GB2054175A

GB2054175A - Method of and Apparatus for Producing Raster Drawings using a Computer-controlled Drawing Machine

Info

Publication number: GB2054175A
Application number: GB8020524A
Authority: GB
Original assignee: Aristo Graphic Systeme GmbH and Co KG
Current assignee: Aristo Graphic Systeme GmbH and Co KG
Priority date: 1979-06-25
Filing date: 1980-06-23
Publication date: 1981-02-11
Also published as: JPS588998B2; FR2460025A1; SE8004631L; DE2925612A1; JPS568298A; GB2054175B

Abstract

Raster drawings are produced using a computer-controlled drawing machine which has a drawing table 2 in the form of a disc rotatably mounted about its central axis and carries a drawing support. A guide 3 holds a drawing head 7 above the table and extends, in an operative position, diametrically relative to the axis of rotation of the table. Means are provided for moving the drawing head continuously along the guide at least between the centre and the edge of the drawing table while the drawing head intermittently strikes the drawing support with a drawing medium 9 which applies raster dots in spiral paths to the drawing support. Either the drawing head or the drawing table may be driven at constant speed while the other may be driven at a variable speed depending upon the operative radius. The drawing medium may be ink or, if the drawing support is light-sensitive, light. <IMAGE>

Description

SPECIFICATION Method of and Apparatus for Producing Raster Drawings Using a Computer-controlled Drawing Machine The invention relates to a method of and an apparatus for producing raster drawings using a computer-controlled drawing machine.

Conventional drawing machines produce only line drawings and lettering, but are not capable of drawing solid areas. If there is a need to draw solid areas, those parts of the drawings which are to be drawn as solid areas have to be provided with a plurality of dots located close together and possibly overlapping. Drawing heads for drawing machines which apply raster dots of this kind are already in existence. Up till now, the operating speed of drawing machines of this kind when producing raster drawings has been relatively slow and has been limited primarily by the fact that the mass of the moving drawing head has to be accelerated in varying directions.

Corresponding inertia phenomena also result if there is no relative movement of the drawing head but the drawing support itself has to be moved and accelerated in the longitudinal and transverse directions. Furthermore, distortion and deformation of the drawing support must be expected when it moves at fairly high speeds.

It is an object of the invention to provide an inexpensive method and apparatus with which raster drawings can be produced at substantially higher speeds.

According to one aspect of the present invention there is provided a method of producing raster drawings by means of a computercontrolled drawing machine, wherein a drawing support is set in rotation on a rotating drawing table below a drawing head moving radially relative to the axis of rotation of the drawing table, and wherein the drawing head intermittently strikes the drawing support with the drawing medium which applies raster dots in spiral paths to the drawing support.

According to another aspect of the present invention there is provided apparatus for producing raster drawings, wherein a drawing machine adapted to be controlled by a computer has a drawing table in the form of a rotatably mounted circular disc, there being means for rotating said disc about its central axis and wherein a guide for holding a drawing head above said table extends in an operative position diametrically relative to the axis of rotation of the drawing table, there being means for continuosly moving the drawing head along the guide, at least between the centre and the edge of the drawing table.

When the present method is performed, control signals which are normally present in polar coordinates are converted into comprehensive form.

The drawing head and drawing table may be driven at constant speed. However, in order to obtain a constant travel speed for the drawing head, it is also posible to drive the drawing head at constant speed and to drive the drawing table at a variable speed which depends upon the operating radius. Conversely, it is also possible to drive the drawing table constant speed and to drive the drawing head at a variable speed depending upon the operating radius.

Preferably the guide for the drawing head is a carriage spanning the drawing table like a bridge and movable from a lockable operation position into a resting position located beside the edge of the drawing table. In one embodiment, a spindle nut is mounted in the drawing head and engages a spindle which is provided in the guide and extends longitudinally thereof, there being means for rotating the spindle thereby to move the drawing head. Alternatively, a toothed rack may be provided in the guide and extend longitudinally thereof, while a pinion mounted on the drawing head engages in the toothed rack. Means are provided for driving said pinion thereby to move the drawing head. In a further alternative, a motor-drivable belt may be mounted between the drawing head and the guide.

If the drawing support is light-sensitive, the raster dots may be produced using light as the drawing medium. Preferably, however, the drawing head is provided with intermittently operable ink ejector means and may be provided with a plurality of alternately usable drawing pens and/or ink ejector means.

In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawing, which illustrates diagrammatically and by way of Example an embodiment thereof, and which is a perspective view of a rotatable drawing table with a radially movable drawing head.

Referring now to the drawing, there is shown a drawing machine of which the externai structure is similar to that of known polar coordinator graphs. The drawing machine 1 consists of a table-shaped frame with a table top 11 and four table legs 12 having feet 13 which are adjustable in height. In the table top 11 there is a circular recess 14 for the drawing table 2 itself which is in the form of a rotatably mounted circular disc.

Drawing supports 10 of any desired form may be placed on the drawing table and be held in place by suction or adhesion. The drawing table 2 has a vertically extending axis of rotation (not shown) and can be set in rotation by means of a motor 17 mounted underneath the table. The mounting of the drawing table and the location of the axis of rotation thereof enable the drawing table 2 to rotate accurately and without friction inside the table recess 14.

Above the drawing table 2 there is a guide 3 for a drawing head 7, the guide 3 extending precisely diametrically relative to the axis of rotation of the drawing table in the working position.

Although the guide 3 may be fixedly connected to the frame of the drawing machine, it is advantageous to construct the guide 3 in the form of a carriage which is movable on laterally mounted rails 4 and 5 extending parallel to each other. For this purpose, feet comprising rollers 6 or slide members which engage the rails 4 and 5 are provided at the ends of the guide 3. The reason for the mobility of the guide 3 is that, in order to study the drawing support or put it in place or remove it, the guide can be moved into a marginal position in which the entire drawing table 2 is free. Preferably, a locking device with which the exact diametric position of use can be fixed is provided on the rails 4 and 5 and on the feet of the guide 3 which is constructed as a carriage.This fixing can be effected using means known per se, by actuating a locking lever 1 5 mounted on the side wall of the table.

Inside the guide 3 there is a screw spindle, not shown in detail, which can be driven by a motor 16 mounted at the end of the guide 3. The drawing head 7 contains a spindle nut for engaging in the screw spindle. The screw spindle and spindle nut are arranged so that the drawing head 7 is movable at least between the centre of the drawing table 2 and the edge thereof. By means of an actuating mechanism 8 provided on the drawing head, ink ejector means 9 of the drawing head can be actuated intermittently in accordance with the signals fed in by the computer. If a plurality of ink ejector means for different colours or different drawing pens are provided, the corresponding pieces of equipment may also be brought into use alternatately using the actuating mechanism 8.

When the drawing machine shown in the drawing is used, the guide 3 is moved into a marginal position and drawing support 10 is fixed to the drawing table; if drawing heads using light are used, the drawing support may be a lightsensitive drawing support. The guide 3 is then brought into the diametric central position and the drawing table 2 is set in rotation by the motor 1 7. During the drawing operation, the drawing head 7 with the ink ejector means 9 moves constantly outwards from the central position to the edge of the drawing table. In this way, the raster dots to be applied are provided on the drawing support in the spiral paths, thus giving an areal representation when the drawing is finished.

The table motor 1 7, the spindle motor 16 of the guide 3 and the actuating mechanism 8 are controlled by means of a computer in the usual way.

If the computer can only make use of stored Cartesian coordinates, these have to be converted into polar coordinates before the drawing machine is controlled.

The motors 1 7 and 16 may run at constant speed so that the speed of drawing becomes constantly greater as the operating radius increases. When the raster dots are at a prescribed spacing, the actuating mechanism, which is also controlled by the computer, then has to work faster as the operating radius increases.

If it is desired to move the drawing head at a substantially constant travel speed relative to the drawing support 10, one of the motors 17 or 16 can be driven at constant speed and one of the motors 1 7 and 1 6 can be driven at variable speed, whilst the variable speed should be selected so as to increase in proportion to the operating radius which is becoming larger.

Claims

1. A method of producing raster drawings by means of a computer-controlled drawing machine, wherein a drawing support is set in rotation on a rotating drawing table below a drawing head moving radially relative to the axis of rotation of the drawing table, and wherein the drawing head intermittently strikes the drawing support with the drawing medium which applies raster dots in spiral paths to the drawing support.

2. A method as claimed in claim 1, wherein the drawing medium is ink.

3. A method as claimed in claim 1, wherein the drawing medium is light and the drawing support is light-sensitive.

4. A method as claimed in any one of claims 1 to 3, wherein the drawing table is driven at constant speed.

5. A method as claimed in any one of claims 1 to 3, wherein the drawing head is driven at constant speed.

6. A method as claimed in any one of claims 1 to 3 and 5, wherein the drawing head is driven at constant speed and the drawing table is driven at variable speed which is dependent upon the operating radius and corresponds to a constant travel speed of the drawing head relative to the drawing support.

7. A method as claimed in any one of claims 1 to 4, wherein the drawing table is driven at constant speed and the drawing head is driven at variable speed which is dependent upon the operating radius and corresponds to a constant travel speed of the drawing head relative to the drawing support.

8. A method of producing raster drawings by means of a computer-controlled drawing machine substantially as hereinbefore described with reference to the accompanying drawing.

9. Apparatus for producing raster drawings, wherein a drawing machine adapted to be controlled by a computer has a drawing table in the form of a rotatably mounted circular disc, there being means for rotating said disc about its central axis and wherein a guide for holding a drawing head above said table extends in an operative position diametrically relative to the axis of rotation of the drawing table, there being means for continuously moving the drawing head along the guide, at least between the centre and the edge of the drawing table.

10. Apparatus as claimed in claim 9, wherein the guide for the drawing head is a carriage spanning the drawing table like a bridge and movable from a lockable operative position into a resting position located beside the edge of the drawing table.

1 Apparatus as claimed in claims 9 or 10, wherein a spindle nut is mounted in the drawing head and engages a spindle which is provided in the guide and extends longitudinally thereof, there being means for rotating the spindle thereby to move the drawing head.

12. Apparatus as claimed in claim 9 or 10, wherein a toothed rack is provided in the guide and extends longitudinally thereof, while a pinion mounted on the drawing head engages in said toothed rack, there being means for driving said pinion thereby to move the drawing head.

13. Apparatus as claimed in claim 9 or 10, wherein a motor-drivable belt drive is mounted between the drawing head and the guide.

14. Apparatus as claimed in any one of claims 9 to 13, wherein the drawing head carries intermittently operable ink ejector means.

1 5. Apparatus as claimed in any one of claims 9 to 13, wherein the drawing head is provided with a plurality of alternately useable drawing pens and/or ink ejector means.

1 6. Apparatus as claimed in any one of claims 9 to 13, wherein the drawing head is a lightoperable drawing head and the drawing table is constructed for use with iight-sensitive drawing supports.

1 7. A modification of the apparatus claimed in any one of claims 9 to 16 for vectorial computercontrolled drawing, wherein a drive motor of a drawing table mounted so as to have a low friction and inertia and a radially operating drive motor for the drawing head are arranged to be moved along predetermined paths in accordance with a polar coordinate movement of the drawing head.

18. Apparatus for producing raster drawings substantially as hereinbefore described with reference to the accompanying drawing.