JP5194685B2 - Liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal display element that performs reflective display.

A liquid crystal display element for performing reflective display includes a liquid crystal layer sealed between a pair of substrates on the observation side and the opposite side, and a polarizing plate disposed on at least the outer surface side of the substrate on the observation side of the pair of substrates And a reflective film that is disposed on the opposite side of the liquid crystal layer and reflects light incident from the observation side (see Patent Document 1).
JP-A-8-179382

  The liquid crystal display element that performs the reflective display reflects light incident from the observation side by the reflective film and emits the reflected light to the observation side for display, so that the light incident from the observation side reciprocates the liquid crystal layer. Then penetrate.

Therefore, in the liquid crystal display element, due to the wavelength dispersion action of the liquid crystal layer, the difference in the polarization state of the light that is transmitted through the liquid crystal layer and incident on the polarizing plate on the observation side becomes large. transmitted through the polarizing plate at different transmittance and. As a result, a band color is generated in the light emitted to the observation side.

  An object of the present invention is to provide a liquid crystal display element capable of performing a reflective display in which a band color is hardly noticeable.

In order to achieve the above-described object, one aspect of the liquid crystal display element of the present invention is a liquid crystal layer sealed between a first substrate and a second substrate facing each other, and the first liquid crystal layer provided on the observation side . a polarizing plate disposed on a surface different from the first surface facing the liquid crystal layer of the substrate are arranged as a plurality of pixel electrodes on the surface facing the liquid crystal layer of said second substrate, incident from the observation side A reflection film that reflects the reflected light, and a wavelength range that is disposed closer to the observation side than the reflection film, and that colors the light incident from the observation side, reflected by the reflection film, and emitted to the observation side A liquid-crystal compensation layer having a light absorption region, the liquid crystal of the liquid crystal layer is a nematic liquid crystal, and the liquid crystal molecules are between 60 ° and 70 ° between the first substrate and the second substrate. Twist angle and twist orientation The filter includes a dye filter in which a dye having a color in a wavelength region corresponding to the light absorption region is dispersed, has an absorption characteristic having an absorption peak in a wavelength region of 570 nm to 580 nm, and the first substrate. The pigment filter is a pressure-sensitive adhesive layer in which the pigment is dispersed, or a film in which the pigment is dispersed in a transparent film .

  According to the liquid crystal display element of the present invention, it is possible to perform a reflective display in which the band color is hardly noticeable.

(First embodiment)
FIG. 1 is a cross-sectional view of a part of a liquid crystal display device showing a first embodiment of the present invention.

  The liquid crystal display element of this embodiment is a reflective liquid crystal display element that performs only reflective display, and a liquid crystal layer 3 sealed between a pair of substrates 1 and 2 on the observation side (upper side in the figure) and the opposite side; One polarizing plate 9 disposed only on the outer surface side (the surface side facing the observation side) of the observation side substrate (hereinafter referred to as the front substrate) 1 of the pair of substrates 1 and 2, and the liquid crystal A reflective film 11 that is disposed on the opposite side of the observation side from the layer 3 and reflects light incident from the observation side, and a band color compensation filter 15 that is disposed on the observation side of the reflection film 11. I have.

  This liquid crystal display element is an active matrix liquid crystal display element using TFTs (thin film transistors) as active elements, and is one of inner surfaces facing each other of the pair of substrates 1 and 2, for example, a substrate opposite to the observation side (hereinafter referred to as “observation side”). A plurality of pixel electrodes 4 formed in a matrix in the row direction and the column direction and a plurality of TFTs 5 respectively disposed corresponding to these pixel electrodes 4 are provided on the inner surface of 2) (referred to as a rear substrate). On the other substrate, that is, on the inner surface of the front substrate 1, a single-layered counter electrode 6 that is opposed to the plurality of pixel electrodes 4 is provided.

  Although the TFT 5 is simplified in FIG. 1, the TFT 5 includes a gate electrode formed on the rear substrate 2, a gate insulating film formed so as to cover the gate electrode, and the gate insulating film. An i-type semiconductor film is formed on the gate electrode opposite to the gate electrode, and a source electrode and a drain electrode are formed on both sides of the i-type semiconductor film via an n-type semiconductor film.

  The gate insulating film is formed over substantially the entire inner surface of the rear substrate 2, and the plurality of pixel electrodes 4 are formed on the gate insulating film, and the plurality of pixel electrodes 4 corresponding to the pixel electrodes 4 are formed. Each is connected to the source electrode of the TFT 5.

Further, although omitted in FIG. 1, on the inner surface of the rear substrate 2, a plurality of scanning lines for supplying gate signals to the TFTs 5 in each row and a plurality of signals for supplying data signals to the TFTs 5 in each column are provided. The plurality of scanning lines are respectively connected to the gate electrodes of the plurality of TFTs 5 in each row, and the plurality of signal lines are respectively connected to the drain electrodes of the plurality of TFTs 5 in each column. .

  The plurality of pixel electrodes 4 are made of a metal film having high light reflectivity, such as an aluminum film, for example, and a reflection film 11 that reflects light incident from the observation side is formed by the pixel electrodes 4. Yes.

  At least the front substrate 1 of the pair of substrates 1 and 2 is a transparent substrate made of glass or the like, and the counter electrode 6 formed on the inner surface of the front substrate 1 is a transparent conductive film such as an ITO film. It is formed by.

  In addition, transparent alignment films 7 and 8 are formed on the inner surfaces of the pair of substrates 1 and 2 so as to cover the electrodes 4 and 6, respectively. Each of the film surfaces 8 is rubbed to be oriented.

The pair of substrates 1 and 2 are arranged to face each other with a predetermined gap, and are joined via a frame-shaped sealing material (not shown) surrounding the array region of the plurality of pixel electrodes 4. A liquid crystal layer 3 is formed by sealing a liquid crystal made of nematic liquid crystal in a region surrounded by the sealing material between the substrates 1 and 2.

  The liquid crystal molecules of the liquid crystal layer 3 have their molecular long axes oriented in the vicinity of the substrates 1 and 2 by the alignment treatment of the pair of substrates 1 and 2, and are predetermined between the pair of substrates 1 and 2. In the initial alignment state.

  This liquid crystal display element is a TN type liquid crystal display element in which the liquid crystal molecules of the liquid crystal layer 3 are twist-oriented between the pair of substrates 1 and 2 at a twist angle of 60 ° to 70 °, and the polarizing plate 9 includes: The transmission axis is arranged so as to intersect the orientation direction of the liquid crystal molecules in the vicinity of the front substrate 1 at an angle of 105 ° to 110 ° in the direction opposite to the twist direction of the liquid crystal molecules.

  In addition, when the liquid crystal layer 3 has no electric field (when the liquid crystal molecules are in a twist alignment state with a twist angle of 60 ° to 70 °), the product Δnd of the birefringence Δn of the liquid crystal and the liquid crystal layer thickness d is 210 nm to It is set to 240 nm.

  Further, the liquid crystal display element performs a normally white display in which no electric field is displayed in white, so that the broadband retardation layer 12 that gives a quarter-wave phase difference to wavelength light in the entire visible light band. It has.

  The broadband retardation layer 12 is formed by laminating a λ / 4 retardation plate 13 and a λ / 2 retardation plate 14 with their slow axes intersecting at a predetermined angle. 1 and the polarizing plate 9, for example, the λ / 4 retardation plate 13 is disposed to face the front substrate 1, and the λ / 2 retardation plate 14 is disposed to face the polarizing plate 9. .

  2 shows the alignment processing direction of the pair of substrates 1 and 2 (the rubbing direction of the alignment films 7 and 8), the direction of the transmission axis of the polarizing plate 9 disposed on the outer surface side of the front substrate 1, and the broadband. It is a figure which shows direction of the slow axis of (lambda) / 4 phase difference plate 13 and (lambda) / 2 phase difference plate 14 which comprises the phase difference layer 12, Here, the example which made the twist angle of the said liquid crystal molecule 70 degrees Show.

  As shown in FIG. 2, the front substrate 1 is oriented in a direction 1a of 55 ° counterclockwise with respect to the horizontal axis S of the screen of the liquid crystal display element, and the rear substrate 2 is The liquid crystal molecules of the liquid crystal layer 3 are aligned in the direction 2a of 55 ° clockwise as viewed from the observation side with respect to the horizontal axis S. As indicated by the broken line in the twist direction, the twist direction is 70 degrees from the rear substrate 2 toward the front substrate 1 and in the right direction when viewed from the observation side.

  The polarizing plate 9 has its transmission axis 9a counterclockwise with respect to the horizontal axis S as viewed from the observation side, ie, 165 ° ± 5 °, that is, the liquid crystal molecules in the vicinity of the front substrate 1. With respect to the alignment direction (alignment processing direction of the front substrate 1) 1a, the angle is 110 ° ± 5 ° in the opposite direction (counterclockwise direction as viewed from the observation side) to the twist direction of the liquid crystal molecules as viewed from the observation side. It is arranged to intersect.

  The value of Δnd of the liquid crystal layer 3 is set to 230 nm to 240 nm. In this embodiment, Δn of liquid crystal is 0.073, liquid crystal layer thickness d is 3.2 μm, and the value of Δnd is set to 233.6 nm.

  As described above, when the twist angle of the liquid crystal molecules is 70 ° and the Δnd value of the liquid crystal layer 3 is 230 nm to 240 nm, the broadband retardation layer 12 has a retardation value of λ / 4 retardation of 110 nm to 130 nm. The plate 13 and the λ / 2 phase difference plate 14 having a retardation value of 260 nm to 280 nm are configured.

Then, as shown in FIG. 2, the front substrate 1 side of the lambda / 4 phase difference plate 13, the slow axis 13a, the horizontal axis S with respect to 9 0 ° direction, that is, the front of the substrate 1 Arranged at an angle of 35 ° ± 5 ° with respect to the alignment direction 1a of the liquid crystal molecules in the vicinity in the direction opposite to the twist direction of the liquid crystal molecules as viewed from the observation side (counterclockwise direction as viewed from the observation side). The λ / 2 phase difference plate 14 on the polarizing plate 9 side has a slow axis 14a in the direction of 150 ° ± 5 ° counterclockwise as viewed from the observation side with respect to the horizontal axis S, that is, An angle of 60 ° ± 5 ° with respect to the slow axis 13a of the λ / 4 retardation plate 13 in a direction opposite to the twist direction of the liquid crystal molecules as viewed from the observation side (counterclockwise direction as viewed from the observation side). It is arranged by crossing.

  FIG. 2 shows an example in which the twist angle of the liquid crystal molecules is set to 70 °. However, when the twist angle of the liquid crystal molecules is set to 60 °, the alignment treatment direction 1a of the front substrate 1 and the rear substrate 2 is illustrated. , 2a are set to a direction of 60 ° with respect to the horizontal axis S, and the transmission axis 9a of the polarizing plate 9 is twisted in the liquid crystal molecules with respect to the alignment direction 1a of the liquid crystal molecules in the vicinity of the front substrate 1. Is crossed at an angle of 110 ° ± 5 ° in the opposite direction (counterclockwise as viewed from the observation side), and the value of Δnd of the liquid crystal layer 3 is set to 210 nm to 230 nm.

  As described above, when the twist angle of the liquid crystal molecules is 60 ° and the Δnd value of the liquid crystal layer 3 is 210 nm to 230 nm, the λ / 4 retardation plate 13 and the λ / The retardation value of the λ / 4 retardation plate 13 of the two retardation plates 14 is set to 100 nm to 120 nm (the retardation value of the λ / 2 retardation plate 14 may be 260 nm to 280 nm), and the λ / 4 retardation plate 13 and the direction of the slow axes 13a and 14a of the λ / 2 phase difference plate 14 are set in the same direction as in FIG.

  In this case, the slow axis 13a of the λ / 4 retardation plate 13 on the front substrate 1 side is the liquid crystal molecule viewed from the observation side with respect to the alignment direction 1a of the liquid crystal molecules in the vicinity of the front substrate 1. It intersects with the angle 40 ° ± 5 ° in the opposite direction (counterclockwise as viewed from the observation side) to the twist direction.

Further, when the twist angle of the liquid crystal molecules is set to another angle in the range of 60 ° to 70 °, for example, 65 °, the alignment treatment directions 1a and 2a of the front substrate 1 and the rear substrate 2 and the polarizing plate 9 The direction of the transmission axis 9a, the value of Δnd of the liquid crystal layer 3, and the retardation value of the λ / 4 phase difference plate 13 of the broadband retardation layer 12 are respectively 60 ° twist and 70 ° twist . And the direction of the slow axes 13a and 14a of the λ / 4 phase difference plate 13 and the λ / 2 phase difference plate 14 of the broadband phase difference layer 12 are set in the same direction as in FIG. .

  On the other hand, the band color compensation filter 15 has an absorption characteristic having a light absorption band corresponding to a wavelength band for coloring light incident from the observation side, reflected by the reflective film 11 and emitted to the observation side. doing.

  The intensity of each wavelength light incident from the observation side, reflected by the reflective film 11 and emitted to the observation side is determined by the twist angle of the liquid crystal molecules, the Δnd value of the liquid crystal layer 3, and the transmission of the polarizing plate 9. Corresponding to the direction of the axis 9a, as described above, the twist angle of the liquid crystal molecules is set to 60 ° to 70 °, the Δnd value of the liquid crystal layer 3 is set to 210 nm to 240 nm, and the direction of the transmission axis 9a of the polarizing plate 9 2 is set as shown in FIG. 2, light in a wavelength range of 570 nm to 580 nm is emitted to the observation side with the highest intensity.

Therefore, in this embodiment, the band color compensation filter 15 has an absorption peak in the wavelength range of 570 nm to 580 nm, and the transmittance of the light of the wavelength of 570 nm to 580 nm is 75% to 80%, 550 nm. below and 590nm or more wavelength light transmittance includes those having respectively been 90% or more absorption characteristics.

FIG. 3 is a spectral characteristic diagram of the band-color compensation filter 15. The band-color compensation filter 15 has a transmittance of light having a wavelength of 570 nm to 580 nm, which is the peak of the absorptivity, of 75% to 80%, 550 nm or less, and in 590nm or more wavelength light transmittance respectively are 90% or more, further, 480 nm or less and 600nm or more wavelength light transmittance has its respectively per 100% of the absorption properties.

  The band color compensation filter 15 is a dye filter in which a dye having a color in a wavelength region corresponding to the absorption peak is dispersed, for example, an adhesive layer in which the dye is dispersed, or a transparent in which the dye is dispersed. It is made of a film and is disposed on the observation side of the reflective film 11, for example, between the front substrate 1 and the broadband retardation layer 12.

  In this embodiment, the band color compensation filter 15 is formed of an adhesive layer in which a pigment is dispersed, and the front substrate 1 and the broadband retardation layer 12 are pasted through the band color compensation filter 15. Yes.

  This liquid crystal display element performs reflective display using external light, which is light from the external environment, and reflects light incident from the observation side by the reflective film 11 composed of the plurality of pixel electrodes 4, and the reflected light. Is emitted to the observation side and displayed.

That is, light incident from the observation side, wherein the polarizing plate 9 is linearly polarized, is reflected by the reflective film 11 is controlled polarization state by birefringence effect of the liquid crystal layer 3. Then, the light reflected by the reflective film 11 is further controlled in polarization state by the birefringence action of the liquid crystal layer 3 and enters the polarizing plate 9, and linearly polarized light parallel to the transmission axis 9 a of the polarizing plate 9. The component light passes through the polarizing plate 9 and exits to the observation side.

The liquid crystal display device, since before a reflective liquid crystal display elements arranged one polarizing plate 9 on the outer surface side of the substrate 1, the absorption of light by the polarizer 9, the linear light incident from the observation side Since only absorption for polarization is performed, a bright normally white reflective display can be performed.

  The liquid crystal display element absorbs light corresponding to a wavelength band that colors light incident on the observation side of the reflection film 11 from the observation side and reflected by the reflection film 11 and emitted to the observation side. Since the band color compensation filter 15 having a band is disposed, a reflective display in which the band color is hardly noticeable can be performed.

  That is, in a liquid crystal display element that performs reflective display, light incident from the observation side passes back and forth through the liquid crystal layer 3, and light in a wavelength band of 500 nm to 600 nm is polarized on the observation side due to the wavelength dispersion action of the liquid crystal. Light that is not colored by absorbing light from the band that leaks from the plate to the observation side, but is absorbed by a band color compensation filter that has light absorption characteristics in the wavelength band. Is emitted to the observation side.

  In addition, the wavelength dispersion action of the liquid crystal in the TN liquid crystal display element is larger as the liquid crystal molecules are in the initial twist alignment state.

  As a comparative reference example, the twist angle of the liquid crystal molecules is set to 60 ° to 70 °, the Δnd value of the liquid crystal layer 3 is set to 210 nm to 240 nm, the transmission axis 9a of the polarizing plate 9 is set in the direction shown in FIG. When the color compensation filter is not used, light in a wavelength region of 570 nm to 580 nm is emitted to the observation side, and thus white display is light yellow to light yellow green.

  On the other hand, in the liquid crystal display element of this embodiment, the light incident from the observation side, reflected by the reflection film 11 and emitted to the observation side is absorbed by the band-color compensation filter 15, so that the liquid crystal Therefore, it is possible to cancel the band color of the emitted light due to the wavelength dispersion action of the light and perform a reflective display with a small band color.

  FIG. 4 does not include the band color compensation filter 15, but otherwise includes the reflective liquid crystal display element LCD-1 having the same configuration as the liquid crystal display element of the above embodiment, and the above embodiment including the band color compensation filter 15. FIG. 6 is a CIE chromaticity diagram showing white display chromaticity of each of the reflective liquid crystal display elements LCD-2, and shows the chromaticity when the twist angle of liquid crystal molecules is set to 70 °.

  As shown in FIG. 4, the chromaticity (x, y coordinate value) of white display when the twist angle of the liquid crystal molecules of the LCD-1 is 70 ° is x = 0.310 and y = 0.332. The color difference ΔW with respect to the achromatic color point W (x = 0.310, y = 0.316) is as large as ΔW = 0.016.

  On the other hand, when the twist angle of the LCD-2 is 70 °, the chromaticity of white display is x = 0.305, y = 0.319, and the color difference ΔW with respect to the achromatic color point W is ΔW = 0.006 and small. This is the same when the twist angle of the liquid crystal molecules is set to 60 ° to 70 °. In any of the twist angles, white display with a small color difference ΔW with respect to the achromatic color point W is obtained.

  As described above, the liquid crystal display element LCD-2 of the above embodiment can provide a white display with a small color difference ΔW with respect to the achromatic color point W, and therefore can perform a high-quality reflective display in which the band color is hardly noticeable.

  In the above-described embodiment, the band color compensation filter 15 is disposed between the front substrate 1 and the broadband phase difference layer 12, and the band color compensation filter 15 includes the broadband phase difference layer 12 and the polarization layer. It may be arranged between the plate 9.

  In the above embodiment, a plurality of pixel electrodes 4 arranged in a matrix on the inner surface of the rear substrate 2 are formed of a metal film, and the plurality of pixel electrodes 4 also serve as the reflection film 11. The plurality of pixel electrodes 4 may be formed of a transparent conductive film, and a reflective film made of a metal film may be provided on the rear side of the plurality of pixel electrodes 4 as a reflective film that reflects light incident from the observation side. Good.

  In that case, the reflective film may be provided on the inner surface of the rear substrate 2, or the rear substrate 2 may be a transparent substrate and provided on the outer surface side of the rear substrate 2, and the reflective film may be provided on the outer surface side of the rear substrate 2. When provided, a band color compensation filter 15 may be disposed between the rear substrate 2 and the reflective film.

(Second Embodiment)
FIG. 5 is a cross-sectional view of a part of a liquid crystal display device showing a second embodiment of the present invention. Incidentally, in this embodiment, the one corresponding to the first embodiment described above are denoted by the same reference numerals in the figures, for those same will be omitted.

  The liquid crystal display element of this embodiment is a reflective / transmissive liquid crystal display element that performs reflective display and transmissive display, and includes a liquid crystal layer 3 sealed between a pair of transparent substrates 1 and 2 on the observation side and the opposite side. A pair of polarizing plates 9 and 10 disposed on the outer surface side of the pair of substrates 1 and 2, respectively, and a transflective film 16 disposed on the outer surface side of the polarizing plate 10 opposite to the observation side, A band color compensation filter 17 disposed on the observation side with respect to the transflective film 16 is provided.

  This liquid crystal display element is an active matrix liquid crystal display element using TFT as an active element, and is provided on one of inner surfaces of the pair of substrates 1 and 2 facing each other, for example, a rear substrate (a substrate opposite to the observation side) 2. Provided on the inner surface are a plurality of transparent pixel electrodes 4 arranged in a matrix in the row direction and the column direction, and a plurality of TFTs 5 arranged corresponding to these pixel electrodes 4 respectively, and the other substrate That is, on the inner surface of the front substrate (observation-side substrate) 1, a single film-like transparent counter electrode 6 that is opposed to the plurality of pixel electrodes 4 is provided.

  Further, alignment films 7 and 8 are formed on the inner surfaces of the pair of substrates 1 and 2 so as to cover the electrodes 4 and 6, respectively, and the inner surfaces of these substrates 1 and 2 are formed on the alignment films 7 and 8. Orientation treatment is performed by rubbing each film surface.

The liquid crystal display device of this embodiment is the liquid crystal layer 3 TN-type liquid crystal display device is twisted in the twist angle of the liquid crystal molecules Te said pair of substrates 1 and 2 between odor 9 0 ° of the liquid crystal layer 3 the value of Δnd is set to 510Nm～630nm, the pair of polarizing plates 9 and 10, in order to display when no electric field makes a normally white display in white, are perpendicular to each of the transmission axis to each other physician Are arranged.

FIG. 6 is a diagram showing the alignment treatment direction of the pair of substrates 1 and 2 (the rubbing direction of the alignment films 7 and 8) and the directions of the transmission axes of the front-side polarizing plate 9 and the rear-side polarizing plate 10. The substrate 1 is oriented in a direction 1a of 45 ° clockwise as viewed from the viewing side with respect to the horizontal axis S of the screen of the liquid crystal display element, and the rear substrate 2 is viewed from the viewing side with respect to the horizontal axis S. The liquid crystal molecules of the liquid crystal layer 3 are aligned in the direction 2a of 45 ° counterclockwise as viewed in the figure, and the twist direction of the liquid crystal molecules between the pair of substrates 1 and 2 is indicated by a broken line. In addition, the orientation is twisted at a twist angle of 90 ° from the rear substrate 2 toward the front substrate 1 and in the leftward direction when viewed from the observation side.

The observation-side polarizing plate (hereinafter referred to as the front polarizing plate) 9 of the pair of polarizing plates 9 and 10 has its transmission axis 9a with the orientation direction of the liquid crystal molecules in the vicinity of the front substrate 1 (front substrate). or the alignment treatment directions) 1a and the flat line of 1, walk is arranged so interlinked straight, opposite side of the polarizing plate and the viewing side (hereinafter, the rear polarizing plate hereinafter) 10, the transmission axis 10a are arranged the transmission axes 9a and allowed direct interlinked of the front polarizer 9.

  On the other hand, the band color compensation filter 17 has a light absorption band corresponding to a wavelength band that colors light incident from the observation side, reflected by the semi-transmissive reflection film 16 and emitted to the observation side.

The intensity of each wavelength light incident from the observation side, reflected by the transflective film 16 and emitted to the observation side corresponds to the twist angle of the liquid crystal molecules and the value of Δnd of the liquid crystal layer 3, and the liquid crystal When the twist angle of the molecule is set to 90 ° and the Δnd value of the liquid crystal layer 3 is set to 510 nm to 630 nm, light in the wavelength range of 540 nm to 560 nm is emitted to the observation side.

Therefore, in this embodiment, the band-color compensation filter 17 has an absorption peak in the wavelength region of 540 nm to 560 nm, and the transmittance of light having the wavelength of 540 nm to 560 nm is 80% to 90%, 470 nm. below and 630nm or more wavelength light transmittance includes those having respectively been 90% or more absorption characteristics.

  In this embodiment, the band color compensation filter 17 is a filter (hereinafter referred to as filter A) having a transmittance of light having a wavelength of 540 nm to 560 nm, which is the peak of the absorption rate, of 85% to 90%. Any of filters (hereinafter referred to as filter B) having a transmittance of light having a wavelength of 540 nm to 560 nm of 80% to 85% is selectively used.

FIG. 7 is a spectral characteristic diagram of the two filters A and B. In the filter A, the transmittance of light having a wavelength of 540 nm to 560 nm, which is the peak of the absorptance, is 85% to 90%, 470 nm or less, and 630 nm or more. in transmittance at a wavelength of light respectively are 90% or more, further, 450 nm or less of the transmittance of the wavelength is 95% or less, the transmittance of 650nm or more wavelength light has an absorption characteristic of 1 100% ing.

Further, the filter B is 80% to 85% of wavelength light transmittance of the a peak of the absorption rate 540Nm～560nm, at 470nm or less and 630nm or more wavelength light transmittance respectively are 90% or more Furthermore, it has an absorption characteristic in which the transmittance of light having a wavelength of 450 nm or less is 95% or less and the transmittance of light having a wavelength of 650 nm or more is 100 %.

  The band color compensation filter 17 is a pigment filter in which a pigment having a color in a wavelength region corresponding to the absorption peak is dispersed in a transparent material, for example, an adhesive layer in which the pigment is dispersed, or the pigment Is disposed on the observation side of the transflective film 16, for example, between the rear substrate 2 and the rear polarizing plate 10.

  In this embodiment, the band color compensation filter 17 is formed of an adhesive layer in which a pigment is dispersed, and the rear substrate 2 and the rear polarizing plate 10 are pasted through the band color compensation filter 17. Yes.

  Further, a diffusion layer 18 for diffusing transmitted light is disposed between the rear polarizing plate 10 and the transflective film 16 on the outer surface side thereof. The diffusion layer 18 is made of, for example, a pressure-sensitive adhesive layer in which light scattering particles are dispersed, and the rear polarizing plate 10 and the transflective film 16 are attached via the diffusion layer 18.

  This liquid crystal display element performs a reflective display using external light and a transmissive display using illumination light from a surface light source (not shown) disposed on the rear side of the liquid crystal display element. The light incident from the observation side is linearly polarized by the front polarizing plate 9, the polarization state is controlled by the birefringence action of the liquid crystal layer 3, and enters the rear polarizing plate 10. Light having a linearly polarized component parallel to the transmission axis 10 a is transmitted through the rear polarizing plate 10 and reflected by the semi-transmissive reflective film 16. Then, the light reflected by the transflective film 16 is transmitted again through the rear polarizing plate 10 and is incident on the front polarizing plate 9 with its polarization state controlled by the birefringence of the liquid crystal layer 3. The light of the linearly polarized light component parallel to the transmission axis 9a of the front polarizing plate 9 is transmitted through the front polarizing plate 9 and emitted to the observation side.

In the case of transmissive display, light incident from the surface light source and transmitted through the transflective film 16 from the rear side is converted into linearly polarized light by the rear polarizing plate 10, so The polarization state is controlled by refraction, and the light enters the front polarizing plate 9, and light of a linearly polarized light component parallel to the transmission axis 9 a of the front polarizing plate 9 passes through the front polarizing plate 9 and is emitted to the observation side. .

  This liquid crystal display element corresponds to a wavelength band that colors light incident on the observation side of the transflective film 16 from the observation side, reflected from the transflective film 16, and emitted to the observation side. Since the band color compensation filter 17 having the light absorption band is disposed, the reflective display in which the band color is hardly noticeable can be performed.

  That is, in the reflective display, light incident from the observation side is transmitted back and forth through the liquid crystal layer 3 and receives the wavelength dispersion action of the liquid crystal. The liquid crystal display element of this embodiment is incident from the observation side. Since the light reflected by the transflective film 16 and emitted to the observation side is absorbed by the band color compensation filter 17, the band color of the emitted light due to the wavelength dispersion action of the liquid crystal is canceled out. Less reflective display can be performed.

  FIG. 8 shows the peak of the absorptance of the reflective / transmissive liquid crystal display element LCD-3 having the same configuration as that of the above embodiment except the band color compensation filter 17 and the band color compensation filter 17. As the reflection / transmission type liquid crystal display element LCD-4 of the above-described embodiment provided with the filter A having a transmittance of 85% to 90% for light having a wavelength of 540 nm to 560 nm, and the band color compensation filter 17, the peak of the absorptance is obtained. CIE color indicating the chromaticity of each white display of the reflective / transmissive liquid crystal display element LCD-5 of the above-mentioned embodiment provided with the filter B having a transmittance of 80% to 85% for light having a wavelength of 540 nm to 560 nm. FIG.

  As shown in FIG. 8, the chromaticity (x, y coordinate value) of white display on the LCD-3 is x = 0.212, y = 0.342, and the achromatic color point W (x = 0.310, The color difference ΔW with respect to y = 0.316) is as large as ΔW = 0.026.

  On the other hand, the chromaticity of white display of the LCD-4 provided with the filter A having a transmittance of 85% to 90% for the light having a wavelength of 540 nm to 560 nm is x = 0.310 and y = 0.324. The color difference ΔW with respect to the achromatic color point W is as small as ΔW = 0.008.

  Further, the chromaticity of white display of the LCD-5 provided with the filter B in which the transmittance of the light having the wavelength of 540 nm to 560 nm is 80% to 85% is x = 0.309 and y = 0.316. The color difference ΔW with respect to the achromatic color point W is even smaller as ΔW = 0.001.

  As described above, the reflection / transmission type liquid crystal display elements LCD-4 and LCD-5 of the above-described embodiment can obtain a white display with a small color difference ΔW with respect to the achromatic color point W, so that the high-quality reflection in which the band color is hardly noticeable. Display can be made.

In particular, the liquid crystal display element LCD-5 provided with the filter B having the transmittance of light having a wavelength of 540 nm to 560 nm, which is the peak of the absorptivity, as the band color compensation filter 17 has an achromatic point W Since a white display with a smaller color difference ΔW is obtained, a high-quality reflective display without band color can be performed.

  Further, even in transmissive display using illumination light from a surface light source, the band color of the emitted light due to the wavelength dispersion action of the liquid crystal can be canceled by the band color compensation filter 17, and high-quality transmissive display can be performed.

  In the above embodiment, the band color compensation filter 17 is arranged between the rear substrate 2 and the rear side polarizing plate 10. It may be disposed between the film 16 or between the front substrate 1 and the front polarizing plate 9.

(Other embodiments)
The liquid crystal display element of the second embodiment is a reflection / transmission type liquid crystal display element provided with a transflective film 16. However, the present invention relates to the transflective film 16 of the second embodiment. The present invention can also be applied to a reflection type liquid crystal display element having two polarizing plates 9 and 10 having the same configuration as that of the second embodiment except that the reflection film reflects most of the incident light.

Further, the liquid crystal display device of the first and second embodiment, also the liquid crystal molecules 60 ° to 70 ° is a TN-type liquid crystal display device is twisted in the twist angle of 9 0 °, the present invention Other liquid crystal display elements that perform reflective display, for example, STN type liquid crystal display elements in which liquid crystal molecules are twisted with a twist angle of 180 ° or more (eg, 220 ° to 270 °), and the molecular long axes are aligned in one direction. can be applied to horizontally homogeneous alignment type liquid crystal display device of the oriented non-twist was a vertical alignment type liquid crystal molecules were oriented in vertical direction with respect to the substrate surface a liquid crystal display device or the like Te.

1 is a cross-sectional view of a part of a liquid crystal display device showing a first embodiment of the present invention. The orientation processing direction of the pair of substrates in the first embodiment, the direction of the transmission axis of the polarizing plate 9, and the slow axis of the λ / 4 retardation plate and λ / 2 retardation plate constituting the broadband retardation layer The figure which shows direction. FIG. 6 is a spectral characteristic diagram of a band color compensation filter in the first embodiment. FIG. 4 is a CIE chromaticity diagram showing white display chromaticities of a reflective liquid crystal display element that does not include a band color compensation filter and the liquid crystal display element of the first embodiment. Sectional drawing of the part of liquid crystal display element which shows 2nd Example of this invention. The figure which shows the orientation processing direction of a pair of board | substrate in a 2nd Example, and the direction of the transmission axis of a front side polarizing plate and a rear side polarizing plate. FIG. 10 is a spectral characteristic diagram of two types of band color compensation filters in the second embodiment. A reflection / transmission type liquid crystal display element that does not include the band color compensation filter 17, a liquid crystal display element of the second embodiment that includes one of the two types of band color compensation filters, and the two types of band color compensation filters. The CIE chromaticity diagram showing the chromaticity of each white display of the liquid crystal display element of the second embodiment provided with the other.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Front substrate (observation side substrate), 2 ... Rear substrate (substrate opposite to the observation side), 3 ... Liquid crystal layer, 4 ... Pixel electrode, 5 ... TFT, 6 ... Counter electrode, 7, 8 alignment film DESCRIPTION OF SYMBOLS 1a, 2a ... Orientation process direction (alignment direction of a liquid crystal molecule), 9, 10 ... Polarizing plate, 9a, 10a ... Transmission axis, 11 ... Reflecting film, 12 ... Broadband phase difference layer, 13 ... (lambda) / 4 phase difference plate , 13a ... slow axis, 14 ... λ / 2 phase difference plate 14, 14a ... slow axis, 15 ... band color compensation filter, 16 ... transflective film, 17 ... band color compensation filter, 18 ... diffusion layer.

Claims (9)

A liquid crystal layer sealed between a first substrate and a second substrate facing each other ;
A polarizing plate disposed on a surface different from the surface facing the liquid crystal layer of said first substrate provided on the observation side,
A reflective film disposed as a plurality of pixel electrodes on a surface of the second substrate facing the liquid crystal layer, and reflecting light incident from the observation side;
Band color compensation having a light absorption range corresponding to a wavelength range that is disposed on the observation side of the reflection film and that is incident on the observation side and is reflected by the reflection film and colors light emitted to the observation side. Filters,
Equipped with a,
The liquid crystal of the liquid crystal layer is a nematic liquid crystal, and the liquid crystal molecules are twist-oriented at a twist angle of 60 ° to 70 ° between the first substrate and the second substrate,
The band color compensation filter includes a dye filter in which a color dye in a wavelength region corresponding to the light absorption region is dispersed, and has an absorption characteristic having an absorption peak in a wavelength region of 570 nm to 580 nm, and Disposed between the first substrate and the polarizing plate;
The dye filter is a pressure-sensitive adhesive layer in which the dye is dispersed, or a film in which the dye is dispersed in a transparent film.
The liquid crystal display element characterized by the above-mentioned. The band color compensation filter has an absorption characteristic in which the transmittance of light having a wavelength of 570 nm to 580 nm is 75% to 80%, and the transmittance of light having a wavelength of 550 nm or less and 590 nm or more is 90% or more, respectively. The liquid crystal display element according to claim 1 . 3. The liquid crystal display element according to claim 1, wherein a value of a product Δnd of a liquid crystal birefringence Δn and a liquid crystal layer thickness d of the liquid crystal layer is set to 210 nm to 240 nm. The wide-band phase difference layer which gives the phase difference of 1/4 wavelength with respect to the wavelength light of the whole visible light zone between the polarizing plate and the 1st substrate is characterized by the above-mentioned. The liquid crystal display element according to any one of 1 to 3. The broadband retardation layer is formed by laminating a λ / 4 retardation plate and a λ / 2 retardation plate 14 with their slow axes intersecting at a predetermined angle, and the first substrate and the The λ / 4 phase difference plate is disposed between a polarizing plate and the first substrate, and the λ / 2 phase difference plate is disposed to face the polarizing plate. 5. A liquid crystal display element according to 4. The liquid crystal display element according to claim 5, wherein a retardation value of the λ / 4 retardation plate is set to 100 nm to 130 nm. 7. The liquid crystal display element according to claim 5, wherein a retardation value of the λ / 2 retardation plate is set to 260 nm to 280 nm. The liquid crystal display element according to claim 4, wherein the band color compensation filter is disposed between the first substrate and the broadband retardation layer. The liquid crystal display element according to claim 4, wherein the band color compensation filter is disposed between the broadband retardation layer and the polarizing plate.

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