US2563191A - Illuminated draftsman's guide - Google Patents

Description

Aug. 7, 1951 R. w. RUSS ILLUMINATED DRAFTSMANS GUIDE Filed July 31, 1950 RAYMOND W. RUSS Snventor Patented Aug. 7, 1951 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to drafting instruments and has reference to straight and curved edges for guiding pencil points and the like when making drawings.

Although most guides referred to, such as T squares, triangles, draftsmans curves and the like, either have transparent edges or are made entirely of transparent material, they cast very pronounced shadows along the side of the guide remote from the source of light. Such shadows are the cause of eye strain when the draftsman has to locate points falling within the shadow. It is also difficult for the draftsman to locate such points, with the result that scale drawings are not always as accurate as desired.

The purpose of the invention is to provide an edge for a pencil guide or the like which will at least partially illuminate the drawing adjacent the guide.

The invention will be more readily understood by reference to the accompanying drawings and the following description.

Figure 1 is a perspective view of a portion of a drafting room, and showing several guides embodying the present invention placed on a drafting board.

Figure 2 is an enlarged broken perspective of a drawing and showing a triangle embodying the invention placed thereon.

Figure 3 is a vertical sectional view of a guide made in accordance with the invention and showing the manner in which light is transmitted through the guide by means of arrows.

In Figure 1, a drafting board I is positioned near a window II allowing light passing therethrough to fall on the surface of a drawing l2. A shadow II normally falls on the drawing I! on the side of the pencil guide, such as the triangle l4, away from the window II. A pencil guide, as herein referred to. may be any flat instrument used for guiding a pencil I! along its edge when drawing lines, such as l6, H or II, and which guide may be in the form of the referred to triangle H, a draftsmans curve II. or a T square 2| having transparent edges 2|. The material used, in accordance with the invention, is transparent fluorescent plastic of the type which absorbs light through its broad surfaces 22 and emits light along its edges 23. The transmission of light is best carried out when the flat surface is so smooth that it appears to be slick, and when the edges are at least slightly rough, at least to that degree where they may be referred to as being frosted. The guides l4 and 20 may be entirely made of the described material, or the material may be employed only along their edges, as shown in connection with the T square Hi.

The operation of the invention is best illustrated in Figure 2 where the intensity of the shadow i3 is decreased by reason of the light emitting from the edge 23 of the triangle H. The line is parallel with and near the edge 23 is sufficiently illuminated for drafting purposes. Since the edge 23 glows, there is a very marked contrast between said edge and the line l6 whereby the two may be readily distinguished for plotting points and the like along the line.

The present invention is not limited to the construction herein shown and described, but may be made in many ways within the scope of the appended claim.

What is claimed is:

A pencil guide for use in making drawings comprising a transparent flat body of fluorescent plastic material having the outline of a conventional draftsmans guide, and the pencil guides edges of which are at least slightly rough.

RAYMOND W. RUSS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Hayward Aug. 18, 1942 OTHER REFERENCES Number

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