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Plotting and Recording Curves using a Printer

IP.com Disclosure Number: IPCOM000088060D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 4 page(s) / 54K

Publishing Venue

IBM

Related People

Huet, H: AUTHOR [+2]

Abstract

This method enables drawings, graphs, mathematical curves or curves representative of data processing operations to be very quickly printed on a paper medium, using a printer adapted to form digits and/or characters by means of so-called elementary graphic signs.

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Plotting and Recording Curves using a Printer

This method enables drawings, graphs, mathematical curves or curves representative of data processing operations to be very quickly printed on a paper medium, using a printer adapted to form digits and/or characters by means of so-called elementary graphic signs.

Each character or digit position on the medium takes the form of a rectangle (such as rectangle pqrs defining position Pk1 in Fig. 3) approximately 3.17 mm long and 1.69 mm wide for a printer printing 8 lines per inch and 15 characters per inch.

As shown in Figs. 1 and 2, six reference points are defined along each vertical side and three reference points are defined along each horizontal side of each rectangle pqrs. These reference points serve to identify the segments of straight or curved lines that join any two of the 18 reference points on the periphery of each character or digit position, the segments being referred to herein as elementary graphic signs.

The two reference points may be located on adjacent (Fig. 1B) or nonadjacent (Fig. 1C) sides of a rectangle pqrs. They may also be located on the same side, in which case the graphic sign is comprised of a segment of a curve consisting, for example, of a half-circle (Fig. 1D).

A common characteristic of the elementary graphic signs shown in Fig. 1A- 1D is that they consist of segments of straight lines and segments of curves connecting any two reference points selected from the 18 reference points on the periphery of a rectangular character position. Accordingly, up to 153 graphic signs of this type may be defined.

Other graphic signs may be defined according to the nature or the characteristics of the desired curves or drawings. Some graphic signs of another set of elementary graphic signs are represented in Figs. 2A-2D.

Segments of curves of the type shown in Fig. 2A make it possible to obtain a more accurate representation of the peaks of a curve y = f(x). The graphic signs in Figs. 2B and 2C combine vertical or slanted lines to represent either curves with closely spaced peaks or two closely-spaced, but separate, curves. The graphic sign in Fig. 2D serves to provide a more accurate representation of the angles of a curve or a drawing.

Assuming that a curve such as curve (C) in Fig. 3 is to be plotted, the points where the curve intersects the various horizontal lines H and vertical lines V, which delimit the various character positions P, are first determined. This calculation can be performed either by the user, i.e., the person who desires to reproduce curve (C), assuming he knows its equation or some of its coordinates, or by a computer storing the coordinates of the curve, as defined by a program.

In each of the character positions P, the elementary graphic sign that most closely resembles the curve portion to be reproduced is selected from the set of graphic signs available to the printer. Using the graphic signs of Fig. 1, portions

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