JP2006064882A - Display device, viewing angle controller, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device which can maintain the display quality and overlap another image on the displayed image to conceal it when viewing from a specific direction by changing the display mode in a simple configuration. <P>SOLUTION: The display device 4 has the main LCD14, a SW-LCD12 disposed in the path of the light passing through the main LCD14 to electrically switch the image into the single image display mode and the multiple image display mode, a 1st polarizer plate 13, and a 2nd polarizer plate 11. The liquid crystal molecules in the liquid crystal layer 23 of the SW-LCD12 are oriented so that the long axial direction when projecting from the direction the substrates 21 and 22 cross each other perpendicularly is almost parallel with the polarizing direction of the light passing through the 1st polarizer plate. And at least some of the liquid crystal layer 23 are oriented to make their long axial directions almost parallel with the above substrate in the single image display mode, but oriented to incline against the substrate in the multiple image display mode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display device and a viewing angle control device, and more particularly to a display device and a viewing angle control device that can be switched to a mode in which an image that is visually recognized varies depending on the viewing direction.

  In recent years, electronic devices have been made lighter, and electronic devices having a display such as mobile phones and mobile personal computers can be taken out and used in public places. In this case, there has been a problem that confidential documents and information to be personally viewed can be seen by people nearby.

  In response to this problem, there has been proposed a display device that can normally be set to a wide viewing angle display mode and can be switched to a narrow viewing angle display mode when being taken out to a public place. The narrow viewing angle mode is a mode in which a normal display image can be viewed from the front of the display where the user is present, and a plain image or another image can be viewed from an oblique direction. In addition, by enabling switching to the wide viewing angle display mode, it is possible to cope with a case where a wide viewing angle is required, such as when a photographed image is desired to be viewed by a large number of people.

  As a component for performing such display, for example, the viewing angle variable element disclosed in Patent Document 1 is such that a liquid crystal layer between a pair of substrates is aligned with liquid crystal molecules in a direction perpendicular to the substrates. It has a narrow viewing angle and a wide viewing angle by being oriented in the parallel direction. Patent Document 2 describes a viewing angle changing means for changing the viewing angle of the information display means by changing the orientation of the liquid crystal between two glass plates.

In addition, by dividing the display device into several sections and changing the liquid crystal alignment direction etc. in each section, what is displayed on the display when viewing the display from a direction other than the front in the narrow viewing angle mode There is also a configuration in which another image different from that is visible. For example, Patent Document 3 discloses a liquid crystal display device in which an alignment film sandwiching a liquid crystal layer is partitioned into a plurality of regions, and the alignment directions of adjacent regions are different. Patent Document 4 discloses a liquid crystal display device in which first liquid crystal cells and second liquid crystal cells having different viewing angle directions are alternately arranged.
JP-A-9-105958 (release date: April 22, 1997) JP 2004-62094 (release date: February 26, 2004) JP 2001-264768 (release date: September 26, 2001) JP-A-2004-38035 (Release date: February 5, 2004)

  However, in the configuration of Patent Document 1 described above, the refractive index is changed by vertically aligning liquid crystal molecules to form a narrow viewing angle mode. However, the viewing angle control using such a refractive index improves the display quality of an image. Difficult to keep.

  Patent Document 2 describes that the viewing angle of the display is controlled by changing the orientation of the liquid crystal, but does not describe how to change the orientation of the liquid crystal. Control cannot be realized.

  Furthermore, although the configuration of Patent Document 3 describes that a fixed pattern unrelated to the display signal is visually recognized from directions other than the front direction, it is structurally viewed from the right direction and the pattern viewed from the right direction. Since the monochrome pattern is reversed from the viewed pattern, the display image cannot be properly hidden when viewed from a direction other than the front direction. In other words, if the non-transparent area is increased when viewed from the right direction, the transmissive area increases when viewed from the left direction. It can only be made difficult to see by covering an image like a houndstooth with half the area.

  In addition, the configuration of Patent Document 4 is a configuration in which a large number of small liquid crystal cells are arranged in an array plate, but such a liquid crystal display device has a complicated configuration and is difficult to manufacture.

  As described above, there is no known display device with a simple configuration that has a high display quality and can switch modes so that a display image can be appropriately hidden from an oblique line of sight.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a display device that can maintain display quality with a simple configuration and can hide a display image from a specific direction by mode switching. Is to realize.

  In order to solve the above problems, a display device according to the present invention includes a display switching unit for electrically switching a visually recognized image to a single image display mode and a multiple image display mode, and the display switching unit. In a display device comprising: a first polarizing unit that makes linearly polarized light in a certain direction incident; and a second polarizing unit that takes out linearly polarized light in a certain direction out of light emitted from the display switching unit, the display switching unit includes a pair of A liquid crystal layer disposed between the substrates, and the major axis direction of the liquid crystal molecules when the liquid crystal molecules of the liquid crystal layer are projected from a direction orthogonal to the substrate and the linear polarization direction of light incident on the liquid crystal molecules are always The second polarizing means takes out linearly polarized light emitted from the liquid crystal molecules, and at least some of the liquid crystal molecules in the liquid crystal layer are in a single image display mode. The liquid crystal molecules are aligned so that the major axis direction is substantially parallel to or substantially perpendicular to the substrate. In the multi-image display mode, the major axis direction is tilted with respect to the substrate. It is a feature.

  Here, the inclination means that it is neither parallel nor perpendicular to a certain direction or a certain plane.

  For example, the major axis direction of the liquid crystal molecules of the liquid crystal element is included in a plane formed by the direction of the transmission axis or absorption axis of the first polarizing means and the traveling direction of light, and the liquid crystal molecules This is a configuration that can take a state where the direction is substantially perpendicular or substantially parallel to the light traveling direction and a state inclined with respect to the light traveling direction.

  In other words, in the single screen display mode, the major axis direction of the liquid crystal molecules of the liquid crystal layer is substantially parallel to the substrate and substantially parallel to or substantially perpendicular to the polarization transmission axis of the first polarizing means, and a plurality of images are displayed. In the mode, the single screen display mode is tilted in the direction perpendicular to the substrate. Alternatively, the major axis direction of the liquid crystal molecules of the liquid crystal layer is substantially perpendicular to the substrate in the single screen display mode, and from the state of the single screen display mode in the multiple image display mode, It is inclined in a plane substantially parallel or substantially perpendicular to the polarization transmission axis and perpendicular to the substrate.

  According to this, the light incident on the display switching unit becomes linearly polarized light in a certain direction by the first polarizing unit. Further, in the liquid crystal layer of the display switching means, the major axis direction when the liquid crystal molecules are projected from the direction orthogonal to the substrate is always substantially parallel or substantially perpendicular to the polarization direction of the light transmitted through the first polarizing means. Oriented.

  When the polarization direction of linearly polarized light incident on the liquid crystal layer and the major axis direction when liquid crystal molecules are projected from a certain direction are parallel or perpendicular, birefringence does not occur in the liquid crystal layer when viewed from this direction. . Therefore, not limited to the selected mode, birefringence does not occur in the liquid crystal layer viewed from a direction parallel to the plane drawn by the dots on the liquid crystal molecules due to orientation change (hereinafter referred to as “from the front direction”). Thus, for example, the polarization transmission axes of the first polarizing means and the second polarizing means are set to the same direction, or the linearly polarized light emitted from the first polarizing means is aligned with the transmission axis of the second polarizing means. By installing a member that rotates and enters the second polarizing means, if the linearly polarized light in the same direction as the first polarizing means is taken out by the second polarizing means, the image of the video display device can be visually recognized.

  On the other hand, when viewed from a direction other than the front direction (hereinafter referred to as viewed from an oblique direction), the visually recognized image is different in the single screen display mode or the multiple screen display mode.

  In the single screen display mode, the major axis direction of the liquid crystal molecules is substantially parallel or substantially perpendicular to the substrate, so the major axis direction of the liquid crystal molecules when projected from an oblique direction is the same as when viewed from the front. become. Therefore, even when viewed from an oblique direction, birefringence does not occur in the liquid crystal molecules, and incident light can pass through the liquid crystal layer and the second polarizing means, and the image of the video display device can be visually recognized.

  On the other hand, in the multi-screen display mode, the major axis direction of the liquid crystal molecules is inclined with respect to the substrate, so the major axis direction of the liquid crystal molecules when projected from an oblique direction is the crossing angle with the polarization direction of the incident light. It has. Therefore, when viewed from an oblique direction, birefringence occurs in the liquid crystal molecules, the polarization direction of the light transmitted through the liquid crystal layer changes, and it becomes impossible to pass through the second polarizing means, and the image of the video display device can be visually recognized. Disappear.

  Therefore, in the single screen display mode, the image displayed by the video display means can be viewed from any direction, and in the multiple image mode, the image displayed by the video display means can be viewed only from a specific direction. Therefore, with this display device, the viewing angle can be changed according to the situation such as when viewing a confidential document in a public place or when viewing a captured image with a large number of people.

  Further, according to such a configuration, since the viewing angle is controlled by controlling the birefringence, the display quality of the video display device can be kept good with a simple configuration.

  Even in the multi-screen display mode, there may be a region in the liquid crystal layer of the display switching means where the liquid crystal molecules exhibit the same orientation as in the single-screen display mode. In this case, when viewed from an oblique direction in the multi-screen display mode, the image of the video display device can be seen from the portion of the area.

  The “major axis direction” when liquid crystal molecules are projected assumes that all directions are the major axis direction when the projection is a perfect circle.

  In the display device of the present invention, the directions of the polarization transmission axes of the first polarization means and the second polarization means are the same, and the directions of the polarization transmission axes are perpendicular to the substrate of the display switching means. It is characterized by being substantially parallel or substantially perpendicular to the major axis direction of the liquid crystal molecules when projected.

  According to this, since the directions of the polarization transmission axes of the first polarizing means and the second polarizing means are the same, the second polarizing means emits straight lines from the liquid crystal molecules without using other members. Polarized light can be extracted. Therefore, the second polarization means can take out linearly polarized light emitted from the liquid crystal molecules with a simple structure.

  In the display device of the present invention, a polarization rotation member that rotates the polarization direction of light is further disposed between the first polarization means and the second polarization means. The polarization direction of the linearly polarized light incident on the liquid crystal molecules or the polarization direction of the linearly polarized light emitted from the liquid crystal molecules is rotated so that the linearly polarized light is extracted by the second polarizing means. It is characterized by.

  According to this, since the polarization rotating member rotates the polarization direction of the linearly polarized light emitted from the liquid crystal molecules so that the linearly polarized light is extracted by the second polarizing means, the first polarizing means and the first polarizing means Even if the polarization transmission axes of the two polarizing means do not coincide with each other, the second polarizing means can take out linearly polarized light emitted from the liquid crystal molecules. Therefore, the polarizing means for the liquid crystal display device can be used as the first polarizing means or the second polarizing means.

  The display device of the present invention is characterized in that the orientation direction of liquid crystal molecules changes in a region having a specific shape by switching between the single screen display mode and the multiple image display mode.

  According to this, when switching between the single screen display mode and the multiple image display mode, the orientation direction of the liquid crystal molecules changes only in a specific shape region, and in the region where the orientation direction does not change, regardless of the mode, Even when viewed from an oblique direction, the image of the video display device can be seen. Therefore, when viewed from an oblique direction in the multi-screen display mode, a specific shape such as a logo or a character can be displayed.

  In addition, the displayed logo and character are not reversed in black and white depending on the direction of the line of sight, and the same image is displayed from any angle. Therefore, the image of the liquid crystal display means is mostly displayed with a black image covered. Can be hidden.

  Further, in the display device of the present invention, a pattern electrode formed in a specific shape is disposed on at least one of the pair of substrates, and the alignment direction of the liquid crystal molecules in a region that receives a voltage applied to the pattern electrode Is characterized by changes.

  According to this, when the single screen display mode and the multiple image display mode are switched, only the liquid crystal molecules that have received the voltage applied to the pattern electrode change the alignment direction. Therefore, the region where the orientation direction changes corresponds to a specific shape of the pattern electrode. In the region where the orientation direction does not change, the image of the video display device can be seen even when viewed from an oblique direction regardless of the mode. Therefore, when viewed from an oblique direction in the multi-screen display mode, a specific shape corresponding to the pattern electrode can be visually recognized.

  For example, when switching to the multiple image display mode according to the application of the pattern electrode, by forming an electrode in which a character or logo is hollowed as the pattern electrode, when viewed from an oblique direction in the multiple screen display mode, An image with characters and logos appearing on the black image is visible.

  In addition, the display device of the present invention is characterized in that a single screen display mode is set when no voltage is applied to the liquid crystal molecules, and a multi-image display mode is set by applying a predetermined voltage to the liquid crystal molecules.

  Since it is easier to align liquid crystal molecules parallel or perpendicular to the substrate without applying voltage, it is preferable to set the single screen display mode without applying voltage. . Further, when the display is often used in the single screen display mode, the power consumption is lower in the single screen display mode when no voltage is applied.

  The display device of the present invention further includes video display means for displaying an image. In the single screen display mode, the image displayed by the video display means can be viewed from any direction, and in the multiple image display mode. From a specific direction, another image is visually recognized by overlapping with the image of the video display means by the birefringence of the display switching means.

  According to this, in the single screen display mode, the image displayed by the video display means can be viewed from any direction, and in the multiple image mode, the display image is hidden by overlapping the display image from the specific direction. A display device that can be used is realized.

  The “specific direction” is a direction other than the front direction described above.

  Further, in this configuration, in the multiple image mode, the major axis direction when at least some liquid crystal molecules of the image switching unit project from the direction orthogonal to the substrate and the polarization direction of the light transmitted through the first polarizing unit are This can be realized by controlling the alignment so that the major axis direction of the liquid crystal molecules is tilted with respect to the substrate.

  Further, the display device of the present invention further includes video display means for displaying an image, and in the multiple image display mode, the liquid crystal molecules are inclined in the vertical direction in the image displayed on the video display means. It is characterized by.

  Here, "the liquid crystal molecules are inclined in the vertical direction of the image displayed on the video display means" means that the image displayed on the video display means is upward or downward from a state perpendicular to the substrate. Means to tilt. In other words, the video display means and the display switching means are bonded so that the plane drawn by the dots on the liquid crystal molecules when the orientation changes and the vertical direction of the image displayed on the video display means are substantially parallel. ing.

  According to the above configuration, when the vertical direction of the image of the video display means is set to the vertical direction, the image of the video display means is seen from the front of the display device, and from the left and right, another image switching means is used by the image switching means. The image on which the images are superimposed is visually recognized. Therefore, an image can be hidden from more people in places where the line of sight is assumed to be relatively uniform, such as places where many people are standing.

  The display device of the present invention further includes video display means for displaying an image, the polarizing means is provided on both surfaces of the video display means, and the polarizing means is provided on one surface of the display switching means. The surface of the display switching means that is not provided with the polarizing means and the image display means are bonded together.

  According to this, since the polarizing means, the video display means, the polarizing means, the display switching means, and the polarizing means are arranged in this order, the image quality of the display device is improved.

  In addition, since the polarization means is provided only on one side of the display switching means, there is only one polarization means sandwiched between the video display means and the display switching means, which is advantageous in terms of cost and labor of the manufacturing process. Furthermore, by providing the polarizing means only on one side of the display switching means, it is possible to cope with cases where the polarizing means are already provided on both sides of the video display means, such as when a liquid crystal display device is used as the video display means.

  The display device of the present invention further includes video display means for displaying an image, and the video display means or the display switching means is provided with a polarization rotation member that rotates the polarization direction. Is rotated by rotating the polarization direction of the linearly polarized light incident on the first polarizing means, the linearly polarized light incident on the liquid crystal molecules, or the linearly polarized light emitted from the liquid crystal molecules. It is characterized by the linearly polarized light extracted by the means.

  According to this, linearly polarized light such that the polarization rotating member provided in the image display means or the display switching means rotates the polarization direction of the linearly polarized light emitted from the liquid crystal molecules and is extracted by the second polarizing means. Therefore, even if the polarization transmission axes of the first polarizing means and the second polarizing means do not coincide, the second polarizing means can take out linearly polarized light emitted from the liquid crystal molecules. Therefore, the polarizing means provided in the liquid crystal display means can be used as the first polarizing means or the second polarizing means.

  The display device of the present invention further includes video display means for displaying an image, and the luminance of the video display means is switched between the single screen display mode and the multiple image mode.

  According to this, by setting the brightness high in the single screen display mode and setting the brightness low in the multiple image mode, the effect of hiding the image of the video display means is further enhanced, and the power consumption of the video display means is reduced. There is an effect that it can be reduced.

  In addition, the display device of the present invention is characterized in that, in the multiple image display mode, an angle formed between the major axis direction of the liquid crystal molecules and the substrate is 40 degrees or more and 50 degrees or less.

  In the image switching means, the angle formed between the major axis direction of the liquid crystal molecules and the substrate is 45 degrees, so that the major axis direction of the liquid crystal molecules when projected from an oblique direction is 45 degrees with the polarization direction of the incident light. Has a crossing angle. At this time, when viewed from an oblique direction, optimal birefringence occurs in the liquid crystal molecules, the polarization direction of the light transmitted through the liquid crystal layer changes, and the light does not pass through the second polarizing means, so that the image of the video display device is optimally hidden. .

  Therefore, in the multi-image display mode, when the angle between the major axis direction of the liquid crystal molecules and the substrate is set to 40 degrees or more and 50 degrees or less, when viewed from a specific direction, other images are good as the display image. The display image can be hidden by overlapping, and the function of changing the viewing angle according to the situation is further improved. On the other hand, when the angle between the major axis direction of the liquid crystal molecules and the substrate is out of the above range, the birefringence effect becomes lower and the image may not be sufficiently hidden.

  The viewing angle control device of the present invention is a viewing angle control device that controls and outputs the viewing angle of incident light, and includes a liquid crystal element and linearly polarizing means provided on the liquid crystal element. The major axis direction of the liquid crystal molecules of the liquid crystal element is included in the plane formed by the direction of the transmission axis or absorption axis of the linearly polarizing means and the traveling direction of light, and the liquid crystal molecules are aligned in the traveling direction of light. On the other hand, it is characterized by being able to take a state of being substantially vertical or substantially parallel to the state of being inclined with respect to the light traveling direction.

  By attaching such a viewing angle control device to a display device that is generally used, a display device having the above-described function is obtained.

  The electronic apparatus of the present invention is equipped with the display device or the viewing angle control device as described above.

  Therefore, it is possible to realize an electronic device that can display with a simple configuration, display quality can be maintained, and display images can be hidden from a specific direction by mode switching.

  As described above, the display device according to the present invention is a liquid crystal layer in which the display switching unit is a liquid crystal layer disposed between a pair of substrates, and the liquid crystal molecules of the liquid crystal layer are projected from a direction orthogonal to the substrate. The major axis direction of the molecule and the polarization direction of the light incident on the liquid crystal molecule are always substantially parallel or substantially perpendicular, and the second polarizing means takes out the linearly polarized light emitted from the liquid crystal molecule. In the single-screen display mode, at least some of the liquid crystal molecules in the liquid crystal layer are aligned so that the major axis direction of the liquid crystal molecules is substantially parallel or substantially perpendicular to the substrate. The major axis direction is oriented so as to be inclined with respect to the substrate.

  The viewing angle control device of the present invention is a viewing angle control device that controls and outputs the viewing angle of incident light, and includes a liquid crystal element and a linearly polarizing plate provided on the liquid crystal element. The major axis direction of the liquid crystal molecules of the liquid crystal element is included in the plane formed by the transmission axis or absorption axis direction of the linear polarizing plate and the light traveling direction, and the liquid crystal molecules are aligned in the light traveling direction. On the other hand, it can be in a state of being substantially vertical or substantially parallel and a state of being inclined with respect to the traveling direction of light.

  The electronic apparatus of the present invention is equipped with such a display device or a viewing angle control device.

  According to this, not only the selected mode but also when the display device is viewed from the front, birefringence does not occur, and incident light passes through the liquid crystal layer and the second polarizing means, so that the image of the video display device is displayed. Visible. On the other hand, when the display device is viewed from a direction other than the front direction (for example, when viewed from diagonally forward), the image of the video display device can be visually recognized in the single screen display mode, but birefringence in the multiple screen display mode. As a result, the image on the video display device cannot be viewed.

  Therefore, in the single screen display mode, the image displayed by the video display means can be viewed from any direction, and in the multiple image mode, the image displayed by the video display means can be viewed only from a specific direction. Therefore, the display image can be hidden by overlapping the display image from the specific direction by switching the mode while maintaining the display quality.

  An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 2 shows the appearance of a mobile phone (electronic device) 1 according to an embodiment of the present invention. The mobile phone 1 according to the present embodiment is a so-called clamshell type, and is shown in an open state in FIG. FIG. 2 shows a portion that becomes an inner side when the cellular phone 1 is closed, and a side that is mainly used by a user when the cellular phone 1 is opened. Therefore, in the present application, the side shown in FIG.

  As shown in FIG. 2, the mobile phone 1 includes a main body 2 and a lid 3, and the main body 2 and the lid 3 are connected in a hinge shape. The lid 3 is provided with a display unit (display device) 4 on the front side.

  The main body 2 is provided with a main operation button group 6 on the front side. The main operation button group 6 includes a function button group 7 for performing various settings and function switching in the mobile phone 1 and an input button group 8 for inputting symbols such as numbers and letters. Specifically, the function button group 7 includes a power button for switching on / off the power of the mobile phone, a camera button for starting a shooting mode, a mail button for starting a mail mode, and moving a selection target in the vertical and horizontal directions. For example, and a determination button which is arranged at the center of the cross button and determines various selections. The input button group 8 is a numeric keypad.

  The cellular phone 1 according to the present invention is configured such that when a main image such as a mail text or a photographed image is displayed on the display unit 4, another image is visible on the display unit 4 from the surroundings. Hereinafter, the setting in which the e-mail body and the photographed image cannot be seen from the surroundings is referred to as a narrow viewing angle mode (multiple image display mode), and the mode in which the display unit 4 can be viewed from any angle as usual is wide viewing. It is called a corner mode (single screen display mode). The user can arbitrarily change the setting of the narrow viewing angle mode and the wide viewing angle mode using the operation buttons.

  As shown in FIG. 3, in the wide viewing angle mode, the display unit 4 is viewed from the front (front orientation), and is also viewed from an oblique front on the right side from the front toward the display unit 4 (right side surface). (Azimuth), the main image is also visually recognized when viewed from the front obliquely to the left from the front toward the display unit 4 (left side orientation). On the other hand, in the narrow viewing angle mode, as shown in FIG. 4, the main image is visually recognized in the front direction, but from the right side direction or the left side direction, the switching image including the “SHARP” logo on the black display is displayed. Overlapping is visible.

  Below, the detailed structure of this display part 4 is demonstrated.

  A cross-sectional view of the display unit 4 is shown in FIG. The display unit 4 includes a second polarizing plate (second polarizing unit, linear polarizing plate) 11, a switching liquid crystal display unit (display switching unit, liquid crystal element; hereinafter referred to as SW-LCD) 12, a first polarizing plate (first polarizing plate). 1 polarizing means) 13, a main liquid crystal display unit (image display means, hereinafter referred to as main LCD) 14, and a third polarizing plate 15 are laminated in this order, and a backlight 16 is provided on the third polarizing plate side. ing.

  Here, the relationship between the polarization transmission axis of the first polarizing plate 13 and the polarization transmission axis of the second polarizing plate 11 is preferably set in parallel, but according to the requirements of the characteristics of the main LCD, May have any axis angle.

  In this case, the polarization direction of the linearly polarized light emitted from the first polarizing plate 13 set at an arbitrary axis angle is appropriately adjusted to match the transmission axis of the second polarizing plate 11 with a λ / 2 plate or the like. By rotating, the same effect as when the polarization transmission axis of the first polarizing plate 13 and the polarization transmission axis of the second polarizing plate 11 are set in parallel can be obtained.

  The second polarizing plate 11 is attached to the SW-LCD 12, and the first polarizing plate 13 and the third polarizing plate 15 are attached to both surfaces of the main LCD 14, and the second polarizing plate of the SW-LCD 12. The side to which 11 is not attached and the main LCD are bonded by the bonding portion 17 via the first polarizing plate 13. And what adhered the 2nd polarizing plate 11 to SW-LCD12 functions as a viewing angle control apparatus. Further, the bonding portion 17 may be bonded with a thermosetting or ultraviolet curable resin adhesive, or may be fixed with a so-called double-sided tape. Further, the pasting area may be a whole surface bonding or a partial bonding such as a frame shape.

  In the main LCD 14, a liquid crystal layer 43 is sealed between the transparent electrode substrates 41 and 42. By applying a voltage to the transparent electrode substrates 41 and 42 according to a control unit (not shown), the alignment of liquid crystal molecules in the liquid crystal layer 43 is performed. Change the to display the image. The main LCD 14 is controlled by a control unit (not shown) so as to display an operation screen of the mobile phone 1, a picture, an image such as a mail text, and the like. As the main LCD 14, a generally known liquid crystal display device may be used. For example, a liquid crystal display device of any mode such as a TN (Twisted Nematic) mode liquid crystal display device driven by an active matrix drive method or a VA (Vertical alignment) mode display type liquid crystal display device can be used. Further, instead of the main liquid crystal display unit 14, a self-luminous display such as an organic EL (Electroluminescence) display device or a plasma display device may be used. In the case of a self-luminous type, a backlight is not necessary.

  In the SW-LCD 12, a substrate 21, a transparent electrode film 26, an alignment film 24, a liquid crystal layer 23, an alignment film 25, a transparent electrode film 27, and a substrate 22 are formed in this order. The initial alignment direction of the liquid crystal molecules of the liquid crystal layer 23 is determined according to the alignment films 25 and 27, and the alignment direction is changed by voltage application from a control unit (not shown) to the transparent electrodes 26 and 27. Then, the narrow viewing angle mode and the wide viewing angle mode are switched by the change in the orientation direction.

  A liquid crystal layer 23 is disposed between the substrates 21 and 22. By applying a voltage to the transparent electrode films 26 and 27 according to a control unit (not shown), the orientation of the liquid crystal molecules in the liquid crystal layer 23 is changed, thereby Is displayed. The control unit changes the alignment direction of the liquid crystal molecules of the liquid crystal layer 23 to the alignment direction for the wide viewing angle mode or the narrow viewing angle mode according to the wide viewing angle mode or the narrow viewing angle mode set by the user. . Only one of the alignment films 24 and 25 may be provided.

  The backlight 16 supplies light for display. The third polarizing plate 15 extracts linearly polarized light in a certain direction from the light of the backlight 16 before entering the main LCD 14. The first polarizing plate 13 extracts linearly polarized light in a certain direction from the light before passing through the main LCD 14 and entering the SW-LCD 12. The second polarizing plate 11 extracts linearly polarized light in a certain direction from the backlight light transmitted through the main LCD 14 and the SW-LCD 12.

  Hereinafter, examples of alignment of liquid crystal molecules in four SW-LCDs will be described with reference to FIGS.

(SW-LCD liquid crystal molecular alignment example 1)
FIG. 5A shows the display surface of the display unit 4 of the mobile phone 1 so that the vertical direction of the image of the main-LCD 14 is the vertical direction of the paper. Hereinafter, the horizontal direction on the display screen is referred to as the x direction, the vertical direction is referred to as the y direction, and the thickness direction of the display unit 4 is referred to as the z direction. In FIGS. 5 to 10, the transparent electrode films 26 and 27 and the alignment films 24 and 25 are not shown.

  First, as shown in FIG. 5A, the polarization transmission axes of the second polarizing plate 11 and the first polarizing plate 13 are arranged in the y direction. In addition, the rubbing direction of the alignment films 24 and 25 is made parallel to the polarization transmission axes of the first and second polarizing plates 11 and 13 and opposite to each other by 180 degrees, so that the alignment direction has an anti-parallel structure. Then, a polyimide material of a horizontal alignment material is used as the alignment films 24 and 25, and liquid crystal molecules are aligned so as to be substantially parallel to the substrates 21 and 22. Thus, the liquid crystal molecules are uniaxially aligned so that the major axis direction of the liquid crystal molecules is substantially parallel to the polarization transmission axis.

  In this case, as shown in the AA ′ cross-sectional view of FIG. 5B, the liquid crystal molecules of the SW-LCD 12 are uniaxially aligned substantially parallel to the polarization transmission axis of the first polarizing plate 13 in the absence of voltage application. Yes. Light incident on the SW-LCD 12 from the backlight 16 via the main LCD 14 is transmitted through the first polarizing plate 13, so that the polarization direction of the light incident on the SW-LCD 12 and the alignment direction “a” of the liquid crystal molecules are substantially the same. .

  FIG. 5C shows how the liquid crystal molecules are seen when the SW-LCD 12 in this state is viewed while being displaced in the x direction. According to the figure, the shape when the liquid crystal molecules are projected from the front direction (the shape of the liquid crystal molecules as viewed from the observer 31) is the liquid crystal molecules 35a, and the major axis direction and the deflection direction of the incident light substantially coincide. ing. When the angle formed between the major axis direction of the projection diagram of the liquid crystal molecules and the polarization direction of the incident light is 0 degree, the incident light is transmitted without being influenced by birefringence. In this case, the image of the main LCD 14 is directly used. Can be seen. Similarly, the shape of the liquid crystal molecules projected from the viewpoint shifted in the x direction from the front (the shape of the liquid crystal molecules as viewed from the observers 32 and 33) is also the liquid crystal molecules 35b and 35c, and is incident on the major axis direction. The light deflection directions are substantially the same. Therefore, the image on the main LCD 14 can be seen. That is, the image on the main LCD 14 can be seen from any direction. This state, that is, the state in which no voltage is applied, is set as the wide viewing angle mode.

  On the other hand, in the narrow viewing angle mode, an AC voltage (on the transparent electrode films 25 and 26 is applied so that the liquid crystal molecules are inclined 45 degrees with respect to the substrates 21 and 22 by rotation about the x direction from the state where no voltage is applied. For example, a voltage of 100 Hz and 3 V) is applied. The state of the liquid crystal molecules at this time is shown in FIGS. FIG. 7A shows the A-A ′ cross section, and it can be seen that the substrate is inclined 45 degrees with respect to the substrates 21 and 22. FIG. 7B shows the B-B ′ cross section, in which the liquid crystal molecules are inclined by about 45 degrees from the normal direction to the paper surface.

  In this case, as shown in FIG. 7B, the liquid crystal molecules viewed from the observer 31, that is, the projection view of the liquid crystal molecules from the front direction, is the liquid crystal molecules 36a. Since the orientation change of the liquid crystal molecules is caused by rotation about the x-axis direction, the polarization directions of the second polarizing plate 11 and the first polarizing plate 13 always coincide with the major axis direction of the liquid crystal molecules 36a. For this reason, when viewed from the front direction (when viewed by the observer 31 in FIG. 7), the image of the main LCD 14 can be seen as it is without being affected by birefringence.

  On the other hand, a liquid crystal molecule viewed from the viewer 32 on the left side toward the display unit 4, that is, a projection diagram of the liquid crystal molecule projected from the left side toward the substrates 21 and 22 is a liquid crystal molecule 36b. In this case, since the polarization direction of the second polarizing plate 11 and the first polarizing plate 13 has an angle with the major axis direction of the liquid crystal molecule projection diagram (liquid crystal molecule 36b), the major axis direction of the liquid crystal molecule projection diagram is incident light. The polarization direction and the crossing angle. Therefore, when viewed from the observer 32, the light is not transmitted through the SW-LCD 12 due to the influence of the birefringence of the liquid crystal, and the image of the main LCD 12 cannot be seen.

  Similarly, a liquid crystal molecule viewed from the observer 33 on the right side toward the display unit 4, that is, a projection diagram of the liquid crystal molecule from the right side toward the substrates 21 and 22 is a liquid crystal molecule 36c. Since the polarization direction of the second polarizing plate 11 and the first polarizing plate 13 has an angle with the major axis direction of the projection diagram, the major axis direction of the liquid crystal molecule projection diagram has a crossing angle with the polarization direction of the incident light, and is polarized. The direction rotates. Therefore, when viewed from the observer 33, the light is not transmitted through the SW-LCD 14 due to the influence of the birefringence of the liquid crystal, and the image of the main LCD 12 cannot be seen.

  When a voltage is applied to the transparent electrode films 26 and 27 by the above-described mechanism, as shown in FIG. 4, when the display unit 4 is viewed from the front direction (when viewed by the observer 31), birefringence occurs. The image of the main LCD 14 can be seen as it is without being influenced by the light, but when viewed from the direction other than the front direction (when viewed by the observers 32 and 33), the light is not transmitted through the SW-LCD due to the influence of birefringence. The image on the main LCD 14 becomes invisible.

  In addition, the orientation direction of the liquid crystal molecules in the narrow viewing angle mode is not limited to 45 degrees with respect to the substrates 21 and 22, and any angle can be used as long as it is inclined with respect to the substrates 21 and 22. But it doesn't matter. In other words, it may be larger than the inclination angle when substantially parallel to the substrates 21 and 22 and smaller than the inclination angle when substantially vertical (that is, if it is larger than 0 degrees and smaller than 90 degrees). The inclination angle is preferably 10 degrees or more and 80 degrees or less, and more preferably 40 degrees or more and 50 degrees or less. This is because the birefringence increases as the inclination angle approaches 45 degrees, and the image can be favorably hidden. Further, when the tilt angle is small, the driving voltage is small, so that power consumption can be reduced.

  Note that when the observer is displaced in the y direction, the major axis direction of the projection diagram of the liquid crystal molecules does not change, so whether or not the main LCD 12 is visible depends only on the displacement of the viewpoint in the x direction. Therefore, a line of sight from a direction parallel to the yz plane (a plane drawn by rotation of a point on the liquid crystal molecule that changes the alignment direction) is taken as a line of sight from the front direction.

  Further, for one of the transparent electrode films 26 and 27 (FIG. 6 (a)) or both (FIG. 6 (b)), an electrode is arranged on a portion other than the logo portion indicated by white of “SHARP” (black portion). Thus, the electrode patterning is used. Thus, at least in the logo portion where no voltage is applied to one of the transparent electrode films, no voltage is applied to the liquid crystal molecules, so that the alignment direction is substantially parallel to the substrates 21 and 22 as in the case where no voltage is applied. Therefore, only the logo portion is not affected by birefringence in the SW-LCD 14 when viewed from any direction. Therefore, the image seen by the viewers 32 and 33 is a logo image like the display unit 4 in FIG. 6 in which light is blocked except for the logo portion and light is transmitted through the logo portion.

  For the purpose of hiding the image of the main LCD 14, the pattern electrode preferably covers 60% or more, preferably 80% or more of the display unit 4 with the electrode. However, for the purpose of simply making the image of the SW-LCD 12 overlap the image of the main LCD 14, the pattern electrodes may be arranged by any electrode distribution.

(SW-LCD liquid crystal molecular alignment example 2)
A liquid crystal molecule alignment example 2 of the SW-LCD will be described with reference to FIG. Liquid crystal molecule alignment example 2 is realized by using SW-LCD 12 ′ using an alignment film using a polyimide material of a vertical alignment material instead of alignment films 24 and 25 in SW-LCD 12. As a result, as shown in FIG. 8A, the liquid crystal molecules are aligned so as to be substantially perpendicular to the electrode substrates 21 and 22.

  In this case, the liquid crystal molecules of the SW-LCD 12 ′ are uniaxially aligned substantially perpendicular to the substrates 21 and 22 in the state where no voltage is applied. That is, when viewed from the front, the liquid crystal molecules 37a appear to be a perfect circle (when the projection diagram is a perfect circle, all directions are considered to be major axis directions). And when it sees from directions other than the front, a major axis direction turns into x direction like liquid crystal molecule 37b * 37c. Therefore, in the case of projecting from any direction including the front direction, the major axis direction b and the incident light deflection direction are 90 degrees. When the angle between the major axis direction of the liquid crystal molecule projection and the polarization direction of the incident light is 90 degrees (right angle), the incident light is transmitted without being affected by birefringence. However, the image of the main LCD 14 can be seen as it is. This state, that is, the state in which no voltage is applied, is set as the wide viewing angle mode.

  On the other hand, in the narrow viewing angle mode, the AC voltage is applied to the transparent electrode films 26 and 27 so that the liquid crystal molecules are inclined 45 degrees with respect to the substrates 21 and 22 by the rotation about the x direction from the state of the wide viewing angle mode. multiply. The state of the liquid crystal molecules at this time is the same as in the case of the alignment example 1 of the SW-LCD shown in FIG.

  Therefore, when a voltage is applied to the transparent electrode films 26 and 27 by the same mechanism, as shown in FIG. 3, the display unit 4 is birefringent when viewed from the front (when viewed by the observer 31). The image of the main LCD 14 can be seen as it is without being influenced by the image, but when viewed from the direction other than the front direction (when viewed by the observers 32 and 33), the logo image is seen due to the effect of birefringence.

(SW-LCD liquid crystal molecular alignment example 3)
FIG. 9A shows the display unit 4 of the mobile phone 1 so that the vertical direction of the display screen is the vertical direction of the page.

  First, as shown in FIG. 9A, the polarization transmission axes of the first polarizing plate 13 and the second polarizing plate 11 are arranged in the x direction. Then, the rubbing direction of the alignment films 24 and 25 is perpendicular to the polarization transmission axes of the first polarizing plate 13 and the second polarizing plate 11 (y direction) and opposite to each other by 180 degrees, and the alignment direction is antiparallel. Make the structure. Then, a polyimide material of a horizontal alignment material is used as the alignment films 24 and 25, and liquid crystal molecules are aligned so as to be substantially parallel to the substrates 21 and 22. Thus, as shown in FIG. 9B, the liquid crystal molecules are uniaxially aligned so that the major axis direction of the liquid crystal molecules is substantially perpendicular to the polarization transmission axis of the polarizing plate.

  In this case, as shown in FIG. 9B, the liquid crystal molecules of the SW-LCD 12 are parallel to the substrates 21 and 22 and are perpendicular to the polarization transmission axis of the first polarizing plate 13 when no voltage is applied. Is uniaxially oriented. The light incident from the backlight 16 through the main LCD 14 is transmitted through the first polarizing plate 13, so that the polarization direction of the light incident on the SW-LCD 12 and the alignment direction of the liquid crystal molecules are perpendicular. FIG. 9C shows how the liquid crystal molecules appear when the SW-LCD 12 in this state is viewed while being shifted in the x direction. According to the figure, the shape when projected from the front direction (the shape of the liquid crystal molecules viewed from the observer 31) is the liquid crystal molecules 38a, and the major axis direction c of the projected liquid crystal molecules and the deflection direction of the incident light. Becomes a right angle. When the angle between the major axis direction of the liquid crystal molecule projection and the polarization direction of the incident light is 90 degrees, the incident light is transmitted without being influenced by birefringence. The image on the main LCD 14 can be seen as it is. This state, that is, the state in which no voltage is applied, is set as the wide viewing angle mode.

  On the other hand, in the narrow viewing angle mode, an AC voltage is applied to the transparent electrode films 25 and 26 so that the liquid crystal molecules are inclined 45 degrees with respect to the substrates 21 and 22 by rotation about the x direction from the state where no voltage is applied. Call. The state of the liquid crystal molecules at this time is shown in FIG. FIG. 10A shows an A-A ′ cross section, and it can be seen that the substrate is inclined at 45 degrees with respect to the substrates 21 and 22. FIG. 10B shows a B-B ′ cross section, in which the liquid crystal molecules are inclined 45 degrees from the normal direction to the paper surface.

  In this case, as shown in FIG. 10B, a liquid crystal molecule viewed from the observer 31, that is, a projection view of the liquid crystal molecule from the front direction, is a liquid crystal molecule 39a. Since the change in the alignment direction of the liquid crystal molecules is due to rotation about the x direction, the polarization direction of the second polarizing plate 11 and the first polarizing plate 13 is perpendicular to the major axis direction of the liquid crystal molecules 39a. Therefore, the projection view of the liquid crystal molecules, the major axis direction, and the polarization direction of the incident light are substantially perpendicular. Therefore, when viewed from the front direction (when viewed by the observer 31), the image on the main LCD 14 can be seen as it is without being affected by birefringence.

  On the other hand, the liquid crystal molecules viewed from the viewer 32 on the left side toward the display unit 4, that is, the projections of the liquid crystal molecules from the left side toward the substrates 21 and 22 become liquid crystal molecules 39b. Since the polarization directions of the second polarizing plate 11 and the first polarizing plate 13 have an angle with the major axis direction of the projection diagram, the major axis direction of the liquid crystal molecule projection diagram has an intersection angle with the polarization direction of the incident light. Therefore, when viewed from the observer 32, the light is not transmitted through the SW-LCD 12 due to the influence of the birefringence of the liquid crystal, and the image of the main LCD 12 cannot be seen.

  Similarly, a liquid crystal molecule viewed from the viewer 33 on the right side toward the display unit 4, that is, a projection diagram of the liquid crystal molecule from the right side toward the substrates 21 and 22 is a liquid crystal molecule 39c. Since the polarization directions of the first polarizing plate 13 and the second polarizing plate 11 have an angle with the major axis direction of the projection diagram, the major axis direction of the liquid crystal molecule projection diagram has an intersection angle with the polarization direction of the incident light. Therefore, when viewed from the observer 33, light does not pass through the SW-LCD 12 due to the influence of the birefringence of the liquid crystal, and the image of the main LCD 12 cannot be seen.

  When a voltage is applied to the transparent electrode base films 26 and 27 by the above-described mechanism, as shown in FIG. 4, when the display unit 4 is viewed from the front direction (when viewed by the observer 31), a plurality of images are displayed. Although the image of the main LCD 14 can be seen as it is without being influenced by refraction, when viewed from other than the front direction (when viewed by the observers 32 and 33), light is transmitted through the SW-LCD 12 due to the influence of birefringence. Therefore, the image on the main LCD 14 becomes invisible.

(Liquid crystal molecular alignment example 4 of SW-LCD)
A liquid crystal molecule alignment example 4 of the SW-LCD will be described with reference to FIG. The alignment example 4 is realized by using the SW-LCD 12 ′ using an alignment film using a polyimide material of a vertical alignment material instead of the alignment films 24 and 25 in the alignment example 3 of the SW-LCD. Thereby, the liquid crystal molecules can be aligned so as to be substantially perpendicular to the substrates 21 and 22.

  In this case, the liquid crystal molecules of the SW-LCD 12 ′ are uniaxially aligned substantially perpendicular to the substrates 21 and 22 in the state where no voltage is applied. That is, as shown in FIG. 11B, when viewed from the front, it looks like a perfect circle of the liquid crystal molecules 40a. When viewed from a direction other than the front, the major axis direction appears to be the x direction as in the liquid crystal molecules 40b and 40c. Therefore, even when liquid crystal molecules are projected from any direction including the direction orthogonal to the substrate, the major axis direction and the deflection direction of the incident light coincide. When the angle between the major axis direction of the liquid crystal molecule projection and the polarization direction of the incident light is 0 degree (parallel), the incident light is transmitted without being affected by birefringence. However, the image of the main LCD 14 can be seen as it is. This state, that is, the state in which no voltage is applied, is set as the wide viewing angle mode.

  On the other hand, in the narrow viewing angle mode, the AC voltage is applied to the transparent electrode films 26 and 27 so that the liquid crystal molecules are inclined 45 degrees with respect to the substrates 21 and 22 by the rotation about the x direction from the state of the wide viewing angle mode. multiply. The state of the liquid crystal molecules at this time is the same as that of SW-LCD alignment method 1 shown in FIG.

  Therefore, when a voltage is applied to the transparent electrode films 26 and 27 by the same mechanism, as shown in FIG. 4, the display unit 4 is birefringent when viewed from the front direction (when viewed by the observer 31). The image of the main LCD 14 can be seen as it is without being influenced by the image, but when viewed from the direction other than the front direction (when viewed by the observers 32 and 33), the logo image is seen due to the effect of birefringence.

(Transmission measurement experiment)
Using the SW-LCDs of liquid crystal molecule alignment examples 1 and 3, the change in transmittance according to the line-of-sight direction in the multiple image display mode was measured. The results are shown in FIGS.

  FIG. 12 is a graph showing measurement results when the SW-LCD of the liquid crystal molecule alignment example 1 is set to the multiple image display mode. In the measurement, the polarizing transmission axis of the first polarizing plate is arranged in the vertical direction, and the target point is not changed from the line of sight (elevation angle 0 degree) perpendicular to the display unit 4 (normal direction). The viewpoint was shifted left and right. The viewpoint is shifted from an elevation angle of 0 degrees until the angle between the direction perpendicular to the display unit 4 and the line of sight reaches 80 degrees (until the elevation angle reaches 80 degrees), and the viewpoint is viewed from the line of sight and the line of sight. The transmittance of the SW-LCD was measured. The horizontal axis of the graph indicates the elevation angle, and the vertical axis indicates the transmittance. Moreover, as SW-LCD, it measured using the thing of retardation when it sees from the front 500nm, 600nm, 800nm, 1000nm, 1500nm.

  According to this, all showed the maximum transmittance of about 85% at an elevation angle of 0 degree, and the transmittance decreased as the elevation angle increased. In the case of the retardation of 1500 nm, the transmittance was almost 0% at an elevation angle of about 30 degrees, and the transmittance rose again when the elevation angle was further increased. When the retardation is 1000 nm, the elevation angle is about 38 degrees, and when the retardation is 800 nm, the elevation angle is about 44 degrees and the transmittance is almost 0%. Further, when the retardation is 600 nm and 500 nm, the minimum is at an elevation angle of about 50 degrees and about 60 degrees, respectively, and the transmittance is kept below 10% even if the elevation angle is increased thereafter.

  For SW-LCD, the retardation is determined according to the direction in which the main LCD is not desired to be visually recognized, or in accordance with the use environment, the luminance of the main LCD, etc. do it. For example, when hiding the image of the main LCD with respect to a line of sight from an elevation angle of about 45 degrees, a SW-LCD having a low transmittance at this elevation angle and showing retardation of 500 nm to 1000 nm may be used. When it is desired to hide the image of the main LCD around the line of sight from an elevation angle of 30 ° to 50 °, a retardation having a low transmittance in this range and having a retardation of 800 nm to 1000 nm may be used. On the other hand, when it is desired to hide the image of the main LCD with respect to the line of sight from a range where the elevation angle is greater than 40 degrees, it is sufficient to use a retardation having a retardation of 500 nm to 600 nm in this range.

  Similarly, FIG. 13 is a graph showing the measurement results when the SW-LCD of the liquid crystal molecule alignment example 3 is set to the multiple image display mode. Compared with FIG. 12, the transmittance when the elevation angle is large is higher, and therefore, as in liquid crystal molecule alignment example 1, it is more preferable that the major axis direction of the liquid crystal molecules is substantially parallel to the polarization transmission axis. Since the characteristic of the curve is similar to that of FIG. 12, the optimum retardation may be selected in the same manner.

  In the above description, the SW-LCD 12 is located on the front surface (display surface side) of the main LCD 14 as an example. However, like the display unit 44 in FIG. 14, the SW-LCD 12 is on the back surface (opposite the display surface) of the main LCD 14. However, since the incidence of light on the main LCD 14 can be controlled, the viewing angle can be controlled. In the display unit 44, the polarizing plates 11 and 17 are arranged on both surfaces of the main LCD 14, and the polarizing plate 13 is arranged on the outer surface of the SW-LCD 12.

  However, when the SW-LCD 12 is in front of the main LCD 14, the outline of the image superimposed by the SW-LCD 12 appears clearly. In the multi-image display mode, when the main LCD 14 performs transmissive liquid crystal display, the SW-LCD 12 may be on the front surface or the rear surface. However, when performing the reflective liquid crystal display, incident light is incident. Since it reflects without passing through the main LCD 14, the SW-LCD 12 must be disposed on the front surface of the main LCD 14.

  On the other hand, when the SW-LCD 12 is behind the main LCD 14, the light is not attenuated by the SW-LCD 12 when the main LCD 14 displays a reflective liquid crystal display. Therefore, it is preferable that the SW-LCD 12 is disposed on the back surface of the main LCD 14 in the case of a transflective liquid crystal display device or a reflective liquid crystal display in a single image display mode.

  Further, the display device of the present invention is configured to be in a single image display mode with no voltage applied to the transparent electrode film, and to be in a multiple image display mode by applying a predetermined voltage to the transparent electrode film. The multi-image display mode may be set when no voltage is applied, and a single image display mode may be set by applying a predetermined voltage to the transparent electrode film. This configuration is realized by pre-tilting the liquid crystal molecules, for example, at 45 degrees with respect to the substrate, and controlling the alignment so that the liquid crystal molecules are substantially perpendicular or substantially parallel to the substrate by applying a voltage. According to such a configuration, power consumption can be reduced when the narrow viewing angle is often set in the multiple image display mode.

  The SW-LCD 12 is provided with a pattern electrode in which a logo portion is hollowed out. In the multiple image mode, the orientation of liquid crystal molecules is changed at a position corresponding to the pattern electrode. It may be driven. For example, the orientation of liquid crystal molecules corresponding to each pixel on the SW-LCD 12 may be controlled by switching a TFT (Thin Film Transistor) provided in the pixel. In this case, since the video signal is supplied to the SW-LCD 12 and the orientation of the liquid crystal molecules can be changed in the region corresponding to the video signal, an arbitrary image or moving image can be put on the image of the main LCD 14. .

  Furthermore, the display device of the present embodiment controls the viewing angle so that the image is not seen obliquely (from the left or right from the front) when facing the image on the main LCD 14, but the present invention is not limited to this. Alternatively, the viewing angle may be controlled so that the image cannot be seen obliquely from above or obliquely below.

  In order to realize this configuration, the image display means and the display switching means are arranged so that the horizontal direction of the image displayed on the image display means is substantially parallel to the plane drawn by the dots on the liquid crystal molecules when the orientation changes. Can be pasted together.

  In the display device of the present embodiment, the first polarizing plate 13 and the second polarizing plate 11 have the same polarization transmission axis, but the polarization transmission axes have an axial angle. Even in this case, as shown in FIG. 15, if a polarization rotation member 50 that rotates the polarization direction of incident light is disposed between the second polarizing plate 11 and the substrate 21, the same function can be provided. That is, the polarization rotating member 50 rotates the polarization direction of the linearly polarized light emitted from the liquid crystal molecules so that the linearly polarized light is extracted by the second polarizing plate 11, so that the first polarizing plate 13 and the second polarizing plate Even if the polarization transmission axes of the polarizing plate 11 do not coincide with each other, the linearly polarized light emitted from the liquid crystal molecules can be taken out by the second polarizing plate 11. As the polarization rotation member 50, a ½λ plate (retardation plate) can be used.

  Note that the polarization rotation member 50 may be disposed on the light incident side or the light emission side from the liquid crystal layer as long as it is between the first polarizing plate 13 and the second polarizing plate 11. Further, the polarization rotation member 50 may be installed on the light incident side from the first polarizing plate 13.

  In this embodiment, the case where the present invention is applied to a liquid crystal display unit of a mobile phone is described. However, the present invention is not limited to this, and a display device such as a mobile personal computer, an AV device, or a DVD player is used. Applicable to portable electronic devices. Alternatively, it may be applied to a non-portable display device and used as a display that can display differently depending on the viewing direction.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining the disclosed technical means are also applicable. It is included in the technical scope of the present invention.

  In addition, the present invention can be configured as follows.

  A normal display mode for displaying a single image in all azimuths of the viewing angle unique to the video display device on the front or back of the video display device for displaying a normal image, and the front orientation and the side orientation of the video display device; A multi-image display device comprising an optical element having a function of electrically switching between a multi-image display mode for displaying different images.

  In the multi-image display mode, a multi-image display device that displays an image of the video display device when displaying in the front direction and an image of the optical element as an image toward the side surface.

  A multi-image display device that displays the same image in both left and right side orientations in a multi-image display mode.

  The SW optical element for electrically switching between normal and multi-image display modes is composed of a pair of transparent electrode substrates and a liquid crystal layer in the gap between them, and characters or characters are displayed on the transparent electrodes in the lateral direction. The pattern for forming is formed.

  In the normal display mode, the alignment direction of the liquid crystal of the optical element is uniaxially aligned in a direction parallel or perpendicular to the transparent electrode substrate surface of the optical element, and in the multi-image display mode, it is uniaxially inclined obliquely with respect to the transparent electrode substrate. It is characterized by electrically switching between oblique orientation.

  The orientation direction is a vertical direction on a display display plane.

  A polarizing plate is disposed only on the substrate disposed on the opposite side of the pair of transparent electrode substrates of the SW optical element disposed on the front surface or the rear surface of the image display device from the image display device.

  The luminance of the video display device can be arbitrarily set in the normal display mode and the multiple image display mode.

  Since the display device of the present invention can be set to a mode in which different images are visually recognized depending on the direction of the line of sight, the display of a portable electronic device such as a mobile communication terminal, a mobile personal computer, an AV device, a DVD player, or the line of sight It can be applied to a display or the like that can present a plurality of information depending on the direction.

It is a figure which shows sectional drawing of the display part of the mobile telephone which concerns on embodiment of this invention. It is a figure which shows the mobile telephone which concerns on embodiment of this invention. 6 is a diagram showing a display unit viewed from the front or oblique direction when the mobile phone according to the embodiment of the present invention is set to the single image display mode. It is drawing which shows the display part 4 visually recognized from the front or diagonal direction, when the mobile telephone which concerns on embodiment of this invention is set to multiple image display mode. The display part when the mobile telephone which concerns on embodiment of this invention is set to single image display mode is shown, (a) is drawing which looked at the display surface of the display part, (b) is A-. A sectional view showing an A 'section, and (c) is a sectional view showing a BB' section. 1 is a view showing a transparent electrode film disposed in a display unit according to an embodiment of the present invention. The display part when the mobile telephone which concerns on embodiment of this invention is set to the multiple image display mode is shown, (a) is sectional drawing which shows an AA 'cross section, (b) is a BB' cross section. FIG. The display part when the mobile telephone which concerns on other embodiment of this invention is set to single image display mode is shown, (a) is sectional drawing which shows an AA 'cross section, (b) is B- It is sectional drawing which shows a B 'cross section. The display part when the mobile telephone which concerns on other embodiment of this invention is set to the single image display mode is shown, (a) is drawing which looked toward the display surface of the display part, (b) A sectional view showing an AA 'section, and (c) is a sectional view showing a BB' section. The display part when the mobile telephone which concerns on other embodiment of this invention is set to the multiple image display mode is shown, (a) is sectional drawing which shows an AA 'cross section, (b) is BB. It is a sectional view showing a section. The display part when the mobile telephone which concerns on other embodiment of this invention is set to single image display mode is shown, (a) is sectional drawing which shows an AA 'cross section, (b) is B- It is sectional drawing which shows a B 'cross section. 6 is a diagram illustrating a relationship between an elevation angle of line of sight and transmittance in the SW-LCD according to the embodiment of the present invention. 6 is a diagram illustrating a relationship between an elevation angle of line of sight and transmittance in a SW-LCD according to another embodiment of the present invention. It is a figure which shows sectional drawing of the display part of the mobile telephone which concerns on other embodiment of this invention. It is a figure which shows sectional drawing of the display part of the mobile telephone which concerns on embodiment of this invention.

Explanation of symbols

1 Mobile phone (electronic equipment)
4. Display unit (display device)
11 Second polarizing plate (second polarizing means)
12 Main liquid crystal display (video display means)
13 First polarizing plate (first polarizing means)
14 switch liquid crystal display (display switching means, liquid crystal element)
21 Substrate 22 Substrate 23 Liquid crystal layer 44 Display unit (display device)
50 Polarization rotating member

Claims (15)

Display switching means for electrically switching a visually recognized image between a single image display mode and a multiple image display mode;
First polarizing means for causing linearly polarized light in a certain direction to enter the display switching means;
A display device comprising: a second polarization unit that extracts linearly polarized light in a certain direction from the light emitted from the display switching unit;
The display switching means is a liquid crystal layer disposed between a pair of substrates;
When the liquid crystal molecules of the liquid crystal layer are projected from a direction orthogonal to the substrate, the major axis direction of the liquid crystal molecules and the linear polarization direction of light incident on the liquid crystal molecules are always substantially parallel or substantially perpendicular,
The second polarizing means takes out linearly polarized light emitted from the liquid crystal molecules;
At least some liquid crystal molecules of the liquid crystal layer are
In the single image display mode, the long axis direction of the liquid crystal molecules is aligned so as to be substantially parallel or substantially perpendicular to the substrate,
In the multi-image display mode, the display device is characterized in that the major axis direction is oriented so as to be inclined with respect to the substrate. The directions of the polarization transmission axes of the first polarizing means and the second polarizing means are the same,
2. The display device according to claim 1, wherein a direction of the polarization transmission axis is substantially parallel or substantially perpendicular to a major axis direction of liquid crystal molecules when projected from a direction orthogonal to the substrate of the display switching unit. . Furthermore, a polarization rotating member that rotates the polarization direction of light is disposed between the first polarizing means and the second polarizing means,
Linearly polarized light such that the polarization rotation member rotates the polarization direction of linearly polarized light incident on the liquid crystal molecules or the polarization direction of linearly polarized light emitted from the liquid crystal molecules and is extracted by the second polarizing means. The display device according to claim 1, wherein:   4. The display device according to claim 1, wherein the orientation direction of the liquid crystal molecules is changed in a region having a specific shape by switching between the single screen display mode and the multiple image display mode. 5. . A pattern electrode formed in a specific shape is disposed on at least one of the pair of substrates,
The display device according to claim 4, wherein the alignment direction of the liquid crystal molecules changes in a region that receives a voltage applied to the pattern electrode. Single image display mode when no voltage is applied to the liquid crystal molecules,
The display device according to claim 1, wherein a plurality of image display modes are set by applying a predetermined voltage to the liquid crystal molecules. Furthermore, it has a video display means for displaying an image,
In the single image display mode, the image displayed by the video display means can be viewed from any direction,
7. The multi-image display mode according to claim 1, wherein, from a specific direction, another image is visually recognized by overlapping with the image of the video display means due to the birefringence of the display switching means. Display device. Furthermore, it has a video display means for displaying an image,
8. The display device according to claim 1, wherein in the multiple image display mode, the liquid crystal molecules are inclined in the vertical direction in an image displayed on the video display means. 9. Furthermore, it has a video display means for displaying an image,
Polarizing means are provided on both surfaces of the image display means,
Polarizing means is provided on one surface of the display switching means,
The display device according to any one of claims 1 to 8, wherein a surface of the display switching means on which the polarizing means is not provided and the image display means are bonded together. Furthermore, it has a video display means for displaying an image,
The image display means or the display switching means is provided with a polarization rotation member that rotates the polarization direction,
The polarization rotating member rotates the polarization direction of linearly polarized light incident on the first polarizing means, linearly polarized light incident on the liquid crystal molecules, or linearly polarized light emitted from the liquid crystal molecules, 10. The display device according to claim 9, wherein the display device is linearly polarized light extracted by the second polarizing means. Furthermore, it has a video display means for displaying an image,
The display device according to any one of claims 1 to 10, wherein the luminance of the video display means is switched between a single image display mode and a multiple image display mode.   12. The display device according to claim 1, wherein an angle formed between a major axis direction of liquid crystal molecules and the substrate is 40 degrees or more and 50 degrees or less in the multiple image display mode. A viewing angle control device that controls and outputs the viewing angle of incident light,
A liquid crystal element;
A linearly polarizing plate provided on the liquid crystal element,
The major axis direction of the liquid crystal molecules of the liquid crystal element is included in a plane formed by the direction of the transmission axis or absorption axis of the linear polarizing plate and the traveling direction of light,
The viewing angle control device according to claim 1, wherein the liquid crystal molecules can take a state of being substantially perpendicular or substantially parallel to a light traveling direction and a state of being inclined with respect to the light traveling direction.   An electronic apparatus comprising the display device according to any one of claims 1 to 12.   An electronic apparatus comprising the viewing angle control device according to claim 13.

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