JP2005265920A - Electro-optical device, electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-optical device having a configuration capable of controlling a viewing angle range to an arbitrary angle without impairing transmittance, that is, without impairing display brightness.
The electro-optical device of the present invention is an electro-optical device having a viewing angle control element 2 and a display element 1, and the viewing angle control element 2 includes a liquid crystal layer, and the liquid crystal layer contributes to display. It is characterized in that it can be switched between a state in which the light to be transmitted is transmitted with scattering and a state in which it is transmitted without being relatively scattered.
[Selection] Figure 1

Description

  The present invention relates to an electro-optical device and an electronic apparatus.

In general, an image display device provided in a word processor, a personal computer, or the like displays various information on a screen and displays an operation result of an operator. In this type of image display device, The display brightness, contrast ratio, viewing angle, etc. are designed according to the purpose. In recent years, when work content is highly confidential, or when using computers, mobile phones, etc. in public places such as trains and buses, a means for concealing display images from surrounding people other than the operator is provided. There is an increasing demand for image display devices. In such an application, even if high display performance is provided, the place of use is restricted, or the use is performed while paying attention to the surroundings, which may cause inconvenience in use. Therefore, for the purpose of improving the confidentiality of the display image, an optical element for controlling the viewing angle of the display device and a display device including the optical element have been proposed (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 10-197844

  The display device described in Patent Document 1 has a guest-host type liquid crystal element as a viewing angle control optical element (viewing angle control element) in front of a display element such as a liquid crystal panel. However, although the viewing angle control element in this case can arbitrarily control the viewing angle range in accordance with the applied voltage, light is absorbed during the control, so that the transmittance is reduced and the display brightness is lowered. It was an end.

  The present invention has been made to solve the above-described problems, and is an electric device having a configuration capable of controlling the viewing angle range to an arbitrary angle without impairing transmittance, that is, without impairing display brightness. An object is to provide an optical device and an electronic apparatus including the optical device.

  Next, in order to solve the above-described problem, the electro-optical device of the present invention includes a liquid crystal layer, and the liquid crystal layer transmits light contributing to display with scattering, as compared with the state. The display device includes a viewing angle control element configured to be able to switch between a state in which light is transmitted without being relatively scattered and a display element.

  According to such an electro-optical device, the angle of light contributing to display can be arbitrarily controlled by the viewing angle control element, that is, the wide viewing angle mode when the viewing angle control element transmits light without scattering. When the viewing angle control element transmits light without scattering, the display can be switched in the narrow viewing angle mode. Furthermore, since light absorption does not occur with such a viewing angle control, there is no problem that the brightness of the display is reduced, and a bright display with low power consumption can be realized. Specifically, when the electro-optical device is viewed by a large number of people, the viewing angle control element is set to a wide viewing angle mode, while when the electro-optical device is viewed in a state where secrecy is ensured, The viewing angle control element can be set to the narrow viewing angle mode.

  In the viewing angle control element of the present invention, the liquid crystal layer may be configured to be able to switch between the states based on a change in voltage applied to the liquid crystal layer. In this case, the viewing angle can be arbitrarily controlled according to the applied voltage. Specifically, a liquid crystal layer (PDLC (Polymer-Dispersed Liquid Crystal)) composed of a polymer-dispersed liquid crystal (PDLC) can be employed as the liquid crystal layer. Examples include a dispersed type, and a type in which a polymer is dispersed in a three-dimensional network or in the form of fine droplets in a liquid crystal continuous phase. An element using such a polymer dispersion type liquid crystal can switch between a transmission state and a scattering state without using a polarizer, and can switch between liquid crystal molecules when no voltage is applied or when a voltage is applied. While the arrangement changes and the refractive index changes, the arrangement of the polymer as a dispersion medium does not change and the refractive index does not change.

  In the electro-optical device according to the aspect of the invention, it is possible that the liquid crystal layer of the viewing angle control element is configured to be able to switch the states based on a change in voltage applied to the liquid crystal layer. In this case, the viewing angle can be arbitrarily controlled according to the applied voltage. Specifically, the liquid crystal layer can be composed of a polymer dispersed liquid crystal. According to the polymer dispersed liquid crystal, transmission and scattering are suitably controlled according to the applied voltage. It becomes possible.

  The electro-optical device according to the aspect of the invention further includes an illumination device, and the viewing angle control element is disposed between the display element and the illumination device, and performs transmissive display based on light transmitted through the viewing angle control element. It can be configured. In this case, the viewing angle control element is configured such that the liquid crystal layer can be switched between a state in which light from the light source is transmitted with scattering and a state in which light is relatively transmitted without scattering, respectively. The display element is configured to perform selective transmission display based on the light transmitted through the viewing angle control element. On the other hand, the electro-optical device of the present invention further includes an illumination device and a reflecting member, the viewing angle control element is disposed between the display element and the illumination device, and the light emitted from the illumination device is It is also possible to transmit in the order of the viewing angle control means and the display element and then be reflected by the reflecting member, and then pass through the display element, the viewing angle control means and the illumination device in this order.

  In addition, the said illuminating device shall emit parallel light. In this case, when the viewing angle control element is in a state of transmitting light without scattering, the viewing angle of display is narrowed, and when it is in a state of transmitting light with scattering, the viewing angle of display is widened.

  Further, the viewing angle control element can be of a matrix drive type configuration. In this case, only a specific part of the display surface can be selectively widened or narrowed, and either a passive matrix drive or an active matrix drive is adopted as a specific configuration. Can do.

  Next, in order to solve the above problem, an electronic apparatus according to the present invention includes the electro-optical device. According to such an electronic apparatus, the visual state of the information can be freely controlled by the visual angle control function of the visual angle control element, so that the information can be easily concealed for a third party, It is possible to provide good information visibility to a person.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
1 and 2 are schematic diagrams conceptually showing the configuration of the display device according to the present embodiment. FIG. 1 shows a narrow viewing angle mode state, and FIG. 2 shows a wide viewing angle mode state. Note that the display device of the present embodiment is a liquid crystal display device and includes the viewing angle control element and the illumination device according to the present invention.

  The liquid crystal display device 100 according to the present embodiment includes a liquid crystal display element 1, a viewing angle control element 2, and a backlight (light source) 3. The backlight 3 emits parallel light and has a main light source unit and a light guide unit (not shown). The viewing angle control element 2 converts the light from the backlight 3 to an arbitrary angle and transmits it. The light after passing through the viewing angle control element 2 enters the liquid crystal display element 1 and the liquid crystal The light transmitted through the display element 1 is used for display.

  Here, the liquid crystal display device 100 is configured to be able to arbitrarily control the display viewing angle based on the operation of the viewing angle control element 2, and is configured to be capable of predetermined transmissive display based on the operation of the liquid crystal display element 1. ing. Therefore, the viewing angle control element 2 and the backlight 3 function as the illumination device of the liquid crystal display device 100 of the present embodiment. Hereinafter, the configuration and operation of the viewing angle control element 2 will be described.

  The viewing angle control element 2 is configured to be able to change the light from the backlight 3 to an arbitrary angle. Specifically, as shown in FIG. 3, a liquid crystal layer is interposed between a pair of translucent substrates 21 and 22. 25, and one solid transparent electrode 23, 24 is formed on the inner surface side of each of the substrates 21, 22. The liquid crystal layer 25 is composed of polymer-dispersed liquid crystal (PDLC), and is composed of a type in which the liquid crystal 26 is dispersed in the polymer matrix 27 as fine droplets. . Each of the electrodes 23 and 24 is connected to a power source 29 as voltage applying means, and is applied with a predetermined voltage.

  In such a viewing angle control element 2, as shown in FIG. 3A, the liquid crystal molecules 26 are randomly oriented in the polymer matrix 27 when the switch of the power source 29 is opened and no voltage is applied. Due to the difference in refractive index, the light incident on the viewing angle control element 2 is scattered and emitted. On the other hand, as shown in FIG. 3B, when the switch of the power source 29 is closed and a predetermined voltage is applied between the electrodes 23 and 24, the liquid crystal molecules 26 are aligned in the electric field direction. When viewed from above, the refractive index becomes equal, and the light incident on the viewing angle control element 2 is emitted without being scattered.

  That is, according to the viewing angle control element 2 used in the present embodiment, it is possible to selectively take both the transmission state and the scattering state without using a polarizer, and at the time of no voltage application or voltage application, While the arrangement of liquid crystal molecules changes and the refractive index thereof changes, the arrangement of the polymer serving as a dispersion medium does not change, and the viewing angle can be controlled by utilizing the fact that the refractive index does not change. Specifically, the liquid crystal layer 25 is configured to be able to switch between a state of transmitting light with scattering as described above and a state of transmitting light without relatively scattering.

  When the liquid crystal layer 25 of the viewing angle control element 2 is in a state of transmitting light without scattering, the liquid crystal display device 100 has a narrow viewing angle mode, that is, a range in which display can be visually recognized as shown in FIG. It becomes a mode. On the other hand, when the liquid crystal layer 25 of the viewing angle control element 2 is in a state of transmitting light with scattering, the liquid crystal display device 100 has a wide viewing angle mode, that is, a mode in which the display can be visually recognized as shown in FIG. It becomes.

  On the other hand, the liquid crystal display element 3 performs selective transmission display using light from the backlight 3 that has passed through the viewing angle control element 2. For example, a TN mode liquid crystal layer is sandwiched between a pair of substrates. Can be adopted.

  According to the liquid crystal display device 100 of the present embodiment as described above, the angle of light that contributes to display can be arbitrarily controlled by the viewing angle control element 2, that is, the state in which the viewing angle control element 2 transmits light without scattering. The display can be switched in the wide viewing angle mode (FIG. 2), and in the narrow viewing angle mode (FIG. 1) when the viewing angle control element 2 transmits light without scattering. In this case, light absorption does not occur with viewing angle control, so that a bright display with low power consumption can be realized without a decrease in display brightness. Specifically, when the liquid crystal display device 100 is viewed by a large number of people, the viewing angle control element 2 is set to the wide viewing angle mode, while the liquid crystal display device 100 is viewed in a state where secrecy is ensured. The viewing angle control element 2 may be set to the narrow viewing angle mode.

  In the embodiment shown in FIGS. 1 to 3, an example in which the viewing angle control element 2 is disposed between the backlight 3 and the liquid crystal display element 1 has been shown. However, for example, a liquid crystal display device 100 a shown in FIG. 4 is used. In addition, the viewing angle control element 2 may be disposed on the display surface side of the liquid crystal display element 1, that is, on the side different from the backlight 3 of the liquid crystal display element 1.

  In the embodiment shown in FIGS. 1 to 3, the backlight 3 is disposed on the back side of the liquid crystal display element 1 (the side different from the display surface). For example, the liquid crystal display device shown in FIG. As in 100b, a front light (light source) 30 may be disposed closer to the display surface than the liquid crystal display element 1. In this case, the front light 30 includes a main light source 31 and a light guide unit 32. The light guide unit 32 reflects light from the main light source 31 to the back side (the liquid crystal display element 1 side), while the back side ( The light from the liquid crystal display element 1 side) is emitted to the display surface side.

  That is, in the liquid crystal display device 100b having the configuration of FIG. 5, the front light 30 is disposed on the display surface side of the liquid crystal display element 1, and further, aluminum or the like is formed on the opposite side of the liquid crystal display element 1 from the display surface. A reflecting plate 4 is provided. In this case, the viewing angle control element 2 is disposed between the front light 30 and the liquid crystal display element 1.

  As described above, the viewing angle control element 2 according to the present invention is also applied to the liquid crystal display device 100b having the front light 30 disposed on the display surface side of the liquid crystal display element 1, so that the display viewing angle is arbitrarily set. It is supposed to be possible. Specifically, the light reflected from the front light 30 to the back side passes through the viewing angle control element 2 (with scattering in FIG. 5) and enters the liquid crystal display element 1. The liquid crystal display element 1 performs selective transmission, and the light transmitted through the liquid crystal display element 1 is reflected by the reflecting plate 4, and is transmitted again through the liquid crystal display element 1 and the viewing angle control element 2 for display.

  Next, FIG. 6 shows a modification of the viewing angle control element. The viewing angle control element 200 shown in FIG. 6 has a matrix drive type (passive matrix drive) configuration, and stripe electrodes 28 and 29 intersecting each other are arranged on the inner surfaces of the pair of substrates 21 and 22. That is, the electrode 28 is configured as a stripe electrode extending in the direction perpendicular to the paper surface, and the electrode 29 is configured as a stripe electrode extending in the horizontal direction on the paper surface.

  According to such a viewing angle control element 200, only a specific portion of the display surface can be selectively widened or narrowed. Note that one of the electrodes may be a matrix pixel electrode and the other electrode may be a solid common electrode for active matrix driving.

  FIG. 7 is a perspective view showing an example of an electronic apparatus according to the invention. A cellular phone 1300 shown in this figure includes the display device of the present invention as a small-sized display portion 1301 and includes a plurality of operation buttons 1302, an earpiece 1303, and a mouthpiece 1304.

  The liquid crystal display device described above is not limited to the above mobile phone, but an electronic book, a personal computer, a digital still camera, a liquid crystal television, a viewfinder type or a monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, It can be suitably used as an image display means for a word processor, a workstation, a video phone, a POS terminal, a device equipped with a touch panel, etc., and in any electronic device, switching between a wide viewing angle and a narrow viewing angle can be performed very easily. It is possible to display information with excellent information confidentiality and high quality.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this, and the present invention is not limited to the wording of each claim without departing from the scope described in each claim. Improvements based on the knowledge that a person skilled in the art normally has can be added as appropriate to the extent that the person can easily replace them.

  For example, in the present embodiment, a liquid crystal display device is used as the display device, but the viewing angle control element of the present invention can also be applied to, for example, a self-luminous organic EL device or a plasma display device. That is, by providing the viewing angle control element of the present invention on the display surface side of the self-luminous display device, the viewing angle of the display can be appropriately controlled.

  In this embodiment, the viewing angle control element is provided with a polymer dispersed liquid crystal. However, a phase transition type cholesteric liquid crystal or a dynamic scattering mode (DSM) liquid crystal can also be used. It is also possible to configure the viewing angle control element by shifting between isotropic and anisotropy.

  In this embodiment, a transmissive liquid crystal display device is shown. However, the configuration of the present invention can be applied to a transflective liquid crystal display device.

The schematic diagram which shows one Embodiment of the display apparatus of this invention notionally. The schematic diagram which shows notionally the state by which the display apparatus of FIG. 1 was mode-converted. The schematic diagram which shows one Embodiment of the viewing angle control element of this invention notionally. The schematic diagram which shows notionally the modification of the display apparatus of this invention. The schematic diagram which shows notionally the modification of the display apparatus of this invention. The schematic diagram which shows one Embodiment of the viewing angle control element of this invention notionally. FIG. 11 is a perspective view illustrating an embodiment of an electronic apparatus according to the invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Display element (liquid crystal display element), 2 ... Viewing angle control element, 3 ... Backlight (light source), 25 ... Liquid crystal layer

Claims (8)

  A liquid crystal layer is provided, and the liquid crystal layer can be switched between a state in which light contributing to display is transmitted with scattering and a state in which light is transmitted without scattering relative to the state. An electro-optical device having a viewing angle control element and a display element.   The viewing angle control element according to claim 1, wherein the liquid crystal layer is configured to be able to switch the states based on a change in voltage applied to the liquid crystal layer.   The viewing angle control element according to claim 2, wherein the liquid crystal layer is composed of polymer dispersed liquid crystal. A lighting device;
The viewing angle control element is disposed between the display element and the illumination device, and is configured to perform transmissive display based on light transmitted through the viewing angle control element. The display device according to any one of claims 1 to 3. A lighting device and a reflective member;
The viewing angle control element is disposed between the display element and the lighting device,
The light emitted from the illumination device is transmitted in the order of the viewing angle control unit and the display element, reflected by the reflecting member, and then transmitted in the order of the display element, the viewing angle control unit, and the illumination device. The electro-optical device according to any one of claims 1 to 3, wherein   The electro-optical device according to claim 4, wherein the illumination device emits parallel light.   The electro-optical device according to claim 1, wherein the viewing angle control element has a matrix drive type configuration.   An electronic apparatus comprising the electro-optical device according to claim 1.

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