JP2014202864A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which the intensity of blue light emitted from a front surface of a liquid crystal display panel is suppressed.SOLUTION: A liquid crystal display device 20A includes a liquid crystal display panel 2 and a backlight assembly 10, and further, a resin layer 1 which is provided in the front surface of the liquid crystal display panel 2 and which is made of a transparent material obtained by mixing a prescribed amount of a colorant with a base resin comprising a photocurable resin curable with ultraviolet light or visible light or a transparent epoxy resin or the like. The resin layer 1 suppresses transmittance of light having a wavelength of 430 to 480 nm out of blue light (wavelength 380 to 495 nm) emitted from a white LED 9 being a backlight source, to 40 to 60%.

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a resin layer that reduces the transmittance of light of a specific range of wavelengths is formed on a part of a liquid crystal display panel.

  Conventionally, a cold cathode tube which is a fluorescent tube using a metal cathode has been used as a light source of a backlight which is a light source device of a liquid crystal display device. However, the cold cathode tube contains mercury in the fluorescent tube, so there is a concern about the adverse effect on the environment at the time of disposal, and in recent years, a white light emitting diode (hereinafter referred to as LED (Light Emitting Diode) with high luminous efficiency). (Hereinafter abbreviated as)), the replacement of cold-cathode tubes with white LEDs is progressing as a light source for backlights.

  Since white LEDs have low power consumption and do not require a high-voltage power supply, they were initially widely used in liquid crystal display devices for portable terminals such as mobile phones and tablet computers. In recent years, application to liquid crystal display devices for desktop personal computers and televisions has also been promoted.

  As a white LED, a blue LED is used as a light emitting element, and a pseudo white LED having a structure in which a phosphor that emits yellow fluorescence is arranged on the light emitting surface, or a blue LED is used as a light emitting element, and fluorescence that emits green and red fluorescence on the light emitting surface. There are high color rendering white LEDs with a structure in which the body is arranged, and RGB white LEDs using red, green and blue LED elements as one light source, but pseudo white LEDs are often used because of high luminous efficiency. ing.

  The backlight structure of the liquid crystal display device has an edge light system in which a line light source is arranged on the side of the display surface, and the light is converted into a surface light source with a light guide plate and a reflecting plate, and a plurality of light sources are arranged directly under the display surface. There is a direct type.

  Since liquid crystal display devices for portable terminals are highly demanded for thinning, the backlight is composed of a light source and several optical films such as a reflector and a light guide plate, making it easy to reduce the thickness. The method is heavily used. On the other hand, liquid crystal display devices for personal computer monitors and televisions are required to have high image quality and high contrast. Therefore, white LEDs are used in liquid crystal display panels to improve the contrast ratio by driving the backlight for each small area. A direct-type backlight system in which a plurality of direct-type backlights are arranged directly below is used.

  Although not related to a liquid crystal display device, Patent Document 1 (Japanese Patent Laid-Open No. 2007-93927) discloses sunglasses and anti-glare that have a function of cutting part of light having a wavelength of 380 to 500 nm out of visible light. An optical article such as glasses is disclosed.

JP 2007-93927 A

  As shown in FIG. 9, the pseudo-white LED described above exhibits spectral characteristics having peaks at a wavelength near 470 nm and a wavelength near 575 nm. Among these, light having a peak in the vicinity of a wavelength of 470 nm is a main peak of a blue LED which is a light emitting element.

  When the pseudo white LED is used as a backlight light source of a liquid crystal display device to display white, red (R), green (G), blue (B) provided on the viewer side of the liquid crystal display panel. ) Pass through the color filter substrate on which the three primary colors are arranged, peaks appear for each of the red, green, and blue wavelengths, exhibiting spectral characteristics as shown in FIG.

  As shown in FIG. 10, the light emitted from the blue LED, which is a light emitting element of the pseudo white LED, has a remarkably high luminance, and the light transmitted through the blue color filter (transmission wavelength 400) of the liquid crystal display panel shown in FIG. (˜550 nm) may be as high as about 80%, and even if it passes through the color filter substrate, it is hardly attenuated, and the display surface of the liquid crystal display panel has a wavelength of about 430 nm to about 470 nm. A range of light is observed at high intensity.

  The light emitted from the blue LED is light having a wavelength of 380 to 495 nm called so-called blue light. This blue light has the property closest to ultraviolet rays and has the property of reaching the retina without being absorbed by the cornea and lens of the eyeball. There are concerns about such problems.

  In addition, a human having a 24-hour biological rhythm is awakened by exposure to the blue light of the morning sun, and is brought to a dormant state by exposure to the orange light of dusk. For this reason, there is a concern that the biological rhythm is disturbed when exposed to light containing blue light at night and that fatigue remains in the daytime.

  Patent Document 1 described above proposes optical articles such as sunglasses and anti-glare glasses that protect eyes from blue light. However, the optical article of Patent Document 1 is intended only for eye protection, and cannot reduce the amount of exposure to blue light throughout the human body.

  An object of the present invention is to provide a liquid crystal display device capable of reducing the amount of light in a predetermined wavelength range out of light emitted from a backlight light source and transmitted through a liquid crystal display panel.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  In a liquid crystal display device which is a preferable embodiment of the present invention, a resin layer that suppresses transmission of light in a predetermined wavelength range out of light emitted from a backlight light source is provided in a part of the liquid crystal display panel.

  The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

  Of the light emitted from the backlight source of the liquid crystal display device and transmitted to the human body through the liquid crystal display panel, the amount of light in a predetermined wavelength range can be reduced.

FIG. 3 is a cross-sectional view illustrating a main part of the liquid crystal display device according to the first embodiment. It is a graph which shows the light transmittance of the resin layer in Embodiment 1,2. 4 is a graph showing spectral characteristics of light observed on the display surface of the liquid crystal display device of the first embodiment. 6 is a graph showing spectral characteristics of light observed on the display surface of the liquid crystal display device of the second embodiment. FIG. 10 is a main-portion cross-sectional view showing the liquid crystal display device of Embodiment 3. FIG. 6 is a main part sectional view showing a liquid crystal display device of a fourth embodiment. FIG. 10 is a cross-sectional view showing a main part of a liquid crystal display device according to a fifth embodiment. FIG. 10 is a cross-sectional view showing a main part of a liquid crystal display device according to a sixth embodiment. It is a graph which shows the spectral characteristic of pseudo white LED. It is a graph which shows the spectral characteristic of the light which permeate | transmitted the color filter board | substrate of a liquid crystal display panel. It is a graph which shows the spectral characteristic of the light which permeate | transmitted the blue color filter of a liquid crystal display panel.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted. In the embodiments, the description of the same or similar parts will not be repeated in principle unless particularly necessary.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a main part of the liquid crystal display device of the first embodiment. The liquid crystal display device 20A of the first embodiment is a liquid crystal display device for portable terminals that employs an edge light system, and suppresses transmission of light having a wavelength of 430 to 480 nm in order from the observer side (upper side in FIG. 1). The backlight assembly 10 includes a resin layer 1, a liquid crystal display panel 2, a white LED 9 as a backlight light source, and several optical films such as a reflector and a light guide plate.

  The liquid crystal display panel 2 includes a first polarizing plate 3, a first substrate 4 and a second substrate 5 made of a transparent insulating material such as glass, and a second polarizing plate 8. The first substrate 4 disposed on the front side of the liquid crystal display panel 2, that is, the viewer side, and the second substrate 5 disposed on the back side of the liquid crystal display panel 2 are attached to each other via a frame-shaped sealing material 6. The liquid crystal layer 7 sandwiched between the first substrate 4 and the second substrate 5 is disposed inside the sealing material 6. The sealing material 6 is disposed in a peripheral portion outside the display area of the liquid crystal display panel 2 so as to surround the liquid crystal layer 7.

  Although not shown, the liquid crystal layer 7 includes a pair of alignment films for aligning liquid crystal molecules in a certain direction and liquid crystal sealed between them. A color filter in which the three primary colors of red, green, and blue are arranged is attached to one surface of the first substrate 4 (the surface facing the liquid crystal layer 7), and one surface of the second substrate 5 (the liquid crystal layer). Thin film transistors (TFTs) for driving the liquid crystal layer 7 are formed in an array on the surface facing the surface 7.

  The white LED 9 that is a backlight light source employs a pseudo white LED having a high light emission efficiency having a structure in which a blue LED is used as a light emitting element and a phosphor that emits yellow fluorescence is disposed on the light emitting surface thereof.

  The resin layer 1 disposed on the front surface of the first substrate 4 is made of a transparent material in which a predetermined amount of a coloring material is mixed with a base resin made of a photocurable resin that is cured by ultraviolet rays or visible light, a transparent epoxy resin, or the like. Yes.

  As the base resin, it is desirable to select a base resin having a light transmittance (film thickness of 400 nm or more) after curing of 90% or more so as not to lower the light transmittance of the liquid crystal display panel 2. Examples of such a base resin include a photocurable resin composed of a monomer, a polymerization initiator, and a polymer for adjusting viscosity, such as a commercially available HRJ series (Kyoritsu Chemical Industry Co., Ltd.) and SVR1120 (Sony Chemical & Information Device Corporation). Alternatively, transparent epoxy resins that are used by mixing an epoxy resin and a modified alicyclic polyamine, such as Crystal Resin II and X-1745 (both are Nissin Resin Co., Ltd.) can be used.

  Examples of the colorant include N, N'-bis- (2-phenylethyl) perylene-3,4,9,10-bis- (dicarboximide) which is a perylene dye, and 1-phenylazo- which is an azo dye. 2-Naphthol-4 ', 6-disulphonic acid disodium (Sunset Yellow FCF, Wako Pure Chemical Industries, Ltd.), 4- (2-hydroxy-1-naphthylazo) benzenesulphonic acid sodium (Orange II, Daiwa Kasei Co., Ltd.) ) And the like.

  Each of the colorants is dissolved in ethyl alcohol at a predetermined concentration and mixed with the base resin. For example, when using photocurable resin SVR1120 as the base resin and N, N′-bis- (2-phenylethyl) perylene-3,4,9,10-bis- (dicarboximide) as the coloring material, a coloring material Is dissolved in ethyl alcohol so that the ratio is 0.1% by weight, and further mixed with the colorant solution so as to be 0.1% by weight with respect to the base resin. A resin material is prepared so that it may become 0.01 weight%.

  The resin material is applied to the surface of the first polarizing plate 3 disposed on the front side of the liquid crystal display panel 2 so as to be approximately equal to the size of the first polarizing plate 3. Examples of the coating method include dispenser coating, slot die coating coating, slit coater coating, screen printing, and spin coating.

  The coating thickness of the resin material does not significantly affect the spectral characteristics, but needs to be set according to the concentration of the colorant mixed in the base resin. For example, when using photocurable resin SVR1120 as the base resin and N, N′-bis- (2-phenylethyl) perylene-3, 4, 9, 10-bis- (dicarboximide) as the colorant, a resin material The coating thickness is desirably about 150 to 250 μm, and most desirably 200 μm.

  In order to cure the resin material applied to the surface of the first polarizing plate 3, for example, a sealed container (chamber) provided with an ultraviolet lamp is used. SVR-1120 which is the base resin of the resin layer 1 is difficult to be cured when oxygen is present during the photopolymerization reaction. Therefore, after replacing the inside of the sealed container with nitrogen gas, the resin layer 1 cured to the surface can be obtained by irradiating the resin material with ultraviolet rays.

  The solid line in the graph of FIG. 2 shows the light transmittance of the resin layer 1 obtained by applying 200 μm of the resin material to the surface of the first polarizing plate 3. As shown in the figure, the resin layer 1 had a light transmittance of 40 to 60% at a wavelength of 430 to 480 nm.

  3, when the resin layer 1 is provided on the front side of the liquid crystal display panel 2, the light intensity of 380 to 495 nm, which is the wavelength of blue light, is not provided with the resin layer 1 (FIG. 10). It was possible to suppress it to about ½ compared to (see).

  According to the liquid crystal display device 20A of the first embodiment in which the resin layer 1 is provided on the front side of the liquid crystal display panel 2, the display is slightly yellowish as compared with the case where the resin layer 1 is not provided. Since the blue light irradiated to the observer is suppressed, it is possible to realize a liquid crystal display device that is not only gentle on the eyes but also in consideration of biological rhythm.

(Embodiment 2)
The liquid crystal display device of the second embodiment has the same configuration as that of the first embodiment except that the concentration of the coloring material with respect to the base resin of the resin layer 1 of the first embodiment is 0.005% by weight. .

  The broken line in the graph of FIG. 2 indicates the light transmittance of the resin layer 1 of the second embodiment. As shown in the figure, this resin layer 1 had a light transmittance of 430 to 480 nm of 60 to 70%.

  Also, as shown in FIG. 4, by providing the resin layer 1 of the second embodiment on the front side of the liquid crystal display panel 2, the resin layer 1 is provided with light intensity of 380 to 495 nm which is the wavelength of blue light. It was possible to suppress to about 2/3 compared with the case where there was no (see FIG. 10).

  According to the liquid crystal display device of the second embodiment in which the resin layer 1 is provided on the front side of the liquid crystal display panel 2, the display is slightly yellowish compared to the case where the resin layer 1 is not provided. Since the blue light irradiated to the observer is suppressed, it is possible to realize a liquid crystal display device that is not only gentle on the eyes but also in consideration of biological rhythm.

(Embodiment 3)
FIG. 5 is a cross-sectional view of a main part of the liquid crystal display device of the third embodiment. The liquid crystal display device 20B according to the third embodiment is the same as the liquid crystal display device 2 except that the resin layer 1 according to the first embodiment is applied to the surface of the second polarizing plate 8 disposed on the back surface side of the liquid crystal display panel 2 with a slit coater. 1 has the same configuration.

(Embodiment 4)
FIG. 6 is a cross-sectional view of a main part of the liquid crystal display device according to the fourth embodiment. The liquid crystal display device 20C of the fourth embodiment has the same configuration as that of the first embodiment except that the installation location of the resin layer 1 is different.

  First, as in the first embodiment, a photocurable resin (SVR1120) is used as the base resin of the resin layer 1, and N, N′-bis- (2-phenylethyl) perylene-3, 4, 9, Using 10-bis- (dicarboximide), a resin material was prepared such that the colorant was 0.01 wt% with respect to the base resin.

Next, a slit coater is used so that this resin material is substantially equal to the size of the first substrate 4 on the surface (the surface on which the color filter is attached) of the first substrate 4 of the liquid crystal display panel 2 facing the liquid crystal layer 7. It was applied with. The coating thickness of the resin material was 200 μm. Then, the resin layer 1 was formed by irradiating an ultraviolet-ray and hardening a resin material. For the ultraviolet irradiation, an ultraviolet irradiation device using a high-pressure mercury lamp as a light source was used, and an integrated light amount of 5000 mJ / cm ² was irradiated.

  Next, an alignment film is applied to the surface of the first substrate 4 where the resin layer 1 is formed and the surface of the second substrate 5 facing the liquid crystal layer 7 (the surface where the thin film transistor is formed), respectively, at a predetermined angle. After rubbing in a direction that crosses each other, the first substrate 4 and the second substrate 5 are bonded to each other through the sealing material 6, and the liquid crystal is sealed in the gap between the first substrate 4 and the second substrate 5. Thus, the liquid crystal layer 7 was formed.

  Next, the first polarizing plate 3 is attached to the other surface of the first substrate 4 (the surface on the viewer side), and the second polarizing plate is applied to one surface of the second substrate 5 (the surface facing the backlight assembly 10). The liquid crystal display panel 2 was produced by affixing 8.

  Finally, the backlight assembly 10 having the same structure as that of the first embodiment is arranged on the back side of the liquid crystal display panel 2 to obtain the liquid crystal display device 20C of the fourth embodiment.

(Embodiment 5)
FIG. 7 is a cross-sectional view of a main part of the liquid crystal display device of the fifth embodiment. The liquid crystal display device 20D of the fifth embodiment has the same configuration as that of the first embodiment except that the installation location of the resin layer 1 is different.

  First, as in the first embodiment, a photocurable resin (SVR1120) is used as the base resin of the resin layer 1, and N, N′-bis- (2-phenylethyl) perylene-3, 4, 9, Using 10-bis- (dicarboximide), a resin material was prepared such that the colorant was 0.01 wt% with respect to the base resin.

  Next, this resin material is applied to the surface (surface on which the thin film transistor is formed) of the second substrate 5 of the liquid crystal display panel 2 facing the liquid crystal layer 7 with a slit coater so as to be approximately the same as the size of the second substrate 5. After application, the resin layer 1 was formed by curing the resin material in a sealed container equipped with an ultraviolet lamp. The coating thickness of the resin material was 200 μm.

  Next, the first polarizing plate 3 is attached to one surface (the surface on the observer side) of the first substrate 4, and the second polarizing plate is applied to the other surface (the surface facing the backlight assembly 10) of the second substrate 5. The liquid crystal display panel 2 was produced by affixing 8.

  Finally, the backlight assembly 10 having the same structure as that of the first embodiment is arranged on the back side of the liquid crystal display panel 2 to obtain the liquid crystal display device 20D of the fifth embodiment.

(Embodiment 6)
FIG. 8 is a cross-sectional view of a main part of the liquid crystal display device of the sixth embodiment. The liquid crystal display device 20E of the sixth embodiment has the same configuration as that of the first embodiment, except that a protective cover 11 made of a transparent resin film is attached to the surface of the resin layer 1 (the surface on the observer side). ing. By attaching the protective cover 11 to the surface of the resin layer 1, it is possible to suppress deterioration and damage of the resin layer 1 due to dust, moisture, physical impact, and the like.

  In the sixth embodiment, first, a resin material having the same composition as that of the first embodiment is applied to the surface of the protective cover 11 with a slit coater. The coating thickness of the resin material was 200 μm. Next, the front surface of the liquid crystal display panel 2 (the surface of the first polarizing plate 3) that has been assembled in advance and the surface on which the resin material of the protective cover 11 is applied are placed opposite to each other in a chamber having a predetermined degree of vacuum. Both were pasted together. Next, the resin layer 1 was formed between the liquid crystal display panel 2 and the protective cover 11 by irradiating ultraviolet rays from the outside of the protective cover 11 to cure the resin material.

  Finally, the backlight assembly 10 having the same structure as that of the first embodiment is disposed on the back side of the liquid crystal display panel 2 to obtain the liquid crystal display device 20E of the sixth embodiment.

  The liquid crystal display devices 20B to 20E of the above-described third to sixth embodiments have a slightly yellowish display as compared with the liquid crystal display device 20A of the first embodiment as compared with the case where the resin layer 1 is not provided. The blue light irradiated to the observer could be suppressed. As a result, it was possible to realize a liquid crystal display device that was not only gentle on the eyes but also considered biological rhythms.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  In the above-described embodiment, the case where the present invention is applied to a liquid crystal display device for portable terminals has been described. However, the present invention is not limited to this, and can be applied to a liquid crystal display device for desktop personal computers or televisions. .

  Moreover, white LED used for a backlight light source is not limited to pseudo white LED which uses blue LED as a light emitting element.

  The present invention can be applied to a liquid crystal display device using a white LED as a backlight light source.

DESCRIPTION OF SYMBOLS 1 Resin layer 2 Liquid crystal display panel 3 1st polarizing plate 4 1st board | substrate 5 2nd board | substrate 6 Sealing material 7 Liquid phase layer 8 2nd polarizing plate 9 White LED
10 Backlight assembly 11 Protective cover 20A, 20B, 20C, 20D, 20E Liquid crystal display device

Claims (10)

A first substrate disposed on the front surface side, a second substrate disposed on the back surface side, and between the first substrate and the second substrate; A liquid crystal display panel having a sandwiched liquid phase layer;
A backlight assembly disposed on the back side of the liquid crystal display panel and using a white light emitting diode as a light source;
A resin layer provided in a part of the liquid crystal display panel and suppressing transmission of light in a predetermined wavelength range;
A liquid crystal display device. The liquid crystal display device according to claim 1.
The white light emitting diode is a liquid crystal display device having a structure in which a blue light emitting diode is used as a light emitting element and a phosphor that emits yellow fluorescence is disposed on the light emitting surface thereof. The liquid crystal display device according to claim 1.
The light wavelength range is narrower than the wavelength range of light emitted from the white light emitting diode and transmitted through the blue color filter of the liquid crystal display panel. The liquid crystal display device according to claim 1.
The said resin layer is a liquid crystal display device whose transmittance of light with a wavelength of 430-480 nm is 40-70%. The liquid crystal display device according to claim 1.
The liquid crystal display device, wherein the resin layer is disposed on the front side of the first substrate. The liquid crystal display device according to claim 5.
A liquid crystal display device, wherein a protective cover is attached to a surface of the resin layer. The liquid crystal display device according to claim 1.
The liquid crystal display device, wherein the resin layer is disposed on the back side of the second substrate. The liquid crystal display device according to claim 1.
The liquid crystal display device, wherein the resin layer is disposed between the first substrate and the liquid phase layer. The liquid crystal display device according to claim 1.
The liquid crystal display device, wherein the resin layer is disposed between the second substrate and the liquid phase layer. The liquid crystal display device according to claim 1.
The resin layer includes a base resin made of a photocurable resin or a transparent epoxy resin, N, N′-bis- (2-phenylethyl) perylene-3, 4,9,10-bis- (dicarboximide), One or more dyes selected from the group consisting of 1-phenylazo-2-naphthol-4 ′, disodium 6-disulfonate, and sodium 4- (2-hydroxy-1-naphthylazo) benzenesulfonate were mixed. A liquid crystal display device made of a transparent material.

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