Patent Publication Number: US-2006012723-A1

Title: Optical adjusting apparatus

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The invention relates to an optical adjusting apparatus, and more particularly to an optical adjusting apparatus applied in a video and audio reproducing system.  
      2. Description of the Prior Art  
      Currently, because the focal length of a lens in a projection television is fixed (i.e. the focal length cannot be adjusted), the image size projected from the projection television is not adjustable. In other words, the conventional projection television doesn&#39;t have the function of adjusting the image size.  
      Referring to  FIG. 1 ,  FIG. 1  is a schematic diagram illustrating a conventional projection television  10  projecting an image  14 . As shown in  FIG. 1 , there is always unstable noise around the edge of the image  14  projected from the projection television  10 , so the size of the image  14  is usually enlarged to be bigger than the size of the screen  12 . Afterward, the screen  12  is capable of displaying a stable image. In general, the projection television always enlarges the image  14  with 2% to 7% times the original size of the image  14 , so as to effectively eliminate the noise around the edge of the image  14 . As shown in  FIG. 1 , the area of oblique line represents the unstable noise around the edge of the image  14  projected from the projection television  10 , wherein the unstable noise is eliminated by the screen  12 . The screen  12  effectively eliminates the unstable noise around the edge of the image  14 , so that the user can enjoy the stable image  14  through the screen  12 .  
      However, the method for eliminating the noise around the edge of the image  14  by enlarging the image  14  reduces the visible area of the image  14 . Although the image  14  is enlarged, the size of the screen  12  still maintains constant. Accordingly, the enlarged image  14  can only be displayed within the size of the screen  12 , so the visible area of the image  14  is reduced and the overall brightness is also reduced, consequently the sharpness of the image  14  is lowered and the quality of the image  14  becomes unclear.  
      Referring to  FIG. 2A  and  FIG. 2B , which are schematic diagrams illustrating the loss of the image brightness.  FIG. 2A  is a schematic diagram illustrating an image projected from a lens  20  of a projection television onto a screen  22 .  FIG. 2B  is a schematic diagram illustrating an enlarged image projected from a lens  20  of a projection television onto a screen  22 . As shown in  FIG. 2B , when the enlarged image is projected from the lens  20  onto the screen  22 , because the size of the enlarged image is larger than that of the screen  22 , some of the enlarged image is blocked and reflected by the screen  22 , and consequently the overall brightness is reduced and the sharpness of the image is lowered.  
      Therefore, one objective of the invention is to provide an optical adjusting apparatus for solving the above-mentioned problems.  
     SUMMARY OF THE INVENTION  
      An objective of the invention is to provide an optical adjusting apparatus, which is applied in a video and audio reproducing system, for the user to adjust the focal length of the lens group within the video and audio reproducing system according to his/her own requirement so as to adjust the size of the image displayed by the video and audio reproducing system.  
      Another objective of the invention is to provide an optical adjusting apparatus, which is applied in a video and audio reproducing system, for the user to adjust the image-forming focal point of the lens group within the video and audio reproducing system according to his/her own requirement so as to enhance the image fidelity of the video and audio reproducing system.  
      The invention discloses an optical adjusting apparatus in a video and audio reproducing system. The optical adjusting apparatus is used for adjusting the focal length of a lens group in the video and audio reproducing system. The lens group includes a first lens set and a second lens set. The optical adjusting apparatus includes a controller and a moving device. The controller is used for generating an adjusting signal. The moving device is connected to the controller and the lens group. According to the adjusting signal, the moving device is used for adjusting a position of the first lens set and a position of the second lens set, so as to adjust the focal length and the image-forming focal point of the lens group.  
      According to the invention, the optical adjusting apparatus applied in a video and audio reproducing system utilizes the moving device to adjust the focal length and the image-forming focal point of the lens group. Therefore, the user can adjust the image size at will so as to increase the visible area of the image, reduce the loss of the brightness, and eventually enhance the image sharpness.  
      The advantage and spirit of the invention can be understood by the following recitations together with the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE APPENDED DRAWINGS  
       FIG. 1  is a schematic diagram illustrating a conventional projection television projecting an image.  
       FIG. 2A  is a schematic diagram illustrating an image projected from a lens of a projection television onto a screen.  
       FIG. 2B  is a schematic diagram illustrating an enlarged image projected from a lens of a projection television onto a screen.  
       FIG. 3  is a system block diagram illustrating an optical adjusting apparatus according to a preferred embodiment of the invention.  
       FIG. 4  is a schematic diagram illustrating the optical adjusting apparatus shown in  FIG. 3 .  
       FIG. 5  is a schematic diagram illustrating the lens group of the optical adjusting apparatus shown in  FIG. 3 .  
       FIG. 6  is a schematic diagram illustrating an optical adjusting apparatus according to another preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to  FIG. 3  and  FIG. 4 ,  FIG. 3  is a system block diagram illustrating an optical adjusting apparatus  30  according to a preferred embodiment of the invention.  FIG. 4  is a schematic diagram illustrating the optical adjusting apparatus  30  shown in  FIG. 3 . According to the invention, the optical adjusting apparatus  30  applied in a video and audio reproducing system is used for adjusting the focal length and the image-forming focal point of a lens group  32  within the video and audio reproducing system. The lens group  32  includes a first lens set  34  and a second lens set  36 . The optical adjusting apparatus  30  includes a controller  38  and a moving device  40 .  
      The controller  38  is used for generating an adjusting signal. The moving device  40  is connected to the controller  38  and the lens group  32 . According to the adjusting signal, the moving device  40  is used for adjusting a position of the first lens set  34  and a position of the second lens set  36 , so as to adjust the focal length and the image-forming focal point of the lens group  32 .  
      Referring to  FIG. 4  and  FIG. 5 ,  FIG. 5  is a schematic diagram illustrating the lens group  32  of the optical adjusting apparatus  30  shown in  FIG. 3 . As shown in  FIG. 4  and  FIG. 5 , the lens group  32  includes a first gear  42  and a first cam  44 , wherein a first lens set  34  is fixed on the first cam  44 . The moving device  40  includes a first motor  46  connected to the first lens set  34 . The first gear  42  of the lens group  32  is connected to the first motor  46  and the first cam  44 . According to the adjusting signal, the first motor  46  rotates the first gear  42  to further move the first cam  44 . Afterward, the first lens set  34  will move together with the first cam  44 , so as to adjust the position of the first lens set  34 . Accordingly, the image size can be adjusted by adjusting the focal length of the lens group  32 .  
      The moving device  40  further includes a second motor  48  connected to the second lens set  36 . The lens group  32  further includes a second gear  50  and a second cam  52 , wherein a second lens set  36  is fixed on the second cam  52 . The second gear  50  is connected to the second motor  48  and the second cam  52 . According to the adjusting signal, the second motor  48  rotates the second gear  50  to further move the second cam  52 . Afterward, the second lens set  36  will move together with the second cam  52 , so as to adjust the position of the second lens set  36 . Accordingly, the image-forming focal point of the lens group  32  can be adjusted to enhance the image fidelity of the video and audio reproducing system.  
      According to the invention, the optical adjusting apparatus can control the first motor to move the first lens set by the moving device or control the second motor to move the second lens set by the moving device. The optical adjusting apparatus can also simultaneously control the first motor and the second motor to move the first lens set and the second lens set. Accordingly, the focal length and the image-forming focal point of the lens group can be adjusted.  
      In a preferred embodiment of the invention, the first motor and the second motor both are stepper motors with high stability and high precision. Therefore, since the invention utilizes the stepper motor to be the first motor and the second motor, the invention can precisely control the first motor and the second motor to move the first lens set and the second lens set. Because the first lens set and the second lens set both can be moved precisely, the focal length and the image-forming focal point of the lens group can be controlled precisely.  
      Referring to  FIG. 6 ,  FIG. 6  is a schematic diagram illustrating an optical adjusting apparatus  60  according to another preferred embodiment of the present invention. As shown in  FIG. 6 , the optical adjusting apparatus  60  includes a wireless receiver  62  connected to the controller  64 . The wireless receiver  62  is used for receiving a wireless signal and generating a triggering signal. According to the triggering signal, the controller  64  generates an adjusting signal. After receiving the adjusting signal, the moving device  66  adjusts the focal length of the lens group  68 . In another preferred embodiment, the wireless receiver is a signal receiver of a common remote control. When a user uses the remote control to generate a wireless signal, the signal receiver will generate a triggering signal and transmit the triggering signal to the controller. Afterward, according to the triggering signal, the controller generates the adjusting signal, and then, according to the adjusting signal, the motor rotates to further adjust the position of the lens set, so as to adjust the focal length and the image-forming focal point of the lens.  
      In a preferred embodiment, the video and audio reproducing system can be a projection television. The user can adjust the image size by changing the focal length of the lens group of the projection television. In another preferred embodiment, the video and audio reproducing system can be a projector. The user can also adjust the projected image size by adjusting the focal length of the lens.  
      According to the invention, the optical adjusting apparatus utilizes the controller to control the motor and further utilizes the gear connected to the motor to rotate the cam. Accordingly, the position of the lens fixed on the cam can be adjusted, and then the focal length of the lens group of the projection television can be also adjusted. Compared to the conventional projection television with fixed focal length, the user can adjust the focal length of the lens group to adjust the image size at will. The invention reduces the adjusted image size by adjusting the position of the lens, so as to increase the visible area of the image. Furthermore, because the image size is reduced, the loss of the brightness is also reduced. The reduced image is further adjusted by the second lens set so as to enhance the image fidelity. Therefore, the image displayed by the video and audio reproducing system will have better visible area, high brightness and high fidelity.  
      With the example and explanations above, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.