|  | 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

|  | G04G |
ELECTRONIC TIME-PIECES [3]

|  | G04G |
Note(s) This subclass covers: electronic time-pieces with no moving parts; [3] electronic circuitry for producing timing pulses irrespective of the nature of the time-indicating means utilised. [3] This subclass does not cover electronic time-pieces with moving parts, which are covered by subclass Fulltext... Hierarchy... Expanded...G04C. [3]

|  | G04G |
Subclass index
PRODUCING TIMING PULSES | 3/00
TIME-SETTING; SYNCHRONISING | 5/00; 7/00
TIME- OR DATE-INDICATING |
Visual; optical signals; acoustic signals | 9/00; 11/00; 13/00
OPERATING A DEVICE AT PRESELECTED TIMES | 15/00
OTHER SUBJECTS | 1/00

|  | G04G 1/00 |
Subject matter not provided for in groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G04G 3/00-G04G 15/00 [3]

|  | G04G 3/00 |
Producing timing pulses (driving circuits for stepping motors Fulltext... Hierarchy... Expanded...G04C 3/14; producing preselected time intervals for use as timing standards Fulltext... Hierarchy... Expanded...G04F 5/00; pulse technique in general Fulltext... Hierarchy... Expanded...H03K; control, synchronisation, or stabilisation of generators in general Fulltext... Hierarchy... Expanded...H03L) [3]

|  | G04G 3/02 |
· | Circuits for deriving low frequency timing pulses from pulses of higher frequency (pulse frequency dividers in general Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H03K 23/00-H03K 29/00) [3]

|  | G04G 5/00 |
Setting, i.e. correcting or changing, the time-indication [3]

|  | G04G 5/02 |
· | by temporarily changing the number of pulses per unit time, e.g. quick-feed method [3]

|  | G04G 5/04 |
· | by setting each of the displayed values, e.g. date, hour, independently [3]

|  | G04G 7/00 |
Synchronisation [3]

|  | G04G 7/02 |
· | by radio [3]

|  | G04G 9/00 |
Visual time or date indication means [3]

|  | G04G 9/02 |
· | by selecting desired characters out of a number of characters or by selecting indicating elements the position of which represent the time, e.g. by using multiplexing techniques [3]

|  | G04G 9/04 |
· · | by controlling light sources, e.g. electroluminescent diodes [3]

|  | G04G 9/06 |
· · | using light valves, e.g. liquid crystals [3]

|  | G04G 9/08 |
· | by building-up characters using a combination of indicating elements, e.g. by using multiplexing techniques [3]

|  | G04G 9/10 |
· · | by controlling light sources, e.g. electroluminescent diodes [3]

|  | G04G 9/12 |
· · | using light valves, e.g. liquid crystals [3]

|  | G04G 11/00 |
Producing optical signals at preselected times [3]

|  | G04G 13/00 |
Producing acoustic time signals [3]

|  | G04G 13/02 |
· | at preselected times, e.g. alarm clocks [3]

|  | G04G 15/00 |
Time-pieces comprising means to be operated at preselected times or after preselected time intervals (Fulltext... Hierarchy... Expanded...G04G 11/00, Fulltext... Hierarchy... Expanded...G04G 13/00 take precedence; pulse delay circuits Fulltext... Hierarchy... Expanded...H03K 5/13; electronic time-delay switches Fulltext... Hierarchy... Expanded...H03K 17/28; electronic time-programme switches which automatically terminate their operation after the programme is completed Fulltext... Hierarchy... Expanded...H03K 17/296) [3]