| alkali |
A non-acidic substance that dissolves in water and increases the pH of a solution. Alkalis can form corrosive salts. |
| blind zone |
An area directly in front of the sensor face in which objects cannot be detected because they are too close. |
| convergent beam scan |
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. |
| dark operate mode |
A photoelectric scanning mode in which a target is detected when light is blocked from the receiver. |
| diffuse mode |
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. |
| diffuse scan |
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. |
| direct scan |
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. |
| electromagnetic interference |
The disruption of transmission or reception of a signal caused by electrical and magnetic fields. |
| emitter |
A fiber optic cable that transmits a beam of light. |
| excess gain |
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. |
| eye |
The window or lens of a photoelectric sensor. |
| fiber optic cable |
A cable packed with thin, flexible glass or plastic optical fibers that transmit light instead of electricity. |
| hydraulic fluid |
A viscous liquid, typically oil, used in industrial applications. |
| infrared light |
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. |
| light emitting diode |
A semiconductor device that emits a narrow spectrum of light in a forward direction. Also known as LED. |
| light operate mode |
A photoelectric scanning mode in which a target is detected when light from the transmitter reaches the receiver. |
| load current |
The current drawn by a sensor when it is energized. Most photoelectric sensors cannot handle more than .5 amps of current. |
| load-powered |
Drawing operating current through a load. |
| minimum holding current |
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. |
| mutual interference |
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. |
| N-doped |
Silicon that has been given a negative charge through the addition of other substances. |
| NPN transistor |
A transistor with one layer of positively charged semiconductor material between two negatively charged layers. |
| off-state leakage current |
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. |
| operating current |
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. |
| organic solvent |
Solvents that are organic compounds and contain carbon atoms. The most common organic solvent is water. |
| P-doped |
Silicon that has been given a positive charge through the addition of other substances. |
| photoelectric sensor |
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. |
| photoreceiver |
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. |
| phototransmitter |
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. |
| PNP transistor |
A transistor with one layer of negatively charged semiconductor material between two positively charged layers. |
| polarized scan |
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. |
| position sensor detector |
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. |
| radial |
Radiating outward in all directions from a common center. |
| receiver |
A fiber optic cable that receives a beam of light. |
| reflective scan |
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. |
| reflectivity value |
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%. |
| reflex mode |
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. |
| residual current |
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. |
| retroreflective scan |
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. |
| scanning |
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. |
| semiconductor |
Silicon crystal that is transformed from an insulator into a conductor. Semiconductors are not as conductive as other materials, such as copper. |
| silicon |
A natural element that forms crystals easily and does not conduct electric current. This makes a silicon an insulator. |
| solid state relay |
An electronic switch that contains no moving parts. Solid state relays are rapidly replacing electromechanical relays. |
| solid state relay |
An electronic relay with no moving parts. |
| specular scan |
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. |
| switching zone |
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. |
| target |
The object or property being detected by a sensor. |
| thru-beam mode |
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. |
| thru-beam scan |
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. |
| thyristor |
A solid-state switching device for semiconductors to convert AC current in one of two directions controlled by an electrode. |
| transistor |
A device used to amplify a signal or open and close a circuit. |
| triac |
An electronic switch that allows small control voltages and currents to switch very large voltages. Triacs conduct in either direction. |
| ultrasonic sensor |
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. |
| viscosity |
A fluid's resistance to flow. Viscosity is used to describe friction of fluid. |
| white light |
Light containing equal amounts of the primary colors. The human eye sees this light as colorless. Sunlight is white light. |