JP7329731B2 - Light source device and projection display device - Google Patents

Description

The present disclosure relates to a projection display device that irradiates an image formed on an image forming element with illumination light and projects the enlarged image onto a screen through a projection lens.

A light source device that uses long-life solid-state light sources such as semiconductor lasers and light-emitting diodes as light sources for projection display devices that use image forming elements such as mirror-deflection type digital micromirror devices (DMDs) and liquid crystal panels. are numerously disclosed. Among them, a light source device with a wide color gamut and high efficiency using blue, green, and red laser light sources is disclosed (see Patent Document 1).

When an image is formed on a screen using highly coherent laser light, speckle noise occurs on the screen. This speckle noise is a random interference pattern generated by the interference of laser light reflected from a screen having fine unevenness, and is observed as a pattern of bright and dark spots.

A conventional light source device consists of blue, green, and red laser light sources, a small dichroic mirror that synthesizes the condensed light from the laser light sources, a transmissive rotating diffuser plate, and a diffuser plate placed in front of the rotating diffuser plate. , while eliminating speckle noise and minute luminance unevenness, a compact light source device is constructed.

JP 2019-40177 A

The present disclosure uses blue, green, and red laser light sources to eliminate speckle noise and minute luminance unevenness in projected images, and provides a compact, highly efficient light source device, and a projection display using the light source device. Provide equipment.

The light source device of the present disclosure includes blue, green, and red laser light sources, a polarizing beam splitter that separates and synthesizes the linearly polarized blue, green, and red laser lights from the blue, green, and red laser light sources, and a polarizing beam splitter. A retardation plate that converts the transmitted light into circularly polarized light, a dynamic diffusion plate that diffuses the blue, green, and red laser light that has passed through the retardation plate, and a third diffuser that reflects the laser light diffused by the dynamic diffusion plate. It has one reflective element and a second reflective element that reflects the light reflected by the polarization beam splitter.

According to the present disclosure, it is possible to provide a compact, highly efficient light source device with a wide color gamut while eliminating speckle noise in a projected image. Furthermore, a compact and highly efficient projection display device with a wide color gamut that eliminates speckle noise can be realized.

Configuration diagram of a light source device according to Embodiment 1 of the present disclosure FIG. 4 shows spectral characteristics of the polarization beam splitter according to Embodiment 1; FIG. 4 is a diagram showing spectral characteristics of the polarization beam splitter with respect to the incident angle according to Embodiment 1; Ray diagram in the first reflective element Configuration diagram of a projection display device according to Embodiment 2 of the present disclosure Configuration diagram of a projection display device according to Embodiment 3 of the present disclosure

Hereinafter, embodiments for implementing the present disclosure will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a configuration diagram of a light source device according to Embodiment 1 of the present disclosure.

The light source device 44 includes a green laser light source 22 composed of a green semiconductor laser substrate 20 on which a plurality of green semiconductor laser elements are arranged and a collimating lens array 21, and a red semiconductor laser substrate 24 on which a plurality of red semiconductor laser elements are arranged and a collimating lens array 25. and a blue laser light source 30 consisting of a blue semiconductor laser substrate 28 on which a plurality of blue semiconductor laser elements are arranged and a collimator lens array 29 . A heat sink 23 is attached to the green laser light source 22 , a heat sink 27 is attached to the red laser light source 26 , and a heat sink 31 is attached to the blue laser light source 30 . The light source device 44 also includes a red-reflecting dichroic mirror 32, a blue-reflecting dichroic mirror 33, a diffusion plate 34, a polarizing beam splitter 35, an optical thin film 36 of the polarizing beam splitter, a retardation plate 37 which is a quarter-wave plate, A condenser lens 38, a rotating diffuser plate 41 which is a dynamic diffuser plate and is composed of a circular diffuser plate 39 and a motor 40, a first reflecting mirror 42 which is a first reflecting element, and a second mirror which is a second reflecting element. Two reflecting mirrors 43 are provided.

The drawing shows the polarization directions of the light emitted from the laser light source and the light incident on and emitted from the red-reflecting dichroic mirror 32 , the blue-reflecting dichroic mirror 33 , and the polarization beam splitter 35 . That is, in FIG. 1, the serpent's eye symbol indicates S-polarized light, the double-headed arrow symbol indicates P-polarized light, and the up, down, left, and right arrows along with the symbols indicating these polarizations indicate the direction of travel of the polarized light.

The green laser light source 22 comprises a green semiconductor laser substrate 20 on which 24 (6×4) green semiconductor laser elements are two-dimensionally arranged at regular intervals, and a collimator lens array 21 . The green semiconductor laser substrate 20 emits green light with a wavelength width of 525±8 nm and emits linearly polarized light. The lights emitted from the green semiconductor laser substrate 20 are respectively condensed by the corresponding collimate lens array 21 and converted into parallel light beams. The radiator plate 23 cools the green semiconductor laser substrate 20 .

The red laser light source 26 comprises a red semiconductor laser substrate 24 on which 24 (6×4) red semiconductor laser elements are two-dimensionally arranged at regular intervals, and a collimator lens array 25 . The red semiconductor laser substrate 24 emits red light with a wavelength width of 640±8 nm and emits linearly polarized light. The light emitted from the red semiconductor laser substrate 24 is condensed by the corresponding collimator lens array 25 and converted into parallel light beams. The radiator plate 27 is for cooling the red semiconductor laser substrate 24 .

The blue laser light source 30 comprises a blue semiconductor laser substrate 28 on which eight (2×4) blue semiconductor laser elements are two-dimensionally arranged at regular intervals, and a collimator lens array 29 . The blue semiconductor laser substrate 28 emits blue light with a wavelength width of 465±8 nm and emits linearly polarized light. Blue semiconductor lasers have a higher luminous efficiency than red and green semiconductor lasers, and the light output required for desired white light chromaticity is small. The light emitted from the blue semiconductor laser substrate 28 is condensed by the corresponding collimator lens array 29 and converted into parallel light beams. The radiator plate 31 is for cooling the blue semiconductor laser substrate 28 .

The laser beams from the green laser light source 22 and the red laser light source 26 are P-polarized, respectively, and enter the red-reflecting dichroic mirror 32 . The red-reflecting dichroic mirror 32 has a characteristic of transmitting 95% or more of the green laser light and reflecting 97% or more of the red laser light at an incident angle of 45 degrees. The half-value wavelength at which the transmittance is 50% is 583 nm for P-polarized light. The green laser light and the red laser light are synthesized by a red-reflecting dichroic mirror 32 and then enter a blue-reflecting dichroic mirror 33 . The blue-reflecting dichroic mirror 33 has a characteristic of transmitting 95% or more of red laser light and green laser light and reflecting 97% or more of blue laser light at an incident angle of 45 degrees. The half-value wavelength at which the transmittance is 50% is 495 nm for P-polarized light. The laser light from the blue laser light source 30 is P-polarized and enters the blue reflecting dichroic mirror.

Blue, green, and red laser beams synthesized by the red-reflecting dichroic mirror 32 and the blue-reflecting dichroic mirror 33 are incident on the diffusion plate 34 . The diffusion plate 34 has a diffusion surface formed by forming an array of fine microlenses on a glass substrate, and diffuses incident light. By making the diffusing surface microlens-shaped, it is possible to reduce the maximum divergence angle compared to chemically treated diffusing plates in which the glass surface is processed into fine irregularities using a solution such as hydrofluoric acid, and thus diffusion loss can be reduced. . The diffusion angle, which is the half-value angle width at 50% of the maximum intensity of the diffused light, is as small as about 2 degrees, and the polarization characteristics are maintained. The light from the diffusion plate 34 is incident on the polarization beam splitter 35 at an angle of 0±5 degrees or less due to the light emission spread and diffusion of the laser light. The diffusing plate 34 reduces the light intensity density of the laser light that passes through the polarization beam splitter 35, and suppresses the decrease in birefringence and transmittance due to the local temperature rise.

The polarizing beam splitter 35 is a prism-type polarizing beam splitter in which two rectangular prisms are optically bonded without using an adhesive containing an organic material. Quartz glass is used for the prism. An optical thin film 36 is formed on the cemented surface of one prism. The incident angle of light to the optical thin film 36 is 45 degrees. Optical bonding of prisms is more costly than a polarizing beam splitter using adhesive, but it has excellent light resistance and heat resistance, and since the adhesive does not deteriorate over time, long-term reliability can be ensured. By using quartz glass for the prism, it has excellent light resistance and heat resistance, and does not cause birefringence or decrease in transmittance due to local heating of the prism due to laser light. and can be synthesized.

FIG. 2 shows spectral transmittance characteristics of the polarizing beam splitter. The spectral transmittance characteristics of P-polarized light and S-polarized light at an incident angle of 45 degrees are shown. The polarizing beam splitter 35 has a characteristic of transmitting P-polarized light at a wavelength of 420 nm to 700 nm with a transmittance of 98% or more. In the case of S-polarized light, the transmittance is 2% or less at wavelengths of 420 nm to 700 nm, which is a characteristic of reflecting 98% or more of light. The spectral characteristics of FIG. 2 are an example of designing the optical thin film 36 formed on the cemented surface of the prism by alternately forming 69 layers of aluminum oxide AL2O3 with a refractive index of 1.63 and magnesium fluoride MgF2 with a refractive index of 1.38. is.

FIG. 3 shows spectral transmittance characteristics with respect to the incident angle of the polarizing beam splitter. The transmittance of P-polarized light and S-polarized light at an incident angle of 45°±3.4° to the surface of the optical thin film 36 is shown. The angle ±3.4 degrees is the angle in the glass medium, and the converted angle in the air is ±5 degrees. In the case of S-polarized light, the change in transmittance for 45-degree incidence is as small as 2% or less, but in the case of P-polarized light, the decrease in transmittance with respect to the incident angle is large. At a blue laser light wavelength of 465 nm, a green laser light wavelength of 525 nm, and a red laser light wavelength of 640 nm, the P-polarized light transmittances at 45-degree incidence and 41.6-degree incidence are 12.8%, 8.8%, and 5%, respectively. .3% lower. Also, the P-polarized light transmittance for 48.4-degree incidence decreases by 4.2%, 0.6%, and 0.6%, respectively.

The P-polarized blue, green, and red laser beams pass through the polarizing beam splitter 35 with high efficiency. However, when the amount of change in the incident angle for P-polarized light increases, the amount of light reflected by the polarizing beam splitter 35 increases.

The P-polarized blue, green, and red laser beams are incident on the retardation plate 37 after passing through the polarization beam splitter 35 . The retardation plate 37 is a broadband 1/4 wavelength plate having a retardation of about 1/4 wavelength between 440 nm and 680 nm, and is composed of a thin film retardation plate utilizing birefringence due to oblique vapor deposition. When the P polarization direction in the figure is 0 degree, the optical axis of the retardation plate 37 is arranged at 45 degrees. The retardation plate 37 converts the P-polarized light into circularly polarized light. The circularly polarized light enters the condenser lens 38 and is condensed. Light condensed from the condenser lens 38 is incident on the first reflecting mirror 42 after passing through the rotating diffuser plate 41 . The focal length of the condenser lens 38 is set so that the condensing angle is 40 degrees or less to form a condensed spot near the first reflecting mirror 42 . The rotating diffuser plate 41 is provided with a circular diffuser plate 39 having a diffusion layer formed on one surface of a glass substrate and a motor 40 in the center thereof, and the rotation can be controlled. A rotating diffusion plate is a diffusion plate that can rotate at high speed up to about 10,800 rpm. A chemically treated diffuser plate is used for the diffusion of the circular diffuser plate 39, and the diffusion angle is approximately 10 degrees to maintain the polarization characteristics.

FIG. 4 shows the appearance of light rays on the first reflecting mirror. The first reflecting mirror 42 is formed by forming a dielectric multilayer film with a reflectance of 30% on one side of a glass substrate having a thickness of 1.0 mm, and forming a dielectric multilayer film with a reflectance of 99% or more on the other side. It is a multiple reflection mirror with a multilayer film. A light ray 45 incident on the first reflecting mirror 42 is divided into a group of light rays 46 due to multiple reflections by the first reflecting mirror 42 . FIG. 4 shows the appearance of the light until it is divided into six. Assuming that the incident light intensity is 100%, the respective light beam intensities in the six divisions are 30%, 48.5%, 14.4%, 4.3%, 1.3%, and 0.4% in order of the number of reflections. becomes emitted. The size of the group of split rays depends on the refractive index and thickness of the glass substrate. The multiple reflections equivalently increase the emission size of the laser light and increase the number of emission.

The light reflected by the first reflecting mirror 42 has its phase reversed, becomes diverging light as circularly polarized light in the opposite direction, diffuses again and passes through the rotary diffuser plate 41, and is condensed by the condenser lens 38 to become parallel light. is converted to The light converted into parallel light passes through the retardation plate 37 and is converted into S-polarized light. The S-polarized light converted by the retardation plate 37 is reflected by the polarizing beam splitter 35 . As shown in FIG. 3, S-polarized light has a small change in spectral characteristics with respect to the incident angle, and even light with a large degree of diffusion is reflected with a high reflectance.

The random interference pattern on the screen caused by the laser beam changes at high speed temporally and spatially due to the rotating diffuser plate and the multi-reflecting mirror, which transmit the light multiple times, and the speckle noise can be eliminated. In addition, it is possible to reduce minute unevenness in luminance caused by the minute size and number of light emission of the laser light source.

On the other hand, the P-polarized light reflected by the polarization beam splitter 35 enters the second reflecting mirror 43 due to the change in the spectral characteristics with respect to the incident angle. As with the first reflecting mirror 42, the second reflecting mirror 43 is formed by forming a dielectric multilayer film having a reflectance of 30% on one surface of a glass substrate having a thickness of 1.0 mm and forming a dielectric multilayer film on the other surface. It is a multiple reflection mirror formed with a dielectric multilayer film having a reflectance of 99% or more. Similar to the first reflecting mirror 42 shown in FIG. 4, the incident light beam is divided into many parts and reflected. Multiple reflected light maintains its polarization.

The P-polarized light split by the second reflecting mirror 43 reenters the polarizing beam splitter 35 and passes therethrough. When the incident angle of the polarizing beam splitter 35 to the optical thin film 36 is 41.6 degrees, the light reflected by the polarizing beam splitter 35 is reflected by the second reflecting mirror 43 and enters the optical thin film 36 again. The light is converted to 48.4 degree incidence, and the spectral transmittance characteristics are enhanced. The light reflected from the polarization beam splitter 35 by the second reflecting mirror 43 is multiple-reflected by the second reflecting mirror and becomes effective light emitted from the light source device 44 .

In this way, one of the blue, green, and red laser beams transmitted through the polarizing beam splitter is multiple-reflected by the first reflecting mirror after passing through the rotating diffuser plate, becomes S-polarized light, and is reflected by the polarizing beam splitter. . The other blue, green, and red laser beams reflected by the polarizing beam splitter are multiple-reflected by the second reflecting mirror and then pass through the polarizing beam splitter. The S-polarized light and the P-polarized light combined by the polarization beam splitter exit the polarization beam splitter 35 . The emitted light becomes white light from which speckle noise has been eliminated.

Although the polarizing beam splitter 35 is made of silica glass, other optical glass may be used if the birefringence level of the polarizing beam splitter due to laser light is small, which does not cause a drop in the efficiency of polarization splitting and synthesis. The cost of the polarizing beam splitter can be reduced by using other optical glasses.

Although the diffuser plate 34 is arranged, the diffuser plate may not be arranged when the birefringence level of the polarization beam splitter for laser light is small. In this case, the spread of the angle of incidence on the polarizing beam splitter becomes small, and polarization separation and synthesis can be performed with high efficiency.

Although the retardation plate 37 is arranged between the polarizing beam splitter 35 and the condenser lens 38, if it is between the polarizing beam splitter 35 and the first reflecting mirror 42, linearly polarized light can be changed to circularly polarized light, or Since circularly polarized light can be converted into linearly polarized light, it can be arranged in either direction.

The rotating diffuser plate 41 may be a circular diffuse reflector having a diffuser layer formed on one surface of a circular glass substrate and a reflective layer formed on the other surface, and a motor in the center. This reflective layer serves as the first reflective element, and the rotating diffuser plate is a combination of the dynamic diffuser plate and the first reflective element. In this case, the arrangement of the first reflecting mirror 42 shown in FIG. 1 becomes unnecessary, and the size can be further reduced. The reflective layer of the circular diffuse reflector is formed of a dielectric multilayer film and reflects blue, green, and red laser beams with high reflectance. The circular diffuse reflector does not have multiple reflections, but the rotation of the diffuser surface causes the random interference pattern on the screen caused by the laser light to fluctuate at high speed in time and space, eliminating speckle noise. can be done. In addition, it is possible to reduce minute unevenness in luminance caused by the minute size and number of light emission of the laser light source.

As the dynamic diffusion plate, instead of the rotating diffusion plate, a swinging diffusion plate or a vibration diffusion plate that oscillates or vibrates temporally and spatially may be used.

The green laser light source, the red laser light source, and the blue laser light source are arranged with 24, 24, and 8 semiconductor laser elements, respectively. may be configured using

Blue, green, and red laser light sources are composed of blue, green, and red semiconductor laser elements as one group, and single or multiple groups are formed on one substrate. You may use the laser light source of the structure which carries out. In this case, since the laser light source emits blue, green, and red light, a plurality of dichroic mirrors for synthesizing blue, green, and red laser light are not required, and a more compact light source device can be configured.

A condenser lens and a diffusion plate may be arranged between the polarizing beam splitter and the second reflecting mirror. By arranging the condenser lens and the diffuser plate, the multiple reflected light can be diffused and condensed, so speckle noise can be further reduced without lowering the efficiency.

As described above, the polarizing beam splitter, the dynamic diffusion plate, and the first reflecting mirror form a compact light source device to reduce speckle noise. In addition, the second reflecting mirror can efficiently convert the light that is lost by being reflected by the polarization beam splitter into effective light with reduced speckle noise. Therefore, it is possible to construct a light source device that is compact, highly efficient, and has a wide color gamut while eliminating speckle noise and minute luminance unevenness.
(Embodiment 2)
FIG. 5 shows a first projection display device according to Embodiment 3 of the present disclosure. As an image forming element, a TN mode or VA mode active matrix transmissive liquid crystal panel in which thin film transistors are formed in a pixel region is used. The light source device 44 is the light source device shown in Embodiment 1 of the present disclosure.

The first projection display device includes a first lens array plate 200, a second lens array plate 201, a polarization conversion element 202, a superimposing lens 203, a blue reflecting dichroic mirror 204, a green reflecting dichroic mirror 205, and a reflecting light. Mirrors 206, 207, 208, relay lenses 209, 210, field lenses 211, 212, 213, incident side polarizers 214, 215, 216, liquid crystal panels 217, 218, 219, output side polarizers 220, 221, 222, red A color synthesizing prism 223 composed of a reflecting dichroic mirror and a blue reflecting dichroic mirror and a projection lens 224 are provided. Here, the pixel area of the liquid crystal panel is an example of the area to be illuminated, and the first lens array plate 200, the second lens array plate 201, the polarization conversion element 202, and the superimposing lens 203 collect light from the light source device. It is an example of an illumination optical system that illuminates a region to be illuminated.

Blue, green, and red lights emitted from the light source device 44 enter the first lens array plate 200 composed of a plurality of lens elements. A light beam incident on the first lens array plate 200 is split into a large number of light beams. A large number of split light beams converge on a second lens array plate 201 composed of a plurality of lenses. The lens elements of the first lens array plate 200 have aperture shapes similar to those of the liquid crystal panels 217 , 218 and 219 . The focal lengths of the lens elements of the second lens array plate 201 are determined so that the first lens array plate 200 and the liquid crystal panels 217, 218 and 219 are in a substantially conjugate relationship. The split light from the second lens array plate 201 enters the polarization conversion element 202 . The polarization conversion element 202 is composed of a polarization separation prism and a half-wave plate. The polarization conversion element 202 converts incident P-polarized light into S-polarized light, and emits incident S-polarized light as S-polarized light. The light emitted from the polarization conversion element 202 enters the superimposing lens 203 . The superimposing lens 203 is a lens for superimposing and illuminating the liquid crystal panels 217 , 218 and 219 with the light emitted from each lens element of the second lens array plate 201 . Light from the superimposing lens 203 is separated into blue, green, and red colored lights by a blue-reflecting dichroic mirror 204 and a green-reflecting dichroic mirror 205, which are color separating means. The green light passes through the field lens 211 and the incident side polarizing plate 214 and enters the liquid crystal panel 217 . After being reflected by the reflecting mirror 206 , the blue light is transmitted through the field lens 212 and incident side polarizing plate 215 and enters the liquid crystal panel 218 . The red light is transmitted, refracted and reflected by relay lenses 209 and 210 and reflection mirrors 207 and 208 , passes through field lens 213 and incident side polarizing plate 216 , and enters liquid crystal panel 219 . The three liquid crystal panels 217, 218, and 219 change the polarization state of incident light by controlling the voltage applied to the pixels according to the video signal, and the transmission axes are orthogonal to both sides of each liquid crystal panel 217, 218, and 219. The respective input side polarizers 214, 215, 216 and the output side polarizers 220, 221, 222 arranged in such a way are combined to modulate the light to form green, blue and red images. The colored lights transmitted through the exit-side polarizing plates 220, 221, and 222 are reflected by a red-reflecting dichroic mirror and a blue-reflecting dichroic mirror, respectively, by a color synthesizing prism 223, and combined with the green light. , enter the projection lens 224 . The light incident on the projection lens 224 is enlarged and projected onto a screen (not shown).

The image forming means uses three liquid crystal panels that use polarized light instead of a time-division method, so that there is no color breaking and color reproduction is good, and a bright and high-definition projected image can be obtained. In addition, compared to the case of using three DMD elements, a total reflection prism is not required, and the prism for color synthesis is a small prism with 45-degree incidence.

As described above, the first projection display device of the present disclosure configures a compact optical system with blue, green, and red laser light sources, a polarizing beam splitter, a dynamic diffusion plate, and a first reflecting mirror. At the same time, a light source device is used that eliminates speckle noise and converts the light that is reflected and lost by the polarization beam splitter into effective light with speckle noise eliminated by the second reflecting mirror. Therefore, it is possible to construct a compact and highly efficient projection display device while eliminating speckle noise and luminance unevenness.

Although a transmissive liquid crystal panel is used as the image forming means, a reflective liquid crystal panel may be used. By using a reflective liquid crystal panel, a smaller, higher-definition projection display device can be constructed.
(Embodiment 3)
FIG. 6 shows a second projection display device according to a third embodiment of the present disclosure. Three DMDs are used as image forming means. The light source device is the light source device 44 shown in the first embodiment of the present disclosure. The second projection display device includes a condenser lens 300, a rod 301, a relay lens 302, a reflecting mirror 303, a field lens 304, a total reflecting prism 305, an air layer 306, a blue reflecting dichroic mirror 308, and a red reflecting dichroic mirror 309. A color prism 307, DMDs 310, 311 and 312, and a projection lens 313 are provided. Here, the DMDs 310, 311, and 312 are examples of pixel forming elements.

Blue, green, and red lights emitted from the light source device 44 are condensed onto the rod 301 by the condenser lens 300 . The light incident on the rod 301 is reflected multiple times inside the rod, so that the light intensity distribution is made uniform and the light is emitted. Light emitted from the rod 301 is collected by a relay lens 302 , reflected by a reflecting mirror 303 , transmitted through a field lens 304 , and incident on a total reflection prism 305 . The total reflection prism 305 is composed of two prisms, and a thin air layer 306 is formed between adjacent surfaces of the prisms. Air layer 306 totally reflects light incident at an angle equal to or greater than the critical angle. Light from the field lens 304 is reflected by the total reflection surface of the total reflection prism 305 and enters the color prism 307 . The color prism 307 is composed of three prisms, and a blue-reflecting dichroic mirror 308 and a red-reflecting dichroic mirror 309 are formed on the proximal surface of each prism. The blue, red, and green lights are separated by the blue-reflecting dichroic mirror 308 and the red-reflecting dichroic mirror 309 of the color prism 307, and enter DMDs 310, 311, and 312, respectively. The DMDs 310 , 311 , and 312 deflect the micromirrors according to the video signal and reflect the light incident on the projection lens 313 and the light traveling outside the projection lens 313 . The area where the micromirrors are arranged in the DMDs 310, 311, and 312 to reflect the light is an example of the area to be illuminated. is an example of an illumination optical system for condensing and illuminating a region to be illuminated. Light reflected by DMDs 310 , 311 , and 312 passes through color prism 307 again. In the process of passing through the color prism 307 , the separated blue, red, and green lights are synthesized and enter the total reflection prism 305 . Since the light incident on the total reflection prism 305 enters the air layer 306 at an angle less than the critical angle, it is transmitted and enters the projection lens 313 . In this manner, image light formed by DMDs 310, 311, and 312 is enlarged and projected onto a screen (not shown).

Since the DMD is used as the image forming element, a projection display device having high light resistance and heat resistance can be constructed as compared with image forming means using liquid crystal. Furthermore, since three DMDs are used, it is possible to obtain a bright and high-definition projected image with excellent color reproduction.

As described above, the second projection display device of the present disclosure constitutes a compact optical system with the blue, green, and red laser light sources, the polarizing beam splitter, the dynamic diffusion plate, and the first reflecting mirror. At the same time, a light source device is used that eliminates speckle noise and converts the light that is reflected and lost by the polarization beam splitter into effective light with speckle noise eliminated by the second reflecting mirror. Therefore, it is possible to construct a compact and highly efficient projection display device while eliminating speckle noise and luminance unevenness.

The present disclosure relates to a projection display device using an image forming element.

20 green semiconductor laser substrates 21, 25, 29 collimator lens array 22 green laser light sources 23, 27, 31 heat sink 24 red semiconductor laser substrate 26 red laser light source 28 blue semiconductor laser substrate 30 blue laser light sources 32, 309 red reflecting dichroic mirror 33, 204, 308 Blue reflecting dichroic mirror 34 Diffusion plate 35 Polarization beam splitter 36 Optical thin film 37 Retardation plate 38, 300 Condenser lens 39 Circular diffusion plate 40 Motor 41 Rotary diffusion plate 42 First reflection mirror 43 Second reflection Mirror 44 Light source device 45 Light ray 46 Light ray group 200 First lens array plate 201 Second lens array plate 202 Polarization conversion element 203 Superimposing lens 205 Green reflecting dichroic mirrors 206, 207, 208, 303 Reflecting mirrors 209, 210, 302 relay lenses 211, 212, 213, 304 field lenses 214, 215, 216 incident side polarizers 217, 218, 219 liquid crystal panels 220, 221, 222 exit side polarizers 223 color synthesis prisms 224, 313 projection lens 301 rod 305 all Reflecting prism 306 Air layer 307 Color prisms 310, 311, 312 DMD

Claims (13)

blue, green and red laser light sources;
a polarizing beam splitter that separates linearly polarized blue, green, and red laser light from the blue, green, and red laser light sources by transmitting or reflecting the laser light based on the polarization direction ;
a retardation plate that converts one of the lights transmitted through the polarizing beam splitter into circularly polarized light;
a dynamic diffusion plate that diffuses the blue, green, and red laser beams that have passed through the retardation plate;
a first reflecting element that reflects the laser light diffused by the dynamic diffusion plate;
a second reflecting element that reflects the other light reflected by the polarizing beam splitter ;
The light source device , wherein the light reflected by the first reflecting element and the light reflected by the second reflecting element are synthesized by the polarization beam splitter. 2. A light source device according to claim 1, wherein said polarizing beam splitter is a prism-type polarizing beam splitter optically bonded without using an adhesive. 2. A light source device according to claim 1, wherein said polarizing beam splitter is a prism-type polarizing beam splitter composed of quartz glass prisms. 2. The light source device according to claim 1, wherein said retardation plate is a quarter-wave plate. 2. The light source device according to claim 1, wherein said retardation plate is arranged between the polarization beam splitter and the first reflecting element. 2. The light source device according to claim 1, wherein said dynamic diffusion plate is a rotary diffusion plate provided with a circular diffusion plate in which fine irregularities are circumferentially formed on one surface of a glass substrate and a motor. The dynamic diffusion plate is a circular diffusion reflection plate and a motor, which are formed by forming a fine uneven shape in a circular shape on one surface of a glass substrate and forming a reflection layer as a first reflection element on the other surface. 2. The light source device according to claim 1, which is a rotary diffusion plate provided with 2. The light source device according to claim 1, wherein said first reflecting element is a multiple reflection mirror. 2. The light source device according to claim 1, wherein said second reflecting element is a multiple reflection mirror. 2. A light source device according to claim 1, wherein said blue, green and red laser light sources are semiconductor lasers. a light source, an illumination optical system that collects light from the light source and illuminates an area to be illuminated, an image forming element that forms an image according to a video signal, and an image formed by the image forming element that is enlarged and projected. A projection display device comprising a projection lens, wherein the light source is the light source device according to claim 1 . 12. A projection display apparatus according to claim 11, wherein said image forming element is a liquid crystal panel. 12. A projection display apparatus according to claim 11, wherein said image forming element is a mirror deflection type digital micromirror device (DMD).

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