Vladimir Zworykin:
The Iconscope and the Kinescope

Vladimir Zworykin

Vladimir Zworykin wanted to know two things when first developing the television... Would the answers change the world…??

Let's take a look…!

Question #1...

How do you efficiently convert an image into an electrical signal...?

Question #2...

How do you send that electrical signal to another location so that it can be accurately and clearly seen as an optical image on a view screen...?

And yes… The answers would change the world!!

In June 1908 one of the early pioneers of video, Alan Archibald Campbell-Swinton, published a letter in the scientific journal Nature in which he detailed how a fully electronic television system could be built by using cathode-ray tubes as both imaging and display devices.

At the time Campbell-Swinton published his letter he noted however that "no photoelectric phenomena at present known will provide what is required". Even though he didn't have the means to do it... Probably Campbell-Swinton's biggest contribution to video was that he did your eyes and publish evidence that you could convert an optical image into an electrical signal. Other scientists agreed with them and rapidly push the work forward.

Vladimir Zworykin was one of those scientists and became one of the  key figures in the history of television and video.

Who was Vladimir Zworykin?

Vladimir Zworykin was born July 29, 1888 in Murom, Russia.

A picturesque ancient town nestled on the banks of the Oka River in the Vladimir Oblast region of Russia.

Vladimir displayed an aptitude for engineering at an early age and earned a degree in electrical engineering from the St. Petersburg Institute of Technology in 1912. While at St. Petersburg... Vladimir was one of the early students of Prof. Boris Rosing, one of the very early pioneers of television, and became inspired by his professor's work.

It was then that he started his quest to build an all-electronic television system. His work was interrupted however when war came to Europe. Zworykin became an officer with the Russian Signal Corps during World War I working in the radio experiments unit.

Surviving the war he then continued his research but, in 1919, decided to immigrate to the United States during the chaos of the Russian Revolution. He'd seen enough of war and wanted to continue his research into building a workable all-electronic television system somewhere where there was peace and security.

The Quest for an All Electronic Television...

Zworykin almost immediately went to work for Westinghouse laboratories as a research engineer in 1920.

Working at Westinghouse laboratories gave Zworykin the opportunity to continue his experiments in building a television system where cathode ray tubes would serve as both transmitter and receiver.

After working for some time on his ideas Zworykin felt that he was ready to demonstrate a working system so… Sometime in late 1925 or early 1926 Zworykin was able to give a demonstration to Westinghouse management of an actual working television system.

After seeing the demonstration Westinghouse management told Zworykin to… “Devote your time to more practical endeavors”.

His television system still had a long way to go at that point...! This did not dissuade Zworykin however... he knew this could be done and he continued to perfect his system.

He was convinced that the two parts of this system the iconoscope (the camera) and the kinescope (the monitor) could someday be the primary components of a system that would allow a viewer at one location to remotely see (in real-time) what was taking place at another distant location.

The Two Parts of the Zworykin System...

The two parts of Zworykin’s system were the Iconoscope and the Kinescope.

#1. The Iconoscope was the name given to the cathode ray tube that served as the television camera tube…the heart of the television camera itself.

This was the tube that converted the optical image into electrical impulses that could then be transmitted to a receiving station and from there retransmitted over a distance to the television viewer.

#2. The Kinescope was the name given to the cathode ray tube that served as the receiver of the electrical image.

This was the tube that decoded the transmitted electrical impulses back into an optical image that could be seen by the television viewer. This is the heart of the television set… the picture tube.

How Did the Iconoscope Capture the Images?

The Iconoscope was the main component of the first video cameras...

At the heart of the iconoscope is a special photoelectric plate called a Mosaic... Why mosaic...? Because the plate is  essentially a pattern formed from small pieces of material... A mosaic  of electrically isolated photosensitive granules. So... the plate itself is coated with photosensitive material that is very sensitive to electrons hitting it.

Back in those days... It was usually a plate made of Mica (aluminum silicate) that on one side is covered with billions of tiny grains of silver that act as photoelectric cells and on the other side a coat of silver causing the plate itself to act as a capacitor (an electrical device that holds a charge and will discharge electricity). 

By use of a lens… light is directed into the cathode ray tube and is converted into an electron stream that is then swept across this mosaic plate in rows. This idea of scanning in rows was taken from the work of Philo Farnsworth. The tiny charged particles from the electron stream hit the plate which causes each tiny grain of the photoelectric material covering the plate to build up a corresponding electrical charge.

The amount of charge in each grain depends on the amount of light coming through the lens at that particular moment thus creating lighter and darker areas on the plate.

Some of the photoelectric cells receive a lot of light and some receive very little which creates these lighter and darker areas on the plate. The sum of these charges collectively forms an electrical "image" on the plate.

One full sweep equals one picture and each picture is composed of 525 scanning lines.

The plate is continually scanned by the stream of electrons with the beam skipping every other line so the picture is interlaced. Interlacing allows the eye to compensate for the change in picture and position allowing the viewer to perceive what appears to be a smooth transition from one picture to the next.

The electrically charged material on the plate will hold that charge until it is changed by another sweep of electrons during the scanning process. The beam continually returns to scan the plate creating a new  electronic picture every time. 30 pictures a second are created. Each picture, of course, is a still  picture but at 30 pictures a second the illusion of motion is created. As the scanning process across the plate occurs electrical impulses are released and are constructed into an electrical signal.

The resulting signal from the iconoscope is then amplified and transmitted to a receiving station. Once the signal has been received at the receiving station it is then re-amplified and retransmitted through the air to be picked up by receiving antennas and processed by the television set (kinescope) into images. So that's how the images were captured and transmitted…

But… How were they picked up and displayed at the other end…?

How Do You Display Images? The Kinescope...

The Kinescope is the receiving cathode ray tube. It is what we now call the picture tube in the TV set...

It is similar to the Kinescope but has a fluorescent (phosphorus) viewing screen. Electrons bombard the back  of the fluorescent face of the tube (the receiving screen) where the electrical impulses being transmitted are changed back into a spot of light and the billions of these spots of light form a picture.

The quick succession of pictures at 30 (still) pictures a second creates the apparent motion that you see. Sort of like the old animation trick of flipping rapidly through a stack of drawings but this time done electronically.

In the decades that followed the invention of the Iconoscope and Kinescope, improved camera and receiving tubes appeared but, many of them however were based on the same basic principles as the iconoscope and kinescope and featured very similar designs.

Zworykin Teams with the Godfather of Television... David Sarnoff...

After the lukewarm response by Westinghouse to the first demonstration of his television system in late 1926 or early 1927... Zworykin with the help of other engineers, kept working to further refine the all-electronic television.

In 1929 he again demonstrated an improved television system to Westinghouse, but again they were less than enthusiastic about his system. But… Zworykin's luck was about to change…  Later in 1929, Zworykin joined the Radio Corporation of America (RCA ) which was being run by the man who would later become the godfather of television, David Sarnoff.

Sarnoff saw the vast potential in the television and funded Zworykin’s further research and development of the medium. Sarnoff was determined that RCA would be the leader in this new entertainment medium and he would spare no expense to make that happen. His battles to obtain the patent rights to the inventions and technologies associated with the all-electronic television are legendary… Especially... the battles with Philo Farnsworth.

By 1935 the television system had been perfected to the point that it was used successfully at the 1936 Berlin Olympic Games. More improvements quickly followed... And the system was adopted by the BBC for experimental public broadcasting in England.

RCA introduced the television system to the US public at the 1939 World's Fair in New York City. The fair’s opening ceremonies were telecast 10 days later by the then newly formed National Broadcasting Company (NBC) headed by David Sarnoff.

World War II delayed the spread of television but... By 1950 there were over 10 million television sets in the US alone... And most of them using the same basic technology as Zworykin’s iconoscope and kinescope.

Zworykin later became a vice president and head of RCA’s electronic research laboratory... He was instrumental in producing ... among other inventions...the first electron microscopes. He held over 120 patents in his lifetime.  He retired in 1954 and held the title of honorary vice president of RCA throughout the rest of his life.

To his credit, Zworykin during his life never claimed to be the sole inventor of television and credited many engineers with helping to develop the medium.

What Was Zworykin's Opinion Television in His Later Years?


When asked his feelings about children watching television he was very famously quoted…

  • “I hate what they've done to my child… I would never let my own children watch it”

And his most favorite thing on the television set itself...

  • “The switch… the switch to turn the damn thing off”.

He died July 29, 1982 in Princeton, New Jersey.

Well… He may not have liked the modern TV programming  but he can be proud of the remarkable system that he helped create.

For better or worse…

It truly did change the world..!!

Have fun...!  Dan (Editor)

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