GB2512297A

GB2512297A - Drawing instrument

Info

Publication number: GB2512297A
Application number: GB201305357A
Authority: GB
Inventors: Nazim Ibne Joomun
Original assignee: JOONA Ltd
Current assignee: JOONA Ltd
Priority date: 2013-03-25
Filing date: 2013-03-25
Publication date: 2014-10-01
Also published as: GB201305357D0

Abstract

A drawing instrument which can be used by children, comprises a ruler arm 6 articulated to a mounting base (Fig.6, 13), and having a locating aperture 7 for a drafting pen or pencil. The mounting base is attached to a transparent head portion 3 to form a vertically slideable assembly which is biased upwardly to a position in which the underside of the mounting base is lifted off the drawing surface. The underside of the mounting base is accommodated within a recess in the underside of the ruler arm 6. This allows the instrument to be laid flat on the drawing surface and used as a ruler. To draw an arc or a circle, the head portion 3 is depressed to push the mounting base onto the drawing surface. The ruler arm can then be rotated about the axis of the mounting base to draw an arc. No sharp point is required and, the mounting base is slideably movable by the disengagement of a click-stop mechanism.

Description

Drawing Instrument The present invention relates to a drawing instrument for drawing ares on a drawing surface.

Conventional compasses have a sharp point (which can be a safety hazard when used by young children) and very often children find them difficult to use. Furthermore, particularly when several arcs or circles are drawn with a common centre, the point can damage the writing surface.

JP 10-193 878 discloses a drawing instrument comprising a circular platform with three feet for supporting it on a sheet of paper or similar writing surface and a conical depression in its centre for locating the point of a pair of compasses. In this manner the paper or other writing surface is protected. However this instrument does not make it significantly easier for a child to use a pair of compasses and does not avoid the requirement for a point on the compasses.

KR 201200029641J discloses a drawing instrument with a large circular mounting base to which an elongate arm is articulated. The arm (which is also hinged at its mid region) has a linear array of apertures for holding a marker, enabling circles of different diameter to be drawn by rotating the arm about the mounting base while the latter is held against a drawing surface. This drawing instrument is also shown in the accompanying Figure 1, which shows the relatively large mounting base 20 carrying a short articulated arm 60a, 60b which is pivotally mounted on its upper surface. An aperture 70 (shown somewhat enlarged for the sake of clarity) in arm section 60a locates a marker which can be used to draw a circle or are, centred on pivot axis x of the mounting base, on a drawing surface on which the mounting base rests.

Because the arm 60a pivots on top of the mounting base its underside is higher than the underside of the mounting base (and the drawing surface) except at its outer end.

Accordingly the arm portion 60a cannot be laid flat on the drawing surface and is not suitable for use as a ruler.

Furthermore the mounting base is relatively large in plan view (the area of the base is greater than the area of the arm 60a, 60b), tending to interfere with any straight line drawn along the edge of the arm, and making the instrument somewhat cumbersome when moved about the drawing surface.

The present invention provides a drawing instrument comprising an elongate ruler arm articulated to a mounting base, the ruler arm carrying a locating means for a marking instrument, the locating means being longitudinally spaced apart from the axis of articulation of the mounting base and ruler arm whereby in use with a marking instrument, the ruler arm can be rotated about the axis to draw an arc on a drawing surface, the mounting base having an underside which in use is substantially flush with or higher than the underside of the adjacent ruler edge region of the ruler arm whereby the ruler arm can be laid flat on the drawing surface.

Because the arm can rest on the drawing surface, the instrument can be used as a ruler as well as a pair of compasses.

Preferably said mounting base is axially movable relative to said ruler arm to a raised position in which the underside of the mounting base is supported by the ruler arm above said drawing surface.

In this configuration, the mounting base does not impede sliding of eg one end of the ruler arm over the drawing surface, so the instrument can be moved easily between eg two parallel positions on the drawing surface, much like a conventional ruler.

Preferably said mounting base is resiliently biased towards said raised position.

This leaves the user's hands free to manipulate the instrument when it is being used as a ruler.

Preferably said mounting base is provided with an upper head portion which is arranged to be held down by a user when drawing an arc.

Preferably said underside of said mounting base has a gripping surface portion which is engageable with said drawing surface when drawing an arc.

These last two features enable thc mounting base to be held securely against the drawing surface so that the centre of the arc is not inadvertently nudged into a different position.

In one embodiment said mounting base is generally cylindrical and locates a compression spring which biases it upwardly relative to said ruler arm. I0

Advantageously, said axis is indicated on said mounting base and is viewable from above by a user.

In a preferred embodiment said mounting base does not preject beyond any edge of said lower surface of said ruler arm.

Preferably the area of said drawing surface covered by said mounting base is less than (more preferably less than 25% of most preferably less than 10% of) the area bounded by the outer periphery of said ruler arm.

These last two features enhance the balance of the drawing instrument, making it easier to re-position on the drawing surfhce, and enable the entire periphery of the ruler arm to be used for drawing eg straight lines, without interruption by any pmjecting portion of the mounting base.

Preferably the spacing between the axis and the locating means (which is eg a small aperture for receiving the tip of a marker pen or a pencil) is adjustable to adjust the radius of the arc.

In a preferred embodiment the mounting base is slidable along the ruler ant to adjust the spacing.

Other preferred features are defined in the dependent claims.

A preferred embodiment is described below by way of example only below with reference to Figures 2 to 6 of the accompanying drawings. In the drawings: Figure I (which has been referred to above) shows a drawing instrument as disclosed in KR 20120002964U in plan view; Figure 2 is a sketch perspective view from above right of a drawing instrument in accordance with the present invention; Figure 3 is a partial sketch perspective view from above left of the drawing instrument of Figure 2; Figure 4 is a plan view of the drawing instrument of Figures 2 and 3, being used with 1 5 a marking instrument to draw an arc; FigureS is a partial exploded sketch perspective view from one end of the instrument of Figures 2 to 4, partially cut away to show the resilient mounting of mounting base 13, and Figure 6 is a partial sketch perspective view from below of the instrument of Figures 2 to 5, showing the base surface of mounting base 13.

It should be noted that the parts of the drawing instrument of Figures 2 to 6 which broadly correspond to the parts of the Korean drawing instrument of Figure 1 have reference numerals in which the zeros of Figure 1 are omitted. Thus mounting base of Figure 1 is to be contrasted with mounting base 13 of Figures 5 and 6, for

example.

Referring to Figures 2 and 3, the drawing instrument I comprises a ruler arm 6 carrying a slider assembly 2 which includes a mounting base (not shown in these Figures) about which thc drawing instrument can be pivoted. The slider assembly 2 comprises a transverse arm 4 which locates the assembly on the upper surface of ruler arm 6, and an upper head portion 3 which is connected to the mounting base and is shaped and dimensioned to be held down by the fingers or palm of a user's hand. The head portion 3 and mounting base are biased upwardly within a tubular barrel portion 9 of the slider assembly. Head portion 3 as well as ruler arm 6 arc formed of transparent plastics material such as polystyrene.

Tubular barrel portion 9 slides longitudinally within a longitudinal channel or slot e formed in the ruler arm 6. The lower end of barrel portion 9 protrudes below the lower edge of channel e but lies above the common plane of the two long edges of the ruler arm 6, since the underside of the ruler arm is recessed along the length of channel e.

A locating aperture 7 is formed at each end of the ruler arm 6 and has a diameter matched to that of a marking pen or a pencil.

One longitudinal edge region of the ruler arm 6 is turned upwardly as shown best in Figure 2, and, as is shown in Figure 3, the inwardly-facing surface of this upturned edge has a click stop surface s comprising a linear array of alternate recesses and projections which engage complementary recesses and/or projections (not shown) in an outwardly-facing surface of an upturned end of transverse arm 4. This click stop mechanism enables the slider assembly 2 to be retained in a desired position along the ruler arm 6. Tt can be moved rapidly along the ruler arm by bending the upturned portion of arm 4 inwardly towards barrel portion 9 to release its engagement with click stop surface s. In this manner the instrument can be set to draw an are or circle of a desired radius.

As shown in Figure 4 a central cross hair marking 8, indicating the axis of rotation of the assembly about the mounting base, is formed on the base of the mounting base and is visible through transparent head portion 3. In use, the tip of a drafting pen or pencil m is inserted in locating aperture 7 50 it rests on the drawing surface, with the cross hair marking 8 on the desired centre, the mounting base is held against the drawing surface by pressing with the fingers or palm of one hand on head portion 3, and then the ruler arm 6 is rotated with the other hand to draw eg an are a. A scale (not shown) may be provided adjacent channel e to enable the arc radius to be read off on sliderarm4.

Since there is a minimum distance between the axis of rotation defined by cross hair marking 8 and the centre of locating aperture 7, there is a lower limit on the radius of any arc or circle that can be drawn in the manner described above. In order to enable ares and circles with radii below this lower limit to be drawn, a series of circular template apertures h of successively increasing radii (all at or below this lower limit) are formed in the ruler arm 6, as shown in Figures 2, 3 and 4.

The mounting base 13 and its mounting on slider assembly 2 will now be described with reference to Figures 5 and 6.

Figure 5 shows mounting base 13 disengaged from transparent head portion 3. The mounting base 13 comprises an expanded cylindrical base portion and an upper tubular portion which is fitted (eg by a snap fit connection or adhesive) to a complementary central cylindrical projection on the underside of head portion 3. The resulting assembly can slide vertically within barrel portion 9.

Barrel portion 9 includes an internal annular ledge which supports a compression spring 10, the upper end of spring 10 bearing against the underside of head portion 3 around its cylindrical projection. Accordingly the assembly of mounting base 13 and head portion 3 is resiliently biased upwardly by spring 10 to a position in which the underside of mounting base 13 is raised above the common plane of the edges of ruler arm 6, ie out of contact with a drawing surface (not shown) on which the ruler arm lies flat. In this configuration the instrument can be used as a conventional ruler and is provided on one of its ruler edges with eg a millimetre scale sd for this purpose.

Irrespective of the position of slider assembly 2 on the ruler arm 6, the underside of mounting base 13 is higher than the adjacent portion of this ruler edge, being accommodated in the recess formed in the underside of the ruler arm 6 on each side of channel c. In a variant, the ruler arm 6 could be formed from a flat strip which is dished in the transverse direction to accommodate the underside of the mounting base.

S It will be noted that, unlike the drawing instrument shown in Figure 1, the area of the drawing surface covered by mounting base 13 is much less than the area bounded by the outer periphery of ruler arm 6. Accordingly, the instrument of Figures 2 to 6 is much less cumbersome.

As shown in Figure 6, the barrel portion 9 includes two tangs t which extend beneath and engage the edges of channel c. These tangs are inserted from above into channel c (as shown in Figure 5) before the mounting base 13 is inserted from below into the barrel portion and fitted to the head portion. The barrel portion 9 is connected to slider arm 4 eg by a snap fit connection or adhesive.

Figure 6 also shows cross hair marking 8 formed on the underside of a transparent base wall of mounting base 13. In order to ensure a good grip on the drawing surface, a ring 13r of high friction material such as rubber is mounted on the lower surface of the base wall of the mounting base and surrounds cross hair marking 8.

The vertical travel of the assembly of mounting base 13 and head portion 3 is sufficient for the ring I 3r to be pressed firmly against the drawing surface. A radially-extending indicator 9A projects from barrel portion 9 and indicates the angular position of the ruler arm 6 on an angular scale sc2.

Because the instrument can be used with two hands, it is easier to use than a conventional pair of compasses, and because no sharp point is required, it is also safer. It is therefore particularly suitable for young children.

Claims

Claims 1. A drawing instrument comprising an elongate ruler arm articulated to a mounting base, thc ruler arm carrying a locating means for a marking instrument, thc locating means being longitudinally spaced apart from the axis of articulation of the mounting base and ruler arm whereby in use with a marking instrument, the ruler arm can be rotated about the axis to draw an arc on a drawing surface, the mounting base having an underside which in use is substantially flush with or higher than the underside of the adjacent ruler edge region of the ruler arm whereby the ruler arm can be laid flat on the drawing surface.
2. A drawing instrument according to claim 1 wherein said mounting base is axially movable relative to said ruler arm to a raised position in which the underside of the mounting base is supported by the ruler arm above said drawing surface.
3. A drawing instrument according to claim 2 wherein said mounting base is resiliently biased towards said raised position.
4. A drawing instrument according to any preceding claim wherein the area of said drawing surface covered by said mounting base is less than the area bounded by the outer periphery of said ruler arm.
5. A drawing instrument according to any preceding claim wherein said mounting base is provided with an upper head portion which is sarranged to be to be held down by a user when drawing an arc.
6. A drawing instrument according to claim 5 as dependent on claim 3, wherein said mounting base is generally cylindrical and locates a compression spring which biases it upwardly relative to said ruler arm.
7. A drawing instrument according to any preceding claim, wherein said axis is indicated on said mounting base and is viewable from above by a user.
8. A drawing instrument according to any preceding claim, wherein said underside of said mounting base has a gripping surface portion which is engageable with said drawing surface when drawing an arc.
9. A drawing instrument according to claim 8 as dependent on claim 7, wherein said gripping surface portion extends around said indicated axis.
10. A drawing instrument according to any preceding claim wherein said mounting base does not project beyond any edge of said lower surface of said ruler arm.
11. A drawing instrument according to any preceding claim wherein the spacing between said axis and said locating means is adjustable to adjust the radius of said arc.
12. A drawing instrument according to claim 11 wherein said mounting base is slidable along said ruler arm to adjust said spacing.
13. A drawing instrument according to claim 12, wherein a longitudinal slot is formed in said ruler arm and said rotary bearing is slidable along said longitudinal slot.
14. A drawing instrument according to claim 13 wherein said mounting base is provided with a generally tubular enclosure which has lower tang portions which engage the underside of said ruler arm at the edges of said longitudinal slot.
15. A drawing instrument according to any of claims 11 to 14 wherein the longitudinal movement of said mounting base on said ruler arm is constrained by a click stop mechanism.
16. A drawing instrument according to any of claims 11 to 15, further comprising a scale which indicates the radius of said are.
17. A drawing instrument according to any preceding claim wherein a lower surfacc of said ruler arm has a longitudinal recess into which said mounting base extends.
18. A drawing instrument according to any preceding claim wherein said locating means is an aperture shaped and dimensioned to receive the tip of a marker pen or pencil.
19. A drawing instrument according to any prcccding claim wherein said mounting base is provided with an angular scale.
20. A drawing instrument according to any preceding claim wherein said ruler arm has a linear scale adjacent a ruler edge thereof
21. A drawing instrument according to any preceding claim, further comprising one or more circular or arcuate templates having an indicated size which is smaller than the smallest circle or arc which can be drawn by rotation of said ruler arm on said mounting base.
22. A drawing instrument according to any prcccding claim wherein said ruler arm is made of transparent plastics material.
23. A drawing instrument substantially as described hercinabovc with reference to Figures 1 to 5 of the accompanying drawings.