WO2007147115A2

WO2007147115A2 - Capacitive sensors allowing contact detection of non-conducting objects

Info

Publication number: WO2007147115A2
Application number: PCT/US2007/071346
Authority: WO
Inventors: Robert T. Fergusson
Original assignee: Invisa, Inc.
Priority date: 2006-06-15
Filing date: 2007-06-15
Publication date: 2007-12-21
Also published as: WO2007147115A3

Abstract

An example apparatus for sensing of both electrically conducting objects (such as persons) and electrically non-conducting objects (18) comprises a sensing element (16), the apparatus being operable to sense a conducting object proximate to the sensing element using capacitive coupling between the sensing element and the conducting object. The apparatus is further operable to sense physical contact with an object, whether electrical conducting or not using a movement of the sensing element ( 16) relative to a reference conductor, the relative movement being induced by physical contact between the object and the sensing element or an element mechanically coupled with the sensing element. The sensing element may be supported by a deformable structure (14) so that the movement of the sensing element is facilitated by deformation of the deformable structure. Example apparatus may be used with automatic doors (10), gates, and other closures.

Description

CAPACmVE SENSORS ALLOWING CONTACT DETECTION OF NON-CONDUCTING OBJECTS

REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from U.S. Provisional Patent Application Serial No. 60/813,983, filed June 15. 2006. the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to sensors, in particular to capacitive sensors for closures such as doors.

BACKGROUND OF THE INVENTION

[0003] Conventional capacilϊve sensors are used as proximity sensors for conducting objects, and can be used to stop an automatic door from hitting a conducting object. However, such conventional apparatus may not detect a non-conducting object. Hence, two separate sensor apparatus arc conventionally required; a capacitive sensor for detecting conducting objects, and a separate contact sensor for detecting non-conducting objects. However, using separate sensors increases costs and lowers reliability. Hence, there is a need for a sensor which detects both conducting and non-conducting objects.

SUMMARY OF THE INVENTION

[0004] Embodiments of the present invention include capacitive sensors that combine the functionality of a non-contact sensor for conductive objects with that of a contact sensor for non- conductive objects.

[0005] A capacitive sensor may be used to stop the motion of a moving door if an object is in the path of the door. For example, physical contact with the object can modify the capacitive coupling between an antenna and a second conductor.

[0006] As the door contacts a non-conductive object, the antenna is forced towards the metal door. The change in capacitive coupling between the antenna and the door can be detected using an electronic circuit, allowing it to trigger the sensor. Hence, an example apparatus can operate as a non-contact sensor for conductive objects and a contact sensor for non-conductive objects. An example apparatus can work as a contact sensor for any object, including conducting objects, but the motion oi the closure can be stopped before contact with the conducting object. A signa! processing electronic circuit used to detect the change in capacitive coupling, for example from a change in oscillator frequency, may be similar to those described in our other patent applications directed to capacitive sensing of conducting objects.

[0007] Embodiments of the present invention include capacitive sensors that combine the functionality of a non-contact sensor for conductive objects with that of a contact sensor for non- conductive objects.

[0008] A capacitive sensor may be used to stop the motion of a moving door if an object is located in the path of the door. For example, physical contact with the object can modify a capacitance between an antenna and a second conductor. As the door contacts the object, the antenna is forced towards a second conductor, which maybe metal within the door itself. The change, in this example an increase, in capaciiive coupling between the antenna and the door can be detected using an electronic circuit. The electronic circuit provides an output signal when an object is sensed, and the output signal can be used to modify operation of the door (for example, reverse direction). The same antenna can be used in a capacitive proximity sensor for conducting objects proximate to the door.

10009] Hence, an example apparatus can work as a non-contact sensor for conductive objects and a contact sensor for non-conductive objects. An example apparatus may work as a contact sensor for any object, including conducting objects, but the motion of the door can be stopped before contact with a conducting object if capacitive proximity sensing is used. An electronic circuit used to detect the change in capaciiive coupling due to contact with an object may be similar to one described in our other patent applications directed to capacitive proximity sensing of conducting objects. A single electronic circuit can be used for proximity sensing and contact sensing of objects.

[OOIOJ An example apparatus, operable to provide capacitive sensing of both electrically conducting objects and electrically non-conducting objects, comprises an electronic circuit including a signal processing circuit and an oscillator circuit, and a sensing element in electronic communication with the oscillator circuit. The sensing element may be an elongated electrical conductor, such as a metal wire, strip, or tube, and may be referred to as an antenna. The apparatus is operable to sense a conducting object proximate to the sensing element using a capacitivc coupling between the sensing element and the conducting object. The apparatus is further operable to sense an object (including non-conducting objects) due to physical contact between the object and either the antenna itself or a component to which the antenna is attached. The physical contact induces sensing element movement relative to a reference conductor so as to modify capacitive coupling between the sensing element and the reference conductor. The sensing element may be supported by a deformable structure that facilitates movement of the sensing element relative Io the reference conductor, which may be a metal door or metal gate. 10© 1 1 J Examples of the present invention also include water diverters configured so as to divert water away from a sensing clement.

BRIEF DESCRIPTION OF THE DRAWINGS

|OO12J Figures IA - I B shows an astragal and antenna fin this example, a metal strip) collapsing towards a grounded door;

|0013] Figures 2A - 2B show an astragal and antenna collapsing towards a grounded reference conductor supported by an inner loop;

[0014] Figure 3 shows a configuration with an antenna and foam backing; [0015] Figure 4 shows an astragal having an antenna in a chamber within the astragal; [0016] Figure 5 shows an antenna molded into an astragal; [0017] Figure 6 shows a metal strip within a chamber within a rubber bumper; [0018] Figures 7A - 7B illustrate an astragal and antenna connected to a capacitive sensor. further including a resistor for fail-safe detection;

[0019] Figure 8 illustrates an astragal with an open structure with the antenna including a metal strip extruded into the astragal material:

[0020J Figure 9 illustrate a configuration using a rigid antenna supported by flexible insulating mounting blocks; [002J] Figures 1 OA - 1 OB illustrate a potential problem caused by flowing water:

[0022] Figures 1 I A - 11C illustrate astragals having water diverters;

[0023] Figure 12 shows a water di verier formed as part of the astragal holder;

[0024] Figure 13 shows a water diverter supported between the astragal holder and the door;

[0025] Figure 14 shows a water diverter attached to a side of the door;

[0026] Figure 15 shows a water diverter clamped between brackets at the bottom of a rolling door; l0027| Figure 16 shows an astragal having a water diverter clamped between brackets at the bottom of a rolling door;

[00281 Figure 17A - 17B show an astragal having an end seal to prevent water entering the interior of the astragal; and

[0029] Figure 18 illustrate the use of end seals to prevent water from entering an astragal attached to a gate.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In examples of the present invention, an antenna (such as a melai strip) is supported by a deformabie structure (such as an astragal) attached to an edge of a door. An astragal is a deformable structure, such as a rubber end seal. The antenna and astragal are configured so that if there is physical contact made with an object, then the movement of the antenna towards the door causes a detectable change in capacitive coupling between the antenna and a reference conductor. The reference conductor may be the door itself, particularly if the door comprises metal. The change in capacilive coupling is delectable by a similar electronic circuit as used to detect the proximity of conducting objects, and the same electronic circuit can be used to detect both conducting and non-conducting objects. Electrically conducting objects may be detected before physical contact is made due to capacitive coupling between the antenna and the conducting object. However, an object detected by deformation of the astragal may be any object, including a non-conductive object that is not normally be detected by proximity sensing using a conventional capacitive sensor. [0031] In an example of the present invention, a curved 3/4" wide metal strip acting as an antenna for a capacitive sensor was placed in the bottom of a generally circular astragal on the bottom of a residential garage door. When the door was closing, the presence of a conductive object such as a person^'s hand caused the door to reverse before it contacted the hand. A non- conductive plastic object was then placed in the path of the door, and contact with the plastic object was detected using the change in capacitive coupling between the antenna and the door. Shortly after contact with the object, the signal from the antenna was strongly affected by the movement of the antenna towards the door, causing the sensor to trigger a reversal of the door. [0032] Movement of an antenna relative to a reference conductor modifies the capacitive coupling between the antenna and reference conductor. The reference conductor may be any grounded electrically conducting object, which may be part of the door, otherwise attached to the door, supported by an astragal, or otherwise mechanically coupled to the door. For example, (he door itself may be grounded, so that any movement of the antenna towards the door modifies the capacitive coupling between the antenna and the door. In another example, a grounded metal strip may be attached to the edge of a door, for example the edge of a non-conducting door. The reference conductor may be a metal strip located proximate to or within the astragal, so that deformation of the astragal modifies the capacitive coupling between the antenna and the reference conductor.

[0033] Conductive objects may be detected before physical contact from the modification of the antenna field due to capacitive coupling between the antenna and the conductive object. Capacitive sensors for detection of conducting objects are described in our issued patents and co- pending applications. An example capacitive sensor comprises an oscillator, such as a tank circuit, and an antenna electrically coupled to the oscillator. Capacitive coupling between the antenna and a proximate conducting objecl modifies the oscillator frequency, and the frequency change is detected by an electronic circuit. For example, the resonant frequency of the oscillator may be compared with a reference frequency. Optionally, a difference frequency may be determined. A measured frequency change, for example greater in magnitude than a predetermined threshold, allows non-contact remote sensing of conducting objects. [0034] Some safety standards require that non-conductive objects be detected when a door, such as an automatic door, is closing. Conventional capackive sensors fail to detect non- conductive objects, and hence two types of sensors are conventionally required: a sensor for non- contact sensing of conductive objects, which provides safer operation of closures, and a second sensor for contact sensing of non-conductive objects. However, embodiments of the present invention allow detection of both conducting and non-conducting objects using a single antenna and an electronic circuit, and hence may be no more complex than a conventional sensor for detection of conducting objects alone. Hence, such safety regulations can be met using a single sensor according to an embodiment of the present invention, having an antenna and an electronic circuit operable to measure eapacitive coupling changes related to the antenna. The detected changes in eapacitive coupling may be due to eapacitive coupling between the antenna and a proximate conducting object, or a capacilive coupling between the same antenna and a reference conductor that is modified by contact between an astragal and any object (conducting or nonconducting). The antenna and reference conductor are supported so that, absent physical contact with other object, the eapacitive coupling between them is substantially unchanged as the door moves. An electronic filler in the sensing electronic circuit may be used to eliminate the effect of slow drifts in the eapacitive coupling, for example due to temperature changes, humidity changes, other presence of moisture, other ambient condition changes, or to compensate for other drifts or changes in the eapacitive coupling.

[00351 Embodiments of the present invention include eapacitive sensors that combine the functionality of a non-contact sensor for conductive objects with that of a contact sensor for non- conductive objects. Conductive objects are detected by their effect on the antenna field (using an antenna in communication with an oscillator) due to a change in a first eapacitive coupling, and non-conductive objects are detected by a change in eapacitive coupling between the antenna and a reference conductor {such as a grounded conductor that is part of a door), due to a relative positional change induced by contact with the non-conducting object.

[0036] The antenna can be configured so that the eapacitive coupling between the antenna and a reference conductor is modified by physical contact between an object and a component. such as an astragal, mechanically associated with the door. For example, the physical contact may deform the astragal, and urge the antenna closer to the reference conductor. Physical contact may occur between the object and the antenna itself, any componenf associated with the antenna, or any other component movement of which is capable of inducing a change in capacitive coupling between the antenna and the reference conductor. In some examples, the antenna is supported by an astragal, and For example, the contact may force the antenna closer to the second conductor.

[00371 The antenna may be an elongated electrical conductor, .such as a metal strip, wire, metal lube, conducting polymer tape, and the like. The antenna may support an insulating layer along some or all of its length. A metal antenna can be extruded into a flexible astragal material, secured to the inside of the astragal using a flexible foam material or using retaining edges or a chamber extruded into the astragal. A rigid metal antenna such as a metal tube can be mounted such that non-conductive mounting brackets or insulating blocks allow the antenna to move towards the door to which it is mounted.

[0038] The antenna, such as a metallic strip, may be configured on an astragal or seal on a closure so that when an object fsuch as a non-conductive object) contacts the antenna, the antenna is moved towards a reference conductor {such as a metallic door component), inducing in change in capacitance between the antenna and reference conductor, the change in capacitance being used to detect contact with the object.

(0039 J The reference conductor may be a metal strip, wire, part of the door itself, or other conducting component. The antenna and reference conductor may be both supported so that the capacitance between them does not change substantially unless physical contact is made with an object. A substantial change may relate to a parameter change greater than a threshold value within a predetermined time interval, the predetermined time interval may be on the order of seconds (for example, in the range 0.001 - 5 seconds),

10040] When a door approaches its closed position, the door typically nears a grounded object such as the ground itself or a metal post, and a conventional capacitive proximity sensor is normally disabled to prevent false tripping of the sensor. For proximity sensor detection of a conductive object this need not be a problem because the sensing field of the antenna moves with and precedes the leading edge of the closure. Hence, a conducting object will be detected before the senior field is cut off or ignored by a sensor electronic circuit. For non-conductive object detection, the sensitivity may instead be significantly reduced over a portion of travel near the closed position, to reduce the influence of a heavily grounded structure while still allowing contact sensing of objects. Sensitivity may be reduced within, for example, 1.5 inches of the fully closed position.

[0041] In some examples, the antenna is supported by an astragal. In this context, an astragal is a deformable structure supported along an edge of a door or other closure, typically presenting one or more convex surfaces as seen when looking towards an approaching edge of the door. The cross-sectional form of the astragal may be one of various possible shapes, such as generally U- shaped (the ends of the "U" being more proximate to the edge of the door), circular, generally L- shaped. rectangular, square, or other cross-sectional form. The astragal may provide sealing of closed doors, and reduce the force of impact with objects in the path of the door. [0Θ42J Astragal material can be elastic or resilient, such as natural or synthetic rubber, polymer, and the like. The astragal material is preferably not electrically conductive, at least not so an electrically conductive path exists between the antenna and the second conductor. Some black astragal materials use carbon as a filler or coloring agent. A conductive astragal material may provide a partially conductive path between the grounded door and the antenna which may cause erratic door operation. A door, if used as the second conductor, is preferably properly grounded so that the capacitive coupling to the antenna is generally constant in the absence of mechanical deformations of the astragal or other structure.

(00431 An earth ground connection may be provided from the sensor electronic circuit to the door to prevent this condition. This can be done by providing a separate ground connection from the antenna to the door, or if the sensor is mounted on the moving door, providing a connection from its earth ground to the door.

(0044J Further embodiments of the present invention include improved designs of sensing element (e.g. an antenna) for a capacitive sensing apparatus to be used on doors that eliminate false tripping from water or rain that would cause streams of water to flow between the metal door and the sensing antenna, for example in a capacitive sensing apparatus that is attached to the bottom of an overhead door. [00451 The figures illustrate several possible methods of supporting a sensing antenna proximate to the edges of a closure. In most examples, the closure is a door. However, the configurations discussed may be readily implemented for any type of closure, such as a door (including sliding doors, garage doors, and the like), gates, barriers, windows, and the like. [0046] The antenna may be supported by a deformable structure attached to an edge of the closure. The deformable structure may be an astragal, such as an astragal presenting a generally convex surface to an object in the path of the door. The deformable structure may also be a bumper. The deformabie structure may be pre-existing, and the antenna attached using any convenient mechanism, such as an adhesive. Alternatively, the deformable structure may be manufactured so as to include the antenna, for example as an elongate electrically conducting element {such as a metal strip, wire, lube, and the like) within an extruded resilient and deformable structure. For example, a metal strip may run the length of an astragal, and may be included as the astragal is excluded. The antenna may comprise any elongated conductor, and may run some or all of the way along an astragal or other component mechanically associated with the closure.

JΘ047] Figure IA shows, in cross-section, a metal door 10 having an astragal 14 attached to an edge of the door by astragal support 12. An antenna 16 is supported by the astragal. Conductive objects in the path of the door can be detected by the effect on the electromagnetic field produced by the antenna, for example if the antenna is coupled to an electronic oscillator, allowing contact with conducting objects to be prevented. For example, capacitivc coupling between the antenna and a proximate conducting object, such as a person, can modify the oscillator frequency, which may then be detected electronically. Hence, contact with conducting objects may be prevented by capacitivc proximity sensing. However, in a conventional sensor, there may be no detectable capacitivc coupling between the antenna and a non-conducting object proximate to the antenna, and hence proximate to the edge of the door and possibly in the path of the door.

[0048J Figure I B illustrates that when the outside surface of the astragal, typically the portion of the astragal most distal from the door edge, contacts a non-conducting object, physical deformation of the astragal causes the capacitivc coupling with the door to increase as the antenna moves closer to the door edge. The antenna itself may be deformed, or may be fairly rigid. The capacitor symbols (20) are for illustrative purposes only, and do not represent actual components.

[0049J In this example, as the door begins to contact an object 18. the antenna 16 is forced towards the metal door 10, and the increase in capacitive coupling with the door (the second conductor in this example) can then used to sense the contact, triggering the sensor. Motion of the door may then be stopped. The sensor may operate as a non-contact sensor for conductive objects (using proximity sensing) and a contact sensor for non-conductive objects. The sensor may also operate as a contact sensor for conducting objects, if for some reason proximity sensing is not used or malfunctions.

[00501 The change in capacitive coupling can be detected as the change in frequency of an oscillator, such as an LC tank circuit, to which the antenna is electrically coupled. Hence, the change in capacitive coupling results in a change in oscillator frequency, and this is delectable using an electronic circuit.

[0051] For high speed automatic doors, there is a risk of damage being incurred before the door has a chance to stop and reverse. One approach to lessen the damage is to increase the size of the astragal so that it extends further out from the edge of the door. However, this may reduce the baseline (no deformation) capacitive coupling between the antenna and the door. Hence, the astragal or leading edge bumper may have a second conductor, such as a grounding strip (a grounded metal strip) placed between the antenna and the edge of the door.

[0052] Figure 2 A shows a metal door 10 having an astragal 26 attached to one edge by an astragal support 20, in this example the antenna 28 being a metal strip supported by the astragal

26. The door edge also support an inner loop 22, which may be similar to the astragal and is contained within the astragal, and inner loop supports a reference conductor 24, in this case a grounded metal strip.

[0053] Figure 2B shows that if the astragal contacts an object such as non-conductive object

18, deformation of the astragal increases the capacitive coupling between the antenna 28 and the grounded metal strip 24. In this example, the grounded metal strip is supported by the inner loop within the astragal. This configuration allows an astragal to extend further from the edge of the door, and allows contact with an object to be sensed at larger distances from the edge of the door. JϋO54| The antenna may be an adhesive-backed flexible metal strip applied to, for example. the inside surface of an astragal. Alternatively, a chamber or groove may be extruded into (or otherwise formed in) the astragal, and an antenna in the form of a rigid metal strip or rod slid into the chamber or groove. A wire can be used to connect the antenna to the sensor circuit. The antenna may be partially or fully insulated, for example to prevent the antenna shorting against another electrical conductor, such as the door, a metal extrusion holding the antenna, or other electrical conductor. If the sensor circuit detects a shorted antenna, this may cause a failsafe condition (e.g. doors fully open or closed, and inoperative). The antenna insulation may comprise any non-conductive material, such as a sleeve, tape, or foam.

Ϊ0055] Figure 3 shows a configuration similar to that discussed above in relation to Figure 1 , further including a foam insert 30 within the astragal 14, the antenna 16 being supported by the astragal. A foam material, for example having a generally cylindrical form, may be attached Io a metal strip, and inserted into the hollow chamber of an astragal so that the metal strip acts as an antenna. The foam acts to keep the strip from moving around or vibrating while the door is opening and closing, and is located within the astragal between the antenna and the door. The metal strip may be more rigid than the foam and the astragal material.

I0056J Figure 4 shows another configuration similar to Figure 1 , with door 10 and astragal support 12. In this example, the astragal 40 has a chamber 44 formed therein, the antenna 42 being located within the chamber 44. The antenna may be a metal strip that may be slid into the chamber during the assembly.

[0057] An astragal may have a groove, chamber, or other structure extruded or otherwise formed therein to support the antenna. The astragal material may help electrically insulate the antenna from the surroundings.

[0058J Figure 5 shows a configuration similar to Figure 1, in which an antenna 52 is a metal strip molded into an astragal 50. Molding and extrusion processes may be used to mold the antenna directly into the astragal.

] ] [0059] Figure 6 shows a bumper 60 having a side groove 64, the configuration of the side groove in part determining how the bumper collapses under pressure. In lhis example, the antenna 68 is a metal strip is located within the distal portion of the bumper, running through an elongate chamber within the astragal material. In this context, distal refers to a portion most distant from the door edge on which the bumper is located. The bumper may be formed of rubber or other material. The eϊongate chamber may be formed during extrusion of an astragal.

[0060] A bumper may have one or more wail narrowings (such as grooves, indentations, or other form of wall narrowings) to control how the bumper collapses under pressure.

[0061] Another example uses an existing safety edge bumper extrusion that has a tape sensor already extruded into the extrusion, using the tape sensor as the antenna. The antenna input from the sensor circuit may be electrically attached to the metal contact(s) of the tape switch.

[0062] Figures 7A - 7B show a configuration similar to Figure 1, illustrating how the antenna may be connected to a capacitive sensor electronic circuit within apparatus housing 78.

Figure 7A shows a cross-section of the astragal. The sensor electronic circuit includes an antenna signal processing circuit 80. A failsafe resistor 74 is connected in series using a conductor 72, as shown in the figures.

|0063] Figure 7B shows a cable 76 used to electrically connect the antenna to the electronic circuit, in this example using the shielded center conductor of a coaxial cable. The grounded shielding of the cable is connected to the reference conductor, in this example the metal door.

The figures show electrical connection tabs bolted to the antenna, shown at 70 in Figure 7A.

Flowever, any electrical connection may be used.

[0064J Figure 8 shows a cross-section of a configuration using an open astragal 92 supported by door 90, a metal strip antenna 94 being extruded into the open astragal.

[0065J Figures 9A - 9B show a configuration using a rigid antenna 104 attached to the edge of a door 100 using flexible non-conducting mounting blocks such as 102. A number of such mounting blocks may be used along the edge of the door. In this example, the antenna is a metal tube. Figure 9A is a cross-section, and Figure 9B a side view. [0066] The ends of an astragal (or any other edge seal or structure supported by the edge of the door) may be sealed lo prevent the ingress of water into the astragal. Holes or other drainage mechanism may be used to allow accumulated water to drain from an astragal. f 00671 For an antenna on the bottom of a garage door, heavy rain may cause a continuous stream of water to occasionally form between a metal portion of the door and the area where the antenna is located. This modifies the capacitance between the antenna and the grounded door. 10068] There may not normally be a problem with the w^rater coating the antenna covering which can occur when the antenna assembly is in contact with the wet ground or is coated from a light drizzle of rain. These may cause a gradual change in the operating frequency of the sensor which can be compensated for in a properly designed processing circuitry. However, when a heavy stream of water bridges between the grounded metal door and the antenna area, a sudden shift of frequency can occurs that is similar to a shift caused by the antenna approaching a grounded object, even though the antenna may be insulated from the water, [0069] Another problem can occur if water enters the end of the astragal and accumulates on or near the antenna. As the door moves it may cause a shift of the water which will cause a sudden shift of frequency. Another problem can occur if the water contacts the bare metal of the antenna causing a high impedance conductive path between ground and the antenna. 10070] Further embodiments of the present invention include designs that prevent a continuous stream of water flowing between the garage door and the antenna area, and which also prevent water from entering the astragal from any openings and thereby affect the signal at the antenna of a capacitive sensing apparatus.

[0071] Figures 1OA - H)B show a stream of water 1 18 formed over the door 110, astragal support 1 12. and astragal 1 14, the stream of water running proximate to the antenna 1 16. Figure 1 OA shows the astragal in cross-section, and Figure I OB shows lhc exterior surface {usually termed the front) of the door.

[0072] In configurations where the antenna is located within an astragal, a water stream may be broken up by one or more of several possible approaches. One or more divertcrs can be used to prevent a stream of water bridging between the door and the antenna. This has useful application in overhead doors with capacitive sensing edge detectors placed at the bottom of the door and where the doors may be subjected to large amounts of water (for example, from rainstorms, sprinklers, gutter run-off, and the like). The astragai may be sealed at each end, for vertical or horizontal applications, and helps prevent water from providing a direct conductive path between the door and the antenna when water is present. j0073] False triggering of a capacitive sensor using an antenna located near the bottom edge of a door may be reduced by sealing the ends of the astragal, breaking up water flow over the door and/or astragal using diverters, and allowing any trapped water to drain away rapidly. A grounded conductive stream of water can be prevented from forming near the antenna by breaking up the stream before it reaches the bottom of the astragal. Water may also be prevented from entering the ends of the astragal where it could accumulate and causing a shift in the capacitance as the accumulated water is put into motion by the movement of the door. If the antenna is an exposed piece of metal, preventing water ingress into the astragal prevents intermittently shorts to ground through an impedance path created by the water. There are several possibilities approaches.

|0074| Figures HA - HC show configurations similar to that of Figure 10, using astragals having extruded water diverters. Figure 1 IA shows a door 110, astragal holder 1 12, and antenna 1 16, as in Figure 10, but using an astragal 120 having water diverters such as 122. The antenna is protected from water by internal member 124, and held in groove 126. A stream of water 128 is broken up by a diverter into separate droplets, greatly reducing the effect on the antenna signal. [0075] Figure 1 I B shows a simitar configuration to Figure 1 IA, using an astragal having two diverters per side. For a moderate water flow, a single diverter 134 is sufficient to break up the flow. As shown in Figure HC, for heavy water flow a second diverter 136 is used to break up then water flow.

[Θ076J A diverter may be a fin-like structure, presenting an upper surface sloping down and away from the body of the astragai. A diverter may be any structure, such as a protrusion, that divert a stream of water away from the portion of the astragal housing the antenna. In some examples, diverters are only present on the same side of the door as is exposed to outside elements, such as rain. [0077] Figure 12 shows a water divcrler 142 provided by an extension of the astragal holder 140. An astragal holder may be an aluminum extrusion used to hold the astragal, and in this example further includes a water diverter extending away from one side of the door so as to divert a flow of water down the door away from the astragal. Other components are as described above in relation to Figure 10. The astragal holder as an extension providing an upper surface that diverts water flow away from the astragal, so that the water lends to fall as separate droplets to the ground without flowing over the astragal.

10078] Figure 13 shows a configuration similar to Figures 12, in which a separate diverter 150 is held against the bottom of the door. The diverter may be a rubber (or other insulator, such as plastic) extrusion attached to the door, or an aluminum or other metal extrusion. Other components are as described in relation to Figure 10.

|0079] Figure 14 shows another configuration similar to Figure 10. having a separate diverter attached to the side of the door. Other components are as described in relation to Figure 10. (0080] Figure 15 shows a separate diverler 176 used with a roiling door 170, having a bottom portion 172. The diverter 176 is clamped, using a bolt assembly, between brackets at the bottom of the rolling door, between the aluminum extrusion 172 and the door 170. The diverter may be a rubber or flexible plastic deflector, or a metal fin such as extruded aluminum. [0081 ] Figure 16 shows an astragal 190 with extruded diverter fins such as 192 and 194, used with a rolling door similar to that shown in Figure 15. A water flow successively encounters first and second dtverters 192 and 194, and is broken up into a discontinuous flow. f0082| If a diverter allows significant amounts of water to accumulate on top of the diverter, this water may be connected to the door through a water stream that could cause the accumulated water to affect the antenna field. The diverters may be situated far enough away from the antenna to largely prevent this.

[0083] Water may wick up under the diverter and bridge over the underneath side of the diverter and astragal. The angle and shape of the diverter may readily be configured to prevent this from occurring.

[0084[ Figures 17A - 17B show a configuration similar to Figure 1 ] B, with door 200, astragal 202 having diverters, and antenna 204. An end seal 206 on each end of the astragal may be used to prevcnl water ingress into ihe interior space of the astraga!. Figure 18B further shows an electrical connection 208 to the antenna.

10085] Figures 18A - 18B show a gate 220 with an astragal 222 (in this case, a collapsible extrusion) at the edge of the gate, with antenna 224 generally disposed vertically, and end seals such as 226 at top and bottom of the collapsible extrusion. Sensor electronic circuit may be located within housing 228, supported by the gate.

[0086] Configurations to minimize the effects of water can be used with any capacitive sensor, including those only used for detection of conducting objects using capacitive proximity sensing.

[0087] In an experiment, an astragal with an antenna was attached to the bottom of a door section and sprayed with water. False triggering of the capacitive center was observed as the water streams formed a bridge between the door panel and the area where the antenna was located. Various configurations of diverters were designed, such as described herein, that broke up the water stream before it reached the bottom of the astragal where the antenna was located. Breaking up the water stream was found to prevent the false triggering of the sensor. (0088] Hence, a capacitive sensor comprises an antenna, the capacitive sensor detecting a conducting object through a capacitive coupling between the antenna and a proximate conducting object, the capacitive sensor further detecting a non-conducting object using a movement of the antenna induced by contact with the non-conducting object. Contact between an object and a deformable structure supported by the edge of the door induces motion of the antenna, and changes the relative position and hence capacitance between the antenna and a proximate reference conductor. Movement of the antenna may be relative to the reference conductor, such as a grounded conductor. In applications where the antenna is supported by a closure, such as a door or gate, the grounded conductor may be part of the closure or otherwise supported thereon.

[0089] Sensor apparatus may be used with the antenna supported proximate to the edge of any closure, such as the bottom edge of commercial or residential doors, the closing edge of sliding doors having an edge seal, the leading and/or trailing edge of slide gates, and the bottom edge of vertical pivot gates. Applications are not restricted to closures, as sensors according to the present invention may be used in any application where sensing of conducting and nonconducting objects is desired.

[0090] Examples described herein describe sensors operating with doors, though such examples may be adapted for use with all types of closures, such as gates, barriers (such as swing barriers), and the like.

[0091] Embodiments of the present invention may also be adapted for use with mobiie apparatus, for example to prevent collision of the mobile apparatus with an object. For example, a mobile apparatus (such as a robot, vehicle, cart, and lhe like) may have a deformabie structure attached thereto, the deformable structure supporting an antenna. Motion of the apparatus may be stopped, slowed, or re-directed through operation oi a steering mechanism and/or brakes when a conducting object or non-conducting object is detected.

[0092] In some examples oϊ the present invention, sensor triggering due to conducting and non-conducting objects may be distinguished, and the apparatus enter one of a plurality of modes due to such triggering. Applications further include material sorting of objects on a conveyer belt.

[0093] Example apparatus may further include a plurality of antenna, so as to provide spatial information related to fhe position of the detected object. The plurality of antenna may be supported on a single deformabie structure, or each antenna be supported by its own deformable structure, or other configuration used.

[0094] An example apparatus comprises a sensing electronic circuit including a signal processing circuit and an oscillator circuit. At least one sensing element, which may be termed an antenna, is in electronic communication with the oscillator circuit, and the oscillation frequency of the oscillator circuit can be modified by capacitive coupling between other objects and the sensing element. The sensing element may be for example an elongated electrically conducting element. The apparatus may further include a grounded power supply operable to energize the eleclronic circuitry.

[0095] An example capacitive sensor apparatus comprises an antenna, the capacitive sensor detecting a conducting object through a capacitive coupling between the antenna and the conducting object, the capacitive sensor further detecting a non-conducting object using a movemcnl of the antenna induced by the non-conducting object. The movement of the antenna induced by the non-conducting object may be a movement of the antenna relative to a grounded conductor. In some examples, the antenna is supported proximate to an edge of a closure by a deformabie structure.

[0096| Patents, patent applications, or publications mentioned in this specification are incorporated herein by reference to the same extent as if each individual document was specifically and individually indicated to be incorporated by reference.

|0097] The invention is not restricted to the illustrative examples described above. Examples are not intended as limitations on the scope of the invention. Methods, apparatus, compositions, and the like described herein arc exemplary and not intended as limitations on the scope of the invention. Changes therein and other uses will occur to those skilled in the art.

I S

Claims

] . An apparatus operable to provide sensing of objects, including both electrically conducting objects and electrically non-conducting objects, the apparatus comprising: an electronic circuit, the electronic circuit including a signal processing circuit and an oscillator circuit, the oscillator circuit having an oscillator frequency; and a sensing element, in electronic communication with the oscillator circuit, wherein the apparatus is operable to sense a conducting object proximate to the sensing clement using a first capacitive coupling between the sensing element and the conducting object, the apparatus being further operable to sense physical contact with an object, the physical contact inducing a movement of the sensing element relative to a reference conductor so as to modify a second capacitive coupling between the sensing element and the reference conductor, the sensing element being supported by a deformable structure so that the movement of the sensing element is facilitated by deformation of the deformable structure, the oscillator frequency being sensitive to both first and second capacitive couplings.

2. The apparatus of claim 1 , the sensing element being supported by the deformable structure, the deformable structure being attached an edge of a closure.

3. The apparatus of claim 2, wherein the closure is a door or gate.

4. The apparatus of claim 1, wherein the signal processing circuit is operable to delect a change in the oscillator frequency, and provide a signal output if the change is greater than a predetermined value.

5. The apparatus of claim 2, wherein the closure is an automatic door, motion of the automatic door being modifiable by the signal output from the signal processing circuit.

6. The apparatus of claim 2, wherein the closure is an automatic garage door having an external side exposed to an outdoor environment, the apparatus further including a water divcrter operable to divert water flow from the external side of the automatic garage door away from the sensing element.

7. The apparatus of claim 6, wherein the deformable structure includes the water diverter.