JP2004133312A - Light source device and projection display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device which uses a light emitting diode of a single plate type having excellent life characteristic as a light source, has a high efficiency for light utilization and enables satisfactory brightness to be obtained, and to provide a projection type display apparatus which is made compact. <P>SOLUTION: In the light source device and the projection type display device, a micro-mirror type switching device 103 which selectively and time-divisionally reflects luminous fluxes 107, 109 made incident from different directions is used, the luminous fluxes are taken out in the same direction and a time-division luminous flux 505 is formed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light source device using a light emitting diode as a light source and a projection display device.
[0002]
[Prior art]
Conventional projection display devices use discharge lamps such as metal halide lamps and ultra-high-pressure mercury lamps as light sources, and use a thin film with wavelength selectivity such as a dichroic mirror or dichroic prism to convert the white light generated by these light sources. The light is divided into red (R), green (G), and blue (B) wavelength components by a filter, and these lights are radiated to the corresponding liquid crystal panel, and the radiated lights are again synthesized by a dichroic prism or the like. A projection-type liquid crystal display device that performs enlarged display on a screen or the like via a projection lens is known. In this type of projection type liquid crystal display device, a three-panel type, which uses three liquid crystal panels for red, green, and blue, which are display devices of a two-dimensional optical modulator, is mainly used.
[0003]
There is also a single-panel projection display apparatus using one digital mirror device (DMD) instead of a liquid crystal panel as a display device. In this single-panel system, a white light source such as an ultra-high pressure mercury lamp is used as a light source, as in the above-mentioned three-panel projection type liquid crystal display device. This white light is time-divided using a rotating color filter disk. And irradiates one pixel sequentially with red, green, and blue light. In particular, the DMD is a display element having excellent response speed, is a bistable element that switches between ON and OFF states, and gradation expression is realized by PWM (pulse width modulation) control, that is, by changing the ON time. You.
[0004]
By the way, application of a solid-state light source instead of a white discharge lamp that has been used as a light source has been studied (see Patent Documents 1 and 2). In recent years, the development of light-emitting diodes has been remarkable, and blue and green light-emitting diodes with high luminance and high efficiency have also appeared. By combining them with red light-emitting diodes, which were relatively high in luminance and high in efficiency, projection display devices The possibility of realizing this light source has emerged.
[0005]
The above-mentioned light-emitting diode is very promising for a projection display device because it has many advantages such as 1) low power consumption, 2) durable and compact, and 3) long life. In particular, regarding the life, a conventional high-pressure mercury lamp is generally said to have a life of 2,000 to 3,000 hours, whereas a light emitting diode has a life of tens of thousands of hours. Further, when a single color light source of red, blue, and green is used as the light source device of the projection display device, there is an advantage that infrared light and ultraviolet light are not generated.
[0006]
Further, as a conventional example, a plurality of light sources are sequentially turned on in a time-division manner, and the optical paths of light from the respective light sources are sequentially merged into a common optical path by an optical path switching device that switches between reflection and transmission. There is a light source device and a projection type image display device that have a reflection area and a transmission area on one disk, and use a rotating mirror or the like that switches between reflection and transmission by rotation (for example, see Patent Document 3).
[0007]
[Patent Document 1]
JP-A-11-32278 (pages 1-4, FIG. 1)
[Patent Document 2]
JP 2001-343706 A (pages 1-4, FIG. 2)
[Patent Document 3]
JP-A-2000-89139 (pages 1-4, FIG. 1)
[0008]
[Problems to be solved by the invention]
However, in the above-mentioned conventional projection display apparatus, the three-panel method has a disadvantage that the cost of the entire apparatus is increased. In addition, since the single-panel type requires only one display element, it is advantageous in terms of cost and size as compared with the above-mentioned three-panel type projection type liquid crystal display device. There is a disadvantage that the brightness on the projection screen is reduced because / 3 is lost by absorption or reflection.
[0009]
In addition, any of the above-described conventional projection display apparatuses requires an optical element (a dichroic mirror or a color filter disk) for dispersing the white light source light into R, G, and B light. In addition, the light-emitting component of the white light source includes infrared light and ultraviolet light that are not necessary for image display, and an infrared cut or ultraviolet cut optical filter for removing these light is also required. In particular, the infrared light component is discharged to the outside of the device using a fan or the like, but it is difficult to completely discharge the infrared light component from the device covered with the exterior. This causes the temperature of the display device to rise. In particular, in the case of a liquid crystal panel, when the ambient temperature of the liquid crystal panel generally exceeds 70 ° C., there is a problem that the display quality is significantly reduced.
[0010]
In addition, there is an ultraviolet light component that cannot be completely removed by the ultraviolet cut optical filter, and this light seriously damages the liquid crystal panel. The organic alignment film constituting the liquid crystal panel has the property of deteriorating due to irradiation with ultraviolet light, which is a drawback in that the display quality is reduced.
[0011]
If a light source device that emits these lights in the same direction in a time-division manner using R, G, and B monochromatic light sources having only light-emitting components necessary for image display can be realized, An optical element and an optical filter are not required, and there is no need to worry about deterioration of image quality, and it is possible to realize a projection-type display device that requires only simple cooling, in which deterioration of internal optical components and display devices due to heat rays or ultraviolet rays is improved. In addition, the light use efficiency is high and the size can be reduced.
[0012]
Further, in the light source device, the luminous efficiency per light emitting diode lamp which can be easily obtained as a general-purpose product at present is about 10 to 40 Lm / W (lumen / watt), and a conventional high pressure light source having 60 Lm / W or more. It is far below the luminous efficiency of a mercury lamp. Therefore, it is effective to increase the number of light emitting diodes and secure the luminance in order to obtain practical luminance using the light emitting diodes as a light source. For example, it is conceivable to use a plurality of light emitting diodes arranged in an array. However, even if a plurality of the discharge lamps are arranged, the demand for high luminance, which is a performance requirement of the projection display device, does not reach the level of using a conventional discharge lamp.
[0013]
Further, in the conventional switching device described in Patent Document 3, when three or four light source portions are used, two rotating mirrors are required, which increases the size of the light source device and complicates the rotation control. There's a problem.
[0014]
The present invention has been made in view of the above circumstances, a single-panel type that is advantageous for miniaturization, and in a projection display device using a light emitting diode with excellent life characteristics as a light source unit, the light use efficiency is high. It is an object of the present invention to provide a light source device capable of obtaining good luminance and a small projection display device.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the light source device according to the first aspect of the present invention includes a plurality of light emitting diode light sources that emit light of different colors that can be pulsed, and the same by selectively reflecting light beams from the plurality of light emitting diode light sources. And a reflecting element that joins the optical path.
[0016]
A light source device according to a second aspect is characterized in that, in the light source device according to the first aspect, a plurality of light emitting diode light sources are made to enter the reflective element from different directions.
[0017]
According to a third aspect of the present invention, in the light source device according to the first aspect, the light emitting diode light source emits red, blue, and green light.
[0018]
According to a fourth aspect of the present invention, in the light source device according to the first aspect, the reflection element is a micromirror type optical switch having at least two inclined states, and the reflection element is synchronized with lighting of a plurality of light emitting diodes. It is characterized in that the reflection surface of the mirror type optical switch is switched.
[0019]
According to a fifth aspect of the present invention, in the light source device according to the first aspect, the light emitting diode light source includes a plurality of light emitting diodes arranged in an array.
[0020]
The light source device according to claim 6 is the light source device according to claim 4, wherein the micromirror type optical switch is at least one of a silicon micromachine, a digital mirror device, a galvano micromirror, and a micromirror array. And
[0021]
According to a seventh aspect of the invention, there is provided a projection display apparatus including the light source device according to the first to sixth aspects, a two-dimensional light modulator, and a projection lens, and performing color display in a time-division manner.
[0022]
According to an eighth aspect of the present invention, there is provided the projection type display device according to the seventh aspect, further comprising any one of a digital mirror device and an LCOS reflection type device as a display device.
[0023]
With the above configuration, for example, each light beam from the light source 1 including the red and blue light emitting diodes and the light source 2 including the green light emitting diode located in different directions corresponds to the tilt state of the reflection element. It is reflected and then merges in the same direction, so if you look at the merged luminous flux in time, you can get a red, blue, and green repeated luminous flux. The light source unit of the device can be configured.
[0024]
Here, the light beam from the light source 1 and the light beam from the light source 2 are turned on in synchronization with the first tilt state and the second tilt state of the micromirror type optical switch. The red light emitting diode and the blue light emitting diode are sequentially turned on and off within the time period of the first tilt state of the micromirror. Generally, unlike a discharge lamp, a light emitting diode is capable of pulse lighting as well as continuous lighting. In particular, in pulse lighting, by setting the duty ratio to a predetermined value, it is possible to easily increase the output while keeping the power consumption constant. Therefore, it is possible to perform a lighting control in which the green LED in the first tilt state or the red and blue light emitting diodes in the second tilt state is turned off, that is, the state not selected by the tilt state of the micromirror, ie, the first tilt state. is there. Therefore, the same amount of light as when all the light emitting diodes are turned on can be maintained, and the light utilization rate can be increased.
[0025]
As the micromirror-type optical switch, for example, there is a silicon micromachine in which a movable portion is electrostatically displaced by micromachining a silicon substrate. The silicon micromachine may be a microhinge type micromachine in which a movable part is connected to a main body by a hinge part, and the movable part can rotate around the hinge. It is also possible to use two inclined states of the DMD. Further, a well-known technique such as an electrostatic drive type galvano micromirror used for controlling a light beam irradiation position of an optical disk device described in Japanese Patent Application Laid-Open No. 2001-249286 “Galvo Micromirror and Manufacturing Method Thereof”. Can also be used. In addition, a micromirror array for switching optical signals described in Japanese Patent Application Laid-Open No. 2001-242396, “Micromachine Constituting Optical Switch Using Biaxial Micromirror” may be used. The inclined state of the micromirror may be three places or four places in addition to two places. In the case of three places, the three inclined states may be assigned to the luminous flux from the red, blue, and green light-emitting diodes, respectively, and in the case of four places, each of the three states may be used for red, blue, green, and white. A light emitting diode light source may be provided to control the tilt state of the micromirror and the lighting timing of each light emitting diode light source.
[0026]
In addition, a plurality of light emitting diode light sources for each color may be arranged in an array. Since the light output of the light source increases according to the number of light emitting diodes, the brightness is increased. In addition, by configuring a projection display device with the light source device, the two-dimensional light modulator, and the projection lens, a single-plate projection display device that performs time-division color display can be realized. In particular, a DMD is preferable for a display device, but an LCOS reflection type device using a ferroelectric liquid crystal or the like having an excellent response speed may be used.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying screens. The embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. It is not limited to these forms unless otherwise stated.
[0028]
FIG. 2 and FIG. 3 are diagrams for explaining the principle of the light source device according to the first preferred embodiment of the present invention. 2 and 3, a light emitting diode 104 having a red emission wavelength and a light emitting diode 105 having a blue emission wavelength are used as the first light source 101. In addition, a light emitting diode 106 having a green emission wavelength was used as the second light source 102. As the reflective element 103, a micromirror type optical switch having two inclined states was used. This optical switch is driven by an electrostatic force like a DMD, for example, and has two stable positions inclined at an angle of ± θ with respect to the rotation axis.
[0029]
In FIG. 2, light 107 from the first light source enters at an angle of 2θ from the upper left corresponding to the first tilt state of the micromirror 103 (eg, + θ-degree tilt, solid line in the figure). The light beam 108 is reflected right above the micromirror 103 and emitted from the light source device. Similarly, as shown in FIG. 3, the light 109 from the second light source 102 has an angle of 2θ from the upper right corresponding to the second tilt state of the micromirror 103 (eg, −θ degree tilt, solid line in the figure). Incident. The light 108 reflected by the micromirror 103 is similarly emitted light from the light source device heading directly upward. Here, after the light from both the first light source 101 and the second light source 102 is reflected by the micromirror 103, it becomes the light source device emission light 108 following the same path.
[0030]
Here, assuming that the times when the reflection element 103 is in the first inclined state and the second inclined state are T and T ′, respectively, a red or blue light beam is selected in the period of T time, and green in T2 time. Is selectively reflected. Then, within the T time, for example, if the first T / 2 time is assigned to the lighting of the red light emitting diode and the remaining T / 2 time is assigned to the lighting of the blue light emitting diode 104, the light source device is provided at the time of T + T '. , A continuous light flux in which red, blue, and green are sequentially repeated in one cycle of red → blue → green is obtained, and this is used as illumination light to synchronize the two-dimensional light modulator 502 shown in FIG. By performing the control, time-division color image display becomes possible.
[0031]
FIG. 4 is a diagram showing the timing of turning on and off the red, blue, and green light emitting diodes (104, 105, and 106 shown in FIGS. 2 and 3). First, the red light emitting diode 104 is turned on in the first micro mirror tilt state. When the time T / 2 has elapsed, the red light emitting diode 104 is turned off, and at the same time, the blue light emitting diode 105 is turned on. After a lapse of T / 2, the blue light-emitting diode 105 is turned off, and the micromirror 103 switches to the second inclined state. At the same time, the green light emitting diode 106 is turned on for the time T '. Therefore, if two tilts of the micromirror 103 are one cycle, a light flux of red → blue → green is formed repeatedly.
[0032]
Further, it is also possible to take on / off timings as shown in FIG. The difference from the turning on / off timing shown in FIG. 4 is that the T time is assigned to the turning on time of the red or blue light emitting diode in the first tilt state of the micro mirror 103. In the first micromirror tilt state, first, the red light emitting diode 104 is turned on for T hours. Then, when the time T has elapsed, the red light emitting diode 104 is turned off, and the micro mirror 103 switches to the second inclined state. At the same time, the green light emitting diode 106 is turned on for the time T '. Thereafter, when the first inclined state is reached, the blue light emitting diode 105 is turned on. Then, after the elapse of the time T, the state shifts to the second inclined state, and a cycle is formed in which the blue light emitting diode 105 is turned off and the green light emitting diode 106 is turned on for the time T '. In this way, a light beam that repeats in time of red → green → blue → green is formed.
[0033]
In many cases, the red, blue, and green light-emitting diodes do not have the same light output (different luminous efficiencies). In order to improve the white balance of the light flux obtained by the light source device, the light-emitting diodes are turned on. It is sufficient to set a predetermined time and a predetermined applied current at the time of lighting. It is also possible to prepare a large number of light-emitting diodes to be used and use them in an array. In that case, a high-luminance luminous flux is obtained according to the number of light-emitting diodes used.
[0034]
FIG. 1 is a diagram showing a configuration of a projection display device using the light source device of the present invention. The projection display device of the present invention includes the light source device 501 described in the embodiment, a reflective two-dimensional light modulator 502, a prism 503, and a projection lens 504. DMD was used for the reflection type two-dimensional modulator 502. In addition, a prism 503 utilizing total reflection is used to make the light modulated by the DMD incident on the projection lens. The prism 503 is a well-known technique used in a projection display device using a DMD.
[0035]
The illumination light beam 505 formed by the light source device 501 and having one cycle of red → green → blue → green enters the DMD 502 via the prism 503. In the DMD, a reflected light 506 light-modulated in synchronization with each color of the illumination light beam 505 is enlarged and projected through a projection lens 504 to obtain a color image.
[0036]
As described above in the embodiment, the light source device and the projection display device according to the present invention use the light emitting diode as the light source, so that the luminous flux component generated by the light source device has no infrared / ultraviolet light component, and the There is no need for an optical filter for removing infrared / ultraviolet light components, which is provided in the projection display device. Further, even if a rotary color filter disk is not used, time-division color illumination light is formed, so that the light source device becomes compact.
[0037]
【The invention's effect】
According to the light source device of the present invention, a plurality of light emitting diode light sources exhibiting different light emission colors capable of pulse lighting and a reflecting element for selectively reflecting light beams from the plurality of light emitting diode light sources and joining them to the same optical path. Therefore, it is possible to efficiently form a time-division illumination light beam.
[0038]
According to the light source device of the second aspect, in the light source device of the first aspect, a plurality of light emitting diode light sources are made to enter the reflective element from different directions, so that time-division illumination is efficiently performed. A light beam can be formed.
[0039]
According to the light source device of the third aspect, in the light source device of the first aspect, since the light emitting diode light source emits red, blue, and green light, the time-division illumination light flux can be efficiently emitted. Can be formed.
[0040]
According to the light source device of the fourth aspect, in the light source device of the first aspect, the reflection element is a micromirror-type optical switch having at least two inclined states, and is synchronized with lighting of the plurality of light emitting diodes. Since the reflecting surface of the micromirror type optical switch is characterized by switching, it is possible to control the lighting of the light emitting diodes, to maintain the same light quantity as when all the light emitting diodes are lit, and to improve the light use efficiency. Can be enhanced.
[0041]
According to the light source device of the fifth aspect, in the light source device of the first aspect, the light emitting diode light source is characterized in that a plurality of light emitting diodes are arranged in an array, so that the light output of the light source unit is increased. Is easy, and high brightness can be achieved.
[0042]
According to the light source device of the sixth aspect, the light source device of the sixth aspect is the light source device of the fourth aspect, wherein the micro mirror type optical switch is a silicon micro machine, a digital mirror device, a galvano micro mirror, a micro mirror. Since at least one of the arrays is characterized, the configuration can be selected and the convenience can be improved.
[0043]
According to a seventh aspect of the invention, a projection display apparatus includes the light source device according to the first to sixth aspects, a two-dimensional light modulator, and a projection lens, and performs color display in a time-division manner. An optical projection display device which is compact and has excellent life characteristics can be realized.
[0044]
The projection display device according to claim 8 is characterized in that, in the projection display device according to claim 7, the display device further includes one of a digital mirror device and an LCOS reflection device as a display device. A configuration can be selected, and convenience can be achieved.
[0045]
As described above, in the light source device and the projection display device according to the present invention, the light beams can be extracted in the same direction by using the switching device of the micromirror type that selectively reflects the light beams incident from different directions in a time-division manner. This makes it possible to form a time-division illumination light flux efficiently. Further, since the light source is provided with a monochromatic light emitting diode, an optical filter for spectral separation is not required, and a compact projection display device having an optical system can be realized. In particular, since the light emitting component of the light emitting diode used in the light source device of the present invention does not include infrared or ultraviolet components, the temperature inside the device does not rise, and the display device is not damaged. Further, a projection display device having excellent life characteristics can be realized. Furthermore, by mounting a large number of light-emitting diodes as light sources on a substrate and forming them in an array, it is easy to increase the light output of the light source unit, and high luminance can be achieved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a projection display device using a light source device of the present invention.
FIG. 2 is a diagram for explaining the principle of the light source device of the present invention.
FIG. 3 is a diagram for explaining the principle of the light source device of the present invention.
FIG. 4 is a diagram for explaining lighting timing of a light emitting diode in the light source device of the present invention.
FIG. 5 is a diagram for explaining lighting timing of a light emitting diode in the light source device of the present invention.
[Explanation of symbols]
101 first light source 102 second light source 103 reflective element (micro mirror)
104 red light emitting diode 105 blue light emitting diode 106 green light emitting diode 107 incident light beam 108 reflected light beam 109 incident light beam 501 light source device 502 two-dimensional light modulator 503 prism 504 projection lens 505 illumination light beam 506 modulated light beam

Claims (8)

A plurality of light emitting diode light sources exhibiting different emission colors capable of pulsed lighting,
A reflecting element for selectively reflecting light beams from the plurality of light-emitting diode light sources and joining the same light path,
The light source device, wherein the reflection element is a micromirror-type optical switch having at least two inclined states. The light source device according to claim 1, wherein the plurality of light emitting diode light sources are made to enter the reflective element from different directions. The light source device according to claim 1, wherein the plurality of light emitting diode light sources emit red, blue, and green light. The light source device according to claim 1, wherein the micromirror-type optical switch switches a reflection surface in synchronization with lighting of the plurality of light emitting diode light sources. The light source device according to claim 1, wherein the light emitting diode light source includes a plurality of light emitting diodes arranged in an array. The light source device according to claim 4, wherein the micromirror-type optical switch is at least one of a silicon micromachine, a digital mirror device, a galvano micromirror, and a micromirror array. A light source device according to claim 1,
A projection display device comprising a two-dimensional light modulator and a projection lens, and performing color display in a time-division manner. The projection display device according to claim 7, further comprising any one of a digital mirror device and an LCOS reflection device as the display device.

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