WO2004102370A2 - Appareil de detection - Google Patents

Appareil de detection Download PDF

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Publication number
WO2004102370A2
WO2004102370A2 PCT/GB2004/002094 GB2004002094W WO2004102370A2 WO 2004102370 A2 WO2004102370 A2 WO 2004102370A2 GB 2004002094 W GB2004002094 W GB 2004002094W WO 2004102370 A2 WO2004102370 A2 WO 2004102370A2
Authority
WO
WIPO (PCT)
Prior art keywords
sensor
winding
excitation winding
magnetic field
signal
Prior art date
Application number
PCT/GB2004/002094
Other languages
English (en)
Other versions
WO2004102370A3 (fr
Inventor
Mark Anthony Howard
David Alun James
Richard Alan Doyle
Colin Stuart Sills
Ross Peter Jones
Darran Kreit
Bruce Macaulay
Vicki Clark
Alan Hay
Ingrid Brown
Original Assignee
Sensopad Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB0311098A external-priority patent/GB0311098D0/en
Priority claimed from GB0322585A external-priority patent/GB0322585D0/en
Priority claimed from US10/724,336 external-priority patent/US7196604B2/en
Application filed by Sensopad Limited filed Critical Sensopad Limited
Publication of WO2004102370A2 publication Critical patent/WO2004102370A2/fr
Publication of WO2004102370A3 publication Critical patent/WO2004102370A3/fr

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/02—Input arrangements using manually operated switches, e.g. using keyboards or dials
    • G06F3/0202—Constructional details or processes of manufacture of the input device
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
    • G06F3/0338—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2221/00—Actuators
    • H01H2221/008—Actuators other then push button
    • H01H2221/012—Joy stick type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2239/00—Miscellaneous
    • H01H2239/024—Miscellaneous with inductive switch
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/965—Switches controlled by moving an element forming part of the switch
    • H03K17/97—Switches controlled by moving an element forming part of the switch using a magnetic movable element
    • H03K17/972—Switches controlled by moving an element forming part of the switch using a magnetic movable element having a plurality of control members, e.g. keyboard
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/965—Switches controlled by moving an element forming part of the switch
    • H03K17/97—Switches controlled by moving an element forming part of the switch using a magnetic movable element
    • H03K2017/9706—Inductive element

Definitions

  • This invention relates to interfaces for use in measuring applied forces.
  • interfaces which can measure magnitude, or direction or location of such forces .
  • capacitive touch sensors are already known in which the change in properties of electrically charged plates or conductors changes due to the proximity of a user's finger or other implement.
  • Such sensors can be in the form of singlepoint proximity type devices or can extend in one or two axes. They are commonly used for cursor controls in portable computers.
  • Such capacitive devices suffer from their inability to differentiate between a user' s finger and water or other extraneous matter. Consequently, capacitive devices are not well suited to harsh environments where the capacitive plates may become wet or covered in foreign matter.
  • Infrared proximity sensors are also known in which the disturbance of an infrared beam caused by a user's finger is used as a method of data entry.
  • Such devices are constrained by the need to be contained behind a housing material that is transparent to infrared transmissions, for example glass.
  • this generally precludes the use of infrared devices from harsh environments where infrared measurement techniques may suffer interference from extraneous matter such as dirt, grease etc.
  • This invention is concerned with the provision of low cost yet robust input devices for electronic systems in which small deflections of a member such as, bar or plate caused by either by manual interaction by a user or by some externally applied pressure is measured inductively.
  • Such devices employ more than one sensor and can find application in many fields such as tilt sensors (e.g. in vehicles), pressure sensor, rotary sensor, man-machine interface (telephone/cash machine keypad or touch screen) , joysticks, weight sensor, axle- weight sensor in weighbridges, human gait analysis.
  • a sensor device comprising a substantially rigid member mounted with freedom to move against preset restraining forces relative to at least two sensors, and signal processor adapted to give an output indicating the nature of a movement caused by a force exerted on the member.
  • the magnetic field generator comprises conductive tracks on different layers of a multi-layer printed circuit board.
  • the conductive tracks of the magnetic field generator are associated with a transmit aerial
  • the detector comprises a receive aerial
  • the sensor element forms an intermediate coupling element between the transmit aerial and the receive aerial. ⁇ The electromagnetic coupling between the transmit aerial and the receive aerial varies with the position of the sensor element, enabling the detector to detect the position of the sensor element from a signal induced in the receive aerial.
  • the inductive sensor forms part of an interface utilising a plurality of separate sensors such as, for example a keypad.
  • Fig. 1 schematically shows a side view of a push button assembly
  • Fig 2 shows an exploded view of a rod forming part of the push button assembly illustrated in Fig 1;
  • Fig. 3 schematically shows a perspective view of a multi-layer printed circuit board forming part of the push button assembly illustrated in Fig. 1, showing a sine winding, a cosine winding and a sense winding which are formed on the multi-layer printed circuit board;
  • Fig. 4 schematically shows the variation of the respective magnetic field strength components perpendicular to the multi-layer printed circuit board produced by excitation signals flowing through the sine winding and the cosine winding;
  • Fig. 5 schematically shows the main components of signal generation and processing circuitry forming part of the push button assembly illustrated in Fig. 1;
  • Fig. 6 shows the layout of conductive tracks deposited on one side of a printed circuit board which forms part of a second embodiment of the invention, the conductive tracks forming part of a sine winding, a cosine winding and a sense winding;
  • Fig. 7 shows the layout of conductive tracks, forming part of the sine winding, the cosine winding and the sense winding, deposited on the other side of the printed circuit board illustrated in Fig. 6;
  • Fig. 8 is a plot comparing the magnetic field strength component perpendicular to the printed circuit board produced by an excitation signal flowing through the sine winding of the second embodiment with a sine function;
  • Fig. 9 is a plot comparing the magnetic field strength component perpendicular to the printed circuit board produced by an excitation signal flowing through the cosine winding of the second embodiment with a cosine function;
  • Figures 10a, b and c and 11a, b and c illustrate an alternative configuration for excitation windings
  • Figure 12 is a diagrammatic view of one embodiment of the invention employing two sensors
  • Figure 13 is a plan view of another embodiment
  • Figure 14 is a diagrammatic perspective view of part of Figure 13 and Figure 15 is a flow diagram.
  • Fig. 1 shows a push button assembly 1 in which a resiliently flexible membrane 3 is mounted to one side of a planar substrate 5, which in this embodiment is an ABS fascia panel.
  • a hole is formed through the planar substrate 5 and the membrane 3 is arranged to arc above the hole.
  • a multi-layer printed circuit board (PCB) 7 is mounted to the face of the substrate 5 away from the flexible membrane 3, and the PCB 7 has an aperture therethrough which is aligned with the centre of the hole through the planar substrate 5.
  • PCB printed circuit board
  • Conductive tracks 9 deposited on the layers of the multi-layer PCB 7 form a transmit aerial and a receive aerial as will be described in more detail hereafter.
  • the conductive tracks 9 are connected to signal generation and processing circuitry 11 which is mounted to the face of the multi-layer PCB 7 away from the planar substrate 5.
  • the signal generation and processing circuitry 11 applies excitation signals to the transmit aerial, which cause the transmit aerial to generate a magnetic field, and processes a sense signal induced in the receive aerial as a result of the generated magnetic field.
  • An elongate rod 13 is connected to the arced portion of the membrane 3 such that it projects through the hole in the substrate 5 and the hole in the multilayer PCB 7.
  • the longitudinal axis of the rod 13 is therefore substantially perpendicular to the plane of the substrate 5.
  • the rod 13 includes a ferrite element 15 which is generally aligned with the hole through the PCB 7.
  • the ferrite element 15 modifies the distribution of the magnetic field strength (i.e. the H-field) produced when excitation signals are applied to the transmit aerial in such a manner that the signal induced in the receive aerial varies in dependence upon the position of the ferrite element 15 relative to the transmit aerial and the receive aerial. Therefore, movement of the ferrite element 15 along the longitudinal axis z of the elongate rod 13, hereafter called the measurement direction, in response to a finger 17 of a user pressing the arced portion of the flexible membrane 3 can be detected.
  • the measurement direction movement of the ferrite element 15 along the longitudinal axis z of the e
  • the membrane 3 forms a hermetic seal isolating the signal generating and processing circuitry 11 from the outside of the bush button assembly 1. This is advantageous in situations where liquid or dirt may come into contact with the push button assembly 1.
  • Fig 2 shows an exploded view of the rod 6.
  • the ferrite element 15 is a elongate cylinder having an annular cross-section.
  • the length of the ferrite element 15 is 4mm and the outer and inner diameters of the annular cross-section are 3mm and 1mm respectively.
  • the rod 13 also includes a cylindrical mount having at one end a wide portion 17a, which in this embodiment has a diameter of 3mm, and at the other end a narrow portion 17b, which in this embodiment has a diameter of 1mm.
  • the narrow portion 17b passes through the hole through the middle of the ferrite element 15 in order to improve the fixing, by glue, of the ferrite element 15 to the mount of the rod 13.
  • the end of the wide portion 17a away from the ferrite element 15 is attached to a mount.
  • Figure 3 shows a perspective view of the part of the multi-layer PCB 7 on which the conductive tracks forming the transmit aerial and the receive aerial are deposited.
  • the deposited tracks are loz copper tracks which have a thickness of approximately 35 ⁇ m.
  • the multilayer PCB 7 has four laminated substrate layers 21a to 21d and five conductive track layers (the two end surfaces and the three surfaces between the four substrate layers) .
  • the multi-layer PCB 7 is referred to as a five-layer printed circuit board, where the "five" refers to the number of conductive track layers.
  • the multi-layer PCB 7 is FR4 grade circuit board with each substrate layer having a thickness of 0.5mm.
  • the aperture 23 is formed through the centre of the multi-layer PCB 7, and in this embodiment the diameter of the aperture 23 through the multi-layer PCB 7 is 4mm.
  • the transmit aerial is formed by a cosine winding 31 and a sine winding 33 which are each distributed over plural layers of the multi-layer PCB 7.
  • the receive aerial is formed by a sense winding 35 which is also distributed over plural layers of the multilayer PCB 7.
  • the ends of the cosine winding 31, sine winding 33 and sense winding 35 have been shown lifted away from the multi- layer PCB 7 in Figure 3.
  • the cosine winding 31, the sine winding 33 and the sense winding 35 are connected to the signal generation and processing circuitry 11 by conductive tracks formed on the multi-layer PCB 7.
  • the cosine winding 31 is formed by a conductive track which starts at a first terminal 37a on the surface 39 of the first substrate layer 21a and forms a first current loop 41a on the first substrate layer 21a around the aperture 23.
  • the conductive track then passes through a first via hole 43a to the surface between the second substrate layer 21b and the third substrate layer 21c, and forms a second current loop 41b around the aperture 23 on the surface between the second substrate layer 21b and the third substrate layer 21c.
  • the direction of the second current loop 41b around the aperture is opposite to the direction of the first current loop 41a around the aperture 23.
  • the conductive track then passes through a second via hole 43b to the end surface 45 of the multi-layer PCB 7 opposing the end surface 39, and forms a third current loop 41c around the aperture 23.
  • the direction of the third current loop 41c around the aperture 23 is the same as the direction of the first current loop 41a around the aperture 23.
  • the conductive track then passes to a second terminal 37b on the surface 39 of the first layer 21a through a third via hole 43c.
  • the sine winding 33 is formed by a conductive track which starts from a first terminal 47a on the surface 39 of the first substrate layer 21a and passes to the surface between the first substrate layer 21a and the second substrate layer 21b through a fourth via hole 43d, and forms a fourth current loop 4Id around the aperture 23.
  • the conductive track then passes to the surface between the third substrate layer 21c and the fourth substrate layer 21d through a fifth via hole 43e, forms a fifth current loop 41e around the aperture 23, and then passes to a second terminal 47b on the surface 39 of the first substrate layer 21a through a sixth via hole 43f.
  • the fourth current loop 41d loops around the aperture 23 in the opposite direction to the first current loop 41a
  • the fifth current loop 41e loops around the aperture in the same direction as the first current loop 41a.
  • a magnetic field is generated having an axial magnetic field component which varies along the axial direction Z with maximum values at the axial positions of the first, second and third current loops 41a, 41b, 41c and minimum values at the axial positions of the fourth and fifth current loops 41d, 41e.
  • the maximum values at the axial positions of the first and third current loops 41a, 41c have the same polarity, and have an opposite polarity to the maximum value at the second current loop 41b.
  • the magnetic field components along the axial direction Z generated by the cosine winding 31 and the sine winding 33 vary in a substantially sinusoidal manner with a period of just over 2mm, but a quarter of a cycle out of phase. The period is just over 2mm, rather than 2mm exactly, because the sine winding 33 and the cosine winding 31 do not include an infinite series of loops.
  • the sense winding 35 is formed by a conductive track which starts at a terminal 49a on the end surface 39 of the first substrate layer 21a, forms a sixth current loop
  • the conductive track then forms a seventh current loop 41g around the aperture 23, which passes around the aperture in the same direction as the sixth current loop 41f.
  • the conductive track then passes to a terminal 49b on the end surface 39 of the first layer 21a through an eighth via hole 43h.
  • the sense winding 35 is balanced with respect to both the cosine winding 31 and the sine winding 33.
  • the net electromotive force induced in the sense winding 35 by current flowing through the cosine winding 31 is substantially zero, and similarly the net electromotive force induced in the sense winding 35 by current flowing through the sine winding 33 is substantially zero.
  • the sixth current loop 41f and the seventh current loop 41g effectively form a pair of Helmholtz coils.
  • Such an arrangement has the advantage that the signal level of the signal induced in the sense winding 35 does not vary significantly with the position of the ferrite element 15, because as the signal induced in one current loop increases the signal induced in the other current loop decreases by the approximately the same amount .
  • a quadrature signal generator 61 outputs a quadrature pair of signals at a modulation frequency fi to a modulator 63, which uses the quadrature pair of signals to modulate a carrier signal, at a carrier frequency fo, generated by a signal generator 65.
  • the modulation frequency fi is 3.9 kHz and the carrier frequency f 0 is 2 MHz.
  • the pair of modulated signals are respectively input to a pair of coil drivers 67a, 67b, which amplify the modulated signals to produce an in-phase signal I (t) and a quadrature signal Q(t).
  • the in-phase signal I (t) and the quadrature signal Q(t) are respectively applied to the sine winding 33 and the cosine winding 31.
  • signals flowing through the cosine winding 31 and the sine winding 33 induce a negligible signal in the sense winding 35.
  • the ferrite element 15 causes localised bunching of the magnetic field resulting in a signal being induced in the sense winding 35 which varies with the average position Z of the ferrite element 15 along the measurement direction z.
  • an electro-motive force is induced in the sense winding 35 which results in an induced sense signal S(t) of the form: S(t) oc cos2 ⁇ f 0 cos (2 ⁇ f,t - ⁇ - ⁇ T (1)
  • the sense signal S(t) therefore corresponds to a signal at the modulation frequency fi having a phase which varies linearly with the position of the ferrite element 15 modulated by a signal at the carrier frequency fo.
  • the sense signal S(t) is input to a demodulator 69 which demodulates the received sense signal S(t), using a signal at the carrier frequency f 0 from the signal generator 65, to form a demodulated signal at the modulation frequency f x .
  • the demodulated signal output by the demodulator 69 is input to a phase detector 71, which measures the phase of the demodulated signal, and outputs the phase measurement to a position calculator 73.
  • the position calculator 73 determines the position of the ferrite element 15 from the phase measurement output by the phase detector 71.
  • the position is substantially proportional to the measured phase, and therefore the phase calculator simply multiplies the measured phase by a calibration factor.
  • the sinusoidal variation along a measurement direction z of the magnetic field strength components perpendicular to the planar substrate 5 associated with ' the cosine winding 31 and the sine winding 33 is achieved.
  • a second embodiment will now be described with reference to Figures 6 to 9 in which the five-layer PCB 3 of the first embodiment is replaced by a two- layer PCB 91, with the sinusoidal variation in magnetic field strength component perpendicular to the planar substrate 5 being achieved by a sine winding and a cosine winding formed by conductive tracks which are deposited on a first surface 93 and a second surface 95 which are on either side of the single substrate layer 91, and by through-plated via holes passing through the single substrate layer 91.
  • the two-layer PCB 91 has an aperture 97 through which the ferrite element 15 passes.
  • Figures 6 and 7 respectively show plan views of the conductive tracks deposited on the first surface
  • the two-layer PCB 91 is a 2mm thick layer of FR4 grade circuit board.
  • the conductive tracks are loz copper tracks .
  • the sine winding is formed by a conductive track which starts at a first sine terminal 101a on the first surface 93 and passes through a via hole to a first balancing winding 103a on the second surface 95.
  • the conductive track then passes to a first sine coil 105, which is formed by a first series of radially- stepped concentric arced tracks 105_1 deposited in a first quadrant of the first surface 93 with the ends of each track connected through via holes to the ends of a second series of radially-stepped concentric arced tracks 105_2 which are deposited on the second surface 95 of the two-layer PCB.
  • each of the second series of tracks 105_2 includes a kink so that the ends of each of the second series of conductive tracks are connected to respective different tracks of the first series of tracks 105_1.
  • the first sine coil 105 is a spiral conductive track about a first radial axis (with respect to the centre of the aperture 97) through the two-layer PCB 91.
  • the sine winding passes through a second sine coil 107 which is formed in a second quadrant of the two-layer PCB 91 which is opposite to the first quadrant.
  • the second sine coil 107 is formed by a first series of radially-stepped concentric arced tracks 107_1 deposited on the first surface 93 of the two-layer PCB 91 whose ends are connected through via holes to the ends of a second series of radially-stepped concentric arced tracks 107_2 deposited on the second surface 95 of the two- layer PCB 91, with a kink being provided in each of the first set of tracks 107_1 so that the ends of each of the first series of conductive tracks 107_1 are connected to respective different tracks of the second series of tracks 107_2.
  • the second sine coil 107 is a spiral conductive track formed about a second radial axis through the two-layer PCB 91 which is co-axial with the first radial axis about which the first sine coil 105 is formed, with the second sine coil 107 looping around the common axis in the opposite direction to the first sine coil 105. After the second sine coil 107, the sine winding passes to a second sine terminal 101b.
  • Fig 8 shows a plot of the magnetic field strength component perpendicular to the plane of the two-layer PCB 91 produced per unit current flowing through the sine winding, indicated by the full line 151, compared with ' a sine function having a period of 10mm, indicated by the dashed line 153.
  • the magnetic field component 151 closely matches the sine function 153 over a range of 6mm around the centre of the single-layer PCB.
  • the cosine winding starts at a first cosine terminal Ilia and passes, via a second balancing winding 103b, to a first cosine coil 113 formed by a spiral conductive track deposited on a third quadrant, which is between the first and second quadrants, of the second surface 95 of the two- layer PCB 91.
  • the cosine winding then passes through a via hole to a second cosine coil 115 formed by a spiral conductive track deposited on the third quadrant of the first surface 93 of the two-layer PCB 91.
  • the cosine winding then passes to a third cosine coil 117 formed by a spiral conductive track deposited in a fourth quadrant, which is opposite the third quadrant, of the second surface 95 of the two-layer PCB 91, and then passes through a via hole to a fourth cosine coil 119 formed by a spiral conductive track deposited in the fourth quadrant of the first surface 93 of the two-layer PCB 91.
  • Each of the first to fourth cosine coils effectively comprises a series of inner circumferential tracks and a series of outer circumferential tracks connected at their ends by radial tracks.
  • Current flowing through the inner and outer circumferential tracks respectively generate first and second parts of the magnetic field strength component along the axis of movement of the ferrite element 15 (which passes through the aperture in the two-layer PCB 91) .
  • Both the first part and the second part of the magnetic field strength component have a maximum value in the centre of the plane of the two- layer PCB 91, and decrease with distance away from the two-layer PCB 91 along the axis of movement of the ferrite element.
  • the maximum value of the first part has a greater amplitude than, and an opposite polarity to, the maximum value of the second part, but the amplitude of the second part decreases more slowly with distance from the single layer PCB 91 than the amplitude of the first part.
  • the radial tracks have substantially no effect on the magnetic field strength component along the axis of movement of the ferrite element 7.
  • the magnetic field strength component along the axis of movement of the ferrite element has a maximum value, with the polarity of the first part produced by the inner circumferential tracks, in the plane of the two-layer PCB 91, and on both sides of the two-layer PCB 91 drops through zero to a maximum value with the polarity of the second part produced by the outer circumferential fields.
  • the additional outer circumferential tracks connecting the second cosine coil 115 to the third cosine coil 117 and connecting the fourth cosine coil 119 to a second cosine terminal 111b are configured so that the magnetic field strength component along the direction of movement of the ferrite element approximates closely to a cosine function.
  • these additional outer circumferential tracks cover approximately two loops around the outside of the sine coils and cosine coils.
  • Fig 9 shows a plot of the magnetic field strength component perpendicular to the two-layer PCB 91 produced per unit current flowing through the cosine winding, indicated by the full line 161, and a cosine function having a period of 10mm, indicated by the dashed line 163.
  • the magnetic field strength component 161 closely matches the cosine function 163 over a range of 6mm.
  • the amplitude of the magnetic field strength components can be adjusted by varying the current flowing through the sine winding and the cosine winding.
  • the sense winding starts at a first sense terminal 121a on the first surface and passes, via a third balancing winding 103c, to a first sense coil 123 formed by a conductive track which loops around the aperture 97 on the second surface 95.
  • the sense winding then passes through a via hole to a second sense coil 125 formed by a conductive track which loops around the aperture 97 on to the first surface 93 in the same direction as the first sense coil.
  • the sense winding then passes from the second sense coil 125 to a second sense terminal 121b via a fourth balancing winding 103d.
  • the first sense coil 123 and the second sense 125 effectively form a pair of Helmholtz coils.
  • the first to fourth balancing windings 103 are included to ensure that, in the absence of the ferrite element 7, the sense winding is balanced with respect to both the sine winding and the cosine winding.
  • the signal generation and processing circuitry for the second embodiment is identical with the signal generation and processing circuitry of the first embodiment. Therefore, in the same manner as the first embodiment, the signal induced in the sense winding has a phase which varies in accordance with the position of the ferrite element 15 along the measurement direction.
  • the relationship between the phase of the sense signal and the position of the ferrite element 7 is approximately linear over a range of 4mm, and within that range the position of the ferrite element 7 can be determined to a resolution of approximately lO ⁇ m.
  • Figures 10a, b, c and Figures 11a, b, c show a pair of excitation windings, each of which is arranged about an axis, the axis of one being largely perpendicular to the axis of the other.
  • Figure 10a shows a side view through a planar substrate 150 showing a cross-section through the conductors 151 that form one excitation winding - a crossed circle indicates current flowing into the page, and a dotted circle indicates current flowing out of the page.
  • the arrows 152 indicate the axis of the winding.
  • Figure 10b is a plan view of the planar substrate from above, with arrows indicating the instantaneous direction of current flow in the conductors 151.
  • Figure 10c is a perspective view of the same excitation winding, showing that the axis of each winding actually lies on a cone wrapped around the perpendicular to the planar substrate 150. The view is from above, and the dashed portion indicates the turns on the lower surface of the substrate.
  • Figure 11 shows at 11a, lib and lie the same planar substrate with the other set of excitation windings 153.
  • FIG. 12 of the accompanying drawings this shows an arrangement of an input bar 200 carrying at its opposed ends a pair of sensor elements 201, 202 which can be similar to the rod 13 with its associated ferrite element 15.
  • the bar 200 is supported above a printed circuit board 203 by springs 204 so that if the bar is depressed the point at which the bar is depressed with a known force can be calculated from a ratio of the displacements of the sensor elements with respect to the printed circuit board as calculated by processing circuits similar to circuit 11 shown in Figure 1.
  • each of these inductive sensors utilise the coil configurations described with regard to the preceding embodiments.
  • FIG 13 of the accompanying drawings this is a plan view of a keypad having nine renumbered input keys.
  • This keypad is essentially formed from a single rectangular sheet 300 which corresponds to the bar 200 of the preceding embodiment but which does not undergo substantial local flexing at the various key areas indicated by the numerals 1 to 9 as it is not this local flexing which is to be measured. Instead the pad is supported as shown in Figure 14, which shows one corner of the sheet, by suitable spring arrangements 301 such as coil springs which extend between the sheet and a base plate 302. In the absence of forces on the top sheet 300 the springs 301 ensure that the sheet 300 remains parallel to the base plate 302.
  • the panel will move and tilt slightly with the direction of tilt being dependent on which button is pressed.
  • the or each sensor had a sensor element which actually passed through a hole in the printed circuit board associated with it.
  • the coil arrangement shown in Figures 6 and 7 will also provide an accurate output with respect to a sensor element the position of which merely varies with respect to the surface of the printed circuit board.
  • the multi-layer PCB 7 shown in Figure 3 in the first embodiment had four laminated substrate layers 21a to 21d and five conductive track layers (the two end surfaces and the three surfaces between the four substrate layers) whilst the PCB of the second embodiment had a two layered PCB.
  • each PCB associated with a sensor in addition to omitting the hole for each of the associated sensor elements has only the two layers as described in Figure 6 and 7.
  • the advantage of a two layer design is that it is of course cheaper 'to fabricate and the advantage of not having a hole irrespective of the number of layers is that there is more area available for the aerials. This has the result that a more linear sensor can be obtained which is also more reliable in the sense that it can give clearer and stronger signals.
  • each sensor element can be a resonator such as an LC circuit as this has the best signal to noise ratio. Additionally, using resonators it is possible to detect multiple elements simultaneously on the same sensor as the LC circuits can be constructed so that they are frequency specific.
  • the sensor elements can be a ferrous material such as a ferrite rod, disc or block or a conductive material such as a metal washer, a rod or a screw.
  • the sensor will be a non-magnetic conductor such as CU, AL or brass. The last two possibilities have the advantage of being extremely cheap.
  • the entire base plate 302 can be a single PCB, or individual PCB's can be provided at each of its corner.
  • the four sensors 303a-d at the corner of sheet 300 provide respective output signals to a processing circuit 304 which when one of the key areas on sheet 300 is depressed will give an output indicating the key.
  • the entire base plate 302 can be a single PCB.
  • the circuit 304 can be provided at a distance from the keypad or can be fabricated as part of the PCB.
  • Figure 15 is a flow diagram illustrating one of the ways in which this calculation can be carried out.
  • step SI circuit 304 measures the displacements for all four sensors 303.
  • step S2 it is checked whether or not any of the sensor outputs are above a preset threshold.
  • step S3 the decision is made as to whether the largest measured displacement is more than twice the smallest displacement. If the answer is YES, then circuit 304 outputs that key 5 was depressed in step S4. If the answer is NO, then in step S5 the decision is made as to whether the largest displacement is more than two times the second largest displacement. If the answer is YES then step S6 determines which of the sensors 303 gave the largest output and identifies that sensor as the key which was depressed. If the cursor to step S5 is NO then step S7 gives the key depressed on the basis of which pair of keys sensor outputs provided the largest two displacements.
  • the excitation signal applied to the sensor windings can be modulated by a lower frequency modulation signal in order to facilitate the use of digital processing techniques when reading and utilising the sensor outputs. This is fully described in the specification of WO 03/038379.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Input By Displaying (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

L'invention concerne des détecteurs. Dans un mode de réalisation, l'élément de couplage intermédiaire d'un détecteur inductif se déplace de manière transversale vers le plan d'une carte de circuits imprimés multicouches comportant un générateur de champ magnétique. Dans un autre mode de réalisation, plusieurs éléments de détection sont montés sur un élément sensiblement rigide.
PCT/GB2004/002094 2003-05-14 2004-05-14 Appareil de detection WO2004102370A2 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
GB0311098A GB0311098D0 (en) 2003-05-14 2003-05-14 Touch sensor
GB0311098.8 2003-05-14
GB0322585.1 2003-09-25
GB0322585A GB0322585D0 (en) 2003-09-25 2003-09-25 Planar user interface
US10/724,336 2003-11-29
US10/724,336 US7196604B2 (en) 2001-05-30 2003-11-29 Sensing apparatus and method

Publications (2)

Publication Number Publication Date
WO2004102370A2 true WO2004102370A2 (fr) 2004-11-25
WO2004102370A3 WO2004102370A3 (fr) 2005-10-13

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WO (1) WO2004102370A2 (fr)

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WO2007121740A2 (fr) * 2006-04-26 2007-11-01 Soehnle Professional Gmbh & Co. Kg Dispositif dynamométrique
CN103091002A (zh) * 2012-01-13 2013-05-08 骏升科技(中国)有限公司 电容式压力传感转换装置及在低端单片机上实现电容式压力传感的方法
CN108801537A (zh) * 2018-08-30 2018-11-13 中山优感科技有限公司 一种微压力值传感器及其制备方法
US10527457B2 (en) 2015-02-27 2020-01-07 Azoteq (Pty) Ltd Inductance sensing
KR20200105251A (ko) * 2019-02-28 2020-09-07 (주)파트론 터치센서 모듈
WO2023235141A1 (fr) * 2022-06-01 2023-12-07 Google Llc Détection d'état de broche à ressort

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WO1999061868A1 (fr) * 1998-05-22 1999-12-02 Synaptics (Uk) Limited Detecteur de position
WO2002097374A1 (fr) * 2001-05-30 2002-12-05 Gentech Investment Group Ag Procede et appareil de detection
WO2003038379A1 (fr) * 2001-10-30 2003-05-08 Gentech Investment Group Ag Appareil et procede de detection
WO2003038380A1 (fr) * 2001-10-30 2003-05-08 Scientific Generics Limited Detecteur de position

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DE3904702C1 (en) * 1989-02-16 1990-07-26 Messerschmitt-Boelkow-Blohm Gmbh, 8012 Ottobrunn, De Keyboard with definable keys
GB2316177A (en) * 1996-08-06 1998-02-18 John Richards Rigid plate touch screen
WO1999061868A1 (fr) * 1998-05-22 1999-12-02 Synaptics (Uk) Limited Detecteur de position
WO2002097374A1 (fr) * 2001-05-30 2002-12-05 Gentech Investment Group Ag Procede et appareil de detection
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WO2003038380A1 (fr) * 2001-10-30 2003-05-08 Scientific Generics Limited Detecteur de position

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007121740A2 (fr) * 2006-04-26 2007-11-01 Soehnle Professional Gmbh & Co. Kg Dispositif dynamométrique
WO2007121740A3 (fr) * 2006-04-26 2007-12-06 Soehnle Professional Gmbh & Co Dispositif dynamométrique
US7908933B2 (en) 2006-04-26 2011-03-22 Soehnle Professional Gmbh & Co. Kg Load gauge
CN103091002A (zh) * 2012-01-13 2013-05-08 骏升科技(中国)有限公司 电容式压力传感转换装置及在低端单片机上实现电容式压力传感的方法
US10527457B2 (en) 2015-02-27 2020-01-07 Azoteq (Pty) Ltd Inductance sensing
CN108801537A (zh) * 2018-08-30 2018-11-13 中山优感科技有限公司 一种微压力值传感器及其制备方法
CN108801537B (zh) * 2018-08-30 2024-04-12 中山优感科技有限公司 一种微压力值传感器及其制备方法
KR20200105251A (ko) * 2019-02-28 2020-09-07 (주)파트론 터치센서 모듈
KR102264320B1 (ko) * 2019-02-28 2021-06-14 (주)파트론 터치센서 모듈
WO2023235141A1 (fr) * 2022-06-01 2023-12-07 Google Llc Détection d'état de broche à ressort

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