US3624619A - Pressure-sensing tablet - Google Patents

Pressure-sensing tablet Download PDF

Info

Publication number
US3624619A
US3624619A US792118*A US3624619DA US3624619A US 3624619 A US3624619 A US 3624619A US 3624619D A US3624619D A US 3624619DA US 3624619 A US3624619 A US 3624619A
Authority
US
United States
Prior art keywords
sheet
tablet
sheets
tablet according
conductive
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US792118*A
Inventor
Biagio F Ambrosio
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telautograph Corp
Original Assignee
Telautograph Corp
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 Telautograph Corp filed Critical Telautograph Corp
Application granted granted Critical
Publication of US3624619A publication Critical patent/US3624619A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00Input 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
    • G06F3/01Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/045Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Definitions

  • the perforations are spaced in a uniform pattern and are of a diameter sufficient to permit the writing point under normal writing pressure to deform said first sheet into contact with said second sheet.
  • the perforations are formed by disposing the elastoner sheet in front of a laser and pulsing the laser to form a repeating line pattern of uniformly spaced and sized perforations.
  • the present invention relates to a graphic input device and, more particularly to a free-pen pressure-sensing tablet.
  • the most familiar device for onlline graphic input is the light pen which consists of on-line photosensor which produces an electric output when it senses a spot displayed on a computer-controlled cathode-ray tube.
  • material cannot be traced from hard copy and there is not hard copy input.
  • a number of relatively simple devices employ a mechanical linkage between a stylus and an analog or digital encoding transducer or potentiometer.
  • the disadvantages of the coupled devices are the restrictions of the mechanical linkage, its basic analog nature and the unnaturalness of the use of a linked pen.
  • the Rand tablet closer matches mans existing dexterity with a penlike instrument on a horizontal surface and does not require hand-directed creation of information on a surface coincidental with a display device, such as in the light pen.
  • the Rand tablet requires capacitive coupling through the stylus, and the tablets are very expensive, even in small sizes, due to the intricate complexity of the stylus following electronics.
  • Pressure-Sensing analog and digital sheet encoder tablets have been suggested but have not been adopted since the accuracy and resolution have been low, and the mechanical properties poor and failure and cost of the tablets have been potentially high.
  • a further object of the invention is the provision of a pressure-sensing encoder that is not sensitive to forces applied to the face of the tablet encoder from large objects but is sensitive to the forces applied to the tablet from the writing point of a pen, pencil or stylus.
  • Another object of the invention is the provision of a freepen writing tablet that directly converts movement of a pen, pencil or stylus over a platen or paper into electrical signals, the magnitude of which is proportional to the position of the writing instrument on the platen or paper.
  • the pressure-sensing encoder tablet in accordance with the invention detects the movement of an electrically and mechanically uncoupled pointed writing instrument over the surface thereof.
  • the tablet comprises a first deformable sheet having an electrically conductive surface, a second sheet having an electrically conductive surface and a resilient insulator sheet disposed between the conductive surfaces of said first and second sheets.
  • the resilient sheet contains a uniform pattern of writing instrument point receiving perforations.
  • the first and second sheets preferably comprise a thin sheet of deformable organic synthetic resin, such as Mylar (a polyester), having coated thereon a thin layer of metal, such as copper, silver, gold or aluminum, which may be in the form of a continuous film or in a grid of thin spaced parallel conductive lines.
  • the assembly of deformable sheets is preferably supported on a rigid platen, such as a sheet of glass.
  • the resilient insulator sheet serves to electrically insulate the first and second conductive sheets during normal unstressed conditions.
  • the perforations which are from about 2 to 8 mils in diameter and are separated by about 1 to 3 mils, permit the point of the writing instrument to deform the top sheet into said perforation to a sufiicient depth to make contact between the conductive surfaces of said first and second sheets.
  • the resilient insulator sheet has sufficient compressibility to avoid contact between the sheets when the hand of the writer presses on the surface of the top sheet or when the pen or other light implement is laid on the surface of the tablet.
  • the resilient insulator sheet is preferably a diene elastomer, such as natural rubber, or a synthetic butadiene copolymer, such as SBR having a thickness of l to 3 mils and a compressive strength about 5 pounds per square inch, preferably about 20 pounds per square inch, and a Shore Hardness of from 30 to 40 percent.
  • the tablet can further include means for impressing an electrical signal on said first sheet and means connected to said first and second sheets for detecting the value of said signal to provide a signal indicative of the location of the writing instrument point wherever it makes contact between said sheets.
  • FIG. I is a schematic illustration of a single-coordinate, free-pen, encoding tablet
  • FIG. 2 is a cross-sectional view of the tablet of FIG. 1 shown with a ball-pen point applied to a sheet of paper;
  • FIG. 3 is a block and schematic diagram of a system for forming a resilient, perforated insulator sheet according to the invention
  • FIG. 4 is a cross-sectional view of one form of tablet designed to detect by pressure the X and Y coordinates of the writing point;
  • FIG. 5 is a schematic view of a digital tablet
  • FIG. 6 is a cross-sectional view of the tablet of FIG. 5:
  • FIG. 7 is an enlarged view of an intersection of the grid lines of the tablet of FIG. 5;
  • FIG. 8 is a further view of the tablet of FIG. 5 showing a point contact of the grid lines induced by pressure of a ballpen point.
  • the tablet 10 includes a thin resistive top sheet 12 and a conductive bottom sheet 14 separated by a resiliently deformable perforated elastomer sheet 16.
  • the perforations 17 are arranged in a repeating line pattern and are of a diameter sufficient to accept the deformation produced in the top sheet 12 by means of a writing instrument point 18 to a sufficient depth to make contact during deformation between the top and bottom sheets 12 and 14.
  • the top sheet 12 is formed of a thin conductive film, such as copper, and electrode busses 20 of a highly conductive metal, such as silver or gold, are provided along each edge of the sheet.
  • a source of potential 19 is connected to the busses 20 and applied across the top sheet 12. Pressure from the writing point 18 of the writing instrument onto a sheet of paper 21, forces the paper sheet, and top sheet 12 into the perforation 17 and makes contact between sheets 12 and 14 at a given point 25 inducing an analog voltage signal detected at the edge 24 of sheet 14, the signal value being proportional to the X-coordinate of the point contact location.
  • the thin metallic films are preferably supported on thin deformable insulative organic resin plastic substrates such as polyethylene or a polyester, for example, Mylar.
  • the substrate and films are of minimum thickness compatible with the desired mechanical properties of the final tablet, and suitably,
  • the substrate and metal film are each from below l to 3 mils in thickness.
  • the top sheet may contain a continuous metallic film or may contain a series of parallel separated lines forming a grid. The spacing of the lines is selected to provide coordinate detection signals compatible with acceptable line resolution for-the desired application and is usually from 30 lines per inch to 200 lines per inch.
  • the size of the tablet is determined by the application. It can be typical letter size of 8% inches by l l inches or can be of smaller dimensions to accommodate business forms as in conventional telewriter instruments or of larger size for use in on-line date processing as a graphic input to a man-computer interface system.
  • the tablet of the invention is intended to permit completely natural manipulation of the penlike writing instrument.
  • the edge of the palm rests on the tablet surface and distributes the weight of the arm to the surface.
  • the fingers and wrist then apply sufficient pressure to the pen point to mark a sheet of paper and to simultaneously bring the conductive surfaces together at the contact point to develop a marking signal.
  • the resilient perforated elastomer sheet has a compressive strength sufficient to resist the pressure applied by the weight of the hand, suitably above p.s.i and preferably about p.s.i., but deforms to permit contact of the conductive sheets through the perforations when a pen point is applied.
  • a ball pen point is typically about to 40 mils in diameter. Writing force sufficient to provide a permanent copy of paper and to deform the underlying tablet of about 0.5 to 3 pounds will distribute about at least 10' psi. to the tablet through the point.
  • the thickness of the resilient sheet is maintained as low as possible consistent with maintaining separation of the sheets under normal hand pressure and is preferably from 1 to 3 mils in thickness.
  • An elastomer such as SBR rubber having a Shore Hardness of 30-40 will provide sufficient compressive resistance to normal hand forces and will deform under theforce of a writing point.
  • the perforations are of a diameter to accept under writing point pressure the deformed top conductive film and, its backing and paper, if present, to a sufficient depth to provide contact with the sheets.
  • the perforations are suitably about 4 to 6 mils and for a 40 mil point about 6 to 8 mils.
  • the perforations are spaced to provide a resolution of 30 to 200 lines per inch.
  • the perforations are spaced over the grid lines and the grid line thickness is selected to provide a wide base sized perforations could not be provided.
  • a rubber is conveniently and accurately perforated by applying a laser beam collimated to the desired diameter to the sheet and scanning the sheet with the laser and pulsing the laser at the center of each perforation location.
  • a laser 30 pulsed by power source 32 to form a beam collimated by lens 31 onto a sheet 36.
  • the laser 30 is incrementally driven by scan drive 34 across a sheet 36 of elastomer.
  • the power source 32 pulses the laser 30 at each perforation location corresponding to an increment of the scan drive movement.
  • the scan drive returns to the opposite edge of the sheet and the drive rolls 38 advance the sheet one increment to the succeeding line.
  • one form of an analog tablet encoder includes a rigid glass platen 40 having a thin conductive film 42 applied to the surface thereof.
  • the film 42 is separated from a thin resistive film 44 by a perforated, insulator elastomer sheet 46.
  • the resistive film 44 is applied to a deformable Mylar sheet 48 which car' ries a second resistive film 50 on the top surface thereof.
  • the second film 50 is covered with a second perforated elastomer sheet 52 which is turn is covered with a conductive film 54 supported on a Mylar sheet 56, the top surface 58 of which receives a writing point directly or indirectly through a sheet of paper 60 placed on the top surface thereof.
  • An X-axis voltage source 66 is applied to the top and bottom of second resistive film 50 and X-axis analog voltage is detected from the edge of conductive film 54.
  • a second Y-axis voltage source 64 is applied across resistive film 44, and an X- axis analog voltage output is derived from the edge of conductive film 42.
  • Variations of the analog sheet encoder can readily be provided to follow the movement of the writing instrument. Phase detection or frequency difference techniques can be utilized to produce X and Y signals indicative of the location of the contact point.
  • the analog systems have an inherently low accuracy due to electrical or mechanical interference and analog drift.
  • FIGS. 5 and 6 a simplified digital system is illustrated comprising a rigid glass platen 70 on which is printed an X-line grid 72. For purposes of simplification, only 5 lines of the grid are illustrated.
  • a perforated resilient elastomer sheet 74 is interposed between the grid 72 and an X-grid 76 supported on a top Mylar sheet 78 which forms the surface of the tablet.
  • Each one 80 of the X-grid 76 is connected to resistors 82 R,R which are of different incremental values such as l, 2, 4, 8 and 16 ohms.
  • the resistors R,--R are imprinted onto the bottom surface of the Mylar sheet 78 and are connected to a thin film forming a bus 86 along one edge of the sheet.
  • the X- grid lines 80 are connected to a second bus 90 along the second edge of the sheet.
  • a voltage source 92 is connected to busses 86 and 90.
  • FIG. 7 an enlarged section of a l00-lpi tablet is disclosed.
  • the X- and Y-lines 80 and 81 are each 2 mils in width and are separated by 8 mils.
  • the perforation 96 through each sheet is 8 mils in diameter and the perforations disposed on 10 mil centers and, therefore, a 2 mil section of rubber remains between each perforation.
  • a 40 mil pen point 98 when applied to the top surface of Mylar sheet 78 will make point contact between X and Y-lines 80 and 81 at the intersection 91 thereof.
  • the pressure-sensing encoder tablet of this invention can be utilized to sketch, edit, compose or trace straight or curvilinear data.
  • lt can be utilized in telewriter transmitters or as a graphic input to a computer controlled cathode-ray tube display.
  • the display control can multiplex the pen position information with computer-generated information so the the CRT displays a composite of the pen position and the computer.
  • the horizontal surface and use of pen or pencil offers complete naturalness to the user.
  • a pressure-sensing encoder tablet for detecting the movement of a pointed writing instrument over the surface thereof comprising in combination:
  • a first sheet comprising a deformable of synthetic organic resin having a thin electrically conductive layer of metal coated on one surface thereof;
  • a resilient, deformable insulating sheet consisting essentially of a diene elastomer having a thickness of from i to 3 mils and a compression strength sufficient to withstand at least psi. without permitting contact of the conductive surfaces of said first and second sheets disposed between the conductive surfaces of said first and second sheets; said insulating sheet containing a uniform pattern of writing point receiving perforations having substantially the same diameter of between 2 to 8 mils and substantially the same separation between perforations of from 1 to 3 mils; and
  • a tablet according to claim 1 further including means for impressing an electrical signal on said first sheet and means connected to said first and second sheet for detecting the value of said signal.
  • said conductive layer is in the form of a grid comprising a series of spaced, parallel conductive lines of metal.
  • a tablet according to claim 8 further including a differently valued resistor connected to each of said lines.
  • a tablet according to claim 9 further including means for impressing a voltage on said lines and means connected to said first and second sheets for detecting the voltage drop through each of said lines.
  • a tablet according to claim 11 in which said sheet is perforated by vaporization of sheet material by a laser beam collimated to the diameter of the perforation.

Abstract

A pressure-sensing encoder tablet which detects the movement of a pointed writing instrument is disclosed. The tablet includes a resilient, perforated insulating elastoner sheet disposed between the conductive surfaces of first and second incoder sheets. The perforations are spaced in a uniform pattern and are of a diameter sufficient to permit the writing point under normal writing pressure to deform said first sheet into contact with said second sheet. The perforations are formed by disposing the elastoner sheet in front of a laser and pulsing the laser to form a repeating line pattern of uniformly spaced and sized perforations.

Description

United States Patent inventor Biagio F. Ambrosio Woodland Hills, Calif.
Appl. No. 792,118
Filed Jan. 17, 1969 Patented Nov. 30, 1971 Assignee Telautograph Corporation Los Angeles, Calif.
PRESSURE-SENSING TABLET 12 Claims, 8 Drawing Figs.
JIWII'I'IIIQTFJ I 11/1111.
TIIIIIIIIII III'IIIIIIII [56] References Cited UNITED STATES PATENTS 3,005,050 10/1961 Koenig, Jr. 178/20 3,308,253 3/1967 Krakinowski 178/18 Primary Examiner-Stanley M. Urynowicz, Jr. Attorneys-Samuel Lindenberg and Arthur F reilich ABSTRACT: A pressure-sensing encoder tablet which detects the movement of a pointed writing instrument is disclosed. The tablet includes a resilient, perforated insulating elastoner sheet disposed between the conductive surfaces of first and second incoder sheets. The perforations are spaced in a uniform pattern and are of a diameter sufficient to permit the writing point under normal writing pressure to deform said first sheet into contact with said second sheet. The perforations are formed by disposing the elastoner sheet in front of a laser and pulsing the laser to form a repeating line pattern of uniformly spaced and sized perforations.
PATENTED W30 l9?! SHEET 1 BF 2 POWER SOURCE J" OUTPUT IN VIZN'I'OR. BIAGIO E AMBROSIO AT TORNE YS.
PATENTED uuvao l97| SHEET 2 [IF 2 FIG. 5
FIG. 7
INVUN'I'UR.
B'AGIQ E AMBRQSIO BY M FIG.8
AT TORNEYS.
PRESSURE-SENSING TABLET BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphic input device and, more particularly to a free-pen pressure-sensing tablet.
2. Description of the Prior Art The available man-machine graphical communication devices provide far from optimum communication, considerably reducing the capabilities of either the machine or the user. To be fully effective, the devices must be natural and simple to operate, and be readily related to more conventional design tools, such as pencil or pen and paper.
The most familiar device for onlline graphic input is the light pen which consists of on-line photosensor which produces an electric output when it senses a spot displayed on a computer-controlled cathode-ray tube. However, material cannot be traced from hard copy and there is not hard copy input. A number of relatively simple devices employ a mechanical linkage between a stylus and an analog or digital encoding transducer or potentiometer. The disadvantages of the coupled devices are the restrictions of the mechanical linkage, its basic analog nature and the unnaturalness of the use of a linked pen.
The Rand tablet closer matches mans existing dexterity with a penlike instrument on a horizontal surface and does not require hand-directed creation of information on a surface coincidental with a display device, such as in the light pen. However, the Rand tablet requires capacitive coupling through the stylus, and the tablets are very expensive, even in small sizes, due to the intricate complexity of the stylus following electronics.
Pressure-Sensing analog and digital sheet encoder tablets have been suggested but have not been adopted since the accuracy and resolution have been low, and the mechanical properties poor and failure and cost of the tablets have been potentially high.
OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of theinvention to provide a pressure-sensing encoder tablet that is reliable, of relatively low cost and provides output signals indicative of the location of a free-pen, stylus or pencil.
A further object of the invention is the provision of a pressure-sensing encoder that is not sensitive to forces applied to the face of the tablet encoder from large objects but is sensitive to the forces applied to the tablet from the writing point of a pen, pencil or stylus.
Another object of the invention is the provision of a freepen writing tablet that directly converts movement of a pen, pencil or stylus over a platen or paper into electrical signals, the magnitude of which is proportional to the position of the writing instrument on the platen or paper.
These and other objects and many attendant advantages of the invention wiil become apparent as the description proceeds.
The pressure-sensing encoder tablet in accordance with the invention detects the movement of an electrically and mechanically uncoupled pointed writing instrument over the surface thereof. The tablet comprises a first deformable sheet having an electrically conductive surface, a second sheet having an electrically conductive surface and a resilient insulator sheet disposed between the conductive surfaces of said first and second sheets. The resilient sheet contains a uniform pattern of writing instrument point receiving perforations. The first and second sheets preferably comprise a thin sheet of deformable organic synthetic resin, such as Mylar (a polyester), having coated thereon a thin layer of metal, such as copper, silver, gold or aluminum, which may be in the form of a continuous film or in a grid of thin spaced parallel conductive lines. The assembly of deformable sheets is preferably supported on a rigid platen, such as a sheet of glass.
The resilient insulator sheet serves to electrically insulate the first and second conductive sheets during normal unstressed conditions. On the application of writing pressure, the perforations, which are from about 2 to 8 mils in diameter and are separated by about 1 to 3 mils, permit the point of the writing instrument to deform the top sheet into said perforation to a sufiicient depth to make contact between the conductive surfaces of said first and second sheets.
The resilient insulator sheet has sufficient compressibility to avoid contact between the sheets when the hand of the writer presses on the surface of the top sheet or when the pen or other light implement is laid on the surface of the tablet. The resilient insulator sheet is preferably a diene elastomer, such as natural rubber, or a synthetic butadiene copolymer, such as SBR having a thickness of l to 3 mils and a compressive strength about 5 pounds per square inch, preferably about 20 pounds per square inch, and a Shore Hardness of from 30 to 40 percent.
The tablet can further include means for impressing an electrical signal on said first sheet and means connected to said first and second sheets for detecting the value of said signal to provide a signal indicative of the location of the writing instrument point wherever it makes contact between said sheets.
The invention will now become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic illustration of a single-coordinate, free-pen, encoding tablet;
FIG. 2 is a cross-sectional view of the tablet of FIG. 1 shown with a ball-pen point applied to a sheet of paper;
FIG. 3 is a block and schematic diagram of a system for forming a resilient, perforated insulator sheet according to the invention;
FIG. 4 is a cross-sectional view of one form of tablet designed to detect by pressure the X and Y coordinates of the writing point;
FIG. 5 is a schematic view of a digital tablet;
FIG. 6 is a cross-sectional view of the tablet of FIG. 5:
FIG. 7 is an enlarged view of an intersection of the grid lines of the tablet of FIG. 5; and
FIG. 8 is a further view of the tablet of FIG. 5 showing a point contact of the grid lines induced by pressure of a ballpen point.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2, a single-coordinate encoding tablet 10 is illustrated. The tablet 10 includes a thin resistive top sheet 12 and a conductive bottom sheet 14 separated by a resiliently deformable perforated elastomer sheet 16. The perforations 17 are arranged in a repeating line pattern and are of a diameter sufficient to accept the deformation produced in the top sheet 12 by means of a writing instrument point 18 to a sufficient depth to make contact during deformation between the top and bottom sheets 12 and 14.
The top sheet 12 is formed of a thin conductive film, such as copper, and electrode busses 20 of a highly conductive metal, such as silver or gold, are provided along each edge of the sheet. A source of potential 19 is connected to the busses 20 and applied across the top sheet 12. Pressure from the writing point 18 of the writing instrument onto a sheet of paper 21, forces the paper sheet, and top sheet 12 into the perforation 17 and makes contact between sheets 12 and 14 at a given point 25 inducing an analog voltage signal detected at the edge 24 of sheet 14, the signal value being proportional to the X-coordinate of the point contact location.
The thin metallic films are preferably supported on thin deformable insulative organic resin plastic substrates such as polyethylene or a polyester, for example, Mylar. The substrate and films are of minimum thickness compatible with the desired mechanical properties of the final tablet, and suitably,
the substrate and metal film are each from below l to 3 mils in thickness. The top sheet may contain a continuous metallic film or may contain a series of parallel separated lines forming a grid. The spacing of the lines is selected to provide coordinate detection signals compatible with acceptable line resolution for-the desired application and is usually from 30 lines per inch to 200 lines per inch.
The size of the tablet is determined by the application. It can be typical letter size of 8% inches by l l inches or can be of smaller dimensions to accommodate business forms as in conventional telewriter instruments or of larger size for use in on-line date processing as a graphic input to a man-computer interface system.
The tablet of the invention is intended to permit completely natural manipulation of the penlike writing instrument. In the natural writing position, the edge of the palm rests on the tablet surface and distributes the weight of the arm to the surface. The fingers and wrist then apply sufficient pressure to the pen point to mark a sheet of paper and to simultaneously bring the conductive surfaces together at the contact point to develop a marking signal.
The resilient perforated elastomer sheet has a compressive strength sufficient to resist the pressure applied by the weight of the hand, suitably above p.s.i and preferably about p.s.i., but deforms to permit contact of the conductive sheets through the perforations when a pen point is applied. A ball pen point is typically about to 40 mils in diameter. Writing force sufficient to provide a permanent copy of paper and to deform the underlying tablet of about 0.5 to 3 pounds will distribute about at least 10' psi. to the tablet through the point.
The thickness of the resilient sheet is maintained as low as possible consistent with maintaining separation of the sheets under normal hand pressure and is preferably from 1 to 3 mils in thickness. An elastomer such as SBR rubber having a Shore Hardness of 30-40 will provide sufficient compressive resistance to normal hand forces and will deform under theforce of a writing point.
The perforations are of a diameter to accept under writing point pressure the deformed top conductive film and, its backing and paper, if present, to a sufficient depth to provide contact with the sheets. For a 27 mil writing point, the perforations are suitably about 4 to 6 mils and for a 40 mil point about 6 to 8 mils. The perforations are spaced to provide a resolution of 30 to 200 lines per inch.
When the conductive or resistive sheet is provided in the form of a grid, the perforations are spaced over the grid lines and the grid line thickness is selected to provide a wide base sized perforations could not be provided. However, in accordance with this invention, a rubber is conveniently and accurately perforated by applying a laser beam collimated to the desired diameter to the sheet and scanning the sheet with the laser and pulsing the laser at the center of each perforation location.
Referring now to FIG. 3, a laser 30 pulsed by power source 32 to form a beam collimated by lens 31 onto a sheet 36. The laser 30 is incrementally driven by scan drive 34 across a sheet 36 of elastomer. The power source 32 pulses the laser 30 at each perforation location corresponding to an increment of the scan drive movement. At the end of each line of movement, the scan drive returns to the opposite edge of the sheet and the drive rolls 38 advance the sheet one increment to the succeeding line.
The Y-coordinate of the writing point can be detected by providing a second assembly of resistive and conductive sheets in registration with those ofFlG. 1. Referring now to FIG. 4, one form of an analog tablet encoder includes a rigid glass platen 40 having a thin conductive film 42 applied to the surface thereof. The film 42 is separated from a thin resistive film 44 by a perforated, insulator elastomer sheet 46. The resistive film 44 is applied to a deformable Mylar sheet 48 which car' ries a second resistive film 50 on the top surface thereof. The second film 50 is covered with a second perforated elastomer sheet 52 which is turn is covered with a conductive film 54 supported on a Mylar sheet 56, the top surface 58 of which receives a writing point directly or indirectly through a sheet of paper 60 placed on the top surface thereof.
An X-axis voltage source 66 is applied to the top and bottom of second resistive film 50 and X-axis analog voltage is detected from the edge of conductive film 54. A second Y-axis voltage source 64 is applied across resistive film 44, and an X- axis analog voltage output is derived from the edge of conductive film 42.
Variations of the analog sheet encoder can readily be provided to follow the movement of the writing instrument. Phase detection or frequency difference techniques can be utilized to produce X and Y signals indicative of the location of the contact point. However, the analog systems have an inherently low accuracy due to electrical or mechanical interference and analog drift.
Referring now to FIGS. 5 and 6, a simplified digital system is illustrated comprising a rigid glass platen 70 on which is printed an X-line grid 72. For purposes of simplification, only 5 lines of the grid are illustrated. A perforated resilient elastomer sheet 74 is interposed between the grid 72 and an X-grid 76 supported on a top Mylar sheet 78 which forms the surface of the tablet.
Each one 80 of the X-grid 76 is connected to resistors 82 R,R which are of different incremental values such as l, 2, 4, 8 and 16 ohms. The resistors R,--R are imprinted onto the bottom surface of the Mylar sheet 78 and are connected to a thin film forming a bus 86 along one edge of the sheet. The X- grid lines 80 are connected to a second bus 90 along the second edge of the sheet. A voltage source 92 is connected to busses 86 and 90. Contact at any intersection 91 of the X- and Y- lines 80 and 81 will develop an output voltage in the Y-lines which is indicative both of the X- and y-locations by the fact that the selected Y-line is energized and by the fact that the X- voltage signal will be a digital value related to the resistor connected to that X-line. The combined X-Y signal is then sent to a decoding section for further processing and utilization.
Referring now to FIG. 7, an enlarged section of a l00-lpi tablet is disclosed. The X- and Y- lines 80 and 81 are each 2 mils in width and are separated by 8 mils. The perforation 96 through each sheet is 8 mils in diameter and the perforations disposed on 10 mil centers and, therefore, a 2 mil section of rubber remains between each perforation. A 40 mil pen point 98 when applied to the top surface of Mylar sheet 78 will make point contact between X and Y- lines 80 and 81 at the intersection 91 thereof.
The pressure-sensing encoder tablet of this invention can be utilized to sketch, edit, compose or trace straight or curvilinear data. lt can be utilized in telewriter transmitters or as a graphic input to a computer controlled cathode-ray tube display. The display control can multiplex the pen position information with computer-generated information so the the CRT displays a composite of the pen position and the computer. The horizontal surface and use of pen or pencil offers complete naturalness to the user.
lclaim:
l. A pressure-sensing encoder tablet for detecting the movement of a pointed writing instrument over the surface thereof comprising in combination:
a first sheet comprising a deformable of synthetic organic resin having a thin electrically conductive layer of metal coated on one surface thereof;
a second sheet having an electrically conductive surface facing the electrically conductive layer of the first sheet;
a resilient, deformable insulating sheet consisting essentially of a diene elastomer having a thickness of from i to 3 mils and a compression strength sufficient to withstand at least psi. without permitting contact of the conductive surfaces of said first and second sheets disposed between the conductive surfaces of said first and second sheets; said insulating sheet containing a uniform pattern of writing point receiving perforations having substantially the same diameter of between 2 to 8 mils and substantially the same separation between perforations of from 1 to 3 mils; and
a rigid platen for supporting said sheets.
2. A tablet according to claim 1 further including means for impressing an electrical signal on said first sheet and means connected to said first and second sheet for detecting the value of said signal.
3. A tablet according to claim 1 in which said second sheet comprises a sheet of conductive metal.
4. A tablet according to claim 1 in which said first and second sheets comprise a film of conductive metal adherent to a sheet of deformable synthetic organic plastic.
5. A tablet according to claim 1 in which said platen is formed of glass.
6. A tablet according to claim 1 in which said tablet further includes a third conductive sheet and a second perforated resilient insulator sheet; said tablet being assembled with said third conductive sheet disposed between said insulator sheets with the outer surface of said insulator sheets in contact with the conductive surfaces of said first and second sheets.
7. A tablet according to claim 1 in which said writing point has a diameter from about 30 to 40 mils.
8. A tablet according to claim I in which said conductive layer is in the form of a grid comprising a series of spaced, parallel conductive lines of metal.
9. A tablet according to claim 8 further including a differently valued resistor connected to each of said lines.
10. A tablet according to claim 9 further including means for impressing a voltage on said lines and means connected to said first and second sheets for detecting the voltage drop through each of said lines.
11. A tablet according to claim 1 in which the Shore hardness of said elastomer is about 30 to 40.
12. A tablet according to claim 11 in which said sheet is perforated by vaporization of sheet material by a laser beam collimated to the diameter of the perforation.
10! i I! It III

Claims (12)

1. A pressure-sensing encoder tablet for detecting the movement of a pointed writing instrument over the surface thereof comprising in combination: a first sheet comprising a deformable film of synthetic organic resin having a thin electrically conductive layer of metal coated on one surface thereof; a second sheet having an electrically conductive surface facing the electrically conductive layer of the first sheet; a resilient, deformable insulating sheet consisting essentially of a diene elastomer having a thickness of from 1 to 3 mils and a compression strength sufficient to withstand at least 20 p.s.i. without permitting contact of the conductive surfaces of said first and second sheets disposed between the conductive surfaces of said first and second sheets; said insulating sheet containing a uniform pattern of writing point receiving perforations having substantially the same diameter of between 2 to 8 mils and substantially the same separation between perforations of from 1 to 3 mils; and a rigid platen for supporting said sheets.
2. A tablet according to claim 1 further including means for impressing an electrical signal on said first sheet and means connected to said first and second sheet for detecting the value of said signal.
3. A tablet according to claim 1 in which said second sheet comprises a sheet of conductive metal.
4. A tablet according to claim 1 in which said first and second sheets comprise a film of conductive metal adherent to a sheet of deformable synthetic organic plastic.
5. A tablet according to claim 1 in which said platen is formed of glass.
6. A tablet according to claim 1 in which said tablet further includes a third conductive sheet and a second perforated resilient insulator sheet; said tablet being assembled with said third conductive sheet disposed between said insulator sheets with the outer surface of said insulator sheets in contact with the conductive surfaces of said first and second sheets.
7. A tablet according to claim 1 in which said writing point has a diameter from about 30 to 40 mils.
8. A tablet according to claim 1 in which said conductive layer is in the form of a grid comprising a series of spaced, parallel conductive lines of metal.
9. A tablet according to claim 8 further including a differently valued resistor connected to each of said lines.
10. A tablet according to claim 9 further including means for impressing a voltage on said lines and means connected to said first and second sheets for detecting the voltage drop through each of said lines.
11. A tablet According to claim 1 in which the Shore hardness of said elastomer is about 30 to 40.
12. A tablet according to claim 11 in which said sheet is perforated by vaporization of sheet material by a laser beam collimated to the diameter of the perforation.
US792118*A 1969-01-17 1969-01-17 Pressure-sensing tablet Expired - Lifetime US3624619A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US79211869A 1969-01-17 1969-01-17

Publications (1)

Publication Number Publication Date
US3624619A true US3624619A (en) 1971-11-30

Family

ID=25155855

Family Applications (1)

Application Number Title Priority Date Filing Date
US792118*A Expired - Lifetime US3624619A (en) 1969-01-17 1969-01-17 Pressure-sensing tablet

Country Status (1)

Country Link
US (1) US3624619A (en)

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3727002A (en) * 1971-03-29 1973-04-10 Potter Instrument Co Inc Magnetic method for digitally identifying the location of an applied force
US3806704A (en) * 1971-08-02 1974-04-23 T Shinal Identification system
US3806912A (en) * 1972-06-13 1974-04-23 Burroughs Corp Graphical input board
US3894183A (en) * 1971-06-30 1975-07-08 Benjamin J Barish Stylus actuated electrical devices
US3906190A (en) * 1972-06-30 1975-09-16 Nat Res Dev Apparatus for integration and averaging
US3914548A (en) * 1971-06-30 1975-10-21 Benjamin J Barish Stylus actuated electrical device and electrical kit including same
US4035768A (en) * 1976-05-03 1977-07-12 Veripen, Inc. Personal identification apparatus
US4304991A (en) * 1979-09-26 1981-12-08 Weber Harold J Indicia sensor apparatus
EP0073373A1 (en) * 1981-08-28 1983-03-09 Kabushiki Kaisha Toshiba Coordinate input device with pressure-sensitive rubber sheet
EP0099430A1 (en) * 1982-07-19 1984-02-01 Oki Densen Kabushiki Kaisha Pressure-sensitive conductive elastic sheet and method of forming same
EP0107898A2 (en) * 1982-09-29 1984-05-09 EMI Limited A tactile array sensor
US4448837A (en) * 1982-07-19 1984-05-15 Oki Densen Kabushiki Kaisha Pressure-sensitive conductive elastic sheet
US4493104A (en) * 1981-12-11 1985-01-08 Moore Business Forms, Inc. Character recognition device
US4503286A (en) * 1982-07-03 1985-03-05 Alps Electric Co., Ltd. Input device
US4504700A (en) * 1982-07-03 1985-03-12 Alps Electric Co., Ltd. Input device
FR2556113A1 (en) * 1983-12-06 1985-06-07 Pellizzari Paolo Transmission panel for a visual display device and method of manufacture
WO1986003618A1 (en) * 1984-12-12 1986-06-19 The Regents Of The University Of California Tactile sensor devices
US5627349A (en) * 1993-07-01 1997-05-06 Integral Information Systems Interactive data entry apparatus
US20130145856A1 (en) * 2011-12-09 2013-06-13 Canon Kabushiki Kaisha Pressure-sensitive sensor, and grip apparatus and robot manipulator equipped with the same
US20140043289A1 (en) * 2012-08-07 2014-02-13 N-Trig Ltd. Capacitive sensor for a digitizer system
US20150370373A1 (en) * 2014-06-23 2015-12-24 Microsoft Technology Licensing, Llc Capacitive based digitizer sensor
US10380175B2 (en) 2017-06-06 2019-08-13 International Business Machines Corporation Sketch-based image retrieval using feedback and hierarchies

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3005050A (en) * 1956-12-28 1961-10-17 Bell Telephone Labor Inc Telautograph system
US3308253A (en) * 1965-03-25 1967-03-07 Ibm Diaphragm switch having a diaphragm supported on an incompressible layer and an elastomer overlaying the diaphragm

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3005050A (en) * 1956-12-28 1961-10-17 Bell Telephone Labor Inc Telautograph system
US3308253A (en) * 1965-03-25 1967-03-07 Ibm Diaphragm switch having a diaphragm supported on an incompressible layer and an elastomer overlaying the diaphragm

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3727002A (en) * 1971-03-29 1973-04-10 Potter Instrument Co Inc Magnetic method for digitally identifying the location of an applied force
US3894183A (en) * 1971-06-30 1975-07-08 Benjamin J Barish Stylus actuated electrical devices
US3914548A (en) * 1971-06-30 1975-10-21 Benjamin J Barish Stylus actuated electrical device and electrical kit including same
US3806704A (en) * 1971-08-02 1974-04-23 T Shinal Identification system
US3806912A (en) * 1972-06-13 1974-04-23 Burroughs Corp Graphical input board
US3906190A (en) * 1972-06-30 1975-09-16 Nat Res Dev Apparatus for integration and averaging
US4035768A (en) * 1976-05-03 1977-07-12 Veripen, Inc. Personal identification apparatus
US4304991A (en) * 1979-09-26 1981-12-08 Weber Harold J Indicia sensor apparatus
EP0073373A1 (en) * 1981-08-28 1983-03-09 Kabushiki Kaisha Toshiba Coordinate input device with pressure-sensitive rubber sheet
US4475008A (en) * 1981-08-28 1984-10-02 Tokyo Shibaura Denki Kabushiki Kaisha Coordinate input device with pressure-sensitive rubber sheet
US4493104A (en) * 1981-12-11 1985-01-08 Moore Business Forms, Inc. Character recognition device
US4504700A (en) * 1982-07-03 1985-03-12 Alps Electric Co., Ltd. Input device
US4503286A (en) * 1982-07-03 1985-03-05 Alps Electric Co., Ltd. Input device
EP0099430A1 (en) * 1982-07-19 1984-02-01 Oki Densen Kabushiki Kaisha Pressure-sensitive conductive elastic sheet and method of forming same
US4448837A (en) * 1982-07-19 1984-05-15 Oki Densen Kabushiki Kaisha Pressure-sensitive conductive elastic sheet
EP0107898A3 (en) * 1982-09-29 1984-08-15 Emi Limited A tactile array sensor
EP0107898A2 (en) * 1982-09-29 1984-05-09 EMI Limited A tactile array sensor
FR2556113A1 (en) * 1983-12-06 1985-06-07 Pellizzari Paolo Transmission panel for a visual display device and method of manufacture
WO1986003618A1 (en) * 1984-12-12 1986-06-19 The Regents Of The University Of California Tactile sensor devices
US4668861A (en) * 1984-12-12 1987-05-26 The Regents Of The University Of California Tactile sensor employing a light conducting element and a resiliently deformable sheet
US5627349A (en) * 1993-07-01 1997-05-06 Integral Information Systems Interactive data entry apparatus
US20130145856A1 (en) * 2011-12-09 2013-06-13 Canon Kabushiki Kaisha Pressure-sensitive sensor, and grip apparatus and robot manipulator equipped with the same
US8875584B2 (en) * 2011-12-09 2014-11-04 Canon Kabushiki Kaisha Pressure-sensitive sensor, and grip apparatus and robot manipulator equipped with the same
US20140043289A1 (en) * 2012-08-07 2014-02-13 N-Trig Ltd. Capacitive sensor for a digitizer system
US20150370373A1 (en) * 2014-06-23 2015-12-24 Microsoft Technology Licensing, Llc Capacitive based digitizer sensor
US10234996B2 (en) * 2014-06-23 2019-03-19 Microsoft Technology Licensing, Llc Capacitive based digitizer sensor
US10380175B2 (en) 2017-06-06 2019-08-13 International Business Machines Corporation Sketch-based image retrieval using feedback and hierarchies

Similar Documents

Publication Publication Date Title
US3624619A (en) Pressure-sensing tablet
EP0288692B1 (en) Graphics input tablet
US5113041A (en) Information processing
US5072076A (en) Tablet digitizer with untethered stylus
US4899137A (en) Arrangement for the input and processing of characters and/or graphic patterns
US5942733A (en) Stylus input capacitive touchpad sensor
EP0073373B1 (en) Coordinate input device with pressure-sensitive rubber sheet
US4636582A (en) Signal input sheet having a conductive shield layer
JP2001243010A (en) Inputting device
EP0610262A4 (en) See-through digitizer with clear conductive grid.
WO1992010823A1 (en) Touch sensor and controller
US5010213A (en) Signal input sheet
JPH0944289A (en) Input pad system
JPS6222135A (en) Transparent graphic input tablet
JPH06149463A (en) Coordinate input device
JP2666929B2 (en) Information input sheet
US5411790A (en) Signal input sheet
US6151013A (en) Electrical probe-position sensor
JPS6130289B2 (en)
JPS58200384A (en) Coordinate reader
JP6707910B2 (en) Writing board and display system
JP2001084087A (en) Handwritten input device
JP6707911B2 (en) Writing board system
KR0162314B1 (en) Computer input device
JPS6129931A (en) Position detector