WO2008052229A2 - Sensor structure - Google Patents
Sensor structure Download PDFInfo
- Publication number
- WO2008052229A2 WO2008052229A2 PCT/ZA2007/000072 ZA2007000072W WO2008052229A2 WO 2008052229 A2 WO2008052229 A2 WO 2008052229A2 ZA 2007000072 W ZA2007000072 W ZA 2007000072W WO 2008052229 A2 WO2008052229 A2 WO 2008052229A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sensor structure
- capacitive
- conductive
- touch
- user
- Prior art date
Links
Classifications
-
- 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
- H03K17/96—Touch switches
- H03K17/962—Capacitive touch switches
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
- G01D5/2405—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by varying dielectric
-
- 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
- G06F3/02—Input arrangements using manually operated switches, e.g. using keyboards or dials
- G06F3/023—Arrangements for converting discrete items of information into a coded form, e.g. arrangements for interpreting keyboard generated codes as alphanumeric codes, operand codes or instruction codes
-
- 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
- G06F3/0354—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
- G06F3/03543—Mice or pucks
-
- 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
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
-
- 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
- G06F3/048—Interaction techniques based on graphical user interfaces [GUI]
- G06F3/0484—Interaction techniques based on graphical user interfaces [GUI] for the control of specific functions or operations, e.g. selecting or manipulating an object, an image or a displayed text element, setting a parameter value or selecting a range
- G06F3/0485—Scrolling or panning
-
- 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
- G06F3/048—Interaction techniques based on graphical user interfaces [GUI]
- G06F3/0487—Interaction techniques based on graphical user interfaces [GUI] using specific features provided by the input device, e.g. functions controlled by the rotation of a mouse with dual sensing arrangements, or of the nature of the input device, e.g. tap gestures based on pressure sensed by a digitiser
- G06F3/0488—Interaction techniques based on graphical user interfaces [GUI] using specific features provided by the input device, e.g. functions controlled by the rotation of a mouse with dual sensing arrangements, or of the nature of the input device, e.g. tap gestures based on pressure sensed by a digitiser using a touch-screen or digitiser, e.g. input of commands through traced gestures
- G06F3/04886—Interaction techniques based on graphical user interfaces [GUI] using specific features provided by the input device, e.g. functions controlled by the rotation of a mouse with dual sensing arrangements, or of the nature of the input device, e.g. tap gestures based on pressure sensed by a digitiser using a touch-screen or digitiser, e.g. input of commands through traced gestures by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus
-
- 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
- H03K17/975—Switches controlled by moving an element forming part of the switch using a capacitive movable element
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
- H03K2217/94036—Multiple detection, i.e. where different switching signals are generated after operation of the user is detected at different time instants at different locations during the actuation movement by two or more sensors of the same or different kinds
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
- H03K2217/96—Touch switches
- H03K2217/9607—Capacitive touch switches
- H03K2217/960755—Constructional details of capacitive touch and proximity switches
Definitions
- This invention relates to a structure for a sensor which can be touch or proximity based and which relies on the use of capacitive sensing techniques.
- a critical design parameter in a good capacitive sensing circuit is a plate which is used to detect variations in capacitance.
- the capacitance of the plate can vary due to coupling via a conductive contact or via any material that acts as a dielectric medium. Different materials have different capacitive coupling efficiencies.
- An electronic circuit is connected to the plate to monitor its operation.
- the connection of the circuit to the plate can be problematic and it would be advantageous if assembly of the plate and circuit could be done without the use of screws or other techniques, such as for example soldering, which result in permanent or semi-permanent conductive contacts.
- the plate may be part of an outer surface of a product and the electronic circuit may be located under cover, in a housing. A connection between the plate and the circuit may therefore present practical difficulties.
- a conductive plate is located on one side of a sheet of glass then, when the other side of the glass is touched, the good capacitive coupling characteristic of the glass causes a significant change in capacitance sensed via the plate.
- the change in capacitance is however dependent on the force which is exerted by the touch action. Also, a small area of touch (resulting, say, from a small finger contacting the glass) does not cause the same result as a large area of touch (resulting, say, from a large finger contacting the glass). Another factor is that it is possible to obtain different results when different areas of the glass plate are touched, even with similar touch actions.
- the invention aims to provide a capacitor-based sensor structure which at least partly addresses the aforementioned factors.
- the invention provides a sensor structure with a first member as part of a sense plate that is electrically conductive but insulated from its surroundings.
- the sensor structure may include a second member which is made from electrically non-conductive material and which has a first surface with at least one region which is electrically conductive.
- the second member can be made from any suitable material such as glass or a plasties material. Glass, in particular, has good capacitive coupling characteristics.
- the second member may be of any suitable shape and size and in one example of the invention the first member is a flat sheet.
- the first surface may be treated in any appropriate way so that it is electrically conductive in the at least one region.
- the at least one electrically conductive region may be formed by applying an electrical layer or coating using any suitable technique, e.g. an etching or deposition technique which deposits an electrically conductive coating on the first surface.
- the second member may have a second non-electrically conductive surface which is spaced from the at least one region.
- At least one insulated conductor e.g. the first member, may be engaged with the second surface or may at least be positioned adjacent the second surface.
- the insulated conductor may be of any appropriate form and for example may comprise an insulated wire or other insulated conductor (e.g. painted metal bracket), a flexible printed circuit board or the like which is capacitively coupled to the at least one conductive region on the first surface.
- the insulated conductor need not be permanently attached to the first member and thus the tasks of assembling and disassembling the sensor structure are facilitated.
- a wire from an electronic circuit, is electrically connected to the surface of a plate structure. Usually this is done in a permanent manner through the use of solder or a loose contact structure such as a spring is used to bias the wire into electrical contact with the plate surface. In the former instance (the fixed connection) the assembly and installation operations are inhibited while, in the latter case, oxidation or variations in the resistance of the contact between the plate and the wire can result in unacceptable changes in the sensor capacitance.
- the insulated conductor can be in the form of a metal plate or frame which can be painted or covered with an insulating material to obtain a double insulating effect.
- a multi-channel capacitive sensing structure is provided by forming the first surface with two or more electrically conductive regions which are separated from one another by at least one non-conductive border or boundary.
- This form of the invention facilitates the implementation of a matrix configuration in that, for each electrically conductive region on the first surface, two or more insulated conductors (depending on the matrix structure required) can be engaged with the second surface directly spaced from the corresponding region on the first surface at least by the material from which the first member is made.
- the sensor structure has two or more regions of the kind referred to then, in a proximity sensing application, it is desirable for maximum capacitance variations to be achieved in response to the presence, say, of a user's hand.
- cross coupling between adjacent regions on the first surface should be reduced. This can be done by introducing a ground plane between adjacent regions and by connecting the ground plane via a suitable resistance to earth. For maximum reduction in touch cross coupling the resistance should be low (of the order of 0 ohms). However for a proximity application the ground plane can be connected to earth via a relative high resistance, say 1 k ohm.
- the cover material may be insulating although in certair i applications it may be conductive with a relative high resistance.
- Another possibility is to make use of a component which has good capacitive coupling characteristics and which is movable by a user into cont act with at least part of a conductive region on the first surface of the first member. In the absence of sufficient force the component is separated from the conductive ⁇ 3gion by an air gap.
- Audible ' feedback can be generated by allowing a lever or other mechanism to generate a click or similar sound when the component contacts the conductive region.
- an active driven shield may be advantageous for preventing unwanted touch activations.
- a headlight i.e. a flashlight to be mounted on a user's head such as a flashlight of the type sold under the name Princeton Tec Aurora
- An active driven shield can then be employed to make the headlamp less sensitive to proximity/touch detection. This will enable the user to operate easily, i.e. to give commands to the headlamp by touching the strap on the side of the head, even with a glove.
- the user will still be able to adjust the headlamp angle by touching the product body. This will require that the body of the product is well shielded by the active driven shield.
- the concept of using an active driven shield to shield a noise-sensitive conductor is well known in the art.
- the headlamp is put into a specific mode that will allow proximity-based operations through activation of an input device e.g. a switch in the form of a push button.
- an input device e.g. a switch in the form of a push button.
- the headlamp can show its status visibly, or otherwise, to the user without consuming too much power.
- any further operations of the input device e.g. a normal push button switch of the headlamp, will cause an exit of the mode in which proximity activation and mode selection are allowed.
- the user In a headlight application of the kind referred to it may be required that the user must specifically enter a specific mode in order to activate the load (i.e. the light source) by using a capacitive sensing type switch. For example it may be required to press a push button switch a number of times or for a predetermined period of time that is longer than the time a user would normally take to activate such a product.
- any further operation of the push button after a predefined period of push button switch inactivity, may then deactivate the capacitive sensing operational mode.
- Figures 1 and 2 are views of first and second sides of a multi-channel capacitive sensing structure according to one form of the invention
- Figures 3(a) and 3(b) illustrate a second side of sensing structure with a matrix configuration
- Figure 4 shows a first side of a multi-channel capacitive sensing structure which includes a ground plane
- Figures 5 and 6 are side views in cross section of a sensing structure in standby and operative modes respectively which is responsive only to the application of a minimum force;
- Figures 7 and 8 are side views in cross section of different sensing structures according to the invention;
- Figures 9(a) and 9(b) show the use of a compressible material to assist with registering a "touch" condition.
- Figures 10 to 12 show a computer mouse with a capacitive sensing structure replacing a rotary wheel
- Figures 13(a) and 13(b) show a proximity capacitive sensing application to activate a flow of water when required.
- Figure 1 of the accompanying drawings illustrates a sensor structure 8 which includes a first member 10 which is made from an electrically insulating material.
- the first member has a square or rectangular configuration outline (this is purely by way of example) and a conductive coating is applied to a first side 12 to form four distinct regions 14, 16, 18 and 20 respectively which are separated from each other by an insulating strip 22 which, in this configuration, is cross-shaped.
- the first member can be made from a plastics material, glass or the like.
- the conductive regions can be formed by any suitable conductive coating, for example by making use of deposition techniques, painting techniques or the like.
- Figure 2 illustrates an opposed second side 24 of the member 12. Perimeters of the strip 22 (on the first side 12) are indicated by dotted lines 26.
- Four insulated wires 28, 30, 32 and 34 are engaged with respective areas 36, 38, 40 and 42 on the non-conducting second side 24, notionally defined by the strip 22, at locations which are more or less centrally positioned and directly opposing the respective regions 14 to 20.
- the insulated wires can be held in position using any suitable technique which dispenses with the use of solder or other permanent or semi-permanent attachment procedures. It is to be noted that the wires are separated from the conductive regions firstly by the insulating material from which the member 12 is made and, secondly, by the insulation on each wire.
- the wires lead to a suitable sensing or control circuit, not shown. This aspect is however known in the art and for this reason is not further described herein.
- Inputs to the sensing circuit can be insulated and positioned such that the sensing circuit couples, according to requirement, with specific conductive regions 14 to 20 only.
- FIGs 3(a) and 3(b) illustrate the second side 24 of a sensing structure 44 which has a first side substantially the same as what is shown in Figure 1.
- Each area 36 to 42 on the second side has two insulated conductors respectively, engaged with it.
- Insulated conductors 46 and 48 extend from the left of the layout to the areas 38 and 36, and 42 and 40, respectively while insulated conductors 50 and 52 extend from an upper end of the layout to the areas 38 and 42, and 36 and 40, respectively. This arrangement can be extended to increase the size of the matrix according to requirement.
- a similar effect can be obtained by using a piece of material, for example in the form of a dome, made from a non-electrically conductive material e.g. a suitable plastic.
- An insulated wire is conductively attached to a conducting layer on an inner side of the dome which then forms the plate.
- the conductive wire is positioned to achieve a good capacitive coupling to a conductive object such as a metal film or plate on an outer side of the dome.
- a touch to a metallic or conductive surface yields a better result in terms of capacitive sensing than merely touching a non-conductive material.
- a soft touch and a hard touch are seen to be more similar in outcomes. This may not always be desirable but in some applications it is advantageous to offer a sure trigger for any touch (soft or hard) which may occur.
- Figure 4 shows a multi-channel capacitive sensing structure 60 wherein conductive regions 62 and 64 on a first side 66 of the structure are separated by a non-conductive area 68 and by a ground plane 70 which is connected to earth through a resistor 72.
- An opposing second side (not shown) of the structure 60 has electrically insulated conductors (28, 30) of the type shown in Figure 2 fixed to it in a way that results in a capacitive coupling between the members 62 and 64 and the wires 28 and 30. "
- a touch on the first side is capacitively coupled to the respective insulated conductor.
- a touch by a finger may be geometrically central in the region 62, say, there could be a degree of capacitive cross-coupling to the region 64. If however the ground plane is grounded with the resistor 72 at a low value (say 0 ohms) then the capacitive cross-coupling is dramatically reduced.
- the ground plane 70 does have an effect on the sensitivity of the capacitive sensing circuit. This is not a problem and in fact is advantageous when dealing with a physical touch situation. If an objective of the circuit is to detect proximity, though, then the use of the ground plane can be detrimental. In the latter case (for proximity sensing) the resistor 72 should have a larger value, say 1 k ohm.
- FIG. 5 illustrates a structure 76, in a stand-by (non-switching) mode in which capacitive sensing plates (conductive regions) 78 and 80 on an insulating member 82 are covered with sheet material 84 which has a dielectric constant (capacitive coupling factor) which is higher than that of air. Air gaps 86 and 88 are formed between the cover and each respective region 78 and 80.
- Figure 7 is a cross sectional view of a structure 90 formed from a first insulating member 92 with tracks on a printed circuit board defining conductive regions 94 and 96.
- a cover material 98 overlies the regions.
- the cover material may be conductive although with a relatively high resistance. It may also be advantageous to form a ground plane 100 between the regions 94 and 96.
- Figure 8 shows a push button type structure 102 in which a button component 104, located in a suitable recess 106 in a compressible or flexible cover material 108, is positioned directly above a conducting region 110 in a non- conductive first member 112.
- An air gap 114 is formed between opposing surfaces of the button 104 and the region 110.
- the button component is made from a material with good capacitive coupling characteristics. The button component is pushed by a user, against a resilient force generated by the cover 108, until the button reduces the size of the intervening air gap 114 to zero and the button makes contact with the region 110.
- the button component at this stage couples decisively with the region 110 and a touch is recognised.
- the movement of the compressible cover, or the button component can be linked to a mechanism which generates an audible sound to indicate to a user that switching action is taken place.
- compressible material 120 is used to cover sense plates (C x i ... C xn ) (122).
- This material has a low capacitive coupling factor.
- a touch on the surface or on a layer of a separate material 124 that is on top of the material
- a proximity event may however be registered and may lead to a response.
- top outer layer 124 constructed to provide a tactile "click" when enough pressure is exerted on it.
- a rotary wheel of the kind which is presently found in a mouse is replaced with a structure 130 using capacitive sense technology that does not require rotary (e.g. wheel) movement ( Figure 10).
- This structure 130 can be similar in outline to the wheel which is currently used, and can follow the profile of the mouse, essentially creating a flat surface upon which a user sweeps a finger in a forward direction or a backward direction.
- the structure 130 is shaped with a raised surface 131 which has a hollow 132 (Figure 11 ) or a hollow 132A (Figure 12(a) - side view, Figure 12(b) - end view, and Figure 12 (c) - plan view, respectively), on an upper side 133 of the mouse.
- This has a natural feel to a user who no longer rotates a wheel but rather sweeps a fingertip in a specified direction.
- This structure can be designed for movement along or across a single axis, or a dual axis device (e.g. like a cross), or a multiple direction device (i.e. responsive to movement in three or more directions) (e.g. the inside of a hemisphere).
- the single axis structure can also be adapted to achieve three further "click" button positions. If pressure (more than is required in a typical sweep movement) is applied backwards in a direction A (see Figure 11 ) a switch is triggered. Similarly, a switch is triggered if pressure is applied in an opposing direction B.
- a further button activation can be achieved when pressure is applied straight down in a direction C. This corresponds to a push on a wheel as found on current rotary wheel mouse implementations.
- the backward sweep movement at the same speed nearer to a forward peripheral part 131 A or a backward peripheral part 131 B is translated to a different scroll rate using a different conversion factor.
- a user moving a fingertip over a touch sensor around a central part at 2 cm per second can effect a scroll rate of, say, 10 lines per second.
- the same speed of fingertip movement close to a peripheral part of the touch sensor can result in a scroll rate of, say, 20 lines per second.
- the forward peripheral part 131 A may be associated with a conversion factor leading to a slower rate of translation and for the backward peripheral part 131 B to be associated with a conversion factor leading to a faster rate of translation.
- the rate of translation associated with the centre can lie between the faster and the slower rates.
- the conversion factor for the various parts of the touch sensor can be reversed for sweep movements in different directions, with the factor related to the centre part of the touch sensor being substantially constant. [0059]
- movement of a cursor on a screen is related (in this example) to the position on a structure upon which a user's finger operates, and on the direction of such sweep movement.
- the sense plate on the mouse is constructed from a single electrically conductive region.
- the region must have some resistive properties which are preferably uniform over its surface. In some embodiments though the surface could have non-linear resistive properties to produce desired effects.
- movement of the mouse is sensed using capacitive sensing plates to reference the location of the mouse against some fixed reference points on a surface upon which the mouse is moved, or a tap or double tap on the touch sensor strip described may latch a movement on the screen with the position of where the tap occurred on the strip conveying information with regards to speed.
- the tap(s) may also be used for other function selection as per a electromechanical switch. For example a sweep of the finger may set a rate of movement and a tap within a predefined period thereafter may latch the movement until a further tap is performed later. It may be advantageous to have further taps at various positions of the touch sensor strip increasing or decreasing the rate of movement in predefined steps or halting the movement.
- the scrolling may be paused with a touch on the strip, to be continued upon removal of the touch condition.
- a double tap or a tap on a certain position thereafter may not only stop the scrolling but may also reset the screen to the position that was on the screen during the pause.
- a further embodiment of this technology lies in the field of urinal flushers where most sensing is currently implemented using infrared (IR) technology.
- IR infrared
- apparatus which uses any of the capacitive sensing mechanisms and sensor plates described herein can be used, embedded in or behind a suitable device section, at a suitable location, which fronts a urinal as is shown from one side in Figure 13(a), and in plan in Figure 13(b).
- a control unit of a water dispenser or flusher of the ' urinal can activate water-flow based on predetermined criteria or on a pattern of proximity detection signals.
- the urinal has a body with a bowl 137 in which is located a drain 139.
- proximity user presence
- the urinal has a body with a bowl 137 in which is located a drain 139.
- proximity For example, proximity (user presence) must be present for a minimum period of time and must then turn to "no proximity" detected (user absence) for another minimum period of time to cause flushing.
- Power for an electronic circuit required to operate can be derived from long life batteries. It is also possible, though, to generate energy from water flow in the urinal to charge some energy storage facilities.
- the power generating device can be hidden from the view of a user.
- an antenna C x
- the antenna can be positioned behind or on a front lip of the bowl of the urinal, and conveniently can be at the nearest point to which a user is normally positioned.
- the antenna can be fully, or doubly, insulated to eliminate any chance of electrical shock.
- the antenna is connected to the electronic circuitry conveniently located out of sight.
- the antenna could be in the form of a plate that the user must stand on to use the urinal. This plate may be in the form of glass or other material with a conductive layer, or may be conductive wiring that is positioned conveniently between tiles on the floor.
- the sensing element e.g. the insulated wire or sense plate
- the sensing element may in some embodiments be connected to the capacitive sensing electronics with a conductor that is shielded from the outside world by means of an active driven shield. This will help to prevent unwanted proximity or touch event triggers from occurring due to capacitive coupling taking place with areas other than the sense element.
- the active driven shield also helps to improve the sensitivity of the capacitive sensor, particularly when operating from a non-mains power supply and without an earth.
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Human Computer Interaction (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Electronic Switches (AREA)
- Push-Button Switches (AREA)
Abstract
A multi-channel capacitive sensing structure which includes a member on a first side has a first surface with two or more electrically conductive regions separated from one another by a non-conductive boundary, and two or more insulated conductors arranged on a second non-electhcally conductive surface, on a second side of the member opposing the first side, spaced from each conductive region by the member and capacitively coupled thereto.
Description
SENSOR STRUCTURE
BACKGROUND OF THE INVENTION
[001] This invention relates to a structure for a sensor which can be touch or proximity based and which relies on the use of capacitive sensing techniques.
[002] A critical design parameter in a good capacitive sensing circuit is a plate which is used to detect variations in capacitance. The capacitance of the plate can vary due to coupling via a conductive contact or via any material that acts as a dielectric medium. Different materials have different capacitive coupling efficiencies.
[003] In the presence of a main supply, for example if a live or neutral conductor is to be switched, it is desirable to insulate the plate or any other surface that can be touched by a user from the main supply. This precaution should also be taken to safeguard against adverse effects arising from component malfunction. There are however significant advantages in certain touch applications if a surface which is to be touched is conductive.
[004] An electronic circuit is connected to the plate to monitor its operation. The connection of the circuit to the plate can be problematic and it would be advantageous if assembly of the plate and circuit could be done without the use of screws or other techniques, such as for example soldering, which result in permanent or semi-permanent conductive contacts. For example, the plate may be part of an outer surface of a product and the electronic circuit may be located under cover, in a housing. A connection between the plate and the circuit may therefore present practical difficulties.
[005] If a conductive plate is located on one side of a sheet of glass then, when the other side of the glass is touched, the good capacitive coupling characteristic of the glass causes a significant change in capacitance sensed via the plate. The change in capacitance is however dependent on the force which is exerted by the touch action. Also, a small area of touch (resulting, say, from a small finger contacting the glass) does not cause the same result as a large area of touch (resulting, say, from a large finger contacting the glass). Another factor is that it is possible to obtain different results when different areas of the glass plate are touched, even with similar touch actions.
[006] Applications using infra red (IR) technology, instead of capacitive coupling, to sense human proximity are quite common. These have several requirements that may not always be desirable such as high energy usage, location required, cost and cost of installation.
[007] The invention aims to provide a capacitor-based sensor structure which at least partly addresses the aforementioned factors.
SUMMARY OF INVENTION
[008] In a preferred embodiment the invention provides a sensor structure with a first member as part of a sense plate that is electrically conductive but insulated from its surroundings.
[009] The sensor structure may include a second member which is made from electrically non-conductive material and which has a first surface with at least one region which is electrically conductive.
[0010] The second member can be made from any suitable material such as glass or a plasties material. Glass, in particular, has good capacitive coupling characteristics.
[0011] The second member may be of any suitable shape and size and in one example of the invention the first member is a flat sheet.
[0012] The first surface may be treated in any appropriate way so that it is electrically conductive in the at least one region.
[0013] The at least one electrically conductive region may be formed by applying an electrical layer or coating using any suitable technique, e.g. an etching or deposition technique which deposits an electrically conductive coating on the first surface.
[0014] The second member may have a second non-electrically conductive surface which is spaced from the at least one region. At least one insulated conductor, e.g. the first member, may be engaged with the second surface or may at least be positioned adjacent the second surface. The insulated conductor may be of any appropriate form and for example may comprise an insulated wire or other insulated conductor (e.g. painted metal bracket), a flexible printed circuit board or the like which is capacitively coupled to the at least one conductive region on the first surface.
[0015] The insulated conductor need not be permanently attached to the first member and thus the tasks of assembling and disassembling the sensor structure are facilitated.
[0016] It is to be borne in mind that in a typical capacitive sensing circuit a wire, from an electronic circuit, is electrically connected to the surface of a plate structure. Usually this is done in a permanent manner through the use of solder or a loose contact structure such as a spring is used to bias the wire into electrical contact with the plate surface. In the former instance (the fixed connection) the assembly and installation operations are inhibited while, in the latter case, oxidation or variations in the resistance of the contact between the plate and the wire can result in unacceptable changes in the sensor capacitance. These aspects are overcome by the use of the insulated conductor which is engaged with the second surface.
[0017] With the method of the invention a double insulating effect is achieved in that firstly, insulation is provided by the insulating conductor and, secondly, insulation is provided by the insulating effect of the first member.
[0018] The insulated conductor can be in the form of a metal plate or frame which can be painted or covered with an insulating material to obtain a double insulating effect.
[0019] In a variation of the invention a multi-channel capacitive sensing structure is provided by forming the first surface with two or more electrically conductive regions which are separated from one another by at least one non-conductive border or boundary. This form of the invention facilitates the implementation of a matrix configuration in that, for each electrically conductive region on the first surface, two or more insulated conductors (depending on the matrix structure required) can be engaged with the second surface directly spaced from the corresponding region on the first surface at least by the material from which the first member is made.
[0020] If the sensor structure has two or more regions of the kind referred to then, in a proximity sensing application, it is desirable for maximum capacitance variations to be achieved in response to the presence, say, of a user's hand. However, if the sensor circuit is to be used in a touch application then cross coupling between adjacent regions on the first surface should be reduced. This can be done by introducing a ground plane between adjacent regions and by connecting the ground plane via a suitable resistance to earth. For maximum reduction in touch cross coupling the resistance should be low (of the order of 0 ohms). However for a proximity application the ground plane can be connected to earth via a relative high resistance, say 1 k ohm.
[0021] In some applications it may be desirable to register c\ touch only when a certain minimum pressure is applied to a sensing surface, for example by a user's finger. This can be achieved by covering the conductive region with an appropriate material which has a dielectric constant better than that of air and with an air gap between the cover material and the at least one region. Altemat ively compression of the cover material may be sufficient to register a touch, without the air gap being necessary.
[0022] The cover material may be insulating although in certair i applications it may be conductive with a relative high resistance.
[0023] Another possibility is to make use of a component which has good capacitive coupling characteristics and which is movable by a user into cont act with at least part of a conductive region on the first surface of the first member. In the absence of sufficient force the component is separated from the conductive π 3gion by an air gap.
[0024] Audible' feedback can be generated by allowing a lever or other mechanism to generate a click or similar sound when the component contacts the conductive region.
[0025] In a further embodiment the use of an active driven shield may be advantageous for preventing unwanted touch activations. For example in the use of capacitive sensing switch technology in a headlight (i.e. a flashlight to be mounted on a user's head such as a flashlight of the type sold under the name Princeton Tec Aurora) it may be desirable to locate a sense plate in a fastener eg. a strap on a side of the user's head. An active driven shield can then be employed to make the headlamp less sensitive to proximity/touch detection. This will enable the user to operate easily, i.e. to give commands to the headlamp by touching the strap on the side of the head, even with a glove. The user will still be able to adjust the headlamp angle by touching the product body. This will require that the body of the product is well shielded by the active driven shield. The concept of using an active driven shield to shield a noise-sensitive conductor is well known in the art.
[0026] In a specific embodiment the headlamp is put into a specific mode that will allow proximity-based operations through activation of an input device e.g. a switch in the form of a push button. In this mode, the headlamp can show its status visibly, or otherwise, to the user without consuming too much power.
[0027] In another embodiment any further operations of the input device, e.g. a normal push button switch of the headlamp, will cause an exit of the mode in which proximity activation and mode selection are allowed.
[0028] In another embodiment it is advantageous to activate the driven shield only once a proximity event has been detected. This may assist in more sensitivity in terms of proximity detection, by directing physical touch detection towards a specified area only. In a headlight application of the kind referred to it may be required that the user must specifically enter a specific mode in order to activate the load (i.e. the light source) by using a capacitive sensing type switch. For example it may be required to press a push button switch a number of times or for a predetermined period of time that is longer than the time a user would normally take to activate such a product.
[0029] As is described in US 6249089 and EP 1120018 any further operation of the push button, after a predefined period of push button switch inactivity, may then deactivate the capacitive sensing operational mode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The invention is further described by way of examples with reference to the accompanying drawings in which:
Figures 1 and 2 are views of first and second sides of a multi-channel capacitive sensing structure according to one form of the invention;
Figures 3(a) and 3(b) illustrate a second side of sensing structure with a matrix configuration;
Figure 4 shows a first side of a multi-channel capacitive sensing structure which includes a ground plane;
Figures 5 and 6 are side views in cross section of a sensing structure in standby and operative modes respectively which is responsive only to the application of a minimum force;
Figures 7 and 8 are side views in cross section of different sensing structures according to the invention;
Figures 9(a) and 9(b) show the use of a compressible material to assist with registering a "touch" condition.
Figures 10 to 12 show a computer mouse with a capacitive sensing structure replacing a rotary wheel; and
Figures 13(a) and 13(b) show a proximity capacitive sensing application to activate a flow of water when required.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0031] Figure 1 of the accompanying drawings illustrates a sensor structure 8 which includes a first member 10 which is made from an electrically insulating material. The first member has a square or rectangular configuration outline (this is purely by way of example) and a conductive coating is applied to a first side 12 to form four distinct regions 14, 16, 18 and 20 respectively which are separated from each other by an insulating strip 22 which, in this configuration, is cross-shaped.
[0032] The first member can be made from a plastics material, glass or the like. The conductive regions can be formed by any suitable conductive coating, for example by making use of deposition techniques, painting techniques or the like.
[0033] Figure 2 illustrates an opposed second side 24 of the member 12. Perimeters of the strip 22 (on the first side 12) are indicated by dotted lines 26. Four insulated wires 28, 30, 32 and 34 are engaged with respective areas 36, 38, 40 and 42 on the non-conducting second side 24, notionally defined by the strip 22, at locations which are more or less centrally positioned and directly opposing the
respective regions 14 to 20. The insulated wires can be held in position using any suitable technique which dispenses with the use of solder or other permanent or semi-permanent attachment procedures. It is to be noted that the wires are separated from the conductive regions firstly by the insulating material from which the member 12 is made and, secondly, by the insulation on each wire.
[0034] The wires lead to a suitable sensing or control circuit, not shown. This aspect is however known in the art and for this reason is not further described herein. Inputs to the sensing circuit can be insulated and positioned such that the sensing circuit couples, according to requirement, with specific conductive regions 14 to 20 only.
[0035] Due to the geometrical layout of the structure cross-coupling effects between adjacent regions are fairly low.
[0036] The configuration shown in Figures 1 and 2 lends itself readily to the creation of a matrix structure of the kind shown, by way of example only, in Figures 3(a) and 3(b).
[0037] Figures 3(a) and 3(b) illustrate the second side 24 of a sensing structure 44 which has a first side substantially the same as what is shown in Figure 1. Each area 36 to 42 on the second side has two insulated conductors respectively, engaged with it. Insulated conductors 46 and 48 extend from the left of the layout to the areas 38 and 36, and 42 and 40, respectively while insulated conductors 50 and 52 extend from an upper end of the layout to the areas 38 and 42, and 36 and 40, respectively. This arrangement can be extended to increase the size of the matrix according to requirement.
[0038] Positive simultaneous signals on the wires 46 and 50, or on the wires 46 and 52, or on the wires 48 and 50, or on the wires 48 and 52 indicate, respectively, that the corresponding opposed region 14, 16, 18 or 20 has been touched by a user. Clearly this technique provides good discrimination between a touch and a no-touch situation.
[0039] A similar effect can be obtained by using a piece of material, for example in the form of a dome, made from a non-electrically conductive material e.g. a suitable plastic. An insulated wire is conductively attached to a conducting layer on an inner side of the dome which then forms the plate. Alternatively the conductive wire is positioned to achieve a good capacitive coupling to a conductive object such as a metal film or plate on an outer side of the dome.
[0040] A touch to a metallic or conductive surface yields a better result in terms of capacitive sensing than merely touching a non-conductive material. For example a soft touch and a hard touch are seen to be more similar in outcomes. This may not always be desirable but in some applications it is advantageous to offer a sure trigger for any touch (soft or hard) which may occur.
[0041] Figure 4 shows a multi-channel capacitive sensing structure 60 wherein conductive regions 62 and 64 on a first side 66 of the structure are separated by a non-conductive area 68 and by a ground plane 70 which is connected to earth through a resistor 72.
[0042] An opposing second side (not shown) of the structure 60 has electrically insulated conductors (28, 30) of the type shown in Figure 2 fixed to it in a way that results in a capacitive coupling between the members 62 and 64 and the wires 28
and 30. " Thus a touch on the first side is capacitively coupled to the respective insulated conductor. Even though a touch by a finger may be geometrically central in the region 62, say, there could be a degree of capacitive cross-coupling to the region 64. If however the ground plane is grounded with the resistor 72 at a low value (say 0 ohms) then the capacitive cross-coupling is dramatically reduced.
[0043] The ground plane 70 does have an effect on the sensitivity of the capacitive sensing circuit. This is not a problem and in fact is advantageous when dealing with a physical touch situation. If an objective of the circuit is to detect proximity, though, then the use of the ground plane can be detrimental. In the latter case (for proximity sensing) the resistor 72 should have a larger value, say 1 k ohm. This could present a compromise in terms of the sensitivity required for proximity detection and the separation of the touch detection situations between the sensing regions 62 and 64; or the resistor 72 could be large (several k ohms) until a proximity event is sensed upon which the resistance of the resistor is switched to a much lower value to help in sensing for touch, particularly if the separation of touch events on different regions is more important.
[0044] From the aforegoing it is apparent that it falls within the scope of the invention to adapt the sensing structure through the appropriate use of a ground plane specifically to yield better results, according to requirement, for proximity sensing or for touch sensing. In general, better stability and reduction of noise per channel can be obtained, when measuring a specific channel, if other channels are grounded. This step does however reduce sensitivity when proximity sensing is required. Thus when reliable proximity sensing is required it is preferred to leave the channels floating and for the ground planes, if any, to be connected to earth through a higher value resistance, or not at all.
[0045] In some situations it is desirable to register or record a touch only when a certain minimum force has been applied by a user. A tactile feel or feedback may be desirable as well. Because of the substantial differences in the extent of capacitive coupling of materials such as glass, Perspex, nylon, plastic and air it is possible to create a force-dependent touch sensor using capacitive-sensing technology. Figure 5 illustrates a structure 76, in a stand-by (non-switching) mode in which capacitive sensing plates (conductive regions) 78 and 80 on an insulating member 82 are covered with sheet material 84 which has a dielectric constant (capacitive coupling factor) which is higher than that of air. Air gaps 86 and 88 are formed between the cover and each respective region 78 and 80. As is shown in Figure 6, to place the structure in an operative mode, a user's hand must depress the cover directly above a respective region so that the cover is brought into contact with the region or, at least, is brought relatively closer to the region. Only when this occurs will a touch be registered.
[0046] Figure 7 is a cross sectional view of a structure 90 formed from a first insulating member 92 with tracks on a printed circuit board defining conductive regions 94 and 96. A cover material 98 overlies the regions. The cover material may be conductive although with a relatively high resistance. It may also be advantageous to form a ground plane 100 between the regions 94 and 96.
[0047] Figure 8 shows a push button type structure 102 in which a button component 104, located in a suitable recess 106 in a compressible or flexible cover material 108, is positioned directly above a conducting region 110 in a non- conductive first member 112. An air gap 114 is formed between opposing surfaces of the button 104 and the region 110. The button component is made from a material with good capacitive coupling characteristics. The button component is pushed by a
user, against a resilient force generated by the cover 108, until the button reduces the size of the intervening air gap 114 to zero and the button makes contact with the region 110. The button component at this stage couples decisively with the region 110 and a touch is recognised. The movement of the compressible cover, or the button component, can be linked to a mechanism which generates an audible sound to indicate to a user that switching action is taken place.
[0048] In a further embodiment (see Figure 9(a) which shows a no-touch condition, and Figure 9(b) which shows a load condition) compressible material 120 is used to cover sense plates (Cxi ... Cxn) (122). This material has a low capacitive coupling factor. When uncompressed a touch on the surface (or on a layer of a separate material 124 that is on top of the material) does not lead to registration of a "touch". A proximity event may however be registered and may lead to a response. When a user exerts pressure (126) and the material is compressed beyond a certain minimum thickness (128) the capacitive coupling between the object and the sense plate arising from the pressure 126 (e.g. finger pressure) improves to such an extent, because of the higher material density and/or the smaller geometrical separation, that a "touch" condition is registered (Figure 9(b)). This structure prevents the detection of a "touch" when the user merely rests a finger on a surface (no or little compression) that is designed to detect a "touch".
[0049] It is also possible to have the top outer layer 124 constructed to provide a tactile "click" when enough pressure is exerted on it.
[0050] In a further embodiment, specifically related to the use of capacitive sense technology in computer pointing applications, such as for example a computer mouse, a rotary wheel of the kind which is presently found in a mouse is replaced
with a structure 130 using capacitive sense technology that does not require rotary (e.g. wheel) movement (Figure 10).
[0051] This structure 130 can be similar in outline to the wheel which is currently used, and can follow the profile of the mouse, essentially creating a flat surface upon which a user sweeps a finger in a forward direction or a backward direction.
[0052] In a preferred embodiment the structure 130 is shaped with a raised surface 131 which has a hollow 132 (Figure 11 ) or a hollow 132A (Figure 12(a) - side view, Figure 12(b) - end view, and Figure 12 (c) - plan view, respectively), on an upper side 133 of the mouse.
[0053] This has a natural feel to a user who no longer rotates a wheel but rather sweeps a fingertip in a specified direction. This structure can be designed for movement along or across a single axis, or a dual axis device (e.g. like a cross), or a multiple direction device (i.e. responsive to movement in three or more directions) (e.g. the inside of a hemisphere).
[0054] The single axis structure can also be adapted to achieve three further "click" button positions. If pressure (more than is required in a typical sweep movement) is applied backwards in a direction A (see Figure 11 ) a switch is triggered. Similarly, a switch is triggered if pressure is applied in an opposing direction B.
[0055] A further button activation can be achieved when pressure is applied straight down in a direction C. This corresponds to a push on a wheel as found on current rotary wheel mouse implementations.
[0056] IrI a further variation, there can be a non-linear correlation between the sweep movement of a user's fingertip over a touch sensor, to the movement of a cursor on a screen or to a sensor of a document on a screen which is produced by an output signal of the sense structure. For example, the sweep movement of the user's fingertip over an inner (centre) part of the touch sensor is non-linearly translated into movement of the cursor or to a scroll rate of the scrolling action, using a certain conversion factor. Referring to Figure 11 the backward sweep movement at the same speed nearer to a forward peripheral part 131 A or a backward peripheral part 131 B (also for flat or ball shapes) is translated to a different scroll rate using a different conversion factor. For example, a user moving a fingertip over a touch sensor around a central part at 2 cm per second can effect a scroll rate of, say, 10 lines per second. The same speed of fingertip movement close to a peripheral part of the touch sensor can result in a scroll rate of, say, 20 lines per second.
[0057] As such the user can decide what speed of fingertip movement is comfortable and choose a corresponding part of the touch sensor necessary to achieve the desired scroll rate.
[0058] It may make sense for the forward peripheral part 131 A to be associated with a conversion factor leading to a slower rate of translation and for the backward peripheral part 131 B to be associated with a conversion factor leading to a faster rate of translation. The rate of translation associated with the centre can lie between the faster and the slower rates. The conversion factor for the various parts of the touch sensor can be reversed for sweep movements in different directions, with the factor related to the centre part of the touch sensor being substantially constant.
[0059] Thus movement of a cursor on a screen is related (in this example) to the position on a structure upon which a user's finger operates, and on the direction of such sweep movement. This process of relating finger movement to cursor movement is more convenient than spinning the wheel of a typical mouse, faster or slower, and requires fewer moving parts to implement. Thus it is anticipated that the process will be more reliable and have longer mtbf (mean time between failures), and be cheaper than existing techniques to implement.
[0060] In a specific construction the sense plate on the mouse is constructed from a single electrically conductive region. The region must have some resistive properties which are preferably uniform over its surface. In some embodiments though the surface could have non-linear resistive properties to produce desired effects.
[0061] By using a single sensing channel connected to one side of the conductive region and with the other side connected to a dummy load (or another sensing channel), the position of touch by an object (e.g. a user's finger) can be determined (see other patent applications by Bruwer). It is then also possible to detect and track movement over the sense plate.
[0062] In other embodiments, movement of the mouse is sensed using capacitive sensing plates to reference the location of the mouse against some fixed reference points on a surface upon which the mouse is moved, or a tap or double tap on the touch sensor strip described may latch a movement on the screen with the position of where the tap occurred on the strip conveying information with regards to speed. The tap(s) may also be used for other function selection as per a electromechanical switch. For example a sweep of the finger may set a rate of movement and a tap within a predefined period thereafter may latch the movement until a further tap is
performed later. It may be advantageous to have further taps at various positions of the touch sensor strip increasing or decreasing the rate of movement in predefined steps or halting the movement. In a specific embodiment where the screen is scrolling at a set rate, the scrolling may be paused with a touch on the strip, to be continued upon removal of the touch condition. A double tap or a tap on a certain position thereafter may not only stop the scrolling but may also reset the screen to the position that was on the screen during the pause.
[0063] A further embodiment of this technology lies in the field of urinal flushers where most sensing is currently implemented using infrared (IR) technology.
[0064] It is common practice for an IR sensor mechanism to be placed above an urinal to trigger flushing in a manner which is dependent on movement, or on the presence, of a user. However capacitive sensing technology can be implemented in a system which is located inconspicuously and which can be installed at a lower price and which uses less power.
[0065] Thus, apparatus which uses any of the capacitive sensing mechanisms and sensor plates described herein can be used, embedded in or behind a suitable device section, at a suitable location, which fronts a urinal as is shown from one side in Figure 13(a), and in plan in Figure 13(b).
[0066] Based on proximity detection using capacitive sensing in areas adjacent regions A, B and C of a urinal 135, a control unit of a water dispenser or flusher of the' urinal can activate water-flow based on predetermined criteria or on a pattern of proximity detection signals. The urinal has a body with a bowl 137 in which is located a drain 139. For example, proximity (user presence) must be present for a minimum
period of time and must then turn to "no proximity" detected (user absence) for another minimum period of time to cause flushing. Power for an electronic circuit required to operate can be derived from long life batteries. It is also possible, though, to generate energy from water flow in the urinal to charge some energy storage facilities.
[0067] The power generating device can be hidden from the view of a user. For example, an antenna (Cx) can be positioned behind or on a front lip of the bowl of the urinal, and conveniently can be at the nearest point to which a user is normally positioned. The antenna can be fully, or doubly, insulated to eliminate any chance of electrical shock. The antenna is connected to the electronic circuitry conveniently located out of sight. The antenna could be in the form of a plate that the user must stand on to use the urinal. This plate may be in the form of glass or other material with a conductive layer, or may be conductive wiring that is positioned conveniently between tiles on the floor.
[0068] In this regard use can be made, as necessary, of any of the techniques described in the specification of South African patent application No. 2006/08894, the content of which is hereby fully incorporated.
[0069] In the various examples of the invention which have been described herein, the sensing element, e.g. the insulated wire or sense plate, may in some embodiments be connected to the capacitive sensing electronics with a conductor that is shielded from the outside world by means of an active driven shield. This will help to prevent unwanted proximity or touch event triggers from occurring due to capacitive coupling taking place with areas other than the sense element.
[0070] The active driven shield also helps to improve the sensitivity of the capacitive sensor, particularly when operating from a non-mains power supply and without an earth.
Claims
1. A capacitive sensor comprising a sensing structure which includes at least one first member which is electrically connected to an electronic capacitive sensing circuit which is electrically insulated from its surrounding and a second member, forming a sense plate, made from an electrically non- conductive material, which has at least a first surface with at least one region which is electrically conductive, and wherein capacitive coupling exists between the first member and the electrically conductive surface of the second member.
2. A sensor structure according to claim 1 wherein the second member is made from glass or a plastics material.
3. A sensor structure according to claim 1 or 2 wherein the at least one conductive surface region is formed by at least one of the following: depositing an electrically conductive coating on the first surface; applying an electrically conductive paint on the first surface.
4. A sensor structure according to claim 1 , 2 or 3 which has a second surface, which is spaced from the at least one conductive region and which is non- electrically conductive, and which is adjacent or physically engaged with the first member.
5. A sensor structure according to claim 4 wherein the insulated first member is selected from an insulated wire, a coated metal bracket and a flexible printed circuit board which is capacitively coupled to the at least one conductive region on the first surface.
6. A sensor structure according to any one of claims 1 to 5 which includes a covering over the at least one conductive region, and wherein the covering is:
(a) a material which has a dielectric constant that is better for capacitive coupling than that of air and an air gap is formed between the covering and the at least one conductive region; or
(b) an insulating material; or
(c) a conductive material with a high resistance.
7. A sensor structure according to any one of claims 1 to 6 which includes a material, covering the sense plate or deposited between a plurality of conducting regions, which is chosen to have lower electrical resistance in order to provide better separation of touch events between conducting regions or to have a higher resistance to improve sensitivity for proximity sensing from all areas.
8. A sensor structure according to any one of claims 1 to 6 which includes a ground plane between a plurality of adjacent conductive regions on the first surface, and a connection of the ground plane to earth.
9. A sensor structure according to claim 8 wherein the connection to earth is a resistive connection and wherein the resistance can be varied to choose between separation of touch between regions or better sensitivity for proximity detection.
10. A capacitive sensor comprising a sense plate which is electrically connected to a electronic sensing circuit with a covering material that has a capacitive coupling factor that is lower than that of glass and better than that of air, the covering material being compressible and being of a nature so that, when compressed by an object touching the cover material with enough force to compress it and the sense plate, the material has a higher density or thinner dimension thereby increasing capacitive coupling to effect the registering of a touch event, whereas a physical touch of a surface of the covering material by the same object without compressing it to some degree, will not register a touch event through the capacitive sensor but only a proximity event.
11. A urinal which comprises a body and a bowl and which is fitted with a capacitive sensing device to trigger flushing of the bowl, wherein the capacitive sensing device includes a sense plate in the form of an insulated conductor or insulated wire or metal strip at a front lip of the bowl and a connector which connects the sense plate to a capacitive sensing electronic circuit, and wherein a part of the connecter is covered with an active driven shield to prevent unwanted proximity event detections due to undesired capacitive coupling with the connector in an area linking the sense plate and the capacitive sensing electronic circuit.
12. A urinal according to claim 11 wherein the active driven shield is also instrumental in creating a better sensitivity due to separation between the sense plate and a non-mains power source, to yield improved stable proximity detection distance.
13. A computer pointer which includes a body and at least one capacitive sensor structure which is positioned on the body so that the sensor structure is accessible by a finger of a user and is responsive to movement of the finger over the sensor structure, as well as to single or multiple finger tap/touch actions, and wherein the sensing of the finger actions on the sensor structure translate to movement or function selection on a computer screen.
14. A computer pointer according to claim 13 wherein the sensor structure is responsive to movement of a finger of a user in one direction, or in multiple directions.
15. A computer pointer according to claim 13 or 14 wherein the sensor structure, in response to pressure in at least a first direction exhibits a first switching action.
16. A computer pointer according to claim 13, 14 or 15 wherein the sensor structure produces an output which has a non-linear correlation with movement of a user's finger over the sensor structure.
17. A computer pointer according to any one of claims 13 to 16 wherein the sensor structure produces an output signal which is dependent on the position of a user's finger on the sensor structure and on the direction of movement of the user's finger over the sensor structure.
18. A computer pointer according to any one of claims 13 to 17 wherein the sensor structure has a sense plate which is constructed from a single conductive region having an electrically resistive characteristic with only a single or two sensing channels required for tracking movement in a single dimension.
19. Use of a sensor structure according to any one of claims 1 to 10 which is positioned so that the sensor structure is responsive to the proximity or absence of a user and produces an output signal which is used to control operation of a water dispenser.
20. A headlamp which has a strap that is positioned on a side of a user's head when the headlamp is in use and which is fitted with a capacitive sensing device and an input device, operable by the user, for activation/deactivation and operating mode selection of the headlamp, wherein the capacitive sensing device includes a sense plate which is located on the strap, and a connector, between the sense plate and a capacitive sensing electronic circuit, which comprises an insulated conductor or insulated wire or metal strip, and wherein a part of the connector is covered with an active driven shield to prevent unwanted proximity event detections due to undesired capacitive coupling with the connector in an area linking the sense plate and the capacitive sensing electronic circuit.
21. A headlamp according to claim 20 wherein the input device is operable to select a proximity activation and deactivation mode.
22. A headlamp according to claim 21 wherein the proximity activation and deactivation mode is one of a plurality of operating modes selectable by operation of the input device.
23. A headlamp according to any one of claims 20 to 22 wherein the input device is a switch.
24. A headlamp according to claim 23 wherein the switch is a push button switch.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA2006/08894 | 2006-10-26 | ||
ZA200608894 | 2006-10-26 | ||
ZA200609995 | 2006-11-13 | ||
ZA2006/9995 | 2006-11-13 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2008052229A2 true WO2008052229A2 (en) | 2008-05-02 |
WO2008052229A3 WO2008052229A3 (en) | 2009-05-28 |
Family
ID=39325506
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/ZA2007/000072 WO2008052229A2 (en) | 2006-10-26 | 2007-10-26 | Sensor structure |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2008052229A2 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2011130755A3 (en) * | 2010-04-14 | 2011-12-08 | Frederick Johannes Bruwer | Pressure dependent capacitive sensing circuit switch construction |
EP2860744A4 (en) * | 2012-06-12 | 2015-06-24 | Fujikura Ltd | Input device |
WO2017190900A1 (en) * | 2016-05-04 | 2017-11-09 | Preh Gmbh | Input device with function triggering or control which takes place on the basis of a capacitively measured actuation force and adaptation by means of capacitive contact detection |
EP3116010A4 (en) * | 2014-03-07 | 2017-12-06 | Shin-Etsu Polymer Co. Ltd. | Switch apparatus |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2080536A (en) * | 1980-07-10 | 1982-02-03 | Faff Peter | Touch Switch Device |
US6249130B1 (en) * | 1998-12-21 | 2001-06-19 | Agrichem, Inc. | Shielded flat-plate proximity/dielectric properties sensor |
US20030102875A1 (en) * | 2001-11-22 | 2003-06-05 | Toshimitsu Fujiwara | Input device |
-
2007
- 2007-10-26 WO PCT/ZA2007/000072 patent/WO2008052229A2/en active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2080536A (en) * | 1980-07-10 | 1982-02-03 | Faff Peter | Touch Switch Device |
US6249130B1 (en) * | 1998-12-21 | 2001-06-19 | Agrichem, Inc. | Shielded flat-plate proximity/dielectric properties sensor |
US20030102875A1 (en) * | 2001-11-22 | 2003-06-05 | Toshimitsu Fujiwara | Input device |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2011130755A3 (en) * | 2010-04-14 | 2011-12-08 | Frederick Johannes Bruwer | Pressure dependent capacitive sensing circuit switch construction |
EP2846465A3 (en) * | 2010-04-14 | 2015-04-01 | Frederick Johannes Bruwer | Pressure dependent capacitive sensing circuit switch construction |
EP2860744A4 (en) * | 2012-06-12 | 2015-06-24 | Fujikura Ltd | Input device |
US9882561B2 (en) | 2012-06-12 | 2018-01-30 | Fujikura Ltd. | Input device |
EP3116010A4 (en) * | 2014-03-07 | 2017-12-06 | Shin-Etsu Polymer Co. Ltd. | Switch apparatus |
US9966952B2 (en) | 2014-03-07 | 2018-05-08 | Shin-Etsu Polymer Co., Ltd. | Switch apparatus |
WO2017190900A1 (en) * | 2016-05-04 | 2017-11-09 | Preh Gmbh | Input device with function triggering or control which takes place on the basis of a capacitively measured actuation force and adaptation by means of capacitive contact detection |
CN108432138A (en) * | 2016-05-04 | 2018-08-21 | 普瑞有限公司 | Input unit with the function triggering carried out according to the operating force of measurement by capacitance or control and the adaptation carried out by capacitance touch detection |
US10924111B2 (en) | 2016-05-04 | 2021-02-16 | Preh Gmbh | Input device with function triggering or control which takes place based on capacitively measured actuation force and adaptation by means of capacitive contact detection |
Also Published As
Publication number | Publication date |
---|---|
WO2008052229A3 (en) | 2009-05-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9948297B2 (en) | Pressure dependent capacitive sensing circuit switch construction | |
US7279647B2 (en) | Control panel | |
US20100200309A1 (en) | Two-dimensional position sensor | |
US6184865B1 (en) | Capacitive pointing stick apparatus for symbol manipulation in a graphical user interface | |
EP1695529B1 (en) | Rotator wheel | |
US6587093B1 (en) | Capacitive mouse | |
US20090002199A1 (en) | Piezoelectric sensing as user input means | |
TW202009659A (en) | Clickable knob for touch sensors | |
WO2005073834A3 (en) | Touch screens | |
US10379637B2 (en) | Rotational element enabling touch-like gestures | |
US20060214923A1 (en) | Touchpad having capability of inducing sensation of tactile key | |
US20060232559A1 (en) | Capacitive touchpad with physical key function | |
US8134533B2 (en) | Mouse with integrated keyplate and housing | |
US20140002358A1 (en) | Compact capacitive track pad | |
JP2008198205A (en) | Tilting touch control panel | |
WO2013075345A1 (en) | Touch recognition method and device, space mouse and control method thereof | |
WO2008052229A2 (en) | Sensor structure | |
CN106095282A (en) | The touch operation method of key device, key device and terminal | |
CN107771311A (en) | Detect the input pressure in instruction pen | |
JP5731294B2 (en) | Input method and input device using input pad | |
JPH0773790A (en) | Merchandise selecting switch device for dispenser | |
JP3115140B2 (en) | Data input device | |
GB2354572A (en) | Touch- or proximity-sensitive switch for a computer pointing device | |
JP6546778B2 (en) | Touch detection keypad control device | |
CN102243931A (en) | Mouse key switch and mouse |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 07845164 Country of ref document: EP Kind code of ref document: A2 |