I knew that the ultimate package would be one that would not involve any cables or wires, or a big controller the size of a hi-fi amplifier. But how to fit everything into a pair of eyewear?? There were some big stumbling blocks. We couldn’t get a high enough dynamic range out of a single cell all by itself. If we had to stack two of these shutters together, as we did in our headband visor, we would be using more power and have more weight. Not good for wireless battery powered eyewear.
There were other problems, for example: The literature recommended driving pi-cells with a 1 or 2 KHz carrier. The cells are driven with an overall square wave, and this 1 or 2 KHz carrier was applied to keep the cells from plating. With the carrier the ITO material would not migrate; the ions would not plate, or destroy the effectiveness of the cell. I figured that if we used a driver scheme with a low DC offset we could drop the carrier, and we did the experiments and proved that it worked. The parts shuttered and they did not plate. This allowed us to use 1/100th or 1/200th of the power to drive these pi-cells, and that meant we could have a battery-powered product. We eventually used nickel-sized batteries that are readily available at drugstores. Gave up on rechargeable which I thought was a dumb idea if we could make the product operate for a few hundred hours.
One remaining problem was the low dynamic range. A single pi-cell had a dynamic range of something like 15:1 — far too low for stereoscopic imaging, because the unwanted image will leak into the wanted image and the user will see what looks like a double exposure. It’s also called ghosting or leakage. How to cure it? For a couple of years I fooled around in the laboratory in the still watches of the night, obsessed with solving this problem. I knew there was little I could do inside the cell. We were just too small a customer to get the liquid crystal factories to make changes. Also, I didn’t know what those changes might be. By adding a retarder of the right value and at the right axis orientation between the cell and of the polarizers I became one of the first people to use optical compensation to improve the performance of liquid crystal parts. This allowed us to leap from a 15:1 dynamic range to one of more than 800:1. That’s a stupendous improvement. I am pleased to say that I amazed my genius mentor Jim Fergason who hadn’t realized I had it in me.
What was happening was that the pi-cell produced elliptically polarized light when the light from the first linear polarizer passed through it, and was incompletely analyzed by the second linear polarizer. By adding a quarter-wave retarder between the cell and one of the linear polarizers, whose axis was at the proper orientation, the elliptically polarized light was analyzed and this vastly improve the dynamic range. I was helped in these efforts by Art Berman, who sourced the parts from the various factories we used, and also by Bruce Dorworth, my lab assistant.
Once we had an electronics package together, a way to drive the cells and an IR link, we then employed a good mechanical design team, IDE of Scotts Valley, to come up with an eyewear appearance and mechanical design. We needed enough room for circuitry and batteries. We came up with what I called the “batwings,” a wide temple piece that is now characteristic of shuttering eyewear designs. In fact, the shuttering eyewear designs today are somewhat slimmed down versions of CrystalEyes. The first CrystalEyes had no folding temples as was the case for later versions. The temples when unfolded actuated a switch to turn the eyewear on. Marv Ackerman designed the infrared link using a pulse width modulation scheme to designate the left from the right fields and to make sure that the shutters were in phase. His company built the CrystalEyes eyewear for the first few years.
The marketing of CrystalEyes was an example of the sale of vaporware. We presold the concept by allowing Silicon Graphics to believe that they invented it. Our Vice-President of Marketing Jim Lipsett, was a super-intelligent and competent guy. (Jim also succumbed to cancer. I sometimes wonder what would have been the fate of StereoGraphics if both of these super-competent people, Lhary Meyer and Jim Lipsett, had lived.)
18 months prior to our efforts at SGI, in1987, we had come up with the ZScreen product, an onscreen polarization modulator for CRT monitors. It’s another story for another time but we sold hundreds of these to Evans & Sutherland, who at that time was big in computer graphics. In fact, they were the kings of computer graphics especially for molecular modeling, which you can think of as CAD for atoms. E&S segued from a workstation that was based on vector graphics (wireframes) to a raster graphics engine, and they knew that their customers in molecular modeling needed to see stereoscopically. With the ZScreen in place and passive eyewear, you could do just that. They made their graphics engine run at a high field rate, they got their supplier (Ikegami) to produce high-field-rate monitors, and they were off and running.
We beat out Tektronix’s who was also deep into the deal with E&S. Tech had their version of the modulator that used horizontal segments following the prescription of an inventor names Byatt. Too much to go into here but suffice it to say that E&S hated the lines that showed up between the segments. Despite the fact that we had nothing at the start of our conversations with them they stuck with us, more of Lipsett’s persuasive powers.
I remember that at this time of transition from vector to raster graphics two concomitant changes were on the minds of computer mavens. One was that computer graphics were going to look like the news on TV instead of wireframes. The marketing people immediately began to call this new style of image 3D, of all things. Prior to that time 3D was reserved in the public’s mind and in general usage for stereoscopic images.
The other interesting aspect of this change was the transition to color. I am not making this up but there were learned people in the field who decried the need for color. “Who needs it?” they said. “It’s good for TV but so what?” It was because people were enjoying color TV that it was impossible to ignore color for computer graphics, just as it is impossible to ignore 3D for home TV when people can see it at the movies.
Enter Jim Clark. Jim Clark is the computer scientist and entrepreneur who was one of the founders of Silicon Graphics. He has a meeting with Jim Lipsett, and amazingly suggested to him that there was, as far as he was concerned, a better way to do 3D for computer graphics than the ZScreen. He had a great idea! shuttering eyewear with an IR link. He thought it would be less expensive and a neater package. We had been working on it for years before the two Jims spoke. I was primed by my Jim before my meeting with the Silicon Graphics Jim to say “Brilliant Jim! I’ll get on it right away.” We had just about finished the CrystalEyes design work and had a proof-of-concept running. Six months later at SIGGRAPH we showed the first CrystalEyes.
If Jim Clark had thought about it at all he would have realized that it was impossible to have put anything like CrystalEyes together in six months. We got them just in time for SIGGRAPH. I was in my hotel room at the convention assembling them with a little jeweler’s screwdriver, slaving away putting them together. We got enough of them to work and got orders for hundreds and hundreds of them from Silicon Graphics. They wanted them in their color with their brand, and we were happy to comply. In no time at all SGI ate E&S’s lunch with their computer and molecular modeling applications.
We sold over a hundred thousand CEs to people in fields like molecular modeling, aerial mapping, oil and gas exploration, and CAD over a period of something less than 20 years. I believe millions of shuttering eyewear are now going to be sold for 3D TVs. A great deal of effort has gone into making high-field-rate displays in order to provide sharper images of objects inmotion. So much time and effort to make LCDs look like CRTs. That high-field rate technology can be applied to stereoscopic field-sequential television using shuttering eyewear. It means that the customer can buy after-market shuttering eyewear, which in turn means that the cost of the set can stay low but the stereo function can be enabled by purchasing the eyewear.
I’m happy to be around to see all of this come to pass. Shuttering eyewear is a good solution for stereoscopic television – providing that people will put up with wearing eyewear at home – because it will become a commodity product, and the end-user at home will be able to buy these eyewear at a low price. And they will get smaller and lighter and eventually be all but indistinguishable from polarizing eyewear.