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alkali
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A non-acidic substance that dissolves in water and increases the pH of a solution. Alkalis can form corrosive salts.
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blind zone
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An area directly in front of the sensor face in which objects cannot be detected because they are too close.
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convergent beam scan
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A photoelectric scanning technique in which a position sensor detector mounted on the receiver measures the angle of light as it bounces off the target and uses this information to suppress backgrounds beyond a specified distance.
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dark operate mode
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A photoelectric scanning mode in which a target is detected when light is blocked from the receiver.
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diffuse mode
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An ultrasonic sensing mode in which the emitter bounces a sound wave off a target. Diffuse mode is the standard mode of operation for ultrasonic sensors.
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diffuse scan
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A photoelectric scanning technique in which a small amount of light is transmitted toward a target and the scattered reflected light is used to detect presence.
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direct scan
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A photoelectric scanning technique in which a beam of light shines directly from the transmitter to the receiver. An object is detected when it passes between transmitter and receiver and blocks the beam of light.
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electromagnetic interference
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The disruption of transmission or reception of a signal caused by electrical and magnetic fields.
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emitter
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A fiber optic cable that transmits a beam of light.
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excess gain
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The additional amount of light required by a sensor in a contaminated environment to achieve the same level of detection as in a clean environment.
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eye
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The window or lens of a photoelectric sensor.
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fiber optic cable
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A cable packed with thin, flexible glass or plastic optical fibers that transmit light instead of electricity.
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hydraulic fluid
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A viscous liquid, typically oil, used in industrial applications.
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infrared light
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An area outside of the visible part of the color spectrum, beyond red. Infrared is often used for an invisible wireless connection between devices, like TV remote controllers.
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light emitting diode
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A semiconductor device that emits a narrow spectrum of light in a forward direction. Also known as LED.
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light operate mode
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A photoelectric scanning mode in which a target is detected when light from the transmitter reaches the receiver.
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load current
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The current drawn by a sensor when it is energized. Most photoelectric sensors cannot handle more than .5 amps of current.
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load-powered
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Drawing operating current through a load.
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minimum holding current
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The amount of current required for a photoelectric sensor to operate. Most photoelectric sensors need a minimum current of 3 mA to 20 mA in order to function properly.
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mutual interference
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Interference between two sensors when the signal from one sensor is unintentionally picked up by another sensor nearby. Mutual interference can cause poor sensor performance or false outputs.
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N-doped
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Silicon that has been given a negative charge through the addition of other substances.
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NPN transistor
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A transistor with one layer of positively charged semiconductor material between two negatively charged layers.
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off-state leakage current
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Also known as load current and residual current. The amount of current required to keep a sensor active when it is not detecting a target.
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operating current
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Also known as off-state leakage current and residual current. The amount of current required to keep a sensor active when it is not detecting a target.
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organic solvent
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Solvents that are organic compounds and contain carbon atoms. The most common organic solvent is water.
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P-doped
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Silicon that has been given a positive charge through the addition of other substances.
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photoelectric sensor
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A type of sensor that detects the presence of an object through the use of a beam of light. Photoelectric sensors have an extremely broad sensing range, from a few millimeters to 100 feet away.
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photoreceiver
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The part of a photoelectric sensor that detects a beam of light. The phototreceiver may be in a separate unit, or enclosed in the same unit as the phototransmitter.
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phototransmitter
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The part of a photoelectric sensor that emits a beam of light. The phototransmitter may be in a separate unit, or enclosed in the same unit as the photoreceiver.
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PNP transistor
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A transistor with one layer of negatively charged semiconductor material between two positively charged layers.
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polarized scan
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A photoelectric scanning technique that uses special filters to absorb glare and reduce or eliminate reflections. Polarized scans filter out all unwanted light sources and detect only depolarized light.
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position sensor detector
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A device mounted on a photoreceiver that determines the distance of a target by measuring the angle of light as it bounces off a target.
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radial
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Radiating outward in all directions from a common center.
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receiver
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A fiber optic cable that receives a beam of light.
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reflective scan
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A photoelectric scanning technique in which light from the transmitter bounces off a reflector placed outside of the housing and travels back to the receiver. Also known as a retroreflective scan.
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reflectivity value
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A numeric value signifying the amount of light reflected from an object. A white test card has a reflectivity value of 100%, while printed newspaper that absorbs light has a reflectivity value of 60%.
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reflex mode
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An ultrasonic mode of operation in which sound waves are transmitted toward a reflector and bounce back to a receiver. An object is detected when it passes between the sensor and reflector and blocks the sound waves.
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residual current
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Also known as off-state leakage current and load current. The amount of current required to keep a sensor active when it is not detecting a target.
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retroreflective scan
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A photoelectric scanning technique in which light from the transmitter bounces off a reflector placed outside of the housing and travels back to the receiver. Also known as a reflective scan.
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scanning
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The process of detecting changes in the intensity of a beam of light in order to sense an object. Scanning technique is determined by the distance and physical properties of a target.
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semiconductor
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Silicon crystal that is transformed from an insulator into a conductor. Semiconductors are not as conductive as other materials, such as copper.
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silicon
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A natural element that forms crystals easily and does not conduct electric current. This makes a silicon an insulator.
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solid state relay
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An electronic switch that contains no moving parts. Solid state relays are rapidly replacing electromechanical relays.
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solid state relay
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An electronic relay with no moving parts.
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specular scan
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A photoelectric scanning technique in which light from the transmitter bounces off a shiny object and travels up to the receiver at exactly the same angle.
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switching zone
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The area the target must enter in order to be detected. The switching zone is determined by the diameter of light emitted from the transmitter.
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target
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The object or property being detected by a sensor.
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thru-beam mode
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An ultrasonic sensing mode in which the transmitter sends a sound wave toward the receiver. An object is detected when it passes between the transmitter and receiver and blocks the sound waves.
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thru-beam scan
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A photoelectric scanning technique in which a beam of light shines directly from the transmitter to the receiver. An object is detected when it passes between transmitter and receiver and blocks the beam of light.
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thyristor
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A solid-state switching device for semiconductors to convert AC current in one of two directions controlled by an electrode.
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transistor
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A device used to amplify a signal or open and close a circuit.
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triac
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An electronic switch that allows small control voltages and currents to switch very large voltages. Triacs conduct in either direction.
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ultrasonic sensor
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A type of sensor that uses sound waves to detect a target. Ultrasonic sensors are the best type of sensor for detecting liquids, clear objects, or irregularly shaped objects.
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viscosity
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A fluid's resistance to flow. Viscosity is used to describe friction of fluid.
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white light
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Light containing equal amounts of the primary colors. The human eye sees this light as colorless. Sunlight is white light.
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