Patents by Inventor Donald D. Boswell

Donald D. Boswell 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: 4127322
    Abstract: There is disclosed an electro-optical system for real time projection of very high brightness, full color pictorial images from television or other program sources onto a large display screen from a set of three reflection type AC driven field effect mode birefringent liquid crystal light valves each of which modulates a primary color component video image onto a collimated beam of polarized light of a given primary color by modulating the polarization state thereof. In order to achieve very high brightness without overheating the system it is necessary that none of the optical elements forming the projection beam optical system absorb light in carrying out their function. Hence all projection beam optical processes are non-absorptive to first order. The light valves are devices that receive and reflect projection light from an independent high power light source while modulating onto the reflected light video images derived from a low level light source such as a cathode ray tube.
    Type: Grant
    Filed: December 5, 1975
    Date of Patent: November 28, 1978
    Assignee: Hughes Aircraft Company
    Inventors: Alexander D. Jacobson, Jan Grinberg, Donald E. Sprotbery, Donald D. Boswell
  • Patent number: 4106853
    Abstract: A method and apparatus for increasing the contrast ratio of the output image from a cholestericnematic (storage mode) light valve. The increase in contrast ratio is achieved by applying a low amplitude voltage across the cell at an erasing frequency thereby causing increased scattering of light in the stored image areas and decreased scattering in the clear area.
    Type: Grant
    Filed: July 28, 1976
    Date of Patent: August 15, 1978
    Assignee: Hughes Aircraft Company
    Inventor: Donald D. Boswell
  • Patent number: 4048628
    Abstract: Methods and apparatus for erasing the stored scattering image in storage-type liquid crystal light valves. Erasure is accomplished by applying a signal from an erasing signal source across the liquid crystal cell where the signal is a voltage which is swept over the audio frequency range of 1 KHZ through 20 KHZ. In another embodiment, the erasing signal source supplies a precursor signal which has an initial frequency below the frequency threshold for scattering. This low frequency signal is maintained for a brief period of time to excite the entire liquid crystal cell into a uniform scattering state. The erasing signal is then swept over the audio frequency spectrum of 1 KHZ through 20 KHZ to cause the cell to return to the non-scattered, translucent state.
    Type: Grant
    Filed: July 28, 1976
    Date of Patent: September 13, 1977
    Assignee: Hughes Aircraft Company
    Inventor: Donald D. Boswell
  • Patent number: 4019807
    Abstract: There is disclosed a high performance reflective mode liquid crystal light valve suitable for general image processing and projection and particularly suited for application to real-time coherent optical data processing. A preferred example of the device uses a CdS photoconductor, a CdTe light absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The non-coherent light image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the AC voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state (voltage off the liquid crystal) and the optical birefringence effect to create the bright on-state.
    Type: Grant
    Filed: March 8, 1976
    Date of Patent: April 26, 1977
    Assignee: Hughes Aircraft Company
    Inventors: Donald D. Boswell, Jan Grinberg, Alexander D. Jacobson, Gary D. Myer
  • Patent number: 4018509
    Abstract: There is disclosed a high performance coherent optical data processing system using a reflective mode liquid crystal light valve which is particularly suited for application to real-time coherent optical data processing. A preferred example of the system uses a reflective light valve comprising a CdS photoconductor, a CdTe light absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The non-coherent light image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the AC voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state (voltage off the liquid crystal) and the optical birefringence effect to create the bright on-state.
    Type: Grant
    Filed: March 8, 1976
    Date of Patent: April 19, 1977
    Assignee: Hughes Aircraft Company
    Inventors: Donald D. Boswell, Jan Grinberg, Alexander D. Jacobson, Gary D. Myer