JP5153371B2 - Image projection device - Google Patents

Description

  The present invention relates to an image projection apparatus, and is suitable for a color projector that enlarges and projects a projected image original image based on, for example, a liquid crystal panel (image display element) or DMD on a screen surface.

  2. Description of the Related Art Conventionally, various image projection apparatuses (projectors) have been proposed in which a projected image original image based on an image display element such as a liquid crystal panel or DMD is enlarged and projected on a screen surface.

  In these projectors, in order to obtain a large screen image (projection image), an optical image corresponding to the image signal is formed on a light valve (image display element), and the optical image is irradiated with light and projected onto the screen by a projection lens. Enlarging and projecting.

  Among these, an image projection apparatus that uses three light valves corresponding to the three primary color lights of red, green, and blue light and has high luminance, high resolution, and good color reproducibility is well known.

  FIG. 23 is a schematic configuration diagram of an image projection apparatus using three light valves (liquid crystal panels). In this image projection apparatus, the light beam emitted from the light source 101 is used to illuminate the liquid crystal panels 108, 109, and 110, which are the illuminated surfaces, using the parabolic reflector 102 and the first and second fly-eye lenses 103 and 104. ing. In the illumination optical system that illuminates the surface to be illuminated with light from this light source, a polarization conversion element 105 that aligns the polarization direction of the illumination light with S-polarized light, a condenser lens 106, a color separation optical system 107, and the like are arranged. . An image formed by the liquid crystal panels 108, 109, and 110 illuminated by the illumination optical system is projected and enlarged on the screen S by the projection lens 111.

  Here, the optical action in the color separation optical system 107 will be described. The white light collected from the condenser lens 106 is decomposed into two colors of G light and RB light by the dichroic mirror 112.

  Here, G light is transmitted through the dichroic mirror 112, and RB light is reflected from the dichroic mirror 112. The G light transmitted through the dichroic mirror 112 is detected by the polarizing plate 113, reflected by the first deflection / separation prism 114, transmitted through the G phase plate 115, and illuminates the G reflective image display element 108. .

  The light whose polarization state is modulated based on the G image by the reflective liquid crystal display element 108 for G passes through the first polarization separation prism 114 and passes through the second deflection separation prism 116. The projection lens 111 is reached.

  On the other hand, the s-polarized RB light reflected by the dichroic mirror 112 is detected by the polarizing plate 117, and only the B light is rotated to the P-polarized light by the wavelength-selective phase plate 118, whereby the R light and the B light are mutually converted. Different polarization directions. The R light is reflected by the third polarization separation prism 119, passes through the R phase plate 120, and illuminates the R reflective image display element 110.

  The light whose polarization state is modulated by the R reflective liquid crystal display element 110 based on the R image is transmitted through the third polarization separation prism 119 and rotated by the wavelength selective phase plate 121. The second polarized light separating prism 116 is reflected and reaches the projection lens 111.

The B light passes through the third polarization separation prism 119, passes through the B phase plate 122, and illuminates the B reflection type image display element 109 .

The light whose polarization state is modulated by the reflective liquid crystal display element 109 for B based on the image for B is reflected by the third polarization separation prism 119 and reflected by the second polarization separation prism 116. The projection lens 111 is reached.

  In general, an image projection apparatus may realize a color reproduction region that cannot be achieved only by color separation and synthesis. At this time, as shown in FIG. 24, an image projection apparatus is known in which a color correction filter 123 is inserted between the light source 1 and the dichroic mirror 112 to enlarge the color reproduction region (Patent Document 1).

  In the example of FIG. 24, a color correction filter 123 is disposed between the polarization conversion element 105 and the condenser lens 106.

For example, the color correction filter 123 has a spectral transmission characteristic shown in FIG. The spectral characteristics of the color correction filter 123 exhibit a notch portion NM that cuts an orange region in the vicinity of a wavelength of 580 nm, and a half mirror characteristic portion HM with respect to a BG band corresponding to a complementary color of the orange region.

By cutting the orange part, the purity of green can be increased and the color reproduction area is expanded. However, by cutting the orange part, the chromaticity coordinates of the white light are greatly shifted to the cyan side, so the BG band corresponding to the complementary color of the orange area is made a half mirror to adjust the chromaticity coordinates of the white light. Is going. Since the color reproduction area is expanded and white chromaticity coordinate adjustment is performed using only the color correction filter, there is little reduction in contrast.
JP2004-219727

  In an image projection apparatus using a conventional color correction filter, color unevenness tends to occur in the screen surface.

  In general, a mode for introducing a color correction filter includes a color priority mode and a D65 mode. In these modes, the y value of the white chromaticity coordinates is lower than the mode in which no color correction filter is inserted.

  FIG. 26 shows a Macadam ellipse (10 times magnification) in the xy chromaticity diagram. This means that the colors in the ellipse look the same for humans. Therefore, the green part with a large elliptical shape looks the same color even if the chromaticity coordinate changes slightly, and conversely the red part and the blue part with a small elliptical shape with respect to the green part can be seen with a slight change in chromaticity coordinate. Different.

  When the color correction filter is inserted, the white chromaticity coordinates may be changed from red to blue before the insertion, so that the white chromaticity coordinate deviation in the screen surface may be at an unacceptable level. When the color correction filter is inserted, the white chromaticity coordinates are also adjusted, so that the color unevenness cannot be corrected, and the unevenness may remain in the screen.

  It is an object of the present invention to provide an image projection apparatus that can expand a color reproduction region that cannot be achieved by color separation and synthesis alone, and that can generate a projection image with good image quality with little occurrence of color unevenness in the projection image. .

Image projection apparatus of the present invention decomposes the first controlled based on the image signal, and the second, third image display device, a light beam emitted from the light source unit first, second, and third color light, wherein the first color light to illuminate the first image display device, the second by two-color light illuminating the second image display device, the third color-separation optical illuminating the third image display element by color light In an image projection apparatus having an illumination optical system including a system, and a projection optical system that projects a light beam from the first, second, and third image display elements onto a projection surface,
The illumination optical system has a color correction filter in an optical path between the light source means and the color separation optical system,
The wavelength band of the first color light that illuminates the first image display element includes at least 450 nm to 480 nm,
The wavelength band of the second color light that illuminates the second image display element includes at least 510 nm to 540 nm,
The wavelength band of the third color light that illuminates the third image display element includes at least 610 nm to 640 nm,
The color correction filter has an average transmission in a wavelength band including a complementary color component of a certain wavelength within a range of 550 nm to 600 nm and having a transmittance for light of a certain wavelength of less than 60% and in a range of 420 nm to 580 nm. The rate is in the range of 70% to 90%,
When the first image display element is controlled so that all of the illumination light for illuminating the first image display element is guided to the projection optical system, the light is guided from the first image display element to the projection optical system. When the second image display element is controlled so as to guide the light to be emitted to the first illumination light and all the illumination light to illuminate the second image display element to the projection optical system, the second image Controls the third image display element so that the light guided from the display element to the projection optical system is guided to the second illumination light, and all the illumination light that illuminates the third image display element is guided to the projection optical system. In this case, when the light guided from the third image display element to the projection optical system is the third illumination light,
The chromaticity coordinate in the white xy chromaticity diagram of an arbitrary point of the image projected on the projection surface is
0.28 ≦ x ≦ 0.34
0.29 ≦ y ≦ 0.36
To be within the range of
When performing a white display, the first image display element, the light intensity of the first image light guided from said first image display element to the projection optical system, 50% of the first amount of illumination light Adjusted to 95% or less,
When performing a white display, the second image display element, wherein a second of the second image light quantity of the image display element is guided to the projection optical system, 70% of the light quantity of the second illumination light Adjusted to 95% or less,
When performing a white display, the third image display element, the third a third quantity of image light guided from the image display element to the projection optical system, the third 90% of the light amount of the illumination light It is characterized in that it is adjusted to be 100% or less.

  According to the present invention, it is possible to provide an image projection apparatus that projects an image with good image quality with less color unevenness.

  The image projection apparatus of the present invention comprises a light source means 1, first, second and third liquid crystal display elements (image display elements), an illumination optical system (illumination apparatus) for illuminating those liquid crystal display elements, and their A projection optical system (projection lens) that projects image light from the liquid crystal display element. The first, second, and third liquid crystal display elements are controlled (driven) based on image signals input from the outside or stored in a storage medium (by a control circuit (not shown)). .

The illumination device has a color correction filter that can be inserted into and removed from the optical path and a color separation / synthesis optical system. The color correction filter has a transmittance of less than 60% at one wavelength (for example, one wavelength within a range of 550 nm to 600 nm, preferably 570 nm to 590 nm, preferably 5 nm or more as a wavelength). . The color correction filter may have any characteristics as long as the transmittance is less than 60%. For example, even if the reflectance is 40% or more and the absorptance is 40% or more, the reflectance and the absorptivity are added. The combined value may be 40% or more.

  In addition, a substantially uniform transmittance (half mirror characteristic) within a range of 70% to 90% average transmittance in a wavelength band including a complementary color component of one wavelength (for example, one wavelength within a range of 420 nm to 580 nm). It has characteristics.

  In the other wavelength region (wavelength 600 nm to 700 nm) in the visible light region, the filter has a transmittance of nearly 100% (a dichroic mirror for transmission).

  Furthermore, in the first, second, and third liquid crystal display elements, the following electrical adjustment is performed.

Output intensity of the first wavelength band (blue light, B light, wavelength 420 nm to 500 nm, including at least 450 nm to 480 nm) that illuminates the first image display element 10 (first image with respect to the first illumination light) The ratio of light) is electrically adjusted to a level between 50% and 95%.

Output intensity of light in the second wavelength band (green light, G light, wavelength 500 nm to 580 nm including at least 510 nm to 540 nm) that illuminates the second image display element 8 (second image light with respect to the second illumination light) Is adjusted to a level of 70% to 95%.

Output intensity of light in a third wavelength band (red light, R light, wavelength 580 nm to 650 nm including at least 610 nm to 640 nm) that illuminates the third image display element 9 (third image light with respect to the third illumination light) Is adjusted to a level of 90% to 100%.

  In this embodiment, the amount of light is adjusted by using a color correction filter that functions mainly for light in the visible light region (400 nm to 700 nm, preferably 420 nm to 650 nm), or electrical adjustment is performed.

  Here, the electrical adjustment refers to the following when, for example, the first to third image display elements are liquid crystal display elements (liquid crystal panels).

  In the case of a liquid crystal panel, black and white display is generally performed by rotating or non-rotating the polarization state by turning the voltage on and off. For example, when the voltage is 0 V during black display and the voltage is 10 V during white display, halftone (gray) can be expressed between 0 V and 10 V. Here, electrical adjustment means that a voltage between 0 and 10 V (eg, a voltage of 8 V) is applied instead of 10 V when white is displayed, and the polarization direction is not rotated completely (90 degrees), but the polarization direction of only part of the light is rotated. To reduce the amount of light.

  For example, when the first image display element displays white, normally, the first image display element converts all of the light (first illumination light) that illuminates the first image display element to the first image light. A phase difference is given to the illumination light so as to be guided to the projection optical system. However, here, the first image display element has a phase difference with respect to the illumination light so that 50% or more and 95% or less of the light illuminating the first image display element is guided to the projection optical system. Is granted. This is because, when displaying white, when the image display element is controlled so as to guide all illumination light to the projection optical system, the amount of light guided to the projection optical system (which may be considered as all illumination light) is 50. It can also be said that 95% to 95% is guided to the projection optical system. The following can also be said. When the first image display element is illuminated with the first linearly polarized light and white is desired to be displayed, usually all the illumination light is converted into the second linearly polarized light (image light). Only 50% to 95% of the light is converted into the second linearly polarized light. Of course, when the first linearly polarized light is used as image light (configured to be guided to the projection optical system), the opposite is true, and only 50% or more and 95% or less of the illumination light remains as the first linearly polarized image. The light is emitted from the display element. The description of this electrical adjustment is the same for the second and third image display elements described below, and of course, the same is true for each embodiment described below.

  In the present embodiment, it is more preferable to electrically adjust the image light in the first wavelength band to a level of 50% to 85% in the first image display element. In the second image display element, it is more preferable to electrically adjust the image light in the second wavelength band to a level of 70% to 85%. Furthermore, it is preferable to electrically adjust the image light in the third wavelength band to a level of 90% or more and 100% or less in the third image display element.

  Black and white in the DMD panel is expressed by the angle of the mirror on the surface of the DMD panel. In the white display, the light incident on the mirror is tilted in a direction 1 where the light enters the projection lens, and in the black display, the light incident on the mirror is tilted in a direction 2 where the light does not enter the projection lens.

  A halftone can be expressed by tilting between direction 1 and direction 2 described above.

  Electrical adjustment is to reduce the amount of light by tilting between directions 1 and 2 during white display so that light is not completely incident on the projection lens but partially reflected from the projection lens. Using this principle, even in an image projection apparatus using a DMD panel, the balance of color (white) is adjusted by intentionally reducing the amount of light at the time of white display in displaying some color light (color unevenness is reduced). Reduced).

  Next, the image projection apparatus of the present invention will be described with reference to each drawing.

  FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention. In the figure, reference numeral 1 denotes a light source (light source means) that emits white light with a continuous spectrum. A reflector 2 condenses light from the light source 1 in a predetermined direction.

  Reference numeral 3 denotes a first light beam splitting member. Reference numeral 4 denotes a second light beam splitting member. The first light beam splitting member 3 and the second light beam splitting member 4 are each composed of a fly-eye lens array (a fine optical element is two-dimensionally arranged) having a plurality of fine optical elements. The light from the means 1 is divided into a plurality of light fluxes.

  The first beam splitting member 3 is also called a first lens array, and the second beam splitting member 4 is also called a second lens array. Reference numeral 23 denotes a UVIR cut filter that cuts out (shields) ultraviolet light and infrared light. Reference numeral 24 denotes a color correction filter that can be inserted and removed from the optical path.

  A polarization conversion element 5 emits incident non-polarized light in alignment with predetermined polarized light. A condensing optical system 6 is composed of a condenser lens. Each member 2-6 comprises the illumination optical system.

A dichroic mirror 7 transmits G light and reflects B light and R light. Reference numeral 25 denotes a trimming filter. Reference numerals 10, 8, and 9 denote first, second, and third image display elements (light valves) provided on different irradiated surfaces.

  The image display elements 8 to 10 reflect light, modulate the image, and display an image in the order of displaying the green (G) reflective liquid crystal display element (liquid crystal panel) and red (R) reflective liquid crystal. It is a reflective liquid crystal display element (liquid crystal panel) for display elements (liquid crystal panel) and blue (for B).

  Reference numerals 11, 12, and 13 denote G, R, and B phase plates (¼ wavelength plates), respectively. Reference numeral 14 denotes a first polarization beam splitter. Reference numeral 15 denotes a second polarization beam splitter. Reference numeral 16 is a first polarizing plate, and 17 is a second polarizing plate. A color selective phase plate 18 converts the polarization state of the R light by 90 degrees and does not convert the polarization state of the B light. Reference numeral 19 is a third polarizing plate, and 20 is a fourth polarizing plate. Reference numeral 21 denotes a color synthesis prism that reflects the G projection light and transmits the B and R projection lights. Reference numeral 22 denotes a projection lens (projection optical system).

  Each member 7, 11-21 constitutes a color separation optical system.

  Next, the optical action will be described. Light emitted from the light source means 1 is reflected and collected in a predetermined direction by the reflector 2.

  Here, the reflecting surface of the reflector 2 has a parabolic shape, and the light from the light emitting point of the light source means 1 provided at the focal position of the parabolic surface is reflected by the reflecting surface having the parabolic shape, and then the symmetry axis. The luminous flux is parallel to

  The condensed light beam from the reflector 2 enters the first lens array 3. Thereafter, the light enters the second lens array 4 through the UVIR cut filter 23 and the color correction filter 24.

  The first lens array 3 is configured by combining a plurality of micro lenses having a positive refractive power whose outer shape is a rectangle in a matrix. Then, the incident light beam is divided into a plurality of light beams corresponding to each microlens and condensed, and the second light source image (first light emission point image) is converted into a polarized light through the second lens array 4. It is formed in the vicinity of the element 5.

  As shown in FIG. 27, the polarization conversion element 5 has a configuration in which a plurality of polarization conversion parts 5d each including a polarization separation element 5a, a reflection surface 4b, and a half-wave plate 5c are arranged in a matrix.

  In FIG. 27, only one polarization converter 5d is shown. A plurality of light beams condensed in a matrix form are incident on the polarization separation surface 5a corresponding to the column, and are split into a P-polarized component light LP that is transmitted and a S-polarized component light LS that is reflected.

  The reflected S-polarized component light is reflected by the reflecting surface 5b, emitted in the same direction as the P-polarized component, transmitted through the half-wave plate 5c, converted into the same polarized component as the P-polarized component, and the polarization direction is changed. It emits as uniform light.

  The plurality of light beams that have undergone polarization conversion are condensed in the vicinity of the polarization conversion element 5 and then reach the condensing optical system (illumination light lens) 6 as divergent light beams. The illumination light is aligned in a predetermined polarization state by the polarization conversion element, and the illumination light emitted from the condenser lens 6 is divided into G light and RB light by the dichroic mirror 7.

  The G light is polarized by the polarizing plate 16, passes through the polarizing beam splitter 14 and the phase plate 11, and reaches the reflection liquid crystal display element 8 for G.

  The R light and the B light are polarized by the polarizing plate 17 through the trimming filter 25, and only the B light is converted into a polarization state orthogonal to the incident state by the color selective phase plate 18.

  The R light is reflected by the polarization beam splitter 15 and reaches the reflection liquid crystal display element 9 for R via the phase plate 12.

  The B light passes through the polarization beam splitter 15 and reaches the B reflection type liquid crystal display element 10 at a position different from the R reflection type liquid crystal display element 9 via the phase plate 13.

  The reflected light modulated by the reflective liquid crystal display element 8 for G is reflected by the polarizing beam splitter 14 via the phase plate 11, analyzed by the polarizing plate 19, reflected by the color synthesis prism 21, and projected by the projection lens. To 22.

  The light modulated and reflected by the reflective liquid crystal display element 9 for R passes through the polarization plate splitter 15 through the phase plate 12, passes through the color synthesis prism 21 through the phase plate 20, and reaches the projection lens 22. .

  The light modulated and reflected by the reflective liquid crystal display element 10 for B is reflected by the polarizing beam splitter 15 through the phase plate 13, analyzed by the polarizing plate 20, passed through the color synthesizing prism 21, and the projection lens. To 22.

  The light of each color combined by the color combining prism 21 is projected as an image on a screen (projected surface) S provided on a predetermined surface by the projection lens 22.

  In the present embodiment, the color filter 24 that converts the color of the illumination light is provided between the first lens array 3 and the second lens array 4.

  FIG. 2 is an explanatory diagram of the spectral characteristics of the UVIR cut filter 23. The UVIR cut filter 23 cuts light with a wavelength of 425 nm or less and light with a wavelength of 680 nm or more from illumination light.

  FIG. 3 is an explanatory diagram of the spectral characteristics of the dichroic mirror 7. The dichroic mirror 7 transmits light having a wavelength of 550 nm to 585 nm and reflects light having other wavelengths.

  FIG. 4 is an explanatory diagram of the spectral characteristics of the trimming filter 25. The trimming filter 25 reflects light having a wavelength of 550 nm to 590 nm and transmits light having other wavelengths.

  As a result of using these optical elements, the spectral distribution (spectral intensity, spectral distribution) of W (white light) of the light projected on the screen S is as shown in FIG. Further, the spectral distribution (spectral intensity, spectral distribution) of RGB light is as shown in FIG.

The chromaticity coordinates based on the spectral distributions of FIGS. 5 and 6 are xy chromaticity systems. W = (0.30, 0.36)
B = (0.15, 0.04)
G = (0.36, 0.63)
R = (0.65, 0.35)
It becomes.

  FIG. 7 is a spectral characteristic diagram of the color correction filter 24 in this embodiment. The vertical axis represents the transmittance T (expressed as a ratio).

The color correction filter 24 of the embodiment is disposed in the optical path between the light source means and the color separation / synthesis system. The color correction filter has a reflectance of one wavelength of 40% or more (transmittance of less than 60%) and an average transmittance of a wavelength band including a complementary color component of one wavelength of 70% or more and 90% or less. Has half mirror characteristics.

Specifically, the color correction filter 24 of this embodiment is coated on both surfaces of the light incident / exit surface. And one side is a transmission part of notch shape NM. The opposite surface is in the half mirror unit HM consisting substantially uniform transmittance with respect to wavelength band range of visible light. The other wavelength band is a dichroic mirror surface having a transmission band TM with a transmittance close to 100%.

  Here, the central wavelength of the notch NM is 580 nm, and the color correction filter 24 has a transmittance of 40% or less (20% in FIG. 7) for light in the wavelength region centered at 580 nm (orange light). It is. That is, 60% or more (80% in FIG. 7) of light in the wavelength region centered at 580 nm (orange light, light in a wavelength region having a width of 10 nm or more) is shielded (cut).

  In addition, the color correction filter 24 has a transmittance (light quantity) with respect to B light and G light (400 nm or more and 560 nm or less, light on a shorter wavelength side than the above-described orange light) within a range of 70% to 90% ( In FIG. 7, it is 75%). That is, 10% or more and 30% or less (25% in FIG. 7) of B light and G light are blocked.

  Further, the transmittance of the color correction filter 24 with respect to the R light, that is, light in a wavelength region of 600 m or more and 670 nm or less (light in a longer wavelength side than the wavelength region of the orange light in the visible light region) is approximately 100. % (98% or more), and substantially all of the R light is transmitted.

  When the color correction filter 24 having such spectral characteristics and a light source having a spectral distribution as shown in FIGS. 5 and 6 are used, the spectral distribution of W (white) light projected on the screen S is shown. FIG. 9 shows the spectral distribution of RGB light.

Since the light amounts of the B light and the G light are decreased, the graphs in FIGS. 8 and 9 are such that the light amount of the R light is relatively increased. The chromaticity coordinates at this time are W = (0.298, 0.313)
B = (0.15, 0.04)
G = (0.32, 0.67)
R = (0.65, 0.35)
It becomes.

  As a result, the color coordinates of the G light are corrected in the direction in which the color gamut is expanded, and the B light and the R light are maintained in substantially the same state.

  However, the white coordinates are far from the target D65 (0.313, 0.329).

  Therefore, in this embodiment, the first wavelength band for illuminating the first image display element is electrically adjusted to a level of 50% to 95%. The second wavelength band for illuminating the second image display element is electrically adjusted to a level of 70% to 95%. Further, the third wavelength band for illuminating the third image display element is electrically adjusted to a level of 90% to 100%.

  Specifically, in this embodiment, the reflectance of the reflective liquid crystal display element is adjusted to 80% for the B light and 90% for the G light by the above-described electrical method (electrical adjustment), thereby adjusting the white coordinates (at the time of white display). The color coordinates of the image light are arranged in the vicinity of D65. At this time, the reflectance of the R light is approximately 100% electrically. The reflectance of the reflective liquid crystal display element is not the reflectance of the liquid crystal display element, but is reflected by the liquid crystal display element with respect to the light incident on the liquid crystal display element, and is analyzed (analyzed) by a polarizing beam splitter or a polarizing plate. ) Refers to the percentage of light emitted. The same applies to the transmittance of the liquid crystal display element described below.

  Here, the reflectance of 100% indicates the maximum utilization efficiency value of the liquid crystal display element.

  For example, if the maximum utilization efficiency of the liquid crystal display element is 70%, a reflectance of 50% means that 0.35 (1 × 0.7 × 0.5) light is directed onto the screen for one incident illumination light. Means that.

  When the color correction filter 24 and the effect of electrical adjustment are combined (added together), the same effect as that obtained by inserting a color correction filter having spectral characteristics as shown in FIG. 10 into the optical path can be obtained. As can be seen from FIG. 10, there is a difference in level between the B band and the G band. The color correction filter 24 has a half mirror portion (a region where the transmittance is substantially uniform (within ± 5%)) and a degree of electrical adjustment, so that the white color can be adjusted without impairing the brightness as much as possible. It can be performed.

  Hereinafter, color unevenness correction of the projected image on the screen S will be described.

  Generally, since there is in-plane unevenness of the transmittance or reflectance of the liquid crystal display element, color unevenness occurs in an image projected on the screen S by combining RGB light.

  In this embodiment, the color unevenness generated on the screen S is corrected when the electric adjustment is performed. More specifically, the balance of RGB light constituting the white at the center of the screen after the color correction filter 24 is turned on is used as a reference.

  For example, as shown in FIG. 11, it is assumed that B light is 90% and G light is 110% with respect to R. When the white coordinate is adjusted to D65 by electrical adjustment in the same way as the screen center, the reflectance of the reflective liquid crystal display element for B light and G light is adjusted to about 90% and about 80%, respectively, as shown in FIG. Just do it. As a result, the amount of unevenness and the amount of electrical adjustment are combined and the B light is 80% and the G light is 90% as shown in FIG. 13, and the screen center value is electrically 80% for the B light and 90% for the G light. It agrees with the result of the adjustment.

  In the present embodiment, the color correction filter 24 is inserted in the optical path, and the white light chromaticity coordinates in the electric adjustment mode are adjusted so as to fall within the following ranges.

0.28 ≦ x ≦ 0.34
0.29 ≦ y ≦ 0.36
Here, the above range may be considered as the vicinity of D65, and if it is inside a circle having a radius of 0.2, preferably a circle having a radius of 0.1, centered on the coordinates of D65, the vicinity of D65 (or D65). You may think that it is located in.

  In this way, when the white coordinate is adjusted electrically, the degree of adjustment is changed to correct the color unevenness on the screen, thereby realizing a white in which the unevenness is not noticeable in the vicinity of D65, which is highly sensitive to color deviation for human eyes. be able to.

  The color correction filter 24 of this embodiment is formed of a reflection type optical filter and does not generate heat. The position of the color correction filter 24 is not limited to the position shown in FIG. 1, and may be an optical path of white light from the reflector 1 to the dichroic mirror 7.

  Thus, two color reproduction regions can be easily realized by putting the color correction filter 24 in and out of the optical path. When the color correction filter 24 is not provided, a large amount of light is projected, so that a bright image can be projected.

  Furthermore, in conjunction with the insertion / removal of the color correction filter 24 in the optical path, the driving method of the reflective liquid crystal image display element is switched, and the diaphragm that restricts the luminous flux of the illumination light is controlled, so that more image states can be obtained. It can also be realized.

  FIG. 14 is an explanatory diagram showing the spectral characteristics of the color correction filter according to the second embodiment of the present invention. The color correction filter of Example 2 has a transmittance of about 5% with respect to light in the wavelength region centered at 580 nm (orange light), and shields (reflects or absorbs) 95% of the light in this wavelength region. Or scattering). Further, B light and G light (transmittance (light quantity) with respect to 400 nm or more and 560 nm or less is 80%, and transmittance with respect to R light is almost 100% (98% or more).

  When a color correction filter having such spectral characteristics and a light source having a spectral distribution as shown in FIGS. 5 and 6 are used, the spectral distribution of W (white) light projected on the screen S is shown in FIG. FIG. 15 shows the spectral distribution of RGB light.

The chromaticity coordinates based on the spectral distributions of FIGS. 15 and 16 are xy chromaticity systems. W = (0.288, 0.296)
B = (0.15, 0.04)
G = (0.28, 0.69)
R = (0.65, 0.35)
It becomes.

  In the second embodiment, the green (G light) region is set wider.

  The white coordinate is deviated from D65 (0.313, 0.329) as in Example 1, and the white coordinate is adjusted to D65 by adjusting the B light to 70% and the G light to 90% by electrical adjustment. ing.

  As in the first embodiment, the reflectance of R light is electrically 100%.

  When such a color correction filter 24 and the effect of electrical adjustment are combined (added together), the same effect is obtained as when a color correction filter having spectral characteristics as shown in FIG. 17 is inserted in the optical path.

  As can be seen from FIG. 17, there is a difference in level between the B band and the G band. Since it is possible to give a degree of freedom to the half mirror portion of the color correction filter and the degree of electrical adjustment, it is possible to perform white color adjustment without impairing the brightness as much as possible.

  In this embodiment, the color unevenness on the screen before the color correction filter is input is also corrected at this time. The method of correcting color unevenness is the same as that in the first embodiment.

  The illumination system of the image projection apparatus provided with the color correction filter is the same as that of the first embodiment.

  Examples 1 and 2 are image projection apparatuses (projectors) using a reflective image display element. On the other hand, Example 3 is an image projection apparatus using a transmissive image display element as shown in FIG.

  In FIG. 18, the same members as those shown in FIG. Reference numerals 68, 69, and 70 denote transmission image display elements for G, B, and R light, respectively. Reference numerals 57, 58, 59, 60, 61 denote illumination system lenses for guiding illumination light to the corresponding image display elements.

  Reference numerals 62, 63, 64 and 65 denote reflection mirrors for bending the illumination light. Reference numeral 66 denotes a first dichroic mirror and 67 denotes a second dichroic mirror. 74 is a trimming filter. Reference numeral 71 denotes a color synthesis prism. The color correction filter 24 has the same spectral characteristics as in the first embodiment.

  The UVIR filter 23 has the same spectral characteristics as in FIG.

  19, 20, and 21 are explanatory diagrams of spectral characteristics of the first dichroic mirror 66, the second dichroic mirror 67, and the trimming filter 74, respectively.

  Of the white light reflected by the reflection mirror 62, the B light is transmitted by the first dichroic mirror 66 and guided to the image display element 69 via the reflection mirror 63 and the illumination light lens 58.

  On the other hand, of the R light and G light reflected by the first dacromirror 66, the G light is reflected by the second dichroic mirror 67 and guided to the image display element 68 via the illumination light lens 57. The R light transmitted through the second dichroic mirror 67 is color-adjusted by the trimming filter 74 via the reflection mirror 64, the illumination light lens 60, the reflection mirror 65, and the illumination light lens 61, and then applied to the image display element 70. Led.

  The WRGB spectral distribution of the light projected onto the screen S by these optical elements is a spectral distribution as shown in FIG.

  As a result, the spectral distribution (FIG. 5) shown in the first embodiment is the same, and the effect of the color correction filter 24 shown in the first and second embodiments is not changed. That is, the present invention can be applied to a transmissive projector as well as a reflective projector.

  As described above, according to each embodiment, it is possible for the user to project an image according to the purpose by switching between a bright state and a state in which color is emphasized. In either projection state, a bright image with high contrast and inconspicuous color unevenness can be obtained.

FIG. 3 is a diagram illustrating an optical arrangement according to the first embodiment. Fig. 1 UV filter characteristics Characteristic diagram of dichroic mirror in Fig. 1 Characteristic diagram of dichroic mirror in Fig. 1 Diagram of spectral distribution in the absence of the color correction filter of Example 1 Diagram of spectral distribution by RGB in a state without the color correction filter of Example 1 Characteristic diagram of correction filter of Example 1 Fig. 6 is a spectrum distribution in a state where the color correction filter of Example 1 is inserted. Diagram of spectral distribution by RGB in a state where the color correction filter of Example 1 is inserted The characteristic diagram which combined the effect of the color correction filter and electric adjustment of Example 1 Model diagram showing color unevenness of a certain point on the screen of Example 1 The figure which shows the electric adjustment amount of the color nonuniformity part of Example 1. The figure which shows the RGB ratio after the electrical adjustment of the color nonuniformity part of Example 1. Characteristic diagram of correction filter of Example 2 Fig. 11 is a spectrum distribution in a state where the color correction filter of Example 2 is inserted. Diagram of spectral distribution by RGB in a state where the color correction filter of Example 2 is inserted The characteristic diagram which combined the effect of the color correction filter of Example 2, and the electric adjustment FIG. 6 is a diagram illustrating an optical arrangement according to the third embodiment. Characteristic diagram of first dichroic mirror in optical arrangement of embodiment 3 Characteristics diagram of second dichroic mirror in optical arrangement of embodiment 3 Characteristic diagram of trimming filter in optical arrangement of embodiment 3 Diagram of spectral distribution in the absence of the color correction filter of Example 3 Optical layout without conventional color correction filter Optical layout with the conventional color correction filter installed Characteristics of conventional color correction filters Macadam ellipse in the xy chromaticity diagram 1 is an explanatory diagram of a part of FIG.

Explanation of symbols

1 light source, 2 reflector, 3 first lens array, 4 second lens array, 5 polarization conversion element, 6 condenser lens, 7 dichroic mirror, 25 trimming filter, 8, 9, 10 G, R, B reflection Type liquid crystal display element, 11, 12, 13 G, R, B phase plate, 14 first polarizing beam splitter, 15 second polarizing beam splitter, 16 first polarizing plate, 17 second polarizing plate, 18 Color selective phase plate, 19 3rd polarizing plate, 20 4th polarizing plate, 21 color composition prism, 22 projection lens, 23 UVIR cut filter, 24 color correction filter

Claims (1)

First controlled based on the image signal, and the second, third image display device, a light beam emitted from the light source unit first, second, and separated into the third color light, the first by the first color light illuminates the image display element, and the second by two-color light illuminating the second image display device, an illumination optical system including the third color light by the color separation optical system for illuminating said third image display element, In an image projection apparatus having a projection optical system that projects a light beam from the first, second, and third image display elements onto a projection surface,
The illumination optical system has a color correction filter in an optical path between the light source means and the color separation optical system,
The wavelength band of the first color light that illuminates the first image display element includes at least 450 nm to 480 nm,
The wavelength band of the second color light that illuminates the second image display element includes at least 510 nm to 540 nm,
The wavelength band of the third color light that illuminates the third image display element includes at least 610 nm to 640 nm,
The color correction filter has an average transmission in a wavelength band including a complementary color component of a certain wavelength within a range of 550 nm to 600 nm and having a transmittance for light of a certain wavelength of less than 60% and in a range of 420 nm to 580 nm. The rate is in the range of 70% to 90%,
When the first image display element is controlled so that all of the illumination light for illuminating the first image display element is guided to the projection optical system, the light is guided from the first image display element to the projection optical system. When the second image display element is controlled so as to guide the light to be emitted to the first illumination light and all the illumination light to illuminate the second image display element to the projection optical system, the second image Controls the third image display element so that the light guided from the display element to the projection optical system is guided to the second illumination light, and all the illumination light that illuminates the third image display element is guided to the projection optical system. In this case, when the light guided from the third image display element to the projection optical system is the third illumination light,
The chromaticity coordinate in the white xy chromaticity diagram of an arbitrary point of the image projected on the projection surface is
0.28 ≦ x ≦ 0.34
0.29 ≦ y ≦ 0.36
To be within the range of
When performing a white display, the first image display element, the light intensity of the first image light guided from said first image display element to the projection optical system, 50% of the first amount of illumination light Adjusted to 95% or less,
When performing a white display, the second image display element, wherein a second of the second image light quantity of the image display element is guided to the projection optical system, 70% of the light quantity of the second illumination light Adjusted to 95% or less,
When performing a white display, the third image display element, the third a third quantity of image light guided from the image display element to the projection optical system, the third 90% of the light amount of the illumination light An image projection apparatus that is adjusted to be 100% or less.