JP4061940B2 - Image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display device that projects and displays an image according to image information on a screen.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image display device called a “front projector” has been proposed as an image display device that can easily enjoy a large screen image.
[0003]
Such an image display device includes a three-tube cathode ray tube (CRT) that displays an R (red) component, a G (green) component, and a B (blue) component of an image, and displays these cathode ray tubes. A configuration is proposed in which images to be overlapped through an R (red) filter, a G (green) filter, and a B (blue) filter, respectively, and projected onto the screen from the front side. However, such a “three-tube CRT type” image display device is mainly used for business use because it has a large and heavy device configuration, is difficult to set, and is expensive. Is not very popular.
[0004]
In recent years, a “front projector” type image display device using a liquid crystal display panel instead of a cathode ray tube has been proposed. This image display device can be reduced in size and weight compared to the one equipped with a cathode ray tube, can be set easily, and can be reduced in price. It is also expected to spread for household use.
[0005]
Furthermore, as a light source in this image display device, laser light has features such as high light collection efficiency with respect to a liquid crystal display panel, a wide color reproduction range, and good focus characteristics, and is considered to be very suitable light.
[0006]
[Problems to be solved by the invention]
As a light source in the image display apparatus as described above, it is necessary to align all three colors of red (R), green (G), and blue (B) laser beams. However, it is difficult to obtain laser beams of three colors of red (R), green (G), and blue (B), and it is difficult to reduce the size and weight of the device and to reduce the cost. It has not reached practical use.
[0007]
That is, although a blue (B) semiconductor laser has been developed, its emission wavelength is 400 nm to 410 nm, and the visibility as a blue light source is poor, and the efficiency as a light source of an image display device is extremely poor. . In order to use it as a blue light source, it is necessary to increase the wavelength to around 450 nm.
[0008]
As for the green (G) laser, solid-state lasers have made remarkable progress in the medical field, but semiconductor lasers have been very late. Laser development based on ZnSe has been carried out. At present, a method of doping In to blue GaN is considered to be mainstream, but there is no plan for practical use.
[0009]
The red high-power semiconductor laser has already been commercialized with an emission wavelength of 647 nm (3 W), and although there are few technical problems, there are still problems in reducing cost and increasing reliability. Remaining.
[0010]
In view of the above circumstances, the present invention realizes a reduction in the size and weight of the apparatus and a reduction in cost, and uses a laser light source for all three colors of red (R), green (G), and blue (B). It is an object of the present invention to provide an image display device that uses it to display a color image.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problem, an image display device according to the present invention includes a laser light source that emits light of two colors among the three primary colors of red, green, and blue, an excitation light source laser that emits excitation light, and these laser light sources, Spatial light modulation means for modulating the intensity of the light beam emitted from the excitation light source laser according to image information, and the wavelength of the excitation light excited by the excitation light and converted to the remaining one of the three primary colors, and emitted from the laser light source. A screen having, on the projection surface, a fluorescent material that is not excited by light of two colors among the three primary colors, and a projection unit that projects the two primary color light and excitation light intensity-modulated by the spatial light modulation unit on the screen, The screen reflects the two primary color lights projected by the projection means, converts the excitation light projected by the projection means to the remaining one of the three primary colors, and releases it. It is characterized in that.
[0012]
In this image display device, light of one of the three primary colors is radiated from the screen by wavelength conversion from the excitation light on the screen, so that the allowable range of the wavelength of the excitation light can be widened.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0014]
As shown in FIG. 1, the image display apparatus according to the present invention includes two elements: a projector 1 that projects an image, and a screen 2 that projects the image. The projector 1 includes a laser light source that emits visible laser light of two colors of the three primary colors of red (R), green (G), and blue (B), and an excitation light source laser that emits ultraviolet laser light that serves as excitation light. It is configured. The screen 2 includes a fluorescent material that converts ultraviolet light into the remaining one of the three primary colors on the front image projection surface.
[0015]
The projector 1 includes first and second visible light lasers 3 and 4 constituting a laser light source, and an ultraviolet light laser 5 serving as an excitation light source laser. Each of the laser beams emitted from the first and second visible light lasers 3 and 4 and the ultraviolet laser 5 is incident on the cross dichroic prism 6 and synthesized, and passes through a projection lens unit 7 serving as a projecting unit, and then the screen. 2 is projected on.
[0016]
In the projector 1, each laser beam is intensity-modulated according to image information for each color by a control circuit (not shown) serving as a spatial light modulator, and forms an image on the screen 2. The projection direction is scanned.
[0017]
As the spatial light modulation means, each laser beam is incident, and a reflection type or transmission type liquid crystal modulation element that modulates the intensity of each laser beam for each color according to image information, or a switching element such as a micromirror array Can also be used.
[0018]
That is, the projector 1 projects the image of the first primary color component of the image to be displayed on the screen 2 by the first primary color light, and the image of the second primary color component of the image to be displayed is the second. The image of the third primary color component of the image to be displayed is projected onto the screen 2 with the primary color light and projected onto the screen 2 with the ultraviolet light, and these are superimposed.
[0019]
In this image display device, the laser light projected from the projector 1 is a red (R) laser beam from a semiconductor laser and a green (G) laser from a solid state laser as shown in FIG. Light and ultraviolet laser light from an ultraviolet semiconductor laser. When these laser beams are projected onto the screen 2, as shown in FIG. 2B, a fluorescent material applied to the projection surface of the screen 2, such as Sr ₁₀ (PO ₄ ) ₆ Cl. ₂ : The wavelength of ultraviolet laser light of 410 nm is converted into blue (B) light around 450 nm by Eu and emitted from the screen 2. Since the red (R) and green (G) laser beams are reflected as they are on the screen 2, the red (R), green (G), and blue (B) lights are combined and emitted from the screen 2. As a result, a full-color image is displayed.
[0020]
Note that Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu, which is a fluorescent material, is hardly excited by red (R) and green (G) light.
[0021]
In addition, as shown in FIG. 3A, this image display device projects red (R) and blue (B) light from a semiconductor laser and ultraviolet laser light from a semiconductor laser. The ultraviolet laser light projected from the semiconductor laser can be configured to be wavelength-converted to green (G) on the screen 2 as shown in FIG.
[0022]
In this case, the wavelength of the 410 nm ultraviolet laser beam is converted into green (G) light around 530 nm by a fluorescent material applied to the projection surface of the screen 2, for example, ZnS; Cu, Al. Radiated. Since the red (R) and blue (B) laser lights are reflected as they are on the screen 2, the red (R), green (G) and blue (B) lights are combined and emitted from the screen 2. As a result, a full-color image is displayed.
[0023]
In addition, ZnS; Cu, Al which is a fluorescent substance is hardly excited by red (R) and blue (B) light.
[0024]
Further, as shown in FIG. 4A, this image display device projects blue (B) light from a semiconductor laser, green (G) light from a solid laser, and ultraviolet laser light. Is projected from the semiconductor laser, and the ultraviolet laser light projected from the semiconductor laser is wavelength-converted to red (R) on the screen 2 as shown in FIG. 4B. You can also.
[0025]
In this case, the 410 nm ultraviolet laser light is wavelength-converted into red (R) light around 650 nm and emitted from the screen 2 by the fluorescent material applied to the projection surface of the screen 2. Since the blue (B) and green (G) laser beams are reflected as they are on the screen 2, the red (R), green (G) and blue (B) lights are combined and emitted from the screen 2. As a result, a full-color image is displayed.
[0026]
Note that the fluorescent material applied to the projection surface of the screen 2 is hardly excited by blue (B) and green (G) light.
[0027]
In this way, in this image display device, as shown in FIG. 5, the screen 2 has red (R) (wavelength near 650 nm), green (G) (wavelength near 530 nm), and blue (B) (wavelength). Three types of light (around 450 nm) are emitted, and a full-color image display is performed. In this image display device, such three types of light are emitted, whereby satisfactory color reproduction can be performed as shown in the chromaticity diagram characteristics of FIG.
[0028]
As described above, a semiconductor laser can be used for red (R) light, a solid-state laser can be used for green (G) light, and an ultraviolet laser for exciting a fluorescent substance on a screen has an emission wavelength of 410 nm. A semiconductor laser can be used. More specifically, as a red (R) laser, a semiconductor laser with an emission wavelength of 647 nm (3 W) is used, and from a US “SDL”, a green (G) laser has an emission wavelength of 532 nm (−10 W). Solid-state lasers have been commercialized by “Coherent” and others, and as blue (B) light lasers, solid-state lasers having an emission wavelength of 457 nm (400 mW) have been commercialized by “Melles Griot”. As an ultraviolet laser, a semiconductor laser having an emission wavelength of 400 nm to 420 nm has been recently developed.
[0029]
And the following points are mentioned as a characteristic required for the fluorescent substance on a screen. That is, it is excited by ultraviolet rays having a wavelength longer than 400 nm and emits predetermined color light (visible light) (in order to prevent crosstalk with other colors, the wavelength width of the emitted light is preferably narrow). They are not excited by other visible light lasers and have high conversion efficiency from excitation light to predetermined visible light.
[0030]
As a manufacturing method of the screen 2, a paste obtained by mixing a white pigment, a gain control agent, a binder, and the like with an ultraviolet excitation type fluorescent substance is used, as shown in FIG. Or the method of apply | coating on the base sheet 9 and forming the fluorescent substance layer 10 using another coating method is mentioned. As described above, “Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu”, “ZnS; Cu, Al” or the like is used as the fluorescent material.
[0031]
Alternatively, as shown in FIG. 8, the screen 2 can also be manufactured by a method of kneading a fluorescent material into the base sheet material when the base sheet 9 itself is created. In this case, while the base sheet material 9 is pulled out from the supply roller 13 and taken up by the take-up roller 14, the paste containing the fluorescent material is kneaded by the doctor blade 11 and dried by the dryer 12. Then, the fluorescent material layer 10 is formed.
[0032]
As shown in FIG. 9, the screen 2 manufactured in this way is in a state in which the fluorescent material layer 10 is attached to the front surface of the base sheet 9.
[0033]
In the image display apparatus according to the present invention having the above-described configuration, for example, it is possible to realize a “full-color laser display system” in which the total white luminance on the screen 2 is about 300 lm (lumen).
[0034]
【The invention's effect】
As described above, in the image display device according to the present invention, light of one of the three primary colors is radiated from the screen by wavelength conversion from the excitation light on the screen, so that the allowable range of the wavelength of the excitation light is widened. can do.
[0035]
Therefore, in this image display device, full-color image display is possible even when all three color laser light sources of red (R) light, green (G) light, and blue (B) light cannot be prepared.
[0036]
That is, by using a semiconductor laser for red (R) light and a solid-state laser for green (G) light, full-color image display is possible without using a blue (B) light laser having an emission wavelength of about 450 nm.
[0037]
If a semiconductor laser that emits blue (B) light can be used, it can be used in combination with a semiconductor laser that emits red (R) light and a semiconductor laser that emits excitation light (ultraviolet light). The light source can be a semiconductor laser. As described above, by using a semiconductor laser or a solid-state laser, it is possible to reduce the size of the apparatus and improve the utilization efficiency of illumination light.
[0038]
Furthermore, when a semiconductor laser that emits blue (B) light and a solid-state laser that emits green (G) light are used, the flexibility with respect to the laser that emits red (R) light increases, and the degree of design freedom increases.
[0039]
In this image display device, even if the speckle noise due to the laser is large, the speckle noise can be reduced (particularly, this effect is great for green (G) light).
[0040]
That is, the present invention displays a color image using a laser light source for all three colors of red (R), green (G), and blue (B) while realizing a reduction in size and weight and cost of the apparatus. An image display device can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of an image display device according to the present invention.
FIG. 2 is a graph (A) showing the wavelength characteristics of the projection light from the projector of the image display device and a graph (B) showing the wavelength characteristics of the light emitted from the screen 2;
FIG. 3 is a graph (A) showing another form of wavelength characteristics of light projected from the projector of the image display device and a graph (B) showing wavelength characteristics of light emitted from the screen 2;
FIG. 4 is a graph (A) showing still another form of wavelength characteristics of projection light from the projector of the image display device and a graph (B) showing wavelength characteristics of light emitted from the screen 2;
FIG. 5 is a graph showing wavelength characteristics of projection light from a projector of the image display device.
FIG. 6 is a chromaticity diagram showing color reproduction characteristics in the image display device.
FIG. 7 is a side view showing a method for manufacturing a screen in the image display device.
FIG. 8 is a side view showing another embodiment of a method for manufacturing a screen in the image display device.
FIG. 9 is a longitudinal sectional view showing a configuration of a screen in the image display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Projector 2 Screen 3 1st visible light laser 4 2nd visible light laser 5 Ultraviolet light laser 9 Base sheet 10 Fluorescent substance layer

Claims (5)

A laser light source that emits light of two colors of the three primary colors red, green and blue;
An excitation light source laser that emits excitation light;
Spatial light modulation means for modulating the intensity of light beams emitted from the laser light source and the excitation light source laser according to image information;
Excited by the excitation light, wavelength-converts the excitation light to the remaining one of the three primary colors, and has a fluorescent material on the projection plane that is not excited by light of the two primary colors emitted from the laser light source. Screen,
Projecting means for projecting the primary color light and excitation light intensity-modulated by the spatial light modulation means onto the screen;
The image is characterized in that the screen reflects the two primary color lights projected by the projection means and radiates the excitation light projected by the projection means after wavelength conversion to the remaining one of the three primary colors. Display device. The excitation light emitted from the excitation light source laser has a wavelength of 400 nm or more,
2. The image display apparatus according to claim 1, wherein the optical component constituting the projection means is designed for visible light. The laser light source includes a semiconductor laser that emits red laser light and a solid-state laser that emits green laser light.
The excitation light source laser is a semiconductor laser emitting ultraviolet light,
2. The image display device according to claim 1, wherein the fluorescent material that the screen has on the projection surface radiates the ultraviolet light by converting the wavelength of the ultraviolet light into blue light. The laser light source includes a semiconductor laser that emits red laser light and a semiconductor laser that emits blue laser light.
The excitation light source laser is a semiconductor laser emitting ultraviolet light,
The image display apparatus according to claim 1, wherein the fluorescent material that the screen has on the projection surface radiates the ultraviolet light by converting the wavelength of the ultraviolet light into green light. The laser light source comprises a solid state laser that emits green laser light and a semiconductor laser that emits blue laser light,
The excitation light source laser is a semiconductor laser emitting ultraviolet light,
The image display apparatus according to claim 1, wherein the fluorescent material that the screen has on the projection surface radiates the ultraviolet light by converting the wavelength of the ultraviolet light into red light.

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