WO2008047754A1

WO2008047754A1 - Display and viewing angle control device used for same

Info

Publication number: WO2008047754A1
Application number: PCT/JP2007/070068
Authority: WO
Inventors: Takehiko Sakai; Tsuyoshi Okazaki; Katsuhiko Morishita; Yoshiharu Kataoka; Chikanori Tsukamura
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-10-20
Filing date: 2007-10-15
Publication date: 2008-04-24

Abstract

It is an object to provide a display that can be applied to various use environments or a variety of uses by switching a display state between a wide viewing angle and a narrow viewing angle. A viewing angle control liquid crystal panel of a display device is comprised of a dichroism pigment added liquid crystal layer (23) disposed on a pair of translucent substrates (21a, 21b) and electrodes (24a) arranged on the translucent substrate (21a). A polarizer (12) is set on a light incident side of the viewing angle control liquid crystal panel. When a voltage is applied to the electrode (24a) by a driving circuit, an electric field substantially in parallel with the substrate surface is locally generated at a part of a domain in the liquid crystal layer (23). ON/OFF switches for the driving circuit to apply a voltage to the electrode (24a) cause switches the display state between a first state to provide a first viewing angle range and a second state to provide a second viewing angle range.

Description

Specification

Display and viewing angle control device used therefor

Technical field

The present invention relates to a viewing angle control device capable of switching a viewing angle of a display between a wide viewing angle and a narrow viewing angle, and a display using the viewing angle control device.

Background art

[0002] In general, a display is required to have a viewing angle as wide as possible so that a clear image can be seen from any viewing angle. In particular, liquid crystal displays that have recently become widespread have been developed with respect to wide viewing angles because the liquid crystal itself has a viewing angle dependency. However, depending on the usage environment, it may be advantageous to have a narrow viewing angle so that only the user can see the displayed content. In particular, notebook personal computers, personal digital assistants (PDAs), or mobile phones are highly likely to be used in places where an unspecified number of people can exist, such as in trains and airplanes. In such a usage environment, it is desirable that the viewing angle of the display be narrow because it is not desirable for others to display the display contents from the viewpoint of maintaining confidentiality and protecting privacy. Thus, in recent years, there has been an increasing demand for switching the viewing angle of a single display between a wide viewing angle and a narrow viewing angle depending on usage conditions. This requirement is not limited to liquid crystal displays, but is a common issue for any display.

[0003] In response to such a request, a phase difference control device is provided in addition to a display device that displays an image, and the viewing angle characteristics are changed by controlling the voltage applied to the phase difference control device. A technique has been proposed (see, for example, Japanese Patent No. 3322197). Japanese Patent No. 3322197 exemplifies chiral nematic liquid crystal, homogeneous liquid crystal, randomly aligned nematic liquid crystal, and the like as the liquid crystal mode used in the liquid crystal display device for phase difference control.

[0004] Further, a viewing angle control liquid crystal panel is provided above the display liquid crystal panel, and these panels are sandwiched between two polarizing plates to adjust the voltage applied to the viewing angle control liquid crystal panel. Thus, a configuration for performing viewing angle control has been conventionally disclosed (for example, JP-A-10-268251 and JP-A-2005-316470). In Japanese Patent Laid-Open No. 10-268251, the liquid crystal mode of the viewing angle control liquid crystal panel is a twisted nematic system. Japanese Patent Laid-Open No. 2005-3 16470 discloses a configuration in which a viewing angle control liquid crystal panel is provided between two polarizing plates having parallel transmission axes.

Disclosure of the invention

Problems to be solved by the invention

[0005] In Japanese Patent No. 3322197, it is said that the use of a phase difference controlling liquid crystal element enables switching between a wide viewing angle and a narrow viewing angle, and the effect is not sufficient. For example, FIG. 4 of Japanese Patent No. 3322197 shows an equal contrast curve with a contrast ratio of 10: 1, and the contrast in the wide viewing angle direction certainly decreases at a narrow viewing angle. However, with this level of change, the display can be fully recognized by the next person. In general, even if the contrast ratio decreases to 2: 1, the display can be sufficiently visually recognized.

[0006] The technique disclosed in Japanese Patent Laid-Open No. 10-268251 also switches between a wide viewing angle and a narrow viewing angle by adjusting the contrast by changing the voltage applied to the viewing angle control liquid crystal panel. The effect is not sufficient.

[0007] That is, both the techniques of Japanese Patent No. 3322197 and Japanese Patent Application Laid-Open No. 10-268251 disclose a technique for switching between a wide viewing angle and a narrow viewing angle by reducing the contrast in the wide viewing angle direction. The force S used, such a method, has the problem that an image may be seen by another person who is not sufficiently shielded in the wide viewing angle direction at a narrow viewing angle.

[0008] Therefore, the present invention has been made to solve the above problems, and a display that can be adapted to various usage environments and applications by switching between a wide viewing angle and a narrow viewing angle, and An object of the present invention is to provide a viewing angle control device used in

Means for solving the problem

[0009] In order to achieve the above object, a display according to the present invention includes a display device that is driven according to an image to be displayed, and at least one of a rear surface and a front surface of the display device. A display provided with a viewing angle control device that controls a viewing angle of the display device, the viewing angle control device comprising: a pair of translucent substrates; and at least one of the pair of translucent substrates An electrode provided on one side, an alignment film provided on each of the pair of translucent substrates, a liquid crystal layer disposed between the pair of translucent substrates and having a dichroic dye added thereto; A driving circuit for applying a voltage to the electrode and one or more polarizing plates provided on the light incident side to the viewing angle control device, and the electrode is applied with a voltage by the driving circuit. The liquid crystal layer is arranged so as to locally generate an electric field substantially parallel to the substrate surface of the translucent substrate in a partial region of the liquid crystal layer, and the drive circuit is a liquid crystal of the liquid crystal layer of the viewing angle control device By changing the arrangement state of the molecules, the display state is changed to the first Switchable between a first state that provides a viewing angle range and a second state that is within the first viewing angle range and provides a second viewing angle range that is narrower than the first viewing angle range It is characterized by doing.

In the above configuration, one or more polarizing plates are arranged on the light incident side of the viewing angle control device. Note that the viewing angle control device and the polarizing plate are not necessarily adjacent to each other, and some component may be interposed between them. In the above configuration, a predetermined voltage is applied to the electrodes of the viewing angle control device, and an electric field substantially parallel to the substrate surface of the translucent substrate is locally generated. Accordingly, by locally changing the direction of the liquid crystal director of the liquid crystal layer containing the dichroic dye, the polarized light incident on the viewing angle control device can be transmitted or shielded according to the viewing angle. That is, by switching between the application of voltage to the electrode and the non-application of the voltage, the display state is changed from the first state (wide viewing angle) that provides the first viewing angle range to the first viewing angle range. It is possible to switch to either the second state (narrow viewing angle) that provides a second viewing angle range that is narrower than the first viewing angle range. Note that “wide viewing angle” and “narrow viewing angle” mean a relatively wide viewing angle and a relatively narrow viewing angle that do not mean a specific absolute angle range. In the above configuration, by applying a voltage to the electrodes of the viewing angle control device, it is possible to realize a narrow viewing angle state in which the display can be visually recognized only in a limited viewing angle. As a result, the viewing angle can be controlled by switching between light transmission and shielding rather than reducing the display contrast on the wide viewing angle side as in the conventional viewing angle control technique. As a result, it can be adapted to various usage environments and applications. Display can be provided.

[0011] In the display according to the present invention, the liquid crystal layer of the viewing angle control device includes a positive nematic liquid crystal, and the polarization transmission axis of the polarizing plate is disposed substantially perpendicular to the rubbing direction of the alignment film. The driving circuit provides the first viewing angle range by applying no voltage to the liquid crystal layer, and provides the second viewing angle range by applying a predetermined voltage to the liquid crystal layer. It is preferable. A narrow viewing angle range is provided by applying a predetermined voltage in special cases where privacy protection is required, etc., without applying a voltage in the case of a general display state that realizes a wider viewing angle. This is because power consumption can be reduced.

[0012] In the display according to the present invention, the alignment films provided on each of the pair of translucent substrates of the viewing angle control device are rubbed in parallel and in the same direction, or in parallel and in opposite directions. /! I like to do it! /

[0013] The display according to the present invention may be configured such that the display device emits linearly polarized light, and the polarizing plate is provided on the viewing angle control device side in the display device. .

[0014] In the display according to the present invention, the display device may be a transmissive liquid crystal display device, and may further include a backlight. In this configuration, the viewing angle control device force S may be arranged between the backlight and the transmissive liquid crystal display device, and the viewing angle control device may be arranged in front of the transmissive liquid crystal display device. It is good also as an aspect arrange | positioned. Furthermore, the backlight is preferably a directional backlight having directivity in the normal direction.

[0015] The display according to the present invention may be configured such that the display device is a reflective liquid crystal display device or a transflective liquid crystal display device. Alternatively, in the display according to the present invention, the display device is a self-luminous display device, the viewing angle control device is disposed in front of the self-luminous display device, and the polarizing plate is the self-luminous display device. A configuration provided between the light emitting display device and the viewing angle control device may be adopted.

[0016] In order to achieve the above object, the first viewing angle control device according to the present invention is disposed in front of a display device that is driven according to an image to be displayed and emits linearly polarized light. A viewing angle control device used for controlling a viewing angle of a display device, comprising a pair of translucent substrates, electrodes provided on at least one of the pair of translucent substrates, and the pair of translucent substrates An alignment film provided on each of the luminescent substrates, a liquid crystal layer disposed between the pair of translucent substrates, to which a dichroic dye is added, and a drive circuit for applying a voltage to the electrodes, The electrode is disposed so as to locally generate an electric field substantially parallel to the substrate surface of the translucent substrate in a region of the liquid crystal layer when a voltage is applied by the drive circuit. The driving circuit changes the alignment state of the liquid crystal molecules in the liquid crystal layer of the viewing angle control device, thereby changing the display state to the first state providing the first viewing angle range and the first viewing angle. Provides a second viewing angle range that is within the range and narrower than the first viewing angle range It is possible to switch between the second state and the second state.

[0017] In order to achieve the above object, the second viewing angle control device, which is effective in the present invention, is arranged on the back surface of a display device that is driven in accordance with an image to be displayed and emits linearly polarized light. A viewing angle control device used for controlling a viewing angle of a display device, comprising a pair of translucent substrates, electrodes provided on at least one of the pair of translucent substrates, and the pair of translucent substrates An alignment film provided on each of the transmissive substrates, a liquid crystal layer disposed between the pair of translucent substrates and added with a dichroic dye, a driving circuit for applying a voltage to the electrodes, and the visual field It comprises at least one polarizing plate provided on the light incident side to the angle control device, and the electrode is applied with a voltage in a part of the liquid crystal layer when a voltage is applied by the drive circuit. It is arranged so as to locally generate an electric field substantially parallel to the substrate surface of the translucent substrate. The driving circuit changes the alignment state of the liquid crystal molecules in the liquid crystal layer of the viewing angle control device, thereby changing the display state to a first state that provides a first viewing angle range, and a first viewing field. It is possible to switch between a second state that provides a second viewing angle range that is within the angular range and is narrower than the first viewing angle range.

[0018] In order to achieve the above object, the third viewing angle control device, which is effective in the present invention, is disposed in front of a self-luminous display device driven according to an image to be displayed. A viewing angle control device used for controlling a viewing angle of a light-emitting display device, comprising: a pair of translucent substrates; an electrode provided on at least one of the pair of translucent substrates; An alignment film provided on each of the translucent substrates and the pair of translucent substrates A liquid crystal layer arranged and added with a dichroic dye, a drive circuit for applying a voltage to the electrode, and one or more polarizing plates provided on the light incident side to the viewing angle control device, The electrodes are arranged so as to locally generate an electric field substantially parallel to the substrate surface of the translucent substrate in a partial region of the liquid crystal layer when a voltage is applied by the drive circuit. The driving circuit changes the alignment state of the liquid crystal molecules in the liquid crystal layer of the viewing angle control device, thereby changing the display state to a first state that provides a first viewing angle range, and a first viewing field. It is possible to switch between a second state that provides a second viewing angle range that is within the angular range and is narrower than the first viewing angle range.

The invention's effect

[0019] As described above, according to the present invention, a display that can be adapted to various usage environments and applications by switching the display state between a wide viewing angle and a narrow viewing angle, and the viewing angle control used therefor. Device.

Brief Description of Drawings

[0020] FIG. 1 is a cross-sectional view showing a schematic configuration of a display according to an embodiment of the present invention.

[FIG. 2] In FIG. 2, (a) is a schematic diagram showing the behavior of liquid crystal molecules and dichroic dye molecules when no voltage is applied to the electrodes, and (b) is the liquid crystal molecules when voltage is applied to the electrodes and It is a schematic diagram showing a dichroic dye molecule screen.

FIG. 3 is a schematic plan view showing a configuration of electrodes provided in the viewing angle control device.

4 is a cross-sectional view showing the gap between the electrodes of the viewing angle control device in FIG. 4, and (b) is a schematic cross-sectional view showing the state of the electric field generated by the voltage applied to the electrodes of the viewing angle control device. Ah

FIG. 5 is a chart showing a luminance distribution at a wide viewing angle of a display according to an embodiment of the present invention.

FIG. 6 is a chart in which the luminance distribution at the narrow viewing angle of the display according to one embodiment of the present invention is omitted.

FIG. 7 is a luminance distribution diagram of a general backlight (without a lens sheet).

FIG. 8 is a luminance distribution diagram of an example of a directional backlight in which lens sheets are stacked. [Fig. 9] Fig. 9 is a luminance distribution diagram of another example of a directional backlight with a laminated lens sheet. [Fig. 10] Fig. 10 shows another example of a directional backlight with a laminated lens sheet. It is a luminance distribution diagram.

[Fig. 11] Fig. 11 is a luminance polar angle characteristic diagram showing the luminance distribution in the horizontal direction of the backlight (azimuth angle Θ = 0 ° force and Θ = 180 ° direction), with or without a lens sheet.

[FIG. 12] FIG. 12 is a luminance polar angle characteristic diagram showing the luminance distribution in the vertical direction of the backlight (azimuth angle Θ = 90 ° force is also Θ = 270 ° direction) with or without the lens sheet.

[Fig. 13] Fig. 13 shows the viewing angle control in the narrow viewing angle state when only the knocklight is changed to the directional backlight having the brightness distribution shown in Fig. 10 under the same conditions as in Fig. 6. It is a chart which shows the luminance distribution of the liquid crystal panel.

FIG. 14 is a cross-sectional view showing a configuration of another modification of the display which is effective in the embodiment of the present invention.

FIG. 15 is a cross-sectional view showing a configuration of still another modified example of the display which is effective in the embodiment of the present invention.

FIG. 16 is a cross-sectional view showing a configuration of still another modified example of the display which is effective for the embodiment of the present invention.

[FIG. 17] FIG. 17 is a cross-sectional view showing a configuration of still another modification of the display which is effective in the embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in the drawings referred to below, for convenience of explanation, among the constituent members of the embodiment of the present invention, only the main members necessary for explaining the present invention are shown in a simplified manner. Therefore, the display according to the present invention can include arbitrary components not shown in the drawings referred to in this specification. In addition, the dimensions of the members in each figure do not faithfully represent the actual dimensions of the constituent members and the dimensional ratio of each member.

FIG. 1 is a cross-sectional view showing a schematic configuration of a liquid crystal display 100 according to an embodiment of the present invention. As shown in FIG. 1, the liquid crystal display 100 is a display liquid that displays images. It has two liquid crystal panels, a crystal panel 1 (display device) and a viewing angle control liquid crystal panel 2 (viewing angle control device). The display liquid crystal panel 1 in this embodiment is a transmissive type, and a backlight 3 is used as a light source. In the liquid crystal display 100 shown in FIG. 1, the display liquid crystal panel 1 is disposed between the backlight 3 and the viewing angle control liquid crystal panel 2. As will be described later, the liquid crystal display 100 performs a switching operation of the liquid crystal in the viewing angle control liquid crystal panel 2 so that an image on the display liquid crystal panel 1 can be viewed in a wide viewing angle (wide viewing angle). The display state can be switched between a narrow viewing angle (narrow viewing angle). The narrow viewing angle is particularly suitable when others do not want to see the image on the LCD panel 1 for display, and the wide viewing angle is used for other normal use or the image on the LCD panel 1 for display. It is preferably used when a plurality of people want to watch at the same time.

The display liquid crystal panel 1 includes a liquid crystal cell 11 in which a liquid crystal is sandwiched between a pair of translucent substrates, and polarizing plates 12 and 13 provided on the front and back of the liquid crystal cell 11. The liquid crystal mode and cell structure of the liquid crystal cell 11 are arbitrary. Further, the drive mode of the display liquid crystal panel 1 is also arbitrary. In other words, as the liquid crystal panel 1 for display, any liquid crystal panel that can display characters, images, or moving images can be used. Accordingly, the detailed structure of the display liquid crystal panel 1 is not shown in FIG. 1, and the description thereof is also omitted. Further, the display liquid crystal panel 1 may be a panel capable of color display or a panel dedicated to monochrome display. Furthermore, since any known backlight with no limitation on the configuration of the knocklight 3 can be used, illustration and description of the detailed structure of the backlight 3 are also omitted.

[0024] As shown in Figs. 2 (a) and (b), the viewing angle control liquid crystal panel 2 includes a pair of translucent substrates 21a and 21b and translucent substrates 21a and 21b. Alignment films 22a and 22b formed on the surface, a liquid crystal layer 23, and a drive circuit (not shown in FIG. 2) for applying a drive voltage to the liquid crystal layer 23 are provided. In the examples of FIGS. 2 (a) and (b), in the viewing angle control liquid crystal panel 2, a transparent electrode 24a is formed only on the translucent substrate 21a side using, for example, ITO (Indium Tin Oxide). ing. The liquid crystal layer 23 includes a nematic liquid crystal that has positive dielectric anisotropy (so-called positive type) and is not dyed, and a positive type dichroic dye. In Figs. 2 (a) and (b), 23m represents a liquid crystal molecule and 23d represents a dichroic dye molecule.

[0025] Here, the arrangement of the transparent electrode 24a on the translucent substrate 21a and the connection to the drive circuit The relationship will be described in detail with reference to FIG. As shown in FIG. 3, the transparent electrodes 24a are arranged on the translucent substrate 21a in parallel with each other and in pairs of two. Of the two transparent electrodes 24a belonging to one pair, one is connected to the positive side of the drive circuit 25 of the viewing angle control liquid crystal panel 2, and the other is connected to the negative side of the drive circuit 25. . In Fig. 3, the transparent electrode connected to the positive side of the drive circuit 25 is denoted as 24a.

The transparent electrode connected to the negative electrode side is denoted as 24a. Note that i is a natural number from! That is, in the example of FIG. 3, 2n transparent electrodes 24a are provided on the translucent substrate 21a.

[0026] The gap between the two transparent electrodes 24a, 24a belonging to the same pair is smaller than the gap between the two transparent electrodes belonging to different pairs. For example, it is preferable that the gap between the two transparent electrodes 24a belonging to different pairs is about 1.5 times or more the gap between the transparent electrodes 24a belonging to the same pair. For example, the cell gap of the viewing angle control liquid crystal panel 2 is 9. Οπι, the width W of the transparent electrode 24a shown in FIG. 4 (a) is 3 · O ^ m, and two transparent electrodes 24a belonging to the same pair When the gap W is 3. O ^ m, the gap W between the two transparent electrodes 24a belonging to different pairs

(For example, the gap between the transparent electrode 24a and the transparent electrode 24a) is preferably 4.5 m or more. Since the transparent electrodes 24a are arranged in this way, when the switch 25s of the drive circuit 25 is closed, as shown in FIG. 4 (b), between these transparent electrodes 24a and 24a belonging to the same pair, An electric field E that is perpendicular to the longitudinal direction and substantially horizontal is generated on the substrate surface of the translucent substrate 21a.

[0027] Here, using Fig. 2 (a) and (b), the liquid crystal molecules 23m and the dichroic dye molecules 23d when the voltage application to the transparent electrode 24a is turned ON / OFF by the drive circuit 25. Explain the behavior. 2A and 2B are schematic views showing the alignment state of the liquid crystal layer 23. FIG. In these drawings, in order to make the behavior of the liquid crystal molecules 23m and the dichroic dye molecules 23d easier, the sizes and the like of these molecules are exaggerated. 2A shows a state where no voltage is applied from the drive circuit 25, and FIG. 2B shows a state where a predetermined voltage is applied from the drive circuit 25. FIG.

[0028] In FIGS. 2 (a) and (b), the rubbing direction of the self-directing films 22a and 22b is a direction perpendicular to the paper surface of FIG. 2 and the same direction (so-called parallel rubbing), or Reverse (yes This is anti-parallel rubbing). Further, the polarizing plate 12 is arranged so that the polarization transmission axis thereof is substantially perpendicular (80 ° to 100 °) with the rubbing direction of the alignment films 22a and 22b.

In such a configuration, as shown in FIG. 2 (a), when no voltage is applied from the driving circuit 25, the liquid crystal molecules 23m and the dichroic dye molecules 23d are rubbed in the molecular long axis. Are aligned in a direction parallel to the. In this case, the linearly polarized light L1 to L3 emitted from the backlight 3 and transmitted through the polarizing plate 12 of the display liquid crystal panel 1 and incident on the viewing angle control liquid crystal panel 2 is transmitted to the viewing angle control liquid crystal panel 2. Regardless of the incident angle, the direction of vibration is perpendicular to the molecular long axis of the liquid crystal molecule 23m, so that the force of the liquid crystal layer 23 is transmitted without being affected. Therefore, the observer VI in the direction of transmitting the linearly polarized light L1, the observer V2 in the direction of transmitting the linearly polarized light L2, and the observer V3 in the direction of transmitting the linearly polarized light L3! However, you can see the display on the LCD panel 1 for display. In other words, when a voltage is applied from the drive circuit 25 to the liquid crystal layer 23 of the viewing angle control liquid crystal panel 2, a wide viewing angle is obtained.

On the other hand, when a voltage is applied from the drive circuit 25, as shown in FIG. 4 (b), a part of the liquid crystal layer 23, that is, two transparent electrodes 24a forming a pair , 24a

i + i-

In the region where E occurs, the liquid crystal molecules 23m and the dichroic dye molecules 23d are arranged so that the molecular major axes are aligned in the direction of the generated electric field. However, in the region where the electric field E does not occur, the liquid crystal molecules 23m and the dichroic dye molecules 23d are aligned with the molecular long axes in the direction parallel to the rubbing direction. Therefore, when a voltage is applied from the drive circuit 25, the alignment state of the liquid crystal layer 23 of the viewing angle control liquid crystal panel 2 is not uniform! /. As shown in Fig. 2 (b) and Fig. 4 (b), the vibration of linearly polarized light L2 that has passed through the polarizing plate 12 of the display liquid crystal panel 1 and entered the viewing angle control liquid crystal panel 2 almost perpendicularly. In the region where the electric field E is generated by the two transparent electrodes 24a and 24a that form a pair, the liquid crystal molecules 2 i + i-

It is perpendicular to the molecular long axis of 3m and the dichroic dye molecule 23d. Accordingly, the linearly polarized light L2 is transmitted without being affected by the liquid crystal layer 23. However, the linearly polarized light LI, L3 incident on the viewing angle control liquid crystal panel 2 from an oblique direction has liquid crystal molecules in a region where the electric field E is generated by the pair of transparent electrodes 24a, 24a. 23m and

i + i- Dichroic dye molecule It corresponds to the molecular long axis direction of 23d. Therefore, linearly polarized light LI, L3 is It is absorbed by the chromatic dye molecules 23d and shielded by the liquid crystal layer 23. Therefore, the observer V2 can visually recognize the display on the display liquid crystal panel 1. The observers VI and V3 cannot visually recognize the display on the display liquid crystal panel 1. That is, when a voltage is applied from the drive circuit 25 to the liquid crystal layer 23 of the viewing angle control liquid crystal panel 2, a narrow viewing angle can be obtained.

As described above, as can be seen from FIGS. 2 and 4, in the liquid crystal display 100 which is effective in the present embodiment, the display state is changed by switching the applied voltage of the viewing angle control liquid crystal panel 2 on and off. It is possible to switch between a wide viewing angle and a narrow viewing angle. FIG. 5 is a chart showing the luminance distribution in a wide viewing angle state obtained when no voltage is applied to the viewing angle control liquid crystal panel 2. FIG. 6 is a chart showing a luminance distribution in a narrow viewing angle state obtained when a voltage is applied to the viewing angle control liquid crystal panel 2. In FIG. 6, the azimuth angle is 90. Force, linear force connecting 270 °, and corresponds to the normal direction to the page of Fig. 4. As can be seen from FIG. 5 and FIG. 6, by using the liquid crystal panel 2 for controlling the viewing angle, which is effective in this embodiment, a wide viewing angle is ensured with respect to the screen of the liquid crystal display 100 at the wide viewing angle. At a narrow viewing angle, it is possible to prevent prejudice from obliquely behind in the left and right directions of the LCD 100 screen.

Note that the liquid crystal display 100 which is effective in the present embodiment may use a general knock light (a backlight having a substantially average luminance distribution over the entire polar angle range) as the backlight 3. It is preferable to use a directional backlight. A directional backlight is a backlight having a luminance distribution in which the luminance in the relatively narrow angle range centered on the front of the display, that is, the polar angle φ = 0 °, is higher than the luminance of other parts. Yes, it can be realized by laminating one or more lens sheets on a general backlight.

Here, with reference to FIG. 7 to FIG. 10, the characteristics of the backlight applicable to the liquid crystal display 100 which is applicable to the present embodiment will be described. Fig. 7 shows the luminance distribution of backlight 3 when a general backlight (without a lens sheet) is used as a directional backlight. In this case, backlight 3 has a symmetrical luminance distribution in the horizontal direction (azimuth angle θ = 0 ° force is also in the direction of θ = 180 °), but the vertical direction (azimuth angle from θ = 90 ° to Θ = 270 ° The direction of the brightness peak P around the azimuth angle Θ = 270 ° and polar angle φ = 45 °

1

Have. The design is such that the brightness peak P of knocklight 3 is shifted from the front direction in this way.

1

This is because, as will be described later, when two lens sheets are laminated, the luminance peak is positioned directly in front (polar angle φ = 0 °). That is, when no lens sheet is used or when only one lens sheet is laminated, the luminance peak of the backlight 3 is different from the position shown in FIG.

FIGS. 8 to 10 show the luminance distribution of the knocklight 3 in the case of a directional backlight using a lens sheet. FIG. 8 is a luminance distribution diagram of the backlight 3 when a lens sheet is laminated on the light emitting surface of the backlight having the luminance characteristics shown in FIG. As a lens sheet, “BEF II 90/50 (trade name)” manufactured by Sumitomo 3EM Co., Ltd. was used, but is not limited thereto. In this case, as shown in Fig. 8, the luminance distribution is changed by laminating one lens sheet on the light exit surface, and the luminance peak P appears in the vicinity of azimuth angle Θ = 270 ° and polar angle φ = 30 °. . In the horizontal direction, the polar angle is approximately 0 ° ≤ ≤40. In the vertical range, the brightness is relatively higher than the other parts when the polar angle is in the range of 0 ° ≤ φ≤60 °.

[0035] FIG. 9 shows a backlight in the case where the same lens sheet as described above is laminated on the light exit surface of the backlight having the luminance characteristics shown in FIG. FIG. 4 is a luminance distribution diagram of light 3. In this case, as shown in Fig. 9, the luminance peak P has an azimuth angle Θ = 270

Three

The polar angle is in the range of about 0 ° ≤ φ≤60 ° in the horizontal direction and the polar angle is in the range of about 0 ° ≤ φ≤40 ° in the vertical direction. Therefore, the luminance is relatively higher than other portions.

[0036] FIG. 10 shows a backlight 3 in a case where two same lens sheets as described above are laminated on the light emitting surface of the backlight having the luminance characteristics shown in FIG. FIG. In this case, as shown in FIG.

Four

Θ = 270 °, polar angle around φ = 5 °), the polar angle in the horizontal direction is approximately 0 ° ≤ φ≤40 °, and the polar angle in the vertical direction is approximately 0 ° ≤ φ≤40 In the range of °, the brightness is relatively higher than other parts.

[0037] Figure 11 shows the horizontal direction of the backlight 3 (azimuth angle Θ = 0 ° force, Θ = 180 ° direction). FIG. 6 is a luminance polar angle characteristic diagram showing the luminance distribution according to the presence or absence of a lens sheet. FIG. 12 is a luminance-polar angle characteristic diagram showing the luminance distribution in the vertical direction of the backlight 3 (azimuth angle Θ = 90 ° force and Θ = 270 ° direction) according to the presence or absence of the lens sheet. In Fig. 11, the polar angle on the azimuth angle Θ = 180 ° side from the front direction (polar angle φ = 0 °) is shown with a negative sign. In Fig. 12, the front direction (polar angle φ = 0) is shown. The polar angle on the side of azimuth angle Θ = 270 ° from °) is shown with a negative sign.

[0038] As shown in FIGS. 11 and 12, when one lens sheet is laminated, the normal direction (polar angle)

The brightness of Φ = 0 ° is about 1.8 times that without the lens sheet (the rate of increase in brightness is about 1.60). When two lens sheets are stacked, the luminance in the normal direction is about 2.8 times that without the lens sheet (the rate of increase in luminance is about 1.95). However, the brightness increase rate differs depending on the composition and design of the backlight system as a whole or the overall lighting effect, so the above brightness increase rate is not always optimal! /.

Further, Th shown in FIGS. 11 and 12 represents a luminance corresponding to 50% of the luminance in the normal direction when one lens sheet is laminated. The polar angle range (horizontal direction) at which brightness greater than Th can be obtained is approximately 66 ° for the lens sheet arrangement shown in FIG. 8, and about 96 ° for the lens sheet arrangement shown in FIG. . Similarly, the polar angle range (vertical direction) at which brightness greater than this Th is obtained is approximately 99 ° for the lens sheet arrangement shown in FIG. 8, and about 66 ° for the lens sheet arrangement shown in FIG. It is. When two lens sheets are stacked, the polar angle range that provides a luminance equivalent to 50% of the luminance in the normal direction is about 58 ° in the horizontal direction and about 88 ° in the vertical direction.

[0040] Fig. 6 shows the luminance distribution when a general backlight having an almost average luminance distribution over the entire polar angle range, which is not a directional backlight, is used as the backlight 3. However, when only the backlight 3 is changed to the directional backlight having the luminance distribution shown in FIG. 10 under the same conditions as those in FIG. 6, the luminance distribution as shown in FIG. Is obtained. That is, as the luminance peak approaches the front direction, the range of azimuth angles in which the light is shielded becomes wider. Therefore, it is possible to realize a display device that can more reliably prevent a person from being looked at by someone else who is diagonally behind.

FIG. 14 shows a liquid crystal display as a modification of the liquid crystal display 100 according to the present embodiment. The structure of Ray 200 is shown. As can be seen from a comparison between Fig. 1 and Fig. 14, the liquid crystal display 100 and the liquid crystal display 200 have the stacking order of the display liquid crystal panel 1 and the viewing angle control liquid crystal panel 2 reversed. . That is, as shown in FIG. 14, the liquid crystal display 200 has a configuration in which the viewing angle control liquid crystal panel 2 is disposed between the backlight 3 and the display liquid crystal panel 1. In the liquid crystal display 200, the display liquid crystal panel 1 may be a transflective liquid crystal panel.

The liquid crystal display 200 includes a linearly polarizing plate 26 between the backlight 3 and the viewing angle control liquid crystal panel 2. That is, in the case of the liquid crystal display 100 shown in FIG. 1, the polarizing plate 12 of the display liquid crystal panel 1 is a force that functions as a polarizing plate provided on the light incident side to the viewing angle control liquid crystal panel 2. This is because in the case of the liquid crystal display 200 shown, it is necessary to provide a linear polarizing plate on the nocrite 3 side. Note that the polarization transmission axis of the linear polarizing plate 26 is arranged perpendicular to the rubbing direction of the viewing angle control liquid crystal panel 2, similarly to the polarization transmission axis of the polarizing plate 12 in the liquid crystal display 100.

Note that this embodiment merely shows specific examples of the present invention, and there is no intention to limit the technical scope of the present invention to these specific examples. For example, FIG. 2 shows an example in which the transparent electrode 24a is formed only on the light incident side translucent substrate 21a side in the viewing angle control liquid crystal panel 2. However, as shown in FIG. 15, the same transparent electrode 24b may be formed so that the other transparent substrate 21b faces the transparent electrode 24a of the transparent substrate 21a. According to this configuration, an electric field can be formed from both of the translucent substrates 21a and 21b to the liquid crystal layer 23, so that there is an advantage that the alignment state can be uniformly controlled over the thickness direction of the liquid crystal layer 23. Alternatively, the transparent electrode 21b on the light incident side may not be provided with a transparent electrode, and the transparent electrode 24b shown in FIG. 15 may be provided only on the transparent substrate 21b.

In addition, the transparent electrodes 24a and 24b of the viewing angle control liquid crystal panel 2 have two transparent electrodes belonging to different pairs over the entire substrate surface of the translucent substrate, as shown in FIGS. The gap W between the poles (see Fig. 4 (a)) may be equal, or the center of the translucent substrate

dp

In such a case, the gap W should be made smaller toward the end of the translucent substrate.

dp dp

May be. Alternatively, the display liquid crystal panel 1 has a display screen divided into a plurality of areas. In such a case, a region where information with high confidentiality is displayed may be determined in advance, and the transparent electrodes 24a and 24b may be provided only in portions corresponding to the region in the viewing angle control liquid crystal panel 2.

[0045] In the above description, the force display device using the transmissive liquid crystal panel as a specific example of the display device is not limited to this. For example, a reflective or transflective liquid crystal display panel can be used as the display device. In addition to non-light emitting display devices such as liquid crystal display panels, for example, CRT (Cathode Ray Tube), plasma display, organic EL (Electro Luminescence) element, inorganic EL element, LED (Light Emitting Diode) display. A self-luminous display device such as a ray, a vacuum fluorescent display, a field emission display, or a surface-conduction electron display can also be used.

FIG. 16 shows a configuration example in the case where a reflective liquid crystal display panel is used as the display device. The liquid crystal display 300 shown in FIG. 16 has a configuration in which the viewing angle control liquid crystal panel 2 is disposed on the front surface (observer side) of the reflective liquid crystal display panel 30. The reflective liquid crystal display panel 30 includes a reflective liquid crystal cell 31 having a reflector (not shown) on the substrate opposite to the observer, and a linear polarizing plate 32 disposed on the upper surface of the reflective liquid crystal cell 31. It has. Note that the polarization transmission axis of the linear polarizing plate 32 is arranged substantially perpendicular to the rubbing direction of the viewing angle control liquid crystal panel 2, similarly to the polarization transmission axis of the polarizing plate 12 in the liquid crystal display 100. Since the structure and operation of the reflective liquid crystal cell are well known, detailed description thereof is omitted here. In the liquid crystal display 300 shown in FIG. 16, similarly to the liquid crystal display 100, the display state of the liquid crystal display 300 is changed to a wide viewing angle by switching the voltage applied to the viewing angle control liquid crystal panel 2 between ON and OFF. Can be switched between narrow viewing angles

[0047] FIG. 17 shows a configuration example when a self-luminous display device such as an EL element is used as the display device. The display 400 shown in FIG. 17 has a configuration in which the viewing angle control liquid crystal panel 2 is disposed on the front surface (observer side) of the self-luminous display device 40. In this case, the linearly polarizing plate 26 is disposed between the spontaneous light display device 40 and the viewing angle control liquid crystal panel 2. The polarization transmission axis of the linear polarizing plate 26 is the polarization of the polarizing plate 12 in the liquid crystal display 100. Like the light transmission axis, the viewing angle control liquid crystal panel 2 is arranged substantially perpendicular to the rubbing direction. In the display 400 shown in FIG. 16, as with the liquid crystal display 100, the voltage applied to the viewing angle control liquid crystal panel 2 is switched between ON and OFF to change the display state of the display 400 to a wide viewing angle and a narrow viewing angle. You can switch between the corners.

[0048] Note that even in the case of! / In the above-described embodiment, even when the display is in a narrow viewing angle, a message, an image, an icon, or the like for informing the user that the display state is a narrow viewing angle. May be displayed on the screen of the display device.

[0049] In any of the above embodiments, the driving circuit of the viewing angle control device operates according to the content of the image displayed on the display device, and automatically switches between the narrow viewing angle and the wide viewing angle. You may make it change. For example, when the display is used to view web pages on the Internet, the software flag associated with each page is referred to according to the content of the web page, and it is preferable that the content is not seen by others. The display state may be automatically switched to a narrow viewing angle. Further, when the browser is activated in the encryption mode, the display state may be switched to a narrow viewing angle.

[0050] In addition, when it is a part of the display force data input device, or when it is related to the data input device, the data type being input or the data type to be input is confidential. It is also possible to adjust the display state to switch to a narrow viewing angle. For example, if the display is automatically switched to a narrow viewing angle when the user enters some personal identification number, etc.

[0051] In any of the above embodiments, the viewing angle control device may be formed as a module or a cover that can be detached from the display device. When such a removable module is attached to the display device, it can be electrically connected to the display device to obtain appropriate power and control signals.

[0052] In any of the above-described embodiments, an optical sensor (ambient sensor) that measures the ambient light of the display is further provided, and when the measured value of the optical sensor falls below a predetermined threshold, the display on the display It is also preferable to make the state a narrow viewing angle.

[0053] It should be noted that the present invention has a wide variety of uses, such as a display and a viewing angle control device.

For example, notebook personal computers, portable information terminals (PDAs), portable games Applicable to various devices such as ATMs (automatic cash dispensers), information terminals installed in public places, ticket vending machines, and in-vehicle displays. Is done.

[0054] Further, the viewing angle control device according to the present invention has a force S that may be implemented in a state of being incorporated in a display S, and is manufactured and distributed as a display component by itself. There is a possibility.

Industrial applicability

[0055] The present invention is industrially applicable as a display that can be adapted to various usage environments and applications by switching between a wide viewing angle and a narrow viewing angle, and a viewing angle control device used therefor.

Claims

The scope of the claims

[1] a display device driven according to an image to be displayed;

A display that is disposed on at least one of a rear surface and a front surface of the display device and includes a viewing angle control device that controls a viewing angle of the display device,

The viewing angle control device includes:

A pair of translucent substrates;

An electrode provided on at least one of the pair of translucent substrates;

An alignment film provided on each of the pair of translucent substrates;

A liquid crystal layer disposed between the pair of translucent substrates, to which a dichroic dye is added; a drive circuit for applying a voltage to the electrodes;

One or more polarizing plates provided on the light incident side to the viewing angle control device, and when the electrode is applied with a voltage by the drive circuit, the electrode in the partial region of the liquid crystal layer It is arranged so as to locally generate an electric field substantially parallel to the substrate surface of the translucent substrate,

The drive circuit changes the alignment state of the liquid crystal molecules in the liquid crystal layer of the viewing angle control device, thereby changing the display state to a first state that provides a first viewing angle range, and a first viewing angle. A display that is switchable between a second state that is within the range and provides a second viewing angle range that is narrower than the first viewing angle range.

[2] The liquid crystal layer of the viewing angle control device includes a positive nematic liquid crystal,

The polarizing transmission axis of the polarizing plate is disposed substantially perpendicular to the rubbing direction of the alignment film, and the driving circuit provides the first viewing angle range by applying no voltage to the liquid crystal layer, and the liquid crystal The display of claim 1, wherein the second viewing angle range is provided by applying a predetermined voltage to the layer.

[3] Claims, wherein the alignment films provided on each of the pair of translucent substrates of the viewing angle control device are rubbed in parallel and in the same direction or in parallel and in opposite directions. The display according to 1 or 2.

[4] The display device is a display device that emits linearly polarized light,

The polarizing plate is provided on the display device side and on the viewing angle control device side. The display according to any one of claims 1 to 3.

5. The display device according to claim 1, wherein the display device is a transmissive liquid crystal display device and further includes a backlight.

~ 4! /, The display according to one item.

6. The display according to claim 5, wherein the viewing angle control device is disposed between the backlight and the transmissive liquid crystal display device.

7. The viewing angle control device is disposed on a front surface of the transmissive liquid crystal display device.

5. The display according to 5.

8. The backlight is a directional backlight having directivity in the normal direction.

The display as described in any one of -7.

[9] The display according to any one of claims 1 to 4, wherein the display device is a reflective liquid crystal display device or a transflective liquid crystal display device.

[10] The display device is a self-luminous display device,

The viewing angle control device is disposed in front of the self-luminous display device,

4. The display according to claim 1, wherein the polarizing plate is provided between the self-luminous display device and the viewing angle control device.

[11] A viewing angle control device that is arranged in front of a display device that is driven according to an image to be displayed and emits linearly polarized light, and is used to control the viewing angle of the display device. An optical substrate;

An electrode provided on at least one of the pair of translucent substrates;

An alignment film provided on each of the pair of translucent substrates;

A liquid crystal layer disposed between the pair of translucent substrates, to which a dichroic dye is added, and a drive circuit for applying a voltage to the electrodes;

The electrode is arranged to locally generate an electric field substantially parallel to the substrate surface of the translucent substrate in a partial region of the liquid crystal layer when a voltage is applied by the drive circuit.

The drive circuit changes the alignment state of the liquid crystal molecules in the liquid crystal layer of the viewing angle control device, thereby changing the display state to a first state that provides a first viewing angle range, and a first viewing angle. A second shape that provides a second viewing angle range that is within the range and is narrower than the first viewing angle range The viewing angle control device is characterized in that it can be switched between states.

[12] A viewing angle control device that is arranged in accordance with an image to be displayed and is arranged on the back surface of a display device that emits linearly polarized light and is used to control the viewing angle of the display device. An optical substrate;

An electrode provided on at least one of the pair of translucent substrates;

An alignment film provided on each of the pair of translucent substrates;

One or more polarizing plates provided on the light incident side to the viewing angle control device are provided, and when the electrode is applied with a voltage by the driving circuit, the electrode transmits the transparent electrode in a partial region of the liquid crystal layer. It is placed so as to locally generate an electric field substantially parallel to the substrate surface of the optical substrate,

The drive circuit changes the alignment state of the liquid crystal molecules in the liquid crystal layer of the viewing angle control device, thereby changing the display state to a first state that provides a first viewing angle range, and a first viewing angle. A viewing angle control device capable of switching between a second state that provides a second viewing angle range that is within the range and is narrower than the first viewing angle range.

[13] A viewing angle control device that is disposed in front of a self-luminous display device that is driven according to an image to be displayed and is used to control the viewing angle of the self-luminous display device, A translucent substrate;

An electrode provided on at least one of the pair of translucent substrates;

An alignment film provided on each of the pair of translucent substrates;

The drive circuit changes the alignment state of the liquid crystal molecules in the liquid crystal layer of the viewing angle control device. Providing a first viewing angle range that provides a first viewing angle range and a second viewing angle range that is within the first viewing angle range and is narrower than the first viewing angle range. A viewing angle control device capable of switching between a second state and a second state.