JP5203322B2 - Projection type liquid crystal display device - Google Patents

Description

  The present invention relates to a projection liquid crystal display device including a reflective liquid crystal panel using a blue phase.

  Patent Document 1 discloses a reflective liquid crystal display device that uses a nematic liquid crystal or a cholesteric liquid crystal and performs display by changing the reflectance of a pixel by controlling the orientation of the liquid crystal by an electric field. The reflection type liquid crystal panel included in such a reflection type liquid crystal display device is used not only for small and medium size liquid crystal display devices such as mobile phones but also for projection type liquid crystal display devices such as projectors.

  In a projection type liquid crystal display device, in addition to using a reflection type liquid crystal panel, a method using a transmission type liquid crystal panel or a digital light processing (DLP) method is also known. Compared to the DLP system, which turns on and off the display in several tens to several hundreds of microseconds by mechanically driving the light source and reflector, the reflective and transmissive liquid crystal panels have a liquid crystal display that is turned on and off. Since the response time is about several ms to several tens of ms, the moving image quality is poor. With regard to this, it is thought that the moving image quality can be improved by reducing the response time, but the response time of the liquid crystal depends on the viscosity and elastic constant, which are the properties of the liquid crystal material, so that other liquid crystal properties are not deteriorated. It is considered difficult to improve the response speed.

  Here, in Patent Document 2, a low-molecular liquid crystal capable of developing a blue phase between a cholesteric phase and an isotropic phase, and a non-liquid crystalline monomer that is a polymer network formed in the low-molecular liquid crystal. A liquid crystal material composed of a blue phase of a composite liquid crystal composition comprising a polymer network formed by polymerization with a crosslinking agent is disclosed. When such a liquid crystal material is used, the response speed is improved as compared with the nematic liquid crystal.

  Patent Document 3 uses a polymer-stabilized blue phase composed of a low-molecular liquid crystal capable of developing a blue phase between a cholesteric phase and an isotropic phase, and a polymer network formed in the low-molecular liquid crystal. A liquid crystal display device has been disclosed. In the liquid crystal display element disclosed in Patent Document 3, by applying an electric field in the in-plane direction to the cell substrate, a large change in birefringence is exhibited, and the light transmittance is controlled.

  Note that the blue phase and the above-described polymer-stabilized blue phase are a kind of photonic crystals having a three-dimensional lattice structure. The lattice is composed of a cylinder and a disclination having a double helix structure composed of liquid crystal molecules, and in the polymer-stabilized blue phase, a polymer network is formed in this disclination.

Japanese Patent Laid-Open No. 10-206882 JP 2003-327966 A International Publication WO2005 / 090520

  Here, the response time is improved by using a blue phase of a high-speed response for the projection-type liquid crystal display device having a reflective liquid crystal panel.

  In addition, Bragg reflection is used for reflective display using blue phase liquid crystal, but there are cases where two or more reflection peak wavelengths reflected by Bragg on different crystal planes appear in the visible wavelength region.

  Therefore, the present invention provides a projection type liquid crystal display device using a liquid crystal panel sandwiching blue phase liquid crystal having two or more reflection peak wavelengths in the visible wavelength region and improving the liquid crystal response and reducing the number of components. The purpose is to do.

  In view of the above-described object, the present invention provides a liquid crystal panel having a liquid crystal layer that exhibits optical isotropy when no voltage is applied and exhibits optical anisotropy when a voltage is applied to change the reflectance, and a light beam applied to the liquid crystal panel. A light source that supplies light, and reflects the light from the light source by the liquid crystal panel and projects the image by reflecting the light, and the liquid crystal layer has a voltage applied when a voltage is applied. The first reflection peak wavelength and the second reflection peak wavelength are shown in the visible wavelength region, and the light source includes a first light source spectrum corresponding to the first reflection peak wavelength and a second light source corresponding to the second reflection peak wavelength. The spectrum is supplied to the liquid crystal panel independently of each other.

  In one aspect of the projection type liquid crystal display device according to the present invention, the liquid crystal layer showing the first reflection peak wavelength and the second reflection peak wavelength is a first liquid crystal layer, and the first liquid crystal layer is included. The liquid crystal panel is a first liquid crystal panel, and a second liquid crystal having a third reflection peak wavelength different from the first reflection peak wavelength and the second reflection peak wavelength in at least the visible wavelength region when a voltage is applied. A second liquid crystal panel having a layer is disposed at a position different from that of the first liquid crystal panel, and the light source periodically divides the first light source spectrum and the second light source spectrum at timings different from each other. In addition to being supplied to the liquid crystal panel, a third light source spectrum corresponding to the third reflection peak wavelength is supplied to the second liquid crystal panel, and the second liquid crystal panel includes the first light source spectrum. Le and the second light source spectrum, the third light source spectrum is supplied are separated, it may be characterized in that.

  In one aspect of the projection type liquid crystal display device according to the present invention, the liquid crystal panel has the liquid crystal layer showing the first reflection peak wavelength and the second reflection peak wavelength as the first liquid crystal layer, and the voltage is A second liquid crystal layer that exhibits at least a third reflection peak wavelength different from the first reflection peak wavelength and the second reflection peak wavelength in the visible wavelength region when applied, and a pair of substrates, The first liquid crystal layer and the second liquid crystal layer are sandwiched between the pair of substrates and separated and sealed by a sealing material provided between the pair of substrates, and the light source includes the first liquid crystal layer A light source spectrum, a second light source spectrum, and a third light source spectrum corresponding to the third reflection peak wavelength are supplied to the liquid crystal panel, and at least the first light source spectrum and the second light source spectrum are supplied. The source spectrum is periodically supplied to the liquid crystal panel at different timings, it may be characterized in that.

  In one aspect of the projection type liquid crystal display device according to the present invention, the liquid crystal panel has the liquid crystal layer showing the first reflection peak wavelength and the second reflection peak wavelength as the first liquid crystal layer, and the voltage is A second liquid crystal layer showing at least a third reflection peak wavelength different from the first reflection peak wavelength and the second reflection peak wavelength in the visible wavelength region when applied, and three substrates; The first liquid crystal layer is sandwiched between two of the three substrates, and the second liquid crystal layer includes one of the two substrates and the three substrates. The light source is sandwiched between layers different from the first liquid crystal layer by one substrate other than the two substrates, and the light source includes the first light source spectrum, the second light source spectrum, and the The third light source spectrum corresponding to the third reflection peak wavelength is Supplies to the liquid crystal panel, wherein at least the first light source spectrum second source spectrum is periodically supplied to the liquid crystal panel at different timings, may be characterized in that.

  In one aspect of the projection type liquid crystal display device according to the present invention, when the first liquid crystal layer is sandwiched on the light incident side of the liquid crystal panel with respect to the second liquid crystal layer, the light source is The third light source spectrum is supplied to the liquid crystal panel so that the amount of light of the third light source spectrum is larger than that of the first light source spectrum and the second light source spectrum, and the second liquid crystal layer is compared with the first liquid crystal layer. The light source is supplied to the liquid crystal panel so that the amount of light of the first light source spectrum or the second light source spectrum is larger than that of the third light source spectrum. It may be a feature.

  In one aspect of the projection type liquid crystal display device according to the present invention, in the visible wavelength region, a region of 400 nm or more and less than 500 nm is a blue visible wavelength region, a region of 500 nm or more and 600 nm or less is a green visible wavelength region, and less than 600 nm is 700 nm or less. The first reflection peak wavelength, the second reflection peak wavelength, and the third reflection peak wavelength are visible wavelengths of different colors from the blue, green, and red visible wavelength regions. It may be characterized by existing in a region.

  In the projection type liquid crystal display device according to the aspect of the invention, the liquid crystal layer may include a blue phase liquid crystal.

  In one aspect of the projection type liquid crystal display device according to the present invention, the blue phase liquid crystal may be stabilized by being networked with a polymer.

  Further, in one aspect of the projection type liquid crystal display device according to the present invention, the liquid crystal panel has a pair of substrates that sandwich the liquid crystal layer, and a light incident side substrate of the pair of substrates has a circular shape. A polarizing plate may be provided.

  In one aspect of the projection type liquid crystal display device according to the present invention, the liquid crystal panel includes a pair of substrates that sandwich the liquid crystal layer, and the light incident side substrate of the pair of substrates is transparent. The substrate may include an electrode formed in a comb shape, and a lateral electric field may be applied to the liquid crystal layer by applying a voltage to the electrode.

  In the projection type liquid crystal display device according to the aspect of the invention, the first liquid crystal layer and the second liquid crystal layer may include a blue phase liquid crystal that appears in a common temperature range.

  As described above, according to the present invention, a projection type liquid crystal display using a liquid crystal panel sandwiching a blue phase liquid crystal that exhibits two or more reflection peak wavelengths while reducing the number of components while improving the response of the liquid crystal. Equipment can be provided.

It is a figure explaining the outline of the structure of one pixel of the reflection type liquid crystal panel in the projection type liquid crystal display device which concerns on one Embodiment of this invention, and the state of the light in voltage ON-OFF. It is a figure explaining the method of selectively taking out reflected light from the blue phase liquid crystal which has two reflection peaks. It is a figure for demonstrating the display method in the case of carrying out full color display of the projection type liquid crystal display device which concerns on one Embodiment of this invention. It is a figure for demonstrating the other example of the display method in the case of carrying out full color display of the projection type liquid crystal display device which concerns on one Embodiment of this invention. 1 is a basic configuration diagram of a color separation / synthesis system that is a main part of a projection-type liquid crystal display device according to a first embodiment of the present invention; 1 is a schematic cross-sectional view including a thin film transistor of one pixel in a reflective liquid crystal panel according to an embodiment of the present invention. 1 shows a schematic diagram of a structure of one pixel of a reflective liquid crystal panel according to a first embodiment of the present invention. 1 shows a schematic diagram of a structure of one pixel of a reflective liquid crystal panel according to a first embodiment of the present invention. 1 is a basic configuration diagram of a color separation / synthesis system that is a main part of a projection type liquid crystal display device according to an embodiment of the present invention; FIG. FIG. 5 shows a schematic diagram of a pixel structure in a reflective liquid crystal panel according to a second embodiment of the present invention. It is the schematic of the pixel structure in the reflection type liquid crystal panel concerning the 3rd Example of this invention.

  Hereinafter, embodiments and examples of the projection type liquid crystal display device according to the present invention will be described. It goes without saying that the present invention can be appropriately modified within the scope of the technical idea disclosed in the present specification including the following embodiments and examples.

  First, the principle of operation of the projection type liquid crystal display device according to the present embodiment will be described with reference to FIGS. First, FIG. 1 is a diagram for explaining a pixel structure of a reflective liquid crystal panel in a projection type liquid crystal display device according to the present embodiment and a light state at a voltage ON-OFF. FIG. 1 schematically shows the structure of one pixel in a reflective liquid crystal panel.

  As shown in FIG. 1, in a reflective liquid crystal panel, a liquid crystal layer 104 including a blue phase liquid crystal is sandwiched between a substrate 101 and a substrate 102 that are transparent at least on the light incident side. The substrate 101 has comb-shaped electrodes, and the liquid crystal layer 104 is a blue phase liquid crystal having two independent reflection peaks in the visible wavelength region, or a blue phase having one reflection peak in the visible wavelength region. Phase liquid crystal. Here, the visible wavelength region means a region having a wavelength of 360 nm to 830 nm in this specification. The blue phase liquid crystal exhibits optical isotropy when no voltage is applied, and exhibits optical anisotropy when a voltage is applied.

  Further, when inducing birefringence in the liquid crystal layer 104, the substrate 101 and the substrate 102 are arranged so that the phase difference when the electric field is applied is λ / 4 with a sufficient distance between the substrates. Further, a retardation plate (λ / 4 plate) 106 and a polarizing plate 105 are disposed on the opposite side of the liquid crystal layer 104 in the substrate 101 to form a circularly polarizing plate. In the reflective liquid crystal panel according to this embodiment, the substrate 101 on the light incident side has a circularly polarizing plate, and at least the substrate 101 on the light incident side uses a transparent substrate on which comb-shaped electrodes are arranged. The pixel structure includes a liquid crystal layer 104 including a phase liquid crystal, but is not limited to this structure.

  The circularly polarizing plate may be disposed away from the liquid crystal panel sandwiching the blue phase liquid crystal, or on the light incident side substrate 101 opposite to the side where the blue phase liquid crystal is sandwiched or the blue phase liquid crystal. May be arranged on either side of the pin. In order to increase the color purity of the reflective liquid crystal panel, a color filter may be formed, or an alignment film may be formed on the substrate 101 or the substrate 102 in order to align the lattice plane of the blue phase liquid crystal. .

  Next, the operation principle of each pixel of the reflective liquid crystal panel sandwiching the blue phase liquid crystal will be described by taking the case of using the left circularly polarizing plate as an example. As shown in FIG. 1, when linearly polarized light enters through the polarizing plate 105 from above in the drawing, left-handed circularly polarized light is obtained by the phase difference plate (λ / 4 plate) 106. That is, by using the left circularly polarizing plate, light incident on the liquid crystal layer 104 becomes left circularly polarized light. The liquid crystal layer 104 is optically isotropic when no voltage is applied, and the incident left circularly polarized light is reflected by the lattice plane of the blue phase liquid crystal. The reflected light becomes right circularly polarized light, and when it passes through the phase difference plate (λ / 4 plate) 106 again, it becomes linearly polarized light orthogonal to the original linearly polarized light, and therefore cannot pass through the polarizing plate 105. On the other hand, the liquid crystal layer 104 exhibits optical anisotropy when a voltage is applied. Although the transmittance changes according to the voltage, the maximum transmittance is indicated by the fact that the left circularly polarized light incident on the liquid crystal layer 104 is converted into elliptically polarized light, reflected by the lattice plane in the blue phase liquid crystal, and then again the liquid crystal When passing through the layer 104 and the phase difference plate (λ / 4 plate) 106, the phase difference becomes linearly polarized light with a shift of 360 °, so that it can pass through the polarizing plate. Further, when the right circularly polarizing plate is used, although the light incident on the liquid crystal layer 104 becomes right circularly polarized light, the operation principle is the same as described above. As described above, it is possible to control the extraction of reflected light from the liquid crystal panel as needed by including the circularly polarizing plate and changing the optical properties by turning the voltage on the liquid crystal layer 104 on and off.

Next, FIG. 2 is a diagram for explaining a method of selectively extracting reflected light from a blue phase liquid crystal having two reflection peaks. By using this figure, the reflection of λ ₁ or λ ₂ from a blue phase liquid crystal pixel having a first reflection peak wavelength λ ₁ and a second reflection peak wavelength λ ₂ which are two independent reflection peaks in the visible wavelength region. A method for individually extracting light will be described. ₂ will be described based on a liquid crystal panel using a blue phase liquid crystal having reflection peak wavelengths λ ₁ and λ ₂ in the liquid crystal layer 104 shown in FIG. The liquid crystal layer 104 exhibits optical isotropy when no voltage is applied, and exhibits optical anisotropy when a voltage is applied. Based on the above principle, light incident upon voltage application passes through the circularly polarizing plate due to induced birefringence. However, when white light is used as the light source, both λ ₁ and λ ₂ are reflected and passed, and thus are extracted independently. I can't. In order to individually extract the light corresponding to the two reflection peaks, the first light source spectrum corresponding to the first reflection peak wavelength λ ₁ and the second light source spectrum corresponding to the second reflection peak wavelength λ ₂ are respectively independent. To be incident on the liquid crystal panel. Therefore, a light source that can supply the first light source spectrum Λ ₁ and the second light source spectrum Λ ₂ to the liquid crystal panel independently of each other is used as the light source. As shown in FIG. 2, when the light of λ ₁ is extracted, the first light source spectrum Λ ₁ of the light source is turned on and a voltage is applied to the pixel of the liquid crystal panel. The light of the first light source spectrum Λ ₁ incident on the liquid crystal panel can be reflected by the lattice plane of the liquid crystal layer 104 in which birefringence is induced and pass through the polarizing plate. Similarly, when extracting light having the second reflection peak wavelength λ ₂ , the second light source spectrum Λ ₂ of the light source is turned on, and a voltage is applied to the pixel of the liquid crystal panel. When both the first reflection peak wavelength λ ₁ and the second reflection peak wavelength λ ₂ are extracted, the first light source spectrum Λ ₁ and the second light source spectrum Λ _{2 of} the light source are turned on. When a voltage is applied to the pixels of the liquid crystal panel, the light having the first reflection peak wavelength λ ₁ and the second reflection peak wavelength λ ₂ is reflected by the lattice plane of the liquid crystal layer 104 in which birefringence is induced and passes through the polarizing plate. . Furthermore, regardless of whether the light source is on or off, the liquid crystal layer 104 exhibits optical isotropy when no voltage is applied to the pixel. Therefore, although incident light is reflected by the lattice plane of the liquid crystal layer 104, a circularly polarizing plate The light cannot be extracted because it cannot pass through. However, in order to prevent light leakage due to light reflection at the interface, the light source is preferably OFF. The first light source spectrum Λ ₁ corresponding to the first reflection peak wavelength λ ₁ in the present embodiment refers to a wavelength distribution having an intensity around it including at least the first reflection peak wavelength λ ₁ . It is desirable that the first light source spectrum Λ ₁ has a distribution in which the peak intensity substantially coincides with the first reflection peak wavelength λ ₁ and the intensity decreases with increasing distance from the wavelength that is the peak intensity. The same applies to the second light source spectrum lambda _2.

  By the above method, it is possible to take out one reflected light from a pixel of a liquid crystal panel using a blue phase liquid crystal having two or more reflection peaks.

From the above viewpoint, a case where a projection liquid crystal display device using a reflective liquid crystal panel performs full color display will be described. In this case, for example, the first reflection peak wavelength λ ₁ in the blue visible wavelength region (400 nm or more and less than 500 nm) and the second reflection peak wavelength λ ₂ in the red visible wavelength region (greater than 600 nm and 700 nm or less) A first liquid crystal panel having a liquid crystal layer 104A made of a blue phase liquid crystal and a liquid crystal layer 104B made of a blue phase liquid crystal having a third reflection peak wavelength λ ₃ in the green visible wavelength region (500 nm to 600 nm). Two liquid crystal panels may be arranged at different positions and voltage controlled independently. The light source includes a first light source spectrum lambda ₁ having no distribution in the red visible wavelength region is mainly distributed in the blue visible wavelength region, the third light source spectrum lambda ₃ distributed primarily in green visible wavelength region And the second light source spectrum Λ ₂ that is mainly distributed in the red visible wavelength region and has no distribution in the blue visible wavelength region is controlled to be supplied independently. In the present specification and drawings, when the terms red, green, and blue are used without particular notice, they correspond to the above visible wavelength band.

FIG. 3 is a diagram for explaining an example of a display method in the case of performing full color display on the projection type liquid crystal display device using the first liquid crystal panel and the second liquid crystal panel. In this projection type liquid crystal display device, red, green and blue light emission are controlled to be supplied independently. Specifically, the three light emission are time-divided at different timings and periodically supplied to the liquid crystal panel. Is done. When the pixel PX1 in the first liquid crystal panel is displayed in red, the red light source is turned on and a voltage is applied to the pixel PX1. Since the liquid crystal layer 104A of the first liquid crystal panel induces birefringence, red light reflected by the lattice plane passes through the circularly polarizing plate, and red is displayed. Note that when red is incident on the second liquid crystal panel, the liquid crystal layer 104B does not include a component that reflects red, and thus passes through the liquid crystal layer 104B regardless of whether or not voltage is applied. However, it is preferable not to apply a voltage in order to prevent leakage of light reflected at the interface between the liquid crystal layer 104B and the substrate 102 of the second liquid crystal panel. Similarly, the projection type liquid crystal display device can independently display the pixel PX2 in green and the pixel PX1 in blue. Then, the pixel PX1 of the first liquid crystal panel is driven to generate an image corresponding to the supplied light source spectrum according to the timing at which the first light source spectrum Λ ₁ and the second light source spectrum Λ ₂ are supplied from the light source. The The third pixel PX2 of the second liquid crystal panel in accordance with the timing of the light source spectrum lambda ₃ is supplied are driven by image generated from these two liquid crystal panels are synthesized, the full-color image Will be displayed. Here, the liquid crystal layer 104B of the second liquid crystal panel also includes blue phase liquid crystal, but the second liquid crystal panel is, for example, a transmissive / reflective liquid crystal panel in which nematic liquid crystal is sealed. Thus, the third light source spectrum may be supplied to the second liquid crystal panel. Also in this case, the first liquid crystal panel synthesizes the image generated from the first light source spectrum and the second light source spectrum and the image generated from the third light source spectrum by the second liquid crystal panel, and produces a full color. An image will be displayed.

As described above, since light of two reflection peaks in the first liquid crystal panel can be decomposed by individually entering red and blue light into the pixel PX1, red, green, and blue are displayed independently. It becomes possible. As described above, the light source emits light so that the first light source spectrum Λ ₁ , the third light source spectrum Λ ₃ , and the second light source spectrum Λ ₂ are independently supplied to the liquid crystal panel. Since the presence of the three light source spectrum Λ ₃ has little influence on the display of the pixel PX1, it may be caused to emit light simultaneously depending on the first light source spectrum Λ ₁ or the second light source spectrum Λ ₂ , and at least the first light source spectrum. It is only necessary that Λ ₁ and the second light source spectrum Λ ₂ are supplied to the liquid crystal panel independently of each other.

FIG. 4 is a diagram for explaining another example of the display method in the case of performing full color display on the projection type liquid crystal display device using the first liquid crystal panel and the second liquid crystal panel arranged at different positions. In FIG. 4, the green-blue emission having the first light source spectrum Λ ₁ and the third light source spectrum Λ ₃ is different from the red-green emission having the second light source spectrum Λ ₂ and the third light source spectrum Λ _3. It starts at the timing and emits light alternately. In the projection type liquid crystal display device, when displaying red, the red and green light sources are turned on and a voltage is applied to the pixel PX1. The red-green light incident on the pixel PX1 is reflected only by the red light on the lattice plane of the liquid crystal layer 104A in which birefringence is induced, and passes through the circularly polarizing plate. The same can be done when displaying blue. In the case of displaying green, a voltage is applied to the pixel PX2, and the light source is turned on for both red-green light emission and green-blue light emission, but when the light source is at least one of red-green and green-blue light ON. Can be displayed. That is, the light source does not periodically repeat red, green, and blue light emission at different timings, but red-green light emission and green-blue light emission, red light emission and green-blue light emission, or red-green light emission and blue light emission. It is also possible to control so that the two light emissions in are repeated alternately.

Note that the blue phase liquid crystal included in the liquid crystal layer 104 according to the present embodiment has a lattice size of about the visible light wavelength, and has a reflection peak wavelength due to Bragg reflection in the visible wavelength region. Therefore, when the reflection of the blue phase liquid crystal is visually observed, it is colored by the reflected light derived from the Bragg reflection depending on the orientation of the crystal with respect to the incident light. The case where two reflection peak wavelengths exist in the visible wavelength region occurs because the reflection peak wavelength is λ _hkl = 2nd / (h ² + k ² + l ² ) ^{1 /} using the lattice constant d and 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.

  In the projection type liquid crystal display device according to the present embodiment, the first light source spectrum and the second light source spectrum are independently supplied to the reflective liquid crystal panel having the first reflection peak wavelength and the second reflection peak wavelength. Therefore, in the light source, there may be a case where the control of the light emission of the first light source spectrum and the light emission of the second light source spectrum is independently supplied to the liquid crystal panel and temporarily displays purple. Further, in the light source, even if the light emission period of the first light source spectrum and the light emission period of the second light source spectrum are periodically supplied at different timings, the colors are temporally mixed and purple is displayed. Good.

In the description of the above embodiment and the following examples, the first reflection peak wavelength λ ₁ exists in the blue visible wavelength region, the second reflection peak wavelength λ ₂ exists in the red visible wavelength region, The third reflection peak wavelength λ ₃ is present in the green visible wavelength region. For example, the first reflection peak wavelength is present in the green visible wavelength region and the second reflection peak wavelength is present in the red visible wavelength region. The blue layer liquid crystal may be prepared so that the wavelength exists in the blue visible wavelength region. In the following, the present invention will be described more specifically with reference to examples.

  First, a first embodiment of the projection type liquid crystal display device of the present invention will be described in detail with reference to the drawings.

  FIG. 5 is a basic configuration diagram of a color separation / synthesis system which is a main part of the projection type liquid crystal display device according to the present embodiment, and FIG. 6 includes a thin film transistor of one pixel in the reflection type liquid crystal panel according to the present embodiment. A schematic cross-sectional view is shown, and FIG. 7 shows a schematic diagram of the structure of one pixel of the reflective liquid crystal panel according to this embodiment.

  In this embodiment, the light emitted from the LED light source 10 which is a light source capable of independently controlling red, green and blue as shown in FIG. 3 is separated into red blue and green by the dichroic color separation filter 11. To the first liquid crystal panel L1 having a first reflection peak and a second reflection peak independent in the red and blue wavelength regions, and 1 independent in the green wavelength region via the reflector 12 and the polarization beam splitter 15, respectively. A color image is projected on the screen 13 by being reflected by the second liquid crystal panel L2 having two reflection peaks and finally recombining by the combining prism 14.

  As shown in FIG. 6, as the substrate 101 and the substrate 102 of the liquid crystal panel, two quartz substrates having high transparency in the visible region, no absorption of light at a curing wavelength of 365 nm, and a thickness of 0.7 mm are used. Use. Then, a thin film transistor 120 and a wiring electrode capable of applying a lateral electric field were formed on one of these substrates, and an insulating protective film 113 made of silicon nitride was further formed thereon to form an active matrix substrate. The thin film transistor 120 includes a pixel electrode 108, a signal electrode (drain electrode) 109, a scan electrode (gate electrode) 107, and a semiconductor film 111 made of amorphous silicon. A gate insulating film 112 is interposed between the scan electrode 107 and the semiconductor film 111. Intervene.

  A liquid crystal composed of a blue phase liquid crystal is sealed between the substrate 101 and the substrate 102. The cell gap was set to 25 μm through the spacer agent. By increasing the thickness of the liquid crystal layer 104, a phase difference independent of the cell gap can be obtained. A λ / 4 retardation plate 106 and a polarizing plate 105 are disposed on the outer surface of the glass substrate 101 constituting the active matrix substrate to form a circularly polarizing plate.

  FIG. 7 schematically shows the pixel structure of the liquid crystal panel according to this example. 7A schematically illustrates the pixel structure of the first liquid crystal panel L1, and FIG. 7B schematically illustrates the pixel structure of the second liquid crystal panel L2. In this embodiment, the liquid crystal layer 104A is a polymer-stabilized blue phase liquid crystal having one reflection peak in the red and blue visible wavelength regions, and the liquid crystal layer 104B has one reflection peak in the green visible wavelength region. A polymer-stabilized blue phase liquid crystal having Here, the blue phase liquid crystal of the liquid crystal layer 104A and the liquid crystal layer 104B includes JC1041-XX (manufactured by Chisso Corp.), 4-pentyl-4′-cyanobiphenyl (5CB) (manufactured by Aldrich Corp.), and ZLI-4572 (manufactured by Aldrich Corp.). (Merck) was used after being heated and mixed. The ratio of mixing three materials by heating (JC1041-XX / 4-pentyl-4′-cyanobiphenyl (5CB) / ZLI-4572 (mol%)) is 48.0 / 48.0 / 4.4 in the liquid crystal layer 104A. 0 (mol%) and 47.6 / 47.6 / 4.8 (mol%) in the liquid crystal layer 104B. Furthermore, 2-ethylhexyl acrylate (EHA) (manufactured by Aldrich) and RM257 (manufactured by Merck) as monomers were added to the mixed liquid crystal. The monomer composition ratio (2-ethylhexyl acrylate (EHA) / RM257 (mol%)) is 70/30 (mol%). Further, 2,2-dimethylphenylacetophenone (DMPAP) (manufactured by Aldrich) is used as a photopolymerization initiator. The monomer content in the mixed solution was 6.3 (mol%), and DMPAP was adjusted to 10 (wt%) with respect to the mixed monomer. By producing blue phase liquid crystals by changing the concentration of blue, it is possible to produce blue phase liquid crystals having different wavelengths exhibiting reflection peaks.

The mixed liquid crystal was vacuum injected into the first liquid crystal panel L1 and the second liquid crystal panel L2 in an isotropic phase state. The temperature of the panel is kept constant in the temperature range where the mixed liquid crystal develops BPI, the ultraviolet light having an irradiation intensity of 1.8 mWcm ⁻² (365 nm) is irradiated, and a polymer chain is formed, so that the onset temperature of the blue phase liquid crystal A wide range of polymer stabilized blue phases were prepared.

  The liquid crystal layer 104A has a first reflection peak wavelength of 460 nm and a second reflection peak wavelength of 650 nm, and is a polymer-stabilized blue phase that reflects two wavelengths of blue and red. The liquid crystal layer 104B has a third reflection peak. It consists of a polymer-stabilized blue phase liquid crystal having a peak wavelength at 550 nm and reflecting a green wavelength.

  As described above, an active matrix type first liquid crystal panel L1 and second liquid crystal panel L2 using TFTs are configured. Here, the liquid crystal layers 104A and 104B show an isotropic phase having a double spiral structure when the voltage of the gate electrode is not applied and the TFT is off, but when the voltage is applied and the TFT is turned on. An electric field is applied to the liquid crystal layers 104A and 104B due to a potential difference between the pixel electrode and the common electrode, and refractive index anisotropy is induced.

  A display method of the projection type liquid crystal display device according to the present embodiment will be described with reference to FIG. When displaying red, the LED light source 10 applies a voltage to the necessary pixels of the first liquid crystal panel according to the timing of emitting the red second light source spectrum. The red light emitted from the LED light source 10 is reflected by the dichroic color separation filter 11, the reflection plate 12, and the polarization beam splitter 15, and enters the first liquid crystal panel L 1. The red light reaching the liquid crystal layer 104 is reflected by the lattice plane of the liquid crystal layer 104 and passes through the circularly polarizing plate in the pixel to which the voltage is applied, so that a red image is displayed by the first liquid crystal panel L1. The Rukoto. Tables 1 and 2 show light source control methods for displaying red, green, blue, and representative colors.

  The notation of ON or OFF in the pixels PX1 and PX2 in Tables 1 and 2 above indicates whether or not voltage is applied. A voltage is applied when ON, and no voltage is applied when OFF. The notation of ON or OFF in red, blue, and green indicates whether or not each color is supplied by the light source. When displaying an image composed of mixed colors of red, green and blue, the image by the first liquid crystal panel and the image by the second liquid crystal panel are combined by the combining prism 14. With the configuration as described above, a projection type liquid crystal display device capable of good full color display using a polymer stabilized blue phase liquid crystal can be obtained.

  Below, the 2nd Example of the liquid crystal display device of this invention is explained in full detail based on drawing.

  FIG. 8 is a basic configuration diagram of a color separation / synthesis system that is a main part of the projection type liquid crystal display device according to the second embodiment, and the electrode structure and active element structure in the vicinity of one pixel are the same as those in the first embodiment. It has the structure shown in FIG. FIG. 9 shows a schematic diagram of a pixel structure in the reflective liquid crystal panel L3 according to the second embodiment, in which a thin film transistor (TFT) is omitted.

  As shown in FIG. 8, in this embodiment, the light emitted from the LED light source 10 which is a light source capable of independently controlling red, green, and blue is reflected to the liquid crystal panel L3 via the polarization beam splitter 15. The color image is projected onto the screen 13.

  As shown in FIG. 9, the liquid crystal panel according to the second embodiment includes a pixel PX1 and a pixel PX2 via a seal material SE. The pixel PX1 has a liquid crystal layer 104A composed of a polymer-stabilized blue phase liquid crystal having one independent reflection peak in the red / blue wavelength region, and the pixel PX2 has an independent reflection in the green wavelength region. A liquid crystal layer 104B made of polymer-stabilized blue phase liquid crystal having one peak is sandwiched. The pixel structures of the pixel PX1 and the pixel PX2 have the same structure as the pixel structure in the liquid crystal panel in the first embodiment.

  In the liquid crystal layer 104A sandwiched between the pixels PX1, JC1041-XX and 5CB as liquid crystals and ZLI-4572 as a chiral agent were mixed by heating. Each ratio (JC1041-XX / 5CB / ZLI-4572 (mol%)) was 48.0 / 48.0 / 4 (mol%). Further, the liquid crystal layer 104B sandwiched between the pixels PX2 was heated and mixed with JC1041-XX and 5CB as liquid crystals and BDH1281 (Merck) as a chiral agent. Each ratio (JC1041-XX / 5CB / BDH1281 (mol%)) was 48.5 / 48.5 / 3.0 (mol%). In the mixed liquid crystal, EHA and RM257 were added as monomers. The monomer composition ratio (EHA / RM257 (mol%)) is 70/30 (mol%). Furthermore, DMPAP was added to the photopolymerization initiator to obtain a uniform 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.

The mixed liquid crystal was vacuum injected into the panel in an isotropic phase. When using the same chiral reagent, T _C of the chiral agent is for less than the liquid crystal of T _NI, according to the concentration of the chiral agent in the mixed crystal is increased, tends to decrease the temperature range expressing BPI. Accordingly, by using different chiral agent of T _C, aligned expression temperature i.e. the curing temperature of the blue phase in the same plane which is formed in the pixel PX1 and the pixel PX2. Both the mixed liquid crystals of the pixels PX1 and PX2 were kept constant in a temperature range where BPI was developed, and a polymer-stabilized blue phase was formed by irradiating ultraviolet light with an irradiation intensity of 1.5 mWcm ⁻² (365 nm).

  The pixel PX1 has reflection peaks at 460 nm and 650 nm, has a polymer-stabilized blue phase liquid crystal that reflects two wavelengths of red and blue in the liquid crystal layer 104A, and the pixel PX2 has a reflection peak at 550 nm and is green The liquid crystal layer 104B has a polymer-stabilized blue phase liquid crystal that reflects the wavelength of.

  Each color can be displayed in the same manner as in Tables 1 and 2. For example, when displaying red, the LED light source 10 is made to light red, and a voltage is applied to a necessary pixel of the liquid crystal panel L3. The red light emitted from the LED light source 10 enters the liquid crystal panel L3. The red light is reflected by the lattice plane of the liquid crystal layer 104A and can pass through the circularly polarizing plate in the pixel to which voltage is applied to display red. With the above configuration, a projection type liquid crystal display device having a reflection type liquid crystal panel capable of good full color display was obtained.

  Hereinafter, a third embodiment of the projection type liquid crystal display device according to the present invention will be described in detail with reference to the drawings.

  FIG. 10 is a schematic diagram of a pixel structure in a reflective liquid crystal panel according to the third embodiment. The color separation / synthesis system, which is the main part of the projection type liquid crystal display device in this embodiment, is similar to the projection type liquid crystal display device according to the second embodiment, and is shown in FIG. The reflective liquid crystal panel L3 according to the third embodiment has the same electrode structure and active element structure in the vicinity of one pixel as in FIG. In FIG. 10, a thin film transistor (TFT) is omitted.

  As shown in FIG. 10, the reflective liquid crystal panel according to the third embodiment has three substrates 101, 102, 103, and shows a blue phase exhibiting a first reflection peak wavelength and a second reflection peak wavelength. A liquid crystal layer 104A containing liquid crystal is sandwiched between the substrates 101 and 102, and a liquid crystal layer 104B containing blue phase liquid crystal having a third reflection peak wavelength is sandwiched between the substrates 102 and 103. Further, as shown in the figure, a pixel electrode 108 and a common electrode 110 both having a comb-like shape are formed on the substrate 101 and the substrate 102. When a voltage is applied between the pixel electrode 108 and the common electrode 110, a lateral electric field is applied to the liquid crystal layer, and the reflectance is controlled.

  In this embodiment, since the liquid crystal layer 104A and the liquid crystal layer 104B are sealed in different layers and overlap each other, the pixel PX1 that reflects red and blue and the pixel PX2 that reflects green overlap, A pixel which is a minimum unit constituting a digital image to be displayed is configured. Control of the light source and the pixels when displaying red, green, blue, and representative colors can be performed in the same manner as in Tables 1 and 2. By projecting the image reflected by the liquid crystal panel L3 onto the screen 13 via the polarizing beam splitter 15, a projection type liquid crystal display device capable of good full color display can be obtained.

  The fourth embodiment of the projection type liquid crystal display device according to the present invention will be described below in detail with reference to the drawings.

  The main part and the pixel structure of the projection type liquid crystal display device according to the fourth embodiment are the same as those of the third embodiment, and the light source is an LED light source 10 capable of emitting light of two wavelength bands at different timings. Is used. The LED light source 10 includes an LED light source that uses gallium phosphide that emits light in the red to green wavelength band, and an LED that uses zinc selenide that emits light in the green to blue wavelength band as a material. Two light sources of light sources are included, and these periodically emit light at different timings. Accordingly, the wavelength band emitted by the LED light source using zinc selenide as the material includes the first light source spectrum corresponding to the first reflection peak wavelength and the third light source spectrum corresponding to the third reflection peak wavelength. . The wavelength band emitted by the LED light source using gallium phosphide as a material includes a second light source spectrum corresponding to the second reflection peak wavelength and a third light source spectrum corresponding to the third reflection peak wavelength.

  Tables 3 and 4 are diagrams illustrating a light source and pixel control method when displaying red, green, blue, and representative colors.

  Here, when displaying green, both the LED light source using gallium phosphide and the LED light source using zinc selenide are turned ON. That is, light in the wavelength band of red to green (indicated as red-green in FIG. 12) and light in the wavelength band of green to blue (indicated in green and blue in FIG. 12) are supplied to the liquid crystal layers 104A and 104B. Is supplied to the liquid crystal panel L3, which overlaps with each other, the amount of light extracted from the lower liquid crystal layer 104B, that is, the pixel PX2 apparently increases with respect to the light incident direction. The apparent amount of light lost can be recovered. Therefore, when the liquid crystal layer 104A and the liquid crystal layer 104B overlap, the amount of light corresponding to the reflection peak of the liquid crystal layer disposed in the lower layer may be increased. With the configuration as described above, a projection type liquid crystal display device capable of good full color display was obtained.

[Comparative Example 1]
The basic structure of the color separation / synthesis system, which is the main part of the projection-type liquid crystal display device, and the schematic cross-sectional view and pixel structure in the vicinity of one pixel are the same as in the second embodiment using the structure shown in FIGS. Thus, white light is used as the LED light source 10, and light sources of red spectrum, green spectrum, and blue spectrum are always supplied to the liquid crystal panel L3 at the same timing. Here, when white light is applied to the pixel PX1 in the voltage ON state, both red and blue light are reflected on the pixel PX1, and thus red and blue cannot be displayed independently.

[Comparative Example 2]
The basic structure of the color separation / synthesis system, which is the main part of the projection-type liquid crystal display device, and the schematic cross-sectional view near one pixel, the pixel structure is the same as that of the second embodiment using the structure shown in FIG. 6, FIG. 8 and FIG. Both the chiral agents used for the pixels PX1 and PX2 are ZLI4572. When the ultraviolet light was irradiated at the blue phase expression temperature of the pixel PX1, no polymer-stabilized blue phase was formed in the pixel PX2 where the blue phase did not appear during the ultraviolet irradiation. For this reason, full-color display is possible at a temperature at which the pixel PX2 develops BPI, but it has been impossible to use a projection-type liquid crystal display device in other temperature ranges.

  101, 102, 116 Substrate, 104, 104A, 104B Liquid crystal layer, 105 Polarizing plate, 106 Phase difference plate, 107 Scanning wiring (gate electrode), 108 Pixel electrode (source electrode), 109 Signal wiring (drain electrode), 110 Common Electrode (common electrode), 111 semiconductor film, 112 gate insulating film, 113 protective insulating film, 114 organic semiconductor film, 120 thin film transistor (TFT), 10 LED light source, 11 dichroic color separation filter, 12 reflector, 13 screen, 14 synthesis Prism, 15 polarizing beam splitter, PX1 pixel 1, PX2 pixel 2, L1 first liquid crystal panel, L2 second liquid crystal panel, L3 third liquid crystal panel.

Claims (8)

A liquid crystal panel having a liquid crystal layer that exhibits optical isotropy when no voltage is applied and exhibits optical anisotropy when a voltage is applied and changes reflectance, and a light source that supplies light to the liquid crystal panel, In a projection type liquid crystal display device that displays an image by reflecting and projecting light from the light source by the liquid crystal panel,
The liquid crystal layer exhibits a first reflection peak wavelength and a second reflection peak wavelength in a visible wavelength region when a voltage is applied,
The light source supplies light emission of a first wavelength distribution corresponding to the first reflection peak wavelength and light emission of a second wavelength distribution corresponding to the second reflection peak wavelength to the liquid crystal panel independently of each other ;
The liquid crystal panel includes the liquid crystal layer showing the first reflection peak wavelength and the second reflection peak wavelength as a first liquid crystal layer, and when a voltage is applied, the first reflection peak wavelength and the second reflection peak wavelength are applied. A second liquid crystal layer having at least a third reflection peak wavelength different from the reflection peak wavelength in the visible wavelength region, and three substrates;
The first liquid crystal layer is sandwiched between two of the three substrates,
The second liquid crystal layer is different from the first liquid crystal layer by one substrate of the two substrates and one substrate other than the two substrates of the three substrates. Sandwiched between different layers,
The light source supplies light emission of the first wavelength distribution, light emission of the second wavelength distribution, and light emission of a third wavelength distribution corresponding to the third reflection peak wavelength to the liquid crystal panel, and at least the first wavelength distribution The light emission of one wavelength distribution and the light emission of the second wavelength distribution are periodically supplied to the liquid crystal panel at different timings.
A projection-type liquid crystal display device. In the projection type liquid crystal display device according to claim 1 ,
When the first liquid crystal layer is sandwiched on the light incident side of the liquid crystal panel with respect to the second liquid crystal layer,
The light source is supplied to the liquid crystal panel so that the amount of light emitted from the third wavelength distribution is larger than the light emitted from the first wavelength distribution and the light emitted from the second wavelength distribution ;
When the second liquid crystal layer is sandwiched on the light incident side of the liquid crystal panel with respect to the first liquid crystal layer,
The light source supplies the liquid crystal panel so that the amount of light emitted from the first wavelength distribution or light emitted from the second wavelength distribution is larger than light emitted from the third wavelength distribution ;
A projection-type liquid crystal display device. In the projection type liquid crystal display device according to claim 1 ,
In the visible wavelength region, a region of 400 nm or more and less than 500 nm is a blue visible wavelength region, a region of 500 nm or more and less than 600 nm is a green visible wavelength region, and a region of 600 nm or more and 700 nm or less is a red visible wavelength region,
The first reflection peak wavelength, the second reflection peak wavelength, and the third reflection peak wavelength are present in the visible wavelength regions of different colors among the blue, green, and red visible wavelength regions,
A projection-type liquid crystal display device. In the projection type liquid crystal display device according to claim 1,
The first liquid crystal layer and the second liquid crystal layer include blue phase liquid crystal,
A projection-type liquid crystal display device. In the projection type liquid crystal display device according to claim 4 ,
The blue phase liquid crystal is stabilized by being networked by a polymer.
A projection-type liquid crystal display device. In the projection type liquid crystal display device according to claim 1,
The substrate most a light incident side of the front Symbol three substrates, circularly polarizing plates are provided,
A projection-type liquid crystal display device. The projection type liquid crystal display device according to claim 1.
Substrate most a light incident side of the front Symbol three substrates is a substrate of transparent, an electrode formed in a comb shape,
By applying a voltage to the electrode, a lateral electric field is applied to the first liquid crystal layer or the second liquid crystal layer .
A projection-type liquid crystal display device. In the projection type liquid crystal display device according to claim 1 ,
The first liquid crystal layer and the second liquid crystal layer include a blue phase liquid crystal that appears in a common temperature range.
A projection-type liquid crystal display device.

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