Geometrical instruments – Scriber
Patent
1981-11-20
1984-06-05
Stearns, Richard R.
Geometrical instruments
Scriber
33DIG1, 434 85, 434409, B43L 1300
Patent
active
044519850
DESCRIPTION:
BRIEF SUMMARY
This invention relates to drawing apparatus. It concerns the type of apparatus in which a line is drawn on the coated, inaccessible side of a screen by a remote controlled stylus which etches away part of the coating. The figure shows through the screen as it is created, and the coating can subsequently be restored to entirety, ready for a fresh drawing. Such a coating is generally a powder of such fineness that it will adhere to a glass or plastics screen by surface tension. The screen forms the top of a closed box containing the powder, and by inverting the box the screen is completely covered. On re-inversion, sufficient powder particles remain adhering to form a completely opaque screen. Such apparatus is primarily a toy or for playing graphic games, although it could have more serious uses, for example in teaching.
In one known form the stylus is controlled by two independently operable knobs which move the stylus in mutually perpendicular directions. Straight lines in those directions are then simple, but curves, circles and straight lines in other directions extremely difficult. There also tend to be problems with the complex mechanics of the two traverse mechanisms. It is the aim of this invention to make such apparatus simpler and yet more versatile.
According to the present invention there is provided drawing apparatus comprising a closed chamber one wall of which is a translucent screen and which contains liquid or powder of non-magnetic material that will adhere as a coating to said screen even when the interior surface thereof is downwardly facing, a scriber within the chamber for co-operating with said screen, and a movable guide member external to the chamber, the scriber and guide member having a mutual magnetic attraction so that movement of the guide member adjacent the chamber causes the scriber to trace a corresponding line in said coating, visible externally.
The screen does not have to be flat and rectangular, and generally there are few restrictions on its shape.
The re-coating will be achieved by temporarily inverting the chamber, as described previously. Powder will be preferred, but some viscous liquids may be suitable.
It is highly desirable that only the stylus should touch the interior surface of the screen. Therefore, arrangements will be made to ensure that the scriber will not impinge at any other point. Also, it is very important that the scriber should not build up a lump of powder or blob of liquid that would smear or produce an ill-defined line. Therefore arrangments will also be made to ensure that there is immediate clearance for the material etched away by the stylus.
The magnetic attraction may be generated in several ways, preferably by means of a rare earth magnet. There may be two permanent magnets, one in the scriber, the other in the guide member, or one could include material of high magnetic permeability, and the other a permanent magnet, or (if on the guide member) an electromagnet.
In one preferred form, means may be provided for generating electrical signals in response to the drawing of a picture, and for generating a sound related to the picture if it is drawn in a predetermined manner.
For a better understanding of the invention some embodiments will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a diagrammatic cross-section of a drawing apparatus, showing a scriber and a guide member,
FIG. 2 is a plan view to a larger scale of the scriber of FIG. 1,
FIG. 3 is a vertical section through another scriber and associated guide member,
FIG. 4 is a plan view of the scriber of FIG. 3,
FIG. 5 is a plan view of a practical embodiment of drawing apparatus, also incorporating a sound system,
FIG. 6 is a section on the line VI--VI of FIG. 5,
FIG. 7 is a section on the line VII--VII of FIG. 5, and
FIG. 8 is a circuit diagram of a sound producing system.
The drawing apparatus of FIG. 1 comprises a shallow box 1 inside which is a scriber 2 and outside which is a guide member 3, henceforth simply referred to as a pen
REFERENCES:
patent: 3055113 (1962-09-01), Grandjean
patent: 3103751 (1963-09-01), McDonald
patent: 3416231 (1968-12-01), Mercorelli
patent: 3585735 (1971-06-01), Miller
patent: 3760505 (1973-09-01), Clark
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