Touch terminal with reliable pad selection

• US 4,374,381 A
• Filed: 05/01/1981
• Issued: 02/15/1983
• Est. Priority Date: 07/18/1980
• Status: Expired due to Fees

• Current Assignee: Interaction Systems Incorporated (Computer Library Systems, Inc.)
• Original Assignee: Interaction Systems Incorporated (Computer Library Systems, Inc.)
• Inventors: Ng, Henry H., Schmidt, Frederick R.
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Crosland, Donnie L.
• Application Number:
  US06/259,614
• Time in Patent Office: 655 Days
• Field of Search: 340/365 C, 340/365 E, 340/365 S, 340/365 R, 340/712, 340/711, 340/365 UL, 340/802, 200/DIG. 1, 178/17 C
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment

Abstract

A touch terminal identifies a single user-selectable, touch-responsive pad element on the display screen for user communication with a data processing system. The terminal makes the identification in response to the durations of pulse signals which vary according to the touch-selection condition of the pad elements. A multiple-step technique of repetitively measuring the signal durations relative to reference values attains essentially error-free pad selection. The operation includes the updating of the reference values of the pulse-signal durations.

Claims

1. In a display touch terminal having plural user-selectable, touch-responsive pad elements on a display screen for user communication with a data processing system, the improvement comprising

A. means in circuit with said pad elements for producing a sequence of pulse signals with pulse signal durations responsive to the touch-selection condition of any selected pad element,

B. pulse measuring means in circuit with said means for producing for measuring said pulse signal durations a selected multiple of times for any selected pad element,

C. compare means in circuit with said measuring means for determining a difference in pulse signal duration between said multiple duration measures and a reference duration for said single pad element, and

D. means for identifying a single pad element as user selected in response to a selected comparison determination from at least some of said multiple duration measures.

2. In a touch terminal according to claim 1, the further improvement

A. comprising means for selecting, from among at least some of said multiple duration measures for each pad element, the measures having a selected extreme value, and

B. in which said compare means determines said difference in response to said extreme-valued measures and said reference duration.

3. In a touch terminal according to claim 1 having a cathode ray tube display device and having display control means which repetitively sweep an electron beam horizontally across the cathode ray tube screen, the further improvement comprising means for restricting the identification of a single pad element as user selected only to measures of pulse signal duration during the horizontal sweep of the cathode ray tube display device.

4. In a touch terminal according to claim 1, the further improvement comprising

A. means for storing a measure of reference duration for each pad element and in circuit with said compare means,

B. means for determining when no pad element among a selected plurality thereof is user selected, and

C. means for replacing in said storing means the reference duration for any pad element in response to said multiple duration measure for that pad element when no pad element on the screen is selected.

5. In a touch terminal according to claim 1, the further improvement in which said pulse measuring means includes

clock means for producing a sequence of selectively-timed signals, and

counter means in circuit with said pulse signal producing means and with said clock means for counting said selectively-timed clock signals for a duration responsive to said pulse signal durations.

6. In a display touch terminal having plural user-selected, touch-responsive pad elements on a display screen for user communication with a data processing system, the improvement comprising

A. means in circuit with said pad elements for producing a sequence of pulse signals with pulse signal durations responsive to the touch-selection condition of any selected pad element,

B. means in circuit with said producing means for measuring a first plurality of times the durations of the pulse signals responsive to the touch condition of each of said pad elements,

C. means responsive to said measuring means for storing an identification of each pad element for which the measured pulse durations exceed a reference value for that pad element by a selected measure,

D. means for measuring a second plurality of times the duration of the pulse signals responsive to the touch condition of each of said identified pad elements, and

E. means in circuit with said last-named measuring means for identifying as user selected the single identified pad element for which the second plurality of measured pulse durations exceeds the reference value for that pad element by a selected measure.

7. A display touch terminal having plural user-selected, touch-responsive pad elements on a display screen for user communication with a data processing system, said terminal having the improvement comprising

A. means in circuit with said pad elements for producing a sequence of pulse signals with pulse signal durations responsive to the touch selection condition of any single pad element,

B. means connected for receiving said pulse signals for repetitively measuring said pulse signal durations a first plurality of times for the same single addressed pad element,

C. means connected for receiving said duration measures for selecting, from among each of said first plurality of duration measures for a single pad element, the one measure having a selected extreme value,

D. means responsive to said measuring means for storing an identification of a pad element for which said repetitive number of said extreme-valued duration measures exceeds a selected measure relative to a reference duration for that same pad element,

E. means for providing a measurement of said pulse signal durations a second plurality of times for each identified pad element and for selecting, from among said second plurality of duration measures for each identified pad element, the one measure having a selected extreme value, and

F. means for identifying an addressed pad element as being user selected in response to said latter selection.

8. Touch terminal apparatus for use with a display device for identifying which location on a display screen a user touches, said apparatus having user-selectable, touch-responsive pad elements on the screen and further comprising

A. address means for addressing any pad element,

B. means in circuit with said pad elements for producing a sequence of pulse signals with pulse signal durations responsive to the touch selection condition of any addressed pad element,

C. pulse-measuring means responsive to said pulse signals for measuring said pulse signal durations a selected multiple of times for the same addressed pad element,

D. compare means responsive to said measured durations for determining a difference in pulse duration between said multiple duration measures for an addressed pad element and a reference duration for said addressed pad element, and

E. means for identifying a pad element as user selected in response to a comparison measure for that pad element in excess of a selected measure by more than the corresponding measure for any other pad element.

9. Touch terminal apparatus according to claim 8, further comprising

A. means for storing information identifying a pulse-signal reference duration for each pad element and in circuit with said compare means,

B. means for determining the absence of a reference-exceeding comparison measure for any pad element among at least a selected portion of all the pad elements on the display screen, and

C. means in circuit with said storing means and responsive to said absence-determining means for selectively replacing a stored reference duration for an addressed pad element with a measure identified by said multiple duration measures for that addressed pad element in response to said absence determination.

10. Touch terminal apparatus for use with a display device for identifying the location on a display screen which a user touches and having user-selectable, touch-responsive pad elements on the screen, said apparatus further comprising

A. means in circuit with said pad elements for producing pulse signals with pulse signal durations responsive to the touch-selection condition of any pad element,

B. pulse measuring means responsive to said pulse signals for measuring said pulse signal durations for any pad element,

C. means for storing a measure of a reference duration for each pad element,

D. means connected with said measuring means and said storing means for identifying a pad element as user selected in response to a selected comparison between said duration measure and a reference duration for said pad element,

E. means for selectively replacing in said storing means the reference duration for any pad element in response to said duration measure for that pad element, and

F. means for disabling the reference replacement when any pad element is identified as being touched.