Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The present invention relates to a body of
magnetic material having a number of distinct magnetic
poles on a surface of the body. This application is
a division of Canadian patent application Serial No.
449,929 filed March 19, 1984.
One use of such a body is in a key intended
to move magnetic locking elements of a lock to respective
releasing positions determined by the magnetic field
of the key.
According to the present invention, there
is provided a body of magnetic material having a surface
with a plurality of distinct magnetic poles, the flux
density varying within each pole in a manner such that
the flux density has a relatively low value at a position
between two further positions within said pole, at which
further positions the flux density is relatively high.
The poles on the surface of the body may be
like poles and be surrounded by an area of opposite
magnetic polarity. There is preferably an area of
opposite magnetic polarity which surrounds and is common
to all of the distinct poles on the surface of the body.
In one embodiment the body of magnetic material
is elongated and defines a rectilinear central axis.
With this version the poles face away from the axis
in respective different directions. A first pair of
directions define at the axis a first angle and a second
pair of these directions define at the axis a second
angle which is substantially different from the first
angle.
The body may be incorporated in a magnetic
key and the key may be combined with a device which can
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be controlled by the key, the device having an
opening for receiving the body and a plurali-ty of
devices which are responsive to the magnetic field of
the key to provide an electrical output when the body
S is introduced into the opening. These devices may be
Hall effect devices.
The device combined with the key may further
comprise a plurality of locking elements which are
movable by the magnetic field of the key between
locking and releasing positions, a body and an
operating member which is movable relative to the
body, when the locking elements are in their
releasing positions, movement of the operating member
relative to the body being restricted or prevented
lS when the locking elements are in their locking
positions. Alternatively, the key may be engageable
with the locking elements to displace same to their
releasing positions. Examples of apparatus for
magnetising a body in accordance with the present
invention, of a key embodying the invention and of a
device controlled by the key will now be described,
with reference to the accompanying drawings,
wherein:
FIGURE 1 illustrates diagrammatically
magnetising apparatus;
FIGURE 2 shows a plan view of an electrical
conductor of the apparatus of Figure l;
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FIGURE 3 shows, on an enlarged scale, a
fragmentary cross-section of a magnetising head of
the apparatus of Figure 1 in a plane containing an
axis of the apparatus;
FIGURE 4 shows a side view of the key
magnetised in the apparatus of Figure l;
FIGURE 5 shows a perspective view of an
alternative form of magnetising head for use in
magnetising the ke~;
FIGURES 6 and 7 show respectively a plan view
and an underneath plan view of the magnetising head
of Figure 5;
FIGURE 8 shows a cross-section through a device
controlled by the key;
FIGURE 9 shows a cross-section on the line 9-9
of Figure 8; and
FIGURE 10 shows a cross-section on the line
lO-10 of Figure 8.
The apparatus shown in Figure l is generally as
described in W079/00639. The apparatus comprises a
support lO for a key 11, the support being rotatable
relative to a base 12 of the apparatus about an axis
13 which is normally upright in use. The support is
adapted to support the k.ey ll with a longitudinal
axis of the key coincident with the axis 13 and with
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the key being at a predetermined position along the
axis 13 relative to the base. The key may be as
described in W079/00639, except in respect of its
magnetic poles.
The apparatus further comprises two magnetising
heads, one of which, 14, is constrained against
rotation relative to the base 12 by a pin 15 and the
other of which, 16, is rotatable relative to the base
about the axis 13. The magnetising heads can also be
adjusted along the axis 13 relative to the base and
the key support 10.
Each of the magnetising heads comprises an upper
electrical conductor 17 of plate-like form and having
the shape shown in Figure 2, when viewed in a direction
lS along the axis 13. Each head comprises a lower
electrical conductor 18 having the same shape as that
of the conductor 17, except that a terminal portion
36 of the conductor occupies a different position
relative to the remainder of the conductor, so that
the terminal portions are spaced substantially apart
in the head. Between the conductors 17 and 1~, there
is a central magnetic conductor 20, also of plate-like
form and bearing on its upper and lower surfaces
layers of electrically insulating material 21 which
insulate the magnetic conductor from the electrical
conductors. An upper magentic conductor 22 is
spaced upwardly from the electrical conductor 17
by a further 1ayer of eiectrical insulation 23 and a lower magnetic conductor
24 is spaced downwardly from the electrical conductor 18 by a further layer
25 o~ electrical insulation. The conductors 17 and 18 are preferably formed
of copper, whilst the conductors 20, 22 and 24 are preferably formed of iron.
At a position remote from the terminal portion 19, the electrical
conductors 17 and 18 protrude beyond the magnetic conductor 20 and its
associated electrical insulation. Between the protruding parts of fhe
electrical conductors there is mounted a further plate of copper (not shown)
which is rigidly secured to the electrical conductors and connects them in
series.
There is formed in each of the electrical conductors 17 and 18, but not
in the magnetic conductors 20, 22 and 2~, a rectilinear slot 26 which
intersects a wider hole 27 through which there extends a fastener (not shown)
for securing the conductors and their associated electrical insulation
together. The magnetic conductors are formed with holes corresponding to
the hole 27. The slot 26 extends from a margin 28 remote from the axis 13
towards a concave margin 29 of the electrical conductor which is close to the
axis. The margin 29 is an arc of a circle and has a radius of curvature
substantiatly equal to the external radius of a cylindrical shank of the key
I l. Between the end of the slot 26 and the margin 29 there is a neck 30 of
the electrical conductor.
As shown in Figure 3, the thickness of the electrical conductor 17 is
reduced in the vicinity of the neck 3û so that the neck is spaced by an air gap
from the electrical insulation 23 associated with the upper magnetic
conductor. In a corresponding manner, the thickness of the conductor 18 is
reduced in the vicinity of the neck 31 of that conductor to provide an air gap
between the neck and the electrical insulation 25. As shown in Figure 3,
there are preferably also air gaps between the necks 30 and 31 respectively
and the adjacent layers 21 of insulation.
Over the major part of its length, the slot 26 has a width less than the
radius of curvature of the margin 29. Near to the neck 30, the width of the
slot is increased somewhat to form a part-circular portion 32 of the slot.
Between this part-circular portion and the neck 3û, the margins of the slot
are rectilinear and converge to a point, to define a V.
The periphery of the conductor 17 is defined, on opposite sides of the
arcuate margin 29, by respective rectilinear margins 33 and 34 which are
mutually convergent towards the margin 29 and are at least approximately
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parallel to respective limbs of the V defined by the margins of the neck 30
which face the slot 26. The margins 33 and 34 may extend to the arcuate
marain 29. However~ as shown in Figure 2, there is preferably between the
margin 33 and the margin 29 a further, rectilinear margin which is set back
slightly from the margin 33 but is parallel thereto. Similarly, there is shown
between the margin 34 and the margin 29 a further rectilinear margin which
is parallel to the margin 34 but set back slightly therefrom towards the slot
26. As described in 1~/079/00639, the magnetic conductors 22 and 24
preferably have respective flanges which extend towards each other and lie
close to the margins 33 and 34. Air gaps remain between these flanges and
the neck 30, where the margins of the conductor 17 are set back from the
margins 33 and 34.
The shape of the electrical conductors shown in Figure 2 enables a large
electric current to be passed in close proximity to the shank of the key 11 at
frequent intervals without excessive heating of the magnetising head.
The arcuate margin 29 preferably subtends at the axis 13 an angle
which is less than 90, preferably in the region of 7û. In a case where the
radius of curvature of the margin 29 is approximately 2.5mm, the thickness
of each electrical conductor is approximately 2.5mm over the major part of
its area and is approximately l.9mm at the neck 30.
When an electric current is passed through the pair of electrical
conductors of the magnetising head 16, there is formed on the key 11 a
magnetic pole 35 having a shape which approximates to that of a square,
when developed onto a flat surface. A region of opposite magnetic polarity
results outside the square. By passing current through the electrical
conductors of both magnetising heads, there is formed at the same position
a1Ong the key two distinct magnetic poles having the same polarity and shape.
The magnetising heads may then be moved along the axis 13 relative to the
key to form further magnetic poles 36, 37 at a different position along the
key and poles 38, 39 at a further position along the key. Preferably, all of
the substantially square magnetic poles have the same magnetic polarity.
As shown in Figure 4, the key includes magnetic poles which face in
respective directions which are mutually inclined at an angle substantially
exceeding 0 but substantially less than 180. In the example illustrated, the
poles 36 and 37 are spaced from each other by 90, about the longitudinal
axis of the key, and are spaced from the pole 35 by 9û. The poles 38 and 39,
which lie at the same position along the key, face in respective directions
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which differ by approximately 135. The key illustrated has a cylindrical
shqnk. The key may be modified to have a shank of non-circular cross-
section, for example a hexagonal or other polygonal cross-section. In this
case, each magnetic pole rnay be formed on a flat face of the key shank.
There can be established on the surface of a key shank having a
diameter of Smm poles having a flux density of 375 gauss so that, at a
position near to the key shank and towards which the pole faces, the
magnetic flux density will be well in excess of 2ûO gquss and thus the
magnetic field of the key will be capable of operating a Hall effect device at
such a position.
The density of magnetic flux at each of poles 35 to 39 is such that these
poles can each operate a Hall effect device and produce an output signal
which is useful without amplification. By a Hall effect device, we mean an
integrated circuit comprising a volta~e regulator, a Hall voltage aenerator, a
signal amplifier, a trigger circuit and output transistors. This may be utilised in apparatus for identifying a particular key, where the apparatus defines a
passage for receiving q shank of the key and has a plurality of Hall effect
devices in predetermined positions along the boundary of the passage. Signals
produced by the Hall effect devices when the key has been inserted into the
identifying apparatus can be used to drive a standard integrated circuit
without prior amplification of these signals.
The magnetising head illustrated in Figure S comprises a single
electrical conductor 40 having three integral parts 41, 42 and 43 which are
spaced around an axis 44. The general shape of the conductor 4û is that of a
tube havins a taper at one end to define an internal space which is cylindrical
over a major part of its length and which tapers to a relat;vely small
diameter at one end. This space is occupied by an iron core 4S which is
electrically insulated from the conductor 4û. The core 45 occupies the
internal space substantially completely and has a circular tip 46 at its
tapered end.
Each of the parts 41, 42 and 43 of the conductor extends from one end
of the conductor to the other and presents a respective part-cylindrical
surface of smaller diameter towards the axis 44 and a further part-cylindrical
surface of larger diameter away from the axis. Between the parts 41 and 43,
there is a gap 47 which extends completely from one end of the conductor to
the other and is occupied by air or by material which 7s a better electrical
insulator than is air. Between the part 41 and the part 42, there is defined a
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slot 48 which extends from the larger end of the electrical conductor almost
to the smaller end thereof, leaving a neck 49 of the conductor between the
slot and a smaller end face 50 of the conductor. The slot 48 is of uniform
width along the major part of its length. Adjacent to the neck 49, there is a
wider part 51 of the slot. Preferably, the wider part is at least
approximately circular, as viewed in a direction towards the axis 44 and
perpendicular to the surface of the conductor 40 adjacent to the slot part S l.
Between the circular portion of the slot and the neck 49, the width of the slot
decreases gradually to zero.
Between the parts 42 and 43 of the electrical conductor, there is
provided a slot 52 similar to the slot 48. Between the slot 52 and the face 50,
there is a neck 53.
A magnetic conductor 54 (partly broken away in Figure 5) encloses the
electrical conductor 40 other than at its ends. The conductor 54 is
electrically insulated from the conductor 40 and supports the parts 41, 42 and
43 through the intermediary of electrical insulation.
The necks 49 and 53 lie at diametrically opposite positions with respect
to the axis 44 and present respective parts of the end face SO. This face is
arcuate, the centre of curvature Iying on the axis 44. The gap 47 subtends at
the axis 44 a small angle, typically 5. At the en-l face 50, the external
diameter of the conductor 40 is preferably within the range 3mm to 8mm and
the internal diameter of the conductor 40 is preferably within the range
û.Smm to 2.5mm. Typically, the external diameter of the conductor at this
face is 5mm and the internal diameter is I mm.
The magnetising head shown in Figure 5 is used in conjunction with a
support for a key. The magnetising head may be incorporated in apparatus
similar to that illustrated in Figure 1, in place of one of the magnetising
heads shown in Figure 1.
tlVhen the magnetising head of ~igure 5 is used, an electric current is
passed into the conductor 4û at the part 41 thereof, is conducted through the
neck 49 to the conductor part 42, is then conducted through the neck 53 to
the conductor part 43 and leaves the conductor 40 from the part 43.
Alternatively, the current may be passed in the reverse direction. A large
current flows through the necks 49 and 53 whilst these are adjacent to a
magnetising position on the surface of the key to be magnetised. There is
produced on the body of the key a magnetic pole which is surrounded by an
area of opposite magnetic polarity.
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The magnetic pole produced by use of the magnetising head shown in
Figure 5 may be substantially circular. The magnetising head of the
apparatus of Figure I may be arranged to ~orm a substantially square
magnetic pole on the key or, alternatively, an elongated pole having an
approximately rectangular shape.
The flux density oF the magnetic pole produced by use of the
magnetising head shown in Figure S varies from a low value at the centre of
the pole to a high value at a distance spaced somewhat from the centre of
the pole. The region of high flux density is substantially annular.
The device shown in Figure 8 comprises a body I lû which may be
secured in an opening in a door by means of a nut 111 which can be screwed
along an external surface of the body. The body 110 is hollow and there is
mounted within the body, for rotation relative thereto about an axis 112, an
operating member 113. The operating member also is hollow and defines a
central opening 114 for receiving the shank of the key shown in Figure 4. The
opening 11~ is lined by a tube 115 which protrudes beyond the operating
membér 1 13 in a direction away from an open, outer end of the opening 1 14.
The device of Figure 8 further comprises a sleeve 11 6 interposed
between the body 110 and the operating member 113. The sleeve and the
member 113 collectively define a number of paths along which respective
locking elements 117, 118 and 119 can move around the axis 112. Typically,
the path of eoch locking element subtends at that axis an angle of 6û.
Each of the locking elements 117, 118 and 119 has the form of a roller
arranged to roll on the external surface of the lining 115. Approximately one
half of the roller lies in a groove in the operating member 113 and the other
half lies in a groove formed in the sleeve 116. In the absence of a key, each
locking element normally lies in a locking position, in which it is trapped
between respective abutment surfaces of the member 113 and the sleeve 116,
these surfaces facing in opposite directions along the axis 11 2, so that
relative axial movernent of the member 1 13 and the sleeve 1 16 is prevented.
At one position along the path of each locking element, there is formed in the
corresponding qbutment surface of the sleeve 116 an opening into which one
half of the locking element can enter, when the locking element is in a
releasing position along its path, so that relative axiql movement of the
member 113 and the sleeve 116 is permitted.
The locking elements may be arranged as disclosed in GB 1,588,811 and
in GB 2,017,8û4.
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A pin 1 20 which is fixed in the body 11 0 protrudes into a camtrack
formed in the sleeve 116 to prevent rotation of the sleeve about the axis 112
relative to the body, unless the sleeve also moves axially. The operating
member 1 13 is restrained against axial movement relative to the body and is
keyed to the sleeve 116 to ensure that the sleeve rotates with the operating
member. Accordingly, the operating member can turn about the axis 11 2
only when each of the magnetic elements 117, 118 and 119 is in its releasing
position. The key is formed wlth magnetic poles at suitable positions to move
the locking elements into their releasing positions when the key is fully
inserted into the operating member. The key also has a lug for engaging in a
notch in the operating member to transmit torque to the operating member
for rotating same about the axis 1 12.
The device further comprises a number of sensors 121 capable of
responding to the magnetic field of a key, when the key is inserted into the
opening 114, by providing an electrical output. Each of these sensors is a
Hall effect device. The sensors 121 are mounted on a number of annular
carriers, ench of which is mounted on the exterior of the protruding part o-f
the sleeve 116. Typically, there are three such carriers, each carrying three
Hall effect devices. The carriers turn about the axis 1 12 with the operating
member 1 13.
Each carrier has, at one of its faces, a circular recess with an endless
row of teeth 129 near to the periphery of the recess. Each sensor 121 has an
arcuate row of complementary teeth. The pitch of the teeth is typically 10.
With this arrangement, a sensor can be fitted in its carrier at a position
around the axis 11 2 which is selected according to the position of a
corresponding magnetic pole on the key. In the particular example
illustrated, the recess in the carrier is occupied completely by three sensors
and the positions of the second and third of these sensors are determined by
the position of the first. Alternatively, a smaller number of sensors may be
provided in each carrier or gaps may be provided between the sensors on a
single carrier, so that the position of one sensor about the axis 112 can be
varied without varying the position of another sensor.
Each carrier preferably bears indicia for identifying respective ones of
the teeth 129. In a case where the sensors 121 are to be mounted on the
carrier by a person, these indicia may be in the form of numerals which can
be read by the person. In a case where the sensors are to be mounted on the
carrier by a machine, the indicia may be machine-readable indicia which
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cannot be read directly by a person. The machine or person would position
the sensors on successive carriers in accordance with a predetermined
programme.
The carriers 122 are provided with respective resiliently flexible teeth
123 for holding the carriers together. One of the carriers is formed with a
peripheral groove in which there is engaged a clip 124, parts of which are also
seated in a groove formed in an inwardly facing surface of the body 110, so
that moYement of the c~rriers along the axis 11 2 relative to the body is
restrained. The teeth 123 of the carrier remote from the operating member
113 engage a cover 125 which covers the sensors of that carrier to prevent
escape oF the sensors from the carrier.
The sensors 121 are connected electrically with a programmable logic
device 126 proarammed according to the positions of the magnetic poles of
the key, to recognise a particular key. Alternatively, the logic device may be
adapted to enter into a memory information which identifies each key
inserted into the opening 114.
The device shown in Figure 8 may be used to control a bolt (not shown).
For this purpose, there may be on one of the carriers a driving element 127,
shown in Figure 9, engageable with a movable pin 128, through which drive
can be transmitted to the bolt. Movement of the bolt may be further
controlled by the logic circuit associated with the sensors 121. For example,
there may be associated with the bo1t a detent which normally prevents
movement of the bolt but which will release the bolt when the logic circuit
receives signals from appropriate ones of the sensors 121. With this
arrangement, the bolt can be moved only when both the sensors 121 and the
locking elements 117, 118 and 119 have responded in a predetermined manner
to the magnetic field of the key.
The device preferably includes a solenoid having an armature connected
with the detent and so associated with the logic circuit that the ~olenoid is
mqintained in un electrically energised condition whilst the appropriate key
remains in the opening 11~.
It is intended that the key 11 should have not more than two magnetic
poles arranged to influence sensors on the same carrier. \Nhilst three sensors
may be mounted on each carrier, only two of these would be used when the
device is operated by a particular key. The logic circuit is preferably
arranged to prevent energisation of the solenoid if an additional Hall effect
device is subjected to a magnetic field or one of the Hall effect devices is
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subjected to the influence of an adjacent magnetic pole of incorrect polarity.
The device may also be arranged to provide an audible or visual alarm in such
circumstances. The device is preferably arranged for use with a key having
distinct poles of one polarity only, so that insertion of a key with an oppositepole will cause the alarm to be provided.
It will be noted that the sensors 121 are operated by the magnetic field
of the key alone. No supplementary sources of magnetic flux are provided in
the device to supplement or modify the magnetic action of the key.
In a case where the key has been magnetised by means of a magnetising
head, as shown in Figure 5, the sensors 121 occupy positions such that, when
the key 11 has been fully inserted, each sensor is offset slightly from the
centre of a magnetic pole of the key and is aligned with the annular region of
high flux density in the magnetic pole. The arrangement may be such that,
during insertion of the key, one part of the area of high flux density of the
magnetic pole passes the sensor and an opposite part of the area of high flux
density comes to rest in alignment with the sensor. With this arrangement,
the sensor would provide two signals during insertion of the key. If sensors of
sufficiently compact form are used, two sensors may be positioned to respond
to a single magnetic pole, opposite parts of the region of high flux density of
the pole being aligned with respective ones of the sensors when the key has
been fully inserted. The logic circuit would then be arranged to permit
energisation of the solenoid only if both of the sensors intended to be aligned
with a single magnetic pole of the key provide an output signal.
The apparatus shown in Figure I, optionally modified by adoption of the
magnetising head shown in Figure 5, may be used to provide a plurality of
magnetic poles on a body which is used in conjunction with a magnetic sensor
or a plurality of sensors to respond to rotation of the body relative to the
sensor by providing an electrical output signal at a frequency dependent on
the speed of rotation. The sensor can be arranged to provide two pulses or
signal elements in response to movement of a single magnetic pole past the
sensor, the sensor responding to a first part of the region of high magnetic
flux density and then to a second part of the region of high magnetic flux
density.
