JP2006195388A - View-angle control display device and view-angle control element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a view-angle control element and a view-angle control display device that greatly cut off light in a view-angle control direction in a view-angel control state. <P>SOLUTION: The view-angle control display device 100 as an embodiment of the present invention is equipped with a liquid crystal display element 101, the view-angle control element 102, and a back light unit 103. The view-angle control display device 100 is so configured that a display surface of the liquid crystal display element 101 can be viewed from a passenger's seat side, but can not be viewed from a driver's seat side in the view-angle control state. Especially, the view-angle control element 102 is equipped with two layers of a 1st TN element 1021 and a 2nd TN element 1022 so that the display surface can surely not be viewed from the driver's seat side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a viewing angle control display device and a viewing angle control element.

  Currently, display devices are widely used as an interface between humans and machines, and have made remarkable progress. In many cases, it is preferable that the viewing angle of the display device is wide. Therefore, the development of display devices has been advanced in the direction of widening the viewing angle.

  Information with high security may be displayed on such a display device. At this time, if information with high security is displayed on a display device with a wide viewing angle, there is a possibility that the display can be seen by a third party. Therefore, the need to control the viewing angle within a specific range is increasing due to the demand for privacy protection.

  Recently, with the development of car navigation technology, many cars have been equipped with car navigation systems. Usually, a display device for displaying a map in a car navigation system simultaneously functions as a television receiver. At this time, the display device can be visually recognized from the driver's seat as a matter of course, but there is a safety problem for the driver to watch the television image while driving. Therefore, when the display device displays a TV image, it is necessary to control the viewing angle so that the screen can be seen from the passenger seat but not the driver seat. Is growing.

Various means have been developed as a viewing angle control technique for display devices (see, for example, Patent Documents 1 to 3 and Non-Patent Document 1).
JP 2003-23307 A Japanese Patent Laid-Open No. 8-114795 JP-A-9-105958 Shoichi Matsumoto and Ryo Kakuda, “Basics and Applications of Liquid Crystals”, Industrial Research Committee, May 20, 1991, Chapter 10 9.2

  In the viewing angle control display device described in Patent Document 1, the alignment film is divided into a plurality of regions of a size that can be visually recognized, and the orientations of adjacent regions are different. Therefore, when viewed from a direction other than the front, the fixed pattern is visually recognized, thereby narrowing the viewing angle. However, the viewing angle control display device described in Patent Literature 1 has a problem that information displayed on the display element can be seen through a fixed pattern when observed from an oblique direction. Moreover, since the main viewing angle is the front direction, there is a problem that it cannot be applied to cases where the main viewing angle is other than the front.

  The present invention has been made to solve the above-described problems of the prior art, and provides a viewing angle control element and a viewing angle control display device that have a high degree of light shielding in the viewing angle control direction in the viewing angle control state. The purpose is to provide.

  The viewing angle control display device according to the first aspect includes a display element and a viewing angle control element, and in a viewing angle control state, the viewing angle is controlled from a viewing-unrestricted direction inclined at a certain angle from a plane perpendicular to the display surface of the display element. A display device that allows the display element to be visually recognized, and restricts the visual recognition of the display element from a visual restriction direction that is inclined to a side opposite to the side in which the visual unrestricted direction is inclined. The control element includes a twisted nematic element, and a retardation value of the twisted nematic element is a second greater than a first range having the smallest retardation value in a predetermined range including a maximum point of vertical transmittance with respect to the retardation value. The range after the range of. Thereby, the transmittance | permeability with respect to a viewing non-restriction direction can be raised in a viewing angle control state, and a bright image can be provided. In the present invention, the vertical transmittance is the transmittance of light measured on a plane perpendicular to the display surface of the display element, and simply the transmittance is the light from various angles whose measurement angle is not limited to the vertical direction. It shall mean the transmittance of

  The viewing angle control display device according to the second aspect includes a display element and a viewing angle control element, and in a viewing angle control state, the viewing angle is controlled from a viewing-unrestricted direction inclined by a certain angle from a plane perpendicular to the display surface of the display element. A display device that allows the display element to be visually recognized, and restricts the visual recognition of the display element from a visual restriction direction that is inclined to a side opposite to the side in which the visual unrestricted direction is inclined. The control element includes a twisted nematic element, and the retardation value of the twisted nematic element is in the range of 0.9 to 1.9 μm. Thereby, the transmittance | permeability with respect to a viewing non-restriction direction can be raised in a viewing angle control state, and a bright image can be provided.

  A viewing angle control display device according to a third aspect is a viewing angle control display device including a display element and a viewing angle control element, wherein the viewing angle control element is electrically connected to a viewing angle control state and a non-viewing angle. The control state can be switched. In the viewing angle control state, the transmittance of light at an angle of + 40 ° with respect to the vertical direction from an arbitrary surface perpendicular to the viewing angle control element is 1% or less, and the tilt is −40 °. The light transmittance at the angle is 10% or more, and the light transmittance at an angle of ± 40 ° in the non-controlled state is 10% or more. Thereby, it is possible to sufficiently shield light in the direction in which the display is restricted, and display with sufficient brightness in the direction in which the display is not restricted.

  In the twisted nematic element in the viewing angle control display device according to the fourth aspect, the angle formed by the transmission polarization axis of the polarizing plate and the short axis direction of the nearest liquid crystal molecule is made narrower than the angle formed by the long axis direction of the liquid crystal molecule. ing. Thereby, in the viewing angle control state, it is possible to improve the light shielding property with respect to the viewing restriction direction, to increase the transmittance with respect to the viewing unrestricted direction, and to provide a bright image.

The viewing angle control display device according to the fifth aspect is provided with a control region in which the viewing angle can be controlled and a non-control region in which the viewing angle cannot be controlled in the display region by the display element. Thereby, since the non-control area has brightness, when the control area is in a light shielding state, the dark adaptation of the viewer can be suppressed and the light shielding effect in the control direction can be enhanced in an environment where the ambient light is dark. .
The viewing angle control element in the viewing angle control display device according to the sixth aspect includes two or more layers of twisted nematic elements that cause light shielding in the viewing restriction direction in the viewing angle control state. Thereby, it is possible to improve the light shielding property in the viewing restriction direction in the viewing angle control state.

  In the viewing angle control display device according to the seventh aspect, the twist direction of at least one twisted nematic element among the twisted nematic elements is in a reverse twist relationship with respect to the other twisted nematic elements. Accordingly, it is possible to increase the transmittance in the viewing non-limiting direction in the viewing angle control state, and to provide a bright image, and it is possible to provide an image with a small change in color depending on the viewing direction in the viewing angle non-control state.

  In the viewing angle control display device according to the eighth aspect, the twisted nematic element has a retardation value of at least one twisted nematic element in a range of 0.3 to 0.55 μm, and a retardation value of at least one twisted nematic element. Is in the range of 0.9 to 1.9 μm. Thereby, in particular, in the viewing angle control state, it is possible to increase the transmittance in the visually unrestricted direction and provide a bright image.

  In the viewing angle control display device according to the ninth aspect, the twisted nematic elements can control the viewing angle independently of each other. As a result, in an environment where the outside light is bright, it is possible to realize fine processing such as performing viewing angle control using only one layer.

  The display element in the viewing angle control display device according to the tenth aspect includes a liquid crystal display element and a backlight, and the viewing angle control element is disposed on the opposite backlight side with respect to the liquid crystal display element. Thereby, the light-shielding characteristic with respect to a visual recognition restriction | limiting direction can be improved.

  The polarizing element located between the twisted nematic elements in the viewing angle control element of the viewing angle control display device according to the eleventh aspect or between the twisted nematic element and the liquid crystal display element is shared by the two elements sandwiched. . Thereby, since the number of polarizing plates can be reduced, the transmittance | permeability fall by the light absorption of a polarizing plate can be reduced, and the utilization efficiency of light can be improved.

  In the viewing angle control display device according to the twelfth aspect, the liquid crystal display element or the nearest polarizing plate respectively included in the viewing angle control element, wherein a retardation plate is disposed between the polarizing plates. Yes. Thereby, the phase between the liquid crystal display element and the viewing angle control element can be made uniform.

  A viewing angle control display device according to a thirteenth aspect is an on-vehicle display device, and the viewing angle control element enables viewing from a passenger seat in a viewing angle control state and restricts viewing from a driver seat. To control the viewing angle. Thereby, since a display of a television image etc. can be restrict | limited to a driver's seat, safety can be improved.

  The viewing angle control element according to the fourteenth aspect transmits light in a viewing non-limiting direction inclined by a certain angle from a plane perpendicular to the main surface in the viewing angle control state, and the viewing restriction tilted to the opposite side. A viewing angle control element that shields light relative to a direction, and includes two or more layers of twisted nematic elements that cause light shielding in the viewing restriction direction in a viewing angle control state. Thereby, it is possible to improve the light shielding property in the viewing restriction direction in the viewing angle control state.

  The viewing angle control element according to the fifteenth aspect transmits light in a viewing non-restricted direction inclined at a certain angle from a plane perpendicular to the main surface in the viewing angle control state, and the viewing non-limiting direction is tilted. A viewing angle control element that shields light with respect to a viewing restriction direction inclined to the opposite side, the viewing angle control element including a twisted nematic element, and the retardation value of the twisted nematic element is a retardation value. Among the predetermined range including the maximum point of the vertical transmittance with respect to, the range after the second range is larger than the first range having the smallest retardation value. Thereby, the transmittance | permeability with respect to a visual recognition non-restriction direction can be raised in a viewing angle control state, and a bright image can be provided.

  The viewing angle control element according to the sixteenth aspect transmits light in a viewing non-restricted direction inclined at a certain angle from a plane perpendicular to the main surface in the viewing angle control state, and the viewing non-limiting direction is tilted. A viewing angle control element that shields light with respect to a viewing restriction direction that is inclined to the opposite side, the viewing angle control element including a twisted nematic element, and the retardation value of the twisted nematic element is 0.9 to The range is 1.9 μm. Thereby, the transmittance | permeability with respect to a viewing non-restriction direction can be raised in a viewing angle control state, and a bright image can be provided.

  The viewing angle control element according to the seventeenth aspect transmits light in a viewing-unrestricted direction inclined at a certain angle from a plane perpendicular to the main surface in a viewing-angle control state, and the viewing-unrestricted direction is tilted. A viewing angle control element that shields light with respect to a viewing restriction direction that is inclined to the opposite side, and the viewing angle control element can electrically switch between a viewing angle control state and a non-viewing angle control state. In the viewing angle control state, the transmittance of light at an angle of + 40 ° with respect to the vertical direction from an arbitrary plane perpendicular to the viewing angle control element is 1% or less, and the transmittance of light at an angle of −40 ° Is 10% or more, and the transmittance of light at an angle of ± 40 ° in the uncontrolled state is 10% or more. Thereby, the viewing angle can be controlled so that the display can be sufficiently shielded from the direction in which the display is limited and the display can be displayed with sufficient brightness in the direction in which the display is not limited.

  According to the present invention, it is possible to provide a viewing angle control element and a viewing angle control display device that have a high light shielding degree in the viewing angle control direction in the viewing angle control state.

  Hereinafter, embodiments to which the present invention can be applied will be described. The following description explains the embodiment of the present invention, and the present invention is not limited to the following embodiment.

  FIG. 1 is a schematic cross-sectional view of a viewing angle control display device (hereinafter simply referred to as a display device) according to the present invention. A display device 100 illustrated in FIG. 1 is a liquid crystal display device, and includes a liquid crystal display element 101, a viewing angle control element 102, and a backlight unit 103. The display device 100 according to this example is an on-vehicle display device and is used in a car navigation system. Accordingly, the display device 100 is provided at the center in the front of the four-wheeled vehicle and can be viewed from the driver seat and the passenger seat. The display device 100 displays map information in the car navigation mode, and displays video information in the television mode and the DVD mode. In FIG. 1, the upper side is the viewing side, and the lower side is the non-viewing side.

  The liquid crystal display element 101 includes a conventionally known passive matrix system such as a TN (Twisted Nematic) system and STN (Super Twisted Nematic) system, an active matrix system using a thin film transistor (TFT), or a segment system. Either is acceptable. In the liquid crystal display element 101, for example, TN, STN, IPS (In-Plane Switching), OCB (Optically Compensated Birefringence), or the like is used. On the viewing side and the non-viewing side of the liquid crystal display element 101, a polarizing film having transmission axes arranged in a predetermined direction according to the orientation direction is provided.

  The viewing angle control element 102 is an element that controls the viewing angle of the display device 100 by electrical control, and the configuration and function thereof will be described in detail later. Supply of voltage to the viewing angle control element 102 is controlled by a driving circuit (not shown) according to the mode of the car navigation system. For example, in the car navigation mode, since no voltage is supplied to the viewing angle control element 102, the viewing angle is not controlled. In the television mode or the like, a voltage is supplied to the viewing angle control element 102 to control the viewing angle. At this time, the viewing angle control element 102 restricts visual recognition from the driver's seat.

  The backlight unit 103 irradiates the liquid crystal display element 101 with back light from the non-viewing side of the liquid crystal display element 101. The backlight unit 103 includes, for example, a cold cathode tube serving as a light source, a light guide plate, a brightness enhancement film, a polarization separation film (DBEF: manufactured by 3M), and the like. Further, as a light source of the backlight unit 103, a three-wavelength LED (Laser Emitting Diode), a white organic EL (Electro Luminescence), or the like can be used.

  The liquid crystal display element 101, the viewing angle control element 102, and the backlight unit 103 may be bonded and fixed with an adhesive resin. Thereby, reflection at each member interface is reduced, a decrease in transmittance can be prevented, and light utilization efficiency can be improved.

  In the display device illustrated in FIG. 1, the viewing angle control element 102 is disposed between the liquid crystal display element 101 and the backlight unit 103, but may be disposed on the viewing side of the liquid crystal display element 101. When a self-luminous element such as a CRT (Cathode Ray Tube) or an organic EL element is used instead of the liquid crystal display element 102, the viewing angle control element 102 is disposed on the viewing side of the self-luminous element.

  Next, the configuration of the viewing angle control element 102 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of the viewing angle control element 102. In FIG. 2, the upper side is the side where the liquid crystal display element 101 is disposed, that is, the viewing side, and the lower side is the side where the backlight unit 103 is disposed, that is, the non-viewing side.

  The viewing angle control element 102 has a two-layer structure of a first TN (twisted nematic) element 1021 and a second TN (twisted nematic) element 1022. In the present invention, the light shielding characteristics can be improved by making the TN device have a two-layer structure in this way. The light shielding characteristics can be further improved by laminating three or more TN elements. A polarizing plate 21 is provided on the viewing side of the first TN element 1021, a polarizing plate 22 is provided between the first TN element 1022 and the second TN element 1022, and a polarizing plate 23 is provided on the non-viewing side of the second TN element 1022. Is provided. These polarizing plates 21, 22, and 23 are polarizing films each having a transmission axis arranged in a predetermined direction. A thin TAC (triacetate) polarizing plate may be used as the polarizing plates 21, 22, and 23.

  In the configuration example shown in FIG. 2, the number of polarizing plates 22 between the first TN element 1021 and the second TN element 1022 is one, and the first TN element 1021 and the second TN element 1022 share the polarizing plate. Not only this but two polarizing plates may be provided between both.

  Further, a liquid crystal display element 101 is provided on the viewing side of the viewing angle control element 102 as shown in FIG. 1, and a polarizing plate is provided on both the viewing side and the non-viewing side of the liquid crystal display element 101 as well. Although necessary, the polarizing plate 21 provided on the viewing side of the viewing angle control element 102 may be shared with the polarizing plate to be provided on the non-viewing side of the liquid crystal display element 101. In this case, one polarizing plate is provided between the first TN element 1021 and the transparent substrate of the liquid crystal display element 101. According to such a configuration, the liquid crystal display element 101 and the viewing angle control element 102 do not overlap with the polarizing plate, and the number of polarizing plates can be reduced, so that a decrease in transmittance due to the absorption of the polarizing plate is suppressed. In addition, the light use efficiency can be improved.

  Further, when the viewing angle control element 102 is arranged on the viewing side of the liquid crystal display element 101, the polarizing plate 23 on the non-viewing side of the second TN element 1022 can be shared with the liquid crystal display element 101. Therefore, even in such an arrangement, it is possible to prevent a decrease in transmittance due to light absorption of the polarizing plate and improve the light utilization efficiency.

  Furthermore, when the light emitted from the backlight unit 103 has a polarization property, the polarizing plate closest to the backlight unit 103 (the polarizing plate 23 in the example shown in FIG. 2) may not be provided. Thereby, the transmittance | permeability fall by a polarizing plate can be reduced and the utilization efficiency of light can be improved.

  In the first TN element 1021, the TN liquid crystal 51 is sandwiched between the two transparent substrates 11 and 12, and the outer periphery thereof is sealed with the seal material 6. The transparent substrates 11 and 12 are made of glass or transparent resin. Electrodes 31 and 32 are respectively formed on one side of the transparent substrates 11 and 12. The electrodes 31 and 32 are formed of, for example, a transparent electrode such as ITO. By applying a predetermined voltage between the electrode 31 and the electrode 32 by a drive circuit (not shown), the arrangement of liquid crystal molecules in the TN liquid crystal 51 can be changed, and transmission / blocking of light incident from the backlight unit 103 can be controlled.

  Further, alignment films 41 and 42 are stacked on the electrodes 31 and 32. The alignment films 41 and 42 are provided to control the alignment of the TN liquid crystal 51. The alignment films 41 and 42 are formed by, for example, printing a polyimide organic film on the surfaces of the transparent substrates 11 and 12 on which the electrodes 31 and 32 are formed, and subjecting the surface of the organic film to a rubbing process, thereby aligning anisotropy. It is formed by producing.

  The second TN element 1022 has the same configuration as the first TN element 1021, and includes transparent substrates 13 and 14, electrodes 33 and 34, alignment films 43 and 44, a TN liquid crystal 52, and a seal material 6. A predetermined voltage can be applied between the electrode 33 and the electrode 34, whereby the arrangement of liquid crystal molecules in the TN liquid crystal 52 can be changed, and transmission / blocking of light incident from the backlight unit 103 can be controlled.

  The transmission axis of the polarizing plate (not shown) provided on the non-viewing side in the liquid crystal display element 101 is different from the transmission axis of the polarizing plate 21 provided on the viewing side of the first TN element 1021 in the viewing angle control element 102. In this case, a retardation film, that is, a retardation plate (not shown) may be disposed between the polarizing plate of the liquid crystal display element 101 and the polarizing plate 21 of the viewing angle control element 102. The retardation plate can rotate the direction of linearly polarized light and align the transmission axes of both polarizing plates.

  Next, the axial arrangement of each optical system in the viewing angle control element 102 will be described with reference to FIG. 3A is a polarizing plate 21, FIG. 3B is a first TN element 1021, FIG. 3C is a polarizing plate 22, FIG. 3D is a second TN element 1022, and FIG. 3E is a polarizing plate. The respective absorption axis arrangements of 23 are shown. The axis angle of the liquid crystal molecule at the center of the first TN element 1021 is a reference line (dotted line in the drawing), and the counterclockwise direction is a positive number. 3B and 3D showing the axial arrangement of the first TN element 1021 and the second TN element 1022, F indicates the alignment axis of the alignment films 41 and 43 on the viewing side, and R indicates the alignment film 42 on the anti-viewing side. , 44 orientation axes.

  As shown in FIG. 3A, when the absorption axis angle of the polarizing plate 21 is θ1, θ1 is set to 135 to 140 ° or 40 to 45 °, more preferably 137 to 140 ° or 40 to 43 °. Set to Thereby, it becomes possible to improve the transmittance ratio in the viewing-restricted direction and the viewing-unrestricted direction in the present invention using the viewing angle control element. In other words, it can improve the light blocking rate in the viewing angle control direction, achieve a high light blocking rate in a wide range of the viewing angle control direction, and suppress the decrease in the transmittance in the non-viewing angle control direction, thereby controlling the viewing angle. This is because the performance as an element can be improved.

  Also, as shown in FIG. 3B, when the axis angle of the orientation axis on the viewing side of the first TN element 1021 is θ2, θ2 is set to 120 to 155 ° or 25 to 60 °, more preferably, It is set to 135 to 145 ° or 35 ° to 45 °. Further, when the twist angle from the orientation direction on the viewing side to the orientation direction on the non-viewing side is φ2, φ2 is set to 50 to 120 ° or −50 to −120 °, more preferably 70 to 90 ° or −70. It is set to -90 °. The retardation value Δn 2 · d 2, which is the product of the refractive index anisotropy of the liquid crystal molecules (measurement light wavelength 589 nm, hereinafter the same) Δn 2 and the thickness d 2 of the liquid crystal layer, is in the first range 0.3 to 0.55 μm. The second range is set to 0.9 to 1.3 μm or the third range is set to 1.3 to 1.9 μm, and more preferably the second range is set to 0.9 to 1.3 μm. By setting the retardation value Δn 2 · d 2 to the second range, the transmittance in the visual non-limiting direction can be increased as compared to the case where the retardation value is set to the first range, and more than the case where the retardation value Δn 2 · d 2 is set to the third range. This is because the light-shielding property in the viewing restriction direction can be improved.

  As shown in FIG. 3C, when the axial angle of the polarizing plate 22 is θ3, θ3 is set to 40 to 45 ° or 135 to 140 °, more preferably 40 to 43 ° or 137 to 140 °. Is set. This is because, similarly to the setting of θ1, it is possible to achieve both a high light-shielding rate in a wide range in the viewing-restricted direction and prevention of a decrease in transmittance in the viewing-unrestricted direction, and to improve the performance as a viewing angle control element.

  As shown in FIG. 3D, when the axis angle of the orientation axis on the viewing side of the second TN element 1022 is θ4, θ4 is set to 25-60 ° or 120-155 °, more preferably 35-45. Or set to 135 to 145 °. When the twist angle from the orientation direction on the viewing side to the orientation direction on the non-viewing side is φ4, φ4 is set to −50 to −120 ° or 50 to 120 °, more preferably −70 to −90 ° or It is set to 70 to 90 °. The retardation value Δn4 · d4, which is the product of the refractive index anisotropy Δn4 of the liquid crystal molecules and the thickness d4 of the liquid crystal layer, has a first range of 0.3 to 0.55 μm and a second range of 0.9 to It is set to 1.3 μm or the third range 1.3 to 1.9 μm, more preferably to the second range 0.9 to 1.3 μm. As shown in FIG. 3E, when the axial angle of the polarizing plate 23 is θ5, θ5 is set to 135 to 140 ° or 40 to 45 °, more preferably 137 to 140 ° or 40 to 43 °. Is set.

  As shown in FIGS. 3B and 3D, the twist directions of the first TN element 1021 and the second TN element 1022 are set to a reverse twist relationship. Thereby, the angle dependency of the color depending on the viewing direction is reduced, and the color evaluation value ΔE * can be reduced. At that time, by setting | φ2 | = | φ4 | and 70 ° ≦ | φ2 | (= | φ4 |) <90 °, it is possible to realize a high light shielding degree in the viewing angle control direction in the viewing angle control state. it can. In addition, the crossing angle of the polarizing plate axis angle in a normal TN device is 90 °, but when viewed from an oblique direction, the crossing angle is effectively 90 ° or more. Since this causes light leakage, the degree of light shielding from an oblique direction can be improved by setting the crossing angle of the polarizing plates to less than 90 °. In particular, the crossing angle of the polarizing plates is preferably 80 ° to 86 °.

FIG. 4 shows the axial arrangement of the optical system in the viewing angle control element having a three-layer structure.
4A shows a polarizing plate 21, FIG. 4C shows a polarizing plate 22, FIG. 4E shows a polarizing plate 23, and FIG. The axis angle of the liquid crystal molecule at the center of the first TN element 1021 is a reference line (dotted line in the drawing), and the counterclockwise direction is a positive number. Further, in FIGS. 4B, 4D, and 4F showing the axial arrangement of the first TN element 1021, the second TN element 1022, and the third TN element 1023, F indicates the alignment axis of the alignment film on the viewing side, and R indicates anti-viewing. This represents the orientation axis of the side orientation film.

  As shown in FIG. 4A, when the absorption axis angle of the polarizing plate 21 is θ1, θ1 is set to 135 to 140 ° or 40 to 45 °, more preferably 137 to 140 ° or 40 to 43 °. Set to Thereby, it becomes possible to improve the transmittance ratio in the viewing-restricted direction and the viewing-unrestricted direction in the present invention using the viewing angle control element. That is, the light shielding rate in the viewing restriction direction can be improved, and a high light shielding rate can be achieved in a wide range in the viewing restriction direction. This is because the performance can be improved.

  Further, as shown in FIG. 4B, when the axial angle of the orientation axis on the viewing side of the first TN element 1021 is θ2, θ2 is set to 120 to 155 ° or 25 to 60 °, more preferably, It is set to 135 to 145 ° or 35 ° to 45 °. Further, when the twist angle from the orientation direction on the viewing side to the orientation direction on the non-viewing side is φ2, φ2 is set to 50 to 120 ° or −50 to −120 °, more preferably 70 to 90 ° or −70. It is set to -90 °. The retardation value Δn 2 · d 2, which is the product of the refractive index anisotropy of the liquid crystal molecules (measurement light wavelength 589 nm, hereinafter the same) Δn 2 and the thickness d 2 of the liquid crystal layer, is in the first range 0.3 to 0.55 μm. The second range is set to 0.9 to 1.3 μm or the third range is set to 1.3 to 1.9 μm, and more preferably the second range is set to 0.9 to 1.3 μm. By setting the retardation value Δn 2 · d 2 to the second range, the transmittance in the visual non-limiting direction can be increased as compared to the case where the retardation value is set to the first range, and more than the case where the retardation value Δn 2 · d 2 is set to the third range. This is because the light-shielding property in the viewing restriction direction can be improved.

  As shown in FIG. 4C, when the axial angle of the polarizing plate 22 is θ3, θ3 is set to 40 to 45 ° or 135 to 140 °, more preferably 40 to 43 ° or 137 to 140 °. Is set. This is because, similarly to the setting of θ1, it is possible to achieve both a high light blocking ratio in a wide range with respect to the viewing restriction direction and prevention of a decrease in transmittance in the viewing non-limiting direction, and the performance as a viewing angle control element can be improved.

  As shown in FIG. 4D, when the axis angle of the orientation axis on the viewing side of the second TN element 1022 is θ4, θ4 is set to 25-60 ° or 120-155 °, more preferably 35-45. Or set to 135 to 145 °. When the twist angle from the orientation direction on the viewing side to the orientation direction on the non-viewing side is φ4, φ4 is set to −50 to −120 ° or 50 to 120 °, more preferably −70 to −90 ° or It is set to 70 to 90 °. The retardation value Δn4 · d4, which is the product of the refractive index anisotropy Δn4 of the liquid crystal molecules and the thickness d4 of the liquid crystal layer, has a first range of 0.3 to 0.55 μm and a second range of 0.9 to It is set to 1.3 μm or the third range 1.3 to 1.9 μm, more preferably to the second range 0.9 to 1.3 μm. As shown in FIG. 4E, when the axial angle of the polarizing plate 23 is θ5, θ5 is set to 135 to 140 ° or 40 to 45 °, more preferably 137 to 140 ° or 40 to 43 °. Is set. As shown in FIG. 4F, when the axial angle of the polarizing plate 23 is θ6, θ6 is set to 120 to 155 ° or 25 to 60 °, more preferably 135 to 145 ° or 35 ° to 45 °. Set to Further, when the twist angle from the orientation direction on the viewing side to the orientation direction on the non-viewing side is φ6, φ6 is set to 50 to 120 ° or −50 to −120 °, more preferably 70 to 90 ° or −70. It is set to -90 °. The retardation value Δn6 · d6, which is the product of the refractive index anisotropy Δn6 of the liquid crystal molecules and the thickness d6 of the liquid crystal layer, has a first range of 0.3 to 0.55 μm and a second range of 0.9 to It is set to 1.3 μm or the third range 1.3 to 1.9 μm, more preferably to the second range 0.9 to 1.3 μm. As shown in FIG. 4G, when the axial angle of the polarizing plate 23 is θ7, θ7 is set to 40 to 45 ° or 135 to 140 °, more preferably 40 to 43 ° or 137 ° to 140 °. Set to

  As shown in FIGS. 4B, 4D, and 4F, the twist directions of the first TN element 1021 and the second TN element 1022 and the second TN element 1022 and the third TN element 1023 are set in a reverse twist relationship. Thereby, the angle dependency of the color depending on the viewing direction is reduced, and the color evaluation value ΔE * can be reduced. At that time, by setting | φ2 | = | φ4 | = | φ6 | and 70 ° ≦ | φ2 | (= | φ4 | = | φ6 |) <90 °, the viewing angle control direction in the viewing angle control state is set. A high degree of shading can be realized. In addition, the crossing angle of the polarizing plate axis angle in a normal TN device is 90 °, but when viewed from an oblique direction, the crossing angle is effectively 90 ° or more. Since this causes light leakage, the degree of light shielding from an oblique direction can be improved by setting the crossing angle of the polarizing plates to less than 90 °. In particular, the crossing angle of the polarizing plates is preferably 80 ° to 86 °.

  Next, the operation of the viewing angle control element 102 will be described. When a predetermined voltage is applied between the electrodes 31 and 32, the liquid crystal molecules in the first TN element 1021 change its direction in the same direction as the electric field in accordance with the change in the electric field. Since the liquid crystal molecules in the first TN element 1021 have positive dielectric anisotropy, the alignment is changed so as to be perpendicular to the main surfaces of the two substrates 11 and 12. Further, when a predetermined voltage is applied between the electrodes 33 and 34, the liquid crystal molecules in the second TN element 1022 change its direction in the same direction as the electric field in accordance with the change of the electric field. Since the liquid crystal molecules in the second TN element 1022 have positive dielectric anisotropy, the alignment is changed so as to be perpendicular to the main surfaces of the two substrates 13 and 14. Note that liquid crystal molecules can be similarly used with negative dielectric anisotropy.

  Next, control of the viewing angle control element 102 according to the present invention will be described with reference to FIG. The viewing angle control element 102 can take two states regarding the viewing angle control, that is, a non-control state and a control state. As shown in FIG. 5A, when the viewing angle control element 102 is in an uncontrolled state, the display device 100 including the viewing angle control element 102 is tilted by −40 ° from the normal to the main surface. The display of the liquid crystal display element 101 is observed both when observed from the direction (hereinafter referred to as a viewing-unrestricted direction) and when observed from the same direction inclined by + 40 ° (hereinafter referred to as the viewing-restricted direction). Can do. At this time, the viewing angle control element 102 transmits the emitted light from the backlight unit 102 and supplies it to the liquid crystal display element 101 in both the viewing-unrestricted direction and the viewing-restricted direction. For example, when the display device 100 is a display device of a car navigation system, the visual unrestricted direction is assumed to be the direction of the line of sight when a person sitting in the passenger seat visually recognizes the screen of the display device 100. Further, the visual restriction direction is assumed to be the direction of the line of sight when a person sitting in the driver's seat visually recognizes the screen of the display device 100. When displaying a map information display screen for operating car navigation, the viewing angle control element 102 is set to a non-control state, and the display screen can be viewed from both the passenger seat and the driver seat.

  As shown in FIG. 5 (b), when the viewing angle control element 102 is in the viewing angle control state, the display device 100 including the viewing angle control element 102 is viewed from the viewing-unrestricted direction. Although the display of the liquid crystal display element 101 can be visually recognized, the display of the liquid crystal display element 101 cannot be visually recognized when observed from the viewing restriction direction. At this time, the viewing angle control element 102 transmits the light emitted from the backlight unit 103 to the liquid crystal display element 101 through the viewing-unrestricted direction, but shields it from the viewing-unrestricted direction. . For example, when the display device 100 is a display device of a car navigation system, the viewing angle control element 102 is in a control state when displaying a display screen of video information (viewing restriction information) such as a television image or a DVD image. The video information can be viewed from the passenger seat, but the video information cannot be viewed from the driver seat.

  As described above, when the viewing angle control element 102 is in the viewing angle control state, the screen becomes dark with respect to the viewing restriction direction, and the display on the liquid crystal display element 101 cannot be viewed, but the ambient light is dark. When the viewer's eyes get used to the darkness in the environment, the display image may be gradually visible. Therefore, the display device 100 according to the present invention can employ a configuration for reliably suppressing viewing of the display image from the viewing restriction direction.

  As shown in FIG. 6, when the display device 100 is viewed from the front, a casing 201, that is, a frame is visually recognized around the periphery, and a rectangular display screen 300 is visually recognized inside thereof. The rectangular display screen 300 is provided with a viewing angle control region 301 and a viewing angle non-control region 302. The viewing angle control area 301 is a rectangular area spaced inward from the outermost periphery of the display screen 300 by a fixed distance, and is an area where the viewing angle can be controlled. In the viewing angle control region 301, the viewing angle control element 102 can be set to either a non-control state or a control state by electrical control.

  The non-control region 302 is a constant region located between the housing 201 and the viewing angle control region 301, and is a region where the viewing angle cannot be controlled. In the viewing angle non-control region 302, the light emitted from the backlight unit 103 is supplied to the liquid crystal display element 101 as it is. For this reason, the viewing angle non-control region 302 is bright even when the viewing angle control element 102 is in the controlled state and the display screen 300 is hardly visible from the viewing restriction direction. Visible. Thus, since some viewing angle non-control regions 302 in the display screen 300 are in a bright state, even if the viewing angle control element 102 is recognized dark from the viewing restriction direction, the viewer's eyes It becomes difficult to get used to the darkness. For example, even when the display device 100 is a display device of a car navigation system and video information such as a television image is displayed on the display device, the video information may be viewed from the driver's seat. Since the viewing angle non-control area 302 has a certain brightness, the video information displayed in the viewing angle restriction area 301 cannot be viewed.

  In the example shown in FIG. 6, the viewing angle non-control region 302 is provided so as to surround the entire periphery of the viewing angle control region 301 without any interruption, but the present invention is not limited to this. Good. Further, the viewing angle non-control region 302 may be provided in an arbitrary region on the display screen 300, or may be provided in an arbitrary number of regions. Furthermore, the viewing angle non-control region 302 may be an arbitrary pattern, and the pattern may indicate a character or a symbol. For example, the shape of the viewing angle non-control region 302 may be a logo pattern of a company that manufactures and sells car navigation systems. In this case, when the viewing angle control element 102 is set to the control state, the logo is visually recognized from the driver's seat.

  Next, the relationship between the retardation value Δnd of the TN element and the vertical transmittance will be described. FIG. 7 is a graph showing the relationship between the retardation value Δnd of the TN element and the vertical transmittance, and FIG. 8 is a diagram for explaining the conditions under which the observation was performed. As shown in FIGS. 8A, 8B, and 8C, the first polarizing plate, the TN element, and the second polarizing plate are stacked in this order from the viewing side. The arrows in FIGS. 8A and 8C each indicate the absorption axis. In FIG. 8, θ1 = 45 °, θ2 = 45 °, θ3 = 135 °, φ2 = 90 °, and Δnd2 = (variable).

  As shown in FIG. 7, as the retardation value Δnd increases from 0 to 0.3 μm, the vertical transmittance increases almost monotonously. However, the initial transmission is 0.3 to 0.55 μm indicated by R1 in the figure. It has a maximum point (peak). The range up to the next minimum point including this maximum point is the first range described above. Moreover, it has the following maximum point in 0.9-1.3 micrometer shown by R2 of a figure, The range to the next minimum point including this maximum point is the 2nd range mentioned above. Furthermore, it has the following maximum point in 1.3-1.9 micrometers shown by R3 of a figure, The range to the next minimum point including this maximum point is the 3rd range mentioned above.

  In the viewing angle control element according to the present invention, any retardation value in the first range, the second range, and the third range shown in FIG. 7 may be used. A second range that is excellent in the balance of transparency in the viewing-unrestricted direction in the angle control state and light-shielding property in the viewing-restricted direction in the viewing angle control state is preferable.

  Here, the viewing angle characteristics of the TN element will be described with reference to FIG. FIG. 9A shows a simulation of the viewing angle characteristics of the TN element. As can be seen from the line C1 showing the same contrast, the viewing angle characteristics from a certain angle (here, 90 ° side) are shown in FIG. Are better.

  FIG. 9B shows the optical characteristics of the TN element, and plots the change in transmittance with respect to the viewing angle both when the predetermined voltage is applied to the TN element and when it is not applied. . As shown in FIG. 9B, in a state where a predetermined voltage is not applied, the transmittance is 30% or more from −40 ° to + 40 °, whereas a predetermined voltage is applied. In this state, the transmittance is 15% or less from -40 ° to + 40 °. When a predetermined voltage is applied to the TN element, the transmittance is about 10 to 15% in the vicinity of −40 °, whereas the transmittance is several percent or less at 0 ° to + 40 °. It stays and is almost in a light-shielded state. That is, the TN element has anisotropy in the transmittance when a predetermined voltage is applied, and the transmittance is completely different between the direction of the viewing angle of −40 ° and the direction of + 40 °. A certain amount of light is transmitted, and the latter does not transmit most light. In the present invention, viewing angle control is realized by utilizing the characteristics of the TN device.

  Then, the Example and comparative example of this invention are demonstrated. In the description of each example, the axial arrangement of each optical system in the viewing angle control element is determined by the parameters specified in FIG. In each example, the angle θ1 of the absorption axis of the polarizing plate 21 is a fixed value (135 °) in order to coincide with the alignment axis of the liquid crystal display element. The axis angle of the liquid crystal molecule long axis at the center of the first TN element 1021 in the viewing angle control element is a reference line (illustrated dotted line), and the counterclockwise direction is a positive number.

  The display device according to each example is an in-vehicle display device and has the configuration shown in FIG. Such a display device is attached in front of the driver seat and the passenger seat, and is controlled to be shielded from being visible from the driver seat in the viewing angle control state.

  Among Examples 1 to 15 described below, Examples 1 to 12 are transmittance values of viewing angle control elements, and Examples 13 to 15 are brightness values of viewing angle control devices attached to the display panel. . Moreover, the transmittance | permeability of Example 5, 6, 9 and 10 and the color evaluation value of Examples 7 and 8 are the values calculated by simulation, and others are actual measurement values.

Example 1.
In the viewing angle control element according to Example 1, in the viewing angle control state, the axial arrangement of the optical system was determined for the purpose of improving the light shielding on the wide angle direction side with respect to the driver's seat. For this reason, the crossing angle of the polarizing plate was set narrow. In addition, the viewing angle control element according to Example 1 has a two-layer structure of a first TN element and a second TN element, each retardation Δnd is in a first range (0.3 to 0.55 μm), and The twist angle was 70 °.

  The axial arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 40 °, θ4 = 35 °, θ5 = 140 °, φ2 = 70 °, φ4 = −70 °, and the retardation value is Δn2 · d2 = 0. .446 μm and Δn 4 · d 4 = 0.446 μm.

  In the non-controlled state, the viewing angle control element having such a configuration had a transmittance of 26.2% in the −40 ° direction and a transmittance of 25.9% in the 40 ° direction. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 15.7%, and the transmittance with respect to the 40 ° direction was 0.014%. When the contrast was defined as (transmittance in the direction of −40 °) / (transmittance in the direction of 40 °), the contrast of this example in the control state was 1121.

  10A shows the change in transmittance in the uncontrolled state, FIG. 10B shows the change in transmittance in the controlled state, and FIG. 10C shows the change in transmittance with respect to the driver seat in the controlled state. Are shown for Example 1, Example 2, and Example 3, respectively.

Example 2.
In the viewing angle control element according to Example 2, the retardation Δnd was increased in order to increase the luminance for the passenger seat in the viewing angle control state. In addition, the viewing angle control element according to Example 2 has a two-layer structure of a first TN element and a second TN element, each retardation value Δnd is in a second range (0.9 to 1.3 μm), and twisted The angle was 80 °.

  The axial arrangement is θ1 = 135 °, θ2 = 140 °, θ3 = 40 °, θ4 = 40 °, θ5 = 140 °, φ2 = 80 °, φ4 = −80 °, and the retardation value is Δn2 · d2 = 1. 0.000 μm and Δn 4 · d 4 = 1.00 μm.

  In the viewing angle control element having such a configuration, the transmittance in the −40 ° direction was 23.9% and the transmittance in the 40 ° direction was 22.1% in an uncontrolled state. Further, in the control state of the viewing angle, the transmittance in the −40 ° direction was 25.6%, and the transmittance in the 40 ° direction was 0.010%. The contrast of this example in the controlled state was 2560.

  Thus, in the viewing angle control element according to Example 2, the transmittance with respect to the direction of −40 ° in the viewing angle control state was 25.6%, which was clearly improved from the transmittance of 15.7% in Example 1. . 10B also shows that the viewing angle control element according to Example 2 has higher transmittance in the vicinity of −40 ° than Example 1. FIG.

Example 3
The viewing angle control element according to Example 3 has a single-layer structure including the polarizing plate 21, the first TN element 1021, and the polarizing plate 22 in FIG. 2, and the retardation value Δnd in the first TN element 1021 is set to the first range (0. 3 to 0.55 μm) and the twist angle was 70 °.

  The axial arrangement was θ1 = 135 °, θ2 = 145 °, θ3 = 42 °, φ2 = 70 °, and the retardation value was Δn2 · d2 = 0.446 μm. The contrast of this example in the control state was 62.

  In the viewing angle control element having such a configuration, the transmittance in the -40 ° direction was 35.8% and the transmittance in the 40 ° direction was 35.1% in the uncontrolled state. Further, in the control state of the viewing angle, the transmittance in the −40 ° direction was 27.3%, and the transmittance in the 40 ° direction was 0.44%.

  Thus, in the viewing angle control element according to Example 3, the transmittance with respect to the direction of 40 ° in the viewing angle control state is 0.44%, which is higher than the transmittance of 0.014% in Example 1. It was. Therefore, in order to ensure that video information such as a TV image cannot be visually recognized from the driver's seat, it is possible to adopt a two-layer structure as in Example 1 rather than adopting a one-layer structure as in Example 3. It turned out to be preferable. FIG. 10C also shows that the transmittance in the vicinity of 40 ° in Example 3 is higher than that in Example 1.

Example 4
The viewing angle control element according to Example 4 has a two-layer structure of a first TN element and a second TN element for the purpose of improving the light shielding degree in the driver's seat, and the retardation value Δnd is set in the first range (0.3 to 0.55 μm) and the twist angle was 70 °.

  The axial arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 45 °, θ4 = 35 °, θ5 = 135 °, φ2 = 70 °, φ4 = −70 °, and the retardation value is Δn2 · d2 = 0. .446 μm and Δn 4 · d 4 = 0.446 μm.

  In the viewing angle control element having such a configuration, the transmittance in the −40 ° direction was 25.9% and the transmittance in the 40 ° direction was 27.2% in the non-controlled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 18.8%, and the transmittance with respect to the 40 ° direction was 0.005%. The contrast of this example in the control state was 3917.

  11A shows the change in transmittance in the uncontrolled state, FIG. 11B shows the change in transmittance in the controlled state, and FIG. 11C shows the change in transmittance with respect to the driver seat in the controlled state. Are shown for Example 3 and Example 4, respectively. As can be seen from FIG. 11A, in the uncontrolled state, Example 3 having a single-layer structure has higher transmittance than Example 4 having a two-layer structure. According to FIG. 11 (b), it can be seen that, on the passenger seat side, the transmittance of Example 3 having a single layer structure is higher than that of Example 4 having a two layer structure. According to FIG. 11C, it can be seen that, on the driver's seat side, the transmittance of Example 4 with the two-layer structure is lower than that of Example 3 with the one-layer structure, and the light shielding property is higher.

  Further, in the viewing angle control element according to Example 4, the axial angle θ3 of the polarizing plate 22 is 45 ° and the axial angle θ5 of the polarizing plate 23 is 135 °, whereas in the viewing angle control element according to Example 1, The axial angle θ3 of the polarizing plate 22 is 40 ° and the axial angle θ5 of the polarizing plate 23 is 140 °, which has a narrow-axis structure. 12A shows the change in transmittance in the uncontrolled state, FIG. 12B shows the change in transmittance in the controlled state, and FIG. 12C shows the change in transmittance with respect to the driver seat in the controlled state. Are shown for Example 1 and Example 4, respectively. As can be seen from the figure, the light shielding property on the driver's seat side is higher in Example 1 having the narrow shaft structure than in Example 4.

Example 5.
The viewing angle control element according to Example 5 has a small twist angle for the purpose of improving the light shielding degree in the driver's seat. The viewing angle control element has a two-layer structure of a first TN element and a second TN element, the retardation value Δnd is in the first range (0.3 to 0.55 μm), and the twist angle is 70 °. did.

  The axial arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 45 °, θ4 = 35 °, θ5 = 135 °, φ2 = 70 °, φ4 = −70 °, and the retardation value is Δn2 · d2 = 0. 408 μm and Δn 4 · d 4 = 0.408 μm.

  In the viewing angle control element having such a configuration, the transmittance in the -40 ° direction was 26.8% and the transmittance in the 40 ° direction was 26.5% in an uncontrolled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 21.9%, and the transmittance with respect to the 40 ° direction was 0.021%. The contrast of this example in the control state was 1043.

Example 6
The viewing angle control element according to Example 6 has a two-layer structure of a first TN element and a second TN element, the retardation value Δnd is in the first range (0.3 to 0.55 μm), and the twist angle is 90 °. It was.

  The axial arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 45 °, θ4 = 35 °, θ5 = 135 °, φ2 = 90 °, φ4 = −90 °, and the retardation value is Δn2 · d2 = 0. 408 μm and Δn 4 · d 4 = 0.408 μm.

  In the viewing angle control element having such a configuration, the transmittance in the −40 ° direction was 26.7% and the transmittance in the 40 ° direction was 26.7% in an uncontrolled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 20.9%, and the transmittance with respect to the 40 ° direction was 0.219%. The contrast of this example in the controlled state was 95.

  13A shows the change in transmittance in the uncontrolled state, FIG. 13B shows the change in transmittance in the controlled state, and FIG. 13C shows the change in transmittance with respect to the driver seat in the controlled state. Are shown for Example 5 and Example 6, respectively. According to FIG. 13A, it can be seen that in the non-control state, the transmittance is almost the same between Example 5 of 70 ° twist and Example 6 of 90 ° twist. According to FIG. 13 (b), it can be seen that the 90 ° twist example 6 is slightly lower than the 70 ° twist example 5 on the passenger seat side. According to FIG. 13C, it can be seen that the example 5 of the 70 ° twist on the driver's seat side has a lower transmittance than the example 6 of the 90 ° twist and has superior light shielding properties.

Example 7.
The viewing angle control element according to Example 7 has a two-layer structure of a first TN element and a second TN element having an inverted twist structure, the retardation value Δnd is in the first range (0.3 to 0.55 μm), and the twist The angle was 70 °.

  The axial arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 45 °, θ4 = 35 °, θ5 = 135 °, φ2 = 70 °, φ4 = −70 °, and the retardation value is Δn2 · d2 = 0. .454 μm and Δn 4 · d 4 = 0.454 μm.

  In the viewing angle control element having such a configuration, the transmittance in the −40 ° direction was 24.3% and the transmittance in the 40 ° direction was 26.1% in the uncontrolled state. Further, in the controlled viewing angle, the transmittance in the −40 ° direction was 25.3%, and the transmittance in the 40 ° direction was 0.093%. The contrast of this example in the control state was 272.

Example 8
The viewing angle control element according to Example 8 has a two-layer structure of a first TN element and a second TN element having a forward twist structure, the retardation value Δnd is in the first range (0.3 to 0.55 μm), and the twist The angle was 70 °.

  The axial arrangement is θ1 = 135 °, θ2 = 215 °, θ3 = 45 °, θ4 = −35 °, θ5 = 135 °, φ2 = 70 °, φ4 = 70 °, and the retardation value is Δn2 · d2 = 0. .454 μm and Δn 4 · d 4 = 0.454 μm.

  In the viewing angle control element having such a configuration, the transmittance in the -40 ° direction was 24.9% and the transmittance in the 40 ° direction was 24.7% in the uncontrolled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 22.4%, and the transmittance with respect to the 40 ° direction was 0.091%. The contrast of this example in the control state was 246.

  14A shows the change in transmittance in the uncontrolled state, FIG. 14B shows the change in transmittance in the controlled state, and FIG. 14C shows the change in transmittance with respect to the driver seat in the controlled state. (D) shows the change in the color evaluation value in the viewing angle non-controlled state for Example 7 and Example 8, respectively. According to FIG. 14A, in the non-control state, it can be seen that the reverse twist example 7 and the forward twist example 8 have almost the same transmittance in the range of −40 ° to + 40 °. However, in the range of −40 ° or less and + 40 ° or more, the reverse twist example 7 has higher transmittance. According to FIG. 14B, it can be seen that in the control state, the reverse twist example 7 has higher transmittance than the forward twist example 8 on the passenger seat side. According to FIG. 14 (c), it can be seen that the forward twist example 8 and the reverse twist example 7 have the same transmittance and substantially the same light shielding performance on the driver side. According to FIG. 14D, it can be seen that the forward twist example 8 has a higher hue evaluation value ΔE * than the reverse twist example 7, and the angle dependency due to the viewing position of the hue is larger.

Example 9.
In the viewing angle control element according to Example 9, the angle formed by the transmission axis of the polarizing plate and the minor axis direction of the closest liquid crystal molecule is within a narrower angle range than the major axis direction, and 2 of the first TN element and the second TN element. It has a layer structure, the retardation value Δnd is in the first range (0.3 to 0.55 μm), and the twist angle is 70 °. That is, light incident on the first TN element and the second TN element is incident on the minor axis direction of the liquid crystal molecules in these elements.

  The axial arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 45 °, θ4 = 35 °, θ5 = 135 °, φ2 = 70 °, φ4 = −70 °, and the retardation value is Δn2 · d2 = 0. .423 μm and Δn 4 · d 4 = 0.423 μm.

  In the viewing angle control element having such a configuration, the transmittance in the −40 ° direction was 26.8% and the transmittance in the 40 ° direction was 26.7% in the non-controlled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 13.2%, and the transmittance with respect to the 40 ° direction was 0.019%. The contrast of this example in the control state was 695.

Example 10
In the viewing angle control element according to Example 10, the angle formed by the transmission axis of the polarizing plate and the major axis direction of the closest liquid crystal molecule is set within a range of angles narrower than the minor axis direction, and 2 of the first TN element and the second TN element. It has a layer structure, the retardation value Δnd is in the first range (0.3 to 0.55 μm), and the twist angle is 70 °. That is, the light incident on the first TN element and the second TN element is incident in the major axis direction of the liquid crystal molecules in these elements.

  The axial arrangement is θ1 = 135 °, θ2 = 215 °, θ3 = 45 °, θ4 = −35 °, θ5 = 135 °, φ2 = −70 °, φ4 = 70 °, and the retardation value is Δn2 · d2 = 0.423 μm and Δn4 · d4 = 0.423 μm.

  In the viewing angle control element having such a configuration, the transmittance in the −40 ° direction was 25.6% and the transmittance in the 40 ° direction was 22.7% in the non-controlled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 8.50%, and the transmittance with respect to the 40 ° direction was 0.016%. The contrast of this example in the control state was 531.

  15A shows the change in transmittance in the uncontrolled state, FIG. 15B shows the change in transmittance in the controlled state, and FIG. 15C shows the change in transmittance with respect to the driver seat in the controlled state. Are shown for Example 9 and Example 10, respectively. According to FIG. 15A, in the non-control state, it can be seen that the transmittance is almost the same in the range of −40 ° to + 40 ° in Example 9 in the short axis direction and Example 10 in the long axis direction. However, in the range of −40 ° or less and + 40 ° or more, Example 9 in the minor axis direction has higher transmittance than Example 10 in the major axis direction. According to FIG. 15 (b), it can be seen that in the control state, the transmittance in the minor axis example 9 is higher than that in the major axis example 10 on the passenger seat side. According to FIG. 15C, it can be seen that the light shielding performance on the driver's seat side is almost the same in Example 9 in the minor axis direction and Example 10 in the major axis direction.

Example 11
The viewing angle control element according to Example 11 has a three-layer structure of a first TN element, a second TN element, and a third TN element (see FIG. 4), and has a retardation value Δnd in the first range (0.3 to 0.55 μm). ) And the twist angle was 70 °.

  The shaft arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 40 °, θ4 = 35 °, θ5 = 140 °, θ6 = 145 °, θ7 = 40 °, φ2 = 70 °, φ4 = −70 ° Φ6 = 70 °, and retardation values were Δn 2 · d 2 = 0.446 μm, Δn 4 · d 4 = 0.446 μm, and Δn 6 · d 6 = 0.446 μm.

In the viewing angle control element having such a configuration, the transmittance in the -40 ° direction was 16.7% and the transmittance in the 40 ° direction was 14.4% in the non-controlled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 11.0%, and the transmittance with respect to the 40 ° direction was 0.001%. The contrast of this example in the controlled state was 8462.
FIG. 16 shows the transmittance characteristics of Example 1 having a two-layer structure and Example 11 having a three-layer structure. As shown in the figure, the transmittance is lowered by using the three-layer structure, but the light shielding property can be improved.

Example 12.
The viewing angle control element according to Example 12 has a three-layer structure of a first TN element, a second TN element, and a third TN element (see FIG. 4), and has a retardation value Δnd in the second range (0.9 to 1.3 μm). ) And the twist angle was 80 °.

  The shaft arrangement is θ1 = 135 °, θ2 = 140 °, θ3 = 40 °, θ4 = 40 °, θ5 = 140 °, θ6 = 140 °, θ7 = 40 °, φ2 = 80 °, φ4 = −80 ° Φ6 = 80 °, and retardation values were Δn 2 · d 2 = 1.000 μm, Δn 4 · d 4 = 1.000 μm, and Δn 6 · d 6 = 1.000 μm.

  In the viewing angle control element having such a configuration, the transmittance in the -40 ° direction was 16.7% and the transmittance in the 40 ° direction was 14.4% in the non-controlled state. Further, in the control state of the viewing angle, the transmittance with respect to the −40 ° direction was 18.4%, and the transmittance with respect to the 40 ° direction was 0.000%. The contrast of this example in the control state was 317241.

  FIG. 17 shows the transmittance characteristics of Example 11 having a three-layer structure and a retardation value in the first range, and Example 12 having a three-layer structure and a retardation value in the second range. FIG. 17A shows the change in transmittance in the uncontrolled state, FIG. 17B shows the change in transmittance in the controlled state, and FIG. 17C shows the change in transmittance with respect to the driver seat in the controlled state. Are shown for Example 11 and Example 12, respectively. In particular, as shown in FIG. 17 (b), by setting the retardation value to the second range, it was possible to increase the luminance with respect to the front passenger seat in the viewing angle control state.

Example 13
In the viewing angle control display device according to Example 13, the viewing angle control element has a three-layer structure of a first TN element, a second TN element, and a third TN element (see FIG. 4), and the retardation value Δnd is set to a first range ( 0.3 to 0.55 μm) and the twist angle was 70 °. In particular, in the viewing angle control display device according to Example 13, the viewing angle control element is disposed on the non-viewing side of the liquid crystal display element. That is, the liquid crystal display element, the viewing angle control element, and the backlight unit were arranged in this order from the viewing side.

  The shaft arrangement is θ1 = 135 °, θ2 = 145 °, θ3 = 40 °, θ4 = 35 °, θ5 = 140 °, θ6 = 145 °, θ7 = 40 °, φ1 = 70 °, φ3 = −70 ° Φ5 = 70 °, and retardation values were Δn 2 · d 2 = 0.446 μm, Δn 4 · d 4 = 0.446 μm, Δn 6 · d 6 = 0.446 μm. In addition, the display element and the backlight in this example were those of a Panasonic TV car (TR-T70W3). This display element is active matrix drive using TFT, and the liquid crystal mode is TN.

In the viewing angle control display device having such a configuration, the luminance in the −40 ° direction was 122 cd / m ² and the luminance in the 40 ° direction was 122 cd / m ² in the uncontrolled state. In the viewing angle control state, the luminance with respect to the direction of −40 ° was 46.5 cd / m ² , and the luminance with respect to the direction of 40 ° was 0.0249 cd / m ² . The luminance ratio was 1867.

Example 14
In the viewing angle control display device according to Example 14, the viewing angle control element has a three-layer structure of a first TN element, a second TN element, and a third TN element (see FIG. 4), and the retardation value Δnd is set to a first range ( 0.3 to 0.55 μm) and the twist angle was 70 °. In particular, in the viewing angle control display device according to Example 14, the viewing angle control element is arranged on the viewing side of the liquid crystal display element. That is, the viewing angle control element, the liquid crystal display element, and the backlight unit were arranged in this order from the viewing side.

  The shaft arrangement is θ1 = 140 °, θ2 = 145 °, θ3 = 40 °, θ4 = 35 °, θ5 = 140 °, θ6 = 145 °, θ7 = 45 °, φ2 = 70 °, φ4 = −70 ° Φ6 = 70 °, and retardation values were Δn 2 · d 2 = 0.446 μm, Δn 4 · d 4 = 0.446 μm, and Δn 6 · d 6 = 0.446 μm. In addition, the display element and the backlight in this example were those of a Panasonic TV car (TR-T70W3). This display element is active matrix drive using TFT, and the liquid crystal mode is TN.

In the viewing angle control display device having such a configuration, the luminance in the −40 ° direction was 118 cd / m ² and the luminance in the 40 ° direction was 117 cd / m ² in the uncontrolled state. Further, in the viewing angle control state, the luminance with respect to the direction of −40 ° was 48.6 cd / m ² , and the luminance with respect to the direction of 40 ° was 0 cd / m ² .

  FIG. 18 shows the luminance characteristics of Example 13 in which the viewing angle control element is disposed on the non-viewing side of the liquid crystal display element and Example 14 in which the viewing angle control element is disposed on the viewing side of the liquid crystal display element. As shown in the figure, particularly as shown in FIG. 18C, the light shielding state of the driver's seat is improved by arranging the viewing angle control element on the viewing side of the liquid crystal display element.

Example 14
The viewing angle control element according to Example 14 has a three-layer structure of a first TN element, a second TN element, and a third TN element (see FIG. 4), and has a retardation value Δnd in the second range (0.9 to 1.3 μm). ) And the twist angle was 80 °. In particular, in Example 15, the viewing angle control element is arranged on the viewing side of the liquid crystal display element. That is, the viewing angle control element, the liquid crystal display element, and the backlight unit were arranged in this order from the viewing side.

  The shaft arrangement is θ1 = 140 °, θ2 = 140 °, θ3 = 40 °, θ4 = 40 °, θ5 = 140 °, θ6 = 140 °, θ7 = 45 °, φ2 = 80 °, φ4 = −80 ° Φ6 = 80 °, and retardation values were Δn 2 · d 2 = 1.00 μm, Δn 4 · d 4 = 1.00 μm, and Δn 6 · d 6 = 1.00 μm. In addition, the display element and the backlight in this example were those of a Panasonic TV car (TR-T70W3). This display element is active matrix drive using TFT, and the liquid crystal mode is TN.

In the viewing angle control display device having such a configuration, the luminance in the −40 ° direction was 114 cd / m ² and the luminance in the 40 ° direction was 108 cd / m ² in the uncontrolled state. Further, in the viewing angle control state, the luminance with respect to the −40 ° direction was 50.1 cd / m ² , and the luminance with respect to the 40 ° direction was 0 cd / m ² .

  FIG. 19 shows the luminance characteristics of Example 14 in which the retardation value is in the first range and Example 15 in which the retardation value is in the second range. In particular, as shown in FIG. 19 (b), by setting the retardation value to the second range, it was possible to increase the luminance with respect to the passenger seat in the viewing angle control state.

It is a schematic sectional drawing of the viewing angle control display apparatus concerning this invention. It is a schematic sectional drawing of the viewing angle control element concerning this invention. It is an axis arrangement diagram of each optical system in the viewing angle control element according to the present invention. It is an axis arrangement diagram of each optical system in the viewing angle control element according to the present invention. It is explanatory drawing for demonstrating control of the viewing angle control element concerning this invention. It is a front view of the viewing angle control display apparatus concerning this invention. It is a graph which shows the relationship between the retardation value of a TN element, and vertical transmittance. FIG. 10 is an axis layout diagram for explaining preconditions of the graph shown in FIG. 9. It is a figure which shows the viewing angle characteristic and optical characteristic of a TN element. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability of the viewing angle control element concerning the example regarding this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability of the viewing angle control element concerning the example regarding this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability of the viewing angle control element concerning the example regarding this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability of the viewing angle control element concerning the example regarding this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability of the viewing angle control element concerning the example regarding this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability of the viewing angle control element concerning the example regarding this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability of the viewing angle control element concerning the example regarding this invention. It is a graph which shows the relationship between the viewing angle of the viewing angle control apparatus concerning the example regarding this invention, and the transmittance | permeability. It is a graph which shows the relationship between the viewing angle of the viewing angle control display apparatus concerning the example regarding this invention, and a brightness | luminance. It is a graph which shows the relationship between the viewing angle of the viewing angle control display apparatus concerning the example regarding this invention, and a brightness | luminance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Viewing angle control display apparatus 101 Liquid crystal display element 102 Viewing angle control element 103 Backlight unit 21, 22, 23, 24 Polarizing plate 11, 12, 13, 14 Transparent substrate 31, 32, 33, 34 Electrode 41, 42, 43 , 44 Alignment film 51, 52 TN liquid crystal 1021 First TN element 1022 Second TN element 1023 Third TN element

Claims (17)

The display element and the viewing angle control element are provided, and in the viewing angle control state, the display element can be viewed from an unrestricted viewing direction inclined by a certain angle from a plane perpendicular to the display surface of the display element. A display device that restricts visual recognition of the display element from a visual restriction direction that is inclined to a side opposite to a side in which the visual recognition non-restricted direction is inclined,
The viewing angle control element includes a twisted nematic element, and the retardation value of the twisted nematic element is larger than the first range having the smallest retardation value in a predetermined range including the maximum point of the vertical transmittance with respect to the retardation value. A viewing angle control display device having a range after the large second range. The display element and the viewing angle control element are provided, and in the viewing angle control state, the display element can be viewed from an unrestricted viewing direction inclined by a certain angle from a plane perpendicular to the display surface of the display element. A display device that restricts visual recognition of the display element from a visual restriction direction that is inclined to a side opposite to a side in which the visual recognition non-restricted direction is inclined,
The viewing angle control element includes a twisted nematic element, and a retardation value of the twisted nematic element is in a range of 0.9 to 1.9 μm. A viewing angle control display device comprising a display element and a viewing angle control element,
The viewing angle control element can be electrically switched between a viewing angle control state and a non-viewing angle control state, and is tilted by + 40 ° with respect to the vertical direction from an arbitrary plane perpendicular to the viewing angle control element in the viewing angle control state. The transmittance of light at an angle is 1% or less, the transmittance of light at an angle of −40 ° is 10% or more, and the transmittance of light at an angle of ± 40 ° in an uncontrolled state is 10%. The viewing angle control display device as described above. The twisted nematic device has a narrower angle formed by the transmission polarization axis of the polarizing plate and the short axis direction of the closest liquid crystal molecule than the long axis direction of the liquid crystal molecule.
The viewing angle control display device according to claim 1, 2 or 3. In the display area by the display element, a control area where the viewing angle can be controlled and a non-control area where the viewing angle cannot be controlled are provided.
5. A viewing angle control display device according to claim 1, 2, 3 or 4. The viewing angle control element includes two or more twisted nematic elements that cause light shielding in the viewing restriction direction in a viewing angle control state.
6. A viewing angle control display device according to claim 1, 2, 3, 4 or 5. The twist direction of at least one twisted nematic element among the twisted nematic elements is in a reverse twist relationship with respect to the other twisted nematic elements.
The viewing angle control display device according to claim 6. The twisted nematic element has a retardation value of at least one twisted nematic element in a range of 0.3 to 0.55 μm, and a retardation value of at least one twisted nematic element in a range of 0.9 to 1.9 μm.
The viewing angle control display device according to claim 6 or 7. The twisted nematic elements can control the viewing angle independently of each other.
The viewing angle control display device according to claim 6, 7 or 8. The display element includes a liquid crystal display element and a backlight,
The viewing angle control element is disposed on the opposite backlight side with respect to the liquid crystal display element.
The viewing angle control display device according to claim 1. Shared between the two elements sandwiched between the twisted nematic elements in the viewing angle control element, or between the twisted nematic element and the liquid crystal display element,
The viewing angle control display device according to claim 6. The liquid crystal display element or the polarizing plate closest to each of the viewing angle control elements,
A retardation plate is disposed between each polarizing plate,
The viewing angle control display device according to claim 11. The viewing angle control display device is an in-vehicle display device,
The viewing angle control element enables viewing from the passenger seat in the viewing angle control state, and controls the viewing angle to limit the viewing from the driver seat;
The viewing angle control display device according to claim 1. A viewing angle control element that transmits light in a viewing-unrestricted direction inclined by a certain angle from a plane perpendicular to the main surface in a viewing-angle control state and blocks light in a viewing-restricted direction inclined to the opposite side Because
A viewing angle control element comprising two or more twisted nematic elements that cause light shielding in the viewing restriction direction in a viewing angle control state. In the viewing angle control state, light is transmitted in a viewing-unrestricted direction inclined by a certain angle from a plane perpendicular to the main surface, and in a viewing-restricted direction inclined to the side opposite to the side where the viewing-unrestricted direction is inclined. A viewing angle control element that blocks light,
The viewing angle control element includes a twisted nematic element, and the retardation value of the twisted nematic element is smaller than the first range having the smallest retardation value in a predetermined range including the maximum point of the vertical transmittance with respect to the retardation value. A viewing angle control element in a range after the large second range. In the viewing angle control state, light is transmitted in a viewing-unrestricted direction inclined by a certain angle from a plane perpendicular to the main surface, and in a viewing-restricted direction inclined to the side opposite to the side where the viewing-unrestricted direction is inclined. A viewing angle control element that blocks light,
The viewing angle control element includes a twisted nematic element, and a retardation value of the twisted nematic element is in a range of 0.9 to 1.9 μm. In the viewing angle control state, light is transmitted in a viewing-unrestricted direction inclined by a certain angle from a plane perpendicular to the main surface, and in a viewing-restricted direction inclined to the side opposite to the side where the viewing-unrestricted direction is inclined. A viewing angle control element that blocks light,
The viewing angle control element can be electrically switched between a viewing angle control state and a non-viewing angle control state, and is tilted by + 40 ° with respect to the vertical direction from an arbitrary plane perpendicular to the viewing angle control element in the viewing angle control state. The transmittance of light at an angle is 1% or less, the transmittance of light at an angle of −40 ° is 10% or more, and the transmittance of light at an angle of ± 40 ° in an uncontrolled state is 10% or more. A viewing angle control display element.

Images