JP2011197590A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve contrast in a liquid crystal display device having a liquid crystal layer including a medium showing a blue phase.SOLUTION: The liquid crystal display device comprises a first substrate SUB1 and a second substrate SUB2, a first liquid crystal layer BP1 with a blue phase liquid crystal sealed therein disposed between the first substrate SUB1 and the second substrate SUB2, a second liquid crystal layer BP2 disposed to the second substrate SUB2 side with respect to the first liquid crystal layer BP1 between the first substrate SUB1 and the second substrate SUB2, and an electrode group PX for applying an electric field having an in-plane direction component of the first substrate SUB1 to the first liquid crystal layer BP1. The second liquid crystal layer BP2 shows an optical rotatory power opposite to that of the first liquid crystal layer BP1.

Description

  The present invention relates to a liquid crystal display device.

  A polymer-stabilized blue phase liquid crystal sandwiched between a pair of transparent substrates as a liquid crystal display element that eliminates the need for surface alignment processing, significantly improves the response speed of moving image display, and does not leak light (provides a dark field) during black display. There is a liquid crystal display element comprising: A liquid crystal display element using a polymer-stabilized blue phase liquid crystal exhibits a large change in birefringence when an electric field is applied in the in-plane direction to the cell substrate. The polymer-stabilized blue phase liquid crystal is composed of a low molecular liquid crystal capable of developing a blue phase between a chiral nematic phase and an isotropic phase, and a polymer network formed in the low molecular liquid crystal. Further, Patent Document 1 proposes a liquid crystal display element that does not leak light (provides a dark field) during black display by optimizing the type and amount of Kaleyl dopant added to the liquid crystal.

  In addition, liquid crystal materials for optical elements that can be driven at low voltage, have a large phase difference, and develop a blue phase over a temperature range that can be practically used, and also have high light transmittance and long-term stable operation. Patent document 2 is mentioned as a liquid crystal material for optical elements. As a solution, a liquid crystal / polymer composite obtained by polymerizing a liquid crystal composition comprising a liquid crystal compound, a chiral agent, a monofunctional polymerizable monomer, and a polyfunctional polymerizable monomer, The combination of the liquid crystal compound and the chiral agent has a dielectric anisotropy (Δε) of 30 or more and a refractive index anisotropy (Δn) of 0.13 or more. Patent Document 2 proposes an improvement in light extraction efficiency by a liquid crystal material for an optical element having a blue phase in combination with an agent and a light modulation element using the same.

International Publication WO2005 / 090520 International Publication WO2005 / 080529

  In a conventional liquid crystal display element having a liquid crystal layer that exhibits a blue phase, it has been difficult to obtain a desired contrast. An object of the present invention is to improve the contrast of a liquid crystal display device having a liquid crystal layer in which blue phase liquid crystal is sealed.

  In order to solve the above problems, a liquid crystal display device according to the present invention includes a first substrate and a second substrate, and a first substrate disposed on an opposite side of the first substrate with respect to the second substrate. A polarizing plate, a second polarizing plate disposed on the opposite side of the second substrate with respect to the first substrate, and disposed between the first substrate and the second substrate; A first liquid crystal layer in which a phase liquid crystal is sealed, and a second liquid crystal disposed between the first substrate and the second substrate on the second substrate side with respect to the first liquid crystal layer And an electrode group that applies an electric field having an in-plane direction component of the first substrate to the first liquid crystal layer, and the second liquid crystal layer is represented by the first liquid crystal layer. It is characterized by exhibiting optical rotation in the opposite direction to optical rotation.

  In the liquid crystal display device according to one aspect of the present invention, the first liquid crystal layer may have a Bragg diffraction wavelength of 380 nm or less.

  In one mode of the liquid crystal display device according to the present invention, a blue phase liquid crystal may be sealed in the second liquid crystal layer.

  In one mode of the liquid crystal display device according to the present invention, the second liquid crystal layer may be filled with a liquid crystal exhibiting a chiral nematic phase.

  In the liquid crystal display device according to one aspect of the present invention, the liquid crystal display device further includes a third substrate between the first substrate and the second substrate, and the first liquid crystal layer includes The second liquid crystal layer may be disposed between the first substrate and the third substrate, and the second liquid crystal layer may be disposed between the second substrate and the third substrate. .

  In one embodiment of the liquid crystal display device according to the present invention, the first liquid crystal layer and the second liquid crystal layer may be arranged to have an interface in contact with each other.

  In the liquid crystal display device according to one aspect of the present invention, the first liquid crystal layer and the second liquid crystal layer may be separated from each other by a separation film.

  In one embodiment of the liquid crystal display device according to the present invention, the second liquid crystal layer includes a first liquid crystal material and a second liquid crystal material that exhibit a blue phase and exhibit different Bragg diffraction wavelengths in the visible wavelength region. The first liquid crystal material and the second liquid crystal material may be separately divided in a direction parallel to the second substrate.

  In the liquid crystal display device according to one aspect of the present invention, the electrode group includes a first electrode and a second electrode, and at least the first electrode is an electrode formed in a comb shape. In addition, an electric field having an in-plane direction component of the first substrate may be applied to the first liquid crystal layer by the first electrode and the second electrode.

  In one embodiment of the liquid crystal display device according to the present invention, the liquid crystal display device includes a backlight disposed on the opposite side of the first substrate with respect to the first liquid crystal layer, and the second substrate. And a color filter disposed on the opposite side of the second liquid crystal layer.

  According to the present invention, the contrast can be improved. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a figure which shows schematic structure of the liquid crystal display device concerning 1st Embodiment. It is a figure which shows the pixel circuit of the liquid crystal display panel in 1st Embodiment. It is a figure which shows a mode that the liquid crystal display panel in 1st Embodiment was seen from the upper surface. It is a figure which shows typically the cross section of the liquid crystal display panel in 1st Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel which made the liquid crystal layer 1 layer. It is a figure which shows typically the cross section of the liquid crystal display panel in 2nd Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel in 3rd Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel in 4th Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel in 6th Embodiment. It is a figure explaining the mode of the blue phase liquid crystal stabilized with the polymer chain. It is a figure which shows typically the cross section of the liquid crystal display panel in 7th Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel in 8th Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel in 9th Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel in 10th Embodiment. It is a figure which shows typically the cross section of the liquid crystal display panel in 11th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted.

[First Embodiment]
FIG. 1 is a diagram illustrating a schematic configuration of a liquid crystal display device 1 according to the first embodiment. As shown in the figure, the liquid crystal display device 1 of this embodiment includes a liquid crystal display panel 11, a video signal line driving circuit 12, a scanning line driving circuit 13, a control circuit 14, a backlight 15, and a video signal. A plurality of video signal lines DL connected to the line driving circuit 12 and a plurality of scanning signal lines GL connected to the scanning line driving circuit 13 are configured. Then, as shown in FIG. 2, the drive circuit is connected via the scanning signal line GL and the video signal line DL so that the AC drive voltage ACV is applied to the electrodes CT and PX, and the backlight 15 and the like are further connected. As a result, a liquid crystal display device having the liquid crystal display panel 11 as shown in FIG. 3 is obtained.

  The liquid crystal display panel 11 has a display area DA for displaying an image, and a plurality of pixels are arranged in a matrix in the display area DA. Each of the pixels arranged in the display area DA corresponds to each of the areas defined by the plurality of video signal lines DL and the plurality of scanning signal lines GL.

  FIG. 2 is a diagram for explaining pixels, and is a diagram showing a pixel circuit of the liquid crystal display panel 11 in the present embodiment. As shown in the figure, a thin film transistor (hereinafter referred to as TFT) having a MIS (Metal-Insulator-Semiconductor) structure is formed at the corner of the pixel region defined by the scanning signal line GL and the video signal line DL. The gate electrode of the TFT is connected to the scanning signal line GL, and the drain electrode of the TFT is connected to the video signal line DL. Each pixel has a pixel electrode PX (first electrode) and a common electrode CT (second electrode) corresponding to the pixel electrode PX. The pixel electrode PX is connected to the source electrode of the TFT, and the common electrode CT. Are connected to a common signal line CL.

  In the above circuit configuration, the reference voltage is applied to the common electrode CT of each pixel through the common signal line CL, and the scanning line driving circuit 13 applies the gate voltage through the scanning signal line GL, so that the pixel row is formed. Selected. At the selection timing, the video signal line driving circuit 12 supplies the video signal to each video signal line DL, so that the voltage of the video signal is applied to the pixel electrode PX of each pixel. As a result, a horizontal electric field having an intensity corresponding to the voltage of the video signal is generated between the pixel electrode PX and the common electrode CT in the first liquid crystal layer BP1, and the optical characteristics are controlled by changing the electric field intensity. Is done.

  FIG. 3 is a diagram illustrating a state in which the liquid crystal display panel 11 according to the present embodiment is viewed from the upper surface. The liquid crystal display panel 11 includes a first substrate SUB1 and a second substrate SUB2, and further includes two liquid crystal layers between these substrates. This will be described in detail below.

  FIG. 4 is a diagram schematically showing a cross section of the liquid crystal display panel 11 in the present embodiment. As shown in the figure, the liquid crystal display panel 11 further includes a third substrate SUB3 between the first substrate SUB1 and the second substrate SUB2. A first liquid crystal layer BP1 is disposed between the first substrate SUB1 and the third substrate SUB3, and blue phase liquid crystal is sealed in the first liquid crystal layer BP1. A second liquid crystal layer BP2 exists between the second substrate SUB2 and the third substrate SUB3. In the present embodiment, the second liquid crystal layer BP2 is also a blue phase liquid crystal. In addition, a TFT, a comb-like pixel electrode PX, and a comb-like common electrode CT are formed on the first substrate SUB1, and the electric field strength applied to the first liquid crystal layer BP1 is controlled. The first liquid crystal layer BP1 is filled with blue phase liquid crystal, and an electric field is applied for display control of the pixels. Therefore, in the liquid crystal display device 1 according to the present embodiment, the response speed of moving image display is improved as compared with the liquid crystal display device used for pixel display control by the liquid crystal layer including the nematic liquid crystal.

  Further, the liquid crystal display panel 11 has a polarizing plate PL1 (first polarizing plate) outside the first substrate SUB1 (opposite side of the first liquid crystal layer BP1), and outside the second substrate SUB2 (first one). The polarizing plate PL2 (second polarizing plate) is provided on the opposite side of the second liquid crystal layer BP2. The polarizing plates PL1 and PL2 (SEG1224DU manufactured by Nitto Denko Corporation) in the present embodiment are arranged in crossed Nicols so that their polarization transmission axes are orthogonal to each other. Further, the transmission axes of the polarizing plates PL1 and PL2 are arranged so as to form 45 degrees with respect to the in-plane direction angle of the electric lines of force EFL generated between the pixel electrode PX and the common electrode CT. In a state where no voltage is applied to the first liquid crystal layer BP1, light that has been transmitted from the backlight 15 through the polarizing plate PL1 to become linearly polarized light is blocked by the absorption axis of the polarizing plate PL2 and displayed in black.

  Here, the blue phase liquid crystal in the present specification has a crystal structure exhibiting Bragg diffraction in the visible or ultraviolet region, and appears between a chiral nematic phase having a relatively short helical pitch and an isotropic phase. Layer of liquid crystal. A blue phase liquid crystal is generally known to exhibit optical isotropy. For example, when a blue phase liquid crystal is sealed between two substrates, an electric field is not applied. Optical rotation may be expressed. And this optical rotation is considered to originate in the twist direction of the chiral agent used when producing a blue phase liquid crystal.

  For this reason, the liquid crystal display panel 11 has a second liquid crystal layer BP2 exhibiting optical rotation in the opposite direction to the optical rotation exhibited by the first liquid crystal layer BP1. The second liquid crystal layer BP2 is filled with blue phase liquid crystal and exhibits optical rotation that is in the opposite direction to the optical rotation exhibited by the first liquid crystal layer BP1. Thereby, the influence of the optical rotation that is manifested in the first liquid crystal layer BP1 can be reduced. In the case of only the first liquid crystal layer BP1, the luminance of black display increases due to the optical rotation, but the second liquid crystal layer BP2 exhibiting optical rotation in the opposite direction to the first liquid crystal layer BP1 is provided. By being present, the influence of optical rotation can be reduced, and the brightness of black display can be reduced to improve the contrast.

  In the following, the preparation of the blue phase liquid crystal contained in the first liquid crystal layer BP1 and the second liquid crystal layer BP2 will be described. In the present embodiment, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are filled with a blue phase liquid crystal stabilized by a polymer chain, and the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are sealed. Both show a blue phase. In a state where no electric field is applied to the first liquid crystal layer BP1 (black display state), the optical rotations exhibited by the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are opposite to each other. As shown.

混合液晶中の組成比（ＪＣ１０４１−ＸＸ／５ＣＢ／ビナフチル誘導体）は、４８／４８／４（ｍｏｌ％）とした。カイラル剤の添加量はブルー相のブラッグ回折波長（ブラッグ反射波長）が３８０ｎｍ以下に現れるように調整したものである。なお、ブラッグ回折波長は可視領域である３８０ｎｍ以上６８０ｎｍ以下に現れなければよく、６８０ｎｍ以上に現れるようにカイラル剤の量を調整してもよい。 First, in order to form a blue phase liquid crystal layer stabilized with a polymer in the first liquid crystal layer BP1, nematic liquid crystals JC1041-XX (Nisso) and 5CB (Aldrich), and further, as a chiral agent, a chemical formula A mixed liquid crystal to which a binaphthyl derivative as shown in (1) is added is prepared.

The composition ratio (JC1041-XX / 5CB / binaphthyl derivative) in the mixed liquid crystal was 48/48/4 (mol%). The amount of the chiral agent added is adjusted so that the Bragg diffraction wavelength (Bragg reflection wavelength) of the blue phase appears at 380 nm or less. The Bragg diffraction wavelength does not have to appear in the visible region of 380 nm or more and 680 nm or less, and the amount of the chiral agent may be adjusted so that it appears in the range of 680 nm or more.

  EHA (Aldrich), which is a monofunctional monomer, and RM257 (Merck), which is a multifunctional monomer, were added as photopolymerizable monomers for forming a polymer network in the mixed liquid crystal. The composition ratio (EHA / RM257) of the mixed monomer was 70/30 (mol%). The composition ratio (mixed liquid crystal / mixed monomer) of the mixed liquid crystal to which the chiral agent was added and the mixed monomer was 93.7 / 6.3 (mol%). Furthermore, DMPAP (Aldrich) was used as a photopolymerization initiator, and 10 (wt%) was added to the mixed monomer to prepare a mixed solution for use in the first liquid crystal layer BP1.

  Next, also in the second liquid crystal layer BP2, a blue phase liquid crystal layer stabilized with a polymer is formed. In the present embodiment, except that a chiral agent that induces twist in the opposite direction to the chiral agent contained in the blue phase liquid crystal of the first liquid crystal layer BP1 is used, as in the case of the first liquid crystal layer BP1, A mixed solution for use in the second liquid crystal layer BP2 was prepared.

  These mixed solutions were separately sealed in a vacuum, and each substrate was sealed with a sealant made of an ultraviolet curable resin.

After sealing, the temperature is raised to a temperature at which the mixed solution sealed in the first liquid crystal layer BP1 and the second liquid crystal layer BP2 becomes an isotropic phase, and is kept constant in a temperature range in which BPI is expressed. By irradiating ultraviolet light of .5 mWcm ⁻² (365 nm), the first liquid crystal layer BP1 and the second liquid crystal layer BP2 were formed to include a blue phase liquid crystal stabilized with a polymer. Thus, the liquid crystal display device 1 in which the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are stacked is obtained. In addition, since the chiral agent contained in the first liquid crystal layer BP1 and the chiral agent contained in the second liquid crystal layer BP2 use a chiral agent exhibiting reverse twist, they exhibit optical rotation in opposite directions. Contrast will be improved.

  Note that the liquid crystal compound that can be used in the first liquid crystal layer BP1 and the second liquid crystal layer BP2 of the present embodiment may be a compound that exhibits a nematic phase or a smectic phase at an arbitrary temperature. Two or more kinds of liquid crystal compounds may be used, but it is preferable to exhibit nematic liquid crystal properties after mixing. The chiral agent may be a liquid crystalline compound or a non-liquid crystalline compound as long as the spiral orientation of the liquid crystals contained in the first liquid crystal layer BP1 and the second liquid crystal layer BP2 is reversed. Good. However, it is preferable to have a structure similar to that of the liquid crystal compound from the viewpoint of the compatibility between the liquid crystal compound and the chiral agent.

  The first liquid crystal layer BP1 or the second liquid crystal layer BP2 may be a mixed solution prepared by adding a plurality of chiral agents. When a chiral agent having a positive temperature dependency and a negative chiral agent are mixed and used, the temperature dependency becomes small. However, for example, when two chiral agents that are reversely twisted with each other are added, it is necessary to adjust the amount of the two chiral agents added to induce orientation twist in either the right twist or the left twist. This is because alignment twist is induced in the first liquid crystal layer BP1 and the second liquid crystal layer BP2 so as to be opposite to each other. As a result, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 can exhibit optical rotation so as to be in opposite directions.

  In the above, the temperature range showing the blue phase is expanded by allowing the liquid crystal composition to contain a monofunctional monomer and a polyfunctional monomer and performing a polymerization reaction. The monofunctional monomer is a non-liquid crystalline or liquid crystalline compound having one polymerizable functional group. For example, acrylic acid esters, methacrylic acid esters, and acrylic acid alkyl esters are preferable. The polyfunctional monomer is a compound having two or more polymerizable functional groups, and for example, liquid crystalline diacrylate is preferable. In the present embodiment, blue phase liquid crystal in which a blue phase is stabilized by forming a polymer chain by polymerization of monomers in this way is enclosed in the first liquid crystal layer BP1 and the second liquid crystal layer BP2. . A stabilizer may be used to stabilize the blue phase structure. In the present embodiment, the polymer chain is stabilized in order to widen the blue phase expression temperature range, but the temperature range expansion method is not limited to this.

  Further, as shown in FIG. 4, the first substrate SUB1 includes a thin film transistor TFT, a wiring electrode GL, and a pixel electrode PX on the substrate 101. The substrate 101 is preferably highly transparent, and a glass substrate is used, but quartz, ceramic, or plastic may be used. A resin substrate such as PET (polyethylene terephthalate), PC (polycarbonate), or polymethyl methacrylate can also be used. In the pixel, the pixel electrode PX and the common electrode CT are formed in a comb shape by a transparent conductive layer made of ITO (ITO: Indium Tin Oxide). In addition, a transparent electrode such as InZnO (Indium Zinc Oxide) can be used. An insulating layer 102 made of silicon nitride or an organic material was formed between the wiring electrode GL and the pixel electrode PX, and insulating layers 104 and 105 made of silicon nitride or an organic material were further formed thereon. In the present embodiment, the common electrode CT and the pixel electrode PX made of ITO have a thickness of 77 nm. At this time, the distance Pg between the pixel electrode PX and the common electrode CT is set to 10.0 μm.

  The second substrate SUB2 includes a black matrix 207, a color filter 208G, and an overcoat layer 206. After the black matrix 207 and the color filter 208G are formed on the second substrate SUB2, the second substrate SUB2 is overcoated for planarization. The coating layer 206 was applied and baked. The substrate 201 is preferably transparent, and a glass substrate is used. However, quartz, ceramic, plastic, etc. can also be used. By disposing the black matrix 207, unnecessary light leakage is blocked. Further, the color filter 208G has different colors between adjacent pixels in the horizontal direction.

  The overcoat layer 206 may be any material that can be formed on the color filter 208G, is transparent in the visible region, and can be applied to the alignment film forming process and the liquid crystal panel forming process. Organic materials such as phenol resin, polyimide resin, silicon-containing polyimide, and polyimide siloxane film can be applied. Smooth and tough, transparent, high heat and light resistance, no deterioration such as yellowing and whitening over a long period of time, chemical resistance such as water resistance, solvent resistance, acid resistance and alkali resistance In particular, polyimide resins, silicon-containing polyimides, polyimide resins such as polyimide siloxane, epoxy resins, and acrylic resins are preferable.

  The third substrate SUB3 is a glass substrate similar to the first substrate SUB1 and the second substrate SUB2, but may be quartz, ceramic, or plastic. A resin substrate such as PET (polyethylene terephthalate), PC (polycarbonate), or polymethyl methacrylate can also be used. Then, a cell is assembled with these three substrates with a spacer and a peripheral sealant interposed therebetween. Thereafter, as described above, the mixed solution is separately sealed between the first substrate SUB1 and the third substrate SUB3, and between the third substrate SUB3 and the second substrate SUB2, and is made of an ultraviolet curable resin. Each substrate is sealed with a sealant. Liquid crystal display device 1 in which a layer containing a blue phase liquid crystal stabilized with a polymer is laminated on first liquid crystal layer BP1 and second liquid crystal layer BP2 separately by irradiating ultraviolet light after sealing. Is obtained.

  In the present embodiment, the thickness of the first liquid crystal layer BP1 and the second liquid crystal layer BP2 is 25 μm. In consideration of the influence of the light leakage due to the difference in the thickness of the liquid crystal layer, the thicknesses of the liquid crystal layers BP1 and BP2 are made equal in this embodiment, but the black transmittance is reduced and the contrast is improved even at different thicknesses. Can do. Further, in the present embodiment, the phase difference independent of the thickness of the liquid crystal layer is obtained by increasing the thickness of the liquid crystal layer.

  Note that an alignment film may be formed between the first liquid crystal layer BP1 and the second liquid crystal layer BP2 and each substrate. The alignment film may be formed on one or both of the interface between the first liquid crystal layer BP1 and the first substrate SUB1, the interface between the first liquid crystal layer BP1 and the third substrate SUB3. The same applies to the second liquid crystal layer BP2. The alignment film may be formed for making the blue phase liquid crystal monodomain.

  In order to prevent uneven composition of the blue phase liquid crystal in the first liquid crystal layer BP1 and the second liquid crystal layer BP2 and segregation of the composition, within the range of the solubility parameter (SP value) of the component contained in each liquid crystal layer. A film made of the contained material may be provided at the interface with the substrate in contact with the liquid crystal layer. Examples of the film that prevents uneven composition include diethoxymethylphenylsilane and polystyrene. In the case where an alignment film is formed, a film that prevents uneven composition may be formed at the interface between the alignment film and the liquid crystal layer.

  In order to improve viewing angle characteristics, the liquid crystal display device 1 may include a constituent member such as a retardation plate. In addition, the optical rotation which arises in 1st liquid crystal layer BP1 and 2nd liquid crystal layer BP2 can be measured using a phase difference measuring apparatus (AxoScan by Axometrics), for example. In this embodiment, the optical rotatory power generated in the first liquid crystal layer BP1 and the like is determined by evaluating with light having a wavelength of 550 nm at 25 ° C., which is a use temperature of the liquid crystal display device. Note that the optical rotation angle by the second liquid crystal layer BP2 is preferably at least half the optical rotation angle by the first liquid crystal layer BP1.

  In the present embodiment, the electrode structure is such that a lateral electric field that is an electric field in the in-plane direction of the first substrate SUB1 can be effectively applied to the first liquid crystal layer BP1. The electrode structure is preferably a structure that effectively applies a lateral electric field, but may be any electrode structure that has an in-plane direction component. The shape of the electrode is not limited to a shape such as a comb-teeth shape, a point electrode, or a wall electrode. In addition, in the cross-sectional view cut in the direction perpendicular to the substrate, the shape of the electrode is not limited, such as a rectangle, a square, or a trapezoid.

  As a result of driving the liquid crystal display device 1, as shown in FIG. 5, the liquid crystal display device has a substantially similar structure except that the liquid crystal layer is one layer (only the first liquid crystal layer BP1 is used). Contrast (ratio of transmittance in white display and black display) was improved.

  In the present embodiment, no electric field is applied to the second liquid crystal layer BP2, but an electric field is applied to the second liquid crystal layer BP2 as the electric field is applied to the first liquid crystal layer BP1. Also good. When an electric field is applied to the first liquid crystal layer BP1, birefringence is induced in the first liquid crystal layer BP1, and the light of the backlight 15 transmits the polarizing plate PL2 to display white.

  In the present embodiment, the blue phase liquid crystal sealed in each is prepared so that the peak of the Bragg diffraction wavelength indicated by the first liquid crystal layer BP1 and the second liquid crystal layer BP2 is 380 nm or less. In one of the first liquid crystal layer BP1 and the second liquid crystal layer BP2, a peak of the Bragg diffraction wavelength derived from the blue phase structure may appear at 380 nm or more and 680 nm or less as in other embodiments described later. Although it is good, it is desirable to prevent the peak of the Bragg diffraction wavelength from appearing at 380 nm to 680 nm in order to reduce the luminance of black display.

  In the present embodiment, the first liquid crystal layer BP1 that performs display control of a pixel by applying a lateral electric field, and the second liquid crystal layer BP2 that has an optical rotation in the opposite direction to the first liquid crystal layer BP1 are provided. Be placed. However, for example, a liquid crystal layer having optical rotation in the same direction as the second liquid crystal layer BP2 is further disposed between the polarizing plates PL1 and PL2, and the effect of the optical rotation of the first liquid crystal layer BP1 is influenced by two or more. The liquid crystal layer may be reduced. It suffices that at least one liquid crystal layer exhibiting optical rotation in the opposite direction is included in the first liquid crystal layer BP1 for controlling display of pixels. As a result, light leakage of light having optical rotation generated after passing through the liquid crystal layer can be reduced, and the black transmittance can be reduced. In the present embodiment, the backlight 15 is disposed on the first substrate SUB1 side, and the first liquid crystal layer BP1 for controlling display of pixels is a liquid crystal layer on the side close to the backlight 15. ing. Thereby, since the scattering of the light incident on the first liquid crystal layer BP1 is reduced, the luminance of black display is preferably reduced. In other words, even when there are two or more other liquid crystal layers, it is preferable that the first liquid crystal layer BP1 that controls the display of the pixels is disposed on the side closest to the backlight 15.

[Second Embodiment]
In the first embodiment, TFTs are formed on the first substrate SUB1, and the horizontal electric field is applied only to the first liquid crystal layer BP1 to perform pixel display control. However, the second embodiment Then, a horizontal electric field is applied to both the first liquid crystal layer BP1 and the second liquid crystal layer BP2 to perform pixel display control. Except for this point, the liquid crystal display device according to the second embodiment is the same as the liquid crystal display device 1 according to the first embodiment, and the description of the same points will be omitted as appropriate.

  FIG. 6 is a diagram schematically showing a cross section of the liquid crystal display panel 11 in the second embodiment. As shown in the figure, on the first substrate SUB1 and the third substrate SUB3, TFTs, pixel electrodes PX formed in a comb shape, and a common electrode CT formed in a comb shape are arranged. . Then, a horizontal electric field is simultaneously applied to the first liquid crystal layer BP1 and the second liquid crystal layer BP2, and display control of the pixels is performed. The optical rotation that the first liquid crystal layer BP1 exhibits when no electric field is applied and the optical activity that the second liquid crystal layer BP2 exhibits when no electric field is applied are opposite to each other. Thereby, the amount of retardation with respect to the linearly polarized light transmitted through the first polarizing plate PL1 is increased, and the luminance at the time of white display is easily improved. In addition, since the liquid crystal layer to which a lateral electric field is applied is dispersed, image sticking is alleviated and the durability of the liquid crystal display device is improved. In the second embodiment, the counter electrode CT is arranged on the second liquid crystal layer BP2 side of the third substrate SUB3 to generate a lateral electric field, but the second liquid crystal layer of the second substrate SUB2 is used. A TFT, a pixel electrode PX, and the like may be provided on the BP2 side.

[Third Embodiment]
In the second embodiment, TFTs are arranged on the first substrate SUB1 and the third substrate SUB3, and a lateral electric field is applied to the first liquid crystal layer BP1 and the second liquid crystal layer BP2. However, in the third embodiment, a lateral electric field is applied to the two liquid crystal layers by the TFT disposed on the third substrate SUB3. Except for this point, the liquid crystal display device according to the third embodiment is the same as the liquid crystal display device according to the first embodiment, and the description of the same points will be omitted as appropriate.

  FIG. 7 is a diagram schematically showing a cross section of the liquid crystal display panel 11 in the third embodiment. As shown in the figure, TFTs are arranged on the third substrate SUB3, and an insulating layer 302 made of silicon nitride or organic material is formed between the wiring electrodes GL and the comb-like pixel electrodes PX. Insulating layers 304 and 305 made of silicon nitride or organic matter are further formed on the insulating layer 302. The insulating layer 305 is also formed on the first liquid crystal layer BP1 side of the substrate 301, and the common electrode CT is formed in a comb shape on the insulating layers 305 on both sides. The substrate 301 is preferably a thin substrate so that the electric field strength is evenly applied to the top and bottom of the substrate, and may be formed of a material having insulating properties and light transmission properties such as a polymer film.

  By doing so, the number of TFTs can be reduced as compared with the case of the second embodiment, so that the cost can be reduced.

[Fourth Embodiment]
In the second embodiment, the first substrate SUB1 and the third substrate are used to control the display of pixels by applying a lateral electric field to both the first liquid crystal layer BP1 and the second liquid crystal layer BP2. A TFT was placed on SUB3. In the fourth embodiment, the second electrode is that the common electrode CT2 is arranged on the third substrate SUB3 side of the first liquid crystal layer BP1 and on the second substrate SUB2 side of the second liquid crystal layer BP2. It is different from the embodiment. Except for this point, the liquid crystal display device according to the fourth embodiment is the same as the liquid crystal display device according to the second embodiment, and the description of the same points will be omitted as appropriate.

  FIG. 8 is a diagram schematically showing a cross section of the liquid crystal display panel 11 in the fourth embodiment. As shown in the figure, a first common electrode CT1 is formed in a comb shape on the insulating layers 105 and 305 in the first substrate SUB1 and the third substrate SUB3. A flat common electrode CT2 is formed on the substrate 301 of the third substrate SUB3 and the overcoat layer 206 of the second substrate SUB2. Thereby, the electric field having the in-plane direction component can be distributed more uniformly in the depth direction of the liquid crystal layer than in the case of the second embodiment.

[Fifth Embodiment]
The liquid crystal display device according to the fifth embodiment has the same configuration as the liquid crystal display device according to the first embodiment, except that the thickness of the second liquid crystal layer BP2 is 13.0 μm. This is as shown in the first embodiment. The peak wavelength of the Bragg diffracted light or the lattice size of BP1 of the first liquid crystal layer BP1 and the second liquid crystal layer BP2 is equal. When forming a blue phase liquid crystal stabilized with a polymer by making the thickness of the second liquid crystal layer BP2 thinner than the thickness of the first liquid crystal layer BP1, the irradiation intensity in the thickness direction in ultraviolet light irradiation Further, the unevenness of the irradiation amount was reduced, and a uniform blue phase could be formed.

  In the fifth embodiment, the thickness of the second liquid crystal layer BP2 is reduced. However, the thickness of the first liquid crystal layer BP1 or both the liquid crystal layers BP1 and BP2 may be reduced.

[Sixth Embodiment]
In the liquid crystal display device according to the sixth embodiment, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are separated via the separation film PE, and the first substrate SUB1 and the second substrate SUB2 are separated. Is arranged. Except for this point, the liquid crystal display device 1 is the same as the liquid crystal display device 1 according to the first embodiment.

  FIG. 9 is a diagram schematically showing a cross section of the liquid crystal display panel 11 in the sixth embodiment. As shown in the figure, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are stacked between two substrates via a separation film PE. In the case of such an element configuration, the third substrate SUB3 becomes unnecessary as compared with the first embodiment, and the member cost can be reduced.

  Hereinafter, a method of forming the first liquid crystal layer BP1 and the second liquid crystal layer BP2 with the separation film PE interposed therebetween will be described.

  First, in order to form the first liquid crystal layer BP1, a mixed solution similar to that of the first embodiment is injected between the first substrate SUB1 and the auxiliary substrate coated with the release resin, and irradiated with ultraviolet light. To form a first liquid crystal layer BP1 containing a blue phase liquid crystal stabilized with a polymer. As the peelable resin, a resin having poor adhesion to polyethylene, polyethylene terephthalate, polypropylene, nylon, silicone rubber, fluorine resin, or the like is used.

  Next, in the same procedure, a mixed solution similar to that in the first embodiment (including the first liquid crystal layer BP1 and a counter-twist chiral agent) is injected between the second substrate SUB2 and the auxiliary substrate. A second liquid crystal layer BP2 is formed. After that, the auxiliary substrate is peeled off, and the first substrate SUB1 and the second substrate SUB2 are disposed to face each other with the separation film PE interposed therebetween, thereby bonding the first liquid crystal layer BP1 and the second substrate between the two substrates. A liquid crystal layer BP2 is formed. A 2.5 μm PET film (manufactured by Toray Industries, Inc.) was laminated on the separation membrane.

  By providing the first liquid crystal layer BP1 and the second liquid crystal layer BP2 via the separation film PE, the two liquid crystal layers are in direct contact with each other, so that the effect of the chiral agent in the vicinity of the boundary is hardly offset. The separation membrane PE may be a membrane made of a polymer. Examples of the method for forming a film include a method of separating a polymer and a liquid crystal, and include a phase separation method accompanying polymerization, a phase separation method using heat, a separation method accompanying evaporation of a solvent, and the like. However, the method is not limited to these methods as long as the separation membrane PE is formed. The separation membrane PE may be formed independently as in the PET film of this embodiment, or may be a layer formed by separating a polymer and a liquid crystal. Further, when the separation membrane PE is used, the yield is improved and the stability and reliability are improved as compared with the case where the interface between the two liquid crystal layers is formed in contact.

[Seventh Embodiment]
In the liquid crystal display device according to the seventh embodiment, the interfaces between the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are brought into contact with each other, and both liquid crystal layers are placed between the first substrate SUB1 and the second substrate SUB2. Is arranged. In the liquid crystal display device according to the seventh embodiment, the separation film PE is not disposed, and the materials of the blue phase liquid crystal and the polymer chain contained in the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are different. . Except for this point, the liquid crystal display device according to the sixth embodiment is the same as the liquid crystal display device, and a description thereof will be omitted as appropriate.

First, FIG. 10 is a diagram for explaining a state of a blue phase liquid crystal stabilized by a polymer chain. The blue phase liquid crystal has a lattice structure, and the expression temperature range is expanded by being stabilized by the polymer chain. The two liquid crystal layers can be phase-separated by defining the molecular size of the liquid crystal composition and the size of the polymer chain formed in the disclination, and can be laminated while the interfaces are in contact with each other. As shown in FIG. 10, the blue phase I exhibits body-centered cubicity, where the lattice size of the blue phase is a, the radius of the liquid crystal cylinder is R, and the molecular size in the minor axis direction of the polymer chain is b. The relationship between these three parameters must satisfy equation (1).
(A-8R) / 2 ≧ b (1)

In addition, the blue phase II shows a simple cubic symmetry and must satisfy the formula (2).
(A-4R) / 2 ≧ b (2)

  By adjusting the size of the polymer chain and the concentration of the chiral agent and defining the lattice size of the blue phase of the two liquid crystal layers in contact with different sizes, the liquid crystal cylinder can easily enter the polymer chain. It will be different and phase separation is possible. When forming a polymer chain, for example, the block copolymer may be formed so that one of the first liquid crystal layer BP1 and the second liquid crystal layer BP2 satisfies the formula (1).

  FIG. 11 is a diagram schematically showing a cross section of the liquid crystal display panel 11 in the seventh embodiment. In the present embodiment, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are mixed solutions that have different lattice sizes and polymer chain sizes and are adjusted so that the Bragg diffraction wavelength appears at 380 nm or less. . As in the first embodiment, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are reduced in the influence of optical rotation by using a chiral agent that exhibits twist in opposite directions. In the liquid crystal display device according to the seventh embodiment, the horizontal electric field generated from the first substrate SUB1 is distributed to the second liquid crystal layer BP2 as compared with the case of the sixth embodiment in which the separation film PE is present. It becomes easy to let you.

  As a method of phase separation, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are made to deteriorate by reducing the compatibility of each mixed solution forming the first liquid crystal layer BP1 and the second liquid crystal layer BP2. You may make it contact.

[Eighth Embodiment]
The liquid crystal display device according to the eighth embodiment is common to the sixth embodiment in that the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are separated from each other via the separation film PE. However, the liquid crystal display device according to the eighth embodiment is different from the sixth embodiment in that the common electrode CT2 is further arranged on the overcoat layer 206 of the second substrate SUB2. Other than this point, the liquid crystal display device according to the sixth embodiment is the same as the liquid crystal display device according to the sixth embodiment.

  FIG. 12 is a simplified diagram schematically showing a cross section of the liquid crystal display panel 11 in the eighth embodiment. As shown in the figure, common electrodes CT1 and CT2 are formed in a comb-tooth shape on the liquid crystal layer side of the first substrate SUB1 and the second substrate SUB2, respectively. The common electrode CT2 has a portion formed in a comb shape along the common electrode CT1 and a portion formed along the black matrix 207 at a position immediately above the common electrode CT1. Then, by applying an electric field in an oblique direction from the pixel electrode PX to the common electrode CT2, white transmittance is improved and image sticking is reduced as compared with the case of only the common electrode CT1. In addition, since the common electrode CT2 has a portion formed along the black matrix 207, the liquid crystal near the black matrix 207 is also driven. At this time, the width of the comb-tooth portion of the common electrode CT2 is such that the portion formed along the common electrode CT1 is thicker than the common electrode CT1, and the portion formed along the black matrix 207 is wider than the black matrix 207. Also formed thin.

  Although the separation membrane PE exists in this embodiment, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 may be brought into contact with each other as in the case of the seventh embodiment. In this case, the mixed solution used for the two liquid crystal layers is adjusted to have different lattice sizes and polymer chain sizes as in the case of the seventh embodiment. In the present embodiment, the common electrode CT2 is formed in a comb-teeth shape. However, the white transmittance may be improved by forming the common electrode CT2 in a flat electrode (solid electrode).

[Ninth Embodiment]
The liquid crystal display device according to the ninth embodiment is common to the sixth embodiment in that the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are separated from each other via the separation film PE. However, the liquid crystal display device according to the ninth embodiment differs from that of the sixth embodiment in that the color filter 108G and the like are formed on the first substrate SUB1 together with the TFT and the second substrate SUB2 is a transparent substrate. Is different. Except for this point, the ninth embodiment is substantially the same as the sixth embodiment, and a description thereof will be omitted.

  FIG. 13 is a diagram schematically showing a cross section of the liquid crystal display panel 11 in the ninth embodiment. As shown in the figure, a black matrix 107, a color filter 108G, an overcoat layer 106, a pixel electrode PX, a common electrode CT, and the like are formed on the first substrate SUB1.

  Irradiation of ultraviolet light in the step of forming a blue phase liquid crystal stabilized with a polymer when forming the second liquid crystal layer BP2 by providing the wiring electrode GL or the like on the second substrate SUB2 side. Is reduced. This is because the mixed solution is sealed between the second substrate SUB2 and the auxiliary substrate and irradiated with ultraviolet light as in the case of the sixth embodiment. The thicknesses of the first liquid crystal layer BP1 and the second liquid crystal layer BP2 were each 13 μm.

[Tenth embodiment]
In the liquid crystal display device according to the first embodiment, the color filter 208G is formed on the second substrate SUB2. On the other hand, in the liquid crystal display device according to the tenth embodiment, coloring is performed by separately encapsulating two types of liquid crystal materials as the second liquid crystal layer BP2 via the sealing material SE instead of the color filter 208G. . Except for this point, the tenth embodiment is the same as the liquid crystal display device of the first embodiment, and thus description thereof will be omitted as appropriate.

  FIG. 14 is a diagram schematically showing a cross section of the liquid crystal display panel 11 according to the tenth embodiment. The second liquid crystal layer BP2 includes two types of liquid crystal materials, a first liquid crystal material and a second liquid crystal material. The first liquid crystal material and the second liquid crystal material are respectively enclosed in the first sealing region BP2a and the second sealing region BP2b that are partitioned separately in the in-plane direction of the second substrate SUB2. The first sealing region BP2a in which the first liquid crystal material is sealed and the second sealing region BP2b in which the second liquid crystal material is sealed are arranged in parallel (in parallel) with the second substrate SUB2. The

  In the present embodiment, the sealing material SE extends in the column direction of the display area DA, and the first sealing area BP2a and the second sealing area BP2b are partitioned for each pixel column. As will be described later, the first sealing region BP2a is filled with a first liquid crystal material that is a blue phase liquid crystal having peak wavelengths of Bragg diffracted light at 460 nm and 650 nm, and the second sealing region BP2b has a peak wavelength. Is filled with a second liquid crystal material which is a blue phase liquid crystal having 550 nm.

The blue phase liquid crystal is colored by reflected light derived from Bragg reflection depending on the orientation of the crystal with respect to incident light. The case where two reflection peak wavelengths exist in the visible wavelength region occurs because the reflection peak wavelength is λhkl = 2nd / (h2 + k2 + l2) ^{1 /} using the refractive index n of the liquid crystal, the lattice constant d, and the Miller index (hkl). ^This is because it depends on ² . Therefore, a reflection peak on the short wavelength side occurs at a wavelength that is 1 / 1.4 times the reflection peak on the long wavelength side of the two reflection peaks.

  Hereinafter, two kinds of mixed solutions used for the second liquid crystal layer BP2 will be described.

  First, as the first liquid crystal material, JC1041-XX and 5CB are nematic liquid crystals, and ZLI-4572 is heated and mixed as a chiral agent that is counter-twisted with the blue phase liquid crystal sealed in the first liquid crystal layer BP1. A mixed liquid crystal was used. Each ratio (JC1041-XX / 5CB / ZLI-4572 (mol%)) was 48.0 / 48.0 / 4 (mol%). Next, EHA and RM257 were added to the mixed liquid crystal as monomers. The monomer composition ratio (EHA / RM257 (mol%)) is 70/30 (mol%). Further, DMPAP was added as a photopolymerization initiator to obtain a uniform mixed solution. The monomer content in the mixed solution was 6.3 (mol%), and DMPAP was adjusted to 10 (wt%) with respect to the mixed monomer.

  Next, the second liquid crystal material is JC1041-XX and 5CB as nematic liquid crystal, and R811 (Merck) is heated and mixed as a chiral agent that is counter-twisted with the blue phase liquid crystal sealed in the first liquid crystal layer BP1. Thus, a mixed liquid crystal was obtained. Each ratio (JC1041-XX / 5CB / R811 (mol%)) was 32.5 / 32.5 / 35 (mol%). Next, EHA and RM257 were added as monomers to the mixed liquid crystal. The monomer composition ratio (EHA / RM257 (mol%)) is 70/30 (mol%). Furthermore, DMPAP was added to the photopolymerization initiator to obtain a uniform mixed solution. The monomer content in the mixed solution was 6.3 (mol%), and DMPAP was adjusted to 10 (wt%) with respect to the mixed monomer.

  Then, the two kinds of mixed solutions are vacuum-injected into the panel in an isotropic state. Specifically, a member (sealing material SE) for partitioning is formed on the overcoat layer 206 of the second substrate SUB2, and the second substrate SUB2 and the third substrate SUB3 are assembled. An injection port for injecting the mixed solution containing the first liquid crystal material and an injection port for injecting the mixed solution containing the second liquid crystal material are separately formed on the side surfaces facing each other. This injection port is formed for each row partitioned by the sealing material SE. Then, the mixed solution for the first liquid crystal material and the mixed solution for the second liquid crystal material are vacuum-injected separately from the two side surfaces. After each mixed solution is injected, each injection port is sealed.

  The mixed solution of the first liquid crystal layer BP1 is the same as that of the first embodiment, and an injection port for injecting the mixed solution is also provided on any side surface of the cell in which three substrates are assembled. Then, the mixed solution was injected and sealed after the injection.

  Then, by adjusting the type and concentration of the chiral agent as described above, the blue phase expression temperature of the mixed liquid crystal in the first sealing region BP2a and the second sealing region BP2b formed on the same plane, ie, high Aligned UV light irradiation temperature when forming blue liquid crystal stabilized with molecules. The first liquid crystal material in the first sealing region BP2a has two peak wavelengths of Bragg diffracted light in the visible wavelength region (400 nm to 700 nm). Further, the second liquid crystal material in the second sealing region BP2b has one peak wavelength of Bragg diffracted light. Specifically, the first liquid crystal material has peak wavelengths of Bragg diffracted light at 460 nm and 650 nm, and is colored red and blue. The second liquid crystal material has a peak wavelength of Bragg diffracted light at 550 nm and is colored green.

  Accordingly, since the second liquid crystal layer BP2 can express red, green, and blue, the liquid crystal display panel 11 may not have a color filter. Further, in the present embodiment, three consecutive rows form one set, two of the three rows are two first sealing regions BP2a, and the remaining one row is one second sealing region BP2b. Correspondingly, the first sealing region BP2a and the second sealing region BP2b are regularly arranged. That is, in the present embodiment, the white pixel is configured by three pixels, that is, two pixels in the first sealing region BP2a and one pixel in the second sealing region BP2b.

  In the liquid crystal display device according to the present embodiment, the backlight 15 periodically emits light corresponding to each of the peak wavelengths. Specifically, the backlight 15 periodically emits light in red (light emission corresponding to a peak wavelength of 650 nm), green (light emission corresponding to a peak wavelength of 550 nm), and blue (light emission corresponding to a peak wavelength of 460 nm). Light is supplied to the liquid crystal display panel 11. The display of the pixels of the liquid crystal display panel 11 is controlled in accordance with the light emission timing of the backlight 15. Specifically, in accordance with the timing at which the backlight 15 emits red light, display control is performed on some pixels (specifically, half of the pixels) among the pixels in which the first liquid crystal material is sealed, The remaining part of the pixels in which the first liquid crystal material is sealed is controlled according to the timing of emitting blue light, and the second liquid crystal material is sealed in accordance with the timing of emitting green light. Display control is performed on the pixels.

  In the present embodiment, the backlight 15 is controlled to emit light as described above, but the backlight 15 emits light corresponding to at least two peak wavelengths of the first liquid crystal material at different timings. What should I do? For example, the backlight 15 may always emit light corresponding to the peak wavelength of 550 nm and periodically emit light corresponding to the peak wavelengths of 460 nm and 650 nm. In such a case, the intensity of light emission corresponding to the peak wavelength of 550 nm may be weaker than light emission corresponding to other peak wavelengths.

  Since the second liquid crystal layer BP2 (the first sealing region BP2a and the second sealing region BP2b) has an optical rotation that is opposite to that of the first liquid crystal layer BP1, the second liquid crystal layer BP2 By disposing, the transmittance of black display can be reduced.

  In the tenth embodiment, no color filter is provided on the second substrate SUB2. However, a color filter may be provided to further improve color reproducibility. Further, in order to improve the transmittance in white display or prevent deterioration due to image sticking, a TFT, a pixel electrode PX, and a common electrode CT are further formed on the third substrate SUB3, and a horizontal electric field is formed on the second liquid crystal layer BP2. May be applied.

[Eleventh embodiment]
Like the liquid crystal display device according to the tenth embodiment, the liquid crystal display device according to the eleventh embodiment is colored by separately encapsulating two types of liquid crystal materials in the second liquid crystal layer BP2. is there. However, the liquid crystal display panel 11 in the eleventh embodiment does not have the third substrate SUB3, and the blue phase liquid crystal contained in the second liquid crystal layer BP2 and the blue liquid crystal contained in the first liquid crystal layer BP1. The phase liquid crystals contact each other with an interface. In this respect, the liquid crystal display device according to the eleventh embodiment is different from the liquid crystal display device according to the tenth embodiment, but the configuration other than this point is the same as that of the tenth embodiment, so that the description will be appropriately given. Shall be omitted.

  FIG. 15 is a diagram schematically showing a cross section of the liquid crystal display panel 11 according to the eleventh embodiment. As described above, the blue phase liquid crystal included in the first liquid crystal layer BP1, the blue phase liquid crystal included in the first sealing region BP2a, and the blue phase liquid crystal included in the second sealing region BP2b have different Bragg diffraction wavelengths. (Lattice size), the ease of entering the liquid crystal cylinder into the polymer chain is different. Therefore, as shown in FIG. 14, phase separation is possible even when no separation membrane is provided.

  As a method for injecting the mixed solution containing the first liquid crystal material into the first sealing region BP2a and the mixed solution containing the second liquid crystal material into the second sealing region BP2b, respectively, in the tenth embodiment. What is necessary is just to carry out vacuum injection | pouring similarly to 10th Embodiment using an auxiliary | assistant board | substrate instead of the used 3rd board | substrate SUB3. Thereafter, the auxiliary substrate into which the first liquid crystal layer BP1 is injected and the auxiliary substrate into which the second liquid crystal layer BP2 (the first sealing region BP2a and the second sealing region BP2b) are injected are peeled and arranged to face each other. The first liquid crystal layer BP1 and the second liquid crystal layer BP2 are formed between the two substrates.

  The thicknesses of the first liquid crystal layer BP1 and the second liquid crystal layer BP2 were each 13 μm.

[Twelfth embodiment]
The liquid crystal display device according to the twelfth embodiment is substantially the same as the liquid crystal display device according to the sixth embodiment, except that the liquid crystal sealed in the second liquid crystal layer BP2 is a liquid crystal exhibiting a chiral nematic phase. is there. The description of the same points will be omitted as appropriate.

  In the liquid crystal display device according to the twelfth embodiment, a planar nematic phase having a chiral agent that is counter-twisted with the first liquid crystal layer BP1 is formed in the second liquid crystal layer BP2. Then, a horizontal alignment film was applied to the second substrate SUB2 and auxiliary substrate in contact with the second liquid crystal layer BP2, and a rubbing process was performed, so that the substrates were assembled in an antiparallel manner.

  Hereinafter, a mixed solution used for the second liquid crystal layer BP2 is shown.

  First, HA5607XX (Chisso) having a higher melting point than these two types of liquid crystals was mixed with JC1041-XX, 5CB. By mixing a liquid crystal having a high melting point, a chiral nematic phase was developed in the second liquid crystal layer BP2 at 25 ° C. assumed as a use temperature (the first liquid crystal layer BP1 exhibits a blue phase). The mixing ratio of liquid crystals (JC1041-XX / 5CB / HA5607XX) is 30/30/40 (mol%). Further, the chiral agent was added by 4.0 (mol%) using the chemical formula (1) of the binaphthyl derivative that induces twist in the opposite direction to that of the chiral agent contained in the blue phase liquid crystal of the first liquid crystal layer BP1. . By aligning the addition amounts of the chiral agents in the first liquid crystal layer BP1 and the second liquid crystal layer BP2, liquid crystal layers having the same chiral pitch can be obtained. The chiral agent represented by the chemical formula (1) is a chiral agent in which the chiral pitch becomes longer as the temperature increases. Therefore, in order to reduce the temperature dependence of the chiral pitch, another chiral agent that shortens the chiral pitch as the temperature increases may be added. As in the sixth embodiment, the first liquid crystal layer BP1 and the second liquid crystal layer BP2 are respectively formed on the first substrate SUB1 and the second substrate SUB2 using an auxiliary substrate, and after separation, a separation layer is formed. Pasted through. The separation layer was laminated with a 2.5 μm PET film (Toray Industries, Inc.). The layer thickness of the second liquid crystal layer BP2 is not necessarily the same as that of the first liquid crystal layer BP1, and a thin film is preferable in consideration of the influence of transmittance and driving voltage. In the present embodiment, the first liquid crystal layer BP1 is 13 μm, the second liquid crystal layer BP2 is 5 μm, and the second liquid crystal layer BP2 is thinner than the first liquid crystal layer BP1.

  As the second liquid crystal layer BP2, the liquid crystal layer to be laminated is a blue phase liquid crystal if the liquid crystal layer to be stacked is from the viewpoint of simplicity of parameter control for eliminating optical rotation. As a result, it is preferable that the second liquid crystal layer BP2 has reverse optical rotation. From the viewpoint of simplification of the manufacturing process, as in the twelfth embodiment, the liquid crystal included in the second liquid crystal layer BP2 is a liquid crystal exhibiting a chiral nematic phase, and the second liquid crystal layer BP2 is reversely rotated. It is good to have sex. Similarly, from the viewpoint of simplifying the manufacturing process, the liquid crystal included in the second liquid crystal layer BP2 may be a polymer dispersed liquid crystal, and the second liquid crystal layer BP2 may be a liquid crystal layer with twisted liquid crystal alignment.

  For example, in the first embodiment, the blue phase liquid crystal layer stabilized with a polymer is prepared by adding a monomer to the mixed liquid crystal, but a template is formed using a polymer or the like to form a liquid crystal compound. Alternatively, a mixed liquid crystal composed of a chiral agent may be poured into a mold. The polymer used as a template is, for example, a material that physically adsorbs a specific molecule and may selectively adsorb a specific chiral agent. A first liquid crystal layer BP1 and a second liquid crystal layer BP2 that are phase-separated may be formed by bonding two molds into which mixed liquid crystals have been poured, or a mold is formed in the bonded substrate Then, a liquid crystal layer may be formed by pouring mixed liquid crystal. The means for forming the polymer chain is not limited to these methods, and a block copolymer in which the lattice size can be freely set may be formed.

  In each of the above embodiments, the transmission axes of the polarizing plates PL1 and PL2 which are linear polarizing plates are arranged in crossed Nicols, but may be arranged so as to be shifted from orthogonal. Further, the directions of the transmission axes of the polarizing plates PL1 and PL2 may be adjusted according to the optical rotation exhibited by the first liquid crystal layer BP1 and the second liquid crystal layer BP2.

  In each of the above embodiments, the polarizing plate PL1 and the polarizing plate PL2 are linear polarizing plates, but these may be circular polarizing plates. A circularly polarizing plate is generally a combination of a quarter-wave plate and a linearly polarizing plate, but as in the case of the above-described linearly polarizing plate, for example, the polarizing plate PL2 located on the viewer side. The slow axis and the transmission axis may be adjusted as appropriate. Moreover, when using a circularly-polarizing plate, you may make it use a broadband circularly-polarizing plate.

  In each of the above embodiments, since positive type liquid crystal is used, the electrode structure can effectively apply a lateral electric field, which is an electric field in the in-plane direction of the first substrate SUB1, to the first liquid crystal layer BP1. It has a structure. However, when negative type liquid crystal is used, the transmittance can be controlled by applying an electric field in the vertical direction (longitudinal direction) in the plane to the first liquid crystal layer BP1. The electrode structure in the case of using a negative type liquid crystal may have a VA mode electrode structure in a nematic liquid crystal such as a solid electrode.

  In each of the embodiments other than the tenth embodiment and the eleventh embodiment, a white light source is used as the backlight 15, but a field sequential backlight 15 that periodically emits a plurality of single-color light sources is used. It may be used. At this time, the liquid crystal display panel 11 may be driven by a field sequential drive that is generally used, except that the liquid crystal layer has the structure of the present invention.

  BP1 first liquid crystal layer, BP2 second liquid crystal layer, BP2a first sealing region, BP2b second sealing region, SUB1, SUB2, SUB3 substrate, 101, 201, 301 glass substrate, 102, 302 insulating layer, 103 , 203, 303 TFT element semiconductor layer, 104, 204, 304 insulating layer, 105, 205, 305 insulating layer, 106, 206 overcoat layer, 107, 207 black matrix, 108R, 208G color filter, PL1, PL2 polarizing plate , EFL electric field (electric field lines), TFT thin film transistor, GL scanning signal line (wiring electrode), DL video signal line, PX pixel electrode, CT1, CT2 common electrode, CL common wiring, SE seal material, 1 liquid crystal display device, 11 liquid crystal display panel, 12 video signal line drive circuit, 13 scanning line drive Dynamic circuit, 14 control circuit, 15 backlight.

Claims (10)

A first substrate and a second substrate;
A first polarizing plate disposed on the opposite side of the first substrate with respect to the second substrate;
A second polarizing plate disposed on the opposite side of the second substrate with respect to the first substrate;
A first liquid crystal layer disposed between the first substrate and the second substrate and encapsulating a blue phase liquid crystal;
A second liquid crystal layer disposed between the first substrate and the second substrate and closer to the second substrate than the first liquid crystal layer;
An electrode group for applying an electric field having an in-plane direction component of the first substrate to the first liquid crystal layer;
The second liquid crystal layer exhibits optical rotation in the opposite direction to the optical rotation exhibited by the first liquid crystal layer;
A liquid crystal display device characterized by the above. The liquid crystal display device according to claim 1,
The first liquid crystal layer has a Bragg diffraction wavelength of 380 nm or less.
A liquid crystal display device characterized by the above. The liquid crystal display device according to claim 1,
Blue phase liquid crystal is sealed in the second liquid crystal layer.
A liquid crystal display device characterized by the above. The liquid crystal display device according to claim 1,
In the second liquid crystal layer, a liquid crystal exhibiting a chiral nematic phase is sealed.
A liquid crystal display device characterized by the above. The liquid crystal display device according to any one of claims 1 to 4,
The liquid crystal display device further includes a third substrate between the first substrate and the second substrate,
The first liquid crystal layer is disposed between the first substrate and the third substrate, and the second liquid crystal layer is disposed between the second substrate and the third substrate.
A liquid crystal display device characterized by the above. The liquid crystal display device according to any one of claims 1 to 4,
The first liquid crystal layer and the second liquid crystal layer are disposed to have an interface in contact with each other;
A liquid crystal display device characterized by the above. The liquid crystal display device according to any one of claims 1 to 4,
The first liquid crystal layer and the second liquid crystal layer are arranged separated from each other by a separation film;
A liquid crystal display device characterized by the above. The liquid crystal display device according to claim 3,
The second liquid crystal layer includes
Including a first liquid crystal material and a second liquid crystal material exhibiting a blue phase and having different Bragg diffraction wavelengths in the visible wavelength region, wherein the first liquid crystal material and the second liquid crystal material are formed on the second substrate. Divided into parallel directions,
A liquid crystal display device characterized by the above. The liquid crystal display device according to any one of claims 1 to 8,
The electrode group includes a first electrode and a second electrode,
At least the first electrode is an electrode formed in a comb shape,
An electric field having an in-plane direction component of the first substrate is applied to the first liquid crystal layer by the first electrode and the second electrode.
A liquid crystal display device characterized by the above. The liquid crystal display device according to any one of claims 1 to 9,
The liquid crystal display device
A backlight disposed on the opposite side of the first substrate with respect to the first liquid crystal layer;
A color filter disposed on the opposite side of the second substrate with respect to the second liquid crystal layer,
A liquid crystal display device characterized by the above.

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