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Touch Sensitive EM Doorknobs

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Doorknobs are loud. Yuck. Sometimes you need to enter a room silently.

Have you ever seen those touch-sensitive lights? They are metal and you touch them and they light up. We must make doorknobs out of this technology, with electromagnetic latches. You touch the knob, the EM latch releases, the door opens silently. You take your hand off the knob the EM latch activates and holds the door shut.

Nice and quiet.

DeathNinja, Sep 15 2003

Touch Bar release locking system http://www.patentst...04-description.html
Prior art, ca 1989. [csea, Jan 05 2008]


       I just had that very challenge!! My wife is sleeping, and I had to close the bedroom door ever so quietly…so I did it in ultra slow motion… If only I had your system [DeathNinja] +   

       Perhaps the entire door could be touch sensitive, so that it remains latched until someone gives it a push. Since you’re incorporating electromagnets, you could also build-in a door closing mechanism that works ever so silently.   

       Or.. Make the door generate power every time it is pushed (to operate the latch). It would be slam-proof. The harder it’s pushed on, the harder it pushes back.
TIB, Sep 15 2003

       Since most electromagnetic latch devices operate either full-on or full-off, and have a profoundly obvious sound when operated, what type of electromagnetic latch do you know of that will work in this application?   

       As far as I know, there are no silent electromagnetic latches as of yet. Perhaps you will need to build a microprocessor-controlled (DC or rectified AC operated) latch that will ramp the voltage up gradually from zero, in order to avoid the commonly heard click or 'thunk' (or even "buzzing", in those that operate on AC voltage) that is associated with most such devices when opening (and attenuate slowly for the re-closing of the latch)? I would suspect that the physical limits of travel in such a latch should be mechanically dampened (the most obvious choice would be hydro-mechanically) as well. Come to think of it... a simple mechanical dampening of the travel limits may well take care of the whole issue without variable voltage being involved... care to work on this and let us know?   

       By the way, if you bake a ramping voltage latch, or a mechanically dampened one, I'll expect a cut of the royalties. <G>   

       At any rate... once you have a silent actuator, this would be easily bakable. (+)
X2Entendre, Sep 15 2003

       I thought he meant: place a permanent magnet in the doorframe, and an electromagnet in the door. The EM would have to maintain constant power to hold the door ‘latched’.   

       Come to think of it, why not use the same method refrigerators do? A magnetic strip, and a rubber shock absorber. That should close fairly quietly.
TIB, Sep 15 2003

       Since these are interior doors they just need enough "grab" to hold the door shut and resist things like cats. These are not meant to prevent entry into the room. Most interior doorknobs don't have locks anyway. The only difference is that they can withstand more force without opening. I figure there would be a separate mechanical lock that you could engage if you really wanted to lock the door. The whole system would probably run off DC current. There could be a centrally-located transformer (like in the attic) that feeds all the doors through low-voltage wiring, so even if the transformer hummed a little you wouldn't hear it.
DeathNinja, Sep 15 2003

       Sliding doors just seem so much more efficient, in terms of space used compared with swinging doors, that I wonder why we don’t see them everywhere. If you have some empty wall next to a doorway, you have a perfect candidate location for a sliding door.   

       [DeathNinja]: Maybe you could make a door that works something like the one’s on Captain Kirk’s Enterprise. Push a small button next to the door (or touch plate), and it opens. This would be more complicated than a manually operated door, but the coolness factor is really up there.... but then you'd need that 'swiiiish' sound effect...
TIB, Sep 16 2003

       This would be great for making a Psycho entrance on a soaped-up spouse.
FarmerJohn, Sep 16 2003

       [DN], it's obvious that you only want us to get them so you can enter our houses stealthily and rob us blind.
jivetalkinrobot, Sep 17 2003

       Baked. Several of my company's offices buildings have these as a safety feature. The door requires one to swipe an ID card to enter a secure area, and the EM lock releases. To exit, the EM lock triggers on your skin's galvanic response when you grasp the push bar, allowing a quick exit.
bpilot, Jul 18 2004

       //Sliding doors just seem so much more efficient, in terms of space used compared with swinging doors, that I wonder why we don’t see them everywhere.// [TIB]   

       I would imagine the cost of installation of a sliding or pocket door is much higher than a swinging door.
GenYus, Jul 19 2004

       Why have external power? You should be able to use the door handle (assume a round knob) to be put into a certain mode that, when the door knob is either constantly rotated, or rotated back and forth, generates enough electricity to charge the small battery in the handle or door. The battery then runs the latch for a few days/weeks until the charge is gone. Then you can recharge at your convenience.
ooglek, Mar 15 2006

       I agree with [jivetalkinrobot]. Why would you want doors to be silent, AND be a ninja, unless you plan to rob us all? Or maybe you'll rob something big.   

       The White House has enough money to buy these doors! And if you sell them, then you can rob 'em and get twice the money! Brilliant! Maybe I'll do it!   

       Just kidding of course. I don't know 'bout this idea. This seems like an unneccessary implementation of technology in our everyday lives, and that makes me nervous of hackers and such, and that makes me say "no". [-] sorry.
TahuNuva, Jan 05 2008


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