GB2026081A - Numerical, magnetically-encoded, electronically-sensed key - Google Patents

Abstract

A cylindrical key has one or more small magnets 18 embedded in certain specific locations and the associated key well receives the key and is provided with a plurality of sensors 15 which are Hall effect devices and which change their electronic state in the presence of a magnetic field. This means that each key can be individually coded. The sensors are interfaced with desired electronic equipment so that although each key appears identical, use of the key may record for example, the operator, and the dollar amount if used with a cash register, the amount and type of wares if used in a vending machine, the amount and identity of the operator if used in a photocopy machine, the time if used with a security checking device. These are examples only of the use of the device. <IMAGE>

Description

SPECIFICATION Numerical, magnetically-encoded, electronically-sensed key This invention relates to new and useful improvements in numerical, magnetically-encoded, electronically-sensed keys.

There are many situations where conventional keys and locks are used in which heavy usage and associated key wear makes them undesirable.

For example, cash registers where personell as well as the dollar value must be recorded and in security areas where personnel and times must be known.

Another example is in the use of a machine such as a photocopier used by several different people and in which it is desired to record the number of copies to each and to identify the user.

Another example where similar type information may be required includes vending machines, telephones and the like.

Many devices utilize electronic means to record the various items of information together with keys such as brass keys to actuate same but conventional brass keys not only wear themselves and the lock but also shed metal particles due to constant use, which can interfere with sensitive electronic equipment.

Also conventional keys and locks are readily forced, particularly when worn, so that jamming of the mechanism often occurs under these conditions.

Various magnetically operated programming or lock devices are known. For example, U.S.

Patents 35069393, 3633393, 3919869 and 3444711 all illustrate and describe such systems inasmuch as they all use magnets as an encoding method.

However, all of the four above mentioned patents rely on the mechanical movement.

Even the first one uses a magnetically operated, but mechanical read relay for decoding and uses mechanical movement to close electrical contacts rather than a mechanical latch or lock shown in the other three U.S. patents.

One of the essential differences between the present device and prior art is the fact that in the present device, no mechanical motion exists in the encoding or decoding technique inasmuch as it is purely an electronic action with the exception of the original insertion of the key into the key well.

The present invention overcomes these disadvantages by providing a key device comprising a key well component having a key well defined by the walls of an aperture within the component, and a key component slidably engageable within the key well, means to orient the key component within the key well, a plurality of sensors in the key well component operatively adjacent the wail of the key well, said sensors taking the form of Hall effect devices, and at least one magnet which is operatively aligned with one of the sensors when the key component is inserted within the key well.

Preferably said at least one magnet is embedded within the body of the key component.

Advantages include the fact that all keys may appear physically identical and that a single key well may be used by all keys.

There are no moving parts inasmuch as no rotation is required and the keys have excellent resistance to demagnetization.

The key well component is easily constructed so that it may be open on, for example, three sides at the inner end so that foreign materials do not clog the operation.

Activation of the system may be arranged to occur when the key reaches the physical stop but activation is not dependent upon physical contact with the stop and the keys do not have to be interrogated in order for activation to occur inasmuch as interrogation of the key is automatic when the key is in place.

The key well sensors are not sensitive to strong, stray magnetic fields and the smooth physical shape of the keys makes them very easy to carry and to store.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is an isomatric schematic view showing one embodiment of the keys together with an associated keywell.

Figure 2 is a chart showing the binary code used in the present embodiment of the device.

Figure 3 is a vertical section along the line 3-3 of Fig. 4, of the preferred embodiment.

Figure 4 is a rear view of Fig. 3 with the end plate removed.

Figure 5 is a cross sectional view of the preferred key component.

Figure 6 is a fragmentary isometric view of half of the key component prior to assembly.

Figure 7 is a plan view of the preferred key component broken away in part to show the interior thereof.

Figure 8 is an end view of two key component halves prior to assembly.

Figure 9 is an isometric schematic view similar to Fig. 3, but showing the key component displaced from the key well component.

Figure 10 is an isometric schematic rear view of the key well component with the back plate spaced therefrom.

Figure 11 is a schematic view of the magnets and sensors representation of the magnetic/sensor configuration.

Figure 12 is a schematic diagram of appropriate electronics to eliminate or cancel the problem of a large differential sensitivity.

Figure 13 is a schematic diagram of an alternative circuit.

Figure 14 is a longitudinal section of an alternative embodiment of the device.

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION Proceeding therefore to describe the invention in detail, reference character 10 shows one embodiment of the key well which includes a longitudinally extending key receptacle 11, the dimensions of which are similar to the dimensions of the associated key or keys 12.

In this particular embodiment, the key component 1 2 is in the form of a cylinder having a longitudinally extending groove 1 3 formed within one wall and the receptacle 11 is also cylindrical and is provided with a longitudinally extending rib 14 which engages the slot 1 3 thus assuring correct orientation of the key 1 2 when it is inserted within the key well. If desired, the configuration of the key component and key well may be other than cylindrical as long as the key component slidably engages within the key well in a similar manner and means are provided to correctly orient one with the other.

It will be noted that three sides of the key well are open adjacent the inner end, indicated by reference character 14 thus assuring that the key well does not become clogged with foreign material during use.

A plurality of sensors 15A, 15B, 15C and 15D are provided within the structure 10 and take the form of Hall Effect devices which are well known devices which change their electronic state in the presence of a magnetic field.

The Hall Effect, in a few words, is the generation of a voltage across opposite edges of a thin electrical conductor carrying current when placed in a magnetic field. This voltage in turn is proportional to the current flowing through the conductor, its width, the type of material used, and the flux density perpendicular to the conductor. By holding three of these parameters constant (material, construction and current) Hall found that the voltage was directly proportional to the flux density or magnetic field.

Although four such sensors are illustrates, nevertheless it will be appreciated that any number may be provided depending upon the quantity of different and unique number required in any one set of keys. The present embodiment shows, as an example, an arrangement for a set of seven keys numerically coded for the numbers one through seven inclusive as will hereinafter be described.

The cylindrical key component 1 2 is preferably made from synthetic plastic and is provided with two or more miniature magnets embedded within the plastic in specific locations.

Firstly, one magnet 1 6 is embedded within the key 1 2 with its poles aligned along the axis of the key and this magnet is embedded just below the surface at the lower end or base 1 7 of the key.

One or more additional magnets 1 8A and 1 8B and 1 8C are embedded within the key 1 2 with their poles aligned perpendicular to the axis 1 9 and their locations are chosen to align with the aforementioned key well sensors 15A, 15B and 15C.

As mentioned previously, the number of magnets is determined by the quantity of different and unique numbers required in any one set of keys. As an example, for a requirement for a set of seven keys numerically coded for the numbers 1 to 7 inclusive, the number of magnets arranged as a binary code could be used as illustrated in Fig. 2 where X denotes a magnet location.

For a binary code A = 1, B = 2, C = 4.

When electronically decoded, the value is the sum of a + B + C.

However, it will be appreciated that this can be extended indefinitely to cover any quantity of required numerically encoded keys and it should also be noted that although in this example, the three magnets 18A, 1 8B and 1 8C are in the same plane, nevertheless they could be in different planes providing the sensors 15A, 15B and 15C are in similar planes.

The sensors 15A, 15B and 15C (or as many as are required to develop the required quantity of different numerical code/numbers) are activated by the presence of the key magnets 18A, 1 8B and 18C, etc., when the key is fully inserted within the recess 11.

The sensor specifically designated 15D at the base of the key well is activated by the close presence or proximity of the magnet specifically designated 1 6 and this may be used to operate auxiliary electronic circuitry which applies activating power to the other sensors 15A, 15B anob 15C.

The change of state in the sensors 15A, 15B and 15C, etc., when in the presence of a magnetic field, is sensed by auxiliary electronic or electric circuitry (not illustrated) which is designed to trigger and buffer to the appropriate interface or direction connection, in order to operate other external machines, drawers, computers, recording devices, solenoids, or whatever physical, mechanical or electrical operation is required. However, as such devices are well known, it is not believed necessary to describe same further.

One typical application which should not be considered limiting, is cash registers where the identification of the person as well as the dollar value is required to be recorded.

As an example, in a location where a plurality of waiters operate one cash register, it is desirable that a record be made each time the cash register is operated, as to who the waiter is and how much has been punched into the register and if each waiter has been provided with his own key, it is relatively easy for this to be translated to a printed tape for subsequent checking and record keeping.

Another area in which such a device is useful is in a security area where the personnel and time of entry or exit must be known and recorded.

Photocopying machines and vending machines are other suggested uses. In the former instance, it may be desirable to record who uses the machine together with the number of copies. In the case of a vending machine, who used it, what was vended and the amount may be required.

The device is useful in all applications where heavy usage and associated key wear makes a conventional lock undesirable and also in all applications where a single key well must be used but where many different keys are required to identify the person using the lock and the time of such use, together with any other desired information.

Where many access locations are required, the specific key wells can be made to record the point of access as well as by whom and what time such access is made.

Dominant features include the fact that all the keys appear physically identical and that a single key well may be used by all keys without any moving parts apart from the simple sliding engagement of the key within the key well.

It should also be stressed that the keys do not have to be turned for activation thus reducing wear and that activation of the system occurs when the key reaches a physical stop, namely the lower end of the key well, but that such activation is not dependent on physical contact with the stop but rather with the proximity of a magnet which causes the necessary activation.

Proceeding next to describe the preferred embodiment illustrated in Figs. 3 through 13, a key well component is provided collectively designated 1 9 together with a key component collectively designated 20.

The key well component 1 9 includes a rectangular mounting flange 21 having pins 22 extending rearwardly therefrom for engagement within apertures in an equipment panel or the like (not illustrated) to which the device may be secured by conventional fasteners such as Tinnerman (trade mark) nuts.

Other methods of securement can, of course, be used.

A substantially cylindrical body portion 23 extends rearwardly from the mounting flange 21 and this body portion is longitudinally apertured as at 24 to form a key well 25 adapted to receive the key component 20.

Although the preferred configuration of the key component and the key well, is cylindrical, nevertheless it will be appreciated that other cross sectional configurations can be used such as rectangular, triangular or the like.

The rear portion 26 of the body portion 23 is cut away and communicates with the inner end of the key well 25 so that any liquids or debris which may inadvertently enter the key well, are displaced through this area 26 thus preventing the key component from jamming when it is entered into the key well 25.

Longitudinal recesses or cavities 27 are formed in the body portion 23 parallel to but spaced from the key well 25 and a circuit board 28 is adapted to be inserted within either one of the cavities with the edges of the board engaging the longitudinally extending grooves 29 at each side of the cavities. The circuit board carries the necessary printed circuit material (not illustrated on the board) together with a plurality of sensors S1 through S6 which are operatively connected to the key board and supported at the base of the cavities in close proximity with the wall 30 of the key well.

Once the printed circuit boards are in circuit, the cavities may be filled with a potting material such as silicone or the like. This not only retains the circuit board in the desired location, but also insulates same against vibration and possible damage.

The sensors S1 through S6 (in the present embodiment) take the form of Hall Effect devices similar to that hereinbefore described.

Electrical connections 31 operatively connect the circuit board with a source of electrical energy, for example battery 32, and through the necessary interfaces (not illustrated) to electronic assemblies 33 shown in block form in Fig. 3. The electronic assemblies, of course, will vary depending upon design parameters and the use to which the device is being placed.

Means are provided to orient the key within the key well 25, said means taking the form of a longitudinally extending rib 34 extending inwardly from the wall of the key well 25 and extending from adjacent the inner end 35 of the key well to a point 36 along the length of the key well but terminating short of the entrance 37 which, in this embodiment, is chamfered as at 38 to facilitate engagement of the key component 20 therewithin.

The key component is provided with a longitudinally extending groove 39 extending from the inner end 40 thereof to a point 41 along the length thereof spaced from the outer end 42 and the length of the groove 39 and the rib 36 is such that when the key component is fully inserted within the key well, the inner end 40 of the key component is in close proximity to or just in contact with the face 43 of a further sensor 44 within the end cap 45. This prevents the key from being rammed into the key well with sufficient force and movement to damage the end cap assembly 45.

It should be noted that the key well component is preferably on a sloping face of the equipment panel or is positioned so that mounting flange 21 is substantially horizontal.

This means that the key component 20 is merely dropped into the key well 25 and rotated lightly until the groove 39 aligns with the rib 34 whereupon the key component drops the full distance limited by the engagement of the rib to the groove and with the inner end 40 of the key component in the aforementioned close proximity to the sensor 44.

This sensor, in this embodiment can be utilized to ensure that the circuitry does not operate unless the key is fully inserted in order to preserve the integrity of the entire system. It is also a Hall Effect device and it is actuated by a small magnet 1 6A similar to magnet 1 6 described in the previous embodiment. The end cap 45 is secured to the rear end of the body portion 23 with locating pegs or extensions 46 and may be secured by means of set screws (not illustrated) or the like engaging through drillings 47 and into screw threaded drillings 48 within the rear end of the body portion (see Fig. 10).

The preferred embodiment of the key component 20 is preferably made in two longitudinal halves 20A and 20B with mating planar surfaces 49 and location pins 50 extending from one of the mating surfaces 49 engageable within drillings 51 within the other mating surface.

A plurality of cavities collectively designated 52 are formed in the two halves, each cavity in each half consisting of an upper and lower shallow portion 53 and a central deeper portion 54 into which the small magnets M1 through M6 may be inserted.

These magnets may be inserted so that they lie along axis AD (see Fig. 5) or axis BC, depending upon the coding required. When the necessary magnets have been inserted within the respective recesses, the two halves of the key are engaged together with the pins 50 engaging the drillings 51 and permanently secured together by an adhesive (not illustrated) or other similar means so that the cross sectional configuration of the key component is as shown in Fig. 5 with the parting line being along axis AD or BC, depending upon constructional choice.

It should be noted that at the same time that the magnet M1 through M6 are inserted, magnet M7 is also inserted with the longitudinal axis thereof lying parallel to the longitudinal axis of the key component. The longitudinal N/S axes of magnets M1 through M6 are, of course, perpendicular to the longitudinal axis of the key component as in the previous embodiment.

In the present embodiment, two sets of key well electronics may be utilized. One is for the limited seven-key maximum system and the second is for a 64-key maximum system.

Dealing first with the seven-key maximum system, reference should be made to Figs. 11 and 1 2. If the magnetic/sensor configuration of Fig. 11 is utilized, it generates a three-line binary code (1, 2 and 4) for a total of seven keys numbered 1 to 7 inclusive similar to the first embodiment hereinbefore described.

A Hall Effect sensor has a characteristic (as do all magnetically operated devices) called differential sensitivity. What this translates into is that while it may take 300 magnetic units to operate the device (switch it on), it will not de-activate (switch off) until the magnetic field is reduced to say 100 magnetic units.

This means that the key must be pulled from the key well is a fixed distance before the bottom sensor S7 de-activates. If this distance was such that it is the same distance between two magnet-sensor locations then a different code could be generated (different in the sense of a number other than the one that the particular key is designed to denote).

Using Fig. 11 as an example, key number 7 above uses all magnet locations (M1, M2 and M3) shifting the key a distance between the sensors (i.e. removal from the key well that distance) would, as long as magnet M7 is still activated, generate the number 3 (M3 = binary 4 would no longer be activated).

The same problem would exist if the magnets were made too large (physically and in magnetic strength).

Obviously, the size of the magnets, choice of sensors and the spacing of the magnets/sensors must be chosen carefully in order to obtain the most reliable results. The circuitry of Fig. 1 2 can be utilized with a 7key system, for example.

The 4071 is an industry standard Quad 2 input OR c-MOS digital gate and is well described in the literature. The same is true of the linear LM3900 quad op-amp.

The output of each of the three sensors is connected to one input of one of the OR gates. If the end sensor (activated by the end magnet M7 when the key is fully inserted) is not activated its positive output forces the outputs of all three OR gages to positive which is transmitted non-inverted to the output of the LM3900 buffers. This generates code zero for negative logic number systems.

When the key is fully inserted, the output of the bottom sensor is zero and the outputs of the OR gates assume the state of the sensors.

This is transmitted through the LM3900 to the outputs.

If the LM3900 is rewired for an inverting operation all code lines will be inverted such that code zero will generate all zero's at the output and will be read as a zero for positive logic number systems.

The choice of non-inversion was made to make the system directly compatible and a direct replacement for existing clerk push button switches on existing cash registers. A small PC board inverting interface (not illustreted) is used for installations where positive logic is employed.

In order to squeeze down or reduce the spacing in order to minimize the length of the key, particularly when a larger number of keys may be used as in the present embodiment, the electronic shown in Fig. 1 2 may be used.

If the construction of the preferred embodiment is used for a seven-key maximum sys teni, the differential magnetic sensitivity is over a distance of slightly less than half the space between the magnets/sensors, so that the problem does not lead to the generation of false codes.

However, if all magnetic locations are used to generate one to sixty-three different codes, then the distance between magnets/sensors is reduced by half and it is possible that if all tolerances fall in one direction, careful removal of the key could generate a different number.

This is resolved by the circuitry of Fig. 1 3.

The 41 74 and 4528 C-MOS digital intrgrated circuits are industry standards and are well described in the literature.

The 41 74 device is a HEX (6 bit) strobed latch / memory.

The 4528 is a dual monostable multivibrator.

When the pin 9 of the 41 74 is kept at logic zero, the output lines are isolated from the input lines. When pin 9 becomes positive the output is effectively coupled to the input.

When once again pin 9 goes to logic zero the output data is retained and the outputs no longer follow the inputs. The application of a logic zero to pin 1 resets the outputs to zero regrdless of the states of the inputs. These two lines (inputs) are operated by the action of the 4528 device.

When the bottom sensor is activated (the complete insertion of a key) its output goes to logical zero. This causes pin 6 to go positive for a period of time determined by R1 and C1 and then return to zero. This latches the key code in the output of the 41 74. When the bottom sensor is de-activaged (removal of the key), it returns to logic one (positive output) which causes pin 9 to go to logic zero for a period of time determined by R2 and C2 before returning to positive. This resets the output of the 41 74 to zero regardless of the condition of the inputs.

The operation of this circuit guarantees that only the true code read on the initial insertion of the key can be read no matter what the level of the differential magnetic sensitivity of the sensors may be.

The grounding of pin 5 of the 4528 by the action of some external circuitry causes the output of the 41 74 to go to zero. This would be the normal action of the external power failure sensing circuitry.

An additional advantage for this approach is for those applications where the key well is used to record other information. As an example, in a photocopier application where the number of copies will be recorded along with who made the copies. This recording system contains an electronic memory which is protected by a battery back-up for up to two years on a power failure. This is incorporated in the photocopier circuitry and therefore does not form part of this application.

When power fails in any electronic digital circuit system, there can be no guarantee of the logic state that the individual logic circuits will assume, upon the return of power. Within the photocopier recording system or within any similar system that uses similar data retention techniques, there will exist circuitry to guarantee the return to the desired state when power is re-applied. The 64-key key well circuitry described in Fig. 1 3 allows a simple guarantee of a zero code by forcing the power circuitry to ground pin 5 of the SCL 4528 C-MOS IC simulating the complete removal of the key and generating a code zero. This will latch code zero into the MC14174B latch/memory forcing the operator to remove and re-insert the key.Obviously, without such a feature, the operator could wilfully generate some random false key code by removal and re-insertion of the power plug.

This approach, as mentioned previously, is unnecessary for the limited seven-key system since all applications utilizing such a limited sytem, include means to take care of power failure within the electronics of the device to which the system is attached. When utlizing the 1 to 64-key set, the eight non-compatible sets of keys (key set) is accomplished as follows: (See Fig. 3).

Magnets M1 to M6 can be oriented in either of the quadrants AD or BC.

Magnet M7 may be placed in any one of the four quadrants A, B, C, or D and sensor S7 is inserted into the molded end plate in the appropriate location.

If the full 6 binary lines are not used, the unused locations can be used to expand the number of non-compatible key sets.

As an example, with a 7-key system (3 binary lines) the three unused binary lines may be used to multipky the number of noncompatible key sets by a factor of 8 thus giving 64 sets.

As another example, with a 1 5 key maximum system (4 binary lines) the two unused lines can be used to multiply the number of non-compatible key sets by a factor of 4 thus giving 32 sets.

Obviously, combinations of orientations M1 through M7 could be used to scramble the code and more than one magnet in location M7 could be placed in more than one quadrant along with additional sensors S7 to generate another binary 64 line or to scramble the codes Finally, reference should be made to Fig.

14 which shows an alternative embodiment in which the magnets M1 to M6 are located in the body portion 23 of the key well component with the sensors S1 to S6 in the original location. The key component, in this embodiment, identified 20C, is provided with magnetic flux paths 55 perpendicular to the longitudinal axis and which can be covered by an opaque plastic sheet 56 so that they cannot be located. These paths 55 permitting the magnetic flux to pass from the magnets to the sensors.

Finally, it should be noted that the key component is preferably made from synthetic plastic and the key well component is also preferably made from synthetic plastic, together with the end cap 45.

Claims (11)

1. A key device comprising a key well component having a key well defined by the walls of an aperture within the component, and a key component slidably engageable within the key well, means to orient the key component within the key well, a plurality of sensors in the key well component operatively adjacent the wall of the key well, said sensors taking the form of Hall effect devices, and at least one magnet which is operatively aligned with one of the sensors when the key component is inserted within the key well.

2. A key device according to claim 1 wherein said at least one magnet is disposed within the key component.

3. A key device according to Claim 1 or 2 which includes at least one sensor operatively adjacent the inner end of the key well, and at least one magnet adjacent the inner end of said key component, the N-S axis of the magnet lying parallel to the longitudinal axis of the key component, the last mentioned sensor being operatively connected to a source of electrical energy and adapted to connect the source of electrical energy to first mentioned sensors when the key is fully inserted within the component.

4. A key device according to Claim 1 or 2 in which the N-S axis of said at least one magnet is perpendicular to the longitudinal axis of the key component.

5. A key device according to any one of the preceding claims in which said means to orient the key component within the key well includes a longitudinally extending rib on the wall of one of the components and a longitudinally extending groove in the wall of the other of the components, the rib slidably engaging within the groove when the key component is inserted into the key well component.

6. A key device according to Claims 1, 2 or 4 in which the lower side of adjacent the inner end of the key well component is open for the clearance of debris within the key well.

7. A key device according to Claim 3 in which the lower side of adjacent the inner end of the key well component is open for the clearance of debris within the key well, said sensor adjacent the inner end of the key well being on the side of said open inner end of the key well component remote from the key well.

8. A key device according to any of the preceding claims in which the key well component includes a circuit board recess formed therein parallel to the key well, but spaced therefrom and a circuit board supported within the recess, said sensors being operatively mounted upon the circuit board.

9. A key device according to Claim 8 in which the key component includes means whereby the first mentioned at least one magnet may be situated perpendicular to the longitudinal axis along a diametrical line of said key component or along another diametrical line at 90 to the first diametrical line.

1 0. A key device according to Claim 9 in which the key component comprises two portions split longitudinally, each of the portions including a magnet recess along one diametrical line and a further magent recess at 90 to said first magnet recess, the portions being fixedly secured together when magnets are inserted within the recesses.

11. A key device according to Claims 8, 9 or 10 in which the means to orient the key component with respect to the key well includes a rib extending longitudinally from the wall of the key well adjacent the inner end of the key well to a point part way along the key well, and a groove extending longitudinally along the wall of said key component and extending from the inner end thereof to part way along the wall thereof, to limit the depth of engagement of the key component within the key well whereby the inner end of the key component terminates adjacent to or in contact with the inner end of the key well when fully inserted therein.

1 2. A key device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.