Abstract: A gas flow restriction device for restricting the flow rate of heated gas in a conduit. The flow restriction device is essentially a two piece assembly that includes a valve housing and a valve gate structure that sits within the housing. The valve housing has a first end, a second end and an open central passage extending from the first end to the second end. The open central passage includes a internally tapered section proximate its first end and an internally threaded section proximate its second end. The valve gate structure has a first end a second end, a externally tapered section proximate its first end and an externally threaded section proximate its second end. The valve gate structure passes into the open central passage of the valve housing so that the externally tapered section of the valve gate structure is disposed a predetermined distance within the internally tapered section of the valve housing.

Abstract: Apparatus for determining the physical uniformity of a charged drum surface wherein current signals are induced in sensing electrodes in response to variation in drum surface charge. The sensing electrodes are on a detector assembly which is movable toward the drum for inspection of the surface and movable away from the drum after inspection when the drum is to be ejected from the apparatus. The detector assembly is movable through another degree of freedom to accommodate irregularities in drum geometry encountered during rotation thereof. The detector assembly also is provided with structure for maintaining a predetermined spacing of the sensing electrodes from the drum surface during relative movement therebetween. The drum is received, held, and rotated by co-operation between a drum retention assembly and a drum clamping mechanism.

Abstract: A photographic film is adapted to provide visual record of the occurrence of a transient electrostatic or transient magnetic field by the inclusion of metallic patterns close to the film. The patterns are of a geometry to define gaps at which the fields are concentrated in a manner to interact with the film. The film exhibits a light spot at the gap, when it is developed, if a field of sufficient intensity is present during the test period. The film packet is intended primarily for inclusion in the shipping package for sensitive electronic devices to provide a visual record of exposures during shipment.

Abstract: A non contact voltmeter includes a multilayered structure adapted to configure a plurality of coupled capacitors in a manner to permit high speed operation. A high frequency input signal is applied to a plate capacitivity coupled to both the test object and a sensor. The structure is also configured to capacitivity couple the sensor directly to the test object. The structure allows for circuit configurations with low time constants permitting outputs at the input frequency as well as a small and inexpensive solid state configuration.

Abstract: A hand-held, low cost, low voltage surface resistivity meter is provided by a contact surface which is essentially independent of the geometry of the surface to be measured. The use of special materials for the contact surface permits increased accuracy to be achieved at low voltages. Recognition that readings shown simply to the power of 10 are fully useful in characterizing a measured material permits a low cost, low voltage arrangement for the meter.

Abstract: A dynamically balanced ion generator is provided which incorporates a detection screen and feedback loop to ensure that the number of positive and negative ions emitted from the generator are substantially equal. The detection screen is located between the ion generating electrodes and the exit port of the device, and is contructed of conductive material which captures a predetermined percentage of ions emitted by the electrodes. The detected imbalance is corrected through a feedback loop comprising an operational amplifier circuit, a low pass filter, a balance control comparator, variable duty cycle oscillator. By varying the duty cycle of the variable duty cycle oscillator, the voltage applied to the primary of a high voltage transformer is controlled such that the relative concentrations of positive and negative ions generated may be altered to compensate for any detected imbalance.

Abstract: An improved electrostatic fluid filter is disclosed which is particularly useful in high performance clean rooms for the semiconductor industry. The electrostatic fluid filter is tubular in design and has an inlet port for supplying fluid (e.g., liquid, air) to be filtered and an output port from which relatively pure fluid flows. The filter includes a high voltage conductor which is disposed along the axis of the tube and which is surrounded by a ridged polytetrafluoroethylene insulator. Fluid is directed along the length of the filter parallel to the conductor. Contaminating particles in the fluid are transformed into electrical dipoles and are attached to the high voltage conductor.

Abstract: An improved electrostatic filter particularly for use in high performance clean rooms for the semiconductor industry is achieved by forming a layer of wires in a "plane" having corrugations along an axis perpendicular to the axes of the wires. The "plane" is designed to mate with the corrugations of a mechanical filter placed immediately upstream in the air flow path. Alternate wires of the layer are maintained electrically at opposite polarities to strengthen the fields and the corrugations permit closer movement of particles to the wires without unacceptable constriction of the air flow. A multilayered filter produces attractive field configurations, like those achieved by corrugated single plane filters herein, in the absence of a corrugated geometry.

Abstract: The accuracy of measurements made to determine the extent of water vapor trapped upon encapsulation of an electronic device is significantly enhanced by carefully controlling the measurement technique employed. In particular, the encapsulant is generally punctured and the water vapor thus released is monitored. It has been found that to obtain an accurate measurement of the magnitude of the water vapor released, this measurement must be made within 0.1 second of the time of encapsulant punctured and released into a glass system. By using an absorption technique with suitable electronics, this time requirement is fulfilled and significantly more accurate quantitative measurements of entrapped water vapor are obtained.