System and method for a projected capacitive touchscreen having weight based coordinate determination

• US 8,477,106 B2
• Filed: 07/29/2009
• Issued: 07/02/2013
• Est. Priority Date: 07/29/2009
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touch Solutions, Inc.
• Inventors: Salaverry, Ricardo R., Kent, Joel C., Aroyan, James L.
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): MA, CALVIN
• Application Number:
  US12/511,449
• Publication Number:
  US 20110025638A1
• Time in Patent Office: 1,434 Days
• Field of Search: 345/173, 345/174, 178/18.05, 178/18.06, 324/678
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

A touch location on a capacitive touchscreen system is identified by receiving signals in response to a touch from electronic channels connected to one electrode or to a group of semi-adjacent electrodes provided on a substrate. Adjacent ones of the electrodes have substantially triangular shapes that alternate between a first and second orientation to form an interleaved arrangement such that the touch generates a signal cluster comprising the signals generated from a series of adjacent electronic channels. Weights with at least two different numerical values are applied to the signals from the series of adjacent electronic channels. The at least two different numerical values are based on levels of the signals. A location of the touch on the substrate is determined based on the weighted signals.

Claims

1. A capacitive touchscreen system, comprising:

a substrate comprising a touch sensitive area;

electrodes provided on the substrate within the touch sensitive area, the electrodes having substantially triangular shapes, the electrodes being interlaced with one another in a non-overlapping pattern on the substrate, the electrodes each having a longitudinal axis that defines a coordinate axis parallel to the longitudinal axis, the electrodes configured to generate corresponding signals in response to a touch on the substrate;

a controller; and

electronic channels within the controller, each of the electronic channels being connected to one electrode or to a group of semi-adjacent electrodes, the controller configured to detect the signals from the electronic channels and to identify a signal cluster comprising the signals from a series of at least two adjacent electronic channels, the controller identifying a first electronic channel within the series that has a local maximum signal, the controller applying a first weight with a first numerical value to a first signal from the first electronic channel that has the local maximum signal to generate a first weighted signal and applying a second weight with a second numerical value to a second signal from a second electronic channel within the series to generate a second weighted signal, the first numerical value being different than the second numerical value, the controller determining a location of the touch along the coordinate axis based on the first weighted signal and the second weighted signal.

2. The system of claim 1, wherein the controller is further configured to to apply a third weight with a relatively smaller numerical value than the second weight to a third signal from a third electronic channel within the series that is relatively further from the first electronic channel that has the local maximum signal than the second electronic channel.

3. The system of claim 1, wherein the controller is further configured to identify the series by identifying adjacent electronic channels that have signals that are above a signal threshold.

4. The system of claim 1, wherein the first numerical value is larger than the second numerical value.

5. The system of claim 1, wherein the controller is further configured to apply the second weight with the second numerical value to at least one of the electronic channels within the series that are located on either side of the first electronic channel with the local maximum signal, and wherein the controller is further configured to apply a third weight with a third numerical value to a signal of at least one other of the electronic channels within the series, wherein the first numerical value is larger than the second numerical value and the second numerical value is larger than the third numerical value.

6. The system of claim 1, wherein the controller is further configured to apply the first weight with the first numerical value to a signal of at least one of the electronic channels within the series that is adjacent to the first electronic channel with the local maximum signal.

7. The system of claim 1, wherein the controller is further configured to apply a third weight with a numerical value of approximately zero to signals from the electronic channels within the series that have signal levels below a signal threshold.

8. The system of claim 1, wherein the signal cluster further comprises signals from a series of at least three adjacent electronic channels, wherein the first numerical value is larger than the second numerical value, and wherein the second weight with the second numerical value is applied to electronic channels that are located on either side of the first electronic channel that has the local maximum signal.

9. The system of claim 1, wherein the first numerical value is approximately zero and the second numerical value is greater than the first numerical value.

10. The system of claim 1, wherein the first numerical value is approximately twice as large as the second numerical value.

11. The system of claim 1, wherein the first and second numerical values are determined based on binomial weighting.

12. The system of claim 1, wherein at least a portion of the electrodes are electrically connected into groups of at least three semi-adjacent electrodes, the controller configured to detect one signal from each of the groups of at least three semi-adjacent electrodes.

13. A method for identifying a touch location on a capacitive touchscreen system, comprising:

receiving signals in response to a touch from electronic channels that are each connected to one electrode or to a group of semi-adjacent electrodes of electrodes provided on a substrate, adjacent ones of the electrodes having substantially triangular shapes that alternate between a first and second orientation to form an interleaved arrangement such that the touch generates a signal cluster comprising the signals generated from a series of adjacent electronic channels, the electrodes each having a longitudinal axis that defines a coordinate axis parallel to the longitudinal axis;

applying weights with at least two different numerical values to the signals from the series of adjacent electronic channels to generate weighted signals, the at least two different numerical values being based on levels of the signals from the series of adjacent electronic channels; and

determining a location of the touch on the substrate along the coordinate axis based on the weighted signals.

14. The method of claim 13, wherein the applying weights further comprises applying a first weight with a smaller numerical value to a first signal from a first electronic channel within the series that has a maximum signal level and applying a second weight with a larger numerical value to a second signal from a second electronic channel within the series that has a signal level that is less than the maximum signal level.

15. The method of claim 13, wherein the applying weights further comprises applying a first set of weights having a first set of numerical values to at least a first portion of first electrodes within the series that have the first orientation and applying a second set of weights having a second set of numerical values to at least a second portion of second electrodes within the series that have the second orientation, and wherein the sums of first and second sets of numerical values are substantially the same.

16. The method of claim 13, wherein the weights with at least two different numerical values comprises a first set of weights, the method further comprising:

applying a second set of weights with at least two different numerical values to the signals from the series of electronic channels to generate second weighted signals, the second set of weights being different than the first set of weights; and

further determining the location along the coordinate axis based on an average of the weighted signals based on the first set of weights and the second weighted signals based on the second set of weights.

17. The method of claim 13, further comprising:

comparing levels of the signals from the electronic channels within the series to a signal threshold; and

selecting the numerical values of the weights based on the comparison.

18. The method of claim 13, further comprising:

identifying an electronic channel from the series of adjacent electronic channels that has a maximum signal; and

discarding the signals from the electronic channels within the series of adjacent electronic channels when a level of signals from two electronic channels that are adjacent to the electronic channel that has the maximum signal are less than a signal threshold.

19. The method of claim 13, further comprising:

identifying an electronic channel from the series of adjacent electronic channels that has a maximum signal level with respect to levels of signals from other electronic channels within the series;

comparing the levels of the signals from the other electronic channels from within the series to at least one signal threshold; and

determining the at least two different numerical values of the weights based on the comparison.

20. The method of claim 13, further comprising:

receiving second signals in response to a second touch that generates a second signal cluster comprising signals generated from a second series of adjacent electronic channels that is distinct from the series of adjacent electronic channels generating the signal cluster, the second signal cluster being detected simultaneously with the signal cluster;

applying weights with at least two different numerical values to the second signals associated with the second signal cluster to generate second weighted signals; and

determining a location of the second touch on the substrate along the coordinate axis based on at least the second weighted signals associated with the second touch.