GB2269015A

GB2269015A - Apparatus for determining distances or dimensions

Info

Publication number: GB2269015A
Application number: GB9215471A
Authority: GB
Inventors: Ian Francis Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-07-21
Filing date: 1992-07-21
Publication date: 1994-01-26
Anticipated expiration: 2012-07-21
Also published as: GB9215471D0; GB2269015B

Abstract

An apparatus for determining the distance of a relatively distant object 10 having a known dimension from an observer, or alternatively for determining the dimension of such an object the distance to which is known, has an elongate base member 1 carrying a fixed back-sight 2 and a moveable fore-sight 3 which has a pair of indicators 8 having separation "w" transverse to the line of sight. The user views the distant object 10 via the rear-sight and the fore-sight and moves the fore-sight so that the pair of indicators 8 precisely frames the dimension (h2) of the distant object, whereupon a scale reading is then taken and either the known dimension or distance is multiplied by the reading to calculate the unknown distance respectively. <IMAGE>

Description

APPARATUS FOR DETERMINING DISTANCES OR DIMENSIONS This invention relates to an apparatus for determining distances or dimensions.

It is known that when a first relatively close object exactly eclipses a second relatively distant object 02 along an observer's line of sight, corresponding dimensions h1 and h2, transverse to the line of sight, of the two objects O and 02 respectively are related to the distances d1 and d2 of the objects O and O2 respectively from the observer by the equation: h1d2 = h2d1 (I).

According to a first aspect of the present invention, there is provided an apparatus for determining the distance (d2) of a relatively distant object (02) from an observer, being an object having a known dimension (h2) transverse to the line of sight of the observer, the apparatus including an elongate base member carrying a fixed back-sight and a moveable fore-sight, which constitutes an object ( 1) of much lesser distance (d1) from the observer than the unknown distance (d2) and which has a pair of indicators defining therebetween a known separation (h1) transverse to the line of sight, the fore-sight being moveable along the base member in the direction along the line of sight, and the apparatus further including means for computing the ratio of a selected distance between (dl) between the fore-sight and the observer to the known separation (h1), whereby upon viewing the distant object via the rear-sight and the fore-sight and moving the fore-sight so that the pair of indicators precisely frames the known dimension (h2) of the distant object, the unknown distance (d2) can be determined from the ratio (dl:hl) by taking into account the value of the known dimension (h2) of the distant object and having regard to equation I above.

The determination of the unknown distance may be performed by the observer as a multiplication of the ratio by the known dimension, or by calculating means associated for this purpose with the apparatus.

Of course, where the range (d2) of the distant object is known, but its dimension (h2) needs to be determined, the apparatus of the invention can be used for this purpose with no or minimal modification. Using the apparatus in the same way as described above, h2 can readily be determined by dividing d2 by the ratio dl:hl. This alternative use or variation constitutes a second aspect of the present invention.

The ratio-computing means may suitably be mechanical, electrical or electromechanical and the calculating means for determination of the unknown distance or dimension may, when present, suitably be electrical. Preferably the ratio-computing means includes a linear scale extending parallel to the line of sight over the range of movement of the fore-sight and a set of scale markings associated therewith, the set marking at intervals along the scale length the appropriate ratio for the position on the scale (which corresponds to do). Thus, the location of the fore-sight when the distant object is precisely framed by the indicators thereof indicates the ratio (dl:hl) by which the known parameter (h2 or d2) of the distant object is to be multiplied or divided to determine the unknown parameter.The linear scale can suitably extend on the base member from the back-sight substantially the entire length of the base member.

To extend the range of the apparatus, the fore-sight can have one or more additional pairs of indicators. Where the fore-sight has more than one pair of indicators the separations transverse to the line of sight defined by two of the pairs can be at right angles to one another.

Each pair may preferably define therebetween a different known separation (h1). In this event, a corresponding number of sets of scale markings are suitably provided on the base as ratio-computing means, each set appropriately calibrated to one of the separations h1.

There can be provision for locking the fore-sight to the base member in its adjusted position.

The fore-sight can carry a vernier scale co-operating with the linear scale, for greater accuracy of reading the scale.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a schematic side view of an apparatus for determining distances or dimensions, Figure 2 shows, on a larger scale, a fore-sight of the apparatus of Figure 1 as seen by a user of the apparatus, and Figure 3 shows, also on a larger scale, an alternative form of fore-sight.

The apparatus of Figure 1 is for determining the distance of a relatively distant object from an observer, being an object having a dimension transverse to the line of sight of the observer that is either known or can be estimated accurately and so effectively is known, or alternatively for determining a dimension of a relatively distant object, the distance (range) of which is either known (e.g. from a map) or can be estimated accurately and so effectively is known.

The apparatus includes a base member 1 having secured fast to it at one end a fixed back-sight 2. The base member 1 also carries a moveable fore-sight 3 mounted on a carrier 4 which is slidable along the base member 1.

In order that the carrier 4 maintains any position to which it is adjusted it is either operated to move along the base member 1 by a screw mechanism having an actuator wheel 5, or the carrier incorporates a clamp mechanism (not shown) which can be released to permit movement of the carrier and then locked to clamp the carrier to the base member.

To facilitate steady holding of the apparatus by the user there is a cheek rest 6 at the back-sight end of the base member 1 and a hand grip 7 near the other end of the base member. A forehead-rest (not shown) may be provided if desired.

As shown in Figure 2, the fore-sight 3 has a pair of indicators 8,8 which define between them a known fixed separation transverse to the line of sight of the user, indicated in Figure 2 at w.

Along the base member 1, and hence extending along the line of sight of the user, there is a linear scale 9 extending from the fixed back-sight 2.

The apparatus utilises the principle that when a first relatively close object O exactly eclipses a second relatively distant object 02 along an observers line of sight, corresponding dimensions h1 and h2 transverse to the line of sight of the two objects O and 02 respectively are related to the distances d1 and d2 of the objects 0i and 02 respectively from the observer by the equation: hld2 = h2d1 (I).

In use of the apparatus the moveable fore-sight 3 constitutes the relatively close object O and in Figure 2 there is indicated for example a church 10 constituting the relatively distant object 02, the known (or reasonably accurately estimateable) height of the spire of which constitutes the dimension h2. The known separation w defined between the pair of indicators 8,8 constitutes the dimension h1. The user observes the church 10 both through a circular aperture 11 provided in the back-sight 2 and through the fore-sight 3 and moves the fore-sight 3 along the base member 1 until, as illustrated in Figure 2, the spire is exactly framed between the indicators 8,8. The distance of the foresight 3 from the back-sight 2 is now distance d1.

The scale 9 is marked at intervals along its length with the value of the ratio d1:hl appropriate for the particular location on the scale, to enable the observer to determine, from reading the scale at the point immediately adjacent the fore-sight 3, the distance d2 from him of the distant object 02. The scale indicates the factor by which the known dimension h2 has to be multiplied to determine the distance d2. A vernier scale 12 is provided on the carrier 4, for greater accuracy of reading the linear scale 9. Where, alternatively, the distance d2 of the church 10 is known, e.g. from a map, the height of the spire (h2) is in that event determined by dividing the known distance d2 by the ratio indicated by the scale markings.

The modified form of fore-sight shown in Figure 3 has three pairs of indicators 8:, 8:; 8y,8Z; 8:, 8: respectively defining between them two alternative vertical separations x and y and one horizontal separation z.

This fore-sight enables the range of the apparatus to be extended by utilising three different sets of scale markings (not shown), respectively related to the separations x, y and z, the user selecting the appropriate scale for the separation used to frame the distant object.

The apparatus may, with any necessary scale, sight or other adjustments which will be readily apparent to those skilled in this art, be used for determining the distance from an observer to almost any distant object having one known or estimatable dimension, including for example, buildings, architectural features, bridges, hills, trees, people, animals, golf-flags, vehicles and ships. As indicated above, the apparatus can alternatively be used with no or minimal modification, for determining the dimensions of a distant object where its range is accurately known (e.g. from a map).

The foregoing broadly describes the invention without limitation. Variations and modifications as will be readily apparent to those skilled in this art are intended to be included in the scope hereof.

Claims

1. An apparatus for determining the distance (d2) of a relatively distant object (02) from an observer, being an object having a known dimension (h2) transverse to the line of sight of the observer, the apparatus including an elongate base member carrying a fixed back-sight and a moveable fore-sight, which constitutes an object ( 1) of much lesser distance (d1) from the observer than the unknown distance (d2) and which has a pair of indicators defining therebetween a known separation (h1) transverse to the line of sight, the fore-sight being moveable along the base member in the direction along the'line of sight, and the apparatus further including means for computing the ratio of a selected distance between (d1) between the fore-sight and the observer to the known separation (he), whereby upon viewing the distant object via the rearsight and the fore-sight and moving the fore-sight so that the pair of indicators precisely frames the known dimension (h2) of the distant object, the unknown distance (d2) can be determined from the ratio (d1:hl) by taking into account the value of the known dimension (h2) of the distant object and having regard to the following equation:: h1d2 = h2d1 (I) where h1 is the known separation of the fore-sight, h2 is the known dimension of the relatively distant object, d1 is the distance of the fore-sight from the observer, and d2 is the unknown distance of the relatively distant object from the observer.

2. An apparatus for determining a dimension (h2) of an object (02) which is of known relatively large distance (d2) from an observer, the unknown dimension (h2) being transverse to the line of sight of the observer, the apparatus including an elongate base member carrying a fixed back-sight and a moveable fore-sight, which constitutes an object ( 1) of much lesser distance (dl) from the observer than the known distance (d2) and which has a pair of indicators defining therebetween a known separation (h1) transverse to the line of sight, the fore-sight being moveable along the base member in the direction along the line of sight, and the apparatus further including means for computing the ratio of a selected distance (dl) between the fore-sight and the observer to the known separation (he), whereby upon viewing the distant object via the rear-sight and the fore-sight and moving the fore-sight so that the pair of indicators precisely frames the unknown dimension (h2) of the distant object, the unknown dimension (h2) can be determined from the ratio (dl:hl) by taking into account the value of the known distance (d2) of the distant object and having regard to the following equation:: h1d2 = h2dl (I) where h1 is the known separation of the fore-sight, h2 is the unknown dimension of the relatively distant object, d1 is the distance of the fore-sight from the observer, and d2 is the known distance of the relatively distant object from the observer.

3. An apparatus according to claim 1 or 2, in which the ratio-computing means comprises a linear scale extending parallel to the line of sight over the range of movement of the fore-sight and a set of scale markings associated therewith, the set marking at intervals along the scale length the appropriate ratio (d1:hl) for the position on the scale (which corresponds to d1).

4. An apparatus according to any preceding claim, in which the fore-sight has one or more additional pairs of indicators.

5. An apparatus according to claim 4, in which the separations transverse to the line of sight defined by two of the pairs of indicators are at right angles to one another.

6. An apparatus according to claim 4 or 5, in which each pair of indicators defines therebetween a different known separation (h1).

7. An apparatus according to claim 6, in which the ratio-computing means comprise a corresponding number of sets of -scale markings associated with a linear scale extending parallel to the line of sight over the range of movement of the fore-sight, and each set marking at intervals along the scale length the appropriate ratio (d1:hl) for the position on the scale (which corresponds to dl), calibrated to one of the dimensions (h1).

8. An apparatus according to claim 3 or 7, in which the fore-sight carries a vernier scale co-operating with the linear scale.

9. An apparatus for determining the distance or dimension of a relatively distant object, substantially as herein described with reference to Figs. 1 and 2 of the accompanying drawings.

10. An apparatus for determining the distance or dimension of a relatively distant object, substantially as herein described with reference to Figs. 1 and 3 of the accompanying drawings.