Abstract:
The present invention aims to provide projectors for use in a multi-display system which allows images having arbitrary formats to be easily displayed in a variety of display patterns. To achieve this object, the projector in accordance with the present invention have the input pattern memory storing input format parameters and display pattern memory storing display parameters. The source images are processed based on the input format parameters and the display parameters, whereby the source images having different formats are displayed in a variety of display patterns.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a multi-display system, and more particularly to projectors constituting the multi-display system. 
   2. Description of the Related Art 
   A multi-display projector constitutes one screen by arranging a plurality of rear-projection-type projector units in both vertical and horizontal direction, and is widely used as a large screen display. In recent years, multi-display projectors are used to display the images generated by personal computers (PCs) for purpose of presentations. However, conventional multi-display projectors mainly deal with NTSC signals or high-definition television signals, while the image signals generated by PCs have various kinds of formats in terms of pixels per line and lines per frame. Therefor, it has been difficult for conventional multi-display projectors to display the image having different format. 
   It is therefor, a primary object of the invention to provide a multi-display projector that is capable of processing and displaying the images having different formats. 
   SUMMARY OF THE INVENTION 
   This object is achieved in accordance with one aspect of the present invention, a multi-display projector, comprises the input pattern memory storing input format parameters and display pattern memory storing display parameters. The input format parameters specify the number of active pixels, the number of active lines, the initial active pixel, and the active initial line of input image signals, and the display parameters designate a region of an image to be displayed. Source images are processed based on the input format parameters and the display parameters, whereby the source images having different formats are displayed in a variety of display patterns. 
   The above and other objects, and features of the present invention will be clear from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram showing the overall configuration of a multi-display projector in accordance with one embodiment of the present invention; 
       FIG. 2  is a block diagram showing the configuration of a multi-display projector unit in accordance with the one embodiment of the present invention; 
       FIG. 3  is a conceptual diagram illustrating input format parameters; 
       FIG. 4  is showing examples of input format parameters; 
       FIG. 5  is a conceptual diagram showing an active image stored in the frame memory; 
       FIG. 6  is a conceptual diagram illustrating display parameters; 
       FIG. 7  is showing an example of display parameters; 
       FIGS. 8A and 8B  is showing an example of a display pattern. 
       FIG. 9  is showing an example of output parameters; 
       FIG. 10  is a conceptual diagram showing the horizontal offset and the vertical offset; 
       FIG. 11  is a flowchart showing the operation of the projector unit in accordance with the one embodiment of the present invention; 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows the overall configuration of a multi-display system in accordance with an embodiment of the present invention. The multi-display system shown in  FIG. 3  is constituted of four projector units A, B, C and D indicated by reference numeral  200 . Controller  201  controls each of these projector units. 
     FIG. 2  shows the configuration of each of the projector units shown in FIG.  3 . The input format detector  1  detects input format parameters which specify the number of total dots, the number of total lines, the number of active pixels, the number of active lines, the initial active pixel, and the initial active line of the input image.  FIG. 3  is the conceptual diagram illustrating these input format parameters specifying the number of total dots, the number of total lines, the number of active pixels, the number of active lines, the initial active pixel, and the initial active line of the input image. The detected input format parameters are stored in the input format memory  90 .  FIG. 4  shows the example of the input format parameters. When n kinds of image signals are inputted to the projector unit, n groups of format parameters are stored in the input format memory  90 . “INPUT MEMORY NUMBER” illustrated in  FIG. 6  indicates the memory area where the groups of input format parameters are stored. Although not shown in the  FIG. 4 , the input format memory  90  stores other input format parameters such as FAIN adjustment values, clamp information, mask information of PLL, etc. to set up A/D converter  3 . The input format memory  90  also stores other input format parameters for video signals to set up the line doubler  4 . 
   As shown in the  FIG. 4 , the input format detector  1  outputs the RGB analog signal to the A/D converter  3 , video signal (NTSC signals and PAL signals) to the line doubler  4 , and digital image signal to the selector  5 . The A/D converter  3  converts the input RGB analog signals to digital image signals and output them to the selector  5 . The line doubler  4  converts the NTSC signals from interlace to non-interlace digital image signals and output them to selector  5 . The selector  5  receives digital image signals from the A/D converter  3 , the line doubler  4 , and the input format detector  1 . The selector  5  outputs selected image signals to the frame memory  6 . 
   Here, it is essential that the input format parameters stored in the input format memory  90  must include at least the number of active pixels, the number of active lines, the initial active pixel, and the initial active line of the input image. These parameters are necessary to writ active-image signals to the frame memory  6 . 
   The frame memory  6  stores the active-image extracted from whole image signals. Based on the input format parameters stored in the input format memory  90 , the frame memory controller  90  controls the timing of writing the image signals to the frame memory  6 , so that the active-image is stored in memory  6 . The frame memory  6  has enough memory to store such signals as high-definition television signals having high resolution. For example, the frame memory  6  must be capable of storing image signals represented with 1920 dots×1080 lines (the number of active pixels and the number of active lines of high-definition television signals) to display high-definition television signals. In this case, as conceptually illustrated in  FIG. 5 , the frame memory  6  stores image signals from the upper left corner in memory address  0 . 
   Based on the input format parameters stored in the input format memory  90 , the display region calculator  2  calculates the display parameters which designate the region of the segment-image, a portion of the active image to be displayed.  FIG. 6  is the conceptual diagram illustrating the display parameters. The display parameters include the number of segment-image pixels, the number of segment-image lines, the initial segment-image pixel, and the initial segment-image line. These display parameters are stored in the display pattern memory  100 .  FIG. 7  shows an example of display parameters. As shown in  FIG. 7  the display pattern memory  100  stores other parameters, the horizontal display-image size, the vertical display-image size, and the horizontal offset, and the vertical offset. “INPUT MEMORY NUMBER”, shown in  FIG. 7 , indicates the memory area where the input format parameters of the image signals to be processed with each set of the display parameters are stored. The horizontal offset and the vertical offset are variable parameters for shifting a image displayed on the screen in the horizontal direction and the vertical direction (Details of the horizontal position offset and the vertical position offset will be described later). 
   The display parameters provide various patterns of displaying images in the multi-display screens as shown in  FIGS. 8A and 8B .  FIG. 8A  is an example of the display pattern produced by the display parameters stored in the “DISPLAY MEMORY  1 ” illustrated in FIG.  7 . These display parameters are used to process the active-image stored in frame memory  6  into the image displayed in one of the projector units shown in FIG.  8 A.  FIG. 8B  is another example of the display pattern produced by the display parameters stored in the “DISPLAY MEMORY  2 ” illustrated in FIG.  7 . These display parameters are used to process the active-image stored in frame memory  6  into the image displayed in the projector units arranged in lower right shown in FIG.  8 B. These display parameters are prepared for each of the input format to accommodate with the image signals having different format. 
   Each image displayed by projector units corresponds to the segment-image extracted from the active-image shown in FIG.  6 . The image processor  7  extracts the segment-image signals and processes them. The image processor  7  enlarges or reduces the segment-image to appropriate size. The image processor controller  10  controls the image process mentioned above based on the display parameters. 
   The images processed by the image processor  7  are displayed by display  8  in accordance with the output format parameters stored in the output format memory  110 .  FIG. 9  shows an example of output parameters stored in the output pattern memory  110 . The initial output pixel and the initial output line designate the position where the image is displayed on the screen, which means the image displayed on the screen shifts by changing these parameters. The values of the initial output pixel and the initial output line are given by adding the horizontal offset and the vertical offset to their initial values. The horizontal offset and the vertical offset are variable parameters for shifting a display image from the initial position. Ordinarily, both of the horizontal offset and the vertical are 0, which means that the image is displayed in the predetermined position. However, when the deviation between optical system and the screen occurs, the displayed image shifts from the predetermined position as shown in FIG.  10 . Therefor, it is necessary to shift the initial output pixel and the initial output line to display the image in the right position. In case the image shifts from the initial position, display adjustment signals are inputted to the display pattern memory  10 , as shown in FIG.  2 . The values of the horizontal offset and the vertical offset are changed by the display adjustment signals. Accordingly, the value of the initial output pixel and the initial output line stored in the output format memory  110  are rewritten, and the position where the image is displayed is corrected. 
     FIG. 11  is the flowchart showing the operation of the projector unit shown in FIG.  2 . The input format detector detects the input format parameters of the input image signals (St 1 ). The input format parameters corresponding to the input signals are read out from the input format memory  90  (St 2 ), and the display parameters are read out from the display pattern memory  100  (St 3 ). Based on these parameters the display operation starts (St 7 ). If corresponding display parameters were not stored in the display pattern memory  100 , the display region calculator  2  calculates them. The calculated display parameters are written into the display pattern memory  100  (St 4 ), and then the display process starts (St 7 ). If the input format parameters corresponding to the input image signals were not stored in the input format memory  90 , the input format detector  1  detects them. The detected input format parameters are written into the input format memory  90  (St 5 ). The display region calculator  2  calculates display parameters corresponding to the display patterns. The calculated display parameters are written into the display pattern memory  100  (St 6 ), and the display process starts (St 7 ). 
   As described above, the projector units have the input format memory  90  storing the input format parameters which specifies the number of active pixels, the number of active lines, the initial active pixel, and the initial active line. These projector units also have the display pattern memory  100  storing display parameters which specifies the initial pixel, the initial line of the segment-image, the number of segment-image pixels, and the number of segment-image lines. Therefore, the source images having different formats are displayed in a variety of display patterns. 
   The input format parameters and the display parameters are separately stored in the input format memory  90  and the display pattern memory  100  to prevent the redundancy of the data storing. 
   The frame memory  6  stores the active-image from which the segment image is extracted based on the display parameters. This configuration enables quick change of the display patterns, for example, the ones shown in FIG.  8 A and FIG.  8 B. 
   Moreover, the display parameters include variable parameters, the horizontal offset and the vertical offset, which designate the amounts of displacement of the display position in both horizontal and vertical direction. Therefore, when the optical system deviates and the image displayed on the screen shifts from the initial position, the displaying position of the image is easily corrected by rewriting the horizontal offset and/or the vertical offset. 
   While the present invention is described with the reference considered to be the preferred embodiments, it is to be understood that various changes and modifications is possible without departing from the scope of as set forth in the claims appended hereto.