Abstract: An electronic control circuit (10) for a gas oven including a hot surface igniter (24) which is heated through the application of electrical current to a temperature sufficient to ignite gas supplied through an electrically actuable gas valve (26). The applied current is regulated by a micro-controller (20) which controllably gates on a triac (14) while taking into consideration a sensed current level.

Abstract: A cam disc has a dual row of ratchet teeth on the periphery for dual rate of advancement by either of two oscillating motorized advance pawls. The disc has alternating high and low concentric cam tracks formed on one face. A plate is registered on the cam disc hub and has integrally formed plural resilient cam follower arms with each arm having a plastic cam track follower tip molded over the tip. The molded tips make contact with a stationary portion of the plate to limit follower travel when the cam is retracted by user movement of the shaft for setting the cam position. The high and low cam tracks engage adjacent follower arm pairs to effect a drop-to-make and drop-to-break action to each of a plurality of SPDT switches disposed for actuation by the cam followers.

Abstract: An ignitor for fuel gas burners formed of a plurality of spaced parallel filaments of SiC coated Carbon (C) high temperature brazed with Chromium Silicide in grooves provided in a refractory base block of Aluminum Oxide and Silicon Oxide. Terminal posts of IVIoSi are embedded in the high temperature braze. Stainless steel lead attachment pads are nickel-chrome brazed to the posts at a lower temperature. Removable notched graphite bridges and graphite hold-down blocks position the filaments during the high temperature brazing.

Abstract: A method is provided for producing plasma pinch X-rays usable in X-ray lithography. Ionized heated plasma is repeatably generated in a first area directly from solid material without exploding the latter. X-rays are generated in a second area by passing high current through the plasma causing radial inward magnetic field pinching. Accurate control and improved intensity performance, and greater flexibility in selection of X-ray emitting materials, are provided by the separation of the plasma generating and the X-ray pinch generating functions.

Abstract: A solid display is provided by a semiconductor switched between transparent and opaque conditions according to external removal of carriers from the conduction band for controlling absorption of light-energy. A semiconductor has an energy band gap affording a normally saturated conduction band in response to impinging light energy of a given range wavelength. The normally saturated condition of the semiconductor prevents further absorption, and enables light to pass thererthrough. The semiconductor is switched to an opaque condition by completing an electric circuit for removing carriers from the conduction band to enable further absorption of incident light in the semiconductor by raising additional carriers from the valence band to the conduction band.

Abstract: A system is provided for producing plasma pinch X-rays usable in X-ray lithography. Ionized heated plasma is repeatably generated in a first area directly from solid material without exploding the latter. X-rays are generated in a second area by passing high current through the plasma causing radial inward magnetic field pinching. Accurate control and improved intensity performance, and greater flexibility in selection of X-ray emitting materials, are provided by the separation of the plasma generating and the X-ray pinch generating functions. Common electrode structure is provided for plasma generating and for plasma pinching, which common electrode also provides a cylindrical plasma communication passage from the first to the second area, and provides an X-ray emission passage of desired axial orientation.

Abstract: A system is provided for producing plasma pinch X-rays usable in X-ray lithography. Ionized heated plasma is repeatably generated in a first area directly from solid material without exploding the latter. X-rays are generated in a second area by passing high current through the plasma causing radial inward magnetic field pinching. Accurate control and improved intensity performance, and greater flexibility in selection of X-ray emitting materials, are provided by the separation of the plasma generating and the X-ray pinch generating functions. Common electrode structure is provided for plasma generating and for plasma pinching, which common electrode also provides a cylindrical plasma communication passage from the first to the second area, and provides an X-ray emission passage of desired axial orientation.

Abstract: A diode is integrated on a common substrate with a thyristor to form a parasitic transistor in the gate circuit of the thyristor for amplifying gate current thereto. In addition, gate sensitivity is further enhanced by this formation because the injection efficiency across the thyristor anode-base junction is increased, thus reducing the amount of gate current necessary to trigger the thyristor. The diode cathode, diode anode and substrate form an emitter, base and collector, respectively, of the parasitic transistor. The junction formed by the substrate and the thyristor anode region is forward biased and supplies collector current for the parasitic transistor, this junction being inactive with respect to the junction formed by the substrate and the diode anode region. Thus gate current flowing through the diode to the gate of the thyristor is increased by the additional collector current afforded by the parasitic transistor.

Abstract: A Hall effect semiconductor device is provided with means for clipping or focusing emitted carriers to form a centralized columnated beam, and trimming means for accurately controlling the amount of magnetic deflection due to Lorentz force. Emitters from an emitter region travel through a base region under influence of an externally applied drift field toward a pair of spaced collector regions. The polarity of a perpendicularly applied magnetic field determines deflection of the carriers toward one or the other of the collector regions. The columnating means comprises a pair of spaced auxiliary collector regions intermediate the emitter region and the primary collector regions for collecting carriers not within a central angle or cone. A columnated beam is provided by carriers passing between the auxiliary collectors within the central angle or cone.

Abstract: A system is provided for producing plasma pinch X-rays usable in X-ray lithography. Ionized heated plasma vapor is repeatably generated directly from solid material by impingement of a plurality of circumferentially spaced laser beams to generate an annulus of plasma. X-rays are generated by passing high current through the annular plasma in an axial gap between the solid material target electrode and another electrode, causing magnetic field radial inward plasma pinching to a central constricted area further heating the plasma and emitting X-rays. A central axially directed laser may further heat the plasma in the pinched area.

Abstract: A power thyristor is provided with a pair of antiseries back to back diode junctions forming an open base transistor thermally coupled to the thyristor and electrically connected between the thyristor gate and cathode. The diode junctions shunt gate current above a given sensed temperature of the power thyristor, for protecting the latter by preventing turn-on thereof. The diode junctions have nonsymmetrical leakage current characteristics to insure protective shunting of forward gate drive in one direction but blocking leakage in the other direction to prevent draining a reverse charged phasing capacitor. The latter is thus charged beginning from the same starting reference point in each cycle whereby to insure accurate phase control in an AC gating system.

Abstract: A gate turn-off device is disclosed having a load current carrying power transistor regeneratively collector-base coupled with another transistor, and includes a third, shunting transistor providing high gain turn-off. The device is turned ON by signal current of one polarity applied to the base of the power transistor driving the latter into conduction to carry load current, and the device remains ON upon removal of the signal due to base drive supplied by the collector of the other transistor in the regenerative loop. A third transistor is connected to one of the collector-base junctions to shuntingly break the regenerative loop when the third transistor is biased into conduction, thus providing higher gain turn-off. A single ON-OFF control terminal is disclosed, as well as separate ON and OFF control terminals.

Abstract: A monolithically integrated gate turn-off device is disclosed comprising a vertical power transistor collector-base connected with a lateral transistor to form a regenerative loop. The device is turned on by signal current of one polarity applied to the base of the power transistor driving the latter into conduction, and remains ON upon removal of the signal current due to base drive supplied by the collector of the other transistor in the regenerative loop. The device is turned OFF by signal current of opposite polarity breaking the regenerative loop.

Abstract: An external resistance is presented between the gate and cathode of a thermally sensitive thyristor which varies in accordance with a changing voltage applied across the thyristor. The changing voltage sweeps the varying external resistance through its operating range which in turn expands the region of temperature sensitivity with respect to breakover voltage by sweeping the shifting curves of switching temperature vs. gate to cathode resistance for the thyristor. In preferred form, a field effect transistor (FET) (10) is connected between the gate (8) and cathode (4) of the thermally sensitive thyristor (6) and is biased by the same voltage supply applied across the thyristor. The FET presents an external gate to cathode resistance which varies in accordance with the changing bias level on the FET, which is the same changing bias applied across the thyristor. The range of variance of this added external resistance must be between 10,000 ohms and 1 megohm.

Abstract: Various circuits and combinations of radiant energy responsive transducer means such as photovoltaic diodes connected to the gate of a depletion mode FET whose source and drain are connected to the gate and cathode of a thyristor, are disclosed to provide a semiconductor switch which is triggered into conduction solely by a small amount of radiant energy, without the need for a second triggering energy source, and which also affords immunity to unwanted dv/dt and temperature induced turn-on. Various modes of operation are disclosed, including the thyristor self-triggering into conduction, and/or being of the light-activated type itself and being directly triggered by impinging light, and/or being triggered by the light-responsive diode bias, and/or being triggered by a small bias supplied from a second set of photovoltaic diodes connected to the thyristor gate. Other combinations are disclosed providing zero-cross firing.

Abstract: A gate turn-off device is formed by the integration of a lateral SCR and a vertical power transistor operating in parallel, with the latter carrying most of the load current whereby the former may be easily turned off which in turn terminates base drive to the transistor and thus the device is turned OFF.

Abstract: A gate turn-off device is formed by the integration of a power transistor with a lateral thyristor. The thyristor has a split emission path from its emitter, part of the emitter current completing a regenerative loop to maintain conduction after removal of a gating signal, and the remainder of the emitter current supplying base drive to the power transistor to render the latter conductive. In the ON state of the device, most of the load current flows through the power transistor, with only a small holding current flowing through the thyristor. Because of the low level of holding current, the thyristor is easily turned off by a small negative gating signal, breaking the regenerative loop, thus terminating emitter current whereby there is no base drive for the power transistor and hence the device is OFF.

Abstract: A transducer is disclosed which provides a digital indication of a sensed analog condition without the need of an analog to digital (A/D) converter or a comparator. A condition responsive element having a true abrupt switching characteristic at a known breakover voltage as a function of a condition being sensed is biased by a voltage source preferably supplying a periodic voltage as a known function of time. The point during the voltage source cycle at which the condition responsive element switches to its other state is determined by the sensed condition. Preferably, a clock of known frequency is enabled when the condition responsive element is in one of its states, whereby clock pulses are counted during an interval whose duration is determined by the sensed condition.

Abstract: A semiconductor device is disclosed which uses the phenomenon of "scattering limited velocity effect" for practical current limiting purposes. A monolithic chip of semiconductor material has a plurality of active spot regions or conduction channels formed by an encompassing inactive region which surrounds and separates each of the channels. The inactive region blocks current flow and performs a heat sinking function, the latter being necessary because of the high power density within the conduction channels at which the "scattering limited velocity effect" is exhibited.

Abstract: A semiconductor device is disclosed comprising a temperature sensitive thyristor thermally coupled to a power switching thyristor and electrically connected in parallel with the gate of the latter. The temperature sensitive thyristor senses the temperature of the power switching thyristor and automatically responds thereto above a predetermined temperature by shunting the gate current to prevent overheating of the power switching thyristor. The device may additionally include a second temperature sensitive thyristor having a lower switching temperature than the first mentioned thyristor and connected in series with the gate of the power switching thyristor whereby the latter may be triggered into conduction only within a defined temperature range bounded by the switching temperatures of the temperature sensitive thyristors. Normally off and normally on devices are also disclosed.