Abstract: A method and apparatus for controlling refrigerant gas pressure in a low pressure refrigeration system including a warm surface within a container. Liquid refrigerant is removed from the refrigeration system evaporator and sprayed on the warm surface, thereby vaporizing. The resulting pressure differential between the container and the evaporator causes the vaporized refrigerant to be returned to the evaporator through an open return line. The warm, surface is downwardly concave so that non-volatile liquid which had been mixed with the refrigerant can be collected from the bottom of the surface and transported to a location remote from the evaporator, thereby separating contaminants from refrigerant.

Abstract: A variable speed control system for a single phase AC induction motor wherein a controllable switch is in series with the main winding of the motor, while the auxiliary winding of the motor, which is in series with a capacitor, is continuously energized. The switch is opened whenever the current through the main winding passes through zero. While the switch is open, the back e.m.f. in the main winding is sensed to provide a measure of the speed of the motor. This is compared with a desired speed signal and the comparison is utilized to control closure of the switch. The speed of the motor then remains constant at the desired speed, even with a varying load.

Abstract: An arrangement for detecting a motor overload condition by examining the phase angle relationship between the motor voltage and current. As the load increases, the phase angle difference approaches zero. By measuring the zero crossings of the voltage and current and providing a signal representative of the time difference between these crossings, the phase angle relationship is determined and, accordingly, so is the motor load. Specifically, a saturable ferromagnetic core is utilized to detect the current zero crossings.

Abstract: A safety arrangement for an automatic door operator wherein the door edge has mounted thereon a stretched electrically conductive cable which, when deflected upon encountering an obstruction, will change the inductance of a loop of which the cable forms a part. A capacitor is in parallel with this loop so that the capacitor together with the inductance of the loop form a resonant tank circuit. The tank circuit is electrically driven by a voltage controlled oscillator. The phase of the loop current is compared with the phase of the voltage across the capacitor and the phase difference is utilized to control the voltage controlled oscillator to maintain the tank circuit in resonance (i.e, zero phase difference). The detection of a sudden change in phase difference, which occurs when the loop inductance is suddenly changed due to the encountering of an obstruction by the door edge, results in the generation of an obstruction signal for activating the safety feature of the door operator.

Abstract: An emergency light control and battery charging system utilizes a temperature compensated switched voltage regulator for charging the battery. Energization of the emergency light is effected through a field effect transistor which is turned on through a voltage doubler circuit enabled when there is a failure in the power supply. The system is arranged with a latch that insures that the light is not turned on when the battery is connected until after line power is initially applied. A low battery voltage detector insures that the battery is protected from a deep cycle discharge if line voltage is not restored.

Abstract: A method and apparatus for electronically pressure sealing and leak testing an idle centrifugal chiller system wherein a small positive differential is maintained between the internal refrigerant vessel pressure of the chiller system and the ambient atmosphere. This differential pressure is maintained by selectively applying heat to the refrigerant.

Abstract: A transient voltage surge suppressor including first and second clamping stages with a surge reactor between the stages. The first stage comprises a metal oxide varistor and the second stage comprises a silicon surge suppressor diode. The surge reactor comprises first and second coils wound with the same polarity on a single ferromagnetic core.

Abstract: An improved arrangement for controlling the speed and direction of rotation of a DC motor responds to a variable bipolar input signal. A bipolar threshold detector coupled to the motor is used for the selective triggering of a triac during the appropriate half wave polarity of an AC source. Triac failure is prevented by a protection circuit. The arrangement incorporates a speed servo and senses the voltage across the triac to detect the speed of the motor.

Abstract: An automatic door operator system is provided with a first potentiometer having its wiper arm coupled to a pivoting member whose angular position varies in accordance with the magnitude and direction of an obstructive load applied to the door. A second potentiometer is provided having its wiper arm coupled to a movable member whose position corresponds to the position of the door. The potentiometers are connected as voltage dividers and the voltages provided at their wiper arms are utilized for controlling the movement of the door.

Abstract: An electronically controlled sewing machine is provided with an arrangement for displaying a pictorial representation of a pattern to be sewn by the sewing machine. When the sewing machine user operates controls to alter the size and/or shape of the pattern, the display is correspondingly altered.

Abstract: A multiple pattern sewing machine is provided with a first group of switches which are always visible and functional for selecting a pattern from a first group of stitch patterns which the sewing machine is capable of sewing. A second group of switches is concealed beneath a cover member. Also concealed by the cover member is a plurality of information bearing pivotally mounted plates. The machine contains circuitry for sensing which of the plates is exposed and dependent thereupon, the second group of switches may be actuated by an operator for selecting a pattern from a second group of patterns which the machine is capable of sewing.

Abstract: The combination of an electronically controlled sewing machine and an auxiliary memory comprising pages of a book, or the like, each page having optical bar coded stitch pattern data printed thereon and in obvious association with a graphic representation of the actual stitch pattern. The coded data is sensed by a hand held optical reader which transfers the data, for a desired stitch pattern, to internal memory of the sewing machine.

Abstract: A sewing machine is provided with a hinging system which supports information bearing plates and a cover therefor. The plates are confined and concealed in a recess in the machine when the cover is closed and can pivot between positions in the recess and positions opposite the rear side of the cover when the cover is open.

Abstract: An arrangement for utilizing a single lead for communication and control between a controller and a switch-indicator pair. The switch and indicator are connected and the single lead is connected at a junction point of the switch and the control input of the indicator so that when the switch is closed the lead carries thereon a signal indicative of switch closure and the controller may utilize this same lead to provide a signal for controlling the energization of the indicator.

Abstract: A display system utilizing incandescent lamps arranged at the intersection points of a matrix array of row and column conductors includes a plurality of load resistors connecting the row conductors to a first voltage source and a plurality of load resistors connecting the column conductors to a second voltage source. To energize a selected lamp, the row conductor connected to that lamp is connected to the second voltage source and the column connected to that lamp is connected to the first voltage source.

Abstract: A touch sensitive control panel is disclosed which is constructed of a support surface and a graphic display member secured thereto. The support surface has regions of conductive material deposited thereon and the graphic display member has functional indicia printed thereon, there being a layer of adhesive intermediate the graphic display member and the support surface to secure the graphic display member to the support surface with the functional indicia in registration with the conductive material regions. The graphic display member and the adhesive layer form a dielectric medium between the conductive material and a body portion of an operator touching the front surface of the graphic display member. An improved method for manufacturing such a touch panel is also disclosed.

Abstract: An arrangement for obtaining pattern feed elongation in an electronically controlled sewing machine by utilizing a potentiometer for feed length variation, which potentiometer at a certain point switches in a feed multiplication and reduces its effectiveness so as to obtain a uniform change in feed from 0 to the maximum multiplication desired. Two embodiments are disclosed, one of which utilizes a comparator to eliminate a switch.

Abstract: For a zigzag sewing machine having a buttonhole presser device allowing formation of a buttonhole in a single step, a method for insuring that the presser device is in its initiating position by determining where the movable portion of the presser device is and, if it is not in its correct position, to adjust feeding action required to move it to its correct position.

Abstract: An optical buttonhole switching arrangement in which the movement of reflective means carried on a moveable buttonhole foot are sensed as the foot is moved by the fabric feeding movement of a feed dog against the garment being sewn. The foot includes adjustable optical targets whose movement may be sensed by a photosensor carried on the sewing head. The spacing of the optical targets may be manually adjusted to accommodate buttons of different sizes. The photosensor is connected to an electronic circuit whose output may be used to control the retrieval of buttonhole stitching information from an electronic memory.

Abstract: A method and apparatus for controlling refrigerant gas pressure in a low pressure refrigeration system including a warm surface within a container. Liquid refrigerant is removed from the refrigeration system evaporator and sprayed on the warm surface, thereby vaporizing. The resulting pressure differential between the container and the evaporator causes the vaporized refrigerant to be returned to the evaporator through an open return line. The warm, surface is downwardly concave so that non-volatile liquid which had been mixed with the refrigerant can be collected from the bottom of the surface and transported to a location remote from the evaporator, thereby separating contaminants from refrigerant.