Abstract: The electrical pin lead structure and brazing technique of the present invention provide a brazed lead in a sensor that adheres well to a semiconductor substrate while facilitating lateral flexibility without joint fatigue or breakage. In one example embodiment, the pin lead includes a coil head that is brazed to a silicon layer on a sapphire substrate using a silver-copper-palladium braze material. An advantage to this approach is the ability to both braze the pin lead to the diaphragm and seal the diaphragm to the ceramic backing plate with a high temperature glass in a single process step. Further, the palladium in the braze composition is a factor in reducing surface tension between the metal lead and semiconductor substrate during cooling to avoid stress fractures in the substrate.

Abstract: The electrical pin lead structure and brazing technique of the present invention provide a brazed lead in a sensor that adheres well to a semiconductor substrate while facilitating lateral flexibility without joint fatigue or breakage. In one example embodiment, the pin lead includes a coil head that is brazed to a silicon layer on a sapphire substrate using a silver-copper-palladium braze material. An advantage to this approach is the ability to both braze the pin lead to the diaphragm and seal the diaphragm to the ceramic backing plate with a high temperature glass in a single process step. Further, the palladium in the braze composition is a factor in reducing surface tension between the metal lead and semiconductor substrate during cooling to avoid stress fractures in the substrate.

Abstract: A sensor operable at temperatures in excess of 400° C. is described. The sensor of the present invention operates without fluid fill, is non-porous, non-contaminating, and has no exterior exposed metallic components. The sensor includes a non-porous, impermeable sensing diaphragm that may be positioned in direct contact with fluids in an ultra-pure environment. The non-porous surface may be comprised of a layer of single crystal sapphire that is glassed to a backing plate. The sensor of the present invention is suitable for use in a chemically inert pressure transducer module for sensing pressures and/or temperatures in process fluids and may be molded directly into the high temperature plastic housing of the pressure transducer module.

Abstract: A non-contaminating pressure transducer module having an isolation member is disclosed. The isolation member isolates a pressure sensor within the transducer module from exposure to ultra high purity fluids flowing through a conduit in the module without significantly affecting the accuracy of the pressure measurement. The transducer module may be positioned within a fluid flow circuit carrying corrosive materials, wherein the pressure transducer module produces a control signal proportional to either a gauge pressure or an absolute pressure of the fluid flow circuit. The pressure transducer module of the present invention also avoids the introduction of particulate, unwanted ions, or vapors into the flow circuit.

Abstract: A non-contaminating pressure transducer module having an isolation member is disclosed. The isolation member isolates a pressure sensor within the transducer module from exposure to fluids flowing through a conduit in the module. The transducer module may be positioned in-line within a fluid flow circuit carrying corrosive materials, wherein the pressure transducer module produces a control signal proportional to either a gauge pressure or an absolute pressure of the fluid flow circuit. The pressure transducer module of the present invention also avoids the introduction of particulate, unwanted ions, or vapors into the flow circuit.

Abstract: A non-contaminating pressure sensor module having an isolation member is disclosed. The isolation member isolates a pressure sensor within the transducer module from exposure to fluids flowing through a conduit in the module. The transducer module may be positioned in-line within a fluid flow circuit carrying corrosive materials, wherein the pressure transducer module produces a control signal proportional to either a gauge pressure or an absolute pressure of the fluid flow circuit. The pressure transducer module of the present invention also avoids the introduction of particulate, unwanted ions, or vapors into the flow circuit.

Abstract: A non-contaminating flow meter having an isolation member is disclosed. The flow meter includes two pressure sensor transducers, located on opposite sides of a restriction in a conduit. Each of pressure transducers is isolated by an isolation member from exposure to fluids flowing through the conduit. The flow meter may be positioned in-line within a fluid flow circuit carrying corrosive materials, wherein the square root of the difference in pressure between the two pressure sensors is calculated to thereby determine the rate of flow within the fluid flow conduit. The flow meter compensates for changes in temperature within the fluid flow circuit and further activates an alarm if the pressure or flow rate within the fluid flow conduit exceeds or falls below a threshold level. The flow meter of the present invention also avoids the introduction of particulate, unwanted ions, or vapors into the flow circuit.

Abstract: A fiber-optic data-link used to interface a remote process variable sensor/transmitter to a local process control system includes a local light source module and a remote interface module interconnected by one or more optical fibers. Energy for operating the remote interface module and its associated process variable sensor/transmitter is provided by light energy transmitted from the local site to the remote site and converted at the remote site to an electrical signal. The local light source module and the remote interface module each may include a microcontroller.

Abstract: A light input energizes an optical transmitter providing a light output to a waveguide indicating a process variable. The transmitter has a process variable sensor generating a sensor output. An electrical circuit receives the sensor output and generates an electrical transmitter output indicating the process variable adjusted by a changeable parameter stored in the electrical circuit. The electrical circuit has an input energizing the circuit. An LED converts the electrical transmitter output to the light output. A gallium arsenide photodiode converts a first portion of received light into electrical energy provided to the energization input and converts a second portion of the received light into an electrical output controlling the stored parameter.

Abstract: A temperature sensing system has a signal means which provides a signal representative of a temperature responsive luminescence, where the luminescence has a characteristic time-rate-of-decay. A means for comparison is connected to the signal means and samples the signal during two time intervals, the first interval overlapping the second. The averages of the samples are compared to provide a difference signal representative of the difference between the two measured averages. Control means coupled to the comparison means provide an output representing the temperature as a function of the time-rate-of-decay, by adjusting the overlapping intervals so that the difference signal converges to a preselected limit.

Abstract: An isolator for use in pressure transmitters for isolating the process fluid being sensed from a sensor, comprises an isolating diaphragm that is thin, and made of a suitable corrosion resistant metal, such as tantalum, and which must be anchored to an isolator housing made of a substantially different metal such as stainless steel. Tantalum is very resistant to corrosion, and is a high melting point metal, which is substantially higher than the material comprising the sensor housing so direct welding is virtually impossible. The present invention relates to securing a support ring of the same metal as the diaphragm surrounding the cavity formed for the isolator fluid, preforming a thin metal diaphragm made of the selected material, and then welding the diaphragm and a ring overlying the diaphragm directly to the support ring.

Abstract: A temperature sensing system has a signal means which provides a signal representative of a temperature responsive luminescence, where the luminescence has a characteristic time-rate-of-decay. A means for comparison is connected to the signal means and samples the signal during two time intervals, the first interval overlapping the second. The averages of the samples are compared to provide a difference signal representative of the difference between the two measured averages. Control means coupled to the comparison means provide an output representing the temperature as a function of the time-rate-of-decay, by adjusting the overlapping intervals so that the difference signal converges to a preselected limit.

Abstract: An isolator for use in pressure transmitters for isolating the process fluid being sensed from a sensor, comprises an isolating diaphragm that is thin, and made of a suitable corrosion resistant metal, such as tantalum, and which must be anchored to an isolator housing made of a substantially different metal such as stainless steel. Tantalum is very resistant to corrosion, and is a high melting point metal, which is substantially higher than the material comprising the sensor housing so direct welding is virtually impossible. The present invention relates to securing a support ring of the same metal as the diaphragm surrounding the cavity formed for the isolator fluid, preforming a thin metal diaphragm made of the selected material, and then welding the diaphragm and a ring overlying the diaphragm directly to the support ring.

Abstract: A pressure transmitter is coupled directly to an industry standard flange adapter union having a standard bolt hole spacing. Small diameter isolator diaphragms are positioned on the transmitter housing at locations so that the industry standard flange adapter union which couple fluid pressure sources to act on the isolator diaphragms without an intermediate large flange or manifold as is presently required and using the fasteners for the adapter union to complete the coupling. The smaller isolaters fit within the bolt hole spacing of the industry standard adapter union.

Abstract: An isolating mount provides vibration isolation for a sensor that is sensitive to external vibration about a rotational axis thereof at low frequencies, and translational vibrations in all axes at high frequencies. The isolation mount comprises a frame surrounding the sensor, and includes a plurality of columnar or beam members which are flexible in shear and stiff in compression. The beam members have longitudinal axes which lie in a common plane, also defined by the X-Y axes of the sensor. Connector members to couple desired beam members between the frame and the sensor and other connector members couple other beam members from the frame to the main support structure. The beam members flex in both the X and Y axis and also the Z axis, which is perpendicular to the common plane, but because the beam members are very stiff in compression, the resistance to any rotational movement about the Z axis is high.

Abstract: A current-to-pressure (I/P) converter provides an output pressure as a function of the magnitude of a variable input DC current. The I/P converter includes a pressure sensor which produces a feedback signal representative of the output pressure. Based upon the feedback signal and the magnitude of the input DC current, an electrical control signal is produced which controls a device for varying the output pressure. The I/P converter also includes a circuit for generating a time-varying signal which is sent back over the current loop wires through which the input DC current flows. The time-varying signal provides an indication of whether the I/P converter is functioning properly. This permits diagnosis of possible causes of control system malfunctions without having to inspect the I/P converter itself.

Abstract: A non-contaminating pressure transducer module having an isolation member is disclosed. The isolation member isolates a pressure sensor within the transducer module from exposure to fluids flowing through a conduit in the module. The transducer module may be positioned in-line within a fluid flow circuit carrying corrosive materials, wherein the pressure transducer module produces a control signal proportional to either a gauge pressure or an absolute pressure of the fluid flow circuit. The pressure transducer module of the present invention also avoids the introduction of particulate, unwanted ions, or vapors into the flow circuit.

Abstract: A non-contaminating pressure transducer module having an isolation member is disclosed. The isolation member isolates a pressure sensor within the transducer module from exposure to ultra high purity fluids flowing through a conduit in the module without significantly affecting the accuracy of the pressure measurement. The transducer module may be positioned within a fluid flow circuit carrying corrosive materials, wherein the pressure transducer module produces a control signal proportional to either a gauge pressure or an absolute pressure of the fluid flow circuit. The pressure transducer module of the present invention also avoids the introduction of particulate, unwanted ions, or vapors into the flow circuit.