Abstract: A thermostat device having a temperature responsive bimetal which permits movement of a permanent magnet between two fixed points to activate a reed switch element. The device includes a magnetic shunt for effecting a positive off position.

Abstract: The invention comprises a differential pressure switch including a housing which defines a cavity. A diaphragm with a pair of magnets mounted thereon is attached within the housing and vertically disposed across the cavity. This divides the cavity into a high pressure chamber and a low pressure chamber. A high pressure port and ducts in the housing place the medium to be detected in communication with the high pressure chamber. A low pressure port and ducts in the housing place the medium to be detected in communication with the low pressure chamber. The ducts also allow the chambers to drain. A reed switch is attached to the housing proximate the first magnet for maintaining the reed switch in an open state. A third magnet is positioned on the side of the diaphragm opposite the reed switch and in opposition to the second magnet for setting the switch. The third magnet may also be used to adjust the pressure differential required to actuate the reed switch.

Abstract: A variable differential switching apparatus comprising first structure for forming first and second magnetic fields presented sequentially along a travel path, the first field being stronger than the second field; and second structure, including a field responsive element, presented for relative travel along the path in opposite directions, the element and fields and travel path characterized in that as the element encounters the first field during relative travel in one of the directions in unlatched condition, the element is displaced by the first field into a latched condition, and as the element encounters the second field, it remains in the latched condition, and as the element continues to relatively travel in the first direction beyond the second field, it returns to unlatched condition; the element and fields further characterized in that as the element travels oppositely along the travel path, it remains in unlatched condition as the element encounters the second field, and thereafter as the element

Abstract: A plunger-operated switch assembly, useful for sensing the presence of a movable object such as a door or window, in which a magnetic reed contact is actuated by a magnet in the form of a disk-like roller plunger, or by a smaller magnet carried in the center of a roller plunger. The roller plunger is located in a cavity defined by a housing and projects through an aperture in a face plate including a flange by which the housing can be mounted recessed in a desired location. The magnetic reed contact is held alongside the cavity containing the roller plunger, so that the housing can be compact. A magnetic electrical conductor lead connected with a magnetic reed is located so as to be effectively within the magnetic field of the actuating magnet when the roller plunger is depressed a small distance so that the magnetic reed switch is actuated by a small movement of the plunger.

Abstract: Apparatus for proximity magnetic switching wherein magnet assemblies are used in combination with magnetic reed switches by placement of the reed switch axis in a magnetic field null position which is shifted or unbalanced by proximation of certain magnetic materials to actuate the magnetic reed switch. In particular, such proximity magnetic switch is made weather proof and entirely sealed from its environment by molding the magnet assembly and reed switch assembly in fixed orientation within a potted compound which then exposes an actuating surface for sensing the presence of a magnetically permeable material.

Abstract: The switch comprises a square, hollow housing. A base plate and a cover plate are snap fitted in stacked relationship. First and second elongated cavities in the base plate are respectively aligned with first and second cavities in the cover plate and within these aligned cavities are respectively located two elongated reed switches. A plunger is slidably carried by the housing and movable toward and away from the plates. The plunger carries two pairs of magnets respectively aligned with the reed switches. When the plunger is depressed, the magnets move into close proximity with the reed switches, closing them. A spring biases the plunger away from the reed switches, whereby the reed switches are normally open.

Abstract: A system for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An oscillator has an output coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a funciton of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. In the preferred embodiments of the invention disclosed, an automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit in a predetermined or preprogrammed manner during a calibration operation to a point indicative of the predetermined reference material level.

Abstract: In a method for the generation of control signals in a push button box and transmission of the signals for the control of a machine, signals representing the position of a push button element are transferred by a non-contacting mode from the push button element to a signal generating unit, which is adapted to produce control signals proportional to the position of the push button element. A push button box for carrying out the method comprises at least one push button element, a signal generating unit adapted to receive the signals representing the position of the push button element by non-contacting mode, and further adapted to generate control signals proportional to the position of each of the push button elements, and a partition between each push button element and the signal generating unit.

Abstract: A device for use as a float switch device for use in a liquid medium is disclosed which has a magnetic latching feature used to produce an offset, with the switch actuating in a first manner when the liquid level drops to a first level, and actuating in a second manner when the liquid level rises to a second level which is aabove the first level by a selected offset distance. The float element has two buoyant disks on the ends of a hollow cylinder, with switching magnets being located intermediate the two buoyant disks, and latch magnets being located on the bottom of the bottom buoyant disk. The float element slides vertically on a switch stem having a magnetic reed switch therein and a steel washer on the bottom thereof, with the float element being latched in a downward position by the latch magnets until the liquid level rises to the level of the upper buoyant disk, resulting in crisp and precise operation of the switching function.

Abstract: A magnetic switch assembly for an electrical circuit includes a switch housing with a cavity formed therein and at least one magnetically attractable electrical contact member exposed within the cavity. One or more electrically-conductive magnetic pole members are movably disposed within the cavity, with a magnet being secured to the pole members for movement therewith. The pole member or members and the magnet are movable in the cavity between a first position in electrical contact with the contact member in order to complete electrical continuity of the electrical circuit, and a second position spaced away from the contact member in order to break electrical continuity of the electrical circuit. A movable and magnetically attractable striker member is disposed for movement toward and away from the switch housing cavity, such as on a pivotal or hinged accessory cover.

Abstract: The invention as disclosed is a control mechanism adapted for actuation by a human, in the exemplary embodiment by a person's foot. The invention provides for control or actuation of a plurality of devices to be controlled. A plurality of control elements, preferably arranged arcuately with respect to an actuating member is provided with a structure for accurately indexing the actuating member to a particular control element by way of one mode of movement and for actuating an individual indexed control element of a second mode of movement. Particular structure is provided, by way of a foot pedal, in the exemplary embodiment, with particular adjustments so as to adapt the actuating member, that is, the foot pedal, to various sizes and positions of an operator's foot, as well as amplitude of actuating movement.

Abstract: A rotary electrical switch is provide for a portable power operated surface treating device having a fixed handle assembly, a hollow generally cylindrical roller supported for rotation on and relative to the handle assembly, and an absorbent generally cylindrical applicator sleeve coaxially supported on said roller for rotation therewith. The roller is driven by an electrical motor contained within it and powered by a rechargeable battery also supported within the roller. Operation of the motor is controlled by the rotary electrical switch which includes a pair of magnetically responsive electrical switch contacts contained within the roller and a magnetic switch actuator mounted on the handle assembly.

Abstract: A security system for use in a physical security monitoring environment includes a switch unit having a common conductor, a guard conductor and at least three switches. Each of the switches has a deactivated condition and an activated condition and each is adapted to be placed in its activated condition in response to a magnetic field of predetermined magnetic flux. The switch unit also includes a logic circuit electrically interconnecting the switches and the common and guard conductors, the logic circuit completing a series circuit between the common conductor and the guard conductor whenever at least two predetermined but not all switches are in magnetically actuated condition.

Abstract: A rotational position indicator useful for example for indicating wind direction is provided by a stator having nine position sensors substantially equally spaced around the circumference of a circle and an armature mounted for rotation on an axis located at the center of the circle. The armature is formed with two position sensor actuators mounted at approximately 140.degree. relative to each other. Each position sensor actuator is mounted at a radial position for selectively actuating the position sensors upon rotation of the armature. An electric circuit is coupled to each position sensor for indicating actuation or not of the respective position sensor. The output provides a unique position code for successive intervals of angular positioning of the armature relative to the stator. The actuators have an actuating effect over a selected angular interval sufficient to produce 36 unique position codes for indentifying successive 10.degree.

Abstract: Electronic switch comprising an operating means (1;7;12;15;18) movable in the switch. The operating means has only one magnetic pole operative for its motion, said pole being arranged to coact without contact with at least one second magnetic pole of a second magnet (5;5a) placed in the switch.

Abstract: A magnetic amplifier housing uses a base, dowel and shunt to magnetizable terial to concentrate the magnetic field of a ring magnet through a Hall Effect transistor to provide an improved detector device with increased gain. The detector device causes polarity reversal when tampered with, ensures positive mechanical alignment of the transistor and mechanical components, and protection of the transistor from mechanical damage.

Abstract: A power receptacle with alarm switch that is actuatable by a standard grounded three-prong plug to output a switch indication. The device consists of at least one three-prong receptacle wherein the third prong contact assures a common or ground connection upon insertion of a three-prong plug. A switch device is secured on the receptacle to extend an actuating arm adjacent the third prong hole in interfering position such that insertion and removal of the plug causes the third prong to move the actuating arm and produce a characteristic switch indication. An improved form of alarm switch uses a hermetically sealed magnetic switch in association with a spring-loaded plunger/magnet assembly to provide corrosion-proof switching.

Abstract: The improved magnetic proximity detector includes a tubular housing, a tubular magnet fixed in position within the housing, a first movable magnet within the housing at one end of the tubular magnet, a second movable magnet with the housing at the other end of the tubular magnet, an annular magnet positioned in surrounding relationship to the housing and being adjustable axially with respect to the housing, a switch having a blade, a first contact and a second contact, a connection extending between the first and second movable magnets and to the switch blade to move the switch blade responsive to movement of the magnets, the poles of the first movable magnet arranged so that the magnet is attracted to the tubular magnet, the poles of the second movable magnet arranged so that the magnet is repelled by the tubular magnet, the end of the housing containing the first movable magnet moving the two magnets responsive to ferrous metal in close spaced relationship to such end to change the position of the blade swi

Abstract: This invention pertains to a key operated mechanism for producing coded signal combinations for selecting a function of a multifunctional device. The mechanism includes a plurality of magnetically operated switches arranged along a key guide. The key includes magnets specifically positioned for interaction with the magnetically operated switches in accordance with a code diagram. Closing of the switches sends signals to a code signal user, which if the signals are enabling activates an associated machine such as a franking machine.

Abstract: The invention relates to an electrical system with at least one electric load unit (E) magnetically attached to a surface (F) being provided with path conductors (L). The load unit (E) comprises an electric load (G) being mounted on a socket (S). The socket (S) is provided with at least one magnet (M) and contacts (K) are arranged at the bottom side of the socket (S), through which contacts electrical energy supplied by a low-voltage source (SP) is fed to the load (G) via said path conductors (L). The contacts (K) are arranged such that the load (G) can be switched ON or OFF when the load unit (E) is displaced and/or turned. The load (G) may be as luminary.

Abstract: A liquid level sensing means for use in a tank or the like, adapted to hold a liquid which is partially withdrawn and/or replenished from time-to-time. Disposed within the liquid is a buoyant, upright, hollow reed switch-like float element having a longitudinal axis parallel with the direction of movement of the liquid level within the tank. The switch element is adapted to float upon the surface of the liquid whose level is to be sensed. It is provided with an upper reed and a lower reed, each in alignment with the longitudinal axis of the float element. The upper reed is rigidly secured to the upper end of an envelope of the float element, while the lower reed thereof is spring biasly secured to the lower end of the float element envelope. At a location medially between the upper and lower ends of the float element envelope, there exists an area of overlap between the unsecured ends of the upper and lower reeds respectively.

Abstract: A process instrument enclosed in a hermetically sealed housing for indicating and controlling a measured variable, such as the level in a tank. The instrument includes magnetically operated electrical switches actuable between open and closed positions in response to the measured variable. The electrical switches used are capable of switching current levels on the order of 10 Amps.

Abstract: Robbery alarm switch having two independently manually engageable plungers that must be substantially simultaneously moved by a cashiering accostee to actuate a summoning alarm. The robbery alarm switch includes at least one internally housed reedswitch connected in electrically intervening relationship to the summoning alarm. The two independently manually engageable plungers are respectively provideable with an addendum source of magnetic flux (e.g. a permanent magnet) so that, when the two plungers are together independently moved teamwise from normal first-station to second-station, the two magnetic flux sources act in concert to change the distance between the reeds of every electrically intervening reedswitch and thereby actuate the summoning alarm. Included among various optional features are: a supervisorily releasable housed latch extending between the two plungers; attaching the housed reedswitch to one of the two teamwise plungers; etc.

Abstract: A control mechanism comprising a casing, an operating lever (1) projecting at the top from the casing and arranged to swivel omnidirectionally against a spring-produced resetting force, and at least two transducers arranged according to two orthogonal axes for producing signals being a measure for the magnitude of the swivelling angle and for the swivelling direction of the operating lever (1).The operating lever (1) is mounted near its lower end in a ball joint (2) received in the upper wall of the casing, with the free lower end of the lever (1) abutting on four spring elements (3,6,9,12) whose lines of action (X,Y) coincide two by two intersect each other at right angles. The spring elements (3,6,9,12) are connected at the lower end of the operating lever (1) to downwardly extending oscillating or wagging plates (5,8,11,14) whose ends (A,B), upon swivelling movement of lever (1), are displaced inwardly in the direction of the axis of the casing.

Abstract: A robotic apparatus is provided with a separate ring of rubberized magnetic material with means for positioning the magnetic ring upon the piston which is of integral construction for actuating external signaling means.

Abstract: Apparatus for sensing the relative position between a fixed first machine component and an axially displaceable and pivotably mounted second machine component includes first and second bar-shaped magnets disposed at mutually right angles and rigidly connected to the second machine component, each of the magnets having a free pole; and a plurality of transducers rigidly connected to the first machine component and facing the free poles of the magnets for sensing the magnetic field of said magnets. At each long side of each of the first and second magnets an adjacent magnet disposed in parallel with the respective first or second magnet, each of these adjacent magnets having a free pole disposed in the vicinity of the free pole of the respective first or second magnet. The free poles of the first and the second magnets have a polarity reverse to that of the free poles of the adjacent magnets, and each magnet has opposite to its free pole a second pole directed away from the transducers.

Abstract: Fluid flow indicator is provided in which a fluid pressure to position transducer moves a permanent magnet from a no-flow position to a flow position in response to fluid pressure. The change in the position in the permanent magnet changes the intensity and polarity of the magnetic field that the permanent magnet places upon a Hall effect semiconductor; so that a switching function results as a function of fluid pressure differential causing no-flow and flow conditions. The change in magnitude and polarity of the magnetic field between first and second distances from one surface of the permanent magnet is increased by providing an opening through the permanent magnet and by providing a magnetic device near the opposite surface of the magnet.

Abstract: The present invention is directed to an apparatus and method for monitoring the continued rotation of a non-magnetically attractive indicator, e.g., a rotating, plastic dial, disc, wheel, arm or the like of a meter. The present invention is particularly useful for detecting the satisfactory operation of flow meters, e.g., meters used to determine the flow of fluids from oil and gas wells, in transmission lines and in chemical processing plants. The present invention provides a system for monitoring the operation or rotation by employing a rotating, magnetically attractive actuator to actuate a magnetic switch which in turn actuates an electrical switch for producing a monitoring signal. The apparatus and method of the present invention provide a rigid, dependable, accurate and wear-free device for monitoring the continued operation of a flow or other meter.

Abstract: To detect impending deropement of a wire haul rope from supporting sheaves in an aerial tramway system, there is provided a magnetic assembly having sufficient field strength to support itself in a predetermined position by reason of attraction to the wire haul rope when running normally in the sheaves. When the wire haul rope begins to run off one of the sheaves toward an impending deropement, the magnetic assembly will fall from its armed position to a substantially moved position. The magnetic assembly carries at least one position-responsive switch which interrupts a detection circuit when the magnet moves to the moved position. The interruption of the detection circuit is utilized to detect the location of the potential deropement and to terminate tramway operation.

Abstract: A housing assembly for a magnetically controlled element used to detect the angular position of a rotatable shaft includes at least one cavity for holding a corresponding number of insertable switch capsules, which capsules are preferably removable. The capsules are readily fitted in the cavities to precisely position a magnetic reed switch encapsulated therein into close proximity to a rotating shaft having a magnetic insert on at least one circumferential sector. The capsules also optionally include reed switch activated SCR circuits for generating an AC power output signal dependent upon the angular position of the rotatable shaft.

Abstract: A location detecting apparatus for use with a fluid conducting conduit in which a movable member moves includes an internally mounted magnet attached to the movable member and an external portion attached to the conduit for magnetically interacting with the internal magnet when the movable member is moved to a predetermined location. In the preferred embodiment there are two magnets, one extending from each end of the movable member. In this embodiment, the external portion includes two similar assemblies, each attached to a respective end of the conduit and each including suitable magnetically responsive switches, a reducing flange attached to the conduit, a manifold pipe extending through the reducing flange, and a clamping mechanism for releasably attaching the switches to the manifold pipe.

Abstract: A magnetically driven and latched actuator includes an armature, at least a part of which is of a ferromagnetic material, mounted for reciprocating travel between two spaced apart limit positions. An electrical coil is operative upon the ferromagnetic material to drive the armature alternately back and forth between the limit positions, and a pair of auxiliary ferromagnetic bodies are fixed, each adjacent to a respective one of the limit positions. The auxiliary bodies and the ferromagnetic portion of the armature are mutually magnetically attracted to each other so that the armature becomes magnetically latched at the limit position to which it is last driven by the coil.

Abstract: A remote manual shift control device having a manually operable range selector lever for controlling the operation of solenoids, relays and the like of an electrically controlled transmission, in which the selector lever is mechanically coupled to shift a code slide member to positions corresponding to the range positions, and wherein it coacts with switching components to generate binary coded output signals corresponding to the respective range positions as determined by the shift lever. The control device embodies a unitized sealed electronic module containing an IC Decoder Unit for the binary signals with inhibit and latch control terminals; and a connected Logic and Buffers Unit for determining the proper driving connections with the transmission control devices at the transmission.

Abstract: A liquid level control device for monitoring the level of water in a steam generating tank between predetermined upper, intermediate, and lower levels, with the tank equipped with a valve for introducing water into the tank and heat energy valve means to generate steam to the water, comprising: a glass gauge tube adapted to be vertically mounted exteriorally of the tank; a top and bottom cover covering the ends of the glass gauge tube, with a bottom cover including an opening for communicating with a liquid in the tank and the top cover including an opening for communicating with steam generated in the tank; upper and lower magnetic float means mounted co-axially within the glass gauge tubes; the upper magnetic float means including means to activate the valve when the water is the region of the predetermined intermediate level so as to introduce water into the tank until the water is in the region of the predetermined upper level, and to deactivate the valve and stop the introduction of water when the water

Abstract: A magnetic circuit device suitable for use in a magnetic catch having a switching function, a slide switch or a sensor for detecting locations of a movable member has been found. The magnetic circuit device comprises a main permanent magnet (1) having a pair of magnetic poles (N, S) on opposite faces, a pair of yoke pieces (2) lying on the faces, a movable piece (4) made of magnetic material capable of engaging with first ends of the yoke pieces (2), and a sub-permanent magnet (6) movably disposed near second ends of the yoke pieces (2) opposite to the first edges so that when the movable piece (4) is attracted to the first ends, the sub-permanent magnet (6) is attracted to the second ends, and when the movable piece (4) is made break away from the first ends, the sub-permanent magnet (6) breaks away from the second ends. Movement of the sub-magnet (6) can be utilized to control electrical connection of contacts (8A, 8B) of a switching mechanism.

Abstract: A hygienic device comprising an a.c. oscillating motor which has a fixed oscillation rate dependent on the a.c. supply frequency. The amplitude of the oscillations or torque of the motor is varied by varying the power supplied to the motor. The amplitude or torque may be varied in discrete steps by switching different resistors in series with the motor. Reed switches are used to switch the resistors and are mounted obliquely, to facilitate assembly and to reduce the danger of electric shocks to the user.

Abstract: An electrical connector system includes two cooperating connector components, each of which includes a housing of electrically insulating material and a support body mounted for movement within the housing. Each support body carries a contact member and a magnet member, and biasing means retracts the support body into the housing. When the two connector components are in juxtaposed relation, magnetic forces produced by the aligned magnet members interact to draw the support bodies out of their housings and place the contact members in engagement to complete electrical circuits therebetween, the circuits being maintained by the magnetic forces and released when the support members are moved to an offset position. The magnets provide a constant closing force on the contact members when the magnets are aligned, irrespective of the positions or relative movement of the closure surfaces that they are monitoring.

Abstract: A connecting and sensing device and a method for its use in a system for electrically monitoring physical security, including a magnetically operated switch, such as an encapsulated magnetic reed switch, and a quantity of ferromagnetic material located in a fixed position relative to the magnetically operated switch. The switch is connected electrically to an alarm system control circuit and is physically restrained by a flexible cable or the like. An actuating magnet may be attached either to an object whose unauthorized removal is to be detected, or to a fixed object. The actuating magnet is held within a holder including a cavity which permits the magnetically actuated switch and ferromagnetic material to be placed in a predetermined location wherein a magnetic field of a desired polarity and strength produces a desired condition in the magnetically operated switch.

Abstract: A gear shift position sensing arrangement for a gear selector unit that selects the transmission gears indirectly. Magnetic sensors are arranged in the gear selector unit housing so as to be activated when a permanent magnet associated with the gear shift lever is brought into magnetic proximity therewith.

Abstract: In response to a deceleration force, a rapidly reacting magnetic system causes a reed switch to change state. A predetermined time after the force ceases, a second, relatively slowly reacting magnetic system causes the switch to return to its original state. Each magnetic system includes a fixed magnet and a magnet movable within a recess. The reed switch is situated in a housing proximate the recesses and is controlled by the positions of the movable magnets. The recess through which the movable magnet of the slowly reacting system moves contains a fluid. This magnet carries a pair of self-positioning members which cooperate with the fluid to regulate the speed of the movement of the magnet within the recess, in accordance with its direction of movement, such that the slowly reacting system maintains the switch in the changed state and, thereafter, returns the switch to its original state.

Abstract: A thermal switch includes a reed switch surrounded by a centrally located, annular collar made of a ferrite material and a pair of annular permanent magnets spaced from the ends of the ferrite collar and positioned axially toward the ends of the reed switch. The magnetic spacing can be achieved by utilization of non-magnetic spacers, and the entire structure encapsulated to provide further durability, if desired.

Abstract: Float-controlled electrical switch (11) includes a reed contact (22) which is opened and closed by the field of force of a permanent magnet (32). The permanent magnet is embedded in a float which can be moved by rising and falling liquid levels towards and away from the reed contact for closing and opening of the reed contact. The reed contact (22) cooperates with a relay (25) which provides for engaging and disengaging of a working contact (18) for engagement and disengagement of a bilge pump (10) or another power device in connection with inspection of two separate liquid levels. Provision is made for a large distance between the liquid levels together with markedly distinct positions for engagement and disengagement of the reed contact by allowing the electromagnetic field of force of the coil (24) of the relay (25) to cooperate with the field of force of the permanent magnet.

Abstract: A magnetic switch has a fixed contact, a movable contact, and a flat, flexible blade supporting the movable contact, and movable between first and second positions in which the contacts are respectively engaged and disengaged. A blade magnet is affixed to the free end of the blade and is movable with it. An actuator is selectively movable to first and second positions corresponding to the first and second positions of the blade. An actuator magnet is positioned on the actuator in facing opposition to the blade magnet. When the actuator is moved to its first and second positions, one pole of the actuator magnet is disposed beyond the position of the blade magnet when the blade is in its respective first and second position. Thus, when the actuator is moved to one of its first and second positions, the blade magnet is repelled by the actuator magnet to drive the blade, with snap action, to the other of its first and second positions.

Abstract: A magnetic control device having a movable, permanent magnet or fixed-polar portion, a movable element of magnetizable material, i.e., material of high permeability and a plurality of fixed members also of magnetizable material.

Abstract: A manually actuatable direction controller includes a planar base supporting a number of magnetic reed switches, one of each direction in which control is to be exercised. The reed switches are arrayed about the plane of the base in a symmetrical pattern, with each one positioned in the direction over which it exercises control. A number of permanent magnets are arrayed in one-to-one relationship with the reed switches, with the magnets lying in a plane spaced from and parallel to the switch plane. A sheet of magnetically conductive material is supported for movement in the base between the plane of the switches and the plane of the magnets. An elongated handle has one end connected to the center of the sheet and projects normally from the base. The magnetic field imposed by each permanent magnet on its associated reed switch maintains that switch in a first state.

Abstract: The key switch comprises a housing with at least one permanent magnet accommodated therein, the magnet being rigidly connected with the key and adapted to act, when the key is displaced, onto a switching member secured in the housing. Mounted in the housing intermediate the key and the magnet are means for retaining the key in its initial position, including a plate of a ferromagnetic material. The housing further accommodates the means for returning the key into the initial position, including at least one plate of a ferromagnetic material, arranged in the direction of the motion of the key with a gap relative to the permanent magnet and defining with the plate of the key-retaining means a magnetic circuit. The length of this at least one plate of the means for returning the key in the direction of the motion of the key is short of the sum of the value of the maximum displacement of the key and the extent of the permanent magnet in this direction.

Abstract: The device senses the level of a float which may rest on the surface of the liquid whose level is to be determined or may rest on the surface of liquid (e.g., mercury) of a manometer which measures the level of liquid in accordance with the purge bubble principle. The fluctuation of the float turns a pulley which causes oscillatory movement of an arm carrying a magnet. In proximity to the path of the magnet is a board carrying radially disposed, angularly spaced reed switches. As the magnet passes each switch it closes same and passes a signal to a digital accumulator. A slip clutch between the arm and a second arm causes the latter to oscillate in the same direction as the first arm, but only for a limited distance. The second arm also carries a magnet which changes the direction of a second reed switch and dampens hunting of the first series of switches by preventing activation of the accumulator except when the second reed switch is closed.

Abstract: A vertical descent rate detector switch has a pair of contacts which are magnetically actuated when the rate of vertical descent of the switch exceeds a set amount.

Abstract: A method of and apparatus for changing the magnetic forces generated by and between a pair of magnetic assemblies spaced apart along a given path, by selectively positioning these fields with respect to each other.

Abstract: In a copier with a copying platen, and platen cover unit pivotal thereover, which may comprise a document feeder, the platen cover unit having connecting pivotal lifting means, and a magnetic latch for magnetically latching the platen cover unit in a closed position closely overlying the copier platen with a magnetic flux field between the platen cover unit and the copier generated by at least one magnet on one completing a magnetic circuit through at least one magnetic flux conductive member on the other when the magnetic latch is closed, the magnetic latching of the platen cover unit in the closed position providing for document retention and illumination thereunder and magnetic resistance to opening of the platen cover unit by the lifting means, and with a switch for indicating closure of the platen cover unit, the improvement wherein the switch comprises a magnetic switch magnetically coupled to the magnetic latch, the magnetic switch being magnetically actuated in response to the change in magnetic flux