JP2010008748A - Image projection device - Google Patents

Abstract

An illumination optical system 10 using a light pipe 1 is configured to increase the light intensity emitted from an emission end 4 and to be compact.
In an illumination optical system 10 including a light pipe 1 in which light incident from an incident end 3 is repeatedly reflected on the outer periphery 2 of the optical path and emitted from the exit end 4, a side incident end is provided on the side surface of the light pipe 1. 5, and an illumination optical system 10 provided with a reflecting surface 6 in which light incident from the side incident end 5 is reflected in the direction of the exit end 4 in the optical path of the light pipe 1.
[Selection] Figure 1

Description

  The present invention relates to an illumination device having a light pipe used for a projection device or the like. In particular, the present invention relates to an illuminating device that receives light from a plurality of incident ends corresponding to each of a plurality of light sources, and emits mixed light from one emission end.

  A projector that modulates light from a light source using a light modulation element such as a liquid crystal panel or a DMD (Digital Micromirror Device) and performs an enlarged projection with a projection lens has been put into practical use. This type of projection apparatus is convenient to carry and easily project a projected image on a wall or screen. In order to further improve this convenience, there has been a strong demand for reduction in size and weight in recent years. Along with this, light modulation elements, light sources, and illumination optical systems have been reduced in size and weight, and the magnification ratio of projected images has increased, and there is a demand for small and high-luminance illumination devices.

  In recent years, high-definition liquid crystal panels and DMDs have been developed, and a high-definition projection image can be enlarged and projected on a large screen. Therefore, there is a need for a lighting device that has a high uniformity in the luminance distribution of emitted light and that has a high luminance.

Patent Document 1 describes a light source device used in this type of projection apparatus. FIG. 8 is a schematic diagram of the light source device 50 described in FIG. The light source device 50 includes three light emitting elements 51R, 51G, and 51B installed on one side of the case body 58, reflecting surfaces 52R, 52G, and 52B that reflect light emitted from the light emitting elements 51R, 51G, and 51B, Mirrors 53 and 54 that reflect light from the light emitting elements 51R and 51B, a cross dichroic prism 55 that combines light emitted from the light emitting elements 51R, 51G, and 51B, and light emitted from the cross dichroic prism 55 A condenser lens 56 that collects light and a light tunnel 57 that introduces and transmits light collected from the condenser lens 56 are configured. With this configuration, the red light of the light emitting element 51R, the green light of the light emitting element 51G, and the blue light of the light emitting element 51B can be mixed, and mixed color light can be emitted from the emission end of the light tunnel 57. That's it.
JP 2006-10741 A

  However, in the light source device 50 disclosed in Patent Document 1, three light emitting elements are installed outside the light tunnel 57 (one side of the case body 58), two mirrors 53 and 54 are installed outside the light tunnel 57, and It is necessary to install a cross dichroic prism 55 for mixing the light from each light emitting element 51R, 51G, 51B. Therefore, the volume of the light source device 50 increases and the distance from each light emitting element 51R, 51G, 51B to the exit end of the light tunnel 57 also increases.

  In the present invention, the following means have been taken in order to solve the above problems.

In the invention according to claim 1, in the illumination optical system including the light pipe, the light incident from the incident end is repeatedly reflected and transmitted on the outer periphery of the optical path, and is emitted from the exit end.
A side incident end is provided on the side surface of the light pipe, and a reflection surface is provided in the optical path of the light pipe to reflect light incident from the side incident end in the direction of the emission end. It was set as the illumination optical system characterized by being.

  In the invention according to claim 2, a condensing means is provided at the side surface incident end, and the reflection surface is configured by a small reflection portion smaller than a cross section perpendicular to the light transmission direction of the optical path. 2. The illumination optical system according to claim 1, wherein the light collected by the light collecting unit is reflected by the small reflecting portion toward the emission end.

  In the invention according to claim 3, a condensing means is provided at the incident end, and a small transmission part smaller than a cross section perpendicular to the light transmission direction of the optical path is provided on the reflection surface. 3. The illumination optical system according to claim 1, wherein the light condensed by the condensing unit is transmitted through the small transmission part and emitted toward the emission end.

  In the invention according to claim 4, the light pipe is a solid type made of a solid member, and the optical path of the side surface incident end is constituted by an area smaller than the refractive index of the solid member. The illumination optical system according to any one of claims 1 to 3.

  According to a fifth aspect of the present invention, the diameter of the side incident end is smaller than the diameter of the incident end of the light pipe, and the small reflecting portion is provided in the vicinity of the side incident end. The illumination optical system according to any one of Items 2 to 4.

  According to a sixth aspect of the present invention, the illumination optical system according to any one of the first to fifth aspects is characterized in that the reflective surface is a concave reflective surface.

  The invention according to claim 7 is characterized in that a plurality of the side surface incident ends are provided on a side surface of the light pipe, and a plurality of the reflection surfaces are provided corresponding to each of the plurality of side surface incidence ends. The illumination optical system according to any one of claims 1 to 6.

  The illumination optical system according to claim 1 includes a light pipe that repeatedly reflects and transmits light incident from the incident end on the outer periphery of the optical path, and includes a side incident end on a side surface of the light pipe. In the optical path of the light pipe, an illumination optical system is provided in which a reflecting surface is provided that reflects light incident from the side incident end toward the exit end. With this configuration, light incident from a plurality of light sources can be combined and emitted from the emission end without installing a reflecting surface or a light mixing element outside the light pipe.

  Further, in the illumination optical system according to claim 2, a condensing means is provided at the side incident end, and the reflecting surface is constituted by a small reflecting portion smaller than a cross section perpendicular to the light transmission direction of the optical path, The light collected by the light means is reflected by the small reflecting portion toward the emission end. As a result, the loss of light incident from the side incident end can be reduced and reflected to the exit end side, and the loss of light incident from the incident end can be reduced by the small reflecting portion. In addition, light incident from both the incident end and the incident end can be efficiently synthesized.

  In the illumination optical system according to claim 3, a condensing unit is provided at the incident end, and a small transmission part smaller than a cross section perpendicular to the light transmission direction of the optical path is provided on the reflecting surface. The light collected by the light passes through the small transmission part and is reflected in the direction of the emission end. As a result, the loss of light incident from the incident end can be reduced and transmitted to the exit end side, and the light incident from the side incident end can be reflected by the reflection portion to the exit end side. Therefore, the light incident from both the side incident end and the incident end can be efficiently synthesized.

  In the illumination optical system according to the fourth aspect, the light pipe is a solid type using a solid member, and the optical path at the side surface incident end is configured by an area smaller than the refractive index than the solid member. As a result, the light incident from the incident end is totally reflected at the interface in contact with the side incident end region, so that loss due to leakage from the side incident end can be reduced.

  In the illumination optical system according to the fifth aspect, the diameter of the side incident end is smaller than the diameter of the incident end of the light pipe, and the small reflecting portion is provided in the vicinity of the side incident end. With this configuration, it is possible to reduce the loss of light leaking from the side wall incident end and improve the light utilization efficiency.

  In the illumination optical system according to a sixth aspect, the reflecting surface is a concave reflecting surface. Thereby, it becomes possible to adjust the reflection angle of the light incident from the side incident end on the outer periphery of the light pipe, and the emission angle of the light emitted from the emission end can be adjusted.

  In the illumination optical system according to the seventh aspect, a plurality of side surface incident ends are provided on the side surface of the light pipe, and a plurality of reflection surfaces are provided corresponding to the plurality of side surface incidence ends. Thereby, the emitted light with high light intensity can be obtained.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing a basic configuration of an illumination optical system according to the present invention. As shown in FIG. 1, the illumination optical system includes a light pipe 1. The light pipe 1 includes an outer periphery 2 of an optical path that reflects light, an incident end 3 that emits light into the optical path, an exit end 4 that emits light from the optical path, and a side incident that is installed on the side of the optical path and enters the light. It is comprised from the end 5 and the reflective surface 6 which is installed in the optical path and reflects the light incident from the side incident end 5 to the exit end 4 side.

  As a result, the light incident from the incident end 3 and the light incident from the side surface incident end 5 are combined, repeatedly reflected by the outer periphery of the optical path, and transmitted in the direction of the exit end 4. Since the light is repeatedly reflected on the outer periphery of the optical path, the light incident from the two incident ends is mixed inside the light pipe 1, and the emitted light with high light intensity can be obtained. As described above, since light is synthesized and mixed in the optical path of the light pipe 1, it is not necessary to install a reflecting surface or a prism for photosynthesis outside the light pipe 1, and illumination optics including the light pipe 1. The system can be made compact.

  As will be described in detail later, the light pipe 1 can be a hollow cylinder having a hollow cylindrical shape or a polygonal cylindrical body and having a reflective surface made of metal on the inner surface. Further, the light pipe 1 can be a solid cylinder or polygonal column whose interior is made of a transparent material, and can be a solid type utilizing total reflection on the outer peripheral surface. As the reflecting surface 6, a reflecting surface may be formed on a transparent member, or a prism or the like can be used. The reflective surface 6 may be a semi-transmissive type or a highly reflective surface made of a metal surface or the like. A plurality of side incident ends 5 can be formed on the side surface of the light pipe 1. Also in this case, a reflecting surface is provided corresponding to each side incident end. If a plurality of incident ends are configured in this manner, the light intensity of the emitted light can be further increased. Hereinafter, embodiments according to the present invention will be described in detail.

(Embodiment 1)
FIG. 2 is a schematic sectional view showing the illumination optical system 10 according to the first embodiment of the present invention. The same portions or portions having the same function are denoted by the same reference numerals. As shown in FIG. 2, the illumination optical system 10 includes a light pipe 1 made of a cylindrical body having a hollow inside. The light pipe 1 includes an incident end 3 for incident light, a side incident end 5 for incident light from the side surface of the light pipe 1, an exit end 4 for emitting light, and a side incident portion for guiding light to the side incident end 5. 17 and a small reflecting portion 18 that reflects the light incident from the side incident end 5 to the exit end 4 side. The illumination optical system 10 further includes a light source 12 and a reflection unit 13 provided at the incident end 3, and a light source 14, a reflection unit 15 and a condensing unit 16 provided at the side incident unit 17.

  The inner wall surface 11 of the light pipe 1 constitutes a reflecting surface and becomes the outer periphery of the optical path. When the light pipe 1 is made of, for example, metal, the inner wall surface 11 becomes a reflecting surface. When the light pipe 1 is made of glass, ceramics, or plastic material, a metal film is deposited on the inner wall surface 11 to form a reflecting surface. The light source 12 and the light source 14 use solid light emitting elements. The reflecting portion 13 and the reflecting portion 15 are mirror-finished on the inner surface and introduce light emitted from the light source 12 and the light source 14 into the light pipe 1. The small reflecting portion 18 installed in the optical path in the light pipe 1 has a shape smaller than the outer periphery of the optical path defined by the inner wall surface 11, that is, the cross section perpendicular to the light transmission direction of the optical path. The condensing means 16 installed inside the side incident part 17 condenses the light emitted from the light source 14 on the small reflection part 18. The small reflection portion 18 can be configured by forming a reflection surface at the center of the transparent substrate and inserting it obliquely into the light path of the light pipe 1. The reflected light is reflected toward the exit end 4 by this reflecting surface.

  The small reflection portion 18 has a shape smaller than a cross section perpendicular to the light transmission direction of the optical path. If the light from the light source 14 is condensed on the reflection surface 6 of the small small reflection portion 18, the loss of the light incident from the light source 14 can be reduced and guided in the direction of the emission end 4. In addition, since the external shape of the small reflection portion 18 is small, it is possible to reduce light loss due to light incident from the light source 12 being blocked by the small reflection portion 18. For example, if the outer shape of the small reflecting portion 18 in the direction of the optical axis 8 is d, the outer shape of the light path of the light pipe 1 is L, and d / L is approximately ½, the optical path is shielded by the small reflecting portion 18. The area ratio is approximately 25%. That is, the loss of light incident from the incident end 3 is approximately 25%. If d / L is approximately 1/4, the ratio of the shielded area is 6%, that is, the loss of light incident from the incident end 3 is approximately 6%. On the other hand, for example, when the light from the two light sources is synthesized using a dichroic prism as described in Patent Document 1, the loss of each light is approximately 50%. Therefore, it can be understood that the illumination optical system 10 according to the first embodiment greatly improves the light use efficiency from the light source.

  In addition, the angular distribution of the light incident from the incident end 3 and the angular distribution of the light reflected from the reflecting surface of the small reflecting portion 18 are made substantially equal. Thereby, the mixing ratio of the light of the light source 12 and the light source 14 emitted from the emission end 4 can be improved. The light traveling in the light pipe 1 is repeatedly reflected on the inner wall surface 11 serving as a reflection surface, but the reflection angle is maintained. That is, the angular distribution of the light incident from the incident end 3 is maintained and emitted from the outgoing end 4, and the angular distribution of the light reflected by the reflecting surface of the small reflecting portion 18 is also maintained and emitted from the outgoing end 4. By making the angular distribution of the light incident from the incident end 3 and the angular distribution of the light reflected from the reflecting surface 6 substantially equal, the mixing ratio of the light emitted from the emitting end 4 can be improved. For this reason, it is preferable that the small reflecting portion 18 is installed at the center of the optical path of the light pipe 1. Further, the reflection surface 6 of the small reflection portion 18 can be a recess, and the angle distribution of the reflected light can be adjusted by adjusting the curvature of the reflection surface.

  In addition, although the light sources 12 and 14 and the reflection parts 13 and 15 are provided in the incident end 3 and the side surface incident end 5, it may replace with this and may install LED (Light Emitting Diode). When the LED is installed, the illumination optical system 10 can be configured more compactly. Further, instead of the light sources 12 and 14 and the reflecting portions 13 and 15, light from a mercury lamp or a halogen lamp may be collected and incident from the incident end 3 and the side incident end 5.

(Embodiment 2)
FIG. 3 is a schematic cross-sectional view showing an illumination optical system 10 according to another embodiment 2 of the present invention. In the present embodiment, a solid light pipe 1 is used. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 2, the illumination optical system 10 includes a light pipe 1 made of a cylindrical body or a polygonal column. The light pipe 1 includes an incident end 3 for incident light, a side incident end 5 for incident light from the side surface of the light pipe 1, an exit end 4 for emitting light, and a side incident portion for guiding light to the side incident end 5. 17 and a small reflecting portion 18 that reflects the light incident from the side incident end 5 to the exit end 4 side. The illumination optical system 10 further includes a light source 12 and a reflection unit 13 provided at the incident end 3, and a light source 14, a reflection unit 15 and a condensing unit 16 provided at the side incident unit 17.

  Further, the light pipe 1 includes a solid portion 19 formed of transparent glass, transparent resin, or the like, and a protection portion 20 that covers and protects the outer periphery of the solid portion 19. The outer wall surface 21 of the solid part 19 constitutes a reflection surface that reflects light, and is the outer periphery of the optical path. Since the solid portion 19 has a refractive index of 1 or more, light incident on the outer wall surface at an incident angle greater than the critical angle is totally reflected on the surface. Further, if a reflective film is formed on the outer wall surface 21, a reflective surface that does not depend on the incident angle can be formed. The light source 12 and the light source 14 use solid light emitting elements. The reflecting portion 13 and the reflecting portion 15 are mirror-finished on the inner surface, and introduce light emitted from the light source 12 and the light source 14 into the light pipe 1.

  The small reflection portion 18 can be formed by cutting the solid portion 19 obliquely, forming a metal reflection film in a small region of the cut surface, and pasting the divided solid portion 19 with a transparent adhesive. The small reflection portion 18 has a shape smaller than the outer periphery of the optical path defined by the outer wall surface 21, that is, the cross section perpendicular to the light transmission direction of the optical path. The condensing means 16 installed inside the side incident part 17 condenses the light emitted from the light source 14 on the small reflection part 18. The condensed light is reflected in the direction of the emission end 4. Other configurations are the same as those of the first embodiment, and thus the description thereof is omitted.

  With this configuration, light incident from the incident end 3 onto the outer wall surface 21 at an inclination angle greater than the critical angle is totally reflected at the side incident end 5. Therefore, the light leaking from the side incident end 5 can be reduced, and the emission efficiency of the emitted light with respect to the incident light can be improved.

(Embodiment 3)
FIG. 4 is a schematic cross-sectional view showing an illumination optical system 10 according to another embodiment 3 of the present invention. In this Embodiment 3, the condensing means 16 is provided in the vicinity of the incident end 3 so that the incident light from the incident end 3 passes through the small transmission part 22 at the center of the reflecting surface 6 provided in the optical path. did. The same reference numerals are assigned to the same parts or parts having the same function.

  As shown in FIG. 4, the illumination optical system 10 includes a light pipe 1 made of a cylindrical body having a hollow inside. The light pipe 1 includes an incident end 3 for incident light, a side incident end 5 for incident light from the side surface of the light pipe 1, an exit end 4 for emitting light, and a side incident portion for guiding light to the side incident end 5. 17 and an internal reflection portion 23 that reflects the light incident from the side incident end 5 to the exit end 4 side. The illumination optical system 10 further includes a light source 12 and a reflection unit 13 provided at the incident end 3, a condensing means 16 provided near the incident end 3, and a light source 14 and a reflection unit 15 provided at the side incident unit 17. Contains.

  The inner wall surface 11 of the light pipe 1 constitutes a reflecting surface and becomes the outer periphery of the optical path. When the light pipe 1 is made of, for example, metal, the inner wall surface 11 becomes a reflecting surface. When the light pipe 1 is made of glass, ceramics, or plastic material, a metal film is deposited on the surface of the inner wall surface 11 to form a reflective surface. The light source 12 and the light source 14 use solid light emitting elements. The reflecting portion 13 and the reflecting portion 15 are mirror-finished on the inner surface and introduce light emitted from the light source 12 and the light source 14 into the light pipe 1. The internal reflection part 23 installed in the optical path in the light pipe 1 is installed so as to block the optical path of the light pipe 1, and a small transmission part 22 is formed in the center part. The surface of the inner reflection portion 23 is subjected to a mirror surface treatment, constitutes a reflection surface, and reflects the light incident from the side surface incident portion 17 toward the emission end 4. The small transmission part 22 formed in the central part transmits the light collected by the light collecting means 16 in the direction of the emission end 4.

  The aperture of the small transmission portion 22 is smaller than the outer shape of the optical path. If the light from the light source 12 is condensed on the small small transmission part 22, the loss of light from the light source 12 can be reduced and guided toward the emission end 4. Moreover, since the aperture of the small transmission part 22 is small, the loss which arises when the light from the light source 14 passes the small transmission part 22 can also be reduced. For example, if the aperture of the small transmission part 22 in the optical path direction of the side incident part 17 is h, the outer shape of the optical path of the side incident part 17 is P, and h / P is approximately ½, the incident from the side incident end 5 The ratio of the transmitted light through the small transmission part 22 is approximately 25%. That is, the loss of light incident from the side incident end 5 is approximately 25%. If h / P is approximately 1/4, the ratio of light passing through the small transmission part 22 is 6%, that is, the loss of light incident from the side incident end 5 is approximately 6%. On the other hand, for example, when the light from the two light sources is synthesized using a dichroic prism as described in Patent Document 1, the loss of each light is approximately 50%. Therefore, it can be understood that the illumination optical system 10 according to the first embodiment greatly improves the light use efficiency from the light source.

  Further, the angular distribution of the light passing through the small transmission part 22 and the angular distribution of the light reflected from the reflection surface of the inner reflection part 23 are made substantially equal. Thereby, the mixing ratio of the light of the light source 12 and the light source 14 emitted from the emission end 4 can be improved. The light traveling in the light pipe 1 is repeatedly reflected on the inner wall surface 11 serving as a reflection surface, but the reflection angle is maintained. That is, the angular distribution of the light incident from the incident end 3 is maintained and emitted from the outgoing end 4, and the angular distribution of the light reflected from the reflection surface of the inner reflection portion 23 is also maintained and emitted from the outgoing end 4. By making the angular distribution of the light incident from the incident end 3 substantially equal to the angular distribution of the light reflected from the reflection surface of the inner reflection portion 23, the mixing ratio of the light emitted from the emission end 4 can be improved. it can. For this reason, the small transmission part 22 is preferably installed at the center of the optical path of the light pipe 1. Further, the angle distribution of reflected light may be adjusted by adjusting the curvature of the reflection surface of the inner reflection portion 23 as a concave surface or a convex surface.

(Embodiment 4)
FIG. 5 is a schematic sectional view showing an illumination optical system 10 according to another embodiment 4 of the present invention. In the fourth embodiment, a side incident end 5 having a smaller diameter than the incident end 3 is formed on the side surface of the hollow light pipe 1, and light enters from the side incident end 5. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 5, the illumination optical system 10 includes a hollow light pipe 1 made of a cylindrical body. The light pipe 1 is installed in the vicinity of the incident end 3, the side incident end 5 having a diameter smaller than the diameter of the incident end 3, the exit end 4 for emitting light, and the side incident end 5. The small reflection part 18 which reflects the light which injects from the output end 4 direction is comprised. The illumination optical system 10 further includes a light source 12 and a reflection unit 13 provided at the incident end 3, a light source 14 installed near the outside of the side incident end 5, and light from the light source 14 to condense the side incident end. 5 is provided with a light condensing means 16 for condensing light.

  The small reflection portion 18 is provided in the vicinity of the side incident end 5. The light emitted from the light source 14 is collected by the light collecting means 16 and introduced into the light pipe 1 from the side incident end 5. Since the incident light is narrowed by the condensing means 16, the diameter of the side incident end 5 can be made sufficiently small. The small reflection portion 18 can be formed sufficiently small by being disposed close to the side surface incident end 5. Thereby, the loss of the light which the light which injected from the incident end 3 leaks out from the side surface incident end 5 can be reduced. Moreover, since the shape of the small reflection part 18 can be made small, the loss by light being shielded by the small reflection part 18 can also be reduced.

  The light pipe 1 may be a solid type instead of the hollow type. In this case, the small reflection portion 18 is obtained by cutting the solid portion obliquely, forming a metal reflection film in a small region near the side surface incident end 5 of the cut surface, and pasting the divided solid portion with a transparent adhesive. Can be configured. Other configurations are the same as those in the first or second embodiment, and thus the description thereof is omitted.

(Embodiment 5)
FIG. 6 is a schematic sectional view showing an illumination optical system 10 according to another embodiment 5 of the present invention. In the fifth embodiment, a plurality of incident ends are provided on the side surface of the light pipe 1. The same portions or portions having the same function are denoted by the same reference numerals.

  In FIG. 6, the illumination optical system 10 includes a light pipe 1. The light pipe 1 includes an incident end 3 for introducing light, a first side surface incident end 5a and a second side surface incident end 5b provided on a side surface of the light pipe 1, an output end 4 for emitting light, and a first side surface. A first side surface incident portion 17a and a second side surface incident portion 17b for introducing light, a first side surface incident end 5a and a second side surface, which are provided corresponding to the incident end 5a and the second side surface incident end 5b, respectively. Corresponding to each of the incident ends 5b, the first small reflection portion 18a and the second small reflection portion 18b that reflect incident light in the direction of the emission end 4 are configured. The illumination optical system 10 further includes a light source 12 and a reflection unit 13 for irradiating light to the incident end 3, and a first side for irradiating the first side incident end 5a provided in the first side incident unit 17a. 1st light source 14a, the 1st reflection part 15a, the 1st condensing means 16a, the 2nd light source 14b for irradiating light to the 2nd side surface incident end 5b provided in the 2nd side surface incident part 17b, the 2nd reflection part 15b and second condensing means 16b.

  Each of the first small reflection portion 18a and the second small reflection portion 18b has an outer shape with respect to the direction of the optical axis 8 that is 1/2 or less of the outer shape of the optical path. And the light irradiated from the 1st light source 14a and the 2nd light source 14b is condensed on each reflective surface of the 1st small reflection part 18a and the 2nd small reflection part 18b, respectively. Therefore, it is possible to reduce the loss of light emitted from the three light sources 12, 14 a, and 14 b and to emit high-luminance light from the emission end 4.

  In the fifth embodiment, the light pipe 1 can be a solid type instead of a hollow type. In addition, a large number of side surface incident ends can be provided on the side surface of the light pipe 1. Further, the small reflecting portions 18a and 18b can be concave mirrors. In addition, by making the angular distribution of the light incident from the incident end 3 substantially coincide with the angular distribution of the reflected light reflected by the first small reflection portion 18a and the second small reflection portion 18b, the light from each light source is evenly distributed. Can be mixed.

(Embodiment 6)
FIG. 7 is a schematic configuration diagram showing a projection device 30 using the illumination optical system 10 according to the sixth embodiment of the present invention. The same portions or portions having the same function are denoted by the same reference numerals. As shown in FIG. 7, the projection device 30 includes an illumination optical system 10 according to the present invention, a relay lens 31 that converts light emitted from the illumination optical system 10 into parallel light, and enters parallel light to form an image. A liquid crystal display element 32 that modulates light and an imaging optical system 33 that enlarges and projects image light emitted from the liquid crystal display element 32 onto a screen 34 are configured.

  The illumination optical system 10 includes a light incident end 3 that introduces light, a side incident end 5 that introduces light from a side surface, and a small reflector 18 that reflects light incident from the side incident end 5 in the direction of the emission end 4. A pipe 1, a light source 12, a reflection unit 13 that condenses the light from the light source 12 at the incident end 3, a light source 14, and a reflection unit 15 that condenses the light from the light source 14 at the side incident end 5. ing. Thereby, since the light inject | emitted from the output end 4 synthesize | combines the light of the light source 12 and the light source 14, high intensity | strength light can be inject | emitted. Therefore, even if the enlargement ratio of the projection image is increased, a high-luminance projection image can be formed on the screen 34. Further, if the outer shape of the light pipe 1 is, for example, several mm or less, light close to a point light source can be emitted from the emission end 4. As a result, a projection image with little distortion can be formed on the screen 34.

  The projection device 30 is not limited to the above-described configuration. For example, a reflective liquid crystal display may be used, and it is needless to say that a DMD can be used instead of the liquid crystal display element. Further, the plurality of light sources used in the illumination optical system 10 described above may have the same wavelength characteristics, may have complementary color-related wavelength characteristics, or may include three light sources. When used, light sources of red, blue, and yellow may be used.

It is typical sectional drawing showing the illumination optical system which concerns on embodiment of this invention. It is typical sectional drawing showing the illumination optical system which concerns on other embodiment of this invention. It is typical sectional drawing showing the illumination optical system which concerns on other embodiment of this invention. It is typical sectional drawing showing the illumination optical system which concerns on other embodiment of this invention. It is typical sectional drawing showing the illumination optical system which concerns on other embodiment of this invention. It is typical sectional drawing showing the illumination optical system which concerns on other embodiment of this invention. It is a typical block diagram of the projection apparatus using the illumination optical system which concerns on this invention. It is a schematic diagram of a conventionally well-known light source device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light pipe 2 Outer periphery 3 Incident end 4 Outlet end 5 Side incident end 6 Reflective surface 10 Illumination optical system 11 Inner wall surface 12, 14 Light source 13, 15 Reflective surface 16 Condensing means 17 Side incident part 18 Small reflection part 22 Small transmission part 30 Projector

Claims (7)

In the illumination optical system including the light pipe, the light incident from the incident end is repeatedly reflected and transmitted at the outer periphery of the optical path, and is emitted from the exit end.
A side incident end is provided on the side surface of the light pipe,
In the optical path of the light pipe, an illumination optical system is provided, in which a reflection surface is provided on which light incident from the side surface incident end is reflected in the direction of the emission end. Condensing means is provided at the side incident end,
The reflection surface is constituted by a small reflection portion smaller than a cross section perpendicular to the light transmission direction of the optical path,
2. The illumination optical system according to claim 1, wherein the light collected by the light collecting unit is reflected by the small reflecting portion toward the emission end. Condensing means is provided at the incident end,
The reflection surface is provided with a small transmission part smaller than a cross section perpendicular to the light transmission direction of the optical path,
3. The illumination optical system according to claim 1, wherein the light condensed by the condensing unit is transmitted through the small transmission part and emitted toward the emission end. 4.   The said light pipe is a solid type which consists of a solid member, The optical path of the said side incident end is comprised by the area | region smaller than the refractive index of the said solid member, The any one of Claims 1-3 characterized by the above-mentioned. The illumination optical system according to claim 1.   The diameter of the side incident end is smaller than the diameter of the incident end of the light pipe, and the small reflection portion is provided in the vicinity of the side incident end. The illumination optical system described in 1.   The illumination optical system according to claim 1, wherein the reflecting surface is a reflecting surface made of a concave surface.   The said side surface incident end is provided with two or more by the side surface of the said light pipe, The said reflecting surface is provided with two or more corresponding to each of these side surface incidence ends. The illumination optical system according to claim 1.