JP6290369B2 - Projection-type image display device and light source device - Google Patents

Description

  The present invention relates to a light source device.

  In a projection-type image display apparatus that enlarges and displays a display screen of an image display element on a projection surface, the illumination optical system has been devised so that an enlarged image having a sufficient size and brightness can be obtained on the projection surface. In particular, development of a projection-type image display apparatus using solid-state light emitting elements such as red, green, and blue light emitting diodes and organic EL has been performed.

  For example, there has been proposed a light source device that emits light with high efficiency even when excitation light emitted from a solid light source is visible light (see Patent Document 1).

JP 2011-13313 A

  According to Patent Document 1, there is a problem in that the excitation light is irradiated to the phosphor in a concentrated manner at one point, resulting in a decrease in luminous efficiency and lifetime of the phosphor.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a light source device and a projection display device that improve the luminous efficiency and life of a phosphor.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  In order to solve the above problems, one of the desirable embodiments of the present invention is as follows. The light source device includes an excitation light source that emits excitation light, a phosphor that emits fluorescent light when excited by the excitation light, and an optical member that guides the excitation light to the phosphor, and the curvature of the optical member Is set so that the excitation light transmitted through the optical member enters the phosphor with the tip of the phosphor as the condensing position.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  ADVANTAGE OF THE INVENTION According to this invention, the light source device and projection type video display apparatus which improved the luminous efficiency and lifetime of fluorescent substance can be provided.

1 is a main part configuration diagram of a light source device in Embodiment 1. FIG. FIG. 6 is a main part configuration diagram of a light source device in Embodiment 2. FIG. 2 is a diagram illustrating an optical system of a projection display apparatus using the light source device according to the first embodiment. FIG. 2 is a diagram illustrating an optical system of a projection display apparatus using the light source device according to the first embodiment. It is explanatory drawing of etendue. It is a principal part block diagram of the light source device assumed as a subject.

  Hereinafter, examples will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same part and the description is abbreviate | omitted about what was once demonstrated. In this paper, the light source of the excitation light source group 1 is described as a laser having a small emission area. The laser has a luminance distribution in which the central part is bright and the peripheral part is dark.

  First, the problem of the present invention will be described. FIG. 6 is a main part configuration diagram of a light source device assumed as a problem.

  In FIG. 6A, the excitation light 10 emitted from the excitation light source group 1 becomes substantially parallel light by the collimator lens 2, passes through the convex lens 3 and the concave lens 4, and is incident on the dichroic mirror 5 with a narrowed beam width. . The dichroic mirror 5 has a characteristic of transmitting the wavelength range of the excitation light 10 and reflecting the wavelength range of the fluorescent light 11. Therefore, the excitation light 10 passes through the dichroic mirror 5, passes through the condenser lens 6, and then enters the rotation-controllable disk 9 coated with the phosphor 7.

  The condenser lens 6 is set to have a curvature so that the incident parallel light is condensed on the irradiation region 8 on the disk 9. That is, the light emission luminance distribution of the excitation light source group 1 is enlarged on the phosphor 7 through a plurality of lens groups, and is irradiated on the irradiation region 8. The phosphor 7 excited by the excitation light 10 emits fluorescence light 11. After passing through the condenser lens 6, the fluorescent light 11 becomes substantially parallel light, is reflected by the dichroic mirror 5, and enters the subsequent illumination optical system.

  6B and 6C show the irradiation region 8 of the excitation light 10 on the phosphor 7, FIG. 6B is a two-dimensional excitation light distribution diagram, and FIG. 6C is a cross-sectional view. It is a luminance distribution. The excitation light 10 irradiated onto the phosphor 7 has a bright central portion and a dark peripheral portion, as in the laser luminance distribution. When the phosphor absorbs the excitation light and emits the fluorescence light, it generates heat according to the difference between the wavelength (energy) of the excitation light and the fluorescence light. Therefore, in the irradiation region 8, if the center brightness is high, the center temperature becomes extremely high, leading to a decrease in luminous efficiency and lifetime of the phosphor.

  If the luminance distribution of the excitation light applied to the phosphor is increased in order to lower the temperature of the phosphor, the efficiency in the subsequent illumination optical system is lowered. This is due to the preservation of the lighting etendue (details will be described later).

  In addition, by shifting the disk 9 itself in the incident direction of the excitation light 10, it is possible to prevent the excitation light 10 from being irradiated before being incident on the phosphor 7 at one place and condensing at one place on the phosphor 7. Is also possible. However, in order to capture the fluorescent light 11 emitted from the phosphor 7, the distance between the condenser lens 6 and the phosphor 7 is generally set as close as possible. Therefore, in practice, the phosphor 7 cannot be brought closer to the condenser lens 6.

  In addition, by shifting the disk 9 itself in the direction of emission of the excitation light 10, the light is condensed at one place before entering the phosphor 7, and then the excitation light 10 is irradiated to the phosphor 7 when the irradiation area is widened. It is also conceivable to prevent the light from being condensed at one place on the phosphor 7. However, if the distance between the phosphor 7 and the condenser lens 6 is increased, the fluorescent light 11 emitted from the phosphor 7 cannot be captured by the condenser lens 6.

Example 1
FIG. 1 is a main part configuration diagram of the light source device according to the first embodiment. The main difference between FIG. 1 (A) and FIG. 6 (A) is that the condensing lens 6 has a divergent excitation light 10 by devising the position and the radius of curvature of the convex lens 3, the concave lens 4, or both. At the point of incidence. Then, the excitation light 10 transmitted through the condensing lens 6 has the tip of the phosphor 7 as a condensing position (so that the condensing position is on the emission side of the excitation light 10 with respect to the phosphor 7). 7 is incident. Specifically, the curvature of the convex lens 3 is relaxed, the curvature of the concave lens 4 is tightened so that the excitation light 10 enters the condenser lens 6 in a divergent manner, and the position of the convex lens 3 is moved to the concave lens 4 side by several mm. It is conceivable to make adjustments such as moving the position of the concave lens 4 to the convex lens 3 side by several mm.

  1B and 1C show an irradiation region 8 of the excitation light 10 on the phosphor 7, FIG. 1B is a two-dimensional excitation light distribution diagram, and FIG. It is a luminance distribution. In this case, since the plurality of excitation lights are irradiated to the irradiation region 8 not at one place but at positions where the excitation light is scattered almost evenly, a substantially uniform luminance distribution with a slight defocus is obtained. Therefore, the temperature rise at the center of the irradiation region 8 can be prevented, and the luminous efficiency and lifetime of the phosphor can be improved.

  In addition, although demonstrated as what devised the position and curvature radius of the convex lens 3, the concave lens 4, or both of them, the excitation light 10 which permeate | transmitted the condensing lens 6 made the tip of the fluorescent substance 7 the condensing position, and the fluorescent substance 7 Or an optical member of a lens system disposed between the excitation light source group 1 and the phosphor 7 so as to be incident on the light source, that is, any one of the convex lens 3, the concave lens 4, and the condenser lens 6, or You may devise the position and curvature radius of the lens of those combinations. For example, the curvature of the condenser lens 6 may be relaxed. However, in this case, since the fluorescent light 11 does not become parallel by the condenser lens 6 but becomes divergent, one lens for making the fluorescent light 11 parallel after being reflected by the dichroic mirror 5 is required.

(Example 2)
FIG. 2 is a main part configuration diagram of the light source device according to the second embodiment. The main difference between FIG. 2 (A) and FIG. 1 (A) is that the excitation light 10 emitted from the excitation light source group 1 is made incident on the optical fiber group 13 by the condenser lens 12. The optical fiber group 13 has an emission surface bundled at one place. The light emission luminance distribution on the exit surface of the optical fiber group 13 is enlarged on the phosphor 7 through a plurality of lens groups and is irradiated onto the irradiation region 8. Since the light emission luminance distribution on the exit surface of the optical fiber group 13 is substantially uniform, the luminance distribution in the irradiation region 8 is also substantially uniform. That is, there is no need to defocus with a lens as in the first embodiment.

  If the luminance distribution of the irradiation region 8 can be made substantially uniform, the exit surfaces of at least two or more optical fibers in the optical fiber group 13 need only be bundled at one or more locations.

  2B and 2C show the irradiation region 8 of the excitation light 10 on the phosphor 7, FIG. 2B is a two-dimensional excitation light distribution diagram, and FIG. It is a luminance distribution. Also in this case, similarly to FIG. 1, the temperature rise at the center of the irradiation region 8 can be prevented, and the luminous efficiency and lifetime of the phosphor can be improved.

(Example 3)
Next, the optical system of the projection display apparatus will be described. FIG. 3 is a diagram illustrating a configuration of a projection display apparatus using the light source device according to the first embodiment.

  FIG. 3A is a schematic configuration diagram of an optical system of a projection display apparatus including the light source device of FIG. Here, it is assumed that the excitation light source group 1 emits blue excitation light 10 and the phosphor 7 is a green phosphor. At this time, the dichroic mirror 5 has a characteristic of transmitting blue light and reflecting green light. The green light becomes substantially parallel light after passing through the condenser lens 6, is reflected by the dichroic mirror 5, passes through the condenser lens 15, and enters the dichroic mirror 16.

  The dichroic mirror 16 has a characteristic of transmitting green light and reflecting red light and blue light. Accordingly, the green light passes through the dichroic mirror 16 and enters the multiple reflection element 23. The condensing lens 15 is set to have a curvature so as to collect light at the incident aperture of the multiple reflection element 23, and the incident aperture surface of the multiple reflection element 23 is similar to the irradiation shape of the irradiation region 8 of the blue excitation light. The shape is formed.

  The light source 17 is an LED red light source. The red light emitted from the light source 17 becomes parallel by the collimating lens 18 and enters the dichroic mirror 21. The dichroic mirror 21 has a characteristic of transmitting red light and reflecting blue light. Accordingly, the red light passes through the dichroic mirror 21, passes through the condenser lens 22, and enters the dichroic mirror 16.

  On the other hand, the light source 19 is an LED blue light source. The blue light emitted from the light source 19 is collimated by the collimating lens 20 and enters the dichroic mirror 21. The blue light is reflected by the dichroic mirror 21, passes through the condenser lens 22, and enters the dichroic mirror 16.

  The dichroic mirror 16 has a characteristic of transmitting green light and reflecting red light and blue light. Accordingly, the red light and the blue light incident on the dichroic mirror 16 are reflected by the dichroic mirror 16 and enter the multiple reflection element 23.

  The condensing lens 22 is set to have a curvature so as to collect light at the entrance aperture of the multiple reflection element 23. The entrance aperture surface of the multiple reflection element 23 has a shape similar to the light emission shapes of the light source 17 and the light source 19. Is formed. The arrangement position of the light source 17 and the light source 19 may be changed by changing the characteristics of the dichroic mirror 21.

  The red light, green light, and blue light incident on the multiple reflection element 23 are reflected by the multiple reflection element 23 a plurality of times, and become light having a uniform illuminance distribution on the exit aperture surface of the multiple reflection element 23. The shape of the exit aperture surface of the multiple reflection element 23 is substantially similar to that of the image display element 26. The condenser lens 24 is set to a curvature that enlarges and forms an image formed on the exit aperture surface of the multiple reflection element 23 on the image display element 26. Therefore, red light, green light, and blue light emitted from the exit aperture surface of the multiple reflection element 23 are transmitted through the condenser lens 24, reflected by the reflection mirror 25, and then irradiated onto the image display element 26 with a uniform illuminance distribution. Is done.

  The excitation light source group 1, the light source 17, and the light source 19 are solid-state light emitting elements with a fast response speed and can be time-division controlled. Accordingly, each color light is modulated by the video display element 26 in a time division manner for each color light. Each color light reflected by the image display element 26 enters the projection lens 27 and is projected on a screen (not shown).

  FIG. 3B shows the irradiation area 8 on the phosphor 7, the entrance / exit aperture shape of the multiple reflection element 23, and the effective area of the image display element 26. Since the exit aperture shape of the multiple reflection element 23 is enlarged and projected onto the image display element 26, the exit aperture shape of the multiple reflection element 23 is substantially similar to the effective area of the image display element 26. Since the entrance aperture shape of the multiple reflection element 23 is generally the same as the exit aperture shape, the entrance aperture shape of the multiple reflection element 23 is substantially similar to the effective area of the image display element 26. Further, as described above, the light emission luminance distribution of the light source is enlarged and irradiated on the incident aperture shape of the multiple reflection element 23. Therefore, if the light emission luminance distribution of the light source is similar to the shape of the incident aperture of the multiple reflection element 23, the efficiency is the highest. That is, it is most efficient that the light emission luminance distribution of the light source is substantially similar to the effective area of the video display element 26.

  FIG. 4 is a diagram showing a configuration of a projection display apparatus using the light source device according to the first embodiment, which is different from FIG.

  The main differences between FIG. 3A and FIG. 4A are the characteristics of the dichroic mirror 5 and the arrangement of the condenser lens 6 and the disk 9. Here, the dichroic mirror 5 has a characteristic of reflecting blue light and transmitting green light. The blue light is reflected by the dichroic mirror 5 and changed to green light by the phosphor 7, and then passes through the dichroic mirror 5 and enters the condenser lens 15. The subsequent steps are the same as those in FIG. In FIG. 4B, the luminance distribution is the same as that in FIG. 3 and 4, the light source device according to the first embodiment has been described. However, the light source device according to the second embodiment may be used.

  Next, the optimal light emission area of the light source will be described. FIG. 5 is an explanatory diagram of etendue. The fluorescent light emitted from the irradiation region 8 is enlarged and irradiated onto the image display element 26 by the optical member 28. The optical member 28 is generally composed of a plurality of optical members, but here, a single lens is used instead.

  The light emitted from the image display element 26 is enlarged and projected from the projection lens 27 onto the screen. The brightness that can be projected from the projection lens is determined by the product (illumination etendue) of the solid angle determined by the area of the image display element and the F value that is the brightness parameter of the projection lens. Since the illumination etendue is conserved, the product of the light emission area and the light solid angle determined on the light source side (light source etendue) cannot be more than the illumination etendue. Therefore, when the light emitting area of the light source is increased, the light divergence angle that can be captured by the illumination optical system is decreased, and the illumination efficiency is decreased.

  The area of the image display element 26 is A, the area of the excitation light irradiation region 8 is B, the light capture half angle determined by the F value of the projection lens 27 is θa, and the light beam divergence angle of the fluorescent light emitted from the irradiation region 8 is θb. Then, the solid angle determined by the F value of the projection lens 27 is 2π (1-cos θa), and the solid angle of the fluorescent light emitted from the irradiation region 8 of the excitation light is 2π (1-cos θb). Substantially established.

A × 2π (1-cosθa) ≈B × 2π (1-cosθb) (Equation 1)
Fluorescent light that diverges from the irradiation region 8 diverges in all directions, but is reflected by the substrate of the disk 9, so that the solid angle of the fluorescent light is 2π. Therefore, (Equation 1) can be replaced with (Equation 2).

A x 2π (1-cosθa) ≒ B x 2π (Equation 2)
The F value of the projection lens 27 and the light beam divergence angle θa are expressed by the following equation (3).
tanθa = 1 / (2 × F) (Equation 3)
From (Expression 2) and (Expression 3), (Expression 4) is substantially established.

B ≒ A × (1-cos (arctan (1 / (2 × F))) (Equation 4)
Since the F value of the projection lens of the projection display apparatus is generally 1.5 to 3.0, if the range of (Equation 5) is selected as the area B of the excitation light irradiation region 8 from (Equation 4). Good.
0.0136 × A ≦ B ≦ 0.0513 × A (Expression 5)
Further, since the luminance distribution in the irradiation region 8 has a certain spread, it is difficult to clearly define the region. Therefore, the irradiation region 8 is defined as a region up to 1 / e2 (≈13.5%) of the luminance peak.

  In the above embodiment, the green light is described as the fluorescent light excited by the excitation light source, the blue light, and the red light as the LED light, but other variations are also conceivable. For example, red light is LED and green light and blue light are fluorescent light, blue light is LED and green light and red light are fluorescent light, or red light, green light and blue light are all fluorescent light, etc. is there.

  Moreover, the example which rotates the fluorescent substance 7 was shown. This is because organic silicon resin or the like is used as a binder that disperses and hardens the phosphor, so that it is necessary to prevent burning due to temperature. However, it is not necessary to rotate the phosphor as long as the lifetime of the phosphor can be ensured by using an inorganic binder.

  Moreover, although it demonstrated that there existed multiple excitation light sources and optical fibers, one may be sufficient. Further, although the video display element has been described as a DMD (Digital Micromirror Device) element, it may be a liquid crystal type video display element.

DESCRIPTION OF SYMBOLS 1 ... Excitation light source group, 2 ... Collimating lens group, 3 ... Convex lens, 4 ... Concave lens, 5 ... Dichroic mirror, 6 ... Condensing lens, 7 ... Phosphor, 8 ... Excitation light irradiation area | region, 9 ... Disc, 10 ... Excitation Light, 11 ... fluorescent light, 12 ... condensing lens group, 13 ... optical fiber group

Claims (8)

A light source device;
An image display element;
An illumination optical system having a plurality of optical elements that irradiate the image display element with light from the light source device;
A projection lens that magnifies and projects an optical image formed by the video display element,
The light source device
An excitation light source that emits excitation light;
A phosphor that emits fluorescent light when excited by excitation light;
A dichroic mirror disposed between the excitation light source and the phosphor;
An optical member disposed between the excitation light source and the dichroic mirror;
A first condenser lens disposed between the phosphor and the dichroic mirror,
The first condenser lens is set so that excitation light is incident on the phosphor with the tip of the phosphor as a condensing position,
Excitation light is reflected by the dichroic mirror and incident on the phosphor.
Fluorescent light passes through the dichroic mirror and enters the illumination optical system ,
The optical member includes a convex lens and a concave lens,
The convex lens and the concave lens are arranged in this order from the excitation light source toward the dichroic mirror,
A projection display apparatus comprising an adjustment mechanism for adjusting a positional relationship between the convex lens and the concave lens . The projection display apparatus according to claim 1, wherein
The optical member is
A second condenser lens for condensing the excitation light from the excitation light source;
And a group of optical fibers into which the excitation light condensed by the second condenser lens is incident. The projection display apparatus according to claim 2, wherein
A projection-type image display apparatus in which at least two or more optical fibers of the optical fiber group are bundled at one or more places. The projection display apparatus according to claim 1 , wherein
A projection display apparatus, wherein the curvature of at least one of the convex lens and the concave lens is set so that excitation light is incident on the phosphor with the tip of the phosphor as a condensing position. In the projection display apparatus according to any one of claims 1 to 4 ,
A projection-type image display apparatus, wherein a luminance distribution of excitation light applied to the phosphor is substantially similar to that of the image display element. In the projection type video display device according to any one of claims 1 to 5 ,
Projection-type image display satisfying 0.0136 × A ≦ B ≦ 0.0513 × A, where B is the luminance distribution area of the excitation light irradiated on the phosphor and A is the area of the image display element. apparatus. In the projection type video display device according to any one of claims 1 to 6 ,
The illumination optical system includes a multiple reflection element,
The projection display apparatus, wherein the shape of the light incident surface of the multiple reflection element is substantially similar to the shape of the excitation light irradiation region of the phosphor. An excitation light source that emits excitation light;
A phosphor that emits fluorescent light when excited by excitation light;
A dichroic mirror disposed between the excitation light source and the phosphor;
An optical member disposed between the excitation light source and the dichroic mirror;
A condenser lens disposed between the phosphor and the dichroic mirror,
The condensing lens is set so that excitation light enters the phosphor with the tip of the phosphor as a condensing position,
Excitation light is reflected by the dichroic mirror and incident on the phosphor, and the fluorescent light passes through the dichroic mirror ,
The optical member includes a convex lens and a concave lens,
The convex lens and the concave lens are arranged in this order from the excitation light source toward the dichroic mirror,
A light source device comprising an adjustment mechanism for adjusting a positional relationship between the convex lens and the concave lens .