JP2006189677A - Highly transmissive polarizing plate and liquid crystal projector using same, liquid crystal rear projection television - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly transmissive polarizing plate with which the reduction of contrast can be prevented even when displacement of an optical axis is generated in a polarizing plate with high transmissivity which is to be arranged between a polarizing plate of the incidence side of a liquid crystal projector and a polarizing plate of the emission side of the porjector. <P>SOLUTION: In manufacturing the highly transmissive polarizing plate, the highly transmissive polarizing plate which has a phase difference value which is optimized to the wavelength of light which is used in a liquid crystal projector is manufactured while controlling the phase difference value by controlling the thickness and the stretching magnification, etc., of a polyvinyl alcohol(PVA)-based film. The highly transmissive polarizing plate said here is used by being arranged between the polarizing plate of the incidence side of the liquid crystal projector and the polarizing plate of the emission side of the projector, and is used in order to raise the lives of the polarizing plates by being incorporated between a liquid crystal panel and the polarizing plate of the emission side of the projector. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-transmission polarizing plate useful for home theater liquid crystal projectors, data projection liquid crystal projectors, liquid crystal rear projection televisions, and the like.

  Highly transmissive polarizing plate used to enhance the life-span effect of polarizing plates used in liquid crystal projectors and liquid crystal rear projection televisions (also called pre-polarizing plates and pre-polarizing plates. As a dispersion), a polymer film substrate such as a film of stretched and oriented polyvinyl alcohol (PVA) or a derivative thereof is made to contain iodine or a dichroic dye as a polarizing element, and both surfaces or one surface thereof is supported by a support film. You are using a protected one. However, in general, when producing a polarizing plate, the PVA film is stretched as much as possible without managing the retardation value, and high optical properties are realized by arranging dye molecules dyed on it as high as possible. Yes. Paragraph No. 0034 of Patent Document 1 and Paragraph No. 0038 of Patent Document 2 describe that a polarizing plate having a high transmittance (pre-polarizing plate) is used as the polarizing means on the output side and light absorption of the main polarizing plate is moderated. ing. Further, in paragraph No. 0015 of Patent Document 3, a plurality of polarizing plates (pre-polarizing plates) are provided on at least one of the exit side polarization unit and the exit polarization unit, so that the absorption of light is reduced and the durability of each polarization plate is improved. Although attempts have been made, none of the patent documents describes the control of the retardation value of the polarizing plate itself.

Japanese Patent Application Laid-Open No. 2004-220,000 Japanese Patent Laid-Open No. 2004-220001 Japanese Patent Laid-Open No. 10-133196 JP 59-145255 A JP-A-60-156759 Japanese Patent Laid-Open No. 3-12606 JP-A-11-218610 JP 2001-33627 A JP 2002-296417 A

  In recent years, a liquid crystal projector, a liquid crystal rear projection television, and the like have a strong demand for high contrast while demanding high brightness and long life durability. In order to achieve further improvement in brightness, the intensity of the light source used is increasing. The liquid crystal projector is a red light LCD and a green light LCD for the primary colors of light, that is, the red channel (R-ch), green channel (G-ch), and blue channel (B-ch). The blue color LCD is irradiated to obtain images of the respective primary colors, which are synthesized and projected by a dichroic prism or the like. At this time, a high transmission polarizing plate is incorporated and used in front of the output polarizing plate of each channel in order to increase the life extension effect of the output polarizing plate. However, there is a problem in that some liquid crystal projectors equipped with a highly transmissive polarizing plate manufactured by a manufacturing method that does not control the phase difference value of the related art have a significantly reduced contrast.

  As one of the factors that significantly reduce the contrast, the optical axis shift at the time of raw roll of the high transmission polarizing plate and the chip cut to the substrate size, and further artificially generated when the cut chip is bonded to the substrate The occurrence of optical axis misalignment can be mentioned. When the deviation of the optical axis with respect to the incident polarizing plate was ± 0.5 to 2.0 °, a phenomenon was observed in which the contrast was reduced by about 30% in the projector mounted with the polarizing plate.

  In order to solve the above-mentioned problems, various studies were conducted to develop a highly transmissive polarizing plate that does not decrease the contrast even when the optical axis shift occurs during the original fabric, during cutting, and during pasting. It was found that there was a cause in its own phase difference value.

  As the retardation value of the high-transmission polarizing plate, the high-transmission polarizing plate used for the R-ch is a retardation value close to the wavelength of the light beam used as the R-ch. For the G-ch, it is used for the G-ch. Optical axis misalignment of original high-transmission polarizing plate at the time of drawing and cutting by setting the phase difference value close to the wavelength of the light beam, and for B-ch, the phase difference value close to the wavelength of the light beam used for B-ch The inventors have found that a highly transmissive polarizing plate can be produced in which the contrast does not decrease even when there is a slight shift of the optical axis that occurs during pasting.

That is, the present invention
(1) In a high transmission polarizing plate provided between an incident side and an outgoing side polarizing plate of a liquid crystal projector, the relationship between the retardation value R (nm) and the wavelength λ (nm) of light used is R = nλ ± 100 (Where n is an integer 1 or 2), a liquid crystal projector using a high transmission polarizing plate,
(2) A high transmission polarizing plate for a red channel (R-ch) having a retardation value of 480 to 800 nm or 1,060 to 1,500 nm.
(3) A high transmission polarizing plate for a green channel (G-ch) having a retardation value of 400 to 700 nm or 900 to 1,300 nm,
(4) A high transmission polarizing plate for a blue channel (B-ch) having a retardation value of 300 to 600 nm or 700 to 1,100 nm.
(5) A liquid crystal projector using the high transmission polarizing plate according to any one of (2) to (4),
(6) High transmission polarizing plate for red channel (R-ch), green channel (G-ch) and blue channel (B-ch) The plate is the high transmission polarizing plate described in (2), the green channel (R-ch) high transmission polarizing plate is the high transmission polarizing plate described in (3) and the blue channel (R-ch) high transmission polarizing plate The liquid crystal projector according to (5), wherein the plate is the high transmission polarizing plate according to (4),
(7) A liquid crystal rear projection television using the liquid crystal projector according to any one of (1), (5) or (6),
(8) A high transmission polarizing plate for a red channel (R-ch) having a retardation value of 550 to 750 nm or 1,160 to 1,360 nm.
(9) A high transmission polarizing plate for a green channel (G-ch) having a retardation value of 450 to 650 nm or 1,000 to 1,200 nm,
(10) A high transmission polarizing plate for a blue channel (B-ch) having a retardation value of 350 to 550 nm or 800 to 1,000 nm.
About.

  By using a high-transmission polarizing plate having a specific retardation value, the optical axis shift distribution of the original polarizing film and the reduction in contrast due to optical axis shift that occurs artificially at the time of cutting and bonding are prevented. I can do it. Stable liquid crystal projectors and liquid crystal rear projection televisions in which the contrast is not reduced by using this highly transmissive polarizing plate with controlled retardation value for each wavelength of light of each channel (R-ch, G-ch, B-ch) It has become possible to manufacture automatically.

The present invention is described in detail below.
The polarizing element of the polarizing element film of the high transmission polarizing plate used in the present invention may be iodine type or dye type, but a dye type having higher durability is preferable. The high-transmitting polarizing plate dyes a polymer film with iodine or a dichroic dye, and then produces a polarizing element film having a thickness of 10 to 70 μm by uniaxially stretching the polymer film 3 to 10 times. If necessary, this polarizing element film can be produced by sandwiching it with a support film which is a protective layer provided on both sides and one side. Alternatively, dyeing and uniaxial stretching may be performed simultaneously by uniaxially stretching the polymer film and then dyeing with iodine or a dichroic dye. Examples of the uniaxial stretching method of the polymer film include a wet method and a dry method.

  As the polymer film, for example, a polyvinyl alcohol (PVA) film or vinyl alcohol and an olefin such as ethylene or propylene, an unsaturated carboxylic acid such as crotonic acid, acrylic acid, methacrylic acid, maleic acid, or the like is copolymerized. Examples include modified films, polymer films such as ethylene / vinyl acetate (EVA) resin, saponified EVA resin, nylon resin, and polyester resin. PVA-based films are preferable from the viewpoint of dye adsorption and orientation. Examples of the PVA film include a PVA film and a polyvinyl butyral film, and a PVA film is preferable. As for the polymerization degree of PVA used in preparation of a highly transmissive polarizing plate, 2,000-5,000 are preferable.

  Moreover, as a pigment | dye used as a deflection | deviation element of the high transmittance polarizing plate of this invention, Preferably a dichroic organic dye is used. The organic dye may be used in combination with one or more organic dyes as necessary, and is preferably a dye having absorption characteristics in a predetermined wavelength region and having high dichroism. Specific examples thereof include, for example, C.I. Eye. direct. Yellow 12, sea. Eye. direct. Yellow 28, Sea. Eye. direct. Yellow 44, Sea. Eye. direct. Orange 26, Sea. Eye. direct. Orange 39, sea. Eye. direct. Orange 107, sea. Eye. direct. Red 2, sea. Eye. direct. Red 31, sea. Eye. direct. Red 79, Sea. Eye. direct. Red 81, Sea. Eye. direct. Red 247, Sea. Eye. direct. Green 80, Sea. Eye. direct. Green 59, Sea. Eye. direct. Blue 237 and dyes described in Patent Literature 4, Patent Literature 5, Patent Literature 6, Patent Literature 7, Patent Literature 8, and Patent Literature 9 are listed. These dyes are free acids or alkali metal salts. , Ammonium salts, and salts of amines.

  When other organic dyes are used in combination as required, the type of dye to be blended differs depending on whether the target polarizing film is a neutral color polarizing film, a color polarizing film for liquid crystal projectors, or other color polarizing films. . The blending ratio is not particularly limited.

  In order to contain an organic dye or a salt thereof in the polymer film, a method of dyeing the polymer film is usually employed. For example, the staining is performed as follows. First, an organic dye is dissolved in water to prepare a dye bath. The dye concentration in the dye bath is selected in the range of about 0.1 to 10% by weight for a normal input / output polarizing plate, whereas the range of about 0.001 to 1% by weight for a high transmission polarizing plate is usually used. Selected from. Further, a dyeing assistant may be used if necessary. For example, it is preferable to use sodium sulfate at a concentration of about 0.1 to 10% by weight. The polymer film is immersed in the dye bath thus prepared for 0.5 to 10 minutes and dyed. The dyeing temperature is preferably about 20 to 80 ° C.

  Orientation of the organic dye is performed by stretching a dyed polymer film. As a stretching method, any known method such as a wet method or a dry method may be used. The stretching of the polymer film may optionally be performed before dyeing. In this case, the organic dye is oriented at the time of dyeing. The polymer film containing and orienting the organic dye is subjected to post-treatment such as boric acid treatment by a known method as necessary. Such post-processing is performed for the purpose of improving the light transmittance and the degree of polarization of the polarizing element film. The conditions for the boric acid treatment vary depending on the type of polymer film used and the type of dye used, but generally the boric acid concentration of the boric acid aqueous solution is 0.1 to 15% by weight, preferably 1 to 10% by weight. The treatment is performed by dipping at a temperature of 30 to 80 ° C., preferably 40 to 75 ° C., for 0.5 to 10 minutes. Further, if necessary, the fixing treatment may be performed with an aqueous solution containing a cationic polymer compound after dyeing.

  In the iodine dyeing treatment, after swelling the polymer film, the polymer film described above is immersed in an iodine solution such as an aqueous solution containing iodine and potassium iodide, and further in a dyeing solution containing boric acid. It is done by. When using an aqueous solution, it is preferable to use iodine and potassium iodide in the aqueous solution at a concentration of usually 0.01 to 0.3% by weight of iodine and 0.01 to 3% by weight of potassium iodide. is there. The dyeing temperature is preferably 20 to 50 ° C., and the dyeing time is preferably about 10 to 300 seconds. The stretching method of the iodine dyed polymer film is preferably the same treatment as in the case of the organic dye described above.

  A polarizing element film alone has a sufficient polarizing function, but is usually sandwiched between support films in order to impart sufficiently high durability against severe light irradiation, high temperature or high temperature and high humidity. The support film is preferably a support film such as triacetyl cellulose (TAC) containing an ultraviolet absorber, and is preferably laminated and bonded from both sides to form a highly transmissive polarizing plate. Specific examples of the support film include, for example, cellulose acetate film such as TAC, acrylic film, fluorine film such as tetrafluoroethylene / hexafluoropropylene copolymer, polycarbonate resin, polyester resin, polyolefin resin or Although the film which consists of a polyamide-type resin is mentioned, a TAC film is preferable. The film thickness of the support film is 30 to 250 μm, preferably 50 to 190 μm.

  In the present invention, a transparent coating layer may be provided on the surface of the support film of the high transmission polarizing plate. Examples of the coating layer include acrylic and polysiloxane hard coat films and urethane films. Further, an antireflection (AR) layer may be provided on the protective film. As the AR layer, for example, a material such as silicon dioxide or titanium oxide can be formed by vapor deposition or sputtering treatment, or it can be formed by thinly applying a fluorine-based material.

  In the present invention, the retardation value of the polarizing element film of the high transmission polarizing plate can be controlled by changing various conditions such as the composition of the polymer film, the molecular weight or the thickness of the film, and the draw ratio. In producing a high transmission polarizing plate, a polarizing element film is laminated on both sides or one side by TAC and bonded, but the retardation film has a low retardation value so as not to affect the retardation value of the polarizing element film itself. Is preferably used.

Usually, the retardation value is increased by increasing the draw ratio. However, by increasing the draw ratio, the thickness of the polarizing element film itself is reduced and the retardation value is lowered. It was found that the thickness of the polarizing element film itself greatly contributed to the retardation value rather than the draw ratio. The retardation value (R) was measured with an automatic birefringence meter (manufactured by Oji Scientific).
R = Δn × d
Δn: film birefringence d: film thickness

  The phase difference value for each wavelength of light applied to the high transmission polarizing plate is described. For R-ch, a phase difference value of about 480 to 800 nm or about 1,060 to 1,500 nm is useful, The accuracy is further increased by setting it to 550 to 750 nm or 1,160 to 1,360 nm. Similarly, a phase difference value of 400 to 700 nm or 900 to 1,300 nm for G-ch is useful, preferably 450 to 650 nm or 1,000 to 1,200 nm, and a phase difference value of 300 to 1,200 nm for B-ch. Although 600 nm or about 700 to 1,100 nm is useful, it is preferable to set it to 350 to 550 nm or 800 nm to 1,000 nm, respectively.

The means for optimizing the retardation value (R) of the high transmission polarizing plate is as follows. In general, the behavior of the transmittance (Tc) when two polarizing plates are arranged orthogonally and an optical member having birefringence is arranged between them is expressed by the following formula (1). In Formula (1), when the phase difference value of the optical member having birefringence is equal to the wavelength of the light to be irradiated or the phase difference value is an integral multiple, (πR / λ) becomes π, 2π, and Sin ² (πR / Λ) is zero, that is, Tc is minimized. Thereby, an ideal phase difference value in the wavelength band of the irradiated light can be calculated. Actually, for B-ch, investigation was performed using phase difference values of 450 nm and 900 nm when πR / λ was π, 2π, but it was confirmed that Tc at a wavelength of 450 nm was minimized. Therefore, the phase difference value for B-ch (wavelength range: 400 to 500 nm) when the phase difference value is an integral multiple of the wavelength of the irradiated light is 300 to 600 nm or 700 to 1,100 nm, preferably 350. ˜550 nm or 800 to 1,000 nm. For R-ch (wavelength range: 580 to 680 nm), the phase difference value is 480 to 800 nm or 1,060 to 1,500 nm, preferably 550 to 750 nm or 1,160 to 1,360 nm, G-ch (wavelength (Area: 500 to 600 nm), the contrast is similarly reduced by preparing a polarizing element film having a retardation value of 400 to 700 nm or 900 to 1,300 nm, preferably 450 to 650 nm or 1,000 to 1,200 nm. Can be prevented.

Tc = Sin ² 2θ · Sin ² (πR / λ) (1)
θ: angle between the polarization direction and the optical axis of the birefringent optical member, R: retardation value of the optical member (nm), λ: wavelength of the irradiated light (nm)

  The spectrophotometer is used to measure the transmittance of the high-transmission polarizing plate. A high-contrast base polarizing plate for creating linearly polarized light is set in the same direction on the sample side and the reference side, and then calibrated. A spectrophotometer for setting the parallel transmittance or the orthogonal transmittance (hereinafter abbreviated as Tpol-c) and the orthogonal transmittance (hereinafter abbreviated as Tpol-c) at the incidence of polarized light by setting the high transmittance polarizing plate in the parallel or orthogonal position. It measured with U-4100 (made by Hitachi, Ltd.). The Tpol-p of the highly transmissive polarizing plate of the present invention is 85 to 93%, and Tpol-c is 5 to 80%, preferably 30 to 70%.

  Many liquid crystal projectors use optical systems such as a light source, a polarizing beam splitter, a polarizing plate, a liquid crystal cell, a cross prism, and a projection lens. The high transmission polarizing plate of the present invention is preferably provided between the incident side and the emission side of the liquid crystal projector, and more preferably provided in front of the emission side. High transmission polarizing plates for the red channel (R-ch), green channel (G-ch) and blue channel (B-ch) are provided at desired positions of the respective channels.

  By disposing the high transmission polarizing plate of the present invention having Tpol-c of 30 to 70% in front of the outgoing side polarizing plate, the outgoing side polarizing plate does not receive the total amount of light, but the amount of light received by the outgoing side polarizing plate. Controls and serves to reduce the temperature of the output side polarizing plate. Lowering the surface temperature improves the durability of the exit-side polarizing plate. Here, the high transmission polarizing plate having a Tpol-c of 30 to 70% is often used, so that the burden of the high transmission polarizing plate and the output side polarizing plate can be shared almost evenly and the life of both parts can be extended.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, these Examples do not limit this invention.

Example 1
Preparation of a high transmission polarizing plate with a controlled retardation value for G-ch was performed by immersing a polymer film of PVA (manufactured by Kuraray Co., Ltd.) having a polymerization degree of 2,400 and a thickness of 75 μm in warm water at 45 ° C. for 120 seconds. 45 consisting of 100 parts by weight of water, 0.015 parts by weight of CI Direct Orange 39, 0.015 parts by weight of CI Direct Red 79, 0.020 parts by weight of CI Direct Blue 237 and 1.0 part by weight of sodium sulfate. It was immersed in an aqueous solution at 0 ° C. and dyed. Next, the dyed film was uniaxially stretched seven times in a 55 ° C. aqueous solution consisting of 100 parts by weight of water and 4 parts by weight of boric acid, washed with water, dried, and the thickness of the base film was 18 μm. A polarizing element film having a thickness of 550 nm was measured. A TAC film (manufactured by Fuji Film Co., Ltd.) was bonded to both surfaces of the produced polarizing element film to produce a polarizing plate. Further, a hard coat layer was provided on one side. The transmittance of this polarizing plate was measured with a spectrophotometer U-4100 manufactured by Hitachi, Ltd. Tpol-p was 92% and Tpol-c was 32%, and a highly transmissive polarizing plate having high transmittance was obtained.

Comparative Example 1
The basic production procedure is the same as in Example 1, but the polymer film and the retardation value were changed. After immersing a polymer film of PVA (manufactured by Kuraray Co., Ltd.) having a polymerization degree of 4,000 and a thickness of 75 μm in warm water at 45 ° C. for 120 seconds, 100 parts by weight of water, 0.015 parts by weight of CI Direct Orange 39, CI Direct Dyeing was carried out by immersing in an aqueous solution at 45 ° C. consisting of 0.015 parts by weight of red 79 and 0.020 parts by weight of CI direct blue 237 and 1.0 part by weight of sodium sulfate. Next, the dyed film was uniaxially stretched 6 times in a 55 ° C. aqueous solution consisting of 100 parts by weight of water and 3 parts by weight of boric acid, washed with water and dried to have a thickness of 30 μm and a retardation value (Oji A polarizing element film having a thickness of 750 nm was measured. A TAC film (Fuji Film Co., Ltd.) was bonded to both sides of this polarizing element film, and a hard coat layer was provided on the surface of one of the TAC films. A highly transmissive polarizing plate having a Tpol-p of 92% and a Tpol-c of 32% was prepared.

  The transmittance (Tp) between parallel Nicols of a high transmission polarizing plate (Example 1) having a retardation value of 550 nm and a high transmission polarizing plate (Comparative Example 1) having a retardation value of 750 nm using a spectrophotometer U-4100. The transmittance between crossed Nicols (Tc) was measured. Tp is measured by placing two high-contrast polarizing plates on the sample side and the reference side in parallel and calibrating them, and setting the measurement sample in parallel between the base polarizing plates at 0-5 °. The measurement was performed by swinging the optical axis. As a method for measuring Tc, two base-side polarizing plates on the sample side were arranged in an orthogonal position, a measurement sample was arranged between them, and the optical axis was similarly measured from 0 to 5 ° for measurement.

  Table 1 shows the average optical characteristics of Example 1 and Comparative Example 1 between 530 and 580 nm. For a high transmission polarizing plate whose retardation value is controlled to 550 nm, the Tc hardly changes even when the 2 ° optical axis is swung, and the decrease in contrast is not so great. However, for the high transmittance polarizing plate of Comparative Example 1 having a retardation value of 750 nm, the Tc increased 4 times and the contrast also decreased to ¼ even if it was swung by 1 °. In Table 1, the contrast was determined as CR = Tp / Tc.

Example 2 and Comparative Example 2
For the purpose of evaluating the influence on the contrast due to the optical axis angle deviation of the B-ch high transmission polarizing plate, the PVA thickness is 40 μm and the draw ratio is 5.5 times according to the method of Example 1 except for the retardation value. A highly transmissive polarizing plate (Example 2) having a retardation value of 440 nm and a high transmissive polarizing plate (Comparative Example 2) having a PVA thickness of 75 μm and a draw ratio of 6.5 times and a retardation value of 650 nm were prepared. At that time, Tpol-p was 91% and Tpol-c was 32%. About the measurement of Tp and Tc, it measured by the same operation as Example 1 and Comparative Example 1.

  Table 2 shows the average optical characteristics of Example 2 and Comparative Example 2 between 430 and 500 nm. From Table 2, the contrast was good for both samples when there was no deviation of the optical axis angle. However, in Comparative Example 2, it was confirmed that Tc significantly increased and the contrast significantly decreased with the deviation of the optical axis angle. However, in Example 2, when the optical axis was swung from 0 ° to 2 °, the amount of change in Tc was small, and Tc slightly increased when the optical axis was shifted by 3 ° or more. In comparison, it was not so large and the reduction in contrast was suppressed. In Table 2, the contrast value was determined as CR = Tp / Tc. Therefore, the high transmission polarizing plate having the retardation value of Example 2 can suppress the decrease in contrast even when the optical axis angle is shifted by 2 °, and is a highly useful polarizing plate under the B-ch band. is there.

Example 3 and Comparative Example 3
For the purpose of evaluating the influence on the contrast due to the deviation of the optical axis angle of the high transmission polarizing plate for R-ch, except for the retardation value, the PVA thickness was 40 μm and the draw ratio was 5.5 times. A high transmission polarizing plate (Example 3) having a retardation value of 450 nm (Comparative Example 3) and a PVA thickness of 75 μm and a draw ratio of 6.5 times and a retardation value of 640 nm was confirmed. went. At that time, Tpol-p was 91.5% and Tpol-c was 32%. About the measurement of Tp and Tc, it measured by the same operation as Example 1 and Comparative Example 1.

  Table 3 shows the average optical characteristics of Example 3 and Comparative Example 3 between 600 and 640 nm. In Comparative Example 3, it was confirmed that Tc increased as the deviation of the optical axis angle increased, and the contrast was considerably lowered. However, in Example 3, the Tc change amount was still small for the optical axis swung from 0 ° to 2 °, and the Tc increased slightly by shifting the optical axis angle by 3 ° or more. Compared with, it was much smaller and the decrease in contrast was also suppressed considerably. In Table 3, the contrast was determined as CR = Tp / Tc. Therefore, the high transmission polarizing plate having the retardation value of Example 3 is a high transmission polarizing plate useful in the R-ch band because the decrease in contrast is suppressed even when the optical axis angle is shifted by 2 °.

Example 4
A polarizing element film was prepared by the element film preparation method of Example 1 as a highly transmissive polarizing plate for which the retardation value for G-ch was controlled, and a TAC film (manufactured by Fuji Film Co., Ltd.) was bonded to both sides to obtain a retardation value. Was a high transmission polarizing plate of 550 nm. In order to prevent scratches on the polarizing plate surface, a hard coat layer is provided on one side, an AR layer is provided thereon, an adhesive layer is further provided on one side, and the diagonal is cut to a 1-inch size. A sample was prepared by pasting to a glass plate with an AR layer. The optical characteristics of the high-transmitting polarizing plate with a double-sided AR layer were 97% for Tpol-p and 34% for Tpol-c. The high-transmission polarizing plate produced here was incorporated into a liquid crystal projector, and a sample in which the optical axis angle was precisely adjusted and an optical axis shaken by 1 ° were prepared.

Comparative Example 4
A polarizing element film is prepared by the element film preparation method of Comparative Example 1, a TAC film (manufactured by Fuji Film Co., Ltd.) is bonded on both sides, a high-transmission polarizing plate having a retardation value of 750 nm is formed, and a hard coat layer is formed on one side. An AR layer was also provided, and a sample was attached to a glass plate with an AR layer. As a sample preparation, an accurate optical axis and a sample shaken by 1 ° were prepared in the same manner as in Example 4.

  The above samples were prepared and incorporated at the position 12G in FIG. 1 of the liquid crystal projector, and the R and B rays were shielded, and the contrast with only the G rays was examined. The effect of the optical axis misalignment on the G-ch high-transmission polarizing plate on the contrast can be confirmed more accurately by examining only with G rays. The results are shown in Table 4. In the mounting test to be incorporated in the projector, in order to improve the contrast, a contrast improving film (WVA-03B, Fuji Photo Film) between 11 (R, G, B) and 12 (R, G, B) of FIG. What was bonded to the board was incorporated into the projector and a mounting test was conducted.

  For samples with good optical axis accuracy, both samples showed good contrast for the phase difference value of 550 nm controlled for G-ch and uncontrolled 750 nm. However, the sample with a 1 ° optical axis angle showed almost no decrease in contrast in the sample in which the phase difference value was controlled to 550 nm, whereas the sample with a phase difference value of 750 nm was considerably different. A decrease in contrast was confirmed.

  In Example 1 and Comparative Example 1, the contrast of the spectrophotometer was considerably reduced by a slight increase in Tc, but Example 4 in the mounting test incorporated in the projector had a 1 ° optical axis angle. There was almost no reduction in contrast even when shaken. However, in the sample of Comparative Example 1, the contrast in the spectrophotometer is reduced by 3,000 by oscillating the optical axis angle by 1 °, and Comparative Example 4 having the same function as that of this sample is the optical axis in the mounting test. By shaking the angle by 1 °, the contrast was reduced by 150 from the normal contrast. From this result, it was confirmed that the contrast of the high transmission polarizing plate having the G-ch retardation value does not decrease even if the optical axis angle is slightly shifted.

Example 5
According to the methods of Example 1 and Comparative Example 1, a highly transmissive polarizing plate having several levels of retardation value was produced. The production conditions at this time were 40 μm PVA having a degree of polymerization of 2,400, three levels at a draw ratio of 6.0 to 5.5 times, and a draw ratio of 7.0 to 6.5 using 75 μm PVA. Using a PVA of 80 μm having a polymerization degree of 4,000, the draw ratio was set to 2 levels at a 6.0 to 5.7 times. Specifically, the retardation values of the high transmission polarizing plate were 350 nm, 400 nm, 450 nm, 530 nm, 580 nm, 650 nm, 700 nm, and 750 nm. This time, it is produced under these conditions, but the phase difference value also varies depending on the balance between the temperature conditions and the draw ratio. In order to prevent scratches on the polarizing plate surface, a hard coat layer was provided on one side, and an AR layer was also provided. Moreover, in order to confirm the said sample in a mounting test, the sample which shakes the optical axis 0 degree and 1 degree was produced, and also it affixed on the glass plate with AR layer, and produced the sample. This was done to confirm the range that can be used within the G-ch optical wavelength. In order to confirm, the R and B rays are respectively embedded at the position 12G in FIG. 1 of the liquid crystal projector, and the contrast improving film (WVA-03B, Fuji) is placed between 11 and 12 in FIG. A sheet of photographic film) was applied to the substrate, and the contrast with only G rays was examined. The results are shown in Table 5. It was confirmed that the phase difference value of the high-transmission polarizing plate for G-ch was involved in the contrast more accurately by examining only with G rays.

  A slight decrease in contrast is observed when the retardation value is in the range of 400 to 700 nm, but it is not so large and is considered to be within the allowable range. However, a significant reduction in contrast could be confirmed at 350 nm and 750 nm. Therefore, it was confirmed that the range of the retardation value of the green (G-ch) high-transmission polarizing plate is 400 to 700 nm, preferably 450 to 650 nm.

  From such a result, a retardation value of 400 to 700 nm as a high transmission polarizing plate for G-ch is useful, and it is preferable to set the retardation value to 450 to 650 nm.

Example 6
Also in the formula R = nλ ± 100 (n = 2), it was verified by B-ch whether or not the contrast reduction due to the axis deviation was prevented. As a sample, the same PVA as in Comparative Example 1 was used and produced at a draw ratio of 5 times. The retardation value of the highly transmissive polarizing plate at that time was 880 nm, Tpol-p was 90.5%, and Tpol-c was 32%. About the measurement of Tp and Tc, it measured by operation similar to Example 1 and Comparative Example 1, and compared with the value of Example 2 and Comparative Example 2.

In Example 2 which is a high transmission polarizing plate for B-ch, it was found in the examination of Example 2 and Comparative Example 2 that the reduction in contrast can be suppressed even if the optical axis angle is deviated, but the equation R = nλ In Example 6 where ± 100 (n = 2), good results were obtained as in Example 2. As a result, even if n = 2, the ideal phase difference value for each channel can suppress a decrease in contrast even if the optical axis angle is deviated.

It is a figure which shows the structure of a general liquid crystal projector roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... UV and IR cut filter, 3 ... Condensing lens, 4 ... Polarization conversion element, 5, 6 ... Dichroic mirror, 7, 8, 9 ... Total reflection mirror, 10R, 10G, 10B ... Incident side polarization Plate, 11R, 11G, 11B ... Liquid crystal panel, 12R, 12G, 12B ... High transmission polarizing plate, 13B, 13B, 13B ... Emission side polarizing plate, R ... Red light, G ... Green light, B ... Blue light, 14 ... Cross dichroic prism, 15 ... projection lens, 16 ... screen

Claims (10)

In the high transmission polarizing plate provided between the incident side and the outgoing side polarizing plate of the liquid crystal projector, the relationship between the retardation value R (nm) and the wavelength λ (nm) of the light used is R = nλ ± 100 (where A liquid crystal projector using a high transmission polarizing plate, wherein n is an integer 1 or 2). A high transmission polarizing plate for a red channel (R-ch) having a retardation value of 480 to 800 nm or 1,060 to 1,500 nm. A high transmission polarizing plate for a green channel (G-ch) having a retardation value of 400 to 700 nm or 900 to 1,300 nm. A high transmission polarizing plate for a blue channel (B-ch) having a retardation value of 300 to 600 nm or 700 to 1,100 nm. A liquid crystal projector using the high transmission polarizing plate according to any one of claims 2 to 4. A high transmission polarizing plate for red channel (R-ch), green channel (G-ch) and blue channel (B-ch) is provided, and the high transmission polarizing plate for red channel (R-ch) is claimed. The high transmission polarizing plate according to Item 2, the high transmission polarizing plate for green channel (R-ch) is the high transmission polarizing plate according to claim 3, and the high transmission polarizing plate for blue channel (R-ch). The liquid crystal projector according to claim 5, wherein the liquid crystal projector is a high transmission polarizing plate according to item 4. A liquid crystal rear projection television using the liquid crystal projector according to any one of claims 1, 5, and 6. A high transmission polarizing plate for a red channel (R-ch) having a retardation value of 550 to 750 nm or 1,160 to 1,360 nm. A high transmission polarizing plate for a green channel (G-ch) having a retardation value of 450 to 650 nm or 1,000 to 1,200 nm. A high transmission polarizing plate for a blue channel (B-ch) having a retardation value of 350 to 550 nm or 800 to 1,000 nm.

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