Rolling ruler

The present rolling ruler includes a ruler body having a through hole, a shall having two ends and sleeving thereon the ruler body, and two rollers respectively mounted on the two ends for translating the ruler body. One characteristic of present invention is that different scales are provided on edges of a ruler body.

FIELD OF INVENTION 
The present invention relates to a ruler, and more particularly to a 
rolling ruler. 
BACKGROUND OF THE INVENTION 
Among defects of conventional rulers, a user often encounters difficulties 
in drawing parallel lines of different scales due to insufficient scales 
provided and in preventing the ink from contaminating the working sheet. 
Accordingly, this invention presents a rolling ruler to solve previous 
time- and labor-consuming problems. The present invention is based on the 
recognition that if the active edge of the ruler body can be slightly 
risen, the ink will no more contaminate the working sheet. Further, it 
would be extremely convenient if different scales may be selectively used 
without the necessity of changing the ruler body provided with the 
different scales. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide a rolling ruler with 
multiple scales and/or a secondary ruler for drawing sets of horizontal 
and vertical parallel lines. 
In accordance with the present invention, a rolling ruler comprises a ruler 
body having a through hole, a shaft having two ends and sleeving thereon 
the ruler body, and two rollers respectively mounted on the two ends for 
translating the ruler body. 
In accordance with another aspect of the present invention, the ruler body 
may be generally of a triangular cross-section provided with six different 
scale edges. Alternatively, the cross-section of the ruler body may also 
be quadrangular or a cross having four pointed ends and provided with 
eight different scales. 
In accordance with another aspect of the present invention, the surfaces of 
the two rollers may include an outer layer having a relatively high 
frictional coefficient or being roughened to be frictional for enabling 
the rollers to be positively controlled in motion or at a stop. 
In accordance with another aspect of the present invention, the rolling 
ruler further comprises two shaft mountings inserted into two ends of the 
ruler body for respectively mounting the two shaft ends. 
In accordance with another aspect of the present invention, the rolling 
ruler further comprises a secondary ruler movably ! held perpendicular to 
the rolling ruler and preferably having a triangular cross-section 
provided with six different scales. 
In accordance with another aspect of the present invention, the rolling 
ruler further includes an extension device which comprises a first groove 
sliding therein the rolling ruler and a second groove perpendicular to the 
first groove and detachably attaching the to the secondary ruler. Either 
one of the first and the second grooves generally presents a V-shaped 
cross-section. 
In accordance with another aspect of the present invention, the shaft of 
the rolling rider is rotatably mounted in the through hole or the rollers 
are rotatably mounted on the two shaft ends respectively. 
The present invention may best be understood through the following 
description with reference to the accompanying drawings, in which:

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIGS. 1 and 2, a rolling ruler according to the present 
invention includes a ruler body A having a through hole A1, a shaft B 
having two ends B1 and sleeving thereon the ruler body A, and two rollers 
C respectively mounted on the two ends B 1 for translating ruler body A. 
Referring to FIGS. 2 and 3, the ruler body A presents a triangular 
cross-section and three scale surfaces A2, A3 and A4. On the two edges A5 
of each of the surfaces A2, A3 and A4 are provided with two different 
scales A21, A31 or A41. So, a user can choose one of the scales and draw 
parallel lines L by moving the rightly turned ruler body A backwards or 
forwards. 
Referring to FIG. 4, since a gap appears if a scaled edge A5 of the ruler 
body A is raised slightly above the working plane P upon drawing, the ink 
will not flow through the edge A5 to moisten or spread over the working 
sheet. While applying a drawing tool without ink, such as a pencil M, one 
can let the edge A5 of the ruler body A touch the working plane P. 
Referring to FIG. 5, to decrease the friction of the shaft B mounted in the 
through hole A1 of the ruler body A, shaft mountings S are respectively 
inserted in both ends of the ruler body A in order that the shaft B is 
supported evenly and axially and can roll more smoothly. Referring to FIG. 
6, the hollow central part A11 of the ruler body A has two shaft mountings 
T respectively mounted on its both ends and having two coaxial shaft holes 
T1 through which the shaft B can pass. Also, each of the two rollers C has 
a concentric hole C2 for mounting therein one of the two ends of the shaft 
B to decrease a rolling friction between the shaft body B and the inner 
surface of the ruler body A. Further, the cross-section of the shaft 
mountings T may be shaped corresponding to that of the hollow central part 
A11 of the ruler body A. 
Referring to FIGS. 7 and 7A, according to the present invention, the 
cross-section of the ruler body A may be quadrangular AT to increase 
different scales on its surfaces. Also, referring to FIGS. 8 and 8A, 
according to the present invention, the cross-section of the ruler body 
may be a cross AS with four points. These two embodiments are not only for 
preferably increasing different scales, but also for easily reading the 
scale and drawing lines. 
Referring to FIG. 9, to increase the friction of the roller C surface, it 
is favorable to have a roughened roller surface C1. Further, to roll over 
a smooth glass-plate, it is also desirable to apply a relatively high 
frictional coefficient outer layer CR over the roller surface C1 for 
enabling the rollers to be positively controlled in motion or at a stop. 
Referring to FIG. 10, the rolling ruler A can further include a secondary 
ruler D movably held perpendicular to the rolling ruler body A and 
preferably having a triangular cross-section to be provided with six 
different scales. And either one of the first and the second grooves 
generally presents a V-shaped cross-section. 
Referring to FIG. 10A, the ruler body A and the secondary ruler D are 
brought together by an extension device E which comprises a first groove 
E1 sliding therein the rolling ruler A, so that a horizontal displacement 
M can be exercised. Referring to FIG. 10B, a second groove E2 of the 
extension device E is perpendicular to the first groove E1 and the second 
ruler D can be detachably attached thereto, so that parallel lines N 
perpendicular to the ruler body A may be drawn. Accordingly, a horizontal 
displacement between the parallel lines N can be read by sliding one edge 
D 1 of the secondary ruler D along one relevant edge A5 of the ruler body 
A. 
To sum up, with the ruler body A, the problem of the ink being spread over 
the working sheet through the ruler edge can be overcome. Further, with 
the rolling function of the rollers C, the secondary detachable ruler D 
perpendicularly attached to an extension device E and different scales 
provided on the ruler body A, a user can accurately and effectively draw 
parallel lines with distances calculated in a desired one of different 
scales. 
While the invention has been described in terms of what are presently 
considered to be the most practical and preferred embodiments, it is to be 
understood that the invention need not be limited to the disclosed 
embodiment. On the contrary, it is intended to cover various modifications 
and similar arrangements included within the spirit and scope of the 
appended claims which are to be accorded with the broadest interpretation 
so as to encompass all such modifications and similar structures.