In early June Patently Apple posted a report titled "Samsung files a patent addressing OLED Burn-In issues Specifically aimed at Smartphones with Under-Display Fingerprint ID." While burn-in has been a minor issue on smartphones, even Apple has warned of this issue. With Touch ID under the display, the issue could be more pronounced. Apple's patent pending solution published today by the U.S. Patent Office relates to Fingerprint ID under the display and a two-step method so as to control the temperature of the display in the Touch ID area.
Apple notes that fingerprint sensing and matching is widely used as a reliable technique for personal identification or verification. In particular, a common approach to fingerprint identification involves scanning a sample fingerprint of a person to form an image and storing the image as a unique characteristic of the person. The characteristics of the sample fingerprint may be compared to information associated with reference fingerprints already stored in a database to determine proper identification of the person, such as for verification purposes.
An optical fingerprint sensor may be particularly advantageous for verification and/or authentication in an electronic device and, more particularly, a portable device, for example, a portable communication device. The optical fingerprint sensor may be carried by the housing of a portable communication device, for example, and may be sized to sense a fingerprint from a single finger. Where an optical fingerprint sensor is integrated into an electronic device or host device, for example, as noted above, the authentication can be performed quickly, for example, by a processor of the host device.
The optical fingerprint sensor can, for example, be an organic optical detector (OPD) imager such as a thin-film-transistor-based (TFT-based) OPD imager, a PIN diode-based photodetector, and/or another photodetector. A TFT-based OPD imager is an OPD imager that is fabricated on a TFT-based electronic readout backplane.
An OPD imager can be an array of organic semiconductor photodiodes arranged in multiple (N) rows and multiple (e.g., M) columns. Each row of the OPD imager can be read out with a multi-channel analog front-end (AFE) circuit, where the number of channels is equal to the number of columns (e.g., M) of the OPD imager. Each channel of the AFE circuit reads a charge associated with a pixel (e.g., an OPD).
In one or more aspects, the subject technology is directed to methods and configuration for temperature compensation in an optical-fingerprint detection system.
The method includes acquiring a first reading associated with one or more pixels of an array, the first reading is a baseline reading. The method further includes acquiring a second reading associated with the one or more pixels of the array. The second reading includes the baseline plus a signal. A temperature compensated signal reading can be produced by subtracting the first reading from the second reading. The array includes an optical-fingerprint array, and each pixel of the array is coupled to a readout circuit via a pixel switch.
Apple's patent FIG. 10 below is a flow diagram illustrating an example method #1000 of temperature compensation in an optical-fingerprint detection system; FIG. 11 is a block diagram illustrating a wireless communication device (iPhone #1100), within which one or more aspects of the subject technology can be implemented. In one or more implementations, the device (an iPhone or Apple Watch) hosts an apparatus of the subject technology including an optical-fingerprint detection system.
Apple's patent application that was published today by the U.S. Patent Office was filed back in Q4 2019. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
Moe Yeke Yazdandoost: Tech Lead – Sensing Systems Architect
Chris Krah: Senior Hardware Engineer