Patents by Inventor David W. Evans

David W. Evans 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: 5078486
    Abstract: A vision test apparatus illuminated by internal light source generating a constant, predetermined light intensity in the vicinity of the eye chart. The unit employs at least one photocell to monitor the light intensity near the eye chart and thereby adjust the amount of light generated by the light source to provide a constant level of illumination near the eye chart.
    Type: Grant
    Filed: October 13, 1989
    Date of Patent: January 7, 1992
    Inventor: David W. Evans
  • Patent number: 4927133
    Abstract: An angled conveyor for document packages comprises a transition conveyor belt, having an angled direction of motion relative to the direction of feed of document packages to the transition conveyor belt, and an output conveyor belt in line with and having a direction of motion that is substantially the same as the motion of the transition conveyor belt. Conveyor belts are of the endless type having their upper surfaces disposed substantially in the same horizontal plane. The transition conveyor belt is disposed laterally adjacently to the downstream end of a feed conveyor. A post extends from the apparatus frame structure vertically upward through a gap between the upstream end of the output conveyor belt and the downstream end of the transition conveyor belt in a transversally adjustable position. The post protrudes above the upper horizontal belt surfaces by a distance that is at least equal to the thickness of document packages conveyed.
    Type: Grant
    Filed: September 23, 1988
    Date of Patent: May 22, 1990
    Assignee: Bell & Howell Company
    Inventor: David W. Evans
  • Patent number: 4800404
    Abstract: Glare testing apparatus enclosed in a housing includes multiple discrete light sources for creating a glare condition in the field of view from an individual being tested to a target, and provision is made for selecting the location or locations of active glare sources, which includes a centrally located source of headlight glare, and a plurality of peripheral sources which can be energized selectively or collectively. Provision is also made for adjusting target luminance, glare intensity and the apparent distance between the target and the eye position in order to test near and far visual acuity under varied conditions of luminance and glare.
    Type: Grant
    Filed: September 22, 1986
    Date of Patent: January 24, 1989
    Assignee: Vistech Consultants, Inc.
    Inventors: Arthur P. Ginsburg, David W. Evans, Kenneth Blauvelt
  • Patent number: 4453804
    Abstract: In a system of real-time coherent optical filtering of visual imagery which encompasses a laser and a set of lenses for transmitting a visual target image of an input, a Fabry-Perot interferometer for filtering the target image to produce a filtered target image at an output having a predetermined bandwidth of spatial frequency information, the improvements relate to transmitting and original unfiltered image to the output for overlaying the filtered image for spatial enhancement of the predetermined spatial frequency bandwidth of information in the filtered image, and flickering the filtered image to achieve temporal enhancement of the visual information in the spatial frequency bandwidth of interest.
    Type: Grant
    Filed: January 6, 1982
    Date of Patent: June 12, 1984
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventor: David W. Evans
  • Patent number: 4448486
    Abstract: In a system of real-time coherent optical filtering of visual imagery having a Fabry-Perot interferometer for use as a variable bandpass spatial filter, the improvement of having the pair of mirrors of the interferometer mounted in spaced parallel relationship to one another for rotation about a common axis. The mirrors each have a reflectivity value which changes as a function of rotation. Thus, the bandwidth of the interferometer in acting as a filter can be adjusted by merely rotating one or both of the mirrors.
    Type: Grant
    Filed: January 6, 1982
    Date of Patent: May 15, 1984
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventor: David W. Evans
  • Patent number: 4426663
    Abstract: In a system for real-time coherent optical filtering of visual imagery which encompasses a laser and a set of lenses for transmitting a visual target image of an input, a Fabry-Perot interferometer for filtering the target image to produce a filtered target image at an output having a predetermined bandwidth of spatial frequency information, the improvements relate to the output being in the form of a low-light level video system capable of detecting the filtered image even when at a low level of luminance, and a laser adjustable in operating power between low and high levels and in operating wavelength within a wide range for adjusting the bandwidths of the interferometer between narrow and broad ranges.
    Type: Grant
    Filed: January 6, 1982
    Date of Patent: January 17, 1984
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: David W. Evans, Arthur P. Ginsburg