Projection display device

Abstract

To provide a projection lens unit and a projection type display device that can improve color uniformity of an image to be projected.SOLUTION: Provided are a projection lens unit that enlarges and projects, on a projection object, image light output from an image forming unit and including first light and second light in a longer wavelength band than that of the first light, and a projection type display device including the same. The projection lens unit includes a plurality of lenses coated with a first anti-reflection film, and a wavelength selection filter having a first area at the center through which an optical axis passes and a second area around the first area. In the wavelength selection filter, the transmittance of the first light is lower than that of the second light, and the situation is more obvious in the second area than in the first area.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a projection lens unit and a projection display device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is a projection display device that includes a projection lens unit that enlarges and projects image light emitted from an image forming unit onto a projection target such as a screen.

[0003] For example, the projection display device in Patent Document 1 employs a wide-angle lens group as a projection lens unit, and describes that an image provided by a DMD is projected onto a screen by a relay lens group and a wide-angle lens group. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2007-525700 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a projection lens unit is used, color uniformity may be lost from the center to the periphery of the projected image on the projection target, especially when a wide-angle projection lens unit is used.

[0006] Therefore, an object of the present disclosure is to solve the above-mentioned problems and to provide a projection lens unit and a projection display device that can improve the color uniformity of a projected image. [Means for solving the problem]

[0007] To achieve the above object, the projection lens unit of the present disclosure is a projection lens unit that enlarges and projects image light, which is output from an image forming unit and includes first light and second light having a wavelength band longer than that of the first light, onto a projection target. The projection lens unit includes a plurality of lenses coated with a first anti-reflection film, and a wavelength-selective filter having a first central region through which an optical axis passes and a second region surrounding the first region. In the wavelength-selective filter, the transmittance of the first light in the second region is lower than the transmittance of the first light in the first region.

[0008] Another aspect of the present disclosure provides a projection lens unit that enlarges and projects image light, which is output from an image forming unit and includes a first light and a second light having a wavelength band longer than that of the first light, onto a projection target. The projection lens unit includes a plurality of lenses coated with a first anti-reflection film, and a wavelength-selective filter having a first central region through which an optical axis passes and a second region surrounding the first region, and the transmittance of the second light in the first region is lower than the transmittance of the second light in the second region.

[0009] A projection display device according to the present disclosure includes any one of the projection lens units described above, a light source unit that emits light, and an image forming unit that uses the light from the light source unit to output image light. [Effects of the Invention]

[0010] It is possible to provide a projection lens unit and a projection display device that can improve the color uniformity of a projected image. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 10 is a partial enlarged view of a projection lens unit according to a comparative example. [Figure 2] Graph showing the spectral transmittance for each optical path of the entire projection lens unit according to the comparative example. [Figure 3] 10 is a graph showing the difference in transmittance between light on the optical axis of a projection lens unit according to a comparative example and light in the optical path at the maximum angle of view. [Figure 4] FIG. 1 shows a configuration of a projection display device according to a first embodiment. [Figure 5] FIG. 1 is a diagram showing a configuration of a wavelength selection filter according to a first embodiment; [Figure 6] Graph showing the spectral reflectance of the first and second antireflection films according to the first embodiment. [Figure 7] Graph showing the spectral reflectance of the first wavelength selective film according to the first embodiment [Figure 8] FIG. 10 is a diagram showing a configuration of a projection display device according to a modification of the first embodiment. [Figure 9] FIG. 10 is a diagram showing a configuration of a wavelength selection filter according to a modification of the first embodiment; [Figure 10] FIG. 10 is a diagram showing the configuration of a wavelength selection filter according to a second embodiment. [Figure 11] Graph showing the spectral reflectance of the second wavelength selective film according to the second embodiment [Figure 12] FIG. 10 is a diagram showing the configuration of a wavelength selection filter according to a third embodiment. [Figure 13] 10 is a graph showing the spectral reflectance of a first wavelength selective film according to the third embodiment. [Figure 14] Graph showing the spectral reflectance of the second wavelength selective film according to the third embodiment [Figure 15] FIG. 10 is a diagram showing the configuration of a projection display device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0013] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0014] First, referring to FIG. 1, the problems with the projection lens unit of the present disclosure will be described in more detail. The inventors have newly discovered the cause of the loss of color uniformity due to the projection lens unit. Specifically, the projection lens unit has multiple lenses, and the angle of incidence of image light on each lens surface tends to change depending on the angle of view. An anti-reflection coating is formed on the surface of each lens, and the incidence angle dependency of the anti-reflection coating causes a loss of color uniformity from the center to the periphery of the image on the projection target.

[0015] FIG. 1 is a partially enlarged view showing the configuration of a portion of a projection lens unit 81 in a comparative example. The projection lens unit 81 includes a plurality of lenses for magnifying image light and reducing aberration of the image light. The projection lens unit 81 includes, for example, approximately 10 to 30 lenses. FIG. 1 shows lenses Ln11 to Ln20 on the screen side of the plurality of lenses. An anti-reflection film is formed on the light entrance surface and light exit surface of each of the lenses Ln11 to Ln20.

[0016] In the case of the optical path Lf1 on the optical axis of the projection lens unit 81, the angle of incidence of light on each of the lenses Ln11 to Ln20 is close to 0 degrees. In contrast, in the case of the optical path Lf2, which has the maximum angle of view of the projection lens unit 81, the angle of incidence of light on each of the lenses Ln11 to Ln20 becomes larger. For example, the angles of incidence of light on the lenses Ln13 and Ln19 are very large, and in this way the angles of incidence of light become very large at multiple points on each of the lenses Ln11 to Ln20.

[0017] The anti-reflection coating formed on each lens Ln11 to Ln20 has the property that the wavelength band that suppresses reflectance shifts to the shorter wavelength side when the angle of incidence of light is large. When the angle of incidence of light is large, for example, the reflectance of light in the red wavelength band increases and the reflectance of light in the blue wavelength band decreases. Therefore, when red light propagates along an optical path with a wide angle of view, the amount of reflected light is greater than that of an optical path on the optical axis, and the peripheral areas of the projected image appear bluish compared to the central area.

[0018] FIG. 2 is a graph showing the spectral transmittance for each optical path of the entire projection lens unit according to the comparative example. Therefore, FIG. 2 shows the integrated value of the transmittance of all lenses in the projection lens unit. The spectral transmittance of light on the optical axis is approximately 90% for light with wavelengths between 450 nm and 650 nm, so the chromaticity of the projected image on the optical axis is uniform. In contrast, the spectral transmittance of light on the optical path Lf2 at the maximum angle of view is approximately 65% for light with wavelengths between 450 nm and 600 nm, while the transmittance of light with wavelengths of 600 nm or more gradually decreases. Therefore, the uniformity of the chromaticity of the projected image decreases near the maximum angle of view.

[0019] 3 is a graph showing the difference in transmittance between light along optical path Lf1 on the optical axis and light along optical path Lf2 at the maximum angle of view in a projection lens unit 81 according to a comparative example. As the wavelength of light passing through the projection lens unit 81 becomes longer, the difference in transmittance between optical path Lf1 on the optical axis and optical path Lf2 at the maximum angle of view tends to increase, which causes color variations in the image projected onto the screen. The projection lens unit and projection display device of the present disclosure have a configuration that solves this problem.

[0020] (Embodiment 1) [1-1. Configuration of the projection lens unit and projection display device] The following describes a projection lens unit and a projection display device according to embodiment 1 of the present disclosure. Fig. 4 is a diagram showing the configuration of the projection display device 1 according to embodiment 1 of the present disclosure. Fig. 5 is a diagram showing the configuration of the wavelength selection filter 13 of the projection display device 1 according to embodiment 1, with Fig. 5(a) being a cross-sectional view of the wavelength selection filter 13 and Fig. 5(b) being a front view of the wavelength selection filter 13.

[0021] As shown in FIG. 4, a projection display device 1 according to an embodiment of the present disclosure includes a light source unit 3 that irradiates light, an illumination optical system 5, an image forming unit 7 that outputs image light using the light from the light source unit 3, and a projection lens unit 9.

[0022] The light source unit 3 includes a light source element and a focusing optical system that focuses the light output from the light source element. The light source element typically uses a discharge lamp, a solid-state laser, an LED, etc. The light source unit 3 may emit light of different wavelengths in a time-division manner, or may constantly emit white light.

[0023] The illumination optical system 5 includes an integrator element 5a that homogenizes the illuminance distribution of the output light from the light source unit 3, and a relay lens 5b consisting of multiple lenses that efficiently illuminates the light emitted from the integrator element 5a onto the image forming unit 7. In Fig. 4, a rod prism is shown as an example of the integrator element 5a, but a system using a lens array may also be adopted.

[0024] The image forming unit 7 is a light valve that functions as a light modulation unit and modulates incident light in the visible light range to form image light. The image forming unit 7 may include, for example, a transmissive or reflective liquid crystal display element that forms an image by controlling the polarization component of light, or a reflective digital micromirror device (DMD) element that forms an image by controlling the traveling direction of light using a micromirror.

[0025] The image forming unit 7 outputs the light incident from the light source unit 3 and the illumination optical system 5 as image light of, for example, three wavelength bands, first to third. The image light is light in the visible light band, and the first light is, for example, light in the blue wavelength band, having a wavelength band of 430 nm or more and 500 nm or less. The second light is, for example, light in the red wavelength band, having a wavelength band of 600 nm or more and 670 nm or less. The third light is, for example, light in the green wavelength band, having a wavelength band of more than 500 nm and less than 600 nm.

[0026] The projection lens unit 9 includes multiple lenses Ln1 to Ln5 and a wavelength-selective filter 13. The projection lens unit 9 enlarges and projects the output light from the image forming unit 7 onto the screen 15. While FIG. 4 shows five lenses Ln1 to Ln5 in the projection lens unit 9, this is merely a simplified illustration. Therefore, the projection lens unit 9 may include, for example, approximately 10 to 30 lenses, such as lenses Ln11 to Ln20 as shown in FIG. 1. With these multiple lenses, the maximum angle of view of the projection lens unit 9 is 60 degrees or greater. Furthermore, the entrance and exit surfaces of each of the lenses Ln1 to Ln5 in the projection lens unit 9 are each coated with a first anti-reflection film 10. This prevents light incident on each of the lenses Ln1 to Ln5 from reflecting off the lenses Ln1 to Ln5 and becoming stray light. The anti-reflection film 10 is, for example, a film formed by laminating dielectric films.

[0027] In FIG. 4, the wavelength-selective filter 13 is disposed on the image forming unit 7 side of the projection lens unit 9, but it may also be disposed on the screen 15 side. In FIG. 4, the wavelength-selective filter 13 is disposed closer to the image forming unit 7 than the lens Ln1 disposed closest to the image forming unit 7, but it may also be disposed near the lens Ln1 disposed closest to the image forming unit 7. For example, the wavelength-selective filter 13 may be disposed between the lenses Ln1 and Ln2. In this way, "disposed on the image forming unit 7 side" includes not only the end of the projection lens unit 9 on the image forming unit 7 side but also the vicinity of the end. Similarly, "disposed on the screen 15 side" includes not only the end of the projection lens unit 9 on the screen 15 side but also the vicinity of the end. For example, the wavelength-selective filter 13 may be disposed closer to the screen 15 than the lens Ln5 disposed closest to the screen 15, or it may be disposed between the lenses Ln4 and Ln5.

[0028] The wavelength-selective filter 13 is disposed, for example, at a position sufficiently far from the image plane of the image forming unit 7, i.e., at a position sufficiently defocused, and with the light rays at each angle of view as far apart as possible. In this arrangement, the difference in the angle of incidence between the optical axis 11 and the maximum angle of view can be reduced. When disposed closest to the image forming unit 7, the size of the wavelength-selective filter 13 can be reduced, and the dependency of the wavelength-selective filter 13 on the angle of incidence can also be reduced. Furthermore, a continuous filtering effect can be applied to the image light passing through the wavelength-selective filter 13 according to the angle of view. The wavelength-selective filter 13 may be disposed on the screen 15 side of the projection lens unit 9, but in this case, the size of the wavelength-selective filter 13 will be larger.

[0029] [1-2. Wavelength selection filter configuration] The configuration of the wavelength-selective filter 13 will be described with reference to FIG. 5. The wavelength-selective filter 13 has different light transmittances depending on the wavelength band between a central first region Ar1 through which the optical axis 11 passes and a surrounding second region Ar2. The spectral transmittance of the wavelength-selective filter 13 changes rotationally symmetrically about the optical axis 11 of the projection lens unit 9. Note that "changing rotationally symmetrically about the optical axis 11" includes changing rotationally symmetrically not only about the optical axis 11 but also about the vicinity of the optical axis 11. In the first embodiment, the transmittance of the first light in the annular second region Ar2 is lower than the transmittance of the first light in the circular first region Ar1. The transmittance of the second light in the first region Ar1 and the second region Ar2 is substantially the same.

[0030] The wavelength-selective filter 13 includes a transparent substrate 13a, a second anti-reflection film 13b formed on the light-incident and light-exiting surfaces of the transparent substrate 13a, and a first wavelength-selective film 13c1.

[0031] The transparent substrate 13a transmits image light from the image forming unit 7. The transparent substrate 13a is, for example, a resin plate or a glass plate.

[0032] The second antireflection film 13b reduces reflection of image light incident on the transparent substrate 13a. The second antireflection film 13b has a circular shape and is formed at least in the light transmitting areas of the incident surface and the exit surface of the transparent substrate 13a.

[0033] Fig. 6 is a graph showing the spectral reflectance of the first and second antireflection films 10 and 13b according to embodiment 1. As shown in Fig. 6, the spectral reflectance of the first and second antireflection films 10 and 13b is 1% or less over the entire visible light wavelength band of approximately 430 nm to 670 nm.

[0034] In the first embodiment, the first wavelength selective film 13c1 has a lower transmittance for the first light than for the second light. The first wavelength selective film 13c1 is, for example, a dielectric multilayer film. The first wavelength selective film 13c1 has, for example, an annular shape with a through-hole formed in its central region, and the region of the through-hole corresponds to the first region Ar1. The first wavelength selective film 13c1 can be disposed on the second region Ar2 by forming the first wavelength selective film 13c1 on the second antireflection film 13b so that the center of the first wavelength selective film 13c1 is aligned with the center of the second antireflection film 13b.

[0035] Fig. 7 is a graph showing the spectral reflectance of the first wavelength selective film 13c1 according to embodiment 1. As shown in Fig. 7, the spectral reflectance of the first wavelength selective film 13c1 is such that it reflects about 30% of the amount of light in the blue wavelength band of approximately 430 nm to 500 nm.

[0036] In the wavelength-selective filter 13, the average transmittance of the first light is 60% or more and 80% or less at a portion where the difference in transmittance with respect to the transmittance of the first light on the optical axis 11 is greatest.

[0037] According to the projection lens unit 9 of the first embodiment, even if part of the light in the red wavelength band is reflected due to the properties of the second antireflection film 13b in a region of the incident image light with a large angle of view, the first wavelength selective film 13c1 reflects part of the light in the blue wavelength band, thereby improving the uniformity of chromaticity. Furthermore, by reflecting part of the light in the blue wavelength band, which has a low relative luminous efficiency and little effect on illuminance, it is possible to improve the uniformity of chromaticity while suppressing a decrease in the brightness of the entire projected image.

[0038] [1-3. Effects, etc.] As described above, the projection lens unit 9 according to the first embodiment enlarges and projects image light, which is output from the image forming unit 7 and includes a first light and a second light having a wavelength band longer than that of the first light, onto the projection target, the screen 15. The projection lens unit 9 includes a plurality of lenses Ln1 to Ln5 coated with a first anti-reflection film 10, and a wavelength-selective filter 13 having a first region Ar1 in the center through which the optical axis passes and a second region Ar2 surrounding the first region Ar1. In the wavelength-selective filter 13, the second region Ar2 has a lower transmittance for the first light than the first region Ar1, and is lower than the transmittance for the second light.

[0039] As a result, even if part of the second light is reflected due to the properties of the second anti-reflection film 13b from the image light that passes through the second region of the projection lens unit 9, which has a large angle of view, the first wavelength selection film 13c1 reflects part of the first light, thereby improving the uniformity of the chromaticity of the image projected onto the screen 15.

[0040] Furthermore, the projection display device 1 according to the first embodiment includes the above-described projection lens unit 9, a light source unit 3 that irradiates light, and an image forming unit 7 that outputs image light using the light from the light source unit 3. This makes it possible to provide a projection display device 1 that can improve the uniformity of chromaticity of the image projected onto the screen 15.

[0041] Next, a modified example of the first embodiment will be described with reference to Figures 8 and 9. Figure 8 is a diagram showing the configuration of a projection display device 1A according to a modified example of embodiment 1. Figure 9 is a diagram showing the configuration of a wavelength-selective filter 13A according to a modified example of embodiment 1, with Figure 9(a) being a cross-sectional view of the wavelength-selective filter 13A and Figure 9(b) being a front view of the wavelength-selective filter 13A.

[0042] In the modified example of the first embodiment, the wavelength-selective filter 13A is formed on the surface of the lens Ln1 of the projection lens unit 9A. For example, as shown in FIG. 8, the wavelength-selective filter 13A may be formed on the entrance surface of the lens Ln1 closest to the image forming unit 7, or on the exit surface of the lens Ln1. Furthermore, the wavelength-selective filter 13A is not limited to being formed on the lens Ln1, but may also be formed on the entrance surface or exit surface of the lens Ln2 or Ln3 on the image forming unit 7 side. Furthermore, the wavelength-selective filter 13A may also be formed on the entrance surface or exit surface of any of the lenses Ln4 to Ln5 on the screen 15 side.

[0043] The wavelength-selective filter 13A includes a second anti-reflection film 13b formed on the incident surface of the lens Ln1 and a first wavelength-selective film 13c1 formed in a second region Ar2 around the first region Ar1 of the second anti-reflection film 13b.

[0044] Even with this configuration, the uniformity of chromaticity of the image projected onto the screen 15 can be improved, just like in the first embodiment.

[0045] (Embodiment 2) Next, a projection lens unit and a projection display device according to a second embodiment will be described with reference to Fig. 10. Fig. 10 shows the configuration of a wavelength-selective filter 13B according to the second embodiment, with Fig. 10(a) being a cross-sectional view of the wavelength-selective filter 13B and Fig. 10(b) being a front view of the wavelength-selective filter 13B.

[0046] The wavelength-selective filter 13B of the second embodiment has a second wavelength-selective film 13d1 arranged in the first region Ar1, whereas the wavelength-selective filter 13 of the first embodiment has a first wavelength-selective film 13c1 arranged in the second region Ar2. Except for this point and points described below, the projection lens unit and projection display device of the second embodiment have the same configuration as the projection lens unit and projection display device of the first embodiment.

[0047] The wavelength-selective filter 13B includes a second antireflection film 13b disposed in a first region Ar1 and a second region Ar2 on the incident surface of the transparent substrate 13a facing the image forming unit 7. The second antireflection film 13b has an annular exposed surface in a front view.

[0048] The wavelength-selective filter 13B also includes a second wavelength-selective film 13d1 having a lower transmittance for the second light than for the first light. The second wavelength-selective film 13d1 is disposed on a first region Ar1 of the second antireflection film 13b, which is disposed on the image forming unit 7 side of the transparent substrate 13a. The second wavelength-selective film 13d1 has a circular shape in a front view.

[0049] Fig. 11 is a graph showing the spectral reflectance of the second wavelength selective film 13d1 according to embodiment 2. As shown in Fig. 11, the spectral reflectance of the first wavelength selective film 13c1 is such that it reflects about 30% of the amount of light in the red wavelength band of approximately 600 nm to 670 nm.

[0050] In the wavelength-selective filter 13B, at a portion where the difference in transmittance with respect to the transmittance of the second light on the optical axis 11 is greatest, the average transmittance of the second light is 60% or more and 80% or less.

[0051] As described above, in the projection lens unit 9 equipped with the wavelength selective filter 13B of the second embodiment, the reflectance of the second light is higher in the first region Ar1 near the optical axis than in the peripheral second region Ar2, so the second light is reflected in the first region Ar1. Furthermore, the second light passing through the second region Ar2 is reflected by the first antireflection coatings 10 of the lenses Ln1 to Ln5, so the image light projected onto the screen 15 has an overall bluish hue, improving the uniformity of the chromaticity of the image. Because the second light near the periphery of the image is partially reflected by the first antireflection coatings 10 of the lenses Ln1 to Ln5, and the second light near the center of the image is partially reflected by the second wavelength selective film 13d1, the uniformity of the brightness of the entire projected image light can also be improved.

[0052] Also in the second embodiment, as in the modified example of the first embodiment, the wavelength-selective filter 13B may be formed on the entrance surface or exit surface of the lens Ln1 on the image forming unit 7 side of the projection lens unit 9A, or on the entrance surface or exit surface of the lens Ln5 on the screen 15 side. In this case, the wavelength-selective filter 13B is composed of a second anti-reflection film 13b formed on the surface of the lens Ln1, and a second wavelength-selective film 13d1 formed on this second anti-reflection film 13b.

[0053] (Embodiment 3) Next, a projection lens unit and a projection display device according to a third embodiment will be described with reference to Fig. 12. Fig. 12 shows the configuration of a wavelength-selective filter 13C according to the third embodiment, with Fig. 12(a) being a cross-sectional view of the wavelength-selective filter 13C and Fig. 12(b) being a front view of the wavelength-selective filter 13C.

[0054] The wavelength-selective filter 13C of the third embodiment is configured by combining the wavelength-selective filter 13 of the first embodiment with the wavelength-selective filter 13B of the second embodiment. Except for this point and points described below, the projection lens unit and the projection display device of the third embodiment have a common configuration with the projection lens unit and the projection display device of the first embodiment.

[0055] In the wavelength selective filter 13C, a second wavelength selective film 13d2 is disposed on a first region Ar1 on the image forming unit 7 side of the transparent substrate 13a, and a first wavelength selective film 13c2 is disposed on a second region Ar2 on the image forming unit 7 side of the transparent substrate 13a. Therefore, the second wavelength selective film 13d2 and the first wavelength selective film 13c2 are disposed side by side in the radial direction, and the first wavelength selective film 13c2 is disposed around the second wavelength selective film 13d2.

[0056] Fig. 13 is a graph showing the spectral reflectance of the first wavelength selective film 13c2 according to embodiment 3. As shown in Fig. 13, the spectral reflectance of the first wavelength selective film 13c2 is such that it reflects about 15% of the amount of light in the blue wavelength band of approximately 430 nm to 500 nm.

[0057] Fig. 14 is a graph showing the spectral reflectance of the second wavelength selective film 13d2 according to embodiment 3. As shown in Fig. 14, the spectral reflectance of the second wavelength selective film 13d2 is such that it reflects about 15% of the amount of light in the red wavelength band of approximately 600 nm to 670 nm.

[0058] As described above, with the projection lens unit 9 including the wavelength selective filter 13C of the third embodiment, even if a portion of the second light is reflected due to the properties of the first antireflection film 10 from the image light passing through the second region Ar2 having a large angle of view, the first wavelength selective film 13c2 reflects a portion of the first light, thereby improving the uniformity of the chromaticity of the image projected on the screen 15. Furthermore, because the reflectivity of the second light is higher in the first region Ar1 near the optical axis than in the surrounding second region Ar2, the second light is reflected in the first region Ar1. In this way, because a portion of the first light is reflected in the second region Ar2 and a portion of the second light is reflected in the first region Ar1, the amount of light reflected by each region can be reduced compared to the first and second embodiments. This improves the uniformity of the chromaticity of the image, and achieves a good balance between suppressing a decrease in the overall brightness of the projected image and reducing the difference in brightness between the center and periphery of the projected image.

[0059] Also in the third embodiment, as in the modified example of the first embodiment, the wavelength-selective filter 13C may be formed on the entrance surface or exit surface of the lens Ln1 on the image forming unit 7 side of the projection lens unit 9, or on the entrance surface or exit surface of the lens Ln5 on the screen 15 side. In this case, the wavelength-selective filter 13C is composed of a second wavelength-selective film 13d2 arranged on the first region Ar1 and a first wavelength-selective film 13c2 arranged on the second region Ar2.

[0060] (Other embodiments) (1) In the above-described embodiments, the first wavelength selective films 13c1 and 13c2 have the property of reflecting a portion of light in the blue wavelength band. However, they may also be films that absorb a portion of light in the blue wavelength band. In this case, increasing the thickness of the first wavelength selective films 13c1 and 13c2 reduces the transmittance of light in the blue wavelength band. Therefore, the spectral transmittance of the first wavelength selective films 13c1 and 13c2 may be gradually increased in the radial direction from the boundary with the second antireflection film 13b or the second wavelength selective film 13d1. This allows for more continuous uniformity of chromaticity from the center to the periphery of the projected image. Similarly, the second wavelength selective films 13d1 and 13d2 may also be films that absorb a portion of light in the red wavelength band. In this case, increasing the thickness of the second wavelength selective films 13d1 and 13d2 reduces the transmittance of light in the red wavelength band. Therefore, the spectral transmittance of the second wavelength selective films 13d1 and 13d2 may be changed stepwise along the radial direction by gradually increasing the thickness of the second wavelength selective films 13d1 and 13d2 from the boundary with the second antireflection film 13b or the first wavelength selective film 13dc2 toward the optical axis 11.

[0061] (2) In each of the above-described embodiments, the selective wavelength filter 13 is provided in the projection lens unit 9, but this is not limited to this. For example, as shown in FIG. 15 , the selective wavelength filter 13 may be disposed on the optical path between the image forming unit 7 and the projection lens unit 9 within the housing 8 of the projection display device 1B. The housing 8 houses the light source unit 3, the illumination optical system 5, the image forming unit 7, and the selective wavelength filter 13, and the projection lens unit 9 is detachably attached to the housing 8. The selective wavelength filter 13 is fixed to the housing 8.

[0062] Furthermore, the selective wavelength filter housed in the housing 8 is not limited to the selective wavelength filter 13 of the first embodiment, but may be the selective wavelength filter 13B of the second embodiment or the selective wavelength filter 13C of the third embodiment. Each of the selective wavelength filters can provide the above-mentioned effects.

[0063] As described above, the above-described embodiments have been described as examples of the technology of the present disclosure. For this purpose, the accompanying drawings and detailed description have been provided. Therefore, the components described in the accompanying drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to exemplify the above technology. Therefore, the fact that these non-essential components are described in the accompanying drawings or detailed description should not be interpreted as immediately indicating that these non-essential components are essential.

[0064] Furthermore, the technology in the present disclosure is not limited to the above-described embodiments, but can also be applied to embodiments in which modifications, substitutions, additions, omissions, etc. Furthermore, it is also possible to combine the components described in the above-described embodiments to create new embodiments.

[0065] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0066] (Outline of the embodiment) (1) A projection lens unit according to the present disclosure is a projection lens unit that enlarges and projects image light, which is output from an image forming unit and includes a first light and a second light having a wavelength band longer than that of the first light, onto a projection target. The projection lens unit includes a plurality of lenses coated with a first anti-reflection film, and a wavelength-selective filter having a first central region through which an optical axis passes and a second region surrounding the first region. In the wavelength-selective filter, the transmittance of the first light in the second region is lower than the transmittance of the first light in the first region.

[0067] The lenses coated with the first anti-reflection film reduce the transmittance of the second light passing through the second region to be lower than the transmittance of the first light, but the wavelength-selective filter reduces the transmittance of the first light passing through the second region, thereby improving the color uniformity of the image light projected onto the projection target and preventing a decrease in the overall brightness of the projected image light.

[0068] (2) In the projection lens unit of (1), the transmittance of the second light in the first region of the wavelength selective filter is lower than the transmittance of the second light in the second region. This prevents a decrease in the overall brightness of the projected image light, reduces the difference in brightness between the center and periphery of the projected image light, and improves the color uniformity of the projected image light.

[0069] (3) The present disclosure also provides a projection lens unit that enlarges and projects image light, which is output from an image forming unit and includes a first light and a second light having a wavelength band longer than that of the first light, onto a projection target. The projection lens unit includes a wavelength-selective filter having a first region at the center through which an optical axis passes and a second region surrounding the first region. In the wavelength-selective filter, the transmittance of the second light in the first region is lower than the transmittance of the second light in the second region.

[0070] The plurality of lenses coated with the first anti-reflection film reduces the transmittance of the second light passing through the second region, but the wavelength selective filter also reduces the transmittance of the second light passing through the first region, so that the transmittance of the second light for the image light can be reduced overall, improving the color uniformity of the projected image light. In addition, because the transmittance of the second light is reduced in both the first region and the second region, the difference in brightness between the center and periphery of the projected image light can also be reduced.

[0071] (4) In any one of the projection lens units (1) to (3), the wavelength selection filter is disposed on the image forming unit side or the projection target side of the projection lens unit.

[0072] (5) In any one of the projection lens units (1) to (4), the wavelength selection filter is formed on the light entrance or exit surface of the lens on the image forming unit side of the projection lens unit, or on the light entrance or exit surface of the lens on the projection target side.

[0073] (6) In any one of the projection lens units (1) to (5), the spectral transmittance of the wavelength-selective filter changes rotationally symmetrically about the optical axis of the projection lens unit.

[0074] (7) In the projection lens unit of (1), the wavelength selective filter has an average transmittance of the first light of 60% or more and 80% or less at the point where the difference in transmittance is greatest with respect to the transmittance of the first light on the optical axis.

[0075] (8) In the projection lens unit of (3), the wavelength selective filter has an average transmittance of the second light of 60% or more and 80% or less at the point where the difference in transmittance is greatest with respect to the transmittance of the second light on the optical axis.

[0076] (9) In the projection lens unit of (1), the wavelength selective filter is disposed in the second region and includes a first wavelength selective film having a lower transmittance for the first light than for the second light.

[0077] (10) In the projection lens unit of (2), the wavelength selection filter comprises a first wavelength selection film arranged in the second region and having a lower transmittance for the first light than for the second light, and a second wavelength selection film arranged in the first region and having a lower transmittance for the second light than for the first light.

[0078] (11) In the projection lens unit of (3), the wavelength selective filter is provided with a second wavelength selective film disposed in the first region and having a lower transmittance for the second light than for the first light.

[0079] (12) In the projection lens unit of (9), the wavelength selective filter is arranged in the first region and the second region and has an anti-reflection film that is circular when viewed from the front, and the first wavelength selective film has an annular shape when viewed from the front and is arranged on the anti-reflection film.

[0080] (13) In the projection lens unit of (11), the wavelength selective filter is arranged in the first region and the second region and has an anti-reflection film that is circular in front view, and the second wavelength selective film has a circular shape in front view and is arranged on the anti-reflection film.

[0081] (14) In the projection lens unit of (9), the spectral transmittance of the first wavelength selective film of the wavelength selective filter changes stepwise along the radial direction.

[0082] (15) In the projection lens unit of (10), the spectral transmittance of the first and second wavelength selective films of the wavelength selective filter changes stepwise along the radial direction.

[0083] (16) In the projection lens unit of (11), the spectral transmittance of the second wavelength selective film of the wavelength selective filter changes stepwise along the radial direction.

[0084] (17) In the projection lens unit of any one of (1) to (16), the first light is light in a wavelength band of 430 nm or more and 500 nm or less, and the second light is light in the visible light band.

[0085] In the projection lens unit of (18) and (17), the second light is light in a wavelength band of 600 nm or more and 670 nm or less.

[0086] (19) In the projection lens unit of any one of (1) to (18), the projection lens unit has a maximum angle of view of 60 degrees or more.

[0087] (20) A projection display device according to the present disclosure includes a projection lens unit selected from any one of (1) to (19), a light source unit that emits light, and an image forming unit that outputs image light using the light from the light source unit.

[0088] (21) A projection display device according to the present disclosure includes a light source unit that emits light, an image forming unit that uses the light from the light source unit to output image light including a first light and a second light having a wavelength band longer than the first light, a projection lens unit that enlarges and projects the image light output from the image forming unit onto a projection target, and a wavelength selective filter disposed on an optical path between the image forming unit and the projection lens unit. The projection lens unit has multiple lenses coated with a first anti-reflection film. The wavelength selective filter has a first central region through which an optical axis passes and a second region surrounding the first region, and the transmittance of the first light in the second region is lower than the transmittance of the first light in the first region.

[0089] (22) A projection display device according to the present disclosure includes a light source unit that emits light, an image forming unit that uses the light from the light source unit to output image light including a first light and a second light having a wavelength band longer than the first light, a projection lens unit that enlarges and projects the image light output from the image forming unit onto a projection target, and a wavelength selective filter disposed on an optical path between the image forming unit and the projection lens unit. The projection lens unit has multiple lenses coated with a first anti-reflection film. The wavelength selective filter has a first central region through which an optical axis passes and a second region surrounding the first region, and the transmittance of the second light in the first region is lower than the transmittance of the second light in the second region. [Industrial Applicability]

[0090] The present disclosure is applicable to a projection lens unit that enlarges and projects image light onto a projection target, and to a projection display device. [Explanation of symbols]

[0091] 1 Projection display device 3 Light source section 5 Illumination optical system 7 Image forming unit 9 Projection lens unit 10 First anti-reflection coating 11 Optical axis 13, 13B Wavelength selection filter 13a Transparent substrate 13b Second anti-reflection coating 13c1, 13c2 First wavelength selective film 13d1, 13d2 Second wavelength selective film 15 screens Ar1 First area Ar2 Second Area Ln1~Ln5, Ln11~Ln20 lenses

Claims

1. a projection lens unit that projects, onto a projection target, image light output from an image forming unit, the image light including first light and second light having a wavelength band longer than that of the first light, in an enlarged manner, the projection lens unit comprising: a plurality of lenses coated with a first anti-reflection coating; a wavelength-selective filter having a first central area through which an optical axis passes and a second central area surrounding the first central area; In the wavelength selective filter, the transmittance of the first light in the second region is lower than the transmittance of the first light in the first region, and the average transmittance of the first light is 60% or more and 80% or less at a location where the difference in transmittance with respect to the transmittance of the first light on the optical axis is the largest. Projection lens unit.

2. In the wavelength selective filter, the transmittance of the second light in the first region is lower than the transmittance of the second light in the second region.

2. The projection lens unit according to claim 1.

3. a projection lens unit that projects, onto a projection target, image light output from an image forming unit, the image light including first light and second light having a wavelength band longer than that of the first light, in an enlarged manner, the projection lens unit comprising: a plurality of lenses coated with a first anti-reflection coating; a wavelength-selective filter having a first central area through which an optical axis passes and a second central area surrounding the first central area; In the wavelength selective filter, the transmittance of the second light in the first region is lower than the transmittance of the second light in the second region, The wavelength selective filter is a second wavelength selective film disposed in the first region and having a lower transmittance for the second light than for the first light; a second anti-reflection film that is disposed in the first region and the second region and has a circular shape in a front view, the second wavelength selective film has a circular shape in a front view and is disposed on the second antireflection film; Projection lens unit.

4. In the wavelength selective filter, the average transmittance of the second light is 60% or more and 80% or less at a point where the difference in transmittance with respect to the transmittance of the second light on the optical axis is the largest.

4. The projection lens unit according to claim 3.

5. the wavelength selective filter is disposed in the second region and includes a first wavelength selective film having a lower transmittance for the first light than for the second light; 2. The projection lens unit according to claim 1.

6. The wavelength selective filter is a first wavelength selective film disposed in the second region and having a lower transmittance for the first light than for the second light; a second wavelength selective film disposed in the first region and having a lower transmittance for the second light than for the first light; 3. The projection lens unit according to claim 2.

7. a projection lens unit that projects, onto a projection target, image light output from an image forming unit, the image light including first light and second light having a wavelength band longer than that of the first light, in an enlarged manner, the projection lens unit comprising: a plurality of lenses coated with a first anti-reflection coating; a wavelength-selective filter having a first central area through which an optical axis passes and a second central area surrounding the first central area; In the wavelength-selective filter, the transmittance of the first light in the second region is lower than the transmittance of the first light in the first region, The wavelength selective filter is a first wavelength selective film disposed in the second region and having a lower transmittance for the first light than for the second light; a second anti-reflection film that is disposed in the first region and the second region and has a circular shape in a front view, the first wavelength selective film has an annular shape in a front view and is disposed on the second antireflection film; Projection lens unit.

8. the spectral transmittance of the first wavelength selective film of the wavelength selective filter changes stepwise along the radial direction; 6. The projection lens unit according to claim 5.

9. the spectral transmittance of the first and second wavelength selective films of the wavelength selective filter changes stepwise along the radial direction; 7. The projection lens unit according to claim 6.

10. the spectral transmittance of the second wavelength selective film of the wavelength selective filter changes stepwise along the radial direction; 4. The projection lens unit according to claim 3.

11. a projection lens unit that projects, onto a projection target, image light output from an image forming unit, the image light including first light and second light having a wavelength band longer than that of the first light, in an enlarged manner, the projection lens unit comprising: a plurality of lenses coated with a first anti-reflection coating; a wavelength-selective filter having a first central area through which an optical axis passes and a second central area surrounding the first central area; In the wavelength-selective filter, the transmittance of the first light in the second region is lower than the transmittance of the first light in the first region, The projection lens unit has a maximum angle of view of 60 degrees or more. Projection lens unit.

12. a projection lens unit that projects, onto a projection target, image light output from an image forming unit, the image light including first light and second light having a wavelength band longer than that of the first light, in an enlarged manner, the projection lens unit comprising: at least one lens coated with a first anti-reflective coating; a wavelength-selective filter having a first region through which an optical axis passes and a second region surrounding the first region; In the wavelength selective filter, the average transmittance of the first light is 60% or more and 80% or less at a location in the second region where the difference in transmittance with respect to the transmittance of the first light on the optical axis is the largest. Projection lens unit.

13. a projection lens unit that projects, onto a projection target, image light output from an image forming unit, the image light including first light and second light having a wavelength band longer than that of the first light, in an enlarged manner, the projection lens unit comprising: at least one lens coated with a first anti-reflective coating; a wavelength-selective filter having a first central area through which an optical axis passes and a second central area surrounding the first central area; In the wavelength selective filter, the transmittance of the second light in the first region is lower than the transmittance of the second light in the second region, The wavelength selective filter is a second wavelength selective film disposed in the first region and having a lower transmittance for the second light than for the first light; a second anti-reflection film that is disposed in the first region and the second region and has a circular shape in a front view, the second wavelength selective film has a circular shape in a front view and is disposed on the second antireflection film; Projection lens unit.

14. A projection lens unit according to any one of claims 1 to 13; a light source unit that irradiates light; the image forming unit outputs the image light using light from the light source unit, Projection display device.

15. a light source unit that irradiates light; an image forming unit that outputs image light including first light and second light having a wavelength band longer than that of the first light, using light from the light source unit; a projection lens unit that enlarges and projects the image light output from the image forming unit onto a projection target; a wavelength selection filter disposed on an optical path between the image forming unit and the projection lens unit, the projection lens unit has a plurality of lenses coated with a first anti-reflection film; the wavelength-selective filter has a first region at the center through which an optical axis passes and a second region surrounding the first region, and the transmittance of the first light in the second region is lower than the transmittance of the first light in the first region; In the wavelength selective filter, the average transmittance of the first light is 60% or more and 80% or less at a portion where the difference in transmittance with respect to the transmittance of the first light on the optical axis is the largest. Projection display device.

16. a light source unit that irradiates light; an image forming unit that outputs image light including first light and second light having a wavelength band longer than that of the first light, using light from the light source unit; a projection lens unit that enlarges and projects the image light output from the image forming unit onto a projection target; a wavelength selection filter disposed on an optical path between the image forming unit and the projection lens unit, the projection lens unit has a plurality of lenses coated with a first anti-reflection film; the wavelength-selective filter has a first region at the center through which an optical axis passes and a second region surrounding the first region, and the transmittance of the second light in the first region is lower than the transmittance of the second light in the second region; The wavelength selective filter is a second wavelength selective film disposed in the first region and having a lower transmittance for the second light than for the first light; a second anti-reflection film that is disposed in the first region and the second region and has a circular shape in a front view, the second wavelength selective film has a circular shape in a front view and is disposed on the second antireflection film; Projection display device.

Images