Electronic keypads have been used to control access since the late 1950s, when the Cypher Lock was developed for United States government installations. This prototype electronic pushbutton lock with separate logic controller eliminated the “key.” To gain access, the access code was entered into the five rocker switches. The correct code had to be entered in proper sequence. Each rocker switch was connected to a relay that had to be tripped in the correct order. Only if all of the relays trip in their correct order would the Cypher Lock will permit access.
Around the mid 1980s, after the computer revolution, keypads started becoming commercially available at reasonable prices. Keypads became incorporated into access control systems and standalone electromechanical locks.
It was during this time that cylindrical and mortise locks were commercially available with electric locking or unlocking. Previously, for their own applications, locksmiths made the electrically converted locks. For more than 30 years, Architectural Control Systems, Inc. (ACSI) has been modifying and producing electrified locking hardware.
Over the following years, keypads became available in a variety of configurations and functionalities for controlling access. Early keypads were equipped with the software and hardware necessary to operate the lock mechanism in order to control access. This type of standalone keypad was and is still used for single-door access control systems.
Keypads can also be equipped with minimal circuitry to be just a keypad that a user code is entered in order to gain access. They are commonly known as keypad readers. They can be for a single door or as part of a larger system or a system that has a separate database. These single entry point keypads do not contain a logic circuit board and depend upon additional software and hardware to perform the access control functions.
Note: All keypads have a circuit board that at a minimum changes each button press to an electrical signal (digitizes it into “1”s and “0”s).
A variation on the single entry point keypad is the multi-door keypad that can be wired to server or database in order to be part of a larger access control system having one or more keypads.
The standalone keypad (does not have to be connected to a database or internet) is self-contained, having a built-in logic board. These standalone keypads were originally designed for interior applications, having built-in NO/NC relays. When a button (key) is pushed, there is a connection to a momentary switch or a capacitance change in a non-mechanical capacitive keypad. When a programmed User Code is entered, the Fail Safe or Fail Secure electrified lock mechanism would either receive or have power eliminated, permitting access through the door. LEDs have been added to make programming and operation less complicated. Programming the standalone keypad is usually accomplished at the keypad.
The basic access control keypads vary by design and applications. For example, the standard commercially available keypads usually have a 12-button configuration, with three buttons side to side and four buttons up and down. Most keypads in the North American market look like a telephone keypad without the alphabet above eight of the numbers. However, this configuration requires sufficient width in order to have three buttons side to side.
For narrow stile aluminum door openings, or mullion equipped double doors, the mounting surface can be very narrow, so the number of buttons is usually two side to side and up to seven up and down.
Early standalone keypads performed just the unlocking function for a small number of users. The first keypads I remember buying were standalone models designed for interior application controlling a single door. These keypads contained the “brains.” They were programmed at the keypad using the pushbuttons and if memory serves, you could program maybe 10 to 20 User Codes. These keypads were 12volt AC or DC and they were equipped with a small relay. When a programmed User Code was entered, the keypad would unlock the electric strike or the electromechanical lock for a limited period of time, which was sometimes adjustable. When power was lost, so were the user codes.
Keypad-Free, Vandal-Resistant Prox Lock
The Securitron DK-26 is Securiton’s medium to high security keypad solution. The narrow keypad makes this system suitable for door frames with narrow frames. The basic system is comprised of a...