I 1111111111111111 11111 111111111111111 1111111111 1111111111111111 IIII IIII IIII
`US00850254 7B2
`
`(12)
`
`United States Patent
`Philipp
`
`(IO) Patent No.:
`(45) Date of Patent:
`
`US 8,502,547 B2
`Aug. 6, 2013
`
`(54)
`
`CAPACITIVE SENSOR
`
`(75)
`
`Inventor: Harald Philipp, Ramble (GB)
`
`(73)
`
`Assignee: Atmel Corporation, San Jose, CA (US)
`
`( *)
`
`Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 163 days.
`
`(21)
`
`Appl. No.: 12/939,816
`
`(22)
`
`Filed:
`
`Nov. 4, 2010
`
`(65)
`
`Prior Publication Data
`
`US 2011/0043226 Al
`
`Feb. 24, 2011
`
`Related U.S. Application Data
`
`(63)
`
`Continuation of application No. 12/317,305, filed on
`Dec. 22, 2008, now Pat. No. 7,830,160, which is a
`continuation-in-part of application No. 11/868,566,
`filed on Oct. 8, 2007, now abandoned.
`
`(60) Provisional application No. 60/862,358, filed on Oct.
`20, 2006.
`
`(51)
`
`(2006.01)
`
`Int. Cl.
`GOJR 27126
`(52) U.S. Cl.
`USPC ............................ 324/686; 324/658; 324/681
`( 58) Field of Classification Search
`USPC .......................................... 324/658, 686, 681
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,121,204 A
`10/ 1978 Welch et al.
`4,264,903 A
`4/1981 Bigelow
`7,663,607 B2
`2/2010 Hotelling
`
`300"C
`
`, ,
`Lb0'\;
`
`0
`
`100
`
`7,830,160 B2
`7,875,814 B2
`7,920,129 B2
`8,031,094 B2
`8,031,174 B2
`8,040,326 B2
`8,049,732 B2
`8,179,381 B2
`2003/0043174 Al
`2004/0027395 Al
`2004/0196267 Al
`2004/0207605 Al
`2005/0052429 Al
`2005/0078027 Al
`2005/0113875 Al*
`
`11/2010 Philipp
`1/2011 Chen
`4/2011 Hotelling
`10/2011 Hotelling
`10/2011 Hamblin
`10/2011 Hotelling
`11/2011 Hotelling
`5/2012 Frey
`3/2003 Hinckley et al.
`2/2004 Lection et al.
`10/2004 Kawai et al.
`10/2004 Mackey
`3/2005 Philipp
`4/2005 Philipp
`5/2005 Ternes
`(Continued)
`
`........... 607/9
`
`DE
`DE
`
`FOREIGN PATENT DOCUMENTS
`19645907 Al
`5/1998
`19903300 Al
`8/1999
`(Continued)
`
`OTHER PUBLICATIONS
`
`U.S. Appl. No. 61/454,936, filed Mar. 21, 2011, Myers.
`
`(Continued)
`
`Primary Examiner - Vincent Q Nguyen
`(74) Attorney, Agent, or Firm - Baker Botts LLP
`
`ABSTRACT
`(57)
`Method and apparatus are provided for a capacitive sensor. In
`an example, a capacitive sensor can include a first sensing
`element, a sensing channel operable to generate a first signal
`indicative of first capacitance between the sensing element
`and a system ground, and a processor responsive to a change
`in the first capacitance between the first sensing element and
`ground. The processor can be configured to adjust a param(cid:173)
`eter value based on a first duration of the change in the first
`capacitance.
`
`17 Claims, 5 Drawing Sheets
`
`70
`\.
`
`175''C
`
`

`

`US 8,502,547 B2
`Page 2
`
`....... 73/780
`
`U.S. PATENT DOCUMENTS
`2006/0016800 Al
`1/2006 Paradiso et al.
`2006/0117862 Al *
`6/2006 Shank et al.
`2008/0094077 Al
`4/2008 Philipp
`2009/0051660 Al
`2/2009 Feland, III et al.
`2009/0115431 Al
`5/2009 Philipp
`2009/0315854 Al
`12/2009 Matsuo
`2010/0141277 Al
`6/2010 Philipp
`2012/0242588 Al
`9/2012 Myers
`2012/0242592 Al
`9/2012 Rothkopf
`2012/0243151 Al
`9/2012 Lynch
`2012/0243719 Al
`9/2012 Franklin
`
`FOREIGN PATENT DOCUMENTS
`1273851 A2
`1/2003
`1602882 Al
`12/2005
`2443296 A
`4/2008
`WO-03088176 Al
`10/2003
`WO-2006133976 Al
`12/2006
`WO-2007006624 Al
`1/2007
`WO-2007023067 Al
`3/2007
`WO-2007072294 Al
`6/2007
`WO-2010075463 Al
`7/2010
`WO-2010075463 A4
`9/2010
`WO 2012/129247
`9/2012
`
`EP
`EP
`GB
`WO
`WO
`WO
`WO
`WO
`WO
`WO
`WO
`
`OTHER PUBLICATIONS
`
`U.S. Appl. No. 61/454,894, filed Mar. 21, 2011, Rothkopf.
`"U.S. Appl. No. 11/868,566, Non-Final Office Action mailed Oct. 1,
`2009", 19 pgs.
`"U.S. Appl. No. 12/317,305, Non-Final Office Action mailed Oct. 1,
`2009", 15 pgs.
`"U.S. Appl. No. 12/317,305, Notice of Allowance mailed Apr. 12,
`2010", 7 pgs.
`"U.S. Appl. No. 12/317,305, Notice of Allowance mailed Jul. 19,
`2010", 6 pgs.
`"U.S. Appl. No. 12/317,305, Response filed Mar. 1, 2010 to Non
`Final Office Action mailed Oct. 1, 2009 and the Supplemental Office
`Action mailed Feb. 9, 2010", 14 pgs.
`"U.S. Appl. No. 12/317,305, Supplemental Non Final Office Action
`mailed Feb. 9, 2010", 12 pgs.
`"U.S. Appl. No. 12/703,614, Examiner Interview Summary mailed
`Aug. 23, 2010", 2 pgs.
`"U.S.Appl. No. 12/703,614, Non-Final Office Action mailed Jul. 28,
`2010", 7 pgs.
`"U.S. Appl. No. 12/703,614, Response filed Nov. 16, 2010 to Non
`Final Office Action mailed Aug. 23, 2010", 7 pgs.
`"International Application Serial No. PCT/US2009/069322, Search
`Report mailed May 7, 2010", 3 pgs.
`"International Application Serial No. PCT/US2009/069322, Written
`Opinion mailed May 7, 2010", 5 pgs.
`"UK Application Serial No. GB0719727.0, Combined Search and
`Examination Report, Date of Report: Feb. 22, 2008" 1 pg.
`
`U.S. Appl. No. 61/454,950, filed Mar. 21, 2011, Lynch.
`
`* cited by examiner
`
`

`

`U.S. Patent
`U.S. Patent
`
`Aug.6, 2013
`Aug. 6, 2013
`
`Sheet 1 of 5
`Sheet 1 of 5
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`US 8,502,547 B2
`US 8,502,547 B2
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`U.S. Patent
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`Aug. 6, 2013
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`Sheet 2 of 5
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`U.S. Patent
`U.S. Patent
`
`Aug.6, 2013
`Aug. 6, 2013
`
`Sheet 3 of 5
`Sheet 3 of 5
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`US 8,502,547 B2
`US 8,502,547 B2
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`U.S. Patent
`U.S. Patent
`
`Aug.6, 2013
`Aug. 6, 2013
`
`Sheet 4 of 5
`Sheet 4 of 5
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`US 8,502,547 B2
`US 8,502,547 B2
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`

`U.S. Patent
`
`Aug. 6, 2013
`
`Sheet 5 of 5
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`US 8,502,547 B2
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`

`

`US 8,502,547 B2
`
`1
`CAPACITIVE SENSOR
`
`CLAIM OF PRIORITY
`
`This application is a continuation of and claims the benefit
`of priorityunder35 U.S.C. §120 to Philipp, U.S. patent appli(cid:173)
`cation Ser. No. 12/317,305, entitled "CAPACITIVE POSI(cid:173)
`TION SENSOR," filed on Dec. 22, 2008, which is a Continu(cid:173)
`ation-in-Part of Philipp, U.S. patent application Ser. No.
`11/868,566, entitled "CAPACITIVE POSITION SENSOR,"
`filed Oct. 8, 2007, which claims the benefit of priority under
`35 U.S.C. §119(e) to Philipp, U.S. Provisional Patent Appli(cid:173)
`cation No. 60/862,358, entitled "CAPACITIVE POSITION
`SENSOR," filed on Oct. 20 2006, the benefit of priority of
`each of which is claimed hereby, and each of which are
`incorporated by reference herein in their entirety.
`
`BACKGROUND OF THE INVENTION
`
`5
`
`2
`contact time of, for example, 10 seconds. In the zoom mode
`an additional digital display is activated to show the current
`numerical value of the parameter being adjusted. In the zoom
`mode, only a fraction (e.g. 10%) of the original adjustment
`range is mapped onto the adjustment strip so that moving a
`finger across the full length of the sensor strip from left to
`right ( or right to left) will only increase (decrease) the current
`setting of the parameter value, thereby providing a finer
`adjustment. During this, fine adjustment, the display strip
`keeps its original function as a relative indicator of the full
`10 range between the minimum and maximum values.
`More generally, linear, curved and circular sensor strips for
`adjusting cooker settings have been known for many years,
`for example see U.S. Pat. No. 4,121,204 (resistive or capaci(cid:173)
`tive
`sensor), DEi 9645907 Al
`( capacitive
`sensor),
`15 DE19903300Al (resistive sensor), and EP1602882Al (opti(cid:173)
`cal sensor).
`WO2006/133976Al, WO2007/006624Al and WO2007/
`023067 Al are more recent examples of work on touch-sen(cid:173)
`sitive control strips for domestic appliances using capacitive
`20 sensors. These three patent applications were filed before the
`priority date of the present application, but first published
`after the priority date of the present application. In particular,
`WO2006/133976Al and WO2007/023067Al disclose sen-
`sors with a zoom function similar to the above-described
`EP1273851A2 which is used for setting a timer.
`WO2006/133976Al provides an adjustment strip with two
`operational modes. In the first mode the full parameter value
`range is mapped across the sensor strip. For example Oto 99
`minutes in a timer function. If a user wishes to set the timer to
`30 minutes, he touches the strip approximately one third way
`along. A parameter value of say 34 minutes is sensed by the
`capacitive sensor, and displayed to the user on a numeric
`display. Once the initial value has been set, the effect of
`touching the sensor field is automatically changed to a second
`mode in which the parameter value is decreased ( or
`increased) finely from the initially selected value by an
`amount that depends on the distance moved by the finger
`along the sensor strip. In the example, the user can then slide
`his finger from right to left to reduce the time from 34 minutes
`to the desired 30 minutes, using the display for visual feed(cid:173)
`back. In this way, the user can initially make a rough selection
`of the desired parameter value with a point and touch action,
`and then refine it to the exact value desired by a finger sliding
`action.
`WO2007 /023067 Al provides an adjustment strip with two
`operational modes that switch between mapping the full
`parameter value range across the sensor strip and a partial
`range selected to show the sub-range of parameter values
`between which the parameter is most often set by a user. The
`example of setting the timer on a cooker is given.
`While a zoom function is useful, prior art implementations
`of the zoom function have limitations regarding the manner in
`which the transition is effected from the full range mode to the
`zoom mode. In EP1273851A2, the user is made to wait for a
`certain time, 10 seconds in the specific example, until the
`transition occurs. On the other hand, in WO2006/133976Al
`the transition automatically occurs as soon as a value from the
`full range is selected. Neither transition mode is ideal, the
`former can be frustratingly slow for the user, and the latter
`automatic transition to fine adjustment is undesirable in the
`case that the initial touch sets a value that is a considerable
`way off what is intended by the user.
`
`The invention relates to capacitive position sensors, more
`particularly the invention relates to capacitive position sen(cid:173)
`sors for detecting the position of an object around a curved
`path.
`Capacitive position sensors are applicable to human inter(cid:173)
`faces as well as material displacement sensing in conjunction 25
`with controls and appliances, mechanisms and machinery,
`and computing.
`Capacitive position sensors in general have recently
`become increasingly common and accepted in human inter(cid:173)
`faces and for machine control. In the field ofhome appliances, 30
`it is now quite common to find capacitive touch controls
`operable through glass or plastic panels. These sensors are
`increasingly typified by U.S. Pat. No. 6,452,514 which
`describes a matrix sensor approach employing charge-trans-
`fer principles. Electrical appliances, such as TV's, washing 35
`machines, and cooking ovens increasingly have capacitive
`sensor controls for adjusting various parameters, for example
`volume, time and temperature.
`Due to increasing market demand for capacitive touch
`controls, there is an increased need for lower cost-per-func- 40
`tion as well as greater flexibility in usage and configuration.
`There exists a substantial demand for new human interface
`technologies which can, at the right price, overcome the tech(cid:173)
`nical deficits of electromechanical controls on the one hand,
`and the cost of touch screens or other exotica on the other.
`EP1273851A2 discloses a device for adjusting tempera(cid:173)
`ture settings, power settings or other parameters of a cooking
`apparatus. The device comprises a strip sensor which may be
`linear, curved or circular and may be a capacitive touch sensor
`or some other form of touch sensor. A linear display is 50
`arranged in parallel to the sensor. The capacitive touch sensor
`is sensitive to the touch of a finger and the display strip is
`made up of multiple display segments which illuminate to
`show the current touch setting as defined by a finger touch on
`the capacitive touch sensor. A predetermined calibration 55
`curve relating to a parameter to be adjusted is mapped onto
`the strip, the range extending from a minimum value to a
`maximum value. The minimum value may correspond to an
`off condition of the domestic appliance. Additional opera(cid:173)
`tional modes may be associated with the adjustment strip to 60
`ascribe new functions to the sensor strip. These can be
`selected by touching the display for a certain time. For
`example, a first additional mode can be entered by touching
`for 5 seconds, and a second additional mode by touching for
`10 seconds. One of the additional operational modes is a 65
`zoom mode which provides for fine adjustment of the param(cid:173)
`eter value. The zoom operational mode can be activated by a
`
`45
`
`SUMMARY OF THE INVENTION
`
`The invention provides an improved capacitive position
`sensor for an electrical appliance in which a desired param-
`
`

`

`US 8,502,547 B2
`
`5
`
`3
`eter value, in particular a color parameter value, can be more
`efficiently and accurately selected.
`According to one aspect of the present invention, there is
`provided a capacitive position sensor for detecting a position
`of an object comprising: a sensing element comprising a
`sensing path; at least one terminal connected to the sensing
`element; at least one sensing channel connected to the at least
`one terminal in which the sensing channel is operable to
`generate a signal indicative of capacitance between the ter(cid:173)
`minal and a system ground; means to determine a position of
`an object on the sensing element; and means to further refine
`the position of the object corresponding to a value in a param(cid:173)
`eter range of values.
`More particularly, this aspect of the invention provides a
`capacitive position sensor for setting a parameter or function
`to a desired value in a range of parameter or function values
`by determining the position of an object on a capacitive posi(cid:173)
`tion sensor, the capacitive position sensor comprising: a sens(cid:173)
`ing element comprising a sensing path; at least one terminal
`connected to the sensing element; at least one sensing channel
`connected to the at least one terminal in which the sensing
`channel is operable to generate a signal indicative of capaci(cid:173)
`tance between the terminal and a system ground; means to
`determine a position of an object on the sensing element;
`means to further refine the position of the object correspond(cid:173)
`ing to a value in the range of parameter or function values; and
`a processor operable to interpret and process the signal to
`determine the approximate position of an object on the sens(cid:173)
`ing path, the processor being configured to provide a first
`mode of the capacitive position sensor in which the range of 30
`parameter or function values is mapped onto the sensing path
`and in which the parameter or function can be set to approxi(cid:173)
`mately the desired value by a touch of the sensing path at a
`first point, and a second mode in which displacement of an
`object on the sensing element adjusts the parameter or func- 35
`tion from the value initially set in the first mode, wherein the
`processor is configured to switch from the first mode to the
`second mode responsive to capacitive coupling caused by
`moving displacement of an object along the sensing path in
`relation to the first point of touch.
`According to another aspect of the present invention, there
`is provided a method for determining the position of an object
`on a capacitive position sensor as hereinbefore defined, the
`method comprising bringing an object into proximity with the
`sensing element so as to determine a position of the object, 45
`initiating a change in mode of the sensor to respond to capaci(cid:173)
`tive coupling caused by moving displacement of an object on
`the sensor element, displacing an object on the sensing ele(cid:173)
`ment to select a value in a parameter range of values, and
`processing the signal to determine the selected parameter 50
`value.
`More particularly, this aspect of the invention provides a
`method for setting a parameter or function to a desired value
`in a range of parameter or function values by determining the
`position of an object on a capacitive position sensor, the 55
`capacitive position sensor comprising: a sensing element
`comprising a sensing path; at least one terminal connected to
`the sensing element; at least one sensing channel connected to
`the at least one terminal in which the sensing channel is
`operable to generate a signal indicative of capacitance 60
`between the terminal and a system ground; means to deter(cid:173)
`mine a position of an object on the sensing element; and
`means to further refine the position of the object correspond(cid:173)
`ing to a value in the range of parameter or function values, the
`method comprising: in a first mode of the capacitive position 65
`sensor in which the range of parameter or function values is
`mapped onto the sensing path bringing an object into prox-
`
`4
`imity with the sensing element at a first point so as to deter(cid:173)
`mine a position of the object and thereby initially set the
`parameter or function to approximately the desired value;
`initiating a change in mode of the sensor from the first mode
`to a second mode responsive to capacitive coupling caused by
`moving displacement of the object along the sensing path in
`relation to the first point of touch of the object on the sensing
`element; in the second mode displacing the object on the
`sensing element to adjust the parameter or function from the
`10 value initially set to the desired value; and processing the
`signal to determine the selected parameter or function value.
`In an embodiment of the invention, the capacitive sensor
`may work in a first mode and a second mode. In a first mode,
`a signal may be generated which is indicative of capacitive
`15 coupling of an object, for example a user's finger, with the
`sensing element. The signal generated in the first mode may
`provide an approximate position of an object in relation to a
`desired parameter value the user wishes to select. A processor
`may preferably be provided to interpret and process the signal
`20 to determine the approximate position of an object on the
`sensing element. It is preferred that in the first mode of opera(cid:173)
`tion, the capacitive sensor may generate a signal indicative of
`capacitive coupling caused by bringing an object into prox(cid:173)
`imity with a desired location on the sensor or by moving
`25 displacement of the object in proximity with the sensing
`element.
`In an embodiment of the invention, the capacitive sensor
`may enter a second mode of operation if moving displace(cid:173)
`ment of the object in proximity with the sensing element
`during a first mode of operation exceeds a minimum threshold
`value. For example, for a sensing element in the form of a
`rotary capacitive sensor, if a user displaces an object in prox(cid:173)
`imity with the sensing element during a first mode of opera(cid:173)
`tion by a minimum threshold angle in relation to a first point
`of touch of the object on the sensing element, the capacitive
`sensor may switch into a second mode of operation. The
`minimum threshold angle may be determined by an algorithm
`programmed into a microcontroller and the threshold angle
`may be set at different values depending on the sensitivity
`40 required and the parameter which is being adjusted. In one
`embodiment, the threshold angle may be set at 20 degrees
`before the capacitive sensor switches from the first mode to
`the second mode of operation. An approximate parameter
`value may be obtained in the first mode and in the second
`mode a desired parameter value may be selected.
`In the second mode of operation, an object may be dis(cid:173)
`placed in proximity with the sensing element by a pre-deter(cid:173)
`mined threshold value, for example 20 degrees, to effect an
`incremental change in the parameter value thereby allowing a
`desired specific parameter value to be selected. Advanta(cid:173)
`geously, a capacitive sensor of the invention operating in a
`first mode may allow a parameter value to be selected (which
`may be the desired value, or near to the desired value, the user
`wishes to select) and in a second mode the sensor may effect
`an incremental increase or decrease of the parameter value
`selected in the first mode. In the second mode, a parameter
`value may be increased or decreased by a pre-determined
`amount, for example .+-.1 unit, .+-.5 units, or .+-.10 units,
`based on the number of times an object is displaced on the
`sensing element exceeding a pre-determined threshold value.
`Therefore, the threshold value may correspond to an increase
`or decrease of the parameter value by, say, . +-.1 unit, and each
`time the threshold value is reached (n times) the parameter
`value will increase or decrease by .+-.1 (n times .+-.1).
`In an alternative embodiment of the invention, the capaci(cid:173)
`tive sensor may enter a second mode of operation by effec(cid:173)
`tively 'zooming-in' on a narrower range of parameter values,
`
`

`

`US 8,502,547 B2
`
`5
`compared to the parameter range displayed in the first mode,
`so that a user may accurately select a desired parameter value.
`The narrower range of parameter values shown during the
`second mode will be determined by the parameter value
`selected in the first mode, for example plus and minus 10 units 5
`from the value selected in the first mode. In the second mode
`of operation, an object may be displaced along the sensing
`element so as to select the desired parameter value.
`Preferably the processor for determining the position of an
`object in proximity with the sensing element in a first mode of
`operation may be operable for also determining the position
`of an object in proximity with the sensing element in a second
`mode of operation.
`Therefore, in the invention the capacitive sensor may func(cid:173)
`tion in a first mode of operation in which an approximate
`parameter value may be selected followed by a second mode
`of operation in which a specific parameter value may be
`selected. The range of parameter values associated with the
`capacitive sensor (i.e. the resolution) may determine whether
`a desired parameter value can be selected in the first mode of
`operation. The second mode of operation will allow a desired
`parameter value to be accurately selected, for example, either
`by zooming-in on a narrower range of parameter values
`around the parameter value selected in the first mode and
`displacing an object in proximity with the sensing element to
`select the desired value, or, by displacing an object in prox(cid:173)
`imity with the sensing element to exceed a pre-determined
`threshold value in order to change the parameter value
`selected from the first mode by one or more increments. The
`number of times the threshold value is exceeded may deter(cid:173)
`mine the number of times the parameter value is increased or
`decreased.
`A capacitive sensor of the invention may be incorporated
`into a control panel of an electronic appliance or gadget, for
`example a cooking oven, microwave oven, television, wash(cid:173)
`ing machine, MP3 player, mobile phone, or other multimedia
`device. Another example is a control panel for controlling
`lights or the background lighting of displays, such as a dim(cid:173)
`mer function to control brightness, or aspects of the color in
`color lighting, such as light emitting diode (LED) lighting.
`The control panel for the light may be integral with the light,
`in a remote control unit, or wall mounted on a wall plate. A
`wide range of parameters/functions may be controlled by the
`capacitive sensor of the invention, dependent on the type of
`electronic appliance in which the capacitive sensor is incor(cid:173)
`porated, for example, temperature, volume, contrast, bright(cid:173)
`ness, or frequency. Another example is to control color
`parameters, such as color hue, color saturation and color
`temperature in lights or displays, such as computer displays
`or television displays. The parameter or function to be con(cid:173)
`trolled may be selected prior to use of the capacitive sensor.
`Advantageously, the sensor has a higher degree of resolu(cid:173)
`tion in the second mode allowing a user to move their finger
`in proximity with the sensing element to select a specific
`parameter value. If the sensing element is in the form of a
`closed loop, a user may be able to scroll clockwise or anti(cid:173)
`clockwise around the sensing element to select the desired
`value. In the second mode for example, a 20 degree rotation
`may be equivalent to changing a parameter value by 1 unit.
`The amount of rotation required by an object on the sensing
`element to cause an incremental change in a parameter value
`may be varied dependent on the parameter or function being
`controlled. Control circuitry or a program-controlled micro(cid:173)
`processor may be used to control the degree of rotation
`required to cause a change in a parameter value.
`In a preferred embodiment of the invention, the sensing
`element is arcuate in shape. It is particularly preferred that the
`
`6
`sensing element is in the form of a closed loop for use in a
`rotary capacitive position sensor. In a rotary capacitive posi(cid:173)
`tion sensor embodiment, an object may be moved along the
`sensing element of the sensor for a plurality ofrevolutions and
`the distance moved by the object may determine the output
`signal which is generated by the sensing channel(s).
`In the first mode of operation of the capacitive sensor,
`capacitive coupling of an object in proximity with a sensing
`element may be detected to give an approximate position in
`10 relation to a range of values for a given parameter. If a user
`wishes to obtain different position data, the object may be
`removed from proximity with the sensing element and then
`brought into proximity with the said sensing element again. In
`other words, a user may initiate the first mode of the sensor
`15 again simply by retouching the sensing element. When the
`second mode of operation is initiated, a user may scroll the
`sensing element to select a specific value of a certain param(cid:173)
`eter. An output signal may be generated indicative of a spe(cid:173)
`cific parameter value when an object ceases displacement at a
`20 certain position on the sensing element. In an embodiment, if
`a user releases touch from the sensing element in a second
`mode and retouches the sensing element then the first mode of
`operation may be activated again.
`In an embodiment of the invention, the capacitive position
`25 sensor may further comprise one, two or more discrete sens(cid:173)
`ing areas in the centre region of a rotary sensing element.
`Preferably, if the sensing areas in the centre region of the
`sensing element sense capacitive coupling to an object, any
`signal produced from the sensing element is reduced or
`'locked out' using the Adjacent Key Suppression™ technol(cid:173)
`ogy described in the applicant's earlier U.S. Pat. No. 6,993,
`607 and U.S. application Ser. No. 11/279,402 both incorpo(cid:173)
`rated herein by reference. Any output signal from the rotary
`sensing element caused by capacitive coupling with an object
`35 may also lock out a signal from the central sensing areas.
`The sensing element may be embodied by a single resistor,
`for example it may comprise a resistive material deposited on
`a substrate to form a continuous pattern. This provides for an
`easy-to-fabricate resistive sensing element which can be
`40 deposited on the substrate in any one of a range of patterns.
`Alternatively, the sensing element may be made from a plu(cid:173)
`rality of discrete resistors. The discrete resistors may be alter(cid:173)
`nately connected in series with a plurality of conducting sense
`plates, the sense plates providing for increased capacitive
`45 coupling between the object and the resistive sensing ele(cid:173)
`ment. This provides for a resistive sensing element which can
`be fabricated from widely available off-the-shelf items. The
`disclosure ofWO2005/019766 is incorporated herein by ref(cid:173)
`erence as an example of the capacitance measurement cir-
`50 cuitry which may be used. Alternatively, a resistorless sensing
`element similar to that described in U.S. Pat. No. 4,264,903
`may be used to form the capacitive sensor of the invention.
`The resistive sensing element may have a substantially
`constant resistance per unit length. This provides for a capaci-
`55 tive position sensor having a simple uniform response. Where
`greater positional resolution is required and/or when employ(cid:173)
`ing a relatively long resistive sensing element, the resistive
`sensing element may include a plurality of terminals.
`The object to be detected may be a pointer, for example a
`60 finger or a stylus, which can be freely positioned by a user.
`Alternatively, the object may be a wiper held in proximity to
`the resistive sensing element, the position of the wiper along
`the resistive sensing element being detected by the capacitive
`position sensor. The position of the wiper may be adjusted by
`65 a user, for example by turning a rotary knob, or may be
`coupled to a shaft driven by connected equipment such that
`the capacitive position sensor can act as an encoder.
`
`30
`
`

`

`US 8,502,547 B2
`
`7
`Further objects of some embodiments of the invention are
`to provide for a sensor having high reliability, a sealed sur(cid:173)
`face, low power consumption, simple design, ease of fabri(cid:173)
`cation, and the ability to operate using off-the-shelflogic or
`microcontrollers.
`In U.S. Pat. No. 6,466,036, the applicant teaches a capaci(cid:173)
`tive field sensor employing a single coupling plate to detect
`change in capacitance to ground. This apparatus comprises a
`circuit employing repetitive charge-then-transfer or charge(cid:173)
`plus-transfer cycles using common integrated CMOS push- 10
`pull driver circuitry. This technology forms the basis of some
`embodiments of the invention and is incorporated by refer(cid:173)
`ence herein.
`Some definitions are now made. 'Element' refers to the
`physical electrical sensing element made of conductive sub- 15
`stances. 'Electrode' refers to one of the galvanic connection
`points made to the element to connect it to suitable driver/
`sensor electronics. The terms 'object' and 'finger' are used
`synonymously in reference to either an inanimate object such
`as a wiper or pointer or stylus, or alternatively a human finger 20
`or other appendage, any of whose presence adjacent the ele(cid:173)
`ment will create a localized capacitive coupling from a region
`of the element back to a circuit reference via any circuitous
`path, whether galvanically or non-galvanically. The term
`'touch' includes either physical contact between an object and 25
`the element, or, proximity in free space between object and
`element, or physical contact between object and a dielectric
`(such as glass) existing between object and element, or, prox(cid:173)
`imity in free space including an intervening layer of dielectric
`existing between object and element. Hereinafter the terms 30
`'circle' or 'circular' refer to any ellipsoid, trapezoid, or other
`closed loop of arbitrary size and outline shape having an open
`middle section.
`
`8
`capacitive sensor will depend on the type of electrical appli(cid:173)
`ance in which the capacitive sensor is incorporated. Param(cid:173)
`eters like volume, temperature, operating program, bright(cid:173)
`ness, contrast are some examples of functions that may be
`5 controlled by the capacitive sensor of the invention. In a
`preferred embodiment of the invention, the parameter to be
`controlled may be chosen from a pre-determined list of
`parameters so that a user may advantageously adjust different
`parameters on an electrical appliance or apparatus. The
`capacitive sensor 60 shown in FIG. 1 is set to control cooking
`temperature of a microwave o