JP2003066369A - Image display device, controlling method for image display device and image processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device, a controlling method for the image display device and an image processing system which have satisfactory color reproduction performance, whose configurations can be simplified without reducing light quantity that can be effectively utilized and whose cost can be reduced. SOLUTION: This image display device has a configuration in which three colors of RGB are respectively emitted from different light sources and expandingly projects, by an image forming means, a beam that simultaneously illuminates almost the entire display area of a transmission type or reflection type image displaying means with the respective light sources.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, an image display device control method, and an image processing system.

[0002]

2. Description of the Related Art Conventionally, as an image projection apparatus, a liquid crystal projector using a liquid crystal panel or a micromirror device (DMD,
There is also a projector using a reflection type image display device called digital light processing, DLP). These are the CRT display results of personal computers,
It is used for the purpose of projecting other digital images such as movies on the screen and observing many people at the same time.

In these, a light source generally belonging to a white lamp such as a metal halide lamp or a xenon discharge lamp has been used. Then, the luminous flux of the light source is condensed using a reflecting mirror, a lens, etc., and the liquid crystal or D
By illuminating an image display device such as an MD and transmitting or reflecting the device, the illumination light flux that is two-dimensionally modulated according to the image information displayed on the device is projected onto a screen by a projection lens. The configuration has been adopted.

For example, in the case of a general structure of a three-plate type liquid crystal projector using a liquid crystal panel, a light source luminous flux is amplitude-divided into three luminous flux components of RGB by a dichroic mirror or the like, and the three luminous fluxes of RGB are respectively divided. The three transmissive monochrome liquid crystal panels displaying image information are illuminated. An image of RGB three colors formed by the transmitted light flux is combined using a dichroic mirror or a dichroic prism, and the superimposed color image is projected by a projection lens.

Further, Japanese Patent No. 2704581 or Japanese Patent No. 3004524 discloses an example in which a laser is used as a light source of three colors. The former is to mix the light fluxes from the gas laser light sources of RGB three colors coaxially and then illuminate one liquid crystal panel to project it. By attaching an external intensity modulation element to each of the three color lasers, RGB is time-divided. Is to be projected by. In the latter, a gas laser or a semiconductor laser of three colors is used as a light source, and a screen using a phosphor is raster-scanned to display an image like a television.

[0006]

By the way, in the one described in the above-mentioned Japanese Patent No. 2704581, a large-scale apparatus is required because a gas laser is used. Further, in the one described in Japanese Patent No. 3004524, a two-dimensional image display panel is not required, but since it is premised on raster scanning, a scanning device therefor and a phosphor screen having an afterimage effect are essential.

On the other hand, in the case of a projector using a liquid crystal panel, the liquid crystal panel used is generally of the type utilizing polarized light such as TN liquid crystal. Therefore, when the liquid crystal panel is directly irradiated with the light source luminous flux having a random polarization direction from the above-mentioned light source, the polarization component in the direction not passing through the polarizing plate is absorbed, and as a result, about half the amount of light is absorbed and lost. Therefore, in general, there is a demand to obtain a projection image that is as bright as possible, but since the utilization efficiency of the light source light amount is low and there is a lot of waste, the light source must be made very bright. In addition, the energy of the polarized component in the unusable direction, which is absorbed by the polarizing plate, is converted into heat, so that a very large amount of heat is generated. as a result,
This will affect the life of the device and thus the device.

For this reason, conventionally, a light beam having a random polarization direction of the light source is subjected to polarization conversion operation, and the random polarization direction of the light beam of the light source is converted into one polarization direction with as little loss as possible by absorption. It is common to have a polarization conversion optical system that aligns the two. However, even when using a polarization conversion element for aligning the polarization direction of illumination light in one direction, precision processing technology and complicated steps are required to manufacture a polarization prism with a complicated structure. ,
There is also a component cost.

The light source generally emits white light, but when the spectrum of the emitted light beam is examined, it usually has a somewhat uniform energy distribution in the entire visible range. In addition, depending on the type of lamp, in addition to that, there are many cases in which some emission line spectrum is partially included. As described above, such light source luminous flux is RG
In the case of separating into three colors of B, the light is dispersed by reflection / transmission with a multilayer film such as a dichroic mirror. At this time, since the light source has a wide spectrum, the characteristics of the dichroic film are required to be correct so as to divide the three RGB bands. Especially, in the vicinity of the boundary of each color of RGB, a sharp rise / or fall without crossover as much as possible and a wavelength band for transmitting / reflecting a predetermined color light as high / low as possible are required to have flat characteristics.
The design and manufacture of dichroic coating film is very strict. In addition, the phase change due to the film must be uniformly small, and the incident angle must be small. Therefore, such a color separation / synthesis type optical component has many factors such as high cost, such as strict control of film thickness manufacturing accuracy and a large number of film constituents.

Although the three RGB colors are used, the respective colors are cut out from the luminous flux emitted from the white light source having the substantially uniform spectral spectrum distribution as described above according to the characteristics of the dichroic coat. Therefore, each of the three color lights of RGB is composed of a spectral spectrum distribution having a certain width. For this reason, the color purity is not so high, and there are some areas that are insufficient in color reproduction performance as compared with the RGB single colors. On the other hand, when the characteristics of the dichroic coating film are narrowed to extract more monochromatic color light, the most difficult problem is that the amount of light that can be effectively used will decrease again, although it is difficult to design the film. .

Therefore, the present invention solves the above-mentioned problems, has good color reproduction performance, does not reduce the amount of light that can be effectively used, and can simplify the configuration or reduce the cost of image display. An object of the present invention is to provide an apparatus, a method for controlling an image display device, and an image processing system.

[0012]

In order to achieve the above object, the present invention provides an image display device, an image display device control method, and an image processing system configured as described in (1) to (32) below. It is provided. (1) R, G, and B image display elements are illuminated with light from a plurality of light sources separately provided for R, G, and B, and the image display elements are illuminated from the light sources. An image display device which modulates the light to display an image, wherein the light source is a semiconductor laser. (2) The image display device according to (1), wherein the light from the light source illuminates the image display element via an anamorphic optical system. (3) The light from the light source is a luminous flux having a substantially elliptical intensity distribution, and the anamorphic optical system is configured to convert the luminous flux from the light source into a substantially isotropic intensity distribution. The image display device according to (2) above. (4) The image display device according to the above (2) or (3), wherein the anamorphic optical system has a wedge-shaped prism. (5) The image display device according to any one of (2) to (4), wherein the anamorphic optical system includes a cylinder lens. (6) The image display device according to any one of (2) to (5), wherein the anamorphic optical system includes a toric lens. (7) Any of the above (1) to (6), wherein the light from the light source illuminates the image display element through a collimator optical system that converts a divergent light flux from the light source into a substantially parallel light flux. An image display device according to claim 2. (8) The image display device according to (7), wherein the collimator optical system has a collimator lens having a positive refractive power. (9) The light from the light source is a constraint having a substantially elliptical intensity distribution, and the collimator optical system has means for cutting out the light from the light source into a substantially circular shape (7) or (8) The image display device according to the above. (10) The light from the light source is a divergent light flux having a substantially elliptical intensity distribution, and the light source has a collimator optical system that converts the light from the light source into substantially parallel light and cuts out into a substantially circular shape. The image display device according to (1). (11) The light from the light source is a divergent light flux having a substantially elliptical intensity distribution, and a collimating optical system that converts the light from the light source into substantially parallel light, and a substantially elliptical intensity from the collimating optical system. The image display device according to (1) above, further comprising an anamorphic optical system that converts light having a distribution into a substantially circular intensity distribution. (12) At least two of the plurality of light sources are semiconductor lasers having substantially the same oscillation wavelength, and the light from the at least two semiconductor lasers illuminates the same image display element. The image display device according to any one of 1) to 11). (13) The image display device according to the above (12), characterized in that the image display device has a conversion means for converting light from the at least two semiconductor lasers into light beams substantially parallel to each other. (14) The image display device according to the above (13), wherein the conversion means has a prism. (15) The image display device according to the above (13), wherein the conversion means is an optical system having a negative refractive power. (16) The image display device according to any one of the above (13) to (15), which has a means for compressing the substantially parallel light flux. (17) The above-mentioned (13) to (16), wherein the diffused light fluxes from the at least two semiconductor lasers enter the conversion means in a state where at least some of the plurality of diffused light fluxes overlap each other. The image display device according to any one of claims. (18) The image according to any one of (1) to (17) above, wherein the wavelength bands of light emitted by the R light source, the G light source, and the B light source do not overlap with each other. Display device. (19) The wavelength bands of light emitted by the R light source, the G light source, and the B light source are at least 10 each other.
The image display device according to (18) above, wherein the image display devices are separated by a distance of at least nm. (20) The image display device according to any one of (1) to (19), wherein the image display device is a liquid crystal display device. (21) The above-mentioned (1) to (2), characterized in that it has means for synthesizing image light from the plurality of image display elements.
0) The image display device according to any one of the above. (22) The image display device according to any one of (1) to (21), further comprising a projection unit that projects image light from the plurality of image display elements onto a projection surface. (23) In the image display device according to any one of (1) to (22), the color balance of the image displayed by the image display device is detected, and the R, G, and B colors are detected based on the detection result. A method for controlling an image display device, which comprises individually controlling the amount of light of a light source for a display. (24) When the color balance of an image displayed by the image display device is biased to a specific dominant color component, the light amount of a light source of a color component other than the dominant color component is reduced. (23) The method for controlling an image display device according to the above. (25) When the color balance of the image displayed by the image display device is biased to a specific dominant color component, the adjustment by controlling the light amount of the light source has priority over the color adjustment by the image display element. The method for controlling an image display device according to (23) or (24) above. (26) By controlling the light amount of the light source of each color,
The method for controlling an image display device according to any one of (23) to (25) above, wherein color reproducibility is emphasized or improved. (27) In the image display device according to any one of (1) to (22) above, the brightness of a display image displayed by the image display device is detected, and the R based on the detection result.
A method for controlling an image display device, characterized in that the light amount of each of the light sources for G, G, and B is increased or decreased substantially equally. (28) Based on the detection result of the brightness of the display image,
When adjusting the light quantity of the light source of each color, the adjustment by controlling the light quantity of the light source is prioritized over the adjustment by the image display element. . (29) When the brightness of the display image is bright, the light amounts of the light sources of the respective colors are increased substantially, and when the brightness of the display image is dark, the light amounts of the light sources of the respective colors are decreased by substantially the same amount. 27) or the method of controlling the image display device according to (28). (30) Based on the detection result of the brightness of the display image,
By controlling the light amount of the light source of each color to be substantially equal,
The method for controlling an image display device according to any one of (26) to (29), characterized in that the dynamic range is enhanced and improved when the display image is bright and dark. (31) An image processing device comprising the image display device according to any one of (1) to (22) above and an image information supply device for supplying image information to the image display device. (32) An image processing system comprising the image display device according to any one of (1) to (22) above and an image information supply device for supplying image information to the image display device.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiments of the present invention,
By applying the above configuration, for example, one side of the polarizing plate of the liquid crystal panel can be eliminated. Also,
The polarization direction of the incident light beam to the cross dichroic prism that synthesizes three colors is set to 90 around the optical axis of the corresponding semiconductor laser light source.
It can be freely set only by arranging it to rotate once, and an expensive half-wave plate can be eliminated. Further, since the color of the light source is close to monochromatic light, the accuracy of the film characteristics of the dichroic mirror is relaxed, and the design and manufacturing can be easily performed. Also, since the color of the light source is close to monochromatic light, the color purity is high,
Color reproducibility can be improved. In addition, since the semiconductor laser can easily modulate the intensity, it is possible to arbitrarily emphasize the color balance of the image by individually modulating the lasers of the three colors of RGB in accordance with the algorithm in consideration of the color balance of the image signal.

Further, in the case of an image in which the entire screen tends to a specific color tendency, if the complementary color light component to be reduced at the time of color reproduction is shielded / dimmed only by the liquid crystal panel, the leakage component due to the low contrast ratio of the liquid crystal. However, the color reproducibility is impaired, but according to this configuration, the color reproduction purity can be improved by narrowing the light source light amount itself of the color. Further, since the intensity modulation of the semiconductor laser is easy, the three-color lasers of RGB three colors are simultaneously modulated according to an algorithm that takes into consideration the temporal change of the brightness of the entire screen of the image signal, so that the temporal dynamic range of the image contrast is increased. It becomes possible to emphasize. Further, in the past, in a dark image, most of the density variable range of the liquid crystal is used to reduce the total amount of light, so the remaining density variable range that can be used for gradation display of a display object in the dark is reduced. As a result, the gradation image in the dark has less gradation and tends to be crushed. According to the present configuration, by using the light amount control for darkening itself, there is sufficient room for gradation expression, so that a good image display that does not collapse even in darkness is possible. In addition, black floating can be reduced, and when the liquid crystal blocks most of the light, there is concern that absorption of the polarizing plate may affect the heat generation and durability of each part of the device. If so, these points can be improved.

As described above, the image display device of this configuration has
Semiconductor lasers (including those using SHG) are used as the light source, but in recent years, semiconductor lasers capable of oscillating two colors of blue and green respectively have been developed. Blue semiconductor lasers are also about to be increased in output. In the case of red, which has been used conventionally, the output has been increased, for example, several hundreds
Higher output has advanced up to the mW class, and there is a possibility that the output will eventually reach the range of several W. In addition, the brightness of the data projector is evaluated by a luminous flux [lm] (lumen), and a product of about 300 to 2000 [ANSI lumen] is distributed according to a luminous flux evaluation rule called a so-called ANSI lumen.

When a semiconductor laser is used as a light source,
For example, how much light output [W] is required for green 555 [nm] is roughly estimated. Luminous flux as photometric quantity: F [lm] Maximum luminous efficiency: Km = 680 [lm / W] Specific luminous efficiency at 555 [nm]: V (λ) ≈1.0
[No unit] When all the power of the laser output projected on the screen is Pλ [W], since it is a laser light source, the spectrum can be regarded as almost a single wavelength. There is. F = Km × V (λ) × Pλ Therefore, it is assumed that the green luminous flux of 555 [nm] is 200
If [lm] is required, then Pλ≈300 [mW], and if a light flux of about three colors of RGB can be obtained, it is about 600.
Lumen brightness is obtained and reaches practical level. For red and blue, the relative luminosity factor V (λ) is much lower than that for green, and thus requires more power than in the case of the above green, but this point also leads to further higher output of the semiconductor laser in the future. It is possible to solve the problem by combining a plurality of lasers with.

[0017]

EXAMPLES Examples of the present invention will be described below. [Embodiment 1] FIG. 1A shows the configuration of an image projection apparatus according to Embodiment 1 of the present invention. A diffused light flux from the semiconductor laser is converted into a substantially parallel light flux by a collimator lens, and the liquid crystal panel is irradiated with the light flux. In the present embodiment, this configuration has RGB
Three colors are prepared, and the light fluxes passing through the respective liquid crystal panels are combined by an ordinary dichroic prism and projected on a screen by a projection lens.

As is well known, as shown in FIG. 1B, the distribution of the emitted light of the semiconductor laser is generally elliptical. PN junction surface of semiconductor laser chip,
That is, the emission angle is large in the direction perpendicular to the active layer, and the emission angle is narrow in the direction parallel to the active layer. Further, the position of the virtual light emitting point in the chip is different in the optical axis direction between the vertical direction and the parallel direction, and the vertical direction is parallel to the end face as viewed from the chip end. The direction is at the back. That is, the emitted light of the semiconductor laser has astigmatism, and therefore, when collimated by the collimator lens, the collimated light beam has an elliptical cross-sectional intensity distribution. Further, the focal position of the collimator lens is adjusted so as to be located near the middle of the astigmatic difference in the laser chip. Although the astigmatism remains even after the light is made substantially parallel, its influence can be reduced by adjusting as described above.

On the other hand, as shown in FIG. 1C, with respect to the elliptical light distribution, only the central portion is cut out by a collimator lens into, for example, a circular shape to make parallel light. Alternatively, a collimator lens having a large aperture is used which can convert the elliptical light flux into a substantially parallel light flux. In any case, since it is necessary to illuminate the entire surface of the liquid crystal panel with the substantially parallel light flux, a portion of the elliptical light distribution of the parallel laser light flux that can cover the panel area is used.

As shown in the figure, when a cross dichroic prism is used to combine the image light fluxes of the three colors of RGB, for example, in this example, the transmitted light flux is green, and blue and red are respectively from the side surfaces of the prism. One method is to introduce it, reflect it on the dichroic film, and synthesize it with the transmitted green color. At this time, the polarization direction of the green color is P polarization with respect to the dichroic mirror surface, and the red color and the blue color are S polarization, due to the conditions of the film structure. Therefore, the liquid crystal panel for the green image and the liquid crystal panels for the red and blue images need to be arranged so that the polarization directions of the display image and the prism are rotated by 90 degrees. Further, since the polarization direction of the light source also needs to be different by 90 degrees depending on the panel polarization direction, this can be achieved by only disposing the semiconductor laser twisted by 90 degrees around the optical axis. Therefore, as in the case of the conventional white light source, after the polarization directions are all aligned, the RGB light is separated into three colors, and when the panel is illuminated, the polarized light is polarized in accordance with the conditions such as the cross dichroic prism of the composite system. An advantage is that it is not necessary to use an expensive half-wave plate or the like corresponding to each color for rotating the direction by 90 degrees.

However, since other elements such as dichroic coat which influence the phase are arranged in the optical path, even if the linear polarization degree of the light source is high, those phase axes and the polarization plane of the laser are mechanically affected. It cannot be said that there is a factor that deteriorates the contrast, such as a component that is orthogonal to a predetermined linear polarization axis due to a slight inclination, or elliptically polarized light due to phase delay. In such a case, it must be considered that the quality of the entire image may be improved if the polarizing plate on one side of the liquid crystal is not omitted.

Further, since the oscillation wavelength of the semiconductor laser is almost a single wavelength in the case of single mode oscillation, it is a light having a very high monochromaticity, and even if it is used in a multimode oscillation state, it is white. Compared to the case where the light source is color-separated, the oscillation modes are concentrated in a much narrower wavelength band, which can almost be called monochromatic. Therefore,
The film characteristics of the dichroic mirror of the synthetic optical system and the wavelength range required to maintain uniform transmittance or reflectance compared to the case of using a white light source are also very narrow according to the laser oscillation wavelength. Therefore, the accuracy required for the design and manufacturing of the optical film is greatly relaxed.

In the case of a device using a white light source, since there is one light source and the light is separated into three colors, it is not possible to modulate the three color lights by the color before the panel illumination. Basically you can't. Also, it is difficult to modulate all three colors, that is, to modulate the brightness level of the entire screen in accordance with the image signal, at any speed because of the light emitting principle of the lamp. It is preferable to keep the lamp stably lit while keeping the brightness as constant as possible in order to use the lamp without imposing a load and shortening the life. Therefore, for the purpose of modulating the brightness of the entire light source, there is no choice but to separately provide a light control means such as a variable light-shielding plate.

On the other hand, in this embodiment, since the three RGB colors are different light sources, the intensity can be individually modulated. Also, since the light source is a semiconductor laser, very high speed intensity modulation is possible only by modulating the drive current. When the color tendency of the entire screen tends to a specific direction, or when an image is displayed in which a certain color and a black part that does not emit light are temporally replaced, each of the three RGB lasers is individually matched to the color. By changing the intensity, it is possible to emphasize the balance of the colors expressed on the screen. In addition, when there is a time in which the entire screen tends to be bright and a time in which the entire screen tends to be dark due to changes in the time axis direction of the image, intensity modulation is performed so that the light sources of the three colors RGB are simultaneously darkened or brightened. By applying
It is possible to expand the dynamic range of temporal changes in bright and dark scenes. This can also be easily executed at high speed by modulating the laser drive current according to the image. Further, as the laser output monitor, if the output of the rear monitor PD normally installed in the laser package is used, it is not necessary to provide a new configuration.

[Second Embodiment] FIG. 2 shows the arrangement of an image projection apparatus according to the second embodiment of the present invention. The oscillation light flux of a semiconductor laser has an elliptical intensity distribution. When collimating this as the illumination light flux for the panel as it is, the configuration is simple, but the shape of the light flux differs greatly from the shape of the light flux, and the utilization efficiency of the light quantity is large. Is not high. Therefore, in the present embodiment, the elliptical light flux once converted into a parallel light flux is made a more isotropic light flux by passing through the anamorphic beam shaping optical system,
It is possible to improve the utilization efficiency of illumination light and the uniformity of illumination on the screen.

The polarization direction of the semiconductor laser is parallel to the minor axis direction (θ // direction in FIG. 2) of the elliptical light quantity distribution shape. On the other hand, the requirement of the polarization direction at the time of incidence on the dichroic prism for combining light fluxes differs depending on the colors of RGB. For example, in many cases, green is P-polarized light because it is combined by transmission, and red and blue are S-polarized light because they are combined by reflection. However, the direction of the elliptical shape distribution is narrow with respect to the polarization direction as described above, so that the major axis of the elliptical light flux is reduced depending on the color.
Alternatively, it is possible to properly use a beam shaping optical system that expands the distribution in the short axis direction. In that case, it is necessary to adjust the focal length of the collimator lens so that the diameters of the parallel light beams that illuminate the panel are the same.

As shown in FIG. 2, a diffused light flux from a semiconductor laser is converted into a substantially parallel light flux by a collimator lens, and the light flux is obliquely incident on a wedge-shaped glass prism to expand the light flux width in the θ // direction. Then, a more isotropic parallel light flux can be extracted. The anamorphic optical system for beam shaping is not limited to the wedge prism, and may be a combination of cylinder lenses. As shown in the figure, the red and blue lasers have the conditions of the beam shaping direction and the incident polarization direction to the combining prism, so that the beam width can be expanded by arranging them in the plane of the paper as shown in FIG. .

On the other hand, the polarization direction of the green laser must be different from that of the other colors by 90 °. Therefore, when the wedge prism is used, it must be arranged in a direction projecting from the paper surface. In order to avoid this, it is possible to form an anamorphic beam shaping optical system by combining a cylindrical lens having only a green laser as shown in FIG. Here, the anamorphic optical system arranged in the optical path of each color of RGB may use a cylinder lens,
A wedge-shaped prism may be used, and one that is more suitable for the design of the optical path of each color may be used. Of course, a cylinder lens may be used in the optical paths of all colors, or a wedge-shaped prism may be used in the optical paths of all colors.

[Third Embodiment] FIG. 3 shows the configuration of a beam wave field combining system according to a third embodiment of the present invention. If the image brightness on the screen is insufficient with the output of one semiconductor laser for each color, it is possible to increase the amount of light by using a plurality of lasers for each color. Therefore, in this embodiment, one output of the semiconductor laser is being increased, but there is also a great demand for improving the brightness of the projected image. Therefore, by using a plurality of these, the arrangement of the optical system for increasing the light amount is arranged. And

In FIG. 3, the diffused light flux from the semiconductor laser is made into a parallel light flux by a collimator lens, and this is obliquely refracted and incident on a wedge prism. A plurality of these are arranged side by side in parallel to form a light beam with a large area in the form of wavefront coupling. If necessary, the combined luminous flux width and luminous flux diameter can be reduced again using a cylinder lens, a convex lens, a concave lens, a prism or the like to obtain a luminous flux with increased energy density.

[Embodiment 4] FIG. 4 shows a control method of an image projection apparatus in Embodiment 4 of the present invention. An algorithm that emphasizes the color expression of the projected image by individually intensity-modulating the RGB three-color light sources according to the color balance and tendency of the projected image is used.

Generally, when the image to be projected is, for example, a movie such as a movie in which green forests, trees, etc. are displayed on one side, the transmittance of the liquid crystal green panel is generally high and the The transmittance of the display panel is slightly lower than that of the panel for red, and the transmittance of the panel for red is particularly low as a whole. Thus, the color reproducibility is controlled only by the control of the transmittance of the liquid crystal panel.

On the other hand, in the case of the present invention, the following control is performed. In the case of controlling the transmittance of only the liquid crystal in the above example, the transmittance of the liquid crystal panel for red is sufficiently reduced while maintaining the emitted light amount of the red laser whose red light amount is to be reduced. However, since the contrast ratio of the liquid crystal panel is not so high, the red component is not shielded sufficiently and is mixed in the image light amount. As a result, the color purity of the green color reproduced is reduced, which is not preferable. Therefore, in the present embodiment, in such a case, the light output of the red semiconductor laser is reduced without reducing the transmittance of the red liquid crystal panel so much that the red light amount is controlled to be equal.

On the other hand, in the case of an image in which red is dominant such as the setting sky, the transmittance of the liquid crystal panel for green is not lowered as a whole, but the light output of the liquid crystal and the green semiconductor laser is reduced. It is possible to improve the color reproducibility by controlling in combination with lowering. These are evaluated based on the luminance signal of each of the three colors RGB and the number of display pixels to determine whether the area of a specific color is dominant by evaluating immediately before displaying the color signal of the image to be displayed. It is realized by sending a control signal to the lighting current.

[Embodiment 5] FIGS. 5 and 6 are views for explaining Embodiment 5 of the present invention. An algorithm is used that emphasizes the luminance expression of the projected image by intensity-modulating the light sources of the three colors of RGB in intensity in accordance with the brightness as the white level of the projected image. Images projected from the past are images such as movies, and generally there is not much color bias,
In the case where the light is bright on one side and the case where the night view is dark as a whole, the transmittances of the liquid crystal panels of all the three RGB colors are usually expressed by controlling them to be substantially equal, except for a slight difference between the colors. In a dark scene or the like, due to the low contrast ratio of the liquid crystal panel, black is not sufficiently darkened due to insufficient light shielding, and a so-called black floating state becomes a whitish black state, which is not preferable in expression. In addition, for a scene in the dark such as a night view, some kind of image expression must be performed in the dark. However, in this case, most of the original gradation expression range of the liquid crystal is used to darken the entire screen, and the remaining density range is narrowed (less) to perform some gradation expression in the dark. After that, I was only able to express what was called a collapse.

Therefore, in the case of this embodiment, the following control is performed. When the entire screen is dark such as a night view, the transmittance of the liquid crystal panel is not reduced to be almost the same for all RGB, but the liquid crystal panel uses its variable transmittance range (density range) sufficiently for gradation expression. Thus, the darkness of the screen itself will be expressed by reducing the amount of light from the light source. As a result, the reproducibility of black is improved, the so-called black tightness is improved, and the dynamic range of the temporal contrast of the image is expanded. Further, regarding gradation expression in a dark screen, the original gradation expression range of the liquid crystal can be used more effectively, so gradation characteristics are not impaired even in a dark screen, and reproducibility is improved without being crushed even in a dark screen. .

The effect of this embodiment is shown in FIG. If the histogram of the original image shows that this is a dark image, expand the brightness of the brightest pixel in the image to near the upper limit of the displayable gradation range, and reduce the light source light amount according to that ratio. Then, since the finally obtained image is the product of them, the brightness is equivalent. However, since the expressible gradation is effectively using the original gradation, it is possible to prevent the loss of fine density changes.
The actual operation is executed according to the algorithm shown in FIG. In addition, the image display device described in the above embodiment is an image processing device by incorporating an image information supply device (video, DVD, personal computer or the like) for supplying image information,
Alternatively, it can be applied to an image processing system.

[0038]

As described above, according to the present invention, the color reproduction performance is good, and the amount of light that can be effectively used is not reduced, and the configuration can be simplified or the cost can be reduced. An image display device, a method for controlling the image display device, and an image processing system can be realized.

[Brief description of drawings]

FIG. 1A is a diagram showing a configuration of an image projection apparatus according to a first embodiment of the present invention. (B) is a figure for demonstrating a semiconductor laser light distribution characteristic, (c) is a figure for demonstrating a laser light distribution and a panel.

FIG. 2 is a diagram showing a configuration of an image projection device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a beam wave field synthesis system according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a control method of the image projection apparatus in Embodiment 4 of the present invention.

FIG. 5 is a diagram for explaining a fifth embodiment of the present invention.

FIG. 6 is a diagram for explaining a fifth embodiment of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13357 G03B 21/00 E G03B 21/00 21/14 A 21/14 H01S 5/40 H01S 5 / 40 H04N 9/31 C H04N 9/31 G02B 27/00 EF term (reference) 2H088 EA12 HA13 HA14 HA18 HA23 HA24 HA28 MA20 2H091 FA05X FA08X FA08Z FA21X FA28X FA34X FA41Z LA30 MA07 2H093 NC42 NC53 ND54 C060 BC0502 HD00 JA00 JB06 5F073 AB27 BA09 EA02 EA22 GA02

Claims (32)

[Claims] 1. R, G, and B image display elements are illuminated with light from a plurality of light sources separately provided for R, G, and B, and each of the image display elements is used for illuminating. An image display device for modulating light from a light source to display an image, wherein the light source is a semiconductor laser. 2. The image display device according to claim 1, wherein the light from the light source illuminates the image display element through an anamorphic optical system. 3. The light from the light source is a luminous flux having a substantially elliptical intensity distribution, and the anamorphic optical system is configured to convert the luminous flux from the light source into a substantially isotropic intensity distribution. The image display device according to claim 2, wherein 4. The image display device according to claim 2, wherein the anamorphic optical system has a wedge-shaped prism. 5. The image display device according to claim 2, wherein the anamorphic optical system includes a cylinder lens. 6. The image display device according to claim 2, wherein the anamorphic optical system includes a toric lens. 7. The light from the light source illuminates the image display element through a collimator optical system that converts a divergent light beam from the light source into a substantially parallel light beam. The image display device according to item 1. 8. The image display device according to claim 7, wherein the collimator optical system has a collimator lens having a positive refractive power. 9. The light from the light source is a constraint having a substantially elliptical intensity distribution, and the collimator optical system has means for cutting out the light from the light source into a substantially circular shape. Alternatively, the image display device according to item 8. 10. A collimator optical system in which the light from the light source is a divergent light flux having a substantially elliptical intensity distribution, and the light from the light source is converted into substantially parallel light and cut into a substantially circular shape. The image display device according to claim 1. 11. A collimating optical system for converting light from the light source into substantially parallel light, wherein the light from the light source is a divergent light flux having a substantially elliptical intensity distribution, and a substantially elliptical shape from the collimating optical system. 2. An image display device according to claim 1, further comprising: an anamorphic optical system that converts light having the intensity distribution of 1 to an intensity distribution of a substantially circular shape. 12. A semiconductor laser in which at least two of the plurality of light sources have substantially the same oscillation wavelength, and the light from the at least two semiconductor lasers illuminates the same image display element. The image display device according to claim 1. 13. The image display device according to claim 12, further comprising a conversion unit that converts light from the at least two semiconductor lasers into light beams substantially parallel to each other. 14. The image display device according to claim 13, wherein the conversion means has a prism. 15. The image display device according to claim 13, wherein the conversion means is an optical system having a negative refractive power. 16. The image display device according to claim 13, further comprising means for compressing the substantially parallel light flux. 17. The diffused light fluxes from the at least two semiconductor lasers are incident on the conversion means in a state where at least some of the plurality of diffused light fluxes overlap each other. The image display device according to item 1. 18. The image according to claim 1, wherein the wavelength bands of light emitted by the R light source, the G light source, and the B light source do not overlap with each other. Display device. 19. The light source for R, the light source for G, and the light source for B respectively emit light in wavelength bands separated from each other by at least 10 nm or more. 18. The image display device according to item 18. 20. The image display device according to claim 1, wherein the image display element is a liquid crystal display element. 21. A means for synthesizing image light from the plurality of image display elements, wherein:
0. The image display device according to any one of items. 22. The image display device according to claim 1, further comprising a projection unit that projects image light from the plurality of image display elements onto a projection surface. 23. The image display device according to claim 1, wherein the color balance of the image displayed by the image display device is detected, and the R, G, and A method for controlling an image display device, wherein the light amount of a light source for B is individually controlled. 24. When the color balance of an image displayed by the image display device is biased to a specific dominant color component,
24. The method of controlling an image display device according to claim 23, wherein the light amount of a light source of a color component other than the dominant color component is reduced. 25. When the color balance of an image displayed by the image display device is biased to a specific dominant color component,
25. The control method of the image display device according to claim 23, wherein the adjustment by controlling the light amount of the light source is prioritized over the color adjustment by the image display element. 26. A method of controlling an image display device according to claim 23, wherein the color reproducibility is emphasized or improved by controlling the light quantity of the light source of each color. . 27. The image display device according to claim 1, wherein the brightness of a display image displayed by the image display device is detected, and based on the detection result, the R and G images are detected. , A method for controlling an image display device, wherein the light amounts of the light sources for B and B are increased and decreased in a substantially equal manner. 28. When adjusting the light amount of the light source of each color based on the detection result of the brightness of the display image, the adjustment by controlling the light amount of the light source is prioritized over the adjustment by the image display element. 28.
A method for controlling the image display device described. 29. When the brightness of the display image is bright, the light amounts of the light sources of the respective colors are increased substantially equally, and when the brightness of the display image is dark, the light amounts of the light sources of the respective colors are reduced substantially the same. A method for controlling an image display device according to claim 27 or 28. 30. Based on the detection result of the brightness of the display image, the light amounts of the light sources of the respective colors are controlled to be substantially equal, thereby enhancing and improving the dynamic range when the display image is bright and dark. 2. The method according to claim 2, wherein
30. The method for controlling the image display device according to any one of 6 to 29. 31. An image processing apparatus, comprising: the image display apparatus according to claim 1; and an image information supply apparatus for supplying image information to the image display apparatus. 32. An image processing system, comprising: the image display device according to claim 1; and an image information supply device for supplying image information to the image display device.