Abstract: The device for the detection of a wetting of a pane of glass, has an optical rain sensor which detects extraneous light and evaluates it for purposes of day-night detection. The amount of light striking the receiver (14) is integrated in an integration stage (16) and supplied to a comparator stage (20). The total light quantity formed by the light of a transmitter (12) and extraneous light and the extraneous light quantity detected when the transmitter (12) is switched off are measured in separate time intervals (Tg, Tf, Tf′). The time interval (Tf, Tf′) utilized for measurement of the extraneous light quantity is to be extended after a predeterminable number of measurement cycles (M) or after a predeterminable time period and/or the threshold (S2) is to be lowered for day-night detection.

Abstract: An in-line sensor apparatus and method for the control of fluid manufacture, especially the manufacture of carbonated beverages, provides precise and reliable monitoring of several characteristics of the material of interest. The apparatus consists of a sensor head that is mounted at a point in the process where control is needed. A controlled wavelength light is directed toward the fluid being monitored. The light is sensed directly and after passing through the fluid. Sensor data is processed into reference and quality signals. Fluid quality is predicted by processing these signals.

Abstract: The invention is a precipitation sensor adapted to detect water upon an automotive glass and a method for its use. The precipitation sensor includes an optical emitter and a first mirror surface in optical communication with the optical emitter. The first mirror surface is adapted to reflect and collimate light emission from the optical emitter. The precipitation sensor also includes an optical receiver and a second mirror surface in optical communication with the optical receiver. The second mirror surface is adapted to focus collimated light upon the optical receiver. The precipitation sensor further includes an intermediate reflector in optical communication with the first mirror surface and with the second mirror surface.

Abstract: A sensing system for the detection and analysis of light and/or rain conditions affecting the vehicle has a mounting which can be installed within the scope of an assembly line production. The sensing system has a light sensor and a light sensor control unit and/or a rain sensor and a rain sensor control unit and a common carrier plate on which the light sensor with the light sensor control unit as well as the rain sensor with the rain sensor control unit can be mounted.

Abstract: It is prevented that a malfunction occurs because of a noise. A smoke detection section samples as a smoke detection signal a signal digitized after being output from a light reception section when a light emission section glows, and updates a previous smoke detection signal. A noise detection section samples as a noise detection signal a signal output from the light reception section when the light emission section is not driven to glow. When the noise detection signal exceeds a predetermined noise level, a noise de-influence unit disables updating of the previous smoke detection signal with the newly sampled smoke detection signal so as to process a noise.

Abstract: A smoke detector includes a housing defining a dark chamber admitting test atmosphere. A light receiver is disposed within the chamber. A scatter emitter is positioned within the chamber such that light strikes the receiver when reflected off particles suspended in the test atmosphere. An obscuration emitter is positioned within the chamber such that light emitted is directed to the receiver unless obstructed by particles suspended in the test atmosphere. A smoke detect signal is generated responsive to a measurement made responsive to the scatter emitter and/or the obscuration emitter.

Abstract: Disclosed is a sensing system and method utilizing a sensor cartridge (10) for making analytical measurements regarding one or more samples (50) of interest, the cartridge (10) comprising an opaque housing (12) having an opening (32), the opening (32) allowing access to one or more electrically conductive contacts (34) and one or more fluidic connectors (36) disposed within the housing (12) and mechanically aligned to the electrically conductive contacts (34), a flow cell (56) having one or more channels connected to the one or more fluidic connectors (36), and a fixed optic sensor (68, 58, 72, 74) disposed within said housing (12) and aligned to a sensing surface on the flow cell. The fixed optic sensor may be, for example, a surface plasmon resonance sensor, a critical angle sensor, or a fluorescence-based sensor. In one embodiment of the present invention, the one or more electrically conductive contacts (32) comprise card-edge contacts (34).

Abstract: A device for converting a position of a float member in a rotameter in to an electrical output. Light from a light source is collimated into parallel light rays, at either or both opposing sides of a rotameter tube to greatly enhance accuracy of readings. The lightrays passing through the tube are detected by a linear optical array. A range of movement capable of being read by the linear optical array is extended by use of either a fiber optical array or a movable illumination device and linear optic array. The collimator(s) may be a linear array of one or two rows of cylindrical lenses sandwiched between a pair of plates. The linear optic array maybe arranged on opposite sides of the rotameter tube or may be on the same side there of. A light guide is used in the latter arrangement to guide light from the light source to a side of the rotameter tube opposite the linear optic array which may be a charge-coupled device(CCD).

Abstract: A process is provided for improving the reliability of operation of optical gas sensors with at least one radiation source and with at least one radiation detector. By comparing and evaluating the measured signals (18) (D) sent by the radiation detector, of which there is at least one, with first, second and third stored reference values (D1, D2, K), it is achieved, on the one band, that in the case of toxic gas concentrations or of gas concentrations that are critical because of explosion hazard, second measured values (15) continue to be sent for the protection of the user corresponding to the range between the reference values D1 and D2 when the third reference value (K) is exceeded. On the other hand, at least first warning signals (16) are sent by the gas sensor to warn that a preset degree of contamination has been reached in order for maintenance or cleaning of the gas sensor to be performed or in order for the gas sensor to be replaced with a new gas sensor shortly.

Abstract: The present invention provides microfluidic devices and systems that utilize optical detection systems, and where one or more light altering optical elements are integrated into the body structure of the microfluidic device. The resulting devices perform at least a portion of the optical manipulations used in the optical detection method employed.

Abstract: A method for determining the particle concentration of a continuous medium in a receptacle, in which, a light beam from a light source is first directed through a particle-loaded, continuous medium, to the light-sensitive surface of a position-sensitive sensor, the light beam being so directed at the light-sensitive surface that the light scattered by the particles assuming, on the average, a different position than the unscattered light. The deviation of the midpoint of the scattered light on the light-sensitive surface from the midpoint of the unscattered light is subsequently determined, and this deviation is correlated to a specific particle concentration.

Abstract: The read head for luminometer includes a housing that encloses a cylindrical core. The housing has a through opening that aligns with a central passageway of the cylindrical core to define a confinement space. The housing and the cylindrical core are formed in two parts that diverge or converge with respect to each other under the influence of a manually controlled actuator member. When the housing parts and the core parts are in a closed convergent position an analytical line that extends through the housing and the core is maintained in a confined position within the confinement space of the housing and the core. Actuation of the housing parts and the core parts into a diverged open position opens the confinement space that accommodates the analytical line. The analytical line can thus be lifted away from the previous confinement space or reinstalled back into the open confinement space and then locked in place by an actuation of the housing parts into a closed converged position along with the core parts.

Abstract: The present invention refers to an apparatus for monitoring pipetting operations, and in particular the ejection of a first liquid from a pipetting needle having a tip immersed in a second liquid. The apparatus comprises a light source that irradiates the second liquid with a light beam, and light receiver which receives the light beam emerging from the second liquid and delivers an output signal which corresponds to the received light intensity. To improve the accuracy and reliability of pipetting operations, the apparatus is provided with a light receiver adapted for continuously delivering intensity signals (Un); first storage means for storing previously determined threshold values (S); second storage means for storing intensity signals (Un) delivered by the light receiver and evaluation parameters (Bm, Am/Atot) derived therefrom; and at least one logic circuit for comparing the evaluation parameters (Bm, Am/Atot) with the threshold values (S) and for delivering a resulting output signal (E, F).

Abstract: In a process for the quantitative detection of a given gas and in a device for the quantitative detection of a given gas, a gas sample (3), which may contain the given gas as a component, is irradiated with a diode laser (1) operating in a single mode and free of mode jumps, the wavelength of which being continuously tuned by varying the laser control current. The laser control current is varied by superimposing a sinus modulation current of a predetermined frequency to a periodically varied d.c. component so that a laser wavelength range is scanned in the area of the absorption line of the given gas. The intensity of the laser radiation after passing through the gas sample is measured by means of a detector. The d.c. component of the detector signal and the second harmonic of the detector signal corresponding to the doubled frequency of the sinus modulation current are determined.

Abstract: An apparatus in accordance with the invention is directed to an optical inspection apparatus (10) adapted to inspect a liquid sample. The apparatus includes a tray (20) that is adapted to be physically coupled to a first liquid sample carrier (22) and a second liquid sample carrier (40), each of the first and second liquid sample carriers (22, 40) being adapted to hold a liquid sample. The first liquid sample carrier (22) is of a first type and the second liquid sample carrier (40) is of a second type different from the first type. The apparatus (10) has a light source (108) adapted to illuminate one of the liquid samples associated with one of the liquid sample carriers (22 or 40) when the liquid sample carrier (22 or 40) is coupled to the tray (20) at an inspection location and a detector (110) adapted to receive light from the liquid sample when the liquid sample is being illuminated by the light source (108).

Abstract: A water drop detection device for detecting an amount of water drops present upon a surface of a transparent substrate in which a light source with a driver circuit guides light into the substrate so as to cause the light to under go internal reflection within the substrate. The light source has a light emitting element and a receiving light sensing element for detecting the light output from the emitting element. The light output from the light emitting element is modulated by a predetermined frequency. A signal corresponding to the modulated component is separated from the output signal of the receiving light sensing element. The output light emission of the light emitting element is maintained at a desired value by feeding the separated signal back to the driver circuit of the light emitting element.

Abstract: A method and system for multiple microphone photoacoustic leak detection and localization. The leak detection technique uses photoacoustic sounds produced by the interaction of a carbon dioxide (CO2) laser turned to 10.6 microns and a photoactive tracer gas, sulfur hexafluoride (SF6), emitted by calibrated leak sources. As the leaked gas is heated by the laser, it expands and launches a photoacoustic sound pulse. The sound pulses generated by the scanning process are recorded across a broad bandwidth by multiple ultra-sensitive microphones. After the photoacoustic pulses arc recorded, the magnitude is compared with background noise measurement at several frequencies for a determination if a leak is present. If the presence of a leak is found, then the location of the leak is determined. The recorded sound is processed by using Matched Field Processing (MFP) as the signal processing technique.

Abstract: A smoke detector includes a housing defining a dark chamber admitting test atmosphere. A light receiver is disposed within the chamber. A scatter emitter is positioned within the chamber such that light strikes the receiver when reflected off particles suspended in the test atmosphere. An obscuration emitter is positioned within the chamber such that light emitted is directed to the receiver unless obstructed by particles suspended in the test atmosphere. A smoke detect signal is generated responsive to a measurement made responsive to the scatter emitter and/or the obscuration emitter.

Abstract: This invention describes a method by which microparticles, typically in the size range from 0.3 &mgr;m to 100 &mgr;m, which are carried in a fluid suspension, may be rapidly detected and characterized. The method primarily relates to the measurement of atmospheric particles such as those in clouds or environmental aerosols, but it may be used to measure other forms of particulate suspension wherever the flow of suspension through a defined measurement space can be achieved. The method is based upon a rapid analysis of the spatial laser scattering profile (i.e., the complex manner in which individual particles scatter laser light) recorded from individual particles as they are carried in suspension through a measurement space. Using this method it is possible to differentiate various types of particles based on particle shape and structure, as manifest in characteristics of their individual spatial light scattering patterns.

Abstract: The invention relates to a gas sensor (A) which is adapted for evaluating the contents of a gas sample enclosed in a cavity (2) or a gas cell (1). The gas sensor has the form of a block in which the wall or wall-parts of a gas cell or cavity have highly light-reflective properties, designated mirror surfaces (11A, 12A). The cavity (2) has an opening (2a) for incoming light rays which are reflected in the cavity a predetermined number of times such as to create an optical analysis path before being caused to pass through an opening (6) for outgoing light rays, such reflections being achieved with the aid of three opposing, concave light-reflecting wall-parts (11, 12, 13). A first of the light-reflecting wall-parts (11) has the shape of part of an ellipsoid. A second (12) and a third (13) of the light-reflecting wall-parts have a common shape conforming to part of an ellipsoid.

Abstract: A modular flow cell having a high optical throughput, a long optical path length and a small cross-section. The modular flow cell configuration includes remote ports or connections for liquid and light input, and liquid and light output. The flow cell includes a flow cell body having two ends, each with a respective end interface secured thereto. The flow cell is configured to form a part of a modular flow cell assembly. The flow cell body includes a channel having a through-aperture with an inner surface. A light guiding material, e.g. a transparent fluoropolymer material having a refractive index less than the refractive index of common chromatography solvents, is disposed proximate to the channel to form a light guiding through-aperture in the flow cell body.

Abstract: An aspirated-type detector includes a housing with an internal ambient condition sensing region and a sensor carried therein. The housing is perforated with ambient atmosphere inflow ports. A fan or similar device lowers the pressure in the internal region thereby producing a positive inflow of adjacent, external ambient atmosphere into the sensing region. Alternatively, the fan can be operated to inject exterior ambient atmosphere into the sensing chamber under positive pressure. The fan can also be modularized. The detector can incorporate control circuitry for supervisory or signal processing purposes.

Abstract: A method and apparatus for non-invasively measuring a biological attribute, such as the concentration of an analyte, particularly a blood analyte in tissue such as glucose. The method utilizes spectrographic techniques in conjunction with an improved subject-tailored calibration model. In a calibration phase, calibration model data is modified to reduce or eliminate subject-specific attributes, resulting in a calibration data set modeling within--subject physiological variation, sample location, insertion variations, and instrument variation. In a prediction phase, the prediction process is tailored for each target subject separately using a minimal number of spectral measurements from each subject.

Abstract: An imaging apparatus includes a collection of optical elements arranged in a predetermined sequence and cooperable to define a dark-field optical arrangement and a bright-field optical arrangement. The dark-field optical arrangement and a bright-field optical arrangement may be defined along the same or different optical path(s). At least one of the optical elements is operative to enable at least one of the dark field or the bright-field optical arrangements. In a first embodiment said one optical element is movable from a first to a second position to enable either the dark-field or the bright-field optical arrangement. In a second embodiment said one optical element is operable to enable simultaneously both the dark-field and the bright-field optical arrangements. Both opaque objects and phase objects in a fluid stream are able to be detected and quantified.

Abstract: A method and an assembly for sensing moisture (20) on the exterior surface (22) of a sheet of glass (14) by positioning an imaging lens (16) adjacent to the interior surface (18) of the sheet of glass (14), passing light rays from moisture (20) on the exterior surface (22) of the sheet of glass (14) through the imaging lens (16) and producing first and second successive images of the moisture (20) on the glass (14), and successively directing the first and second images from the lens (16) onto a focal plane detector (12). The focal plane detector (12) is divided into rows of pixels (24) which are ligned into columns. The assembly and method are characterized by scanning the pixels (24) of each row in a first scan (FIG. 4) and producing a reference value X for each pixel (24) in response to an initial image in that pixel (24), scanning the pixels (24) of each row in a second scan (FIG.

Abstract: A waveguide-based sensing system includes a plurality of waveguides secured within a waveguide holder. Each waveguide has a sensing surface with athed analyte recognition elements. The end faces of the sensing surfaces are perpendicular (or at least approximately perpendicular) to the sensing surfaces. The sensing surfaces are directly excited by light directed normal thereto and emit optical signals responsive to the presence of an analyte. These optical signals are coupled into the waveguides. The optical signals travel along the length of the waveguides to the end surfaces, which integrate the optical signals over the length of the waveguides. The integrated optical signals emitted from the end surfaces of the fibers are then detected and analyzed.

Abstract: The invention concerns in particular, an instrument for measuring the refractive index of a fluid, particularly seawater. Its object is more specifically an instrument for measuring the refractive index of a fluid having a sensor machined to contain the fluid whose refractive index is to be measured, a coherent light source which illuminates the sensor via at least one beam of coherent light, a photodetector, and processor means with which the refractive index of the fluid can be determined from the interference fringes produced by transmission and/or reflection interferences of the beam at the various optical interfaces of the sensor.

Abstract: An ultraviolet and visible light absorbance detector uses a flow cell having a sample cell opening and a reference opening formed therethrough extending parallel to each other. The reference opening has a cross-sectional shape which is elongated in a direction perpendicular to the direction of its extension. An optical system causes an image of a slit to be formed with dispersed light over an area which includes light-receiving windows of both these openings, and portions of the dispersed light, after passing through these openings, are individually detected by light-receiving elements of a light-receiving device. Since the reference opening has an increased sectional area and its light throughput is increased, the absorbance noise due to the reference opening is reduced and the overall S/N ratio of the detector is improved.

Abstract: A gas turbine includes a compressor for compressing air and discharging compressed air. A combustor produces a hot gas by burning a fuel having a quality level in the compressed air. A turbine expands the hot gas produced by the combustor. A fuel delivery system delivers the fuel to the combustor. A fuel quality sensor senses the quality level of the fuel which is delivered to the combustor. A control and monitoring system stops delivery of the fuel as a function of the quality level, and stores a history of the quality level.

Abstract: A system for detecting the presence of rain droplets on a windshield employs a source of radiant energy, such as an LED, and a photodetector installed on the instrument panel of a vehicle. The LED and the photodiode are arranged with respect to one another such that light from the LED cannot reflect directly off the windshield onto the photodiode. Only when the light from the LED is back scattered by an environmental condition, such as the raindrops on the exterior of the windshield, the condensation of moisture on the interior of the windshield, or the presence of smoke in the cabin, will the photodiode receive the light from the LED. Each of these environmental conditions has a predeterminable characteristic signature that permits the processing of data to detect same.

Abstract: An apparatus for housing a submergible optical sensor is provided. The apparatus comprises a sensor body having a sensor opening. The sensor body is operable to protect a sensor when submerged in a fluid. A shutter is disposed above the sensor opening. A motor couples to the shutter and can rotate the shutter. A controller couples to the motor and is operable to cause the motor to rotate the shutter such that the sensor opening is exposed when the sensor takes a measurement. The controller is further operable to cause the motor to rotate the shutter such that the shutter covers the sensor opening when the sensor is not taking a measurement.

Abstract: The present invention provides microfluidic devices and systems that utilize optical detection systems, and where one or more light altering optical elements are integrated into the body structure of the microfluidic device. The resulting devices perform at least a portion of the optical manipulations used in the optical detection method employed.

Abstract: An optical device on board an aircraft for detecting icing conditions including an optical beam emitter to create at least one illuminated external volume of measurement through which there circulates a flow of air charged with water particles; a collector optical system for the collection of at least a part of the light beam back-scattered by the water particles (the external volume of measurement being located on the optical axis of said collector optical system); a photodetector for detecting back-scattered optical beams; a signal processor for processing the signal delivered by the photodetector to compute the severity of the icing conditions; an information provider for providing information on the calculated severity of the icing conditions. Advantageously, the optical means for the differentiation of device includes a differentiation for differentiating between liquid water particles and solid water particles, based on analysis of the polarization.

Abstract: A moisture sensor for detecting moisture on the surface of a transparent material. The moisture sensor includes one or more emitters for producing emitter signals which are influenced by moisture on the transparent material, and one or more detectors for receiving the emitter signals. The detector produces a detector output signal which is filtered and amplified in a pre-demodulation gain and filtering circuit to remove some of the unwanted signal components including noise from ambient light and EMI. Digital Signal Processing filtering is used after the moisture signal is demodulated to a dc signal to discern small signal changes due to moisture events in the presence of large amounts of the noise created by the pre-demodulation gain circuit. The DSP filtering includes a low pass filter stage and a band pass filter stage implemented by a microcomputer using First In First Out shift registers, summing elements and division elements.

Abstract: An automatic moisture sensing and watering system detects a moisture level within the soil. The automatic moisture sensing and watering system may be implemented in combination with a conventional automatic watering system to accurately control a moisture content of a plot of soil. Since a plant draws water directly from the soil, the automatic moisture sensing and watering system is adapted for controlling the moisture content of the soil itself, by measuring the moisture content within the soil. The watering period of an automatic watering system may be changed, based upon a detected moisture content within a plot of soil. Alternatively, an amount of water to be applied at a next watering period may be changed, based upon a detected moisture content within the plot of soil.

Abstract: The invention relates to a method of localizing an object in a turbid medium, utilizing an exponential function which determines the effect of an attenuation coefficient of a voxel of the turbid medium on an intensity of light transported through the turbid medium. In order to determine the estimated intensity variation on a photodetector, for each voxel the contribution to the intensity variation is determined by means of this exponential function. In order to reduce the required calculation time, this exponential function is approximated by a function which can be split into two orthogonal vectors. Consequently, the number of times that the value of an exponential function must be determined can be substantially reduced, resulting in a substantial reduction of the calculation time required for the reconstruction of an image of the interior of the turbid medium.

Abstract: A modulated light source (31) transmits light pulses through an optical channel (20) to an optical sensor (10) remotely located from the cockpit and mounted proximate an aerodynamic surface (14) of an aircraft. In the absence of ice a baseline amount of light is returned inward via the optical channel. When water, ice, or de-icing fluid covers the light sensor, a detectable variable amount of light pulses are returned by the sensor inward through the optical channel, and are detected by a light detector (34) which generates an electrical output signal that varies as a function of the type, amount, and rate of substance accretion. The output signal is visually displayed (37) and the pilot may also be audibly warned.

Abstract: A semiconductor light-emitting device which emits first light of a wavelength absorbed by a substance containing an OH group is sent toward a detection object. A semiconductor light-emitting device emits second visible light toward the detection object. A photoreceptor receives light from the detection object and acquires first and second received light-quantities derived from the respective ones of the first and second light. A processing system corrects the first photoreceiving quantity on the basis of the second photoreceiving quantity. The processing system determines the color of the detection object by the second photoreceiving quantity, and corrects the first photoreceiving quantity on the basis of this determination result. Further, it compares the corrected first photoreceiving quantity with a prescribed threshold value, detects whether or not water, which is the subject containing the OH group, is contained in the detection object, and outputs the same as an output signal.

Abstract: A data collection method for scanning a scan window comprising one or more channels is described. In the method of the invention an integrated signal (S) is measured across a scan window including one or more channels using an integrating detector. Next, a velocity-normalized integrated signal (Sn) is determined based on the integrated signal (S) and a scan velocity.

Abstract: Safety device composed of a radiation emitter, a radiation receiver disposed for receiving radiation which is produced by the emitter and which traverses a radiation path between the emitter and the detector, the detector producing an output signal representative of the quantity of radiation received by the detector, and an electronic circuit coupled to the detector for analyzing the output signal produced by the detector and identifying a reduction in the magnitude of the output signal as a result of an obstruction in the radiation path, wherein the emitter and the detector are mounted on a cooking appliance in a manner which allows extraneous radiation in the vicinity of the cooking appliance to traverse the radiation path.

Abstract: Method and apparatus for determining the opacity of exhaust plumes from moving emissions sources. In operation, a light source is activated at a time prior to the arrival of a diesel locomotive at a measurement point, by means of a track trigger switch or the Automatic Equipment Identification system, such that the opacity measurement is synchronized with the passage of an exhaust plume past the measurement point. A beam of light from the light source passes through the exhaust plume of the locomotive and is detected by a suitable detector, preferably a high-rate photodiode. The light beam is well-collimated and is preferably monochromatic, permitting the use of a narrowband pass filter to discriminate against background light. In order to span a double railroad track and provide a beam which is substantially stronger than background, the light source, preferably a diode laser, must provide a locally intense beam.

Abstract: A system and a method for monitoring fouling in a fluid stream are provided. A light source generates a light path directed to two distinct portions of a fluid stream, one of which includes a translucent conduit. The conduit experiences fouling on the walls thereof. The light directed towards the conduit is absorbed or scattered to a varying degree as a function of foulant thickness and composition and the wavelength of the light employed. A comparison of foulant contained in the fluid itself may be compared to the foulant in the conduit, and a signal representative thereof can be generated. As a result, dosage of agents added to the fluid stream to control the foulant in the system may be controlled.

Abstract: In a method of measuring a mass flow distribution of a flow over a measuring plane (8), a light section (5) extending parallel to and around the measuring plane is formed, the light section having a small thickness (7). A picture is recorded, vertically to the measuring plane and during a defined interval of time t, of particles carried by the flow and passing through the light section. The distribution of the images of the particles (4) in the picture is evaluated for the mass flow distribution.

Abstract: A coolant sealing structure for a solar cell of which the sealing property is maintained with high reliability in use for a long period. A solar cell has its light receiving surface and a reinforced portion formed around the fringe portion of the light receiving surface. The plate member is joined with the top of the reinforced portion by means of an anode joint process. A transparent member is joined with the plate member to form a coolant passage. This structure allows the solar cell to be directly cooled with the coolant flowing through the coolant passage. Since the solar cell is joined with the plate member, separation does not occur at the joined portion under repeated temperature changes. The coolant sealing structure can be used with high reliability for a long period.

Abstract: The invention features an apparatus and method for determining and controlling the concentration of a solute in a solute stream by measuring the concentration of an indicator agent.

Abstract: A recording apparatus capable of determining malfunction of an ink detection device such that a light emitting device of an ink detection sensor provided for the recording apparatus to detect ink depending upon whether ink traversing a detection optical axis exists is periodically operated to emit light. Malfunction of the ink detection sensor is determined in accordance with the quantity of light received by a light receiving device in a state where ink traversing the detection optical axis is not discharged.

Abstract: A contamination sensor is provided for use in a fluid system and machinery to continuously monitor the level of contaminants in a fluid. The contamination sensor includes a source of light that is directed into the fluid stream with three photodetector arrangements detecting light scattered by contaminants contained in the fluid. The first photodetector arrangement is located near the origin of the source of light. The second photodetector arrangement is located farther away from the source of light. The third photodetector arrangement is located perpendicular to the axis of the light beam and spaced from the source of light along the axis of the light beam. The simultaneous detected scattered light from a contaminant in the fluid is converted to electrical signals by the photodetectors, conditioned by a signal conditioning circuit and transferred to a signal processing unit for interpretation.

Abstract: An aspirated-type detector includes a housing with an internal ambient condition sensing region and a sensor carried therein. The housing is perforated with ambient atmosphere inflow ports. A fan or similar device lowers the pressure in the internal region thereby producing a positive inflow of adjacent, external ambient atmosphere into the sensing region. Alternatively, the fan can be operated to inject exterior ambient atmosphere into the sensing chamber under positive pressure. The fan can also be modularized. The detector can incorporate control circuitry for supervisory or signal processing purposes.

Abstract: A method of detecting the content of impurity in a gaseous medium has the steps of continually detecting impurities in the gaseous medium, emitting analyzing signals that vary with variation in impurity content, and statistically analyzing the emitted signals. When statistically analyzing the emitted signals, newer signals are accorded greater influence on outputs than are older signals, which become gradually less influential.

Abstract: The invention concerns a method and device for checking tightness of containers, housings and similar test objects (15). The test object (15) is subjected to a pressurized test gas. If a leak (28) is present, test gas escapes from the text object (15) and is exposed in a test chamber (18) to an intensity-modulated electromagnetic wave field emitted by a laser (1). The wave field contains frequency components which are absorbed by the test gas to produce a photo-acoustic signal indicative of the presence of a leak.