Calibration method for fingerprint sensor and display device using the same

1. A display device, comprising:

a substrate;

a light-blocking layer located on a first surface of the substrate and having openings formed in a light-blocking mask;

a circuit-element layer located on the light-blocking layer and having at least one conductive layer in which circuit elements are located;

a light-emitting element layer located on the circuit-element layer and having light-emitting elements;

a sensor layer located on a second surface of the substrate and having a plurality of photosensors;

a driving circuit comprising a panel driver configured to generate a first driving signal for controlling the light-emitting elements and a second driving signal for controlling the photosensors, and a fingerprint detector configured to detect a fingerprint based on sensing signals provided from the photosensors; and

a memory configured to store calibration data generated through calibration,

wherein the driving circuit is configured to:

generate a first fingerprint image by capturing an image of the fingerprint through the fingerprint detector,

compare a brightness value of the first fingerprint image with the calibration data, and adjust brightness values of the light-emitting elements through the panel driver when a difference between the brightness values of the first fingerprint image and the calibration data is outside of a preset range, and

generate a second fingerprint image by re-capturing an image of the fingerprint through the fingerprint detector.

2. The display device according to claim 1 , wherein the calibration is configured to generate the calibration data through white calibration and dark calibration.

3. The display device according to claim 1 , wherein the calibration data is generated using a first reflector located on the first surface of the substrate to overlap the sensor layer in a thickness direction and configured to have a flat reflective surface.

4. The display device according to claim 3 , wherein:

the first reflector comprises a skin color reflector and a black reflector, and

the white calibration is performed using the skin color reflector, and the dark calibration is performed using the black reflector.

5. The display device according to claim 2 , wherein:

the white calibration comprises first, second and third white calibration operations of measuring received light amounts of the sensor layer corresponding to first, second and third brightness values of the light-emitting elements, respectively, and

the dark calibration comprises first, second and third dark calibration operations of measuring received light amounts of the sensor layer corresponding to the first, second and third brightness values of the light-emitting elements, respectively.

6. The display device according to claim 5 , wherein the third brightness value of the light-emitting elements is higher than the second brightness value, and the second brightness value is higher than the first brightness value.

7. The display device according to claim 4 , wherein the calibration data is generated by measuring a received light amount of the sensor layer in each of the first, second and third white calibration operations and in each of the first, second and third dark calibration operations, checking whether the measured received light amount of the sensor layer is within a preset range, and then determining whether a corresponding calibration operation is a normal operation.

8. The display device according to claim 7 , wherein the driver is reset when the received light amount of the sensor layer is outside of the preset range.