Claims
- 1. A drawing device for producing line drawings or sketches, said device comprising:
- (a) a box-like case provided at its top with a transparent screen, said case being partly filled with a slightly adhesive powder that adheres to the undersurface of the screen to render it opaque;
- (b) transverse and longitudinal rods disposed within the case, whereby the rods intersect at a point depending on the relative positions of the rods in the case;
- (c) control means including first and second knobs operatively coupled to said rods whereby when the first knob is turned, the transverse rod is shifted toward either end of the case, and when the second knob is turned the longitudinal rod is shifted toward either side of the case;
- (d) an indexable stylus turret and carrier assembly supported at the intersection of the rods, said turret which is received within the carrier being slidably supported on one rod and the carrier being slidably supported on the other rod whereby said assembly is caused to assume a position that depends on the point of intersection, said turret having a plurality of styluses at spaced positions on its rim, each stylus having a distinctive line drawing characteristic; and
- (e) indexing means including an actuator bar operatively coupled through said rods to said assembly to index said turret to present to the undersurface of said screen a selected one of said styluses.
- 2. A device as set forth in claim 1, wherein said plurality of styluses includes a stylus producing a thin line, a stylus producing a medium width line and a stylus producing a broad line.
- 3. A device as set forth in claim 1, wherein said plurality of styluses includes a stylus formed by four tips at the corners of a diamond to produce three parallel lines.
- 4. A device as set forth in claim 1, wherein said turret includes a blank stylus which when presented to said screen results in an interruption in the line then being drawn.
- 5. A device as set forth in claim 1, wherein the end portions of each rod are supported on respective slides ridable on parallel rails.
- 6. A device as set forth in claim 5, wherein the slides supporting each rod are fastened to a continuous string which is looped over pulleys, one of which is a drive pulley coupled to the related knob.
- 7. A device as set forth in claim 6, wherein each slide is provided with a guide stylus that engages the undersurface of the screen.
- 8. A device as set forth in claim 1, wherein said turret is received in a cavity of said carrier and said indexing means, when actuated, causes said turret to drop in said cavity to engage an abutment therein causing it to index.
- 9. A device as set forth in claim 8, wherein said turret is provided with lateral pins, each of which engages said abutment to cause indexing of the turret.
Related Application
This application is a continuation-in-part of our copending patent application Ser. No. 193,879, filed May 13, 1988, entitled "Drawing Device Having Retractable Stylus," the entire disclosure of which is incorporated herein by reference now U.S. Pat. No. 4,856,197.
1. Field of Invention
This invention relates generally to a drawing device having a shiftable stylus adapted to draw on the undersurface of a screen rendered opaque by powders, various line drawings or sketches whose contours depend on the operator-controlled path taken by the stylus as it scrapes powder from the screen, and more particularly to a drawing device of this type which includes a stylus turret which is indexable to present to the underside of the screen any one of a plurality of styluses to draw a line or group thereof whose character depends on the operative stylus or to present a blank stylus to interrupt the weak line being drawn.
2. Status of Prior Art
The Grandjean patent No. 3,305,113, and the Clark patent No. 3,760,505, disclose a tracing device having educational as well as play value. The tracing device includes a box-like case having a transparent glass plate or screen below which are left and right control knobs. By turning these knobs, one can delineate on the screen various letters, charts, designs and other line drawings and sketches.
In a tracing device of this type, one well known version which is commercially available under the trademark Etch-A-Sketch, in order to form a horizontal line in the X-direction on the screen, the operator has only to turn the left knob, while to form a vertical line in the Y direction, he turns the right knob. And to create curves and angles on the screen, these knobs are concurrently turned, thereby causing the stylus to shift in a path which is the vector resultant of the X and Y movements. The terms "drawing" and "tracing" as used herein are interchangeable, as are the terms "shiftable" and "movable."
The case is partly filled with a slightly adhesive powder which sticks onto the undersurface of the screen to render it opaque but is easily dislodged therefrom. The undersurface of the screen is engaged by the movable stylus which under knob control scrapes powder from the screen to define a line whose contour depends on the operator-controlled path taken by the stylus.
To erase the line drawing or sketch defined by the scraped-off powder on the screen, the case is turned upside down and is shaken to cause the powder to cascade over the undersurface of the screen, to again form an opaque coating.
The later-issued Clark patent differs from the earlier Grandjean patent mainly in the means incorporated therein to prevent leakage of powder from the tracing device. Both patents make use of transverse and longitudinal rods at whose intersection the stylus is mounted for sliding movement. The transverse rod is fastened at its extremities to parallel sections of a first string loop operatively coupled to the left control knob so that as this knob is turned, the transverse rod and the stylus borne thereby are caused to move toward either end of the box, depending on the direction of knob rotation, thereby drawing a horizontal line on the screen. The longitudinal rod is fastened at its extremities to parallel sections of a second string loop operatively coupled to the second knob so that as this knob is turned, this rod and the stylus borne thereby are caused to move toward either side of the box, thereby drawing a vertical line on the screen.
Thus, operation of one knob produces a line in the X-direction on the screen, operation of the other knob produces a line in the Y-direction, and concurrent turning of the knobs produces a line in a Z-direction which is the vector resultant of the X and Y movements of the stylus. The drawing device is therefore capable of creating line drawings or sketches having a desired configuration.
The most serious practical limitation of the tracing device of the type disclosed in the Clark and Grandjean patents as well as in commercially-available devices based on these patents is the inability of these devices selectively to interrupt the line drawn by the stylus. The stylus is urged against the undersurface of the screen under the tension of the string loops supporting the intersecting rods on which the stylus is mounted, and the stylus is never retracted therefrom. Because of this limitation, whatever drawing or sketch is traced on the screen by the operator must be formed by unbroken or continuous lines.
To explain why this limitation is troublesome, let us assume that a child wishes to draw with a pencil a simple picture composed of a house at ground level above which is the sun, a cloud and an airplane. These elements of the picture are all discrete and separated from each other in space. If, now, the child wishes to draw the same picture on a standard drawing device in which the stylus effectively performs the function of a pencil, he cannot on the screen of the drawing device create the elements thereof in discrete form, for the stylus never leaves the screen.
Hence, after completing, say, the house, in order now to draw the sun the child must trace a line from the house to a point thereabove before outlining the sun, and do likewise when going from the sun to a cloud, and from the cloud to an air plane. As a consequence, the picture is impaired by connecting lines which serve no artistic purpose but are dictated by the limitations of the tracing device. And when the child wishes with the tracing device to print on the screen an expression such as HAPPY BIRTHDAY, the letters cannot be separately traced but must be joined together as in cursive writing. Thus, however the knobs are manipulated, the operator can never lift the stylus from the screen as one can lift a pencil from paper.
Our above-identified patent Ser. No. 4,856,197 discloses a drawing device whose stylus is capable of being moved under the control of X-direction and Y-direction knobs to create on a screen various line drawings and sketches having any desired contour, the device further including a manually-operated interrupter mechanism which when actuated acts to retract the stylus from the screen without inhibiting movement of the stylus under knob control. This arrangement makes possible the formation on the screen of a drawing or sketch composed of discrete, multiple elements without the need to interconnect these elements with lines as in prior tracing or drawing devices.
In the drawing device disclosed in patent No. 4,856,197, disposed within the case is a stylus supported for sliding movement at the intersection of shiftable transverse and longitudinal rods. The moving stylus normally engages the undersurface of the screen and acts to scrape powder therefrom to create a line whose contour depends on the path taken by the stylus under the control of one or both knobs. In order to produce sketches and drawings having discrete elements, a manually-operated interrupter mechanism is provided which when actuated depresses one of the rods to retract the stylus from the screen without, however, inhibiting shifting thereof, whereby it then becomes possible selectively to interrupt the line drawn thereby.
Of prior art interest with respect to retractable styluses are the patents to Gresset Nos. 4,135,303, and Klawitter, 4,550,503.
The limitations of prior drawing devices of the above-described type is that they are capable only of producing sketches or drawings in which the lines all have exactly the same thickness. From the artistic standpoint, this restricts the expressive range of the drawing device, and it is as if an artist were required to work always with a pencil or crayon that has a fixed fine point, so that he could not produce lines of medium or gross thickness and thereby be able to highlight certain features and attenuate others.
In view of the foregoing, the main object of this invention is to provide a drawing device capable of drawing lines of different thickness or character by scraping powder from the undersurface of a screen rendered opaque by powder.
More particularly, an object of this invention is to provide a drawing device having a shiftable stylus for drawing on the undersurface of a screen rendered opaque by powder, the stylus scraping powder from the screen to produce line drawings whose contours depend on the operator-controlled path taken by the stylus, the device including an indexable stylus turret to present to the underside of the screen any one of a plurality of styluses or to present a blank stylus to interrupt the drawn line.
A significant advantage of the invention is that the operator of the drawing device has selectively available several styluses, each producing a distinctive line of predetermined thickness or a group of lines, so that in making a drawing, the operator can vary the character of the drawn line and thereby enhance the expressive nature of the drawing.
Also an object of this invention is to provide a drawing device of the above type which includes a pair of control knobs by which the operator can shift an indexable stylus turret in the X and Y directions or in a direction which is the vector resultant of X and Y movement, the turret being indexed by an actuator accessible to the operator to present to the screen a stylus of the desired character.
Still another object of the invention is to provide a drawing device whose screen is protectively covered by a transparent plastic sheet, whereby should the screen shatter as a result of an accident, the particles thereof will remain within the device.
Briefly stated, these objects are attained in a drawing device adapted to produce line drawings or sketches on a transparent screen on top of a case partly filled with a powder that adheres slightly to the undersurface of the screen to render it opaque. Disposed within the case are transverse and longitudinal rods operatively coupled to respective control knobs, one of which, when turned, causes the longitudinal rod to shift toward either side of the case, the other of which, when turned, causes the transverse rod to shift to either end of the case.
Supported at the intersection of the rods is an indexable stylus turret and carrier assembly whose carrier is slidably supported on the transverse rod and whose stylus turret which is received within the carrier is slidably supported on the longitudinal rod whereby the position occupied by the assembly is determined by the position of the intersection. The turret is indexable to present to the underside of the screen, for scraping powder therefrom to draw a line, any one of several styluses each producing a line of different width or character or to present a blank stylus which interrupts the drawn line. Indexing is effected by pressing an actuator bar operatively coupled to the longitudinal rod carrying the turret to depress this rod and to cause a turret pin to engage an abutment in the carrier, this action turning the turret to its next operative position.
US Referenced Citations (10)
Non-Patent Literature Citations (1)
| Entry |
| Streifler, J. J., "Plastic Scribing" Photogrammetric Engineering, Apr. 1957, vol. 23, no. 2, pp. 330-335. |
Continuation in Parts (1)
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Number |
Date |
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193879 |
May 1988 |
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Patent Grant
4949466
