Development of the Unifax II NewsPicture Receiver – a Personal Story
By David R. Spencer
New York, October 2008
As the ‘60s drew to a close, I was fortunate to be leading a group of superb R&D engineers, many from my MIT alma mater, as part of a recently formed New Venture group at Edgerton, Germeshausen & Grier – later EG&G, Inc.
New Technology
Before the advent of low-cost lasers and high-resolution inkjet printing, when conventional imaging technology was wet-process photography, part of our group was working with directelectrostatic printing for some low-resolution military programs. Wherever we wanted to print, electric charge was deposited on the surface of a dielectric-coated paper by a metal stylus; the latent image becomes visible by bringing oppositely charged toner in contact with it.
Mounting a sheet of paper on a turning lathe, we brought a stylus into contact with the paper -- instead of the normal cutting tool -- and by applying a pulse of voltage to the stylus we deposited a spot of electric charge on the paper, then hand-brushed some oppositely charged dry toner over the media.
Voila! A black spot appeared, and with the help of a heat gun (I think it was for shrink-wrapping) we permanently fixed the toned spot to the paper.
Unfortunately, the electrostatic process works far more reliably in a black-and-white mode -- not grayscale.
We Wanted to Print Photos
The printing industry has faced this problem in technologies such as offset lithography, which is how most newspapers and magazines are printed. They use halftones to simulate grayscale by printing only fractions of a picture element (a pixel). If the resolution is high enough, the human visual system cannot resolve within the pixel and instead we see the average coverage – or shades of gray. At the time, newspapers were printing images with up to 85 line-per-inch
halftones, magazines at up to 133 lines-per-inch, and UPI was transmitting photos at 160 pixels-per-inch.
I believe it was Seymour Friedel, a member of my team of innovative engineers, that suggested incorporating the then-emerging digital technology within the machine could provide us with precision and stability levels previously unavailable. Since research had shown that humans could only detect 1-2% differences in gray levels, we determined that we could support newspaper reproduction quality digitally with 64 levels of gray. Therefore, if we could divide each pixel into 64 resolvable sub-pixels, or halftone elements, we could provide more than the required quality level. Dividing the 160 pixel-per-inch images linearly into 64 subpixels meant that the Unifax II NewsPicture Receiver would have to resolve 10,240 sub-pixels per inch – each sub-pixel would have to be about one ten-thousandth of an inch (0.00010", or about 2.5 microns)!!!
Electrostatic technology was appealing because of its relative stability over temperature, humidity, and atmospheric pressure variations. However, direct-electrostatic technology had one very significant drawback: the size of the charged and subsequently toned spot could not be smaller than the size of the physical stylus tip that deposited the charge, and as the size of the stylus was made smaller it would both wear faster and more easily break.
Our breakthrough came when Al Libbey, another member of my stellar team, and I realized that the same stylus that deposited the charge (that attracted oppositely-charged toner) could deposit opposite-charges itself – which would repel the toner, leaving the white paper. And we could control the size of the charged part of the paper by how far the stylus moved before we switched from depositing charge to depositing opposite charges – the direction of the voltage depositing the charge was switched. For a constant moving stylus speed (or moving paper under the stylus) that was simply how fast we changed the stylus voltage! The tenthousandth of an inch incremental resolution was economically within our grasp.
A significant refinement came when we further realized that the shape of the spot was determined almost solely by the shape of the trailing edge of the stylus. While a round stylus created a crescent-shaped spot, flattening the trailing edge of the stylus created a more uniform rectangular spot. Further refinement (with the help of Joe Furtado, our jeweler-technician) resulted in a slanted D-shaped stylus tip – significantly larger than the spot we were printing, but with a carefully shaped straight trailing edge. Introducing a small angle and allowing overlap with the previous scanned line improved the two-dimensional performance.
Demo to the Boss
The highlight of our development was when we had to demonstrate our progress to the big boss – Kenneth Germeshausen (Germs with a hard “G”, as he was affectionately known), the middle letter of our company, EG&G. Germs was a revered founder, and he had approved our R&D effort – we were just a little anxious. To demonstrate our ability to actually print a quality photo, we attached a light source and a focused photoelectric detector to another part of the lathe. We mounted a photo of Germs on that part of the lathe – and printed a copy on the lathe as he watched!
Reducing Toner Noise
Things were very promising, but the pictures seemed somewhat noisy. On close examination, we realized that trying to achieve 2.5-micron incremental resolution with 5-10 micron dry toner particles was our problem. The solution (double entendre intended) was to use liquid toner, whose toner particles are sub-micron in size.
That required designing a plumbing system inside the machine for the isopar-based liquid toner mix. And liquid toning, which had been used in copiers by firms such as SCM and Canon, yielded notoriously low densities. Our modest page throughput allowed us to overcome this obstacle, and we could finally produce
high-quality newspictures.
Personal Competition
In business there is always competition.
While I was pursuing my Masters degree at MIT, I studied under two excellent mentors, Professor Thomas Huang and Professor William Schreiber. Bill Schreiber was somewhat of an entrepreneur, and he convinced the Associated Press that their new newspicture receiver should use an alternate new technology – dry-silver media – and he was the one to design and build it for them. So there I was, in competition with my mentor, pitching a directelectrostatic printer to UPI while my mentor pitched a dry-silver printer to AP.
Our design offered better and more stable image quality, while theirs offered machine simplicity (is my bias showing?). We both got contracts to turn our visions into practical products.
The Unifax II NewsPicture Receiver
Three novel approaches were incorporated into the final Unifax II NewsPicture Receiver design: internal analog-to-digital processing, high-resolution direct-electrostatic printing, and liquid toning. The result was a strong competitive offering that produced sharp and durable prints, and served the industry for 20 years.
New York, October 2008
As the ‘60s drew to a close, I was fortunate to be leading a group of superb R&D engineers, many from my MIT alma mater, as part of a recently formed New Venture group at Edgerton, Germeshausen & Grier – later EG&G, Inc.
New Technology
Before the advent of low-cost lasers and high-resolution inkjet printing, when conventional imaging technology was wet-process photography, part of our group was working with directelectrostatic printing for some low-resolution military programs. Wherever we wanted to print, electric charge was deposited on the surface of a dielectric-coated paper by a metal stylus; the latent image becomes visible by bringing oppositely charged toner in contact with it.
Mounting a sheet of paper on a turning lathe, we brought a stylus into contact with the paper -- instead of the normal cutting tool -- and by applying a pulse of voltage to the stylus we deposited a spot of electric charge on the paper, then hand-brushed some oppositely charged dry toner over the media.
Voila! A black spot appeared, and with the help of a heat gun (I think it was for shrink-wrapping) we permanently fixed the toned spot to the paper.
Unfortunately, the electrostatic process works far more reliably in a black-and-white mode -- not grayscale.
We Wanted to Print Photos
The printing industry has faced this problem in technologies such as offset lithography, which is how most newspapers and magazines are printed. They use halftones to simulate grayscale by printing only fractions of a picture element (a pixel). If the resolution is high enough, the human visual system cannot resolve within the pixel and instead we see the average coverage – or shades of gray. At the time, newspapers were printing images with up to 85 line-per-inch
halftones, magazines at up to 133 lines-per-inch, and UPI was transmitting photos at 160 pixels-per-inch.
I believe it was Seymour Friedel, a member of my team of innovative engineers, that suggested incorporating the then-emerging digital technology within the machine could provide us with precision and stability levels previously unavailable. Since research had shown that humans could only detect 1-2% differences in gray levels, we determined that we could support newspaper reproduction quality digitally with 64 levels of gray. Therefore, if we could divide each pixel into 64 resolvable sub-pixels, or halftone elements, we could provide more than the required quality level. Dividing the 160 pixel-per-inch images linearly into 64 subpixels meant that the Unifax II NewsPicture Receiver would have to resolve 10,240 sub-pixels per inch – each sub-pixel would have to be about one ten-thousandth of an inch (0.00010", or about 2.5 microns)!!!
Electrostatic technology was appealing because of its relative stability over temperature, humidity, and atmospheric pressure variations. However, direct-electrostatic technology had one very significant drawback: the size of the charged and subsequently toned spot could not be smaller than the size of the physical stylus tip that deposited the charge, and as the size of the stylus was made smaller it would both wear faster and more easily break.
Our breakthrough came when Al Libbey, another member of my stellar team, and I realized that the same stylus that deposited the charge (that attracted oppositely-charged toner) could deposit opposite-charges itself – which would repel the toner, leaving the white paper. And we could control the size of the charged part of the paper by how far the stylus moved before we switched from depositing charge to depositing opposite charges – the direction of the voltage depositing the charge was switched. For a constant moving stylus speed (or moving paper under the stylus) that was simply how fast we changed the stylus voltage! The tenthousandth of an inch incremental resolution was economically within our grasp.
A significant refinement came when we further realized that the shape of the spot was determined almost solely by the shape of the trailing edge of the stylus. While a round stylus created a crescent-shaped spot, flattening the trailing edge of the stylus created a more uniform rectangular spot. Further refinement (with the help of Joe Furtado, our jeweler-technician) resulted in a slanted D-shaped stylus tip – significantly larger than the spot we were printing, but with a carefully shaped straight trailing edge. Introducing a small angle and allowing overlap with the previous scanned line improved the two-dimensional performance.
Demo to the Boss
The highlight of our development was when we had to demonstrate our progress to the big boss – Kenneth Germeshausen (Germs with a hard “G”, as he was affectionately known), the middle letter of our company, EG&G. Germs was a revered founder, and he had approved our R&D effort – we were just a little anxious. To demonstrate our ability to actually print a quality photo, we attached a light source and a focused photoelectric detector to another part of the lathe. We mounted a photo of Germs on that part of the lathe – and printed a copy on the lathe as he watched!
Reducing Toner Noise
Things were very promising, but the pictures seemed somewhat noisy. On close examination, we realized that trying to achieve 2.5-micron incremental resolution with 5-10 micron dry toner particles was our problem. The solution (double entendre intended) was to use liquid toner, whose toner particles are sub-micron in size.
That required designing a plumbing system inside the machine for the isopar-based liquid toner mix. And liquid toning, which had been used in copiers by firms such as SCM and Canon, yielded notoriously low densities. Our modest page throughput allowed us to overcome this obstacle, and we could finally produce
high-quality newspictures.
Personal Competition
In business there is always competition.
While I was pursuing my Masters degree at MIT, I studied under two excellent mentors, Professor Thomas Huang and Professor William Schreiber. Bill Schreiber was somewhat of an entrepreneur, and he convinced the Associated Press that their new newspicture receiver should use an alternate new technology – dry-silver media – and he was the one to design and build it for them. So there I was, in competition with my mentor, pitching a directelectrostatic printer to UPI while my mentor pitched a dry-silver printer to AP.
Our design offered better and more stable image quality, while theirs offered machine simplicity (is my bias showing?). We both got contracts to turn our visions into practical products.
The Unifax II NewsPicture Receiver
Three novel approaches were incorporated into the final Unifax II NewsPicture Receiver design: internal analog-to-digital processing, high-resolution direct-electrostatic printing, and liquid toning. The result was a strong competitive offering that produced sharp and durable prints, and served the industry for 20 years.
