20 is driven by, for example, a 1/4 Duty, 1/3 Bias multiplex drive having a drive voltage of 5 V and a frame frequency of 128 Hz.

The first and second liquid crystal cells 10 and 20 are arranged so that the liquid crystal molecular orientation directions 17d and 27d face the same in-plane direction (including the orientation). The pair of polarizing plates 31 and 32 are arranged so that their absorption axes are orthogonal to each other (cross Nicol arrangement). Further, their absorption axes are arranged so as to be tilted by 45 ° with respect to the liquid crystal molecule orientation direction of the liquid crystal cells 10 and 20.

FIG. 1B is a plan view of the liquid crystal display device 110 as viewed from the front side polarizing plate 32 side. When the first liquid crystal cell is driven (voltage applied state), a dot matrix pattern in which a plurality of pixels are arranged in a matrix can be displayed near the center of the display area. Further, when the second liquid crystal cell is driven (voltage applied state), a segment pattern such as a predetermined character or figure can be displayed in a desired area of the display area. A dot matrix pattern by the first liquid crystal cell and a segment pattern by the second liquid crystal cell can be selectively displayed in the area Asm surrounded by the broken line, which is shown near the center of the display area.

In the liquid crystal display device 110, the dot matrix pattern by the first liquid crystal cell can be displayed in the area Asm, and the segment pattern by the second liquid crystal cell can be displayed in the other (both ends) area. Since the first and second liquid crystal cells have different manufacturing conditions (cell thickness, liquid crystal material) and driving conditions, their optical characteristics (particularly light transmittance) are different. Therefore, when the dot matrix pattern by the first liquid crystal cell and the segment pattern by the second liquid crystal cell are displayed at the same time, a remarkable difference in brightness and brightness may occur between the patterns. Such a difference in brightness and brightness is preferably suppressed from the viewpoint of improving display quality.

FIG. 2A is a cross-sectional view showing how the light transmittance of the first and second liquid crystal cells is measured when the first and second liquid crystal cells are tilted, respectively. The liquid crystal cells 10 and 20 shown in FIG. 2A are shown in a simplified manner for convenience.

The liquid crystal cell is tilted (rotated) around the optical axis 41 of the light source 40 and the axis orthogonal to the liquid crystal molecular orientation direction of the liquid crystal cell (the axis extending from the front to the back in the figure) of the liquid crystal cell. The light transmittance is measured and observed from the front side polarizing plate 32 side. The posture / mode when the liquid crystal cell faces the light source 40 (orthogonal to the optical axis 41 of the light source 40) is used as a reference (observation angle θ = 0 °). The direction in which the liquid crystal cells 10 and 20 are tilted (rotated clockwise in the drawing) so that the liquid crystal molecule orientation direction faces the light source 40 side is set to the positive rotation direction.

FIG. 2B is a graph showing the light transmittance of the second liquid crystal cell (front side liquid crystal cell) 20 when a voltage is applied (transmissive state) when the second liquid crystal cell (front side liquid crystal cell) 20 is tilted from −60 ° to + 60 °. .. The horizontal axis represents the tilt angle θ of the second liquid crystal cell 20, and the vertical axis represents the light transmittance of the liquid crystal cell.

When the inclination of the second liquid crystal cell 20 is 0 °, the light transmittance of the liquid crystal cell is about 13%. When the liquid crystal cell is tilted (rotated) in the positive direction, the light transmittance monotonically increases until the tilt reaches about 40 °. On the other hand, when the liquid crystal cell is tilted (rotated) in the negative direction, the light transmittance monotonically decreases until the tilt reaches about −30 °.

FIG. 2C is a graph showing the light transmittance of the first liquid crystal cell (back side liquid crystal cell) 10 when a voltage is applied (transmissive state) when the first liquid crystal cell (back side liquid crystal cell) 10 is tilted from −60 ° to + 60 °. .. The horizontal axis represents the tilt angle θ of the first liquid crystal cell 10, and the vertical axis represents the light transmittance of the liquid crystal cell.

When the inclination of the first liquid crystal cell 10 is 0 °, the light transmittance of the liquid crystal cell is about 10%. When the liquid crystal cell is tilted (rotated) in the positive direction, the light transmittance monotonically increases until the tilt reaches about 30 °. On the other hand, when the liquid crystal cell is tilted (rotated) in the negative direction, the light transmittance monotonically decreases until the tilt reaches about −20 °.

From the graphs shown in FIGS. 2B and 2C, it can be seen that the light transmittance changes by tilting the liquid crystal cell. In the liquid crystal display device 110 (FIG. 1A) according to the reference example, when the dot matrix pattern by the first liquid crystal cell 10 and the segment pattern by the second liquid crystal cell 20 are displayed side by side, the inclinations of the liquid crystal cells 10 and 20 are adjusted. Therefore, the brightness and brightness of the patterns displayed by these liquid crystal cells can be made equal.

FIG. 3A is a cross-sectional view showing the liquid crystal display device 101 according to the first embodiment. Compared with the reference example (FIG. 1A), in the liquid crystal display device 101, the first liquid crystal cell 10 is arranged at an inclination of, for example, + 5 °. As a result, the light transmittances of the first and second liquid crystal cells 10 and 20 become the same, and as a result, the brightness and brightness of the patterns displayed by the liquid crystal cells become the same.

FIG. 3B is a cross-sectional view showing the liquid crystal display device 102 according to the second embodiment. In the liquid crystal display device 102, in addition to the first liquid crystal cell 10, the second liquid crystal cell 20 is also tilted and arranged. For example, the first liquid crystal cell 10 is tilted by + 10 ° and the second liquid crystal cell 20 is tilted by + 5 °. As a result, the display patterns of both the liquid crystal cells 10 and 20 can be displayed brighter than in the reference example (FIG. 1A).

FIG. 3C is a cross-sectional view showing the liquid crystal display device 103 according to the third embodiment. In the liquid crystal display device 103, a translucent resin member 50 is further filled between the first and second liquid crystal cells 10 and 20. The translucent resin member 50 has a refractive index (for example, 1.4 to 1.6) equivalent to that of the glass substrates (substrates 11, 12, 21, 22, and FIG. 1A) constituting the liquid crystal cells 10 and 20. For the translucent resin member 50, for example, silicone or the like can be used. The translucent resin member 50 prevents dust and the like from entering between the liquid crystal cells 10 and 20, and contributes to the improvement of display quality. Further, by providing the translucent resin member 50 and removing the air layer between the liquid crystal cells 10 and 20, the refractive index interface between the liquid crystal cell (particularly the glass substrate) and the air layer can be eliminated. As a result, the overall transmittance is improved, and the display brightness and brightness can be improved.

FIG. 3D is a cross-sectional view showing the liquid crystal display device 104 according to the fourth embodiment. In the liquid crystal display device 104, the polarizing plates 31 and 32 are also tilted and arranged in accordance with the first and second liquid crystal cells 10 and 20. More specifically, the back side polarizing plate 31 is attached to the back surface of the first liquid crystal cell 10 via an adhesive layer (not shown), and the front side polarizing plate 32 is attached to the surface of the second liquid crystal cell 20 via an adhesive layer (not shown). It is pasted through layers. Similar to the third embodiment, it prevents dust and the like from entering between the members and contributes to the improvement of display quality. Further, by removing the air layer between the liquid crystal cell (particularly the glass substrate) and the polarizing plate to eliminate the refractive index interface, the overall transmittance can be improved and the display brightness and brightness can be improved. ..

FIG. 4 is a plan view showing a segment pattern displayed by the second liquid crystal cell. It is assumed that the display pattern of the liquid crystal display device according to the embodiment is projected on a screen orthogonal to the optical axis of the light source. When the liquid crystal cell is tilted and arranged as shown in the embodiment, particularly when the liquid crystal cell displaying the segment pattern (second liquid crystal cell) is tilted as in the second and third embodiments. The segment pattern of the liquid crystal cell can be projected on the screen in a trapezoidal shape. In such a case, as shown in FIG. 4, it is preferable to form the segment electrode 24 (see FIG. 1A) so as to correct the distortion in consideration of the distortion at the time of projection.

Similarly, an electrode structure in consideration of distortion during projection may be introduced into the dot matrix electrode pattern of the first liquid crystal cell. Further, depending on the application, correction may be performed so as to emphasize the distortion / deformation of the segment pattern such as the pattern.

Although the present invention has been described above based on Examples, the present invention is not limited thereto. In the embodiment, an example in which the liquid crystal cell is tilted in the direction in which the light transmittance increases is shown, but the liquid crystal cell is tilted in the direction in which the light transmittance decreases (negative direction) depending on the application and purpose of the liquid crystal display device. May be good. Further, three or more liquid crystal cells may be stacked and used, an optical member such as a viewing angle compensation plate or an optical lens, or a movable mechanism for automatically tilting the liquid crystal cell may be additionally provided. When the optical member is provided, an optical matching member such as a translucent resin member may be further provided between the optical member and the liquid crystal cell or the polarizing plate.

The liquid crystal cell may be any liquid crystal cell as long as its optical characteristics (particularly light transmittance) change when tilted. For example, instead of the VA drive system, a so-called IPS (inplane switching) drive system liquid crystal cell may be used. In addition, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

10 ... 1st liquid crystal cell (back side liquid crystal cell), 11, 12 ... substrate, 13, 14 ... electrode (dot matrix type), 15, 16 ... alignment film, 17 ... liquid crystal layer, 20 ... second liquid crystal cell (20 ... second liquid crystal cell ( Front side liquid crystal cell), 21,22 ... substrate, 23,24 ... electrode (segment type), 25,26 ... alignment film, 27 ... liquid crystal layer, 31,32 ... polarizing plate, 40 ... light source, 41 ... optical axis, 50 ... Resin member, 101-104 ... Liquid crystal display device according to an embodiment, 110 ... Liquid crystal display device according to a reference example.

Claims (6)

Light source and
A pair of polarizing plates arranged apart from each other on the optical axis of the light source,
A first liquid crystal cell arranged between the pair of polarizing plates and tilted at a first angle with respect to a virtual plane orthogonal to the optical axis of the light source.
A second liquid crystal cell arranged between the pair of polarizing plates,
Have,
The first liquid crystal cell includes a first substrate and a second substrate arranged to face each other, and a first liquid crystal layer sandwiched between the first substrate and the second substrate.
The first substrate and the second substrate are provided with an alignment film that has been subjected to a uniaxial alignment process that is antiparallel to each other.
When no voltage is applied, the first liquid crystal layer is oriented in the first direction.
The second liquid crystal cell includes a third substrate and a fourth substrate arranged to face each other, and a second liquid crystal layer sandwiched between the third substrate and the fourth substrate.
The third substrate and the fourth substrate are provided with an alignment film that has been subjected to a uniaxial alignment process that is antiparallel to each other.
When no voltage is applied, the second liquid crystal layer is oriented in the second direction.
The orientation treatment of the alignment film of the first substrate and the alignment film of the third substrate are the same, and the orientation treatment of the alignment film of the second substrate and the alignment film of the fourth substrate are the same.
When viewed from one side of the pair of polarizing plates, the first and second liquid crystal cells are arranged so that the liquid crystal molecular orientation directions are the same.
Liquid crystal display device. Light source and
A pair of polarizing plates arranged apart from each other on the optical axis of the light source,
A first liquid crystal cell arranged between the pair of polarizing plates and tilted at a first angle with respect to a virtual plane orthogonal to the optical axis of the light source.
A second liquid crystal cell arranged between the pair of polarizing plates,
Have,
The second liquid crystal cell is a liquid crystal display device that tilts with respect to the virtual plane in the same direction as the first liquid crystal cell at a second angle different from the first angle. The liquid crystal display device according to claim 1 or 2, further comprising a translucent resin member that fills the gaps between the first and second liquid crystal cells. The liquid crystal display device according to any one of claims 1 to 3, wherein one of the pair of polarizing plates is attached to the first liquid crystal cell and the other is attached to the second liquid crystal cell. The liquid crystal display device according to any one of claims 1 to 4, wherein the first or second liquid crystal cell is a vertically oriented liquid crystal cell. A pair of polarizing plates arranged apart from each other,
It has first and second liquid crystal cells arranged between the pair of polarizing plates.
The first liquid crystal cell includes a first substrate and a second substrate arranged to face each other, and a first liquid crystal layer sandwiched between the first substrate and the second substrate.
The first substrate and the second substrate are provided with an alignment film that has been subjected to a uniaxial alignment process that is antiparallel to each other.
When no voltage is applied, the first liquid crystal layer is oriented in the first direction.
The second liquid crystal cell includes a third substrate and a fourth substrate arranged to face each other, and a second liquid crystal layer sandwiched between the third substrate and the fourth substrate.
The third substrate and the fourth substrate are provided with an alignment film that has been subjected to a uniaxial alignment process that is antiparallel to each other.
When no voltage is applied, the second liquid crystal layer is oriented in the second direction.
The first liquid crystal cell is arranged so as to be inclined with respect to the second liquid crystal cell.
When viewed from one side of the pair of polarizing plates, the first and second liquid crystal cells are arranged so that the liquid crystal molecular orientation directions are the same.
LCD module.

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