JP2007316295A - Lighting system and projector using lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and highly efficient lighting system obtaining uniformity of sufficient illumination light even when the length of a rod integrator is comparatively short, and to provide a projector using it. <P>SOLUTION: A light flux division element 50 is arranged just before an incident end face of the rod integrator 29. A light flux is divided by the light flux division element 50. Therefore, a plurality of the light fluxes controlled in arbitrary intensity near to uniformity are made incident on the rod integrator 29 by changing the characteristics of a half-mirror composing the light flux division element. Since the light fluxes from them are equivalent to be made incident as a plurality of light sources exist in the rod integrator 29, uniform illumination light can be obtained even with the comparatively short rod integrator 29 without positively using inner face reflection of the rod integrator 29. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illuminating device and a projector using the illuminating device, and more particularly to an illuminating device having a beam splitting unit and a projector using the illuminating device.

As a conventional projector, a light beam from a light source is incident on the incident end face of a prismatic rod integrator. A projector having an optical system is known (see Patent Document 1, Patent Document 2, and Non-Patent Document 1).
JP 2000-112031 A JP 2004-184611 A "A Handheld-Mini-Projector UsingLED Light Sources" SID 05 DIGEST pp 1706-1709

  In the projector as described above, since the configuration of the optical system is simple and the number of parts is small, there is a possibility that a small and low-cost projector can be provided. In particular, if a solid-state light source is used as the light source, the power consumption is reduced, and a hand-held projector that can be driven by a battery is no dream. By the way, in the projector having such a configuration, it is known that the longer the length of the rod integrator, the higher the luminance uniformity of the light beam that irradiates the liquid crystal panel. This is because the light flux from the light source incident on the rod integrator becomes a light flux with uniform illuminance distribution or luminance distribution due to repeated internal reflection in the rod integrator. It is. However, the lengthening of the rod integrator is not preferable in terms of downsizing because the size of the lighting device is increased.

  An object of the present invention is to provide a small and highly efficient illumination device capable of obtaining sufficient illumination light uniformity even if the length of the rod integrator is relatively short, and a projector using the same.

The lighting device of the present invention includes:
An illumination device having a rod integrator that irradiates an image display with light from a light source, characterized in that it has a light beam splitting unit that is arranged on the incident side of the rod integrator and splits light from the light source into a plurality of light beams. .

  The beam splitting means may have a half mirror as a component, or may have a plurality of half mirrors and a total reflection mirror. The transmission and reflection ratio of the half mirror may be set so that the incident light to the rod integrator is uniform, and the half mirror may be a dielectric multilayer film.

  In the light beam splitting means, the components are arranged in an aligned state in a direction perpendicular to the optical axis of the input light beam, and the half mirror has an angle of approximately 45 degrees with respect to the optical axis of the input light beam, and You may arrange | position symmetrically with respect to the centerline of this light beam splitting means. Further, the half mirror may divide the light beam from the light source in the horizontal direction or the vertical direction of the display surface of the image display. The light source may be an LED or a semiconductor laser.

  A projector according to the present invention includes the above-described illumination device, an image display, and a projection optical system. The image display may be a liquid crystal panel.

  In an illuminating device that irradiates the image display device with a light beam that is incident on the rod integrator from the incident end surface of the rod integrator and that is converted into a rectangular shape by the rod integrator, a light beam splitting element is placed immediately before the incident end surface of the rod integrator By making multiple light beams, which are split and adjusted by the light beam splitting element, enter the rod integrator, the brightness distribution is made uniform by the light beam splitting element, so the length of the rod integrator can be shortened and the projector can be made compact. Can be achieved.

  As described above, according to the illumination device of the present invention and the projector using the illumination device, the light beam splitting element is disposed immediately before the incident end surface of the rod integrator, and a plurality of light beams split and adjusted by the light beam splitting element are Since it is made incident on the integrator, the rod integrator is equivalent to the presence of a plurality of light sources, and the light beams from them are incident, so without actively using the internal reflection of the rod integrator, that is, Even with a rod integrator having a relatively short length, there is an effect that uniform illumination light can be obtained. The reason is that by changing the characteristics of the half mirror that constitutes the light beam splitting element, it is possible to control the split light flux by the light beam splitting element to an arbitrary intensity, so that the luminance balance of the light flux emitted from the rod integrator is adjusted. This is because it can be made uniform. And in the projector using such an illuminating device, since the length of a rod integrator is comparatively short, there exists an effect that a very small projector can be provided.

  Small size that can obtain uniform illumination light without increasing the length of the rod integrator by splitting the light flux from the light source just before the rod integrator and controlling the intensity of each to make it enter the rod integrator It is a feature of the present invention that a lighting device and a projector using the lighting device can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an optical system of a projector provided with the illumination device according to the first embodiment of the present invention. The optical system 10 of the projector 1 includes an illumination device 20, an image display unit 30, and a projection optical system 40. The illuminating device 20 includes a light source 21, three sets of condensing lenses 22, 23, and 24 arranged in series, a light beam splitting element 50 that is a feature of the present invention, and a rod integrator 29, and an image display unit. The 30 single image displays 31 are irradiated with RGB light from the light source 21 in a time-sharing manner. Here, the image display 31 is a single-plate type liquid crystal display, but is not limited to this, and can be applied to a grid-like reflection type image forming element (DMD).

  In this embodiment, a light emitting diode is used as the light source 21 in order to reduce the size of the lighting device 20. As the light source 21, it is preferable to use a light emitting diode that emits as much light as possible. For example, the Ostar series of OSRAM Opto Semiconductor, Germany can be used. This light emitting diode is configured by adjoining four light emitting chips each having a size of about 1 mm × 1 mm as a size of the light emitting element, and has a size of about 2.1 mm × 2.1 mm as a whole. All four light emitting elements have the same color, and of the four, there are one each of red and blue light emitting elements, the remaining two are green, and red blue green light emitting elements are in one package. . In the example of FIG. 1, the latter, that is, red, blue and green, is used in one package. However, the light source is not limited to the light emitting diode, and may be a semiconductor light emitting element. Although the present invention can be applied to a high-pressure discharge lamp, it is not so desirable from the viewpoint of miniaturization of the lighting device that is the object of the present invention.

  Since the light beam emitted from the light emitting diode is generally divergent light, a condensing lens group is used to efficiently use the light beam in the optical system 10, that is, to collect light with high efficiency. The condensing lenses 22, 23, and 24 arranged on the light source 11 and the condensing lenses 22, 23, and 24 constitute an RGB light source unit 121. From the side closest to the light source 21, a glass hemispherical condensing lens 22, a meniscus condensing lens 23 made of glass, and a condensing lens 24 composed of a glass convex lens are formed.

  Note that the configuration of these lenses is not necessarily limited to this combination, and can be changed as appropriate. For example, as an application example, if red, blue, and green light emitting diodes are arranged so that their optical paths overlap, the configuration shown in FIG. 2 is obtained. FIG. 2 is a schematic configuration diagram of an application example of an optical system of a projector provided with the illumination device of FIG.

  In this example, a red light source unit 122R composed of a red light emitting diode and a condensing lens group, a green light source unit 122G composed of a green light emitting diode and a condensing lens group, a blue light emitting diode and a concentrator. The light beam emitted from the blue light source unit 122 </ b> B composed of the optical lens group is synthesized by the cross dichroic mirror 25, which is a well-known technique, and emitted to the rod integrator 29 via the light beam splitting element 50 by the lens 26. Yes.

  Next, the configuration of the light beam splitting element 50 will be briefly described. The light beam splitting element 50 has a function of splitting an incident light beam into a plurality of light beams. In the present embodiment, a plurality of prisms are bonded together and a half mirror is vapor-deposited on the bonded surface. In addition, the definition of the half mirror described in the present application indicates not only a general characteristic of separating a light beam into 1: 1 but also a characteristic having a characteristic of dividing at an arbitrary ratio. The design and manufacture of such transmissive and reflective mirrors is well known in the art.

  A specific configuration example of the light beam splitting element 50 is shown in FIG. FIG. 3 is a schematic perspective view showing a configuration example of the light beam splitting element according to the first embodiment. In this configuration example, the light beam splitting element 51 includes a total of five prisms 501 each having an apex angle of 45 ° with respect to the center line, prisms 502 and 503 having a parallelogram in section, and two prisms 504 and 505. It consists of a prism. Here, half mirrors are formed on the two inclined surfaces 506 of the prism 501, and reflecting mirrors are formed on the inclined surfaces 507 of the prisms 504 and 505. Furthermore, the slopes of the five prisms 501 to 505 are joined with an optical adhesive. For example, a dielectric multilayer film is used as the half mirror, and the transmission and reflection ratios can be arbitrarily set by design. Such a dielectric multilayer film can be obtained by a known technique.

  Although this configuration example includes a total of five prisms, the prisms 504 and 505 can be reduced as shown in the plan view of FIG. FIG. 4 is a schematic plan view showing an application example of the light beam splitter according to the first embodiment. In the light beam splitting element 52, the prism slope 507 of the prisms 502 and 503 is 45 degrees with respect to the incident light, and the light reflected from the half mirror of the prism slope 506 of the prism 501 is formed here. This is because it is possible to totally reflect. In this way, the number of parts can be reduced. Although not shown, the light beam splitting element 50 may be formed of a plate-like half mirror or reflection mirror instead of a prism.

  A rod integrator 29 is provided after the light beam splitting element 50. The rod integrator 29 is made of solid optical glass, and its six surfaces are optically polished and used. As a material, BK7 can be used as an inexpensive material. For example, a size of 12 mm × 16 mm × 30 mm (length × width × length) is used for a 0.7-type liquid crystal panel. Instead of the rod integrator, a light tunnel composed of a plate-like reflecting mirror may be used. The light beam splitting element 50 and the rod integrator 29 may be arranged with a minute air gap, or the rod integrator 29 and the light beam splitting element 50 may be integrated by bonding.

  As the image display 31, a liquid crystal panel is usually used. As the liquid crystal panel, a liquid crystal panel having a high liquid crystal response speed is preferable so that single plate driving is possible. As the projection lens of the projection optical system 40, for example, a 0.7 type liquid crystal panel having a focal length of 25 mm and an F number of 1.4 is used.

  Next, the operation of the illumination device in the optical system of the projector according to the embodiment of the present invention will be described. FIG. 5 is a schematic diagram showing the flow of the light beam projected from the light source of the optical system having the illumination device according to the embodiment of the present invention. In FIG. 5, a light beam from a light-emitting diode that is a light source 21 enters a light beam splitting element 50 by the lens action of the condenser lenses 22, 23, and 24 and the lens 27. Then, the light is split into three uniform light beams by the light beam splitting element 50. The three light beams separated by the light beam splitting element 50 then enter the rod integrator 29. The light beam emitted from the rod integrator 29 illuminates the liquid crystal panel as the image display 31, and the image on the image display 31 is enlarged and projected onto a screen (not shown) by the projection optical system 40. A light path from a light emitting diode as the light source 21 can be indicated by a light beam 61 in the drawing.

  The operation of the light beam splitting element 50 will be described with reference to FIG. FIG. 6 is a schematic diagram showing details of the flow of the light beam incident on the light beam splitting element of FIG. The light beam 61 incident on the light beam splitting element 50 reaches the half mirrors 511 and 512 constituting the light beam splitting element 50. For example, the half mirrors 511 and 512 transmit about 40% of the incident light and pass through the light. 60% of light is reflected. The light transmitted through the half mirrors 511 and 512 travels straight and enters the rod integrator 29 (light flux 62). The light reflected from the half mirrors 511 and 512 has its path bent at a right angle, but is totally reflected by the parallelogram prism surfaces 508 and 509, changes its path to the rod integrator 29 side, and enters the rod integrator 29 ( Luminous flux 63, luminous flux 64). Looking at the light beam incident on the rod integrator 29, it can be considered that there are three light sources and light rays from these light sources are incident on the rod integrator 29.

  By the way, the optical action of the rod integrator 29 originally creates a large number of secondary light sources by internal reflection and superimposes them on the exit surface of the rod integrator 29 so that the superimposed uniform illumination information is displayed on the image display. It is used for 31 lighting. As a result, uniform brightness or illuminance distribution on the projection screen is achieved. When this is compared with this embodiment, although there is a difference that there are three secondary light sources in this embodiment, illumination light with uniform luminance is formed on the exit surface of the rod integrator 29. There is something in common. The difference is that the secondary light source is positively prepared when the rod integrator is incident without relying on internal reflection. Therefore, the rod integrator 29 according to the present application may be a prismatic light guide member having a very short length compared to the rod integrator of the prior art.

  Next, a modification of the present embodiment will be described. Various modifications can be made to the first embodiment described above. That is, in the first embodiment, three secondary light sources are created, but it is easy to create more secondary light sources.

  FIG. 7 is a schematic perspective view showing a configuration example of a light beam splitting element according to the second embodiment of the present invention. For example, if a light beam splitting element 53 as shown in FIG. 7 is prepared, seven secondary light sources can be obtained. That is, the light beam splitting element 53 includes six parallelogram prisms 602 to 607 and a triangular prism 601, and a half mirror is formed on each joint surface. The transmission / reflection characteristics of the half mirror are arbitrarily set so that the light emitted from the light beam splitting element 53 is uniform. Further, the two prisms 606 and 607 at both ends are provided with total reflection surfaces 608. Such a configuration is the same as the provision of seven secondary light sources more than twice as compared with the first embodiment, and further uniformization is possible.

  FIG. 8 is a schematic top view showing the configuration and the optical path of the light beam splitting element of the illumination apparatus according to the third embodiment of the present invention. Instead of creating a secondary light source one-dimensionally as in the first and second embodiments, it is also possible to split a light beam two-dimensionally as in the third embodiment. The third embodiment includes a first light beam splitting element 54 in which prisms are arranged in a direction perpendicular to the paper surface, and a second light beam splitting element 55 in which prisms are arranged in a horizontal direction on the paper surface. Each of the light beam splitting elements splits the light beam into three so that it can be divided into nine in total. With such a configuration, even if the length of the rod integrator 29 is short, an even higher projected screen luminance distribution Can be made uniform. FIG. 9 is a schematic side view showing the configuration and the optical path of the light beam splitting element of the illumination apparatus according to the third embodiment of the present invention, and the optical path diagram shown in FIG.

It is a typical block diagram of the optical system of the projector provided with the illuminating device of the 1st Embodiment of this invention. It is a typical block diagram of the application example of the optical system of the projector provided with the illuminating device of FIG. It is a typical see-through | perspective perspective view which shows the structural example of the light beam splitting element of 1st Embodiment. It is a schematic plan view which shows the application example of the light beam splitting element of 1st Embodiment. It is a schematic diagram which shows the flow of the light beam projected from the light source of the optical system which has the illuminating device of embodiment of this invention. It is a schematic diagram which shows the detail of the flow of the light beam which injects into the light beam splitting element of FIG. It is a typical see-through | perspective view which shows the structural example of the light beam splitting element of the 2nd Embodiment of this invention. It is a typical top view which shows the structure and optical path of the light beam splitting element of the illuminating device of the 3rd Embodiment of this invention. It is a typical side view which shows the structure and optical path of the light beam splitting element of the illuminating device of the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector 10 Optical system 20 Illuminating device 21 Light source 22, 23, 24, 27 Condensing lens 25 Cross dichroic mirror 26 Rod integrator 30 Image display part 31 Image display 40 Projection optical system 50, 51, 52, 53 Light beam splitting element 54 First light beam splitting element 55 Second light beam splitting element 61, 62, 63, 64 Light beam 121 RGB light source unit 122R Red light source unit 122G Green light source unit 122B Blue light source unit 501, 502, 503, 504, 505, 602, 603 , 604, 605, 606, 607 Prism 506, 507 Inclined surface of prism 508, 509 Prism surface 511, 512 Half mirror 601 Triangular prism 608 Total reflection surface

Claims (10)

In an illumination device having a rod integrator that irradiates an image display with light from a light source,
An illuminating device, comprising: a light beam splitting unit that is disposed on an incident side of the rod integrator and splits light from the light source into a plurality of light beams.   The lighting device according to claim 1, wherein the light beam splitting unit includes a half mirror as a component.   The illumination device according to claim 1, wherein the light beam splitting unit includes a plurality of half mirrors and a total reflection mirror as constituent elements.   4. The illumination device according to claim 2, wherein a transmission ratio and a reflection ratio of the half mirror are set so that incident light to the rod integrator is uniform. 5.   The lighting device according to any one of claims 2 to 4, wherein the half mirror is made of a dielectric multilayer film.   In the light beam splitting means, the components are arranged in an aligned state in a direction perpendicular to the optical axis of the input light beam, and the half mirror has an angle of about 45 degrees with respect to the optical axis of the input light beam. The lighting device according to any one of claims 1 to 5, wherein the illumination device is arranged symmetrically with respect to the center line of the light beam dividing means.   The illumination device according to any one of claims 1 to 6, wherein the half mirror divides a light beam from a light source in a horizontal direction or a vertical direction of a display surface of the image display.   The lighting device according to any one of claims 1 to 7, wherein the light source is an LED or a semiconductor laser.   A projector comprising the illumination device according to claim 1, an image display, and a projection optical system.   The projector according to claim 9, wherein the image display is a liquid crystal panel.

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