Waching daily Dec 30 2017

In 1960, the fledgling Sony company in Japan decided to get into the television business.

Their first foray into television was a remarkable achievement in and of itself, being the first

completely transistorized television.

The TV8-301 wasn't really a commercial hit, but it was a technical feat.

And just a year later, Sony's dealers were putting pressure on them to develop a color TV

Sony was understandably reluctant as color TV sales at the time were abysmal in Japan,

but the sales department managed to exert sufficient pressure on the engineering department

to actually start work.

Sony's visit to the 1961 IEEE trade show resulted in a glimpse of the Autometric company's

Chromatron tube.

This picture tube worked in a completely different fashion than the shadow mask picture tubes

of the time.

Rather than use three electron guns and a matrix of holes to create the separation like

the standard shadow mask picture tube did, the Chromatron used a single electron gun

combined with a vertical grille of electrically charged wires at the front of the tube.

In essence, the Chromatron relied heavily on electronics to focus the electron beam

onto the correct color.

The beam was normally focused onto the vertical green phosphor stripes present at the front

of the screen.

But the deflecting wires, placed about a half inch behind the phosphors, could push the

beam to either side, and light up the adjacent phosphor stripe.

The pattern of these phosphor stripes on a Chromatron tube, sometimes called a Lawrence

tube, were arranged as RGB - BGR.

This was necessary due to the way the deflecting wires worked.

Without a charge, the beam wouldn't be a tightly focused and would light all three

phosphors together.

But by placing a charge between pairs of wires, you would get both a tighter beam and the

ability to push it left and right to control the alternate colors.

Placing a single green stripe between two reds and two blues made this easier to accomplish,

as the direction the beam was pulled would reverse as it crossed each pair of deflection

wires, as their individual voltage potential remained constant.

Using an RGB-RGB pattern would require constantly reversing the wire grid's charge, which

would be a nightmare with the electronics of the time.

Already there was a lot of added complexity, as with a single electron beam, it needed

to be precisely modulated when producing a color image to ensure it fired with the correct

intensity as it repeatedly changed what color component it was illuminating.

The huge advantage of this chromatron tube was a much brighter picture than conventional

tubes using a shadow mask.

Even though it used just one electron gun, none of the beam's energy was lost with

this system, as all of it passed through the focusing wires.

The Chromatron also benefited from minimal required convergence tweaking.

This made the Chromatron tube much easier to configure in the factory, and less likely

to experience convergence problems requiring adjustment over time.

Remember, this was only seven years after the first color television was mass produced,

so we're dealing with brand new technologies with patents and licensing to go along with them.

Sony saw both the better picture results of this tube and the possibility to skirt around

licensing costs and leapt at the chance to take over the project.

Sony bought the entire Autometric operation from Paramount Pictures, who was behind it.

But they'd soon discover that while the Chromatron tube was a fabulous device once

built, it was a veritable pain in the ass to produce.

It took until 1964 for the first Chromatron television to actually be mass produced.

And Sony sold each one at a loss.

They were put on the market for a reasonable 198,000 Yen, but cost 400,000 Yen to build.

That's obviously not sustainable, but Sony had faith that if they just stuck with it,

they could get the manufacturing costs down by perfecting the process as the production

line matured.

Well, they couldn't.

It continued to be a nightmare.

So in 1966 Masaru Ibuka, Sony's president and co-founder, led the way to find a replacement

for the Chromatron.

Part of the reason was that General Electric's Porta-Color TVs had introduced an improved

shadow mask design and new arrangement of electron guns.

These picture tubes moved the electron guns from a triangle arrangement to an in-line

arrangement, and shifted from the dot-pattern of the original CRT designs to the vertical

triad design you see here.

The result was a much brighter picture that was close to what the Chromatron was producing,

and also eliminated many of the convergence problems conventional shadow mask tubes suffered from.

So now Sony was stuck with a money-losing product that wasn't that much better than

the competition.

The engineers at Sony would alter some of the ideas from the Portacolor and merge them

with the Chromatron's design.

Susumu Yoshida asked engineer Senri Miyaoka if the three in-line electron guns could be

replaced by a single electron gun with three individual cathodes, as this could decrease

the cost of manufacturing.

Turns out, yes you could!

This initially made for focusing challenges, but they were eventually solved.

The other big development in this new tube was similar to the Chromatron's wire grille.

The Chromatron's electrically charged wires were altered into what's called an aperture

grille, which was fundamentally similar but didn't require an electrical charge.

The aperture grill was more of a single metal sheet with slits cut vertically through it,

though it is sometimes still referred to as being made of wires.

The grille separated the color components by blocking their path much like the shadow

mask, but kept the vertical phosphor orientation of the chromatron.

The aperture grill was very simple and very effective, but perhaps most importantly to

Sony's pocketbook, was unique enough for it to be patented!

This new picture tube was called the Trinitron, and it was better than what any of the competition

were producing by a wide margin.

Introduced in 1968, these televisions were more expensive than the competition, but were

universally well received.

In fact, Sony received an Emmy award in 1973 for the invention of the Trinitron.

But what made the tube so great?

Let's compare a Trinitron tube to a standard shadow mask tube.

So, when you put a Trinitron display side-by-side with a conventional shadow-mask display, the

most obvious difference is the shape.

A Trinitron tube has a distinctive appearance due to the geometry of aperture grille vs.

the shadow mask.

A shadow mask tube has a near constant curvature across the face because the angles the three

electron beams approach at to create the individual Red, Green, and Blue color components need

to be consistent across the whole face.

The center of the tube is aligned with the electron guns in the back, but the edges need

to curve outwards to keep the inside face more or less perpendicular to the source of

the beam.

A Trinitron tube, meanwhile, only curves side to side.

It doesn't curve vertically, producing a distinctive, cylindrical shape.

This is actually a requirement of the aperture grille.

The aperture grille is fundamentally simpler than the shadow mask, as it only needs to

block the electron beams in the X dimension.

Three separate beams arranged in a line can be separated with just a slit.

With the green beam in the center, it can pass straight through.

But the red and blue beams can only pass through the left, and right, respectively.

But this arrangement requires the slits in the grill to always be perpendicular with

respect to the three beams' linear arrangement, in other words the grille had to always stay

completely vertical, as any tilt to the left or right could cause cross-over and you'd

get messed up colors.

We all know from Ghostbusters that you shouldn't cross the beams!

So, Trinitron tubes were designed to only curve in the X dimension, keeping the face

of the tube perpendicular to the electron gun along its width, and the beam separation

angle constant along its height.

The other thing you'll notice when comparing a Trinitron TV to a conventional one is a

generally much brighter image.

This was the signature "big deal" of the Trinitron.

A shadow mask separates the color components through individual holes in a metal sheet.

The earliest CRTs using a shadow mask would lose upwards of 80% of the beam's energy

to the mask itself, with only a paltry percentage actually making it through to excite the phosphors

and make the screen glow.

This was improved over time through the use of the in-line guns and the triad phosphor

arrangement introduced with the Portacolor, but the beam was still blasting its way through

tiny slits.

This required very powerful electron guns, yet still resulted in a dim picture compared

to conventional black and white TVs.

The aperture grille, meanwhile, only needs to blocks the beam from left to right to separate

the color components.

Vertically there is no separation at all, and this allows much more beam energy to pass

through it and reach the phosphors.

This alone made the phosphors glow more intensely, but the tubes were further helped along by

uninterrupted phosphor stripes rather than individual groupings.

If you look closely at a Trinitron picture tube, you'll see continuous lines going

from top to bottom with no horizontal separation at all.

When operating you see the stripes broken up, but that's merely the result of the

way the image is made via scanning in horizontal lines.

As I've said now on two separate occasions, phosphor groups you see in a conventional

tube ARE NOT pixels.

This is analog video we're talking and any Trinitron display helps to show how this is

true by only containing stripes of phosphors.

Now do you understand???

Anyway, a conventional tube's phosphor groupings have black lines above and below each grouping.

These lines further reduce the image brightness because, well, they don't glow.

I mean, that's fairly obvious now isn't it?

But they also cause other problems.

Conventional color picture tubes would display false patterns, sometimes injecting color

where it shouldn't be, when displaying an image with fine patterns.

This happens when the displayed pattern is misaligned with the phosphor grid.

Because a Trinitron doesn't have a phosphor grid, is was less prone to this occurring,

so in many instances a non-trinitron display would produce a Moire pattern or false color,

and a Trinitron wouldn't.

Perhaps the only downside to the Trinitron tube is a fine stabilization wire needed to

prevent the aperture grille from vibrating.

If the tube was exposed to loud sounds, the aperture grille could vibrate and produce

wild distortions in color.

The stabilization wire would hold them together and prevent this, but the wire itself is visible.

On smaller tubes like this only one wire is present, about a third of the way up from

the bottom, while larger tubes would have a second wire the same distance from the top.

To be fair, these wires are barely visible, since they are much finer than any of the

scan lines, but they can be an annoyance when the tube is displaying uniformly bright images.

In most cases the image displayed would contain enough variation to make the line essentially invisible.

Now, the fact that this stabilization wire was necessary may explain the Chromatron's

ultimate demise.

The charged wires probably suffered from the same vibration issues, particularly since

they were so far behind the phosphors.

And they couldn't be stabilized as easily as the Trinitron's aperture grill because

a wire holding them all together would remove the required voltage differential between pairs.

I'm willing to bet that the Chromatron would have experienced continually worse problems

as larger picture tubes were manufactured, and it would have needed even more R&D to

address it.

The many advantages of the Trinitron picture tube made Sony the undisputed king of televisions

(at least from a quality standpoint) for many years, and they were able to charge a premium

for their televisions which many people were willing to fork over.

These two TVs show how successfully Sony was with the product.

These are obviously made many years apart, but the actual picture tube is virtually the

same.

It might even have the same part number.

Sony was able to keep pumping out the same picture tubes, update the cabinets that held

them and the electronics that drove them, and they'd still be better than what the

competition offered.

From 1968 until 1998, any other manufacturer who wanted Trinitron technology in their televisions

would need to license it from Sony, and Sony was plenty happy with just making the TVs

themselves and made it difficult to do so, though Apple was notably keen on using Trinitron

tubes in their early color monitors.

However, in 1998 the patent for Trinitron expired, allowing the competition to make

their own Trinitron-like picture tubes without paying royalties to Sony.

But, the name Trinitron was still a trademark of Sony's, so they had to fudge the name.

Most of these new picture tubes would have some sort of Tron in their title, like Mitsubishi's

Diamondtron.

Sony's timing was pretty good.

By the time their patent had expired, LCD and Plasma TVs were beginning to take over.

By the mid 2000's, CRT displays represented a tiny fraction of televisions sold in mainstream

markets.

But for the entire 30 years that Sony held the patent, it was virtually second to none.

Trinitron remained important for many years, and in some applications is still the preferred

display device.

I'll tell you that for watching standard definition content, nothing beats it, and

that's why this TV stays here along with my menagerie of obsolete A/V equipment.

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