The Move to Standard LCD Panels

SPWG Specification 3.0 To Reduce Power & Improve Interchangeability

by Stephen J. Bigelow

Processor, March 19, 2004 - Mobile computing platforms rely on flat-panel LCDs, but the diverse array of sizes, technologies, connection schemes, and image characteristics have limited LCD applications among manufacturers, keeping LCDs expensive and “proprietary.” LCDs are also notoriously power-hungry devices, consuming as much as 40% of a mobile system’s power budget. The SPWG (Standard Panels Working Group) has led the charge toward LCD standardization, allowing panels from various manufacturers to achieve a new level of interchangeability. This will undoubtedly lower costs and improve battery life for mobile PC users.

Driving Forces

The SPWG addresses all of the electro-mechanical aspects of flat-panel displays, says Mark Fihn, SPWG coordinator. “One of the primary goals of the SPWG specifications is to enable continuous innovation in terms of display features, including display power, resolution, brightness, viewing angle, contrast ratio, response time, weight, and other performance parameters.”

The result has been a series of specifications that have systematically helped to move the industry toward standardized flat-panel displays. “SPWG v1.0 was released in October 1999; SPWG v2.0 was released in September 2001 to broaden the scope of coverage to include higher resolutions, among other things. The SPWG v3.0, released in February 2004, further expands the scope of the SPWG standard, adding new panel sizes, resolutions, as well as defining ways to install matched inverters and for commonly measuring display performance,” says Fihn.

Inside 3.0

The SPWG v3.0 specification builds on previous versions by expanding the areas of connectivity, measurements, and power conservation. Fihn explains, “The SPWG 3.0 identifies mechanical and interface standards for four new panel sizes, with support for five additional pixel formats, with particular focus on supporting the emerging trend towards displays with wide aspect ratios.” He also highlights the importance of proper measurements, especially in a feature-conscious industry: “The SPWG 3.0 specification identifies processes by which to measure display front-of-screen, power, and cosmetic specifications, minimizing some of the specsmanship that currently goes on in the industry due to a lack of consistent display measurement parameters.”

Of course, minimizing display power demands translates to increased battery life and extended working time. “In cooperation with the Mobile PC Extended Battery Life Working Group (EBL-WG), the SPWG 3.0 specification identifies how to integrate inverters. By matching the inverter to the panel, rather than using a common inverter with different panels, display manufacturers will be able to optimize inverter efficiency, thereby reducing system level power consumption,” says Fihn.

Power management is vitally important, as is the idea of an integrated inverter. “The inverter transforms direct current from the battery to the alternating current used by the lamp that supplies light for the panel. Historically, the LCD manufacturer left the design and management of the inverter entirely up to the system manufacturer. Integrating the inverter directly into the panel module could lead to designs that are more energy efficient. Accordingly, one of the clear trends in the notebook PC display industry is to match the inverter to the display at the display module level.”

Broad Adoption

Although the SPWG hasn’t received too much attention from the popular media, the industry has certainly taken notice. “The SPWG is now composed of more than 60 companies that are specifically focused on the establishment and maintenance of standards for the notebook PC industry,” says Fihn. These include component and LCD makers, notebook PC makers, system software makers, test instrument makers, and others. A majority of panels now comply with the SPWG. “Today, about 60% of all of the LCDs used in notebook PCs are based on the SPWG specifications. It’s believed that all major notebook PC makers now commonly utilize SPWG-compliant panels,” notes Fihn.

Since discussions about the SPWG v3.0 specification started in August 2003, more than 20 new companies have started supporting the SPWG effort, but it may take a little time for the new standard to translate into actual products. Fihn says, “Display modules must first be developed to support the new standard, so it’s difficult to predict when notebook PCs will be introduced with the new panels. It should be noted, however, that one of the primary goals of the v3.0 specification is to enable interchangeability with the panels being used in existing notebook models, so we’re hopeful that SPWG-compliant panels will be broadly implemented by the end of 2004.”

The Road Ahead

The SPWG certainly intends to continue its efforts well beyond specification v3.0, and the next 12 to 24 months should see movement in panel measurements. “The display industry lacks any verification or assessment centers by which standards compliance can be measured. One of the next important steps for the SPWG will be to establish verification and assessment centers at which display performance can be commonly measured and verified,” says Fihn, also explaining that display-testing schemes must also mature. “The v3.0 specification needs further development with regard to the test instruments, calibration processes, and overall conditions related to front-of-screen performance measurements.”