CN107608166B

CN107608166B - Light source device and projection display device

Info

Publication number: CN107608166B
Application number: CN201710519311.2A
Authority: CN
Inventors: 田中孝明; 奥野学
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2016-07-12
Filing date: 2017-06-29
Publication date: 2022-08-16
Anticipated expiration: 2037-06-29
Also published as: JP2022093391A; JP6893298B2; CN114721213A; PH12017000156B1; CN107608166A; PH12017000156A1; JP7108828B2; JP2018013764A; JP2021120757A; JP7312944B2

Abstract

A light source device using a low-cost retardation plate having excellent durability by utilizing polarization characteristics of light emitted from a solid-state light source and a projection display device using the light source device are provided. In the light source device (40), P-polarized blue light emitted from a semiconductor laser (21) passes through a condenser lens (23), a lens (26), a lens (27), and a 1 st diffuser plate (28) and enters a dichroic mirror (29). The dichroic mirror (29) transmits a part of the P-polarized blue light and reflects the remaining light. The blue light transmitted through the dichroic mirror (29) is condensed by a condenser lens (36) to become a condensed light, and is transmitted through a quarter-wave plate (38) to enter a reflection plate (39). The blue light reflected by the reflector and converted into diverging light passes through the quarter-wave plate (38) and is incident on the condenser lens (36) to be converted into parallel light.

Description

Light source device and projection display device

Technical Field

The present invention relates to a projection display device that irradiates an image formed on a small bulb with illumination light and performs enlarged projection on a screen through a projection lens.

Background

As a light source of a projection display device using a bulb of a mirror deflection type Digital Micromirror Device (DMD) or a liquid crystal panel, many light source devices using a long-life semiconductor laser or a solid-state light source of a light emitting diode are disclosed. Among them, patent document 1 discloses a light source device that is small and efficiently collects light from a solid-state light source by utilizing polarization characteristics of light emitted from the solid-state light source.

Patent document 2 discloses a small and efficient light source device using a half-wave plate that converts the polarization direction of light from a fixed light source and controls the P-polarization component and the S-polarization component incident on a dichroic mirror to a constant ratio.

Prior art documents

Patent document

Patent document 1: JP 2012-137744

Patent document 2: JP patent application publication 2014-209184

Disclosure of Invention

The invention provides a light source device using a retardation plate having excellent durability and low cost by utilizing polarization characteristics of light emitted from a solid-state light source, and a projection display device using the light source device.

The 1 st light source device of the present invention includes: a solid state light source; a light-condensing element for condensing light from the solid-state light source; a phase difference plate for converting linearly polarized light into circularly polarized light; and a reflection plate, the phase difference plate being disposed between the light collecting element and the reflection plate, at a position where the convergent light or the divergent light enters.

Further, a 2 nd light source device according to the present invention includes: a solid state light source; a phase difference plate for converting the polarization direction of the light from the solid-state light source and controlling the light of P polarization and S polarization components to a certain ratio; and a dichroic mirror for separating the light from the phase difference plate by polarization, wherein the phase difference plate is disposed between the solid-state light source and the dichroic mirror at a position where the convergent light or the divergent light enters.

Effects of the invention

According to the present invention, since the phase difference plate is disposed at the position where light is condensed, a small and inexpensive light source device can be configured, and thus a projection display device having a long life, brightness, and low cost can be realized.

Drawings

Fig. 1 is a configuration diagram of a light source device in embodiment 1 of the present invention.

Fig. 2 is a diagram showing spectral characteristics of the dichroic mirror in embodiment 1.

Fig. 3 is a diagram showing the angle-dependent characteristic of the polarization transmittance of the retardation plate.

Fig. 4 is a configuration diagram of a light source device in embodiment 2 of the present invention.

Fig. 5 is a diagram showing spectral characteristics of a dichroic mirror in embodiment 2.

Fig. 6 is a configuration diagram of a projection display device according to embodiment 3 of the present invention.

Fig. 7 is a configuration diagram of a projection display apparatus according to embodiment 4 of the present invention.

Description of the symbols

21. 51 semiconductor laser

22. 52 heat sink

23. 53 condenser lens

24. 54 heat sink

25. 55 light beam

26. 27 lens

28. 60 No. 1 diffusion plate

29. 61 dichroic mirror

30. 31, 36, 56, 59, 62, 63, 68 condenser lens

32. 64 phosphor layer

33. 65 aluminum substrate

34. 66 electric motor

35. 67 fluorescent screen

37. 69 nd 2 diffusion plate

38 quarter wave plate

39. 71 reflecting plate

40. 72 light source device

57 reflector

58 half wave plate

70 quarter wave plate

80. 90 projection display device

100 light-gathering lens

101 rod

102. 209, 210 relay lens

103. 206, 207, 208 mirror

104. 211, 212, 213 field lens

105 total reflection prism

106 layer of air

107 color prism

108. 204 blue reflective dichroic mirror

109 red reflection dichroic mirror

110、111、112 DMD

113. 224 projection lens

200 st lens array plate

201 nd 2 nd lens array plate

202 polarization conversion element

203 lens for superposition

205 green reflection dichroic mirror

214. 215, 216 incident side polarizing plate

217. 218, 219 liquid crystal panel

220. 221, 222 emission side polarizing plate

223 color synthesis prism

Detailed Description

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings as appropriate. However, too detailed description may be omitted. For example, detailed descriptions of already known matters and repetitive descriptions of substantially the same configuration may be omitted. This is to avoid the following description becoming too lengthy to allow those skilled in the art to understand it easily.

In addition, the drawings and the following description are provided for those skilled in the art to sufficiently understand the present invention, and it is not intended to limit the subject matter described in the claims by these contents.

(embodiment mode 1)

Fig. 1 is a configuration diagram of a light source device according to embodiment 1 of the present invention. The light source device 40 of embodiment 1 includes: the light source device includes a semiconductor laser 21 as a solid-state light source, a heat radiation plate 22, a condenser lens 23, a heat radiation fin 24, a lens 26, a lens 27, a 1 st diffuser plate 28, a dichroic mirror 29,

condenser lenses

30 and 31 as 1 st condenser elements, a phosphor plate 35 composed of an aluminum substrate 33 on which a reflective film and a phosphor layer 32 are formed and a motor 34, a condenser lens 36 as a 2 nd condenser element, a 2 nd diffuser plate 37, a quarter wave plate 38 as a retardation plate, and a reflector plate 39. Fig. 1 shows the state of each light beam 25 emitted from the solid-state light source and the polarization direction of light entering and exiting the dichroic mirror 29.

24 (6 × 4) semiconductor lasers 21 and condenser lenses 23 are arranged in a rectangular shape on a heat radiation plate two-dimensionally at a fixed interval. The heat sink 24 is used to cool the semiconductor laser 21. The semiconductor laser 21 emits blue light having a wavelength width of 447 to 462nm and emits linearly polarized light. Each semiconductor laser is arranged so that the polarized light emitted from the semiconductor laser 21 is P-polarized with respect to the incident surface of the dichroic mirror 29.

The light emitted from the plurality of semiconductor lasers 21 is condensed by the corresponding condenser lenses 23 and converted into parallel light fluxes 25. The light flux 25 group is further reduced in diameter by the convex lens 26 and the concave lens 27, and enters the 1 st diffusion plate 28. The 1 st diffusion plate 28 is made of glass, and diffuses light by fine irregularities on the surface. The diffusion angle, which is a half-value angular width of 50% of the maximum intensity of the diffused light, is as small as about 3 degrees, and the polarization characteristics are maintained. The light emitted from the 1 st diffusion plate 28 enters the dichroic mirror 29.

The spectral characteristics of the dichroic mirror are shown in fig. 2. The spectral characteristics show the transmittance with respect to the wavelength. The dichroic mirror has spectral characteristics such that P-polarized semiconductor laser light having a wavelength of 447 to 462nm is transmitted at a constant rate (average 18%) and reflected (average 82%) and S-polarized semiconductor laser light is reflected at a high reflectance of 95% or more. Further, both P-polarization and S-polarization of green light and red light transmit light at a high transmittance of 96% or more.

82% of the P-polarized blue light reflected by the dichroic mirror 29 is condensed by the

condenser lenses

30 and 31, and when a diameter at which the light intensity becomes 13.5% with respect to the peak intensity is defined as a spot diameter, spot lights having a spot diameter of 1.5mm to 2.5mm are superimposed and incident on the fluorescent plate 35. The 1 st diffusion plate 28 diffuses the light so that the diameter of the spot light becomes a desired diameter.

The phosphor plate 35 is a circular substrate that can be controlled to rotate and includes an aluminum substrate 33 on which a reflective film and a phosphor layer 32 are formed and a motor 34 at the center. The reflective film of the fluorescent plate 35 is a metal film or a dielectric film that reflects visible light, and is formed on the aluminum substrate. Further, a phosphor layer 32 is formed on the reflective film. The phosphor layer 32 is formed with a Ce-activated YAG yellow phosphor that emits yellow light including green and red components when excited by blue light. A typical chemical structure of the crystal matrix of the phosphor is Y ₃ Al ₅ O ₁₂ . The phosphor layer 32 is formed in an annular shape. The phosphor layer 32 excited by the spot light emits yellow light containing green and red components of light. The phosphor plate 35 is an aluminum substrate, and by rotating it, the temperature rise of the phosphor layer 32 due to the excitation light can be suppressed, and the fluorescence conversion efficiency can be stably maintained.

The light incident on the phosphor layer 32 fluoresces the color light of the green and red components and is emitted from the phosphor plate 35. The light emitted toward the reflective film is reflected by the reflective film and is emitted from the fluorescent plate 35. The green light and the red light emitted from the fluorescent plate 35 become natural light (unpolarized light), are condensed by the

condenser lenses

30 and 31 again, are converted into substantially parallel light, and then pass through the dichroic mirror 29.

On the other hand, 18% of the P-polarized blue light transmitted by the dichroic mirror 29 enters the condenser lens 36 as the 2 nd condensing element, and is condensed into convergent light. The focal length of the condenser lens 36 is set to a condensing angle of 40 degrees or less, and a condensing point is formed near the reflector 39. The condensed light condensed by the condenser lens 36 is incident on the 2 nd diffuser plate 37. The 2 nd diffusion plate 37 diffuses incident light, uniformizes light intensity distribution, and eliminates speckle of laser light. The 2 nd diffuser plate 37 has a diffusing surface formed of fine irregularities on the glass surface of the thin plate. The 2 nd diffusion plate 37 is a diffusion plate in which 1 st transmitted light on the diffusion surface has a diffusion angle of approximately 4 degrees and polarization characteristics are maintained. The light transmitted through the 2 nd diffusion plate 37 is incident on the quarter-wave plate 38 as a phase difference plate. The quarter-wave plate 38 is a phase difference plate whose phase difference is 1/4 in the vicinity of the emission center wavelength of the semiconductor laser 21.

In the case where the P-polarization direction in fig. 1 is set to 0 degrees, quarter-wave plate 38 arranges the optical axis at 45 degrees. The quarter-wave plate 38 is a thin film retardation plate utilizing birefringence due to oblique deposition of a dielectric material (see JP 2012-242449 a). The thin film retardation plate is made of an inorganic material and has excellent durability and reliability as well as inorganic optical crystals such as quartz. In addition, since the thin-film wavelength plate is formed by stacking thin films sufficiently thinner than the wavelength of light, the entire oblique deposition layer is a retardation plate having one optical axis. Therefore, the change in retardation with respect to the incident angle is very small as compared with a retardation plate of an inorganic optical crystal such as quartz crystal.

Fig. 3 shows an example of the angular dependence of the polarization transmittance in the thin film retardation plate (solid line) and the crystal retardation plate (broken line). The transmittance of one linearly polarized light component after linearly polarized light was made incident on the phase difference plate and converted into circularly polarized light was taken as the polarization transmittance, and the polarization transmittance with respect to the incident angle was shown. The polarization transmittance when the incident angle was 0 degrees was normalized to 1.0. The transmittance of the crystal retardation plate for polarized light at an incident angle of ± 5 degrees is reduced by 12%, while the transmittance of the crystal retardation plate for polarized light at an incident angle of ± 30 degrees is reduced by 6%. Since the thin film retardation plate has very small incident angle dependency, even if it is arranged at a position where convergent light or divergent light enters, it can efficiently convert incident linearly polarized light into circularly polarized light. Further, since the quarter-wave plate is disposed at a position where convergent light or divergent light enters, the size of the quarter-wave plate 38 can be reduced to a size of 1/2 or less, and the quarter-wave plate can be significantly reduced in cost, as compared with the case where the quarter-wave plate is disposed at a position where parallel light enters.

The light transmitted through the quarter-wave plate 38 and converted into circularly polarized light is phase-inverted by the reflection plate 39 formed with a reflection film such as aluminum or a dielectric multilayer film, and the circularly polarized light in the reverse direction becomes divergent light, and is converted into S-polarized light by transmitting through the quarter-wave plate 38. Further, since no member disturbing polarization is disposed between the quarter-wave plate 38 and the reflection plate 39, P-polarized light can be efficiently converted into S-polarized light.

The S-polarized light converted by the quarter wave plate 38 is diffused again by the 2 nd diffusion plate 37, converted into parallel light by the condenser lens 36, and reflected by the dichroic mirror 29.

Thus, the fluorescent light from the fluorescent plate 35 and the efficiently polarized blue light are combined by the dichroic mirror 29 and emitted as white light. The yellow light including green and red components emitted by fluorescence and the blue light of the semiconductor laser 21 provide excellent white-balance emission characteristics. Even if the light emission spectrum characteristics are separated into 3 primary colors of blue, green, and red by an optical system of the projection display device, monochromatic light with desired chromaticity coordinates can be obtained.

The quarter-wave plate was described using a thin-film retardation plate, but a microstructured retardation plate using birefringence due to a fine periodic structure equal to or smaller than the wavelength of light may be used. Since the microstructure phase difference plate has a microstructure equal to or smaller than the wavelength of light, the microstructure phase difference plate has a small incident angle dependency characteristic of the polarization transmittance, and can be arranged at a position where the convergent light is incident, as in the thin film phase difference plate shown in fig. 3.

As described above, the light source device of the present invention separates light from the plurality of semiconductor lasers by the dichroic mirror, and efficiently condenses and combines green light and red light, which are excited and emitted by one of the separated lights, and blue light, which is the other light polarized and converted by the small retardation plate disposed at the position where the condensed light is incident, to obtain white light.

(embodiment mode 2)

Fig. 4 is a configuration diagram of a light source device according to embodiment 2 of the present invention.

The light source device 72 of embodiment 2 includes: a semiconductor laser 51, a heat radiation plate 52, a condenser lens 53, a heat radiation fin 54,

condenser lenses

56, 59, a reflection mirror 57, a half wave plate 58 as a 1 st phase difference plate, a 1 st diffusion plate 60, a dichroic mirror 61,

condenser lenses

62, 63 as 1 st condensing elements, a fluorescent plate 67, a condenser lens 68 as a 2 nd condensing element, a 2 nd diffusion plate 69, a quarter wave plate 70 as a 2 nd phase difference plate, and a reflection plate 71. The figure shows the state of each light beam 55 emitted from the solid-state light source and the polarization direction of the light entering and exiting the dichroic mirror 61. The fluorescent plate 67 is composed of an aluminum substrate 65 on which a reflective film and a phosphor layer 64 are formed, and a motor 66.

The light source device 40 of embodiment 1 of the present invention has the same configuration as the semiconductor laser 51, the heat radiation plate 52, the condenser lens 53, the heat radiation plate 54, the 1 st diffuser 60, the

condenser lenses

62 and 63, the fluorescent plate 67, the condenser lens 68, the 2 nd diffuser 69, the quarter wave plate 70 as the 2 nd retardation plate, and the reflection plate 71.

24 (6 × 4) semiconductor lasers 51 and condenser lenses 53 arranged in a square shape are two-dimensionally arranged on a heat radiation plate 52 at a fixed interval. The heat sink 54 is used to cool the semiconductor laser 51. The semiconductor laser 51 emits blue light having a wavelength width of 447nm to 462nm and emits linearly polarized light. In fig. 4, the semiconductor lasers are arranged so that the polarized light emitted from the semiconductor laser 51 is P-polarized with respect to the incident surface of the dichroic mirror 61 without passing through the retardation plate. The light beams emitted from the plurality of semiconductor lasers 51 are condensed by the corresponding condenser lenses 53 and converted into parallel light beams 55. The group of light fluxes 55 is condensed by a convex condenser lens 56 and reflected by a mirror 57. The reflected converging light is condensed, and then becomes diverging light, and enters the half wave plate 58 as the 1 st phase difference plate. The incident angle of light to the half-wave plate 58 is 40 degrees or less. The half-wave plate 58 is a retardation plate whose phase difference is 1/2 in the vicinity of the emission center wavelength of the semiconductor laser 51. The half-wave plate 58 is arranged with the optical axis at 32.5 degrees, with the P-polarization direction in fig. 4 set to 0 degrees. The half-wave plate 58 is provided with an adjustment mechanism for the rotational direction so that the arrangement angle of the optical axis thereof can be adjusted.

The P-polarized light from the semiconductor laser 51 is converted into 65 degrees in polarization orientation by the half-wave plate 58, and the light intensity of the P-polarized component is 18% and the light intensity of the S-polarized component is 82%.

The half-wave plate 58 is a thin film retardation plate utilizing birefringence due to oblique deposition of a dielectric material. The thin film retardation plate is made of an inorganic material and has excellent durability and reliability as well as inorganic optical crystals such as quartz. Further, since the thin film wavelength plate is formed by laminating films sufficiently thinner than the wavelength of light, the change in the incident angle of the retardation with respect to light is very small as compared with a retardation plate of an inorganic optical crystal such as quartz crystal. Therefore, even when the polarization conversion element is disposed at a position where the converged or diverged light enters, the P-polarization direction from the semiconductor laser 51 can be efficiently rotated and converted. Further, since the half-wave plate 58 is disposed at a position where the convergent light is incident, the size of the half-wave plate 58 can be reduced to 1/2 or less, and the cost of the half-wave plate can be significantly reduced, as compared with the case where the half-wave plate is disposed at a position where the parallel light is incident in the related art.

The light transmitted through the half-wave plate 58 is converted into substantially parallel light by the condenser lens 59, enters the 1 st diffuser 60, is diffused, and enters the dichroic mirror 61.

Fig. 5 shows spectral transmittance characteristics of the dichroic mirror 61. The dichroic mirror 61 has the following characteristics: the wavelength having a transmittance of 50% is 465nm for S-polarized light and 442nm for P-polarized light, and transmits and reflects blue light while transmitting at least 96% of color light including green and red components. The S-polarized component of the light incident on the dichroic mirror 61 is reflected, and the P-polarized component is transmitted. Since the optical axis of the half-wave plate 58 is arranged at 32.5 degrees, the polarization orientation of the incident light becomes 65 degrees, and the light intensities of the S-polarization component and the P-polarization component become 82% and 18%, respectively.

The S-polarized light reflected by the dichroic mirror 61 is condensed by the

condenser lenses

62 and 63, and is superimposed as spot light having a diameter of 1.5mm to 2.5mm, in which the light intensity is 13.5% of the peak intensity, and the spot light is incident on the fluorescent plate 67. The 1 st diffusion plate 60 diffuses light so that the diameter of the spot light becomes a desired diameter. The fluorescent plate 67 is a circular substrate that can be controlled to rotate and includes an aluminum substrate 65 on which a reflective film and a fluorescent layer 64 are formed and a motor 66 located at the center. The reflection film of the fluorescent plate 67 is a metal film or a dielectric film that reflects visible light, and is formed on the aluminum substrate. Further, a phosphor layer 64 is formed on the reflective film. The phosphor layer 64 is formed with a Ce-activated YAG yellow phosphor that emits yellow light including green and red components when excited by blue light. A typical chemical structure of the crystal matrix of the phosphor is Y ₃ Al ₅ O ₁₂ . The phosphor layer 64 is formed in an annular shape.

The phosphor layer 64 excited by the spot light emits yellow light containing green and red components of light. The fluorescent plate 67 is an aluminum substrate, and by rotating it, temperature increase of the fluorescent layer 64 due to the excitation light can be suppressed, and the fluorescence conversion efficiency can be stably maintained. The light incident on the phosphor layer 64 fluoresces the color light of the green and red components and is emitted from the phosphor plate 67. The light emitted toward the reflective film is reflected by the reflective film and is emitted from the fluorescent plate 67. The green light and the red light emitted from the fluorescent plate 67 become natural light, are condensed by the

condenser lenses

62 and 63 again, are converted into substantially parallel light, and then pass through the dichroic mirror 61.

On the other hand, the 18% P-polarized blue light transmitted by the dichroic mirror 61 enters the condenser lens 68 as the 2 nd condenser element and is condensed. The focal length of the condenser lens 68 is set to a condensing angle of 40 degrees or less, and a condensing point is formed near the reflection plate 71. The condensed light condensed by the condenser lens 68 is incident on the 2 nd diffuser 69. The 2 nd diffusion plate 69 diffuses incident light to make the light intensity distribution uniform and to eliminate the speckle of the laser light. The 2 nd diffuser 69 has a diffusing surface formed of fine irregularities on the glass surface of the thin plate. The 2 nd diffusion plate 69 is a diffusion plate in which 1 st transmitted light on the diffusion surface has a diffusion angle of approximately 4 degrees and polarization characteristics are maintained.

The light transmitted through the 2 nd diffusion plate 69 is incident on the quarter-wave plate 70 as the 2 nd phase difference plate. The quarter-wave plate 70 is a retardation plate whose phase difference is 1/4 in the vicinity of the emission center wavelength of the semiconductor laser 51. In fig. 4, the quarter-wave plate 70 is arranged with the optical axis at 45 degrees, with the P-polarization direction set at 0 degrees. The quarter-wave plate 70 is a thin film retardation plate utilizing birefringence due to oblique deposition of a dielectric material. The thin film retardation plate is made of an inorganic material and has excellent durability and reliability as well as inorganic optical crystals such as quartz.

The light transmitted through the quarter-wave plate 70 and converted into circularly polarized light is phase-inverted by the reflection plate 71 formed with a reflection film such as aluminum or a dielectric multilayer film, and the circularly polarized light in the reverse direction becomes divergent light, and is transmitted through the quarter-wave plate 70 and converted into S-polarized light. Further, since no member disturbing polarization is disposed between the quarter-wave plate 70 and the reflection plate 71, P-polarized light can be efficiently converted into S-polarized light.

The S-polarized light converted by the quarter wave plate 70 is diffused again by the 2 nd diffusion plate 69, converted into parallel light by the condenser lens 68, and reflected by the dichroic mirror 61.

Thus, the fluorescent light from the fluorescent plate 67 and the efficiently polarized blue light are combined by the dichroic mirror 61 and emitted as white light. The yellow light including green and red components emitted by fluorescence and the blue light of the semiconductor laser 51 can provide excellent white-balanced emission characteristics. Even if the light emission spectrum characteristics are separated into 3 primary colors of blue, green, and red by an optical system of the projection display device, monochromatic light with desired chromaticity coordinates can be obtained.

In embodiment 1 of the present invention, the separation ratio of blue light is determined by the transmittance characteristic of the dichroic mirror 29 in the blue wavelength band, and the separation ratio is slightly different. On the other hand, in embodiment 2 of the present invention, the separation ratio of the blue light transmitted and reflected by the dichroic mirror 61 is controlled by using the half-wave plate 58 capable of adjusting the arrangement angle of the optical axis, and thus the variation in the separation ratio is very small. Therefore, the deviation of the white balance characteristic becomes very small.

The thin-film retardation plate is used for the half-wave plate 58, but a micro-structural retardation plate using birefringence due to a micro-periodic structure equal to or smaller than the wavelength of light may be used.

In embodiment 2, the half-wave plate 58 is used as the 1 st retardation plate, but a quarter-wave plate may be used as the 1 st retardation plate, and the polarization emitted from the semiconductor laser 51 is arranged to be S-polarized light, and the arrangement angle of the optical axis is adjusted so that the S-polarized component and the P-polarized component of the blue light after transmission become a predetermined ratio.

In embodiment 2, as shown in fig. 4, the configuration in which the half-wave plate 58 is disposed at the position where the divergent light enters is described, but the half-wave plate 58 may be disposed at the position where the convergent light enters. For example, the half-wave plate 58 may be disposed in front of the converging light reflected by the mirror 57.

As described above, the light source device of the present invention polarizes and separates light from a plurality of semiconductor lasers at a fixed ratio by the small half-wave plate and the dichroic mirror arranged at a position where convergent light or divergent light enters, and efficiently condenses and synthesizes yellow light including green and red light, which is excited and emitted by one of the polarized and separated lights, and blue light of the other one of the polarized and separated lights, to obtain white light, and thus can constitute a small, efficient, and inexpensive light source device with a small white balance deviation.

(embodiment mode 3)

Fig. 6 is a diagram showing a configuration of a projection display apparatus 1 according to embodiment 3 of the present invention. As the image forming element, a transmissive liquid crystal panel of an active matrix type is used which is a TN mode or a VA mode and in which a thin film transistor is formed in a pixel region.

The light source device 40 includes: a blue semiconductor laser 21, a heat radiation plate 22, a condenser lens 23, a heat radiation fin 24,

lenses

26, 27, a 1 st diffusion plate 28, a dichroic mirror 29,

condenser lenses

30, 31, a fluorescent plate 35 composed of an aluminum substrate 33 on which a reflective film and a fluorescent layer 32 are formed and a motor 34, a condenser lens 36, a 2 nd diffusion plate 37, a quarter wave plate 38, and a reflection plate 39. Since the light source device 40 according to embodiment 1 of the present invention is described above, a repetitive description thereof will be omitted.

The projection display apparatus 80 according to embodiment 3 further includes: a 1 st lens array plate 200, a 2 nd 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, mirrors 206, 207, 208,

relay lenses

209, 210,

field lenses

211, 212, 213, incident-side

polarizing plates

214, 215, 216,

liquid crystal panels

217, 218, 219, exit-side

polarizing plates

220, 221, 222, a color combining prism 223 composed of a red-reflecting dichroic mirror and a blue-reflecting dichroic mirror, and a projection lens 224.

White light from the light source device 40 enters the 1 st lens array plate 200 composed of a plurality of lens elements. The light beam incident on the 1 st lens array panel 200 is divided into a plurality of light beams. Many of the split light fluxes converge on the 2 nd lens array plate 201 composed of a plurality of lenses. The lens elements of the 1 st lens array sheet 200 are in the shape of openings of similar shape to the

liquid crystal panels

217, 218, 219. The lens elements of the 2 nd lens array sheet 201 determine the focal distances thereof so that the 1 st lens array sheet 200 and the

liquid crystal panels

217, 218, 219 are in a substantially conjugate relationship.

The light emitted from the 2 nd 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, and converts natural light from a light source into light of one polarization direction. Since fluorescent light is natural light, it is polarized and converted into one polarization direction, and blue light enters as S-polarized light and exits as S-polarized light without being polarized and converted.

The light from the polarization conversion element 202 enters the superimposing lens 203. The superimposing lens 203 is a lens for superimposing light emitted from each lens element of the 2 nd lens array sheet 201 on the

liquid crystal panels

217, 218, and 219. The 1 st lens array plate 200 and the 2 nd lens array plate 201, the polarization conversion element 202, and the superimposing lens 203 are used as an illumination optical system.

The light from the superimposing lens 203 is separated into blue light, green light, and red light by a blue reflection dichroic mirror 204 and a green reflection dichroic mirror 205 as color separation elements. The green light is transmitted through the field lens 211 and the incident-side polarizing plate 214, and enters the liquid crystal panel 217. The blue light is reflected by the mirror 206, passes through the field lens 212 and the incident-side polarizing plate 215, and enters the liquid crystal panel 218. The red light is transmitted, refracted, and reflected by the

relay lenses

209 and 210 and the

mirrors

207 and 208, and is transmitted through the field lens 213 and the incident-side polarizing plate 216 to enter the liquid crystal panel 219.

The 3

liquid crystal panels

217, 218, and 219 change the polarization state of incident light by controlling the voltage applied to the pixels in accordance with the video signal, and modulate light by a combination of incident-side

polarizing plates

214, 215, and 216 and exit-side

polarizing plates

220, 221, and 222 arranged on both sides of the

liquid crystal panels

217, 218, and 219, respectively, with transmission axes orthogonal to each other, thereby forming green, blue, and red images. The light beams of the respective colors transmitted through the emission-side

polarizing plates

220, 221, and 222 pass through the color synthesizing prism 223, and the light beams of the respective colors of red and blue are reflected by the red-reflecting dichroic mirror and the blue-reflecting dichroic mirror, respectively, synthesized into green light, and enter the projection lens 224. The light incident on the projection lens 224 is transmitted to a screen (not shown) in an enlarged manner.

The light source device is formed of a plurality of solid-state light sources in a compact size, and efficiently emits white light with a good white balance, so that a projection display device having a long life and high luminance can be realized. Further, since 3 liquid crystal panels using polarized light, not a time division system, are used for the image forming element, a bright and high-definition projected image with good color reproduction without color breakup can be obtained. Further, compared to the case of using 3 DMD elements, the projection display device can be made compact because the total reflection prism is not necessary and the prism for color synthesis is a small prism that enters at 45 degrees.

As described above, the 1 st projection display device of the present invention uses a light source device capable of separating P-polarized light from a semiconductor laser at a constant intensity ratio by a solid light source and a dichroic mirror as semiconductor lasers, and combining yellow light including green and red components excited and emitted by one of the separated light beams and blue light obtained by efficiently polarization-converting the other separated light beam by a small quarter wave plate to obtain white light. Therefore, a small and inexpensive projection display device can be constructed. The light source device 40 shown in fig. 1 is used as the light source device, but the light source device 72 shown in fig. 4 may be used. In this case, the white light emitted from the light source device has a very small variation in white balance, and the light source device and the projection display device can be configured at low cost.

A transmissive liquid crystal panel is used as the image forming element, but a reflective liquid crystal panel may be used. By using the reflective liquid crystal panel, a projection display device which is smaller and more precise can be configured.

(embodiment mode 4)

Fig. 7 shows a projection display apparatus 2 according to embodiment 4 of the present invention. The 2 nd projection display device 90 uses 3 DMDs as image forming elements.

lenses

26, 27, a 1 st diffuser plate 28, a dichroic mirror 29,

condenser lenses

30, 31, a fluorescent plate 35 composed of an aluminum substrate 33 on which a reflective film and a fluorescent layer 32 are formed and a motor 34, a condenser lens 36, a 2 nd diffuser plate 37, a quarter wave plate 38, and a reflector plate 39. The above is the light source device 40 according to embodiment 1 of the present invention.

The white light emitted from the light source device 40 enters the condenser lens 100 and is condensed on the rod (rod) 101. The incident light to the rod 101 is reflected multiple times inside the rod, thereby uniformizing the light intensity distribution and emitting the light. The light emitted from the rod 101 is collected by the relay lens 102, reflected by the mirror 103, transmitted through the field lens 104, and incident on the total reflection prism 105. Here, the condenser lens 100, the rod 101, the relay lens 102, the reflecting mirror 103, and the field lens 104 are examples of the illumination optical system.

The total reflection prism 105 is composed of 2 prisms, and a thin air layer 106 is formed on the surfaces close to the prisms. The air layer 106 totally reflects light incident at an angle equal to or greater than the critical angle. The light from the field lens 104 is reflected by the total reflection surface of the total reflection prism 105 and enters the color prism 107.

The color prism 107 is composed of 3 prisms, and a blue reflection dichroic mirror 108 and a red reflection dichroic mirror 109 are formed on the proximity surface of each prism. The blue reflection dichroic mirror 108 and the red reflection dichroic mirror 109 of the color prism 107 are separated into blue light, red light, and green light, and the separated light is incident on the

DMDs

110, 111, and 112, respectively. The

DMDs

110, 111, and 112 deflect the micromirrors in accordance with the video signal, and reflect the light incident on the projection lens 113 and the light traveling outside the projection lens 113 effectively. The light reflected by the

DMDs

110, 111, and 112 passes through the color prism 107 again. In the process of passing through the color prism 107, the separated lights of the respective colors of blue, red, and green are synthesized and incident on the total reflection prism 105.

The light incident on the total reflection prism 105 is incident on the air layer 106 at a critical angle or less, and therefore, the light is transmitted and incident on the projection lens 113. Thus, the image light formed by the

DMDs

110, 111, and 112 is transmitted to a screen (not shown) in an enlarged manner.

The light source device is composed of a plurality of solid-state light sources, and efficiently emits white light with a good white balance, so that a projection display device with a long life and high luminance can be realized. Further, since the DMD is used for the image forming element, a projection display device having higher light resistance and heat resistance can be configured as compared with an image forming element using liquid crystal. Further, since 3 DMDs are used, a bright and high-definition projected image with good color reproduction can be obtained.

As described above, the 2 nd projection display device according to the present invention uses a light source device capable of separating P-polarized light from a semiconductor laser at a constant intensity ratio by a solid light source and a dichroic mirror as semiconductor lasers, and combining yellow light including green and red components excited and emitted by one of the separated light beams and blue light obtained by efficiently polarization-converting the other separated light beam by a small quarter wave plate to obtain white light. Therefore, a small and inexpensive projection display device can be constructed. The light source device 40 shown in fig. 1 is used as the light source device, but the light source device 72 shown in fig. 4 may be used. In this case, the white light emitted from the light source device has a very small variation in white balance, and the light source device and the projection display device can be configured at low cost.

As described above, embodiments 1 to 4 have been described as an example of the technique disclosed in the present application. However, the technique of the present invention is not limited to this, and can be applied to an embodiment in which a change, a replacement, an addition, an omission, or the like is performed.

The present invention is applicable to a light source device of a projection display device using an image forming element.

Claims

1. A light source device is provided with:

a solid-state light source that emits blue light;

a dichroic mirror that separates light from the solid-state light source;

a 1 st light-collecting element that collects one of the lights separated by the dichroic mirror;

a fluorescent plate which emits green light and red light when excited by the light condensed by the 1 st condensing element;

a 2 nd light-condensing element that condenses the other light separated by the dichroic mirror;

a phase difference plate that converts linearly polarized light into circularly polarized light; and

a reflection plate is arranged on the upper surface of the light guide plate,

a focal length of the 2 nd condensing element is set to a condensing angle of 40 degrees or less, a condensing point is formed in the vicinity of the reflection plate, the retardation plate is a thin film retardation plate made of an inorganic material, and the retardation plate is disposed between the 2 nd condensing element and the reflection plate at a position where the condensed light and the divergent light are incident,

the phase difference plate is a quarter wave plate.

2. A light source device is provided with:

a solid-state light source that emits blue light;

a phase difference plate for converting the polarization direction of the light from the solid-state light source and controlling the light of the P-polarization component and the light of the S-polarization component to a certain ratio;

a dichroic mirror for separating the polarization of the light from the phase difference plate;

a 1 st light-collecting element that collects one of the lights separated by the dichroic mirror; and

a fluorescent plate which emits green light and red light by being excited by the light condensed by the 1 st condensing element,

the retardation plate is a thin film retardation plate made of an inorganic material, and is disposed between the solid-state light source and the dichroic mirror at a position where converging light or diverging light is incident,

the phase difference plate is disposed at a position where an incident light angle is 40 degrees or less.

3. The light source device according to claim 2, wherein the phase difference plate is a half-wave plate or a quarter-wave plate.

4. The light source device according to claim 1 or 2, wherein the retardation plate is an inorganic thin film retardation plate using birefringence due to oblique deposition.

5. A light source device is provided with:

a solid-state light source that emits blue light;

a 1 st phase difference plate for converting the polarization direction of the light from the solid-state light source and controlling the light of the P-polarization component and the S-polarization component to a certain ratio;

a dichroic mirror for separating the light from the 1 st phase difference plate into polarized light;

a 2 nd condensing element that condenses the other light separated by the dichroic mirror;

a 2 nd phase difference plate for converting linearly polarized light into circularly polarized light; and

a reflection plate is arranged on the upper surface of the light guide plate,

the 1 st phase difference plate is a thin film phase difference plate made of an inorganic material, and is disposed between the solid-state light source and the dichroic mirror at a position where converging light or diverging light enters,

the 2 nd retardation plate is a thin film retardation plate made of an inorganic material, and is disposed between the 2 nd light collecting element and the reflection plate at a position where converging light and diverging light are incident,

the focal length of the 2 nd condensing element is set to be 40 degrees or less, a condensing point is formed near the reflecting plate,

the 1 st phase difference plate is arranged at a position where an incident light angle is 40 degrees or less,

the 2 nd phase difference plate is a quarter wave plate.

6. The light source device according to claim 5, wherein the 1 st phase difference plate is a half-wave plate or a quarter-wave plate.

7. The light source device according to claim 5, wherein at least one of the 1 st phase difference plate and the 2 nd phase difference plate is an inorganic thin film phase difference plate using birefringence due to oblique deposition.

8. The light source device according to claim 1, 2 or 5, the solid-state light source being a blue semiconductor laser.

9. The light source device according to claim 1, 2 or 5, wherein the light emitted from the solid-state light source is linearly polarized light.

10. A projection display device includes:

a light source;

an illumination optical system that condenses light from the light source and illuminates an illuminated area;

an image forming element that forms an image based on a video signal; and

a projection lens that projects an image formed by the image forming element in an enlarged manner,

the light source is the light source device of claim 1, 2 or 5.

11. The projection-type display apparatus of claim 10, wherein the image forming element is a liquid crystal panel.

12. The projection type display apparatus according to claim 10, wherein the image forming element is a DMD (digital micromirror device) of a mirror deflection type.