JP2004070018A - Illumination optical system structure of projection device and projection device - Google Patents

Abstract

[PROBLEMS] To irradiate light from red, green, and blue light sources on the same optical axis using a dichroic prism, and to project an image obtained by irradiating a light valve onto a screen in an enlarged manner. It was difficult to supply a sufficient projection luminous flux.
A blue-green light-emitting diode (11BG) is further added to red, green, and blue light-emitting diodes (11R, 11G, and 11B) as light sources, and light paths of the light sources of three or more colors can be aligned on the same optical axis. The wavelength combining prisms 23 and 32 having excellent reflection / transmission efficiency by utilizing total reflection are provided.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a configuration of a projection device that projects an image on a screen, and particularly to a configuration of an illumination optical system that illuminates a light valve.
[0002]
[Prior art]
FIG. 7 is a schematic configuration diagram of the illumination device 100 for explaining the disclosure content described in JP-A-10-269802.
[0003]
In the figure, 101R is a light emitting diode for emitting a red light beam, 102R is a kaleidoscope for uniforming the illuminance distribution of the red light beam emitted from the light emitting diode 101R, 103R is a relay lens, 104R is a field lens, and 105R is a light. It is a valve. Similarly, 101G and 101B are light emitting diodes for emitting green and blue light beams, respectively. 102G and 102B are kaleidoscopes for uniforming the illuminance distribution of green and blue light beams emitted from the light emitting diodes 101G and 101B, respectively. 103B is a relay lens, 104G and 104B are field lenses, and 105G and 105B are light valves. Reference numeral 106 denotes a dichroic prism for synthesizing light beams of three colors, 107 denotes a projection lens, and 108 denotes a screen.
[0004]
In addition, the suffixes R, G, and B of the capital letters in the drawing indicate that the elements are related to the red, green, and blue light beams, respectively. Hereinafter, in the same manner, upper case suffixes R, G, and B are used for the signs.
[0005]
Next, the operation of the above conventional example will be described. The red, green, and blue luminous fluxes emitted from the light emitting diodes 101R, 101G, and 101B enter the kaleidoscopes 102R, 102G, and 102B, respectively, and are repeatedly subjected to total internal reflection. It becomes uniform light. Then, the light valves 105R, 105G, and 105B are respectively illuminated via the relay lenses 103R, 103G, and 103B and the field lenses 104R, 104G, and 104B.
[0006]
These illumination lights are spatially modulated by the light valves 105R, 105G, and 105B, respectively, and output on the same optical axis by the dichroic prism 106 to be imaged. After that, the image is enlarged and projected on the screen 108 by the projection lens 107.
[0007]
8A and 8B are diagrams for explaining the operation of a typical dichroic prism 106. FIG. 8A is an external perspective view showing the optical path relationship between the dichroic prism 106 and its input / output light, and FIG. Is a spectral characteristic graph showing the spectral characteristics of the dichroic prism 106. The horizontal axis of this spectral characteristic graph indicates the wavelength of the incident light, and the vertical axis indicates the transmittance, which is the ratio between the incident light and the transmitted light. FIG. 8 refers to page 185 of the design of a projection television by Trikeps, ISBN4-88657-107-4.
[0008]
In the conventional example shown in FIG. 7 using the dichroic prism 106, illumination light from a light emitting diode that emits an equal amount of an S-polarized component and a P-polarized component due to natural light cannot be used effectively. For example, the P-polarized light component of the 530 nm green light beam emitted by the light emitting diode 101G can transmit 90% or more of the dichroic prism 106, but the S-polarized light component can transmit only 30 to 40%, and the remaining 60% of the S-polarized light component. To 70% of the light will be unavailable.
[0009]
Further, looking at the spectral characteristics of blue light in S-polarized light, the reflectance changes from approximately 10% to 90% when the wavelength changes from 580 nm to 520 nm and changes by about 60 nm. The fact that the separation characteristic with respect to the wavelength is not steep as described above means that it is difficult to increase the luminous flux of the illumination device by combining light having a center wavelength of 500 nm between the center wavelengths of 470 nm and 530 nm on the same optical axis. Means
[0010]
On the other hand, FIG. 9 is a configuration diagram showing a configuration of a projection device 200 as a reference example (thus not a conventional example) for clarifying the effects of the present invention described later. This projection apparatus 200 uses an integrator using a lens array instead of the kaleidoscopes 102R, 102G, and 102B used for uniformizing the illuminance distribution in the conventional example of FIG. One digital micromirror element is used. In this case, it was estimated how much the light flux from the light source is projected on the screen.
[0011]
In FIG. 9, reference numerals 19R, 19G, and 19B denote collimator lenses that collimate red, green, and blue emitted light beams emitted from light-emitting diodes 11R, 11G, and 11B as light sources, respectively, and a first lens array 50. 51 is a second lens array, 56 is an integrator composed of a first lens array 50 and a second lens array 51, 52 is a superimposed lens, 53 is a condenser lens, 54 is a total reflection prism, and 55 is a digital micromirror array. It is a light valve. The projection lens 57 and the screen 58 are the same as the projection lens 107 and the screen 108 shown in FIG.
[0012]
In the case of this projection device 200, since the number of the light valves 55 is one, the light emitting diodes 11R, 11G, and 11B are sequentially turned on, and while one light emitting diode is turned on, the other two are turned off. Will be driven. That is, a red image, a green image, and a blue image are repeatedly projected onto the screen at a speed of several tens of times or more per second, and are additively mixed by human eyes.
[0013]
FIG. 10 summarizes the factors that reduce the luminous flux in the optical path from the light emitting diode, which is the light source, to the screen, the efficiency of each factor, and the luminous flux utilization efficiency up to the final screen in the projection device 200 having the above configuration. It is a graph.
[0014]
The operation of the projection device 200 will be described with reference to the light flux utilization efficiency with reference to the graph of FIG.
[0015]
The red, green, and blue emitted lights respectively emitted from the light emitting diodes 11R, 11G, and 11B are made substantially parallel by the respective collimator lenses 19R, 19G, and 19B. The numerical aperture of each of the collimator lenses 19R, 19G, and 19B is set to sin60 degrees = 0.866, and the light distribution of the light emitted from the light emitting diode is proportional to the cosine from the perpendicular to the light emitting surface of the light emitting diode. Assuming that 75% of the luminous flux emitted from the light emitting diode can be extracted forward by the collimator lens.
[0016]
The three colors of illumination light, which have been made substantially parallel by the respective collimator lenses 19R, 19G, and 19B, enter the dichroic prism 106 and are aligned on the same optical axis by transmission / reflection. From the spectral characteristics of the dichroic prism 106, the P-polarized light reflectance at red (center wavelength 630 nm) is estimated to be 50% and the S-polarized light reflectance is 98%, so that the average reflectance can be assumed to be 74%.
[0017]
Similarly, since the transmittance of P-polarized light in green (center wavelength: 530 nm) is estimated to be 98% and the transmittance of S-polarized light is estimated to be 50%, the average transmittance can be assumed to be 74%. Further, since the P-polarized light reflectance in blue (center wavelength 470 nm) is estimated to be 50% and the S-polarized light reflectance is estimated to be 98%, the average reflectance can be assumed to be 74%.
[0018]
Next, it is assumed that the light use efficiency in each optical path from each collimator lens 19R, 19G, 19B to the projection lens 57 is 67 ± 20%. This is a numerical value determined by the light emitting area and light distribution of each of the light emitting diodes 11R, 11G, and 11B, the area of the digital micromirror array serving as the light valve 55, the numerical aperture of the projection lens 57, and the like. When the light emitting areas of 11G and 11B are small and the area of the digital micromirror array constituting the light valve 55 is large, the value approaches 100%.
[0019]
Further, the effective reflectivity of the digital micromirror array is set to 64%, the loss caused by the irradiation margin by irradiating the digital micromirror array larger than the effective area is 16%, and the transmittance of the total reflection prism 54 is 90%. Loss on the glass-air interface 12 from the entrance surface of the collimator lenses 19R, 19G and 19B to the output surface of the condenser lens 53 and the loss on the glass-air interface 20 of the projection lens (assuming 10 lenses) (0 per surface). Assuming that the transmittance in consideration of 0.5%) is 85.1%, the effective utilization rate of the above three factors is 64.3% (0.84 × 0.9 × 0.851 × 100). be able to.
[0020]
Therefore, as shown in FIG. 10, the ratio of the luminous flux reaching the screen 58 out of the luminous flux emitted by each of the light emitting diodes 11R, 11G, 11B is as follows.
0.75 × 0.74 × (0.67 ± 0.20) × 0.64 × 0.643
= 0.153 ± 0.046
That is, it is about 15.3 ± 4.6%, which is a considerably small value.
[0021]
[Problems to be solved by the invention]
As described above, the illumination optical system in the conventional projection apparatus 100 shown in FIG. 7 has a simple structure, but since dichroic prisms are used to combine the illumination light of each color on the same optical axis, three or more colors are used. However, there is a problem that it is difficult to efficiently synthesize the light. This is because the spectral characteristics of the dichroic prism largely depend on the polarization direction of the incident light, greatly depend on the incident angle, and the wavelength separation characteristics are poor.
[0022]
Further, as is apparent from the description of the projection device 200 according to the reference example shown in FIG. 9, the projection device using the dichroic prism has a problem that the light flux utilization efficiency of the light source is reduced.
[0023]
SUMMARY OF THE INVENTION An object of the present invention is to solve these problems, increase the efficiency of use of light flux of a light source, and also make it possible to align illumination light of three or more colors on the same optical axis, thereby increasing the illumination light flux to a light valve. An object of the present invention is to provide an illumination optical system structure and a projection device of the device.
[0024]
[Means for Solving the Problems]
The illumination optical system structure of the projection device according to claim 1, wherein a light beam output from a light source is emitted to a light valve, and an image formed by the light valve is projected on a screen by a projection lens. And
A first light source that emits light with red, green, and blue as central wavelengths; a second light source that emits a color with a central wavelength different from the central wavelength of the color of the first light source; Wavelength synthesizing means for inputting light fluxes respectively output from the light source and the second light source and outputting the light fluxes on substantially the same optical axis;
It is characterized by having.
[0025]
The illumination optical system structure of the projection device according to claim 2, wherein a light beam output from a light source is emitted to a light valve, and an image formed by the light valve is projected on a screen by a projection lens. And
Each light source that emits light with red, green, and blue as central wavelengths, and a light flux input from at least one of the light sources is once totally reflected, then reflected by a dielectric multilayer film, and input from another light source to form the dielectric material. A wavelength combining prism configured to output light beams having different wavelengths transmitted through the multilayer film and substantially on the same optical axis;
It is characterized by having.
[0026]
The illumination optical system structure of the projection device according to claim 3, wherein a light beam output from a light source is emitted to a light valve, and an image formed by the light valve is projected on a screen by a projection lens. And
Red, green, blue green, each light source that emits light with blue as the central wavelength, and the light flux input from at least one of the light sources is once totally reflected, reflected by the dielectric multilayer film, and input from another light source. A wavelength combining prism configured to output light beams having different wavelengths transmitted through the dielectric multilayer film and substantially on the same optical axis;
It is characterized by having.
[0027]
The illumination optical system structure of the projection device according to claim 4 is the illumination optical system structure of the projection device according to claim 3,
The center value of the emission wavelength of the light source is 470 ± 20 nm for blue, 530 ± 20 nm for green, and 500 ± 20 nm for turquoise.
The illumination optical system structure of the projection device according to claim 5 is the illumination optical system structure of the projection device according to any one of claims 1 to 4.
The light source is constituted by a light emitting diode and / or a semiconductor laser.
The illumination optical system structure of the projection device according to claim 6 is the illumination optical system structure of the projection device according to claim 5,
The light source of each color is driven to emit light sequentially.
[0028]
The projection device of claim 7 is
An illumination optical system structure of the projection device according to claim 1, a light valve that forms a projection image by irradiating a light beam output on the same optical axis, and the projection image on a screen. With a projection lens to project
It is characterized by having.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a main configuration diagram showing a main configuration of a projection device 1 according to a first embodiment having an illumination optical system structure according to the present invention.
[0030]
The main differences between this projection apparatus 1 and the projection apparatus 200 shown as a reference example in FIG. 9 are that a light emitting diode 11SG for generating a second green light is added, and that the wavelength synthesis is performed in place of the dichroic prism 106. That is, the container 2 is provided. Therefore, the same parts as those of the projection device 200 shown as the reference example in FIG. 9 of the projection device 1 of the first embodiment are denoted by the same reference numerals, and different points will be mainly described.
[0031]
In FIG. 1, each of 11R, 11G, and 11B is a light emitting diode as a first light source that emits red, green, and blue light, and 11SG is a second green light having a light emission center wavelength different from that of the light emitting diode 11G. A light-emitting diode as a second light source that emits light of the same type. Reference numerals 19R, 19G, 19B, and 19SG denote collimator lenses, and 26 denotes a wavelength synthesizer as wavelength synthesis means. Reference numerals 50 to 58 denote a first lens array, a second lens array, a superimposing lens, a condenser lens, a total reflection prism, a light valve, an integrator, a projection lens, and a screen, respectively. The same as the device 200 is adopted.
[0032]
In the projection device 1 having the above configuration, the optical system excluding the total reflection prism 54, the light valve 55, the projection lens 54, and the screen 55 corresponds to an illumination optical system.
[0033]
Next, the operation of the projection device 1 according to the first embodiment having the above configuration will be described. The light emitted from each of the light emitting diodes 11R, 11G, 11B, and 11SG is substantially collimated by the collimator lenses 19R, 19G, 19B, and 19SG, and is incident on the wavelength combiner 2. The wavelength combiner 2 outputs the incident light beams while aligning them substantially on the same optical axis.
[0034]
Here, the wavelength synthesizer 2 is composed of an element using the spectral reflection characteristics of a dielectric multilayer film such as a dichroic mirror and a dichroic prism, or a combination of wavelength synthesizing elements such as an interference filter. In the case of the second green light emitting diode 11SG, it is possible to combine them on the same optical axis by utilizing the fact that the center wavelength of light emission is different.
[0035]
As described above, the light beams of the three colors aligned on the same optical axis enter the integrator 56 constituted by the first lens array 50 and the second lens array 51, and overlap lens 52, condenser lens 53, and The light valve 55 is illuminated via the reflection prism 54. This illumination light is spatially modulated by a light valve 55 and is enlarged and projected on a screen 58 by a projection lens 57.
[0036]
Further, in the present embodiment, since the light valve 55 has a single configuration, the light emitting diodes 11R, 11G, 11B, and 11SG are sequentially turned on, and while one light emitting diode is turned on, the other light emitting diodes are not turned on. It is driven to emit light so as to be turned off. That is, the red image, the green image, and the blue image are repeatedly projected onto the screen at a speed of several tens of times or more per second, and are additively mixed by human eyes. Same as 200.
[0037]
The function of the superimposing lens 52 in FIG. 1 is to direct the principal ray of the light beam emitted from the plurality of secondary light sources formed on the second lens array 51 to the light valve 55, and the function of the condenser lens 53 is The main beam of the light beam illuminating the light valve 55 is made to enter the light valve substantially perpendicularly.
[0038]
In the above description, the light emitting diodes of three colors are sequentially turned on. However, the four light emitting diodes may be sequentially turned on. Further, in the present embodiment, green light is constituted by light sources (light emitting diodes) that emit light at two different center wavelengths.
[0039]
As described above, according to the projection device of Embodiment 1, in addition to the conventional three primary colors, the red light emitting diode 11R, the green light emitting diode 11G, and the blue light emitting diode 11B, the second green light emitting diode Since 11 SG can be added, the total radiation amount of the light source can be increased, and thereby the projected light flux on the screen can be increased.
[0040]
Embodiment 2 FIG.
FIG. 2 is a main part configuration diagram schematically showing a main part configuration of a projection device 21 according to a second embodiment having an illumination optical system structure according to the present invention.
[0041]
The main difference between the projection device 21 and the projection device 1 according to the first embodiment shown in FIG. 1 is that a red light source unit 22R, a green light source unit 22G, and a plurality of light emitting diodes and a collimator lens are unitized. The point is that the blue light source unit 22B and the wavelength combining prism 23 are provided. Therefore, the same reference numerals are given to portions of the projection device 21 according to the second embodiment that are common to the projection device 1 according to the first embodiment, and different points will be mainly described.
[0042]
In FIG. 2, reference numeral 22R denotes a red light source unit including a plurality of light emitting diodes 11R that emit red light and a plurality of collimator lenses 19R that collimate divergent light emitted from the light emitting diodes. The green light source unit 22B includes a plurality of light-emitting diodes 11G that emit green light and a plurality of collimator lenses 19G. Similarly, the green light source unit 22B includes a plurality of light-emitting diodes 11B that emit blue light and a plurality of collimator lenses 19B. It is a blue light source unit.
Here, the plurality of light emitting diodes that emit light in the same color in each light source section correspond to one light source here.
[0043]
23 is composed of three triangular prisms, a wavelength synthesizing prism corresponding to wavelength synthesizing prism means, 50 to 58 are a first lens array, a second lens array, a superimposing lens, a condenser lens, a total reflection prism, and a light, respectively. A bulb, an integrator, a projection lens, and a screen, which are the same as the projection device 200 shown as the reference example in FIG. Further, in the projection device 21 having the above configuration, the optical system excluding the total reflection prism 54, the light valve 55, the projection lens 54, and the screen 55 corresponds to an illumination optical system.
[0044]
Next, the operation of the projection device 21 according to the second embodiment will be described.
[0045]
FIG. 3 is a diagram for explaining the operation of the wavelength combining prism 23 shown in FIG. 2, and FIG. 3A is a cross-sectional view showing the optical path relationship between the wavelength combining prism 23 and its input / output light. FIG. 3B is a color synthesis characteristic graph showing the color synthesis characteristics of the wavelength synthesis prism 23. The horizontal axis of the color synthesis characteristic graph indicates the wavelength of the incident light, and the vertical axis indicates the reflectance of the wavelength synthesis prism 23.
Here, it should be noted that the characteristic difference between the S-polarized light and the P-polarized light is very small because the angle of incidence on the dielectric multilayer film is small.
[0046]
The wavelength combining prism 23 includes three triangular prisms 23a, 23b, and 23c, and a dielectric multilayer film is formed on the surfaces 23f and 23g of the two triangular prisms. In the wavelength combining prism 23, a gap of several tens of μm is provided between each of the triangular prisms 23a and 23b and between the triangular prisms 23b and 23c. Then, outgoing light from each of the light source units 22R, 22G, and 22B, which has been made substantially parallel, enters the wavelength synthesizing prism 23.
[0047]
In the color synthesis characteristic graph of FIG. 3B, the measurement curve 26 shows the light reflection characteristic of the surface 23f on which the dielectric multilayer film is formed. From this characteristic, light in the red wavelength region is reflected on this surface 23f. It will be understood that On the other hand, the measurement curve 27 indicates the light reflection characteristics of the surface 23g on which the dielectric multilayer film is formed. From this characteristic, it can be understood that light in the blue wavelength region is reflected on the bonding surface 23g. Further, from these characteristics, it is understood that each of the surfaces 23f and 23g transmits light in a green wavelength region around 500 nm to 550 nm.
[0048]
Therefore, as shown in FIG. 3A, the red light flux entering from below the triangular prism 23b first reaches the interface with the air gap on the right side of the triangular prism 23b, but is totally reflected because the incident angle is large. And reaches the left surface of the triangular prism 23b. Since the dielectric multilayer film that reflects the red wavelength region is formed on the surface 23f as described above, the red light flux is reflected and reaches the sea surface with the gap on the right side of the triangular prism 23b again. .
[0049]
However, this time, since the incident angle is small, the light passes through here and goes to the triangular prism 23c. However, since the dielectric multilayer film formed on the left surface 23g of the triangular prism 23c transmits light in the red wavelength region as shown in the measurement curve 27 (FIG. 13B), the red light flux Passes through the triangular prism 23c and is taken out (to the right in FIG. 3A).
[0050]
Further, as shown in FIG. 3A, the blue light beam incident from above the triangular prism 23c first reaches the interface of the triangular prism 23c, but is totally reflected due to a large incident angle, and is triangular prism. It reaches 23g on the left side of 23c. Since the dielectric multilayer film that reflects the blue wavelength region is formed on the surface 23g as described above, the blue light beam is reflected and reaches the right interface of the triangular prism 23c again. However, this time, since the angle of incidence is small, the light is transmitted therethrough and is taken out (to the right in FIG. 3A).
[0051]
Further, as shown in FIG. 3A, the green light beam incident from the left side of the triangular prism 23a first reaches the joining surface 23f of the triangular prisms 23a and 23b, and as described above, this joining surface 23f Is formed with a dielectric multilayer film that reflects a red wavelength region having a wavelength longer than that of green, so that the green light flux passes therethrough, enters the triangular prism 23b, and travels toward the triangular prism 23c. . Further, since a dielectric multilayer film that reflects a blue wavelength region having a shorter wavelength than green is formed on the joint surface 23g between the triangular prisms 23b and 23c, a green light beam passes through the dielectric multilayer film. The light passes through the triangular prism 23c and is taken out (to the right in FIG. 3A).
[0052]
As described above, the luminous fluxes of the respective colors output on substantially the same optical axis enter the integrator 56 constituted by the first lens array 50 and the second lens array 51 as shown in FIG. The light valve 55 is irradiated through a condenser lens 53, a total reflection type prism 54, and the like. The illumination light is spatially modulated by the light valve, and is enlarged and projected on the screen 58 by the projection lens 57.
[0053]
Further, in the present embodiment, since the light valve 55 has a single structure, the light emitting diodes 11R, 11G, and 11B are sequentially turned on, and while one light emitting diode is turned on, the other light emitting diodes are turned off. become. That is, the red image, the green image, and the blue image are repeatedly projected onto the screen at a speed of several tens of times or more per second, and are additively mixed by human eyes. Same as 200.
[0054]
The function of the superimposing lens 52 in FIG. 2 is to direct the principal ray of the light beam emitted from the plurality of secondary light sources formed on the second lens array 51 to the light valve 55, and the function of the condenser lens 53 is The main beam of the light beam illuminating the light valve 55 is made to enter the light valve substantially perpendicularly.
[0055]
FIG. 4 shows factors that reduce the luminous flux in the optical path from the light emitting diodes 11R, 11G, and 11B, which are the light sources of the light source units 22R, 22G, and 22B, to the screen 58 in the projection device 21 having the above configuration. 6 is a graph summarizing the efficiency and the luminous flux utilization efficiency up to the final screen.
[0056]
The operation of the projection device 21 will be described with reference to the light flux utilization efficiency with reference to the graph of FIG.
[0057]
The red, green, and blue emitted lights emitted from the respective light emitting diodes 11R, 11G, 11B constituting each of the light source units 22R, 22G, 22B are substantially collimated by the respective collimator lenses 19R, 19G, 19B. Each is output as output light of each light source unit. At this time, as in the above-described reference example (FIG. 9), the numerical aperture of each of the collimator lenses 19R, 19G, and 19B is set to sin60 degrees = 0.866, and the light distribution of the light emitted from the light emitting diode is equal to the light emission of the light emitting diode. Assuming that the light is proportional to the cosine of the perpendicular to the surface, 75% of the luminous flux emitted from the light emitting diode can be emitted forward by the collimator lens, that is, from each of the light sources 22R, 22G, and 22B. it can.
[0058]
The three colors of emitted light from the light sources 22R, 22G, and 22B enter the wavelength combining prism 23 and are aligned on substantially the same optical axis by transmission and reflection. From the spectral characteristics of the wavelength synthesizing prism 23, the respective reflectances of S-polarized light and P-polarized light in red (center wavelength: 630 nm) are estimated to be 98%, so that the average reflectance can be assumed to be 98%.
[0059]
Further, since the transmittance of S-polarized light in green (center wavelength: 530 nm) is estimated to be 98% and the transmittance of P-polarized light is also estimated to be 98%, the average transmittance can be assumed to be 98%. Furthermore, since the reflectance of each of S-polarized light and P-polarized light in blue (center wavelength 470 nm) is estimated to be 98%, the average reflectance can be assumed to be 98%.
[0060]
Next, it is assumed that the light use efficiency in each optical path from each collimator lens 19R, 19G, 19B to the projection lens 57 is 67 ± 20%. This is a numerical value determined by the light emitting area and light distribution of each of the light emitting diodes 11R, 11G, and 11B, the area of the digital micromirror array serving as the light valve 55, the numerical aperture of the projection lens 57, and the like. When the light emitting areas of 11G and 11B are small and the area of the digital micromirror array constituting the light valve 55 is large, the value approaches 100%.
[0061]
Further, the effective reflectivity of the digital micromirror array is set to 64%, the loss caused by the irradiation margin by irradiating the digital micromirror array larger than the effective area is 16%, and the transmittance of the total reflection prism 54 is 90%. Loss on the glass-air interface 12 from the entrance surface of the collimator lenses 19R, 19G and 19B to the output surface of the condenser lens 53 and the loss on the glass-air interface 20 of the projection lens (assuming 10 lenses) (0 per surface). Assuming that the transmittance in consideration of 0.5%) is 85.1%, the effective utilization rate of the above three factors is 64.3% (0.84 × 0.9 × 0.851 × 100). Can be.
[0062]
Therefore, as shown in FIG. 2, the ratio of the light beam reaching the screen 58 to the light beam emitted from each of the light emitting diodes 11R, 11G, and 11B is as follows.
0.75 × 0.98 × (0.67 ± 0.20) × 0.64 × 0.643
= 0.203 ± 0.060
That is, it is about 20.3 ± 6.0%, which is about 1.3 to 1.4 times the estimated value in the reference example of FIG.
[0063]
As described above, according to the projection device 21 of the second embodiment, the light use efficiency of the light source can be significantly improved as compared with the conventional projection device using the dichroic prism as the wavelength synthesizing means.
[0064]
Embodiment 3 FIG.
FIG. 5 is a main configuration diagram schematically showing a main configuration of a projection device 31 according to a third embodiment having an illumination optical system structure according to the present invention.
[0065]
The main difference between this projection device 31 and the projection device 21 of the second embodiment shown in FIG. 2 is that a blue-green light source unit 22BG and a second wavelength synthesizing prism 32 associated therewith are added. is there. Therefore, in the projection device 31 of the third embodiment, the same portions as those of the projection device 21 of the second embodiment are denoted by the same reference numerals, and different points will be mainly described.
[0066]
In FIG. 5, like the other light source sections, 22BG includes a plurality of light emitting diodes 11BG that emit blue-green light and a plurality of collimator lenses 19BG that convert divergent light emitted from the light emitting diodes into substantially parallel light. Reference numeral 32 denotes a second wavelength at which the radiated light from the green light source unit 22G and the radiated light from the turquoise light source unit 22BG are respectively incident and emitted on the same optical axis. It is a synthetic prism.
[0067]
The operation of the projection device 31 according to the third embodiment to which the above configuration has been added will be described.
[0068]
First, the second wavelength synthesizing prism 32 is composed of two triangular prisms, and the light in the blue wavelength region is transmitted through the left side surface 32a of the triangular prism on the right side of the drawing and the blue-green wavelength region. Is formed with a dielectric multilayer film that reflects light. An air gap is interposed between these two triangular prisms. The second wavelength synthesizing prism 32 and the wavelength synthesizing prism 23 correspond to wavelength synthesizing prism means.
[0069]
The light emitted from the light source units 22B and 22BG, which has been made substantially parallel, enters the second wavelength combining prism 32. As described with reference to FIGS. 2 and 3, light from the blue-green light source unit 22BG is formed on the left side surface 32a after total reflection at the air boundary surface of the triangular prism in the second wavelength combining prism 32. The reflected light is reflected by the dielectric multilayer film that reflects the blue-green wavelength region. On the other hand, light from the green light source unit 22G passes through the dielectric multilayer film. Accordingly, the light beams of these two incident lights are output on the same optical axis by the second wavelength synthesizing prism, travel to the next wavelength synthesizing prism 23, and pass therethrough.
[0070]
Considering the spectral characteristics of the wavelength synthesizing prisms 23 and 32 (blocking characteristics of about 20 nm), the center wavelength of the light source unit 22B is 470 ± 20 nm, the center wavelength of the light source unit 22G is 530 ± 20 nm, and the center wavelength of the light source unit 22BG is 500. ± 20 nm is desirable. The center wavelength of the light source unit 22R is 630 ± 20 nm. With this setting, as shown in FIG. 6, a color reproduction range in the NTSC system can be almost realized.
[0071]
Further, it is appropriate that the light source units 22R, 22B, and 22BG are the first and the second light source units 22R, 22B, and 22B at the same time. The reason is that by efficiently combining green light and blue-green light, the luminous flux in the green wavelength region, which needs to occupy 65 to 80% of the luminous flux in the visible region, can be further increased.
[0072]
As described above, according to the projection device of the third embodiment, the same effects as those of the second embodiment can be obtained, and the projection image on the screen can be further brightened.
[0073]
In the above embodiment, the light source is assumed to be a light emitting diode. However, the present invention is not limited to this, and a semiconductor laser or an array thereof may be used.
[0074]
Further, in the above-described embodiment, the light emitted from the light source is made substantially collimated by the collimator lens, but is not limited thereto. Various modes can be adopted, such as a configuration for obtaining light.
[0075]
Further, in the description of the above-described embodiment, words such as “up”, “down”, “left”, and “right” are used, but these are for convenience, and are absolute in a state where the proof optical system structure is arranged. It does not limit the relative positional relationship.
[0076]
【The invention's effect】
According to the illumination optical system structure of the first aspect, since a light source other than the three primary colors of red, green and blue can be added, the total radiated light flux of the light source can be increased, thereby supplying a sufficient projection light flux on the screen. it can.
[0077]
According to the illumination optical system structure of the second aspect, the incident angle of the red light beam and the blue light beam to the dielectric multilayer film can be reduced to about 10 degrees in the wavelength combining prism, so that the incident angle to the dielectric multilayer film is reduced. In comparison with the case of 45 degrees, the dependence of the spectral characteristics on the polarization direction can be made extremely small. Furthermore, since the wavelength separation characteristics can be sharper, for example, the wavelength separation interval can be set to about 20 nm, even if the oscillation wavelength of the light emitting diode of each color is widened, the overlap due to the wavelength spread is reduced, and the loss of the luminous flux generated by the light source is reduced. Can be reduced. Therefore, the wavelength combining prism is excellent in reflection efficiency or transmission efficiency regardless of the polarization direction, and can increase the light use efficiency of the light source.
[0078]
According to the illumination optical system structure of the third and fourth aspects, in addition to the same effect as that of the second aspect, the color reproduction range in the NTSC system can be substantially realized, and the projected image on the screen can be brightened. it can.
[0079]
According to the illumination optical system structure of the fifth and sixth aspects, a semiconductor light emitting element such as a light emitting diode or a semiconductor laser is adopted as a light source of each color, and further, only a light beam of a necessary color can be obtained at a required time. In this case, the efficiency of the light source can be increased, and the reliability of the illumination optical system can be increased.
[0080]
According to the projection device of the seventh aspect, it is possible to project an image of a desired brightness on a screen by illuminating the light valve with an illumination optical system which is excellent in utilization efficiency and supplies a sufficient amount of illumination light. A possible projection device can be provided.
[Brief description of the drawings]
FIG. 1 is a main configuration diagram showing a main configuration of a projection device 1 according to a first embodiment having an illumination optical system structure according to the present invention.
FIG. 2 is a main part configuration diagram schematically showing a main part configuration of a projection device 21 according to a second embodiment having an illumination optical system structure according to the present invention.
3A and 3B are diagrams for explaining the function of the wavelength combining prism 23, wherein FIG. 3A is a cross-sectional view showing the optical path relationship between the wavelength combining prism 23 and its input / output light, and FIG. 5 is a color synthesis characteristic graph showing color synthesis characteristics.
FIG. 4 is a graph summarizing the luminous flux utilization efficiencies from the light emitting diodes 11R, 11G, 11B to the final screen in the projection device 21.
FIG. 5 is a main configuration diagram schematically showing a main configuration of a projection device 31 according to a third embodiment having an illumination optical system structure according to the present invention.
FIG. 6 is a diagram provided for describing an operation of a projection device 31 according to the third embodiment.
FIG. 7 is a schematic configuration diagram of a lighting device 100 for explaining the disclosure content described in JP-A-10-269802.
FIGS. 8A and 8B are views for explaining the function of the chromatic prism 106. FIG. 8A is an external perspective view showing the optical path relationship between the chromatic prism 106 and its input / output light, and FIG. 5 is a spectral characteristic graph showing the spectral characteristics of FIG.
FIG. 9 is a configuration diagram showing a configuration of a projection device 200 as a reference example (hence, not a conventional example) for clarifying the effects of the present invention.
10 is a graph summarizing the luminous flux utilization efficiency from a light emitting diode as a light source to a final screen in FIG.
[Explanation of symbols]
Reference Signs List 1 projection device, 2 wavelength combiner, 11R, 11G, 11B, 11BG, 11SG light emitting diode, 19R, 19G, 19B, 19BG, 19SG collimator lens, 21 projection device, 22R, 22G, 22B, 22BG light source unit, 23 wavelength synthesis Prism, 26, 27 measurement curve, 31 projection device, 32 second wavelength synthesis prism, 32a left side surface, 50 first lens array, 51 second lens array, 52 superimposing lens, 53 condenser lens, 54 total reflection prism, 55 light valve digital micromirror array, 56 integrator, 57 projection lens, 58 screen, 100 projection device, 200 projection device.

Claims (7)

An illumination optical system structure of a projection device that irradiates a light valve with a light beam output from a light source and projects an image formed by the light valve onto a screen by a projection lens,
A first light source that emits light with red, green, and blue as central wavelengths, respectively;
A second light source that emits a color having a center wavelength different from each of the center wavelengths of the colors of the first light sources;
An illumination optical system structure for a projection apparatus, comprising: a wavelength synthesizing unit that receives a light flux output from each of the first light source and the second light source and outputs the light flux on substantially the same optical axis. An illumination optical system structure of a projection device that irradiates a light valve with a light beam output from a light source and projects an image formed by the light valve onto a screen by a projection lens,
Each light source that emits red, green, and blue light at the center wavelength,
The light beam input from at least one of the light sources is once totally reflected, reflected by the dielectric multilayer film, and input from another light source and transmitted through the dielectric multilayer film on substantially the same optical axis as the light beams having different wavelengths. An illumination optical system structure of a projection device, comprising: a wavelength synthesizing prism configured to output light. An illumination optical system structure of a projection device that irradiates a light valve with a light beam output from a light source and projects an image formed by the light valve onto a screen by a projection lens,
Each light source that emits light with red, green, blue green, and blue as central wavelengths,
The light beam input from at least one of the light sources is once totally reflected, reflected by the dielectric multilayer film, and input from another light source and transmitted through the dielectric multilayer film on substantially the same optical axis as the light beams having different wavelengths. And a wavelength synthesizing prism means configured to output the light. 4. The illumination optical system according to claim 3, wherein the center value of the emission wavelength of the light source is within a range of 470 ± 20 nm for blue, 530 ± 20 nm for green, and 500 ± 20 nm for blue-green. System structure. 5. The illumination optical system structure of a projection device according to claim 1, wherein said light source comprises a light emitting diode and / or a semiconductor laser. The illumination optical system structure of the projection device according to claim 5, wherein the light sources of the respective colors are driven so as to sequentially emit light. An illumination optical system structure of the projection device according to claim 1,
A light valve that forms a projection image by irradiating a light beam output on the same optical axis,
A projection lens for projecting the projection image onto a screen.

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