Abstract:
Systems and methods for modifying an intensity of a CRT stroke signal provided to a digital display displaying a stroke image are provided. One apparatus includes a velocity module for determining a vector velocity of the stroke image and an encoder for modifying the intensity of the stroke signal based on the vector velocity. A system includes a deflection input from multiple axes, a multiplexer for outputting the stroke signal, and a velocity intensity module (VIM). The VIM is configured to receive the stoke signal, determine a vector velocity of the stroke image based on the deflection inputs, and modify the stroke signal intensity based on the vector velocity. One method includes receiving first and second deflection inputs for the stroke image, determining a vector velocity for the stroke image based on the first and second deflection inputs, and modifying the stroke signal intensity based on the vector velocity.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to displays, and more particularly relates to systems and methods for modifying an intensity of a cathode ray tube stroke signal provided to a digital display. 
       BACKGROUND OF THE INVENTION 
       [0002]    Conversion of analog stroke deflection-based video for a cathode ray tube (CRT) display into a digitized format for display creates differences in appearance. The CRT-based display utilizes a combination of video intensity and deflection rate or electron beam velocity to provide differences in presentation intensity of displayed data. Specifically, the faster the electron beam in the CRT display is deflected or moving, the lower the luminance of the line being drawn and vice versa. Conventional digitized stroke display conversions do not take this fact into consideration when providing the stroke signal to the digital display. As a result, some data being displayed on the digital display may include a higher or lower level of luminance than intended for a CRT display. 
         [0003]    Accordingly, it is desirable to systems and methods for modifying an intensity of a CRT stroke signal intended for an electron beam provided to a CRT display, when applied to a digital display, to control the level of luminance of the data being displayed. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    Various embodiments provide an apparatus for modifying an intensity of a cathode ray tube stroke signal provided to a digital display displaying a stroke image. One apparatus comprises a velocity circuit configured to be coupled to the digital display and configured to determine a vector velocity of the stroke image. The apparatus further comprises an encoder circuit coupled to the velocity module and configured to modify the intensity of the stroke signal based on the vector velocity. 
         [0005]    Systems for modifying an intensity of a cathode ray tube stroke signal provided to a digital display displaying a stroke image are also provided. One system comprises a first deflection input from a first plane, a second deflection input from a second plane, a multiplexer (MUX) configured to output the stroke signal, and a velocity intensity module (VIM) coupled to the first deflection input, the second deflection input, and the MUX. The VIM is configured to receive the stoke signal, determine a vector velocity of the stroke image based on the first and second deflection inputs, and modify the intensity of the stroke signal based on the vector velocity. 
         [0006]    Also provided are methods for modifying an intensity of a cathode ray tube stroke signal provided to a digital display displaying a stroke image. One method comprises the steps of receiving a first deflection input and a second deflection input for the stroke image, determining a vector velocity of the stroke image based on the first and second deflection inputs, and modifying the intensity of the stroke signal based on the vector velocity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and 
           [0008]      FIG. 1  is a block diagram of one embodiment of a system for modifying an intensity of a cathode ray tube stroke signal provided to a digital display for displaying a stroke image; and 
           [0009]      FIG. 2  is a block diagram of one embodiment of a velocity intensity module included in the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention. 
         [0011]    Various embodiments of the invention provide systems and methods for modifying an intensity of a cathode ray tube (CRT) stroke signal provided to a digital display displaying a stroke image. Specifically, the systems and methods modify the intensity of the CRT stroke signal based on the vector velocity of the stroke image. 
         [0012]    Turning now to the figures,  FIG. 1  is a block diagram of one embodiment of a system  100  for modifying an intensity of a cathode ray tube stroke signal  105  provided to a digital display  110 . System  100 , at least in the embodiment illustrated in  FIG. 1 , comprises an X-axis deflection input  113 , a Y-axis deflection input  117 , a position addressing module (PAM)  120  coupled to X-axis deflection input  113  and Y-axis deflection input  117 , and a velocity intensity module (VIM)  130  coupled to X-axis deflection input  113  and Y-axis deflection input  117 . System  100  further comprises a multiplexer (MUX)  140  coupled to a raster/stroke control input  150  that alternates between selecting raster video signals  165  and stroke signals  105 , and coupled to a video intensity input  145  providing the intensity for the raster video signals  165  and the stroke signals  105 . Furthermore, system  100  comprises a stroke image memory  155  coupled to PAM  120  and VIM  130 , a raster video image memory  160  coupled to MUX  140 , a graphics processor  170  coupled to stroke image memory  155  and raster video image memory  160 , and digital display  110  coupled to graphics processor  170 , wherein digital display  110  may be any digital display known in the art or developed in the future. 
         [0013]    As discussed above, the luminance of the line being drawn in a CRT display is dependent on the vector velocity at which the electron beam is being deflected (or moving) and the value of the video intensity input. That is, the faster the electron beam is deflected, the lower the luminance of the line that is being drawn on the CRT display, and vice versa. The vector velocity of the electron beam can be determined using the change in position (i.e., the X-axis deflection and the Y-axis deflection) of the electron beam over time. With this in mind, the present invention uses signals for displaying a stroke image on digital display  110  to emulate the X-axis deflection input and the Y-axis deflection input of an electron beam in a CRT display. In other words, the address and data signals used to display the stroke image on digital display  110  emulate the X-deflection input and the Y-axis input in a PAM of a CRT display. 
         [0014]    PAM  120  may be any system, device, hardware (including software), or combinations thereof capable of determining the position of the stroke image being displayed on digital display  110 . In one embodiment, PAM  120  is configured to determine the position of the stroke image based on data received from X-axis deflection input  113  and Y-axis deflection input  117 . That is, PAM  120  is configured to determine the X and Y coordinates of the stroke image based on the data related to the X-plane from X-axis deflection input  113  and the data related to the Y-plane from Y-axis deflection input  117 . Furthermore, PAM  120  is configured to calculate the position of the stroke image based on the X and Y coordinates, and generate a signal  123  and a signal  127  indicating the X-coordinate and the Y-coordinate, respectively. The data related to the X-plane from X-axis deflection input  113  and the data related to the Y-plane from Y-axis deflection input  117  is also provided to VIM  130 . 
         [0015]    VIM  130  may be any system, device, hardware (including software), or combinations thereof capable of modifying the intensity of a CRT stroke signal. In one embodiment, VIM  130  is configured to modify (e.g., attenuate or amplify) the intensity of stroke signal  105  supplied from MUX  140  to generate modified stroke signal  107  based on the vector velocity of the stroke image being displayed on digital display  110 . Specifically, VIM  130  is configured to receive X-axis deflection input  113  and Y-axis deflection input  117 , determine the vector velocity of the stroke image based on X-axis deflection input  113  and Y-axis deflection input  117 , and attenuate or amplify stroke signal  105  based on the determined vector velocity. Specifically, once the vector velocity of the stroke image  105  is determined by VIM  130 , a modifying velocity component is added to stroke signal  105  to generate modified stroke signal  107  so that the desired luminance of the stroke image being displayed on digital display  110  may be obtained. In other words, modified stroke signal  107  includes data emulating the vector velocity of a CRT electron beam based on X-axis deflection input  113 , Y-axis deflection input  117 , and the video intensity input  145 , so that the stroke image being displayed on digital display  110  includes the desired level of luminance. 
         [0016]      FIG. 2  is a block diagram of one exemplary embodiment of VIM  130 . At least in the illustrated embodiment, VIM  130  comprises a difference circuit  1310  coupled to X-axis deflection input  113 , a difference circuit  1320  coupled to Y-axis deflection input  117 , a multiplier circuit  1330  coupled to difference circuit  1310 , a multiplier circuit  1340  coupled to difference circuit  1320 , an adder circuit coupled to multiplier circuits  1330  and  1340 , an encoder circuit  1360  coupled to adder circuit  1350 , and a multiplier circuit  1370  coupled to encoder circuit  1360  and configured to receive stroke signal  105  from MUX  140  (see  FIG. 1 ). 
         [0017]    Difference circuit  1310  comprises a memory  1312 , a memory  1314 , and a subtractor circuit  1316  coupled to memory  1312  and  1314 . Memory  1312  is configured to receive and, at least temporarily, store a first X-coordinate for the stroke image at time T 1 , and memory  1314  is configured to receive and, at least temporarily, store a second X-coordinate for the stroke image at time T 2 , which is subsequent to time T 1 . Subtractor circuit  1316  is configured to receive the first and second X-coordinates, and subtract the first X-coordinate from the second X-coordinate to determine an X-value representing the change in position of the stroke image in an X-axis. 
         [0018]    Difference circuit  1320  comprises a memory  1322 , a memory  1324 , and a subtractor circuit  1326  coupled to memory  1322  and  1324 . Memory  1322  is configured to receive and, at least temporarily, store a first Y-coordinate for the stroke image at time T 1 , and memory  1324  is configured to receive and, at least temporarily, store a second Y-coordinate for the stroke image at time T 2 . Subtractor circuit  1326  is configured to receive the first and second Y-coordinates, and subtract the first Y-coordinate from the second Y-coordinate to determine a Y-value representing the change in position of the stroke image in a Y-axis. The X-value and the Y-value are then transmitted to multiplier circuits  1330  and  1340 , respectively. 
         [0019]    Multiplier circuit  1330  is configured to square the X-value (i.e., (X-value) 2 ) determined by difference circuit  1310 . Similarly, multiplier circuit  1340  is configured to square the Y-value (i.e., (Y-value) 2 ) determined by difference circuit  1320 . The squared X-value and the squared Y-value are then transmitted to adder circuit  1350 . 
         [0020]    Adder circuit  1350  is configured to add the squared X-value and the squared Y-value to generate an XY-value representing the vector velocity of the stroke image. The XY-value is then transmitted to encoder circuit  1360 . 
         [0021]    Encoder circuit  1360  is configured to compare the XY-value to a predetermined level of luminescence for the stroke image to be displayed and generate a coefficient that attenuates or amplifies stroke signal  105  so that modified stroke signal  107  includes a coefficient that will produce the predetermined level of luminescence for the stroke image to be displayed on digital display  110 . In one embodiment, the XY-value itself is the coefficient. In another embodiment, encoder circuit  1360  includes a look-up table and is configured to generate the coefficient by matching the XY-value to a coefficient in the look-up table that corresponds to the XY-value. In this embodiment, each coefficient includes values less than, equal to, or greater than one (1). That is, the coefficient is greater than 1 (which emulates decreasing the velocity of an electron beam) if the stroke image is moving too slowly, the coefficient is equal to 1 if the stroke image is moving at the proper velocity, and the coefficient is less than 1 (which emulates increasing the velocity of an electron beam) if the stroke image is moving too fast. The coefficient is then transmitted to multiplier  1370 . 
         [0022]    Multiplier  1370  is configured to receive stroke signal  105  and multiply stroke signal  105  by the coefficient received from encoder circuit  1360  to generate modified stroke signal  107 . That is, modified stroke signal  107  increases or decreases the level of luminance of the stroke image to be displayed on digital display  110 . Alternatively, modified stroke signal  107  would have the effect of increasing or decreasing the vector velocity of an electron beam in a CRT display. Modified stroke signal  107  is then transmitted to stroke image memory  155  (see  FIG. 1 ). 
         [0023]    With reference again to  FIG. 1 , stroke image memory  155  is configured to receive and store modified stroke signal  107  in locations determined by signals  123  and  127 , which is then available for use by graphics processor  170  (discussed below). Similarly, raster video image memory  160  is configured to receive a raster video signal  165  from MUX  140  based on its corresponding raster/stroke control signal  150 . 
         [0024]    MUX  140  is coupled to a raster/stroke control input  150  configured to alternate between providing stroke signal  105  and raster video signal  165  to MUX  140 . MUX  140  is further coupled to a video intensity signal  145  that provides the intensity for stroke signal  105  or the intensity for raster video signal  165 . Furthermore, MUX  140  is configured to discriminate between stroke signals  105  and raster video signals  165 , and transmit each stroke signal  105  along with its corresponding video intensity signal  145  to VIM  130  and transmit each raster video signal  165  along with its corresponding video intensity signal  145  to raster video image memory  160 . 
         [0025]    Raster video image memory  160  is configured to receive and store raster video signal  165  and its corresponding video intensity signal  145 . As such, raster video signal  165  and its corresponding video intensity signal  145  are made available to graphics processor  170  via raster video image memory  160 . 
         [0026]    Graphics processor  170  may be any graphics processor known in the art or developed in the future. Graphics processor  170  is configured to receive the content of modified stroke signal  107  from stroke image memory  155 , and raster video signal  165  from raster video image memory  160 , and combine the corresponding respective video intensity signals  145  to digital display  110  in any manner known in the art that is capable of rendering stroke and raster images on digital display  110 . 
         [0027]    While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.