United States Patent [19]
`Greanias et al.
`
`[11]
`[45]
`
`Patent Number:
`Date of Patent:
`
`4,686,332
`Aug. 11, 1987
`
`[54] COMBINED FINGER TOUCH AND STYLUS
`DETECTION SYSTEM FOR USE ON THE 1
`VIEWING SURFACE OF A VISUAL DISPLAY
`DEVICE
`[75] Inventors: Evon C. Greanias, Chevy Chase,
`Md.; C. Richard Guarnieri, Somers,
`N.Y.; John J. Seeland, Jr., Oakland
`Park, Fla.; Guy F. Verrier, Reston,
`Va.; Robert L. Donaldson, Annapolis,
`Md.
`[73] Assignee: International Business Machines
`Corporation, Armonk, NY.
`[21] Appl. No.: 878,949
`[22] Filed:
`Jun. 26, 1986
`
`[51] Int. (14 ............................................ .. G08C 21/00
`[52] US. Cl. ................... .,
`. 178/19; 340/706
`[58] Field of Search ........................... .. 178/18, 19, 20;
`340/706, 709; 324/207
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`. _ .
`3,696,409 10/1332 Braiten
`3’757’322 9/1 3 Bar an at a‘ '
`3,992,597 11/1976 Hannula ...... ..
`
`3,999,012 12/1976 Dym . . . . . . . . . . . . . .
`
`4,009,338 2/1977 Lowy et a1‘
`
`. . .
`
`36c5
`/ 5
`200/6139
`
`. . . .. 178/18
`
`178/18
`
`4,582,955 4/1986 Blesser ................................ .. 178/19
`Primary Examiner-Sta?'ord D. Schreyer
`Attorney, Agent, or Firm—John E. Hoel
`[57]
`ABSTRACT
`A combined ?nger touch and stylus detection system is
`disclosed for use on the viewing surface of the visual
`display device. Transparent conductors arranged in
`horizontal and vertical grid are supported on a ?exible,
`transparent overlay membrane which is adaptable to a
`variety of displays. A unique interconnection pattern is
`provided between the transparent conductors in the
`array and buses which interconnect the conductors
`with the supporting electronics, whereby a minimum
`number of bus wires can be employed to service the
`array conductors and yet both unique ?nger touch loca
`tion sensing and unique stylus location sensing can be
`accomplished. The system includes a control processor
`which operates on stored program instructions which,
`in a ?rst embodiment provides for the alternate detec
`tion of either ?nger touch location or stylus location
`and, in a second embodiment, provides for the simulta
`neous detection of both ?nger touch location and stylus
`location. The resulting system provides the unique func
`tion of combined ?nger touch and stylus detection, is
`adaptable to a variety of display surfaces, is provided
`with a structure which is easily manufacturable, and
`.
`.
`.
`.
`which has an inherent long-term reliability.
`
`.
`
`..
`
`.
`
`.
`
`4,103,252 7/1978 Bobick . . . . . . . . . .
`
`. . . .. 331/48
`
`4,398,181 8/1983 Yamamoto .................... .. 340/365 S
`
`10 Claims, 25 Drawing Figures
`
`DETECTION SYSTEM
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`

`

`US. Patent Aug. 11,1987
`
`Sheetl 0117
`
`4,686,332
`
`F761 2. SEC
`2-2‘
`
`2
`
`

`

`U. S. Patent Aug. 11, 1987
`
`Sheet2 of 17
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`

`U. S. Patent Aug. 11,1987
`
`Sheet3 0f17
`
`4,686,332
`
`FIG 4.
`USING THE WIRE PAIR CONCEPT. THERE ARE THREE MEASUREMENTS THAT ARE
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`
`4
`
`

`

`U. S. Patent Aug. 11,1987
`
`Sheet4of17
`
`4,686,332
`
`FIG: 6.
`THE NEXT DATA, PI, IS FORMED BY SHIFTING THE PREVIOUS P0 PLOT To THE
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`
`

`

`US. Patent Aug. 11,1987
`
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`U. S. Patent Aug. 11,1987
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`U. S. Patent Aug. 11, 1987
`
`Sheet9 0m 4,686,332
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`US. Patent Aug. 11,1987
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`U. S. Patent Aug. 11,1937
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`U. S. Patent Aug. 11,1987
`
`Sheetl3 ofl7 4,686,332
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`

`US. Patent Aug. 11,1987
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`Sheet 14 0f17 4,686,332
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`

`U. S. Patent Aug. 11, 1987
`
`Sheet 15 of17 4,686,332
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`U. S. Patent Aug, 11, 1987
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`

`U. S. Patent Aug. 11,1987
`
`Sheet 17 0117 4,686,332
`
`F161 /.9.
`DISPLAY AS SEEN
`THROUGH OVERLAY
`SHOWING SIMULTANEOUS
`FINGER TOUCH
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`

`

`1
`
`COMBINED FINGER TOUCH AND STYLUS
`DETECTION SYSTEM FOR USE ON THE
`VIEWING SURFACE OF A VISUAL DISPLAY
`DEVICE
`
`0
`
`4,686,332
`2
`which is electromagnetically radiated from the surface
`of the tablet and which is received by a pickup stylus
`connected to a signal detector. In one type of opaque
`graphics tablet, a ?eld gradient is imposed from one side
`to the other side of the tablet and the strength of the
`?eld as picked up by the stylus, is correlated with the
`position attributed to the stylus. Another approach has
`been described by H. Dym, et al. in US. Pat. Nos.
`3,992,579; 3,999,012; and 4,009,338, those patents being
`assigned to the IBM Corporation. Dym, et al. describe
`driving the conductors embedded in the opaque graph
`ics tablets so that they are selectively energized with 40
`kilohertz signals in a multiple stage operation to ?rst
`determine the stylus proximity to the surface of the
`tablet and then to track the position of the stylus along
`the surface of the tablet in the horizontal and vertical
`directions. During the proximity stage of operation, the
`conductors in all regions of the tablet surface emit sig
`nals which are detected by the stylus as it approaches
`the surface. When the amplitude of the received signals
`is great enough, the operation then changes into the
`locate and tracking mode which is programmed to pro
`duce periodic indications of the stylus position with
`respect to the horizontal and vertical conductors em
`bedded in the tablet.
`The popularity of the Personal Computer can be
`attributed, in part, to the enhanced productivity which
`can be achieved by applying data processing techniques
`to the execution of tasks which were previously done
`manually. Typical applications employing an interac
`tive input at the display surface of the monitor in a
`Personal Computer, require the operator to make con
`trol selections at the keyboard, perhaps selecting the
`mode of operation or particular image to be displayed,
`prior to using the interactive input device for inputting
`data to the system. For example, in hotel management
`applications, the operator would enter control informa
`tion at the keyboard to select either a ?rst displayed
`image for a room assignment application or a second
`displayed image for entering billing information. Only
`after having made the control input at the keyboard,
`will the operator be able to make data entries by means
`of the interactive input at the display surface.
`
`BACKGROUND OF THE INVENTION
`1. Technical Field
`The invention disclosed broadly relates to data pro
`cessing technology and more particularly relates to
`input devices for use in conjunction with visual dis
`plays.
`2. Background Art
`In data processing systems, a central processor exe
`cutes a sequence of stored program instructions to pro
`cess data provided by an input device and to present the
`results of the data processing operations to an output
`device. Data processing results can be presented in
`either alphanumeric text or in graphical form and a
`universal mechanism for manifesting those results is by
`means of a visual display device such as a cathode ray
`tube monitor, a gas panel display, an array of light emit
`ting diodes, or other types of visual display devices.
`Frequently, the results presented to the user on a visual
`display device, will require the user to provide addi
`tional data to the data processing system. Various types
`of data input devices have been employed in data pro
`cessing systems, for example keyboard input, graphical
`tablet input, and various forms of display surface inputs.
`Human factors studies have shown that by providing a
`means for inputting data on the visual display screen
`itself, the user can achieve the most closely coupled
`interactive operations with the data processing system.
`When the user responds to visual signals output at the
`face of the visual display device, by inputting signals at
`that same visual display surface, an accuracy and imme
`diacy in the interaction between man and machine can
`be achieved. This form of input device is easy to learn to
`use and seems the most natural and user-friendly to the
`operator
`Various types of interactive input devices for use at
`the display surface have been provided in the prior art.
`One of the ?rst forms of interactive devices was the
`light pen, which is an optical detector provided in a
`hand-held pen, which is placed against the display sur
`face of a cathode ray tube screen. When the dot of light
`represented by the scanning raster is detected by the
`light pen, the coordinates of the raster dot are attributed
`as the location of the hand-held pen. Another type of
`interactive input device for use on a display surface is
`the mechanical deformation membrane, which is a
`transparent laminate placed over the display surface.
`The laminate consists of two conductor planes respec
`tively deposited on a ?exible medium so that when the
`user mechanically displaces one of the conductor planes
`by a ?nger touch, the conductors are brought into elec
`trical contact with the conductors in the second plane.
`The electrical resistance of the conductor plane is
`changed as a function of the position of the ?nger touch
`on the membrane and appropriate electronics are pro
`vided to translate that resistance value into the position
`attributed to the ?nger touch.
`Opaque graphics tablets, upon which a sheet of draw
`ing paper can be supported for tracing with an elec
`tronic stylus, have been provided in the prior art. In
`opaque graphics tablets, a horizontal wire grid and a
`vertical wire grid are embedded in the surface of the
`tablet. The wires in the tablet are driven with a signal
`
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`OBJECTS OF THE INVENTION
`It is therefore an object of the invention to provide an
`improved interactive input device for a display surface.
`It is another object of the invention to provide an
`interactive input device which permits either ?nger
`touch input or stylus detection input modes.
`It is yet a further object of the invention to provide an
`improved interactive input for a display surface which
`can be adapted to a variety of surface contours.
`It is yet a further object of the invention to provide an
`improved interactive input for a display surface which
`is reliable and is inexpensive to manufacture.
`It is yet a further object of the invention to provide an
`interactive input device for use at a display surface,
`which permits the simultaneous detection of both a
`?nger touch and a stylus position.
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`DISCLOSURE OF THE INVENTION
`A combined ?nger touch and stylus detection system
`is disclosed for use on the viewing surface of a visual
`display device. The system includes an array of hori
`zontal and vertical conductors arranged on the viewing
`surface of the visual display device, having an I/O ter
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`FIG. 4 is a schematic view of the overlay for stylus
`minal coupled thereto, for conducting electrical signals
`detection.
`between the terminal and the vicinity of the viewing
`FIG. 5 illustrates the radiative signal amplitude for
`surface. A radiative pickup stylus is also included, hav
`measuring pair P0 in stylus detection.
`ing an output terminal, for receiving electromagnetic
`FIG. 6 shows the measurement for the pair P1 for
`signals radiated from the array.
`stylus detection.
`The system includes a selection means having a
`FIG. 7 shows the measurement for the pair P2 for
`switchable path connected to the I/O terminal of the
`stylus detection.
`array and having a control input, for connecting se
`FIG. 8 is a cross-sectional view of the overlay 20 and
`lected patterns of a plurality of the horizontal and verti
`the ?nger 70 for ?nger touch detection.
`cal conductors to the switchable path in response to
`FIG. 9 is an architectural diagram of the detection
`control signals applied to the control input. A capaci
`system.
`tance measuring means is also included, having an input
`FIG. 10 is a flow diagram of the operation of the ?rst
`coupled to the switchable path of the selection means,
`embodiment of the invention for detecting either ?nger
`for measuring the capacitance of selected ones of the
`touch or stylus position.
`conductors in the array, in response to the control sig
`FIG. 11 is a rear view of the general layout of the
`nals applied to the control input.
`overlay 20.
`The system further includes a radiative signal source
`FIG. 12 is a side cross-sectional view of the overlay
`having an output coupled to the switchable path of the
`20 along the section line 12—12’ of FIG. 11, showing
`selection means, for driving selected ones of the con
`the detail of the display input area.
`ductors in the array, in response to the control signals
`FIG. 13 is a front breakaway view of the overlay 20
`applied to the control input. A radiative signal measur
`in the bus region.
`ing means is also included, coupled to the radiative
`pickup stylus, for measuring the electromagnetic signals
`FIG. 14 is a side cross-sectional view along the sec
`tion line 14—14' of FIG. 13.
`received by the stylus.
`FIGS. 15A; 15B; 15C are a front view of the layout of
`In addition, the system includes a control processor
`the X bus for the overlay 20.
`connected to the control input of the selection means,
`FIGS. 16A, B, & C are a flow diagram of a second
`for executing a sequence of stored program instructions
`embodiment of the invention, when both ?nger touch
`to sequentially output the control signals to the selec
`and stylus detection can be simultaneously carried out.
`tion means. The control processor is connected to the
`FIG. 17 is a timing diagram for the second embodi
`capacitance measuring means, for receiving measured
`ment of the invention, for the simultaneous detection of
`-, capacitance values of the conductors when the selection
`both ?nger touch and stylus location.
`; means, in response to the control signals, has connected
`FIG. 18 is a diagram of the memory organization for
`a ?rst pattern of a plurality of the conductors in the
`the RAM 102 in the second embodiment of the inven
`array to the capacitance measuring means, to detect the
`tion.
`location of a ?nger touch with respect to the viewing
`FIG. 19 is a front view of the display as seen through
`surface of the display device. The control processor is
`the overlay 20, showing the simultaneous ?nger touch
`also connected to the radiative signal measuring means,
`and stylus detection, in accordance with the second
`' for receiving measured radiative signal values when the
`embodiment of the invention.
`‘ selection means, in response to the control signals, has
`connected a second pattern of a plurality of the conduc
`tors in the array to the radiative signal source, to detect
`the location of the stylus with respect to the viewing
`surface of the display device.
`In this manner, both ?nger touch location and stylus
`location with respect to the viewing surface of the dis
`play, can be detected.
`The system can be used for both sequential and simul
`taneous detection of finger touch and stylus position.
`The system makes use of a unique interconnection ar
`rangement for the horizontal and vertical conductors to
`respective buses which are of a reduced size, thereby
`saving space and driver electronics. A unique overlay
`membrane structure supports the horizontal and verti
`cal conductors of the array and has suf?cient mechani
`cal ?exibility to enable it to conform to the surface
`contour, of a variety of display surfaces.
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`BRIEF DESCRIPTION OF THE DRAWINGS
`The foregoing and other advantages of the invention
`will be more fully, understood with reference to the
`description of the best mode and the drawing wherein:
`FIG. 1 is a front view of the overlay 20 and the
`mounting frame 22.
`FIG. 2 is a side cross-sectional, breakaway view of
`the overlay and mounting frame of FIG. 1, along with
`65
`section line 2—2’.
`FIG. 3 is a side view of the overlay 20 and the stylus
`60 for stylus detection.
`
`DESCRIPTION OF THE BEST MODE FOR
`CARRYING OUT THE INVENTION
`The combined ?nger touch and stylus detection sys
`tem is shown in a front view in FIG. 1 and in a side
`cross-sectional view in FIG. 2, in association with a
`cathode ray tube display. The overlay 20 consists of
`two sheets of durable, transparent plastic, with an array
`of horizontal transparent conductors embedded in the
`?rst sheet and an array of vertical transparent conduc
`tors embedded in the second sheet. The overlay 20 can
`be mounted by means of the frame 22 onto the display
`surface 32 of the cathode ray tube 24. The mounting
`frame 22 consists of a base portion 28 which attaches to
`the sidewall 26 of the cathode ray tube (CRT) 24. The
`front facing surface 30 of the base portion 28 can have
`a curvature substantially the same as the curvature of
`the display surface 32. The overlay 20 is mechanically
`?exible and can be laid directly upon the surface 32 of
`the CRT so that its edges overlap the surface 30 of the
`base portion 28 for the mounting frame 22. The clamp
`ing member 34 can then be placed over the edges of the
`overlay 20 so that the mating surface 38, which has a
`curvature similar to that of the surface 30, clamps the
`edges of the overlay 20. The mounting bolts 36 secure
`the member 34 to the base portion 28.
`FIG. 2 shows a cross-sectional view of the overlay 20
`positioned on the display surface 32 of the CRT. The
`overlay is stretched slightly by the mounting frame, to
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`provide a smooth, tight and well supported surface for
`finger touch and stylus detection. The overlay shown in
`FIG. 3 consists of the inner substrate 50 which is a sheet
`of polyethylene terephthalate which is
`transparent,
`electrically insulative, and has a thickness of approxi-
`mately 0.002 inches. An array of horizontal transparent
`conductors is deposited on the surface of the inner sub-
`strate 50 and are designated as Y1, Y2, Y3, etc., with the
`Y3 wire being shown in FIG. 3. The transparent con-
`ductors can be composed of indium tin oxide, for exam—
`ple, which is a well-known transparent conductor mate-
`rial. The thickness of the transparent conductor can be
`approximately 1000 angstroms. The conductors are
`approximately 0.025 inches wide and are spaced ap-
`proximately 0.125 inches on a center-to-center spacing.
`An insulation layer 52 covers the horizontal Y wires
`and can be composed of a transparent adhesive such as
`ultraviolet
`initiated vinyl acrylic polymer having a
`thickness of approximately 0.002 inches. The upper
`portion of the overlay 20 shown in FIG. 3 consists of
`the outer substrate 54 which is a sheet of polyethylene
`terephthalate which is optically transparent, electrically
`insulative and has a thickness of approximately 0.002
`inches. Deposited on the surface of the outer substrate
`54 is a vertical array of transparent conductors desig-
`nated X1, X2, X3 .
`.
`. X6 .
`.
`.
`. The conductors X1, etc.
`are also composed of indium tin oxide and have a thick-
`ness of approximately 1000 angstroms, a width of ap-
`proximately 0.025 inches and a spacing of approxi-
`mately 0.125 inches, center-to«center. The outer sub—
`strate 54 and the vertical conductors X are joined by the
`adhesive insulation layer 52 to the inner substrate 50 and
`the horizontal wires Y. The X and the Y transparent
`conductors can also be composed of gold and silver or
`other suitable materials. The thickness of the conduc-
`tors is adjusted to provide resistance below 50 ohms per
`square and an optical transmission which is greater than
`80 percent.
`FIG. 3 depicts the arrangement for detection of the
`stylus 60 when it is closer than the locate threshold
`distance 62. The principle of operation in the stylus
`detection mode is that the X and/or Y conductors are
`driven by a 40 kilohertz oscillator driver so that the X
`and/or Y conductors act as a transmitter of electromag-
`netic radiation and the stylus 60 acts as a receiver of that
`radiation. To transmit a signal, the oscillator selectively
`drives either the X conductors or the Y conductors.
`The stylus 60 detects the signal and electronics con-
`nected to the stylus digitizes the magnitude of the sig-
`nal. The magnitude of the signal detected by the stylus
`is a function of the height of the stylus above the over-
`lay 20. By comparing this magnitude to known thresh-
`olds, the height of the stylus above the overlay can be
`determined. When the stylus signal has reached the
`contact threshold corresponding to the locate threshold
`distance 62, the operation of stylus detection can shift
`from proximity detection to a location and tracking
`mode. The object of tracking the stylus is to have the X
`conductors and the Y conductors in the overlay driven
`in such a manner that the radiation picked up by the
`stylus 60 can enable the attribution of an instantaneous
`position for the stylus.
`The basic drive pattern for determining the stylus
`position is schematically shown in FIG. 4. A wire pair
`is defined as two adjacent X conductors, for example,
`with the left-hand conductor and several conductors to
`the left thereof being either grounded or connected to a
`first reference potential and the right-hand conductor
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`and several conductors to the right thereof being driven
`by the oscillator driver. FIG. 4 shows the wire pair P0
`located beneath the stylus 60, with the conductor X3
`being the left-handed conductor and the conductor X4
`being the right-handed conductor. The conductors X1,
`X2 and X3 are connected to ground potential whereas
`the conductors X4, X5 and X6 are connected to the
`oscillator driver. FIG. 5 shows the amplitude of the
`signal received by the stylus 60 as it would pass from
`left to right from above the conductor X1 to a position
`above the conductor X6. Note that within and around
`the wire pair X3 and X4, the stylus signal varies linearly
`with position. This linearity is the basis for an accurate
`interpolation technique for providing a precise measure
`of the position of the stylus 60 based upon the measure—
`ment of radiation from three wire pairs. The first stage
`in the measurement is measuring the amplitude for the
`wire pair P0. FIG. 6 shows the second stage in the
`measurement where the wire pair P1 is formed with the
`conductors X4 and X5. The plot of the magnitude of the
`signal received by the stylus 60 which remains fixed at
`its location shown in FIGS. 4 and 5, would indicate a
`lower relative measured amplitude for the wire pair P1
`measurement. The final data in the three stage operation
`of locating the position of the stylus 60 is shown in FIG.
`7, where the wire pair P2 is the inverse of the wire pair
`P0. That is, the conductors X1, X2 and X3 are driven
`with the oscillator driver, whereas the conductors X4,
`X5 and X6 are connected to ground or reference poten-
`tial. The signal amplitude is shown for the wire pair P2
`in FIG. 7. Once again, with the stylus 60 remaining in
`the same position that it had for FIGS. 4, 5 and 6, the
`magnitude of this signal for the wire pair P2 will be
`measured.
`The calculation of the horizontal position of the sty-
`lus 60 with respect to the vertical X conductors X1, X2,
`X3, etc. is done in two stages. First, the base coordinate
`is calculated and then second an offset coordinate is
`calculated which is added to the base coordinate to
`form the resultant measured position. To calculate the
`base coordinate, the system calculates the number of
`wires between the origin of coordinates at the left-hand
`edge of the overlay and the first wire adjacent to the
`axis of the stylus 60. This number of wires is multiplied
`times the pitch of the X conductor separation, in this
`case 0.125 inches, to obtain the base coordinate value.
`The base coordinate produced is the midpoint between
`the wire pair X3 and X4 in this example.
`The offset coordinate is the coordinate of the stylus
`relative to the midpoint of the wire pair X3 and X4. The
`offset coordinate is equal to the wire separation pitch in
`the horizontal direction times (PO-P2) divided by
`2x(P0-P1). The numerator of this expression is a linear
`expression within a wire pair whereas the denominator
`is a constant. Both of these terms depend upon the angle
`of the stylus with respect to the tablet which can vary
`during normal operation. The division operation can-
`cels this dependence, allowing the expression to be
`invariant as to the angle at which the stylus is held. The
`resulting ratio varies linearly between approximately
`-—1 and +1 and, when multiplied times the pitch, gives
`an additive factor which, when added to the base coor-
`dinate, results in the interpolated value for the horizon-
`tal position of the stylus with respect to the vertical X
`conductors. The resolution for this measurement
`is
`typically 0.01 inches. A similar operation is conducted
`for the horizontal conductors Y1, Y2, etc. to establish
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`4,686,332
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`constitutes a unique combination which is never dupli-
`cated elsewhere on the array. One of the problems
`solved by the invention disclosed herein is how to com—
`bine both finger touch detection and stylus location
`detection using the same array of horizontal and verti-
`cal conductors connected through their
`respective
`drive buses.
`‘
`FIG. 11 is a rear View over the overlay 20 showing
`the general layout of the overlay. The X bus 80 consists
`of 16 drive wires 1, 2, .
`.
`. l6 and similarly the Y bus 90
`consists of 16 bus wires. The X bus 80 is connected
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`7
`the vertical position of the stylus with respect to the
`horizontal conductors.
`It is seen that in order to locate position of the stylus
`with respect to the vertical conductors,
`the vertical
`conductors must be arranged with each conductor in
`any group of at least six adjacent conductors, uniquely
`connected to the oscillator driver. A similar condition
`must also prevail for the horizontal Y conductors. As
`was previously mentioned, in order to obtain an approx-
`imately 0.01 inch resolution, a grid pitch of approxi-
`mately 0.125 inches must be maintained for the conduc-
`tors in both the horizontal direction and in the vertical
`direction. If a display area of 12—13 inches in the hori-
`zontal and the vertical direction is to be covered by the
`overlay, then approximately 100 vertical X conductors
`and 100 horizontal Y conductors will be required in the
`overlay 20. If 200 different drivers were required to
`drive all 200 conductors, the mechanical and electrical
`complexity necessary to make that connection would be
`prohibitive. It is clearly advantageous to provide some
`means for reducing the number of driver wires which
`interconnect the conductor wires in the array to the
`oscillator driver. Dym, et al. have provided in their
`above cited patents, a busing technique which employs
`a horizontal bus having 24 separate driver wires each of
`which are respectively connected to several vertical
`conductors in the opaque graphics tablet disclosed
`therein. The horizontal conductors are similarly ar-
`. ranged and are connected through a vertical bus also
`,» .having 24 wires. Taking the vertical array conductors
`-