Determining leakage in matrix-structured electronic devices
View Patent ↗One embodiment of this invention pertains to a high throughput screening technique to identify current leakage in matrix-structured electronic devices. Because elements that are likely to develop a short have relatively high leakage current at zero operation hours, by identifying elements with the relatively high leakage current, the electronic devices that are more likely to later develop a short can be differentiated. The screening technique includes performing the following actions: selecting one of multiple first lines; applying a first voltage to the selected first line; applying a second voltage to the one or more of the first lines that are not selected; floating the multiple second lines; and measuring the voltages on the second lines, either sequentially one line at a time or measuring all the lines at the same time.
1. A method to detect leaky elements in a matrix-structured electronic device, wherein said device includes a plurality of elements, a plurality of first lines, and a plurality of second lines, wherein said plurality of first lines intersect said plurality of second lines, and said plurality of elements are at said intersections and are coupled to said plurality of first lines and said plurality of second lines, said method comprising:
(a) selecting a particular one of said plurality of first lines;
(b) applying a first voltage to said particular first line that is selected;
(c) applying a second voltage to one or more of said plurality of first lines that are not selected;
(d) floating said plurality of second lines; and
(e) measuring a plurality of voltages on said plurality of second lines, each of said plural measured voltages identifying a particular one of said plural elements which is coupled to both a corresponding selected first line and the corresponding second line.
2. The method of claim 1 further comprising
(f) assigning said plurality of voltages to corresponding ones of said plurality of elements that are at intersections of said selected first line and said plurality of second lines.
3. The method of claim 1 wherein said first voltage is significantly lower than said second voltage.
4. The method of claim 1 wherein said first voltage is 0V and said second voltage is greater than 6V.
5. The method of claim 1 wherein said matrix-structured electronic device is an OLED display, and said plurality of elements is a plurality of pixels.
6. A method to detect leaky elements in a matrix-structured electronic device, wherein said device includes a plurality of elements, a plurality of first lines, and a plurality of second lines, wherein said plurality of first lines intersect said plurality of second lines, and said plurality of elements are at said intersections and are coupled to said plurality of first lines and said plurality of second lines, said method comprising:
(a) selecting a particular one of said plurality of first lines;
(b) applying a first voltage to said particular first line that is selected;
(c) applying a second voltage to one or more of said plurality of first lines that are not selected;
(d) floating said plurality of second lines;
(e) measuring a plurality of voltages on said plurality of second lines;
(f) assigning said plurality of voltages to corresponding ones of said plurality of elements that are at intersections of said selected first line and said plurality of second lines; and
performing steps (a) thru (f) for each of remaining first lines of said plurality of first lines so that all of said plurality of first lines are selected once in part (a).
7. The method of claim 6 further comprising identifying one or more of said plurality of elements that are leaky elements.
8. The method of claim 7 wherein identifying said one or more leaky elements includes
(h) for a particular one of said plurality of second lines, determining a particular one of said plurality of elements coupled to said particular second line that has a corresponding one of said plurality of voltages that is a lowest voltage value;
(i) determining an average column voltage by;
(i) summing said plurality of voltages corresponding to those elements coupled to said particular second line but excluding said particular element having said lowest voltage value;
(ii) determining a number of said plurality of elements coupled to said particular second line but excluding said particular element having said lowest voltage value;
(iii) dividing said summed voltage value by said number to calculate said average column voltage;
(j) determining if said average column voltage is significantly greater than a particular one of said plurality of voltages corresponding to a particular one of said plurality of elements coupled to said particular second line; and
(k) if said average column voltage is significantly higher than a particular one of said plurality of voltages corresponding to a particular one of said plurality of elements coupled to said particular second line, then identifying said particular element as one of said one or more leaky elements.
9. The method of claim 8 further comprising
(l) performing parts (j) that (k) for each of remaining elements of said plurality of elements coupled to said particular second line so that all of said plurality of elements coupled to said particular second line are selected once.
10. The method of claim 9 further comprising performing parts (h) thru (l) for each of remaining second lines of said plurality of second lines so that all of said plurality of second lines are selected once.
11. The method of claim 6 further comprising indicating whether said matrix-structured electronic device includes at least one leaky element by
for a particular one of said plurality of second lines, determining a particular one of said plurality of elements coupled to said particular second line that has a corresponding one of said plurality of voltages that is a lowest voltage value;
determining an average column voltage by:
summing said plurality of voltages corresponding to those elements coupled to said particular second line but excluding said particular element having said lowest voltage value;
determining a number of said plurality of elements coupled to said particular second line but excluding said particular element having said lowest voltage value;
dividing said summed voltage value by said number to calculate said average column voltage;
determining if said average column voltage is significantly greater than a particular one of said plurality of voltages corresponding to a particular one of said plurality of elements coupled to said particular second line; and
if said average colunm voltage is significantly higher than a particular one of said plurality of voltages corresponding to a particular one of said plurality of elements coupled to said particular second line, then indicating that said matrix-structured electronic device includes at least one leaky pixel.
12. The method of claim 8 wherein said average column voltage is significantly higher than said particular element voltage if said average column voltage is higher than said particular element voltage by at least 0.1V.
13. The method of claim 7 wherein identifying said one or more leaky elements includes for a particular one of said plurality of second lines, determining a voltage difference between a particular one of said plurality of voltages corresponding to a particular one of said plurality of elements coupled to said particular second line and another one of said plurality of voltages corresponding to another one of said plurality of elements that is adjacent to said particular element and is also coupled to said particular second line.
14. The method of claim 13 wherein said other one of said plurality of elements that is adjacent to said particular element is a particular one of said plurality of elements that is coupled to said particular second line and is adjacent to and immediately precedes said particular element, and
(o) wherein said voltage difference is determined between said particular one of said plurality of elements coupled to said particular second line and said particular one of said plurality of elements that is coupled to said particular second line and is adjacent to and immediately precedes said particular element; and
further comprising
(p) if said voltage difference between said particular voltage and said other voltage is a significant negative voltage difference, then identifying said particular element as one of said one or more leaky elements, otherwise, if said voltage difference is a significant positive voltage difference, then identifying said immediately preceding element that is adjacent to said particular element as one of said one or more leaky elements.
15. The method of claim 14 further comprising
(q) excluding a particular one of said plurality of elements coupled to said particular second line that is a first element of said particular second line, performing parts (o) and (p) for all other remaining elements of said plurality of elements that are coupled to said particular second line.
16. The method of claim 15 further comprising
performing part (q) for each of remaining second lines of said plurality of second lines so that said voltage difference is determined for elements coupled to all of said plurality of second lines.
17. The method of claim 6 further comprising indicating whether said matrix-structured electronic device includes at least one leaky element by
for a particular one of said plurality of second lines, determining a voltage difference between a particular one of said plurality of voltages corresponding to a particular one of said plurality of elements coupled to said particular second line and another one of said plurality of voltages corresponding to another one of said plurality of elements that is coupled to said particular second line and is adjacent to and immediately precedes said particular element; and
if said voltage difference between said particular voltage and said other voltage is a significant voltage difference, then indicating that said matrix-structured electronic device includes at least one leaky element.
18. The method of claim 14 wherein said significant negative voltage difference is at least −0.1V, and said significant positive voltage difference is at least 0.1V.
19. The method of claim 6 wherein said first voltage is significantly lower than said second voltage.
20. The method of claim 6 wherein said first voltage is 0V and said second voltage is greater than 6V.
21. The method of claim 6 wherein said matrix-structured electronic device is an OLED display, and said plurality of elements is a plurality of pixels.