GB2193929A - Ruler - Google Patents

Abstract

A ruler comprises an elongated sheet body 10 having indicia marked thereon and a protractor 13 formed at one end thereof. The indicia comprise length scales at both ruler edges 11 and 12, uniformly spaced longitudinal lines 16 and dot pairs 17 used for drawing parallel lines. A transverse line 18 is used for drawing perpendicular lines, and inclined lines 19 are used for drawing inclined lines. The straight edge 14 of the protractor 13 passes through the protractor centre 15 and extends to join and cooperate with the ruler edge 12 to be used for drawing lines inclined at any angle to a given datum line. The scale on edge 12 may be zeroed, as shown, at the end of the ruler remote from the protractor 13, or, alternatively, may be zeroed at protractor centre 15. <IMAGE>

Description

SPECIFICATION Ruler The present invention relates to a ruler, and in particular to a combined ruler and protractor.

Rulers are common drawing instruments. To draw parallel lines, an additional ruler or set square is required. Furthermore, to draw parallel lines inclined at an angle to a datum line, a protractor is also required.

The present invention aims to simplify this drawing procedure. Accordingly, the present invention provides a ruler comprising an elongate body having indicia marked thereon, wherein a protractor is provided at an end of the body.

Preferred features of the invention will be apparent from the following detailed description of the invention and the accompanying claims.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of a ruler according to the invention; Figure 2 to 5 are plan views of the ruler of Figure showing different applications of the ruler.

Referring to the drawings, Figure 1 shows a ruler comprising an elongated sheet body 10 formed of transparent plastics material. The ruler is thin either can be placed face down without causing difficulties of parallax.

The body 10 comprises two longitudinal edges 11 and 12 at which different length scales are marked, and a protractor 13 at one end thereof. The protractor 13 has a straight edge 14 which passes through a protractor centre 15 and extends to join the edge 12 of the elongated sheet body 10. The length scale at the edge 12 extends to and ends at the protractor centre 15.

Uniformly spaced parallel lines 16 are provided on the elongated sheet body 10 in a longitudinal direction. Two or more rows of uniformly spaced dots 17 are provided on the elongated sheet body 10 in between the lines 16 in a transverse direction.

At the other end of the elongated sheet body 10 remote from the protractor 13, the length scales at the edges 11 and 12 start at a transverse line 18. Two lines 19 extend from the point of intersection 20 of the sheet body edge 11 and the transverse line 18, at angles of 30 and 45" with the edge 11 re spectively.

Figure 2 shows how the ruler is used to draw perpendicular lines and parallel lines. To draw a line perpendicular to a given datum line, the transverse line 18 or the 90 line of the protractor 13 is placed along the datum line. Then lines perpendicular to the datum line can be drawn by using the ruler edges 11 and 12.

To draw lines parallel to a given datum line, the longitudinal lines 16 or the longitudinally corresponding pairs of dots 17 on the ruler elongated sheet body 10 are placed along the datum line, as shown in Figure 2. Lines parallel to the datum line can then be drawn by using the ruler edges 11 and 12.

Preferably, the longitudinal lines 16 and the longitudinally corresponding pairs of dots 17 are provided on the body 10 at some selected displacement from both edges 11 and 12, for example at integral multiples af millimeters or fractions of an inch. With this design the separation between parallel lines can be conveniently selected, for example, when drawing a musical stave.

Alternatively, parallel lines can be drawn by sliding the ruler with one of straight line marked on the ruler tracing along a given straight datum line on the paper, the parallel lines being drawn by using a straight edge of the ruler.

Figure 4 shows how the ruler can be used to draw inclined lines. To draw a line inclined at an angle to a given datum line, the ruler is placed over the datum line with the protractor centre 15 lying thereon. The ruler is then rotated about the protractor centre 15 until the desired angle is read by the protractor 13 against the datum line. Hence a line inclined at a particular angle to the datum line can be drawn by using the ruler edge 11 or 12. The length of the line drawn or measured from the protractor centre 1 5 can be read from the length scale at the edge 12.

Particularly if the centre is at an integral number of units on the scale 12.

In another embodiment, the scale may be zeroed at the centre of the protractor to facilitate measurement therefrom.

Figure 5 shows how the ruler can be used to draw a line inclined at a special angle, such as 30 , 45" or 60 , to a given datum line.

This is achieved by placing the ruler over the datum line with either one of its lines 19 lying there along inclined line can then be drawn using the ruler edge 11 or 12.

To draw addtional parallel lines inclined at the same angle to the datum line, one aligns the longitudinal lines 16 and dot pairs 17 with the inclined line, (or use the method of sliding the ruler along the datum line).

Advantageously, if a line is drawn using the ruler edge 11 and starting from the point 20, its length can directly be read from the length scale at the edge 11.

Advantageously, if a line is drawn using the ruler edge 12 and starting from the protractor centre 15, its length can be read directly from the length scale at the edge 12.

By providing the protractor 13 at one end of the elongated sheet body 10, a curved edge of protractor is exposed and can be readily used for marking and measuring angles.

Advantageously, the ruler is thin and transparent so that it can be used on both sides for convenience without introducing errors from parallax.

Various modifications will be apparent to those in the art. For example, the protractor 13 may be of elliptical or even rectangular shape. It is desired to include all such modifications as fall within the scope of the invention.

Claims (12)

1. A ruler comprising an elongate body having indicia marked thereon, wherein a protractor is provided at an end of the body.

2. A ruler as claimed in claim 1, wherein the protractor has a straight edge passing through its centre and a curved edge.

3. A ruler as claimed in claim 2, wherein the straight edge of the protractor forms part of or is an extension of a longitudinal edge of the ruler.

4. A ruler as claimed in claim 1, 2 or 3, wherein the elongate body is transparent.

5. A ruler as claimed in claim 4, wherein uniformly spaced parallel lines are provided on the elongate body in the longitudinal direction.

6. A ruler as claimed in claim 4 or 5, wherein at least two rows of uniformly spaced dots are provided on the elongate body.

7. A ruler as claimed in claim 6 when dependent upon-claim 5, wherein the dots are positioned between the uniformly spaced parallel lines, the rows extending transversely of the body.

8. A ruler as claimed in any preceding claim, wherein a length scale provided at a longitudinal edge of the body starts at an end of the body distal from the protractor.

9. A ruler as claimed in anyone of claim 1 to 8, wherein a length scale provided at the longitudinal edge of the body joining the straight edge of the protractor starts at the centre of the protractor.

10. A ruler as claimed in claim 7, wherein a length scale is provided on each longitudinal edge of the ruler, the length scales starting from a common position in the longitudinal direction of the ruler.

11. A ruler as claimed in anyone of claims 4 to 6, wherein at least one line is provided, starting at the intersection of a line transverse of the ruler body and a longitudinal edge, the line subtending an angle said ruler edge.

12. A ruler substantially as hereinbefore described with reference to the accompanying drawings.