Linear Technology Corporation

Other

Genentech, Inc.

James M Williams

James Robert Swartz

Robert E Wilson

Ronald T Kaneshiro

Brenton Arthur Baugh

James L Chang

Leonard H Sherman

Ban-Poh Loh

Pradeep Raj Komar

Various concepts and techniques are disclosed for measuring the voltage of a power source. An apparatus includes a voltage metering circuit and a transformer having a first winding coupled to the voltage metering circuit and a second winding for coupling to a power source.

Method and apparatus for measuring the voltage of a power source

Waveguide based connector systems for optically coupling a fiber optic cable and an optoelectronic device and a method of fabricating the same are described. In one aspect, a connector system comprises an optical waveguide and an optical turn assembly. The optical waveguide has a first end and a second end. The first end of the optical waveguide is connectable to the fiber optic cable in an orientation aligned with a line-side connection axis. The optical turn assembly has a first optical port that is connected to the second end of the optical waveguide in an orientation aligned with a device-side connection axis, a second optical port that is oriented to communicate optically with the optoelectronic device along a device communication axis substantially intersecting the device-side connection axis, and an optical turn system that is operable to guide light along a path between the first optical port and the second optical port.

Waveguide based optical coupling of a fiber optic cable and an optoelectronic device

A power supply and control circuit is provided for driving a fluorescent lamp from a low voltage DC power source such as a battery. A DC-to-AC inverter coupled to a switching regulator converts low DC voltage into a higher AC voltage for driving the fluorescent lamp. In one embodiment, the lamp is included in a feedback loop which includes a circuit for producing a feedback signal indicative of the magnitude of current conducted by the lamp. In another embodiment, the lamp is symmetrically driven by isolating the lamp from the driving circuitry and indirectly deriving the feedback signal. The feedback signal is applied to the switching regulator to produce in the lamp a regulated current and, hence, a regulated lamp intensity. The magnitude of the lamp current can be adjusted to enable the intensity of the fluorescent lamp to be smoothly and continuously varied (without 'dead-spots' or 'pop-on') over a chosen intensity range, including if desired, from substantially full OFF to full ON. When the lamp is symmetrically driven, the lamp is illuminated in a more uniform manner long the entire length of the tube. A method for driving a fluorescent lamp from low voltage DC power source is also provided.

Fluorescent lamp power supply and control circuit for wide range

A power-supply and control circuit is provided for driving a fluorescent lamp from a low-voltage direct current (DC) power source such as a battery. The circuit includes a converter that converts low-voltage DC to high voltage alternating current (AC). The converter includes a feedback ceramic step-up transformer that amplifies the AC signal to a level sufficient to illuminate the lamp, and also provides a feedback signal that can be used to monitor the resonance frequency of the transformer. The power supply and control circuit also includes a first feedback loop that regulates the lamp current amplitude and a second feedback loop that forces the converter to operate at the transformer's resonant frequency.

Fluorescent-lamp excitation circuit with frequency and amplitude control

Power supply and control circuits are provided for driving a fluorescent lamp with a differential drive voltage from a low voltage DC power source. In one embodiment, the lamp is driven by a transformer having a primary and two independent secondary windings which produce the differential drive signal. A feedback signal indicative of the magnitude of current conducted by the lamp is produced from one of the secondary windings that is coupled to the control circuit so that the feedback signal is directly proportional to the energy required to light the lamp. In another embodiment, the lamp is driven by two independent transformers that are both driven by the control and drive circuit. The two secondary windings are each connected to one end of the lamp so that the lamp is driven by a differential drive signal. One of the secondary windings is also coupled to the control and drive circuit to provide a feedback signal indicative of the magnitude of current conducted by the lamp.

Methods and apparatus for obtaining floating output drive to fluorescent

A key ring opener for spreading apart the adjacent end and intermediate portions of a split key ring that are spring-urged against each but are spreadable to allow a key to be placed on or taken off the ring. The opener includes an annular band having sharp circumferential wedging edges and is adapted to encircle such a key ring in the same way as a key, and along with keys on the ring, and a wedging bar extending diametrically of the band and having sharp wedging edges. The opener is slipped on and off the key ring like a key but is easier to do because of the sharp circumferential edges. While on the key ring, the bar can be wedged, again because of its sharp edges, between adjacent segments of the ring, ahead of a key, thereby to spread the segments apart. Thereafter, the band is rolled between the thumb and forefinger causing the bar to leverage the segments of the key ring farther apart thereby to facilitate entry and removal of a key to and from the ring. In addition to being small and lightweight, another valuable feature is that the opener will not come off the ring while the opener is facilitating key entry and removal although it can easily be removed if desired.

Key ring opener and method of use

A power-supply and control circuit is provided for driving a fluorescent lamp from a low-voltage DC power source such as a battery. In typical lamp-driving circuits, a step-up transformer is used to apply well known magnetic techniques to achieve the low-to-high voltage conversion required by the lamp. The present invention uses a new approach, applying piezoelectric characteristics of certain ceramic materials to replace the magnetic transformer. Resonant characteristics of such ceramic materials permit them to be self-resonated. A DC-to-AC converter coupled to a switching regulator converts low DC voltage into a higher AC voltage for driving the fluorescent lamp. In one embodiment, the lamp is included in a feedback loop which includes a circuit for producing a feedback signal indicative of the magnitude of current conducted by the lamp. The feedback signal is applied to the switching regulator to produce in the lamp a regulated current and, hence, a regulated lamp intensity. A method for driving a fluorescent lamp from a low-voltage DC power source is also provided.

Fluorescent-lamp excitation circuit using a piezoelectric acoustic

A power supply and control circuit is provided for driving a fluorescent lamp from a low voltage DC power source such as a battery. A DC-to-AC inverter coupled to a switching regulator converts low DC voltage into a higher AC voltage for driving the fluorescent lamp. The lamp is included in a feedback loop which includes a circuit for producing a feedback signal indicative of the magnitude of current conducted by the lamp. The feedback signal is applied to the switching regulator to produce in the lamp a regulated current and, hence, a regulated lamp intensity. The magnitude of the lamp current can be adjusted to enable the intensity of the fluorescent lamp to be smoothly and continuously varied (without 'dead-spots' or 'pop-on') over a chosen intensity range, including if desired, from substantially full OFF to full ON. A method for driving a fluorescent lamp from a low voltage DC power source is also provided.

Fluorescent lamp power supply and control unit

In a process of downhole drilling in an open hole, where the drill bit has struck a lost circulation zone in the wall of the formation, and mud circulating through the annulus during drilling has been lost into the zone and therefore circulation of the mud has been lost, the process for locating the depth of the lost return zone would include the steps of (a) detecting a drop in the mud level within the annulus of the drill casing to a central depth; (b) introducing a quantity of lighter fluid such as 8.5 pound salt water into the annulus of the borehole so that the annulus becomes filled with the lighter fluid; (c) closing off any flow of fluid out of the annulus substantially at the level of the earth's surface; (d) pushing a quantity of the mud in the annulus into the formation by the weight of the lighter fluid flowing into the annulus; from the distance that the mud fell in the annulus, calculating the height that the mud did not drop in the annulus in order to have the same hydrostatic head of the lost return zone depth; following the establishing of the hydrostatic head, reading the gauge pressure of 5.45 pounds for every barrel pumped into the lost return zone; and multiplying the number of barrels required to get the hydrostatic multiplied by 5.425 divided by 0.052 and divided by 0.15 (fracking weight) will equal the depth of the lost return zone.

Process for finding the depth of a lost return zone

In a process of downhole drilling in an open hole, where the drill bit has struck a lost circulation zone in the wall of the formation, and mud circulating through the annulus during drilling has been lost into the zone and therefore circulation of the mud has been lost, the process for reestablishing circulation downhole would include the steps of (b) closing off any flow of mud out of the annulus substantially at the level of the earth's surface; (a) introducing a quantity of lighter fluids such as salt water into the annulus so that the annulus becomes filled with the lighter fluid; (c) pushing a quantity of the mud in the annulus into the formation by the weight of the lighter fluid in the annulus, thus lowering the weight of the column of fluid in the annulus; (d) in calculating the mud weight necessary to circulate out the heavy mud with the lighter fluid; and introducing the lighter weight mud into the hole and into the drill pipe, for allowing the heavier mud to circulate up through the annulus to be replaced by the lighter mud.

Process for reestablishing circulation in a lost return zone

To control a motor, a pulse width modulated signal from a computer is fed to a capacitor which stores each pulse as a voltage proportional to the width of the pulse, the capacitor being reset to zero by a leading edge reset circuit. The voltage on the capacitor is sampled by a sample/hold circuit the output of which is fed to a converter which converts the voltage signal to a frequency signal exponentially related to the voltage, and hence to the pulse width. The converter then powers a driver which drives the motor. The exponential relationship between the pulses and the signal fed to the motor permits a large variationin the frequency signal based on a small variation in pulse width and hence permits accurate control of the motor.

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Palo Alto, CA, United States of America

James M Williams