Method and apparatus for detecting defective traces in a mutual capacitance touch sensing device
First Claim
1. A method of testing a mutual capacitance sensing device, comprising:
- applying a drive signal to a first row or column of drive electrodes from among a plurality of drive electrodes arranged substantially parallel to one another;
measuring respective relative mutual capacitances generated by the drive signal using a plurality of columns or rows of sense electrodes which intersect the rows or columns of drive electrodes at an angle, the columns or rows of sense electrodes being arranged substantially parallel to one another;
associating the measured respective relative mutual capacitances with cells corresponding to intersecting drive and sense electrode locations;
determining differences between the measured relative capacitances of adjoining cells;
determining whether any of the differences exceed or fall below predetermined thresholds corresponding thereto, andidentifying one or more defective traces on the basis of the differences exceeding or falling below the predetermined thresholds.
3 Assignments
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Accused Products
Abstract
Several different methods of testing the integrity and proper operation of the drive and sense electrodes in a mutual capacitance sensing device such as a touchscreen or touchpad are disclosed herein. According to one embodiment, measured values of mutual capacitance corresponding to individual cells in a mutual capacitance sensing device are compared to one another and to predetermined thresholds. The results of the comparison are employed to determine whether any of the traces forming the electrodes in the device are defective. By way of example, traces can be defective if they are broken, too thin, too thick, or shorted together. The various embodiments of the methods disclosed herein may be used for touchscreen or touchpad quality control in a manufacturing setting, or may be used to test touchscreens or touchpads that have already been incorporated into electronic devices. The various methods disclosed herein lower manufacturing costs, increase product quality and yield, and may be carried out quickly.
20 Citations
41 Claims
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1. A method of testing a mutual capacitance sensing device, comprising:
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applying a drive signal to a first row or column of drive electrodes from among a plurality of drive electrodes arranged substantially parallel to one another; measuring respective relative mutual capacitances generated by the drive signal using a plurality of columns or rows of sense electrodes which intersect the rows or columns of drive electrodes at an angle, the columns or rows of sense electrodes being arranged substantially parallel to one another; associating the measured respective relative mutual capacitances with cells corresponding to intersecting drive and sense electrode locations; determining differences between the measured relative capacitances of adjoining cells; determining whether any of the differences exceed or fall below predetermined thresholds corresponding thereto, and identifying one or more defective traces on the basis of the differences exceeding or falling below the predetermined thresholds. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of testing a mutual capacitance sensing device for defective traces, comprising:
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applying a drive signal to a first row or column of drive electrodes; measuring, in at least first and second columns or rows of sense electrodes arranged at an angle with respect to the first row or column, first and second capacitances resulting from the drive signal being applied to the first row or column, the first and second columns and rows being arranged substantially parallel to one another; applying the drive signal to a second row or column of drive electrodes arranged substantially parallel to the first row or column; measuring, in the first and second columns or rows of sense electrodes, third and fourth capacitances resulting from the drive signal being applied to the second row or column, the first, second, third and fourth measured capacitances corresponding to respective first, second, third and fourth cells in the sensing device; determining, for adjoining cells, differences between measured capacitances, and determining whether any of the differences exceed or fall below predetermined thresholds corresponding to the first, second, third or fourth cells, thereby indicating the presence of one or more defective traces in or near such cells. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of testing a mutual capacitance sensing device for defective traces, comprising:
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applying a drive signal to a first row or column of drive electrodes; measuring a first capacitance resulting from the drive signal being applied to the first row or column of drive electrodes in a first column or row of sense electrodes forming an angle with respect to the first row or column; measuring a second capacitance resulting from the drive signal being applied to the first row or column of drive electrodes in a second column or row of sense electrodes arranged substantially parallel to the first column or row of sense electrodes; applying the drive signal to a second row or column of drive electrodes arranged substantially parallel to the first row or column of drive electrodes; measuring a third capacitance resulting from the drive signal being applied to the second row or column of drive electrodes in the first column or row of sense electrodes; measuring a fourth capacitance resulting from the drive signal being applied to the second row or column of drive electrodes in the second column or row of sense electrodes, the first, second, third and fourth measured capacitances corresponding to respective first, second, third and fourth cells in the sensing device, and comparing the first, second, third and fourth measured capacitances to predetermined thresholds corresponding thereto. - View Dependent Claims (39, 40)
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41. A method of testing a mutual capacitance touch sensing device, comprising:
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applying a drive signal to a first row or column of drive electrodes arranged substantially parallel to one another; sequentially measuring respective relative mutual capacitances generated by and corresponding to the drive signal using a plurality of columns or rows of sense electrodes which intersect the rows or columns of drive electrodes at an angle, the columns or rows of sense electrodes being arranged substantially parallel to one another; storing, in a computer readable medium, and associating with a processor, measured respective relative mutual capacitances with specific areas of the device; determining with the processor whether any of the determined relative capacitances associated with different portions of the device exceed or fall below a predetermined threshold; identifying one or more defective traces corresponding to one or more portions of the device associated with determined relative capacitances exceeding or falling below the threshold.
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Specification