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Tube Train Windows That Are Displays When Underground

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[interestingly, and I’ve never noticed before, but there’s no Public:Transport category, which is the obvious place to post ideas about the tube and buses and trams and suchlike.]

Preface: I had this idea yesterday when I was out, but a not unrelated idea was affixed to the half bakery by MaxwellBuchanan in the meantime.

In doing so, I was thinking of asking the half bakery peoples in general a quick question (which it, we all agree, isn’t really designed for, but there’s a lot of things it’s not designed either). Hence, I’m going to ask my question here, as it’s not unrelated:

Half bakers — do you know of a way of having a display and a window be the same thing at different times? In other words, when the display should be displaying something, it’s the same as a conventional transmissive display. When it’s not supposed to be displaying something, it stops displaying anything but then becomes basically a window and lets you see through it unhindered and indeed, unencumbered by the means to display synthetic imagery at other times.

And now on to the main body of my idea:

When travelling on the tube, although it is called the London Underground, in actual fact, the majority of it is not actually underground, in fact. And consequently the lesser length or duration of it is underground. However, in Zone 1, most of a journey is likely to be underground. People may or may not realise that a tube train that comes into a station underground will open all doors on the platform side no matter what, whilst when the train comes into a station that is outside in the weather, the doors won’t all open for you, you can open them yourself, if the station is overground.

The idea is that the tube train’s door windows and indeed perhaps all windows are, when underground, replaced with a view of synthetic imagery — information, education, entertainment or perhaps advertising (hopefully not completely the latter). When underground, there’s actually nothing useful to see out of the windows anyway. When the tube train approaches the station, underground, people will want to see out of the windows at the station and people at the station will want to see in to see where the rare available seat might be, so the glass will be just a window again, not displaying and not impeding the vision.

When the tube train is overground, up above, then of course, people will want to see out. The displays will not have any effect as synthetic displays, but will be fully transparent as if they are glass windows. Whether this is achieved by displaying what the window position ‘sees’, or whether it is achieved by simply switching off the display ability is the question. I do not believe it is currently possible to actively display synthetic imagery on a glass substrate whilst also allowing it to be fully transparent to the point that if the display were switched off, it’s just a window.

Ian Tindale, Dec 09 2015

Colour-blindness_20glasses The not unrelated idea was affixed to the half bakery by MaxwellBuchanan in the meantime. [Ian Tindale, Dec 09 2015]

Kinegram_20signage [hippo, Dec 09 2015]

Mystery_20Train [xenzag, Dec 09 2015]

Related.... sort of Strobeverts
[Ling, Dec 09 2015]


       It could be done mechanically, by having shutters or blinds that come down bearing the displays.   

       The window could be interlaced; alternate thin strips could be transparent, and opaque. When the outside is dark, the opaque strips will be lit up as a display. When the outside is light, the opaque strips will go dark, allowing the inhabitants to view the outer vista.
pocmloc, Dec 09 2015

       Since you only need to display while underground, why not paint the walls of the tunnels with frames of video and make the window a single LCD shutter that strobes in proportion to the train's speed.   

       Yes... a Zoetrope Tube. Although this system would be a pain to update with new content, it would have a much lower initial cost. Of course your advertisements would often run backwards or at the wrong speed, but that may add to the entertainment value.   

       Having commandeered the windows for ad space, the only things that remain are the floor, and the faces of other passengers.
mitxela, Dec 09 2015

       [mitx] - see link
hippo, Dec 09 2015

       mitxela, – well actually, I was seriously considering the ceiling space inside the carriages. On some tube carriage designs, there really isn’t a lot of ceiling space, but on others, there’s a huge amount, and you wouldn’t need this ‘sometimes it goes transparent’ thing, you just put ordinary DOOH displays up there permanently.
Ian Tindale, Dec 09 2015

       A google search for "transparent display" shows some options.
tatterdemalion, Dec 09 2015

       //Since you only need to display while underground, why not paint the walls of the tunnels with frames of video and make the window a single LCD shutter that strobes in proportion to the train's speed.//   

       That bit's baked. Not the shutter, I think the frames are painted in such a way that persistence of vision covers it. Zurich airport, shuttle between the terminals is the only instance I'm aware of, but I'm sure there are others.   

       For display underground you could do it with any sort of projection system. Since the inside of the car is better lit than the tunnel, light will reflect. The real trick would be to make it reflect inward from a projector that's nearly directly above the window. I can think of several possibilities, but I'm not certain if any of them would work without distorting the window in clear mode.
MechE, Dec 09 2015

       I hate to be a damp hamster, but I am opposed to the idea that there always has to be something to look at, just as I am opposed to the idea that everything requires background music.
MaxwellBuchanan, Dec 09 2015

       See last link..... been there, done that, now all of the counting holes in my sieve collection.
xenzag, Dec 09 2015

       A completely passive approach is possible (i.e. no need for moving parts or electrical switching).   

       Cholesteric liquid crystal have the interesting property of reflecting light in a single narrow band of colour and transmitting all other light/colours. So if you print an image with liquid crystal 'ink' (using three different liquid crystal types which respectively reflect red, green, and blue) on a transparent substrate, then you get two distinct effects depending on the lighting: when viewed in normal ambient light, the image would be invisible because the transmitted light will overwhelm/swamp the reflected light. When transmitted light is removed (when viewed against a dark background) the reflected image would become apparent.   

       Applying this to the train window: the image would be invisible when light comes through the train window (i.e. when the train is above ground), but would become visible when the train went through a tunnel.
xaviergisz, Dec 09 2015

       Err in a certain country beginning with the letter J, there isn't the "let's hide the driver away behind a big metal partition" mentality. So you can see the driver and watch the track through the front window. Also, one line has lights inside the tunnel going the whole route, so you can check out the infrastructure, trains coming the other way. It makes the journey a bit more interesting and less of a just being stuck in a metal tube underground.
not_morrison_rm, Dec 10 2015

       // I am opposed to the idea that there always has to be something to look at //   

       If observation ceased, so would the Universe ... "There is no deep reality; reality is created by observation".
8th of 7, Dec 11 2015

       Suggested categorisation - Vehicle: Subway Train.
friendlyfire, Dec 12 2015

       That doesn't make sense.
Ian Tindale, Dec 12 2015

       //"There is no deep reality; reality is created by observation"//   

       Ah, I see how that misunderhension could arise. It's quite common for physicists to insist that observation is needed in order to collapse a wavefunction and force nature to congeal into something definite.   

       In fact, it's very much the other way around. Quantum-level observations are a mechanism for reality to observe physicists, thereby collapsing the physicists' wave functions. In the absence of suitable observations, physicists are nothing but smeared-out probability functions: they believe all possible things equally.
MaxwellBuchanan, Dec 12 2015

       Reality will, sooner or later, make things that observe reality.
Ian Tindale, Dec 13 2015


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