AU619396B2

AU619396B2 - Ellipsograph compass

Info

Publication number: AU619396B2
Application number: AU52388/90A
Authority: AU
Inventors: Khalil Abdallah
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-08-23
Filing date: 1990-03-29
Publication date: 1992-01-23
Anticipated expiration: 2009-08-23
Also published as: AU5238890A

Description

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-I I COMMONWEALTH OF AUSTRALI 9 3 9 PATENTS ACT 1952 Form COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: *5*S 0 0SS*

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TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: KHALIL ABDALLAH 7 Station Street, Guildford, New South Wales, 2161, Australia KHALIL ABDALLAH GRIFFITH HACK CO 71 YORK STREET SYDNEY NSW 2000

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*0 Complete Specification for the invention entitled: ELLIPSOGRAPH COMPASS The following statement is a full description of this invention, including the best method of performing it known to me/us:- GH REF P21128B/COS 6610A/EM j 2 This invention concerns an ellipsograph, that is a drawing instrument used for drawing ellipses.

A number of ellipsographs are known, and these typically comprise a stand and a complicated arrangement of rotating levers or gears which operate to constrain a scriber to move with an ellipsical locus. The known devices are characterised by being complicated, cumbersome and difficult to use.

According to the present invention, there is provided an ellipsograph, comprising: a supp-. L means comprising a vertical column; a circular guide means attached to the support means

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and rotatable about its origin, the circular guide means also being pivotably adjustable about a horizontal axis colinear 3 with one of its diameters to project an ellipse having the relative lengths of its major and minor axes variable depending on the degree of adjustment, onto a horizontal surface; and a vertical describing means supported by the vertical column such that it is able to remain vertical and move towards, away from and around the vertical column, the 0: vertical describing means also being linked to the circular guide means so that it is constrained to describe a r*0" horizontal ellipse having the same relative lengths of major •I4 25 and minor axes as the projected ellipse, as the circular guide means is rotated about its origin.

It should be appreciated that where the terms "vertical" and "horizontal" have been used throughout this description and the appended claim, they are intended only jkl^/ -3r i to be construed relatively, and not to imply any alignment with any external frame of reference.

Preferably, the circular guide means comprise a pair of coplanar, concentric rings which cre rotatable with respect to each other about an axis through their common origin and perpendicular to their common plane. In order to achieve this, an annular space separating the two rings may be packed with hall bearings. In this arrangement, the describing means may conveniently be attached to the outer ring, and the inner ring may be pivotally mounted to the V support means by means of a pin which passes along a diameter of that ring. Locking means are associated with the inner ring and support means to lock the pin into any desired angle of rotation from the horizontal. Both rings are rotated OV 0.: 15 about the pin in order to project an ellipse onto a horizontal surface.

A pen holder is preferably attached to the describing means. In use, a pen may be releasably inserted into the holder.

In a preferred embodiment of the invention, a pantographic structure may be connected between the describing means and a pen holder to enable ellipses of different sizes to be drawn.

Advantageously, a number of horizontal rods may interconnect the vertical column and the pantograph in a slidable fashion to support the pantograph, and allow it to slide radially inwards and outwards with respect to the column.

4 T -4- In order to draw an ellipse using an ellipsograph according to a preferred embodiment of the present invention it is necessary: to attach a pen to the describing means; to set and fix the angle of the circular guide means with respect to the vertical in order to define the ratio between the major and minor axes of the ellipse; to set and fix the pantograph to determine the size of the ellipse to be drawn; l0 to hold the support column vertically with respect to the horizontal surface onto which the ellipse is to be drawn; and to rotate the circular guide means about its origin.

In embodiments which employ a central support column, 15 this merely involves manipulating the ellipsograph in the same manner as a pair of compasses are operated.

The invention enjoys a number of advantages such as being simple to set up and use. The device is also substantially planar which is convenient for packing away flat after use, and saves dissembling the device when not in use.

An ellipsograph embodying the present invention will now be described by way of example only with reference to the accompanying drawings, in which: 'S:21128B s:21 1 28 figure 1 is a perspective view of an ellipsograph embodying the present invention; figure 2 is a vertical sectional view (semi-schematic) through the ellipsograph of figure 1; figure 3 is a schematic view of the ellipsograph of figure 1; figure 4 is a schematic view of the ellipsograph of figure 3 in a second configuration; and figure 5 is a schematic view of the ellipsograph of figure 3 in a third configuration.

The same reference numerals have been used throughout the drawings to refer to corresponding elements.

Referring now to Figure 1, ellipsograph 1 comprises a S. vertical support column 2 on which is mounted a circular 15 guide means 3 comprising inner 4 and outer 5 concentric, circular rings. A describing means 6 is connected to outer ring 5. and a pen 7 is connected to describing means 6 by a pantograph arrangement indicated generally at 8.

Inner 4 and outer rings 5 are separated by an annular space packed with ball bearings 9 so that the two rings can rotate with respect to each other about the common axis which passes through their origins normal to the plane in which they both lie.

Inner ring 4 has a diametrically extending slot 10 in its interior which allows it to rotate about a horizontal axis 11 which extends along the diameter perpendicular to the slot. A pin (not shown) passes along axis 11 and through support column 2 and mounts the circular guide means 3 to column 2 in a manner that enables it to rotate about horizontal axis 11 and project an ellipse onto the horizontal surface at the bottom of column 2.

The angle c which circular guide means 3 makes with respect to the horizontal is governed by a system of links 12 (shown only in Figure 2) associated with guide means 3, and extending through the interior of column 2 to a knurled knob 13 at the top of the column. The system of links 12 connects to the inner ring 4 by means of a worm gear 14 associated with the pin which passes along axis 11i.

Rotation of knob 13 causes the pin, and guide means 3, to be rotated, thus adjusting angle a. The system of links 12 prevents rotation of guide means 3 about axis 11 other than by rotating knob 13.

The describing means indicated generally at 6 is connected to the circular guide means 3 in the following way: a block 15 is rigidly attached to the exterior of outer ring 5. This block is rotatably connected to a U-shaped member 16 by means of a pin 17 extending in a radial direction with respect to the circular guide means.

U-shaped member 16 is rotatably connected to a socket 18 by means of a horizontal pin 19 passing between the ends of the

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o o 15 A first vertical member 20 is slidably mounted inside socket 18. As outer ring 5 rotates about inner ring 4, S• U-shaped member 16 rotates with respect to block 15 about .i pin 17, and socket 18 rotates with respect to U-shaped member 16 about pin 19 to allow first vertical member 20 to to remain vertical at all times.

Near the upper and lower ends of first vertical member 20 there are attached respective pairs of o horizontally extending rods, 21 and 22. Rods 21 and 22 make slidable engagement with respective sockets 23 and 24 which are rotatably associated with column 2. Rods 21 and 22 serve to maintain first vertical member 20 vertical at all

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times as it travels around column 2, and these rods slide in and out of socket 23 and 24 as member 20 moves away from and towards column 2. Pen 7 associated with first vertical :30 member 20 will describe an ellipse as outer ring 5 rotates so about inner ring 4.

The ellipse that is defined by pen 7 has a major axis equal to twice the radial distance of pen 7 from the centre of column 2, and a minor axis equal to this amount multiplied by cosine a.

A second vertical member 25 is connected to and spaced apart from first member 20 by means of upper and Y j4 L,11(4L EM- N~q lower parallel diagonal members 26 and 27 respectively. The connections between the four members. 20, 25, 26 and 27 are pivotal and they form an adjustable parallelogram. The distal end of upper member 26 is attached to a collar 28 which is rotatably mounted on column 2. The vertical height of the attachment is governed by means of an internal linkage arrangement 29 which is controlled by a second knurled wheel 30. The shear angle of the parallelogram may be varied by rotating wheel 30 and moving the point of attachment of diagonal member 26 vertically on collar 28.

The portion of diagonal member 26 joining the parallelogram to column 2 must be telescopic to enable this to occur. The shear angle of the parallelogram can be fixed by means of grub screws associated with the rotatable connections between members 20, 25, 26 and 27.

A third knurled wheel 31 is coupled to the top of S. collar 28 to control the rotation of the device 1 about its 0 vertical axis.

The lower diagonal member 27 extends away from column 2 and its distal end is rotatably connected to pen holder 32 by means of a horizontal pin 33 which permits pen holder 32 to remain vertical at all shear angles of the o parallelogram. A further pair of parallel rods 34 slidably interconnect pen holder 34 and column 2 to ensure pen 7 remains vertical during use. Rods 34 are fixed to column 2 by means of a second column 35, and socket 24.

An additional link 36 (shown only in figure 1) may be included between first and second vertical members 20 and a 0 25, from the end of rods 22, to provide extra support for the parallelogram.

In use of the device, firstly the relationship Sbetween the major and minor axes of the ellipse must be decided. From this, cosine c can be determined and the anglea set by rotating knob 13.

Next the size of the ellipse must be decided. Coarse adjustment can be effected by varying the length of columns 2 and 35, or lower diagonal member 27 which may be telescopic for this purpose. Fine adjustment is achieved iS.EM 7 r- r i i i r. 1-I- 1 -r i I by rotation of knob 30 to change the shear of the parallelogram. A suitable scale of gradations may be included on knob 30, for instance corresponding to the length of the major axis of the ellipse or any other convenient dimensions. The paralellogram is then locked rigidly by means of the grub screws associated with the joints.

To draw the ellipse column 2 must be held vertically upright and knob 31 turned to cause pen 7 to follow the locus of an ellipse on the horizontal surface intersecting the bottom of column 2. Column 2 can be kept upright during use by the use of a stand and clamp if desired.

While the ellipse is being drawn, rods 21 slide in S sockets 23, rods 22 slide in socket 24, rods 34 slide in pen holder 32, and upper diagonal member 26 telescopes in and out.

00 so Referring now to Figure 3, a mathematical 0 s. interpretation of the device will be given: column 2 is the a 00 vertical axis of rotation of the device. The vertical and diagonal members, the horizontal rods, the radial pin 17, and column 2 all lie in a single plane. The vertical height of the horizontal rods and axis 11 of circular guide means 3 0000 a re fixed. As the device rotates about the column 2, the off* o. following geometry is maintained: horizontal rods 21, 22 and 34 remain perpendicular to column 2; diagonal members 26 and 27 remain parallel, and the parallelogram remains fixed; and describing means 6 follows the locus of an ellipse determined by the angle When the angle a is 0, i [describing means 6 describes a circle, and as the angle a .30 increases, describing means 6 describes an ellipse having a major axis equal to twice the radius of the circle, and the minor axis equal to cosine a multiplied by that value.

In order to draw ellipses where the major axis is less than twice the radial distance between pen 7 and column 2, the apparatus must be reconfigured in one of two ways.

First, as shown in Figure 4, the apparatus may be reconfigured by a telescopic shortening of vertical member 7 4 3EM (after the movement or removal of additional link 36) to form an isoceles trapezium (from vertical members 20 and and diagonal members 26 and 27). Then the diagonal member 27 must be changed to extend towards colum 2.

Alternatively, as shown in Figure 5, the intersection of diagonal member 26 is moved down collar 28, and diagonal member 27 changed as before. Telescopic extension of vertical members 20 and 25 may also be required.

Although the invention has been described with reference to particular examples, it should be appreciated that it may be configured in many other forms. For instance, instead of a single pointed end located at the bottom of column 2, or tripod or flat-based stand may be used. In addition, it should be appreciated that a range of ellipses could be drawn using a simplier apparatus that that described; that is, without the pantograph arrangement 8 and only including rods 21 and 22, and an adjustable distance between block 15 and U-shaped member 16.

Another alternative way of adjusting the size of the ellipse is to make the vertical members 20 and 25 telescopic from below the connection with horizontal rods 22.

It should also be appreciated that the circular guide S means need not comprise two spaced apart rings packed with ball bearings, and a low friction contact arrangement can be

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used instead, such as by using two rings of plastics material sliding directly over one another. Other means may also be provided to fix the angle of inclination of the circular guide means 3 with respect to central column 2, such as the use of a butterfly nut on an end of axis 11.

:30 The device may of course be constructed from any suitable material such as metal or plastics. Some of the components may even be wooden.

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Claims

1. An. ellipsograph, comprising: a support means comprising a vertical column; a circular guide means attached to the support means and rotatable about its origin, the circular guide means also being pivotably adjustable about a horizontal axis colinear with one of its diameters to project an ellipse having the relative lengths of its major and minor axes variable depending on the degree of adjustment, onto a horizontal surface; and a vertical describing means supported by the vertical se*e column such that it is able to remain vertical and move towards, away from and around the vertical column, the vertical describing means also being linked to the circular guide means so that it is constrained to describe a horizontal ellipse having the same relative lengths of major and minor axes as the projected ellipse, as the circular guide means is rotated about its origin. S" 2. An ellipsograph as claimed in claim 1, wherein the circular guide means comprise a pair of coplanar, concentric rings which are rotatable with respect to each other about an axis through their common origin and perpendicular to their plane. An ellipsograph as claimed in claim 2, wherein an annular space separating the two rings is packed with ball bearings.

4. An ellipsograph as claimed in claim 3, wherein the describing means is attached to the outer ring, and the inner ring is pivotally mounted to the support means by means of a pin which passes along a diameter of that ring. r 1Y L -L-iUI l 11 An ellipsograph as claimed in claim 1, wherein a pen holder is attached to the describing means and, in use, a pen is releasably inserted into the holder.

6. An ellipsograph as claimed in claim 1, wherein a pantographic structure is connected between the describing means and a pen holder to enable ellipses of different sizes to be drawn.

7. An ellipsograph as claimed in claim 6, wherein a number of horizontal rods interconnect the vertical column .0 and, the pantographic structure in a slidable fashion to support the pantographic structure, and allow it to slide radially inwards and outwards with respect to the column.

8. An ellipsograph substantially as herein described with reference to the accompanying drawings. DATED this 30th day of August 1991 KHALIL ABDALLAH I :I Lj Ui, By his Patent Attorneys 20 GRIFFITH HACK CO. S:21128B