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58:'s delta arrangement. The main benefit of the in-line gun arrangement is that it simplified the convergence process, and did not become easily misaligned when moved, thus making true portability possible. There were many variations of this set produced from its introduction in 1966 until 1978, all using GE's Compactron vacuum tubes (valves).
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and sold for $ 249, which was very inexpensive for a color set at that time. Introduced in 1966, the Porta-Color was extremely successful and led to a rush by other companies to introduce similar systems. GE continued refining this system, up until 1978, which marked the end of production of vacuum tube type television receivers.
107:, which mix in the human eye to produce an apparent color. To produce the same resolution as the B&W display, a color screen must have three times the resolution. This presents a problem for conventional electron guns, which cannot be focused or positioned accurately enough to hit these much smaller individual patterns.
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conventional delta shadow mask tube. This differed sufficiently from RCA's design to allow GE to circumvent the patents. The GE 11" tube still had round mask holes and phosphor dots, not rectangular ones as in the later slot-mask tubes. The innovation here was with the in-line guns as opposed to the triad arrangement.
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The primary problem with the shadow mask system is that the vast majority of the beam energy, typically 85%, is lost 'lighting up' the mask as the beam passes over the opaque sections between the holes. This means that the beams must be greatly increased in power to produce acceptable brightness when
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at the back of the tube are arranged in a triangle. They are individually focused, with some difficulty, so that the three beams meet at a spot when they reach the shadow mask. The mask cuts off any unfocussed portions of the beams, which then continue through the holes towards the screen. Since the
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with the required power capabilities were introduced. The Porta Color II was their attempt at a solid state version, but did not see widespread sales. The basic technology, however, was copied into GE's entire lineup as product refresh cycles allowed. By the early 1970s most companies had introduced
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GE's design modified this layout by arranging the electron guns in a side-by-side line (the "in-line gun") instead of a triangle (the "delta gun"). This meant that after they passed through the mask they separated horizontally only, hitting phosphors that were also arranged side by side. Otherwise,
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This change, which allowed vastly simpler convergence measures, together with the use of GE's own
Compactron multi-function vacuum tubes led to reductions in size of the entire chassis. GE used the small size of their system as the primary selling feature. The original 28 pound set used an 11" tube
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are used to produce a scanning motion. The television signal is sent as a series of stripes, each one of which is displayed as a separate line on the display. The strength of the signal increases or decreases the current in the beam, producing bright or dark points on the display as the beam sweeps
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system. The shadow mask is a thin steel sheet with small round holes cut into it, positioned so the holes lie directly above one triplet of colored phosphor dots. Three separate electron guns are individually focussed on the mask, sweeping the screen as normal. When the beams pass over one of the
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Toshiba then countered this with their slot-mask system, which was somewhat in-between the
Trinitron and the original delta-mask systems. Sony attempted to stop Toshiba from producing their in-line gun system, citing patent violations, but Toshiba won this battle, and the Toshiba tube eventually
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Instead of arranging the guns, and phosphors, in a triangle, their system arranged them side by side. This meant that the phosphors did not have to be displaced from each other in two directions, only one, which allowed much-simplified convergence adjustments of the three beams, compared to the
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holes, they travel through it, and since the guns are separated by a small distance from each other at the back of the tube, each beam has a slight angle as it travels through the hole. The phosphor dots are arranged on the screen such that the beams hit only their correct phosphor.
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Over the years, the Porta Color has attracted interest as an old (dead) technology to be rescued. Once considered throw-away items, the Porta Color has become a collectible item, being the last all-vacuum tube color television made in the US.
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Later, Sony changed the whole game, replacing the shadow mask with an aperture grille and the phosphor dots with vertical phosphor stripes. They cleverly implemented a single electron gun with three independent cathodes, later branded
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The name has been variously written, even in GE's literature, as "Porta Color", "Porta-Color" and "Porta-color". The name may also refer to the specific television model, or less commonly, the style of television tube it used.
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General
Electric (GE) had been working on a variety of systems that would allow them to introduce color sets that did not rely on the shadow mask patents. Through the 1950s they had put considerable effort into the
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concept, but were never able to make it work as a basic color television, and started looking for alternate arrangements. GE eventually improved on the basic shadow mask system with a simple change to layout.
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beams approach the mask at an angle, they separate again on the far side of the mask. This allows the beams to address the individual phosphor spots on the back of the screen.
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In a color display the uniform coating of white phosphor is replaced by dots or lines of three colored phosphors, producing red, green or blue light (
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Paul
Pelczynski was the project leader in the conception and production of the General Electric Porta Color in 1966.
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83:, the phosphor gives off light, typically white but other colors are also used in certain circumstances. An
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GE produced the basic Porta-Color design well into the 1970s, even after most companies had moved to
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A conventional black and white television (B&W) uses a tube that is uniformly coated with a
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at the back of the tube provides a beam of high-speed electrons, and a set of
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Labelled sketch of delta gun and shadow mask in a color picture tube.
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Labelled sketch of in-line gun and slot mask in a color picture tube.
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arranged near the gun allow the beam to be moved around the display.
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The conventional solution to this problem was introduced by
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became the standard in most domestic television receivers.
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The Porta-Color set introduced a new variation of the
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Collecting
General Electric Porta Color Televisions
54:arranged in an in-line configuration, rather than
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79:on the inside face. When excited by high-speed
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367:"New TV tubes lock in better color pictures"
173:the "slot-mask" designs, including RCA.
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362:, November 1968, pp. 122–127, 256
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132:The General Electric Porta-Color
128:they do pass through the holes.
279:"General Electric Porta Color"
277:Television, Early Electronic.
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321:. Martin Kuhn. Archived from
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373:, May 1974, pp. 85–89
50:display tube. It had the
35:was the first "portable"
315:"In Living Porta Color"
283:Early Television Museum
143:Close-up of a slot mask
403:Early color television
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393:Television technology
319:In Living Porta Color
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398:Vacuum tube displays
119:in 1950, with their
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356:"Color for $ 200?"
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39:introduced in the
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371:Popular Mechanics
360:Popular Mechanics
347:"Business News",
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177:Description
170:transistors
166:solid state
121:shadow mask
111:Shadow mask
48:shadow mask
33:Porta-Color
382:Categories
329:2015-10-17
288:2015-10-17
259:References
216:Trinitron
81:electrons
43:in 1966.
241:Penetron
235:See also
150:Penetron
77:phosphor
66:History
349:Forbes
302:New TV
24:in use
264:Notes
117:RCA
56:RCA
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