Keep the lock, replace the tumbler

There are lots of electronic door locks available today but they all have the same problem. They are much larger than a typical mechanical lock and must have a power source.

There are two parts to an electronic lock. The key and the motor to open the bolt or lock itself. The key is typically a RFID badge, numeric code, fingerprint, etc. Then once the user is authenticated the lock has a motor that will open the bolt or unlatch the mechanism to allow the door to be opened.

Because of this there must be a battery for power and most of the time the entire door handle assembly replaced with something much larger. This is sometimes difficult and also more unsightly.

I propose a hybrid of an electronic lock that fits into the same small space as a mechanical lock while still maintaining the same dimensions of a circular tumbler assembly that fits in most door locks/knobs today. It can even continue to use the same old fashion key as a backup.

Simply have a key with an RFID chip on it that is a flat blade like a normal key but smooth on both sides and is a narrower width than a normal key. A normal key would line up the pins to allow the tumbler to be turned thus unlocking the door. The RFID key would also engage a mechanism that uses a very small amount of power that would allow the tumbler to turn regardless of the pins positions and allow the key to then turn and unlock the door.

The power can be from the key itself being inserted like a magnetic generator. If the lock needs extra power the key can be inserted and removed multiple times like a generator moving back and forth. This is used in many non-battery emergency flashlights.

The electronic locks can be programmed with a master key or a fob of some sort that will use a NFC type of setup from a smartphone. If there is an issue a normal key can still be used to open the tumbler providing access.

The unlocking of the bolt itself requires most of the power but since you are turning a physical key that part is done by the user. Thus eliminating a larger lock being needed to house a motor and gear assembly.