Piezo actuator offers secure future for electronic locks

A British firm has developed a piezoelectric-based lock actuator which, it claims, has many advantages over traditional solenoid or motor-driven actuators. The low-power piezo actuator is fast-acting, has a long life and resists vibrations and hammer attacks.

Most existing electronic locks use power-hungry solenoids to actuate the release mechanism. They draw current continuously and generate heat. The alternative motorised actuators are also inefficient, are vulnerable to attack, and can be slow to respond.

Harlow-based Servocell claims that its piezo-based Active Lock system is the world`s first robust, reliable and low-power alternative to the existing technologies. It uses a freely-moving spring-loaded plunger connected to a blocking arm. When the handle is operated in the normal, unpowered state, only the latch turns and the lock will not open.

Applying power causes the actuator to move by 2.5mm in less than 100ms, blocking the plunger. When the handle is operated now, the whole mechanism rotates and the lock opens.

The Active Latch consumes just 6mW per operation, making batteries a realistic alternative to mains power. There is no heat build-up and there is said to be no noticeable wear, even after 1.5m operations. The lock can controlled by a two-wire system, making it compatible with existing access control systems.

Servocell is part of PBT, a company founded in 1998 as a spin-off from the circuit-breaker developer, PowerBreaker. PBT specialises in piezoceramic actuation technologies, which it has alrready used in electrical protection and gas valve applications.