GB2391315A

GB2391315A - Detection apparatus and detectable component

Info

Publication number: GB2391315A
Application number: GB0217387A
Authority: GB
Inventors: David Bernard Mapleston; Andrew David White
Original assignee: Innovision Research and Technology PLC
Current assignee: Broadcom Innovision Ltd
Priority date: 2002-07-26
Filing date: 2002-07-26
Publication date: 2004-02-04
Also published as: GB0217387D0

Abstract

A detection system comprises a detection apparatus (2) for detecting relative movement of a magnetic element detectable component (3). The apparatus comprises an oscillator coupled to a detection component which has an impedance that varies with magnetic field when an oscillating signal is applied to it. The detection component may exhibit giant magneto impedance (GMI). A sensor detects impedance variations of the detection component resulting from movement of the magnetic element (3) relative to the detection apparatus (2) and an output indicates such impedance changes. The detection system may be used in a toy or game, in a flowmeter, level indicator, or for tagging applications where relative movement is to be sensed.

Description

DETECTION APPARATUS AND

COMPONENT DETECTABLE BY THE DETECTION APPARATUS

This invention relates to detection apparatus and a 5 component detectable by the detection apparatus. In particular, but not exclusively, the present invention relates to toys or games comprising such a detection apparatus and detectable component wherein an operation or response of the toy or game is affected by detection 10 of a detectable component.

In many toys and games providing the facility to sense the proximity of an item or character brings magic to the toy or game for the child. For example, a toy dog may 15 respond with sound or action when a toy bone is held close by or waved at a certain rate. Current techniques for sensing the proximity of an item or character rely on Hall effects semiconductor devices, radio frequency (RF) passive tags, induction coils or in some cases 20 simple Reed switches. The range and reliability of such devices may however, be relatively limited.

The ability to conduct remote sensing or detection at greater range and with greater reliability is also 25 desirable in areas outside the fields of toys and games,

for example in the areas of flow and pressure sensing.

In one aspect, the present invention provides a detection system comprising a detection apparatus and a detectable 30 component detectable by the detection apparatus, the

( detectable component comprising a magnetic element movable relative to the detection apparatus and the detection apparatus comprising a detection component having an impedance that varies with magnetic field when

5 an oscillating signal is supplied to the detection component, the detection apparatus further comprising means for applying an oscillating signal to the detection component, means for sensing variation in the impedance of the detection component and means for providing an 10 output signal dependent upon any sensed variation in the impedance of the detection component and thus movement of the magnetic element.

In an embodiment, the detection component comprises a 15 substantially amorphous material which exhibits giant magneto-impedance (GMI) as described in a paper by L V Panina and K Mohri published in the Journal of the Magnetic Society of Japan, volume 19, pages 265 to 268 in 1995 and entitled "High Frequency Giant 20 Magneto-impedance in Cobalt Rich Amorphous Wires and Films". Examples of materials that exhibit the GMI effect are, for example, amorphous cobalt alloys such as CoFeSiB and 25 nickel-iron plated beryllium copper wire. Any other material that exhibits giant magneto-impedance properties or any combination of materials exhibiting giant magneto-impedance may be used.

( In one embodiment, the detection apparatus and detectable component are housed in the same body with the detectable component being housed to enable movement of the magnetic element relative to the detection apparatus.

In another embodiment, the detection apparatus and detectable component are housed in separate bodies that may be removed relative to one another.

10 In one embodiment, the detectable component comprises a movement constraining member that constrains movement of the magnetic element. In one embodiment, the movement constraining member comprises a spring such as a coil or leaf spring coupling the magnetic element to a support 15 of the detectable component. In another example, the coupling member comprises a simple or compound pendulum coupling the magnetic element to a support of the detectable component.

20 In another embodiment, the constraining member defines a path along which the magnetic element may move, For example, the constraining member may be a U-tube within which the magnetic element may move. As another possibility the magnetic element may be mounted on a fly 25 wheel or other rotatable member such as an eccentrically mounted cam.

In an embodiment, the magnetic element is movable by a user manually moving the detectable component where the 30 detectable component and detection apparatus are separate

( and/or by manually moving the detection system where the detectable component and detection apparatus are provided within the same housing or body.

5 In another embodiment, the detection apparatus comprises means for exciting movement of the magnetic element, for example a coil and a coil driver for generating an electromagnetic pulse or pulses to repel or retract the magnet. In such a case, manual movement of the 10 detectable component is not necessary.

In another embodiment, the detectable component may be mounted on a member that is movable by fluid flow (where the fluid may be a gas or a liquid), for example, the 15 detectable components may be mounted on a paddle wheel rotatable by movement of a fluid along a pipe.

In an embodiment, a number of different detectable components are provided each having magnetic elements 20 with different motion characteristics. In an embodiment, the different motion characteristics are provided by coupling members having different characteristics, for example by springs having different spring constants or masses giving different vibration frequencies.

In an embodiment, two or more detectable components are provided to provide a position or balance sensor.

! In an embodiment, the detection system is incorporated within a toy such as a soft toy, for example a teddy bear. 5 In an embodiment, the detection apparatus is incorporated in a toy such as a soft toy and the detectable component is incorporated in an item usable with the soft toy. For example, the detection apparatus may be incorporated in a toy dog and the detectable component in a toy bone or 10 toy baby animal or vice versa.

In an embodiment, a number of different detectable components are provided each having different detection characteristics. For example, a family of toy animals may 15 be provided with each different toy animal having different detection characteristics.

In an embodiment, the detectable component is designed to be inserted into a pipe or tube along which fluid 20 flows. In an embodiment, the detectable component is designed to be attached to a paddle wheel or similar rotatable member mounted within a pipe or tube to detect fluid flow.

25 Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a very diagrammatic view of a toy embodying the invention showing in phantom lines 30 incorporation of a detection system within the toy;

Figure 2 shows a functional block diagram of one example of a detection apparatus of a detection system embodying the invention; Figure 2a shows a detailed circuit diagram of one 5way in which part of the detection apparatus shown in Figure 2 may be implemented; Figures 3 to 7 show various diagrammatic sectional views of different detectable components embodying the present invention; 10Figure 8 shows a functional block diagram of another example of detection apparatus embodying the present invention; Figure 9 shows a very diagrammatic representation of another example of a toy embodying the present 15invention; Figure 10 shows a very diagrammatic representation of another example of a toy embodying the present invention; Figure 11 shows a very diagrammatic representation 20of another example of a toy embodying the present invention; Figure 12 shows a very diagrammatic representation of part of an example of a game embodying the present invention; 25Figure 13 shows a very diagrammatic drawing for illustrating a pedometer embodying the present invention; Figure 14 shows a very diagrammatic representation of another example of a game embodying the present invention; and

! Figure 15 shows an example of use of a detection system embodying the present invention to detect fluid flow. 5 A first example of a toy embodying the invention and incorporating a detection system embodying the invention will now be described with reference to Figures l, 2, 2a and 3 in which Figure 1 shows a very diagrammatic representation of the toy 1, in this case a teddy bear, 10 Figure 2 shows a functional block diagram of detection apparatus of the detection system, Figure 2a shows a circuit diagram of one implementation of part of the detection apparatus shown in Figure 2, and Figure 3 shows a very diagrammatic representation of a detectable 15 component 3 with a housing 3a of the detectable component shown cut away to enable a moveable magnetic element 4 of the detectable component 3 to be seen. The detection apparatus 2 is provided within its own housing 2a as illustrated very diagrammatically in Figure 2 and, as 20 shown in phantom lines in Figure 1, the detection apparatus 2 and detectable component 3 are both provided within a sealed unit 5 incorporated within the teddy bear 1.

25 As shown in Figure 2, in this example the detection apparatus 2 comprises an oscillator 10 which is coupled to a power supply line 100 via a power decoupled 30 and which is arranged to generate a low frequency, typically about 90 kHz, square wave signal. In the interests of

simplicity, the power supply, generally a battery, and connections to the power supply are omitted in Figure 2.

The oscillator 10 is coupled via a resistor Rll to one 5 end of a component receiver such as a J2 header which is coupled to ground G and into which is fitted a detection component 20 that has an impedance that varies with magnetic field when the low frequency signal from the

oscillator is supplied through the detection 10 component 20.

The detection component comprises one or more materials that exhibit giant magneto-impedance as described in the aforementioned paper by L V Panina and K Mohri.

15 Typically, the detectable component comprises an amorphous cobalt alloy such as CoFeSiB (for example (COT_ XFex)2sSi5Bl5 or nickel-iron beryllium-copper wire.

Other materials or combinations of materials exhibiting the GMI effect may be used.

Typically, the resistor R11 may have nominal resistance of 100 ohms while the detection component comprises 5 cm of GMI material having a nominal resistance of 10 ohms.

The junction J1 between the resistor all and the 25 detection component 20 is coupled to an active low pass filter 21. The output of the active low pass filter 21 is coupled to a signal amplifier 22. The output of the amplifier 22 is supplied to an AC input stage that incorporates oC biassing to move the signal back to mid 30 rail. The AC input stage 23 couples the AC signal to an

active filter 24 that attenuates interference and noise, The output of the active filter 24 is supplied to a high gain AC amplifier 2S which provides an input to a simple 5 RC low pass filter 26 which outputs an effectively digital signal having a frequency corresponding to the frequency of oscillation of the magnetic field to which

the detection element 20 is subjected. The output of the RC filter 26 provides one input to a comparator 27. The 10 other input to the comparator 27 is a threshold voltage VT. The output of the comparator 27 is supplied, in this example, to a microprocessor 31 for further processing.

The output of the comparator 27 may optionally also be 15 supplied to an LED (Light Emitting Device) driver 28 coupled to drive an LED L1, for example a green LED, that flashes in operation of the detection apparatus when a magnetic field is detected by the detection component.

In the case of the toy shown in Figure 1, the LED L1 may 20 be incorporated into a.facial feature of the toy such as an eye or nose.

The microprocessor 31 is associated with or incorporates a memory 32 storing program instructions for controlling 25 operation of the microprocessor 31 to analyse and respond to the signals supplied as a result of detection of a detectable component by the detection component 20. The microprocessor 31 is coupled to an output device 34 that may comprise a loudspeaker 35 and a display 36 which may,

for example, be in the form of one or more light emitting devices such as light emitting diodes.

The threshold voltage VT of the comparator 27 is set so 5 that output signals are supplied by the comparator 27 to the microprocessor 31 when a detectable component 20 is moved relative to the detection apparatus within a range of a few feet from the detection apparatus.

10 For the sake of completeness, Figure 2a shows a circuit diagram illustrating one way in which the functional components of the detection apparatus within block 40 in Figure 2 may be implemented.

15 In this embodiment, as shown very diagrammatically in Figure 3, the detectable component 3 comprises a magnetic element 4 in the form of a small permanent magnet mounted to a support 5 via a coil spring 6.

20 Assuming that the battery (not shown) is coupled to the detection apparatus by operation of a switch (Figure 1), then, in this embodiment, when a child picks up or moves the teddy bear 1, this will cause the magnetic element 4 to move with the manner of movement being determined 25 by the motion characteristics defined by the weight of the magnetic element 4 and the spring constant of the coil spring 6.

Movement of the magnetic element 4 will cause a variation 30 in the magnetic field to which the detection component

( 11 1 20 is subjected thereby causing a change in the impedance of the detection component, resulting in signals being supplied to the microprocessor 31 indicating movement of the toy 1. In response, the microprocessor 31 provides 5 an output to the child via the output device 36. For example, the microprocessor may retrieve audio data from the memory 32 to cause the loudspeaker 35 to play a tune or speak a message to the child. Alternatively or additionally, the microprocessor 31 may cause the display 10 36 to flash one or more lights.

The microprocessor 31 may be arranged simply to detect any movement of the magnetic element. The microprocessor 31 may be arranged simply to receive the digital output 15 of the comparator 27 so that the microprocessor 31 causes an output to be supplied to the child when the threshold VT is exceeded. As another possibility where the microprocessor 31 includes analogue-to-digital conversion circuitry 31 (or a separate analogue-to-digital 20 conversion circuit is provided), then the microprocessor 31 may receive an analogue signal from the low pass filter 26 and may determine from the variation in the magnetic field, the degree and/or duration of motion of

the magnetic element. For example, the microprocessor 25 31 may be arranged to determine whether the child is simply carrying the toy or is shaking the toy gently or vigorously. In such a case the microprocessor 31 may be arranged to select different output data from its memory 32 in accordance the degree and/or manner of motion of 30 the magnetic element.

The above described detection apparatus is relatively sophisticated and enables detection of different degrees and types of movement of the toy 1. As another possibility, a relatively simple detection apparatus can 5 be provided that just detects whether or not there is movement of the magnetic element and thus of the toy 1.

In this case, the detection apparatus may consist simply of the components shown in the box 40 in Figure 2 so that the LED L1 flashes when a varying magnetic field is

10 detected by the detection component 20. The LED L1 and its driver may be replaced or supplemented by a loudspeaker and driver so that a sound is emitted when a varying magnetic field is detected by the detection

component 20. As another possibility, the detection 15 apparatus may consist simply of the oscillator 10, power supply decoupler 30, resistor R11, GMI component 20, active filter 21 and amplifier 22 and the amplifier 22 may be coupled to drive an output device in the form of a loudspeaker that emits a sound and/or a light emitting 20 device (for example, in a facial feature such as a nose of the toy) that lights up when the detection component 20 detects a variation in the magnetic field due to

motion of the magnetic element 4 resulting from, for example, a child moving the toy.

In the above described embodiment, the detectable component 3 comprises a magnetic element 4 coupled via a coil spring 6 to a support 5. Figures 4 to 7 show other examples of detectable component 3. In the example 30 shown in Figure 4, the coil spring 6 is replaced by a

( leaf spring 6a. Other forms of spring or resilient material may be used to form the coupling element coupling the magnetic elements 4 to the support 5 to enable motion of the magnetic element 4 relative to the 5 support S. In each case, the characteristics of the motion being determined by the coupling element and the weight of the magnetic element.

As another possibility, the detectable component 4 may 10 comprise a pendulum with the magnetic element 4 forming a weight of the pendulum. Figures 5 and 6 show two different examples of pendulum type arrangements. The arrangement shown in Figure 5 comprises a simple pendulum in which the magnetic element 4 is mounted to a free end 15 of a support rod 40 pivotally mounted at its other end to a post 41 carried by the support member S so that when the detectable component 3 is moved, the support rod 40 executes simple harmonic motion with a period determined by the length of the rod 40 as the characteristic motion.

20 The arrangement shown in Figure 6 comprises a compound pendulum in which the magnetic element 4 is mounted to a free end of a further support rod 42 itself pivotally coupled to the support rod 40. In this case, the characteristic motion is determined by the lengths of the 25 elements of the compound pendulum.

Other forms of mechanisms for constraining or controlling movement of the magnetic element 4 may be used. For example, the magnetic element 4 may be constrained within 30 a housing or cage defining a particular path and thus a

characteristic motion for the magnetic element. For example, this housing or cage may, as shown in Figure 7, constitute a U-tube 45 mounted on the support 5 with again the characteristic motion being simple harmonic 5 motion having defined period.

In each of the examples shown in Figures 3 to 7, motion of the detectable component 3 causes movement of the magnetic element 4 in a manner defined by the 10 constraining member which may be a coupling member such as the spring or pendulum rod or support or may be a housing defining a path for motion of the magnetic element. 15 In the above described examples, motion of the magnetic element 4 is caused by the child picking up or shaking the toy 1. Figure 8 shows another example of detection apparatus embodying the present invention in which, in addition to the detection circuitry described above with 20 reference to Figure 2, the detection apparatus comprises an excitation coil 50 and a coil driver 51 that, under control of the microprocessor 31, generates a current pulse that causes the coil SO to generate a magnetic pulse which attracts or repels the magnetic element to 25 initiate motion of the magnetic element. In this case, the microprocessor 31 will be arranged to detect motion of the magnetic element after the magnetic pulse has subsided.

As modification of this arrangement, and to facilitate excitation of motion of the magnetic element 4, the coil driver 51 may be arranged to drive the excitation coil 50 with an AC current of the same frequency as the 5 natural oscillation frequency of the magnetic element.

In the above described examples, the detectable component 3 is incorporated in the same body as the detection apparatus 2. This need not be the case and, for example, lo the detectable component 3 may be incorporated in a separate item or character. To illustrate this, Figure 9 shows an example of a child's soft toy in the form of a toy dog 60 and a toy bone 61 one of which incorporates the detection apparatus and the other the detectable 15 component. In the example shown in Figure 9, the detectable component 3 is incorporated in the toy bone 61 and the detection apparatus 2 is incorporated within the toy dog.

20 In this case the detection apparatus may be arranged simply to detect movement of the toy bone 61 into the range of the detection apparatus so that, when the child brings the toy bone 61 close to the toy dog 60, the microprocessor 31 causes the loudspeaker 35 of the output 25 device to emit a sound such as a barking noise. As another possibility or additionally, the microprocessor 31 may be arranged to detect continuous motion of the toy bone 61 so that, when the child waves the toy bone 61 under the nose of the toy dog 60, the loudspeaker 35 30 emits a barking noise or a different barking noise.

In the above described examples, a single detectable component 4 is provided that is incorporated within the toy or within a component usable with the toy.

5 In the example shown in Figure 9, a number of different components may be provided that a child can play with.

For example, in addition to the toy bone 61 a toy ball or like item can be provided that also incorporates a detectable component. In this case, the detectable 10 components will have different motion characteristics so that the different detectable components 4 provide characteristic different signals that the microprocessor 31 can distinguish. For example, where the coupling member is a spring as shown in Figure 3 or 4, then the 15 different detectable components 4 may be arranged to have different resonant frequencies (by changing the spring constants and/or the weight or mass of the coupling member and/or the magnetic element) enabling the microprocessor to distinguish different detectable 20 components on the basis of the frequency of the detected signal. Where the coupling member is a pendulum as shown in Figure 5 or 6, then the different detectable components 4 may have different oscillation periods by changing the pendulum length enabling the microprocessor 25 to distinguish different detectable components on the basis of the period of oscillation. In this case, the memory 32 may store different output data associated with different resonant frequencies so that the microprocessor 31 supplies different output data to the output device 30 34 dependent upon the detected resonant frequency.

Such a detection apparatus may be used to enable a number of different soft toys to be recognized by a further soft toy. For example, a soft toy representing an adult animal such as a rabbit 70 as shown in Figure 10 may 5 incorporate the detection apparatus 2 and a number of different soft toys representing baby animals, in this case baby rabbits 71, may each incorporate a detectable component 3 with the different detectable components having different motion characteristics so that the 10 microprocessor 31 of the detection apparatus 2 within the toy 70 can distinguish the different toys 71 and cause the output device 34 to supply output data dependent upon which one of the toy 71 is detected. For example, microprocessor 31 may cause the loudspeaker to emit 15 sounds so that the toy 70 speaks the name of the detected toy 71 so that it appears to the child as if the parent toy 70 has recognised one of its children.

Where the detection apparatus incorporates the excitation 20 coil as shown in Figure 8, then a separate switch SW2 may be provided on the exterior of the toy 70 so that the child can cause the microprocessor 31 to activate the coil driver 51 to excite motion of the magnetic element within the toy 71 closest to the toy 70. Where a number 25 of different toys 71 are provided with different resonant frequency detectable components 4, then the microprocessor 31 may be arranged to cause the excitation coil 52 to be driven at each resonant frequency in turn with a rest period between to enable detection by the 30 microprocessor 31 of any response at that frequency. The

microprocessor 31 may determine the frequency of any received AC signal by, for example, counting the number of pulses received within a predetermined time in known manner. In the above described examples, an excitation coil 52 may be used to excite motion of the or a magnetic element. As another possibility, the excitation coil may be replaced by a permanent magnet which is rotated or lo oscillated at the resonant frequency of the detectable component or components.

Such a moveable magnet or magnetic element may be replaced by a fixed magnet and a movable or rotatable 15 mumetal disk. In addition, the moveable magnetic element 4 itself need not necessarily comprise a permanent magnet but could comprise a movable mumetal component such as a disk associated with a fixed permanent magnet.

20 The detection apparatus described above can measure not only variation but also the strength of the magnetic field. This may enable the location of the detectable

component 3 to be determined in two or three dimensions if two or three detection apparatus are provided. For 25 long range detection, then the detectable component itself may be powered to cause vibration of the magnetic element 4. Where the detectable component is powered, then the magnetic element may comprise a coil of wire through which a DC or AC current is caused to flow.

A detection system embodying the present invention may also be used to provide a low cost balance feedback sensor for example for use a robot toy 80 as shown in Figure 11. In this case, two detection apparatus 2 are 5 provided and the magnetic element 4 is suspended from a support 5 so that, as the robot toy 80 moves, the magnetic 4 swings back and forth. In this case, another microprocessor within the robot toy may be configured to control drive motors within the robot toy to maintain 10 signals output by the microprocessors 27 of the detection apparatus at the same level or strength, thereby maintaining the magnetic element 4 at a central position.

The housing of the detectable component 3 may contain a 15 fluid for damping motion of the magnetic element 4.

There are many other applications for detection systems embodying the present invention. For example, such detection systems may be used in toy vehicle sets where, 20 as illustrated very diagrammatically in Figure 12, a toy vehicle 90 contains a detectable component 4 and a vehicle track or mat 91 carries or is associated with the detection apparatus 2 so that, as the toy vehicle moves over or past the detection apparatus, the changing 25 magnetic field causes a change in the impedance of the

GMI detection component 20, enabling the detection apparatus 2 to detect the presence of the toy vehicle 90.

The detection apparatus may use this information to record the time of passage of the vehicle over a 30 particular point, for example to record lap times of the

( vehicle around a track, or may emit a sound or cause lights to flash when the vehicle passes by or over the detection apparatus.

5 The magnetic element may comprise an arrangement of small magnets 4a as shown in Figure 12 with the space in between the small magnets 4a being different for different toy vehicles so enabling the detection apparatus 2 to identify different toy vehicles 90.

In the example described with reference to Figure 12, movement of the detectable component is achieved by motion of the toy vehicle. The toy vehicle may, however, contain a detectable component such as one of those shown 15 in Figures 3 to 7 where the magnetic element 4 is coupled to a support via a coupling member and the detection apparatus 2 may be arranged as described above with reference to Figure 8 to excite movement of the magnetic element. In this case, different toy vehicles may have 20 different resonant frequency or motion characteristics so enabling the detection apparatus to detect different toy vehicles.

As another possibility, the detection apparatus 2 may be 25 placed in the toy vehicle and the small magnets 4a incorporated within the track or play mat. In this case, the detection apparatus 2 may be arranged to emit a sound or cause lights to flash within the toy vehicle when the toy vehiclepasses over or close to the magnetic element 30 4.

( A detection system embodying the invention may also be used to provide a pedometer as illustrated very diagrammatically by Figure 13 by incorporating a magnetic element 4 in the form of a permanent magnet in one shoe 5 and the detection apparatus 2 in the other shoe enabling the microprocessor 31 to determine from the changing magnetic field as the wearer walks, the speed and stride

of the wearer, which should enable the distance travailed to be determined by the microprocessor 31.

A detection system embodying the present invention may also be used in a spinning top game by, as shown diagrammatically in Figure 14, incorporating a magnetic element 4 in the form of a permanent magnet on a spinning 15 top 94 and providing the detection apparatus 2 so that it can be positioned adjacent the top when it is spun so that the microprocessor 31 can determine from the changing magnetic field the spin speed and duration of

spin of the top. It may also be possible for the 20 detection apparatus to determine the distance of the spinning top from the reader 95 from the magnitude or strength of the detected signal. A similar reader may also be used to determine speed of rotation or bouncing of a ball incorporating a magnetic element. Similar 25 principles may be used to create electronic dice.

The above described examples comprise toys or games. A detection system embodying the invention may also have other applications. For example, because, as described 30 above, different detectable components 3 can be

( manufactured with unique or different motion characteristics, such detectable components may be used to identify or tag items and would be readable by a detection apparatus over a relatively large range of a 5 few feet. Accordingly, such detectable components may provide a relatively cheap form of passive tagging or ID device. A detection system embodying the present invention may lo also be used to produce a flow meter. An example of a flow meter embodying the present invention is illustrated very diagrammatically by Figure 15 which shows a portion of a pipe 110 through which a fluid (which may be gas or liquid) is flowing. Within the pipe llO is mounted a 15 rotatable wheel Ill on one arm of which is fixed a magnetic element 4 in the form of a permanent magnet.

The detection apparatus 2 is positioned outside the pipe or tube llO adjacent the wheel 111. The rotational speed of the wheel 111 and thus of the magnetic element 4 will 20 be proportional to the rate of flow of the fluid and can be determined by the detection apparatus 2 from the change in the magnetic field resulting from rotation of

the wheel 111. Such a flow meter should enable relatively low flow rates to be measured and should be 25 cheaper than existing Hall effect type flow meters. An extra benefit is that the sensor can be remote from the reader. This gives the ability to easily change the flow meter or sensor if it becomes damaged, and allows for it to be mounted in a hygienic carrier which can be easily 30 detached and replaced.

Where the detectable component comprises a magnetic element mounted on a resilient member such as a spring, then such a detectable component may be tracked when travailing along a pipe or path by exciting motion of the 5 magnetic element as described above. Such a detectable component may be used possibly, for example, as a gastric tracing pill.

Detection apparatus embodying the present invention may 10 also be used to measure the flow of fluids that contain a small proportion of iron and that may therefore be magnetised. For example, it may be possible to use detection apparatus embodying the present invention to sense blood flow by briefly magnetising the blood by 15 placing a coil of wire or a rotating magnet on the surface of the skin and positioning the detection apparatus a short distance downstream from the magnetizing device.

20 The detectable components described above may be arranged so as to float on or within a body of fluid so that a detection system embodying the present invention may be used as a level or depth gauge.

25 Detection of vibration of part of a machine or the like may also be detected by mounting a magnetic element 4 to the part of the machine susceptible to vibration and positioning the detection apparatus a short distance away. Such a system may also be used to detect sound

( vibration and may be used as the basis of a throat microphone, for example.

Claims

2s CLAIMS:

1. A detection system comprising a detection apparatus and a detectable component detectable by the detection 5 apparatus, the detectable component comprising a magnetic element movable relative to the detection apparatus and the detection apparatus comprising: an oscillator for providing an oscillating signal; a detection component coupled to receive the 10 oscillating signal,, the detection component having an impedance that varies with magnetic field when the

oscillating signal is supplied to the detection component; sensing means for sensing variation in the impedance 15 of the detection component; and output means for providing an output in accordance with variation of the impedance sensed by the sensing means and resulting from movement of the magnetic element relative to the detection apparatus.

2. A detection system according to claim 1, wherein the detectable component comprises a housing within which the magnetic member is movable.

25 3. A detection system according to claim 2, wherein the housing constrains moment of the magnetic element to movement along a predefined path.

4. A detection system according to claim 1, wherein the 30 detectable component further comprises a support and a

coupling member, the coupling member coupling the magnetic element to the support to allow movement of the magnetic element relative to the support.

5 5. A detection system according to claim 4, wherein the coupling member comprises a resilient member.

6. A detection system according to claim 4, wherein the coupling member comprises a spring.

7. A detection system according to claim 4, wherein the coupling member and magnetic element define a pendulum.

8. A detection system according to any of claims 2 to 15 7, wherein the magnetic element has a predefined motion characteristic. 9. A detection system according to claim 8, wherein the predefined motion characteristic is a frequency at which 20 the magnetic element is arranged to execute periodic motion. 10. A detection system according to claim 8 or 9, wherein a number of detectable components are provided 25 each having a different predefined motion characteristic and the detection apparatus is arranged to distinguish different motion characteristics

11. A detection system according to any of the preceding claims, wherein the or each detectable component is separate from the detection apparatus.

5 12. A detection system according to any of claims 1 to 9, wherein the or each detectable component and the detection apparatus are housed within a common body.

13. A toy comprising a detection system in accordance 10 with any of the preceding claims.

14. A game comprising a detection system in accordance with any of the preceding claims.

IS 15. A toy comprising a detection system in accordance with any of claims 1 to 9, wherein one of the detection apparatus and detection component is housed within the body of the toy and the other is housed within an item usable with the toy so that when a user moves the item 20 relative to the toy an output representative of that movement is provided.

16. A toy comprising a detection system in accordance with claim 10, wherein the detection apparatus is housed 25 within the body of the toy and a number of items usable with the toy are provided each carrying a detectable component with each item having a different motion characteristic, the detection apparatus being arranged to cause the toy provide an output dependent on the 30 distinguished motion characteristic.

( 17. A game comprising a detection system in accordance with claim 10, wherein each detectable component comprises or forms part of an item or component of the game. 18, A game according to claim 17, wherein the detectable components are carried by toy vehicles.

19. A flow meter comprising a detection system according 10 to any of claims 1 to 11, wherein the or each detectable component is arranged to move in response to motion of fluid along a flow path.

20. A flow meter according to claim 19, wherein the or 15 each detectable element is attached to a rotatable support arranged to be supported within the flow path so as to be rotated by fluid flow.

21. A position sensor comprising a detection system in 20 accordance with any of claims 1 to 11, wherein the sensing means is arranged to detect the strength of the varying magnetic field produced by movement of the

magnetic element and position determining means are provided for determining position on the basis of 25 detected magnetic field strength.

22. A balance correction device comprising a detection system in accordance with any one of claims 1 to 11, having at least one further detection apparatus and 30 balance adjusting means for adjusting balance in

( accordance with the relative outputs of the at least two detection apparatus.

23. A detection apparatus for detecting a detectable 5 component comprising a magnetic element movable relative to the detection apparatus, the detection apparatus - comprising: -

an oscillator for providing an oscillating signal; a detection component coupled to receive the oscillating 10 signal, the detection component having an impedance that varies with magnetic field when the oscillating signal

is supplied to the detection component; sensing means for sensing variation in the impedance of the detection component; and 15 output means for providing an output in accordance with variation of the impedance sensed by the sensing means and resulting from movement of the magnetic element relative to the detection apparatus.

20 24. A detection apparatus according to claim 23, arranged to distinguish different motion characteristics of different detectable components.

25. A toy comprising a detection apparatus in accordance 25 with claim 23 or 24.

26. A game comprising a detection apparatus in accordance with claim 23 or 24.

( 27. A toy comprising a detection apparatus in accordance with claim 23 or 24, wherein one of the detection apparatus and detection component is housed within the body of the toy and the other is housed within an item 5 usable with the toy so that when a user moves the item relative to the toy an output representative of that movement is provided.

28. A toy comprising a detection apparatus in accordance 10 with claim 23 or 24, wherein the detection apparatus is housed within the body of the toy wherein a number of items are usable with the toy each carrying a detectable component with each item having a different motion characteristic, the detection apparatus being arranged 15 to cause the toy provide an output dependent on the distinguished motion characteristic.

29. A detectable component for use with detection apparatus in accordance with claim 24, the detectable 20 component comprising a housing and a magnetic element movable relative to the detection apparatus within the housing. 30. A detection component according to claim 29, wherein 25 the housing constrains moment of the magnetic element to movement along a predefined path.

31. A detection component according to claim 29, wherein the detectable component housing also contains a support 30 mounted to the housing and a coupling member coupling the

( magnetic element to the support to allow movement of the magnetic element relative to the support.

32. A detection component according to claim 31, wherein 5 the coupling member comprises a resilient member.

33. A detection component according to claim 31, wherein the coupling member comprises a spring.

10 34. A detection component according to claim 31, wherein the coupling member and magnetic element define a pendulum. 35. A detection component according to any of claims 29 15 to 34, wherein the magnetic element has a predefined motion characteristic.

36. A detection component according to claim 35, wherein the predefined motion characteristic is a frequency at 20 which the magnetic element is arranged to execute periodic motion.

37. An assembly of detectable components for use with detection apparatus in accordance with claim 24 each 25 detectable component having a different predefined motion characteristic 38. A toy comprising a detectable component or components in accordance with any of claims 29 to 37.

39. A game comprising a detectable component or components in accordance with any of claims 29 to 37.

40. A toy vehicle carrying a detectable component or 5 components in accordance with any of claims 29 to 37.

41. A vibration detector comprising a detection system in accordance with any of claims 1 to 9, wherein the detectable component is arranged to be mounted to a part 10 that vibrates in operation.