Patent Application
20090307382
1. Field of the Invention
The present invention relates to a graphics system capable of detecting the connection of a television set, and more particularly, to a graphics system employing a ground pin of a connector for detecting the connection/disconnection of the television set.
2. Description of the Related Art
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Currently commercialized computer systems may be provided with one or more video connectors for coupling with a TV display. If the TV display is plugged into the video connector while the computer system is turned off, the computer system after being powered on will automatically detect the presence of the TV display. On the other hand, if the TV display is plugged into the video connector while the computer system is turned on, rebooting of the computer system is usually necessary to have the presence of the TV display detected, which may be cumbersome and waste time. In one approach to overcome this issue, the detection of the hot plugging of the TV display may be made through some plug-and-play firmware provided in the computer system. However, this approach requires extra software design and pre-installation.
What is needed in the art is thus a method and system that are able to instantaneously detect the hot plugging of a video connector, and address at least the problems set forth above.
The present application describes a method and systems that are able to detect a hot plugging of a video connector in a computer device by detecting a change in the electrical state of one ground pin of the video connector. Specifically, one embodiment of the present invention sets forth a computer device that comprises a video connector, a processing unit, and a hot plugging detection circuit coupled between the processing unit and a ground pin of the video connector, wherein the hot-plugging detection circuit is configured to detect a hot plugging of the video connector based on a change in voltage potential of the ground pin.
In another embodiment, a method for hot-plugging detection of a video connector provided in a computer device is disclosed. The method comprises coupling a ground pin of the video connector to a hot-plugging detection circuit, and detecting the hot plugging of the video connector based on a change in an electrical state of the ground pin.
At least one advantage of the present invention disclosed herein is the ability for the computer device to detect the hot plugging of a video connector without requiring computer rebooting or software detection or any connector modification.
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.
The present application describes a method and system that are able to instantaneously detect a hot plugging of a video connector in a computer device by detecting a change in the electrical state of one ground pin of the video connector. Features of the invention described herein may be applicable for diverse types of video connectors such as S-Video, and High Definition TV (Component) connectors. More generally, the present invention may be suitable for detecting the hot plugging of any video connectors having more than two ground pins.
As shown, the first circuit portion 202 comprises a voltage divider 212, a metal-oxide-semiconductor field effect transistor (“MOSFET”) 214, and an inverter 216. The voltage divider 212 is coupled to a supply voltage V1 and comprises resistor elements to apply a predetermined reference voltage potential to the sensing node 206. The MOSFET 214 operates as a switch coupled between a ground and the sensing node 206 to selectively provide a grounding path to the ground pin 118 when the MOSFET 214 is turned on. The inverter 216, being coupled to a second supply voltage V2, has an input coupled to the sensing node 206 and an output coupled to the response node 208. In response to a connection or disconnection of a TV set, the inverter 216 is thereby adapted to translate a voltage change at the sensing node 206 into a corresponding electric signal at the response node 208 for representing an associated hot plugging state of the video connector 104.
The second circuit portion 204 is coupled between the MOSFET 214 and the response node 208. The second circuit portion 204 comprises an oscillator 220 adapted to apply periodic reset pulses via a transistor 222 to a gate of the MOSFET 214 so as to periodically turn off the MOSFET 214. A buffer 224 is coupled between the gate of the MOSFET 214 and the response node 208 so as to isolate the response node 208 from the effects induced by the periodic reset pulses applied by the oscillator 220.
In operation, when no TV set is hot plugged in, the sensing node 206 is set to the reference voltage potential applied through the voltage divider 212. In one embodiment, the voltage potential applied to the sensing node 206 may be about 1 volt. Accordingly, through the inverter 216, the response node 208 is set to a corresponding low voltage indicating an unplugging state of the video connector 104.
When a TV set is hot plugged into the video connector 104, the MOSFET 214 turns on to ground the coupled ground pin 118, so that the voltage potential at the sensing node 206 is about 0 volt, and the response node 208 is raised to a high voltage potential. By reading the high voltage potential at the response node 208, the GPU 112 is thereby notified of a hot plugging state of the video connector 104. The GPU 112 then can operate to switch on a digital-to-analog output (not shown) to transmit video signals through the signal pins 116 of the video connector 104 to the TV set.
Owing to the capacitance between the gate and the source of the MOSFET 214, the ON state of the MOSFET 214 is maintained, even after the TV set is actually removed. To ensure that a disconnection of the TV set can be detected, the oscillator 220 is configured to periodically apply a reset pulse to the MOSFET 214 to force a turnoff of the MOSFET 214. In one embodiment, the period of the reset pulse applied by the oscillator 220 may be about 1 second. When the TV set is hot plugged in, the reset pulses applied by the oscillator 220 will result in periodic ON-OFF switching of the MOSFET 214. However, the high voltage potential at the response node 208 is not affected owing to the buffer 224. As a result, the GPU 112 can still correctly read a hot plugging state from the response node 208.
When the TV set is unplugged from the video connector 104 after being hot plugged, the first circuit portion 202 is reset to an electrical state corresponding to an unplug state of the video connector 104 due to the reset pulses applied by the second circuit portion 204. In other words, the MOSFET 214 is turned off, the sensing node 206 recovers the reference voltage potential applied by the voltage divider 212, and the response node 208 is reset to a low voltage potential. By reading the low voltage potential from the response node 208, the GPU 112 is notified of the unplugging state of the video connector 104.
In conjunction with
As shown, the first circuit portion 202 comprises a voltage divider 212, a metal-oxide-semiconductor field effect transistor (“MOSFET”) 214, and an inverter 216. The voltage divider 212 is coupled to a supply voltage V1 and comprises resistor elements to apply a predetermined reference voltage potential to the sensing node 206. The MOSFET 214 operates as a switch coupled between a ground and the sensing node 206 to selectively provide a grounding path to the ground pin 256, 266, or 276 when the MOSFET 214 is turned on. The inverter 216, being coupled to a second supply voltage V2, has an input coupled to the sensing node 206 and an output coupled to the response node 208. In response to a connection or disconnection of a TV set, the inverter 216 is thereby adapted to translate a voltage change at the sensing node 206 into a corresponding electric signal at the response node 208 for representing an associated hot plugging state of the video connector 166, 168, or 170.
The second circuit portion 204 is coupled between the MOSFET 214 and the response node 208. The second circuit portion 204 comprises an oscillator 220 adapted to apply periodic reset pulses via a transistor 222 to a gate of the MOSFET 214 so as to periodically turn off the MOSFET 214. A buffer 224 is coupled between the gate of the MOSFET 214 and the response node 208 so as to isolate the response node 208 from the effects induced by the periodic reset pulses applied by the oscillator 220.
In operation, when no TV set is hot plugged in, the sensing node 206 is set to the reference voltage potential applied through the voltage divider 212. In one embodiment, the voltage potential applied to the sensing node 206 may be about 1 volt. Accordingly, through the inverter 216, the response node 208 is set to a corresponding low voltage indicating an unplugging state of the video connector 166, 168, or 170.
When a TV set is hot plugged into the video connector 166, 168, or 170, the MOSFET 214 turns on to ground the coupled ground pin 256, 266, or 276, so that the voltage potential at the sensing node 206 is about 0 volt, and the response node 208 is raised to a high voltage potential. By reading the high voltage potential at the response node 208, the GPU 112 is thereby notified of a hot plugging state of the video connector 166, 168, or 170. The GPU 112 then can operate to switch on a digital-to-analog output (not shown) to transmit video signals through the signal pins 254, 264, and 274 of the video connector 166, 168, or 170 to the TV set.
Owing to the capacitance between the gate and the source of the MOSFET 214, the ON state of the MOSFET 214 is maintained, even after the TV set is actually removed. To ensure that a disconnection of the TV set can be detected, the oscillator 220 is configured to periodically apply a reset pulse to the MOSFET 214 to force a turnoff of the MOSFET 214. In one embodiment, the period of the reset pulse applied by the oscillator 220 may be about 1 second. When the TV set is hot plugged in, the reset pulses applied by the oscillator 220 will result in periodic ON-OFF switching of the MOSFET 214. However, the high voltage potential at the response node 208 is not affected owing to the buffer 224. As a result, the GPU 112 can still correctly read a hot plugging state from the response node 208.
When the TV set is unplugged from the video connector 166, 168, or 170 after being hot-plugged, the first circuit portion 202 is reset to an electrical state corresponding to an unplugging state of the video connector 166, 168, or 170 due to the reset pulses applied by the second circuit portion 204. In other words, the MOSFET 214 is turned off, the sensing node 206 recovers the reference voltage potential applied by the voltage divider 212, and the response node 208 is reset to a low voltage potential. By reading the low voltage potential from the response node 208, the GPU 112 is notified of the unplugging state of the video connector 166, 168, or 170.
In conjunction with
In conjunction with
By adding a simple hardware circuitry coupled to a ground pin of the video connector, a hot plugging of a TV set and unplugging of a hot plugging TV set can thus be instantaneously detected in a cost effective manner without requiring computer rebooting or complex software detection.
The above description illustrates various embodiments of the present invention along with examples of how aspects of the present invention may be implemented. The above examples, embodiments, instruction semantics, and drawings should not be deemed to be the only embodiments, and are presented to illustrate the flexibility and advantages of the present invention as defined by the following claims.
