Hardware system for genlocking
AssigneeCompaq Information Techniques Group, L.P.
InventorChristopher D. Voltz
Life of this patent
Estimating the term…
Abstract
A computer system includes a graphics controller with a first refresh rate and a first horizontal synchronization signal; a secondary source of video data having a second refresh rate and a second horizontal synchronization signal; and a genlock unit for reconciling the first refresh rate of the graphics controller with the second refresh rate of the secondary source. The genlock unit outputs a clock signal with a frequency modulated to reconcile the first refresh rate and the second refresh rate by monitoring the phase differences of the first horizontal synchronization signal and the second horizontal synchronization signal in response to a first control signal and outputs a clock signal at a frequency corresponding to a selected clock frequency in response to a second control signal.
Claims18
A system for displaying graphics data on a display device, the system comprising:
- a graphics controller for the outputting graphics data to be displayed on the display device and the graphics controller further for outputting a first synchronization signal having a first frequency, the first synchronization signal being outputted from the graphics controller to the display device;
- a secondary source of video data available to the graphics controller;
- a genlock unit for outputting a clock signal to the graphics controller and for receiving as a feedback input the first synchronization signal output by the graphics controller, the genlock unit also for receiving a second synchronization signal associated with the secondary source of video data, the second synchronization signal having a second frequency different from the first frequency;
- and
- a graphics memory connected to the graphics controller, the graphics memory responsive to the clock signal output by the genlock unit;
- wherein the genlock unit is configured to generate the clock signal at the frequency of the second frequency based on a comparison of the first synchronization signal with the second synchronization signal, wherein the clock signal frequency is generated based on the phase difference between the first synchronization signal and the second synchronization signal and wherein the graphics controller is configured to generate the first synchronization signal outputted to the display device responsive to the clock signal frequency generated by the genlock unit.
A method of generating a clock signal for a graphics controller in a computer system, the graphics controller configured to receive data from a graphics memory, the method comprising the steps of:
- determining whether the computer system is operating in a first one of two modes;
- in response to determining that the computer system is operating in a first one of two modes, generating a clock signal for the graphics controller at a frequency of a frequency associated with a refresh rate of a secondary source based on a comparison of a refresh rate of the graphics controller with the refresh rate of the secondary source, the clock signal modulated to reconcile the refresh rate of the graphics controller and the refresh rate of the secondary source;
- outputting a sync signal to a display device, the sync signal responsive to the generated clock signal;
- and
- adjusting a transfer rate of graphical data from the graphics memory to the graphics controller responsive to the generated clock signal;
- wherein the refresh rate of the secondary source is different from the refresh rate of the graphics controller, and the clock signal frequency is generated based on the phase difference between the refresh rate of the secondary source and the refresh rate of the graphics controller.
A computer system, comprising:
- a display;
- a convergence functionality module which outputs video data at a first refresh rate;
- a computer subsystem which operates in a personal computer functional mode and in a convergence functional mode, wherein the computer subsystem comprises:
- a graphics controller for generating graphics data to the display at a second refresh rate different from the first refresh rate;
- and
- a genlock unit for generating a clock signal at a frequency of a frequency associated with the first refresh rate based on a comparison of the first refresh rate with the second refresh rate, the genlock unit for reconciling the first refresh rate of said convergence functionality module and second refresh rate of said graphics controller;
- wherein the genlock unit is prevented from, reconciling said first refresh rate and said second refresh rate responsive to the computer system operating in the personal computer functional mode mode, wherein the graphics controller outputs a sync signal to the display, the sync signal responsive to the clock signal, and the clock signal frequency is generated based on the phase difference between the first and second refresh rates.
Dependencies are inferred from the claim text.