JP2008139832A - Liquid crystal display and optical element used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of suppressing deterioration in sensitivity to a remote controller caused by near-IR light emitted from a backlight, and to provide an optical element used for the display. <P>SOLUTION: The liquid crystal display 10A includes a liquid crystal display panel 11, a backlight unit 12 having a cold cathode tube, and an optical element (optical filter) 4A transmitting light in a visible region and partially absorbing light at wavelengths in an IR region. The optical filter 4A comprises a coloring material-containing resin layer 6 containing a near-IR light absorbing coloring material dye, and shows an average transmittance of 85% or more for light at wavelengths of 400 to 700 nm and an average transmittance of 85% or less for light at wavelengths of 850 to 1,150 nm. Thereby, reduction in sensitivity of peripheral devices and the display itself to remote controllers caused by IR light in the above wavelength range emitted from the backlight can be suppressed, while reduction in the display luminance is suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display capable of suppressing a decrease in sensitivity of a remote controller caused by infrared rays emitted from a liquid crystal display panel, and an optical element used therefor.

  There are several types of video display today, such as cathode ray tube displays, plasma displays, and liquid crystal displays. Almost all models of these video display displays are attached with a remote control device using near infrared communication, that is, a remote controller (hereinafter abbreviated as “remote controller”).

  FIG. 1 shows a signal wavelength of a general remote controller and a sensitivity curve of the light receiving portion. The remote control signal wavelength has one peak shape centered at 940 nm and having a full width at half maximum of about 50 nm. On the other hand, the light receiving part has sensitivity in a wide wavelength range of wavelengths from 850 nm to 1150 nm.

  In an environment where near-infrared light other than the remote control signal is mixed in the sensitivity wavelength region of the light receiving unit, the communication sensitivity of the remote control decreases, and the distance between the operable remote control and the communication device body decreases. In particular, plasma displays are known to emit a vast amount of near-infrared rays. This near-infrared rays not only cause a decrease in remote control sensitivity for the main body, but also infrared communication devices (for example, telephones) around the display. Such as a slave unit, an air conditioner, and an optical disk device such as a DVD player).

  On the other hand, it is known that a method of providing an optical filter containing a dye that absorbs light having a wavelength in the near-infrared region on the front side of the display is effective (for example, see Patent Document 1 below). Most current plasma displays use this type of optical filter.

JP 2005-272660 A Japanese Patent Laid-Open No. 55-21091

  By the way, as a thin television which is becoming mainstream recently in a large television, there is a liquid crystal display using a cold cathode tube as a backlight in addition to a plasma display. Although the amount of near infrared rays emitted from this cold cathode tube is smaller than that of a plasma display, the amount of generation tends to increase gradually with the recent increase in screen size. FIG. 2 shows an emission spectrum in the infrared wavelength region emitted from the cold cathode tube.

  As a method of cutting near infrared rays emitted from the backlight of a liquid crystal display, there is a method of providing an optical filter containing a pigment on the front surface of the display as in the case of a plasma display. However, a near infrared absorbing pigment has a light absorbing ability even in the visible region. Therefore, the display image usually has a luminance drop. The luminance reduction rate due to the dye film used in the plasma display is generally 20% or more.

  In the case of a liquid crystal display, since the amount of infrared rays generated is less than that of a plasma display, and the occurrence of failure due to this is not considered as a practical problem, the liquid crystal televisions currently on the market are provided with the dye film as described above. It is not done. For this reason, the current brightness of liquid crystal televisions is already accepted as a standard for general users, so if the brightness is reduced by providing the above dye, the decrease is compensated by some method and is almost equivalent to the current brightness. It is necessary to maintain the brightness.

  As a method for compensating the luminance of the backlight, there is a method of increasing the tube current of the cold cathode tube and increasing the illuminance. However, as the tube current is increased, the temperature in the tube rises, so that the light emission efficiency is lowered, and there is a limit to the improvement in illuminance. Generally, the limit of illuminance correction by the tube current of a cold cathode tube currently used for a backlight is about 10%.

  On the other hand, as a method of cutting near infrared rays, there is a method of using light selective reflection by an optical multilayer film in addition to using an optical filter containing a dye (see, for example, Patent Document 2). In the case of a multilayer film, it is possible to increase the transmittance in the visible region depending on the film design, which is more advantageous than the dye film in terms of luminance, but there are many manufacturing processes and high film thickness accuracy for each layer. In most cases, the manufacturing cost is much higher than that of the dye film.

  The present invention has been made in view of the above problems, and a liquid crystal display capable of suppressing a decrease in luminance while suppressing a decrease in remote control sensitivity of peripheral devices and the display itself caused by near infrared rays emitted from the liquid crystal display, and to the same It is an object to provide an optical element to be used.

  In solving the above problems, the liquid crystal display of the present invention includes an optical element having a function of cutting a part of infrared rays generated from a cold cathode tube. This optical element contains a dye having absorption in the near infrared wavelength region generated from a cold cathode tube, and is applied to a visible region by applying an antireflection layer or integrating with another optical film used for a liquid crystal display. Therefore, a luminance reduction rate of 10% or less can be realized. Specific features are as follows.

  The optical element according to the present invention includes a dye that absorbs more light in the near-infrared region than light in the visible region, and the transmittance characteristic has an average transmittance value of 85% or more for light having a wavelength of 400 nm to 700 nm. In addition, the average transmittance of light having a wavelength of 850 nm to 1150 nm is 85% or less. When the average transmittance of light in the wavelength region of 400 nm to 700 nm is lower than 85%, the display luminance reduction rate is higher than 10% that can be corrected by the tube current of the cold cathode tube. Further, when the average transmittance of light in the wavelength region of 850 nm or more and 1150 nm or less is higher than 85%, remote control operation failure due to infrared rays can hardly be suppressed.

  The optical element according to the present invention can be produced by applying a binder resin composition containing a near-infrared absorbing dye on a substrate, and is easy to produce compared to the case of constituting an optical multilayer film. This is also advantageous in terms of cost. The dye can be selected from the group consisting of ammonium salts, aminium salts, iminium salts, diiminium salts, diimmonium salts, quinones, phthalocyanines, naphthalocyanines, cyanines, metal complexes, and mixtures thereof. The binder resin is selected from polyester resins, acrylic resins, cellulose resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, phenol resins, polyamide resins, polyurethane resins, polyolefin resins, or polycarbonate resins. Is done.

  In addition, after the resin layer is applied to the base material, the surface reflectance can be reduced by applying a substance having a lower refractive index than the resin layer to a predetermined thickness, thereby further suppressing the decrease in luminance of the display. It is possible. Since surface reflection occurs on the incident surface side and the opposite surface side when the substrate is transparent, it is desirable that this antireflection film is applied to both surfaces of the substrate.

  This optical element may be provided integrally with an optical film such as a diffusion sheet, a prism sheet, or a reflective polarization separation element disposed between the liquid crystal display panel and the backlight unit. In this case, when the pigment-containing resin layer is directly applied to the optical film, or when the film coated with the pigment-containing resin layer is bonded via the optical film and the adhesive layer, the bonding surface side is air. Since there is no contact, there is no need to consider the surface reflection. Therefore, in this case, the antireflection layer only needs to be applied on one side of the external air side, which is advantageous in terms of manufacturing cost.

  Some dyes used in this optical element are susceptible to decomposition by UV (ultraviolet) irradiation, and the transmission characteristics of this optical element gradually deteriorate due to the UV generated from the cold cathode tube, which adversely affects the image on the display. May affect. Particularly, when the installation position of the optical element is directly above the cold cathode tube, UV from the cold cathode tube is directly irradiated onto the optical element, and the above phenomenon is likely to occur. In such a case, the change in the transmission characteristics can be suppressed by providing a layer having a UV absorbing action between the optical element and the backlight. Specifically, this layer is preferably an ultraviolet absorption layer having an absorption band in a wavelength region of 200 nm or more and 380 nm or less and having a transmittance of 5% or less in the wavelength region.

  In addition to being installed between the liquid crystal display panel and the backlight, the present optical element can also be installed integrally with the liquid crystal display panel. For example, an optical element can be provided on the front side or the back side of the liquid crystal display panel. In this case, the present optical element can be installed on the inner surface side of the antireflection layer (AR film) or hard coat layer disposed on the front side of the liquid crystal display panel. Further, when these antireflection layer and hard coat layer are bonded to the liquid crystal display panel via an adhesive layer, the optical element is constituted by containing this adhesive layer containing a near infrared absorbing dye. It may be. Further, when the optical element is disposed on the front side of the liquid crystal display panel, the dye may be deteriorated by ultraviolet rays contained in external light such as sunlight. Therefore, there is an ultraviolet absorbing layer on the outer surface side of the optical element. It is preferable to be provided.

  As described above, according to the present invention, it is possible to suppress a decrease in remote control sensitivity of peripheral devices and the display itself caused by infrared rays emitted from the backlight while suppressing a decrease in display luminance.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 3 is a schematic cross-sectional view showing the configuration of the liquid crystal display 10A according to the first embodiment of the present invention. The illustrated liquid crystal display 10A is configured for a large liquid crystal television, for example, and includes a liquid crystal display panel 11 and a backlight unit 12 disposed on the back side (lower side in FIG. 3) of the liquid crystal display panel 11. Yes. Between the liquid crystal display panel 11 and the backlight unit 12, a diffusion plate 13, a diffusion sheet 14, a prism sheet 15, an optical filter 4 </ b> A, a polarization separation element 16, and the like are appropriately combined.

  The backlight unit 12, the diffusion plate 13, the diffusion sheet 14, the prism sheet 15, the optical filter 4 </ b> A, and the polarization separation element 16 constitute a backlight device that irradiates the liquid crystal display panel 11 with illumination light. .

  The optical filter 4A is configured as an “optical element” according to the present invention. As described later, the optical filter 4A transmits light in the visible region irradiated from the backlight unit 12, and a part of the wavelength in the infrared region. It has a function to absorb.

  The liquid crystal display panel 11 includes a pair of transparent substrates 2a and 2b that are opposed to each other with the liquid crystal layer 1 interposed therebetween, and a pair of polarizing plates 3a and 3b that are respectively disposed on the outer surface sides of the transparent substrates 2a and 2b. . The polarizing plates 3a and 3b are, for example, iodine-based polarizing plates, and are configured by adhering a TAC (triacetyl cellulose) film to a PVA (polyvinyl alcohol) film that is adsorbed with iodine ions and uniaxially stretched. In addition, you may interpose optical compensation films, such as a phase difference plate, between transparent substrate 2a, 2b and polarizing plate 3a, 3b as needed.

  The configuration of the liquid crystal layer 1 is not particularly limited, and is a liquid crystal material in which the dielectric anisotropy is positive and the molecular long axis is substantially parallel to the electric field direction when an electric field is applied, or the molecular long axis is negative when the dielectric anisotropy is negative and the electric field is applied. A vertical alignment type liquid crystal material or the like substantially perpendicular to the electric field direction is used.

  With reference to FIG. 3, the light (backlight) emitted from the backlight unit 12 passes to the liquid crystal display panel 11 via the diffusion plate 13, the diffusion sheet 14, the prism sheet 15, the optical filter 4 </ b> A, and the polarization separation element 16. Incident.

  The diffusing plate 13 scatters and emits incident backlight light, and serves to make the bright line of the backlight unit 12 invisible from the front surface of the liquid crystal display panel 11. The diffusion sheet 14 diffuses and emits backlight light within a predetermined angle range. The prism sheet 15 condenses the backlight light diffused by the diffusion sheet 14 and makes it incident on the optical filter 4A. The optical filter 4A transmits the backlight region in the visible region, while limiting a transmission amount by absorbing a part of the wavelength in the infrared region.

  The polarization separation element 16 is a reflective polarization separation element that transmits a certain linearly polarized light component included in incident light and reflects other linearly polarized light components. Thereby, only polarized light in a certain direction is incident on the liquid crystal display panel 11. The polarized light emitted from the polarization separation element 16 enters the liquid crystal layer 1 through the polarizing plate 3b having a transmission axis parallel to the polarization direction. The liquid crystal molecules constituting the liquid crystal layer 1 are subjected to voltage control for each pixel region sandwiched between the transparent electrodes, thereby controlling the orientation of the incident polarized light. As a result, light that passes through the color filter and passes through the polarizing plate 3 a on the front side of the liquid crystal display panel 11 and light that does not pass through are controlled for each pixel, and a color image is formed on the front side of the liquid crystal display panel 11.

  The backlight unit 12 is composed of a direct type backlight unit that irradiates illumination light from the back side of the liquid crystal display panel 11, and includes a linear light source 8 composed of a plurality of cold cathode fluorescent lamps (CCFLs), The light source 8 is composed of a reflector 9 that covers the back side and the side of the light source 8.

  In general, Ar (argon) gas and Hg (mercury) are enclosed in a cold cathode tube constituting the light source 8. For this reason, in the case of a liquid crystal display using a cold cathode tube as a backlight, as shown in FIG. 2, there are three Ar-derived emission line peaks at 912 nm, 922 nm and 965 nm, and an Hg-induced emission line peak at 1013 nm. Near-infrared radiation with The three bright lines due to Ar are generated in a large amount immediately after turning on the TV and decrease with time. On the contrary, the bright line peak due to Hg increases as the temperature inside the cold cathode tube increases and the amount of Hg vapor increases.

  Accordingly, the near infrared ray emitted from the liquid crystal display 10A is a remote control light receiving unit of the liquid crystal display 10A itself or a remote control light receiving unit of another peripheral device (for example, an optical device such as a handset of a telephone, an air conditioner, or a DVD player). The liquid crystal display is caused by the near infrared rays emitted from the liquid crystal display 10A because it is likely to be reflected by indoor walls, furniture, user clothes, etc. There is a possibility that the remote control sensitivity of 10A and other peripheral devices is lowered.

  Therefore, in the present embodiment, in order to suppress the deterioration of the remote control sensitivity of the peripheral device and the liquid crystal display 10A itself caused by the near infrared rays radiated from the liquid crystal display 10A, the liquid crystal display panel 11 and the backlight unit 12 are not affected. The optical filter 4A according to the present invention is arranged in the above.

  FIG. 4A is a cross-sectional view showing an example of the configuration of the optical filter 4A. The optical filter 4A is coated (coating) on a transparent substrate 5 made of, for example, a transparent plastic film or glass having a transmittance of 90% or more, and a near-infrared absorbing pigment dispersed in a binder resin. ) Is configured. Several dyes may be mixed in one layer, or this dye-containing resin layer may be provided on both sides of the substrate. The optical filter 4 </ b> A has a function of transmitting light in the visible region and attenuating the transmission amount by absorbing part of the light in the infrared region.

  The constituent material of the transparent substrate 5 is not particularly limited, but is polyester, acrylic, cellulose, polyethylene, polypropylene, polyolefin, polyvinyl chloride, triacetylcellulose, polycarbonate, phenol. And a transparent film formed from a urethane-based resin or the like. As the polyester film, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate or a biaxially oriented polyester film formed from a copolymer mainly composed of these resin components is preferable. The formed biaxially oriented polyethylene terephthalate film is particularly preferable. The transparent substrate 5 may contain various additives as necessary within a range not impairing the effects of the present invention. Examples of the additive include an antistatic agent, a UV (ultraviolet) absorber, and a stabilizer. Moreover, it is preferable that the said polyester film does not contain substantially the inert particle | grains aiming at the handleability (slidability, winding property, blocking resistance, etc.) of a film from a transparency point.

  In order to improve the adhesion between the transparent substrate 5 and the dye-containing resin layer 6, it is preferable to laminate an easy-adhesion layer on at least one surface of the transparent substrate 5. Moreover, slipping property, winding property, and scratch resistance can be imparted by containing fine particles having an appropriate particle size in the easy adhesion layer and forming fine irregularities on the film surface. For this reason, it is not necessary to contain fine particles in the transparent support, and high transparency with a total light transmittance of 89% or more can be maintained. Examples of the resin material constituting the easy-adhesion layer include copolymer polyester resins, polyurethane resins, acrylic resins, acrylic graft polyester resins, styrene / maleic acid graft polyester resins, and the like. It is preferable.

  On the other hand, in the dye-containing resin layer 6, the glass transition temperature of the binder resin in which the near-infrared absorbing dye is dispersed is equal to or higher than the guaranteed use temperature of the device using the optical filter 4A from the viewpoint of dye stability. preferable. The specific range of the glass transition temperature of the binder resin is preferably 85 ° C. or higher and 150 ° C. or lower, particularly preferably 90 ° C. or higher and 140 ° C. or lower. Note that the dye-containing resin layer 6 may be directly formed on an optical film such as the diffusion plate 13, the diffusion sheet 14, the prism sheet 15, or the polarization separation element 16 constituting the liquid crystal display 10 </ b> A described above. Also in this case, it goes without saying that the above-mentioned contents are suitable.

  The polymer resin material constituting the binder resin is not particularly limited, and examples thereof include polyester-based, acrylic-based, cellulose-based, polyethylene-based, polypropylene-based, polyolefin-based, polyvinyl chloride-based, polycarbonate, phenol-based, and urethane-based resins. An acrylic resin is preferable from the viewpoints of dispersion stability and environmental load.

  Moreover, the material which comprises the near-infrared absorption pigment | dye which comprises the pigment | dye containing resin layer 6 is not specifically limited, For example, ammonium salt, aminium salt, iminium salt, diiminium salt, diimonium salt, quinone, phthalocyanine, naphthalocyanine, cyanine, A metal complex or a mixture thereof is preferred.

  Incidentally, light reflection naturally occurs at the interface between the surface of the transparent substrate 5 and the surface of the dye-containing resin layer 6 and air. Generally, since the refractive index of transparent plastic is about 1.45 to 1.65, the surface reflection amount is about 5%. In the case of the optical filter 4A having the configuration shown in FIG. 4A, surface reflection occurs on both the surface of the dye-containing resin layer 6 and the surface of the transparent substrate 5 on the opposite side. 10% will be reflected. This surface reflection also increases the loss of backlight light and decreases the display brightness by several percent.

  In order to suppress this, as shown in FIG. 4B, there is a method of applying antireflection films 7 a and 7 b made of low refractive index films on the surface of the dye-containing resin layer 6 and the surface of the transparent substrate 5. The antireflection films 7a and 7b can be made of fluorine resin or the like. FIG. 5 shows a spectral transmittance curve when a fluororesin having a refractive index of 1.35 as an antireflection layer is applied to both sides of a polyethylene terephthalate film by about 100 nm. By forming the antireflection layer, 10% of the surface reflection in the absence of the antireflection layer can be reduced to about 2%. The antireflection layers 7a and 7b may be formed of a laminated film composed of a combination of a high refractive index film and a low refractive index film.

  The transmittance of the dye-containing resin layer 6 can be adjusted by the film thickness or the dye concentration with respect to the resin layer. Specifically, the optical filter 4A has an average transmittance of 85% or more for visible light having a wavelength of 400 nm or more and 700 nm or less. Further, the average transmittance of light having a wavelength of 850 nm or more and 1150 nm or less is configured to be 85% or less, and preferably, the wavelength has a minimum transmittance. The wavelength range of 850 nm to 1150 nm corresponds to the light receiving sensitivity region of a general remote control signal light receiving unit.

  Furthermore, the optical filter 4A is configured such that the reduction rate of the display brightness of the liquid crystal display when the optical filter 4A is provided is 10% or less with respect to the display brightness of the liquid crystal display when the optical filter 4A is not provided. For this reason, it is possible to compensate for this luminance reduction by adjusting the output of the backlight, and to completely eliminate the luminance reduction.

  By the way, in the optical filter 4A according to the present invention, depending on the material of the near-infrared absorbing pigment, the near-infrared absorption characteristics may change due to the ultraviolet rays from the outside. This is because there are dyes whose absorption characteristics are easily changed by ultraviolet rays generated from the CCFL backlight. In general, the polarization separation element provided in the liquid crystal display panel contains a UV absorber. However, as shown in FIG. 3, the optical filter 4A according to the present invention is installed on the backlight side with respect to the polarization separation element 16. If so, ultraviolet light from the backlight becomes a problem.

  In this case, a method of providing a UV absorption layer different from the polarization separation element on the side irradiated with ultraviolet rays is effective. For example, a resin layer containing a UV absorber may be applied to the surface of the dye-containing resin layer 6, and a resin layer containing a UV absorber is applied on the transparent substrate 5 that supports the dye-containing resin layer 6. You may provide separately. Further, a transparent substrate 5 containing a UV absorber may be used as the ultraviolet absorbing layer. The ultraviolet absorbing layer preferably has an absorption band in a wavelength region of 200 nm or more and 380 nm or less, and the transmittance in the wavelength region is preferably 5% or less.

  FIG. 6 shows an example of the spectral transmittance curve of the optical filter 4A. The optical filter 4A in the illustrated example has a low transmittance at a wavelength of 850 nm to 1150 nm at which the remote control light-receiving unit has sensitivity. Therefore, the near-infrared ray in this wavelength region generated from the backlight unit 12 is internally reflected, and the display The amount emitted to the outside can be reduced.

  In particular, in the case of a liquid crystal display having a cold cathode tube as a backlight, near infrared rays generated at wavelengths of 850 nm to 1150 nm are three Ar-derived bright line peaks at 912 nm, 922 nm, and 965 nm as shown in FIG. It is a bright line peak due to Hg at 1013 nm. By providing this optical filter 4A, the amount of near-infrared radiation can be reduced. Thereby, the fall of the peripheral device and the remote control sensitivity of display itself which originate in the infrared rays radiated | emitted from 10 A of liquid crystal displays can be suppressed.

  On the other hand, since the optical filter 4A having the optical characteristics of FIG. 6 has a high light transmittance in the visible region, the influence on the quality of the display image, particularly the luminance, can be reduced.

  The near-infrared transmittance of the optical filter 4A is desirably changed according to the screen size of the target display. That is, the larger the screen size, the greater the amount of near infrared rays that are generated, so the transmittance of the optical filter 4A needs to be lowered accordingly. Further, the transmittance of the optical filter 4A in the visible region is related to the luminance of the image displayed on the display, and the luminance decreases as the transmittance decreases. When it is necessary to reduce the luminance reduction amount of the image by providing the optical filter 4A inside the display to 10% or less, the average transmittance of the optical filter 4A in the visible region wavelength of 400 to 700 nm is at least 85% or more. There is a need.

  In the liquid crystal display 10 </ b> A of the present embodiment, an optical filter 4 </ b> A that attenuates the amount of infrared light transmitted in the predetermined wavelength region emitted from the backlight unit 12 is disposed between the liquid crystal display panel 11 and the backlight unit 12. Therefore, compared with the case where the optical filter 4A is installed on the front surface side of the liquid crystal display panel 11, it is possible to prevent deterioration of image quality due to reflection of external light.

  Further, since the optical filter 4A is disposed between the polarization separation element 16 and the backlight unit 12, it is possible to prevent the polarization-separated light from becoming non-polarized and to improve the light use efficiency and the luminance. Can be achieved.

(Second Embodiment)
FIG. 7 is a schematic cross-sectional view showing a configuration of a liquid crystal display 10B according to the second embodiment of the present invention. In the figure, portions corresponding to those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The liquid crystal display 10B of the present embodiment is different from the first embodiment described above in that an optical filter 4B having the same function as the optical filter 4A having the above-described configuration is integrated with the prism sheet 15. By integrating the optical filter 4B with the prism sheet 15, the number of parts can be reduced and the assembly workability can be improved. And shape retainability can be improved.

  8 and 9 show specific examples of the configuration of the optical filter 4B integrated with the optical film. The optical filter 4B shown in FIG. 8A shows an example in which the pigment-containing resin layer 6 is directly applied (coated) to the flat surface opposite to the prism surface of the prism sheet 15. According to this configuration, there is an advantage that a support for the dye-containing resin layer 6 is not required, and a low-cost and simple structure can be achieved.

  Further, as shown in FIG. 8B, an optical filter 4B may be obtained by bonding the optical filter 4A described in the first embodiment to the flat surface of the prism sheet 15 via the adhesive layer 20. In this case, since the surface side of the transparent substrate 5 serves as an adhesive surface with the prism sheet 15, it is possible to eliminate the surface reflection of light on the surface side of the transparent substrate 5 and reduce the amount of decrease in luminance. Furthermore, the transparent base material 5 functions as a reinforcing material for the prism sheet 15, and shape changes such as wrinkling and twisting of the prism sheet 15 can be suppressed. FIG. 8C is a configuration example in which the antireflection film 7a is formed on the surface of the dye-containing resin layer 6 in the configuration shown in FIG. 8B, and the luminance reduction amount is further reduced.

  FIG. 9A shows an example in which the installation of the transparent substrate 5 is abolished from the configuration shown in FIG. 8C. In this case, a release film is used as a support for the dye-containing resin layer 6, and the dye-containing resin layer 6 is attached to the adhesive layer 20. The optical filter 4B shown in figure can be comprised by forming the antireflection film 7a on the surface of the pigment | dye containing resin layer 6 after peeling film removal. Since the transmittance of the optical filter 4B can be increased by eliminating the transparent base material 5, it is possible to reduce the amount of decrease in luminance. In addition, you may make it comprise a near-infrared absorption pigment | dye in the adhesion layer 20, and comprise this as an optical filter of this invention.

  FIG. 9B shows an example in which the optical filter 4B is configured by coating the dye-containing resin layer 6 on the surface of the polarization separation element 16 on the backlight unit side. This indicates that the optical film integrated with the optical filter 4B is not limited to the prism sheet 15. Therefore, the optical filter 4B can be integrally formed on the diffusion sheet 14 or the diffusion plate 13.

  Furthermore, depending on the installation location of the optical filter 4B, it is preferable to use a substrate having a small birefringence in order not to affect the light whose polarization is controlled by the polarization separation element. For example, triacetyl cellulose (TAC), cycloolefin polymer, and norbornene-based resin can be used. As the installation location of the dye film, a TAC film provided in the polarizing plate 3b installed on the back side (light incident surface side) of the liquid crystal display panel 11 as shown in FIG. Compared with the case where the optical filter 4B is installed on the backlight side of the polarization separation element 16 in order to target the light whose polarization is controlled by the polarization separation element 16, there is less repetitive reflection, and the amount of decrease in luminance and chromaticity. The deviation is small. In addition, the said pigment | dye film | membrane may be directly apply | coated to the low birefringence board | substrate represented by the TAC film, or may be bonded through an adhesion layer.

(Third embodiment)
FIG. 10 is a schematic cross-sectional view showing a configuration of a liquid crystal display 10C according to the third embodiment of the present invention. In the figure, portions corresponding to those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The liquid crystal display 10C of the present embodiment has the above-described first configuration in that the optical filter 4C having the same function as the optical filter 4A having the above-described configuration is installed on the outer surface side (front surface or front surface side) of the liquid crystal display panel 11. This is different from the first embodiment.

  FIG. 11A shows a specific example of the configuration of the optical filter 4 </ b> C integrated with the liquid crystal display panel 11. The optical filter 4 </ b> C is installed between the front transparent substrate 2 a constituting the liquid crystal display panel 11 and the front polarizing plate 3 a, and is a polarization in which the dye-containing resin layer 6 is applied and formed via the adhesive layer 20. The plate 3a is formed by sticking to the transparent substrate 2a. Thus, by installing the optical filter 4 </ b> C on the outer surface side of the liquid crystal display panel 11, the same effect as in the first embodiment can be obtained.

  FIG. 11B shows an example in which the optical filter 4C is arranged on the inner surface side of the AR (antireflection) film 21 and the hard coat layer 22 arranged on the outermost surface of the liquid crystal display panel. The AR film 21 is for preventing deterioration of image quality due to reflection of external light. The hard coat layer 22 is for protecting the panel from an external impact or load, and has a relatively hard or elastic property such as a melanin resin, an alkyd resin, an acrylic resin, a silicon resin, or a urethane resin. It is made of resin material. The optical filter 4C can be configured, for example, by applying the dye-containing resin film 6 to the inner surface side of the support base material 23 that supports the hard coat layer 22.

  Further, FIG. 11C uses a dye-containing pressure-sensitive adhesive resin layer 24 in which a near-infrared absorbing dye is contained in a pressure-sensitive adhesive for bonding between the support substrate 23 of the hard coat layer 22 and the polarizing plate 3a. An example configured as 4C is shown. By providing the adhesive layer with an infrared absorbing function, the manufacturing cost can be further reduced.

  In addition, by disposing the optical filter 4C on the outer surface side of the liquid crystal display panel 11, the absorption characteristics of the near-infrared absorbing pigment may be changed by ultraviolet rays contained in external light such as sunlight. Accordingly, it is a preferred embodiment to provide an ultraviolet absorbing layer on the outer surface side of the optical filter 4C. The ultraviolet absorbing layer can be separately formed on the outer surface side of the optical filter 4C, or, for example, a UV absorber can be added to the support base 23 of the hard coat layer 22 to form an ultraviolet absorbing layer. The ultraviolet absorbing layer preferably has an absorption band in a wavelength region of 200 nm to 380 nm and has a transmittance of 5% or less in that wavelength region.

[Fourth and fifth embodiments]
By the way, in general, various optical films such as a diffusion sheet and a prism sheet are used together in the liquid crystal display, and these optical films are placed in an overlapping manner between the liquid crystal display panel and the backlight unit. At the outermost surface portion of each optical film, surface reflection occurs according to the difference between the refractive index of the material and the refractive index of air. Generally, the refractive index of a substance becomes larger at the shorter wavelength side. The surface reflection of the film increases as the wavelength becomes shorter. Of the light emitted from the backlight unit, the wavelength of visible light is shorter than that of near-infrared light, so that the ratio of reflected light on the surface of each optical film is higher for visible light. The ratio also increases.

  The dye constituting the optical element (optical filter) according to the present invention has an absorption maximum in the near-infrared region, but has some light absorption in the visible region, and thus has a large number of multiple reflections. When installed at a position, the influence of luminance and chromaticity change tends to be greater than the effect of increasing the amount of absorption of near infrared rays. Therefore, it is desirable that the optical element according to the present invention be installed at a position where the number of reflections is as small as possible. Between the backlight unit and the liquid crystal display panel in the liquid crystal display, the multiple reflection amount of the backlight light is reduced as the installation position is closer to the liquid crystal display panel side, so this optical filter is located closer to the liquid crystal display panel or the liquid crystal display panel. When provided integrally with the display panel, the amount of change in luminance and chromaticity associated with near-infrared absorption can be reduced.

  Furthermore, when a reflective polarization separation element is provided in the liquid crystal display, if the optical element according to the present invention is installed on the liquid crystal display panel side of the polarization separation element, the luminance change and the chromaticity change are caused more than other installation positions. Suppressing near-infrared cut may be possible. This is because the polarization separation element for the purpose of improving luminance is designed not to maintain the polarization separation function up to the near infrared region. When the optical element of the present invention is installed on the backlight unit side of the polarization separation element, light in the visible wavelength region passes through the optical element due to reflection by the polarization separation element, and the number of times of light absorption increases. Since infrared rays are transmitted without being reflected by the polarization separation element, the number of times of passing through the optical element is almost once. On the other hand, when this optical element is installed closer to the liquid crystal display panel than the polarization separation element, the number of times visible light and near infrared light pass through the optical element is approximately one for both. Therefore, when compared with the same near-infrared cut amount, the latter case can reduce the decrease in luminance and chromaticity.

  However, when this optical element is installed between a reflective polarization separation element and a liquid crystal display panel, if a material having a high birefringence, such as polyethylene terephthalate, is used for the coating substrate of this optical element, the polarization separation element will pass. Since the polarization direction of the emitted light is disturbed, the brightness rapidly decreases. In order to prevent this decrease in luminance, the dye-containing resin layer constituting the optical element of the present invention is directly applied to the optical film disposed within the installation position of the optical element, or without using a substrate. There is a method in which a dye-containing resin film is prepared and provided integrally with a liquid crystal display panel or a polarization separation element via an adhesive film or the like. In addition, when a material coated with a pigment-containing resin layer using a base material is provided at that position, the brightness reduction is minimized by using a low birefringence material such as triacetyl cellulose or a polycarbonate film for the base material. It can be suppressed to the limit.

  Based on the above, the fourth and fifth embodiments of the present invention will be described below.

(Fourth embodiment)
FIG. 12 is a schematic cross-sectional view showing a configuration of a liquid crystal display 10D according to the fourth embodiment of the present invention. In the figure, portions corresponding to those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the liquid crystal display 10D of the present embodiment, an optical filter 4D having the same function as the optical filter 4A having the above-described configuration is installed on the back side of the liquid crystal display panel 11 (the surface on the backlight unit 12 side).

  The optical filter 4D of the present embodiment does not use the transparent substrate 5 like the optical filter 4A shown in FIG. 4A, and the dye-containing resin layer 6 is directly applied to the back surface of the liquid crystal display panel 11, or It is installed through an adhesive layer. The installation position of the optical filter 4D is not limited to only the outermost surface on the panel rear side, and may be provided between the polarizing plate 3b and the transparent substrate 2b. Further, when the polarization separation element 16 is integrally laminated on the liquid crystal display panel, the optical filter 4D may be provided on the panel side surface of the polarization separation element 16.

  In the present embodiment, the polarization separation element 16 is provided on the backlight unit 12 side of the optical filter 4D. However, since the optical filter 4D does not use a base material that disturbs polarization, the luminance decreases due to depolarization. There is an advantage that does not occur. Further, since the optical filter 4D is provided integrally with the liquid crystal display panel 11, the surface reflection amount by the optical filter itself can be replaced with the reflection amount of the panel surface when the optical filter is not installed. It is also possible to suppress a decrease in luminance due to.

  13A to 13E schematically show a specific example of a method of installing the optical filter 4D on the back surface of the liquid crystal display panel 11 via an adhesive layer. First, the pigment-containing resin layer 6 containing a near-infrared absorbing pigment is coated on the easily peelable film 25 and dried (FIG. 13A). Next, the pressure-sensitive adhesive layer 20 having one surface supported by the easily peelable film 26 is laminated and bonded to the dye-containing resin layer 6 (FIG. 13B). Next, the easily peelable film 26 is peeled from the adhesive layer 20 (FIG. 13C), and the adhesive layer 20 is adhered to the back side of the liquid crystal display panel 11 (FIG. 13D). Finally, the optical filter 4D is formed on the back side of the liquid crystal display panel 11 by peeling the easily peelable film 25 from the dye-containing resin layer 6 (FIG. 13E).

(Fifth embodiment)
FIG. 14 is a schematic cross-sectional view showing a configuration of a liquid crystal display 10E according to the fifth embodiment of the present invention. In the figure, portions corresponding to those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the liquid crystal display 10E of the present embodiment, the optical filter 4E of the present invention that absorbs near-infrared light is installed between the liquid crystal display panel 11 and the polarization separation element 16. As shown in FIG. 4C, the optical filter 4E is obtained by coating a pigment-containing resin layer 6 on a transparent substrate 5E. The transparent substrate 5E is made of a compound such as triacetyl cellulose or polycarbonate film. It is made of a material with low refraction. Thereby, since the polarization | polarized-light passes through the optical filter 4E without disturbing the polarization direction of the polarized light which permeate | transmitted the polarization separation element 16, the fall of a brightness | luminance can be suppressed.

  In the present embodiment, the optical filter 4E may be integrally provided on the surface of the liquid crystal display panel 11 or the polarization separation element 16 via an adhesive layer or the like, as in the fourth embodiment. In this case, since the coating process of the dye-containing resin can be performed independently of the liquid crystal display panel 11 and the polarization separation element 16, there is an advantage that it is relatively easy to manufacture.

  Examples of the present invention will be described below. In addition, the following Examples are illustrations and this invention is not limited to these Examples.

(Example 1)
A sample of an optical filter as an optical element according to the present invention was produced by the following procedure.

[Coating composition]
First, a paint for the dye-containing resin layer was prepared. The materials used are shown below.
Near-infrared absorbing dye: diimmonium salt (“CIR-1085” manufactured by Nippon Carlit Co., Ltd.)
Antioxidant: Phosphite-based antioxidant (Adeka Stub 1178 manufactured by Asahi Denka Kogyo Co., Ltd.)
・ Coating substrate: Highly transparent polyester film substrate (“COSMO Shine A4100” manufactured by Toyobo Co., Ltd.)
・ Base resin: Acrylic ester

The base resin was polymerized by the following method.
Into a four-necked flask equipped with a stirrer, thermometer, reflux condenser, dropping funnel, nitrogen gas inlet tube was charged 120 parts of ethyl acetate and heated to 65 ° C. under a nitrogen gas stream. A mixture comprising 43 parts of methyl cyclohexyl methacrylate, 5 parts of butyl acrylate, 1 part of methacrylic acid, 1 part of 2-hydroxyethyl methacrylate and 0.25 part of AIBN was added dropwise over 2 hours, and the mixture was further maintained at the same temperature for 4 hours to hold a nonvolatile content. A 44.6% by weight acrylic resin solution was obtained. The number average molecular weight of the obtained polymer was about 300,000.

  The near-infrared absorbing dye was dissolved in a solvent (methyl ethyl ketone, toluene, ethyl acetate, etc.), and a resin and an antioxidant were mixed to obtain a paint.

  In the present invention, other acrylates that can be used include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, t-butyl acrylate, 3-ethoxypropyl acrylate, isopropyl methacrylate, n-propyl methacrylate, (Meth) acrylic acid esters such as 4-methylcyclohexylmethyl methacrylate, cyclohexyl methacrylate, ethyl methacrylate, methyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylic acid, and methacrylic acid can be used. These acrylic polymers can be used by copolymerizing two or more kinds as required.

Next, using the coating material, a dye-containing resin layer was formed on the coated substrate by the following method.
The coating material was apply | coated so that the resin film thickness after drying might be set to 10 micrometers on an application | coating base material using the film applicator. Next, it was dried in an oven at 150 ° C. for 5 minutes.

  About the optical characteristic of the obtained sample, the spectral transmittance was measured with the spectral reflectance measuring device. The spectral transmittance curve obtained by the measurement is shown in FIG. 15A. Table 1 shows the average transmittance of light between wavelengths of 400 nm and 700 nm and the average transmittance of light between wavelengths of 850 nm and 1150 nm.

  An optical filter sample was placed between the polarization separation element and the prism sheet in the liquid crystal display structure (see FIG. 3), and the distance at which the remote controller could be operated was evaluated by the following method.

  First, the liquid crystal display (42-inch liquid crystal television manufactured by Sony Corporation) 10 and the optical disk device (DVD player made by Sony Corporation) 30 are placed in the positional relationship shown in FIG. 18, and the display screen of the liquid crystal display 10 and the remote control light receiving unit of the optical disk device 30 are placed. It was opposed to 30A by 1 meter. In this state, immediately after the liquid crystal display 10 is operated, the tester holding the remote controller 31 confirms the longest distance that the remote controller operation of the optical disc device 30 is possible while moving back and forth. It was determined that the longer the distance, the greater the remote control operation guarantee effect. The signal wavelength region of the remote control 31 is 930 nm to 960 nm, and the light receiving sensitivity region of the remote control light receiving unit 30A is 850 nm to 1150 nm.

  Further, the luminance at the center of the screen of the liquid crystal display 10 was measured using a spectral luminance meter (“CS1000A” manufactured by Konica Minolta Co., Ltd.), and the luminance reduction rate relative to the case where no optical filter sample was installed was obtained. Table 2 shows the measurement results of the remote control operable distance and the display brightness.

(Example 2)
The remote control operable distance and display brightness were evaluated by the same method as in Example 1 above, except that the thickness of the dye-containing resin layer was changed to a sample configuration that gives the spectral characteristics shown in FIG. 15B and Table 1. went. The measurement results are shown in Table 2. The thickness of the dye layer was adjusted by the solid content concentration of the paint (the same applies hereinafter).

(Example 3)
The remote control operable distance and display brightness were evaluated by the same method as in Example 1 above, except that the thickness of the dye-containing resin layer was changed to obtain a sample configuration capable of obtaining the spectral characteristics shown in FIG. 15C and Table 1. went. The measurement results are shown in Table 2.

Example 4
As in Example 1, a coating material was first prepared by the following method.
A mixture of the following materials was mixed using a stirrer to obtain a pigment paint.
・ Near-infrared absorbing dye: 1 part by weight of cyanine compound ・ Base resin: 10 parts by weight of polymethyl methacrylate resin ・ Solvent: 65 parts by weight of toluene

A sample of an optical film was produced as follows using the obtained paint.
As a transparent support, a coating was applied to the main surface of a PET film (thickness: 188 μm, “U426” manufactured by Toray Industries, Inc.) by microgravure. The film thickness of the coating film was adjusted by the number of gravure lines. This coating film was dried at 90 ° C. to form a dye layer.

  About the optical characteristic of the obtained sample, the spectral transmittance was measured with the spectral reflectance measuring device. A spectral transmittance curve obtained by the measurement is shown in FIG. 16A. Table 1 shows the average transmittance of light between wavelengths of 400 nm and 700 nm and the average transmittance of light between wavelengths of 850 nm and 1150 nm. Table 2 shows the measurement results when the remote control operable distance and the display brightness were evaluated by the same method as in Example 1.

(Example 5)
A fluorine resin (“Cytop” manufactured by Asahi Glass Co., Ltd.) as an antireflection film was applied to both surfaces of the sample produced in Example 1 by a dip coating method. By adjusting the pulling rate during coating, the film thickness of this fluororesin film was set to 95 nm.

  About the optical characteristic of the obtained sample, the spectral transmittance was measured with the spectral reflectance measuring device. The spectral transmittance curve obtained by the measurement is shown in FIG. 16B. Table 1 shows the average transmittance of light between wavelengths of 400 nm and 700 nm and the average transmittance of light between wavelengths of 850 nm and 1150 nm. Table 2 shows the measurement results when the remote control operable distance and the display brightness were evaluated by the same method as in Example 1.

(Example 6)
Using the paint prepared in Example 1, a pigment-containing resin layer was applied to the surface opposite to the prism surface of the prism sheet (prism sheet 15 in FIG. 3) so as to have the same film thickness as in Example 1. The obtained sample was incorporated into a liquid crystal display, and the remote control operable distance and display luminance were evaluated by the same method as in Example 1. The measurement results are shown in Table 2.

(Example 7)
The pigment-containing resin layer produced in Example 1 was bonded to the surface opposite to the prism surface of the prism sheet (prism sheet 15 in FIG. 3) using an adhesive film. The obtained sample was incorporated into a liquid crystal display, and the remote control operable distance and display luminance were evaluated by the same method as in Example 1. The measurement results are shown in Table 2.

(Example 8)
On the pigment-containing resin layer of the prism sheet sample prepared in Example 7, a fluorine-based resin layer was further applied using a gravure coater. The thickness was adjusted to 95 nm depending on the paint concentration. The obtained sample was incorporated into a liquid crystal display, and the remote control operable distance and display luminance were evaluated by the same method as in Example 1. The measurement results are shown in Table 2.

Example 9
The pigment | dye containing resin layer produced in Example 1 was bonded together using the adhesive film on the surface at the side of the backlight of a diffusion sheet (diffusion sheet 14 of FIG. 3). The obtained sample was incorporated into a liquid crystal display, and the remote control operable distance and display luminance were evaluated by the same method as in Example 1. The measurement results are shown in Table 2.

(Example 10)
The sample of the optical filter produced in Example 5 was installed on the outermost surface of the liquid crystal display panel of the liquid crystal display (the surface in contact with the outside air), and the remote control operable distance and display luminance were evaluated by the same method as in Example 1. It was. The measurement results are shown in Table 2.

(Example 11)
The coating material produced in Example 1 was applied on the TAC film used for the polarizing plate installed on the back side (light incident surface side) of the liquid crystal display panel to constitute the optical filter according to the present invention. Table 1 shows the average transmittance of light between wavelengths of 400 nm and 700 nm and the average transmittance of light between wavelengths of 850 nm and 1150 nm for the optical characteristics of the obtained sample. Further, the remote control operable distance and the display brightness were evaluated by the same method as in Example 1. Furthermore, the chromaticity change of the display image after installation with respect to the optical filter before installation was measured using a color luminance meter (“CS1000” manufactured by Konica Minolta). Table 3 shows the measurement results.

(Example 12)
The dye-containing resin layer used in Example 2 was applied on the TAC film used for the polarizing plate installed on the back side of the liquid crystal display panel in the same manner as in Example 11 to constitute the optical filter according to the present invention. did. The spectral characteristics of the obtained sample are shown in Table 1, and the measurement results of remote control operable distance, display luminance, and chromaticity change are shown in Table 3.

(Example 13)
The dye-containing resin layer used in Example 3 was applied on the TAC film used for the polarizing plate installed on the back side of the liquid crystal display panel in the same manner as in Example 11 to constitute the optical filter according to the present invention. did. The spectral characteristics of the obtained sample are shown in Table 1, and the measurement results of remote control operable distance, display luminance, and chromaticity change are shown in Table 3.

(Example 14)
A mixture of the following materials was mixed using a stirrer to prepare a pigment paint.
Near-infrared absorbing dye: diimmonium salt (“CIR-1085” manufactured by Nippon Carlit Co., Ltd.)
Base resin: Acrylic resin (“IR-G205” manufactured by Nippon Shokubai)
・ Solvent: Mixed solvent of MEK (methyl ethyl ketone) and TOL (toluene)

  The obtained paint was applied on the TAC film used for the polarizing plate installed on the back side of the liquid crystal display panel in the same manner as in Example 11 to constitute the optical filter according to the present invention. The spectral characteristics of the obtained sample are shown in FIG. 17A and Table 1, and the measurement results of the remote control operable distance, display luminance, and chromaticity change are shown in Table 3.

(Example 15)
The remote control operable distance, display brightness, and chromaticity change were performed in the same manner as in Example 14 except that the thickness of the dye-containing resin layer was changed to obtain a sample configuration capable of obtaining the spectral characteristics shown in FIG. 17B and Table 1. Was evaluated. Table 3 shows the measurement results.

(Example 16)
The remote control operable distance, display brightness, and chromaticity change are the same as in Example 14 described above except that the thickness of the dye-containing resin layer is changed to obtain a sample configuration capable of obtaining the spectral characteristics shown in FIG. 17C and Table 1. Was evaluated. Table 3 shows the measurement results.

(Example 17)
A paint was prepared in the same manner as in Example 1 using the following dyes.
Near-infrared absorbing dye: diimmonium salt (“CIR-1085” manufactured by Nippon Carlit Co., Ltd.)
Base resin: Acrylic resin (IR-G205 made by Nippon Shokubai)
・ Solvent: Mixed solvent of MEK and TOL ・ Coating substrate: TAC (triacetylcellulose) film (Fuji Photo Film Co., Ltd.)

  A pigment-containing resin layer was produced on the TAC film by using a cap coater utilizing capillary action on the TAC film. When the spectral characteristics of the obtained optical filter were measured by the same method as in Example 1, the same characteristics as the spectral characteristics shown in FIG. 15A were obtained. Table 1 shows the average transmittance of light between wavelengths of 400 nm and 700 nm and the average transmittance of light between wavelengths of 850 nm and 1150 nm.

  Further, the obtained optical filter sample is placed between the polarization separation element in the liquid crystal display structure and the liquid crystal display panel, and the remote control operable distance and the display brightness are evaluated by the same method as in the first embodiment. It was. The measurement results are shown in Table 2.

(Example 18)
The remote control operable distance and display brightness were evaluated by the same method as in Example 1 above, except that the thickness of the dye-containing resin layer was changed to a sample configuration that gives the spectral characteristics shown in FIG. 15B and Table 1. went. The measurement results are shown in Table 2.

(Example 19)
The remote control operable distance and display brightness were evaluated by the same method as in Example 1 above, except that the thickness of the dye-containing resin layer was changed to obtain a sample configuration capable of obtaining the spectral characteristics shown in FIG. 15C and Table 1. went. The measurement results are shown in Table 2.

(Example 20)
The coating material substrate prepared in Example 17 was used as a liquid crystal display panel, and the coating material was coated on the back surface (backlight side surface) of the liquid crystal display panel. A liquid crystal display was constructed using the obtained liquid crystal display panel, and the remote control operable distance and display luminance were evaluated by the same method as in Example 1. The measurement results are shown in Table 2.

  In addition, since the pigment-containing resin layer was directly applied to the liquid crystal display panel, the spectral characteristics of the pigment-containing resin layer could not be grasped. However, by combining the coating material of Example 17 with the solid content concentration and coating conditions, Example 17 It was assumed that almost equivalent characteristics were obtained.

(Example 21)
The coating base material of the paint prepared in Example 17 was an easily peelable film, and a dye-containing resin layer was applied only on one side thereof, which was used as a coating film. When the spectral characteristics of the obtained coated film were measured by the same method as in Example 1, the same characteristics as the spectral characteristics shown in FIG. 15A were obtained. Table 1 shows the average transmittance of light between wavelengths of 400 nm and 700 nm and the average transmittance of light between wavelengths of 850 nm and 1150 nm.

  Next, the surface of the coating film on the dye-containing resin layer side and another easily peelable film are bonded together via an adhesive layer, and then the easily peelable film is peeled off to form the adhesive layer surface and the liquid crystal display panel. The back surface (backlight side surface) was bonded together. The series of steps corresponds to the steps shown in FIG. A liquid crystal display was constructed using the obtained liquid crystal display panel, and the remote control operable distance and display luminance were evaluated by the same method as in Example 1. The measurement results are shown in Table 2.

(Comparative Example 1)
With the liquid crystal display turned off, the remote control operable distance was measured by the same method as in Example 1. The measurement results are shown in Table 2.

(Comparative Example 2)
The remote control operable distance was measured by the same method as in Example 1 without installing the optical filter according to the present invention in the liquid crystal display. The measurement results are shown in Table 2.

(Comparative Example 3)
Except for changing the thickness of the dye-containing resin layer to obtain a sample configuration capable of obtaining the spectral characteristics shown in FIG. 19A and Table 1, the remote control operable distance and display luminance were evaluated in the same manner as in Example 1 above. went. The measurement results are shown in Table 2.

(Comparative Example 4)
Except for changing the thickness of the dye-containing resin layer to obtain a sample configuration capable of obtaining the spectral characteristics shown in FIG. 19B and Table 1, the remote control operable distance and display luminance were evaluated in the same manner as in Example 1 above. went. The measurement results are shown in Table 2.

(Comparative Example 5)
The remote control operable distance and display brightness were evaluated by the same method as in Example 1 above, except that the type of the near infrared absorbing dye was changed to a sample configuration capable of obtaining the spectral characteristics shown in FIG. 19C and Table 1. went. The measurement results are shown in Table 2.

(Comparative Example 6)
The remote control operable distance and display luminance were evaluated by the same method as in Example 1 except that the sample configuration was obtained by changing the type of near-infrared absorbing dye and obtaining the spectral characteristics shown in FIG. 19A and Table 1. went. The measurement results are shown in Table 2.

(Comparative Example 7)
The remote control operable distance and display luminance were evaluated by the same method as in Example 1 except that the sample configuration was obtained by changing the type of the near infrared absorbing dye to obtain the spectral characteristics shown in FIG. 19B and Table 1. went. The measurement results are shown in Table 2.

  From the comparative example 1 and the comparative example 2, the remote control operable distance is significantly reduced in the comparative example 2 in which the power is turned on, compared to the comparative example 1 in which the liquid crystal display is not turned on. Recognize. From this result, it can be seen that the infrared rays emitted from the liquid crystal display can affect the remote control operation of the peripheral device.

  With respect to this remote control operation failure, in Examples 1 to 10 and Examples 17 to 21, the remote control operation distance can be improved by providing an optical filter having an infrared cut function according to the present invention in the liquid crystal display. Recognize.

  That is, as shown in FIGS. 15, 16 and Table 1, the average transmittance of light having a wavelength of 400 nm to 700 nm is 85% or more, and the average transmittance of light having a wavelength of 850 nm to 1150 nm is 85%. In more detail below, it can be seen that it is 60% or less. Further, as shown in Table 2, when the remote control operable distances of Examples 1 to 10, 17 to 21 and Comparative Example 2 are compared, the remote control operable distance is obtained by installing the optical filter sample according to the present invention. It can be seen that is at least twice as long.

  Regarding display brightness, according to Examples 1 to 10 and Examples 17 to 21, the display brightness can be suppressed to 10% or less. Further, Example 5 is a case where an antireflection film is formed on the surface of the sample manufactured in Example 1, and it can be seen that the luminance reduction rate can be suppressed lower than that in Example 1.

  Furthermore, regarding Examples 6 to 10, when the optical filter according to the present invention is integrated with an optical film such as a prism sheet installed in a liquid crystal display, the installation position of the optical filter is different from Example 1. In this case, the remote control operable distance similar to that of the first embodiment is ensured although there is some difference in the luminance reduction rate.

  In addition, regarding Comparative Example 3 and Comparative Example 6, the reason why the luminance reduction rate exceeds 10% is considered to be that the average transmittance value in the visible wavelength range of 400 nm to 700 nm is less than 85%. It is done. Further, in Comparative Examples 4 and 5, the remote control operable distance is almost the same as in Comparative Example 2 because the average transmittance of light having a wavelength of 850 nm to 1150 nm in the near infrared region exceeds 85%. Because.

  On the other hand, for Examples 11 to 16, the same effect as in Examples 1 to 10 can be obtained by using the optical filter according to the present invention in combination with the polarizing plate set on the back side of the liquid crystal display panel. I understand. In particular, even if a dye-containing resin layer having the same configuration is used as in Example 2 and Example 12, Example 3 and Example 13, remote control operation is possible by changing the installation location of this dye-containing resin layer. It can be seen that different results are obtained for the distance and the luminance reduction rate. That is, since the effect of the dye-containing resin layer varies depending on the installation site of the dye-containing resin layer, it can be seen that optimization of the configuration of the dye-containing resin layer according to the installation site is necessary.

  From the above results, by installing the optical filter (optical element) according to the present invention inside the liquid crystal display or on the panel surface side, it is an effective means for reducing the near-infrared radiation amount without greatly affecting the image quality. It was confirmed that there was.

(Example 22)
In this example, a sample of an optical filter as an optical element according to the present invention composed of a dye-containing adhesive resin layer in which a near-infrared absorbing dye was dispersed in an adhesive was prepared by the following procedure.

[Coating composition]
First, a coating material for the dye-containing pressure-sensitive adhesive resin layer was prepared. The materials used are shown below.
Near-infrared absorbing dye: diimmonium salt (“CIR-1085” manufactured by Nippon Carlit Co., Ltd.)
Antioxidant: Phosphite-based antioxidant (Adeka Stub 1178 manufactured by Asahi Denka Kogyo Co., Ltd.)
・ Coating substrate: Silicone-treated polyester film substrate (“01” manufactured by Tosero)
・ Base resin: Polyacrylic ester resin ・ Crosslinking agent: “Coronate L” manufactured by Nippon Polyurethane Co., Ltd. 1 part

The base resin was polymerized by the following method.
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, dropping funnel, nitrogen gas inlet tube was charged with 120 parts of ethyl acetate and heated to 65 ° C. under a nitrogen gas stream. A mixture of 10 parts, 78 parts of butyl acrylate, 1 part of methacrylic acid, 1 part of 2-hydroxyethyl methacrylate and 0.25 part of AIBN was added dropwise over 2 hours, and the mixture was further maintained at the same temperature for 4 hours to hold a nonvolatile content of 44.0 A weight percent acrylic resin solution was obtained. The weight average molecular weight of the obtained polymer was about 950,000.

And the resin for adhesives, a near-infrared absorption pigment | dye, antioxidant, and a crosslinking agent were mixed, and it apply | coated to the base material so that the resin film thickness after drying might become predetermined thickness using a film applicator. Next, it was dried in a 110 ° C. oven for 5 minutes. At this time, samples 1 to 11 were prepared as shown in Table 3 by changing the concentration per unit area (g / m ² ), blending amount (/ 100 g of resin), and coating thickness of the near-infrared absorbing pigment to be blended. Each prepared sample is bonded to an AR film with a laminator, and then the AR film provided with the sample is bonded to a polarizing plate to form a liquid crystal display panel, and the light transmittance at wavelengths of 550 nm, 900 nm, and 1015 nm is measured. did. Table 4 shows the measurement results.

  From the results of Table 4, the larger the dye concentration, dye blending amount, or film thickness of the dye-containing adhesive resin layer can reduce the near-infrared transmittance at wavelengths of 900 nm and 1015 nm, but the visible light at a wavelength of 550 nm. It can be seen that the transmittance also tends to decrease. Therefore, an optical filter having desired spectral characteristics can be configured by appropriately adjusting the dye concentration, the dye blending amount, and the film thickness.

  As mentioned above, although embodiment and the Example of this invention were described, of course, this invention is not limited to these, A various deformation | transformation is possible based on the technical idea of this invention.

  For example, in each of the above-described embodiments, the example in which the optical filter according to the present invention is installed on the polarization separation element, the prism sheet, the diffusion sheet, the diffusion plate, or the outer surface side or the rear surface side of the liquid crystal display panel in the liquid crystal display has been described. Instead of or in addition to this, the optical filter according to the present invention may be installed in the backlight unit.

  FIG. 20 shows an example in which the optical filter 9a according to the present invention is provided on the surface (light reflecting surface) of the reflecting plate 9 of the backlight unit 12. The optical filter 9a is composed of a dye-containing resin layer in which a near-infrared absorbing dye is dispersed in a binder resin, as in the above-described embodiments, and is applied or pasted on the surface of the reflecting plate 9. Even with such a configuration, the backlight light emitted from the light source 8 and reflected by the reflecting plate 12 is emitted from the liquid crystal display panel 11 by reducing the transmittance of light in the wavelength region in which the remote control light receiving unit is sensitive. It is possible to effectively suppress a decrease in remote control sensitivity due to infrared rays. Moreover, you may provide an ultraviolet absorption layer in the surface of the reflecting plate 9 instead of the optical filter 9a or in addition to the optical filter 9a.

It is a figure explaining the relationship between remote control signal wavelength and remote control light-receiving part sensitivity. It is a figure which shows the emission spectrum of the infrared rays radiated | emitted from a liquid crystal display. It is a schematic sectional drawing which shows the structure of the liquid crystal display by the 1st Embodiment of this invention. It is a schematic sectional drawing which shows the structural example of the optical filter as an optical element by the 1st Embodiment of this invention. It is a figure explaining the difference in the reflectance characteristic of the optical filter of FIG. 4A, and the optical filter of FIG. 4B. It is a figure which shows an example of the spectral transmittance characteristic of the optical filter shown in FIG. It is a schematic sectional drawing which shows the structure of the liquid crystal display by the 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the structural example of the optical filter as an optical element by the 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the other structural example of the optical filter shown in FIG. It is a schematic sectional drawing which shows the structure of the liquid crystal display by the 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the structural example of the optical filter as an optical element by the 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the liquid crystal display by the 4th Embodiment of this invention. It is process sectional drawing which shows typically the example of attachment of the optical filter as an optical element by the 4th Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the liquid crystal display by the 5th Embodiment of this invention. It is a spectral transmittance curve of the optical filter which concerns on Examples 1-3 of this invention. It is a spectral transmittance curve of the optical filter which concerns on Example 4, 5 of this invention. It is a spectral transmittance curve of the optical filter which concerns on Examples 14-16 of this invention. It is a figure explaining the characteristic evaluation method of the optical filter demonstrated in the Example of this invention. It is a spectral transmittance curve of the optical filter which concerns on Comparative Examples 3-5 of this invention. It is a schematic sectional drawing which shows the modification of the structure of the liquid crystal display which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal layer, 2a, 2b ... Transparent substrate, 3a, 3b ... Polarizing plate, 4A, 4B, 4C, 4D, 4E, 9a ... Optical filter (optical element), 5, 5E ... Transparent base material, 6 ... Dye containing Resin layer, 7a, 7b ... antireflection film, 8 ... linear light source, 9 ... reflector, 10A, 10B, 10C ... liquid crystal display, 11 ... liquid crystal display panel, 12 ... backlight unit, 13 ... diffuser plate, 14 ... Diffusion sheet, 15 ... prism sheet, 16 ... polarization separation element, 20 ... adhesive layer, 21 ... AR film, 22 ... hard coat layer, 24 ... dye-containing adhesive resin layer

Claims (24)

A liquid crystal display panel;
A backlight unit comprising a cold cathode tube;
A liquid crystal display comprising: an optical element that transmits light in a visible region and absorbs part of a wavelength in an infrared region. The liquid crystal display according to claim 1, wherein the optical element is disposed between the liquid crystal display panel and the backlight unit. The liquid crystal display according to claim 2, wherein the optical element is provided integrally with an optical film disposed between the liquid crystal display panel and the backlight unit. A reflective polarization separation element is disposed between the liquid crystal display panel and the backlight unit, and the optical element is located between the liquid crystal display panel and the reflective polarization separation element. The liquid crystal display according to claim 2. The liquid crystal display according to claim 2, wherein an ultraviolet absorbing layer is provided between the backlight unit and the optical element. The liquid crystal display according to claim 1, wherein the optical element is provided integrally with the liquid crystal display panel. The liquid crystal display according to claim 6, wherein the optical element is provided on a front side of the liquid crystal display panel. An antireflection layer or a hard coat layer is provided on the front side of the liquid crystal display panel, and the optical element is provided integrally with the antireflection layer or the hard coat layer. Item 8. A liquid crystal display according to item 7. On the front side of the liquid crystal display panel, an antireflection layer or a hard coat layer is provided via an adhesive layer, and the optical element comprises the adhesive layer containing a near infrared absorbing dye. The liquid crystal display according to claim 7. The liquid crystal display according to claim 7, wherein an ultraviolet absorbing layer is provided on an outer surface side of the optical element. The liquid crystal display according to claim 6, wherein the optical element is provided on a back side of the liquid crystal display panel. The backlight unit includes a light source and a reflector that reflects light emitted from the light source,
The liquid crystal display according to claim 1, wherein the optical element is provided on a light reflecting surface of the reflecting plate. The liquid crystal display according to claim 1, wherein the optical element is made of a resin composition containing a near-infrared absorbing dye. The liquid crystal display according to claim 13, wherein the optical element is formed by applying the resin composition to a base material. The liquid crystal display according to claim 14, wherein an optical film for reducing the reflectance is applied to the coated surface or the back surface side of the base material. The optical element is formed by directly applying the resin composition to a liquid crystal display panel or an optical film disposed between the liquid crystal display panel and a backlight unit. LCD display. The optical element is formed by bonding the resin composition to a liquid crystal display panel or an optical film disposed between the liquid crystal display panel and a backlight unit via an adhesive layer. Item 14. A liquid crystal display according to item 13. The liquid crystal display according to claim 13, wherein the resin composition includes one or more near-infrared absorbing dyes and a binder resin. The near-infrared absorbing dye is composed of an ammonium salt, an aminium salt, an iminium salt, a diiminium salt, a diimmonium salt, a quinone, a phthalocyanine, a naphthalocyanine, a cyanine, a metal complex, or a mixture thereof. LCD display. The liquid crystal display according to claim 18, wherein the binder resin is a polyester resin, an acrylic resin, a polyamide resin, a polyurethane resin, a polyolefin resin, or a polycarbonate resin. 2. The liquid crystal display according to claim 1, wherein the optical element has an average transmittance of 85% or more for light having a wavelength of not less than 400 nm and not more than 700 nm. The liquid crystal display according to claim 21, wherein the optical element has a light transmittance average value of 85% or less at a wavelength of 850 nm to 1150 nm. 2. The liquid crystal according to claim 1, wherein a reduction rate of the display brightness of the liquid crystal display when the optical element is provided is 10% or less with respect to the display brightness of the liquid crystal display when the optical element is not provided. display. Used in combination with a liquid crystal display panel equipped with a cold cathode tube as a backlight,
An optical element that transmits light in the visible region and absorbs part of the wavelength in the infrared region.

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