JP2009192961A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve display visibility in reflection display by incorporating a reflective polarizing plate to a liquid crystal display device. <P>SOLUTION: The liquid crystal display device includes a liquid crystal panel 2 having a liquid crystal layer 11 sealed between two substrates; an upper polarizing plate 3 disposed on an upper part that is the display viewing side of the liquid crystal panel 2; a reflective polarizing plate 4 set in a lower part of the liquid crystal panel 2; a selective wavelength absorption plate 5 set in a lower part of the reflective polarizing plate 4; and a light diffusion face 12 set in a lower part of the selective wavelength absorption plate 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device that performs a display operation by static drive.

  Conventionally, liquid crystal display devices have been used in personal computers, mobile phones, and the like. Liquid crystal display devices are widely used as display devices that are thin and light and have low power consumption. In recent years, when used in a mobile device such as a mobile phone, the design has been emphasized, and the demand for a liquid crystal display device capable of producing a characteristic display color has increased.

  FIG. 6 is a schematic longitudinal sectional view of a liquid crystal display device in which a mirror function is added to the display surface (see, for example, Patent Document 1). The liquid crystal display device 50 includes a liquid crystal cell 51, a front polarizing plate 55 provided on the display viewing side of the liquid crystal cell 51, a reflective polarizing plate 56 provided above the liquid crystal cell 51, and a rear polarizing plate 57 provided below the liquid crystal cell 51. And a light guide plate 52 provided in the lower portion thereof, a reflection plate 54 provided in the lower portion thereof, and a cold cathode tube 53 provided on a side surface of the light guide plate 52. In the liquid crystal cell 51, a gap is provided between the rear transparent substrate 58 and the front transparent substrate 60 via a sealing material 62, and a liquid crystal layer Lc is sealed in the gap. Further, a pixel electrode 59 is formed on the inner surface of the rear transparent substrate 58 and a counter electrode is formed on the inner surface of the front transparent substrate 60 so that an electric field can be applied to the liquid crystal layer Lc.

  Here, the reflective polarizing plate 56 has a transmission axis and a reflection axis perpendicular to each other. Light having an electric field vector in the transmission axis direction is transmitted, and light having an electric field vector in the reflection axis direction is reflected. Each of the front polarizing plate 55 and the rear polarizing plate 57 includes a transmission axis and an absorption axis that are orthogonal to each other. Transmits light having an electric field vector in the transmission axis direction and absorbs light having an electric field vector in the absorption axis direction. In the arrangement shown in FIG. 6, the transmission axis of the reflective polarizing plate 56, the transmission axis of the front polarizing plate 55, and the transmission axis of the rear polarizing plate 57 are set in the same direction. In the liquid crystal layer Lc, liquid crystal molecules are twisted, for example, by 90 ° from the surface of the front transparent substrate 60 toward the surface of the rear transparent substrate 58. In the 90 ° twisted state, the optical rotation is such that the electric field vector of light traveling from above to below or from below to above is rotated by 90 °. When the electric field is applied to the liquid crystal layer Lc and the liquid crystal molecules rise, this optical rotation is lost.

  The liquid crystal display device 50 operates as follows. First, a case where the cold cathode tube 53 is not emitting light and no voltage is applied to the counter electrode 61 and the pixel electrode 59 will be described. Of light incident from above, light having an electric field vector in the direction of the reflection axis of the reflective polarizer 56 is reflected by the reflective polarizer 56. Since the surface of the reflective polarizing plate 56 is smooth, the incident light is reflected at substantially the same angle as the incident angle. Of light incident from above, light having an electric field vector in the transmission axis direction of the reflective polarizing plate 56 is transmitted to the liquid crystal cell 51 side. The transmission axis of the front polarizing plate 55 coincides with the transmission axis of the reflective polarizing plate 56. Therefore, the light transmitted through the reflective polarizing plate 56 enters the liquid crystal cell 51. The electric field vector of the light incident on the liquid crystal layer Lc is rotated by 90 °. However, since the transmission axis of the rear polarizing plate 57 is parallel to the transmission axis of the front polarizing plate 55, the electric field vector of the light that has passed through the liquid crystal layer Lc is in the direction of the absorption axis of the rear polarizing plate 57. Is absorbed and blocked. That is, the light that has passed through the liquid crystal layer Lc is absorbed before reaching the reflection plate 54 and is not scattered upward from the liquid crystal cell 51 side. Therefore, an observer sees the light reflected from the reflective polarizing plate 56 installed on the surface of the liquid crystal display device 50, and the display surface functions as a mirror.

  Next, a case where the cold cathode tube 53 is not emitting light and a voltage is applied to the counter electrode 61 and the pixel electrode 59 will be described. When the liquid crystal layer Lc is turned on, the liquid crystal molecules rise and the optical rotation is lost in the liquid crystal layer Lc. Then, the electric field vector of the light that has passed through the front polarizing plate 55 does not rotate in the liquid crystal layer Lc and enters the rear polarizing plate 57 as it is. Since the transmission axes of the front polarizing plate 55 and the rear polarizing plate 57 are set in the same direction, the light incident on the rear polarizing plate 57 can pass through the rear polarizing plate 57. Therefore, the transmitted light that has passed through reaches the reflection plate 54 and is scattered. The scattered light follows the same path as the incident light and is emitted from the reflective polarizing plate 56 to the outside. An observer observes this scattered light.

  The reflective polarizing plate 56, the front polarizing plate 55, and the rear polarizing plate 57 usually have little wavelength dependency. The reflective polarizing plate 56 has a substantially mirror-like surface and does not have color itself. Further, the scattered light reflected by the reflecting plate 54 has little wavelength dependency. As a result, the display becomes gray on the surface of the dark mirror, and the same color system is displayed. The intensity of the light reaching the reflection plate 54 is attenuated and further attenuated when scattered upward, and this scattered light passes through the rear polarizing plate 57, the front polarizing plate 55, and the reflective polarizing plate 56. Sometimes the light intensity decreases considerably. Since the mirror surface is installed on the uppermost surface of the liquid crystal display device 50, the reflected light is obstructed, and display characters, figures, etc. with low light intensity can hardly be visually recognized.

  Next, a case where the cold cathode tube 53 is turned on to emit light will be described. Light emitted from the cold cathode tube 53 is introduced into the light guide plate 52 and spreads throughout the light guide plate 52 while being reflected on both surfaces of the light guide plate 52. Then, the light leaking from the upper surface or the lower surface of the light guide plate 52 is scattered by the reflection plate 54 and the scattered light is emitted to the liquid crystal cell 51 side. In an off state where no voltage is applied between the pixel electrode and the counter electrode, the electric field vector of the light passing through the rear polarizing plate 57 is rotated by 90 ° in the liquid crystal layer Lc. The electric field vector of the light emitted from the liquid crystal layer Lc is in the direction of the absorption axis of the front polarizing plate 55, is blocked by the front polarizing plate 55, and is not emitted outside. Therefore, the display surface is a dark mirror.

In an on state in which a voltage is applied between the pixel electrode 59 and the counter electrode 61, the liquid crystal molecules in the liquid crystal layer Lc rise and lose optical rotation. Therefore, the light that has passed through the liquid crystal layer Lc can pass through the front polarizing plate 55 and the reflective polarizing plate 56. Therefore, the observer can visually recognize white characters and images on the mirror display surface.
JP 2004-246004 A

  As described above, in the conventional example, since the reflective polarizing plate 56 is installed at the uppermost part, the external light incident on the display surface is always reflected. Therefore, when the cold cathode fluorescent lamp 53 is turned off to display in the reflective type, the characters and images displayed on the mirror display surface are the same color system as the mirror display surface and are hardly visible. There was a problem. Even when the cold-cathode tube 53 is turned on to perform transmissive display, the uppermost part always functions as a mirror, so that the display is difficult to recognize depending on the surrounding environment, or the light source is a cold-cathode. Since the tube 53 is used, there is a problem that the same color system gray is displayed on the dark mirror and the visibility is low.

  In order to solve the above problems, the following measures are taken in the present invention.

  (1) A liquid crystal panel in which a liquid crystal layer is sealed between two substrates, a polarizing plate installed on the upper side of the liquid crystal panel on the display viewing side, and a reflective polarizing plate installed on the lower side of the liquid crystal cell; The liquid crystal display device is composed of a selective wavelength absorbing plate installed under the reflective polarizing plate and a light scattering surface installed under the selective wavelength absorbing plate.

  (2) In the liquid crystal display device according to (1), the liquid crystal display device further includes a light guide plate installed below the selective wavelength absorbing plate, and a light source for introducing light into the light guide plate, and the upper surface or the lower surface of the light guide plate is provided. The light scattering surface was used.

(3) In the liquid crystal display device of (1) or (2), the selective wavelength absorbing plate is an electric field controlled birefringence type liquid crystal cell.
(4) In the liquid crystal display device according to any one of the above (1) to (3), the light source is a plurality of light emission sources having different emission colors.

  By installing the reflective polarizing plate on the side opposite to the viewing side of the liquid crystal panel, one of the display part that displays characters and images on the display surface and the background part becomes a mirror-like reflection surface, and the other is specular. Since the reflective surface is released, the visibility of the display is improved even in the reflective display. In addition, by providing a selective wavelength absorbing plate between the reflective polarizing plate and the light scattering surface, it is possible to add color to a region other than the display surface being a mirror-like reflective surface. It has the advantage that the property can be improved.

  In the liquid crystal display device of the present invention, a liquid crystal panel in which a liquid crystal layer is sealed between two substrates, an upper polarizing plate provided on an upper part which is a display viewing side of the liquid crystal panel, and a display viewing side of the liquid crystal panel are The reflective polarizing plate is provided at the lower part on the opposite side, the selective wavelength absorbing plate is provided below the reflective polarizing plate, and the light scattering surface is provided below the selective wavelength absorbing plate.

  As the liquid crystal panel, a TN liquid crystal panel, an STN liquid layer panel, a TFT liquid crystal panel, an in-plane switching type liquid crystal panel, or the like can be used. As the selective wavelength absorbing plate, a color filter film using a dye-based color filter, a selective transmission film using cholesteric liquid crystal, an electric field control birefringence type liquid crystal cell, or the like can be used. As the light scattering surface, it is possible to use a light diffusion plate having a rough surface, a light diffusion plate in which light scattering particles are mixed in a transparent resin, a light diffusion plate having irregularities on the surface of a transparent resin or transparent glass, and the like. it can. In addition, a light guide plate may be provided below the selective wavelength absorption plate, and unevenness may be provided on the upper surface or the lower surface of the light guide plate to form a light scattering surface.

  The liquid crystal display device of the present invention can perform a display operation as a reflection type. When no voltage is applied to the liquid crystal panel, light incident from the outside passes through the selective wavelength absorbing plate, is scattered by the light scattering surface, passes through the selective wavelength absorbing plate again, and is emitted from the uppermost polarizing plate. The When voltage is applied, external light reflected by the surface of the reflective polarizing plate is emitted from the uppermost polarizing plate. Therefore, the display surface displays mirror characters and figures on a color background. In this case, the mirror-like reflection from the reflective polarizing plate is blocked in the background area with a color display surface. Further, by changing the direction of the polarization direction (transmission axis) of either the polarizing plate or the reflective polarizing plate, it is possible to display colored characters and figures on the background of the mirror surface. Also in this case, the mirror-like reflection from the reflective polarizing plate is blocked in the area where the color characters and figures are displayed. Therefore, a display with improved visibility can be obtained.

  In addition, a light guide plate may be provided below the selective wavelength absorption plate, and a light source for introducing light into the light guide plate may be provided to provide a light emitting liquid crystal display device. When no voltage is applied to the liquid crystal panel, the external light scattered through the light diffusing surface through the selective wavelength absorbing plate and the light emitted from the light guide plate pass through the selective wavelength absorbing plate, so the display surface is bright Color background. When a voltage is applied to the liquid crystal panel, the diplomacy reflected by the surface of the reflecting surface polarizing plate is emitted from the uppermost polarizing plate. However, the light emitted from the light guide plate is blocked by the polarizing plate installed on the uppermost surface. Therefore, the display surface displays mirror characters and figures on a bright color background. In addition, by changing the polarization direction of either the polarizing plate or the reflective polarizing plate, bright colored characters and figures can be displayed on the mirror background.

  In addition, by making the selective wavelength absorption plate an electric field control birefringence type liquid crystal cell (hereinafter referred to as ECB liquid crystal cell), a background color or display when no voltage is applied to the liquid crystal layer or when a voltage is applied to the liquid crystal layer The color can be changed arbitrarily. Further, the light source can be a plurality of light emission sources having different emission colors. Further, if each light source can be controlled independently, the background color or the display color of the display surface can be selected as appropriate, so that a variety of displays with various changes can be obtained.

Hereinafter, the present invention will be described in detail with reference to the drawings.
(Embodiment 1) FIG. 1 is a longitudinal sectional view of a liquid crystal display device 1 according to Embodiment 1 of the present invention. The liquid crystal display device 1 includes a liquid crystal panel 2, an upper polarizing plate 3 provided on the display viewing side of the liquid crystal panel 2, a reflective polarizing plate 4 provided on the lower side of the liquid crystal panel 2 opposite to the display viewing side, A selective wavelength absorbing plate 5 provided at the lower portion, a light guide plate 6 provided at the lower portion thereof, and a light source 7 provided at a side portion of the light guide plate 6 are configured. The upper surface of the light guide plate 6 is subjected to a concavo-convex process to form a light scattering surface 12. In the liquid crystal panel 2, a lower transparent substrate 8 and an upper transparent substrate 9 are bonded together with a sealing material 10, and a liquid crystal layer 11 is formed inside. A plurality of stripe-shaped lower transparent electrodes 14 are formed on the liquid crystal layer 11 side of the lower transparent substrate 8, and a plurality of stripe-shaped upper transparent electrodes 15 are also formed on the liquid crystal layer 11 side of the upper transparent substrate 9. Yes. The lower transparent electrode 14 and the upper transparent electrode 15 are formed so as to intersect with each other, and an electric field can be selectively applied to the liquid crystal layer 11. The liquid crystal layer 11 is a 90 ° twisted TN type. The selective wavelength absorption plate 5 is composed of a film in which a pigment or dye is mixed in a resin layer, and transmits light having a specific wavelength, for example, a wavelength λ10.

  In FIG. 1, no electric field is applied to the liquid crystal layer 11 on the left side of the liquid crystal display device 1, and the liquid crystal layer 11 is in an off state. An electric field is applied to the right liquid crystal layer 11, and the liquid crystal layer 11 is in an on state. In the off state, incident light I incident from the display viewing side passes through the upper polarizing plate 3, the liquid crystal panel 2, the reflective polarizing plate 4, and the selective wavelength absorbing plate 5 and reaches the light scattering surface 12. Furthermore, a part of the scattered light scattered from the light scattering surface 12 can be visually recognized as reflected light Roff after passing through the selective wavelength absorbing plate 5, the reflective polarizing plate 4, the liquid crystal panel 2, and the upper polarizing plate 3. . Since the reflected light Roff passes through the selective wavelength absorption plate 5 twice, the color of the selective wavelength absorption plate 5 is obtained.

  On the other hand, in the ON state, the incident light I incident from the display viewing side is specularly reflected by the reflective polarizing plate 4 after passing through the upper polarizing plate 3 and the liquid crystal panel 2. Then, it can be visually recognized as reflected light Ron after passing through the liquid crystal panel 2 and the upper polarizing plate 3. Since the reflected light Ron does not pass through the selective wavelength absorbing plate 5, the color tone of the upper polarizing plate 3 and the reflective polarizing plate 4 is obtained. However, the transmitted light or reflected light of the upper polarizing plate 3 and the reflective polarizing plate 4 has little wavelength dependency, and the surface of the reflective polarizing plate 4 is smooth, so that the reflected light Ron is non-colored specular reflection. Therefore, a region where no voltage is applied to the liquid crystal layer 11 becomes a colored region of the color of the selective wavelength absorption plate 5, and a region of characters or figures to which a voltage is applied becomes a mirror surface. By selecting the color of the selective wavelength absorbing plate 5, it is possible to obtain reflective displays with various designs.

  Further, the display state can be reversed by changing the relative angle between the transmission axis of the upper polarizing plate 3 and the reflection axis of the reflective polarizing plate 4 (for example, one of them is rotated by 90 °). That is, a region where no voltage is applied to the liquid crystal layer 11 can be used as specular reflection, and a region where a voltage is applied can be used as the colored region of the selective wavelength absorption plate 5. In any of the display methods, since the specular reflection light of the reflective polarizing plate 4 does not cover the colored region of the selective wavelength absorption plate 5, the display visibility of the reflective display is improved.

  FIG. 2 is an explanatory diagram of the operation principle when the light source 7 is turned off to make a reflective display. 2A corresponds to the left side of FIG. 1 and is an explanatory diagram of an off state in which no electric field is applied to the liquid crystal layer 11. FIG. 2B corresponds to the right side of FIG. It is explanatory drawing of the applied ON state. First, in FIG. 2A, incident light I having wavelengths λ1 to λ10 is incident in the −z direction. The transmission axis of the upper polarizing plate 3 is set in the P direction (for example, 45 ° from the x axis) in the xy plane. The light that has passed through the upper polarizing plate 3 becomes a polarized light beam whose electrolytic vector is in the P direction. The liquid crystal molecules 13 of the liquid crystal layer 11 are twisted so as to rotate 90 ° from the upper surface toward the lower surface. The liquid crystal layer 11 is optically set so that the electric field vector of the incident light rotates by 90 °. Therefore, the light incident on the liquid crystal layer 11 is emitted as a polarized light beam in the Q direction with the electric field vector rotated by 90 °. The reflective polarizing plate 4 is installed with the transmission axis in the Q direction and the reflection axis in the P direction perpendicular to it. Since the polarized light beam in the Q direction emitted from the liquid crystal layer 11 has an electric field vector in the transmission axis direction of the reflective polarizing plate 4, it passes through the reflective polarizing plate 4. The selective wavelength absorbing plate 5 transmits the wavelength λ10 and absorbs the other wavelengths λ1 to λ9. Therefore, the light Ix (λ10) having the wavelength λ10 reaches the light scattering surface 12.

  On the light scattering surface 12, the scattered light S (λ10) having the wavelength λ10 is scattered upward. Since the polarization direction of light is hardly affected, the electric field vector of the scattered light S (λ10) is in the Q direction. The scattered light S (λ10) passes through the selective wavelength absorbing plate 5 again, and passes through the reflection polarizing plate 4 because the transmission axis is the Q direction, and the electric field vector rotates 90 ° in the liquid crystal layer 11 to cause polarization in the P direction. It is emitted as a light beam. Since the upper polarizing plate 3 has a transmission axis in the P direction, the upper polarizing plate 3 also passes through and the reflected light Rx (λ10) having the wavelength λ10 is reflected upward.

  Next, in FIG. 2B, incident light I (λ1 to λ10) having wavelengths λ1 to λ10 is incident in the −z direction. Since the transmission axis of the upper polarizing plate 3 is in the P direction, a polarized light beam having an electric field vector in the P direction enters the liquid crystal layer 11. The liquid crystal layer 11 loses its optical rotation because liquid crystal molecules rise when an electric field is applied. Therefore, the light passing through the liquid crystal layer 11 has an electric field vector in the P direction. Since the reflection axis of the reflective polarizing plate 4 is in the P direction, it is reflected upward as reflected light R (λ1 to λ10) having wavelengths λ1 to λ10, and is not transmitted downward. The reflected light R (λ1 to λ10) passes through the liquid crystal layer 11 that has lost its optical rotation and reaches the upper polarizing plate 3 as it is. Since the transmission axis of the upper polarizing plate 3 is also in the P direction, it passes through the upper polarizing plate 3 and is emitted upward as reflected light Rx (λ1 to λ10). In this case, the wavelength of the light is the same as the incident light and has λ1 to λ10.

  As described above, the display surface of the liquid crystal display device 1 according to the first embodiment has the wavelength λ <b> 1 to λ <b> 10 reflected by the reflective polarizing plate 4 on the background of the color tone provided by the selective wavelength absorption plate 5, for example, the color λ <b> 10. Thus, characters, figures, etc. are displayed by specular reflection light. When the transmission axis of the upper polarizing plate 3 is rotated by 90 ° or the transmission axis of the reflective polarizing plate 4 is rotated by 90 °, the display color is reversed. In other words, characters, figures, and the like colored by the selective wavelength absorbing plate 5 can be displayed on the background of the specular reflection light. In any display method, when the incident light I (λ1 to λ10) passes through the liquid crystal layer 11 and passes through the reflective polarizing plate 4 and reaches the light scattering surface 12, the transmitted light passes through the liquid crystal layer 11. Since the light having the electric field vector in the direction of the reflection axis of the reflective polarizing plate 4 is not included, the intensity of the light reflected from the reflective polarizing plate 4 to the display viewing side is weak. Therefore, the reflected light R (λ1 to λ10) from the reflective polarizing plate 4 does not overlap the scattered light Sx (λ10).

  FIG. 3 additionally shows an optical path when the liquid crystal display device 1 according to the first embodiment shown in FIG. The configuration of the liquid crystal display device 1 is the same as that in FIG. The light source 7 is turned on to introduce light into the light guide plate 6. A light scattering surface 12 is formed on the surface of the light guide plate 6. The backlight B emitted from the scattering surface is indicated by a broken line. First, in the left off state where no electric field is applied to the liquid crystal layer 11, the backlight light B scattered from the light scattering surface 12 is colored through the selective wavelength absorbing plate 5 and enters the reflective polarizing plate 4. . In the reflective polarizing plate 4, a part of the backlight light B is reflected and a part of the backlight light B is transmitted. The backlight B transmitted through the reflective polarizing plate 4 is transmitted as the backlight Boff through the liquid crystal layer 11 and the upper polarizing plate 3. Therefore, the observer observes light in which the reflected light Roff by the incident light I incident from the outside and the backlight light Boff are additively mixed. Various display surfaces can be obtained by appropriately selecting the color of the backlight light and the color of the selective wavelength absorption plate 5.

  On the other hand, in the ON state, the backlight light emitted from the light scattering surface of the light guide plate 6 passes through the selective wavelength absorbing plate 5, and part of the light is transmitted through the reflective polarizing plate 4 and passes through the liquid crystal panel 2. can do. However, since the transmission axis direction of the reflective polarizing plate 4 and the absorption axis direction of the upper polarizing plate 3 are in the same direction, the backlight transmitted through the reflective polarizing plate 4 is blocked by the upper polarizing plate 3. That is, the backlight light B is not emitted to the outside. Therefore, a mirrored character or figure is displayed against a bright color background. By selecting the color of the selected wavelength absorption plate 5 and the emission color of the light source 7, transmissive displays with various designs can be obtained.

  FIG. 4 is an explanatory diagram of the operation principle when the light source 7 is turned on to achieve transmissive display. 4A corresponds to the left side of FIG. 3 and is an explanatory diagram of an off state in which no electric field is applied to the liquid crystal layer 11. FIG. 4B corresponds to the right side of FIG. It is explanatory drawing of the applied ON state. The path of the backlight light B (λ1 to λ10) is indicated by a broken line. FIG. 4 also shows incident light I incident from the outside, and accompanying scattered light S (λ10) and reflected light R (λ1 to λ10), which are the same as those in FIG.

  In FIG. 4A, backlight light B (λ1 to λ10) having wavelengths λ1 to λ10 is emitted in the z direction. The light having the wavelength λ10 is transmitted through the selective wavelength absorbing plate 5 that transmits the light wavelength λ10. In the reflective polarizing plate 4, the P direction is the reflection axis and the Q direction is the transmission axis on the xy plane. Therefore, the backlight light B (λ10) whose electric field vector is in the P direction is reflected, and the backlight light B (λ10) whose electric field vector is in the Q direction is transmitted. In the backlight light B (λ10), the electric field vector of the light rotates by 90 ° in the liquid crystal layer 11, and the polarized light having the electric field vector in the P direction is incident on the upper polarizing plate 3. Since the transmission axis of the upper polarizing plate 3 is the P direction, the backlight light B (λ10) passes through the upper polarizing plate 3 and is emitted upward. As a result, together with the backlight light B (λ10) having the wavelength λ10, the incident light I incident from the outside is emitted together with the scattered light Sx (λ10) scattered on the light scattering surface 12. Various designs can be configured by selecting the emission color of the light source 7 and the color of the selective wavelength absorption plate 5. In addition, since the light reflected by the reflective polarizing plate 4 is returned to the light guide plate 6, this return light is reused.

  In FIG. 4B, backlight light B (λ1 to λ10) having wavelengths λ1 to λ10 is emitted in the z direction. The backlight B (λ10) passes through the selective wavelength absorbing plate 5 that transmits the light wavelength λ10, and has a color tone of the wavelength λ10. Since the reflection polarizing plate 4 has a reflection direction in the P direction, light whose electric field vector is in the P direction is reflected, and light whose electric field vector is in the Q direction is transmitted. Since the optical rotation is lost in the liquid crystal layer 11, the backlight light B (λ 10) having an electric field vector in the Q direction is incident on the upper polarizing plate 3. Since the transmission axis of the upper polarizing plate 3 is the P direction and the absorption axis is the Q direction, the backlight B (λ10) is blocked by the upper polarizing plate 3 and is not emitted to the outside. That is, when the liquid crystal layer 11 is in the on state, the reflected light R (λ1 to λ10) based on the incident light I (λ1 to λ10) incident from the outside is emitted. The reflected light has a specular color tone. Therefore, a character or a figure based on the specular reflection of the reflected light Rx (λ1 to λ10) against the background of the color tone of the wavelength λ10 obtained by additively mixing the scattered light S (λ10) and the backlight light B (λ10) based on the incident light. Can see. In addition, the display surface of various designs can be comprised by selecting the luminescent color of the light source 7, and the color of the selection wavelength absorption board 5. FIG. Further, the display state can be reversed by rotating the transmission axes of the upper polarizing plate 3 and the reflective polarizing plate 4 by 90 ° relative to each other.

  As described above, in the first embodiment described with reference to FIGS. 1 to 4, the scattered light Sx attenuates at the upper polarizing plate 3, the reflective polarizing plate 4, the selective wavelength absorption plate 5, and the light scattering surface 12, so that the light intensity is increased. become weak. Therefore, in the transmissive display in which the light source 7 is turned on, the background is mainly the backlight light Bx, and the color tone is determined by the backlight light B (λ1 to λ10) and the light transmission characteristics of the selected wavelength absorber 5. . In the first embodiment, the TN liquid crystal panel in which the liquid crystal layer 11 is twisted by 90 ° has been described. However, an STN liquid crystal panel or an IPS liquid crystal panel twisted by 180 ° or more can be used. Further, the normally white liquid crystal display device 1 in which the white level is obtained when no electric field is applied to the liquid crystal layer 11 has been described. Instead, the installation angle of the upper polarizing plate 3 or the reflective polarizing plate 4 is set to 90 °. It can be a normally black type rotated. In this case, as already described, the voltage application state and the non-application state are reversed.

  (Embodiment 2) FIG. 5 is a schematic longitudinal sectional view of a liquid crystal display device 1 according to Embodiment 2 of the present invention. In this embodiment, an ECB liquid layer cell is used as the selective wavelength absorption plate 5, and red (R) green (G) blue (B) emission colors can be independently controlled as the light source 7. The same part or the part having the same function is denoted by the same reference numeral.

  As shown in FIG. 5, the liquid crystal display device 1 includes a liquid crystal panel 2, an upper polarizing plate 3 provided on the display viewing side above the liquid crystal panel 2, a reflective polarizing plate 4 provided on the opposite side, and a lower portion thereof. It comprises a selective wavelength absorption plate 5 provided, a light guide plate 6 provided therebelow, and a light source 7 for introducing light into the light guide plate 6. In the liquid crystal panel 2, a lower transparent substrate 8 and an upper transparent substrate 9 are bonded together with a sealing material 10, and a liquid crystal layer 11 is formed in the gap. A light scattering surface 12 (not shown) is formed on the upper or lower surface of the light guide plate 6.

  The selective wavelength absorption plate 5 is composed of an ECB liquid crystal cell. The ECB liquid crystal cell has a configuration in which two transparent substrates 21a and 21b are bonded together with a sealing material 23, and a liquid crystal layer 24 is filled in a gap therebetween. Transparent electrodes made of ITO, ZnO or the like are formed on the entire inner surfaces of the two transparent substrates 21a and 21b. Polarizing plates 20a and 20b are attached to the outer surfaces of the two transparent substrates 21a and 21b. The liquid crystal layer 24 is oriented so that liquid crystal molecules are uniformly twisted or twisted from the upper surface of the transparent electrode 21b toward the lower surface of the transparent electrode 21a. The polarization direction of the polarizing plate 20b (transmission axis direction) and the polarization direction of the polarizing plate 20a are approximately 45 ° with respect to the alignment direction of the liquid crystal molecules on the upper surface of the liquid crystal layer 24 and the alignment direction of the liquid crystal molecules on the lower surface. Make an angle. When light enters this ECB liquid crystal cell, wavelength selectivity appears in the transmitted light due to the birefringence of the liquid crystal molecules. Furthermore, by applying a driving voltage 25 to the transparent electrodes 22a and 22b, the birefringence in the liquid crystal layer 24 can be changed, and the color of the transmitted light can be changed.

  Further, the light source 7 includes an RGB light source, and the drive currents 26a, 26g, and 26b can be controlled independently. Specifically, R-LED7R, G-LED7G, and B-LED7B are provided.

  When the liquid crystal display device 1 is used as a reflective display, the background color of the display surface can be arbitrarily changed by changing the drive voltage 25. Further, when used as a light-emitting display, it is possible to emit a desired color by adjusting the drive currents 26a, 26g, and 26b. In addition, by appropriately selecting the drive voltage 25 applied to the ECB liquid crystal cell and the drive currents 26a, 26b, and 26b applied to the light source 7, the user can set the display surface to a favorite color, which is rich in change. You can get a variety of displays.

  The liquid crystal display device 1 according to the present invention described above is not limited to the above configuration, and has, for example, the same transmission axis direction as the transmission axis direction of the reflective polarizing plate 4 between the liquid crystal panel 2 and the reflective polarizing plate 4. A polarizing plate may be inserted, or an optical film or the like may be inserted between the liquid crystal panel 2 and the light guide plate 6. Moreover, it cannot be overemphasized that it can replace with the side mirror type which installed the light source 7 in the side surface of the light-guide plate 6 as a backlight, and can be set as the light source by electroluminescence or a cold cathode tube.

It is a typical longitudinal cross-sectional view of the liquid crystal display device based on the Example of this invention. It is explanatory drawing explaining the principle of operation of the liquid crystal display device based on the Example of this invention. It is a typical longitudinal cross-sectional view of the liquid crystal display device based on the Example of this invention. It is explanatory drawing explaining the principle of operation of the liquid crystal display device based on the Example of this invention. It is a typical longitudinal cross-sectional view of the liquid crystal display device based on the Example of this invention. It is a typical longitudinal cross-sectional view of a conventionally well-known liquid crystal panel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal panel 3 Upper polarizing plate 4 Reflective polarizing plate 5 Selection wavelength absorption plate 6 Light guide plate 7 Light source 8 Lower transparent substrate 10 Sealing material 11 Liquid crystal layer 12 Light scattering surface

Claims (4)

  A liquid crystal panel in which a liquid crystal layer is sealed between two substrates, a polarizing plate installed on the upper part on the display viewing side of the liquid crystal panel, a reflective polarizing plate installed on the lower part of the liquid crystal panel, and the reflection A liquid crystal display device comprising a selective wavelength absorbing plate installed under a polarizing plate and a light scattering surface installed under the selective wavelength absorbing plate.   The light guide plate further provided at a lower portion of the selective wavelength absorption plate and a light source for introducing light into the light guide plate, wherein an upper surface or a lower surface of the light guide plate is the light scattering surface. 2. A liquid crystal display device according to 1.   The liquid crystal display device according to claim 1, wherein the selective wavelength absorption plate is an electric field controlled birefringence type liquid crystal cell.   The liquid crystal display device according to claim 1, wherein the light source includes a plurality of light emitting sources having different emission colors.

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