Patent Application
20070028281
This invention relates generally to computer or media systems having a source unit coupled to a display device by a video cable. More specifically, the invention relates to techniques for providing power to the source unit in such systems.
In personal computer systems as well as in entertainment systems, it is standard practice to couple a video source unit to a display device by means of at least one cable. For example, it is common to couple the main unit of a personal computer or the media box of an entertainment system to a monitor or television-style display screen by means of a Digital Visual Interface (“DVI”) cable.
In these and other similar systems, both the video source unit and the display device must have a power supply. Consequently, the weight, the heat generation characteristics and the expense of a power supply must be accommodated in both the source unit and the display device. Moreover, both of the power supplies require an a/c power cord and therefore contribute to what has already become a cable-management challenge in such systems.
The DVI standard specifies that, in a conventional DVI system, a personal computer drives +5V to a monitor over pin 14, and the personal computer couples its hot plug detect sensing logic to pin 16. In such a conventional system, the monitor uses the +5V it receives from the personal computer on pin 14 to raise hot plug detect pin 16 to +5V. By way of contrast,
In system 100, a source unit 102 and a display device 104 are coupled together by a standard DVI-compliant video cable 106 using DVI-compliant connectors 118, 120. Source unit 102 is configured to receive its main power supply from pin 14 of cable 106. For example, a video source 112 within source unit 102 may be configured to receive its main power supply from pin 14 as indicated at 108, or other electronics 114 may be so configured as indicated at 110, or both. But a DDC/CI (“Display Data Channel Command Interface”) communications section 116 of source unit 102 is configured to operate using +5V supplied on pin 16 of cable 106 instead of by any power supply internal to source unit 102.
Display device 104 includes a switch 122 for connecting pin 14 of connector 120 either to a power supply 126 or not. Display device 104 also includes a video consumer 128, DDC/CI communications logic 130 and control logic 132. Power supply 126 is configured to drive +5V to source unit 102 on pin 16 of cable 106 as shown. Control logic 132 is configured to operate switch 122 responsive to a DDC/CI command received by logic 130 over cable 106 from source unit 102. Video source 112 is configured to transmit video signals to video consumer 128 in a conventional manner over cable 106.
Source unit 102 may take any of a variety of forms. For example, source unit 102 may be a personal computer, or may be a media box in an entertainment system. Display device 104 may also take a variety of forms. For example, display device 104 may be a computer monitor or a television-style display.
The power supplied by display device 104 to source unit 102 on pin 14 may vary depending on the requirements and capabilities of the two devices. In one embodiment, for example, display device 104 may provide up to 40V at up to 3A to accommodate a need for up to 120W. Other volt/amp configurations may also be employed.
While the invention has been described in detail with reference to preferred embodiments thereof, the described embodiments have been presented by way of example and not by way of limitation. It will be understood by those skilled in the art that various changes may be made in the form and details of the described embodiments without deviating from the spirit and scope of the invention as defined by the appended claims.
