G
SECTION G — PHYSICS
 G

Note(s)

  1. 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).
  2. 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 G01 and "control" and "regulation" in class G05.
  3. 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 (G09), for enabling the result of a measurement to be known (G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (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 (G01L) or about some other condition linked to the pressure (another subclass of class G01, e.g., G01K for temperature), to make a record of the pressure or of its occurrence (G07C), to give an alarm (G08B), or to control another apparatus (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.

  
INSTRUMENTS
 G01
MEASURING; TESTING
 G01

Note(s)

  1. 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.
  2. 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.

  3. Attention is drawn to the Notes following the titles of class B81 and subclass B81B relating to "micro-structural devices" and "micro-structural systems" and the Notes following the title of subclass B82B relating to "nano-structures". [7]
  4. Attention is drawn to the Notes following the title of section G, especially as regards the definition of the term "variable".
  5. 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 G01D for expression of the measurement, and finally the place for the overall system, if any.  [6]

  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 G01B.
 G01L
MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (methods or devices for measuring specially adapted for metal-rolling mills B21B 38/00; sensing pressure changes for compensating measurements of other variables or for compensating readings of instruments for variations in pressure, see  G01D or other relevant subclasses for the variable measured; weighing G01G;  converting a pattern of forces into electrical signals G06K 11/00)  [4]
 G01L

Note(s)

Attention is drawn to the Notes following the title of class G01.

 G01L
Subclass index
MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY
General methods; apparatus adapted to special purposes 1/00, 3/00; 5/00
MEASURING FLUID PRESSURE
Methods of measuring 7/00, 9/00, 11/00
Measurements of differential or multiple pressure values 13/00, 15/00
Details of apparatus or accessories 19/00
SPECIAL ADAPTATIONS OF MEASURING APPARATUS
Measurements of pressure of inflated bodies 17/00
Vacuum gauges 21/00
INDICATORS OF FAST CHANGES, PARTICULARLY IN THE OPERATION OF FLUID-PRESSURE ENGINES 23/00
TESTING OR CALIBRATING 25/00, 27/00
P:130 G01L 1/00
Measuring force or stress, in general (measuring force due to impact G01L 5/00; measuring fluid pressure G01L 7/00-G01L 27/00; measuring deformation of bodies as a result of stress by using gauges G01B)  [4]
 G01L 1/02
·  by hydraulic or pneumatic means
 G01L 1/04
·  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 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 G01B)
 G01L 1/20
·  by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids (of piezo-resistive materials 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
 G01L 1/25
·  using wave or particle radiation, e.g. X-rays, neutrons (G01L 1/24 takes precedence)  [4]
 G01L 1/26
·  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
P:110 G01L 5/00
Apparatus for, or methods of, measuring force, e.g. due to impact, work, mechanical power, or torque, adapted for special purposes (measuring pressure of a fluent medium G01L 7/00-G01L 21/00; measuring rapid changes of pressure in steam, gas, or liquid G01L 23/00)
 G01L 5/03
·  for measuring release force of ski safety bindings
 G01L 5/04
·  for measuring tension in ropes, cables, wires, threads, belts, bands, or like flexible members
 G01L 5/12
·  for measuring axial thrust in a rotary shaft, e.g. of propulsion plants
 G01L 5/13
·  for measuring the tractive or propulsive power of vehicles
 G01L 5/14
·  for measuring the force of explosions; for measuring the energy of projectiles
 G01L 5/16
·  for measuring several components of force
 G01L 5/18
·  for measuring ratios of force
 G01L 5/20
·  for measuring wheel side-thrust (in balancing G01M)
 G01L 5/22
·  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 B25B 23/14)
 G01L 5/26
·  for determining the characteristic of torque in relation to revolutions per unit of time
 G01L 5/28
·  for testing brakes
 G01L 7/00 - 
G01L 21/00
Measuring fluid pressure
P:70 G01L 7/00
Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements (transmitting or indicating the displacement of mechanical pressure-sensitive elements by electric or magnetic means G01L 9/00; measuring differences of two or more pressure values G01L 13/00; measuring two or more pressure values simultaneously G01L 15/00; measuring tyre pressure or the pressure of other inflated bodies G01L 17/00; vacuum gauges G01L 21/00; hollow bodies deformable or displaceable under internal pressure per se G12B 1/00)
 G01L 7/02
·  in the form of elastically-deformable gauges
P:60 G01L 9/00
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 G01L 13/00; measuring two or more pressure values simultaneously G01L 15/00; vacuum gauges 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
P:80 G01L 11/00
Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L 7/00 or G01L 9/00
P:40 G01L 13/00
Devices or apparatus for measuring differences of two or more fluid pressure values
P:50 G01L 15/00
Devices or apparatus for measuring two or more fluid pressure values simultaneously
P:30 G01L 17/00
Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies (specially adapted for mounting on vehicles or tyres B60C 23/00; connection of valves to inflatable elastic bodies B60C 29/00)
P:90 G01L 19/00
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]