Abstract: A control circuit comprising a thyristor and a feedback circuit formed by an inductance and a generator for producing electrical energy in response to a luminous event. The feedback circuit controls the conducting or cut-off state of the thyristor by the fact that a trigger-gate of the thyristor is connected to a terminal of the generator having a polarity cutting off the thyristor when the generator is illuminated. The thyristor is switched on in response to an energy stored in the inductance, which energy is caused by a sudden discontinuity of the luminous event.

Abstract: A detection device for measuring force and pressure is disclosed which includes a monomode optical fiber (1) into which polarized light is fed and, at the output of the fiber, is detected by a detection arrangement (4, 80, 81, 30, 40, 31, 41), which is sensitive to the polarization of the light. The detection arrangement is provided with means (30A, 31A) for analyzing the light according to at least two different polarization directions, forming an angle comprised between 30.degree. and 60.degree. between them. According to the invention, the device is provided with means (70, 71, 2) for feeding several non-correlated light signals, each polarized differently, into the input of the fiber, and with means (4) for distinguishing between the light signals in the said detection arrangement at the output of the fiber, which light signals have been fed into the input of the fiber. The invention is applied in intrusion detection, monitoring and security systems.

Abstract: A refrigerating machine (10) of the refrigerator or freezer type comprises a device (33) for defrosting cold parts to transform the ice into water to be discharged. It has an end-of-defrosting detector (20) comprising:(1) a reservoir (24) which receives the water to be discharged, one of the branches (23) of a siphon (21) extending into said reservoir in order to drain the reservoir when the water reaches the level required for activation of the siphon, the other branch (22) being situated externally of the reservoir,(2) a light barrier (27, 28), comprising a light source and a light receiver arranged around the other branch (22) of the siphon in such a way that the light beam of the light barrier is interrupted by the passage of water through said other branch while defrosting is in progress, and(3) a electric circuit (30, 31, 32, 34) which stops defrosting when the light beam is not interrupted for a predetermined time.

Abstract: A fiber-optical pressure sensor, comprising a pressure member (21, 22) which encloses the optical fiber (20) in a sandwich-like manner, and used for the detection of intruders is provided. The pressure sensor is formed by a continuous cable which can be buried and which comprises at least one optical fiber (20) which is capable of detecting, along its entire length, components of a pressure applied to a surface zone of the ground, notably by an intruder. The cable can be wound along an axis of rotation which is substantially perpendicular to its longitudinal direction and can be bent in a direction which is substantially parallel to this axis of rotation. The pressure member may have a continuous or a segmented structure. It may be formed by plates (21, 22) or strips (21, 22) which are rigid or semi-rigid. The pressure member may comprise ribs (27, 28, 29) which serve to capture forces which act in the lateral direction.

Abstract: A microwave oven which provides defrosting control for a frozen product to be defrosted. The oven comprises a microwave source and a detector arranged in the oven cavity in the proximity of the frozen product, the detector including a material which absorbs microwave energy, the absorption of microwave energy by the detector and by the frozen product causing their temperatures to rise and thereby defrosting such product. Variations in the detector temperature are measured by a measuring element which provides an electrical signal corresponding thereto. The detector is configured and insulated so as to have a heat exchange characteristic with its environment which results in its temperature detection sensitivity remaining constant during each of a plurality of successive defrosting operations of the oven. A computer control device evaluates when a defrosting operation has been completed by determining when the slope of the signal variation as a function of time remains the same at successive sampling instants.

Abstract: A microwave oven which includes a defrosting detector in the oven cavity in the proximity of a frozen product to be defrosted, the detector including a material which absorbs microwave energy, the absorption of microwave energy by the detector and by the product causing their temperatures to rise. Variations in the detector temperature are measured by a measuring element producing an electrical signal corresponding thereto, such signal being used to control the defrosting process. The microwave absorbent material is in the form of a layer deposited on a carrier which is positioned behind the product so that most of the detector area can only receive microwave energy through the product, whereby the rate of change of detector temperature with time decreases as the product defrosts and becomes constant when defrosting has been completed. The carrier may be one of the walls of the oven cavity or the oven tray. The material may be a resistive ink deposited on the oven tray by screen-process printing.

Abstract: A microwave oven includes a microwave source and a defrost detector arranged in the oven cavity in the proximity of a frozen product to be processed, the absorption of microwave energy being distributed between the detector and the product and causing their temperature to rise, the temperature variation of the detector being measured by a measuring element producing a corresponding electrical signal. The oven also includes a computing control device which determines completion of defrosting of the product by computing the values at successive instants of the second derivative of such signal as a function of time. The computing control device controls the oven at the end of the defrosting cycle, which is when the value of such second derivative falls below a predetermined value.

Abstract: A device for contolling the charging of rechargeable batteries comprises two temperature sensors deposited on a flexible thin thermally and electrically insulating sheet. The thin sheet is disposed around the rechargeable battery so that one of the sensors determines the temperature of the battery and the other sensor determines the ambient temperature. A charge stopping device stops the charging of the battery when the difference between the temperatures determined by the two sensors has reached a predetermined value. The sensors consist of resistors applied by silk screen printing and disposed in a Wheatstone bridge arrangement.

Abstract: An electric flat-iron safety device includes a magnet pivotally supported in a flat-iron and arranged to actuate a first magnetically operated switch only when the flat-iron is in a horizontal ironing position and to actuate a second magnetically operated switch only when the flat-iron as tilted to a vertical rest position. Should the flat-iron remain motionless in the horizontal ironing position for a first predetermined time interval shorter than the time necessary for the flat-iron to reach its normal operating temperature, closure of the first switch by the magnet causes a resettable dual interval timing circuit to interrupt the power supply to the flat-iron. If the flat-iron remains motionless in the vertical tilted rest position for a second predetermined time for a interval longer than the time necessary for the flat-iron to reach its normal operating temperature, closure of the second switch by the magnet causes the dual interval timing circuit to interrupt the power supply.

Abstract: A microwave oven with a door-closing safety device is provided wherein a movable door comprises a device wherein the beam of at least one light emitter is guided by means of light guides towards a light beam detector. The light guides are arranged along a substantial portion of at least one side of the oven door frame. The beam of light in its non-guided path between the emitter and the detector passes through diaphragms, integral with the oven door, each diaphragm having an aperture such that the light beam passes through it when the door is properly closed but wherein the light beam is intercepted by the edge of the diaphragm when the door is not properly closed. The detector activates a signal that actuates the magnetron when the light beam is received; however, when the beam is intercepted, activation of the magnetron is prevented thereby preventing leakage of microwave energy.

Abstract: An apparatus for detecting intruders comprising a housing provided with at least one window, a passive infrared detector (for detecting the radiation emitted by an intruder around a wavelength .lambda..sub.1), and an anti-obscuring device (detecting by infrared radiation having a wavelength .lambda..sub.2 the presence of an obscuring of the appparatus for detecting intruders). The apparatus further includes an electronic circuit intended to operate an alarm when the presence of an intruder or an obscuring element has been detected. The apparatus for detecting intruders has a detector for detecting an obscuring element arranged at small and at large distances. It further includes a self-verification circuit. An obscuring element is detected, inter alia, by a mirror arranged at the end of the zone to be supervised, which returns radiation .lambda..sub.2 emitted by an emitter to a detector, both being situated very close to the detector of radiation having a wavelength .lambda..sub.1.

Abstract: The invention relates to a microwave oven comprising control means which reduce the risk of no-load operation and which co-operate with an actuating element which switches on the magnetron with the aid of power-supply means depending on open and closed states of the oven door. The invention is characterized in that the control means comprise a bistable electromechanical device which responds to closures of the door by counting the number of these closures and which enables the magnetron to be energized after an even number of closures of the door, one cycle of operation of the bistable electromechanical device comprising two open states and two closed states of the door. The bistable device may comprise a lever device which actuates a pendant-type electrical switch or a remote-controlled switch.

Abstract: A method of renewing a used liquid for reuse of the same includes establishing a body of a reference liquid for comparison with renewed used liquid, and establishing a separate body of the used liquid adjacent the body of reference liquid. An incident light beam is produced for consecutive traversal of the body of used liquid and the body of reference liquid, the particles in the two liquid bodies thereby diffusing the light beam to provide respective luminous fluxes off the axis of the incident light beam. The two luminous light fluxes are separately detected and compared. This procedure is automatically terminated when the detected luminous light fluxes are substantially equal to each other.

Abstract: A door-open alarm device comprises alarm means connected to an electric circuit which comprises, arranged on the stationary part (11), a voltage source, a switch (13) having two positions in which the circuit is interrupted and closed respectively, electrical time delay means responsive to a current flow in the circuit to produce a voltage variation across said alarm means after a time delay, thereby triggering said alarm means. Arranged on the door (12) is a mechanical actuating element (14) for said switch, which opens said switch when the door is wide open or closed, and which closes said switch when the door is ajar.

Abstract: A method of detecting the release of dye from laundry in a washing machine despite the presence of dirt in the washing water. During a washing operation, a radiation flux including an infrared flux part (.phi..sub.I) and a visible flux part (.phi..sub.V) is passed through the wash water in which it is subject to absorption and diffusion. The flux parts .phi..sub.I and .phi..sub.V are compared during the entire washing program and the ratio of .phi..sub.V and .phi..sub.I is determined. The release of dye is signalled by a substantial variation of said ratio. The signal may be used for actuating an alarm device and/or controlling the washing program.

Abstract: A method of determining the average nature of the materials of a laundry in a laundry washing machine including measuring the weight of the laundry loaded into the machine, detecting the volume and the level of water admitted to the tub of the machine, determining the volume of water absorbed per unit of weight of the laundry and from these factors determining the nature of the materials in the laundry for a determination of the specific treatment and washing operation for such materials. A laundry washing machine with sensors and circuitry to carry out the method is also disclosed.