Methods and apparatus for data input

• US 5,305,017 A
• Filed: 07/13/1992
• Issued: 04/19/1994
• Est. Priority Date: 08/16/1989
• Status: Expired due to Term

• Current Assignee: Cirque Corporation
• Original Assignee: George E. Gerpheide
• Inventors: Gerpheide, George E.
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): FATAHI YAR, MAHMOUD
• Application Number:
  US07/914,043
• Time in Patent Office: 645 Days
• Field of Search: 340/706, 340/709, 340/710, 340/712, 341/20, 341/23, 178/18, 178/19, 345/173, 345/174, 345/168
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0213 Arrangements providing an integrated pointing device in a keyboard, e.g. trackball, mini-joystick for pointing devices integrated in a laptop computer G06F1/169; joysticks G05G9/047; constructional details of pointing devices G06F3/033
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

Methods and apparatus for data input. Devices are provided in accordance with this invention which utilize capacitive coupling of an object to the device to sense the object'"'"'s position. The devices are comprised of a plurality of electrode strips which form virtual electrodes. The virtual electrodes are selectively connected to form virtual dipole electrodes which are responsive to the object'"'"'s position.

Claims

1. Apparatus for data input through sensing the position of a passive object relative to the apparatus comprising:

pad means for sensing the object'"'"'s position, the pad means having

a plurality of first electrode strips spaced apart in a first array,

one or more second electrode strips disposed in proximity to the first electrode strips to cross thereover for establishing electric fields, including fringe electric fields, between the second electrode strip and selected first electrode strips, to thereby develop capacitive balances in the pad means,

wherein the object perturbs a fringe electric field when the object comes in proximity to the pad means, thereby changing the capacitive balances; and

measurement means operatively coupled to the pad means for measuring the capacitive balances in the pad means to thereby determine the position of the object relative to the pad means, said measurement means including

synthesis means responsive to control signals for selecting first electrode strips which, along with the second electrode strip, will develop electric fields,

control means for supplying control signals to the synthesis means to designate the selected first electrode strips,

means for causing development of electric fields between the selected first electrode strips and the second electrode strip, and

means for detecting the changes in capacitive balances in the pad means and the locations of such changes.

2. The apparatus recited in claim 1 wherein the pad means further comprises:

insulator means having first and second sides electrically interfaced with the plurality of first electrode strips on the first side for providing an insulating substrate for the pad means; and

said second electrode strip being interfaced with the insulator means on the second side.

3. The apparatus recited in claim 2 wherein said pad means further comprises a plurality of second electrode strips spaced apart in a second array to extend at an angle to the direction in which the first electrode strips extend so that each electrode strip in the first array intersects each electrode strip in the second array at an intersecting location, and wherein the causing means includes means for supplying signals to selected electrode strips in the first array and second array to thereby establish electric fields between the selected electrode strips of the first array and the selected strips of the second array at intersecting locations.

4. The apparatus recited in claim 3 wherein said causing means further includes means for supplying signals to selected pairs of electrode strips in the first array to thereby form selected virtual dipole electrodes in the first array, and to selected pairs of electrode strips in the second array to thereby form selected virtual dipole electrodes in the second array, each virtual dipole electrode having a positive half electrode strip and a negative half electrode strip such that electric fields are established between selected halves of one polarity in the first array, and selected halves of the opposite polarity in the second array.

5. The apparatus recited in claim 4 wherein said detecting means comprises

means for successively calculating capacitive balances between selected halves of virtual dipole electrodes in the first array and halves of virtual dipole electrodes in the second array,

means for calculating capacitive balance ratios for selected pairs of calculated capacitive balances, and

means for calculating the position of the object relative to the pad means from the calculated capacitive balance ratios and the locations of the virtual dipole electrodes producing the calculated capacitive balances.

6. The apparatus recited in claim 1 wherein the apparatus is mounted to a keyboard input device of a computer.

7. The apparatus recited in claim 6 wherein the object is electrically passive.

8. Apparatus for sensing an object'"'"'s position, the apparatus adapted to respond to the object'"'"'s distortion of an electric field comprising:

insulator means having first and second sides for providing an insulating substrate to the apparatus;

a plurality of first electrode means disposed on the first side of the insulator means;

a plurality of second electrode means disposed on the second side of the insulator means for establishing electric fields in cooperation with the first electrode means;

balance measurement means for measuring capacitive balances among selected ones of the first electrode means and second electrode means;

synthesis means operatively coupled to the first electrode means and the second electrode means and responsive to control signals for selecting certain ones of the first electrode means and second electrode means to repeatedly synthesize virtual dipole electrodes, among which capacitive balances are to be measured by the balance measuring means;

control means operatively coupled to the synthesis means for supplying control signals to the synthesis means to thereby specify which of the first electrode means and second electrode means are selected by the synthesis means; and

balance ratio determination means operatively coupled to the balance measuring means for determining electrical balance ratios among the virtual dipoled electrodes.

9. The apparatus recited in claim 8 further comprising dielectric insulating means overlaying the first electrode means for preventing the object from making contact with the first electrode means.

10. The apparatus recited in claim 8 wherein the apparatus is mounted to a keyboard data input device of a computer.

11. A method of measuring an object'"'"'s position comprising the steps of:

providing an electrically sensitive pad comprising;

insulator means having first and second sides for providing an insulating substrate to the apparatus;

first electrode means electrically coupled to the first side of the insulator means for establishing an electric field;

second electrode means electrically coupled to the second side of the insulator means for further establishing the electric field in cooperation with the first electrode means;

synthesis means operatively coupled to the first electrode means and the second electrode means for selecting first electrode means and second electrode means to repeatedly synthesize virtual dipole electrodes, the virtual dipole electrodes being adapted to develop an electrical balance responsive to the object'"'"'s distortion of

the electric field;

measuring electrical balances between the first electrode means and the second electrode means;

calculating the object'"'"'s coarse position based on at least one target index;

calculating the object'"'"'s fine position based on the measured balances between the first electrode means and the second electrode means; and

calculating the object'"'"'s net position based on the object'"'"'s calculated coarse and fine positions.

12. The method recited in claim 11 wherein the object'"'"'s net position is the sum of the object'"'"'s coarse position and the object'"'"'s fine position.

13. The method recited in claim 12 further comprising the step of updating the target index.

14. The method recited in claim 13 wherein the step of calculating the object'"'"'s fine position further comprises:

calculating a first electrical balance between a first upper virtual dipole electrode defined by the first electrode means and a lower virtual dipole electrode defined by the second electrode means, the first upper and lower virtual dipole electrodes being determined by the target index;

calculating a second electrical balance between a second upper virtual dipole electrode defined by the first electrode means and a lower virtual dipole electrode defined by the second electrode means, the second upper virtual dipole electrode being determined by a target index offset;

calculating an electrical balance ratio between the first and second electrical balances; and

calculating the object'"'"'s fine position based on the electrical balance ratio and the position of the virtual dipole electrodes.

15. The method recited in claim 14 wherein the steps of calculating the first and second electrical balances further comprises measuring capacitances between the first electrode means and the second electrode means and algebraically summing the capacitance values between the electrode means.

16. The method recited in claim 15 wherein the electrical balance ratio follows the relationship:

##EQU1## where Q=electrical balance ratio,

L1=the first electrical balance, and

LN=the second electrical balance.

17. The method recited in claim 16 wherein the object'"'"'s fine position is calculated according to the following relationship:

space="preserve" listing-type="equation">Fine position=(XN-X)*Q,

where

X=a location of the first upper virtual dipole electrode, and

XN=a location of the second upper virtual dipole electrode.