Abstract: A rotary actuator derives its power from a synchronous motor preferably of the AC type providing constant output speed, and from a non-synchronous motor, preferably of the DC type, in a helper capacity to provide additional torque for a load. Use of certain types of non-synchronous motors to provide a portion of the maximum torque is cheaper than using a synchronous motor whose size is adequate for the maximum torque requirement. A torque limiting clutch which couples the non-synchronous motor output to the synchronous motor output allows the non-synchronous motor to run compatibly with the synchronous motor. A hysteresis coupling type of torque limiting clutch is preferred. In a preferred embodiment, both of the motors drive a gear train, with the non-synchronous motor coupled to the gear train by the torque limiting clutch.

Abstract: An interface circuit is designed to connect a first logic circuit such as a microcontroller with a second similar microcontroller using three wires and allowing for simultaneous transfer of data from each of the microcontrollers to the other. A transmitter element in each interface circuit has a bias resistor which cooperates with a pull-up resistor in the other interface circuit to provide an indication for one of the logic circuits when the other of the logic circuits and its associated interface circuit loses power or when one of the three connecting wires is disconnected.

Abstract: A display system for dynamically indicating the status of conditions of a physical system shows as background on a raster display unit, a sketch of the physical system with text indicating the status of the various conditions juxtaposed to the sketch. In the preferred embodiment, the text for each condition is placed adjacent the general area on the sketch to which the condition pertains. It is intended that this display system will be implemented on a general purpose computer system by executing software which converts the computer system into the display system.

Abstract: A circuit for detecting whether the level of an electrical signal having a preselected polarity is above a preselected value, is powered by DC of the opposite polarity. This prevents current leakage within the detector circuit from simulating the level of the electrical signal. Such a circuit is particularly suited for detecting the current level provided by a flame sensor in a combustion control system. The preferred embodiment has a capacitor which is charged by the circuit and then discharged by the electrical signal. The time required to discharge the capacitor to a preselected level indicates the level of the electrical signal. A second embodiment uses a comparator in a feedback loop which allows sensing the level of a voltage outside of the voltage range defined by the comparator's power supply.

Abstract: A flow disconnector has an intermediate chamber connected between inlet and outlet check valves. A diaphragm controls a venting valve for the intermediate chamber which is designed to empty the intermediate chamber when the difference between inlet pressure and intermediate chamber pressure becomes too small. To prevent unnecessary emptying of the intermediate chamber, a pressure stabilizer is connected between the inlet and the intermediate chamber. The stabilizer holds the pressure in the intermediate chamber below the inlet pressure by an amount sufficient to prevent unnecessary emptying of the intermediate chamber.

Abstract: A burner control system with an interrupted or intermittent type of pilot burner has a special feature allowing transitions between a pilot flame hold state where the pilot flame only burns and the run state where the main burner is operating. Each transition to the pilot flame hold state from the run state comprises a brief period in which presence of the pilot flame is assured while the main flame is extinguished. Transitions to the run state from the pilot flame hold state may proceed directly through the main flame establishment period to the run state, thereby eliminating the time-consuming purging and pilot flame ignition phases.

Abstract: An annunciator for the conduction status of individual switches wired into a series circuit records this status as status history at regular intervals in a memory. The status history is preferably recorded as individual entries having the identification number of an open switch along with a time stamp specifying the length of time which that switch has been open. The current entry is recorded in the memory and a new entry started each time the switch for which an entry in the memory is being created closes or a switch currently receiving power opens. A controller separate from the annunciator generates a request signal and provides a request time value to the annunciator specifying the time which has elapsed since the request condition was detected. The annunciator uses the request time value to determine the probable switch conduction status at the time of the request.

Abstract: An annunciator for the status of interlock switches connected into a series circuit for supplying power from a power source to a load, includes a memory recording the status of each switch at a selectable instant. A plurality of display elements are arranged in a pattern corresponding to the pattern of the interlock switch circuit. A manually operable switch allows a user to select for graphically showing with the display either the switch status recorded by the memory or the current status of the switches. The signals controlling the display are conditioned so that the particular display element assigned to the first out switch as recorded in the memory flashes to indicate the switch closest to the power source which was not conducting at the selectable instant.

Abstract: A knob accessory for a round thermostat of the type having a centrally located thermostat adjustment knob, has a relatively large diameter which allows easier adjustment of the thermostat setting for people who have difficulty in rotating an adjustment knob having detents to indicate thermostat settings. The knob accessory latches onto the standard adjustment knob with a detent mechanism which also allows removing the knob.

Abstract: A recovery algorithm for a setback thermostat uses the intersection of the space temperature with a sloped recovery temperature line which approximates the change in temperature as a function of time during recovery of the temperature controlled space from a setback temperature, to determine the time at which recovery to the occupancy temperature should begin. The thermostat starts recovery when the current space temperature crosses the recovery temperature line. A useful feature of the apparatus and method which implement the invention, computes and constantly updates the slope of the recovery temperature line. The update of the recovery temperature line slope is based on miss time, i.e., the time between actually achieving the desired next set point temperature and the next set point time associated with the next set point temperature.

Abstract: An electric power consuming system such as the lighting in a building has local control units for adjusting the power consumed by a preselected load or loads associated with each local control unit. The control units generate a selectable control voltage which has a first range specifying to the loads that no power should be consumed by the loads with voltage outside the first range specifying by its level the amount of power which the loads should draw. The system also includes energy management apparatus whose output is connected across the output of the control units and which can limit the power individual control units can specify to their loads. The invention comprises an interface circuit which connects the energy management apparatus to the control units and translates control voltages from the energy management apparatus falling within a second voltage range within the first range of the selectable control voltage, to a voltage falling outside the first voltage range.

Abstract: An etching and fluorinating treatment is disclosed for modifying the surface properties of magnetic data storage media and sliders for magnetic data transducing heads. Media enclosed within a plasma chamber is first exposed to an argon plasma for cleaning, then exposed to a plasma mixture including argon with either fluorine or carbon tetrafluoride, maintained at a pressure of approximately half of atmospheric pressure, at a temperature of about 100.degree. C. An electrical field is generated for forming argon, carbon and fluorine ions. The argon ions etch the carbon overcoat of the disc, while the carbon and fluorine ions combine with the carbon to form extended chain fluoropolymers, and also penetrate the carbon layer. Sliders are treated in a plasma mixture of argon and CF.sub.4. During such treatment, carbon and fluorine ions penetrate exposed surface areas of the slider, and form a reaction product of solid lubricant film.

Abstract: A wiper guide assembly, mounted at the free end of a workpiece carrying arm, can be selectively released to position a neoprene wiper blade against a lapping surface, and retracted whereby the blade is lifted away from the lapping surface. The wiper blade is located just ahead of a workpiece supported by the arm, and between the workpiece and a source of abrasive slurry supplied to the lapping surface. When retracted, the wiper blade is spaced apart from the lapping surface to expose its associated workpiece to the abrasive slurry, permitting more rapid removal of material. When the assembly is released, the wiper blade contacts the lapping surface in a wiping engagement, to guide or divert slurry away from the workpiece, whereby the lapping surface contiguous with and about the workpiece is comparatively free of abrasive slurry.

Abstract: A lapping plate is selectively textured for improved useful life and greater abrading consistency. Glass beads are serially propelled onto a lapping surface of the lapping plate in order to form spherical cavities of generally uniform size and distribution, and of a desired density. The cavities provide discontinuity in the lapping surface which substantially prevents workpiece hydroplaning. The cavities also receive loose abrading grit, workpiece fragments and other contaminants, resulting in more smoothly machined workpiece surfaces. Use of the lap plate with cavities also has been found to improve the co-planarity of composite magnetic transducing heads.

Abstract: Servo data, including three types of servo patterns distinguishable by phase, are stored in concentric servo tracks on a magnetic information storage disk. Each servo track includes a plurality of only one type of pattern, with consecutive tracks arranged in a repeating sequence of the three servo pattern types. For phase recognition, the pattern types further are arranged in a repeating sequence of angular sectors, each sector having a plurality of but one type of pattern. The servo patterns in a given storage track thus are always angularly offset from the servo patterns in the next adjacent tracks. This permits the use of servo patterns having a radial dimension greater than the separation between adjacent tracks, increasing servo signal reliability and transducer dynamic range.

Abstract: A thin film magnetic data transducer carried on the end of a conductive flyer has its magnetic pole electrically connected to the flyer to prevent electrostatic discharges between the flyer and the pole tip from eroding the pole tip. The winding of the transducer is also electrically connected to the flyer either through a high resistance, through a diode with high forward and reverse voltage drops, or through a fusible link, so as to bleed off static charges on the winding without their arcing through to the magnetic pole and damaging the insulation between the winding and the magnetic pole. These embodiments avoid any degrading of the data readback signal.

Abstract: Apparatus is shown for mixing and dispensing an epoxy adhesive. An epoxy resin and its associated curing agent are simultaneously loaded from separate cartridges into a length of flexible PVC tubing, part of which is contained between a rotor and a stator. Bearings, mounted rotatably about the rotor, engage and travel along the tubing as the rotor is revolved, each bearing compressing the tubing at its point of engagement. The tubing, repeatedly compressed and released by each bearing in succession, kneads the epoxy resin and curing agent into a homogeneous mixture. From the tubing, the epoxy mixture is deposited on a moving carrier tape and forms a continuous bead. Downstream, a control tape is spaced apart from the carrier tape and moves in the opposite direction. As the bead encounters the control tape, the control tape removes part of the bead material from the carrier tape and plastically forms the remaining mixture into a film of a uniform thickness substantially less than the bead diameter.

Abstract: A method and article of manufacture allows great accuracy in machining the edge of a face on a prism to a predetermined position respective a feature carried on the face and formed by deposition of insulating material. The preferred application for this invention is in accurately machining the transducing surface of a disk memory transducer assembly so that the throat height of the thin-film head carried on an end face of the assembly has a precise value.