JP3723409B2 - Wavelength selection element and display device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wavelength selection element and a display device using the same, and more particularly to a notch filter that selectively removes light in a specific wavelength band and a display device using the notch filter.
[0002]
[Prior art]
As a display device for a large screen, there is a projection type image display device (hereinafter referred to as “projector”). The projector performs display by enlarging and projecting light emitted from a light source and modulated by an image display element onto a screen using a projection lens.
[0003]
A transmissive projector (FIGS. 11 and 12) using a transmissive image display element as an image display element and a reflective projector (FIGS. 13 and 14) using a reflective image display element as an image display element are known.
[0004]
The structure of the conventional transmissive projector shown in FIG. 11 will be described.
[0005]
The light emitted directly from the light source 121 or through the reflector transmits blue light and reflects green light and red light, a dichroic mirror 123 that reflects green light and transmits red light, and The total reflection mirror 127 separates the light into three primary colors of red, green, and blue. Each color light passes through the liquid crystal light valves (liquid crystal display elements) 126R, 126G, and 126B, and then reflects the total reflection mirror 128, the dichroic mirror 124 that reflects green light and transmits blue light, and reflects red light and reflects green light. It is again synthesized by the dichroic mirror 125 that transmits light and blue light. The combined light is projected on a screen (not shown) by the projection lens 129.
[0006]
The structure of another conventional transmissive projector shown in FIG. 12 is basically the same as that of the projector shown in FIG. Light emitted directly from the light source 134 or through the reflector transmits blue light, reflects green light and red light, a dichroic mirror 133 that reflects green light and transmits red light, and The total reflection mirror 136 separates the light into three primary colors of red, green, and blue. The three primary colors transmitted through the liquid crystal light valves 131R, 131G, and 131B are combined again by the cross dichroic prism 130, and the combined light is projected onto the screen by the projection lens 135.
[0007]
Next, the structure of a conventional projector using a reflective display element will be described.
[0008]
The reflective projector shown in FIG. 13 is disclosed in an electronic display forum 97 (P.3-27 to 3-32). In this projector, light emitted from a light source 141 is separated into light of three primary colors of red, green, and blue (hereinafter, referred to as R, G, and B in order) by a dichroic mirror, and each light is correspondingly polarized. The light is incident on a beam splitter (hereinafter referred to as “PBS”) 142. In the PBS 142, the incident light is separated into two linearly polarized light components whose polarization directions are orthogonal to each other, and one light is incident on the corresponding reflective liquid crystal display element 144. The R, G, and B lights reflected by the reflective liquid crystal display element 144 and whose polarization directions are modulated are incident on the PBS 142 again, synthesized by the cross dichroic prism 143, and then projected on the screen by the projection lens 145. .
[0009]
A reflection type projector shown in FIGS. 14A and 14B is disclosed in Japanese Patent Laid-Open No. 4-338721. As shown in FIGS. 14A and 14B, the light from the light source is separated into two linearly polarized light by PBS 155, and then one of the lights is color-separated and combined by a cross dichroic prism (FIG. 14A) or a Philips type prism (FIG. 14B). The light is separated into R, G, and B light by the element, and the light reflected by the reflective liquid crystal display element is color-combined by the same element, and then incident again on the PBS 155, and only the light whose polarization direction is modulated is applied to the projection lens 158. Incident and projected onto the screen.
[0010]
The above-described conventional projectors are all called three-plate liquid crystal projectors, and can use R, G, and B light from a light source efficiently, so that a very bright image can be realized.
[0011]
On the other hand, although not described in detail here, a single-panel projector that realizes color display by combining a lens and a dichroic mirror or using a color filter with a single liquid crystal display element is also used. .
[0012]
A conventional projector using a liquid crystal display element as an image display element has been described. Of course, as in a digital micromirror device (DMD), there are various methods such as controlling the angle of micromirrors arranged in a matrix. There are types of projectors.
[0013]
As a light source for these projectors, a metal halide lamp, a high-pressure mercury lamp, a xenon lamp, or the like that has a continuous emission spectrum over the entire wavelength range of visible light is generally used.
[0014]
FIG. 15 shows an emission spectrum of a metal halide lamp, for example. The emission spectrum of the metal halide lamp includes several bright lines. Light having an intensity peak between about 400 nm and 480 nm is used as blue light. Further, light having an intensity peak between about 490 nm and 550 nm is used as green light, and light having an intensity peak between about 620 nm and 700 nm is used as red light.
[0015]
On the other hand, light having an energy peak in the vicinity of a wavelength of 580 nm is yellow light or amber light, and adversely affects the color reproduction of a projection image projected by the projector. Specifically, when this light is incident on the red liquid crystal display element together with the red light and projected onto the screen, the projected image that should originally be red becomes orange. Further, when this light is incident on the green liquid crystal display element together with the green light and projected onto the screen, the projected image that should originally be green becomes yellowish green. For this reason, when importance is attached to the color reproducibility (color purity) of the projection image projected by the projector, light having an energy peak in the vicinity of the wavelength of 580 nm must be removed from the light emitted from the light source.
[0016]
An optical element (wavelength selection element) that removes only light near a certain wavelength is called a notch filter. For example, Japanese Patent Application Laid-Open No. 11-249098 discloses a projector using a notch filter.
[0017]
[Problems to be solved by the invention]
However, the conventional notch filter is generally a dielectric multilayer film formed by a thin film multilayer deposition technique and has, for example, a spectral transmittance characteristic as shown in FIG.
[0018]
When this dielectric multilayer film is used to cut only light in an arbitrary wavelength range, the spectral transmittance characteristics of the dielectric multilayer film having a practical number of layers are not steep and gentle in the cut wavelength range. Become. For this reason, if the wavelength range to be cut is to be completely cut, it is necessary to superimpose several filters. By doing so, the light in the required wavelength range is also sacrificed and the projected image becomes dark. End up.
[0019]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wavelength selection element having better performance than a conventional notch filter and to use such a wavelength selection element. An object of the present invention is to provide a display device that is bright and excellent in color reproducibility.
[0020]
[Means for Solving the Problems]
The wavelength selection element of the present invention includes a first polarization regulating element that changes a polarization state of light in a first wavelength range and a second polarization regulation element that changes a polarization state of light in a second wavelength range different from the first wavelength range. And a pair of polarization selection elements that are arranged so as to face each other via the plurality of polarization restriction elements, and each selectively transmits or reflects light of a specific polarization direction. To achieve the above object.
[0021]
The first wavelength region and the second wavelength region are at least partially overlapped with each other, and the first and second polarization regulating elements are λ / s with respect to light in the first wavelength region and the second wavelength region, respectively. It preferably functions as two plates.
[0022]
Each of the pair of polarization selection elements may be arranged so that polarization axes of light that is selectively transmitted or reflected are substantially parallel to each other.
[0023]
Another wavelength selection element according to the present invention includes a first polarization regulating element that changes a polarization state of light in a first wavelength range and a second polarization that changes a polarization state of light in a second wavelength range different from the first wavelength range. A plurality of polarization regulating elements including at least a regulating element, and a polarization selection that selectively transmits or reflects light of a reflecting element and a specific polarization direction arranged so as to face each other via the plurality of polarization regulating elements And the above object is achieved.
[0024]
The first wavelength region and the second wavelength region are at least partially overlapped with each other, and the first and second polarization regulating elements are λ / s with respect to light in the first wavelength region and the second wavelength region, respectively. It preferably functions as four plates.
[0025]
The display device of the present invention includes any one of the wavelength selection elements described above, thereby achieving the above object.
[0026]
Another display device of the present invention is a light source, a polarization selection element that selectively transmits or reflects light in a specific polarization direction of light emitted from the light source, and modulates the polarization selected by the polarization selection element And a projection optical element that projects the polarized light modulated by the display element, and a plurality of polarization regulating elements and a further polarization selection element are provided in this order on the light output side of the polarization selection element. The plurality of polarization regulating elements include a first polarization regulating element that changes a polarization state of light in a first wavelength range, and a second polarization that changes a polarization state of light in a second wavelength range different from the first wavelength range. Including at least a regulating element, whereby the above object is achieved.
[0027]
The first wavelength region and the second wavelength region partially overlap each other, and the first and second polarization regulating elements are λ / 2 with respect to light in the first wavelength region and the second wavelength region, respectively. It preferably functions as a plate.
[0028]
The operation of the present invention will be described below.
[0029]
The first polarization regulating element included in the wavelength selection element of the present invention changes the polarization state of light in the first wavelength range, and the second polarization regulation element changes the polarization state of light in the second wavelength range. Since the first wavelength range and the second wavelength range are different from each other, the polarization state of the light transmitted through the first and second polarization regulating elements differs depending on the wavelength range. For example, the polarization state is different between light in a wavelength region that is not included in either the first wavelength region or the second wavelength region and light in the first wavelength region or the second wavelength region. Furthermore, the polarization state of the light in the wavelength region where the first wavelength region and the second wavelength region overlap is different from the polarization state of the light in any wavelength region described above. Since the first and second polarization regulating elements are provided between a pair of polarization selecting elements (for example, polarizing plates), various wavelength regions in different polarization states by the first and second polarization regulating elements. Only light in a wavelength region in a specific polarization state can pass through the wavelength selection element. That is, the difference in polarization state depending on the wavelength region is converted into a difference in transmittance, and functions as a wavelength selection element.
[0030]
Of course, the number of polarization regulating elements is not limited, and a third polarization regulating element or the like that changes the polarization state of light in the third wavelength region may be provided as necessary. In the case where three or more polarization regulating elements are provided, the wavelength regions where each polarization regulating element acts have different polarization states in the respective common wavelength regions and the other wavelength regions. Thus, the difference in polarization state is converted into a difference in transmittance, and functions as a wavelength selection element.
[0031]
The spectral characteristics of the polarization-regulating element (the spectral characteristics of the boundary region of the wavelength range that changes the polarization state) are steeper than the spectral transmittance characteristics of the conventional notch filter formed from the dielectric multilayer film. The spectral transmittance characteristic of the wavelength selection element is superior to that of a conventional notch filter. As the polarization-regulating element of the wavelength selection element of the present invention, for example, an element using a retardation plate stacking technique disclosed in SID'99, Vo 1.30, p1072 (referred to as a “multilayer retardation layer element”). Alternatively, an element using a cholesteric liquid crystal can be used.
[0032]
The first wavelength region and the second wavelength region are set so as to at least partially overlap each other, and each of the first and second polarization regulating elements is λ / with respect to the light in the first wavelength region and the second wavelength region. When the structure that functions as two plates is adopted, light in the wavelength region where the wavelength regions where the two polarization regulating elements act overlaps the two λ / 2 plates, and the two polarization regulating elements are The light in the wavelength range where each acts independently (the wavelength range where the two wavelength ranges do not overlap) passes through one λ / 2 plate, and the wavelength range where neither of the two polarization regulating elements acts. Is equivalent to not passing through the λ / 2 plate. Accordingly, polarization of light in a wavelength region in which each of the two polarization regulating elements acts independently (that is, a wavelength region including a first wavelength region and a second wavelength region, excluding overlapping wavelength regions). Only the direction is rotated by 90 ° with respect to the polarization direction of light in other wavelength ranges, and a notch filter with better performance can be obtained.
[0033]
By arranging the polarization axes of light transmitted or reflected by the pair of polarization selection elements substantially in parallel, light in a wavelength region where the polarization regulating element does not act is almost transmitted, so that a brighter and better performance notch filter can be obtained. can get.
[0034]
While the above-described wavelength selection element is a transmission-type notch filter, the first and second polarization regulating elements are disposed between the polarization selection element and the reflection element (for example, a reflection mirror), thereby providing a reflection type. A notch filter can be obtained.
[0035]
In the reflective notch filter, the first wavelength region and the second wavelength region are set so as to partially overlap each other, and as the first and second polarization regulating elements, for the light in the first wavelength region and the second wavelength region If each of them adopts a structure that functions as a λ / 4 plate, the incident light is reflected by the reflecting element, and therefore, the light in the wavelength region where the wavelength regions where the two polarization regulating elements act are overlapped by four λ / The light in the wavelength range (wavelength range in which the two wavelength ranges do not overlap) in which each of the two polarization regulating elements acts independently is transmitted through four plates (two λ / 2 plates). Light in a wavelength region where both of the two polarization regulating elements do not act is equivalent to not transmitting through the λ / 4 plate because it passes through the λ / 4 plate (one λ / 2 plate). . Accordingly, polarization of light in a wavelength region in which each of the two polarization regulating elements acts independently (that is, a wavelength region including a first wavelength region and a second wavelength region, excluding overlapping wavelength regions). Since only the direction is rotated 90 ° with respect to the polarization direction of the light in the other wavelength region and returned, it cannot pass through the polarization selection element, and a reflective notch filter with better performance can be obtained.
[0036]
By using the wavelength selection element described above, light in the wavelength range that lowers the color purity of the light from the light source can be removed more efficiently than a conventional notch filter using a dielectric multilayer film. A good image display device can be obtained. Although the wavelength selection element (notch filter) according to the present invention is preferably used for a projector, it goes without saying that it can also be used for a direct-view image display device.
[0037]
For example, a projection display device that performs display using polarized light, such as a liquid crystal projector, essentially includes a polarization selection element. Therefore, one of the polarization selection elements included in the wavelength selection element according to the present invention is shared (omitted). be able to. By adopting such a configuration, the number of polarization selection elements can be reduced, so that in addition to the improvement in color purity, the light utilization efficiency is increased and bright projection display is possible.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments.
[0039]
(Embodiment 1)
FIG. 1 is a schematic diagram of a wavelength selection element (notch filter) 1 according to Embodiment 1 of the present invention. The notch filter 1 includes a first polarization regulating element 12 and a second polarization regulating element 13, and a pair of polarizing plates 11 and 14 provided so as to sandwich them. The polarizing plates 11 and 14 are arranged so that the polarization axes of transmitted light are both perpendicular to the paper surface (parallel Nicols). As the polarization selection element, in addition to the polarizing plate (including the polarization film), a reflection type polarization element such as a polarization beam splitter (PBS) or DBEF (manufactured by Sumitomo 3M Co., Ltd., polarization selective reflection element) can be used.
[0040]
As the polarization regulating elements 12 and 13, the multilayer retardation layer element described above is used. The multilayer retardation layer element is commercially available from Color Link under the trade name “Color Select”, and the notch filter 1 of Embodiment 1 has color select 12 and 13.
[0041]
The color selectors 12 and 13 selectively function as λ / 2 plates for light in a specific wavelength range. FIG. 2 shows spectral transmittance characteristics when the color selectors 12 and 13 are arranged between a pair of polarizing plates arranged in parallel Nicols. A curve 21 in FIG. 2 indicates the spectral transmittance of the color select 12, and a curve 22 indicates the spectral transmittance of the color select 13. FIG. 3 shows spectral transmittance characteristics when the color select 12 and 13 are arranged between a pair of polarizing plates arranged in crossed Nicols. A curve 31 in FIG. 3 indicates the spectral transmittance of the color select 12, and a curve 32 indicates the spectral transmittance of the color select 13. As can be seen from FIGS. 2 and 3, the color select 12 rotates the polarization direction of the light in the wavelength region 23 by 90 °, and the color select 13 rotates the polarization direction of the light in the wavelength region 24 by 90 °. The wavelength range is based on the wavelength at which the relative transmittance is 50%.
[0042]
Therefore, the notch filter 1 provided between the polarizing plates 11 and 14 in which the color selects 12 and 13 having the above-described spectral characteristics are arranged in parallel Nicols functions as follows.
[0043]
The linearly polarized light that has been transmitted through the polarizing plate 11 is transmitted through the color select 12 so that only the polarization direction of light in the wavelength region 23 is rotated by 90 °. Further, by passing through the color select 13, only the polarization direction of light in the wavelength region 24 is further rotated by 90 °. Since part of the wavelength band 24 is completely overlapped with the wavelength band 23, the light in the wavelength band 23 is further polarized by 90 ° by the color select 13, and is the same polarized light as the linearly polarized light transmitted through the polarizing plate 11. Direction. Accordingly, by passing through the color selectors 12 and 13, only the polarization direction of the light in the wavelength region 25 is rotated by 90 ° with respect to the polarization direction of the light in the other wavelength regions. When this light enters the polarizing plate 14 arranged in a parallel Nicol state with the polarizing plates 11 and 14, only the light in the wavelength region 25 whose polarization direction is rotated by 90 ° is absorbed by the polarizing plate 14. Therefore, the wavelength selection element (notch filter) 1 having the spectral transmittance characteristic as shown in FIG. 4 is obtained.
[0044]
It is clear if the spectral transmittance characteristics of the notch filter 1 of the present embodiment shown in FIG. 4 are compared with the spectral transmittance characteristics of the conventional notch filter formed of the conventional dielectric multilayer film shown in FIG. As described above, the spectral transmittance characteristics of the notch filter 1 of the present embodiment are very steep. This is because the polarization regulating elements 12 and 13 have steep spectral characteristics as shown in FIGS. Thus, the notch filter 1 having a steep spectral transmittance characteristic can be obtained by using a polarization regulating element having a steep spectral characteristic and combining those spectral characteristics (wavelength range) well. Of course, the arrangement of the color selects 12 and 13 may be reversed.
[0045]
In addition, the wavelength selection element of embodiment by this invention can comprise various notch filters. For example, when the transmission axes (also referred to as “polarization axes”) of two polarization selection elements are arranged in crossed Nicols, a notch filter that selectively transmits only light in the wavelength region that has been cut by the notch filter 1 is configured. can do. Further, the dynamic range of the spectral transmittance and the value of the transmittance can be changed by changing the relative arrangement of the transmission axes of the pair of polarization selection elements.
[0046]
Further, the amount of light to be cut (transmittance) can be adjusted by changing the phase difference (equivalent to retardation; corresponding to λ / 2 in the above example) of the polarization regulating element. Furthermore, the wavelength range of the light to be cut can be changed by changing the wavelength range of the light on which the polarization regulating element acts. For example, when a multilayer retardation layer element such as the above-described color select is used, the retardation can be designed freely.
[0047]
Next, the structure of the projector according to the present embodiment will be described.
[0048]
The projector of this embodiment shown in FIG. 5 is provided with the above-described notch filter 1 in addition to the conventional projector projector of the dichroic prism type.
[0049]
White light emitted from the white light source 64 is separated into, for example, two colors of blue and yellow (red + green) by the dichroic mirror 62. The B light passes through the total reflection mirror 66 and enters the liquid crystal display element 61B that displays a blue color signal component. On the other hand, the yellow light is further separated into R light and G light by the dichroic mirror 63, and enters the liquid crystal display elements 61R and 61G that display images based on the red and green color signals, respectively.
[0050]
Light incident on the liquid crystal display elements 61R, 61G, and 61B is modulated in accordance with a signal corresponding to each pixel and is incident on the cross dichroic prism 60. The cross dichroic prism 60 combines the color lights emitted from the respective liquid crystal display elements 61R, 61G, and 61B, and the combined color lights are projected onto a screen (not shown) by the projection lens 65.
[0051]
In this projector, as shown in FIG. 5, light in the boundary wavelength region between red and green is efficiently removed by the notch filter 1 arranged on the optical path of the reflected light of the dichroic mirror 62. A projected image with excellent color reproducibility can be displayed.
[0052]
Of course, it may be arranged anywhere as long as it is on the optical path including light in the wavelength range to be cut. Further, since the light transmitted through the notch filter 1 of the present embodiment is linearly polarized light, the arrangement angle of the optical axis (slow axis) of the notch filter 1 is set according to the polarization state of the light on the optical path where the notch filter 1 is arranged. By adjusting, the amount of light transmitted through the notch filter 1 can be adjusted.
[0053]
In the present embodiment, as shown in FIG. 1, the notch filter 1 in which the two polarization regulating elements and the two polarization selection elements are integrated is used. They may be separated and arranged on the optical system in a predetermined order.
[0054]
In the above description, a transmissive liquid crystal display element is used, but it goes without saying that an optical system using a reflective display element can also be used in this system. The reflective display element includes a liquid crystal display element using liquid crystal and a display element such as a digital micromirror device (DMD) that does not use liquid crystal. As the liquid crystal display element, various modes such as a mode using the birefringence of liquid crystal and a mode not using birefringence such as a polymer dispersion method can be used.
[0055]
In the present embodiment, since the polarization regulating element that operates in a certain wavelength range or more is used, the wavelength range of the light to be cut is one, but a certain wavelength range (a part of the wavelengths within the visible wavelength range). It goes without saying that the number of wavelength regions of light to be cut can be arbitrarily designed by using a polarization regulating element that acts only on the region.
[0056]
(Embodiment 2)
FIG. 6 is a schematic diagram of a wavelength selection element (reflection notch filter) 70 according to Embodiment 2 of the present invention. The notch filter 70 includes a first polarization restricting element 72 and a second polarization restricting element 73, and a polarizing plate 71 and a reflecting mirror 74 provided so as to sandwich them. The polarizing axis of the light transmitted through the polarizing plate 71 is arranged to be perpendicular to the paper surface. As the polarization selection element, a polarizing beam splitter (PBS) or the like can be used in addition to the polarizing plate (including the polarizing film). The incident light 75 transmitted through the polarizing plate 71 is reflected by the reflecting mirror 74 and enters the polarizing plate 71 again. Therefore, the polarizing plate 71 is arranged in parallel Nicols with the polarization regulating elements 72 and 73 interposed therebetween. It functions equivalently to a pair of polarizing plates.
[0057]
As the polarization regulating elements 72 and 73, a color select manufactured by Color Link Co., Ltd. is used similarly to the notch filter 1 of the first embodiment. However, each color select 72 and 73 uses what functions as a λ / 4 plate for light in each wavelength region. That is, the reflective notch filter 70 functions in the same manner as the notch filter 1 of the first embodiment by the incident light 75 being reflected by the total reflection mirror 74 and reciprocating. That is, a reflective notch filter 70 having a spectral reflectance characteristic corresponding to the spectral transmittance characteristic of the notch filter 1 is obtained.
[0058]
FIG. 7 schematically shows the projector of this embodiment. This projector includes a white light source 84, dichroic mirrors 82 and 83, a total reflection mirror 86, three liquid crystal display elements 81R, 81G and 81B, a cross dichroic prism 80, a projection lens 85, and a reflective notch filter 70. The projector of the second embodiment shown in FIG. 7 has basically the same configuration as the projector of the first embodiment shown in FIG. 5, but does not use the notch filter 1 in the first embodiment, and the R in the projector of FIG. Instead of the total reflection mirror 66 arranged for the light, the reflection type notch filter 70 of the present embodiment is used. Of course, the present invention is not limited to this example, and the optical system may be arranged in another configuration.
[0059]
Since the projector according to the present embodiment also efficiently removes light in the boundary wavelength region between red and green by the reflective notch filter 70, the projection image is bright and excellent in color reproducibility, similar to the projector according to the first embodiment. Can be displayed.
[0060]
As in the first embodiment, the spectral characteristics of the notch filter 70 can be variously changed and various display elements can be used without being limited to the transmissive liquid crystal display element.
[0061]
(Embodiment 3)
FIG. 8 shows the structure of the projector according to the third embodiment of the present invention. The basic configuration of this projector is the same as that of the first embodiment, and is a dichroic prism type projector.
[0062]
White light emitted from the white light source 94 is separated into light of two colors, for example, blue and yellow (red + green) by the dichroic mirror 92. The B light passes through the total reflection mirror 96 and enters the liquid crystal display element 91B that displays a blue color signal component. On the other hand, the yellow light is further separated into R light and G light by the dichroic mirror 93, and enters the liquid crystal display elements 91R and 91G that display images based on the red and green color signals, respectively. The light incident on each of the liquid crystal display elements 91R, 91G, and 91B is modulated according to a signal corresponding to each pixel and is incident on the cross dichroic prism 90. The color light synthesized by the cross dichroic prism 90 is projected onto a screen (not shown) by the projection lens 95.
[0063]
In the first and second embodiments, the notch filter 1 or 70 is used as an independent wavelength selection element arranged at a free place. However, in this embodiment, the polarization direction of light is aligned in a certain direction. A method of using a notch filter on the optical path is shown.
[0064]
The transmissive liquid crystal display element 91 includes polarizing plates 101 and 102 on the incident / exit side of the liquid crystal cell 100 as shown in FIG. Therefore, the polarization directions of the light emitted from the liquid crystal display element 91 are all made uniform by these polarizing plates 101 or 102. That is, if it is on the optical path through which only light of a specific polarization direction passes, the polarization selection element (the polarizing plate 11 or 14 in FIG. 1) on the incident side of the notch filter 1 of Embodiment 1 is not necessary.
[0065]
In the present embodiment, the same color select 12 and 13 as in the first embodiment are used as the polarization regulating elements 97 and 98, which are attached to the output measurement of the cross dichroic prism 90, and further polarized as a polarization selection element on the output side. A plate 99 is placed. With this configuration, color purity is improved as in the first embodiment, and a brighter projection image than the projector according to the first embodiment can be displayed.
[0066]
Of course, it is not necessary to affix the polarization regulating elements 97 and 98 and the polarizing plate 99 to the cross dichroic prism 90, and they may be independently arranged on an appropriate optical path. Further, as shown in FIG. 10, it may be integrated with the liquid crystal display element 91.
[0067]
As in the first and second embodiments, the spectral characteristics of the notch filter 70 can be variously changed, and various display elements can be used without being limited to the transmissive liquid crystal display element.
[0068]
【The invention's effect】
According to the present invention, a combination of a polarization selection element and a plurality of polarization regulating elements having different wavelength bands to be operated is superior in performance to a notch filter formed using a conventional dielectric multilayer film. A wavelength selective element is obtained. Furthermore, by using the wavelength selection element of the present invention, for example, a projection display device having a higher color purity and capable of performing bright display is provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a wavelength selection element (notch filter) according to an embodiment of the present invention.
FIG. 2 is a graph showing spectral characteristics of a polarization regulating element used in an embodiment according to the present invention.
FIG. 3 is a graph showing spectral characteristics of other polarization regulating elements used in the embodiment according to the present invention.
FIG. 4 is a graph showing spectral characteristics of a wavelength selection element (notch filter) according to an embodiment of the present invention.
FIG. 5 is a schematic diagram showing a projector according to an embodiment of the invention.
FIG. 6 is a graph showing spectral characteristics of a reflective wavelength selection element (notch filter) according to an embodiment of the present invention.
FIG. 7 is a schematic diagram showing another projector according to the embodiment of the invention.
FIG. 8 is a schematic diagram showing another projector according to the embodiment of the invention.
FIG. 9 is a schematic view showing a transmissive liquid crystal display element used in an embodiment of the present invention.
FIG. 10 is a schematic view showing a transmissive liquid crystal display device including the wavelength selection device according to the embodiment of the present invention.
FIG. 11 is a schematic diagram of a conventional projector using a transmissive liquid crystal display element.
FIG. 12 is a schematic diagram of another conventional projector using a transmissive liquid crystal display element.
FIG. 13 is a schematic diagram of a conventional projector using a reflective liquid crystal display element.
FIG. 14A is a schematic diagram of another conventional projector using a reflective liquid crystal display element.
FIG. 14B is a schematic diagram of another conventional projector using a reflective liquid crystal display element.
FIG. 15 is a graph showing spectral emission characteristics of a metal halide lamp used in an embodiment according to the present invention.
FIG. 16 is a schematic diagram of a conventional wavelength selection element (notch filter).
[Explanation of symbols]
1 Notch filter
11, 14 Polarization selection element (polarizing plate or polarizing film)
12, 13 Polarization restricting element (color select)
60 Cross Dichroic Prism
61 Transmission type liquid crystal display element
62, 63 Dichroic mirror for color separation
64 White light source
65 Projection lens
71 Polarizing plate
72, 73 Polarization restricting element
74 Total reflection mirror

Claims (8)

A plurality of polarizations including at least a first polarization regulating element that changes a polarization state of light in the first wavelength range and a second polarization regulation element that changes a polarization state of light in a second wavelength range different from the first wavelength range. A regulating element;
A pair of polarization selection elements that are arranged to face each other via the plurality of polarization regulating elements, each selectively transmitting or reflecting light of a specific polarization direction;
Equipped with a,
Wherein the first wavelength region and the second at least partially mutually heavy Do that the wavelength selection element and the wavelength range. Before Symbol first and second polarization regulating element functions as a lambda / 2 plate with respect to each of the first wavelength range and the second wavelength band of light, the wavelength selection device according to claim 1.  3. The wavelength selection element according to claim 1, wherein each of the pair of polarization selection elements is disposed such that polarization axes of selectively transmitted or reflected light are substantially parallel to each other. A plurality of polarizations including at least a first polarization regulating element that changes a polarization state of light in the first wavelength range and a second polarization regulation element that changes a polarization state of light in a second wavelength range different from the first wavelength range A regulating element;
A reflection element and a polarization selection element that selectively transmits or reflects light in a specific polarization direction, disposed so as to face each other via the plurality of polarization regulating elements;
Equipped with a,
Wherein the first wavelength region and the second at least partially mutually heavy Do that the wavelength selection element and the wavelength range. Before Symbol first and second polarization regulating element functions as a lambda / 4 plate with respect to each of the first wavelength range and the second wavelength band of light, the wavelength selection device according to claim 4.  A display apparatus provided with the wavelength selection element in any one of Claim 1 to 5. A light source, a polarization selection element that selectively transmits or reflects light in a specific polarization direction of light emitted from the light source, a display element that modulates polarization selected by the polarization selection element, and the display element A projection optical element for projecting the modulated polarized light,
A plurality of polarization selection elements and a further polarization selection element are provided in this order on the light output side of the polarization selection element, and the polarization selection element changes the polarization state of light in the first wavelength range. When, at least seen including a second polarization regulating element for changing the polarization state of the first wavelength range and different from the second wavelength band of light,
The display device in which the first wavelength region and the second wavelength region are at least partially overlapped with each other . Before Symbol first and second polarization regulating element functions as a lambda / 2 plate with respect to each of the first wavelength range and the second wavelength band of light, the display device according to claim 7.

Images