JP2007212773A - Optical system having optical filter, and image projection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a projected image showing high contrast and favorable color reproducibility and white balance. <P>SOLUTION: The optical system comprises color separation systems 7, 14, 15 to separate the light from a light source 1 into light of three colors and an optical filter 24 disposed in the light source side than the color separation system. The optical filter has a transmittance of higher than 80% for at least one color light in the three colors and transmittances of 40% to 80% for light in other colors. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical system used in an image projection apparatus that projects an image formed by a light modulation element such as a liquid crystal panel, and more particularly to an optical system having an optical filter between a light source and a color separation system.

  Each color of red (R), green (G), and blue (B) in a projected image by a liquid crystal projector is a color separation element such as a dichroic mirror or a trimming filter disposed in an optical path that guides light from a white light source to a liquid crystal panel. Determined by That is, white light is decomposed into RGB three-color light according to the setting of the wavelength range reflected or transmitted by the dichroic mirror or the trimming filter, thereby determining the color of the monochromatic light.

In this way, each single color is basically determined by setting the characteristics of the color separation element. However, in Patent Document 1, a dichroic filter is disposed in the optical path from the light source to the color separation element, and the color is determined by inserting and removing the filter. A projector capable of changing purity and color balance is disclosed. In the projector disclosed in Patent Document 1, by inserting a dichroic filter, light in a wavelength range between blue and green and light in a wavelength range between green and blue are cut, thereby increasing the color purity of green. Can do.
JP-A-7-72450 (paragraph 0019, FIG. 2, FIG. 4 etc.)

  However, in the projector disclosed in Patent Document 1, when a dichroic filter is inserted to widen a color reproduction range, light in a predetermined wavelength range is removed from a spectrum distribution in a state where the filter is not inserted. It will be. As a result, there is a problem that a white color balance (white balance) obtained by synthesizing RGB light is lost.

  Further, when a light source having strong luminance near 580 nm, such as a high-pressure mercury lamp, is used, the light amount in the wavelength region between green and red is larger than the light amount in the wavelength region between blue and green. For this reason, when the light in the wavelength range between blue and green and the light in the wavelength range between green and red are cut by the dichroic filter described above, the wavelength range between red and green (yellow, orange) is displayed during white display. A white color shifted in the direction of blue, which is a complementary color, is displayed.

  In order to correct such white shift, white balance is electrically adjusted by limiting the output levels of the green and blue liquid crystal panels. However, since this adjustment is an adjustment that changes the brightness of the image from a bright state to a dark state, the brightness at the time of white display is reduced without changing the brightness at the time of black display. For this reason, the contrast, which is the ratio of the brightness when displaying all white and the brightness when displaying all black, is reduced.

  Further, since the driving range of the liquid crystal is greatly limited by the electrical adjustment as described above, there is a problem that the capability of the liquid crystal panel cannot be effectively utilized.

  An object of the present invention is to provide an optical system capable of obtaining an image with high contrast and good color reproducibility and white balance.

  An optical system according to one aspect of the present invention includes a color separation system that separates light from a light source into first, second, and third color lights, and an optical filter that is disposed closer to the light source than the color separation system. Have. The optical filter is characterized in that the transmittance for one or two of the first to third color lights is higher than 80%, and the transmittance for the other color lights is 40% or more and 80% or less. To do.

  An image projection optical system and an image projection apparatus that project an image using the optical system constitute another aspect of the present invention. Furthermore, an image display system including the image projection apparatus and an image supply apparatus that supplies image information to the image projection apparatus also constitutes another aspect of the present invention.

  According to the present invention, it is possible to obtain an image with good color reproducibility and white balance while being an image with high contrast.

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

  FIG. 1 shows an optical configuration of a liquid crystal projector that is Embodiment 1 of the present invention. Reference numeral 1 denotes an arc tube such as a high-pressure mercury lamp, and 2 denotes a reflector. The arc tube 1 and the reflector 2 constitute a light source lamp.

  Reference numerals 3 and 4 denote first and second lens arrays each composed of a plurality of lens cells, which divides a light beam from the light source lamp 1 into a plurality of light beams and forms a secondary light source image in the vicinity of the second lens array 4. To do. Reference numeral 23 denotes a UVIR cut filter disposed between the first and second lens arrays 3 and 4, which removes light components in the ultraviolet region and the infrared region from the light from the light source lamp 1.

  Further, in this embodiment, a light amount correction filter 24 that is an optical filter is put in and out of a region between the first and second lens arrays 3 and 4 (between the UVIR cut filter 23 and the second lens array 4). It is provided as possible. This loading / unloading is performed using the driving force of an actuator (not shown) in accordance with the user's switch operation (display mode switching switch operation such as movie mode or color reproducibility priority mode). Here, in this embodiment, the UVIR cut filter 23 and the light amount correction filter 24 are both disposed between the first and second lens arrays 3 and 4, but the present invention is not limited to this. Both may be arranged between the reflector 2 and the first lens array 3, or may be arranged between the second lens array and a polarization conversion element 5 described later. However, it is desirable that the UVIR cut filter (a filter that cuts at least one of UV and IR) 23 is disposed on the light source side with respect to the light amount correction filter 24.

  A polarization conversion element 5 converts non-polarized light from the second lens array 4 into linearly polarized light having a predetermined polarization direction. A condenser lens 6 condenses a plurality of split light beams from the polarization conversion element 5 so as to be superimposed on a liquid crystal panel described later. The illumination system is configured as described above.

  Reference numeral 7 denotes a dichroic mirror that transmits G light out of the light from the condenser lens 6 and reflects R light and B light. A trimming filter 25 is disposed in the optical path of the R and B light, and is a filter for removing a yellow light component from G. The wavelength band of B light is, for example, 425 to 495 nm, and the wavelength band of G light is, for example, 500 to 585 nm. The wavelength band of R light is, for example, 590 to 650 nm.

  Reference numerals 8, 9, and 10 denote reflective liquid crystal panels as light modulation elements or image forming elements for forming original images for G, R, and B, respectively. An image supply device 200 such as a personal computer, a DVD player, or a TV tuner is connected to the liquid crystal driving circuit 100 of the projector. The liquid crystal drive circuit 100 drives each reflective liquid crystal panel based on image (video) information input from the image supply device 200, and forms an original image for each color. Thereby, the light incident on each reflective liquid crystal panel is reflected and modulated (image modulation) according to the original image. Reference numerals 11, 12, and 13 denote phase plates for G, R, and B, respectively.

  Reference numeral 14 denotes a first polarizing beam splitter, and 15 denotes a second polarizing beam splitter. Reference numeral 16 denotes a first polarizing plate, and 17 denotes a second polarizing plate. A color selective phase plate 18 converts the polarization direction of the R light by 90 degrees and does not convert the polarization direction of the B light. Reference numeral 19 denotes a third polarizing plate, and 20 denotes a fourth polarizing plate. A color combining prism 21 reflects G projection light and transmits B and R projection light. The dichroic mirror 7 and the color synthesis prism 21 constitute a color separation / synthesis system.

  In this color separation / synthesis system, the G light transmitted through the dichroic mirror 7 passes through the first polarizing plate 16 and enters the first polarizing beam splitter 14. Then, the light passes through the polarization separation surface of the first polarization beam splitter 14, passes through the phase plate 11, and reaches the G reflective liquid crystal panel 8. The G light reflected and image-modulated by the reflective liquid crystal panel 8 passes through the phase plate 11, is reflected by the polarization separation surface of the first polarizing beam splitter 14, and is analyzed by the third polarizing plate 19 to be colored. The light enters the combining prism 21.

  The R and B lights reflected by the dichroic mirror 7 pass through the trimming filter 25 and the second polarizing plate 17, and then the polarization direction of only the B light is rotated by 90 ° by the color-selective phase plate 18 to obtain the second polarized light. The light enters the beam splitter 15. The R light is reflected by the polarization separation surface of the second polarization beam splitter 15, passes through the phase plate 12, and reaches the R reflective liquid crystal panel 9. The R light reflected and image-modulated by the reflective liquid crystal panel 9 passes through the phase plate 12, then passes through the polarization separation surface of the second polarizing beam splitter 15, and is analyzed by the fourth polarizing plate 20 to be colored. The light enters the combining prism 21.

  The B light passes through the polarization separation surface of the second polarization beam splitter 15, passes through the phase plate 13, and reaches the B-use reflective liquid crystal panel 10. The B light reflected and image-modulated by the reflective liquid crystal panel 10 passes through the phase plate 13, is reflected by the polarization separation surface of the second polarizing beam splitter 15, and is analyzed by the fourth polarizing plate 20 to be colored. The light enters the combining prism 21.

  Reference numeral 22 denotes a projection lens. The G light incident on the color synthesis prism 21 is reflected by the polarization separation surface of the color synthesis prism 21 and travels toward the projection lens 22. Further, the R and B lights incident on the color synthesis prism 21 pass through the polarization separation surface of the color synthesis prism 21 and travel toward the projection lens 22.

  The R, G, B projection light (color image) synthesized by the color synthesis prism 21 is projected onto a projection surface such as a screen (not shown) by the projection lens 22.

  Here, FIG. 2 shows the characteristics of the UVIR cut filter 23. The UVIR cut filter 23 cuts light having a wavelength of 425 nm or less and light having a wavelength of 680 nm or more out of the light emitted from the light source lamp 1. Here, the cut wavelength (wavelength at which the transmittance is 50%) of the UVIR cut filter 23 may be 415 nm (preferably 420 nm) or more and 425 nm or less and 680 nm or more and 690 nm (preferably 685 nm) or less.

  FIG. 3 shows the characteristics of the dichroic mirror 7. The dichroic mirror 7 transmits green light (G light) of 500 nm to 585 nm and reflects other light.

  FIG. 4 shows the characteristics of the trimming filter 25. The trimming filter 25 reflects light having a wavelength of 500 nm to 590 nm and transmits other light.

  The spectral distribution of the color synthesized light W projected on the projection surface, determined by the UVIR cut filter 23, the dichroic mirror 7, and the trimming filter 25, is as shown in FIG. Further, the spectral distributions of R, G, and B are as shown by a solid line, an alternate long and short dash line, and a dotted line in FIG. The spectral distributions of R, G, and B are indicated by solid lines, alternate long and short dash lines, and dotted lines in other figures.

  The chromaticity coordinates by the spectral distribution shown in FIGS. 5 and 6 are xy chromaticity systems.

It becomes. However, the xy chromaticity system is a CIEI 1931 standard color system, and the above table 1 shows the coordinates normally expressed in the form of W, R, G or B = (x, y). It is. This is the same in all tables shown below.

  FIG. 7 shows the characteristics of the light amount correction filter 24 in this embodiment. The light quantity correction filter 24 has a transmittance for R light higher than 80% (preferably 85%, more preferably 90%) and a transmittance for B light and G light of 40% (preferably 50%) or more and 80% ( Preferably 75%, more preferably 70%) or less. Further, the light quantity correction filter 24 has a characteristic that the transmittance with respect to light in the wavelength region between the R light and the G light is lower than 40% (preferably 35%, more preferably 30%). More preferably, the light quantity correction filter 24 has a transmittance for R light of 90% or more, a transmittance of B light and G light of 40% or more and 70% or less, and further between R light and G light. The transmittance for light in the wavelength region is preferably 30% (more preferably 25%) or less.

  In FIGS. 8 and 9, a light amount correction filter 24 having the characteristics shown in FIG. 7 is inserted in the optical path, and the light amount correction filter 24 acts on the spectral distributions in FIGS. The spectral distribution is shown.

  Since the light amount of the B light and the G light is reduced by the action of the light amount correction filter 24, the light amount of the R light is relatively increased in FIGS.

  The chromaticity coordinates according to the spectral distribution of FIGS. 8 and 9 are xy chromaticity systems,

It becomes.

  As can be seen, the color coordinates of G are corrected in the direction in which the color gamut is expanded, and B and R are maintained in substantially the same state. Further, W1 = (0.30, 0.33), which is the color coordinate of W, is white represented by D65 (daylight spectrum distribution) = (0.31, 0.33) as shown in FIG. Is set in the vicinity of the color coordinate.

  Here, consider the case where a filter having the same characteristics as a conventional filter having no reflection band on the ultraviolet side as shown in FIG. FIG. 27 shows the characteristics of the filter similar to the conventional filter. FIGS. 28 and 29 show a spectrum obtained by inserting this filter into the optical path and acting on the spectral distributions of FIGS. Show the distribution.

  The chromaticity coordinates according to the spectral distribution of FIGS. 28 and 29 are xy chromaticity systems,

It becomes.

  In R and G, the color gamut is enlarged as in the present embodiment, but as shown in FIG. 10, the color coordinate W4 = (0.264, 0.335) of W is greatly deviated from the color coordinate of D65. . In order to bring this color (color coordinate W4) closer to the white color (color coordinate W1) according to the first embodiment, the amount of B light is decreased (indicated by arrow dB), and the amount of G light is further decreased (arrow). dG)). This greatly restricts the display range (dynamic range) of the liquid crystal panel.

  FIG. 13 shows a specific configuration of the light amount correction filter 24 in the first embodiment. Reference numeral 31 in FIG. 13 denotes a transparent glass substrate, and a first optical thin film 32 having a characteristic of reducing the amount of blue and green light by a predetermined ratio as shown in FIG. Is provided. Specifically, the first optical thin film 32 has a characteristic that the transmittance for R light is higher than 80% and the transmittance for B light and G light is 40% or more and 80% or less. More preferably, the transmittance for R light is 90% or more, and the transmittance for B light and G light is 40% or more and 70% or less.

  Further, on the second transmission surface, which is the surface opposite to the first transmission surface of the substrate 31, a second optical thin film 33 having a characteristic of reflecting green and red regions as shown in FIG. Is provided. Specifically, the second optical thin film 33 has a characteristic that the transmittance with respect to R, B, and G light is higher than 80%, and the transmittance with respect to light in a wavelength region between the R light and G light is lower than 40%. Have More preferably, the transmittance for R, B, and G light is 90% or more, and the transmittance for light in the wavelength region between the R light and G light is 30% or less.

  The first optical thin film 32 having the characteristics shown in FIG. 11 is configured by alternately laminating a high refractive index thin film layer and a low refractive index thin film layer. By this method, the reflectance of a predetermined wavelength band can be increased. At this time, the reflectance can be adjusted by selecting the number of high refractive index thin film layers and low refractive index thin film layers that are alternately stacked.

  Then, by inserting and removing the light amount correction filter 24 having such characteristics with respect to the optical path, the two color reproduction regions can be easily switched. By inserting the light quantity correction filter 24 in the optical path, an image with good white balance and color reproducibility can be projected. Further, since the light amount correction filter 24 is moved out of the optical path, the light amount is not reduced by the light amount correction filter 24, so that a bright image can be projected.

  Furthermore, in conjunction with the insertion and removal of the light quantity correction filter 24, various types of images are projected by changing the driving method of the reflective liquid crystal panel or controlling a variable diaphragm that restricts the luminous flux of the illumination system. It is also possible to do.

  The position of the light quantity correction filter 24 in this embodiment shown in FIG. 1 is merely an example, and any position may be used as long as it is a white light optical path from the light source lamp to the dichroic mirror 7.

  The light amount correction filter 24 is arranged on the optical path of white light in order to block most of light having a wavelength between R light and G light (70%, preferably 80%, more preferably 90% or more). Although it is desirable, the present invention is not limited to this. Even if it is not on the optical path of white light, it may be on the common optical path of G light and R light. Specifically, when the dichroic mirror 58 has a characteristic that separates the R light from the G light and the B light, the light amount correction filter 24 is provided on the rear side (light modulation element side) of the dichroic mirror 58. You may arrange. The same applies to the other embodiments. Note that the expression “common optical path of G light and B light” naturally includes an optical path of white light.

  In this embodiment, the light amount correction filter is a transmissive filter, that is, the light transmitted through the filter is guided to the light modulation elements 8, 9, 10 and the projection lens 22. However, the present invention is not limited to this. Specifically, the light amount correction filter may be a reflection type filter, that is, may be configured to guide the light reflected by the filter to the light modulation elements 8, 9, 10 and the projection lens 22. Of course, in the case of a reflection type filter, “transmittance” needs to be read as “reflectance” with respect to the characteristics of FIG.

  FIG. 14 shows the characteristics of a light amount correction filter that is Embodiment 2 of the present invention. Note that the optical configuration of the projector using the light amount correction filter of this embodiment is the same as that of the first embodiment (FIG. 1).

  15 and FIG. 16, a light amount correction filter having the characteristics shown in FIG. 14 is inserted in the optical path of white light from the light source lamp to the dichroic mirror 7 shown in FIG. 1, and the light amount correction filter is shown in FIGS. 6 shows the resulting spectral distribution acting on the spectral distribution of FIG.

  Since the light amount of the B light and the G light is decreased by the action of the light amount correction filter, the light amount of the R light is relatively increased in FIGS. 15 and 16.

  The chromaticity coordinates according to the spectral distribution of FIGS. 15 and 16 are xy chromaticity systems.

It becomes.

  In the present embodiment, the green region is set wider than in the first embodiment. According to the present embodiment, as shown in FIG. 10, the color coordinate W2 = (0.30, 0.32) of W is a coordinate of D65 = (0.31, 0.33) further than that of the first embodiment. Can be approached.

  FIG. 17 shows an optical configuration of a liquid crystal projector that is Embodiment 3 of the present invention. Since the basic configuration of the projector of the present embodiment is the same as that of the first embodiment (FIG. 1), the same components as those of the first embodiment are denoted by the same reference numerals as in the first embodiment, and the description is omitted. .

  However, in this embodiment, a dichroic mirror 58 having a characteristic different from that of the dichroic mirror 7 of the first embodiment is used. The light amount correction filter 56 is arranged between the first lens array 3 and the second lens array 4 as in the first embodiment, but is fixed on the optical path in this embodiment.

FIG. 18 shows the characteristics of the dichroic mirror 58 of this embodiment. The dichroic mirror 58 transmits light of 500 nm to 576 nm and reflects other light. As a result, the color purity of the G light is higher than that in the first embodiment. The characteristics of the trimming filter 25 are the same as those shown in FIG. 4. FIG. 19 shows the characteristics of the light quantity correction filter 53 of this embodiment. In FIGS. 20 and 21, a light amount correction filter 53 having the characteristics shown in FIG. 19 is inserted into the optical path, and the light amount correction filter 53 acts on the spectral distributions of FIGS. The spectral distribution is shown.

  The chromaticity coordinates according to the spectral distribution of FIGS. 20 and 21 are xy chromaticity systems.

It becomes.

  According to the present embodiment, in a state where the color gamut of the G color coordinate is wide, the color coordinate W3 does not require electrical correction using the liquid crystal panel, as shown in FIG. 0.31, 0.33) is set in the vicinity of the white color coordinate.

  The configuration of this embodiment emphasizes color reproduction area and contrast rather than brightness, and it is not necessary to switch between image projection that emphasizes brightness and image projection that emphasizes color reproduction area and contrast. It is a projector suitable for. For example, it is suitable for a projector that projects a movie exclusively in a movie theater.

  In the first to third embodiments, the optical system of the projector using the reflective liquid crystal panel has been described. However, the present invention can also be applied to the case where a transmissive liquid crystal panel as shown in FIG. 22 is used. .

  Reference numeral 51 denotes an arc tube such as a high-pressure mercury lamp, and 52 denotes a reflector. The arc tube 51 and the reflector 52 constitute a light source lamp. 53 is a first lens array, and 54 is a second lens array. Reference numeral 55 denotes a UVIR cut filter. 75 is a polarization conversion element, and 56 is a condenser lens.

  68, 69 and 70 are G, B and R transmissive liquid crystal panels, respectively. Reference numerals 57, 58, 59, 60 and 61 denote lenses for guiding illumination light from the light source lamp to the liquid crystal panels 68, 69 and 70. Reference numerals 62, 63, 64 and 65 denote reflection mirrors for bending the illumination light.

  66 is a first dichroic mirror and 67 is a second dichroic mirror. In this embodiment, a color separation system is configured by using two dichroic mirrors 66 and 67.

  74 is a trimming filter, 71 is a color synthesis prism, and 72 is a projection lens.

  Reference numeral 73 denotes a light amount correction filter which is an optical filter, and is provided so as to be able to be taken in and out of a region between the first and second lens arrays 53 and 54 (between the UVIR cut filter 55 and the second lens array 54). Yes. This loading / unloading is performed using a driving force of an actuator (not shown) according to a user's switch operation.

  White light from the light source lamp is divided into a plurality of light beams by the first and second lens arrays 53 and 54, and the first dichroic mirror is passed through the UVIR cut filter 55, the polarization conversion element 75, the condenser lens 56 and the reflection mirror 62. 66 is incident.

  The first dichroic mirror 66 transmits the B light, and the B light is guided to the B transmission type liquid crystal panel 69 via the reflection mirror 63 and the lens 58.

  Of the R light and G light reflected by the first dichroic mirror 66, the G light is reflected by the second dichroic mirror 67 and guided to the transmissive liquid crystal panel 68 for G through the lens 57. The R light transmitted through the second dichroic mirror 67 travels through the lenses 59, 60, 61 and the reflecting mirrors 64, 65, and is color-adjusted by the trimming filter 74 before being applied to the R transmissive liquid crystal panel 70. Led.

  A liquid crystal drive circuit (not shown) is connected to an image supply device (not shown) such as a personal computer, a DVD player, or a TV tuner. The liquid crystal driving circuit drives each transmissive liquid crystal panel based on image (video) information input from the image supply device, and forms an original image for each color. Thereby, the light incident on each transmissive liquid crystal panel is modulated (image modulation) according to the original image.

  The image-modulated B light and R light are reflected by the color synthesizing prism 71, and the G light is transmitted therethrough and directed to the projection lens 72. The three color lights (color images) color-synthesized by the color synthesis prism 71 are projected onto a projection surface such as a screen (not shown) by the projection lens 72.

  The characteristics of the UVIR filter 55 in this embodiment are the same as the characteristics shown in FIG.

  The characteristics of the first dichroic mirror 66, the second dichroic mirror 67, and the trimming filter 74 are shown in FIGS. 23, 24, and 25, respectively.

  The characteristics of the light quantity correction filter 73 are the same as those shown in FIGS. 7 and 14 in the first and second embodiments.

  FIG. 26 shows the spectral distribution when the light amount correction filter 73 is not inserted in the optical path, that is, the W and R of the light projected on the projection surface determined by the first and second dichroic mirrors 66 and 67 and the trimming filter 74. , G, B spectral distribution. The spectral distribution shown in FIG. 26 is substantially the same as the spectral distribution shown in FIG. For this reason, the same effect as in the first and second embodiments can be obtained by inserting the light amount correction filter 73 having the same characteristics as those described in the first and second embodiments into the optical path.

  As described above, according to the first, second, and fourth embodiments, it is possible to switch between a bright image projection state and an image projection state that emphasizes color reproducibility, and in any projection state. An image with high gradation and high contrast can be projected. Also in the third embodiment, it is possible to project an image with high gradation and high contrast.

  In each of the above embodiments, the first color light has been described as red light, the second color light as green light, and the third color light as blue light. However, the present invention is not limited to this, and the spectrum of light emitted from the light source The first to third color lights can be appropriately selected according to the distribution.

  In each of the above-described embodiments, the light amount correction filter has a transmittance for one color light of the first to third color lights higher than 80%, and a transmittance for the other two color lights is 40% or more and 80% or less. The case of having characteristics has been described. However, the present invention is not limited to this, and a light amount correction filter having a characteristic that the transmittance with respect to two color lights is higher than 80% and the transmittance with respect to the other one color light is 40% or more and 80% or less may be used. .

  Also, the above embodiments may be combined within a consistent range. For example, the light amount correction filter may be a reflective filter in all the embodiments, and the numerical value range of the transmittance of the light amount correction filter described in the first embodiment may be applied to other embodiments. The same applies to other matters.

  Further, in each of the embodiments described above, the case where the liquid crystal panel is used as the light modulation element has been described. However, the present invention is not limited to this, and other light modulation elements such as DMD (digital micromirror device) may be used. .

1 is a diagram illustrating a configuration of a reflective liquid crystal projector that is Embodiment 1 of the present invention. FIG. FIG. 3 is a characteristic diagram of the UVIR cut filter according to the first embodiment. FIG. 3 is a characteristic diagram of the dichroic mirror according to the first embodiment. FIG. 6 is a characteristic diagram of the trimming filter according to the first embodiment. FIG. 3 is a diagram illustrating a spectrum distribution on a projection surface in a state where a light amount correction filter is not inserted in an optical path in the first embodiment. FIG. 3 is a diagram illustrating a spectrum distribution on a projection surface in a state where a light amount correction filter is not inserted in an optical path in the first embodiment. FIG. 3 is a characteristic diagram of a light amount correction filter according to the first embodiment. FIG. 3 is a diagram illustrating a spectrum distribution on a projection surface in a state where a light amount correction filter is inserted in an optical path in the first embodiment. FIG. 3 is a diagram illustrating a spectrum distribution on a projection surface in a state where a light amount correction filter is inserted in an optical path in the first embodiment. The figure which shows the color coordinate of the white in Example 1 (-3). FIG. 6 is a characteristic diagram of the first optical film in Example 1. FIG. 6 is a characteristic diagram of the second optical film in Example 1. FIG. 3 is a perspective view illustrating a configuration of a light amount correction filter according to the first embodiment. FIG. 6 is a characteristic diagram of a light amount correction filter used in a reflective liquid crystal projector that is Embodiment 2 of the present invention. FIG. 10 is a diagram illustrating a spectral distribution on a projection surface in a state where a light amount correction filter is inserted in an optical path in the second embodiment. FIG. 10 is a diagram illustrating a spectral distribution on a projection surface in a state where a light amount correction filter is inserted in an optical path in the second embodiment. FIG. 6 is a diagram illustrating a configuration of a reflective liquid crystal projector that is Embodiment 3 of the present invention. FIG. 10 is a characteristic diagram of the dichroic mirror of Example 3. FIG. 10 is a characteristic diagram of a light amount correction filter according to a third embodiment. FIG. 10 is a diagram illustrating a spectrum distribution on a projection surface in a state where a light amount correction filter is disposed in an optical path in the third embodiment. FIG. 10 is a diagram illustrating a spectrum distribution on a projection surface in a state where a light amount correction filter is disposed in an optical path in the third embodiment. FIG. 10 is a diagram illustrating a configuration of a transmissive liquid crystal projector that is Embodiment 4 of the present invention. FIG. 10 is a characteristic diagram of the first dichroic mirror of Example 4. FIG. 10 is a characteristic diagram of the second dichroic mirror of Example 4. FIG. 10 is a characteristic diagram of the trimming filter according to the fourth embodiment. FIG. 10 is a diagram illustrating a spectrum distribution on a projection surface in a state where a light amount correction filter is inserted into an optical path in the fourth embodiment. The characteristic view of the conventional light quantity correction filter. The figure which shows the spectrum distribution in the to-be-projected surface in the state in which the conventional light quantity correction filter was inserted in the optical path. The figure which shows the spectrum distribution in the to-be-projected surface in the state in which the conventional light quantity correction filter was inserted in the optical path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 Light-emitting tube 3,4,53,54 Lens array 5,75 Polarization conversion element 6,56 Condenser lens 7,58,66,67 Dichroic mirror * 10 Reflective type liquid crystal panel 11,12,13 Phase plate 14,15 Polarizing beam splitter 18 Color selective phase plate 21, 71 Color synthesis prism 22, 72 Projection lens 23, 55 UVIR cut filter 24, 56 Light amount correction filter 25, 74 Trimming filter 31 Glass substrate 32 First optical thin film 33 Second Optical thin film 68, 69, 70 Transmission type liquid crystal panel

Claims (10)

A color separation system for separating light from the light source into first, second and third color lights;
An optical filter disposed on the light source side of the color separation system,
The optical filter has a characteristic that the transmittance for one or two of the first to third color lights is higher than 80%, and the transmittance for the other color lights is 40% or more and 80% or less. An optical system.   The optical filter has a transmittance with respect to the first color light higher than 80%, a transmittance with respect to the second and third color lights of 40% to 80%, and the first color light and the second color light. 2. The optical system according to claim 1, wherein the optical system has a characteristic that the transmittance with respect to light in a wavelength region between the first and second wavelengths is lower than 40%. The optical filter is
A transparent substrate;
A first layer provided on the first surface of the substrate, having a characteristic that the transmittance with respect to the first color light is higher than 80%, and the transmittance with respect to the second and third color lights is not less than 40% and not more than 80%. 1 optical film;
The substrate is provided on a second surface opposite to the first surface of the substrate, and has a transmittance of greater than 80% for the first, second, and third color lights, and the first color light and the first color light The optical system according to claim 2, wherein the optical system includes a second optical film having a characteristic that the transmittance with respect to light in a wavelength region between the two colored lights is lower than 40%.   4. The optical according to claim 1, wherein the first color light is red light, the second color light is green light, and the third color light is blue light. 5. system.   The optical system according to claim 1, wherein the optical filter is a reflective filter.   The optical system according to claim 1, wherein the optical filter can be taken in and out of the optical system. A color separation system that decomposes light from the light source into red light, green light, and blue light;
An optical filter disposed on a common optical path of the green light and the blue light,
The optical system is characterized in that the transmittance for the red light is higher than 80% and the transmittance for the green light and the blue light is 40% or more and 80% or less. Three light modulation elements to which three color lights from the color separation system are respectively guided;
A synthesis system for synthesizing the three color lights from the three light modulation elements;
The optical system according to claim 1, further comprising: a projection lens that projects light synthesized by the synthesis system.   An image projection apparatus which projects an image using the optical system according to claim 8. An image projection device according to claim 9,
An image display system comprising: an image supply device that supplies image information to the image projection device.