Abstract: Disclosed is electromagnetic transducer (10) that does not require complex analog to digital, digital to analog converters, microprocessors or large memory circuitry. The transducer has a helical tablet coil (22) with tap nodes (24) spaced between its end extremities (26). In one configuration, an oscillator (42) drives the tablet coil for simultaneously producing oppositely directed currents on opposite sides of selected taps, creating a moving fringing field (34) that is compatible with modern graphic display tablet technology. A control circuit (40) of the transducer has a closed-loop integrator (82, 106) for detecting the centroid of a received stylus signal (AC) from a stylus coil (36). Analog and digital versions of the integrator are disclosed.

Abstract: Disclosed is electromagnetic transducer that does not require complex analog to digital, digital to analog converters, microprocessors or large memory circuitry. The transducer has a helical tablet coil with tap nodes spaced between its end extremities. In one configuration, an oscillator drives the tablet coil for simultaneously producing oppositely directed currents on opposite sides of selected taps, creating a moving fringing field that is compatible with modern graphic display tablet technology. A control circuit of the transducer has a closed-loop integrator for detecting the centroid of a received stylus signal from a stylus coil. Analog and digital versions of the integrator are disclosed. In another configuration, the oscillator drives the stylus coil for variably coupling magnetic flux to the tablet coil, a receiver signal that is coupled from the end extremities being responsive to the position of the stylus coil and the taps selected.

Abstract: Disclosed is electromagnetic transducer that does not require complex analog to digital, digital to analog converters, microprocessors or large memory circuitry. The transducer has a helical transmitter coil with tap nodes spaced between its end extremities. An oscillator drives the coil for simultaneously producing oppositely directed current on opposite sides of selected taps, creating a moving fringing field that is compatible with modern graphic display tablet technology. A control circuit of the transducer has a closed-loop integrator for detecting the centroid of a received stylus signal. Analog and digital versions of the integrator are disclosed.

Abstract: A switch assembly includes an array of switches arranged on a substrate having a conductive pattern on a surface thereof defining a plurality of switch contacts. An apertured spacer is disposed adjacent the surface with an aperture being positioned in opposed relationship to each switch contact. A multi-conductive contact material is disposed to provide switch closure when forced through an aperture in the separator into engagement with a switch contact at a large number of separate conductive engagement regions. In one arrangement the multi-conductive contact material is a fine mesh woven wire screen stretched taut adjacent the separator while in another arrangement it is a uniaxially conducting material having a high density of parallel, spaced conductors extending perpendicular to the surface.

Abstract: An inexpensive, yet highly reliable, electrical switch contact assembly with excellent human factors considerations includes an electrical contact assembly having a plurality of switch positions, a cover plate disposed adjacent the switch contact assembly with an aperture for each switch position, and at each switch position an apertured key, a follower disposed within the key aperture, a cap containing the follower within the key aperture and key and follower springs biasing the key and follower respectively to provide separate and independent control over key actuation and switch contact closure forces. A contact engagement post of the follower may be accurately positioned above a switch contact notwithstanding variations in spring characteristics an a curvilinear engagement surface assures optimum distributed switch closure pressure for high reliability switch actuation.

Abstract: A keyboard switch assembly for use in telephones, calculators and the like positions a thin, flexible dielectric member with a switch closure conductive pattern printed thereon between substrate switch contacts and flexible bubble actuator mechanisms. The separate switch closure member permits the closure conductor pattern to be selected independently of constraints for proper bubble operation while permitting the flexible bubbles to be designed independently of requirements for switch closure patterns for optimum switch assembly design and operation.

Abstract: Highly durable coatings are formed by the photopolymerization of screen printing inks containing aryloxyalkyl acrylate monomers or prepolymers, a polymerizable diluent and a free-radical initiating system, such inks having a viscosity of 5,000 to 200,000 centipoises and a thixotropic index of from 1 to 6. The photopolymerizable inks are useful for coating substrates, such as printed circuits, and serve as solder masks and resists for electroless plating, electroplating and etching.

Abstract: Highly durable coatings are formed by the photopolymerization of screen printing inks containing aryloxyalkyl acrylate monomers or prepolymers, a polymerizable diluent and a free-radical initiating system, such inks having a viscosity of 5,000 to 200,000 centipoises and a thixotropic index of from 1 to 6. The photopolymerizable inks are useful for coating substrates, such as printed circuits, and serve as solder masks and resists for electroless plating, electroplating and etching.

Abstract: A process for making photoresists which comprises preparing a photopolymerizable layer of an addition polymer, an initiator system, and a polymerizable inhibitor, using a preformed macromolecular binding agent which is a copolymer of a first monomeric material containing one or more non-acidic vinyl-type compounds and a second monomeric material containing one or more alpha,beta-unsaturated carboxyl-containing monomers, wherein the ratio of the first monomer to the unsaturated carboxylic-containing monomer is sufficient to render the binding agent soluble in a dilute alkaline solution; thereafter exposing a portion of the photopolymerizable layer to actinic light; and washing said layer with a dilute aqueous alkaline solution to dissolve the unexposed portion of the photopolymerizable layer. Preferably, the photopolymerizable layer is supported on a metallic substrate prior to said washing step.