JP2007212759A - Image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display apparatus capable of improving the contrast of an image displayed in black. <P>SOLUTION: The image display apparatus has: an image display element 10; and an illuminating optical system 100 that illuminates the image display element by using light from a light source. The illuminating system includes a filter 3 whose transmissivity relative to light having a wavelength of 670 nm or greater but 700 nm or shorter is <50%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display device such as a liquid crystal projector, and more particularly to an image display device having a filter (IR filter) that blocks infrared rays emitted from a light source such as a high-pressure mercury lamp.

  In recent years, there are many image display devices (liquid crystal projectors, etc.) that display images using image modulation elements (image display elements) that perform image modulation (image display) using polarized light, such as liquid crystal panels. Yes.

  In such an image display device, a polarizing plate is often used in order to improve the contrast of an image (Patent Document 1).

In Patent Document 1, a “BR polarizing plate” is arranged on a common optical path of B (blue) and R (red) light, thereby improving contrast.
JP 2001-154152 A (reference numeral 14 in FIG. 1)

  However, B and R are separated from each other in wavelength band, and there are few polarizing plates having good characteristics with respect to both B and R. In particular, there are many polarizing plates whose characteristics deteriorate with respect to the R wavelength, and even when black is displayed, it becomes reddish black and the contrast is lowered.

  Accordingly, an object of the present invention is to provide an image display device that can display more accurate black.

  An image display device according to an aspect of the present invention is an image display device including at least one image display element and an illumination optical system that illuminates the image display element using light from a light source, the illumination optical system The system is characterized by including an IR cut filter having a cut wavelength of 630 nm or more and 680 nm or less.

  An image display apparatus according to another aspect of the present invention is an image display apparatus having at least one image display element and an illumination optical system that illuminates the image display element using light from a light source, The illumination optical system includes a filter having a transmittance of less than 50% for light with a wavelength of 670 nm to 700 nm.

  An image display apparatus according to another aspect of the present invention is an image display apparatus having at least one image display element and an illumination optical system that illuminates the image display element using light from a light source, The illumination optical system includes a filter in which the transmittance of light at 635 nm is 30% or more higher than the transmittance of light at 680 nm.

  According to the present invention, it is possible to display a tighter black when displaying black, and to improve the contrast of an image.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a first embodiment of the present invention.

  A light beam emitted in all directions from the light source (light emitting portion of the lamp) 1 is emitted as substantially parallel light by the parabolic reflector 2. This parallel light beam enters an IR cut filter (infrared light cut filter) 3 and is divided into a plurality of partial light beams by the first lens array 4, and each of the partial light beams is collected. Each divided light beam is condensed near the second lens array 5, and each partial light beam forms a light source image (secondary light source image). The split luminous flux emitted from the second lens array 5 is collected by the condenser lens 6 and illuminates the reflective liquid crystal panel 10 in a superimposed manner. The IR cut filter cuts infrared light as used in Japanese Patent Application Laid-Open No. 2005-094272 (reference numeral 115 in FIG. 1), Japanese Patent Application Laid-Open No. 2005-134463 (reference numeral 115 in FIG. 1), and the like. It is a filter for. In this embodiment, it refers to a filter that shields (absorbs or reflects) light in a wavelength region of 700 nm to 800 nm in an amount of 50% or more (preferably 70% or more, more preferably 80% or more).

  The illumination optical system 100 is configured by the IR cut filter 3, the first lens array 4, the second lens array 5, the condenser lens 6, and the like. Here, the first lens array and the second lens array may be so-called fly-eye lenses in which minute lenses are two-dimensionally arranged, or may be so-called cylindrical lenses in which long thin lenses are one-dimensionally arranged.

  A dichroic mirror (first color separation member) 7 in FIG. 1 is a dichroic mirror that reflects blue (B) and red (R) color light and transmits green (G) color light, and 8 is polarized on a transparent substrate. It is the incident side polarizing plate G for G to which the element is stuck, and transmits only S-polarized light. Reference numeral 9 denotes a first polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  Reference numerals 10R, 10G, and 10B denote a reflective liquid crystal display element for red, a reflective liquid crystal display element for green, and a reflective liquid crystal display element for blue that reflect incident light and modulate the image, respectively. 11R, 11G, and 11B are a quarter wavelength plate for red, a quarter wavelength plate for green, and a quarter wavelength plate for blue, respectively. Reference numeral 12 denotes an incident-side polarizing plate having characteristics as shown in FIG. 2 in which a polarizing element is bonded to a transparent substrate, and mainly transmits S-polarized light. Reference numeral 13 denotes a first color selective phase difference plate that converts the polarization direction of the B color light by 90 degrees and does not convert the polarization direction of the R color light. Reference numeral 14 denotes a second polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface. Reference numeral 15 denotes a second color selective phase difference plate that converts the polarization direction of the R color light by 90 degrees and does not convert the polarization direction of the B color light.

  Reference numeral 16 denotes an output-side polarizing plate (polarizing element) that transmits only S-polarized light. Reference numeral 17 denotes a third polarization beam splitter (color combining means) that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  The above-described dichroic mirror 7 and the third polarization beam splitter 17 constitute a color separation / synthesis optical system 200.

  Reference numeral 18 denotes a projection lens optical system, and an image display optical system is constituted by the illumination optical system, the color separation / synthesis optical system, and the projection lens optical system (projection optical system).

  Next, the optical action after passing through the illumination optical system will be described. First, the G optical path will be described.

  The G color light transmitted through the dichroic mirror 7 enters the incident side polarizing plate G8. The G color light is emitted from the incident-side polarizing plate G8, then enters the first polarizing beam splitter 9 as S-polarized light, and is reflected by the polarization separation surface, and is reflected to the G reflective liquid crystal display element 10G. It reaches. In the reflective liquid crystal display element 10G for G, the G color light is image-modulated and reflected. Of the image-modulated G reflected light, the S-polarized light component is reflected again by the polarization separation surface of the first polarization beam splitter 9, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the image-modulated G reflected light passes through the polarization separation surface of the first polarization beam splitter 9 and travels to the third polarization beam splitter 17 as projection light. At this time, in a state in which all the polarization components are converted to S-polarized light (a state in which black is displayed), ¼ provided between the first polarizing beam splitter 9 and the reflective liquid crystal display element 10G for G. The slow axis of the wave plate 11G is adjusted in a predetermined direction. By this adjustment, it is possible to suppress the influence of the polarization state disturbance generated in the first polarizing beam splitter 9 and the reflective liquid crystal display element 10G for G, and to suppress a decrease in contrast. The G color light emitted from the first polarization beam splitter 9 enters the third polarization beam splitter 17 as P-polarized light, passes through the polarization separation surface of the third polarization beam splitter 17, and then enters the projection lens 18. And so on.

  On the other hand, the R and B color lights reflected by the dichroic mirror 7 enter the incident side polarizing plate 12. The R and B color lights are emitted from the incident-side polarizing plate 12 and then enter the first color-selective retardation plate 13. The first color-selective retardation plate 13 has an action of rotating only the B color light by 90 degrees in the polarization direction, so that the B color light becomes P-polarized light, and the R color light becomes S-polarized light. The light enters the beam splitter 14. The R color light incident on the second polarization beam splitter 14 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 14 and reaches the R reflective liquid crystal display element 10R. Further, the B light incident on the second polarization beam splitter 14 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 14 and reaches the B reflective liquid crystal display element 10B.

  The R color light incident on the R reflective liquid crystal display element 10R is image-modulated and reflected. The S-polarized light component of the image-modulated R reflected light is reflected again by the polarization separation surface of the second polarization beam splitter 14, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the R light reflected by the image modulation passes through the polarization separation surface of the second polarization beam splitter 14 and travels to the second color selective phase plate 15 as projection light.

  The B color light incident on the B reflective liquid crystal display element 10B is image-modulated and reflected. The P-polarized component of the image-modulated B reflected light is again transmitted through the polarization separation surface of the second polarization beam splitter 14 and returned to the light source side, and is removed from the projection light. On the other hand, the S-polarized component of the image-modulated B reflected light is reflected by the polarization separation surface of the second polarizing beam splitter 14 and travels toward the second color selective phase plate 15 as projection light.

  At this time, by adjusting the slow axes of the quarter-wave plates 11R and 11B provided between the second polarizing beam splitter 14 and the reflective liquid crystal display elements 10R and 10B for R and B, G As in the case of, the black display of R and B can be adjusted.

  In this way, the R image light and the B image light are combined into one light beam. The R image light emitted from the second polarization beam splitter 14 is rotated by 90 degrees in the polarization direction by the second color selective phase plate 15 to become an S polarization component, and is further analyzed by the exit side polarization plate 16. Then, the light enters the third polarization beam splitter 17. Further, the B color light passes through the second color selective phase plate 15 as it is as S-polarized light, and is further analyzed by the output side polarizing plate 16 and incident on the third polarizing beam splitter 17. The R- and B-projected lights are analyzed by the exit-side polarizing plate 16 so that the R and B reflective liquid crystal display elements 10R and 10B and the quarter-wave plate are reflected by the second polarizing beam splitter 14. The ineffective component generated by passing through 11R and 11B is cut light.

  The R and B projection light incident on the third polarization beam splitter 17 reflects the polarization separation surface of the third polarization beam splitter 17 and is combined with the G color light reflected on the polarization separation surface described above. To the projection lens 18.

  Then, the combined R, G, B projection light is enlarged and projected onto a projection surface such as a screen by the projection lens 18.

  Since the optical path described above is for the case where the reflective liquid crystal display element displays white, the optical path for the case where the reflective liquid crystal display element displays black will be described below.

  First, the G optical path will be described.

  S-polarized light of G color light transmitted through the dichroic mirror 7 enters the incident-side polarizing plate 8, and then enters the first polarizing beam splitter 9 and is reflected by the polarization separation surface, and is a reflective liquid crystal display for G. It reaches the element 10G. However, since the reflective liquid crystal display element 10G displays black, the G color light is reflected without being image-modulated. Accordingly, since the G color light remains S-polarized light even after being reflected by the reflective liquid crystal display element 10G, it is reflected again by the polarization separation surface of the first polarization beam splitter 9 and transmitted through the incident-side polarizing plate 8. Then, it is returned to the light source side and removed from the projection light.

  Next, the R and B optical paths will be described.

  S-polarized light of R and B color light reflected by the dichroic mirror 7 enters the incident-side polarizing plate 12. The R and B lights are emitted from the incident-side polarizing plate 12 and then enter the first color-selective retardation plate 13. The first color-selective retardation plate 13 has an action of rotating only the B color light by 90 degrees in the polarization direction, so that the B light is P-polarized light and the R light is S-polarized light. The light enters the beam splitter 14. The R color light incident on the second polarization beam splitter 14 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 14 and reaches the R reflective liquid crystal display element 10R. Further, the B light incident on the second polarization beam splitter 14 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 14 and reaches the B reflective liquid crystal display element 10B. Here, since the R reflective liquid crystal display element 10R displays black, the R color light incident on the R reflective liquid crystal display element 10R is reflected without being image-modulated. Accordingly, even after being reflected by the reflective liquid crystal display element 10R for R, the R color light remains as S-polarized light, and is reflected again by the polarization separation surface of the second polarization beam splitter 14, and is incident side polarizing plate. 12 is returned to the light source side and removed from the projection light, so that black display is obtained. On the other hand, the B color light incident on the B reflective liquid crystal display element 10B is reflected without being image-modulated because the B reflective liquid crystal display element 10B displays black. Thus, during black display, the B color light is again incident on the polarization separation surface of the second polarization beam splitter 14 as P-polarized light. Since the B light is P-polarized light, it is transmitted through the second polarizing beam splitter 14, converted to S-polarized light by the first color-selective phase difference plate 13, and transmitted through the incident-side polarizing plate 12 to the light source side. By being returned to (2), it is removed from the projection light (shielded against the projection optical system).

  The above is the optical configuration in the projection type image display apparatus using the reflective liquid crystal display element (reflective liquid crystal panel).

  In the explanation of the white and black display performed here, the transmission through the polarizing beam splitter is 0 for the S-polarized light with respect to the P-polarized light 100, 0 for the reflection with respect to the S-polarized light 100, This is the case in an ideal state where the 100% polarization direction is rotated 90 degrees in the wavelength region. Actually, for example, the reflection at the modified beam splitter has a value such as 1 for the S-polarized light and 1 for the P-polarized light, and the illuminance at the time of black display does not become 0. There is an illuminance of about 1 or less.

  Here, the spectral characteristic of the IR cut filter 3 is shown in FIG. 3, and the spectral characteristic of the incident side polarizing plate 12 is shown in FIG. Since the incident side polarizing plate 12 allows R and B light to pass therethrough, it is conceivable to use a broadband polarizing plate corresponding to the entire wavelength range of visible light, but the transmittance of polarized light parallel to the transmission axis is 80%. However, the amount of light in the white display of R and B becomes low, resulting in a problem that the color becomes greenish white. Therefore, in this embodiment, the incident side polarizing plate 12 is a polarizing plate having a good transmittance of polarized light parallel to the transmission axis and having the characteristics of FIG. 2 mainly made in the G wavelength band. This polarizing plate has good transmittance of polarized light parallel to the transmission axis over the entire wavelength range of visible light. However, at a long wavelength of 630 nm or more, the transmittance of polarized light perpendicular to the transmission axis is increased and the light detection performance is not good. For this reason, in addition to the S-polarized light originally transmitted by the polarizing plate, P-polarized light having a wavelength of 630 nm or more is also transmitted. The P-polarized light of 630 nm or more is transmitted through the first color-selective retardation plate 13 as P-polarized light, passes through the polarization separation surface of the second polarizing beam splitter 14, and is a B reflective liquid crystal display element. 10B. The reflective liquid crystal display element 10B for B should reflect the P-polarized light without changing the polarization direction during black display, but the quarter-wave plate 11B is optimally adjusted to the B color light. Therefore, light of 630 nm or more is emitted in a state other than P-polarized light. As a result, despite the black display, light having a wavelength of 630 nm or more is projected as a leakage light onto a projection surface such as a screen, and a reddish black is displayed. If an IR cut filter having a spectral characteristic as shown in FIG. 2 is also used to solve this problem, the long wavelength side light does not exist in the projection light, so that black does not become reddish.

  When a wavelength at which the transmittance is 50% is referred to as a cut wavelength, the cut wavelength is set to 660 nm in FIG. If the cut wavelength is less than 680 nm, a certain effect can be obtained. More preferably, the cut wavelength is less than 670 nm, and further longer than 630 nm. Here, setting the cut wavelength to a wavelength shorter than 630 nm is not preferable because the color purity of the R light is reduced and the white balance is lost due to the decrease in the amount of R light.

  In other words, this IR cut filter preferably blocks 50% (more preferably 70%, more preferably 80%) or more of light in the wavelength region (visible light region) from 670 nm to 700 nm. In other words, the transmittance of the IR cut filter for 635 nm light is 30% or more (preferably 50% or more) higher than the transmittance for 680 nm light. Furthermore, the transmittance for 635 nm light is 30% or more (preferably 50% or more) higher than the transmittance for 700 nm light, and more specifically, 30% or more (preferably 50% or more) than the transmittance for 720 nm light. What is necessary is just to comprise so that it may become high.

  In the present embodiment, the IR cut filter 3 is disposed between the light source and the first lens array 4, and light from the light source enters the IR cut filter without passing through other optical elements. It has a configuration. The arrangement position of the IR cut filter is not limited to this, and it may be arranged in another place as long as it is arranged in the illumination optical system. In other words, if the IR cut filter is arranged before white light emitted from the light source is color-separated, that is, between the light source and the color separation optical system, a certain degree of effect can be obtained. However, an IR cut filter is disposed on the light source side of the polarization conversion element disposed in the illumination optical system 100, more preferably on the light source side of the second lens array, and more preferably on the light source side of the first lens array. It is still more preferable.

  In some projectors, a polarization conversion element (polarization beam splitter array) may be disposed in the vicinity of the lens array in order to increase the light utilization efficiency. Although not shown in the present embodiment, it is generally arranged on the condenser lens 6 side of the second lens array 5 and the polarization direction is aligned by this polarization conversion element. On the other hand, the ideal state of P polarization 0 is not achieved. Further, since a dichroic mirror or the like is interposed in the middle of the optical path, there are actually about 5 to 10 P-polarized light with respect to the S-polarized light 100. Therefore, the same effect can be obtained by arranging the IR cut filter of the present invention.

  The color separation / synthesis optical system is not limited to the configuration of the first embodiment of the present invention. FIG. 4 shows an embodiment using a color separation / synthesis optical system having another configuration as a second embodiment of the present invention. Since the illumination optical system is the same as that of the first embodiment, description thereof is omitted.

  A light beam emitted from the light source (light emitting portion of the lamp) 1 in all directions is emitted as substantially parallel light by the paraboloid reflector 2 and guided to the reflective liquid crystal display element 39 by the illumination optical system 100.

  A dichroic mirror 37 in FIG. 4 is a dichroic mirror that reflects blue (B) and red (R) color light and transmits green (G) color light. Reference numeral 38 denotes a first polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  Reference numerals 39R, 39G, and 39B denote a reflective liquid crystal display element for red, a reflective liquid crystal display element for green, and a reflective liquid crystal display element for blue that reflect incident light and modulate the image, respectively. 40R, 40G, and 40B are a quarter wavelength plate for red, a quarter wavelength plate for green, and a quarter wavelength plate for blue, respectively. Reference numeral 44 denotes a G-use exit side polarizing plate G that transmits S-polarized light.

  Reference numeral 41 denotes an incident-side polarizing plate having a characteristic as shown in FIG. 5 in which a polarizing element is bonded to a transparent substrate, and mainly transmits P-polarized light. Reference numeral 42 denotes a color selective phase difference plate A that converts the polarization direction of the R light by 90 degrees and does not convert the polarization direction of the B light. Reference numeral 43 denotes a second polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  Reference numeral 45 denotes an exit side polarizing plate for B, which has characteristics as shown in FIG. The B color light transmits only S-polarized light, and the red color light transmits regardless of the polarization direction. The combining prism 46 also has the characteristics as shown in FIG. 7, and is a prism having the characteristics of a polarization beam splitter that transmits dichroic mirrors for B and G color light, transmits P-polarized light for R color light, and reflects S-polarized light.

  A color separation / synthesis optical system 300 is configured by the synthesis prism 46 from the dichroic mirror 37 described above.

  Reference numeral 47 denotes a projection lens optical system, and the illumination optical system, color separation / synthesis optical system, and projection lens optical system constitute an image display optical system.

  Next, the optical action after passing through the illumination optical system will be described. First, the G optical path will be described.

  The G color light transmitted through the dichroic mirror 37 is incident on the first polarization beam splitter 38, and P-polarized light is transmitted through the polarization separation surface to reach the G reflective liquid crystal display element 39G. In the reflective liquid crystal display element 39G for G, the G light is image-modulated and reflected. The P-polarized component of the image-modulated G reflected light is transmitted again through the polarization separation surface of the first polarization beam splitter 9, returned to the light source side, and removed from the projection light. On the other hand, the S-polarized light component of the image-modulated G reflected light is reflected by the polarization separation surface of the first polarizing beam splitter 9 and is transmitted through the exit-side polarizing plate G44 that transmits the S-polarized light, and the combined prism is used as projection light. Head to 46. At this time, in a state in which all the polarization components are converted to P-polarized light (a state in which black is displayed), ¼ provided between the first polarizing beam splitter 38 and the reflective liquid crystal display element 39G for G. The slow axis of the wave plate 40G is adjusted in a predetermined direction. By this adjustment, the influence of the disturbance of the polarization state generated in the first polarizing beam splitter 38 and the reflective liquid crystal display element 39G for G can be suppressed, and the contrast can be improved. The G color light emitted from the first polarizing beam splitter 38 is transmitted through the output-side polarizing plate G44, reflected by the combining prism 46, and reaches the projection lens 47.

  On the other hand, the R and B color lights reflected by the dichroic mirror 37 are incident on an incident-side polarizing plate 41 having the characteristics shown in FIG. 5 and mainly transmitting P-polarized light. The R and B lights exit from the incident-side polarizing plate 41 and then enter the color selective phase difference plate A42. The color-selective phase difference plate A42 has an action of rotating only the R color light by 90 degrees in the polarization direction, whereby the R color light is converted to S-polarized light, and the B color light is converted to P-polarized light. Is incident on. The R color light incident on the second polarization beam splitter 43 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 43 and reaches the R reflective liquid crystal display element 39R. The B color light incident on the second polarization beam splitter 43 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 43 and reaches the B-use reflective liquid crystal display element 39B.

  The R color light incident on the reflective liquid crystal display element 39R for R is image-modulated and reflected. The S-polarized light component of the image-modulated R reflected light is reflected again by the polarization separation surface of the second polarization beam splitter 43, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the image-modulated reflected R light passes through the polarization separation surface of the second polarization beam splitter 43 and travels toward the exit-side polarizing plate 45 as projection light.

  The B color light incident on the B reflective liquid crystal display element 39B is image-modulated and reflected. The P-polarized component of the image-modulated B reflected light is again transmitted through the polarization separation surface of the second polarization beam splitter 43, returned to the light source side, and removed from the projection light. On the other hand, the S-polarized light component of the image-modulated B reflected light is reflected by the polarization separation surface of the second polarization beam splitter 43 and travels toward the exit-side polarizing plate 45 as projection light.

  At this time, by adjusting the slow axes of the quarter-wave plates 40R and 40B provided between the second polarizing beam splitter 43 and the reflective liquid crystal display elements 39R and 39B for R and B, G As in the case of, the black display of R and B can be adjusted.

  In this way, the R and B color lights that are combined into a single light beam and emitted from the second polarization beam splitter 43 are P-polarized light for the R color light and S-polarized light for the B color light, and are incident on the output side polarizing plate 45 and the combining prism 46. To do.

  The R and B projection light passes through the combining prism 46 and is combined with the G color light to reach the projection lens 47.

  The combined R, G, B projection light is enlarged and projected onto a projection surface such as a screen by the projection lens 47.

  Since the optical path described above is for the case where the reflective liquid crystal display element displays white, the optical path for the case where the reflective liquid crystal display element displays black will be described below.

  First, the G optical path will be described.

  The P-polarized light of the G color light that has passed through the dichroic mirror 37 enters the first polarization beam splitter 38, is transmitted through the polarization separation surface, and reaches the reflective liquid crystal display element 39G for G. However, since the reflective liquid crystal display element 39G displays black, the G color light is reflected without being image-modulated. Accordingly, since the G color light remains P-polarized light even after being reflected by the reflective liquid crystal display element 39G, it is transmitted again through the polarization separation surface of the first polarization beam splitter 38, returned to the light source side, and projected. Removed from light.

  Next, the R and B optical paths will be described.

  The R and B color lights reflected by the dichroic mirror 37 are incident on the incident-side polarizing plate 41 that mainly transmits P-polarized light with the characteristics shown in FIG. The R and B color lights are emitted from the incident-side polarizing plate 41 and then enter the color selective phase difference plate A42. The color-selective phase difference plate A42 has an action of rotating the polarization direction of only the R color light by 90 degrees, whereby the R color light is converted to S-polarized light, and the B color light is converted to S-polarized light. Is incident on. The R color light incident on the second polarization beam splitter 43 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 43 and reaches the R reflective liquid crystal display element 39R. The B color light incident on the second polarization beam splitter 43 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 43 and reaches the B-use reflective liquid crystal display element 39B. Here, since the R reflective liquid crystal display element 39R displays black, the R color light incident on the R reflective liquid crystal display element 39R is reflected without being image-modulated. Accordingly, even after being reflected by the reflective liquid crystal display element 39R for R, the R color light remains as S-polarized light, and is removed from the projection light by returning to the light source side again (with respect to the projection optical system). Black). On the other hand, the B color light incident on the B reflective liquid crystal display element 39B is reflected without being image-modulated because the B reflective liquid crystal display element 39B displays black. Therefore, even after being reflected by the reflective liquid crystal display element 39B for B, the color light of B remains as P-polarized light, so that it again passes through the polarization separation surface of the second polarization beam splitter 43, and enters the incident side polarizing plate. 41 is transmitted back to the light source side and removed from the projection light.

  The above is the optical configuration in the projection type image display apparatus using the reflective liquid crystal display element (reflective liquid crystal panel).

  Here, the spectral characteristic of the IR cut filter 3 is shown in FIG. 3, and the spectral characteristic of the incident side polarizing plate 41 is shown in FIG. As in the first embodiment, the incident side polarizing plate 41 uses a polarizing plate having a good transmittance of polarized light parallel to the transmission axis and having the characteristics shown in FIG. In this embodiment, as in the first embodiment, the IR cut filter having the spectral characteristics shown in FIG. 3 is also used to cut light on the long wavelength side so that the black does not become reddish.

  In both the first and second embodiments, the IR cut filter is disposed immediately after the reflector 2, but the present invention is not limited to this. Since it is sufficient that the light on the long wavelength side is not projected, the same effect can be obtained even if it is disposed in the color separation / synthesis optical system and the projection lens optical system without being limited to the illumination optical system.

  The color separation / combination optical system is not limited to the configuration of the first and second embodiments, and the same as long as there is a polarizing plate on which the light beams of both R and B are incident on the light source side from the image display element. An effect is obtained.

  The following can be said about this embodiment described above. The first image display apparatus of the present embodiment is an image display apparatus having at least one image display element and an illumination optical system that illuminates the image display element with light from a light source, and the illumination optical system includes: A filter having a cut wavelength of not less than 630 nm and not more than 680 nm is included. In the second image display device of the present embodiment, the illumination optical system includes a filter having a transmittance of less than 50% for light having a wavelength of 670 nm to 700 nm. In the third image display apparatus according to the present embodiment, the illumination optical system includes a filter in which the transmittance of light at 635 nm is 30% or more higher than the transmittance of light at 680 nm. Here, it is desirable that the filter is an IR cut filter that also shields infrared light.

  The fourth image display apparatus according to the present embodiment includes blue, green, and red image display elements that modulate blue, green, and red light in accordance with an image signal, and the three image display elements using light from a light source. An illumination optical system for illuminating and a projection optical system for projecting image light from the three image display elements are included. Further, the light from the illumination optical system is decomposed into blue light, green light, and red light and guided to the three image display elements, and the image light from the three image display elements is synthesized to the projection optical system. And a color separation / synthesis system for guiding. In addition, it includes a filter having a cut wavelength of 630 nm or more and 680 nm or less. The fifth image display device of the present embodiment includes a filter that has a transmittance of less than 50% for light having a wavelength of 670 nm to 700 nm. The sixth image display apparatus of the present embodiment includes a filter in which the transmittance of light at 635 nm is 30% or more higher than the transmittance of light at 680 nm. Here, the color separation / synthesis system includes the following five optical elements. The first optical element is a first color separation member that divides the light from the illumination optical system into a combined luminous flux of the blue light and the red light and the green light, and is a second optical element The element is a first polarization beam splitter that guides the green light to the green image display element. The third optical element is disposed in an optical path of the combined light beam of the blue light and the red light, rotates a polarization plane of one of the blue light and the red light by 90 degrees, This is a wavelength-selective phase difference plate that does not change the plane of polarization. The fourth optical element guides the blue light to the blue image display element and the red light to the red image display element out of the combined light flux through the wavelength selective phase difference plate. It is a two-polarization beam splitter. The fifth optical element is a color combining element that combines the green light from the first polarizing beam splitter and the red light and blue light from the second polarizing beam splitter.

First embodiment of the present invention Characteristics of incident side polarizing plate 12 Characteristics of IR cut filter 3 Second embodiment of the present invention Characteristics of incident-side polarizing plate 41 Characteristics of exit side polarizing plate 45 Characteristics of composite prism 46

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Reflector 3 IR cut filter 4 1st lens array 5 2nd lens array 6 Condenser lens 7, 37 Dichroic mirror 8 Incident side polarizing plate G
9, 38 First polarizing beam splitter 10, 39 Image display element 11, 40 1/4 wavelength plate 12, 41 Incident side polarizing plate 13, 15 Color selective phase difference plate 42 Color selective phase difference plate A
14, 43 Second polarization beam splitter
16 Output-side polarizing plate 17 Third polarization beam splitter 44 Output-side polarizing plate G
45 Output-side polarizing plate 46 Synthetic prism 18, 47 Projection lens optical system 100 Illumination optical system 200, 300 Color separation / synthesis optical system

Claims (11)

At least one image display element;
An image display device having an illumination optical system that illuminates the image display element using light from a light source,
The illumination optical system is
An image display device comprising an IR cut filter having a cut wavelength of 630 nm to 680 nm. At least one image display element;
An image display device having an illumination optical system that illuminates the image display element using light from a light source,
The image display apparatus, wherein the illumination optical system includes a filter having a transmittance of less than 50% for light having a wavelength of 670 nm to 700 nm. At least one image display element;
An image display device having an illumination optical system that illuminates the image display element using light from a light source,
The image display apparatus, wherein the illumination optical system includes a filter such that the transmittance of light at 635 nm is 30% or more higher than the transmittance of light at 680 nm. The illumination optical system includes:
A lens array that divides the light through the filter into a plurality of partial luminous fluxes;
A polarization conversion element that aligns the polarization direction of each of the plurality of partial light beams;
A condenser lens that superimposes a plurality of partial light beams emitted from the polarization conversion element on the at least one image display element;
The image display device according to claim 1, further comprising: The at least one image display element includes three image display elements corresponding to red, green, and blue,
The illumination optical system includes a color separation optical system that separates light through the condenser lens into light of three colors corresponding to red, green, and blue, and guides each color light to the three image display elements,
The image display device according to claim 4. An image display element for blue that modulates blue light according to an image signal;
An image display element for green that modulates green light according to an image signal;
An image display element for red that modulates red light according to an image signal;
An illumination optical system that illuminates the three image display elements with light from a light source;
A projection optical system for projecting image light from the three image display elements;
A color that decomposes light from the illumination optical system into blue light, green light, and red light, guides the light to the three image display elements, and combines the image light from the three image display elements to guide the projection optical system A decomposition and synthesis system,
Here, the image display apparatus characterized by including the filter whose cut wavelength is 630 nm or more and 680 nm or less. An image display element for blue that modulates blue light according to an image signal;
An image display element for green that modulates green light according to an image signal;
An image display element for red that modulates red light according to an image signal;
An illumination optical system that illuminates the three image display elements with light from a light source;
A projection optical system for projecting image light from the three image display elements;
A color that decomposes light from the illumination optical system into blue light, green light, and red light, guides the light to the three image display elements, and combines the image light from the three image display elements to guide the projection optical system A decomposition and synthesis system,
Here, an image display device including a filter having a transmittance of less than 50% with respect to light having a wavelength of 670 nm to 700 nm. An image display element for blue that modulates blue light according to an image signal;
An image display element for green that modulates green light according to an image signal;
An image display element for red that modulates red light according to an image signal;
An illumination optical system that illuminates the three image display elements with light from a light source;
A projection optical system for projecting image light from the three image display elements;
A color that decomposes light from the illumination optical system into blue light, green light, and red light, guides the light to the three image display elements, and combines the image light from the three image display elements to guide the projection optical system A decomposition and synthesis system,
Here, the image display apparatus includes a filter in which the transmittance of light of 635 nm is 30% or more higher than the transmittance of light of 680 nm.   The image display device according to claim 6, wherein the filter is disposed inside the illumination optical system. The color separation / synthesis system is:
A first color separation member that divides light from the illumination optical system into a combined luminous flux of the blue light and the red light and the green light;
A first polarizing beam splitter for guiding the green light to the green image display element;
Wavelength selection that is arranged in the optical path of the combined light beam of the blue light and the red light, rotates the polarization plane of one of the blue light and red light by 90 degrees, and does not change the other polarization plane A phase difference plate,
A second polarization beam splitter that guides the blue light to the blue image display element and the red light to the red image display element of the combined light flux through the wavelength selective phase difference plate;
A color combining element that combines green light from the first polarizing beam splitter and red light and blue light from the second polarizing beam splitter;
The image display device according to claim 6, comprising:   The image display device according to claim 10, further comprising a polarizing plate between the first color separation member and the second polarizing beam splitter.

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