JP2009116050A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a display contrast from being degraded caused by unpolarized light after wavelength conversion when the wavelength band of a backlight which is not necessary for color image display by a liquid crystal display device is wavelength-converted and used for image display. <P>SOLUTION: A polarizing layer and a color filter are stacked in order on an internal principal surface of a substrate where light transmitted through a liquid crystal layer is projected to outside the liquid crystal display device, and a wavelength converting substance is added to a thin film formed on the color filter (on the liquid crystal layer side). The axis of polarization of the polarizing layer is in the same direction as the axis of polarization of an external polarizing plate provided on an external principal surface (the principal surface on the opposite side from the liquid crystal layer) of the substrate, and unpolarized light generated by a wavelength conversion layer is cut off. The wavelength converting substance is selected out of fluorochromes which absorb light of, for example, ≤420 nm in wavelength and emit light of ≥420 nm in wavelength. Consequently, white luminance of a transmission display screen of a liquid crystal cell is improved with the wavelength-converted light and unpolarized light components are cut off by the polarizing layer and external polarizing plate, so that black luminance of the screen is held low. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transmissive liquid crystal display device capable of color display, and more particularly to a color liquid crystal display device that improves the luminance of light transmitted from a liquid crystal backlight through a liquid crystal display device and improves display quality.

  At present, wide viewing angle liquid crystal display devices such as a lateral electric field drive (IPS (In Plane Switching)) method and a vertical electric field drive (VA (Vertical Alignment)) method are widely used as monitors in transmissive liquid crystal display devices. It is also used as a television with improved characteristics.

  FIG. 1 shows a partially enlarged cross section of a transmissive liquid crystal display device. The liquid crystal display device (liquid crystal cell) includes a so-called transparent first substrate 102 and second substrate 109 made of a material such as glass or plastic, and a liquid crystal layer 105 sandwiched therebetween, and forms the liquid crystal layer 105. The liquid crystal molecules are aligned in a specific direction by the liquid crystal alignment films 104 and 106 formed on the inner main surface (the liquid crystal layer 105 side) of the respective substrates 102 and 109. A polarizing plate (external polarizing plate) 101 is provided on the outer main surface (the side opposite to the liquid crystal layer 105) of the first substrate 102, and the light from the backlight that irradiates the outer main surface is the polarizing plate 101. Is transmitted through the substrate 102 and then incident on the liquid crystal layer 105. A display circuit wiring layer 103 including a pixel electrode for applying an electric field to the liquid crystal layer 105 is provided on the inner main surface of the first substrate 102, and the straight line that passes through the liquid crystal layer 105 according to the electric field applied thereby. The direction of the polarization axis of polarized light changes. The light transmitted through the liquid crystal layer 105 enters the color filter layer 108 covered with the surface protective film 107, and components other than the specific wavelength band are blocked by the color filter layer 108. On the other hand, the component of the specific wavelength band is in accordance with the deviation between the polarization axis of the linearly polarized light and the side optical axis of the polarizing plate (external polarizing plate) 110 provided on the outer principal surface of the second substrate 109. The amount of light emitted from the polarizing plate 110 to the outside of the liquid crystal cell increases or decreases.

  The linearly polarized light transmitted through a part of the color filter layer 108 corresponding to a certain pixel is blocked by the polarizing plate 110 when the polarizing axis and the polarizing axis of the polarizing plate 110 are orthogonal to each other, and the pixel becomes darkest (blackened). When the polarization axes are oriented in the same direction, the light is transmitted through the polarizing plate 110 and the pixel is displayed brightest (for example, white). However, in practice, light may leak in principle even when black is displayed due to the relationship between the birefringence orientation of the liquid crystal layer 105 and the incident angle of linearly polarized light with respect to this. Therefore, in the liquid crystal display device, improvement in luminance (white luminance) particularly during white display and reduction in luminance (black luminance, so-called light leakage) during black display are dominant factors in the display contrast.

  The white luminance is important to increase the amount of light used for display through the liquid crystal display device from the backlight light source, but in the liquid crystal display device, it is shielded by the display circuit wiring, blue, green, red When color display is performed using a three-color filter, the wavelength range that the color filter can transmit with respect to visible light from the backlight light source is limited, and only １ ／ of the backlight light quantity is transmitted. The backlight light quantity cannot be used effectively, such as the problem of not being used.

  Patent Document 1 describes a technique using a wavelength conversion layer as a means for effectively using the amount of backlight light.

JP 2002-236209 A

  In the technique of the patent document using the wavelength conversion layer, the polarization property of the wavelength-converted light is not taken into consideration.

  Polarizing plates are bonded to the outer main surfaces of the two substrates sandwiching the liquid crystal forming the liquid crystal display device so that their polarization axes are optically orthogonal to each other. As a result, the light from the backlight light source passes through the polarizing plate located on the backlight side and becomes polarized light. When the light passes through the liquid crystal layer, the light rotates and is aligned with the axis of the other polarizing plate. The polarized light is transmitted through the polarizing plate and contributes to display. The wavelength conversion layer taught in Patent Document 1 is disposed as a layer made of a fluorescent material between the substrates.

  The fluorescent substance absorbs light and enters an excited state with a high energy level, and when the excitation energy is deactivated to the ground state, it emits energy as fluorescence, and the patent literature converts the wavelength of light. ing.

  However, the light that is normally emitted as fluorescence becomes non-polarized light, and light that deviates from the polarization axis leaks when passing through the polarizing plate. For this reason, the black luminance tends to become brighter, causing a decrease in contrast and deteriorating display performance.

  The above-mentioned problem is solved by the following means.

In a transmissive liquid crystal display device in which a liquid crystal layer is sandwiched between a first substrate and a second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate, the display is performed. Means:
A polarizing layer formed by orienting a dichroic dye in a uniaxial direction on the side facing the liquid crystal layer of the second substrate (for example, the main surface on the side of the liquid crystal layer) is a liquid crystal of the first substrate and the second substrate. An external polarizing plate is provided on each of the main surfaces opposite to the layers; and a liquid crystal layer is provided on the upper surface of the polarizing layer of the second substrate (the liquid crystal layer side of the polarizing layer) from the back surface of the first substrate. A wavelength conversion layer containing a substance that absorbs a component having a wavelength of 420 nm or less and transmits light having a wavelength of 420 nm or more is provided.

The second means is a transmissive liquid crystal in which a liquid crystal layer is sandwiched between the first substrate and the second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate to perform display. In the display device:
An external polarizing plate is provided on each side of the first substrate and the second substrate opposite to the liquid crystal layer (each main surface);
A polarizing layer formed by orienting a dichroic dye in a uniaxial direction on the side facing the liquid crystal layer of the second substrate (for example, the main surface on the liquid crystal layer side);
A color filter layer is provided on the upper surface of the polarizing layer of the second substrate (the liquid crystal layer side from the polarizing layer); and the wavelength of light of 420 nm or less that is transmitted through the liquid crystal layer from the back surface of the first substrate on the upper surface of the color filter layer A wavelength conversion layer containing a substance that absorbs components and emits light having a wavelength of 420 nm or more is provided.

A third means is a transmissive liquid crystal that displays an image by sandwiching a liquid crystal layer between a first substrate and a second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate. In the display device:
An external polarizing plate is provided on each side of the first substrate and the second substrate opposite to the liquid crystal layer (each main surface);
A polarizing layer formed by orienting a dichroic dye in a uniaxial direction on the side facing the liquid crystal layer of the second substrate (for example, the main surface on the liquid crystal layer side);
A color filter layer is provided on the upper surface of the polarizing layer of the second substrate (on the liquid crystal layer side of the polarizing layer);
The color filter layer has a black matrix pattern and blue, green, and red pigment dispersion color patterns; and each of the pigment dispersion color patterns (color filters) absorbs light in the visible light range and is longer than the absorbed light. It has a wavelength conversion function by containing a substance that emits light in the wavelength region on the wavelength side.

A fourth means is a transmissive liquid crystal that displays an image by sandwiching a liquid crystal layer between a first substrate and a second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate. In the display device:
An external polarizing plate is provided on the opposite side of the liquid crystal layer of the first substrate and the second substrate;
A polarizing layer formed by aligning a dichroic dye in a uniaxial direction on the side of the second substrate facing the liquid crystal layer;
A color filter layer is provided on the upper surface of the polarizing layer of the second substrate;
The color filter layer has a black matrix pattern and blue, green and red pigment dispersion color patterns;
The blue pattern contains a substance that absorbs light having a wavelength of 420 nm or less of light transmitted through the liquid crystal layer from the back surface of the first substrate and emits light having a wavelength of 420 nm or more,
The green pattern contains a substance that absorbs light having a wavelength of 460 nm or less and transmits light having a wavelength of 460 nm or more from the back surface of the first substrate.
The red pattern exhibits a wavelength conversion function by containing a substance that absorbs light having a wavelength of 550 nm or less and transmits light having a wavelength of 550 nm or more from the back surface of the first substrate.

  In a transmissive liquid crystal display device including any of the above-described means, an illuminating device (backlight) may be opposed to a main surface opposite to the liquid crystal layer of the first substrate, and the polarization axis of the polarizing layer may be The polarization axis of the polarizing plate on the second substrate is aligned with the same angle (overlapping each other in the main surface of the second substrate), and the polarization of the polarizing plate on the first substrate is aligned with one of the polarization axes The axis may be orthogonal.

  In the above-described liquid crystal display device, light incident on the wavelength conversion layer is absorbed by the liquid crystal display device, so that the wavelength is shifted to the longer wavelength side from the incident time, and light emitted from the wavelength conversion layer without polarization is polarized. Incident to the layer. The emitted light whose wavelength has been converted passes through the polarizing layer so that its non-polarized light component is shielded, and only the light (linearly polarized light) aligned with the polarization axis of the external polarizing plate is transmitted from the screen of the liquid crystal display device. The light is emitted and used for image display. Usually, visible light (for example, light having a wavelength band of 380 to 780 nm (nanometer)) incident on a liquid crystal display device (liquid crystal layer) from a backlight light source is blocked by a color filter except for a part of the wavelength band. It had been. However, in the present invention, light components that are shielded from light by the color filter, particularly components having a wavelength shorter than the above wavelength band, are converted into light having a longer wavelength by the wavelength conversion layer, and are effectively used as light emitted from the screen through the color filter. The As a result, the display performance (particularly the contrast ratio) of the liquid crystal display device is improved by improving the white luminance of the transmissive display by the screen and reducing the black luminance.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  A normal (known) liquid crystal display device to be compared with these is shown in FIG.

  One embodiment of a liquid crystal display device according to the present invention will be described as Example 1 with reference to FIG.

  On a glass substrate (first substrate) 202, a display circuit wiring layer 203 using a thin film transistor as a switching element is formed. The layer shown as the display device 203 includes, for example, a thin film transistor (field effect transistor), a wiring layer for applying a voltage signal to the source electrode (or drain electrode) and the gate electrode, and the drain electrode (or source electrode). And a pixel electrode that is connected to the liquid crystal layer and that faces the liquid crystal layer are not shown in detail. On the surface of the display circuit wiring layer (circuit layer) 203, a polyimide alignment film 204 for aligning liquid crystals (liquid crystal molecules forming the liquid crystal layer 205) is formed.

  A polarizing layer 211 is formed on the glass substrate (second substrate) 209, that is, on the inner main surface thereof (main surface on the liquid crystal layer 205 side) by applying the dichroic dye while being oriented. .

  At this time, the polarizing layer 211 is polarized in the same direction as the external polarizing plate 210 provided (for example, attached) on the outer main surface (main surface opposite to the liquid crystal layer 205) of the glass substrate 209. Has an axis.

  A color filter layer 208 for color display is formed on the polarizing layer 211. For the color filter layer 208, using a material in which carbon black is dispersed in a polymer, a black matrix (lattice-shaped light shielding pattern) and a material in which pigments of red, green, and blue are dispersed in a polymer material are used. A red (R), green (G), and blue (B) pattern is formed in combination.

  On the color filter layer 208, a wavelength conversion layer 207 that has an effect of flattening the surface and absorbs light of 420 nm or less and emits light of wavelength 420 nm or more is formed. On the wavelength conversion layer 207, a polyimide-based alignment film 206 for aligning liquid crystals (liquid crystal molecules constituting the liquid crystal layer 205) is formed.

  The glass substrate 202 and the glass substrate 209 are attached to each other at a peripheral portion (not shown) using an adhesive material called a sealing material, and the liquid crystal layer 205 is sandwiched between spaces between these substrates. As a result, a so-called liquid crystal cell (also called a liquid crystal panel or a liquid crystal display element) was obtained.

  Polarizers 201 and 210 are bonded to the outer main surfaces of the substrates 202 and 209 of the present liquid crystal cell, and a backlight unit (not shown) that opposes the liquid crystal cell to the outer main surface of the glass substrate (first substrate) 202. By combining with the above, a liquid crystal display device that performs transmissive display can be obtained.

  In the present liquid crystal display device, light having a luminance peak wavelength in the visible light region from the backlight unit passes through the polarizing plate 201 to become linearly polarized light, and enters the liquid crystal layer 205 through the glass substrate (first substrate). . When the linearly polarized light is transmitted through the liquid crystal layer 205, the polarization property (polarization axis) rotates and faces the same direction as the polarization axis of the external polarizing plate 210.

The light transmitted through the liquid crystal layer 205 enters the wavelength conversion layer 207. Since the wavelength conversion layer absorbs light of 420 nm or less incident thereon and emits light of wavelength 420 nm or more, the wavelength conversion layer 207 is incident on the color filter layer 208 (especially red, green, and blue patterns). The amount of light having a wavelength of 420 nm or more increases. The wavelength conversion layer 207 is, for example, a fluorescent dye coumarin 445 (C ₁₂ H ₁₃ NO ₂ ) which is a derivative of coumarin (C ₉ H ₆ O ₂ ), or LD425 (C ₁₃ H ₁₄ N) known as a laser dye. ₂ O ₃ ), Stilbene 420 (C ₂₈ H ₂₀ O ₆ S ₂ .2Na), Carbostyril 165 (C ₁₂ H ₁₄ N ₂ O). These chemical formulas are shown below.

  The physical properties of these materials can be examined on the website of Exciton (Dayton, Ohio, USA) (http://www.exciton.com/). For example, the coumarin 445 absorbs light (ultraviolet light) in a short wavelength band centered on 363 nm and emits fluorescence in a blue wavelength band centered on 430 nm. Laser dye: LD425 absorbs light in a short wavelength band centered on 357 nm (ultraviolet light) and emits fluorescence in a blue wavelength band centered on 427 nm. Laser dye: Stilbene 420 absorbs light in a short wavelength band centered on 349 nm (ultraviolet light) and emits fluorescence in a blue wavelength band centered on 425 nm. Laser dye: Carbostyril 165 absorbs light (ultraviolet light) in a short wavelength band centered on 360 nm and emits fluorescence in a blue wavelength band centered on 425 nm.

  The wavelength conversion layer 207 made of any of the above substances also transmits light in a long wavelength band, which is not absorbed by this, in a state where the linearly polarized light given by the external polarizing plate 201 is maintained, and enters the color filter layer 208. . In the color filter layer 208, components in a specific wavelength band of the linearly polarized incident light are transmitted while maintaining the linearly polarized light, and other components are absorbed. The component of the specific wavelength is emitted from the screen of the liquid crystal cell through the polarizing layer (built-in polarizing plate) 211, the glass substrate 209, and the polarizing plate 210 while maintaining linearly polarized light. On the other hand, blue non-polarized light is emitted from the wavelength conversion layer 207 that has absorbed ultraviolet light as described above. This light is not converted into linearly polarized light until it passes through the color filter layer 208 and enters the polarizing layer 211.

  There is no denying that the wavelength conversion layer 207 may lose a little by scattering the linearly polarized light in the visible region incident on the liquid crystal layer 205 from the liquid crystal layer 205 itself. Further, even if ultraviolet light that is not visually recognized by humans is visualized by the wavelength conversion layer 207, the wavelength band of the visible light that can be transmitted through the red, green, and blue color filter layers is limited. However, by changing short wavelength light such as ultraviolet light that was mostly absorbed by the color filter layer 208 into light having a wavelength of 420 nm or more in the wavelength conversion layer while being incident on the liquid crystal cell from a backlight or the like, the liquid crystal cell The amount of light emitted from the screen toward the viewer is larger than that of the liquid crystal cell without the wavelength conversion layer, and the brightness and contrast ratio of the display image are remarkably improved.

  The light generated in the wavelength conversion layer 207 is transmitted through the color filter layer without being polarized. A part of the light is blocked by the polarizing layer 211 and light having the same polarization axis as that of the polarizing layer 211 (linearly polarized light). Only transparent. Therefore, it seems that a part of the light generated in the wavelength conversion layer 207 is thrown away by the polarizing layer 211. However, by arranging the wavelength conversion layer 207 and the polarization layer 211 via the color filter layer 208, non-polarized light generated in a part of the wavelength conversion layer 207 corresponding to a certain pixel is adjacent to the pixel. This makes it difficult to leak to other pixels. That is, since the polarizing layer 211 is formed between the wavelength conversion layer 207 and the inner main surface of the substrate 209 on which the wavelength conversion layer 207 is formed, the non-polarized light generated in the wavelength conversion layer 207 passes through the color filter layer 208. As soon as it is changed to linearly polarized light by the polarizing layer 211, the radiation within the inner main surface of the substrate 209 can be suppressed. Further, the light generated in the pixel is blocked by the polarizing layer 211 even if the light is emitted from a part of the color filter layer 208 corresponding to another pixel. As a result, it is not difficult for the wavelength conversion layer 207 to distinguish between adjacent pixels. On the other hand, light generated in a certain pixel is converted into linearly polarized light by the polarizing layer 211 having the same polarization axis as that of the external polarizing plate 210, so that the portion of the external polarizing plate 210 corresponding to the pixel is almost lost. The light is transmitted without any contribution to the image display by the liquid crystal cell.

  As described in detail above, the wavelength conversion layer increases the amount of light having a wavelength of 420 nm or more, and the luminance is improved by increasing the amount of light that contributes to display.

  Another embodiment of the liquid crystal display device according to the present invention will be described as a second embodiment with reference to FIG.

  A display circuit wiring layer (circuit layer) 303 using a thin film transistor as a switching element is formed on a glass substrate (first substrate) 302. The details of the display circuit wiring layer 303 are substantially the same as those of the display circuit wiring layer 203 described in the first embodiment. On the surface of the display circuit wiring layer 303, a polyimide-based alignment film 304 for aligning liquid crystals (liquid crystal molecules forming the liquid crystal layer 305) is formed.

  A polarizing layer 311 is formed on the glass substrate (second substrate) 309, that is, on its inner main surface (main surface on the liquid crystal layer 305 side) by applying the dichroic dye while being oriented. .

  At this time, the polarizing layer 311 is polarized light having the same orientation as that of the external polarizing plate 310 provided (for example, attached) on the outer main surface (main surface opposite to the liquid crystal layer 305) of the glass substrate 309. Has an axis.

  A color filter layer for color display is formed on the polarizing layer 311. The color filter layer includes a black matrix lattice-shaped light shielding pattern 308 using a material in which carbon black is dispersed in a polymer, and a plurality of regions (for example, a plurality of regions formed in the light shielding pattern 308) partitioned by the light shielding pattern 308. The red (R) color filter 312, the green (G) color filter 313, and the blue (B) color filter 314, respectively. These color filters 312, 313, 314 are characterized as follows.

The red (R) color filter 312 fills the openings of the light shielding pattern 308 with a polymer material containing a substance in which a red pigment is dispersed and which absorbs light having a wavelength of 550 nm or less and emits light having a wavelength of 550 nm or more. It shows a so-called wavelength conversion function that is formed and converts light having a wavelength shorter than the red wavelength band into light of the red wavelength band or longer. As the wavelength conversion material, its chemical formula is a kind of Keaton Red _{620 (KitonRed 620, C 27 H} 29 N 2 NaO 7 S 2) or fluorescein-based dye represented below 2 ', 7'-dichloro-fluorescein (2 ′, 7′-Dichlorofluorescein (DCF), C ₂₀ H ₁₀ Cl ₂ O ₅ ) is used.

The physical properties of these materials are also available on the Exciton website described above. In addition to the above two types of wavelength converting substances that can be added to the red color filter 312, coumarin dyes such as NKX2288, NKX2222, NK2585, NK2687, and NK529, DCM ([2- [2- [4- (dimethylamino) phenyl] ethenyl] -6-methyl-4H-pyran-4-ylidene] -propanedinitrile, C ₁₉ H ₁₇ N ₃ O), Nile Blue A perchlorate, IUPAC name = 5-Amino-9 -diethyliminobenzo [a] phenoxazonium perchlorate), 1,1 ', 3,3,3', 3'-hexamethylindotricarbocyanine (1,1 ', 3,3,3', 3'-Hexamethylindotricarbocyanine) perchlorate), perchlorate 1,1 ′, 3,3,3 ′, 3′-hexamethyl-4,4 ′, 5,5′-dibenzo-2,2′-indotricarbocyanine (1,1 ′, 3,3,3 ', 3'-Hexamethyl-4,4', 5, 5'-dibenzo-2,2'-indotricarbocyanine perchlorate), crystal bio Perchloric acid of pigments such as Crystal Violet, Oxazine 4, Oxazine 170, Oxazine 1, and Pyridine 1, Styryl 7, Styryl 7, Pyridine 2, Red GG Laser dyes such as (Red GG, IUPAC name = 4-Nitrobenzenediazonium tetrafluoroborate), and Red 5B can also be used.

The green (G) color filter 313 is obtained by filling the openings of the light shielding pattern 308 with a polymer material containing a substance in which a green pigment is dispersed and which absorbs light having a wavelength of 460 nm or less and emits light having a wavelength of 460 nm or more. It shows a so-called wavelength conversion function for converting light having a wavelength shorter than the blue-green wavelength band into light of the blue-green wavelength band or longer. As this wavelength conversion substance, coumarin 120 (Coumarin 120, C ₁₀ H ₉ NO ₂ ) whose chemical formula is shown below, 1,4-bis-2- (4-methyl-5-phenyloxazolyl) benzene ( Also referred to as DMPOPOP or Dimethyl-POPOP, IUPAC name = 4-methyl-2- [4- (4-methyl-5-phenyl-1,3-oxazol-2-yl) phenyl] -5-phenyl-1,3- oxazole (C ₂₆ H ₂₀ N ₂ O ₂ )) or 2-quinolinol (2-Quinolinol, IUPAC name = 1H-quinolin-2-one (C ₉ H ₇ NO)) may be used.

In addition to the above three types, wavelength conversion substances that can be added to the green color filter 313 include coumarin dyes such as coumarin 545, coumarin 153, coumarin 6, coumarin 2, coumarin 4, coumarin 30, coumarin 535, NKX2068, NKX2204, Pyrromethene 597 (Pyrromethene 597), pyromethene 580, pyromethene 546, pyromethene 567, and the like, thioflavin T (Thioflavin T, IUPAC name = 4- (3,6-dimethyl-1), also called Basic Yellow 1 , 3-benzothiazol-3-ium-2-yl) -N, N-dimethylaniline chloride (C ₁₇ H ₁₉ ClN ₂ S)), auramine called basic yellow 2 (IUPAC name = 4- (4-dimethylaminobenzenecarboximidoyl)- N, N-dimethylaniline hydrochloride), also known as disazo yellow or pigment yellow 17. Raw 3G (Yellow 3G, IUPAC name = trisodium 2,5-dichloro-4-[(4Z) -4-[[5-[[4-chloro-6-[(4-sulfonatophenyl) amino] -1,3, 5-triazin-2-yl] amino] -2-sulfonatophenyl] hydrazinylidene] -3-methyl-5-oxopyrazol-1-yl] benzenesulfonate), calcein blue (Calcein Blue, IUPAC name = 2- [carboxymethyl- [(7-hydroxy-4- methyl-2-oxochromen-8-yl) methyl] amino] acetic acid (C 15 H 15 NO 7)), 1,4- bis (2-methylstyryl) benzene (bis-MSB ), Fluorol 555, Fluorescein 548 (Fluorescein 548, IUPAC name = 3 ′, 6′-dihydroxyspiro [2-benzofuran-3,9′-xanthene] -1-one) Good.

The blue (B) color filter 314 is obtained by filling the openings of the light-shielding pattern 308 with a polymer material containing a substance in which a blue pigment is dispersed and which absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more. It shows a so-called wavelength conversion function for converting light having a wavelength shorter than the blue-violet wavelength band into light having a wavelength in the blue wavelength band or longer. As this wavelength converting substance, coumarin 445, LD425, stilbene 420, and carbostyryl 165 mentioned in Example 1 are used. In addition, the following materials are also used. The first group includes Coumarin 1, IUPAC name = 7-Diethylamino-4-methylcoumarin, Coumarin 4, Coumarin 102, Coumarin 106, Coumarin 481, Coumarin 485, Coumarin 490, Coumarin 498, Coumarin 500, It consists of coumarin dyes such as coumarin 503, coumarin 504, coumarin 510, coumarin 521, coumarin 523, coumarin 525, NKX1637. The second group consists of LD466 (IUPAC name = 7- (diethylamino) -2H-1-benzopyran-2-one, C ₁₃ H ₁₅ NO ₂ ), LD473 (IUPAC name = 1,2,3,8-tetrahydro). -1,2,3,3,8-pentamethyl-5- (trifluoromethyl) -7H-pyrrolo [3,2-g] quinolin-7-one, C ₁₇ H ₁₉ F ₃ N ₂ O), LD490 (IUPAC name) = 2,3,6,7-tetranydro-1H, 5H, 11H- [1] benzopyrano [6,7,8-ij] -quinoliz-11-one, C ₁₅ H ₁₅ NO ₂ ) . In addition to these groups, perylene (C ₂₀ H ₁₂ ) may be used as the wavelength converting substance.

  Next, in order to flatten the surface of the color filter layer (particularly the undulation caused by the light shielding pattern 308 and the plurality of types of color filters 312, 313, 314) and to separate the color filter layer from the liquid crystal layer, A protective layer 307 is formed. Further, a polyimide-based alignment film 306 for aligning the liquid crystal forming the liquid crystal layer 305 in a predetermined direction with respect to the main surface of the substrate 309 is formed on the protective layer 307.

  The glass substrate 302 and the glass substrate 309 are attached to each other at a peripheral portion (not shown) using an adhesive material called a sealant, and the liquid crystal 305 is sealed in a space between the substrates. Of course, before the pair of substrates 302 and 309 are bonded together, the liquid crystal is dropped on one main surface, and then the liquid crystal is sandwiched between the main surfaces of the pair of substrates 302 and 309 to bond them together. Also good. Through the above steps, the liquid crystal cell of this example was obtained.

  Polarizing plates 301 and 310 are bonded to the outer main surfaces of the substrates 302 and 309 of the liquid crystal cell, and the liquid crystal cell is connected to a backlight unit (not shown) facing the outer main surface of the substrate (first substrate) 302. By combining them, a liquid crystal display device that performs transmissive display can be obtained.

  In the present liquid crystal display device, light having a luminance peak wavelength in the visible light region from the backlight unit passes through the polarizing plate 301 to be linearly polarized light, and enters the liquid crystal layer 305 through the substrate (first substrate). When this linearly polarized light is transmitted through the liquid crystal layer 305, the polarization property (polarization axis) rotates and faces the same direction as the polarization axis of the external polarizing plate 310.

  The light transmitted through the liquid crystal layer 305 enters the red, green, and blue color filters 312, 313, and 314.

  In the pixel provided with the red color filter 312, the linearly polarized light transmitted through the liquid crystal layer 305 includes components of wavelengths other than red. Among the light components, “light having a wavelength shorter than the red wavelength band” is easily absorbed by the red pigment contained in the color filter 312, and thus the color filter 312 is particularly light having a wavelength range of 550 nm or less. On the other hand, it shows a low transmittance. However, in the present invention, the light in the wavelength region of 550 nm or less that has been discarded by the red color filter 312 until now is absorbed by the wavelength conversion material added to the red color filter, and the wavelength 550 nm according to this absorption. By emitting the above light from the wavelength converting substance, the amount of light transmitted through the red color filter 312 is increased.

  Not only the red color filter but also the intensity of the incident light to the liquid crystal cell linearly polarized by the polarizing plate 301 and propagated by the liquid crystal layer 305 is the specific wavelength band (the color filter has a high light transmittance). It must be reduced by absorption by a color filter other than the components in the wavelength band shown. However, the effect of suppressing the attenuation of the light finally emitted from the liquid crystal cell by converting the component of the incident light on the shorter wavelength side than the specific wavelength band into light having the wavelength in the band is red. It can also be obtained with other color filters.

  In the pixel provided with the green color filter 313, the wavelength of the “component having a wavelength shorter than the green wavelength band (light in the wavelength band from blue to ultraviolet)” of the linearly polarized light transmitted through the liquid crystal layer 305 is converted. The green light is emitted from the liquid crystal cell. Light having a wavelength shorter than green to be wavelength-converted is easily absorbed by the green pigment. Therefore, the color filter 313 exhibits a low transmittance particularly for light having a wavelength region of 460 nm or less. However, in the present invention, light in a wavelength region of 460 nm or less that has been discarded by the green color filter 313 until now is absorbed by the wavelength conversion material added to the green color filter, and the wavelength is 460 nm according to this absorption. The amount of light transmitted through the green color filter 313 is increased by emitting the above light from the wavelength converting substance.

  Similarly, in the pixel provided with the blue color filter 314, the wavelength of the “component having a wavelength shorter than the blue wavelength band (light in the wavelength band from violet to ultraviolet)” of the linearly polarized light transmitted through the liquid crystal layer 305 is set. The light is converted and emitted from the liquid crystal cell as blue light. Light having a wavelength shorter than that of blue is easily absorbed and lost not only by the green pigment but also by impurities in the color filter 314 because of its high energy. For this reason, the color filter 314 exhibits a low transmittance particularly for light in a wavelength region of 420 nm or less. However, in the present invention, light in a wavelength region of 420 nm or less that has been discarded by the blue color filter 314 until now is absorbed by the wavelength conversion material added to the blue color filter, and the wavelength of 420 nm according to this absorption. By emitting the above light from the wavelength converting substance, the amount of light transmitted through the blue color filter 314 is increased.

  The wavelength (lower limit value) of light generated by the wavelength conversion in each of the color filters 312 to 314 can be adjusted as appropriate according to the color display mode in the liquid crystal cell. For example, light of 410 nm or more may be generated by a blue color filter to emphasize “blueness” in the display image of the liquid crystal cell.

  In each of the red, green, and blue color filters 312 to 314, the light generated by the wavelength conversion of the incident light (linearly polarized light) is non-polarized light, and is a medium (color filter in this embodiment) as compared with the linearly polarized light. Is propagated in any direction. This problem is common not only to the specific wavelength converting material described above but also to all materials exhibiting such functions. For this reason, it cannot be denied that a part of the light generated by the wavelength conversion leaks from the darkly displayed pixel. In this embodiment, the wavelength conversion corresponding to each pixel is performed by the color filters 312 to 314 formed in the opening of the light shielding pattern 308 that separates the pixels. For this reason, the non-polarized light is blocked by the light blocking pattern 308 and hardly leaks to surrounding pixels.

  A polarizing layer 311 is formed between the color filters 312 to 314 and the main surface of the substrate 309 on which these are formed. For this reason, the unpolarized light generated in the color filters 312 to 314 is converted into linearly polarized light by the polarizing layer 311 before being diffused in the main surface, and the unpolarized component that is not desired is polarized in the polarizing layer 311. Shielded with light. In a so-called normally black driving liquid crystal cell in which the liquid crystal layer 305 is darkest when no electric field is applied, the liquid crystal layer 305 is provided on the outer main surface of the substrate 309 that emits light transmitted through the liquid crystal layer 305. The polarization axis of the polarizing plate 310 intersects with the polarization axis of linearly polarized light transmitted through the liquid crystal layer 305 to which no electric field is applied at the maximum angle (maximum 90 °) and transmits through the liquid crystal layer 305 to which the strongest electric field is applied. It is oriented in the direction that intersects the polarization axis of linearly polarized light at the smallest angle (minimum 0 °). Since the polarization layer 311 is formed with its polarization axis aligned with the orientation of the polarization axis of the polarizing plate 310, the light generated by the color filters 312 to 314 is polarized only by the component linearly polarized by the polarization layer 311. The light is transmitted through the plate 310 and emitted from the liquid crystal cell, thereby contributing to image display.

  As described in detail above, in this embodiment, the wavelength of the incident light is converted for each pixel, and the amount of light emitted from each pixel is increased, which contributes to image display over the entire screen of the liquid crystal cell. Increase the display brightness.

  Another embodiment of the liquid crystal display device according to the present invention will be described as a third embodiment with reference to FIG.

  A display circuit wiring layer (circuit layer) 403 having a thin film transistor as a switching element is formed on a glass substrate (first substrate) 402; a liquid crystal (a liquid crystal forming a liquid crystal layer 405) is formed on the surface of the display circuit wiring layer 403. A polyimide-based alignment film 404 for aligning molecules); polarized on the outer main surface (main surface opposite to the liquid crystal layer 405) of the glass substrate 402 and the glass substrate (second substrate) 409. Plates (external polarizing plates) 401 and 410 are respectively provided; a polarizing layer 411 is formed by applying a dichroic dye while being oriented on the inner main surface (liquid crystal layer 405 side) of the glass substrate 409. And that the polarizing axes of the polarizing layer 411 and the external polarizing plate 410 are oriented in the same direction, the liquid crystal cell described in this example is the same as in Example 1 and Example 1. Common to the liquid crystal cell described in 2.

  On the polarizing layer 411, a color filter layer for displaying a color image by the liquid crystal cell is formed. The color filter layer includes a black matrix (lattice-shaped light shielding pattern) 408 formed using a material in which carbon black is dispersed in a polymer, and a plurality of regions (for example, light shielding pattern 408 formed by the light shielding pattern 408). Each of the formed openings) includes a red (R) color filter 412, a green (G) color filter 413, and a blue (B) color filter 414. These color filters 412, 413, 414 are characterized as follows.

  The red (R) color filter 412 includes a polymer material containing a substance (wavelength converting substance) in which a red pigment is dispersed and which absorbs light having a wavelength of 550 nm or less and emits light having a wavelength of 550 nm or more. A so-called wavelength conversion function is shown which is formed by filling the aperture and converts light having a wavelength shorter than the red wavelength band into light having the red wavelength band or longer wavelength. The green (G) color filter 413 is a light-shielding pattern 408 made of a polymer material containing a substance (wavelength conversion substance) in which a green pigment is dispersed and which absorbs light having a wavelength of 460 nm or less and emits light having a wavelength of 460 nm or more. The wavelength conversion function is formed by filling the aperture of the light and converting light having a wavelength shorter than the blue-green wavelength band into light having a wavelength of blue-green or longer. The blue (B) color filter 414 uses a polymer material containing a substance (wavelength conversion substance) in which a blue pigment is dispersed and which absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more as a light-shielding pattern 408. The wavelength conversion function is formed by filling the aperture and converting light having a wavelength shorter than the blue-violet wavelength band into light having a wavelength in the blue wavelength band or longer.

  The structures and characteristics of the red color filter 412, the green color filter 413, and the blue color filter 414 formed on the polarizing layer 411 are the same as the red color filter 312, the green color filter 313, and the blue color filter described in the second embodiment. The “wavelength converting substance” which is the same as each of 314 and is added to each of the color filters 412 to 414 is also listed in Example 2.

  However, in the liquid crystal cell of this example, the “wavelength conversion layer 407 that absorbs light of 420 nm or less and emits light of wavelength 420 nm or more” is provided on the “color filter layer” composed of the light shielding pattern 408 and the color filters 412 to 414. By being formed, it is different from the liquid crystal cell described in the second embodiment. Similar to the protective layer 307 in the second embodiment, the wavelength conversion layer 407 has an effect of flattening unevenness caused by the light shielding pattern 408, the color filters 412 to 41, and the like generated on the upper surface of the color filter layer. A polyimide-based alignment film 406 for aligning the liquid crystal in the liquid crystal layer 405 in a predetermined orientation with respect to the main surface of the substrate 409 is formed on the wavelength conversion layer 407. After that, the glass substrate 402 and the glass substrate 409 are bonded to each other at a peripheral portion (not shown) using an adhesive material called a sealing material, and the liquid crystal 405 is sealed in a space between the substrates. Through the above steps, the liquid crystal cell of this example was obtained.

  Furthermore, polarizing plates 401 and 410 are bonded to the outer main surfaces of the substrates 402 and 409 of the present liquid crystal cell, and this liquid crystal cell is combined with a backlight unit (not shown) facing the outer main surface of the substrate 402. A liquid crystal display device that performs transmissive display is obtained.

  In the liquid crystal display device of this embodiment, light having a luminance peak wavelength in the visible light region radiated from the backlight unit passes through the polarizing plate 401 and is linearly polarized, and the linearly polarized light passes through the liquid crystal layer 405. Further, the polarization property (polarization axis) is rotated and oriented in the same direction as the polarization axis of the external polarizing plate 410.

  The light transmitted through the liquid crystal layer 405 enters the wavelength conversion layer 407. Since the wavelength conversion layer 407 absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more, the amount of light having a wavelength of 420 nm or more increases. For example, when the wavelength conversion layer 407 includes coumarin 445 as a wavelength conversion substance and any of laser dyes: LD425, stilbene 420, and carbostyril 165, linearly polarized ultraviolet light incident on the wavelength conversion layer 407 is 425. The light is emitted from the wavelength conversion layer 407 as non-polarized light (blue fluorescence) in a wavelength band centered at ˜430 nm. When the wavelength conversion layer 407 includes at least one of the four types of wavelength conversion materials, the wavelength band of light emitted from the wavelength conversion layer 407 does not stay within the so-called blue light wavelength band, and exceeds this to the longer wavelength side. Can spread. Accordingly, the intensity of the emitted light from the wavelength conversion layer 407 is recognized to increase even in the wavelength band corresponding to red light and green light, although not as high as the wavelength band of blue light.

Light that has passed through the wavelength conversion layer and has an increased amount of light in the visible wavelength region is incident on the red, green, and blue color filters 412, 413, and 414, respectively. The wavelength conversion materials added to these color filters 412 to 414 exhibit high wavelength conversion efficiency with respect to the ultraviolet light incident thereon, like the four types of wavelength conversion materials added to the wavelength conversion layer 407. Not necessarily. For example, when DCM described in Example 2 is added to the red color filter 412, the red color filter 412 absorbs light in a wavelength band centered on 481 nm (blue green), and the so-called red wavelength centered on 644 nm. Emits fluorescence in the band. In addition, Fluorol 555 (IUPAC name: 2-butyl-6- (butylamino) -1H-benz [de] isoquinoline-1,3 (2H) -dione, C ₂₀ H ₂₄ N ₂ O ₂ ) is added to the green color filter 413. When added, the green color filter 413 absorbs light in a wavelength band centered on 442 nm (blue) and emits fluorescence in a so-called green wavelength band centered on 536 nm. Furthermore, the blue color filter 414 to which the laser dye: LD490 described in Example 2 is added absorbs light in a wavelength band centered on 396 nm (purple) and has a blue wavelength band centered on 474 nm. Fluoresce.

  The wavelength converting substances that can be added to the color filters 412 to 414 of the liquid crystal cell according to the present embodiment and exhibit high wavelength conversion efficiency with respect to incident light having a wavelength in the visible region are not limited to the above three types. There is a wide variety. When such color filters 412 to 414 are irradiated with light from a backlight that is not discriminated in a specific wavelength band, the amount of wavelength light that can be absorbed by the wavelength conversion material is limited. The emitted light also remains in a slight amount. In other words, depending on the type of the wavelength converting substance, the amount of light emitted from the color filter to which it is added (for example, red light) is almost the same as the amount of light emitted from the color filter to which this is not added. Sometimes.

  However, in the liquid crystal cell of this embodiment in which the wavelength conversion layer 407 is disposed in front of the color filters 412 to 414 to which the wavelength conversion material is added (on the light source side), for example, a red pigment is included, so Even if the color filter 412 has a low transmittance with respect to light in the wavelength band, light in the wavelength band of 550 nm or less generated by the backlight is converted into red light by the wavelength conversion layer 407 and / or the color filter 412. Therefore, the amount of light transmitted through the red color filter 412 increases. Similarly, even if the color filter 413 shows a low transmittance with respect to light in the wavelength range of 460 nm or less because it contains a green pigment, the light in the wavelength band of 460 nm or less generated by the backlight is wavelength-converted. Since the light is converted into green light by the layer 407 and / or the color filter 413, the amount of light transmitted through the green color filter 413 increases. Further, even if the color filter 414 has a low transmittance with respect to light in a wavelength region of 420 nm or less because it contains a blue pigment, the light in the wavelength band of 420 nm or less generated by the backlight is converted into the wavelength conversion layer. Since the light is converted into blue light by 407 and / or the color filter 414, the amount of light transmitted through the blue color filter also increases.

  The amount of light transmitted through the red, green, and blue color filters 412 to 414 has increased compared to a conventional liquid crystal cell due to wavelength conversion in one of the color filters and / or the wavelength conversion layer 407 in the preceding stage. Among them, a non-polarized light component resulting from the wavelength conversion is also included. The non-polarized component of the light generated by the wavelength conversion is shielded by the polarizing layer 411 adjacent to the color filter layer, and is added to the linearly polarized light passing through the color filter without being wavelength-converted as an increment of the linearly polarized light. These linearly polarized lights have a polarization axis oriented in the same direction as these polarization axes and pass through the external polarizing plate 410 provided on the outer principal surface of the substrate 409, contributing to image display in the liquid crystal cell. To do.

  As described above in detail, in this embodiment, the wavelength conversion of the light incident on the liquid crystal cell is performed in two stages, immediately after the incident light is transmitted through the liquid crystal layer and after the incident light is distributed for each pixel. By doing so, the amount of light contributing to the image display of the liquid crystal cell is further increased, and the display luminance is improved.

  Another embodiment of the liquid crystal display device according to the present invention will be described as a fourth embodiment with reference to FIG.

  A display circuit wiring layer (circuit layer) 503 having a thin film transistor as a switching element is formed on a glass substrate (first substrate) 502; liquid crystal (liquid crystal forming the liquid crystal layer 505) is formed on the surface of the display circuit wiring layer 503. A polyimide-based alignment film 504 for aligning molecules); polarized on the outer principal surfaces (major surfaces opposite to the liquid crystal layer 505) of the glass substrate 502 and the glass substrate (second substrate) 509. Plates (external polarizing plates) 501 and 510 are respectively provided; on the inner main surface (the liquid crystal layer 505 side) of the glass substrate 509, a polarizing layer 511 is formed by applying a dichroic dye while being oriented. And the polarizing axes of the polarizing layer 511 and the external polarizing plate 510 are oriented in the same direction, so that the liquid crystal cell described in this embodiment is the same as that of the first to third embodiments. Common to the liquid crystal cell described in s.

  On the polarizing layer 511, similarly to the liquid crystal cell of Example 1, a color filter layer for color image display by the liquid crystal cell is formed. The color filter layer includes a black matrix (lattice-shaped light shielding pattern) 508 formed using a material in which carbon black is dispersed in a polymer, and a plurality of regions (for example, light shielding pattern 508 formed by the light shielding pattern 508). Each of the formed openings) includes a red (R) color filter 512, a green (G) color filter 513, and a blue (B) color filter 514. In the liquid crystal cell of this embodiment, light having a wavelength of 550 nm or less is absorbed on a red color filter 512 in which a red pigment is dispersed in each of a plurality of openings formed in the light shielding pattern 508, and light having a wavelength of 550 nm or more. The wavelength conversion layer 515 made of a polymer material containing a substance that emits light contains a substance that absorbs light having a wavelength of 460 nm or less and emits light having a wavelength of 460 nm or more on the green color filter 513 in which the green pigment is dispersed. The wavelength conversion layer 516 made of a polymer material has a wavelength conversion made of a polymer material containing a substance that absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more on the blue color filter 514 in which a blue pigment is dispersed. Each layer 517 is characterized by a stacked structure. The wavelength conversion layer 515 is, for example, the “wavelength conversion substance” added to the “red color filter 312” described in the second embodiment, and the wavelength conversion layer 516 is, for example, the “green color filter 313, which is described in the second embodiment. The wavelength conversion layer 517 is added to the wavelength conversion layer 207 described in Example 1 or the “blue color filter 314” described in Example 2, for example. "Substance" respectively.

  On the “color filter layer” composed of the light shielding pattern 508, the color filters 512 to 514, and the wavelength conversion layers 515 to 517, the surface of the color filter layer is flattened and the color filter layer is separated from the liquid crystal layer. Layer 507 is formed. A polyimide-based alignment film 506 for aligning the liquid crystal in the liquid crystal layer 505 in a predetermined orientation with respect to the main surface of the substrate 509 is formed on the protective layer 507. After that, the glass substrate 502 and the glass substrate 509 are attached to each other at a peripheral portion (not shown) using an adhesive material called a sealing material, and the liquid crystal 505 is sealed in a space between the substrates. Through the above steps, the liquid crystal cell of this example was obtained.

Further, polarizing plates 501 and 510 are bonded to the outer main surfaces of the substrates 502 and 509 of the present liquid crystal cell, and this liquid crystal cell is combined with a backlight unit (not shown) facing the outer main surface of the substrate 502, In the liquid crystal cell of this example, the liquid crystal cell of this example is described as “integrated with a color filter containing a wavelength conversion material corresponding to its transmission wavelength band” described in Example 2 and Example 3. The “all-in-one structure” is divided into a “color filter (wavelength discrimination layer)” and a “wavelength conversion layer”. Further, the wavelength conversion layers 515 to 517 and the color filters 512 to 514 are laminated in this order from the liquid crystal layer 505 side. When these laminated structures are formed in the opening of the light shielding pattern 508, the wavelength conversion layers 515 to 517 including the wavelength conversion material are the color filters 312 to 314 and 412 including the wavelength conversion material in the second and third embodiments. Thinner than ~ 414. However, it cannot be denied that the wavelength profile of the light generated in the wavelength conversion layers 515 to 517 exceeds the wavelength band that should be transmitted by each of the color filters 512 to 514. For this reason, in the liquid crystal cell of the present embodiment in which the color filters 512 to 514 are arranged in the subsequent stage of the wavelength conversion layers 515 to 517, the light outside the wavelength region that can be generated in the wavelength conversion layers 515 to 517 is emitted from the color filters 512 to 512. By blocking at 514, noise in the display screen of the liquid crystal cell and a decrease in contrast ratio due to this are suppressed.

  Therefore, the liquid crystal cell of this embodiment can display a clear image with little noise.

  Another embodiment of the liquid crystal display device according to the present invention will be described as a fifth embodiment with reference to FIG.

  A display circuit wiring layer (circuit layer) 603 having a thin film transistor as a switching element is formed on a glass substrate (first substrate) 602; a liquid crystal (a liquid crystal forming a liquid crystal layer 605) is formed on the surface of the display circuit wiring layer 603. A polyimide-based alignment film 604 for aligning molecules); polarized on the outer main surface (main surface opposite to the liquid crystal layer 605) of the glass substrate 602 and the glass substrate (second substrate) 609. Plates (external polarizing plates) 601 and 610 are respectively provided; a polarizing layer 611 is formed by applying a dichroic dye while being oriented on the inner main surface (the liquid crystal layer 605 side) of the glass substrate 609. And that the polarizing axes of the polarizing layer 611 and the external polarizing plate 610 are oriented in the same direction, so that the liquid crystal cell described in this embodiment is the same as that of the first to fourth embodiments. Common to the liquid crystal cell described in s.

  On the polarizing layer 611, similarly to the liquid crystal cell of Example 4, a color filter layer for displaying a color image by the liquid crystal cell is formed. The color filter layer includes a black matrix (lattice-shaped light shielding pattern) 608 formed using a material in which carbon black is dispersed in a polymer, and a plurality of regions (for example, light shielding pattern 608 formed by the light shielding pattern 608). A stacked structure of a red (R) color filter 612 and a wavelength conversion layer 615 that emits red light, and a green (G) color filter 613 and wavelength conversion that emits green light, respectively. A layered structure with the layer 616, and a layered structure with a blue (B) color filter 614 and a wavelength conversion layer 617 that emits blue light. The wavelength conversion layer 615 that emits red light is made of a polymer material containing a substance that absorbs light having a wavelength of 550 nm or less and emits light having a wavelength of 550 nm or more. The wavelength conversion layer 616 that emits green light is made of a polymer material containing a substance that absorbs light having a wavelength of 460 nm or less and emits light having a wavelength of 460 nm or more. The wavelength conversion layer 617 that emits blue light is made of a polymer material containing a substance that absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more.

  In the liquid crystal cell of this example, the surface is flattened on the “color filter layer” composed of the light shielding pattern 608, the color filters 612 to 614, and the wavelength conversion layers 615 to 617 (the unevenness of the surface is made uniform); The wavelength conversion layer 607 that absorbs light of 420 nm or less and emits light of wavelength 420 nm or more is formed, which is different from the liquid crystal cell of Example 4. A polyimide-based alignment film 606 for aligning the liquid crystal in the liquid crystal layer 605 in a predetermined orientation with respect to the main surface of the substrate 609 is formed on the wavelength conversion layer 607. After that, the glass substrate 602 and the glass substrate 609 are bonded to each other at a peripheral portion (not shown) using an adhesive material called a sealing material, and the liquid crystal 605 is sealed in a space between the substrates. Through the above steps, the liquid crystal cell of this example was obtained.

Furthermore, polarizing plates 601 and 610 are bonded to the outer principal surfaces of the substrates 602 and 609 of the present liquid crystal cell, and by combining this liquid crystal cell with a backlight unit (not shown) facing the outer principal surface of the substrate 602, A liquid crystal display device that performs transmissive display is obtained. The liquid crystal cell of this embodiment has a color filter layer in which a laminated structure of a “color filter (wavelength discrimination layer)” and a “wavelength conversion layer” is provided for each pixel. Thus, although common to the liquid crystal cell of Example 4, the wavelength conversion layer 607 extending over all pixels is formed in the previous stage (on the liquid crystal layer 605 side) of the wavelength conversion layers 615 to 617. Therefore, as described in the third embodiment, the short wavelength light such as ultraviolet light generated by the backlight and linearly polarized by the polarizing plate 601 is converted into visible light by the wavelength conversion layer 617, thereby converting the wavelength. The layers 615 to 617 facilitate the emission of red light, green light, and blue light. That is, as described in Example 3, particularly in a wavelength conversion material that generates red light and green light by absorption of incident light, the wavelength band in which the incident light is easily absorbed overlaps the visible region, and particularly from blue to green. This is because visible light on the short wavelength side applied to the light promotes light emission by the wavelength converting substance.

  Therefore, in the liquid crystal cell of this embodiment, a clear image with less noise is displayed, and the “white luminance” of the screen is further improved.

  In the present invention, a liquid crystal cell for transmissive display provided with a pair of external polarizing plates on the front and back thereof is simply provided with a polarizing layer and a wavelength conversion layer on one side of the light emission side of the substrate (transparent substrate). Conventionally, light in a wavelength band that is blocked by a color filter or is not visually recognized by a human is used for image display. Thus, without increasing the power consumption of the backlight combined with the liquid crystal cell, the white luminance of the transmissive display in the liquid crystal display device constituted by these is improved and the black luminance is lowered. As a result, a liquid crystal display device with low energy consumption and high image display performance is realized.

Sectional drawing for demonstrating the conventional liquid crystal display device. Sectional drawing for demonstrating the liquid crystal display device by Example 1 of this invention. Sectional drawing for demonstrating the liquid crystal display device by Example 2 of this invention. Sectional drawing for demonstrating the liquid crystal display device by Example 3 of this invention. Sectional drawing for demonstrating the liquid crystal display device by Example 4 of this invention. Sectional drawing for demonstrating the liquid crystal display device by Example 5 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... External polarizing plate, 102 ... 1st board | substrate, 103 ... Display circuit wiring layer, 104 ... Liquid crystal aligning film, 105 ... Liquid crystal layer, 106 ... Liquid crystal aligning film, 107 ... Color filter layer surface protective film, 108 ... Color Filter layer 109 109 Second substrate 110 External polarizing plate 201 External polarizing plate 202 First substrate 203 Display circuit wiring layer 204 Liquid crystal alignment layer 205 Liquid crystal layer 206 DESCRIPTION OF SYMBOLS ... Liquid crystal aligning film, 207 ... Wavelength conversion layer, 208 ... Color filter layer, 209 ... Second substrate, 210 ... External polarizing plate, 211 ... Built-in polarizing plate, 301 ... External polarizing plate, 302 ... First substrate , 303 ... Display circuit wiring layer, 304 ... Liquid crystal alignment film, 306 ... Liquid crystal layer, 306 ... Liquid crystal alignment film, 307 ... Color filter layer surface protective film, 308 ... Black matrix pattern, 309 ... Second Plate, 310 ... External polarizing plate, 311 ... Built-in polarizing plate, 312 ... Red color filter with wavelength conversion function, 313 ... Green color filter with wavelength conversion function, 314 ... Blue color filter with wavelength conversion function, 401 ... External polarization Plate 402: First substrate 403 Display circuit wiring layer 404 Liquid crystal alignment film 405 Liquid crystal layer 406 Liquid crystal alignment film 407 Wavelength conversion layer 408 Black matrix pattern 409 Second Substrate, 410 ... External polarizing plate, 411 ... Built-in polarizing plate, 412 ... Red color filter with wavelength conversion function, 413 ... Green color filter with wavelength conversion function, 414 ... Blue color filter with wavelength conversion function, 501 ... External polarization Plate 502 502 First substrate 503 Display circuit wiring layer 504 Liquid crystal alignment film 505 Liquid crystal layer 506 Liquid Alignment film, 507... Color filter layer surface protective film, 508... Black matrix pattern, 509... Second substrate, 510 ... external polarizing plate, 511 .. built-in polarizing plate, 512 ... red color filter, 513 ... green color filter, 514 ... Blue color filter, 515 ... Red wavelength conversion layer, 516 ... Green wavelength conversion layer, 517 ... Blue wavelength conversion layer, 601 ... External polarizing plate, 602 ... First substrate, 603 ... Display circuit wiring layer, 604 ... Liquid crystal alignment film, 605 ... Liquid crystal layer, 606 ... Liquid crystal alignment film, 607 ... Color filter layer surface protective film, 608 ... Black matrix pattern, 609 ... Second substrate, 610 ... External polarizing plate, 611 ... Built-in polarizing plate, 612 ... red color filter, 613 ... green color filter, 614 ... blue color filter, 615 ... red wavelength conversion layer, 616: Green wavelength conversion layer, 617: Blue wavelength conversion layer.

Claims (5)

In a transmissive liquid crystal display device that performs display by sandwiching a liquid crystal layer between a first substrate and a second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate.
A polarizing layer formed by uniaxially orienting a dichroic dye is provided on the side facing the liquid crystal layer of the second substrate, and externally polarized light is provided on the opposite side of the first substrate and the liquid crystal layer of the second substrate. With a plate,
A wavelength conversion layer containing a substance that absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more is provided on the upper surface of the polarizing layer of the second substrate with respect to light transmitted from the back surface of the first substrate. A liquid crystal display device. In a transmissive liquid crystal display device that performs display by sandwiching a liquid crystal layer between a first substrate and a second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate.
An external polarizing plate is provided on the opposite side of the liquid crystal layer of the first substrate and the second substrate,
A polarizing layer formed by orienting a dichroic dye in a uniaxial direction on the side facing the liquid crystal layer of the second substrate;
A color filter layer is provided on the upper surface of the polarizing layer of the second substrate,
A wavelength conversion layer containing a substance that absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more with respect to light transmitted from the back surface of the first substrate is provided on the upper surface of the color filter layer. Liquid crystal display device. In a transmissive liquid crystal display device that performs display by sandwiching a liquid crystal layer between a first substrate and a second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate.
An external polarizing plate is provided on the opposite side of the liquid crystal layer of the first substrate and the second substrate,
A polarizing layer formed by orienting a dichroic dye in a uniaxial direction on the side facing the liquid crystal layer of the second substrate;
A color filter layer is provided on the upper surface of the polarizing layer of the second substrate,
The color filter layer has a black matrix pattern and blue, green, and red pigment dispersion color patterns.
A liquid crystal display device having a wavelength conversion function including a substance that absorbs light in a visible light region and emits light in a longer wavelength region than the absorbed light in a pigment dispersion color filter. In a transmissive liquid crystal display device that performs display by sandwiching a liquid crystal layer between a first substrate and a second substrate facing each other, and light incident from the back surface of the first substrate is transmitted through the second substrate.
An external polarizing plate is provided on the opposite side of the liquid crystal layer of the first substrate and the second substrate,
A polarizing layer formed by orienting a dichroic dye in a uniaxial direction on the side facing the liquid crystal layer of the second substrate;
A color filter layer is provided on the upper surface of the polarizing layer of the second substrate,
The color filter layer has a black matrix pattern and blue, green, and red pigment dispersion color patterns.
A substance that absorbs light having a wavelength of 420 nm or less and emits light having a wavelength of 420 nm or more with respect to light transmitted from the back surface of the first substrate in the blue pattern,
A substance that emits light having a wavelength of 460 nm or less to light having a wavelength of 460 nm or less with respect to the light transmitted from the back surface of the first substrate in the green pattern,
A liquid crystal display device having a wavelength conversion function including a substance that emits light having a wavelength of 550 nm or less to light having a wavelength of 550 nm or less with respect to light transmitted from the back surface of the first substrate in the red pattern.   2. The polarizing axis of the polarizing layer and the polarizing axis of the polarizing plate on the second substrate are at the same angle and are orthogonal to the polarizing axis of the polarizing plate on the first substrate. 5. The liquid crystal display device according to 4.

Images