Abstract:
An image projector having a LED light source comprises: an optical engine using the LED as the light source, a PCB module, a heat sink module and a main frame. The printed circuit board (PCB) module further comprises: a first circuit board, a second circuit board, at least one I/O interface for connecting an external device, at least one card reader for connecting an external memory card, and a control unit for processing the image data received from the I/O interface or card reader and projecting the image by using the optical engine. The first circuit board and second circuit board are furnished in an overlap and parallel manner to decrease the space consumption. The heat sink module comprises a fan, an air inlet and an air outlet, which substantially forms a heat dissipating passage from the air inlet through the fan toward the air outlet. The LED and control unit are located in the heat dissipating passage for increasing better heat dissipation effect.

Description:
BACKGROUND OF INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention is related to an image projector; in particular, is related to an image projector having a LED as the light source.  
         [0003]     2. Description of the Prior Art  
         [0004]     The conventional image projector has reached the threshold in effectively sizing down due to the limitation in the design of the optical engine, the PCB module and the heat-dissipating route. On one hand, the complexity of the optical elements and the design of the light path prevented smaller space usage in designing the image projector; on the other hand, the complexity and the numerous electronic elements used prevented the minimization of the printed circuit board (PCB). Moreover, the large quantity of heat generated by the illuminator of the optical engine and the microprocessor of the PCB module has to be effectively dissipated by using two or more units of bigger-size high power fan combined with a wide, smooth heat-dissipating route in the image projector produced. In conclusion, the space taken up by the heat dissipating route and the fan prevented the effective minimization of the size of the image projector produced by custom technology.  
       SUMMARY OF INVENTION  
       [0005]     It is therefore one of the objectives of the claimed invention to provide an image projector that utilizes a light emitting diode (LED) as its illuminator. The image projector could dramatically decrease its size without affecting the efficiency and function thereof.  
         [0006]     It is therefore one of the objectives of the claimed invention to provide an image projector that utilizes a light emitting diode (LED) as illuminator that includes two horizontally overlapping PCBs as its PCB module to reduce the space usage of itself. This design, as a result, enhances the reduction in size of this image projector.  
         [0007]     It is therefore one of the objectives of the claimed invention to provide an image projector that utilizes a light emitting diode (LED) as its illuminator, with the special design for its heat dissipating module which separately places the heat generating light emitting diode and the PCB control unit, the former, near the vicinity of the entrance airway and the later, near the fan of the heat sink module, to enhance the effect of heat dissipation. Therefore, the image projection device in this invention can utilize a single and yet smaller heat dissipating fan which has smaller power, combined with a narrower heat dissipating route to effectively dissipate the heat generated by the device. This design further reduced the size of the image projector.  
         [0008]     It is therefore one of the objectives of the claimed invention to provide an image projector that utilizes a light emitting diode as its illuminator so that the heat generation is effectively reduced, and favors the minimization of the size of the heat-dissipating module. Furthermore, the size of the image projector can be further diminished due to the special design of the optical elements and illumination pathway that reduces the dimensions of the optical engine.  
         [0009]     It is therefore one of the objectives of the claimed invention to provide an image projector that utilizes a light emitting diode as illuminator, which contains a card reader that can be connected to a memory card. This device can directly retrieve the image data that is stored in the memory card and project it through the optical engine.  
         [0010]     In accordance with these aspects of the present invention, an optical engine having a LED is provided, which comprises: an optical engine using the LED as the light source, a PCB module, a heat sink module and a main frame. The printed circuit board (PCB) module further comprises: a first circuit board, a second circuit board, at least one I/O interface for connecting an external device, at least one card reader for connecting an external memory card, and a control unit for processing the image data received from the I/O interface or card reader and projecting the image by using the optical engine. The first circuit board and second circuit board are furnished in an overlap and parallel manner to decrease the space consumption. The heat sink module comprises a fan, an air inlet and an air outlet, which substantially forms a heat dissipating passage from the air inlet through the fan toward the air outlet. The LED and control unit are located in the heat dissipating passage for increasing better heat dissipation effect. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The details of the present invention will be more readily understood from a detailed description of the preferred embodiments taken in conjunction with the following Figures.  
         [0012]      FIG. 1  illustrates the frontal stereoscopic view of the exterior appearance of the image projector that utilizes a light emitting diode as illuminator;  
         [0013]      FIG. 2  illustrates the posterior stereoscopic view of the exterior appearance of the image projector as shown in  FIG. 1 ;  
         [0014]      FIG. 3  illustrates a perspective view of such image projector as in  FIG. 1  from a different angle;  
         [0015]      FIG. 4  illustrates a composite drawing of the internal optical engine, PCB module and the lower frame of the main frame of the image projector as shown in  FIG. 1 ;  
         [0016]      FIG. 5  illustrates the composite drawing of the heat dissipating module, operation interface module and the upper frame of the main frame of the image projector as shown in  FIG. 1 ;  
         [0017]      FIG. 6  shows a diagram of the heat-dissipating pathway of the heat flow of the image projector of  FIG. 1  according to the present invention;  
         [0018]      FIG. 7  illustrates the three-dimensional diagram of the optical engine of the image projector according to the present invention; and  
         [0019]      FIG. 8  illustrates the three-dimensional diagram of the illumination module of the image projector according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]     Please refer to  FIG. 1  to  FIG. 5 . The figures describe a preferred embodiment of the image projector that utilizes a light emitting diode (LED) as its illuminator according to the present invention.  FIG. 1  illustrates the frontal stereoscopic view of the exterior appearance of the image projector that utilizes a light emitting diode as illuminator.  FIG. 2  illustrates the posterior stereoscopic view of the exterior appearance of the image projector as shown in  FIG. 1 .  FIG. 3  illustrates a perspective view of such image projector as in  FIG. 1  from a different angle.  FIG. 4  illustrates a composite drawing of the internal optical engine, PCB module and the lower frame of the main frame of the image projector as shown in  FIG. 1 .  FIG. 5  illustrates the composite drawing of the heat sink module, operation interface module and the upper frame of the main frame of the image projector as shown in  FIG. 1 .  
         [0021]     As shown in  FIGS. 3, 4  and  5 , the image projector  1  of this invention that utilizes a light emitting diode (LED) as illuminator includes: an optical engine  10 , a PCB module  20 , a heat sink module  30 , a operation interface module  40 , a main frame and a casing  50 .  
         [0022]     The optical engine  10  is used for projecting an image. There is a light emitting diode (LED)  111  (as shown in  FIG. 8 ) in the optical engine  10  that produces the light needed for the projection of an image.  
         [0023]     The printed circuit board (PCB) module  20  is connected to the optical engine  10  in order to control the projection of the optical engine. The PCB module  20  includes: a first PCB  22  and a second PCB  23  that are set-up in parallel to each other; at least one connecting interface  21  (such as USB interface or AV terminal) for connecting an external device (such as computer or DVD player); at least one card reader  24  (such as flash memorycard reader) for connecting an external memory card (such as CF Card or SmartMedia Card or MMC or SD or MS Card); and a control unit  25  to process the image data received from the connecting interface  21  or card reader  24  and then project the image through the optical engine  10 . In a preferred embodiment, the first PCB  22  and the second PCB  23  are horizontally overlaped with each other. The dimension of the first PCB  22  is smaller than the second PCB  23 . This provides an area on the second PCB  23  that will not overlap with the first PCB  22 . In the design, the card reader  24  is set up on the first PCB  22 . The heat-dissipating fan  31  is set up on the supporting plate  26  on the second PCB  23  that does not overlap with the first PCB  22 . The control unit  25  is positioned on the second PCB  23  and does not overlap with a heat-dissipating fan  31 . The design of this invention, which includes a PCB module  20  including two overlapping PCB  22 , 23  and the heat dissipating fan  31  being positioned on the area on the second PCB  23  that does not overlap with the first PCB  22 , enables a more economical use of space which significantly reduces the dimensions of the image projector  1  of this invention. Also, this design enables higher heat dissipating efficiency due to the reason that the heat-dissipating fan can be placed closer to the heat generating electronic elements such as the microprocessor.  
         [0024]     The heat sink module  30  is used for dissipating the heat generated by the optical engine  10  and the PCB module  20 . The heat sink module  30  comprises at least a heat dissipating fan  31 , an entrance airway  33  and an exit airway  32 , which in fact build into a heat dissipating route that starts from the entrance airway  33  then passes through the heat dissipating fan  31  and then ends at the exit airway  32  (The arrow in  FIG. 6  shows the direction of the heat flow in the heat dissipating pathway). Also, the light emitting diode  111  and the control unit  25  are positioned on the heat-dissipating route. In this preferred embodiment, the exit airway  32  of the heat sink module  30  is at one of the front flank of the lower frame  61  of the supporting frame. The heat-dissipating fan  31  is placed at the vicinity of the exit airway  32  and close to the control unit  25 . The entrance airway  33  is positioned at the posterior flank of the lower frame  61  of the supporting frame, which is close by the illumination PCB  114  that contains the light emitting diode  111 . Therefore, better heat dissipating effect is achieved due to the reason that the light emitting diode  111  receives the cool air that enters through the entrance airway  33 , while the control unit  25  dissipates the heat faster by the concentrated airflow that passes through the close-by heat-dissipating fan  31 . This designed heat sink module  30  enables the image projector  1  of this invention to eliminate the need of two or more fans or fan with big size of higher power to achieve excellent heat-dissipating effect. It also has the benefit of cutting down the space usage and electricity consumption. Thus, the image projector  1  of this invention needs only one heat-dissipating fan  31  of low power and size together with a heat-dissipating route of less width than usual to achieve efficient heat-dissipating effect, and therefore enables the minimization of the size of the image projector  1 .  
         [0025]     The operation interface module  40  is connected to the PCB module  20  for the operations of the image projector  1  according to this invention. The operation interface module  40  includes but not limits a power switch of the image projector  1 , video signal converter, the adjustment of projection proportion and focus, projection angle or brightness. In a preferred embodiment, the operation interface module  40  includes several keys  41 , a keyboard  42  and a keyboard PCB  43 . The keyboard PCB  43  is connected to the upper frame  62 , while the keyboard  42  and keys  41  are sequentially assembled on the keyboard PCB  43 . The abovementioned components are only a preferred embodiment of the invention and not for giving any limitation to the scope of the present invention.  
         [0026]     The supporting frame is used to contain and position the optical engine  10 , the PCB module  20 , the heat sink module  30  and the operation interface module  40 , which were described previously. In this preferred embodiment, the supporting frame includes a lower frame  61  and an upper frame  62 . There are several screw holes and sockets at the predetermined area of the lower frame  61  and upper frame  62  so that the optical engine  10 , the PCB module  20 , the heat sink module  30  and the operation interface module  40  can be screwed on to the predetermined area and the elements such as connection interface  21  and keys  41  can be exposed external of the casing  50 . Through this assembly, the upper and lower frames  62 , 61  of the supporting frame can integrate the optical engine  10 , PCB module  20 , heat sink module  30  and operation interface module  40  into the image projector  1 . Thus, the designer of the image projector  1  of this invention only needs to overlay different designs for the casing  50  on only one unit of the supporting frame that includes all the elements for the image projector  1 , for the diversification of the product. The designer does not have to design different supporting frame for each of the different outer casing. This invention provides for the effect of design-modularization.  
         [0027]     Please refer to  FIG. 7  and  FIG. 8 . These figures illustrate the preferred embodiments of the optical engine  10  of the image projector  1  according to this invention.  FIG. 7  illuminates the three-dimensional diagram of the optical engine  10  of the image projector  1  of this invention.  FIG. 8  shows the three-dimensional diagram of the illumination module  11  of the image projector  1  of this invention.  
         [0028]     As shown in  FIG. 7  and  FIG. 8 , the optical engine  10  of this invention includes: an illuminator module  11 , a concave mirror  12 , a condenser  13 , a prism module  14 , a Digital Micromirror Device (DMD)  15  and a projection lens set  16  put together by several lenses  161  and an aperture  162 . The formation of the image at an external surface is by the following process: firstly, the dispersed rays of the light emitted by the light-emitting diode  111  of the illumination module  11  is concentrated by the pyramidal pole  112  of the illumination module  11 . A concave mirror  12  then collects and refracts the concentrated rays to the converging lens  13 , which collects the rays and pass it towards the prism module  14  that refracts the rays towards the DMD  15 . The DMD  15  reflexes the rays and produces images that is again refracted by the prism module  14  towards the projection lens set  16 , focuses the image and then forms image at the external projection surface.  
         [0029]     To precisely orient all the elements described previously, the optical engine  10  of this invention has a special orientation mechanism. As shown in  FIG. 7 , the optical engine further includes a base  17  and an upper lid  18 . In this embodiment, it is better to produce the base  17  and the upper lid  18  by plastic injection molding. On the base  17 , a right cover  171  and a lower lid  172  are also included. The right cover  171  forms a first space  173  to contain the DMD  15 . The lower lid  172  on the other hand, forms a v-shape lower concave base  174 , which adjoins with a below-prism shading piece  175  at the right cover  171 . It also forms a below-concave groove  176  in between the v-shape lower concave base  174  and the below-prism shading piece  175 . The upper lid  18  can be connected to the lower lid  172  on the base  17 . Moreover, there is a v-shape upper concave base  181 , an above-prism shading piece  182  and an above concave groove (not shown in the FIG.) on the upper lid  18 . The position of the upper concave base  181 , the above-prism shading piece  182  and the above concave groove each respectively corresponds to the v-shape lower concave base  174 , the below-prism shading piece  175  and the below-concave groove  176 . When the upper lid  18  shuts with the lower lid  172 , a containing space is formed between the two lids. When assembling the optical engine  10  of this invention, the prism module  14  is contained between the above-prism shading piece  182  and the below-prism shading piece  175 . The converging lens  13  is contained between the above-concave groove and the below-concave groove  176 . The concave mirror  12  is contained between the v-shape upper concave base  181  and the bended area of the v-shape lower concave base  174 . Also, the pyramidal pole  112 , the fixing stand  115  and the spring clip  116  are contained between the v-shape upper concave base  181  and the end of the v-shape lower concave base  174 . In addition, under the lower surface of the prism module  14 , there is a prism supporting board  143  and a spring  144  that is used for orienting and micro-adjusting the relative position of the prism module  14 . As a result, using the specially designed structure of the base  17  and the upper lid  18 , one can rapidly, easily and precisely assemble each element at its predetermined angle, relative position and distance.  
         [0030]     The DMD  15  further includes: a DMD chip  151 , a DMD socket  152  for the DMD chip  151  to plug in, a DMD PCB  153  to connect to the DMD socket  152 , and a DMD power connector  154  to connect to the DMD PCB  153 . When DMD  15  is assembled to the right lid  171  of the base  17 , the DMD chip  151  would be exposed at a window located at the center of the first space  173 . This enables the DMD chip to receive light from the prism module  14 . The projection lens set  16  is located at an opening in between the above-prism shading piece  182  and the below-prism shading piece  175 . The projection lens set  16  also includes a rubber  163  and a fastening ring  164 . The rubber  163  can be put around the exterior of the projection lens set  16 , and the contour of the rubber  163  can seal the space between the above-prism shading piece  182  and the below-prism shading piece  175  to prevent disturbance due to light leakage. The fastening ring  164  locks the projection lens set  16  on the extension frame  177  of the right lid  171 .  
         [0031]     In this preferred embodiment, the prism module  14  is of the reversed total internal reflection (RTIR) design. It includes: a first prism  141 , a second prism  142  and a prism supporting board  143 . The first prism  141  is placed closer to converging lens  13  while the second prism is placed closer to the DMD  15 . Both first and second prisms  141 , 142  are made from transparent material that has a predetermined reflective index. The first prism  141  is a wedge prism. The cross section in which the direction of the light beam passes is conical in shape. The second prism  142  is a right angle prism. The cross section in which the direction of the light beam passes is a right triangle. Also the first prism  141  is attached to hypotenuse surface of the right triangle of the cross section of the second prism  142 . The DMD  15  and the projection lens  16  are respectively placed on the two perpendicular surfaces of the right triangle of the cross section of the second prism  142 .  
         [0032]     As shown in  FIG. 8 , the illuminator module  11  includes: a light emitting diode  111 , a pyramidal pole  112 , a light reflective measure, a PCB  114 , a fixing stand  115  and a spring clip  116 . A heat-dissipating element  117  is combined to the illuminator module to enhance heat-dissipation.  
         [0033]     The light emitting diode  111  is used for emitting light at a predetermined beam axis. In this invention, one end of the pyramidal pole  112  is closer to the light emitting diode  111 . The pyramidal pole  112  has several numbers of narrow and long surfaces  1121  that extends in the direction of the beam axis. In this preferred embodiment, the cross section of the pyramidal pole  112  that is perpendicular to the beam axis has a square contour. Each narrow and long surfaces  1121  respectively has two opposite long edges that follows the direction of the beam axis  1122 ,  1123  and two opposite short edges that is perpendicular to the beam axis  1124 , 1125 . Also, the short edge  1125  on the narrow and long surface  1121  closer to the light emitting diode  111  is shorter compared to the short edge  1124  that is further away from the light emitting diode  111 . In this case, the cross section of the pyramidal pole  112  in essence, increases in size as furthering away from the light emitting diode  111 . The concave mirror  12  is located at the end of biggest cross section of the pyramidal pole  112 .  
         [0034]     This reflective measure that was utilized in each narrow and long surfaces  1121  of the pyramidal pole let the narrow and long surfaces  1121  reflex the light beam emitted by the light emitting diode  111 , which guides the light beam to move along the beam axis. In the preferred embodiment in  FIG. 8 , the pyramidal pole  112  is a hollow conical structure that is better made of transparent materials. However, glass, plastic crystals and quartz can also be used. The reflective measure is such that the inner surface of each narrow and long surfaces  1121  of the hollow pyramidal pole  112  are coated with reflective material (such as silver, etc), which enables the total reflex of the light in the hollow pyramidal pole  112  and passing of the light beam from the smaller cross section towards the larger cross section of the pyramidal pole  112 . In this case, the pyramidal pole  112  in this invention could achieve the purpose of generally directing the light beam to move along the beam axis.  
         [0035]     The PCB  114  is used to support the light emitting diode  111 . There are also several electronic elements (not numbered) to drive the light emitting diode  111  and a connector  1142 . The fixing stand  115  is connected to the PCB  114 . On the fixing stand  115 , there is an approximately square shape hollow sink  1151  in which the smaller cross section end of the pyramidal pole  112  can fit in. Also, the position of the light emitting diode  111  respectively fits in with the smaller cross section end of the pyramidal pole  112 . Moreover, the fixing stand  115  has two stands  1152 , 1153  and a sliding route  1154  positioned between the two stands. The dimensions of the sliding route  1154  matches the dimensions of the PCB  114 , so that the PCB  114  can slide into the sliding route  1154  to connect with the fixing stand  115 .  
         [0036]     The spring clip  116  clips and secures the pyramidal pole  112  on the fixing stand  115 . In this preferred embodiment, the spring clip  116  further includes several clips  1161 , at least one buttoning clip  1162  on one of the clips  1161 , and holes  1163  located in between each clips  1161 . The dimensions of the holes are bigger than that of the largest cross section of the pyramidal pole  112 . When the holes  1163  of the spring clip  116  slip onto the pyramidal pole  112 , and at least one of the clips  1161  clips on to the edge of the fixing stand  115 , the pyramidal pole  112  can be connected and fixed on the fixing stand  115 . In this preferred embodiment, a bump  1126  can be set up on at least one narrow and long surface  1121  of the pyramidal pole  112 , so that when the hole  1163  of the spring clip  116  slips onto the pyramidal pole  112 , the bump  1126  can exactly sustain the spring clip  116  and the fixing stand  115  to prevent shifting.  
         [0037]     The heat-dissipating element  117  contains a heat dissipating contact surface  1171  and multiple heat-dissipating fins  1172  that extended from the heat dissipating contact surface  1171 . On the heat dissipating contact surface  1171  there is also a convex surface  1173  of predetermined shape. The fixing stand  115  and the PCB  114  make connections on the heat dissipating contact surface  1171 , and the bump  1173  is exactly located at the space formed by the two stands  1152 , 1153 . This enables the location on the PCB  114  that supports the light emitting diode  111  to directly contact the bump  1173  on the heat dissipating contact surface  1171 .  
         [0038]     Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, that above disclosure should be construed as limited only by the metes and bounds of the appended claims.