GB2217657A

GB2217657A - Figure generating device

Info

Publication number: GB2217657A
Application number: GB8809618A
Authority: GB
Inventors: Howard Rowe
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-04-22
Filing date: 1988-04-22
Publication date: 1989-11-01
Also published as: GB8809618D0

Abstract

A device for generating an ellipse is made up of a body member 10 providing first 12 and second 13 straight paths intersecting at their centres. Carriers 14, 15 are provided for sliding along each path. The carriers are demountably linked by a bridge 18 on which is mounted a generating head 20 mounted on the working lengths or an extension thereof and adapted to output as a locus movement of the generating head in response to the passage of at least one of the carriers along its respective path to describe an ellipse. The generating head can incorporate a marking device such as a pen or directly or indirectly operate a machine tool. In another embodiment (See figure 3) the first and second paths are provided on separate parallel members disposed one above the other. <IMAGE>

Description

FIGURE GENERATING DEVICE This invention relates to a figure generating device and in particular is concerned with the generation of a conic section.

A general definition of a conic section is that it is the locus of a point which moves so that its distance from a given point is a constant ratio to its perpendicular distance from a given straight line. If the ratio is less than unity then the locus is in the form of an ellipse.

Conic sections in general and ellipses in particular can be displayed and plotted with varying degrees of success using a computer. however the ability to readily generate an ellipse without the need for expensive equipment would be useful in a variety of contexts including drawing and machining.

According to the present invention there is provided a device for generating an ellipse comprising: a) a body which defines first and second straight paths either by: 1) a main plate like member wherein the paths lie in a common plane in the form of a cross intersecting at their centres; or 2) first and second plate like members providing, respectively, the first and second paths, the first and second members having their planes parallel and the paths, in plan view, being disposed in the form of a cross with the midpoint of the lengths of the paths lying on a common axis; b) first and second carriers disposed for sliding along, respectively, the first and second paths; c) a bridge adapted for demountable coupling to the carriers to define between the first and second carriers a working length of the bridge; and d) a generating head mounted on the working length or an extension thereof and adapted to output as a locus movement of the generating head in response to the passage of at least one of the carriers along its respective path.

In a first preferred form of the present invention the main member is a single plate and the first and second paths are defined by slots in the plate.

In a second preferred form of the present invention the body is of first and second menibers each made up of a plate, the plates being mounted one above the other and adapted for rotation relative to one another about a common central axis; the first plate defining the first path by way of a first slot; the second plate serving to define the second path by way of a second slot; the bridge member being positioned between the plates.

In a third preferred from of the present invention or the first or second preferred forms thereof the carriers are in the for#r: of travellers adapted for tow friction motion along the paths.# In a fourth preferred form of the present invention or any preferred form thereof the generating head incorporates a marking device, such as a pen, so as to deposit a trade of the locus on recording material juxtaposed with the body.

Alternatively the generating head incorporates or is adapted @@@ guicte a loop such - maschine tool for cutting.

In an alternative farnr of the present invention the mstn member or the first and second members are forn#ed by a frame and the first and second paths are each formed by a path member incorporated in the frame; and the carriers are in the form of riders slidaby retained on their respective path members.

Exemplary embodiments of the invention will now be described with reference to the accompanying drawing of which: Figure 1 is a plan view (seen from beneath) of a first embodiment of an ellipse drawing engine; Figure 2 is a side view of the device shown in Figure 1; and Figure 3 is an exploded perspective view of a second embodiment.

Referring now to Figures 1 and 2.

Plate 10, of transparent plastics material, is mounted on legs 11 and has paths 12, 13 cut through it in the form of a right angled cross with intersection X. Each path is of length L.

Carriers 14, 15 of 11section are located for sliding movement in, respectively, paths 12, 13. The carrier 14 has a central passage through which extends a bolt 16.

The carriers 14, 15 are coupled by a bridge 18 which has a central slot 19 through which bolt 16, and a corresponding bolt 17 for carrier 15, extends to enable the carriers to be secured to the bridge 18 at a selected spacing S. When secured on spacing S the carriers 14, 15 can still rotate relative to the bridge 18. Bolts 16 and 17 extend upwardly above plate 10 and are coupled by means of a handle 22. The handle 22 has an interior bore to receive the portion of bolt 17 extending above the plate 10 and a slot to receive the extending part of bolt 16. The slot allows movement of the bolt 16 to move towards and away from the bolt 17 in the course of drawing. The carrier 15 is fixed in position as to the length of the bridge 18 while allowing rotation of the carrier 15 relative to the bridge.

The region of the bridge included by spacing S is termed the 'working length' and governs in part the size of the ellipse to be generated. The working length has mounted in it a generating head 20 which has projecting from it a plotting pen 21 which inscribes on a worksheet P the locus of the generating head when it moves. The head 20 is mounted to slide on the outer edges of the bridge 18 and can be positioned and clamped at any point along the length of the bridge 18 without being impeded by the location of the carriers which are located by way of the slot 19. The head can be clamped at a point within working length S or on the outer part of the bridge beyond the carriers 14, 15 to increase the size of the ellipse to be drawn.

In use the plate engine is located over worksheet P by way of legs 11 with the carriers 14, 15 and the generating head 20 locked to the bridge 18 at positions governed by the characteristics of the ellipse to be drawn. Carrier 14, is then locked in place in its path 12. The pen 21 is then lowered into contact with the worksheet P. Thereafter handle 22 is grasped and rotated to displace bolt 16 along the path 12 and also to cause movement of bolt 16 relative to the bolt 17.

The motion imparted by way of the handle 22 to the bolts 16, 17 causes their respective carriers 14, 15 to move along their respective tracks 12, 13. As a consequence of the carrier movement the bridge member 18 is moved to cause the head 20, and so pen 21, to move on a locus governed by the sliding movement of carriers along their paths. The resulting figure traced by the pen 21 on the worksheet P is an ellipse.

The size and relative proportions of the ellipse generated is dependent on spacing S and the distance T between carrier 15 and head 20. It will be apparent that T can be greater than S when the head is located towards the outer ends of bridge 18.

While the head 20 is shown in this embodiment with a plotting pen 21 the pen can be replaced by a machine tool such as a milling cutter or an engraver.

The embodiment has paths 12, 13 disposed at right angles.

Referring now to Figure 3, in which the parts are shown separated from one another to aid viewing, there is provided an embodiment wherein the paths besides being capable of being positioned at right angles can be positioned at any selected angle to generate alternative ellipse projections.

In Figure 3 the body 30 is made up of two transparent plates 31, 32 retained in the form of a drum by side 33. The side incorporates legs L whereby the engine can be mounted on a paper surface S on which an ellipse is to be drawn.

The side 33 serves to retain plate 32 fixed while allowing plate 31 to be rotated about axis A relative to the plate 32.

Plate 31 incorporates a slot 34 which slidaby retains carrier 35. Plate 32 incorporates a slot 36 which slidably retains carrier 37.

Bridge member 38 is positioned between the plates 31, 32 being pivotably coupled to, respectively, carriers 35, 37. Coupling is by way of bolt 39 to carrier 35 and bolt 40 to carrier 37.

As was the case with carrier 15 in Figure 1 carrier 37 in Figure 3 is fixed as to it relative position along the bridge 38 while allowing relative rotation between carrier and bridge.

Generating head 41 (incorporating a pen 42) is mounted on extension 43 of bridge 38 to which the extension 43 is connected by way of bolt 40. The connection between extension 43 and bridge 38 ensures that no relative movement occurs between them in use The size of the ellipse drawn by the engine is governed by lateral spacing P between bolts 39 and 40 and lateral spacing Q between bolt 40 and head 41.

In use the spacings P and Q are selected and the carrier 37 is fixed relative to slot 36. The engine is then placed on surface S and pen 41 extended to contact surface s. Carrier 35 is then displaced along its slot 34 to cause bridge 38 to be displaced and rotated, likewise extension 43, an ellipse to be traced out by the pen 41.

Claims

1 A device for generating an ellipse comprising: a) a body which defines first arid second straight paths either by: I) a main plate like member wherein the paths lie in a common plane in the form of a cross intersecting at their centres; or 2) first and second plate like members providing, respectively, the first and second paths, the first and second members having their planes parallel and the paths, in plan view, being disposed in the form of a cross with the midpoint of the lengths of the paths lying on a common axis; b) first and second carriers disposed for sliding along, respectively, the first and second paths; c) a bridge adapted for demountable coupling to the carriers to define between the first and second carriers a working length of the bridge; and d) a generating head mounted on the working length or an extension thereof and adapted to output as a locus movement of the generating head in response to the passage of at least one of the carriers along its respective path.

2 A device as claimed in Claim 1 wherein the main member is a single plate and the first and second paths are defined by slots in the plate.

3 A device as claimed in Claim 1 wherein the body is of first and second members mounted one above the other for rotation about a common central axis; the first plate serving to define the first path; the second plate serving to define the second path; the bridge member being positioned between the plates

4 A device as claimed in any preceding claim wherein the carriers are in the form of travellers adapted for low friction motion along the paths.

5 A device as claimed in any preceding claim wherein the generating head incorporates a marking device, such as a pen, so as to deposit a trace of the locus on recording material juxtaposed with the body.

6 A device as claimed in any of preceding claims 1 to 4 wherein the generating head incorporates or is adapted to guide a tool such as a machine tool for cutting.

7 A device as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.