Abstract: An apparatus is provided for determining the position of a shaft that is rotatably displaceable about a longitudinal axis. The apparatus includes a source of light energy, a light detecting device arranged adjacent the shaft. A rotatably displaceable disk having a triangular opening in the disk is mounted between the source of light energy and the light detecting device. A position-determining circuit connected to the light detecting device measures the magnitude of light that the light detecting device reads from the light emanating from the disk opening and applies the output to a position-determining scheme.

Abstract: A method is provided for determining the position of a shaft along a longitudinal axis. The method is used with a device that includes first, second, and third light detecting devices arranged about the shaft in a specific geometric pattern, with the second energy detecting device mounted to the shaft. A light directing device is arranged to deliver light energy sequentially between the first, the second, and the third light detecting devices. The method for determining the position of the shaft comprises the steps of generating a first measured value by measuring the interval the light energy directing device travels between the first and the second light detecting devices. A second measured value is generated that measures the interval the energy directing device travels between the second and the third energy detecting devices. A percentage of shaft rotation is calculated using the first and second measured values.

Abstract: An apparatus is provided for determining the position of a shaft that is rotatably displaceable about a longitudinal axis. The apparatus includes a magnet, first and second magnet-detecting devices that are arranged adjacent the shaft, and a third magnet-detecting device mounted on the shaft. A rotatably displaceable disk having the magnet mounted thereon is arranged to allow the magnetic field produced by the magnet to pass over and activate each of the magnet detection devices sequentially. A position-determining circuit connected to the magnet-detecting devices, measures the time interval that the magnet-detecting devices are sequentially activated by the magnetic field and applies the time so measured to a position-determining scheme. The position-determining scheme uses the time measured and the physical geometry of the apparatus to determine the position of the shaft.

Abstract: An apparatus is provided for determining the position of a shaft that is rotatably displaceable about a longitudinal axis. The apparatus includes a source of light energy, first and second light detecting devices that are arranged adjacent the shaft, and a third light detecting device mounted on the shaft. A rotatably displaceable disc having an opening near the disc's perimeter is mounted between the source of light energy and the light detecting devices. A position-determining circuit connected to the light detecting devices measures the time that the light detecting devices are sequentially activated by the light emanating from the disc opening and applies the time so measured to a position-determining scheme. The position-determining scheme uses the time measured and the physical geometry of the apparatus to determine the position of the shaft.