Abstract:
A projector includes illumination optics for providing light beams, a light modulating apparatus for receiving and modulating the light beams provided by the illumination optics, a projection lens for projecting an image of the light beams received from the light modulating apparatus, a first adjusting device for adjusting a position of the illumination optics and adjusting an angle of incidence of the light beams emitted onto the light modulating apparatus, and a second adjusting device for adjusting a position of the projection lens in response to the adjustment of the position of the illumination optics for creating an offset of a position of the image projected by the projection lens.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of applicant&#39;s earlier application, Ser. No. 10/711,857, filed Oct. 10, 2004, the entirety of which is incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a projector, and more specifically, to a projector containing optical components with adjustable positions for adjusting an offset of projected images.  
         [0004]     2. Description of the Prior Art  
         [0005]     Image projectors, including digital projectors, are becoming increasingly popular for giving presentations or for home or office use. When setting up a projector for a specific location, the projector must be placed a suitable distance from a screen or other viewing surface. In addition, the projector must be positioned at a proper height and projection angle with respect to the horizontal. Since adjusting the projecting angle is such a common task, many projectors are equipped with adjustable legs positioned under one or more edges of the projector for raising or lowering the projector. By manually changing the height of the adjustable legs, images projected by the projector can be displayed on the proper area of the screen. However, the greater the angle in which the projector is raised, the more distorted the projected image will be. Distortion causes the projected images to appear as a trapezoid. In addition, the projected light intensity is not uniform for the entire image projected on the screen.  
         [0006]     Unfortunately, changing the height of the adjustable legs may involve interruption of the presentation since the projector may have to be lifted up to allow the adjustable legs to be adjusted. Moreover, the process of adjusting the viewing angle of the projected image may require the legs to be adjusted several times through trial and error. To correct this problem, a simpler way of adjusting an offset of projected images is needed.  
         [0007]     Adjustable lenses are available on the market for changing the focus of projected images. However, adjustable lenses can have the problem of emitting light at the wrong angle. Using the adjustable lenses in conjunction with an adjustable illumination optics system would improve the situation, but there are no adjustable illumination optics systems currently in use in projectors.  
       SUMMARY OF THE INVENTION  
       [0008]     It is therefore an objective of the claimed invention to provide a projector with movable optical components in order to solve the above-mentioned problems.  
         [0009]     According to the claimed invention, a projector includes illumination optics for providing light beams, a light modulating apparatus for receiving and modulating the light beams provided by the illumination optics, a projection lens for projecting an image of the light beams received from the light modulating apparatus, a first adjusting device for adjusting a position of the illumination optics and adjusting an angle of incidence of the light beams emitted onto the light modulating apparatus, and a second adjusting device for adjusting a position of the projection lens in response to the adjustment of the position of the illumination optics for creating an offset of a position of the image projected by the projection lens.  
         [0010]     It is an advantage of the claimed invention that the offset of the projected image can be adjusted without lifting up the projector and without adjusting the height of the legs of the projector. In addition, images projected from the projector will not be distorted and have the shape of a trapezoid. This also ensures that the projected light intensity is more uniform for the image projected on the screen. The first and second adjusting devices can be operated manually or electronically with a motor for quickly and conveniently adjusting the image offset. In this way, the proper viewing angle can be achieved without lifting up the main body of the projector and without needless adjustment of the legs of the projector through trial and error.  
         [0011]     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a diagram of a projector according to a first embodiment of the present invention.  
         [0013]      FIG. 2  is a diagram of a projector according to a second embodiment of the present invention.  
         [0014]      FIG. 3  is a diagram of a projector according to a third embodiment of the present invention.  
         [0015]      FIG. 4  is a diagram of a projector according to a fourth embodiment of the present invention.  
         [0016]      FIG. 5  is a diagram of the projector according to the first embodiment in which positions of the aspherical lens and the projection lens have been adjusted.  
         [0017]      FIG. 6  is a diagram of the projector according to the first embodiment in which positions of the concave mirror and the projection lens have been adjusted.  
         [0018]      FIG. 7  is a diagram of a projector according to a fifth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0019]     Please refer to  FIG. 1 .  FIG. 1  is a diagram of a projector  10  according to a first embodiment of the present invention. In the following disclosure, only components of the projector  10  that are relevant to the present invention are illustrated and described for clarity and simplicity. The projector  10  contains a lamp  12  for serving as a light source of the projector  10  and providing light beams  30 . The light beams  30  emitted by the lamp  12  pass through a light pipe  14 , which guides the light beams  30  to an aspherical lens  16 . The lamp  12 , the light pipe  14 , and the aspherical lens  16  are collectively referred to as illumination optics  15 . The illumination optics  15  can also optionally contain a concave mirror  18 . The aspherical lens  16  focuses the light beams  30  onto the concave mirror  18 . The concave mirror  18  reflects the light beams  30  to a digital mirror device (DMD)  20 , which modulates the light beams  30  and reflects the light beams  30  to a projection lens  22 . The projection lens  22  receives the light beams  30  from the DMD  20  and projects images from the projector  10  onto a viewing surface or a screen. The present invention projector  10  allows the position of two or more of the components of the projector  10  to be adjusted for changing an offset of the image projected by the projector  10 . For example, the illumination optics  15  can be adjusted along arrow  5 A while the projection lens  22  is adjusted along arrow  7 A. Adjusting the position of the illumination optics  15  compensates for lower projected light intensity as a result of adjusting the position of the projection lens  22 .  
         [0020]     Please refer to  FIG. 2 .  FIG. 2  is a diagram of a projector  40  according to a second embodiment of the present invention. Differing from the projector  10  shown in  FIG. 1 , the projector  40  contains a mirror  17  instead of the concave mirror  18 . The light beams  30  emitted by the lamp  12  pass through the light pipe  14 , which guides the light beams  30  to the aspherical lens  16 . The aspherical lens  16  focuses the light beams  30  onto the mirror  17 . The mirror  17  reflects the light beams  30  to the DMD  20 , which modulates the light beams  30  and reflects the light beams  30  to the projection lens  22 . For adjusting the offset of the projected image, the illumination optics  15  can be adjusted along arrow  5 B while the projection lens  22  is adjusted along arrow  7 B.  
         [0021]     Please refer to  FIG. 3 .  FIG. 3  is a diagram of a projector  42  according to a third embodiment of the present invention. Differing from the projector  40  shown in  FIG. 2 , the projector  42  contains a lens  19  used in conjunction with the mirror  17  instead of only using the mirror  17 . The light beams  30  emitted by the lamp  12  pass through the light pipe  14 , which guides the light beams  30  to the aspherical lens  16 . The aspherical lens  16  focuses the light beams  30  onto the mirror  17 . The mirror  17  reflects the light beams  30  to the lens  19 , which focuses the light onto the DMD  20 . The DMD  20  modulates the light beams  30  and reflects the light beams  30  to the projection lens  22 . For adjusting the offset of the projected image, the illumination optics  15  can be adjusted along arrow  5 C while the projection lens  22  is adjusted along arrow  7 C.  
         [0022]     Please refer to  FIG. 4 .  FIG. 4  is a diagram of a projector  44  according to a fourth embodiment of the present invention. Differing from the projector  10  shown in  FIG. 1 , the projector  44  does not contain the concave mirror  18  or any other mirror. Instead, light travels from the aspherical lens  16  to the DMD  20  directly. That is, the light beams  30  emitted by the lamp  12  pass through the light pipe  14 , which guides the light beams  30  to the aspherical lens  16 . The aspherical lens  16  focuses the light beams  30  onto the DMD  20 . The DMD  20  modulates the light beams  30  and reflects the light beams  30  to the projection lens  22 . For adjusting the offset of the projected image, the illumination optics  15  can be adjusted along arrow  5 D while the projection lens  22  is adjusted along arrow  7 D.  
         [0023]     Please refer to  FIG. 5 .  FIG. 5  is a diagram of the projector  10  according to the first embodiment in which positions of the aspherical lens  16  and the projection lens  22  have been adjusted. As compared to positions in  FIG. 1 , the position of the aspherical lens  16  has been moved downward along arrow A and the position of the projection lens  22  has been moved upward along arrow B. Due to these changes in position, projected light beams  32  are offset from the original position of the light beams  30 . An offset OFFI between the light beams  30  and the light beams  32  is illustrated in  FIG. 5 . By moving the position of the aspherical lens  16  downward along arrow A, the offset OFF 1  between the light beams  30  and the light beams  32  is created. Therefore, the projection lens  22  is also moved upward along arrow B so that the light beams  32  pass through a pupil of the projection lens  22 . Although the aspherical lens  16  and the projection lens  22  can be moved separately, they are preferably moved simultaneously by gears or other adjusting devices that can be operated manually or operated electronically by motors such as step motors or DC motors.  
         [0024]     Please refer to  FIG. 6 .  FIG. 6  is a diagram of the projector  10  according to the first embodiment in which positions of the concave mirror  18  and the projection lens  22  have been adjusted. As compared to positions in  FIG. 1 , the position of the concave mirror  18  has been moved downward along arrow C and the position of the projection lens  22  has been moved upward along arrow D. Due to these changes in position, projected light beams  34  are offset from the original position of the light beams  30 . An offset OFF 2  between the light beams  30  and the light beams  34  is illustrated in  FIG. 6 . By moving the position of the concave mirror  18  downward along arrow C, the offset OFF 2  between the light beams  30  and the light beams  34  is created. Therefore, the projection lens  22  is also moved upward along arrow D so that the light beams  34  pass through a pupil of the projection lens  22 . Although the concave mirror  18  and the projection lens  22  can be moved separately, they are preferably moved simultaneously using movements in proper proportion with each other. While only two components of the projector  10  need to be moved in order to create an offset of the projected images, more components can also be moved. For instance, the aspherical lens  16 , the concave mirror  18 , and the projection lens  22  can all be moved at the same time for adjusting the offset of the projected images. If a greater number of components have adjusted positions, then the displacement required for adjusting the position of each component can be lowered.  
         [0025]     The above has shown how components of the projector  10  of the first embodiment can be adjusted for creating an offset of the projected images. The projectors of the second, third, and fourth embodiments also have components that can be adjusted. For instance, the mirror  17  or the aspherical lens  16  of the projector  40  shown in  FIG. 2  can be moved in conjunction with the projection lens  22  for creating an offset. Likewise, a combination of one or more of the mirror  17 , the lens  19 , or the aspherical lens  16  of the projector  42  shown in  FIG. 3  can be moved in conjunction with the projection lens  22  for creating an offset. As for the projector  44  shown in  FIG. 4 , the aspherical lens  16  can be moved in conjunction with the projection lens  22  for creating an offset.  
         [0026]     Please refer to  FIG. 7 .  FIG. 7  is a diagram of a projector  50  according to a fifth embodiment of the present invention. The projector  50  contains different components than the projector  10  and also contains a plurality of gears  60 - 70  for adjusting the positions of the concave mirror  18  and he projection lens  22 . In  FIG. 7 , the projector  50  contains a folding mirror  51 for reflecting light beams  30  emitted by a lamp (not shown in  FIG. 7 ) to a concave mirror  18 . The use of the folding mirror  51 allows the projector  50  to be built with a compact shape for reducing the overall size of the projector  50 . The light beams  30  are reflected from the concave mirror  18  to the DMD  20 , and are then reflected to the pupil of the projection lens  22 . The aspherical lens  16  is not shown in  FIG. 7  for clarity, but may also be included in the projector  50 .  
         [0027]     The body of the projection lens  22  has adjusting legs  58  that rest against rigid members  52  of the housing of the projector  50 . The rigid members  52  keep the projection lens  22  in place while allowing the adjusting legs  58  to move up and down against the rigid members  52 . In this way, the projection lens  22  can move downward along arrow F or move up in the opposite direction. The downward and upward movement of the projection lens  22  is produced by the rotation of gear  70 , which moves a straight gear rack  56  attached to one of the adjusting legs  58  up and down. A main gear  60  is used for rotating a series of smaller gears. Although several gears are shown in  FIG. 7 , a smaller number or a larger number of gears may also be used with the present invention. In  FIG. 7 , the main gear  60  is shown as rotating clockwise. The main gear  60  rotates gear  62 , which rotates counter-clockwise. Gear  62  causes gear  66  to rotate in a clockwise direction, and in turn causes gear  68  to rotate in a counter-clockwise direction. Finally, the rotation of gear  68  causes gear  70  to rotate in a clockwise direction, and thereby causes the straight gear rack  56  to move upwards. At the same time, the rotation of gear  62  causes gear  64  to rotate in a clockwise direction. The rotation of gear  64  causes straight gear rack  54 , which is attached to the concave mirror  18 , to move downward along arrow E. Therefore, turning the main gear  60  adjusts the position of both the projection lens  22  and the concave mirror  18 . Additional gears may be used for adjusting the position of the folding mirror  51 as well.  
         [0028]     In summary, adjusting positions of the optical components of the present invention projector allows an image projected by the projector to be offset. Instead of manually adjusting the height of one leg of the projector using an adjustable leg, the positions of the optical components can be adjusted instead. Those skilled in the art will appreciate that any kind of adjusting device can be used for adjusting the positions of the projection lens  22 , the concave mirror  18 , and the folding mirror  51 . As was shown in  FIG. 5 , the position of the aspherical lens  16  can also be adjusted. A variety of adjustments to the optical components of the projector are possible so long as the light beams reach the pupil of the projection lens  22 .  
         [0029]     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.