The ArcticLink III VX3 solution platform from QuickLogic offers smartphone and other mobile device manufactures a proven solution for extending battery life and improving display viewability in difficult viewing environments within a MIPI-DSI architecture.
The VX3 incorporates MIPI-DSI inputs and outputs, with up to four lanes in either direction and a maximum resolution supported of 1920 x 1080 at 60 frames per second (assuming a 24-bit per pixel depth). MIPI-DSI is the most popular display interface standard used in smartphones, and as such is found on the vast majority of smartphone-centric application processors/CPUs and mobile displays that are <7”.
However, even if both the display and apps processor use MIPI, that may not necessarily allow for an easy connection. Processors, which tend to be on leading-edge manufacturing nodes, generally support higher per-lane bandwidth. Most processors will support a per-lane speed of 1 Gbps. At that lane speed, 720p resolution can be supported with a MIPI 2-lane interface. Some existing mobile processors are designed to support only up to that 720p resolution, and do so only with 2 lanes. However, display driver integrated circuits (DDICs), the silicon device located on the physical display that interprets the incoming display data and renders it into a format acceptable for display panels, are generally not manufactured using the latest nodes. As older nodes do not support the higher speeds of new nodes, DDICs can often be limited in their per-lane speed. In some cases, DDICs are limited to speeds of 500 Mbps. While newer node DDICs are available, they are often prohibitively expensive for cost-conscious OEMs.
In this case, the ArcticLink III VX3 can assist in design. The VX3 device can accept the 2 lane, 1Gbps MIPI-DSI data from the apps processor and bridge it to a slower, 4 lane, 500 Mbps MIPI signal to the display. Additionally, the VX3 can be used in unique situations like MIPI-2 to MIPI-3 and MIPI-3 to MIPI-4.
|VX3B2F||MIPI-2||MIPI-4||Smartphones and Tablets needing a MIPI-2 to MIPI-4 bridge|
Displays are the largest single consumer of power in a typical smartphone designs. While there are numerous ways to reduce display power consumption (such as Content Adaptive Backlight Control [CABC] or ambient light correction), each method reduces display viewability, often resulting in a poor user experience. QuickLogic’s VEE and DPO’s approach to display enhancement and power savings is a radical advancement from these previous technologies. VEE HD+ is based on a model of human perception, which is in contrast to other methods of display enhancement which are based on legacy machine models of perception. The human perception model insures that the visual enhancement applied to the display content always results in a viewing experience that is most pleasing to the viewer, rather than alternative technologies which often sacrifice details in areas of the image to increase viewability in other areas.
VEE examines each pixel of every frame of video data, and judges how to best optimize the contrast ratio and dynamic range of that pixel through a pixel-unique tone curve. In keeping with the human perception model, VEE HD+ examines the pixel’s data versus data of neighboring pixels, a smaller area within the entire image, and then the entire image. This insures that the viewer experiences the content in a manner most typical of how the eye would expect to see it, rather than how a machine would best want to interpret the video data.
VEE insures that the display content is viewable in all lighting conditions, including sunlight. As all smartphone users know, it can be difficult or impossible to view content on your smartphone while outside during daylight. This is due to the fact that the display’s contrast ratio, natively around 1000:1, can be reduced to as low as an 20:1 effective contrast ratio due to ambient light and display brightness factors. VEE’s pixel-unique tone curve compensates for the low contrast ratio, creating an effective contrast ratio that approaches the native 1000:1 figure. This allows viewability of content and continued use of smartphones in all typical-usage lighting conditions.
With VEE (left) and without VEE (right)
All VEE HD+ processing is done on the VX3 device, with no processing requirements placed on the host system.
While VEE HD+ optimizes the viewing experience, DPO HD+ is working to best conserve power in the system, based upon an understanding of the ambient light of the viewer’s environment. VEE HD+’s ability to provide a unique tone curve for each pixel allows DPO+ to lower display brightness without negatively affecting the viewing experience. During the smartphone design process, an OEM can choose (1) a visual-first, (2) a power savings-first, or (3) best balance of power savings and visual enhancement setting and operation of VEE HD+ and DPO HD+. DPO HD+ power savings are completely independent of display content, allowing for predictable, consistent savings.
In field-proven systems (see below), VEE and DPO have been shown to extend battery life an average of 25%, with OEMs seeing as much as 41% single-charge battery life extensions.
(Actual results depend on implementation)
In addition to DPO HD+, the ArcticLink III VX3 integrates QuickLogic’s Intelligent Brightness Control (IBC) technology, which allows for even greater power savings. When display content is of lower contrast or dynamic range (such as streamed movies from YouTube), display brightness is often needlessly high. When active, IBC examines display data in an effort to further reduce display brightness without affecting the viewing experience. IBC can add up to an additional 10% in system power savings (content-dependent) on top of DPO’s already impressive savings.