BATTERYLESS LOCKS

Security Devices for Access Control Which Generate Their Own Electricity

Martin Nunuparov, PhD,
Microelectronic Technology  Lab,
General Physics Institute
Russian Academy of Sciences

Kim Bowers,CML,
Advanced Security Concept,
www.mediasafe.com

Three important trends in intelligent access controls for turn-of-the-century security systems may be identified as:

2. Functional autonomy. (Can Function Independently When Required)

3. Power Supply Independence. (Dependability, Invulnerability to Outages)

The first allows any electronic systems to be controlled and monitored from a central host computer, the second simply means that even if external and/or reserve power or communications fail the security components continue to function on their own autonomously without external intervention. True autonomic systems, whether networked or stand-alone, will eliminate problems associated with power loss or failed batteries and their subsequent loss of security protocols.

Far from being mutually exclusive, all these critical design characteristics may now be realized simultaneously in a dramatic new way while also achieving a fourth market demand, a convenient user interface, with the standard popular electronic features. Chief among these new methods and strategies is the complete elimination of the need for batteries or hardwiring, stepper motors and electomagnetic mechanical components.

The origins of electronic access control systems in the era of the component approach to electronics meant that they were comprised of physically separate devices such as an electro mechanical device, a CPU, a power supply, digital keypad or card reader, perhaps a standard mechanical lock, a door position sensor and a battery backup.

4. Yet another market demand has been to consolidate these components whenever possible into self contained, compact units which appear and function more like standard door hardware. This makes the user interface more intuitive, convenient and aesthetically appealing.

The relatively recent introduction of cost-effective, stand-alone, self-contained, electronic door locks has met with considerable success. Through these slimmed-down products the familiar advantages of the more cumbersome and costly component package systems have been introduced to new markets which now are rapidly expanding as the products themselves continue to further evolve.

Aside from the further refinement of their operating systems, increasing the units' overall reliability and gradual cost reduction,where might this technology headed next?

According to our vision of the EAC market the next step in the development of this exciting field can now be clearly discerned.

So far, the only company to enter the autonomous electronic stand-alone field had been Mas-Hamilton. Through that company's innovative use of a stepper motor and some good engineering work, they produced a lock which rewrote the General Service Administration's specifications for U.S. Government security containers.

Because conventional dial type combinations on safes and vaults have always had the traditional user interface problems associated with rotating wheel pack combination locks, market reception was relatively forgiving for the X-07's difficult dialing procedure. It might also be said that "high security market" acceptance of the user interface was accomplished in some measure simply because no one else had yet come up with another high security alternative to compete or to compare it with.

Mas-Hamilton's new stepper-motor door hardware leaves much to be desired in its cumbersome user interface, high cost and unesthetic design.

The set of innovative solutions to the autonomous electronic objective takes a radically different and elegantly simple technological route. The stand-alone technology he has devised utilizes neither a stepper motor for power, an electromagnetic solenoid or electro-motor for locking and can be miniaturized to the point that it will even fit into a lock cylinder for powering electronic recognition and autonomous transaction logging in integrated systems. An uncomplicated and economical piezoelectric crystal like the one used in familiar kitchen lighters instantly produces in the neighborhood of 1000 volts. A CMOS microchip operates on around 6 volts. The challenge set out to master was to render this brief pulse of power into a form which was not only usable to identify the qualifying code, key or combination but also to operate the locking and unlocking mechanism as well.

Some others have tried for years to accomplish this feat, but they have all used basically the same approach, direct conversion of the piezoelectric charge to low voltage for processing by the microchip and for operating a conventional electromagnetic solenoid or electro-motor for activation of the physical locking device.

Rather than the kind of current used by all other systems, the Piezo Power Supply operates on the basis of electro-adhesive forces, eliminating the power conversion problem. Following is a brief description of the Piezo Power Supply / Chiplock technology, its market advantages and basic functionality.

Currently electronic locks are characterized by five common, operative components including:

2. an electronic decoder, or qualifying device which determines control and access levels,

3. an electro mechanical device which, upon activation by the decoder, de-blocks or activates the mechanical locking device and

4. the lock mechanics, which allows passage through the controlled opening upon qualification via the lock's power and control components.

5. battery back-up power

Power Supplies and Energy Consumption

The primary consumers of energy in these locks are the decoder (and primarily) electro-mechanical unit. Coupled with the limited standard shelf life of batteries, this power consumption renders most existing electronic locks somewhat "power supply vulnerable" by design and demands periodic attention and maintenance to ensure reliable operation.

As follows, we evaluate how long standard low-voltage batteries with charge capacity of 100 coulomb (approx. 0.027 amp. hours) are able to supply power to the lock.

The energy consumption of the lock's decoder, based upon a CMOS chip, is negligible - about 0.00001 coulomb. This allows school calculators to work for several years with one battery and practically forever with auxiliary assistance from a photovoltaic element (a silicon solar cell). However, when we turn to evaluating the consumption of common electro mechanical devices used in locking mechanisms, such as electromagnets or electro motors we find much room for innovation and improvement.

In order to obtain a mechanical force equivalent to about 10 grams which is needed during the deblocking or unlocking time of 5 seconds, it is necessary to provide electric current through electromagnetic coils of no less then 0.01 amps. which results in a total charge consumption from the battery of 0.05 coulombs.

We may conclude that a single battery will be able to support only 100/(0.05+0.00001)=2000 acts of unlocking the locks. This result is not far from the reality, and requires that much more substantial power must be held in reserve than would be required for simply operating the mechanics through their functional cycle one time. But regardless of the extended life of the batteries (up to as many as 80,000 cycles according to current published data) the reserve life of independent or "stand-alone" battery operated locks means that the batteries still must be replaced periodically or the locks will fail to function reliably. Hence, complete independance from outside power supplies, or functional autonomy, has not been achieved by battery operated locks.

 Beyond batteries, hardwiring, and generators

Some years ago, this basic idea was ingeniously developed by Mas-Hamilton whose designers exploited the principle of electromagnetic inductance. By means of manual (rotary) manipulation of a stepper motor an electric charge is accumulated on the windings of the motor stator. However, due largely to the conventional electro mechanical activator utilized in the Mas-Hamilton lock, with its inherent inefficiencies as shown above, it is necessary to turn the dial repeatedly, making this a separate step in the operating procedure, in order to achieve sufficient power to energize the lock. This method is somewhat expensive relative to the cost of mechanical combination locks without appreciably improving the user interface.

We believe that the transformation of mechanical energy to electrical power can be made in another, more simple and economical manner - by means of piezoelements. Their utilization effectively eliminates not only the battery, but also the additional steps in the user interface which are necessary to generate electrical power. Physical pressure on piezoelements causes electrical charge to be produced instantaneously, and while there is a very small electric current produced, the piezoelement produces an electrical charge of about a thousands volts. Familiar devices which use piezoelements include common available piezo-lighters, where the piezoelectric charge reaches breakdown voltage and causes an electric spark to ingnite the lighter's fuel.

Thus, by means of a piezoelement we can quickly and effectively convert mechanical energy into the form necessary to charge a capacitor. For example, the energy from the single spark of electricity produced by piezolighters such as those known by the names, "CRICKET" or "BiC" is about 0.001joules. We have demonstrated that this energy can be stored in an electrical capacitor of 100 microfarads with 5volts or 0.0005 coulomb. To achieve this critical conversion a certain amount of innovative "know how" is required by the electrical engineer since he needs to reduce the potential of piezocharges from a thousand volts to only a few volts suitable for the micro circuitry of the CMOS chip. Up until the demonstration of our methods, this challenge has been one of the insurmountable tasks facing those who have attempted to make a practical piezo-electronic lock.

Another problem then had to be solved. As one might have gleaned from the above analysis, a piezoelement which produces 0.0005 coulomb of electricity would not operate traditional electromagnetic (solenoid) locks which require 0.05 coulombs. Thus to employ piezoelements as a feasible power supply, we had to develop a new class of electromechanical units with much greater efficiency than the electromagnetic types thus far employed in the industry.

Our CHIPLOCK device is the best and only method yet to achieve the levels of reliability, efficiency and simplicity necessary for truly user-friendly autonomous access controls.

CHIPLOCK concept 

CHIPLOCK is our new electrostatic blocking unit for locks and other servo-mechanical devices (robot manipulators, valves, etc.) which can be reliably activated by means of a very small electric charge.

CHIPLOCK is composed of a static box and movable bar which may be fixed in at least two positions, and used as a "dogging device" or "trigger" for lock mechanics.

CHIPLOCK action is based upon internal electroadhesive forces, derived by a very small electric charge (about 0.000001 coulomb) which is injected into the CHIPLOCK unit. After being charged...

CHIPLOCK produces a mechanical force (up to 500 grams), which immobilizes the 'dog' in its required position.

CHIPLOCK, as compared to conventional electromagnetic solenoids and other electro mechanical devices, does not require a continuous power supply, and can be completely disconnected from power after being charged.

CHIPLOCK consumption of electricity is evaluated as 50,000 times less than that required for electromagnetic solenoid locks, so it is a most attractive feature for reduction of a lock's power consumption.

CHIPLOCK can be charged by means of a wide variety of charge generators. Among the most suitable generators are piezoelements. Piezoelements also have the additional advantages for utilization in locks, due to the convenience of exploiting human mechanical energy expended during a lock's normal operation (like the turning the locks handle, or inserting of a plastic card, or the pressing of the buttons of a digital keypad). When one thus applies very slight pressure to the piezoelement it generates an electric charge which can then be injected into the CHIPLOCK unit making it active. Then, by means of a very small electronic signal from the decision making micro-controller (or decoder) CHIPLOCK can fix, or release the locking mechanism.

Our prototypes have shown the practicality of using the energy developed by a piezoelement through a single phyiscal action to reliably power the CHIPLOCK mechanics as well as the electronic decoder without the need for any external power supply or battery reserve.

We have now produced fully opperational prototype electronic locks which combine the advantages of electronic controls [non-volatile memory, complete stand-alone operation and a simple (user-friendly) user interface].

Autonomous locking with CHIPLOCK presupposes changes in new lock construction.

It should be noted that the application of CHIPLOCK electromechanics in the similar application of Mas-Hamilton's inductive lock has been publicly demonstrated by us to make it possible to reduce multiple turns of a dial to one brief movement like the pressing of the buttons of a keypad or the turn of a handle.

The significant conclusion for the security equipment marketplace which can be made from appearance of the combined PIEZO POWER SUPPLY & CHIPLOCK electromechanics - PIEZOLOCK systems utilizing CMOS chip technology with nonvolatile memory is that it is now possible to eliminate altogether galvanic power supplies and produce practical and economical autonomous lock systems for a wide variety of commercial, residential and automotive applications.

For some applications where complete piezopower is not necessary we plan to apply the piezoelement only for the CHIPLOCK mechanics, and small lithium backup battery 1.5-3 volts (with 10 years lifetime) for electronic controller. This method will dramatically extend the practical life of batteries, since microcontrollers use far less energy than electromechanics.

CHIPLOCK is a flexible concept for a locking device and can be made in various configurations suitable for any construction of locks from large, to miniature mechanics, for door locks, lock cylinders, safe locks, car locks, padlocks etc.

CHIPLOCK is highly advantageous in the application of autonomous electronic locks, where it dramatically demonstrates its advantage vs. electromagnetic locks which require batteries.

The PIEZOLOCK concept can be very effective for retrofitting in most mechanical locks.

Newelectro mechanics can be realized in various constructions. Up to this point we have demonstrated the following prototypical applications of piezolocks in international exhibitions:

- batteryless door locks with coding from plastic access cards, where the piezoelement produces required electricity derived from one turn the handle of lock, the insertion of the card into the reader or the introduction of a key into a cylinder.

- batteryless safe locks with coding from digital keypad and/or proximity / access card, where piezoenergy is obtained with a one quarter turn the dial or by means of other mechanical movements such as card insertion, key insertion or digital keypad entry.

- portable security applications such as padlocks, lock cylinders, locks for currency transport / money bags and courier pouches.

Perhaps the greatest application interest for the commercial market will be to use CHIPLOCK & PIEZO POWER SUPPLY applications to retrofit in mechanical locks adding to them the new smart properties of electronic locks.

At the International Fair, HANNOVER MESSE '97 we demonstrated the retrofit of piezo-activating latches into a mechanical lock from ABLOY, which upgraded the lock to operation by a second level of security via an access control card.

CHIPLOCK construction and the corresponding size of its incorporated components are quite small which lends itself immediately to miniaturization. We have also produced a prototype application for standard safe lock electro mechanics (using a LaGard lock) and are working on application to standard lock cylinders for interested manufacturers.

The next applications engineering task we are working on for CHIPLOCK miniaturization is to make an electronic cylinders with piezolock implementation. This design is among the most exciting and offers enormous marketability for retrofit, systems integration and value added components.

This construction consists in half of the components in the standard cylinder with traditional mechanics and half enclosed in the lock knob. Inside the knob or handle is placed the CHIPLOCK electro mechanical unit and mechanics of piezopower supply. When the user inserts the key into the outside cylinder door piezo-elements are engaged and produce electricity for the CHIPLOCK electromechanics. Then if the correct electronic code is entered via the external decoder and the correct key is being used, CHIPLOCK will allow the user to turn the mechanical cylinder. The standard electronic lock features may also be employed.

In addition to Piezo Power and Chiplock, batteryless remote controls have been developed and demonstrated. These developments, among others, herald a new age of self-powered electronic systems.