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In my perception, the most common color for monochrome computer monitors is green or white/grey, though I have seen orange monitors.

Is this genuinely the case, and if so, is there a reason for it?

dwjohnston
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    This came up on electronics.stackexchange: http://electronics.stackexchange.com/questions/58469/justification-of-the-choice-of-colours-in-monochrome-displays – pjc50 Jun 02 '16 at 10:23

2 Answers2

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There were a few reasons:

  • Old monitors had very low refresh rates (driven by hardware prices), and green phosphor has the longest afterglow (remains on the screen for the longest time)
  • Green phosphor was the first available for use in monitors (and some sources also say that monitors of this type were physically lighter)
  • It was the brightest type of phosphor
  • Human eye responds to the green color the best, (it's right in the middle of the visible spectrum) (compared to red or blue)

In short, green phosphor allowed to make cheaper monitors

Orange (or Amber which is the proper name) came later under demand from businesses, it was easier on the eyes to read but required faster refresh rate and therefore was more expensive to manufacture.

As a sidenote, many (if not all) monochrome (includes black and white) monitors only use green component (displayed as shades of grey obviously) from the color spectrum when connected to a color signal source, they don't even use other color components. This is easy to observe by hooking up a b/w monitor to VGA output.

Kuba Tyszko
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    @Kuba "As a sidenote, many (if not all) black and white monitors only use green component from the color spectrum, they don't even bother mixing other colors in." Then wouldn't it appear green? To get white you have to mix in red and blue. – snips-n-snails Jun 02 '16 at 00:17
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    @traal Black and white monitor only displays black and white picture, white means green at 100% brigtness, black means green at 0% brightness.

    It obviously means huge loss of the actual color information provided by the computer, but for text/office work - no one cares.

    This is not about additive or subtractive image reproduction using RGB colors on the screen.

     – Kuba Tyszko Jun 02 '16 at 00:19
  • If you want to have a "proof" about eyes being extremely sensitive to green - modern digital cameras use a 4 color pixel block for one real pixel (as a sensor pixel can only at the moment scan one color). 2 of the 4 pixels are for green. – TomTom Jun 02 '16 at 05:43
  • I think @traal has a point about the sidenote, but what is wrong isn't your point. It's how you're expressing that point. Try saying it as: many pre-color monitors used one color to stand in for white. – candied_orange Jun 02 '16 at 07:34
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    sidenote could end they don't respond to the other color information signals – Sean Houlihane Jun 02 '16 at 07:48
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    What exactly do you mean by the bw monitor part? Clearly for the olden times where only those existed, all the signal was bw anyways. In case of TV like PAL, there was an actual monochrome signal available too. Same for most component systems. – PlasmaHH Jun 02 '16 at 10:31
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    There was no color signals! It didn't "not respond", it was no such thing. One RCA (baseband video) connector. Not multiplexed channels like a color TV, but basic like the b&w TV. – JDługosz Jun 02 '16 at 13:03
  • Just how could you hook a VGA output to a vintage monitor? You would have to choose one of the component signals to mate to it. – JDługosz Jun 02 '16 at 13:22
  • I think he's referring to "mono-VGA" monitors, which was a common thing for a while for business use for cost reasons. They use just the signal from the green pin (along with both syncs and ground); the red and blue pins are left unconnected in the cable. – mnem Jun 02 '16 at 20:17
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    @mnem: Long before VGA, it was common to have RGB monitors connect using three cables, with sync signals being present on the green output. The signal on the green output could be viewed on a monochrome CRT. When feeding composite video from a computer to a monochrome display, colored areas would appear with a stationary checkerboard, flickering checkerboard, crawling checkerboard, or stripe pattern. Perfectly-to-spec broadcast video would have a crawling checkerboard; video from a VCR would typically show a randomly-moving herringbone. – supercat Jun 03 '16 at 15:06
  • @supercat I am aware that prior to the VGA standard there were other common mono RGB schemes as well. Its probably why they use the green signal on mono-VGA even though it has separate sync signals, simple inertia from previous sync-on-green standards. But when Kuba originally mentioned "hooking up a b/w monitor to VGA output" I'm pretty sure he was referring to "mono-VGA" specifically. – mnem Jun 03 '16 at 19:36
  • It was always a good day in school when I could get assigned to an Apple //e with an amber monitor instead of a green one. – Kyralessa Oct 22 '17 at 18:03
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Green was certainly the most common phosphor for a long time, the amber and grey monochrome monitors started to appear in the 1980s, I think.

There are two factors that I think contribute to the choice of colour. One is the stability of the particular phosphor in operation, the other is the related issue of manufacturing quality and absence of contamination, as well as other technical caracteristics of the tubes which maybe offset the cost of the phosphor component.

Sean Houlihane
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    The existance of color tv sets show that different phosphors existed much earlier. But would you really want to use red or blue for a monochrome screen? – JDługosz Jun 02 '16 at 13:05
  • @JDługosz Blue would be terrible, since the human eye is not very sensitive to blue. But red doesn't sound so different from orange, and orange was fine. – David Richerby Jun 03 '16 at 09:31
  • Lots of scopes use blue, and modern LCD monochrome test equipment displays have a blue backlight. Practicality trumps user experience for early tech. – Sean Houlihane Jun 03 '16 at 09:57
  • Amber monitors are more yellowish than "orange". The ev screens are indeed hard on the eyes and was one reason they were not popular. – JDługosz Jun 04 '16 at 02:39