[A]
[B]
[C] [D]
[E] [F]
[G] [H]
[I] [J]
[K] [L]
[M] [N]
[O] [P]
[Q] [R]
[S] [T]
[U] [V]
[W] [X]
[Y] [Z]
Q
Quiescent
Supply Current-the
supply current being drawn when the pressure sensor
is at null.
[Top
of page]
Ratiometric
(Ratiometricity Error)-at
a given supply voltage, sensor output is a proportion
of that supply voltage. Ratiometricity error is the
change in this proportion resulting from any change
to the supply voltage. Usually expressed as a percent
of full scale output.
Range-the
measurand values over which the sensor is intended to
measure, specified by the upper and lower limits.
Rectifier-a
device that converts alternating current into direct
current.
Reed
Technology-technology where the reed contacts
are designed to be actuated by a magnet. When a magnetic
field is brought close to the reed contacts, the contacts
are drawn together to make the circuit.
Reflective
Scan-a scanning technique in which the light
source is aimed at a reflective surface to illuminate
the photosensor. Retroreflective, specular, diffuse
scan and convergent beam are all reflective scan techniques.
Regulation
%-the ratio of voltage extremes due to loading
or line fluctuations. The process of holding constant
a quantity such as voltage by means of a system that
automatically corrects errors. For example, as more
current is drawn from a battery or power supply, the
output voltage tends to decrease (load regulation).
With a power supply derived from AC, the DC output voltage
can vary with the variation in AC voltage (line regulation).
Release
Force-the level to which force on the plunger
must be reduced to allow the contacts to snap from the
operated contact position to the normal contact position.
Release
Point-that position of the plunger at which
the contacts snap from the operated contact position
to the normal contact position.
Release
Travel-as an operating characteristic of a switch,
release travel is the distance through which the plunger
moves when traveled from the release point to the free
position. As a characteristic of the actuation applied
to the switch, release travel is the distance the plunger
is released past the release point.
Repeatability-the
ability of a sensor to reproduce output readings when
the same value is applied to it consecutively in the
same direction, for a specified number of cycles, or
specified time duration.
Resolution-the
magnitude of output step changes as the pressure is
continuously varied over the range. This term applies
primarily to potentiometric sensors. Resolution is best
specified as average and maximum resolution. Usually
expressed in percent of full scale output.
Response
Time-the time it takes for a device to respond
to an input signal. The sum of the sensor, amplifier,
and output response is the total response time.
Retroreflective
Scan-the reflective scan technique that uses
a special reflector (retroreflector) to return light
along the same path it was sent.
Reverse
Polarity Protection-circuitry, usually a diode
which prevents current from flowing into the control
in case of accidental mis-wiring of the plus (+) or
minus (-) terminals, preventing damage to the unit.
Ripple-the
alternating component of voltage from a rectifier or
generator. A slight fluctuation in the intensity of
a steady current.
Rise
Time-a measure (10% to 90%) of the time required
for an output voltage to rise from a state of low voltage
to a high voltage level, once a level change has started.
Room
Conditions-ambient environmental conditions
under which sensors must commonly operate, which have
been established as follows:
(a) Temperature:
25 + -10 %C (77 + - 18 degrees F).
(b) Relative
humidity: 90% or less.
(c) Barometric
pressure: 26 to 32 inches Hg.
Note: Tolerances
closer than shown are frequently specified for sensor
calibration and test environments.
[Top
of page]
Saturation
Voltage-the
voltage drop appearing across a control device that
is fully turned On.
Scan
Technique-a method of scanning objects. The
two general categories are through and reflective scan.
Self-Contained
Control-a photoelectric control in which all
three phases of control - sensing, signal conditioning,
and output - occur in a single device.
Self-Contained
Sensor-a proximity sensor in which all three
phases of control, sensing, signal conditioning, and
output, occur in a single device.
Sensing
Distance-the maximum recommended distance between
the sensor and standard target at which sensor will
effectively and reliably detect the target.
Sensing
Element-that part of a sensor which responds
directly to changes in input pressure.
Sensitivity-maximum
recommended distance between the sensor and standard
target at which sensor will effectively and reliably
detect the target.
Sensitivity
Shift-a change in sensitivity resulting from
an environmental change such as temperature.
Sensor-a
sensing element. The basic element that usually changes
some physical parameter to an electrical signal.
Series
Circuit-a circuit in which current has only
one path to follow.
Shielded
Sensor-a sensor which "senses" only to the front
of its face and ignores metals to its side. The presence
of such side metal, however, may cause a slight shift
in operating characteristics.
Signal
Conditioning-to process the form or mode of
a signal so as to make it intelligible to or compatible
with, a given device, including such manipulation as
pulse shaping, pulse clipping, digitizing, and linearizing.
Signal
Ratio-1) broadly, the comparison of light seen
by a photosensor when the beam is blocked to the light
seen when the beam is not blocked; 2) More specifically,
the comparison of photocell resistance when sensor is
dark to when it is illuminated. Proper control application
involves establishing a large dark-to-light ratio.
Single-Pole
Double-Throw (SPDT)-switch which may either
make or break a circuit, depending on how it is wired.
Single-Pole
Single-Throw (SPST)-switch with only one moving
and one stationary contact. Available either normally
open (N.O.) or normally closed (N.C.).
Shock,
Mechanical-a short pulse of acceleration, usually
lasting only a few milliseconds. A typical shock test
pulse is a half-sine acceleration wave having 100g peak
and .007 second duration.
Slide-By-the
condition whereby the target approaches the sensing
face of the proximity sensor in such a direction that
its center will cross the axis of the sensing face at
right angles.
Slight
Contamination-indoor locations, non-industrial
areas, office buildings.
Snap
Action-in strict terms, snap action is a property
of a switch such that the moving contact accelerates
without added travel of the plunger beyond that travel
which was required to separate the contacts. National
Electrical Manufacturers Association defines snap action
as "a rapid motion of the contacts from one position
to another position, or their return. This action is
relatively independent of the rate of travel of the
actuator." The word "relatively" is important. In actual
fact, the acceleration of the moving contact is partially
dependent upon the velocity of the plunger. The important
point is that, once the plunger reaches the operating
or release point, the movable contact immediately transfers
to its opposite position without further travel of the
plunger. A non-snap acting switch lacks this feature.
Span-the
algebraic difference between limits of the pressure
range.
Specular
Scan-a reflective scan technique in which reflection
from a shiny surface illuminates the photosensor, which
must be precisely positioned to receive the reflected
light. The angle of incidence equals the angle of reflection.
Stability
of an Operating Characteristic-the extent to
which an operating characteristic such as operating
point remains constant during a specified number of
cycles of switch operation, under specified conditions
of actuation, electrical loading and environment. Most
clearly expressed as a graph of the characteristic versus
cycles of switch operation.
Standard
Target-an object used for making comparative
measurements of operating distance. A square of mild
steel, 1mm thick. The length of the side of the square
is equal to either:
A: the diameter
of the circle inscribed on the active surface of the
sensitive face of the sensor, or
B: three times
the rated operating distance, whichever is the greater.
Storage
Temperature Range-the minimum and maximum specified
temperature which may be applied to the pressure sensor
without causing a permanent change in the output characteristics.
Strain
Gage-a sensing device providing a change in
electrical resistance proportional to the level of applied
stress.
Sublimation-the
change of state of a materiel from solid to vapor and
back to solid without going through a liquid state.
Supply
Current-units = Amps or milliamps. The amount
of current necessary to maintain operation of a photoelectric
control, proximity sensor or control base. Sometimes
referred to as Current Consumption.
Supply
Voltage-units + Volts. The range of power required
to maintain proper operation of a photoelectric control,
proximity sensor or control base. The difference in
potential (or range of difference in potential) necessary
to operate the unit.
Switching
Frequency-the actual number of targets to which
the sensor can respond in a given time period, usually
expressed as Hertz (cycles per second).
[Top
of page]
Target-the
part or piece being detected.
Terminal
Base Linearity-T.B.L. (End Point Linearity)
- a method of defining linearity. The maximum deviation
of any data point on a sensor output curve from a straight
line drawn between the end data points on that output
curve. (T.B.L. is approximately twice the magnitude
of B.F.S.L.).
Terminal
Line-a theoretical slope for which the theoretical
end points are normalized at 0 and 100% of both measurand
and output. Interchangeability error is referenced to
this line.
Temperature
Error-the maximum change in output, at any input
pressure within the specified range, resulting from
a change in temperature.
Thermal
Drift Chart-a chart illustrating sensor operating
variance due to changes in temperature.
Thick-Film-technology
using silk screened pastes to form conductor, resistor,
themistors, and insulator patterns; screened onto the
substrate (usually ceramic) and cured by firing at elevated
temperatures.
Thin
Film-a technology using vacuum deposition of
conductors and dielectric materials onto a substrate
(frequently silicon) to form an electrical circuit.
Threshold
Response-a control type that responds to the
change in input signal level. Plug-in amplifiers are
either threshold or transition responsive.
Throw-the
number of circuits that each individual pole of a switch
can control. The number of throws is completely independent
of the number of poles and number of breaks. A single-pole
double-throw single-break switch connects the common
terminal of the switch to the normally closed terminal
when the plunger is free, but connects the common terminal
to the normally open terminal when the plunger is depressed.
A single-pole single-throw single-break switch has a
common terminal and either a normally open terminal
or a normally closed terminal but not both.
Thru
Scan-a scanning technique in which the emitter
(light source) is aimed directly at the receiver. Also
called direct scan and transmitted scan, since light
is transmitted directly, not reflected to the sensor.
Presently, it is the only scanning technique commonly
used to scan distances greater than 40 feet.
Time
Delay Before Availability-also know as False
Pulse Protection. Outputs are turned Off when power
is first applied during this time period.
Total
Travel-the distance from the plunger free position
to the full overtravel point.
Transducer-a
fully packaged, signal conditioned, compensated and
calibrated sensor.
Transient
Protection-circuitry to guard against spikes
induced on the supply lines by inductive sources such
as heavy motors or solenoids turning On and Off.
Transients-in
electronic usage, usually refers to an unwanted, temporary,
large increase or decrease in a current or supply voltage
that only occurs occasionally. Almost always due to
reactive components during rapid changes in voltage
or current.
Transition
Responsive-a control type that responds to the
rate of change in light intensity rather than the level
change. Used to detect fast moving objects that cause
little change in light intensity level.
Translucent-allows
light to pass through. Detecting translucent objects
is often best done with retroreflective scan, during
which the light must pass through the object twice,
thereby causing more of a signal change (larger signal
ratio).
Transmitter-a
transducer with a current loop output, typically 4 to
20 mA, enabling transmission of a signal over a longer
distance.
TTL-a
generic term for Transistor Logic which is used extensively
in digital electronics systems.
TTL
Compatibility-TTL (transistor-transistor-logic)
requires NPN (current sinking) input signals. Reliable
operation demands maximum input sensor voltage drop
of 0.8 V. Most TTL compatible interface devices have
voltage drops of less than 0.7V.
Typical-(as
used herein): refers to the target value or where a
range is given, represents an estimate of where 2/3
of the total population of several production runs would
be.
[Top
of page]
UL-Underwriter's
Laboratories, Inc., a non-profit organization that establishes,
maintains and operates laboratories for the examination
and testing of devices, systems and materials primarily
for safety.
Unidirectional
Differential Pressure Sensor-a differential
pressure sensor requiring the greater input pressure
to be applied to a specified pressure port.
Unshielded
Sensor-a sensor with limited side and front
sensing capabilities.
Usable
Sensing Distance-sensing distance after temperature
range tolerance and manufacturers tolerance are taken
into account.
[Top
of page]
Velocity-the
rate at which the position of a moving object is changing.
Velocity has two characteristics: magnitude (speed)
and direction.
Voltage-units
= Volts (DC) or Volts RMS (AC). The term used to designate
the electrical energy, differential that exists between
two points and is capable of producing the flow of current
when a closed path is connected between the two points.
Voltage
Drop-units = Volts (DC) or Volts RMS (AC). Sometimes
referred to as Saturation Voltage. In any solid state
control that switches a load, there will be some voltage
dropped across the output. This voltage drop or saturation
voltage will often vary with the amount of current going
through the output section and the load. It should be
specified with current conditions.
[Top
of page]
Welding,
Contact-one
of several conditions that may cause switch contacts
to fail to separate at the intended point of plunger
travel. As the name implies, the contacts literally
are welded together as a result of the electrical and
thermal effects at the contact interface.
[Top
of page]
[Top
of page]
[Top
of page]
[Top
of page]
