In this section, the following term is used with the meaning indicated:
"variable" (as a noun) means a feature or property (e.g., a dimension, a physical condition such as temperature, a quality such as density or colour) which, in respect of a particular entity (e.g., an object, a quantity of a substance, a beam of light) and at a particular instant, is capable of being measured; the variable may change, so that its numerical expression may assume different values at different times, in different conditions or in individual cases, but may be constant in respect of a particular entity in certain conditions or for practical purposes (e.g., the length of a bar may be regarded as constant for many purposes).
Attention is drawn to the definitions of terms or expressions used, appearing in the notes of several of the classes in this section, in particular those of "measuring" in class Fulltext... Hierarchy... Expanded...G01 and "control" and "regulation" in class Fulltext... Hierarchy... Expanded...G05.
Classification in this section may present more difficulty than in other sections, because the distinction between different fields of use rests to a considerable extent on differences in the intention of the user rather than on any constructional differences or differences in the manner of use, and because the subjects dealt with are often in effect systems or combinations, which have features or parts in common, rather than "things", which are readily distinguishable as a whole. For example, information (e.g., a set of figures) may be displayed for the purpose of education or advertising (Fulltext... Hierarchy... Expanded...G09), for enabling the result of a measurement to be known (Fulltext... Hierarchy... Expanded...G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (Fulltext... Hierarchy... Expanded...G08). The words used to describe the purpose depend on features that may be irrelevant to the form of the apparatus concerned, for example, such features as the desired effect on the person who sees the display, or whether the display is controlled from a remote point. Again, a device which responds to some change in a condition, e.g., in the pressure of a fluid, may be used, without modification of the device itself, to give information about the pressure (Fulltext... Hierarchy... Expanded...G01L) or about some other condition linked to the pressure (another subclass of class Fulltext... Hierarchy... Expanded...G01, e.g., Fulltext... Hierarchy... Expanded...G01K for temperature), to make a record of the pressure or of its occurrence (Fulltext... Hierarchy... Expanded...G07C), to give an alarm (Fulltext... Hierarchy... Expanded...G08B), or to control another apparatus (Fulltext... Hierarchy... Expanded...G05).
The classification scheme is intended to enable things of a similar nature (as indicated above) to be classified together. It is therefore particularly necessary for the real nature of any technical subject to be decided before it can be properly classified.
This class covers, in addition to "true" measuring instruments, other indicating or recording devices of analogous construction, and also signalling or control devices insofar as they are concerned with measurement (as defined in Note 2 below) and are not specially adapted to the particular purpose of signalling or control.
In this class, the following term is used with the meaning indicated:
"measuring" is used to cover considerably more than its primary or basic meaning. In this primary sense, it means finding a numerical expression of the value of a variable in relation to a unit or datum or to another variable of the same nature, e.g. expressing a length in terms of another length as in measuring a length with a scale; the value may be obtained directly (as just suggested) or by measuring some other variable of which the value can be related to the value of the required variable, as in measuring a change in temperature by measuring a resultant change in the length of a column of mercury. However, since the same device or instrument may, instead of giving an immediate indication, be used to produce a record or to initiate a signal to produce an indication or control effect, or may be used in combination with other devices or instruments to give a conjoint result from measurement of two or more variables of the same or different kinds, it is necessary to interpret "measuring" as including also any operation that would make it possible to obtain such a numerical expression by the additional use of some way of converting a value into figures. Thus the expression in figures may be actually made by a digital presentation or by reading a scale, or an indication of it may be given without the use of figures, e.g. by some perceptible feature (variable) of the entity (e.g. object, substance, beam of light) of which the variable being measured is a property or condition or by an analogue of such a feature (e.g. the corresponding position of a member without any scale, a corresponding voltage generated in some way). In many cases there is no such value indication but only an indication of difference or equality in relation to a standard or datum (of which the value may or may not be known in figures); the standard or datum may be the value of another variable of the same nature but of a different entity (e.g. a standard measure) or of the same entity at a different time.
In its simplest form, measurement may give merely an indication of presence or absence of a certain condition or quality, e.g. movement (in any direction or in a particular direction), or whether a variable exceeds a predetermined value.
Attention is drawn to the Notes following the title of section G, especially as regards the definition of the term "variable".
In many measuring arrangements, a first variable to be measured is transformed into a second, or further, variables. The second, or further, variables may be (a) a condition related to the first variable and produced in a member, or (b) a displacement of a member. Further transformation may be needed. [6]
When classifying such an arrangement, (i) the transformation step, or each transformation step, that is of interest is classified, or (ii) if interest lies only in the system as a whole, the first variable is classified in the appropriate place. [6]
This is particularly important where two or more conversions take place, for instance where a first variable, for example pressure, is transformed into a second variable, for example an optical property of a sensing body, and that second variable is expressed by means of a third variable, for example an electric effect. In such a case, the following classification places should be considered: the place for the transformation of the first variable, that for sensing the condition caused by that variable, subclass Fulltext... Hierarchy... Expanded...G01D for expression of the measurement, and finally the place for the overall system, if any. [6]
The measurement of change in the value of a physical property is classified in the same subclass as the measurement of that physical property, e.g. measurement of expansion of length is classified in subclass Fulltext... Hierarchy... Expanded...G01B.
by measuring elastic deformation of gauges, e.g. of springs
G01L 1/08
·
by the use of counterbalancing forces
G01L 1/10
·
by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings (using resistance strain gauges Fulltext... Hierarchy... Expanded...G01L 1/20)
G01L 1/12
·
by measuring variations in the magnetic properties of materials resulting from the application of stress
G01L 1/14
·
by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
G01L 1/16
·
using properties of piezo-electric devices
G01L 1/18
·
using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material (resistance strain gauges for measuring linear expansion or contraction Fulltext... Hierarchy... Expanded...G01B)
G01L 1/20
·
by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids (of piezo-resistive materials Fulltext... Hierarchy... Expanded...G01L 1/18); by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
G01L 1/24
·
by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis
Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload
P:120
G01L 3/00
Measuring torque, work, mechanical power, or mechanical efficiency, in general
G01L 3/02
·
Rotary-transmission dynamometers
G01L 3/04
· ·
wherein the torque-transmitting element comprises a torsionally-flexible shaft
G01L 3/10
· · ·
involving electric or magnetic means for indicating
G01L 3/12
· · · ·
involving photoelectric means
G01L 3/16
·
Rotary-absorption dynamometers, e.g. of brake type
for measuring the force applied to control members, e.g. control members of vehicles, triggers
G01L 5/24
·
for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed (arrangements in wrenches or screwdrivers Fulltext... Hierarchy... Expanded...B25B 23/14)
G01L 5/26
·
for determining the characteristic of torque in relation to revolutions per unit of time
Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means (measuring differences of two or more pressure values Fulltext... Hierarchy... Expanded...G01L 13/00; measuring two or more pressure values simultaneously Fulltext... Hierarchy... Expanded...G01L 15/00; vacuum gauges Fulltext... Hierarchy... Expanded...G01L 21/00)
G01L 9/02
·
by making use of variations in ohmic resistance, e.g. of potentiometers
G01L 9/04
· ·
of resistance strain gauges
G01L 9/06
· ·
of piezo-resistive devices
G01L 9/08
·
by making use of piezo-electric devices
G01L 9/10
·
by making use of variations in inductance
G01L 9/12
·
by making use of variations in capacitance
G01L 9/14
·
involving the displacement of magnets, e.g. electromagnets
G01L 9/16
·
by making use of variations in the magnetic properties of material resulting from the application of stress
G01L 9/18
·
by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electric potential is produced or varied upon the application of stress
Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
G01L 19/04
·
Means for compensating for effects of changes of temperature
G01L 19/06
·
Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
P:10
G01L 21/00
Vacuum gauges
P:20
G01L 23/00
Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
P:100
G01L 25/00
Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency [2]
P:0
G01L 27/00
Testing or calibrating of apparatus for measuring fluid pressure [2]