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Automatic retracting pen


I put pens in my pockets. However, sometimes I put them in without caps, or I put in retractable pens without retracting them to keep the tip inside.

The result, as all who do this know, is from time to time a pen leaks out and ruins a pair of pants, sometimes more than that. It's expensive, and hard to solve. Since the earliest days the badge of the nerd has been the shirt pocket protector, but I put them in my pants. You could try tyvek pocket liners, I suppose, but it's hard to see how to easily add them.

I wonder if we couldn't come up with designs for retractable pens where there is some timed decay to the extension of the tip, so that it automatically returns to being inside after a modest time, perhaps half an hour to an hour. It could either just return at a very slow pace with the spring pushing back against something firm enough to keep the tip in place, or something that slowly bends and releases the ratchet. The latter is better because of course the tip must be firmly held for writing, we don't want to be able to push it back in with the pressure of writing.

The time to return might well be fairly short. Today I find that I only use pens for short bursts of writing. I do all serious writing on a keyboard. I will pull a pen out to make quick notes and then I am done. While it might be annoying from time to time, I could even imagine it clicking back after just a couple of minutes. Of course many pens would not do this -- which is a problem, because one will still be regularly picking up other pens, as one often does. But you could still reduce the number of times pen accidents happen if you bought mostly pens like this for yourself.

Electronics getting as cheap as they are these days, this could also be done instead with a sensor. Clicking the pen to extend the tip stores energy in the spring and might store it elsewhere, so that after a couple of minutes it beeps if it hasn't been reset.


... in creating a pen that won't leak.

Reminds me of the joke (true story?) about the big push to develop a Zero-G pen for NASA... punchline being that the Russians had a similar product. And decided to just use pencils.


But in essence that's what retractable pens are supposed to be, if you retract them.

A pen inherently needs to feed ink out to the tip when it's applied to paper, or more strictly as it moves over paper. But it could in theory have some system so ink only feeds when the pen is moving or has pressure on it. What matters is really the cheapest way to do this.

My thought when I read this post was: why not just use a mechanical pencil? They already exist, they're cheap, and if you don't retract the tip before putting them in your pocket the damage done to your pants is minimal. If you're loose enough in your definitions, a mechanical pencil is even doing what you ask for by only "feeding ink" (rubbing off graphite) when the tip is moving over paper.

The only disadvantages I see are that you occasionally need to advance the lead (not hard to remember, since it'll stop writing) and the marks aren't permanent (which can be advantage depending on the situation).

Are no good for signing cheques at the ATM and a few other purposes, alas.

Why do you need to sign cheques at an ATM? Are these cheques you are
depositing (how quaint!) or do you need to sign it to get cash? I haven't
physically signed (pen and ink) anything relating to financial transactions
in years, except for the occasional EC- or credit-card payment where they
want a signature rather than a PIN. (Many EC-card payments are via PIN
rather than signature now, and in Scandinavia almost all credit-card payments
are by PIN as well---not just cash withdrawls.)

The Space Pen/pencil story is almost completely bogus. Both the Russians and NASA used pencils on early flights, and discovered that broken leads and shavings were hazards in a weightless environment.

Both went to (and still use) the pressurized pens made by Fisher, which were developed privately at a cost of about $1 million, then marketed in relatively small numbers to the agencies involved for $2.95 apiece in 1968 dollars,.

Lamy made a pen to accomplish this in a different way. When you extend the pen point, the clip retracts, preventing you from clipping it into your pocket with the point extended. Retract the point, the clip comes back!

I don't clip pens to my pocket. I put them in my pants pocket. If I put them in a shirt pocket, which I often don't have, this would be a good idea.

We also need pens with a built-in alarm. They need to sound off when they're about to be put into the dryer. A pen in your pocket ruins one piece of clothing. A pen in the dryer ruins many.


I can see an easy way to detect you're in the dryer -- the temperature -- though that could be too late. Is there a cheap substance that makes a loud noise if you heat it up? I could see perhaps a little capsule of some alcohol that boils at dryer temperature, bursts and then vents out a whistle hole. But it would have to be pretty loud to hear it.

Perhaps better if you can figure a way to have something in the pen that a sensor in the dryer can detect, as that sensor can be much more expensive and the thing in the pens cheap. I don't want unique serial number RFIDs in my pens, though. Though there has been talk of RFIDs in clothes that contain the information on how to wash and dry them. In that situation, the dryer tells you you've put in a delicate item and should not have the heat so high, or perhaps put it in the dryer at all. Such a system could also work on pens -- and perhaps on fragile items that should not go in dryers, like cell phones and wallets.

In the 50's the 'Automatic Pen Company' made just such a thing that required no electronics, just a pawl, Tip it down, pawl goes over the end of the refill and holds it down, tip it up, pawl releases refill drops into the barrel. Simple, elegant, cheap, no crazy assed servos / microactuators / plasma cannons.


Pilot Explorer pen. The process of opening the clipping the pen in your pocket retracts the pen. Genius design but the idiots a pilot never properly marketed it and discontinued it.

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