On Wed, 29 Jul 2015 16:01:45 -0700, Jeff Liebermann Gave us:
Bullshit. It is less than the white brightness, but STILL plenty enough to make a "red" signal with, which would be quite visible, and STILL more visible than the old incandescent lamps were.
On Wed, 29 Jul 2015 16:34:20 -0700, John Larkin Gave us:
Yet that IS how it was done.
There are even diffused versions with polarization gratings embedded in them, which cannot even be seen except from perpendicular to only a few degrees off axis to each side.
On Wed, 29 Jul 2015 16:29:43 -0700, John Larkin Gave us:
Someone in here already mentioned someone having "Christmas lights" where the greens were dying off.
I have light bars from/for rack interior lighting that run 24/7/365 with no problem, and they will light up an entire room.
On Thu, 30 Jul 2015 00:20:46 -0400, Spehro Pefhany Gave us:
Tri color 'pixel' LED panels? Patented? Hardly. They have been around for decades. Check out any horse track with a replay panel out in the midway.
I do not doubt that certain particulars have patents, but there are more than a few companies making large form factor RGB LED color display panels and has been for a while.
Single color LED emits some material specific spectral lines.
Traffic light standard specifies some colours based on filters used for decades.
Now the question is, does these LED spectral lines fall within the specified spectral bands ?
If not, you may have to use "white" LEDs (deep blue spectral line with phosphor) and then filter out unwanted radiation from the phosphor. Of course, you could use reddish-white, yellowish-white and greenish-white phosphors to reduce losses in filters.
A bit of webbing suggests that most LED traffic lights use clear, uncolored lenses. That makes sense. Given say, a green LED, a filter would leave it the same color and just waste light
And it's safer if an "off" green light does not look green.
Two problems with older high efficiency green and blue chips:
They are incredibly sensitive to reverse voltage but they have no internal protection. After damage they may have a microscopic arc that causes flickering from shorting.
The sapphire chips are prone to come unglued. This causes open-circuit flickering.
Some green LEDs have colourless plastic. I've got a 3W one here somewhere and some smaller ones too.
The things you know, they aren't so.
Or not.
Nah, not a Jumbotron, sequential colour illumation and switching transmssive or reflective pixels on/off between colour changes like the Nipkow disk used in early colour TV and in some DLP projectors.
Collimation not polarisation.
On 1 Aug 2015 04:45:19 GMT, Jasen Betts Gave us:
The s*it you spit make you obviously full of s*it.
On 1 Aug 2015 04:54:20 GMT, Jasen Betts Gave us:
It (they) isn't (aren't) even that. It is an optical obscurance grating.
The issue was LCDs, specifically LCDs backlit by sequential RGB LEDs.
Like a Nipow disk.
Ok, got it. With LCD response times at around 2 to 5 nsec, I would think a scanning scheme should work. I'm not so sure about the alleged increase in brightness. While each individual color LED could be made brighter, the 3 or 4 colors involved are only turned on for 1/3 or 1/4 of the time, thus decreasing the brightness.
The problem that I see is that if it were built for consumer devices, it would not offer either a price or performance advantage compared to todays LCD back or edge lit displays. Unless some obscure manufacturer is trying to circumvent some patents, I don't think that a consumer scanning display can be made to pay.
My guess(tm) is that the panel industry is putting its money into OLED and micro-LED technology, which do not use any backlighting. Most manufacturers have very expensive big OLED TV and monitor displays, probably to see if there's a market:
At rational control system dissipation 20-30ns current risetime
...Jim Thompson
I didn't mean scanning. Just use a monochrome LCD, but time-sequence the RBG LED backlights. No light is lost to color filters. Every pixel works for all three colors, so resolution is 3x better
LCDs have millisecond response times, probably inherent to the chemistry. I assume that's what prevents using an unfiltered panel with RGB sequential backlighting.
I suppose the color filtered pixels are fairly dark to room lighting, too. Their reflectance must be pretty low, round-trip through a lossy bandpass filter.
On Sat, 01 Aug 2015 10:44:49 -0700, John Larkin Gave us:
It is because they are referring to the entire panel being refreshed fully, not an individual element. and the graphics drive plays in at that point too.
I suspect that high electrical refresh rates are mostly sales points, if the LC molecules are inherently slow.
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