old_tv_nut nailed it in the above post:
Quote:
Originally Posted by old_tv_nut
It's just a matter of trading some brightness for better contrast. The light coming from the phosphor gets attenuated once, but light from the room gets attenuated once going in and again reflecting back out.
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Room light reflected from the CRT phosphor surface gets attenuated twice a much as light produced by the phosphor hence contrast enhancement. I suspect that there is also a trade off with tube life, as beam current might be turned up a bit to compensate for the brightness loss.
Another enhancement can be achieved by depositing an anti-reflection coating on the *front* surface of the CRT to reduce the approximately 4% reflection of room light from that surface... I don't recall seeing a consumer TV with CRT AR coating, but perhaps it was used on some high end models.
jr