Patent Application
20050083247
1. Field of the Invention
The present invention relates in general to the field of information display, and more particularly to a system and method for information handling system native and docking support of Digital Video Interface display signals.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
As the technology available for information handling system hardware and software components advances, the amount and types of information presented to users have increased in number and complexity, resulting in increased demand for high resolution displays. One difficulty with the presentation of information from an information handling system to a high resolution display is that higher resolutions tend to transfer larger quantities of display information at more rapid rates that have outgrown the capacity of the analog VGA standard. In order to meet consumer display quality demands, information handling system manufacturers have begun to implement the Digital Video Interface (DVI) standard. Typically, DVI is generated on a graphics memory controller hub (GMCH) or graphics processor unit (GPU) as a Digital Video Output (DVO) to a Transition Minimized Differential Signaling (TMDS) transmitter that outputs a serial signal for transmission to a display. TMDS signals are communicated at a relatively high speed of 1.65 GB/s, making signal integrity an important consideration in the communication of a TMDS signal from an information handling system to a display.
One difficulty that arises with implementation of DVI in portable or notebook information handling systems is whether to provide a DVI connector on the system itself or on a docking station. Typically, users of portable information handling systems interface external displays through a docking station that connects to the information handling system through a single connector. However, in some circumstances users of portable information handling systems desire a DVI connector on the information handling system itself, such as to connect with a projector during a presentation. Generally, daisy chain routing of a TMDS signal from a transmitter to a DVI connector on an information handling system and then to a docking station DVI connector results in excessive signal integrity degradation so that supporting separate DVI connectors on an information handling system and docking station tends to require separate TMDS transmitters for each DVI connector and a more complex software solution to provide the same display surface data to be displayed from a TMDS port for docked and undocked configurations. However, the use of separate transmitters is costly in the space consumed on a portable information handling system, in the expense of an additional TMDS transmitter and in the power consumed.
Therefore a need has arisen for a system and method which supports native and docking station DVI connectors with reduced expense and complexity.
In accordance with the present invention, a method and system are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for communicating display information to native and docking station connectors. Display information automatically communicates with a selected of a first or second TMDS transmitter based on the coupling or decoupling an information handling system and docking station to support a native DVI connector at the information handling system housing or a docking station DVI connector to the docking station.
More specifically, a DVI management system application specific integrated circuit has a multiplexer interfaced with a first native TMDS transmitter and a second docking TMDS transmitter. The multiplexer receives display information generated by information handling system processing components and output by a graphics component, such as a GMCH or GPU, as a DVO signal. The multiplexer provides the display information to the first native TMDS transmitter for output to a native DVI connector if the information handling system is not coupled to the docking station. The multiplexer provides the display information to the second docking TMDS transmitter for output through a docking connector to a docking station DVI connector if the information handling system is coupled to the docking station. The multiplexer automatically switches between the first and second TMDS transmitters by using the docking and undocking selector signal as the multiplexer output selector.
The present invention provides a number of important technical advantages. One example of an important technical advantage is that native and docking station DVI connectors are supported with the same DVO signal so that display software of the information handling system is unaffected for display of the same display surface information from TMDS-based ports for docked and undocked configurations. Minimal impact is made on space and power consumption, with the docking station TMDS transmitter providing display information to the docking station with good signal integrity through minimal additional pins of the docking connector that provide a channel for the display information. Automated switching between TMDS transmitters is provided with existing docking and undocking selection signals applied to the DVI management system to switch the multiplexer output.
The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element.
Native and docking DVI connector support for a portable information handling system and associated docking station is provided by automated selection of a first or second TMDS transmitter based upon whether the information handling system couples to the docking station. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.
Referring now to
Referring now to
In operation, with the dock/undock selector signal indicating no coupling of the information handling system and the docking station, the DVO signal passes through multiplexer 30 into first native TMDS transmitter 32 and out to native DVI connector 14 at the housing of the information handling system. Thus, a user may connect display devices, such as a projector or monitor, directly to the information handling system to present the display information of the DVO signal. If the information handling system is inserted into a docking station, the docking station connector sends selector signal 36 to multiplexer 30 to switch the output sent from multiplexer 30 to second docking TMDS transmitter 34 instead of to first native TMDS transmitter 32. Second docking TMDS transmitter 34 provides the display information through pins of docking connectors 22 and 24 in order to maintain signal integrity and then outputs the display information to docking station DVI connector 16, such as for use with an external display monitor interfaced with the docking station. Since the docking station selector switches multiplexer 30 between the first and second TMDS transmitters, the same DVO signal supports native and docking station DVI connectors to have minimal if any effect on operation of the information handling system or graphics component 28.
In alternative embodiments, separate TMDS outputs from DVI management system 26 to DVI connectors 14 and 16 are supported with various arrangements of TMDS transmitters and multiplexer 30. For instance, referring to
Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.
