Patents by Inventor Hoi-Sing Kwok

Hoi-Sing Kwok has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 12019345
    Abstract: One or more devices, systems, methods and/or apparatus to facilitate suppression of fringe field effect, such as for diffraction grating and/or display purposes. In one embodiment, a ferroelectric liquid crystal (FLC) element can comprise a pair of conductive substrates, a FLC layer having a helical pitch and positioned between the conductive substrates, one or more spacers fixedly positioned between the conductive substrates, and an alignment layer positioned between the FLC layer and one of the conductive substrates. The alignment layer can be disposed at least partially contiguous with the FLC layer. The FLC layer can comprise a chiral smectic C* liquid crystal layer having at least one of a helical pitch smaller than an average cell gap of the FLC layer, or an average helical pitch of the FLC layer being smaller than an average thickness of the FLC layer between the conductive substrates.
    Type: Grant
    Filed: September 10, 2021
    Date of Patent: June 25, 2024
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
    Inventors: Zhibo Sun, Zhengnan Yuan, Abhishek Kumar Srivastava, Hoi-Sing Kwok
  • Patent number: 11880114
    Abstract: Techniques for using ferroelectric liquid crystals Dammann grating (FLCDG) for light detection and ranging devices are disclosed. In LiDAR devices, accuracy, response time, and cost performance can be limited by some factors, such as laser pulse width, time resolution of a time-to-digital conversion chip, detector bandwidth, shot noise, and time error generated by electronic circuits. A FLCDG-based architecture can improve a LiDAR device, and provide for one-shot capturing due to the high switching speed at very low driving voltage provided by ferroelectric liquid crystals and the equal diffracting ability of Dammann grating.
    Type: Grant
    Filed: August 27, 2020
    Date of Patent: January 23, 2024
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
    Inventors: Zhengnan Yuan, Abhishek Kumar Srivastava, Zhibo Sun, Hoi Sing Kwok
  • Publication number: 20230295438
    Abstract: A dichroic bis-azo biphenyl dye of the following formula: The substituents R1, R2, R3, R4 are alkyl (CnH2n+1) or alkenyl (CnH2n?1) groups with n=1-18. At least one substituent among R1R2R3R4 is different from the other substituents. A benzidine-free method of making a dichroic bis-azo biphenyl dye is provided in which the biphenyl portion of the dye is formed from different first and second mono-azo dyes by a cross-coupling reaction, which may be a Suzuki reaction. A polarizer is formed from a photoaligned layer of the bis-azo biphenyl dye on a substrate and exhibits a dichroic ratio of at least 40. Chemical modification of the photoaligned bis-azo biphenyl dye layer creates a broad-band thin film polarizer with low light scattering and high thermal and photo tolerances.
    Type: Application
    Filed: March 15, 2022
    Publication date: September 21, 2023
    Inventors: Valerii Vladimirovich VASHCHENKO, Olena VASHCHENKO, Hoi Sing KWOK, Cuiling MENG, Yeuk Lung HO
  • Publication number: 20230250338
    Abstract: There is provided a ferroelectric liquid crystal (FLC) material for the deformed helix FLC (DHFLC) electro-optical mode devices and shows optimum electro-optical properties including high tilt angle (>38°), and short helix pitch (<120 nm), and spontaneous polarization (>100 nC/cm2) comprising at least two components, wherein at least one FLC component is a chiral compound of Formula (I): particularly: wherein W1 and W2 are chiral groups with polar substituent at chiral centre, A and B are independently N atom or CH groups providing that at least one of A or B is N atom. Other various groups are as defined herein.
    Type: Application
    Filed: February 7, 2023
    Publication date: August 10, 2023
    Inventors: Valerii Vladimirovich VASHCHENKO, Olena V. VASHCHENKO, Abhishek Kumar SRIVASTAVA, Zhibo SUN, Zhengnan YUAN, Hoi Sing KWOK
  • Publication number: 20230244102
    Abstract: One or more devices, systems, methods and/or apparatus to facilitate suppression of fringe field effect, such as for diffraction grating and/or display purposes. In one embodiment, a ferroelectric liquid crystal (FLC) element can comprise a pair of conductive substrates, a FLC layer having a helical pitch and positioned between the conductive substrates, one or more spacers fixedly positioned between the conductive substrates, and an alignment layer positioned between the FLC layer and one of the conductive substrates. The alignment layer can be disposed at least partially contiguous with the FLC layer. The FLC layer can comprise a chiral smectic C* liquid crystal layer having at least one of a helical pitch smaller than an average cell gap of the FLC layer, or an average helical pitch of the FLC layer being smaller than an average thickness of the FLC layer between the conductive substrates.
    Type: Application
    Filed: September 10, 2021
    Publication date: August 3, 2023
    Inventors: Zhibo Sun, Zhengnan Yuan, Abhishek Kumar Srivastava, Hoi-Sing Kwok
  • Patent number: 11294241
    Abstract: A composite photoalignment layer for aligning liquid crystal molecules includes: a monomeric material; a photoinitiator or a thermal initiator; and an azo dye material. A method for preparing a composite photoalignment layer for aligning liquid crystal molecules includes: mixing, in solution form, a monomeric material, a photoinitiator or a thermal initiator, and an azo dye material; coating the mixed solution onto a substrate to form a thin film; exposing the thin film to polarized light; and, with a thermal initiator, heating the thin film to polymerize the monomeric material and form a solid thin film.
    Type: Grant
    Filed: September 22, 2020
    Date of Patent: April 5, 2022
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
    Inventors: Man Chun Tseng, Abhishek Kumar Srivastava, Cuiling Meng, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok, Yue Shi, Yeuk Lung Jacob Ho, Chenxiang Zhao
  • Patent number: 11056613
    Abstract: A method for fabricating quantum rods includes: preparing a Cd-precursor; preparing a S-precursor and CdSe seeds; preparing a Zn-precursor; mixing the S-precursor and the CdSe seeds with the Cd-precursor in a reaction mixture; adding the Zn-precursor to the reaction mixture; stopping the reaction; and performing a purification process to obtain the quantum rods.
    Type: Grant
    Filed: April 10, 2019
    Date of Patent: July 6, 2021
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
    Inventors: Maksym F. Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava, Hoi Sing Kwok
  • Patent number: 11015120
    Abstract: A low birefringence ferroelectric liquid crystal (FLC) mixture composed of at least two components shows birefringence in the range 0.05 to 0.14, which is suitable for the modern display and photonic devices. The cell gap can be tuned from 1.5 ?m to 4 ?m to reduces the fabrication complexity and chromatic distortion by electro-optical modulation. The FLC mixtures can be employed in a wide temperature range. The characteristics of the said FLC mixture can be tuned by tuning the concentration of the constituents of the mixture. The helical pitch of the FLC mixtures can be varied from 100 nm to 10 ?m. A smectic tilt angle can be varied between 17° to 45° and the spontaneous polarization can be tuned over a wide range to meet requirements of different electro-optical modes, and the FLC mixture is applicable for a wide variety of electro-optical effects.
    Type: Grant
    Filed: January 30, 2018
    Date of Patent: May 25, 2021
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Valerii Vladimirovich Vashchenko, Evgenii Pavlovich Pozhidaev, Abhishek Kumar Srivastava, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Patent number: 10948774
    Abstract: A photoaligned quantum rod enhancement film (QREF) includes: a substrate (802, 805); a photoalignment layer deposited on the substrate (802, 805); and a polymer layer deposited on the photoalignment layer, the polymer layer comprises a plurality of quantum rods, the plurality of quantum rods are configured to emit one or more wavelengths of light in response to pumping light, and are aligned to an alignment axis based on the photoalignment layer.
    Type: Grant
    Filed: May 10, 2017
    Date of Patent: March 16, 2021
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
    Inventors: Abhishek Kumar Srivastava, Wanlong Zhang, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Publication number: 20210063841
    Abstract: Techniques for using ferroelectric liquid crystals Dammann grating (FLCDG) for light detection and ranging devices are disclosed. In LiDAR devices, accuracy, response time, and cost performance can be limited by some factors, such as laser pulse width, time resolution of a time-to-digital conversion chip, detector bandwidth, shot noise, and time error generated by electronic circuits. A FLCDG-based architecture can improve a LiDAR device, and provide for one-shot capturing due to the high switching speed at very low driving voltage provided by ferroelectric liquid crystals and the equal diffracting ability of Dammann grating.
    Type: Application
    Filed: August 27, 2020
    Publication date: March 4, 2021
    Inventors: Zhengnan Yuan, Abhishek Kumar Srivastava, Zhibo Sun, Hoi Sing Kwok
  • Publication number: 20210011343
    Abstract: A composite photoalignment layer for aligning liquid crystal molecules includes: a monomeric material; a photoinitiator or a thermal initiator; and an azo dye material. A method for preparing a composite photoalignment layer for aligning liquid crystal molecules includes: mixing, in solution form, a monomeric material, a photoinitiator or a thermal initiator, and an azo dye material; coating the mixed solution onto a substrate to form a thin film; exposing the thin film to polarized light; and, with a thermal initiator, heating the thin film to polymerize the monomeric material and form a solid thin film.
    Type: Application
    Filed: September 22, 2020
    Publication date: January 14, 2021
    Inventors: Man Chun TSENG, Abhishek Kumar SRIVASTAVA, Cuiling MENG, Vladimir Grigorievich CHIGRINOV, Hoi Sing KWOK, Yue SHI, Yeuk Lung Jacob HO, Chenxiang ZHAO
  • Patent number: 10816855
    Abstract: A composite photoalignment layer for aligning liquid crystal molecules includes: a monomeric material; a photoinitiator or a thermal initiator; and an azo dye material. A method for preparing a composite photoalignment layer for aligning liquid crystal molecules includes: mixing, in solution form, a monomeric material, a photoinitiator or a thermal initiator, and an azo dye material; coating the mixed solution onto a substrate to form a thin film; exposing the thin film to polarized light; and, with a thermal initiator, heating the thin film to polymerize the monomeric material and form a solid thin film.
    Type: Grant
    Filed: October 17, 2017
    Date of Patent: October 27, 2020
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Man Chun Tseng, Abhishek Kumar Srivastava, Cuiling Meng, Hoi Sing Kwok, Yeuk Lung Jacob Ho
  • Publication number: 20200225542
    Abstract: Devices and methods relating to a vertical alignment layer with a preferred azimuthal angle for a liquid crystal device are provided. A method of preparation comprises preparing an alignment layer mixture of a polymeric vertical alignment material, an azo compound photo-aligned material, a reactive mesogen or liquid crystal monomer, a polyamic acid, a photo- or thermal-initiator, and an organic solvent, coating the alignment layer mixture onto a substrate, and irradiating the coated substrate with UV or blue light at an oblique angle.
    Type: Application
    Filed: March 26, 2020
    Publication date: July 16, 2020
    Inventors: Chenxiang ZHAO, Man Chun TSENG, Cuiling MENG, Shu Tuen TANG, Hoi Sing KWOK
  • Patent number: 10712618
    Abstract: Devices and method of fabrication a liquid crystal electro-optic device which is based on light scattering and diffraction from a multiple domain field-effect liquid crystal configuration are provided. The multiple domains include random liquid crystal alignment directions fabricated by photo-alignment and have sizes ranging from sub-micrometer to several micrometers. The random alignment in the plane can be of two or more directions whereas the pretilt angle can vary between zero and 90°. The randomness of the planar directions of the liquid crystal director can be generated by a designed photo mask in combination with uniaxial photo-alignment.
    Type: Grant
    Filed: March 1, 2018
    Date of Patent: July 14, 2020
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Hoi Sing Kwok, Martin Schadt, Fan Fan
  • Patent number: 10607556
    Abstract: Systems and methods for driving a pixel of a liquid crystal pixel array with a driving circuit are provided. An exemplary method includes: providing a data signal (Dm) to a storage element via the first transistor (T1); and providing a ramping voltage signal (VRAMP) to a gate of a second transistor (T2) of the driving circuit to control the on-off status of the second transistor (T2); wherein the ramping voltage signal (VRAMP) is based on data stored at the storage element; and wherein a duration of an on-state of the second transistor (T2) corresponds to a transmitting state for the pixel.
    Type: Grant
    Filed: November 6, 2015
    Date of Patent: March 31, 2020
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
    Inventors: Hoi Sing Kwok, Tsz Kin Ho, Vladimir G. Chigrinov
  • Patent number: 10504939
    Abstract: This disclosure relates generally to the three-dimensional (3D) integrated thin-film transistors (TFTs) with silicon and metal-oxide (MO) semiconductors as the active layers. In one or more embodiments, an apparatus is provided that comprises a first transistor comprising a silicon active layer, and a second transistor comprising a metal oxide active layer. The second transistor is vertically stacked on the first transistor, and the first transistor and the second transistor share a gate electrode formed between the silicon active layer and the metal oxide active layer. With these embodiments, the gate electrode corresponds to a top gate of the first transistor and a bottom gate of the second transistor.
    Type: Grant
    Filed: February 20, 2018
    Date of Patent: December 10, 2019
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Lei Lu, Wei Zhou, Man Wong, Hoi Sing Kwok
  • Patent number: 10451948
    Abstract: A standing helix ferroelectric liquid crystal display cell includes: two transparent substrates (102A, 102B); a ferroelectric liquid crystal layer (104) comprising ferroelectric liquid crystals in a standing helix configuration, the ferroelectric liquid crystal layer (104) being disposed between the two transparent substrates (102A, 102B), the ferroelectric liquid crystals having a helix axis perpendicular to the two substrates (102A, 102B) and chiral smectic liquid crystal helix pitch shorter than a wavelength of a polarized light normally impinging at least one of the two transparent substrates (102A, 102B); and inter-digital electrodes (105), disposed in plane with the two transparent substrates (102A, 102B), configured to apply an electric field to the ferroelectric liquid crystal layer (104) that provides a driving voltage below a critical voltage for helix unwinding.
    Type: Grant
    Filed: January 20, 2016
    Date of Patent: October 22, 2019
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
    Inventors: Evgenii P. Pozhidaev, Alexei D. Kiselev, Abhishek K. Srivastava, Vladimir G. Chigrinov, Hoi Sing Kwok
  • Publication number: 20190312175
    Abstract: A method for fabricating quantum rods includes: preparing a Cd-precursor; preparing a S-precursor and CdSe seeds; preparing a Zn-precursor; mixing the S-precursor and the CdSe seeds with the Cd-precursor in a reaction mixture; adding the Zn-precursor to the reaction mixture; stopping the reaction; and performing a purification process to obtain the quantum rods.
    Type: Application
    Filed: April 10, 2019
    Publication date: October 10, 2019
    Applicant: The Hong Kong University of Science and Technology
    Inventors: Maksym F. Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava, Hoi Sing Kwok
  • Patent number: 10381564
    Abstract: A method of fabricating a hybrid organic-inorganic halide perovskite film includes depositing a precursor layer onto a substrate, the precursor layer comprising metal halide, placing an organic source-material layer onto a boat, the organic source-material layer comprising an organic cation, and annealing the precursor layer and the organic source-material layer in a vacuum chamber enclosed in a constrained volume.
    Type: Grant
    Filed: August 17, 2016
    Date of Patent: August 13, 2019
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Hoi Sing Kwok, Guijun Li, Yeuk Lung Jacob Ho, Man Wong
  • Patent number: 10281731
    Abstract: A 2D/3D switchable liquid crystal lens device includes: a polarization-dependent lens array, configured to provide a focusing effect for impinging light having a first plane of polarization of the impinging light and to provide no focusing effect for impinging light have a second plane of polarization orthogonal to the first plane of polarization; a switchable polarization rotating stage, comprising bi-stable liquid crystals, wherein the switchable polarization rotating stage is configured to output light having the first plane of polarization to the polarization-dependent lens array while the bi-stable liquid crystals are in a first state, and to output light having the second plane of polarization to the polarization-dependent lens array while the bi-stable liquid crystals are in a second state; and a driving system, configured to switch the bi-stable liquid crystals of the switchable polarization rotating stage between the first state and the second state.
    Type: Grant
    Filed: May 15, 2015
    Date of Patent: May 7, 2019
    Assignee: THE HONG KONG UNIVERSITY OF SCIENCE & TECHNOLOGY
    Inventors: Abhishek Kumar Srivastava, Vladimir Grigorievich Chigrinov, Hoi-Sing Kwok