JP2011113818A - Lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device improved in light use efficiency, related to the lighting device being, in particular, a light source of a projetion-type display device. <P>SOLUTION: Light emitted from the light source 10 is condensed by a cylindrical lens 13. The cylindrical lens 13 refracts a light distribution at a large angle emitted from the light source 10 to narrow the light distribution angle. The light condensed by the cylindrical lens 13 advances to a lamp reflector 14. A cross-sectional shape of the lamp reflector 14 is aspheric on its incidence and emission planes and linear on its reflecting surface. At the incidence surface 14a of the lamp reflector 14, the light is further refracted to narrow the light distribution angle. The light advanced to the reflecting surface 14b is totally reflected and then refracted at the emission surface 14c, enters a cone lens 15, and becomes substantially parallel with an optical axis of the lighting device to enter an incidence side fly-eye lens 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an illumination device, and more particularly to an illumination device that is a light source unit of a projection display device.

  As an illumination device for a projection display device, an illumination device as shown in FIG. 7 as a top view of an optical cross-sectional view has been conventionally used. In FIG. 7, 1 is a lamp bulb. Reference numeral 2 denotes a lamp reflector whose reflecting surface has a parabolic shape. Reference numeral 3 denotes an incident-side fly-eye lens, and reference numeral 4 denotes an exit-side fly-eye lens. Reference numeral 5 denotes a PBS (Polarized Beam Splitter). Reference numeral 6 denotes a first illumination lens, and reference numeral 7 denotes a second illumination lens. Reference numeral 8 denotes an incident polarizing plate, 9 denotes an LCD (Liquid Crystal Display), and 10 denotes a light source unit. Z represents the illumination system optical axis.

  The light emitted from the light source unit 10 is reflected by the lamp reflector 2 and enters the incident-side fly-eye lens 3 as light substantially parallel to the illumination system optical axis Z. The incident side fly-eye lens 3 collects the incident light on the emission side fly-eye lens 4 and enters the PBS 5. PS separation of light is performed in PBS5. Thereafter, the light travels to the first illumination lens 6 and the second illumination lens 7 and is irradiated onto the LCD.

  FIG. 8A is an enlarged view of the broken line portion of FIG. 7 and shows the light path when it is assumed that the light source unit 10 is an ideal point light source. Although not shown, the light source unit 10 includes an electrode in the center of the glass sphere, and emits light from between the electrodes. Generally, the center (arc center) between the two electrodes having the highest light emission luminance is configured to coincide with the paraboloid focus. The light source of the light source unit 10 is preferably an ideal point light source.

  However, in practice, the distance between the electrodes (arc length) is finite, and the light source unit 10 is widened. Therefore, when the light emitted around the arc center instead of the arc center is reflected by the lamp reflector 2, the ray angle of the emitted light becomes large as shown in FIG. It is known to contain a lot of light. A1 to A3 indicate optical paths of light emitted from the light source unit 10, and not only light emitted from the arc center but also light paths of light emitted from the periphery of the arc center. It can be seen that the light beam angle at the point 3 is wide and includes light that is not parallel to the illumination system optical axis Z.

  This means that in the above-described parallel illumination type illumination device, the degree of PS separation in the PBS of the light that has passed through the exit-side fly-eye lens is deteriorated, and consequently the illuminance of the screen is reduced.

  FIG. 9 shows a condensing illumination type illumination device using a rod lens. In FIG. 9, 1 is a lamp bulb, 12 is a lamp reflector, and the reflecting surface has a spheroidal shape. Reference numeral 10 denotes a light source unit, and B1 to B3 denote light emitted from the light source unit 10, respectively. 11 is a rod lens. Also in this illuminating device, when the light ray angle as described above becomes large, the light ray angle at the incident surface of the rod lens 11 becomes large, and light leakage occurs at the incident surface, resulting in loss. As a result, the screen illuminance decreases and the contrast deteriorates.

  In order to solve the above-described problems, Patent Document 1 is disclosed as a conventional technique related to a parallel illumination method. Patent Document 1 will be described with reference to FIG. Reference numeral 22 denotes an optical axis, and 21 denotes an irradiated surface. A reflecting mirror 170 has a parabolic axis 173 inclined with respect to the optical axis and rotated around the optical axis. By adopting such a shape, the rim diameter of the reflecting mirror can be reduced, so that the light collection efficiency on the irradiated surface 21 is improved. In addition, a so-called hollow-out phenomenon in which only the central portion of the irradiated surface 21 becomes a shadow image in the shadow of the light source lamp is reduced. Reference numeral 171 denotes a conical lens, and 172 denotes a focal point of the reflecting mirror. As the light source, a light source lamp having an excellent point light source property such as a xenon lamp is used.

  When the light beam exiting the focal point 172 is reflected by the reflecting mirror 170 above the optical axis 22, it becomes a light beam parallel to the parabolic axis 173. Similarly, the light beam reflected by the reflecting mirror 170 below the optical axis 22 also becomes a parallel light beam, and travels in the direction of collecting on the optical axis 22. The light beam that has passed through the conical lens 171 enters the irradiated surface 21 as a light beam parallel to the optical axis 22. With the above configuration, it is possible to produce a parallel and uniform light beam.

  Moreover, patent document 2 is disclosed as a prior art regarding a condensing illumination system. Patent Document 2 will be described with reference to FIG. Reference numeral 22 denotes an optical axis. Reference numeral 100 denotes a lamp, and 100a denotes a light emitting unit. Reference numeral 100b denotes a deformed lamp reflector, and the aspherical reflecting surface has a shape close to a spheroid obtained by rotating a plane curve represented by a polynomial around the optical axis. By setting it as such a shape, the divergence angle of the light beam radiate | emitted from an aspherical reflective surface is made smaller. The lamp front lens 100c is an aspheric lens that is symmetrical with respect to the optical axis. Reference numeral 300 denotes a rod integrator, and 300a, 300b, and 300c denote an entrance surface, a side surface, and an exit surface, respectively.

  The light emitted from the light emitting unit 100a is reflected by the aspherical reflecting surface of the deformed lamp reflector 100b, collected by the lamp front lens 100c, and the emitted light is incident on the incident surface 300a of the rod integrator 300. With the above configuration, it is possible to reduce the loss of light at the entrance surface of the rod integrator.

JP-A-5-323258 JP 2002-298625 A

  If the technique described in Patent Document 1 is used, a parallel and uniform light beam can be obtained, so that the light beam angle of light incident on the incident-side fly-eye lens can be reduced. Even in the technique described in Patent Document 2, the divergence angle of the light beam emitted from the lamp reflector can be suppressed, so that the loss of light on the incident surface of the rod lens can be reduced.

  However, using any of the techniques described in any of the above-mentioned patent documents, there remains a problem that the light beam angle is widened due to the light emitted around the arc center, which means that the illumination efficiency and the separation in PS separation in PBS This causes a decrease in the degree of brightness, which in turn causes a decrease in illuminance on the screen and a deterioration in contrast.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to realize a projection display device that can suppress the ray angle of light reflected by a lamp reflector and has high light utilization efficiency. .

  An illuminating device according to the present invention includes a light source unit, a cylindrical lens that collects light emitted from the light source unit, an incident surface on which light emitted from the cylindrical lens is collected, and an incident surface A lamp reflector having a reflecting surface for reflecting light and an exit surface for collecting the reflected light and having a rotationally symmetric shape about the illumination system optical axis; and the lamp disposed in front of the lamp reflector. It is characterized by comprising a rotationally symmetric lens that changes the traveling direction of light reflected by the reflector so as to follow the illumination system optical axis.

  In the illuminating device according to the present invention, even if the light emitted around the arc center instead of the arc center is reflected by the lamp reflector, the light beam angle of the reflected light can be reduced. Parallel light can be obtained. In the projection type display device using the present invention, it is possible to improve the illumination efficiency and the degree of separation in PS separation with PBS, and thus improve the contrast of projected images and the illuminance on the screen.

The figure which showed schematic structure of the light source unit regarding the 1st Example of this invention with the cross-sectional shape. The figure which showed the upper half of schematic structure of the light source unit regarding the 1st Example of this invention by sectional shape. The figure which compared the incident angle distribution in the entrance plane of an incident side fly eye lens with the conventional system. The figure which showed schematic structure of the light source unit regarding the 2nd Example of this invention with the cross-sectional shape. The figure which compared the incident angle distribution in the entrance plane of a rod lens with the conventional system. The figure which showed schematic structure of the light source unit regarding the 3rd Example of this invention with the cross-sectional shape. The figure which showed the cross-sectional shape of schematic structure of a projection type display apparatus. The figure which showed schematic structure of the light source unit of the projection display apparatus of the conventional parallel illumination system in the cross-sectional shape when it is assumed that a light source part is an ideal point light source. The figure which showed schematic structure of the light source unit of the projection type display apparatus of the conventional parallel illumination system by sectional shape. The figure which showed schematic structure of the light source unit of the projection type display apparatus of the conventional condensing illumination system regarding the 2nd Example of this invention with the cross-sectional shape. The figure which showed the structure of the light source device used for the conventional projection type display apparatus. The figure which showed the structure of the conventional condensing optical system.

  Several embodiments of the invention are described below. In addition, this invention is not limited to a following example.

  A first embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is an optical sectional view of the first embodiment of the present invention, particularly focusing on the light source unit. Reference numeral 1 denotes a lamp bulb. A light source unit 10 includes an electrode in a glass sphere (not shown), and emits light between the electrodes. The distance between the electrodes (hereinafter referred to as arc length) is approximately 1 mm. The light source unit 10 includes an arc lamp such as a metal halide lamp or a high-pressure mercury lamp. The center between the two electrodes having the highest emission luminance (hereinafter referred to as arc center) is configured to coincide with the focal point of the paraboloid. Z is the illumination system optical axis.

  Reference numeral 13 denotes a cylindrical lens, and its shape needs to be designed so as to optimize lens aberration. That is, as shown in FIG. 2 (only the upper half of FIG. 1 is shown), the design is optimized so that the virtual image 20 of the light source unit 10 by the cylindrical lens 13 does not spread. In the present embodiment, the incident side (the light source unit 10 side) of the lens cross-sectional shape has a single R shape, and the emission side (the lamp reflector 14 side) has an elliptical shape to reduce aberrations. Note that R represents the radius of a circle, and a single R shape means a single arc curve in which the center position of the radius of curvature is drawn at one point.

  Reference numeral 14 denotes a lamp reflector, and the shape of the incident surface 14a is aspherical in consideration of illumination system aberration. As an aspherical shape, an elliptical shape is easy to design and is highly effective. Although not shown, the optical axis of the aspheric surface of the incident surface is substantially coincident with the light beam emitted from the light source unit 10 perpendicular to the illumination system optical axis Z. The shape of the incident surface needs to be designed in consideration of the balance between the angle of the reflecting mirror constituting the reflecting surface 14b and the curved shape of the exit surface.

  The reflecting surface 14b of the lamp reflector 14 is a reflecting mirror having a linear cross section. This is because the conventional reflection mirror has an elliptical shape or a parabolic shape, but the illumination system aberration is reduced. Further, the reflecting surface 14b of the reflecting mirror needs to be vapor-deposited for totally reflecting visible light.

  The shape of the exit surface 14c is elliptical in consideration of design difficulty or effect, and is configured so that the optical axis of the light reflected by the reflecting mirror matches the aspherical optical axis of the exit surface. To do.

  A cone lens 15 has a lens shape rotationally symmetric with respect to the illumination system optical axis Z. The cross-sectional shape of the cone lens 15 is a linear shape for both the entrance surface 15a and the exit surface 15b, and the traveling direction of the light reflected by the reflecting mirror is changed to be parallel to the illumination system optical axis. Reference numeral 3 denotes an incident side fly-eye lens. With the light source unit 10 as the center, the cone lens 15 side is the front side, and the other side is the rear side.

  Next, with reference to FIG. 1, the optical path radiated | emitted from the light source part 10 of a present Example is demonstrated. The light emitted from the light source unit 10 is collected by the cylindrical lens 13. The purpose of arranging the cylindrical lens 13 is to narrow the light distribution angle by refracting the light distribution with a large angle emitted from the light source unit 10. The light A6 emitted to the rear side is changed to the front side, the light A5 emitted perpendicularly to the illumination optical axis Z goes straight, and the light A4 emitted to the front side is changed to the rear side.

  The light condensed by the cylindrical lens 13 travels to the lamp reflector 14. The light is further refracted by the incident surface 14a of the lamp reflector 14 to narrow the light distribution angle. Thereafter, the light is totally reflected by the reflecting surface 14 b of the lamp reflector 14, is refracted by the exit surface 14 c, and enters the incident surface 15 a of the cone lens 15 approximately perpendicularly. The light is refracted by the exit surface 15b and enters the incident-side fly-eye lens 3 so as to be substantially parallel to the illumination system optical axis.

  In the conventional illumination system shown in FIG. 8B, the light beam angles of the light A1 to A3 emitted from the light source unit 10 are larger than the light beam angles of the light beams A4 to A6 in FIG. It has become. FIG. 3 shows the incident angle light amount distribution in the incident side fly-eye lens in which the lamp angle distribution is the same and the incident angle distribution when the illumination range in the incident side fly-eye lens is the same is compared with the conventional method. . The arc length is approximately 1 mm. The incident angle is an angle inclined from the illumination system optical axis of the light incident on the incident side fly-eye lens. As can be seen from FIG. 3, it can be seen that the present invention increases the component having a smaller incident angle than the conventional example. That is, compared with the conventional example, the light incident on the incident side fly-eye lens is more parallel to the illumination system optical axis, which contributes to the improvement of the PS separation degree in PBS and thus the illuminance of the screen. I can do it.

  With the above configuration, the light emitted from the light source unit 10 is collected by the cylindrical lens 13 and is incident on the lamp reflector 14 so as to be totally reflected by the reflecting surface 14b, so that it is reflected by the reflecting surface 14b of the lamp reflector 14. The ray angle of the emitted light can be suppressed.

  A second embodiment of the present invention will be specifically described with reference to the drawings. FIG. 4 is an optical sectional view of the second embodiment of the present invention, particularly focusing on the light source unit. Reference numeral 1 denotes a lamp bulb, 10 denotes a light source section, 13 denotes a cylindrical lens, and 14 denotes a lamp reflector. Since these configurations are the same as those in the first embodiment described above, a description thereof will be omitted. Reference numeral 16 denotes a cone lens. In this embodiment, the cone lens 16 has an incident surface 16a having an aspherical elliptical shape and an exit surface 16b having a single R shape. The single R shape has already been described above.

Reference numeral 11 denotes a rod lens, which is a columnar glass, and has a structure in which light received at the incident surface is transmitted through the inside and emitted from the emission surface. Z is the illumination system optical axis. With the light source unit 10 as the center, the cone lens 16 side is the front side, and the other side is the rear side.
Next, the optical path of light emitted from the light source unit 10 of this embodiment will be described with reference to FIG. Since the optical path of the light until it enters the cone lens 16 is the same as that of the first embodiment described above, a description thereof will be omitted. The light emitted from the emission surface 14 c of the lamp reflector 14 proceeds to the cone lens 16. The light incident on the cone lens 16 is refracted by the exit surface 16 c and collected by the rod lens 11.

  In the conventional illumination system shown in FIG. 9, the light beam angles of the light beams B1 to B3 are larger than the light beam angles of the light beams B4 to B6 in FIG. 4 according to the present invention. Further, FIG. 5 shows the incident angle light amount distribution in the incident side rod lens in which the incident light distribution is the same when the lamp light distribution is the same and the illumination range on the rod lens incident surface is the same, compared with the conventional method. The arc length is approximately 1 mm. The incident angle is an angle at which light incident on the rod lens is inclined from the illumination system optical axis. As can be seen from FIG. 5, in the present invention, the angle component of the incident angle distribution near the illumination system optical axis is increased as compared with the conventional example. If this incident angle distribution has many angle components close to the optical axis of the illumination system, it contributes to improvement of optical performance such as contrast of projector performance, color purity, and projection lens resolution. In addition, since the loss of light quantity to the screen is reduced, the illuminance on the screen is also improved.

  With the above configuration, the light emitted from the light source unit 10 is collected by the cylindrical lens 13, and is incident on the lamp reflector 14 and totally reflected by the reflecting surface 14b. The angle can be suppressed. Thereby, the illumination size of the light on the rod lens incident surface can be reduced.

  A third embodiment of the present invention will be specifically described with reference to the drawings. FIG. 6 is an optical sectional view focusing on the light source unit of the third embodiment of the present invention. Reference numeral 1 denotes a lamp bulb, 10 denotes a light source unit, 13 denotes a first cylindrical lens, and 15 denotes a cone lens. Since these configurations are the same as those in the first embodiment described above, a description thereof is omitted. Reference numeral 17 denotes a second cylindrical lens. The incident surface 17a has a single R shape, and the output surface 17b has an aspherical elliptical shape. The single R shape has already been described above.

  Reference numeral 18 denotes a vapor deposition that totally reflects visible light by a reflection mirror. Reference numeral 19 denotes a cone lens. The incident surface 19a has a linear shape, and the output surface 19b has an aspherical elliptical shape. With the light source unit 10 as the center, the cone lens 15 side is the front side, and the other side is the rear side.

  Next, the optical path of light emitted from the light source unit 10 of this embodiment will be described with reference to FIG. Since the optical path of the light until it exits the cylindrical lens 13 is the same as that of the first embodiment described above, a description thereof will be omitted. The light emitted from the exit surface 13b of the first cylindrical lens is further refracted by the entrance surface 17a of the second cylindrical lens 17, and the light distribution angle is narrowed. Thereafter, the light is totally reflected by the reflection mirror 18 and enters the cone lens 19. The light that has traveled to the cone lens 19 is refracted by the exit surface 19 b and is incident on the cone lens 15.

  Incidence is approximately perpendicular to the incident surface 15 a of the cone lens 15. The light is refracted at the exit surface 15b and enters the fly-eye lens 3 so as to be approximately parallel to the illumination system optical axis.

  With the above configuration, the light emitted from the light source unit 10 is collected by the first cylindrical lens 13 and further incident on the second cylindrical lens 17 so as to be totally reflected by the reflection mirror 18. Thus, the light beam angle can be reduced. In addition, since the lamp reflector having the thick shape according to the first embodiment described above is divided into the second cylindrical lens 17, the reflection mirror 18, and the cone lens 19, the weight of the lighting device is reduced. Can also contribute.

  The present invention can improve the light use efficiency of the light emitted from the light source unit, and is thus useful for a projection display device.

DESCRIPTION OF SYMBOLS 1 Lamp bulb 2, 12, 14 Lamp reflector 3 Incident side fly eye lens 4 Outgoing side fly eye lens 5 PBS
6 First Illumination Lens 7 Second Illumination Lens 8 Incident Polarizing Plate 9 LCD
DESCRIPTION OF SYMBOLS 10 Light source part 11 Rod lens 13, 17 Cylindrical lens 15, 16, 19 Cone lens 18 Reflection mirror 20 Virtual image 21 Irradiated surface 22 Optical axis 100 Lamp 100a Light emission part 100b Deformation lamp reflector 100c Lamp front lens 170 Inclined parabolic mirror 171 Cone Lens 172 Focus 173 Parabolic axis 300 Rod integrator 300a Incident surface 300b Side surface 300c Outgoing surface Z Illumination system optical axis

Claims (2)

A light source unit;
A cylindrical lens that collects light emitted from the light source unit;
The illumination system has an incident surface on which light emitted from the cylindrical lens is collected, a reflection surface that reflects incident light, and an emission surface on which reflected light is collected. A lamp reflector having a rotationally symmetric shape as a center;
An illumination device comprising a rotationally symmetric lens disposed in front of the lamp reflector and changing a traveling direction of light reflected by the lamp reflector so as to be along the optical axis of the illumination system. A light source unit;
A first cylindrical lens for collecting the light emitted from the light source unit;
A second cylindrical lens for condensing light emitted from the first cylindrical lens;
A reflecting mirror that is rotationally symmetric about the optical axis of the illumination system and reflects light emitted from the second cylindrical lens;
A first rotationally symmetric lens disposed in front of the reflecting mirror for changing a traveling direction of light reflected by the reflecting mirror;
An illumination device comprising a second rotationally symmetric lens disposed in front of the first rotationally symmetric lens and changing a traveling direction of light emitted from the first rotationally symmetric lens so as to be along the illumination system optical axis.