WO1989004770A1

WO1989004770A1 - Drawing instrument

Info

Publication number: WO1989004770A1
Application number: PCT/AU1988/000460
Authority: WO
Inventors: Helen Chui Lan Chai
Original assignee: Helen Chui Lan Chai
Priority date: 1987-11-26
Filing date: 1988-11-25
Publication date: 1989-06-01
Also published as: AU2805489A

Abstract

A multi-purpose drawing instrument comprising a set square (1) with a measured graduations on its sides, an aperture (13) formed in said set square (1), a flat disc (5) supported for rotation within said aperture, said disc (5) being formed with a multiplicity of openings (7) for receiving a marking instrument, the openings (7) being spaced at predetermined radii from the centre of the disc to enable circles of radii corresponding to said openings to be drawn by rotating the disc by means of the marking instrument engaging one of said openings (7), a retaining ring (9) overlying the edge of said disc to retain said disc in said aperture (13), said retaining ring having gradations (10) divided into 360° to enable a desired angle to be drawn by rotating the disc (5) through a predetermined arc from any set point, additionally the set square (1) has template type openings (11) for drawing smaller diameter circles and other shapes such as benzene rings (12).

Description

1 TITLE : DRAWING INSTRUMENT

2 Fi eld of the Invention :

3 T h i s i n v e n t i o n r e l a t e s t o a n i m p r o v e d d r a w i n g

4 instrument .

• 5 Background of the Invention:

6 At present students engaged in the study of geometrical

7 functions are required to carry a number of separate 8. instruments in order to draw circles, measure angles and 9 perform other drawing functions. These instruments include

10 a compass, dividers, a ruler and a protractor. Such

11 instruments take time to set up and use and must be carried

12 from one place to another, and this is generally

13 inco venient. Similar problems are encountered by

14 professionals engaged in engineering, architectural and

15 similar activities.

16 Summary of the Invention and Objects:

17 It is an object of the present invention to provide a

18 multi-purpose drawing instrument in which the functions

19 performed by a number of different instruments may be

20 performed more conveniently.

21 The present invention therefore provides a drawing

22 instrument comprising a shaped supporting member, a flat

23 disc supported for rotation within an aperture formed in

24 said member, said disc being formed with a multiplicity of

25 openings for receiving a marking instrument, said openings

26 being spaced at predetermined radii from the centre of said

27 disc to enable circles of radii corresponding to said

28 openings to be drawn by rotating said disc by means of a

29 marking instrument engaging in one of said openings.

30 In one form of the invention, the shaped supporting

31 member is in the form of a set square so that both straight

32 lines and circles may be drawn using the instrument.

33 In a presently preferred form of the invention, the

34 disc is associated with a scale surrounding its perimeter by

35 means of which the disc may be accurately rotated through a

36 predetermined angle. In this way, the instrument is able to

37 perform the function of a protractor as well.

38 The straight edges of the set square are preferably marked with measured gradations so that desired lengths may be accurately drawn. In addition, the supporting member may be performed with a number of template plate-type openings to enable circles of smaller diameters to be drawn and to enable other shapes, such as benzene rings, to also be drawn. In the presently preferred form of the invention, a second smaller rotatable disc is also supported by the supporting member to enable circles of smaller diameters to be drawn. The shaped supporting member is preferably moulded from clear plastics material in a manner similar to known drawing instruments such as set squares, protractors and the like. The supporting member is formed with at least one circular opening surrounded by a recessed portion adapted to receive the edge of a circular disc for rotation within said recessed portion. A retaining ring overlies said disc to hold it in its recessed portion, said ring being removably attached to said supporting member, such as by a bayonet- type locking mechanism formed on the edge of the ring and in the supporting member. The retaining ring operates to retain the disc within its recessed portion whilst allowing free rotation of the disc with respect to the supporting member. The retaining ring is preferably marked with angular gradations to enable the disc to be accurately rotated through any selected angle. - Brief Description of the Drawings: A presently preferred form of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a plan view of the improved drawing instrument in assembled condition; Figure 2 is a plan view showing the drawing instrument with the various parts removed; Figure 3 is a plan view of the large rotatable disc; Figure 4 is a plan view of the retaining ring for use with the rotatable disc; Figures 5 and 6 are equivalent views of the smaller rotatable disc and associated retaining ring, and Figure 7 is a plan view of a template formed with a series of holes of increasing diameter. Description of Preferred Embodiment: Referring firstly to Figure 1 of the drawings, the drawing instrument will be seen to comprise a set square shaped body 1 of clear plastics material having marked gradations 2, 3 and 4 along its respective straight edges and supporting a centrally located large rotatable disc 5 and a smaller rotatable disc 6, each of which is formed with a series of openings 7, 8 through which a marking instrument may project to enable circles of various diameters to be drawn. The openings 7,8 are labelled as shown to indicate the radius, in centimetres, of the circles which will be drawn by a writing instrument engaging the respective openings 7,8. The larger disc is surrounded by a retaining ring 9 having gradations 10 divided into 360° to enable any desired angle to be drawn by rotating the disc 5 through a predetermined arc from any set point. Templates 11 and 12 are also formed in the set square body 1 to enable the drawing of smaller circles and benzene rings to be drawn. Referring now to Figure 2 of the drawings, it will be noted that the set square shape support 1 is formed with a central circular opening 13 which is surrounded by a recessed portion 14 which is moulded into the support 1 and is adapted to receive the peripheral edge of the disc 5 to enable the disc 5 to be rotated with respect to the support 1. The support is also moulded with retaining recesses 15 spaced around the periphery of the recessed portion 14, and adapted to lockably receive bayonet lugs 16 formed on the periphery of the retaining ring 9 by insertion of the lugs 16 into the locking recesses 15 whereupon the ring 9 is rotated to locate the lugs under the retaining portions formed in the locking recesses 15. It will be noted that the inner periphery of the locking ring 9 overlies the outer periphery of the disc 5 so that the disc is positively located in its recess 14 whilst still allowing for rotation of the disc with respect to the support 1. A smaller diameter opening 17 surrounded by a similar recess 18 is formed in the support 1 as shown and receives the smaller rotatable disc 6 which is kept in position by means of a locking ring 19 attached to the support 1 in a manner similar to the locking ring 9 described above. ^" The support 1 is also formed with a generally rectangular recess 20 which receives the template 21 (Figure 8) which has a series of apertures of increasing diameter formed therein. The location of the template 21 in the recess 20 has the advantage of containing any ink which might leak from the marking device during the drawing of circles using the template 21. While the presently preferred embodiment has been described as applied to a set-square shape support, it will be appreciated that the support may be made in any desired shape although a set-square-shaped is clearly convenient. It will also be appreciated that the method of attaching the rings 9 and 19 to the support 1 may be modified to suit desired manufacturing techniques. For example, the rings 9 and 19 may be adhesively secured or heat welded to the support 1 since once the discs 5 and 6 are located in their recesses 14 and 18, there would be little need for the subsequent disassembly.

Claims

CLAIMS: 1. A drawing instrument comprising a shaped supporting member (1), a flat disc (5) supported for rotation within an aperture (13) formed in said member (1), said disc (5) being formed with a multiplicity of openings (7) for receiving a marking instrument, said openings (7) being spaced at predetermined radii from the centre of said disc to enable circles of radii corresponding to said openings to be drawn by rotating said disc by means of a marking instrument engaging in one of said openings. 2. The instrument of claim 1, wherein said shaped supporting member (1) is in the form of a set square. 3. The instrument of claim 2, wherein the straight edges of said set square are marked with measured gradations (2,3,4). 4. The instrument of claim 1, 2 or 3, further comprising a scale means (10) surrounding said aperture (13) whereby the disk (5) may be rotated through any desired angle to perform the function of a protractor. 5. The instrument of any preceding claim, further comprising a second smaller rotatable disc (6) supported in an opening (17) in said shaped supporting member (1) and formed with a multiplicity of openings (8) for receiving a writing instrument whereby smaller circles may be drawn. 6. The instrument of any preceding claim, further comprising a template having small circular openings (11) formed therein to enable small circles to be drawn, and/or other shaped openings (12) to enable other shaped small or benezene rings to be drawn. 7. The instrument of any preceding claim f-urther compr-l.sing a retaining ring (9) overlying said edge of said disc (5) and being attached to said member (1) to retain said disc (5) in said opening (13) while permitting rotation of said disc (5) within said opening (13). 8. A drawing instrument comprising a shaped supporting member (1), a circular opening (13) in said member (1) and surrounded by a recessed portion (14), a circular disc (5) shaped to be received in said opening (13) with its edge 1 received in said recessed portion (14), a retaining ring (9)

2 overlying said edge of said disc (5) and being attached to

3 said member (1) to retain said disc (5) in said opening (13)

4 while permitting rotation of said disc (5) within said

5. opening (13), said disc (5) being formed with a multiplicity

6 of openings (7) for receiving a marking instrument, said

7 openings (7) being spaced at predetermined radii from the

8 centre of said disc to enable circles of radii corresponding

9 to said openings to be drawn by rotating said disc by means 0 of a marking instrument engaging in one of said openings. 1 9. The instrument of claim 7 or 8, wherein said retaining 2 ring (9) is removably attached to said supporting member 3 (1). 4 10. The instrument of claim 8 or 9, further comprising the 5 features of any one of claims 2 to 6.