JP2008191494A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve display contrast, and to use a conventional polarizing plate, in a liquid crystal display device having a liquid crystal display panel with a phosphor layer arranged therein so as to improve its viewing angle dependence, by reducing light leakage in the off-state of the display. <P>SOLUTION: The liquid crystal display device includes: a liquid crystal cell 3; an illuminator 8; an incident side polarizing plate 2p disposed between the liquid crystal cell 3 and the illuminator 8; a light outgoing side polarizing plate 2a disposed on the liquid crystal cell 3 on the side opposite to the illuminator 8; and a phosphor plate 1 disposed on the light outgoing side polarizing plate 2a and emitting light by being exited with light emitted from the illuminator 8, wherein a full angular width at half maximum θw of light incident on the liquid crystal cell 3 is ≤ about 20° with respect to a predetermined direction on the surface of the liquid crystal cell 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a phosphor layer that emits light having a wavelength different from that of light emitted from an illumination device.

  Liquid crystal display devices have been put into practical use as display units for flat-screen televisions and mobile phones. The liquid crystal display device includes a pair of polarizing plates that sandwich the liquid crystal cell, a backlight that emits light from the lower portion of the liquid crystal cell, and the like. The liquid crystal cell has a configuration in which a liquid crystal layer is sandwiched between a pair of transparent substrates having transparent electrodes formed on the inner surface. In the liquid crystal layer, liquid crystal molecules are twisted and aligned from the lower transparent electrode toward the upper transparent substrate. The twist angle of the liquid crystal molecules is usually set to about 90 ° in the case of an active liquid crystal panel using TFT or the like, and about 90 ° or about 180 ° to 270 ° in the case of a simple matrix type liquid crystal panel. Yes.

  When no voltage is applied to the liquid crystal layer, the linearly polarized light after passing through the incident-side polarizing plate where light enters is rotated by about 90 ° or about 180 ° to 270 ° according to the twist of the liquid crystal molecules. The light passing through the liquid crystal layer is blocked when the polarization axes of the exit-side polarizing plate and the incident-side polarizing plate are in the same direction, and is transmitted when they are in the directions orthogonal to each other. On the other hand, when a voltage is applied to the transparent electrode, the liquid crystal molecules rise in a direction perpendicular to the substrate surface. Then, it becomes impossible to rotate the polarized light incident on the liquid crystal layer. As a result, when the polarization axes of the incident-side polarizing plate and the outgoing-side polarizing plate are parallel to each other, the light passing through the liquid crystal layer is transmitted, and when they are orthogonal to each other, the light passing through the liquid crystal layer is blocked. The Thereby, the light passing through the liquid crystal cell can be controlled by the voltage applied to the transparent electrode.

  However, the light passing through the liquid crystal layer cannot rotate along the rotation of the liquid crystal molecules over the entire wavelength range of visible light, and the polarization characteristics of the polarizing plate also have wavelength dependency. For this reason, it is difficult to completely block light passing through the liquid crystal panel, which causes a decrease in contrast. In order to improve this, there is a method in which a phase difference plate is provided to perform optical compensation. However, the thickness of the liquid crystal panel is increased and the cost is increased. Further, a color filter is provided in each pixel for performing color display. The color filter has a property of passing only light having a necessary wavelength and blocking other light. Therefore, the utilization efficiency of incident light is reduced.

  In order to improve such a problem, a liquid crystal display device provided with a phosphor layer has been proposed (see, for example, Patent Document 1). FIG. 7 is a cross-sectional view of a liquid crystal display device in which the phosphor layer 110 is formed on the liquid crystal layer side. A liquid crystal panel 100 is formed by sandwiching the liquid crystal layer 100 between the lower substrate 101 and the upper substrate 102. The lower substrate 101 has a configuration in which a lower transparent electrode 105 and an alignment film 106 are sequentially formed on a lower substrate body 104. The upper substrate 102 has a configuration in which a phosphor layer 110, an emission side polarizing layer 109, an upper transparent electrode 108, and an alignment film 107 are sequentially formed on an upper substrate body 111. An incident side polarizing plate 103 is disposed below the lower substrate 101, and a backlight 113 is disposed below the incident side polarizing plate 103. The phosphor layer 110 receives ultraviolet light emitted from the backlight 113 and emits red light as excitation light, a phosphor layer 110G that emits green light as excitation light, and excitation light. As shown, a phosphor layer 110B that emits blue light is formed corresponding to each pixel.

With such a configuration, ultraviolet light with a narrow wavelength bandwidth passes through the liquid crystal layer 100, so that light leakage due to wavelength dispersion of light passing through the liquid crystal layer 100 is reduced, and a color filter is not provided. Color display can be performed.
JP 2005-274673 A

  However, the liquid crystal panel 114 has viewing angle dependency. That is, even if incident light can be blocked in the vertical direction, there is an angle at which light leaks with respect to obliquely incident light. For example, focusing on the phosphor layer 110 </ b> R, when incident light emitted from the backlight 113 passes through the liquid crystal layer 100 vertically and reaches the output-side polarizing layer 109, the incident light is transmitted by the output-side polarizing layer 109. Even if blocked, the incident light that has passed through the liquid crystal layer 100 obliquely and reached the output-side polarizing layer 109 is not completely blocked by the output-side polarizing layer 109, and part of the incident light leaks and the phosphor layer 110R is irradiated. As a result, unnecessary excitation light is emitted from the phosphor layer 110R. This causes a decrease in the contrast of the display image.

  In addition, the phosphor layer 110 is formed on the liquid crystal layer 100 side of the upper substrate body 111 in order to prevent display quality from deteriorating, such as display overlapping between adjacent pixels and blurring of pixel outlines. Therefore, it is necessary to provide the output side polarizing layer 109 between the phosphor layer 110 and the liquid crystal layer 100. Such an exit-side polarizing layer 109 is formed by applying a special liquid crystal material on the phosphor layer 110 while applying stress, and its polarization characteristics are not sufficient as compared with a general polarizing plate. . In addition, since it must be formed by a special manufacturing method, the manufacturing cost increases.

  In order to solve the above problems, the present invention provides a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes formed on the inner surface, an illumination device for irradiating light to the liquid crystal cell, and the liquid crystal cell And an incident side polarizing plate disposed between the lighting device, an output side polarizing plate disposed on the liquid crystal cell opposite to the lighting device, and the output side polarizing plate. A phosphor plate that is excited by the light emitted from the illumination device and emits light, and the full width at half maximum of incident light emitted from the illumination device and incident on the liquid crystal cell is specified on the surface of the liquid crystal cell. It was set as the liquid crystal display device which is within about 20 degrees with respect to this direction.

  Moreover, the light radiate | emitted from an illuminating device was made into blue light. Moreover, the touch panel was arrange | positioned on the output side polarizing plate. In addition, a reflective polarizing plate is used as the output side polarizing plate.

  According to the present invention, the phosphor layer is provided on the side of the liquid crystal cell on the side where the liquid crystal display is viewed, and the directivity of the light irradiated from the illumination device and incident on the liquid crystal cell is about 20 ° full width at half maximum. did. As a result, the oblique light passing through the liquid crystal cell is reduced, the phosphor layer is excited by the oblique light and the contrast can be suppressed, and the polarizing layer needs to be formed in the liquid crystal cell. This has the advantage that it is easy to manufacture.

  The liquid crystal display device of the present invention includes a liquid crystal cell sandwiched between an incident side polarizing plate and an outgoing side polarizing plate, an illumination device provided on the incident side polarizing plate side, and a phosphor provided above the outgoing side polarizing plate. The full width at half maximum of incident light emitted from the illumination device and incident on the liquid crystal cell is within approximately 20 ° with respect to a specific direction on the surface of the liquid crystal cell. With such a configuration, light in an oblique direction passing through the liquid crystal layer is reduced, and a reduction in contrast can be prevented.

  Further, the light emitted from the illumination device is configured to be blue light. In addition, a touch panel is arranged above the output side polarizing plate. A phosphor is formed on the surface of the touch panel.

  A plurality of types of phosphors having different emission colors are arranged so as to correspond to the unit pixels of the liquid crystal cell. Thereby, multicolor display becomes possible.

Hereinafter, embodiments of the liquid crystal display device according to the present invention will be described in detail.
<Example 1>
FIG. 1 schematically shows a cross-sectional configuration of the liquid crystal display device 10 of the present embodiment. As shown in the figure, the liquid crystal panel 4 has a configuration in which the liquid crystal cell 3 is sandwiched between the incident side polarizing plate 2p and the outgoing side polarizing plate 2a. The liquid crystal cell 3 has a configuration in which a liquid crystal layer is sandwiched between a pair of translucent substrates. Transparent electrodes are formed on the inner surfaces of the pair of translucent substrates so that a voltage can be applied to the liquid crystal layer. An illuminating device 8 that irradiates the liquid crystal panel 4 with light is disposed below the liquid crystal panel 4. The illumination device 8 reflects the light emitted from the light source 7, the light guide plate 5 that guides the light emitted from the light source 7 and emits the light toward the liquid crystal panel 4, and the light emitted from below the light guide plate 5 to the light guide plate side. The reflecting plate 6 is provided. Here, the full width at half maximum of incident light emitted from the illumination device 8 and incident on the liquid crystal cell 3 is within about 20 ° with respect to a specific direction on the surface of the liquid crystal panel 4.

  With such a configuration, light in an oblique direction passing through the liquid crystal layer of the liquid crystal cell 3 is reduced, and the viewing angle dependency of light passing through the liquid crystal panel 4 can be reduced. As a result, the light incident obliquely on the phosphor plate 1 is reduced, the black level is improved, and a display with an improved contrast ratio can be obtained. Moreover, since the polarizing plate normally used between the fluorescent substance plate 1 and the liquid crystal cell 3 can be used, it becomes unnecessary to form a polarizing plate in a liquid crystal cell with a special manufacturing method, and improves a polarization characteristic. And can be manufactured easily. In addition, since light is emitted from the uppermost surface of the liquid crystal display device, a display having no viewing angle dependency can be obtained.

  Here, a light emitting diode (hereinafter referred to as LED) that emits blue emitted light 9 is used as the light source 7. The phosphor plate 1 can be made of a material that emits blue light and excites red light or a material that excites green light. Moreover, the material which injects blue light and excites red light and green light can be used. In this case, a part of the incident blue light is transmitted, and the other part of the incident light emits red light and green light as excitation light, whereby white light in which each color light is additively mixed is displayed as display light. 11 can be emitted. Since the phosphor plate 1 itself emits light, the display can be viewed from any direction, and a display having no viewing angle dependency can be obtained. In addition, since the light passing through the polarizing plate is monochromatic light, a polarizing plate having a high polarization rate can be used. Furthermore, since monochromatic light passes through the liquid crystal layer, the rotation angle in the polarization direction is not dispersed by the wavelength. As a result, for example, in the case of a normally-off liquid crystal panel that does not transmit light when no voltage is applied, leakage light is reduced, so that a high-contrast display can be obtained.

  Further, no translucent material such as glass is provided on or below the phosphor plate 1. For this purpose, display light emitted from the phosphor plate 1 in an oblique lateral direction can be used. When a translucent material such as glass is installed on top of the phosphor plate 1, the oblique light emitted from the phosphor is totally reflected on the surface of the translucent material and cannot be used as display light. In the embodiment, such a phenomenon does not occur. Therefore, the use efficiency of light emission by the phosphor can be increased as compared with the liquid crystal display device with a phosphor layer shown in FIG.

Examples of the phosphor plate 1 include a translucent substrate having a phosphor layer formed on the surface and a translucent substrate in which a phosphor material is dispersed or dissolved. Moreover, this translucent base | substrate can be used also as a transparent cover of the portable apparatus carrying a liquid crystal display device. As the phosphor material, an inorganic or inorganic phosphor material can be used. When a blue light LED is used as the light source 7, a material that emits red light when excited by incident blue light as a phosphor material, for example, (Sr, Ca) S: Eu, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, CaSiN ₂ : Eu, CaAlSiN ₃ : Eu, or the like can be used. Further, emits green light by excitation with blue _{light, Y 3 (Al, Ca)} 5 O 12: Ce, SrCa 2 S 4: Eu, Ca 3 Se 2 Si 3 O 12: Ce, Sr-SiON: Eu Etc. can be used. Excited with blue light to emit yellow light, (Y, Gd) _{3 Al 5} O ₁₂ : Ce, Tb _{3 Al 5} O ₁₂ : Ce, CaGa ₂ S ₄ : Eu, Sr ₂ SiO ₄ : Eu, Cax ( Si, Al) ₁₂ (O, N) ₁₆ : Eu or the like can be used. If this phosphor material is used, a part of the incident blue light and the emitted yellow light are additively mixed and emitted as white light.

  Further, an ultraviolet LED that emits near-ultraviolet light can be used as the light source 7. As the phosphor material, a phosphor material that emits red light, green light, and blue light when excited by ultraviolet light can be used. However, when ultraviolet light is used as a light source, it is necessary to take measures to prevent deterioration of the polymer material, particularly the liquid crystal material and the polarizing plate due to ultraviolet light.

  FIG. 2 is an explanatory diagram for explaining the lighting device 8 used in the present invention, FIG. 2 (a) is a perspective view of the lighting device 8, and FIG. 2 (b) is a light guide plate 5 and a reflecting plate 6. FIG. The same parts or parts having the same function are denoted by the same reference numerals.

  As shown in FIG. 2A, the illuminating device 8 includes a light source 7 composed of an LED that emits blue light, and a light guide plate 5 having a concavity or groove pattern 14 formed concentrically on the lower surface. A reflection plate 6 is provided that reflects light emitted from the light guide plate 5 in a direction perpendicular to the plate surface. The light guide plate 5 is made of a synthetic resin such as acrylic or polycarbonate, or an inorganic material such as glass. The reflection plate 6 includes a base material 18 made of a synthetic resin film or a metal plate, and a reflection layer 19 made of aluminum or silver thin film deposited thereon.

  Light emitted from the light source 7 is introduced into the light guide plate 5 from the side surface of the light guide plate 5. The light introduced in the light guide plate 5 is totally reflected and reaches the side surface opposite to the light source 7. The pattern 14 composed of unevenness or grooves is rougher as it is closer to the light source 7 and denser as it is farther away. This is to make the intensity distribution of the light emitted upward uniform. This will be described with reference to FIG. When the totally reflected light 17 totally reflected inside the light guide plate 5 reaches the V-shaped groove 15 formed on the lower surface of the light guide plate 5, the angle of entry of the total reflected light 17 with respect to the inclined surface of the V-shaped groove 15. Does not satisfy the total reflection condition, the light can be emitted downward from the light guide plate 5. The emitted light is reflected by the inclined surface 16 of the reflecting plate 6, passes through the light guide plate 5, and is emitted as incident light Lin incident on the liquid crystal panel 4. A reflective film may be formed on the back surface of the light guide plate 5 instead of the reflective plate 6. Moreover, the shape of the groove | channel or the unevenness | corrugation formed in the lower surface of the light-guide plate 5, and arrangement | positioning of the pattern 14 are not limited to what was shown in FIG. In short, as will be described later, it is only necessary to irradiate incident light with a full angle at half maximum within approximately 20 ° with respect to a specific direction on the surface of the liquid crystal panel 4.

  FIG. 3 is an explanatory diagram for explaining the full width at half maximum of incident light incident on the liquid crystal cell 3 of the liquid crystal display device according to the present invention. FIG. 3A is a perspective view showing the relationship between the direction of the liquid crystal cell 3 and the incident light Lin, and FIG. 3B is an example of the light intensity characteristic of the incident light Lin in the 9 o'clock to 3 o'clock direction. FIG. 3C is a graph showing an example of the light intensity characteristic of the incident light Lin in the 12 o'clock to 6 o'clock direction. The same reference numerals are given to the same parts or parts representing the same functions. In addition, each graph of FIG.3 (b) and FIG.3 (c) is the actual value measured using the illuminating device 8 shown in the said FIG.2 (b).

  FIG. 3A is a perspective view of the liquid crystal cell 3 as viewed from the lighting device side. The directions on the surface of the liquid crystal cell 3 are defined as a 9 o'clock-3 o'clock direction and a 12 o'clock-6 o'clock direction. In the liquid crystal panel 4 using the TN mode in which the molecular orientation of the liquid crystal layer is twisted by 90 °, the STN mode in which the twist of 180 ° to 270 ° is twisted, or the vertical orientation mode, the polarization axis of the incident side polarizing plate 2p and the outgoing side polarizing plate 2a The polarization axis is normally in the 7: 30-1: 30 or 10: 30-4: 30 direction. The viewing angle characteristics of the liquid crystal panel 4 are the narrowest in the 9 o'clock to 3 o'clock direction and the widest in the 12 o'clock to 6 o'clock direction. That is, the display contrast decreases when viewed from an angle of 9 o'clock to 3 o'clock, but when viewed from an angle of 12 o'clock to 6 o'clock, the display contrast does not decrease and a relatively high contrast is obtained.

  FIG. 3B shows the intensity distribution of incident light incident on the liquid crystal cell 3 in the 9 o'clock to 3 o'clock direction. The horizontal axis represents the viewing angle θ (angle: °) with respect to the normal on the surface of the liquid crystal cell 3, and the vertical axis represents the brightness of incident light (incident light intensity: arbitrary unit). That is, the intensity distribution of incident light incident on the liquid crystal cell 3 when the direction in which the viewing angle characteristic of the liquid crystal panel 4 is the narrowest is defined as a specific direction is shown. Here, the full width at half maximum is defined as a viewing angle width θw at which the incident light intensity becomes ½ with respect to the maximum value of the incident light intensity. In FIG. 3B, the full width at half maximum θw is about 16 °. According to the experiment by the present inventor, the light leakage in the oblique direction due to the oblique incident light is observed by setting the full width at half maximum to about 20 ° or less by setting the direction where the viewing angle characteristic of the liquid crystal panel 4 is the narrowest as the specific direction It was found that it can be prevented from reaching the person.

  FIG. 3C shows the intensity distribution of incident light incident on the liquid crystal cell 3 in the 12 o'clock to 6 o'clock direction. The horizontal axis represents the viewing angle θ (angle: °) with respect to the normal on the surface of the liquid crystal cell 3, and the vertical axis represents the brightness of incident light (incident light intensity: arbitrary unit). That is, the viewing angle characteristic of the liquid crystal panel 4 is the widest direction. From the graph of FIG. 3C, the full width at half maximum θw is about 18 °. In the present embodiment, the full width at half maximum θw is within 20 ° even in the 12: 00-6 o'clock direction, but the full width at half maximum is not necessarily 20 ° or less for the direction in which the viewing angle of the liquid crystal panel 4 is the widest. Since the contrast in the widest viewing angle direction of the liquid crystal panel 4 is high, there is little light leakage in the oblique direction. Therefore, with respect to the direction in which the viewing angle of the liquid crystal panel 4 is the widest, for example, the full width at half maximum of the incident light Lin incident on the liquid crystal cell 3 can be set to 30 ° to 40 °. In short, the full width at half maximum of the incident light incident on the liquid crystal cell 3 may be within about 20 ° with respect to a specific direction on the surface of the liquid crystal cell 3 (for example, the direction in which the viewing angle characteristic of the liquid crystal panel 4 is the narrowest).

<Example 2>
FIG. 4 schematically shows a cross-sectional configuration of the liquid crystal display device 20 of the present embodiment. This embodiment is a liquid crystal display device capable of color display. The same parts as those in the first embodiment or the parts having the same functions are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  As shown, the phosphor plate 1 includes a red phosphor layer R that emits red light when excited by blue light, a green phosphor layer G that emits green light when excited by blue light, and an incident blue color. A blue scattering layer B that scatters light is provided. A liquid crystal cell 3 is provided between the incident side polarizing plate 2p and the outgoing side polarizing plate 2a to constitute the liquid crystal panel 4. The liquid crystal cell 3 has a configuration in which a liquid crystal layer 22 is provided in a gap between an upper substrate 25 and a lower substrate 24 made of glass, and an upper transparent electrode 21 and a lower transparent electrode 23 are formed on the inner surfaces of these substrates. . An alignment film (not shown) is formed on the transparent electrodes 21 and 23.

  In the present embodiment, the phosphor plate 1 is divided for each emission color, and is arranged so as to overlap each of the divided lower transparent electrodes DR, DG, and DB. In the case where the liquid crystal panel 4 is an active matrix type liquid crystal panel using TFTs, TFTs are connected to the transparent electrodes DR, DG, and DB to constitute unit pixels. One pixel is constituted by three unit pixels of the transparent electrodes DR, DG, and DB. When the liquid crystal panel 4 is a simple matrix type liquid crystal panel, these transparent electrodes DR, DG, DB extend in a stripe shape in a direction perpendicular to the paper surface, and the upper transparent electrode 21 on the upper substrate 25 is also divided into a large number of paper surfaces. Extending in the direction. Each intersection of the upper transparent electrode 21 and the lower transparent electrode 23 is a unit pixel.

  For example, when a lighting voltage is applied between the upper transparent electrode 21 and the transparent electrode DG and no lighting voltage is applied to the pixels in other regions, the emission side polarizing plate 2a corresponds to the transparent electrode DG. The transmitted light 12 is irradiated to the green phosphor layer G in the region to be processed. As a result, the green phosphor layer G is excited and emits green light. In the areas of the transparent electrodes DR and DB other than the transparent electrode DG, the incident light Lin is blocked by the output-side polarizing plate 2a, and the light does not enter the red phosphor layer and the blue scattering layer, and thus is not emitted or scattered. Here, the incident light Lin emitted from the illumination device 8 and entering the liquid crystal cell 3 has directivity. That is, the full width at half maximum of the incident light Lin incident on the liquid crystal cell 3 is within approximately 20 ° with respect to a specific direction on the surface of the liquid crystal cell 3 (for example, the 9 o'clock to 3 o'clock direction where the viewing angle characteristic of the liquid crystal panel 4 is the narrowest). It is. Therefore, the intensity of the obliquely incident light Lin that is incident at a deeper angle than the full angle half maximum θw in the direction in which the viewing angle characteristic of the liquid crystal panel 4 is the narrowest, for example, the 9 o'clock to 3 o'clock direction, extremely decreases. Thereby, the light leaking from the output side polarizing plate 2a is reduced, and the contrast ratio can be increased.

  It is necessary to prevent the transmitted light 12 that has passed through the transparent electrodes DR, DG, and DB from leaking into the phosphor layer adjacent to the electrodes. For this purpose, it is preferable that the incident light Lin incident on the liquid crystal cell 3 has high directivity. Therefore, it is preferable to set the full width at half maximum θw to about 20 ° or less even with respect to the incident light Lin having the highest viewing angle characteristic of the liquid crystal panel 4, for example, incident in the 12 o'clock to 6 o'clock direction.

  The light source 7 is a blue light LED. Since the wavelength band of the blue light LED is narrow, wavelength dispersion is suppressed in the liquid crystal layer 22. For this reason, the light leaking from the output side polarizing plate 2a can be reduced, which is a factor for improving the contrast.

  In the above description, instead of the blue light LED of the light source 7, an ultraviolet light LED that emits near ultraviolet light is used, and the blue phosphor layer that emits blue light by exciting the blue scattering layer B with ultraviolet light; can do. Since usable phosphor materials have already been described in the first embodiment, description thereof is omitted here.

<Example 3>
In this embodiment, a liquid crystal display device capable of input by adding a touch panel will be described. FIG. 5A is a cross-sectional view schematically showing the liquid crystal display device of this embodiment, and FIG. 5B is a schematic cross-sectional view of the touch panel. In FIG. 5A, the phosphor plate 1 is provided on the back side of the touch panel 31. Here, the phosphor plate 1 may be configured to be disposed between the touch panel 31 and the emission-side polarizing plate 2a. Since other configurations are the same as those of the first embodiment, the description thereof will be omitted as appropriate. Moreover, the same code | symbol was attached | subjected to the part which has the same part or the same function.

  The touch panel 31 is a panel having a function of detecting the touched position by touching the surface of the touch panel with a finger or an object and inputting data. FIG. 5B schematically shows a cross section of the capacitive touch panel 31. From the upper surface of the touch panel 31, a surface overcoat 32, which is a touch surface, a surface transparent electrode 34, a peripheral electrode 33, an undercoat 35, a glass substrate 36, an undercoat 35, and a back surface which are connected to and formed on the surface transparent electrode 34. A transparent electrode 37, a back surface overcoat 38, a peripheral electrode 39 that is electrically connected to the back surface transparent electrode 37, and the like are integrally configured. By touching the surface overcoat 32 which is a touch surface, the capacitance at the touched point changes, and a minute current flows through the surface transparent electrode 34 around the point. This minute current is detected at a plurality of locations by the peripheral electrode 33 formed in the periphery. The position touched by a detection circuit (not shown) is specified from the magnitude of the minute current detected at a plurality of locations. Note that the touch panel 31 is not limited to the capacitive method, and a resistive film method, an infrared method, an ultrasonic method, or the like can be used.

  Here, usually, a specific position on the screen is recognized while looking at characters, figures, and the like displayed on the display surface of the liquid crystal display device, and touches the touch panel 31 at that position to input data and the like. Therefore, it is desirable that the display position of the display information matches the position input to the touch panel 31. However, in the conventional liquid crystal display device with a touch panel, there is a distance between the display surface displayed on the liquid crystal and the input surface of the touch panel, and a positional shift occurs. Usually, the display surface of the liquid crystal panel is the position of the liquid crystal layer. Between the position of the liquid crystal layer and the surface overcoat 32 which is the touch surface of the touch panel 31, one transparent substrate of the liquid crystal cell, the emission side polarizing plate 2a, and the glass substrate 36 of the touch panel are interposed. As a result, a displacement between the display surface and the touch surface occurred.

  However, in the third embodiment, the phosphor plate 1 that is the display surface is positioned in the vicinity of the surface overcoat 32 that is the touch surface of the touch panel 31. Therefore, there is an advantage that there is almost no displacement between the touch surface and the display surface. In addition, the touch panel 31 can be installed under the phosphor plate 1 which is a display surface. Also in this case, since the touch surface and the display surface are only via the glass substrate 36 of the touch panel 31, the positional deviation between the display surface and the touch surface is not a problem.

<Example 4>
FIG. 6 is a cross-sectional view schematically showing the liquid crystal display device 40 of this embodiment. In this embodiment, the reflective polarizing plate 41 is used as the outgoing side polarizing plate. Other configurations are the same as those in the first embodiment. The same portions or portions having the same function are denoted by the same reference numerals, and repeated description is omitted as appropriate.

  The reflective polarizing plate 41 transmits light in the direction of the polarization axis and reflects light in a direction orthogonal to the polarization axis. The transmitted light 12 that has entered the phosphor plate 1 after passing through the reflective polarizing plate 41 excites the phosphor of the phosphor plate 1 and emits light. The emitted light is emitted as display light 11 in front of the display surface, and is emitted as backward light emission 42 also behind the display surface. However, by using the reflective polarizing plate 41 as the output side polarizing plate, the rear emission 42 having a polarization direction orthogonal to the polarization axis of the reflective polarizing plate 41 is reflected. The reflected light 43 can be emitted to the front of the display surface by selecting the phosphor material and thickness of the phosphor plate 1. Furthermore, the display light 11 and the reflected light 43 can be overlapped by bringing the phosphor plate 1 and the reflective polarizing plate 41 close to each other. Thereby, the brightness | luminance of the display light 11 can be made higher. In FIG. 6, the phosphor plate 1 and the reflective polarizing plate 41 are separated from each other for easy understanding, but the reflective polarizing plate 41 and the phosphor plate 1 are preferably formed in contact with each other.

1 is a schematic cross-sectional view of a liquid crystal display device according to the present invention. It is explanatory drawing of the illuminating device used for the liquid crystal display device which concerns on this invention. It is a figure for demonstrating the full width at half maximum of the incident light which injects into the liquid crystal cell of the liquid crystal display device which concerns on this invention. 1 is a schematic cross-sectional view of a liquid crystal display device according to the present invention. 1 is a schematic cross-sectional view of a liquid crystal display device according to the present invention. 1 is a schematic cross-sectional view of a liquid crystal display device according to the present invention. It is sectional drawing of a conventionally well-known liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Phosphor plate 2a Outgoing side polarizing plate 2p Incident side polarizing plate 3 Liquid crystal cell 4 Liquid crystal panel 5 Light guide plate 6 Reflecting plate 7 Light source 8 Illuminating device 9 Emission light 10, 20, 30, 40 Liquid crystal display device 11 Display light 12 Transmitted light 13 Vertical direction 14 Pattern 15 V-shaped groove

Claims (6)

A liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes formed on the inner surface, an illumination device that irradiates light to the liquid crystal cell, and an incident side disposed between the liquid crystal cell and the illumination device A polarizing plate, an output-side polarizing plate disposed on the liquid crystal cell opposite to the illumination device, and provided above the output-side polarizing plate and excited by light emitted from the illumination device. A phosphor that emits light,
A liquid crystal display device wherein a full width at half maximum of incident light emitted from the illumination device and incident on the liquid crystal cell is within about 20 ° with respect to a specific direction on the surface of the liquid crystal cell.   The liquid crystal display device according to claim 1, wherein light emitted from the illumination device is blue light.   The liquid crystal display device according to claim 1, wherein a touch panel is disposed above the emission side polarizing plate.   The liquid crystal display device according to claim 3, wherein the phosphor is formed on a surface of the touch panel.   The liquid crystal display device according to claim 1, wherein the output side polarizing plate is a reflective polarizing plate.   The liquid crystal display device according to claim 1, wherein the phosphor has a configuration in which a plurality of types of phosphors having different emission colors are arranged.

Images