System and method for detecting display disconnection

A video processing device comprising:

• a display interface coupleable to a display device;
• a display controller configured to transmit a video signal via an output node of the display interface, the video signal comprising an active segment comprising video information and an inactive segment comprising synchronization information, wherein the display interface is configured to provide the video signal by:
• providing a predetermined first current to the output node during transmission of both the active segment and the inactive segment, the display device being configured to latch the first current as a reference black level during the inactive segment;
• and
• providing a second current representative of the active segment to the output node during transmission of the active segment, wherein a total current provided to the output node during transmission of the active segment is equal to a sum of the first current and the second current;
• and
• a display detector configured to determine whether the display device is coupled to the display interface based on a comparison of a first voltage at the output node during transmission of the inactive segment to a reference voltage, the first voltage generated at the output node in response to the provision of the first current to the output node.

A method comprising:

• converting, at a video processing device, a series of pixel values to a corresponding output current;
• providing the output current to an output node of a display interface of the video processing device for transmission, a voltage of the output node varying with the output current;
• for each pixel value of the series of pixel values:
• comparing the pixel value with a threshold value;
• adjusting a count value in response to determining the pixel value is at least as great as the threshold value;
• and
• resetting the count value in response to determining the pixel value is less than the threshold value;
• and
• responsive to the count value reaching a predetermined settling value, determining whether a display device has been disconnected from the display interface based on a comparison of a reference voltage to the voltage at the output node.

A video processing device comprising:

• a display interface coupleable to a display device;
• a video digital-to-analog converter (DAC) to convert a series of pixel values to a corresponding output current and to provide the output current to an output node of the display interface for transmission, a voltage of the output node varying with the output current;
• a digital comparator comprising an input to receive the series of pixel values, an input to receive a threshold value, and an output, wherein the digital comparator is to, for each pixel value of the series of pixel values, provide a first value in response to determining the pixel value meets or exceeds the threshold value and provide a second value in response to determining the pixel value is less than the threshold value;
• a counter comprising an input connected to the output of the digital comparator and an output, wherein the counter is to:
• adjust a count value in response to receiving the first value at the input;
• reset the count value in response to receiving the second value at the input;
• and
• provide a compare indicator at the output in response to the count value reaching a predetermined settling value;
• a voltage comparator to compare a reference voltage to the voltage at the output node in response to the compare indicator;
• and
• a disconnect detect module to determine whether a display device has been disconnected from the display interface based on an output of the comparator in response to the compare indicator.

A tangible computer readable medium storing instructions which are operable upon by a computer system to manipulate the computer system to perform a portion of a process to fabricate a device, the device comprising:

• a display interface coupleable to a display device;
• a video digital-to-analog converter (DAC) to convert a series of pixel values to a corresponding output current and to provide the output current to an output node of the display interface for transmission, a voltage of the output node varying with the output current;
• a digital comparator comprising an input to receive the series of pixel values, an input to receive a threshold value, and an output, wherein the digital comparator is to, for each pixel value of the series of pixel values, provide a first value in response to determining the pixel value meets or exceeds the threshold value and provide a second value in response to determining the pixel value is less than the threshold value;
• a counter comprising an input connected to the output of the digital comparator and an output, wherein the counter is to:
• adjust a count value in response to receiving the first value at the input;
• reset the count value in response to receiving the second value at the input;
• and
• provide the compare indicator at the output in response to the count value reaching a predetermined settling value;
• a voltage comparator to compare a reference voltage to the voltage at the output node in response to the compare indicator;
• and
• a disconnect detect module to determine whether a display device has been disconnected from the display interface based on an output of the comparator in response to the compare indicator.