The Old New Thing

That sounds like something that would be terribly annoying to catch out of the corner of your eye :)

I know red is being used to indiciate the door is locked, presumably as opposed to green for open... But really, everyone knows that a proper 'upgrade' would have been to a solid blue LED ;)

No, no: the next upgrade is clearly to a more robust security system entirely: red *strobe* lights, two of them on every lock for redundancy purposes.

Of course, I'm also left wondering why this upgrade was being applied to *major* campuses; do minor ones have to slum it with the legacy solid red lights?

(If you want a complex and procedure-heavy security system, read up on British Telecom's OBASS setup for access to telephone exchanges, complete with entry/exit counters, remote monitoring and all sorts of alarms, sensors, keypads and card points. With sites ranging from unmanned huts to large multi-level buildings, that must have been quite a rollout.)

1. Blue LEDs were not so common several years ago.

2. The blinking light would probably bother only people sitting directly in front of the entrance door (receptionist, mostly).

3. Presumably, the solid vs. blinking light is just a side effect of a different card reader model. The quote should be read as:

[For certain untold advantages, ] ...we will be upgrading the card readers on all of our major campuses. [In order to determine which card reader your building is using:] The old card readers show a solid red light when the door is locked, whereas the new card readers show a blinking red light.

4. On my (non-major?) campus, they also upgraded the card readers. The old ones were campus-specific - meaning that visitors from other campuses couldn't use their cards on our doors and vice-versa. After the upgrade (which included new cards as well), this was solved - a definite benefit.

Blinking red vs. steady green might be easier to differentiate for peope suffering from (some of the many variants of) color blindness.

I'm more interested in what happens when the door is open. What colour is it then?

It's for bug reports. Now when you call to report a problem you can tell them if it is and old reader or a new one.

Or maybe they want to avoid "reader is flashing, is it broken or will it EXPLODE?" calls

Actually, color of card reader lights is far from universal.  I've seen card readers that are green when locked, and red when unlocked.  Green for secure, red for insecure.

It's just like the red/green convention for stock tickers -- there's a Western standard (red is down) and an Asian standard (red is up).  Many an uninformed newspaper editor has run the wrong file photo for a story about the Nikkei or the Hang Seng.

And then there are lightswitches...

There are pushbuttons that toggle the state of the light. Since you may not be able to see the lights you are switching from the switch, they have a red and green LED on them.

Problem is, when people come in through the front door, there is only one light swich, so the hit it and the light comes on. However, the back door has light switches for the front and back, so you see one switch showing green, the other showing red. I hit the red one since the hallway down is dark, and green would indicate it is safe to continue. Except... no. The light uses green to indicate the lights are off, red to indicate they are on. Annoying since I get it consistently wrong, and the other people get their lights to flicker.

Heck, games get it right - turn the red switch green to proceed...

I would imagine that the blinking LED is a power savings. When in the standby state it is likely that the LED is the biggest power drain in the circuit so cutting its duty cycle by 90% could likely see at least 50% power reduction. Given that the "sleep" state is the most common one that power reduction is probably close to the overall power savings for the device. I am not one to buy full sail into the green movement but standby power use is crazy in some devices.

I would imagine that the blinking LED is a power savings. When in the standby state it is likely that the LED is the biggest power drain in the circuit so cutting its duty cycle by 90% could likely see at least 50% power reduction. Given that the "sleep" state is the most common one that power reduction is probably close to the overall power savings for the device. I am not one to buy full sail into the green movement but standby power use is crazy in some devices.

The upgrade was intended to reduce power consumption.

It's an homage!  http://www.catb.org/~esr/jargon/html/B/blinkenlights.html

Perhaps there were other reasons for making the change, and the blinking light tweak was just an easy way to figure out whether a particular unit was upgraded.

Solid green and red a fine as long as you can tell the two apart. What if you cannot?

Now if they can make all your doors (not just the sliding ones) do the Star Trek 'swooosh-shum' noise then you really have the perfect workplace.

I hate blinking lights!  My LED monitors make the power light blink when the monitor is powered down by the OS.  That is annoying; I want to tell the monitor to "stop that anoying blinking".

Why not replace simple LEDs with a backlit lcd? The it could display "CLOSED" or "OPENED".