JP2001281599A - Projection display device - Google Patents

Abstract

(57) [Problem] To provide a projection type display device that uses a plurality of laser light sources as an illumination light source and has high light use efficiency and can obtain a bright and high-quality projected image. SOLUTION: It is composed of a plurality of laser light sources 201 arranged in a matrix, a coupling optical system 209 corresponding to a light emitting point of the laser light source, an optical fiber array 210, a condensing optical system 202, and a polarization conversion optical system 203. RG
If an illumination system that generates B light is used, the light utilization efficiency of the illumination system can be improved, the size of the projection display device can be reduced, and the color reproduction range of the projected image can be widened.

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 for projecting and displaying an image displayed on a two-dimensional light modulator, and more particularly to a projection type display device using a liquid crystal light valve.

[0002]

2. Description of the Related Art A light valve type liquid crystal projector using a liquid crystal display element is widely used. This liquid crystal projector uses a so-called TN (Twisted Nematic) liquid crystal mode or an ECB (Electrically Controlled Birefringence) mode to polarize light. An image is formed by controlling the state. Using a thin film transistor or a transistor on a Si semiconductor substrate as a driving element, a fine image is formed as a transmission type or reflection type liquid crystal light valve.

[0003] By the way, such a light-bulb type projection display device requires a projection light source. In the prior art, a high-intensity discharge lamp such as a high-pressure mercury lamp or a metal halide lamp is generally used as the light source. Have been.

Further, a projection type display device using a solid light source such as a laser diode as a projection light source as disclosed in Japanese Patent Application Laid-Open Nos. 10-293545 and 11-65477 has been devised. However, those devices make the light source light incident on the light valve as it is.

[0005]

However, when a high-intensity discharge lamp such as a metal halide lamp or a xenon lamp is used as a light source as in the prior art, the light-collecting efficiency of the light source is poor. On the other hand, when a solid-state light source is used, There is a problem in that energy cannot be used because the polarized light cannot be used effectively.

In general, such a display device requires a light source of three primary colors for color display. However, since a high-intensity discharge lamp is a white light source, a color separation illumination optical system for separating light into three primary colors by a dichroic mirror or the like. This requires a system, and further requires an air cooling device for heat dissipation, which has been a bottleneck in miniaturization of the device.

On the other hand, solid-state light sources such as semiconductor lasers and light-emitting diodes have lower outputs than high-intensity discharge lamps, and cannot be said to be sufficient for use as a single light source. Furthermore, since the light source has a high spatial coherency, the use of the light source simply causes a problem of generation of speckle.

SUMMARY OF THE INVENTION An object of the present invention is to provide a small-sized projection display device which is bright by controlling the plurality of laser light sources and the polarization of the light from the light sources, has no unevenness in the light amount, and has a small size.

[0009]

According to the first aspect of the present invention, there is provided an illumination system for generating red light, green light, and blue light, and a light output from the illumination system. A two-dimensional light modulator that forms an optical image according to image information, a red light, a green light, a dichroic prism that synthesizes an image corresponding to blue light, and a projection lens that projects the image. In the projection display device provided, the illumination system includes a plurality of laser light sources arranged in a matrix, a coupling optical system corresponding to a light emitting point of the laser light source, an optical fiber array, and light from the optical fiber array. It is characterized by comprising a condensing optical system for condensing light, and a polarization conversion optical system for separating light from the condensing optical system into respective polarization directions.

According to this, speckle which causes flicker can be suppressed, and since the light emitting point of the light source is small, ideal light control can be performed, and loss of light amount can be suppressed to a small value.

Further, according to a second aspect of the present invention, the polarization conversion optical system includes a polarization beam splitter for separating incident light into P-polarized light and S-polarized light, and a half-wavelength for rotating one polarized light component by 90 degrees. It is characterized by comprising a plate and a reflecting mirror prism that bends the traveling direction of the reflected light.
According to this, polarized light can be effectively used for projection without waste.

According to a third aspect of the present invention, the condensing optical system comprises a converging lens array having a positive power, and a focal length of the converging optical system is determined by a position of a polarization beam splitter of the polarization conversion optical system and the optical fiber array. Are set so that the position of the emission end is substantially conjugate. According to this, the light from the light source can be effectively introduced into the polarization conversion system.

Further, the invention according to claim 4 is that the entire size of the emission end of the optical fiber array constituting the illumination system including the plurality of laser light sources is larger than the light receiving area of the two-dimensional spatial light modulator. Features. According to this, it is possible to reduce a component deviating from the entrance pupil of the projection lens.

Further, the invention according to claim 5 is characterized in that the light source array comprising the plurality of laser light sources has different numbers of light sources corresponding to red light, green light and blue light, respectively. According to this, a projection image with good color balance is selected.

Further, the invention according to claim 6 is characterized in that an illumination lens for multiplexing an image near the condensing optical system on the two-dimensional spatial light modulator is provided.
According to this, it is possible to provide uniform illumination to the two-dimensional spatial light modulator.

According to a seventh aspect of the present invention, an illumination system for generating red light, green light, and blue light, and light output from the illumination system is modulated according to image information to form an optical image. In a projection display device including a two-dimensional light modulator, a dichroic prism that synthesizes an image corresponding to the red light, the green light, and the blue light, and a projection lens that projects the image, the illumination system includes a matrix. A plurality of laser light sources, a coupling optical system in which a plurality of light emitting points of the laser light source correspond to one lens, an optical fiber array corresponding to one optical fiber, and a collection corresponding to one lens. It is characterized by comprising an optical optical system and a polarization conversion optical system for separating the light from the light collecting optical system into respective polarization directions. According to this, it is possible to project a larger amount of light.

Further, the invention according to claim 8 is characterized in that a red light,
An illumination system that generates green light and blue light; a two-dimensional light modulator that modulates light output from the illumination system according to image information to form an optical image; and the red light, green light, and blue light A dichroic prism for synthesizing an image corresponding to the image, and a projection display device including a projection lens for projecting the image, wherein the illumination system has a plurality of laser light sources arranged in a line, and a line-shaped solid light source. A coupling optical system with a light emitting point corresponding to one lens, an optical fiber array with one optical fiber, a condensing optical system with one lens corresponding to multiple optical fibers, and a condensing optical system Is characterized by comprising a polarization conversion optical system that separates the light in each polarization direction. According to this, a simple condenser lens system can be configured.

[0018]

(Embodiment 1) Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a basic configuration diagram of an optical system of a projection display according to an embodiment of the present invention. Red light (R light), green light (G light), blue light (B light)
Around the dichroic prism 101 that synthesizes
On the three surfaces, three transmission type two-dimensional spatial light modulators 102, 103, and 104 for red (R), green (G), and blue (B) are arranged. The projection lens 105 is arranged on the remaining surface. These transmission type two-dimensional spatial light modulators 102,
Illumination systems 106, 107, and 108 each including a laser light source of a corresponding color are provided for 103 and 104, respectively.

The two-dimensional spatial light modulator 102 used here,
Reference numerals 103 and 104 denote devices for modulating the transmittance of incident light according to image information of each color. For example, a transmission type liquid crystal display element is typical, and specifically, a liquid crystal display element provided with a thin film transistor (TFT) for each pixel, a so-called active matrix type TN (Twisted Nematic) liquid crystal display element is generally used. It is. The two-dimensional spatial light modulators 102, 103, and 104 used in this embodiment are polysilicon TFT-LCDs. The principle of operation is to control the light transmittance by controlling the electro-optic effect of the liquid crystal, in particular, the polarization state by the electric field.

Next, when images corresponding to RGB are formed on the two-dimensional spatial light modulators 102, 103, and 104, these are synthesized by the dichroic prism 101 and image-formed and projected on the screen by the projection lens. Thus, a color image is reproduced.

FIG. 2 is a diagram showing an outline of an illumination system of the projection type display device of the present invention. Only one color is taken out for simplicity. Light from the laser light source is condensed on the incident side end face of the optical fiber array 210 by the coupling optical system 209 provided corresponding to the light emitting points 201 of the 4 × 4 light sources. A condensing optical system 202 is provided on the exit side end face, and the condensed light enters a polarization conversion optical system 203.

The polarization conversion optical system 203 comprises a polarization beam splitter 204 and a half-wave plate 205,
After separation into a polarized light component and an S-polarized light component, one of the polarized light components is rotated by 90 degrees by the half-wave plate 205.
When either of the separated lights is reflected by the reflecting mirror prism 206 in the same direction as the traveling direction of the light, light with uniform polarization can be generated effectively. In this case, since the polarization splitting film of the polarization beam splitter 204 only needs to have polarization selectivity in the emission spectrum region of the laser light source, a narrow band design is sufficient.

Further, in the present embodiment, the polarizing beam splitter 204, the reflecting mirror prism 206, and the half-wave plate 2
05 corresponds to the light emitting point 201 in a one-to-one correspondence and is arrayed. More specifically, the condenser optical system 202 and the coupling optical system 209 used a lens array composed of a convex lens having a positive power, and the laser light source used was an array of semiconductor lasers. Each lens of the coupling lens array 209 corresponds to the light emitting point 201 of the semiconductor laser.

When a laser is used as a light source, the light source emits light with high polarization and very high spatial coherency. Therefore, when used simply as a light source, the projected image has many speckles and is visually recognized as flicker.

In this embodiment, the light emitted from the semiconductor laser is coupled to the coupling lens array 209 as shown in FIG.
And is introduced into the optical fiber array 210. Polarization and phase are complicatedly disturbed while being reflected and propagated in the optical fiber array 210, and as a result, spatial coherency causing speckle can be reduced. Next, light generated from the output end of the optical fiber array 210 is
The light is condensed again by the converging array lens 202 and enters the polarization conversion optical system 203.

The focal length of the condenser lens array 202 is set so that the position of the polarization beam splitter 204 of the polarization conversion optical system 203 and the position of the exit end of the optical fiber array 210 are substantially conjugate. By doing so, almost all of the light from the light source can be made incident on the polarizing beam splitter 204. In the case of FIG. 2, the polarizing beam splitter 204, the reflecting mirror prism 206, the half-wave plate 20
5 are linearly accumulated in a direction perpendicular to the paper surface of FIG. This is because simpler manufacturing is possible than an individual array.

Further, in the entire illumination system including the condenser lens array 202, two images near the condenser lens array 202
The illumination lens array 211 and the illumination lens 207 are designed to form multiple images on the three-dimensional spatial light modulator 208. The condenser lens array 202 has a configuration in which a plurality of rectangular single lenses similar to the display unit of the two-dimensional light modulator 208 are arranged in a matrix. In this way, uniform illumination can be provided. In FIG. 2, light rays are drawn with respect to one central condensing lens array, but light passing through the converging lens array 202 on the end side is similarly condensed on the display unit of the two-dimensional light modulator 208. ing.

Next, the laser light sources used in this embodiment are shown in Table 1.
Shown in Table 1 R AlGaInP based semiconductor laser RLD GLD Pumped Nd: YAG SHG B GaN based semiconductor laser Nichia Corporation

For the green light of the laser light source, a solid-state laser excited by a semiconductor laser was used in consideration of luminous efficiency. The red and blue semiconductor lasers were mounted in a matrix on an alumina ceramic substrate 209 having good thermal conductivity.

The overall size of the emission end of the optical fiber array 210 is larger than that of the two-dimensional spatial light modulator 208. This is to reduce a component that deviates from the entrance pupil of the projection lens due to the shift of the optical axis between the transmitted polarized light by the polarization conversion optical system 203 and the polarized light whose polarization plane is rotated. By doing so, a bright projected image was obtained without using a large-diameter projection lens.

For the sake of color balance, the number of semiconductor lasers mounted on the solid-state laser array is 2 × 2 for R and 3 × 3 for B.
It can also be adjusted as follows.

As described above, since the spectrum width of each of the RGB colors of the solid-state light source is narrower than that of the illumination light which has been color-separated by the conventional dichroic mirror or the like, the wavelength selection characteristic of the coating of the dichroic prism 101 for synthesis is reduced. Even if not steep, sufficient three primary colors can be synthesized.

When a larger amount of light is required, it is necessary to integrate many laser light sources as shown in FIG. As a result, the light emitting points approach. In this case, as shown in FIG. 3, a plurality of light emitting points 301 are associated with one lens of the coupling lens array 309, one fiber of the optical fiber array 310, and one lens of the condenser lens array 302, and are located at one polarization beam splitter position. Can be irradiated.
303 is a polarization conversion system, 311 is an illumination lens array, 30
Reference numeral 7 denotes an illumination lens.

As shown in FIG. 4, light emitting points 401 of the laser array are formed in a line shape, and light from each light emitting point is condensed by one lens of the coupling lens array 409, and one fiber of the optical fiber array 410 is formed. And the exit ends of the plurality of optical fibers are condensed into a condenser lens array 4.
02 corresponding to one lens. The light condensed by the condenser lens 402 enters the polarization conversion optical system 403. 411 is an illumination lens array, and 407 is an illumination lens.

Next, an RGB color image formed on a two-dimensional spatial light modulator (not shown) illuminated with RGB light is synthesized by a dichroic prism (not shown). Since the spectral width of each of the R, G, and B colors of the laser is narrower than that of illumination light that has been color-separated by a conventional dichroic mirror or the like, it is sufficient even if the wavelength selection characteristics of the coating of the dichroic prism for synthesis are not sharp. There is an advantage that three primary colors can be combined.

The semiconductor laser used here does not require a very controlled wavelength or far-field pattern as used in optical communication and memory devices, so that the DFB mirror structure at the laser end can be simplified.

The above description has focused on the example of a semiconductor laser, but a solid state light source such as a semiconductor laser pumped solid laser can similarly constitute a projection display.

[0038]

As described above, the projection type display apparatus of the present invention does not need to separate the light source light into RGB as in the conventional liquid crystal projection type projector, and can reduce the size of the illumination optical system. Since the light emitting point of the light source is small, ideal light control is possible, and the loss of light quantity can be suppressed to a small value. Further, the spatial coherence unique to the laser can be reduced, and the occurrence of speckle can be reduced. Further, since the polarization of the laser light once broken can be used effectively, the loss of the light amount can be suppressed. As described above, it is possible to obtain a bright projected image with high light use efficiency. Also,
In order to increase the light output of the projected image, when multiple light sources are arrayed as in the present application, the load per element is reduced,
Further, heat generation can be dispersed, which has the effect of improving the reliability of the light source. Furthermore, even if the light source varies or even one of the light sources fails, the function as the projection display device is not lost. Further, the cooling system, which was indispensable for the light source, can be simplified. Since light from a plurality of solid-state light sources can be combined and used, a projection image with sufficient brightness can be easily obtained. Further, according to the present invention, illumination of uniform illuminance can be given to the two-dimensional spatial light modulator, so that a high-definition projected image without uneven brightness can be obtained. In addition, since the solid-state light source can obtain light with high color purity in a narrow wavelength band, according to the present invention, the color reproduction range is wider than when a white light source according to the related art is used, and as a result, a sufficiently high color reproduction range is obtained. A high quality projected image can be obtained.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an optical system of a projection display according to an embodiment of the present invention.

FIG. 2 is a sectional view of an illumination system of the projection display device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of an illumination system including a plurality of light emitting points according to the embodiment of the present invention.

FIG. 4 is a sectional view of an illumination system of the linear light source array according to the embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 101 dichroic prism 102, 103, 104 two-dimensional spatial light modulator 105 projection lens 106, 107, 108 illumination system composed of laser light sources of R, G, B colors 201 emission point of laser light source 202 light-collecting optical system 203 polarization conversion Optical system 204 Polarizing beam splitter 205 1/2 wavelength plate 206 Reflecting mirror prism 207 Illuminating lens 208 Two-dimensional spatial light modulator 209 Coupling optical system 210 Optical fiber array 301 Plural light emitting points 302, 402 Condensing lens array 303, 403 Polarization Conversion optical system 309, 409 Coupling lens array 310, 410 Optical fiber array 401 Linear laser light source array

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 21/14 G03B 33/12 33/12 G09F 9/00 337Z G09F 9/00 337 360D 360 H04N 9/31 C H04N 9/31 G02F 1/1335 530 F-term (reference) 2H088 EA13 EA15 EA18 HA08 HA15 HA20 HA23 HA24 HA25 HA28 HA30 JA05 2H091 FA10Z FA11Z FA21Z FA24Z FA26Z FA29Z FA46Z GA13 HA07 LA09 LA16 MA07 2H009 AA09 BA0908 DA05 DA09 GB01 GB05 HC00 HC01 HC22 HD00 JA00 JA19 JB06 5G435 AA03 AA04 BB01 BB12 DD04 DD06 DD09 DD13 FF05 FF11 GG02 GG03 GG18 GG23 GG26

Claims (8)

[Claims] An illumination system that generates red light, green light, and blue light; a two-dimensional light modulator that modulates light output from the illumination system according to image information to form an optical image; In a projection display device including a dichroic prism that synthesizes an image corresponding to red light, green light, and blue light, and a projection lens that projects the image, a plurality of laser light sources in which the illumination system is arranged in a matrix A coupling optical system corresponding to a light emitting point of the laser light source, an optical fiber array, a condensing optical system for condensing light from the optical fiber array, and a light beam from the condensing optical system in each polarization direction. And a polarization conversion optical system for separating the light into a plurality of light beams. 2. The polarization conversion optical system converts incident light into P-polarized light,
A polarization beam splitter for splitting the polarized light into S-polarized light, a half-wave plate for rotating one polarized light component by 90 degrees, and a reflecting mirror prism for bending the traveling direction of the reflected light. Item 2. The projection display device according to Item 1. 3. The condensing optical system comprises a condensing lens array having a positive power. The focal length of the condensing optical system is substantially conjugate between the position of the polarization beam splitter of the polarization conversion optical system and the position of the exit end of the optical fiber array. The projection type display device according to claim 1, wherein the projection type display device is set to be: 4. The two-dimensional spatial light modulator according to claim 1, wherein the entire size of the emission end of the optical fiber array constituting the illumination system including the plurality of laser light sources is larger than the light receiving area of the two-dimensional spatial light modulator. Projection display device. 5. The projection display device according to claim 1, wherein the light source array including the plurality of laser light sources has different numbers of light sources corresponding to red light, green light, and blue light, respectively. 6. The projection display device according to claim 1, further comprising an illumination lens for multiplexing an image in the vicinity of the condensing optical system onto the two-dimensional spatial light modulator. 7. An illumination system that generates red light, green light, and blue light, a two-dimensional light modulator that modulates light output from the illumination system according to image information, and forms an optical image, Red light, green light, a dichroic prism that synthesizes an image corresponding to blue light, and a projection display device including a projection lens that projects the image, wherein the illumination system has a plurality of laser light sources arranged in a matrix. A coupling optical system in which a plurality of light emitting points of the laser light source correspond to one lens, an optical fiber array corresponding to one optical fiber, and a condensing optical system corresponding to one lens,
A projection display device comprising a polarization conversion optical system that separates the light from the light collecting optical system into respective polarization directions. 8. An illumination system that generates red light, green light, and blue light, a two-dimensional light modulator that modulates light output from the illumination system according to image information to form an optical image, Red light, green light, a dichroic prism that synthesizes an image corresponding to blue light, and a projection display device including a projection lens that projects the image, in the illumination system, a plurality of laser light sources arranged in a line and A coupling optical system in which the linear light emitting points of the solid-state light source correspond to one lens, an optical fiber array in which one optical fiber corresponds, and a condensing optical system in which one lens corresponds to a plurality of optical fibers. And a polarization conversion optical system that separates light from the light collection optical system into respective polarization directions.