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WO1998005025A1 - Capteur de position capacitif - Google Patents

Capteur de position capacitif Download PDF

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Publication number
WO1998005025A1
WO1998005025A1 PCT/US1997/010383 US9710383W WO9805025A1 WO 1998005025 A1 WO1998005025 A1 WO 1998005025A1 US 9710383 W US9710383 W US 9710383W WO 9805025 A1 WO9805025 A1 WO 9805025A1
Authority
WO
WIPO (PCT)
Prior art keywords
die
electrodes
predetermined number
charge
pointing device
Prior art date
Application number
PCT/US1997/010383
Other languages
English (en)
Inventor
Harald Philipp
Original Assignee
Airpoint Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Airpoint Corporation filed Critical Airpoint Corporation
Priority to US09/230,420 priority Critical patent/US6288707B1/en
Publication of WO1998005025A1 publication Critical patent/WO1998005025A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—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
    • G06F3/02—Input arrangements using manually operated switches, e.g. using keyboards or dials
    • G06F3/0202—Constructional details or processes of manufacture of the input device
    • G06F3/021—Arrangements integrating additional peripherals in a keyboard, e.g. card or barcode reader, optical scanner
    • G06F3/0213—Arrangements providing an integrated pointing device in a keyboard, e.g. trackball, mini-joystick
    • 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
    • G06F3/03547—Touch pads, in which fingers can move on a surface

Definitions

  • the sensor and its method of operation pertain to the determination of a position of an object adjacent a predetermined sensing area
  • the object is a part of an operator's body and an output from the sensor is used for moving a pointer or cursor on a computer screen under the operator's control
  • Representative similar devices are commonly known as 'mice', trackballs, joysticks, touch screens, touch pads and the like, and are collectively referred to as pointing devices
  • Single-electrode capacitive sensors for sensing the proximate presence of an object are commonly used as non-contact electric switches (e g , elevator call buttons), as part of a water valve controller for operating a wash basin valve in a public restroom, for monitoring the flow of objects on an assembly line and the like
  • Sensors of this sort are commonly configured to provide a binary output and operate by measuring a value of electrical capacitance to an electric ground If the sensor is configured as a "proximity sensor” it provides an output determinative of proximate presence when the value of the measured capacitance exceeds a predetermined threshold valve If the sensor is configured as a "motion sensor” it provides the determinative output when the rate of change of capacitance exceeds a predetermined threshold value
  • Multi-electrode capacitive sensors having a plurality of electrodes disposed about a predetermined sensing area can determine the position of an object adjacent the area and, by making multiple measurements over a period of time, can determine the direction and speed of motion of the object
  • multi-electrode capacitive sensors e g , for controlling the intensity of a light or sound source responsive to an operator moving his or her hand across the sensing area
  • the application that appears to be of greatest interest is that of providing an input to a computer that uses the input to determine the position of a cursor on an associated display
  • Popular laptop pointing devices include inter alia (a) small trackballs on or adjacent the keyboard, (b) tiny joysticks interposed among the keyboard keys, (c) capacitive touch pads, and (d) accessory mice to be used near the laptop, but not built into it
  • the joystick has been found wanting by many, as it is a limited movement 'velocity' device That is, small amounts of force applied laterally to the stick cause the pointer to accelerate to a velocity proportional to the force and to move in the direction of the applied force
  • This less than convenient method requires considerable accommodation on the part of the user
  • Capacitive finger touch pads which may share the same housing as the keyboard but which do not share an active typing area of the keyboard, offer a significant improvement by presenting a more substantial surface area to the user, and allowing movements that are generally more intuitive than those of a joystick.
  • Ng et al. in US 4,476,463, disclose a pointing device responsive to the position of a user's finger adjacent a computer display overlaid with a resistive sheet having three or more electrodes spaced thereabout
  • the position of the user's finger is determined from a sequence of capacitive measurements, each of which involves charging the sheet and then transferring charge from the sheet into an A to D converter
  • this charge /discharge /measure sequence may be repeated a predetermined number of times to obtain an average value from which a distance (relative to the one electrode at which the measurement is taken) is determined
  • the position is determined (or over-determined) as the point satisfying all the distance criteria
  • Ng et al 's teaching embraces an arrangement for resetting reference levels in the capacitive measurement to adapt to environmental changes
  • Yoshikawa et al in US 4,680,430, teach a pointing device responsive to the position of a user's finger (which is capacitivelv coupled to ground) above a uniformly resistive layer of material
  • Yoshikawa et al teach the use of their device as a coarse-resolution touch-screen input device, but do not disclose integrating their pointing device with a keyboard or keypad
  • Matzke et al in US 4,736,191, teach a multi-electrode capacitive pointing device comprising an array of electrodes symmetrically disposed about a central point Their array, which is operated by sequentially charging and discharging the electrodes to capacitively determine the position of a user's finger adjacent the device, is disposed near the keyboard of a computer
  • Boie et al in US 5,463,388, teach a computer mouse or keyboard input device utilizing capacitive sensors Their input device employs an array of metallic electrodes and detects the position of a user's finger from a centroid of capacitance values The position information is used to either move the cursor (if the apparatus is being used as a pointing device) or to select a character to be input (if the apparatus is being used as a keyboard) Boie et al do not disclose integrating their pointing device with a keyboard or a keypad
  • Gerpheide et al in US 5,565,658, teach a touch-pad capacitance-based computer pointing device using two orthogonal arrays of metallic stripes separated by an insulator They employ an arrangement tn which the capacitance measurement is made synchronously with a reference frequency selected to not be coherent with the interfering signal
  • a preferred embodiment of the invention provides a multi-electrode capacitive sensor for a computer pointing device, wherein the sensor is integrated with the computer's keyboard and employs ratiomet ⁇ c capacitive sensing means
  • the preferred sensing means comprises both a circuit for charging a resistive layer and a predetermined number of switching elements, each of which is respectively connected to one of the predetermined number of electrodes, each of which is spaced apart from others of the electrodes
  • the switching elements hereinafter referred to as “charge transferring switches” or “discharging switches” remove charge from the resisuve layer and transfer it to a multi-channel charge detection circuit
  • charge transferring switches or “discharging switches”
  • the invention comp ⁇ ses a resistive g ⁇ d-shaped member having grid lines intermediate adjacent ones of the keys of at least a portion of a computer's keyboard and having a sheet resistance that is in excess of ten ohms per square but less than one megohm per square.
  • Electrodes are attached adjacent the periphery of the reststive grid at a plurality of widely separated points (e g , the four comers or sides of a rectangular g ⁇ d) so as to be conterminous with the sensing area
  • the electrodes provide inputs to a multi-channel charge detector having one channel associated respectively with each electrode
  • the capacitive sensor is used to determine the posiuon of a user's fingers, hand, or other body part, or of a suitable hand-held object adjacent the keyboard or a defined portion thereof
  • It is a specific object of the invention to provide a computer pointing device comprising a capacitive sensor having a plurality of electrodes disposed adjacent a circuit board or other generally planar fixed support or baseplate underlying a keyboard
  • This pointing device senses the presence of an object adjacent the keycaps and can be operated by a user who skims his or her fingers over the keyboard without having to depress any of the keys
  • It is an additional object of the invention to provide a computer pointing device comprising a resistive layer disposed adjacent a keyboard and a capacitive sensing means electrically connected to the resistive layer. It is a specific object of the invention to provide such a pointing device wherein the layer comp ⁇ ses a g ⁇ d having resistive g ⁇ d lines disposed between adjacent ones of predetermined keys on the computer keyboard It is an additional specific ob j ect of the invention to provide such a pointing device wherein the layer has a resistivity greater than ten ohms per square and less than one million ohms per square.
  • RFID radio frequency interference
  • Figure 1 is a partially cut-away elevational view of a computer keyboard with a pointing device of the invention installed therein
  • Figure 2 is a partial cross-sectional view generally taken along the iine 2-2 of Fig 1.
  • Figure 3 is a plan view of a preferred configuration of a resistive layer portion of the invention
  • FIGS 4, 5 and 6 are plan views of alternate electrode array configurations
  • Figure 7 is a partly schematic plan view of a single keycap configured for use with a one-dimensional capacitive position sensor
  • Figure 8 is a general schematic diagram of a circuit used for charging and discharging a capacitive sensor
  • Figure 9 is a schematic diagram of a preferred circuit for measuring a capacitance change from a single capacitive sensor, as may be used for sensing a position of a user's hand in the pointing device of the invention
  • Figure 10 is a schematic diagram of a preferred circuit for sensing the position of a user's hand adjacent an array of capacitive plates
  • a pointing device for a computer 10 allows a user to move a display indicator 12 (which may have the shape of a cross-hairs, arrow, or blinking rectangle, all of which are hereinafter referred to with the conventional term "cursor" ) about on a display 14
  • a pointing device of the invention comp ⁇ ses a resistive sheet or layer 16 disposed in a planar configuration beneath the tops of the keycaps 18 of a portion of a keyboard 20, as well as one or more touch pads 22 preferably disposed on a side or front surface of the keyboard 20
  • a patterned electrode array 17 can be employed instead of the resistive layer 16.
  • Both of these arrangements provide a keyboard 20 that can be used in a conventional fashion, or that can be switched over to a pointing mode of operation when the user touches a predetermined one of the mode selector pads 22
  • the user provides the control input bv skimming his or her curled fingers 24 over the tops of the keyboard 20 This can be done without depressing any of the keys in the active typing region of the keyboard, without changing the curl of the fingers, and even without altering the number of fingers proximate to or in contact with the keycaps 18
  • sensing circuitry 40 of the invention which has an output to cursor location controlling means so that the cursor 12 moves responsive to a motion of the user's hand or fingers 24 It will be understood by those reading the disclosure hereinafter made that although various arrangements are disclosed for a two-dimensional pointing apparatus and method, the same apparatus and method could be employed for one dimensional pointing (e g , in an arrangement having only two electrodes) or for
  • the actual active sensing area, e g , the portion of the keyboard 20 encompassed by or conterminous with the sensing layer 16, can be a sizable fraction of total keyboard area
  • the invention has functioned using as little as one third to as much as the entire keyboard area
  • the resistive laver 16 takes the form of a parallelogram encompassing that portion of a conventional QWERTY keyboard bounded bv the "u", "m", "/", and "p" keys
  • the surface area can be made to correspond to absolute coordinate positioning instead of differential positioning as is done with most contemporaiy pointing devices
  • Absolute positioning allows the user to mentally map the display screen 14 with hand positions that do not vary Even when errors are made in hand position relative to the screen, as when the user places her fingertips on a section of keyboard thought to correspond to an icon, only small corrections need be made This method is conceptually and practically superior
  • a computer mouse, or other pointing device commonly comprises two or more keys that the user can momentarily actuate, or "click", to select a program feature indicated on the display 14 and pointed to with the cursor 12
  • clicking may be provided by the mode selecting means 22
  • a pointing device of the invention could comp ⁇ se three touch switches 22, one of which would be used to select the pointing or "mousing" function, and die other two of which could be used analogously to die two buttons on a conventional mouse. It will be understood to those skilled in the art that odier approaches to selecting a program feature could also be used widi die pointing device of the invention once the pointing mode had been selected.
  • specific keys e.g., the "e” and “c” keys on a conventional "qwerty" keyboard
  • Placement of the field electrodes can be under any desired portion of the keyboard, including die left or right portions of the main keyboard, or under a numeric keypad subsection.
  • near-duplicate field generating structures can be inserted into both left and right portions of a keyboard and means can be provided to select one of these two portions in order to accommodate both left- and right-handed users.
  • a preferred sensor comprises a resistive layer 16 disposed across a region encompassing a plurality of keycaps 18 of a keyboard 20 of the conventional type wherein an upper portion of a key, e.g., a keycap 18, is movable along a line generally perpendicular to a fixed support 23 between a resting position in which the keycap is most distal from the fixed support and an actuating position in which die keycap is most proximal to the fixed support.
  • die most distal position will hereinafter be referred to as the "uppermost" position, while the most proximal will be called the 'lowermost”).
  • a characteristic output, uniquely associated widi diat key is supplied to die computer.
  • the moving keycaps communicate with respective momentary contact switches 21 disposed on the fixed surface 23 (e.g., a circuit board) by means such as an array of parallel (and generally vertical) plungers 30.
  • non-contact position sensing means e.g., a Hall effect device or a dedicated capacitive sensor
  • the sensing and pointing means of the invention are independent of the arrangement used by the keyboard for supplying character outputs to the computer.
  • the preferred resistive layer 16 has a plurality of throughholes 28 formed therethrough, each of the throughholes accommodating a portion of a respective key switch 21 so that the resistive layer is disposed thereabout.
  • the diroughhole 28 need only accommodate a relatively narrow plunger 30.
  • a relatively wide lower portion of the keyswitch 21 extends upwards from the circuit board 23 through the diroughhole.
  • diat in order to avoid shorting out conducting traces on the printed circuit board 23, an insulating film 35 may be provided between die resistive film 16 and d e fixed substrate 23. It will be recognized to those skilled in die art of capacitive sensing diat conductive sheets (not shown) may be required at various locations on or behind die circuit board in order to shield the back side of die sensing array and to provide a ground plane. Although pointing devices of the invention have been retrofitted into several commercially available keyboards, it is expected that a production version of the sensor will be designed in conjunction wid die associated keys and circuit board.
  • resistive layer of that sort could, for example, serve as one of the layers of material making up a membrane or capacitive keyboard. Touch-screens and keyboards of this type, because they have little or no perceptible key motion, are generally perceived as being inconvenient to use, but, because they are easily environmentally sealed, are often used in industrial and food service applications.
  • a resistive layer of the sort depicted in Fig. 2 that has upstanding wall-like portions 32 filling gaps between adjacent keycaps 18.
  • These upstanding wall-like portions 32 may extend in only one direction along die keyboard (e.g., along the QWERTY keyboard's X-axts as a first ridge disposed between die uiop[ keys and the jkl;' keys and as a second ridge disposed between the jkl;' keys and the nm,./ keys) or may extend in bodi the X and Y directions so as to define an "eggcrate" set of walls surrounding each key in an active portion of die keyboard.
  • the resistive layer 16 may be a generally flat geometrical sheet, or it may comprise a honeycomb array of short tubular segments.
  • a variety of resistive keycap portions can be used instead of the preferred film 34.
  • a prior art membrane keyboard which already comprises a conductive elastomeric layer having an appropriate sheet resistivity for use in the present invention
  • a resistive layer having a honeycomb structure can be made from a plurality of tubular segments joined at points of circumferential contact among adjacent ones of die segments, it will be noted that it is the electrical contact among segments that is of significance, and not die mechanical joining.
  • each keycap used in a active region of die keyboard had a resistive skirt on its outside lateral surface 33 (e g , if the keycap was made of a material having an appropriate resistivity, or if the lateral walls of the keycap were coated with such an appropriate film 34) and in which all of diose keycaps were in lateral rubbing contact
  • the array of resistive skirts would be electrically and functionally equivalent to the physical honeycomb array forming the layer 16 depicted in Fig 2
  • die mechanical interface between grid and keys as shown in Fig 2 can be altered significandy and still operate in general accord with die invention
  • the intent is merely to make contact substantial enough between grid and keys, with sufficient reliability, so as to allow finger(s) to be capacitively detected in a smooth and uninterrupted fashion without lumpiness in die detection field
  • Non- lineanties in the field occurring over the planar surface can be corrected for in software with a look-up table and an interpolation method, or in a madiematical algonthm designed for the purpose
  • a single finger 24 is shown in the depiction of Fig 2
  • the user skims more than one finger e g , the depiction of Fig 5, which is believed to be an ergonomically preferable approach
  • the user skims more than one finger (e g , the depiction of Fig 5, which is believed to be an ergonomically preferable approach) over the active pointing area of the keyboard, he or she will find a smoother response because the centroid of the set of fingers is sensed
  • die layer 16 is a four-sided plane figure with a metal electrode 36 at each of its four comers (not shown) or at the center points of each of its four sides, as depicted in Fig 3
  • Each of the electrodes 36 is connected by a wire 38 to a respective input of a four channel capacitive sensing circuit 40 of a sort to be discussed hereinafter with particular reference to Figs 8-10
  • a user's fingertips 24 travel across the keys, die resultant increased capacitance is sensed by each channel of the four channel sensor 40
  • Ratios of the outputs of the four channels are taken, and with further processing, such as two dimensional interpolation and lowpass filtering, the fingertips' position can be ascertained with reasonable precision
  • further processing such as two dimensional interpolation and lowpass filtering
  • the four-sided preferred layer 16 of the invention may be disposed under the keycaps 18 of a conventional qwerty keyboard with a first x-axis electrode (denoted as XI) adjacent die "D" key, a second x-axis electrode (denoted as X2) adjacent the "L", a first y-axis electrode adjacent the "7” and die second v-axis electrode adjacent the "N"
  • XI first x-axis electrode
  • X2 second x-axis electrode
  • X2 first y-axis electrode adjacent the "7”
  • the relative displacement is C(X1)/C(X2) if C(X1) > C(X2), and is C(X2)/C(X1) if C(X1) ⁇ C(X2).
  • the same sort of processing is used for the Y axis. It will be understood to those skilled in the art that one may normalize the capacitance values to compensate for hand size and finger position, e.g., by subtracting a correction term K from each value, so the relative X-axis displacement is calculated from (C(X1) - K)/(C(X2) - K), etc.
  • die ratiometric capacitive measurement when applied to computer pointing, is not confounded by finger height above the keys, which would odierwise lead to erroneous and unpredictable positioning.
  • signal amplitude which is related to fingertip surface area and height above the keys
  • This processing should occur in each of die two dimensions. Should the signal of any one of the sides of die layer fall below a minimally acceptable threshold value, processing may be halted and the screen pointer held stationaiy.
  • d e value of die resistance of the resistive film 16 is of some concern. If, for example, this layer were a perfect conductor it would charge and discharge instantaneously and all four capacitance values would be identical, regardless of where the user's finger was placed. More generally, a lower limit on die sheet resistance is dictated by the desired spatial resolution. This lower limit can be extended to below one hundred ohms per square by putting in a summing junction (e.g., using an op amp).
  • one upper limit on the sheet resistivity is set by speed requirements - ⁇ e., the time required to drain charge from the layer should not be so long as to cause a perceptible lag in pointing
  • the working upper limit on sheet resistivity anses from inhomogeneity - i.e , as sheet resistivity increases many resistive g ⁇ d arrangements of the invention become too inhomogeneous to be useful.
  • the capacitance from film to fingers is less than about 1 picofarad and die relevant RC time constant must be such diat die ratios can be repeatably and accurately determined without severe amplification lest noise affect the measurement
  • die relevant RC time constant must be such diat die ratios can be repeatably and accurately determined without severe amplification lest noise affect the measurement
  • resistors made from materials with sheet resistivities in the preferred k ⁇ /square range commonly suffer from problems associated with spatial inhomogeneities across a sample that is several centimeters on a side, with lack of sample-to-sample reproducibility, and with high temperature coefficients of resistance All of these effects could be deleterious to a capacitive or resistive method of moving a cursor to absolute coordinates on a display, but have not been found to be of serious concern for a pointing device
  • die human operator can adjust to accommodate for such effects - e g , a highly inhomogeneous sheet may be perceived as being die same as a conventional mouse widi a slight acceleration curve
  • ratiometric measurements are not affected by a high temperature coefficient of resistance as long as all portions of the layer experience the same temperature change
  • a ratiometric capacitive sensor can also be made using an array of patterned metallic electrodes 42 disposed on an insulating layer or substrate 44, where the electrode geometry is selected to generate a varying capacitive output as a proximate body (e g , a stylus or the user's finger) moves across the electrode array
  • a proximate body e g , a stylus or the user's finger
  • die shaped electrode embodiments also preferably employ an overlay of some sort to set a minimum distance between the pointing object and the electrodes in order to prevent a user from becoming aware of the discrete electrodes.
  • a sufficiendy thick piece of plastic above the shaped electrodes for example, "blends" the fields from the various electrodes so as to provide a smooth response to the user's pointing motions.
  • the array 42 depicted in Fig 4 This arrangement comp ⁇ ses four interspersed electrode sets, two for each dimension.
  • the x-axis sets which are triangular, are easier to see and understand
  • a first set of triangles 46 are all electrically connected together to an output buss denoted as XI
  • the second set 48 are also connected together to an output labeled X2
  • the position of a user's hand with respect to the x-axis can be ascertained from the ratio of signals from XI and X2 Because capacitance is direcdy proportional to surface area, and because the plates connected to XI aggregate to a greater surface area to the left dian do the plates connected to X2 (and vice versa) the ability to take the ratio of X1 /X2 or X2/X1, as discussed supra, is preserved so long as a great enough finger area is over the pattern 42 at a close enough range to provide sufficient signal strength This design also prevents fingertip location on the Y axis from affecting the X measurement
  • a corresponding set of plates are connected to the Yl and Y2 busses
  • Fig 5 Yet another electrode arrangement is depicted in Fig 5, which also depicts die position of four of a user's fingers in phantom
  • the triangular y-axis electrodes 52, 53 are used for ratiometric surface area determination as described in conjunction with die triangular x-axis electrodes 46,48 depicted in Fig 4
  • the x-axis determination is done in a yet different manner — it localizes the x-axis position of d e user's hand according to the number of fingers 24 (actually the ratio of finger surface area) disposed over the two x electrodes 54, 55 Should a hand stray outside the boundary zone (either to the left or right) a respective x-axis output will experience a dramatic loss in signal and processing will ordinarily be made to cease and die pointer or cursor will stop moving
  • Figure 6 depicts still another electrode arrangement in which a pair of triangular x-axis electrodes 46, 48 and a pair of triangular v-axis electrodes 52, 53 are employed to detect the centroid of a set of user's fingers disposed above the patterned electrode array in accordance with die mediods described supra
  • the sheet may be charged through any one of die electrodes 17, but all of the electrodes 17 must be discharged simultaneously
  • die electrodes were connected to the charge sensor sequentially, rather than simultaneously, the charge would be transferred via the first electrode connected, and die apparatus would fail to provide an indication of position
  • shaped metal electrodes disposed on an insulating layer it is necessary to connect each of the electrodes to a charging source, but it is not necessary to discharge all of them simultaneously.
  • a charging switch 56 which is preferably a low resistance switching element, such as a transistor controlled by a signal on a charging control line 57, is used to transfer charge from a voltage supply 58 to a capacitive sensing electrode 60, which may be either one of the electrodes 36 disposed on the resistive sheet 16 or one of an array of patterned electrodes 42 disposed on an insulating substrate 44.
  • the capacitive sensing electrode is preferably connected for a first interval, the length of which is selected to be long enough to allow the sensing electrode 60 to reach a saturation voltage, following which the charging switch 56 is opened, and, after waiting for a suitable short period to prevent switch crossover conduction, a signal sent over a discharging control line 63 causes a charge transferring switch 62 to close and thereby to connect the sensing electrode 60 to a charge measurement means 64 so as to rapidly discharge the sensing electrode 60 thereinto Because the switches 56, 62 have intrinsic internal capacitances which inject charge into the charge detector 64, and because the sensing electrode 60 may have a very large inherent capacitance, it is often desirable to cancel these charges as fully as possible to prevent saturating the charge detector 64 with diese background signals.
  • a charge subtractor or cancellation circuit 66 may be provided in some embodiments of die invention to remove charge from the charge detector 64 Because only the charge detector's offset is affected by the charge subtractor 66, there is no change in gain of the charge detector and the overall system sensitivity remains unaffected. As is conventional in contemporary electronic designs, one may conveniendy provide for the operation and control of the vanous circuit functions discussed widi respect to Fig. 8 by means of a microprocessor 68.
  • Fig. 9 shows a schematic circuit diagram of an exemplar circuit of the sort described hereinbefore with respect to Fig. 8.
  • die switches 56, 62 are p- and n-channel mosfet transistors of types BSS110 and BSN10, respectively, both of which have integral source-drain diodes.
  • An opuonal resistor 70 adds damping and prevents ringing in the line running to the sensing electrode 60.
  • the switches 56, 26 are pulsed direcdy from the microprocessor 68 with l ⁇ sec pulses, earlier embodiments of the circuit operated with external pulse networks (not shown).
  • An amplifier circuit 78 is used with an 8-bit DAC 79 to provide an adjustable measurement offset of the signal.
  • the analog to digital converter 80 integral to the preferred PIC16C74 microcontroller 68 is only 8 bits, and thus has limited dynamic range. By adding a large external gain with offset capability, the system obtains an 8-b ⁇ t 'window' subrange into a 13-bit measurement space (3 offset bits provide overlap within each 8-bit window subrange).
  • Fig 10 one finds a schemauc depiction of a four channel sensor circuit 40 for use with any of die capacitive position sensing electrode arrangements 60 of the invention.
  • the sensor circuit 40 is depicted as having the four capacitive electrode inputs hereinbefore labeled as XI, X2, Yl, and Y2, as well as having two inputs (labeled as A and B) from respecuve capacitive touch pads 22.
  • a charging control line 57 in this embodiment is used to simultaneously charge all six of the capacitive inputs XI, X2, Yl, Y2, A & B It will be understood to those skilled in the art that in an embodiment of die invention using a single resistive grid or layer 16, a single charging switch 56 could be employed to charge the layer because all four electrodes 36 are connected dirough the layer 16.
  • the charging control line 57 may be omitted and die charging switches 56 replaced with a pull-up resistor constandy connecting the various electrodes to the voltage supply.
  • the pull-up resistor has a resistance chosen to provide an RC time constant greater than die discharge interval used to discharge the layer into the array of charge detectors.
  • diis resistance is between fifteen and twenty five thousand ohms Regardless of how one chooses to charge the layer 16, however, it is preferred that die four channels of charge transfer act simultaneously when transferring charge to the charge detectors - e , as indicated in Fig 10 by the use of a single discharging control line 63 to discharge all the charged electrodes After the transfer, or burst of transfers, has occurred, an analog multiplexer 82 selects which of the six charge detector capacitor outputs is to be fed to die amplifier 84 and ADC 86 and dience to die microcomputer Additionally, an array of reset switches 88 controlled by a reset control line 90 is activated after each pulse or burst of pulses to reset the capacitive inputs to a known reference (e g , to ground) It will be clear to those skilled in the art that many of die circuit elements depicted in the Fig 9 in die detailed schematic for a single channel sensor have been omitted from the schemauc of Fig 10 in the interest of clarity
  • the invention provides apparatus and method for human-computer interfaces, and is believed to be of particular utility when used with a small, and generally, portable computers of the types commonly referred to as “notebook, 'laptop” or “palmtop” computers, as well as “personal digital assistants” "network computers”, and the like.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Input From Keyboards Or The Like (AREA)

Abstract

Un capteur de position capacitif multi-électrode fait partie d'un dispositif de pointage informatique pouvant être intégré dans le clavier (20) d'un ordinateur et utilisant des techniques de détection capacitive logométriques. Cette approche permet à l'utilisateur d'un ordinateur de déplacer un curseur (12) sur un affichage (14) par effleurement du clavier (20) avec les doigts (24) sans appuyer effectivement sur n'importe laquelle des touches. L'agencement de détection préféré comprend un circuit destiné premièrement à charger une couche résistive (16) disposée sur une partie active du clavier, et ensuite à décharger la couche (16) par connexion simultanément de chacune des électrodes espacées (36) à des entrées respectives d'un circuit (40) de détection de charges multicanaux. Pour un dispositif de pointage unidimensionnel, on utilise au moins deux commutateurs (62) de transfert de charge et au moins deux électrodes (36), deux étant le nombre préféré. Pour un dispositif de pointage bidimensionnel, on utilise au moins trois commutateurs (62) de transfert de charge et électrodes (36), quatre étant le nombre préféré.
PCT/US1997/010383 1996-07-29 1997-06-12 Capteur de position capacitif WO1998005025A1 (fr)

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US09/230,420 US6288707B1 (en) 1996-07-29 1997-06-12 Capacitive position sensor

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US1610796P 1996-07-29 1996-07-29
US60/016,107 1996-07-29
US2388996P 1996-08-13 1996-08-13
US60/023,889 1996-08-13

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US09/230,420 A-371-Of-International US6288707B1 (en) 1996-07-29 1997-06-12 Capacitive position sensor
US09/940,006 Division US6535200B2 (en) 1999-01-25 2001-08-27 Capacitive position sensor

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WO1999052027A1 (fr) * 1998-04-06 1999-10-14 Hans Rudolf Sterling Positionnement du curseur sur l'ecran d'affichage d'un ordinateur
EP1197835A3 (fr) * 2000-10-03 2003-02-05 Nokia Corporation Appareil d'interface utilisateur
US6611921B2 (en) 2001-09-07 2003-08-26 Microsoft Corporation Input device with two input signal generating means having a power state where one input means is powered down and the other input means is cycled between a powered up state and a powered down state
WO2003050671A3 (fr) * 2001-12-11 2003-11-27 Wolfgang Fallot-Burghardt Clavier d'ordinateur et dispositif de commande par souris combines
US6703599B1 (en) 2002-01-30 2004-03-09 Microsoft Corporation Proximity sensor with adaptive threshold
WO2003073254A3 (fr) * 2002-02-28 2004-05-21 Koninkl Philips Electronics Nv Procede permettant d'obtenir un affichage pour interface graphique
US6879930B2 (en) 2001-03-30 2005-04-12 Microsoft Corporation Capacitance touch slider
US6954867B2 (en) 2002-07-26 2005-10-11 Microsoft Corporation Capacitive sensing employing a repeatable offset charge
WO2006119624A1 (fr) * 2005-05-10 2006-11-16 Tyco Electronics Canada Ltd. Dispositif d'entree capacitif avec touches virtuelles
GB2437827A (en) * 2006-05-05 2007-11-07 Harald Philipp Touch screen element
US7499806B2 (en) 2002-02-14 2009-03-03 Illumina, Inc. Image processing in microsphere arrays
EP1405298A4 (fr) * 2001-06-06 2009-04-29 Cirque Corp Systeme permettant de placer un pave tactile a detection de proximite en dessous du clavier numerique d'un telephone mobile
US7803537B2 (en) 2000-02-16 2010-09-28 Illumina, Inc. Parallel genotyping of multiple patient samples
US8305359B2 (en) 2003-08-05 2012-11-06 Synaptics Incorporated Capacitive sensing device for use in a keypad assembly
US8619054B2 (en) 2006-05-31 2013-12-31 Atmel Corporation Two dimensional position sensor
US8839154B2 (en) 2008-12-31 2014-09-16 Nokia Corporation Enhanced zooming functionality
CN110887745A (zh) * 2019-11-18 2020-03-17 宁波大学 基于投射式电容屏的大型岩体结构面剪切试验切向、法向位移的实时测量方法

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US5598527A (en) * 1992-11-12 1997-01-28 Sextant Avionique Compact and ergonomic communications terminal equipped with proximity detection surfaces

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US4736191A (en) * 1985-08-02 1988-04-05 Karl E. Matzke Touch activated control method and apparatus
US5598527A (en) * 1992-11-12 1997-01-28 Sextant Avionique Compact and ergonomic communications terminal equipped with proximity detection surfaces

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US6624804B2 (en) 1998-04-06 2003-09-23 Ethertouch Limited Of Brumby House Positioning a cursor on the display screen of a computer
WO1999052027A1 (fr) * 1998-04-06 1999-10-14 Hans Rudolf Sterling Positionnement du curseur sur l'ecran d'affichage d'un ordinateur
US7803537B2 (en) 2000-02-16 2010-09-28 Illumina, Inc. Parallel genotyping of multiple patient samples
US6924789B2 (en) 2000-10-03 2005-08-02 Nokia Corporation User interface device
EP1197835A3 (fr) * 2000-10-03 2003-02-05 Nokia Corporation Appareil d'interface utilisateur
GB2367530B (en) * 2000-10-03 2003-07-23 Nokia Mobile Phones Ltd User interface device
EP2273350A1 (fr) * 2000-10-03 2011-01-12 Nokia Corp. Appareil d'interface pour l'utilisateur
US7050927B2 (en) 2001-03-30 2006-05-23 Microsoft Corporation Capacitance touch slider
US7158125B2 (en) 2001-03-30 2007-01-02 Microsoft Corporation Capacitance touch slider
US7812825B2 (en) 2001-03-30 2010-10-12 Microsoft Corporation Capacitance touch slider
US6879930B2 (en) 2001-03-30 2005-04-12 Microsoft Corporation Capacitance touch slider
EP1405298A4 (fr) * 2001-06-06 2009-04-29 Cirque Corp Systeme permettant de placer un pave tactile a detection de proximite en dessous du clavier numerique d'un telephone mobile
US6611921B2 (en) 2001-09-07 2003-08-26 Microsoft Corporation Input device with two input signal generating means having a power state where one input means is powered down and the other input means is cycled between a powered up state and a powered down state
US6995747B2 (en) 2001-09-07 2006-02-07 Microsoft Corporation Capacitive sensing and data input device power management
US7023425B2 (en) 2001-09-07 2006-04-04 Microsoft Corporation Data input device power management including beacon state
US6661410B2 (en) 2001-09-07 2003-12-09 Microsoft Corporation Capacitive sensing and data input device power management
US6816150B2 (en) 2001-09-07 2004-11-09 Microsoft Corporation Data input device power management including beacon state
US6850229B2 (en) 2001-09-07 2005-02-01 Microsoft Corporation Capacitive sensing and data input device power management
WO2003050671A3 (fr) * 2001-12-11 2003-11-27 Wolfgang Fallot-Burghardt Clavier d'ordinateur et dispositif de commande par souris combines
US7002550B2 (en) 2002-01-30 2006-02-21 Microsoft Corporation Proximity sensor with adaptive threshold
US6933922B2 (en) 2002-01-30 2005-08-23 Microsoft Corporation Proximity sensor with adaptive threshold
US6703599B1 (en) 2002-01-30 2004-03-09 Microsoft Corporation Proximity sensor with adaptive threshold
US7479944B2 (en) 2002-01-30 2009-01-20 Microsoft Corporation Proximity sensor with adaptive threshold
US7499806B2 (en) 2002-02-14 2009-03-03 Illumina, Inc. Image processing in microsphere arrays
WO2003073254A3 (fr) * 2002-02-28 2004-05-21 Koninkl Philips Electronics Nv Procede permettant d'obtenir un affichage pour interface graphique
US7124312B2 (en) 2002-07-26 2006-10-17 Microsoft Corporation Capacitive sensing employing a repeatable offset charge
US6954867B2 (en) 2002-07-26 2005-10-11 Microsoft Corporation Capacitive sensing employing a repeatable offset charge
US8305359B2 (en) 2003-08-05 2012-11-06 Synaptics Incorporated Capacitive sensing device for use in a keypad assembly
WO2006119624A1 (fr) * 2005-05-10 2006-11-16 Tyco Electronics Canada Ltd. Dispositif d'entree capacitif avec touches virtuelles
GB2437827B (en) * 2006-05-05 2008-03-26 Harald Philipp Touch screen element
GB2437827A (en) * 2006-05-05 2007-11-07 Harald Philipp Touch screen element
US8648819B2 (en) 2006-05-05 2014-02-11 Atmel Corporation Touch screen element
US9430104B2 (en) 2006-05-05 2016-08-30 Atmel Corporation Touch screen element
US8619054B2 (en) 2006-05-31 2013-12-31 Atmel Corporation Two dimensional position sensor
US9927476B2 (en) 2006-05-31 2018-03-27 Atmel Corporation Two dimensional position sensor
US8839154B2 (en) 2008-12-31 2014-09-16 Nokia Corporation Enhanced zooming functionality
CN110887745A (zh) * 2019-11-18 2020-03-17 宁波大学 基于投射式电容屏的大型岩体结构面剪切试验切向、法向位移的实时测量方法

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