Abstract:
An enhanced delta modulation encoder (10) includes a spectrum tilter (24), a 1 bit analog-to-digital converter (26), a sampling circuit (28) and an internal decoder (22). An analog input signal and an internal analog signal from the internal decoder (22) are summed to provide an analog dither signal. The analog dither signal is tilted by the spectrum tilter (24) and is provided to the 1 bit analog-to-digital converter (26) which generates a digital signal. The sampling circuit (22) receives the digital signal from the analog-to-digital converter (26) and generates a digital output which is fed back to the internal decoder (22). The spectrum tilter (24) comprises at least three integrator circuits (38, 56, 58) and a clipping circuit (36). The three integrator circuits (38, 56, 58) tilt the frequency spectrum of noise above the maximum frequency of interest, the clipping circuit (36) prevents the encoder from becoming unstable.
Abstract:
Un interferometre permet de detecter optiquement des deplacements sur une surface. Les interferometres de l'art anterieur utilisent un passage d'air pour transmettre la lumiere depuis la source a l'eventuelle cible d'interferences. Des fluctuations de l'atmosphere ambiante dues aux variations locales de temperature ou de pression peuvent introduire des changements de phase dans les chemins optiques qui ne sont pas les memes tant pour le signal que pour le chemin de reference. Ces fluctuations, qui limitent la sensibilite fondamentale du dispositif, sont reduites au minimum en utilisant des fibres optiques pour diriger la lumiere dans l'interferometre. Un premier guide d'ondes a fibre optique (18) transporte la lumiere depuis un laser (12) vers une surface de detection (22). Un second guide d'ondes a fibre optique (20) transporte la lumiere depuis la source de lumiere (12) vers la surface a mesurer (24). Un troisieme guide d'ondes a fibre optique (30) capture une partie de la lumiere reflechie de la surface (24) et la transporte vers la surface de detection (22). Le detecteur detecte la configuration d'interferences resultant des projections lumineuses simultanees du premier et du troisieme guides d'ondes a fibre optique.
Abstract:
Starting control circuit for an alternating current motor having a run winding (22) and a start winding (24) and a mechanical rotational output (26). The motor is powered by an alternating current source (30). A reference oscillator (32) produces pulses having a reference frequency. A first control circuit (38, 40, 42) is provided for counting the number of reference pulses produced during a predetermined number of cycles of the alternating current source. A sensor (44) is provided for sensing a predetermined amount of rotational movement of the mechanical rotational output of the motor and producing a sensor pulse indicative thereof. A second control circuit (46, 48) is provided for counting the number of reference pulses produced during the time between a predetermined number of sensor pulses and for comparing the counts on the first and second control circuits. The second control circuit assumes first and second output states dependent on the relationship between the first and second output counts. A switch (54) is connected to the second control circuit, the alternating current source and the start winding for connecting and disconnecting the alternating current source and the start winding in response to the output state of the second control circuit.
Abstract:
A circuit for boosting a digital data signal which is transmitted on a transmission line (22), which comprises a negative impedance bistable device (20) for enhancing the amplitude and rise time of the digital data signal. A plurality of the booster circuits (20) may be coupled to the transmission line (22) at various points to boost the digital data signal. When a plurality of the booster circuits (20) are coupled to the transmission line (22) there is no serial reliability problem because the booster circuits (20) are weakly coupled to the transmission line (22).
Abstract:
An interferometer for optically sensing displacements in a surface. Prior art interferometers use an air path to transmit the light from the source to the eventual interference target. Fluctuations in the ambient atmosphere due to local variations in temperature or pressure can introduce phase changes into the optical paths which are not the same for both the signal and the reference path. These fluctuations, which limit the ultimate sensitivity of the device, are minimized by utilizing fiber optics to direct the light within the interferometer. A first fiber optic waveguide (56) receives light from a laser (12) in one end and transports it to the other end (60) where a portion is back reflected and a portion is projected upon the surface (24). The reflected light from the surface (24) re-enters the fiber optic at the end (60) and combines with the back reflected signal to form an optical information wave. This optical information wave is evanescently coupled over a length, L, to a second fiber optic waveguide (58) which transports this wave to a detector (44). An absorber (66) is placed at one end of fiber optic waveguide (58) in order to eliminate end reflections in fiber optic waveguide (58).
Abstract:
Dispositifs optiques ayant des fibres optiques supportees de maniere rigide et leur procede de fabrication, ou une ou plusieurs fibres optiques (20, 26, 68, 78) sont en interface avec un materiau de support rigide (24, 30, 72, 74) par restructuration moleculaire des zones de la surface d'interface des fibres et du materiau de support. La fibre optique supportee de maniere rigide peut etre fabriquee en assemblant une portion de la surface exterieure longitudinale de la fibre (20, 26, 68, 78) en juxtaposition avec un materiau de support rigide (24, 30, 72, 74) ayant un point de fusion inferieur a celui de la fibre. Cet assemblage peut etre chauffe pour permettre un ramollissement partiel du materiau de support (24, 30, 72, 74) le long de la surface exterieure de la fibre (20, 26, 68, 78) pour permettre la fusion des deux. L'assemblage peut alors etre refroidi en ramenant sa temperature en dessous du point de fusion du materiau de support (24, 30, 72, 74) pour obtenir un assemblage a fibre optique consolide comprenant une fibre optique ayant fusionne avec un materiau de support rigide. Divers dispositifs optiques peuvent etre formes a partir de combinaisons de ces fibres optiques supportees de maniere rigide.
Abstract:
Dispositifs optiques possedant une ou plusieurs fibres optiques supportees rigidement et procede de fabrication, dans lequel une ou plusieurs fibres optiques (20, 26, 68, 78) sont interfacees avec un materiau rigide de support (24, 30, 72, 74) au moyen d'une restructuration moleculaire des surfaces specifiques d'interface des fibres et du materiau de support. La fibre optique supportee rigidement peut etre obtenue par l'assemblage d'une partie de surface exterieure longitudinale de la fibre (20, 26, 68, 78) en juxtaposition avec un materiau de support rigide (24, 30, 72, 74) possedant un point de fusion inferieur a celui de la fibre. Cet assemblage peut etre chauffe pour permettre le ramollissement partiel du materiau de support (24, 30, 72, 74) le long de la surface exterieure de la fibre (20, 26, 68, 78) pour permettre la fusion des deux surfaces. L'assemblage peut ensuite etre refroidi en dessous du point de fusion du materiau de support 24, 30, 72, 74) pour produire un assemblage de fibres optiques de construction renforcee comprenant une fibre optique fondue sur un materiau rigide de support. Plusieurs dispositifs optiques peuvent etre formes en combinant ces fibres optiques supportees rigidement.
Abstract:
Microprocessor controlled micro-stepping chart drive circuit. The invention comprises a step clock system (10), a microprocessor controller (12) and a motor drive circuit (16). A speed selector (14) establishes a numerical constant within the controller. This numerical constant is decremented down with each pulse of the step clock (10). When the counter reaches zero, the motor drive circuit is update. Therefore, the time between updates of the motor drive circuit is a function of the value of the numerical constant.