Abstract: Conductive plastic resistance element having particles of conductive material embedded therein and projecting therefrom for reducing variations in contact resistance in a potentiometric device in which the element is employed. The element is made by processing carbon powder, resin, solvent and conductive phases to form a paste, applying the paste to a substrate, and curing the paste to drive off the solvent and form a film, with the conductive phases rising to the surface of the film and becoming embedded therein.

Abstract: A switching element, specifically an encoder element, is fabricated by forming a conductive track on an insulative substrate, and then screen printing an insulative layer on the track in a predetermined pattern that forms a contact array that comprises a plurality of conductive contacts separated by nonconductive areas. The substrate may be a polymeric resin, and the track comprises (a) a copper base layer formed on a surface of the substrate in the configuration of the track, (b) a first metal-plated layer, preferably of nickel, on the base layer, and (c) a second metal-plated layer, preferably of gold, on the first metal-plated layer. The insulative layer is formed of a thick film dielectric material comprising a difunctional monomer (e.g., diallyl isophthalate), a glycol ether ester (e.g., ethylene glycol monobutyl ether acetate), an inorganic filler (e.g., BaSO4), and an acetate surface modifier (e.g., an ethyl acrylate/ethylhexylacrylate copolymer).

Abstract: An ablative catheter assembly whose electrode is completely covered by a buffer layer. The buffer layer prevents areas of high current density at the surface of the catheter tip, which helps to reduce popping and clotting. The buffer layer may be in the form of a conductive fluid (such as saline solution) pumped into a cavity surrounding the electrode. In this case, the conductive fluid couples the electrode to the surrounding tissue so that RF energy will pass from the electrode to the tissue, thereby effecting ablation. Also, the buffer layer may be in the form of a porous coating which covers an electrode tip. In this case, blood or fluid which infuses the porous coating couples the electrode tip to the surrounding tissues to be ablated.

Abstract: A thick-film switch element includes a high-temperature glass frit fused to a non-conductive substrate. A cermet layer having a low-temperature glass matrix is fired in a conventional furnace to sink into the glass frit layer such that the resulting thickness of the switch element layer is approximately equal to the original thickness of the glass frit layer. The wet print thickness of the cermet layer is controlled upon application of the cermet to the glass frit. The glass frit and cermet are fired at a controlled temperature and duration to achieve a fired print thickness of the cermet above the surface of the glass frit having a pre-determined value. In one embodiment, the non-conductive substrate is a metal, such as stainless steel.

Abstract: A thermally fused resistor arrangement wherein a resistor is electrically connected at one end to a first resistor terminal and at an opposite end to a second resistor terminal. A solder loop is provided to make the electrical connection between one end of the resistor and its corresponding resistor terminal. A portion of the solder loop is positioned in contact with an electrically insulated portion of the surface of the resistor, preferably corresponding to the hot spot of the resistor, and a thermally conductive medium is provided to thermally and mechanically attach the solder loop to the electrically insulated portion of the resistor surface. The portion of the solder loop thermally attached to the resistor is operable to melt when the temperature of the resistor increases to within a predefined temperature range, thereby electrically disconnecting the end of the resistor from its corresponding resistor terminal.

Abstract: A three wire potentiometric liquid level sensor for measuring liquid levels in a container is disclosed. The sensor includes a conductive strip, a float, a contact means attached to the float, a resistive strip, and a conductive rod buried beneath an insulator. A second embodiment of the invention includes a first conductive strip, a second conductive strip, a float, a contact means attached to the float, and an insulating rod. The sensor produces a resistance directly proportional to the liquid level in the container.

Abstract: A thick-film switch element includes a high-temperature glass frit fused to a ceramic substrate. A cermet layer having a low-temperature glass matrix is fired in a conventional furnace to sink into the glass frit layer such that the resulting thickness of the switch element layer is approximately equal to the original thickness of the glass frit layer. The exposed surface of the resulting thick-film switch element product is substantially smooth and the joint between the low-temperature cermet layer and the high-temperature glass frit layer is substantially uniform.

Abstract: A two wire and a three wire resistive fluid level sensor for measuring fluid levels within a container are disclosed. The sensor includes a plurality of resistors connected in series. The sensor produces an output signal by providing a short circuit to the circuit nodes between the resistors so that a stair-step output signal is created as the float moves in conjunction with the liquid level in a container. The value of the resistances can be varied in order to accommodate various cross-sectional tank contours and thus produce a usable, readily and easily configurable sensor. The structure of the sensors enables measurement of depth variances far in excess of prior art sensors.

Abstract: A liquid level sensor for sensing liquid levels within a container is disclosed. The sensor includes a conductive plastic resistor and conductive plastic conductors deposited onto a thin polymer insulator. The conductive plastic resistor is a potentiometric resistive track which is electrically contacted at points along the length of the resistor by a contact assembly attached to a float. The polymer insulator is attached to a conductive support member or conductive strip disposed substantially vertically in the liquid. The float is disposed about the conductive strip. The contacts provide a short circuit between the resistive strip and conductive strip and thereby provide a resistive circuit connection analogous to the wiper of a potentiometer.

Abstract: A three wire potentiometric liquid level sensor for measuring liquid levels in a container is disclosed. The sensor includes a conductive strip, a float, a contact means attached to the float, a resistive strip, and a conductive rod buried beneath an insulator. A second embodiment of the invention includes a first conductive strip, a second conductive strip, a float, a contact means attached to the float, and an insulating rod. The sensor produces a resistance directly proportional to the liquid level in the container.

Abstract: A rotary digital contacting encoder (FIG. 1) including a base (5), comprising - a base epoxy disk (501) with three external, pre-molded in place, connector pins (P.sub.1 -P.sub.3) on its exterior side extending through it, and a conductive layer in the form of two concentric layer rings (502 & 503; FIG. 4); and - an encoder element made of a "Kapton" insulating substrate (510) carrying two, like concentric cog rings (511B & 511A; FIGS. 3 & 7) on its top side. Conductive vias (512 & 513) electrically interconnect each respective cog ring with its respective conductive layer ring and its respective external connector pin, the vias forming conductive paths through the insulating substrate between the conductive layer and the cog rings. The presence of the conductive layer 502/503, which can be screen printed on the base disk, greatly simplifies the relative alignment of the encoder element, conductor pads and terminals.

Abstract: A rotary digital contacting encoder (FIG. 1) including a base (5), comprising--a base epoxy disk (501) with three external, pre-molded in place, connector pins (P.sub.1 -P.sub.3) on its exterior side extending through it, and a conductive layer in the form of two concentric layer rings (502 & 503; FIG. 4); and--an encoder element made of a "Kapton" insulating substrate (510) carrying two, like concentric cog rings (511A & 511B; FIGS. 3 & 7) on its top side. Conductive vias (512 & 513) electrically interconnect each respective cog ring with its respective conductive layer ring and its respective external connector pin, the vias forming conductive paths through the insulating substrate between the conductive layer and the cog rings. The presence of the conductive layer 502/503, which can be screen printed on the base disk, greatly simplifies the relative alignment of the encoder element, conductor pads and terminals.

Abstract: A fuel level sensor 16 comprises a vertical member 20 and float 22 wherein said vertical member 20 comprises a steel substrate 26 encased in porcelain 28 with a thick film cermet resistive track 34 deposited thereon. A nickel deposit 36 at the bottom portion of the vertical member 20 facilitates electrical continuity between the substrate 26 and the resistive track 34 such that the substrate acts as a buried conductor enabling proportionality between magnitude of resistance and liquid level while diminishing the likelihood of conductor erosion and float interference.

Abstract: A method of trimming a resistance element is disclosed which comprises cutting transversely into one side of the element until the measured total resistance of the element increases by a fraction 1/N of a fixed percentage of a desired total resistance value. The fraction 1/N is approximately equal to the path length of the resistance element divided by the designed width of the transverse cut and the fixed percentage is equal to the percent deviation of the initial total resistance of the element from a nominal, desired resistance value. After the transverse cut is made, a longitudinal-type cut is made at a distance, equal to the length of the transverse cut, from the edge of the element having the transverse cut to isolate a portion of the element from the remainder of the element so that the isolated portion has the desired total resistance. This method is particularly suitable for use with computer controlled laser trimming systems used to mass produce resistance elements.

Abstract: An electrical resistance element for a variable resistance device, such as a thick film resistance element, and a method of making the element and a device utilizing the element, such as a potentiometer, is described. The resistance element comprises a single resistance material for use as a resistance path for a contact wiper in a variable resistance device and has a selected series of generally transverse cuts made in at least one section of the resistance material of the element. The cut section(s) provides an increased current path length through the element whereby the total resistance of the element is increased. Also, the cut section(s) provides the resistance element with a resistance function which can be adjusted to vary over a wide range of resistance values depending on the length, width, and number of the cuts.

Abstract: A cermet resistor element utilizing a silver-gold alloy to improve the contact resistance variations and the method of making the element are disclosed. A gold resinate and a silver resinate are mixed with the noble metal resinates and glass frit to make a cermet material. The mixture is heated to drive off the organic resinate materials and to alloy the silver and gold. The resultant material is ground to a powder, reheated and reground. The powder is mixed with a volatile material to form a paste which can be applied to a substrate to form the resistance element. The element is heated to drive off the volatile material and fuse the glass into a solid mass. The silver and gold form a silver-gold alloy during the process and settle on the top surface of the element in globules and improve the contact resistance variations of the element.

Abstract: A method of forming an electrical network package in which a B-stage thermosetting adhesive material is sandwiched between and adheres together a substrate bearing a network of electric circuit elements, and a protective superstrate. The component package is first heated sufficiently to initiate the formation of the adhesive into a gel. The package may then be cooled, and is momentarily compressed in order to flow the adhesive material into sealing relation with the electric network and to inhibit relative slippage between the substrate and superstrate followed by further heating to fully cure the adhesive.Except for the momentary compression, the entire curing sequence is performed without the application of external pressures, thereby considerably simplifying the requisite machinery. The method is adaptable to mass production techniques by employing a single continuous adhesive tape and lead frame in connection with a multiplicity of substrates.