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Before flat screens as we know then today, there were squashed CRTs

 

For many years the only way to make a TV screen was to use a cathode ray tube - as invented by German physicist Ferdinand Braun in 1897 . An electron gun at one end fired on a fluorescent surface at the other. So they were straight and long.

Sony transistor portable TV  
Sony's first transistor portable TV - it used a CRT of course
 

As the cathode ray tube approached its hundredth birthday there were several attempts at modifying it. They all flopped.

Sir Clive Sinclair and Sony both tried squashing or flattening.

 In the early 1980s Sinclair announced a £5 million, four year investment programme in a pocket FM radio/television receiver to be called Microvision.  But the idea of a squashed tube was already doomed. At the Tokyo Electronics Show in 1980 Toshiba unveiled a pocket TV with a 2 inch monochrome LCD. The pictures were rotten, and smeared on motion, but it signposted the future. 

The Sinclair Microvision's 3 inch, black and white, screen was made from a flat sandwich of two glass plates. Electrons fired from a gun at one end and were bent by electrostatic plates through 90 degrees to strike a phosphor screen on the back plate. This created a TV image which was viewed through a transparent tin oxide electrode on the front plate.

To reduce power consumption the image was squeezed,  rather like a Cinemascope movie before projection through an anamorphic lens. Sinclair put a Fresnel plate over the screen to expand it. The pictures were poor.

Sinclair promised a domestic set, that worked by back projection from three tubes to give colour. But it never happened.

Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made

Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made

Sir Clive Sinclair with his pocket flat TV and - below - the factory where it was made
Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made Sir Clive Sinclair flat screen pocket TV, how it looked and where it was madef
Sir Clive Sinclair flat screen pocket TV, how it looked and where it was madeSir Clive Sinclair flat screen pocket TV, how it looked and where it was made  
   
Sir Clive Sinclair flat screen pocket TV, how it looked and where it was madeSir Clive Sinclair flat screen pocket TV, how it looked and where it was made  
Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made
Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made
How the Sinclair set worked
Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made
Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made Sir Clive Sinclair flat screen pocket TV, how it looked and where it was made

Sony competed with its own squashed tube and the Watchman black and white pocket TV. 

The pictures were better but the set was too expensive and quickly disappeared as LCDs started to roll off Japanese production lines.

Sony also made  a flat screen pocket tube TV Sony also made  a flat screen pocket tube TV
Sony also made  a flat screen pocket tube TV

Sony also made  a flat screen pocket tube TV

Sony's pocket tube TVs
Sony also made  a flat screen pocket tube TV Sony also made  a flat screen pocket tube TV

Scrapped components for the Microvision turned up a few years later in a bargain basement catalogue. The circuitry was going for 30p and the casings cost £2 pounds.

 The Watchman was recycled as a video entryphone.

The Beam Index tube was superficially similar to the squashed CRT used by  Sony and Sinclair but whereas these  screens gave only black and white pictures, the BI tube gave colour. The electron beam was turned through 90 degrees to scan an angled screen on the side of the tube.

As with a conventional colour tube, the screen was coated with red, green and blue phosphor strips. But whereas a conventional tube has three guns, with masking to direct each gun beam only onto one set of colour phosphors, the BI tube used a single gun whose single beam was continually switched in position to land on different coloured phosphors.

Beam positioning had to be very precise, so extra "index" phosphors were deposited between the colour phosphors. The extra phosphors generated light which was sensed by detectors which controlled the beam position.

 Sony sold the Indextron portable tv set in Japan. Its 4" BI tube looked very similar to an LCD screen. The tube TV was larger than an LCD set of similar screen size, but cost 30% less.The falling cost of LCDs soon undercut Beam Indexing, killing the system and writing off Sony's investment.

Panasonic lost out too, because the company had designed a 6" BI tube for mounting in the backs of airline seats. Panasonic also lost out on twenty years of research into another CRT modification, called Beam Matrix. Although the names are similar the technologies were very different.

Panasonic flat tube TV

Panasonic flat tube TV

Panasonic's early flat tubes designs

Panasonic flat tube TV

How the Panasonic tube worked

Philips flat tube TV

Philips tried flattening tubes too
NHK plasma prototype Finlux flat tube TV
NHK Labs was already making flat plasma planels in the early 1980s
Finlux promised flat screens
NHK plasma prototype 1980s NHK plasma prototype


In 1990 Cambridge researchers discovered that  poly p-phenylenevinylene plastics emit light when fed 5 volts. Cambridge Display Technology took up the idea and in 1996 struck a deal with Seiko Epson.

CDT also did a deal with Philips, and the Dutch company dropped its legal opposition to CDT's patents. In early 1998 CDT generated press interest by demonstrating a Light Emitting Polymer screen.

Seiko had used LCD production techniques and an inkjet printer to paint a fine mosiac of LEP dots on glass panels, sandwiched with a grid of fine metal eletrodes and thin film switching transistors. Instead of holding an open press conference, with crossfire Q&A, CDT staged two days of one-to-one meetings with CEO Daniel Chapchal who "thought the device was too small to be the centre of a large event".

The device indeed small; it measured 450mm diagonally and showed a Wallace and Grommit clip in monochrome black-and-green. Resolution was 236 lines, but the pictures look sharp on the tiny screen. The image was however overlain with a swirl of granular video noise and the electrode grid was clearly visible. CDT claimed to have developed red and blue LEDs, as well as greens, and CDT  promised "a full colour, 10 or 12" screen by the fourth quarter of 1998".

"We have what is necessary" the CEP said at the briefing "If I weren't confident I wouldn't set myself up to be shot down".

By Christmas there had still been no demonstration. CDT privately showed analysts a small section of colour display and Chapchal promised the overdue press demonstration "after the end of February".

March came and the company said only that "any press announcement has to be coordinated between ourselvves and our partners".

 

   
   

 

 
 

 

 



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