The invention relates to capacitive sensors for sensing the presence or touch of
`
`an object adjacent to a sensor. Capacitive position sensors have recently become
`
`increasingly common and accepted in human interfaces and for machine control. For
`
`example, in the fields of portable media players it is now quite common to find
`
`capacitive touch controls operable through glass or plastic panels. Some mobile
`
`( cellular) telephones are also starting to implement these kinds of interfaces.
`
`Many capacitive touch controls incorporated into consumer electronic devices
`
`or appliances provide audio and/or visual feedback to a user indicating whether a
`
`finger or other pointing object is present or approaches such touch controls. A
`
`capacitive sensing microprocessor may typically be comprised in touch-controlled
`
`devices which are arranged to provide an "on" output signal when a finger is adjacent
`
`to a sensor and an "off' output signal when a finger is not adjacent to a sensor. The
`
`signals are sent to a device controller to implement a required function dependent on
`
`whether a user's finger is in proximity with or touching an associated touch control.
`
`Some touch-controlled devices remain "on" or "active" despite the user having
`
`moved away from the device or a particular function no longer being required. This
`
`results in the device consuming a large amount of power which is not efficient. There
`
`is a need for an improved capacitive touch sensor which can regulate power usage.
`
`According to a first aspect of the present invention, there is provided a sensor
`
`for determining the presence of an object comprising: a sensing element, a
`
`capacitance measurement circuit operable to measure the capacitance of the sensing
`
`element, and a control circuit operable to determine whether an object is in proximity
`
`with the sensor based on a measurement of the capacitance of the sensing element, the
`
`control circuit also being operable to provide an output signal to control a function of
`
`an apparatus based on an object not being in proximity with the sensor and the output
`
`signal being produced after a predetermined time duration.
`
`According to a second aspect of the invention, there is provided an apparatus
`
`comprising a sensor according to the first aspect of the invention.
`
`The invention is described in further detail in Section 3.5 of the datasheet.
`
`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 1 of 32
`
`

`

`The control circuit of the sensor can determine whether an object or a user's
`
`finger is no longer in proximity with the sensor and based on a pre-determined time
`
`duration, the control circuit can produce an output signal automatically to prevent the
`
`capacitance measurement circuit from continually measuring changes in capacitance
`
`due to, for example, the perceived presence of an object in proximity with the sensor.
`
`Therefore, the control circuit is able to deactivate, turn-off, or power down the
`
`capacitance measurement circuit where an apparatus has inadvertently been left on or
`
`with the erroneous perception that a user is still present. The capacitance
`
`measurement circuit and the control circuit may be comprised in a general-purpose
`
`microcontroller under firmware control.
`
`As described in Section 3.5 in conjunction with the drawings, the control
`
`circuit of the sensor may be implemented by different methods - the signal output
`
`may be produced automatically after different pre-determined time durations to effect
`
`powering down the capacitance measurement circuit due to no presence of the user;
`
`the control circuit may be programmed by a user so that it may power down an
`
`apparatus based on a user-selected time duration; the control circuit output signals
`
`may be overridden, for example, to extend time durations before an apparatus is
`
`turned-off or to immediately turn-off an apparatus when a user is no longer present.
`
`The sensor of the invention may be useful in various applications, for
`
`example in kitchen appliances, light switches, headsets, and other electronic consumer
`
`devices. For example, a coffee machine incorporating a sensor of the invention may
`
`be programmed to power-down after a time period of, say, 30 minutes, where the
`
`coffee machine has been left on inadvertently. This will beneficially conserve energy
`
`use and minimise the possibility of damage and/or accidents caused by the coffee
`
`machine or glass container(s) overheating.
`
`The sensor of the invention may comprise different capacitance measurement
`
`circuits. For example, the fundamental principles underlying this type of sensor are as
`
`described in US 5, 730,165 and US 6,466,036. A sensor of the invention is described
`
`in detail in the QT102 product datasheet produced by QRG Ltd. (trading as Quantum
`
`Research Group). The sensor described in the QT102 datasheet may be used in
`
`apparatus or devices with one touch key; off course, the sensing element of the sensor
`
`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 2 of 32
`
`

`

`of the invention may comprise more than one key, for example two, three, or more
`
`keys. The sensor may also be based on other capacitance measuring techniques, such
`
`as described in US 6,452,514.
`
`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 3 of 32
`
`

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`Proximity Sensor with Auto-Off Function
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`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 4 of 32
`
`

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`Proximity Sensor with Auto-Off Function
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`D Request Early Publication (Fee required at time of Request 37 CFR 1.219)
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`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 5 of 32
`
`

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`Attorney Docket Number QAO
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`If the Assignee
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`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 6 of 32
`
`

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`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 7 of 32
`
`

`

`#~*QUANTUM
`
`#
`
`RESEARCH
`
`GROUP
`
`QT102
`QToucH TM CHARGE-TRANSFER
`IC
`
`This datasheet is applicable to all revision 2.3 chips
`
`The QT102 charge-transfer ('QT') touch sensor is a self-contained
`digital IC capable of detecting near-proximity or touch. It will project a
`touch or proximity field through any dielectric like glass, plastic, stone,
`ceramic, and even most kinds of wood. It can also turn small
`metal-bearing objects into intrinsic sensors, making them responsive to
`proximity or touch. This capability, coupled with its ability to
`self-calibrate, can lead to entirely new product concepts.
`
`It is designed specifically for human interfaces, like control panels,
`appliances, toys, lighting controls, or anywhere a mechanical switch or
`button may be found.
`
`OUT
`
`QT102
`1
`6
`
`TIME
`
`vss 2
`
`5
`
`VDD
`
`4
`
`SNS
`
`AT A GLANCE
`Number of keys:
`
`One, touch on/touch off plus a hardware programmable auto switch-off
`
`Technology:
`
`Patented spread-spectrum charge-transfer (direct mode)
`
`Key outline sizes:
`
`6mm x 6mm or larger (panel thickness dependent); widely different sizes and shapes possible
`
`Electrode design:
`
`Solid or ring electrode shapes
`
`Layers required:
`
`One
`
`Electrode materials:
`
`Etched copper, silver, carbon, Indium Tin Oxide (ITO), Orgacont ink
`
`Electrode Substrates:
`
`PCB, FPCB, plastic films, glass
`
`Panel materials:
`
`Panel thickness:
`
`Key sensitivity:
`
`Interface:
`
`Plastic, glass, composites, painted surfaces (low particle density metallic paints possible)
`
`Up to 50mm glass, 20mm plastic (electrode size dependent)
`
`Settable via capacitor
`
`Digital output, active high or active low (hardware configurable)
`
`Moisture tolerance:
`
`Good
`
`Power:
`
`Package:
`
`2V- 5.5V
`
`SOT23-6 RoHS compliant
`
`Signal processing:
`
`Self-calibration, auto drift compensation, noise filtering
`
`Applications:
`
`Patents:
`
`Control panels, consumer appliances, toys, lighting controls, mechanical switch or button
`
`QT ouch™ (patented Charge-transfer method)
`
`t Orgacon is a registered trademark of Agfa-Gevaert N.V
`
`#~*QUANTUM
`
`#
`
`RESEARCH
`
`GROUP
`
`AVAILABLE OPTIONS
`I
`S0T23-6
`TA
`-40°C to +85°C
`Q
`
`Copyright© 2007 QRG Ltd
`QT102_2R3.03_0707
`
`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 8 of 32
`
`

`

`Contents
`1 Overview
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`1.1 Introduction
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`1 .2 Electrode Drive
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`1 .3 Sensitivity
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`1.3.1 Introduction
`.....................................
`3
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`1.3.2 Increasing Sensitivity
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`1.3.3 Decreasing Sensitivity
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`1.4 Recalibration Timeout
`1.5 Forced Sensor Recalibration
`. . . . . . . . . . . . . . . . . . . . . . . . . . . 4
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
`1 .6 Drift Compensation
`1.7 Response Time
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
`1 .8 Spread Spectrum
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
`2 Wiring and Parts
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
`2.1 Application Note
`....................................
`5
`2.2 Cs Sample Capacitor
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
`2.3 Rs Resistor
`.......................................
`5
`2.4 Power Supply, PCB Layout
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
`3 Operation
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`3.1 Acquisition Modes
`...................................
`7
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`3. 1. 1 Introduction
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`3.1.2 OUT Pin 'On' (Fast Mode)
`. . . . . . . . . . . . . . . . . . . . . . . . . 7
`3.1.3 OUT Pin 'Off' (Low Power Mode)
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`3.2 Signal Processing
`
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`3. 2. 1 Detect Integrator
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`3. 2. 2 Detect Threshold
`3.3 Output Polarity Selection
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`3.4 Output Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`3.5 Auto Off Delay
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`3. 5. 1 Introduction
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`3. 5. 2 Auto Off - Predefined Delay
`. . . . . . . . . . . . . . . . . . . . . . . 8
`3.5.3 Auto Off- User-programmed Delay
`. . . . . . . . . . . . . . . . . . . . 8
`3.5.4 Auto Off- Overriding the Auto Off Delay
`. . . . . . . . . . . . . . . g
`3. 5. 5 Configuring the User-programmed Auto-off Delay
`. . . . . . . . . . . . . . . . . . . . . . . 12
`3.6 Examples of Typical Applications
`4 Specifications
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
`4.1 Absolute Maximum Specifications
`. . . . . . . . . . . . . . . . . . . . . . . 13
`4.2 Recommended Operating Conditions
`. . . . . . . . . . . . . . . . . . . . 13
`4.3 AC Specifications
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
`4.4 Signal Processing
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
`4.5 DC Specifications
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
`4.6 Mechanical Dimensions
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
`4.7 Marking
`.........................................
`15
`4.8 Moisture Sensitivity Level (MSL)
`........................
`15
`5 Datasheet Control
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
`5.1 Changes
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
`5.2 Numbering Convention
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
`
`#~#QUANTUM
`
`#
`
`RESEARCH
`
`GROUP
`
`2
`
`QT102_2R3.03_0707
`
`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 9 of 32
`
`

`

`1.3 Sensitivity
`1.3.1 Introduction
`The sensitivity of the QT102 is a function of such things as:
`
`•
`
`the value of Cs
`
`• electrode size and capacitance
`
`• electrode shape and orientation
`
`•
`
`•
`
`•
`
`the composition and aspect of the object to be sensed
`
`the thickness and composition of any overlaying panel
`material
`
`the degree of ground coupling of both sensor and
`object
`
`1.3.2 Increasing Sensitivity
`In some cases it may be desirable to increase sensitivity; for
`example, when using the sensor with very thick panels having
`a low dielectric constant. Sensitivity can often be increased by
`using a larger electrode or reducing panel thickness.
`Increasing electrode size can have diminishing returns, as
`high values of Cx will reduce sensor gain.
`
`The value of Cs also has a dramatic effect on sensitivity, and
`this can be increased in value with the trade-off of slower
`response time and more power. Increasing the electrode's
`surface area will not substantially increase touch sensitivity if
`its diameter is already much larger in surface area than the
`object being detected. Panel material can also be changed to
`one having a higher dielectric constant, which will better help
`to propagate the field.
`
`Ground planes around and under the electrode and its SNSK
`trace will cause high Cx loading and destroy gain. The
`possible signal-to-noise ratio benefits of ground area are more
`than negated by the decreased gain from the circuit, and so
`ground areas around electrodes are discouraged. Metal areas
`near the electrode will reduce the field strength and increase
`Cx loading and should be avoided, if possible. Keep ground
`away from the electrodes and traces.
`
`1.3.3 Decreasing Sensitivity
`In some cases the QT102 may be too sensitive. In this case
`gain can be easily lowered further by decreasing Cs.
`
`1.4 Recalibration Timeout
`If an object or material obstructs the sense electrode the
`signal may rise enough to create a detection, preventing
`further operation. To stop this, the sensor includes a timer
`which monitors detections. If a detection exceeds the timer
`setting (known as the Max On-duration) the sensor performs a
`full recalibration. This does not toggle the output state but
`ensures that the QT102 will detect a new touch correctly. The
`timer is set to activate this feature after - 30s. This will vary
`slightly with Cs.
`
`1 Overview
`
`1.1 Introduction
`The QT102 is a single key device featuring a touch on / touch
`off (toggle) output with a programmable auto switch-off
`capability.
`
`The QT102 is a digital burst mode charge-transfer (QT)
`sensor designed specifically for touch controls; it includes all
`hardware and signal processing functions necessary to
`provide stable sensing under a wide variety of changing
`conditions. Only low cost, noncritical components are required
`for operation.
`
`The QT102 employs bursts of charge-transfer cycles to
`acquire its signal. Burst mode permits power consumption in
`the microamp range, dramatically reduces RF emissions,
`lowers susceptibility to EMI, and yet permits excellent
`response time. Internally the signals are digitally processed to
`reject impulse noise, using a 'consensus' filter which requires
`four consecutive confirmations of a detection before the output
`is activated.
`
`The QT switches and charge measurement hardware
`functions are all internal to the QT102.
`
`1.2 Electrode Drive
`Figure 1.1 shows the sense electrode connections (SNS,
`SNSK) for the QT102.
`
`Figure 1.1 Sense Connections
`
`SENSE
`ELECTRODE
`
`Rs
`
`VDD
`
`5
`
`VDD
`
`Cx
`
`OUT 1
`
`TIME 6
`
`For optimum noise immunity, the electrode should only be
`connected to the SNSK pin.
`
`In all cases the sample capacitor Cs should be much larger
`than the load capacitance (Cx). Typical values for Cx are
`5 - 20pF while Cs is usually 2 - 50nF.
`
`Increasing amounts of Cx destroy gain, therefore it is
`important to limit the amount of load capacitance on both SNS
`terminals. This can be done, for example, by minimizing trace
`lengths and widths and keeping these traces away from power
`or ground traces or copper pours.
`
`The traces and any components associated with SNS and
`SNSK will become touch sensitive and should be treated with
`caution to limit the touch area to the desired location.
`
`A series resistor, Rs, should be placed in line with SNSK to
`the electrode to suppress electrostatic discharge (ESD) and
`Electromagnetic Compatibility (EMC) effects.
`
`#~#QUANTUM
`
`#
`
`RESEARCH
`
`GROUP
`
`3
`
`QT102_2R3.03_0707
`
`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 10 of 32
`
`

`

`1.5 Forced Sensor Recalibration
`The QT102 has no recalibration pin; a forced recalibration is
`accomplished when the device is powered up, after the
`recalibration timeout or when the auto-off override is released.
`
`However, supply drain is low so it is a simple matter to treat
`the entire IC as a controllable load; driving the QT102's Voo
`pin directly from another logic gate or a microcontroller port
`will serve as both power and 'forced recal'. The source
`resistance of most CMOS gates and microcontrollers are low
`enough to provide direct power without problems.
`
`1.6 Drift Compensation
`Signal drift can occur because of changes in Cx and Cs over
`time. It is crucial that drift be compensated for, otherwise false
`detections, nondetections, and sensitivity shifts will follow.
`
`Drift compensation (Figure 1.2) is performed by making the
`reference level track the raw signal at a slow rate, but only
`while there is no detection in effect. The rate of adjustment
`must be performed slowly, otherwise legitimate detections
`could be ignored. The QT102 drift compensates using a
`slew-rate limited change to the reference level; the threshold
`and hysteresis values are slaved to this reference.
`
`However, an obstruction over the sense pad, for which the
`sensor has already made full allowance, could suddenly be
`removed leaving the sensor with an artificially elevated
`reference level and thus become insensitive to touch. In this
`latter case, the sensor will compensate for the object's
`removal very quickly, usually in only a few seconds.
`
`With large values of Cs and small values of Cx, drift
`compensation will appear to operate more slowly than with the
`converse. Note that the positive and negative drift
`compensation rates are different.
`
`1.7 Response Time
`The QT102's response time is highly dependent on burst
`length, which in turn is dependent on Cs and Cx. With
`increasing Cs, response time slows, while increasing levels of
`Cx reduce response time.
`
`1.8 Spread Spectrum
`The QT102 modulates its internal oscillator by± 7.5 percent
`during the measurement burst. This spreads the generated
`noise over a wider band reducing emission levels. This also
`reduces susceptibility since there is no longer a single
`fundamental burst frequency.
`
`Figure 1.2 Drift Compensation
`
`Once an object is sensed, the drift compensation
`mechanism ceases since the signal is legitimately
`high, and therefore should not cause the
`reference level to change.
`
`The QT102's drift compensation is 'asymmetric';
`the reference level drift-compensates in one
`direction faster than it does in the other.
`Specifically, it compensates faster for decreasing
`signals than for increasing signals. Increasing
`signals should not be compensated for quickly,
`since an approaching finger could be
`compensated for partially or entirely before even
`approaching the sense electrode.
`
`#~#QUANTUM
`
`#
`
`RESEARCH
`
`GROUP
`
`4
`
`QT102_2R3.03_0707
`
`Petitioner STMICROELECTRONICS, INC.,
`Ex. 1021, IPR2021-01161 Page 11 of 32
`
`

`

`2 Wiring and Parts
`
`2.1 Application Note
`Refer to Application Note AN-KD02, downloadable from the
`Quantum website for more information on construction and
`design methods. Go to http://www.qprox.com, click the
`Support tab and then Application Notes.
`
`2.2 Cs Sample Capacitor
`Cs is the charge sensing sample capacitor. The required Cs
`value depends on the thickness of the panel and its dielectric
`constant. Thicker panels require larger values of Cs. Typical
`values are 2nF to 50nF depending on the sensitivity required;
`larger values of Cs demand higher stability and better
`dielectric to ensure reliable sensing.
`
`The Cs capacitor should be a stable type, such as X?R
`ceramic or PPS film. For more consistent sensing from unit to
`unit, 5 percent tole