JP2012078494A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform reflective display and transmission display without discriminating the respective pixels of a liquid crystal display panel into a reflective display part and a transmission display part, and to obtain high display fidelity.SOLUTION: A dielectric layer 50 is configured such that transparent first dielectric film and second dielectric film having mutually different refractivity are alternately laminated between a liquid crystal display panel 1and a backlight 30, and that the rays of light made incident from a direction crossing the film surface of each dielectric film are reflected and transmitted by prescribed reflectivity and transmissivity.

Description

  The present invention relates to a reflection / transmission type liquid crystal display device.

  As the liquid crystal display device, the outside light that is the light of the usage environment is used, the light that is incident from the front of the liquid crystal display panel and reflected through the liquid crystal layer is reflected, is transmitted through the liquid crystal layer again, and is emitted to the front of the liquid crystal display panel The reflected light to be displayed and the illumination light from the backlight arranged behind the liquid crystal display panel are used, and the light incident on the liquid crystal display panel from the rear and transmitted through the liquid crystal layer is emitted to the front of the liquid crystal display panel. There is a reflection / transmission type that performs both display and transmission display.

  As a reflection / transmission type liquid crystal display device, for example, there is a configuration as described in Patent Document 1. In this liquid crystal display device, each pixel of the liquid crystal display panel is divided into two regions, and incident on one of the two regions on the rear substrate of the two transparent substrates facing each other with the liquid crystal layer interposed therebetween. By providing a pixel electrode formed to reflect the reflected light and transmit the light incident on the other region, a reflective display portion and a transmissive display portion are formed for each pixel.

JP 2004-93715 A

  However, a liquid crystal display device in which each pixel of the liquid crystal display panel is divided into a reflective display portion and a transmissive display portion halves the display area that can be used for reflective display and the display area that can be used for transmissive display. In this case, the utilization factor of light incident from the front and the utilization factor of irradiation light from the backlight in the transmissive display are also halved. For this reason, in the liquid crystal display device, the reflective display and the transmissive display are both dark and the display quality is deteriorated.

  The present invention provides a liquid crystal display device that can perform reflective display and transmissive display without dividing each pixel of a liquid crystal display panel into a reflective display portion and a transmissive display portion, and can obtain high display quality. It is intended to do.

The liquid crystal display device according to claim 1,
A liquid crystal layer sealed between the front substrate and the rear substrate disposed opposite to each other, a front polarizing plate disposed on the outer surface of the front substrate, and a rear polarizing plate disposed on the outer surface of the rear substrate, A liquid crystal display panel for performing display by controlling the light transmittance of each pixel by applying a voltage to the liquid crystal layer;
A backlight that is arranged behind the liquid crystal display panel and that irradiates illumination light toward the liquid crystal display panel from an irradiation surface facing the liquid crystal display panel;
A dielectric layer disposed between the liquid crystal display panel and the backlight;
With
The dielectric layer is formed by alternately laminating transparent first dielectric films and second dielectric films having different refractive indexes, and passes through the liquid crystal display panel toward the dielectric layer. It is characterized in that a part of outside light is reflected and the other part is transmitted.

The invention according to claim 2 is the liquid crystal display device according to claim 1, wherein the first dielectric film is Nb ₂ O ₅ or TiO ₂ , and the second dielectric film is SiO ₂ . It is characterized by being.

  According to a third aspect of the present invention, in the liquid crystal display device according to the second aspect, the average reflectance for each wavelength light in the visible light band of the dielectric layer is 55 to 60%. .

  According to a fourth aspect of the present invention, in the liquid crystal display device according to the second aspect of the present invention, the average transmittance for each wavelength light in the visible light band of the dielectric layer is 40 to 45%.

  The invention according to claim 5 is the liquid crystal display device according to claim 3 or 4, wherein the dielectric layer has a total value of 99% of the average reflectance and the average transmittance for each wavelength light in the visible light band. It has the characteristics described above.

  According to a sixth aspect of the present invention, in the liquid crystal display device according to any one of the first to fifth aspects, the dielectric layer is formed on a transparent base film, and the liquid crystal display panel and the back surface are formed. It is arranged between the lights.

  The invention according to claim 7 is the liquid crystal display device according to any one of claims 1 to 6, wherein the dielectric layer is on a CIE chromaticity diagram of reflected light when white light is incident. X coordinates and y coordinates of the white point in the range of x = 0.315 to 0.32 and y = 0.315 to 0.32, the x coordinate of the white point on the CIE chromaticity diagram of the transmitted light The value and the y coordinate value have spectral characteristics in the range of x = 0.30 to 0.305 and y = 0.315 to 0.32.

  According to an eighth aspect of the present invention, in the liquid crystal display device according to any one of the first to seventh aspects, the backlight transmits light incident from an illumination surface side of the illumination light to the liquid crystal display panel. It has a function of reflecting toward it.

The invention according to claim 9 is the liquid crystal display device according to claim 8,
The backlight is
An incident surface that is made of a plate-shaped transparent member is formed to allow light to be incident on at least one end surface, and an exit surface that emits light incident from the incident surface is formed on one of the two plate surfaces. A light guide plate formed with a reflection surface that internally reflects light incident from the incident surface toward the emission surface;
A reflector disposed to face the reflecting surface of the light guide plate;
A light emitting element disposed to face the incident surface of the light guide plate;
A plurality of prism portions are formed on one surface of the transparent sheet-like member, and a prism array disposed on the emission surface of the light guide plate;
With
The surface on which the prism array is disposed is disposed to face the dielectric layer.

  According to a tenth aspect of the present invention, in the liquid crystal display device according to any one of the first to ninth aspects, the liquid crystal display panel and the dielectric layer, or the dielectric layer and the backlight. A reflective polarizer that has a transmission axis and a reflection axis in a direction perpendicular to each other, transmits light of a polarization component parallel to the transmission axis, and reflects light of a polarization component parallel to the reflection axis It is arranged.

  According to an eleventh aspect of the present invention, in the liquid crystal display device according to any one of the first to tenth aspects, the dielectric layer is formed on an outer surface of the rear polarizing plate of the liquid crystal display panel. It is characterized by.

  The invention according to claim 12 is the liquid crystal display device according to claim 10, wherein the dielectric layer is formed on a surface of the reflective polarizing plate facing the backlight. .

  According to a thirteenth aspect of the present invention, in the liquid crystal display device according to the ninth aspect, the backlight includes a diffusion sheet disposed on the prism array, and the dielectric layer includes the diffusion layer. It is formed on a sheet.

  The invention described in claim 14 is the liquid crystal display device according to any one of claims 1 to 13, wherein the liquid crystal display panel is an active matrix liquid crystal display panel using a thin film transistor as a switching element. A plurality of thin film transistors connected to scanning signal lines and data signal lines and a plurality of pixel electrodes respectively connected to the thin film transistors are provided on a surface of the substrate facing the front substrate, and the rear substrate of the front substrate And a common electrode facing each of the pixel electrodes is provided on the surface facing each other.

  According to a fifteenth aspect of the present invention, in the liquid crystal display device according to the fourteenth aspect, the liquid crystal display panel includes a liquid crystal layer made of nematic liquid crystal having negative dielectric anisotropy, and the liquid crystal molecules are arranged in the front direction. The liquid crystal display panel is characterized in that it is a vertical alignment type liquid crystal display panel aligned perpendicularly to the plate surfaces of the substrate and the rear substrate.

  According to a sixteenth aspect of the present invention, in the liquid crystal display device according to the fourteenth aspect, the liquid crystal display panel has a liquid crystal layer made of a nematic liquid crystal having a positive dielectric anisotropy, and the liquid crystal molecules It is a TN type liquid crystal display panel that is twist-oriented between the substrate and the rear substrate.

  The invention according to claim 17 is the liquid crystal display device according to any one of claims 1 to 16, wherein the liquid crystal display panel is arranged between the front substrate and the front polarizing plate. And a second λ / 4 retardation plate disposed between the rear substrate and the rear polarizing plate.

  According to the liquid crystal display device of the present invention, it is possible to perform reflective display and transmissive display without dividing each pixel of the liquid crystal display panel into a reflective display portion and a transmissive display portion, and to obtain high display quality. it can.

The disassembled perspective view of the liquid crystal display device of a 1st Example. The side view of the said liquid crystal display device. The top view of a part of back board | substrate of the said liquid crystal display panel. FIG. 4 is an enlarged cross-sectional view of a part of the liquid crystal display panel taken along the line IV-IV in FIG. 3. The figure which shows the orientation state of the liquid crystal molecule at the time of the voltage application in the said liquid crystal display panel. The enlarged side view of a part of light-guide plate which comprises a backlight. The expanded sectional view of the light emitting element which comprises the said backlight. The expanded sectional view of a part of dielectric layer. FIG. 6 is a reflection / transmission characteristic diagram of the dielectric layer and a transflective film made of a silver thin film. The figure which shows the white point on the CIE chromaticity diagram of the reflected light and the transmitted light by the said dielectric material layer. The enlarged part of the XI part of FIG. The schematic diagram of the reflective display and transmissive display by the said liquid crystal display device. The schematic diagram of the light reflection by the said backlight. The disassembled perspective view of the liquid crystal display device of a 2nd Example. The schematic diagram of the reflective display and transmissive display by the liquid crystal display device of a 2nd Example. The disassembled perspective view of the liquid crystal display device of a 3rd Example. The disassembled perspective view of the liquid crystal display device of 4th Example. The disassembled perspective view of the liquid crystal display device of 5th Example. The disassembled perspective view of the liquid crystal display device of 6th Example. The disassembled perspective view of the liquid crystal display device of 7th Example.

[First embodiment]
As shown in FIGS. 1 and 2, the liquid crystal display device according to the first embodiment of the present invention is arranged in a vertical alignment type liquid crystal display panel 1 _(VA) and behind the liquid crystal display panel 1 _(VA) . A backlight 30 and a dielectric layer 50 disposed between the liquid crystal display panel 1 and the backlight 30 are provided.

As shown in FIGS. 3 and 4, the liquid crystal display panel 1 _(VA) includes a transparent front substrate 2 and a rear substrate 3 that are arranged to face each other with a predetermined gap, and between the front substrate 2 and the rear substrate 3. A sealed liquid crystal layer 23, a front polarizing plate 25 disposed on the outer surface of the front substrate 2, and a rear polarizing plate 26 disposed on the outer surface of the rear substrate 3 are provided.

The liquid crystal display panel 1 _(VA) is an active matrix liquid crystal display panel using thin film transistors (hereinafter referred to as TFTs) as switching elements, and is a surface facing the front substrate 2 of the rear substrate 3 (hereinafter referred to as the inner surface of the rear substrate 3). A plurality of scanning signal lines 4 formed so as to be parallel to each other in a predetermined direction (left and right direction in FIG. 3), and in a direction orthogonal to the extending direction of the scanning signal lines 4 A plurality of data signal lines 5 formed by stretching, a plurality of TFTs 6 arranged so as to correspond to the intersections of the scanning signal lines 4 and the data signal lines 5, and formed corresponding to the respective TFTs 6 A plurality of pixel electrodes 12 made of a transparent conductive film such as an ITO film are provided.

  The TFT 6 includes a gate electrode 7 formed on the rear substrate 3, a transparent gate insulating film 8 that covers the gate electrode 7 and is formed on the entire area of the rear substrate 3, and a gate electrode 7 on the gate insulating film 8. And a contact layer (not shown) made of n-type amorphous silicon on one side and the other side sandwiching the channel region of the semiconductor thin film 9, respectively. It comprises a source electrode 10 and a drain electrode 11 formed via the electrode.

  The gate electrode 7 of the TFT 6 is connected to the scanning signal line 4 corresponding to the TFT 6, and the source electrode 10 is connected to the data signal line 5 corresponding to the TFT 6. The scanning signal line 4 is formed on the rear substrate 3, and the gate electrode 7 of the TFT 6 is formed integrally with the scanning signal line 4. The data signal line 5 is formed on the gate insulating film 8, and the source electrode 10 of the TFT 6 is formed integrally with the data signal line 5.

  The pixel electrode 12 is disposed on the gate insulating film 8. The pixel electrode 12 has a size such that each side does not overlap the scanning signal line 4 and the data signal line 5 in a region surrounded by the adjacent scanning signal lines 4 and 4 and the adjacent data signal lines 5 and 5. And is connected to the drain electrode 11 of the TFT 6 at one corner.

  Further, a capacitance that forms a compensation capacitor having the gate insulating film 8 as a dielectric layer between the pixel electrode 12 and the side surface of each pixel electrode 12 through the gate insulating film 8 on the inner surface of the rear substrate 3. An electrode 15 is provided.

  The capacitor electrode 15 is formed in a frame shape so as to overlap the side part of the entire circumference of the pixel electrode 12 except for the part where the TFT 6 is connected. Each capacitor electrode 15 has a row of portions facing each other on the side opposite to the side where the TFT 6 of the pixel electrode 12 is connected (side parallel to the extending direction of the scanning signal line 4). It is commonly connected by forming.

  Further, a transparent overcoat insulating film 16 is formed on the rear substrate 3 so as to cover the TFTs 6 and the data signal lines 5, and a first vertical alignment film 17 is formed on the overcoat insulating film 16. Has been. In FIG. 3, the overcoat insulating film 16 and the first vertical alignment film 17 are omitted.

  On the other hand, on the surface facing the rear substrate 3 of the front substrate 2 (hereinafter referred to as the inner surface of the front substrate 2), the wiring regions of the scanning signal lines 4 and the data signal lines 5 and the arrangement regions of the TFTs 6 are covered. The light-shielding film 18 formed in the above is provided. Further, on the inner surface of the front substrate 2, a color filter composed of a red filter 19R, a green filter 19G, and a blue filter 19B formed in a shape corresponding to each pixel electrode 12 is provided.

  Further, a common electrode 20 made of a transparent conductive film such as an ITO film formed over the entire inner surface of the front substrate 2 on the color filter is provided on the inner surface of the front substrate 2 so as to face each pixel electrode 12. A second vertical alignment film 21 is formed on the common electrode 20.

  The front substrate 2 and the rear substrate 3 are bonded to each other via a frame-shaped sealing material 22 (see FIGS. 1 and 2) surrounding a screen area where the pixel electrodes 12 are arranged. A liquid crystal layer 23 made of nematic liquid crystal having negative dielectric anisotropy is sealed in a gap surrounded by the sealing material 22 between the front substrate 2 and the rear substrate 3.

  The liquid crystal molecules 23a of the liquid crystal layer 23 are in the state of no electric field where no voltage is applied between the pixel electrode 12 and the common electrode 20, as shown in FIG. Oriented perpendicular to the planes of the substrates 2 and 3. Further, when a voltage is applied between the pixel electrode 12 and the common electrode 20, the liquid crystal molecules 23 a fall from each side of the pixel electrode 12 toward the center of the pixel electrode 12, and are oriented radially from the center of the pixel electrode 12. To do.

  However, in this embodiment, since the pixel electrode 12 is formed in a vertically long rectangular shape with a ratio of the vertical width to the horizontal width of about 3: 1, the radial alignment of the liquid crystal molecules 23a when a voltage is applied is disturbed. May occur.

  Therefore, in this embodiment, the pixel electrode 12 is provided with two slits 13 so that the vertical width of the pixel electrode 12 is divided into three equal parts, so that the pixel electrode 12 is divided into three electrode portions 12a, 12b and 12c. The slit 13 is formed leaving the connecting portions 14 between the electrode portions 12a and 12b and the portions 12b and 12c separated by the slit 13, and accordingly, the pixel electrode 12 from the data signal line 5 through the TFT 6 is formed. The data signal applied to is applied to all of the electrode portions 12a, 12b, 12c.

  As described above, when the pixel electrode 12 is divided into substantially square electrode portions 12a, 12b, and 12c, the liquid crystal molecules 23a are separated from each side of the electrode portion for each region corresponding to the electrode portions 12a, 12b, and 12c. It falls down toward the center of an electrode part, and it orientates radially for every area | region like FIG.

  Further, as shown in FIG. 1, the rear substrate 3 has a driver mounting portion 3 a that projects from the front substrate 2, and a plurality of scanning signal lines 4 and data signal lines provided on the inner surface of the rear substrate 3. 5 is connected to the display driver 24 mounted on the driver mounting section 3a.

  Although omitted in FIG. 1, the driver mounting portion 3a is provided with a plurality of control circuit connection terminals for connecting the display driver 24 to a control circuit (not shown) and a common electrode terminal. The common electrode 20 is connected to the common electrode terminal through a cross connection portion formed in the substrate bonding portion by the sealing material 22. The capacitor electrode 15 is connected to the common electrode terminal together with the common electrode 20.

  The display driver 24 is composed of an LSI chip, and applies a scanning signal for turning on the TFT 6 in a predetermined cycle to each scanning signal line 4 based on display data and a synchronization signal supplied from the control circuit. A data signal having a voltage value corresponding to the gradation value of the display data is applied to the data signal line 5.

  The front polarizing plate 25 and the rear polarizing plate 26 are absorption polarizing plates, and have polarization axes 25a and 26a and an absorption axis (not shown) in directions orthogonal to each other and are polarized parallel to the transmission axes 25a and 26a. The light of the component is transmitted, and the light of the polarization component parallel to the absorption axis is absorbed. As shown in FIG. 1, the front polarizing plate 25 and the rear polarizing plate 26 are arranged with their transmission axes 25a and 26a orthogonal to each other. The front polarizing plate 25 is preferably an anti-glare polarizing plate whose outer surface is subjected to an external light antireflection treatment.

Further, the liquid crystal display panel 1 _(VA) includes first and second λ / 4 retardation plates 27 and 28 that give a quarter-wave phase difference between ordinary light and abnormal light of transmitted light. . The first λ / 4 retardation plate 27 has a slow axis 27 a of the λ / 4 retardation plate 27 between the front substrate 2 and the front polarizing plate 25 with respect to the transmission axis 25 a of the front polarizing plate 25. It is arranged to cross diagonally at an angle of 45 °. Further, the second λ / 4 retardation plate 28 passes through the slow axis 28 a of the λ / 4 retardation plate 28 between the rear substrate 3 and the rear polarizing plate 26, and is transmitted through the rear polarizing plate 26. The shaft 26a is obliquely intersected at an angle of 45 ° and is disposed perpendicular to the slow axis 27a of the first λ / 4 phase difference plate 27.

The liquid crystal display panel 1 _(VA) includes a diffusion adhesive material layer 29 disposed between the front substrate 2 and the first λ / 4 retardation plate 27. The diffusion adhesive material layer 29 is obtained by dispersing light diffusion particles in a transparent adhesive material, and has a diffusibility with a haze value of 45 to 83%.

  The first λ / 4 retardation plate 27 is attached to the outer surface of the front substrate 2 via the diffusion adhesive layer 29, and the front polarizing plate 25 is attached to the outer surface of the first λ / 4 retardation plate 27. It is attached. The second λ / 4 retardation plate 28 is attached to the outer surface of the rear substrate 3, and the rear polarizing plate 26 is attached to the outer surface of the second λ / 4 retardation plate 28.

In the liquid crystal display panel 1 _(VA) , the light transmittance of each pixel provided with the TFT 6 and the pixel electrode 12 is applied to the liquid crystal layer 23 by applying a voltage to the liquid crystal layer 23, that is, between the pixel electrode 12 and the common electrode 20. The display is controlled by the tilted orientation of the liquid crystal molecules 23a by the application of voltage.

Next, the backlight 30 will be described. As shown in FIGS. 1 and 2, the backlight 30 is made of a transparent material having a rectangular plate shape corresponding to the entire screen area of the liquid crystal display panel 1 _(VA) , and has at least one end surface (in this embodiment, a rectangular plate). Is formed on one of the two plate surfaces, and a flat emission surface 33 for emitting the light incident from the incident surface 32 is formed on the other plate surface. A light guide plate 31 formed with a reflection surface 34 that reflects light incident from the incident surface 32 toward the output surface 33 on the surface, and a reflection plate 35 disposed to face the reflection surface 34 of the light guide plate 31. And a plurality of light emitting elements 36 arranged to face the incident surface 32 of the light guide plate 31.

  As shown in FIG. 6, the light guide plate 31 has a reflective surface 34 in the direction of the outer surface of the reflective surface 34 from the end side where the incident surface 32 of the light guide plate 31 is formed toward the other end side. A gentle inclined surface 34a inclined at an angle of about 5 to 15 ° with respect to the normal direction of the emission surface 33 of 31 and 45 to 45 with respect to the normal direction in a direction opposite to the inclination direction of the gentle inclined surface 34a. A cross-sectional shape in which steeply inclined surfaces 34b inclined at an angle of about 70 ° are alternately formed is a sawtooth surface.

  The light guide plate 31 emits the light emitted from the light emitting element 36 and incident on the light guide plate 31 from the incident surface 32, as shown by the arrow in FIG. 6, with the light emitting plate 33 and the gently inclined surface 34 a of the reflecting surface 34. The light is guided through the light guide plate 31 in the longitudinal direction while being reflected, and is internally reflected by the steeply inclined surface 34b of the reflecting surface 34, and is incident on the exit surface 33 at an angle smaller than the total reflection angle (without being internally reflected). The light transmitted through the emission surface 33 is emitted from the emission surface 33.

  The light guided through the light guide plate 31 includes light that passes through the reflecting surface 34 and leaks to the outside. However, this leaked light is reflected by the reflective plate 35 and returned to the light guide plate 31 again. The light exits from the exit surface 33.

  Further, the light emitting element 36 disposed to face the incident surface 32 of the light guide plate 31 is a solid light emitting element using an LED (light emitting diode), and performs transmissive display using illumination light from the backlight 30. Is lit.

  In this embodiment, as the light emitting element 36, a blue LED 38 is arranged at the center of the inner bottom surface of a box-shaped housing 37 having one surface made of a resin molded product as shown in FIG. Further, a material in which a transparent material 40 such as a transparent resin is filled with a fluorescent layer 39 in which particulate red fluorescent material 41 and green fluorescent material 42 are dispersed at a predetermined ratio is used.

  The light emitting element 36 generates pseudo white light that is very close to white light by an additive color mixture of blue light emitted from the blue LED 38 and red fluorescence and green fluorescence emitted from the red fluorescent material 41 and the green fluorescent material 42 of the fluorescent layer 39. Exit.

  Further, as shown in FIGS. 1 and 2, the backlight 30 includes first and second prism arrays 43 and 44 that are arranged in order on the light emission surface 33 of the light guide plate 31. In the prism arrays 43 and 44, a plurality of prism portions 43a and 44a are formed on one surface of a transparent sheet member made of acrylic resin or the like.

  And each prism part 43a of the 1st prism array 43 arrange | positioned at the light-guide plate 31 side is made into the shape extended | stretched linearly in the predetermined direction, for example, the direction parallel to a pair of side which the prism array 43 opposes. Is formed. Further, each prism portion 44 a of the second prism array 44 is formed in a linearly extending shape that is orthogonal to the extending direction of the prism portion 43 a of the first prism array 43.

  Note that the prism portions 43a and 44a of the first and second prism arrays 43 and 44 are respectively methods of surfaces opposite to the surfaces on which the prism portions 43a and 44a of the sheet-like member are formed (hereinafter referred to as flat surfaces). It has an isosceles triangle shape centering on the line direction, and has a cross-sectional shape in which the apex angle (intersection angle between two inclined surfaces) is in the range of 80 ° to 100 °, preferably substantially 90 °. Is preferred.

  The backlight 30 further includes a diffusion layer 45 disposed between the emission surface 33 of the light guide plate 31 and the first prism array 43. The diffusion layer 45 is made of, for example, a transparent pressure-sensitive adhesive layer in which light scattering particles are dispersed, and has a scattering characteristic with a haze value of 20 to 50%.

  The first prism array 43 is disposed with the flat surface of the prism array 43 facing the light guide plate 31, and is attached to the light output surface 33 of the light guide plate 31 via the diffusion layer 45. The second prism array 44 is disposed on the first prism array 43 with the flat surface of the prism array 44 facing the first prism array 43.

In the backlight 30, the light emitted from the light exit surface 33 of the light guide plate 31 is diffused by the diffusion layer 45, and these prism arrays 43, 44 are further formed by the first prism array 43 and the second prism array 44. By refracting in a direction in which the angle with respect to the normal direction of the flat surface becomes smaller, illumination light having a high front luminance and a uniform luminance distribution is irradiated toward the liquid crystal display panel 1 _(VA) .

In addition, the backlight 30 supplies light incident from the illumination light irradiation surface, that is, the surface facing the liquid crystal display panel 1 _(VA) (the surface on which the prism portion 44a of the second prism array 44 is formed). It has a function of reflecting toward the display panel 1 _(VA) .

That is, as shown by the arrow in FIG. 13, the second prism array 44 reflects light incident from the surface facing the liquid crystal display panel 1 _{(VA) in the} lateral direction by the inclined surface of the prism portion 44a. The reflected light is reflected toward the liquid crystal display panel 1 _(VA) by the inclined surface of the adjacent prism portion 44a. Further, the first prism array 43 reflects the light transmitted through the second prism array 44 in the same manner as the light antireflection of the second prism array 44.

The light reflected by the first prism array 43 is incident on the second prism array 43, and the light transmitted through the second prism array 44 is directed toward the liquid crystal display panel 1 _(VA) . And exit.

  Of the light reflected by the first prism array 43 and incident on the second prism array 44, the light internally reflected by each prism portion 44 a of the second prism array 44 is again the first prism array 44. Of this light, the light reflected by each prism portion 44 a of the second prism array 44 is incident on the second prism array 43 again.

Furthermore, among the light incident on the second prism array 44 from the side facing the liquid crystal display panel 1 _(VA) , the light transmitted through the second prism array 44 and the first prism array 43 is shown in FIG. As indicated by the arrows, the light reflected by the reflecting surface 34 or the reflecting plate 35 of the light guide plate 31 and transmitted through the first and second prism arrays 43 and 44 out of this light is the liquid crystal display panel 1 _{(VA )} .

Although the diffusion layer 45 is omitted in FIG. 13, the light reflected by the reflection surface 34 or the reflection plate 35 of the light guide plate 31 is diffused by the diffusion layer 45. The light transmitted through the second prism arrays 43 and 44 is emitted toward the liquid crystal display panel 1 _(VA) . Therefore, the light reflected by the backlight 30 toward the liquid crystal display panel 1 _(VA) is also light with high front luminance and uniform luminance distribution.

  Next, the dielectric layer 50 disposed between the liquid crystal display panel 1 and the backlight 30 will be described. The dielectric layer 50 is formed by alternately laminating transparent first dielectric films 51 and second dielectric films 52 having different refractive indexes as shown in FIG. The light incident from the direction intersecting the film surfaces 51 and 52 is reflected and transmitted with a predetermined reflectance and transmittance.

  The first dielectric film 51 and the second dielectric film 52 are both optically isotropic dielectric materials, and the first dielectric film 51 has a refractive index of 2.3 to 2.5. The second dielectric film 52 has a refractive index of 1.4 to 1.6.

  The dielectric layer 50 is formed by alternately stacking first dielectric films 51 and second dielectric films 52 on an optically isotropic transparent base film 53. Has been. The number of stacked first and second dielectric films 51 and 52 (the total number of the first dielectric film 51 and the second dielectric film 52) is 3 to 10 layers. The first dielectric film 51 and the second dielectric film 52 each have a thickness of about 50 nm. Therefore, the thickness of the dielectric layer 50 (thickness not including the base film 53) is 150 to It is about 500 nm.

  The dielectric layer 50 allows light incident from one surface side to pass through each dielectric by the interface between the first dielectric film 51 and the second dielectric film 52 as shown by the arrow in FIG. The light reflected by the reflectance corresponding to the difference in refractive index between the body films 51 and 52 and emitted from the one surface and transmitted through the interface between the first dielectric film 51 and the second dielectric film 52 The light exits from the other surface. Although FIG. 8 shows reflection and transmission of light incident from the side opposite to the base film 53 side, the dielectric layer 50 also reflects light incident from the base film 53 side with the same reflectance and transmittance. And make it transparent.

  The dielectric layer 50 has a characteristic that the total value of the average reflectance and the average transmittance for each wavelength light in the visible light band is 99% or more. The average reflectance and average transmittance described here are the x coordinates of the white point on the CIE chromaticity diagram of the reflected light and transmitted light when white light (measurement reference light) is incident on the dielectric layer 50. Y value obtained from the value and the y coordinate value. Specifically, x = X / (X + Y + Z), y = Y / (X + Y + Z), z = Z / (X + Y + Z) = 1−x−z (X, Y, and Z are objects by reflection in the XYZ color system) The Y value is determined by solving a relational expression of color tristimulus values, z is a value determined from x and y.

The dielectric layer 50 used in this example is a first dielectric film 51 made of Nb ₂ O ₅ (niobium oxide) having a refractive index of 2.33 or TiO ₂ (titanium oxide) having a refractive index of 2.5. And second dielectric films 52 made of SiO ₂ (silicon dioxide) having a refractive index of 1.45, and the average reflectance is in the range of 55 to 60%, the average transmittance Is in the range of 40-45%.

  Since this dielectric layer 50 has a total value of average reflectance and average transmittance of 99% or more, the light absorptance in the visible light band is 1% or less. For example, the light absorptance of the dielectric layer 50 having an average reflectance of 57.8% and an average transmittance of 41.8% is 0.4%.

  In contrast to the dielectric layer 50, a transflective film made of a silver thin film, generally called a half mirror, has a reflectance and a transmittance corresponding to the density of the silver thin film (the distribution density of the holes through which light passes). For example, the light absorptivity of the transflective film having an average reflectance of 81.0% and an average transmittance of 10.3% is 8.7%.

  As described above, the transflective film made of a silver thin film (hereinafter referred to as a silver thin film) absorbs 8.7% of incident light, but the dielectric layer 50 has a light absorption rate of 1%. Since it is the following, most of the incident light is reflected and transmitted.

  FIG. 9 shows a dielectric layer 50 having an average reflectance of 57.8% and an average transmittance of 41.8%, and a silver thin film having an average reflectance of 81.0% and an average transmittance of 10.3%. The reflection / transmission characteristics are shown. In FIG. 9, the reflectance is a regular reflectance when light is incident from a direction inclined by 5 ° in one direction with respect to the normal direction of the outer surfaces of the dielectric layer 50 and the transflective film. The transmittance is the transmittance of light incident from the normal direction.

  As shown in FIG. 9, both the silver thin film and the dielectric layer 50 have spectral characteristics that are different in reflectance and transmittance with respect to light of each wavelength. Therefore, the light reflected by the dielectric layer 50 and the light transmitted through the dielectric layer 50 are light colored with respect to the incident light. Is a very slight band color that is less than or equal to the band color of the reflected and transmitted light from the silver thin film.

  That is, as shown in FIGS. 10 and 11, the x coordinate value and the y coordinate value of the white point W1a on the CIE chromaticity diagram of the reflected light when white light is incident on the dielectric layer 50 are x = 0. It is the range of 315-0.32, y = 0.315-0.32. Further, the x coordinate value and the y coordinate value of the white point W1b on the CIE chromaticity diagram of the transmitted light are in the ranges of x = 0.30 to 0.305 and y = 0.315 to 0.32.

  On the other hand, as shown in FIG. 11, the white point on the CIE chromaticity diagram of the reflected light and transmitted light when white light is incident on the silver thin film is such that the white point W2a of the reflected light is x = 0. 310, y = about 0.322, and the white point W2b of the transmitted light is x = about 0.329, y = about 0.317.

  Thus, the amount of deviation of the white point W1a of the reflected light from the dielectric layer 50 from the achromatic point W (x = 0.310, y = 0.317) is the deviation of the white point W2a of the reflected light from the silver thin film. Less than the amount. Further, the amount of deviation of the transmitted light white point W1b from the achromatic point W by the dielectric layer 50 is only slightly larger than the amount of deviation of the transmitted light white point W2a by the silver thin film.

  Moreover, the amount of deviation of the white point W1a of the reflected light from the achromatic color point W by the dielectric layer 50 is within 0.01 for the x coordinate value and within 0.003 for the y coordinate value, and the white point W1a of the reflected light. The deviation amount from the achromatic point W is within 0.033 for the x coordinate value and within 0.003 for the y coordinate value. Therefore, the band colors of the reflected light and the transmitted light by the dielectric layer 50 are very slight band colors.

The dielectric layer 50 is disposed between the liquid crystal display panel 1 _(VA) and the backlight 30 so that the outer surface of the base film 53 of the dielectric layer 50 is opposed to the backlight 30, and the second layer of the backlight 30. Overlaid on the prism array 44. The dielectric layer 50 may be disposed by attaching the base film 53 to the rear polarizing plate 26 of the liquid crystal display panel 1 with the outer surface of the base film 53 facing the liquid crystal display panel 1 _(VA) .

  This liquid crystal display device performs reflective display using external light in an environment with sufficient illuminance, and illuminates illumination light from the backlight 30 when used in a dark environment where reflective display cannot be performed. Do. Further, when the brightness of the reflective display is insufficient, such as when used in a dim environment, the reflective display is performed by assisting the transmissive display by irradiating the backlight 30 with illumination light of relatively low brightness. Can be supplemented by transmissive display.

FIG. 12 is a schematic diagram of reflection display and transmission display by the liquid crystal display device. FIG. 12A shows light emission in the reflection display, and FIG. 12B shows light emission in the transmission display. ing. In FIGS. 12A and 12B, the diffusion adhesive layer 29 of the liquid crystal display panel 1 _(VA) , the diffusion layer 45 of the backlight 30, and the base film 53 of the dielectric layer 50 are omitted. .

First, reflective display using outside light will be described. As shown in FIG. 12A, outside light a ₀ incident from the front of the liquid crystal display panel 1 _(VA) is parallel to the absorption axis by the front polarizing plate 25. Do absorbed light polarization component becomes the transmission axis 25a parallel to linearly polarized light a _1, further first lambda / 4 is given a phase difference of a quarter wavelength by the retardation plate 27, the circularly polarized light a ₂ And enters the liquid crystal layer 23.

When a voltage lower than the voltage for tilting and aligning the liquid crystal molecules 23a between the pixel electrode 12 and the common electrode 20 (hereinafter referred to as OFF voltage), that is, when the liquid crystal molecules 23a are vertically aligned, circularly polarized light a ₂ passes without being almost the birefringence effect of the liquid crystal layer 23.

The polarization plane of the circularly polarized light a ₂ transmitted through the liquid crystal layer 23 is rotated by 90 degrees with respect to the linearly polarized light a ₁ transmitted through the front polarizing plate 25 and incident due to the phase difference of the second λ / 4 retardation plate 28. linearly polarized light becomes to the transmission axis 26a parallel to linearly polarized light a ₃ clogging rear polarizer 26, passes through the rear polarizer 26 emits the rear of the liquid crystal display panel 1 _(VA).

Then, the light (linearly polarized light) a ₃ emitted to the rear of the liquid crystal display panel 1 _(VA) is transmitted through the rear polarizing plate 26 and is incident on the dielectric layer 50. Of this light a ₃ , the dielectric layer The amount of light corresponding to the reflectance of 50 is reflected, and the amount of light corresponding to the transmittance of the dielectric layer 50 is transmitted through the dielectric layer 50.

The dielectric layer 50 is formed by alternately laminating optically isotropic first dielectric films 51 and second dielectric films 52 and has no polarization action. Therefore, both the light reflected by the dielectric layer 50 and the light transmitted through the dielectric layer 50 are the same linearly polarized light as the light a ₃ incident on the dielectric layer 50.

The light reflected by the dielectric layer 50, the transmission axis 26a parallel to the linearly polarized light a ₄ clogging rear polarizer 26 again enters from behind the liquid crystal display panel 1 _(VA). The linearly polarized light a ₄ passes through the rear polarizing plate 26 and is given a phase difference of λ / 4 wavelength by the second λ / 4 retardation plate 28 to become circularly polarized light a ₅ .

The circularly polarized light a ₅ is transmitted without receiving etc. N again殆birefringence effect of the liquid crystal layer 23, the phase difference of the first lambda / 4 phase plate 27, parallel to the transmission axis 25a of the front polarizer 25 enters the front polarizing plate 25 becomes a linearly polarized light a _6, and emits the transmitted this front polarizer 25 in front of the liquid crystal display panel 1 _(VA).

Of the light emitted to the rear of the liquid crystal display panel 1 _(VA) , the light transmitted through the dielectric layer 50 without being reflected by the dielectric layer 50 is reflected by the backlight 30 as shown in FIG. The light incident on the dielectric layer 50 from behind and the light transmitted through the dielectric layer 50 out of this light enters the liquid crystal display panel 1 _(VA) from the rear, passes through the liquid crystal display panel 1 _(VA) and forwards. To exit.

Further, of the light reflected from the backlight 30 and incident on the dielectric layer 50 from behind, the light reflected by the dielectric layer 50 is reflected by the backlight 30 again and enters the dielectric layer 50 from behind. Of this light, the light transmitted through the dielectric layer 50 (the amount of light corresponding to the transmittance of the dielectric layer 50) is incident on the liquid crystal display panel 1 _(VA) from the rear, and the liquid crystal display panel 1 _{(VA) ) And} exits forward.

Thus, when the OFF voltage is applied, the light that has entered the liquid crystal display panel 1 _(VA) from the front and absorbed the light of the polarization component parallel to the absorption axis of the front polarizing plate 25 is converted into the rear polarizing plate. 26 is emitted to the rear of the liquid crystal display panel 1 _(VA) with almost the absorption by 26, reflected by the dielectric layer 50 and the backlight 30, and emitted to the front of the liquid crystal display panel 1 _(VA) . Therefore, the display when the OFF voltage is applied in the reflective display is a bright display with a high emission light intensity.

Further, when a voltage (hereinafter referred to as an ON voltage) for tilting and aligning the liquid crystal molecules 23a is applied between the electrodes 12 and 20 of the liquid crystal display panel 1 _(VA) , the liquid crystal molecules 23a are turned into the electrode portions 12a and 12a of the pixel electrode 12, respectively. Each region corresponding to 12b and 12c falls radially and is oriented.

With such liquid crystal molecules 23a is tilting aligned, incident from the front on the liquid crystal display panel 1 _(VA), becomes circularly polarized light a ₂ passes through the front polarizing plate 25 a first lambda / 4 phase plate 27 in order The light incident on the liquid crystal layer 23 changes the polarization state due to the birefringence of the liquid crystal.

The light transmitted through the liquid crystal layer 23 while changing the polarization state is given a phase difference of λ / 4 wavelength by the second λ / 4 phase difference plate 28 and becomes light including polarization components in various directions. Of this light, light having a polarization component parallel to the absorption axis of the rear polarizing plate 26 is absorbed, and light having a polarization component parallel to the transmission axis 26 a is transmitted through the rear polarizing plate 26. To the rear of the liquid crystal display panel 1 _(VA) .

And the light radiate | emitted behind liquid crystal display panel 1 _(VA) is reflected by the dielectric material layer 50 and the backlight 30, and injects into liquid crystal display panel 1 _(VA) from back, and liquid crystal display panel 1 _{(VA) is made} into the back. Transmits and exits forward. Therefore, the display when the ON voltage is applied in the reflective display is a dark display with a low emission light intensity.

Next, transmissive display using illumination light from the backlight 30 will be described. As shown in FIG. 12B, the illumination light b ₀ emitted from the backlight 30 enters the dielectric layer 50, and this Of the light a ₃ , an amount of light corresponding to the reflectance of the dielectric layer 50 is reflected, and an amount of light corresponding to the transmittance of the dielectric layer 50 is transmitted through the dielectric layer 50. Since the dielectric layer 50 has no polarizing action, the light reflected by the dielectric layer 50 and the light transmitted through the dielectric layer 50 are both unpolarized light as the illumination light b ₀ from the backlight 30. is there.

The light transmitted through the dielectric layer 50 is incident on the liquid crystal display panel 1 _(VA) from behind, and is absorbed by the rear polarizing plate 26 with light having a polarization component parallel to the absorption axis, and is a straight line parallel to the transmission axis 26a. It becomes polarized light b ₁ and is further given a phase difference of ¼ wavelength by the second λ / 4 phase difference plate 28, and becomes circularly polarized light b ₂ and enters the liquid crystal layer 23.

Then, upon application of a OFF voltage between the pixel electrode 12 and the common electrode 20, the circularly polarized light b ₂ is transmitted without being almost the birefringence effect of the liquid crystal layer 23. The circularly polarized light b ₂ transmitted through the liquid crystal layer 23 has a plane of polarization of 90 degrees with respect to the linearly polarized light b ₁ transmitted through the rear polarizing plate 26 and incident due to the phase difference of the first λ / 4 retardation plate 27. Rotated linearly polarized light, that is, linearly polarized light b ₃ parallel to the transmission axis 25 a of the front polarizing plate 25, passes through the front polarizing plate 25, and exits in front of the liquid crystal display panel 1 _(VA) .

Of the illumination light b ₀ emitted from the backlight 30, the light reflected by the dielectric layer 50 is reflected by the backlight 30 as shown in FIG. 13 and again enters the dielectric layer 50 from behind, of this light, light transmitted through the dielectric layer 50 is incident from behind the liquid crystal display panel 1 _(VA), is emitted forward through the liquid crystal display panel 1 _(VA).

Further, of the light reflected from the backlight 30 and incident on the dielectric layer 50 from behind, the light reflected by the dielectric layer 50 is reflected by the backlight 30 again and enters the dielectric layer 50 from behind. Of this light, the light transmitted through the dielectric layer 50 (the amount of light corresponding to the transmittance of the dielectric layer 50) is incident on the liquid crystal display panel 1 _(VA) from the rear, and the liquid crystal display panel 1 _{(VA) ) And} exits forward.

As described above, when an OFF voltage is applied between the electrodes 12 and 20 of the liquid crystal display panel 1 _(VA) , the light is irradiated from the backlight 30 and transmitted through the dielectric layer 50 to the liquid crystal display panel 1 _(VA) . The light that has been absorbed from the light and the light of the polarization component that is parallel to the absorption axis of the rear polarizing plate 26 is emitted to the front of the liquid crystal display panel 1 _(VA) to receive almost all the absorption by the front polarizing plate 26. To do. Accordingly, the display when the OFF voltage is applied in the transmissive display is a bright display with a high intensity of emitted light.

Further, when applying a ON voltage between the electrodes 12, 20 of the liquid crystal display panel _{1 (VA)} collapse is oriented as in FIG. 5 of the liquid crystal molecules 23a are incident from behind the liquid crystal display panel _{1 (VA),} after The light that is transmitted through the side polarizing plate 26 and the second λ / 4 retardation plate 28 in order and becomes circularly polarized light b ₂ and enters the liquid crystal layer 23 changes the polarization state due to the birefringence of the liquid crystal.

Then, the light transmitted through the liquid crystal layer 23 while changing the polarization state is given light having a phase difference of λ / 4 wavelength by the first λ / 4 phase difference plate 27 and becomes light including polarization components in various directions. Of this light, light having a polarization component parallel to the absorption axis of the front polarization plate 25 is absorbed, and light having a polarization component parallel to the transmission axis 25a of the front polarization plate 25 is absorbed. 25 is transmitted to the front of the liquid crystal display panel 1 _(VA) . Therefore, the display when the ON voltage is applied in the transmissive display is a dark display with a low emission light intensity.

  As described above, the liquid crystal display device performs normally white mode display in which the display when the OFF voltage is applied is a bright display in both the reflective display and the transmissive display. Therefore, the brightness of the display is not reversed between the reflective display and the transmissive display.

In this liquid crystal display device, a dielectric layer 50 that reflects and transmits incident light at a predetermined reflectance and transmittance is disposed between the liquid crystal display panel 1 _(VA) and the backlight 30. Therefore, incident from the front, the light transmitted through the liquid crystal display panel 1 _(VA) reflected by the dielectric layer 50, a reflective display which emits the reflected light is again transmitted through the liquid crystal display panel 1 _(VA) on the front , and the illuminating light from the backlight 30 is transmitted through the dielectric layer 50 is incident from behind the liquid crystal display panel 1 _(VA), the transmissive display and for emitting light transmitted through the liquid crystal display panel 1 _(VA) on the front It can be performed.

Therefore, according to this liquid crystal display device, both the reflective display and the transmissive display can be performed without dividing each pixel of the liquid crystal display panel 1 _(VA) into the reflective display portion and the transmissive display portion.

  In addition, the dielectric layer 50 is formed by alternately laminating transparent first dielectric films 51 and second dielectric films 52 having different refractive indexes, and absorbs almost all incident light. Reflect and transmit without.

  That is, since the dielectric layer 50 used in the above embodiment has a characteristic that the total value of the average reflectance and the average transmittance for each wavelength light in the visible light band is 99% or more, the dielectric layer 50 The absorptance of light is 1% or less, and the incident light is reflected and transmitted with little absorption.

Therefore, the light incident from the front and transmitted through the liquid crystal display panel 1 _(VA) can be efficiently reflected by the dielectric layer 50 to perform a bright reflective display, and the illumination light from the backlight 30 can be efficiently dielectrically generated. The body layer 50 is transmitted and incident on the liquid crystal display panel 1 _(VA) , and bright transmissive display can be performed. Therefore, high display quality can be obtained in both reflective display and transmissive display.

  In the liquid crystal display device, the dielectric layer 50 preferably has characteristics such that the average reflectance is in the range of 55 to 60% and the average transmittance is in the range of 40 to 45%. In addition, by using the dielectric layer having the transmittance, it is possible to sufficiently brighten the reflective display that is performed preferentially, and also to ensure the brightness of the transmissive display.

  Furthermore, the dielectric layer 50 has an x coordinate value and a y coordinate value of the white point on the CIE chromaticity diagram of the reflected light when white light is incident, where x = 0.315 to 0.32 and y = 0. In the range of .315 to 0.32, the x coordinate value and the y coordinate value of the white point on the CIE chromaticity diagram of the transmitted light are x = 0.30 to 0.305 and y = 0.315 to 0.32. It has the spectral characteristics which are the range of.

  Therefore, the liquid crystal display device has very little band color of the reflected light and transmitted light from the dielectric layer 50 with respect to white light, and can produce a color image with high color reproducibility in both reflective display and transmissive display. Can be displayed.

  However, in the case of transmissive display, the light emitted from the light emitting element 36 (pseudo white light that is very close to white light) is guided in the light guide plate 31, and the wavelength of the reflectance of the emission surface 33 and the reflection surface 34 is reflected. It is tinted to some extent due to light dependency.

  Therefore, although the color reproducibility in transmissive display is reduced to some extent as compared with reflective display, this decrease in color reproducibility can be compensated for by adjusting the color of light emitted from the light emitting element 36. In that case, the color of the emitted light from the light emitting element 36 can be arbitrarily adjusted by changing the addition amount of the red fluorescent material 41 and the green fluorescent material 42 in the fluorescent layer 39.

  In addition, the light emitting element 36 is not limited to the one in the above embodiment, and may include, for example, red, green, and blue LEDs, and in that case, by controlling the light emission intensity of each color LED, The color of the emitted light can be adjusted arbitrarily.

In addition, the liquid crystal display device includes a dielectric layer 50 in which first dielectric films 51 and second dielectric films 52 are alternately stacked as a member that reflects and transmits light. Since the dielectric layer 50 is disposed between the liquid crystal display panel 1 _(VA) and the backlight 30, there is no restriction on the production of the liquid crystal display panel 1 _(VA) .

That is, when the dielectric layer 50 is disposed on the inner surface of the rear substrate 3 of the liquid crystal display panel 1 _(VA) , the gate electrode 7 is formed on the dielectric layer 50, and the film stress of the dielectric layer 50 is reduced. The liquid crystal display panel must be prepared in consideration of the film stress of the conductive film forming the gate electrode 7. In addition, since a thin film (transparent conductive film or the like) of TFT is formed on the dielectric layer 50, it is necessary to design the dielectric layer 50 in consideration of these refractive indexes. In that respect, since the dielectric layer 50 is disposed between the liquid crystal display panel 1 _(VA) and the backlight 30 in the liquid crystal display device, the manufacturing of the liquid crystal display device is not restricted.

Further, the liquid crystal display device has the backlight 30 having a function of reflecting light incident from the illumination light irradiation surface side toward the liquid crystal display panel 1 _(VA) . Therefore, in the reflective display, among the light emitted behind the liquid crystal display panel 1 _(VA) , the light transmitted through the dielectric layer 50 is reflected by the backlight 30, and this reflected light is reflected by the dielectric layers 50 and The liquid crystal display panel 1 _(VA) can be transmitted and emitted forward. Therefore, light incident from the front can be reflected more efficiently, and brighter reflective display can be performed.

In the case of transmissive display, light reflected from the dielectric layer 50 without being transmitted through the dielectric layer 50 out of the illumination light b ₀ emitted from the backlight 30 is reflected by the backlight 30. The reflected light can pass through the dielectric layer 50 and enter the liquid crystal display panel 1 _(VA) . Therefore, the illumination light from the backlight 30 can be reflected more efficiently and brighter transmissive display can be performed.

  Furthermore, in the above embodiment, the reflector 30 is disposed so that the backlight 30 faces the reflecting surface 34 of the light guide plate 31, and the first and second prism arrays 43 and 44 are disposed on the exit surface 33 of the light guide plate 31. With the arrangement, the light incident from the illumination light irradiation surface side can be efficiently reflected by the prism arrays 43 and 44, the reflection surface 34 and the reflection plate 35 of the light guide plate 31.

Moreover, in the said Example, the 1st ₍ lambda) / 4 phase difference plate 27 arrange | positioned between the front board | substrate 2 and the front side polarizing plate 25 in the liquid crystal display panel 1 _(VA) , the rear board | substrate 3, and the rear side polarization | polarized-light. Since the second λ / 4 phase difference plate 28 disposed between the plate 26 and the plate 26 is provided, the reflective display and the transmissive display can be brightened.

  That is, in the case of a vertical alignment type liquid crystal display panel that does not include a λ / 4 retardation plate, the linearly polarized light that has passed through the polarizing plate on the incident side (front side in the case of reflection display and rear side in the case of transmission display) Therefore, the change in the polarization state of the incident light when the liquid crystal molecules are tilted and aligned is smaller than the change in the polarization state when the circularly polarized light is incident. Therefore, most of the light transmitted through the liquid crystal layer is absorbed by the polarizing plate on the emission side, and the dark display becomes close to black.

On the other hand, in the liquid crystal display panel 1 _(VA) of the above embodiment, the linearly polarized light transmitted through the incident-side polarizing plate is changed to circularly polarized light by the incident-side λ / 4 retardation plate and is incident on the liquid crystal layer. The change in the polarization state of incident light when the liquid crystal molecules are tilted and aligned is large. The light transmitted through the liquid crystal layer is incident on the exit-side polarizing plate as light containing polarization components in various directions due to the phase difference of the exit-side λ / 4 retardation plate. Among them, the light of the polarization component parallel to the transmission axis of the output side polarizing plate is transmitted through and emitted from the output side polarizing plate without being absorbed.

Therefore, the liquid crystal display panel 1 _(VA) of the above embodiment emits a certain amount of light from the dark display portion. Therefore, the reflective display and the transmissive display can be brightened as compared with the vertical alignment type liquid crystal display panel that does not include the λ / 4 retardation plate.

[Second Example]
The second embodiment shown in FIG. 14 is a liquid crystal display device according to the first embodiment, in which a transmission axis 60a and a reflection axis are arranged between the liquid crystal display panel 1 _(VA) and the dielectric layer 50 in directions orthogonal to each other. The reflective polarizing plate 60 which has 60b, permeate | transmits the light of the polarization component parallel to the transmission axis 60a, and reflects the light of the polarization component parallel to the reflection axis 60b is further arrange | positioned.

The reflection polarizing plate 60 is disposed such that the reflection axis 60b is obliquely intersected with the transmission axis 26a of the rear polarizing plate 26 of the liquid crystal display panel 1 _{(VA) at} a predetermined angle (for example, 45 °), thereby diffusing light. The adhesive layer 61 in which particles are dispersed is attached to the outer surface of the rear polarizing plate 26. In addition, since the other structure of this 2nd Example is the same as the liquid crystal display device of a 1st Example, the overlapping description attaches | subjects the same code | symbol to a figure and abbreviate | omits.

In the liquid crystal display device according to the second embodiment, the reflective polarizing plate 60 is disposed between the liquid crystal display panel 1 _(VA) and the dielectric layer 50 so that the liquid crystal display panel 1 _(VA) is incident from the front side. The transmitted light is reflected by the reflective polarizing plate 60, the dielectric layer 50, and the backlight 30.

That is, FIG. 15 is a schematic diagram of reflective display and transmissive display by the liquid crystal display device of the second embodiment, FIG. 15A shows light emission in the reflective display, and FIG. 15B shows transmissive display. The light emission in FIG. Note that the change in the polarization state of the light transmitted through the liquid crystal display panel 1 _(VA) during the reflective display and the transmissive display according to the second embodiment is the same as that in the first embodiment. Is omitted.

As shown in FIG. 15A, in the case of reflective display, as shown in FIG. 15A, light that has entered from the front and transmitted through the liquid crystal display panel 1 _(VA) (the transmission axis 26a of the rear polarizing plate 26 _). (A linearly polarized light) a ₃ is incident on the reflective polarizing plate 60, and among the light a ₃ , light having a polarization component parallel to the reflective axis 60 b of the reflective polarizing plate 60 is reflected, and the transmission axis of the reflective polarizing plate 60 is reflected. Light having a polarization component parallel to 60 a is transmitted through the reflective polarizing plate 60.

Reflection amount and transmission amount by the reflective polarizer 60 of the linearly polarized light a ₃ corresponds to the intersection angle between the reflection axis 60b of the transmission axis 26a of the rear polarizer 26 reflective polarizer 60, crossing angle is 45 ° some time, about half of linearly polarized light a ₃ is reflected and the other about half is transmitted.

The light reflected by the reflective polarizer 60 is incident from behind the liquid crystal display panel 1 _(VA), is emitted forward through the liquid crystal display panel 1 _(VA).

In addition, the light transmitted through the reflective polarizing plate 60 is reflected by the dielectric layer 50 or transmitted through the dielectric layer 50 and reflected by the backlight 30 as in FIG. 50 is transmitted again and reenters the reflective polarizing plate 60. Then, these light, light transmitted through the reflective polarizer 60 is incident from behind the liquid crystal display panel 1 _(VA), is emitted forward through the liquid crystal display panel 1 _(VA).

As described above, in the liquid crystal display device of the second embodiment, the light incident from the front and transmitted through the liquid crystal display panel 1 _(VA) is reflected by the reflective polarizing plate 60, the dielectric layer 50, and the backlight 30. Therefore, the light incident from the front and transmitted through the liquid crystal display panel 1 _(VA) can be efficiently reflected, and bright and high-quality reflective display can be performed.

On the other hand, at the time of transmissive display, as shown in FIG. 15B, the illumination light b ₀ irradiated from the backlight 30 and transmitted through the dielectric layer 50 enters the reflective polarizing plate 60, and the illumination light b ₀ Among them, light having a polarization component parallel to the transmission axis 60 a of the reflective polarizing plate 60 passes through the reflective polarizing plate 60 and enters the liquid crystal display panel 1 _(VA) .

Of the illumination light b ₀ incident on the reflective polarizing plate 60, light having a polarization component parallel to the reflection axis 60 b of the reflective polarizing plate 60 is reflected by the reflective polarizing plate 60. The reflected light is reflected by the dielectric layer 50, or is transmitted through the dielectric layer 50 and reflected by the backlight 30, and is again transmitted through the dielectric layer 50 and reenters the reflective polarizing plate 60. Then, these light, light transmitted through the reflective polarizer 60 is incident from behind the liquid crystal display panel 1 _(VA), is emitted forward through the liquid crystal display panel 1 _(VA).

Therefore, the liquid crystal display device can efficiently illuminate the illumination light from the backlight 30 to the liquid crystal display panel 1 _(VA) and perform a bright display with high display quality.

In the second embodiment, the crossing angle between the transmission axis 26a of the rear polarizing plate 26 of the liquid crystal display panel 1 _(VA) and the reflection axis 60b of the reflective polarizing plate 60 may be an angle other than 45 °. The smaller the crossing angle is, the smaller the deviation angle of the reflection axis 60b of the reflective polarizing plate 60 from the transmission axis 26a of the rear polarizing plate 26 is, and the linearly polarized light a emitted to the rear of the liquid crystal display panel 1 _{(VA). The} amount of reflection by the reflective polarizing plate 60 of ₃ increases. Therefore, it is possible to more efficiently reflect the light incident from the front and transmitted through the liquid crystal display panel 1 _(VA), and to perform bright and high-quality reflection display.

  In the second embodiment, the reflective polarizing plate 60 may be disposed between the dielectric layer 50 and the backlight 30. In this case as well, a bright high display quality reflective display and transmissive display are performed. Can do.

[Third embodiment]
In the third embodiment shown in FIG. 16, in the liquid crystal display device of the first embodiment, the base film 53 of the dielectric layer 50 is omitted, and the dielectric layer 50 is used as the rear polarization of the liquid crystal display panel 1 _(VA). It is formed on the outer surface of the plate 26. In addition, since the other structure of this 2nd Example is the same as that of a 1st Example, the overlapping description attaches | subjects the same code | symbol to a figure and abbreviate | omits.

  According to the third embodiment, compared to the liquid crystal display device of the first embodiment, there is no loss of light due to absorption by the base film 53 of the dielectric layer 50, so that the reflective display and the transmissive display are brightened. Can do.

[Fourth embodiment]
In the fourth embodiment shown in FIG. 17, in the liquid crystal display device of the second embodiment, the base film 53 of the dielectric layer 50 is omitted, and the dielectric layer 50 faces the backlight 30 of the reflective polarizing plate 60. It is formed on the surface. In addition, since the other structure of this 2nd Example is the same as 2nd Example, the overlapping description attaches | subjects the same code | symbol to a figure and abbreviate | omits.

  According to the fourth embodiment, compared to the liquid crystal display device of the second embodiment, there is no loss of light due to absorption by the base film 53 of the dielectric layer 50, so that the reflective display and the transmissive display are brightened. Can do.

[Fifth Example]
In the fifth embodiment shown in FIG. 18, in the liquid crystal display device of the second embodiment, the base film 53 of the dielectric layer 50 is omitted, and the dielectric layer 50 is used as the rear polarization of the liquid crystal display panel 1 _(VA). In addition to being formed on the outer surface of the plate 26, the reflective polarizing plate 60 is integrally laminated on the second prism array 44 of the backlight 30.

  In the fifth embodiment, the reflective polarizing plate 60 is integrally attached on the flat surface of the second prism array 44 of the backlight 30. The second prism array 44 is disposed with the surface opposite to the surface to which the reflective polarizing plate 60 is attached, that is, the surface on which the prism portion 44 a is formed facing the first prism array 43. In addition, since the other structure of this 5th Example is the same as 2nd Example, the overlapping description attaches | subjects the same code | symbol to a figure and abbreviate | omits.

  According to the fifth embodiment, since there is no light loss due to absorption by the base film 53 of the dielectric layer 50 as compared with the liquid crystal display device of the second embodiment, the reflective display and the transmissive display are made brighter. In addition, since the reflective polarizing plate 60 is integrally laminated on the second prism array 44 of the backlight 30, the liquid crystal display device can be assembled when the reflective polarizing plate 60 is disposed as an independent component. The reflective polarizing plate 60 does not need to be aligned with the transmission axis 60a and the reflection axis 61b in a predetermined direction.

[Sixth embodiment]
In the sixth embodiment shown in FIG. 19, in the liquid crystal display device of the second embodiment, the backlight 30 is provided with a diffusion sheet 46 disposed on the second prism array 44, and the dielectric layer 50 is provided. Is formed on the diffusion sheet 46. In addition, since the other structure of this 6th Example is the same as that of 2nd Example, the overlapping description attaches | subjects the same code | symbol to a figure and abbreviate | omits.

  In this sixth embodiment, the diffusion sheet 46 is made of a transparent resin sheet in which light diffusion particles are dispersed, and the surface of the diffusion sheet 46 has a minute size corresponding to the distribution of light diffusion particles near the sheet surface. It has an uneven surface. Therefore, the dielectric layer 50 can be formed in close contact with the diffusion sheet 46.

  In addition, when the dielectric layer 50 is formed on the diffusion sheet 46, the unevenness formed on the surface of the diffusion sheet 46 makes the surface of the diffusion sheet 46 not a mirror surface but a whitish semi-transmissive layer and improves the scattering performance.

[Seventh embodiment]
The seventh embodiment shown in FIG. 20 includes a TN liquid crystal display panel 1 _(TN) as a liquid crystal display panel. In the seventh embodiment, components corresponding to those of the liquid crystal display device of the first embodiment are given the same reference numerals, and description of the same components is omitted.

The TN liquid crystal display panel 1 _(TN) has a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy, and twists liquid crystal molecules between the front substrate 2 and the rear substrate 3 with a twist angle of 90 degrees. It is oriented and includes a front polarizing plate 25 disposed on the outer surface of the front substrate 2 and a rear polarizing plate 26 disposed on the outer surface of the rear substrate 3.

This TN liquid crystal display panel 1 _(TN) is an active matrix liquid crystal display panel using TFTs as switching elements, and is provided on the inner surface of the rear substrate 3 (the surface facing the front substrate 2) on the scanning signal line and the data signal line. A plurality of connected TFTs and a plurality of pixel electrodes respectively connected to each TFT are provided, and a common electrode facing each pixel electrode is provided on the inner surface of the front substrate 2 (a surface facing the rear substrate 3). ing.

  Further, a horizontal alignment film that is rubbed in a direction orthogonal to each other is provided on the inner surface of the front substrate 2 and the inner surface of the rear substrate 3. In FIG. 20, 2r indicates the rubbing direction of the horizontal alignment film provided on the inner surface of the front substrate 2, 3r indicates the rubbing direction of the horizontal alignment film provided on the inner surface of the rear substrate 3, and the liquid crystal molecules of the liquid crystal layer are From the rear substrate 3 toward the front substrate 2, twist orientation is performed at a twist angle of 90 degrees in the direction indicated by the broken line arrow in FIG. 20. Further, both the front polarizing plate 25 and the rear polarizing plate 26 are absorption polarizing plates, and are arranged so that the transmission axes 25a and 26a are orthogonal to each other.

In the liquid crystal display device according to the seventh embodiment, the dielectric layer 50 is disposed between the TN type liquid crystal display panel 1 _(TN) and the backlight 30, and further the TN type liquid crystal display panel 1 _(TN) and the dielectric. A diffusion layer 62 is disposed between the body layer 50 and the body layer 50. The diffusion layer 62 is made of a transparent adhesive layer in which light scattering particles are dispersed. The dielectric layer 50 is formed on the outer surface of the rear polarizing plate 26 of the _TN liquid crystal display panel 1 _(TN) by the diffusion layer 62. It is pasted.

Also in this liquid crystal display device, since the dielectric layer 50 is disposed between the TN type liquid crystal display panel 1 _(TN) and the backlight 30, each pixel of the liquid crystal display panel 1 _(TN) is used as a reflective display unit. Reflective display and transmissive display can be performed without being divided into transmissive display portions, and high display quality can be obtained.

  In the seventh embodiment, the dielectric layer 50 is formed on the base film 53. However, instead of the diffusion layer 62, a diffusion sheet is disposed and the surface of the diffusion sheet facing the backlight 30 is provided. The base film 53 may be omitted by forming the dielectric layer 50 thereon.

Further, in the TN type liquid crystal display panel 1 _(TN) , a first λ / 4 retardation plate is disposed between the front substrate 2 and the front polarizing plate 25, and between the rear substrate 3 and the rear polarizing plate 26. Further, a second λ / 4 retardation plate may be disposed.

Further, a reflective polarizing plate 60 is arranged between the TN type liquid crystal display panel 1 _(TN) and the dielectric layer 50 or between the dielectric layer 50 and the backlight 30 as in the second embodiment. Also good.

[Other embodiments]
In each of the above embodiments, the backlight 30 is provided with the first and second prism arrays 43 and 44, but the prism array may be either the first or the second.

  In addition, the liquid crystal display panel is not limited to a vertical alignment type or a TN type, but is an STN type in which liquid crystal molecules are twisted with a twist angle of 180 ° to 270 °, and the liquid crystal molecules are aligned in the same direction in the molecular long axis. Or a non-twisted horizontal alignment type that is aligned substantially in parallel with each other, a bend alignment type that bends liquid crystal molecules, or a ferroelectric or antiferroelectric liquid crystal display panel.

  Further, the liquid crystal display panel is provided with a pixel electrode connected to the TFT on the inner surface of the rear substrate 3, and a shared electrode arranged to be insulated from the pixel electrode on the liquid crystal layer side or the substrate side with respect to the pixel electrode, By forming a plurality of slits in the electrode on the liquid crystal layer side of the pixel electrode and the shared electrode, a horizontal electric field (an electric field in a direction along the substrate surface) is generated between the pixel electrode and the shared electrode, and the liquid crystal molecules A lateral electric field control type that changes the alignment state may be used.

1 _(VA) ... vertical alignment type liquid crystal display panel, 1 _(TN) ... TN type liquid crystal display panel, 2 ... front substrate, 3 ... rear substrate, 4 ... scanning signal line, 5 ... data signal line, 6 ... TFT, 12 ... pixel electrode, 20 ... common electrode, 23 ... liquid crystal layer, 23a ... liquid crystal molecule, 25, 26 ... polarizing plate, 25a, 26a ... transmission axis, 37, 28 ... λ / 4 phase difference plate, 37a, 28a ... slow phase Axis 30 ... Backlight 31 ... Light guide plate 32 ... Incident surface 33 ... Emission surface 34 ... Reflective surface 35 ... Reflector plate 36 ... Light emitting element 43, 44 ... Prism array 34a, 44a ... Prism part , 46 ... diffusion sheet, 50 ... dielectric layer, 51, 52 ... dielectric film, 53 ... base film, 60 ... reflective polarizing plate, 60a ... transmission axis, 60b ... reflection axis

Claims (17)

A liquid crystal layer sealed between the front substrate and the rear substrate disposed opposite to each other, a front polarizing plate disposed on the outer surface of the front substrate, and a rear polarizing plate disposed on the outer surface of the rear substrate, A liquid crystal display panel for performing display by controlling the light transmittance of each pixel by applying a voltage to the liquid crystal layer;
A backlight that is arranged behind the liquid crystal display panel and that irradiates illumination light toward the liquid crystal display panel from an irradiation surface facing the liquid crystal display panel;
A dielectric layer disposed between the liquid crystal display panel and the backlight;
With
The dielectric layer is formed by alternately laminating transparent first dielectric films and second dielectric films having different refractive indexes, and passes through the liquid crystal display panel toward the dielectric layer. A liquid crystal display device characterized in that part of external light is reflected and the other part is transmitted. The liquid crystal display device according to claim 1, wherein the first dielectric film is Nb ₂ O ₅ or TiO ₂ , and the second dielectric film is SiO ₂ . 3. The liquid crystal display device according to claim 2, wherein the average reflectance with respect to each wavelength light in the visible light band of the dielectric layer is 55 to 60%. 4.   3. The liquid crystal display device according to claim 2, wherein the dielectric layer has an average transmittance of 40 to 45% with respect to each wavelength light in a visible light band.   5. The liquid crystal according to claim 3, wherein the dielectric layer has a characteristic that a total value of an average reflectance and an average transmittance for each wavelength light in a visible light band is 99% or more. Display device.   The liquid crystal according to claim 1, wherein the dielectric layer is formed on a transparent base film and is disposed between the liquid crystal display panel and the backlight. Display device.   The dielectric layer has an x coordinate value and a y coordinate value of the white point on the CIE chromaticity diagram of the reflected light when white light is incident, x = 0.315 to 0.32, y = 0.315. In the range of -0.32, the x coordinate value and y coordinate value of the white point on the CIE chromaticity diagram of the transmitted light are in the range of x = 0.30-0.305 and y = 0.315-0.32. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a spectral characteristic as follows.   The said backlight has a function which reflects the light which injected from the irradiation surface side of the said illumination light toward the said liquid crystal display panel, The Claim 1 characterized by the above-mentioned. Liquid crystal display device. The backlight is
An incident surface that is made of a plate-shaped transparent member is formed to allow light to be incident on at least one end surface, and an exit surface that emits light incident from the incident surface is formed on one of the two plate surfaces. A light guide plate formed with a reflection surface that internally reflects light incident from the incident surface toward the emission surface;
A reflector disposed to face the reflecting surface of the light guide plate;
A light emitting element disposed to face the incident surface of the light guide plate;
A plurality of prism portions are formed on one surface of the transparent sheet-like member, and a prism array disposed on the emission surface of the light guide plate;
With
9. The liquid crystal display device according to claim 8, wherein a surface on which the prism array is disposed is disposed so as to face the dielectric layer.   Between the liquid crystal display panel and the dielectric layer, or between the dielectric layer and the backlight, have a transmission axis and a reflection axis in directions orthogonal to each other, and a polarization component parallel to the transmission axis. 10. The liquid crystal display device according to claim 1, further comprising a reflective polarizing plate that transmits light and reflects light having a polarization component parallel to the reflection axis.   The liquid crystal display device according to claim 1, wherein the dielectric layer is formed on an outer surface of the rear polarizing plate of the liquid crystal display panel.   The liquid crystal display device according to claim 10, wherein the dielectric layer is formed on a surface of the reflective polarizing plate facing the backlight.   10. The liquid crystal display device according to claim 9, wherein the backlight includes a diffusion sheet disposed on the prism array, and the dielectric layer is formed on the diffusion sheet. .   The liquid crystal display panel is an active matrix liquid crystal display panel using thin film transistors as switching elements, and a plurality of thin film transistors connected to scanning signal lines and data signal lines on a surface of the rear substrate facing the front substrate; 2. A plurality of pixel electrodes respectively connected to each thin film transistor are provided, and a common electrode facing each pixel electrode is provided on a surface of the front substrate facing the rear substrate. 14. The liquid crystal display device according to any one of items 13 to 13.   The liquid crystal display panel has a liquid crystal layer made of nematic liquid crystal having negative dielectric anisotropy, and a vertical alignment type liquid crystal display panel in which liquid crystal molecules are aligned perpendicular to the plate surfaces of the front substrate and the rear substrate. The liquid crystal display device according to claim 14, wherein the liquid crystal display device is a liquid crystal display device.   The liquid crystal display panel is a TN liquid crystal display panel having a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy and having liquid crystal molecules twist-aligned between the front substrate and the rear substrate. The liquid crystal display device according to claim 14.   The liquid crystal display panel includes a first λ / 4 retardation plate disposed between the front substrate and the front polarizing plate, and a second λ / 4 retardation plate disposed between the rear substrate and the rear polarizing plate. The liquid crystal display device according to claim 1, further comprising: a λ / 4 retardation plate.

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