|  | G |
SECTION G — PHYSICS

|  | G |
Note(s) 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.

INSTRUMENTS

|  | G04 |
HOROLOGY

|  | G04F |
TIME-INTERVAL MEASURING (measuring pulse characteristics Fulltext... Hierarchy... Expanded...G01R, e.g. Fulltext... Hierarchy... Expanded...G01R 29/02; in radar or like systems Fulltext... Hierarchy... Expanded...G01S; masers Fulltext... Hierarchy... Expanded...H01S 1/00; generation of oscillations Fulltext... Hierarchy... Expanded...H03B; generation or counting of pulses, frequency dividing Fulltext... Hierarchy... Expanded...H03K; analogue/digital conversion in general Fulltext... Hierarchy... Expanded...H03M 1/00) [2]

|  | G04F |
Note(s) This subclass covers: apparatus for measuring-off predetermined time intervals; [2] apparatus for producing such intervals as timing standards, e.g. metronomes; [2] apparatus for measuring unknown intervals, e.g. precision systems for short-time-interval measurement. [2]

|  | G04F |
Subclass index
MEASURING PREDETERMINED TIME INTERVALS |
Producing time standards | 5/00
Apparatus: without driving mechanisms; with driving mechanisms | 1/00; 3/00
MEASURING UNKNOWN TIME INTERVALS |
Mechanically; electromechanically; electrically; otherwise | 7/00; 8/00; 10/00; 13/00

P:20 |  | G04F 1/00 |
Apparatus which can be set and started to measure-off predetermined or adjustably-fixed time intervals without driving mechanisms, e.g. egg timer (time or time-programme switches which automatically terminate their operation after the programme is completed Fulltext... Hierarchy... Expanded...H01H 43/00)

|  | G04F 1/02 |
· | by consuming prefixed quantities of materials, e.g. by burning candle

|  | G04F 1/04 |
· | by movement or acceleration due to gravity

|  | G04F 1/06 |
· · | by flowing-away of a prefixed quantity of fine-granular or liquid materials, e.g. sand-glass, water-clock

|  | G04F 1/08 |
· · | by a body falling a prefixed distance in air or in a viscous material

P:10 |  | G04F 3/00 |
Apparatus which can be set and started to measure-off predetermined or adjustably-fixed time intervals with driving mechanisms, e.g. dosimeter with clockwork (time or time-programme switches which automatically terminate their operation after the programme is completed Fulltext... Hierarchy... Expanded...H01H 43/00)

|  | G04F 3/02 |
· | with mechanical driving mechanisms

|  | G04F 3/04 |
· · | Additional arrangements in connection with ordinary non-electric clocks for this purpose

|  | G04F 3/06 |
· | with electric driving mechanisms

|  | G04F 3/08 |
· · | Additional arrangements in connection with ordinary electric clocks for this purpose

P:0 |  | G04F 5/00 |
Apparatus for producing preselected time intervals for use as timing standards (generating clock signals for electric digital computers Fulltext... Hierarchy... Expanded...G06F 1/04; automatic frequency control or stabilisation of generators in general Fulltext... Hierarchy... Expanded...H03L)

|  | G04F 5/02 |
· | Metronomes

|  | G04F 5/04 |
· | using oscillators with electromechanical resonators [2]

|  | G04F 5/06 |
· · | using piezo-electric resonators [2]

|  | G04F 5/08 |
· · | using magnetostrictive resonators [2]

|  | G04F 5/10 |
· | using electric or electronic resonators (Fulltext... Hierarchy... Expanded...G04F 5/14 takes precedence) [2]

|  | G04F 5/12 |
· | using fluidic devices [2]

|  | G04F 5/14 |
· | using atomic clocks [2]

|  | G04F 5/16 |
· | using pulses produced by radio-isotopes [2]

P:50 |  | G04F 7/00 |
Apparatus for measuring unknown time intervals by non-electric means (Fulltext... Hierarchy... Expanded...G04F 13/06 takes precedence) [2]

|  | G04F 7/02 |
· | by measuring the distance of fall or the final velocity of a falling body

|  | G04F 7/04 |
· | using a mechanical oscillator [2]

|  | G04F 7/06 |
· · | running only during the time interval to be measured, e.g. stop-watch

|  | G04F 7/08 |
· · | Watches or clocks with stop devices, e.g. chronograph

|  | G04F 7/10 |
· | Means used apart from the time-piece for starting or stopping same [2]

P:30 |  | G04F 8/00 |
Apparatus for measuring unknown time intervals by electromechanical means [2]

|  | G04F 8/02 |
· | using an electromechanical oscillator [2]

|  | G04F 8/04 |
· · | using a piezo-electric oscillator [2]

|  | G04F 8/06 |
· · | using a magnetostrictive oscillator [2]

|  | G04F 8/08 |
· | Means used apart from the time-piece for starting or stopping same [2]

P:40 |  | G04F 10/00 |
Apparatus for measuring unknown time intervals by electric means [2]

|  | G04F 10/02 |
· | using oscillators with passive electric resonator, e.g. lumped LC [2]

|  | G04F 10/04 |
· | by counting pulses or half-cycles of an ac [2]

|  | G04F 10/06 |
· | by measuring phase [2]

|  | G04F 10/08 |
· | using pulses produced by radio-isotopes [2]

|  | G04F 10/10 |
· | by measuring electric or magnetic quantities changing in proportion to time [2]

P:60 |  | G04F 13/00 |
Apparatus for measuring unknown time intervals by means not provided for in groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G04F 5/00-G04F 10/00 [2]

|  | G04F 13/02 |
· | using optical means [2]

|  | G04F 13/04 |
· | using electrochemical means [2]

|  | G04F 13/06 |
· | using fluidic means [2]