Abstract: An adaptive filter is provided featuring a speech spectrum estimator receiving as input an estimated spectral magnitude signal for a time frame of the input signal and generating an estimated speech spectral magnitude signal representing estimated spectral magnitude values for speech in a time frame. A spectral gain generator receives as input the estimated spectral magnitude signal and the estimated speech spectral magnitude signal and generates as output an initial spectral gain signal that yields an estimate of speech spectrum in a time frame of the input signal when the initial spectral gain signal is applied to the spectral signal. A spectral gain modifier receives as input the initial spectral gain signal and generates a modified gain signal by limiting a rate of change of the initial spectral gain signal with respect to the spectral gain over a number of previous time frames. The modified gain signal is then applied to the spectral signal, which is then converted to its time domain equivalent.

Abstract: A polarization converter polarizes an incident light beam having a first component with a first plane of polarization and a second component with a second plane of polarization orthogonal to the first plane. The polarization converter comprises a planar matrix for concentrating and collimating the incident light beam; a polarizer parallel to the planar matrix for refracting the first component and reflecting the second component; quarter-wave retarding means, parallel to the planar matrix and disposed between the planar matrix and the polarizer, for delaying the second component one-quarter wavelength relative to that of the first component; and reflection means, between the quarter-wave retarding means and the planar matrix, for reflecting the second component back through the quarter-wave retarder. The planar matrix may include on a top surface an array of first lenses and on a bottom surface an array of second lenses.

Abstract: A system and method for measuring the angular position of a rotatably positionable object are disclosed. The system includes a rotating polarizing filter coupled to the rotatably positionable object so that the rotating polarizing filter co-rotates with the rotatably positionable object. Light generated by a light source is directed along a path through the rotating polarizing filter and through a stationary polarizing filter. In this configuration, the intensity of the light passed through the rotating and stationary polarizing filters varies according to the angular position of the rotatably positionable object. A light sensor senses the intensity of the light passed through the rotating and stationary polarizing filters. Based on the intensity of the light, as sensed by the light sensor, a processor determines the angular position of the rotatably positionable object.In one embodiment, first and second stationary polarizing filters are provided having angularly offset orientations.

Abstract: The projector of the present invention provides a means for interactively displaying and annotating a document image at two separate locations. The projector consists of an image plate having an array of picture elements for displaying the image; a projection mechanism for projecting the image displayed by the image plate onto a projection screen; and a digitizer having a coordinate input array which corresponds to the array of picture elements of the image plate, wherein the image displayed by the image plate changes in response to coordinate inputs to the digitizer. A method for interactively annotating an image communicated between a remote and local image includes the procedure of simultaneously transmitting to the remote projector, annotations made to an image in the local projector.

Abstract: A videoconferencing unit is provided which integrates several components of a videoconferencing system to facilitate system setup and operation. The videoconferencing unit comprises a generally planar base structure adapted to be removably supported on a top surface of a video display monitor, such as a television monitor. The base structure terminates forwardly in a lip member which engages a front surface of the video display monitor. A first set of microphones is located at the lower portions of the lip member, and a second set of microphones is located at the upper edge surface of a tower member extending upwardly from the rear portion of the base structure. The vertical offset between the two sets of microphones thus established enables differential signal analysis to locate sound sources. The lip member may also be provided with one or more transmitters for transmitting control signals to a cooperatively placed receiver on the video display monitor.

Abstract: A condenser or aspheric lens comprising a condenser body having an aspheric section with a dome-shaped surface terminating in a circumferential perimeter and a sloping condenser surface extending from the circumferential perimeter outwardly and away from the aspheric section. A mirror assembly having a housing, an outer mirror assembly supported by the housing, and an inner mirror engaged to the outer mirror assembly. A method for capturing peripheral light rays from a light source. After a light member is illuminated to produce light rays, a portion of the light rays pass directly through the aspheric section of the condenser and a portion of the light rays are reflected off of an inner concave mirror surface for passage through the aspheric section of the condenser. A remaining portion of the light rays are reflected off of an outer peripheral mirror for passage through the condenser, preferably through a sloping condenser surface of the condenser.

Abstract: A circuit and method for energizing a discharge device, such as a flashlamp. A discharge device is electrically coupled to a pair of capacitors which are both charged to a desired potential level. One of the capacitors discharges through the discharge device to initially energize the discharge device until its potential level falls below the potential level of the other capacitor whereupon the other capacitor commences to discharge through the discharge device to sustain the energization of the discharge device.

Abstract: A polarization converter for polarizing a light beam by converting all light waves to the same orientation comprises 1) a first beam dividing matrix of refractory material for dividing a single, large light beam into smaller sub-beam 2) a second beam focusing matrix for polarizing select portions of the sub-beams, and 3) a series of narrow and shallow polarizing cells. The second beam focusing matrix further comprises a plurality of concave lenses for redirecting each sub-beam and quarter wave retarders disposed in alignment with, and adjacent to, the reflective side of an equal plurality of mirror segments. The polarizing cells include either a first beamsplitter or a second beamsplitter, where the first beamsplitters and second beamsplitters are disposed in opposing diagonal fashion and in an alternating manner.

Abstract: The projector of the present invention provides a means for interactively displaying and annotating a document image at two separate locations. The projector consists of an image plate having an array of picture elements for displaying the image; a projection mechanism for projecting the image displayed by the image plate onto a projection screen; and a digitizer having a coordinate input array which corresponds to the array of picture elements of the image plate, wherein the image displayed by the image plate changes in response to coordinate inputs to the digitizer. A method for interactively annotating an image communicated between a remote and local image includes the procedure of simultaneously transmitting to the remote projector, annotations made to an image in the local projector.