An optical-fingerprint detection system has received a technical patent from the USPTO. The temperature compensation approach can be implemented using a row-based system. In the row-based technique, the first reading is obtained while the matching pixel switches are open, and one or more of the array’s pixels are pixels of a row of the array. While the corresponding pixel switches are closed, the second reading is obtained.
In one or more implementations, the temperature adjustment approach uses a blind pixel scheme. Blind pixels are those in one or more array columns protected from optical exposure. In the blind pixel approach, the first reading is taken for blind pixels using a first-row-based double sampling, while the second reading is acquired for exposed pixels using a second-row-based double sampling.
One or more full pixels from the array are included in the one or more pixels of the temperature correction mechanism in some frame-based implementations. Using a first frame-based double sampling, this approach obtains the first reading while the array is not lighted. The second reading is obtained while the array is illuminated using a second frame-based double sampling. The row-based scheme, the blind scheme, and the frame-based scheme are all used in conjunction with the temperature compensation method in one or more implementations. The optical-fingerprint detection system in the granted patent may be especially helpful for identification and/or verification in a portable device.
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