Patent Application
20230245629
The present invention relates in general to the field of portable information handling systems, and more particularly to an information handling system dual pivot hinge signal path.
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.
Information handling systems process information with processing components that execute instructions to generate visual images for presentation at a display. The processor provides visual information to a graphics processing unit (GPU) that further processes the information to generate pixel values that define presentation of a visual image at display pixels. For example, the GPU communicates pixel values to a display timing controller that in turn scans the pixel values to an array of pixels of a display panel. For instance, a liquid crystal display (LCD) panel includes an array of liquid crystal pixels having liquid crystal materials that filter color of a backlight based upon an electrical field applied to the liquid crystal material. As another example, organic light emitting diode (OLED) material generates different colors by applying the pixel values to apply current to the OLED material, resulting in illumination. A display also typically includes a scalar that performs a variety of single instruction operations on the pixel values to efficiently process the pixel values. For instance, a scalar is generally available to adjust a display resolution when the pixel values provided to the display do not match the resolution of the display pixel array.
Displays often have a variety of refresh rates at which the pixel data is applied to the pixels so that visual images appear to the human eye to have natural motion. High end displays that support gaming applications often have very rapid refresh rates to help present visual images with as little distortion or ghosting as possible. Some GPUs include an ability to command a display to vary refresh, known as a variable refresh rate (VRR). For instance, AMD's Freesync and Nvidia's Gsync mechanisms provide a dynamic refresh rate that changes the display refresh rate in response to rendering frame rate changes in gaming video content. Synchronizing changes in refresh rate with changes in rendering framerate prevents image tearing and stuttering. The display refresh rate is synchronized to the frame rate of rendering images by adjusting a vertical blanking period when the refresh rate change is applied.
In the case of LCD display panels that are “hold” type of display devices, the LCD panel holds the refreshed image during the vertical blanking associated with variable refresh rate changes until the next fresh or next frame. The longer the vertical blanking period, the more time generally needed for the LCD display panel to hold the charges at the pixels. This makes the LCD display panel more vulnerable to luminance change and can result in an end user experiencing a perception of luminance change as a flicker under certain conditions. Other types of displays, such as OLED displays, and applications other than gaming applications, may experience a similar flicker effect. The flicker effect can detract from an end user viewing experience at a display.
Therefore, a need has arisen for a system and method which support uniform luminance at a display during variable refresh rate operations.
In accordance with the present invention, a system and method are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for presenting visual images at a display having variable refresh rate operations. Plural gamma lookup tables stored at a display scalar are selected to gamma adjust display pixel values based upon a refresh rate selected for the display. For example, a separate SRAM stores each separate gamma lookup table to support single instruction gamma adjustment of rendered visual information and the gamma adjusted visual information is selected for presentation at the display from the gamma lookup table associated with the selected refresh rate.
More specifically, an information handling system processes information with processing components disposed in a housing, such as a processor that executes instructions of an operating system and a gaming application to generate visual information in cooperation with a random access memory that stores the instructions and information. The visual information is communicated to a display, such as in pixel values provided from a graphics processor unit, along with a command to change the refresh rate of the display, such as to adapt to the framerate of a gaming application that generates the visual information. A scalar of the display receives rendered visual images from the graphics processing unit and commands to change the refresh rate of the display. The rendered visual image is applied against each of plural gamma lookup tables to generate plural inputs of a gamma adjusted rendered visual image to a multiplexor. The refresh rate is applied as a selector input to the multiplexor to select the gamma adjusted rendered visual image associated with the refresh rate selected to present the visual images.
The present invention provides a number of important technical advantages. One example of an important technical advantage is that a display presents visual images provided from an information at a variable refresh rate while maintaining a uniform luminance. The uniform luminance is supported by changing the gamma lookup table used to perform gamma correction as the refresh rate changes. The uniform luminance reduces any flicker effect that an end user might experience when a variable refresh rate is applied. The change of the gamma lookup table is applied during vertical blanking of the display between refresh rate commands to minimize viewing disruption and performed in real time with selection of several available gamma adjusted values made at a multiplexor.
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.
An information handling system graphics processing unit commands variable refresh rates at a display having a scalar that applies a selected of plural gamma lookup tables to rendered images based upon the refresh rate. 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.
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Display 26 presents visual images with pixels 30 of a display panel 28, with each pixel presenting a color as defined by the pixel values communicated from GPU 22. In the example embodiment, display 26 is a liquid crystal display (LCD) having liquid crystal pixels illuminated by a backlight. In alternative embodiments, alternative types of displays may be used, such as organic light emitting diode (OLED) displays having OLED pixels. A display system interface board 32 of display 26 accepts the pixel values from display cable 24 with a timing controller 34 supported by a scalar 36 and memory buffer 38, and scans the pixel values to pixels 30 at a refresh rate or frequency that is high enough so that the human eye cannot detect discreet changes in color and instead see the image as a whole as a video. For example, timing controller 34 follows a predefined scan pattern to read pixel values from memory buffer 38 and write the pixel values to pixels 30. Scalar 36 provides adjustments to the pixel values so that the GPU generated data accurately depicts the visual image intended by the application given the specific capabilities of display 26. For instance, in various example embodiments, scalar 36 performs resolution correction to adjust pixel values provided from GPU 22 to the resolution of the array of pixels 30 used in display panel 28. In the present example embodiment, scalar 36 performs gamma correction of the pixel values so that the visual image presented at display panel 28 has the luminance and depth intended by the application that defined the visual information.
Scalar 36 helps to prevent undesired flicker in visual images presented at display panel 28 related to changes in luminance of the visual image as variable refresh rate commands 42 are applied to change the refresh rate of pixels 30. For example, if gamma correction applied by scalar 36 is from a single gamma lookup table 40, then each refresh rate will have a slightly different luminance response for the same pixel values, resulting in a flicker of luminance change each time the refresh rate is changed. To help prevent and/or limit variable refresh rate flicker, scalar 36 includes plural gamma lookup tables 40 with each gamma lookup table associated with one or more refresh rates. As a variable refresh rate command 42 is communicated from GPU 22, scalar 36 selects a gamma lookup table 40 associated with the refresh rate and applies the gamma values of the selected gamma lookup table to gamma correct the pixel values and thereby provide a more uniform display luminance through variable refresh rate command applications. In the example embodiment, display system interface board 32 includes timing controller 34 and scalar 40, however, in alternative embodiments alternative arrangements of hardware components may be used, such as mounting timing controller 34 with display panel 28. Further, in various embodiments other processing elements may be used to perform the described functions and the display may be integrated in a portable information handling system and/or a peripheral display device.
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At step 48, when a determination is made that a variable refresh rate command has changed the display refresh rate, the process continues to step 54 to change the gamma lookup table used by the scalar for applying gamma correction to generated gamma corrected pixel values for use by the display panel pixels. At step 54 a gamma lookup table is selected for the refresh rate that is commanded for the display. In various embodiments, a gamma lookup table is stored in the scalar for each available display refresh rate. Alternatively, one gamma lookup table might support multiple display refresh rates, such as a range of display rates. At step 56, the gamma correction of the selected gamma lookup table is applied by the scalar to correct the pixel values. At step 58 the visual image is presented at the display with gamma correction applied for the refresh rate in use at the display. The process returns to step 44 to continue presenting visual images with the gamma correction for the selected refresh rate until a refresh rate change command is detected at step 48. By changing the gamma lookup table at each change in refresh rate, a more uniform luminance is provided over time.
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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.
