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EP0815550A1 - Systeme d'etalonnage pour ecrans tactiles - Google Patents

Systeme d'etalonnage pour ecrans tactiles

Info

Publication number
EP0815550A1
EP0815550A1 EP96907868A EP96907868A EP0815550A1 EP 0815550 A1 EP0815550 A1 EP 0815550A1 EP 96907868 A EP96907868 A EP 96907868A EP 96907868 A EP96907868 A EP 96907868A EP 0815550 A1 EP0815550 A1 EP 0815550A1
Authority
EP
European Patent Office
Prior art keywords
controller
coordinates
touch screen
calibration
crt
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.)
Withdrawn
Application number
EP96907868A
Other languages
German (de)
English (en)
Inventor
Keith Lia
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.)
Elo TouchSystems Inc
Original Assignee
Elo TouchSystems Inc
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 Elo TouchSystems Inc filed Critical Elo TouchSystems Inc
Publication of EP0815550A1 publication Critical patent/EP0815550A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; 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
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment
    • G06F3/04186—Touch location disambiguation
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/22—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing
    • G06F11/2205—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing using arrangements specific to the hardware being tested
    • G06F11/2221—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing using arrangements specific to the hardware being tested to test input/output devices or peripheral units

Definitions

  • the present invention relates to a method and apparatus for the calibration of a touch screen for a cathode ray tube (CRT) and relates particularly, although not exclusively, to a method and apparatus for the calibration of a touch screen for a TV receiver or computer display unit.
  • CTR cathode ray tube
  • the invention has particular application to an interactive
  • CD player Such devices are sold by Philips Consumer Electronics
  • the CD-i player can play CD disks in the 3 inch or 5 inch format.
  • the disks may include sound and visuals and provide a menu based interactive information system.
  • pointing devices may be coupled to the CD-i player e.g. mouse, trackball, joystick, light pen, etc.
  • the pointing devices are coupled to the CD-i player through a serial port based on the
  • a special data format is sent to the serial port which the CD-i player decodes to position a cursor on the screen with movement of the pointing device.
  • a touch screen can also be used where a finger or pen is pushed onto the desired menu option on the CRT for the interaction between the CD-i player and user.
  • Touch screens are readily available items which are affixed to the front of the CRT.
  • a typical touch screen may be found in U.S. Patent No. 3,911,215, the contents of which are incorporated into this specification.
  • the touch screen has a thin, rigid glass panel that is mounted to the CRT.
  • the glass panel has a transparent electrically resistive coating on the inside. Gas- tight electrical contacts are then made to this coating in such a manner as to permit it to be used as a highly stable linear voltage divider for both the X and Y axes.
  • a plastic contact sheet with a transparent conductive coating is stretched tightly over the glass substrate. The contact sheet is held above the glass by small, clear separator points, which are evenly distributed on the inside contact sheet surface.
  • Finger pressure causes the contact sheet to deform imperceptibly and make electrical contact with the resistive coating at the position of touch.
  • the voltages picked off by the contact sheet at the point of contact are the analog representation of the position touched.
  • a controller circuit separate from the touch screen impresses the voltage gradient across the resistive coating on the glass, alternating between the X and Y directions.
  • the analog signals picked off by the contact sheet are digitised by an analog-to- digital converter in the controller, and the digitised coordinate pair is then transmitted to the computer or CD-i player for processing.
  • a touch screen is an absolute positional device and the coordinate system of the touch screen must be aligned with that of the raster.
  • the touch screen typically has a range of from 0 to 1024 points across the screen and the same up the screen.
  • the coordinates are sent to the controller. These coordinates should reflect the area of the video image the user wishes to select. If the video image does not line up with the expected touch screen coordinates, then calibration is required. This can be achieved by the following methods: 1. Adjust the video image to suit the touch screen. This is done by adjusting the height and width controls associated with the CRT. This method has the disadvantage of limited accuracy and is labour intensive. 2. On normal computer systems a special calibration program is run which places a bit map video image with touch targets on the screen.
  • a further object of the invention is to provide a calibration system which is simple and fast to operate.
  • a still further object is to provide a calibration system which can easily interface to existing computer or interactive video systems which does not require additional software.
  • the present invention in a first aspect provides a method of calibration of a touch screen for a cathode ray tube (CRT) to allow coordinates provided by said touch screen to correspond with desired coordinates of a video image supplied by a host system, said method including the steps of providing a calibration signal, moving a cursor to a first predetermined location on said CRT on receipt of said calibration signal, storing data representing the actual and sampled coordinates of said first predetermined location from a first touch on said touch screen, moving said cursor to a second predetermined location on said CRT, storing data representing the actual and sampled coordinates of said second predetermined location from a second touch on said touch screen and using stored data for a calibration correction based on said first and second samplings for, in use, allowing coordinates provided by said touch screen to correspond with the desired coordinates of the video image supplied by said host system.
  • CTR cathode ray tube
  • said sampling of said first and second coordinates occurs multiple times to filter said sampling.
  • said calibration signal must be held for a predetermined time before said cursor is moved to said first predetermined position.
  • the invention may also provide a method of correcting sampled coordinates from a touch screen for a cathode ray tube (CRT) supplied with a video image from a host system, said method including the steps of sampling the coordinates of a touched location on said touch screen and correcting the sampled coordinates using a calibration correction from said above method of calibration.
  • CTR cathode ray tube
  • a controller for a touch screen used on a cathode ray tube (CRT) said controller including an interface for coupling to a host system which provides video images to said CRT, a detector monitored by said controller to indicate a user's desire to calibrate said controller, said controller being responsive to said detector to cause a calibration sequence to be performed by said controller, a non-volatile memory for storage of the results of the calibration sequence, said controller adapted to monitor coordinates from said touch screen, and to apply a correction to the said coordinates to provide said host system with corrected coordinates using said calibration results stored in said non ⁇ volatile memory.
  • CTR cathode ray tube
  • Fig. 1 is a block circuit diagram of a controller incorporating the invention for a touch screen
  • Fig. 2 is a schematic of the touch screen with its connections
  • Figs. 3a, 3b and 3c together form a circuit schematic diagram of the controller shown in Fig. 1;
  • Fig. 4 is a circuit schematic diagram showing the coupling of the controller to a CD-i player.
  • FIGs. 5a, 5b, 6a, 6b, 6c, 7a, 7b, 8a and 8b are flow charts showing the operation of the controller and its routines.
  • FIGs. 1 to 4 illustrate the hardware for realising the invention.
  • a touch screen 10 is fitted to a conventional television screen 11 (not shown) and is typically an E274 AccuTouchTM touch screen sold by Elographics, Inc. The construction of this touch screen is described in U.S. Patent No. 3,911, 215.
  • Touch screen 10 is coupled via connector J4 to a serial controller 12 which incorporates the calibration system of the invention.
  • Connector J5 may be used for the Duratouch TM touch screens.
  • Touch screen 10 has screen lines (H,X,Y,L) and a sense line S.
  • Each of lines H, X, Y, L and S are protected by diodes Zl-Z 5 for the safe drain of any static buildup induced from the CRT 11.
  • the screen lines are driven by two octal 3-state noninverting buffer/line driver/line receiver integrated circuit chips U3, U4 (typically 74HC244 by Motorola).
  • Sense line S is coupled to an analog to digital converter U2 (typically a 10-bit A/D converter with serial interface designated MC145053 by Motorola) .
  • serial controller 12 is coupled to an interactive CD player 14 sold by Philips Consumer Electronics BV under the name Philips CD-i player.
  • Player 14 has a serial port connector 16 which is coupled to a corresponding connector Jl of serial controller 12 by a cable 18.
  • Cable 18 also incorporates a switch SI which indicates that calibration is required.
  • Switch SI can be a momentary closure switch which interfaces with a microcontroller or microprocessor Ul.
  • Ul is an 8-bit microcontroller unit designated MC68HC705C8 by Motorola.
  • Such a microcontroller has ROM, PROM, RAM, serial communication, interface 24 bidirectional I/O lines and 7 input-only lines integrated into the one chip.
  • Microcontroller Ul interfaces with analog to digital converter U2 and line drivers U3, U4.
  • Serial data communication with player 14 is by an RS-232 interface through an RS-232 driver/receiver chip U8.
  • U8 is typically a MAX232 by Maxim Integrated Products.
  • an electrically erasable programmable memory U6 is interfaced to microcontroller Ul.
  • Memory U6 is typically an NMC9306 chip by National Semiconductor.
  • Serial controller 12 interfaces to player 14 to transmit positional coordinates on detection of a screen touch, and to provide a calibration, if required, of touch screen 10 to ensure that the video image lines up with the expected touch screen coordinates. Calibration is obtained by driving the cursor to selected positions on screen 11 and saving those points in memory U6. These saved points can be used as correction factors for the raw coordinates received from touch screen 10.
  • Normally serial controller 12 will monitor touch screen 10 and pass "touch detection" and coordinates for processing by microcontroller Ul. Microcontroller Ul will translate the coordinates into the data format required by player 14 and transmit the data through serial interface U8.
  • the coordinate information is filtered in both hardware and software to prevent generation of incorrect coordinates. This filtering minimises the effect of electrical noise picked up from the face of screen 11.
  • Analog to digital converter U2 in this case is a successive approximation analog to digital converter having 10 bit resolution which operates ratiometrically to minimise effects of variations in drive voltages and drift with changing temperature.
  • the drive voltages for the Y coordinate are applied to the screen - H and Y high, and L and X low.
  • the analog signal for the Y position is provided from the touch screen contact sheet on the S line.
  • An A/D conversion is carried out and the result stored in memory.
  • This procedure of X and Y coordinate conversation is carried out four times in succession.
  • the four coordinates are then digitally filtered by the control software. If the spread of coordinates is too large, the sample is rejected as invalid.
  • a further touch detection step is performed to ensure that touch screen 10 remained pressed for the whole of the coordinate conversion time. If the touch screen 10 is released during conversion, the coordinates are rejected as invalid. Once an acceptable coordinate pair has been determined, the coordinate is sent via the serial port U8 to player 14.
  • the calibration results will be applied to the raw coordinate results to ensure that the correct coordinates are passed to player 14.
  • the corrected coordinates will be based on the following formulae.
  • X NORM & Y NORM are the normalised values after the calibration correction.
  • RAWX & RAWY are the raw unconverted coordinates.
  • CALXHI & CALYHI are the calibration points sent to the screen on the top RH quadrant.
  • CALXLO & CALYLO are the calibration points sent to the screen on the bottom LH quadrant.
  • CONVXHI & CONVYHI are the return values collected from the top RH quadrant.
  • CONVXHI & CONVYHI are the return values collected from the bottom LH quadrant.
  • the cursor in this mode can be controlled and put to any valid position within the above range of the video image. This is the method we use to obtain calibration points. In this case we use calibration coordinates at lOOh . lOOh & 300h,300h which simplifies the formula to:
  • the CDi output data format is an async 7 bit data with 2 stop bits. It transmits a binary format with 000 - 3FF hexadecimal absolute x and y coo-ordinates.
  • Serial controller 12 is an 8 bit character transmitter so bit 7 is padded to all ones. Pen down and button 2 are not used and are padded with zeros.
  • the invention provides a very effective touch screen controller which interfaces to player 14 without requiring touch screen drivers on the CD disk or requiring manipulation of the screen height and width controls. Once calibration has been set no further adjustment is necessary. The calibration is very simple and requires no special skills from the user.
  • Touch screen 10 can be substituted by another sourced device as can the integrated circuits.
  • a custom chip could be used to provide the required lines to touch screen 10 and serial port 16.
  • the preferred embodiment has disclosed operation with a Philips player 14. The invention is not limited to such players as it can be readily adapted for interfacing with a computer having a touch screen fitted.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Input By Displaying (AREA)

Abstract

Cette invention se rapporte à un contrôleur (12) pour un écran tactile (10) utilisé sur un tube cathodique (CRT). Ledit contrôleur comprend une interface (U8) pour le couplage à un système hôte (14) qui fournit des images vidéo audit tube cathodique. Un détecteur (S1) surveillé par le contrôleur (12) indique les instructions de l'utilisateur pour l'étalonnage du contrôleur (12). Ledit contrôleur réagit au détecteur (S1) pour qu'une séquence d'étalonnage soit exécutée par le contrôleur (12). Une mémoire rémanente (U6) stocke les résultats de la séquence d'étalonnage. Le contrôleur (12) est conçu pour surveiller les coordonnées provenant de l'écran tactile (10) et pour appliquer une correction auxdites coordonnées, afin de fournir au système hôte (14) les coordonnées corrigées en utilisant les résultats d'étalonnage stockés dans la mémoire rémanente (U6). Un procédé d'étalonnage est également décrit.
EP96907868A 1995-02-07 1996-02-05 Systeme d'etalonnage pour ecrans tactiles Withdrawn EP0815550A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPN0927A AUPN092795A0 (en) 1995-02-07 1995-02-07 Calibration system for touch screens
AUPN0927/95 1995-02-07
PCT/US1996/001597 WO1996024923A1 (fr) 1995-02-07 1996-02-05 Systeme d'etalonnage pour ecrans tactiles

Publications (1)

Publication Number Publication Date
EP0815550A1 true EP0815550A1 (fr) 1998-01-07

Family

ID=3785287

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96907868A Withdrawn EP0815550A1 (fr) 1995-02-07 1996-02-05 Systeme d'etalonnage pour ecrans tactiles

Country Status (3)

Country Link
EP (1) EP0815550A1 (fr)
AU (1) AUPN092795A0 (fr)
WO (1) WO1996024923A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1179768B1 (fr) * 2000-08-09 2010-09-01 Siemens Aktiengesellschaft Système informatique avec un ordinateur central et une pluralité de terminaux de commande
JP4096164B2 (ja) * 2002-06-10 2008-06-04 日本電気株式会社 ポインティングデバイスのセットアップ方法と該方法を記録した記録媒体および携帯端末
US7372456B2 (en) * 2004-07-07 2008-05-13 Smart Technologies Inc. Method and apparatus for calibrating an interactive touch system
CN111596802B (zh) * 2020-05-26 2022-12-02 Oppo（重庆）智能科技有限公司 一种触摸屏校准方法、装置及计算机可读存储介质
CA3147560A1 (fr) 2021-02-04 2022-08-04 1004335 Ontario Inc. carrying on business as A D Metro Configuration de systeme de capteur tactile
GB2608217B (en) 2021-03-12 2023-06-28 1004335 Ontario Inc Carrying On Business As A D Metro Methods for configuring touch sensor system

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4737773A (en) * 1984-09-04 1988-04-12 Nec Corporation Graphical display apparatus having a coordinate correction circuit
US4710758A (en) * 1985-04-26 1987-12-01 Westinghouse Electric Corp. Automatic touch screen calibration method
US4903012A (en) * 1987-01-20 1990-02-20 Alps Electric Co., Ltd. Coordinate system input device providing registration calibration and a mouse function

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9624923A1 *

Also Published As

Publication number Publication date
AUPN092795A0 (en) 1995-03-02
WO1996024923A1 (fr) 1996-08-15

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