Piezo actuators enable frugal electronic lock

A new electronic lock designed and engineered in the UK boasts an extra-long battery life thanks to the use of piezo actuator technology.

New technology has become an integral part of daily life.

You probably have used the Internet to shop.

You probably have used a mobile phone to communicate with your friends or business partners.

But have you ever wondered why you still use a simple key to operate your locks?.

Imagine a receptionist sitting at a desk in London opening the door to a building in Bristol by activating a remote release switch or an office worker letting the plumber into his house from his workplace.

Just a future scenario or reality?.

Recent developments in the electronic lock segment have changed dramatically the potential locks offer for the building and security industry as well as the private home sector.

With the introduction of piezo technology locks have become very smart and sophisticated after years of stagnation.

The first mechanical locks, made of wood, were probably created by a number of civilisations at the same time.

Records show them in use some 4000 years ago in Egypt.

They were large and crude in design; yet their principle of operation was the forerunner of the modern pin-tumbler locks of today.

Fastened vertically on the doorpost, the wooden lock contained moveable pins or "pin tumblers", that dropped by gravity into openings in the crosspiece or "bolt", and locked the door.

The first all-metal lock appeared between the years 870 and 900 and is attributed to English craftsmen.

They were simple bolts, made of iron with wards (obstructions) fitted around the keyholes to prevent tampering.

There were few improvements in locking mechanisms.

Security depended on intricacies such as hidden keyholes, trick devices and complicated warding.

With the introduction of electronic locks this has changed.

Codelocks is a UK company established for 15 years, based in Headley, near Newbury, Berkshire, UK.

Codelocks specialises in the provision of stand-alone coded access control locks for commercial and domestic applications.

Its latest product is the Codelocks 5000 Electronic, an electronic lock designed and engineered in the UK for commercial buildings, schools and hospitals.

It allows greater flexibility and security combined with all the advantages of existing electronic locks.

The difference is it uses a piezo actuator, developed by piezo specialist company Servocell, for the first time in a stand-alone electronic lock and provides a battery life of over 500,000 operations.

This is approximately ten times more than a typical electronic pushbutton lock.

The reason for this increase is the low power consumption.

The new piezo latch mechanism requires just one-sixtieth the power of a solenoid driven clutch mechanism.

Piezoceramic actuators will consume just 2mJ.

This low energy 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 piezoelectric devices.

"Apart from the huge benefits of low power consumption, the reliability and durability of the Servocell piezo actuator make it an ideal choice for the future development of electronic stand-alone access control".

"It has allowed us to develop a state-of-the art stand alone electronic lock within 18 months", explains Grant MacDonald, Managing Director Codelocks.

To achieve this sort of reliability and repeatability would normally require mains power linked to each lock.

This can be hugely expensive and the wiring gets bulky and complex very fast.

With this new technology locks can be powered over an existing Ethernet network or telephone cable, which significantly lowers the installation costs.

In addition to the power supplied by the network connection, each lock can also be controlled over the same network.

This allows the access control to be outsourced to any convenient point further reducing the costs to manage a building.

The advantages are obvious.

Every person's access is controlled and also limited to particular parts of a building such as a specific floor or merely reception without the inconvenience of going outside to grant access.

In addition, a mechanical key override guarantees access in the event of power supply failure.

There are only a few moving parts in the piezo actuator so the durability is much longer with no noticeable wear after 1.5 million cycles.

The Codelocks 5000 Electronic can have up to 90 different user codes and has 12 programs, all driven by a master code via the keypad.

These programs give the lock a wide range of access control options from installing new user codes, suspending and re-instating single user codes, suspending all user codes or to having a one-time user code.

A remote release switch, allowing a receptionist to open the door once a hardwired contact has been pressed, can activate the lock.

There is also an emergency mode setting to enable free access, when a connection is made via an alarm system.

Piezoelectric materials were discovered in the 19th century, and are now widely used in many devices such as most battery operated smoke detector alarms, fish finders, some cigarette lighters and many gas grill igniters.

Permanently polarised material such as quartz (SiO2) or barium titanate (BaTiO3) will produce an electric field when the material changes dimensions as a result of an imposed mechanical force.

These materials are piezoelectric, and this phenomenon is known as the piezoelectric effect.

Conversely, an applied electric field can cause a piezoelectric material to change dimensions.

This phenomenon is known as the reverse piezoelectric effect.

Servocell has harnessed the effect and created a series of modules that can be used as, for instance, an actuator for locks.

As soon as the installation moves to networks and remote power supplies the advantages of piezo technology are paramount.

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 the more traditional approaches.

"The innovative piezo technology is also the perfect partner for biometric and other advanced validation technologies to combine with stand alone locks due to its low power requirement".

"It promises to bring increased opportunity for access control", says MacDonald.

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