GB2206208A

GB2206208A - Measuring device

Info

Publication number: GB2206208A
Application number: GB08715091A
Authority: GB
Inventors: Nigel Reid-Foster
Original assignee: REID FOSTER NIGEL
Current assignee: REID FOSTER NIGEL
Priority date: 1987-06-26
Filing date: 1987-06-26
Publication date: 1988-12-29
Also published as: GB8715091D0

Abstract

A device is described which is able to measure a length and automatically divide the measured length into distances proportional to the total length. The device consists of two retractable measuring tapes (18, 20) which are coupled together in a unit (12) via a set of gears (26) having a variety of pre-set ratios. The gear ratio can be set to a specific value and when one tape is extended the gear ratio causes the other tape (20, 18) to be extended automatically in the opposite direction in accordance with the set gear ratio. <IMAGE>

Description

MEASURING DEVICE The present invention relates, particularly, but not exclusively, to a measuring device which provides an automatic indication of proportional division of a measured or certain length.

In many situations it is desirable to be able to measure a length and to be able to automatically divide the measured length into distances proportional to the total length. For example, in photography it is useful to know the relative distances between objects in a field of view so that the depth of field, and of an image,can be set for proper focus control. Distance measuring between two points can be conveniently carried out by using a retractable measuring tape.

However, it is often slow and inconvenient to calculate and mark divisions of distance between the two points and such existing devices are not readily useable for such a purpose.

An object of the present invention is to provide an improved device which obviates or mitigates the aforesaid disadvantages.

This is achieved by providing a device consisting of two retractable measuring tapes which are coupled together in a unit via a set of gears having a variety of pre-set ratios. The gear ratio can be set to a specific value and when one tape is extended the gear ratio causes the other tape to be extended automatically in accordance with the set ratio.

In a preferred arrangement the measuring tapes are identical and coupled to a coma gear unit in a single housing which has openings to permit the tape measures to extend, in use, in opposite directions.

A variety of selectable gear ratios can be provided to provide flexibility in providing proportional measurement.

According to one aspect of the present invention there is provided proportional measuring apparatus comprising first tape distance measuring means having a first measuring tape adapted to be unwound in a first direction, second tape distance measuring means having a second measuring tape adapted to be unwound in a second direction opposite said first direction, said first and said second tape distance measuring means being coupled via gearing means, said gearing means having at least one gear ratio whereby, in use, when one of said first and said second tapes are extended from said apparatus in one direction the other tape is automatically extended from said apparatus in the opposite direction by an amount corresponding to said gear ratio.

Preferably said gearing means comprises a plurality of gear ratios, and each of said gear ratios being selectable by the user.

Conveniently, said first and said second tape measuring means and said gearing means are disposed in a common housing, said housing having respective apertures to permit said first and said second tapes to extend therefrom in opposite directions.

Conveniently, the term tape includes any other suitable flexible measuring means which can be wound and unwound, such as rope, string, wire and the like. b These and other aspects of the invention will become apparent from the following description when taken in combination with the accompanying drawing which is a diagrammatic view of measuring apparatus in accordance with an embodiment of the invention.

Reference is now made to the drawing which depicts a proportional measuring apparatus 10 having a generally rectangular housing 12 which contains first and second rotary mounted tape devices 14,16 which carry respective measuring tapes 18,20. The housing has apertures 22,24 through which tapes 16,18 respectively pass. It will be appreciated that devices 14,16 are mounted so that unwinding of the tapes 18,20, as will be described, cause the tapes to extend in opposite directions. The rotary mounted tape devices 14,16 are coupled together by a gearbox 26 which contains a set of gears (not shown).

The gearbox is coupled to a gear ratio selecter 28 which extends outside the housing and which can be set to a specific ratio for example, 1/2, 1/3 This means that if the ratio is 1/3 tape 18 is unwound by a distance of 2 feet will cause the other tape 20 to extend to a distance of 1 foot giving a total length of 3 feet with a division at 1/3 given by the centre 30 of the housing 12.

It will be understood that various modifications may be made to the apparatus as described, for example, the divisions can be made as required using various combinations of gear ratios. The actual gearing is not part of the invention and any suitable gearing arrangement evident to a man of ordinary skill in the art can be used.

Claims

CLAIMS:

1. Proportional measuring apparatus comprising first tape distance measuring means having a first measuring tape adapted to be unwound in a first direction, second tape distance measuring means having a second measuring tape adapted to be unwound in a second direction opposite said first direction, said first and said second tape distance measuring means being coupled via gearing means, said gearing means having at least one gear ratio whereby, in use, when one of said first and said second tapes are extended from said apparatus in one direction the other tape is automatically extended from said apparatus in the opposite direction by an amount corresponding to said gear ratio.

2. Apparatus as claimed in claim 1 wherein said gearing means comprises a plurality of gear ratios, and each of said gear ratios being selectable by the user.

3. Apparatus as claimed in claim 1 or claim 2 wherein said first and said second tape measuring means and said gearing means are disposed in a common housing, said housing having respective apertures to permit said first and said second tapes to extend therefrom in opposite directions.

4. Apparatus as claimed in any one of claims 1 to 3 wherein the term tape includes any other suitable flexible measuring means which can be wound and unwound, such as rope, string, wire and the like.