Keyless entry with fire escape function

Some people (myself included) find it easier to remember a combination than to always remember to grab their house key upon leaving. Realizing you left your key at home doesn't make it reappear in your hand, but a combination you use every day should become second nature.

An automatic door opener is a real help to handicapped people, but is generally not considered much more than a cool factor for most other people. However, having an electric lock and door opener that are interfaced with a fire alarm may save your pet's lives, and will "highlight" the escape route even for people while venting smoke from the area at the same time.

If the alarm was accidental or something trivial, having the door open itself has the added benefit of venting the smoke so that the alarm will stop on it's own once the source of the smoke is taken care of.

When you're out of the house, you probably want your pet to be inside so that they don't run off and get themselves into danger, or just plain run away. But if, heaven forbid, there was a fire in your house, your pet would have no way to escape.

A keyless entry lock on a residence really shouldn't have a code on both sides unless it's specifically needed for whatever reason (if there's glass near the door there should be an alarm instead of a double sided lock) but if it is indeed set up this way, a fire alarm interface is even more important, because it could now save people's lives as well as pets. But how does it work?

Basically, you've got a keypad on the door, which is set up with a door open button. If you just want to unlock the door, you enter your code. When the lock is unlocked, the door can be opened either manually, or by pressing the door open button. The door will then slowly swing open, and either remain open for a predetermined delay, or stay open until the button is pressed again. On the inside, there should be a box toggle switch that allows you to set the lock to either remain unlocked, or lock automatically upon closing the door. There should be a button labeled "lock/unlock" and another one that says "open/close".

This system should omit features like "audit trail" and 100's of user code capacity, because most homeowners don't need features like that and removing them should lower the cost without reducing the reliability of the system. It should have, say, 4 user codes that can be added and removed at any time, either by entering an existing code or by pressing buttons on the inside of the door while it's open, then programming via the keypad.

Extra functions such as time/date for automatic removal of a temporary code, more memory capacity and audit trail can be selected at purchase time at an additional cost. Also, if you're worried about a glass pane in or near the door, or if you have young children who are difficult to keep from running outside unsupervised, you could even have a second keypad on the inside, if you feel you really need it. With the fire alarm auto-open and the fail-safe lock, it wouldn't be as much of a danger as a double sided lock normally would be. Maybe a fire alarm switch that is wired to cut power to the lock when pulled could be provided as well.

The control circuits should be inside a box which is near the door, which of course is baked in a number of systems. This one system should control both the door opener and the locking mechanism. This way, the keypad would not require weird tools to open, without compromising security. The keypad is nothing more than just that- a keypad, with lights to give feedback to the user. It can be replaced separately from the control box should it stop working for whatever reason.

The lock itself should be "fail-safe"- that is, it locks when power is applied, and unlocks when power is lost. This could be either a magnetic lock, an electric strike or a solenoid-operated deadbolt which can be either surface mounted or installed into the door. Basically anything that prevents the door from opening when it has power, but allows it to open without power, can be hooked up. For security a UPS should be present with enough capacity to keep the system functional for, say, 12 hours. But a would-be burglar wouldn't even know if the lock was fail secure, or fail safe, nor would they know how long the batteries would last before it came unlocked. If a burglar knows little about any given lock, mechanical or electrical, the likelihood of them being able to defeat it is very low unless they resort to using a hammer, and ax or a saw. Hopefully someone would hear them trying to break in if they resorted to such extreme measures

For interface with a fire alarm, there are 2 options. The door can be fitted with a microphone that listens for the sound of an existing, stand alone battery fire alarm (which is "learned" upon setup by setting off the alarm while the door is in learn mode) or if the home already has a central fire/burglar alarm system, or one will be installed along with the door, it can be hooked up to the relay output of the fire alarm.

When the door gets an alarm signal, it will unlock and automatically swing wide open, and remain open until either the alarm stops or the close button is pressed and held for 3 seconds. When the door is in the alarm condition, it will not automatically lock upon closing, regardless of the position of the toggle switch. It can still lock, but only by pressing the lock button on the inside with the door closed, or by entering the code on the outside, again with the door closed. This prevents accidentally locking yourself or other people out in the event of a false alarm, as well as allowing the fire department to enter if there's a real emergency.

I know that one could probably build a system like this with the right equipment and the ability to program such things, but the idea here was to make a control box, keypad and door opener that are designed to work together and can do all this stuff already, without requiring special programming or additional pieces of electronics (except for of course a fire alarm) and all you need is a simple electric lock to complete the system, without additional features that many keypads have that you may not really need that tend to increase the cost of the keypads. One may want to have a locksmith do the actual installation of the door opener and lock, but interfacing this with a fire alarm is easy. If it's not a central system with an output, or running the wires is too much work, the system can be set up to listen for the sound of the fire alarm.