Access devices, including PiezoProx from Essex Electronics of Carpinteria, Calif., take advantage of the piezoelectric effort. Devices range from exit buttons to dual technology keypads and readers.
The increased availability of advanced encoding, encryption and identity systems can provide an unprecedented level of access control, audit capability and security within those premises where it is needed. Implementation of such technologies onto networks makes integration with local or remote control centers extremely simple, at least until it becomes necessary to actually permit entry through any form of physical barrier, be it gates, doors or filing cabinet drawers. That is because the locks on these physical devices simply are not clever enough.

Piezo technology has paved the way for a whole new generation of high-reliability, low power locks. By connecting access control and lock technology into the building’s LAN infrastructure, new locks can be added simply by plugging into the network, or logging them in on a wireless connection.

Active latch modules and mechanisms bring ultra low-power and networkability to electronic locks for higher security.

Locking islands

The evolution of these little locking islands means that it is a short step to adding a unique identifier to each lock. With this capability, it is possible to reconfigure spaces and their associated security at will. New developments in Internet technology have made it possible to Web-enable just about anything, making overrides and privileges easily adaptable from any location. This allows the access control manager to monitor and control (lock and unlock) every single lock over the network.

As the new lock is not only a reader but also a communicator, the access control manager will receive information such as who, where and when a door was tried or opened in real-time and can react accordingly. Also, in case of an emergency like a fire alarm or terrorist attack, he can hand over the full control of a building’s door entry system to the authorities.

Piezo technology is the perfect partner for biometric and other advanced validation technologies. One example is the replacement of all traditional handles with active handles in a small facility. At night, the doors are closed and each room becomes secure. In the morning one command calls them all to engage and behave like normal doors. By connecting the timing to the network, this can be done automatically.

Piezoelectric materials are not new, having been discovered in the 19th century, but recent developments have dramatically changed the potential they offer the security industry. Piezo ceramic actuators will consume just 2mJ. One joule is the work required to lift the mass of 102 gram (e.g. a small apple) for one meter. This low current of 2mJ is important because it allows these devices to receive their power over spare wires in the existing wiring on a company’s network, or the telephone line. A telephone line with its 48V supply can only deliver a very limited amount of current, too little for motors and solenoids in existing locks, but ample for piezo electric devices.

Several ceramic materials have been described

as exhibiting a piezo effect and can be part

of the module.

In difficult locations

The size and low power consumption of these devices also opens up the possibility for more locks in places where traditional solutions are too bulky or power-hungry, such as banks of lockers in schools and remote locations. For higher security it is also possible to put multiple locks around the part to be secured to interlock a mechanical system. A good example of this is the multipoint locks used in UPVC (unplasticised Poly Vinyl Chloride) doors. Adding locks at random locations makes it much harder for an intruder to locate and defeat them.

Where traffic is high and variable, such as in public buildings, this technology can be deployed with minimal disruption and can be used in conjunction with advanced recognition devices to create custom pathways through the building. Doors that were previously considered uneconomic to secure can now be locked and an exact correlation of the user made against time via an Internet connection. In areas of higher sensitivity, a keypad can be used in combination with SMS messaging to continuously vary the entry code so that users can be given very precise authority from a remote control center, without the need to enable and disable swipes or tags.

Piezo technology remains more costly, as it is not possible to take a traditional lock construction and drop in a piezo solution; and this has been a major barrier to adoption. It will also be more costly than a motor for single point applications running on mains power, but as soon as the installation moves to networks and remote power supplies the advantages of the technology become clear. Given that electronic access control will continue to become smarter and more integrated, it seems clear that the new generation of locks will rapidly augment and then replace more traditional approaches.

Sidebar: It’s Not Greek to Me

According to James Phillips of CTS Wireless Components, Albuquerque, the piezoelectric effect is a property that exists in many materials. The name is made up of two parts: piezo, which is derived from the Greek work for pressure, and electric from electricity. The rough translation is, therefore, pressure - electric effect. In a piezoelectric material, the application of a force or stress results in the development of a charge in the material. This is known as the direct piezoelectric effect. Conversely, the application of a charge to the same material will result in a change in mechanical dimensions or strain. This is known as the indirect piezoelectric effect. Several ceramic materials have been described as exhibiting a piezoelectric effect.