JP4564757B2 - Light source device and projection display device - Google Patents

Description

  The present invention relates to a light source device for a projection display device and a single-plate projection display device that includes the light source device and uses a DMD panel as a display element.

  The luminous flux from the high-intensity white light source is separated into R (red), G (green), and B (blue) wavelength regions, and the corresponding R, G, and B liquid crystal panels are irradiated with these color lights. In addition, a projection type liquid crystal display device that combines R, G, and B images modulated by a liquid crystal panel with a dichroic prism and enlarges and projects them using a projection lens has been put into practical use. Also, by using one DMD (digital mirror device) instead of a liquid crystal panel as a display element, rotating a disk-shaped disk on which R, G, and B filters are formed with light beams from a high-intensity white light source. A single-plate projection display apparatus that repeatedly generates color light of R → G → B, irradiates this light to the DMD, modulates the DMD, and enlarges and projects a color image by a color sequential method has been put into practical use. Yes. Both disclosed technologies have a common point in that a high-intensity white light source of a discharge lamp is used.

  Although not yet put into practical use, there is also a proposal for a projection display device that uses a light source other than a discharge lamp. For example, a light emitting diode is used as a light source. The light-emitting diode has characteristics that are not possessed by conventional discharge lamps that emit high-intensity white light, such as low cost, long life, and low power consumption, and is promising as a light source for a projection display device.

  Referring to Patent Document 1, three planar light source arrays each including a group of light emitting diodes that emit light of three colors R, G, and B are prepared, and these light source arrays are shared by a dichroic prism. A light source device that emits light and irradiates a liquid crystal panel with a light beam from the light source device. Here, there is one liquid crystal panel, and a color image can be obtained by a color sequential display method with a single-plate configuration. When a low-cost projection display apparatus is to be realized, the fact that only one display panel is required causes a great cost merit. Further, the method of arranging the light source array in a U-shape so as to surround the dichroic prism and synthesizing the light beam can greatly reduce the size of the entire display device because the light source device can be made compact. As far as the present applicant knows, it is most advantageous to arrange the light sources in a U-shape as a method of synthesizing the light beams from the three color light sources in a compact configuration.

  By the way, some considerations are required in using a light emitting diode as a light source of a projection display device. First, although the light emitting diode has characteristics close to those of a discharge lamp in terms of luminous efficiency, it can be said that the amount of a single luminous flux is small. In a projection display apparatus that has been put into practical use, for example, a discharge lamp having an optical output exceeding 6000 Lm (lumen) with a power of 100 W is used. On the other hand, even what is currently known as a light emitting diode that emits the largest luminous flux has a light output of about 120 Lm at most, which is far from the light output of the discharge lamp. Therefore, it is inevitable to use a large number of light emitting diodes when trying to obtain a large output light beam from the light source device. Although a single light-emitting diode is small, the use of a large number of light-emitting diodes causes an increase in the size of the light source, which is against the demand for compactness.

  Therefore, it is necessary to consider using the luminous flux from one light emitting diode as efficiently as possible. Or you should avoid the enlargement of a light source device by arranging a light emitting diode as closely as possible. It is also important that the light beam emitted from the light emitting diode usually has a random polarization component. That is, when a projection type liquid crystal display device using a TN liquid crystal panel or the like as a display device is configured, the light beam emitted from the light source device is preferably linearly polarized light. About half of the light beams of random polarization components emitted by the light emitting diodes are not used for illumination of the liquid crystal panel, which is not preferable in terms of light utilization.

Accordingly, it is desirable to increase the light utilization efficiency by providing a polarization conversion optical system between the light source array and the cross dichroic prism and using a light beam whose polarization is unified in advance. For example, as disclosed in Patent Document 2, if a polarization conversion optical system including a polarization beam splitter array having a half-wave plate is used, random polarized light from a light-emitting diode is efficiently converted into linearly polarized light. As a result, the light utilization rate can be increased.
Japanese Patent No. 3319438 JP 2002-244 211 A

  However, the configuration disclosed in Patent Document 2 causes difficulty when it is desired to provide a large number of light emitting diodes. This is because a polarization conversion optical system composed of a polarization beam splitter having a half-wave plate that is about twice as large as the size of one light-emitting diode is compatible. The interval cannot be approached to the limit. That is, when a large number of light emitting diodes are used, there is a problem that the light source portion becomes large.

  Since the light source unit is disposed so as to surround the dichroic prism in a U-shape, the increase in the size of the light source unit also increases the size of the dichroic prism, leading to an increase in the size of the entire apparatus. In particular, increasing the size of the cross die quick prism made of optical glass is not preferable in all aspects, such as cost increase, weight increase, and non-compact.

  If the display panel is not a liquid crystal panel but a DMD panel, it is not necessary to use linearly polarized light as illumination light, so there is no need to provide a polarization conversion optical system. In this case, light is incident on the dichroic mirror at about 45 degrees. If it does so, the influence of a polarization characteristic will come out and it will cause the fall of a light utilization factor. In other words, this is because, in principle, it is impossible to match the transmission / reflection characteristics of the P-polarized component and the S-polarized component with respect to the incident light beam of 45 degrees. Therefore, there is room for improvement in applying the configuration shown in Patent Document 1 to a case where the display panel is a DMD.

  An object of the present invention is to provide a light source device having a high light utilization rate without causing an increase in the size of the light source even when a large number of light emitting diodes are used as the light source, and is small, lightweight, high brightness, and low cost. In particular, the present invention provides a light source device for a projection display device in which the display device uses random polarized light such as DMD, and a projection display device using the light source device.

The light source device of the present invention comprises:
A first light emitting diode that emits first color light, a second light emitting diode that emits second color light, a third light emitting diode that emits third color light, and the first to third color lights are combined. In a light source device equipped with a color synthesis optical system for
The color synthesizing optical system includes three types of dichroic mirrors having different wavelength selectivity, each having a quarter wavelength plate , and a polarization beam splitter, and the quarter wavelength plate is close to the polarization beam splitter. Is located on the side ,
Three types of the dichroic mirrors are arranged in a U shape at a position that forms an angle of 45 degrees with respect to the polarization separation surface of the polarization beam splitter,
The first to third light emitting diodes are provided in proximity to each of the dichroic mirrors, and light beams from the first to third light emitting diodes are combined into one optical path and emitted. And

The first color light R color, color second color light G, it is not preferable third color light is B-color.

  The characteristic of the dichroic mirror disposed between the first light emitting diode and the polarization beam splitter has a characteristic of transmitting the color light of the first light emitting diode and reflecting the color light of the second and third light emitting diodes. The characteristics of the dichroic mirror disposed between the second light emitting diode and the polarization beam splitter have characteristics of transmitting the color light of the second light emitting diode and reflecting the color light of the first and third light emitting diodes. The characteristic of the dichroic mirror disposed between the third light emitting diode and the polarization beam splitter is that the color light of the third light emitting diode is transmitted and the color light of the first and second light emitting diodes is reflected. You may have.

  The polarizing beam splitter may be a polarizing beam splitter having a structure in which right angle prisms made of two optical glasses each having a dielectric multilayer film formed on a hypotenuse are bonded together, or a flat polarizing beam splitter. Good. The quarter wavelength plate and the dichroic mirror may be provided independently or may be formed integrally.

The projection display device of the present invention is
The light source device described above is provided, a light beam from the light source device is irradiated onto a single DMD display panel, and an image modulated by the DMD display panel is enlarged and displayed by a projection lens.

  According to the present invention, there is an effect that a light source device having a high light utilization rate can be configured. This is a P-polarized light in which light-emitting diodes emitting the first to third color lights are arranged in a U-shape with respect to the polarization beam splitter, and most of the randomly polarized light from the light-emitting diodes is orthogonal in vibration direction. This is because light and S-polarized light can be emitted from the light source device.

  Moreover, according to this invention, there exists an effect that the light source device of a high output can be provided. This is because there is no polarization conversion means for unifying the light flux from the light emitting diodes, so that a large number of light emitting diodes can be arranged closely.

  Furthermore, the projection display device of the present invention has an effect that the entire display device becomes compact. This is because the projection display device is configured by combining the light source device of the present invention and a single DMD as a display panel, so that the light source device becomes small and the entire display device becomes compact.

  Embodiments of a light source device and a projection display device of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic plan view showing a configuration of a light source device according to a first embodiment of the present invention. A light source device 100 includes a light emitting diode (R) 101 that emits R color and a light emitting diode (R) that emits G color ( G) 102 and a light emitting diode 103 (B) emitting B color are arranged in a U-shape, and dichroic mirrors 104, 105, 106 and quarter wave plates 107, 108, 109 are arranged on the emission side of each light emitting diode. And. Further, the polarization beam splitter 110 is arranged so that the optical axis of each of the light emitting diodes 101, 102, and 103 and the polarization separation surface 111 of the polarization beam splitter 110 are at an angle of about 45 degrees.

  As the light emitting diodes 101, 102, and 103, a general light emitting diode such as a shell type or a chip type that is available as a commercial product may be used. In the plan view of FIG. 1, four light emitting diodes are schematically drawn for the sake of space, but the number of light emitting diodes may be provided as necessary. For example, a plurality of light emitting diodes may be arranged on a vertical × horizontal matrix. Can be arranged in a plane.

  The dichroic mirrors 104, 105, and 106 were formed by forming a dielectric multilayer film on a glass substrate by vacuum deposition. As this type of dichroic mirror, a well-known technique put into practical use for an optical component of a projection type liquid crystal display device may be used. The quarter-wave plates 107, 108, and 109 have a structure in which a film type is attached to a glass substrate. In addition to the film type, it is also possible to use a quarter wave plate made of crystals such as quartz.

  The polarizing beam splitter 110 used was a laminate of right-angle prisms made of two optical glasses having a dielectric multilayer film formed on the hypotenuse. Visible random polarized light incident on the polarization separation surface at about 45 degrees is separated into P-polarized light and S-polarized light at a ratio of about 1: 1.

  Next, the operation of the light source device 100 of the present invention will be described with reference to FIGS. 2 (a), (b), (c) and FIG. 2A and 2B are schematic explanatory views for explaining the operation of the light source device of the present invention. FIG. 2A is a schematic view showing an optical path of a light beam emitted from the light emitting diode (R) 101, and FIG. 2B is a light emitting diode (G). ) Is a schematic diagram showing the optical path of the light beam emitted from 102, (c) is a schematic diagram showing the optical path of the light beam emitted from the light emitting diode (B) 103, and FIG. 3 is a dichroic mirror of the light source device 100 of the present invention. It is explanatory drawing which shows the characteristic. Here, each luminous flux is displayed by enclosing the code in parentheses.

  As shown in FIG. 2A, a light beam having a random polarization component is emitted from the light emitting diode (R) 101 that emits light of R color. This light beam first enters the dichroic mirror 104 disposed immediately after the emission position of the light emitting diode (R) 101. The dichroic mirror 104 is formed with a thin film having a characteristic of transmitting R color light and reflecting G and B color light as indicated by characteristic (R) 301 in FIG. Accordingly, the R-color light beam passes through the dichroic mirror 104 and further passes through the quarter-wave plate 107. At this time, even if random polarized light is incident on the quarter-wave plate, the polarization component remains random. Next, the randomly polarized light (211) reaches the polarization separation surface 111 of the polarization beam splitter 110, and at this time, the P-polarized component (213) travels straight in the direction of the B light emitting diode (B) 103. move on. The S-polarized component (212) is reflected and changes the traveling direction toward the G light emitting diode (G) 102. Thereafter, the light beam (213) of the P-polarized component reaches the ¼ wavelength plate 109, temporarily becomes circularly polarized light, and reaches the dichroic mirror 106 arranged on the emission side of the B light emitting diode (B) 103. The dichroic mirror 106 is formed with a thin film having the characteristic of reflecting the G and R colors as shown by the characteristic (B) 303 in FIG. 3, and the R light beam (213) is reflected by the dichroic mirror 106. Therefore, the path is reversed to the R light emitting diode (R) 101 side. Since this path reversal immediately passes through the quarter-wave plate 109, the light beam that was circularly polarized at this time becomes S-polarized light (215). The light beam (215) that has become S-polarized light reaches the polarization separation surface 111, and then is reflected in the direction in which the light beam is emitted from the light source device 100 to become a light beam (216).

  On the other hand, the S-polarized light beam (212) reflected by the polarization separation surface 111 and traveling toward the G-color light emitting diode (G) 102 side reaches the quarter-wave plate 108 and then becomes circularly polarized light. Reflected by the dichroic mirror 105 of the characteristic (G) 302 of FIG. 3 that transmits the color and reflects the R and B colors. Then, the path is changed again to the polarization separation surface 111 side, transmitted through the quarter-wave plate 108, where it is converted to P-polarized light (214), travels straight on the polarization separation surface 111, and is emitted from the light source device 100. It becomes a light beam (217).

  As described above, most of the R-color random polarized light (211) emitted from the light-emitting diode becomes a light beam emitted from the light source device 100 as P-polarized light (217) or S-polarized light (216), and thus the light utilization rate. High light source device 100 can be configured.

  Random polarized light from the light emitting diode (G) 102 that emits G color is emitted from the light source device 100 along the following path. As shown in FIG. 2B, first, the light passes through the dichroic mirror 105 of the characteristic (G) 302 of FIG. 3 that transmits the G color and reflects the B and R colors, and the quarter wavelength plate 108. Then, the light reaches the polarization separation surface 111 with the random polarized light (221). Here, the light beam of the P-polarized component travels straight on the polarization separation surface 111 and becomes emitted light (222) from the light source device 100. The S-polarized light beam 223 reflected by the polarization separation surface 111 is a quarter-wave plate 107 on the R light emitting diode (R) 101 side, and the characteristics shown in FIG. R) 301 reaches the dichroic mirror 104, is reflected there, passes again through the quarter-wave plate 107, and passes through the polarization separation surface 111 as a light beam of P-polarized light, and then passes through the polarization separation surface 111 to the B-color light emitting diode (B) 103 side The dichroic mirror 106 is reached via the ¼ wavelength plate 109. The dichroic mirror 106 has the characteristic (B) 303 of FIG. 3 that reflects the G color, and is converted into S-polarized light (225) by the quarter-wave plate 109 after reflection. After that, the light is reflected by the polarization separation surface 111 and becomes light emitted from the light source device 100 (226).

  Further, random polarized light from the light emitting diode 103 emitting B color is emitted from the light source device 100 along the following path. As shown in FIG. 2C, first, the luminous flux (231) transmits the B color and reflects the G and R colors. The dichroic mirror 106 of the characteristic (B) 303 in FIG. 109, and reaches the polarization separation surface 111. Here, the S-polarized light beam (232) is reflected and emitted from the light source device 100. On the other hand, the P-polarized light beam (233) transmitted through the polarization separation surface 111 passes through the quarter-wave plate 107 disposed on the R-color light emitting diode (R) 101 side, and is reflected by the dichroic mirror 104 that reflects the B color. The light is reflected, passes through the quarter-wave plate 107 again, reaches the polarization separation surface 111 as an S-polarized light beam (234), and is reflected and reflected as a light beam (235) toward the G light emitting diode (G) 102 side. proceed. After that, the light passes through the quarter-wave plate 108, is reflected by the dichroic mirror 105 having the characteristic (B) 303 that reflects B color, is again converted into P-polarized light through the quarter-wave plate 108, and the polarization separation surface. 111 is transmitted through the light source device 100 as a light beam (236).

  As described above, even if the light sources of the R, G, and B light emitting diodes are arranged in a U-shape, it is possible to emit most of the light flux generated by the light source from the light source device 100, and thus a highly efficient light source device. 100 can be configured. In addition, since it is not necessary to newly provide a polarization conversion optical system after emission of the light emitting diode, it becomes possible to use a large number of light emitting diodes and arrange them as close as possible. The light source device 100 that can output can be realized.

  The light source device 100 of the present invention can be variously modified in addition to the first embodiment. For example, in the first embodiment, the dichroic mirrors 104, 105, and 106 and the quarter-wave plates 107, 108, and 109 are independently arranged with respect to the polarization beam splitter 110. It is also possible. The integrated type improves assembly and facilitates handling.

  Yet another modification is shown in FIG. FIG. 4 is a schematic plan view showing the configuration of a modification of the first embodiment of the light source device of the present invention. In the light source device 400, a plurality of light emitting diodes 401, 402, and 403 that emit R, G, and B colors each including a plurality of light emitting devices are arranged in a U-shape, and the optical axis and polarization separation surface of each light emitting diode are approximately equal. A polarizing beam splitter 414 is arranged so as to have an angle of 45 degrees. Further, dichroic mirrors 411, 412, and 413 with quarter-wave plates are disposed between the polarizing beam splitter 404 and the light emitting diodes 401, 402, and 403. The difference from the first embodiment is that a plate-shaped polarizing beam splitter 414 is used in order to realize lighter weight and lower cost, and that a dichroic mirror and a quarter wavelength plate are integrated. It is. As the flat polarizing beam splitter, for example, a wire grid type polarizing beam splitter manufactured by Moxtec, Inc., USA is commercially available. The dichroic mirrors 411, 412, and 413 with a quarter-wave plate are obtained by vapor-depositing a dielectric multilayer film on the front side of a glass substrate, and a film-type quarter-wave plate on the back side where no deposited film is formed. Were placed so that the side on which the dielectric multilayer film was formed faced the light emitting diode side. The paths through which the light beams emitted from the R, G, and B light emitting diodes 401, 402, and 403 are emitted from the light source device 400 are the same as those described above with reference to FIG.

  Since the flat polarizing beam splitter is much lighter than the glass polarizing beam splitter, it greatly contributes to the weight reduction of the light source device 400.

  In the above description, the light emitting diode is an example of a light emitting diode integrated with a shell-type lens. However, a lens system may be added to improve the parallelism of a light beam emitted from the light emitting diode. In this case, it is preferable to provide a lens system between the light emitting diode and the dichroic mirror.

(Second Embodiment)
FIG. 5 is a schematic configuration diagram showing an example of a projection display device including the light source device according to the first embodiment of the present invention, which is the second embodiment of the present invention. The light beam emitted from the light source device 100 of the present invention described in the first embodiment illuminates the DMD 502 that is a display device via the prism 503. The light beam modulated by the DMD 502 is enlarged and projected by the projection lens 504. Here, from the light source device 100, for example, by controlling the lighting of the light emitting diodes 101, 102, and 103 so as to repeat the color light of R → G → B, a color image of a color sequential display method can be obtained. In addition to the repetition of color light such as R → G → B, a time for turning on the light emitting diodes of all colors and the lighting control of repetition of R → G → B → W (white) will result in a brighter projected image. It can also be obtained.

It is a schematic plan view which shows the structure of the light source device of the 1st Embodiment of this invention. It is typical explanatory drawing explaining operation | movement of the light source device of this invention. (A) is a schematic diagram which shows the optical path of the light beam inject | emitted from the light emitting diode (R). (B) is a schematic diagram which shows the optical path of the light beam inject | emitted from the light emitting diode (G). (C) is a schematic diagram which shows the optical path of the light beam inject | emitted from the light emitting diode (B). It is explanatory drawing which shows the characteristic of the dichroic mirror of the light source device of this invention. It is a typical top view which shows the structure of the modification of 1st Embodiment of the light source device of this invention. It is a typical block diagram which shows an example of the projection type display apparatus provided with the light source device of the 1st Embodiment of this invention which is the 2nd Embodiment of this invention.

Explanation of symbols

100, 400 Light source device 101, 401 Light emitting diode (R)
102, 402 Light emitting diode (G)
103, 403 Light-emitting diode (B)
104, 105, 106 Dichroic mirror 107, 108, 109 1/4 wavelength plate 110, 414 Polarization beam splitter 111 Polarization separation surface 301 Characteristic (R)
302 Characteristics (G)
303 Characteristics (B)
401, 402, 403 Dichroic mirror with quarter wave plate 500 Projection display device 502 DMD
503 Prism 504 Projection lens (211) to (217), (221) to (226), (231) to (236)

Claims (8)

A first light emitting diode that emits first color light, a second light emitting diode that emits second color light, a third light emitting diode that emits third color light, and the first to third color lights are combined. In a light source device equipped with a color synthesis optical system for
The color synthesizing optical system includes three types of dichroic mirrors having different wavelength selectivity, each having a quarter wavelength plate , and a polarization beam splitter, and the quarter wavelength plate is close to the polarization beam splitter. Is located on the side ,
Three types of the dichroic mirrors are arranged in a U shape at a position forming an angle of 45 degrees with respect to the polarization separation surface of the polarization beam splitter,
The first to third light emitting diodes are provided in proximity to each of the dichroic mirrors, and light beams from the first to third light emitting diodes are combined into one optical path and emitted. A light source device.   The light source device according to claim 1, wherein the first color light is R color (red), the second color light is G color (green), and the third color light is B color (blue).   The characteristic of the dichroic mirror disposed between the first light emitting diode and the polarization beam splitter is that the color light of the first light emitting diode is transmitted and the color light of the second and third light emitting diodes is transmitted. The characteristic of the dichroic mirror having a characteristic to reflect and disposed between the second light emitting diode and the polarization beam splitter is such that the colored light of the second light emitting diode is transmitted, and the first and the first And the dichroic mirror disposed between the third light emitting diode and the polarization beam splitter transmits the color light of the third light emitting diode. The light source device according to claim 1, wherein the light source device has a characteristic of reflecting color light of the first and second light emitting diodes. The polarization beam splitter, the hypotenuse which is the polarized beam splitter dielectric multilayer film is combined span the rectangular prism comprising two optical glass formed structure according to any one of claims 1 to 3 Light source device. The polarization beam splitter is a plate-shaped polarization beam splitter, the light source device according to any one of claims 1 to 3. Wherein the quarter-wave plate dichroic provided independently of the dichroic mirror, the light source device according to any one of claims 1 to 5. Wherein the said dichroic mirror and the quarter-wave plate are integrally formed, the light source device according to any one of claims 1 to 5. A light source device according to any one of claims 1 to 7 , wherein the light beam from the light source device is irradiated onto a single DMD display panel, and an image modulated by the DMD display panel is projected by a projection lens. Projection-type display device that displays an enlarged image.

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