Abstract:
An improved VGA connector that supports enhanced graphic performance by internally incorporating one or more functions of fusing, filtering, shielding, and the controlling of signal line impendances. The improved VGA connector is dimensionally interchangeable with many aspects of standard VGA connectors, and use standard pin-outs that mate with mating connectors. Integral DACs can be included to provide analog outputs.

Description:
FIELD OF THE INVENTION 
   The present invention relates to computer connectors. More specifically, embodiments of the present invention relate to VGA connectors that have integral electronic components. 
   BACKGROUND OF THE INVENTION 
   Almost all personal computers use the same type of 15 pin display connector. Because that connector was used in the original IBM VGA card it is often referred to simply as the VGA connector. Since the VGA connector is so widely used it acts as a standard that enables different graphic display electronics providers to provide equipment that mate with displays from different display providers. 
   While the VGA connector has been very successful over the years, it has several drawbacks that have become more important as displays and the computer systems that drive them have advanced. First, the VGA connector is not particularly well suited for high resolution video graphics systems. This is because the VGA connector does not provide well defined and controlled impedance characteristics. 
   Yet another problem with VGA connectors is that video graphics systems that use VGA connectors typically require extensive filtering of the signals passed via the VGA connector pins. While this is not in itself a problem, since different suppliers use filters that have different performance characteristics, the “standard” provided by the VGA connector is eroded by widely varying electronic interfaces. Even if two suppliers use supposedly identical filters, one supplier may use higher quality components that provide high quality filtering while the other supplier might use lesser quality components that provide relatively poor filtering. Another problem is that the VGA signals required shielding, but the standard VGA connector does not provide effective signal shielding. 
   Still another problem with using VGA connectors is that they do not support controlled signal paths. For example, two different display card manufacturers might use different signal paths to traverse the distance between the video driver, typically a digital to analog converter (DAC), and the VGA connector. 
   Uncontrolled variations in impedance characteristics, signal shielding, signal path lengths, and VGA signal filters can be highly damaging to the quality reputations of major device suppliers. For example, many different manufacturers might supply video graphics cards that use graphical processor devices supplied by another company. Indeed, that company&#39;s name is often prominently displayed in connection with the card. Since poor VGA connectors, filters, and uncontrolled signal path lengths can provide noticeably poor performance, the reputation of device suppliers can be harmed by factors related to VGA connectors. 
   Therefore, an improved VGA connector would be beneficial. Even more beneficial would be an improved VGA connector that provides signal shielding. Also beneficial would be an improved VGA connector that provides internal electronics, such as electronic filters and digital to analog converters. Such VGA connectors that also support controlled analog signal path lengths would also be beneficial. 
   SUMMARY OF THE INVENTION 
   The principles of the present invention provide for an improved VGA connector. Embodiments of the principles of the present invention provide for VGA connector having enhanced graphic performance by internally incorporating one or more functions of fusing, filtering, shielding, and controlling of signal line impendances. Embodiments of the inventive VGA connector are dimensionally interchangeable with many aspects of standard VGA connectors, and use standard pin-outs that mate with mating connectors. At least some embodiments include integral DACs to provide analog outputs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
       FIG. 1  is a perspective illustration of a VGA connector that is in accord with the principles of the present invention; 
       FIG. 2  is an exploded view of the VGA connector illustrated in  FIG. 1 ; 
       FIG. 3  is a schematic depiction of a filter assembly that is internal to the VGA connector illustrated in  FIGS. 1 and 2 ; 
       FIG. 4  is schematic depiction of a prior art DAC graphics driver and VGA connector on a circuit board; and 
       FIG. 5  is a schematic depiction of a VGA connector having an integral DAC driver on a board that feeds digital signals to the DAC. 
   

   To facilitate understanding, identical reference numerals have been used, wherever possible, to designate identical elements that are common to the figures. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The principles of the present invention provide for improved graphic performance using an inventive VGA connector having internal support for one or more fusing, filtering, shielding, and controlling impendances. While the inventive VGA connector is beneficial in many respects, it is in many respects dimensionally interchangeable with standard VGA connectors and pin-outs, and mates with mating connectors. At least some embodiments include integral DACs to provide analog outputs. 
   For convenience, the standard VGA pinouts are provided below. Because of the pin-outs are standardized, what follows does not discuss particular pins. Rather, what follows discusses pins and connections in relation to power, logic signals, and analog voltages.
     Pin 1 Red output   Pin 2 Green out   Pin 3 Blue out   Pin 4 Monitor ID 2 in   Pin 5 Ground   Pin 6 Red return   Pin 7 Green return   Pin 8 Blue return   Pin 9 no pin   Pin 10 Sync return   Pin 11 Monitor ID 0 in   Pin 12 Monitor ID 1 in   Pin 13 Horizontal Sync out   Pin 14 Vertical Sync out   Pin 15 reserved (monitor ID 3)   

   Some of the pins pass analog 0.7 voltages (Vp-p) at nominal 75 ohm loads, while others operate at TTL levels. 
     FIG. 1  illustrates a perspective view of a VGA connector  100  that is in accord with the principles of the present invention. The VGA connector  100  includes a pin-retaining molded assembly  102  that extends from a surrounding conductive shield. The assembly  102  is partially covered by and extends into a conductive shroud  104  that mates with the conductive shield  106 . The assembly  102  and its relation to the conductive shroud  104  is best shown in  FIG. 2 . The VGA connector includes pins  108  for mounting on a circuit board. The VGA connector  100  also includes screw threads  110  for receiving a mating male connector&#39;s retaining screws. The shield  106  and the shroud  104  provide electrostatic shielding and physical protection for the various components within the VGA connector  100 . It should be noted that the pattern of the pins  108 , the locations and dimensions of the screw threads, and the physical dimensions and locations of the assembly  102  and the shroud  104  are the same as similar structures found in “standard” VGA connectors. Thus, the VGA connector  100  will mate with standard VGA male connectors. 
     FIG. 2  is an exploded view of the VGA connector  100 . As shown, the shroud  104  includes holes  208  that align with apertures  210  in the shield  106 . The screw threads  110  are part of a forked body  212  and, when the VGA connector is assembled, align with the apertures  210  and the holes  208 . The forked body  212  extends through slots  214  of a pin holder  230  that retains the pins  108 . The forked body  212  is dimensioned and located to match similar features in standard VGA connectors. When mounted on a circuit board the forked body  212  aligns with circuit board mounting holes. 
   Referring now to  FIGS. 1 and 2 , extending into the assembly  102  are 15 female pins  220  that each has an elongated body that is bent at 90 degrees. The pins extend from the assembly  102  to a circuit board  250 . The circuit board  250  includes a plurality of electronic components that form electronic filters for the pins and, in some embodiments, include digital-to-analog converters (discussed subsequently). The circuit board  250  also connects to the pins  108 . While the foregoing has described a circuit board  250 , in practice any type of interconnect scheme can be used. 
   As previously noted, the VGA connector  100  is physically dimensioned in accord to the standard VGA connector such that it mates to a standard VGA male connector. However, the VGA connector  100  includes a non-standard circuit board  250 , elongated and bent female pins  220 , the protective shield  106 , and various electronic components that are discussed below. 
     FIG. 3  illustrates a schematic diagram of a filter assembly  300  that is mounted on the circuit board  250 . The purpose of the filter assembly  300  is to reduce electrical noise and ringing, and to provide controlled impedances for signals that are output from the female pins  220 . The filter assembly  300  is comprised of three types of filters. The first filter  310  filters the output power (5V). It includes an inductor and a capacitor that connect to 5 volts through a fuse  312 . The second type of filter  320  is used to filter logic signals. That filter is comprised of a small resistor in series with an inductor, and a capacitor to ground. That filter reduces ringing on the logic lines. The third type of filter  330  filters the red, green and blue outputs which drive the external monitor. Each of those outputs is typically produced by a digital to analog converter (DAC). The filters  330  are comprised of capacitive input pi-filter in parallel with a load resistor. Because of the relatively small size of the VGA connector  100 , the various electronic components are comprised of surface mounted devices. 
   While most, possibly all, applications will benefit by having filters within the VGA connector  100 , in some applications it may be beneficial to mount the digital-to-analog converters which produce the red, blue and green outputs within the VGA connector  100 . One reason to do this is to equalize and/or reduce the signal path lengths of the analog signals, and thus improve performance. For example,  FIG. 4  illustrates a generic prior art layout  400  for producing analog color signals. The prior art system  100  includes a prior art VGA connector  402  and a digital analog converter  404  that are both mounted on a graphics card  401 . The digital-to-analog converter  404  receives its digital input from a digital driver  406 . The digital-to-analog converter  404  sends its output on a line  408  that runs to the VGA connector  402 , and from there, to a video monitor. The length of the line  408  is not standardized. Furthermore, since three different digital-to-analog converters  404 , one for each color, are required, three different lengths  408  can exist on the same graphics card  401 . It is beneficial to reduce the length of the lines  408  and/or to equalize them. 
     FIG. 5  illustrates a graphics layout  500  that is in accord with the principles of the present invention. That layout  500  includes a printed circuit board  501  and a VGA connector  502 , which is very similar to the VGA connector  100  except the VGA connector  502  includes at least one (preferably all) digital-to-analog converters  404  on the circuit board  250 . The output of the digital-to-analog converter  404  is on a line  508 , which can be very short. Furthermore, the digital signals from the digital driver  406 , which are not particularly susceptible to noise, can be routed across the board  501  at the convenience of the circuit board layout engineer. 
   While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.