JP2012088351A - Intrinsic polarizer, method for manufacturing the same, and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intrinsic polarizer, or a KE polarizer, being suitable for red light; and to provide a method for manufacturing the same and a projector including the intrinsic polarizer.SOLUTION: An intrinsic polarizer 2 includes a polyvinyl alcohol film 200 including vinylene polymer blocks; and comprises a transmission axis for transmitting prescribed linear polarization of incident light, and an absorption axis for absorbing the linear polarization orthogonally crossing with the transmission axis. An average transmittance of the linear polarization orthogonally crossing with the transmission axis of the intrinsic polarizer 2 in a wavelength band of not less than 590 nm but less than 640 nm is 0.03% or less; and an average transmittance of the linear polarization in a wavelength band of not less than 640 nm and not more than 680 nm is less than 1.0%.

Description

  The present invention relates to an intrinsic polarizer, a manufacturing method thereof, and a projector.

  A light modulation device included in a display device or a projector includes an electro-optical device such as a liquid crystal device, and polarizing plates disposed on an incident side and an emission side of the electro-optical device. A polarizing plate used in a display device or a light modulation device includes a dichroic polarizer that transmits linearly polarized light having a predetermined vibration direction and absorbs linearly polarized light having an orthogonal vibration direction among incident light.

  As such a polarizer, for example, an H-type (iodine) polarizer, a dye polarizer, or an intrinsic polarizer (K-type polarizer) is used. H-type polarizers and dye polarizers are polarizers in which a material that becomes a dichroic chromophore such as iodine or a dye is adsorbed on a base material (polymer film), and have low environmental stability. The K-type polarizer is a polarizer that polarizes due to the inherent chemical structure of the base material, and has excellent resistance to temperature and humidity for a long period of time compared to an H-type polarizer and a dye polarizer.

  In recent years, KE type polarizers with improved resistance to temperature and humidity are known for K type polarizers (see, for example, Patent Document 1). By using a polarizing plate provided with a KE-type polarizer, it is possible to further improve the reliability of a light modulation device provided in a display device or a projector that is used in a severe environment such as high temperature and high humidity.

Special table 2008-509433 gazette

  However, the conventional KE type polarizer has a problem that the transmittance of linearly polarized light orthogonal to the transmission axis is higher for red band light than for green band and blue band light. That is, the conventional KE polarizer has a larger amount of linearly polarized light to be absorbed in the red band light than in the green band and blue band light. For this reason, in a configuration such as a projector where light from a light source device is separated into red light, green light, and blue light and modulated by the light modulation device for each color light, the contrast of the red light is that of green light or blue light. The conventional KE type polarizer is not suitable for red light because it is lower than the contrast.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] An intrinsic polarizer according to this application example includes a polyvinyl alcohol film containing a vinylene polymer block, a transmission axis that transmits predetermined linearly polarized light in incident light, and linearly polarized light that is orthogonal to the transmission axis. The average transmittance of linearly polarized light orthogonal to the transmission axis in the wavelength band of 590 nm or more and less than 640 nm is 0.03% or less, and the straight line in the wavelength band of 640 nm or more and 680 nm or less The average transmittance of polarized light is 1.0% or less.

  According to this configuration, the average transmittance of linearly polarized light orthogonal to the transmission axis for light in the wavelength band from 590 nm to 680 nm corresponding to the red band of the intrinsic polarizer is 0.03% or less at 590 nm to less than 640 nm, It is 1.0% or less at 640 nm or more and 680 nm or less. Therefore, since the intrinsic polarizer absorbs linearly polarized light orthogonal to the transmission axis in the red band, it can be suitably used as a polarizer for red light.

  Application Example 2 In the intrinsic polarizer according to the application example described above, it is preferable that an average transmittance of linearly polarized light parallel to the transmission axis in a wavelength band of 590 nm to 680 nm is 85% or more.

  According to this configuration, the average transmittance of linearly polarized light parallel to the transmission axis for light in the wavelength band of 590 nm to 680 nm corresponding to the red band of the intrinsic polarizer is 85% or more. Therefore, the intrinsic polarizer has a brightness suitable as a polarizer for red light.

  Application Example 3 In the intrinsic polarizer according to the application example, the average contrast in the wavelength band of 590 nm to less than 640 nm is 3000: 1 or more, and the average contrast in the wavelength band of 640 nm to 680 nm is 100: 1. The above is preferable.

  According to this configuration, the average contrast for light in the wavelength band of 590 nm to 680 nm corresponding to the red band of the intrinsic polarizer is 3000: 1 or more at 590 nm or more and less than 640 nm, and is 100: 1 or more at 640 nm or more and 680 nm or less. is there. Therefore, the intrinsic polarizer has a contrast suitable as a polarizer for red light.

  Application Example 4 In the intrinsic polarizer according to the application example, the average contrast in the wavelength band of 590 nm to less than 640 nm is 6000: 1 or more, and the average contrast in the wavelength band of 640 nm to 680 nm is 200: 1. The above is preferable.

  According to this configuration, the average contrast for light in the wavelength band from 590 nm to 680 nm corresponding to the red band of the intrinsic polarizer is 6000: 1 or more at 590 nm or more and less than 640 nm, and is 200: 1 or more at 640 nm or more and 680 nm or less. is there. Therefore, the intrinsic polarizer has a better contrast as a polarizer for red light.

  Application Example 5 A method for producing an intrinsic polarizer according to this application example includes an immersion step of immersing a polyvinyl alcohol film in a solution of a dehydration catalyst, dehydrating the polyvinyl alcohol film, and vinylene in the polyvinyl alcohol film. A dehydration step of forming a polymer block; and a stretching step of stretching the polyvinyl alcohol film, wherein the dehydration catalyst contains hydrochloric acid having a concentration of 0.018 N or more and 0.025 N or less.

  According to this configuration, by using a dehydration catalyst containing hydrochloric acid having a concentration of 0.018 N or more and 0.025 N or less, orthogonal to the transmission axis for light in the wavelength band of 590 nm to 680 nm corresponding to the red band. Thus, it is possible to manufacture an intrinsic polarizer in which the average transmittance of the linearly polarized light, the average transmittance of the linearly polarized light parallel to the transmission axis, and the average contrast are in a predetermined range. Therefore, an intrinsic polarizer suitable for red light can be provided.

  Application Example 6 In the method of manufacturing the intrinsic polarizer according to the application example, it is preferable that the dehydration catalyst includes hydrochloric acid having a concentration of 0.021 N or more and 0.025 N or less.

  According to this configuration, by using a dehydration catalyst containing hydrochloric acid having a concentration of 0.021 N or more and 0.025 N or less, a better contrast can be obtained with respect to light in a wavelength band of 590 nm to 680 nm corresponding to the red band. It is possible to manufacture an intrinsic polarizer having the same.

  Application Example 7 A projector according to this application example includes a light source device, a light modulation device that modulates light from the light source device, and a projection optical device that projects light from the light modulation device. The light modulation device corresponds to each color light of red light, green light, and blue light, and a pair of polarizing plates disposed on the incident side and the emission side of the electro-optical device. And at least one of the pair of polarizing plates corresponding to the red light includes any one of the intrinsic polarizers.

  According to this configuration, at least one of the pair of polarizing plates of the light modulation device corresponding to red light includes the intrinsic polarizer that is superior in heat resistance and moisture resistance as compared with the conventional polarizer. For this reason, since the deterioration of the characteristics of the light modulation device can be suppressed over a long period of time, a highly reliable projector can be provided.

  Application Example 8 In the projector according to the application example, the polarizing plate disposed on at least the emission side of the pair of polarizing plates corresponding to the red light includes the intrinsic polarizer. It is preferable.

  According to this configuration, at least the polarizing plate on the exit side of the electro-optical device includes the intrinsic polarizer that is superior in heat resistance and moisture resistance as compared with the conventional polarizer. Since the temperature on the emission side of the electro-optical device is higher than that on the incident side, the characteristic deterioration of the light modulation device can be effectively suppressed.

The schematic diagram which shows schematic structure of the polarizing plate which concerns on this embodiment. The graph which shows the polarization characteristic of the intrinsic | native polarizer which concerns on this embodiment. The flowchart which shows the manufacturing method of the polarizer which concerns on this embodiment. The schematic diagram which shows the manufacturing method of the polarizer which concerns on this embodiment. The graph which shows the relationship between hydrochloric acid concentration and orthogonal transmittance | permeability. The graph which shows the relationship between hydrochloric acid concentration and parallel transmittance | permeability. The graph which shows the relationship between hydrochloric acid concentration and contrast. 1 is a schematic diagram showing a schematic configuration of a projector according to an embodiment.

  An embodiment of the present invention will be described below with reference to the drawings. In each of the drawings to be referred to, the dimensional ratios, angles, and the like of the respective constituent elements are appropriately changed for easy understanding of the configuration.

<Configuration of polarizing plate>
First, a schematic configuration of the polarizing plate according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram illustrating a schematic configuration of a polarizing plate according to the present embodiment. Specifically, FIG. 1A is a schematic diagram of a polarizing plate provided with an intrinsic polarizer according to the present embodiment, and FIG. 1B is a schematic diagram of a polarizing plate provided with a conventional intrinsic polarizer as a comparison. FIG. 1C is a schematic diagram of a polarizing plate provided with a polarizer such as an H-type polarizer or a dye polarizer as a comparison.

  FIG. 2 is a graph showing the polarization characteristics of the intrinsic polarizer according to this embodiment. Specifically, FIG. 2 (a) is a graph showing the transmittance of linearly polarized light orthogonal to the transmission axis of the intrinsic polarizer, and FIG. 2 (b) shows the transmittance of linearly polarized light parallel to the transmission axis of the intrinsic polarizer. FIG. 2C is a graph showing the contrast of the intrinsic polarizer. 2A, 2B, and 2C show the polarization characteristics of the intrinsic polarizer 2 in comparison with the polarization characteristics of the intrinsic polarizer 5 that is a conventional KE polarizer.

  As shown in FIG. 1A, the polarizing plate 1 according to this embodiment includes an intrinsic polarizer 2 and a support layer 3. The intrinsic polarizer 2 is a so-called KE polarizer including a film of polyvinyl alcohol (Poly Vinyl Alcohol: PVA) containing a vinylene polymer block (a block copolymer of vinyl alcohol and vinylene). The intrinsic polarizer 2 has a transmission axis that transmits predetermined linearly polarized light in incident light, and an absorption axis that absorbs linearly polarized light orthogonal to the transmission axis. The thickness of the intrinsic polarizer 2 is, for example, about 5 μm to 100 μm.

  As represented by the following chemical formula, PVA, which is a base material of the intrinsic polarizer 2, is a polymer compound obtained by hydrolysis of polyvinyl acetate and has a hydroxyl group. The intrinsic polarizer 2 is obtained by forming a vinylene polymer block serving as a dichroic chromophore in the base material by adding hydrogen to the hydroxyl group of PVA and performing a dehydration treatment.

  The polarizing plate 4 shown in FIG. 1B includes an intrinsic polarizer 5 that is a conventional KE type polarizer and a support layer 3. The intrinsic polarizer 5 includes a PVA film containing a vinylene polymer block as in the intrinsic polarizer 2, but the vinylene polymer block content is less than that of the intrinsic polarizer 2.

  The intrinsic polarizer 2 is a polarizer for use for red light. A polarizer used for red light is required to have good polarization characteristics for light in a wavelength band corresponding to the red band, for example, a wavelength band of 590 nm to 680 nm. Since the polarization characteristics vary depending on the wavelength band of light, as described below, the fact that the average value of the polarization characteristics within the above-mentioned wavelength band is within a predetermined range can be used for red light. Conditions that can be used.

  Regarding the transmittance of linearly polarized light orthogonal to the transmission axis shown in FIG. 2A (hereinafter referred to as orthogonal transmittance), the average orthogonal transmittance in the wavelength band of 590 nm or more and less than 640 nm is 0.03% or less. The average orthogonal transmittance in the wavelength band of 640 nm to 680 nm is preferably 1.0% or less. In this wavelength band, the orthogonal transmittance of the intrinsic polarizer 2 is within the predetermined range described above. On the other hand, the orthogonal transmittance of the intrinsic polarizer 5 is larger than the orthogonal transmittance of the intrinsic polarizer 2 in the wavelength band of 590 nm or more and 680 nm or less, and exceeds a predetermined range. If the orthogonal transmittance is large, the amount of transmission of linearly polarized light to be absorbed increases, leading to a decrease in contrast.

  Regarding the transmittance of linearly polarized light parallel to the transmission axis shown in FIG. 2B (hereinafter referred to as parallel transmittance), the average parallel transmittance in the wavelength band of 590 nm to 680 nm may be 85% or more. desirable. In this wavelength band, the average parallel transmittances of the intrinsic polarizer 2 and the intrinsic polarizer 5 are both predetermined 85% or more, and there is no significant difference between the two.

  Regarding the contrast shown in FIG. 2C, the average contrast in the wavelength band of 590 nm to less than 640 nm is preferably 3000: 1 or more, and the average contrast in the wavelength band of 640 nm to 680 nm is preferably 100: 1 or more. In this wavelength band, the average contrast of the intrinsic polarizer 2 is in a predetermined range, but the average contrast of the intrinsic polarizer 5 is lower than the average contrast of the intrinsic polarizer 2 and is near the lower limit of the prescribed range.

  Thus, the intrinsic polarizer 5, which is a conventional KE polarizer, is not suitable as a polarizer for red light because of its low polarization characteristics with respect to light in the red band, and is generally used for red light. There wasn't. The intrinsic polarizer 2 has better polarization characteristics with respect to light in the red band than the intrinsic polarizer 5, and can be suitably used as a polarizer for red light. The difference in polarization characteristics between the intrinsic polarizer 2 and the intrinsic polarizer 5 results from the difference in the content of the vinylene polymer block. That is, the intrinsic polarizer 2 contains more vinylene polymer blocks than the intrinsic polarizer 5, and thus has a lower orthogonal transmittance for red band light.

  2A, 2B, and 2C, the graph of the intrinsic polarizer 2 is obtained when the concentration of hydrochloric acid in the dehydration catalyst in Step S1 of the polarizer manufacturing method described later is 0.018N. The average value of the samples. Further, the graph of the polarization characteristics of the intrinsic polarizer 5 is the average value of the sample when the concentration of hydrochloric acid in the dehydration catalyst is 0.014N.

  Returning to FIG. 1A, the support layer 3 is for protecting the intrinsic polarizer 2 from external mechanical stress and dirt. The support layer 3 is made of, for example, a material such as triacetyl cellulose (TAC). The material of the support layer 3 may be a resin material such as polycarbonate, polyacrylate, polypropylene, or polyethylene terephthalate, or may be an inorganic material such as quartz, glass, sapphire, or quartz. The thickness of the support layer 3 is, for example, about 10 μm to 1000 μm.

  Incidentally, since the base material (PVA or the like) is water-soluble, the H-type polarizer and the dye polarizer are likely to be distorted and deformed depending on environmental conditions such as temperature and humidity, and the polarization characteristics are likely to deteriorate. Therefore, as shown in FIG. 1C, a polarizing plate 6 having a polarizer 7 such as an H-type polarizer or a dye polarizer generally has a pair of support layers 8a made of TAC or the like on both sides of the polarizer 7. Although it has the structure pinched | interposed by 8b, compared with the polarizing plates 1 and 4 provided with the intrinsic polarizers 2 and 5 still, stability with respect to an environment is low.

  The polarizing plate 1 may further include an optical element layer having a phase difference, wavelength selectivity, an antireflection layer, or the like on the support layer 3 or on the side opposite to the support layer 3 of the intrinsic polarizer 2. . The polarizing plate 1 further includes a layer and a release film for protecting the intrinsic polarizer 2 from mechanical stress and dirt from the outside, like the supporting layer 3, on the opposite side of the intrinsic polarizer 2 from the support layer 3. It may be.

  As described above, the polarizing plate 1 including the intrinsic polarizer 2 according to the present embodiment has environmental stability compared to the polarizing plate 6 including the polarizer 7 such as an H-type polarizer or a dye polarizer. High and little deterioration of polarization characteristics. Furthermore, the polarizing plate 1 can be suitably used as a polarizing plate for red light, which is not suitable for the polarizing plate 4 provided with the intrinsic polarizer 5 which is a conventional KE type polarizer.

<Method for producing polarizer>
Next, a method for manufacturing a polarizer according to the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing a method for manufacturing a polarizer according to this embodiment. FIG. 4 is a schematic diagram showing a method for manufacturing a polarizer according to this embodiment.

  As shown in FIG. 3, the manufacturing method of the polarizer according to this embodiment includes a first immersion process (step S1), a first stretching process (step S2), a dehydration process (step S3), 2 stretching step (step S4) and a second dipping step (step S5). The method for manufacturing a polarizer according to this embodiment is substantially the same as the method for manufacturing a conventional KE polarizer except that the concentration of hydrochloric acid in the first immersion step (step S1) is different.

  As shown in FIG. 4, in the method for manufacturing a polarizer according to this embodiment, a PVA film 200 that is a base material of the intrinsic polarizer 2 is supplied from one side in a state of being wound around a roll, for example, and continuously. In this state, processing in each process is performed, and the other side is wound up on a roll again.

  In step S1, the PVA film 200 is immersed in a solution 210 of dehydration catalyst. The dehydration catalyst contains hydrochloric acid having a concentration of 0.018 N or more and 0.025 N or less. By dipping in the dehydration catalyst solution 210, hydrogen (H) is added to the hydroxyl group (OH) of PVA in the PVA film 200. In step S1, the higher the concentration of hydrochloric acid in the dehydration catalyst, the greater the amount of hydrogen added to the hydroxyl group of PVA, and the more dehydration of PVA is performed in step S3.

  In step S2, the PVA film 200 is stretched. By extending | stretching, the directionality of the vinylene polymer block in the PVA film 200 is arrange | equalized, and a polarization characteristic is added. Step S2 can be performed before, during, after, or before and after step S1.

  Next, in step S3, the PVA film 200 is heated by heating means 220 such as an IR lamp, for example. By heating, the hydroxyl group (OH) and hydrogen (H) of PVA are combined and evaporated to be dehydrated. And the vinylene polymer block (block copolymer of vinyl alcohol and vinylene) which becomes a dichroic chromophore is formed in the PVA film 200 by dehydration. Formation of the vinylene polymer block in the PVA film 200 is also referred to as conversion of the PVA film 200. In step S3, the more PVA is dehydrated, the more vinylene polymer block is formed. Therefore, the amount of the vinylene polymer block formed in step S3 increases as the concentration of hydrochloric acid in the dehydration catalyst in step S1 increases.

  In step S4, the PVA film 200 is stretched. By stretching, the directionality of the vinylene polymer block in the PVA film 200 is further aligned, and a polarization characteristic having a transmission axis and an absorption axis is added by the formed vinylene polymer block. Step S4 can be performed before, during, after, or before and after step S3.

  Next, in step S5, the PVA film 200 is immersed in the boric acid solution 230. By immersing in the boric acid solution 230, a crosslinked structure of PVA is formed in the PVA film 200. Thereby, the intensity | strength of the PVA film 200 increases.

  After step S5, the PVA film 200 is washed and dried to obtain a continuous film-like intrinsic polarizer 2 (PVA film 200). A polarizing plate 1 is obtained by attaching a support layer 3 to the intrinsic polarizer 2. In each step from Step S1 to Step S5, as the conditions other than the concentration of hydrochloric acid in the dehydration catalyst in Step S1, known conditions such as the conditions described in Patent Document 1 can be applied.

  Although not shown in the figure, the continuous film-like support layer 3 (TAC) is bonded to the continuous film-like intrinsic polarizer 2 (PVA film 200) before being wound on the roll after step S5. May be. Similarly, a release film or the like may be bonded to the continuous film-like intrinsic polarizer 2 (PVA film 200) before being wound on the roll after step S5.

<Hydrochloric acid concentration in dehydration catalyst>
Here, the concentration of hydrochloric acid in the dehydration catalyst in step S1 will be described in detail. Patent Document 1 describes that the concentration of hydrochloric acid in the dehydration catalyst is 0.01 N to 4.0 N. As described above, the higher the concentration of hydrochloric acid in the dehydration catalyst, the greater the amount of vinylene polymer block formed, but the greater the amount of vinylene polymer block formed, the greater the hardness of the PVA film 200. If the concentration of hydrochloric acid exceeds 0.025 N, the hardness of the PVA film 200 increases and stretching becomes difficult, so that the orientation of the vinylene polymer block is difficult to align and the orientation becomes insufficient. As a result, both the orthogonal transmittance and the parallel transmittance of the polarizer are lowered. Further, if the PVA film 200 is forcibly stretched in a state where stretching is difficult, wrinkles and streaks and film breakage occur. Accordingly, when the concentration of hydrochloric acid exceeds 0.025N, the quality of the obtained polarizer is significantly deteriorated.

  Conventional KE polarizers such as the intrinsic polarizer 5 are generally manufactured in a low concentration range where the concentration of hydrochloric acid is, for example, 0.014 N or less. However, when the concentration of hydrochloric acid is low, the amount of vinylene polymer block formed is small, and therefore the polarization characteristic for light in the red band is low. Therefore, the conventional KE type polarizer such as the intrinsic polarizer 5 is not suitable as a polarizer for red light. On the other hand, in the manufacturing method of the polarizer of the present embodiment, the concentration of hydrochloric acid in the dehydration catalyst is in the range of 0.018 N or more and 0.025 N or less, which is suitable for red band light. An intrinsic polarizer 2 having polarization characteristics can be manufactured.

  Next, the relationship between the hydrochloric acid concentration in the dehydration catalyst in step S1 and the polarization characteristics of the intrinsic polarizer obtained as a result will be described with reference to FIGS. 5, 6, and 7. FIG. FIG. 5 is a graph showing the relationship between hydrochloric acid concentration and orthogonal transmittance. FIG. 6 is a graph showing the relationship between hydrochloric acid concentration and parallel transmittance. FIG. 7 is a graph showing the relationship between hydrochloric acid concentration and contrast.

  In the following description, the polarized light that can be used for red light that the average value of the polarization characteristics in the wavelength band corresponding to the red band described in the configuration of the polarizing plate is within a predetermined range. It is a child condition.

  FIG. 5A shows the average orthogonal transmittance in the wavelength band of 590 nm or more and less than 640 nm for the intrinsic polarizer produced by varying the hydrochloric acid concentration in the dehydration catalyst. The measured value of each intrinsic polarizer is indicated by dots, and the approximate curve based on the measured values and the upper side of the 95% confidence interval estimated from the t distribution are indicated by broken lines. 5B shows the average orthogonal transmittance in the wavelength band of 640 nm or more and 680 nm or less in the same manner as FIG. 5A.

  As shown in FIG. 5A, if the concentration of hydrochloric acid in the dehydration catalyst is in the range of 0.018 to 0.025 N, the average orthogonal transmittance in the wavelength band of 590 to 640 nm is 95% reliable. Even on the upper side of the section, it is 0.03% or less. However, if the hydrochloric acid concentration is less than 0.018 normal, the average orthogonal transmittance exceeds 0.03% on the upper side of the 95% confidence interval.

  Further, as shown in FIG. 5B, when the hydrochloric acid concentration in the dehydration catalyst is in the range of 0.018 to 0.025 N, the average orthogonal transmittance in the wavelength band of 640 to 680 nm is 95. It is 1.0% or less even above the% confidence interval. However, if the hydrochloric acid concentration is less than 0.018 normal, the average orthogonal transmittance exceeds 1.0% above the 95% confidence interval.

  Next, FIG. 6 shows the average parallel transmittance in the wavelength band of 590 nm or more and 680 nm or less for the intrinsic polarizer manufactured by varying the hydrochloric acid concentration in the dehydration catalyst. The measured values of each intrinsic polarizer are indicated by dots, and the approximate curve based on the measured values and the upper and lower sides of the 95% confidence interval estimated from the t distribution are indicated by broken lines.

  As shown in FIG. 6, if the concentration of hydrochloric acid in the dehydration catalyst is in the range of 0.018 to 0.025 N, the average parallel transmittance in the wavelength band of 590 to 680 nm is below the 95% confidence interval. Also on the side, it is 85% or more. However, if the hydrochloric acid concentration exceeds 0.025N, the average parallel transmittance falls below 85% below the 95% confidence interval.

  Next, FIG. 7 (a) shows the contrast in the wavelength band of 590 nm or more and less than 640 nm for the intrinsic polarizer produced by varying the hydrochloric acid concentration in the dehydration catalyst. The measured values of each intrinsic polarizer are indicated by dots, and the approximate curve based on the measured values and the upper and lower sides of the 95% confidence interval estimated from the t distribution are indicated by broken lines. FIG. 7B shows the contrast in the wavelength band of 640 nm to 680 nm in the same manner as FIG.

  As shown in FIG. 7 (a), if the concentration of hydrochloric acid in the dehydration catalyst is in the range of 0.018 or more and 0.025 or less, the contrast in the wavelength band of 590 to 640 nm is below the 95% confidence interval. Also on the side, it is 3000: 1 or more. However, if the hydrochloric acid concentration is less than 0.018 normal, the contrast is below 3000: 1 at the lower side of the 95% confidence interval.

  In addition, as shown in FIG. 7B, when the hydrochloric acid concentration in the dehydration catalyst is in the range of 0.018 to 0.025, the contrast in the wavelength band of 640 to 680 nm is 95% confidence interval. Also on the lower side, it becomes 100: 1 or more. However, if the hydrochloric acid concentration is less than 0.018 normal, the contrast is less than 100: 1 at the lower side of the 95% confidence interval.

  Here, when the hydrochloric acid concentration in the dehydration catalyst is in the range of 0.021 N or more and 0.025 N or less, the contrast in the wavelength band of 590 nm or more and less than 640 nm shown in FIG. In FIG. 7B, the contrast in the wavelength band of 640 nm to 680 nm is 200: 1 or more below the 95% confidence interval. Therefore, by setting the hydrochloric acid concentration in the dehydration catalyst in the range of 0.021 N or more and 0.025 N or less, the intrinsic polarizer 2 having higher contrast in the red light wavelength band can be manufactured.

  On the other hand, when the hydrochloric acid concentration in the dehydration catalyst is in the range of 0.018 N or more and less than 0.021 N, the contrast is higher in the wavelength band of 590 nm or more and less than 640 nm compared to the case of 0.021 N or more and 0.025 N or less. However, the parallel transmittance shown in FIG. 6 is increased. When the parallel transmittance is high, the amount of light transmitted in the wavelength band of red light increases, so that when used for a polarizing plate of a display device or a projector, a brighter image display can be obtained.

  As described above, according to the method for manufacturing a polarizer according to the present embodiment, the hydrochloric acid concentration in the dehydration catalyst is in the range of 0.018 N or more and 0.025 N or less, which is suitable for red light. An intrinsic polarizer 2 can be provided. Furthermore, by providing the concentration of hydrochloric acid in the dehydration catalyst in the range of 0.018 or more and less than 0.021 normal, the intrinsic polarizer 2 suitable for applications in which brightness is important in the wavelength band of red light is provided. In the range of 0.021 or more and 0.025 or less, the intrinsic polarizer 2 suitable for applications in which contrast is important in the wavelength band of red light can be provided.

<Configuration of projector>
Next, a schematic configuration of the projector according to the present embodiment will be described with reference to FIG. FIG. 8 is a schematic diagram showing a schematic configuration of the projector according to the present embodiment. The projector 100 is an electronic device that modulates a light beam emitted from a light source according to image information and enlarges and projects it on a projection surface such as a screen.

  As shown in FIG. 8, the projector 100 includes an exterior case 101, a light source device 10, an illumination optical device 20, a color separation optical device 30, a relay optical device 40, a light modulation device 50, and a projection optical device 60. And. The light source device 10, the illumination optical device 20, the color separation optical device 30, the relay optical device 40, the light modulation device 50, and the projection optical device 60 are housed and fixed in the exterior case 101.

  The light source device 10 includes an arc tube 11 that emits a light beam and a reflector 12. The arc tube 11 is composed of an ultra-high pressure mercury lamp, a metal halide lamp, or the like. The light source device 10 reflects the light beam emitted from the arc tube 11 by the reflector 12 to align the emission direction, and emits the light toward the illumination optical device 20. The illumination optical axis OC is the central axis of the light beam emitted from the light source device 10 toward the illuminated area.

  The illumination optical device 20 includes a first lens array 21, a second lens array 22, a polarization conversion element 23, and a superimposing lens 24. The illumination optical device 20 divides the light beam emitted from the light source device 10 into a plurality of partial light beams, aligns each partial light beam with approximately one type of polarized light, and three liquid crystal devices 52R, 52G, and 52B that are illumination targets. Are superimposed on the light incident surface.

  The color separation optical device 30 includes a first dichroic mirror 31, a second dichroic mirror 32, and a reflection mirror 33. The color separation optical device 30 separates the light beam emitted from the illumination optical device 20 into three color lights of red (R) light, green (G) light, and blue (B) light.

  The relay optical device 40 includes an incident side lens 41, a relay lens 42, and reflection mirrors 43 and 44. The relay optical device 40 guides the B light separated by the color separation optical device 30 to the liquid crystal device 52B for B light. In the present embodiment, the relay optical device 40 is configured to guide the B light. However, the present invention is not limited to this. For example, the relay optical device 40 may be configured to guide the R light.

  The light modulation device 50 includes field lenses 51R, 51G, and 51B corresponding to the three color lights of R, G, and B, incident-side polarizing plates 53R, 53G, and 53B disposed on the light incident side, and electro-optics. The liquid crystal devices 52R, 52G, and 52B as devices, the emission side polarizing plates 54R, 54G, and 54B arranged on the light emission side, and the respective color lights emitted from the emission side polarizing plates 54R, 54G, and 54B are incident. The cross dichroic prism 55 is provided.

  The incident-side polarizing plates 53R, 53G, and 53B and the emission-side polarizing plates 54R, 54G, and 54B are, for example, arranged in crossed Nicols so that their transmission axes are orthogonal to each other. A polarizing plate 1 (inherent polarizer 2) is provided as the incident side polarizing plate 53R for red light and the outgoing side polarizing plate 54R, and incident side polarizing plates 53G and 53B for green light and blue light and an outgoing side polarizing plate 54G. , 54B includes a polarizing plate 4 (inherent polarizer 5).

  The liquid crystal devices 52R, 52G, and 52B modulate each color light separated by the color separation optical device 30 according to image information. The cross dichroic prism 55 has a substantially square shape in plan view in which four right angle prisms are bonded together, and two dielectric multilayer films are formed on the interface where the right angle prisms are bonded together. The cross dichroic prism 55 combines the color lights modulated by the liquid crystal devices 52R, 52G, and 52B, and emits the light to the projection optical device 60 side.

  The projection optical device 60 includes a plurality of lenses and a cylindrical lens barrel that houses the plurality of lenses therein (specific illustration is omitted). The projection optical device 60 emits the light beam modulated and synthesized by the light modulation device 50 onto a projection surface such as a screen. As a result, the image is enlarged and projected on the projection surface.

  Incidentally, the incident-side polarizing plates 53R, 53G, and 53B and the emission-side polarizing plates 54R, 54G, and 54B are heated to high temperatures when the light beams from the light source device 10 are incident thereon, and are exposed to various environments depending on the place where the projector 100 is used. Therefore, it is desirable to have high stability with respect to the environment.

  However, in a conventional projector provided with a polarizing plate 6 (a polarizer 7 such as an H-type polarizer or a dye polarizer) as an entrance-side polarizer and an exit-side polarizer for each of the three colors, the environment of the polarizer 7 The polarization characteristics were easily deteriorated. In addition, since the polarizing plate 6 includes a pair of support layers 8a and 8b on both sides of the polarizer 7 (see FIG. 1C), an incident-side polarizer 7 and an exit-side polarizer 7 for each color light. One of the support layers 8a and 8b is interposed on both sides between the two. Since the support layers 8a and 8b made of TAC or the like have a phase difference, the light transmitted through the incident-side polarizer 7 and the exit-side polarizer 7 is disturbed, and as a result, the polarization characteristics are degraded. These have been one of the factors that hinder the improvement in projector characteristics and reliability.

  In order to improve such a situation, a projector having an intrinsic polarizer 5 which is a KE type polarizer having high stability with respect to the environment and whose polarization characteristics are hardly deteriorated has appeared. However, in such a projector, since the polarizing plate 4 (the intrinsic polarizer 5) is not suitable as a polarizing plate for red light, the polarizing plate 4 is used as a polarizing plate for green light and blue light, and for red light. In many cases, the polarizing plate 6 was used as the polarizing plate. For this reason, the effect of improving the characteristics and improving the reliability is limited to green light and blue light, and also causes color unevenness in an image projected by combining R, G, and B color lights.

  In contrast, the projector 100 according to the present embodiment includes the polarizing plate 1 (inherent polarizer 2) as the incident-side polarizing plate 53R for red light and the emitting-side polarizing plate 54R, and is used for green light and blue light. A polarizing plate 4 (inherent polarizer 5) is provided as the incident side polarizing plates 53G and 53B and the exit side polarizing plates 54G and 54B. Therefore, the projector 100 can improve characteristics and reliability as compared with the conventional projector described above, and can also improve the quality of the projected image.

  In the polarizing plates 1 and 4, the support layer 3 is provided on one side of the intrinsic polarizers 2 and 5 (see FIGS. 1A and 1B). Therefore, if the incident-side and emission-side polarizing plates 1 and 4 are arranged so that the support layer 3 is on the outer side, the incident-side intrinsic polarizers 2 and 5 and the exit-side intrinsic polarizers 2 and 5 are disposed. The support layer 3 is not interposed. Accordingly, it is possible to avoid the disturbance of light transmitted through the incident-side intrinsic polarizers 2 and 5 and the exit-side intrinsic polarizers 2 and 5 due to the support layer 3 being interposed.

(Modification 1)
In the above embodiment, the projector 100 has been described as an electronic apparatus including the polarizing plate 1 (inherent polarizer 2). However, the polarizing plate 1 (inherent polarizer 2) has a red band in not only the projector but also a display device. It can be suitably used as a polarizing plate (polarizer) for light.

(Modification 2)
The projector 100 in the above embodiment includes the polarizing plate 1 (inherent polarizer 2) in both the incident-side polarizing plate 53R and the emitting-side polarizing plate 54R for red light, but the present invention is limited to such a form. Not. It is good also as a structure provided with the polarizing plate 1 (intrinsic polarizer 2) in any one of the incident side polarizing plate 53R for red light, and the exit side polarizing plate 54R.

  Since the red light has a smaller light energy than the green light and the blue light, the influence of the temperature is relatively small. Therefore, a configuration in which one of the incident-side polarizing plate 53R and the exit-side polarizing plate 54R for red light includes the polarizing plate 1 (inherent polarizer 2) and the other includes the polarizing plate 6 (polarizer 7). Compared with the case where both have polarizing plates 6 (polarizers 7), deterioration of characteristics and deterioration of reliability are suppressed. In this case, since the temperature of the exit-side polarizing plate 54R is higher than that of the incident-side polarizing plate 53R, the exit-side polarizing plate 54R is preferably provided with the polarizing plate 1 (inherent polarizer 2).

(Modification 3)
The projector 100 in the above embodiment is a transmissive projector that includes a transmissive liquid crystal device 52 that transmits light and has a light beam incident surface and a light beam emission surface different from each other. However, the present invention is not limited to this. . The projector may be a reflective projector that includes a reflective liquid crystal device that reflects light and has the same light incident surface and light exit surface. Even when the present invention is applied to a reflective projector, the same effect as that of a transmissive projector can be obtained.

(Modification 4)
The projector according to the above embodiment includes the light-side modulation apparatus including the incident-side polarizing plates 53R, 53G, and 53B and the emission-side polarizing plates 54R, 54G, and 54B for the three color lights of R, G, and B. It is not limited to such a form. The present invention can also be applied to a projector including, for example, one, two, or four or more incident-side polarizing plates and emitting-side polarizing plates for red light including red light.

  DESCRIPTION OF SYMBOLS 1,4 ... Polarizing plate, 2,5 ... Intrinsic polarizer, 10 ... Light source device, 50 ... Light modulation device, 52 ... Liquid crystal device as an electro-optical device, 53R, 53G, 53B ... Incident as a pair of polarizing plates Side polarizing plate, 54R, 54G, 54B... Exit side polarizing plate as a pair of polarizing plates, 60... Projection optical device, 100.

Claims (8)

Including a polyvinyl alcohol film containing a vinylene polymer block;
A transmission axis that transmits predetermined linearly polarized light of incident light, and an absorption axis that absorbs linearly polarized light orthogonal to the transmission axis;
The average transmittance of linearly polarized light orthogonal to the transmission axis in the wavelength band of 590 nm or more and less than 640 nm is 0.03% or less, and the average transmittance of the linearly polarized light in the wavelength band of 640 nm or more and 680 nm or less is 1.0% or less. The intrinsic polarizer characterized by being. The intrinsic polarizer according to claim 1, wherein
An intrinsic polarizer, wherein an average transmittance of linearly polarized light parallel to the transmission axis in a wavelength band of 590 nm or more and 680 nm or less is 85% or more. The intrinsic polarizer according to claim 1 or 2,
An intrinsic polarizer, wherein an average contrast in a wavelength band of 590 nm or more and less than 640 nm is 3000: 1 or more, and the average contrast in a wavelength band of 640 nm or more and 680 nm or less is 100: 1 or more. The intrinsic polarizer according to claim 3, wherein
An intrinsic polarizer, wherein an average contrast in a wavelength band of 590 nm or more and less than 640 nm is 6000: 1 or more, and the average contrast in a wavelength band of 640 nm or more and 680 nm or less is 200: 1 or more. An immersion step of immersing the polyvinyl alcohol film in a solution of the dehydration catalyst;
Dehydrating the polyvinyl alcohol film to form a vinylene polymer block in the polyvinyl alcohol film; and
Stretching step of stretching the polyvinyl alcohol film,
The method for producing an intrinsic polarizer, wherein the dehydration catalyst contains hydrochloric acid having a concentration of 0.018 N or more and 0.025 N or less. A method for producing the intrinsic polarizer according to claim 5,
The method for producing an intrinsic polarizer, wherein the dehydration catalyst contains hydrochloric acid having a concentration of 0.021 N or more and 0.025 N or less. A projector comprising: a light source device; a light modulation device that modulates light from the light source device; and a projection optical device that projects light from the light modulation device,
The light modulation device includes an electro-optical device and a pair of polarizing plates disposed on the incident side and the emission side of the electro-optical device corresponding to each color light of red light, green light, and blue light,
5. The projector according to claim 1, wherein at least one of the pair of polarizing plates corresponding to the red light includes the intrinsic polarizer according to claim 1. The projector according to claim 7, wherein
Of the pair of polarizing plates corresponding to the red light, at least the polarizing plate disposed on the emission side includes the intrinsic polarizer.

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