JPH10293268A - Laser display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the compatibility of ensuring a sufficiently wide color reproducing range and obtaining a sufficient output with ease. SOLUTION: A light beam transmitted from a light source device 11 is made to be a parallel light beam by a collimator lens 12, deflected by a light deflector 13, a fly-eye lens array 14 is irradiated with the beam and a secondary light source train is formed. Each light beam from the secondary light source train is made to be a parallel light beam by a condenser lens 15, modulated by a spacial modulator 16 and an image is formed. The image is projected on a screen 2 by a projection lens 17. The light source device 11 for every color, the wavelength of red light, green light and blue light are selected within the ranges from 625 nm to 635 nm, from 525 nm to 535 nm and from 455 nm to 465 nm, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser display device for projecting and displaying a still image or a moving image on a screen using a laser beam.

[0002]

2. Description of the Related Art There is a laser display device capable of displaying a color image by using light of three primary colors of a single wavelength. Conventionally, as a laser display device capable of displaying such a color image, three wavelengths of red, green, and blue are used.
It is known to use a gas laser as a laser that emits laser light of each color light while being used for primary colors.

[0003]

In a laser display device capable of performing color display using a gas laser as described above, it is necessary to employ a gas laser having a sufficient output particularly for red and blue, which have reduced visibility. Conventionally, a krypton ion laser has been used for red, and an argon ion laser has been used for green and blue. In this case, the wavelength of red light is 647 nm (nanometer), the wavelength of green light is 515 nm, and the wavelength of blue light is 488 nm.

However, when the above-mentioned wavelengths are selected as the wavelengths of the red, green, and blue lights, the wavelength of the blue light is too long, and it is difficult to reproduce blue and purple colors.
There is a problem that a sufficiently wide color reproduction range cannot be secured on the XY chromaticity diagram.

Therefore, the wavelength of blue light is defined as argon.
It is conceivable to extend the color reproduction range to cover blue and purple by using another 476 nm wavelength of the blue emission line of the ion laser. In this case, the output of the argon ion laser at a wavelength of 476 nm is considered. However, since the output is relatively lower than that of 488 nm, the efficiency of electric-optical energy conversion is further reduced, and a large-scale power supply is required. is there.

As described above, conventionally, it has been difficult for a laser display device to simultaneously ensure a sufficiently wide color reproduction range and easily obtain a sufficient output.

In the laser display device, since coherent laser light is used, there is a problem that speckle noise appears on a screen due to interference.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a laser display capable of ensuring a sufficiently wide color reproduction range and easily obtaining a sufficient output. It is to provide a device.

[0009] A second object of the present invention is to provide, in addition to the above objects,
An object of the present invention is to provide a laser display device capable of reducing speckle noise on a screen.

[0010]

According to the laser display device of the present invention, the wavelength of the red light generated by the light source device is selected from the range of 625 nm to 635 nm, and the wavelength of the blue light generated by the light source device is selected. The wavelength is selected in the range of 455 nm to 465 nm.

In the laser display device of the present invention, it is sufficient to select the wavelength of red light from 625 nm to 635 nm and the wavelength of blue light from 455 nm to 465 nm. A wide color reproduction range is ensured, and red, green,
It is possible to easily obtain a sufficient output particularly for the red light and the blue light, of which the visibility is reduced, among the light of the three primary colors of blue.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is an explanatory diagram showing a schematic configuration of the laser display device according to one embodiment of the present invention. The laser display device according to the present embodiment enables a color image to be displayed using three primary colors of red, green and blue of a single wavelength.
Image projection unit 1R for projecting a red image to
A green image projecting unit 1G for projecting a green image on the screen 2 and a blue image projecting unit 1B for projecting a blue image on the screen 2. The image projection units 1R, 1G, and 1B are arranged at positions close to each other, and project each color image on the screen 2 on the screen 2 such that corresponding portions of the color images overlap with each other. The screen 2 may be a reflection type or a transmission type.

FIG. 1 shows an image projection unit 1 (1) shown in FIG.
R, 1G, and 1B. It is explanatory drawing which shows the outline structure of (). The image projection unit 1 includes a light source device 11 that generates and emits light of a single wavelength using a laser. This light source device 11 can be regarded as a point light source. The light source device 11 in the red image projection unit 1R generates red light of a single wavelength, and the light source device 11 in the green image projection unit 1G.
Generates green light of a single wavelength, and the light source device 11 in the blue image projection unit 1B generates blue light of a single wavelength.
In the present embodiment, the wavelength of the red light is changed from 625 nm to 63
5 nm, the wavelength of green light is selected from 525 nm to 535 nm, and the wavelength of blue light is 455 nm.
465 nm.

The image projection unit 1 further includes a collimator lens 12 for converting the light emitted from the light source device 11 into a parallel light beam.
And an optical deflector 13 as a deflecting means for deflecting the light from the collimator lens 12 at a predetermined frequency and a predetermined deflection angle.
A fly-eye lens array 14 for equalizing the light deflected by the optical deflector 13, a condenser lens 15 for condensing the light passing through the fly-eye lens array 14, and a light passing through the condenser lens 15. A spatial modulator 16 as a spatial light modulator for spatially modulating light to form an image, and a projection lens 17 for projecting the image formed by the spatial modulator 16 on the screen 2. It has.

As the light deflector 13, for example, a vibrating mirror that deflects light by vibrating a mirror surface that reflects light can be used. As the vibrating mirror, an electromagnetically driven resonance vibrating mirror that vibrates the mirror surface at a mechanical resonance point and electromagnetically drives the mirror surface with a voice coil or the like can be used. In addition, as the vibrating mirror, a mirror that vibrates the mirror surface using a piezo element or the like may be used.

The fly-eye lens array 14 is an array of lenses in which a plurality of small lenses (referred to as elements in the present application) are arranged, and each element forms a secondary light source. In the present embodiment, the fly-eye lens array 14 forms a secondary light source array on the front focal plane of the condenser lens 15, and the condenser lens 15 converts each light from the secondary light source array into a parallel light beam as a spatial light flux. Table 16
To illuminate the spatial modulator 16 uniformly.

The spatial modulator 16 is, for example, 300,000 to 1
It has about one million pixels and spatially modulates the passing light based on a video signal corresponding to the video to be displayed to form an image. The projection lens 17 converts the image formed by the spatial
It is designed to be projected upward.

FIG. 3 is an explanatory diagram showing an example of a detailed configuration of the image projection section 1 shown in FIG. In the image projection unit 1 in the example shown in FIG. 3, a vibrating mirror such as an electromagnetically driven resonance vibrating mirror is used as the optical deflector 13, and a reflective spatial modulator is used as the spatial modulator 16. In addition, the image projection unit 1 in the example shown in FIG. 3 further reflects light from the quarter-wave plate 17 disposed on the front side of the reflection type spatial modulator 16 and the condenser lens 15. Then, the light is made to enter the spatial light modulator 16 substantially perpendicularly through the quarter-wave plate 17, and the light modulated by the spatial light modulator 16 and transmitted through the quarter-wave plate 18 is transmitted. Projection lens 1
And a polarizing beam splitting plate 19 as a polarizing beam splitter for making the light incident on the light source 7.

The reflection type spatial modulator 16 is, for example, a reflection type liquid crystal light valve or a type which modulates light spatially by controlling reflection, transmission, diffraction, etc. of light by mechanical operation. , A digital micromirror device (trade name of Texas Instruments Co., USA), and the like.

Next, the operation of the image projection unit 1 shown in FIG. 3 will be described. The linearly polarized light emitted from the light source device 11 is converted into a parallel light beam by a collimator lens 12, deflected by an optical deflector 13 and applied to a fly-eye lens array 14. Is formed. Each light from the secondary light source array is converted into a parallel light flux by the condenser lens 15, reflected by the polarization beam splitting plate 19, passed through the quarter wavelength plate 18, becomes circularly polarized light, The light enters the modulator 16 almost perpendicularly. The light spatially modulated by the spatial modulator 16 passes through the quarter-wave plate 18 again, becomes linearly polarized light whose polarization direction is orthogonal to the light on the outward path, and enters the polarization beam splitting plate 19. Then, the light passes through the polarizing beam splitting plate 19 and is projected on the screen 2 by the projection lens 17. The screen 2 has a red image projection unit 1
The red, green, and blue images are projected so as to be superimposed by the R, green image projecting unit 1G, and blue image projecting unit 1B. As a result, a color image is displayed on the screen 2.

As shown in FIG. 3, by using a reflection type spatial modulator 16, a quarter wavelength plate 18, and a polarization beam splitting plate 19, the reflection type spatial modulator 16 can be used. It becomes possible to make light incident substantially perpendicularly, and it is possible to use light efficiently.

The laser display device according to the present embodiment uses red, green, and blue lights of a single wavelength, and at least one of the three lights is a solid-state capable of continuous oscillation. It can be continuous and coherent output light of a laser or continuous and coherent light generated based on light generated by wavelength conversion of output light of a solid-state laser.

Here, an example of a method of generating each of red, green, and blue lights will be described with reference to FIGS. FIG.
FIG. 3 is a conceptual diagram illustrating an example of a method for generating red light. In this example, a fundamental wave having a wavelength of 1.064 μm out of the output light of a semiconductor laser-excited neodymium-Yag (Nd: YAG) laser as a solid-state laser has a wavelength of 1.57 μm obtained by parametric oscillation through the nonlinear optical medium 21.
And infrared light having a wavelength of 1.57 μm of the infrared light having a wavelength of 3.3 μm, and a wavelength of 1.064 μm of a neodymium / Yag laser.
With respect to the m fundamental waves, red light having a wavelength of 0.63 μm (630 nm), which is a sum frequency component, is generated through the nonlinear optical medium 22.

FIG. 5 is a conceptual diagram showing an example of a method for generating green light. In this example, the fundamental wave having a wavelength of 1.064 μm of the neodymium-Yag laser is passed through the nonlinear optical medium 23 and the second harmonic having a wavelength of 0.532 μm (532n
m) of green light.

FIG. 6 is a conceptual diagram showing an example of a method for generating blue light. In this example, a fundamental wave having a wavelength of 1.064 μm of the neodymium / Yag laser is converted into a light having a wavelength of 0.532 μm, which is a second harmonic generated through the nonlinear optical medium 24, and a fundamental wave of the wavelength of 1.064 μm of the neodymium / Yag laser. Of the infrared light having a wavelength of 1.57 μm and the infrared light having a wavelength of 3.3 μm obtained by parametric oscillation through the non-linear optical medium 25, the infrared light having a wavelength of 3.3 μm passes through the non-linear optical medium 26 and has a wavelength of 0. 46μ
m (460 nm) blue light is generated.

As the nonlinear optical media 21, 22, 24 to 26, for example, a quasi-phase-matched parametric oscillator obtained by reversing the polarization of lithium niobate and a sum frequency mixing device can be used. For example, lithium triborate (LB
O), β barium borate (β-BBO), or the like can be used.

As described above, by generating the single wavelength red, green, and blue light based on the output light of the solid-state laser or the light generated by wavelength conversion of the output light of the solid-state laser, The device 11 can be miniaturized and light can be generated with high efficiency.

For example, in order to obtain a total luminous flux of about 2000 lumens on the screen 2, at present, a single wavelength red,
Although it is most promising to generate green and blue light by wavelength conversion of the output light of the solid-state laser as described above, the present invention uses a solid-state laser to emit red, green and blue light of a single wavelength. Is not limited to what is generated by other lasers, red, green,
Includes those that produce blue light. For example, even when red, green, and blue light is generated using a visible semiconductor laser, the same effect as when a solid-state laser is used can be obtained.

Next, referring to FIGS. 7 to 12, in the present embodiment, the wavelength of red light is changed from 625 nm to 63.
5 nm, the wavelength of green light is selected from 525 nm to 535 nm, and the wavelength of blue light is 455 nm.
The reason why the wavelength is selected in the range of 465 nm to 465 nm will be described.

First, referring to FIG.
The reason why the wavelength is selected in the range of 25 nm to 635 nm and the wavelength of the blue light is selected in the range of 455 nm to 465 nm will be described. FIG. 7 is an XY chromaticity diagram showing a color reproduction range (color gamut) that is possible using three primary colors in the laser display device according to the present embodiment. In this figure, a is the spectral chromaticity locus, b is the European gamut standardized in Europe, c
Is the color gamut by the laser display device according to the present embodiment, d is the color gamut standardized in the NTSC system, e is the actual color gamut in the three-color phosphor of the color television by the NTSC system, and f is the color. Represents the color gamut of the film. In the drawing, R, G, and B indicate the coordinates of the three primary colors red, green, and blue in the laser display device according to the present embodiment. As can be seen from FIG. 7, the color gamut by the laser display device according to the present embodiment is within the spectral chromaticity locus,
It has the widest color reproduction range. Generally, the color reproduction range of a three-color phosphor of a color television is wide in the green direction,
In short, it is characterized by "bright color reproduction", so in the laser display device according to the present embodiment,
It can be seen that “extremely vivid color reproduction” with higher saturation than color reproduction by three-color phosphors of color television is possible.

In general, by selecting a longer wavelength side as the red wavelength and a shorter wavelength side as the blue wavelength among the three primary colors of red, green, and blue, the color reproduction range can be further improved in FIG. It is possible to make it wider. However, if this is done, the luminosity drops in both red and blue, so that the radiant power of the red light and the blue light required to make the colors (for example, a predetermined white) within the color reproduction range obtained by mixing the three primary colors equal. Increases, making implementation difficult. From the viewpoint of reducing the radiation power of red light and blue light required to make the colors within the color reproduction range equal, select the shorter wavelength side as the red wavelength and select the longer wavelength side as the blue wavelength. Is preferred. Therefore, in the present embodiment, it is necessary to secure a sufficiently wide color gamut and
In order to simultaneously obtain sufficient output for red light and blue light, the wavelength of red light is set to 625 nm to 6 nm.
The wavelength of blue light is selected in the range of 455 nm to 465 nm.

Next, the reason why the wavelength of the green light is selected in the range of 525 nm to 535 nm will be described with reference to FIGS. 8 to 10 show the color matching functions of red, green, and blue when the three primary colors are used in the laser display device according to the present embodiment at a wavelength of 380n.
FIG. 9 is a characteristic diagram showing a result calculated in a range from m to 700 nm. FIG. 8 shows that red light is 630 nm and blue light is 460 n.
m, when green light is a single wavelength of 525 nm,
FIG. 9 shows the case where the red light has a single wavelength of 630 nm, the blue light has a single wavelength of 460 nm, and the green light has a single wavelength of 532 nm.
Indicates the case where the red light has a single wavelength of 630 nm, the blue light has a single wavelength of 460 nm, and the green light has a single wavelength of 535 nm. FIG.
FIG. 1 is a characteristic diagram showing, for comparison, a result of calculating color matching functions of red, green, and blue in a three-color phosphor of a color television according to the NTSC system in a wavelength range of 380 nm to 700 nm. 8 to 11, R represents a red color matching function, G represents a green color matching function, and B represents a blue color matching function.

In general, if there are three primary colors that exist, the color matching functions always include a negative portion that cannot be realized purely optically. The color matching function can be said to be the spectral sensitivity curve of each of the red, green, and blue color sensors assuming color reproduction by the color sensor. Therefore, it is desirable that the negative portion that cannot be optically realized is as small as possible. . In the present embodiment, the wavelength of the green light is changed from 525 nm to 535 n.
The reason for selecting the range of m is to minimize the negative portion of the color matching functions of red, green, and blue. 8 to FIG. 10, FIG. 8 shows that the negative part of the blue color matching function is the largest in FIG. 8 to FIG.
However, the negative part of the red color matching function is the largest in FIGS. However, the color matching functions shown in FIGS. 8 to 10 are all negative compared to the red, green, and blue color matching functions of the three-color phosphor of the NTSC color television shown in FIG. The advantage that the part is much smaller is recognized. On the other hand, the wavelength of green light is 52
Beyond the range of 5 nm to 535 nm, the negative part of the blue or red color matching function becomes more prominent and the superiority is lost. Therefore, in the present embodiment, the wavelength of the green light is selected in a range from 525 nm to 535 nm.

Here, referring to FIG. 12, the wavelength of red light is from 625 nm to 635 nm, and the wavelength of green light is 525 nm.
m to 535 nm, blue light wavelength from 455 nm to 46
In the range of 5 nm, the negative part of the color matching function is sufficiently small. FIG. 12 shows wavelengths 625 to 635 of red light.
The wavelength of blue light is 455-465 nm on the Y axis, the wavelength of green light is a parameter, and the negative of the color matching function of each color of red, green, and blue when the wavelength of green light is 525-535 nm. Take the sum of squares of the area integral of
The average value of them is used as an evaluation function, and the value of the evaluation function is shown by a contour line. In the figure, reference numeral 31 denotes an area where the value of the evaluation function is 1.08 or more and less than 1.095, reference numeral 32 denotes an area where the value of the evaluation function is 1.065 or more and less than 1.08, and reference numeral 33 denotes a value where the value of the evaluation function is 1 Reference numeral 34 denotes an area where the value of the evaluation function is 1.035 or more and less than 1.05.
, A reference numeral 35 represents a region where the value of the evaluation function is 1.02 or more and less than 1.035, and a reference numeral 36 represents a region where the value of the evaluation function is 1..
It represents a region from 005 to less than 1.02.

In FIG. 12, the wavelength of the blue light is 460 nm.
The valley of the value of the evaluation function centering on the line of
It falls while opening to the 35 nm side. However, an excessively long wavelength of red light is disadvantageous in terms of visibility. Therefore, a basin centered on a wavelength of 460 nm for blue light and a wavelength of 630 nm for red light is an optimal region. In addition, within the range shown in FIG.
The values fall within the range of 1.1, and all are usable values. That is, within the range shown in FIG. 12, the negative part of the color matching function is sufficiently small.

By the way, in the conventional laser display device, since coherent laser light is used, there is a problem that speckle noise appears on a screen due to interference. In the laser display device according to the present embodiment, the illumination light to the spatial light modulator 16 is made uniform by using the fly-eye lens array 14, and the frame frequency of the spatial modulator 16 is made higher by using the optical polarizer 13. By deflecting the light at a high frequency, the incident angle of the illumination light with respect to the spatial light modulator 16 is oscillated, so that the speckle noise on the screen 2 is reduced (including the case where it disappears). Hereinafter, the reduction of speckle noise in the present embodiment will be described in detail.

First, the relationship between the frequency of light deflection by the optical deflector 13 and the effect of reducing speckle noise will be described. When the light is deflected at a frequency higher than the frame frequency (for example, 30 Hz) in the spatial modulator 16, a plurality of speckle random patterns that change with the deflection are generated within the frame period. , A plurality of random patterns are temporally averaged, and speckle noise is reduced. Here, the larger the number of random patterns in the frame period,
The effect of temporal averaging of the random pattern becomes significant.
Reference "JW Goodman, J. Opt. Soc.
Am. 66 volumes. "Page 1145 (1976)" describes the relationship between the number of random patterns and the effect of reducing speckle noise on human eyes. According to this document, the contrast C of the speckle pattern
Is expressed as follows using the number M of random patterns.

C = 1 / M ^1/2

FIG. 13 shows the relationship of the above equation. Note that the horizontal axis in FIG. 13 is log (M). From the above formula and FIG. 13, for example, when M = 100, the contrast of the speckle pattern decreases from 100% in the case of M = 1 to 10% from log (M) = 2. Therefore, ideally, the frame period or the time during which the human eye is stationary at a certain position (Persistent)
1 which is an approximate value of the time of
If there are 100 or more random patterns in / 20 seconds, the effect of reducing speckle noise becomes significant.

Next, with reference to FIG. 14, the relationship between the light deflection angle by the optical polarizer 13 and the effect of reducing speckle noise will be described. FIG. 14 shows the relative value Rm of the angular amplitude (deflection angle) when the angle of the light beam incident on the fly-eye lens array 14 is vibrated at a frequency higher than the frame frequency of the spatial modulator 16 using the optical polarizer 13. And a power spectrum density function (power spectrum density function). Here, when the wavelength of the output light of the light source device 11 is λ and the aperture of the element of the fly-eye lens array 14 is d, the unit of the relative value Rm of the angular amplitude is λ / d. In FIG. 14, the horizontal axis is the spatial frequency, and the unit is d / (λf)
(Where f is the focal length of the condenser lens 15). Therefore, it can be said that FIG. 14 shows speckle contrast at various spatial frequencies.
As shown in FIG. 14, as the relative value Rm of the angular amplitude increases, the power spectrum density of speckle decreases. Since the unit of the relative value Rm of the angular amplitude is λ / d, as shown in FIG. 14, as the angle amplitude (deflection angle) is larger than λ / d, the power spectrum density of the speckle becomes smaller and the speckle noise is reduced. It can be said that the effect of reduction is remarkable. Therefore, the angle amplitude (deflection angle) is preferably larger than λ / d (radian), and particularly, 5
More than twice is preferred.

By the way, in the configuration shown in FIG. 1, a projection exposure apparatus in which the light source device 11 is replaced by an ultraviolet pulse laser, the spatial modulator 16 is replaced by an IC exposure mask, and the screen 2 is replaced by a photoresistor is known. .
According to the paper "Ichihara et al., SPIE Proceedings, Vol. 1138, pp. 137-143 (1989)" which experimentally analyzed this, λ / d was used as the angular amplitude.
Is described as optimal for the purpose of erasing speckles on the photoresist, which is clearly different from the result shown in FIG. 14 in the present embodiment.

The reason is unknown because the calculation of the power density function of speckle is not shown in the above-mentioned paper, but when a pulse laser is used as in a projection exposure apparatus, the angular amplitude Is not allowed to take only a discrete value, but it is considered that when a continuous wave laser is used as in the present embodiment, the angle amplitude is allowed to take a continuous value.

As described above, regarding the reduction of speckle noise, the frame period or the time during which the human eye is stationary at a certain position (Persistence of vi)
It is preferable that there are 100 or more random patterns of the speckle pattern in 1/20 second, which is the approximate value of the (sion time). Here, considering that a random pattern of 100 speckle patterns is generated in 1/20 second, the deflection frequency of the optical deflector 13 required for that purpose is 2 kHz. On the other hand, the angle amplitude is d = 4 mm,
When λ = 532 nm and Rm = 10, the value is about 1 milliradian. The optical deflector 13 that can deflect such a frequency and an angular amplitude can be sufficiently realized by using a resonance type vibrating mirror.

In the structure shown in FIG. 1, the interval between the secondary light sources formed by the fly-eye lens array 14 is equal to the aperture (period) d of the element of the fly-eye lens array 14. Using such a secondary light source and a condenser lens 15 having a focal length f, a spatial modulator 16
Are illuminated, the parallel light fluxes corresponding to the respective secondary light sources make an angle of d / f with each other.
Interference fringe of the main period p ₁ which is represented by the following formula (1) is formed.

P ₁ = λf / d (1)

When the number of elements of the fly-eye lens array 14 is N, an interference fringe having a sub-period p ₂ expressed by the following equation (2) is formed.

P ₂ = λf / (Nd) (2)

It is not preferable that the above-described interference fringes affect the image on the screen 2. Therefore, assuming that the pixel cycle of the spatial modulator 16 is p, the pixel cycle p is
If the main period of the interference fringes on the spatial modulator 16 is made equal to p ₁ = λf / d, the luminous flux illuminating each pixel of the spatial modulator 16 becomes uniform, and the interference fringes of the main period become the screen 2. It is possible to prevent the above image from being affected.
In this case, since the interference fringes of the sub-period are integrated in each pixel, they do not affect the image on the screen 2.

As described above, the pixel period p of the spatial modulator 16 is changed to the main period p ₁ = λf of the interference fringe on the spatial modulator 16.
/ D, the focal length f of the condenser lens 15 is set to p · d /
may be set to λ.

Further, when the optical deflector 13 is driven under this condition, the power spectrum density function of the speckle on the spatial modulator 16 is as shown in FIG. The component is 1 / p (= d /
(Λf)) shows a maximum value for each.

Here, the pixel size of the spatial modulator 16 is
Naturally, since the pixel cycle is equal to or less than the pixel period p, the speckle pattern having a size exceeding the pixel size is divided into the pixel size or less when the spatial modulator 16 is driven by the video signal, and is formed on the surface of the spatial modulator 16. not exist. Therefore, a speckle pattern larger than the pixel size cannot pass through the surface of the spatial modulator 16.

On the other hand, a speckle pattern smaller than the pixel size reaches the surface of the screen 2 via the projection lens 17 and finally reaches the viewer's pupil. , Since it is selected to be lower than the viewer's eye resolution, speckle patterns smaller than the pixel size cannot be resolved on the retina of the viewer's eye, and are averaged by being integrated on the retina.

In summary, regarding the reduction of speckle noise in the laser display device according to the present embodiment, both the use of the spatial modulator 16 and the vibration of illumination light to the spatial modulator 16 by the optical deflector 13 are required. is important. Only by the vibration of the illumination light by the light deflector 13, as described in the paper analyzing the projection exposure apparatus described above,
The speckle pattern recorded on the photoresist cannot be completely eliminated. This is because the resolution of the photoresist is much higher than the resolution of the eyes. In the laser display device according to the present embodiment, the spatial modulator 16 shares the function of subdividing the speckle pattern to the eye resolution or less.

On the other hand, the use of the spatial modulator 16 alone cannot sufficiently suppress the energy of speckles smaller than the pixel size, so that even if the speckle cannot be resolved on the retina, the flicker due to interference remains as a perception. Therefore, in the laser display device according to the present embodiment, the light deflector 1
The vibration of the illumination light by 3 plays a role of sufficiently suppressing the energy of speckles smaller than the pixel size.

The period (main period) of the interference fringes on the spatial modulator 16 is given by the equation (1). More precisely, the following equation (3) holds. p ₁ sin θ = λ (3) where θ is given by the following equation (4). tan θ = f / d (4)

Therefore, when the image height is y and y 'and the angle of view is θ, it is desirable that the condenser lens 15 has the characteristic of y' = f sin θ, rather than the characteristic of y = ftan θ. . Here, y'-y is called distortion, and for example, if the condenser lens 15 has a doublet configuration composed of a compound lens of a concave lens and a convex lens, -1
% Of negative distortion is preferable. here,
Assuming that Δy = (y′−y) / y is called% distortion, FIG. 15 shows the relationship between the incident angle θ and the% distortion.
In the figure, reference numeral 41 denotes a calculated value Δy = (sin θ) of the% distortion in the case of a lens having the characteristic of y ′ = fsin θ.
−tan θ) / tan θ, and reference numeral 42 represents% distortion based on the design value of the lens having the doublet configuration. As shown in this figure, when the condenser lens 15 has a doublet configuration, a distortion of about -1% occurs. This is set to θ = 10 ° in a lens having the characteristic of y ′ = fsin θ. % Distortion at time -1.5
%.

The reason why the condenser lens 15 preferably has a negative distortion will be described below. In the illumination optical system, when the focal length is f, the relationship between the image height y and the incident angle θ is represented by the following expression (5) (this is referred to as a sine condition). y = fsinθ (5)

Then, the following equation (6) is established. dy = fcosθdθ (6)

On the other hand, the relationship between the irradiance E and the radiance I is expressed by the following equation (7). E2πydy = I (θ) 2πsin θdθ (7) Accordingly, the following equation (8) is established. I (θ) = Efdy / dθ (8)

When the limit operation is performed by substituting equation (6) into equation (8), the following equation (9) is obtained. I (0) = Ef ² (9)

From equations (8) and (9), the following equation (10) is obtained.
Is obtained. I (θ) = I (0) cos θ (10)

Therefore, an object illuminated by the illumination optical system satisfying the expression (5) can be regarded as a surface light source having a constant radiance, which is preferable as the illumination optical system. Since the condenser lens 15 forms an illumination optical system for illuminating the spatial modulator 16, the one having the characteristic of Expression (5) is
Is preferable because it can be uniformly illuminated. Therefore,
For example, the condenser lens 15 has a doublet configuration,
It is preferable to provide a negative distortion because the characteristic has a characteristic close to the equation (6).

As described above, according to the laser display device of this embodiment, the wavelength of the red light is
5 to 635 nm, and the wavelength of blue light is 455
４６465 nm, so that the color reproduction range can be sufficiently wide compared to the case where a laser display device is realized using a gas laser as in the past, and the visibility of red light and blue light is also high. Since it is high, it is possible to achieve both securing a sufficiently wide color reproduction range and easily obtaining a sufficient output for red light and blue light. According to the laser display device according to the present embodiment, further,
Since the wavelength of the green light is selected in the range of 525 to 535 nm, it is possible to minimize the negative portion of the color matching function of each of red, green, and blue as much as possible, which facilitates realization. As a result, the conventional NTSC color television 3
It is possible to realize a display device having high saturation even in comparison with color reproduction by color phosphors, in other words, characterized by “extremely vivid color reproduction”.

Further, according to the laser display device of the present embodiment, the use of the spatial modulator 16 and the light deflector 1
The speckle noise that reaches the eyes of the viewer can be effectively reduced by combining the vibration of the illumination light with respect to the spatial modulator 16 by 3. As a result, as compared with a display using a conventional incoherent light source, a highly efficient optical path design utilizing the characteristics of a coherent light source despite no speckle noise (for example, as shown in FIG. 3). Reflection type spatial modulator 1
6 and a quarter-wave plate 18 and a polarization beam splitting plate 19), and an optical path design utilizing a point light source as compared with a light emitting diode or the like can be realized, and a display with high efficiency can be realized. The device can be realized.

The present invention is not limited to the above embodiments. For example, in the embodiments, the image projection unit 1 for each color is used.
Although an example of a laser display device in which R, 1G, and 1B are independent has been described, the present invention, for example, sequentially irradiates each color light to one spatial modulator and converts the spatial modulator to each color image. The present invention can also be applied to a surface-sequential type laser display device that is sequentially driven according to the conditions. As described above, when the optical system is commonly used for each color light, among the various preferable conditions described in the embodiment, the one including the wavelength λ is most regarded as the wavelength λ and has the highest visibility and the human eye. May be satisfied with respect to the wavelength of green light having a high resolution.

The present invention is not limited to a laser display device that forms an image by spatially modulating light using a spatial modulator, but also modulates the intensity of light temporally and scans light to form an image. And a laser display device that modulates the intensity of light temporally and spatially to form an image. When the light intensity is modulated over time,
The drive of the laser may be controlled to modulate the output light of the laser itself, or the light emitted from the laser may be modulated by a modulator.

[0067]

As described above, claims 1 to 10
According to the laser display device according to any one of
The wavelength of red light was selected in the range of 625 nm to 635 nm, and the wavelength of blue light was selected in the range of 455 nm to 465 nm. This has the effect of being compatible with easy acquisition.

According to the laser display device of the second aspect, the wavelength of the green light is selected from the range of 525 nm to 535 nm.
The negative portion of the color matching functions of green and blue can be reduced as much as possible, and this has the effect of facilitating realization.

According to a fifth aspect of the present invention, there is provided the laser display device, further comprising a spatial light modulating means, wherein the light deflecting means deflects the light at a frequency higher than the frame frequency of the spatial light modulating means. Since the light is applied to the spatial light modulating means, it is possible to further reduce the speckle noise on the screen.

According to the laser display device of the eighth aspect, the wavelength of the light from the light source device is λ, the size of the aperture of each element of the fly-eye lens array is d, and the pixel period of the spatial light modulator is Where p is p, the focal length of the condenser lens is p · d / λ, so that interference fringes generated by the fly-eye lens array can be further prevented from affecting the image on the screen. To play.

According to the laser display device of the ninth aspect, a reflective spatial light modulator is used as the spatial light modulator, and the quarter-wavelength light modulator disposed on the front side of the spatial light modulator. The light from the one-wavelength plate and the condenser lens is reflected and made incident on the spatial light modulating means substantially perpendicularly through the quarter-wavelength plate, and modulated by the spatial light modulating means. Since a polarizing beam splitter for transmitting the light passing through the wavelength plate and making the light enter the projection lens is provided, an effect of further improving the light use efficiency can be obtained.

Further, according to the laser display device of the tenth aspect, since the condenser lens has a negative distortion, it is possible to further illuminate the spatial light modulator more uniformly. Play.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a schematic configuration of an image projection unit in a laser display device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic configuration of a laser display device according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a detailed configuration of an image projection unit illustrated in FIG. 1;

FIG. 4 is a conceptual diagram showing an example of a method for generating red light in the laser display device according to one embodiment of the present invention.

FIG. 5 is a conceptual diagram showing an example of a method for generating green light in the laser display device according to one embodiment of the present invention.

FIG. 6 is a conceptual diagram showing an example of a method of generating blue light in the laser display device according to one embodiment of the present invention.

FIG. 7 is an XY chromaticity diagram showing a possible color reproduction range using three primary colors in the laser display device according to one embodiment of the present invention.

FIG. 8 is a characteristic diagram showing a color matching function when three primary colors are used in the laser display device according to one embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a color matching function when three primary colors are used in the laser display device according to one embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a color matching function when three primary colors are used in the laser display device according to one embodiment of the present invention.

FIG. 11 shows color television 3 according to the NTSC system.
FIG. 4 is a characteristic diagram showing a color matching function in a color phosphor.

FIG. 12 is an explanatory diagram showing that the negative portion of the color matching function becomes sufficiently small when three primary colors are used in the laser display device according to one embodiment of the present invention.

FIG. 13 is a characteristic diagram showing a relationship between the number of random patterns of the speckle pattern and the contrast of the speckle pattern.

FIG. 14 is a characteristic diagram showing a relationship between a deflection angle and a power spectrum density of speckle when light is deflected by an optical deflector in the laser display device according to one embodiment of the present invention.

FIG. 15 is a characteristic diagram showing a relationship between an incident angle of a lens and distortion.

[Explanation of symbols]

1R: red image projection unit, 1G: green image projection unit, 1B ...
Blue image projection unit, 2 ... Screen, 11 ... Light source device, 1
2 Collimator lens, 13 Optical deflector, 14 Fly-eye lens, 15 Condenser lens, 16 Spatial modulator, 17 Projection lens

Claims (10)

[Claims] 1. A light source device for generating light of three primary colors of red, green, and blue of a single wavelength using a laser, and displaying a color image using light of the three primary colors generated by the light source device. In the laser display device, the wavelength of the red light generated by the light source device is 625.
The wavelength of the blue light generated by the light source device is selected from the range of nanometers to 635 nanometers.
A laser display device characterized by being selected in the range of 55 nanometers to 465 nanometers. 2. The laser display device according to claim 1, wherein a wavelength of the green light generated by the light source device is selected in a range from 525 nanometers to 535 nanometers. 3. The light source device generates at least one of the three primary colors of red, green and blue by continuous and coherent output light of a solid-state laser or wavelength conversion of output light of a solid-state laser. 2. The laser display device according to claim 1, wherein the light is continuous and coherent light generated based on the light to be emitted. 4. A spatial light modulator for spatially modulating light to form an image, and a condenser lens for condensing light from the light source device and irradiating the light to the spatial light modulator. The laser display device according to claim 1, further comprising: a projection lens configured to project an image formed by the spatial light modulator on a screen. 5. A light deflecting means provided between the light source device and the condenser lens, for deflecting light from the light source device, provided between the light deflecting means and the condenser lens, A fly-eye lens array for making the light deflected by the light deflecting means uniform and entering the condenser lens, wherein the light deflecting means deflects the light at a frequency higher than a frame frequency in the spatial light modulating means. The laser display device according to claim 4, wherein 6. The light deflecting means has a deflection angle larger than λ / d, where λ is the wavelength of light from the light source device and d is the size of the opening of each element of the fly-eye lens array. The laser display device according to claim 5, wherein light is deflected. 7. The laser display device according to claim 5, wherein said light deflecting means has an electromagnetically driven resonance vibration mirror. 8. The condenser lens, wherein λ is the wavelength of light from the light source device, d is the size of the aperture of each element of the fly-eye lens array, and p is the pixel period of the spatial light modulator. 6. The laser display device according to claim 5, wherein the focal length of the laser display is p · d / λ. 9. A reflection type spatial light modulator is used as said spatial light modulator, and a quarter-wave plate provided on the front side of said spatial light modulator, and a light reflected from said condenser lens. The reflected light is made to enter the spatial light modulating means substantially perpendicularly through the quarter-wave plate, and is modulated by the spatial light modulating means and passes through the quarter-wave plate. The laser display device according to claim 4, further comprising a polarizing beam splitter that transmits light and makes the light enter the projection lens. 10. The laser display device according to claim 4, wherein the condenser lens has a negative distortion.