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: 9575366
    Abstract: A liquid crystal cell structure is provided. The liquid crystal cell structure includes: two polarizers; and a liquid crystal diffractive light modulating cell placed between the two polarizers. The cell includes: two transparent substrates treated by photoalignment; and a ferroelectric liquid crystal layer disposed between the two transparent substrates with current conducting layers, the ferroelectric liquid crystal layer comprising ferroelectric liquid crystals. The two transparent substrates treated by photoalignment are configured to provide multiple alignment domains in the ferroelectric liquid crystals with a planar surface orientation. Adjacent domains of the multiple alignment domains are oriented at an angle with respect to each other.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: February 21, 2017
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Abhishek Kumar Srivastava, Wei Hu, Yanqing Lu, Fei Xu, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Publication number: 20160233338
    Abstract: Thin film transistors are provided that include a metal oxide active layer with source and drain regions having a reduced resistivity relative to the metal oxide based on doping of the source and drain regions at room temperature. In an aspect, a transistor structure is provided, that includes a substrate, and source and drain regions within a doped active layer having resulted from doping of an active layer comprising metal-oxide and formed on the substrate, wherein the doped active layer was doped at room temperature and without thermal annealing, thereby resulting in a reduction of a resistivity of the source and drain regions of the doped active layer relative to the active layer prior to the doping. In an aspect, the source and drain regions have a resistivity of about 10.0 m?·cm after being doped with stable ions and without subsequent activation of the ions via annealing.
    Type: Application
    Filed: February 9, 2015
    Publication date: August 11, 2016
    Inventors: LEI LU, MAN WONG, HOI SING KWOK
  • Patent number: 9383607
    Abstract: The present invention provides a patterned polarization converter having multiple domains that can be used to convert input linear polarized light to output light with spatially varying polarization states, including domains that produce linearly polarized light and domains that produce circular polarized light based on the patterning of the domains. A patterned polarization converter having multiple domains may be used in a polarization sensor application capable of detecting the polarization state of input light. The present invention further provides patterned radial and azimuthal polarization converters, which have utility in applications such as optical tweezers. Additionally, patterned polarization converters may be used to fabricate more patterned polarization converters having the same pattern using one-step photoalignment to copy the pattern of an existing patterned polarization converter to an unpatterned photoalignment layer.
    Type: Grant
    Filed: November 25, 2014
    Date of Patent: July 5, 2016
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Tao Du, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Publication number: 20160187730
    Abstract: A polymer film with aligned geometrically anisotropic nanostructures includes: an alignment layer; and a mixture of liquid crystal polymer and geometrically anisotropic nanostructures. Methods for aligning geometrically anisotropic nanostructures and for optically manipulating geometrically anisotropic nanostructures are also provided.
    Type: Application
    Filed: November 25, 2015
    Publication date: June 30, 2016
    Inventors: Tao Du, Abhishek Kumar Srivastava, Valerii Vladimirovich Vashchenko, Vladimir Grigorievich Chigrinov, Hoi-Sing Kwok
  • Publication number: 20160187691
    Abstract: An electrically suppressed helix (ESH) ferroelectric liquid crystal (FLC) display cell with fast response includes: a liquid crystal layer, disposed between two transparent substrates, wherein helix pitch of chiral smectic liquid crystals of the liquid crystal layer is less than the thickness of the liquid crystal layer; at least one polarizer; and a voltage source, configured to apply electrical driving voltage pulses to electrodes of the display cell with amplitude greater than a critical voltage for helix unwinding of the chiral smectic liquid crystals.
    Type: Application
    Filed: March 10, 2016
    Publication date: June 30, 2016
    Inventors: Abhishek Kumar Srivastava, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Patent number: 9366934
    Abstract: A field sequential color (FSC) ferroelectric liquid crystal (FLC) display cell, part of an FSC display, is provided. The FSC FLC display cell includes: two polarizers; an FLC layer, positioned between the two polarizers, the FLC layer comprising FLCs with helix pitch less than the thickness of the FLC layer; and a voltage source, configured to apply an electrical driving voltage to the FLC layer, the electrical driving voltage applied to the FLC layer having an amplitude greater than a threshold voltage for helix unwinding, and wherein the voltage source is further configured to apply electrical driving voltages to light emitting diodes (LEDs) of the FSC display to illuminate pixels of the FSC display. The pixels are illuminated in an FSC manner. The FLC layer is configured to provide a defect-free layer of FLC under the electrical driving voltage applied to the FLC layer.
    Type: Grant
    Filed: November 1, 2013
    Date of Patent: June 14, 2016
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Abhishek Kumar Srivastava, Ying Ma, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Patent number: 9341855
    Abstract: A polarization converter and polarization conversion systems are provided. The polarization converter and polarization conversion systems include a patterned polarization grating with left hand and right hand polarization grating domains. The polarization grating domains are configured to diffract incident non-polarized light into beams having left and right circular polarization states.
    Type: Grant
    Filed: May 6, 2013
    Date of Patent: May 17, 2016
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Tao Du, Fan Fan, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Patent number: 9340634
    Abstract: The present invention relates to materials used for aligning liquid crystals of liquid crystal display elements and to a polymer for use in liquid crystal vertical alignment layer used in producing a liquid crystal vertical alignment layer. The polymer for use in a liquid crystal vertical alignment layer includes (a) a moiety that is photochemically isomerizable but not photochemically crosslinked, (b) a moiety that is photochemically crosslinkable, and (c) a moiety that stabilizes a vertical alignment. The polymer can be used to produce a vertical alignment layer that has a liquid crystal alignment property enabling control of alignment at a low UV dose and that offers a large pretilt angle and superior optical stability.
    Type: Grant
    Filed: March 29, 2011
    Date of Patent: May 17, 2016
    Assignee: DIC CORPORATION
    Inventors: Sayaka Nose, Yutaka Nagashima, Isa Nishiyama, Haruyoshi Takatsu, Martin Schadt, Vladimir Chigrinov, Hoi Sing Kwok
  • Patent number: 9299863
    Abstract: A solar cell photovoltaic device using ultrathin films of polycrystalline silicon and deep uneven surface structures is disclosed. According to one embodiment, the uneven structures include one or more pits having a depth of at least 10 microns. According to another embodiment, the uneven structures include one or more cones or columns having a height or at least 10 microns. Because the unevenness of the structures, the photovoltaic device is able to use a very thin layer of polycrystalline silicon to effectively trap and absorb light.
    Type: Grant
    Filed: May 7, 2009
    Date of Patent: March 29, 2016
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Hoi Sing Kwok, Zhiguo Meng, Man Wong
  • Publication number: 20160020095
    Abstract: Techniques are provided for forming thin film transistors having a polycrystalline silicon active layer formed by metal-induced crystallization (MIC) of amorphous silicon in an oxidizing atmosphere. In an aspect, a transistor device, is provided that includes a source region and a drain region formed on a substrate, and an active channel region formed on the substrate and electrically connecting the source region and the drain region. The active channel region is formed with a polycrystalline silicon layer having resulted from annealing an amorphous silicon layer formed on the substrate and having a metal layer formed thereon, wherein the annealing of the amorphous silicon layer was at least partially performed in an oxidizing ambience, thereby resulting in crystallization of the amorphous silicon layer to form the polycrystalline silicon layer.
    Type: Application
    Filed: June 22, 2015
    Publication date: January 21, 2016
    Inventors: Hoi Sing Kwok, Man Wong, Rongsheng Chen, Meng Zhang, Wei Zhou
  • Patent number: 9214568
    Abstract: A thin film transistor includes: a source region; a drain region; and a polycrystalline thin film active channel region connected to the source region and the drain region, the active channel region comprising grains and being doped with a two-dimensional pattern comprising a plurality of doped regions, the plurality of doped regions each comprising at least portions of a plurality of the grains and at least one grain boundary.
    Type: Grant
    Filed: December 12, 2013
    Date of Patent: December 15, 2015
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Hoi Sing Kwok, Meng Zhang, Shuming Chen, Wei Zhou, Man Wong
  • Publication number: 20150331247
    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: Application
    Filed: May 15, 2015
    Publication date: November 19, 2015
    Inventors: Abhishek Kumar Srivastava, Vladimir Grigorievich Chigrinov, Hoi-Sing Kwok
  • Patent number: 9166197
    Abstract: The invention provides an organic light emitting diode (OLED), having a substrate, an anode layer of silver or gold, wherein the anode layer is treated with CF4 plasma to enhance the hole injection of the semitransparent anode layer.
    Type: Grant
    Filed: June 29, 2006
    Date of Patent: October 20, 2015
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Hoi Sing Kwok, Man Wong, Huajun Peng, Jiaxin Sun
  • Publication number: 20150280002
    Abstract: An apparatus is provided that includes a substrate and source and drain regions within an annealed active layer having resulted from an annealing of an active layer comprising metal-oxide and formed on the substrate, and an impermeable layer over the source and drain regions of the annealed active layer, wherein the annealing resulting in the annealed active layer was performed with the impermeable layer over portions of the active layer corresponding to the source and drain regions, thereby resulting in a reduction of a resistivity of the source and drain regions of the annealed active layer relative to the active layer. In another aspect, a junctionless transistor is provided wherein the entire active area has a low resistivity based on annealing of an active layer including metal oxide while uncovered or at least partially covered with layers of various gas permeability under oxidizing or non-oxidizing conditions.
    Type: Application
    Filed: March 27, 2015
    Publication date: October 1, 2015
    Inventors: LEI LU, MAN WONG, HOI SING KWOK
  • Publication number: 20150264327
    Abstract: A projection device including a light source, a reflective spatial polarization modulator, a polarization grating, and a projection lens is provided. The light source is configured to provide a light beam. The reflective spatial polarization modulator is disposed on a path of the light beam and configured to reflect the light beam and modulate a polarization state of the light beam. The polarization grating is disposed on the path of the light beam between the light source and the reflective spatial polarization modulator, wherein the reflective spatial polarization modulator reflects the light beam from the reflective spatial polarization modulator back to the polarization grating. The projection lens is disposed on the path of the light beam from the reflective spatial polarization modulator, wherein the polarization grating is disposed on the path of the light beam between the reflective spatial polarization modulator and the projection lens.
    Type: Application
    Filed: March 12, 2014
    Publication date: September 17, 2015
    Applicants: Himax Display, Inc., The Hong Kong University of Science and Technology
    Inventors: Hoi-Sing Kwok, Li Tan, Yuet-Wing Li
  • Publication number: 20150247617
    Abstract: A liquid crystal display (LCD) backlight system includes: a light source, configured to generate light; a patterned polarization grating polarization converter (PPG-PC) assembly, configured to convert the generated light from a first polarization state to a second polarization state. The PPG-PC further includes: a patterned polarization grating (PPG) having a plurality of domains, wherein the plurality of domains of the PPG include at least two different types of domains, and wherein each domain of the PPG is configured to diffract incident light into first and second types of light beams corresponding to a first diffraction order; and a patterned retarder (PR), having a plurality of domains, the plurality of domains of the PR including domains corresponding to areas where the first type of light beams output from the PPG and including domains corresponding to areas where the second type of light beams output from the PPG converge.
    Type: Application
    Filed: April 17, 2015
    Publication date: September 3, 2015
    Inventors: Tao DU, Fan FAN, Vladimir Grigorievich CHIGRINOV, Hoi Sing KWOK
  • Patent number: 9046729
    Abstract: A liquid crystal optical device that includes a first substrate layer that is substantially flat and a second substrate layer that is substantially flat and parallel to the first substrate layer. The liquid crystal optical device further includes a layer of cholesteric liquid crystal disposed between the first substrate layer and the second substrate layer, where the layer of cholesteric liquid crystal is arranged in domains, each domain having a helical axis, wherein the helical axes of the domains have a plurality of orientations relative to an orientation of the first and second substrate layers, and where a wavefront of a light wave having a wavelength within a range of wavelengths changes after reflecting from the layer of cholesteric liquid crystal.
    Type: Grant
    Filed: March 23, 2012
    Date of Patent: June 2, 2015
    Assignee: The Hong Kong University of Science and Technology
    Inventors: Sergiy I. Valyukh, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok, Iryna V. Valyukh
  • Publication number: 20150138496
    Abstract: The present invention provides an electrically suppressed helix ferroelectric liquid crystal (ESHFLC) cell with polymer stabilization. The cell has a liquid crystal (LC) material that is a mixture comprising a monomer, a photo-initiator and a ferroelectric liquid crystal (FLC) where a polymer network has been established at a certain temperature to achieve constraints of ESHFLC electro-optical mode. The resultant mixture is characterized by a helix pitch less than and comparable to a FLC layer thickness of the cell, and provides a selective reflection in an UV region. The concentration of the monomer in the pure FLC mixture has also been optimized for the phase diagram, scattering and the tilt angle. The resultant mixture, i.e. the polymer stabilized ESHFLC cell, follows all constraints of the ESHFLC electro-optical mode and shows electro-optical characteristics similar to a typical ESHFLC cell.
    Type: Application
    Filed: November 12, 2014
    Publication date: May 21, 2015
    Inventors: Abhishek Kumar SRIVASTAVA, Ying MA, Qi GUO, Vladimir Grigorievich CHIGRINOV, Hoi Sing KWOK
  • Publication number: 20150079302
    Abstract: The present invention provides a patterned polarization converter having multiple domains that can be used to convert input linear polarized light to output light with spatially varying polarization states, including domains that produce linearly polarized light and domains that produce circular polarized light based on the patterning of the domains. A patterned polarization converter having multiple domains may be used in a polarization sensor application capable of detecting the polarization state of input light. The present invention further provides patterned radial and azimuthal polarization converters, which have utility in applications such as optical tweezers. Additionally, patterned polarization converters may be used to fabricate more patterned polarization converters having the same pattern using one-step photoalignment to copy the pattern of an existing patterned polarization converter to an unpatterned photoalignment layer.
    Type: Application
    Filed: November 25, 2014
    Publication date: March 19, 2015
    Inventors: Tao Du, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
  • Publication number: 20150036084
    Abstract: A liquid crystal Fresnel lens is provided. The liquid crystal Fresnel lens includes a liquid crystal cell and two polarizers. The liquid crystal cell includes: two transparent substrates having conducting layers disposed thereon with alignment layers, wherein an alignment pattern formed by the alignment layers are configured to provide multiple alignment domains in a Fresnel zones pattern, and wherein an easy axis of adjacent alignment domains are oriented at an angle relative to one another; and a ferroelectric liquid crystal layer disposed between the two transparent substrates, wherein the ferroelectric liquid crystal layer has a planar surface orientation and smectic layers perpendicular to the two transparent substrates. The liquid crystal cell is disposed between the two polarizers.
    Type: Application
    Filed: August 5, 2014
    Publication date: February 5, 2015
    Inventors: Abhishek Kumar Srivastava, Xiaoqian Wang, Vladimir Grigorievich Chigrinov, Hoi-Sing Kwok