Sony issues Whitepaper on 4K Digital Projection

Excerpt and Highlights:

4K compared to HD:

"Just as high definition is more involving than standard definition, 4K is far more immersive than HD. 4K projection enables you to sit close to the screen and still retain the illusion of a seamless, continuous picture. As you sit closer, you become more immersed in the visual experience."

4K Projector Compatibility:

"4K content can originate from scanning 35mm or 65mm motion picture film, from computer animation and from emerging 4K digital acquisition systems. For Digital Cinema, this content is typically played from a growing selection of third-party servers that are compatible with the 4K signal."

"The Sony 4K projectors have four input card slots, which can be configured to accept analog Y/Pb/Pr, analog RGB, SD-SDI 4:2:2, HD-SDI 4:2:2, DC-SDI, dual link HD-SDI 4:4:4, dual link DC-SDI and DVI inputs. A single standard definition video, high definition video, computer RGB or 2K Digital Cinema source can be displayed across the entire screen. Or four inputs can be displayed on four quadrants of the screen simultaneously. So 4K Digital Cinema exhibition uses four 2K DC SDI connections (one each for the upper left, upper right, lower left and lower right quadrants)."

"Thanks to the four input slots, Sony's SRX-R110 and SRX-R105 can also accept four HD-SDI inputs to display four simultaneous high definition images. Each image appears complete in its own quadrant of the common screen. And each retains full 1920 x 1080 resolution. Here's a decisive advantage for Command & Control applications that depend on multiple feeds, for Museum Exhibits, Casino Sports Book and for any application that tracks more than one video feed at a time. The projectors also support side-by-side display of two HD feeds."

SONY's SRX-R110 and SRX-R105 are first DCI compliant 4K projectors:

"Sony's SRX-R110 and SRX-R105 are the world's first commercially-available projectors to match the 4096 x 2160 resolution defined in the Digital Cinema Initiatives version 1.0 recommended specification. As of February 2006, these are the world's ONLY commercially-available projectors to do so."

The development of 4K Digital Cinema is driven by the economic and technological trends in Film Production and Post:

"As digital effects became commonplace in movie production, studios found an increasing need to "scan" filmed elements into large computer systems. Scanning enables live actors and Computer Generated Imagery (CGI) to be combined in the digital domain. As digital color correction tools have improved, the process of scanning film to computer files has also become commonplace for Digital Intermediate (DI) work, even for movies that have no need for computer generate spaceships, dragons or gorillas."

"Film scanners are classified by the maximum number of horizontal pixels per scanning line. In the metric system, "K" is short for kilo, the prefix for 1000. But in the binary system of computers, "K" equals 2 to the tenth power, or 1024. 2K scanners achieve 2 x 1024 or 2048 horizontal pixels. Today's high-end productions use 4K scanning with 4096 horizontal pixels. The microdisplay panel of Sony 4K projectors reproduces this image format directly, without the need for any down conversion."

4K versus 2K Projection:

"In comparison to the 1080-line HD picture, the 2K Digital Cinema picture is only slightly bigger—with 6.7% more pixels on the horizontal dimension and the same number of vertical pixels. As 1920 x 1080 home televisions proliferate in the marketplace, the question arises as to whether 2048 x 1080 projectors can be entrusted to maintain theatrical exhibition as the pinnacle of entertainment."

"Taking the next step, 4K is a dramatic departure in image resolution, with exactly four times the pixels of 2K presentation (8.8 million pixels versus 2.2 million)."

SONY's Silicon X-tal Reflective Display versus Established Marketplace Technologies:

"In the United States, literally hundreds of fixed-pixel projector models are available from dozens of companies...But behind the apparent diversity, almost every one of these projectors depends on just three types of microdisplays. High Temperature Polysilicon Liquid Crystal Display (H-LCD) is a transmissive technology in which the light shines through the panel. Digital Light Processing™ (DLP™) panels use a reflective micro-mirror array. Liquid Crystal on Silicon (LCoS) is a category of reflective panels that includes the Direct drive Image Light Amplifier (D-ILA™) display."

"From the outset, Sony was determined to create a fundamentally better microdisplay. We set our sights on an ambitious development project, targeting the full range of projector performance:

• High Resolution. We were committed to breaking through the conventional limits of projector performance, delivering the first consumer microdisplay projectors with full 1920 x 1080 HD display, and the first professional projectors with 4096 x 2160 resolution.

• High Pixel Density. Microdisplay panel size has an impact not only on the cost of the panels themselves, but also on the cost of the associated optical engine and projection lens. For this reason, Sony sought to achieve maximum pixel count in minimum space.

• High Aperture Ratio. Aperture ratio, also known as fill factor, describes the percentage of screen area occupied by active pixels. Larger gaps between the pixels, such as those used in H-LCD panels, tend to reduce the fill factor and heighten the visibility of the individual pixels.

• Accurate Motion Rendering. Some displays can render still pictures beautifully, yet introduce unwanted blur during fast motion sequences. Slow panel switching is the culprit. Sony aimed for high switching speed.

• High Contrast Ratio. Resolution by itself does not guarantee picture quality. Resolution and contrast work hand-in-hand to create the perception of image detail.

• Low Dark Level. Some liquid-crystal designs tend to create milky blacks. Sony sought to overcome this limitation.

• Long Operating Life. Sony sought materials and operating structures that could withstand thousands of hours in the high heat of a large-venue projector without performance degradation.

• Minimum Artifacts. Some projection systems tend to introduce artifacts not present in the original picture. Sony sought to reduce artifacts.

• Practical Manufacturing Process. Despite their performance advantages, LCoS panels continue to frustrate companies that would mass produce them. As a major consumer electronics manufacturer,
Sony absolutely required a microdisplay suitable for mass production.

• Scalability. We wanted a system that could support both small, affordable panels for mass-produced consumer televisions and large panels for Large Venue and Digital Cinema projection.

Sony found the answers in an all-new approach to reflective liquid crystal technology: the SXRD panel. The acronym is short for Silicon X-tal Reflective Display, where "x-tal" is engineering shorthand for "crystal."

SXRD microdisplay basics

"All liquid crystal displays use three elements to modulate the passage of light: a pre polarizer, a rotation medium and a post polarizer. In H-LCD microdisplays, these three elements form a sandwich. At the entrance, the pre polarizer aligns the light. In the middle, the liquid crystal rotates the required parts of the light path. At the exit, the post polarizer blocks the light not required to make the picture."

"Where H-LCD panels include all three of these elements, SXRD panels include only one: the liquid crystal. Polarization is handled by external Polarized Beam Splitters (PBS's). Before light reaches the SXRD panel, it reflects off the corresponding pre-PBS. This pre-polarized light passes through the SXRD liquid crystal where it is aligned as the image requires and reflected back out. If the SXRD pixel has rotated the light, it then is not aligned with the post-PBS polarization and is allowed to pass. If the incoming light has not been rotated, then it is reflected by the post-PBS back into the source light path."

Easier to Manufacture:

"Unlike conventional LCoS panels, which are notoriously difficult to manufacture, the SXRD panel uses a production process that Sony has perfected in the company’s own, dedicated manufacturing facilities. This has enabled Sony to bring SXRD technology smoothly into production, while taking advantage of its many benefits."

High Resolution:

"The next landmarks in SXRD resolution were the world's first commercially available 4K projectors, the SRX-R110 and SRX-R105, which take advantage of a substantially larger 1.55-inch microdisplay, Sony's second-generation SXRD panel."

High Pixel Density:

"For this reason, the "pixel density" of a microdisplay is of enormous practical importance. Higher pixel density is the key to delivering high performance at reasonable prices. While it is possible to measure the density as pixels per square inch or square millimeter, the more common measure is "pixel pitch." This measures the center-to-center distance of adjacent pixels, taking into account not only the size of the pixel itself but also the gap between the pixels. Sony's 4K SXRD panel has a pixel pitch of just 8.5 micrometers. In comparison, a human hair is roughly 70 micrometers thick. It is this 8.5-micrometer pitch that enables Sony to deliver 8.8 Megapixels on a device not much bigger than a competing panel that delivers just 2.2 Megapixels."

High Aperture Ratio:

"On all fixed-pixel panels, the pixels are separated by gaps that contain no picture information. To generate the effect of a seamless, continuous picture, these gaps should be minimized. In the SXRD panel design, all the transistors are hidden in the silicon backplane behind the reflective surface. This arrangement enabled Sony to reduce inter-pixel gaps by 90%, compared to HLCD panels. In the case of the 4K panel, the distance from the center of one SXRD pixel to the center of the next is 8.5 micrometers, while the inter-pixel gap is just 0.35 micrometers! According to Sony's review of currently available technology, this is the world's smallest inter-pixel spacing."

"This tight spacing means that 92% of the 4K SXRD panel surface is devoted to live image area—with just 8% wasted on inter-pixel gaps. So the aperture ratio (fill factor) is 92%. The silicon backplane also contributes to superb uniformity and low crosstalk."

Accurate Motion Rendering:

"Liquid Crystal is viscous, with consistency more like honey than water. When the transistors command a pixel to change its state, the liquid crystal takes a few milliseconds to respond. In motion pictures, milliseconds are important. Typical 24 frames-per-second motion pictures require the projector to display a new scene every 41.7 milliseconds. Slow LCD response can blur fast motion, for example a race car zooming past a trackside camera.

Both transmissive H-LCDs and the SXRD panel use a liquid crystal layer. But while light travels through the transmissive H-LCD liquid only once, light passes through the SXRD panel liquid twice, first coming in to strike the mirrored backplane and then reflecting out toward the screen. Because the light passes through twice, the layer of liquid itself can be half as thick. Having an LC layer that's half as thick is a huge advantage because thinner layers mean fewer LC molecules to twist. And that means more power is available to twist each molecule, for faster response.

At less than 2 micrometers, the SXRD panel's liquid crystal layer is not only thinner than in a transmissive H-LCD; it's also thinner than in the typical LCoS device. As a result, the SXRD panel responds much faster than transmissive H-LCD panels. So the picture remains crisp and clear, even during
the fastest action."

High Contrast, Low Dark Level:

"Contrast, an essential requirement of any display system, is measured as the ratio between the brightest possible bright and the blackest possible black. Sony's SXRD panels achieve superb contrast ratio, thanks to three distinct innovations.

• Sony-designed Vertically Aligned Nematic (VAN) liquid crystal. Most HLCD projectors use Twisted Nematic (TN) liquid crystal, which normally displays white. Sony achieves higher contrast because the SXRD panel uses VAN liquid crystal, which normally displays black. This crystal material is proprietary to Sony SXRD devices.

• Ultra-thin LC layer, less than 2 micrometers. The contrast ratio is defined in part by the "dark level"—the blackest possible black that the panel can display. Lower dark levels are better. As with response time, the dark level falls dramatically as the LC layer thickness is reduced. For this reason, Sony's ultra-thin LC layer—less than 2 micrometers—contributes directly to a higher contrast ratio.

• Spacer-less design. Many LCD panels require spacers in the image area to maintain a uniform cell gap. Unfortunately, these spacers interrupt the regularity of the nearby liquid crystal molecules, degrading contrast. The SXRD panel incorporates a spacer/sealer around the periphery of the live display area. As a result, the image is entirely free from spacers, to maintain maximum contrast. In addition, Sony's silicon backplane planarization helps establish an ultra-flat surface. Together with Sony's spacer/sealer, this maintains cell gap uniformity to a highly precise ±3%.

The contrast ratio of Sony's 4K SXRD panel alone is better than 4000:1, when measured with a conoscope, a tool for measuring the optical properties of bifringent materials. Total contrast ratio of the SRX-R110 and SRX-R105, when viewed on a screen with unity gain is greater than 1800:1. That's far better than H-LCD and typical LCoS projection, and comparable to the best that other digital projection technologies have to offer."

Long Operating Life:

"CRTs have phosphors that are subject to burn-in when an image stays on the screen too long. Projection CRTs are particularly susceptible, because they run at higher output to achieve high brightness. Fixed-pixel projector display panels are immune to burn-in, offering far longer life. And the SXRD panel is particularly robust."

Minimum Artifacts:

"Sony's design program for SXRD projection called for the closest possible fidelity to the original picture. For this reason, SXRD projection does not resort to color wheels, optical actuators, special dithering or sub-pixel processing."

"Even the least expensive consumer SXRD projectors use three independent microdisplay panels, one each for Red, Green and Blue. In this way, SXRD projectors display all the colors, all the time. Thanks to this three-panel design, you get stable, consistent color under all viewing conditions, in addition to high optical efficiency.

In addition, the Sony SRX-R110 and SRX-R105 mount the SXRD panels into optical engines that provide almost precisely equal length for the Red, Green and Blue beams. This feature also helps provide consistent, natural color."

"Thanks in part to the pitch of the SXRD pixels, Sony projectors do not use an optical actuator. Each pixel has its own, unique space on the screen, not shared with any other pixel. And the SXRD system displays all the pixels, all the time."

"With three separate microdisplay panels and no optical actuator, Sony SXRD projectors display all the colors, on all the pixels, all the time. And with a minimum of electronic tricks, those pixels are extremely faithful to the original source. Unwanted artifacts are kept to a minimum."