Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors
This paper proposes a new architecture for a micro light emitting diode (micro-LED) display featuring fingerprint detection without any additional light emitting and sensing devices in mobile applications. This paper proposes that conventional LEDs can be used as photodetectors in active-matrix pixe...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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IEEE
2022-01-01
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| Series: | IEEE Access |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/9828388/ |
| _version_ | 1811296081800069120 |
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| author | Dong-Hwan Jeon Won-Been Jeong Hoon-Ju Chung Seung-Woo Lee |
| author_facet | Dong-Hwan Jeon Won-Been Jeong Hoon-Ju Chung Seung-Woo Lee |
| author_sort | Dong-Hwan Jeon |
| collection | DOAJ |
| description | This paper proposes a new architecture for a micro light emitting diode (micro-LED) display featuring fingerprint detection without any additional light emitting and sensing devices in mobile applications. This paper proposes that conventional LEDs can be used as photodetectors in active-matrix pixel circuits. In the area where a finger touched, some LEDs are used as photodetectors and others are used as light emitting sources. The photocurrents of reverse-biased LEDs under various illumination conditions were investigated. The active-matrix circuit was fabricated using a conventional p-type low-temperature polycrystalline silicon (LTPS) process. The fabricated pixel circuit could distinguish the intensity of the incident light to the sensing LED. The voltage across the sensing LED (V<sub>LED</sub>) was investigated when the pixel density was 400 pixels per inch (ppi) and the cover glass thickness was <inline-formula> <tex-math notation="LaTeX">$30 ~\mu \text{m}$ </tex-math></inline-formula>. The experimental results showed that the V<sub>LED</sub> changed by 0.5 V for 16.7 ms when red, green, or blue LEDs emitted 150 cd/m<sup>2</sup>, 400 cd/m<sup>2</sup>, or 100 cd/m<sup>2</sup>, respectively. <inline-formula> <tex-math notation="LaTeX">$1\times 9$ </tex-math></inline-formula> LED array with 1.5 mm pitch (p) and 2 mm thick cover glass was fabricated to emulate the LED display with 400 ppi and <inline-formula> <tex-math notation="LaTeX">$30 ~\mu \text{m}$ </tex-math></inline-formula> thick cover glass. It is found that an emitting LED affected the sensing LEDs within the distance of 3p by comparing V<sub>LED</sub>3. V<sub>LED</sub>3 were measured when the material on the cover glass was air and water with white pigments (water/W). <inline-formula> <tex-math notation="LaTeX">$\Delta \mathrm {V} _{\mathrm {LED}}\text{s}$ </tex-math></inline-formula> were 0.29 V and 1.13 V for glass-air and glass-water/W cases, respectively. It is found that the lights incident on the sensing LED comprised not only reflected lights by Fresnel reflection at the glass interface but also scattered lights in the water/W. A <inline-formula> <tex-math notation="LaTeX">$75\times $ </tex-math></inline-formula> magnified fake fingerprint was fabricated. Its material was poly-lactic acid with refractive index of 1.465 which is very close to that of a fingertip. Measured <inline-formula> <tex-math notation="LaTeX">$\Delta \mathrm {V}_{\mathrm {LED}}\text{s}$ </tex-math></inline-formula> at ridges and valleys were 0.48 V and 0.22 V, respectively. The ratio of 0.48/0.22 was 2.18 that is very close to 1.91 that is the ratio of light intensity at the ridge to that at the valley obtained by the calculation. This verifies that the proposed micro-LED display distinguishes the ridges and valleys of fingerprint without any help from any additional devices. |
| first_indexed | 2024-04-13T05:43:02Z |
| format | Article |
| id | doaj.art-7929cb3c62b948f2a82107fc09c5c443 |
| institution | Directory Open Access Journal |
| issn | 2169-3536 |
| language | English |
| last_indexed | 2024-04-13T05:43:02Z |
| publishDate | 2022-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Access |
| spelling | doaj.art-7929cb3c62b948f2a82107fc09c5c4432022-12-22T03:00:02ZengIEEEIEEE Access2169-35362022-01-0110741877419710.1109/ACCESS.2022.31906089828388Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional SensorsDong-Hwan Jeon0https://orcid.org/0000-0001-5692-0250Won-Been Jeong1Hoon-Ju Chung2https://orcid.org/0000-0001-9976-6281Seung-Woo Lee3https://orcid.org/0000-0002-6657-9225Department of Information Display, Kyung Hee University, Seoul, South KoreaDepartment of Information Display, Kyung Hee University, Seoul, South KoreaSchool of Electronic Engineering, Kumoh National Institute of Technology, Gumi-si, South KoreaDepartment of Information Display, Kyung Hee University, Seoul, South KoreaThis paper proposes a new architecture for a micro light emitting diode (micro-LED) display featuring fingerprint detection without any additional light emitting and sensing devices in mobile applications. This paper proposes that conventional LEDs can be used as photodetectors in active-matrix pixel circuits. In the area where a finger touched, some LEDs are used as photodetectors and others are used as light emitting sources. The photocurrents of reverse-biased LEDs under various illumination conditions were investigated. The active-matrix circuit was fabricated using a conventional p-type low-temperature polycrystalline silicon (LTPS) process. The fabricated pixel circuit could distinguish the intensity of the incident light to the sensing LED. The voltage across the sensing LED (V<sub>LED</sub>) was investigated when the pixel density was 400 pixels per inch (ppi) and the cover glass thickness was <inline-formula> <tex-math notation="LaTeX">$30 ~\mu \text{m}$ </tex-math></inline-formula>. The experimental results showed that the V<sub>LED</sub> changed by 0.5 V for 16.7 ms when red, green, or blue LEDs emitted 150 cd/m<sup>2</sup>, 400 cd/m<sup>2</sup>, or 100 cd/m<sup>2</sup>, respectively. <inline-formula> <tex-math notation="LaTeX">$1\times 9$ </tex-math></inline-formula> LED array with 1.5 mm pitch (p) and 2 mm thick cover glass was fabricated to emulate the LED display with 400 ppi and <inline-formula> <tex-math notation="LaTeX">$30 ~\mu \text{m}$ </tex-math></inline-formula> thick cover glass. It is found that an emitting LED affected the sensing LEDs within the distance of 3p by comparing V<sub>LED</sub>3. V<sub>LED</sub>3 were measured when the material on the cover glass was air and water with white pigments (water/W). <inline-formula> <tex-math notation="LaTeX">$\Delta \mathrm {V} _{\mathrm {LED}}\text{s}$ </tex-math></inline-formula> were 0.29 V and 1.13 V for glass-air and glass-water/W cases, respectively. It is found that the lights incident on the sensing LED comprised not only reflected lights by Fresnel reflection at the glass interface but also scattered lights in the water/W. A <inline-formula> <tex-math notation="LaTeX">$75\times $ </tex-math></inline-formula> magnified fake fingerprint was fabricated. Its material was poly-lactic acid with refractive index of 1.465 which is very close to that of a fingertip. Measured <inline-formula> <tex-math notation="LaTeX">$\Delta \mathrm {V}_{\mathrm {LED}}\text{s}$ </tex-math></inline-formula> at ridges and valleys were 0.48 V and 0.22 V, respectively. The ratio of 0.48/0.22 was 2.18 that is very close to 1.91 that is the ratio of light intensity at the ridge to that at the valley obtained by the calculation. This verifies that the proposed micro-LED display distinguishes the ridges and valleys of fingerprint without any help from any additional devices.https://ieeexplore.ieee.org/document/9828388/Fingerprint recognitionlight emitting diodeAMLED displaymicro-LED displayFresnel reflectionback-scattered reflection |
| spellingShingle | Dong-Hwan Jeon Won-Been Jeong Hoon-Ju Chung Seung-Woo Lee Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors IEEE Access Fingerprint recognition light emitting diode AMLED display micro-LED display Fresnel reflection back-scattered reflection |
| title | Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors |
| title_full | Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors |
| title_fullStr | Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors |
| title_full_unstemmed | Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors |
| title_short | Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors |
| title_sort | novel micro led display featuring fingerprint recognition without additional sensors |
| topic | Fingerprint recognition light emitting diode AMLED display micro-LED display Fresnel reflection back-scattered reflection |
| url | https://ieeexplore.ieee.org/document/9828388/ |
| work_keys_str_mv | AT donghwanjeon novelmicroleddisplayfeaturingfingerprintrecognitionwithoutadditionalsensors AT wonbeenjeong novelmicroleddisplayfeaturingfingerprintrecognitionwithoutadditionalsensors AT hoonjuchung novelmicroleddisplayfeaturingfingerprintrecognitionwithoutadditionalsensors AT seungwoolee novelmicroleddisplayfeaturingfingerprintrecognitionwithoutadditionalsensors |