Abstract: An optical encoder for producing an electrical signal representative of the angular position and velocity of a rotatable shaft. A flexible code disk, which is coupled to the shaft via a hub portion, has a plurality of slots located adjacent its outer rim, for alternately blocking and permitting transmission of a light beam to each of a plurality of separate photocells, as the disk is rotated. The rim of the disc is disposed in a special low-friction seat, whereby the slots are maintained in proper alignment with the photocells, even though the shaft may have a slight angular misalignment relative to the encoder. The photocells are formed on a common silicon substrate that has a single diffusion layer, and the electrical outputs of separate photocells are connected in a push-pull circuit arrangement.

Abstract: An optical encoder for producing an electrical signal representative of the angular position and velocity of a rotatable shaft. A flexible code disk, which is coupled to the shaft via a hub portion, has a plurality of slots located adjacent its outer rim, for alternately blocking and permitting transmission of a light beam to each of a plurality of separate photocells, as the disk is rotated. The rim of the disc is disposed in a special low-friction seat, whereby the slots are maintained in proper alignment with the photocells, even though the shaft may have a slight angular misalignment relative to the encoder. The photocells are formed on a common silicon substrate that has a single diffusion layer, and the electrical outputs of separate photocells are connected in a push-pull circuit arrangement.

Abstract: A nonlinear load circuit, consisting of a transistor and a resistor in series, is provided for the photovoltaic array under test. Base bias for the transistor is supplied via the source-to-drain path of a field effect transistor (FET). A ramp signal is fed to the gate of the FET. As a result of the nonlinear relationship between the gate voltage and source-to-drain current of the FET, equal ramp steps result in a nonlinear effective load for the array under test. This produces a very gradual change in load impedance for each ramp step in the regions of high current output from the array ("current mode"), and relatively greater changes in load impedance for each ramp step at output levels of lower current and higher voltage from the array ("voltage mode").Advantageously, the array is illuminated by a pulsed flash lamp. A photosensor detects the light level incident on the array, and comparison circuitry provides a "sample" pulse each time that the incident light level is at a selected value.

Abstract: This complementary photovoltaic cell has both an N+/P+ junction and a P+/N junction on the same epitaxial substrate, and so provides simultaneous photo-responsive outputs of both negative and positive polarity. A vertical photo-junction supplements the current output from the N+/P+ junction, and improves the efficiency of the cell. The N+/P+ junction by itself exhibits a high open circuit voltage.

Abstract: In this full duplex card reader/printer, a transport mechanism carries a card first past a read head at a constant rate and then incrementally past a printer. Under microprocessor control a message is printed on the card which is responsive to data read from the same card. A first transducer associated with the drive transport mechanism provides "read sprocket" pulses that are utilized by the microprocessor to ascertain the presence under the read head of a card data column. Stepping of the card past the printer is enabled by the microprocessor when a responsive message is ready for printing. As the card is stepped to each new print position, a "move sprocket" pulse is transmitted to the microprocessor. The microprocessor then compares the next message character with the character available for printing, as indicated by a set of pulses supplied from the printer. When these are the same, the microprocessor generates a command to print the character.

Abstract: High efficiency, low cost solar energy conversation is facilitated by using tubular photovoltaic solar cells situated at the focus of a line-generated paraboloidal reflector. Advantageously each solar cell comprises a pair of concentric glass tubes that are hermetically sealed at the ends. A photovoltaic junction is formed over the entire inside surface of one of the concentric tubes. For example, this may comprise an inner electrically conductive film, contiguous layers of Cu.sub.2 S and CdS forming a heterojunction, and an outer film of optically transparent but electrically conductive material. The conductive films provide electrical connection to the junction via external contacts that are symmetrically disposed at the ends of the tubular cell.In other embodiments the photovoltaic junction is formed in a crystalline silicon layer that is grown in situ on one of the glass tubes. Techniques for promoting oriented semiconductor crystalline growth are disclosed.

Abstract: The spectral response of a photovoltaic cell is controlled by modifying the minority carrier transport characteristics of the cell semiconductor body. Recombination centers are provided in the body that reduce the lifetime or diffusion distance of minority carriers. Thus a reduced percentage of minority carriers produced deep in the body by absorption of relatively long wavelength photons reach the cell junction, as compared with carriers produced at lesser depth by absorption of shorter wavelength photons. The result is a shift in the peak spectral response of the cell toward shorter wavelengths.

Abstract: Photo-Darlington devices having a response within a narrow range of current output for a certain illumination level are produced by initially providing each device with a light-admitting opening of smaller than requisite size. The device outputs are measured separately, and based on such measurements, the individual openings are enlarged sufficiently so that the output current from each device falls within the requisite range.For improved performance, each photo-Darlington device has a pair of emitters spaced on opposite sides of the light admitting opening. This provides better efficiency and results in more consistent output despite non-uniform illumination of the device.

Abstract: High efficiency, low cost solar energy conversion is facilitated by using tubular photovoltaic solar cells situated at the focus of a line-generated paraboloidal reflector. Advantageously, each solar cell comprises a pair of concentric glass tubes that are hermetically sealed at the ends. A photovoltaic junction is formed over the entire inside surface of one of the concentric tubes. For example, this may comprise an inner electrically conductive film, contiguous layers of Cu.sub.2 S and CdS forming a heterojunction, and an outer film of optically transparent but electrically conductive material. The conductive films provide electrical connection to the junction via external contacts that are symmetrically disposed at the ends of the tubular cell.In other embodiments the photovoltaic junction is formed in a crystalline silicon layer that is grown in situ on one of the glass tubes. Techniques for promoting oriented semiconductor crystalline growth are disclosed.

Abstract: A detector for tubular transparent articles employs a light beam directed across an opening in a housing, along a path offset from a diameter of that opening. When a tubular article is present in the opening, the light is glazingly deflected by a curved surface of the article, optimally at the critical angle of maximum light reflection. The resultant reduction in beam intensity is sensed by a photodetector to indicate the presence of the article.