Misspellings Make RealD 3D Patent Searches Vexing

Intentional or unintentional company and inventor misspellings or spelling changes could confuse and mislead unwary patent searchers trying to analyze RealD’s intellectual property protection on RDZ 3D, the full HD passive 3D TV technology that the company announced at CES jointly with Samsung.

RealD repeatedly has declined comment on its patent filings, and those of other companies, saying only it’s “confident” of its own IP position. Our search found that RealD’s core patent portfolio was acquired when it bought StereoGraphics Corp. of San Rafael, Calif., six years ago. StereoGraphics was founded in 1980 by 3D pioneer, Lenny Lipton (who also happens to have written the lyrics for the Peter, Paul & Mary hit Puff the Magic Dragon).

Our search has found that although RealD promotes itself as “RealD,” most, but not all, of the company’s patent filings spell the company name “Real D.” This small discrepancy is sufficient not to bring up most of the company’s filings in a standard online patent search. Moreover, one key patent on RealD’s ZScreen polarizer, US 4,792,850, inexplicably spells the inventor’s name as “Lenny Liptoh” and the company as SteroGraphics, which again hides the document from conventional online searches. The same puzzling misspellings perpetuate in cross references found on at least 40 U.S. patents from others in the 3D technology field, including IGT, PureDepth Ltd., 3ality Ltd., Semiconductor Energy Lab, Kodak, Honeywell and Raytheon.

The 4,792,850 patent, filed in 1987 under the Liptoh name with co-inventors Arthur Berman, Lawrence Meyer and James Fergason, was granted a year later. The patent describes a large active filter placed in front of a CRT TV screen and suggests using the filter with a projector, as later commercialized by RealD, as one option for delivering 3D. The filter is electrically switched to change the image between two circular polarization states, so viewers with passive glasses see one view with one eye and the other view with the other eye. According to the patent, the circular polarization method overcame the problems that conventional linear polarization systems had for giving off unacceptable crosstalk ghosting if viewers tipped their heads by only a few degrees. The active filter is made from a polarizer sheet, and two liquid crystal cell sheets, sandwiched together. The LCD cells are electrically driven out of phase, so when one cell is at high voltage the other is at low voltage.

Other important patents: (1) US 4,884,876 from 1988 and US 6,975,345 from 1998, filed by Lenny Lipton and StereoGraphics, update the original idea of switching the polarity of the screen for viewing with passive glasses, but are concerned mainly with practical problems with cathode ray tube displays, where the phosphors suffer from “afterglow,” causing cross talk between the left and right views; (2) Use of the active ZScreen for theater projection was developed in patents filed by Lenny Lipton and StereoGraphics in 1991 (US 5,239,372) and 1992 (US 5,481,321) and by Lenny Lipton and Real D in 2006 (US 7,670,004) and 2007 (US 7,633,666); (3) US 5,686,975, filed by Lenny Lipton and StereoGraphics in 1993, covers a passive “polarel.” That’s a polarizer that overlays a screen display and oppositely polarizes strips of the image for viewing with passive glasses. It’s generally similar to the passive 3D TVs from LG that display interlaced and oppositely polarized left and right images.

Over the last decade, Lipton and RealD have received various patents (including US 7,760,157, US 7,502,003 and US 7,477,206) on ways of improving the performance of active polarizers, such as by using thinner sandwiches with closer bonding and anti-reflection coating, and driving the polarizer with pulsed voltages. Moreover, US 7,477,206 (filed in 2006) admits problems when using the original ZScreen (US 4,792,850) for projection. It complains of poor left-right channel isolation and inadequate image clarity, caused by reduced light transmission and slow transition time. The patented improvements included changing the switching signal to a series of positive and negative pulses that step up to 20 volts, but average at zero volts over time to avoid electrochemical damage to the liquid crystal cell material.