JP2020126199A - Viewing angle control device and display - Google Patents

Abstract

To provide a viewing angle control device that can control a viewing angle, and a display.SOLUTION: A viewing angle control device comprises: a first polarizing plate PL1 that has a first transmission easy axis; a second polarizing plate PL2 that has a second transmission easy axis; and a viewing angle control panel VP. The viewing angle control panel VP has a first substrate 11, a first electrode 12, a first orientation film 13, a second substrate 15, a second electrode 16, a second orientation film 17, and a liquid crystal layer 19. The liquid crystal layer 19 is switched to any one of a first state where the major axis of each of the liquid crystal molecules becomes parallel to a reference axis in plan view and the major axis forms a first inclination angle, and a second state where the major axis of each of the liquid crystal molecules becomes parallel to the reference axis in plan view and the major axis forms a second inclination angle larger than the first inclination angle.SELECTED DRAWING: Figure 3

Description

Embodiments of the present invention relate to a viewing angle control device and a display device.

In recent years, display devices have been applied to various products such as laptop computers, monitors, car navigations, scientific calculators, small and medium TVs, large TVs, mobile phones, and electronic notebooks. Among these products, the display devices used for electronic notebooks, personal digital assistants (PDAs), mobile phones, tablet PCs (PCs), notebook PCs, etc. are light, thin, small, and small, so they are often used by being carried. In addition, display devices for products for ATM (automated teller machine) applications and ticket vending machine applications are often used in public places.

In the above-mentioned products, it may be troublesome for others to identify the displayed contents depending on the usage situation. For example, it is a case where private contents are displayed in a public place on a mobile phone, PDA, or tablet PC. In such a case, it is desirable that the display device has a narrow viewing angle characteristic. However, it is desired that the display device has a function of controlling the viewing angle because a plurality of people may observe the display image. Not limited to this, it is desired that mobile devices and public information terminal devices also have a function of controlling the viewing angle.

International Publication No. 2008/114677 JP-A-6-59287

This embodiment provides a viewing angle control device and a display device capable of controlling the viewing angle.

The viewing angle control device according to one embodiment,
A first polarizing plate having a first easy transmission axis orthogonal to the reference axis, a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate, and the first polarization A first substrate located between the plate and the second polarizing plate, a first electrode located between the first substrate and the second polarizing plate, and a first alignment axis parallel to the reference axis. Having a first alignment film located between the first electrode and the second polarizing plate, a second substrate located between the second polarizing plate and the first alignment film, and the second substrate A second electrode located between the second alignment film and the first alignment film, and a second alignment film having a second alignment axis parallel to the reference axis and located between the second electrode and the first alignment film. And a liquid crystal layer having a liquid crystal material containing a plurality of liquid crystal molecules and a dichroic dye containing a plurality of dichroic dye molecules and located between the first alignment film and the second alignment film. A viewing angle control panel, wherein the liquid crystal layer has a major axis of each of the liquid crystal molecules parallel to the reference axis in plan view, and the major axis forms a first tilt angle with respect to the reference axis. In the first state, the major axis of each of the liquid crystal molecules is parallel to the reference axis in plan view, and the major axis forms a second tilt angle with respect to the reference axis that is larger than the first tilt angle. 2 states,
It is switched to either one of.

Further, the display device according to one embodiment,
A first polarizing plate having a first easy transmission axis orthogonal to the reference axis, a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate, and the first polarization A first substrate located between the plate and the second polarizing plate, a first electrode located between the first substrate and the second polarizing plate, and a first alignment axis parallel to the reference axis. Having a first alignment film located between the first electrode and the second polarizing plate, a second substrate located between the second polarizing plate and the first alignment film, and the second substrate A second electrode located between the second alignment film and the first alignment film, and a second alignment film having a second alignment axis parallel to the reference axis and located between the second electrode and the first alignment film. And a liquid crystal layer having a liquid crystal material containing a plurality of liquid crystal molecules and a dichroic dye containing a plurality of dichroic dye molecules and located between the first alignment film and the second alignment film. A polarizing plate provided with a viewing angle control panel and a display panel for displaying an image, wherein the polarizing plate positioned between the viewing angle control panel and the display panel is one of the first polarizing plate and the second polarizing plate. On the other hand, the liquid crystal layer has a first state in which a long axis of each of the liquid crystal molecules is parallel to the reference axis in a plan view, and the long axis forms a first tilt angle with respect to the reference axis, A second state in which the major axis of each of the liquid crystal molecules is parallel to the reference axis in a plan view, and the major axis forms a second tilt angle with respect to the reference axis that is larger than the first tilt angle;
It is switched to either one of.

FIG. 1 is a cross-sectional view showing the display device according to the first embodiment. FIG. 2 is a cross-sectional view showing the display panel shown in FIG. FIG. 3 is a cross-sectional view showing the viewing angle control panel, the first polarizing plate, and the second polarizing plate shown in FIG. FIG. 4 is an exploded perspective view showing the second polarizing plate, the liquid crystal layer of the viewing angle control panel, and the first polarizing plate. FIG. 5 is a cross-sectional view showing a part of the display panel, the first polarizing plate, and the second polarizing plate, showing a state where no voltage is applied to the liquid crystal layer. FIG. 6 is a plan view showing the liquid crystal layer shown in FIG. FIG. 7 is a cross-sectional view showing a part of the display panel, the first polarizing plate, and the second polarizing plate, and is a diagram showing a state in which a voltage is applied to the liquid crystal layer. FIG. 8 is a plan view showing the liquid crystal layer shown in FIG. FIG. 9 is a graph showing changes in the contrast ratio with respect to an angle inclined from the front direction of the screen of the display device in each case where the guest content in the liquid crystal layer is 0%, 1%, 2%, and 3%. FIG. FIG. 10 is a graph showing a change in the contrast ratio with respect to the content when the angle is 50°. FIG. 11: is a figure which shows the graph of the change of the transmittance|permeability of the light with respect to the said angle in each case where the said content is 1%, 2%, and 3%. FIG. 12 is a plot diagram showing a change in light transmittance with respect to the content in the front direction (the angle=0°). FIG. 13 is a graph showing a change in brightness with respect to a voltage applied to the liquid crystal layer when the angle is 50° in the first embodiment and the comparative example 2. FIG. 14 is a graph showing a change in the brightness level with respect to the angle when the voltage is 4 V in the first embodiment and the comparative example 2. FIG. 15 is a cross-sectional view showing the viewing angle control panel, the first polarizing plate, and the second polarizing plate of the display device according to the first modification of the first embodiment. FIG. 16 is a cross-sectional view showing the viewing angle control panel, the first polarizing plate, the second polarizing plate, the third polarizing plate, and the fourth polarizing plate of the display device according to the modified example 3 of the first embodiment. .. FIG. 17 is a sectional view showing the display device according to the second embodiment.

Hereinafter, each embodiment and each modification of the present invention will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and a person skilled in the art can easily think of appropriate modifications while keeping the gist of the invention, of course, is included in the scope of the invention. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part as compared with the actual mode, but this is merely an example, and the interpretation of the present invention will be understood. It is not limited. In the specification and the drawings, the same elements as those described above with reference to the already-explained drawings are designated by the same reference numerals, and detailed description thereof may be appropriately omitted.

(First embodiment)
First, the display device DSP according to the first embodiment will be described. FIG. 1 is a sectional view showing a display device DSP according to the first embodiment.
As shown in FIG. 1, the display device DSP includes a first polarizing plate PL1, a second polarizing plate PL2, a viewing angle control panel VP, a display panel PNL for displaying an image, a third polarizing plate PL3, and an illumination. It is provided with a device BU and a control unit CON.

The second polarizing plate PL2 is arranged to face the first polarizing plate PL1. The viewing angle control panel VP is arranged between the first polarizing plate PL1 and the second polarizing plate PL2. The display panel PNL is arranged to face the viewing angle control panel VP. The polarizing plate located between the viewing angle control panel VP and the display panel PNL is either the first polarizing plate PL1 or the second polarizing plate PL2. In the present embodiment, the polarizing plate located between the viewing angle control panel VP and the display panel PNL is the second polarizing plate PL2. The display panel PNL is located between the second polarizing plate PL2 and the third polarizing plate PL3. The first polarizing plate PL1 is located between the lighting device BU and the viewing angle control panel VP.

The control unit CON is electrically connected to each of the viewing angle control panel VP, the display panel PNL, and the lighting device BU, and controls the driving of each of the viewing angle control panel VP, the display panel PNL, and the lighting device BU. Is configured.

The lighting device BU of the present embodiment is a backlight unit. The lighting device BU emits diffused light. The viewing angle control panel VP has a first state in which light incident from the illumination device BU side together with the first polarizing plate PL1 and the second polarizing plate PL2 is emitted as diffused light, and a second state in which light is condensed and emitted. , Or one of them. It should be noted that the above-mentioned light collection and emission means that light is collected and emitted in the normal direction of the surface of the second polarizing plate PL2 on the display panel PNL side.

Diffused light or light having a higher directivity than the diffused light is incident on the display panel PNL. When the diffused light enters the display panel PNL, the display device DSP widens the viewing angle θ and displays an image. On the other hand, when light having a higher directivity than the diffused light enters the display panel PNL, the display device DSP narrows the viewing angle θ and displays an image. Here, the direction in which the first polarizing plate PL1, the viewing angle control panel VP, and the second polarizing plate PL2 are arranged and orthogonal to the reference axis RA is the front direction of the display device DSP. When the display device DSP is arranged so that the reference axis RA extends vertically, the viewing angle θ is the angle of the left and right effective fields of view toward the screen. The viewing angle θ in the front direction is 0°. In the present embodiment, the viewing angle θ on the left side of the front direction is represented as positive (+θ), and the viewing angle θ on the right side of the front direction is represented as negative (−θ).

The first polarizing plate PL1, the viewing angle control panel VP, the second polarizing plate PL2, the display panel PNL, and the third polarizing plate PL3 are adhered by an adhesive layer interposed therebetween. However, an adhesive layer may not be interposed between the first polarizing plate PL1, the viewing angle control panel VP, the second polarizing plate PL2, the display panel PNL, and the third polarizing plate PL3, and an air layer may be interposed. You may have.
The first polarizing plate PL1, the second polarizing plate PL2, the viewing angle control panel VP, and the control unit CON of the display device DSP configure a viewing angle control device.

Next, the configuration of the display panel PNL will be described. FIG. 2 is a sectional view showing the display panel PNL shown in FIG.
As shown in FIGS. 1 and 2, the display panel PNL is a transmissive liquid crystal display panel. Therefore, the display device DSP of this embodiment is a liquid crystal display device. The display panel PNL is a transmissive liquid crystal display panel, and is located between the second polarizing plate PL2 and the third polarizing plate PL3. The display panel PNL includes an array substrate 20, a counter substrate 30 which is arranged to face the array substrate 20 with a gap therebetween, and a liquid crystal layer 40 which is held between the array substrate 20 and the counter substrate 30. ..

The array substrate 20 has a transparent insulating substrate 21. On the insulating substrate 21, a plurality of thin film transistors 22 as switching elements, a plurality of pixel electrodes 23, an alignment film 26 and the like are provided. The counter substrate 30 has a transparent insulating substrate 31. A color filter 50, a counter electrode 32, and an alignment film 33 are provided on the side of the insulating substrate 31 facing the array substrate 20. The color filter 50 includes a light shielding portion 51, a peripheral light shielding portion 52, and a plurality of colored layers 53, 54, 55 of red, green and blue. The spacer 25 holds the gap between the array substrate 20 and the counter substrate 30. The array substrate 20 and the counter substrate 30 are joined to each other by a sealing material 41 arranged on the peripheral portions of both substrates. The liquid crystal layer 40 is held between the array substrate 20 and the counter substrate 30 and is surrounded by the sealing material 41.

Next, the configurations of the first polarizing plate PL1, the viewing angle control panel VP, and the second polarizing plate PL2 will be described. FIG. 3 is a cross-sectional view showing the viewing angle control panel VP, the first polarizing plate PL1 and the second polarizing plate PL2 shown in FIG. FIG. 4 is an exploded perspective view showing the second polarizing plate PL2, the liquid crystal layer 19 of the viewing angle control panel VP, and the first polarizing plate PL1.

As shown in FIGS. 3 and 4, the first polarizing plate PL1 has a first absorption axis A1a parallel to the reference axis RA. The first polarizing plate PL1 is a linear polarizing plate. The first easy axis A1b of the first polarizing plate PL1 is orthogonal to the first absorption axis A1a. The second polarizing plate PL2 has a second absorption axis A2a parallel to the reference axis RA. The second polarizing plate PL2 is a linear polarizing plate. The second easy axis A2b of the second polarizing plate PL2 is orthogonal to the second absorption axis A2a. The third polarizing plate PL3 (FIG. 1) has a third easy axis of transmission and a third absorption axis in a predetermined direction based on the display mode of the display panel PNL.

The viewing angle control panel VP has a first substrate 11, a first electrode 12, a first alignment film 13, a second substrate 15, a second electrode 16, a second alignment film 17, and a liquid crystal layer 19.
The first substrate 11 is located between the first polarizing plate PL1 and the second polarizing plate PL2. The first substrate 11 is formed of a transparent insulating substrate such as glass or resin. The first electrode 12 is located between the first substrate 11 and the second polarizing plate PL2. In the present embodiment, the first electrode 12 is formed on the first substrate 11. The first electrode 12 is formed of a transparent conductive material such as ITO (indium tin oxide). Further, the first electrode 12 is formed on the first substrate 11. The first alignment film 13 is located between the first electrode 12 and the second polarizing plate PL2. In the present embodiment, the first alignment film 13 is formed on the first electrode 12 and is in contact with the liquid crystal layer 19. The first alignment film 13 has a first alignment axis AA1 parallel to the reference axis RA.

The second substrate 15 is located between the second polarizing plate PL2 and the first alignment film 13. The second substrate 15 is formed of a transparent insulating substrate such as glass or resin. The second electrode 16 is located between the second substrate 15 and the first alignment film 13. In the present embodiment, the second electrode 16 is formed on the side of the second substrate 15 that faces the first alignment film 13. The second electrode 16 is formed of a transparent conductive material such as ITO. The second alignment film 17 is located between the second electrode 16 and the first alignment film 13. In the present embodiment, the second alignment film 17 is provided on the side of the second electrode 16 facing the first alignment film 13 and is in contact with the liquid crystal layer 19. The second alignment film 17 has a second alignment axis AA2 parallel to the reference axis RA.

The liquid crystal layer 19 is located between the first alignment film 13 and the second alignment film 17. The liquid crystal layer 19 has a liquid crystal material containing a plurality of liquid crystal molecules M1 and a dichroic dye containing a plurality of dichroic dye molecules M2. In other words, the liquid crystal layer 19 is formed by adding a dichroic dye to a liquid crystal material. In this embodiment, the concentration of the dichroic dye in the liquid crystal layer 19 is 2%. In other words, the content of the dichroic dye is 2%. In the present embodiment, the dichroic dye (dichroic dye) is G472. However, G472 is an example of a dichroic dye, and the dichroic dye is not limited to G472.

The liquid crystal molecule M1 has a long axis LA. The dichroic dye molecule M2 is a compound having a rod-like structure like the liquid crystal molecule M1. The liquid crystal molecules M1 are initially aligned by the alignment regulating force of the first alignment film 13 and the second alignment film 17. The control unit CON is configured to control driving of the first electrode 12 and the second electrode 16, for example. When a voltage is applied between the first electrode 12 and the second electrode 16, the electric field (longitudinal electric field) applied to the liquid crystal layer 19 controls the alignment direction of the liquid crystal molecules M1. The dichroic dye molecules M2 are aligned in the same direction as the liquid crystal molecules M1. Therefore, the direction of the dichroic dye molecule M2 changes with the switching of the liquid crystal molecule M1. From the above, the viewing angle control panel VP is composed of a guest-host mode liquid crystal panel.

In the present embodiment, the arrangement direction da of the plurality of liquid crystal molecules M1 is uniform in the state where the voltage is not applied between the first electrode 12 and the second electrode 16 (first state). In other words, the long axes LA of the plurality of liquid crystal molecules M1 are substantially aligned in one direction in the first state.

Next, the state where no voltage is applied to the liquid crystal layer 19 of the viewing angle control panel VP will be described. FIG. 5 is a cross-sectional view showing a part of the display panel PNL, the first polarizing plate PL1, and the second polarizing plate PL2, and is a diagram showing a state where no voltage is applied to the liquid crystal layer 19. The liquid crystal layer 19 shown in FIG. 5 has been switched to the first state. FIG. 6 is a plan view showing the liquid crystal layer 19 shown in FIG. In addition, in FIG. 6, the liquid crystal layer 19 is viewed from the second polarizing plate PL2 side.

As shown in FIGS. 5 and 6, the first alignment film 13 and the second alignment film 17 are horizontal alignment films, respectively. An alignment treatment is applied to each of the first alignment film 13 and the second alignment film 17. In the present embodiment, the first alignment film 13 is rubbed in the first direction d1 that is parallel to the first alignment axis AA1. The second alignment film 17 is rubbed in a second direction d2 that is parallel to the second alignment axis AA2 and is opposite to the first direction d1. The liquid crystal layer 19 has a positive dielectric anisotropy. Therefore, the liquid crystal layer 19 has a homogeneous alignment in the first state.

In plan view, the long axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA (FIG. 6). The long axis LA of each liquid crystal molecule M1 forms a first tilt angle φ1 with respect to the reference axis RA. In the first state, the first tilt angle φ1 of the liquid crystal molecules M1 near the first alignment film 13, the first tilt angle φ1 of the liquid crystal molecules M1 near the second alignment film 17, and the first alignment film of the liquid crystal layer 19 13 and the first tilt angle φ1 of the liquid crystal molecule M1 of the intermediate layer located between the second alignment film 17 and the second alignment film 17 are substantially the same.
By switching the viewing angle control panel VP to the first state as described above, the display device DSP can widen the viewing angle θ and display an image.

Next, a state in which a voltage is applied to the liquid crystal layer 19 of the viewing angle control panel VP will be described. FIG. 7 is a cross-sectional view showing a part of the display panel PNL, the first polarizing plate PL1, and the second polarizing plate PL2, and is a diagram showing a state in which a voltage is applied to the liquid crystal layer 19. The liquid crystal layer 19 shown in FIG. 7 is switched to the second state. FIG. 8 is a plan view showing the liquid crystal layer 19 shown in FIG. In addition, in FIG. 8, the liquid crystal layer 19 is viewed from the second polarizing plate PL2 side.

As shown in FIGS. 7 and 8, in the liquid crystal layer 19 in the second state, the liquid crystal molecules M1 have an alignment regulating force by the first alignment film 13 and the second alignment film 17, and an electric field applied to the liquid crystal layer 19. And are working. In plan view, the long axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA (FIG. 8). Further, the major axis LA of each liquid crystal molecule M1 forms a second tilt angle φ2 with respect to the reference axis RA that is larger than the first tilt angle φ1.

The liquid crystal molecules M1 in the middle layer of the liquid crystal layer 19 are less affected by the alignment regulating force than the liquid crystal molecules M1 near the first alignment film 13 and the liquid crystal molecules M1 near the second alignment film 17. Therefore, of the second tilt angle φ2 in the second state, the second tilt angle φ2 of the liquid crystal molecule M1 of the intermediate layer is the largest. From the viewpoint of narrowing the viewing angle θ, when the liquid crystal layer 19 is switched to the second state, the second tilt angle φ2 in the liquid crystal molecule M1 is preferably more than 60° and less than 90° (60°). <φ2<90°). In other words, the control unit CON adjusts the voltage applied between the first electrode 12 and the second electrode 16 (voltage applied to the liquid crystal layer 19) so that the second tilt angle φ2 does not exceed 90°. Is desirable.
By switching the liquid crystal layer 19 to the second state as described above, the display device DSP can display an image with a narrow viewing angle θ.

Next, regarding the contrast characteristics, the dependence of the viewing angle θ and the concentration of the guest (dichroic dye) will be described. FIG. 9 is a graph showing changes in the contrast ratio with respect to the viewing angle θ when the guest concentration in the liquid crystal layer 19 is 0%, 1%, 2%, and 3%. FIG. 10 is a graph showing a change in the contrast ratio with respect to the concentration of the guest when the viewing angle θ is 50°.

Here, a display device in which the guest concentration in the liquid crystal layer 19 is 0% will be described as the display device of Comparative Example 1. Further, the contrast ratio shown in FIGS. 9 and 10 refers to the ratio of the brightness of the light emitted from the second polarizing plate PL2 when the liquid crystal layer 19 is switched between the first state and the second state. Various display devices including the display device DSP of the present embodiment and the display device of Comparative Example 1 differ only in the concentration of the guest in the liquid crystal layer 19, but have the same configuration except the concentration of the guest.

As shown in FIG. 9, it can be seen that the contrast ratio is substantially 1 within the range of approximately |θ|<20°. Therefore, even if the liquid crystal layer 19 is switched from the first state to the second state in the front direction of the screen, it is possible to suppress the decrease in the brightness level of the image.
Further, the contrast ratio can be increased within a range of approximately 40°<|θ|<70°. For example, at |θ|=50°, high contrast can be obtained. Therefore, it can be seen that the viewing angle θ becomes narrower by switching the liquid crystal layer 19 to the second state.

Further, it can be seen that the contrast characteristic depends not only on the viewing angle θ but also on the concentration of the guest (dichroic dye). When the guest is added to the liquid crystal layer 19, the contrast ratio can be increased as compared with the case where the guest is not added to the liquid crystal layer 19. Further, the contrast ratio can be increased as the amount of guest added to the liquid crystal layer 19 is increased. For example, at |θ|=50°, the contrast ratio was substantially the same when the guest concentration in the liquid crystal layer 19 was 2% and when it was 3%. The viewing angle control based on birefringence interference can improve the performance by making the liquid crystal layer 19 into a guest host.

As shown in FIG. 10, at |θ|=50°, the contrast ratio does not increase to the right. It can be seen that the contrast ratio reaches a peak when the guest concentration is set to 2%, and the contrast ratio does not increase even if the guest concentration is changed from 2% to 3%.

Next, the dependence of the light transmittance on the viewing angle θ and the concentration of the guest (dichroic dye) will be described. FIG. 11 is a graph showing changes in the light transmittance with respect to the viewing angle θ when the guest concentrations in the liquid crystal layer 19 are 1%, 2%, and 3%, respectively. FIG. 12 is a plot diagram showing changes in the light transmittance with respect to the concentration of the guest in the liquid crystal layer 19 in the front direction (θ=0°) of the screen. 11 and 12, the light transmittance of the display device of Comparative Example 1 is set to 1, and the light transmittance is normalized.

As shown in FIG. 11, it can be seen that the light transmittance decreases as the guest addition amount to the liquid crystal layer 19 increases, regardless of the range of the viewing angle θ.
As shown in FIG. 12, it can be seen that the light transmittance decreases downward to the right in the front direction of the screen (θ=0°).

As described above, based on the description of FIGS. 9 to 12, the concentration of the dichroic dye in the liquid crystal layer 19 is preferably in the range of 1 to 3% from the viewpoint of viewing angle characteristics. More preferably, the concentration is within the range of 2 to 3%. More preferably, the concentration is 2%.

Next, the dependence of the voltage applied to the liquid crystal layer 19 on the brightness (light transmittance) will be described. FIG. 13 is a graph showing a change in brightness with respect to a voltage applied to the liquid crystal layer 19 when |θ| is 50° in the present embodiment and Comparative Example 2. The display device of Comparative Example 2 is different from the display device of the present embodiment in that the viewing angle control panel VP is located closer to the screen side of the display device than the third polarizing plate PL3, and the display device is configured without the second polarizing plate PL2. The display device DSP is different from that of the embodiment.

As shown in FIG. 13, at |θ|=50°, the brightness of the image can be increased by setting the voltage applied to the liquid crystal layer 19 to 0 V, and a slight voltage is applied to the liquid crystal layer 19. Therefore, it can be seen that the brightness of the image can be reduced. In order to reduce the brightness of the image, the voltage applied to the liquid crystal layer 19 is preferably within the range of 3 to 7V. Therefore, the control unit applies a voltage of 0 V between the first electrode 12 and the second electrode 16 when the liquid crystal layer 19 is switched to the first state, and when the liquid crystal layer 19 is switched to the second state. It is preferable to apply a voltage within the range of 3 to 7 V between the first electrode 12 and the second electrode 16. From the viewpoint of contrast characteristics (viewing angle characteristics), when the liquid crystal layer 19 is switched to the second state, the voltage applied between the first electrode 12 and the second electrode 16 is within the range of 3.5 to 5V. Is more desirable. From the above, in the present embodiment, the viewing angle θ can be changed efficiently with a low voltage.

Next, the dependence of the viewing angle θ on the brightness level (light transmittance) will be described. FIG. 14 is a graph showing a change in the luminance level with respect to the viewing angle θ when the voltage applied to the liquid crystal layer 19 is 4V in the present embodiment and the comparative example 2.
As shown in FIG. 14, it can be seen that the viewing angle control of the display device DSP of the present embodiment is superior to the viewing angle control of the display device DSP of Comparative Example 2. Therefore, as shown in FIG. 1, it is preferable that the viewing angle control device and the display device DSP include the second polarizing plate PL2. In other words, it is preferable that the viewing angle control device and the display device DSP are not configured without the second polarizing plate PL2.

According to the viewing angle control device and the display device DSP according to the first embodiment configured as described above, the display device DSP (viewing angle control device) includes the first absorption axis A1a and the first easy transmission axis A1b. A first polarizing plate PL1 having the same, a second polarizing plate PL2 having a second absorption axis A2a and a second easy transmission axis A2b facing the first polarizing plate PL1, and a field of view composed of a guest-host mode liquid crystal panel. And a corner control panel VP. The viewing angle control panel VP includes a first substrate 11, a first electrode 12, a first alignment film 13 having a first alignment axis AA1, a second substrate 15, a second electrode 16, and a second alignment axis AA2. And a liquid crystal layer 19.

The liquid crystal layer 19 has a liquid crystal material containing a plurality of liquid crystal molecules M1 and a dichroic dye containing a plurality of dichroic dye molecules M2. The liquid crystal layer 19 is switched to either the first state or the second state. The first state is a state in which the long axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA in plan view, and the long axis LA forms a first tilt angle φ1 with respect to the reference axis RA. The second state is a state in which the long axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA in plan view, and the long axis LA forms a second tilt angle φ2 with respect to the reference axis RA.

Therefore, the display device DSP can display an image with a wide viewing angle θ in the first state and display an image with a narrow viewing angle θ in the second state. The viewing angle control device can emit diffused light in the first state, and can collect and emit light in the second state.

Further, the display device DSP of the present embodiment can suppress the decrease in the brightness level of the image in the front direction of the screen. Compared with the display device of Comparative Example 1, the display device DSP of the present embodiment can obtain high contrast in the left and right directions toward the screen. Regarding the viewing angle control, the display device DSP of the present embodiment is superior to the display device DSP of Comparative Example 2.
From the above, it is possible to obtain the viewing angle control device and the display device DSP capable of controlling the viewing angle θ.

(Modification 1 of the first embodiment)
Next, the viewing angle control device and the display device DSP according to the first modification of the first embodiment will be described. FIG. 15 is a cross-sectional view showing the viewing angle control panel VP, the first polarizing plate PL1, and the second polarizing plate PL2 of the display device DSP according to the modified example 1 of the first embodiment.

As shown in FIG. 15, in the display device DSP of the modified example 1, one of the first alignment film 13 and the second alignment film 17 may be a vertical alignment film. In the present modification 1, the first alignment film 13 is a vertical alignment film. The first alignment film 13 is rubbed in the first direction d1. Therefore, in the first state, the long axis LA of the liquid crystal molecules M1 near the first alignment film 13 is not parallel to the normal line of the surface of the first alignment film 13.

In the first state, the first tilt angle φ1 of the liquid crystal molecules M1 near the first alignment film 13 is less than 90°. Further, as in the first embodiment, the major axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA in plan view. The liquid crystal layer 19 has a positive dielectric anisotropy. Therefore, the liquid crystal layer 19 has a hybrid alignment in the first state.
Also in the viewing angle control device and the display device DSP according to the modified example 1 configured as described above, the same effect as that of the first embodiment can be obtained.

(Modification 2 of the first embodiment)
Next, the viewing angle control device and the display device DSP according to the second modification of the first embodiment will be described. Although not shown, the liquid crystal layer 19 may have vertical alignment in the first state. Both the first alignment film 13 and the second alignment film 17 are vertical alignment films. The first alignment film 13 is rubbed in the first direction d1, and the second alignment film 17 is rubbed in the second direction d2. The liquid crystal layer 19 has a negative dielectric anisotropy.
Also in the viewing angle control device and the display device DSP according to the modified example 2 configured as described above, the same effect as in the first embodiment can be obtained.

(Modification 3 of the first embodiment)
Next, a display device DSP according to Modification 3 of the first embodiment will be described. FIG. 16 is a view angle control panel VP, a first polarizing plate PL1, a second polarizing plate PL2, a third polarizing plate PL3, and a fourth polarizing plate PL4 of the display device DSP according to the modified example 3 of the first embodiment. FIG.

As shown in FIG. 16, the display device DSP may further include a fourth polarizing plate PL4. The fourth polarizing plate PL4 is located between the second polarizing plate PL2 and the display panel PNL. The fourth polarizing plate PL4 is a linear polarizing plate and has a fourth absorption axis A4a parallel to the second absorption axis A2a. As in the above-described first embodiment, the viewing angle control panel VP and the display panel PNL may share the single second polarizing plate PL2, but as in the third modification, the viewing angle control panel is used. The polarizing plate used in combination with the VP and the polarizing plate used in combination with the display panel PNL may be separated.
Also in the display device DSP according to the modified example 3 configured as described above, the same effect as that of the first embodiment can be obtained.

(Second embodiment)
Next, the display device DSP according to the second embodiment will be described. FIG. 17 is a sectional view showing a display device DSP according to the second embodiment.
As shown in FIG. 17, the display device DSP includes a first polarizing plate PL1, a second polarizing plate PL2, a viewing angle control panel VP, a display panel PNL for displaying an image, and a control unit CON. There is. The viewing angle control panel VP may be located on the screen side of the display panel PNL. The polarizing plate located between the viewing angle control panel VP and the display panel PNL is the first polarizing plate PL1.

Various self-luminous display panels such as an organic EL (electroluminescent) display panel and a micro LED (light-emitting diode) display panel can be applied to the display panel PNL. Alternatively, various non-self-luminous display panels such as a liquid crystal display panel can be applied to the display panel PNL. In that case, the display device DSP may further include the illumination device BU.
Also in the display device DSP according to the second embodiment configured as described above, the same effect as in the first embodiment can be obtained.

While some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the scope of equivalents thereof.
For example, the viewing angle control panel VP may be composed of a liquid crystal panel in a mode other than the guest-host mode.

DSP...Display device, PNL...Display panel, CON...Control unit,
PL1, PL2, PL3, PL4... Polarizing plates PL, VP... Viewing angle control panel,
11, 15... Substrate, 12, 16... Electrodes, 13, 17... Alignment film, 19... Liquid crystal layer,
M1... Liquid crystal molecule, M2... Dichroic dye molecule, LA... Long axis, RA... Reference axis,
A1a, A2a, A4a... Absorption axis, A1b, A2b... Easy transmission axis,
AA1, AA2... Alignment axis, θ... Viewing angle, φ1, φ2... Inclination angle.

Claims (13)

A first polarizing plate having a first easy transmission axis orthogonal to the reference axis;
A second polarizing plate having a second easy axis of transmission orthogonal to the reference axis and facing the first polarizing plate;
A first substrate positioned between the first polarizing plate and the second polarizing plate, a first electrode positioned between the first substrate and the second polarizing plate, and a first electrode parallel to the reference axis. A first alignment film having a first alignment axis and positioned between the first electrode and the second polarizing plate; and a second substrate positioned between the second polarizing plate and the first alignment film, The second electrode is located between the second substrate and the first alignment film, and has a second alignment axis parallel to the reference axis, and is located between the second electrode and the first alignment film. A liquid crystal layer having a second alignment film, a liquid crystal material containing a plurality of liquid crystal molecules, and a dichroic dye containing a plurality of dichroic dye molecules and located between the first alignment film and the second alignment film. And a viewing angle control panel having
The liquid crystal layer is
A first state in which a long axis of each of the liquid crystal molecules is parallel to the reference axis in a plan view and the long axis forms a first tilt angle with respect to the reference axis
A second state in which the major axis of each of the liquid crystal molecules is parallel to the reference axis in a plan view, and the major axis forms a second tilt angle with respect to the reference axis that is larger than the first tilt angle;
Can be switched to either
Viewing angle control device. The concentration of the dichroic dye in the liquid crystal layer is in the range of 1 to 3%,
The viewing angle control device according to claim 1. The first alignment film and the second alignment film are horizontal alignment films,
The liquid crystal layer has a positive dielectric anisotropy and adopts a homogeneous orientation,
The viewing angle control device according to claim 1. When the liquid crystal layer is switched to the second state, the second tilt angle is more than 60° and less than 90°,
The viewing angle control device according to claim 3. Further comprising a control unit that controls driving of the first electrode and the second electrode,
The control unit is
When the liquid crystal layer is switched to the first state, a voltage of 0V is applied between the first electrode and the second electrode,
When the liquid crystal layer is switched to the second state, a voltage within the range of 3 to 7V is applied between the first electrode and the second electrode.
The viewing angle control device according to claim 3. When the liquid crystal layer is switched to the second state, the voltage is in the range of 3.5 to 5V,
The viewing angle control device according to claim 5. A first polarizing plate having a first easy transmission axis orthogonal to the reference axis;
A second polarizing plate having a second easy axis of transmission orthogonal to the reference axis and facing the first polarizing plate;
A first substrate positioned between the first polarizing plate and the second polarizing plate, a first electrode positioned between the first substrate and the second polarizing plate, and a first electrode parallel to the reference axis. A first alignment film having a first alignment axis and positioned between the first electrode and the second polarizing plate; and a second substrate positioned between the second polarizing plate and the first alignment film, The second electrode is located between the second substrate and the first alignment film, and has a second alignment axis parallel to the reference axis, and is located between the second electrode and the first alignment film. A liquid crystal layer having a second alignment film, a liquid crystal material containing a plurality of liquid crystal molecules, and a dichroic dye containing a plurality of dichroic dye molecules and located between the first alignment film and the second alignment film. And a viewing angle control panel having:
A display panel for displaying an image,
The polarizing plate positioned between the viewing angle control panel and the display panel is one of the first polarizing plate and the second polarizing plate,
The liquid crystal layer is
A first state in which a long axis of each of the liquid crystal molecules is parallel to the reference axis in a plan view, and the long axis forms a first tilt angle with respect to the reference axis;
A second state in which the major axis of each of the liquid crystal molecules is parallel to the reference axis in a plan view, and the major axis forms a second tilt angle with respect to the reference axis that is larger than the first tilt angle;
Can be switched to either
Display device. The concentration of the dichroic dye in the liquid crystal layer is in the range of 1 to 3%,
The display device according to claim 7. The first alignment film and the second alignment film are horizontal alignment films,
The liquid crystal layer has a positive dielectric anisotropy and adopts a homogeneous orientation,
The display device according to claim 7. When the liquid crystal layer is switched to the second state, the second tilt angle is more than 60° and less than 90°,
The display device according to claim 9. Further comprising a control unit that controls driving of the first electrode and the second electrode,
The control unit is
When the liquid crystal layer is switched to the first state, a voltage of 0V is applied between the first electrode and the second electrode,
When the liquid crystal layer is switched to the second state, a voltage within the range of 3 to 7V is applied between the first electrode and the second electrode.
The display device according to claim 9. When the liquid crystal layer is switched to the second state, the voltage is in the range of 3.5 to 5V,
The display device according to claim 11. A third polarizing plate,
And a lighting device,
The polarizing plate located between the viewing angle control panel and the display panel is the second polarizing plate,
The display panel is a transmissive liquid crystal display panel, and is located between the second polarizing plate and the third polarizing plate.
The first polarizing plate is located between the lighting device and the viewing angle control panel,
The display device according to claim 7.

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