Abstract: In a method and apparatus for measuring the depth of a flowing fluid, and controlling the flow rate of the fluid based upon the depth measurement, the fluid is caused to flow through a conduit, where it is irradiated with a known intensity of light, and the fluid is caused to fall from a horizontally directed exit terminus into a reservoir having a reflective bottom. The fluid serves as a wave guide for the light it received within the conduit, and releases the light within the reservoir. The intensity of light reflected from the bottom of the reservoir and emergent from the fluid is directly proportional to the depth of the fluid in the reservoir, and is measured by a photodetector which transmits a control signal to a valve in the conduit.

Abstract: A non-invasive photoelectronic device which determines the location of a liquid column within a transparent tube. The device includes a source of visible light, transmitted as a substantially parallel light beam against a transparent lensing tube which may be a sightglass or a leg of a U-tube manometer located within the light beam. The liquid contained within the tube forms an identifiable liquid column which acts as a highly effective condensing lens to the transmitted light beams with a resultant focus close to the tube. A plurality of optoelectronic detectors are arranged in an array over the portion of the tube to be monitored. Each detector is a phototransistor which is responsive to the large change in light intensity caused by the lensing effect of the liquid-filled tube compared to the non-lensing action of the adjacent portion of the tube.

Abstract: An optical sensor is made of light transmissive material and has luminescent particles distributed throughout its volume. The luminescent particles are excited by a suitable type of energy, preferably light. As they return to their original state, they emit light uniformly in all directions. Depending upon the relationship of the index of refraction of the sensor body material to that of a test medium abutting a boundary surface of the sensor body, part of the luminescent light is reflected, the remainder passing into the test medium with a change in direction (refraction). When the test medium is optically less dense than the sensor medium luminescent light incident on the boundary surface at an angle exceeding the critical angle undergoes total reflection. For an elongated sensor body, this totally reflected part is transmitted to the end faces of the sensor, where its intensity constitutes a desired measure of a physical quantity.

Abstract: A liquid level indicator comprising a liquid storing tank for storing liquid therein containing a first transparent portion and a second transparent portion; a mounting member of the liquid storing tank therein containing a third transparent portion and a fourth transparent portion; a non-transparent cover of the liquid storing tank within the mounting member; and a lamp for emitting light into the liquid tank through the fourth transparent portion of the mounting member and the second transparent portion of the liquid storing tank, the light being reflected at the surface of the liquid level to pass through the first transparent portion of the liquid storing tank and the third transparent portion of the mounting member whereby the level of the liquid can be noted from outside the liquid storing tank.

Abstract: A fluid level and condition detector system including a multimode optical waveguide for insertion into a medium including at least a first fluid whose level is to be monitored, a source of radiation for introducing into one end of the waveguide radiation in a plurality of modes, and means for detecting the difference in radiation flux transmitted by the waveguide with the waveguide covered by the first fluid over its equilibration length, with the waveguide covered by a second fluid of lower index of refraction over its equilibration length, and with the waveguide covered partially by each fluid over its equilibration length and for detecting the difference in radiation flux transmitted by the waveguide due to the combined effects of the change in index of refraction and change in optical absorption coefficient of the first fluid covering at least a portion of the waveguide.

Abstract: A mini-regulator valve assembly for providing a continuous supply of fluid at a predetermined pressure from a source of high pressure fluid. The valve has a first member adapted to join with the fluid source and a second member disposed for movement relative to the first member, one of the members forming a valve seal and the other forming a sealing edge cooperating therewith. The valve is further provided with a first biasing spring, a second biasing spring and an actuator. The first biasing spring biasing the second valve member against the first valve member and the second biasing spring acting on the actuator such that when the second biasing spring moved inward, the actuator acts on the second valve member moving the valve seat and edge away from each other thereby opening the valve, the first spring in combination with the pressure of the fluid passing through the valve ending close to the valve as the pressure builds up and thereby obtaining a regulating affect.

Abstract: A local display of a fluid level is provided in connection with a fiber optic illuminating system in which a side by side, bi-color light is passed through the fluid in a level gauge having transparent viewing ports. Diverging light passing from the level gauge, refracted in response to the fluid and gauge material, is masked and one color is passed to a focusing lens and a local readout in a plane above or below the focusing lens.

Abstract: A liquid level gauge including an elongate support member, and, a plurality of optical fibres carried by the support member, said fibres extending on the support member generally lengthwise thereof and generally parallel to each other, said fibres being spaced apart from each other circumferentially of the support member and each fibre being divided at a point along the length of the support member by a gap so arranged that the transmission of the light across the gap from one part of a fibre to the other part thereof is determined by the presence or absence in the gap of the liquid being gauged, the gaps of the fibres being spaced lengthwise of the support member.

Abstract: A method for detecting small leaks in a tank storing a liquid by measuring changes in the location of a float suspended in the liquid. The method includes the steps of sealing the float to prevent the condensation of vapors within the float, positioning the float at a preselected depth, modulating an emitted signal by an amount which varies with the changes in the location of the float, and detecting the modulated signal. Changes in the signal are indicative of small changes in the location of the float and small leaks in the tank.

Abstract: An apparatus such as a humidifier comprises a water storage tank having an externally exposed surface made of a transparent material and its bottom surface is made partially or totally of a transparent plate. A light source is disposed underneath this transparent plate and there is placed inside the tank a structure having surfaces for reflecting or refracting light from this source to the aforementioned externally exposed surface so that the water level inside the tank is easily visible.

Abstract: A sensor element for a liquid level sensor of the "light prism" type is constructed so as to have a gradually tapering frusto-conical shape and a sensing surface at its lower tip. Such a shape has a tendency to collomate the light transmitted within it and to concentrate all critical reflections in the lower tip of the sensor element, thereby defining a relatively concentrated sensing area. At the same time, the sensor element is shaped and dimensioned in the vicinity of the sensing surface so that the surface tension of the droplet causes the droplet to be lifted upwardly and away from the sensing surface. Any deliterious effect of the droplet on the sensing ability of the sensor is thereby avoided.

Abstract: A humidifier (10) used in respiratory therapy is disclosed where the surface tension of a light probe (32) used therewith is maintained greater than the surface tension of the aqueous liquid used in the humidifier (10). Maintaining the surface tension of the light probe (32) greater than the surface tension of the aqueous liquid generally avoids erroneous indication of aqueous liquid level in the humidifier (10). Erroneous indications of liquid level can be caused by gas bubbles adhering to submerged portions of the light probe (32) or liquid droplets adhering to unsubmerged portions of the light probe (32).

Abstract: A method for detecting small leaks in a tank storing a liquid by measuring changes in the location of a float suspended in the liquid. The method includes the steps of sealing the float to prevent the condensation of vapors within the float, modulating an emitted signal by an amount which varies with the changes in the location of the float, and detecting the modulated signal. Changes in the signal are indicative of small changes in the location of the float and small leaks in the tank.

Abstract: An ink-jet recording apparatus having a detecting means for detecting ink pressure or an ink-residual quantity in the ink supply. The detecting means has a light shielding means coupled to the flexible diaphragm of the ink supply so as to be movable responsive to deformation of the flexible diaphragm. An ink pressure variation of -5 to -10 cm H.sub.2 O results in a diaphragm displacement of 5 um/cm H.sub.2 O to 20 mm/cm H.sub.2 O.

Abstract: A liquid drainage system comprising, a container having a cavity to receive the liquid. The system has an associated light emitter and light detector being changeable between a first state with the light from the emitter impinging upon the detector, and a second state with the light from the emitter passing away from the detector dependent upon the presence of liquid in the container between the emitter and detector. The system has a device for moving the emitter and detector vertically along the container.

Abstract: A probe is fixed to a vertically displaceable rack. Under the probe is a reference plate freely exposed to snowfall. The probe is periodically lowered toward the reference plate and stopped when it encounters either the plate or a layer of snow which has fallen on the plate. With the aid of a light barrier and a perforated disk, electrical signals dependent upon the distance travelled by the probe are generated and transmitted to an evaluating device. This device calculates, on the basis of the signals received, the difference between the aforementioned distance travelled and the distance from the reference plate to the probe in its uppermost position. This difference corresponds to the thickness of the deposit of snow on the plate. For subsequent measurements, a new reference value corresponding to the surface of the snow already lying on the plate can be used for the calculation. Hence there is no need for clearing the plate of snow after each alarm signal.

Abstract: A level sensing system including ultrasonic sound wave transducer means for emitting ultrasonic sound waves and for receiving ultrasonic sound waves reflected from a receptacle whose content level is to be sensed; a content level detector, responsive to the reflected ultrasonic sound waves, for determining the level of the contents of the receptacle; a rim detector, responsive to the reflected ultrasonic sound waves, for determining the location of the rim of the receptacle; and a level comparator, responsive to the rim detector and the content level detector, for comparing the content level with the rim location for indicating when the content level and the rim location are a predetermined distance apart.

Abstract: A level indicator for a portable toilet comprises a visible indicator on the exterior of the toilet's holding tank, a float mechanism on the tank's interior operable to sense the level of liquid material in the tank, and a magnetic coupling between the float mechanism and the indicator for causing the indicator to be operated to a position corresponding to the level of liquid material sensed by the float mechanism. The indicator is in the form of a wheel journaled on a receptacle in the top wall of the holding tank. A magnet mounts on the wheel in radially spaced relation to its axis. The float mechanism comprises an arm which is operated along an arc in response to changes in the level of liquid material in the tank. The arm has a magnet which swings in a corresponding arc and which confronts the wheel magnet so that the wheel is rotated about its axis as the float arm is operated about its own axis.

Abstract: A sensing system and method for detecting changes in the level of a liquid surface utilizing a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward a liquid surface at an oblique angle thereto, and thereby providing a reflected beam therefrom. A beam expander is interposed between the illumination source and the liquid source for increasing the narrow beam width of the incident beam to a beam width substantially greater than the wavelength of disturbances in the liquid surface. A converging lens is mounted transverse to and intercepts a portion of the reflected beam from the liquid surface for focusing that portion of the reflected beam to a centrum. A beam detector is positioned adjacent to the centrum for providing an indication of changes in the level of the liquid surface by detecting corresponding changes in a relative position of the centrum.

Abstract: Containers pass through a radiation beam projected from a beam source to a detector. The detector output pulse rates at points where the container has passed partially into the beam and partially out of the beam are detected. Pulse rates during a measuring interval which lies between these points are divided by time units from a clock pulse generator to produce a signal representative of the average pulse rate during the interval. This signal is compared to a selectable reference signal. If a comparison is made, the comparator yields a signal indicative of whether or not material in the container was at a high enough level to attenuate the beam.

Abstract: A liquid level detecting device, which has a low transmission loss and may be miniaturized, comprising a plurality of optical fibers each composed of a core made of a transparent material and a cladding layer covering the core therewith and made of another transparent material having a lower refractive index than that of the former transparent material forming the core, end portions of the optical fibers being placed in adjacent to each other in either parallel arrangement or that attained by making an acute angle with each other, and a detecting portion which is obtained by heating the adjacent end portions of these optical fibers to fuse one another and shaping into a spherical form due to the surface tension of the fused material.

Abstract: An apparatus for detecting small changes in the location of a float, has, in combination, a signal generator for emitting a signal having a characteristic, a detector for detecting a modulated signal by producing a response signal directly related to the characteristic, a support for positioning the signal generator and the detector, and a float weighted to float at a desired depth in a selected liquid. Also included are a reservoir for holding a measuring medium, a plug for preventing condensation of vapors within the float, with the float movably connectable to the support, and the detector and the signal generator fixedly connectable to the support so that the signal when emitted by the signal generator will have the characteristic of the signal modulated by the measuring medium by an amount which varies with changes in location of the float to produce a modulated signal.

Abstract: Apparatus is disclosed for determining the position of a surface in which radiation from an optical radiant source is applied to the surface and, by means of a lens system, an image of the radiation is produced on a photoelectric receiver. A laser serves as the radiant source, and is aimed at an angle of inclination relative to an optical axis of the lens system at a point of a surface which, by virtue of its temperature, emits visible radiation in the same wavelength range as the Laser. The surface extends approximately perpendicularly of the optical axis and is subject to positional variations along the said optical axis. The beam is directed from the irradiated point to the photoelectric receiver through a narrow-band optical filter of which the pass band includes the laser wavelength.

Abstract: A water level gauge with fault detector comprises a column for containing a level of water with a plurality of light sources on one side of the column and a plurality of detector assemblies on an opposite side of the column. Filters are utilized to project red and green light through the column. Each detector assembly includes a red detector and a green detector with red and green filters respectively. Due to the difference in offset of light beams transversing the column at an oblique angle through water and through air, the green detector is activated by green light when the green and red light passes through the water in the column and the red detector is activated when the light passes through air in the column, that is, above the water level in the column. By a circuit connected to each detector assembly, it is possible to discover the level of water in the column.

Abstract: A generated signal is passed through an elongated signal conveying element positioned preferably perpendicular to the surface of a fluid the level of which is to be measured. The signal is directed from the signal conveying element to a detector element which senses the signal output from the signal conveying element. The signal output detected in an optical embodiment varies logarithmically with the depth of immersion of the signal conveying element into the fluid. A preferred embodiment employs an electromagnetic wave, e.g., light, signal which passes through a light pipe signal conveying element. By nearly matching the light pipe index of refraction with that of the fluid, a predetermined precentage of the wave is lost into the fluid each time the light is reflected further along the pipe.

Abstract: An oil-level detector is mounted on the outside face of a glass window in the wall of an oil tank. The detector has two fibre-optic cables which extend within a cavity between the detector and the window. The ends of the cables are mounted one above the other, one cable transmitting a beam of light at an angle .alpha. of 60.degree. to the window, through an oil in the cavity which has a refractive index substantially equal to that of the window glass. The angle .alpha. is greater than the critical angle of glass with air, and less than the critical angle of glass with the oil in the tank. When the window is covered by oil in the tank the light is refracted into the tank. When the oil level falls below the window, the light is reflected to the other cable which is connected to a control unit. The control unit gives a warning a predetermined time after the level has fallen.

Abstract: A liquid level sensing device, particularly useful for apparatus designed to humidify oxygen gas being administered to patients undergoing respiratory therapy is disclosed. The liquid level sensing device detects the liquid level in a canister having an optical probe therein. A bracket, rotatable on a frame of the device, carries a light source and a light sensing member for determining liquid level in the canister in conjunction with the probe. The hinged bracket engaging relation, and it also rotates out of probe-engaging relation and registry with the light probe. When the bracket is out of registry with the light probe, the canister may be removed and replaced. The bracket may be releasably retained out of probe-engaging relation by means of a snap fit structure.

Abstract: A liquid level indicator which includes a plurality of pairs of optical fibers and a common carrier supporting at least an end portion of each fiber. The carrier is formed with an elongated passage into which, in use, liquid flows to a height dependent on the liquid level to be monitored. The end portions of each pair of fibers are separated by the passage and have their axes generally coextensive, while the end portions of adjacent pairs of fibers are spaced apart along the passage. The end surfaces of end portions of each pair of fibers are inclined at an acute angle to the axis of the fibers such that transmission of light from one fiber to the other is substantially prevented if the liquid does not fill the region of the passage between the fibers, while light is transmitted between the fibers if the region of the passage is filled with the liquid.

Abstract: A method of measuring the bath level in a cool tubular mould utilized in a continuous casting process where a melt of metal to be cast is discharged from a container therefor into the mould via an immersion tube vertically extending into a bore through the mould to thereby establish the bath, there being an annular space between the immersion tube and the wall of the bore, and where the melt is soldified by the cooled mould and continuously withdrawn therefrom as a solidified bar.

Abstract: A sensor syringe or hollow needle arrangement for the automatic withdrawal of a liquid sample from a liquid contained within a vessel. A duct is enclosed in a sheath or jacket-like manner by a light conductor possessing an inlet for an optical source and an outlet leading to an optical detector. During sample withdrawal there is utilized the change in the reflection behavior of the lower end of the light conductor upon its immersion in the liquid in order to control sample withdrawal.

Abstract: An apparatus for monitoring and indicating the amount of material at a given level in a plurality of hoppers or bins includes a detector for sensing and indicating the build-up of the material on the side walls of the hoppers. A sensor positioned at each hopper senses the amount of material at the given level and generates a pulsed output signal which is accumulated over a predetermined time interval to represent the amount of the material at the given level in the hopper. The value of the accumulated output signal is compared with the values of first and second reference signals to generate "full" and "not full" indications respectively. Typically, the indications are a continuous "not full" light when the hopper is empty, a flashing "not full" light as the hopper is filled, a continuous "full" light when the hopper is full, and a flashing "full" light as the hopper is emptied.

Abstract: A water level indicating apparatus (10) has an optical system (22) for establishing an optical signal indicative of water level which signal is split by a beam splitter (18) to transmit the majority of the optical signal to a fiber optic cable (16) and to reflect a part of the signal to a proximately located (13) glass diffuser (14). The end 24 of the cable (16) is reflected in the beam splitter (18) to form a reflection (24') which varies in intensity as the end (24) of the cable (16) is moved with the brightest reflection (24') appearing when the lamp(26) of the optical system (22) is in line with the end (24) of the cable (16).

Abstract: An apparatus useful in detecting changes in distance comprises: a signal emitter capable of emitting a substantially constant signal; a signal reflector capable of reflecting at least a portion of the substantially constant signal and being moveable in a substantially straight line direction toward or away from the emitter; and a signal receiver capable of receiving the reflected signal, whereby a change in the received signal is indicative of a change in the distance between the emitter and reflector. This apparatus is particularly useful in detecting changes in the amount of liquid in a liquid storage tank.

Abstract: An apparatus for monitoring the level of material in a plurality of hoppers or bins includes a radiation source and sensor associated with each hopper. Each sensor generates an output signal representing the incidence of radiation passing through the material in the respective hopper. The sensor output signals are supplied to individual sample/hold circuits where they are temporarily stored. A central control circuit cyclically reads the stored signals from the sample/hold circuits and then generates a reset signal to clear the sample/hold circuits. The central control circuit compares the sum of the sensor output signals for each sensor over a predetermined time interval with at least one reference signal representing a predetermined material amount to generate a status signal for each hopper. A plurality of indicator circuits are responsive to respective condition of the status signals for visually and/or audibly indicating to an operator the status of the material level in the associated hopper.

Abstract: A water level indicating apparatus (10) has an optical system (22) for establishing an optical signal indicative of water level which signal is split by a beam splitter (18) to transmit the majority of the optical signal to a fibre optic cable (16) and to reflect a part of the signal to a proximately located (13) glass diffuser (14). The cable (16) extends to a matte screen (12) at a remote location (11) to thus provide a remote (11) optical signal as well as local (13) optical signal indication of the water level.

Abstract: The liquid level indicator contains a number of first light fibers, a number of second light fibers, optical lens means interposed between each output end of the first fibers and an associated input end of the second fibers, and light detectors associated with the output ends of the second fibers. The optical lens means has substantially the same index of refraction as the liquid. When the lens means is not immersed into the liquid, it focusses light from the first fiber to the second fiber. This focussing effect is eliminated when the lens is submerged into the liquid.

Abstract: Improvements are disclosed in liquid level sensing apparatus having a liquid replenishment line so that as liquid is expended more may be added to keep the liquid at a desired predetermined level. The apparatus is contemplated for use in the humidification of gases, particularly for the administration of oxygen and the like to a patient.

Abstract: In order to sense a liquid level, an input light pipe and output light pipe have angled ends such that light supplied to the input light pipe is directed from it to the output light pipe by total internal reflection as long as the ends are in a gas. When in a liquid, the index is such as to cause light in the input light pipe to refract into the liquid and not reach the output light pipe. By observing the other end of the output light pipe it becomes possible to determine if the angled ends are in liquid or gas, and thus detect a liquid level.

Abstract: A low liquid level electro-optical probe is made self-checking by providing the same with means for intercepting a portion of the usual light beam and constantly reflecting such portion to the usual receiving electro-optical transducer to constantly generate a low level electrical signal even when the probe is wet. Means are provided for boosting the signal to activate an alarm, failure of which will be indicative of failure or malfunctioning of one or more elements of the system.

Abstract: The invention relates to a fiber optical measuring device for measuring physical parameters of a medium, preferably the level thereof, and it comprises an electronic unit and a transducer unit interconnected by an optical fiber, the transducer including at least one light guide connected to the optical fiber. The light guide is adapted to be lowered or introduced into the medium, the level, or other parameters, of which is to be measured, the light guide having a core with a higher refractive index than the surrounding sheath. The sheath has one or more regions along the light guide that are light transparent by being uncovered or only very thinly covered. When the guide is immersed into the medium, it influences the channel such that light in the thinly covered or uncovered regions of the guide is transmitted from the core, which light is representative of the level, or other parameter, of the medium.

Abstract: An apparatus for measuring the volume rate of flow of flowing fluids by means of a flow meter, called rotameter, in which a linear light source and a plurality of light sensing means are engaged along diametrically opposing generatrices of the transparent measuring tube of the rotameter, and the float in the measuring tube intercepts the light path so that the state of illumination of the light sensing means corresponds to the position of the float in the rotameter tube, and the outputs of the light sensing means are combined in a logical circuit to produce a signal combination representing said float position.

Abstract: An improved brake fluid reservoir is disclosed. The reservoir is made from polymethylpentene and includes 10-20% by weight glass fibers as an opacifying agent. A translucent reservoir is obtained which has the highly desirable feature of visibility of the fluid level in the reservoir without providing a clear view of the fluid.

Abstract: An electronic dipstick or similar probe has an electrically insulated conductor which is diminished or otherwise adjusted with respect to a given point of reference and a predetermined low liquid level. Level monitoring functions on liquids having high volume resistivities in the megohm-centimeter range are attainable.

Abstract: A liquid level sensing means for providing a continuous indication of liquid level or liquid content of a container comprising an elongated light conducting element adapted for being received into a liquid having first and second ends and a surface which provides an interface with the liquid for measuring liquid levels between the ends of the conducting element. A source provides radiation to the conducting element at one end, and detecting means for sensing radiation transmitted by the conducting element is positioned at the end of the conducting element opposite to the source of radiation and provides an output signal responsive to the intensity of the sensed radiation. The conducting element is transparent to radiation, has an index of refraction which is greater than that of the liquid which is to have its level measured, and has contoured regions on at least a portion of its surface.

Abstract: A single optical sensor coupled to an oil return line in an internal combustion engine is coupled to a control circuit for determining during a first time interval when the engine is started whether the crankcase oil level is sufficient and during a second time interval after the engine is running whether the oil needs to be changed.

Abstract: A humidifier for gases, for example for medical administration, may be adapted for insertion into a well of a heater for warming liquid in the humidifier. A seamless metal can defines a cylindrical wall and a closed bottom end, containing wick means for absorbing water and presenting it in dispersed form to gases flowing through the can. Transparent probe means extend into the can and serve as a liquid level control for preferably automatically controlling the liquid level in the can to be maintained in the lower one third of the can.

Abstract: A U-shaped device wherein the presence or absence of a transparent liquid or solid between the legs of the U is sensed. The device utilizes a collimated light source mounted in one leg of the U with an associated limited field of view sensor in the other leg of the U-shaped device. The light source is placed so as to cause the transmitted light beam to strike the surface of the material to be sensed at an angle which is substantially off of a line perpendicular to the surface of the sensed material.The light sensor is placed so as to receive the light beam when there is no liquid or solid material present between the source and the sensor and to prevent the refractively bent light beam from striking the sensor when a transparent liquid or solid is placed between the light source and sensor.

Abstract: A device for determining the relative properties of stratified fluids, such as the interface between oil and water having plural fluid character recording stations with sensors on an elongated member. Means are provided to clear the recording stations to preclude contamination of the sensors by fluid from other strata.

Abstract: An apparatus for detecting the level of a liquid in a container by modulating the intensity of light propagating through a fiber-optic light guide, a section of which has the cladding removed or partially removed. The system consists of a light source which is coupled into the input end of a fiber, a section of fiber from which the cladding is removed, a liquid-containing vessel into which the unclad fiber section can become immersed, and a detector at the output end of the fiber.

Abstract: An optical fluid level monitor is disclosed. It comprises a plurality of prismatic sensors disposed in a linear array for measuring the levels of fluids, such as oil, in sumps of aircraft and helicopter engines and other closed containers. In use each of the sensors is sequentially pulsed by an integral light source. If the detector is above the fluid level it appears bright, if below it appears bright, if below it appears dark, this difference being caused by an integral light detector device. Counting circuits are provided to determine the number of bright sensors and electronically convert this into a fluid volume for display purposes. A presettable low volume alarm is also included as is a correction circuit to compensate for volume changes caused by heating of the fluid in use.