Patent GB-1311532-A (GB)
Title: Electronic device for plane graphical representation with perspect ive effect
IPC: G06F3/13
Filed: 1970-03-24
Abstract: 1311532 Perspective representation M N COLLET 24 March 1970 [24 March 1969] 14272/70 Heading G4G [Also in Division H4] A. curve-tracing arrangement for providing a plane graphical representation, with perspective, of the variation of three electrical signals x, y and z supplied over channels X, Y and Z, includes an electronic device having a signal distributer for receiving the signals x, y, z and for amplifying and combining them to provide output signals a and b such that and where the amplification coefficients k, l, m, and n, are independent of each other, and may be either positive or negative. As shown, the signals x, y and z are amplified or attenuated by desired amounts by components F, the resultant signal r from channel Z being applied to network RE to provide two signals p and q which are proportional to r and are respectively added to the amplified or attenuated x and y signals in the differential amplifiers AD and BD to provide the output signals a and b, which may be employed to control the display on a curve tracer T, which may be either an oscilloscope or a tracing table, to produce a representation of the three signals consistent with isometric projection. Alternatively, if the gain of the amplifiers F in channels A and B is arranged to be a function of the amplitude of signal r, a representation in artistic perspective is produced. The network RE may be either a simple junction, or an arrangement of two potentiometers connected in parallel and having ganged sliders (Fig. 3, not shown), on a transformer (Fig. 4, not shown)-preferably a two phase selsyn (Fig. 5, not shown), or a three-phase selsyn (Fig. 6, not shown). The X, Y and Z co-ordinate axes may be traced by the application of a corresponding x, y or a z signal-e.g. of sinusoidal form, and the co-ordinate planes by applying successively the appropriate pairs of x, y and z signals, the two members of a pair in a combination which forms a Lissajou figure (Fig. 7, not shown); by applying three such signals simultaneously a right prism seen in isometric perspective is produced (Fig. 8, not shown). The trajectory of a point-e.g. the co-ordinate of the centre of gravity of an object-may be represented, relative to a reference figure seen in isometric perspective, by use of an oscilloscope or tracing table having an after-glow screen. A trajectory varying in time may be studied by producing successive displacements of the origin of coordinates along the X-axis by adding a progressively stepped signal to the x input signal, so that representations of successive forms of the trajectory are displaced and appear side-by-side (Fig. 10, not shown). The signals for investigation may alternatively be employed to modulate constant high frequency signals, whereby the absence of the signals of interest corresponds to the display of a rectangular parallelopiped seen in perspective, and the presence of these signals produces distortion of the faces and edges of the parallelpiped, to which the eye is very sensitive. In such an arrangement, by appropriate choice of amplification factors, the distortion of the displayed figure may directly represent the distortion of a corresponding solid body, in a stress-strain investigation.