JP2006251143A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate blueness during black display of an OCB liquid crystal display device. <P>SOLUTION: A liquid crystal display device has a liquid crystal cell 11 which has a bend-aligned liquid crystal layer 20 between a counter substrate 13 and an array substrate 12 and also has color filters of red, green, and blue on one of the substrates, a retardation plate 21 arranged on at least one side of the liquid crystal cell, two polarizing plates 23 and 24 arranged across the liquid crystal cell and retardation plate, and a blue and green light absorbing means 40 which is arranged on the path of light passing through the liquid crystal cell, retardation plate, and polarizing plates and absorbs light in the blue and green wavelength range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device using an OCB (Optically Compensated Birefringence) technique capable of realizing a wide viewing angle and a high-speed response.

  Liquid crystal display devices have been applied to various uses by taking advantage of light weight, thinness, and low power consumption.

  Currently, a twisted nematic (TN) type liquid crystal display device widely used in the market is composed of a liquid crystal material having an optically positive refractive index anisotropy arranged approximately 90 ° between substrates, The optical rotation of incident light is adjusted by controlling the twisted arrangement. Although this TN liquid crystal display device can be manufactured relatively easily, its viewing angle is narrow and its response speed is slow, so that it is not particularly suitable for displaying moving images such as TV images.

  On the other hand, an OCB type liquid crystal display device has attracted attention as an improvement in viewing angle and response speed. The OCB type liquid crystal display device is formed by sealing a liquid crystal material capable of bend alignment between substrates, and the response speed is improved by an order of magnitude compared to the TN type liquid crystal display device. Since this is self-compensated, there is an advantage that the viewing angle is wide. When an image is displayed using such an OCB type liquid crystal display device, light is blocked (black display) in a high voltage application state by controlling birefringence and combining with a polarizing plate, for example. It is conceivable to transmit light (display white) in a state.

However, in the black display state, the liquid crystal molecules are aligned along the electric field direction by applying a high voltage (aligned in the normal direction to the substrate), but the liquid crystal molecules near the substrate are in the normal direction due to the interaction with the alignment film. The light is influenced by the phase difference in a predetermined direction. For this reason, when observed from the normal direction of the substrate, the transmittance during black display cannot be sufficiently reduced, leading to a decrease in contrast. Thus, for example, it is known to combine the uniaxial retardation plate to compensate for the retardation of the liquid crystal layer during black display and to sufficiently reduce the transmittance. In addition, as a method for sufficiently compensating for black display or gradation characteristics even when viewed from an oblique direction, for example, as disclosed in Patent Document 1, a hybrid array of optical negative retardation plates is combined. Is also known.
Japanese Patent Laid-Open No. 10-197862

  By the way, a color liquid crystal display device reflects or transmits incident light such as natural light or a backlight having high color rendering properties and displays it through each color filter, and selects light over the entire light wavelength region in the wavelength pass band of each filter. ing.

  Since the TN liquid crystal display device uses optical rotation for display, even if light is internally reflected between the substrates, there is almost no influence on the display. However, in the OCB liquid crystal display device, the retardation received by the incident light passing through the liquid crystal layer and the retardation of the retardation plate are shifted due to the number of internal reflections, thereby causing a problem that the color balance is lost. Furthermore, since the internally reflected reflected light also has wavelength dispersion, the color balance is further disrupted. In particular, the wavelength range shared by the blue filter for the blue color recognized by bluish purple-blue-blue-green is wider than other colors, and the blue filter characteristic has a wide passband. There is a risk of taste.

  An object of the present invention is to provide a liquid crystal display device having a high response speed and an excellent color balance.

  The present invention provides a filter means that absorbs a blue-green light component of light components that pass through a liquid crystal cell, and adjusts the color balance by attenuating unnecessary light leaking from the blue filter.

  In the present invention, when the center wavelength of blue light is set to 450 nm, filter means for absorbing and attenuating blue-green light by dividing the longer wavelength blue light into blue-green light and the shorter wavelength light as blue-violet light. That is, the blue-green light absorber is emitted from the light source and disposed on the light path passing through the liquid crystal cell and the polarizing plate.

According to the present invention, an array substrate and a counter substrate each having an electrode, the electrodes facing each other, a liquid crystal layer sandwiched between the substrates and arranged in a bend, and a red provided on one of the substrates A liquid crystal cell comprising green, blue and blue color filters,
A phase difference plate disposed on at least one of the liquid crystal cells;
Two polarizing plates disposed across the liquid crystal cell and the retardation plate,
A blue-green light absorbing means disposed on a passage of light passing through the liquid crystal cell, the retardation plate and the polarizing plate and absorbing light in a blue-green wavelength region;
To obtain a liquid crystal display device.

Furthermore, the present invention provides an array substrate and a counter substrate each having an electrode, the electrodes facing each other, a liquid crystal layer sandwiched between the substrates and arranged in a bend, and a red provided on one of the substrates A liquid crystal cell comprising green, blue and blue color filters,
A phase difference plate disposed on at least one of the liquid crystal cells;
Two polarizing plates disposed across the liquid crystal cell and the retardation plate,
A light source for supplying light passing through the liquid crystal cell, the retardation plate and the polarizing plate;
A blue-green light absorbing means disposed on the light path from the light source for absorbing light in a blue-green wavelength region;
To obtain a liquid crystal display device.

  Preferably, the light source includes a lamp and a light guide plate that diffuses light generated from the lamp and enters the liquid crystal cell side, and the blue-green light absorbing means is disposed on the liquid crystal cell side of the light guide plate. .

  Alternatively, the blue-green light absorbing means is preferably disposed between the lamp and the light guide plate.

  The blue-green light absorbing means can be easily formed of blue-green absorbing glass or a light interference film.

  The blue-green wavelength region to be absorbed is preferably 450 nm to 470 nm.

  Furthermore, the absorptivity of the blue-green light absorbing means is preferably 30% or more with respect to 450 nm to 470 nm of blue-green light.

  According to the present invention, it is preferable that the blue-green light absorbing means is formed of at least one of the counter substrate and the array substrate.

  Furthermore, it is preferable that at least one of the array substrate and the counter substrate is blue-green light absorbing glass.

Furthermore, the present invention provides an array substrate and a counter substrate each having an electrode, the electrodes facing each other, a liquid crystal layer sandwiched between the substrates and arranged in a bend, and a red provided on one of the substrates A liquid crystal cell comprising green, blue and blue color filters,
A phase difference plate disposed on at least one of the liquid crystal cells;
A polarizing plate disposed on the counter substrate side of the liquid crystal cell;
A reflector disposed on the array substrate side of the liquid crystal cell;
A blue-green light absorbing means for absorbing light in a blue-green wavelength region that is disposed on a path of light that is incident from the counter substrate side of the liquid crystal cell, is reflected by the reflector, and is emitted to the counter substrate side;
A reflective liquid crystal display device is obtained.

  In the present invention, a blue-green light absorber is disposed on the light path passing through the liquid crystal cell, so that transmission of a blue-green light component is suppressed in a blue light region of blue-green-blue-blue-violet light and a wide wavelength range. It is possible to easily control the retardation of blue light, prevent light leakage of blue light, and eliminate the bluishness of an image generated during black display.

  Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of a liquid crystal display device according to the OCB mode system of the present embodiment.

  This liquid crystal display device 1 has an aspect ratio of 16: 9 and a diagonal type of 22. The light transmission type active matrix liquid crystal panel 100 and a plurality of tubular light sources 310 (see FIG. 10) are arranged in parallel. A backlight 300 configured and disposed on the back of the liquid crystal panel, scanning line drive circuits Ydr1 and Ydr2 (see FIG. 3) that are included in the liquid crystal panel 100 and supply the scanning signal Vg to the scanning line Yj, and signal lines Xi (see FIG. 3). 3), a signal line driving circuit 500 configured by a TCP (Tape Carrier Package) for supplying the signal voltage Vsig, a common electrode driving circuit 700 for supplying the counter electrode voltage Vcom to the counter electrode Ecom (see FIG. 2), When the scanning line driving circuits Ydr1, Ydr2, the signal line driving circuit 500, and the common electrode driving circuit 700 are controlled, the control circuit 90 The liquid crystal panel 100 is sandwiched between a backlight 300 and a frame-shaped bezel 1000.

  As shown in FIG. 2, the liquid crystal panel 100 includes a liquid crystal cell 110, a front hybrid retardation plate 200a, a front biaxial retardation plate 210a, a front polarizing plate 220a, a rear hybrid retardation plate 200b, and a rear biaxial retardation plate. 210b and rear polarizing plate 220b. The front hybrid retardation plate 200a, the front biaxial retardation plate 210a, and the front polarizing plate 220a are integrally formed. Similarly, the rear hybrid retardation plate 200b, the rear biaxial retardation plate 210b, and the rear polarizing plate 220b are also formed. The liquid crystal cells 110 are integrally formed and attached to the main surface.

  The liquid crystal cell 110 includes an array substrate 120 having display pixel electrodes, a counter substrate 130 disposed so that a counter electrode faces the display pixel electrodes of the array substrate, and a space between the array substrate 120 and the counter substrate 130. The liquid crystal layer 140 is sandwiched between alignment films 151 and 153.

<Configuration of array substrate>
The array substrate 120 will be described with reference to FIGS.

  In the array substrate 120, a signal line Xi composed of a plurality of aluminum (Al) and a scanning line Yj composed of a plurality of molybdenum-tungsten alloys (MoW) are formed on a transparent glass substrate GLS1 with silicon oxide ( They are arranged in a matrix via an interlayer insulating film INS2 made of (SiO2) film. In addition, an auxiliary capacitance line Cj created in the same process as the scanning line Yj is arranged in parallel with the scanning line Yj.

  In the vicinity of the intersection of the signal line Xi and the scanning line Yj, ITO (Indium Tin Oxide) is used as a transparent electrode through a passivation film INS3 on a top gate thin film transistor TFT having a polycrystalline silicon (p-Si) film as an active layer. The display pixel electrode Dpix is formed. More specifically, this TFT has a double gate structure in order to reduce off-leakage current, and includes P-type source / drain regions p-Si (s), p-Si (d), channel region p-Si (c1). ), P-Si (c2), a connection region p-Si (i) disposed between the channel regions p-Si (c1) and p-Si (c2) in the p-Si film, and a drain region p- Si (d) is connected to the signal line Xi through the contact hole CH1, and the source region p-Si (s) is routed by the source wiring EXT made of Al through the contact hole CH2, and through the contact hole CH3. It is connected to the display pixel electrode Dpix.

  A gate insulating film INS1 made of TEOS is disposed on the p-Si film, a first gate electrode G1 extending from the scanning line Yj is disposed thereon, and a part of the scanning line Yj is a second gate. It is wired as an electrode G2. The first gate electrode G1 corresponds to the first channel region p-Si (c1), and the second gate electrode G2 corresponds to the second channel region p-Si (c2).

  Further, the source region p-Si (s) of this TFT includes a source region extension part p-Si (se) (FIG. 5), and is extended from the auxiliary capacitance line Cj and formed in the same process as the auxiliary capacitance line Cj. The second auxiliary capacitance electrode EC2 disposed on the first auxiliary capacitance electrode EC1 including the interlayer insulating film INS2 is electrically connected via the contact hole CH4. The second auxiliary capacitance electrode EC2 is made of Al formed in the same process as the signal line Xi. Further, a phase change pixel electrode Tpix formed in the same process as the display pixel electrode Dpix is disposed on the second auxiliary capacitance electrode EC2 via the passivation film INS3, and the phase change pixel electrode Tpix is formed in the contact hole CH5. Is electrically connected to the second auxiliary capacitance electrode EC2.

  With such a configuration, the storage capacitor Cs (FIG. 3) is formed between the first storage capacitor electrode EC1 and the second storage capacitor electrode EC2, and the phase change pixel electrode Tpix is disposed on the storage capacitor Cs. Therefore, it is possible to effectively secure a large storage capacity Cs without impairing the aperture ratio.

  Further, in this embodiment, the display pixel electrode Dpix and the phase transition pixel electrode Tpix are arranged across the scanning line Yj, and the source region extension portion p− independent from the source region p-Si (s) of the TFT. Since it is connected by Si (se), even if there is a short circuit or the like in the storage capacitor Cs, the source region extension portion p-Si (se) can be easily separated by means such as laser irradiation. Can be rescued.

  Further, the display pixel electrode Dpix and the phase transition pixel electrode Tpix in the next horizontal line adjacent on the storage capacitor line Cj are configured in a comb-teeth shape in which the opposite end sides mesh with each other. By applying a twisted lateral electric field between the display pixel electrode Dpix and the phase transition pixel electrode Tpix, it becomes possible to uniformly nucleate the bend, which is uniform from the initial spray arrangement state. It is possible to lead to a bend arrangement state. This comb tooth pitch is, for example, smaller than 50 μm, and desirably smaller than 20 to 30 μm, thereby making it possible to lead to a uniform arrangement at a low voltage.

  Incidentally, as shown in FIG. 3, both ends of the scanning line Yj are electrically connected to scanning line driving circuits Ydr1 and Ydr2 integrally formed on the glass substrate GLS1, respectively. The vertical scanning clock signal YCK and the vertical start signal YST are input to the scanning line driving circuits Ydr1 and Ydr2, respectively. The auxiliary capacitance line Cj is connected to the connection wiring Ccs at both ends, and the auxiliary capacitance voltage Vcs is input through the connection wiring Ccs. The signal line Xi is connected to the signal input line xk (k = i / 2) via the selection switch SEL. Specifically, the signal line Xi is divided into an odd signal line Xi (i = 1, 3, 5,...) And an even signal line Xi (i = 2, 4, 6,. A pair of odd signal lines Xi, Xi + 2 are connected to the same signal input line xk via selection switches SEL1, SEL3, and a pair of adjacent even signal lines Xi + 1, Xi + 3 are input to the same signal via selection switches SEL2, SEL4. Connected to line xk + 1. The selection switch SEL1 connected to one of the odd signal line pairs and the selection switch SEL4 connected to one of the even signal line pairs are selected by the first selection signal Vsel1 and connected to the other of the odd signal line pairs. The selection switch SEL3 and the selection switch SEL2 connected to the other of the even signal line pair are wired so as to be selected by the second selection signal Vsel2.

  For example, as shown in FIG. 7A, the signal voltage Vsig1 having a positive polarity (+) with respect to the counter electrode voltage Vcom is applied to the display pixel electrode Dpix corresponding to the signal line X1 in the first half of one horizontal scanning period (1H). The negative (−) signal voltage Vsig4 with respect to the counter electrode voltage Vcom is written to the display pixel electrode Dpix corresponding to the signal line X4. Then, in the latter half of one horizontal scanning period (1H), the display pixel electrode Dpix corresponding to the signal line X2 has a negative (−) signal voltage Vsig2 with respect to the counter electrode voltage Vcom, and the display pixel electrode corresponding to the signal line X3. A signal voltage Vsig3 having a positive polarity (+) with respect to the counter electrode voltage Vcom is written to Dpix. Further, as shown in FIG. 7B, a negative (−) signal with respect to the counter electrode voltage Vcom is applied to the display pixel electrode Dpix corresponding to the signal line X1 in the first half of one horizontal scanning period (1H) of the next frame. The voltage Vsig1 is written to the display pixel electrode Dpix corresponding to the signal line X4 as a signal voltage Vsig4 having a positive polarity (+) with respect to the counter electrode voltage Vcom. In the second half of one horizontal scanning period (1H), the display pixel electrode Dpix corresponding to the signal line X2 has a positive (+) signal voltage Vsig2 with respect to the counter electrode voltage Vcom, and the display pixel electrode corresponding to the signal line X3. A signal voltage Vsig3 having a negative polarity (−) with respect to the counter electrode voltage Vcom is written to Dpix.

  In this way, frame inversion driving and dot inversion driving are performed, thereby preventing the application of an undesired DC voltage and effectively preventing the occurrence of flicker. Further, since the number of connections between the signal line driving circuit 500 and the liquid crystal panel 100 is reduced to i / 2 with respect to the number i of the signal lines Xi, the connection process is greatly reduced and the number of connection points is small. As a result, improvement in manufacturing yield, improvement in impact resistance, and the like are achieved. Moreover, the connection pitch limit accompanying high definition can be expanded, and for example, high definition of 80 μm or less can be achieved.

  In the above embodiment, the signal voltage Vsig input from a certain signal input line xk is serially distributed to every other two signal lines Xi and Xi + 2 within one horizontal scanning period (1H). It is also possible to distribute to three signal lines or four signal lines, and in this way, the number of connections can be further reduced. However, since increasing the number of distributions shortens each writing time, it is necessary to design appropriately according to the capability of the TFT.

<Configuration of counter substrate>
The counter substrate 130 is a matrix-shaped light-shielding film BM that blocks undesired leakage light on the glass substrate GLS2, and red R, green G, and blue B provided corresponding to each display pixel electrode Dpix for color display. Each color filter CF (R), CF (G), CF (B) and transparent counter electrode Ecom made of ITO is provided. Although not shown here, CF (G) and CF (B) are sequentially adjacent to CF (R).

  Although not shown, resinous column spacers are arranged on the counter electrode Ecom, and are regularly arranged at a ratio of one to a plurality of pixels so as to maintain a gap with the array substrate 110. . The position corresponding to the space on the array substrate is a wide area Xa on the signal line shown in FIG.

<Configuration of LCD panel>
Next, the configuration of the liquid crystal panel 100 will be described in more detail.

  As shown in FIG. 2, the alignment films 151 and 153 arranged on the main surfaces of the arrays and the counter substrates 120 and 130 have the rubbing directions Ra and Rb (see FIGS. 8 and 9) on the substrates 120 and 130, respectively. The rubbing process is performed in the vertical direction so as to be substantially parallel to and in the same direction. The pretilt angle (θ) is set to approximately 10 °. A liquid crystal layer 140 is sandwiched between the two substrates 120 and 130. For the liquid crystal layer 140, a p-type nematic liquid crystal having a positive dielectric anisotropy in which the liquid crystal molecules bend in the state where a predetermined voltage is applied to the display pixel electrode Dpix and the counter electrode Ecom is used.

  By the way, as shown in FIG. 9A, the liquid crystal molecules 140a of the liquid crystal layer 140 are in a splay alignment state when no voltage is applied between the display pixel electrode Dpix and the counter electrode Ecom. For this reason, when the power is turned on, a high voltage of about several tens V is applied between the display pixel electrode Dpix and the counter electrode Ecom to shift to the bend arrangement state. In order to surely perform this phase transition, when a high voltage is applied, a voltage having a reverse polarity is sequentially written for each adjacent horizontal pixel line, so that a horizontal direction is provided between the adjacent display pixel electrode Dpix and the phase transition pixel electrode Tpix. Nucleation is performed by giving a torsional potential difference of, and phase transition is performed around this nucleus. By performing such an operation for about 1 second, the splay arrangement state is shifted to the bend arrangement state, and the potential difference between the display pixel electrode Dpix and the counter electrode Ecom is set to the same potential, thereby causing an undesired history once. to erase.

  After making the bend alignment state in this way, during operation, a voltage equal to or higher than the low off voltage Voff at which the bend alignment state is maintained is applied to the liquid crystal molecules 140a as shown in FIG. 9B. By changing the voltage between this off-voltage and the higher on-voltage Von, the alignment state is changed between (b) to (c) in the figure, and the retardation value of the liquid crystal layer 140 is changed to λ / 2 to change the transmittance.

  In order to achieve such an operation, as shown in FIG. 8, the absorption axes Aa and Ab of the pair of polarizing plates 220a and 220b are orthogonal to each other so as to display black when the on voltage Von is applied, and the rubbing direction Ra, The arrangement is shifted from Rb by π / 4.

  Further, the front hybrid phase difference plate 200a and the rear hybrid phase difference plate 200b attached between the outer surfaces of the array substrate 120 and the counter substrate 130 and the polarizing plates 220a and 220b are liquid crystal at the time of on-voltage (black display). It compensates for the retardation value RLCon of the layer 140, for example, 80 nm, and further prevents unwanted light leakage from the front and oblique directions during black display. That is, the discotic liquid crystal constituting the hybrid phase difference plates 200a and 200b is an optical negative material in which the refractive indexes nx and ny are equal and the refractive index nz in the optical axis direction is smaller than nx and ny. 2 and 8, the molecular optical axis Dopt is inclined in the opposite direction to the optical axis inclination direction of the liquid crystal molecules 140a of the liquid crystal layer 140, and the inclination angle is gradually changed in the film thickness direction. Each of the retardation values RD is -40 nm. Accordingly, since the retardation RLCon of the liquid crystal layer 140 at the time of black display is 80 nm, the phase difference at the time of black display is canceled, thereby preventing unwanted light leakage.

  Further, biaxial retardation plates 210a and 210b are disposed between the hybrid retardation plates 200a and 200b and the polarizing plates 220a and 220b, respectively. The biaxial retardation plates 210a and 210b prevent light leakage due to the optical rotation of the liquid crystal layer 140 in an oblique direction. The biaxial retardation plates 210a and 210b are respectively connected to the absorption axes Aa and Ab of the polarizing plates 220a and 220b. Are matched. Therefore, the phase difference from the front direction can be made substantially zero by the combination with the polarizing plates 220a and 220b, and only the chromatic dispersion in the oblique direction can be selectively improved.

<Backlight configuration>
The backlight 300 disposed facing the back polarizing plate 220b will be described with reference to FIG.

  The backlight 300 includes, for example, a plurality of tubular light sources 310 arranged side by side as shown in FIG. 5A, and a resin that efficiently emits light from the tubular light sources 310 to the front surface and accommodates the tubular light sources 310. A reflector 320 made of light, an optical sheet disposed between the polarizing plate 220b (see FIG. 2) and the tubular light source 310, and a blue-green light absorber 330 disposed between the optical sheet and the tubular light source 310. It is prepared for.

  The optical sheet is a prism such as 3M BEFIII in which a diffusion plate 340 made by Tsujiden Co., for example, to ensure luminance uniformity, and a plurality of prism rows that collect light source light emitted from the tubular light source 310 are arranged. It is composed of sheets 350 and 360.

The tubular light source 310 is composed of a high color rendering lamp typified by a three-wavelength cold cathode fluorescent tube. As an example, the tubular light source 310 has an emission spectrum as shown by a curve A in FIG. 11 and has a peak at 610 nm. The region has a green light region having a peak at 540 nm and a blue light region having a peak at 435 nm. As a light emitting phosphor excited by 147 nm ultraviolet rays when xenon gas is used as a discharge gas of a lamp, Y ₂ O ₃ : Eu phosphor for red, LaPO ₄ : Ce, Tb phosphor for green, and blue Although a BAM phosphor is used, other phosphors are often used, and there is no great difference in the emission spectrum for obtaining high color rendering properties.

  Each of the color filters CF (R), CF (G), and CF (B) has transmission characteristics that share these light wavelengths, the red filter CF (R) is 580 nm or more, and the green filter CF (G) is 580 to The 510 nm blue filter CF (B) has a pass characteristic of 550 to 400 nm. The pass band of the blue filter CF (B) is wide, that is, the pass region of the blue filter CF (B) includes a sharp peak at 435 nm, a low wide peak at 450 nm, and a low sharp peak at 490 nm in the emission spectrum of the lamp. , It can be divided into a blue-violet region (including blue) and a blue-green region with a wavelength of 450 nm as a boundary.

The blue-green light absorber 330 absorbs at least a part of the blue-green spectral region. As shown by a curve B in FIG. 11, the absorption characteristic shows an absorption rate of 30% or more at a wavelength of 450 to 470 nm, and an undesired light leakage can be prevented as the absorption rate is higher. A curve C is the characteristic color of the liquid crystal panel 100 filter has red _{C R,} green _{C G,} the filter characteristics of blue _{C B.}

  As shown in FIG. 12, the spectral radiance at the time of black display shows the characteristics when the absorber is formed of a blue-green light absorbing glass plate, and it can be seen that when there is an absorbing glass, it is significantly reduced in this region. . Here, D shows the characteristics when there is an absorbing glass, and A shows the characteristics when there is no absorbing glass.

  10A has a structure in which a blue-green light absorber 330 is disposed on a tubular light source 310, and the blue-green light absorber 330 has a thickness including, for example, holmium (element symbol: Ho) as a composition component. A glass plate having an absorption characteristic of about 2.5 μm and indicated by curve B in FIG. 11 was used.

  FIG. 6B shows a modification of the present embodiment, in which a side light type surface light source is used as a backlight, and a light guide plate 370 made of acrylic resin or the like, and a tubular tube disposed on the side surface of the light guide plate 370. A light source 310, a reflector 380 that efficiently guides the light source light from the tubular light source 310 to the light guide plate 370, a blue-green light absorber 330 disposed on the exit surface of the light guide plate 310, a diffuser plate 340 disposed thereon, and It is composed of prism sheets 350 and 360 disposed thereon. Even with such a configuration, the same effects as described above can be achieved.

  FIG. 10C is another modification of the present embodiment. The arrangement position of the blue-green light absorber 330 is changed between the tubular light source 310 and the light guide plate 370. A similar configuration is required. By adopting such a configuration, there is an advantage that it can be formed in a smaller size as compared with the above-described embodiments and modifications.

  Moreover, it can replace with said Example and modification, and the lamp envelope itself which comprises the tubular light source 310 can also be formed with a blue-green light absorption glass.

<Display operation>
With the above configuration, the light emitted from the tubular light source 310 passes through the polarizer 220b through the absorber 330 on the light path L as shown in FIG. Here, only the polarized light that has passed through the transmission axis orthogonal to the absorption axes Aa and Ab of the polarizing plate 220b is emitted and is incident on the liquid crystal cell 110 through the rear biaxial retardation plate 210b and the rear hybrid retardation plate 200b. .

  Since the total retardation of the liquid crystal layer 140 and all the retardation plates at the on voltage in the normal direction is substantially zero, the polarized light passes through as it is and reaches the polarizing plate 220a on the front side. Since the polarizing plates 220a and 220b have a crossed Nicols arrangement, the polarized light is absorbed and blocked by the front polarizing plate 220a to obtain a black display.

  Since the retardation of the liquid crystal layer 140 changes according to the voltage application state between the on-voltage and the off-voltage, and the difference from the retardation of all the retardation plates changes, the incident light emitted from the front biaxial retardation plate 210a is elliptically polarized. Thus, the light reaches the front polarizing plate 220a, and light is transmitted corresponding to the polarization state. By varying the applied voltage in this way, gradation display is possible.

  When attention is paid to blue light, the wavelength component of 450 to 470 nm is sufficiently attenuated by the blue-green light absorber 330 in the light emitted from the tubular light source 310, so that the retardation for blue light is 450 nm or less, for example, 440 nm. Can be adjusted to zero. Therefore, the phase difference increases as the wavelength moves away from 440 nm. Even if the control for long wavelength light is not sufficient, and the pass band of the blue filter CF (B) is wide and the blocking region is shifted, the blue- By controlling the light in the blue-violet spectral region, it becomes possible to prevent light leakage of blue light.

  Furthermore, even if the retardation between the liquid crystal layer 140 and the entire retardation plate is shifted due to undesired reflection in the liquid crystal cell 110, the light emitted from the tubular light source 310 is 450 to 450 by the blue-green light absorber 330. Since the wavelength component of 470 nm is sufficiently attenuated, coloring of transmitted light can be reduced.

  In each of the above embodiments, the absorber 330 is disposed between the tubular light source 310 and the optical film. However, the absorber 330 may be disposed between the liquid crystal panel 110 and the optical film.

(Embodiment 2)
FIG. 13 shows the liquid crystal cell 110 of the present embodiment, which is different from the above-described embodiment in that the glass substrate GSL2 constituting the counter substrate 130 is formed of blue-green absorbing glass instead of the arrangement of the absorber 330. Have the same configuration. By adopting such a configuration, it is possible to prevent light leakage of blue-green light that finally passes through the liquid crystal cell 110, and it is possible to prevent bluishness from occurring in black display.

  In addition, for example, as shown in FIG. 14, the glass substrate GSL1 constituting the array substrate 120 can be formed of blue-green light absorbing glass. Thereby, the blue-green light component of the light incident on the liquid crystal cell 110 from the backlight 300 can be filtered to prevent the same component from entering the liquid crystal layer 140, and the same effect as that of the first embodiment can be obtained. be able to.

  Further, blue-green light absorbing glass can be used for each of the glass substrates GSL1 and GSL2 constituting the array and the counter substrates 120 and 130.

  The second embodiment is also useful when natural light having all visible light wavelength components is used as transmitted light.

Further, as shown in FIG. 15, the glass substrates GSL1 and GSL2 themselves may be transparent glass instead of the blue-green light absorbing glass, and for example, the light interference film 150 may be formed on the outer surface of the array substrate 120. This film has an advantage that an absorption characteristic of an arbitrary wavelength can be easily obtained and an abrupt absorption characteristic can be obtained due to an alternate laminated structure of layers of a high refractive index material and a low refractive index material. In the present embodiment, a sufficient effect can be obtained by stacking three layers of SiO ₂ layers and Al ₂ O ₃ layers with a quarter wavelength thickness.

(Embodiment 3)
This embodiment shows an OCB mode reflective liquid crystal display device. 8 denote the same parts, and a description thereof will be omitted. In consideration of the retardation of the liquid crystal cell 110 being a reflection type, the birefringence anisotropy or the cell gap of the liquid crystal material is adjusted to be ½ that of the above embodiment.

  In the reflection type liquid crystal display device 2, as a polarizing plate, one polarizing plate 220 a may be arranged on the front side, while a reflecting plate 160 is arranged on the back side of the liquid crystal cell 110. Natural light incident on the polarizing plate 220a becomes linearly polarized light having a component of the transmission axis Ta of the polarizing plate 220a, passes through the biaxial retardation plate 210a, the front hybrid retardation plate 200a, and the liquid crystal cell 110, and is reflected by the reflection plate 160. The phase is inverted and shifted by 90 ° to return to the return path and reach the polarizing plate 220a again. In the meantime, when the phase difference is not received by each element, the linearly polarized light is absorbed by the polarizing plate 220a and becomes black display. If the retardation of the liquid crystal cell 110 is changed to make elliptically polarized light due to the influence of the phase difference, a part of the return light is transmitted through the polarizing plate 220a and gradation display is possible. Since light passes through each element twice, as described above, it is necessary to adjust the thickness, retardation and the like accordingly.

  By the way, since the glass substrate GSL2 of the counter substrate 130 constituting the liquid crystal cell 110 is made of blue-green light absorbing glass, the blue-green light component of the natural light passing through the liquid crystal cell 110 twice is absorbed. Pixel retardation control can be performed in a narrow region of blue light, light leakage can be easily prevented, and the occurrence of a bluish image during black display due to blue leakage can be prevented.

1 is a schematic configuration diagram of a liquid crystal display device according to an embodiment of the present invention. Partially enlarged schematic sectional view of a liquid crystal cell of one embodiment Schematic equivalent circuit diagram of the liquid crystal cell of one embodiment The partial schematic front view of the array substrate of one Embodiment The partial schematic front view of the array substrate of one Embodiment (A) is a partial schematic sectional view of the array substrate cut along the BB line in FIG. 5, (b) is a partial schematic sectional view of the array substrate cut along the CC line. The figure for demonstrating the display state of one Embodiment Schematic configuration diagram of a liquid crystal cell of one embodiment (A), (b), (c) is the schematic explaining operation | movement of one Embodiment. (A), (b), (c) is schematic sectional drawing of the backlight of Embodiment 1. FIG. Curve diagram showing spectral radiance characteristics of backlight lamp, absorption characteristics of blue-green light absorber and transmission characteristics of red, green and blue filters Curve diagram showing spectral radiance characteristics during black display Schematic sectional view showing the structure of a liquid crystal cell according to Embodiment 2 of the present invention. Schematic cross-sectional view showing a modification of the liquid crystal cell of Embodiment 2. Schematic sectional view showing another modification of the liquid crystal cell of Embodiment 2. Schematic configuration diagram of a liquid crystal cell of another embodiment

Explanation of symbols

110: Liquid crystal cell 120: Array substrate 130: Counter substrate CF (R), CF (G), CF (B): Color filter 140: Liquid crystal layer 200a, 200b: Hybrid retardation plate 210a, 210b: Biaxial retardation plate 220a, 220b: Polarizing plate 300: Backlight 330: Blue-green light absorber

Claims (11)

An array substrate having electrodes and an electrode substrate facing each other, a liquid crystal layer sandwiched between the substrates and arranged in a bend, and red, green, and blue color filters provided on one of the substrates A liquid crystal cell consisting of
A phase difference plate disposed on at least one of the liquid crystal cells;
Two polarizing plates disposed across the liquid crystal cell and the retardation plate,
A blue-green light absorbing means disposed on a passage of light passing through the liquid crystal cell, the retardation plate and the polarizing plate and absorbing light in a blue-green wavelength region;
A liquid crystal display device comprising: An array substrate and an opposing substrate each having an electrode, the electrodes facing each other, a liquid crystal layer sandwiched between the substrates and arranged in a bend, and red, green, and blue colors provided on one of the substrates A liquid crystal cell comprising a filter;
A phase difference plate disposed on at least one of the liquid crystal cells;
Two polarizing plates disposed across the liquid crystal cell and the retardation plate,
A light source for supplying light passing through the liquid crystal cell, the retardation plate and the polarizing plate;
A blue-green light absorbing means disposed on the light path from the light source for absorbing light in a blue-green wavelength region;
A liquid crystal display device comprising: The light source includes a lamp and a light guide plate that diffuses light generated from the lamp and enters the liquid crystal cell, and the blue-green light absorbing means is disposed on the liquid crystal cell side of the light guide plate. The liquid crystal display device according to claim 2. The light source includes a lamp and a light guide plate that diffuses light generated from the lamp and enters the liquid crystal cell side, and the blue-green light absorbing means is disposed between the lamp and the light guide plate. The liquid crystal display device according to claim 2. 3. A liquid crystal display device according to claim 1, wherein the blue-green light absorbing means is made of blue-green absorbing glass. 3. The liquid crystal display device according to claim 1, wherein the blue-green light absorbing means is a light interference film. The liquid crystal display device according to claim 1, wherein the blue-green wavelength region to be absorbed is 450 nm to 470 nm. The liquid crystal display device according to any one of claims 1 to 7, wherein the blue-green light absorbing means has an absorptance of 450 nm to 470 nm in a blue-green wavelength region of 30% or more. 2. The liquid crystal display device according to claim 1, wherein the blue-green light absorbing means is formed on at least one of the array substrate and the counter substrate. The liquid crystal display device according to claim 9, wherein at least one of the array substrate and the counter substrate is blue-green light absorbing glass. An array substrate and an opposing substrate each having an electrode, the electrodes facing each other, a liquid crystal layer sandwiched between the substrates and arranged in a bend, and red, green, and blue colors provided on one of the substrates A liquid crystal cell comprising a filter;
A phase difference plate disposed on at least one of the liquid crystal cells;
A polarizing plate disposed on the counter substrate side of the liquid crystal cell;
A reflector disposed on the array substrate side of the liquid crystal cell;
A blue-green light absorbing means for absorbing light in a blue-green wavelength region that is disposed on a path of light that is incident from the counter substrate side of the liquid crystal cell, is reflected by the reflector, and is emitted to the counter substrate side;
A reflective liquid crystal display device.

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