• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
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    • 专利摘要:
    A polarization beam splitter (12) comprising: a first prism (21); a second prism (22); a polarization beam splitting portion (26) in contact with the second prism (22); a substrate (23) disposed between the polarization beam splitting portion (26) and the first prism (21); a first adhesive portion (24) disposed between the first prism and the substrate; and a second adhesive portion (25) disposed between the polarization beam splitting portion (26) and the substrate (23).
    公开号:FR3072187A1
    申请号:FR1858701
    申请日:2018-09-25
    公开日:2019-04-12
    发明作者:Yuuki MAEDA
    申请人:Canon Inc；
    IPC主号:
    专利说明:

    BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a polarization beam splitter and an image projection apparatus using it.
    Description of the Related Art [0002] A polarization beam splitter described in the Japanese patent application published before examination No. 2015-45725 is known in. as a polarization beam splitter for an image projection apparatus using, a refractive optical modulation portion. The polarization beam splitter described in the Japanese patent application published before examination n ° 2015-45725 has a structure in which two parallel flat blades provided with a polarizing beam splitting film, between them are sandwiched in pairs prisms. The two parallel flat blades are made of spinel, a material having a high thermal conductivity, In other words, the polarization beam splitter described in the Japanese patent application published before examination no 20.1.5-4 5725 is capable of suppressing an increase in temperature of the polarizing beam splitting film by sandwiching the polarizing beam dividing film. by back parallel flat blades made of a material with high thermal conductivity, it is therefore possible to suppress a temperature distribution generated by the absorption of film light, polarizing beam division, and thus to suppress a black floating and a irregularity of colors, which are generated by the disturbance of polarisati.cn caused by birefringence which can be attributed to the internal stress generated by this temperature distribution.
    Here we consider a case in which the polarization beam splitter described in the Japanese patent application published before examination No. 2015-45725 is. arranged inside an image projection apparatus so that light from a refractive optical modulation portion is reflected by the polarization beam splitter for guidance in an optical projection system. In this case, if the material of the parallel flat blades and the material of the prisms have high refractive indices, the light guided in the projection optical system is influenced by the difference in refractive index between the material of the parallel flat blades and the prism material, possibly increasing the aberration and thus leading to a deterioration in the image quality of the projected image.
    SUMMARY OF THE INVENTION
    In this regard, the present invention aims to provide a polarization beam splitter capable of removing more than ever an influence of the polarization beam splitter on an image quality while suppressing an increase in temperature. a polarization beam splitting part, and an image projection apparatus using the polarization beam splitter.
    To achieve the object described above, a polarization beam splitter according to the present invention comprises: a first prism; a second prism; a polarization beam splitting portion in contact with the second prism; a substrate disposed between the polarization beam splitting portion and the first prism; a first adhesive portion disposed between the first prism and the substrate; and a second adhesive portion disposed between the polarization beam dividing portion and the substrate. Furthermore, to achieve the object described above, an image projection apparatus according to the present invention comprises: a light source part adapted to. emitting light containing a first beam of colored light, a second beam of colored light and a third beam of colored light which have different wavelengths from each other; the polarization beam splitter described above; a refractive optical modulation part; and a holding part adapted to hold a projection optical system which guides light coming from the refractive optical modulation part towards a projection surface, the polarization beam splitter being arranged so that. light from the light source portion passes through the polarization beam splitter and is incident on the refractive optical modulation portion, and the light modulated by the refractive optical modulation portion is reflected by the polarization beam splitter.
    Other features of the present invention will become apparent from the following description of embodiments given by way of example in conjunction with the accompanying drawings.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Figure 1 is. a diagram representing a configuration of an image projection apparatus according to a first embodiment.
    Figure 2 is a diagram showing a configuration of a polarization beam splitter 12 according to the first embodiment.
    Figures 3A and 3B are diagrams showing a direction of a slow axis of a substrate 2 3 according to the first embodiment.
    FIG. 4 is a diagram representing a configuration of a polarization beam splitter 72 according to a second embodiment, [0012] FIG. 5 is a diagram representing a configuration of an image projection apparatus according to a third embodiment.
    Figure 6 is a diagram showing a configuration of an image projection apparatus according to a fourth embodiment.
    DESCRIPTION OF THE EMBODIMENTS
    Embodiments of the present invention will now be described in detail in connection with the accompanying drawings. Each of the embodiments of the present invention described below can be implemented alone or as a combination of a plurality of the embodiments or their features when necessary or when the combination of elements or of features of individual embodiments in a single embodiment is beneficial.
    [First embodiment] (Configuration of image projection apparatus)
    A configuration of a projector; image projection apparatus) P of this embodiment will be described in conjunction with FIG. 1. a projector P comprises a part 11 of light source, an optical illumination system, a polarization beam splitter 12, an image display element (refractive optical modulation part) 7, a polarizing lamina 8, a projection lens (projection optical system) S, and a holding part 9s.
    The light source part 11 comprises a light source 1 such as a very high pressure mercury lamp or an xenon lamp and a reflector 2 which reflects the light coming from the light source 1. The light source part II is capable of emitting light comprising a first beam of colored light, a second beam of colored light and a third beam of colored light which have wavelengths different from each other. More particularly, the light source part 11 is capable of emitting white light containing a red light, a green light and. blue light, The light coming from the light source part il is incident on an array, of micro lens s (or fly eye type lens) 3, where the. light is divided into a plurality of light beams and is condensed. The plurality of light beams thus divided crosses a second array of nterierolenses (or fly eye type lens) 4 and forms a plurality of images of the light source. A polarization conversion element 5 is. disposed near the positions at which the images of the light source are formed. The plurality of light beams, as unpolarized light, incident on the polarization converting element 5 is converted into polarized light having a given polarization direction (which is here assumed to be P polarization) by the element of polarization conversion 5 and is incident on a condensing lens 6. The light coming from the condensing lens 6 passes through the polarization beam splitter 12, which is a polarization separation means (polarization transmission , polarization reflection Si , and is condensed on the image display element 7. It should be noted that in each embodiment of the present invention, the first microlens array, the second microlens array, the polarization converting element and the condensing lens are collectively called the optical illumination system, The light modulated by the image display element 7 is reflected by the polarization beam splitter 12, passes through the polarizing plate S, and is projected, by means of the projection lens 9, onto a screen (projection surface), not shown. The projection lens 9 is held by the holding part 9s. In other words, the holding part 9s is able to hold the projection lens 9. The projection lens 9 can be removable or not removable from the holding part 9s, [0019] (Configuration of beam splitter of . polarization)
    A configuration of the polarization beam splitter (hereinafter called PBS) 12 according to this embodiment will now be described in connection with FIG. 2. The PBS 12 comprises a first prism 21, a substrate 23, a second prism 22, a first adhesive (first adhesive part) 24, a second adhesive (second adhesive part) 25, and a polarizing beam splitting film 26 (polarizing beam splitting part).
    The substrate 23 is linked to a surface 21a of the first prism on the substrate side. 2.3 by the first adhesive 24. The polarizing beam splitting film 26 is deposited in the vapor phase on the surface 22a of the second prism 22 on the substrate side 23 (the second adhesive side 25). The substrate 23 is bonded to the surface 22a, on which the polarizing beam dividing film 26 has been deposited in the vapor phase, by the second adhesive 25. In other words, the first adhesive 24 is in contact with the first prism 21 and the substrate 23, the substrate 23 is in contact with the first adhesive 24 and the second adhesive 25, and the polarizing beam splitting film 26 is in contact with the second adhesive 25 and the second prism 22.
    At the. Figure 2, the. solid line arrow indicates an optical path by which of the. light which is incident on the PBS 12 from the light source part 11 is. subsequently incident on the image display element 7, and the dashed arrow indicates an optical path through which the light from the image display element 7 passes. As shown in FIG. 2, the PBS 12 is able to guide, towards the image display element 7, the light which is incident on the first prism 21 from a first direction and. which passes through the first adhesive 24, the substrate 23, the second adhesive 25, the polarizing beam splitting film 26 and the second, prism 22. At the same time, the PBS 12 is. able to guide the light from the image display element 7 in a second direction which is different from the first direction. To put it differently, the PBS 12 is arranged inside the projector P so as to have this optical action. The first direction mentioned here is a direction indicated by the arrow in line, solid in FIG. 2f or direction of axis z, and the second direction is a direction indicated by arrow in dashed line, or the direction of axis y, With the PBS 12 configured as described above, the image light from the image display element 7 is reflected by the polarizing beam splitting film 26 on the surface 22a of the second prism 22 , and is thus guided towards the projection lens S without passing through the first prism 21 ni. through the substrate 23.
    In the polarization beam splitter described in the Japanese patent application published before examination. ne 2015-45725 mentioned above, the polarizing beam splitting film is sandwiched by two parallel flat blades. For this reason, in the polarization beam splitter described, in the Japanese patent application published before examination No. 2015-45725, when the image light from the image display element is reflected by the film polarizing beam division to be guided towards the projection lens, the image light is incident both on the prism and on the parallel flat plates. Therefore, there is a possibility of influence on the image light by the difference in refractive index between them, increasing 1. ' aberration.
    At. on the contrary, in PBS 12 according to the present embodiment, the image light from the image display element 7 propagates only through the second prism 22 and the beam division film 26 polarizing without passing through the first prism 21 or through the substrate 23, as described above. For this reason, even when materials having different refractive indices are used for the first prism 21 or the second prism 22 and the substrate 23, it is possible to suppress the generation of aberration and to suppress the influence exerted by the beam splitter. of polarization on the image quality, by comparison with the polarization beam splitter described in the Japanese patent application published before examination n ‘2015-45725.
    In addition, the substrate 23 also makes it possible to suppress a temperature increase in the polarizing beam splitting film 26, which occurs because the polarizing beam splitting film 26 absorbs the light incident on PBS 12, More specifically, ri is possible to efficiently disperse, through substrate 23, the heat generated in each adhesive and in the polarizing beam splitting film 26. Therefore, the temperature distribution generated in PBS 12 is reduced, which makes it possible to reduce deterioration in resolution performance due to black flutter and glass deformation which can be attributed to the photoelasticity generated in the second prism 22.
    (Most desirable configuration)
    A more desirable configuration will be described below.
    (Properties of substrate material;
    To better suppress an increase in temperature in the polarizing beam dividing film 26, it is preferable that the substrate 23 has a high thermal conductivity. Specifically, it is preferable that the PBS 12 satisfies the expression A b 4.0 (1) in which A (W / im.K)) denotes the thermal conductivity of the substrate 23.
    It is more preferred that PBS 12 satisfies the expression A> 20.0 (la), In addition, to better suppress a temperature increase in the film. 26 of polarizing beam division, it is preferable that the substrate 23 absorb less heat. Specifically, it is preferable that the PBS 12 satisfies the expression P <0.02 (2), in which P denotes the internal absorbency of the material in a case in which the material used for the substrate 23 has a thickness of 10 mm and in which a light having a wavelength of 460 nm is incident on i. and my mother. a u., [0029] Furthermore, although the glass material of the first prism 21 and of the second prism 22 may be a general-purpose glass used for lenses, and the like, it is preferable that the substrate 23 is made of quartz or. made of sapphire having a low absorbance of visible light and a high thermal conductivity.
    (Properties of prism material)
    In a projector having a high luminance of more than 3000 ha, it is preferable, in addition to using a material having a high thermal conductivity such as quartz or sapphire as the material of the substrate 23, to select the material appropriately of glass of the first prism 21 and of the second, prism 22.
    More particularly, it is preferable that the PBS 12 satisfies at least one of the expressions 0.4 <H1 <2.0 (3), and 0.4 <H2 <2, 0 (4), in which H1 (W / (mK)) denotes the thermal conductivity of the first prism 21 and H2 (W / im, K>) denotes the thermal conductivity of the second prism 22. In particular, it is preferable that the second prism 22 on which is incident the light from the image display element 7 satisfies the expression (4) described above.
    If the thermal conductivity of the prism is less than the lower limit value of expression (4), there is a possibility of insufficient suppression of a temperature increase in the film 26 of polarizing beam division when the luminance light from the light source part 11 is high. On the other hand, many other glass materials having a thermal conductivity greater than the high limit value of expression (4) are too expensive, which does not make them preferable materials.
    It is more preferable that the PBS 12 satisfies at least one of the expressions C, 6 <H1 <1.5 (3a!, And 0.6 <H2 <1.5 (4a).
    It is preferable that the PBS 12 satisfies the expression | N2 - Ni i <0, 1 (5), in which NI denotes the refraction index of the first prism 21 for the line d and N2 denotes the refraction index of the second prism 22 for the line d. It is more preferred that PBS 12 satisfies the expression i N2 - NIi <0.03 (5a).
    If the difference in refractive index between the two prisms is too large to satisfy expression (5), there is a possibility of increasing an aberration such as astigmatism, which is generated by the difference d refractive index between them, reducing the effectiveness of illumination.
    Here, the. photo-elastic constant and internal absorbance of the first prism 21 are respectively designated by Bl · 10 "6 mm2, / N) and QI (where a light having a wavelength of 460 nm is incident on the first prism having a thickness of 10 mm). In addition, the photo-elastic constant and the internal absorbance of the second prism 22 are respectively designated by B2 (10 ~ 6 mm2 / Ni and Q2 (where a light having a wavelength of 460 nm is incident on the second, prism having a thickness of 10 mm). In this case, it is desirable that the PBS 12 satisfies the expressions
    Bl <2.0 (6), B2 <i, 0 (7), Q1 0.03 (8), Q2 <0.02 (9).
    If the PBS 12 does not satisfy expression (6), there is a possibility of a disturbance in the polarization of the first prism 21 due to the photoelasticity which lowers the transmittance of the film 2 6 polarizing beam splitter, thus reducing the lighting efficiency. Note that the upper limit value of the conditional expression (7) can be set to 2.0. In addition, the upper limit value of the conditional expression (9) can be set to 0.03.
    If the PBS 12 does not satisfy the expression (7}, there is a possibility of the appearance of a black floating in the second prism 22 due to the photoelasticity. If the PBS 12 does not satisfy not in expression (8), there is a possibility of the appearance of a temperature distribution in the first prism 21 due to the absorption, and of the appearance of a disturbance in the polarization due to the photoelasticity which lowers the transmittance of the polarizing beam splitting film 26, thereby reducing the illumination efficiency. If the PBS 12 does not satisfy the expression (95, there is a possibility of the appearance of temperature distribution in the second prism 22 due to the absorption, and the appearance of a deterioration in the resolution performance due to a black float and a deformation of glass which can be attributed to the photoelasticity.
    It is more preferable that the PBS 12 satisfies the expressions 31 <1.6 (6a), B2 <0.8 (7a), IQ <0.018 (8a), Q2 <0.01 (9a). Note that the upper limit value of the conditional expression (7a) can be set to 1.6. In addition, the upper limit value of the conditional expression (9a) can be set to 0.018.
    In addition, as described above, since the image light from the image display element 7 is guided towards the projection lens 9 through the second prism 22, it is preferable that the second prism 22 has a lower photoelasticity constant and also an internal absorbance lower than that of the first prism 21. In other words, it is preferable that the PBS 12 satisfies at least one of the expressions
    Bl> B2 (10), and IQ> Q2 (11) - [0040] (Methods of implementation in figures)
    In the following, numerical embodiments of the polarization beam splitter are shown.
    (Embodiment 1 in figures)
    First prism: 3F6.HT (SCHOTT} H1 - 0.673, NI = 1.805, 31 = 0.65, Qi = 0.003
    Second prism: SF6HÏ (SCHOTT) H2 = 0.673, N2 - 1.805, B2 - 0.65, Q2 - 0.008
    Substrate: sapphire A - 25 (Embodiment 2 in figures)
    First prism; S-FPM2 (OHARA) H1 = 0.624, NI = 1.595, Bl - 0.51, Qi === 0.008
    Second prism: S-FPM2 (OHARA) H2 - 0.624, N2 - 1.595, B2 = 0.51, Q2 = 0.008
    Substrate: sapphire A = 25 {Embodiment 3 in figures)
    First prism: S-FPM2 (OEARA) H.1 - 0.624, Ni - 1.535, Bl - 0.51, IQ = 0.008
    Second prism: LBC3N (HOYA) H2 = 0.443, N2 = 1.606, B2 - 0.43, Q2 - 0.003
    Substrate: sapphire A - 25 (Embodiment 4 in figures)
    First prism: S-LAH8 9 (OHARA) H1 - 0.861, NI - 1.852, Bl = 1.27, IQ = 0.017
    Second prism: PBH56 (OHARA) H2 = 0.635, N2 - 1.84d., B2 === 0.03, Q2 - 0.005
    Substrate: sapphire A - 25 (Embodiment 5 in figures)
    First prism: S-LAHS7 (OHARA)
    El = 0.863, NI = 1.755, Bl - 1.33, IQ - 0.003
    Second prism: S-LAH97 (OHARA) H2 - 0.863, N2 === 1.755, B2 - 1.39, Q2 = 0.003
    Substrate: sapphire A = 25 Note that the result of calculation of expression (5) of each embodiment in figures is as mentioned in table 1 below.
    Table 1_
    Mode of 1 2 3 4 5 realization in figures N2 1.805 1.595 1.606 1.841 1.755 NI 1.805 1.595 1.595 1.352 1.755 j N2 - Nl | __________.______________ 0 .................... .......... 0 0.011 0, 011_0 [0044] (Slow axis direction of the substrate)
    Figures 3A and 3B show the direction of the slow axis of the substrate 23, In Figures 2, 3A. and 3B, the z axis direction is a direction parallel to the normal direction of the image display element 7, and the y axis direction is a direction orthogonal to the z axis direction and in which light propagates from PBS 12. The x-axis direction is a direction orthogonal to the z-axis direction and the y-axis direction. The direction of axis b is a direction parallel to the normal direction of the substrate 23, and the direction of axis a is a direction orthogonal to the direction of axis x and to the direction of axis b and is parallel to the plane d incidence of the substrate 23 and to the direction of the short side of the substrate 23.
    It is preferable that the direction of the slow axis of the birefringence substrate 23 is substantially parallel to the direction of axis x or to the direction of axis a, as illustrated in Figures 3.Ά and 3B. The expression "substantially parallel" means that the angle of the slow axis relative to the x axis or to the a axis is 0 ’± 5 °. If this range of values which corresponds to the expression "substantially parallel" is not satisfied, too great a phase difference is given to the polarized light (whose direction of polarization is parallel to the x axis or to the y axis which is incident on PBS 12, which leads to an increase in loss of illuminating light at BBS 12.
    The direction of the slow axis of the substrate 23 can be expressed as follows using the direction of polarization of the light incident on the PBS 12. Specifically, the angle formed by the slow axis of the substrate 23 by with respect to the direction of polarization of the incident light, incident on the film 26 of polarizing beam division, falls within a range of 0 ° ± 5 ° or 90 ° ± 5 °.
    In addition, it is preferable that the PBS 12 satisfies the expression [Ne - Ko)> 0.004 (12), in which Ne denotes the refractive index of the substrate 23 for the ordinary ray line radius d and No denotes the refractive index of the substrate 23 for the extraordinary ray radius d.
    As described. above, in this embodiment, the light modulated by the image display element 7 and guided towards the screen, that is to say the image light, is guided by the element 7 for image display passing through the second prism 22 and through the polarizing beam splitting film 26, and thus from the PBS 12 towards the screen, or in the direction of the projection lens 9 (the second direction] In this way, the image light is emitted from the PBS 12 without passing through the substrate 23 or the adhesive parts. For this reason, even if the first adhesive part 24 or the second adhesive part 25 is deteriorated, the light d the image will not be affected by the deterioration.
    In addition, the configuration in which the image light is guided from the PBS 12 to the screen or in the direction of the projection lens 9 (the second direction) via the second prism 22 and the film 26 polarizing beam splitting is common between the PBS described in this embodiment and a normal PBS. The normal PBS mentioned here refers to a PBS in which a polarizing beam splitting film is sandwiched by two prisms without comprising a substrate. In the PBS described in the Japanese patent application published before examination No. 2015-45725 mentioned above, it is necessary to design the polarizing beam splitting film by taking into account the refractive indices of both the substrate and the prism on the element side, image display rather than polarizing beam splitting film. However, the polarizing beam dividing film mounted in the PBS described in this embodiment may be of the type which takes into account the refractive index of the prism on the image display element side, such as a polarizing beam splitting film for mounting in a normal PBS. In other words, the PBS described in this embodiment can use a polarizing beam splitting film mounted in normal PBS.
    In addition, since the present embodiment does not employ the configuration according to which a polarizing beam splitting film is sandwiched between two substrates, it is possible to obtain a PBS of simpler configuration than that of the PBS described in the Japanese patent application published before examination No. 2015-45725 mentioned above, [Second embodiment]
    A configuration of a PBS 72, which is a polarization beam splitter of a second embodiment, will be described in connection with FIG. 4.
    The difference in configuration of PBS 72 of this embodiment compared to PBS 12 of the first embodiment described. above is a substrate. In PBS 72, a substrate 83 has a size such that substrate 83 projects from the first prism 21 and the second prism 22. In other words, PBS 72 has a configuration which satisfies the expression 1.0 <D2 / D1 <1.5 (13), in which DI denotes the length of the surface 21a of the first prism 21 in the direction of a diagonal of the PBS 72 and D2 denotes the length of the substrate 83. If the substrate 83 is too long to satisfy the high limit value of expression (13), this is not preferable since the substrate 83 may possibly interfere with another organ. In addition, if the distance between the substrate. 83 and a neighboring organ is increased to avoid this interference, this is not preferable from the wax that the projector P will have a larger size.
    This configuration makes it easier to dissipate heat from the beam splitting film 26 polarizing towards the outside of the PBS 72 by means of the substrate 83 by comparison with the first embodiment described above. Therefore, it is possible to better suppress an increase in temperature of the polarizing beam splitting film 26. In addition, it is desirable that the substrate 83 protrude from the PBS 72 by 5 mm or more. Note that the substrate 83 is made of a material having a high thermal conductivity, such as sapphire, as in the case of the first embodiment described above. In the present embodiment, DI ~ 28 mm, D2 - DI + 5 mm = 33 mm and D2 / D1 = 1.18 ('but it is possible to use any value of DI and D2 satisfying the requirements of 1 / expression (13)), it is possible to cool the temperature of the polarization beam splitter 72, and thus further improve the optical performance, by blowing cooling air against the substrate 83 which protrudes from the polarization beam splitter 72. That is to say that it is preferable for the projector P to comprise a cooling part 84 intended to cool at least a part of the substrate 83 which projects out of the PBS 72. The arrow in solid line in FIG. 4 indicates the path of circulation of the cooling air from the cooling part 84. The cooling part 84 is a cooling fan such as a sirocco fan. or an axial fan.
    [Third embodiment]
    A configuration of a PI projector according to a third embodiment will be described in connection with FIG. 5. Since the configurations of the light source part 11, of the optical illumination system, of the projection lens 3 and of the holding part. 3s are the same as those of the first embodiment described above, their description will not be given. However, in the present embodiment, a first condensing lens 39 and a second condensing lens 43 perform the same functions as those of the condensing lens 6.
    In Figure 5, the pins 40, 45 and. 47 denote first, second and third polarization beam splitters all having the same structure as that of. PBS 12 from the first embodiment described above. The references 41, 46 and 48 denote first, second and third parts of refractive optical modulation and, more specifically, first, second and third parts of refractive liquid crystal panels. Each of the references 41, 46 and 48 may also relate respectively to. first, second and third image display elements.
    Light from the optical illumination system is incident on a dichroic cross mirror 52. The dichroic cross mirror 52 includes a first dichroic mirror 36 having light reflection properties in the god band and transmission light in the green band and light in the red band and a second dichroic mirror 37 having properties of light transmission in the blue band and light reflection in the green band and light in the band of red. The light whose polarization has been converted to P polarization in a polarization converting element 35 is reflected by the cross dichroic mirror 52 so that the light in the blue band is reflected towards a first mirror 38 and that the light in the green band and the light in the red band are reflected towards a second mirror 42.
    Note that the light in the blue band, or blue light, mentioned here is such that the wavelength or. total width at half height (LTMH) of the light having the maximum intensity in the spectral distribution of the light is contained in the band from 430 to 480 nm.,
    The light in the green band, or green light, is such that the wavelength or full width at half height (LTMH) of the light having the maximum intensity in the spectral distribution of the light is contained in the band from 500 to 580 nm. The light in the red band, or red light, is such that the wavelength or total width at mid-height (ILTMH) of the light having the maximum intensity in the. spectral distribution of light is contained in the band from 600 to 750 nm.
    Polarized light in the blue band which has been emitted from the dichroic cross mirror 52 and reflected by the first mirror 38 passes through the first condensing lens 39 and the first PBS 40 and illuminates the first image display element 41. The image light (polarized light S) which has been modulated by the first image display element 41 is reflected by the first PBS 40, and is then reflected by a dichroic cross prism 49, and is guided towards ia projection lens 9.
    The polarized light P in the bands of green and red which has been emitted from the dichroic cross mirror 52 and reflected by the second mirror 42 passes through the second condensing lens 43 and is incident on a third dichroic mirror 44. The light in the band of green is reflected by the third dichroic mirror 44 March the light in the band of red passes through the third dichroic mirror 44.
    The polarized light P in the green band which has been reflected by the third dichroic mirror passes through the second PBS 45 and illuminates the second image display element 46. The image light (polarized light S) which has been modulated by the second image display element 46 is. reflected by the second PBS 45, crosses the cross dichroic prism 49 and is guided towards the projection lens 9.
    The polarized light P in the red band that is. passed through the third dichroic mirror 44 then passes through the third PBS 47 and illuminates the third image display element 48. The image light (S-polarized light) which has been modulated by the third image display element 48 is reflected by the third PBS 47, then is reflected by the cross dichroic prism 49, and is guided towards the lens projection light 9, The image light which has been transferred to the projection lens 9 is projected onto a screen, not shown.
    Note that, although not shown in FIG. 5, it is desirable to have a polarization plate of the absorption type which absorbs light from a direction of polarization. · Useless in an optical path between the first, second and third PBS and the cross dichroic prism 49.
    In the present embodiment, all the PBS of the respective light colors, which all have the same configuration as that of the PBS 12, are organized so that the image display elements of the respective light colors are positioned in the directions in which the incident light beams pass through the respective PBS. For this reason, as in the case of the first embodiment described above, it is possible, in the present embodiment, to also remove the influence of the polarization beam splitters on the image quality while suppressing an increase in temperature in the polarizing beam splitting portions, as compared to the conventional technique.
    Ά note that, in the present embodiment, the dichroic cross mirror 52 is. the color discrimination part, and that the cross dichroic prism 49 is the color combination part.
    [Fourth embodiment]
    A configuration of a projector P2 according to a fourth embodiment will be described in connection with FIG. 6. Since the configurations of the. part 11 of the light source and of the optical illumination system are the same as those of the first embodiment described above, their description will not be given.
    Light from an optical illumination system is incident on a dichroic mirror 91. The dichroic mirror 91 has properties of light transmission in the band of green and reflection of light in the band of red and of light in the blue band.
    The light in the green band which has passed through the dichroic mirror 91 then passes through a second PBS 45 and is incident on a second image display element 46. The polarized light S in the green band which has. been modulated by the second image display element 46 is reflected by the second PBS 45, then is reflected by a synthetic prism 95, and is guided towards a projection lens 9. The synthetic prism 95 has properties of light reflection in the green band regardless of the direction of polarization, of light transmission in the blue band regardless of the direction of polarization, and of polarization de-division of light in the red band.
    The light in the red band and the light in the blue band, which were reflected by the dichroic mirror 91, pass through a wavelength selection wave plate 92 so that only the light in the blue stripe is converted from polarized light P to polarized light S, and are then incident on a fourth PBS 93. The fourth PB3 93 has functions for guiding polarized light S in the blue stripe to the first element 41 of image display while guiding the polarized light P in the red band to the third image display element 48.
    The polarized light P in the blue band which has been modulated by the first image display element 41 passes through the fourth PBS 93 and is converted into polarized light S in the blue band by a λ / 2 blade 94 , which then passes through the synthesis prism 95 and which is guided towards the projection lens 9. Among the light in the red band which passed through the fourth PBS 93 and which was then incident on the third element 48 display of image, the polarized light S in the red band which has been modulated by the third image display element 48 is converted into a polarized light P in the red band by the blade λ / 2 94, and is then guided towards the projection lens 9 passing through the synthesis prism 95. Note that the fourth PBS 93 has the same configuration as that of PBS 12 of the first embodiment described above.
    In the fourth PBS 93, the light in the red band coming from the third image display element 48 is guided towards the projection lens 9 without passing through the substrate 23. On the other hand, the light in the blue stripe coming from the first image display element 41 is guided towards the projection lens 9 through two prisms and through the substrate 23. In a case in which. two image display elements are provided for a single PBS, the effects described with respect to the first embodiment described above cannot therefore be obtained for light of a single color. Therefore, in the present embodiment, the third red light image display member 48, which has higher relative visibility, is arranged in the direction in which the light passes through the fourth PBS 93. In this way, it is possible to reduce the influence of an aberration, which receives the red light having a higher relative visibility.
    [Modifications]
    Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and variations may be made within the scope of the present invention.
    For example, although the configurations according to which the light source part is a lamp, have been described in the embodiments mentioned above, the present invention is not limited to this type of configuration. As soon as the light source part is capable of emitting white light, the light source part can for example be configured by means of a laser diode {DLS or of an LED which emits red light, a DL or an LED which emits green light, and a DL or an LED which emits blue light. In addition, the light source portion can be configured to emit a Board light by means of a yellow phosphor and a DE: or an LED which emits blue light.
    In addition, although the configurations in which the polarization beam splitting part is a polarizing beam dividing film or, more specifically, a multilayer dielectric film, have been illustrated in the embodiments described above , the present invention is not limited to this type of configuration. Since the polarizing beam splitting part separates the incident light based on the polarization direction of the light, the polarizing beam splitting part can, for example, be a structured polarizing beam splitting part , or the like, in place of the film, a multilayer dielectric.
    In addition, although the configuration in which the substrate 83 projects from the PBS 72 in the direction of a diagonal of the PBS 72 in the. section y-z, has been illustrated in the second embodiment described above, the present invention is not limited to this type of configuration. Ti is possible to employ a configuration in which the substrate 83 projects in the x-axis direction or a configuration in which the substrate 83 also projects in the x-z section and in the x-axis direction, and the like. It is also possible to use a configuration in which the substrate 83 projects on each side of the PBS 72.
    In addition, although the configurations using the first adhesive part and the. second adhesive part have been illustrated in the embodiments described above, the present invention is not limited to this type of configuratron, for example, it is possible to use a configuration in which the arrangement of the first prism, the substrate, the polarizing beam dividing portion and the second prism is fixed with a structure which biases one of the first prism and the second prism against the other.
    In addition, the first, second and. third embodiments described above employ the configuration in which the image display member is positioned in the direction in which the light incident on the PBS passes through the polarizing beam splitting portion. However, the present invention is not limited to this type of configuration. For example, in the first, second and. third embodiments described above, it is possible to employ a configuration in which the image display member is positioned in a direction in which the light incident on the PBS is. reflected by the polarization beam splitting part. In this case, the direction of polarization to be regulated in the polarization converting element can be changed to a polarization direction different from 90 J from that of the first, second and third embodiments described above.
    In addition, in the fourth embodiment described above, it is possible to use a configuration in which the second image display element 46 is positioned in a direction in which a green light incident on the second PBS 45 is reflected by the polarizing beam splitting portion.
    Although the present invention has been described in connection with embodiments given by way of example, it should be understood that the invention is not limited to the embodiments given by way of example described.
    权利要求:
    Claims (15)
    [1]
    1. polarization beam splitter ¢ 12), comprising: a first prism (21); a second prism (22); a polarization beam splitting portion (26) in contact with the second prism; a substrate (23) disposed between the polarization beam splitting portion and the first prism; a first adhesive portion (24) disposed between the first prism and the substrate; and a second adhesive part (25) disposed between the polarization beam division part and the substrate,
    [2]
    The polarization beam splitter according to claim 1, wherein the polarization beam splitter (12) is adapted to guide light which is incident on the first prism from a first direction through the first polarization beam splitter. to a refractive optical modulation part, so that the light passes through the first prism, the first adhesive part, the substrate, the second adhesive part, the polarization beam splitting part and the second prism, in this order, and in which the polarization beam splitter (12) is capable of guiding light which has been modulated by the refractive optical modulation part from the first direction to a different second direction,
    [3]
    3. A polarization beam splitter according to claim 1 or 2, in which a conditional expression A> 4, 0 is satisfied, in which A denotes a thermal conductivity (W / (m, K)) of the substrate.
    [4]
    4. A polarization beam splitter according to any of claims 1 to 3, wherein the polarization beam splitting portion is a polarizing beam splitting film which has been vapor deposited on a surface of the second prism on the substrate side.
    [5]
    5. A polarization beam splitter according to claim 1, in which at least one of the expression 0.4 <H1 <2.0 and of the expression 0.4 <H2 <2 , 0 is satisfied, in which Hi and H2 respectively denote thermal conductivities (H / im.Ki; of the first prism and of the second prism, o, polarization beam splitter according to any one of claims 1 to 5, in which the express! o ns co nd it ion n they Bl <2,0, B2 <2,0, Q1 1 0,03, and Q2 <0,03 are satisfied, in which B! denotes a photo-elastic constant (10 -6 mm2 / N) of the first prism, Q1 denotes an internal absorbance in a case in which a light having a wavelength of 460 nm is incident on the first prism having a thickness of 10 mm, B2 denotes a photo constant elastic (10-6 mm2 / K) of the second prism, and Q2 designates an internal absorbance in a case where a light having a wavelength of 460 nm is incident on the second prism having a thickness of 10 mm,
    [7]
    7, A polarization beam splitter according to any one of claims 1 to 5, wherein the conditional expressions 31 <2.0, B2 <1.0, Q1 <0.03, and Q2 <0.02 are sat. isfa.ites, in which Bl denotes a photo-elastic constant (1.0'6 W / N; from the first prism, Qi denotes an internal absorbance in a case in which light having a wavelength of 460 nm is incident on the first prism having a thickness of 10 mm, 32 denotes a photo-elastic constant (10 ~ 6 mm2 / N} of the second prism, and Q2 denotes an internal absorbance in a case in which a light having a wavelength of 460 nm is incident on the second prism having a thickness of 10 nm.
    [8]
    8. polarization beam splitter according to any one of claims 1 to 7, in which a conditional expression 31> B 2 is satisfied, in which Bl denotes a photo-elastic constant (10 ~ 6 mm2 / N) of the first prism and B2 denotes a photo-elastic constant (1Q ~ S mm2 / N) of the second prism,
    [9]
    9. Polarization beam splitter according to any one of claims 1 to 8, in which a conditional expression Q1> Q2 is satisfied, in which Qi denotes an internal absorbance in a case in which · a light having a wavelength of 460 nm is incident on the first prism having, a thickness of 10 mm and Q2 denotes an internal absorbance in a case in which a light having a wavelength of 4 60 nm is incident on the second prism having a thickness of 10 mm.
    [10]
    10. Polarization beam splitter according to any one of claims 1 to 3, in which the substrate is birefringent, and a conditional expression te - No | > 0.004 is satisfied, in which Ne designates a refractive index of the substrate for an ordinary radius of line d and No designates a refractive index of the substrate for an extraordinary radius of line d.
    [11]
    11. A polarization beam splitter according to any one of claims 1 to 10, wherein an angle formed by a slow axis of the substrate, with respect to a direction of polarization of incident light incident on the beam splitter portion of polarization, falls within a range of 0 ° ± 5 'or 90 ° ± 5 °.
    [12]
    12. An image projection apparatus (P), comprising; a light source part (11) capable of emitting light containing, a first beam of colored light, a second beam of colored light and. a third beam of colored light which have wavelengths different from each other; the polarization beam splitter according to any of claims 1 to 11; a refractive optical modulation part (7); ef, a holding part (9s) adapted to hold a projection optical system which guides a light from the refractive optical modulation part to a projection surface, in which the polarization beam splitter is arranged so that a light from a light source portion passes through the polarization beam splitter and is incident on the refractive optical modulation portion, and light modulated by the refractive optical modulation portion is reflected by the polarization beam splitter .
    [13]
    The image projection apparatus according to claim 12, further comprising: a first refractive optical modulation portion which modulates the first beam of colored light, a second refractive optical modulation portion which modulates the second beam of colored light and a third refractive optical modulation part which modulates the third beam of colored light, as refractive optical modulation part; a color discriminating part which guides a beam of colored light among, the first beam of colored light, the second beam of colored and. the third beam of colored light in a direction different from that of the other two beams of colored light; and a color combination part which combines a light beam from the first refractive optical modulation part, a light beam from the second refractive optical modulation part and a light beam from the third refractive optical modulation part .
    [14]
    14, Image projection apparatus. according to claim 13, further comprising: a first polarization beam splitter which guides the first beam of colored light towards the first refractive optical modulation part, a second polarization beam splitter which guides the second beam of colored light towards the second refractive optical modulation portion, and a third polarization beam splitter which guides the third beam of colored light to the third refractive optical modulation portion, as a polarization beam splitter, wherein the first polarization beam splitter is arranged so that the first beam of colored light passes through the first polarization beam splitter and is incident on the first refractive optical modulation part, the second polarization beam splitter is. arranged so that the second beam of colored light passes through the second polarization beam splitter and is incident on the second refractive optical modulation part, and the third polarization beam splitter is arranged so that the third beam of colored light passes through the third polarization beam splitter and is incident on the third part of refractive optical modulation.
    [15]
    The image projection apparatus according to claim 13, further comprising: a second polarization beam splitter which guides the second beam of colored light to the second refractive optical modulation part and. a fourth polarization beam splitter which guides the first beam of colored light to the first refractive optical modulation part and which guides the third beam of colored light to the third refractive optical modulation part, as a polarization beam splitter.
    [16]
    16. An image projection apparatus according to claim 15, wherein the second polarization beam splitter is arranged such that the second beam of colored light passes through the second polarization beam splitter and is incident on the second part of refractive optical modulation, the fourth polarization beam splitter is arranged so that the third beam of colored light passes through the third polarization beam splitter and is incident on the third part of refractive optical modulation, and relative visibility of the third beam of colored light is greater than a relative visibility of the first beam of colored light.
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    同族专利:
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    DE102018007521A1|2019-04-04|
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    法律状态:
    2019-08-23| PLFP| Fee payment|Year of fee payment: 2 |
    2021-01-01| PLSC| Search report ready|Effective date: 20210101 |
    2021-06-11| ST| Notification of lapse|Effective date: 20210506 |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2017191758|2017-09-29|
    JP2017191758|2017-09-29|
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