Geometrical instruments – Straightedge type – Plural straightedges – relatively moveable
Patent
1985-06-11
1986-04-29
Little, Willis
Geometrical instruments
Straightedge type
Plural straightedges, relatively moveable
33DIG9, B43L 706
Patent
active
045847797
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a square set particularly suitable for trimming photographic films, drawing sheets or the like into a rectangular shape.
BACKGROUND OF THE INVENTION
Compilation of materials for catalogues, books, newspapers or the like invariably involves trimming jobs, for example, trimming of an image on a photographic film or drawing to be fitted in a specified space or frame on a catalogue or the like. In such a case, it has been the usual practice to trim the object image into a square or rectangular shape conforming with the shape of the mounting space. This job is very troublesome and time-taking and requires meticulous skill. Therefore, there have been demands for development of a drafting or drawing implement which can facilitate the trimming jobs.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a trimming square set which can form a desired rectangular shape in a simple and quick manner by the use of a couple of square members.
It is another object of the invention to provide a trimming square set which permits trimming of rectangular shapes of arbitrary length-to-width ratios quickly in a facilitated manner.
It is a further object of the invention to provide a trimming square set which permits trimming of rectangular shapes of arbitrary areal ratios quickly in a facilitated manner.
The trimming square set according to the invention basically comprises: a base plate having a circular opening therein; a first square member having inner edges set at right angles to each other and pivotally supported on the base plate by a pin member located at a position proximate to the peripheral edge of the circular opening, at a point proximate to an intersecting point of the inner edges; a slide plate being slidingly movable on said base plate in a direction parallel with an imaginary line passing through the center of the pin member and the circular opening and provided with a semi-circular notch on the inner side thereof congruently with the shape of the peripheral edge of the circular opening of said base plate; and a second square member having inner edges set at right angles to each other and pivotally supported on the slide plate on said base plate by a second pin member located on the imaginary line and in a position proximate to the peripheral edge of the semi-circular notch, at a point proximate to the intersecting point of the inner edges thereof.
With the above-described arrangement, utilizing the rule that the four apeces of a rectangle are located on one and same circumference, a rectangle is formed in an extremely simple manner by setting the semi-circular notch of the slide plate congruently on the circular opening of the base plate and positioning the inner edges of one square member on a point of intersection of the inner edges of the other square member with the marginal edge of the circular opening of the base plate. In addition, after forming a rectangle in this manner, similar rectangular shapes of arbitrary sizes can be formed simply by sliding the slide plate.
Further, the trimming square set according to the invention is provided with a scale of length-to-width ratio along the peripheral edge of the circular opening of the base plate or of the semi-circular notch of the slide plate which is shaped congruently with the circular opening, so that a rectangle of a desired length-to-width ratio can be obtained simply by aligning the semicircular notch of the slide plate with the circular opening in the base plate and positioning the inner edges of one square member on the graduations of the desired length-to-width ratio. This is especially convenient when trimming a photograph or drawing into a rectangular shape of a given length-to-width ratio.
Moreover, the trimming square set according to the invention is provided with a scale of areal reduction ratio on part of frames provided around the outer periphery of the base plate, indicating the areal reduction ratios of the rectangular shape which is formed by the inner edge
REFERENCES:
patent: 2342525 (1944-02-01), Berry
patent: 2494077 (1950-01-01), Wilkinson
patent: 2646626 (1953-07-01), Palin
patent: 2972811 (1961-02-01), Swayze
patent: 4417399 (1983-11-01), Baliozian
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