Patent Document

FIELD OF THE INVENTION 
       [0001]    The present invention relates to a light source of a projection device, and in particular to a projector that uses a laser as a light source. 
       BACKGROUND OF THE INVENTION 
       [0002]    Projectors have been widely used in a variety of applications, including commercial advertisements, product briefs, academic conferences, speeches, home cinema facility, and commercial/industrial conferences and other commercial/industrial applications. A conventional projector is operated with reflection of light, together with transparent sheets or slides, to project texts and images carried on the transparent sheets or the slides through an optic lens. 
         [0003]    With the development of digital technology, digital and powerful projection devices replace the conventional optic projectors to serve as a peripheral device that facilitates a display device to project texts and images on a projection display screen. Most of the currently available use a halogen lamp or a cold light as a projection light. 
         [0004]      FIG. 1  of the attached drawings shows an optic path diagram of a conventional projector. The conventional projector, generally designated at  100 , comprises a halogen lamp  11 , a lens  12 , and a liquid crystal panel  13 . In the operation of the projector  100 , the halogen lamp  11  generates a diffusible light beam L 1 , which transmits through the lens  12  and projects to the liquid crystal panel  13 . Thus, the projector  100  generates a specific image and projects the image onto a projection display screen  14  to be observed by an observer. 
         [0005]    It is noted that all the projection devices are operated with a projection light to perform normal projection function and conventionally, the projection light is provided by a halogen lamp or a cold light source. A halogen lamp features high lighting efficiency and low costs as compared to other projection light sources of similar power. However, the halogen lamp generates a great amount of heat, which may cause overheating of the projection device, and even causes fires on inflammable objects that are located nearby. Thus, some of the manufacturers are devoted to cooling solutions of the halogen lamp based projectors in order to overcome the overheating problem. The cooling solution, however, adds new problems of increasing requirement of space for installation. 
         [0006]    Further, in a projection device that uses a halogen lamp as light source, the light projected by the projection device is diffused in a circular form so that when an operator adjusts the size of a projection zone, additional facility, including image conversion means and/or light shielding means, must be used to do the adjustment. This causes certain inconvenience of operating the projector. 
         [0007]    In addition, compared to other projection lights, the halogen lamp also suffers large power consumption and high risk of malfunctioning and failure. Apparently, the service life of the projector is substantially reduced and economic operation is negatively affected. 
       SUMMARY OF THE INVENTION 
       [0008]    Thus, an objective of the present invention is to provide a projector that uses a laser source as a light source, wherein laser light is employed to serve as a projection light of the projector and a deflection reflector deflects a laser beam from the laser source to a liquid crystal panel to induce an image that is then projected to a screen. 
         [0009]    Another objective of the present invention is to provide a projector that employs a laser source, wherein a laser beam is used as a projection light and the characteristics of laser beam related to conversion/diffusion is used to efficient and effective adjust the size of a projection zone of the projector. 
         [0010]    To achieve the above-mentioned objectives, in accordance with the present invention, a projector comprises a laser source, a collimate lens, a deflection reflector, a deflection controller coupled to the deflection reflector, and a liquid display panel. When the projector is put into operation, the laser source generates a laser beam that is projected to the collimate lens. The collimate lens converts the laser beam from the laser source into a collimated laser beam. 
         [0011]    The collimated laser beam from the collimate lens is projected onto the deflection reflector, which, under the control of the deflection controller, is rotatable within a predetermined deflection angle range with a reference axis as a rotation center to deflect the collimated laser beam to the liquid crystal panel in a scanning manner. The collimated laser beam, after passing through a filter of the liquid crystal panel, induces a specific image on the liquid crystal panel, which is then projected to a projection display screen to allow an observer to see the image by means of visual persistence. 
         [0012]    In an embodiment of the present invention, a plurality of laser sources is employed to generate a plurality of laser beams, which are respectively projected toward a plurality of collimate lenses to convert the laser beams from the laser sources into collimated laser beams. The collimated laser beams are then processed by reflectors to eventually form a combined laser beam, which is deflected by the deflection reflector to project toward the liquid crystal panel. 
         [0013]    In an embodiment of the present invention, the laser beam that is deflected by the deflection reflector is guided toward a digital micro-reflector element to generate a specific image that is projected onto the projection display screen. 
         [0014]    Apparently, as compared to the conventional devices, the present invention uses a laser source as a projection light of the projector. This effectively overcomes the drawbacks of high temperature, high risk of malfunction, and reduced service life of the conventional projectors that use a halogen lamp as light source and also features the projector with high brightness, directivity, and monochromaticity. Also, the present invention allows for efficient and effective adjustment of size of projection zone. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, in which: 
           [0016]      FIG. 1  schematically shows optic path of diffusion light beam generated by a projection light source of a conventional projector; 
           [0017]      FIG. 2  schematically shows, in a side elevational view, optic path of a laser beam generated by a laser source of a projector in accordance with a first embodiment of the present invention; 
           [0018]      FIG. 3  schematically shows, in a top view, the optic path of the laser beam generated by the laser source of the projector in accordance with the first embodiment of the present invention; 
           [0019]      FIG. 4  schematically shows collimated-beam projection range and diffused-beam projection range of the laser beam generated by the laser source of the first embodiment of the present invention; 
           [0020]      FIG. 5  schematically shows deflection angle range provided by a deflection reflector of the projector of the first embodiment of the present invention; 
           [0021]      FIG. 6  schematically shows optic path of laser beams generated by laser sources of a projector in accordance with a second embodiment of the present invention; and 
           [0022]      FIG. 7  schematically shows optic path of a laser beam generated by a laser source of a projector in accordance with a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    With reference to the drawings and in particular to  FIGS. 2-5 , a projector constructed in accordance with the present invention, generally designated with reference numeral  200 , comprises a laser source  2 , a collimate lens  3 , a deflection reflector  4 , a deflection controller  41  coupled to the deflection reflector  4 , and a liquid crystal panel  5 . When the projector  200  is actuated, the laser source  2  emits a laser beam L 2 , which is projected in a predetermined projection direction. The laser beam L 2  has a longitudinal collimated-beam projection range A and a lateral diffused-beam projection range B. In the embodiment illustrated, the longitudinal collimated-beam projection range A of the laser beam L 2  is around 7 to 8 degrees, while the lateral diffused-beam projection range B is around 36 degrees for the laser beam L 2 . 
         [0024]    The longitudinal collimated-beam projection range A and the lateral diffused-beam projection range B of the laser beam L 2  can be varied in accordance with the requirements of the projector  200 . The laser source  2  is a white laser source in the embodiment illustrated, but can be of other colors in accordance with the applications of the projector  200 . 
         [0025]    The collimate lens  3  is arranged in the predetermined projection direction where the laser beam L 2  travels from the laser source  2  to convert the laser beam L 2  into a collimated laser beam L 2 ′, which is projected toward the deflection reflector  4 . 
         [0026]    The deflection reflector  4  is controlled by the deflection controller  41  and is rotatable, with a reference axis  42  as a rotation center, within a predetermined deflection angle range θ. The liquid display panel  5  is arranged adjacent to the deflection reflector  4  and is located in the predetermined deflection angle range θ of the collimated laser beam L 2 ′ projected from the deflection reflector  4 . The liquid display panel  5  has longitudinal and lateral dimensions that are covered by the longitudinal collimated-beam projection range A and the lateral diffused-beam projection range B of the laser beam L 2  emitted from the laser source  2 . 
         [0027]    When the collimated laser beam L 2 ′ is projected from the collimate lens  3  to the deflection reflector  4 , the collimated laser beam L 2 ′ is deflected by the deflection reflector  4 , within the predetermined deflection angle range θ, in a repeated scanning manner, to the liquid crystal panel  5 , and is filtered by a filter of the liquid crystal panel  5  to produce a specific image on the liquid crystal panel  5 , which image is thus projected to a display screen  6 , so that an observer can see the image projected from the projector  200  by means of visual persistence. 
         [0028]    As shown in  FIG. 6 , which shows a schematic view of optic path of a laser beam generated by laser sources in accordance with a second embodiment of the present invention, a projector in accordance with the present invention, designated with reference numeral  200   a , comprises three laser sources  2   a ,  2   b ,  2   c , three collimate lenses  3   a ,  3   b ,  3   c , three reflectors  7   a ,  7   b ,  7   c , a deflection reflector  4   a , a deflection controller  41   a  coupled between the deflection reflector  4   a  and a liquid crystal panel  5   a.    
         [0029]    The laser sources  2   a ,  2   b ,  2   c  generate laser beams L 3   a , L 3   b , L 3   c , respectively, which are projected in predetermined projection directions. The laser beams L 3   a , L 3   b , L 3   c  are of the same longitudinal collimated-beam projection range A and lateral diffused-beam projection range B as the laser beam L 2  generated from the laser source  2 . Thus, the laser beams L 3   a , L 3   b , L 3   c  have a longitudinal collimated-beam projection range A of around 7-8 degrees and a lateral diffused-beam projection range B of around 36 degrees. 
         [0030]    The longitudinal collimated-beam projection range A and the lateral diffused-beam projection beam B of the laser beams L 3   a , L 3   b , L 3   c  can be adjusted in accordance with requirements set for the projector  200   a . The laser source  2   a  can be a red laser source, the laser source  2   b  a green laser source, laser source  2   c  a blue laser source. The laser beams L 3   a , L 3   b , L 3   c  generated from the laser sources  2   a ,  2   b ,  2   c  can also be changed to other colors in accordance with different applications of the projector  200   a.    
         [0031]    The collimate lenses  3   a ,  3   b ,  3   c  are arranged in the predetermined projection directions of the laser beams L 3   a , L 3   b , L 3   c  from the laser sources  2   a ,  2   b ,  2   c  to respectively convert the laser beams L 3   a , L 3   b , L 3   c  into collimated laser beams L 3   a ′, L 3   b ′, L 3   c ′, which are then projected toward the reflectors  7   a ,  7   b ,  7   c , respectively. 
         [0032]    The reflector  7   a  is a total reflection reflector, which reflects the collimated red laser beam L 3   a ′ from the collimate lens  3   a  in a total reflection manner. The reflector  7   b  is a semi-reflection reflector, which reflects the collimated green laser beam L 3   b ′ from the collimate lens  3   b  in a semi-reflection manner and allows the collimated red laser beam L 3   a ′ that is previously subject to total reflection by the reflector  7   a  to transmit therethrough to travel along with the collimated green laser beam  73   b ′ that is subject to semi-reflection by the reflector  7   b.    
         [0033]    The reflector  7   c  is a semi-reflection reflector, which reflects the collimated blue laser beam L 3   c ′ from the collimate lens  3   c  in a semi-reflection manner and allows the collimated red laser beam L 3   a ′ that is previously subject to total reflection by the reflector  7   a  and the collimated green laser beam L 3   b ′ that is previously subject to total reflection by the reflector  7   b  to transmit therethrough to combine with the collimated blue laser beam  73   c ′ that is subject to semi-reflection by the reflector  7   c , thereby forming a combined white laser beam L 3 , which is projected toward the deflection reflector  4   a.    
         [0034]    The deflection reflector  4   a  is controlled by the deflection controller  41   a  and is rotatable, with a reference axis  42   a  as a rotation center, within a predetermined deflection angle range θ′. The liquid display panel  5   a  is arranged adjacent to the deflection reflector  4   a  and is located in the predetermined deflection angle range θ′ of the collimated laser beam L 3  projected from the deflection reflector  4   a . The liquid display panel  5   a  has longitudinal and lateral dimensions that are covered by the longitudinal collimated-beam projection range A and the lateral diffused-beam projection range B of the laser beams L 3   a , L 3   b , L 3   c  emitted from the laser sources  2   a ,  2   b ,  2   c.    
         [0035]    When the combined white laser beam L 3  that is formed by the light components from the reflectors  7   a ,  7   b ,  7   c  is projected toward the deflection reflector  4   a , the combined laser beam L 3  is deflected by the deflection reflector  4   a , within the predetermined deflection angle range θ′, in a repeated scanning manner, to the liquid crystal panel  5   a , and is filtered by a filter of the liquid crystal panel  5   a  to produce a specific image on the liquid crystal panel  5   a , which image is thus projected to a display screen  6   a , so that an observer can see the image projected from the projector  200   a  by means of visual persistence. 
         [0036]    As shown in  FIG. 7 , which shows a schematic view of optic path of a laser beam generated by a laser source in accordance with a third embodiment of the present invention, a projector in accordance with the present invention, generally designated with reference numeral  200   b , comprises a laser source  2   d , a collimate lens  3   d , a deflection reflector  4   b , a deflection controller  41   b  coupled to the deflection reflector  4   b , and a digital micro-reflector element  8 . 
         [0037]    When the projector  200   b  is actuated, the laser source  2   d  emits a laser beam L 4 , which is projected in a predetermined projection direction. The laser beam L 4  has the same longitudinal collimated-beam projection range A and lateral diffused-beam projection range B as the laser beam L 2  generated from the laser source  2 . Thus, the longitudinal collimated-beam projection range A of the laser beam L 4  is around 7 to 8 degrees, while the lateral diffused-beam projection range B of the laser beam L 4  is around 36 degrees. 
         [0038]    The longitudinal collimated-beam projection range A and the lateral diffused-beam projection range B of the laser beam L 4  can be adjusted in accordance with the requirements set for the projector  200   b . The laser source  2   d  is a white laser source in the embodiment illustrated, but can be of other colors in accordance with the applications of the projector  200   b.    
         [0039]    The collimate lens  3   d  is arranged in the predetermined projection direction where the laser beam L 4  travels from the laser source  2  to convert the laser beam L 4  into a collimated laser beam L 4 ′, which is projected toward the deflection reflector  4   b.    
         [0040]    The deflection reflector  4   b  is controlled by the deflection controller  41   b  and is rotatable, with a reference axis  42   b  as a rotation center, within a predetermined deflection angle range θ″. The digital micro-reflector element  8  is arranged adjacent to the deflection reflector  4   b  and is located in the predetermined deflection angle range θ″ of the collimated laser beam L 4 ′ projected from the deflection reflector  4   b . The digital micro-reflector element  8  has longitudinal and lateral dimensions that are covered by the collimated-beam projection range A and the diffused-beam projection range B of the laser beam L 4  emitted from the laser source  2   d.    
         [0041]    When the collimated laser beam L 4 ′ is projected from the collimate lens  3   d  to the deflection reflector  4   b , the collimated laser beam L 4 ′ is deflected by the deflection reflector  4   b , within the predetermined deflection angle range θ″, in a repeated scanning manner, to the digital micro-reflector element  8  so as to produce a specific image by means of the digital micro-reflector element  8 , which image is projected onto a display screen  6   b , whereby an observer can see the image projected from the projector  200   b  by means of visual persistence. 
         [0042]    In the practical applications of the projectors  200 ,  200   a ,  200   b , the laser sources  2 ,  2   a ,  2   b ,  2   c ,  2   d  can be ordinary semiconductor laser or carbon dioxide laser. 
         [0043]    Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.

Technology Category: 3