US 4,736,191 A · Touch activated control method and apparatus

Abstract

A cursor control device (10) is provided which has a touch pad (14) formed of individual conductive plates (16) forming sectors of a circle. A user's touch on a dielectric layer (18) overlying the plates (16) is detected by individually charging and discharging each of the sector plates in a sequential manner to determine the increased capacitance, if any, of each sector plate. A microprocessor assigns each of the sector plates a relative X and Y weighting as a function of its angular position in the touch pad which are combined with the individual plate capacitance readings to calculate the relative X and Y position of the touch with respect to the origin (28) of the touch pad. Cursor control signals proportional to the relative X and Y values, plus a Z value proportional to the area of touch, if desired, are provided to the keyboard (12) of a displaying computer. The touch pad (14) can be effectively integrated into a computer keyboard by positioning it immediately beneath the space bar (25) of the keyboard so that it can be accessed by the thumb of the user without requiring the user to move his or her hand from the keyboard.

Claims31

Dependent claims

Apparatus for use in providing touch commands from a user, comprising:

(a) a touch pad having a plurality of plates defining sectors arrayed about a central origin, each sector plate formed of an electrically conductive material and electrically isolated from the other sector plates, the plates being covered by a dielectric layer which is exposed to the touch of a user;
(b) means electrically connected to each of the sector plates for detecting the relative area of each plate covered by an object which can capacitively couple thereto such as a user's finger based on a change in capacitance of each sector plate which will be in proportion to the area of the sector plate that is covered by the object, for calculating the relative X and Y positions of the object with respect to the rigin of the touch pad based on the relative areas of each late covered by the object, and for providing an output signal indicative thereof.

In a computer terminal having a keyboard with a standard set of alphanumeric keys and a spacer bar extending under the keys, the improvement comprising:

(a) a touch pad mounted in the keyboard immediately adjacent to and on the opposite side of the spacer bar from the keys such that the touch pad can be reached by the thumb of an operator whose hand is placed on the keyboard, the touch pad having a plurality of electrically conducting sector plates arranged about a central origin and electrically isolated from each other, the plates being covered by a dielectric layer which is exposed to the touch of the operator;
and
(b) means electrically connected to each of the sector plates for detecting the relative area of each of the sector plates covered by the operator's finger based on the change in capacitance of each sector plate which will be in proportion to the area of the sector plate that is covered by the operator's finger and calculating the relative X and Y positions of the area of contact of the operator's finger with respect to the origin of the touch pad based on the relative areas of each plate covered by the operator's finger, and for providing an output signal indicative thereof to the cursor control output of the keyboard.

Touch activated controlling apparatus comprising:

(a) a touch pad having a plurality of conductive plates arranged adjacent to and electrically isolated from one another and a thin dielectric layer covering the conductive plates such that a user touching the top surface of the dielectric layer will change the capacitance of each plate beneath the user's finger in proportion to the area of the plate covered by the finger;
(b) means electrically connected to each of the conductive plates for applying a pulse signal to each of the individual plates sequentially to charge and discharge the plates and providing an output signal indicative of the change in capacitance of each plate caused by the touch of the user as determined from the charging-discharging waveforms for each plate;
and
(c) means receiving the signal indicative of the change in capacitance of each of the plates for determining the relative position of the touch by a user on the touch pad based on the relative change in capacitance of each plate and a preselected orientation weighting factor assigned to each plate and for providing a signal indicative of the relative position of the user's touch on the touch pad.

1 more element

A method of determining the relative position of the portion of a user's finger which touches a touch pad having plural conductive segments arranged as electrically isolated sectors of a circle about an origin, comprising the steps of:

(a) individually supplying a pulse of electricity to each of the sectors of the touch pad;
(b) measuring the time of charge of each sector relative to a known capacitance, whereby the difference in the time of charge of each sector and the known capacitance will be proportional to the difference in capacitance between the conductive sector and the known capacitance;
(c) determining a number proportional to the relative time difference between the charging of each sector and the known capacitance;
(d) multiplying for each sector the number proportional to the change time times an X weighting factor and a Y weighting factor which are functions of the angular position of the sector with respect to the origin of the touch pad;
(e) adding the weighted X and Y sector values to determine a total X value and a total Y value which are indicative of the relative angular position of the contact of the user's finger on the touch pad with respect to the origin.

2 more elements

Dependencies are inferred from the claim text.

Touch activated control method and apparatus

Life of this patent

Touch activated control method and apparatus

Life of this patent

Abstract

Claims31