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KR-102961119-B1 - CALIBRATION METHOD OF FINGERPRINT SENSOR AND DISPLAY DEVICE USING THE SAME

KR102961119B1KR 102961119 B1KR102961119 B1KR 102961119B1KR-102961119-B1

Abstract

A method for calibrating a fingerprint sensor comprises a substrate, a light-shielding layer disposed on a first surface of the substrate and including openings formed in a light-shielding mask, a light-emitting element layer disposed on the light-shielding layer and including a plurality of light-emitting elements, and a sensor layer disposed on a second surface of the substrate and including a plurality of light sensors, wherein the method includes the steps of generating correction data through white calibration and dark calibration, and applying an offset to the plurality of light sensors using the correction data.

Inventors

  • 김문수
  • 김기용
  • 신정훈
  • 조한수

Assignees

  • 삼성디스플레이 주식회사

Dates

Publication Date
20260507
Application Date
20191127

Claims (20)

  1. A method for calibrating a fingerprint sensor comprising: a substrate; a light-shielding layer disposed on a first surface of the substrate and including openings formed in a light-shielding mask; a light-emitting element layer disposed on the light-shielding layer and including a plurality of light-emitting elements; and a sensor layer disposed on a second surface of the substrate and including a plurality of light sensors. A step of generating correction data through white calibration and dark calibration; and The step of applying an offset to the plurality of optical sensors using the correction data; is included. The above white calibration includes first to third white calibration steps for measuring the amount of light received by the sensor layer for each of the first to third luminances of the light-emitting elements, and The above dark calibration includes first to third dark calibration steps for measuring the amount of light received by the sensor layer for each of the first to third brightness levels of the light-emitting elements, and A method for calibrating a fingerprint sensor in which the third brightness of the light-emitting elements is higher than the second brightness, and the second brightness is higher than the first brightness.
  2. In Article 1, A calibration method comprising the step of generating the above correction data, wherein a first reflector having a flat reflective surface is placed on a first surface of the substrate such that it overlaps with the sensor layer in the thickness direction.
  3. In Article 2, The first reflector includes a skin-colored reflector and a black reflector, and the white calibration step utilizes the skin-colored reflector. The above dark calibration is a calibration method using the above black reflector.
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  6. In Paragraph 3, A calibration method in which the light reception time of the sensor layer in the white calibration step is longer than the light reception time of the sensor layer in the dark calibration step.
  7. In Article 6, A calibration method in which the light reception time of the sensor layer in the first white calibration step is longer than the light reception time of the sensor layer in each of the second and third white calibration steps.
  8. In Article 7, The step of generating the correction data above includes: measuring the amount of light received by the sensor layer for each of the first to third white calibration steps and the first to third dark calibration steps; and A calibration method comprising the step of determining whether normal operation is achieved by checking whether the amount of light received by the sensor layer measured above falls within a preset range.
  9. In Article 8, A calibration method in which the above-mentioned pre-set range has an upper limit of a brightness value 400 greater than a reference brightness value and a lower limit of a brightness value 400 smaller than the reference brightness value for the amount of light received by the sensor layer.
  10. In Article 9, A calibration method comprising a panel driving unit that controls the brightness of the light-emitting elements.
  11. In Article 10, A calibration method further comprising the step of resetting the panel driving unit when the amount of light received by the sensor layer exceeds the preset range.
  12. In Article 11, A step of generating a test image for a second reflector having a curved reflective surface based on sensing signals provided from the light sensors; A step of detecting the shape of the curvature of the second reflector by performing correction on the test image using the correction data; and A calibration method further comprising a noise inspection step for determining whether the correction data generation is normal using the shape of the curvature of the second reflector.
  13. Substrate; A light-shielding layer disposed on one surface of the above substrate and comprising openings formed in a light-shielding mask; A circuit element layer having at least one conductive layer disposed on the light-blocking layer and having circuit elements disposed thereon; A light-emitting element layer disposed on the above circuit element layer and comprising light-emitting elements; A sensor layer disposed on the other side of the above substrate and comprising a plurality of optical sensors; A driving circuit comprising a panel driving unit that generates a first driving signal for controlling the light-emitting elements and a second driving signal for controlling the light sensors, and a fingerprint detection unit that detects a fingerprint based on sensing signals provided from the light sensors; and A memory for storing correction data generated through calibration; comprising, The above driving circuit is, A first fingerprint image is generated by capturing the fingerprint through the fingerprint detection unit, and When comparing the brightness value of the first fingerprint image and the correction data, if a difference exceeding a preset range occurs, the brightness of the light-emitting elements is adjusted through the panel driving unit. A second fingerprint is generated by re-imaging the fingerprint through the fingerprint detection unit above, and The above calibration generates correction data through a white calibration step and a dark calibration step, and The above white calibration includes first to third white calibration steps for measuring the amount of light received by the sensor layer for each of the first to third luminances of the light-emitting elements, and The above dark calibration includes first to third dark calibration steps for measuring the amount of light received by the sensor layer for each of the first to third brightness levels of the light-emitting elements, and A display device in which the third brightness of the light-emitting elements is higher than the second brightness, and the second brightness is higher than the first brightness.
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  15. In Article 13, A display device utilizing a first reflector having a flat reflective surface, which is disposed on a first surface of the substrate so as to overlap with the sensor layer in the thickness direction in the step of generating the above correction data.
  16. In Article 15, A display device wherein the first reflector includes a skin-colored reflector and a black reflector, the white calibration step uses the skin-colored reflector, and the dark calibration uses the black reflector.
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  19. In Article 16, A display device comprising the step of generating the above correction data, wherein for each step of the first to third white calibration step and the first to third dark calibration step, the amount of light received by the sensor layer is measured to determine whether it falls within a preset range and thereby determines whether normal operation is performed.
  20. In Article 19, A display device comprising the step of resetting the panel driving unit when the amount of light received by the sensor layer exceeds the preset range.

Description

Calibration method of fingerprint sensor and display device using the same The present invention relates to a method for calibrating a fingerprint sensor and a display device using the same. A display device is a device for displaying images and includes display panels such as organic light-emitting display panels or liquid crystal display panels. An Organic Light Emitting Diode Display (OLED display) is a type of self-emissive display. An OLED includes an organic light-emitting layer interposed between a pixel electrode and a counter electrode. When the two electrodes each inject electrons and holes into the organic light-emitting layer, excitons are generated through the combination of electrons and holes, and light is emitted as these excitons fall from the excited state to the ground state. The display device may include a fingerprint sensor for fingerprint sensing. A light-sensing fingerprint sensor may be equipped with a light source and a light sensor. The light sensor receives reflected light generated by the user's fingerprint, and the fingerprint detection unit can detect the fingerprint by generating and processing an original image based on the reflected light. The reflected light received by the optical sensor may contain noise, or the original image may contain noise (or error) due to deviations in the optical sensor (and optical path). To remove noise from the original image, the fingerprint detection unit may perform calibration on the original image. FIG. 1 is a drawing for explaining a preliminary calibration device for a fingerprint sensor according to one embodiment of the present invention. FIGS. 2 and FIGS. 3 are schematic plan views illustrating a display module according to an embodiment of the present invention. FIG. 4 is a plan view showing various embodiments of the arrangement structure of pixels and light sensors. FIG. 5 is a schematic cross-sectional view of a display panel according to one embodiment of the present invention. FIG. 6 is a plan view showing one embodiment of a light-blocking layer. FIG. 7 is a block diagram showing the configuration of a fingerprint detection unit according to one embodiment of the present invention. Figure 8 is a flowchart illustrating a preliminary calibration method for a fingerprint sensor. Figure 9 is a graph showing the amount of light received by the fingerprint sensor measured in sections of white calibration and dark calibration. Figures 10 and 11 are drawings for explaining the pixel-by-pixel deviation and offset application of a fingerprint sensor. FIG. 12 is a graph showing correction data according to one embodiment of the present invention. FIG. 13 is a flowchart illustrating a method for detecting and correcting malfunctions while performing preliminary calibration of a fingerprint sensor. FIG. 14 is a flowchart for explaining a calibration method of a display device according to one embodiment of the present invention. Identical reference numerals denote identical components. Additionally, in the drawings, the thicknesses, proportions, and dimensions of the components are exaggerated for the effective illustration of the technical content. "And/or" includes all one or more combinations that the associated components may define. Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. A singular expression includes a plural expression unless the context clearly indicates otherwise. Additionally, terms such as "below," "lower side," "above," and "upper side" are used to describe the relationships between the components depicted in the drawings. These terms are relative concepts and are described based on the directions indicated in the drawings. Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof. FIG. 1 is a drawing for explaining a preliminary calibration device for a fingerprint sensor according to an embodiment of the present invention. FIG. 2 and FIG. 3 are schematic drawings showing a display module according to an embodiment of the present invention. Referring to FIGS. 1 to 3, the preliminary calibration device (1) of the fingerprint sensor may include a jig (JG) and a reflector (RUB) for performing preliminary calibration for the fingerprint sensor (FS) of the display module (DM). According to one embodiment, the jig (JG) may include a stage (ST) that supports a