JP4985798B2 - Liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal display element.

  As a liquid crystal display element, a liquid crystal layer in which liquid crystal molecules are twist-aligned is provided between a pair of substrates provided with electrodes that form a plurality of pixels arranged in a matrix by regions facing each other on opposite surfaces. A twist alignment type liquid crystal element that changes the polarization state of transmitted light by controlling the rising angle of the liquid crystal molecules of the liquid crystal layer with respect to the substrate surface by applying a voltage between the electrodes, and sandwiching the twist alignment type liquid crystal element Although a TN (twisted nematic) type composed of a pair of arranged polarizing plates is widely used, this TN type liquid crystal display element has a narrow display viewing angle.

  Therefore, it is considered that a viewing angle of display is widened by disposing a discotic liquid crystal film between the twist alignment type liquid crystal element and the pair of polarizing plates, respectively (see Patent Document 1).

Japanese Patent Laid-Open No. 10-039285

  However, even with a TN liquid crystal display element in which a discotic liquid crystal film is disposed between a twist alignment type liquid crystal element and a pair of polarizing plates, the viewing angle is not sufficient, and depending on the viewing direction of the display, On the other hand, when observed from a direction inclined at a certain angle or more, a contrast inversion phenomenon occurs in which the luminance of black display and gray display is reversed.

  It is an object of the present invention to provide a liquid crystal display element that is capable of obtaining a high-contrast display with no contrast inversion over a wide range of viewing directions and viewing angles.

The liquid crystal display device of this invention, the molecular long axes homogeneous alignment liquid crystal layer of the non-twist aligned homogeneously the liquid crystal molecules are aligned in one direction on each opposite to that surface of the pair of substrates sandwiching by a region facing each other Homogeneous having electrodes that form a plurality of pixels arranged in a matrix, and changing the polarization state of transmitted light by controlling the rising angle of the liquid crystal molecules with respect to the substrate surface of the liquid crystal layer by applying a voltage between the electrodes An alignment type liquid crystal element, first and second discotic liquid crystal films that sandwich the homogeneous alignment type liquid crystal element , and first and second biaxial axes that sandwich the first and second discotic liquid crystal films First and second uniaxial phase plates sandwiching the first and second biaxial phase plates, and the first and second uniaxial phase plates Sandwiching and first and second polarizing plates, and the surface light source in one of the outer surface side one of said first and second polarizing plates, comprising the.

In the liquid crystal display device of the present invention, the slow axis along the direction in which the refractive index is the largest on the phase plate surface of the first and second biaxial phase plates, and the first and second discotic liquid crystal films optical axis and the plane on the optical axis obtained by projecting the film surface, but for the homogeneous orientation type is parallel to the liquid crystal molecular alignment direction of the liquid crystal element, before Symbol slow axis of the first biaxial phase plate adjacent each The shift angle of the slow axis of the first uniaxial phase plate is φ1, the shift angle of the slow axis of the second uniaxial phase plate with respect to the slow axis of the second biaxial phase plate is φ2, The angle of deviation of the absorption axis of the first polarizing plate with respect to the slow axis of the first biaxial phase plate is θ1, and the second polarizing plate with respect to the slow axis of the second biaxial phase plate is the deviation angle of the absorption axis and .theta.2, and, on the opposite side to the surface light source the first and second polarization One of the outer surface of the angle of counterclockwise positive as viewed from the side angle, when the angle of the clockwise and negative angle, the slow axis and the first of said first and second uniaxial phase plate And the direction of the absorption axis of the second polarizing plate is
φ1 = 60 ° -80 °
φ2 = -60 ° ~ -80 °
θ1 = 135 ° + 2φ1
θ2 = 135 ° + 2φ2
It is preferable to set in the direction.

Furthermore, the first and has a phase difference in the range of each second uniaxial phase plate 250-300 nm, the first and second biaxial phase plate respectively is 1 20 nm to 150 nm of A direction having an in-plane retardation within a range and having the largest refractive index on the phase plate surface is the x axis, a direction perpendicular to the x axis is the y axis, and a direction perpendicular to the phase plate surface when was the z axis, the x-axis direction of the refractive index n _x, the y-axis direction of the refractive index n _y, the refractive index of the z-axis direction is n _{z,
Nz = (n x -n z)} / (n x -n y)
It is desirable to have an Nz coefficient in the range of -0.5 to +0.3.

In the liquid crystal display device of the present invention, in any one surface of the pair of substrates facing the homogeneous alignment liquid crystal element, red corresponding to a plurality of pixels, green, color filters of three colors of blue Among the plurality of pixels, a liquid crystal refractive index anisotropy Δn and a liquid crystal layer thickness d of a pixel corresponding to a red filter, a pixel corresponding to a green filter, and a pixel corresponding to a blue filter The value of the product Δn · d is d _R for the liquid crystal layer thickness of the pixel corresponding to the red filter, d _G for the liquid crystal layer thickness of the pixel corresponding to the green filter, and the liquid crystal layer thickness of the pixel corresponding to the blue filter. was a _{d B,} 650 nm of the liquid crystal refractive index anisotropy [Delta] n, 550 nm, respectively a value for each wavelength of 450nm Δn (650nm), Δn ( 550nm), when the [Delta] n (450 nm),
255 nm <Δn (550 nm) · d _G <355 nm
−25 nm <Δn (650 nm) · d _R −Δn (550 nm) · d _G <+30 nm
−35 nm <Δn (450 nm) · d _B −Δn (550 nm) · d _G <+10 nm
It is desirable to set the range.
Further, the first and second discotic liquid crystal films are formed by aligning disc-shaped discotic liquid crystal molecules in one direction and gradually tilting from one surface to the other surface. It is a polymer that is arranged so as to increase in size, and is arranged in the tilted state from one film surface side where the tilt angle of liquid crystal molecules is small toward the other film surface side where the tilt angle of liquid crystal molecules is large. A tick liquid crystal molecule, that is, a tilted optical axis inclined obliquely in a direction averaged with respect to the direction of the axis perpendicular to the disc-like molecular plane, and the refractive index in the direction along the tilted optical axis is It is desirable to have the smallest negative optical anisotropy.
Further, the polarizing plate on the surface light source side, the uniaxial phase plate and the biaxial phase plate function as a wide-band circular polarizing plate, and the polarizing plate on the side opposite to the surface light source And the uniaxial phase plate and the biaxial phase plate function as a wide-band circularly polarizing plate, and the homogeneously aligned liquid crystal element is a λ / 2 plate that gives a phase difference of ½ wavelength It is desirable to function as an optical element that switches between this state and a state that does not give a phase difference by voltage.

The liquid crystal display device of the invention, over the observation azimuth and viewing angle have wide, can contrast reversal is obtained without addition of high-contrast display.

1 is an exploded perspective view of a liquid crystal display element showing one embodiment of the present invention. FIG. 3 is a cross-sectional view of a part of the liquid crystal display element. The figure which shows the change of the white display brightness | luminance by the viewing angle in the left-right direction of the said liquid crystal display element, the change of black display brightness, and the change of contrast. The figure which shows the change of the white display brightness | luminance by the visual angle in the up-down direction of the said liquid crystal display element, the change of black display brightness, and the change of contrast. The figure which shows the contrast inversion characteristic by the viewing angle of the said liquid crystal display element. The figure which shows the relationship between the liquid-crystal layer thickness of the said liquid crystal display element, and the transmittance | permeability of light. The figure which shows the relationship between the liquid crystal layer thickness of the said liquid crystal display element, and the chromaticity of transmitted light. The figure which shows the voltage-transmittance characteristic of the center wavelength light of the red, green, blue wavelength range of the said liquid crystal display element. The enlarged view of the part where the transmittance | permeability of FIG. 8 became the lowest. The figure which shows the relationship between the optimal black display voltage with respect to the center wavelength light of the wavelength range of red of the said liquid crystal display element, and blue, and a liquid crystal layer thickness.

  1 to 10 show an embodiment of the present invention. FIG. 1 is an exploded perspective view of a liquid crystal display element, and FIG. 2 is a sectional view of a part of the liquid crystal display element.

  As shown in FIGS. 1 and 2, the liquid crystal display element of this embodiment includes a homogeneous alignment type liquid crystal element 1 and first and second polarizing plates 12 and 13 disposed with the liquid crystal element 1 interposed therebetween. The first and second discotic liquid crystal films 14 and 15 disposed between the liquid crystal element 1 and the first and second polarizing plates 12 and 13, respectively, and the first polarizing plate The first uniaxial phase plate 16 and the first biaxial phase plate 18 which are disposed so as to overlap each other between the first discotic liquid crystal film 12 and the first discotic liquid crystal film 14, the second polarizing plate 13 and the second polarizing plate 13. A second uniaxial phase plate 17 and a second biaxial phase plate 19 are provided so as to overlap each other with the discotic liquid crystal film 15.

  As shown in FIG. 2, the homogeneous alignment type liquid crystal element 1 includes a pair of transparent layers facing each other with a non-twisted homogeneous alignment liquid crystal layer 11 in which the liquid crystal molecules 11a are aligned homogeneously with the molecular long axis aligned in one direction. Each of the opposing inner surfaces of the substrates 2 and 3 is provided with transparent electrodes 4 and 5 for forming a plurality of pixels arranged in a matrix by regions facing each other, and one of the pair of substrates 2 and 3 For example, on the inner surface of the front substrate (hereinafter referred to as the front substrate) 2 that is the observation side (upper side in the drawing) of the display, color filters 7R of three colors of red, green, and blue corresponding to the plurality of pixels, respectively. 7G and 7B are provided.

  This liquid crystal element 1 is provided with a single film-like counter electrode 4 on one of a pair of substrates 2 and 3, for example, the inner surface of the front substrate 2, and a rear substrate (hereinafter referred to as a rear substrate) which is the other substrate. 3 is an active matrix liquid crystal element in which a plurality of pixel electrodes 5 are arranged in a matrix in the row direction and the column direction, and the plurality of pixel electrodes 5 are provided on the inner surface of the rear substrate 3. The TFTs (thin film transistors) 6 are respectively connected.

  In FIG. 2, the TFT 6 is shown in a simplified form. This TFT 6 is a gate electrode formed on the substrate surface of the rear substrate 3 and a transparent electrode that covers the gate electrode and is formed on substantially the entire rear substrate 3. A gate insulating film, an i-type semiconductor film formed on the gate insulating film so as to face the gate electrode, and an n-type semiconductor film formed on both sides of the i-type semiconductor film It consists of a source electrode and a drain electrode.

  Further, although omitted in FIG. 2, on the inner surface of the rear substrate 3, there are a plurality of gate wirings for supplying gate signals to the TFTs 6 in each row and a plurality of data wirings for supplying data signals to the TFTs 6 in each column. The gate wiring is formed integrally with the gate electrode of the TFT 6 on the substrate surface of the rear substrate 3 and covered with the gate insulating film, and the data wiring is formed on the gate insulating film. , Connected to the drain electrode of the TFT 6.

  The plurality of pixel electrodes 5 are formed on the gate insulating film and connected to the source electrode of the TFT 6.

On the other hand, the three color filters 7R, 7G, and 7B of red, green, and blue provided on the inner surface of the front substrate 2 are formed on the substrate surface of the front substrate 2, and the three color filters are formed thereon. color filters 7R, 7G, among 7B, pixels red filter 7R is provided (hereinafter, referred to as red pixels) and a liquid crystal layer thickness d _R of the pixel of the green filter 7G is provided (hereinafter, referred to as a green pixel) LCD and the layer thickness _{d G,} pixels blue filter 7B is provided (hereinafter, referred to as a blue pixel) and a liquid crystal layer thickness _{d B of, d R>} d _G> d transparent liquid crystal layer thickness for setting the relationship of _B An adjustment film 8 is provided, and the counter electrode 4 is formed on the liquid crystal layer thickness adjustment film 8.

  Further, horizontal alignment films 9 and 10 are provided on the inner surfaces of the front substrate 2 and the rear substrate 3 so as to cover the electrodes 4 and 5, respectively, and the inner surfaces of these substrates 2 and 3, that is, the horizontal alignment film 9. , 10 are rubbed in parallel and in opposite directions.

  In FIG. 1, the arrow 2a indicates the rubbing direction of the inner surface of the front substrate 2, and the arrow 3a indicates the rubbing direction of the inner surface of the rear substrate 3. In this embodiment, the first and second polarizing plates 12, 13 Any one of the rubbing directions 2a on the inner surface of the front substrate 2 when the counterclockwise angle is a positive angle and the clockwise angle is a negative angle when viewed from the outer surface side of the front polarizing plate 12 that is the observation side, for example. The direction of 135 ° with respect to the horizontal axis x of the screen of the liquid crystal element, and the rubbing direction 3a of the inner surface of the rear substrate 3 are parallel to and opposite to the rubbing direction 2a of the inner surface of the front substrate 2 (screen The liquid crystal molecules 11a are homogeneously aligned in the direction along the rubbing directions 2a and 3a.

  The pair of substrates 2 and 3 are joined together via a frame-shaped sealing material (not shown) surrounding a display area in which the plurality of pixels are arranged in a matrix. A region surrounded by the sealing material is filled with nematic liquid crystal having positive dielectric anisotropy to form a liquid crystal layer 11.

  The liquid crystal molecules 11a of the liquid crystal layer 11 are homogeneously aligned with the molecular long axes aligned in the direction along the rubbing directions 2a and 3a of the pair of substrates 2 and 3, and the electrodes 4 and 5 of the plurality of pixels. By applying a voltage between them, the orientation state is changed so as to rise with respect to the surfaces of the substrates 2 and 3.

  That is, the homogeneous alignment type liquid crystal device 1 controls the rising angle of the liquid crystal molecules 11a of the liquid crystal layer 11 with respect to the substrates 2 and 3 by applying a voltage between the electrodes 4 and 5 of the plurality of pixels. Change the polarization state of.

The product Δn · d of the refractive index anisotropy Δn and the liquid crystal layer thickness d of the liquid crystals of the red, green, and blue pixels of the homogeneous alignment type liquid crystal element 1 is the liquid crystal layer thickness of the red pixel, respectively. D _R , the liquid crystal layer thickness of the green pixel is d _G , the liquid crystal layer thickness of the blue pixel is d _B , and the value of the refractive index anisotropy Δn of the liquid crystal with respect to light of each wavelength of 650 nm, 550 nm, and 450 nm is Δn (650 nm), Δn (550 nm), Δn (450 nm),
255 nm <Δn (550 nm) · d _G <355 nm
−25 nm <Δn (650 nm) · d _R −Δn (550 nm) · d _G <+30 nm
−35 nm <Δn (450 nm) · d _B −Δn (550 nm) · d _G <+10 nm
Is set in the range.

In this embodiment, the liquid crystal layer thickness adjusting films 8, and the liquid crystal layer thickness d _R of the red pixel, a liquid crystal layer thickness d _G of the green pixel, and a liquid crystal layer thickness d _B of the blue pixel, respectively, d _R = The liquid crystal layer 11 is formed of a liquid crystal material having a thickness of about 4.2 μm, d _G = about 4.0 μm, d _B = about 3.7 μm, and a refractive index anisotropy Δn of Δn = 0.073. The value of Δn · d _R of the liquid crystal layer 11 of the red pixel is about 306.6 nm, the value of Δn · d _G of the liquid crystal layer 11 of the green pixel is about 292.0 nm, and the liquid crystal layer 11 of the blue pixel is formed. the Δn · _{d B} is set to about 270.1nm.

Note that the liquid crystal layer thicknesses d _R , d _G , and d _B of the red, green, and blue color pixels are the color filters 7R, 7G for the red, green, and blue colors instead of providing the liquid crystal layer thickness adjusting film 8, respectively. , 7B may be set as described above with different thicknesses.

  On the other hand, the first and second polarizing plates 12 and 13 are absorption polarizing plates each having a transmission axis (not shown) and absorption axes 12a and 13a in directions orthogonal to each other. Among them, the polarizing plate 12 on the front side that is the observation side has its absorption axis 12a in a direction of 30 ° (30 ° counterclockwise when viewed from the outer surface side of the front polarizing plate 12) with respect to the horizontal axis x of the screen. The rear polarizing plate 13, which is disposed facing away from the observation side, has an absorption axis 13 a that is 150 ° with respect to the horizontal axis x of the screen (counterclockwise when viewed from the outer surface side of the front polarizing plate 12). At 150 °).

  Although the structure of the first and second discotic liquid crystal films 14 and 15 is not shown in the drawing, the discotic liquid crystal molecules in a disk shape are aligned in one direction and the tilt direction is aligned in one direction. The discotic liquid crystal films 14 and 15 are polymerized so that the tilt angle gradually increases toward the surface, and the discotic liquid crystal films 14 and 15 have a tilt angle of liquid crystal molecules from one film surface side where the tilt angle of liquid crystal molecules is small. Optical tilted obliquely in the direction of the average of the molecular axes of the discotic liquid crystal molecules arranged in the tilted state (the axis perpendicular to the disk-like molecular plane) toward the other film surface side with a large Has an axis.

  In other words, the discotic liquid crystal films 14 and 15 have a direction in which the directions of the molecular axes of the discotic liquid crystal molecules arranged in the tilted state (axis perpendicular to the disc-like molecular plane) are averaged, and the film The liquid crystal molecules having different tilt angles arranged in the thickness direction have tilted optical axes oriented in the direction opposite to the opening direction of the molecular plane spacing.

  The discotic liquid crystal films 14 and 15 have negative optical anisotropy having the smallest refractive index in the direction along the optical axis.

  In FIG. 1, reference numerals 14a and 15a denote on-plane optical axes obtained by projecting the optical axes of the discotic liquid crystal films 14 and 15 onto the film surface.

  Of the first and second discotic liquid crystal films 14 and 15, the front (observation side) discotic liquid crystal film 14 has an on-plane optical axis 14a of 135 ° with respect to the horizontal axis x of the screen. The discotic liquid crystal film 15 on the rear side is arranged in a direction (135 ° counterclockwise when viewed from the outer surface side of the front polarizing plate 12), and the optical disc 15a on the surface thereof has an optical axis 15a on the horizontal axis x of the screen. Are arranged in the direction of −45 ° (45 ° clockwise when viewed from the outer surface side of the front polarizing plate 12).

  The first and second uniaxial phase plates 16 and 17 are made of norbornene resin films, and each of the uniaxial phase plates 16 and 17 has a phase difference of 250 nm to 300 nm, for example, 270 nm. have.

Further, the first and second biaxial phase plates 18 and 19 are made of a polycarbonate resin film, and the direction in which the refractive index on the phase plate surface is the largest is the x axis, and the x on the phase plate surface is the x axis. y-axis and a direction perpendicular to the axial the direction perpendicular to the phase plate surface and the z-axis, the x-axis direction of the refractive index n _x, the y-axis direction of the refractive index n _y, the refractive of the z-axis direction when the rate was _{n z,} these refractive index _{n x, n z, n y} has a characteristic in the relation of _{n x> n z> n y} .

Plane retardation by said x refractive index of the axis of the refractive indices _{n x} and y-axis direction _{n y} and the plate thickness t of the phase plate surfaces of the biaxial phase plate 18, 19 _(n x _-n y) × t are each, range 120Nm～150nm, for example 135 nm, _{and, Nz = (n x -n z} ) / (n x -n y) range value of -0.5 to + 0.3, e.g. It has an Nz coefficient of Nz = 0.15.

  The first and second uniaxial phase plates 16 and 17 and the biaxial phase plates 18 and 19 make the uniaxial phase plates 16 and 17 adjacent to the polarizing plates 12 and 13, respectively. 18 and 19 are arranged adjacent to the discotic liquid crystal films 14 and 15.

  Of the first and second biaxial phase plates 18 and 19, the front biaxial phase plate 18 disposed between the front polarizing plate 12 and the discotic liquid crystal film 14 has a slow phase. The axis 18a is disposed in a direction of 135 ° (135 ° counterclockwise when viewed from the outer surface side of the front polarizing plate 12) with respect to the horizontal axis x of the screen, and the rear polarizing plate 13 and the discotic liquid crystal film The rear biaxial phase plate 19 disposed between the lower polarizing plate 15 and the slow axis 19a is 135 ° with respect to the horizontal axis x of the screen (135 counterclockwise as viewed from the outer surface side of the front polarizing plate 12). °) is oriented toward the direction.

  Of the first and second uniaxial phase plates 16 and 17, the front uniaxial phase plate 16 disposed between the front polarizing plate 12 and the discotic liquid crystal film 14 has a slow axis 16a. Is oriented in the direction of 15 ° (15 ° counterclockwise when viewed from the outer surface side of the front polarizing plate 12) with respect to the horizontal axis x of the screen, and the rear polarizing plate 13 and the discotic liquid crystal film 15 The rear uniaxial phase plate 17 disposed between the slow axis 17a and the horizontal axis x of the screen is 75 ° (75 ° counterclockwise when viewed from the outer surface side of the front polarizing plate 12). It is arranged in the direction.

  Therefore, the optical axes 14a and 15a on the front and rear discotic liquid crystal films 14 and 15 and the slow axes 18a and 19a of the front and rear biaxial phase plates 18 and 19, respectively, It is parallel to the liquid crystal molecule alignment direction (direction along the rubbing directions 2a and 3a of the inner surfaces of the pair of substrates 2 and 3) of the homogeneous alignment type liquid crystal element 1.

The slow axes 16 a and 17 a of the front and rear uniaxial phase plates 16 and 17 and the absorption axes 12 a and 13 a of the front and rear polarizing plates 12 and 13 are the same as those of the front biaxial phase plate 18. The shift angle of the slow axis 16a of the front uniaxial phase plate 16 with respect to the slow axis 18a is φ1, and the slow axis 17a of the rear uniaxial phase plate 17 with respect to the slow axis 19a of the rear biaxial phase plate 19 is The deviation angle is φ2, the deviation angle of the absorption axis 12a of the front polarizing plate 12 with respect to the slow axis 18a of the front biaxial phase plate 18 is θ1, and the rear side of the rear biaxial phase plate 19 with respect to the slow axis 19a. When the shift angle of the absorption axis 13a of the polarizing plate 13 is θ2, and as described above, the counterclockwise angle when viewed from the outer surface side of the front polarizing plate 12 is a positive angle and the clockwise angle is a negative angle. ,
φ1 = 60 °
φ2 = -60 °
θ1 = 135 ° + 2φ1
θ2 = 135 ° + 2φ2
In the direction of

  That is, as shown in FIG. 1, the slow axis 18a of the front biaxial phase plate 18 is in a direction of 135 ° counterclockwise as viewed from the outer surface side of the front polarizing plate 12 with respect to the horizontal axis x of the screen. The slow axis 16a of the front uniaxial phase plate 16 is in the direction of 15 ° counterclockwise when viewed from the outer surface side of the front polarizing plate 12 with respect to the horizontal axis x, and the absorption axis 12a of the front polarizing plate 12 is With respect to the horizontal axis x, it is in the direction of 30 ° counterclockwise as viewed from the outer surface side of the front polarizing plate 12, and the slow axis 19a of the rear biaxial phase plate 19 is in relation to the horizontal axis x. The slow axis 17a of the rear uniaxial phase plate 17 is oriented in a counterclockwise direction of 135 ° when viewed from the outer surface side of the front polarizing plate 12, and from the outer surface side of the front polarizing plate 12 with respect to the horizontal axis x. The absorption axis 13 a of the rear polarizing plate 13 is 75 ° counterclockwise as viewed from the outside of the front polarizing plate 12 with respect to the horizontal axis x. It is in the direction of 150 ° counterclockwise when viewed from the surface side.

  The shift angle φ1 of the slow axis 16a of the front uniaxial phase plate 16 with respect to the slow axis 18a of the front biaxial phase plate 18 and the rear uniaxial phase of the rear biaxial phase plate 19 with respect to the slow axis 19a. The shift angle φ2 of the slow axis 17a of the plate 17 is shifted in the counterclockwise direction with respect to the slow axes 18a and 19a of the biaxial phase plates 18 and 19 when viewed from the outer surface side of the front polarizing plate 12, respectively. It takes a positive value when the slow axes 16a and 17a of the uniaxial phase plates 16 and 17 are present, and is shifted in a clockwise direction with respect to the slow axes 18a and 19a of the biaxial phase plates 18 and 19. If a negative value is assumed when the slow axes 16a and 17a of the uniaxial phase plates 16 and 17 are present, in this embodiment, the slow axis 16a of the front uniaxial phase plate 16 is the front biaxial phase. When viewed from the outer surface side of the front polarizing plate 12 with respect to the slow axis 18a of the plate 18, it is counterclockwise. The slow axis 17 a of the rear uniaxial phase plate 17 is shifted by 60 °, and the slow axis 17 a of the rear biaxial phase plate 19 is 60 ° clockwise when viewed from the outer surface side of the front polarizing plate 12 with respect to the slow axis 19 a of the rear biaxial phase plate 19. Because of the deviation, the deviation angle φ1 of the slow axis 16a of the front uniaxial phase plate 16 with respect to the slow axis 18a of the front biaxial phase plate 18 is 60 °, and the slow phase of the rear biaxial phase plate 19 The deviation angle φ2 of the slow axis 17a of the rear uniaxial phase plate 17 with respect to the axis 19a is −60 °.

Also, the shift angle θ1 of the absorption axis 12a of the front polarizing plate 12 with respect to the slow axis 18a of the front biaxial phase plate 18 and the absorption axis of the rear polarizing plate 13 with respect to the slow axis 19a of the rear biaxial phase plate 19 13a of the polarizing plates 12 and 13 are shifted in the counterclockwise direction with respect to the slow axes 18a and 19a of the biaxial phase plates 18 and 19 when viewed from the outer surface side of the front polarizing plate 12, respectively. When the absorption axes 12a and 13a are present, they take a positive value, and the absorption axes 12a of the polarizing plates 12 and 13 are shifted in the clockwise direction with respect to the slow axes 18a and 19a of the biaxial phase plates 18 and 19. , 13a and take a negative value, in this embodiment, the deviation angle φ1 of the slow axis 16a of the front uniaxial phase plate 16 with respect to the slow axis 18a of the front biaxial phase plate 18 is 60 °, rear side of the rear biaxial phase plate 19 with respect to the slow axis 19a Since the deviation angle φ2 of the slow axis 17a of the uniaxial phase plate 17 is -60 °, the deviation angle θ1 of the absorption axis 12a of the front polarizer 12 for the slow axis 18a of the front biaxial phase plate 18,
θ1 = 135 ° + 2φ1 = 135 ° + 2 × 60 ° = 255 °
The deviation angle θ2 of the absorption axis 13a of the rear polarizing plate 13 with respect to the slow axis 19a of the rear biaxial phase plate 19 is
θ2 = 135 ° + 2φ2 = 135 ° + 2 × (−60 °) = 15 °
It is.

  This liquid crystal display element displays an image by controlling the transmission of light from a surface light source (not shown) disposed on the rear side (the side opposite to the display observation side). In this liquid crystal display element, The biaxial phase plates 18 and 19 correspond to λ / 4 plates that give a phase difference of ¼ wavelength between the ordinary light and the extraordinary light of the transmitted light, and the uniaxial phase plates 16 and 17 are the ordinary light of the transmitted light. Is equivalent to a λ / 2 plate that gives a phase difference of ½ wavelength between the extraordinary light and the extraordinary light, so that the polarizing plate 12, the uniaxial phase plate 16 and the biaxial phase plate 18 on the observation side form a pair. The polarizing plate 13 on the opposite side, the uniaxial phase plate 17 and the biaxial phase plate 19 function as a wide band circular polarizing plate.

  For this reason, in this liquid crystal display element, the light incident as the linearly polarized light in the direction (transmission axis direction) orthogonal to the absorption axis 13a from the rear side polarizing plate 13 from the rear side is incident on the rear uniaxial phase plate 17 and the rear side. The side biaxial phase plate 19 makes the circularly polarized light, which passes through the rear discotic liquid crystal film 15 and enters the homogeneous alignment type liquid crystal element 1.

  When a voltage for aligning the liquid crystal molecules 11a of the liquid crystal layer 11 in the initial homogeneous alignment state is applied between the electrodes 4 and 5 of the plurality of pixels of the homogeneous alignment type liquid crystal element 1, the liquid crystal layer 11 becomes λ / Since the circularly polarized light incident on the liquid crystal element 1 is transmitted through the liquid crystal layer 11, the circularly polarized light enters the liquid crystal element 11 and is emitted from the liquid crystal element 1, and the light (reversely circularly polarized light) is emitted. ) Is transmitted through the front discotic liquid crystal film 14, and is converted into linearly polarized light in the direction (transmission axis direction) perpendicular to the absorption axis 12a of the front polarizing plate 12 by the front biaxial phase plate 18 and the front uniaxial phase plate 16. The light enters the front polarizing plate 12, passes through the front polarizing plate 12, exits to the observation side, and becomes bright display.

  In addition, when a voltage is applied between the electrodes 4 and 5 of the plurality of pixels of the homogeneous alignment type liquid crystal element 1 so that the liquid crystal molecules 11a of the liquid crystal layer 11 rise and align at a predetermined angle with respect to the surfaces of the substrates 2 and 3. The circularly polarized light incident on the liquid crystal element 1 is transmitted through the liquid crystal layer 11 with almost no change in the polarization state and emitted from the liquid crystal element 1, and the circularly polarized light is transmitted through the front discotic liquid crystal film 14 to The biaxial phase plate 18 and the front uniaxial phase plate 16 make the linearly polarized light parallel to the absorption axis 12a of the front polarizing plate 12 and enter the front polarizing plate 12, which is absorbed by the front polarizing plate 12 and becomes black. Is displayed.

  The emitted light from the region corresponding to the pixel to which the bright display voltage is applied of the homogeneous alignment type liquid crystal element 1 is provided on the inner surface of the front substrate 2 of the liquid crystal element 1 so as to correspond to a plurality of pixels, respectively. The three color filters 7R, 7G, and 7B of red, green, and blue are colored light of red, green, and blue, and a full color image is displayed by mixing these colored lights.

  In this liquid crystal display element, discotic liquid crystal films 14 and 15 are respectively disposed between the homogeneous alignment type liquid crystal element 1 and the front and rear polarizing plates 12 and 13 disposed so as to sandwich the liquid crystal element 1. The front-side uniaxial phase plate 16 and the front-side biaxial phase plate 18 are interposed between the observation-side polarizing plate 12 and the discotic liquid crystal film 14, and the opposite-side polarizing plate 13 and the discotic liquid crystal film 15 are interposed. Since the rear uniaxial phase plate 17 and the rear biaxial phase plate 19 are arranged, the front and rear discotic liquid crystal films 14 and 15, the front uniaxial phase plate 16 and the biaxial phase are arranged. Due to the synergistic action of the plate 18 and the uniaxial phase plate 17 and the biaxial phase plate 19 on the rear side, there is no contrast inversion over a wide observation direction and angle, and a high contrast display is obtained. It is possible.

  In the above embodiment, the front and rear uniaxial phase plates 16 and 17 and the biaxial phase plates 18 and 19 are made adjacent to the polarizing plates 12 and 13, and the biaxial phase plates 18 and 19 are made adjacent to each other. Optical phase plates 18 and 19 are disposed adjacent to the discotic liquid crystal films 14 and 15, and on-surface optical axes 14a and 15a obtained by projecting the optical axes of the front and rear discotic liquid crystal films 14 and 15 onto the film surface; The slow axes 18a and 19a of the front and rear biaxial phase plates 18 and 19 are parallel to the liquid crystal molecular alignment direction of the homogeneous alignment type liquid crystal element 1, respectively, and the front and rear uniaxial phase plates are arranged. 16, 17 slow axes 16 a, 17 a and the absorption axes 12 a, 13 a of the front and rear polarizing plates 12, 13 as viewed from the outer surface side of the front polarizing plate 12, a counterclockwise angle is a positive angle , Clockwise angle The angle φ1 of the slow axis 16a of the front uniaxial phase plate 16 with respect to the slow axis 18a of the front biaxial phase plate 18 is 60 ° to 80 °, and the rear biaxial phase plate 19 The deviation angle φ2 of the slow axis 17a of the rear uniaxial phase plate 17 with respect to the slow axis 19a is −60 ° to −80 °, and the absorption of the front polarizing plate 12 with respect to the slow axis 18a of the front biaxial phase plate 18 The deviation angle θ1 of the shaft 12a is set to 135 ° + 2φ1, and the deviation angle θ2 of the absorption axis 13a of the rear polarizing plate 13 with respect to the slow axis 19a of the rear biaxial phase plate 19 is set to 135 ° + 2φ2. Therefore, there is no contrast inversion over a wider viewing direction and viewing angle, and a high-contrast display can be obtained.

Further, in the above embodiment, the phase difference between the front and rear uniaxial phase plates 16 and 17 is in the range of 250 nm to 300 nm, respectively, and the in-plane phase difference between the front and rear biaxial phase plates 18 and 19. were each in the range of 120Nm～150nm, and, Nz coefficient of the front and rear side biaxial phase plate 18, _19, Nz ₌ the value of _{(n x -n z) / (} n x -n y) , respectively Since it is in the range of −0.5 to +0.3, there is no contrast inversion over a wider viewing direction and viewing angle, and a high contrast display can be obtained.

  FIG. 3 shows changes in white display (bright display) luminance and black display (dark display) luminance and changes in contrast depending on the viewing angle in the left-right direction (direction along the horizontal axis x of the screen) of the liquid crystal display element. Indicates changes in white display (bright display) luminance and black display (dark display) luminance and changes in contrast depending on the viewing angle in the vertical direction (direction along the vertical axis of the screen) of the liquid crystal display element. The characteristics are obtained when the homogeneous alignment type liquid crystal element 1 is replaced with a liquid crystal element in which a color filter is omitted and the other configurations are the same.

  3 and 4, the viewing angle is an angle with respect to the normal line of the screen, the positive viewing angle is the right angle with respect to the normal line of the screen, and the negative viewing angle is with respect to the normal line of the screen. The angle in the left direction.

  The liquid crystal display element has sufficiently high white display brightness in the horizontal direction and vertical direction as shown in FIGS. 3A and 4A, and in the horizontal direction as shown in FIGS. 3B and 4B. Since the black display brightness in the vertical direction is sufficiently low, the contrast ratio is particularly high in the front direction, that is, in the vicinity of the viewing angle of 0 °, as shown in FIGS. 3 (c) and 4 (c). A high contrast ratio can be obtained over the azimuth.

  FIG. 5 shows contrast inversion characteristics depending on the viewing angle of the liquid crystal display element. This characteristic is obtained by replacing the homogeneous alignment type liquid crystal element 1 with a liquid crystal element in which the color filter is omitted and the other configuration is the same. This is a characteristic when a gray display voltage is applied between the electrodes 4 and 5 so that the luminance in the front direction is 15% of the white display luminance.

  In FIG. 5, concentric circles are viewing angles with respect to the normal of the screen, and radiation (broken lines) are viewing angle azimuths in the circumferential direction of the screen, the azimuth angle 0 ° is the right direction of the screen, 180 ° is the left direction of the screen, 90 ° Is the upward direction of the screen and 270 ° is the downward direction of the screen.

  The liquid crystal display element has a viewing angle with respect to the normal of the screen, as shown in FIG. 5 in a viewing angle range A in which the intensity of the gray display and the intensity of the black display are reversed, where the brightness in the front direction is 15% of the white display brightness. When the angle becomes close to 80 °, brightness inversion of the gray display and black display occurs in the vicinity of azimuths of 45 °, 135 °, 225 °, and 315 °, and the viewing angle with respect to the normal line of the screen is larger than that. In a small range, that is, a range close to the front direction, there is no luminance reversal between the gray display and the black display.

  Therefore, the liquid crystal display element has no contrast inversion over a wide viewing direction and viewing angle, and can provide a high contrast display.

Further, as described above, the liquid crystal display element includes a red pixel liquid crystal layer thickness d _R corresponding to the red filter 7R of the homogeneous alignment type liquid crystal element 1, and a green pixel liquid crystal layer thickness d corresponding to the green filter 7G. _G and the liquid crystal layer thickness d _B of the blue pixel corresponding to the blue filter 7G are set to d _R = about 4.2 μm, d _G = about 4.0 μm, d _B = about 3.7 μm, respectively, and the liquid crystal layer 11 is formed of a liquid crystal material of Δn = 0.073, the value of Δn · d _R of the liquid crystal layer 11 of the red pixel is about 306.6 nm, and the value of Δn · d _G of the liquid crystal layer 11 of the green pixel is about 292.0Nm, since the set [Delta] n · _{d B} about 270.1nm of the liquid crystal layer 11 of the blue pixel, wherein the liquid crystal device 1 red, green, red transmitted through each color of the pixels of the blue, green, and blue The colored light of other colors loses the band color A black display voltage of the same value is applied between the electrodes 4 and 5 of each pixel of the liquid crystal element 1 to display a sufficiently dark black to display a color image with good hue and high contrast. it can.

  That is, FIG. 6 shows the relationship between the liquid crystal layer thickness d of the liquid crystal display element and the light transmittance, and FIG. 7 shows the relationship between the liquid crystal layer thickness d of the liquid crystal display element and the chromaticity of the transmitted light. The characteristic alignment liquid crystal element 1 is replaced with a liquid crystal element in which the color filter is omitted and the liquid crystal layer thickness d of all the pixels is the same, and the liquid crystal layer is formed of the liquid crystal material of Δn = 0.073. The characteristics are shown.

  The liquid crystal display element has a higher transmittance as the liquid crystal layer thickness d of the liquid crystal element is larger as shown in FIG. 7, but the chromaticity of white display is as shown in FIG. When it is in the vicinity of 4.0 to 4.2 μm, it is close to the achromatic color point, and outside the range, the white display chromaticity is shifted from the achromatic color point, and a band color is generated.

Therefore, in this embodiment, the liquid crystal layer of the green pixel that transmits light in the green wavelength range that is the intermediate wavelength range of the visible light band among the red, green, and blue color pixels of the homogeneous alignment type liquid crystal element 1. The thickness d _G is set to about 4.0 μm corresponding to the thickness of the liquid crystal layer capable of obtaining a white display close to the achromatic point, and the red pixel that transmits light in the red wavelength range which is a long wavelength range of the visible light range is transmitted. about 4.2μm liquid crystal layer thickness d _R, as well as to the liquid crystal layer thickness d _B of about 3.7μm of the blue pixel for transmitting light in the wavelength region of the a short wavelength range of the visible light band blue, the liquid crystal layer 11 Is made of a liquid crystal material of Δn = 0.073, the value of Δn · d _R of the liquid crystal layer 11 of the red pixel is about 306.6 nm, and the value of Δn · d _G of the liquid crystal layer 11 of the green pixel is about 292. .0Nm, about a [Delta] n · _{d B} of the liquid crystal layer 11 of the blue pixel 270.1n It is set to.

  FIG. 8 shows the center wavelength (650 nm) light in the red wavelength region in the region corresponding to the red pixel of the liquid crystal display element, the center wavelength (550 nm) light in the green wavelength region in the region corresponding to the green pixel, and the blue pixel. 4 shows the voltage-transmittance characteristics of light having a center wavelength (450 nm) in the blue wavelength region in the region corresponding to 1. Here, the transmittance observed from the front direction is shown. FIG. 9 is an enlarged view of a portion where the transmittance in FIG. 8 is lowest.

  As shown in FIGS. 8 and 9, the liquid crystal display element has a voltage (a voltage for aligning the liquid crystal molecules 11 a in the initial homogeneous alignment state between the electrodes 4 and 5 of the red, green, and blue pixels of the liquid crystal element 1. In the figure, the transmittance of red, green, and blue colored light when 0 to 1 V is applied is sufficiently high, and the black display voltage (the figure is the same) between the electrodes 4 and 5 of the pixels of each color. Then, the darkness of black display when 3.4 to 3.6 V) is applied is sufficient.

FIG. 10 shows the center wavelength (650 nm) light in the red wavelength region and the center wavelength (550 nm) light in the green wavelength region when the liquid crystal layer 11 of the liquid crystal element 1 is formed of a liquid crystal material having Δn = 0.073. And the relationship between the optimum black display voltage (the voltage at which a sufficiently dark black display can be obtained) and the liquid crystal layer thickness for the central wavelength (450 nm) light in the blue wavelength range, and the red, green and blue Since the relationship between the optimum black display voltage for light and the liquid crystal layer thickness has a difference as shown in the figure, black display of the same value is made between the electrodes 4 and 5 of the red, green and blue pixels of the liquid crystal element 1. In order to make the light transmittance of the regions corresponding to the red, green, and blue color pixels the lowest when a voltage is applied, the liquid crystal layer thickness d _R of the red pixel and the liquid crystal of the green pixel are set. The layer thickness d _G and the liquid crystal layer thickness d _B of the blue pixel are in a relationship of d _R > d _G > d _B , and The liquid crystal layer thickness of the red and green pixels _d R, approximately 0.2μm a difference _{d G,} a liquid crystal layer thickness of the green pixel and the blue pixel _d G, is to the difference of about 0.3μm of _{d B} desirable.

In the liquid crystal display element, as described above, the liquid crystal layer thickness d _G of the green pixel is set to about 4.0 μm corresponding to the liquid crystal layer thickness at which white display close to the achromatic point is obtained, and the liquid crystal layer thickness of the red pixel is set. d _R is about 4.2 μm larger than the liquid crystal layer thickness d _G of the green pixel, and blue liquid crystal layer thickness d _B is about 0.3 μm smaller than the liquid crystal layer thickness d _{G of the} green pixel. Since the thickness is 3.7 μm, the red, green, and blue colored light transmitted through the pixels of the red, green, and blue colors of the liquid crystal element 1 are eliminated from the other colors, and the liquid crystal element 1 A sufficiently dark black display voltage can be displayed by applying the same black display voltage between the electrodes 4 and 5 of each pixel.

In the above embodiment, the liquid crystal layer thicknesses d _R , d _G and d _B of the red, green and blue pixels of the liquid crystal element 1 are set to d _R = about 4.2 μm, d _G = about 4.0 μm, When d _B = about 3.7 μm and the liquid crystal layer 11 is formed of a liquid crystal material having a refractive index anisotropy Δn of Δn = 0.073, the value of Δn · d _R of the liquid crystal layer 11 of the red pixel is about The value of Δn · d _G of the liquid crystal layer 11 of the green pixel is set to about 292.0 nm, and the value of Δn · d _B of the liquid crystal layer 11 of the blue pixel is set to about 270.1 nm. The values of Δn · d _R , Δn · d _G , and Δn · d _B for pixels of green, blue,
255 nm <Δn (550 nm) · d _G <355 nm
−25 nm <Δn (650 nm) · d _R −Δn (550 nm) · d _G <+30 nm
−35 nm <Δn (450 nm) · d _B −Δn (550 nm) · d _G <+10 nm
In this way, the red, green, and blue colored light that has passed through the pixels of the red, green, and blue colors of the liquid crystal element 1 can be eliminated from the other colors. A black display voltage of the same value is applied between the electrodes 4 and 5 of each pixel of the liquid crystal element 1 to display a sufficiently dark black to display a color image with good hue and high contrast. it can.

  Moreover, in the said Example, the surface optical axes 14a and 15a which projected the optical axis of the front and back discotic liquid crystal films 14 and 15 on the film surface, and the front and back biaxial phase plates 18 and 19 The slow axes 18a and 19a along the direction in which the refractive index is the largest on the phase plate surface of each of the phase plate surfaces are parallel to the liquid crystal molecule alignment direction of the homogeneous alignment type liquid crystal element 1, but these are parallel at about ± 5 °. Differences in degrees are acceptable.

  Further, in the above embodiment, the shift angle φ1 of the slow axis 16a of the front uniaxial phase plate 16 with respect to the slow axis 18a of the front biaxial phase plate 18 and the slow axis 19a of the rear biaxial phase plate 19 are set. The shift angle φ2 of the slow axis 17a of the rear uniaxial phase plate 17 is set to φ1 = 60 ° and φ2 = −60 °, but these shift angles φ1 and φ2 are φ1 = 60 ° to 80 °. , Φ2 = −60 ° to −80 °, and in this way, there is no contrast inversion over a sufficiently wide viewing direction and viewing angle, and a high-contrast display can be obtained.

In the above embodiment, the counterclockwise angle when viewed from the outer surface side of the front polarizing plate 12 is a positive angle and the clockwise angle is a negative angle, but conversely, the outer surface side of the rear polarizing plate 13. The counterclockwise angle may be a positive angle and the clockwise angle may be a negative angle. In this case as well, the slow phase of the front uniaxial phase plate 16 relative to the slow axis 18a of the front biaxial phase plate 18 may be used. The deviation angle φ1 of the shaft 16a, the deviation angle φ2 of the slow axis 17a of the rear uniaxial phase plate 17 with respect to the slow axis 19a of the rear biaxial phase plate 19, and the delay of the front biaxial phase plate 18 A deviation angle θ1 of the absorption axis 12a of the front polarizing plate 12 with respect to the phase axis 18a and a deviation angle θ2 of the absorption axis 13a of the rear polarizing plate 13 with respect to the slow axis 19a of the rear biaxial phase plate 19 are
φ1 = 60 °
φ2 = -60 °
θ1 = 135 ° + 2φ1
θ2 = 135 ° + 2φ2
The same effect as in the above embodiment can be obtained by setting the direction as described above.

  Further, in the above embodiment, the upper side in FIGS. 1 and 2 is the observation side, but on the contrary, the lower side in FIGS. 1 and 2 may be the observation side. Obtainable.

  DESCRIPTION OF SYMBOLS 1 ... Homogeneous alignment type liquid crystal element, 2, 3 ... Substrate, 2a, 3a ... Rubbing direction, 4, 5 ... Electrode, 6 ... TFT, 7R, 7G, 7B ... Color filter, 11 ... Liquid crystal layer, 11a ... Liquid crystal molecule, DESCRIPTION OF SYMBOLS 12, 13 ... Polarizing plate, 12a, 13a ... Absorption axis, 14, 15 ... Discotic liquid crystal film, 14a, 15a ... On-plane optical axis, 16, 17 ... Uniaxial phase plate, 16a, 17a ... Slow axis, 18 , 19 ... biaxial phase plate, 18a, 19a ... slow axis.

Claims (6)

Homogeneous alignment liquid crystal layer of the non-twist aligned homogeneously the liquid crystal molecules align the molecular long axis in one direction to each opposite to that surface of the pair of substrates sandwiching a plurality of pixels arranged in a matrix by region facing each other A homogeneous alignment type liquid crystal element that changes the polarization state of transmitted light by controlling the rising angle of the liquid crystal molecules of the liquid crystal layer with respect to the substrate surface by applying a voltage between the electrodes; and
First and second discotic liquid crystal films sandwiching the homogeneous alignment type liquid crystal element ;
First and second biaxial phase plates sandwiching the first and second discotic liquid crystal films;
First and second uniaxial phase plates sandwiching the first and second biaxial phase plates;
First and second polarizing plates sandwiching the first and second uniaxial phase plates;
A surface light source on the outer surface side of one of the first and second polarizing plates;
A liquid crystal display element comprising: Projecting the slow axis along the direction in which the refractive index is largest on the phase plate surface of the first and second biaxial phase plates and the optical axis of the first and second discotic liquid crystal films onto the film surface And the surface optical axis is parallel to the liquid crystal molecule alignment direction of the adjacent homogeneous liquid crystal element,
The deviation angle of the slow axis of said first uniaxial phase plate to the previous SL slow axis of the first biaxial phase plate .phi.1, the second for the slow axis of the second biaxial phase plate The angle of deviation of the slow axis of the uniaxial phase plate is φ2, the angle of deviation of the absorption axis of the first polarizing plate with respect to the slow axis of the first biaxial phase plate is θ1, and the second biaxial The angle of deviation of the absorption axis of the second polarizing plate with respect to the slow axis of the phase-difference phase plate is θ2, and the outer surface side of one of the first and second polarizing plates on the side opposite to the surface light source When the counterclockwise angle is a positive angle and the clockwise angle is a negative angle,
The direction of the slow axis of the first and second uniaxial phase plates and the direction of the absorption axis of the first and second polarizing plates are:
φ1 = 60 ° -80 °
φ2 = -60 ° ~ -80 °
θ1 = 135 ° + 2φ1
θ2 = 135 ° + 2φ2
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is set in a direction. It said first and have a phase difference of ranges of the second uniaxial phase plate 250-300 nm, the range of the first and second biaxial phase plate respectively is 1 20 nm to 150 nm The direction having the in-plane phase difference and having the largest refractive index on the phase plate surface is the x axis, the direction perpendicular to the x axis on the phase plate surface is the y axis, and the direction perpendicular to the phase plate surface is z. as an axis, when the x-axis direction of the refractive index n _x, the y-axis direction of the refractive index n _y, the refractive index of the z-axis direction is n _{z,
Nz = (n x -n z)} / (n x -n y)
3. The liquid crystal display element according to claim 2, having a Nz coefficient in a range of −0.5 to +0.3. On either side of the pair of substrates facing the homogeneous alignment liquid crystal element, red corresponding to a plurality of pixels, a green color filter of three colors of blue are provided, the plurality of pixels Among them, the value of the product Δn · d of the refractive index anisotropy Δn and the liquid crystal layer thickness d of the liquid crystal of the pixel corresponding to the red filter, the pixel corresponding to the green filter, and the pixel corresponding to the blue filter is the liquid crystal layer thickness of the pixel corresponding to the red filter d _R, the liquid crystal layer thickness of d _G of the pixels corresponding to the green _filter, a liquid crystal layer thickness of the pixel corresponding to the blue filter and d _B, the liquid crystal refractive index different When the values of the directivity Δn with respect to light of each wavelength of 650 nm, 550 nm, and 450 nm are Δn (650 nm), Δn (550 nm), and Δn (450 nm), respectively.
255 nm <Δn (550 nm) · d _G <355 nm
−25 nm <Δn (650 nm) · d _R −Δn (550 nm) · d _G <+30 nm
−35 nm <Δn (450 nm) · d _B −Δn (550 nm) · d _G <+10 nm
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is set in a range of In the first and second discotic liquid crystal films, disc-like discotic liquid crystal molecules are aligned in one direction and the tilt angle gradually increases from one surface to the other. The discotic liquid crystal is arranged in the tilted state from one film surface side where the tilt angle of liquid crystal molecules is small toward the other film surface side where the tilt angle of liquid crystal molecules is large. It has an inclined optical axis inclined obliquely in a direction averaged with respect to the molecular axis of the molecule, that is, the direction perpendicular to the disc-like molecular plane, and the refractive index in the direction along the inclined optical axis is the smallest The liquid crystal display element according to claim 1, which has negative optical anisotropy. The polarizing plate on the surface light source side, the uniaxial phase plate, and the biaxial phase plate function as a wide band circular polarizing plate, and the polarizing plate on the side opposite to the surface light source and the The uniaxial phase plate and the biaxial phase plate function as a wide-band circularly polarizing plate, and the homogeneously aligned liquid crystal element is a λ / 2 plate that gives a half-wave phase difference The liquid crystal display element according to claim 1, wherein the liquid crystal display element functions as an optical element that switches between voltage and a state in which no phase difference is given.

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