Abstract:
An illumination structure with multiple light sources in projector has first, second, third integration rods, first and second light sources. The second integration rod having a light incident surface, a light outgoing surface and a light reflection surface, is placed along the first integration rod. The light incident surface is parallel to the second integration rod, forming an angle between the light incident surface and light reflection surface. The first light source is vertically placed with respect to the second light source. The light emitted from the first light source is focused to the light incident surface of the first integration rod. The light emitted from the second light source is incident to the light incident surface of the second integration rod, and then reflected by the light reflection surface. The light reflected by the light reflection surface propagates forward the light outgoing surface of the second integration rod.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the priority benefit of Taiwan application serial no. 92128258, filed on Oct. 13, 2003.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of Invention  
         [0003]     The present invention relates to an illumination structure of projection system system. More particularly, the present invention relates to a projection system with multiple light sources and light integration device.  
         [0004]     2. Description of Related Art  
         [0005]     The digital light processing (DLP) projection system is a projecting system designed under an almost new concept, in which the image from the DLP projection system is processed. The rather conventional digital liquid-crystal (LC) projection system is also in digital manner. However, it is done by respectively projecting three-color image signals from the red, green, and blue LC panels to being overlapping on the screen, and then the color image is displayed due to the effect of light overlapping. In the digital LC projection system, the procedure for forming the image includes the steps of analog-to-digital conversion and digital-to-analog conversion, and the final image to be projected is still in analog form. During processing several conversions of image signals between digital and analog, the distortion of image inevitably occurs.  
         [0006]     The whole DLP projection system includes the light source, the optical splitter, the X-cube, and digital micromirror device (DMD). In the DLP projection system, in order to improve the uniformity of the light source, usually, an integration rod is implemented within the light path of the system. The light beam emitted from light source can enter into integration rod. After multiple times of total internal reflection in the integration rod, the light beam emits out from the integration rod, so as to produce the effect of uniformity. In order to improve the luminosity of the DLP projection system, one of the methods is using two light lamps for illumination. The conventional illumination structure for multiple light sources is basically in several ways as follows.  
         [0007]      FIG. 1  is a drawing, schematically illustrating a conventional illumination structure with multiple light sources. In  FIG. 1 , the conventional illumination structure with multiple light sources includes light sources  11   a  and  11   b  as a lamp with parabolic lamp housing, a half cube reflector  13 , a condenser lens  15  and an integration rod  17 . The parallel beam emitted from the light source  11   a  reaches to one reflection surface of the half cube reflector  13  and is reflected to the condenser lens  15 . Likewise, the parallel beam emitted from the light source  11   b  reaches to another reflection surface of the half cube reflector  13  and is reflected to the condenser lens  15 . The parallel light beams, entering to the condenser lens  15 , are condensed onto the incident surface  17   a  of the integration rod  17  by the condenser lens  15 . After multiple times of reflection in the integration rod  17 , a uniform light distribution is obtained. This illumination structure has several defects. Since the light emitted from the lamps  11   a  and  11   b  become parallel after being reflected by the lamp housing, it needs the condenser lens  15  to condense the light into the integration rod  17 . Due to the use of the condenser lens  15  in the conventional illumination structure, the emitted light cannot be completely focused onto one point, and therefore the issue of spherical aberration occurs. The aberration issue causes the increase of a spot, and the efficiency for using the light source gets worse.  
         [0008]      FIG. 2  is a drawing, schematically illustrating the second conventional illumination structure with multiple light sources. In  FIG. 2 , this illumination structure includes lamps  21   a  and  21   b , a half cube reflector  23  and an integration rod  25 . The 1.0 lamps  21   a  and  21   b  have elliptic housings. The light beams of the lamps  21   a  and  21   b  are reflected by the elliptic housings, which also produces focusing effect. As a result, when the light beams emitted from the lamps  21   a  and  21   b  reach to the reflection surface of the half cube reflector  23 , the light beams are reflected and focused onto the incident surface  25   a  of the integration rod  25 . In this illumination structure, since the elliptic housing of lamp has the function for focusing the light beams from the lamps, the condenser lens can be omitted and the volume of the whole structure can be reduced, and aberration issue can also be reduced. However, since the lamps  21   a  and  21   b  are in use, when the light beams  27   a  and  27   b  are in focusing, the transverse light cone angle is double from that in longitudinal direction. If it is desired for the integration rod  25  to have the same efficiency of light transmission as that of the structure in  FIG. 1 , the cross-sectional area of the light incident surface  25   a  is necessary to be reduced. However, since the cross-sectional area at the entrance of the integration rod  25  is reduced, then the light coupling efficiency is relatively reduced.  
         [0009]      FIG. 3  is a drawing, schematically illustrating the third conventional illumination structure with multiple light sources. In  FIG. 3 , the illumination structure includes lamps  31   a  and  31   b , and an integration rod  35 . The lamps  31   a  and  31   b  also have the elliptic housings. In this structure, the elliptic housings of the lamps  31   a  and  31   b  in this structure are designed as the cutting corner and are disposed in a row, so as to replace the function of the half cube reflector. When lamp  31   a  and  31   b  respectively emit the light beams  33   a  and  33   b , the light beams  33   a  and  33   b  are directly focused onto the incident surface  35   a  of the integration rod  35 . This structure can reduce the light cone angle of the light beam  33   a  and  33   b  when focusing, so that the cross-sectional area of the integration rod increases, resulting in increase of the coupling efficiency. However, when the light beams  33   a  and  33   b  are focused, due to the reduction of the light cone angle, the cutting area of the lamps  31   a  and  31   b  becomes large, causing the lose of light beam from other place. This further causes that the light beam cannot be focused on the integration rod  35 , and the light utility rate is reduced.  
         [0010]     From the above discussions, the conventional illumination structure with multiple light sources in the projecting system has large volume incapable of reducing the volume. The aberration produced by the condenser lens structure causes worse on the whole performance. Moreover, for the foregoing conventional structure, it cannot be avoided inevitably about some disadvantages of low optical coupling efficiency and low light utility rate.  
       SUMMARY OF THE INVENTION  
       [0011]     In one aspect, the invention provides an illumination structure with multiple light sources of a projection system, which structure can have small volume, high optical coupling efficiency, and having less issue of aberration with high light utility rate.  
         [0012]     In addition, the another aspect of the invention is to provide an illumination structure with multiple light sources of a projection system. In this structure, the lamp disposing position can be adjusted according to the different design of the projection system, and high optical coupling efficiency and high light utility rate can be maintained.  
         [0013]     For achieving the foregoing objectives, the invention provides an illumination structure with multiple light sources in a projection system. The illumination structure with multiple light sources includes a first integration rod, a second integration rod, a third integration rod, a first light source and a second light source. Usually, the light source is the lamp. The first integration rod has a light incident surface and a light emitting surface, disposed in against relation. The second integration rod is disposed longitudinally adjacent to the first integration rod. Likewise, the second integration rod also has a light incident surface and a light emitting surface, but also has a reflection surface. The incident surface is parallel to the longitudinal direction of the second integration rod, and the reflection surface and the light incident surface form an included angle with a predetermined quantity. The third integration rod, likewise, has a light incident surface and a light emitting surface, the light incident surface of the third integration rod is coupled with each of the light emitting surface of the first integration rod and the second integration rod. The first light source and the second light source are perpendicularly disposed, so that the traveling paths of the light beams emitted from the first and the second light sources are at about 90 degrees. However, other angle is still suitable. The light beam from the first light source is focused onto the light incident surface of the first integration rod, and the light beam emitted from the second light source is incident to the light incident surface of the second integration rod. After reflection by the reflection surface of the second integration rod, the light beam travels onto the light emitting surface.  
         [0014]     In the illumination structure with multiple light sources of the projection system, each of the light incident surfaces and the light emitting surfaces of the first the second and the third integration rods can be coated with an anti-reflection layer, and the reflection surface of the second integration rod is coated with a reflection layer. However, the light incident surface of the second integration rod can be only a portion of the longitudinal surface of the second integration rod.  
         [0015]     In addition, each of the light emitting surfaces of the first and the second integration rods can abut to the light incident surface of the third integration rod. In this situation, a total area of each of the light emitting surfaces of the first and second integration rods can be equal to the area of the light incident surface of the third integration rod.  
         [0016]     In the preferred condition, the included angle formed between the reflection surface and the light incident surface of the second integration rod is set to 45 degrees.  
         [0017]     From the other aspect of the invention, the invention further provides an illumination structure with multiple light sources in a projection system, including a first integration rod, a second integration rod, a third integration rod, a first light source, and a second light source. Usually, the light sources are lamps. The first integration rod has a light incident surface, a light emitting surface, and a reflection surface, wherein the light incident surface is parallel to the longitudinal direction of the first integration rod, and a predetermined included angle is formed between the reflection surface and the light incident surface. Likewise, the second integration rod has a light incident surface, a light emitting surface, and a reflection surface, wherein the light incident surface is parallel to the longitudinal direction of the second integration rod, and a predetermined included angle is formed between the reflection surface and the light incident surface. The third integration rod has a light incident surface and a light emitting surface. Each of the light emitting surfaces of the first and the second integration rods is coupled with the light incident surface of the third integration rod. The first light source and the second light source are disposed in against relation, so that the light beams emitted from the first and the second light sources are traveling in parallel. Wherein, the light beam emitted from the first light source is incident to the first integration rod from the light incident surface, and travels toward the light emitting surface after reflection by the reflection surface of the first integration rod. The light beam emitted from the second light source is incident onto the light incident surface of the second integration rod, and then travels to the light emitting surface after reflection by the reflection surface of the second integration rod.  
         [0018]     In the illumination structure with multiple light sources of the projection system, each of the light incident surfaces and the light emitting surfaces of the first the second and the third integration rods can be coated with an anti-reflection layer, and the reflection surfaces of the first and the second integration rods is coated with a reflection layer. However, each light incident surface of the first and the second integration rods can be only a portion of the longitudinal surface of the first and the second integration rods, respectively.  
         [0019]     In addition, each of the light emitting surfaces of the first and the second integration rods can abut to the light incident surface of the third integration rod. In this situation, a total area of each of the light emitting surfaces of the first and second integration rods can be equal to the area of the light incident surface of the third integration rod.  
         [0020]     In the preferred condition, the included angle formed between the reflection surface and the light incident surface of the first and the second integration rods is set to 45 degrees.  
         [0021]     In another aspect of the invention, the invention further provides an illumination structure with multiple light sources in a projection system, including at least two integration rods, at least two light sources, and a third integration rod. Wherein, the at least two integration rods respectively have a light incident surface and a light emitting surface, in against relation. The at least two light sources relatively disposed, so that the light beams emitted from the light sources can be focused and incident onto the light incident surfaces of the integration rods. The third integration rod has a light incident surface and the light emitting surface, which are disposed so as to allow each of the light emitting surfaces coupled to the light incident surface of the third integration rod.  
         [0022]     The invention also has another object to provide a light integration device of a projection system, including at least two integration rods and a third integration rod. Wherein, the at least two integration rods respectively have a light incident surface and a light emitting surface, in against relation. The third integration rod has a light incident surface and the light emitting surface, which are disposed so as to allow each of the light emitting surfaces coupled to the light incident surface of the third integration rod.  
         [0023]     From the foregoing descriptions, according to the illumination structure with multiple light sources in a projection system, the light beams from the lamps, which serve as the light sources, can be directly focused onto the light incident surface of the integration rod, the condenser lens can be saved. This can reduce the volume of the projection system, but also does not produce aberration. IN addition, since the light is directly focused onto the integration rod, the light coupling rate can increase.  
         [0024]     In addition, in the invention, the light beam is directly focused onto the integration rod. However, due to the difference of the disposing positions, the light does not be scattered in loss. The light utility rate is greatly improved. In addition, in the invention, the lamp position can be flexibly arranged according to the difference of design in outer appearance. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
         [0026]      FIG. 1  is a drawing, schematically illustrating one conventional illumination structure with multiple light sources.  
         [0027]      FIG. 2  is a drawing, schematically illustrating a second conventional illumination structure with multiple light sources.  
         [0028]      FIG. 3  is a drawing, schematically illustrating a third conventional illumination structure with multiple light sources.  
         [0029]      FIG. 4A  is a drawing, schematically illustrating an illumination structure with multiple light sources of projection system, according to a preferred embodiment of the present invention.  
         [0030]      FIG. 4B  is a drawing, schematically illustrating an illumination structure with integration rod, according to the preferred embodiment of the present invention.  
         [0031]      FIG. 4C  is a perspective view, schematically illustrating the portion of the expanded integration rod.  
         [0032]      FIG. 5  is a drawing, schematically illustrating the optical coating on each surface of the integration rod, according to a preferred embodiment of the present invention.  
         [0033]      FIG. 6A  is a drawing, schematically illustrating an illumination structure with multiple light sources of projection system, according to another preferred embodiment of the present invention.  
         [0034]      FIG. 6B  is a drawing, schematically illustrating an illumination structure with the magnified integration rod, according to the preferred embodiment of the present invention.  
         [0035]      FIG. 7  is a drawing, schematically illustrating optical coating process on each surface of the integration rod, according to the preferred embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]     The illumination structure with multiple light sources of a projection system in the invention mainly uses three integration rods in place of the conventional design with one integration rod. The advantage is that the light beams emitted from the lamps can be directly focused onto the integrations rod and it is not necessary to have the cutting-angle design on the lamp housing. The light beam emitted from each lamp can pass an integration rod, and then further collected by the third integration rod. After the total internal reflections for getting uniform, the light beams are led out from the integration rod. In the following embodiment, the longitudinal direction is defined as the direction of the longer optical axis of the integration rod, that is, the traveling direction of the light in the integration rod.  
         [0037]      FIG. 4A  is a drawing, schematically illustrating an illumination structure with multiple light sources of projection system, according to a preferred embodiment of the present invention.  FIG. 4B  is a drawing, schematically illustrating an illumination structure with integration rod, according to the preferred embodiment of the present invention.  FIG. 4C  is a perspective view, schematically illustrating the portion of the expanded integration rod. In  FIG. 4A  to  FIG. 4C , the invention provides an illumination structure with multiple light sources of projection system, including a first integration rod  41 , a second integration rod  43 , a third integration rod  45 , and a first lamp  47   a  with a second lamp  47   b , serving as the light source. The integration rods can be, for example, glass bodies. The first integration rod  41  has the light incident surface  41   a  and the light emitting surface  41   b . The light incident surface  41   a  and the light emitting surface  41   b  are opposite to each other, and are disposed in parallel. The second integration rod  43  similarly has the light incident surface  43   a  and the light emitting surface  43   c , and the second integration rod  43  further has the reflection surface  43   b . Likewise, the light incident surface  43   a  and the light emitting surface  43   c  are against to each other, and are disposed in parallel. The light incident surface  43   a  is parallel to the longitudinal direction of the second integration rod  43 . The reflection surface  43   b  and the light incident surface  43   a  includes a predetermined angle φ1, so that the integration rod  41  has the trapezoid shape at the cross-sectional view. The predetermined angle φ1 is designed for allowing the light beam emitted from the second lamp  47   b  to be incident to the second integration rod  43 , and then reflected at the reflection surface  43   b  so as to longitudinally travel forward in the second integration rod. As a result, under the foregoing structure, when the light of the second lamp  47   b  is incident about perpendicular to the light incident surface  43   a , the predetermined angle φ1, included between the reflection surface  43   b  and the light incident surface  43   a  of the second integration rod  43  is preferably set to be 45 degrees. Alternatively, the angle φ1 can be adjusted according to the location of the second lamp  47   b.    
         [0038]     The longitudinal side of the integration rod  43  is parallel to the longitudinal side of the first integration rod  41 , and the second integration rod  43  is abutting to the first integration rod  41  in the longitudinal direction. The third integration rod  45  also has the light incident surface  45   a  and the light emitting surface  45   b , wherein the light incident surface  45   a  and the light emitting surface  45   b  are arranged in a way like the first integration rod  41 . The light emitting surface  41   b  of the first integration rod  41  and the light emitting surface  43   c  of the second integration rod  43  are coupled to the light incident surface  45   a  of the third integration rod  45 . The light emitting surfaces  41   b  and  43   c  are abutting to the light incident surface  45   a . In the embodiment, the lamp housings, such as elliptic lamp housing, of the first lamp  47   a  and the second lamp  47   b  have the function for focusing the light beam. As shown in  FIG. 4A , the axes  470 ,  472  of the first lamp  47   a  and the second lamp  47   b  are perpendicular to each other, so that the light paths of the emitted light beams are traveling by 90 degrees. However, other implementation angle can also be used.  
         [0039]     As shown in  FIG. 4C , preferably in the embodiment, the light emitting surface  41   b  of the first integration rod  41  and the light emitting surface  43   c  of the integration rod  43  are abutting to the light incident surface  45   a  of the third integration rod  45 . In addition, the total area of the light emitting surface  41   b  of the first integration rod  41  and the light emitting surface  43   c  of the integration rod  43  is equal to the area of the light incident surface  45   a  of the third integration rod  45 .  
         [0040]     Still referring to  FIG. 4B , the light traveling path is described. The light beam emitted from the first lamp  47   a  is focused by elliptic lamp housing and incident to the light incident surface  41   a  of the first integration rod  41 . The incident light beam has multiple times of total internal reflection in the integration rod  41 , and then uniformly emits out from the light emitting surface  41   b . The light beam emitted from the light emitting surface  41   b  is incident to the third integration rod  45  at the light incident surface  45   a . Moreover, the light beam emitted from the second lamp  47   b  is focused by elliptic lamp housing and incident to the light incident surface  43   a  of the second integration rod  43 . The incident light beam is reflected by the reflection surface  43   b  in the second integration rod  43 , and then travels toward the light emitting surface  43   c . After multiple times of total internal reflection, the light beam uniformly emits out from the light emitting surface  43   c . The light beam emitted from the light emitting surface  43   c  is incident to the third integration rod  45  at the light incident surface  45   a . After the light beam in incident to the third integration rod  45 , likewise, the light beam is internally reflected by multiple times, and then emits at the light emitting surface  45   b.    
         [0041]     In order to more effectively achieve the above objectives, the invention further processes the light incident surface, the light emitting surface, and the reflection surface of the integration rod.  FIG. 5  is a drawing, schematically illustrating the optical coating on each surface of the integration rod, according to a preferred embodiment of the present invention. Referring to  FIGS. 4A, 4B  and  5 , in the embodiment, usually, when the light beam is incident into a medium from the light incident surface, a portion of the light is inevitably reflected at the incident surface, and cannot cause all of the light beam to enter the medium. Likewise, in order to allow the light incident to be more efficient in the structure of the invention, the light incident surface is processed by an optical coating film. For example, the light incident surface  41   a  and the light emitting surface  41   b  of the first integration rod  41 , the light incident surface  43   a  and the light emitting surface  43   c  of the second integration rod  43  and the light incident surface  45   a  and the light emitting surface  45   b  of the third integration rod  45  are coated with an anti-reflection layer  51 , so that when the light beams are incident to the surfaces, the utility rate of the light beam is not reduced during the reflection. Also and, the reflection surface  43   b  of the second integration rod  43  is coated with a reflection layer  53 , so that when the light beam is incident to the reflection surface, it can be almost reflected without transmission. As a result, this can prevent the light loss from occurring, causing the reduction of the utility rate. Here, the light incident surface  43   a  of the second integration rod  43  is only a portion of the longitudinal surface  43   d  of the second integration rod  43 .  
         [0042]      FIG. 6A  is a drawing, schematically illustrating an illumination structure with multiple light sources of projection system, according to another preferred embodiment of the present invention.  FIG. 6B  is a drawing, schematically illustrating an illumination structure with the magnified integration rod, according to the preferred embodiment of the present invention. In  FIG. 6A  and  FIG. 6B , the difference of this embodiment from the previous embodiment is the disposed positions of the first lamp  67   a  and the second lamp  67   b . In this embodiment, the first lamp  67   a  and the second lamp  67   b  are disposed in against manner, so that the light beams emitted from the first lamp  67   a  and the second lamp  67   b  are traveling in parallel and against. In addition, the two lamps  67   a ,  67   b  are perpendicularly incident to the longitudinal side surface of the integration rods. Comparing with the first integration rod  41  of the previous embodiment, since the first lamp  67   a  is disposed at the different position, the first integration rod  61  has also been modified. As shown in  FIG. 6B , the integration rod  61  of this embodiment also has a light incident surface  61   b  and a light emitting surface  61   c . However, since the light beam emitted from the first lamp  67   a  is perpendicular to the longitudinal side surface of the first integration rod  61 , the light incident surface  61   b  is arranged to be parallel to the longitudinal side surface of the first integration rod  61 . Here, the end surface abutting to the light incident surface  61   b  of the first integration rod  61  (perpendicular to the longitudinal side surface) is cut in tilt by a predetermined angle φ2, so that the inner side of the tilt cutting surface of the integration rod  61  is used as the reflection surface  61   a . In other words, the reflection surface  61   a  and the incident surface  61   b  include a predetermined angle φ2. With the function of the reflection surface  43   b  of the second integration rod  43  in previous embodiment, the reflection surface  61   a  is used to allow the light beam, which is emitted from the first lamp  67   a  and is incident to the light incident surface  61   b , to travel toward the light emitting surface  61   c  after being reflected by the reflection surface  61   a . In this structure, when the light beam of the first lamp  67   a  is about perpendicularly incident to the ling incident surface  61   b , the predetermined angle φ2, which is included between the reflection surface  61   a  and the light incident surface  61   b  of the first integration rod  61 , is preferably set to be 45 degrees. In addition, since the way of disposing positions of the second lamp  67   b  and the second integration rod  63  are similar to the first lamp  67   a  and the first integration rod  61 , the reflection surface  63   a  and the light incident surface  63   b  of the second integration rod  63  also include a predetermined angle φ2, like that in the first integration rod  61 . This predetermined angle φ2 is also preferably set to be 45 degrees. The function of the second integration rod  63  in the embodiment is similar to the second integration rod  43  in previous embodiment, and is not repeatedly described.  
         [0043]     Still referring to  FIG. 6B  about the light traveling path, in the embodiment, the traveling path of the light beam from the second lamp  67   b  is similar to the traveling path from the second lamp  47   b  in the previous embodiment, referring to previous embodiment. The light beam emitted from the first lamp  67   a  is incident to the light incident surface  61   b  of the first integration rod  61 , and travels toward the light emitting surface  63   c  after being reflected by the reflection surface  61   a  of the first integration rod  61 . After multiple times of total internal reflection in the first integration rod  61 , the light beam is uniformly emitted from the light emitting surface  61   c  and immediately enters the third integration rod  65  from the light incident surface  65   a . Likewise, the light beam in the third integration rod  65  has multiple times of total internal reflection and then is uniformly emitted from the light emitting surface  65   b.    
         [0044]      FIG. 7  is a drawing, schematically illustrating optical coating on each surface of the integration rod, according to the preferred embodiment of the present invention. In  FIG. 5A ,  FIG. 5B , and  FIG. 7 , with the similar reasons in previous embodiment, the surfaces of the integrations rod have been processed with optical coating films. In this embodiment, the process of optical coating films on the second and the third integration rod are similar to that in  FIG. 5A , without repeated description. However, the surface coating process on the surfaces of the first integration rod  61  is looked into. The light incident surface  61   b  and the light emitting surface  61   c  of the integration rod  61  are coated with anti-reflection layer  51 , so that when the light is incident on the surfaces, the utility rate of the light beam is not reduced caused by the light reflection. Also and, the light emitting surface  61   a  is coated with a reflection layer  52 , so that when the light beam is incident to the reflection surface  61   a , the light beam can be almost all reflected without transmission. This can prevent the light loss from occurring, causing the low utility rate of the light beam. Likewise, the light incident surface of the first integration rod  61  is only a portion of the longitudinal side surface  63   d  of the first integration rod  63 .  
         [0045]     In summary, according to the illumination structure with multiple light sources in the invention, since each lamp is with respect to an integration rod, the light cone angle of each lamp can maintain the same effect as that with the structure in single lamp. In addition, according to Etendue optical design theory, the product of the light cone angle and the cross-sectional area of the integration rod is a constant. In this manner, the cross-sectional area of the structure of the invention is not reduced. In other words, the cross-sectional area is not reduced, the light coupling ratio is not reduced either.  
         [0046]     Even though the forgoing embodiments use the example for descriptions, implemented by the first integration rod, the second integration rod, the first lamp, and the second lamp, the invention is not limited to this implementation. The implementation manner is not necessary to be limited in the structure elements.  
         [0047]     That is, according to the structure of the invention, the end surface of the integration (perpendicular to the longitudinal direction) is designed according to the lamp position. For example, when the light beam from the lamp is focused and is incident to the end surface of the integration rod, the end surface is not necessary to be processed with tilt cutting. In this situation, it has been sufficient to coat the anti-reflection layer thereon. In addition, if the light beam from the lamp is perpendicularly incident to the integration rod from the longitudinal side surface, then the end surface adjacent to the light incident surface is cut by a predetermined tilt angle, so as to allow the light beam to be reflected, as foregoing descriptions, and longitudinally travels along the integration rod. Therefore, in the design principle, no matter how to implement any number of the lamps and the integration rod at any positions, any design at the end satisfies the forgoing design principle is the feature of the invention.  
         [0048]     When it has a plurality of lamps (assuming to have N lamps), according to the design principle of the invention, it needs no more than N+1 of integration rods. N of the integration rods are with respect to the number of the light sources one to one, and the additional one of the integration rods is used to collect the light beams from the N of integration rods. As to which one of the integration rods is to be cut at the end surface, it is then depending on the positions of the lamps.  
         [0049]     From the foregoing embodiments, the illumination structure with multiple light sources in a projection system of the invention, if the lamp housing of the lamp is, for example, the elliptic lamp housing, it automatically has the focusing function when the light beam is reflected. Therefore, it needs not to use the condenser lens and the half cube reflector without causing the aberration issue, so that the volume can be reduced. In addition, since the light beam from the light source provided by the invention is directly focused on the integration rod, the light cone angle can be reduced.  
         [0050]     Even though the light source provided by the invention is directly focused on the integration rod, the light source of the invention needs no the cutting corner. Instead, it is achieved by disposing at different positions. This not only causes the light beam be not easy in scattering loss, so as to increase the utility rate of the light, but also allows the implementing positions of the light sources to be freely adjusted, according to the different design of the projecting system.  
         [0051]     It will be apparent to those skilled in the art that various modifications and variations can be made to the illumination structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing descriptions, it is intended that the present invention covers modifications and variations of this invention if they fall within the scope of the following claims and their equivalents.